JP2021050341A - Transparent double-sided adhesive sheet and adhesive sheet laminate - Google Patents

Abstract

To propose a new transparent double-sided adhesive sheet for image display devices that has an ultraviolet absorption function, in which the transparent double-sided adhesive sheet can be primarily stuck, using an adhesive sheet, and then cured for secondary sticking.SOLUTION: The present invention propose a new transparent double-sided adhesive sheet for image display devices that comprises an adhesive resin composition comprising a (meth) acrylic copolymer (A), a crosslinking agent (B), a photopolymerization initiator (C) with a molar extinction coefficient of 10 or more at the wavelength 405 nm, and an ultraviolet absorber (D).SELECTED DRAWING: None

Description

The present invention relates to a transparent double-sided adhesive sheet that can be used as a member for constituting an image display device such as a personal computer, a mobile terminal (PDA), a game machine, a television (TV), a car navigation system, a touch panel, a pen tablet, or the like. ..

In recent years, in order to improve the visibility of an image display device, an image display panel such as a liquid crystal display (LCD), a plasma display (PDP), or an electroluminescence display (ELD) and protection arranged on the front side (visual side) thereof. By filling the gap between the panel and the touch panel member with an adhesive, the reflection of the incident light and the emitted light from the display image at the air layer interface is suppressed.

As a method of filling the gaps between the constituent members of the image display device with an adhesive, there is a method of filling the gaps with a liquid adhesive resin composition containing an ultraviolet curable resin and then irradiating the voids with ultraviolet rays to cure the voids. It is known (Patent Document 1).

Further, a method of filling the gaps between the constituent members of the image display device with an adhesive sheet is also known. For example, Patent Document 2 discloses a method in which an adhesive sheet primaryly crosslinked by ultraviolet rays is attached to an image display device constituent member, and then the adhesive sheet is irradiated with ultraviolet rays via the image display device constituent member to be secondarily cured. ..

Patent Document 3 describes an adhesive sheet made of a hot melt type adhesive composition containing urethane (meth) acrylate having a weight average molecular weight of 20,000 to 100,000 as a main component and having a loss tangent of less than 1 at 25 ° C. A method of filling a gap between constituent members for an image display device is disclosed.

International Publication No. 2010/027041 Japanese Patent No. 4971529 International Publication No. 2010/0383366

By the way, when two image display device constituent members are attached by using a pressure-sensitive adhesive sheet composed of a pressure-sensitive adhesive resin composition containing a base resin, a cross-linking agent and an ultraviolet polymerization initiator, the two image display device constituent members are attached. After primary attachment via the adhesive sheet, ultraviolet rays are irradiated from the outside of one image display device component, and the adhesive sheet is ultraviolet-cured through the image display device component to be secondarily attached. According to this, it is possible to perform primary adhesion while filling the unevenness of the adherend surface, and further, it is possible to finally cure the adhesive to further improve the adhesive reliability.
However, when the adhesive sheet having such ultraviolet sensitivity is exposed to ultraviolet rays for a long period of time, the deterioration of the adhesive sheet itself progresses, and there is a possibility that decomposition products are generated and foaming or peeling occurs.
Further, since some of the image display device constituent members are easily deteriorated by ultraviolet rays, in such a case, the two image display device constituent members cannot be attached by the above method.
Further, when the image display device component has ultraviolet absorption, the ultraviolet rays do not sufficiently reach the adhesive sheet even if the ultraviolet rays are irradiated through the members. Therefore, even in such a case, the above method is used. It is not possible to attach the two image display device components to each other.

On the other hand, as the image display device becomes thinner, new functions are required for the adhesive sheet. In order to prevent ultraviolet deterioration of liquid crystals, organic EL elements, polarizing plates, etc., image display device components may be required to have an ultraviolet absorbing function, and the ultraviolet absorbing function is generally secured by a polarizing plate protective film. It was. However, with the thinning of the constituent members of the image display device, the thinning of the polarizing plate protective film has progressed, and it has become difficult to obtain a sufficient ultraviolet absorbing function. Therefore, image display device components other than the polarizing plate protective film, such as an adhesive or an adhesive sheet, are also required to have an ultraviolet absorbing function.

However, it is difficult to impart an ultraviolet absorbing function to the ultraviolet curable type adhesive sheet as described above. On the other hand, if the adhesive sheet is used to fill in the unevenness of the adherend surface and then the primary attachment is performed, and then the adhesive sheet is further cured to perform the secondary attachment, the adherend surface of the bonding member may have irregularities. There is a problem that it is not possible to achieve both the step absorption property and the foaming reliability and reliability after bonding.

Therefore, the present invention provides a new transparent double-sided adhesive sheet which has an ultraviolet absorbing function and can be first-attached using an adhesive sheet and then further cured to be secondarily attached. is there.

The present invention relates to a (meth) acrylic copolymer (A), a cross-linking agent (B), a photopolymerization initiator (C) having an extinction coefficient of 10 mL / (g · cm) or more at a wavelength of 405 nm, and an ultraviolet absorber ( A single layer or two or more pressure-sensitive adhesive layers formed from the pressure-sensitive adhesive resin composition containing D).
The adhesive layer is a transparent double-sided adhesive sheet containing at least a polyfunctional (meth) acrylate as the cross-linking agent (B) and capable of photocuring.

The transparent double-sided adhesive sheet for image display of the present invention has an ultraviolet absorbing function, and can be first-attached using the adhesive sheet and then photo-cured for secondary attachment. It is possible to achieve both the step absorption when the adherend surface is uneven and the foaming reliability after bonding.

Hereinafter, an example of the embodiment of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

<Book adhesive sheet>
The transparent double-sided pressure-sensitive adhesive sheet according to an example of the embodiment of the present invention is a (meth) acrylic copolymer (A), a cross-linking agent (B), and light having an absorption coefficient of 10 mL / (g · cm) or more at a wavelength of 405 nm. It is a transparent double-sided pressure-sensitive adhesive sheet (referred to as "the present pressure-sensitive adhesive sheet") composed of a pressure-sensitive adhesive resin composition (referred to as "the present pressure-sensitive adhesive composition") containing a polymerization initiator (C) and an ultraviolet absorber (D).

[(Meta) acrylic copolymer (A)]
The (meth) acrylic polymer as the base polymer of this pressure-sensitive adhesive sheet has a glass transition temperature (Tg), etc., depending on the type, composition ratio, polymerization conditions, etc. of the acrylic monomer and methacrylic monomer used for polymerizing the polymer. It is possible to adjust the characteristics of the above as appropriate.

The "base polymer" in the pressure-sensitive adhesive sheet means a resin that forms the main component of the pressure-sensitive adhesive sheet. It does not specify the specific content. As a guide, the resin occupies 50% by mass or more, particularly 65% by mass or more, and 80% by mass or more (including 100% by mass) by mass or more of the resin contained in the present adhesive sheet. When there are two or more types of base polymers, the total amount thereof corresponds to the content.

The (meth) acrylic (co) polymer (A) is, for example, a copolymer obtained by polymerizing a homopolymer of alkyl (meth) acrylate and a monomer component having copolymerizability. More preferably, from alkyl (meth) acrylate and copolymerizable carboxyl group-containing monomer, hydroxyl group-containing monomer, amino group-containing monomer, epoxy group-containing monomer, amide group-containing monomer and other vinyl monomers. Examples thereof include a copolymer containing any one or more selected monomers as a monomer component.

More specifically, a linear or branched alkyl (meth) acrylate having 4 to 18 carbon atoms in the side chain (hereinafter, also referred to as "copolymerizable monomer A"), and a carboxyl group-containing monomer copolymerizable therewith (hereinafter, hereinafter). "Copolymerizable monomer B"), vinyl monomer (hereinafter also referred to as "copolymerizable monomer C"), (meth) acrylate having 1 to 3 carbon atoms in the side chain (hereinafter "copolymerizable monomer D") ”) And a copolymer composed of any one or more of the monomers selected from the hydroxyl group-containing monomer (hereinafter,“ copolymerizable monomer E ”).

Further, it is copolymerized with (a) a copolymer composed of a copolymerizable monomer A and a monomer component containing a copolymerizable monomer B and / or a copolymerizable monomer C, and (b) a copolymerizable monomer A. A copolymer composed of a copolymerization monomer B and / or a copolymerizable monomer C and a monomer component containing a copolymerizable monomer D and / or a copolymerizable monomer E can also be mentioned as a particularly suitable example. Specifically, copolymers of copolymerizable monomers A and B, copolymers of copolymerizable monomers A and C, copolymers of copolymerizable monomers A, B and C, copolymerizable monomers A and B. And D copolymers, copolymers A, B and E copolymers, copolymers A, B, D and E copolymers, copolymers A, C and D copolymers , Copolymers of copolymerizable monomers A, C and E, copolymers of copolymerizable monomers A, C, D and E, copolymers of copolymerizable monomers A, B, C and D, copolymerizability Examples thereof include copolymers of the monomers A, B, C and E, and copolymers of the copolymerizable monomers A, B, C, D and E.

Examples of the "copolymerizable monomer A" include n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, and isopentyl. (Meta) acrylate, neopentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate , Nonyl (meth) acrylate, isononyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) Acrylate, tetradecyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, isobornyl (meth) acrylate, 3,5,5-trimethylcyclohexane (meth) acrylate, dicyclopentanyl Examples thereof include (meth) acrylate, dicyclopentenyl (meth) acrylate, and dicyclopentenyloxyethyl (meth) acrylate. These may be used alone or in combination of two or more.

The copolymerizable monomer A is preferably contained in the total monomer component of the copolymer in an amount of 30% by mass or more and 90% by mass or less, particularly 35% by mass or more or 88% by mass or less, and particularly 40% by mass or more. Alternatively, it is more preferably contained in the range of 85% by mass or less.

