Acrylic pressure-sensitive adhesive composition, pressure-sensitive adhesive layer and method for producing same, polarizing film with pressure-sensitive adhesive layer, and image display device

文档序号：1948191 发布日期：2021-12-10 浏览：11次中文

阅读说明：本技术 丙烯酸类粘合剂组合物、粘合剂层及其制造方法、带粘合剂层的偏振膜及图像显示装置 (Acrylic pressure-sensitive adhesive composition, pressure-sensitive adhesive layer and method for producing same, polarizing film with pressure-sensitive adhesive layer, and image display device ) 是由山本真也形见普史保井淳于 2016-06-15 设计创作，主要内容包括：本申请涉及丙烯酸类粘合剂组合物、粘合剂层及其制造方法、带粘合剂层的偏振膜及图像显示装置。一种紫外线固化型丙烯酸类粘合剂组合物,其用于形成位于图像显示装置中的保护玻璃或保护塑料与偏振膜之间的粘合剂层,其特征在于,所述粘合剂组合物包含：含有(甲基)丙烯酸烷基酯的单体成分和/或所述单体成分的部分聚合物、紫外线吸收剂、以及在波长400nm以上具有吸收带的光聚合引发剂(A),并且由所述粘合剂组合物形成的粘合剂层的波长380nm下的透射率为40％以下,并且波长400nm下的透射率为30％以上。(The present application relates to an acrylic pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer and a method for producing the same, a polarizing film with a pressure-sensitive adhesive layer, and an image display device. An ultraviolet-curable acrylic adhesive composition for forming an adhesive layer between a protective glass or a protective plastic and a polarizing film in an image display device, characterized in that the adhesive composition comprises: the adhesive composition comprises a monomer component containing an alkyl (meth) acrylate and/or a partial polymer of the monomer component, an ultraviolet absorber, and a photopolymerization initiator (A) having an absorption band at a wavelength of 400nm or more, and the adhesive layer formed from the adhesive composition has a transmittance of 40% or less at a wavelength of 380nm and a transmittance of 30% or more at a wavelength of 400 nm.)

1. An ultraviolet-curable acrylic adhesive composition for forming an adhesive layer between a protective glass or a protective plastic and a polarizing film in an image display device,

it is characterized in that the preparation method is characterized in that,

the adhesive composition comprises: a monomer component containing an alkyl (meth) acrylate and/or a partial polymer of the monomer component, an ultraviolet absorber, a photopolymerization initiator (A) having an absorption band at a wavelength of 400nm or more, and a photopolymerization initiator (B) having an absorption band at a wavelength of less than 400nm,

the alkyl (meth) acrylate is 40 wt% or more with respect to the total amount of monofunctional monomer components in the monomer components,

the amount of the photopolymerization initiator (A) added is less than the amount of the ultraviolet absorber added, and

the transmittance of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition at a wavelength of 380nm is 40% or less, and the transmittance of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition at a wavelength of 400nm is 30% or more.

2. The ultraviolet-curable acrylic adhesive composition according to claim 1,

the adhesive layer has a transmission b value of 3.0 or less.

3. The ultraviolet-curable acrylic adhesive composition according to claim 1,

the ultraviolet absorber is at least one ultraviolet absorber selected from the group consisting of triazine ultraviolet absorbers having 2 or less hydroxyl groups in one molecule and benzotriazole ultraviolet absorbers having 1 benzotriazole skeleton in one molecule.

4. An ultraviolet-curable acrylic adhesive layer which is an adhesive layer between a protective glass or a protective plastic and a polarizing film in an image display device, characterized in that,

the ultraviolet-curable acrylic pressure-sensitive adhesive layer is formed by irradiating the ultraviolet-curable acrylic pressure-sensitive adhesive composition according to any one of claims 1 to 3 with ultraviolet rays to photopolymerize monomer components in the ultraviolet-curable acrylic pressure-sensitive adhesive composition.

5. A polarizing film having an adhesive layer,

the polarizing film with an adhesive layer has a polarizing film and the ultraviolet ray-curable acrylic adhesive layer of claim 4 on at least one side of the polarizing film.

6. A method for producing an ultraviolet-curable acrylic pressure-sensitive adhesive layer, which comprises forming the pressure-sensitive adhesive layer from the ultraviolet-curable acrylic pressure-sensitive adhesive composition according to claim 1,

it is characterized in that the preparation method is characterized in that,

the manufacturing method comprises the following steps: irradiating a composition containing a monomer component containing an alkyl (meth) acrylate and the photopolymerization initiator (B) with ultraviolet rays to form a partial polymer of the monomer component;

a step of adding an ultraviolet absorber and a photopolymerization initiator (A) having an absorption band at a wavelength of 400nm or more to a partial polymer of the monomer component to prepare an ultraviolet-curable acrylic pressure-sensitive adhesive composition; and

and a step of applying the ultraviolet-curable acrylic pressure-sensitive adhesive composition to at least one surface of a substrate and irradiating the ultraviolet-curable acrylic pressure-sensitive adhesive composition with ultraviolet light.

7. An image display device having at least a protective glass or a protective plastic and a polarizing film,

it is characterized in that the preparation method is characterized in that,

the image display device has the ultraviolet ray-curable acrylic adhesive agent layer of claim 4 between the protective glass or plastic and a polarizing film.

Technical Field

The present invention relates to an ultraviolet-curable acrylic adhesive composition for forming an adhesive layer between a protective glass or a protective plastic and a polarizing film in an image display device. The present invention also relates to an ultraviolet-curable acrylic pressure-sensitive adhesive layer formed from the ultraviolet-curable acrylic pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer-attached polarizing film having the ultraviolet-curable acrylic pressure-sensitive adhesive layer, a method for producing the ultraviolet-curable acrylic pressure-sensitive adhesive layer, and an image display device. Examples of the image display device include a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), and electronic paper.

Background

In a liquid crystal display device, an organic EL display device, or the like, for example, in a liquid crystal display device, it is essential to dispose polarizing elements on both sides of a liquid crystal cell because of an image forming method, and a polarizing film is generally attached. In addition, in display panels such as liquid crystal panels and organic EL panels, various optical elements are used in addition to polarizing films in order to improve the display quality of displays.

Polarizing films used in these image display devices generally have a configuration in which a polarizer is sandwiched by two protective films, and triacetyl cellulose (TAC) is widely used as the protective film.

In recent years, with the trend toward weight reduction and film thinning of image display devices, thinning of each member used in the image display devices is required, and thinning of a protective film of a polarizing film is also required. When the thickness of the protective film is reduced, ultraviolet rays incident on the image display device cannot be sufficiently blocked, and there is a problem that deterioration of the polarizer due to ultraviolet rays is accelerated, and deterioration of various optical members including a liquid crystal panel, an organic EL element, and the like used in the image display device due to ultraviolet rays is also accelerated.

To eliminate such problems, for example, there are known: a transparent double-sided adhesive sheet for an image display device, which is provided between a surface protection panel and a viewing side of a liquid crystal module in the image display device, for integrating both members, wherein the double-sided adhesive sheet has at least one ultraviolet absorbing layer, has a light transmittance of 30% or less at a wavelength of 380nm, and has a visible light transmittance of 80% or more at a longer wavelength side than a wavelength of 430nm (for example, see patent document 1); an adhesive sheet having an adhesive layer containing an acrylic polymer and a triazine-based ultraviolet absorber (for example, see patent document 2). In addition, it is known that an adhesive optical film in which an adhesive layer is provided on one side or both sides of an optical film can impart ultraviolet absorption capability to the adhesive layer (for example, see patent document 3).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2012-211305

Patent document 2: japanese patent laid-open publication No. 2013-75978

Patent document 3: japanese patent No. 4208187

Disclosure of Invention

Problems to be solved by the invention

In the pressure-sensitive adhesive sheets of patent documents 1 and 2, the pressure-sensitive adhesive layer containing the ultraviolet absorber is thin, and therefore the ultraviolet absorbing function is insufficient. Further, since the adhesive layer is thin, when the uneven (height difference) absorbency is required, there may be a problem such as the generation of bubbles. In these patent documents, polymerization by ultraviolet irradiation is not performed when forming a pressure-sensitive adhesive layer containing an ultraviolet absorber, and it is needless to say that no study has been made on a photopolymerization initiator having an absorption band at a wavelength of 400nm or more.

In patent document 3, no specific study has been made at all on the formation of an adhesive layer having an ultraviolet absorbing function by a polymerization method using ultraviolet irradiation, and no sufficient study has been made on a photopolymerization initiator having an absorption band at a wavelength of 400nm or more.

In addition to patent documents 1 to 3, various transparent adhesives having an ultraviolet absorbing function are known, but most of the transparent adhesives having an ultraviolet absorbing function known so far are base polymers for producing adhesives by solution polymerization. It is difficult to manufacture a thick product of 150 μm or more by such a manufacturing method, and there is a limit in the thickness of the pressure-sensitive adhesive layer that can be manufactured. It is known that a thick pressure-sensitive adhesive layer can be formed by using a polymerization method using ultraviolet irradiation, but a method for forming a pressure-sensitive adhesive layer having an ultraviolet absorbing function by using a polymerization method using ultraviolet irradiation is not known in the related art.

