JP6592254B2 - UV-curable acrylic pressure-sensitive adhesive composition, UV-curable acrylic pressure-sensitive adhesive layer, polarizing film with pressure-sensitive adhesive layer, method for producing UV-curable acrylic pressure-sensitive adhesive layer, and image display device - Google Patents

Description

  The present invention relates to an ultraviolet curable acrylic pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer located between a cover glass or a cover plastic and a polarizing film in an image display device. The present invention also includes an ultraviolet curable acrylic pressure-sensitive adhesive layer formed from the ultraviolet curable acrylic pressure-sensitive adhesive composition, a polarizing film with a pressure-sensitive adhesive layer having the ultraviolet curable acrylic pressure-sensitive adhesive layer, and the ultraviolet curable type. The present invention relates to a method for producing an 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.

  In liquid crystal display devices and organic EL display devices, for example, in liquid crystal display devices, it is indispensable to dispose polarizing elements on both sides of the liquid crystal cell, and generally a polarizing film is attached. Has been. In addition to polarizing films, various optical elements have been used for display panels such as liquid crystal panels and organic EL panels in order to improve the display quality of displays.

  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.

  In recent years, with the trend of reducing the weight and thickness of image display devices, it has been required to reduce the thickness of each member used in the image display device, and also to reduce the thickness of the protective film of the polarizing film. When the thickness of the protective film is reduced, the ultraviolet light incident on the image display device cannot be sufficiently cut, and not only the polarizer but also various optical members such as liquid crystal panels and organic EL elements used in the image display device. There was a problem that the deterioration due to ultraviolet rays was accelerated.

  In order to solve such a problem, for example, a double-sided pressure-sensitive adhesive sheet for integrating two members disposed between the surface protection panel in the image display device and the viewing side of the liquid crystal module, Transparent double-sided pressure-sensitive adhesive for image display devices, having at least one ultraviolet absorbing layer, having a light transmittance of 380 nm or less and a visible light transmittance of 80% or more on a longer wavelength side than the wavelength of 430 nm There are known a sheet (for example, see Patent Document 1) and a pressure-sensitive adhesive sheet containing an acrylic polymer and a triazine ultraviolet absorber (for example, see Patent Document 2). Further, it is known that an ultraviolet absorbing ability can be imparted to the pressure-sensitive adhesive layer in a pressure-sensitive adhesive optical film in which a pressure-sensitive adhesive layer is provided on one or both sides of the optical film (see, for example, Patent Document 3).

JP 2012-211305 A JP 2013-75978 A Japanese Patent No. 4208187

  In the pressure-sensitive adhesive sheets of Patent Documents 1 and 2, since the thickness of the pressure-sensitive adhesive layer containing the ultraviolet absorber is thin, the ultraviolet absorption function is not sufficient. Moreover, since the thickness of the pressure-sensitive adhesive layer is thin, there is a case where problems such as generation of bubbles occur when unevenness (step difference) absorbency is required. In these patent documents, polymerization by ultraviolet irradiation is not performed in the formation of the pressure-sensitive adhesive layer containing the ultraviolet absorber, and naturally, a photopolymerization initiator having an absorption band at a wavelength of 400 nm or more has been studied. There is nothing.

  Patent Document 3 does not specifically discuss the formation of a pressure-sensitive adhesive layer having an ultraviolet absorption function using a polymerization method by ultraviolet irradiation, and photopolymerization having an absorption band at a wavelength of 400 nm or more. Initiators have not been fully studied.

In addition to Patent Documents 1 to 3, various transparent adhesives having an ultraviolet absorbing function are known. Currently known transparent adhesives having an ultraviolet absorbing function are obtained by subjecting a base polymer of an adhesive to solution polymerization. Most of the products manufactured by In such a production method, it is difficult to produce a thick product having a thickness of 150 μm or more, and there is a limit to the thickness of the pressure-sensitive adhesive layer that can be produced. In the case of using the polymerization method by ultraviolet irradiation, it is known that can form a thick thick adhesive layer, the adhesive layer having an ultraviolet absorbing function, a method that forms form after polymerization method by ultraviolet irradiation The current situation is not known.

  Then, an object of this invention is to provide the ultraviolet curing acrylic adhesive composition which can form the adhesive layer which has an ultraviolet-ray absorption function with the polymerization method by ultraviolet irradiation. Further, the present invention provides an ultraviolet curable acrylic pressure-sensitive adhesive layer formed from the ultraviolet curable acrylic pressure-sensitive adhesive composition, a polarizing film with an adhesive layer having the ultraviolet curable acrylic pressure-sensitive adhesive layer, and the ultraviolet curable It is another object of the present invention to provide a method for producing an acrylic pressure-sensitive adhesive layer and an image display device.

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

That is, the present invention is an ultraviolet curable acrylic pressure-sensitive adhesive composition for forming a pressure-sensitive adhesive layer located between a cover glass or a cover plastic and a polarizing film in an image display device,
The pressure-sensitive adhesive composition includes 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. ,
The UV-curable acrylic pressure-sensitive adhesive composition, wherein the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition has a transmittance of 40% or less at a wavelength of 380 nm and a transmittance of 30% or more at a wavelength of 400 nm. About.

  The permeation b * value of the pressure-sensitive adhesive layer is preferably 3.0 or less.

  The ultraviolet absorber is at least selected from the group consisting of a triazine-based ultraviolet absorber having 2 or less hydroxyl groups in one molecule and a benzotriazole-based ultraviolet absorber having one benzotriazole skeleton in one molecule. One kind of ultraviolet absorber is preferable.

  It is preferable that the addition amount of the photopolymerization initiator (A) is smaller than the addition amount of the ultraviolet absorber.

  The ultraviolet curable acrylic pressure-sensitive adhesive composition of the present invention preferably further contains a photopolymerization initiator (B) having an absorption band at a wavelength of less than 400 nm.

The present invention is an adhesive layer positioned between a cover glass or a cover plastic and a polarizing film in an image display device,
The ultraviolet curable acrylic pressure-sensitive adhesive is formed by irradiating the ultraviolet curable acrylic pressure-sensitive adhesive composition with ultraviolet rays to photopolymerize a monomer component in the ultraviolet curable acrylic pressure-sensitive adhesive composition. The agent layer.

  The present invention relates to a polarizing film and a polarizing film with a pressure-sensitive adhesive layer comprising the ultraviolet curable acrylic pressure-sensitive adhesive layer on at least one surface of the polarizing film.

Further, the present invention 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),
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 400 nm or more to the partially polymerized monomer component to prepare an ultraviolet curable acrylic pressure-sensitive adhesive composition;
An ultraviolet curable acrylic pressure-sensitive adhesive comprising 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 rays. The present invention relates to a method for producing an agent layer.

Furthermore, the present invention is an image display device having at least a cover glass or a cover plastic and a polarizing film,
The present invention relates to an image display device comprising the ultraviolet curable acrylic pressure-sensitive adhesive layer between the cover glass or cover plastic and a polarizing film.