Examples of the "copolymerizable monomer B" include (meth) acrylic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxypropyl hexahydrophthalic acid, and 2- (meth). Acryloyloxyethylphthalic acid, 2- (meth) acryloyloxypropylphthalic acid, 2- (meth) acryloyloxyethylmaleic acid, 2- (meth) acryloyloxypropylmaleic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (Meta) acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid can be mentioned. These may be one kind or a combination of two or more kinds. In addition, "(meth) acrylic" means to include acrylic and methacrylic. Similarly, "(meth) acryloyl" means to include acryloyl and methacryloyl.

Examples of the "copolymerizable monomer C" include compounds having a vinyl group in the molecule. Such compounds include (meth) acrylic acid alkyl esters having an alkyl group having 1 to 12 carbon atoms, functional monomers having a functional group such as a hydroxyl group, an amide group and an alkoxylalkyl group in the molecule, and functional monomers. Polyalkylene glycol di (meth) acrylates and vinyl ester monomers such as vinyl acetate, vinyl propionate and vinyl laurate and aromatic vinyl monomers such as styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene and other substituted styrenes. Can be exemplified. These may be one kind or a combination of two or more kinds.

The above-mentioned copolymerizable monomer B and the above-mentioned copolymerizable monomer C are 1.2% by mass to 15% by mass or less in all the monomer components of the copolymer, and 1.5% by mass or more from the viewpoint of obtaining excellent adhesive properties. Alternatively, it is preferably contained in the range of 10% by mass or less, particularly 2% by mass or more or 8% by mass or less.

Examples of the "copolymerizable monomer D" include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate and the like. These may be one kind or a combination of two or more kinds.
The copolymerizable monomer D is preferably contained in the total monomer component of the copolymer in an amount of 0% by mass or more and 70% by mass or less, particularly 3% by mass or more or 65% by mass or less, and particularly 5% by mass or more or It is more preferably contained in the range of 60% by mass or less.

Examples of the "copolymerizable monomer E" include hydroxyalkyls such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate. (Meta) acrylates can be mentioned. These may be one kind or a combination of two or more kinds.

The copolymerizable monomer E is preferably contained in the total monomer component of the copolymer in an amount of 0% by mass or more and 30% by mass or less, particularly 0% by mass or more or 25% by mass or less, and particularly 0% by mass or more or 0% by mass or less. It is more preferably contained in the range of 20% by mass or less.

In addition to those listed above, acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride, glycidyl (meth) acrylate, glycidyl α-ethylacrylate, and epoxy such as 3,4-epoxybutyl (meth) acrylate. Group-containing monomer, amino group-containing (meth) acrylic acid ester-based monomer such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate, (meth) acrylamide, N-t-butyl (meth) acrylamide, N-methylol Monomers containing amide groups such as (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone (meth) acrylamide, maleic acid amide, maleimide, vinyl pyrrolidone, vinyl pyridine, etc. A heterocyclic basic monomer such as vinylcarbazole can be appropriately used as needed.

Specific examples of the (meth) acrylic (co) polymer include 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, and isostearyl (meth). ) Acrylate, butyl (meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate and other monomer components (a), (meth) acrylic acid having a carboxyl group, 2- (meth) acryloyloxyethyl hexahydrophthal. Acids, 2- (meth) acryloyloxypropylhexahydrophthalic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxypropylphthalic acid, 2- (meth) acryloyloxyethyl maleic acid, 2- With monomer components (b) such as (meth) acryloyloxypropyl maleic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxypropyl maleic acid, crotonic acid, fumaric acid, maleic acid, and itaconic acid. , Hydroxyethyl (meth) acrylate with organic functional groups, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, glycerol (meth) acrylate, monomethyl maleate, monomethyl itacone, vinyl acetate, glycidyl (meth) acrylate , (Meta) Acrylate ester copolymer obtained by copolymerizing a monomer component (c) such as (meth) acrylamide, (meth) acrylonitrile, fluorinated (meth) acrylate, and silicone (meth) acrylate. be able to.

The mass average molecular weight of the (meth) acrylic (co) polymer is preferably 100,000 to 1.5 million, particularly preferably 150,000 or more or 1.3 million or less, and particularly preferably 200,000 or more or 1.2 million or less.

When a pressure-sensitive adhesive composition having a high cohesive force is desired, the mass average molecular weight is 700,000 to 1.5 million, particularly 800,000 or more or 1.3 million or less, from the viewpoint that the larger the molecular weight, the more the cohesive force can be obtained by entanglement of molecular chains. Is preferable. On the other hand, when it is desired to obtain a pressure-sensitive adhesive composition having high fluidity and stress relaxation property, the mass average molecular weight is preferably 70,000 to 700,000, particularly preferably 100,000 or more or 600,000 or less. Further, when a solvent is not used when molding an adhesive sheet or the like, it is difficult to use a polymer having a large molecular weight. Therefore, the mass average molecular weight of the acrylic copolymer is 70,000 to 700,000, especially 100,000 or more. Alternatively, it is preferably 600,000 or less, particularly preferably 150,000 or more or 500,000 or less.

(Acrylic copolymer (A1))
As an example of a preferable base polymer of the present pressure-sensitive adhesive sheet, a (meth) acrylic copolymer (A1) composed of a graft copolymer having a macromonomer as a branch component can be mentioned.

If the adhesive sheet is constructed using the acrylic copolymer (A1) as a base resin, the adhesive sheet can exhibit self-adhesiveness while maintaining a sheet shape at room temperature, and when heated in an uncrosslinked state, it can exhibit self-adhesiveness. It has a hot-melt property that melts or flows, and can be photo-cured, and after photo-curing, it can exhibit excellent cohesive force and adhere.
Therefore, if an acrylic copolymer (A1) is used as the base polymer of the present adhesive sheet, it exhibits adhesiveness at room temperature (20 ° C.) even in an uncrosslinked state, and is more preferably 50 to 90 ° C. Can have the property of softening or fluidizing when heated to a temperature of 60 ° C. or higher or 80 ° C. or lower.

The glass transition temperature of the copolymer constituting the stem component of the acrylic copolymer (A1) is preferably −70 to 0 ° C.
At this time, the glass transition temperature of the copolymer component constituting the stem component refers to the glass transition temperature of the polymer obtained by copolymerizing only the monomer component constituting the stem component of the acrylic copolymer (A1). .. Specifically, it means a value calculated by the Fox calculation formula from the glass transition temperature and the composition ratio of the polymer obtained from the homopolymer of each component of the copolymer.
The Fox calculation formula is a calculation value obtained by the following formula, and is a polymer handbook [Polymer HandBook, J. et al. It can be obtained by using the value described in Brandup, Interscience, 1989].
1 / (273 + Tg) = Σ (Wi / (273 + Tgi))
[In the formula, Wi indicates the weight fraction of the monomer i, and Tgi indicates the Tg (° C.) of the homopolymer of the monomer i. ]

The glass transition temperature of the copolymer component constituting the stem component of the acrylic copolymer (A1) is the flexibility of the adhesive sheet at room temperature and the wettability of the adhesive sheet to the adherend, that is, Since it affects the adhesiveness, the glass transition temperature is preferably −70 ° C. to 0 ° C., particularly −65 ° C., in order for the present adhesive sheet to obtain appropriate adhesiveness (tackiness) at room temperature. More than or equal to −5 ° C. or lower, particularly preferably −60 ° C. or higher or −10 ° C. or lower.
However, even if the glass transition temperature of the copolymer component is the same, the viscoelasticity can be adjusted by adjusting the molecular weight. For example, it can be made more flexible by reducing the molecular weight of the copolymer component.

Examples of the (meth) acrylic acid ester monomer contained in the stem component of the acrylic copolymer (A1) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and isopropyl (meth) acrylate. n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, neopentyl (meth) acrylate, hexyl ( Meta) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate , Decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, behenyl (meth) acrylate, Isobornyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, 3,5,5-trimethylcyclohexane acrylate, p-cumylphenol EO modified (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl ( Examples thereof include meta) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and benzyl (meth) acrylate. These include hydroxyl group-containing (meth) acrylates such as hydroxyethyl (meth) acrylates, hydroxypropyl (meth) acrylates, hydroxybutyl (meth) acrylates, and glycerol (meth) acrylates having hydrophilic groups and organic functional groups, and (meth) acrylates. ) Acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxypropyl hexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxypropylphthalic acid Acids, 2- (meth) acryloyloxyethyl maleic acid, 2- (meth) acryloyloxypropyl maleic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxypropyl succinic acid, crotonic acid, fumal Carboxyl group-containing monomers such as acid, maleic acid, itaconic acid, monomethyl maleate, monomethyl itaconate, acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride, glycidyl (meth) acrylate, α-ethylacrylic acid. Epoxy group-containing monomers such as glycidyl and 3,4-epoxybutyl (meth) acrylic acid, amino group-containing (meth) acrylic acid ester-based monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate, (meth). ) Acrylate, N-t-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone acrylamide, maleic acid amide, maleimide, etc. A monomer containing an amide group, a heterocyclic basic monomer such as vinylpyrrolidone, vinylpyridine, vinylcarbazole and the like can also be used.
In addition, styrene, t-butyl styrene, α-methyl styrene, vinyl toluene, acrylonitrile, methacrylonitonyl, vinyl acetate, vinyl propionate, alkyl vinyl ether, hydroxyalkyl vinyl ether, alkyl, which can be copolymerized with the above acrylic monomer and methacrylic monomer. Various vinyl monomers such as vinyl monomers can also be used as appropriate.

