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

Abstract

The present invention relates to an acrylic adhesive composition, an adhesive layer, a method for manufacturing the same, a polarizing film with an 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 contains: 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 400 nm or more, and the transmittance of the adhesive layer formed from the adhesive composition at a wavelength of 380 nm is 40% or less, and the transmittance at a wavelength of 400 nm is 30% or more.

Description

[0001] This application is a divisional application of a Chinese patent application with an application date of June 15, 2016 and an application number of 201680086252.8. Technical Field

[0002] 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. Further, the present invention relates to an ultraviolet-curable acrylic adhesive layer formed from the ultraviolet-curable acrylic adhesive composition, a polarizing film with an adhesive layer having the ultraviolet-curable acrylic adhesive layer, a method for manufacturing the ultraviolet-curable acrylic 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 an electronic paper. Background Art

[0003] For liquid crystal display devices and organic EL display devices, etc., due to their image formation methods, for example, in a liquid crystal display device, it is essential to dispose polarizing elements on both sides of a liquid crystal cell, and a polarizing film is usually pasted. Further, in display panels such as a liquid crystal panel and an organic EL panel, various optical elements are also used in order to improve the display quality of the display device in addition to the polarizing film.

[0004] The polarizing film used in these image display devices generally has a configuration in which a polarizer is sandwiched between two protective films, and triacetyl cellulose (TAC) is widely used as the protective film.

[0005] In recent years, along with the trend of weight reduction and thinning of image display devices, each component used in an image display device is required to be thinned, and the protective film of the polarizing film is also required to be thinned. When the thickness of the protective film is thinned, it is impossible to sufficiently block ultraviolet rays incident on the image display device, and there is a problem that not only the deterioration of the polarizer caused by ultraviolet rays is accelerated, but also the deterioration of various optical members including a liquid crystal panel and an organic EL element used in the image display device caused by ultraviolet rays is accelerated.

[0006] In order to eliminate such problems, for example, the following are known: a transparent double-sided adhesive sheet for an image display device, the double-sided adhesive sheet being disposed between a surface protection panel and a visually recognizable side of a liquid crystal module in the image display device for integrating two members, wherein the double-sided adhesive sheet has at least one ultraviolet absorbing layer, the light transmittance of light with a wavelength of 380 nm is 30% or less, and the visible light transmittance on the longer wavelength side than 430 nm is 80% or more (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 ultraviolet absorbing ability can be imparted to the adhesive layer in an adhesive optical film having an adhesive layer provided on one or both sides of an optical film (for example, see Patent Document 3).

[0007] Prior Art Documents

[0008] Patent Documents

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-211305

[0010] Patent Document 2: Japanese Patent Application Laid-Open No. 2013-75978

[0011] Patent Document 3: Japanese Patent No. 4208187 Summary of the Invention

[0012] Problems to be Solved by the Invention

[0013] In the adhesive sheets of Patent Documents 1 and 2, the thickness of the adhesive layer containing the ultraviolet absorber is thin, so the ultraviolet absorption function is insufficient. In addition, due to the thin thickness of the adhesive layer, when unevenness (height difference) absorption is required, problems such as the occurrence of bubbles may sometimes occur. In these patent documents, when forming the adhesive layer containing the ultraviolet absorber, polymerization using ultraviolet irradiation is not performed, and of course, photoinitiators having an absorption band at 400 nm or more are not studied either.

[0014] In addition, in Patent Document 3, there is no specific study on forming an adhesive layer having an ultraviolet absorption function using a polymerization method using ultraviolet irradiation, and there is also no sufficient study on photoinitiators having an absorption band at 400 nm or more.

[0015] In addition, apart from Patent Documents 1 to 3, various transparent adhesives having an ultraviolet absorption function are also known. However, most of the currently known transparent adhesives having an ultraviolet absorption function are manufactured by solution polymerization of the base polymer of the adhesive. With such a manufacturing method, it is difficult to manufacture a relatively thick product of 150 μm or more, and there are limitations in the thickness of the adhesive layer that can be manufactured. It is known that an adhesive layer with a thick thickness can be formed in the case of using a polymerization method using ultraviolet irradiation, but at present, a method for forming an adhesive layer having an ultraviolet absorption function by a polymerization method using ultraviolet irradiation is not yet known.

[0016] Therefore, an object of the present invention is to provide an ultraviolet-curable acrylic adhesive composition capable of forming an adhesive layer having an ultraviolet absorption function by a polymerization method using ultraviolet irradiation. In addition, an object of the present invention is to provide an ultraviolet-curable acrylic adhesive layer formed from the ultraviolet-curable acrylic adhesive composition, a polarizing film with an adhesive layer having the ultraviolet-curable acrylic adhesive layer, a manufacturing method of the ultraviolet-curable acrylic adhesive layer, and an image display device.

[0017] Means for Solving the Problem

[0018] The present inventors conducted in-depth research to solve the above problems and, as a result, found the following ultraviolet-curable acrylic adhesive composition, thereby completing the present invention.

[0019] 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,

[0020] characterized in that,

[0021] the adhesive composition contains: a monomer component containing (meth)acrylic acid alkyl ester 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 400 nm or more, and

[0022] the transmittance of the adhesive layer formed from the adhesive composition at a wavelength of 380 nm is 40% or less, and the transmittance of the adhesive layer formed from the adhesive composition at a wavelength of 400 nm is 30% or more.

[0023] Preferably, the transmittance b* value of the adhesive layer is 3.0 or less.

[0024] Preferably, the ultraviolet absorber is at least one ultraviolet absorber selected from the group consisting of triazine-based ultraviolet absorbers having 2 or less hydroxyl groups in one molecule and benzotriazole-based ultraviolet absorbers having 1 benzotriazole skeleton in one molecule.

[0025] Preferably, the addition amount of the photopolymerization initiator (A) is less than the addition amount of the ultraviolet absorber.

[0026] Preferably, the ultraviolet curable acrylic adhesive composition of the present invention further contains a photopolymerization initiator (B) having an absorption band at a wavelength less than 400 nm.

[0027] The present invention relates to an ultraviolet curable acrylic adhesive layer which is an adhesive layer located between a protective glass or a protective plastic and a polarizing film in an image display device.

[0028] It is characterized in that

[0029] The ultraviolet curable acrylic adhesive layer is formed by irradiating the ultraviolet curable acrylic adhesive composition with ultraviolet rays to photopolymerize the monomer components in the ultraviolet curable acrylic adhesive composition.

[0030] The present invention relates to a polarizing film with an adhesive layer, which is characterized in that the polarizing film with an adhesive layer has a polarizing film and the ultraviolet curable acrylic adhesive layer on at least one surface of the polarizing film.

[0031] In addition, the present invention relates to a method for manufacturing an ultraviolet curable acrylic adhesive layer, which is a method for manufacturing an adhesive layer formed from an ultraviolet curable acrylic adhesive composition containing the photopolymerization initiator (B).

[0032] It is characterized in that

[0033] The manufacturing method includes: a step of irradiating a composition containing a monomer component containing (meth)acrylic acid alkyl ester and the photopolymerization initiator (B) with ultraviolet rays to form a partial polymer of the monomer component;

[0034] a step of adding an ultraviolet absorber and a photopolymerization initiator (A) having an absorption band at 400 nm or more to the partial polymer of the monomer component to produce an ultraviolet curable acrylic adhesive composition; and

[0035] a step of applying the ultraviolet curable acrylic adhesive composition to at least one side of a substrate and irradiating the ultraviolet curable acrylic adhesive composition with ultraviolet rays.

[0036] In addition, the present invention relates to an image display device having at least a protective glass or protective plastic and a polarizing film,

[0037] characterized in that,

[0038] the image display device has the ultraviolet-curable acrylic adhesive layer between the protective glass or protective plastic and the polarizing film.

[0039] Advantages of the Invention

[0040] The ultraviolet-curable acrylic adhesive composition of the present invention can form an adhesive layer having an ultraviolet absorption function by a polymerization method using ultraviolet irradiation, and thus can form an adhesive layer having a thickness of 150 μm or more and can form an adhesive layer having a wide thickness range. The adhesive layer of the present invention has excellent ultraviolet absorption function, and thus by using the adhesive layer for an image display device, deterioration of optical members including a liquid crystal panel, an organic EL element, a polarizer, etc. can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 is a cross-sectional view schematically showing an embodiment of the image display device of the present invention.

