JP6633366B2 - Pressure-sensitive adhesive composition, pressure-sensitive adhesive layer, pressure-sensitive adhesive sheet, and image display device - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet, and an image display device.

  Currently, flat display panels such as a liquid crystal display panel (LCD) and a plasma display panel (PDP) are mainly used as display panels. Usually, a laminated body in which a plurality of films are laminated is attached to the surface of the flat display panel. For example, in an LCD, an optical film such as a polarizing plate, a retardation plate, a viewing angle widening film, and a brightness improvement film is usually laminated on the surface of a liquid crystal panel. And each layer which comprises a flat display panel is normally bonded by the adhesive layer formed by various adhesives.

  On the other hand, recently, in addition to a flat display, a curved display or a flexible display has been demanded from the viewpoint of design and versatility in use. An organic electroluminescent panel (OLED) is mainly used for a curved display or a flexible display.

  In addition to the optical properties and durability, the adhesive layer used for this curved display or flexible display, and the optical film laminate laminated by the adhesive layer or the adhesive layer, have good adhesiveness and bending. It is required that peeling and lifting do not occur even if it is performed.

  As a pressure-sensitive adhesive layer used in a conventional optical film laminate (optical member) for a flat display panel, for example, in Patent Document 1, a linear or branched alkyl group having 2 to 18 carbon atoms ( Acrylic polymer having a weight average molecular weight of 300,000 or more and 2.5 million or less, wherein a monomer unit of a (meth) acrylic acid alkyl ester is used as a main skeleton, and a copolymer monomer which is copolymerized with the alkyl (meth) acrylate is used as a monomer unit. And a glass transition temperature (Tg) of -35 [deg.] C. or lower is disclosed as a base polymer.

  Patent Document 2 discloses a pressure-sensitive adhesive for an optical film containing 0.001 to 50 parts by weight of a titanium-based coupling agent and / or a zirconium-based coupling agent with respect to 100 parts by weight of a base polymer. A composition is disclosed.

JP 2011-017009 A JP 2010-065102 A

  However, the techniques of Patent Documents 1 and 2 have a problem that bending at a low temperature such as −20 ° C. cannot be performed, or peeling or floating occurs in the pressure-sensitive adhesive layer or the bonding portion even when bending is performed.

  Therefore, the present invention provides a pressure-sensitive adhesive composition having an excellent balance between adhesive strength and bending resistance that hardly causes peeling or lifting even when bent, over the entire temperature range where use is assumed. It is an object to provide a pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet, and an image display device.

  The present inventors have intensively studied to solve the above-mentioned problems. As a result, it is selected from the group consisting of a main agent (A) composed of a curable compound, a trisubstituted aromatic compound, a phosphoric acid triester, an aliphatic tricarboxylic acid ester, an alicyclic tricarboxylic acid ester, and a polyoxyalkylene sorbitan fatty acid ester. A pressure-sensitive adhesive composition comprising at least one kind of additive (B), wherein the storage elastic modulus at the 80 ° C. after curing G ′ (80) and the storage elastic modulus at the −20 ° C. after curing G ′ The present inventors have found that the above object can be achieved by a pressure-sensitive adhesive composition having (-20) a specific value and a shear strength after curing in a specific range, and completed the present invention.

That is, the present invention relates to a method wherein the main agent (A) comprising a curable compound and a trisubstituted aromatic compound, a triaryl phosphate, an aliphatic tricarboxylic acid ester, an alicyclic tricarboxylic acid ester, and a polyoxyalkylene sorbitan fatty acid ester are used. A pressure-sensitive adhesive composition containing at least one additive (B) selected from the group consisting of: a content of the additive (B) of 0 to 100 parts by mass of the main agent (A). 0.1 part by mass or more and 8 parts by mass or less, the storage elastic modulus G ′ (80) at 80 ° C. after curing is 1.72 × 10 ⁴ Pa or more and 4.0 × 10 ⁴ Pa or less, and after curing. The storage elastic modulus G ′ (− 20) at −20 ° C. is smaller than 13 times that of the above G ′ (80), and the shear strength when subjected to a shear deformation of 1000% at a shear rate of 30 mm / min after curing is higher. It is less than 0 kPa, a pressure-sensitive adhesive composition.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesive composition which was excellent in the balance of the adhesive strength and the bending resistance which hardly causes peeling or floating even if it bends over the temperature range where use is assumed. , An adhesive layer, an adhesive sheet, and an image display device.

  Hereinafter, embodiments for carrying out the present invention will be described in detail.

[Adhesive composition]
The pressure-sensitive adhesive composition of the present invention comprises a main agent (A) composed of a curable compound, a trisubstituted aromatic compound, a phosphoric acid triester, an aliphatic tricarboxylic acid ester, an alicyclic tricarboxylic acid ester, and a polyoxyalkylene sorbitan fatty acid. A pressure-sensitive adhesive composition comprising at least one additive (B) selected from the group consisting of esters, wherein the content of the additive (B) is based on 100 parts by mass of the main agent (A). 0.1 to 8 parts by mass, and the storage elastic modulus G ′ (80) at 80 ° C. after curing is 1.72 × 10 ⁴ Pa or more and 4.0 × 10 ⁴ Pa or less. Has a storage elastic modulus G ′ (− 20) at −20 ° C. smaller than 13 times that of G ′ (80), and has a shear strength of 1000% at a shear rate of 30 mm / min after curing. 60kP A pressure-sensitive adhesive composition is less than. By having such a configuration, the pressure-sensitive adhesive composition of the present invention can have an adhesive force and bend over the entire temperature range where use is assumed (for example, −20 ° C. or more and 80 ° C. or less). The effect of being excellent in the balance between the bending resistance, which hardly causes peeling and floating, and the effect is obtained.

  Adhesives used in bendable image display devices are required to withstand not only deformation due to stress in conventional non-bendable image display devices but also deformation due to bending in the entire temperature range where they are used. . Conventionally, in the techniques of Patent Document 1 and Patent Document 2 described above, since the storage elastic modulus of the pressure-sensitive adhesive layer is increased particularly in a low-temperature environment, the pressure-sensitive adhesive layer cannot be bent in a low-temperature environment, or cannot be bent by bending. There has been a problem that peeling or lifting of the joint occurs.

  The present inventors have conducted intensive studies on such a problem, and as a result, based on the main agent (A) composed of a curable compound, a trisubstituted aromatic compound, a phosphoric acid triester, an aliphatic tricarboxylic acid ester, a fatty acid It has been found that a pressure-sensitive adhesive composition containing a specific amount of at least one additive (B) selected from the group consisting of cyclic tricarboxylic acid esters and polyoxyalkylene sorbitan fatty acid esters solves the above problems. .

  The reason why the above-mentioned effects can be obtained by the pressure-sensitive adhesive composition of the present invention is unknown, but it is considered as follows. That is, the additive (B) according to the present invention has both a bulky (bulky) structure, which is not a mere planar structure, and an affinity (compatibility) with the cured product of the curable compound. It has an effect of restraining not only the planar direction but also the relatively soft pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition in the thickness direction. This makes it possible to form a pressure-sensitive adhesive layer having an excellent balance between the adhesive strength and the bending resistance that hardly causes peeling or lifting even when bent over the entire temperature range where use is assumed. It is believed that an agent composition can be obtained.

  The pressure-sensitive adhesive composition used for bonding a member for a bendable image display device has excellent adhesiveness that does not cause peeling of the member, and is supposed to realize bending in a low-temperature environment, particularly. Bending flexibility is required at all operating temperatures. In particular, in order to realize bending in a low temperature environment, it is necessary that the cured adhesive is in a rubber state even at a low temperature, and yet the adhesive does not flow under a high temperature environment. It is necessary to maintain a sufficiently high storage modulus. In order to achieve this, in the present invention, the main component (A) made of a curable compound which is in a rubbery state even in a low temperature (for example, −20 ° C.) operating temperature range is used as a cured product obtained after curing. However, conventionally, when the material design of the acrylic polymer contained in the pressure-sensitive adhesive layer is performed so as to lower the glass transition temperature of the acrylic pressure-sensitive adhesive layer, the storage elastic modulus tends to decrease in all temperature ranges. In other words, there was a trade-off between reducing the storage modulus in the low temperature region and maintaining the storage modulus in the high temperature region. The present invention also solves the problem of such trade-off, and while maintaining the high-temperature storage elastic modulus after curing at a high value, can reduce the low-temperature storage elastic modulus after curing, an effective additive. It can be said that it was found.

  Note that the above mechanism is presumed, and the present invention is not limited to the above mechanism at all.

  Here, the bending resistance (bending resistance) can be evaluated by a bending test (high temperature, low temperature). Specifically, the high temperature in the bending test is 50 ° C. or higher or 60 ° C. or higher. The upper limit is 110 ° C or lower, or 105 ° C or lower. Further, the low temperature in the bending test is specifically 0 ° C. or lower, or −10 ° C. or lower, and the lower limit is −40 ° C. or higher.

In the pressure-sensitive adhesive composition of the present invention, the storage elastic modulus G ′ (80) at 80 ° C. after curing is 1.72 × 10 ⁴ Pa or more and 4.0 × 10 ⁴ Pa or less, and −20 after curing. The storage elastic modulus G ′ (− 20) at ° C. is smaller than 13 times the above G ′ (80).

In the pressure-sensitive adhesive composition of the present invention, when the storage elastic modulus G ′ (80) at 80 ° C. after curing is less than 1.72 × 10 ⁴ Pa, the pressure-sensitive adhesive flows at the time of bending and peels off, so that the bending resistance is reduced. When G ′ (80) exceeds 4.0 × 10 ⁴ Pa, the adhesive strength decreases, and peeling occurs at the bonding interface during bending, so that the bending resistance decreases. G ′ (80) is preferably from 1.73 × 10 ⁴ Pa to 3.0 × 10 ⁴ Pa, more preferably from 2.0 × 10 ⁴ Pa to 2.5 × 10 ⁴ Pa.

  In the pressure-sensitive adhesive composition of the present invention, the storage elastic modulus G ′ (− 20) at −20 ° C. after curing is smaller than 13 times the G ′ (80). When G ′ (− 20) is 13 times or more the above-mentioned G ′ (80), the bending resistance at low temperatures decreases. G ′ (− 20) is preferably 2.22 to 12.02 times G ′ (80), more preferably 9.60 to 10.80 times G ′ (80).

  In addition, the values measured by the method described in Examples are used for the storage elastic moduli G ′ (80) and G ′ (− 20). The storage elastic moduli G ′ (80) and G ′ (− 20) are determined based on the composition of the main component (A), the composition of the (meth) acrylate copolymer (C) which can be contained in the main component (A), and the additive ( It can be controlled by the type and amount of B), the type and amount of crosslinking agent (D), and the like.

  Furthermore, in the pressure-sensitive adhesive composition of the present invention, the shear strength when subjected to a shear deformation of 1000% at a shear rate of 30 mm / min after curing is less than 60 kPa. When the shear strength is 60 kPa or more, the bending resistance at low temperatures decreases. The shear strength is preferably at most 59 kPa, more preferably at most 42 kPa. On the other hand, the lower limit of the shear strength is not particularly limited, but is preferably 29 kPa or more, more preferably 37 kPa or more. As the shear strength, a value measured by the method described in Examples is adopted. The shear strength is determined by the composition of the base material (A), the composition of the (meth) acrylate copolymer (C) that can be contained in the base material (A), the type and amount of the additive (B), and the crosslinking agent (D). ) Can be controlled by the type and the amount of addition.

  The glass transition temperature after curing of the pressure-sensitive adhesive composition of the present invention is preferably −50 ° C. or lower. Within this range, the bending resistance at high and low temperatures is excellent. The glass transition temperature is more preferably from -70 ° C to -50 ° C, even more preferably from -58 ° C to -52 ° C. The glass transition temperature after curing can be measured by the method described in Examples.

  Hereinafter, each component of the pressure-sensitive adhesive composition of the present invention will be described in detail.

  In this specification, “(meth) acrylate monomer” is a general term for an acrylate monomer and a methacrylate monomer. Similarly, a compound containing (meth) such as (meth) acrylic acid is a general term for a compound having “meth” in a name and a compound not having “meth” in a name. For this reason, “(meth) acryl” includes both acryl and methacryl. The “(meth) acrylate monomer” includes both an acrylate monomer and a methacrylate monomer. “(Meth) acrylic acid” includes both acrylic acid and methacrylic acid. Further, the “pressure-sensitive adhesive composition” is also simply referred to as “pressure-sensitive adhesive”. Further, “(meth) acrylate copolymer (C)” is also simply referred to as “copolymer (C)”.

[Main agent (A)]
Examples of the form of the main agent (A) comprising the curable compound according to the present invention include:
(1) (meth) acrylic acid alkyl ester monomer (c1) (hereinafter also simply referred to as “component (c1)”) and monomer (c2) copolymerizable with component (c1) (hereinafter simply referred to as component (c2) (Also referred to as a curable compound comprising only a monomer)
(2) The (meth) acrylic ester copolymer (C) having the component (c1), the component (c2), and a structural unit derived from the component (c1) and a structural unit derived from the component (c2). (Hereinafter, also referred to simply as a copolymer (C)) (a curable compound is a form comprising a monomer and a polymer, that is, a so-called polymer syrup form)
(3) Form consisting only of copolymer (C) (form in which curable compound consists only of polymer)
Is mentioned.

  It is considered that when such a main agent (A) is contained in the pressure-sensitive adhesive composition of the present invention, the pressure-sensitive adhesive layer obtained after curing has the significance of securing the adhesiveness and securing the basic characteristics.

