TW202323487A - Adhesive composition, adhesive, adhesive sheet, adhesive sheet with release film, laminate for image display device, curved image display device, adhesive composition for curved optical member - Google Patents

Abstract

The present invention relates to the useful improvement of an adhesive composition that can be used for multistage curing and to the use thereof. The adhesive composition contains an acrylic resin (A) and a photoinitiator (B). The acrylic resin (A) is a polymerization product of a copolymer component (a). The copolymer component (a) contains an alkyl acrylate (a1) that has a glass transition temperature of -30 to 50 DEG C when a homopolymer is formed and an alkyl methacrylate (a2) that has a glass transition temperature of -10 to 120 DEG C when a homopolymer is formed. The total content of alkyl acrylate (a1) and alkyl methacrylate (a2) is 5 wt% or more relative to 100 wt% of copolymer component (a). Application examples of the adhesive composition relate to an adhesive, an adhesive sheet, an adhesive sheet with a release film, a laminate for an image display device, a curved image display device, and an adhesive composition for a curved optical member.

Description

Adhesive composition, adhesive, adhesive sheet, adhesive sheet with release film, laminate for image display device, curved image display device, adhesive composition for curved optical member

The present invention mainly relates to an adhesive composition, an adhesive, an adhesive sheet, an adhesive sheet with a release film, a laminate for an image display device, a curved image display device, and an adhesive composition for a curved optical member. This case is based on Japanese Patent Application No. 2021-160337 filed at the Japan Patent Office on September 30, 2021, Japanese Patent Application No. 2021-160485 filed at the Japan Patent Office on September 30, 2021, and Japanese Patent Application No. 2021-160485 filed at the Japan Patent Office on September 30, 2021 Priority is claimed in Japanese Patent Application No. 2021-160488 filed by the JPO, and the contents thereof are incorporated herein.

In recent years, touch panels combining displays and position input devices have been widely used in mobile devices such as TVs or personal computer monitors, notebook computers, mobile phones, smart phones, and tablet terminals. Among them, the electrostatic capacitive touch panel is widely popularized. A touch panel usually includes: a display containing organic EL (Electroluminescence, electroluminescence) or liquid crystal, a transparent conductive film substrate (ITO substrate), and a protective film (protective glass). The components of these touch panels are attached using transparent adhesive sheets.

Since the transparent adhesive sheet needs to bond components of various shapes, the adhesive used for the transparent adhesive sheet is bonded in a low cross-linked state before it is completely hardened. Therefore, sufficient adhesive properties are required in the step before the adhesive layer in the low cross-linked state is completely cured. For example, in the case of attaching to components with complex shapes, it is easy to cause poor attachment due to the transparent adhesive sheet being attached outside the target position. Therefore, a transparent adhesive sheet with low tackiness is required. In addition, in order to fix members having complex shapes together, it is required to suppress peeling of the transparent adhesive sheet from the members in a state where stress is applied. Therefore, there is also a need for a transparent adhesive sheet with high constant load retention even in a low cross-linked state.

In addition, the fully hardened adhesive layer requires not only the usual adhesive properties such as adhesive force, but also performance that is excellent in reliability when it is bonded to various members such as polarizing plates and glass. For example, in order to obtain excellent durability after complete curing, it is required that the degree of crosslinking be as low as possible before bonding to an adherend. In addition, it is also required to efficiently increase the degree of crosslinking at the time of complete curing.

Therefore, it is expected that the adhesive layer can be fully adhered to the adherend by bonding the adhesive layer to the adherend in a low-crosslinked state. Furthermore, since the adhesive sheet is fully cured in a state of being bonded to an adherend in a low cross-linked state, the adhesive sheet has a high degree of cross-linking, and thus durability is expected to be improved. Usually, in primary curing, cross-linking and hardening are performed by thermal cross-linking or irradiation of active energy rays, and then cross-linking and hardening are performed by irradiation of active energy rays in complete curing. As an adhesive sheet using this multistage curable adhesive, the adhesive sheets described in patent documents 1-3 are mentioned, for example.

Patent Document 1 discloses that a solvent-based adhesive containing an acrylic resin further uses an organic solvent that is easily volatile under normal drying conditions, and that a non-volatile ethylenically unsaturated monomer is formulated at a specific ratio. In addition, Patent Document 2 discloses that in order to form a three-dimensional network structure of a solvent-based acrylic adhesive without using a crosslinking agent, a hydrogen abstraction-type photoinitiator is used, and photopolymerization is carried out after the coating and drying step. irradiation, thereby omitting the aging step. Furthermore, Patent Document 3 discloses that by using an acrylic resin with a high glass transition temperature, an adhesive with high step followability and foam resistance can be obtained. [Prior Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2012-111939 [Patent Document 2] Japanese Patent Laid-Open No. 2017-210542 [Patent Document 3] International Publication No. 2017/022770

[Problem to be solved by the invention]

However, none of Patent Documents 1 to 3 considered adhesive properties in a low-crosslinked state during primary curing. Therefore, since the adhesive properties in a low crosslinked state at the time of primary curing may become insufficient, there is room for improvement. In particular, in the application where the once-cured adhesive sheet is bonded to an adherend of a complex shape to which strong stress is applied, defects such as peeling of the adhesive sheet occur after bonding.

The purpose of the first aspect of the present invention is mainly to provide: an adhesive composition, which can be used for multi-stage curing, and can obtain excellent adhesive properties in a low cross-linked state after the first curing, and can also be used after complete curing. To obtain excellent adhesive properties and reliability; an adhesive obtained by crosslinking the above adhesive composition; and an adhesive sheet having an adhesive layer comprising the above adhesive.

The purpose of the second aspect of the present invention is mainly to provide: an adhesive composition, which can be used for multi-stage curing, and can obtain excellent adhesive properties in a low cross-linked state after the first curing, and can also be used after complete curing. To obtain excellent adhesive properties and reliability; an adhesive obtained by crosslinking the above adhesive composition; and an adhesive sheet having an adhesive layer comprising the above adhesive.

The purpose of the third aspect of the present invention is mainly to provide: an adhesive composition that can be used for multi-stage curing, and can also obtain excellent adhesion when it is attached to an adherend of a complex shape to which strong stress is applied. An adhesive sheet; an adhesive obtained by crosslinking the above adhesive composition; and an adhesive sheet having an adhesive layer containing the above adhesive. [Technical means to solve problems]

In order to solve the problem of the above-mentioned first aspect, the inventors of the present invention conducted intensive research and found that by using an adhesive composition containing an acrylic resin obtained by using a copolymerization component of a specific composition and a specific photoinitiator, In the low cross-linked state after primary hardening, excellent adhesive properties such as low tackiness and high constant load retention can also be achieved, and excellent adhesive properties and reliability can also be achieved after complete curing.

The first aspect of the present invention is an adhesive composition comprising an acrylic resin (A) and a photoinitiator (B); the acrylic resin (A) is a polymerization product of the following copolymerization component (a) ; The glass transition temperature of the acrylic resin (A) based on dynamic viscoelasticity is above -10°C; the photoinitiator (B) contains an intramolecular hydrogen abstraction type photoinitiator (b1) and an intermolecular hydrogen abstraction type photoinitiator (b1) Photoinitiator (b2).

The copolymerization component (a) of the first aspect contains at least an alkyl acrylate (a1) whose glass transition temperature when forming a homopolymer is -30 to 50°C, and whose glass transition temperature when forming a homopolymer is -10 to 120 Alkyl methacrylate (a2) and hydroxyl-containing monomer (a3) at ℃, the weight ratio of the above-mentioned alkyl acrylate (a1) to the above-mentioned alkyl methacrylate (a2) is 5/95～55/ 45. The total content of the above-mentioned alkyl acrylate (a1) and the above-mentioned alkyl methacrylate (a2) is 30 to 70% by weight based on the copolymerization component (a).

In order to solve the problem of the above-mentioned second aspect, the inventors of the present invention conducted intensive research and found that by using an adhesive composition containing an acrylic resin obtained by using a copolymerization component of a specific composition and a specific photoinitiator, In the low cross-linked state after primary hardening, excellent adhesive properties such as low tackiness and high constant load retention can also be achieved, and excellent adhesive properties and reliability can also be achieved after complete curing.

The second aspect of the present invention is an adhesive composition comprising an acrylic resin (A) and a photoinitiator (B); the acrylic resin (A) is a polymerization product of the following copolymerization component (a) ; The glass transition temperature of the acrylic resin (A) based on dynamic viscoelasticity is above -10°C; the photoinitiator (B) contains an intramolecular hydrogen abstraction type photoinitiator (b1).

The copolymerization component (a) of the second aspect contains at least: an alkyl (meth)acrylate (a1) having an alkyl group having 12 or less carbon atoms and having a homopolymer glass transition temperature of -20 to 120°C; and a hydroxyalkyl monomer (a2) containing an alkyl chain, a hydroxyl group, and an ethylenically unsaturated group, the content of the above-mentioned alkyl (meth)acrylate (a1) is 30% by weight relative to 100% by weight of the above-mentioned copolymerization component (a) % by weight or more; the content of the above-mentioned hydroxyalkyl monomer (a2) is 0.1% by weight or more relative to 100% by weight of the above-mentioned copolymerization component (a); the alkane of the above-mentioned hydroxyalkyl monomer (a2) in the copolymerization component (a) The average carbon number of the base chain is 2.1 or more.

In order to solve the problem of the above-mentioned third aspect, the inventors of the present invention conducted intensive research and found that by using an adhesive composition containing an acrylic resin obtained by using a copolymerization component of a specific composition and a specific photoinitiator, It is possible to obtain an adhesive sheet that can be adhered to a stress-applied complex-shaped adherend without peeling off even at the time of primary curing, and an adhesive sheet that exhibits excellent durability even after complete curing can be obtained.

The third aspect of the present invention is an adhesive composition, which contains an acrylic resin (A) and a photoinitiator (B); the acrylic resin (A) is a homopolymer with a glass transition temperature of -30 The polymerization product of the copolymerization component (a) containing branched alkyl (meth)acrylate (a1) above ℃; the glass transition temperature of the acrylic resin (A) based on dynamic viscoelasticity is above -10℃; The weight average molecular weight of the acrylic resin (A) is less than 400,000; the photoinitiator (B) contains intramolecular hydrogen abstraction photoinitiator (b1) and intermolecular hydrogen abstraction photoinitiator (b2). [Effect of Invention]

According to the first aspect of the present invention, it is possible to provide: an adhesive composition that can be used for multi-stage curing, and can obtain excellent adhesive properties in a low-crosslinked state after primary curing, and can also be obtained after complete curing Excellent adhesive properties and reliability; an adhesive obtained by crosslinking the above adhesive composition; and an adhesive sheet having an adhesive layer comprising the above adhesive.

According to the second aspect of the present invention, it is possible to provide: an adhesive composition that can be used for multi-stage curing, and can obtain excellent adhesive properties in a low cross-linked state after primary curing, and can also be obtained after complete curing Excellent adhesive properties and reliability; an adhesive obtained by crosslinking the above adhesive composition; and an adhesive sheet having an adhesive layer comprising the above adhesive.

According to the third aspect of the present invention, it is possible to provide an adhesive composition that can be used for multi-stage curing and can also obtain excellent adhesion when it is attached to an adherend of a complicated shape to which strong stress is applied. An adhesive sheet; an adhesive obtained by crosslinking the above adhesive composition; and an adhesive sheet having an adhesive layer containing the above adhesive.

The meanings of the following terms used in this specification are shown below. "(Meth)acrylic" means acrylic or methacrylic. "(Meth)acryl" means acryl or methacryl. "(meth)acrylate" means acrylate or methacrylate. "Acrylic resin" is a resin obtained by polymerizing a monomer component containing at least one (meth)acrylic monomer. "Sheet" is a term that conceptually includes sheet, film, and tape. "Homopolymer" means a homopolymer of a monomer. "～" indicating a numerical range means including the values recorded before and after it as the lower limit and upper limit.

[first form] Hereinafter, although the embodiment of the first aspect of the present invention will be described in detail, these are disclosed as representative examples of preferred implementation aspects.

<Adhesive composition> The adhesive composition of the first aspect contains an acrylic resin (A) and a photoinitiator (B). The adhesive composition of the first aspect may further contain a crosslinking agent (C), a silane coupling agent (D), and a carbodiimide in addition to the acrylic resin (A) and the photoinitiator (B). It is a compound (E) and other optional components. Hereinafter, each component is demonstrated sequentially.

(Acrylic resin (A)) The acrylic resin (A) of the first aspect is a polymerization product of the specific copolymerization component (a). The copolymerization component (a) is a general term for monomer components having a polymerizable double bond. The copolymerization component (a) does not contain a polymerization initiator or a polymerization solvent.

The specific copolymer component (a) of the first aspect contains at least an alkyl acrylate (a1) whose glass transition temperature when forming a homopolymer is -30 to 50°C, and whose glass transition temperature when forming a homopolymer is -10 Alkyl methacrylate (a2) and hydroxyl-containing monomer (a3) at ~120°C. The copolymerization component (a) of the first aspect may further contain alkyl acrylate (a1) having a glass transition temperature of -27 to 50°C and methacrylic acid having a glass transition temperature of 0 to 120°C when forming a homopolymer An ethylenically unsaturated monomer (a4) other than an alkyl ester (a2) and a hydroxyl group-containing monomer (a3).

[Alkyl Acrylate (a1)] The glass transition temperature (hereinafter referred to as "Tg") of the homopolymer of the alkyl acrylate (a1) of the first aspect is -30 to 50°C, preferably -27 to 45°C, more preferably -10 to 43°C, more preferably -5 to 10°C. If the Tg is within the range, the effect of the first aspect of the present invention can be obtained.

The homopolymer of alkyl acrylate (a1) is a homopolymer of alkyl acrylate (a1). As the Tg of the homopolymer of alkyl acrylate (a1), the analysis value of the standard described in "POLYMER HANDBOOK" published by Wiley etc. can be used.

As the alkyl acrylate (a1) of the first aspect, for example, methyl acrylate (Tg: 8°C), ethyl acrylate (Tg: -22°C), isobutyl acrylate (Tg: -26°C ), tert-butyl acrylate (Tg: 41°C), cyclohexyl acrylate (Tg: 15°C), etc. Among them, methyl acrylate is preferred in terms of adhesive properties. Alkyl acrylates (a1) may be used alone or in combination of two or more.

[Alkyl methacrylate (a2)] The Tg of the homopolymer of the alkyl methacrylate (a2) of the first aspect is -10 to 120°C, preferably 0 to 110°C, more preferably 20 ~105°C, more preferably 40-70°C. If the Tg is within the range, the effect of the first aspect of the present invention can be obtained. The homopolymer of alkyl methacrylate (a2) in the first aspect is a homopolymer of alkyl methacrylate (a2). As Tg of the homopolymer of the alkyl methacrylate (a2), the analysis value of the standard described in "POLYMER HANDBOOK" published by Wiley etc. can be used.

Examples of the alkyl methacrylate (a2) of the first aspect include: methyl methacrylate (Tg: 105°C), ethyl methacrylate (Tg: 65°C), n-butyl methacrylate ester (Tg: 20°C), isobutyl methacrylate (Tg: 48°C), cyclohexyl methacrylate (Tg: 66°C), tert-butyl methacrylate (Tg: 107°C), etc. Alkyl methacrylate (a2) may be used alone or in combination of two or more. Among them, methyl methacrylate, ethyl methacrylate, and isobutyl methacrylate are preferred.

[Hydroxyl-containing monomer (a3)] The first aspect of the hydroxyl-containing monomer (a3) contains one or more hydroxyl groups and ethylenically unsaturated groups. Examples of the hydroxyl group-containing monomer (a3) include: 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, (meth)acrylate ) 6-hydroxyhexyl acrylate, 8-hydroxyoctyl (meth)acrylate and other hydroxyl-containing alkyl (meth)acrylates; caprolactone-modified caprolactones such as 2-hydroxyethyl (meth)acrylate Modified monomers; polyethylene glycol mono(meth)acrylate, polybutylene glycol mono(meth)acrylate and other oxyalkylene modified monomers; 2-acryloxyethyl-2-hydroxy Primary hydroxyl-containing monomers such as ethyl phthalic acid, N-methylol (meth)acrylamide, hydroxyethyl acrylamide, etc.; 2-hydroxypropyl (meth)acrylate, (methyl) 2-hydroxybutyl acrylate, 3-chloro 2-hydroxypropyl (meth)acrylate and other monomers containing secondary hydroxyl groups; 2,2-dimethyl 2-hydroxyethyl (meth)acrylate containing tertiary hydroxyl groups Hydroxyl monomer.

Among them, the alkyl (meth)acrylate containing a primary hydroxyl group is preferable in terms of efficient curing at the time of complete curing, and the combination of 2-hydroxyethyl (meth)acrylate and (meth)acrylic acid is particularly preferable. base) 4-hydroxybutyl acrylate or 4-hydroxybutyl (meth)acrylate alone.

[Ethylenically unsaturated monomer (a4)] In the first aspect, the copolymerization component (a) may further contain other copolymerizable ethylenically unsaturated monomers (a4) other than monomers (a1) to (a3) ). Examples of other copolymerizable ethylenically unsaturated monomers (a4) include alkyl (meth)acrylates such as n-butyl acrylate and 2-ethylhexyl (meth)acrylate (among which, alkyl acrylate (except alkyl ester (a1) and alkyl methacrylate (a2)); phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenyldiethylenedi Alcohol (meth)acrylate, Phenoxypolyethylene glycol (meth)acrylate, Phenoxypolyethylene glycol-polypropylene glycol-(meth)acrylate, o-Phenylphenoxy (meth)acrylate Aromatic ring-containing monomers such as ethyl ethyl ester, nonylphenol ethylene oxide adduct (meth)acrylate; cyclohexyloxyalkyl (meth)acrylate, tertiary butyl ring (meth)acrylate Alicyclic monomers such as hexyloxyethyl ester, isomethacrylate, dicyclopentyl (meth)acrylate; 2-methoxyethyl (meth)acrylate, 2-(meth)acrylate Ethoxyethyl ester, 3-methoxybutyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-butoxydiethylene glycol (meth)acrylate, methoxy Diethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate Esters, Methoxypolyethylene glycol (meth)acrylate, Octyloxypolyethylene glycol-polypropylene glycol mono(meth)acrylate, Lauryloxypolyethylene glycol mono(meth)acrylate , Stearyloxy polyethylene glycol mono(meth)acrylate and other ether chain monomers; Acrylic acid dimers such as (meth)acrylic acid and β-carboxyethyl acrylate; Crotonic acid, maleic acid, maleic acid Carboxyl-containing monomers such as toric anhydride, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, N-glycolic acid, cinnamic acid; (meth)acrylamide, N-(n-butoxyalkyl )(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dimethylaminoalkyl( Amino-containing monomers such as meth)acrylamide; benzophenone-containing monomers such as 4-(meth)acryloxybenzophenone; acrylonitrile, methacrylonitrile, styrene, α- Methylstyrene, Vinyl Acetate, Vinyl Propionate, Vinyl Stearate, Vinyl Chloride, Vinylidene Chloride, Alkyl Vinyl Ether, Vinyl Toluene, Vinyl Pyridine, Vinyl Pyrrolidone, Icon Dialkyl Fumarate, Dialkyl Fumarate, Allyl Alcohol, Acryloyl Chloride, Methyl Vinyl Ketone, N-Acrylamidomethyl Trimethyl Ammonium Chloride, Allyl Trimethyl Chloride ammonium, dimethyl allyl vinyl ketone, etc. The ethylenically unsaturated monomer (a4) may be used alone or in combination of two or more.

As an ethylenically unsaturated monomer having two or more ethylenically unsaturated groups, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate can also be used in combination. Meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, divinylbenzene, and the like.

[Composition of the copolymerization component (a) in the first aspect] In the first aspect, the content of the alkyl acrylate (a1) is 5% by weight or more, preferably 5 to 45% by weight, based on the copolymerization component (a) %, more preferably 10 to 40% by weight, particularly preferably 12 to 35% by weight, particularly preferably 15 to 30% by weight. If the content is too small, the adhesive properties in the primary hardened state tend to decrease. When the content is too large, the adhesive properties after complete hardening tend to decrease.

In the first aspect, the content of the alkyl methacrylate (a2) is at least 5% by weight relative to the copolymerization component (a), preferably 10 to 60% by weight, more preferably 15 to 55% by weight, especially Preferably, it is 20 to 45% by weight. If the content is too small, the adhesive properties in the primary hardened state tend to decrease. When the content is too large, the adhesive properties after complete hardening tend to decrease.

In the copolymerization component (a) of the first aspect, the content ratio (a1/a2) of the alkyl acrylate (a1) to the alkyl methacrylate (a2) is 5/95 to 55/45 by weight ratio , preferably 15/85-50/50, especially 20/80-40/60.

In the first aspect, the total content of the alkyl acrylate (a1) and the alkyl methacrylate (a2) is preferably 30 to 70% by weight, more preferably 35 to 65%, based on the copolymerization component (a). % by weight, preferably 40 to 60% by weight. When the total content of the alkyl acrylate (a1) and the alkyl methacrylate (a2) is within the above numerical range, the adhesive property in the low crosslinked state of the primary hardened state becomes good, so it is preferable.

In the first aspect, the content of the hydroxyl-containing monomer (a3) is more preferably 5 to 30% by weight, further preferably 10 to 25% by weight, especially preferably 15 to 20% by weight. When the content of the hydroxyl group-containing monomer (a3) is too small, the heat-and-moisture resistance after complete curing tends to decrease. If the content of the hydroxyl group-containing monomer (a3) is too large, the adhesive property after complete hardening tends to decrease.

In the copolymerization component (a) of the first aspect, the ratio of the total content of alkyl acrylate (a1) and alkyl methacrylate (a2) to the content of hydroxyl group-containing monomer (a3) is (a1+a2)/(a3 ) is preferably 95/5-50/50 in weight ratio, more preferably 85/15-70/30, and especially preferably 80/20-75/25. When the content ratio (a1+a2)/(a3) is within the above numerical range, the adhesive properties in the primary hardened state are excellent.

When the copolymerization component (a) of the first aspect contains an ethylenically unsaturated monomer (a4), the content of the ethylenically unsaturated monomer (a4) is usually 50% by weight relative to the copolymerization component (a). % by weight or less, preferably 45% by weight or less, further preferably 40% by weight or less. When the content of the ethylenically unsaturated monomer (a4) is too large, the adhesive property at the time of low crosslinking tends to decrease.

In the first aspect, it can also be considered that the acrylic resin (A) has a structural unit based on an alkyl acrylate (a1), a structural unit based on an alkyl methacrylate (a2), and a hydroxyl-containing monomer Copolymers of the structural units of (a3). Also, in this case, the acrylic resin (A) may be based on a structural unit based on an alkyl acrylate (a1), a structural unit based on an alkyl methacrylate (a2), and a monomer based on a hydroxyl group-containing monomer (a3). In addition to the structural unit, it may further have a structural unit based on an ethylenically unsaturated monomer (a4) as needed. In this case, the ratio of the structural units based on each monomer can be determined according to the composition of the copolymerization component (a), and the same applies to the preferable aspect.

The acrylic resin (A) of the first aspect has a glass transition temperature based on dynamic viscoelasticity of -10°C or higher, preferably -5 to 20°C, more preferably 0 to 15°C, and most preferably 2 to 13°C . When the glass transition temperature based on the dynamic viscoelasticity of the acrylic resin (A) is too high, the adhesive force tends to decrease along with the decrease in the step followability of the adhesive layer or the decrease in the adhesiveness. When the glass transition temperature based on the dynamic viscoelasticity of the acrylic resin (A) is lowered, the adhesive properties at the time of low crosslinking tend to be lowered.

The glass transition temperature based on dynamic viscoelasticity can be obtained by the following measuring method. An acrylic resin solution containing only acrylic resin (A) and an organic solvent in the first aspect is prepared by adding an appropriate organic solvent. After adjusting the concentration of the acrylic resin solution, apply it on the release sheet so that the thickness after drying becomes 50 μm. Thereafter, it is dried by heat treatment at 90-105°C for 5-10 minutes, etc. to remove the organic solvent, and then attach it to a release sheet to produce acrylic resin (A) containing 99% or more. Acrylic resin sheet. Thereafter, a plurality of acrylic resin sheets were laminated to produce an acrylic resin sheet having a thickness of about 800 μm. The dynamic viscoelasticity of the produced sheet was measured under the following conditions, and the temperature at which the loss tangent (loss elastic modulus G''/storage elastic modulus G'=tanδ) reached the maximum was read as the acrylic acid based on dynamic viscoelasticity The glass transition temperature of resin (A).

(Measurement conditions of dynamic viscoelasticity) Measuring machine: Dynamic viscoelasticity measuring device (trade name: DVA-225, manufactured by Japan IT Measurement Control Co., Ltd.) Deformation mode: shear Strain: 0.1% Measuring temperature: -100～60°C Measuring frequency : 1Hz

In the first aspect, the weight average molecular weight of the acrylic resin (A) is preferably from 50,000 to 500,000, more preferably from 100,000 to 400,000, even more preferably from 150,000 to 350,000. When the weight average molecular weight of an acrylic resin (A) is too large, it exists in the tendency for a viscosity to become too high and applicability or handleability to fall. When the weight-average molecular weight of the acrylic resin (A) is too small, the cohesive force tends to decrease and the adhesive property tends to decrease. The weight average molecular weight of the acrylic resin (A) is the weight average molecular weight at the end of the production. The weight average molecular weight was measured about the acrylic resin (A) which was not heated etc. after manufacture.

The weight average molecular weight of the acrylic resin (A) is the weight average molecular weight converted from the standard polystyrene molecular weight. The weight-average molecular weight is determined by high-performance liquid chromatography (manufactured by Waters Japan, "Waters2695 (body)" and "Waters2414 (detector)") using 3 columns in series: Shodex GPC KF-806L (exclusion limit molecular weight: 2×10 ⁷ , separation range: 100 to 2×10 ⁷ , number of theoretical plates: 10,000 plates/root, filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm). The number average molecular weight can also be measured by the same method. In addition, the degree of dispersion can be obtained from the weight average molecular weight and the number average molecular weight.

The degree of dispersion (weight average molecular weight/number average molecular weight) of the acrylic resin (A) is preferably 15 or less, more preferably 10 or less, further preferably 7 or less, particularly preferably 5 or less. When the dispersion of the acrylic resin (A) is too high, the durability of the adhesive layer tends to decrease. Also, there is a tendency for foaming and the like to easily occur. When the dispersion of the acrylic resin (A) is too low, the handleability tends to decrease. The lower limit of the degree of dispersion is usually 1.1 in terms of the limit of manufacture.

[Method for producing acrylic resin (A)] In the first aspect, the acrylic resin (A) can be obtained by containing alkyl acrylate (a1), alkyl methacrylate (a2), hydroxyl-containing monomer The copolymerization component (a) of body (a3) is polymerized and produced. The copolymerization component (a) of the first aspect may further contain ethylenically unsaturated monomer (a4) of any polymerization component.

As a polymerization method of an acrylic resin (A), conventionally well-known polymerization methods, such as solution polymerization, suspension polymerization, block polymerization, and emulsion polymerization, are mentioned, for example. In view of the safety and stability of the reaction, and the point that the acrylic resin (A) can be produced with any monomer composition, solution polymerization is preferred. One example of a preferable manufacturing method of the acrylic resin (A) of the first aspect is shown below.

For example, solution polymerization can be performed by mixing or dropping the copolymerization component (a) and the polymerization initiator of the first aspect in an organic solvent. Examples of organic solvents used in the polymerization reaction include: aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as n-hexane; esters such as methyl acetate, ethyl acetate, and butyl acetate; methanol and ethanol , n-propanol, isopropanol and other aliphatic alcohols; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and other ketones; dimethyl ether, diethyl ether and other aliphatic ethers; dichloro Aliphatic halogenated hydrocarbons such as methane and dichloroethane; cyclic ethers such as tetrahydrofuran, etc. Among these organic solvents, esters and ketones are preferred, and ethyl acetate, acetone, and methyl ethyl ketone are particularly preferred. One type of organic solvent may be used alone, or two or more types may be used in combination.

As a polymerization initiator used in the polymerization reaction, an azo-based polymerization initiator or a peroxide-based polymerization initiator or the like which is a general radical polymerization initiator can be used. Examples of the azo polymerization initiator include: 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobisisobutyronitrile, (1-phenylethyl ) azodiphenylmethane, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2' -Azobis(4-methoxy-2,4-dimethylvaleronitrile) and the like.

As peroxide-based polymerization initiators, for example, benzoyl peroxide, di-tert-butyl peroxide, cumene hydroperoxide, lauryl peroxide, pivalic acid peroxide third Butyl ester, tertiary hexyl peroxypivalate, tertiary hexyl peroxyneodecanoate, diisopropyl peroxycarbonate, diisobutyryl peroxide, etc.

Among them, azo-based polymerization initiators are preferred, and 2,2'-azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylpentane nitrile). A polymerization initiator may be used alone or in combination of two or more.

The amount of the polymerization initiator used is usually 0.001 to 10 parts by weight, preferably 0.1 to 8 parts by weight, more preferably 0.5 to 6 parts by weight, and most preferably 1 to 4 parts by weight relative to 100 parts by weight of the copolymerization component (a). The weight part is more preferably 1.5 to 3 weight parts, most preferably 2 to 2.5 weight parts. When the usage-amount of a polymerization initiator is too small, since the polymerization rate of acrylic resin (A) will fall, there exists a tendency for the residual monomer to increase. Moreover, there exists a tendency for the weight average molecular weight of an acrylic resin (A) to improve. If the amount used is too large, the acrylic resin (A) tends to gel.

The polymerization conditions of the solution polymerization are not particularly limited, and the polymerization can be carried out according to previously known polymerization conditions. For example, the copolymerization component (a) and the polymerization initiator can be mixed or dropped in an organic solvent to perform polymerization.