[0042] Figure 2 is a cross-sectional view schematically showing an embodiment of the image display device of the present invention.

[0043] Figure 3 is a cross-sectional view schematically showing an embodiment of the image display device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0044] 1. Ultraviolet-curable acrylic adhesive composition

[0045] The ultraviolet-curable acrylic adhesive composition of the present invention is used to form an adhesive layer between a protective glass or protective plastic and a polarizing film in an image display device,

[0046] characterized in that,

[0047] the adhesive composition contains: a monomer component containing (meth)acrylic acid alkyl ester 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 400 nm or more, and

[0048] the transmittance of the adhesive layer formed from the adhesive composition at a wavelength of 380 nm is 40% or less, and the transmittance of the adhesive layer formed from the adhesive composition at a wavelength of 400 nm is 30% or more.

[0049] Embodiments of an image display device including the adhesive layer of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments shown in the drawings.

[0050] As an example of the configuration of the image display device, for example, it can be cited as Figures 1 to 3 shown, such as

[0051] Protective glass or protective plastic 1 / Adhesive layer 2a / Polarizing film 5 / Liquid crystal display device (LCD) or Organic EL display device (OLED) 6;

[0052] Protective glass or protective plastic 1 / Adhesive layer 2b / Sensor layer 7 / Adhesive layer 2a / Polarizing film 5 / Liquid crystal display device (LCD) or Organic EL display device (OLED) 6;

[0053] Protective glass or protective plastic 1 / Adhesive layer 2b / Sensor layer 7 / Adhesive layer 2c / Sensor layer 7 / Adhesive layer 2a / Polarizing film 5 / Liquid crystal display device (LCD) or Organic EL display device (OLED) 6; and so on,

[0054] An image display device obtained by laminating each layer in sequence. In addition to these layers, a retardation film or the like can be appropriately added. Specifically, it can be laminated via an adhesive layer between the polarizing film 5 and the liquid crystal display device (LCD) or the organic EL display device (OLED) 6. In addition, an adhesive layer and / or an adhesive layer can be appropriately used in the lamination of each layer. It should be noted that Figures 1 to 3 The polarizing film 5 has a configuration in which a polarizer 4 is sandwiched between two protective films 3a and 3b, but it can also be a single-sided protective polarizing film in which the polarizer 4 is protected on one side with a protective film.

[0055] The adhesive layer containing the ultraviolet curable acrylic adhesive composition of the present invention is an adhesive layer located between the protective glass or protective plastic 1 in the image display device and the polarizing film 5 existing at a position closer to the visual recognition side than the liquid crystal display device (LCD) or the organic EL display device (OLED) 6, and can be located at Figures 1 to 3 any position among the adhesive layers 2a to 2c in. From the viewpoint of ultraviolet absorption ability, it is more preferable to use the adhesive layer of the present invention in the adhesive layer (2a in the figure) in contact with the polarizing film 5. By arranging the adhesive layer containing the ultraviolet curable acrylic adhesive composition of the present invention at the above position, it is possible to protect the polarizing film and the like in the image display device from the influence of ultraviolet rays incident from the visual recognition side in the image display device, and thus it is preferable.

[0056] 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 400 nm or more.

[0057] Examples of the alkyl (meth)acrylate include alkyl (meth)acrylates having a linear or branched alkyl group with 1 to 24 carbon atoms at the ester terminal. The alkyl (meth)acrylate may be used alone or in combination of two or more. It should be noted that the alkyl (meth)acrylate refers to an alkyl acrylate and / or an alkyl methacrylate, and the "(meth)" in the present invention has the same meaning.

[0058] Examples of the alkyl (meth)acrylate include alkyl (meth)acrylates having a branched alkyl group with 4 to 9 carbon atoms at the ester terminal. From the aspect of easily obtaining a balance of adhesive properties, this alkyl (meth)acrylate is preferred. Specifically, examples include 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, etc. They may be used alone or in combination of two or more.

[0059] In the present invention, relative to the total amount of the monofunctional monomer component forming the (meth)acrylic polymer, the alkyl (meth)acrylate having an alkyl group with 1 to 24 carbon atoms at the ester terminal is preferably 40% by weight or more, more preferably 50% by weight or more, and still more preferably 60% by weight or more.

[0060] In the monomer component forming the (meth)acrylic polymer, a comonomer other than the alkyl (meth)acrylate may be contained as a monofunctional monomer component. The comonomer may be used as the remaining part of the monomer component other than the alkyl (meth)acrylate.

[0061] As a comonomer, for example, a cyclic nitrogen-containing monomer may be included. As the above-mentioned cyclic nitrogen-containing monomer, a monomer having a polymerizable functional group having an unsaturated double bond such as (meth)acryloyl or vinyl and having a cyclic nitrogen structure can be used without particular limitation. The cyclic nitrogen structure preferably has a nitrogen atom in the cyclic structure. As the cyclic nitrogen-containing monomer, for example, lactam-based vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone can be mentioned; vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyl oxazole, vinylmorpholine and other vinyl monomers having a nitrogen-containing heterocycle, etc. In addition, (meth)acrylic acid monomers containing heterocycles such as a morpholine ring, a piperidine ring, a pyrrolidine ring, and a piperazine ring can be mentioned. Specifically, N-acrylylmorpholine, N-acrylpiperidine, N-methylacrylylpiperidine, N-acrylylpyrrolidine, etc. can be mentioned. Among the cyclic nitrogen-containing monomers, lactam-based vinyl monomers are preferred.

[0062] In the present invention, relative to the total amount of the monofunctional monomer component forming the (meth)acrylic polymer, the cyclic nitrogen-containing monomer is preferably 0.5% by weight to 50% by weight, more preferably 0.5% by weight to 40% by weight, and still more preferably 0.5% by weight to 30% by weight.

[0063] The monomer component used in the present invention may include a hydroxyl-containing monomer as a monofunctional monomer component. As the hydroxyl-containing monomer, a monomer having a polymerizable functional group having an unsaturated double bond such as (meth)acryloyl or vinyl and having a hydroxyl group can be used without particular limitation. As the hydroxyl-containing monomer, for example, 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, 12-hydroxylauryl (meth)acrylate and other (meth)acrylic acid hydroxyalkyl esters can be mentioned; (meth)acrylic acid hydroxyalkyl cycloalkyl esters such as (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. In addition, hydroxyethyl (meth)acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol mono vinyl ether, etc. can be mentioned. These hydroxyl-containing monomers can be used alone or in combination. Among them, (meth)acrylic acid hydroxyalkyl esters are preferred.

[0064] In the present invention, from the aspect of improving the adhesive strength and cohesion, the above-mentioned hydroxyl group-containing monomer is preferably 1% by weight or more, more preferably 2% by weight or more, and still more preferably 3% by weight or more, relative to the total amount of the monofunctional monomer components forming the (meth)acrylic polymer. On the other hand, when the amount of the above-mentioned hydroxyl group-containing monomer is excessive, the adhesive layer may become hard and the adhesive strength may decrease. In addition, the viscosity of the adhesive may be too high or gelation may occur. Therefore, the above-mentioned 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, relative to the total amount of the monofunctional monomer components forming the (meth)acrylic polymer.

[0065] In addition, other functional group-containing monomers can be contained as monofunctional monomers in the monomer components for forming the (meth)acrylic polymer. For example, carboxyl group-containing monomers and monomers having a cyclic ether group can be cited.

[0066] As the carboxyl group-containing monomer, a monomer containing a polymerizable functional group having an unsaturated double bond such as (meth)acryloyl or vinyl and having a carboxyl group can be used without particular limitation. As the carboxyl group-containing monomer, for example, (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc. can be cited. These carboxyl group-containing monomers can be used alone or in combination. For itaconic acid and maleic acid, their acid anhydrides can be used. Among them, acrylic acid and methacrylic acid are preferred, and acrylic acid is particularly preferred. It should be noted that the carboxyl group-containing monomer can be optionally used in the monomer components used in the production of the (meth)acrylic polymer. On the other hand, the carboxyl group-containing monomer can also not be used.