  Above all, the curable compound contains the copolymer (C) from the viewpoint that the pressure-sensitive adhesive layer according to the present invention is easily formed, and the intended effects of the present invention can be more efficiently achieved. (The above (2) or (3)) is preferable.

<< Form of the above (1) >>
One embodiment according to the present invention includes an embodiment in which the main component (A) is composed of the component (c1) and the component (c2) (an embodiment in which the curable compound is composed of only a monomer). The component (c1) and the component (c2) form a copolymer (C) by performing a curing treatment.

<(C1) (meth) acrylic acid alkyl ester monomer>
The alkyl (meth) acrylate monomer (c1) is not particularly limited as long as the alkyl group is introduced into the ester site of the (meth) acrylate ester.

  The number of carbon atoms of the alkyl group is not particularly limited, but is preferably 1 or more and 20 or less, and particularly preferably 2 or more and 18 or less, and more preferably 3 or less, The number is more preferably 16 or more, and particularly preferably 4 or more and 12 or less. According to a preferred embodiment of the present invention, in the component (c1), the alkyl group has 1 to 18 carbon atoms. The alkyl group may be linear, branched, or cyclic, but is preferably linear or branched from the viewpoint of lowering the glass transition temperature. In the case of a ring, the carbon number is 3 or more.

  The alkyl (meth) acrylate monomer (c1) typically has the following formula (1):

Indicated by

Here, in the above equation (1),
R ₁ is a hydrogen atom or a methyl group, and R ₂ is the above-mentioned alkyl group.

  Examples of such an alkyl group include, but are not particularly limited to, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an isobutyl group, an n-hexyl group, 2-hexyl group, 3-hexyl group, cyclohexyl group, 1-methylcyclohexyl group, n-heptyl group, 2-heptyl group, 3-heptyl group, isoheptyl group, tert-heptyl group, n-octyl group, isooctyl group, Examples include a tert-octyl group, a 2-ethylhexyl group, a nonyl group, an isononyl group, a decyl group, a dodecyl group, a tridecyl group, a tetradecyl group, a pentadecyl group, a hexadecyl group, a heptadecyl group, and an octadecyl group. In particular, a methyl group, a butyl group, a 2-ethylhexyl group, an n-hexyl group, a nonyl group, and an isononyl group are preferable from the viewpoint of ensuring adhesiveness and basic characteristics.

  Accordingly, specific examples of the alkyl (meth) acrylate monomer (c1) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl (meth) acrylate. , Isobutyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (Meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, lauryl (meth) acrylate, and the like. These components (c1) can be used alone or in combination of two or more. As the component (c1), a commercially available product or a synthetic product may be used.

<(C2) Monomer copolymerizable with component (c1)>
The main component (A) according to the present invention preferably contains a monomer (c2) component copolymerizable with the (c1) component. The component (c2) includes (c2-1) a (meth) acrylic monomer having an amide group, and (c2-2) a functional group-containing monomer which is a (meth) acrylate monomer having no plurality of radically polymerizable functional groups. , (C2-3) a macromonomer having a polymerizable functional group, and (c2-4) a component (c1), a component (c2-1), a component (c2-2) and a component (c2-3) other than the component (c2-3). ) Acrylic ester monomers are preferred.

{(C2-1) (meth) acrylic monomer having amide group}
The main agent (A) according to the present invention preferably contains (c2-1) an (meth) acrylic monomer having an amide group (hereinafter, also simply referred to as a (c2-1) component). By including such a component (c2-1) in the main agent (A), the following effects are obtained. That is, the (meth) acrylic monomer having an amide group usually has a high glass transition temperature and a high polarity. Therefore, the cohesive force is improved as the bulk physical properties of the pressure-sensitive adhesive. On the other hand, as the interface characteristics, the affinity for the polar material is improved. Therefore, when the polymer contained in the pressure-sensitive adhesive layer after curing has the structural unit derived from the component (c2-1), the adhesive strength and the durability are improved. Such a mechanism is considered to occur similarly even when a carboxyl group-containing monomer such as acrylic acid is used. However, a carboxyl group-containing monomer such as acrylic acid has metal corrosiveness and may be unsuitable for some applications.

  The (meth) acrylic monomer (c2-1) having an amide group is not particularly limited as long as it has an amide group in the (meth) acrylic monomer. And the following formula (2):

Indicated by

Here, in the above equation (2),
R ₈ is a hydrogen atom or a methyl group,
R ₉ is a single bond or a divalent organic group,
R ₁₀ is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a hydroxyl group, an acyl group, an epoxy group, an alkoxy group having 1 to 6 carbon atoms or a dimethylamino group,
R ₁₁ is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms.

  The divalent organic group is not particularly limited, but is preferably an alkylene group having 1 to 10 carbon atoms. Further, the alkylene group or the acyl group may have at least one alkyl group having 1 to 8 carbon atoms, a phenyl group, or a cyclohexyl group as a substituent.

  Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert-butyl group, an isobutyl group, an n-hexyl group, a 2-hexyl group, 3-hexyl group, cyclohexyl group, 1-methylcyclohexyl group, n-heptyl group, 2-heptyl group, 3-heptyl group, isoheptyl group, tert-heptyl group, n-octyl group, isooctyl group, tert-octyl group, Preferred are 2-ethylhexyl, nonyl, isononyl, decyl and the like.

  The number of carbon atoms of the acyl group is also not particularly limited, but is preferably 1 or more and 18 or less, more preferably 1 or more and 6 or less. The acyl group includes an acetoacetoxy group.

  Examples of the alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, a propyloxy group, an isopropyloxy group, a butoxy group, a sec-butoxy group, a tert-butoxy group, an isobutoxy group, an n-hexyloxy group, Hexyloxy, 3-hexyloxy, cyclohexyloxy and the like are preferred.

  The alkylene group having 1 to 10 carbon atoms is a divalent substituent obtained by removing one hydrogen atom from the alkyl group having 1 to 10 carbon atoms.

R ₁₀ and R ₁₁ may form a ring with each other, and the ring may have an oxygen atom.

  From the above, N-hydroxymethyl (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, (meth) acryloylmorpholine, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, diacetone ( (Meth) acrylamide, (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-isopropyl (meth) acrylamide, Nn-butoxymethylacrylamide, N-isobutoxymethylacrylamide, N-methoxymethylacrylamide, Nt-butylacrylamide, N, N′-methylenebisacrylamide, and the like are preferable. Among them, N-hydroxymethyl (meth) acrylamide and N-hydroxyethyl (meth) acrylamide are preferable from the viewpoint of improving adhesiveness. Amide, (meth) acryloyl morpholine, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, diacetone (meth) acrylamide, and (meth) acrylamide preferred. These (c2-1) components can be used alone or in combination of two or more. As the component (c2-1), a commercially available product or a synthetic product may be used.

  Commercially available products include HEAA (registered trademark), ACMO (registered trademark), DMAPAA (registered trademark), DMAA (registered trademark), NIPAM (registered trademark), DEAA (registered trademark) (all manufactured by KJ Chemicals Corporation), DAAm (above, manufactured by Nippon Kasei Co., Ltd.), NBMA, IBMA, NMMA, TBAA, MBAA (above, manufactured by MRC Unitech Co., Ltd.), NMAM (above, manufactured by Miki Riken Kogyo Co., Ltd.) and the like are preferable.

{(C2-2) Functional group-containing monomer which is a (meth) acrylate monomer not having a plurality of radically polymerizable functional groups}
The main agent (A) according to the present invention is a functional group-containing monomer that is a (meth) acrylic ester monomer having no (c2-2) a plurality of radically polymerizable functional groups (hereinafter, also simply referred to as a (c2-2) component). ) May be included.

  The functional group-containing monomer is not particularly limited as long as it is a (meth) acrylate monomer having no plurality of radically polymerizable functional groups. According to a preferred embodiment of the present invention, the component (c2-2) Is a (meth) acrylate monomer having a hydroxyl group, an acyl group or an epoxy group.

  When a compound can be the component (c2-2) and can also be the component (c1) or the component (c2-1), it is classified as the component (c1) or the component (c2-1). Shall be.

  The component (c2-2) is combined with the component (c2-1) and included as a constituent unit of the polymer contained in the cured pressure-sensitive adhesive layer. Thereby, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention has an effect of improving the adhesiveness, and the intended effect of the present invention can be exhibited more efficiently.

  The (meth) acrylate monomer having a hydroxyl group, an acyl group or an epoxy group is typically represented by the following formula (3):

Indicated by

Here, in the above equation (3),
R ₅ is a hydrogen atom or a methyl group,
R ₆ is a divalent organic group or a single bond,
R ₇ is a hydroxyl group, an acyl group or an epoxy group.

  The number of carbon atoms of the acyl group is not particularly limited, but is preferably 1 or more and 18 or less, more preferably 1 or more and 6 or less. The acyl group includes an acetoacetoxy group.

  Here, the divalent organic group is not particularly limited, but an alkylene group having 1 to 10 carbon atoms is preferable. Examples of the alkylene group having 1 to 10 carbon atoms include the same as described above. Further, the alkylene group or the acyl group substitutes at least one alkyl group having 1 to 8 carbon atoms, a phenoxyalkyl group (carbon number of the alkyl group: 1 to 8 carbon atoms), a phenyl group or a cyclohexyl group. It may have as a group. The alkyl group having 1 to 8 carbon atoms can be appropriately selected from the above.

  From the above, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, acetoacetoxyethyl (meth) acrylate, 2-hydroxymethyl (meth) acrylate, 2-hydroxypropyl (meth) ) Acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 1,4-cyclohexanedimethanol (meth) monoacrylate and the like are preferred. Among them, from the viewpoint of adhesiveness, 4-hydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, acetoacetoxyethyl (meth) acrylate, and the like are preferable. These components (c2-2) can be used alone or in combination of two or more. As the component (c2-2), a commercially available product or a synthetic product may be used.

  Commercially available products include 2HEA (above, manufactured by Nippon Shokubai Co., Ltd.), 4HBA, CHDMMA (above, manufactured by Nippon Kasei Co., Ltd.), light ester HOA (N), light ester HOP-A (N), and light acrylate HOB-A. , Epoxy ester M-600A (manufactured by Kyoeisha Chemical Co., Ltd.), GMA (manufactured by Mitsubishi Gas Chemical Co., Ltd.), AAEM (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and the like are preferable.

<< (c2-3) Macromonomer having polymerizable functional group >>
The main agent (A) according to the present invention may contain (c2-3) a macromonomer having a polymerizable functional group (hereinafter, also referred to as a (c2-3) component). The component (c2-3) is a high-molecular-weight monomer having a polymerizable functional group (unsaturated group), and has a polymer chain portion and a polymerizable functional group portion.

  By including a polymer polymerized (cured) using such a monomer in the pressure-sensitive adhesive layer, bending resistance (bending resistance) is improved. The mechanism is considered to differ depending on the glass transition temperature of the polymer chain portion of the macromonomer. Specifically, when the glass transition temperature of the polymer chain portion is high, the polymer chain portion forms a hard segment in the pressure-sensitive adhesive layer, thereby generating a cohesive force in the pressure-sensitive adhesive layer. Thereby, it is considered that the adhesive strength to the base material is increased and the bending resistance is improved. On the other hand, when the glass transition temperature of the polymer chain portion of the macromonomer is low, it is considered that the pressure-sensitive adhesive layer becomes flexible and the followability to the base material is enhanced, so that the bending resistance is improved. Note that the above mechanism is presumed, and the present invention is not limited to the above mechanism at all.

  As the polymerizable functional group of the component (c2-3), a group having an ethylenically unsaturated double bond (ethylenically unsaturated group) is preferable. Specifically, it is preferably at least one selected from the group consisting of a vinyl group, an allyl group, a (meth) acryloyl group, and a propenyl group. The polymerizable group is preferably present at the terminal of the macromonomer, and more preferably present at only one terminal of the macromonomer from the viewpoint of stability during polymerization. However, the polymerizable group may be present as a side chain of the macromonomer, or may be present at both ends of the macromonomer chain.

  The polymer chain portion of the component (c2-3) includes methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, stearyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth). A (co) polymer having a repeating unit derived from acrylate, t-butyl (meth) acrylate, styrene, acrylonitrile, hydroxy (meth) acrylate, ethylhexyl acrylate, dimethylsiloxane or the like as a main constituent unit is preferable. These polymer chain portions may be composed of a single repeating unit, or may be composed of a plurality of repeating units. Further, when the polymer chain is a copolymer composed of a plurality of repeating units, the repeating form is not limited, and may be any of an alternating copolymer, a random copolymer, and a block copolymer.

  The component (c2-3) is typically represented by the following formula (4):

Indicated by

Here, in the above formula (4), R ₁₂ represents a hydrogen atom or a methyl group, and X ₁ represents a single bond or a divalent bonding group.

  Examples of the divalent linking group include a linear, branched or cyclic alkylene group, an aralkylene group, and an arylene group. These may further have a substituent such as a hydroxy group and a cyano group. The number of carbon atoms of the alkylene group is preferably 1 or more and 10 or less, more preferably 1 or more and 4 or less. Examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, an octylene group, and a decylene group. Among these, a methylene group, an ethylene group, a propylene group and the like are preferable. The aralkylene group preferably has 7 to 13 carbon atoms. Examples of the aralkylene group include a benzylidene group and a cinnamylidene group. The arylene group preferably has 6 to 12 carbon atoms. Examples of the arylene group include a phenylene group, a cumenylene group, a mesitylene group, a tolylene group, and a xylylene group. Among these, a phenylene group is preferred.

