JP4740551B2 - Adhesive composition for discotic liquid crystal layer and optical functional film with viewing angle expansion function - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive composition for a discotic liquid crystal layer and an optical functional film with a viewing angle widening function, and more specifically, the discotic liquid crystal layer of an optical functional film having a discotic liquid crystal layer for widening the viewing angle. A pressure-sensitive adhesive composition for providing a pressure-sensitive adhesive layer thereon, and a pressure-sensitive adhesive composition capable of providing a pressure-sensitive adhesive layer excellent in adhesion and durability with a discotic liquid crystal layer, and the pressure-sensitive adhesive composition The present invention relates to an optical functional film with a viewing angle widening function obtained by using.

  The basic configuration of a liquid crystal display is a liquid crystal panel in which a liquid crystal is sandwiched between two glass substrates. From the image display format, it is necessary to dispose a polarizing element on the surface of the two glass substrates of the liquid crystal panel. Yes, usually with a polarizing film attached, but various other optical functional films for improving the quality of liquid crystal displays, such as retardation films, viewing angle widening films (optical compensation films), brightness enhancement films Etc. have been done.

  Among these optical functional films, as a viewing angle widening film, conventionally, an alignment layer of a liquid crystal polymer, in particular, an optical anisotropic layer in which a discotic liquid crystal is hybrid-aligned is represented by a triacetyl cellulose film (TAC film). As an independent optical functional film formed on the supporting film, it was used in the form of being attached to a polarizing film or other optical functional film via an adhesive layer.

  However, for example, particularly when the film is attached to a polarizing film, the polarizing film is obtained by sandwiching a polarizer (polyvinyl alcohol film or the like by adsorbing and orienting iodine) between two supporting films (TAC film or the like). The adhesive body has three adhesive films for bonding the supporting film of the polarizing film and the supporting film of the polarizing film and the supporting film of the viewing angle widening film together with the supporting film of the viewing angle widening film; Become.

On the other hand, with the expansion and diversification of applications, liquid crystal displays are required to be reduced in overall thickness.
Therefore, as one of the two supporting films, a polarizing film is prepared using a film in which a discotic liquid crystal layer is previously provided, and the discotic liquid crystal layer is directly applied to one of the supporting films of the polarizing film. It is proposed that a polarizing film with a viewing angle widening function is formed, and as a result, a polarizing film integrated with a viewing angle widening layer that is thinned by one supporting film and one adhesive layer. Yes.

  In the case of this viewing angle widening layer-integrated polarizing film, an adhesive layer is usually provided on the discotic liquid crystal layer, and the adhesive layer is attached to the glass substrate of the liquid crystal panel via the viewing angle. In order to cut (chip cut) the polarizing film with an enlargement function into dimensions according to the application, the adhesive layer provided on the discotic liquid crystal layer is also cut at the same time.

  Conventional methods for forming an adhesive layer for optical functional films such as polarizing films include acrylic resins containing functional groups that react with epoxy groups, silane compounds having functional groups that react with epoxy groups, and epoxy. A method using a pressure-sensitive adhesive composition comprising a compound having at least two groups and a crosslinking agent (see, for example, Patent Document 1), and an acrylic polymer having a carboxyl group and an isocyanate crosslinking agent A method of forming a pressure-sensitive adhesive composition by cross-linking the pressure-sensitive adhesive composition so that the ratio of the cross-linking agent that does not act on cross-linking becomes 70% or more is known (for example, see Patent Document 2). Yes.

However, these conventional adhesives have, of course, adhesion to an adherend (such as a glass substrate of a liquid crystal panel), and a film such as a TAC film that is usually used as a support for an optical functional film. There is no problem with the adhesiveness, but the adhesiveness with the discotic liquid crystal layer is low and not sufficient.
Therefore, as described above, when chip-cutting a polarizing film with a viewing angle widening function in which an adhesive layer is provided on a discotic liquid crystal layer, the adhesive layer near the cutting surface adheres to the cutting blade. As a result, it is removed from the discotic liquid crystal layer, resulting in defects in appearance and performance. Moreover, when it peels from some necessity after sticking to the glass substrate of a liquid crystal cell, an adhesive remains on a glass substrate and the adhesive residue will arise.

