JP5586497B2 - Adhesive composition for optical member, adhesive layer, optical member provided with adhesive layer, image display device with optical member, and method of manufacturing image display device - Google Patents

Description

  The present invention relates to an adhesive composition for an optical member, an adhesive layer, an optical member provided with an adhesive layer, an image display device with such an optical member, and a method for manufacturing the image display device. , Regarding.

  Optical members used in the liquid crystal display device, such as a polarizing plate and a retardation plate, are attached to the liquid crystal cell using an adhesive. Such an optical material has a large expansion and contraction under conditions of heat and humidity, and the accompanying floating and peeling are likely to occur. For this reason, the pressure-sensitive adhesive for optical members is required to have durability that can cope with heating conditions and humidification conditions.

  Moreover, when affixing to a liquid crystal cell, various processing processes, such as a punching process and a slit process, are made in the state in which the adhesive was bonded to the optical member. In such a case, since the adhesive may be taken off by the cutting blade or protrude from the cut surface, it is necessary to perform an aging treatment, which significantly impedes productivity. That is, it is advantageous in terms of productivity that such processing can be performed quickly after an optical member with an adhesive is manufactured.

  As such optical pressure-sensitive adhesives, pressure-sensitive adhesives of various compositions have been proposed, and when the various optical members, liquid crystal panels, various light sources, diffusion plates, etc. are bonded together, their transparency and weather resistance are high. An acrylic pressure-sensitive adhesive is used because it is good.

  10 to 100 parts by weight of a low molecular weight acrylic polymer having a weight average molecular weight of 3 to 100,000 having a glass transition temperature of 0 to -80 ° C. with respect to 100 parts by weight of a high molecular weight acrylic polymer having a weight average molecular weight of 100 to 2.5 million. A pressure-sensitive adhesive composition containing 0.001 to 10 parts by weight of a polyfunctional compound has been proposed (Patent Document 1). It is described that the pressure-sensitive adhesive composition improved in durability by adding a component having a high glass transition temperature can prevent the occurrence of peeling, foaming and whitening phenomenon, and is excellent in reworkability. However, even with the proposed content, durability and reworkability are insufficient, and particularly in the case of a liquid crystal cell having a large size, gap breakage easily occurs because reworkability is insufficient.

  There are two or more glass transition temperature peaks, a difference in glass transition temperature between them is 70 ° C. or higher, and a graft or block pressure-sensitive adhesive having a glass transition temperature on the high temperature side of 50 ° C. or higher is disclosed. It is said that it is excellent in cutting property and cutting property (Patent Document 2). An acrylic pressure-sensitive adhesive grafted with polydimethylsiloxane has also been proposed, and it is said that the adhesive residue at the time of peeling is good and the durability is excellent (Patent Document 3). However, there are problems such as deterioration of initial adhesiveness and a limit to the amount of introduction. In addition, in the case of graft polymerization, there is a problem that the degree of freedom in polymer synthesis is small because a technique of copolymerizing a so-called macromonomer having an acryloyl group or a methacryloyl group at the end of the graft chain is used. .

  Further, by sticking the optical member to the image display device with a liquid adhesive, problems such as uniformity of thickness, protrusion of the adhesive, misalignment, and shrinkage of curing may occur.

JP 2002-121521 A Japanese Patent Laid-Open No. 7-82542 JP-A-10-168407

  The present invention provides an adhesive composition for an optical member that is excellent in durability and can suppress deformation of the optical member even under severe conditions for a long period of time, and an adhesive layer for an optical member using the same. For the purpose.

  Another object of the present invention is to provide an optical member provided with such an adhesive layer, an image display device with such an optical member, and a method for manufacturing the image display device.

  As a result of intensive studies to solve the above problems, the present inventors have found the following adhesive layer and completed the present invention.

  That is, the present invention relates to a modified acrylic graft polymer obtained by graft polymerization of a chain containing a cyclic ether group-containing monomer to a (meth) acrylic polymer; 0.05 to 10 parts by weight of a photopolymerization initiator or thermosetting The present invention relates to an adhesive composition comprising 0.05 to 10 parts by weight of a catalyst; and 0.01 to 5 parts by weight of an isocyanate-based crosslinking agent.

  Such an adhesive composition comprises a (meth) acrylic polymer, 100 parts by weight of a modified acrylic graft polymer obtained by graft polymerization of a chain containing a cyclic ether group-containing monomer; It may contain 10 parts by weight; 0.05 to 5 parts by weight of a sensitizer; and 0.01 to 5 parts by weight of an isocyanate-based crosslinking agent.

  The graft polymer is obtained by graft polymerizing 100 parts by weight of the (meth) acrylic polymer with 2 to 100 parts by weight of the cyclic ether group-containing monomer in the presence of 0.01 to 2 parts by weight of a peroxide. Can be obtained.

  The photopolymerization initiator may be a photocationic initiator that generates protons by photolysis.

  The present invention also relates to an adhesive layer obtained from any of the above adhesive compositions.

  The present invention also relates to an optical member with an adhesive layer in which the adhesive layer is formed on at least one side of a support.

  The present invention also relates to a cured adhesive layer obtained by irradiating or heat-treating an active energy ray to the adhesive layer.

  The gel fraction of the cured adhesive layer may be 75 to 97% by weight.

  The gel fraction of the cured adhesive layer is preferably higher by 10% by weight or more than the gel fraction of the adhesive layer before irradiation with active energy rays or before heat treatment.

  The present invention also relates to an image display device having any one of the above cured adhesive layers.

The present invention also provides a (meth) acrylic polymer, 100 parts by weight of a modified acrylic graft polymer obtained by graft polymerization of a chain containing a cyclic ether group-containing monomer, 0.05 to 10 parts by weight of a photopolymerization initiator, and isocyanate. Applying an adhesive composition containing 0.01 to 5 parts by weight of a system cross-linking agent to at least one surface of an optical member;
A step of irradiating the applied adhesive composition layer with active energy rays; and a step of attaching the obtained cured pressure-sensitive adhesive layer to an image display device;
The manufacturing method of an image display apparatus containing this.

The present invention also provides 100 parts by weight of a modified acrylic graft polymer obtained by graft polymerization of a chain containing a cyclic ether group-containing monomer to a (meth) acrylic polymer, 0.05 to 10 parts by weight of a photopolymerization initiator, and sensitization. Applying a pressure-sensitive adhesive composition comprising 0.05 to 5 parts by weight of an agent and 0.01 to 5 parts by weight of an isocyanate-based crosslinking agent to at least one surface of the optical member;
A step of affixing the obtained cured adhesive layer to an image display device; and a step of irradiating active energy rays from the optical member side;
The present invention relates to a method for manufacturing an image display device.

  In the manufacturing method of the image display device, the adhesive layer may be attached to the image display device within a period of 1 second to 60 minutes after irradiation with the active energy ray.

The present invention also provides a (meth) acrylic polymer, 100 parts by weight of a modified acrylic graft polymer obtained by graft polymerization of a chain containing a cyclic ether group-containing monomer, 0.05 to 10 parts by weight of a thermosetting catalyst, and an isocyanate-based polymer. A step of applying an adhesive composition containing 0.01 to 5 parts by weight of a crosslinking agent on a support, further heat-treating it, and then applying it to at least one surface of the optical member; and the obtained curing A process of attaching the adhesive layer to the image display device;
The present invention relates to a method for manufacturing an image display device.

  The adhesive composition of the present invention and the adhesive layer obtained therefrom are excellent in durability even under long-term severe conditions while maintaining good processability and ease of handling. Furthermore, an optical member using such an adhesive layer is not easily deformed.

  The present inventors have added 100 parts by weight of a modified acrylic polymer composition grafted with a monomer having a cyclic ether group in the presence of a base polymer (meth) acrylic polymer, and a photopolymerization initiator or a thermosetting catalyst 0. It has been found that a pressure-sensitive adhesive composition for an optical member comprising at least 05 parts by weight and at least 0.01 parts by weight of an isocyanate-based crosslinking agent maintains processability and handling properties by crosslinking with an isocyanate-based crosslinking agent. It was. By irradiating the adhesive layer obtained from such a composition with radiation and adhering it to the image display device, the epoxy group curing reaction is completed, so that it has excellent durability and optical properties even under long-term severe conditions. It was found that the deformation of the member could be suppressed, and the cured adhesive layer having such a configuration was used.

