JP5687420B2 - Adhesive composition for solvent-based optical member, adhesive layer, and optical member with adhesive - Google Patents

Description

  The present invention provides a pressure-sensitive adhesive composition for a solvent-based optical member that is excellent in re-peelability and adhesion durability, a pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition, and such a pressure-sensitive adhesive layer as at least an optical member. It is related with the optical member with an adhesive which has on one side.

  In recent years, liquid crystal display devices are widely used and not only for mobile phones and personal computers, but also for television applications. An optical member used for the liquid crystal display device or the like, such as a polarizing plate or a retardation plate, is attached to the liquid crystal cell using an adhesive.

  When an optical member is bonded to a liquid crystal cell, the optical member may be peeled from the liquid crystal panel and reused even if the bonding position is wrong or a foreign object is caught in the bonding surface. . When the optical member is peeled from the liquid crystal panel, it does not become an adhesive state that changes the gap of the liquid crystal cell or breaks the optical member, that is, the removability (reworkability) that can easily peel the optical member. Needed. However, when the durability of the pressure-sensitive adhesive for optical members is emphasized and the adhesiveness is simply improved, the reworkability is deteriorated.

  As the pressure-sensitive adhesive for optical members, an acrylic pressure-sensitive adhesive is generally used because of its advantages such as weather resistance and transparency. When forming an adhesive layer using an acrylic adhesive, it is usual to use a high molecular weight polymer.

For example, an acrylic polymer pressure-sensitive adhesive for optical members having a weight average molecular weight of 100,000 or less is 15% by weight or less, a component of 1,000,000 or more is 10% by weight or more, and the weight average molecular weight is 50 A weight average molecular weight of 100 having an acrylic polymer with an Mw / Mn of 4 or less and an epoxy group-containing silane coupling agent for an optical member (Patent Document 2), a carboxyl group, a hydroxyl group, and an amide group as essential components Ten to two million optical member pressure-sensitive adhesives (Patent Document 3) have been proposed. Furthermore, an adhesive for optical members (Patent Document 4) is disclosed in which the gel fraction of the acrylic polymer is 50 to 90%, and the weight average molecular weight of the uncrosslinked component at that time is 100,000 or more.

However, when the weight average molecular weight of the acrylic polymer is 1 million or more, the viscosity of the polymer solution becomes high. Therefore, the concentration that can be applied to various support films is about 20% by weight. There is a problem that the coated surface becomes rough at the time of coating, which causes a problem that the amount of solvent used increases. On the other hand, if the polymer has a low molecular weight, the concentration can be increased to 40% by weight, but the durability is not sufficient. In Patent Document 1 and Patent Document 4, the solid concentration can be 40% by weight and 20% by weight, respectively, but there is a problem that the process of removing low molecular weight components in the polymer is complicated.

JP-A 64-66283 Japanese Patent Laid-Open No. 7-20314 JP-A-9-59580 JP-A-10-46125

  The present invention is excellent in removability and exhibits excellent durability that does not cause foaming, floating, and peeling even with large expansion and contraction of an optical member, has a smooth coating surface, and is a solvent used in the process. It aims at providing the adhesive composition for solvent type optical members which can reduce the usage-amount.

  Another object of the present invention is to provide a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition for solvent-based optical members and a pressure-sensitive adhesive optical member having the pressure-sensitive adhesive layer.

  As a result of intensive studies to solve the above problems, the present inventors have adjusted the amount of the hydroxyl group-containing monomer in the polymer even if the molecular weight of the acrylic polymer is relatively small, It has been found that by using a radical generator, both excellent durability and ease of peeling can be achieved, and the present invention has been completed.

That is, the present invention is a gel permeation obtained by copolymerizing, as a monomer component, 50% by weight or more of n-butyl acrylate, 0.1 to 2% by weight of a hydroxyl group-containing monomer, and 0 to 49.8% by weight of other monomers. Acrylic polymer having a weight average molecular weight of 500,000 to 1,000,000 according to Aation Chromatography; A pressure-sensitive adhesive composition for optical members comprising an isocyanate-based crosslinking agent, and 0.01 to 1 part by weight of a silane coupling agent; and 75% by weight or less of a solvent,
It is related with the adhesive composition for solvent type | system | group optical members whose viscosity in B-type viscometer 100rpm at 23 degreeC is 8 Pa * s or less.

In the above-mentioned pressure-sensitive adhesive composition for solvent-based optical members, the hydroxyl group-containing monomer is CH ₂ ═C (R ¹ ) COOC _n H _2n OH (where R ¹ is hydrogen or a methyl group, n is 4 to 6) It may be a hydroxyl group-containing (meth) acrylate represented by:

In the above-mentioned pressure-sensitive adhesive composition for solvent-based optical members, the relationship between the weight percent (a) of the hydroxyl group-containing monomer in the acrylic polymer and the number average molecular weight (b) of the acrylic polymer is 1 <a × b / 10 ⁴ <20.

In the adhesive composition for solvent-based optical members, the radical generator may be an organic peroxide.

In the above-mentioned pressure-sensitive adhesive composition for solvent-based optical members, the radical generator may be a compound that generates radicals upon irradiation with active energy rays.

The present invention also relates to a pressure-sensitive adhesive layer obtained from any one of the above-mentioned pressure-sensitive adhesive compositions for solvent-based optical members.

In the pressure-sensitive adhesive layer, the gel fraction may be 40 to 90% by weight.

In the pressure-sensitive adhesive layer, the solvent-soluble component may have a weight average molecular weight of 100,000 or more.

The present invention also relates to an optical member with a pressure-sensitive adhesive in which any one of the pressure-sensitive adhesive layers is formed on at least one side of the optical member.

In the optical member with an adhesive, the optical member may be a material having an optical function such as a polarizing plate, a retardation plate, or an elliptically polarizing plate.

  The pressure-sensitive adhesive composition for solvent-based optical members of the present invention has properties that the amount of solvent used can be reduced and coating properties are excellent. And, it is set to have a predetermined gel fraction and a predetermined molecular weight of the uncrosslinked polymer by coating, drying, and crosslinking, and after attaching the optical member to the liquid crystal cell under high temperature and high humidity conditions Even when stored, high durability that does not cause peeling or foaming is exhibited, and even when the optical member is peeled off and the liquid crystal cell is reused, no increase in adhesive force is observed, and the reworkability is excellent.