Japanese Patent Laid-Open No. 9-292525 Japanese Patent Laid-Open No. 2003-73639

  The present invention has been made in view of the prior art as described above, and of course has excellent adhesion to an adherend, excellent adhesion to a discotic liquid crystal layer, and is necessary for liquid crystal display applications. A pressure-sensitive adhesive composition for a discotic liquid crystal layer capable of forming a pressure-sensitive adhesive layer with excellent durability (heat resistance, water resistance, etc.) and an optical functional film with a viewing angle expansion function having the pressure-sensitive adhesive layer The purpose is that.

  As a result of intensive studies, the present inventors have found that the problem can be solved by using both the tolylene diisocyanate crosslinking agent (X) and the other crosslinking agent (Y) as the crosslinking agent for the acrylic polymer. I found it. The present invention has been completed based on such findings.

That is, the present invention
(1) A pressure-sensitive adhesive composition for providing a pressure-sensitive adhesive layer on a discotic liquid crystal layer of an optical functional film having a discotic liquid crystal layer for widening the viewing angle, the main component being an acrylic copolymer , Containing a tolylene diisocyanate crosslinking agent (X) and a xylylene diisocyanate crosslinking agent (Y) as a silane coupling agent and a crosslinking agent, and the content of the tolylene diisocyanate crosslinking agent (X) is an acrylic copolymer. Disco characterized in that the functional group equivalent of the polymer is 0.5 to 30 mmol, and the content of the xylylene diisocyanate crosslinking agent (Y) is 0.2 to 10 mmol in terms of the functional group equivalent of the acrylic copolymer. Adhesive composition for tick liquid crystal layer,
(2) The pressure-sensitive adhesive composition for a discotic liquid crystal layer according to the above (1), wherein the tolylene diisocyanate crosslinking agent (X) is tolylene diisocyanate or trimethylolpropane-modified tolylene diisocyanate,
( 3 ) With a viewing angle widening function in which a discotic liquid crystal layer and a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition for a discotic liquid crystal layer according to (1) or (2) above are sequentially provided on the surface of the optical functional film. ( 4 ) The optical functional film with a viewing angle widening function according to ( 3 ), wherein the optical functional film is a polarizing film in which a polarizer is sandwiched between two supporting films. ,
Is to provide.

  According to the present invention, of course, the adhesion to the adherend is excellent, the adhesion to the discotic liquid crystal layer is excellent, and the durability (heat resistance, water resistance, etc.) required for liquid crystal display applications is also excellent. It is possible to provide a pressure-sensitive adhesive composition for a discotic liquid crystal layer capable of forming a pressure-sensitive adhesive layer and an optical functional film with a viewing angle widening function having the pressure-sensitive adhesive layer.

  In the pressure-sensitive adhesive composition for discotic liquid crystal layer of the present invention (hereinafter sometimes simply referred to as “pressure-sensitive adhesive composition”), the acrylic copolymer is a monomer mixture mainly composed of (meth) acrylic acid alkyl ester. Copolymerized but copolymerized with (meth) acrylic acid alkyl ester having 4 or more carbon atoms in alkyl group and crosslinkable functional group-containing monomer, if necessary, with other copolymerizable monomers What was obtained by doing is preferable.

  Examples of the alkyl group (meth) acrylic acid alkyl ester having 4 or more carbon atoms in the alkyl group include butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( Examples include isooctyl (meth) acrylate and decyl (meth) acrylate. Moreover, the alkyl ester which has alicyclic groups or aromatic groups, such as (meth) acrylic-acid cycloalkyl ester and (meth) acrylic-acid benzyl ester, may be sufficient. These may be used alone or in combination of two or more.

The crosslinkable functional group-containing monomer is a monomer having a polymerizable double bond and a functional group such as hydroxyl group, carboxyl group, amino group, substituted amino group, and epoxy group in the molecule, preferably a hydroxyl group. Containing unsaturated compounds and carboxyl group-containing unsaturated compounds are used.
Specific examples of such functional group-containing monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and (meth) acrylic. (Meth) acrylic acid hydroxyalkyl esters such as 2-hydroxybutyl acid, 3-hydroxybutyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate; (meth) acetoacetoxymethyl acrylate; (meth) acrylic acid (Meth) acrylic acid monoalkylaminoalkyl such as monomethylaminoethyl, monoethylaminoethyl (meth) acrylate, (meth) acrylic acid monomethylaminopropyl, (meth) acrylic acid monoethylaminopropyl; acrylic acid, methacrylic acid, Crotonic acid, maleic acid, itacone Examples thereof include ethylenically unsaturated carboxylic acids such as acid and citraconic acid. These monomers may be used alone or in combination of two or more.