As the monomer unit contained in the (meth) acrylic polymer, any (meth) acrylate can be used and is not particularly limited. Here, it is preferable that, for example, an alkyl (meth) acrylate having an alkyl group having 2 or more carbon atoms is contained in an amount of 50% by weight or more of the total (meth) acrylic polymer.

  In the present specification, the term “alkyl (meth) acrylate” simply refers to a (meth) acrylate having a linear or branched alkyl group. The alkyl group preferably has 2 or more carbon atoms, more preferably 2 to 14 carbon atoms. (Meth) acrylate refers to acrylate and / or methacrylate, and (meth) of the present invention has the same meaning.

  Specific examples of the alkyl (meth) acrylate include n-butyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, and isopentyl. (Meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl ( (Meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, isomyristyl (meth) acrylate, n-tridecyl (meth) acrylate Rate, n- tetradecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate. Especially, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc. can be illustrated and these can be used individually or in combination.

  In this invention, the said alkyl (meth) acrylate is 50 weight% or more with respect to all the monomer components of a (meth) acrylic-type polymer, Preferably it is 80 weight% or more, More preferably, it is 90 weight% or more. The alkyl (meth) acrylate is preferably 99.8% by weight or less, and may be 98% by weight or less or 97% by weight or less.

  The (meth) acrylic polymer of the present invention preferably contains a hydroxyl group-containing monomer containing at least one hydroxyl group in the alkyl group. That is, this monomer is a hydroxyalkyl (meth) acrylate monomer containing one or more hydroxyalkyl groups. Here, the hydroxyl group is preferably present at the terminal of the alkyl group. Carbon number of an alkyl group becomes like this. Preferably it is 4-12, More preferably, it is 4-8, More preferably, it is 4-6. By including such a hydroxyalkyl (meth) acrylate monomer, the position where hydrogen abstraction occurs during graft polymerization and the compatibility between the graft polymer and the homopolymer of the cyclic ether group-containing monomer produced during graft polymerization are achieved. It has a positive effect and is believed to help prepare a graft polymer with good heat resistance.

As such a monomer, a monomer having a polymerizable functional group having an unsaturated double bond of a (meth) acryloyl group and having a hydroxyl group can be used without particular limitation. For example, 2-hydroxyethyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxy Examples thereof include hydroxyalkyl (meth) acrylates such as octyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate and the like. Of these, hydroxyalkyl (meth) acrylate is preferably used.
When the hydroxyl group-containing monomer is contained with respect to the total amount of the monomer components forming the (meth) acrylic polymer, it is preferably 0.1% by weight or more, more preferably 0.2% by weight or more, and still more preferably. It is 0.5% by weight or more, preferably 10% by weight or less, more preferably 7% by weight or less, and further preferably 5% by weight or less.

  As the monomer component for forming the (meth) acrylic polymer, other monomers can be used alone or in combination as long as the object of the present invention is not impaired.

For example, an unsaturated carboxylic acid-containing monomer can be used in addition to the monomer. As the unsaturated carboxylic acid-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 carboxyl group can be used without particular limitation. Examples of the unsaturated carboxylic acid-containing monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. These can be used alone or in combination. Among these, it is preferable to use (meth) acrylic acid, particularly acrylic acid.

  The unsaturated carboxylic acid-containing monomer is preferably used in a proportion of 0.1 to 20% by weight, more preferably 0.2 to 10% by weight, based on the total amount of monomer components forming the (meth) acrylic polymer. More preferably, it is 0.5 to 7% by weight. Within this range, it is possible to obtain a composition having good adhesiveness and moderate viscosity.

  Other examples of the copolymer monomer include acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; styrene sulfonic acid and allyl sulfonic acid, 2- (meth) acrylamide- Sulfonic acid group-containing monomers such as 2-methylpropanesulfonic acid, (meth) acrylamidepropanesulfonic acid, sulfopropyl (meth) acrylate, and (meth) acryloyloxynaphthalenesulfonic acid; Phosphoric acid group-containing monomers such as 2-hydroxyethylacryloyl phosphate And (meth) acrylic acid alkoxyalkyl monomers such as (meth) acrylic acid methoxyethyl and (meth) acrylic acid ethoxyethyl;

  In addition, vinyl monomers such as vinyl acetate, vinyl propionate, styrene, α-methylstyrene, N-vinylcaprolactam; glycidyl (meth) acrylate, methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) Epoxy group-containing monomers such as acrylate; glycol-based acrylic ester monomers such as (meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol, (meth) acrylic acid methoxyethylene glycol, (meth) acrylic acid methoxypolypropylene glycol; Acrylic ester monomers such as tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate, silicone (meth) acrylate and 2-methoxyethyl acrylate; Bromide group-containing monomers, amino group-containing monomers, imide group-containing monomer, N- acryloyl morpholine, 2-hydroxyethyl (meth) acrylate, can be used 2-hydroxyethyl (meth) acrylamide, also vinyl ether monomers.

  Furthermore, a monomer having an amino group, an imide group or an amide group can also be used. Examples of such monomers include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethylacrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, and N-butoxy. Methyl (meth) acrylamide, dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, (meth) acrylonitrile, N- (meth) acryloylmorpholine, N-vinyl-2-pyrrolidone, N-cyclohexyl Examples include maleimide, N-phenylmaleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-butylmaleimide, N-hexylmaleimide and the like. These nitrogen-containing monomers are contained in an amount of 0.1 to 20% by weight, preferably 0.5 to 15% by weight, and more preferably 2 to 10% by weight. By using a nitrogen-containing monomer within this range, peeling is unlikely to occur at high humidity, and adhesion is improved.

  The weight average molecular weight of the (meth) acrylic polymer of the present invention is preferably 600,000 or more, more preferably 700,000 to 3,000,000. The weight average molecular weight is a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.

Such a (meth) acrylic polymer can be produced by appropriately selecting a known production method such as solution polymerization, bulk polymerization, emulsion polymerization, and various radical polymerizations. Further, the (meth) acrylic polymer obtained may be either a random copolymer or a block copolymer.

  In solution polymerization, for example, ethyl acetate, toluene or the like is used as a polymerization solvent. As a specific example of solution polymerization, the reaction is performed under an inert gas stream such as nitrogen, and a polymerization initiator is added, and the reaction is usually performed at about 50 to 70 ° C. under reaction conditions of about 5 to 30 hours.

  The polymerization initiator, chain transfer agent, emulsifier and the like used for radical polymerization are not particularly limited and can be appropriately selected and used. In addition, the weight average molecular weight of a (meth) acrylic-type polymer can be controlled by the usage-amount of a polymerization initiator and a chain transfer agent, and reaction conditions, The usage-amount is suitably adjusted according to these kinds.

  Examples of the polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [2- (5-methyl-2). -Imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2'-azobis (N, N'-dimethyleneisobutylamidine), 2,2 '-Azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (manufactured by Wako Pure Chemical Industries, VA-057) and other azo initiators, and persulfates such as potassium persulfate and ammonium persulfate , Di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butyl -Oxydicarbonate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3 , 3-tetramethylbutylperoxy-2-ethylhexanoate, di (4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butylperoxyisobutyrate, 1,1-di (t-hexylperoxy) ) Peroxides such as cyclohexane, t-butyl hydroperoxide, hydrogen peroxide, peroxides and sodium bisulfite, peroxides and sodium ascorbate Redox initiators combined with Not intended to be.

  The polymerization initiator may be used alone or in combination of two or more, but the total content is 0.005 to 1 part by weight with respect to 100 parts by weight of the monomer. Is preferably about 0.02 to 0.5 parts by weight.

  In order to produce the (meth) acrylic polymer having the weight average molecular weight using, for example, 2,2′-azobisisobutyronitrile as the polymerization initiator, the amount of the polymerization initiator used is a monomer. The total amount of the components is preferably about 0.06 to 0.3 parts by weight, more preferably about 0.08 to 0.2 parts by weight.

  Examples of the chain transfer agent include lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propanol. The chain transfer agent may be used alone or in combination of two or more, but the total content is 0.1 parts by weight with respect to 100 parts by weight of the total amount of monomer components. Less than or equal to

  Examples of the emulsifier used in emulsion polymerization include anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, ammonium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, and polyoxy Nonionic emulsifiers such as ethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, and polyoxyethylene-polyoxypropylene block polymer are listed. These emulsifiers may be used alone or in combination of two or more.