  The ultraviolet curable acrylic pressure-sensitive adhesive composition of the present invention can form a pressure-sensitive adhesive layer having an ultraviolet absorption function by a polymerization method by ultraviolet irradiation, so that a thick pressure-sensitive adhesive layer of 150 μm or more can be formed. A wide-thickness pressure-sensitive adhesive layer can be formed. Since the pressure-sensitive adhesive layer of the present invention has an excellent ultraviolet absorption function, the deterioration of optical members such as liquid crystal panels, organic EL elements, polarizers and the like is suppressed by using the pressure-sensitive adhesive layer in an image display device. be able to.

It is sectional drawing which shows typically one Embodiment of the image display apparatus of this invention. It is sectional drawing which shows typically one Embodiment of the image display apparatus of this invention. It is sectional drawing which shows typically one Embodiment of the image display apparatus of this invention.

1. Ultraviolet-curing acrylic pressure-sensitive adhesive composition The ultraviolet-curable acrylic pressure-sensitive adhesive composition of the present invention is an ultraviolet ray for forming a pressure-sensitive adhesive layer located between a cover glass or a cover plastic and a polarizing film in an image display device. A curable acrylic pressure-sensitive adhesive composition,
The pressure-sensitive adhesive composition includes 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. ,
The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition has a transmittance at a wavelength of 380 nm of 40% or less and a transmittance at a wavelength of 400 nm of 30% or more.

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

As an example of the configuration of the image display device, for example, as shown in FIGS.
Cover glass or cover plastic 1 / adhesive layer 2a / polarizing film 5 / liquid crystal display (LCD) or organic EL display (OLED) 6;
Cover glass or cover plastic 1 / adhesive layer 2b / sensor layer 7 / adhesive layer 2a / polarizing film 5 / liquid crystal display (LCD) or organic EL display (OLED) 6;
Cover glass or cover 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;
As described above, an image display device in which the respective layers are stacked in this order can be given. In addition to these layers, a retardation film or the like can be appropriately added. Specifically, the adhesive film is adhered between the polarizing film 5 and a liquid crystal display device (LCD) or an organic EL display device (OLED) 6. It can laminate | stack through an agent layer. Moreover, in lamination | stacking of each layer, an adhesive layer and / or an adhesive layer can be used suitably. The polarizing film 5 in FIGS. 1 to 3 has a configuration in which the polarizer 4 is sandwiched between two protective films 3a and 3b, but one side of the polarizer 4 is protected by a protective film. A polarizing film may be sufficient.

  The pressure-sensitive adhesive layer comprising the ultraviolet curable acrylic pressure-sensitive adhesive composition of the present invention is closer to the viewing side than the cover glass or cover plastic 1 in the image display device and the liquid crystal display device (LCD) or organic EL display device (OLED) 6. Although it is an adhesive layer located between the polarizing film 5 which exists and may be any place of the adhesive layers 2a-2c in FIGS. 1-3, the adhesive layer which touches the polarizing film 5 (in the figure) It is more preferable to use the pressure-sensitive adhesive layer of the present invention in 2a) from the viewpoint of ultraviolet absorbing ability. By disposing the adhesive layer made of the ultraviolet curable acrylic adhesive composition of the present invention at the position, the polarizing film in the image display device is protected from ultraviolet light incident from the viewing side in the image display device. Is preferable.

  The ultraviolet curable acrylic pressure-sensitive 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 having an absorption band at a wavelength of 400 nm or more. It contains an initiator (A).

  Examples of the alkyl (meth) acrylate include those having a linear or branched alkyl group having 1 to 24 carbon atoms at the ester terminal. Alkyl (meth) acrylate can be used individually by 1 type or in combination of 2 or more types. Alkyl (meth) acrylate refers to alkyl acrylate and / or alkyl methacrylate, and (meth) in the present invention has the same meaning.

  As said alkyl (meth) acrylate, the alkyl (meth) acrylate which has the alkyl group which has a C4-C9 branch at the ester terminal can be illustrated, for example. The alkyl (meth) acrylate is preferable in terms of easily balancing the adhesive properties. Specifically, n-butyl (meth) acrylate, s-butyl (meth) acrylate, t-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 are used, and these are used alone or in combination of two or more. be able to.

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

  The monomer component that forms the (meth) acrylic polymer may contain a copolymerizable monomer other than the alkyl (meth) acrylate as a monofunctional monomer component. A copolymerization monomer can be used as the remainder of the said alkyl (meth) acrylate in a monomer component.

  As the copolymerization monomer, for example, a cyclic nitrogen-containing monomer can be included. As said cyclic nitrogen containing monomer, what has a polymerizable functional group which has unsaturated double bonds, such as a (meth) acryloyl group or a vinyl group, and has a cyclic nitrogen structure can be especially used without a restriction | limiting. The cyclic nitrogen structure preferably has a nitrogen atom in the cyclic structure. Examples of cyclic nitrogen-containing monomers include lactam vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinyl Examples thereof include vinyl monomers having a nitrogen-containing heterocyclic ring such as imidazole, vinyl oxazole and vinyl morpholine. Moreover, the (meth) acryl monomer containing heterocyclic rings, such as a morpholine ring, a piperidine ring, a pyrrolidine ring, a piperazine ring, is mentioned. Specific examples include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine and the like. Among the cyclic nitrogen-containing monomers, lactam vinyl monomers are preferable.

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

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

  In the present invention, the hydroxyl group-containing monomer is preferably 1% by weight or more from the viewpoint of enhancing adhesive force and cohesive force with respect to the total amount of the monofunctional monomer component forming the (meth) acrylic polymer, It is more preferably 2% by weight or more, and further preferably 3% by weight or more. On the other hand, if the amount of the hydroxyl group-containing monomer is too large, the pressure-sensitive adhesive layer becomes hard and the adhesive strength may decrease, and the viscosity of the pressure-sensitive adhesive may become too high or gel. The hydroxyl group-containing monomer is preferably 30% by weight or less, more preferably 27% by weight or less, and more preferably 25% by weight or less based on the total amount of the monofunctional monomer component forming the (meth) acrylic polymer. Is more preferable.

  The monomer component forming the (meth) acrylic polymer can contain other functional group-containing monomers as monofunctional monomers. For example, a monomer having a carboxyl group-containing monomer or a cyclic ether group Can be mentioned.

  As the carboxyl group-containing monomer, those having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a carboxyl 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. Can be used alone or in combination. These anhydrides can be used for itaconic acid and maleic acid. Among these, acrylic acid and methacrylic acid are preferable, and acrylic acid is particularly preferable. In addition, a carboxyl group-containing monomer can be arbitrarily used for the monomer component used for manufacture of a (meth) acrylic-type polymer, On the other hand, it is not necessary to use a carboxyl group-containing monomer.