Further, the stem component of the acrylic copolymer (A1) preferably contains a hydrophobic (meth) acrylate monomer and a hydrophilic (meth) acrylate monomer as constituent units.
When the stem component of the acrylic copolymer (A1) is composed of only hydrophobic monomers, there is a tendency for moist heat bleaching. Therefore, it is preferable to introduce hydrophilic monomers into the stem components to prevent moist heat bleaching. ..

Specifically, as the stem component of the acrylic copolymer (A1), a hydrophobic (meth) acrylate monomer, a hydrophilic (meth) acrylate monomer, and a polymerizable functional group at the end of the macromonomer are included. Examples thereof include copolymer components obtained by random copolymerization.

Here, examples of the hydrophobic (meth) acrylate monomer include n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, and pentyl (meth). ) Acrylate, isopentyl (meth) acrylate, neopentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, nonyl (meth) ) Acrylate, isononyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl ( Examples thereof include meta) acrylate, isostearyl (meth) acrylate, behenyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylicate, and methyl methacrylate.
Examples of the hydrophobic vinyl monomer include vinyl acetate, styrene, t-butyl styrene, α-methyl styrene, vinyl toluene, and alkyl vinyl monomer.

Examples of the hydrophilic (meth) acrylate monomer include methyl acrylate, (meth) acrylic acid, tetrahydrofurfuryl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) butyl. ) Acrylate, hydroxyl group-containing (meth) acrylate such as glycerol (meth) acrylate, (meth) acrylic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxypropyl hexahydrophthalic acid, 2- (Meta) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxypropylphthalic acid, 2- (meth) acryloyloxyethyl maleic acid, 2- (meth) acryloyloxypropylmaleic acid, 2- (meth) acryloyl Oxyethyl succinic acid, 2- (meth) acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, monomethyl maleate, monomethyl itaconate and other carboxyl group-containing monomers, maleic anhydride, itaconic anhydride, etc. Acid anhydride group-containing monomer, glycidyl (meth) acrylate, glycidyl α-ethyl acrylate, epoxy group-containing monomer such as 3,4-epoxybutyl (meth) acrylate, alkoxy such as methoxypolyethylene glycol (meth) acrylate Examples thereof include polyalkylene glycol (meth) acrylate, N, N-dimethylacrylamide, hydroxyethylacrylamide and the like.

(Branch component: macromonomer)
It is preferable that the acrylic copolymer (A1) contains a repeating unit derived from a macromonomer by introducing a macromonomer as a branch component of the graft copolymer.
The macromonomer is a polymer monomer having a polymerizable functional group at the terminal and a high molecular weight skeleton component.

The glass transition temperature (Tg) of the macromonomer is preferably higher than the glass transition temperature of the copolymer component constituting the acrylic copolymer (A1).
Specifically, since the glass transition temperature (Tg) of the macromonomer affects the heating and melting temperature (hot melt temperature) of the adhesive sheet, the glass transition temperature (Tg) of the macromonomer is 30 ° C. to 120 ° C. The temperature is preferably 40 ° C. or higher or 110 ° C. or lower, and more preferably 50 ° C. or higher or 100 ° C. or lower.
With such a glass transition temperature (Tg), by adjusting the molecular weight, excellent processability and storage stability can be maintained, and the temperature can be adjusted so as to hot melt at around 50 ° C. to 80 ° C. ..
The glass transition temperature of the macromonomer refers to the glass transition temperature of the macromonomer itself, and can be measured with a differential scanning calorimeter (DSC).

Further, in a room temperature state, it is possible to maintain a state in which the branch components are attracted to each other and physically cross-linked as an adhesive composition, and the physical cross-linking is released by heating to an appropriate temperature. It is also preferable to adjust the molecular weight and content of the macromonomer so that the fluidity can be obtained.
From this point of view, the macromonomer is preferably contained in the acrylic copolymer (A1) in a proportion of 5% by mass to 30% by mass, particularly 6% by mass or more or 25% by mass or less, and 8% by mass among them. It is preferably more than or less than 20% by mass.
The number average molecular weight of the macromonomer is preferably 500 or more and less than 8000, and more preferably 800 or more or less than 7500, and more preferably 1000 or more or less than 7000.
As the macromonomer, a generally produced one (for example, a macromonomer manufactured by Toagosei Co., Ltd.) can be appropriately used.

The high molecular weight skeleton component of the macromonomer is preferably composed of an acrylic polymer or a vinyl polymer.
Examples of the high molecular weight skeleton component of the macromonomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth) acrylate. , Se-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, neopentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) ) Acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, Undecyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, behenyl (meth) acrylate, isobornyl (meth) acrylate, 2-phenoxyethyl (meth) Acrylate, 3,5,5-trimethylcyclohexane acrylate, p-cumylphenol EO modified (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate , Benzyl (meth) acrylate, hydroxyalkyl (meth) acrylate, (meth) acrylic acid, glycidyl (meth) acrylate, (meth) acrylamide, N, N-dimethyl (meth) acrylamide, (meth) acrylic nitrile, alkoxyalkyl ( (Meta) acrylate monomers such as meta) acrylates and alkoxypolyalkylene glycol (meth) acrylates, styrene, t-butyl styrene, α-methyl styrene, vinyl toluene, alkyl vinyl monomers, alkyl vinyl esters, alkyl vinyl ethers, hydroxyalkyl vinyl ethers. These include various vinyl monomers such as, etc., which can be used alone or in combination of two or more.

Examples of the terminal polymerizable functional group of the macromonomer include a methacryloyl group, an acryloyl group, and a vinyl group.

[Crosslinking agent (B)]
The cross-linking agent (B) is selected from, for example, a (meth) acryloyl group, an epoxy group, an isocyanate group, a carboxyl group, a hydroxyl group, a carbodiimide group, an oxazoline group, an aziridine group, a vinyl group, an amino group, an imino group and an amide group. A cross-linking agent having at least one kind of cross-linking functional group can be mentioned, and one kind or a combination of two or more kinds may be used.
The crosslinkable functional group may be protected by a deprotectable protecting group.

Examples of such polyfunctional (meth) acrylates include 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, glycerin di (meth) acrylate, and glycering ricidyl ether di (meth) acrylate. 1,6-Hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, tricyclodecanedimethanol di (meth) acrylate, bisphenol A polyethoxydi (meth) acrylate, bisphenol A polyalkoxydi (meth) ) Acrylate, Bisphenol F polyalkoxydi (meth) acrylate, Polyalkylene glycol di (meth) acrylate, Trimethylolpropantrioxyethyl (meth) acrylate, ε-caprolactone-modified tris (2-hydroxyethyl) isocyanurate tri (meth) Acrylate, pentaerythritol tri (meth) acrylate, propoxylated pentaerythritol tri (meth) acrylate, ethoxylated pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, propoxylated pentaerythritol tetra (meth) acrylate, ethoxylated Pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, polyethylene glycol di (meth) acrylate, tris (acryloxyethyl) isocyanurate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate , Dipentaerythritol penta (meth) acrylate, tripentaerythritol hexa (meth) acrylate, trypentaerythritol penta (meth) acrylate, neopentyl glycol di (meth) acrylate of hydroxybivariate, ε of neopenglycol hydroxybivariate -A UV-curable polyfunctional monomers such as di (meth) acrylates of caprolactone adducts, trimethylol propanetri (meth) acrylates, alkoxylated trimethylol propanetri (meth) acrylates, and ditrimethylol propanetetra (meth) acrylates. In addition to polyfunctional acrylic oligomers such as polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, and polyether (meth) acrylate, polyfunctional acrylamide and the like can be used. Can be mentioned.

Among the above-mentioned polyfunctional (meth) acrylic acid ester monomers, polar functional groups such as hydroxyl groups, carboxyl groups, and amide groups are among the above-mentioned polyfunctional (meth) acrylic acid ester monomers from the viewpoint of improving the adhesion to the adherend and the effect of suppressing moist heat bleaching. A polyfunctional monomer or oligomer containing the above is preferable. Among them, it is preferable to use a polyfunctional (meth) acrylic acid ester having a hydroxyl group or an amide group.
From the viewpoint of preventing moist heat bleaching, the (meth) acrylic acid ester copolymer (A1), that is, a hydrophobic acrylate monomer and a hydrophilic acrylate monomer are contained as a stem component of the graft copolymer. Further, it is preferable to use a polyfunctional (meth) acrylic acid ester having a hydroxyl group as the cross-linking agent (B).
Further, a monofunctional or polyfunctional (meth) acrylic acid ester that reacts with the cross-linking agent (B) may be further added in order to adjust the effects such as adhesion, moisture heat resistance, and heat resistance.

The content of the cross-linking agent (B) is 0.1 to 20 with respect to 100 parts by mass of the (meth) acrylic copolymer (A) from the viewpoint of balancing the flexibility and cohesive force of the pressure-sensitive adhesive composition. It is preferably contained in a proportion of parts by mass, particularly preferably 0.5 parts by mass or more or 15 parts by mass or less, and particularly preferably 1 part by mass or more or 13 parts by mass or less.

[Photopolymerization Initiator (C)]
The photopolymerization initiator (C) used in the present pressure-sensitive adhesive sheet functions as a reaction initiation aid in the cross-linking reaction of the cross-linking agent (B), and is used for visible light, for example, light in the wavelength region of 380 nm to 700 nm. Those that generate radicals by irradiation and serve as the starting point of the polymerization reaction of the base resin are preferable. However, radicals may be generated only by irradiation with visible light, or radicals may be generated by irradiation with light in a wavelength region other than the visible light region.