During divalent linking group, _{further, -NR 2 -, - COO -} , - OCO -, - O -, - S -, - SO 2 NH -, - NHSO 2 -, - NHCOO -, - OCONH- Alternatively, a group derived from a heterocycle may be interposed as a bonding group. R ₂ is a hydrogen atom or an alkyl group such as a methyl group, an ethyl group, and a propyl group.

In the above formula (4), _{X 2} is methyl (meth) acrylate, ethyl (meth) acrylate, n- butyl (meth) acrylate, stearyl (meth) acrylate, n- butyl (meth) acrylate, isobutyl (meth A) a polymer obtained by homopolymerizing or copolymerizing one or two or more monomers selected from acrylate, t-butyl (meth) acrylate, styrene, acrylonitrile, hydroxy (meth) acrylate, and ethylhexyl acrylate; Represents a polysiloxane (polyorganosiloxane) bonded to an atom. Among them, X ₂ is methyl (meth) acrylate, styrene, n- butyl (meth) acrylate, isobutyl (meth) acrylate homopolymer is not formed by polymers, acrylonitrile and made by copolymerizing styrene polymers or polyorganosiloxanes Preferably, there is. Furthermore, from the viewpoint of durability at high temperatures, X ₂ is particularly preferably a polymer obtained by homopolymerizing methyl (meth) acrylate, styrene, or isobutyl (meth) acrylate or a polymer obtained by copolymerizing acrylonitrile and styrene. . Alternatively, from the viewpoint of bending resistance at low temperatures, X ₂ is a polyorganosiloxane is preferred polydimethylsiloxane is particularly preferred. As long as the performance of the pressure-sensitive adhesive is not affected, a part of the methyl group of the polydimethylsiloxane may be substituted with a hydrogen atom or an organic group other than the methyl group (such as an ethyl group or a phenyl group).

  The polydimethylsiloxane can be obtained by hydrolyzing and condensing dimethyldialkoxysilane such as dimethyldimethoxysilane and dimethyldiethoxysilane. At this time, an organic group other than a methyl group can be introduced into polydimethylsiloxane by using an alkoxysilane having an organic group other than a methyl group (for example, diethyldiethoxysilane or the like) in combination. Further, in addition to the dialkoxy-type silane compound, a small amount of a trialkoxy-type silane compound may be added.

  The number average molecular weight (Mn) of the component (c2-3) is preferably in the range of 2,000 to 20,000, more preferably in the range of 2,000 to 10,000, and more preferably in the range of 4,000 to 8,000. It is more preferred that there be. When the number average molecular weight (Mn) is 2,000 or more, the performance of the pressure-sensitive adhesive can be improved even when the addition amount of the component (c2-3) in synthesizing the copolymer (C) is small. . On the other hand, when it is 20,000 or less, the viscosity of the pressure-sensitive adhesive is low and the workability is good. The value of the number average molecular weight (Mn) can be controlled by appropriately selecting the amounts of a chain transfer agent, a polymerization initiator, and the like to be added to the polymerization system. In the present invention, as the number average molecular weight (Mn) of the macromonomer, a value in terms of polystyrene measured by a GPC (gel permeation chromatography) method is adopted.

  As the component (c2-3), a commercially available product or a synthesized product may be used. When synthesizing the component (c2-3), there is no particular limitation on the synthesis method. For example, (1) a polymer chain (living polymer anion) constituting a macromonomer is produced by living anion polymerization, and methacrylic acid chloride or the like is added thereto. (2) a radically polymerizable monomer such as methyl methacrylate is polymerized in the presence of a chain transfer agent such as mercaptoacetic acid to obtain an oligomer having a terminal carboxyl group, which is then glycidyl methacrylate. (3) a radically polymerizable monomer such as methyl methacrylate is polymerized in the presence of an azo-based polymerization initiator having a carboxyl group to obtain an oligomer having a terminal carboxyl group, and then glycidyl methacrylate Any method such as a method for converting into a macromonomer can be used.

By producing a macromonomer by using the method as described above, as the divalent linking group represented by X ₁ in the above formula (4), for example, it is introduced groups as shown below.

  As a commercially available product of the component (c2-3), for example, a macromonomer having a methacryl group at the end and a polymethyl methacrylate (PMMA) at the terminal (product name: 45% AA-6 (AA-6S)) , AA-6; manufactured by Toagosei Co., Ltd.), a macromonomer having a polymer chain portion of polystyrene (product name: AS-6S, AS-6; manufactured by Toagosei Co., Ltd.), and a polymer chain portion of styrene / acrylonitrile. A macromonomer (product name: AN-6S; manufactured by Toagosei Co., Ltd.) which is a polymer, a macromonomer having a polymer chain portion of polybutyl acrylate (product name: AB-6; manufactured by Toagosei Co., Ltd.), and a polymer chain portion Macroisomers (product name: AW-6S; manufactured by Toagosei Co., Ltd.), which is polyisobutyl methacrylate Hexane at a macromonomer (product name: AK-5; manufactured by Toagosei Co., Ltd.) and the like can be used. These macromonomers may be used alone or in combination of two or more.

{(C2-4) Component (c1), component (c2-1), component (c2-2), and (meth) acrylate monomer other than component (c2-3)}
The main component (A) according to the present invention comprises (c1) component, (c2-1) component, (c2-2) component, and (c2-4) (meth) acrylate monomer other than component (c2-3). (Hereinafter, also simply referred to as component (c2-4)).

  The component (c2-4) is not particularly limited as long as it is a (meth) acrylate monomer other than the component (c1), the component (c2-1), the component (c2-2), and the component (c2-3). However, for example, a (meth) acrylate monomer having an alkoxyalkyl group or an alkylene oxide group is preferable.

  As described above, in a preferred embodiment of the present invention, (meth) acrylic acid ester monomers other than the component (c1), the component (c2-1), the component (c2-2) and the component (c2-3) ((c2- 4) Component) is preferably a (meth) acrylate monomer having an alkoxyalkyl group or an alkylene oxide group.

  The (meth) acrylate monomer having an alkoxyalkyl group or an alkylene oxide group is not particularly limited as long as it has an alkoxyalkyl group or an alkylene oxide structure in a (meth) acrylate ester molecule. It is considered that such components are contained in the constituent units of the copolymer contained in the pressure-sensitive adhesive layer, and have an effect of improving the adhesiveness and the durability. In addition, since the polymer contained in the pressure-sensitive adhesive layer after curing has the structural unit derived from the component (c2-4), it is possible to impart flexural resistance at low temperatures, and to reduce the adhesiveness at low temperatures without lowering the adhesiveness. Bending resistance can be ensured. However, in the present invention, when it has a structural unit derived from the component (c2-1), it may or may not have a structural unit derived from the component (c2-4). The desired effect can be achieved.

  The number of carbon atoms of the alkoxy moiety in the alkoxyalkyl group is not particularly limited, but is preferably 1 or more and 6 or less from the viewpoint of improving adhesiveness and durability, and efficiently exhibiting the intended effect of the present invention. Is preferable, and it is more preferable that it has 1 to 4 carbon atoms. As the alkoxy moiety having 1 to 6 carbon atoms, the specific examples listed above are preferable.

  The number of carbon atoms in the alkyl portion of the alkoxyalkyl group is not particularly limited. However, from the viewpoint of efficiently improving the intended effect of the present invention, the balance between the improvement in adhesion and the improvement in durability, and the number of carbon atoms of 1 or more. It is preferably 8 or less. Specific examples of the alkyl moiety having 1 to 8 carbon atoms can also be appropriately selected from the specific examples listed above.

  In the alkylene oxide group, the number of carbon atoms in the alkylene portion is not particularly limited. However, from the viewpoint of improving the adhesiveness and durability, and efficiently exhibiting the intended effect of the present invention, the number of carbon atoms is 1 or more and 4 or less. Is preferable, and the number of carbon atoms is preferably 1 or more and 3 or less.

  The (meth) acrylate monomer having an alkoxyalkyl group or an alkylene oxide group is typically represented by the following formula (5):

Indicated by

Here, in the above equation (5),
R ₃ is a hydrogen atom or a methyl group,
R ₄ is an alkoxyalkyl group or — (A—O) _n —Q.

  Here, as the alkoxyalkyl group, a methoxyethyl group, an ethoxymethyl group, an ethoxyethyl group, a propoxyethyl group, a butoxyethyl group, a methoxypropyl group, a methoxybutyl group, and a 2-ethylhexyloxyalkyl group are preferable.

  A is a methylene group, an ethylene group, a propylene group or a butylene group, and n is preferably 1 or more and 20 or less, more preferably 1 or more and 15 or less.

  Q is an alkyl group. Such an alkyl group may be linear or branched, and has preferably 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms, and still more preferably 1 to 3 carbon atoms. It is. As specific examples of such an alkyl group, those listed above are preferable, and a methyl group, an ethyl group or a propyl group is particularly preferable.

  From the above, methoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, methoxypropyl (meth) acrylate, methoxybutyl (meth) Acrylates: ethoxydiethylene glycol (meth) acrylate, ethoxy-triethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxydiethylene glycol (meth) acrylate, propoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate , 2-ethylhexyloxydidiethylene glycol (meth) acrylate, methoxypolyethylene glycol Call (meth) acrylate, methoxy dipropylene glycol (meth) acrylate.

  Among these, from the viewpoint of improving the adhesiveness and durability and efficiently exhibiting the intended effects of the present invention, in particular, methoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate, ethoxyethyl (meth) acrylate, Propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, methoxypropyl (meth) acrylate, methoxybutyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 2-ethylhexyloxydiethylene glycol ( (Meth) acrylate and methoxypolyethylene glycol (meth) acrylate are more preferred. These components (c2-4) can be used alone or in combination of two or more. As the component (c2-4), a commercially available product or a synthesized product may be used.

  Commercial products of the component (c2-4) include AME (all manufactured by Nippon Shokubai Co., Ltd.), Light Acrylate EC-A, Light Acrylate MTG-A, Light Acrylate EHDG-AT, Light Acrylate 130A, and Light Acrylate DPM-A. (Manufactured by Kyoeisha Chemical Co., Ltd.), Viscoat # 190, 2-MTA, MPE400A, MPE550A (manufactured by Osaka Organic Chemical Industry Co., Ltd.), AM-90G, AM-130G, (above, Shin-Nakamura Chemical Co., Ltd.) Is preferred.

<< Content of each component in the form of the above (1) >>
The content of the component (c1) is defined assuming that the total amount of the component (c1), the component (c2-1), the component (c2-2), the component (c2-3), and the component (c2-4) is 100% by mass. , 9.9 mass% or more and 99.9 mass% or less. When the content is 9.9% by mass or more, bending resistance at high temperature and high temperature and high humidity is excellent, and adhesive strength is improved. On the other hand, if the content is 99.9% by mass or less, various durability is excellent, bending resistance at high temperature is excellent, and adhesive strength at high temperature is improved. Further, the content of the component (c1) is more preferably more than 9.9% by mass and less than 99.9% by mass, and further preferably 10% by mass, from the viewpoint that the intended effect of the present invention is more exerted. % To 99% by mass, more preferably 20% to 98% by mass, particularly preferably 30% to 97% by mass, most preferably 40% to 95% by mass or It is 60% by mass or more and 90% by mass or less.

  The content of the component (c2-1) is 100 mass of the total amount of the component (c1), the component (c2-1), the component (c2-2), the component (c2-3), and the component (c2-4). % Is preferably from 0% by mass to 15% by mass. More preferably, the content is 0.5% by mass or more and 13% by mass or less, and further preferably 0.8% by mass or more and 11% by mass or less from the viewpoints of improving adhesion and ensuring durability.

  The content of the component (c2-2) is 100 mass of the total amount of the component (c1), the component (c2-1), the component (c2-2), the component (c2-3), and the component (c2-4). %, It is preferably 0% by mass or more and less than 20% by mass. From the viewpoint of ensuring sufficient amounts of the component (c1) and the component (c2-1), the content of the component (c2-2) is preferably less than 20% by mass. Further, the content of the component (c2-2) is preferably more than 0% by mass, more preferably 5% by mass or more and 19% by mass or less, from the viewpoint of exhibiting the intended effect of the present invention. And more preferably 5% by mass or more and 18% by mass or less, particularly preferably 5% by mass or more and 17% by mass or less.

  The content of the component (c2-3) is 100 mass of the total amount of the component (c1), the component (c2-1), the component (c2-2), the component (c2-3), and the component (c2-4). % Is preferably from 0% by mass to 15% by mass. When the content is within this range, excellent bending resistance (bending resistance) is obtained. Further, the upper limit of the content is more preferably 8% by mass or less, further preferably 5% by mass or less. In addition, the lower limit of the content is more preferably 0.5% by mass or more, and further preferably 0.8% by mass or more, from the viewpoint of obtaining the effect of the addition of the component (c2-3).

  The content of the component (c2-4) is 100% by mass based on the total amount of the component (c1), the component (c2-1), the component (c2-2), the component (c2-3), and the component (c2-4). Is preferably 0% by mass or more and 90% by mass or less. Here, even if the content of the component (c2-4) is sufficiently small, for example, less than 5% by mass, by including the component (c2-1), the intended effect of the present invention can be sufficiently improved. Can be played. The content of the component (c2-4) is more preferably 0% by mass or more and 55% by mass or less, and still more preferably 0% by mass or more and 50% by mass, from the viewpoint of exhibiting the intended effect of the present invention. %, Particularly preferably from 0% by mass to 45% by mass. If the content exceeds 90% by mass, gelation may occur, and the function as an adhesive may not be achieved.