Examples of other copolymerizable monomers include (meth) acrylic acid alkyl esters having an alkyl group having 3 or less carbon atoms, such as methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic. Examples thereof include propyl acid, vinyl esters such as acrylonitrile, acrylamide, vinyl acetate and vinyl butyrate.
These may be used alone or in combination of two or more.

In the acrylic copolymer, the content ratio of the structural unit derived from the (meth) acrylic acid alkyl ester monomer having 4 or more carbon atoms in the alkyl group is 60% by mass or more in order to have the required tackiness. It is preferable.
That is, the range of the content ratio of the structural unit derived from a (meth) acrylic acid alkyl ester monomer having 4 or more carbon atoms in the alkyl group is preferably 60 to 99% by mass, particularly preferably 80 to 95% by mass. is there.

  In the acrylic copolymer, the structural unit derived from the crosslinkable functional group-containing monomer contributes to increase the cohesive force by forming a three-dimensional cross-linking bond with the cross-linking agent. For this reason, the content of the crosslinkable functional group-containing monomer is preferably 0.1 to 10% by mass, and particularly preferably 1 to 5% by mass.

  By introducing this structural unit derived from other copolymerizable monomers, the glass transition point (Tg) of the acrylic copolymer can be controlled, and the adhesive strength and cohesive strength of the adhesive layer can be adjusted. can do. For this reason, the content rate of the structural unit derived | led-out from the other monomer which can be copolymerized becomes like this. Preferably it is 0-40 mass%, Most preferably, it is 0-10 mass%.

The glass transition point (Tg) of the acrylic copolymer is preferably −10 ° C. or less, particularly preferably −60 to −10 ° C., in order to produce the necessary tackiness.
Further, the mass average molecular weight of the acrylic copolymer is preferably 100,000 or more in order to eliminate adverse effects such as odor due to residual monomers and contamination to the adherend, and obtain a viscosity necessary for applying the adhesive. Therefore, 2 million or less is preferable.
That is, the mass average molecular weight of the acrylic copolymer is preferably 10 to 2 million, and particularly preferably 200 to 1.5 million.

In the pressure-sensitive adhesive composition of the present invention, both a tolylene diisocyanate-based crosslinking agent (X) and another crosslinking agent (Y) are contained as a crosslinking agent.
Here, examples of tolylene diisocyanate-based crosslinking agent (X) include tolylene diisocyanate (TDI) and trimethylolpropane-modified tolylene diisocyanate (TDI-TMP).
Examples of other crosslinking agents (Y) include isocyanate crosslinking agents other than tolylene diisocyanate crosslinking agent (X), epoxy crosslinking agents, metal chelate crosslinking agents, and aziridine crosslinking agents.

  Examples of isocyanate crosslinking agents other than tolylene diisocyanate crosslinking agent (X) include hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), hydrogenated tolylene diisocyanate, diphenylmethane diisocyanate, etc. Examples thereof include polyisocyanates and adducts of these polyisocyanates and polyhydric alcohols, such as trimethylol bropan-modified XDI (XDI-TMP).

  Examples of epoxy crosslinking agents include 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, ethylene glycol di Examples thereof include glycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like.

  Examples of metal chelate-based crosslinking agents include chelate compounds composed of acetylacetone and acetone esters of divalent or higher metals such as aluminum, copper, iron, tin, zinc, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. Examples thereof include ethyl acetoacetate aluminum diisopropionate and aluminum tris (ethyl acetoacetate).

  Examples of the aziridine-based crosslinking agent include trimethylolpropane-tri-β-aziridinylpropionate, bisisophthaloyl-1- (2-methylaziridine), and the like.

Among these other cross-linking agents (Y), xylylene diisocyanate cross-linking agents such as xylylene diisocyanate (XDI) and trimethylolpropane-modified XDI (XDI-TMP) are excellent in durability after application. In particular, it is preferable.
One of these other crosslinking agents (Y) may be used alone, or two or more thereof may be used in combination.

The content of the tolylene diisocyanate crosslinking agent (X) in the pressure-sensitive adhesive composition is preferably in the range of 0.5 to 30 mmol in terms of the functional group equivalent of the acrylic copolymer in order to obtain the required adhesion. In particular, the range of 1 to 20 mmol is preferable.
The content of the other crosslinking agent (Y) is in the range of 0.2 to 10 mmol in terms of the functional group equivalent of the acrylic copolymer in order to obtain the required durability (heat resistance, water resistance, etc.). In particular, the range is 0.5 to 7 mmol.