From this point of view, the photopolymerization initiator (C) has an extinction coefficient of 10 mL / (g · cm) or more at a wavelength of 405 nm, particularly 15 mL / (g · cm) or more, and 25 mL / (g · cm) or more among them. Those are particularly preferable.
The extinction coefficient in the present invention corresponds to the absorbance at an optical path length of 1 cm when the photopolymerization initiator is a methanol solution having a concentration of 1 g / L.

Examples of the photopolymerization initiator having an absorption coefficient of 10 mL / (g · cm) or more at a wavelength of 405 nm include 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butane-1-one, 2-( 4-methylbenzyl) -2-dimethylamino-1- (4-morpholinophenyl) butan-1-one, bis (eta ^{5-2,4-cyclopentadiene-1-yl)} - bis (2,6-difluoro -3- (1H-pyrrole-1-yl) phenyl) titanium, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4) , 6-trimethylbenzoyl) ethoxyphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) 2,4,4-trimethylpentylphosphine oxide, thioxanthone, 2-chlorothioxanthone, 3-methylthioxanthone, 2,4-dimethylthioxanthone , Anthraquinone, 2-Methylanthraquinone, 2-Ethylanthraquinone, 2-tert-butylanthraquinone, 2-Aminoanthraquinone, 1,2-octanedione, 1- (4- (phenylthio), 2- (o-benzoyloxime)) , 1- [9-ethyl-6- (2-methylbenzoyl) -9H-carbazole-3-yl] -etanone 1- (O-acetyloxime), camphorquinone, triazine-based photopolymerization initiator, etc. be able to.
As these, any one of these or a derivative thereof may be used, or two or more of these may be used in combination. Further, it may be used in combination with a photopolymerization initiator having an extinction coefficient of less than 10 mL / (g · cm) at a wavelength of 405 nm.

Photopolymerization initiators are roughly classified into two types according to the radical generation mechanism: a cleavage-type photopolymerization initiator capable of cleaving and decomposing a single bond of the photopolymerization initiator itself to generate radicals, and a photoexcited initiator. And the hydrogen donor in the system form an excitation complex, which is roughly classified into a hydrogen abstraction type photopolymerization initiator capable of transferring the hydrogen of the hydrogen donor.
Of these, the cleavage-type photopolymerization initiator decomposes to another compound when a radical is generated by light irradiation, and once excited, it loses its function as a reaction initiator. Therefore, when the intramolecular cleavage type is used as the photopolymerization initiator (C) having an absorption wavelength in the visible light region, the pressure-sensitive adhesive sheet is crosslinked by light irradiation and then the light reaction is performed as compared with the case where the hydrogen extraction type is used. It is preferable because the property photopolymerizable initiator remains as an unreacted residue in the pressure-sensitive adhesive composition, and it is unlikely that the pressure-sensitive adhesive sheet will change over time or promote cross-linking. Further, the coloring peculiar to the photopolymerizable initiator is also preferable because it becomes a reactive decomposition product, so that absorption in the visible light region is eliminated and a decolorizing one can be appropriately selected.
On the other hand, the hydrogen abstraction type photopolymerization initiator does not generate decomposition products like the cleavage type photopolymerization initiator during the radical generation reaction by irradiation with active energy rays such as ultraviolet rays, so that it is less likely to become a volatile component after the reaction is completed, and the subject is subject to Damage to the body can be reduced.

Examples of the cleavage-type photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1-phenyl-propane-1. -On, 1- (4- (2-Hydroxyethoxy) phenyl) -2-hydroxy-2-methyl-1-propane-1-one, 2-Hirodoxy-1- [4- {4- (2-hydroxy-) 2-Methyl-propionyl) benzyl} phenyl] -2-methyl-propane-1-one, oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone), phenylglycioxy Methyl licate, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butane-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1 -On, 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone, bis (2,4,6-trimethylbenzoyl) -Phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl) ethoxyphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) 2,4,4-trimethyl Examples thereof include pentylphosphine oxide and derivatives thereof.

Among these, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphos are the cleaved photopolymerizable initiators in that they become decomposition products and decolorize after the reaction. Acylphosphine oxide-based photoinitiators such as finoxide, (2,4,6-trimethylbenzoyl) ethoxyphenylphosphine oxide, and bis (2,6-dimethoxybenzoyl) 2,4,4-trimethylpentylphosphine oxide are preferred.
Further, from the compatibility with an acrylic copolymer composed of a graft copolymer having a macromonomer as a branch component, 2,4,6-trimethylbenzoyldiphenylphosphine oxide as a photopolymerization initiator (C), (2). , 4,6-trimethylbenzoyl) ethoxyphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) 2,4,4-trimethylpentylphosphine oxide and the like are preferably used.

The content of the photopolymerization initiator (C) is not particularly limited. For example, 0.1 to 10 parts by mass, particularly 0.2 parts by mass or more or 5 parts by mass or less, and 0.5 parts by mass or more or 3 parts by mass among 100 parts by mass of the (meth) acrylic copolymer (A). It is particularly preferable to include a portion or less. However, this range may be exceeded in balance with other factors. The photopolymerization initiator may be used alone or in combination of two or more.

[Ultraviolet absorber (D)]
The ultraviolet absorber (D) may be a substance that can absorb ultraviolet rays, and as a guide, the absorbance of the transparent double-sided pressure-sensitive adhesive sheet at a wavelength of 380 nm is 0.3 or more, especially 0. It is preferably a substance that can be 5 or more, and 1 or more among them.

The absorbance at a wavelength of 380 nm can be obtained from the following formula.
_{A 380 = -Log (T 380/} 100)
A ₃₈₀ : Absorbance at a wavelength of 380 nm
T ₃₈₀ ; Transmittance (%) of transparent double-sided adhesive sheet at 380 nm

As the ultraviolet absorber (D), for example, one or more structures selected from the group consisting of a benzotriazole structure, a benzophenone structure, a triazine structure, a benzoate structure, an oxalanilide structure, a salicylate structure and a cyanoacrylate structure may be used. It is preferable to have.
Among them, those having one or two or more structures selected from the group consisting of a benzotriazole structure, a triazine structure and a benzophenone structure are preferable from the viewpoint of ultraviolet absorption.
Further, from the viewpoint of compatibility with an acrylic copolymer composed of a graft copolymer having a macromonomer as a branch component, it is preferable to use a benzotriazole structure or a benzophenone structure as the ultraviolet absorber (D).

The content of the ultraviolet absorber (D) is not particularly limited. For example, 0.01 to 10 parts by mass, particularly 0.1 parts by mass or more or 5 parts by mass or less, and 0.2 parts by mass or more or 3 parts by mass among 100 parts by mass of the (meth) acrylic copolymer (A). It is particularly preferable to contain the content in a proportion of parts or less. However, this range may be exceeded in balance with other factors.

From the viewpoint of absorbing ultraviolet rays and initiating photopolymerization in the visible light region excluding the ultraviolet rays, the ratio of the ultraviolet absorber (D) to 100 parts by mass of the photopolymerization initiator (C) is 25 to 400 parts by mass. It is preferably 50 parts by mass or more or 300 parts by mass or less, and particularly preferably 80 parts by mass or more or 250 parts by mass or less. The ultraviolet absorber may be used alone or in combination of two or more.

[Other ingredients]
As a component other than the above, the pressure-sensitive adhesive sheet may contain a known component that is blended in a normal pressure-sensitive adhesive composition. For example, tackifying resins, antioxidants, light stabilizers, metal deactivators, rust inhibitors, anti-aging agents, hygroscopic agents, hydrolysis inhibitors, sensitizers, antistatic agents, defoamers, etc. It is possible to appropriately contain various additives such as inorganic particles.
Further, if necessary, a reaction catalyst (tertiary amine compound, quaternary ammonium compound, tin laurate compound, etc.) may be appropriately contained.

[Preferable composition example]
As an example of a particularly preferable composition of the present pressure-sensitive adhesive composition, the (meth) acrylic copolymer (A) contains an acrylic copolymer composed of a graft copolymer having a macromonomer as a branch component and is crosslinked. The agent (B) contains a polyfunctional (meth) acrylic acid ester compound such as bifunctional and trifunctional, and the photopolymerization initiator (C) contains a cleavage-type photopolymerization initiator, and an ultraviolet absorber (D). ), Examples of the composition containing an ultraviolet absorber having a benzotriazole structure or a benzophenone structure can be mentioned. However, the composition is not limited in this way.

[Laminated structure]
The present adhesive sheet may be a sheet composed of a single layer or a multi-layer sheet in which two or more layers are laminated.
When the present pressure-sensitive adhesive sheet is a multi-layered pressure-sensitive adhesive sheet, that is, when a pressure-sensitive adhesive sheet having a laminated structure including an intermediate layer and an outermost layer is formed, the outermost layer is formed from the present pressure-sensitive adhesive composition. Is preferable.

When the present adhesive sheet has a multi-layer structure, the ratio of the thickness of each outermost layer to the thickness of the intermediate layer is preferably 1: 1 to 1:20, particularly 1: 2 to 1:10. Is even more preferable.
When the thickness of the intermediate layer is within the above range, the contribution of the thickness of the pressure-sensitive adhesive layer in the laminated body does not become too large, and it is preferable that the thickness does not become too flexible and the workability related to cutting and handling is not deteriorated.
Further, when the outermost layer is in the above range, it is preferable that the adhesive force to the adherend and the wettability can be maintained without being inferior in the followability to the uneven or bent surface.

[Sheet thickness]
Regarding the thickness of this adhesive sheet, it is possible to meet the demand for thinning by reducing the sheet thickness, but if the sheet thickness is too thin, for example, if there is an uneven portion on the adherend surface, it will sufficiently follow the unevenness. It may not be possible, or it may not be possible to exert sufficient adhesive strength.
From this point of view, the thickness of the pressure-sensitive adhesive sheet is preferably 20 to 500 μm, particularly preferably 25 μm or more or 350 μm or less, and particularly preferably 50 μm or more or 250 μm or less.