<< Form of the above (2) >>
As one mode according to the present invention, the main agent (A) has a component (c1), a component (c2), and a (meth) acrylate ester having a structural unit derived from the component (c1) and a structural unit derived from the component (c2). A form composed of the copolymer (C) (hereinafter, also simply referred to as the copolymer (C)) (a form in which the curable compound is composed of a monomer and a polymer) is exemplified. This embodiment is a so-called polymer in which, among the raw material monomers of the copolymer (C), the components (c1) and (c2), which are unreacted raw material monomers, serve as a solvent for dissolving the copolymer (C). It is in the form of a syrup.

  Suitable content of component (c1), component (c2) (component (c2-1), component (c2-2), component (c2-3), and component (c2-4)) in the form (2). The amount is the same as the preferred content described in the section of {Content of Each Component in the Mode (1)}, and thus the description is omitted here.

  In addition, the preferred content of each structural unit of the copolymer (C) contained in the form (2) is determined by the content of each component ((( Suitable contents of the components (c1) and (c2) are applied as they are.

  That is, the copolymer (C) contained in the form of (2) has an amide group of 9.9% by mass or more and 99.9% by mass or less of the structural unit derived from the alkyl (meth) acrylate monomer (c1). Structural unit derived from (meth) acrylic monomer (c2-1) 0 mass% to 15 mass%, and a functional group-containing monomer (c2-2) which is a (meth) acrylate monomer having no plurality of radically polymerizable functional groups. ) -Derived structural unit from 0% by mass to less than 20% by mass, a structural unit derived from a macromonomer (c2-3) having a polymerizable functional group from 0% by mass to 15% by mass, and the component (c1), (c2- 1) Structural units derived from the (meth) acrylate monomer (c2-4) other than the component, the component (c2-2), and the component (c2-3), from 0% by mass to 90% by mass. The following (however, the total amount of the structural units derived from the components (c1), (c2-1), (c2-2), (c2-3) and (c2-4) is 100% by mass). It is preferred to have.

  In the embodiment (2), the content of the copolymer (C) with respect to the total mass of the main agent (A) is preferably from 3% by mass to 25% by mass, more preferably from 5% by mass to 20% by mass. The content of the copolymer (C) can be controlled, for example, by controlling the polymerization rate in a bulk polymerization method using a photopolymerization initiator described below.

<< Form of the above (3) >>
One embodiment according to the present invention includes an embodiment in which the main agent (A) is composed of the copolymer (C) (a configuration in which the curable compound is composed of only a polymer).

  The preferred content of each structural unit of the copolymer (C) contained in the form (3) is determined by the content of each component ((c1) described in the section “Content of each component in the form (1) above). The suitable content of the component (component (c2)) is applied as it is.

  That is, the copolymer (C) contained in the form (3) has an amide group of 9.9% by mass to 99.9% by mass of a structural unit derived from the alkyl (meth) acrylate monomer (c1). Structural unit derived from (meth) acrylic monomer (c2-1) 0 mass% to 15 mass%, and a functional group-containing monomer (c2-2) which is a (meth) acrylate monomer having no plurality of radically polymerizable functional groups. ) -Derived structural unit from 0% by mass to less than 20% by mass, a structural unit derived from a macromonomer (c2-3) having a polymerizable functional group from 0% by mass to 15% by mass, and the component (c1), (c2- 1) Structural units derived from the (meth) acrylate monomer (c2-4) other than the component, the component (c2-2), and the component (c2-3), from 0% by mass to 90% by mass. The following (however, the total amount of the structural units derived from the components (c1), (c2-1), (c2-2), (c2-3) and (c2-4) is 100% by mass). It is preferred to have.

[Production of (meth) acrylate copolymer (C)]
In the above embodiments (2) and (3), the method for producing the (meth) acrylate copolymer (C) that can be contained in the main agent (A) is not particularly limited, and a solution using a polymerization initiator Conventionally known methods such as a polymerization method, a bulk polymerization method, an emulsion polymerization method, a suspension polymerization method, a reversed phase suspension polymerization method, a thin film polymerization method, and a spray polymerization method can be used. Examples of the polymerization control method include an adiabatic polymerization method, a temperature-controlled polymerization method, and an isothermal polymerization method. As the polymerization initiator, any of a thermal polymerization initiator and a photopolymerization initiator may be used. In addition to or in addition to the method of initiating polymerization with a polymerization initiator, a method of initiating polymerization by irradiation with an active energy ray such as radiation, an electron beam, or ultraviolet light can also be employed. Among them, a solution polymerization method using a thermal polymerization initiator or a bulk polymerization method using a photopolymerization initiator is more preferable because the molecular weight can be easily adjusted and impurities can be reduced.

  As a solution polymerization method using a thermal polymerization initiator, for example, using ethyl acetate, toluene, methyl ethyl ketone, or the like as a solvent, the thermal polymerization initiator is used based on 100 parts by mass of the total amount of the raw material monomers of the copolymer (C). Is added in an amount of preferably 0.01 to 0.50 parts by mass under a nitrogen atmosphere, for example, at a reaction temperature of 40 to 90 ° C. (or 60 to 90 ° C.) for 3 to 10 hours. A method for causing the reaction is mentioned.

  Examples of the thermal polymerization initiator include 2,2-azobisisobutyronitrile (AIBN), 2,2′-azobis (2-methylbutyronitrile), azobiscyanovaleric acid, and 2,2′-azobis ( 4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2.4-dimethylvaleronitrile), dimethyl 2,2'-azobis (2-methylpropionate), 2,2'- Azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis [N- (2-propenyl) -2-methylpropionamide], 2,2 '-Azobis (N-butyl-2-methylpropionamide), 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride, 2,2'- Zobis [2- (2-imidazolin-2-yl) propane] disulfate dihydrate, 2,2'-azobis (2-methylpropionamidine) dihydrochloride, 2,2'-azobis [N- (2-carboxyethyl)- 2-methylpropionamidine] hydrate, 2,2′-azobis [2- (2-imidazolin-2-yl) propane], 2,2′-azobis (1-imino-1-pyrrolidino-2-methylpropane) Azo compounds such as dihydrochloride and 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide]; tert-butylperoxypivalate, tert-butylperoxybenzoate, tert-butylperoxy -2-ethylhexanoate, di-tert-butyl peroxide, Organic peroxides such as men hydroperoxide, benzoyl peroxide and tert-butyl hydroperoxide; and inorganic peroxides such as hydrogen peroxide, ammonium persulfate, potassium persulfate and sodium persulfate. These thermal polymerization initiators can be used alone or in combination of two or more. According to this method, the main agent (A) composed of the copolymer (C) can be obtained (the above-mentioned (3)).

  The bulk polymerization method using a photopolymerization initiator is not particularly limited. For example, a raw material monomer of the copolymer (C) and a photopolymerization initiator are added, and the reaction initiation temperature is set to 20 ° C. under a nitrogen atmosphere. Irradiate with active energy rays at 28 ° C or lower, and at the stage when the temperature in the reaction system rises from 5 ° C to 15 ° C from the reaction start temperature, stop the reaction by introducing air into the reaction system, etc. A method for obtaining the copolymer (C) is exemplified. At this time, it is not necessary to react all of the raw material monomers to be used, and the reaction may be stopped when the desired weight average molecular weight is reached. Since the unreacted raw material monomers (c1) and (c2) serve as a solvent for dissolving the copolymer (C), according to this method, the components (c1), (c2) and The main ingredient (A) (polymer syrup) composed of the union (C) can be obtained (the form of the above (2)).

Examples of the active energy rays used in the bulk polymerization method include, for example, ultraviolet rays, laser rays, α rays, β rays, γ rays, X rays, and electron beams, but have good controllability and handleability, and cost. In view of the above, ultraviolet rays are preferably used. More preferably, ultraviolet light having a wavelength of 200 nm or more and 400 nm or less is used. Ultraviolet rays can be emitted using a light source such as a high-pressure mercury lamp, a microwave excitation lamp, a chemical lamp, and a black light. Illuminance is preferably 3.2 mW / cm ² or more and 5.6 mW / cm ² or less.

  Examples of the photopolymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethylketal, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1- (4-isopropylphenyl) -2-hydroxy- 2-methylpropan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one and the like Benzophenones such as benzophenone, 4-chlorobenzophenone and 4,4'-diaminobenzophenone; benzoin ethers such as benzoin propyl ether and benzoin ethyl ether; thioxanthones such as 4-isopropylthioxanthone; 1-hydroxy Cyclohexylphenylke Down, a xanthone, fluorenone, camphor quinone, benzaldehyde, anthraquinone, and the like. These photopolymerization initiators can be used alone or in combination of two or more.

  Commercially available photopolymerization initiators may be used. Examples of commercially available products include Irgacure (registered trademark) 184, 819, 907, 651, 1700, 1800, 819, 369, 261 and Darocur (registered trademark) TPO. , Darocure (registered trademark) 1173 (above, manufactured by BASF Japan KK), Ezacure (registered trademark) KIP150, TZT (above, manufactured by DKSH Japan KK), Kayacure (registered trademark) BMS, DMBI (all, manufactured by Nippon Kayaku Co., Ltd.) Manufactured by a company).

  The amount of the photopolymerization initiator used is preferably 0.001 part by mass or more and 1 part by mass or less, more preferably 0.003 part by mass or more, based on 100 parts by mass of the total amount of the raw material monomers of the copolymer (C). It is 0.5 parts by mass or less.

  In addition, in synthesizing the copolymer (C), a chain transfer agent can be used to adjust the molecular weight. For example, methyl mercaptan, t-butyl mercaptan, decyl mercaptan, benzyl mercaptan, lauryl mercaptan, stearyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, mercaptoacetic acid, mercaptopropionic acid and esters thereof, 2-ethylhexylthioglycol, thioglycol Mercaptans such as octyl acid; alcohols such as methanol, ethanol, propanol, n-butanol, isopropanol, t-butanol, hexanol, benzyl alcohol and allyl alcohol; halogenated hydrocarbons such as chloroethane, fluoroethane and trichloroethylene; acetone , Methyl ethyl ketone, cyclohexanone, acetophenone, acetaldehyde, propionaldehyde n- butyraldehyde, furfural, carbonyls, such as benzaldehyde; methyl-4-cyclohexene-1,2-dicarboxylic acid anhydride, such as α- methyl styrene. These may be used alone or in combination of two or more.

  In the present invention, the weight average molecular weight (Mw) of the copolymer (C) is preferably from 1,000,000 to 3.5,000,000, more preferably from 1.2,000,000 to 3.2,000,000. When the weight average molecular weight is 1,000,000 or more, durability is excellent, peeling and floating can be suppressed, and adhesiveness is improved. When the viscosity is 3.5 million or less, the viscosity of the copolymer solution becomes appropriate and workability such as coatability is improved.

[Additive (B)]
The pressure-sensitive adhesive composition of the present invention has at least one selected from the group consisting of a trisubstituted aromatic compound, a triaryl phosphate, an aliphatic tricarboxylic acid ester, an alicyclic tricarboxylic acid ester, and a polyoxyalkylene sorbitan fatty acid ester. It contains seed additives (B). It can be said that these additives have three or more functional groups extending in geometrically different directions, and can be said to have a bulky (bulky) structure rather than a mere planar structure. Therefore, the additive (B) has an effect of restraining not only the planar direction but also the relatively soft pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition in the thickness direction. By such an action, a pressure-sensitive adhesive layer having an excellent balance between adhesive strength and bending resistance that hardly causes peeling or floating even when bent over the entire temperature range where use is assumed is provided. It is believed that a pressure-sensitive adhesive composition that can be formed can be obtained.

  Specific examples of the additive (B) include, for example, tri-n-butyl trimellitate (tri-n-butyl trimellitate) and tri-n-hexyl trimellitate (tri-n-hexyl trimellitate). Tetrate), tri-n-octyl trimellitate (tri-n-octyl trimellitate), tris (2-ethylhexyl) trimellitate (tri-2-ethylhexyl trimellitate), triisooctyl trimellitate, tri Tri-n-nonyl melitate, triisononyl trimellitate, triisodecyl trimellitate (triisodecyl trimellitate), tri-n-octyl trimesate, tris (2-ethylhexyl) trimesate, tri-n-nonyl trimesate Etc .; triphenyl phosphate, tricresyl phosphate Tri-p-cresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, cresyl dixylenyl phosphate, dicresyl xylenyl phosphate, triisopropyl phenyl phosphate, α-naphthyl diphenyl phosphate, di- Triaryl phosphates such as α-naphthylphenyl phosphate, β-naphthyldiphenylphosphate, di-β-naphthylphenylphosphate; trimethyl citrate, triethyl citrate, tri-n-propyl citrate, triisopropyl citrate, citric acid Tri-n-butyl, tri-sec-butyl citrate, tri-t-butyl citrate, tri-n-hexyl citrate, tri-n-heptyl citrate, triisoamyl citrate, quencher Tri-3-methylpentyl citrate, Tri-2-methylpentyl citrate, Tri-1-methylpentyl citrate, Tri-n-octyl citrate, Tri-n-nonyl citrate, Tri-n-decyl citrate , Tri-n-dodecyl citrate, tristearyl citrate, triphenyl citrate, trimethyl isocitrate, trimethyl isocitrate, tri-n-propyl isocitrate, triisopropyl isocitrate, tri-n-butyl isocitrate, isocitrate Tri-sec-butyl, tri-tert-butyl isocitrate, tri-n-hexyl isocitrate, tri-n-heptyl isocitrate, triisoamyl isocitrate, tri-3-methylpentyl isocitrate, tri-2 isocitrate -Methylpentyl, tri-1-methylpentyl isocitrate Tri-n-octyl isocitrate, tri-n-nonyl isocitrate, tri-n-decyl isocitrate, tri-n-dodecyl isocitrate, tristearyl isocitrate, triphenyl isocitrate, triethyl acetylcitrate, acetylcitrate Aliphatic tricarboxylic acid esters such as tri-n-butyl and acetyl tri (2-ethylhexyl) citrate; cyclopentanone-2,3,5-tricarboxylic acid trimethyl ester, cyclopentanone-2,4,4-tricarboxylic acid Trimethyl ester, cyclohexane-1,2,3-tricarboxylic acid tri (2-ethylhexyl) ester, cyclohexane-1,2,4-tricarboxylic acid triisononyl ester, 4-cyclohexene-1,2,3-tricarboxylic acid tri ( 2-ethylhexyl) S And cycloaliphatic tricarboxylic esters such as 5-cyclohexene-1,2,4-tricarboxylic acid triisononyl ester; polyoxyethylene sorbitan laurate ester, polyoxyethylene sorbitan palmitate ester, polyoxyethylene sorbitan oleate ester And polyoxyalkylene sorbitan fatty acid esters. These additives (B) can be used alone or in combination of two or more. Further, as the additive (B), a commercially available product or a synthetic product may be used.