The polymerization temperature in the polymerization reaction is usually 40 to 120°C, and is preferably 50 to 90°C in terms of stable reaction. When the polymerization temperature is too high, the acrylic resin (A) tends to be easily gelled. If the polymerization temperature is too low, the activity of the polymerization initiator decreases, so the polymerization rate decreases, and as a result, the residual monomer tends to increase. The polymerization time in the polymerization reaction is not particularly limited, and it is at least 0.5 hours from the last addition of the polymerization initiator, preferably at least 1 hour, more preferably at least 2 hours, and most preferably at least 5 hours. The polymerization reaction is preferably performed while refluxing the solvent in terms of ease of heat removal.

(Photoinitiator (B)) The photoinitiator (B) of the first aspect contains an intramolecular hydrogen abstraction type photoinitiator (b1) and an intermolecular hydrogen abstraction type photoinitiator (b2). The photoinitiator (B) of the first aspect may further contain an intramolecular hydrogen abstraction type photoinitiator (b1) and an intermolecular hydrogen abstraction type photoinitiator as long as the effect of the invention is not impaired Other photoinitiators (b3) other than (b2).

[Intramolecular hydrogen abstraction type photoinitiator (b1)] The intramolecular hydrogen abstraction type photoinitiator (b1) of the first aspect has a structure capable of generating free radicals by abstracting hydrogen from the photoinitiator itself. For example, the intramolecular hydrogen abstraction type photoinitiator (b1) may have a benzoylformate structure or the like. As the intramolecular hydrogen abstraction type photoinitiator (b1), for example, oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetyloxy-ethoxy]- Ethyl ester, methyl phenylglyoxylate, etc. Among them, in terms of crosslinking efficiency when fully hardened, oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl group having multiple crosslinking points in the molecule is preferred. -Acetyloxy-ethoxy]-ethyl ester. Commercially available products include "Omnirad MBF" and "Omnirad 754" manufactured by IGM RESINS B.V., for example.

[Intermolecular hydrogen abstraction type photoinitiator (b2)] The intermolecular hydrogen abstraction type photoinitiator (b2) of the first aspect has a structure capable of abstracting hydrogen from other than the photoinitiator itself to generate free radicals. The intermolecular hydrogen abstraction type photoinitiator (b2) may have, for example, a benzophenone structure or the like. For example, benzophenone, 4-methyl-benzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl Base-4-methoxybenzophenone, 4-(meth)acryloxybenzophenone, 4-[2-((meth)acryloxy)ethoxy]benzophenone , 4-(meth)acryloxy-4'-methoxybenzophenone, carboxymethoxymethoxybenzophenone-polyethylene glycol 250 diester, 2-benzoylbenzene Methyl formate, 4-(1,3-acryloyl-1,4,7,10,13-pentaoxotridecyl)benzophenone, etc.

Among them, 2,4,6-trimethylbenzophenone is preferable in terms of being a low-viscosity liquid and being easy to handle. Also, in terms of enabling high cross-linking, 4-(meth)acryloxybenzophenone, 4-[2-((methyl) Acryloxy)ethoxy]benzophenone, 4-(meth)acryloxy-4'-methoxybenzophenone, carboxymethoxymethoxybenzophenone-polyethylene Diol 250 diester. Commercially available products include "MBP" manufactured by Shinryo Corporation, "Omnirad BP" manufactured by IGM RESINS B.V., "Omnirad 4MBZ", "Esacure TZT" and "Omnipol BP".

[Other photoinitiators (b3)] As other photoinitiators (b3) of the first aspect, for example, diethoxyacetophenone, 2-hydroxy-2-methyl-1-benzene Propan-1-one, benzoyl dimethyl ketal, 4-(2-hydroxyethoxy) phenyl-(2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 2-Methyl-2-morpholinyl(4-thiomethylphenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)butanone , 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]acetone oligomers and other acetophenones; benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, Benzoin isobutyl ether and other benzoins; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4- Acylphosphine oxides such as trimethyl-pentylphosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

、2,4-二異丙基-9-氧硫𠮿

等。  光起始劑(B)之助劑可單獨使用1種，亦可併用2種以上。As an auxiliary agent of the photoinitiator (B) of the first aspect, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michelerone), 4,4'-Diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, ethyl 4-dimethylaminobenzoate, 4-dimethylaminobenzoic acid (n-butoxy) Ethyl ester, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethyl-9-oxothiol

, 2,4-Diisopropyl-9-oxosulfur

wait. The auxiliaries of the photoinitiator (B) may be used alone or in combination of two or more.

(Crosslinking agent (C)) The adhesive composition of the first aspect preferably further contains a crosslinking agent (C) in addition to the acrylic resin (A) and the photoinitiator (B). The crosslinking agent (C) may, for example, be an active energy ray crosslinking agent (c1) or a thermal crosslinking agent (c2). The active energy ray crosslinking agent (c1) and the thermal crosslinking agent (c2) may be used alone or in combination of two or more.

In the case where only the active energy ray crosslinking agent (c1) is contained as the crosslinking agent (C) of the first aspect, multistage hardening can be realized only by controlling the amount of active energy ray. Also, when the active energy ray crosslinking agent (c1) and the thermal crosslinking agent (c2) are contained as the crosslinking agent (C), multistage curing can also be achieved by using thermal curing and active energy ray curing together. By controlling the cross-linking reaction in the above way, the cohesion of the adhesive layer as a whole can be adjusted, and stable adhesive properties can be obtained after one hardening or after complete hardening.

[Active energy ray cross-linking agent (c1)] As the active energy ray cross-linking agent (c1) of the first aspect, for example, a polyfunctional cross-linking agent containing two or more ethylenically unsaturated groups in one molecule can be exemplified. For example, hexanediol di(meth)acrylate, butanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, (Meth)acrylate, (poly)ethylene glycol mono(meth)acrylate, (poly)butylene glycol mono(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, ( Poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, (poly)pentamethylene glycol di(meth)acrylate, (poly)hexaethylene Methyl glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate ester, trimethylolpropane tri(meth)acrylate, EO modified trimethylolpropane tri(meth)acrylate, glycerol tri(meth)acrylate, EO modified glycerol tri(meth)acrylate ester, tetramethylolmethane tri(meth)acrylate, isocyanuric acid ethylene oxide modified tri(meth)acrylate, multifunctional urethane (meth)acrylate, etc. Among them, in terms of the balance of adhesive properties after hardening, (meth)acrylates containing two ethylenically unsaturated groups are preferred, and (poly)ethylene glycol di(meth)acrylate is particularly preferred. , (poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate. The polyfunctional crosslinking agent may be used alone or in combination of two or more.

[Thermal crosslinking agent (c2)] The thermal crosslinking agent (c2) of the first aspect mainly reacts with the functional group derived from the functional group-containing monomer as the constituent monomer of the acrylic resin (A), and Can exert excellent adhesion. Examples include: isocyanate-based crosslinking agent (c2-1), epoxy-based crosslinking agent (c2-2), aziridine-based crosslinking agent (c2-3), melamine-based crosslinking agent (c2-4 ), aldehyde crosslinking agent (c2-5), amine crosslinking agent (c2-6), metal chelate crosslinking agent (c2-7). Among them, an isocyanate-based crosslinking agent (c2-1) can be suitably used from the point of improving the adhesiveness with a base material or the reactivity with an acrylic resin (A). The thermal crosslinking agent (c2) can be used alone or in combination of two or more.

Examples of the isocyanate-based crosslinking agent (c2-1) include toluene diisocyanate-based compounds such as 2,4-toluene diisocyanate and 2,6-toluene diisocyanate; 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, tetramethylxylylene diisocyanate and other xylylene diisocyanate compounds; 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate and other aromatic isocyanate compounds ; Hexamethylene diisocyanate, trimethylhexamethylene diisocyanate and other hexamethylene diisocyanate compounds, lysine diisocyanate and other aliphatic isocyanate compounds; isophorone diisocyanate and other alicyclic isocyanate compounds compounds; adducts of these isocyanate compounds and polyol compounds such as trimethylolpropane; biuret or isocyanurate forms of these isocyanate compounds, etc.

Among the isocyanate-based crosslinking agents (c2-1), it is preferable to use an aromatic isocyanate-based compound, particularly preferably a toluene diisocyanate-based compound, since it is excellent in reactivity. Moreover, it is preferable to use an aliphatic isocyanate type compound from the viewpoint of yellowing suppression, and a hexamethylene diisocyanate type compound is especially preferable.

As the epoxy-based crosslinking agent (c2-2), for example, bisphenol A-epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol di Glycidyl ether, glycerol triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether Glyceryl erythritol, diglycerol polyglycidyl ether, etc.

Examples of the aziridine-based crosslinking agent (c2-3) include: tetramethylolmethane-tri-β-aziridinyl propionate, trimethylolpropane-tri-β-aziridine propionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxyamide), N,N'-hexamethylene-1,6-bis(1- Aziridine carboxamide), etc.

As the melamine-based crosslinking agent (c2-4), for example, hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentylmelamine, Oxymethylmelamine, hexahexyloxymethylmelamine, melamine resin, etc.

As an aldehyde crosslinking agent (c2-5), glyoxal, malondialdehyde, succinaldehyde, maleic dialdehyde, glutaraldehyde, formaldehyde, acetaldehyde, benzaldehyde, etc. are mentioned, for example.

Examples of the amine-based crosslinking agent (c2-6) include hexamethylenediamine, triethylenediamine, polyethyleneimine, hexamethylenetetramine, and diethylenetriamine. , triethylenetetramine, isophorone diamine, amino resin, polyamide, etc.

Examples of the metal chelate crosslinking agent (c2-7) include acetylene of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. Acetone or acetyl acetyl ester coordination compounds, etc.

(Silane coupling agent (D)) The adhesive composition of the first aspect preferably further contains a silane coupling agent (D) as an acrylic resin (A), a photoinitiator ( Compounds other than B) and the crosslinking agent (C).

The silane coupling agent (D) is an organosilicon compound containing one or more reactive functional groups and an alkoxy group bonded to a silicon atom in its structure. Monomer type and oligomer type are mentioned as a silane coupling agent (D).

As a reactive functional group in a silane coupling agent (D), an epoxy group, (meth)acryl group, a mercapto group, a hydroxyl group, a carboxyl group, an amine group, an amide group, an isocyanate group etc. are mentioned, for example. Among them, epoxy group and mercapto group are preferable in terms of durability and secondary processability.

The content ratio of the reactive functional group in the silane coupling agent (D) is preferably 3,000 g/mol or less, more preferably 1,500 g/mol or less, further preferably 1,000 g/mol or less. When the reactive functional group is within the above numerical range, the balance between durability and secondary workability improves. The lower limit of the content ratio of the reactive functional group in the silane coupling agent (D) is 200 g/mol.

The alkoxy group bonded to the silicon atom in the silane coupling agent (D) is preferably an alkoxy group having 1 to 8 carbon atoms in terms of durability and storage stability. Among them, methoxy and ethoxy are more preferable. The silane coupling agent (D) may also have a reactive functional group and an organic functional group other than an alkoxy group bonded to a silicon atom, such as an alkyl group or a phenyl group.

As the silane coupling agent (D), for example, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, γ-shrink Glyceryloxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyl Dimethoxysilane, Methyltri(glycidyl)silane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethylsilane Oxysilane etc. Among these, γ-glycidoxypropyltrimethoxysilane is preferable in terms of heat resistance. Silane coupling agent (D) can be used alone or in combination of two or more.

(Carbodiimide Compound (E)) The adhesive composition of the first aspect preferably further contains a carbodiimide compound (E) as the acrylic resin (A) in terms of heat resistance. ), photoinitiator (B), crosslinking agent (C) and silane coupling agent (D). As the carbodiimide-based compound (E), for example, bis(2,6-diisopropylphenyl)carbodiimide, dicyclohexylcarbodiimide, diisopropylcarbodiimide, Diimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, tert-butylisopropylcarbodiimide, diphenylcarbon Monocarbodiimides such as diimide, di-tert-butylcarbodiimide, bis(dodecyl)carbodiimide, etc.; polycarbodiamides with plural carbodiimides present imine or cyclic carbodiimide, etc. Among them, in terms of heat resistance, monocarbodiimide-based compounds are preferred, and bis(2,6-diisopropylphenyl)carbodiimide is more preferred. The carbodiimide compound (E) may be used alone or in combination of two or more.

(Optional Component) The adhesive composition of the first aspect may contain an adhesive as another optional component as needed. The adhesive composition of the first aspect may contain previously known additives such as crosslinking accelerators, antistatic agents, adhesion imparting agents, and functional pigments.

(Composition of Adhesive Composition) In the first aspect, the content of the acrylic resin (A) is preferably at least 80% by weight, more preferably 90 to 99.9% by weight, and still more preferably Preferably, it is 92 to 99.9% by weight. If the content of the acrylic resin (A) is within the above numerical range, it is easy to obtain excellent adhesive properties in a low crosslinked state after primary curing.

In the first aspect, the content of the photoinitiator (B) is preferably 0.1-5.0 parts by weight, more preferably 0.5-4.0 parts by weight, and even more preferably 100 parts by weight of the acrylic resin (A). 1.0 to 3.0 parts by weight. When the content of the photoinitiator (B) is within the above numerical range, sufficient curability can be obtained when fully cured.

In the first aspect, the content of the intramolecular hydrogen abstraction photoinitiator (b1) is preferably 0.1-5.0 parts by weight, more preferably 0.5-3.0 parts by weight relative to 100 parts by weight of the acrylic resin (A) . If the content of the hydrogen-abstracting photoinitiator (b1) in the molecule is too much, it tends to change color after prolonged exposure to heat and humidity. If the content of the intramolecular hydrogen-abstracting photoinitiator (b1) is too small, the degree of crosslinking will not increase, resulting in poor adhesive properties during primary curing or durability after complete curing.

In the first aspect, the content of the intermolecular hydrogen abstraction type photoinitiator (b2) is preferably 0.1-3.0 parts by weight, more preferably 0.5-2.0 parts by weight relative to 100 parts by weight of the acrylic resin (A) . If the content of intermolecular hydrogen abstraction type photoinitiator (b2) is too much, there is a tendency to bleed out and cause poor durability. If the content of the intermolecular hydrogen-abstracting photoinitiator (b2) is too small, the degree of crosslinking will not increase, resulting in poor adhesive properties during primary curing or durability after complete curing.

In the first aspect, when the photoinitiator (B) contains other photoinitiator (b3), the content of the photoinitiator (b3) is 100 parts by weight relative to the acrylic resin (A). It is preferably at most 2.0 parts by weight, more preferably at most 1.0 parts by weight.

In the first aspect, when the adhesive composition contains a crosslinking agent (C), the content of the crosslinking agent (C) is usually preferably 20 parts by weight relative to 100 parts by weight of the acrylic resin (A) Below, it is more preferable that it is 0.001-10 weight part, and it is still more preferable that it is 0.1-7.5 weight part. If the content of the crosslinking agent (C) is too high, the adhesive force tends to decrease. When the content of the crosslinking agent (C) is too small, durability tends to decrease.

In the first aspect, when the adhesive composition contains the active energy ray crosslinking agent (c1), the content of the active energy ray crosslinking agent (c1) is usually 100 parts by weight relative to the acrylic resin (A), Preferably it is 0.01-20 weight part, More preferably, it is 0.1-10 weight part, More preferably, it is 0.5-7.5 weight part. If the content of the active energy ray crosslinking agent (c1) is too small, sufficient durability may not be obtained due to insufficient cohesive force. When the content of the active energy ray crosslinking agent (c1) is too large, the adhesive property at the time of primary curing tends to decrease.

In the first aspect, when the adhesive composition contains a thermal crosslinking agent (c2), the content of the thermal crosslinking agent (c2) is usually 0.001 parts by weight relative to 100 parts by weight of the acrylic resin (A). -5 parts by weight, more preferably 0.02-1 part by weight, still more preferably 0.05-0.5 parts by weight. If the content of the thermal crosslinking agent (c2) is too small, the cohesive force will be insufficient and the adhesive properties will tend to decrease during primary hardening. If the content of the thermal crosslinking agent (c2) is too high, the adhesive force tends to decrease when fully hardened.

In the first aspect, when the adhesive composition contains the silane coupling agent (D), the content of the silane coupling agent (D) is preferably 0.001 to 3 parts by weight relative to 100 parts by weight of the acrylic resin (A) part, more preferably 0.005 to 1 part by weight, still more preferably 0.01 to 0.5 part by weight, especially preferably 0.015 to 0.3 part by weight. If the content of the silane coupling agent (D) is too small, it tends to be difficult to obtain the effect of improving durability. If the content of the silane coupling agent (D) is too high, the adhesive force tends to decrease due to effects such as bleeding.

In the first aspect, when the adhesive composition contains the carbodiimide compound (E), the content of the carbodiimide compound (E) is 100 parts by weight of the acrylic resin (A) , preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, further preferably 0.2 to 2 parts by weight, especially preferably 0.3 to 1 part by weight. If the content of the carbodiimide compound (E) is too small, the thermal stability of the acrylic resin (A) tends to decrease. When the content of the carbodiimide-based compound (E) is too high, durability tends to decrease due to effects such as bleeding.

In the first aspect, when other adhesives or additives are added to the adhesive combination, the content of the other adhesives or additives is preferably 10 parts by weight or less with respect to 100 parts by weight of the acrylic resin (A), More preferably, it is 5 parts by weight or less.

(Preparation of Adhesive Composition) By mixing acrylic resin (A), photoinitiator (B), optional crosslinking agent (C), silane coupling agent (D), carbodiimide compound (E) Other optional ingredients are mixed to obtain the adhesive composition of the first aspect. The mixing method is not particularly limited, and the following various methods can be used: a method of mixing the ingredients at one time; a method of mixing the remaining ingredients one at a time or sequentially after mixing any of the ingredients.

(Applications) The adhesive composition of the first aspect can be suitably used as an adhesive for a multistage curable adhesive sheet that is hardened in a plurality of stages. According to the adhesive composition of the first aspect, excellent adhesive properties can also be obtained in a low-crosslinked state after primary curing. Furthermore, after it is completely cured, it not only exhibits adhesive properties such as usual adhesive force, but also exhibits excellent durability when laminating members of various types and shapes such as polarizing plates and glass.

The adhesive composition of the first aspect has excellent adhesive properties such as low tactile tack and high constant load holding power in a low crosslinked state after primary curing, thereby improving workability and reliability. Therefore, it can be suitably used especially for the use of the adhesive agent used for a touch panel, an image display apparatus, etc., or an adhesive sheet.

<Adhesive> The adhesive of the first aspect is obtained by cross-linking the adhesive composition of the first aspect. By crosslinking (curing) the adhesive composition of the present invention, the acrylic resin (A) contained in the adhesive composition forms a crosslinked structure in at least one of intramolecular and intermolecular. As a result, the adhesive composition of the present invention is crosslinked to become the adhesive of the first aspect. In the case where the acrylic resin (A) has an active energy ray crosslinkable structural site, a crosslinked structure can be formed by irradiation with active energy rays.

The adhesive of the first aspect exhibits multi-stage hardening that can be hardened in multiple stages. The adhesive of the first aspect is in a low cross-linking state by primary curing before complete curing. Complete hardening and primary hardening may not be clearly distinguished, for example, they can be distinguished based on the difference in gel fraction or dynamic viscoelasticity.

In any one of the primary hardening step and the complete hardening step, the hardening method is not particularly limited, and any one of heating or active energy ray irradiation may be used. In addition, one hardening step may be performed in plural times, or multi-step hardening may be performed in order to make it into a fully hardened state. The adhesive of the first aspect has excellent adhesive properties after primary curing, so it can be suitably used for lamination of optical components constituting touch panels or image display devices.

The adhesive of the first aspect can be considered to contain at least a cross-linked product of the acrylic resin (A) of the first aspect. The cross-linked product may be a partially cross-linked product in which at least a part of the acrylic resin (A) is partially cross-linked, or may be a fully cross-linked product in which all of the acrylic resin (A) is fully cross-linked. Moreover, the adhesive agent of a 1st aspect may contain both the partially crosslinked thing and the fully crosslinked thing of an acrylic resin (A).

<Adhesive Sheet> The adhesive sheet of the first aspect has an adhesive layer containing the adhesive of the first aspect. The adhesive sheet of the first aspect can exhibit multi-stage hardening in which the adhesive layer hardens in plural stages.

An adhesive sheet can be produced by disposing an adhesive layer containing the adhesive of the first aspect on a base sheet. Moreover, a double-sided adhesive sheet can be produced by providing an adhesive layer on a release sheet. Furthermore, an adhesive layer is formed on the release sheet instead of the substrate sheet, and the release sheet is attached to the adhesive layer on the opposite side, thereby also making a double-sided adhesive sheet without a substrate. It is also possible to further form an adhesive layer on the formed adhesive layer, and further form a thick-film adhesive layer. When the obtained adhesive sheet or double-sided adhesive sheet is used, the release sheet is peeled off from the adhesive layer for use.

As a method of producing the adhesive sheet of the first aspect, methods such as the following (i) and (ii) may be mentioned, for example. (i) A method of producing an adhesive sheet after applying a coating liquid obtained by dissolving the adhesive composition of the first aspect in a solvent. (ii) A method of producing an adhesive sheet after melting the adhesive composition of the first aspect by heating.

The method of (i) will be described. When preparing an adhesive sheet after applying a coating liquid obtained by dissolving the adhesive composition of the first aspect in a solvent, the amount of the adhesive composition containing the first aspect is adjusted with an appropriate organic solvent. The concentration of the coating solution is directly applied to the substrate sheet. Thereafter, it is dried by, for example, heat treatment at 80 to 105° C. for 0.5 to 10 minutes, and attached to a base material sheet or a release sheet. Thereafter, the adhesive composition is crosslinked (hardened) by active energy ray irradiation or aging to produce an adhesive sheet having an adhesive layer containing the adhesive.

As an organic solvent used for concentration adjustment, what was mentioned as the organic solvent used for the polymerization reaction of an acrylic resin (A) is mentioned. The concentration of the adhesive composition is usually 20 to 60% by weight, preferably 30 to 50% by weight, based on solid content.

The method of (ii) will be described. When the adhesive composition of the first aspect is melted by heating to form an adhesive sheet, by applying it to one or both sides of the base sheet in a melted state, and then cooling method or a method of extruding onto a base sheet through a T-die or the like for lamination, the adhesive layer is formed on one side or both sides of the base sheet so as to have a desired thickness. Then, if necessary, attach a release sheet to the adhesive layer, thereby producing an adhesive sheet.

In addition, after forming the adhesive layer on the base sheet, if necessary, it is subjected to active energy ray irradiation treatment, and aging is performed, whereby an adhesive sheet having an adhesive layer formed by hardening (crosslinking) the adhesive composition can be produced. material. Furthermore, the adhesive layer is formed on the release sheet, and the release sheet is attached to the adhesive layer on the opposite side, so that a double-sided adhesive sheet without a substrate can also be produced. When the obtained adhesive sheet or double-sided adhesive sheet is used, the release sheet is peeled off from the adhesive layer for use.

As the base sheet, for example, polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate/isophthalic acid Polyester resins such as ethylene glycol copolymer; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyvinyl fluoride, polyvinylidene fluoride, polyfluoroethylene, etc. Polyfluoroethylene resin; nylon 6, nylon 6,6 and other polyamides; polyvinyl chloride, polyvinyl chloride/vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyethylene Vinyl polymers such as alcohol and vinylon; Cellulose resins such as cellulose triacetate and celluloid; Acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate Resin; polystyrene; polycarbonate; polyarylate; polyimide and other synthetic resin sheets; aluminum, copper, iron and other metal foils; high-grade paper, cellophane and other paper; including glass fiber, natural fiber, synthetic fiber, etc. woven or non-woven fabrics. These base sheets may be used as a single layer body or as a multilayer body in which two or more types are laminated. Among them, a synthetic resin sheet is preferable in terms of weight reduction and the like.

As the release sheet, for example, those obtained by subjecting various synthetic resin sheets, paper, woven fabrics, non-woven fabrics, etc. to the base sheet to a release treatment can be used. As the release sheet, for example, a silicon-based release sheet is preferably used.

The application method of the adhesive composition is not particularly limited. For example, methods such as roll coating, die coating, gravure coating, chipped wheel coating, slit coating, and screen printing may be mentioned.

As active energy rays, rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, and infrared rays; electromagnetic waves such as X-rays and γ-rays; electron beams; proton beams; neutron rays, etc., can be used. Curing using ultraviolet rays is preferred in terms of curing speed, availability of irradiation equipment, price, and the like.

Regarding the gel fraction before the adhesive layer of the adhesive sheet is completely hardened, regardless of the shape of the adherend, it is easy to stick and the adhesive layer can hold the adherend after sticking. , preferably 0.1 to 60% by weight, more preferably 1 to 50% by weight, especially preferably 5 to 45% by weight.

With regard to the gel fraction after the adhesive layer of the adhesive sheet is completely hardened, it is preferably 50 to 95% by weight, more preferably 55 to 90% by weight, and especially preferably 60 to 85% by weight. When the gel fraction is too low, durability tends to decrease due to decreased cohesive force. If the gel fraction is too high, there is a tendency for the adhesive force to decrease due to the increase in the cohesive force.

The gel fraction can be appropriately adjusted by the following method, for example.・Adjust the dose of active energy rays.・Adjust the content of the active energy ray cross-linking structure in the acrylic resin (A).・Adjust the type or amount of photoinitiator (B) and crosslinking agent (C).

The gel fraction serves as a standard for the degree of crosslinking (degree of hardening), and can be calculated, for example, by the following method. That is, an adhesive sheet formed by wrapping a polymer sheet (such as a polyethylene terephthalate (PET) film, etc.) as a base material with a 200 mesh SUS wire mesh to form an adhesive layer (not shown For those with a release sheet), dip in toluene maintained at 23°C for 24 hours, and use the weight percentage of the insoluble adhesive components remaining in the wire mesh as the gel fraction. However, it is calculated by subtracting the weight of the substrate from the weight before and after dissolving toluene.

The thickness of the adhesive layer of the adhesive sheet is usually preferably from 50 to 3000 μm, more preferably from 75 to 1000 μm, and especially preferably from 100 to 350 μm. When the thickness of the adhesive layer is too thin, the impact absorption tends to decrease. When the thickness of the adhesive layer is too thick, for example, when sticking to an optical member, the overall thickness increases and the practicability tends to decrease.

The thickness of the adhesive layer is obtained by subtracting the measured value of the thickness of the constituent members other than the adhesive layer from the measured value of the thickness of the entire laminate including the adhesive layer using "ID-C112B" manufactured by Mitutoyo Co., Ltd. value.

The adhesive layer of the adhesive sheet according to the first aspect preferably has a haze value of 2% or less when the thickness of the adhesive layer is 100 μm, more preferably 0-1.5%, especially preferably 0-1% . When the haze value is too high, the pressure-sensitive adhesive layer tends to become white and reduce transparency. The haze value is measured by using HAZE MATER NDH4000 (manufactured by Nippon Denshoku Industries Co., Ltd.) to measure the diffuse transmittance and total light transmittance, and substitute the obtained values of diffuse transmittance (DT) and total light transmittance (TT) into the following [Formula 1] and calculated. This machine complies with JIS K7361-1. Haze value (%)＝(DT/TT)×100・・・[Formula 1]

In the first aspect, an optical member with an adhesive layer attached can be obtained by forming an adhesive laminated layer on the optical member. For example, after adhering the adhesive layer of the adhesive sheet of the first aspect with the adhesive layer formed on the release sheet to the optical member, the release sheet is peeled off, thereby obtaining an optical device with an adhesive layer. member. Moreover, optical members can also be bonded together using the said double-sided adhesive sheet.

The optical member may, for example, be a member constituting a touch panel or an image display device. For example, display (organic EL (Electroluminescence, electroluminescence), liquid crystal), transparent conductive film substrate (ITO (Indium Tin Oxides, indium tin oxide) substrate), protective film (glass), transparent antenna (film), Transparent wiring, etc.

Preferred implementations of the first aspect described above include the following [A1] to [A7], but are not limited thereto. [A1] An adhesive composition characterized in that it contains an acrylic resin (A) and a photoinitiator (B), and the acrylic resin (A) is a polymerization product of the following copolymerization component (a), The above-mentioned acrylic resin (A) has a glass transition temperature based on dynamic viscoelasticity of -10°C or higher, and the above-mentioned copolymerization component (a) contains at least an alkyl acrylate having a glass transition temperature of -30 to 50°C when forming a homopolymer (a1), an alkyl methacrylate (a2) having a glass transition temperature of -10 to 120°C when forming a homopolymer, and a hydroxyl-containing monomer (a3), the above-mentioned alkyl acrylate (a1) and the above-mentioned methyl The weight ratio of the alkyl acrylate (a2) is 5/95 to 55/45, and the total content of the above-mentioned alkyl acrylate (a1) and the above-mentioned alkyl methacrylate (a2) relative to the copolymerization component (a) is 30 to 70% by weight, the photoinitiator (B) contains an intramolecular hydrogen abstraction type photoinitiator (b1) and an intermolecular hydrogen abstraction type photoinitiator (b2). [A2] The adhesive composition as described in [A1], further comprising a crosslinking agent (C). [A3] The adhesive composition described in [A1] or [A2], wherein the acrylic resin (A) has a weight average molecular weight of 50,000 to 500,000. [A4] An adhesive obtained by crosslinking the adhesive composition described in any one of [A1] to [A3]. [A5] The adhesive described in [A4], wherein the crosslinking is performed by irradiation of active energy rays. [A6] An adhesive sheet having an adhesive layer comprising the adhesive described in [A4] or [A5]. [A7] The adhesive sheet as described in [A6], wherein the above-mentioned adhesive layer is multistage hardening that is hardened in a plurality of stages.

[Second Form] Hereinafter, although the embodiment of the second aspect of the present invention will be described in detail, they are disclosed as representative examples of preferred implementation aspects.

<Adhesive composition> The adhesive composition of the second aspect contains an acrylic resin (A) and a photoinitiator (B). In addition to the acrylic resin (A) and the photoinitiator (B), the adhesive composition of the second aspect may further contain a crosslinking agent (C), a silane coupling agent (D), a carbodiamide Amine compound (E), and other optional components. Hereinafter, each component is demonstrated sequentially.

(Acrylic resin (A)) The acrylic resin (A) of the second aspect is a polymerization product of the specific copolymerization component (a). The copolymerization component (a) is a general term for monomer components having a polymerizable double bond. The copolymerization component (a) does not contain a polymerization initiator or a polymerization solvent.