  Further, as reactive emulsifiers, as emulsifiers into which radical polymerizable functional groups such as propenyl groups and allyl ether groups are introduced, specifically, for example, Aqualon HS-10, HS-20, KH-10, BC-05 BC-10, BC-20 (all of which are manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adeka Soap SE10N (manufactured by ADEKA), and the like. Reactive emulsifiers are preferable because they are incorporated into the polymer chain after polymerization and thus have improved water resistance. The amount of the emulsifier used is more preferably 0.3 to 5 parts by weight and 0.5 to 1 part by weight from the viewpoint of polymerization stability and mechanical stability with respect to 100 parts by weight of the total amount of monomer components.

The glass transition temperature (Tg) of the (meth) acrylic polymer is 250K or less, preferably 240K or less. The glass transition temperature is also preferably 200K or higher. When the glass transition temperature is 250 K or less, the adhesive composition has good heat resistance and excellent internal cohesive strength. Such a (meth) acrylic polymer can be adjusted by appropriately changing the monomer component and composition ratio to be used. Such glass transition temperature is, for example, by solution polymerization, using 0.06-0.3 parts by weight of a polymerization initiator such as azobisisobityronitrile or benzoyl peroxide, and using a polymerization solvent such as ethyl acetate. It is obtained by reacting at 50 ° C. to 70 ° C. for 8 to 30 hours under a nitrogen stream. Here, the glass transition temperature (Tg) is calculated from the following Fox equation.
1 / Tg = W1 / Tg1 + W2 / Tg2 + W3 / Tg3 +
The above-mentioned Tg1, Tg2, Tg3 and the like represent the glass transition temperatures of the individual copolymer components 1, 2, 3, etc. in absolute temperature, and W1, W2, W3 and the like represent the respective copolymer components. The weight fraction. In addition, the glass transition temperature (Tg) of the single polymer was obtained from Polymer Handbook (4th edition, John Wiley & Sons. Inc.).

Next, a solution obtained by diluting the (meth) acrylic polymer thus obtained as it is or by adding a diluent is subjected to graft polymerization.

Although it does not specifically limit as a diluent, Ethyl acetate or toluene is illustrated.

Graft polymerization is carried out by reacting a (meth) acrylic polymer with a cyclic ether group-containing monomer and optionally a cyclic ether group-containing monomer and other monomers.

Here, the cyclic ether group-containing monomer is not particularly limited, but is preferably an epoxy group-containing monomer, an oxetane group-containing monomer, or a combination of both.

Examples of the epoxy group-containing monomer include 4-hydroxybutyl glycidyl acrylate, glycidyl acrylate, glycidyl methacrylate, 3,4-epoxycyclohexylmethyl acrylate, 3,4-epoxycyclohexylmethyl methacrylate, or 4-hydroxybutyl acrylate glycidyl ether. These can be used alone or in combination.

Examples of the oxetane group-containing monomer include 3-oxetanylmethyl (meth) acrylate, 3-methyl-3-oxetanylmethyl (meth) acrylate, 3-ethyl-3-oxetanylmethyl (meth) acrylate, and 3-butyl-3-oxetanylmethyl. (Meth) acrylate or 3-hexyl-3-oxetanylmethyl (meth) acrylate is exemplified, and these can be used alone or in combination.

The amount of the cyclic ether group-containing monomer is preferably 2 parts by weight or more, more preferably 3 parts by weight or more with respect to 100 parts by weight of the (meth) acrylic polymer. The upper limit is not particularly limited, but is preferably 100 parts by weight or less, more preferably 50 parts by weight or less, and most preferably 30 parts by weight. When the amount of the cyclic ether group-containing monomer is 2 parts by weight or more, the function of the composition as a pressure-sensitive adhesive is sufficiently exhibited. On the other hand, when the amount is 100 parts by weight or more, tackiness is reduced and initial adhesion is difficult. There is.

  It is also possible to use other monomers that co-graft with the cyclic ether group-containing monomer during the graft polymerization. Such a monomer is not particularly limited as long as it does not contain a cyclic ether group, and examples thereof include alkyl (meth) acrylates having 1 to 9 carbon atoms. Specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl acrylate and the like. Moreover, alicyclic (meth) acrylates such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate can also be used. These can be used alone or in combination.

When other monomers co-grafted at the time of grafting are used, the irradiation amount at the time of light irradiation for curing the adhesive can be lowered. This is presumably because the mobility of the graft chain is increased, or because the compatibility between the graft chain and the by-product ungrafted chain and the backbone polymer is improved.

Such other monomers are also preferably selected from the same monomers as the main chain (trunk), that is, the components of the (meth) acrylic polymer.

When blended, the amount of other monomers other than the cyclic ether group-containing monomer is 90:10 to 10:90, preferably 80:20 to 20:80, by weight ratio to the cyclic ether group. . If the content of other monomers is small, the effect of lowering the light irradiation amount for curing may not be sufficient, and if it is large, the peeling resistance after light irradiation may increase.

Graft polymerization conditions are not particularly limited, and can be carried out by methods known to those skilled in the art. In the polymerization, it is preferable to use a peroxide as a polymerization initiator.

The amount of such a polymerization initiator is 0.02 to 5 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. When the amount of this polymerization initiator is small, it takes too much time for the graft polymerization reaction, and when it is large, many homopolymers of cyclic ether group-containing monomers are formed, which is not preferable.

For example, if the graft polymerization is solution polymerization, a cyclic ether group-containing monomer and a viscosity-adjustable solvent are added to the acrylic polymer solution, followed by nitrogen substitution, and then a peroxide system such as dibenzoyl peroxide. Although it can carry out by adding 0.02-5 weight part of polymerization initiators, and heating at 50 to 80 degreeC for 4 to 15 hours, it is not limited to this.

The state of the obtained graft polymer (molecular weight, branch polymer branch size, etc.) can be appropriately selected depending on the reaction conditions.

  The adhesive composition of the present invention contains the graft polymer thus obtained, a photopolymerization initiator or a thermosetting catalyst, and an isocyanate-based crosslinking agent.

  Here, the photopolymerization initiator is preferably a photocationic polymerization initiator that generates protons by photolysis. As the photocationic polymerization initiator, any photocationic polymerization initiator known to those skilled in the art can be preferably used. More specifically, allylsulfonium salts and allyliodonium salts are commercially available, and are allylsulfonium hexafluorophosphate salt, sulfonium hexafluorophosphate, bis (alkylphenyl) iodonium hexafluorophosphate, bis (dodecyl). Phenyl) iodonium hexafluoroantimonate, bis (t-butylphenyl) iodonium hexafluorophosphate, bis (t-butylphenyl) iodonium trifluoromethanesulfonate, triphenylsulfonium trifluoromethanesulfonate, biphenyliodonium trifluoromethanesulfonate A small amount selected from the group consisting of phonate and phenyl- (3-hydroxy-pentadecylphenyl) iodonium hexafluoroantimonate It is possible to use the Kutomo one.

  Such a cationic photopolymerization initiator may be used alone or in combination of two or more, but the total content is 100 weight of the (meth) acrylic polymer. 0.05 parts by weight or more, preferably 0.1 parts by weight or more, more preferably 0.3 parts by weight or more, and 10 parts by weight or less, preferably 5 parts by weight or less. More preferably, it is 3 parts by weight or less.

  In the present invention, when a photocationic polymerization initiator is used, a sensitizer can be further used so that protons are generated even with ultraviolet rays having a long wavelength. As such a sensitizer, a thioxanthone sensitizer or an anthracene compound may be used. In many cases, an ultraviolet absorber is blended in the optical member. Therefore, 9,10-dibutoxyanthracene, which has absorption at a long wavelength and can propagate energy to the photocationic polymerization initiator, Anthracene compounds such as dipropoxyanthracene and 9,10-diethoxyanthracene are more preferably used. By adding a sensitizer to the adhesive composition of the present invention, ultraviolet light is irradiated from above the optical member containing the ultraviolet absorber even after the adhesive layer is attached to the image display device. Even so, protons are generated from the photocationic polymerization initiator, and the curing reaction of the cyclic ether group is initiated.