  The pressure-sensitive adhesive composition for solvent-based optical members of the present invention is obtained by copolymerizing 50% by weight or more of n-butyl acrylate, 0.1 to 2% by weight of a hydroxyl group-containing monomer, and 0 to 49.8% by weight of other monomers. An acrylic polymer having a weight average molecular weight of 500,000 to 1,000,000 by gel permeation chromatography is included as a base polymer.

  In the present invention, n-butyl acrylate is 50% by weight or more, may be 50.1% by weight or more, preferably 60% by weight or more, based on all monomer components of the acrylic polymer. Preferably, it is 72 weight% or more. Further, n-butyl acrylate is 99.9% by weight or less, preferably 98% by weight or less, and more preferably 85% by weight or less, based on all monomer components of the acrylic polymer. .

  In addition, the (meth) acrylic polymer of the present invention includes a hydroxyl group-containing monomer. The hydroxyl group-containing monomer preferably includes a hydroxyl group-containing monomer containing an alkyl group having 4 to 6 carbon atoms and at least one hydroxyl group. That is, this monomer is a monomer containing a hydroxyalkyl group having 4 to 6 carbon atoms and one or more hydroxyl groups. Here, the hydroxyl group is preferably present at the terminal of the alkyl group. The number of carbon atoms of the alkyl group is preferably 4-6. If it is this range, it will become possible to achieve a preferable gel fraction and the adhesive layer excellent in workability can be created.

As such a monomer, those 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, 2-hydroxypropyl (meth) acrylate, 2-hydroxypentyl (meth) acrylate, 2-hydroxyhexyl (meth) acrylate, 3-hydroxy Hydroxyalkyl (meth) acrylates such as propyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, etc .; 4-hydroxymethylcyclohexyl (meth) acrylate, 4-hydroxybutyl Examples include vinyl ether. Among these, it is preferable to use acrylic acid esters such as 4-hydroxybutyl acrylate, 5-hydroxypentyl acrylate, and 6-hydroxyhexyl acrylate.

The hydroxyl group-containing monomer is used in a proportion of 0.1 to 2% by weight with respect to the total amount of monomer components forming the (meth) acrylic polymer. The ratio of the hydroxyl group-containing monomer is preferably 0.2 to 1.5% by weight.

  In addition to the monomer, other monomers can be used as the monomer component for forming the (meth) acrylic polymer. The total amount of other monomers is a ratio of 0 to 49.8% by weight, preferably 5 to 30% by weight, based on the total monomers constituting the polymer. Examples of such other monomers include n-butyl methacrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, Hexyl (meth) acrylate, heptyl (meth) acrylate, isoamyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meta ) Acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, Somyristyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, phenoxyethyl (meth) acrylate, isobornyl (meth) acrylate, etc. It is done.

Furthermore, it is also preferable to use a carboxyl group-containing monomer. As the carboxyl group-containing monomer, an unsaturated carboxylic acid-containing 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 is used without particular limitation. be able to. 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. Of these, acrylic acid and methacrylic acid are preferably used.

  When used, the carboxyl group-containing monomer is preferably used in a proportion of up to 7% by weight, more preferably in a proportion of up to 5% by weight, based on the total amount of monomer components forming the acrylic polymer. . In particular, there is no lower limit, but the amount used is 0.05% by weight or more, preferably 0.1% by weight or more.

  Furthermore, you may use another copolymerization monomer individually or in combination in the range which does not impair the objective of this invention. Examples of the other copolymerization monomer include aromatic ring-containing monomers having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having an aromatic ring. . Specific examples of the aromatic ring-containing monomer include phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, phenol ethylene oxide modified (meth) acrylate, 2-naphthoethyl (meth) acrylate, 2- (4-methoxy-1- And naphthoxy) ethyl (meth) acrylate, phenoxypropyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, and polystyryl (meth) acrylate.

  In addition, 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-2-methylpropane sulfonic acid, (meth) Sulfonic acid group-containing monomers such as acrylamide propanesulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid; phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate; methoxyethyl (meth) acrylate, ( (Meth) acrylic acid alkoxyalkyl monomers such as ethoxyethyl (meth) acrylate;

  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, may be used, such as vinyl ether monomers.

  Furthermore, the silane type monomer containing a silicon atom etc. are mention | raise | lifted. 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 weight average molecular weight of the acrylic polymer of the present invention needs to be 500,000 or more, preferably 650,000 or more. When the weight average molecular weight is less than 500,000, the durability of the pressure-sensitive adhesive layer becomes poor, or the cohesive force of the pressure-sensitive adhesive layer becomes small and adhesive residue tends to occur. On the other hand, the weight average molecular weight must be 1,000,000 or less, and preferably 950,000 or less. When it is out of the range of 500,000 or more and 1,000,000 or less, the bonding property and the adhesive strength are lowered. Furthermore, the pressure-sensitive adhesive composition may become too viscous in a solution system, and coating may be difficult. The weight average molecular weight is a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.

For production of such an acrylic polymer, known production methods such as various radical polymerizations such as solution polymerization and bulk polymerization can be appropriately selected. The obtained acrylic polymer may be any of a random copolymer, a block copolymer, a graft copolymer, and the like.

  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 8 to 30 hours.

  A polymerization initiator, a chain transfer agent, 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 Azo initiators such as' -azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (manufactured by Wako Pure Chemical Industries, Ltd., VA-057), di (2-ethylhexyl) peroxydicarbonate, Di (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxyneo Canoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexa Noate, di (4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butylperoxyisobutyrate, 1,1-di (t-hexylperoxy) cyclohexane, t-butyl hydroperoxide, etc. However, it is not limited to these.

  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 0.01 to 0.2 parts by weight, more preferably about 0.08 to 0.175 parts by weight.

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

When adjusting the molecular weight and the hydroxyl group-containing monomer amount, the relationship between the hydroxyl group-containing monomer amount (a) and the number average molecular weight (b) of the acrylic polymer is 1 <a × b / 10 ⁴ <20, preferably Is in the range of 2 <a × b / 10 ⁴ <15, more preferably 3 <a × b / 10 ⁴ <15.