(Characteristic)
The ultraviolet transmittance (JIS K7361-1) of the present adhesive sheet is preferably 50% or less at a wavelength of 380 nm, more preferably 30% or less, and further preferably 10% or less.

<Adhesive sheet laminate>
This adhesive sheet can be used alone as it is. It is also possible to use it by laminating it with other members.

(This adhesive sheet laminate)
For example, a release film can be laminated on one side or both sides of the adhesive sheet to form an adhesive sheet laminate (referred to as "the adhesive sheet laminate").

At this time, it is preferable that one or both release films have a light transmittance of 40% or less for light having a wavelength of 410 nm or less. If at least one of the release films has a light transmittance of 40% or less for light having a wavelength of 410 nm or less, the release film can be laminated on the adhesive sheet to have an absorption coefficient of 10 mL at a wavelength of 405 nm. This is because even if the photopolymerization initiator (C) having a / (g · cm) or more is contained, it is possible to effectively prevent the photopolymerization from proceeding by irradiation with visible light.
From this point of view, one or both release films preferably have a light transmittance of 40% or less for light having a wavelength of 410 nm or less, more preferably 30% or less, and more preferably 20% or less.

Here, as a release film having a light transmittance of 40% or less for light having a wavelength of 410 nm or less, that is, a release film having a function of partially blocking the transmission of visible light and ultraviolet light, for example, an ultraviolet absorber is blended. Examples thereof include cast films and stretched films made of polyester-based, polypropylene-based, and polyethylene-based resins that have been subjected to a mold release treatment by applying a silicone resin. In addition, a multi-layer cast film or stretched film formed by molding a layer made of a resin containing an ultraviolet absorber on one or both sides of a layer made of a polyester-based, polypropylene-based, or polyethylene-based resin containing an ultraviolet absorber. One surface may be coated with a silicone resin and subjected to a mold release treatment. Further, a paint containing an ultraviolet absorber is applied to one surface of a cast film or a stretched film made of polyester-based, polypropylene-based, or polyethylene-based resin to provide an ultraviolet absorbing layer, and a silicone resin is further applied on the ultraviolet absorbing layer. Can be mentioned by applying the above and performing a mold release treatment. Further, a paint containing an ultraviolet absorber is applied to one surface of a cast film or a stretched film made of polyester-based, polypropylene-based, or polyethylene-based resin to provide an ultraviolet absorbing layer, and a silicone resin is applied to the other surface. Examples thereof include those that have been released from the mold. Further, the other surface of the resin film made of polyester-based, polypropylene-based, or polyethylene-based resin whose one surface has been mold-released and the resin film which has not been mold-released separately prepared are adhered to each other containing an ultraviolet absorber. Examples thereof include those laminated via a layer or an adhesive layer.

The release film may have other layers, such as an antistatic layer, a hard coat layer, and an anchor layer, if necessary.
If the thickness of the release film is too thick, the cutting processability is inferior, and if it is too thin, the handling property is inferior, and the adhesive sheet may be easily dented. From this point of view, the thickness of the release film is preferably 20 μm or more and 300 μm or less, particularly preferably 25 μm or more or 250 μm or less, and particularly preferably 38 μm or more or 200 μm or less.
When the release films are laminated on both sides, it is preferable that the thickness and peeling force of one release film and the other release film are different.

Further, as a preferable configuration example, a configuration in which a surface protective film having a light transmittance of 40% or less of light having a wavelength of 410 nm or less is laminated on one side or both sides of the pressure-sensitive adhesive sheet laminate can be mentioned.
By laminating a surface protective film having a light transmittance of 40% or less for light having a wavelength of 410 nm or less on at least one surface of the pressure-sensitive adhesive sheet laminate, the pressure-sensitive adhesive sheet has an absorption coefficient of 10 mL / (g. This is because even if the photopolymerization initiator (C) of cm) or more is contained, it is possible to effectively prevent the photopolymerization from proceeding by irradiation with visible light.
From this point of view, the surface protective film laminated on one or both surfaces of the pressure-sensitive adhesive sheet laminate preferably has a light transmittance of 40% or less for light having a wavelength of 410 nm or less, particularly 30% or less, and 20% or less thereof. The following is more preferable.

Here, examples of the surface protective film having a light transmittance of 40% or less for light having a wavelength of 410 nm or less, that is, the surface protective film having a function of partially blocking the transmission of visible light and ultraviolet light, are polyester-based and polypropylene-based. , A laminated film having an ultraviolet absorbing layer, which is formed by applying a fine adhesive resin having removability on one surface of a polyethylene-based cast film or a stretched film and applying a paint containing an ultraviolet absorber on the other surface. Can be mentioned. In addition, one surface of a polypropylene-based or polyethylene-based cast film or a stretched film may be coated with a slightly adhesive resin having a removability and containing an ultraviolet absorber. In addition, a cast film or a stretched film made of a polyester-based, polypropylene-based, or polyethylene-based resin containing an ultraviolet absorber may be coated with a slightly adhesive resin having removability. In addition, a multi-layer cast film or stretched film formed by molding a layer made of a resin containing no ultraviolet absorber on one or both sides of a layer made of a polyester-based, polypropylene-based, or polyethylene-based resin containing an ultraviolet absorber. One surface coated with a slightly adhesive resin having removability can be mentioned. Further, a paint containing an ultraviolet absorber is applied to one surface of a cast film or a stretched film made of polyester-based, polypropylene-based, or polyethylene-based resin to provide an ultraviolet absorbing layer, and the film is peeled off again on the ultraviolet absorbing layer. Examples thereof include those coated with a slightly adhesive resin having a property. Further, a paint containing an ultraviolet absorber is applied to one surface of a cast film or a stretched film made of polyester-based, polypropylene-based, or polyethylene-based resin to provide an ultraviolet absorbing layer, and the other surface has fine removability. Examples thereof include those coated with an adhesive resin. Further, the other surface of the resin film made of polyester-based, polypropylene-based, or polyethylene-based resin coated with a slightly adhesive resin having removability on one surface and the separately prepared resin film are adhered together with an ultraviolet absorber. Examples thereof include those laminated via a layer or an adhesive layer.
The surface protective film may have other layers, such as an antistatic layer, a hard coat layer, and an anchor layer, if necessary.

(Laminate for configuration of this image display device)
It is also possible to stack two image display device constituent members via the adhesive sheet to form an image display device configuration laminate (referred to as "the image display device configuration laminate"). ..

At this time, examples of the two image display device components include any one of the group consisting of a touch sensor, an image display panel, a surface protection panel, and a polarizing film, or a combination of two or more types.

Specific examples of the laminate for configuring the image display device include a release sheet / main adhesive sheet / touch panel, a release sheet / main adhesive sheet / protective panel, a release sheet / main adhesive sheet / image display panel, and an image display. Panel / book adhesive sheet / touch panel, image display panel / book adhesive sheet / protective panel, image display panel / book adhesive sheet / touch panel / book adhesive sheet / protective panel, polarizing film / book adhesive sheet / touch panel, polarizing film / book adhesive The configuration of the sheet / touch panel / main adhesive sheet / protective panel and the like can be mentioned. However, the present invention is not limited to these laminated examples.
The touch panel also includes a structure having a touch panel function built into the protective panel and a structure having a touch panel function built into the image display panel.

(This image display device)
An image display device (referred to as "the image display device") can be configured by using the adhesive sheet or the laminate for constructing the image display device as described above.
As the image display device, for example, an image display device such as a liquid crystal display, an organic EL display, an inorganic EL display, an electronic paper, a plasma display, and a microelectromechanical system (MEMS) display can be configured.

<Characteristics and usage of this adhesive sheet>
This adhesive sheet has an ultraviolet absorbing function and a curability that cures when irradiated with light having a wavelength other than the ultraviolet region, particularly visible light. Utilizing such characteristics of the pressure-sensitive adhesive sheet, a laminate for forming an image display device can be produced, for example, as follows.

After the present pressure-sensitive adhesive composition is formed into a sheet (sheet manufacturing step), two image display device constituent members are laminated via the present pressure-sensitive adhesive sheet before photocuring (primary attachment step), and then visible light. By irradiating light containing light having a wavelength in the region to photocrosslink and cure the adhesive sheet (secondary attachment step), a laminate for forming an image display device can be produced.
The light containing light having a wavelength in the visible light region may include light having a wavelength in the ultraviolet region, that is, a wavelength of 380 nm or less, but when the laminated image display device constituent member is a member that is easily deteriorated by ultraviolet rays, the wavelength is It is preferable to irradiate a light beam having a wavelength of 380 nm or less, that is, a visible light beam, to photocrosslink the adhesive sheet and cure it (secondary sticking step).

(Sheet manufacturing process)
The present pressure-sensitive adhesive composition can be formed into a sheet to prepare the present pressure-sensitive adhesive sheet.
As a method for molding the present pressure-sensitive adhesive resin composition into a sheet, a currently known method can be arbitrarily adopted.

At this time, as described above, the pressure-sensitive adhesive resin composition may be formed into a sheet on the release film to prepare the pressure-sensitive adhesive sheet.
Further, the pressure-sensitive adhesive resin composition may be formed into a sheet on the image display device component, and the pressure-sensitive adhesive sheet may be laminated on the image display device component.

(Primary attachment process)
If the adhesive sheet has self-adhesiveness (tackiness), it can be primarily attached by simply stacking two image display device constituent members via the adhesive sheet.