  As a monomer having a cyclic ether group, a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and a cyclic ether group such as an epoxy group or an oxetane group. It can be used without particular limitation. Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate glycidyl ether, and the like. Examples of the oxetane group-containing monomer include 3-oxetanylmethyl (meth) acrylate, 3-methyl-oxetanylmethyl (meth) acrylate, 3-ethyl-oxetanylmethyl (meth) acrylate, and 3-butyl-oxetanylmethyl (meth) acrylate. , 3-hexyl-oxetanylmethyl (meth) acrylate, and the like. These can 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 based on the total amount of the monofunctional monomer component forming the (meth) acrylic polymer, and 27% by weight. % Or less is more preferable, and 25% by weight or less is more preferable.

The monomer component forming the (meth) acrylic polymer includes, for example, CH ₂ ═C (R ¹ ) COOR ² (wherein R ¹ is hydrogen or a methyl group, R ² has 1 to 3 substituted alkyl groups and cyclic cycloalkyl groups.) Alkyl (meth) acrylates.

Here, the substituent of the substituted alkyl group having 1 to 3 carbon atoms as R ² is preferably an aryl group having 3 to 8 carbon atoms or an aryloxy group having 3 to 8 carbon atoms. . The aryl group is not limited, but is preferably a phenyl group.

Examples of such a monomer 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. are mentioned. These can be used alone or in combination.

In the present invention, the (meth) acrylate represented by CH ₂ ═C (R ¹ ) COOR ² is 50% by weight or less based on the total amount of the monofunctional monomer component forming the (meth) acrylic polymer. 45% by weight or less is preferable, 40% by weight or less is more preferable, and 35% by weight or less is more preferable.

  Other copolymer monomers include vinyl acetate, vinyl propionate, styrene, α-methylstyrene; (meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol, (meth) acrylic acid methoxyethylene glycol, (meth) Glycol acrylic ester monomers such as methoxypolypropylene glycol acrylate; Acrylic ester monomers such as tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate, silicone (meth) acrylate and 2-methoxyethyl acrylate; Monomers, amino group-containing monomers, imide group-containing monomers, N-acryloylmorpholine, vinyl ether monomers, and the like can also be used. Moreover, as a copolymerization monomer, the monomer which has cyclic structures, such as terpene (meth) acrylate and dicyclopentanyl (meth) acrylate, can be used.

  Furthermore, the silane type monomer etc. which contain a silicon atom are mentioned. Examples of the silane monomer include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, and 8-vinyloctyltrimethoxysilane. , 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane, and the like.

  The monomer component forming the (meth) acrylic polymer may contain a polyfunctional monomer as necessary in order to adjust the cohesive strength of the pressure-sensitive adhesive in addition to the monofunctional monomer exemplified above. it can.

  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, such as (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 Ester compounds of polyhydric alcohols such as (meth) acrylic acid; allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di (meth) acrylate, hexyl di (meth) ) Acrylate and the like. Among these, trimethylolpropane tri (meth) acrylate, hexanediol di (meth) acrylate, and dipentaerythritol hexa (meth) acrylate can be preferably used. A polyfunctional monomer can be used individually by 1 type or in combination of 2 or more types.

  The amount of the polyfunctional monomer used varies depending on the molecular weight, the number of functional groups, etc., but it is preferably used at 3 parts by weight or less, more preferably 2 parts by weight or less, with respect to 100 parts by weight of the monofunctional monomer in total. 1 part by weight or less is more preferable. Moreover, it does not specifically limit as a lower limit, However It is preferable that it is 0 weight part or more, and it is more preferable that it is 0.001 weight part or more. Adhesive force can be improved when the usage-amount of a polyfunctional monomer exists in the said range.

  In the present invention, a partial polymer of the monomer component may be used. The “partially polymerized product” here is a product obtained by partially polymerizing monomer components. The polymerization rate of the partially polymerized monomer component is as described later.

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

  Although it does not specifically limit as an ultraviolet absorber, For example, a triazine type ultraviolet absorber, a benzotriazole type ultraviolet absorber, a benzophenone type ultraviolet absorber, an oxybenzophenone type ultraviolet absorber, a salicylic acid ester type ultraviolet absorber, a cyanoacrylate type ultraviolet ray An absorbent etc. can be mentioned, These can be used individually by 1 type or in combination of 2 or more types. Among these, triazine-based UV absorbers and benzotriazole-based UV absorbers are preferable, triazine-based UV absorbers having 2 or less hydroxyl groups in one molecule, and benzones having one benzotriazole skeleton in one molecule. Being at least one ultraviolet absorber selected from the group consisting of triazole-based ultraviolet absorbers has good solubility in the monomer used for forming the ultraviolet curable acrylic pressure-sensitive adhesive composition, and This is particularly preferable because of its high ultraviolet absorption capability near a wavelength of 380 nm.

  Specific examples of the triazine-based ultraviolet absorber having two or less hydroxyl groups in one molecule include 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 [(C10-C16 (mainly C12-C13) alkyloxy) methyl] oxirane reaction product (TINUVIN400, manufactured by BASF), 2- [4,6-bis (2, -Dimethylphenyl) -1,3,5-triazin-2-yl] -5- [3- (dodecyloxy) -2-hydroxypropoxy] phenol), 2- (2,4-dihydroxyphenyl) -4,6 -Reaction product of bis- (2,4-dimethylphenyl) -1,3,5-triazine and (2-ethylhexyl) -glycidic acid ester (TINUVIN405, 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), 2- (2-hydroxy-4- [ - can be used octyloxycarbonylethoxy] phenyl) -4,6-bis (4-phenylphenyl) -1,3,5-triazine (TINUVIN 479, manufactured by BASF) and the like.

  Moreover, as a benzotriazole ultraviolet absorber having one benzotriazole skeleton in one molecule, 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), benzene Propanoic acid and ester compound of 3- (2H-benzotriazol-2-yl) -5- (1,1-dimethylethyl) -4-hydroxy (C7-9 side chain and straight chain alkyl) (TINUVIN 384-2, BASF) 2-, (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-fe) Nylethyl) phenol (TINUVIN900, 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), methyl-3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate / polyethylene glycol 300 reaction product (TINUVIN 1130, 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-butyl) phenol (TINUVIN 326, manufactured by BASF), 2- (2H-benzotriazol-2-yl) -4,6-di -Tert-pentylphenol (TINUVIN 328, manufactured by BASF), 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol (TINUVIN 329, manufactured by BASF), methyl 3 -(3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate and polyethylene glycol 300 reaction product (TINUVIN 213, manufactured by BASF), 2- (2H-benzotriazole -2-yl) -6-dodecyl-4-methylphenol ( TINUVIN571, manufactured by BASF), 2- [2-hydroxy-3- (3,4,5,6-tetrahydrophthalimido-methyl) -5-methylphenyl] benzotriazole (Sumsorb 250, manufactured by Sumitomo Chemical Co., Ltd.), etc. Can be used.

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

  Examples of the salicylic acid ester ultraviolet absorber (salicylic acid ester compound) include, for example, phenyl-2-acryloyloxybenzoate, phenyl-2-acryloyloxy-3-methylbenzoate, and phenyl-2-acryloyl. Oxy-4-methylbenzoate, phenyl-2-acryloyloxy-5-methylbenzoate, phenyl-2-acryloyloxy-3-methoxybenzoate, phenyl-2-hydroxybenzoate, phenyl-2- Hydroxy-3-methylbenzoate, phenyl-2-hydroxy-4methylbenzoate, phenyl-2-hydroxy-5-methylbenzoate, phenyl 2-hydroxy-3-methoxybenzoate, 2,4-di- tert-Butylphenyl-3,5-di-tert- Chill-4-hydroxybenzoate (TINUVIN120, manufactured by BASF), and the like.