The pressure-sensitive adhesive composition of the present invention improves the adhesion to a liquid crystal cell (glass) under wet heat conditions and makes it difficult for the optical functional film such as a polarizing film or a retardation film to float or peel off. Add ring agent.
This silane coupling agent is an organosilicon compound having at least one alkoxysilyl group in the molecule, having good compatibility with the pressure-sensitive adhesive component, and having light transparency, for example, substantially transparent Is preferred. Examples of such a silane coupling agent include vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, 3-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, 2- (3,4 -Epoxycyclohexyl) Ethyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane and the like.
The addition amount of the silane coupling agent is preferably in the range of 0.001 to 10 parts by mass, particularly preferably in the range of 0.005 to 5 parts by mass with respect to 100 parts by mass of the pressure-sensitive adhesive composition.
In the pressure-sensitive adhesive composition of the present invention, as long as the object of the present invention is not impaired, various known additives conventionally used in pressure-sensitive adhesive compositions, such as tackifiers, plasticizers, and antioxidants, are optionally added. An agent, an ultraviolet absorber and the like can be added.

The pressure-sensitive adhesive composition of the present invention is for providing a pressure-sensitive adhesive layer on the discotic liquid crystal layer of an optical functional film having a discotic liquid crystal layer for widening the viewing angle.
This discotic liquid crystal layer for expanding the viewing angle is an optically anisotropic layer in which a discotic liquid crystal compound that is a uniaxial compound is hybrid-aligned.
The discotic liquid crystal compound is S.I. Discovered by Chandrasekhar et al., "Pramana" 9, 471 has been published (1977), for example, the same authors entitled DiscoticLiquidCrystals by "Rep.Prog.Phys." 53 (1990) 57, or Shunsuke Takenaka As described in “Chemical Design and Synthesis of Discotic Liquid Crystal Molecules” in the Chemical Society of Japan / Quarterly Chemistry Review Volume 22, p. 60, there are several relatively long side chains on a disk-shaped core. It appears to be a bound compound.

  The types of compounds can be categorized mainly by the structure of the core, including 6-substituted benzene and 3-substituted benzene derivatives, phthalocyanine and porphyrin derivatives, triphenylene, torquesen and pyrylium derivatives, tribenzocyclononene derivatives, azacrown Derivatives, cyclohexane derivatives and the like.

The thickness of the pressure-sensitive adhesive layer provided on the discotic liquid crystal layer for expanding the viewing angle is preferably 5 to 100 μm, particularly preferably 10 to 50 μm.
As a method for providing this pressure-sensitive adhesive layer, for example, the pressure-sensitive adhesive composition is directly applied to a discotic liquid crystal layer by a known method to provide a pressure-sensitive adhesive layer, or the pressure-sensitive adhesive composition is provided on a release sheet. For example, a method may be used in which a pressure-sensitive adhesive layer is applied by a known method and then transferred to a discotic liquid crystal layer.
Examples of the method for applying the pressure-sensitive adhesive composition include a method using a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater and the like.

In addition, as an optical functional film having a discotic liquid crystal layer for widening the viewing angle to which the pressure-sensitive adhesive composition of the present invention can be applied, the discotic liquid crystal layer is directly applied to one of the polarizing film supporting films as described above. In addition to the polarizing film with the viewing angle widening function in the form of providing, for example, other optical functional films in the form of the retardation film and the brightness enhancement film in the form of similarly providing the discotic liquid crystal layer can also be exemplified.
Furthermore, even when the discotic liquid crystal layer is used as an independent optical functional film (viewing angle widening film) formed on the support film, when it is necessary to provide an adhesive layer on the discotic liquid crystal layer, The pressure-sensitive adhesive composition of the present invention can be effectively applied.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
In addition, each evaluation of the polarizing film with a viewing angle expansion function with an adhesive layer obtained in each example was performed according to the point shown below.
(1) Adhesive A polarizing film with a pressure-sensitive adhesive layer / discotic liquid crystal layer is cut into 233 mm × 309 mm with a super cutter (manufactured by Hadano Seiki Seisakusho Co., Ltd.), and the cut surface is visually observed with a loupe. Existence and state were observed and evaluated according to the following criteria.
◎: No glue chipping ○: There are glue chippings with a length of less than 100μm in several places △: There are glue chippings with a length of 100μm or more in several places ×: There are many chipping chips