The specific copolymerization component (a) of the second aspect contains at least an alkyl (meth)acrylate (a1) having an alkyl group having 12 or less carbon atoms and having a homopolymer glass transition temperature of -20 to 120°C and A hydroxyalkyl monomer (a2) containing an alkyl chain, a hydroxyl group and an ethylenically unsaturated group. The copolymerization component (a) of the second aspect may further contain an ethylenically unsaturated monomer (a3) other than the alkyl (meth)acrylate (a1) and the hydroxyalkyl monomer (a2) if necessary.

[Alkyl (meth)acrylate (a1)] The alkyl (meth)acrylate (a1) of the second aspect has an alkyl group having 12 or less carbon atoms. The number of carbon atoms in the alkyl group of the alkyl (meth)acrylate (a1) is preferably 8 or less, more preferably 4 or less. When the carbon number of the alkyl group of the alkyl (meth)acrylate (a1) is below the above upper limit, it is easy to obtain excellent adhesive properties in a low crosslinked state after primary curing.

The alkyl (meth)acrylate (a1) of the second aspect is a monomer whose homopolymer has a glass transition temperature (hereinafter referred to as "Tg") of -20 to 120°C. The Tg of the homopolymer of the alkyl (meth)acrylate (a1) of the second aspect is preferably 0-105°C, more preferably 5-70°C. If the Tg of the homopolymer of the alkyl (meth)acrylate (a1) is within the above numerical range, it is possible to obtain an adhesive with excellent adhesion when it is attached to an adherend of a complex shape to which a strong stress is applied. Sheet.

The homopolymer of alkyl (meth)acrylate (a1) is the homopolymer of alkyl (meth)acrylate (a1). As Tg of the homopolymer of alkyl (meth)acrylate (a1), the standard analysis value described in "POLYMER HANDBOOK" published by Wiley etc. can be used.

As the alkyl (meth)acrylate (a1) of the second aspect, for example, methyl acrylate (Tg: 8°C), tert-butyl acrylate (Tg: 41°C), cyclohexyl acrylate ( Tg: 15°C), isomethacrylate (Tg: 97°C), methyl methacrylate (Tg: 105°C), ethyl methacrylate (Tg: 65°C), n-butyl methacrylate (Tg : 20°C), isobutyl methacrylate (Tg: 48°C), tertiary butyl methacrylate (Tg: 107°C), 2-ethylhexyl methacrylate (Tg: -10°C), formazan Cyclohexyl acrylate (Tg: 66°C), etc. Among them, methyl acrylate, methyl methacrylate, ethyl methacrylate, and isobutyl methacrylate are preferable in terms of adhesive properties. Alkyl (meth)acrylates (a1) may be used alone or in combination of two or more.

[Hydroxyalkyl Monomer (a2)] The hydroxyalkyl monomer (a2) of the second aspect contains an alkyl chain, a hydroxyl group, and an ethylenically unsaturated group. The hydroxyalkyl monomer (a2) of the second aspect can be represented by the following general formula, for example. CH ₂ =CHR-XY-OH In the formula, R is a hydrogen atom or a methyl group, X is an oxygen atom, COO or CONH, and Y is a linear or branched alkyl chain.

The average carbon number of the alkyl chain of the hydroxyalkyl monomer (a2) in the copolymerization component (a) of the second aspect is 2.1 or more, preferably 2.1-8.0, more preferably 2.4-6.0, especially 2.6 ~4.0. When the average carbon number of the alkyl chain of a hydroxyalkyl monomer (a2) is too small, the reliability at the time of complete hardening will tend to fall. When the average number of carbon atoms in the alkyl chain of the hydroxyalkyl monomer (a2) is too large, the adhesive property after primary curing tends to decrease.

Here, when the copolymerization component (a) of the second aspect contains a hydroxyalkyl monomer (a2), the average carbon number of the alkyl chain of the hydroxyalkyl monomer (a2) is set as the The carbon number itself of the alkyl chain of the base monomer (a2). On the other hand, when the copolymerization component (a) of the second aspect contains two or more plural hydroxyalkyl monomers (a2), the average carbon number of the alkyl chain of the hydroxyalkyl monomer (a2) Let it be the weight average of the carbon number of the alkyl chain of the hydroxyalkyl monomer (a2) in the copolymerization component (a) of the 2nd aspect.

For example, the copolymerization component (a) in the second aspect contains two kinds of monomer s of w _s weight part and w _t weight part of monomer t with respect to 100 weight parts of copolymerization component (a) as hydroxyalkyl monomers. In the case of the body (a2), the average carbon number n of the alkyl chain of the hydroxyalkyl monomer (a2) in the copolymerization component (a) of the second aspect can be obtained as follows.

n=n _s ×w _s /(w _s +w _t )+n _t ×w _t /(w _s +w _t ) Here, n _s is the carbon number of the alkyl chain of the monomer s, n _t is the carbon number of the monomer t The number of carbons in the alkyl chain. When the copolymerization component (a) of the second aspect contains three or more hydroxyalkyl monomers (a2), the hydroxyalkyl monomer (a2) in the copolymerization component (a) can also be calculated by the same formula The average carbon number of the alkyl chain.

As the hydroxyalkyl monomer (a2) of the second aspect, for example, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxyl (meth)acrylate Butyl, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 7-hydroxyheptyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, etc. contain primary hydroxyl groups (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2,2-dimethyl 2-hydroxyethyl (meth)acrylate, etc. Hydroxyalkyl (meth)acrylate monomers such as (meth)acrylates of primary or tertiary hydroxyl groups; N-(2-hydroxyethyl)(meth)acrylamide, N-(4-hydroxybutyl )(meth)acrylamide, N-(6-hydroxyhexyl)(meth)acrylamide and other hydroxyalkyl(meth)acrylamide; 2-hydroxyethyl vinyl ether, 4-hydroxybutyl Hydroxyalkyl vinyl ethers such as vinyl ether and 6-hydroxyhexyl vinyl ether. The hydroxyalkyl monomer (a2) may be used alone or in combination of two or more. Among them, the (meth)acrylate containing primary hydroxyl is preferred, especially the combined use of 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate or the use of (meth)acrylate alone ) 4-hydroxybutyl acrylate.

[Ethylenic unsaturated monomer (a3)] The copolymerization component (a) of the second aspect may further contain other copolymerizable monomers other than alkyl (meth)acrylate (a1) and hydroxyalkyl monomer (a2) The ethylenically unsaturated monomer (a3). Other copolymerizable ethylenically unsaturated monomers (a3) include, for example, alkyl (meth)acrylates such as n-butyl acrylate and 2-ethylhexyl (meth)acrylate (among them, (meth)acrylate base) alkyl acrylate (except a1)); phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenyldiethylene glycol (meth)acrylate ester, phenoxypolyethylene glycol (meth)acrylate, phenoxypolyethylene glycol-polypropylene glycol-(meth)acrylate, o-phenylphenoxyethyl (meth)acrylate, nonyl Aromatic ring-containing monomers such as phenol ethylene oxide adduct (meth)acrylate; cyclohexyloxyalkyl (meth)acrylate, tertiary butylcyclohexyloxyethyl (meth)acrylate, Alicyclic monomers such as isomethacrylate and dicyclopentyl (meth)acrylate; 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-butoxydiethylene glycol (meth)acrylate, methoxydiethylene glycol ( Meth)acrylate, Methoxytriethylene glycol (meth)acrylate, Ethoxydiethylene glycol (meth)acrylate, Methoxydipropylene glycol (meth)acrylate, Methoxy poly Ethylene glycol (meth)acrylate, octyloxypolyethylene glycol-polypropylene glycol mono(meth)acrylate, dodecyloxypolyethylene glycol mono(meth)acrylate, stearyloxy poly Ether chain monomers such as ethylene glycol mono(meth)acrylate; (meth)acrylic acid, β-carboxyethyl acrylate and other acrylic acid dimers, crotonic acid, maleic acid, maleic anhydride, fumaric acid , citraconic acid, glutaconic acid, itaconic acid, N-glycolic acid, cinnamic acid and other carboxyl-containing monomers; polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, hexanoic acid Hydroxyl-containing monomers other than hydroxyalkyl monomers (a2) such as lactone-modified (meth)acrylate 2-hydroxyethyl acrylate and 2-acryloxyethyl-2-hydroxyethyl phthalic acid; (Meth)acrylamide, N-(n-butoxyalkyl)(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide amide-containing monomers such as acrylamide, N,N-dimethylaminoalkyl (meth)acrylamide; 4-(meth)acryloxybenzophenone and other benzophenone-containing Ketone monomers; acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl acetate, vinyl propionate, vinyl stearate, vinyl chloride, vinylidene chloride, alkyl vinyl ether , vinyl toluene, vinyl pyridine, vinyl pyrrolidone, dialkyl itaconate, dialkyl fumarate, allyl alcohol, acryl chloride, methyl vinyl ketone, N-acrylamide Methyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethylallyl vinyl ketone, and the like. The ethylenically unsaturated monomer (a3) may be used alone or in combination of two or more.

As an ethylenically unsaturated monomer having two or more ethylenically unsaturated groups, it can also be used in combination: ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol diacrylate (meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, divinylbenzene, and the like.

[Composition of the copolymerization component (a) of the second aspect] In the second aspect, the content of the alkyl (meth)acrylate (a1) is 30% by weight or more based on 100% by weight of the copolymerization component (a). The content of the alkyl (meth)acrylate (a1) is preferably from 35 to 75% by weight, more preferably from 40 to 65% by weight, and still more preferably from 45 to 60% by weight. When the content of the alkyl (meth)acrylate (a1) is too small, the adhesive properties in the primary hardened state tend to decrease. When the content of the alkyl (meth)acrylate (a1) is too large, the adhesive properties after complete curing tend to decrease.

In the second aspect, the content of the hydroxyalkyl monomer (a2) is at least 0.1% by weight, preferably 0.1 to 30% by weight, more preferably 5 to 30% by weight, based on 100% by weight of the copolymerization component (a) , and more preferably 10 to 25% by weight. When the content of the hydroxyalkyl monomer (a2) is too small, the adhesive properties in the primary hardened state tend to decrease. When the content of the hydroxyalkyl monomer (a2) is too large, the adhesive properties after complete curing tend to decrease.

In the copolymerization component (a) of the second aspect, the content ratio (a1/a2) of the alkyl (meth)acrylate (a1) to the hydroxyalkyl monomer (a2) is preferably 95/5 by weight ~50/50, more preferably 85/15~70/30, especially preferably 80/20~75/25. When the content ratio (a1/a2) is within the above numerical range, the adhesive properties in the primary hardened state are excellent.

When the copolymerization component (a) of the second aspect contains the ethylenically unsaturated monomer (a3), the content of the ethylenically unsaturated monomer (a3) is usually 50% by weight relative to the copolymerization component (a). % by weight or less, preferably 40% by weight or less, further preferably 35% by weight or less. When the content of the ethylenically unsaturated monomer (a3) is too large, the adhesive property at the time of low crosslinking tends to decrease.

The acrylic resin (A) of the second aspect can also be regarded as a copolymer having a structural unit based on an alkyl (meth)acrylate (a1) and a structural unit based on a hydroxyalkyl monomer (a2). Also, in this case, the acrylic resin (A) may be further modified as necessary in addition to the structural unit based on the alkyl (meth)acrylate (a1) and the structural unit based on the hydroxyalkyl monomer (a2). It has a structural unit based on an ethylenically unsaturated monomer (a3). In this case, the ratio of the structural units based on each monomer can be determined according to the composition of the copolymerization component (a), and the same applies to the preferable aspect.

The glass transition temperature of the acrylic resin (A) of the second aspect based on dynamic viscoelasticity is above -10°C, preferably -5 to 20°C, more preferably 0 to 15°C, most preferably 2 to 13°C . When the glass transition temperature based on the dynamic viscoelasticity of the acrylic resin (A) is too high, the adhesive force tends to decrease along with the decrease in the step followability of the adhesive layer or the decrease in the adhesiveness. When the glass transition temperature based on the dynamic viscoelasticity of the acrylic resin (A) is lowered, the adhesive properties at the time of low crosslinking tend to be lowered.

The glass transition temperature based on dynamic viscoelasticity can be obtained by the following measuring method. An acrylic resin solution containing only acrylic resin (A) and an organic solvent is prepared by using an appropriate organic solvent. After adjusting the concentration of the acrylic resin solution, apply it on the release sheet so that the thickness after drying becomes 50 μm. Afterwards, it is dried by heat treatment at 90-105°C for 5-10 minutes to remove the organic solvent, and then attach it to a release sheet to produce an acrylic resin sheet containing more than 99% of acrylic resin material. Thereafter, a plurality of acrylic resin sheets were laminated to produce an acrylic resin sheet having a thickness of about 800 μm. The dynamic viscoelasticity of the prepared sheet was measured under the following conditions, and the temperature at which the loss tangent (loss elastic modulus G''/storage elastic modulus G'=tanδ) reached the maximum was read as the value based on dynamic viscoelasticity Glass transition temperature of acrylic resin (A).

(Measurement conditions of dynamic viscoelasticity) Measuring machine: Dynamic viscoelasticity measuring device (trade name: DVA-225, manufactured by Japan IT Measurement Control Co., Ltd.) Deformation mode: shear Strain: 0.1% Measuring temperature: -100～60°C Measuring frequency : 1Hz

In the second aspect, the weight average molecular weight of the acrylic resin (A) is preferably from 50,000 to 500,000, more preferably from 100,000 to 400,000, even more preferably from 150,000 to 350,000. When the weight average molecular weight of an acrylic resin (A) is too large, it exists in the tendency for a viscosity to become too high and applicability or handleability to fall. When the weight-average molecular weight of the acrylic resin (A) is too small, the cohesive force tends to decrease and the adhesive property tends to decrease. The weight average molecular weight of the acrylic resin (A) is the weight average molecular weight at the end of the production. The weight average molecular weight was measured about the acrylic resin (A) which was not heated etc. after manufacture.

The weight average molecular weight of the acrylic resin (A) is the weight average molecular weight converted from the standard polystyrene molecular weight. The weight-average molecular weight is determined by high-performance liquid chromatography (manufactured by Waters Japan, "Waters2695 (body)" and "Waters2414 (detector)") using 3 columns in series: Shodex GPC KF-806L (exclusion limit molecular weight: 2×10 ⁷ , separation range: 100 to 2×10 ⁷ , number of theoretical plates: 10,000 plates/root, filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm). The number average molecular weight can also be measured by the same method. In addition, the degree of dispersion can be obtained from the weight average molecular weight and the number average molecular weight.

The degree of dispersion (weight average molecular weight/number average molecular weight) of the acrylic resin (A) is preferably 15 or less, more preferably 10 or less, further preferably 7 or less, particularly preferably 5 or less. When the dispersion of the acrylic resin (A) is too high, the durability of the adhesive layer tends to decrease. Also, there is a tendency for foaming and the like to easily occur. When the dispersion of the acrylic resin (A) is too low, the handleability tends to decrease. The lower limit of the degree of dispersion is usually 1.1 in terms of the limit of manufacture.

[Method for producing acrylic resin (A)] In the second aspect, the acrylic resin (A) can be obtained by making The copolymerization component (a) is polymerized and produced. The copolymerization component (a) of the second aspect may further contain ethylenically unsaturated monomer (a3) of any polymerization component.

As a polymerization method of an acrylic resin (A), conventionally well-known polymerization methods, such as solution polymerization, suspension polymerization, block polymerization, and emulsion polymerization, are mentioned, for example. In view of the safety and stability of the reaction, and the point that the acrylic resin (A) can be produced with any monomer composition, solution polymerization is preferred. One example of a preferable manufacturing method of the acrylic resin (A) of the second aspect is shown below.

For example, solution polymerization can be performed by mixing or dropping the copolymerization component (a) and the polymerization initiator of the second aspect in an organic solvent. Examples of organic solvents used in the polymerization reaction include aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as n-hexane; esters such as methyl acetate, ethyl acetate, and butyl acetate; methanol and ethanol , n-propanol, isopropanol and other aliphatic alcohols; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and other ketones; dimethyl ether, diethyl ether and other aliphatic ethers; dichloro Aliphatic halogenated hydrocarbons such as methane and dichloroethane; cyclic ethers such as tetrahydrofuran, etc. Among these organic solvents, esters and ketones are preferred, and ethyl acetate, acetone, and methyl ethyl ketone are particularly preferred. One type of organic solvent may be used alone, or two or more types may be used in combination.

As a polymerization initiator used in the polymerization reaction, an azo-based polymerization initiator or a peroxide-based polymerization initiator or the like which is a general radical polymerization initiator can be used. Examples of the azo polymerization initiator include: 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobisisobutyronitrile, (1-phenylethyl ) azodiphenylmethane, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2' -Azobis(4-methoxy-2,4-dimethylvaleronitrile) and the like.

As peroxide-based polymerization initiators, for example, benzoyl peroxide, di-tert-butyl peroxide, cumene hydroperoxide, lauryl peroxide, pivalic acid peroxide third Butyl ester, tertiary hexyl peroxypivalate, tertiary hexyl peroxyneodecanoate, diisopropyl peroxycarbonate, diisobutyryl peroxide, etc.

Among them, azo-based polymerization initiators are preferred, and 2,2'-azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylpentane nitrile). A polymerization initiator may be used alone or in combination of two or more.

The amount of the polymerization initiator used is usually 0.001 to 10 parts by weight, preferably 0.1 to 8 parts by weight, more preferably 0.5 to 6 parts by weight, and most preferably 1 to 4 parts by weight relative to 100 parts by weight of the copolymerization component (a). The weight part is more preferably 1.5 to 3 weight parts, most preferably 2 to 2.5 weight parts. When the usage-amount of a polymerization initiator is too small, since the polymerization rate of acrylic resin (A) will fall, there exists a tendency for the residual monomer to increase. Moreover, there exists a tendency for the weight average molecular weight of an acrylic resin (A) to improve. If the amount used is too large, the acrylic resin (A) tends to gel.

The polymerization conditions of the solution polymerization are not particularly limited, and the polymerization can be carried out according to previously known polymerization conditions. For example, the copolymerization component (a) and the polymerization initiator can be mixed or dropped in an organic solvent to perform polymerization.

The polymerization temperature in the polymerization reaction is usually 40 to 120°C, but it is preferably 50 to 90°C in terms of stable reaction. When the polymerization temperature is too high, the acrylic resin (A) tends to be easily gelled. If the polymerization temperature is too low, the activity of the polymerization initiator decreases, so the polymerization rate decreases, and as a result, the residual monomer tends to increase. The polymerization time in the polymerization reaction is not particularly limited, and it is at least 0.5 hours from the last addition of the polymerization initiator, preferably at least 1 hour, more preferably at least 2 hours, and most preferably at least 5 hours. The polymerization reaction is preferably performed while refluxing the solvent in terms of ease of heat removal.

(Photoinitiator (B)) The photoinitiator (B) of the second aspect contains an intramolecular hydrogen abstraction type photoinitiator (b1). The photoinitiator (B) of the second aspect preferably further contains an intermolecular hydrogen abstraction type photoinitiator (b2). The photoinitiator (B) of the second aspect may further contain an intramolecular hydrogen abstraction type photoinitiator (b1) and an intermolecular hydrogen abstraction type photoinitiator as long as the effect of the invention is not impaired Other photoinitiators (b3) other than (b2).

[Intramolecular hydrogen abstraction type photoinitiator (b1)] The intramolecular hydrogen abstraction type photoinitiator (b1) of the second aspect has a structure capable of generating free radicals by abstracting hydrogen from the photoinitiator itself. For example, the intramolecular hydrogen abstraction type photoinitiator (b1) may have a benzoylformate structure or the like. As the intramolecular hydrogen abstraction type photoinitiator (b1) of the second aspect, for example, oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetyloxy- Ethoxy]-ethyl ester, methyl phenylglyoxylate, etc. Among them, in terms of crosslinking efficiency when fully hardened, oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl group having multiple crosslinking points in the molecule is preferred. -Acetyloxy-ethoxy]-ethyl ester. Commercially available products include "Omnirad MBF" and "Omnirad 754" manufactured by IGM RESINS B.V., for example.

[Intermolecular hydrogen abstraction type photoinitiator (b2)] The intermolecular hydrogen abstraction type photoinitiator (b2) of the second aspect has a structure capable of abstracting hydrogen from other than the photoinitiator itself to generate free radicals. The intermolecular hydrogen abstraction type photoinitiator (b2) may have, for example, a benzophenone structure or the like. As the intermolecular hydrogen abstraction type photoinitiator (b2) of the second aspect, for example, benzophenone, 4-methyl-benzophenone, 2,4,6-trimethyldiphenyl Methanone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 4-(meth)acryloxybenzophenone, 4-[2 -((meth)acryloxy)ethoxy]benzophenone, 4-(meth)acryloxy-4'-methoxybenzophenone, carboxymethoxymethoxydi Benzophenone-Polyethylene Glycol 250 Diester, Methyl 2-Benzoylbenzoate, 4-(1,3-Acryl-1,4,7,10,13-Pentaoxotridecane base) benzophenone, etc.

Among them, 4-(meth)acryloxybenzophenone and 4-[2-((( Meth)acryloxy)ethoxy]benzophenone, 4-(meth)acryloxy-4'-methoxybenzophenone, carboxymethoxymethoxybenzophenone - Polyethylene glycol 250 diester. Commercially available products include "MBP" manufactured by Shinryo Corporation, "Omnirad BP" manufactured by IGM RESINS B.V., "Omnirad 4MBZ", "Esacure TZT" and "Omnipol BP".

[Other photoinitiators (b3)] As other photoinitiators (b3) of the second aspect, for example: diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenyl Propan-1-one, benzoyl dimethyl ketal, 4-(2-hydroxyethoxy) phenyl-(2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 2 -Methyl-2-morpholinyl(4-thiomethylphenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)butanone, 2-Hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]acetone oligomers and other acetophenones; Benzoin, Benzoin Methyl Ether, Benzoin Ethyl Ether, Benzoin Isopropyl Ether, Benzoin Benzoin such as isobutyl ether; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-tri Acylphosphine oxides such as methyl-pentylphosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

、2,4-二異丙基-9-氧硫𠮿

等。  光起始劑(B)之助劑可單獨使用1種，亦可併用2種以上。As an auxiliary agent of the photoinitiator (B) of the second aspect, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michelerone), 4,4'-Diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, ethyl 4-dimethylaminobenzoate, 4-dimethylaminobenzoic acid (n-butoxy) Ethyl ester, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethyl-9-oxothiol

, 2,4-Diisopropyl-9-oxosulfur

wait. The auxiliaries of the photoinitiator (B) may be used alone or in combination of two or more.

(Crosslinking agent (C)) The adhesive composition of the second aspect preferably further contains a crosslinking agent (C) in addition to the acrylic resin (A) and the photoinitiator (B). The crosslinking agent (C) may, for example, be an active energy ray crosslinking agent (c1) or a thermal crosslinking agent (c2). The active energy ray crosslinking agent (c1) and thermal crosslinking agent (c2) can be used alone or in combination of two or more.

In the case of containing only the active energy ray crosslinking agent (c1) as the crosslinking agent (C), multistage hardening can be achieved only by controlling the amount of active energy ray. Also, when the active energy ray crosslinking agent (c1) and thermal crosslinking agent (c2) are contained as the crosslinking agent (C), multistage curing can also be achieved by using thermal curing and active energy ray curing together. By controlling the cross-linking reaction in the above way, the cohesion of the adhesive layer as a whole can be adjusted, and stable adhesive properties can be obtained after one hardening or after complete hardening.

[Active energy ray crosslinking agent (c1)] The active energy ray crosslinking agent (c1) may, for example, be a polyfunctional crosslinking agent containing two or more ethylenically unsaturated groups in one molecule. For example, hexanediol di(meth)acrylate, butanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, (Meth)acrylate, (poly)ethylene glycol mono(meth)acrylate, (poly)butylene glycol mono(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, ( Poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, (poly)pentamethylene glycol di(meth)acrylate, (poly)hexaethylene Methyl glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate ester, trimethylolpropane tri(meth)acrylate, EO modified trimethylolpropane tri(meth)acrylate, glycerol tri(meth)acrylate, EO modified glycerol tri(meth)acrylate ester, tetramethylolmethane tri(meth)acrylate, isocyanuric acid ethylene oxide modified tri(meth)acrylate, multifunctional urethane (meth)acrylate, etc. Among them, in terms of the balance of adhesive properties after hardening, (meth)acrylates containing two ethylenically unsaturated groups are preferred, and (poly)ethylene glycol di(meth)acrylate is particularly preferred. , (poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate. The polyfunctional crosslinking agent may be used alone or in combination of two or more.

[Thermal crosslinking agent (c2)] The thermal crosslinking agent (c2) can exert excellent adhesion mainly by reacting with the functional group derived from the functional group-containing monomer as the constituent monomer of the acrylic resin (A). force. Examples include: isocyanate-based crosslinking agent (c2-1), epoxy-based crosslinking agent (c2-2), aziridine-based crosslinking agent (c2-3), melamine-based crosslinking agent (c2-4 ), aldehyde crosslinking agent (c2-5), amine crosslinking agent (c2-6), metal chelate crosslinking agent (c2-7). Among them, an isocyanate-based crosslinking agent (c2-1) can be suitably used from the point of improving the adhesiveness with a base material or the reactivity with an acrylic resin (A). The thermal crosslinking agent (c2) can be used alone or in combination of two or more.

Examples of the isocyanate-based crosslinking agent (c2-1) include toluene diisocyanate-based compounds such as 2,4-toluene diisocyanate and 2,6-toluene diisocyanate; 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, tetramethylxylylene diisocyanate and other xylylene diisocyanate compounds; 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate and other aromatic isocyanate compounds ; Hexamethylene diisocyanate, trimethylhexamethylene diisocyanate and other hexamethylene diisocyanate compounds, lysine diisocyanate and other aliphatic isocyanate compounds; isophorone diisocyanate and other alicyclic isocyanate compounds compounds; adducts of these isocyanate compounds and polyol compounds such as trimethylolpropane; biuret or isocyanurate forms of these isocyanate compounds, etc.

Among the isocyanate-based crosslinking agents (c2-1), it is preferable to use an aromatic isocyanate-based compound, particularly preferably a toluene diisocyanate-based compound, since it is excellent in reactivity. Moreover, it is preferable to use an aliphatic isocyanate type compound from the viewpoint of yellowing suppression, and a hexamethylene diisocyanate type compound is especially preferable.

As the epoxy-based crosslinking agent (c2-2), for example, bisphenol A-epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol di Glycidyl ether, glycerol triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether Glyceryl erythritol, diglycerol polyglycidyl ether, etc.

Examples of the aziridine-based crosslinking agent (c2-3) include: tetramethylolmethane-tri-β-aziridinyl propionate, trimethylolpropane-tri-β-aziridine propionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxyamide), N,N'-hexamethylene-1,6-bis(1- Aziridine carboxamide), etc.

As the melamine-based crosslinking agent (c2-4), for example, hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentylmelamine, Oxymethylmelamine, hexahexyloxymethylmelamine, melamine resin, etc.

As an aldehyde crosslinking agent (c2-5), glyoxal, malondialdehyde, succinaldehyde, maleic dialdehyde, glutaraldehyde, formaldehyde, acetaldehyde, benzaldehyde, etc. are mentioned, for example.

Examples of the amine-based crosslinking agent (c2-6) include hexamethylenediamine, triethylenediamine, polyethyleneimine, hexamethylenetetramine, and diethylenetriamine. , triethylenetetramine, isophorone diamine, amino resin, polyamide, etc.

Examples of the metal chelate crosslinking agent (c2-7) include acetylene of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. Acetone or acetyl acetyl ester coordination compounds, etc.

(Silane coupling agent (D)) The adhesive composition of the second aspect preferably further contains a silane coupling agent (D) as an acrylic resin (A), a photoinitiator ( Compounds other than B) and the crosslinking agent (C).

The silane coupling agent (D) is an organosilicon compound containing one or more reactive functional groups and an alkoxy group bonded to a silicon atom in its structure. Monomer type and oligomer type are mentioned as a silane coupling agent (D).

As a reactive functional group in a silane coupling agent (D), an epoxy group, (meth)acryl group, a mercapto group, a hydroxyl group, a carboxyl group, an amine group, an amide group, an isocyanate group etc. are mentioned, for example. Among them, epoxy group and mercapto group are preferable in terms of durability and secondary processability.

The content ratio of the reactive functional group in the silane coupling agent (D) is preferably 3,000 g/mol or less, more preferably 1,500 g/mol or less, further preferably 1,000 g/mol or less. When the reactive functional group is within the above numerical range, the balance between durability and secondary workability improves. The lower limit of the content ratio of the reactive functional group in the silane coupling agent (D) is 200 g/mol.

The alkoxy group bonded to the silicon atom in the silane coupling agent (D) is preferably an alkoxy group having 1 to 8 carbon atoms in terms of durability and storage stability. Among them, methoxy and ethoxy are more preferable. The silane coupling agent (D) may also have a reactive functional group and an organic functional group other than an alkoxy group bonded to a silicon atom, such as an alkyl group or a phenyl group.

As the silane coupling agent (D), for example, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, γ-shrink Glyceryloxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyl Dimethoxysilane, Methyltri(glycidyl)silane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethylsilane Oxysilane etc. Among these, γ-glycidoxypropyltrimethoxysilane is preferable in terms of heat resistance. Silane coupling agent (D) can be used alone or in combination of two or more.

(Carbodiimide Compound (E)) The adhesive composition of the second aspect preferably further contains a carbodiimide compound (E) as the acrylic resin (A) in terms of heat resistance. ), photoinitiator (B), crosslinking agent (C) and silane coupling agent (D). As the carbodiimide-based compound (E), for example, bis(2,6-diisopropylphenyl)carbodiimide, dicyclohexylcarbodiimide, diisopropylcarbodiimide, Diimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, tert-butylisopropylcarbodiimide, diphenylcarbon Monocarbodiimides such as diimide, di-tert-butylcarbodiimide, bis(dodecyl)carbodiimide, etc.; polycarbodiamides with plural carbodiimides present imine or cyclic carbodiimide, etc. Among them, in terms of heat resistance, monocarbodiimide-based compounds are preferred, and bis(2,6-diisopropylphenyl)carbodiimide is more preferred. The carbodiimide compound (E) may be used alone or in combination of two or more.