Accordingly, an object of the present invention is to provide an ultraviolet-curable acrylic pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer having an ultraviolet absorbing function by a polymerization method using ultraviolet irradiation. Further, another object of the present invention is to provide an ultraviolet-curable acrylic pressure-sensitive adhesive layer formed from the ultraviolet-curable acrylic pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer-attached polarizing film having the ultraviolet-curable acrylic pressure-sensitive adhesive layer, a method for producing the ultraviolet-curable acrylic pressure-sensitive adhesive layer, and an image display device.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems and as a result, have found the following ultraviolet-curable acrylic pressure-sensitive adhesive composition, and have completed the present invention.

That is, the present invention relates to an ultraviolet-curable acrylic adhesive composition for forming an adhesive layer between a protective glass or a protective plastic and a polarizing film in an image display device,

it is characterized in that the preparation method is characterized in that,

the adhesive composition comprises: a monomer component containing alkyl (meth) acrylate and/or a partial polymer of the monomer component, an ultraviolet absorber, and a photopolymerization initiator (A) having an absorption band at a wavelength of 400nm or more, and

Preferably, the adhesive layer has a transmission b value of 3.0 or less.

Preferably, the ultraviolet absorber is at least one ultraviolet absorber selected from the group consisting of triazine ultraviolet absorbers having 2 or less hydroxyl groups in one molecule and benzotriazole ultraviolet absorbers having 1 benzotriazole skeleton in one molecule.

The amount of the photopolymerization initiator (a) added is preferably less than the amount of the ultraviolet absorber added.

It is preferable that the ultraviolet-curable acrylic adhesive composition of the present invention further contains a photopolymerization initiator (B) having an absorption band at a wavelength of less than 400 nm.

The present invention relates to an ultraviolet-curable acrylic adhesive layer which is an adhesive layer between a protective glass or a protective plastic and a polarizing film in an image display device,

it is characterized in that the preparation method is characterized in that,

the ultraviolet-curable acrylic pressure-sensitive adhesive layer is formed by irradiating the ultraviolet-curable acrylic pressure-sensitive adhesive composition with ultraviolet rays to photopolymerize monomer components in the ultraviolet-curable acrylic pressure-sensitive adhesive composition.

The present invention relates to a polarizing film with an adhesive layer, characterized in that the polarizing film with an adhesive layer has a polarizing film and the ultraviolet-curable acrylic adhesive layer is provided on at least one surface of the polarizing film.

The present invention also relates to a method for producing an ultraviolet-curable acrylic pressure-sensitive adhesive layer, which is a method for producing a pressure-sensitive adhesive layer formed from an ultraviolet-curable acrylic pressure-sensitive adhesive composition containing the photopolymerization initiator (B),

it is characterized in that the preparation method is characterized in that,

Furthermore, the invention relates to an image display device having at least a protective glass or a protective plastic and a polarizing film,

it is characterized in that the preparation method is characterized in that,

the image display device has the ultraviolet-curing acrylic adhesive layer between the protective glass or protective plastic and a polarizing film.

Effects of the invention

The ultraviolet-curable acrylic pressure-sensitive adhesive composition of the present invention can form a pressure-sensitive adhesive layer having an ultraviolet absorbing function by a polymerization method using ultraviolet irradiation, and therefore can form a pressure-sensitive adhesive layer having a thickness of 150 μm or more and a pressure-sensitive adhesive layer having a wide thickness range. The pressure-sensitive adhesive layer of the present invention has an excellent ultraviolet absorption function, and therefore, when the pressure-sensitive adhesive layer is used in an image display device, deterioration of optical members including a liquid crystal panel, an organic EL element, a polarizer, and the like can be suppressed.

Drawings

Fig. 1 is a cross-sectional view schematically showing one embodiment of an image display device of the present invention.

Fig. 2 is a cross-sectional view schematically showing one embodiment of the image display device of the present invention.

Fig. 3 is a cross-sectional view schematically showing one embodiment of the image display device of the present invention.

Detailed Description

1. Ultraviolet-curable acrylic adhesive composition

The ultraviolet-curable acrylic adhesive composition of the present invention is used for forming an adhesive layer between a protective glass or a protective plastic and a polarizing film in an image display device,

it is characterized in that the preparation method is characterized in that,

An embodiment of an image display device including the adhesive layer of the present invention is described in detail with reference to the drawings. However, the invention is not limited to the embodiments of the figures.

As an example of the configuration of the image display device, for example, as shown in fig. 1 to 3, for example, as shown in

Protective glass or protective plastic 1/adhesive layer 2 a/polarizing film 5/liquid crystal display device (LCD) or organic EL display device (OLED) 6;

protective glass or protective plastic 1/adhesive layer 2 b/sensor layer 7/adhesive layer 2 a/polarizing film 5/liquid crystal display device (LCD) or organic EL display device (OLED) 6;

protective glass or protective plastic 1/adhesive layer 2 b/sensor layer 7/adhesive layer 2 c/sensor layer 7/adhesive layer 2 a/polarizing film 5/liquid crystal display device (LCD) or organic EL display device (OLED) 6; in that way,

and an image display device obtained by sequentially laminating the layers. In addition to these layers, a retardation film or the like may be added as appropriate, and specifically, the polarizing film 5 and the liquid crystal display device (LCD) or the organic EL display device (OLED)6 may be laminated via an adhesive layer. In addition, in the lamination of each layer, a pressure-sensitive adhesive layer and/or an adhesive layer may be appropriately used. The polarizing film 5 in fig. 1 to 3 has a structure in which the polarizer 4 is sandwiched between two protective films 3a and 3b, but may be a single-sided protective polarizing film in which one side of the polarizer 4 is protected by a protective film.

The pressure-sensitive adhesive layer containing the ultraviolet-curable acrylic pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive layer between the protective glass or protective plastic 1 in the image display device and the polarizing film 5 present at a portion closer to the viewing side than the liquid crystal display device (LCD) or organic EL display device (OLED)6, and may be located at any position of the pressure-sensitive adhesive layers 2a to 2c in fig. 1 to 3, and from the viewpoint of ultraviolet absorption ability, the pressure-sensitive adhesive layer of the present invention is more preferably used in the pressure-sensitive adhesive layer (2 a in the figure) in contact with the polarizing film 5. By disposing the pressure-sensitive adhesive layer containing the ultraviolet-curable acrylic pressure-sensitive adhesive composition of the present invention at the above position, the polarizing film and the like in the image display device can be protected from the ultraviolet rays incident from the viewing side in the image display device, and therefore, it is preferable.

The ultraviolet-curable acrylic adhesive composition of the present invention comprises: a monomer component containing an alkyl (meth) acrylate and/or a partial polymer of the monomer component, an ultraviolet absorber, and a photopolymerization initiator (A) having an absorption band at a wavelength of 400nm or more.

Examples of the alkyl (meth) acrylate include alkyl (meth) acrylates having a linear or branched alkyl group having 1 to 24 carbon atoms at the ester end. The alkyl (meth) acrylate may be used singly or in combination of two or more. The alkyl (meth) acrylate means an alkyl acrylate and/or an alkyl methacrylate, and the same meaning is applied to (meth) in the present invention.

Examples of the alkyl (meth) acrylate include alkyl (meth) acrylates having an alkyl group containing a branch having 4 to 9 carbon atoms at the end of an ester group. The alkyl (meth) acrylate is preferable in terms of easily obtaining a balance of adhesive properties. Specifically, there may be mentioned: n-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, isohexyl (meth) acrylate, isoheptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, and the like, and these may be used singly or in combination of two or more.

In the present invention, the alkyl (meth) acrylate having an alkyl group having 1 to 24 carbon atoms at the ester end is preferably 40% by weight or more, more preferably 50% by weight or more, and still more preferably 60% by weight or more, based on the total amount of monofunctional monomer components forming the (meth) acrylic polymer.

A comonomer other than the alkyl (meth) acrylate may be contained as a monofunctional monomer component in the monomer components forming the (meth) acrylic polymer. The comonomer may be used as the rest of the monomer components other than the alkyl (meth) acrylate.

As the comonomer, for example, a cyclic nitrogen-containing monomer may be contained. The cyclic nitrogen-containing monomer is not particularly limited, and a monomer having a cyclic nitrogen structure and having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group can be used. The cyclic nitrogen structure preferably has a nitrogen atom within the cyclic structure. Examples of the cyclic nitrogen-containing monomer include: lactam-type vinyl monomers such as N-vinylpyrrolidone, N-vinyl-epsilon-caprolactam and methyl vinyl pyrrolidone; vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, ethylenePyrrole, vinylimidazole, vinylVinyl monomers having a nitrogen-containing heterocycle such as oxazole and vinyl morpholine. In addition, there may be mentioned: (meth) acrylic monomers containing a heterocyclic ring such as a morpholine ring, a piperidine ring, a pyrrolidine ring, or a piperazine ring. Specifically, there may be mentioned: n-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine and the like. Among the cyclic nitrogen-containing monomers, lactam-based vinyl monomers are preferable.