  Examples of commercially available additives (B) include, for example, CDP, TXP (all, manufactured by Daihachi Chemical Industry Co., Ltd.), T-10 (all, manufactured by Kao Corporation), TOTM, TOTM-NB (all, J. Plus Co., Ltd.). From the viewpoint that the effects of the present invention can be exhibited more efficiently, the additive (B) preferably has three or more functional groups having a molecular weight of 78 or more. Here, the functional group in the trisubstituted aromatic compound refers to a substituent directly bonded to an aromatic ring. In triaryl phosphate, it refers to an aryloxy group directly bonded to a phosphorus atom. In aliphatic tricarboxylic acid esters, it refers to a functional group directly bonded to the most substituted carbon atom. In the alicyclic tricarboxylic acid ester, it refers to an ester group directly bonded to an aliphatic ring. As for polyoxyalkylene sorbitan fatty acid ester, it refers to a functional group directly bonded to the sorbitan skeleton.

  Therefore, as a functional group having a molecular weight of 78 or more, n-propyloxycarbonyl group, isopropyloxycarbonyl group, n-butyloxycarbonyl group, isobutyloxycarbonyl group, sec-butyloxycarbonyl group, tert-butyloxycarbonyl group, n -Pentyloxycarbonyl group, isopentyloxycarbonyl group, sec-pentyloxycarbonyl group, tert-pentyloxycarbonyl group, n-hexyloxycarbonyl group, n-heptyloxycarbonyl group, n-octyloxycarbonyl group, isooctyloxy Carbonyl group, sec-octyloxycarbonyl group, tert-octyloxycarbonyl group, 2-ethylhexyloxycarbonyl group, n-nonyloxycarbonyl group, isononyloxycarbonyl Group, n-decyloxycarbonyl group, isodecyloxycarbonyl group, n-dodecyloxycarbonyl group, stearyloxycarbonyl group, 3-methylpentyloxycarbonyl group, 2-methylpentyloxycarbonyl group, 1-methylpentyloxycarbonyl group Alkyloxycarbonyl groups such as phenoxycarbonyl group, cresyloxycarbonyl group, xylyloxycarbonyl group, naphthoxycarbonyl group, anthryloxycarbonyl group, phenanthryloxycarbonyl group and the like; phenoxy group, Aryloxy groups such as crezoxy group, xylenoxy group, trimethylphenoxy group, isopropylphenoxy group, 4-t-butylphenoxy group, naphthoxy group and biphenyloxy group; Acyloxy groups such as silyl groups, butyryloxy groups, isobutyryloxy groups, valeryloxy groups, isovaleryloxy groups, pivaloyloxy groups, caproyloxy groups, lauroyloxy groups, stearoyloxy groups, benzoyloxy groups; repeating polyoxyalkylene units A polyoxyalkylene group having a number of 2 or more;

  From the above, preferred additives (B) include tri-n-propyl trimellitate, tri-isopropyl trimellitate, tri-n-butyl trimellitate, tri-n-pentyl trimellitate, and tri-n-pentyl trimellitate. -N-hexyl (tri-n-hexyl trimellitate), tri-n-octyl trimellitate (tri-n-octyl trimellitate), tris (2-ethylhexyl) trimellitate (tri-2-ethylhexyl trimellitate) (Melitate), triisooctyl trimellitate, tri-n-nonyl trimellitate, triisononyl trimellitate, triisodecyl trimellitate (triisodecyl trimellitate), tri-n-octyl trimesate, tris trimesate ( 2-ethylhexyl), tri-n-nonyl trimesate, trif Nyl phosphate, tricresyl phosphate, tri-p-cresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, dicresyl phenyl phosphate, cresyl dixylenyl phosphate, dicresyl xylenyl phosphate, triisopropyl phenyl phosphate, α-naphthyl diphenyl phosphate, di-α-naphthyl phenyl phosphate, β-naphthyl diphenyl phosphate, di-β-naphthyl phenyl phosphate, tri-n-butyl citrate, tri-n-pentyl citrate, tri-n-citrate Hexyl, tri-n-heptyl citrate, tri-3-methylpentyl citrate, tri-2-methylpentyl citrate, tri-1-methylpentyl citrate, tri-n-octyl citrate, citrate Tri-n-nonyl acid, tri-n-decyl citrate, tri-n-dodecyl citrate, tristearyl citrate, triphenyl citrate, tri-n-hexyl isocitrate, tri-n-heptyl isocitrate, Tri-3-methylpentyl isocitrate, tri-2-methylpentyl isocitrate, tri-1-methylpentyl isocitrate, tri-n-octyl isocitrate, tri-n-nonyl isocitrate, tri-n-decyl isocitrate Tri-n-dodecyl isocitrate, tristearyl isocitrate, triphenyl isocitrate, tri (2-ethylhexyl) acetyl citrate, tri (2-ethylhexyl) cyclohexane-1,2,3-tricarboxylate, cyclohexane-1 2,2,4-tricarboxylic acid triisononyl ester, 4 Cyclohexene-1,2,3-tricarboxylic acid tri (2-ethylhexyl) ester, 5-cyclohexene-1,2,4-tricarboxylic acid triisononyl ester, polyoxyethylene sorbitan laurate ester, polyoxyethylene sorbitan palmitate ester And polyoxyethylene sorbitan oleate.

  Furthermore, among these additives (B), from the viewpoint that the effect of the present invention can be more easily obtained, the additive is composed of tris (2-ethylhexyl) trimellitate, triisodecyl trimellitate, cresyl diphenyl phosphate, and trixylenyl phosphate. At least one selected from the group is more preferable.

  The freezing point of the additive (B) is preferably lower than −10 ° C., more preferably lower than −20 ° C., and further preferably lower than −25 ° C. When the freezing point is within this range, the bending resistance at high temperatures is excellent.

  The content of the additive (B) in the pressure-sensitive adhesive composition of the present invention is 0.1 parts by mass or more and 8 parts by mass or less based on 100 parts by mass of the main agent (A). When the content of the additive (B) is less than 0.1 part by mass, the bending resistance at low temperatures decreases. On the other hand, when the content of the additive (B) exceeds 8 parts by mass, the bending resistance at high temperatures decreases. The content of the additive (B) is preferably 1 part by mass or more and 7 parts by mass or less, more preferably 4 parts by mass or more and 6 parts by mass or less with respect to 100 parts by mass of the main agent (A).

[Crosslinking agent (D)]
The pressure-sensitive adhesive composition of the present invention preferably further contains a crosslinking agent (D) from the viewpoint that the intended effects of the present invention can be more efficiently achieved. The amount of the crosslinking agent (D) to be added is preferably from 0.001 to 20 parts by mass, more preferably from 0.01 to 5 parts by mass, based on 100 parts by mass of the base material (A). It is at most 0.01 part by mass, more preferably at most 0.01 part by mass but at most 1 part by mass. Within such a range, there is a technical effect of achieving both the adhesion and the bending resistance.

  The type of the crosslinking agent (D) that can be used in the pressure-sensitive adhesive composition of the present invention is not particularly limited, and isocyanate compounds, carbodiimide compounds, oxazoline compounds, epoxy compounds, polyfunctional acrylate monomers, peroxides, and titanium cups It is preferably at least one selected from the group consisting of a ring agent, a zirconium compound, an aluminum chelate compound and a thermal acid generator. In particular, when the crosslinking agent (D) is an isocyanate compound, a carbodiimide compound, an oxazoline compound, an epoxy compound (excluding cases corresponding to the above components (c1) and (c2)), a polyfunctional acrylate monomer ((c1 ), And at least one selected from the group consisting of peroxides (excluding the case corresponding to the component (c2)) and peroxides. Further, from the viewpoint of adhesiveness and durability, the isocyanate compound and the peroxide are preferable. More preferably, it is at least one of oxides.

  The crosslinking agent (D) according to the present invention includes a crosslinking agent (D) which forms a crosslinking structure by itself (curing agent type), and a crosslinking agent which does not form a crosslinking structure by itself but promotes a crosslinking reaction (curing). Catalyst type). In particular, the latter are peroxides, thermal acid generators and the like.

(Isocyanate compound)
The isocyanate compound suitably used as the crosslinking agent (D) is not particularly limited. For example, triallyl isocyanate, dimer diisocyanate, 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate Isocyanate (2,6-TDI), 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 1,4-phenylene diisocyanate, xylylene diisocyanate Aromatic diisocyanates such as isocyanate (XDI), tetramethylxylidene diisocyanate (TMXDI), tolidine diisocyanate (TODI), and 1,5-naphthalenediisocyanate (NDI); hexamethylene diisocyanate (HDI), trimethylhexa Aliphatic diisocyanates such as methylene diisocyanate (TMHDI), lysine diisocyanate, norbornane diisocyanatomethyl (NBDI); transcyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), H6-XDI (hydrogenated XDI), H12- Alicyclic diisocyanates such as MDI (hydrogenated MDI); carbodiimide-modified diisocyanates of the above-mentioned diisocyanates; and isocyanurate-modified diisocyanates thereof, and one or more of these can be used. Moreover, you may use together with the peroxide mentioned later. Adducts of the above isocyanate compounds and polyol compounds such as trimethylolpropane, and biuret and isocyanurate forms of these isocyanate compounds can also be suitably used.

  As the isocyanate compound, a commercially available product or a synthetic product may be used.

  Commercially available products include, for example, Coronate (registered trademark) L, Coronate (registered trademark) HL, Coronate (registered trademark) HX, Coronate (registered trademark) 2030, Coronate (registered trademark) 2031 (all manufactured by Nippon Polyurethane Industry Co., Ltd.) ), Takenate (registered trademark) D-102, Takenate (registered trademark) D-110N, Takenate (registered trademark) D-200, Takenate (registered trademark) D-202 (all manufactured by Mitsui Chemicals, Inc.), Duranate (registered) Trademark) 24A-100, Duranate (R) TPA-100, Duranate (R) TKA-100, Duranate (R) P301-75E, Duranate (R) E402-90T, Duranate (R) E405-80T. , Duranate (registered trademark) TSE-100, Duranate Nate (registered trademark) D-101, Duranate (registered trademark) D-201 (all manufactured by Asahi Kasei Chemicals Corporation), Sumijur (registered trademark) N-75, N-3200, N-3300 (all manufactured by Sumika Bayer) Urethane Co., Ltd.). Among these, Coronate (registered trademark) L, Coronate (registered trademark) HL, Coronate (registered trademark) HX, Takenate (registered trademark) D-110N, Duranate (registered trademark) 24A-100, and duranate (registered trademark) TPA -100 is preferable, and Coronate (registered trademark) L, Coronate (registered trademark) HX, and Duranate (registered trademark) 24A-100 are more preferable.

(Carbodiimide compound)
The carbodiimide compound suitably used as the crosslinking agent (D) is not particularly limited, and examples thereof include those described in paragraphs “0039” to “0046” of JP-A-2012-246444 or those obtained by appropriately modifying them. Can be

(Oxazoline compound)
The oxazoline compound suitably used as the cross-linking agent (D) is not particularly limited, and includes, for example, those described in paragraph “0037” of JP-A-2015-087539 or those appropriately modified.

(Epoxy compound)
As the epoxy crosslinking agent (epoxy compound), any appropriate epoxy crosslinking agent can be adopted. For example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, tetraglycidyl Xylylenediamine, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether and the like can be used.

  Examples of commercially available products include Tetrad (registered trademark) C and Tetrad (registered trademark) X manufactured by Mitsubishi Gas Chemical Co., Ltd., Adeka Resin (registered trademark) EPU series and Adeka Resin (registered trademark) EPR series manufactured by ADEKA Corporation, and And Celloxide (registered trademark) manufactured by Daicel Corporation. In particular, liquid epoxy resins such as these are preferred because the operation of mixing the adhesive when producing the adhesive layer is facilitated.