(Optional Component) The adhesive composition of the second aspect may contain an adhesive as another optional component as needed. The adhesive composition of the second aspect may contain previously known additives such as crosslinking accelerators, antistatic agents, adhesion imparting agents, and functional pigments.

(Composition of Adhesive Composition) In the second aspect, the content of the acrylic resin (A) is preferably at least 80% by weight, more preferably 90 to 99.9% by weight, and still more preferably Preferably, it is 92 to 99.9% by weight. If the content of the acrylic resin (A) is within the above numerical range, it is easy to obtain excellent adhesive properties in a low crosslinked state after primary curing.

In the second aspect, the content of the photoinitiator (B) is preferably 0.1-5.0 parts by weight, more preferably 0.5-4.0 parts by weight, and even more preferably 100 parts by weight of the acrylic resin (A). 1.0 to 3.0 parts by weight. If the content of the photoinitiator (B) is within the above numerical range, sufficient curability can be obtained when fully cured.

In the second aspect, the content of the intramolecular hydrogen abstraction photoinitiator (b1) is preferably 0.1-5.0 parts by weight, more preferably 0.5-3.0 parts by weight relative to 100 parts by weight of the acrylic resin (A) . If the content of the hydrogen-abstracting photoinitiator (b1) in the molecule is too much, it tends to change color after prolonged exposure to heat and humidity. If the content of the intramolecular hydrogen-abstracting photoinitiator (b1) is too small, the degree of crosslinking will not increase, resulting in poor adhesive properties during primary curing or durability after complete curing.

In the second aspect, when the photoinitiator (B) contains an intermolecular hydrogen abstraction type photoinitiator (b2), the content of the intermolecular hydrogen abstraction type photoinitiator (b2) is 100 parts by weight of the resin (A), preferably 0.1-3.0 parts by weight, more preferably 0.5-2.0 parts by weight. If the content of intermolecular hydrogen abstraction type photoinitiator (b2) is too much, there is a tendency to bleed out and cause poor durability. If the content of the intermolecular hydrogen-abstracting photoinitiator (b2) is too small, the degree of crosslinking will not increase, resulting in poor adhesive properties during primary curing or durability after complete curing.

In the second aspect, when the photoinitiator (B) contains other photoinitiator (b3), the content of the photoinitiator (b3) is 100 parts by weight relative to the acrylic resin (A). It is preferably at most 2.0 parts by weight, more preferably at most 1.0 parts by weight.

In the second aspect, when the adhesive composition contains a crosslinking agent (C), the content of the crosslinking agent (C) is usually preferably 20 parts by weight relative to 100 parts by weight of the acrylic resin (A) Below, it is more preferable that it is 0.001-10 weight part, and it is still more preferable that it is 0.1-7.5 weight part. If the content of the crosslinking agent (C) is too high, the adhesive force tends to decrease. When the content of the crosslinking agent (C) is too small, durability tends to decrease.

In the second aspect, when the adhesive composition contains the active energy ray crosslinking agent (c1), the content of the active energy ray crosslinking agent (c1) is usually 100 parts by weight relative to the acrylic resin (A). Preferably it is 0.01-20 weight part, More preferably, it is 0.1-10 weight part, More preferably, it is 0.5-7.5 weight part. If the content of the active energy ray crosslinking agent (c1) is too small, sufficient durability may not be obtained due to insufficient cohesive force. When the content of the active energy ray crosslinking agent (c1) is too large, the adhesive property at the time of primary curing tends to decrease.

In the second aspect, when the adhesive composition contains a thermal crosslinking agent (c2), the content of the thermal crosslinking agent (c2) is usually 0.001 parts by weight relative to 100 parts by weight of the acrylic resin (A). -5 parts by weight, more preferably 0.02-1 part by weight, still more preferably 0.05-0.5 parts by weight. If the content of the thermal crosslinking agent (c2) is too small, the cohesive force will be insufficient and the adhesive properties will tend to decrease during primary hardening. If the content of the thermal crosslinking agent (c2) is too high, the adhesive force tends to decrease when fully hardened.

In the second aspect, an active energy ray crosslinking agent (c1) and a thermal crosslinking agent (c2) may be used together as the crosslinking agent (C). When used in combination, the content ratio (c1/c2) of the active energy ray crosslinking agent (c1) to the thermal crosslinking agent (c2) is preferably 100/1 to 100/50 by weight ratio.

In the second aspect, when the adhesive composition contains the silane coupling agent (D), the content of the silane coupling agent (D) is preferably 0.001 to 3 parts by weight relative to 100 parts by weight of the acrylic resin (A) part, more preferably 0.005 to 1 part by weight, still more preferably 0.01 to 0.5 part by weight, especially preferably 0.015 to 0.3 part by weight. If the content of the silane coupling agent (D) is too small, it tends to be difficult to obtain the effect of improving durability. If the content of the silane coupling agent (D) is too high, the adhesive force tends to decrease due to effects such as bleeding.

In the second aspect, when the adhesive composition contains the carbodiimide compound (E), the content of the carbodiimide compound (E) is 100 parts by weight of the acrylic resin (A) , preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, further preferably 0.2 to 2 parts by weight, especially preferably 0.3 to 1 part by weight. If the content of the carbodiimide compound (E) is too small, the thermal stability of the acrylic resin (A) tends to decrease. When the content of the carbodiimide-based compound (E) is too high, durability tends to decrease due to effects such as bleeding.

In the second aspect, when other adhesives or additives are added to the adhesive combination, the content of the other adhesives or additives is preferably 10 parts by weight or less with respect to 100 parts by weight of the acrylic resin (A), More preferably, it is 5 parts by weight or less.

(Preparation of Adhesive Composition) By mixing acrylic resin (A), photoinitiator (B), optional crosslinking agent (C), silane coupling agent (D), carbodiimide compound (E) Other optional ingredients are mixed to obtain the adhesive composition of the second aspect. The mixing method is not particularly limited, and the following various methods can be used: a method of mixing the ingredients at one time; a method of mixing the remaining ingredients one at a time or sequentially after mixing any of the ingredients.

(Applications) The adhesive composition of the second aspect can be suitably used as an adhesive for a multistage curable adhesive sheet that is hardened in a plurality of stages. According to the adhesive composition of the second aspect, excellent adhesive properties can also be obtained in a low-crosslinked state after primary curing. Furthermore, after it is completely cured, it not only exhibits adhesive properties such as usual adhesive force, but also exhibits excellent durability when laminating members of various types and shapes such as polarizing plates and glass.

The adhesive composition of the second aspect has excellent adhesive properties such as low tackiness in a low-crosslinked state after primary curing, high constant load retention, etc., thereby improving workability and reliability. Therefore, it can be suitably used especially for the use of the adhesive agent used for a touch panel, an image display apparatus, etc., or an adhesive sheet.

<Adhesive> The adhesive of the second aspect is obtained by cross-linking the adhesive composition of the second aspect above. By crosslinking (curing) the adhesive composition of the second aspect, the acrylic resin (A) contained in the adhesive composition forms a crosslinked structure in at least one of intramolecular and intermolecular. As a result, the adhesive composition of the second aspect is crosslinked to become the adhesive of the second aspect. In the case where the acrylic resin (A) has an active energy ray crosslinkable structural site, a crosslinked structure can be formed by irradiation with active energy rays.

The adhesive of the second aspect exhibits multi-stage hardening that can be hardened in multiple stages. The adhesive of the second aspect is in a low cross-linking state by primary curing before complete curing. Complete hardening and primary hardening may not be clearly distinguished, for example, they can be distinguished based on the difference in gel fraction or dynamic viscoelasticity.

In any one of the primary hardening step and the complete hardening step, the hardening method is not particularly limited, and any one of heating or active energy ray irradiation may be used. In addition, one hardening step may be performed in plural times, or multi-step hardening may be performed in order to make it into a fully hardened state. The adhesive of the second aspect has excellent adhesive properties after primary curing, so it can be suitably used for lamination of optical components constituting touch panels or image display devices.

The adhesive of the second aspect can be considered to contain at least a cross-linked product of the acrylic resin (A) of the second aspect. The cross-linked product may be a partially cross-linked product in which at least a part of the acrylic resin (A) is partially cross-linked, or may be a fully cross-linked product in which all of the acrylic resin (A) is fully cross-linked. Moreover, the adhesive agent of a 2nd aspect may contain both the partially crosslinked thing and the fully crosslinked thing of an acrylic resin (A).

<Adhesive Sheet> The adhesive sheet of the second aspect has an adhesive layer containing the adhesive of the second aspect. The adhesive sheet of the second aspect can exhibit multi-stage hardening in which the adhesive layer hardens in multiple stages.

An adhesive sheet can be produced by providing an adhesive layer containing the adhesive of the second aspect on a base sheet. Moreover, a double-sided adhesive sheet can be produced by providing an adhesive layer on a release sheet. Furthermore, an adhesive layer is formed on the release sheet instead of the substrate sheet, and the release sheet is attached to the adhesive layer on the opposite side, thereby also making a double-sided adhesive sheet without a substrate. It is also possible to further form an adhesive layer on the formed adhesive layer, and further form a thick-film adhesive layer. When the obtained adhesive sheet or double-sided adhesive sheet is used, the release sheet is peeled off from the adhesive layer for use.

As a method of producing the adhesive sheet of the second aspect, methods such as the following (i) and (ii) may be mentioned, for example. (i) A method of producing an adhesive sheet after applying a coating liquid obtained by dissolving the adhesive composition of the second aspect in a solvent. (ii) A method of producing an adhesive sheet after melting the adhesive composition of the second aspect by heating.

The method of (i) will be described. When preparing an adhesive sheet after applying a coating liquid obtained by dissolving the adhesive composition of the second aspect in a solvent, the amount of the adhesive composition containing the second aspect is adjusted with an appropriate organic solvent. The concentration of the coating solution is directly applied to the substrate sheet. Thereafter, it is dried by, for example, heat treatment at 80 to 105° C. for 0.5 to 10 minutes, and attached to a base material sheet or a release sheet. Thereafter, the adhesive composition is crosslinked (hardened) by active energy ray irradiation or aging to produce an adhesive sheet having an adhesive layer containing the adhesive.

As an organic solvent used for concentration adjustment, what was mentioned as the organic solvent used for the polymerization reaction of an acrylic resin (A) is mentioned. The concentration of the adhesive composition is usually 20 to 60% by weight, preferably 30 to 50% by weight, based on solid content.

The method of (ii) will be described. When the adhesive composition of the second aspect is melted by heating to form an adhesive sheet, by applying it to one or both sides of the base sheet in a melted state, and then cooling method or a method of extruding onto a base sheet through a T-die or the like for lamination, the adhesive layer is formed on one side or both sides of the base sheet so as to have a desired thickness. Then, if necessary, attach a release sheet to the adhesive layer, thereby producing an adhesive sheet.

In addition, after forming the adhesive layer on the base sheet, if necessary, it is subjected to active energy ray irradiation treatment, and aging is performed, whereby an adhesive sheet having an adhesive layer formed by hardening (crosslinking) the adhesive composition can be produced. material. Furthermore, the adhesive layer is formed on the release sheet, and the release sheet is attached to the adhesive layer on the opposite side, so that a double-sided adhesive sheet without a substrate can also be produced. When the obtained adhesive sheet or double-sided adhesive sheet is used, the release sheet is peeled off from the adhesive layer for use.

As the base sheet, for example, polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate/isophthalic acid Polyester resins such as ethylene glycol copolymer; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyvinyl fluoride, polyvinylidene fluoride, polyfluoroethylene, etc. Polyfluoroethylene resin; nylon 6, nylon 6,6 and other polyamides; polyvinyl chloride, polyvinyl chloride/vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyethylene Vinyl polymers such as alcohol and vinylon; Cellulose resins such as cellulose triacetate and celluloid; Acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate Resin; polystyrene; polycarbonate; polyarylate; polyimide and other synthetic resin sheets; aluminum, copper, iron and other metal foils; high-grade paper, cellophane and other paper; including glass fiber, natural fiber, synthetic fiber, etc. woven or non-woven fabrics. These base sheets may be used as a single layer body or as a multilayer body in which two or more types are laminated. Among them, a synthetic resin sheet is preferable in terms of weight reduction and the like.

As the release sheet, for example, those obtained by subjecting various synthetic resin sheets, paper, woven fabrics, non-woven fabrics, etc. to the base sheet to a release treatment can be used. As the release sheet, for example, a silicon-based release sheet is preferably used.

The application method of the adhesive composition is not particularly limited. For example, methods such as roll coating, die coating, gravure coating, chipped wheel coating, slit coating, and screen printing may be mentioned.

As active energy rays, rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, and infrared rays; electromagnetic waves such as X-rays and γ-rays; electron beams; proton beams; neutron rays, etc., can be used. Curing using ultraviolet rays is preferred in terms of curing speed, availability of irradiation equipment, price, and the like.

Regarding the gel fraction before the adhesive layer of the adhesive sheet is completely hardened, regardless of the shape of the adherend, it is easy to stick and the adhesive layer can hold the adherend after sticking. , preferably 0.1 to 60% by weight, more preferably 1 to 50% by weight, especially preferably 5 to 45% by weight.

With regard to the gel fraction after the adhesive layer of the adhesive sheet is completely hardened, it is preferably 50 to 95% by weight, more preferably 55 to 90% by weight, and especially preferably 60 to 85% by weight. When the gel fraction is too low, durability tends to decrease due to decreased cohesive force. If the gel fraction is too high, there is a tendency for the adhesive force to decrease due to the increase in the cohesive force.

The gel fraction can be appropriately adjusted by the following method, for example.・Adjust the dose of active energy rays.・Adjust the content of the active energy ray cross-linking structure in the acrylic resin (A).・Adjust the type or amount of photoinitiator (B) and crosslinking agent (C).

The gel fraction serves as a standard for the degree of crosslinking (degree of hardening), and can be calculated, for example, by the following method. That is, an adhesive sheet formed by wrapping a polymer sheet (such as a polyethylene terephthalate (PET) film, etc.) as a base material with a 200 mesh SUS wire mesh to form an adhesive layer (not shown For those with a release sheet), dip in toluene maintained at 23°C for 24 hours, and use the weight percentage of the insoluble adhesive components remaining in the wire mesh as the gel fraction. However, it is calculated by subtracting the weight of the substrate from the weight before and after dissolving toluene.

The thickness of the adhesive layer of the adhesive sheet is usually preferably from 50 to 3000 μm, more preferably from 75 to 1000 μm, and especially preferably from 100 to 350 μm. When the thickness of the adhesive layer is too thin, the impact absorption tends to decrease. When the thickness of the adhesive layer is too thick, for example, when sticking to an optical member, the overall thickness increases and the practicability tends to decrease.

The thickness of the adhesive layer is obtained by subtracting the measured value of the thickness of the constituent members other than the adhesive layer from the measured value of the thickness of the entire laminate including the adhesive layer using "ID-C112B" manufactured by Mitutoyo Co., Ltd. value.

The adhesive layer of the adhesive sheet according to the second aspect preferably has a haze value of 2% or less when the thickness of the adhesive layer is 100 μm, more preferably 0-1.5%, especially preferably 0-1% . When the haze value is too high, the pressure-sensitive adhesive layer tends to become white and reduce transparency. The haze value is measured by using HAZE MATER NDH4000 (manufactured by Nippon Denshoku Industries Co., Ltd.) to measure the diffuse transmittance and total light transmittance, and substitute the obtained values of diffuse transmittance (DT) and total light transmittance (TT) into the following [Formula 1] and calculated. This machine conforms to JIS K7361-1. Haze value (%)＝(DT/TT)×100・・・[Formula 1]

In the second aspect, an optical member with an adhesive layer attached can be obtained by forming an adhesive laminated layer on the optical member. For example, after adhering the adhesive layer of the adhesive sheet of the second aspect with the adhesive layer formed on the release sheet to the optical member, the release sheet is peeled off, thereby obtaining an optical device with an adhesive layer. member. Moreover, optical members can also be bonded together using the said double-sided adhesive sheet.

The optical member may, for example, be a member constituting a touch panel or an image display device. For example, a display (organic EL, liquid crystal), a transparent conductive film substrate (ITO substrate), a protective film (glass), a transparent antenna (film), a transparent wiring, etc. are mentioned.

Preferred implementations of the second aspect described above include the following [B1] to [B8], but are not limited thereto. [B1] An adhesive composition comprising an acrylic resin (A) and a photoinitiator (B), wherein the acrylic resin (A) is a polymerization product of the following copolymerization component (a), the acrylic resin The glass transition temperature of (A) based on dynamic viscoelasticity is above -10°C, and the photoinitiator (B) contains an intramolecular hydrogen abstraction type photoinitiator (b1). The above-mentioned copolymerization component (a) contains at least an alkyl (meth)acrylate (a1) having an alkyl group having 12 or less carbon atoms and having a homopolymer glass transition temperature of -20 to 120°C and an alkyl chain, a hydroxyl group and ethylenically unsaturated hydroxyalkyl monomer (a2), the content of the above-mentioned alkyl (meth)acrylate (a1) is 30% by weight or more relative to 100% by weight of the above-mentioned copolymerization component (a), and the above-mentioned hydroxyalkyl The content of the base monomer (a2) is 0.1% by weight or more relative to 100% by weight of the above-mentioned copolymerization component (a), and the average carbon number of the alkyl chain of the above-mentioned hydroxyalkyl monomer (a2) in the copolymerization component (a) is 2.1 or above. [B2] The adhesive composition as described in [B1], wherein the photoinitiator (B) further contains an intermolecular hydrogen abstraction type photoinitiator (b2). [B3] The adhesive composition as described in [B1] or [B2], which further contains a crosslinking agent (C). [B4] The adhesive composition described in any one of [B1] to [B3], wherein the acrylic resin (A) has a weight average molecular weight of 50,000 to 500,000. [B5] An adhesive obtained by crosslinking the adhesive composition described in any one of [B1] to [B4]. [B6] The adhesive described in [B5], wherein the crosslinking is performed by irradiation of active energy rays. [B7] An adhesive sheet having an adhesive layer comprising the adhesive described in [B5] or [B6]. [B8] The adhesive sheet as described in [B7], wherein the above-mentioned adhesive layer is multistage hardening that is hardened in a plurality of stages.

[Third form] Hereinafter, although the embodiment of the third aspect of the present invention will be described in detail, they are disclosed as representative examples of preferred implementation aspects.

<Adhesive composition> The adhesive composition of the third aspect contains an acrylic resin (A) and a photoinitiator (B). The adhesive composition of the third aspect may further contain a crosslinking agent (C), a silane coupling agent (D), and a carbodiimide in addition to the acrylic resin (A) and the photoinitiator (B). It is a compound (E) and other optional components. Hereinafter, each component is demonstrated sequentially.

(Acrylic resin (A)) The copolymerization component containing branched chain alkyl (meth)acrylate (a1) with a glass transition temperature of the acrylic resin (A) homopolymer of the third aspect being -30°C or higher (a) Polymerization product. The copolymerization component (a) is a general term for monomer components having a polymerizable double bond. The copolymerization component (a) does not contain a polymerization initiator or a polymerization solvent.

The copolymerization component (a) of the third aspect contains, in addition to branched alkyl (meth)acrylate (a1), may further contain (meth)acrylate (a2) containing hydroxyl group, active energy ray At least one or more of the group consisting of the (meth)acrylate monomer (a3) and the ethylenically unsaturated monomer (a4) of the crosslinkable structural site.

[Branched alkyl (meth)acrylate (a1)] The branched alkyl (meth)acrylate (a1) of the third aspect is a (meth)acrylate having an alkyl group containing a branch. The number of carbon atoms in the branched alkyl group of the (meth)acrylate branched alkyl ester (a1) is not particularly limited. For example, it is preferably 30 or less, more preferably 20 or less, and still more preferably 3-10. Generally, the lower limit of the number of carbons required to form a branch is 3.

The branched alkyl (meth)acrylate (a1) of the third aspect is a monomer whose homopolymer glass transition temperature (hereinafter referred to as "Tg") is -30°C or higher. The Tg of the homopolymer of the branched alkyl (meth)acrylate (a1) of the third aspect is preferably -30 to 150°C, more preferably -20°C to 140°C, and more preferably -15 to 130°C, preferably -10 to 100°C. Since the Tg of the homopolymer of the branched alkyl (meth)acrylate (a1) is within the above numerical range, excellent adhesion can also be obtained when it is attached to an adherend with a complex shape to which strong stress is applied. Adhesive sheet.

The homopolymer of the branched alkyl (meth)acrylate (a1) of the third aspect is a homopolymer of the branched alkyl (meth)acrylate (a1). As the Tg of the homopolymer of the branched alkyl (meth)acrylate (a1), the analysis value of the standard described in "POLYMER HANDBOOK" published by Wiley etc. can be used.

As the branched alkyl (meth)acrylate (a1) of the third aspect, for example, 2-ethylhexyl methacrylate (Tg: -10°C), isobutyl methacrylate (Tg : 48°C), tert-butyl methacrylate (Tg: 107°C), etc. Among them, 2-ethylhexyl methacrylate and isobutyl methacrylate are preferable in terms of adhesive properties. The branched alkyl (meth)acrylate (a1) may be used alone or in combination of two or more.

[Hydroxyl-containing (meth)acrylate (a2)] The third aspect of the hydroxyl-containing (meth)acrylate (a2) is a (meth)acrylate with a hydroxyl group (among them, (meth)acrylate except alkanyl esters (a1)). When the polymerization component constituting the acrylic resin (A) contains a hydroxyl group-containing (meth)acrylate (a2), a structural site derived from a polar group-containing monomer is introduced into the acrylic resin (A).

As the hydroxyl group-containing (meth)acrylate (a2) of the third aspect, for example, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, (meth)acrylate 5-hydroxypentyl acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate and other hydroxyalkyl acrylates; caprolactone-modified 2-hydroxyethyl (meth)acrylate Modified monomers such as caprolactone; Oxyalkylene modified monomers such as diethylene glycol (meth)acrylate and polyethylene glycol (meth)acrylate; 2-Acryloxyethyl-2 -Hydroxyethyl phthalic acid, N-hydroxymethyl (meth)acrylamide, hydroxyethyl acrylamide and other (meth)acrylates containing primary hydroxyl groups; 2-hydroxypropyl (meth)acrylate , 2-hydroxybutyl (meth)acrylate, 3-chloro 2-hydroxypropyl (meth)acrylate and other (meth)acrylates containing secondary hydroxyl groups; 2,2-dimethyl (meth)acrylate Hydroxyl-containing (meth)acrylates such as 2-hydroxyethyl ester. Among them, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferable. Hydroxyl-containing (meth)acrylates (a2) may be used alone or in combination of two or more.

The hydroxyl group-containing (meth)acrylate (a2) as the third aspect is preferably the content ratio of di(meth)acrylate that may be contained as an impurity in the hydroxyl group-containing (meth)acrylate (a2) less. Specifically, the content ratio of the di(meth)acrylate that can be contained in the hydroxyl group-containing (meth)acrylate (a2) is preferably 0.5% by weight or less, more preferably 0.2% by weight or less, especially preferably It is 0.1 weight% or less, More preferably, it is 0 weight%.

The hydroxyl-containing (meth)acrylate (a2) of the third aspect also contains acrylic acid as an impurity in many cases, and its content in the hydroxyl-containing (meth)acrylate (a2) is usually 0.001 to 0.5% by weight About, it is better to use less.

[(Meth)acrylate monomer (a3) containing an active energy ray crosslinkable structural site] The acrylic resin (A) of the third aspect may also have an active energy ray crosslinkable structural site. The active energy ray crosslinkable structural site is a structural site that can form a crosslinked structure by reacting with a part of the acrylic resin (A) or other curing components that may be contained in the adhesive composition by active energy ray irradiation. In the third aspect, the active energy ray cross-linking structural site is preferably a benzophenone-based cross-linking structural site in terms of high reactivity and excellent cohesion improvement. Therefore, the copolymerization component (a) of the third aspect preferably further includes a (meth)acrylate monomer (a3) having an active energy ray crosslinking structural site (wherein, the (meth)acrylate branched chain alkyl ester (a1) and hydroxyl-containing (meth)acrylate (a2) are excluded).

The (meth)acrylate monomer (a3) having an active energy ray cross-linking structural site as the third aspect can form an efficient cross-linking structure by active energy rays such as ultraviolet rays and electron beams. In other words, a (meth)acrylate monomer having a benzophenone-based crosslinkable structural site is preferable. For example, 4-(meth)acryloxybenzophenone etc. are mentioned. The (meth)acrylate monomer (a3) containing an active energy ray crosslinking structural site may be used alone or in combination of two or more.

Also, when introducing an active energy ray crosslinkable structural site into the acrylic resin (A), in addition to copolymerizing the (meth)acrylate monomer (a3) containing the active energy ray crosslinkable structural site, the acrylic acid The resin (A) contains a hydroxyl group in advance and reacts the hydroxyl group with an ethylenically unsaturated group-containing isocyanate compound to introduce an ethylenically unsaturated group as an active energy ray crosslinkable structural site.

[Ethylenic unsaturated monomer (a4)] The copolymerization component (a) of the third aspect may further contain (meth)acrylic branched alkyl ester (a1), hydroxyl-containing (meth)acrylate (a2) ) and other copolymerizable ethylenically unsaturated monomers (a4) other than (meth)acrylate monomers (a3).

Other copolymerizable ethylenically unsaturated monomers (a4) of the third aspect include, for example, methyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl acrylate, etc. Alkyl (meth)acrylate (excluding branched alkyl (meth)acrylate (a1), hydroxyl-containing (meth)acrylate (a2) and (meth)acrylate monomer (a3) ); Phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenyldiethylene glycol (meth)acrylate, phenoxy polyethylene glycol ( Meth)acrylate, phenoxy polyethylene glycol-polypropylene glycol-(meth)acrylate, o-phenylphenoxyethyl (meth)acrylate, nonylphenol ethylene oxide adduct (meth) Aromatic ring-containing monomers such as acrylate esters; Cyclohexyloxyalkyl (meth)acrylate, tert-butylcyclohexyloxyethyl (meth)acrylate, iso-(meth)acrylate, Alicyclic monomers such as dicyclopentanyl (meth)acrylate; 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methyl (meth)acrylate Oxybutyl ester, 2-butoxyethyl (meth)acrylate, 2-butoxydiethylene glycol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxy Triethylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, methoxydipropylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate Esters, Octyloxypolyethylene glycol-polypropylene glycol mono(meth)acrylate, Lauryloxypolyethylene glycol mono(meth)acrylate, Stearyloxypolyethylene glycol mono(meth)acrylate Monomers containing ether chains such as acrylates; (meth)acrylic acid, β-carboxyethyl acrylate and other acrylic acid dimers, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, pentene di Acid, itaconic acid, N-glycolic acid, cinnamic acid and other carboxyl-containing monomers; (meth)acrylamide, N-(n-butoxyalkyl)(meth)acrylamide, N,N-di Amino-containing monomers such as methyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dimethylaminoalkyl(meth)acrylamide; Acrylonitrile, Methacrylonitrile, Styrene, α-Methylstyrene, Vinyl Acetate, Vinyl Propionate, Vinyl Stearate, Vinyl Chloride, Vinylidene Chloride, Alkyl Vinyl Ether, Vinyl Toluene , Vinylpyridine, Vinylpyrrolidone, Dialkyl Itonate, Dialkyl Fumarate, Allyl Alcohol, Acryloyl Chloride, Methyl Vinyl Ketone, N-Acrylamide Methyl Trimethyl ammonium chloride, allyl trimethyl ammonium chloride, dimethyl allyl vinyl ketone, etc. Other ethylenically unsaturated monomers (a4) may be used alone or in combination of two or more.

For the purpose of increasing the molecular weight of the acrylic resin (A), it is also possible to use in combination: ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, Compounds having two or more ethylenically unsaturated groups, such as (meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, and divinylbenzene.

[Composition of the copolymerization component (a) of the third aspect] In the third aspect, the content of the branched chain alkyl (meth)acrylate (a1) is preferably 100% by weight of the copolymerization component (a). 10% by weight or more, more preferably 10 to 60% by weight, further preferably 15 to 50% by weight, particularly preferably 20 to 45% by weight. If the content of the branched alkyl (meth)acrylate (a1) is too small, the adhesive property at the time of primary curing tends to decrease. When the content of the branched alkyl (meth)acrylate (a1) is too large, the adhesive properties after complete curing tend to decrease.

In the third aspect, the content of the hydroxyl group-containing (meth)acrylate (a2) is preferably at least 5% by weight, more preferably 10 to 40% by weight, relative to 100% by weight of the copolymerization component (a), and further Preferably it is 12 to 30% by weight. When there is too little content of the hydroxyl group containing (meth)acrylate (a2), it exists in the tendency for heat-and-moisture resistance to fall. When the content of the hydroxyl group-containing (meth)acrylate (a2) is too large, the self-crosslinking reaction of the acrylic resin tends to easily occur and the heat resistance tends to decrease.

In the third aspect, the content of the (meth)acrylate monomer (a3) is preferably 0.01 to 5% by weight, more preferably 0.1 to 2% by weight relative to 100% by weight of the copolymerization component (a), and further Preferably it is 0.2 to 1% by weight. If the content of the (meth)acrylate monomer (a3) is too small, the retention force at the time of forming a crosslinked structure by active energy rays tends to decrease. Also, when forming a cross-linked structure in order to produce a processable adhesive sheet, a large amount of active energy rays is required. As a result, a large amount of energy is required to produce an adhesive sheet, and efficient production tends to be difficult. If the content of (meth)acrylate monomer (a3) is too high, the cohesive force of the system as a whole will be excessively increased and the adhesive force will tend to decrease.

In the third aspect, the content of other ethylenically unsaturated monomers (a4) is usually preferably 80% by weight or less, more preferably 70% by weight or less, and even more preferably 60% by weight or less. If the content of other ethylenically unsaturated monomers (a4) is too high, the adhesive properties at low crosslinking may decrease.

