KR101074501B1 - Acrylic pressure-sensitive adhesive composition comprising optically anisotropic compound, polarizing plate and liquid crystal display device comprising the same - Google Patents

Abstract

The present invention (A) an acrylic copolymer containing an aromatic group; And (B) an acrylic pressure-sensitive adhesive composition comprising an optically anisotropic compound having at least one substituent containing an alkyl group, an alkenyl group or an alkynyl group in the meta position of mesogen, a polarizing plate and a liquid crystal display comprising the same. It occurs due to the shrinkage stress of the polarizing plate without changing the main characteristics such as adhesive durability, which may occur under high temperature or high temperature and high humidity conditions, including an acrylic monomer and an optically anisotropic compound containing an aromatic group having positive birefringence in the pressure sensitive adhesive By controlling the birefringence characteristic to improve the light leakage phenomenon.

Acrylic pressure sensitive adhesive, an acrylic monomer containing an aromatic group, an optically anisotropic compound, light leakage, optical compensation, and a polarizing plate.

Description

Acrylic pressure-sensitive adhesive composition comprising an optically anisotropic compound, a polarizing plate and a liquid crystal display comprising the same {Acrylic pressure-sensitive adhesive composition comprising optically anisotropic compound, polarizing plate and liquid crystal display device comprising the same}

The present invention relates to an acrylic pressure-sensitive adhesive composition, and more particularly, to an acrylic copolymer containing an aromatic group and an optically anisotropic compound having high optical anisotropy and excellent compatibility with an acrylic copolymer, and having excellent durability in high temperature or high temperature and high humidity conditions. In addition, the present invention relates to an acrylic pressure-sensitive adhesive composition having improved light leakage phenomenon by effectively controlling the birefringence phenomenon caused by shrinkage of the polarizing plate under such endurance reliability conditions, a polarizing plate manufactured therefrom, and a liquid crystal display device using the same.

In general, in order to manufacture a liquid crystal display device, a liquid crystal cell and a polarizing plate including a liquid crystal are basically required, and an appropriate adhesive layer or adhesive layer for bonding them should be used. In addition, in order to improve the function of the liquid crystal display, a retardation plate, a wide viewing angle compensation plate, or a brightness enhancement film may be additionally attached to the polarizing plate.

The main structure for forming the liquid crystal display device includes a liquid crystal layer that is constantly arranged; A polarizing plate having a multi-layered structure integrated with an adhesive layer or an adhesive layer based on a liquid crystal cell composed of a transparent glass plate or a plastic plate-like material including a transparent electrode layer; Retardation plate; And further functional film layers and the like.

At this time, the polarizing plate is a structure containing an iodine-based compound or a dichroic polarizing material arranged in a predetermined direction, in order to protect these polarizing devices by using a protective film such as a triacetyl cellulose (TAC) -based on both sides Will be configured. In addition, the polarizing plate may additionally include a retardation film of a shape having a unidirectional molecular array, a wide viewing angle compensation film such as a liquid crystal film.

Each of the above-mentioned films has different physical properties because they are made of materials having different molecular structures and compositions. In particular, under high temperature and high temperature and high humidity conditions, dimensional stability due to shrinkage or expansion of materials having a unidirectional molecular arrangement is insufficient. Therefore, when the polarizing plate is fixed by the pressure-sensitive adhesive, stress is concentrated and birefringence is generated in the TAC layer due to shrinkage or expansion of the polarizing plate under high temperature and high temperature and high humidity conditions, resulting in light leakage. In this case, negative birefringence generally appears as a whole by the contracted TAC.

This light leakage phenomenon can be suppressed by adjusting the stress relaxation property of the adhesive fixed to the polarizing plate so that residual stress does not remain. This can be achieved when the adhesive used is an uncrosslinked structure.

However, the adhesive layer requires high high temperature cohesion to maintain durability, and for this purpose, it is used in the form of a partially crosslinked viscoelastic material, thereby exhibiting suitable adhesive properties.

Therefore, the adhesive layer used in the form of a partially crosslinked viscoelastic material has a residual stress under a given stress, and the polymer in the crosslinked structure is oriented in a specific direction to exhibit birefringence. Under this orientation, the acrylic pressure sensitive adhesive will exhibit negative birefringence.

Recently, as the LCD panel is enlarged, the polarizing plate is also enlarged. Accordingly, the shrinkage of the polarizing plate is increased and the residual stress of the adhesive layer is increased under heat or moisture resistant conditions, so that the overall negative birefringence is increased and the light leakage phenomenon is more severe. In order to minimize such light leakage phenomenon, it is necessary to provide optical compensation for adjusting the negative birefringence of the pressure-sensitive adhesive represented by residual stress to positive birefringence.

A method for minimizing birefringence by copolymerizing a monomer having a positive birefringence with a monomer having a positive birefringence under residual stress is known (see Applied Optics (1997)). As a specific example, the degree of birefringence can be adjusted under a given stress by copolymerizing an acrylic monomer (negative birefringence) in which the side chain has an alkyl group and an acrylic monomer (positive birefringence) in which the side chain has an aromatic group.

Korean Patent Laid-Open Publication No. 2003-0069461 discloses a technical idea of correcting negative birefringence represented by an acrylic pressure-sensitive adhesive layer under residual stress by incorporating 0.01 to 40 parts by weight of a low molecular weight substance showing positive birefringence under residual stress in an acrylic pressure-sensitive adhesive layer. . However, the compatibility of the used low-molecular weight and the pressure-sensitive adhesive can be a problem, the use of excess is likely to appear phase separation with the pressure-sensitive adhesive, there is a possibility of a problem in light transmittance or durability.

Japanese Laid-Open Patent Publication No. 2002-332468 describes a method of improving the plasticizer resistance of an adhesive layer by introducing an acrylic monomer containing an aromatic group in a side chain. U.S. Pat.Nos. 666,397,8, JP 2002-173656 and 2003-013029 describe a method of controlling the refractive index of the pressure-sensitive adhesive layer by introducing an acrylic monomer containing an aromatic group in the side chain.

Japanese Laid-Open Patent Publication No. 2005-053976 describes a method of introducing an acrylic monomer containing an aromatic group into a side chain to improve adhesive performance even for a low polar film.

However, as the polarizing plate becomes larger, the stress applied to the left and right edges increases, and it is insufficient to compensate for the negative birefringence of the polarizing plate due to shrinkage only with the acrylic copolymer containing an aromatic group under the residual stress.

An object of the present invention is to solve the problems of the prior art as described above, and may occur under high temperature or high temperature and high humidity conditions, including an acrylic copolymer containing an aromatic group and a compound having high optical anisotropy and excellent compatibility with the acrylic copolymer. It is to provide an optically compensated acrylic pressure-sensitive adhesive composition which improves light leakage by controlling the pressure-sensitive adhesive to have a positive birefringence under residual stress without changing the main characteristics such as the pressure-resistance reliability.

Another object of the present invention is to provide a polarizing plate comprising an acrylic pressure-sensitive adhesive composition having the above characteristics.