(Polyfunctional (meth) acrylate monomer)
The polyfunctional acrylate monomer is a (meth) acrylate monomer having a plurality of radically polymerizable functional groups, and examples thereof include a hydrocarbon-based or hydrocarbon ether-based polyfunctional monomer. The hydrocarbon-based or hydrocarbon-ether-based polyfunctional monomer is a compound obtained by (meth) acrylate-forming a hydroxyl group of a polyhydric alcohol having a main skeleton of a hydrocarbon group having 10 to 100 carbon atoms or a hydrocarbon ether group. Yes, it is preferable in terms of adhesiveness due to crosslinking. Examples of the hydrocarbon group of the polyhydric alcohol include a linear or branched aliphatic hydrocarbon group, an aromatic hydrocarbon group, an alicyclic hydrocarbon group, and a hydrocarbon group obtained by combining these hydrocarbon groups. Examples of the hydrocarbon ether group include those obtained by etherifying the hydrocarbon group. Examples of the polyhydric alcohol having a hydrocarbon ether group as a main skeleton include a compound obtained by adding an alkylene oxide having 2 to 4 carbon atoms to the polyhydric alcohol (addition number: 1 to 30), or a compound having 2 or more carbon atoms. Polyalkylene glycol (addition number 1 or more and 30 or less) obtained from alkylene oxide of 4 or less can be mentioned.

  Specific examples of the hydrocarbon-based bifunctional monomer include, for example, 1,3-butylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, and 1,6-hexanediol di (meth) A) acrylates, di (meth) acrylates of alkylene glycols such as neopentyl glycol di (meth) acrylate; alicyclic carbonizations such as cyclohexane dimethanol di (meth) acrylate and tricyclodecane dimethanol di (meth) acrylate Di (meth) acrylate of a diol compound having a hydrogen group; di (meth) acrylate of a diol compound having an aromatic hydrocarbon group such as bisphenol A di (meth) acrylate;

  Specific examples of the hydrocarbon ether-based bifunctional monomer include, for example, alkoxylated hexanediol di (meth) acrylate, alkoxylated cyclohexane dimethanol di (meth) acrylate, and alkoxylated di (meth) acrylate. Dialkyl (meth) acrylates such as alkoxylated neopentyl glycol di (meth) acrylate and alkoxylated bisphenol A di (meth) acrylate, and di (alkylene glycol or diol compounds described above) to which dialkylene compound is added with alkylene oxide. (Meth) acrylate and the like. Specific examples of the hydrocarbon ether-based bifunctional monomer include diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, Examples include poly (alkylene glycol) di (meth) acrylates such as tripropylene glycol di (meth) acrylate and dipropylene glycol di (meth) acrylate, and dioxane glycol di (meth) acrylate.

  Examples of the hydrocarbon-based or hydrocarbon ether-based trifunctional monomer or tetrafunctional monomer include, for example, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, glyceryl tri (meth) acrylate, Tri- or tetraol compounds such as pentaerythritol tetra (meth) acrylate and trimethylolpropane tetra (meth) acrylate, and tri (meth) acrylate or tetra (meth) acrylate, and alkylene oxide added to the above tri or tetraol compound Examples of the compound include tri (meth) acrylate and tetra (meth) acrylate.

  Examples of the non-urethane-based polyfunctional monomer other than the hydrocarbon-based or hydrocarbon-ether-based polyester include polyester poly (meth) acrylate and epoxy (meth) acrylate having two or more (meth) acrylate groups at terminals. Can be

(Peroxide)
As the peroxide suitably used as the crosslinking agent (D), any peroxide can be used as long as it can generate a radical by heating to achieve crosslinking of the pressure-sensitive adhesive. It is preferable to use a peroxide having a half-life time of preferably from 80 ° C to 160 ° C, more preferably from 90 ° C to 140 ° C. The half-life of peroxide is an index indicating the rate of decomposition of peroxide, and is the time during which the amount of decomposition of peroxide is halved, and the decomposition temperature for obtaining a half-life at any time. The half-life at an arbitrary temperature is described in a manufacturer's catalog and the like. For example, the 9th edition of an organic peroxide catalog issued by Nippon Oil & Fats Co., Ltd. (May 2003) Has been described.

  Examples of such peroxides include bis (2-ethylhexyl) peroxydicarbonate (1 minute half-life temperature 90.6 ° C) and bis (4-t-butylcyclohexyl) peroxydicarbonate (92.1 ° C). ), Bis-sec-butyl peroxydicarbonate (92.4 ° C.), t-butyl peroxy neodecanoate (103.5 ° C.), t-hexyl peroxypivalate, (109.1 ° C.) ), T-butyl peroxypivalate (110.3 ° C), dilauroyl peroxide (116.4 ° C), bis-n-octanoyl peroxide (117.4 ° C), 1,1,3 , 3-tetramethylbutylperoxy-2-ethylhexanoate (124.3 ° C), bis (4-methylbenzoyl) peroxide (128.2 ° C), dibenzoy Bis (4-t-butylcyclohexyl) peroxydicarbonate and dilauroylperoxide which are excellent in crosslinking reaction efficiency, such as peroxide (130.0 ° C) and t-butylperoxybutyrate (136.1 ° C). Oxides and dibenzoyl peroxide are preferably used. In particular, bis (4-t-butylcyclohexyl) peroxydicarbonate is preferred from the viewpoint of the decomposition temperature. One or more of these can be used. Moreover, you may use together with the above-mentioned isocyanate compound.

(Titanium coupling agent)
The titanium coupling agent suitably used as the cross-linking agent (D) is not particularly limited, and is not particularly limited. For example, those described in paragraph “0072” of JP-A-2014-085616 or those described above are appropriately used. Modified ones can be mentioned.

(Zirconium compound)
The zirconium compound suitably used as the cross-linking agent (D) is not particularly limited, and examples thereof include those described in paragraph “0073” of JP-A-2014-085616 or those appropriately modified.

(Aluminum chelate compound)
The aluminum chelate compound suitably used as the crosslinking agent (D) is not particularly limited, and includes, for example, those described in paragraph “0037” of JP-A-2008-251089 or those appropriately modified.

(Thermal acid generator)
Examples of the thermal acid generator include hexafluoroantimonate-based sulfonium salts, and commercially available products such as SI-60, SI-60L, SI-80, SI-80L, SI-100, and SI-100L (hereinafter, Sanshin) Chemical Industry Co., Ltd.) and CI-2624 (all manufactured by Nippon Soda Co., Ltd.). The thermal acid generators may be used alone or in combination of two or more. The amount of the thermal acid generator to be used is preferably 0.001 to 20 parts by mass, more preferably 0.05 to 10 parts by mass, based on 100 parts by mass of the base material (A). , 0.1 parts by mass or more and 3 parts by mass or less are more preferable.

[Silane coupling agent]
The pressure-sensitive adhesive composition of the present invention can further contain a silane coupling agent from the viewpoint of improving durability.

  The silane coupling agent refers to a compound having no siloxane bond and having two or more different reactive groups in a molecule.

  The silane coupling agent used in the pressure-sensitive adhesive composition of the present invention is not particularly limited. For example, 3-glycidoxypropyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, n-propyltrisilane Methoxysilane, ethyltrimethoxysilane, diethyldiethoxysilane, n-butyltrimethoxysilane, n-hexyltriethoxysilane, n-octyltrimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, cyclohexylmethyldimethoxysilane, vinyltrichloro Silane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glyciyl Doxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxy Propylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-β- (aminoethyl)- γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltri Methoki Silane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, bis- (3- [triethoxysilyl] propyl) tetrasulfide, γ-isocyanatopropyltriethoxysilane, etc. No. Furthermore, a silane coupling agent having a functional group such as an epoxy group (glycidoxy group), an amino group, a mercapto group, and a (meth) acryloyl group; and a silane coupling agent containing a functional group having reactivity with these functional groups. A compound having a hydrolyzable silyl group obtained by reacting a ring agent, another coupling agent, a polyisocyanate, or the like at an arbitrary ratio for each functional group can also be used.

  As the silane coupling agent, a commercially available product or a synthetic product may be used. Commercially available silane coupling agents include, for example, KBM-303, KBM-403, KBE-402, KBE-403, KBE-502, KBE-503, KBM-5103, KBM-573, KBM-802, KBM-403. 803, KBE-846 and KBE-9007 (all manufactured by Shin-Etsu Chemical Co., Ltd.).

  The silane coupling agents may be used alone or in combination of two or more.

  When the pressure-sensitive adhesive composition of the present invention contains a silane coupling agent, the content is preferably from 0.0001 to 10 parts by mass, based on 100 parts by mass of the main agent (A). It is more preferably from 001 parts by mass to 5 parts by mass, particularly preferably from 0.01 parts by mass to 3 parts by mass. Within such a range, the durability can be improved.

[solvent]
The pressure-sensitive adhesive composition of the present invention may contain a solvent. Examples of the solvent include, but are not particularly limited to, esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; cyclohexane; Organic solvents such as alicyclic hydrocarbons such as methylcyclohexane; ketones such as methyl ethyl ketone and methyl isobutyl ketone. These solvents can be used alone or in combination of two or more.

  Further, as described above, when the copolymer (C) is synthesized by a bulk polymerization method using a photopolymerization initiator, the obtained copolymer (C) contains the unreacted component (c1) and ( c2) A so-called polymer syrup containing at least one of the components as a solvent. Examples of the solvent used in the polymer syrup include the components (c1) and (c2) exemplified above. When the additive (B) is added, the additive (B) is dissolved in at least one of the component (c1) and the component (c2), and is prepared by dissolving the additive (B) in at least one of the component (c1) and the component (c2). It is preferable to use a solution containing the additive (B). Therefore, the pressure-sensitive adhesive composition of the present invention may contain at least one of the component (c1) and the component (c2) as a solvent in the composition.

[Other additives]
The pressure-sensitive adhesive composition may be, if necessary, a crosslinking accelerator, a tackifier resin (rosin derivative, polyterpene resin, petroleum resin, oil-soluble phenol, etc.), an antioxidant, a filler, a colorant (eg, pigment or dye). Known additives (other additives) such as an ultraviolet absorber, an antioxidant, a chain transfer agent, a plasticizer, a softener, a surfactant, and an antistatic agent within a range that does not impair the effects of the present invention. May be contained.

  When the main component (A) is in the form of a polymer syrup, the thermal polymerization initiator or the photopolymerization initiator described above is additionally added to perform a final copolymerization reaction to form an adhesive layer. Is also good. The addition amount of these polymerization initiators when added is preferably 0.025 parts by mass or more and 0.35 parts by mass or less based on 100 parts by mass of the base material (A).

[Method for producing pressure-sensitive adhesive composition]
The method for producing the pressure-sensitive adhesive composition is not particularly limited. For example, when the curable compound in the main component (A) is in the form of the above (1) in which only the monomer is used, the component (c1), the component (c2), the additive (B), and the crosslinking agent added as necessary (D), a method of mixing and producing a silane coupling agent, a solvent, and other additional components.

  When the curable compound in the main component (A) is in the form of the above (2) comprising a monomer and a polymer, a polymer syrup containing the component (c1), the component (c2), and the copolymer (B), and the additive (B) ), And a method of mixing and adding a crosslinking agent (D), a silane coupling agent, a solvent, and other additional components that are added as needed.

  When the curable compound in the main agent (A) is in the form of the above (3) consisting of only a polymer, the copolymer (C) or its solution, the additive (B), and the crosslinking agent (D ), A silane coupling agent, a solvent, and other additive components.

  As a method of adding the additive (B) according to the present invention, the additive (B) is dissolved in at least one of the component (c1) and the component (c2), and at least one of the component (c1) and the component (c2) is dissolved. It is preferable to prepare a solution containing one of the additives and the additive (B), and to add the obtained solution to the main agent (A) composed of a curable compound. According to this method, the additive (B) is more uniformly mixed in the pressure-sensitive adhesive composition, and at least one of the component (c1) and the component (c2) which are constituent units of the copolymer (C) is used. Since it is used as a solvent for the additive (B), the effect on the physical properties of the pressure-sensitive adhesive composition and the pressure-sensitive adhesive layer obtained after curing is small, which is preferable. At this time, the crosslinking agent (D) and other additional components added as necessary may be added to the solution containing the additive (B) or may be added to the main agent (A). And may be added to both.

  The content of the additive (B) in the solution containing at least one of the component (c1) and the component (c2) and the additive (B) is not particularly limited, but is 10% by mass or more and 75% by mass or less. Is preferred.

[Adhesive layer]
The present invention provides a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention. The pressure-sensitive adhesive layer of the present invention is a cured layer of the pressure-sensitive adhesive composition of the present invention. After applying (for example, applying) the pressure-sensitive adhesive composition (solution) of the present invention to an appropriate substrate (support), It can be formed by appropriately performing a curing treatment. When performing two or more types of curing treatments (drying, crosslinking, polymerization, etc.), these can be performed simultaneously or in multiple stages. In the pressure-sensitive adhesive composition in which the main component (A) contains the monomer of the component (c1) or the component (c2), a final copolymerization reaction is typically performed as the curing treatment ((c1)). Subjecting the component, component (c2), and / or copolymer (C) to a copolymerization reaction to form a complete polymer). For example, when using an active energy ray-curable pressure-sensitive adhesive composition, active energy ray irradiation is performed. If necessary, a curing treatment such as crosslinking or drying may be performed. When it is necessary to dry with an active energy ray-curable pressure-sensitive adhesive composition, it is preferable to perform active energy ray curing after drying. In the pressure-sensitive adhesive composition in which the main component (A) is composed of only the copolymer (C), typically, as the above-mentioned curing treatment, a treatment such as drying (heat drying) and crosslinking is performed as necessary. You.

  In applying the pressure-sensitive adhesive composition, one or more solvents may be newly added as appropriate.

  As a base material of the pressure-sensitive adhesive layer, a separator described later can be used.

  The coating method is not particularly limited, and various known methods are used. For example, roll coat, baker type applicator, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Examples include a method such as an extrusion coating method.