The acrylic resin (A) of the third aspect can be regarded as a polymer having a structural unit based on an alkyl (meth)acrylate (a1). Also, in this case, the acrylic resin (A) may further have a unit selected from hydroxyl-containing (meth)acrylates if necessary, in addition to the structural unit based on the (meth)acrylic branched alkyl ester (a1). At least one or more of the group consisting of a structural unit derived from (a2), a structural unit derived from a (meth)acrylate monomer (a3), and a structural unit derived from an ethylenically unsaturated monomer (a4). In this case, the ratio of the structural units based on each monomer can be determined according to the composition of the copolymerization component (a), and the same applies to the preferable aspect.

The acrylic resin (A) of the third aspect has a glass transition temperature based on dynamic viscoelasticity of -10°C or higher, preferably -5 to 20°C, more preferably 0 to 15°C, and more preferably 2 to 13°C ℃. When the glass transition temperature based on dynamic viscoelasticity is too high, the adhesive force tends to decrease due to a decrease in step followability or a decrease in adhesion of the adhesive layer. If the glass transition temperature based on dynamic viscoelasticity is too low, the adhesive properties at the time of low crosslinking tend to decrease.

The glass transition temperature based on dynamic viscoelasticity can be obtained by the following measuring method. An acrylic resin solution containing only acrylic resin (A) and an organic solvent is prepared by using an appropriate organic solvent. After adjusting the concentration of the acrylic resin solution, apply it on the release sheet so that the thickness after drying becomes 50 μm. Afterwards, it is dried by heat treatment at 90-105°C for 5-10 minutes to remove the organic solvent, and then attach it to a release sheet to produce an acrylic resin sheet containing more than 99% of acrylic resin material. Thereafter, a plurality of acrylic resin sheets were laminated to produce an acrylic resin sheet having a thickness of about 800 μm. The dynamic viscoelasticity of the prepared sheet was measured under the following conditions, and the temperature at which the loss tangent (loss elastic modulus G''/storage elastic modulus G'=tanδ) reached the maximum was read as the value based on dynamic viscoelasticity Glass transition temperature of acrylic resin (A).

(Measurement conditions of dynamic viscoelasticity) Measuring machine: Dynamic viscoelasticity measuring device (trade name: DVA-225, manufactured by Japan IT Measurement Control Co., Ltd.) Deformation mode: shear Strain: 0.1% Measuring temperature: -100～60°C Measuring frequency : 1Hz

In the third aspect, the weight average molecular weight of the acrylic resin (A) is 400,000 or less, preferably 10,000-350,000, more preferably 50,000-300,000, still more preferably 100,000-290,000, especially preferably 150,000-280,000. When the weight average molecular weight of an acrylic resin (A) is too large, it exists in the tendency for a viscosity to become too high and applicability or handleability to fall. When the weight-average molecular weight of the acrylic resin (A) is too small, the cohesive force tends to decrease and the adhesive property tends to decrease. The weight average molecular weight of the acrylic resin (A) is the weight average molecular weight at the end of the production, which is the weight average molecular weight of the acrylic resin (A) that has not been heated after production.

The weight average molecular weight of the acrylic resin (A) is the weight average molecular weight converted from the standard polystyrene molecular weight. By using three columns in series in a high-performance liquid chromatography (manufactured by Waters Corporation of Japan, "Waters 2695 (body)" and "Waters 2414 (detector)"): Shodex GPC KF-806L (exclusion limit molecular weight: 2×10 ⁷ , separation range: 100 to 2×10 ⁷ , number of theoretical plates: 10,000 plates/root, filler material: styrene-divinylbenzene copolymer, filler particle size: 10 μm). The number average molecular weight can also be measured by the same method. In addition, the degree of dispersion can be obtained from the weight average molecular weight and the number average molecular weight.

The degree of dispersion (weight average molecular weight/number average molecular weight) of the acrylic resin (A) is preferably 15 or less, more preferably 10 or less, further preferably 7 or less, particularly preferably 5 or less. When the dispersion of the acrylic resin (A) is too high, the durability of the adhesive layer tends to decrease. Also, there is a tendency for foaming and the like to easily occur. When the dispersion of the acrylic resin (A) is too low, the handleability tends to decrease. The lower limit of the degree of dispersion is usually 1.1 in terms of the limit of manufacture.

[Method for producing acrylic resin (A)] In the third aspect, the acrylic resin (A) can be produced by polymerizing the copolymerization component (a) containing branched alkyl (meth)acrylate (a1). manufacture. The copolymerization component (a) of the third aspect may further contain optional polymerization components of hydroxyalkyl (meth)acrylate (a2), (meth)acrylate monomer (a3), ethylenically unsaturated monomer ( a4).

As a polymerization method of an acrylic resin (A), conventionally well-known polymerization methods, such as solution polymerization, suspension polymerization, block polymerization, and emulsion polymerization, are mentioned, for example. In view of the safety and stability of the reaction, and the point that the acrylic resin (A) can be produced with any monomer composition, solution polymerization is preferred. One example of a preferable manufacturing method of the acrylic resin (A) of the third aspect is shown below.

For example, solution polymerization can be performed by mixing or dropping the copolymerization component (a) and the polymerization initiator of the third aspect in an organic solvent. Examples of organic solvents used in the polymerization reaction include aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as n-hexane; esters such as methyl acetate, ethyl acetate, and butyl acetate; methanol and ethanol , n-propanol, isopropanol and other aliphatic alcohols; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and other ketones; dimethyl ether, diethyl ether and other aliphatic ethers; dichloro Aliphatic halogenated hydrocarbons such as methane and dichloroethane; cyclic ethers such as tetrahydrofuran, etc. Among them, esters and ketones are preferred, and ethyl acetate, acetone, and methyl ethyl ketone are particularly preferred. One type of organic solvent may be used alone, or two or more types may be used in combination.

As a polymerization initiator used in the polymerization reaction, an azo-based polymerization initiator or a peroxide-based polymerization initiator or the like which is a general radical polymerization initiator can be used. Examples of the azo polymerization initiator include: 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobisisobutyronitrile, (1-phenylethyl ) azodiphenylmethane, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-cyclopropylpropionitrile), 2,2' -Azobis(4-methoxy-2,4-dimethylvaleronitrile) and the like.

As peroxide-based polymerization initiators, for example, benzoyl peroxide, di-tert-butyl peroxide, cumene hydroperoxide, lauryl peroxide, pivalic acid peroxide third Butyl ester, tertiary hexyl peroxypivalate, tertiary hexyl peroxyneodecanoate, diisopropyl peroxycarbonate, diisobutyryl peroxide, etc.

Among them, azo-based polymerization initiators are preferred, and 2,2'-azobisisobutyronitrile, 2,2'-azobis(4-methoxy-2,4-dimethylpentane nitrile). A polymerization initiator may be used alone or in combination of two or more.

The amount of the polymerization initiator used is usually 0.001 to 10 parts by weight, preferably 0.1 to 8 parts by weight, more preferably 0.5 to 6 parts by weight, and most preferably 1 to 4 parts by weight relative to 100 parts by weight of the copolymerization component (a). The weight part is more preferably 1.5 to 3 weight parts, most preferably 2 to 2.5 weight parts. When the usage-amount of a polymerization initiator is too small, since the polymerization rate of acrylic resin (A) will fall, there exists a tendency for the residual monomer to increase. Moreover, there exists a tendency for the weight average molecular weight of an acrylic resin (A) to improve. If the amount of the polymerization initiator used is too large, the acrylic resin (A) tends to gel.

The polymerization conditions of the solution polymerization are not particularly limited, and the polymerization can be carried out according to previously known polymerization conditions. For example, the copolymerization component (a) and the polymerization initiator can be mixed or dropped in an organic solvent to perform polymerization.

The polymerization temperature in the polymerization reaction is usually 40 to 120°C, and is preferably 50 to 90°C in terms of stable reaction. When the polymerization temperature is too high, the acrylic resin (A) tends to be easily gelled. If the polymerization temperature is too low, the activity of the polymerization initiator decreases, so the polymerization rate decreases, and as a result, the residual monomer tends to increase.

The polymerization time in the polymerization reaction is not particularly limited, and is at least 0.5 hours from the last addition of the polymerization initiator, preferably at least 1 hour, more preferably at least 2 hours, and most preferably at least 5 hours. The polymerization reaction is preferably performed while refluxing the solvent in terms of ease of heat removal.

(Photoinitiator (B)) The photoinitiator (B) of the third aspect contains an intramolecular hydrogen abstraction type photoinitiator (b1) and an intermolecular hydrogen abstraction type photoinitiator (b2). The photoinitiator (B) of the third aspect may further contain an intramolecular hydrogen abstraction type photoinitiator (b1) and an intermolecular hydrogen abstraction type photoinitiator as long as the effect of the invention is not impaired Other photoinitiators (b3) other than (b2).

[Intramolecular hydrogen abstraction type photoinitiator (b1)] As the third aspect of the intramolecular hydrogen abstraction type photoinitiator (b1), for example: oxy-phenyl-acetic acid 2-[2- Oxy-2-phenyl-acetyloxy-ethoxy]-ethyl ester and a mixture of oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester, benzoyl Methyl formate, etc. Among them, oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetyloxy-ethoxy is preferred in terms of crosslinking efficiency when completely hardened. ]-ethyl ester and a mixture of oxy-phenyl-acetic acid 2-[2-hydroxy-ethoxy]-ethyl ester. Commercially available products include "Omnirad 754" and "Omnirad MBF" manufactured by IGM RESINS B.V., for example.

[Intermolecular hydrogen abstraction type photoinitiator (b2)] As the third aspect of intermolecular hydrogen abstraction type photoinitiator (b2), for example: benzophenone, 4-methyl-diphenyl Methanone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 4-(methyl ) acryloxybenzophenone, 4-[2-((meth)acryloxy)ethoxy]benzophenone, 4-(meth)acryloxy-4'-methoxy benzophenone, carboxymethoxymethoxybenzophenone-polyethylene glycol 250 diester, etc. Among these, 2,4,6-trimethylbenzophenone is preferable at the point that it is liquid and easy to handle. Also, in terms of enabling high cross-linking, 4-(meth)acryloxybenzophenone, 4-[2-((methyl) Acryloxy)ethoxy]benzophenone, 4-(meth)acryloxy-4'-methoxybenzophenone, carboxymethoxymethoxybenzophenone-polyethylene Diol 250 diester. Commercially available products include "MBP" manufactured by Shinryo Corporation, "Omnirad BP" manufactured by IGM RESINS B.V., "Omnirad 4MBZ", "Esacure TZT" and "Omnipol BP".

、4-異丙基-9-氧硫𠮿

、2,4-二乙基-9-氧硫𠮿

、2,4-二氯9-氧硫𠮿

、1-氯-4-丙氧基-9-氧硫𠮿

、2-(3-二甲胺基-2-羥基)-3,4-二甲基-9H-9-氧硫𠮿

-9-酮內消旋氯化物等9-氧硫𠮿

類；  2,4,6-三甲基苯甲醯基-二苯基氧化膦、雙(2,6-二甲氧基苯甲醯基)-2,4,4-三甲基-戊基氧化膦、雙(2,4,6-三甲基苯甲醯基)-苯基氧化膦等醯基氧化膦類。[Other photoinitiators (b3)] As other photoinitiators (b3) of the third aspect, for example: oxyphenyl- 2-[2-oxo-2-phenylacetyloxyethoxy]ethyl acetate; Diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1- Ketone, benzoyl dimethyl ketal, 4-(2-hydroxyethoxy) phenyl-(2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl- 2-Morpholinyl (4-thiomethylphenyl) propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl) butanone, 2-hydroxy- 2-Methyl-1-[4-(1-methylvinyl)phenyl]acetone oligomers and other acetophenones; Benzoin, Benzoin Methyl Ether, Benzoin Ethyl Ether, Benzoin Isopropyl Ether, Benzoin Isobutyl Ether, etc. Benzoins; 2-isopropyl-9-oxothio𠮿

, 4-isopropyl-9-oxothio𠮿

, 2,4-Diethyl-9-oxothio𠮿

, 2,4-dichloro-9-oxosulfur 𠮿

, 1-Chloro-4-propoxy-9-oxosulfur

、2-(3-Dimethylamino-2-hydroxyl)-3,4-dimethyl-9H-9-oxosulfur 𠮿

-9-keto meso chloride etc. 9-oxosulfur 𠮿

class; 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentyl Acylphosphine oxides such as phosphine oxide and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

、2,4-二異丙基-9-氧硫𠮿

等。  光起始劑(B)之助劑可單獨使用1種，亦可併用2種以上。As an auxiliary agent of the photoinitiator (B) of the third aspect, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michelerone), 4,4'-Diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, ethyl 4-dimethylaminobenzoate, 4-dimethylaminobenzoic acid (n-butoxy) Ethyl ester, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethyl-9-oxothiol

, 2,4-Diisopropyl-9-oxosulfur

wait. The auxiliaries of the photoinitiator (B) may be used alone or in combination of two or more.

(Crosslinking Agent (C)) The adhesive composition of the third aspect preferably further contains a crosslinking agent (C) in addition to the acrylic resin (A) and the photoinitiator (B). The crosslinking agent (C) may, for example, be an active energy ray crosslinking agent (c1) or a thermal crosslinking agent (c2). The active energy ray crosslinking agent (c1) and thermal crosslinking agent (c2) can be used alone or in combination of two or more.

In the case of containing only the active energy ray crosslinking agent (c1) as the crosslinking agent (C), multistage hardening can be achieved only by controlling the amount of active energy ray. Also, when the active energy ray crosslinking agent (c1) and the thermal crosslinking agent (c2) are contained as the crosslinking agent (C), multistage curing can also be achieved by using thermal curing and active energy ray curing together. By controlling the cross-linking reaction in the above-mentioned manner, the cohesive force of the adhesive layer as a whole can be adjusted, and stable adhesive properties can be obtained after one hardening or after complete hardening.

[Active energy ray crosslinking agent (c1)] Examples of the active energy ray crosslinking agent (c1) include monofunctional crosslinking agents containing one ethylenically unsaturated group in one molecule, and two or more in one molecule. Polyfunctional crosslinking agent for ethylenically unsaturated groups. Among them, polyfunctional crosslinking agents are preferred.

As a multifunctional crosslinking agent, for example, hexanediol di(meth)acrylate, butanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1 ,10-decanediol di(meth)acrylate, (poly)ethylene glycol mono(meth)acrylate, (poly)butylene glycol mono(meth)acrylate, (poly)ethylene glycol di( Meth)acrylate, (poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate, (poly)pentamethylene glycol di(meth)acrylate ester, (poly) hexamethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, di Pentaerythritol hexa(meth)acrylate, trimethylolpropane tri(meth)acrylate, EO modified trimethylolpropane tri(meth)acrylate, glycerin tri(meth)acrylate, EO modified Glycerin tri(meth)acrylate, Tetramethylolmethane tri(meth)acrylate, Isocyanuric acid ethylene oxide modified tri(meth)acrylate, Allyl (meth)acrylate, Vinyl (meth)acrylate, urethane (meth)acrylate, etc. Among them, in terms of the balance of adhesive properties after hardening, (meth)acrylates containing two ethylenically unsaturated groups are preferred, and (poly)ethylene glycol di(meth)acrylate is particularly preferred. , (poly)propylene glycol di(meth)acrylate, (poly)tetramethylene glycol di(meth)acrylate. The polyfunctional crosslinking agent may be used alone or in combination of two or more.

[Thermal crosslinking agent (c2)] The thermal crosslinking agent (c2) can exert excellent adhesion mainly by reacting with the functional group derived from the functional group-containing monomer as the constituent monomer of the acrylic resin (A). force. Examples include: isocyanate-based crosslinking agent (c2-1), epoxy-based crosslinking agent (c2-2), aziridine-based crosslinking agent (c2-3), melamine-based crosslinking agent (c2-4 ), aldehyde crosslinking agent (c2-5), amine crosslinking agent (c2-6), metal chelate crosslinking agent (c2-7). Among them, an isocyanate-based crosslinking agent (c2-1) can be suitably used in order to improve the adhesion to the substrate or the reactivity with the acrylic resin (A). The thermal crosslinking agent (c2) can be used alone or in combination of two or more.

Examples of the isocyanate-based crosslinking agent (c2-1) include toluene diisocyanate-based compounds such as 2,4-toluene diisocyanate and 2,6-toluene diisocyanate; 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, tetramethylxylylene diisocyanate and other xylylene diisocyanate compounds; 1,5-naphthalene diisocyanate, triphenylmethane triisocyanate and other aromatic isocyanate compounds ; Hexamethylene diisocyanate, trimethylhexamethylene diisocyanate and other hexamethylene diisocyanate compounds or lysine diisocyanate and other aliphatic isocyanate compounds; Alicyclic isocyanate such as isophorone diisocyanate compounds; adducts of these isocyanate compounds and polyol compounds such as trimethylolpropane; biuret or isocyanurate forms of these isocyanate compounds, etc.

Among the isocyanate-based crosslinking agents (c2-1), it is preferable to use an aromatic isocyanate-based compound, particularly preferably a toluene diisocyanate-based compound, since it is excellent in reactivity. Moreover, it is preferable to use an aliphatic isocyanate type compound from the viewpoint of yellowing suppression, and a hexamethylene diisocyanate type compound is especially preferable.

As the epoxy-based crosslinking agent (c2-2), for example, bisphenol A-epichlorohydrin type epoxy resin, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol di Glycidyl ether, glycerol triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether Glyceryl erythritol, diglycerol polyglycidyl ether, etc.

Examples of the aziridine-based crosslinking agent (c2-3) include: tetramethylolmethane-tri-β-aziridinyl propionate, trimethylolpropane-tri-β-aziridine propionate, N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxyamide), N,N'-hexamethylene-1,6-bis(1- Aziridine carboxamide), etc.

As the melamine-based crosslinking agent (c2-4), for example, hexamethoxymethylmelamine, hexaethoxymethylmelamine, hexapropoxymethylmelamine, hexabutoxymethylmelamine, hexapentylmelamine, Oxymethylmelamine, hexahexyloxymethylmelamine, melamine resin, etc.

As an aldehyde crosslinking agent (c2-5), glyoxal, malondialdehyde, succinaldehyde, maleic dialdehyde, glutaraldehyde, formaldehyde, acetaldehyde, benzaldehyde, etc. are mentioned, for example.

Examples of the amine-based crosslinking agent (c2-6) include hexamethylenediamine, triethylenediamine, polyethyleneimine, hexamethylenetetramine, and diethylenetriamine. , triethylenetetramine, isophorone diamine, amino resin, polyamide, etc.

Examples of the metal chelate crosslinking agent (c2-7) include acetylene of polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. Acetone or acetyl acetyl ester coordination compounds, etc.

(Silane Coupling Agent (D)) The adhesive composition of the third aspect preferably further contains a silane coupling agent (D) as an acrylic resin (A), a photoinitiator ( Compounds other than B) and the crosslinking agent (C).

The silane coupling agent (D) is an organosilicon compound containing one or more reactive functional groups and an alkoxy group bonded to a silicon atom in its structure. Monomer type and oligomer type are mentioned as a silane coupling agent (D).

As a reactive functional group in a silane coupling agent (D), an epoxy group, (meth)acryl group, a mercapto group, a hydroxyl group, a carboxyl group, an amine group, an amide group, an isocyanate group etc. are mentioned, for example. Among them, epoxy group and mercapto group are preferable in terms of durability and secondary processability.

The content ratio of the reactive functional group in the silane coupling agent (D) is preferably 3,000 g/mol or less, more preferably 1,500 g/mol or less, further preferably 1,000 g/mol or less. When the reactive functional group is within the above numerical range, the balance between durability and secondary workability improves. The lower limit of the content ratio of the reactive functional group in the silane coupling agent (D) is 200 g/mol.

The alkoxy group bonded to the silicon atom in the silane coupling agent (D) is preferably an alkoxy group having 1 to 8 carbon atoms in terms of durability and storage stability. Among them, methoxy and ethoxy are more preferable. The silane coupling agent (D) may also have a reactive functional group and an organic functional group other than an alkoxy group bonded to a silicon atom, such as an alkyl group or a phenyl group.

As the silane coupling agent (D), for example, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane, γ-shrink Glyceryloxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropylmethyl Dimethoxysilane, Methyltri(glycidyl)silane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethylsilane Oxysilane etc. Among them, in terms of heat resistance, γ-glycidoxypropyltrimethoxysilane is preferred. Silane coupling agent (D) can be used alone or in combination of two or more.

(Carbodiimide compound (E)) The adhesive composition of the third aspect preferably further contains a carbodiimide compound (E) as the acrylic resin (A) in terms of heat resistance. ), photoinitiator (B), crosslinking agent (C) and silane coupling agent (D). As the carbodiimide-based compound (E), for example, bis(2,6-diisopropylphenyl)carbodiimide, dicyclohexylcarbodiimide, diisopropylcarbodiimide, Diimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, tert-butylisopropylcarbodiimide, diphenylcarbon Monocarbodiimides such as diimide, di-tert-butylcarbodiimide, bis(dodecyl)carbodiimide, etc.; polycarbodiamides with plural carbodiimides present imine or cyclic carbodiimide, etc. Among them, in terms of heat resistance, monocarbodiimide-based compounds are preferred, and bis(2,6-diisopropylphenyl)carbodiimide is further preferred. The carbodiimide compound (E) may be used alone or in combination of two or more.

(Optional Component) The adhesive composition of the third aspect may contain an adhesive as another optional component as needed. The adhesive composition of the third aspect may contain previously known additives such as crosslinking accelerators, antistatic agents, adhesion imparting agents, and functional pigments.

(Composition of Adhesive Composition) In the third aspect, the content of the acrylic resin (A) is preferably at least 80% by weight, more preferably 90 to 99.9% by weight, and even more preferably Preferably, it is 92 to 99.9% by weight. When the content of the acrylic resin (A) is within the above numerical range, it is easy to obtain an adhesive sheet exhibiting excellent adhesive properties in a low-crosslinked state after primary curing.

In the third aspect, the content of the photoinitiator (B) is preferably 0.01-10 parts by weight, more preferably 0.1-5.0 parts by weight, and even more preferably 100 parts by weight of the acrylic resin (A). 0.5 to 3.0 parts by weight. If the content of the photoinitiator (B) is within the above numerical range, sufficient curability can be obtained when fully cured.

In the third aspect, the content of the intramolecular hydrogen abstraction photoinitiator (b1) is preferably 0.01-10 parts by weight, more preferably 0.1-5.0 parts by weight relative to 100 parts by weight of the acrylic resin (A) . If the content of the hydrogen-abstracting photoinitiator (b1) in the molecule is too high, the adhesive force after complete hardening tends to decrease. If the content of the intramolecular hydrogen-abstracting photoinitiator (b1) is too small, the adhesive properties at low crosslinking degrees tend to be poor.

In the third aspect, the content of the intermolecular hydrogen abstraction type photoinitiator (b2) is preferably 0.01-10 parts by weight, more preferably 0.1-5.0 parts by weight relative to 100 parts by weight of the acrylic resin (A) . If the content of the intermolecular hydrogen abstraction type photoinitiator (b2) is too much, the adhesive force after complete hardening tends to decrease. If the content of the intermolecular hydrogen-abstracting photoinitiator (b2) is too small, the adhesive properties at low crosslinking degrees tend to be poor.

In the third aspect, when the adhesive composition contains a crosslinking agent (C), the content of the crosslinking agent (C) is usually preferably 20 parts by weight relative to 100 parts by weight of the acrylic resin (A) Below, it is more preferable that it is 0.001-15 weight part, and it is still more preferable that it is 0.1-10 weight part. If the content of the crosslinking agent (C) is too high, the adhesive force tends to decrease. If the content of the crosslinking agent (C) is too small, the adhesive properties under high temperature conditions tend to decrease.

In the third aspect, when the adhesive composition contains the active energy ray crosslinking agent (c1), the content of the active energy ray crosslinking agent (c1) is usually 100 parts by weight relative to the acrylic resin (A), Preferably it is 0.01-20 weight part, More preferably, it is 0.1-10 weight part, More preferably, it is 0.5-7.5 weight part. If the content of the active energy ray crosslinking agent (c1) is too small, sufficient durability may not be obtained due to insufficient cohesive force. When the content of the active energy ray crosslinking agent (c1) is too large, the adhesive property at the time of primary curing tends to decrease.

In the third aspect, when the adhesive composition contains a thermal crosslinking agent (c2), the content of the thermal crosslinking agent (c2) is usually 0.001 parts by weight relative to 100 parts by weight of the acrylic resin (A). -5 parts by weight, more preferably 0.02-1 part by weight, still more preferably 0.05-0.5 parts by weight. If the content of the thermal crosslinking agent (c2) is too small, the cohesive force will be insufficient and the adhesive properties will tend to decrease during primary hardening. If the content of the thermal crosslinking agent (c2) is too high, the adhesive force tends to decrease when fully hardened.

In the third aspect, it is preferable to use an active energy ray crosslinking agent (c1) and a thermal crosslinking agent (c2) together as the crosslinking agent (C). When used in combination, the content ratio (c1/c2) of the active energy ray crosslinking agent (c1) to the thermal crosslinking agent (c2) is preferably 100/1 to 100/50 by weight ratio.

In the third aspect, when the adhesive composition contains the silane coupling agent (D), the content of the silane coupling agent (D) is preferably 0.001 to 3 parts by weight relative to 100 parts by weight of the acrylic resin (A) part, more preferably 0.005 to 1 part by weight, still more preferably 0.01 to 0.5 part by weight, especially preferably 0.015 to 0.3 part by weight. If the content of the silane coupling agent (D) is too small, it tends to be difficult to obtain the effect of improving durability. If the content of the silane coupling agent (D) is too high, the adhesive force tends to decrease due to effects such as bleeding.

In the third aspect, when the adhesive composition contains the carbodiimide compound (E), the content of the carbodiimide compound (E) is relative to 100 parts by weight of the acrylic resin (A) , preferably 0.01 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, further preferably 0.2 to 2 parts by weight, especially preferably 0.3 to 1 part by weight. If the content of the carbodiimide compound (E) is too small, the thermal stability of the acrylic resin (A) tends to decrease. When the content of the carbodiimide-based compound (E) is too high, durability tends to decrease due to effects such as bleeding.

In the third aspect, when other adhesives or additives are added to the adhesive combination, the content of other adhesives or additives is preferably 10 parts by weight or less with respect to 100 parts by weight of the acrylic resin (A), More preferably, it is 5 parts by weight or less.

(Preparation of Adhesive Composition) By mixing acrylic resin (A), photoinitiator (B), optional crosslinking agent (C), silane coupling agent (D), carbodiimide compound (E) Other optional ingredients are mixed to obtain the adhesive composition of the third aspect. The mixing method is not particularly limited, and the following various methods can be used: a method of mixing the ingredients at one time; a method of mixing the remaining ingredients one at a time or sequentially after mixing any of the ingredients.

(Applications) The adhesive composition of the third aspect can be suitably used as an adhesive for a multistage hardening adhesive sheet that is hardened in a plurality of stages. According to the adhesive composition of the third aspect, excellent adhesive properties can be obtained in terms of low tackiness to the touch and high constant load retention even in a low-crosslinked state after primary curing. After fully hardened, it not only has the usual adhesive properties such as adhesion, but also has excellent durability when laminating various types and shapes of components such as polarizing plates or glass.

The adhesive composition of the third aspect can also be continuously adhered to a complex shape under stress in a low cross-linked state after first curing, and can be fully cured thereafter. Therefore, it can be suitably used especially for the use of the adhesive agent used for a touch panel, an image display apparatus, etc., or an adhesive sheet.

<Adhesive> The adhesive of the third aspect is obtained by cross-linking the adhesive composition of the third aspect above. By crosslinking (curing) the adhesive composition of the third aspect, the acrylic resin (A) contained in the adhesive composition forms a crosslinked structure in at least one of intramolecular and intermolecular. As a result, the adhesive composition of the third aspect is cross-linked to become the adhesive of the third aspect. In the case where the acrylic resin (A) has an active energy ray crosslinkable structural site, a crosslinked structure can be formed by irradiation with active energy rays.

The adhesive of the third aspect exhibits multi-stage hardening that can be hardened in multiple stages. The adhesive of the third aspect is in a low cross-linking state by primary curing before complete curing. Complete hardening and primary hardening may not be clearly distinguished, for example, they can be distinguished based on the difference in gel fraction or dynamic viscoelasticity.

In any one of the primary hardening step and the complete hardening step, the hardening method is not particularly limited, and any one of heating or active energy ray irradiation may be used. In addition, one hardening step may be performed in plural times, or multi-step hardening may be performed in order to make it into a fully hardened state. The adhesive of the third aspect has excellent adhesive properties after primary curing, so it can be suitably used for lamination of optical components constituting touch panels or image display devices.

The adhesive of the third aspect can be considered to contain at least the cross-linked product of the acrylic resin (A) of the third aspect. The cross-linked product may be a partially cross-linked product in which at least a part of the acrylic resin (A) is partially cross-linked, or may be a fully cross-linked product in which all of the acrylic resin (A) is fully cross-linked. Moreover, the adhesive agent of the 3rd aspect may contain both the partially crosslinked thing and the fully crosslinked thing of an acrylic resin (A).

<Adhesive Sheet> The adhesive sheet of the third aspect has an adhesive layer containing the adhesive of the third aspect. The adhesive sheet of the third aspect may exhibit multi-stage hardening in which the adhesive layer hardens in multiple stages.

An adhesive sheet can be produced by disposing an adhesive layer containing the adhesive of the third aspect on a base sheet. Moreover, a double-sided adhesive sheet can be produced by providing an adhesive layer on a release sheet. Furthermore, an adhesive layer is formed on the release sheet instead of the substrate sheet, and the release sheet is attached to the adhesive layer on the opposite side, thereby also making a double-sided adhesive sheet without a substrate. It is also possible to further form an adhesive layer on the formed adhesive layer, and further form a thick-film adhesive layer. When the obtained adhesive sheet or double-sided adhesive sheet is used, the release sheet is peeled off from the adhesive layer for use.