(2) Reworkability A 125 mm × 25 mm pressure-sensitive adhesive layer / discotic liquid crystal layer-attached polarizing film was applied to non-alkali glass, then autoclaved, and left for 24 hours under conditions of 23 ° C. and 65% Rh. It peeled off from alkali glass, the glass surface was observed visually, the presence or absence of adhesive residue was observed, and the following reference | standard evaluated. In addition, the sticking conditions and peeling conditions were based on JIS Z0237.
○: No glue residue △: Some glue residue ×: There is glue residue

(3) Durability A polarizing film with an adhesive layer / discotic liquid crystal layer of 233 mm × 309 mm was pasted on an alkali-free glass, then autoclaved, and allowed to stand for 200 hours under conditions of 80 ° C. dry. The change in appearance was visually observed with a magnifying glass and evaluated according to the following criteria.
◎: No defects ○: Fine bubbles and streaks (length less than 100 μm)
Δ: Bubbles and streaks (length: 100 μm or more)
×: peeling

In the following examples and comparative examples, the following were used as the acrylic copolymer.
(Polymer A): 99 parts by mass of n-butyl acrylate, 1 part by mass of acrylic acid and 0.2 part by mass of azobisisobutyronitrile (initiator) are added to 200 parts by mass of ethyl acetate, and the mixture is 17 at 65 ° C. A polymer having a mass average molecular weight of 1,500,000 and a Tg of −54 ° C. obtained by stirring for a period of time.

(Polymer B): 89 parts by mass of n-butyl acrylate, 10 parts by mass of methyl acrylate, 1 part by mass of acrylic acid and 0.2 part by mass of azobisisobutyronitrile (initiator) in 200 parts by mass of ethyl acetate A polymer having a weight average molecular weight of 1.3 million and a Tg of −49 ° C. obtained by adding and stirring at 65 ° C. for 17 hours.

(Polymer C): 99 parts by mass of n-butyl acrylate, 1 part by mass of acrylic acid, and 0.2 part by mass of azobisisobutyronitrile (initiator) are added to 200 parts by mass of ethyl acetate, and 10 at 75 ° C. After stirring for a period of time, a solution of 49.5 parts by mass of n-butyl acrylate, 0.5 parts by mass of acrylic acid and 0.2 parts by mass of azobisisobutyronitrile (initiator) in 50 parts by mass of ethyl acetate was prepared. A polymer having a mass average molecular weight of 1,200,000 and a Tg of −54 ° C., which was obtained by adding dropwise over 4 hours and further stirring for 10 hours.

Furthermore, as a polarizing film with a viewing angle expansion function (with a discotic liquid crystal layer), a polarizing film having the following four-layer structure was used.
80 μm thick TAC film / iodine-adsorbed and oriented 20 μm thick polyvinyl alcohol film / 100 μm thick TAC film / 3 μm thick optically anisotropic layer (a discotic liquid crystal layer composed of a triphenylene derivative)

Example 1
1.60 parts by mass (functional group equivalent: 7.32 mmol) of tolylene diisocyanate crosslinking agent (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.), xylylene diisocyanate crosslinking agent (Mitsui Takeda Chemical Co., Ltd.) Product name: Takenate D-110N) 0.60 parts by mass (functional group equivalent 2.58 mmol) and silane coupling agent [manufactured by Shin-Etsu Chemical Co., Ltd., trade names: KBM-303, 2- (3,4-epoxy) (Cyclohexyl) ethyltrimethoxysilane] 0.06 part by mass was added and diluted with ethyl acetate to a concentration of 25% by mass to obtain an adhesive composition solution.
The adhesive composition solution is coated on a release treatment surface of a release film (trade name: SP-PET3811, release film obtained by release treatment on a 38 μm thick polyethylene terephthalate film) with a knife coater after drying. It was applied to a thickness of 25 μm and dried at 90 ° C. for 1 minute to form an adhesive layer. Next, this release film with an adhesive layer was superimposed on a polarizing film with a discotic liquid crystal layer so that the adhesive layer and the discotic liquid crystal layer were in contact with each other.
The polarizing film with the pressure-sensitive adhesive layer / discotic liquid crystal layer thus obtained was evaluated for adhesion, reworkability, and durability, and the results are shown in Table 1.