[0067] As the monomer having a cyclic ether group, a monomer containing a polymerizable functional group having an unsaturated double bond such as (meth)acryloyl or vinyl and having a cyclic ether group such as an epoxy group or an oxetanyl group can be used without particular limitation. As the epoxy group-containing monomer, for example, glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 4-hydroxybutyl glycidyl ether (meth)acrylate, etc. can be cited. As the oxetanyl group-containing monomer, for example, 3-oxetanylmethyl (meth)acrylate, 3-methyl-3-oxetanylmethyl (meth)acrylate, 3-ethyl-3-oxetanylmethyl (meth)acrylate, 3-butyl-3-oxetanylmethyl (meth)acrylate, 3-hexyl-3-oxetanylmethyl (meth)acrylate, etc. can be cited. These monomers having a cyclic ether group can be used alone or in combination.

[0068] In the present invention, relative to the total amount of the monofunctional monomer component forming the (meth)acrylic polymer, the above 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.

[0069] Among the monomer components forming the (meth)acrylic polymer, as comonomers, for example, those represented by CH 2 =C(R 1 )COOR 2 (wherein the above R 1 represents hydrogen or methyl, and R 2 represents a substituted alkyl group having 1 to 3 carbon atoms or a cyclic cycloalkyl group) are (meth)acrylic acid alkyl esters.

[0070] Herein, the substituent of the substituted alkyl group having 1 to 3 carbon atoms for R 2 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 preferred.

[0071] Examples of such monomers represented by CH 2 =C(R 1 )COOR 2 include phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, etc. These monomers can be used alone or in combination.

[0072] In the present invention, relative to the total amount of the monofunctional monomer component forming the (meth)acrylic polymer, the (meth)acrylate represented by the above CH 2 =C(R 1 )COOR 2 can be used in an amount of 50% by weight or less, preferably 45% by weight or less, more preferably 40% by weight or less, and still more preferably 35% by weight or less.

[0073] As other comonomers, vinyl acetate, vinyl propionate, styrene, α-methylstyrene can also be used; diol acrylate monomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate; acrylate monomers such as tetrahydrofurfuryl (meth)acrylate, fluoro (meth)acrylate, polysiloxane (meth)acrylate, 2-methoxyethyl acrylate; amide group-containing monomers, amino group-containing monomers, imide group-containing monomers, N-acryloylmorpholine, vinyl ether monomers, etc. In addition, as comonomers, monomers having a cyclic structure such as terpene (meth)acrylate and (meth)acrylic acid tetrahydrodicyclopentadienyl ester can be used.

[0074] In addition, silane monomers containing silicon atoms can be cited, etc. As silane monomers, for example, 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloxydecyltrimethoxysilane, 10-acryloxydecyltrimethoxysilane, 10-methacryloxydecyltriethoxysilane, 10-acryloxydecyltriethoxysilane, etc. can be cited.

[0075] In the monomer component forming the (meth)acrylic polymer, in addition to the monofunctional monomers exemplified above, polyfunctional monomers can be contained as needed to adjust the cohesion of the adhesive.

[0076] The polyfunctional monomer is a monomer having at least two polymerizable functional groups having an unsaturated double bond such as (meth)acryloyl or vinyl. For example, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol 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, tetramethylolmethane tri(meth)acrylate and other ester compounds of polyhydric alcohols and (meth)acrylic acid; allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butanediol di(meth)acrylate, hexanediol di(meth)acrylate, etc. Among them, trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, and dipentaerythritol hexa(meth)acrylate can be preferably used. The polyfunctional monomers can be used alone or in combination of two or more.

[0077] The amount of the polyfunctional monomer used varies depending on its molecular weight, the number of functional groups, etc. With respect to 100 parts by weight in total of the monofunctional monomers, it 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. In addition, there is no particular limitation as the lower limit value, and it is preferably 0 part by weight or more, more preferably 0.001 part by weight or more. By using the polyfunctional monomer in the above range, the adhesive strength can be improved.

[0078] In the present invention, it may be a partial polymer of the monomer component. Herein, the so-called "partial polymer" is a polymer obtained by polymerizing a part of the monomer component. The polymerization rate of the partial polymer of the monomer component is as described below.

[0079] The ultraviolet curable acrylic adhesive composition of the present invention contains an ultraviolet absorber.

[0080] There is no particular limitation as the ultraviolet absorber, and examples thereof include: triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, hydroxybenzophenone-based ultraviolet absorbers, salicylate-based ultraviolet absorbers, cyanoacrylate-based ultraviolet absorbers, etc. These ultraviolet absorbers may be used alone or in combination of two or more. Among them, triazine-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers are preferred, and at least one ultraviolet absorber selected from the group consisting of a triazine-based ultraviolet absorber having two or less hydroxyl groups in one molecule and a benzotriazole-based ultraviolet absorber having one benzotriazole skeleton in one molecule is preferred because of its good solubility in the monomers used in the formation of the ultraviolet curable acrylic adhesive composition and its high ultraviolet absorption ability near a wavelength of 380 nm.

[0081] Specifically, as the triazine-based ultraviolet absorber having two or less hydroxyl groups in one molecule, 2,4-bis[{4-(4-ethylhexyloxy)-4-hydroxy}phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (Tinosorb S, manufactured by BASF); 2,4-bis[2-hydroxy-4-butoxyphenyl]-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 -C 16 (mainly C 12 -C 13) Reaction products of [[[alkyl]]oxy)methyl]oxirane (TINUVIN 400, manufactured by BASF); 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-[3-([[dodecyl]]oxy)-2-hydroxypropoxy]phenol), reaction product of 2-(2,4-dihydroxyphenyl)-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine and glycidic acid 2-ethylhexyl ester (TINUVIN 405, manufactured by BASF); 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[[(hexyl)oxy]]phenol (TINUVIN 1577, manufactured by BASF); 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]phenol (ADK STAB LA46, manufactured by ADEKA Corporation); 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (TINUVIN 479, manufactured by BASF Corporation), etc.

[0082] In addition, as benzotriazole-based ultraviolet absorbers having a benzotriazole skeleton in one molecule, the following can be used: 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN 928, manufactured by BASF), 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (TINUVIN PS, manufactured by BASF), an ester compound of phenylpropionic acid and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy (C7-9 side chain and straight-chain alkyl) (TINUVIN 384-2, manufactured by BASF); 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN 900, manufactured by BASF); 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN 928, manufactured by BASF); a reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate / polyethylene glycol 300 (TINUVIN 1130, manufactured by BASF); 2-(2H-benzotriazol-2-yl)cresol (TINUVIN P, manufactured by BASF); 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN 234, manufactured by BASF); 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-tert-butylphenol (TINUVIN 326, manufactured by BASF); 2-(2H-benzotriazol-2-yl)-4,6-ditert-amylphenol (TINUVIN 328, manufactured by BASF); 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN 329, manufactured by BASF); a reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 (TINUVIN 213, manufactured by BASF); 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-cresol (TINUVIN 571, manufactured by BASF); 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimidomethyl)-5-methylphenyl]benzotriazole (Sumisorb 250, manufactured by Sumitomo Chemical Co., Ltd.), etc.

[0083] In addition, examples of the benzophenone-based ultraviolet absorbers (benzophenone-based compounds) and hydroxybenzophenone-based ultraviolet absorbers (hydroxybenzophenone-based compounds) include: 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydrous salt and trihydrate), 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, and the like.

[0084] In addition, examples of the salicylate-based ultraviolet absorbers (salicylate-based compounds) include: phenyl 2-acryloyloxybenzoate, 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 (TINUVIN 120, manufactured by BASF), and the like.

[0085] Examples of the cyanoacrylate-based ultraviolet absorbers (cyanoacrylate-based compounds) include: alkyl 2-cyanoacrylate, cycloalkyl 2-cyanoacrylate, alkoxyalkyl 2-cyanoacrylate, alkenyl 2-cyanoacrylate, alkynyl 2-cyanoacrylate, and the like.

[0086] The ultraviolet absorber can be used alone or in combination of two or more. Relative to 100 parts by weight of the monofunctional monomer component forming the (meth)acrylic polymer, the total content is preferably about 0.1 part by weight to about 5 parts by weight, more preferably about 0.5 part by weight to about 3 parts by weight. By setting the addition amount of the ultraviolet absorber within the above range, the ultraviolet absorption function of the adhesive layer can be fully exerted without hindering ultraviolet polymerization, so it is preferred.