As a method of producing the adhesive sheet of the third aspect, methods such as the following (i) and (ii) may be mentioned, for example. (i) A method of producing an adhesive sheet after applying a coating liquid obtained by dissolving the adhesive composition of the third aspect in a solvent. (ii) A method of producing an adhesive sheet after melting the adhesive composition of the third aspect by heating.

The method of (i) will be described. When preparing an adhesive sheet after applying a coating liquid obtained by dissolving the adhesive composition of the third aspect in a solvent, the amount of the adhesive composition containing the third aspect is adjusted with an appropriate organic solvent. The concentration of the coating solution is directly applied to the substrate sheet. Thereafter, it is dried by, for example, heat treatment at 80 to 105° C. for 0.5 to 10 minutes, and attached to a base material sheet or a release sheet. Thereafter, the adhesive composition is crosslinked (hardened) by active energy ray irradiation or aging to produce an adhesive sheet having an adhesive layer containing the adhesive.

As an organic solvent used for concentration adjustment, what was mentioned as the organic solvent used for the polymerization reaction of an acrylic resin (A) is mentioned. The concentration of the adhesive composition is usually 20 to 60% by weight, preferably 30 to 50% by weight, based on solid content.

The method of (ii) will be described. When the adhesive composition of the third aspect is melted by heating to form an adhesive sheet, by applying it to one or both sides of the base sheet in a melted state, and then cooling method or a method of extruding onto a base sheet through a T-die or the like for lamination, the adhesive layer is formed on one side or both sides of the base sheet so as to have a desired thickness. Then, if necessary, attach a release sheet to the adhesive layer, thereby producing an adhesive sheet.

In addition, after forming the adhesive layer on the base sheet, if necessary, it is subjected to active energy ray irradiation treatment, and aging is performed, whereby an adhesive sheet having an adhesive layer formed by hardening (crosslinking) the adhesive composition can be produced. material. Furthermore, the adhesive layer is formed on the release sheet, and the release sheet is attached to the adhesive layer on the opposite side, so that a double-sided adhesive sheet without a substrate can also be produced. The obtained adhesive sheet or double-sided adhesive sheet is used by peeling the release sheet from the adhesive layer during use.

As the base sheet, for example, polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate/isophthalic acid Polyester resins such as ethylene glycol copolymer; polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; polyvinyl fluoride, polyvinylidene fluoride, polyfluoroethylene, etc. Polyfluoroethylene resin; nylon 6, nylon 6,6 and other polyamides; polyvinyl chloride, polyvinyl chloride/vinyl acetate copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polyethylene Vinyl polymers such as alcohol and vinylon; Cellulose resins such as cellulose triacetate and celluloid; Acrylic resins such as polymethyl methacrylate, polyethyl methacrylate, polyethyl acrylate, and polybutyl acrylate Resin; polystyrene; polycarbonate; polyarylate; polyimide and other synthetic resin sheets; aluminum, copper, iron and other metal foils; high-grade paper, cellophane and other paper; including glass fiber, natural fiber, synthetic fiber, etc. woven or non-woven fabrics. These base sheets may be used as a single layer body or as a multilayer body in which two or more types are laminated. Among them, a synthetic resin sheet is preferable in terms of weight reduction and the like.

As the release sheet, for example, those obtained by subjecting various synthetic resin sheets, paper, woven fabrics, non-woven fabrics, etc. to the base sheet to a release treatment can be used. As the release sheet, for example, a silicon-based release sheet is preferably used.

The application method of the adhesive composition is not particularly limited. For example, methods such as roll coating, die coating, gravure coating, chipped wheel coating, slit coating, and screen printing may be mentioned.

As active energy rays, rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, and infrared rays; electromagnetic waves such as X-rays and γ-rays; electron beams; proton beams; neutron rays, etc., can be used. Curing using ultraviolet rays is preferred in terms of curing speed, availability of irradiation equipment, price, and the like.

Regarding the gel fraction before the adhesive layer of the adhesive sheet is completely hardened, regardless of the shape of the adherend, it is easy to stick and the adhesive layer can hold the adherend after sticking. , preferably 0.1 to 60% by weight, more preferably 1 to 50% by weight, especially preferably 5 to 45% by weight.

With regard to the gel fraction after the adhesive layer of the adhesive sheet is completely hardened, it is preferably 50 to 95% by weight, more preferably 55 to 90% by weight, and especially preferably 60 to 85% by weight. When the gel fraction is too low, durability tends to decrease due to decreased cohesive force. If the gel fraction is too high, there is a tendency for the adhesive force to decrease due to the increase in the cohesive force.

The gel fraction can be appropriately adjusted by the following method, for example.・Adjust the dose of active energy rays.・Adjust the content of the active energy ray cross-linking structure in the acrylic resin (A).・Adjust the type or amount of photoinitiator (B) and crosslinking agent (C).

The gel fraction serves as a standard for the degree of crosslinking (degree of hardening), and can be calculated, for example, by the following method. That is, an adhesive sheet formed by wrapping a polymer sheet (such as a polyethylene terephthalate (PET) film, etc.) as a base material with a 200 mesh SUS wire mesh to form an adhesive layer (not shown For those with a release sheet), dip in toluene maintained at 23°C for 24 hours, and use the weight percentage of the insoluble adhesive components remaining in the wire mesh as the gel fraction. However, it is calculated by subtracting the weight of the substrate from the weight before and after dissolving toluene.

The thickness of the adhesive layer of the adhesive sheet is usually preferably from 50 to 3000 μm, more preferably from 75 to 1000 μm, and especially preferably from 100 to 350 μm. When the thickness of the adhesive layer is too thin, the impact absorption tends to decrease. When the thickness of the adhesive layer is too thick, for example, when sticking to an optical member, the overall thickness increases and the practicability tends to decrease.

The thickness of the adhesive layer is obtained by subtracting the measured value of the thickness of the constituent members other than the adhesive layer from the measured value of the thickness of the entire laminate including the adhesive layer using "ID-C112B" manufactured by Mitutoyo Co., Ltd. value.

The adhesive layer of the adhesive sheet according to the third aspect preferably has a haze value of 2% or less when the thickness of the adhesive layer is 100 μm, more preferably 0-1.5%, especially preferably 0-1% . When the haze value is too high, the pressure-sensitive adhesive layer tends to become white and reduce transparency. The haze value is measured by using HAZE MATER NDH4000 (manufactured by Nippon Denshoku Industries Co., Ltd.) to measure the diffuse transmittance and total light transmittance, and substitute the obtained values of diffuse transmittance (DT) and total light transmittance (TT) into the following [Formula 1] and calculated. This machine complies with JIS K7361-1. Haze value (%)＝(DT/TT)×100・・・[Formula 1]

In the third aspect, an optical member with an adhesive layer attached can be obtained by forming an adhesive laminated layer on the optical member. For example, after the adhesive layer of the adhesive sheet of the third aspect in which the adhesive layer is formed on the release sheet is attached to the optical member, the release sheet is peeled off, thereby obtaining an optical device with an adhesive layer. member. Moreover, optical members can also be bonded together using the said double-sided adhesive sheet.

The optical member may, for example, be a member constituting a touch panel or an image display device. For example, a display (organic EL, liquid crystal), a transparent conductive film substrate (ITO substrate), a protective film (glass), a transparent antenna (film), a transparent wiring, etc. are mentioned.

Preferred implementations of the third aspect described above include the following [C1] to [C6], but are not limited thereto. [C1] An adhesive composition comprising an acrylic resin (A) and a photoinitiator (B), wherein the acrylic resin (A) is a homopolymer with a glass transition temperature of -30°C or higher ( The polymerization product of the copolymerization component (a) of branched alkyl meth)acrylate (a1), the above-mentioned acrylic resin (A) having a glass transition temperature based on dynamic viscoelasticity of -10°C or higher, the above-mentioned acrylic resin (A) ) has a weight average molecular weight of 400,000 or less, and the photoinitiator (B) includes an intramolecular hydrogen abstraction type photoinitiator (b1) and an intermolecular hydrogen abstraction type photoinitiator (b2). [C2] The adhesive composition as described in [C1], which further contains a crosslinking agent (C). [C3] An adhesive obtained by cross-linking the adhesive composition described in [C1] or [C2]. [C4] The adhesive described in [C3], wherein the crosslinking is performed by irradiation of active energy rays. [C5] An adhesive sheet having an adhesive layer containing the adhesive described in [C3] or [C4]. [C6] The adhesive sheet as described in [C5], wherein the above-mentioned adhesive layer is multistage hardening that is hardened in a plurality of stages.

Preferred embodiments of the present invention include the following [1] to [26], but are not limited thereto. [1] An adhesive composition comprising an acrylic resin (A) and a photoinitiator (B), wherein the acrylic resin (A) is a polymerization product of the following copolymerization component (a), the copolymerization component (a ) contains an alkyl acrylate (a1) whose glass transition temperature when forming a homopolymer is -30 to 50°C and an alkyl methacrylate (a2) whose glass transition temperature when forming a homopolymer is -10 to 120°C ), the total content of the above-mentioned alkyl acrylate (a1) and the above-mentioned alkyl methacrylate (a2) is 5% by weight or more with respect to 100% by weight of the above-mentioned copolymerization component (a). [2] The adhesive composition according to [1], wherein the copolymerization component (a) further contains a hydroxyl group-containing monomer (a3). [3] The adhesive composition according to [2], wherein the content of the hydroxyl group-containing monomer (a3) is 0.1% by weight or more based on 100% by weight of the copolymerization component (a). [4] The adhesive composition according to any one of [1] to [3], wherein the acrylic resin (A) has a glass transition temperature based on dynamic viscoelasticity of -10°C or higher. [5] The adhesive composition according to any one of [1] to [4], wherein the acrylic resin (A) has a weight average molecular weight of 50,000 to 500,000. [6] The adhesive composition according to any one of [1] to [5], wherein the acrylic resin (A) has a weight average molecular weight of 50,000 to 400,000. [7] The adhesive composition according to any one of [1] to [6], wherein the weight ratio of the alkyl acrylate (a1) to the alkyl methacrylate (a2) is 5/95 ~55/45. [8] The adhesive composition as described in any one of [1] to [7], wherein the total content of the above-mentioned alkyl acrylate (a1) and the above-mentioned alkyl methacrylate (a2) is Component (a) is 30 to 70% by weight. [9] The adhesive composition as described in any one of [1] to [8], wherein the above-mentioned copolymerization component (a) further includes a hydroxyl-containing monomer containing an alkyl chain, a hydroxyl group, and an ethylenically unsaturated group ( a4). [10] The adhesive composition described in any one of [1] to [9], wherein the average carbon number of the alkyl chain of the hydroxyl group-containing monomer (a3) in the copolymerization component (a) is 2.1 above. [11] The adhesive composition according to any one of [1] to [10], wherein any one of the above-mentioned alkyl acrylate (a1) and the above-mentioned alkyl methacrylate (a2) contains branched chain alkyl. [12] The adhesive composition according to any one of [1] to [11], wherein the photoinitiator (B) contains an intramolecular hydrogen abstraction type photoinitiator (b1) or an intermolecular hydrogen abstraction Type photoinitiator (b2). [13] The adhesive composition as described in any one of [1] to [12], wherein the photoinitiator (B) contains an intramolecular hydrogen abstraction type photoinitiator (b1) and an intermolecular hydrogen abstraction Type photoinitiator (b2). [14] The adhesive composition according to any one of [1] to [13], further comprising a crosslinking agent (C). [15] An adhesive obtained by cross-linking the adhesive composition according to any one of [1] to [14]. [16] The adhesive as described in [15], wherein the crosslinking is performed by irradiation of active energy rays. [17] An adhesive sheet having an adhesive layer comprising the adhesive described in [15] or [16]. [18] The adhesive sheet according to [17], wherein the adhesive layer is multi-stage curable in which the adhesive layer is cured in a plurality of stages. [19] An adhesive sheet with a release film, which has a laminated structure in which at least one side of the adhesive sheet as described in [17] or [18] is layered with a release film. [20] A laminate for an image display device, comprising a laminate structure in which two image display device constituent members are laminated via the adhesive sheet as described in [17] or [18], the two image display One of the device constituent members is a cover glass having a curved shape, and the other of the above two image display device constituent members is selected from a touch sensor, an image display panel, a surface protection film, and an antireflection film. , at least one of the group consisting of color filters, polarizing films, and retardation films. [21] A curved image display device comprising the laminate for an image display device as described in [20]. [22] An adhesive composition for a curved optical member, comprising an acrylic resin (A), wherein the acrylic resin (A) is a polymerization product of the following copolymerization component (a), and the copolymerization component (a) contains an acrylic alkylene Alkyl ester (a1) and alkyl methacrylate (a2). [23] The adhesive composition for curved optical members according to [22], wherein the copolymerization component (a) further contains a hydroxyl group-containing monomer (a3). [24] The adhesive composition for curved optical members according to [22] or [23], wherein the weight ratio of the alkyl acrylate (a1) to the alkyl methacrylate (a2) is 5/95 ~55/45. [25] The adhesive composition for a curved optical member according to any one of [22] to [24], wherein the total content of the alkyl acrylate (a1) and the alkyl methacrylate (a2) is It is 10 weight% or more with respect to the said copolymerization component (a). [26] The adhesive composition for a curved optical member according to any one of [22] to [25], further comprising a photopolymerization initiator.

As mentioned above, although specific embodiment was illustrated and described about each aspect of this invention, each embodiment was presented as an example and does not limit the scope of this invention. The aspects described in this specification and their implementations can be modified in various ways within the scope of exerting the effects of the invention, and can be combined with the features disclosed in the description of other aspects within the scope of implementation. [Example]

[Example and Comparative Example of the First Aspect] Hereinafter, although the Example and the comparative example which are the 1st aspect of this invention are demonstrated concretely, this invention is not limited to the following description. In the example, "part" and "%" mean a weight basis. Also, the weight average molecular weight of the acrylic resin (A), the measurement of the glass transition temperature based on dynamic viscoelasticity, the thickness of the adhesive layer, and the haze value (%) are described in accordance with the above-mentioned embodiment of the first aspect. method to measure.

＜Abbreviation, Raw Material＞ (Alkyl Acrylate (a1)) ・MA: Methyl Acrylate (Tg of Homopolymer: 8℃) ・tBA: Tertiary Butyl Acrylate (Tg of Homopolymer: 41℃)

(Alkyl Methacrylate (a2)) ・MMA: Methyl Methacrylate (Tg of Homopolymer: 105℃) ・EMA: Ethyl Methacrylate (Tg of Homopolymer: 65℃) ・IBMA: Isobutyl methacrylate (Tg of homopolymer: 48°C)

(Hydroxyl-containing monomer (a3)) ・4HBA: 4-hydroxybutyl acrylate ・HEA: 2-hydroxyethyl acrylate

(Ethylenically unsaturated monomer (a4)) ・2EHA: 2-ethylhexyl acrylate (Tg of homopolymer: -70°C)

・ADVN: 2,2'-azobis(2,4-dimethylvaleronitrile) (10-hour half-life temperature 52°C)

(Photoinitiator (B)) [Intramolecular hydrogen abstraction type photoinitiator (b1)] ・Omnirad 754: A product manufactured by IGM Resins B.V. [Intermolecular hydrogen abstraction type photoinitiator (b2)] ・Esacure TZT: Products manufactured by IGM Resins B.V. ・MBP: Products manufactured by Shinryo Corporation

(Crosslinking agent (C)) ・Polypropylene glycol #400 diacrylate (NK ester APG400, manufactured by Shin-Nakamura Chemical Co., Ltd.)

(Silane coupling agent (D)) ・KBM403 (manufactured by Shin-Etsu Chemical Co., Ltd.)

<Production Example A1: Production of Acrylic Resin (A-A1)> EMA: 35 parts, MA: 10 parts, 4HBA: 5 parts, HEA: 10 parts, 2EHA: 40 parts were mixed to prepare a monomer solution. Into a 2 L flask with a cooler, put ethyl acetate as a polymerization solvent: 18 parts (boiling point 77°C), methyl ethyl ketone: 18 parts (boiling point 80°C), ADVN as a polymerization initiator: 0.01 Parts, 10% of 100 parts of the pre-mixed monomer solution, after heating to reflux in the flask, add ethyl acetate: 10 parts, ADVN: 0.18 parts, and the remaining 90 parts of the above-mentioned monomer solution %. Furthermore, after dripping for 30 minutes, the mixture of ethyl acetate: 10 parts and ADVN: 0.13 parts was dripped and reacted over 1 hour, and the solution of an acrylic resin (A-A1) was obtained. Table 1 shows the measurement results of the weight average molecular weight (Mw), degree of dispersion, and glass transition temperature based on dynamic viscoelasticity of the acrylic resin (A-A1).

<Production Examples A2 to A6, Comparative Production Examples A1 and A2> The composition of the copolymerization component including the monomer solution was set as shown in Table 1, and the acrylic resin (A -A2) to acrylic resin (A-A6), acrylic resin (A'-A1), acrylic resin (A'-A2). Table 1 shows the measurement results of the weight average molecular weight (Mw), degree of dispersion, and glass transition temperature based on dynamic viscoelasticity of each acrylic resin.

[Table 1] acrylic resin Copolymer composition (parts) (a1)/(a2) Mw (×10 ⁴ ) Dispersion Glass transition temperature (°C) MA (a1) (Tg: 8°C) tBA (a1) (Tg: 41°C) EMA (a2) (Tg: 65°C) MMA (a2) (Tg: 105°C) IBMA (a2) (Tg: 48°C) 4HBA (a3) HEA (a3) 2EHA (a4) (Tg: -70°C) (A-A1) 10 - 35 - - 5 10 40 22/78 twenty one 2.57 4 (A-A2) 15 - 35 - - 15 - 35 30/70 twenty three 2.99 5 (A-A3) 15 - 25 - - - 15 45 37.5/62.5 25 2.94 -3 (A-A4) 10 - - 25 - - 15 50 28.6/71.4 20 2.75 3 (A-A5) 15 - - - 35 - 15 35 30/70 twenty two 3.02 4 (A-A6) - 10 35 - - - 15 40 22/78 19 2.60 8 (A'-A1) 25 - - - - - 15 60 100/0 12 2.59 -15 (A'-A2) 30 - - - 5 - 15 50 85.7/14.3 20 3.00 -11

<Example A1> For 100 parts of acrylic resin (A-A1) solution (solid content conversion), Omnirad 754: 2.0 parts (solid content conversion), Esacure TZT: 1.0 parts (solid content conversion) , Polypropylene glycol #400 diacrylate: 5.0 parts (solid content conversion), KBM403: 0.1 part (solid content conversion) were mixed, and the adhesive composition was obtained. Adjust the obtained adhesive composition with ethyl acetate to a solid content concentration of 45%, apply it on a polyester release sheet so that the thickness after drying becomes about 50 μm, and dry it at 100°C for 5 minutes. An adhesive composition layer is formed.

Prepare two polyester-based release sheets on which the adhesive composition layer was formed as described above, and laminate the two adhesive composition layers facing each other. In the state where both sides of the laminated adhesive composition layer are sandwiched by polyester release sheets, the peak illuminance: 150 mW/cm ² and the cumulative exposure amount: 1000 mJ/cm are used by a high-pressure mercury UV irradiation device. ² (500 mJ/cm ² x 2 strokes) to irradiate with ultraviolet rays to form an adhesive layer (primary hardening), and obtain a substrate-free double-sided adhesive sheet with an adhesive layer thickness of 100 μm. Then, peel off the release sheet on one side from the adhesive layer of the obtained substrate-free double-sided adhesive sheet, and press the exposed adhesive layer side to the easy-to-adhesive polyethylene terephthalate (PET) Sheet (thickness: 125 μm), a PET sheet with an adhesive layer having a thickness of 100 μm was obtained.

<Examples A2-A6, Comparative Examples A1, A2> The acrylic resin (A) and the photoinitiator (B) were changed as shown in Table 2, and each example was prepared in the same manner as in Example A1 except that Adhesive composition. Then, in the same manner as in Example A1, a substrate-free double-sided adhesive sheet with a thickness of 100 μm and a PET sheet with an adhesive layer were produced sequentially. Table 2 shows the composition of the adhesive composition of each example.

[Table 2] Acrylic resin (A) Photoinitiator (B) (parts) Cross-linking agent (C) (parts) Silane coupling agent (D) (parts) Intramolecular hydrogen abstraction photoinitiator (b1) Intermolecular hydrogen abstraction photoinitiator (b2) type Content (parts) Omnirad 754 TZT MBP Example A1 (A-A1) 100 2 1 - 5 0.1 Example A2 (A-A2) 100 2 1 - 5 0.1 Example A3 (A-A3) 100 2 - 1 5 0.1 Example A4 (A-A4) 100 2 - 1 5 0.1 Example A5 (A-A5) 100 2 - 1 5 0.1 Example A6 (A-A6) 100 2 - 1 5 0.1 Comparative Example A1 (A'-A1) 100 2 1 - 5 0.1 Comparative Example A2 (A'-A2) 100 2 - 1 5 0.1

<Measurement methods and evaluation methods> The measurement methods and evaluation methods of the adhesive compositions of Examples A1 to A6 and Comparative Examples A1 and A2 are shown below. The results are shown in Tables 3-5.

(Gel fraction: before complete hardening (after primary hardening)) After cutting the non-substrate double-sided adhesive sheet of each example into 40 mm×40 mm, let it stand for 30 minutes under the condition of 23°C×50%RH Afterwards, one of the release sheets was peeled off, and the exposed adhesive layer was attached to a 50 mm×100 mm SUS mesh (200 mesh). Peel off the rest of the release sheet, fold back from the center relative to the length direction of the SUS mesh, and wrap the adhesive layer with the SUS mesh. It was immersed in a sealed container containing 250 g of toluene maintained at 23°C for 24 hours, and the gel fraction (%) was calculated from the weight change at this time.

(Constant load holding power (50°C): before complete hardening (after primary hardening)) For the PET sheet with adhesive layer in each example, cut to a width of 25 mm x length of 75 mm (the width of the adhesive layer is 25 mm) × length 50 mm + width of non-adhesive layer part 25 mm × length 25 mm), peel off the release sheet. Press back and forth with a 2 kg roller to attach the exposed adhesive layer side to a stainless steel plate (SUS304) (attachment area 25 mm×50 mm), and let stand at 50°C for 20 minutes. Then, hang a weight of 50 g on the end of the length direction of the non-attached part (area 25 mm × 25 mm), and apply a load of 50 g along the direction of 90° to the plane of the stainless steel plate. After standing for 60 minutes, measure the peeling distance of the PET sheet. The evaluation criteria are as follows. A・・・The peeling distance is less than 10 mm. B・・・The peeling distance is more than 10 mm and less than 50 mm. C・・・The PET sheet was completely peeled off and fell off.

(Probe touch tack: before complete hardening (after first hardening)) For the PET sheet with the adhesive layer in each example, cut it into a size of 12 mm in width x 12 mm in length, peel off the release sheet, and use a probe Needle contact tack tester (manufactured by TESTER SANGYO company, probe contact tack tester TE-6001), pressurization time 1 second, attaching pressure 500 gf, pressing speed 120 mm/min, pulling speed 600 mm /min and the probe diameter is 5.1 mm (diameter) to measure the contact viscosity of the probe (unit: N). The evaluation criteria are as follows. A・・・Probe touch tack (unit: N) is less than 5. B・・・Probe tackiness (unit: N) is 5 or more and less than 7.5. C・・・Probe touch tack (unit: N) is 7.5 or more and less than 10. D・・・Probe touch tack (unit: N) is 10 or more.

(Gel fraction: after complete hardening) For each double-sided adhesive sheet without substrate, the peak illuminance: 150 mW/cm ² , cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² ×4 strokes) after ultraviolet irradiation, cut into 40 mm × 40 mm, and let it stand for 30 minutes under the condition of 23°C × 50%RH. Thereafter, one of the release sheets was peeled off, and the exposed adhesive layer was attached to a 50 mm×100 mm SUS mesh (200 mesh). Peel off the rest of the release sheet, fold back from the center relative to the length direction of the SUS mesh, and wrap the adhesive layer with the SUS mesh. It was immersed in a sealed container containing 250 g of toluene maintained at 23°C for 24 hours, and the gel fraction (%) was calculated from the weight change at this time.

(180-degree peel strength (23°C): after complete hardening) For the PET sheet with the adhesive layer in each case, cut it into a size of 25 mm in width x 100 mm in length, and use a high-pressure mercury UV irradiation device to measure the peak illuminance: 150 mW/cm ² , cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² ×4 strokes) after ultraviolet irradiation, the release sheet was peeled off. In an environment of 23°C and 50%RH, use a 2 kg rubber roller to reciprocate twice to apply pressure to attach the exposed adhesive layer side to an alkali-free glass ("Eagle XG" manufactured by Corning, thickness 1.1 mm), and Leave to stand for 30 minutes under the same conditions. Thereafter, the 180-degree peel strength (N/25 mm) was measured at normal temperature (23° C.) at a peel speed of 300 mm/min.

(Constant load retention (80°C): after complete hardening) For the PET sheet with the adhesive layer in each case, it was cut to a width of 25 mm × length 75 mm (width of the adhesive layer part 25 mm × length 50 mm + non- The width of the adhesive layer is 25 mm x length 25 mm), and the peak illuminance: 150 mW/cm ² , cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² x 4 strokes) using a high-pressure mercury UV irradiation device After irradiating with ultraviolet light under the same conditions, peel off the release sheet. Press back and forth with a 2 kg roller to attach the exposed adhesive layer side to a stainless steel plate (SUS304) (attachment area 25 mm×50 mm), and let stand at 80°C for 20 minutes. Then, hang a weight of 50 g on the end of the length direction of the non-attached part (area 25 mm × 25 mm), and apply a load of 50 g along the direction of 90° relative to the plane of the stainless steel plate. Let it stand for 60 minutes, and measure the peeling distance of the PET sheet. The evaluation criteria are as follows. A・・・The peeling distance is less than 5 mm. B・・・The peeling distance is more than 5 mm and less than 10 mm. C・・・The peeling distance is 10 mm or more, or the PET sheet is completely peeled off and falls off.

(Retention force (80°C): after complete hardening) For the PET sheet with adhesive layer in each case, cut it into a size of 25 mm×50 mm, use a high-pressure mercury UV irradiation device to measure the peak illuminance: 150 mW/cm ² , Cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² × 4 strokes) after ultraviolet irradiation, peel off the release sheet. Put the stainless steel plate (SUS304) on the side of the exposed adhesive layer, press it back and forth with a 2 kg roller to attach it (attachment area 25 mm × 25 mm), use a creep tester (manufactured by TESTER SANGYO company, attached Constant Humidity Chamber Retention Tester BE-501), apply a load of 1 kg for 24 hours at 80°C to measure the retention. The evaluation criteria are as follows. A・・・No offset. B・・・The deviation is less than 1.0 mm. C・・・The deviation is more than 1.0 mm or the PET sheet falls off.

(Moisture and heat resistance test: after complete hardening) For the PET sheet with the adhesive layer in each example, cut it into a size of 30 mm × 50 mm, use a high-pressure mercury UV irradiation device with a peak illuminance: 150 mW/cm ² , cumulative Exposure amount: 4000 mJ/cm ² (1000 mJ/cm ² x 4 strokes) After ultraviolet irradiation, the release sheet was peeled off. The side of the exposed adhesive layer was bonded to an alkali-free glass ("Eagle XG" manufactured by Corning, thickness 1.1 mm). Afterwards, autoclave treatment at 50°C, 0.5 MPa, and 20 minutes, and let stand at 23°C, 50%RH for 30 minutes to produce a layer with "alkali-free glass/adhesive layer/PET" Composed of test pieces. Using the obtained test piece, conduct a heat and humidity resistance test for 7 days (168 hours) in an environment of 60°C and 90% RH, and measure the haze value before and after the heat and humidity resistance test.

The haze value is measured by using HAZE MATER NDH4000 (manufactured by Nippon Denshoku Industries Co., Ltd.) to measure the diffuse transmittance and total light transmittance, and substitute the obtained values of diffuse transmittance (DT) and total light transmittance (TT) into the following [Formula 1] and calculated. Furthermore, the rate of increase (%) of the haze value was calculated from the following [Formula 2]. This machine complies with JIS K7361-1. Haze value (%) = (DT/TT) × 100 ・・・[Formula 1] Haze value difference (%) = Haze value after the heat and humidity resistance test - Haze value before the heat and humidity resistance test started・・・[Formula 2]

The evaluation criteria of the heat and humidity resistance test are as follows. A・・・The difference in haze value is less than 0.5%. B・・・The difference in haze value is 0.5% or more and less than 3.0%. C・・・The difference in haze value is 3.0% or more.

(Probe touch tack: after complete hardening) For the PET sheet with the adhesive layer in each case, cut it into a size of 12 mm in width x 12 mm in length, and use a high-pressure mercury UV irradiation device to measure the peak illuminance: 150 mW/cm ^2. Cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² × 4 strokes) after ultraviolet irradiation, peel off the release sheet, and use a probe contact adhesion tester (manufactured by TESTER SANGYO company, probe touch Viscosity tester TE-6001), measured under the conditions of pressurization time 5 seconds, attachment pressure 1000 gf, pressing speed 120 mm/min, pulling speed 600 mm/min, probe diameter 5.1 mm (diameter) Probe contact viscosity (unit: N). The evaluation criteria are as follows. A・・・Probe tackiness (unit: N) is less than 5. B・・・Probe touch tack (unit: N) is 5 or more and less than 7.5. C・・・Probe touch tack (unit: N) is 7.5 or more and less than 10. D・・・Probe tackiness (unit: N) is 10 or more.