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

  The ultraviolet absorber may be used alone or in combination of two or more, but the total content is a monofunctional monomer component that forms a (meth) acrylic polymer. The amount is preferably about 0.1 to 5 parts by weight and more preferably about 0.5 to 3 parts by weight with respect to 100 parts by weight. It is preferable to set the addition amount of the ultraviolet absorber within the above range since the ultraviolet absorption function of the pressure-sensitive adhesive layer can be sufficiently exhibited and the ultraviolet polymerization is not hindered.

  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 400 nm or more. The photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more may be any one having an absorption band at a wavelength of 400 nm or more, and may have an absorption band at a wavelength of less than 400 nm. When the ultraviolet light absorber was included in the pressure-sensitive adhesive composition, the ultraviolet light was absorbed by the ultraviolet light absorber and was not sufficiently polymerized. However, since the pressure-sensitive adhesive composition of the present invention has a photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more, it can be sufficiently polymerized even though it contains an ultraviolet absorber.

  As a photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (Irgacure 819, manufactured by BASF), 2,4,6-trimethylbenzoyl- And diphenyl-phosphine oxide (LUCIRIN TPO, manufactured by BASF).

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

  Further, the addition amount of the photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more is not particularly limited, but is preferably smaller than the addition amount of the ultraviolet absorber. The amount is preferably about 0.005 to 1 part by weight and more preferably about 0.02 to 0.5 part by weight with respect to 100 parts by weight of the monofunctional monomer component forming the system polymer. It is preferable that the amount of the photopolymerization initiator (A) added is in the above range because ultraviolet polymerization can sufficiently proceed.

  In addition, the ultraviolet curable acrylic pressure-sensitive adhesive composition of the present invention can contain a photopolymerization initiator (B) having an absorption band at a wavelength of less than 400 nm. Moreover, it is preferable that a photoinitiator (B) does not have an absorption band in wavelength 400nm or more. The photopolymerization initiator (B) is not particularly limited as long as it generates radicals by ultraviolet rays and starts photopolymerization and has an absorption band at a wavelength of less than 400 nm. Any initiator can be suitably used. For example, benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, α-ketol photopolymerization initiator, photoactive oxime photopolymerization initiator, benzoin photopolymerization initiator, benzyl photopolymerization initiator, benzophenone A photopolymerization initiator, a ketal photopolymerization initiator, a thioxanthone photopolymerization initiator, an acylphosphine oxide photopolymerization initiator, or the like can be used.

  Specifically, examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane- Examples include 1-one and anisole methyl ether.

  Examples of the acetophenone photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4-t-butyldichloroacetophenone. Etc.

  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. Is mentioned.

  Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime.

  Examples of the benzoin photopolymerization initiator include benzoin.

  Examples of the benzyl photopolymerization initiator include benzyl.

  Examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like.

  Examples of the ketal photopolymerization initiator include benzyl dimethyl ketal.

  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, dodecylthioxanthone and the like are included.

  Examples of the acylphosphine oxide-based photopolymerization initiator include 2,4,6-trimethylbenzoyl-diphenyl-phosphine 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 400 nm can be used alone or in combination of two or more. The photopolymerization initiator (B) having an absorption band at a wavelength of less than 400 nm can be added within a range that does not impair the effects of the present invention, and the addition amount is a monofunctional that forms a (meth) acrylic polymer. The amount is preferably about 0.005 to 0.5 parts by weight and more preferably about 0.02 to 0.1 parts by weight with respect to 100 parts by weight of the monomeric monomer component.

  In the present invention, a photopolymerization initiator (B) having an absorption band at a wavelength of less than 400 nm is first added to the monomer component, and a partially polymerized monomer component (prepolymer) partially polymerized by irradiation with ultraviolet rays. The composition is preferably subjected to ultraviolet polymerization by adding a photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more and an ultraviolet absorber. When the photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more is added to the partial polymerization product (prepolymer composition) of the monomer component partially polymerized by ultraviolet irradiation, the photopolymerization is started. It is preferable to add the agent after dissolving it in the monomer.

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

  Examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2- (3,4 epoxycyclohexyl). Epoxy group-containing silane coupling agents such as ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1, (3-dimethylbutylidene) propylamine, amino group-containing silane coupling agents such as N-phenyl-γ-aminopropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane ( (Meth) acrylic group-containing silane Coupling agent, 3-isocyanate propyltriethoxysilane isocyanate group-containing silane coupling agents such as and the like.

  The ultraviolet curable acrylic pressure-sensitive adhesive composition of the present invention can contain a crosslinking agent. Examples of crosslinking agents include isocyanate crosslinking agents, epoxy crosslinking agents, silicone crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, silane crosslinking agents, alkyletherified melamine crosslinking agents, metal chelate crosslinking agents, Crosslinkers such as oxides are included. A crosslinking agent can be used alone or in combination of two or more. Among these, an isocyanate type crosslinking agent is preferably used.

The crosslinking agent may be used alone or in combination of two or more, but the total content is a monofunctional monomer that forms a (meth) acrylic polymer. The amount 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 0.02 to 3 parts by weight with respect to 100 parts by weight of the component. It preferred, especially.

  The isocyanate-based crosslinking agent refers to a compound having two or more isocyanate groups (including isocyanate-regenerating functional groups in which isocyanate groups are temporarily protected by a blocking agent or quantification) in one molecule. Examples of the isocyanate-based crosslinking agent include aromatic isocyanates such as tolylene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

  More specifically, for example, lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate, alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate, 2,4-tolylene diisocyanate, Aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, polymethylene polyphenyl isocyanate, trimethylolpropane / tolylene 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.), hexamethylene Isocyanurate of isocyanate (trade name: Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.) and the like, trimethylolpropane adduct of xylylene diisocyanate (trade name: D110N, manufactured by Mitsui Chemicals, Inc.), hexa Trimethylolpropane adduct of methylene diisocyanate (trade name: D160N, manufactured by Mitsui Chemicals); polyether polyisocyanate, polyester polyisocyanate, and adducts of these with various polyols, isocyanurate bond, burette bond, Examples thereof include polyisocyanates polyfunctionalized with allophanate bonds.

  In addition to the above components, the ultraviolet curable acrylic pressure-sensitive adhesive composition of the present invention may contain appropriate additives depending on the application. For example, tackifiers (for example, rosin derivative resins, polyterpene resins, petroleum resins, oil-soluble phenol resins, etc., solid, semi-solid, or liquid at room temperature); fillers such as hollow glass balloons; plasticizers; aging Inhibitors; antioxidants and the like.