[0087] The ultraviolet curable acrylic adhesive composition of the present invention contains a photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more. The photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more only needs to have an absorption band at a wavelength of 400 nm or more, and may also have an absorption band at a wavelength less than 400 nm. When ultraviolet polymerization is carried out in the case where an ultraviolet absorber is contained in the adhesive composition, the ultraviolet rays are absorbed by the ultraviolet absorber and polymerization cannot be sufficiently carried out. However, since the adhesive composition of the present invention has a photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more, polymerization can be sufficiently carried out even though an ultraviolet absorber is contained.

[0088] Examples of the photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Irgacure 819, manufactured by BASF), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (LUCIRIN TPO, manufactured by BASF), and the like.

[0089] The photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more can be used alone or in combination of two or more.

[0090] In addition, there is no particular limitation on the addition amount of the photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more, and it is preferably less than the addition amount of the ultraviolet absorber. Relative to 100 parts by weight of the monofunctional monomer component forming the (meth)acrylic polymer, it is preferably about 0.005 parts by weight to about 1 part by weight, more preferably about 0.02 parts by weight to about 0.5 parts by weight. By the addition amount of the photopolymerization initiator (A) being within the above range, ultraviolet polymerization can be sufficiently carried out, so it is preferred.

[0091] In addition, a photopolymerization initiator (B) having an absorption band at a wavelength less than 400 nm may be contained in the ultraviolet curable acrylic adhesive composition of the present invention. In addition, the photopolymerization initiator (B) preferably does not have an absorption band at a wavelength of 400 nm or more. As the photopolymerization initiator (B), as long as it is a photopolymerization initiator that generates free radicals under ultraviolet light and initiates photopolymerization and has an absorption band at a wavelength less than 400 nm, there is no particular limitation, and any one of the commonly used photopolymerization initiators can be appropriately used. For example, benzoin ether type photopolymerization initiators, acetophenone type photopolymerization initiators, α-ketol type photopolymerization initiators, photoactive oxime type photopolymerization initiators, benzoin type photopolymerization initiators, benzil type photopolymerization initiators, benzophenone type photopolymerization initiators, ketal type photopolymerization initiators, thioxanthone type photopolymerization initiators, acylphosphine oxide type photopolymerization initiators, etc. can be used.

[0092] Specifically, as benzoin ether-based photoinitiators, examples include: benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one, anisoin methyl ether, and the like.

[0093] As acetophenone-based photoinitiators, examples include: 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, 4-tert-butyldichloroacetophenone, and the like.

[0094] As α-ketol-based photoinitiators, examples include: 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-hydroxy-2-methylpropan-1-one, and the like.

[0095] As photoactive oxime-based photoinitiators, examples include: 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)oxime, and the like.

[0096] As benzoin-based photoinitiators, examples include benzoin.

[0097] As benzil-based photoinitiators, examples include benzil.

[0098] Examples of benzophenone-based photoinitiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like.

[0099] Examples of ketal-based photoinitiators include benzil dimethyl ketal.

[0100] Examples of thioxanthone-based photoinitiators include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, and the like.

[0101] Examples of acylphosphine oxide-based photoinitiators include 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and the like.

[0102] The above-mentioned photopolymerization initiator (B) having an absorption band at a wavelength less than 400 nm can be used alone or in combination of two or more. The above-mentioned photopolymerization initiator (B) having an absorption band at a wavelength less than 400 nm can be added within the range that does not impair the effects of the present invention. As the addition amount, it is preferably about 0.005 parts by weight to about 0.5 parts by weight, more preferably about 0.02 parts by weight to about 0.1 parts by weight, based on 100 parts by weight of the monofunctional monomer component forming the (meth)acrylic polymer.

[0103] In the present invention, it is preferred that: first, the photopolymerization initiator (B) having an absorption band at a wavelength less than 400 nm is added to the monomer component, and ultraviolet rays are irradiated to polymerize a part to obtain a partial polymer (prepolymer composition) of the monomer component, and then the photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more and an ultraviolet absorber are added to the prepolymer composition for ultraviolet polymerization. When adding the photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more to the partial polymer (prepolymer composition) of the monomer component obtained by partial polymerization by ultraviolet irradiation, it is preferred to dissolve the photopolymerization initiator in the monomer and then add it.

[0104] In addition, the ultraviolet curable acrylic adhesive composition of the present invention may contain a silane coupling agent. The compounding amount of the silane coupling agent is preferably 1 part by weight or less, more preferably 0.01 part by weight to 1 part by weight, and further preferably 0.02 part by weight to 0.6 part by weight, based on 100 parts by weight of the monofunctional monomer component forming the (meth)acrylic polymer.

[0105] Examples of the silane coupling agent include: epoxy group-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 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-dimethylbutyl)propylamine, N-phenyl-γ-aminopropyltrimethoxysilane; (meth)acryloyl group-containing silane coupling agents such as 3-acryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane; isocyanate group-containing silane coupling agents such as 3-isocyanatopropyltriethoxysilane, etc.

[0106] The ultraviolet curable acrylic adhesive composition of the present invention may contain a crosslinking agent. Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, polysiloxane-based crosslinking agents, Crosslinking agents such as oxazoline crosslinking agents, aziridine crosslinking agents, silane crosslinking agents, alkyl etherified melamine crosslinking agents, metal chelate crosslinking agents, peroxides, etc. The crosslinking agents can be used alone or in combination of two or more. Among them, isocyanate crosslinking agents are preferably used.

[0107] The above crosslinking agents can be used alone or in combination of two or more. Relative to 100 parts by weight of the monofunctional monomer component forming the (meth)acrylic polymer, the content as a whole is preferably 5 parts by weight or less, more preferably 0.01 part by weight to 5 parts by weight, further preferably 0.01 part by weight to 4 parts by weight, and particularly preferably 0.02 part by weight to 3 parts by weight.

[0108] Isocyanate crosslinking agents refer to compounds having two or more isocyanate groups in one molecule (including isocyanate regenerable functional groups in which the isocyanate groups are temporarily protected by a blocking agent or polymerization). Examples of isocyanate crosslinking agents include aromatic isocyanates such as toluene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

[0109] More specifically, for example, lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate can be mentioned; alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate; aromatic diisocyanates such as 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, benzenedimethylene diisocyanate, and polymethylene polyphenyl isocyanate; isocyanate adducts such as trimethylolpropane / toluene diisocyanate trimer adduct (trade name: CORONATE L, manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane / hexamethylene diisocyanate trimer adduct (trade name: CORONATE HL, manufactured by Nippon Polyurethane Industry Co., Ltd.), and the isocyanurate form of hexamethylene diisocyanate (trade name: CORONATE HX, manufactured by Nippon Polyurethane Industry Co., Ltd.), benzenedimethylene diisocyanate trimethylolpropane adduct (trade name: D110N, manufactured by Mitsui Chemicals, Inc.), hexamethylene diisocyanate trimethylolpropane adduct (trade name: D160N, manufactured by Mitsui Chemicals, Inc.); polyether polyisocyanates, polyester polyisocyanates, and their adducts with various polyols, and polyisocyanates obtained by polyfunctionalization using isocyanurate bonds, biuret bonds, urethane bonds, etc.

[0110] In the ultraviolet-curable acrylic adhesive composition of the present invention, in addition to the above components, appropriate additives can be included according to the use. For example, the following can be cited: tackifiers (substances that are solid, semi-solid or liquid at room temperature, such as those containing rosin derivative resins, polyterpene resins, petroleum resins, oil-soluble phenolic resins, etc.); fillers such as hollow glass microspheres; plasticizers; anti-aging agents; antioxidants, etc.

[0111] In the present invention, it is preferable to adjust the viscosity of the above ultraviolet-curable acrylic adhesive composition to a viscosity suitable for operations such as coating on a substrate. The viscosity adjustment of the ultraviolet-curable acrylic adhesive composition is carried out, for example, by adding various polymers such as thickening additives, polyfunctional monomers, etc., or by partially polymerizing the monomer components in the ultraviolet-curable acrylic adhesive composition. It should be noted that this partial polymerization can be carried out before adding various polymers such as thickening additives, polyfunctional monomers, etc., or can be carried out thereafter. The viscosity of the above ultraviolet-curable acrylic adhesive composition varies according to the amount of additives, etc., so the polymerization rate when partially polymerizing the monomer components in the ultraviolet-curable acrylic adhesive composition cannot be uniquely determined. As a rough standard, it is preferably about 20% or less, more preferably about 3% to about 20%, and further preferably about 5% to about 15%. When it is greater than 20%, the viscosity becomes too high, so it is difficult to coat on the substrate.