  In the present invention, a thermosetting catalyst may be used instead of the photopolymerization initiator. As such a thermosetting catalyst, a thermosetting catalyst having a cyclic ether group is used. More specifically, examples include imidazole compounds, acid anhydrides, phenol resins, Lewis acid complexes, amino resins, polyamines, melamine resins, and microencapsulated bodies thereof. You can choose.

  Such cyclic ether group thermosetting catalysts may be used alone or in admixture of two or more. Content of a thermosetting catalyst is 0.2-10 weight part with respect to 100 weight part of (meth) acrylic-type polymers, Preferably, it is 0.3-5 weight part.

  In particular, an imidazole compound is preferably used because it exhibits an effect even when the addition amount is small. Examples of the imidazole compound include 2 methyl imidazole, 2 heptadecyl imidazole, 1,2-dimethyl imidazole, 2 phenyl imidazole, 2 phenyl 4 methyl imidazole, 1 benzyl 2 methyl imidazole, and the like. It is selected in consideration of compatibility.

For example, when the pressure-sensitive adhesive polymer is a water-dispersed emulsion, 1,2-dimethylimidazole is selected, and 1-cyanoethyl 2-undecyl is selected for the purpose of preserving storage or for heat curing at a relatively high temperature. If imidazole is selected and the purpose is to cure at a relatively low temperature, it is preferable to select 2-phenylimidazole.

Although it does not specifically limit as an isocyanate type crosslinking agent contained in an adhesive composition, The isocyanate group (The isocyanate reproduction type functional group which protected the isocyanate group temporarily by the blocking agent or quantification etc. is included) is 1 Examples thereof include isocyanate-based crosslinking agents that are compounds having two or more in the 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.), tri Methylolpropane / hexamethylene diisocyanate trimer adduct (product name: Coronate HL, manufactured by Nippon Polyurethane Industry Co., Ltd.), hexamethylene diiso Isocyanurate of anate (product name: Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.), polyether polyisocyanate, polyester polyisocyanate, and adducts of these with various polyols, isocyanurate bond, burette bond And polyisocyanates polyfunctionalized with allophanate bonds. Of these, it is preferable to use an aliphatic isocyanate because of its high reaction rate.

The isocyanate-based crosslinking agent may be used alone or in combination of two or more, but the total content is 100 parts by weight of the (meth) acrylic polymer. On the other hand, the isocyanate compound crosslinking agent is preferably contained in an amount of 0.01 to 5 parts by weight, more preferably 0.02 to 2 parts by weight, and more preferably 0.05 parts by weight. More preferably, the content is 1.5 parts by weight or less. It can be appropriately contained in consideration of crosslinking stability, processability, handling properties, and the like.

  Moreover, you may use together an organic type crosslinking agent and a polyfunctional metal chelate as a crosslinking agent. Examples of the organic crosslinking agent include epoxy crosslinking agents (referring to compounds having two or more epoxy groups in one molecule). Examples of the epoxy-based crosslinking agent include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, terephthalic acid diglycidyl ester acrylate, spiroglycol diglycidyl ether, and the like. These may be used alone or in combination of two or more.

  A polyfunctional metal chelate is one in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, and the like. can give. Examples of the atom in the organic compound that is covalently or coordinately bonded include an oxygen atom, and the organic compound includes an alkyl ester, an alcohol compound, a carboxylic acid compound, an ether compound, a ketone compound, and the like.

  In the present invention, it is also possible to add an oxazoline-based crosslinking agent or peroxide as a crosslinking agent.

  As the oxazoline-based crosslinking agent, those having an oxazoline group in the molecule can be used without particular limitation. The oxazoline group may be any of a 2-oxazoline group, a 3-oxazoline group, and a 4-oxazoline group. As the oxazoline-based cross-linking agent, a polymer obtained by copolymerizing an unsaturated monomer with an addition-polymerizable oxazoline is preferable, and a compound using 2-isopropenyl-2-oxazoline as the addition-polymerizable oxazoline is particularly preferable. As an example, trade name “Epocross WS-500” manufactured by Nippon Shokubai Co., Ltd. can be cited.

The peroxide can be used as appropriate as long as it generates radical active species by heating and proceeds with crosslinking of the base polymer of the adhesive composition, but in consideration of workability and stability, It is preferable to use a peroxide having a one-minute half-life temperature of 80 ° C. to 160 ° C., and more preferable to use a peroxide having a 90 ° C. to 140 ° C.

  Examples of peroxides that can be used include di (2-ethylhexyl) peroxydicarbonate (1 minute half-life temperature: 90.6 ° C.), di (4-t-butylcyclohexyl) peroxydicarbonate (1 Minute half-life temperature: 92.1 ° C.), di-sec-butyl peroxydicarbonate (1 minute half-life temperature: 92.4 ° C.), t-butyl peroxyneodecanoate (1 minute half-life temperature: 103 0.5 ° C), t-hexyl peroxypivalate (1 minute half-life temperature: 109.1 ° C), t-butyl peroxypivalate (1 minute half-life temperature: 110.3 ° C), dilauroyl peroxide ( 1 minute half-life temperature: 116.4 ° C.), di-n-octanoyl peroxide (1 minute half-life temperature: 117.4 ° C.), 1,1,3,3-tetramethylbutyl Oxy-2-ethylhexanoate (1 minute half-life temperature: 124.3 ° C), di (4-methylbenzoyl) peroxide (1 minute half-life temperature: 128.2 ° C), dibenzoyl peroxide (half-minute for 1 minute) Period temperature: 130.0 ° C.), t-butyl peroxyisobutyrate (1 minute half-life temperature: 136.1 ° C.), 1,1-di (t-hexylperoxy) cyclohexane (1 minute half-life temperature: 149.2 ° C.). Especially, since the crosslinking reaction efficiency is excellent, di (4-t-butylcyclohexyl) peroxydicarbonate (1 minute half-life temperature: 92.1 ° C.), dilauroyl peroxide (1 minute half-life temperature: 116. 4 ° C), dibenzoyl peroxide (1 minute half-life temperature: 130.0 ° C) and the like are preferably used.

  The peroxide half-life is an index representing the decomposition rate of the peroxide, and means the time until the remaining amount of peroxide is reduced to half. The decomposition temperature for obtaining a half-life at an arbitrary time and the half-life time at an arbitrary temperature are described in the manufacturer catalog, for example, “Organic peroxide catalog 9th edition by Nippon Oil & Fats Co., Ltd.” (May 2003) ".

  The peroxide may be used alone or as a mixture of two or more, but the total content is based on 100 parts by weight of the (meth) acrylic polymer. The peroxide is contained in an amount of 0.01 to 2 parts by weight, preferably 0.04 to 1.5 parts by weight, and 0.05 to 1 part by weight. More preferably. In order to adjust processability, reworkability, cross-linking stability, peelability, and the like, it is appropriately selected within this range.

  In addition, as a measuring method of the peroxide decomposition amount which remained after the reaction process, it can measure by HPLC (high performance liquid chromatography), for example.

More specifically, for example, after about 0.2 g of the adhesive composition after reaction treatment is taken out, immersed in 10 ml of ethyl acetate, and extracted by shaking at 25 ° C. and 120 rpm for 3 hours with a shaker. Let stand at room temperature for 3 days. Next, 10 ml of acetonitrile was added, shaken at 120 rpm at 25 ° C. for 30 minutes, and about 10 μl of the extract obtained by filtration through a membrane filter (0.45 μm) was injected into the HPLC for analysis. The amount of peroxide can be set.

  Although the adhesive layer is formed by the crosslinking agent, in the formation of the adhesive layer, the addition amount of the entire crosslinking agent is adjusted, and the influence of the crosslinking treatment temperature and the crosslinking treatment time is sufficiently considered. There is a need.

  The adhesive composition of the present invention may further contain an epoxy resin or an oxetane resin in order to further improve the adhesive strength and heat resistance.

Examples of the epoxy resin include bisphenol A type, bisphenol F type, bisphenol S type, brominated bisphenol A type, hydrogenated bisphenol A type, bisphenol AF type, biphenyl type, naphthalene type, fluorene type, phenol novolac type, cresol novolac type. Examples thereof include bifunctional epoxy resins such as trishydroxyphenylmethane type and tetraphenylolethane type and polyfunctional epoxy resins, and glycidylamine types such as hydantoin type and trisglycidyl isocyanurate type. These epoxy resins can be used alone or in combination of two or more.