Still another object of the present invention is to provide a liquid crystal display device including the polarizing plate.

The present invention is an acrylic copolymer containing an aromatic group (A) as a means for solving the above problems; And (B) an optically anisotropic compound having at least one substituent containing an alkyl group, an alkenyl group or an alkynyl group in the meta position of mesogen.

The present invention provides a polarizing film as another means for solving the above problems; And a pressure-sensitive adhesive layer formed on one or both surfaces of the polarizing film and containing an acrylic pressure-sensitive adhesive composition having the above characteristics.

The present invention provides a liquid crystal display including a liquid crystal panel in which the polarizing plate is bonded to one side or both sides of a liquid crystal cell as another means for solving the above problems.

The acrylic pressure-sensitive adhesive composition of the present invention includes an aromatic monomer containing an aromatic group and a compound having high optical anisotropy, excellent compatibility with an acrylic copolymer, and a compound having high optical anisotropy, such as adhesive durability reliability that may occur under high temperature or high temperature and high humidity conditions. The birefringence characteristic generated due to the shrinkage stress of the polarizing plate is controlled without changing the main characteristic of, thereby improving the light leakage phenomenon of the polarizing plate.

The present invention (A) an acrylic copolymer containing an aromatic group; And (B) an optically anisotropic compound having at least one substituent containing an alkyl group, alkenyl group or alkynyl group in the meta position of mesogen.

The present invention introduces an acrylic copolymer containing an aromatic group and a compound having high optical anisotropy in a pressure-sensitive adhesive that exhibits negative birefringence under residual stress to have a positive birefringence under residual stress, thereby providing a negative birefringence present in the TAC layer of the contracted polarizing plate. It is characterized in that to optically compensate for the light leakage phenomenon.

Hereinafter, each component of the acrylic pressure-sensitive adhesive composition according to the present invention will be described in more detail.

(A) Aromatic groups  Acrylic copolymer containing

(A) The acrylic copolymer containing an aromatic group includes, but is not limited to, i) a (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms; Ii) an aromatic group-containing acrylic monomer copolymerizable with the alkyl (meth) acrylic acid ester monomer; And iii) a crosslinkable functional group-containing monomer.

(Iii) The (meth) acrylic acid ester monomer having a group having an alkyl group having 1 to 14 carbon atoms is not limited thereto, but methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso Propyl (meth) acrylate, butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, iso At least one selected from the group consisting of octyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate, and tetradecyl (meth) acrylate can be used.

If carbon number of an alkyl group is out of the said range, the glass transition temperature (Tg) of an adhesive will become high or it will be difficult to adjust adhesiveness. In addition, the content of the alkyl (meth) acrylic acid ester monomer having 1 to 14 carbon atoms is preferably 55 to 95 parts by weight. When the content is less than 55 parts by weight, the amount of the aromatic group-containing acrylic monomer is increased, thereby making it difficult to obtain a sufficient molecular weight and increasing the Tg of the pressure-sensitive adhesive is difficult to exhibit the adhesive performance suitable for the application. In addition, when the content is more than 95 parts by weight, the amount of aromatic group-containing acrylic monomer is less, which is insufficient to obtain sufficient optical compensation effect.

The ii) aromatic group-containing acrylic monomer copolymerizable with the alkyl (meth) acrylic acid ester monomer exhibits positive birefringence, and serves to correct negative birefringence of the acrylic adhesive under residual stress.

As the aromatic group-containing acrylic monomer, it is preferable to use a compound represented by the following formula (1).

[Formula 1]

Where

R ₁ is hydrogen or a methyl group,

R ₂ is an alkylene group having 1 to 12 carbon atoms,

n is an integer of 0 to 3, preferably an integer of 0 or 1,

X is oxygen, sulfur or an alkylene group having 1 to 4 carbon atoms,

Ar is an aromatic group unsubstituted or substituted with halogen or alkyl having 1 to 12 carbon atoms.

Examples of the compound represented by Formula 1 include phenoxy ethyl (meth) acrylate, benzyl (meth) acrylate, 2-phenylthio-1-ethyl (meth) acrylate, and 6- (4,6-dibro). Mo-2-isopropyl phenoxy) -1-hexyl (meth) acrylate, 6- (4,6-dibromo-2-sec-butyl phenoxy) -1-hexyl (meth) acrylate, 2, 6-dibromo-4-nonylphenyl (meth) acrylate, 2,6-dibromo-4-dodecyl phenyl (meth) acrylate, 2- (1-naphthyloxy) -1-ethyl (meth ) Acrylate, 2- (2-naphthyloxy) -1-ethyl (meth) acrylate, 6- (1-naphthyloxy) -1-hexyl (meth) acrylate, 6- (2-naphthyloxy ) -1-hexyl (meth) acrylate, 8- (1-naphthyloxy) -1-octyl (meth) acrylate, or 8- (2-naphthyloxy) -1-octyl (meth) acrylate, etc. These can be used individually or in mixture of 2 or more types.

Preferably phenoxy ethyl (meth) acrylate, benzyl (meth) acrylate, 2-phenylthio-1-ethyl (meth) acrylate, 2- (1-naphthyloxy) -1-ethyl (meth) acrylic 8- (2-naphthyloxy) -1-octyl (meth) acrylate can be used, More preferably, phenoxy ethyl (meth) acrylate or benzyl (meth) acrylate can be used.

The content of the aromatic group-containing acrylic monomer is preferably 5 to 35 parts by weight. When the content is less than 5 parts by weight, the final pressure-sensitive adhesive exhibits a negative birefringence under the residual stress, and there is a disadvantage in that an excessive amount of the optically anisotropic compound described later is used. When the content is more than 35 parts by weight, the adhesive balance of the final acrylic pressure-sensitive adhesive deteriorates In addition, the adhesive force is greatly increased and the re-peelability of the polarizing plate is not very poor, and the positive birefringence of the pressure-sensitive adhesive becomes severe under residual stress, and the light leakage becomes stronger.

(Iii) The crosslinkable functional group-containing monomer is not limited thereto, and for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate Hydroxyl group-containing monomers such as 2-hydroxyethylene glycol (meth) acrylate or 2-hydroxypropylene glycol (meth) acrylate; Carboxyl group-containing monomers such as acrylic acid, methacrylic acid, acrylic acid duplex, itaconic acid, carboxyethyl acrylate, carboxypentyl acrylate, maleic acid, or fumaric acid; And nitrogen-containing monomers such as acrylamide, N-vinyl pyrrolidone, or N-vinyl caprolactam, and the like, and these may be used alone or in combination of two or more thereof.

(Iii) The content of the crosslinkable functional group-containing monomer is preferably 0.1 to 10 parts by weight of the total monomers. When the content is less than 0.1 part by weight, the adhesive force and cohesion force is weak, and when the content exceeds 10 parts by weight, the adhesive force and peeling force are lowered.