For example, if the adhesive sheet is based on an acrylic copolymer (A1) made of a graft copolymer having a macromonomer as a branch component, it self-adhesively keeps the sheet shape at room temperature. Not only can it exhibit properties, but it can also have appropriate adhesiveness, for example, peelable adhesiveness (referred to as "tackiness") in a normal state, that is, near room temperature, in an uncrosslinked state. , It is possible to facilitate positioning at the time of sticking. Furthermore, since it can be melted or flowed when heated in an uncrosslinked state (hot melt property), the adhesive can be filled according to uneven portions such as printing steps, and the adhesive can be filled without generating air bubbles. be able to.

A known device can be used as the laminating device used for laminating. For example, an electric press equipped with a heating plate, a diaphragm type laminator, a roll laminator, a vacuum bonding machine, a hand roll, and the like can be mentioned.

When this adhesive sheet uses an acrylic copolymer (A1) composed of a graft copolymer having a macromonomer as a branch component as a base polymer, it has excellent storage stability in a normal state, that is, in a room temperature state. And cutting workability can be imparted. Moreover, since it has self-adhesiveness (tackiness), it is possible to obtain adhesiveness to the extent that it can be easily attached by simply pressing the adhesive sheet against the adherend. Easy to do and very convenient for work.
Furthermore, since it has excellent shape retention, it can be processed into an arbitrary shape in advance. Therefore, the size of the image display device component to which the present adhesive sheet molded on the release film is laminated is adjusted. It can also be cut in advance.
The cutting method at this time is generally punching with a Thomson blade, cutting with a super cutter or laser, and half-cutting leaving either the front or back release film in a frame shape so that the release film can be easily peeled off. Is more preferable.

If the adhesive sheet has a hot-melt property, that is, a property of being softened or fluidized by heating, even if the adherend surface has irregularities, the adhesive sheet is heated to follow the irregularities. Even unevenness can be filled without gaps.
At this time, as the heating means of the adhesive sheet, for example, various constant temperature baths, a hot plate, an electromagnetic heating device, a heating roll, or the like can be used. For more efficient bonding and heating, for example, an electric press, a diaphragm type laminator, a roll laminator, or the like is preferably used.

At this time, if the softening temperature of the pressure-sensitive adhesive sheet is 50 ° C. or higher, the processing characteristics and the storage characteristics at room temperature can be sufficiently satisfied. On the other hand, if the softening temperature of the adhesive sheet is 100 ° C. or lower, not only can the heat damage to the image display panel and the front panel be suppressed, but also the adhesive sheet can be prevented from flowing out too much. it can.
Therefore, the softening temperature of the pressure-sensitive adhesive sheet is preferably 50 to 100 ° C., more preferably 55 ° C. or higher or 95 ° C. or lower, and more preferably 60 ° C. or higher or 90 ° C. or lower.

When heating the pressure-sensitive adhesive sheet, it is preferable to stack the two image display device constituent members on top of each other via the pressure-sensitive adhesive sheet, and then heat the laminated body in a reduced pressure environment.
By heating the laminate in a reduced pressure environment, it is possible to prevent air bubbles and foreign substances from being mixed into the adhesive sheet after bonding.

(Secondary attachment process)
In the secondary sticking step, the image display device constituent member is laminated from the outside of at least one image display device constituent member on the laminated body formed by laminating the two image display device constituent members via the adhesive sheet. The adhesive sheet is irradiated with light containing light having a wavelength in the visible light region, preferably light having a wavelength of 380 nm or less, that is, visible light, and the adhesive sheet is photocrosslinked and cured. ..

By photocrosslinking in this way, the present adhesive sheet can be firmly crosslinked, so that the adhesive strength is sufficient to sufficiently counter the gas pressure of the outgas generated from the image display device constituent members such as the protective panel. It can have a cohesive force. Moreover, since the present adhesive sheet has ultraviolet absorption, it is possible to suppress deterioration of the adhesive sheet itself and the image display device constituent members due to ultraviolet rays.

When irradiating visible light, it is preferable to irradiate visible light that does not substantially contain light having a wavelength in the ultraviolet region, for example, light having a wavelength less than 365 nm.
Here, "substantially free of light having a wavelength of less than 365 nm" means that the emission intensity of light having a wavelength of less than 365 nm is less than 1 mW / cm ^2.

As a method of irradiating visible light that does not contain light having a wavelength in the ultraviolet region, as described above, a light source that emits only visible light that does not contain light having a wavelength in the ultraviolet region may be used.
Examples of the light source that emits only visible light include fluorescent lamps, LEDs, organic ELs, and inorganic ELs.
Further, the irradiation may be performed through a filter that does not transmit light having a wavelength in the ultraviolet region. For example, a high-pressure mercury lamp, a metal halide lamp, a xenon arclamp, a carbon arc lamp, or the like that emits light having a wavelength in the ultraviolet region, or sunlight is used as a light source, and the light transmittance at a wavelength of 380 nm is less than 10%. A method of irradiating the adhesive composition with visible light through a filter having a wavelength of 405 nm and a light transmittance of 60% or more can be mentioned.
The filter may be a release film constituting the present pressure-sensitive adhesive sheet laminate or a surface protection film used by being laminated on the surface of the present pressure-sensitive adhesive sheet laminate.

In order to adjust the degree of visible light cross-linking, in addition to the method of controlling the irradiation amount of visible light, visible light is irradiated through the filter so as to partially block the transmission of visible light. It is also possible to adjust the degree of cross-linking.

<Explanation of words and phrases>
In general, a "sheet" is a thin product according to the definition in JIS, and its thickness is small for its length and width, and is flat. Generally, a "film" is compared with its length and width. A thin flat product with an extremely small thickness and an arbitrarily limited maximum thickness, which is usually supplied in the form of a roll (Japanese Industrial Standard JIS K6900). However, the boundary between the sheet and the film is not clear, and it is not necessary to distinguish between the two in the present invention. Therefore, in the present invention, even when the term "film" is used, the term "sheet" is included and the term "sheet" is used. Even if it is, it shall include "film".
Further, when the term "panel" is used, such as an image display panel or a protective panel, it includes a plate body, a sheet, and a film.

In the present specification, when "X to Y" (X, Y are arbitrary numbers) is described, it means "X or more and Y or less" and "preferably larger than X" or "preferably larger than X" unless otherwise specified. It also includes the meaning of "smaller than Y".
Further, when described as "X or more" (X is an arbitrary number), it includes the meaning of "preferably larger than X" and is described as "Y or less" (Y is an arbitrary number). In this case, unless otherwise specified, it also includes the meaning of "preferably smaller than Y".

Hereinafter, the description will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited thereto.

The integrated light amount of light at a wavelength of 405 nm and a wavelength of 365 nm measured in this example was measured using an integrated light meter (UIT-250, manufactured by Ushio, Inc.).

[Example 1]
As the (meth) acrylic copolymer (A), a copolymer composed of 15 parts by mass of polymethylmethacrylate macromonomer (Tg80 ° C.) having a number average molecular weight of 3000, 81 parts by mass of butyl acrylate, and 4 parts by mass of acrylic acid. (A-1, mass average molecular weight 300,000) 100 g of glycerin dimethacrylate (Blemmer GMR manufactured by Nichiyu Co., Ltd.) (B-1) as a cross-linking agent (B) and EzaCure KTO46 as a photopolymerization initiator (C) with respect to 1 kg. (C-1) (manufactured by Polymerti) 15 g, 2,6-diphenyl-4- (2-hydroxy-4-hexyloxyphenyl) -1,3,5-triazine (BASF) as an ultraviolet absorber (D) , Tinubin 1577) (D-1) was added in an amount of 5 g, and the mixture was uniformly mixed to obtain an adhesive composition 1.
Extinction coefficient at 405nm of the photopolymerization initiator (C-1) was a ^{7.4 × 10 1 (mL / (} g · cm)).

Next, the pressure-sensitive adhesive composition 1 was formed into a sheet on a peel-treated polyethylene terephthalate film (manufactured by Mitsubishi Plastics, Diafoil MRV, thickness 100 μm) so as to have a thickness of 100 μm, and then peel-treated polyethylene. A terephthalate film (manufactured by Mitsubishi Plastics, Diafoil MRQ, thickness 75 μm) was coated to prepare an adhesive sheet laminate 1.

[Example 2]
As the (meth) acrylic copolymer (A), 10 parts by mass of polymethylmethacrylate macromonomer (Tg55 ° C.) having a number average molecular weight of 1400 and 90 parts by mass of 2-ethylhexyl acrylate (Tg: -70 ° C.) were randomly co-produced. 1 kg of polymerized acrylic graft copolymer (A-2) (weight average molecular weight: 230,000) and tricyclodecanedimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name: DCP) as a cross-linking agent (B) ( B-2) 50 g, Irgacure 369 (C-2) (manufactured by BASF) as a photopolymerization initiator (C), 15 g, and 2- (2H-benzotriazole-2-yl) -4 as an ultraviolet absorber (D). , 6-Di-tert-pentylphenol (manufactured by Johoku Chemical Co., Ltd., JF-80) (D-2) was uniformly mixed to prepare an adhesive resin composition 2.

Next, the pressure-sensitive adhesive composition 4 was applied to a peel-treated polyethylene terephthalate film (manufactured by Mitsubishi Resin Co., Ltd., Diafoil MRV, thickness 100 μm) so as to have a thickness of 100 μm, and then the peel-treated polyethylene terephthalate film (Mitsubishi). A pressure-sensitive adhesive sheet laminate 2 was prepared by coating with a dia foil MRQ manufactured by Resin Co., Ltd. (thickness 75 μm).
The extinction coefficient of the photopolymerization initiator (C-2) at 405 nm was 1.6 × 10 ² (mL / (g · cm)).