之方式彎曲，以該狀態加以固定後，進行高壓釜處理(0.5 MPa×50℃×20分鐘)，利用高壓水銀UV照射裝置以峰照度：150 mW/cm ²、累計曝光量：4000 mJ/cm ²(1000 mJ/cm ²×4行程)對彎曲之狀態之樣品進行紫外線照射，而製作曲面耐久評價用樣品。曲面耐久評價用樣品具有自外側起依序為PET/黏著層/偏光板/鋁板之層構成。最內側有鋁板。  使用所獲得之曲面耐久評價用樣品，於80℃、乾燥、7天之條件下及60℃、90%RH、7天之條件下分別暴露後，觀察彎曲部及除彎曲部以外之偏光板端部，按照以下基準進行評價。 (Curved surface durability: after complete hardening) For the PET sheet with the adhesive layer in each example, cut it into a size of 40 mm×120 mm, and peel off the release sheet. The side of the exposed adhesive layer is pressure-bonded to one of the polarizing plates with TAC (triacetyl cellulose, triacetyl cellulose) film on the double-layered polarizing plate of the polarizing element to obtain a "PET sheet/ Adhesive layer/polarizer" layer composed of laminated body. Afterwards, the laminate was attached and fixed to an aluminum plate (width 70 mm, length 150 mm, thickness 0.3 mm) with adhesive tape in such a way that the PET surface became the surface, and an aluminum plate fixed sample was produced. Use the mandrel testing machine to make the sample to be 5 mm

After being bent in the same way and fixed in this state, autoclave treatment (0.5 MPa×50℃×20 minutes) was performed, and the peak illuminance: 150 mW/cm ² and cumulative exposure: 4000 mJ/cm were used by a high-pressure mercury UV irradiation device. ² (1000 mJ/cm ² ×4 strokes) irradiate the bent sample with ultraviolet light to make a curved surface durability evaluation sample. The sample for curved surface durability evaluation has a layer configuration of PET/adhesive layer/polarizing plate/aluminum plate in order from the outside. There is an aluminum plate on the innermost side. Using the obtained sample for curved surface durability evaluation, after exposing to the conditions of 80°C, dry, 7 days and 60°C, 90%RH, 7 days, respectively, observe the bent part and the polarizer end except the bent part Departments are evaluated according to the following criteria.

(Evaluation criteria: curved portion) A・・・Swelling, foaming, and paste overflow were not observed. B・・・Swelling, foaming, or overflow of paste is observed.

(Evaluation criteria: Polarizing plate edge) A... Neither swelling nor air bubbles were observed at the edge. B・・・Very few air bubbles were observed at the end. C・・・Bubbles were observed at one part of the end. D・・・Swelling and air bubbles are generated on the whole end.

(Evaluation criteria: comprehensive evaluation) A・・・The evaluation of the curved part is A and the evaluation of the edge of the polarizing plate is A. B・・・The evaluation of the curved part is A and the evaluation of the edge of the polarizer is B or C. C・・・The evaluation of the curved part is A and the evaluation of the edge of the polarizer is D. D・・・The evaluation of the curved part is B and the evaluation of the edge of the polarizing plate is any one of A to D.

(Durability of polarizing plate: after complete hardening) For each case, the double-sided adhesive sheet without substrate was cut to a size of 60 mm×100 mm, and one of the release sheets was peeled off. The side of the exposed adhesive layer is pressure-bonded to the TAC-based film surface polarizing plate of the double-layered polarizing plate with TAC-based film of the polarizing element. Next, the other release sheet was peeled off, and the exposed adhesive layer was bonded to an alkali-free glass ("Eagle XG" manufactured by Corning, thickness 1.1 mm), and autoclaved (50°C, 0.5 MPa, 20 minutes ). Afterwards, using a high-pressure mercury UV irradiation device to irradiate ultraviolet rays from the alkali-free glass side with peak illuminance: 150 mW/cm ² , cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² × 4 strokes), and produce polarized light Samples for board durability evaluation. After the samples for durability evaluation of polarizing plates were left to stand at 23°C and 50%RH for 1 day, the durability test was carried out at 80°C and 60°C and 90%RH for 7 days (168 hours) respectively. , and evaluated according to the following criteria. A・・・The bulge at the end of the polarizer does not reach 1 mm. B・・・The bulge at the end of the polarizer is 1 mm or more and less than 2 mm. C・・・The bulge at the end of the polarizer is 2 mm or more.

[table 3] Adhesive properties before complete hardening (after first hardening) Adhesive properties after complete hardening Gel fraction (%) Constant load retention (50℃) Probe Tackiness Gel fraction (%) 180 degree peel strength (23℃) Constant load retention (80℃) Holding power 80℃ Peeling distance evaluate (N) evaluate (N/25mm) Peeling distance evaluate offset evaluate Example A1 0.8 13 mm B 3.9 A 51.3 25.5 4 mm A 0.75 mm B Example A2 10.6 8 mm A 4.6 A 59.2 23.6 4 mm A no offset A Example A3 10.0 2 mm A 6.7 B 64.4 31.2 1 mm A no offset A Example A4 1.0 30 mm B 6.7 B 57.7 29.6 1 mm A no offset A Example A5 0.6 45 mm B 4.4 A 55.6 32.2 2 mm A no offset A Example A6 0.9 25 mm B 4.0 A 50.5 34.3 1 mm A no offset A Comparative Example A1 0.5 drop C 13.9 D. 49.9 29.5 15 mm C 0.6 mm B Comparative Example A2 20.4 drop C 12.6 D. 61.1 27.2 drop C no offset A

[Table 4] Adhesive properties after complete hardening Humidity and heat resistance test Probe Tackiness Haze value before test (%) Haze value after test (%) Haze value difference (%) evaluate (N) evaluate Example A1 0.5 0.6 0.1 A 4.7 A Example A2 0.5 0.7 0.2 A 4.8 A Example A3 0.6 0.8 0.3 A 6.3 B Example A4 0.5 0.9 0.3 A 5.3 B Example A5 0.5 0.7 0.2 A 5.6 B Example A6 0.5 0.7 0.2 A 3.5 A Comparative Example A1 0.6 0.8 0.3 A 17.8 D. Comparative Example A2 0.5 0.8 0.3 A 15.0 D.

[table 5] Reliability after full hardening Curved Surface Durability 80°C Curved Surface Durability 60℃/90%RH Polarizer durability 80°C, dry Polarizer Durability 60℃/90%RH curved part Ends Overview curved part Ends Overview end bulge evaluate end bulge evaluate Example A1 A C B A C B less than 1 mm A less than 1 mm A Example A2 A B B A B B less than 1 mm A less than 1 mm A Example A3 A A A A A A less than 1 mm A less than 1 mm A Example A4 A A A A A A less than 1 mm A More than 1 mm and less than 2 mm B Example A5 A A A A A A less than 1 mm A less than 1 mm A Example A6 A A A A A A less than 1 mm A less than 1 mm A Comparative Example A1 B D. D. B D. D. 10 mm or more C 10 mm or more C Comparative Example A2 A A A A A A less than 1 mm A less than 1 mm A

Adhesive sheets made using the adhesive compositions of Examples A1-A6 also exhibited low contact tack and high constant load retention in a low-crosslinked state before complete hardening (after primary hardening). Adhesive properties. Also, it exhibits excellent adhesive properties and durability even after it is fully cured. On the other hand, in Comparative Examples A1 and A2, the glass transition temperature of the acrylic resin (A) did not reach -10°C. In Comparative Example A1, the alkyl methacrylate (a2) was not included, and the total content of the alkyl acrylate (a1) and the alkyl methacrylate (a2) was less than 30% by weight. In Comparative Example A2, the weight ratio of the alkyl acrylate (a1) to the alkyl methacrylate (a2) was 85.7/14.3. In these Comparative Examples A1 and A2, compared with Examples A1-A6, the adhesive properties in the low cross-linked state after primary curing, the adhesive properties or reliability after complete curing are also inferior.

[Example and Comparative Example of the Second Aspect] Hereinafter, although the Example and the comparative example which are the 2nd aspect of this invention are demonstrated concretely, this invention is not limited to the following description. In the example, "part" and "%" mean a weight basis. Also, the weight average molecular weight of the acrylic resin (A), the measurement of the glass transition temperature based on dynamic viscoelasticity, the thickness of the adhesive layer, and the haze value (%) are described in accordance with the embodiment of the second aspect above. method to measure.

＜Abbreviation, raw material＞ (Alkyl (meth)acrylate (a1)) ・EMA: Ethyl methacrylate (Tg of homopolymer: 65℃) ・MA: Methyl acrylate (Tg of homopolymer: 8 ℃) ・MMA: methyl methacrylate (Tg of homopolymer: 105℃)

(Hydroxyalkyl Monomer (a2)) ・4HBA: 4-Hydroxybutyl Acrylate ・HEA: 2-Hydroxyethyl Acrylate

(Ethylenically unsaturated monomer (a3)) ・2EHA: 2-ethylhexyl acrylate (Tg of homopolymer: -70°C)

・ADVN: 2,2'-azobis(2,4-dimethylvaleronitrile) (10-hour half-life temperature 52°C)

(Photoinitiator (B)) [Intramolecular hydrogen abstraction type photoinitiator (b1)] ・Omnirad 754: a product manufactured by IGM Resins B.V. [Intermolecular hydrogen abstraction type photoinitiator (b2)] ・Omnipol BP: Products manufactured by IGM Resins B.V. ・Esacure TZT: Products manufactured by IGM Resins B.V. ・MBP: Products manufactured by Xinling Corporation

(Crosslinking agent (C)) ・Polypropylene glycol #400 diacrylate (NK ester APG400, manufactured by Shin-Nakamura Chemical Co., Ltd.)

(Silane coupling agent (D)) ・KBM403 (manufactured by Shin-Etsu Chemical Co., Ltd.)

<Production Example B1: Production of Acrylic Resin (A-B1)> EMA: 35 parts, MA: 10 parts, 4HBA: 5 parts, HEA: 10 parts, 2EHA: 40 parts were mixed to prepare a monomer solution. Into a 2 L flask with a cooler, put ethyl acetate as a polymerization solvent: 18 parts (boiling point 77°C), methyl ethyl ketone: 18 parts (boiling point 80°C), ADVN as a polymerization initiator: 0.01 Parts, 10% of 100 parts of the pre-mixed monomer solution, after heating to reflux in the flask, add ethyl acetate: 10 parts, ADVN: 0.18 parts, and the remaining 90 parts of the above-mentioned monomer solution %. Furthermore, after dripping for 30 minutes, the mixture of ethyl acetate: 10 parts and ADVN: 0.13 parts was dripped and reacted over 1 hour, and the solution of the acrylic resin (A-B1) was obtained. Table 6 shows the measurement results of the weight average molecular weight (Mw), degree of dispersion, and glass transition temperature based on dynamic viscoelasticity of the acrylic resin (A-B1).

<Production Examples B2-B4, Comparative Production Examples B1-B4> The composition of the copolymerization component including the monomer solution was set as shown in Table 6, and the acrylic resin (A -B2) to acrylic resin (A-B4), acrylic resin (A'-B1) to acrylic resin (A'-B4). Table 6 shows the measurement results of the weight average molecular weight (Mw), degree of dispersion, and glass transition temperature based on dynamic viscoelasticity of each acrylic resin.

[Table 6] acrylic resin Copolymer composition (parts) The average carbon number of the alkyl group of the hydroxyalkyl monomer (a2) Mw (×10 ⁴ ) Dispersion Glass transition temperature (°C) EMA (a1) (Tg: 65°C) MA (a1) (Tg: 8°C) MMA (a1) (Tg: 105°C) 4HBA (a2) HEA (a2) 2EHA (a3) (A-B1) 35 10 - 5 10 40 2.7 twenty one 2.57 4 (A-B2) 35 10 - 7.5 7.5 40 3.0 17 2.50 4 (A-B3) 35 10 - 15 - 40 4.0 twenty one 2.84 4 (A-B4) - 15 30 15 - 40 4.0 twenty four 3.03 12 (A'-B1) - 25 - - 15 60 2.0 12 2.59 -15 (A'-B2) 40 - - - 15 45 2.0 15 2.29 9 (A'-B3) twenty three 7 - - 10 60 2.0 18 2.54 -13

<Example B1> With respect to 100 parts of acrylic resin (A-B1) solution (solid content conversion), Omnirad 754: 2.0 parts (solid content conversion), MBP: 1.0 parts (solid content conversion), Polypropylene glycol #400 diacrylate: 5.0 parts (solid content conversion), KBM403: 0.1 part (solid content conversion) were mixed, and the adhesive composition was obtained. Adjust the obtained adhesive composition with ethyl acetate to a solid content concentration of 45%, apply it on a polyester release sheet so that the thickness after drying becomes about 50 μm, and dry it at 100°C for 5 minutes. An adhesive composition layer is formed.

Prepare two polyester-based release sheets on which the adhesive composition layer was formed as described above, and laminate the two adhesive composition layers facing each other. In the state where both sides of the laminated adhesive composition layer are sandwiched by polyester release sheets, the peak illuminance: 150 mW/cm ² and the cumulative exposure amount: 1000 mJ/cm are used by a high-pressure mercury UV irradiation device. ² (500 mJ/cm ² x 2 strokes) to irradiate with ultraviolet rays to form an adhesive layer (primary hardening), and obtain a substrate-free double-sided adhesive sheet with an adhesive layer thickness of 100 μm. Then, peel off the release sheet on one side from the adhesive layer of the obtained substrate-free double-sided adhesive sheet, and press the exposed adhesive layer side to the easy-to-adhesive polyethylene terephthalate (PET) Sheet (thickness: 125 μm), a PET sheet with an adhesive layer having a thickness of 100 μm was obtained.

<Examples B2-B5, Comparative Examples B1-B4> As shown in Table 7, except that the acrylic resin (A) and the photoinitiator (B) were changed, each was prepared in the same manner as in Example B1. An example of an adhesive composition. Then, in the same manner as in Example B1, a substrate-free double-sided adhesive sheet with a thickness of 100 μm and a PET sheet with an adhesive layer were produced sequentially. Table 7 shows the composition of the adhesive composition of each example.

[Table 7] Acrylic resin (A) Photoinitiator (B) (parts) Cross-linking agent (C) (parts) Silane coupling agent (D) (parts) Intramolecular hydrogen abstraction photoinitiator (b1) Intermolecular hydrogen abstraction photoinitiator (b2) type Content (parts) Omnirad 754 TZT MBP Omnipol BP Example B1 (A-B1) 100 2 - 1 - 5 0.1 Example B2 (A-B2) 100 2 - 1 - 5 0.1 Example B3 (A-B2) 100 2 - - 1 5 0.1 Example B4 (A-B3) 100 2 1 - - 5 0.1 Example B5 (A-B4) 100 2 1 - - 5 0.1 Comparative Example B1 (A'-B1) 100 2 1 - - 5 0.1 Comparative Example B2 (A'-B2) 100 2 1 - - 5 0.1 Comparative Example B3 (A-B2) 100 - 3 - - 5 0.1 Comparative Example B4 (A'-B3) 100 2 - 1 - 5 0.1

<Measurement methods and evaluation methods> The measurement methods and evaluation methods of the adhesive compositions of Examples B1 to B5 and Comparative Examples B1 to B4 are shown below. The results are shown in Tables 8-10.

(Gel fraction: before complete hardening (after primary hardening)) After cutting the non-substrate double-sided adhesive sheet of each example into 40 mm×40 mm, let it stand for 30 minutes under the condition of 23°C×50%RH Afterwards, one of the release sheets was peeled off, and the exposed adhesive layer was attached to a 50 mm×100 mm SUS mesh (200 mesh). Peel off the rest of the release sheet, fold back from the center relative to the length direction of the SUS mesh, and wrap the adhesive layer with the SUS mesh. It was immersed in a sealed container containing 250 g of toluene maintained at 23°C for 24 hours, and the gel fraction (%) was calculated from the weight change at this time.

(Constant load holding power (50°C): before complete hardening (after primary hardening)) For the PET sheet with adhesive layer in each example, cut to a width of 25 mm x length of 75 mm (the width of the adhesive layer is 25 mm) × length 50 mm + width of non-adhesive layer part 25 mm × length 25 mm), peel off the release sheet. Press back and forth with a 2 kg roller to attach the exposed adhesive layer side to a stainless steel plate (SUS304) (attachment area 25 mm×50 mm), and let stand at 50°C for 20 minutes. Then, hang a weight of 50 g on the end of the length direction of the non-attached part (area 25 mm × 25 mm), and apply a load of 50 g along the direction of 90° relative to the plane of the stainless steel plate. Let it stand for 60 minutes, and measure the peeling distance of the PET sheet. The evaluation criteria are as follows. A・・・The peeling distance is less than 10 mm. B・・・The peeling distance is more than 10 mm and less than 50 mm. C・・・The PET sheet was completely peeled off and fell off.

(Probe touch tack: before complete hardening (after first hardening)) For the PET sheet with the adhesive layer in each example, cut it into a size of 12 mm in width x 12 mm in length, peel off the release sheet, and use a probe Needle contact tack tester (manufactured by TESTER SANGYO company, probe contact tack tester TE-6001), pressurization time 1 second, attaching pressure 500 gf, pressing speed 120 mm/min, pulling speed 600 mm /min and the probe diameter is 5.1 mm (diameter) to measure the contact viscosity of the probe (unit: N). The evaluation criteria are as follows. A・・・Probe touch tack (unit: N) is less than 5. B・・・Probe tackiness (unit: N) is 5 or more and less than 7.5. C・・・Probe touch tack (unit: N) is 7.5 or more and less than 10. D・・・Probe touch tack (unit: N) is 10 or more.

(Gel fraction: after complete hardening) For each double-sided adhesive sheet without substrate, the peak illuminance: 150 mW/cm ² , cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² ×4 strokes) after ultraviolet irradiation, cut into 40 mm × 40 mm, and let it stand for 30 minutes under the condition of 23°C × 50%RH. Thereafter, one of the release sheets was peeled off, and the exposed adhesive layer was attached to a 50 mm×100 mm SUS mesh (200 mesh). Peel off the rest of the release sheet, fold back from the center relative to the length direction of the SUS mesh, and wrap the adhesive layer with the SUS mesh. It was immersed in a sealed container containing 250 g of toluene maintained at 23°C for 24 hours, and the gel fraction (%) was calculated from the weight change at this time.

(180-degree peel strength (23°C): after complete hardening) For the PET sheet with the adhesive layer in each case, cut it into a size of 25 mm in width x 100 mm in length, and use a high-pressure mercury UV irradiation device to measure the peak illuminance: 150 mW/cm ² , cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² ×4 strokes) after ultraviolet irradiation, the release sheet was peeled off. In an environment of 23°C and 50%RH, use a 2 kg rubber roller to reciprocate twice to apply pressure to attach the exposed adhesive layer side to an alkali-free glass ("Eagle XG" manufactured by Corning, thickness 1.1 mm), and Leave to stand for 30 minutes under the same conditions. Thereafter, the 180-degree peel strength (N/25 mm) was measured at normal temperature (23° C.) at a peel speed of 300 mm/min.

(Constant load retention (80°C): after complete hardening) For the PET sheet with the adhesive layer in each case, it was cut to a width of 25 mm × length 75 mm (width of the adhesive layer part 25 mm × length 50 mm + non- The width of the adhesive layer is 25 mm x length 25 mm), and the peak illuminance: 150 mW/cm ² , cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² x 4 strokes) using a high-pressure mercury UV irradiation device After irradiating with ultraviolet light under the same conditions, peel off the release sheet. Press back and forth with a 2 kg roller to attach the exposed adhesive layer side to a stainless steel plate (SUS304) (attachment area 25 mm×50 mm), and let stand at 80°C for 20 minutes. Then, hang a weight of 50 g on the end of the length direction of the non-attached part (area 25 mm × 25 mm), and apply a load of 50 g along the direction of 90° relative to the plane of the stainless steel plate. Let it stand for 60 minutes, and measure the peeling distance of the PET sheet. The evaluation criteria are as follows. A・・・The peeling distance is less than 5 mm. B・・・The peeling distance is more than 5 mm and less than 10 mm. C・・・The peeling distance is 10 mm or more, or the PET sheet is completely peeled off and falls off.

(Retention force (80°C): after complete hardening) For the PET sheet with adhesive layer in each case, cut it into a size of 25 mm×50 mm, use a high-pressure mercury UV irradiation device to measure the peak illuminance: 150 mW/cm ² , Cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² × 4 strokes) after ultraviolet irradiation, peel off the release sheet. Put the stainless steel plate (SUS304) on the side of the exposed adhesive layer, press it back and forth with a 2 kg roller to attach it (attachment area 25 mm × 25 mm), use a creep tester (manufactured by TESTER SANGYO company, attached Constant Humidity Chamber Retention Tester BE-501), apply a load of 1 kg for 24 hours at 80°C to measure the retention. The evaluation criteria are as follows. A・・・No offset. B・・・The deviation is less than 1.0 mm. C・・・The deviation is more than 1.0 mm or the PET sheet falls off.

(Moisture and heat resistance test: after complete hardening) For the PET sheet with the adhesive layer in each example, cut it into a size of 30 mm × 50 mm, use a high-pressure mercury UV irradiation device with a peak illuminance: 150 mW/cm ² , cumulative Exposure amount: 4000 mJ/cm ² (1000 mJ/cm ² x 4 strokes) After ultraviolet irradiation, the release sheet was peeled off. The side of the exposed adhesive layer was bonded to an alkali-free glass ("Eagle XG" manufactured by Corning, thickness 1.1 mm). Afterwards, autoclave treatment at 50°C, 0.5 MPa, and 20 minutes, and let stand at 23°C, 50%RH for 30 minutes to produce a layer with "alkali-free glass/adhesive layer/PET" Composed of test pieces. Using the obtained test piece, conduct a heat and humidity resistance test for 7 days (168 hours) in an environment of 60°C and 90% RH, and measure the haze value before and after the heat and humidity resistance test.

The haze value is measured by using HAZE MATER NDH4000 (manufactured by Nippon Denshoku Industries Co., Ltd.) to measure the diffuse transmittance and total light transmittance, and substitute the obtained values of diffuse transmittance (DT) and total light transmittance (TT) into the following [Formula 1] and calculated. Furthermore, the rate of increase (%) of the haze value was calculated from the following [Formula 2]. This machine complies with JIS K7361-1. Haze value (%) = (DT/TT) × 100 ・・・[Formula 1] Haze value difference (%) = Haze value after the heat and humidity resistance test - Haze value before the heat and humidity resistance test started・・・[Formula 2]

The evaluation criteria of the heat and humidity resistance test are as follows. A・・・The difference in haze value is less than 0.5%. B・・・The difference in haze value is 0.5% or more and less than 3.0%. C・・・The difference in haze value is 3.0% or more.

(Probe touch tack: after complete hardening) For the PET sheet with the adhesive layer in each case, cut it into a size of 12 mm in width x 12 mm in length, and use a high-pressure mercury UV irradiation device to measure the peak illuminance: 150 mW/cm ^2. Cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² × 4 strokes) after ultraviolet irradiation, peel off the release sheet, and use a probe contact adhesion tester (manufactured by TESTER SANGYO company, probe touch Viscosity tester TE-6001), with a pressurization time of 5 seconds, a sticking pressure of 1000 gf/cm ² , a pressing speed of 120 mm/min, a pulling speed of 600 mm/min, and a probe diameter of 5.1 mm (diameter) The contact viscosity of the probe (unit: N) was measured under the same conditions. The evaluation criteria are as follows. A・・・Probe tackiness (unit: N) is less than 5. B・・・Probe touch tack (unit: N) is 5 or more and less than 7.5. C・・・Probe touch tack (unit: N) is 7.5 or more and less than 10. D・・・Probe tackiness (unit: N) is 10 or more.

之方式彎曲，以該狀態加以固定後，進行高壓釜處理(0.5 MPa×50℃×20分鐘)，利用高壓水銀UV照射裝置以峰照度：150 mW/cm ²、累計曝光量：4000 mJ/cm ²(1000 mJ/cm ²×4行程)對彎曲之狀態之樣品進行紫外線照射，而製作曲面耐久評價用樣品。曲面耐久評價用樣品具有自外側起依序為PET/黏著層/偏光板/鋁板之層構成。最內側有鋁板。  使用所獲得之曲面耐久評價用樣品，於80℃、乾燥、7天之條件下及60℃、90%RH、7天之條件下分別暴露後，觀察彎曲部及除彎曲部以外之偏光板端部，按照以下基準進行評價。 (Curved surface durability: after complete hardening) For the PET sheet with the adhesive layer in each example, cut it into a size of 40 mm×120 mm, and peel off the release sheet. The side of the exposed adhesive layer is pressure-bonded to the TAC-based film surface polarizing plate, one of the double-layered polarizing plates with TAC-based film on the polarizing element, to obtain a layer composition of "PET sheet/adhesive layer/polarizing plate" The laminate. Afterwards, the laminate was attached and fixed to an aluminum plate (width 70 mm, length 150 mm, thickness 0.3 mm) with adhesive tape in such a way that the PET surface became the surface, and an aluminum plate fixed sample was produced. Use the mandrel testing machine to make the sample to be 5 mm

After being bent in the same way and fixed in this state, autoclave treatment (0.5 MPa×50℃×20 minutes) was performed, and the peak illuminance: 150 mW/cm ² and cumulative exposure: 4000 mJ/cm were used by a high-pressure mercury UV irradiation device. ² (1000 mJ/cm ² ×4 strokes) irradiate the bent sample with ultraviolet light to make a curved surface durability evaluation sample. The sample for curved surface durability evaluation has a layer configuration of PET/adhesive layer/polarizing plate/aluminum plate in order from the outside. There is an aluminum plate on the innermost side. Using the obtained sample for curved surface durability evaluation, after exposing to the conditions of 80°C, dry, 7 days and 60°C, 90%RH, 7 days, respectively, observe the bent part and the polarizer end except the bent part Departments are evaluated according to the following criteria.

(Evaluation criteria: curved portion) A・・・Swelling, foaming, and paste overflow were not observed. B・・・Swelling, foaming, or overflow of paste is observed.

(Evaluation criteria: Polarizing plate edge) A... Neither swelling nor air bubbles were observed at the edge. B・・・Very few air bubbles were observed at the end. C・・・Bubbles were observed at one part of the end. D・・・Swelling and air bubbles are generated on the whole end.

(Evaluation criteria: comprehensive evaluation) A・・・The evaluation of the curved part is A and the evaluation of the edge of the polarizing plate is A. B・・・The evaluation of the curved part is A and the evaluation of the edge of the polarizer is B or C. C・・・The evaluation of the curved part is A and the evaluation of the edge of the polarizer is D. D・・・The evaluation of the curved part is B and the evaluation of the edge of the polarizing plate is any one of A to D.

(Durability of polarizing plate: after complete hardening) For each case, the double-sided adhesive sheet without substrate was cut to a size of 60 mm×100 mm, and one of the release sheets was peeled off. The side of the exposed adhesive layer is pressure-bonded to the TAC-based film surface polarizing plate of the double-layered polarizing plate with TAC-based film of the polarizing element. Next, the other release sheet was peeled off, and the exposed adhesive layer was bonded to an alkali-free glass ("Eagle XG" manufactured by Corning, thickness 1.1 mm), and autoclaved (50°C, 0.5 MPa, 20 minutes ). Afterwards, using a high-pressure mercury UV irradiation device to irradiate ultraviolet rays from the alkali-free glass side with peak illuminance: 150 mW/cm ² , cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² × 4 strokes), and produce polarized light Samples for board durability evaluation. After the samples for durability evaluation of polarizing plates were left to stand at 23°C and 50%RH for 1 day, the durability test was carried out at 80°C and 60°C and 90%RH for 7 days (168 hours) respectively. , and evaluated according to the following criteria. A・・・The bulge at the end of the polarizer does not reach 1 mm. B・・・The bulge at the end of the polarizer is 1 mm or more and less than 2 mm. C・・・The bulge at the end of the polarizer is 2 mm or more.

[Table 8] Adhesive properties before complete hardening (after first hardening) Adhesive properties after complete hardening Gel fraction (%) Constant load retention (50℃) Probe Tackiness Gel fraction (%) 180 degree peel strength (23℃) Constant load retention (80℃) Holding power 80℃ Peeling distance evaluate (N) evaluate (N/25mm) Peeling distance evaluate offset evaluate Example B1 0.6 11 mm B 4.6 A 59.0 25.2 3 mm A no offset A Example B2 1.1 45 mm B 7.1 B 52.8 23.1 4 mm A no offset A Example B3 1.2 45 mm B 5.5 B 56.3 27.0 3 mm A 0.45 mm B Example B4 7.4 10 mm B 5.4 B 61.1 26.2 4 mm A no offset A Example B5 2.1 7 mm A 3.7 A 54.0 25.9 3 mm A no offset A Comparative Example B1 0.5 drop C 13.9 D. 49.9 29.5 15 mm C 0.6 mm B Comparative Example B2 0.8 drop C 3.4 A 36.8 26.0 6 mm B 1.5 mm C Comparative Example B3 0.9 drop C 4.2 A 48.1 29.1 6 mm B no offset A Comparative Example B4 1.1 drop C 10.9 D. 61.1 28.4 6 mm B no offset A

[Table 9] Adhesive properties after complete hardening Humidity and heat resistance test Probe Tackiness Haze value before test (%) Haze value after test (%) Haze value difference (%) evaluate (N) evaluate Example B1 0.5 0.7 0.2 A 4.1 A Example B2 0.4 2.6 2.2 B 5.1 B Example B3 0.5 3.0 2.6 B 5.5 B Example B4 0.5 0.5 0.1 A 5.4 B Example B5 0.4 0.6 0.1 A 3.4 A Comparative Example B1 0.6 0.8 0.3 A 17.8 D. Comparative Example B2 0.5 0.4 0.1 A 4.1 A Comparative Example B3 0.5 2.6 2.1 B 6.5 B Comparative Example B4 0.5 1.1 0.6 B 12.3 D.