In the pressure-sensitive adhesive composition for solvent-based optical members of the present invention, 0.05 to 2 parts by weight of a radical generator and 0.05 to 2 parts by weight of an isocyanate-based cross-linkage with respect to 100 parts by weight of such a base polymer. And a pressure-sensitive adhesive composition containing 0.01 to 1 part by weight of a silane coupling agent in an amount of 25% by weight or more and a solvent of 75% by weight or less. , 8 Pa · s or less.

Such a solvent-based optical member pressure-sensitive adhesive composition has a gel fraction after the crosslinking reaction of 40 to 90%, and the solvent-soluble component after the crosslinking reaction has a weight average molecular weight of 100,000 or more. Is preferred.

Crosslinking between polymers due to hydrogen abstraction by radical generators works to extend the main chain, and crosslinks by hydroxyl groups in the polymer by isocyanate-based crosslinking agents work, and the weight average molecular weight of solvent-soluble components after crosslinking reaction is 100,000 or more Thus, the durability of the obtained adhesive is considered to be good.

The radical generator used in the present invention is not particularly limited as long as it is a compound that generates radicals by heating or irradiation with active energy rays, and examples thereof include peroxides.

As the peroxide, any radical active species can be used as long as it generates radical active species by heating to advance the crosslinking of the base polymer of the pressure-sensitive adhesive composition. However, in consideration of workability and stability, 1 minute can be used. It is preferable to use a peroxide having a half-life temperature of 80 ° C to 160 ° C, and it is 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) ".

  One of the peroxides may be used alone, or a mixture of two or more may be used. When crosslinking is performed using a peroxide, the amount of decomposition of the peroxide is 50% or more, preferably 75% or more in order to generate radicals effectively without a peroxide remaining and to cause a crosslinking reaction. The setting of the crosslinking treatment temperature and time is a guideline. If the amount of peroxide decomposition is small, the amount of remaining peroxide increases and a crosslinking reaction over time occurs, which is not preferable. Specifically, for example, when the crosslinking treatment temperature is 1 minute half-life temperature, the decomposition amount is 50% in 1 minute and 75% in 2 minutes, and it is necessary to heat treatment for 1 minute or more. If the peroxide half-life time is 30 seconds, a crosslinking treatment of 30 seconds or more is required. If the peroxide half-life time at the crosslinking treatment temperature is 5 minutes, a crosslinking treatment of 5 minutes or more is required. It becomes. In this way, the crosslinking treatment temperature and time are proportionally calculated and adjusted from the half-life time assuming that the peroxide is temporarily proportional, depending on the peroxide used. It is necessary to heat-treat. Of course, the temperature at the time of drying may be used as it is, or may be processed after drying. The treatment time is set in consideration of productivity and workability, but 0.2 to 20 minutes, preferably 0.5 to 10 minutes are used. Note that the amount of peroxide decomposition remaining after the reaction treatment is used. As a measuring method, for example, it can be measured by HPLC (high performance liquid chromatography).

  More specifically, for example, about 0.2 g of the pressure-sensitive adhesive composition after the reaction treatment is taken out, immersed in 10 ml of ethyl acetate, extracted by shaking at 25 ° C. and 120 rpm for 3 hours with a shaker, and then at room temperature. Leave 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.

  In the case of using a peroxide, 0.05 parts by weight or more, preferably 0.07 parts by weight or more, and 2 parts by weight or less, preferably 1 part by weight or less is used with respect to 100 parts by weight of the base polymer. The If it is this range, a crosslinking reaction is sufficient, it is excellent in durability, it does not become excessive crosslinking, and it can obtain the composition excellent in adhesiveness, and is preferable.

A photocrosslinking agent can also be used as the radical generator. A photocrosslinking agent is a crosslinking agent that is capable of advancing a crosslinking reaction under the action of light such as sunlight; laser light; radiated light (electromagnetic waves) such as infrared rays, visible rays, ultraviolet rays, and X-rays. Hydroxy ketones, benzyl dimethyl ketals, amino ketones, acylphosphine oxides, benzophenones, trichloromethyl group-containing triazine derivatives and the like can be used. Examples of triazine derivatives containing trichloromethyl groups include 2- (p-methoxyphenyl) -4,6-bis- (trichloromethyl) -s-triazine, 2-phenyl-4,6-bis- (trichloromethyl) -s. -Triazine, 2- (4'-methoxy-1'-naphthyl) -4,6-bis- (trichloromethyl) -s-triazine, 2,4-trichloromethyl- (4'-methoxyphenyl) -6-triazine 2,4-trichloromethyl- (4′-methoxynaphthyl) -6-triazine, 2,4-trichloromethyl- (piperonyl) -6-triazine, 2,4-trichloromethyl- (4′-methoxystyryl)- 6-triazine is mentioned. Further, 2-hydroxy-2-methyl- [4- (1-methylvinyl) phenyl] propanol oligomer, oligomer obtained by polymerizing acrylated benzophenone, 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy- 2-methyl-1-propan-1-one, photocleavable α-hydroxyphenyl ketone (for example, an oligomer such as an oligomer obtained by polymerizing a reaction product of a primary hydroxyl group with 2-isocyanatoethyl methacrylate under the trade name Irgacure 2959 (Ciba Specialty Chemicals)) These oligomer-type photocrosslinking agents preferably have a molecular weight of up to about 50,000, more preferably 1000 or more and 50,000 or less.If the molecular weight exceeds this, an acrylic polymer is used. May become incompatible.

Of these, when a polyfunctional photocrosslinking agent having a plurality of radical generation points in the molecule is used, it can be used alone. It is also possible to use a polyfunctional type and a monofunctional type in combination.

It is preferable to use a photosensitizer such as an acetophenone compound, a phosphine oxide compound, and an imidazole compound together with the photocrosslinking agent. By using a photosensitizer, it is possible to crosslink efficiently.

Examples of acetophenone compounds include 4-diethylaminoacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-4′-morpholinobutyrophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2, Examples include 2-dimethoxy-1,2-diphenylethane-1-one.

Examples of phosphine oxide compounds include phenylbis (2,4,6-trimethylbenzoyl) -phosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and 2,4,6-trimethylbenzoylphenylethoxyphosphine. Examples include oxides.