[0112] There is no particular limitation on the transmission b* value of the adhesive layer formed by the ultraviolet-curable acrylic adhesive composition of the present invention, and it is preferably 3.0 or less, more preferably 1.5 or less, and further preferably 0.5 or less. The above b* value refers to the b* value (chromaticity) in the L*a*b* color system according to JIS Z8729, and can be measured, for example, using a spectrophotometer (product name: U4100, manufactured by Hitachi High-Technologies Corporation).

[0113] The transmittance of the adhesive layer formed by the ultraviolet-curable acrylic adhesive composition of the present invention at a wavelength of 380 nm is 40% or less, preferably 20% or less, and more preferably 8% or less. By having the transmittance at a wavelength of 380 nm within the above range, the incident ultraviolet rays can be sufficiently blocked, so the deterioration of optical members including liquid crystal panels, organic EL elements, polarizers, etc. can be suppressed.

[0114] In addition, the transmittance of the adhesive layer formed by the ultraviolet-curable acrylic adhesive composition of the present invention at a wavelength of 400 nm is 30% or more, preferably 50% or more, and more preferably 70% or more. By having the transmittance at a wavelength of 400 nm within the above range, the incident visible light can be sufficiently transmitted, and sufficient visual recognition can be ensured in an image display device, so it is preferable.

[0115] 2. UV - curable acrylic adhesive layer

[0116] The UV - curable acrylic adhesive layer of the present invention is characterized in that the adhesive layer is located between the protective glass or protective plastic and the polarizing film in the image display device, and

[0117] the adhesive layer is formed by irradiating the UV - curable acrylic adhesive composition with ultraviolet light to cause photopolymerization of the monomer components in the UV - curable acrylic adhesive composition.

[0118] For the UV - curable acrylic adhesive composition, the above - mentioned composition can be used.

[0119] The illuminance of the ultraviolet light irradiating the UV - curable acrylic adhesive composition is preferably 5 mW / cm 2 or more. When the illuminance of this ultraviolet light is less than 5 mW / cm 2 , the polymerization reaction time becomes long, and sometimes the productivity is poor. It should be noted that the illuminance of this ultraviolet light is preferably 200 mW / cm 2 or less. When the illuminance of this ultraviolet light is greater than 200 mW / cm 2 , the photoinitiator is rapidly consumed, so sometimes the polymer is depolymerized, especially the holding force at high temperature is reduced. In addition, the cumulative light amount of the ultraviolet light is preferably 100 mJ / cm 2 ~5000 mJ / cm 2 .

[0120] The ultraviolet lamp used in the present invention is not particularly limited, and an LED lamp is preferred. Compared with other ultraviolet lamps, the LED lamp is a lamp that releases less heat, so it can suppress the temperature during the polymerization of the adhesive layer. Therefore, it can prevent the depolymerization of the polymer, prevent the reduction of the cohesion of the adhesive layer, and can improve the holding force at high temperature when making an adhesive sheet. In addition, multiple ultraviolet lamps can also be combined. In addition, ultraviolet light can also be irradiated intermittently, setting a light period of irradiating ultraviolet light and a dark period of not irradiating ultraviolet light.

[0121] In the present invention, the final polymerization rate of the monomer components in the UV - curable acrylic adhesive composition is preferably 90% or more, more preferably 95% or more, and further preferably 98% or more.

[0122] In the present invention, the peak wavelength of the ultraviolet rays for irradiating the above ultraviolet-curable acrylic adhesive composition is preferably in the range of 200 nm to 500 nm, more preferably in the range of 300 nm to 450 nm. When the peak wavelength of the ultraviolet rays is greater than 500 nm, sometimes the photoinitiator does not decompose and does not initiate the polymerization reaction. In addition, when the peak wavelength of the ultraviolet rays is less than 200 nm, sometimes the polymer chain is cut off and the adhesive characteristics are reduced.

[0123] From the viewpoint of ensuring the ultraviolet absorption function, the thickness of the adhesive layer of the present invention is preferably 50 μm or more, more preferably 100 μm or more, and further preferably 150 μm or more. There is no particular limitation on the upper limit value of the thickness of the adhesive layer, and it is preferably 10 mm or less. When the thickness of the adhesive layer is greater than 10 mm, the transmission of ultraviolet rays becomes difficult, the polymerization of the monomer component takes time, and sometimes the productivity is poor, so it is not preferred.

[0124] There is no particular limitation on the gel fraction of the adhesive layer of the present invention, and it is preferably 50% or more, more preferably 75% or more, and further preferably 85% or more. When the gel fraction of the adhesive layer is small, the cohesive force is poor. When the gel fraction of the adhesive layer is too large, sometimes the adhesive force is poor.

[0125] The transmission b* value of the adhesive layer, the transmittance at a wavelength of 380 nm, and the transmittance at a wavelength of 400 nm are as described above.

[0126] The adhesive layer of the present invention is used in an image display device. More specifically, it is located between the protective glass or protective plastic and the polarizing film in the image display device. By the adhesive layer of the present invention being located at this position, the ultraviolet absorption function can be fully exerted.

[0127] 3. Polarizing film with an adhesive layer

[0128] The polarizing film with an adhesive layer of the present invention is characterized in that it has a polarizing film and has the above ultraviolet-curable acrylic adhesive layer on at least one surface of the polarizing film.

[0129] The method for forming the ultraviolet-curable acrylic adhesive layer is as described above. The adhesive layer can be formed by directly coating the ultraviolet-curable acrylic adhesive composition on the polarizing film. In addition, the adhesive layer can also be formed on a release film or the like, and then the adhesive layer is transferred onto the polarizing film, whereby the adhesive layer is formed on the polarizing film.

[0130] As the polarizing film, a polarizing film having a transparent protective film on at least one surface of the polarizer is preferred.

[0131] There is no particular limitation on the polarizer, and various polarizers can be used. As the polarizer, for example, a polarizer obtained by subjecting a hydrophilic polymer film such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, or a partially saponified ethylene-vinyl acetate copolymer film to uniaxial stretching after adsorbing a dichroic substance such as iodine or a dichroic dye, a polyolefin-oriented film such as a dehydrated product of polyvinyl alcohol or a dehydrochlorinated product of polyvinyl chloride, etc. Among them, a polarizer containing a polyvinyl alcohol-based film and a dichroic substance such as iodine is preferred. The thickness of these polarizers is not particularly limited, and is usually about 5 μm to about 80 μm.

[0132] A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and performing uniaxial stretching can be produced, for example, by immersing the polyvinyl alcohol in an aqueous solution of iodine for dyeing and stretching it to 3 to 7 times its original length. It can also be immersed in an aqueous solution of potassium iodide or the like that may contain boric acid, zinc sulfate, zinc chloride, etc. as needed. Further, the polyvinyl alcohol-based film can be immersed in water for washing before dyeing as needed. By washing the polyvinyl alcohol-based film, stains and anti-blocking agents on the surface of the polyvinyl alcohol-based film can be removed. In addition, it has the effect of preventing unevenness such as uneven dyeing by swelling the polyvinyl alcohol-based film. The stretching can be performed after dyeing with iodine, or can be performed simultaneously with dyeing, and can also be dyed with iodine after stretching. The stretching can be performed in an aqueous solution or a water bath of boric acid, potassium iodide, etc.

[0133] In addition, in the present invention, a thin polarizer having a thickness of 10 μm or less can also be used. From the viewpoint of thinning, the thickness is preferably 1 μm to 7 μm. Such a thin polarizer has less thickness unevenness, excellent visual recognition, and little dimensional change, and thus has excellent durability. In addition, it is preferred from the aspect of achieving thinning in terms of the thickness as a polarizing film.