It is preferable that the weight average molecular weights of the acrylic copolymer containing the said (A) aromatic group are 800,000-2 million. When the weight average molecular weight is less than 800,000, the cohesive strength of the pressure-sensitive adhesive is insufficient, the durability reliability is poor, and when the weight-average exceeds 2 million, the stress relaxation effect is insufficient.

In the present invention (A) the acrylic copolymer containing an aromatic group may further include a copolymerization monomer in order to control the glass transition temperature of the pressure-sensitive adhesive or to impart other functionality. Specific examples of the copolymer monomer include styrene monomers such as styrene or alpha methyl styrene; Carboxylic acid vinyl esters such as vinyl acetate; Nitrogen-containing monomers such as acrylonitrile, (meth) acrylamide, N-methyl (meth) acrylamide, or N-butoxy methyl (meth) acrylamide; and the like, and these may be used alone or in combination of two or more thereof. Can be.

The polymerization method of the acrylic copolymer containing the aromatic group (A) is not particularly limited, and may be prepared by a solution polymerization method, a photopolymerization method, a bulk polymerization method, a suspension polymerization method, or an emulsion polymerization method.

Preferably, the acrylic copolymer containing the aromatic group is prepared by a solution polymerization method, the polymerization temperature is preferably 50 to 140 ℃, it is preferable to add a polymerization initiator in a state where the monomers are uniformly mixed.

The polymerization initiator may be selected from azo polymerization initiators such as azobisisobutyronitrile or azobiscyclohexanecarbonitrile; And peroxides, such as benzoyl peroxide or acetyl peroxide, can be used individually or in mixture.

(B) Mesogen Meta  An alkyl group at the position, Alkenyl groups  or Alkynyl groups  Optics with one or more substituents containing Anisotropy  compound

The term mesogen in the present invention means a rod structure including one or more aromatic rings connected in one direction.

The optically anisotropic compound having at least one substituent containing an alkyl group, an alkenyl group or an alkynyl group in the meta position of mesogen serves to optically compensate for the negative birefringence of the acrylic pressure sensitive adhesive to improve light leakage.

In general, optically anisotropic compounds having high birefringence have high crystallinity and low compatibility with polymer resins, so that even if a small amount is used, phase separation occurs and crystallization occurs. In order to solve this problem, the present invention introduces one or more substituents containing an alkyl group, an alkenyl group, or an alkynyl group at the meta position of mesogen. Substituents introduced at the meta position of the mesogen core increase the compatibility with the polymer resin and improve physical properties such as solubility and melting point, as compared to the conventional para ( sub position) substituents.

In the present invention, the optically anisotropic compound may have a meta substituent and a para substituent at the same time, but more preferably has only a meta substituent.

It is preferable that the said optically anisotropic compound contains the compound represented by following formula (2).

[Formula 2]

Where

는

또는

이고;

Is

or

ego;

는

또는

이며;

Is

or

Is;

는

또는

이고;

Is

or

ego;

Z is C-W or N;

Q ₁ to Q ₁₅ , and W are each independently hydrogen, halogen, cyano, —R ₅ , —OR ₅ , —NHR ₅ , —NR ₅ R ₅ or —C (═O) R ₅ ;

l, m and n are each independently an integer of 0 to 3, and l + m + n is an integer of 1 or more;

Y, G ₁ , G ₂ , X ₁ and X ₂ are each independently a single bond, -O-, -NR _5- , -S-, -SO-, -SO _2- , alkylene of C ₁ to C ₆ , C ₂ to C ₆ alkenylene, C ₂ to C ₆ alkynylene, or -UTV-,

Where -T- is carbonyl (-C (= O)-), U and V are each a single bond, -O-, -NR _5- , -S-,-(CH ₂ ) _p- , -O ( CH ₂ ) _p -or-(CH ₂ ) _p O-, p is an integer from 1 to 5,

E is hydrogen, halogen, cyano, -NCO, -NCS, -R ₅ , or -OR ₅ ;

R ₃ , R ₄ and R ₅ are each independently hydrogen, C ₁ to C ₂₀ alkyl unsubstituted or substituted with one or more halogens, C ₂ to C ₂₀ eggs unsubstituted or substituted with one or more halogens. Alkenyl, C ₂ to C ₂₀ alkynyl substituted or unsubstituted with one or more halogens, or — (R ₆ O) _q R ₇ , wherein R ₆ is C ₁ To C ₆ alkylene, R ₇ is C ₁ To C ₄ alkyl, q is an integer of 1 to 5, but R ₃ and R ₄ Does not include the case where is hydrogen at the same time.

Specifically, the compound represented by Formula 2 may include one or more substituents (X ₁ -R ₃ or X ₂ -R ₄ ) containing an alkyl group, an alkenyl group, or an alkynyl group at a meta position of mesogen. In this case, l + m + n of the mesogen core is an integer of 1 or more.

In the compound represented by Formula 2, Y, G ₁ , and G ₂ are specifically, for example, each independently a single bond, -O-, -NR _5- , -S-, -SO-, -SO _2- , -(CH ₂ ) _p- , -CH = CH-, -C≡C-, -C (= O) O-, -OC (= O)-, -C (= O)-, -C (= O ) NR _5- , -NR ₅ C (= 0)-, -C (= 0) S-, -SC (= 0)-, -C (= 0) O (CH ₂ ) _p- , -OC (= O) (CH ₂ ) _p −, — (CH ₂ ) _p OC (═O) —, or — (CH ₂ ) _p C (═O) O— and the like. In addition, each of G ₁ and G ₂ is independently a single bond, -CH = CH- or -C≡C-, and more preferably a single bond or -C 보다 C-.

In addition, in the compound represented by Formula 2, X ₁ and X ₂ are each independently a single bond, -O-, -NR _5- , -S-, -SO-, -SO ₂ -,-(CH ₂ ) _p- , -C (= 0) NR _5- , -NR ₅ C (= 0)-, -NR ₅ C (= 0) NR _5- , -C (= 0) O-, -OC (= 0)-, Or -OC (= 0) O-, and p is preferably an integer of 1 to 2.

In the compound represented by Formula 2 of R ₃ , R ₄ and R ₅ Alkyl of C ₁ to C ₂₀ is, for example, -CH ₃ , -CH ₂ CH ₃ , -CH ₂ CH ₂ CH ₃ , -CH (CH ₃ ) ₂ , -CH ₂ CH ₂ CH ₂ CH ₃ , Linear or branched alkyl such as -CH (CH ₃ ) CH ₂ CH ₃ , or -CH ₂ CH (CH ₃ ) _2, and the like.

And also R ₃ , R ₄ and R ₅ Alkenyl of C ₂ to C ₂₀ is, for example, -CH = CH ₂ , -CH = CHCH ₃ , -CCH ₃ = CH ₂ , -CH ₂ CH = CH ₂ , -CH = CHCH ₂ CH ₃ , -CH = C (CH ₃ ) ₂ , -CCH ₃ = CHCH ₃ , -CH ₂ CH = CHCH ₃ , -CH ₂ CCH ₃ = CH ₂ , -CHCH ₃ CH = CH ₂ , or -CH ₂ CH ₂ CH Linear or branched alkenyl, such as = CH _2, and the like.