In the present invention, the cyclic nitrogen-containing monomer is preferably 0.5 to 50% by weight, more preferably 0.5 to 40% by weight, and still more preferably 0.5 to 30% by weight, based on the total amount of the monofunctional monomer components forming the (meth) acrylic polymer.

The monomer component used in the present invention may contain a hydroxyl group-containing monomer as a monofunctional monomer component. As the hydroxyl group-containing monomer, a monomer having a hydroxyl group and containing a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group can be used without particular limitation. Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, and 12-hydroxylauryl (meth) acrylate; hydroxyalkyl (meth) acrylates such as (4-hydroxymethylcyclohexyl) methyl (meth) acrylate. Further, hydroxyethyl (meth) acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether and the like are exemplified. These hydroxyl group-containing monomers may be used alone or in combination. Among them, hydroxyalkyl (meth) acrylates are preferable.

In the present invention, the hydroxyl group-containing monomer is preferably 1% by weight or more, more preferably 2% by weight or more, and further preferably 3% by weight or more, based on the total amount of monofunctional monomer components forming the (meth) acrylic polymer, from the viewpoint of improving the adhesive strength and cohesive strength. On the other hand, when the hydroxyl group-containing monomer is too much, the pressure-sensitive adhesive layer may be hardened to lower the adhesive strength, and the viscosity of the pressure-sensitive adhesive may be too high or gelation may occur, so that the hydroxyl group-containing monomer is preferably 30% by weight or less, more preferably 27% by weight or less, and still more preferably 25% by weight or less, based on the total amount of the monofunctional monomer components forming the (meth) acrylic polymer.

In addition, other functional group-containing monomers may be contained as monofunctional monomers in the monomer components forming the (meth) acrylic polymer, and examples thereof include carboxyl group-containing monomers and cyclic ether group-containing monomers.

As the carboxyl group-containing monomer, a monomer having a carboxyl group and containing a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group can be used without particular limitation. Examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid, and these carboxyl group-containing monomers may be used alone or in combination. For itaconic acid and maleic acid, anhydrides thereof may be used. Among them, acrylic acid and methacrylic acid are preferable, and acrylic acid is particularly preferable. The carboxyl group-containing monomer may be optionally used in the monomer components used for producing the (meth) acrylic polymer, and the carboxyl group-containing monomer may not be used.

As the monomer having a cyclic ether group, a monomer containing a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a cyclic ether group such as an epoxy group or an oxetanyl group can be used without particular limitation. Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, 3, 4-epoxycyclohexylmethyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate glycidyl ether. Examples of the oxetanyl-containing monomer include 3-oxetanylmethyl (meth) acrylate, 3-methyl-3-oxetanylmethyl (meth) acrylate, 3-ethyl-3-oxetanylmethyl (meth) acrylate, 3-butyl-3-oxetanylmethyl (meth) acrylate, and 3-hexyl-3-oxetanylmethyl (meth) acrylate. These monomers having a cyclic ether group may be used alone or in combination.

In the present invention, the carboxyl group-containing monomer and the monomer having a cyclic ether group are preferably 30% by weight or less, more preferably 27% by weight or less, and still more preferably 25% by weight or less, based on the total amount of monofunctional monomer components forming the (meth) acrylic polymer.

Among the monomer components forming the (meth) acrylic polymer, the comonomer may be, for example, CH₂＝C(R¹)COOR²(above-mentioned R¹Represents hydrogen or methyl, R²A substituted alkyl group having 1 to 3 carbon atoms or a cyclic cycloalkyl group).

Herein as R²The substituent of the substituted alkyl group having 1 to 3 carbon atoms is preferably an aryl group having 3 to 8 carbon atoms or an aryloxy group having 3 to 8 carbon atoms. As the aryl group, there is no limitation, but a phenyl group is preferable.

As such composed of CH₂＝C(R¹)COOR²Examples of the monomer include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, 3, 5-trimethylcyclohexyl (meth) acrylate, isobornyl (meth) acrylate, and the like. These monomers may be used alone or in combination.

In the present invention, the above-mentioned group consisting of CH with respect to the total amount of monofunctional monomer components forming the (meth) acrylic polymer₂＝C(R¹)COOR²The (meth) acrylate may be used in an amount of 50 wt% or less, preferably 45 wt% or less, more preferably 40 wt% or less, and still more preferably 35 wt% or less.

As further comonomers, it is also possible to use vinyl acetate, vinyl propionate, styrene, α -methylstyrene; glycol acrylate monomers such as polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, methoxyethylene glycol (meth) acrylate, and methoxypolypropylene glycol (meth) acrylate; acrylic ester monomers such as tetrahydrofurfuryl (meth) acrylate, fluoro (meth) acrylate, silicone (meth) acrylate, and 2-methoxyethyl acrylate; amide group-containing monomers, amino group-containing monomers, imide group-containing monomers, N-acryloyl morpholine, vinyl ether monomers, and the like. As the comonomer, a monomer having a cyclic structure such as terpene (meth) acrylate or tetrahydrodicyclopentadiene (meth) acrylate can be used.

Further, silane monomers containing a silicon atom are exemplified. Examples of the silane monomer include: 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloxydecyltrimethoxysilane, 10-acryloxydecyltrimethoxysilane, 10-methacryloxydecyltriethoxysilane, 10-acryloxydecyltriethoxysilane, and the like.

The monomer component forming the (meth) acrylic polymer may contain a polyfunctional monomer as necessary for adjusting the cohesive force of the adhesive, in addition to the monofunctional monomer exemplified above.

The polyfunctional monomer is a monomer having at least two polymerizable functional groups having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group, and examples thereof include: ester compounds of a polyhydric alcohol and (meth) acrylic acid such as (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1, 2-ethylene glycol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, 1, 12-dodecanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and tetramethylolmethane tri (meth) acrylate; allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate, and the like. Among them, trimethylolpropane tri (meth) acrylate, hexanediol di (meth) acrylate, dipentaerythritol hexa (meth) acrylate can be preferably used. The polyfunctional monomer may be used singly or in combination of two or more.

The amount of the polyfunctional monomer used varies depending on the molecular weight, the number of functional groups, and the like, and is preferably 3 parts by weight or less, more preferably 2 parts by weight or less, and still more preferably 1 part by weight or less, based on 100 parts by weight of the total amount of the monofunctional monomers. The lower limit is not particularly limited, but is preferably 0 part by weight or more, and more preferably 0.001 part by weight or more. When the amount of the polyfunctional monomer used is within the above range, the adhesive strength can be improved.

In the present invention, the monomer component may be a partial polymer. The "partial polymer" as used herein means a polymer obtained by partially polymerizing a monomer component. The polymerization rate of the partial polymer of the monomer component is as follows.

The ultraviolet-curable acrylic adhesive composition of the present invention contains an ultraviolet absorber.

The ultraviolet absorber is not particularly limited, and examples thereof include: triazine ultraviolet absorbers, benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, hydroxybenzophenone ultraviolet absorbers, salicylate ultraviolet absorbers, cyanoacrylate ultraviolet absorbers, and the like, and these ultraviolet absorbers may be used singly or in combination of two or more. Among these, the triazine-based ultraviolet absorber and the benzotriazole-based ultraviolet absorber are preferable, and at least one ultraviolet absorber selected from the group consisting of triazine-based ultraviolet absorbers having two or less hydroxyl groups in one molecule and benzotriazole-based ultraviolet absorbers having one benzotriazole skeleton in one molecule is preferable because of its good solubility in monomers used for forming the ultraviolet-curable acrylic adhesive composition and its high ultraviolet absorption ability at a wavelength around 380 nm.