  These epoxy resins are not limited, but commercially available epoxy resins can be used. Examples of such commercially available epoxy resins include, but are not limited to, for example, bisphenol type epoxy resins such as Japan Epoxy Resin Co., Ltd. jER828, jER806, etc .; alicyclic epoxy resins such as Japan Epoxy Resin Co., Ltd. YX8000, YX8034, etc. ADEKA Co., Ltd. EP4000, EP4005, etc .; polyglycidyl ethers of polyalcohols include known epoxy resins such as Nagase ChemteX Corporation Denacol EX-313, EX-512, EX-614B, EX-810, etc. .

Examples of the oxetane resin include xylylene oxetane such as 1,4-bis {[(3-ethyl-3-oxetanyl) methoxy] methyl} benzene, 3-ethyl-3-{[3-ethyloxetane-3-yl] methoxy. } Methyl} oxetane, 3-ethylhexyloxetane, 3-ethyl-3-hydroxyoxetane, 3-ethyl-3-hydroxymethyloxetane, and other known oxetane resins can be used. These oxetane resins can be used singly or in combination of two or more.

The oxetane resin is not limited, but a commercially available resin can be used. Examples of such commercially available oxetane resins include Aron Oxetane OXT-121, OXT221, OXT101, and OXT212 manufactured by Toa Gosei Co., Ltd., but are not limited thereto.

Such an epoxy resin and an oxetane resin can be used in the adhesive composition of the present invention by either one or a combination of both.

In the present invention, the epoxy resin and / or the oxetane resin can be blended in this way, and the total amount thereof is preferably 5 parts by weight or more when included with respect to 100 parts by weight of the graft polymer. Preferably, it is 10 parts by weight or more, preferably 100 parts by weight or less, more preferably 70 parts by weight or less. When the amount of the epoxy resin and / or oxetane resin and other tackifier is within this range, a remarkable effect on the adhesive force is recognized, and the curing is sufficient.

In addition, a tackifier, a softener, etc. can be mix | blended with the adhesive composition of this invention. These tackifiers and softeners may be used in a total amount of 10 to 100 parts by weight, preferably 20 to 80 parts by weight, based on 100 parts by weight of the (meth) acrylic polymer.

In particular, for the purpose of adjusting the refractive index of the pressure-sensitive adhesive layer, a tackifier having an aromatic ring and having a refractive index in the range of 1.51 to 1.75 may be used. The colored tackifier is not preferable for coloring the pressure-sensitive adhesive, and a transparent tackifier can be used. As a measure of the transparency, the Gardner hue is 1 or less in a 50% toluene solution. Specifically, styrene oligomer, phenoxyethyl acrylate oligomer, copolymer of styrene and α-methylstyrene, copolymer of vinyltoluene and α-methylstyrene, hydrogenated product of C9 petroleum resin, hydrogenated product of terpene phenol, And hydrogenated products of rosin and its derivatives. At this time, a tackifier having a softening point of 40 ° C. or lower is used in an amount of less than 30 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer, and is used in combination with a tackifier having a softening point of 50 ° C. or higher. It is preferable in terms of heat resistance that it is used in an amount of 20 parts by weight (total 50 parts by weight) or more.
The compounding amount of these tackifiers is 10 to 100 parts by weight, preferably 20 to 80 parts by weight, and is adjusted to a predetermined refractive index. If the amount is too small, the refractive index will not increase sufficiently, and if it is too large, it will become hard and the adhesiveness will deteriorate, which is not preferable.

Furthermore, a terpene resin to which phenol is added (terpene phenol resin) can also be used. There is also an advantage that heat resistance is improved by reaction with phenol.

Furthermore, when the pressure-sensitive adhesive made of this acrylic polymer composition is applied to a hydrophilic adherend such as glass, a silane coupling agent is added in an amount of 0.01 to 1 weight in order to increase the water resistance at the interface. Partial blending may be used.

Examples of the silane coupling agent include epoxy group-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane. Amino group-containing silane cups such as 3-aminopropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine Ring agents, (meth) acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, and isocyanate group-containing silane coupling agents such as 3-isocyanatopropyltriethoxysilane, Etc. It is done. The silane coupling agent is preferably 0.01 parts by weight or more and preferably 1 part by weight or less with respect to 100 parts by weight of the (meth) acrylic polymer. More preferably, it is 0.02 parts by weight or more and 0.6 parts by weight or less. Most preferably, it is 0.05 parts by weight or more and 0.3 parts by weight or less. If it is this range, the adhesive force to a liquid crystal cell will be controlled moderately, it is excellent in removability, and durability will increase.

In addition, the adhesive composition of the present invention may contain other known additives such as powders such as colorants and pigments, dyes, surfactants, plasticizers, and tackiness. Agents, surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particles, foils, etc. It can add suitably according to the use to be used. Moreover, you may employ | adopt the redox system which added a reducing agent within the controllable range.

The method for forming the adhesive layer of the present invention is not particularly limited, but preferably, it is first applied to a release liner or the like which has been subjected to a release treatment, dried and removed from the polymerization solvent, etc. Energy beam irradiation is performed to form an adhesive layer. As a constituent material of the release liner, for example, a porous substrate made of paper, cloth, nonwoven fabric, polyethylene, polypropylene, polyethylene terephthalate, polybutene, polybutadiene, polymethylpentene, polyvinyl chloride, vinyl chloride copolymer, polybutylene terephthalate, Examples thereof include plastic films or sheets such as polyurethane and ethylene-vinyl acetate copolymer, nets, foams, metal foils, and suitable thin leaves such as laminates thereof. Among these, a plastic film is preferably used from the viewpoint of excellent surface smoothness.

The thickness of the release liner is usually about 5 to 200 μm, preferably about 5 to 100 μm. For release liners, release, antifouling treatment with silicone, fluorine, long chain alkyl or fatty acid amide release agent, silica powder, etc., coating type, kneading type, vapor deposition type It is also possible to carry out antistatic treatment such as. In particular, the release property from the adhesive layer can be further improved by appropriately performing a release treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment on the surface of the release liner.

Various methods are used as a method for forming the adhesive layer. Specifically, for example, roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Examples thereof include an extrusion coating method.

  The thickness of the adhesive layer is not particularly limited and is, for example, about 2 to 100 μm. Preferably, it is 3-70 micrometers, More preferably, it is 5-50 micrometers, More preferably, it is 5-35 micrometers.

  As a method for drying and removing the polymerization solvent and the like, an appropriate method can be appropriately employed depending on the purpose. Preferably, a method of heating and drying the coating film is used. The heat drying temperature is preferably 40 ° C to 200 ° C, more preferably 50 ° C to 180 ° C, and particularly preferably 70 ° C to 170 ° C. By setting the heating temperature within the above range, an adhesive having excellent adhesive properties can be obtained. As the drying time, an appropriate time can be adopted as appropriate. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

  The adhesive layer thus obtained is irradiated with active energy rays.

The active energy rays for irradiation are not particularly limited, but are preferably active energy rays such as ultraviolet rays, visible light, and electron beams. The crosslinking treatment by ultraviolet irradiation can be performed using an appropriate ultraviolet source such as a high-pressure mercury lamp, a low-pressure mercury lamp, an excimer laser, or a metal halide lamp. In this case, the irradiation amount of ultraviolet rays can be appropriately selected according to the required degree of crosslinking, but it is usually preferable to select within the range of 0.2 to 10 J / cm ² for ultraviolet rays. . The temperature at the time of irradiation is not particularly limited, but is preferably up to about 140 ° C. in consideration of the heat resistance of the support. The amount of light was expressed as an integrated amount of UVA (320-390 nm), UVB (280-320 nm), UVC (250-260 nm), and UVV (395-445 nm) of UVPowerPuck manufactured by Electronic Instrumentation and Technology Inc.