In addition, R ₃ , R ₄ and R ₅ Alkynyl of C ₂ to C ₂₀ is, for example, -C≡CH, -CH ₂ C≡CH, -C≡CCH ₃ , -CH ₂ CH ₂ C≡CH, -CHCH ₃ C≡CH, Linear or branched alkynyl such as -CH ₂ C≡CCH ₃ , or -C≡CCH ₂ CH _3, and the like.

Preferably, in the compound represented by Formula 2, R ₃ and R ₄ are each independently a linear or branched C ₃ to C ₁₂ alkyl, C ₃ to C ₁₂ alkyl, unsubstituted or substituted with one or more halogens. for alkenyl, or C ₃ to C ₁₂ alkynyl which will of, substituted with one or more halogen or unsubstituted branched of C ₃ to alkyl of C _12, C ₃ to alkenyl of C ₁₂ ring, or C ₃ to C ₁₂ It is more preferable that it is alkynyl.

In addition, in the compound represented by Formula 2,-(R ₆ O) _q R ₇ corresponding to R ₃ , R ₄ and R ₅ are each independently-(CH ₂ CH ₂ O) _q CH ₃ ,-(CH ₂ CHCH ₃ O) _q CH ₃ or-(CHCH ₃ CH ₂ O) _q CH ₃ , and q is an integer of 1-5.

If the compound represented by the formula (2) more specifically expressed as follows, but is not limited to the compound illustrated below.

One)

2)

3)

4)

5)

6)

7)

8)

9)

Acrylic pressure-sensitive adhesive composition according to the present invention may include a compound represented by the formula (2) alone or two or more, the content thereof is 0.5 to 20 parts by weight based on 100 parts by weight of the acrylic copolymer containing (A) an aromatic group. desirable. If the content is less than 0.5 parts by weight, the optical compensation effect of the pressure-sensitive adhesive is inferior, and if the content exceeds 20 parts by weight, the positive birefringence of the pressure-sensitive adhesive to the shrinkage of the polarizer because the copolymer contains an aromatic group and has some amount of birefringence under residual stress It is larger than the negative birefringence caused by the light leakage phenomenon.

The method for preparing the compound represented by Chemical Formula 2 may use a conventional method used in the art, but is not limited thereto, and may be prepared, for example, by the following method.

[Reaction Scheme]

Where

A can be -YH, -OH, -L, or -B (OH) ₂ , or the like, D can be HY-, HO-, L- or (HO) ₂ B- or the like. L is a leaving group, but is not limited thereto. For example, halides, mesylates, tosylates or triflate may be used. Symbols other than that are the same as the definition of the formula (2).

The solvent of the reaction is hexane, ether, dichloromethane, tetrahydrofuran (THF), Dioxane, Butanone, ethanol, ethyl acetate, water or a mixture thereof; Or a benzene solvent such as benzene or toluene, the reaction temperature is 0 to 200 ° C, and the reaction time is 1 to 30 hours.

In addition, according to the type of reaction can be used a catalyst used in the art, for example, Pd, Cu, or Ni may be used.

Specific preparation method of the compound represented by Formula 2 is the same as in Schemes 1 to 5.

Scheme 1: Y is -C≡C-

After attaching a substituent to a meta position using a base and an alkyl halide, etc., a Pd coupling reaction is performed to form a tolane structure.

[Scheme 2: When Y is -O-, -NR _3- , -S-]

Scheme 3: Y is a single bond,-(CH ₂ ) _q- , -CH = CH-, -C (= O)-

From the nucleophilic substitution reaction, Y can make a compound which is a single bond, (CH ₂ ) _q , CH = CH, or CO.

Scheme 4: When Y is -C (= 0) O-

[Scheme 5: When Y is -OC (= O)-]

The CO ₂ gas may be bubbled to form a CO ₂ H group, and an OH group may be introduced using (Me ₃ SiO) ₂ . In addition, ester compounds are prepared by using SOCl ₂ , COCl ₂ , MsCl, TsCl, EDC [1-Ethyl-3- (3-dimethyl aminopropyl) carbo diimide hydrochloride], or DCC (dicyclohexylcarbodiimide), or An esterification reaction may be performed using Dean-Stark.

In Reaction Schemes 1 to 5, M is a metal capable of making anions such as Li, Na, Mg, K, Ca, or Cs. BuLi, NaH, NaOH, NaHCO ₃ , Na ₂ CO ₃ , Mg, K ₂ CO ₃ , KOH , CaH, Cs ₂ CO ₃ Or organic salts such as amines. P also means a protection group.

The reaction schemes are only exemplary methods, and the method for preparing the compound represented by Chemical Formula 2 may be prepared by the method according to the above-described schemes 1 to 5 as well as the preparation method by a similar route.

Multifunctional Crosslinking agent

It is preferable that the acrylic adhesive composition which concerns on this invention contains a polyfunctional crosslinking agent further.

The multifunctional crosslinking agent may be one or more selected from the group consisting of an isocyanate compound, an epoxy compound, an aziridine compound, and a metal chelate compound, and more preferably an isocyanate compound.

Examples of the isocyanate-based crosslinking agent include tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoform diisocyanate, tetramethylxylene diisocyanate, naphthalene diisocyanate, and polyols such as trimethylolpropane. One or more selected from the group consisting of reactants can be used.

Examples of the epoxy-based crosslinking agent include ethylene glycol diglycidyl ether, triglycidyl ether, trimethol propane triglycidyl ether, N, N, N'N'-tetraglycidyl ethylenediamine, and glycerin diglycidyl. One or more selected from the group consisting of ethers can be used.

Examples of the aziridine-based crosslinking agent include N, N'-toluene-2,4-bis (1-aziridinecarboxide), N, N'-diphenylmethane-4,4'-bis (1-aziridinecarbox Id), triethylenemelamine, bisisoprotaloyl-1- (2-methylaziridine), and at least one selected from the group consisting of tri-1-aziridinylphosphine oxide can be used.

As the metal chelate crosslinking agent, at least one selected from the group consisting of compounds in which polyvalent metals such as aluminum, iron, zinc, tin, titanium, antimony, magnesium, vanadium and the like are coordinated with acetylacetone or ethyl acetoacetate may be used. .

The content of the multifunctional crosslinking agent is preferably 0.01 to 5 parts by weight based on 100 parts by weight of the acrylic copolymer containing the aromatic group (A). When the content is less than 0.01, the crosslinking degree of the pressure-sensitive adhesive is low, and durability worsens.

The multifunctional crosslinking agent may be uniformly coated only when the crosslinking reaction by the functional group of the crosslinking agent hardly occurs in the process of blending for forming the acrylic pressure sensitive adhesive composition and the adhesive layer. After the coating operation is finished and the drying and aging process, a crosslinked structure is formed to obtain an adhesive layer having a strong elasticity and cohesion.

additive

In addition, the acrylic pressure-sensitive adhesive composition of the present invention may further include a silane coupling agent in order to improve the adhesive stability by adhesion to the glass plate to further improve the heat and moisture resistance characteristics.