As the triazine-based ultraviolet absorber having 2 or less hydroxyl groups in one molecule, specifically, there can be used: 2, 4-bis [ {4- (4-ethylhexyloxy) -4-hydroxy } phenyl]-6- (4-methoxyphenyl) -1,3, 5-triazine (manufactured by Tinosorb S, BASF); 2, 4-bis [ 2-hydroxy-4-butoxyphenyl group]-6- (2, 4-dibutoxyphenyl) -1,3, 5-triazine (TINUVIN 460, manufactured by BASF); 2- (4, 6-bis (2, 4-dimethylphenyl) -1,3, 5-triazin-2-yl) -5-hydroxyphenyl and [ (C)₁₀-C₁₆(mainly C)₁₂-C₁₃) Alkyloxy) methyl]Reaction products of ethylene oxide (TINUVIN400, manufactured by BASF); 2- [4, 6-bis (2, 4-dimethylphenyl) -1,3, 5-triazin-2-yl]-5- [3- (dodecyloxy) -2-hydroxypropoxy group]Phenol), a reaction product of 2- (2, 4-dihydroxyphenyl) -4, 6-bis (2, 4-dimethylphenyl) -1,3, 5-triazine and 2-ethylhexyl glycidate (TINUVIN405, manufactured by BASF); 2- (4, 6-Diphenyl-1, 3, 5-triazin-2-yl) -5- [ (hexyl) oxy]Phenol (TINUVIN1577, manufactured by BASF); 2- (4, 6-Diphenyl-1, 3, 5-triazin-2-yl) -5- [2- (2-ethylhexanoyloxy) ethoxy]Phenol (ADK STAB LA46, made by Ediko (ADEKA) Co., Ltd.); 2- (2-hydroxy-4- [ 1-octyloxycarbonylethoxy)]Phenyl) -4, 6-bis (4-phenylphenyl) -1,3, 5-triazine (TINUVIN479, manufactured by BASF).

As the benzotriazole-based ultraviolet absorber having one benzotriazole skeleton in one molecule, there can be used: 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3, 3-tetramethylbutyl) phenol (TINUVIN928, manufactured by BASF), an ester compound of 2- (2-hydroxy-5-tert-butylphenyl) -2H-benzotriazole (TINUVIN PS, manufactured by BASF), phenylpropionic acid and 3- (2H-benzotriazol-2-yl) -5- (1, 1-dimethylethyl) -4-hydroxy (C7-9 side chain and linear alkyl) (NUTIVIN 384-2, manufactured by BASF); 2- (2H-benzotriazol-2-yl) -4, 6-bis (1-methyl-1-phenylethyl) phenol (TINUVIN900, manufactured by BASF); 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3, 3-tetramethylbutyl) phenol (TINUVIN928, manufactured by BASF); a reaction product of methyl 3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate/polyethylene glycol 300 (TINUVIN1130 manufactured by BASF); 2- (2H-benzotriazol-2-yl) P-cresol (TINUVIN P, manufactured by BASF); 2- (2H-benzotriazol-2-yl) -4, 6-bis (1-methyl-1-phenylethyl) phenol (TINUVIN234, manufactured by BASF); 2- [ 5-chloro (2H) -benzotriazol-2-yl ] -4-methyl-6-tert-butylphenol (TINUVIN326, manufactured by BASF); 2- (2H-benzotriazol-2-yl) -4, 6-di-tert-amylphenol (TINUVIN328, manufactured by BASF); 2- (2H-benzotriazol-2-yl) -4- (1,1,3, 3-tetramethylbutyl) phenol (TINUVIN329, manufactured by BASF); a reaction product of methyl 3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate with polyethylene glycol 300 (TINUVIN213, manufactured by BASF); 2- (2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol (TINUVIN571, manufactured by BASF); 2- [ 2-hydroxy-3- (3,4,5, 6-tetrahydrophthalimidomethyl) -5-methylphenyl ] benzotriazole (Sumisorb250, manufactured by Sumitomo chemical Co., Ltd.), and the like.

Examples of the benzophenone-based ultraviolet absorber (benzophenone-based compound) and the hydroxybenzophenone-based ultraviolet absorber (hydroxybenzophenone-based compound) include: 2, 4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydrous and trihydrate salts), 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2 ', 4,4 ' -tetrahydroxybenzophenone, 2 ' -dihydroxy-4, 4-dimethoxybenzophenone, and the like.

Examples of the salicylate ultraviolet absorbers (salicylate-based compounds) include: phenyl 2-acryloyloxy benzoate, phenyl 2-acryloyloxy-3-methylbenzoate, phenyl 2-acryloyloxy-4-methylbenzoate, phenyl 2-acryloyloxy-5-methylbenzoate, phenyl 2-acryloyloxy-3-methoxybenzoate, phenyl 2-hydroxybenzoate, phenyl 2-hydroxy-3-methylbenzoate, phenyl 2-hydroxy-4-methylbenzoate, phenyl 2-hydroxy-5-methylbenzoate, phenyl 2-hydroxy-3-methoxybenzoate, 2, 4-di-tert-butylphenyl 3, 5-di-tert-butyl-4-hydroxybenzoate (TIVIN NU120, manufactured by BASF), and the like.

Examples of the cyanoacrylate-based ultraviolet absorber (cyanoacrylate-based compound) include: alkyl 2-cyanoacrylate, cycloalkyl 2-cyanoacrylate, alkoxyalkyl 2-cyanoacrylate, alkenyl 2-cyanoacrylate, alkynyl 2-cyanoacrylate, and the like.

The ultraviolet absorber may be used alone or in combination of two or more, and the total content is preferably about 0.1 to about 5 parts by weight, more preferably about 0.5 to about 3 parts by weight, based on 100 parts by weight of the monofunctional monomer component forming the (meth) acrylic polymer. When the amount of the ultraviolet absorber added is within the above range, the ultraviolet absorbing function of the pressure-sensitive adhesive layer can be sufficiently exhibited and ultraviolet polymerization is not inhibited, which is preferable.

The ultraviolet-curable acrylic pressure-sensitive adhesive composition of the present invention contains a photopolymerization initiator (a) having an absorption band at a wavelength of 400nm or more. The photopolymerization initiator (A) having an absorption band at a wavelength of 400nm or more may have an absorption band at a wavelength of 400nm or more, or may have an absorption band at a wavelength of less than 400 nm. When ultraviolet polymerization is performed in the case where an ultraviolet absorber is contained in the adhesive composition, ultraviolet rays are absorbed by the ultraviolet absorber and polymerization cannot be sufficiently performed. However, the adhesive composition of the present invention has the photopolymerization initiator (a) having an absorption band at a wavelength of 400nm or more, and thus can sufficiently perform polymerization despite containing an ultraviolet absorber.

Examples of the photopolymerization initiator (a) having an absorption band at a wavelength of 400nm or more include: bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide (Irgacure819, manufactured by BASF), 2,4, 6-trimethylbenzoyl diphenylphosphine oxide (LUCIRIN TPO, manufactured by BASF), and the like.

The photopolymerization initiator (A) having an absorption band at a wavelength of 400nm or more may be used alone or in combination of two or more.

The amount of the photopolymerization initiator (a) having an absorption band at a wavelength of 400nm or more is not particularly limited, but is preferably less than the amount of the ultraviolet absorber, and is preferably from about 0.005 to about 1 part by weight, more preferably from about 0.02 to about 0.5 part by weight, based on 100 parts by weight of the monofunctional monomer component forming the (meth) acrylic polymer. When the amount of the photopolymerization initiator (a) is within the above range, the ultraviolet polymerization can be sufficiently performed, and therefore, the amount is preferable.

The ultraviolet-curable acrylic pressure-sensitive adhesive composition of the present invention may contain a photopolymerization initiator (B) having an absorption band at a wavelength of less than 400 nm. The photopolymerization initiator (B) preferably has no absorption band at a wavelength of 400nm or more. The photopolymerization initiator (B) is not particularly limited as long as it generates radicals to initiate photopolymerization by ultraviolet light and has an absorption band at a wavelength of less than 400nm, and any of the photopolymerization initiators generally used can be appropriately used. For example, it is possible to use: benzoin ether type photopolymerization initiator, acetophenone type photopolymerization initiator, α -ketol type photopolymerization initiator, photoactive oxime type photopolymerization initiator, benzoin type photopolymerization initiator, benzil type photopolymerization initiator, benzophenone type photopolymerization initiator, ketal type photopolymerization initiator, thioxanthone type photopolymerization initiator, acylphosphine oxide type photopolymerization initiator, and the like.

Specifically, examples of the benzoin ether-based photopolymerization initiator include: benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2-dimethoxy-1, 2-diphenylethane-1-one, anisoin methyl ether, and the like.

Examples of the acetophenone-based photopolymerization initiator include: 2, 2-diethoxyacetophenone, 2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenylketone, 4-phenoxydichloroacetophenone, 4-tert-butyldichloroacetophenone and the like.

Examples of the α -ketol photopolymerization initiator include: 2-methyl-2-hydroxypropiophenone, 1- [4- (2-hydroxyethyl) phenyl ] -2-hydroxy-2-methylpropan-1-one, and the like.

Examples of the photoactive oxime photopolymerization initiator include: 1-phenyl-1, 2-propanedione-2- (O-ethoxycarbonyl) oxime, and the like.

Examples of the benzoin photopolymerization initiator include benzoin and the like.

Examples of the benzil photopolymerization initiator include benzil and the like.

Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3' -dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α -hydroxycyclohexylphenylketone.

The ketal-type photopolymerization initiator includes benzildimethylketal and the like.

Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2, 4-dimethylthioxanthone, isopropylthioxanthone, 2, 4-dichlorothioxanthone, 2, 4-diethylthioxanthone, 2, 4-diisopropylthioxanthone, and dodecylthioxanthone.