  In the present invention, an adhesive layer is formed on a support such as a polarizing plate to produce an optical member with an adhesive layer. Then, after irradiating an active energy ray, it is set as a cured adhesive layer, Then, it can be set as an image display apparatus, for example by affixing on a liquid crystal cell etc. It is preferable that the time from irradiating the active energy ray to adhering the cured adhesive layer to the liquid crystal cell is 1 second to 60 minutes. Photocation curing proceeds by the generation of cationic species due to a photoreaction during irradiation with active energy rays and a dark reaction in which a cyclic ether group reacts with the generated cationic species. Therefore, since the cation generated by irradiation with active energy rays has a long lifetime, the reaction can proceed without being deactivated after irradiation, and there is a delay of up to 60 minutes. In the case where bubbles are mixed at the time of bonding, the bubbles can be removed by decompression or pressurization.

In order to promote the dark reaction, it is preferable to heat after pasting, but it is necessary to set the temperature so as not to affect the performance of the image display device. Specifically, it is about 40 minutes to 70 ° C. and about 30 minutes to 6 hours.

  In the adhesive composition of the present invention, when a sensitizer is added, an adhesive layer is formed on a support such as a polarizing plate to produce an optical member with an adhesive layer. Thereafter, when there is no foreign matter biting or misalignment after being attached to a liquid crystal cell or the like, an active energy ray is irradiated from the optical member side to cure the pressure-sensitive adhesive, whereby an image display device can be obtained. Although it can be easily peeled off before irradiation with active energy rays, it is also possible to exhibit the characteristics that after the irradiation with active energy rays, the adhesiveness is increased, the adhesiveness is strongly increased, and the adhesive can be firmly bonded.

  In such irradiation from the optical member, a metal halide lamp or a gallium lamp that can irradiate ultraviolet rays having a relatively long wavelength is preferably used in consideration of the influence of the ultraviolet absorbent in the optical member.

  The gel fraction of the cured adhesive layer of the present invention after irradiation with such an active energy ray is 75 to 97% by weight and becomes a pressure-sensitive adhesive layer having a very high cohesive force. It is -95 weight%, More preferably, it is the range of 85-95 weight%. The gel fraction after heat drying of the adhesive composition before irradiation with active energy rays or heat treatment is preferably in the range of 40 to 85% by weight from the viewpoint of initial adhesiveness, workability, and handling surface. More preferably, it is in the range of 50 to 85% by weight, more preferably 55 to 85% by weight.

  In the case of using a thermosetting catalyst, after the heat treatment, an adhesive layer is formed on a support such as a polarizing plate to produce an optical member with an adhesive layer. Further, for example, by sticking to a liquid crystal cell or the like, an image display device can be obtained.

  The cured adhesive layer of the present invention refers to the state after irradiation or heat treatment with active energy rays, but in the gel fraction of the adhesive layer before irradiation or heat treatment with active energy rays. Compared to the gel fraction, the difference is preferably 10% by weight or more, more preferably 15 to 55% by weight, and still more preferably 15 to 50% by weight. If it is this range, it has the especially outstanding adhesive characteristic.

  As a result, the cured pressure-sensitive adhesive layer of the present invention can be affixed to various image display elements, and is excellent in adhesiveness and cohesive force as well as long-term durability.

  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. Unless otherwise specified, the room temperature standing conditions are all 23 ° C. and 65% RH (1 hour or 1 week).

Example 1
(Preparation of acrylic polymer A1)
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 97 parts by weight of n-butyl acrylate, 3 parts by weight of 4-hydroxybutyl acrylate, and 2,2′-azobis as a polymerization initiator After charging 0.1 parts by weight of isobutyronitrile with 200 parts by weight of ethyl acetate, introducing nitrogen gas with gentle stirring and replacing with nitrogen for 1 hour, the liquid temperature in the flask was kept at around 55 ° C. for 10 hours. A polymerization reaction was performed to prepare an acrylic polymer A1 solution having a weight average molecular weight of 1,600,000. The glass transition temperature of the obtained acrylic polymer was -45 ° C.

(Preparation of graft polymer)
The resulting acrylic polymer A1 solution was diluted with ethyl acetate to a solid content of 25% to prepare a diluted solution (I). 4-hydroxybutyl acrylate glycidyl ether (4HBAGE manufactured by Nippon Kasei Chemical Co., Ltd.) 10 parts by weight with respect to 400 parts by weight of the diluted solution (I) in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser And 10 parts by weight of 2-ethylhexyl acrylate and 0.2 parts by weight of benzoyl peroxide were introduced, nitrogen gas was introduced with gentle stirring, and the atmosphere was purged with nitrogen for 1 hour, and then the liquid temperature in the flask was kept at around 65 ° C. A polymerization reaction was performed for 4 hours and then at 70 ° C. for 4 hours to obtain a graft-modified acrylic polymer B1 solution.

(Formation of polarizing plate C1 with adhesive layer)
Subsequently, allylsulfonium hexafluorophosphate (manufactured by LAMBERTI, ESACURE 1064) as a photopolymerization initiator is used for 100 parts by weight of the solid content of the graft-modified acrylic polymer B1 solution graft polymer solution thus obtained. 5 parts by weight and 0.2 parts by weight of xylylene diisocyanate trimethylolpropane adduct (Mitsui Chemicals, D110N) were blended to prepare an adhesive solution.

On the one side of a 38 μm polyethylene terephthalate (PET) film (MRF-38, manufactured by Mitsubishi Plastics Co., Ltd.) obtained by subjecting the above adhesive solution to silicone release treatment, the thickness of the adhesive layer after drying is 25 μm. And dried at 120 ° C. for 3 minutes to form an adhesive layer having a thickness of 25 μm.

Next, the adhesive layer was transferred to the surface of the polarizing plate to produce a polarizing plate C1 with an adhesive layer. The gel fraction before ultraviolet irradiation was 78% by weight.

(Lamination to image display device)
The PET film was peeled off, and 1 J / cm ² ultraviolet irradiation was performed with a metal halide type UV lamp (manufactured by Fission Co., Ltd., D bulb: lamp emphasizing the 350 to 400 nm region). After the irradiation, it was attached to a liquid crystal cell as an image display device. The time from UV irradiation to bonding was 10 seconds. The gel fraction of the cured adhesive layer after UV irradiation was 95% by weight.

Example 2
(Lamination on image display device)
The above polarizing plate C1 with adhesive layer is irradiated with 1 J / cm ² ultraviolet rays through a PET film with a metal halide type ultraviolet irradiation device (Fusion Co., Ltd., D bulb), and the PET film is peeled off. It was attached to a liquid crystal cell which is an image display device. The time from UV irradiation to bonding was 20 seconds. The gel fraction after UV irradiation was 90% by weight.

Example 3
(Lamination on image display device)
The above polarizing plate C1 with adhesive layer is irradiated with 1 J / cm ² ultraviolet rays through a PET film with a metal halide type ultraviolet irradiation device (Fusion Co., Ltd., D bulb), and the PET film is peeled off. It was attached to a liquid crystal cell which is an image display device. The time from ultraviolet irradiation to bonding was 30 minutes. The gel fraction after UV irradiation was 90% by weight.

Example 4
(Preparation of acrylic polymer A2)
As a polymerization initiator, 83 parts by weight of n-butyl acrylate, 14 parts by weight of methoxyethyl acrylate, 3 parts by weight of 4-hydroxybutyl acrylate are added to a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser. After charging 0.1 part by weight of 2,2′-azobisisobutyronitrile with 200 parts by weight of ethyl acetate, nitrogen gas was introduced while gently stirring, and the atmosphere was purged with nitrogen for 1 hour. The polymerization reaction was carried out for 10 hours while maintaining the temperature at around 0 ° C. to prepare an acrylic polymer A2 solution having a weight average molecular weight of 1.6 million. The glass transition temperature of the obtained acrylic polymer was -43 ° C.

(Preparation of graft-modified acrylic polymer B2)
The resulting acrylic polymer A2 solution was diluted with ethyl acetate to a solid content of 25% to prepare a diluted solution (I). In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a condenser, 10 parts by weight of 4-hydroxybutyl acrylate glycidyl ether, 10 parts by weight of 2-ethylhexyl acrylate with respect to 400 parts by weight of the diluted solution (I) Part by weight and 0.2 part by weight of benzoyl peroxide were added, nitrogen gas was introduced with gentle stirring, and the atmosphere was purged with nitrogen for 1 hour. Then, the liquid temperature in the flask was kept at around 65 ° C. for 4 hours, and then 70 ° C. A polymerization reaction was carried out for 4 hours to obtain a graft-modified acrylic polymer B2 solution.