[Table 10] Reliability after full hardening Curved surface durability 80°C, dry Curved Surface Durability 60℃/90%RH Polarizer durability 80°C, dry Polarizer Durability 60℃/90%RH curved part Ends Overview curved part Ends Overview end bulge evaluate end bulge evaluate Example B1 A B B A B B less than 1 mm A less than 1 mm A Example B2 A B B A C B less than 1 mm A less than 1 mm A Example B3 A B B A C B More than 1 mm and less than 2 mm B More than 1 mm and less than 2 mm B Example B4 A A A A A A less than 1 mm A less than 1 mm A Example B5 A C B A A A less than 1 mm A less than 1 mm A Comparative Example B1 B D. D. B D. D. 10 mm or more C 10 mm or more C Comparative Example B2 B D. D. B D. D. More than 1 mm and less than 2 mm B More than 2 mm and less than 10 mm C Comparative Example B3 B D. D. B D. D. More than 2 mm and less than 10 mm C More than 2 mm and less than 10 mm C Comparative Example B4 A A A B A D. More than 2 mm and less than 10 mm C More than 2 mm and less than 10 mm C

Adhesive sheets made using the adhesive compositions of Examples B1-B5 also exhibited low contact tack and high constant load retention in a low-crosslinked state before complete hardening (after primary hardening). Adhesive properties. Also, it exhibits excellent adhesive properties and durability even after it is fully cured. On the other hand, in Comparative Examples B1 and B4, the glass transition temperature of the acrylic resin (A) did not reach -10°C. In Comparative Examples B1, B2, and B4, the average carbon number of the alkyl chain of the hydroxyalkyl monomer (a2) in the copolymerization component (a) was less than 2.1. In Comparative Example B3, no intramolecular hydrogen abstraction photoinitiator was used. In these Comparative Examples B1-B4, compared with Examples B1-B5, the adhesive properties in the low-crosslinked state after primary curing are inferior, and the durability after complete curing is also inferior.

[Embodiment and Comparative Example of the Third Aspect] Examples and comparative examples of the third aspect of the present invention will be specifically described below, but the present invention is not limited to the following description. In the example, "part" and "%" mean a weight basis. Also, the weight average molecular weight of the acrylic resin (A), the measurement of the glass transition temperature based on dynamic viscoelasticity, the thickness of the adhesive layer, and the haze value (%) are described in accordance with the embodiment of the third aspect above. method to measure.

＜Abbreviation, raw material＞ (Acrylic resin (A)) [Branched alkyl (meth)acrylate (a1)] ・iBMA: Isobutyl methacrylate (Tg of homopolymer: 48℃) ・2EHMA: 2-Ethylhexyl methacrylate (Tg of homopolymer: -10°C)

[Hydroxyl-containing (meth)acrylate (a2)] ・HEA: 2-hydroxyethyl acrylate (Tg of homopolymer: -15°C)

[Ethylenically unsaturated monomer (a4)] ・2EHA: 2-ethylhexyl acrylate (Tg of homopolymer: -70℃) ・MA: Methyl acrylate (Tg of homopolymer: 8℃) ・MMA : Methyl methacrylate (Tg of homopolymer: 105°C)

・ADVN: 2,2'-azobis(2,4-dimethylvaleronitrile) (10-hour half-life temperature 52°C)

(Photoinitiator (B)) [Intramolecular hydrogen abstraction type photoinitiator (b1)] ・Omnirad 754: A product manufactured by IGM Resins B.V. [Intermolecular hydrogen abstraction type photoinitiator (b2)] ・Esacure TZT: Products manufactured by IGM Resins B.V. ・Omnipol BP: Products manufactured by IGM Resins B.V. ・MBP: Products manufactured by Xinling Corporation

(Crosslinking agent (C)) ・Polypropylene glycol #400 diacrylate (NK ester APG400, manufactured by Shin-Nakamura Chemical Co., Ltd.)

(Silane coupling agent (D)) ・KBM403 (manufactured by Shin-Etsu Chemical Co., Ltd.)

<Production Example C1: Production of Acrylic Resin (A-C1)> Mix iBMA: 25 parts, 2EHA: 35 parts, MA: 25 parts, and HEA: 15 parts to prepare a monomer solution. In a 2 L flask with a cooler, put methyl ethyl ketone as a polymerization solvent: 40 parts (boiling point 80°C), ADVN as a polymerization initiator: 0.008 parts, and 100 parts of a pre-prepared monomer solution 10%, after heating to reflux in the flask, add dropwise a mixed solution of ADVN: 0.11 parts, ethyl acetate: 10 parts, and 90% of the remaining monomer solution over 3 hours. Furthermore, after dripping for 30 minutes, the mixture of ethyl acetate: 10 parts and ADVN: 0.13 parts was dripped and reacted over 1 hour, and the solution of an acrylic resin (A-C1) was obtained. Table 11 shows the measurement results of the weight average molecular weight (Mw), degree of dispersion, and glass transition temperature based on dynamic viscoelasticity of the acrylic resin (A-C1).

<Manufacturing Examples C2-C4, Comparative Manufacturing Examples C1, C2> The composition of the copolymerization component including the monomer solution was set as shown in Table 11, and the acrylic resin (A -C2) to acrylic resin (A-C4), acrylic resin (A'-C1), acrylic resin (A'-2). Table 11 shows the measurement results of the weight average molecular weight (Mw), degree of dispersion, and glass transition temperature based on dynamic viscoelasticity of each acrylic resin.

[Table 11] acrylic resin Copolymer composition (parts) Mw (×10 ⁴ ) Dispersion Glass transition temperature (°C) iBMA (a1) (Tg: 48°C) 2EHMA (a1) (Tg: -10°C) 2EHA (a4) (Tg: -70°C) MA (a4) (Tg: 8°C) MMA (a4) (Tg: 105°C) HEA (a2) (Tg: -15°C) (A-C1) 25 - 35 25 - 15 20 2.77 2 (A-C2) - 40 10 35 - 15 19 2.20 4 (A-C3) 30 - 35 20 - 15 twenty three 2.86 3 (A-C4) 30 - 35 15 - 20 twenty one 2.82 4 (A'-C1) - - 60 - 25 15 16 2.66 0 (A'-C2) - - 60 25 - 15 12 2.59 -15

<Example C1> With respect to 100 parts of acrylic resin (A-C1) solution (solid content conversion), polypropylene glycol #400 diacrylate: 5.0 parts (solid content conversion), KBM403: 0.1 part (solid content conversion) In terms of solid content), Esacure TZT: 1.0 parts (in terms of solid content), and Omnirad 754: 2.0 parts (in terms of solid content) were mixed to obtain an adhesive composition. Adjust the obtained adhesive composition solution with ethyl acetate to a solid content concentration of 50%, apply it on a polyester release sheet so that the thickness after drying becomes about 50 μm, and dry at 100°C for 5 minutes , forming an adhesive composition layer.

Prepare two polyester-based release sheets on which the adhesive composition layer was formed as described above, and laminate the two adhesive composition layers facing each other. In the state where both sides of the laminated adhesive composition layer are sandwiched by polyester release sheets, the peak illuminance: 150 mW/cm ² and the cumulative exposure amount: 1000 mJ/cm are used by a high-pressure mercury UV irradiation device. ² (500 mJ/cm ² x 2 strokes) to irradiate with ultraviolet rays to form an adhesive layer (primary hardening), and to produce a substrate-free double-sided adhesive sheet with an adhesive layer thickness of 100 μm. Then, peel off the release sheet on one side from the adhesive layer of the obtained substrate-free double-sided adhesive sheet, and press the exposed adhesive layer side to the easy-to-adhesive polyethylene terephthalate (PET) sheet (125 μm in thickness), and a PET sheet with an adhesive layer of 100 μm in thickness. Also, peel off one side of the release sheet from the adhesive layer of the once-hardened double-sided adhesive sheet without substrate, and press the exposed adhesive layer side to the side of the polarizing plate with TAC-based film on the double-sided layer of the polarizing element. A TAC-based film surface, and the thickness of the adhesive layer is 100 μm to make a polarizing plate with an adhesive layer.

<Examples C2-C6, Comparative Examples C1-C4> As shown in Table 12, except that the type of acrylic resin (A) was changed, the adhesive composition of each example was prepared in the same manner as in Example C1 . Then, in the same manner as in Example C1, a substrate-free double-sided adhesive sheet with an adhesive layer thickness of 100 μm, a PET sheet with an adhesive layer, and a polarizing plate with an adhesive layer were produced sequentially.

[Table 12] Acrylic resin (A) Photoinitiator (B) (parts) Cross-linking agent (C) (parts) Silane coupling agent (D) (parts) Intramolecular hydrogen abstraction photoinitiator (b1) Intermolecular hydrogen abstraction photoinitiator (b2) type Content (parts) Omnirad 754 TZT MBP Omnipol BP Example C1 (A-C1) 100 2 1 - - 5 0.1 Example C2 (A-C2) 100 2 1 - - 5 0.1 Example C3 (A-C3) 100 2 1 - - 5 0.1 Example C4 (A-C3) 100 2 - 1 - 5 0.1 Example C5 (A-C3) 100 2 - - 1 5 0.1 Example C6 (A-C4) 100 2 1 - - 5 0.1 Comparative example C1 (A-C1) 100 2 - - - 5 0.1 Comparative example C2 (A-C1) 100 - 1 - - 5 0.1 Comparative example C3 (A'-C1) 100 2 1 - - 5 0.1 Comparative example C4 (A'-C2) 100 2 1 - - 5 0.1

<Measurement method and evaluation method> The measurement methods and evaluation methods of the compositions of Examples C1 to C6 and Comparative Examples C1 to C4 are shown below. The results are shown in Tables 13-15.

(Gel fraction: before complete hardening (after primary hardening)) After cutting the non-substrate double-sided adhesive sheet of each example into 40 mm×40 mm, let it stand for 30 minutes under the condition of 23°C×50%RH Afterwards, one of the release sheets was peeled off, and the exposed adhesive layer was attached to a 50 mm×100 mm SUS mesh (200 mesh). Peel off the rest of the release sheet, fold back from the center relative to the length direction of the SUS mesh, and wrap the adhesive layer with the SUS mesh. It was immersed in a sealed container containing 250 g of toluene maintained at 23°C for 24 hours, and the gel fraction (%) was calculated from the weight change at this time.

(Constant load holding power (50°C): before complete hardening (after primary hardening)) For the PET sheet with adhesive layer in each example, cut to a width of 25 mm x length of 75 mm (the width of the adhesive layer is 25 mm) × length 50 mm + width of non-adhesive layer part 25 mm × length 25 mm), peel off the release sheet. Press back and forth with a 2 kg roller to attach the exposed adhesive layer side to a stainless steel plate (SUS304) (attachment area 25 mm×50 mm), and let stand at 50°C for 20 minutes. Then, hang a weight of 50 g on the end of the length direction of the non-attached part (area 25 mm × 25 mm), and apply a load of 50 g along the direction of 90° to the plane of the stainless steel plate. After standing for 60 minutes, measure the peeling distance of the PET sheet. The evaluation criteria are as follows. A・・・The peeling distance is less than 10 mm. B・・・The peeling distance is more than 10 mm and less than 50 mm. C・・・The PET sheet is completely peeled off and falls off.

(Probe touch tack: before complete hardening (after first hardening)) For the PET sheet with adhesive layer in each example, cut it into a size of 10 mm in width x 10 mm in length, peel off the release sheet, and use a probe Needle contact tack tester (manufactured by TESTER SANGYO, probe contact tack tester TE-6001), pressurization time 1 second, attaching pressure 1000 gf, pressing speed 120 mm/min, pulling speed 600 mm /min and the probe diameter is 5.1 mm (diameter) to measure the contact viscosity of the probe (unit: N). The evaluation criteria are as follows. A・・・Probe touch tack (unit: N) is less than 5. B・・・Probe tackiness (unit: N) is 5 or more and less than 7.5. C・・・Probe touch tack (unit: N) is 7.5 or more and less than 10. D・・・Probe touch tack (unit: N) is 10 or more.

(Gel fraction: after complete hardening) For each double-sided adhesive sheet without substrate, the peak illuminance: 150 mW/cm ² , cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² ×4 strokes) after ultraviolet irradiation, cut into 40 mm × 40 mm, and let it stand for 30 minutes under the condition of 23°C × 50%RH. Thereafter, one of the release sheets was peeled off, and the exposed adhesive layer was attached to a 50 mm×100 mm SUS mesh (200 mesh). Peel off the rest of the release sheet, fold back from the center relative to the length direction of the SUS mesh, and wrap the adhesive layer with the SUS mesh. It was immersed in a sealed container containing 250 g of toluene maintained at 23°C for 24 hours, and the gel fraction (%) was calculated from the weight change at this time.

(180-degree peel strength (23°C): after complete hardening) For the PET sheet with the adhesive layer in each case, cut it into a size of 25 mm in width x 100 mm in length, and use a high-pressure mercury UV irradiation device to measure the peak illuminance: 150 mW/cm ² , cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² ×4 strokes) after ultraviolet irradiation, the release sheet was peeled off. In an environment of 23°C and 50%RH, use a 2 kg rubber roller to reciprocate twice to apply pressure to attach the exposed adhesive layer side to an alkali-free glass ("Eagle XG" manufactured by Corning, thickness 1.1 mm), and Leave to stand for 30 minutes under the same conditions. Thereafter, the 180-degree peel strength (N/25 mm) was measured at normal temperature (23° C.) at a peel speed of 300 mm/min.

(Constant load retention (80°C): after complete hardening) For the PET sheet with the adhesive layer in each case, it was cut to a width of 25 mm × length 75 mm (width of the adhesive layer part 25 mm × length 50 mm + non- The width of the adhesive layer is 25 mm x length 25 mm), and the peak illuminance: 150 mW/cm ² , cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² x 4 strokes) using a high-pressure mercury UV irradiation device After irradiating with ultraviolet light under the same conditions, peel off the release sheet. Press back and forth with a 2 kg roller to attach the exposed adhesive layer side to a stainless steel plate (SUS304) (attachment area 25 mm×50 mm), and let stand at 80°C for 20 minutes. Then, hang a weight of 50 g on the end of the length direction of the non-attached part (area 25 mm × 25 mm), and apply a load of 50 g along the direction of 90° relative to the plane of the stainless steel plate. Let it stand for 60 minutes, and measure the peeling distance of the PET sheet. The evaluation criteria are as follows. A・・・The peeling distance is less than 5 mm. B・・・The peeling distance is more than 5 mm and less than 10 mm. C・・・The peeling distance is 10 mm or more, or the PET sheet falls off.

(Retention force (80°C): after complete hardening) For the PET sheet with adhesive layer in each case, cut it into a size of 25 mm×50 mm, use a high-pressure mercury UV irradiation device to measure the peak illuminance: 150 mW/cm ² , Cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² × 4 strokes) after ultraviolet irradiation, peel off the release sheet. Put the stainless steel plate (SUS304) on the side of the exposed adhesive layer, press it back and forth with a 2 kg roller to attach it (attachment area 25 mm × 25 mm), use a creep tester (manufactured by TESTER SANGYO company, attached Constant Humidity Chamber Retention Tester BE-501), apply a load of 1 kg for 24 hours at 80°C to measure the retention. The evaluation criteria are as follows. A・・・No offset. B・・・The deviation is less than 1.0 mm. C・・・The deviation is more than 1.0 mm or the PET sheet falls off.

(Moisture and heat resistance: after complete hardening) For each PET sheet with an adhesive layer, cut it into a size of 30 mm×50 mm, use a high-pressure mercury UV irradiation device with a peak illuminance: 150 mW/cm ² , cumulative exposure Amount: 4000 mJ/cm ² (1000 mJ/cm ² x 4 strokes) After ultraviolet irradiation, the release sheet was peeled off. The side of the exposed adhesive layer was bonded to an alkali-free glass ("Eagle XG" manufactured by Corning, thickness 1.1 mm). Afterwards, autoclave treatment at 50°C, 0.5 MPa, and 20 minutes, and let stand at 23°C, 50%RH for 30 minutes to produce a layer with "alkali-free glass/adhesive layer/PET" Composed of test pieces. Using the obtained test piece, conduct a heat and humidity resistance test for 7 days (168 hours) in an environment of 60°C and 90% RH, and measure the haze value before and after the heat and humidity resistance test.

The haze value is measured by using HAZE MATER NDH4000 (manufactured by Nippon Denshoku Industries Co., Ltd.) to measure the diffuse transmittance and total light transmittance, and substitute the obtained values of diffuse transmittance (DT) and total light transmittance (TT) into the following Calculated by formula 1. Furthermore, the rate of increase (%) of the haze value was calculated from the following formula 2. This machine conforms to JIS K7361-1. Haze value (%) = (DT/TT) × 100 ・・・[Formula 1] Haze value difference (%) = Haze value after the heat and humidity resistance test - Haze value before the heat and humidity resistance test started・・・[Formula 2] Evaluation criteria are as follows. A・・・The difference in haze value is less than 0.5%. B・・・The difference in haze value is 0.5% or more and less than 3.0%. C・・・The difference in haze value is 3.0% or more.

(Probe touch tack: after complete hardening) For the PET sheet with the adhesive layer in each case, cut it into a size of 12 mm in width x 12 mm in length, and use a high-pressure mercury UV irradiation device to measure the peak illuminance: 150 mW/cm ^2. Cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² × 4 strokes) after ultraviolet irradiation, peel off the release sheet, and use a probe contact adhesion tester (manufactured by TESTER SANGYO company, probe touch Viscosity tester TE-6001), measured under the conditions of pressurization time 1 second, attachment pressure 1000 gf, pressing speed 120 mm/min, pulling speed 600 mm/min, probe diameter 5.1 mm (diameter) Probe contact viscosity (unit: N). The evaluation criteria are as follows. A・・・Probe tackiness (unit: N) is less than 5. B・・・Probe touch tack (unit: N) is 5 or more and less than 7.5. C・・・Probe touch tack (unit: N) is 7.5 or more and less than 10. D・・・Probe tackiness (unit: N) is 10 or more.

(Durability of polarizing plate: after complete hardening) The polarizing plate with adhesive layer in each example was cut to a size of 60 mm in width x 100 mm in length, and the release sheet was peeled off. In an environment of 23°C and 50%RH, use a 2 kg rubber roller to reciprocate twice to apply pressure to attach the exposed adhesive layer side to an alkali-free glass ("Eagle XG" manufactured by Corning, thickness 1.1 mm), After autoclave treatment (0.5 MPa×50℃×20 minutes), use a high-pressure mercury UV irradiation device with peak illuminance: 150 mW/cm ² , cumulative exposure: 4000 mJ/cm ² (1000 mJ/cm ² ×4 strokes ) was irradiated with ultraviolet rays from the non-alkali glass side, and a sample for durability evaluation of a polarizing plate was produced. After exposing the obtained sample for durability evaluation of the polarizing plate to 80°C, dry conditions and 60°C, 90%RH conditions for 7 days respectively, the end of the polarizing plate was observed and evaluated according to the following criteria. A・・・The bulge at the end of the polarizer does not reach 1 mm. B・・・The bulge at the end of the polarizer is 1 mm or more and less than 2 mm. C・・・The bulge at the end of the polarizer is 2 mm or more.

之方式彎曲，以該狀態加以固定後，進行高壓釜處理(0.5 MPa×50℃×20分鐘)，利用高壓水銀UV照射裝置以峰照度：150 mW/cm ²、累計曝光量：4000 mJ/cm ²(1000 mJ/cm ²×4行程)對彎曲之狀態之樣品進行紫外線照射，而製作曲面耐久評價用樣品。曲面耐久評價用樣品具有自外側起依序為PET/黏著層/偏光板/鋁板之層構成。最內側有鋁板。  使用所獲得之曲面耐久評價用樣品，於80℃、乾燥、7天之條件下及60℃、90%RH、7天之條件下分別暴露後，觀察已進行紫外線照射之彎曲部及除彎曲部以外之偏光板端部，按照以下基準進行評價。 (Curved surface durability: after complete hardening) For the polarizing plate with adhesive layer in each case, cut it into a size of 40 mm in width x 120 mm in length, and peel off the release sheet. Apply pressure to the exposed adhesive layer side with a rubber roller in an environment of 23°C and 50%RH, and attach it to an easy-to-adhesive polyethylene terephthalate (PET) sheet (thickness 125 μm) . Thereafter, the PET surface was used as the surface, and the aluminum plate (width 70 mm, length 150 mm, thickness 0.3 mm) was attached and fixed with adhesive tape to make an aluminum plate fixed sample. Use the mandrel testing machine to make the sample to be 5 mm

After being bent in the same way and fixed in this state, autoclave treatment (0.5 MPa×50℃×20 minutes) was performed, and the peak illuminance: 150 mW/cm ² and cumulative exposure: 4000 mJ/cm were used by a high-pressure mercury UV irradiation device. ² (1000 mJ/cm ² ×4 strokes) irradiate the bent sample with ultraviolet light to make a curved surface durability evaluation sample. The sample for curved surface durability evaluation has a layer configuration of PET/adhesive layer/polarizing plate/aluminum plate in order from the outside. There is an aluminum plate on the innermost side. Using the obtained curved surface durability evaluation sample, after exposing it under the conditions of 80°C, dry, for 7 days and 60°C, 90%RH, for 7 days, observe the curved part and the non-bent part after ultraviolet irradiation The other end portions of the polarizing plate were evaluated in accordance with the following criteria.

(Evaluation criteria: bending part) A・・・Swelling, foaming, and paste overflow were not observed. B・・・Swelling, foaming, or overflow of paste is observed.

(Evaluation criteria: end of polarizing plate) A... Neither swelling nor air bubbles were observed at the edge part. B・・・Very few air bubbles were observed at the end. C・・・Bubbles were observed at one part of the end. D・・・Swelling and air bubbles are generated on the whole end.

(Evaluation criteria: comprehensive evaluation) A・・・Evaluation of the bent part is A and evaluation of the end of the polarizing plate is A. B・・・Evaluation of the bent portion is A and evaluation of the edge of the polarizing plate is B or C. C・・・Evaluation of the curved part is A and evaluation of the end of the polarizing plate is D. D・・・Evaluation of the bent part is B, and evaluation of the edge part of the polarizing plate is any one of A to D.

[Table 13] Adhesive properties before complete hardening (after first hardening) Adhesive properties after complete hardening Gel fraction (%) Constant load retention (50℃) Probe Tackiness Gel fraction (%) 180 degree peel strength (23℃) Constant load retention (80℃) Holding power 80℃ Peeling distance evaluate (N) evaluate (N/25mm) Peeling distance evaluate offset evaluate Example C1 0.8 31 mm B 5.5 A 43.9 29.7 3 mm A 0.85 mm B Example C2 1.0 41 mm B 4.0 A 42.6 31.2 5 mm B 0.9mm B Example C3 0.9 20 mm B 3.2 A 52.8 26.1 5 mm A 0.85 mm B Example C4 3.4 14 mm B 4.5 A 56.6 24.2 3 mm A no offset A Example C5 0.7 30 mm B 3.9 A 59.9 26.2 3 mm A no offset A Example C6 0.7 14 mm B 4.4 A 53.8 26.9 4 mm A 0.6 mm B Comparative example C1 1.0 drop C 4.4 A 32.8 32.2 7 mm B drop C Comparative example C2 0.7 drop C 4.8 A 1.5 40.8 drop C drop C Comparative example C3 0.7 drop C 6.7 A 48.6 25.3 3 mm A 0.5 mm B Comparative example C4 0.5 drop C 14.6 B 49.9 29.5 15 mm C 0.6 mm B

[Table 14] Adhesive properties after complete hardening Humidity and heat resistance test Probe Tackiness Haze value before test (%) Haze value after test (%) Haze value difference (%) evaluate (N) evaluate Example C1 0.5 0.8 0.3 A 4.9 A Example C2 0.4 0.7 0.3 A 4.3 A Example C3 0.5 0.7 0.2 A 5.3 B Example C4 0.6 0.8 0.2 A 4.0 A Example C5 0.6 0.7 0.1 A 4.4 A Example C6 0.7 0.8 0.1 A 3.0 A Comparative example C1 0.5 0.7 0.2 A 3.3 A Comparative example C2 0.5 0.7 0.2 A 3.7 A Comparative example C3 0.6 0.8 0.2 A 4.6 A Comparative example C4 0.6 0.8 0.2 A 16.2 D.

[Table 15] Adhesive properties after complete hardening Surface durability 80°C, dry Curved Surface Durability 60℃/90%RH Polarizer durability 80°C, dry Polarizer Durability 60℃/90%RH curved part Ends Overview curved part Ends Overview end bulge evaluate end bulge evaluate Example C1 A A A A A A less than 1 mm A less than 1 mm A Example C2 A B B A A A More than 1 mm and less than 2 mm B More than 1 mm and less than 2 mm B Example C3 A A A A A A less than 1 mm A less than 1 mm A Example C4 A A A A A A less than 1 mm A less than 1 mm A Example C5 A A A A A A less than 1 mm A less than 1 mm A Example C6 A B B A A A less than 1 mm A less than 1 mm A Comparative example C1 B C D. B C D. More than 2 mm and less than 10 mm C More than 2 mm and less than 10 mm C Comparative example C2 B C D. B C D. 10 mm or more C 10 mm or more C Comparative example C3 B B D. A C D. More than 2 mm and less than 10 mm C More than 2 mm and less than 10 mm C Comparative example C4 B C D. B C D. 10 mm or more C 10 mm or more C

Adhesive sheets using the adhesive compositions of Examples C1-C6 also exhibited excellent adhesive properties with low touch tack and high constant load retention in the low crosslinked state before complete hardening (after primary hardening) . In addition, it also exhibits excellent adhesive properties after complete hardening. On the other hand, in Comparative Examples C1 and C2, only one of intramolecular hydrogen abstraction type photoinitiator or intermolecular hydrogen abstraction type photoinitiator was used. In Comparative Examples C3 and C4, no branched alkyl (meth)acrylate whose homopolymer Tg was -30°C or higher was used. Compared with Examples C1-C6, the adhesive sheets using the adhesive compositions of Comparative Examples C1-C4 had inferior adhesive properties in the low-crosslinked state after primary curing. [Industrial availability]

The adhesive formed by using the adhesive composition of the present invention has excellent adhesive properties in a low-crosslinked state after primary curing. The adhesive agent which uses the adhesive agent composition of this invention can be used especially as the adhesive agent used for lamination of the optical member which comprises a touch panel, an image display device, etc., or an organic EL display sealing application, etc.

Claims (26)

An adhesive composition, which contains an acrylic resin (A) and a photoinitiator (B), The above-mentioned acrylic resin (A) is a polymerization product of the following copolymerization component (a), The above-mentioned copolymerization component (a) contains alkyl acrylate (a1) whose glass transition temperature when forming a homopolymer is -30 to 50°C and methacrylic acid whose glass transition temperature is -10 to 120°C when forming a homopolymer Alkyl ester (a2), The total content of the said alkyl acrylate (a1) and the said alkyl methacrylate (a2) is 5 weight% or more with respect to 100 weight% of the said copolymerization components (a). The adhesive composition according to claim 1, wherein the above-mentioned copolymerization component (a) further contains a hydroxyl-containing monomer (a3). The adhesive composition according to claim 2, wherein the content of the above-mentioned hydroxyl-containing monomer (a3) is 0.1% by weight or more relative to 100% by weight of the above-mentioned copolymerization component (a). The adhesive composition according to claim 1, wherein the acrylic resin (A) has a glass transition temperature based on dynamic viscoelasticity of -10°C or higher. The adhesive composition according to claim 1, wherein the weight average molecular weight of the acrylic resin (A) is 50,000-500,000. The adhesive composition according to claim 1, wherein the weight average molecular weight of the acrylic resin (A) is 50,000-400,000. The adhesive composition according to claim 1, wherein the weight ratio of the above-mentioned alkyl acrylate (a1) to the above-mentioned alkyl methacrylate (a2) is 5/95˜55/45. The adhesive composition according to claim 1, wherein the total content of the above-mentioned alkyl acrylate (a1) and the above-mentioned alkyl methacrylate (a2) is 30 to 70% by weight relative to the above-mentioned copolymerization component (a). The adhesive composition according to claim 1, wherein the above-mentioned copolymerization component (a) further includes a hydroxyl-containing monomer (a4) containing an alkyl chain, a hydroxyl group, and an ethylenically unsaturated group. The adhesive composition according to claim 2, wherein the average carbon number of the alkyl chain of the above-mentioned hydroxyl-containing monomer (a3) in the above-mentioned copolymerization component (a) is 2.1 or more. The adhesive composition according to claim 1, wherein any one of the above-mentioned alkyl acrylate (a1) and the above-mentioned alkyl methacrylate (a2) has a branched alkyl group. The adhesive composition according to claim 1, wherein the photoinitiator (B) contains an intramolecular hydrogen abstraction type photoinitiator (b1) or an intermolecular hydrogen abstraction type photoinitiator (b2). The adhesive composition according to claim 1, wherein the photoinitiator (B) contains an intramolecular hydrogen abstraction type photoinitiator (b1) and an intermolecular hydrogen abstraction type photoinitiator (b2). The adhesive composition according to Claim 1, further comprising a crosslinking agent (C). An adhesive, which is formed by cross-linking the adhesive composition according to any one of claims 1 to 14. The adhesive according to claim 15, wherein the cross-linking is performed by irradiation of active energy rays. An adhesive sheet having an adhesive layer comprising the adhesive according to claim 15 or 16. The adhesive sheet according to claim 17, wherein the above-mentioned adhesive layer is multistage hardening that is hardened in a plurality of stages. An adhesive sheet with a release film, which has a laminated structure in which at least one side of the adhesive sheet according to claim 17 or 18 is layered with a release film. A laminate for an image display device, which has a laminated structure in which two components of an image display device are laminated via an adhesive sheet according to claim 17 or 18, One of the above-mentioned two components of the image display device is a cover glass having a curved shape, The other of the above two components of the image display device is selected from a touch sensor, an image display panel, a surface protection film, an anti-reflection film, a color filter, a polarizing film, and a retardation film. At least one species in the group. A curved image display device comprising the laminate for an image display device according to claim 20. An adhesive composition for a curved optical member, which contains an acrylic resin (A), The above-mentioned acrylic resin (A) is a polymerization product of the following copolymerization component (a), The above-mentioned copolymerization component (a) contains an alkyl acrylate (a1) and an alkyl methacrylate (a2). The adhesive composition for curved optical members according to claim 22, wherein the copolymerization component (a) further contains a hydroxyl group-containing monomer (a3). The adhesive composition for curved optical members according to claim 22 or 23, wherein the weight ratio of the above-mentioned alkyl acrylate (a1) to the above-mentioned alkyl methacrylate (a2) is 5/95˜55/45. The adhesive composition for curved surface optical members according to claim 22 or 23, wherein the total content of the above-mentioned alkyl acrylate (a1) and the above-mentioned alkyl methacrylate (a2) is 10% by weight relative to the above-mentioned copolymerization component (a) %above. The adhesive composition for curved surface optical members according to claim 22 or 23, further comprising a photopolymerization initiator.