  In the present invention, the ultraviolet curable acrylic pressure-sensitive adhesive composition is preferably adjusted to have a viscosity suitable for work such as coating on a substrate. The viscosity of the ultraviolet curable acrylic pressure-sensitive adhesive composition can be adjusted, for example, by adding various polymers such as thickening additives, polyfunctional monomers, etc., or partially adding monomer components in the ultraviolet curable acrylic pressure-sensitive adhesive composition. It is carried out by polymerization. The partial polymerization may be performed before or after adding various polymers such as thickening additives, polyfunctional monomers, and the like. Since the viscosity of the UV curable acrylic pressure-sensitive adhesive composition varies depending on the amount of the additive, etc., the polymerization rate when the monomer component in the UV curable acrylic pressure-sensitive adhesive composition is partially polymerized is uniquely determined. However, as a guideline, it is preferably about 20% or less, more preferably about 3 to 20%, and still more preferably about 5 to 15%. If it exceeds 20%, the viscosity becomes too high, so that it is difficult to apply to the substrate.

  The transmission b * value of the pressure-sensitive adhesive layer formed by the ultraviolet curable acrylic pressure-sensitive adhesive composition of the present invention is not particularly limited, but is preferably 3.0 or less, more preferably 1.5 or less. Preferably, it is 0.5 or less. The b * value refers to the b * value (chromaticity) in the L * a * b * color system according to JIS Z8729. For example, a spectrophotometer (product name: U4100, manufactured by Hitachi High-Technologies Corporation) ).

  The transmittance at a wavelength of 380 nm of the pressure-sensitive adhesive layer formed of the ultraviolet curable acrylic pressure-sensitive adhesive composition of the present invention is 40% or less, preferably 20% or less, and more preferably 8% or less. Since the transmittance wavelength at a wavelength of 380 nm is in the above range, it is possible to sufficiently block incident ultraviolet rays, thereby suppressing deterioration of optical members such as liquid crystal panels, organic EL elements, polarizers, and the like. it can.

  Further, the transmittance at a wavelength of 400 nm of the pressure-sensitive adhesive layer formed by the ultraviolet curable acrylic pressure-sensitive adhesive composition of the present invention is 30% or more, preferably 50% or more, and preferably 70% or more. More preferred. When the excess wavelength at the wavelength of 400 nm is in the above range, it is preferable because sufficient incident visible light can be transmitted and sufficient visibility can be secured in the image display device.

2. UV-curable acrylic pressure-sensitive adhesive layer The UV-curable acrylic pressure-sensitive adhesive layer of the present invention is a pressure-sensitive adhesive layer located between a cover glass or a cover plastic and a polarizing film in an image display device,
It is formed by irradiating the ultraviolet curable acrylic pressure-sensitive adhesive composition with ultraviolet rays to photopolymerize a monomer component in the ultraviolet curable acrylic pressure-sensitive adhesive composition.

  About an ultraviolet curable acrylic adhesive composition, the above-mentioned thing can be used.

As for the illumination intensity of the ultraviolet-ray irradiated to the said ultraviolet curable acrylic adhesive composition, 5 mW / cm < ² > or more is preferable. When the illuminance of the ultraviolet light is less than 5 mW / cm ² , the polymerization reaction time becomes long and the productivity may be inferior. The illuminance of the ultraviolet light is preferably 200 mW / cm ² or less. When the illuminance of the ultraviolet rays exceeds 200 mW / cm ² , the photopolymerization initiator is consumed rapidly, so that the polymer has a low molecular weight, and the holding power particularly at high temperatures may be reduced. Further, the integrated quantity of ultraviolet light ^is preferably ^{100mJ / cm 2 ~5000mJ / cm 2} .

  The ultraviolet lamp used in the present invention is not particularly limited, but an LED lamp is preferable. Since the LED lamp has a lower emission heat than other ultraviolet lamps, the temperature during polymerization of the pressure-sensitive adhesive layer can be suppressed. Therefore, the molecular weight reduction of the polymer can be prevented, the cohesive strength of the pressure-sensitive adhesive layer can be prevented from being lowered, and the holding power at a high temperature when the pressure-sensitive adhesive sheet is used can be increased. It is also possible to combine a plurality of ultraviolet lamps. Further, it is possible to intermittently irradiate ultraviolet rays, and to provide a light period in which ultraviolet rays are irradiated and a dark period in which ultraviolet rays are not irradiated.

  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 this invention, it is preferable that the peak wavelength of the ultraviolet-ray irradiated to the said ultraviolet curable acrylic adhesive composition exists in the range of 200-500 nm, and it is more preferable that it exists in the range of 300-450 nm. When the peak wavelength of ultraviolet rays exceeds 500 nm, the photopolymerization initiator may not be decomposed and the polymerization reaction may not start. On the other hand, if the peak wavelength of the ultraviolet light is less than 200 nm, the polymer chain may be cut and the adhesive properties may be deteriorated.

  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 further preferably 150 μm or more, from the viewpoint of ensuring the ultraviolet absorption function. Although the upper limit of the thickness of an adhesive layer is not specifically limited, It is preferable that it is 10 mm or less. If the thickness of the pressure-sensitive adhesive layer exceeds 10 mm, it is difficult to transmit ultraviolet rays, it takes time to polymerize the monomer component, and productivity may be inferior.

  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 further preferably 85% or more. When the gel fraction of the pressure-sensitive adhesive layer is small, the cohesive force is inferior, and when it is too large, the adhesive force may be inferior.

  The transmission b * value, the transmittance at a wavelength of 380 nm, and the transmittance at a wavelength of 400 nm of the pressure-sensitive adhesive layer are as described above.

  The pressure-sensitive adhesive layer of the present invention is used for an image display device, and more specifically, is located between a cover glass or a cover plastic and a polarizing film in the image display device. When the pressure-sensitive adhesive layer of the present invention is in this position, the ultraviolet absorbing function can be sufficiently exhibited.

3. Polarizing film with pressure-sensitive adhesive layer The polarizing film with a pressure-sensitive adhesive layer of the present invention has a polarizing film and the ultraviolet curable acrylic pressure-sensitive adhesive layer on at least one surface of the polarizing film.

  The method for forming the ultraviolet curable acrylic pressure-sensitive adhesive layer is as described above, and the pressure-sensitive adhesive layer may be formed by applying a direct ultraviolet curable acrylic pressure-sensitive adhesive composition on the polarizing film. After forming the pressure-sensitive adhesive layer on the release film or the like, the pressure-sensitive adhesive layer may be formed on the polarizing film by transferring the pressure-sensitive adhesive layer to the polarizing film.

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

  The polarizer is not particularly limited, and various types can be used. Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples thereof include polyene-based oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be produced by, for example, dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution of potassium iodide or the like which may contain boric acid, zinc sulfate, zinc chloride or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with stains and antiblocking agents by washing the polyvinyl alcohol film with water, the polyvinyl alcohol film is also swollen to prevent unevenness such as uneven coloring. is there. Stretching may be performed after dyeing with iodine, may be performed while dyeing, or may be dyed with iodine after stretching. The film can be stretched even in an aqueous solution of boric acid or potassium iodide or in a water bath.