Examples of the imidazole compound include 2-p-dimethylphenyl-4-phenyl-imidazole, 4,5-bis-p-biphenyl-imidazole, 2,2′-bis (2-methylphenyl) -4,4 ′, 5. , 5′-tetraphenyl-1,2′-biimidazole, 2,2′-bis (2-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2′-biimidazole, 2, Examples include 2'-bis (2,4-dichlorophenyl) -4,4 ', 5,5'-tetraphenyl-1,2'-biimidazole.

The content of the photocrosslinking agent as a radical generator is 0.05 parts by weight or more, preferably 0.07 parts by weight or more, preferably 2 parts by weight or less, preferably 100 parts by weight of the base polymer. Is 1 part by weight or less. If it is this range, a crosslinking reaction is sufficient, it is excellent in durability, it does not become excessive crosslinking, and it can obtain the composition excellent in adhesiveness, and is preferable.

  The isocyanate-based crosslinking agent used as a crosslinking agent is a compound having two or more isocyanate groups (including isocyanate-regenerating functional groups in which isocyanate groups are temporarily protected by blocking agents or quantification) in one molecule. Say.

  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. In applications where transparency is required, aliphatic and alicyclic isocyanates are preferably used instead of aromatic isocyanate compounds.

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, it is preferable to contain 0.05-2 weight part of the said isocyanate compound crosslinking agent, and it is more preferable to contain 0.07-1 weight part. It can be appropriately contained in consideration of cohesive force and prevention of peeling in a durability test.

  The silane coupling agent contained in the pressure-sensitive adhesive composition for optical members of the present invention contains a silane compound having a functional group. Examples of the silane compound include epoxy group-containing silane couplings such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane. Agent, 3-aminopropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine, N-phenylamino Amino group-containing silane coupling agents such as propyltrimethoxysilane, (meth) acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane, 3-isocyanatopropyltriethoxy Silane etc. And an isocyanate group-containing silane coupling agent.

  The silane compound may be used alone or in combination of two or more, but the total content is 0.01 to 1 weight with respect to 100 parts by weight of the acrylic polymer. Parts, preferably 0.02 to 0.6 parts by weight. If it is the use of this range, a composition will have both adhesive force and removability, and it is preferable.

  The pressure-sensitive adhesive composition thus formulated is adjusted to a solid content of 25% by weight or more and a solvent of 75% by weight or less. Preferably, the solid content is 25 to 60% by weight and the solvent is 40 to 75% by weight. More preferably, the solid content is 30% by weight to 50% by weight and the solvent is 50% by weight to 70% by weight. Although the solvent in this case is not limited, ethyl acetate, toluene and the like used for the polymerization of the base polymer are preferably used. Furthermore, the viscosity is 8 Pa · s or less, preferably 6 Pa · s or less as measured with a B-type viscometer 100 rpm at 23 ° C. There is no particular lower limit, but 1 Pa · s or more is preferable. That is, the composition of the present invention is in the form of a solution. By having such characteristics, it is possible to perform coating stably and without roughening the coating surface on a roll coater such as a comma coater or reverse coater that is normally used, and the amount of solvent used is also reduced. be able to.

  The pressure-sensitive adhesive layer is formed by the crosslinking agent. In forming the pressure-sensitive adhesive layer, it is necessary to adjust the addition amount of the entire crosslinking agent and sufficiently consider the influence of the crosslinking treatment temperature and the crosslinking treatment time.

  In producing the pressure-sensitive adhesive layer, the gel fraction of the crosslinked pressure-sensitive adhesive layer is preferably adjusted to be 40 to 90% by weight, more preferably 47 to 85% by weight, and still more preferably 50 to 80% by weight.

  The predetermined gel fraction can be adjusted by adjusting the addition amount of the isocyanate-based crosslinking agent and the photocrosslinking agent and considering the influence of the light irradiation amount.

Moreover, the weight average molecular weight Mw of the solvent soluble part after a crosslinking reaction is 100,000 or more, Preferably it is 120,000 or more, More preferably, it is 150,000 or more. When the Mw is 100,000 or more, the durability of the pressure-sensitive adhesive layer becomes good.

  Furthermore, the pressure-sensitive adhesive composition of the present invention may contain other known additives, such as powders such as colorants and pigments, dyes, surfactants, plasticizers, tackifiers, Use 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 be added appropriately depending on the application.

  The optical member with pressure-sensitive adhesive of the present invention is obtained by forming a pressure-sensitive adhesive layer with the pressure-sensitive adhesive on at least one surface of the optical member.

  As a method for forming the pressure-sensitive adhesive layer, for example, the pressure-sensitive adhesive composition is applied to a release-treated separator, and the polymerization solvent is dried and removed to form a pressure-sensitive adhesive layer, which is then transferred to an optical member. It is produced by a method or a method of applying the pressure-sensitive adhesive composition to an optical member, drying and removing a polymerization solvent and the like, and performing a crosslinking treatment to form a pressure-sensitive adhesive layer on the optical member. In applying the pressure-sensitive adhesive, one or more solvents other than the polymerization solvent may be added as appropriate.

A silicone release liner is preferably used as the release-treated separator. In the step of applying the adhesive composition of the present invention on such a liner and drying to form a pressure-sensitive adhesive layer, a method for drying the pressure-sensitive adhesive is appropriately employed depending on the purpose. obtain. 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.

  In addition, the pressure-sensitive adhesive layer can be formed after forming an anchor layer on the surface of the optical member or performing various easy adhesion treatments such as corona treatment and plasma treatment. Moreover, you may perform an easily bonding process on the surface of an adhesive layer.

  Various methods are used as a method of forming the pressure-sensitive 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 in particular of an adhesive layer is not restrict | limited, For example, it is about 2-500 micrometers. Preferably, it is 5-100 micrometers, More preferably, it is 5-50 micrometers.

The emitted light used in the crosslinking / curing treatment step of the present invention is not particularly limited, and examples thereof include infrared rays, visible rays, ultraviolet rays, X-rays, and other electron beams. Among these, ultraviolet rays are particularly preferable. When the pressure-sensitive adhesive composition of the present invention is used, there is no need to use an inert gas atmosphere or to cover the coating film with an oxygen-blocking cover film when irradiating with radiation, and work efficiency Excellent.