Example 2
Except for changing the amount of tolylene diisocyanate crosslinking agent from 1.60 parts by mass to 0.40 parts by mass (functional group equivalent 1.83 mmol), the same procedure as in Example 1 was carried out. An attached polarizing film was obtained.
The polarizing film with the pressure-sensitive adhesive layer / discotic liquid crystal layer thus obtained was evaluated for adhesion, reworkability, and durability, and the results are shown in Table 1.

Example 3
Except for changing the amount of tolylene diisocyanate-based crosslinking agent from 1.60 parts by mass to 3.20 parts by mass (functional group equivalent: 14.61 mmol), the pressure-sensitive adhesive layer and discotic liquid crystal layer were the same as in Example 1. An attached polarizing film was obtained.
The polarizing film with the pressure-sensitive adhesive layer / discotic liquid crystal layer thus obtained was evaluated for adhesion, reworkability, and durability, and the results are shown in Table 1.

Example 4
Except that the amount of the xylylene diisocyanate-based crosslinking agent was changed from 0.60 parts by mass to 0.15 parts by mass (functional group equivalent 0.63 mmol), in exactly the same manner as in Example 1, the pressure-sensitive adhesive layer / discotic liquid crystal layer An attached polarizing film was obtained.
The polarizing film with the pressure-sensitive adhesive layer / discotic liquid crystal layer thus obtained was evaluated for adhesion, reworkability, and durability, and the results are shown in Table 1.

Example 5
Except for changing the amount of the xylylene diisocyanate crosslinking agent from 0.60 parts by mass to 1.20 parts by mass (functional group equivalent: 5.13 mmol), the pressure-sensitive adhesive layer / discotic liquid crystal layer was the same as in Example 1. An attached polarizing film was obtained.
The polarizing film with the pressure-sensitive adhesive layer / discotic liquid crystal layer thus obtained was evaluated for adhesion, reworkability, and durability, and the results are shown in Table 1.

Example 6
A polarizing film with a pressure-sensitive adhesive layer and a discotic liquid crystal layer was obtained in the same manner as in Example 1 except that the polymer A was changed to the polymer B having the same mass.
The polarizing film with the pressure-sensitive adhesive layer / discotic liquid crystal layer thus obtained was evaluated for adhesion, reworkability, and durability, and the results are shown in Table 1.

Example 7
A polarizing film with a pressure-sensitive adhesive layer and a discotic liquid crystal layer was obtained in the same manner as in Example 1 except that the polymer A was changed to the polymer C having the same mass.
The polarizing film with the pressure-sensitive adhesive layer / discotic liquid crystal layer thus obtained was evaluated for adhesion, reworkability, and durability, and the results are shown in Table 1.

Example 8
Polymer A is changed to polymer C of the same mass, and 0.60 part by mass of xylylene diisocyanate crosslinking agent is 0.24 part by mass of epoxy crosslinking agent (trade name: TETRAD-C, manufactured by Mitsubishi Gas Chemical Company) (functional group). A polarizing film with an adhesive layer and a discotic liquid crystal layer was obtained in exactly the same manner as in Example 1 except that the equivalent amount was changed to 2.60 mmol).
The polarizing film with the pressure-sensitive adhesive layer / discotic liquid crystal layer thus obtained was evaluated for adhesion, reworkability, and durability, and the results are shown in Table 1.

Example 9
Polymer A is changed to polymer C of the same mass, and 0.60 parts by mass of xylylene diisocyanate crosslinking agent is 0.36 parts by mass of aluminum chelate crosslinking agent (trade name: ALCH-TR, manufactured by Kawaken Fine Chemical Co., Ltd.) A polarizing film with a pressure-sensitive adhesive layer and a discotic liquid crystal layer was obtained in the same manner as in Example 1 except that the base equivalent was changed to 2.61 mmol).
The polarizing film with the pressure-sensitive adhesive layer / discotic liquid crystal layer thus obtained was evaluated for adhesion, reworkability, and durability, and the results are shown in Table 1.

Example 10
Polymer A is changed to polymer C of the same mass, and 0.60 parts by mass of xylylene diisocyanate-based crosslinking agent is 0.37 parts by mass of aziridine-based crosslinking agent (trade name: TAZM, manufactured by Mutual Pharmaceutical Co., Ltd.) (functional group equivalent 2 A polarizing film with an adhesive layer and a discotic liquid crystal layer was obtained in exactly the same manner as in Example 1 except that the amount was changed to .58 mmol).
The polarizing film with the pressure-sensitive adhesive layer / discotic liquid crystal layer thus obtained was evaluated for adhesion, reworkability, and durability, and the results are shown in Table 1.