The silane coupling agent serves to improve the adhesion reliability, especially when left for a long time under high temperature and high humidity, the content may be used in 0.005 to 5 parts by weight based on 100 parts by weight of the acrylic copolymer (A) containing an aromatic group. If the content is less than 0.005 parts by weight, there is no improvement in adhesion reliability, and if the content is more than 5 parts by weight, durability is poor.

Examples of the silane coupling compound include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, 3-mercapto propyl trimethoxy group silane, Vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxy Silane, 3-isocyanatepropyltriethoxysilane, or γ-acetoacetatepropyltrimethoxysilane, and the like, and these may be used alone or in combination.

In addition, the acrylic pressure-sensitive adhesive composition of the present invention may include a tackifying resin in order to control the adhesive performance, the content thereof may be used in the range of 1 to 100 parts by weight based on 100 parts by weight of the acrylic copolymer (A) containing an aromatic group. have.

Excessive use of the tackifying resin can reduce the compatibility or cohesion of the pressure-sensitive adhesive and should be added appropriately.

The tackifying resin is (hydrogenated) hydrocarbon resin, (hydrogenated) rosin resin, (hydrogenated) rosin ester resin, (hydrogenated) terpene resin, (hydrogenated) terpene phenol resin, polymeric rosin resin, or polymeric rosin ester resin Etc., and these can be used individually or in mixture of 2 or more types.

In addition, the present invention may be used by further mixing a plasticizer, an epoxy resin and a curing agent for a specific purpose, UV stabilizers, antioxidants, colorants, reinforcing agents, fillers, antifoaming agents, surfactants, antistatic agents, etc. according to the general purpose It can add and use suitably.

In addition, the present invention is a polarizing film; And a pressure-sensitive adhesive layer formed on one or both surfaces of the polarizing film and containing the acrylic pressure-sensitive adhesive composition according to the present invention.

The polarizing plate of this invention contains the adhesion layer formed from the said adhesive composition in one or both surfaces of a polarizing film, The polarizing film or polarizing element which comprises a polarizing plate is not specifically limited.

Preferably, the polarizing film includes, for example, a film obtained by adding a polarizing component such as iodine or a dichroic dye to a film made of polyvinyl alcohol-based resin and stretching, and the thickness of these polarizing films is also particularly limited. It is not possible to form a conventional thickness. At this time, the polyvinyl alcohol-based resin may be used polyvinyl alcohol, polyvinyl formal, polyvinyl acetal and ethylene, saponified vinyl acetate copolymer.

On both sides of the polarizing film, a cellulose film such as triacetyl cellulose (TAC); Polyester film such as polycarbonate film and polyethylene terephthalate; Polyether sulfone-based film; Or a multilayer film having a protective film such as a polyolefin-based film such as polyethylene, polypropylene, cyclo-based or norbornene structure, or a polyolefin-based film such as ethylene propylene copolymer. At this time, the thickness of these protective films is also not particularly limited, and may form a conventional thickness.

In the present invention, a method of forming an adhesive layer on the polarizing film is not particularly limited, and a method of applying and drying the pressure-sensitive adhesive using a bar coater or the like directly on the surface of the polarizing film, or by applying the pressure-sensitive adhesive on the surface of the peelable substrate once After drying, a method of transferring the pressure-sensitive adhesive layer formed on the surface of the peelable base material to the surface of the polarizing film and then aging may be applied.

In addition, the polarizing plate of the present invention may be laminated with one or more layers providing additional functions such as a protective layer, a reflective layer, an antiglare layer, a retardation plate, a wide viewing angle compensation film, and a brightness enhancement film.

The present invention also relates to a liquid crystal display device comprising a liquid crystal panel in which the polarizing plate is bonded to one side or both sides of liquid crystal color.

The polarizing plate to which the pressure-sensitive adhesive of the present invention is applied can be applied to all conventional liquid crystal display devices, and the kind of the liquid crystal panel is not particularly limited. Preferably, the present invention may comprise a liquid crystal display device including a liquid crystal panel in which the polarizing plate is bonded to one side or both sides of a liquid crystal cell.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, which are intended to help a specific understanding of the present invention, and the scope of the present invention is not limited to the Examples.

(A) Aromatic groups  Acrylic copolymer containing

<Manufacture example 1>

78 parts by weight of n-butylacrylate (n-BA), 20 parts by weight of benzyl acrylate, as shown in Table 1, in a 1 L reactor equipped with a refrigeration system to allow nitrogen gas to be refluxed and to facilitate temperature control. , 2-hydroxyethyl methacrylate (2-hydroxyethyl (metha) acrylate: 2-HEMA) A mixture of monomers composed of 2 parts by weight was added. Then, 120 parts by weight of ethylacetate (EAc) was added as a solvent. After purging nitrogen gas for 60 minutes to remove oxygen, the temperature was maintained at 60 ° C., and 0.03 parts by weight of azobisisobutyronitrile (AIBN), which was a reaction initiator, was reacted for 8 hours. After the reaction, the mixture was diluted with ethyl acetate (EAc) to prepare an acrylic copolymer containing an aromatic group having a solid content of 20% by weight and a weight average molecular weight of 1.5 million.

<Production Examples 2 to 6>

In Preparation Example 1, as shown in Table 1, a part of each component was not added or partially added to prepare an acrylic copolymer containing a high molecular weight aromatic group. The results are shown in Table 1 below.

sign Furtherance
ingredient Manufacturing example One 2 3 4 5 6 Copolymer composition Ⅰ) n-BA 78 90 53 96 58 98 Ⅰ) MA 15 Ii) BzA 20 5 2 Ii) PHEA 35 40 Ⅲ) 2-HEMA 2 2 2 2 2 Ⅲ) AA 5 Initiator AIBN 0.03 0.03 0.03 0.03 0.03 0.03 menstruum EAC 120 110 150 120 120 120 Weight average molecular weight (only) 150 160 120 150 150 150 n-BA: n-butyl acrylate
MA: methyl acrylate
BzA: benzyl acrylate
PHEA: Phenoxyethylacrylate
2-HEMA: 2-hydroxyethyl methacrylate
AA: acrylic acid
AIBN: azobisisobutyronitrile
EAc: ethyl acetate (unit: parts by weight)

(B) Mesogen Meta  An alkyl group at the position, Alkenyl groups  or Alkynyl groups  Optics with one or more substituents containing Anisotropy  compound

<Manufacture example 7>

1.0 equivalent of Compound 1 was dissolved in a mixed solvent of ethanol: water = 7: 3, and then 1.0 equivalent of bromohexane and 2.2 equivalents of KOH were added thereto, and the mixture was stirred at 90 ° C. for about 10 hours. Ethanol was distilled under reduced pressure to completely remove it, and then additional water was added thereto. 10% HCl (aq) was slowly added thereto to adjust the pH between 1 and 3 to obtain Compound 2 in a yield of 90% or more. 1.0 equivalent of Compound 2 and 1.0 equivalent of Compound 3 were dissolved in CH ₂ Cl ₂ . 1.2 equivalent of EDC and 0.1 equivalent of DMAP were added thereto, followed by stirring at room temperature for about 10 hours. After completion of the reaction, the product was worked up with CH ₂ Cl ₂ and purified by silica gel to give the final compound 4 in a yield of 88% or more. ¹ HNMR This was confirmed. ¹ HNMR (400 MHz, CDCl ₃ ): δ 0.93 (t, 3H), 1.29-1.45 (m, 4H), 1.46-1.57 (m, 2H), 1.78-1.89 (m, 2H), 4.05 (t, 2H) , 7.20 (dd, 1H), 7.35 (d, 2H), 7.43 (t, 1H), 7.67 (d, 2H), 7.69-7.80 (m, 5H), 7.83 (d, 1H).