For example, when using ultraviolet rays, can be appropriately determined by the type of polymer and photocrosslinking agent used is generally at 20mJ / ^{cm 2} ~10J / ^cm 2, preferably about 1J / ^cm 2 ~5J / ^{cm 2} . UV irradiation is low pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, metal halide lamp, chemical lamp, black light lamp, mercury-xenon lamp, excimer lamp, short arc lamp, helium / cadmium laser, argon laser, excimer laser, Sunlight or the like can be used as a light irradiation light source, and among them, it is preferable to use a low-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a metal halide lamp, or the like.

Moreover, although the wavelength of an ultraviolet-ray can be suitably selected according to the grade of required bridge | crosslinking, it is preferable that it is 200-500 nm, it is more preferable that it is 250-480 nm, and it is 300-480 nm. Is more preferable. The irradiation amount of these ultraviolet rays is UVA (320 to 390 nm), UVB (280 to 320 nm), UVC (250 to 260 nm), and UVV (395 to 445 nm) measured by “UV Power Pack” (manufactured by EIT). Refers to the total amount of light.

  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.

  When the pressure-sensitive adhesive layer is exposed, the pressure-sensitive adhesive layer may be protected with a sheet (separator) that has been subjected to a release treatment until practical use.

  Examples of the constituent material of the separator include, for example, plastic 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. A thin film can be used, but a plastic film is preferably used because of its excellent surface smoothness.

  The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. For example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, and a vinyl chloride co-polymer are used. Examples thereof include a polymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

  The thickness of the separator is usually about 5 to 200 μm, preferably about 5 to 100 μm. For the separator, if necessary, mold release and antifouling treatment with a silicone type, fluorine type, long chain alkyl type or fatty acid amide type 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, when the surface of the separator is appropriately subjected to a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment, the peelability from the pressure-sensitive adhesive layer can be further improved.

  In addition, the sheet | seat which carried out the peeling process used in preparation of said adhesive type optical member can be used as a separator of an adhesive type optical member as it is, and can simplify in the surface of a process.

  As the optical member, those used for forming an image display device such as a liquid crystal display device are used, and the type thereof is not particularly limited. For example, the optical member includes a polarizing plate. A polarizing plate having a transparent protective film on one or both sides of a polarizer is generally used.

  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 material 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 prepared, for example, by immersing 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 such as potassium iodide 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 dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. 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 such as boric acid or potassium iodide or in a water bath.

  Examples of the optical member used in the pressure-sensitive adhesive optical member of the present invention include a polarizing plate. A polarizing plate having a transparent protective film on one or both sides of a polarizer is generally used.

  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 material 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 prepared, for example, by immersing 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 such as potassium iodide 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 dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. 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 such as boric acid or potassium iodide or in a water bath.

  As a material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic Examples thereof include polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. A transparent protective film is bonded to one side of the polarizer by an adhesive layer. On the other side, as a transparent protective film, (meth) acrylic, urethane-based, acrylurethane-based, epoxy-based, silicone A thermosetting resin such as a system or an ultraviolet curable resin can be used. One or more kinds of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. . When content of the said thermoplastic resin in a transparent protective film is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

  Moreover, as a transparent protective film, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007), for example, (A) thermoplastic resin which has a substituted and / or unsubstituted imide group in a side chain, ( B) Resin compositions containing thermoplastic resins having substituted and / or unsubstituted phenyl and nitrile groups in the side chains. A specific example is a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used. Since these films have a small phase difference and a small photoelastic coefficient, problems such as unevenness due to the distortion of the polarizing plate can be eliminated, and since the moisture permeability is small, the humidification durability is excellent.

  Although the thickness of a transparent 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 layer property. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable. The transparent protective film is particularly suitable when the thickness is 5 to 150 μm.

  In addition, when providing a transparent protective film on both sides of a polarizer, the protective film which consists of the same polymer material may be used by the front and back, and the protective film which consists of a different polymer material etc. may be used.

  As the transparent protective film of the present invention, it is preferable to use at least one selected from cellulose resin, polycarbonate resin, cyclic polyolefin resin, and (meth) acrylic resin.

  Cellulose resin is an ester of cellulose and fatty acid. Specific examples of the cellulose ester resin include triacetyl cellulose, diacetyl cellulose, tripropionyl cellulose, dipropionyl cellulose and the like. Among these, triacetyl cellulose is particularly preferable. Many products of triacetylcellulose are commercially available, which is advantageous in terms of availability and cost. Examples of commercial products of triacetyl cellulose include trade names “UV-50”, “UV-80”, “SH-80”, “TD-80U”, “TD-TAC”, “UZ” manufactured by Fuji Film Co., Ltd. -TAC "and" KC series "manufactured by Konica. In general, these triacetyl celluloses have an in-plane retardation (Re) of almost zero, but a thickness direction retardation (Rth) of about 60 nm.

  In addition, the cellulose resin film with a small thickness direction phase difference is obtained by processing the said cellulose resin, for example. For example, a base film such as polyethylene terephthalate, polypropylene, and stainless steel coated with a solvent such as cyclopentanone and methyl ethyl ketone is bonded to a general cellulose film and dried by heating (for example, at 80 to 150 ° C. for about 3 to 10 minutes). ) And then peeling the base film; a solution obtained by dissolving norbornene resin, (meth) acrylic resin, etc. in a solvent such as cyclopentanone, methyl ethyl ketone, etc. is applied to a general cellulose resin film and dried by heating ( For example, a method of peeling the coated film after 80 to 150 ° C. for about 3 to 10 minutes is mentioned.

  Moreover, as a cellulose resin film with a small thickness direction retardation, the fatty acid cellulose resin film which controlled the fat substitution degree can be used. Generally used triacetyl cellulose has an acetic acid substitution degree of about 2.8. Preferably, the Rth can be reduced by controlling the acetic acid substitution degree to 1.8 to 2.7. Rth can be controlled to be small by adding a plasticizer such as dibutyl phthalate, p-toluenesulfonanilide, acetyltriethyl citrate to the fatty acid-substituted cellulose resin. The addition amount of the plasticizer is preferably 40 parts by weight or less, more preferably 1 to 20 parts by weight, and still more preferably 1 to 15 parts by weight with respect to 100 parts by weight of the fatty acid cellulose resin.

  Specific examples of the cyclic polyolefin resin are preferably norbornene resins. The cyclic olefin-based resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers), And graft polymers obtained by modifying them with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers.