[0134] As the thin polarizer, typically, a thin polarizing film described in Japanese Patent Laid-Open No. 51-069644, Japanese Patent Laid-Open No. 2000-338329, International Publication No. 2010 / 100917 pamphlet, or Japanese Patent No. 4751481, Japanese Patent Laid-Open No. 2012-073563 can be cited. These thin polarizing films can be obtained by a manufacturing method including a step of stretching a polyvinyl alcohol-based resin (hereinafter also referred to as a PVA-based resin) layer and a stretching resin substrate in a laminated state and a step of performing dyeing. By using this manufacturing method, even if the PVA-based resin layer is thin, it can be stretched without problems such as breakage due to stretching by being supported by the stretching resin substrate.

[0135] As for the above-mentioned thin polarizing film, from the aspect that it can be stretched at a high magnification even in the manufacturing method including the stretching process and the dyeing process in the state of being included in the laminate to improve the polarization performance, it is preferably a polarizing film obtained by a manufacturing method including a stretching process in an aqueous boric acid solution as described in the pamphlet of International Publication No. 2010 / 100917, or the specification of Japanese Patent No. 4751481, or Japanese Patent Laid-Open No. 2012-073563. In particular, it is preferably a polarizing film obtained by a manufacturing method including a process of stretching assistively in air before stretching in an aqueous boric acid solution as described in the specification of Japanese Patent No. 4751481 and Japanese Patent Laid-Open No. 2012-073563.

[0136] As for the material for forming the transparent protective film provided on one or both sides of the polarizer, materials excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, etc. are preferred. For example, polyester polymers such as polyethylene terephthalate or polyethylene naphthalate, cellulose polymers such as diacetyl cellulose or triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene polymers such as polystyrene or acrylonitrile-styrene copolymer (AS resin), polycarbonate polymers, etc. can be cited. In addition, polyolefin polymers such as polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, ethylene-propylene copolymer, etc., vinyl chloride polymers, amide polymers such as nylon or aromatic polyamide, imide polymers, sulfone polymers, polyethersulfone polymers, polyetheretherketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers, vinyl butyral polymers, aromatic ester polymers, polyoxymethylene polymers, epoxy polymers, or blends of the above polymers can be cited as examples of the polymers for forming the above transparent protective film. The transparent protective film can also be formed in the form of a cured layer of a thermosetting type or ultraviolet curable type resin such as acrylic, polyurethane, acrylic polyurethane, epoxy, polysiloxane, etc.

[0137] The thickness of the protective film can be appropriately determined. Usually, from the aspects of workability such as strength and processability, and thin film properties, it is about 1 μm to about 500 μm.

[0138] The polarizer and the protective film are usually adhered via an aqueous adhesive or the like. As the aqueous adhesive, isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl type latexes, aqueous polyurethanes, aqueous polyesters, etc. can be cited. In addition to the above, as the adhesive for the polarizer and the transparent protective film, ultraviolet curable adhesives, electron beam curable adhesives, etc. can be cited. The electron beam curable adhesive for the polarizing film shows appropriate adhesiveness to the above various transparent protective films. In addition, a metal compound filler can be contained in the adhesive used in the present invention.

[0139] A hard coating treatment, an antireflection treatment, or a treatment for preventing adhesion, diffusion, or antiglare can be performed on the surface of the transparent protective film that is not adhered to the polarizer.

[0140] In addition, when the adhesive layer of the polarizing film with an adhesive layer of the present invention is exposed, the adhesive layer can be protected with a release film (separator) until actual use. Examples of the release film include the above-mentioned release film. When the release film is used as a base material in the production of the above-mentioned adhesive layer, by laminating the adhesive layer on the release film with the polarizing film, the release film can be used as the release film for the adhesive layer of the polarizing film with an adhesive layer, thus simplifying the process.

[0141] 4. Method for manufacturing the adhesive layer

[0142] The present invention relates to a method for manufacturing an ultraviolet-curable acrylic adhesive layer, which is a method for manufacturing an adhesive layer formed from an ultraviolet-curable acrylic adhesive composition containing a photopolymerization initiator (B).

[0143] It is characterized in that

[0144] The manufacturing method includes: a step of irradiating ultraviolet rays to a composition containing a monomer component containing (meth)acrylic acid alkyl ester and the photopolymerization initiator (B) to form a partial polymer of the monomer component;

[0145] a step of adding an ultraviolet absorber and a photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more to the partial polymer of the monomer component to produce an ultraviolet-curable acrylic adhesive composition; and

[0146] a step of coating the ultraviolet-curable acrylic adhesive composition on at least one side of a substrate and irradiating the ultraviolet-curable acrylic adhesive composition with ultraviolet rays.

[0147] Each component constituting the ultraviolet-curable acrylic adhesive composition is as described above.

[0148] When forming an adhesive layer from an ultraviolet-curable acrylic adhesive composition containing a photopolymerization initiator (B), first, ultraviolet rays are irradiated to a composition containing a monomer component containing (meth)acrylic acid alkyl ester and the photopolymerization initiator (B) (sometimes also referred to as "pre-addition of the polymerization initiator") 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 further preferably about 5% to about 15%. The irradiation conditions of the ultraviolet rays are as described above.

[0149] Next, an ultraviolet absorber and a photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more (sometimes also referred to as a "post-added polymerization initiator") are added to a partial polymer of the monomer component to produce an ultraviolet curable acrylic adhesive composition. The ultraviolet absorber, the photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more, and their addition amounts are as described above.

[0150] The ultraviolet curable acrylic adhesive composition obtained in this way is applied to at least one side of a substrate, and the ultraviolet curable acrylic adhesive composition is irradiated with ultraviolet rays, whereby an ultraviolet curable acrylic adhesive layer can be manufactured. The irradiation conditions of the ultraviolet rays are as described above.

[0151] The substrate is not particularly limited, and various substrates such as a release film and a transparent resin film substrate can be cited. In addition, the polarizing film described later can also be suitably used as the substrate.

[0152] As the constituent material of the release film, for example, resin films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester film; porous materials such as paper, cloth, and non-woven fabric; appropriate thin paper-like materials (thin leaf bodies) such as meshes, foamed sheets, metal foils, and their laminates, etc. are cited. From the viewpoint of excellent surface smoothness, a resin film is preferably used.

[0153] As the resin film, for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, etc. are cited.

[0154] The thickness of the release film is usually about 5 μm to about 200 μm, preferably about 5 μm to about 100 μm. The release film can be subjected to release and antifouling treatment using silicone-based, fluorine-based, long-chain alkyl-based, or fatty acid amide-based release agents, silica powder, etc. as needed, or antistatic treatment such as coating type, kneading type, or vapor deposition type. In particular, by appropriately performing release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the release film, the peelability from the adhesive layer can be further improved.

[0155] As for the transparent resin film substrate, there is no particular limitation, and various resin films with transparency are used. The resin film is formed of a single layer. As its material, for example, 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, polyphenylene sulfide resins, etc. can be cited. Among these, polyester resins, polyimide resins, and polyethersulfone resins are particularly preferred.

[0156] The thickness of the film substrate is preferably 15 μm to 200 μm, more preferably 25 μm to 188 μm.

[0157] As a method for coating the above ultraviolet-curable acrylic adhesive composition on the above substrate, known and appropriate methods such as a roll coater, a bar coater, and a slot die coater can be used, and there is no particular limitation.

[0158] The reaction is inhibited by oxygen in the air. Therefore, in order to block oxygen, it is preferable to form a release film or the like on the coating layer of the acrylic adhesive composition or to carry out the photopolymerization reaction in a nitrogen atmosphere. It should be noted that the above release film can be cited as the release film.

[0159] As described above, in the case where the adhesive layer is formed of the ultraviolet-curable acrylic adhesive composition containing the photopolymerization initiator (B), it is preferable to first add the photopolymerization initiator (B) to form a partial polymer of the monomer component, and then add an ultraviolet absorber and a photopolymerization initiator (A) having an absorption band at 400 nm or more to the partial polymer, thereby preparing the ultraviolet-curable acrylic adhesive composition. Thus, by carrying out the polymerization in two stages, the polymerization rate of the monomer component can be increased, and the ultraviolet absorption function of the finally prepared adhesive layer can be improved.

[0160] 5. Image display device

[0161] 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

[0162] The image display device has the adhesive layer between the protective glass or the protective plastic and the polarizing film.