Examples of the acylphosphine oxide photopolymerization initiator include 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide, and the like.

The photopolymerization initiator (B) having an absorption band at a wavelength of less than 400nm may be used singly or in combination of two or more. The photopolymerization initiator (B) having an absorption band at a wavelength of less than 400nm may be added within a range not impairing the effects of the present invention, and the amount added is preferably from about 0.005 to about 0.5 parts by weight, more preferably from about 0.02 to about 0.1 parts by weight, based on 100 parts by weight of the monofunctional monomer component forming the (meth) acrylic polymer.

In the present invention, it is preferable that: the photopolymerization initiator (B) having an absorption band at a wavelength of less than 400nm is added to the monomer component, and a partial polymer (prepolymer composition) of the monomer component is obtained by polymerizing a part thereof by irradiation with ultraviolet rays, and the photopolymerization initiator (A) having an absorption band at a wavelength of 400nm or more and an ultraviolet absorber are added to the prepolymer composition to carry out ultraviolet polymerization. When the photopolymerization initiator (a) having an absorption band at a wavelength of 400nm or more is added to a partial polymer (prepolymer composition) of a monomer component obtained by partial polymerization by ultraviolet irradiation, it is preferable to add the photopolymerization initiator after dissolving the photopolymerization initiator in a monomer.

The ultraviolet-curable acrylic pressure-sensitive adhesive composition of the present invention may contain a silane coupling agent. The amount of the silane coupling agent blended is preferably 1 part by weight or less, more preferably 0.01 to 1 part by weight, and still more preferably 0.02 to 0.6 part by weight, based on 100 parts by weight of the monofunctional monomer component forming the (meth) acrylic polymer.

Examples of the silane coupling agent include: epoxy-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane and 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane; amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1, 3-dimethylbutylidene) propylamine, and N-phenyl-gamma-aminopropyltrimethoxysilane; (meth) acryloyl group-containing silane coupling agents such as 3-acryloyloxypropyltrimethoxysilane and 3-methacryloyloxypropyltriethoxysilane; and isocyanate group-containing silane coupling agents such as 3-isocyanatopropyltriethoxysilane.

The ultraviolet-curable acrylic pressure-sensitive adhesive composition of the present invention may contain a crosslinking agent. The crosslinking agent includes an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, a polysiloxane-based crosslinking agent, a silicone-based crosslinking agent, and a silicone-based crosslinking agent,Crosslinking agents such as oxazoline crosslinking agents, aziridine crosslinking agents, silane crosslinking agents, alkyl etherified melamine crosslinking agents, metal chelate crosslinking agents, and peroxides. The crosslinking agent may be used singly or in combination of two or more. Among them, isocyanate-based crosslinking agents are preferably used.

The crosslinking agent may be used singly or in combination of two or more, and the total content is preferably 5 parts by weight or less, more preferably 0.01 to 5 parts by weight, further preferably 0.01 to 4 parts by weight, and particularly preferably 0.02 to 3 parts by weight, based on 100 parts by weight of the monofunctional monomer component forming the (meth) acrylic polymer.

The isocyanate-based crosslinking agent is a compound having two or more isocyanate groups (including an isocyanate-regenerating functional group in which an isocyanate group is temporarily protected by a blocking agent, polymerization, or the like) in one molecule. Examples of the isocyanate-based crosslinking agent include aromatic isocyanates such as toluene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

More specifically, examples thereof include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate; aromatic diisocyanates such as 2, 4-tolylene diisocyanate, 4' -diphenylmethane diisocyanate, xylylene diisocyanate, and polymethylenepolyphenyl isocyanate; trimethylolpropane/tolylene diisocyanate trimer adduct (trade name: CORONATE L, manufactured by Nippon polyurethane industries, Ltd.), isocyanate adduct such as trimethylolpropane/hexamethylene diisocyanate trimer adduct (trade name: CORONATE HL, manufactured by Nippon polyurethane industries, Ltd.), isocyanurate form of hexamethylene diisocyanate (trade name: CORONATE, manufactured by Nippon polyurethane industries, Ltd.), trimethylolpropane adduct of xylylene diisocyanate (trade name: D110N, manufactured by Mitsui chemical Co., Ltd.), trimethylolpropane adduct of hexamethylene diisocyanate (trade name: D160N, manufactured by Mitsui chemical Co., Ltd.); polyether polyisocyanates, polyester polyisocyanates, adducts thereof with various polyols, polyisocyanates obtained by polyfunctionalization such as isocyanurate bond, biuret bond, allophanate bond, and the like.

The ultraviolet-curable acrylic pressure-sensitive adhesive composition of the present invention may contain, in addition to the above components, appropriate additives depending on the application. For example, there may be mentioned: tackifiers (e.g., substances which are solid, semisolid, or liquid at ordinary temperatures including rosin derivative resins, polyterpene resins, petroleum resins, oil-soluble phenol resins, and the like); hollow glass microspheres and the like as fillers; a plasticizer; an anti-aging agent; antioxidants, and the like.

In the present invention, the ultraviolet-curable acrylic pressure-sensitive adhesive composition is preferably adjusted to a viscosity suitable for an operation such as coating on a substrate. The viscosity of the ultraviolet-curable acrylic pressure-sensitive adhesive composition is adjusted by, for example, adding various polymers such as thickening additives, polyfunctional monomers, and the like, or partially polymerizing monomer components in the ultraviolet-curable acrylic pressure-sensitive adhesive composition. The partial polymerization may be performed before or after addition of various polymers such as thickening additives, polyfunctional monomers, and the like. The viscosity of the ultraviolet-curable acrylic pressure-sensitive adhesive composition varies depending on the amount of the additive or the like, and therefore the polymerization rate at the time of partial polymerization of the monomer component in the ultraviolet-curable acrylic pressure-sensitive adhesive composition cannot be uniquely determined, and is preferably about 20% or less, more preferably about 3% to about 20%, and further preferably about 5% to about 15%, on the basis of the total weight. If the viscosity is more than 20%, the viscosity becomes too high, and thus it is difficult to apply the coating to a substrate.

The value b of the transmittance of the pressure-sensitive adhesive layer formed from the ultraviolet-curable acrylic pressure-sensitive adhesive composition of the present invention is not particularly limited, and is preferably 3.0 or less, more preferably 1.5 or less, and still more preferably 0.5 or less. The b value is a b value (chroma) in a color system according to JIS Z8729, and can be measured, for example, using a spectrophotometer (product name: U4100, manufactured by hitachi seiko co).

The transmittance of the pressure-sensitive adhesive layer formed from the ultraviolet-curable acrylic pressure-sensitive adhesive composition of the present invention at a wavelength of 380nm is 40% or less, preferably 20% or less, and more preferably 8% or less. When the transmittance at a wavelength of 380nm is within the above range, incident ultraviolet rays can be sufficiently blocked, and thus deterioration of optical members including a liquid crystal panel, an organic EL element, a polarizer, and the like can be suppressed.

The transmittance of the pressure-sensitive adhesive layer formed from the ultraviolet-curable acrylic pressure-sensitive adhesive composition of the present invention at a wavelength of 400nm is 30% or more, preferably 50% or more, and more preferably 70% or more. When the transmittance at a wavelength of 400nm is within the above range, incident visible light can be sufficiently transmitted, and sufficient visibility can be ensured in the image display device, which is preferable.

2. Ultraviolet-curable acrylic pressure-sensitive adhesive layer

The ultraviolet-curable acrylic adhesive layer of the present invention is characterized in that the adhesive layer is located between a protective glass or a protective plastic and a polarizing film in an image display device, and

the pressure-sensitive adhesive layer is formed by irradiating the ultraviolet-curable acrylic pressure-sensitive adhesive composition with ultraviolet rays to photopolymerize monomer components in the ultraviolet-curable acrylic pressure-sensitive adhesive composition.

For the ultraviolet-curable acrylic adhesive composition, the above-mentioned composition can be used.

The illuminance of ultraviolet light with which the above-mentioned ultraviolet-curable acrylic pressure-sensitive adhesive composition is irradiated is preferably 5mW/cm²The above. The illuminance of the ultraviolet ray is less than 5mW/cm²In this case, the polymerization reaction time is prolonged, and the productivity is sometimes poor. The illuminance of the ultraviolet light is preferably 200mW/cm²The following. The illumination intensity of the ultraviolet ray is more than 200mW/cm²In this case, the photopolymerization initiator is rapidly consumed, and thus the polymer may have a low molecular weight, and particularly the holding power at high temperature may be lowered. Further, the cumulative quantity of ultraviolet light is preferably 100mJ/cm²～5000mJ/cm²。

The ultraviolet lamp used in the present invention is not particularly limited, and an LED lamp is preferable. The LED lamp is a lamp that emits heat less than other ultraviolet lamps, and thus can suppress the temperature in polymerization of the adhesive layer. Therefore, the polymer can be prevented from having a low molecular weight, the cohesive force of the adhesive layer can be prevented from decreasing, and the holding force at high temperature can be improved when the adhesive sheet is produced. Further, a plurality of ultraviolet lamps may be combined. Alternatively, the ultraviolet light may be intermittently irradiated, and a light period in which the ultraviolet light is irradiated and a dark period in which the ultraviolet light is not irradiated may be provided.