  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 to 7 μm. Such a thin polarizer is preferable in that the thickness unevenness is small, the visibility is excellent, the dimensional change is small, the durability is excellent, and the thickness of the polarizing film can be reduced.

The thin polarizer, typically 51-069644 Patent and Publication and JP 2000-338329 JP Sho, WO 2010/100917 pamphlet, or and Patent 4751481 Patent 2012 A thin polarizing film described in Japanese Patent No. 073563 can be given. These thin polarizing film, a polyvinyl alcohol-based resin (hereinafter, also referred to as PVA-based resin) layer and can be obtained Ri by the method comprising the step of dyeing the step of stretching the stretched resin base material in a state of the stack. With this production 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.

As the thin polarizing film, International Publication No. 2010/100917 pamphlet in that it can be stretched at a high magnification and the polarization performance can be improved among the production methods including the step of stretching in the state of a laminate and the step of dyeing. , also preferably those obtained by the process comprising the step of stretching in an aqueous boric acid solution, such as a described in Japanese Patent 4751481 Pat and JP 2012-073563, the specification and particularly patent 4,751,481 Patent 2012 What is obtained by the manufacturing method including the process of extending | stretching in the air auxiliary before extending | stretching in the boric-acid aqueous solution as described in -0753563 gazette is preferable.

  As a material for forming a transparent protective film provided on one side or both sides of the polarizer, a material excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is preferable. For example, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene such as polystyrene and acrylonitrile / styrene copolymer (AS resin) And polymers based on polycarbonate and polycarbonate. Also, polyethylene, polypropylene, polyolefins having a cyclo 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 , Polyether sulfone polymer, polyether ether ketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, or Examples of the polymer that forms the transparent protective film include polymer blends. The transparent protective film can also be formed as a cured layer of thermosetting or ultraviolet curable resin such as acrylic, urethane, acrylurethane, epoxy, and silicone.

  Although the thickness of a protective film can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin film property.

  The polarizer and the protective film are usually in close contact with each other through an aqueous adhesive or the like. Examples of the water-based adhesive include an isocyanate-based adhesive, a polyvinyl alcohol-based adhesive, a gelatin-based adhesive, a vinyl-based latex, a water-based polyurethane, and a water-based polyester. In addition to the above, examples of the adhesive between the polarizer and the transparent protective film include an ultraviolet curable adhesive and an electron beam curable adhesive. The electron beam curable polarizing film adhesive exhibits suitable adhesiveness to the various transparent protective films. The adhesive used in the present invention can contain a metal compound filler.

  The surface of the transparent protective film to which the polarizer is not adhered may be subjected to a treatment for the purpose of hard coat layer, antireflection treatment, sticking prevention, diffusion or antiglare.

  Moreover, when the adhesive layer of the polarizing film with an adhesive layer of this invention is exposed, you may protect an adhesive layer with a peeling film (separator) until it uses for practical use. The above-mentioned thing can be mentioned as a peeling film. When a release film is used as a base material in the production of the above-mentioned pressure-sensitive adhesive layer, the release film is adhered to the polarizing film with the pressure-sensitive adhesive layer by laminating the pressure-sensitive adhesive layer on the release film and the polarizing film. It can be used as a release film for the agent layer, and the process can be simplified.

4). The present invention 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),
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 400 nm or more to the partially polymerized monomer component to prepare an ultraviolet curable acrylic pressure-sensitive adhesive composition;
An ultraviolet curable acrylic pressure-sensitive adhesive comprising 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 rays. The present invention relates to a method for producing an agent layer.

  Each component constituting the ultraviolet curable acrylic pressure-sensitive adhesive composition is as described above.

  When forming a pressure-sensitive adhesive layer from an ultraviolet curable acrylic pressure-sensitive adhesive composition containing a photopolymerization initiator (B), first, a monomer component containing an alkyl (meth) acrylate and the photopolymerization initiator (B) The composition containing (sometimes referred to as “pre-added polymerization initiator”) is irradiated with ultraviolet rays to form a partial polymer of the monomer component. The polymerization rate of the partially polymerized product is preferably about 20% or less, more preferably about 3 to 20%, and still more preferably about 5 to 15%. The ultraviolet irradiation conditions are as described above.

  Subsequently, an ultraviolet absorber and a photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more (sometimes referred to as “post-added polymerization initiator”) are added to the partial polymerization product of the monomer component, An ultraviolet curable acrylic pressure-sensitive adhesive composition is prepared. The ultraviolet absorber, the photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more, and the addition amount thereof are as described above.

  The ultraviolet curable acrylic pressure-sensitive adhesive composition thus obtained is applied to at least one side of the substrate, and the ultraviolet curable acrylic pressure-sensitive adhesive composition is irradiated with ultraviolet rays so that an ultraviolet curable acrylic type is obtained. An adhesive layer can be manufactured. The ultraviolet irradiation conditions are as described above.

  The substrate is not particularly limited, and examples thereof include various substrates such as a release film and a transparent resin film substrate, and a polarizing film described later is also preferably used as the substrate. it can.

  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, nets, foam sheets, metal foils, and laminates thereof. However, a resin film is preferably used from the viewpoint of excellent surface smoothness.

  Examples of the resin film include 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, and ethylene. -A vinyl acetate copolymer film etc. are mentioned.

  The thickness of the release film is usually 5 to 200 μm, preferably about 5 to 100 μm. For the release film, if necessary, mold release and antifouling treatment with silicone, fluorine, long chain alkyl or fatty acid amide release agent, silica powder, etc., coating type, kneading type, vapor deposition An antistatic treatment such as a mold can also be performed. In particular, the release property from the pressure-sensitive adhesive layer can be further improved by appropriately performing a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the release film.

  The transparent resin film substrate is not particularly limited, and various resin films having transparency are used. The resin film is formed of a single layer film. For example, the materials 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 resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl alcohol resin, polyarylate resin, polyphenylene sulfide resin, and the like. Of these, polyester resins, polyimide resins and polyethersulfone resins are particularly preferable.

  The thickness of the film base material 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 onto the substrate can be any known appropriate method such as a roll coater, bar coater, or die coater, and is not particularly limited.

  Since the reaction is inhibited by oxygen in the air, in order to block oxygen, a release film or the like is formed on the coating layer of the acrylic pressure-sensitive adhesive composition, or the photopolymerization reaction is performed in a nitrogen atmosphere. Is preferred. In addition, as a peeling film, the above-mentioned thing can be mentioned.

  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), the photopolymerization initiator (B) is first added and the monomer component part is added. A polymer is formed, and an ultraviolet absorber and a photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more are post-added to the partial polymer to prepare an ultraviolet curable acrylic pressure-sensitive adhesive composition. It is preferable. Thus, by polymerizing in two steps, the polymerization rate of the monomer component can be increased, and the ultraviolet ray absorbing function of the finally produced pressure-sensitive adhesive layer can be improved.