[0163] The image display device has at least one polarizing film and at least one protective glass or protective plastic, and the specific configuration is as described above. In addition, as the image display device, a liquid crystal display device, an organic EL (electroluminescence) display device, a PDP (plasma display panel), an electronic paper, etc. can be cited. Among these, a liquid crystal display device, an organic EL (electroluminescence) display device, etc. having the above configuration are preferred.

[0164] Example

[0165] Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. It should be noted that the parts and % in each example are based on weight. The evaluation items in the examples and the like were measured in the following manner.

[0166] Production Example 1 (Production of acrylic adhesive composition (a-1))

[0167] In a monomer mixture composed of 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), 0.035 part by weight of 1-hydroxycyclohexyl phenyl ketone (trade name: Irgacure 184, manufactured by BASF) and 0.035 part by weight of 2,2-dimethoxy-1,2-diphenylethane-1-one (trade name: Irgacure 651, manufactured by BASF) as a photopolymerization initiator (added the photopolymerization initiator first) were added, and then ultraviolet rays were irradiated until the viscosity (measurement conditions: BH viscometer, No. 5 rotor, 10 rpm, measurement temperature 30 °C) was about 20 Pa·s, thereby obtaining a prepolymer composition (polymerization rate: 8%) obtained by polymerizing a part of the above monomer components. Subsequently, 0.15 part by weight of hexanediol diacrylate (HDDA) and 0.3 part by weight of a silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to this prepolymer composition, mixed, and irradiated with ultraviolet rays, whereby an acrylic adhesive composition (a-1) was obtained.

[0168] Production Example 2 (Production of acrylic adhesive composition (a-2))

[0169] 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 parts by weight of 2,2-dimethoxy-1,2-diphenylethane-1-one (trade name: Irgacure 651, manufactured by BASF Japan Ltd.) and 0.09 parts by weight of 1-hydroxycyclohexyl phenyl ketone (trade name: Irgacure 184, manufactured by BASF Japan Ltd.) as a photopolymerization initiator were put into a four-necked flask and partially photopolymerized by exposure to ultraviolet rays in a nitrogen atmosphere, whereby a partial polymer (monomer slurry) with a polymerization rate of 10% was obtained. 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, mixed, and irradiated with ultraviolet rays, whereby an acrylic adhesive composition (a-2) was obtained.

[0170] Example 1

[0171] 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 Ltd.) dissolved in butyl acrylate so that the solid content was 15% and 0.2 parts of bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (trade name: Irgacure 819, manufactured by BASF Japan Ltd.) as a post-added polymerization initiator were added to the acrylic adhesive composition (a-1) and stirred to obtain an ultraviolet curable acrylic adhesive composition.

[0172] The above ultraviolet curable acrylic adhesive composition was coated on the peeled surface of a release film 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 laminated on the surface of the coating layer. Then, under the conditions of illuminance: 6.5 mW / cm 2 , light quantity: 1500 mJ / cm 2 , ultraviolet irradiation was performed to photocure the coating layer, thereby forming an adhesive sheet having release films on both sides of the adhesive layer.

[0173] Examples 2 to 16, Comparative Examples 1 to 6

[0174] Except for setting the type of the acrylic adhesive composition used, the ultraviolet absorber, the type and addition amount of the post-added photoinitiator, and the thickness after the formation of the adhesive layer as described in Table 1, an ultraviolet curable acrylic adhesive composition was prepared in the same manner as in Example 1 to form an adhesive sheet. However, for Comparative Examples 5 and 6, as shown in Table 2, the solubility of the acrylic adhesive composition and the ultraviolet absorber was poor, so although an ultraviolet curable acrylic adhesive composition was prepared, the formation of the adhesive sheet was not carried out.

[0175]

[0176] In Table 1,

[0177] a-1 represents the acrylic adhesive composition (a-1) obtained in Production Example 1,

[0178] a-2 represents the acrylic adhesive composition (a-2) obtained in Production Example 2,

[0179] Tinosorb S represents 2,4-bis[{4-(4-ethylhexyloxy)-4-hydroxy}phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (manufactured by BASF),

[0180] Tinuvin928 represents 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (manufactured by BASF),

[0181] LA-F70 represents 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine (manufactured by ADEKA),

[0182] KEMISORB279 represents 2,2'-methylenebis[6-(benzotriazol-2-yl)-4-tert-octylphenol] (manufactured by Chemipro Kasei Co., Ltd.),

[0183] Irgacure819: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name, manufactured by BASF Japan), having an absorption band in the wavelength range of 200 nm to 450 nm,

[0184] Irgacure651: 2,2-dimethoxy-1,2-diphenylethane-1-one (trade name, manufactured by BASF Japan), having an absorption band in the wavelength range of 200 nm to 380 nm,

[0185] Irgacure 184: 1-hydroxycyclohexyl phenyl ketone (trade name, manufactured by BASF Japan Ltd.), which has an absorption band in the wavelength range of 200 nm to 370 nm.

[0186] The following evaluations were performed on the obtained adhesive sheets.

[0187] <Solubility>

[0188] Each ultraviolet absorber used in the examples and comparative examples shown in Table 1 in the amounts shown in Table 1 based on 100 parts by weight of the acrylic adhesive composition was added, and the solubility was visually observed and evaluated according to the following evaluation criteria.

[0189] ○: The ultraviolet absorber was dissolved in the acrylic adhesive composition without any undissolved residue.

[0190] ×: An undissolved residue was produced in the acrylic adhesive composition by the ultraviolet absorber.

[0191] <Polymerization rate>

[0192] The release films on both sides of the adhesive sheets obtained in the examples and comparative examples were peeled off, and only the adhesive layer was placed in an aluminum dish after measuring the weight. The weight of (aluminum dish + adhesive layer) was measured to obtain the weight of the adhesive layer before drying. After drying at 130 °C for 2 hours, it was cooled at room temperature for about 20 minutes, and then the weight of (aluminum dish + adhesive) was measured again to obtain the weight of the adhesive layer after drying. The polymerization rate was calculated according to the following calculation formula.

[0193]

[0194] <Gel fraction>

[0195] Approximately 0.1 g of the adhesive layer was selected from the adhesive sheets obtained in the examples and comparative examples, wrapped with a porous polytetrafluoroethylene sheet (trade name: NTF1122, manufactured by Nitto Denko Corporation) having an average pore diameter of 0.2 μm, and then tied with a kite string. The weight (Z g) at this time was measured and used as the weight before impregnation. It should be noted that this weight before impregnation is the total weight of the adhesive layer (the above-selected adhesive layer), the polytetrafluoroethylene sheet, and the kite string. In addition, the total weight (Y g) of the polytetrafluoroethylene sheet and the kite string was also measured. Then, the adhesive layer wrapped with the polytetrafluoroethylene sheet and tied with the kite string (referred to as "sample") was placed in a 50 mL container filled with ethyl acetate and allowed to stand at 23 °C for 7 days. Then, the sample (after ethyl acetate treatment) was taken out of the container, transferred to an aluminum cup, dried in a dryer at 130 °C for 2 hours to remove ethyl acetate, and then the weight (X g) was measured and used as the weight after impregnation. The gel fraction was calculated by the following formula.

[0196] Gel fraction (wt%) = (X - Y) / (Z - Y) × 100

[0197] <Measurement of transmittance and b* value>

[0198] The release films on both sides of the adhesive sheets obtained in the examples and comparative examples were peeled off, the adhesive layer was mounted on a measurement jig, and measurement was performed using a spectrophotometer (product name: U4100, manufactured by Hitachi High-Technologies Corporation).

[0199] <Optical reliability of the adhesive layer monomer>

[0200] The release films on both sides of the adhesive sheets obtained in the examples and comparative examples were peeled off, and glass (product name: S200200, thickness: 1.3 mm, size: 45 mm × 50 mm, manufactured by Matsunami Glass Industry Co., Ltd.) was bonded to both sides of the adhesive layer, and autoclave treatment (air pressure: 0.5 MPa, temperature: 50 °C) was performed for 15 minutes. The transmittance and hue after being respectively put into the following various reliability conditions 1 to 5 were measured using U4100 (product name) manufactured by Hitachi High-Technologies Corporation, and the change amount of the transmittance compared with the initial value was obtained. Evaluation was performed according to the following evaluation criteria.