<Manufacture example 8>

1.0 equivalent of Compound 1 was dissolved in a mixed solvent of ethanol: water = 7: 3, and then 1.0 equivalent of 2-ethylnuxyl bromide (5) and 2.2 equivalent of KOH were added and stirred at 90 ° C. for 10 hours. Ethanol was distilled under reduced pressure to completely remove it, and then additional water was added thereto. To this was slowly added 10% HCl (aq) to adjust the pH between 1 to 3 to produce alkoxybenzoic acid in a yield of 90% or more. 1.0 equivalent of this benzoic acid compound and 1.0 equivalent of Compound 3 were dissolved in CH ₂ Cl ₂ . 1.2 equivalent of EDC and 0.1 equivalent of DMAP were added thereto, followed by stirring at room temperature for about 10 hours. After the reaction work in CH ₂ Cl ₂ - up (work-up), and purified by silica gel to give a final compound 6 in over 85% yield. ¹ HNMR This was confirmed. ¹ HNMR (400 MHz, CDCl ₃ ): δ 0.90 to 0.97 (m, 6H), 1.29 to 1.38 (m, 4H), 1.38 to 1.61 (m, 4H), 1.69 to 1.81 (m, 1H), 3.94 (dd, 2H), 7.21 (dd, 1H), 7.34 (d, 2H), 7.42 (t, 1H), 7.66 (d, 2H), 7.68-77.7 (m, 5H), 7.80 (d, 1H).

<Manufacture example 9>

1.0 equivalent of Compound 7 and 1.0 equivalent of Compound 8 were dissolved in a mixed solvent of Dioxane: DMF = 9: 1, followed by 2.0 equivalents of Cs ₂ CO ₃ , 0.1 equivalents of CuI and 0.1 equivalents of 1,1,1- Tris (hydroxymethyl) ethane (1,1,1-tris (hydroxymethyl) ethane) was added thereto and stirred at 110 ° C for 20 hours. After completion of the reaction, work-up was performed using ether and water and purified using silica gel to obtain Compound 9 in a yield of about 90%. ¹ HNMR This was confirmed. ¹ HNMR (400 MHz, CDCl ₃ ): δ 0.93 (t, 3H), 1.48-1.63 (m, 2H), 2.30 (t, 3H), 7.02-7.53 (m, 6H), 7.65 (d, 2H), 7.69 ~ 7.74 (m, 4 H).

Production Example 10

1.0 equivalent of Compound 9 was dissolved in CH ₂ Cl ₂ solvent and then slowly added 2.2 equivalents of m-CPBA (m-chloroperbenzoic acid) at 0 ° C. After 30 minutes of stirring at room temperature, work-up and purification with silica gel gave Compound 10 in 80% yield. In this case, when 1.0 equivalent of m-CPBA was used instead of 2.2 equivalents, sulfoxide compound 11 was formed. ¹ HNMR This was confirmed. ¹ HNMR (400 MHz, CDCl ₃ ): δ 0.93 (t, 3H), 1.48-1.63 (m, 2H), 2.30 (t, 3H), 7.18-7.22 (m, 2H), 7.63 (d, 2H), 7.65 ~ 7.70 (m, 4H), 7.99-8.05 (m, 4H).

Production Example 11

1.0 equivalent of Compound 12 was dissolved in butanone, and then 1.2 equivalents of hexylbromide and 1.2 equivalents of K ₂ CO ₃ were added and stirred at 80 ° C. for about 5 hours. After completion of the reaction, work-up with ether and purification with silica gel gave Compound 13 in a yield of 90% or more. Compound 14 may be prepared by using SOCl ₂ and TEA in an acid compound (Compound 19 below) which is a conventional method. 1.0 equivalent of Compound 13 and 1.0 equivalent of Compound 14 were dissolved in a benzene-free solvent, added with a NiCl ₂ (PPh ₃ ) ₂ catalyst, and stirred at room temperature for 2 hours, followed by work-up using water and ether. up) and silica gel column chromatography to obtain the final compound 15 in about 70% yield. ¹ HNMR This was confirmed. ¹ HNMR (400 MHz, CDCl ₃ ): δ 0.98 (t, 3H), 1.30-1.45 (m, 4H), 1.45-1.59 (m, 2H), 1.80-1.89 (m, 2H), 4.05 (t, 2H) , 7.21-7.60 (m, 9H), 7.87 (s, 1H), 7.92 (m, 3H).

Production Example 12

1.0 equivalent of Compound 16 was dissolved in THF, and then 1.0 equivalent of TBSCl (tert-butyldimethylsilyl chloride) and 1.2 equivalent of imidazole were added and stirred at 80 ° C. for about 5 hours. After completion of the reaction, the resulting salt was filtered off and purified by silica gel to prepare compound 17 in a yield of 80%. Compound 17 was dissolved in butanone, and 1.2 equivalents of hexylbromide and 1.2 equivalents of K ₂ CO ₃ were added and stirred at 80 ° C. for 10 hours. After completion of the reaction, work-up with ether, purified with silica gel, dissolved in THF, and 1.1 equivalent of TBAF were added to perform deprotection. After stirring for about 1 hour at room temperature work-up with ether (purified) and purified by silica gel to give compound 18. After 1.0 equivalent of Compound 18 and 1.0 equivalent of Compound 19 were dissolved in CH ₂ Cl ₂ , 1.2 equivalents of EDC and 0.1 equivalents of DMAP were added and stirred at room temperature for 10 hours. After completion of the reaction, work-up with CH ₂ Cl ₂ and purification with silica gel gave Compound 20 in a yield of 85%. ¹ HNMR This was confirmed. ¹ HNMR (400 MHz, CDCl ₃ ): δ 0.97 (t, 3H), 1.29-1.44 (m, 4H), 1.45-1.57 (m, 2H), 1.78-1.89 (m, 2H), 4.03 (t, 2H) , 7.22-7.56 (m, 9H), 7.60 (d, 1H), 7.88 (d, 1H), 8.11 (d, 2H).