  Various products are commercially available as the cyclic polyolefin resin. As specific examples, trade names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, product names “ARTON” manufactured by JSR Corporation, “TOPAS” manufactured by TICONA, and product names manufactured by Mitsui Chemicals, Inc. “APEL”.

  The (meth) acrylic resin preferably has a Tg (glass transition temperature) of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. When Tg is 115 ° C. or higher, the polarizing plate can be excellent in durability. Although the upper limit of Tg of the (meth) acrylic resin is not particularly limited, it is preferably 170 ° C. or less from the viewpoint of moldability. From (meth) acrylic resin, a film having in-plane retardation (Re) and thickness direction retardation (Rth) of almost zero can be obtained.

  As the (meth) acrylic resin, any appropriate (meth) acrylic resin can be adopted as long as the effects of the present invention are not impaired. For example, poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester- (Meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, Methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.). Preferably, poly (meth) acrylate C1-6 alkyl such as poly (meth) acrylate methyl is used. More preferred is a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight).

  Specific examples of (meth) acrylic resins include (meth) acrylic resins having a ring structure in the molecule described in, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and JP-A-2004-70296. And a high Tg (meth) acrylic resin system obtained by intramolecular crosslinking or intramolecular cyclization reaction.

  As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure can also be used. It is because it has high mechanical strength by high heat resistance, high transparency, and biaxial stretching.

  Examples of the (meth) acrylic resin having a lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. Examples thereof include (meth) acrylic resins having a lactone ring structure described in Japanese Patent No. 146084.

  The (meth) acrylic resin having a lactone ring structure preferably has a ring pseudo structure represented by the following general formula (Formula 6).

^Wherein, R 1, ^{R 2} and ^{R 3} each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  The content ratio of the lactone ring structure represented by the general formula (Formula 6) in the structure of the (meth) acrylic resin having a lactone ring structure is preferably 5 to 90% by weight, more preferably 10 to 70% by weight, More preferably, it is 10 to 60% by weight, and particularly preferably 10 to 50% by weight. When the content of the lactone ring structure represented by the general formula (Chem. 6) in the structure of the (meth) acrylic resin having a lactone ring structure is less than 5% by weight, the heat resistance, solvent resistance, and surface hardness are low. May be insufficient. When the content ratio of the lactone ring structure represented by the general formula (Chemical Formula 6) in the structure of the (meth) acrylic resin having a lactone ring structure is more than 90% by weight, molding processability may be poor.

  The (meth) acrylic resin having a lactone ring structure has a mass average molecular weight (sometimes referred to as a weight average molecular weight) of preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, and particularly preferably. Is 50,000 to 500,000. If the mass average molecular weight is out of the above range, it is not preferable from the viewpoint of molding processability.

  The (meth) acrylic resin having a lactone ring structure preferably has a Tg of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. Since Tg is 115 ° C. or higher, for example, when incorporated into a polarizing plate as a transparent protective film, it has excellent durability. Although the upper limit of Tg of the (meth) acrylic resin having the lactone ring structure is not particularly limited, it is preferably 170 ° C. or less from the viewpoint of moldability and the like.

  The (meth) acrylic resin having a lactone ring structure is preferably as the total light transmittance of a molded product obtained by injection molding measured by a method according to ASTM-D-1003 is higher, preferably 85. % Or more, more preferably 88% or more, and still more preferably 90% or more. The total light transmittance is a measure of transparency. If the total light transmittance is less than 85%, the transparency may be lowered.

  The transparent protective film may be subjected to surface modification treatment in order to improve adhesiveness with the polarizer before applying the adhesive. Specific examples of the treatment include corona treatment, plasma treatment, flame treatment, ozone treatment, primer treatment, glow treatment, saponification treatment, and treatment with a coupling agent. Further, an antistatic layer can be appropriately formed.

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

  In addition, as an optical film, for example, for formation of a liquid crystal display device such as a reflection plate, an anti-transmission plate, the retardation plate (including wavelength plates such as 1/2 and 1/4), a visual compensation film, and a brightness enhancement film. The optical layer which may be used is mentioned. These can be used alone as an optical film, or can be laminated on the polarizing plate for practical use and used as one layer or two or more layers.

  The pressure-sensitive adhesive optical film of the present invention can be preferably used for forming various image display devices such as liquid crystal display devices. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, an adhesive optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no particular limitation except that an adhesive optical film is used. As the liquid crystal cell, any type such as a TN type, STN type, π type, VA type, IPS type, or the like can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which an adhesive optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the optical film according to the present invention can be installed on one side or both sides of the liquid crystal cell. When optical films are provided on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  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, even if there is no description in particular, the part and% in each example are based on a weight. The room temperature standing conditions not specifically defined below are all 23 ° C. and 65% RH (1 hour or 1 week). Evaluation items in Examples and the like were measured as follows.

<Measurement of weight average molecular weight>
The weight average molecular weight of the obtained acrylic polymer was measured by GPC (gel permeation chromatography). The sample was prepared by dissolving the sample in dimethylformamide to give a 0.1% by weight 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: G7000HXL + GMHXL + GMHXL, manufactured by Tosoh Corporation
・ 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

<Measurement of gel fraction>
The gel fraction was determined by immersing the dried and cross-linked adhesive (initial weight W ₁ ) in an ethyl acetate solution and allowing it to stand at room temperature for 1 week, then removing insolubles and drying (W ₂ ) Was measured and determined as follows.
(W ₂ / W ₁ ) × 100 (% by weight)

<Measurement of weight average molecular weight of sol>
The ethyl acetate solution after taking out the insoluble matter was dried under reduced pressure at 30 ° C., and the residue was dissolved in dimethylformamide to obtain a 0.1% solution. After standing overnight, a 0.45 μm membrane filter was obtained. The filtrate filtered through was used.
・ Analyzer: HLC-8120GPC manufactured by Tosoh Corporation
Column: G7000HXL + GMHXL + GMHXL, manufactured by Tosoh Corporation
・ 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

(Creation of polarizing plate)
A polyvinyl alcohol film (thickness 80 μm) is stretched 5 times the original length in an aqueous iodine solution at 40 ° C., and then the polyvinyl alcohol film is pulled up from the aqueous iodine solution and dried at 50 ° C. for 4 minutes to obtain a polarizer. Got. A polarizing plate was prepared by bonding a triacetyl cellulose film as a transparent protective film on both sides of this polarizer using a polyvinyl alcohol type adhesive.