In the present invention, the final polymerization rate of the monomer component in the ultraviolet-curable acrylic pressure-sensitive adhesive composition is preferably 90% or more, more preferably 95% or more, and still more preferably 98% or more.

In the present invention, the peak wavelength of ultraviolet light with which the ultraviolet-curable acrylic pressure-sensitive adhesive composition is irradiated is preferably in the range of 200nm to 500nm, more preferably in the range of 300nm to 450 nm. When the peak wavelength of ultraviolet light is more than 500nm, the photopolymerization initiator may not be decomposed and the polymerization reaction may not be initiated. When the peak wavelength of ultraviolet light is less than 200nm, the polymer chains may be cut, and the adhesive properties may be degraded.

From the viewpoint of ensuring the ultraviolet absorbing function, the thickness of the pressure-sensitive adhesive layer of the present invention is preferably 50 μm or more, more preferably 100 μm or more, and still more preferably 150 μm or more. The upper limit of the thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably 10mm or less. When the thickness of the pressure-sensitive adhesive layer is more than 10mm, it is not preferable because it is difficult to transmit ultraviolet rays, and it takes time to polymerize the monomer component, resulting in poor productivity.

The gel fraction of the pressure-sensitive adhesive layer of the present invention is not particularly limited, but is preferably 50% or more, more preferably 75% or more, and still more preferably 85% or more. When the gel fraction of the pressure-sensitive adhesive layer is small, the polymerization degree is poor, and when the gel fraction of the pressure-sensitive adhesive layer is too large, the adhesive force may be poor.

The transmission b, the transmission at a wavelength of 380nm, and the transmission at a wavelength of 400nm of the adhesive layer are as described above.

The adhesive layer of the present invention is used for an image display device, more specifically, between a protective glass or a protective plastic and a polarizing film in an image display device. By locating the adhesive layer of the present invention at this position, the ultraviolet absorption function can be sufficiently exhibited.

3. Polarizing film with adhesive layer

The polarizing film with an adhesive layer of the present invention is characterized by comprising a polarizing film and the ultraviolet-curable acrylic adhesive layer on at least one surface of the polarizing film.

As described above, the method for forming the ultraviolet-curable acrylic pressure-sensitive adhesive layer may be a method in which the ultraviolet-curable acrylic pressure-sensitive adhesive composition is directly applied to the polarizing film to form the pressure-sensitive adhesive layer, or a method in which the pressure-sensitive adhesive layer is formed on a release film or the like and then the pressure-sensitive adhesive layer is transferred to the polarizing film to form the pressure-sensitive adhesive layer on the polarizing film.

The polarizing film is preferably a polarizing film having a transparent protective film on at least one surface of a polarizer.

The polarizer is not particularly limited, and various polarizers may be used. Examples of the polarizer include: a polarizer obtained by uniaxially stretching a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene-vinyl acetate copolymer partially saponified film, after adsorbing a dichromatic substance such as iodine or a dichromatic dye, or a polyolefin-based alignment film such as a dehydrated polyvinyl alcohol or a dehydrochlorinated polyvinyl chloride. Among them, a polarizer containing a polyvinyl alcohol film and a dichroic substance such as iodine is preferable. The thickness of these polarizers is not particularly limited, and is generally about 5 μm to about 80 μm.

The polarizer obtained by uniaxially stretching a polyvinyl alcohol film dyed with iodine can be produced, for example, by immersing polyvinyl alcohol in an aqueous iodine solution, dyeing the film, and stretching the film to 3 to 7 times the original length. The coating composition may be immersed in an aqueous solution of potassium iodide or the like which may optionally contain boric acid, zinc sulfate, zinc chloride or the like. Further, the polyvinyl alcohol film may be washed with water by immersing it in water before dyeing, if necessary. The polyvinyl alcohol film can be washed with water to remove stains and an anti-blocking agent on the surface of the polyvinyl alcohol film, and in addition, the polyvinyl alcohol film can be swollen to prevent unevenness such as uneven dyeing. The stretching may be performed after dyeing with iodine, may be performed simultaneously with dyeing, and may be performed after the stretching with iodine. Stretching may be performed in an aqueous solution or water bath of boric acid, potassium iodide, or the like.

In the present invention, a thin polarizer having a thickness of 10 μm or less may be used. From the viewpoint of thinning, the thickness is preferably 1 μm to 7 μm. Such a thin polarizer is excellent in durability because of its small thickness unevenness, excellent visibility, and small dimensional change, and is preferable in terms of the thickness of the polarizing film and the reduction in thickness.

As a thin polarizer, there are typically mentioned: a thin polarizing film described in japanese patent laid-open nos. 51-069644, 2000-338329, 2010/100917, 4751481, 2012-073563. These thin polarizing films can be obtained by a production method including a step of stretching a polyvinyl alcohol resin (hereinafter, also referred to as PVA-based resin) layer and a stretching resin base material in a state of being laminated and a step of dyeing. With this production method, even if the PVA-based resin layer is thin, it can be stretched without causing problems such as breakage due to stretching by being supported by the stretching resin base material.

As the thin polarizing film, from the viewpoint that the polarizing performance can be improved by stretching at a high magnification even in a manufacturing method including a step of stretching in a state of a laminate and a step of dyeing, a polarizing film obtained by a manufacturing method including a step of stretching in an aqueous boric acid solution as described in international publication No. 2010/100917 unistrand, or japanese patent No. 4751481 and japanese patent No. 2012 and 073563, and particularly a polarizing film obtained by a manufacturing method including a step of stretching in air auxiliarily before stretching in an aqueous boric acid solution as described in japanese patent No. 4751481 and japanese patent No. 2012 and 073563, is preferable.

As a material for forming the transparent protective film provided on one or both sides of the polarizer, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like is preferable. Examples thereof include: polyester polymers such AS polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such AS diacetylcellulose and triacetylcellulose, acrylic polymers such AS polymethyl methacrylate, styrene polymers such AS polystyrene and acrylonitrile-styrene copolymer (AS resin), and polycarbonate polymers. Examples of the polymer forming the transparent protective film include polyethylene, polypropylene, polyolefin having a cyclic or norbornene structure, polyolefin polymers such as ethylene-propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers, polyethersulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, aromatic ester polymers, polyacetal polymers, epoxy polymers, and blends of the above polymers. The transparent protective film may be formed as a cured layer of a heat-curable or ultraviolet-curable resin such as acrylic, polyurethane, acrylic polyurethane, epoxy, or polysiloxane.

The thickness of the protective film may be appropriately determined, and is usually about 1 μm to about 500 μm in view of strength, workability such as handling property, thin film property, and the like.

The polarizer and the protective film are generally adhered via an aqueous adhesive or the like. Examples of the aqueous adhesive include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl emulsions, aqueous polyurethanes, and aqueous polyesters. In addition to the above, examples of the adhesive for the polarizer and the transparent protective film include an ultraviolet-curable adhesive, an electron beam-curable adhesive, and the like. The adhesive for electron beam-curable polarizing films exhibited suitable adhesiveness to the various transparent protective films described above. The adhesive used in the present invention may contain a metal compound filler.

The side of the transparent protective film that is not adhered to the polarizer may be subjected to a hard coating treatment, an antireflection treatment, a treatment for the purpose of blocking prevention, diffusion, or antiglare.

In the case where the pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer-equipped polarizing film of the present invention is exposed, the pressure-sensitive adhesive layer may be protected with a release film (separator) until it is practically used. The release film may be the one described above. When a release film is used as a substrate in the production of the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer on the release film is bonded to the polarizing film, whereby the release film can be used as a release film for the pressure-sensitive adhesive layer of the polarizing film with a pressure-sensitive adhesive layer, and the process can be simplified.

4. Method for producing adhesive layer

The present invention relates to a method for producing an ultraviolet-curable acrylic pressure-sensitive adhesive layer, which is a method for producing a pressure-sensitive adhesive layer formed from an ultraviolet-curable acrylic pressure-sensitive adhesive composition containing a photopolymerization initiator (B),

it is characterized in that the preparation method is characterized in that,

The components constituting the ultraviolet-curable acrylic pressure-sensitive adhesive composition are as described above.

In the case where the pressure-sensitive adhesive layer is formed from an ultraviolet-curable acrylic pressure-sensitive adhesive composition containing a photopolymerization initiator (B), a composition containing a monomer component containing an alkyl (meth) acrylate and the photopolymerization initiator (B) (which may be referred to as "polymerization initiator added first") is first irradiated with ultraviolet rays to form a partial polymer of the monomer component. The polymerization rate of the partial polymer is preferably about 20% or less, more preferably about 3% to about 20%, and still more preferably about 5% to about 15%. The conditions for ultraviolet irradiation were as described above.