Production Example 13

Dissolve 1.0 equivalent of m-bromophenol (compound 21) in butanone, add 1.2 equivalent of bromobutane and 1.2 equivalent of K ₂ CO ₃ at 80 ° C for 5 hours. Stirred. After completion of the reaction, work-up was performed using ether and water and purified using silica gel to obtain Compound 22 in a yield of about 95%. 1.0 equivalent of compound 22 and 1.0 equivalent of trimethylsilylacetylene, 0.1 equivalent of CuI, 0.03 equivalent of PdCl ₂ (PPh ₃ ) ₂ and 4.0 equivalent of triethylamine were dissolved in benzene and 60 Stir at about 10 hours. After completion of the reaction, work-up was performed using ether and water and purified using silica gel to obtain Compound 23 in a yield of about 90%. 1.0 equivalent of Compound 23 and 1.0 equivalent of Compound 24, 0.1 equivalent of CuI, 0.03 equivalent of PdCl ₂ (PPh ₃ ) ₂ , 6.0 equivalent of DBU and 1.0 equivalent of H ₂ O were dissolved in benzene and at 60 ° C. Stir for about 10 hours. After completion of the reaction, work-up was performed using ether and water and purified using silica gel to obtain the final compound 25 in a yield of about 85%. ¹ HNMR This was confirmed. ¹ HNMR (400 MHz, CDCl ₃ ): δ 1.06 (t, 3H), 1.73 to 1.92 (m, 4H), 4.07 (t, 2H), 7.17 (d, 1H), 7.22 (d, 1H), 7.25 to 7.30 (m, 3 H), 7.47 (m, 3 H), 7.68 (s, 1 H).

Production Example 14

Synthesis was carried out in the same manner as in Preparation Example 7, except that Compound 26 was used instead of Compound 1 to synthesize Compound 27 having a substituent at the para position.

Example  One

<Mixing>

Tolylene diisocyanate adduct of isocyanate trimethylolpropane as a polyfunctional crosslinking agent after uniformly mixing 100 parts by weight (solid content) of the high molecular weight acrylic copolymer obtained in Preparation Example 1 and 3 parts by weight of the optically anisotropic compound obtained in Preparation Example 7. 0.1 parts by weight and γ-glycidoxypropyltrimethoxysilane were added thereto, and diluted to an appropriate concentration in consideration of coating properties, uniformly mixed, coated on a release paper, dried, and a 25 micron uniform adhesive layer was obtained. .

<Plywood process>

The adhesion layer obtained above was adhesive-processed to the 185 micron-thick iodine type polarizing plate, and it aged at room temperature for 7 days.

Example  2 to 7

Based on the formulation of Example 1 as shown in Table 2 and Table 3, the acrylic copolymer containing the aromatic group prepared through Preparation Examples 1 to 6 and the optically anisotropic compound and the crosslinking agent prepared through Preparation Examples 7 to 14 The compounding and plywood processes were performed in the same manner as in Example 1.

Comparative example  1 to 6

As shown in Table 3 below, by mixing or partially blending a part of the formulation of Example 1, the acrylic copolymer was blended and plywooded in the same manner as in Example 1.

Test Example

In order to evaluate the properties of the pressure-sensitive adhesive compositions prepared in Examples 1 to 7 and Comparative Examples 1 to 6, the following test items were reviewed and the results are shown in Tables 2 and 3 below.

1. Compatibility

After coating and drying the adhesive on the release film, it was confirmed that the adhesive became cloudy due to poor compatibility. After the adhesive was attached to the polarizing plate, the optical anisotropy was preserved at room temperature, low temperature (-20 ° C), and high temperature (50 ° C) for 6 months. Determine if crystallization of the compound occurs

2. Endurance Reliability

The pressure-sensitive adhesive coated polarizing plate (90 mm x 170 mm) prepared in Examples and Comparative Examples was attached to a glass substrate (110 mm x 190 mm x 0.7 mm) in a state where the optical absorption axis was crossed on both sides. At this time, the applied pressure was about 5㎏ / ㎠ to clean the room so that no bubbles or foreign matter. The specimens were left for 1000 hours at 60 ° C. and 90% relative humidity to observe the heat and moisture resistance. The heat resistance was observed for 1000 hours at the temperature of 80 ℃ after the occurrence of bubbles or peeling. Immediately after evaluating the state of the specimen was performed at room temperature for 24 hours. The evaluation criteria for reliability are as follows.

○: no bubbles or peeling

△: slight bubble or peeling phenomenon

×: large amount of bubbles and peeling phenomenon

3. Light transmission uniformity (light leakage)

In order to investigate the uniformity of the light transmittance using the same specimen as described above, it was observed whether the light leaked out of the dark room using the backlight. As a method of testing the light transmittance uniformity, the coated polarizing plate (200 mm x 200 mm) was intersected 90 degrees to the glass substrate (210 mm x 210 mm x 0.7 mm) and attached to both sides. The uniformity of light transmittance was evaluated based on the following criteria.

⊙: Unevenness of light transmittance is hard to judge

○: slight light transmittance nonuniformity

△: non-uniformity of light transmittance

X: The light non-uniformity is abundant.

Example One 2 3 4 5 6 (A) Acrylic Copolymer Preparation Example 1 100 100 Production Example 2 100 100 Production Example 3 100 100 (B) optically anisotropic compound Preparation Example 7 3 Preparation Example 8 20 Preparation Example 9 0.5 Preparation Example 10 15 Preparation Example 11 5 Production Example 12 2 Crosslinking agent 0.1 0.1 0.1 0.1 0.1 0.1 Compatibility Good Good Good Good Good Good Durability Reliability ○ ○ ○ ○ ○ ○ Light transmission uniformity (light leakage) ⊙ ⊙ ⊙ ⊙ ⊙ ⊙

Example Comparative example 7 One 2 3 4 5 6 (A) Acrylic Copolymer Preparation Example 1 100 100 100 Production Example 2 100 Preparation Example 4 100 Preparation Example 5 100 Preparation Example 6 100 (B) optically anisotropic compound Preparation Example 7 One One Preparation Example 8 0.2 25 Preparation Example 13 5 Preparation Example 14 5 Crosslinking agent 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Compatibility Good Good Good Good Good Good crystallization Durability Reliability ○ ○ ○ ○ ○ ○ × Light transmission uniformity (light leakage) ⊙ × △ △ △ △ ×

As shown in the results of Table 2 and Table 3, it can be seen that in Examples 1 to 7 of the present invention, excellent compatibility, durability, light transmission uniformity (light leakage characteristics) are exhibited. On the other hand, when the optically anisotropic compound is not added as in Comparative Example 1, it is understood that light leakage appears due to poor light transmittance uniformity, and in Comparative Example 2, the content of the optically anisotropic compound used in the present invention is excellent. It can be seen that there is not enough performance to satisfy the light transmittance uniformity. In the case of Comparative Example 3 it can be seen that the positive birefringence of the pressure-sensitive adhesive under the residual stress is increased by using an excess optically anisotropic compound, rather the light leakage is stronger. In the case of Comparative Example 4 it can be seen that the light leakage appears because the content of the aromatic acrylic ester is small, in the case of Comparative Example 5 the amount of the aromatic acrylic ester is used in excess, the positive birefringence of the adhesive under severe residual stress rather light It turns out to be stronger. In Comparative Example 6, when a compound having a substituent was added to the para position prepared in Preparation Example 14, an excessive amount of crystallization occurred in the pressure-sensitive adhesive layer, indicating that durability and light transmission uniformity were poor.