[0201] (Various reliability conditions)

[0202] (Condition 1) 85 °C × 500 hours

[0203] (Condition 2) -40 °C × 500 hours

[0204] (Condition 3) 60 °C, 95% × 500 hours

[0205] (Condition 4) Thermal shock (HS) (-40 °C to 85 °C) × 300 cycles

[0206] (Condition 5) Under UV irradiation × 100 hours, illuminance: 500 W / cm 2 (300 nm to 700 nm), ambient temperature: 60 °C to 65 °C, ambient humidity: 50%

[0207] (Evaluation criteria)

[0208] ◎: The change amount of the transmittance is 0.2% or less.

[0209] ○: The change amount of the transmittance is greater than 0.2% and 0.7% or less.

[0210] △: The change amount of the transmittance is greater than 0.7% and 1.0% or less.

[0211] ×: The change amount of the transmittance is greater than 1.0%.

[0212] <Visual recognition>

[0213] A polarizing film was prepared in which a TAC film (25 μm) with a hard coat treatment was provided on one surface of a polarizer having a thickness of 12 μm, and an acrylic film (20 μm) was provided on the other surface of the polarizer. The release films on both sides of the adhesive sheets obtained in the examples and comparative examples were peeled off, an adhesive layer was bonded to each protective film of the polarizing film, and further glass (trade name: S200200, thickness: 1.3 mm, size: 45 mm × 50 mm, manufactured by Matsunami Glass Industry Co., Ltd.) was bonded to the adhesive layers on both sides, thereby preparing a measurement sample. The obtained measurement sample was subjected to an autoclave treatment for 15 minutes (air pressure: 0.5 MPa, temperature: 50 °C). Measurement was performed using an ultraviolet-visible-near-infrared spectrophotometer (product name: V7100, manufactured by JASCO Corporation), and color tone measurement was performed, and evaluation was carried out according to the following evaluation criteria.

[0214] 〇: The b value is 1.4 or more and 3.4 or less

[0215] △: The b value is greater than 3.4 and 3.9 or less

[0216] ×: The b value is greater than 3.9

[0217] <Durability>

[0218] The release films on both sides of the adhesive sheets obtained in the examples and comparative examples were peeled off, and glass (trade name: S200200, thickness: 1.3 mm, size: 45 mm × 50 mm, manufactured by Matsunami Glass Industry Co., Ltd.) was bonded to both sides of the adhesive layer, thereby preparing a measurement sample. The obtained measurement sample was subjected to an autoclave treatment for 15 minutes (air pressure: 0.5 MPa, temperature: 50 °C). After being put into various reliability conditions shown in Table 1 (Condition 1: 85 °C × 500 hours, Condition 2: -40 °C × 500 hours, Condition 3: 60 °C 95% × 500 hours, Condition 4: cycles, Condition 5: Under UV irradiation × 100 hours), the evaluation samples were measured using a magnifying glass or an electron microscope. Evaluation was carried out according to the following evaluation criteria.

[0219] 〇: There is no peeling or foaming starting from the end.

[0220] ×: Peeling or foaming occurs.

[0221] <UV resistance (protection function of polarizing film)>

[0222] A polarizing film was prepared in which one surface of a polarizer with a thickness of 12 μm was protected by a TAC film (25 μm) with a hard coat treatment, and the other surface of the polarizer was protected by an acrylic film (20 μm). The release films on both sides of the adhesive sheets obtained in the examples and comparative examples were peeled off, and the adhesive layers were bonded to the respective protective films of the polarizing film. Further, glass (trade name: S200200, thickness: 1.3 mm, size: 45 mm × 50 mm, manufactured by Matsunami Glass Industry Co., Ltd.) was bonded to the adhesive layers on both sides to prepare a measurement sample. The obtained measurement sample was subjected to an autoclave treatment for 15 minutes (air pressure: 0.5 MPa, temperature: 50 °C). Then, it was put into UV irradiation conditions of illuminance: 500 W / cm 2 (300 nm to 700 nm), ambient temperature: 60 °C to 65 °C, ambient humidity: 50%, and measured with a UV-visible near-infrared spectrophotometer (product name: V7100, manufactured by JASCO Corporation) to obtain the change amount of transmittance compared to the initial value. Evaluation was carried out according to the following evaluation criteria.

[0223] ◎: The change amount of transmittance is 1.0% or less.

[0224] ○: The change amount of transmittance is greater than 1.0% and 2.0% or less.

[0225] △: The change amount of transmittance is greater than 2.0% and 3.0% or less.

[0226] ×: The change amount of transmittance is greater than 3.0%.

[0227]

[0228] Reference numeral

[0229] 1 Protective glass or protective plastic

[0230] 2a - 2c Adhesive layer

[0231] 3a, 3b Protective film

[0232] 4 Polarizer

[0233] 5 Polarizing film

[0234] 6 Liquid crystal display device (LCD) or organic EL display device (OLED)

[0235] 7 Sensor layer

Claims

1. An ultraviolet-curable acrylic adhesive composition for forming an adhesive layer between a protective glass or protective plastic and a polarizing film in an image display device. Characterized in that, the adhesive composition contains: a monomer component containing an alkyl (meth)acrylate and a hydroxyl group-containing monomer as a monofunctional monomer component which is a comonomer other than the 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 400 nm or more. Relative to the total amount of the monofunctional monomer components in the monomer component, the alkyl (meth)acrylate is 40% by weight or more and the hydroxyl group-containing monomer is 30% by weight or less. The addition amount of the photopolymerization initiator (A) is less than the addition amount of the ultraviolet absorber. The transmittance of the adhesive layer formed from the adhesive composition at a wavelength of 380 nm is 40% or less, and the transmittance of the adhesive layer formed from the adhesive composition at a wavelength of 400 nm is 30% or more. Relative to 100 parts by weight of the monofunctional monomer components forming the (meth)acrylic polymer, the content of the ultraviolet absorber is 0.5 part by weight to 3 parts by weight, and relative to 100 parts by weight of the monofunctional monomer components forming the (meth)acrylic polymer, the addition amount of the photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more is 0.005 part by weight to 0.2 part by weight.

2. The ultraviolet-curable acrylic adhesive composition according to claim 1. Characterized in that, the transmittance b* value of the adhesive layer is 3.0 or less.

3. The ultraviolet-curable acrylic adhesive composition according to claim 1. Characterized in that, the ultraviolet absorber is at least one ultraviolet absorber selected from the group consisting of triazine-based ultraviolet absorbers having 2 or less hydroxyl groups in one molecule and benzotriazole-based ultraviolet absorbers having 1 benzotriazole skeleton in one molecule.

4. The ultraviolet-curable acrylic adhesive composition according to any one of claims 1 to 3. Characterized in that, the ultraviolet-curable acrylic adhesive composition further contains a photopolymerization initiator (B) having an absorption band at a wavelength less than 400 nm.

5. An ultraviolet-curable acrylic adhesive layer which is an adhesive layer between a protective glass or protective plastic and a polarizing film in an image display device. Characterized in that, the ultraviolet-curable acrylic adhesive layer is formed by irradiating ultraviolet rays to the ultraviolet-curable acrylic adhesive composition according to any one of claims 1 to 4 to cause photopolymerization of the monomer components in the ultraviolet-curable acrylic adhesive composition.

6. 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 according to claim 5 on at least one surface of the polarizing film.

7. A method for manufacturing an ultraviolet-curable acrylic adhesive layer, which is a method for manufacturing an adhesive layer formed from the ultraviolet-curable acrylic adhesive composition according to claim 4, characterized in that, the manufacturing method includes: a step of irradiating ultraviolet rays to a composition containing a monomer component containing (meth)acrylic acid alkyl ester and the photopolymerization initiator (B) 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 400 nm or more in wavelength to the partial polymer of the monomer component to produce an ultraviolet-curable acrylic adhesive composition; and a step of applying the ultraviolet-curable acrylic adhesive composition to at least one side of a substrate and irradiating ultraviolet rays to the ultraviolet-curable acrylic adhesive composition.

8. An image display device having at least a protective glass or a protective plastic and a polarizing film, characterized in that, the image display device has the ultraviolet-curable acrylic adhesive layer according to claim 5 between the protective glass or the protective plastic and the polarizing film.

Images