Comparative Example 1
In the same manner as in Example 1 except that only 1.60 parts by mass (functional group equivalent: 7.32 mmol) of tolylene diisocyanate-based crosslinking agent (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) was used as the crosslinking agent. A polarizing film with an agent layer and a discotic liquid crystal layer was obtained.
The polarizing film with the pressure-sensitive adhesive layer / discotic liquid crystal layer thus obtained was evaluated for adhesion, reworkability, and durability, and the results are shown in Table 1.

Comparative Example 2
Except that only 0.60 parts by mass (functional group equivalent: 2.58 mmol) of xylylene diisocyanate-based crosslinking agent (trade name: Takenate D-110N, manufactured by Mitsui Takeda Chemical Co., Ltd.) was used as the crosslinking agent. Thus, a polarizing film with an adhesive layer and a discotic liquid crystal layer was obtained.
The polarizing film with the pressure-sensitive adhesive layer / discotic liquid crystal layer thus obtained was evaluated for adhesion, reworkability, and durability, and the results are shown in Table 1.

Comparative Example 3
In the same manner as in Example 1 except that only 0.24 parts by mass (functional group equivalent: 2.60 mmol) of an epoxy-based crosslinking agent (trade name: TETRAD-C, manufactured by Mitsubishi Gas Chemical Company, Inc.) was used as the crosslinking agent. A polarizing film with an agent layer and a discotic liquid crystal layer was obtained.
The polarizing film with the pressure-sensitive adhesive layer / discotic liquid crystal layer thus obtained was evaluated for adhesion, reworkability, and durability, and the results are shown in Table 1.

Comparative Example 4
0.60 parts by mass (functional group equivalent: 2.58 mmol) of xylylene diisocyanate-based crosslinking agent (trade name: Takenate D-110N, manufactured by Mitsui Takeda Chemical Co., Ltd.) and an epoxy-based crosslinking agent (produced by Mitsubishi Gas Chemical Co., Ltd., products) Name: TETRAD-C) A polarizing film with an adhesive layer and a discotic liquid crystal layer was obtained in exactly the same manner as in Example 1 except that 0.24 parts by mass (functional group equivalent: 2.60 mmol) was used.
The polarizing film with the pressure-sensitive adhesive layer / discotic liquid crystal layer thus obtained was evaluated for adhesion, reworkability, and durability, and the results are shown in Table 1.

The pressure-sensitive adhesive composition of the present invention has excellent adhesion to the adherend, of course, excellent adhesion to the discotic liquid crystal layer, and durability required for liquid crystal display applications (heat resistance, water resistance, etc.) And is suitable for the production of a liquid crystal display of a type in which an optical functional film having a discotic liquid crystal layer directly provided on a support film is attached to a liquid crystal panel.

Claims (4)

An adhesive composition for providing an adhesive layer on the discotic liquid crystal layer of the optical functional film having a discotic liquid crystal layer for widening the viewing angle,
The main component is an acrylic copolymer, and it contains a tolylene diisocyanate crosslinking agent (X) and a xylylene diisocyanate crosslinking agent (Y) as a silane coupling agent and a crosslinking agent.
The tolylene diisocyanate crosslinking agent (X) content is 0.5 to 30 mmol in terms of the functional group equivalent of the acrylic copolymer, and the xylylene diisocyanate crosslinking agent (Y) content is that of the acrylic copolymer. A pressure-sensitive adhesive composition for a discotic liquid crystal layer, having a functional group equivalent of 0.2 to 10 mmol.   The pressure-sensitive adhesive composition for a discotic liquid crystal layer according to claim 1, wherein the tolylene diisocyanate crosslinking agent (X) is tolylene diisocyanate or trimethylolpropane-modified tolylene diisocyanate. An optical functional film with a viewing angle widening function, wherein a discotic liquid crystal layer and a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive composition for a discotic liquid crystal layer according to claim 1 or 2 are sequentially provided on the surface of the optical functional film. . 4. The optical functional film with a viewing angle widening function according to claim 3 , wherein the optical functional film is a polarizing film in which a polarizer is sandwiched between two supporting films.