(Formation of polarizing plate C2 with adhesive layer)
Next, 0.5 parts by weight of allylsulfonium hexafluorophosphate (LAMBERTI, ESACURE 1064) is used as a photopolymerization initiator with respect to 100 parts by weight of the solid content of the graft-modified acrylic polymer B2 solution thus obtained. And 0.2 parts by weight of trimethylolpropane adduct (Mitsui Chemicals, D110N) of xylylene diisocyanate, 0.1 weight of 3-glycidoxypropyltrimethoxysilane (Shin-Etsu Chemical, KBM403) as a silane coupling agent Part was blended to prepare an adhesive solution.

On the one side of a 38 μm polyethylene terephthalate (PET) film (MRF-38, manufactured by Mitsubishi Plastics Co., Ltd.) obtained by subjecting the above adhesive solution to silicone release treatment, the thickness of the adhesive layer after drying is 25 μm. And dried at 120 ° C. for 3 minutes to form an adhesive layer having a thickness of 25 μm.

Next, the adhesive layer was transferred to the surface of the polarizing plate to produce a polarizing plate C2 with an adhesive layer. The gel fraction before UV irradiation was 66% by weight.

(Lamination to image display device)
The PET film was peeled off, and 1 J / cm ² ultraviolet irradiation was performed with a metal halide type UV lamp (D-bulb manufactured by Fission). After irradiation, the cured adhesive layer was attached to a liquid crystal cell as an image display device. The time from UV irradiation to bonding was 10 seconds. The gel fraction after UV irradiation was 88% by weight.

Example 5
(Lamination on image display device)
The above polarizing plate C2 with an adhesive layer is irradiated with 3J / cm ² ultraviolet rays through a PET film with a metal halide type ultraviolet irradiation device (Future Co., Ltd., D bulb), and the PET film is peeled off. It was attached to a liquid crystal cell which is an image display device. The time from UV irradiation to bonding was 10 minutes. The gel fraction after UV irradiation was 96% by weight.

Example 6
(Preparation of graft-modified acrylic polymer B3)
The resulting acrylic polymer A1 solution was diluted with ethyl acetate to a solid content of 25% to prepare a diluted solution (I). In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a cooler, 10 parts by weight of 3,4-epoxycyclohexylmethyl methacrylate and 10 parts by weight of methoxyethyl acrylate with respect to 400 parts by weight of the diluted solution (I) Part by weight and 0.2 part by weight of benzoyl peroxide were added, nitrogen gas was introduced with gentle stirring, and the atmosphere was purged with nitrogen for 1 hour. The liquid temperature in the flask was kept at around 65 ° C. for 4 hours, and then 70 ° C. The polymerization reaction was carried out for 4 hours to obtain a graft-modified acrylic polymer B3 solution.

(Formation of polarizing plate C3 with adhesive layer)
Next, 0.5 parts by weight of allylsulfonium hexafluorophosphate (LAMBERTI, ESACURE 1064) is used as a photopolymerization initiator with respect to 100 parts by weight of the solid content of the graft-modified acrylic polymer B3 solution thus obtained. And 0.2 parts by weight of trimethylolpropane adduct (Mitsui Chemicals, D110N) of xylylene diisocyanate, 0.1 weight of 3-glycidoxypropyltrimethoxysilane (Shin-Etsu Chemical, KBM403) as a silane coupling agent Part was blended to prepare an adhesive solution.

On the one side of a 38 μm polyethylene terephthalate (PET) film (MRF-38, manufactured by Mitsubishi Plastics Co., Ltd.) obtained by subjecting the above adhesive solution to silicone release treatment, the thickness of the adhesive layer after drying is 25 μm. And dried at 120 ° C. for 3 minutes to form an adhesive layer having a thickness of 25 μm.

Next, the adhesive layer was transferred to the surface of the polarizing plate to prepare a polarizing plate C3 with an adhesive layer. The gel fraction before UV irradiation was 73% by weight.

(Lamination to image display device)
The above polarizing plate with adhesive layer C3 is irradiated with 1 J / cm ² ultraviolet rays through a PET film through a metal halide type UV lamp (manufactured by Fission Co., Ltd., D bulb), and the PET film is peeled off. Affixed to the liquid crystal cell. The time from UV irradiation to bonding was 20 seconds. The gel fraction after UV irradiation was 91% by weight.

Example 7
(Preparation of graft-modified acrylic polymer B4)
The resulting acrylic polymer A1 solution was diluted with ethyl acetate to a solid content of 25% to prepare a diluted solution (I). In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a cooler, 10 parts by weight of 3,4-epoxycyclohexylmethyl methacrylate and 10 parts by weight of oxetane methacrylate with respect to 400 parts by weight of the diluted solution (I) Then, 10 parts by weight of 2-ethylhexyl acrylate and 0.2 parts by weight of benzoyl peroxide were added, nitrogen gas was introduced with gentle stirring, and the atmosphere was purged with nitrogen for 1 hour, and then the liquid temperature in the flask was kept at around 65 ° C. For 4 hours and then at 70 ° C. for 4 hours to obtain a graft-modified acrylic polymer B4 solution.

(Formation of polarizing plate C4 with adhesive layer)
Next, 0.5 parts by weight of allylsulfonium hexafluorophosphate (LAMBERTI, ESACURE 1064) is used as a photopolymerization initiator with respect to 100 parts by weight of the solid content of the graft-modified acrylic polymer B3 solution thus obtained. And 0.1 parts by weight of xylylene diisocyanate trimethylolpropane adduct (Mitsui Chemicals, D110N) were blended to prepare an adhesive solution.

On the one side of a 38 μm polyethylene terephthalate (PET) film (MRF-38, manufactured by Mitsubishi Plastics Co., Ltd.) obtained by subjecting the above adhesive solution to silicone release treatment, the thickness of the adhesive layer after drying is 25 μm. And dried at 120 ° C. for 3 minutes to form an adhesive layer having a thickness of 25 μm.

Next, the adhesive layer was transferred to the surface of the polarizing plate to produce a polarizing plate C4 with an adhesive layer. The gel fraction before UV irradiation was 53% by weight.

(Lamination to image display device)
The above-mentioned polarizing plate with adhesive layer C4 is irradiated with ³ J / cm ² ultraviolet rays through a PET film with a metal halide type UV lamp (manufactured by Fission Co., Ltd., D bulb), and the PET film is peeled off. Affixed to the liquid crystal cell. The time from UV irradiation to bonding was 20 seconds. The gel fraction after UV irradiation was 87% by weight.

(Example 8)
(Formation of polarizing plate C5 with adhesive layer)
0.5 weight of allylsulfonium hexafluorophosphate (manufactured by LAMBERTI, ESACURE 1064) as a photopolymerization initiator based on 100 parts by weight of the solid content of the graft-modified acrylic polymer B2 solution obtained in the same manner as in Example 4. Part and 0.5 part by weight of 9,10-dibutoxyanthracene (UVS-1331 manufactured by Kawasaki Kasei Kogyo Co., Ltd.), 0.1 part by weight of xylylene diisocyanate trimethylolpropane adduct (Mitsui Chemicals, D110N), As a silane coupling agent, 0.1 part by weight of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., KBM403) was blended to prepare an adhesive solution.

  The obtained adhesive solution was applied to one side of a 38 μm polyethylene terephthalate (PET) film (MRF-38, manufactured by Mitsubishi Plastics) subjected to silicone release treatment, and the thickness of the adhesive layer after drying was 25 μm. It was applied so that it was dried at 120 ° C. for 3 minutes to form an adhesive layer having a thickness of 25 μm.

  Next, the adhesive layer was transferred to the surface of the polarizing plate to prepare a polarizing plate C5 with an adhesive layer. The gel fraction before ultraviolet irradiation was 64% by weight.

(Lamination to image display device)
The said PET film was peeled and the adhesive layer was affixed on the liquid crystal cell which is an image display apparatus. Confirm that there is no biting of foreign matter, etc., and irradiate 3 J / cm ² ultraviolet rays with a gallium type UV lamp (manufactured by Fusion, V-bulb: bulb with emphasis on the region of 405 nm to 425 nm centered on 420 nm). went. The gel fraction after UV irradiation was 91% by weight.