[Example 3]
As the (meth) acrylic copolymer (A), a copolymer composed of 76 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of vinyl acetate, and 4 parts by mass of acrylic acid (A-3, mass average molecular weight 400,000). 200 g of propoxylated pentaerythritol tetraacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., ATM-4P) (B-3) as a cross-linking agent (B) and Irgacure 819 (C-3) as a photopolymerization initiator (C-3) with respect to 1 kg. Add 7 g (manufactured by BASF) and 10 g of 2,2'-dihydroxy-4-methoxybenzophenone (Kemipro Kasei Co., Ltd., Kemisorb111) (D-3) as an ultraviolet absorber (D) and mix them uniformly to prepare an adhesive composition. I got 3.
Extinction coefficient at 405nm of the photopolymerization initiator (C-3) was ^{9.0 × 10 2 (mL / (} g · cm)).

The adhesive resin composition 3 was sandwiched between two stripped polyethylene terephthalate films (Mitsubishi Plastics, Diafoil MRF, thickness 75 μm / Mitsubishi Plastics, Diafoil MRT, thickness 38 μm) to a thickness of 100 μm. A sheet for the intermediate layer (α) was prepared by shaping it into a sheet so as to be.

L as an isocyanate-based cross-linking agent for 1 kg of a pressure-sensitive adhesive solution (manufactured by Soken Kagaku Co., Ltd., SK Dyne 1882, solid content concentration: about 17%) composed of a commercially available acrylic copolymer (A-4, mass average molecular weight 1.3 million). Addition of 1.85 g of −45 (B-5) (manufactured by Soken Kagaku Co., Ltd.) and 0.5 g of E-5XM (B-6) (manufactured by Soken Kagaku Co., Ltd.) as an epoxy-based cross-linking agent, the pressure-sensitive adhesive composition 4 Was prepared.
After applying the coating liquid for the adhesive layer on the peeled polyethylene terephthalate film (manufactured by Mitsubishi Plastics, Diafoil MRV, thickness 100 μm) so that the film thickness after drying is 20 to 30 μm. , 80 ° C. for 5 minutes. This was cured at 23 ° C. for 7 days to react with a cross-linking agent to prepare a sheet (β) for an adhesive layer.
Further, the pressure-sensitive adhesive composition 4 is similarly adhered onto the peeled polyethylene terephthalate film (manufactured by Mitsubishi Plastics, Diafoil MRQ, thickness 75 μm) so that the film thickness after drying is 20 to 30 μm. After applying the coating liquid for layering, it was dried at 80 ° C. for 5 minutes. This was cured at 23 ° C. for 7 days to react with a cross-linking agent to prepare a sheet for an adhesive layer (β').

The PET films on both sides of the intermediate layer resin sheet (α) are sequentially peeled off, and the adhesive surfaces of the adhesive layer resin sheets (β) and (β') are sequentially attached to both surfaces of the intermediate layer sheet (α). In combination, a laminate (thickness 150 μm) composed of (β) / (α) / (β') was prepared.

(Beta) and through the PET film remaining on the surface of the (beta '), integrated light quantity 1000 mJ / cm ² with a wavelength of 365 nm, the light at a high pressure mercury lamp as the accumulated light quantity of the wavelength 405nm is 1400mJ / cm ² After irradiation, the intermediate layer resin sheet (α) was photocrosslinked to prepare an adhesive sheet laminate 3.

[Example 4]
Example 1 except that a release film obtained by applying a silicone release agent to a PET film containing an ultraviolet absorber (thickness 100 μm) was used instead of the peeled polyethylene terephthalate film (diafoil MRV, thickness 100 μm). In the same manner as above, the adhesive sheet laminate 4 was prepared.

[Example 5]
A surface composed of a slightly adhesive layer (5 μm) / polyethylene terephthalate film (25 μm) / ultraviolet absorbing layer (3 μm) on the surface of the polyethylene terephthalate film (diafoil MRV, thickness 100 μm) of the pressure-sensitive adhesive sheet laminate prepared in Example 1. The slightly adhesive layer surfaces of the protective film were laminated to prepare an adhesive sheet laminate 5 having a structure of a release film / adhesive sheet / release film / surface protective film.

[Comparative Example 1]
An adhesive sheet laminate 6 was prepared in the same manner as in Example 1 except that 15 g of EzaCure TZT (C-5) was added instead of EzaCure KTO46 (C-1) as a photopolymerization initiator.
The extinction coefficient of the photopolymerization initiator (C-5) at 405 nm was less than 10 (mL / (g · cm)), which was too low to measure.

[Comparative Example 2]
The pressure-sensitive adhesive sheet laminate 7 was prepared in the same manner as in Example 2 except that the ultraviolet absorber (D-2) was not added.

[Comparative Example 3]
L as an isocyanate-based cross-linking agent for 1 kg of a pressure-sensitive adhesive solution (manufactured by Soken Kagaku Co., Ltd., SK Dyne 1882, solid content concentration: about 17%) composed of a commercially available acrylic copolymer (A-4, mass average molecular weight 1.3 million). 1.85 g of -45 (B-5) (manufactured by Soken Kagaku Co., Ltd.), 0.5 g of E-5XM (B-6) (manufactured by Soken Kagaku Co., Ltd.) as an epoxy-based cross-linking agent, and ultraviolet rays as an ultraviolet absorber (D). As an absorbent (D), 10 g of 2,2'-dihydroxy-4-methoxybenzophenone (Kemisorb111, manufactured by Chemipro Kasei Co., Ltd.) (D-3) was added and uniformly mixed to prepare a pressure-sensitive adhesive composition 7.

Next, the pressure-sensitive adhesive composition was applied onto a peel-treated polyethylene terephthalate film (manufactured by Mitsubishi Plastics, Diafoil MRV, thickness 100 μm) so that the thickness after drying was 50 μm, and then at 80 ° C. The mixture was dried for 5 minutes to obtain a sheet-shaped pressure-sensitive adhesive composition 7 having a thickness of 50 μm.
Similarly, it was applied on a stripped polyethylene terephthalate film (manufactured by Mitsubishi Plastics, Diafoil MRQ, thickness 75 μm) so that the thickness after drying was 50 μm, and then dried at 80 ° C. for 5 minutes to achieve the thickness. A sheet-shaped pressure-sensitive adhesive composition 7 having a thickness of 50 μm was obtained. After laminating these to make a thickness of 100 μm, a peel-treated polyethylene terephthalate film (manufactured by Mitsubishi Plastics, Diafoil MRQ, thickness of 75 μm) was coated. This was cured at room temperature (23 ° C.) for 7 days to react with a cross-linking agent to prepare an adhesive sheet laminate 8.

<Evaluation>
[optical properties]
The PET films on both sides of the pressure-sensitive adhesive sheet laminates produced in Examples and Comparative Examples were sequentially peeled off, and the pressure-sensitive adhesive sheets were attached so as to be sandwiched between two soda lime glasses (thickness 0.5 mm) and autoclaved (70 ° C.). , Gauge pressure 0.2 MPa, 20 minutes) was applied to finish and paste. The adhesive sheet laminates 1, 2, 4, 5, 6 and 7 are irradiated with light using a high-pressure mercury lamp via a UV cut filter so that the integrated light amount at a wavelength of 405 nm is 3000 mJ / cm ^2, and the optical characteristics are achieved. An evaluation sample was created.

The light transmittance of the prepared test piece in the wavelength range of 360 to 430 nm was measured with a spectrophotometer (manufactured by Shimadzu Corporation; device name "UV2450").
Those having a light transmittance of less than 50% at 380 nm were judged to be UV-absorbing "good", and those having a light transmittance of 50% or more were judged to be UV-absorbing "x (poor)". The results are shown in Table 1.

[Adhesive force]
For the adhesive sheets produced in Examples and Comparative Examples, one of the release films was peeled off, and a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd .; trade name "Cosmo Shine A4300", thickness 100 μm) was roll-pressed with a hand roller as a backing film. did. This was cut into strips having a width of 10 mm and a length of 100 mm, the remaining release film was peeled off, and the exposed adhesive surface was rolled and attached to soda lime glass using a hand roller. After applying autoclave treatment (70 ° C., gauge pressure 0.2 MPa, 20 minutes) for finishing and pasting, the adhesive sheet laminates 1, 2, 4, 5, 6 and 7 are subjected to high-pressure mercury through a UV cut filter. using lamps, integrated light quantity of 3000 mJ / cm ² with a wavelength of 405 nm, cumulative light quantity of wavelength 365nm is irradiated with visible light so as to be 5 mJ / cm ² or less to prepare a pressure-sensitive adhesive strength measurement sample.

The adhesive sheet is peeled from the glass while pulling the backing film at an angle of 180 ° at a peeling speed of 60 mm / min, and the tensile strength is measured with a load cell to determine the 180 ° peel strength (N / cm) of the adhesive sheet with respect to the glass. It was measured and shown as "glass adhesive strength" in Table 1. The results are shown in Table 1.

[Concavo-convex absorption]
A glass plate 1 with a printing step of 52 mm × 80 mm is prepared by printing 20 μm on the peripheral edge of glass (3 mm on the long side and 15 mm on the short side) of 58 mm × 110 mm × 0.8 mm in thickness. did.
Further, a glass plate 2 having a printing step of 58 mm × 110 mm × 0.8 mm in thickness is printed with a thickness of 10 μm on the peripheral edge (3 mm on the long side and 15 mm on the short side) and the opening is 52 mm × 80 mm. Prepared.
One of the release films of the pressure-sensitive adhesive sheet laminate was peeled off and rolled and bonded to soda lime glass having a thickness of 54 mm × 82 mm and a thickness of 0.5 mm.
Next, the remaining release film is peeled off, and the printing surfaces of the glass plates 1 and 2 with printing steps are press-pressed using a vacuum press so that the four sides of the adhesive surface are applied to the printing steps (absolute pressure 5 kPa, temperature). 70 ° C., press pressure 0.04 MPa), autoclave treatment (70 ° C., gauge pressure 0.2 MPa, 20 minutes) was applied to finish and paste. For the adhesive sheet laminates 1, 2, 4, 5, 6 and 7, the integrated light intensity at a wavelength of 405 nm was 3000 mJ / cm ^{2 from the printed glass side using a high-pressure mercury lamp via a UV cut filter.} A sample for evaluation was prepared by irradiating with light so as to become.