Example 1
(Preparation of acrylic polymer)
In a four-necked flask equipped with a stirring blade, thermometer, nitrogen gas inlet tube, and condenser, 85 parts of n-butyl acrylate, 10 parts of methyl acrylate, 5 parts of acrylic acid, 0.3 part of 4-hydroxybutyl acrylate , 0.02 part of lauryl mercaptan, 0.1 part of 2,2-azobisisobutyronitrile and 200 parts of ethyl acetate were added, and after sufficient nitrogen substitution, the mixture was stirred at 55 ° C. while stirring under a nitrogen stream. The polymerization reaction was carried out at 65 ° C. for 3 hours to obtain an acrylic polymer having a weight average molecular weight of 750,000, a number average molecular weight of 170,000 and Mw / Mn = 4.4.

Here, the amount of the hydroxyl group-containing monomer was 0.3, the number average molecular weight (b) was 170,000, and a × b / 10 ⁴ was 5.1.

  To 100 parts of the solid content of the polymer solution, 0.3 part of dibenzoyl peroxide (1 minute half life 130 ° C.), 0.4 part of adduct of tolylene diisocyanate trimethylolpropane, 3-glycidoxypropyltri 0.1 part of methoxysilane was blended, 100 parts of ethyl acetate was blended as a diluent solvent, and an adhesive composition having a solid content of 25% and a solvent of 75% was prepared. The viscosity of this solution was 4.2 Pa · s, and a smooth surface was obtained even in the next adhesive application step. It is applied to 38μm PET after silicone release treatment so that the adhesive has a dry thickness of 25μm, dried and crosslinked at 150 ° C for 3 minutes, impregnated with polarizing film (polyvinyl alcohol film with iodine, and stretched) To which both sides were bonded with triacetylcellulose via an adhesive) to obtain an optical member with a pressure-sensitive adhesive of the present invention. The gel content of the pressure-sensitive adhesive layer was 71% by weight.

Example 2
In Example 1, 0.3 parts of 2-hydroxy-2-methyl- [4- (1-methylvinyl) phenyl] propanol oligomer was used instead of dibenzoyl peroxide, and the solid content was 25% and the solvent was A 75% pressure-sensitive adhesive composition was prepared. This composition was in the form of a solution and had a viscosity of 4.3 Pa · s. Even in the next pressure-sensitive adhesive application step, a smooth surface was obtained on the pressure-sensitive adhesive surface. The pressure-sensitive adhesive solution was applied to 38 μm PET, which had been subjected to silicone release treatment, so that the dry thickness of the pressure-sensitive adhesive was 25 μm, dried at 120 ° C. for 3 minutes, and then cross-linked. Irradiation was performed with an irradiation light amount of / cm ² and crosslinking treatment was performed. The film was transferred to a polarizing film (polyvinyl alcohol film impregnated with iodine, stretched, and triacetyl cellulose bonded to both sides via an adhesive) to obtain an optical member with an adhesive of the present invention. The gel content of the pressure-sensitive adhesive layer was 74%.

Example 3
98.5 parts of n-butyl acrylate, 0.5 part of acrylic acid, 1 part of 4-hydroxybutyl acrylate, 0.1 part of 2,2-azobisisobutyronitrile, 140 parts of ethyl acetate, 60 parts of toluene , Put into a 4-rottle flask equipped with a nitrogen introduction tube and a cooling tube, and after sufficiently purging with nitrogen, conduct a polymerization reaction at 55 ° C. for 10 hours and at 65 ° C. for 3 hours while stirring under a nitrogen stream, and weight average An acrylic polymer having a molecular weight of 840,000, a number average molecular weight of 160,000, and Mw / Mn = 5.3 was obtained. Here, the hydroxyl group-containing monomer amount (a) was 1, the number average molecular weight (b) was 160,000, and a × b / 10 ⁴ was 16.

  To 100 parts of the solid content of the polymer solution, 0.3 part of dibenzoyl peroxide (1 minute half-life 130 ° C.), 0.2 part of adduct of hexamethylene diisocyanate trimethylolpropane, N-phenylaminofluoro 0.1 part of rutrimethoxysilane was blended, 100 parts of ethyl acetate was blended as a diluent solvent, and an adhesive composition having a solid content of 25% and a solvent of 75% was prepared. The viscosity of this solution was 4.4 Pa · s, and the surface of the pressure-sensitive adhesive was smooth even in the next pressure-sensitive adhesive application step. It is applied to 38μm PET that has been subjected to silicone release treatment so that the dry thickness of the adhesive is 25μm, dried and crosslinked at 150 ° C for 3 minutes, impregnated with polarizing film (polyvinyl alcohol film with iodine, and stretched) To which both sides were bonded with triacetylcellulose via an adhesive) to obtain an optical member with a pressure-sensitive adhesive of the present invention. The gel content of the pressure-sensitive adhesive layer was 82%.

Example 4
In Example 1, 0.3 parts of 2-hydroxy-2-methyl [4- (1-methylvinyl) phenyl] propanol oligomer was used instead of dibenzoyl peroxide, the solid content was 25%, and the solvent was 75. % Pressure-sensitive adhesive composition was prepared. The viscosity of this solution was 4.4 Pa · s, and the surface of the pressure-sensitive adhesive was smooth even in the next pressure-sensitive adhesive application step. The pressure-sensitive adhesive solution was applied to 38 μm PET, which had been subjected to silicone release treatment, so that the dry thickness of the pressure-sensitive adhesive was 25 μm, dried at 120 ° C. for 3 minutes, and then cross-linked. Irradiated with an irradiation light amount of / cm ² and crosslinked. The film was transferred to a polarizing film (polyvinyl alcohol film impregnated with iodine, stretched, and triacetyl cellulose bonded to both sides via an adhesive) to obtain an optical member with an adhesive of the present invention. The gel content of the pressure-sensitive adhesive was 85%.