5. Image display device The image display device of the present invention has at least a cover glass or a cover plastic and a polarizing film,
The pressure-sensitive adhesive layer is provided between the cover glass or cover plastic and a polarizing film.

  The image display device has at least one polarizing film and at least one cover glass or cover plastic, and the specific configuration is as described above. 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. Among these, a liquid crystal display device having the above-described configuration, an organic paper, and the like. An EL (electroluminescence) display device or the like is 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 addition, all the parts and% in each example are based on weight. Evaluation items in Examples and the like were measured as follows.

Production Example 1 (Production of acrylic pressure-sensitive adhesive composition (a-1))
Photopolymerization started on 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). 1-hydroxycyclohexyl phenyl ketone (trade name: Irgacure 184, manufactured by BASF) 0.035 parts by weight, 2,2-dimethoxy-1,2-diphenylethane-1-one as an agent (pre-added photopolymerization initiator) (Product name: Irgacure 651, manufactured by BASF) 0.035 parts by weight, and then ultraviolet rays until the viscosity (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30 ° C.) is about 20 Pa · s. To obtain a prepolymer composition (polymerization rate: 8%) in which a part of the monomer component was polymerized. Next, 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.) are added to the prepolymer composition. Then, an acrylic pressure-sensitive adhesive composition (a-1) was obtained by irradiating with ultraviolet rays.

Production Example 2 (Production of acrylic pressure-sensitive adhesive composition (a-2))
Butyl acrylate (BA) 67 parts by weight, cyclohexyl acrylate (CHA) 14 parts by weight, 4-hydroxybutyl acrylate (4HBA) 19 parts by weight, 2,2-dimethoxy-1,2-diphenyl-1- ON (product name: Irgacure 651, manufactured by BASF Japan) 0.09 parts by weight and 1-hydroxy-cyclohexyl-phenyl-ketone (product name: Irgacure 184, manufactured by BASF Japan) 0.09 parts by weight A partially polymerized product (monomer syrup) having a polymerization rate of 10% was obtained by putting it into a flask and partially photopolymerizing it by exposing it to ultraviolet rays in a nitrogen atmosphere. Next, 0.15 part by weight of dipentaerythritol penta and hexaacrylate (DPHA) and a silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) are added to the partial polymer. Were added, mixed, and irradiated with ultraviolet light to obtain an acrylic pressure-sensitive adhesive composition (a-2).

Example 1
2,4-bis-[{4- (4-ethylhexyloxy) -4-hydroxy} -phenyl dissolved in butyl acrylate so as to have a solid content of 15% in the acrylic pressure-sensitive adhesive composition (a-1) ] -6- (4-Methoxyphenyl) -1,3,5-triazine (trade name: Tinosorb S, manufactured by BASF Japan Ltd.) and bis (2,4,6) as a post-addition polymerization initiator -Trimethylbenzoyl) -phenylphosphine oxide (trade name: Irgacure 819, manufactured by BASF Japan) 0.2 part was added and stirred to obtain an ultraviolet curable acrylic pressure-sensitive adhesive composition.

The UV curable acrylic pressure-sensitive adhesive composition is applied onto the release-treated surface of the release film so that the thickness after forming the pressure-sensitive adhesive layer is 150 μm, and then an application layer is formed. A release film was bonded to the surface of the layer. Then, ultraviolet irradiation was performed under the conditions of illuminance: 6.5 mW / cm ² and light amount: 1500 mJ / cm ² to photocur the coating layer, thereby forming an adhesive sheet having release films on both sides of the adhesive layer.

Examples 2-16, Comparative Examples 1-6
Except that the type of acrylic pressure-sensitive adhesive composition used, the ultraviolet absorber, the type and amount of post-added photopolymerization initiator, and the thickness after forming the pressure-sensitive adhesive layer are as shown in Table 1, Examples In the same manner as in Example 1, an ultraviolet curable acrylic pressure-sensitive adhesive composition was prepared, and a pressure-sensitive adhesive sheet was formed. However, for 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, an ultraviolet curable acrylic pressure-sensitive adhesive composition was prepared. The formation of was not performed.

In Table 1,
a-1 represents the acrylic pressure-sensitive adhesive composition (a-1) obtained in Production Example 1,
a-2 is the acrylic pressure-sensitive adhesive composition (a-2) obtained in Production Example 2.
Tinosorb S is 2,4-bis-[{4- (4-ethylhexyloxy) -4-hydroxy} -phenyl] -6- (4-methoxyphenyl) -1,3,5-triazine (manufactured by BASF). The
Tinuvin 928 is 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol (manufactured by BASF). The
LA-F70 is 2,4,6-tris (2-hydroxy-4-hexyloxy-3-methylphenyl) -1,3,5-triazine (manufactured by ADEKA),
KEMISORB 279 is 2,2′-methylenebis [6- (benzotriazol-2-yl) -4-tert-octylphenol] (manufactured by Chemipro Kasei Co., Ltd.),
Irgacure 819: bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (trade name, manufactured by BASF Japan Ltd.), having an absorption band at a wavelength of 200 to 450 nm,
Irgacure 651: 2,2-dimethoxy-1,2-diphenylethane-1-one (trade name, manufactured by BASF Japan Ltd.), having an absorption band at a wavelength of 200 to 380 nm,
Irgacure 184: 1-hydroxy-cyclohexyl-phenyl-ketone (trade name, manufactured by BASF Japan), having an absorption band at a wavelength of 200 to 370 nm,
Is shown.

  The following evaluation was performed about the obtained adhesive sheet.

<Solubility>
Each ultraviolet absorber used in Examples and Comparative Examples was added in the number of parts described in Table 1 with respect to 100 parts by weight of the acrylic pressure-sensitive adhesive composition shown in Table 1, and visually observed for solubility. Evaluation was made according to the criteria.
○: The ultraviolet absorber was dissolved in the acrylic pressure-sensitive adhesive composition without being dissolved.
X: The ultraviolet absorber has remained undissolved in the acrylic pressure-sensitive adhesive composition.

<Polymerization rate>
The release films on both sides 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 the weighed aluminum petri dish. The weight of (aluminum petri dish + adhesive layer) was measured, and the weight of the adhesive layer before drying was determined. After drying at 130 ° C. for 2 hours and cooling at room temperature for about 20 minutes, the weight of (aluminum petri dish + adhesive) was measured again to determine the weight of the adhesive layer after drying. The polymerization rate was determined by the following calculation formula.

<Gel fraction>
About 0.1 g of the pressure-sensitive adhesive layer was collected from the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples and wrapped in a porous tetrafluoroethylene sheet (trade name: NTF1122, manufactured by Nitto Denko Corporation) having an average pore diameter of 0.2 μm. After that, it was bound with a kite string, the weight at that time was measured (Zg), and this weight was defined as the weight before immersion. The weight before immersion is the total weight of the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer collected above), the tetrafluoroethylene sheet, and the kite string. The total weight of the tetrafluoroethylene sheet and the kite string was also measured (Yg). Next, a pressure-sensitive adhesive layer wrapped with a tetrafluoroethylene sheet and tied with a 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. Thereafter, a sample (after ethyl acetate treatment) was taken out from the container, transferred to an aluminum cup, dried in a dryer at 130 ° C. for 2 hours to remove ethyl acetate, and then weighed (Xg). The weight was defined as the weight after immersion. The gel fraction was calculated from the following formula.
Gel fraction (% by weight) = (XY) / (ZY) × 100

<Measurement of transmittance and b * value>
The release films on both sides of the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were peeled off, the pressure-sensitive adhesive layer was attached to a measuring jig, and a spectrophotometer (product name: U4100, manufactured by Hitachi High-Technologies Corporation) It was measured.