Example 9
(Formation of polarizing plate C6 with adhesive layer)
With respect to 100 parts by weight of the solid content of the graft-modified acrylic polymer B1 solution obtained in the same manner as in Example 1, 2.0 parts by weight of 2-phenylimidazole as a thermosetting catalyst and trimethylolpropane adduct of xylylene diisocyanate (Mitsui Chemical Co., Ltd., D110N) 0.3 parts by weight, as a silane coupling agent, 0.1 part by weight of 3-glycidoxypropyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd., KBM403) is blended to prepare an adhesive solution. Prepared.

  On the one side of a 38 μm polyethylene terephthalate (PET) film (MRF-38, manufactured by Mitsubishi Plastics Co., Ltd.) obtained by subjecting the above adhesive solution to silicone release treatment, the thickness of the adhesive layer after drying is 25 μm. And dried at 120 ° C. for 3 minutes to form an adhesive layer having a thickness of 25 μm. Furthermore, it processed at 160 degreeC for 3 minute (s), Then, the adhesive agent layer was transcribe | transferred to the polarizing plate surface, and the polarizing plate C6 with an adhesive layer was produced. The gel fraction was 58% by weight before the heat treatment and 91% by weight after the heat treatment.

(Lamination to image display device)
The said PET film was peeled and the adhesive layer was affixed on the liquid crystal cell which is an image display apparatus.

(Comparative Example 1)
A sample was prepared in Example 1 without adding isocyanate.

(Comparative Example 2)
A sample was prepared in Example 1 without UV irradiation.

  The optical sheets with an adhesive layer obtained in the above Examples and Comparative Examples were evaluated.

<Measurement of weight average molecular weight>
The weight average molecular weight of the obtained (meth) acrylic polymer was measured by GPC (gel permeation chromatography). The sample used was a filtrate obtained by dissolving the sample in tetrahydrofuran to make a 0.1 wt% solution, which was allowed to stand overnight, and then filtered through a 0.45 μm membrane filter.
・ Analyzer: HLC-8120GPC manufactured by Tosoh Corporation
Column: manufactured by Tosoh Corporation, G7000H _XL + GMH _XL + GMH _XL
Column of low molecular weight _{substances: GM HR -H + GMH HR +} G2000MH HR
・ Column size: 7.8mmφ × 30cm each 90cm in total
・ Eluent: Tetrahydrofuran (concentration 0.1% by weight)
・ Flow rate: 0.8ml / min
・ Detector: Differential refractometer (RI)
-Column temperature: 40 ° C
・ Injection volume: 100 μl
Standard sample: Polystyrene Data processor: GPC-8020, manufactured by Tosoh

<Measurement of gel fraction>
The gel fraction of the adhesive layer before irradiation with active energy rays and after irradiation with active energy rays was measured by the following procedure. First, about 0.1 g of the adhesive layer was weighed (W1). Subsequently, this was wrapped in a microporous tetrafluoroethylene membrane, immersed in about 50 ml of ethyl acetate solution at 23 ° C. for 4 days, and then the soluble component was extracted. Thereafter, the adhesive layer was taken out together with the membrane, dried at 120 ° C. for 2 hours, and the adhesive weight (W2) remaining in the membrane was weighed. From these measured values, the gel fraction (% by weight) of the adhesive layer was determined according to the following formula.
Gel fraction (% by weight) = (W2 / W1) × 100

<Durability / humidification test>
Samples obtained in Examples and Comparative Examples were stored at 60 ° C. and 90% humidity, and charged for 500 hours. Thereafter, the state of the sample was visually observed and evaluated according to the following criteria.
○: There is no peeling or floating of the optical member in the image display device.
X: The optical member in an image display apparatus has peeling and floating.

<Durability / heat resistance test>
Samples obtained in Examples and Comparative Examples (liquid crystal cells with a polarizing plate with an adhesive layer attached) were placed in an 80 ° C. atmosphere for 500 hours. Thereafter, the state of the sample was visually observed and evaluated according to the following criteria.
○: There is no peeling or floating of the optical member in the image display device.
X: The optical member in an image display apparatus has peeling and floating.

<Processability>
The sample (polarizing plate with an adhesive layer before ultraviolet irradiation) obtained in Examples and Comparative Examples was punched out using a press. At that time, the case where the adhesive was not observed on the cutting blade was marked as ◯, and the case where the adhesive was taken or adhered was marked as x.

Each evaluation result is shown in Table 1.

Claims (15)

(Meth) acrylic polymer, a cyclic ether group-containing monomer and other strands 100 parts by weight modified acrylic graft polymer formed by graft polymerization comprising monomer; photopolymerization initiator 0.05 to 10 parts by weight or thermosetting catalyst An adhesive composition comprising 0.05 to 10 parts by weight of an imidazole compound ; and 0.01 to 5 parts by weight of an isocyanate crosslinking agent,
The adhesive composition in which the weight ratio of the cyclic ether group-containing monomer to the other monomer in the modified acrylic graft polymer is 90:10 to 10:90 . 100 parts by weight of a modified acrylic graft polymer obtained by graft polymerization of a chain containing a cyclic ether group-containing monomer and another monomer on a (meth) acrylic polymer; 0.05 to 10 parts by weight of a photopolymerization initiator; sensitizer The adhesive composition according to claim 1, comprising 0.05 to 5 parts by weight; and 0.01 to 5 parts by weight of an isocyanate crosslinking agent. The pressure-sensitive adhesive composition according to claim 1 or 2 , wherein the other monomer is an alkyl (meth) acrylate or alicyclic (meth) acrylate having 1 to 9 carbon atoms .   The adhesive composition according to any one of claims 1 to 3, wherein the photopolymerization initiator is a photocationic initiator that generates protons by photolysis. The imidazole compound as the thermosetting catalyst is 2-methylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, or 1-benzyl-2-methyl. The adhesive composition according to any one of claims 1 to 4, which is imidazole . The adhesive layer obtained from the adhesive composition in any one of Claim 1-5 . An optical member with an adhesive layer, wherein the adhesive layer according to claim 6 is formed on at least one side of the support. A cured adhesive layer obtained by irradiating or heat-treating active energy rays to the adhesive layer according to claim 6 . The cured adhesive layer according to claim 8 , wherein the gel fraction is 75 to 97% by weight. The gel fraction of the hardened adhesive layer, as compared with active energy ray irradiation before or before heat treatment of the adhesive layer gel fraction of 10 wt% or more higher than any of claims 8 or 9 The cured adhesive layer according to any one of the above.   The image display apparatus which has a hardening adhesive agent layer of any one of Claim 8-10. 100 parts by weight of a modified acrylic graft polymer obtained by graft polymerization of a chain containing a cyclic ether group-containing monomer on a (meth) acrylic polymer, 0.05 to 10 parts by weight of a photopolymerization initiator, A step of applying an adhesive composition containing 01 to 5 parts by weight to at least one surface of the optical member;
Irradiating the layer of the applied adhesive composition with active energy rays; and attaching the obtained cured adhesive layer to an image display device;
A method for manufacturing an image display device. 100 parts by weight of a modified acrylic graft polymer obtained by graft polymerization of a chain containing a cyclic ether group-containing monomer to a (meth) acrylic polymer, 0.05 to 10 parts by weight of a photopolymerization initiator, 0.05 to Applying an adhesive composition containing 5 parts by weight and 0.01 to 5 parts by weight of an isocyanate-based crosslinking agent to at least one surface of the optical member;
A step of attaching the applied adhesive composition layer to an image display device; and a step of irradiating active energy rays from the optical member side;
A method for manufacturing an image display device. The method for producing an image display device according to claim 12 , wherein the adhesive layer is affixed to the image display device within a period of 1 second to 60 minutes after irradiation with the active energy ray. 100 parts by weight of a modified acrylic graft polymer obtained by graft-polymerizing a chain containing a cyclic ether group-containing monomer to a (meth) acrylic polymer, 0.05 to 10 parts by weight of an imidazole compound as a thermosetting catalyst, and isocyanate crosslinking agent adhesive composition comprising 0.01 to 5 parts by weight, was coated on a support, further heat treatment to cure the adhesive layer obtained, bonded to at least one surface of the optical member Attaching step; and
Peeling the support and attaching the cured adhesive layer to the image display device;
A method for manufacturing an image display device.