Regarding the evaluation sample, the one that was able to be bonded without air bubbles near the step of the 20 μm printed stepped glass plate 1 was “◎ (excellent)”, and the 10 μm printed stepped glass plate 2 was near the step. Those that could be bonded without bubbles were judged to have unevenness absorption "○ (good)", and those in which bubbles were observed in the vicinity of the steps of the printed glass 1 and 2 were judged to be unevenness absorption "x (poor)". The results are shown in Table 1.

[Heat-resistant]
The release film on one side of the adhesive sheet prepared in Examples and Comparative Examples was peeled off, and a COP film (100 μm manufactured by Nippon Zeon Corporation) was attached to the exposed surface with a hand roller. Next, after cutting out the adhesive sheet to 50 mm × 80 mm, the remaining release film is peeled off, attached to soda lime glass having a thickness of 0.5 mm with a hand roller, and autoclaved (temperature 80 ° C., atmospheric pressure 0). .4 MPa, 30 minutes) was applied. For the adhesive sheet laminates 1, 2, 4, 5, 6 and 7, light is irradiated from the COP surface using a high-pressure mercury lamp via a UV cut filter so that the integrated light amount at a wavelength of 405 nm is 3000 mJ / cm ^2. Then, a sample for evaluation was created.

The evaluation sample was cured at 85 ° C. for 6 hours, and the one with no change in appearance without foaming was heat-resistant "○ (good)", and the one with foaming or peeling was heat-resistant "x (x). poor) ”was judged. The results are shown in Table 1.

[Light resistance]
One of the release films of the pressure-sensitive adhesive sheet laminate was peeled off and rolled and bonded to soda lime glass having a thickness of 150 mm × 200 mm and a thickness of 2 mm. Next, the remaining release film was peeled off, and the exposed adhesive surface was rolled and bonded to soda lime glass having a thickness of 150 mm × 200 mm and a thickness of 2 mm, and subjected to autoclave treatment (temperature 80 ° C., atmospheric pressure 0.4 MPa, 30 minutes).
The pressure-sensitive adhesive sheet laminates 1, 2, 4, 5, 6, and 7 were irradiated with light using a high-pressure mercury lamp so that the integrated light amount at a wavelength of 405 nm was 3000 mJ / cm ^2, and an evaluation sample was prepared.

The evaluation sample was irradiated with ultraviolet rays for 24 hours using a xenon light resistance tester (Suntest CPS, manufactured by Atlas), and the adhesive sheet with no floating was found to have light resistance "○ (good)". , Those with floating or peeling were judged to have light resistance "x (poor)". The results are shown in Table 1.

A peel-treated polyethylene terephthalate film (manufactured by Mitsubishi Resin Co., Ltd., diafoil MRV, thickness 100 μm) used in Example 1, a PET film containing an ultraviolet absorber (thickness 100 μm) used in Example 4, and a silicone release agent. With respect to the release film coated with the above and the surface protective film used in Example 5, the light transmittance in the wavelength range of 380 to 450 nm was measured with a spectrophotometer (manufactured by Shimadzu Corporation; device name “UV2450”). The results are shown in Table 2.

Polyethylene terephthalate film (manufactured by Mitsubishi Resin Co., Ltd., Diafoil MRV, thickness 100 μm) that has been peeled off from the adhesive sheet laminate 1, the adhesive sheet laminate 4, and the adhesive sheet laminate 5, respectively, and the ultraviolet absorber used in Example 4. The PET film containing the mixture (thickness 100 μm) was allowed to stand with the release film coated with the silicone release agent and the surface protective film side facing up. Light from a fluorescent lamp (illuminance 1100 Lx) was irradiated from the film side for 7 days. The integrated light amount of the irradiated light at a wavelength of 405 nm was about 43 J / cm ² , and the integrated light amount at a wavelength of 365 nm was about 1 mJ / cm ² or less, which was unmeasurable.

For the pressure-sensitive adhesive sheet laminates 1 and 4 before and after the light irradiation treatment, the gel fraction of the pressure-sensitive adhesive material was determined by the following method. The results are shown in Table 2.

1) The pressure-sensitive adhesive composition is weighed (W1) and wrapped in a pre-weighted SUS mesh (W0).
2) Immerse the SUS mesh in 100 mL of ethyl acetate for 24 hours.
3) Take out the SUS mesh and dry it at 75 ° C. for 4 and a half hours.
4) Determine the weight (W2) after drying, and measure the gel fraction of the pressure-sensitive adhesive composition from the following formula.
Gel fraction (%) = 100 x (W2-W0) / W1

Regarding storage stability, “○ (good)” indicates that the change in gel fraction was less than 5 points before and after irradiation with fluorescent light, and “× (poor)” indicates that the gel fraction increased by 5 points or more after irradiation with light. It was judged. The results are shown in Table 2.

The adhesive sheet laminates of Examples 1 to 5 not only had excellent ultraviolet absorption performance, but also had excellent quality that achieved both uneven absorption at the time of bonding and reliability after bonding of members. ..
On the other hand, Comparative Example 1 used a photopolymerization initiator having an extinction coefficient of less than 10 mL / (g · cm) at a wavelength of 405 nm, that is, starting photopolymerization having an extinction coefficient of 10 mL / (g · cm) or more at a wavelength of 405 nm. Since no agent was used, the adhesive material did not cure even when irradiated with light, and the adhesive strength after secondary bonding and the reliability after bonding could not be obtained.
Comparative Example 2 did not contain the ultraviolet absorber (D), and the ultraviolet absorbing performance could not be obtained. For this reason, foaming of the adhesive sheet was observed in the light resistance test, and the bonding reliability was inferior.
Comparative Example 3 is a pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive composition is crosslinked by thermal cross-linking. Since it does not have a photocurable layer, it is inferior in the unevenness absorption at the time of bonding.

Further, in Example 4, a PET film containing an ultraviolet absorber is used as the release film. As a result, it was possible to suppress the progress of the photocuring reaction of the pressure-sensitive adhesive composition before it was bonded to the member, and it was possible to obtain a pressure-sensitive adhesive sheet laminate having excellent storage stability.

Further, in Example 5, a surface protective film having an ultraviolet absorbing layer is laminated on the surface of the release film. As a result, it was possible to suppress the progress of the photocuring reaction of the pressure-sensitive adhesive composition before it was bonded to the member, and it was possible to obtain a pressure-sensitive adhesive sheet laminate having excellent storage stability.

Claims (12)

Contains (meth) acrylic copolymer (A), cross-linking agent (B), photopolymerization initiator (C) having an absorption coefficient of 10 mL / (g · cm) or more at a wavelength of 405 nm, and an ultraviolet absorber (D). A single layer or two or more pressure-sensitive adhesive layers formed from the pressure-sensitive adhesive resin composition.
A transparent double-sided pressure-sensitive adhesive sheet containing at least a polyfunctional (meth) acrylate as the cross-linking agent (B) and the pressure-sensitive adhesive layer being photocurable. The transparent double-sided pressure-sensitive adhesive sheet according to claim 1, wherein the (meth) acrylic copolymer (A) is an acrylic copolymer composed of a graft copolymer having a macromonomer as a branch component. The transparent double-sided pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the ultraviolet absorber (D) has a structure selected from the group consisting of a benzotriazole structure, a triazine structure and a benzophenone structure. The transparent double-sided pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the ultraviolet absorber (D) is contained in a ratio of 25 to 400 parts by mass with respect to 100 parts by mass of the photopolymerization initiator (C). .. The (meth) acrylic copolymer (A) contains an acrylic copolymer composed of a graft copolymer having a macromonomer as a branch component, and the cross-linking agent (B) is a polyfunctional (meth) acrylic acid. Contains ester compounds,
Claims 1 to 1, wherein the photopolymerization initiator (C) contains a cleavage-type photopolymerization initiator, and the ultraviolet absorber (D) contains an ultraviolet absorber having a benzotriazole structure or a benzophenone structure. The transparent double-sided adhesive sheet according to any one of 4. Claim 1 has the property of exhibiting adhesiveness at room temperature (20 ° C.) and softening or fluidizing when heated to a temperature of 50 to 100 ° C. even when the pressure-sensitive adhesive resin composition is in an uncrosslinked state. The transparent double-sided adhesive sheet according to any one of ~ 5. A pressure-sensitive adhesive sheet laminate having a structure in which the pressure-sensitive adhesive sheet according to any one of claims 1 to 6 and a release film are laminated. The pressure-sensitive adhesive sheet laminate according to claim 7, wherein at least one release film has a light transmittance of 40% or less for light having a wavelength of 410 nm or less. The pressure-sensitive adhesive sheet laminate according to claim 7, further comprising a structure in which a surface protective film having a light transmittance of 40% or less for light having a wavelength of 410 nm or less is laminated on the surface of at least one release film. An image display device configuration laminate having a configuration in which two constituent members are laminated via the transparent double-sided adhesive sheet according to any one of claims 1 to 6. 10. The image display device component is a laminate composed of any one of the group consisting of a touch sensor, an image display panel, a surface protection panel, and a polarizing film, or a combination of two or more types. The laminate for configuring an image display device according to the description. An image display device configured by using the image display device configuration laminate according to claim 10 or 11.