  When the pressure-sensitive adhesive composition of the present invention contains a solvent, it is preferable to dry the solvent. As a method for drying the solvent, an appropriate method can be adopted depending on the purpose. Preferably, a method of heating and drying the coating film is used. The heating and drying temperature is preferably from 40 ° C to 200 ° C, more preferably from 50 ° C to 180 ° C, and particularly preferably from 70 ° C to 170 ° C. By setting the heating temperature within the above range, a pressure-sensitive adhesive layer having excellent pressure-sensitive adhesive properties can be obtained.

  The drying time can be set as appropriate. It is preferably from 5 seconds to 30 minutes, more preferably from 5 seconds to 20 minutes, and particularly preferably from 10 seconds to 15 minutes. The heating and drying can be performed two or more times under different conditions.

When the pressure-sensitive adhesive composition of the present invention contains a photopolymerization initiator, the pressure-sensitive adhesive composition of the present invention is applied directly on an adherend, or a substrate, a predetermined target such as a separator. After coating, or after coating on one side on a support (substrate), the pressure-sensitive adhesive layer can be obtained by irradiating active energy rays. Normally, UV light having an illuminance of 1 mW / cm ² or more and 200 mW / cm ² or less at a wavelength of 200 nm or more and 400 nm or less is irradiated with an integrated light amount of about 200 mJ / cm ² or more and 4000 mJ / cm ² or less to cause photoadhesion. An agent layer is obtained.

  The thickness (dry film thickness) of the pressure-sensitive adhesive layer of the present invention is not particularly limited, and can be appropriately set depending on the intended use. For example, from the viewpoints of adhesion and bending resistance, the thickness is preferably 1 μm or more and 200 μm or less, more preferably 5 μm or more and 150 μm or less, and even more preferably 10 μm or more and 120 μm or less.

  Further, when the pressure-sensitive adhesive layer according to the present invention is exposed, the pressure-sensitive adhesive layer can be protected by a release-treated sheet (separator) or the like until it is practically used.

  Examples of the separator include a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate (PET) film, a polybutylene terephthalate (PBT) film, Plastic films such as a polyurethane film and an ethylene-vinyl acetate copolymer film are exemplified. Other suitable materials include porous materials such as paper, cloth, and nonwoven fabric, nets, foamed sheets, metal foils, and appropriate thin sheets such as laminates thereof. However, a plastic film is preferably used because of its excellent surface smoothness.

  The thickness of the separator is usually 5 μm or more and 200 μm or less, and preferably about 5 μm or more and 100 μm or less.

  If necessary, the separator may be a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent, release treatment and antifouling treatment with silica powder, coating type, kneading type, vapor deposition. Antistatic treatment of a mold or the like can be performed. In particular, by appropriately performing a release treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment on the surface of the separator, the releasability from the pressure-sensitive adhesive layer can be further improved.

  The preferred content of each structural unit of the polymer contained in the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of the present invention is as described in the section of {Content of each component in the above-mentioned (1) form}. Suitable contents of the components (component (c1) and component (c2)) are applied as they are.

[Adhesive sheet]
The present invention also provides a pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer of the present invention. The pressure-sensitive adhesive sheet is a so-called pressure-sensitive adhesive sheet with a substrate (single-sided) in which the pressure-sensitive adhesive layer is fixedly provided on one or both surfaces of a sheet-like substrate (support), that is, without intention of separating the pressure-sensitive adhesive layer from the substrate. Or a double-sided pressure-sensitive adhesive sheet), or the pressure-sensitive adhesive layer is provided on a substrate having releasability such as a release film (release liner) (release paper, a resin sheet having a surface subjected to release treatment, etc.). A so-called substrate-less (double-sided) pressure-sensitive adhesive sheet may be used, in which the substrate supporting the pressure-sensitive adhesive layer is removed at the time of application.

  Here, the concept of the pressure-sensitive adhesive sheet may include what is called a pressure-sensitive adhesive tape, a pressure-sensitive adhesive label, a pressure-sensitive adhesive film, or the like. The pressure-sensitive adhesive layer is not limited to a continuously formed pressure-sensitive adhesive layer. For example, the pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer formed in a regular or random pattern such as a dot or a stripe.

  Examples of the substrate (support) include plastic substrates such as polyethylene terephthalate (PET) and polyester film, porous materials such as paper and nonwoven fabric, and metal foil.

  The constituent material of the plastic substrate is not particularly limited as long as it can be formed into a sheet or a film. For example, polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1- Polyolefins such as pentene, ethylene / propylene copolymer, ethylene / 1-butene copolymer, ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, ethylene / vinyl alcohol copolymer; polyethylene terephthalate, polyethylene na Polyesters such as phthalate and polybutylene terephthalate; polyamides such as polyacrylate, polystyrene, nylon 6, nylon 6,6, and partially aromatic polyamide; polyvinyl chloride, polyvinylidene chloride, and polycarbonate.

  The thickness of the substrate is not particularly limited, but is preferably 4 μm or more and 100 μm or less, more preferably 4 μm or more and 25 μm or less.

  The plastic substrate may be, if necessary, a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent, release with a silica powder or the like, antifouling treatment, acid treatment, alkali treatment, primer treatment. It is also possible to perform an easy adhesion treatment such as a corona treatment, a plasma treatment, and an ultraviolet treatment, and an antistatic treatment such as a coating type, a kneading type, and a vapor deposition type.

  Examples of the release film (release liner) include the separators exemplified above.

[Use]
The above-mentioned pressure-sensitive adhesive composition, pressure-sensitive adhesive layer, and pressure-sensitive adhesive sheet of the present invention are applied to various uses, and are used, for example, for optical films. Such an optical film is not particularly limited and includes those used for forming an image display device such as a liquid crystal display device. Examples thereof include at least a polarizing plate or a retardation plate, and further include a conductive layer and a protective layer. And at least one of the above, a cover film, a transparent conductive film, a window film, an optical compensation film such as a viewing angle widening film for improving the viewing angle of a liquid crystal display, a brightness enhancement film for increasing the contrast of the display, and more. The thing which these were laminated | stacked is mentioned.

  The pressure-sensitive adhesive composition, pressure-sensitive adhesive layer, and pressure-sensitive adhesive sheet of the present invention are suitably used for an image display device. Examples of the image display device include a liquid crystal display device, an organic EL display device, a plasma display (PDP), a curved display, a flexible display, and the like.

  As described above, the present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet, and an image display device, and an adhesive force, and peeling or floating occurs even when bending under high-temperature and low-temperature conditions. It is possible to provide a pressure-sensitive adhesive composition having an excellent balance between bending resistance and almost no bending resistance. Further, the pressure-sensitive adhesive composition of the present invention is suitably used for the production of various films or sheets used for liquid crystal display devices such as flexible displays and electroluminescence devices, and is commercially available in these technical fields. What you get.

  Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples. The room temperature standing conditions not particularly specified below are all 23 ° C. and 55% RH.

<Measurement of weight average molecular weight (Mw) of (meth) acrylate copolymer (C)>
The weight average molecular weight (Mw) of the (meth) acrylate copolymer (C) was measured using GPC (gel permeation chromatography) under the following measurement conditions.

・ Analyzer: Tosoh Corporation, HLC-8120GPC
・ Column: G7000HXL + GMHXL + GMHXL, manufactured by Tosoh Corporation
・ Column size: 7.8mmφ × 30cm each 90cm in total
-Column temperature: 40 ° C
・ Flow rate: 0.8 ml / min
・ Injection volume: 100 μl
・ Eluent: tetrahydrofuran ・ Detector: differential refractometer (RI)
-Standard sample: polystyrene.

(Example 1)
In an environment where external ultraviolet rays were cut off, four black lights (FL20SBL, manufactured by Sankyo Electric Co., Ltd.) as UV lamps were reacted in a reaction box installed on four sides of the flask.

  81 parts by mass of 2-ethylhexyl acrylate (component (c1), 2EHA, manufactured by Nippon Shokubai Co., Ltd.) and N-hydroxyethyl were placed in a reaction vessel equipped with a stirrer, thermometer, nitrogen gas inlet tube, and cooling tube in the above box. Acrylamide ((c2-1) component, HEAA (registered trademark), 1 part by mass of KJ Chemicals Co., Ltd.), 4-hydroxybutyl acrylate (c2-2) component, 4HBA, 15 parts by mass of Nippon Kasei Co., Ltd., methyl 1 part by mass of a methacrylate macromonomer ((c2-3) component, AA-6, manufactured by Toagosei Co., Ltd.), methoxypolyethylene glycol acrylate ((c2-4) component, AM-130G, and the number of repeating oxyethylene groups is 13 , Manufactured by Shin-Nakamura Chemical Co., Ltd.), and the air in the flask was replaced with nitrogen.

  Next, as a polymerization initiator, 0.005 parts by mass of 2,2-dimethoxy-1,2-diphenylethan-1-one (Irgacure (registered trademark) 651, manufactured by BASF Japan Co., Ltd.) was charged under stirring and homogenized. Was mixed.

Here, in order to start polymerization, ultraviolet rays having a wavelength of 360 nm and an illuminance of 4 mW / cm ² were irradiated at room temperature (23 ° C.) using a black light. At the stage when the temperature of the reaction system increased after the start of the reaction and the reaction temperature increased from the start of the reaction to 7 ° C., the reaction was forcibly stopped by introducing air into the flask with an air pump to thereby stop the polymerization. A syrup (base agent (A)) (polymerization rate 7%) was obtained. The weight average molecular weight (Mw) of the (meth) acrylate copolymer (C) contained in the polymer syrup is 1.5 million, and the content of the copolymer (C) with respect to the total mass of the polymer syrup (base material (A)) The amount was 7% by weight. The “polymerization rate” is a value of the reaction rate calculated assuming that 100% is obtained when all of the charged monomers become polymers.

  A solution is prepared by dissolving 50 parts by mass of cresyl diphenyl phosphate (trade name: CDP, manufactured by Daihachi Chemical Industry Co., Ltd., freezing point: -30 ° C.) as the additive (B) in 50 parts by mass of 2-ethylhexyl acrylate. did. This solution was prepared by adding the additive (B) to the polymer syrup (main agent (A)) with respect to the polymer syrup (main agent (A)) containing the (meth) acrylate copolymer (C) prepared above. )) 5 parts by mass with respect to 100 parts by mass, and 1-hydroxycyclohexyl phenyl ketone (Irgacure (registered trademark) 184, manufactured by BASF Japan Ltd.) was further added at 0 part by mass with respect to 100 parts by mass of the base material (A). In addition, an adhesive composition was prepared so as to be 0.3 parts by mass.

(Example 2)
Except that the monomer composition was changed to 81 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of 4-hydroxybutyl acrylate, 1 part by mass of methyl methacrylate macromonomer and 3 parts by mass of methoxypolyethylene glycol acrylate, in the same manner as in Example 1. Then, an adhesive composition was prepared (polymerization ratio: 7%). The Mw of the obtained copolymer (C) was 1.7 million, and the content of the copolymer (C) was 7% by mass relative to the total mass of the polymer syrup (base material (A)).

(Example 3)
Except that the monomer composition was changed to 95 parts by mass of 2-ethylhexyl acrylate, 1 part by mass of N-hydroxyethylacrylamide, 1 part by mass of methyl methacrylate macromonomer and 3 parts by mass of methoxypolyethylene glycol acrylate, in the same manner as in Example 1. Then, an adhesive composition was prepared (polymerization ratio: 7%). The Mw of the obtained copolymer (C) was 2.9 million, and the content of the copolymer (C) was 7% by mass relative to the total mass of the polymer syrup (base material (A)).

(Example 4)
Except that the monomer composition was changed to 81 parts by mass of 2-ethylhexyl acrylate, 1 part by mass of N-hydroxyethyl acrylamide, 15 parts by mass of 4-hydroxybutyl acrylate, and 3 parts by mass of methoxypolyethylene glycol acrylate, the same as in Example 1. Thus, an adhesive composition was prepared (polymerization ratio: 7%). The Mw of the obtained copolymer (C) was 1.92 million, and the content of the copolymer (C) was 7% by mass relative to the total mass of the polymer syrup (main component (A)).

(Example 5)
Same as Example 1 except that the monomer composition was changed to 83 parts by mass of 2-ethylhexyl acrylate, 1 part by mass of N-hydroxyethylacrylamide, 15 parts by mass of 4-hydroxybutyl acrylate and 1 part by mass of methyl methacrylate macromonomer. Thus, an adhesive composition was prepared (polymerization ratio: 7%). The Mw of the obtained copolymer (C) was 1.6 million, and the content of the copolymer (C) was 7% by mass based on the total mass of the polymer syrup (base material (A)).

(Example 6)
Instead of the cresyl diphenyl phosphate solution, 50 parts by mass of triisodecyl trimellitate (trade name: T-10, manufactured by Kao Corporation, freezing point: -30 ° C) as an additive (B) is added to 50 parts by mass of 2-ethylhexyl acrylate. An adhesive composition was prepared in the same manner as in Example 4, except that the dissolved solution was used.

(Example 7)
Instead of the cresyl diphenyl phosphate solution, 50 parts by mass of tris (2-ethylhexyl) trimellitate (trade name: TOTM, manufactured by J-PLUS Co., Ltd., freezing point: -30 ° C) as an additive (B) is 2-ethylhexyl. Except having used the solution melt | dissolved in 50 mass parts of acrylates, it carried out similarly to Example 4, and produced the adhesive composition.

(Example 8)
Instead of the cresyl diphenyl phosphate solution, 50 parts by mass of trixylenyl phosphate (trade name: TXP, manufactured by Daihachi Chemical Industry Co., Ltd., freezing point: -15 ° C) as an additive (B) is 50 parts by mass of 2-ethylhexyl acrylate. A pressure-sensitive adhesive composition was prepared in the same manner as in Example 4 except that the solution dissolved in was used.