Next, an ultraviolet absorber and a photopolymerization initiator (a) having an absorption band at a wavelength of 400nm or more (also referred to as "post-addition polymerization initiator") are added to a partial polymer of the monomer component to prepare an ultraviolet-curable acrylic pressure-sensitive adhesive composition. The ultraviolet absorber, the photopolymerization initiator (A) having an absorption band at a wavelength of 400nm or more, and the amounts of addition thereof are as described above.

The ultraviolet-curable acrylic pressure-sensitive adhesive layer can be produced by applying the ultraviolet-curable acrylic pressure-sensitive adhesive composition obtained in this manner to at least one surface of a substrate and irradiating the ultraviolet-curable acrylic pressure-sensitive adhesive composition with ultraviolet rays. The conditions for ultraviolet irradiation were as described above.

The substrate is not particularly limited, and various substrates such as a release film and a transparent resin film substrate can be exemplified, and a polarizing film described later can be suitably used as the substrate.

Examples of the constituent material of the release film include: resin films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films; porous materials such as paper, cloth, and nonwoven fabric; a resin film is preferably used for a thin sheet (a "Yeye"), such as a web, a foam sheet, a metal foil, or a laminate thereof, from the viewpoint of excellent surface smoothness.

Examples of the resin film include: polyethylene films, polypropylene films, polybutylene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polyethylene terephthalate films, polybutylene terephthalate films, polyurethane films, ethylene-vinyl acetate copolymer films, and the like.

The thickness of the release film is generally about 5 μm to about 200 μm, preferably about 5 μm to about 100 μm. The release film may be subjected to release and anti-fouling treatment with a silicone, fluorine-containing, long-chain alkyl or fatty acid amide release agent, silica powder or the like, or antistatic treatment such as coating type, kneading type, vapor deposition type or the like, as required. In particular, by appropriately subjecting the surface of the release film to a release treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment, the releasability from the pressure-sensitive adhesive layer can be further improved.

The transparent resin film substrate is not particularly limited, and various transparent resin films are used. The resin film is formed of one film. Examples of the material include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl alcohol resins, polyarylate resins, and polyphenylene sulfide resins. Among these, polyester resins, polyimide resins, and polyether sulfone resins are particularly preferable.

The thickness of the film substrate is preferably 15 to 200 μm, and more preferably 25 to 188 μm.

The method for applying the ultraviolet-curable acrylic pressure-sensitive adhesive composition to the substrate may be any known suitable method such as a roll coater, a bar coater, or a die coater, and is not particularly limited.

Since the reaction is inhibited by oxygen in the air, it is preferable to form a release film or the like on the coating layer of the acrylic adhesive composition or to perform a photopolymerization reaction in a nitrogen atmosphere in order to block oxygen. The release film may be the one described above.

As described above, when the pressure-sensitive adhesive layer is formed from the ultraviolet-curable acrylic pressure-sensitive adhesive composition containing the photopolymerization initiator (B), it is preferable that: the ultraviolet-curable acrylic pressure-sensitive adhesive composition is produced by first adding a photopolymerization initiator (B) to form a partial polymer of the monomer component, and then adding an ultraviolet absorber and a photopolymerization initiator (a) having an absorption band at a wavelength of 400nm or more to the partial polymer. By performing the polymerization in two stages in this manner, the polymerization rate of the monomer component can be increased, and the ultraviolet absorption function of the pressure-sensitive adhesive layer to be finally produced can be improved.

5. Image display device

The image display device of the present invention is characterized in that the image display device has at least a protective glass or a protective plastic and a polarizing film, and

the image display device has the adhesive layer between the protective glass or protective plastic and a polarizing film.

The image display device has at least one polarizing film and at least one protective glass or protective plastic, and is specifically constituted as described above. Further, as the image display device, a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), an electronic paper, and the like can be cited, and among these, a liquid crystal display device, an organic EL (electroluminescence) display device, and the like having the above-described configuration are preferable.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In each example, parts and% are on a weight basis. Evaluation items in examples and the like were measured as described below.

Production example 1 (production of acrylic pressure-sensitive adhesive composition (a-1))

A monomer mixture comprising 78 parts by weight of 2-ethylhexyl acrylate (2EHA), 18 parts by weight of N-vinyl-2-pyrrolidone (NVP) and 4 parts by weight of 2-hydroxyethyl acrylate (HEA) was mixed with 0.035 part by weight of 1-hydroxycyclohexyl phenyl ketone (product name: Irgacure184, manufactured by BASF corporation) and 0.035 part by weight of 2, 2-dimethoxy-1, 2-diphenylethane-1-one (product name: Irgacure651, manufactured by BASF corporation) as a photopolymerization initiator (the photopolymerization initiator was added first), then, ultraviolet rays were irradiated until the viscosity (measurement conditions: BH viscometer, spindle No. 5, 10rpm, measurement temperature 30 ℃) became about 20 pas, whereby a prepolymer composition (polymerization rate: 8%) obtained by partially polymerizing the above monomer components was obtained. Then, 0.15 parts by weight of hexanediol diacrylate (HDDA) and 0.3 parts by weight of a silane coupling agent (trade name: KBM-403, manufactured by shin-Etsu chemical Co., Ltd.) were added to the prepolymer composition, and they were mixed and irradiated with ultraviolet light to obtain an acrylic pressure-sensitive adhesive composition (a-1).

Production example 2 (production of acrylic pressure-sensitive adhesive composition (a-2))

A partial polymer (monomer syrup) having a polymerization rate of 10% was obtained by partially photopolymerization by exposing 67 parts by weight of Butyl Acrylate (BA), 14 parts by weight of cyclohexyl acrylate (CHA), 19 parts by weight of 4-hydroxybutyl acrylate (4HBA), 0.09 part by weight of 2, 2-dimethoxy-1, 2-diphenylethan-1-one (trade name: Irgacure651, manufactured by BASF Japan) as a photopolymerization initiator and 0.09 part by weight of 1-hydroxycyclohexylphenylketone (trade name: Irgacure184, manufactured by BASF Japan) in a four-neck flask to ultraviolet light under a nitrogen atmosphere. Then, 0.15 parts by weight of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA) and 0.3 parts by weight of a silane coupling agent (trade name: KBM-403, manufactured by shin-Etsu chemical Co., Ltd.) were added to the partial polymer, and they were mixed and subjected to ultraviolet irradiation to obtain an acrylic pressure-sensitive adhesive composition (a-2).

Example 1

To the acrylic adhesive composition (a-1), 1.4 parts of 2, 4-bis- [ {4- (4-ethylhexyloxy) -4-hydroxy } -phenyl ] -6- (4-methoxyphenyl) -1,3, 5-triazine (trade name: Tinosorb S, manufactured by basf japan) dissolved in butyl acrylate so that the solid content becomes 15%, and 0.2 parts of bis (2,4, 6-trimethylbenzoyl) -phenylphosphine oxide (trade name: Irgacure819, manufactured by basf japan) as a polymerization initiator were added and stirred, thereby obtaining an ultraviolet-curable acrylic adhesive composition.

The ultraviolet-curable acrylic adhesive composition was applied to the surface of the release film subjected to the release treatment so that the thickness after the formation of the adhesive layer was 150 μm to form a coating layer, and then a release film was bonded to the surface of the coating layer. Then, at the illuminance: 6.5mW/cm²Light quantity: 1500mJ/cm²The coating layer is photo-cured by ultraviolet irradiation under the conditions of (1), thereby forming a pressure-sensitive adhesive sheet having a release film on both sides of the pressure-sensitive adhesive layer.

Examples 2 to 16, comparative examples 1 to 6

An ultraviolet-curable acrylic adhesive composition was prepared in the same manner as in example 1, except that the type of the acrylic adhesive composition used, the ultraviolet absorber, the type and amount of the photopolymerization initiator added later, and the thickness after the adhesive layer was formed were set as described in table 1, and thereby an adhesive sheet was formed. However, in comparative examples 5 and 6, as shown in table 2, since the solubility of the acrylic pressure-sensitive adhesive composition and the ultraviolet absorber was poor, the ultraviolet-curable acrylic pressure-sensitive adhesive composition was prepared, but the pressure-sensitive adhesive sheet was not formed.