Comparative Example 1
85 parts of n-butyl acrylate, 10 parts of methyl acrylate, 5 parts of acrylic acid, 0.3 part of 4-hydroxybutyl acrylate, 0.1 part of 2,2-azobisisobutyronitrile and 200 parts of ethyl acetate, After putting into a 4-bowl flask equipped with a nitrogen introduction tube and a cooling tube, and sufficiently purging with nitrogen, a polymerization reaction is carried out at 55 ° C. for 22 hours while stirring under a nitrogen stream, and a weight average molecular weight of 1,840,000 and a number average molecular weight A high molecular weight polymer having 420,000 and Mw / Mn = 4.2 was obtained. 0.3 parts dibenzoyl baroxide (1 minute half-life 130.0 ° C.), 0.4 parts trimethylolpropane adduct of tolylene diisocyanate, 3-glycidoxy 0.1 part of propyltrimethoxysilane was blended, 100 parts of ethyl acetate was blended as a diluent solvent, and an adhesive composition having a solid content of 25% and a solvent of 75% was prepared. The viscosity of this solution was 15.5 Pa · s, and even in the next adhesive application step, the adhesive surface was in a state where a thread was pulled and a uniform adhesive was not obtained, but the gel fraction was 85. %Met.

Comparative Example 2
The same operation was performed except that 0.03 part of 4-hydroxybutyl acrylate was used in Example 1, and an optical member with a pressure-sensitive adhesive of Comparative Example 2 was obtained. The acrylic polymer had Mw of 750,000, Mn of 170,000, and Mw / Mn = 4.4, and the gel content of the pressure-sensitive adhesive layer was 65%. Here, the amount of the hydroxyl group-containing monomer was 0.03, the number average molecular weight (b) was 170,000, and a × b / 10 ⁴ was 0.51.

Comparative Example 3
The same operation was performed as in Example 1 except that 2.5 parts of 4-hydroxybutyl acrylate was used, and an optical member with a pressure-sensitive adhesive of Comparative Example 3 was obtained. In addition, Mw of the acrylic polymer was 700,000, Mn was 150,000, Mw / Mn = 4.7, and the gel content of the pressure-sensitive adhesive layer was 80%. Here, the amount of the hydroxyl group-containing monomer was 2.4, the number average molecular weight (b) was 150,000, and a × b / 10 ⁴ was 36.

Comparative Example 4
In Example 1, without using dibenzoyl peroxide, the adduct body of trimethylolpropane of tolylene diisocyanate was used as 0.6 part to obtain an optical member with an adhesive of Comparative Example 4. The gel content of the pressure-sensitive adhesive was 70%.

  The following evaluation was performed about the polarizing plate (sample) with an adhesive layer obtained by the said Example and comparative example. The evaluation results are shown in Table 1.

<Adhesive strength>
Samples obtained in Examples and Comparative Examples were cut into a width of 25 mm and a length of about 100 mm, and attached to a 0.5 mm-thick non-alkali glass plate (Corning Corp., 1737) with one reciprocating roll of 2 kg. Then, after autoclaving at 50 ° C. and 0.5 MPa for 30 minutes, the film was completely adhered, then left for 3 hours at 23 ° C. and 50% humidity, and then measured for peel adhesion at a peel angle of 90 ° and a peel speed of 300 mm / min. did.

  Further, after autoclaving, after standing for 6 hours at 70 ° C., for 3 hours under conditions of 23 ° C. and 50% RH, peeling adhesive strength (treatment adhesive strength: 90 ° peeling speed and 300 mm / min peeling speed). N / 25 mm) was measured and used as the adhesive strength after heating.

<Durability>
Samples obtained in Examples and Comparative Examples were attached to both surfaces of a 12-inch optical member having a thickness of 0.5 mm and alkali-free glass (Corning Corp., 1737) using a laminator. Next, after autoclaving at 50 ° C. and 0.5 MPa for 30 minutes, the mixture was put in an atmosphere at 90 ° C. for 500 hours.
○: There is no peeling or floating of the optical member.
X: There is peeling or floating of the optical member.

<Viscosity>
The viscosity of the pressure-sensitive adhesive composition was measured with a viscometer TV-20 manufactured by Toki Sangyo Co., Ltd. at 23 ° C. and 50% atmosphere at a rotation speed of 100 rpm.

Claims (10)

Weight by gel permeation chromatography obtained by copolymerizing 50% by weight or more of n-butyl acrylate, 0.1 to 2% by weight of a hydroxyl group-containing monomer, and 0 to 49.8% by weight of other monomers as monomer components. An acrylic polymer having an average molecular weight of 500,000 to 950,000 ; and 0.05 to 2 parts by weight of a radical generator and 0.05 to 2 parts by weight of an isocyanate-based crosslinking agent with respect to 100 parts by weight of the acrylic polymer. , And an adhesive composition for an optical member comprising 0.01 to 1 part by weight of a silane coupling agent, wherein the solid content is 25% by weight or more and the solvent is 75% by weight or less,
A pressure-sensitive adhesive composition for a solvent-based optical member, which has a viscosity at 23 ° C. and a B-type viscometer at 100 rpm of 8 Pa · s or less. Hydroxyl group-containing monomer wherein the hydroxyl group-containing monomer is represented by CH ₂ ═C (R ¹ ) COOC _n H _2n OH (where R ¹ is hydrogen or a methyl group, and n is an integer from 4 to 6) ( The pressure-sensitive adhesive composition for solvent-based optical members according to claim 1, which is a (meth) acrylate. The relationship between the weight percent (a) of the hydroxyl group-containing monomer in the acrylic polymer and the number average molecular weight (b) of the acrylic polymer is as follows:
The pressure-sensitive adhesive composition for solvent-based optical members according to claim 1, wherein 1 <a × b / 104 <20. The pressure-sensitive adhesive composition for solvent-based optical members according to any one of claims 1 to 3, wherein the radical generator is an organic peroxide. The pressure-sensitive adhesive composition for solvent-based optical members according to any one of claims 1 to 4, wherein the radical generator is a compound that generates radicals upon irradiation with active energy rays. A pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition for solvent-based optical members according to any one of claims 1 to 5. The pressure-sensitive adhesive layer according to claim 6, wherein the gel fraction is 40 to 90% by weight. The pressure-sensitive adhesive layer according to claim 6 or 7, wherein the solvent-soluble component has a weight average molecular weight of 100,000 or more. An optical member with an adhesive, wherein the adhesive layer according to any one of claims 6 to 8 is formed on at least one side of the optical member. The optical member with an adhesive according to claim 9, wherein the optical member is a material having an optical function such as a polarizing plate, a retardation plate, or an elliptical polarizing plate.