(Comparative Example 1)
An adhesive composition was prepared in the same manner as in Example 4, except that the cresyl diphenyl phosphate solution was not added.

(Comparative Example 2)
Instead of the cresyl diphenyl phosphate solution, a solution prepared by dissolving 50 parts by mass of epoxidized soybean oil (trade name: Kapox S-6, manufactured by Kao Corporation, freezing point: 5 ° C.) in 50 parts by mass of 2-ethylhexyl acrylate is used. A pressure-sensitive adhesive composition was prepared in the same manner as in Example 4 except for the fact that the adhesive was used.

(Comparative Example 3)
Instead of the cresyl diphenyl phosphate solution, 50 parts by mass of tris (2-ethylhexyl) phosphate (trade name: TOP, manufactured by Daihachi Chemical Industry Co., Ltd., freezing point: -70 ° C. or less) is dissolved in 50 parts by mass of 2-ethylhexyl acrylate. An adhesive composition was prepared in the same manner as in Example 4 except that the solution thus obtained was used.

(Comparative Example 4)
Instead of the cresyl diphenyl phosphate solution, a solution prepared by dissolving 50 parts by mass of dibutyl adipate (trade name: DBA, manufactured by Daihachi Chemical Industry Co., Ltd., freezing point: −22 ° C.) in 50 parts by mass of 2-ethylhexyl acrylate was used. Except for this, an adhesive composition was prepared in the same manner as in Example 4.

(Comparative Example 5)
A polymer syrup (base material (A)) was prepared in the same manner as in Example 1, except that the monomer composition was changed to 80 parts by mass of 2-ethylhexyl acrylate and 20 parts by mass of 4-hydroxybutyl acrylate. 7%). The Mw of the obtained copolymer (C) was 2,000,000, and the content of the copolymer (C) was 7% by mass relative to the total mass of the polymer syrup (base material (A)).

  Separately, a resin obtained by acrylic-modifying a polyol-modified xylene resin (trade name: Nicanol (registered trademark) K-100, manufactured by Fudo Co., Ltd.) was synthesized. In a 100 ml flask equipped with a stirrer, 20 g of Nicanol (registered trademark) K-100 and 24.53 g of 2-ethylhexyl acrylate were charged and stirred at room temperature (25 ° C.). After visually confirming that the mixture was uniformly mixed, 4.53 g of an acrylate compound having an isocyanate group (2-isocyanatoethyl acrylate, Karenz AOI (registered trademark), manufactured by Showa Denko KK), a polymerization inhibitor 0.491 g of an ethyl acetate solution (concentration: 5% by mass) of Q-1301 (aluminum salt of N-nitroso-N-phenylhydroxylamine) and 1.0 g of a tin catalyst (promoter S, manufactured by Soken Chemical Co., Ltd.) It was dropped into the reaction system. After completion of the dropwise addition, the mixture was heated to 85 ° C., stirred for 1 hour, and reacted. After completion of the reaction, the mixture was cooled to obtain a polyol-modified xylene resin modified with acrylic (acryl-modified xylene resin).

  A solution in which 50 parts by mass of the obtained acrylic-modified xylene resin was dissolved in 50 parts by mass of 2-ethylhexyl acrylate was prepared. This solution was added to the polymer syrup (base agent (A)) containing the (meth) acrylate copolymer (C) prepared above, and the amount of the acryl-modified xylene resin was adjusted to 100 parts by mass of the base agent (A). And 1 part by weight of 1-hydroxycyclohexyl phenyl ketone (Irgacure (registered trademark) 184, manufactured by BASF Japan KK) in an amount of 0.3 part by mass with respect to 100 parts by mass of the copolymer (C). In addition, a pressure-sensitive adhesive composition was prepared.

(Comparative Example 6)
Adhesive composition was prepared in the same manner as in Example 7, except that the amount of tris (2-ethylhexyl) trimellitate was changed to 9 parts by mass with respect to 100 parts by mass of the copolymer (C). A product was made.

(Comparative Example 7)
Except that the monomer composition was changed to 75 parts by mass of 2-ethylhexyl acrylate, 5 parts by mass of 4-hydroxybutyl acrylate, and 20 parts by mass of N-hydroxyethyl acrylamide, a pressure-sensitive adhesive composition was prepared in the same manner as in Example 1. It was produced (polymerization ratio: 7%). The weight average molecular weight (Mw) of the obtained copolymer (C) was 1.7 million, and the content of the copolymer (C) in the polymer syrup (base material (A)) was 7% by mass. .

  The constitutions of the pressure-sensitive adhesive compositions of Examples and Comparative Examples are shown in Table 1 below.

<Measurement of storage modulus>
The pressure-sensitive adhesive composition is applied on a PET film (trade name: MRF50, manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., thickness: 50 μm) which has been subjected to a release treatment with a silicone-based release agent, using a baker-type applicator. Thus, a coating film was obtained. Thereafter, another PET film subjected to a release treatment with the same silicone-based release agent as described above is overlaid on the obtained coating film, and black light (FL20SBL, manufactured by Sankyo Electric Co., Ltd.) is used. UV light (wavelength: 360 nm) with an illuminance of 2.5 mW / cm ² was irradiated for 10 minutes (integrated light amount: 1500 mJ / cm ² ) to cure the coating film. Thus, a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer having a thickness of 50 μm was sandwiched between two PET films was obtained.

  The obtained pressure-sensitive adhesive sheet was cut into a size of 1.0 mm × 1.0 mm, the two PET films were peeled off, and the pressure-sensitive adhesive layer was taken out. The pressure-sensitive adhesive layer (cured pressure-sensitive adhesive composition) was attached to a dynamic viscoelasticity measurement device (Exstar DMS7100, manufactured by Hitachi High-Tech Science Corporation). The measurement was carried out in a shearing mode, a frequency of 1 Hz, and a temperature rising rate of 5 ° C./min in a temperature range from −30 ° C. to 100 ° C., and the storage elastic modulus G ′ (− 20) at −20 ° C. and 80 ° C. The storage modulus G '(80) was measured.

<Measurement of glass transition temperature>
Except that the thickness of the pressure-sensitive adhesive layer was changed to 100 μm, a pressure-sensitive adhesive sheet was obtained in the same manner as in the above <Measurement of storage elastic modulus>.

  A small amount of the pressure-sensitive adhesive layer was taken out of the obtained pressure-sensitive adhesive sheet and attached to a differential scanning calorimeter (DSC, manufactured by Seiko Instruments Inc., EXSTAR6000, autosampler: ASD-2). The temperature was measured at a temperature rising rate of 10 ° C./min in a temperature range of −130 ° C. or more and 100 ° C. or less, and the temperature of the endothermic peak derived from the pressure-sensitive adhesive layer in the first heating process was measured. Transition temperature (Tg).

[Evaluation]
<Measurement of shear strength (adhesive strength)>
The pressure-sensitive adhesive composition was applied on a 50 μm-thick PET film (trade name: MRF50, manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.) using a baker-type applicator to obtain a coating film. The obtained coating film was irradiated with ultraviolet light (wavelength: 360 nm) having an illuminance of 2.5 mW / cm ² for 10 minutes using a black light (integrated light amount: 1500 mJ / cm ² ) to form an adhesive layer having a thickness of 100 μm. Obtained.

A joint-shaped test piece was prepared from the obtained PET film with the pressure-sensitive adhesive layer so that the adhesion area between the PET film and the pressure-sensitive adhesive layer was 4 cm ² . This test piece was attached to a tensile tester (trade name: Tensilon Universal Material Testing Machine STA-1150, manufactured by Orientec Co., Ltd.), and the load when shearing deformation was performed by 1000% at a chuck moving speed of 30 mm / min was measured. The value obtained by dividing the measured load by the bonding area was defined as the shear strength.

<Bending test>
In the same manner as that used for the measurement of the storage elastic modulus, a pressure-sensitive adhesive sheet in which a pressure-sensitive adhesive layer having a thickness of 50 μm was sandwiched between two release PET films was produced. The pressure-sensitive adhesive layer was taken out from the prepared pressure-sensitive adhesive sheet, and a 50-μm-thick pressure-sensitive adhesive sheet was stuck on a 188-μm-thick PET film (trade name: A4300, manufactured by Toyobo Co., Ltd.) using a handler, and further, A 100-μm-thick PET film (trade name: A4100, manufactured by Toyobo Co., Ltd.) was overlaid and autoclaved at 50 ° C. and 0.5 MPa for 15 minutes to completely adhere. Thus, a pressure-sensitive adhesive sheet in which two PET films were bonded by a pressure-sensitive adhesive layer having a thickness of 50 μm was obtained.

  Using a bending tester (trade name: bending tester, manufactured by Tester Sangyo Co., Ltd.), the obtained pressure-sensitive adhesive sheet was subjected to a repeated bending load having a curvature of 3 mm at a temperature of 60 ° C. or −20 ° C. (1 hour). (300 cycles, number of repetitions: 30,000 times), and it was visually confirmed whether the pressure-sensitive adhesive layer and the PET film had peeled, floated, and had wrinkles. In the table, ○ indicates that there was no peeling, floating, wrinkles, etc., Δ indicates that there was no peeling but wrinkles occurred in the pressure-sensitive adhesive layer, and X indicates that there was peeling. If it is Δ or more, it is practical.

  The evaluation results are shown in Table 2 below.

  As shown in Table 2 above, it can be seen that the pressure-sensitive adhesive compositions of the examples have an excellent balance between the adhesive strength and the bending resistance under high-temperature conditions and low-temperature conditions. On the other hand, it was found that the pressure-sensitive adhesive composition of the comparative example had an inferior balance between the adhesive strength and the bending resistance under high-temperature conditions and low-temperature conditions.

Claims (10)

A main agent (A) comprising a curable compound,
At least one additive (B) selected from the group consisting of a trisubstituted aromatic compound, a triaryl phosphate, an aliphatic tricarboxylic acid ester, an alicyclic tricarboxylic acid ester, and a polyoxyalkylene sorbitan fatty acid ester;
An adhesive composition comprising:
The curable compound has a structural unit derived from a (meth) acrylic acid alkyl ester monomer (c1) and a structural unit derived from a monomer (c2) copolymerizable with the (meth) acrylic acid alkyl ester monomer. Including acrylic ester copolymer (C),
The content of the (meth) acrylate copolymer (C) with respect to the total mass of the main agent (A) is 3% by mass or more and 25% by mass or less,
The content of the additive (B) is 0.1 parts by mass or more and 8 parts by mass or less based on 100 parts by mass of the main agent (A),
The storage elastic modulus G ′ (80) at 80 ° C. after curing is 1.72 × 10 ⁴ Pa or more and 4.0 × 10 ⁴ Pa or less, and the storage elastic modulus G ′ (− 20 at −20 ° C. after curing. ) Is smaller than 13 times the G ′ (80),
An adhesive composition having a shear strength of less than 60 kPa when subjected to a shear deformation of 1000% at a shear rate of 30 mm / min after curing. The (meth) acrylate copolymer (C) is:
A structural unit derived from the (meth) acrylic acid alkyl ester monomer (c1), in an amount of 9.9% by mass to 99.9% by mass;
As a structural unit derived from the monomer (c2) copolymerizable with the alkyl (meth) acrylate monomer,
Structural unit derived from (meth) acrylic monomer (c2-1) having an amide group, from 0% by mass to 15% by mass;
Structural unit derived from a functional group-containing monomer (c2-2), which is a (meth) acrylate monomer having no plurality of radically polymerizable functional groups, from 0% by mass to less than 20% by mass;
Structural unit derived from macromonomer (c2-3) having a polymerizable functional group, from 0% by mass to less than 15% by mass; and component (c1), component (c2-1), component (c2-2), and component (c2) -3) a constituent unit derived from a (meth) acrylate monomer (c2-4) other than the component, from 0% by mass to 90% by mass;
(However, the total amount of the structural units derived from the components (c1), (c2-1), (c2-2), (c2-3) and (c2-4) is 100% by mass.)
The pressure-sensitive adhesive composition according to claim 1 , comprising: Freezing point of the additive (B) is less than -20 ° C., the pressure-sensitive adhesive composition according to claim 1 or 2. The pressure-sensitive adhesive composition according to any one of claims 1 to 3 , wherein the additive (B) has three or more functional groups having a molecular weight of 78 or more. The said additive (B) is at least 1 sort (s) selected from the group which consists of tris (2-ethylhexyl) trimellitate, triisodecyl trimellitate, cresyl diphenyl phosphate, and trixylenyl phosphate. 5. The pressure-sensitive adhesive composition according to any one of the above items 4 . The pressure-sensitive adhesive composition according to any one of claims 1 to 5 , wherein a glass transition temperature after curing is -50C or less. A pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition according to any one of claims 1 to 6 . An adhesive sheet having the adhesive layer according to claim 7 . Having a pressure-sensitive adhesive sheet according to the pressure-sensitive adhesive layer or claim 8 according to claim 7, the image display device. At least one of the alkyl (meth) acrylate monomer (c1) and the monomer (c2) copolymerizable with the alkyl (meth) acrylate monomer, a trisubstituted aromatic compound, a triaryl phosphate, an aliphatic tricarboxylic acid At least one additive (B) selected from the group consisting of an acid ester, an alicyclic tricarboxylic acid ester, and a polyoxyalkylene sorbitan fatty acid ester;
A method for producing a pressure-sensitive adhesive composition, comprising adding the solution to a main agent (A) comprising a curable compound.