In the context of table 1, the following,

a-1 represents the acrylic pressure-sensitive adhesive composition (a-1) obtained in production example 1,

a-2 represents the acrylic pressure-sensitive adhesive composition (a-2) obtained in production example 2,

tinosorb S represents 2, 4-bis [ {4- (4-ethylhexyloxy) -4-hydroxy } phenyl ] -6- (4-methoxyphenyl) -1,3, 5-triazine (manufactured by BASF corporation),

tinuvin928 represents 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3, 3-tetramethylbutyl) phenol (manufactured by BASF corporation),

LA-F70 represents 2,4, 6-tris (2-hydroxy-4-hexyloxy-3-methylphenyl) -1,3, 5-triazine (manufactured by Adedic (ADEKA)),

KEMISORB279 represents 2, 2' -methylenebis [6- (benzotriazol-2-yl) -4-tert-octylphenol ] (manufactured by Chemipro chemical Co., Ltd.),

irgacure 819: bis (2,4, 6-trimethylbenzoyl) phenylphosphine oxide (trade name, manufactured by basf japan corporation), having an absorption band in the wavelength range of 200nm to 450nm,

irgacure 651: 2, 2-dimethoxy-1, 2-diphenylethan-1-one (trade name, manufactured by BASF Japan) having an absorption band in a wavelength range of 200nm to 380nm,

irgacure 184: 1-hydroxycyclohexyl phenyl ketone (trade name, manufactured by BASF Japan) has an absorption band in a wavelength range of 200nm to 370 nm.

The obtained adhesive sheet was evaluated as follows.

< solubility >

The ultraviolet absorbers used in the examples and comparative examples in the parts shown in table 1 based on 100 parts by weight of the acrylic pressure-sensitive adhesive composition in the parts shown in table 1 were added, and the solubility was visually observed and evaluated according to the following evaluation criteria.

O: the ultraviolet absorber dissolves in the acrylic adhesive composition without insoluble residue.

X: the uv absorber produces an insoluble residue in the acrylic adhesive composition.

< polymerization Rate >

The double-sided release films of the pressure-sensitive adhesive sheets obtained in examples and comparative examples were peeled off, and only the pressure-sensitive adhesive layer was placed on an aluminum dish after weight measurement. The weight of (aluminum dish + adhesive layer) was measured to determine the weight of the adhesive layer before drying. After drying at 130 ℃ for 2 hours, the mixture was cooled at room temperature for about 20 minutes, and then the weight of the dried adhesive layer was measured again to determine the weight of the adhesive layer. The polymerization rate was obtained from the following calculation formula.

< gel fraction >

About 0.1g of the pressure-sensitive adhesive layers were selected from the pressure-sensitive adhesive sheets obtained in examples and comparative examples, and the pressure-sensitive adhesive layers were coated with a porous tetrafluoroethylene sheet (trade name: NTF1122, manufactured by Nindon electric corporation) having an average pore diameter of 0.2. mu.m, and then tied with kite strings, and the weight (Zg) at that time was measured and taken as the weight before immersion. The weight before impregnation is the total weight of the adhesive layer (the above-mentioned selected adhesive layer), the tetrafluoroethylene sheet and the kite string. In addition, the total weight (Yg) of the tetrafluoroethylene sheet and the kite string was measured. Subsequently, the adhesive layer (referred to as "sample") coated with the tetrafluoroethylene sheet and tied with the kite string was placed in a 50mL container filled with ethyl acetate, and allowed to stand at 23 ℃ for 7 days. Then, the sample was taken out from the vessel (after ethyl acetate treatment), transferred to an aluminum cup, dried in a desiccator at 130 ℃ for 2 hours, and ethyl acetate was removed, and then the weight (Xg) was measured and taken as the weight after immersion. The gel fraction was calculated from the following formula.

Gel fraction (% by weight) — (X-Y)/(Z-Y) × 100

< measurement of transmittance, b-value >

The pressure-sensitive adhesive sheets obtained in examples and comparative examples were peeled off from each other on both sides of the release film, and the pressure-sensitive adhesive layers were mounted on a measuring jig and measured by a spectrophotometer (product name: U4100, manufactured by Hitachi high tech Co., Ltd.).

< optical reliability of adhesive layer monomer >

The release films on both sides of the pressure-sensitive adhesive sheets obtained in examples and comparative examples were peeled off, and glass (trade name: S200200, thickness: 1.3mm, size: 45 mm. times.50 mm, manufactured by Songla Miao Kogyo Co., Ltd.) was bonded to both sides of the pressure-sensitive adhesive layer, and autoclave treatment (air pressure: 0.5MPa, temperature: 50 ℃ C.) was carried out for 15 minutes. The transmittance and the color tone after the respective input under the following various reliability conditions 1 to 5 were measured by U4100 (product name) manufactured by Hitachi high and New technology Co., Ltd, and the amount of change in transmittance from the initial value was obtained. Evaluation was performed according to the following evaluation criteria.

(conditions of various reliabilities)

(Condition 1)85 ℃ C.. times.500 hours

(Condition 2) -40 ℃ C.. times.500 hours

(Condition 3)60 ℃, 95%. times.500 hours

(Condition 4) Heat Shock (HS) (-40 ℃ to 85 ℃) multiplied by 300 cycles

(condition 5) UV irradiation × 100 hours, illuminance: 500W/cm²(300nm to 700nm), ambient temperature: 60-65 ℃, ambient humidity: 50 percent of

(evaluation criteria)

Very good: the change in transmittance is 0.2% or less.

O: the transmittance change amount is greater than 0.2% and 0.7% or less.

And (delta): the transmittance change amount is greater than 0.7% and 1.0% or less.

X: the transmission change amount is greater than 1.0%.

< visibility >

A polarizing film having a TAC film (25 μm) subjected to a hard coat treatment on one side of a polarizer having a thickness of 12 μm and an acrylic film (20 μm) on the other side of the polarizer was prepared. The pressure-sensitive adhesive sheets obtained in examples and comparative examples were peeled off from each other on both sides of the release film, and an adhesive layer was bonded to each protective film of the polarizing film, and further glass (trade name: S200200, thickness: 1.3mm, size: 45 mm. times.50 mm, manufactured by Songla Miao Kogyo Co., Ltd.) was bonded to each of the adhesive layers on both sides to prepare a measurement sample. The obtained measurement sample was autoclaved for 15 minutes (air pressure: 0.5MPa, temperature: 50 ℃ C.). The color tone was measured by an ultraviolet-visible near-infrared spectrophotometer (product name: V7100, manufactured by Nippon Kabushiki Kaisha) and evaluated by the following evaluation criteria.

Good: b value is 1.4 or more and 3.4 or less

And (delta): b value is more than 3.4 and less than 3.9

X: b value greater than 3.9

< durability >

The release films on both sides of the pressure-sensitive adhesive sheets obtained in examples and comparative examples were peeled offA glass (trade name: S200200, thickness: 1.3mm, size: 45 mm. times.50 mm, manufactured by Songlanzui Kogyo Co., Ltd.) was bonded to both sides of the adhesive layer to prepare a measurement sample. The obtained measurement sample was autoclaved for 15 minutes (air pressure: 0.5MPa, temperature: 50 ℃ C.). The mixture was charged under various reliability conditions shown in Table 1 (condition 1: 85 ℃ C. times.500 hours, condition 2: 40 ℃ C. times.500 hours, condition 3: 60 ℃ C. times.500 hours, condition 4: minor cycle, condition 5: UV irradiation × 100 hours), the evaluation sample is measured with a magnifying glass or an electron microscope. Evaluation was performed by the following evaluation criteria.

Good: no peeling and foaming from the end.

X: peeling and foaming occurred.

< UV resistance (protective function of polarizing film) >

A polarizing film having a thickness of 12 μm with one side of the polarizer protected by a TAC film (25 μm) subjected to a hard coat treatment and the other side of the polarizer protected by an acrylic film (20 μm) was prepared. The pressure-sensitive adhesive sheets obtained in examples and comparative examples were peeled from each other on both sides of a release film, and the pressure-sensitive adhesive layers were bonded to respective protective films of a polarizing film, and further, glass (trade name: S200200, thickness: 1.3mm, size: 45 mm. times.50 mm, manufactured by Songla Miao Kogyo Co., Ltd.) was bonded to the pressure-sensitive adhesive layers on both sides to prepare measurement samples. The obtained measurement sample was autoclaved for 15 minutes (air pressure: 0.5MPa, temperature: 50 ℃ C.). Then, the input was adjusted to the illuminance: 500W/cm²(300nm to 700nm), ambient temperature: 60-65 ℃, and ambient humidity: the amount of change in transmittance from the initial value was determined by measurement using an ultraviolet-visible near-infrared spectrophotometer (product name: V7100, manufactured by Nippon Kabushiki Kaisha) under 50% UV irradiation. Evaluation was performed according to the following evaluation criteria.

Very good: the change in transmittance is 1.0% or less.

O: the transmittance change amount is greater than 1.0% and 2.0% or less.

And (delta): the transmittance change amount is greater than 2.0% and 3.0% or less.

X: the transmission change amount is greater than 3.0%.

Reference numerals

1 protective glass or protective plastic

2a to 2c adhesive layer

3a, 3b protective film

4 polarizer

5 polarizing film

6 liquid crystal display device (LCD) or organic EL display device (OLED)

7 sensor layer

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Acrylic pressure-sensitive adhesive composition, pressure-sensitive adhesive layer and method for producing same, polarizing film with pressure-sensitive adhesive layer, and image display device

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