<Optical reliability of single adhesive layer>
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: 1.3 mm, size: 45 mm × 50 mm, Matsunami Glass Industry ( Manufactured by the same company) and autoclaving (atmospheric pressure: 0.5 MPa, temperature: 50 ° C.) was carried out for 15 minutes. The transmittance and color after being put into the following various reliability conditions 1 to 5 were measured with U4100 (product name) manufactured by Hitachi High-Technologies Corporation, and the amount of change in transmittance from the initial stage was determined. Evaluation was performed according to the following evaluation criteria.
(Various reliability conditions)
(Condition 1) 85 ° C. × 500 h
(Condition 2) −40 ° C. × 500 h
(Condition 3) 60 ° C., 95% × 500 h
(Condition 4) Heat shock (HS) (−40 ° C. to 85 ° C.) × 300 cycles (Condition 5) Under UV irradiation × 100 h, Illuminance: 500 W / cm ² (300 to 700 nm), Environmental temperature: 60 to 65 ° C. Environmental humidity: 50%
(Evaluation criteria)
A: The transmittance change amount is 0.2% or less.
○: The transmittance change amount exceeds 0.2% and is 0.7% or less.
(Triangle | delta): The transmittance | permeability change amount exceeds 0.7% and is 1.0% or less.
X: The transmittance change amount exceeds 1.0%.

<Visibility>
A polarizing film having a TAC film (25 μm) subjected to hard coating treatment on one surface of a polarizer having a thickness of 12 μm and an acrylic film (20 μm) on the other surface of the polarizer was prepared. The release films on both sides of the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples are peeled off, and the pressure-sensitive adhesive layer is bonded onto each protective film 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.) were bonded to obtain a measurement sample. The obtained measurement sample was autoclaved (atmospheric pressure: 0.5 MPa, temperature: 50 ° C.) for 15 minutes. It measured with the ultraviolet visible near-infrared spectrophotometer (product name: V7100, JASCO Corporation make), measured the color, and evaluated on the following evaluation criteria.
◯: b value is 1.4 or more and 3.4 or less Δ: b value exceeds 3.4 and 3.9 or less ×: b value exceeds 3.9

<Durability>
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: 1.3 mm, size: 45 mm × 50 mm, Matsunami Glass Industry ( (Made by Co., Ltd.) was bonded together to obtain a measurement sample. The obtained measurement sample was autoclaved (atmospheric pressure: 0.5 MPa, temperature: 50 ° C.) for 15 minutes. Various reliability conditions shown in Table 1 (Condition 1: 85 ° C. × 500 h, Condition 2: −40 ° C. × 500 h, Condition 3: 60 ° C. 95% × 500 h, Condition 4: HS (−40 ° C. to 85 ° C.) × 300 Cycle, condition 5: under UV irradiation × 100 h), the evaluation sample was measured with a magnifying glass or an electron microscope. Evaluation was made according to the following evaluation criteria.
◯: No peeling from the end and no foaming.
X: Peeling and foaming occurred.

<UV resistance (polarizing film protection function)>
A polarizing film is prepared in which one surface of a polarizer having a thickness of 12 μm is protected by a TAC film (25 μm) subjected to a hard coat treatment, and the other surface of the polarizer is protected by an acrylic film (20 μm). did. On each protective film of the polarizing film, the release films on both sides of the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were peeled off and the pressure-sensitive adhesive layers were bonded together. : S200200, thickness: 1.3 mm, size: 45 mm × 50 mm, produced by Matsunami Glass Industry Co., Ltd.) was used as a measurement sample. The obtained measurement sample was autoclaved (atmospheric pressure: 0.5 MPa, temperature: 50 ° C.) for 15 minutes. Then, UV irradiation conditions of illuminance: 500 W / cm ² (300 to 700 nm), environmental temperature: 60 to 65 ° C., environmental humidity: 50% were applied, and an ultraviolet-visible near-infrared spectrophotometer (product name: V7100, Japan) And the change in transmittance from the initial stage was determined. Evaluation was performed according to the following evaluation criteria.
A: The transmittance change amount is 1.0% or less.
○: The transmittance change amount exceeds 1.0% and is 2.0% or less.
(Triangle | delta): The transmittance | permeability change amount exceeds 2.0% and is 3.0% or less.
X: The transmittance change amount exceeds 3.0%.

DESCRIPTION OF SYMBOLS 1 Cover glass or cover plastic 2a-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

Claims (4)

Monomer component containing alkyl (meth) acrylate and / or partial polymer of the monomer component, ultraviolet absorber, photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more, and absorption band at a wavelength of less than 400 nm A method for producing a pressure-sensitive adhesive layer formed from an ultraviolet curable acrylic pressure-sensitive adhesive composition containing a photopolymerization initiator (B) ,
Irradiating a composition containing a monomer component containing an alkyl (meth) acrylate and a photopolymerization initiator (B) having an absorption band at a wavelength of less than 400 nm to form a partially polymerized product of the monomer component,
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 partially polymerized monomer component to prepare an ultraviolet curable acrylic pressure-sensitive adhesive composition;
The ultraviolet-curable acrylic pressure-sensitive adhesive composition was coated on at least one side of the substrate, it viewed including the step of irradiating ultraviolet rays to the ultraviolet-curable acrylic pressure-sensitive adhesive composition,
The obtained pressure-sensitive adhesive layer is disposed between the cover glass or the cover plastic in the image display device and the polarizing film, has a transmittance of 40% or less at a wavelength of 380 nm, and a transmittance of 30% or more at a wavelength of 400 nm. A method for producing an ultraviolet curable acrylic pressure-sensitive adhesive layer, comprising: The method for producing an ultraviolet curable acrylic pressure-sensitive adhesive layer according to claim 1, wherein a transmission b * value of the pressure-sensitive adhesive layer is 3.0 or less. The ultraviolet absorber is at least selected from the group consisting of a triazine-based ultraviolet absorber having 2 or less hydroxyl groups in one molecule and a benzotriazole-based ultraviolet absorber having one benzotriazole skeleton in one molecule. The method for producing an ultraviolet curable acrylic pressure-sensitive adhesive layer according to claim 1 or 2, wherein the ultraviolet curable acrylic pressure-sensitive adhesive layer is one type of ultraviolet absorber. The method for producing an ultraviolet curable acrylic pressure-sensitive adhesive layer according to any one of claims 1 to 3, wherein the addition amount of the photopolymerization initiator (A) is less than the addition amount of the ultraviolet absorber. .

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