Claims (26)

(A) an acrylic copolymer containing an aromatic group; And (B) Acrylic adhesive composition for polarizing plates containing the optically anisotropic compound which has one or more substituents containing an alkyl group, an alkenyl group, or an alkynyl group in the meta position of mesogen. The method of claim 1, (A) The acrylic copolymer containing an aromatic group includes: (i) a (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms; Ii) an aromatic group-containing acrylic monomer copolymerizable with the alkyl (meth) acrylic acid ester monomer; And iii) a crosslinkable functional group-containing monomer. The method of claim 2, (Iii) The (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms is methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, butyl ( Meta) acrylate, t-butyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, It is 1 or more types chosen from the group which consists of isooctyl (meth) acrylate and isononyl (meth) acrylate, The acrylic adhesive composition for polarizing plates characterized by the above-mentioned. The method of claim 2, Iii) The content of the (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms is 55 to 95 parts by weight, the acrylic pressure-sensitive adhesive composition for polarizing plates. The method of claim 2, Ii) The aromatic group-containing acrylic monomer is an acrylic pressure-sensitive adhesive composition for a polarizing plate, characterized in that the compound represented by the following formula (1): [Formula 1]

Where R ₁ is hydrogen or a methyl group, R ₂ is an alkylene group having 1 to 12 carbon atoms, n is an integer from 0 to 3, X is oxygen, sulfur or an alkylene group having 1 to 4 carbon atoms, Ar is an aromatic group unsubstituted or substituted with halogen or alkyl having 1 to 12 carbon atoms. The method of claim 5, The compound represented by the formula (1) is phenoxy ethyl (meth) acrylate, benzyl (meth) acrylate, 2-phenylthio-1-ethyl (meth) acrylate, 6- (4,6-dibromo-2- Isopropyl phenoxy) -1-hexyl (meth) acrylate, 6- (4,6-dibromo-2-sec-butyl phenoxy) -1-hexyl (meth) acrylate, 2,6-dibro Mono-4-nonylphenyl (meth) acrylate, 2,6-dibromo-4-dodecyl phenyl (meth) acrylate, 2- (1-naphthyloxy) -1-ethyl (meth) acrylate, 2- (2-naphthyloxy) -1-ethyl (meth) acrylate, 6- (1-naphthyloxy) -1-hexyl (meth) acrylate, 6- (2-naphthyloxy) -1- Hexyl (meth) acrylate, 8- (1-naphthyloxy) -1-octyl (meth) acrylate, and 8- (2-naphthyloxy) -1-octyl (meth) acrylate It is 1 or more types, The acrylic adhesive composition for polarizing plates. The method of claim 2, Ii) The content of the aromatic group-containing acrylic monomer is an acrylic pressure-sensitive adhesive composition for a polarizing plate, characterized in that 5 to 35 parts by weight. The method of claim 2, Iii) The crosslinkable functional group-containing monomer is at least one member selected from the group consisting of hydroxyl group-containing monomers, carboxyl group-containing monomers, and nitrogen-containing monomers. The method of claim 2, Iii) The content of the crosslinkable functional group-containing monomer is 0.1 to 10 parts by weight of the acrylic pressure-sensitive adhesive composition for polarizing plates. The method of claim 1, (A) The acrylic copolymer containing an aromatic group has a weight average molecular weight of 800,000-2 million, The acrylic adhesive composition for polarizing plates characterized by the above-mentioned. The method of claim 1, Acrylic copolymers containing (A) aromatic groups include styrene, alpha methyl styrene, vinyl acetate, acrylonitrile, (meth) acrylamide, N-methyl (meth) acrylamide, and N-butoxy methyl (meth) acrylamide Acrylic pressure-sensitive adhesive composition for a polarizing plate, characterized in that it further comprises at least one copolymerization monomer selected from the group consisting of. The method of claim 1, (B) the optically anisotropic compound having at least one substituent containing an alkyl group, an alkenyl group, or an alkynyl group in the meta position of mesogen is a compound represented by the following formula (2): acrylic pressure-sensitive adhesive composition for a polarizing plate: [Formula 2]

Where

Is

or

ego;

Is

or

Is;

Is

or

ego; Z is C-W or N; Q ₁ to Q ₁₅ , and W are each independently hydrogen, halogen, cyano, —R ₅ , —OR ₅ , —NHR ₅ , —NR ₅ R ₅ or —C (═O) R ₅ ; l, m and n are each independently an integer of 0 to 3, and l + m + n is an integer of 1 or more; Y, G ₁ , G ₂ , X ₁ and X ₂ are each independently a single bond, -O-, -NR _5- , -S-, -SO-, -SO _2- , alkylene of C ₁ to C ₆ , C ₂ to C ₆ alkenylene, C ₂ to C ₆ alkynylene, or -UTV-, Where -T- is carbonyl (-C (= O)-), U and V are each a single bond, -O-, -NR _5- , -S-,-(CH ₂ ) _p- , -O ( CH ₂ ) _p -,-(CH ₂ ) _p O-, p is an integer from 1 to 5, E is hydrogen, halogen, cyano, -NCO, -NCS, -R ₅ , or -OR ₅ ; R ₃ , R ₄ and R ₅ are each independently hydrogen, C ₁ to C ₂₀ alkyl unsubstituted or substituted with one or more halogens, C ₂ to C ₂₀ eggs unsubstituted or substituted with one or more halogens. Alkenyl, C ₂ to C ₂₀ alkynyl substituted or unsubstituted with one or more halogens, or — (R ₆ O) _q R ₇ , wherein R ₆ is C ₁ to C ₆ alkylene R ₇ is C ₁ to C ₄ alkyl, q is an integer from 1 to 5, but R ₃ and R ₄ Does not include the case where is hydrogen at the same time. 13. The method of claim 12, Y, G ₁ , and G ₂ of the compound represented by Formula 2 are each independently a single bond, -O-, -NR _3- , -S-, -SO-, -SO ₂ -,-(CH ₂ ) _p -, -CH = CH-, -C≡C-, -C (= O) O-, -OC (= O)-, -C (= O)-, -C (= O) NR ₃ -,- NR ₃ C (= 0)-, -C (= 0) S-, -SC (= 0)-, -C (= 0) O (CH ₂ ) _p- , -OC (= 0) (CH ₂ ) _p -,-(CH ₂ ) _p OC (= O)-, or-(CH ₂ ) _p C (= O) O-, p is an integer of 1 to 5, the acrylic pressure-sensitive adhesive composition for polarizing plates. 13. The method of claim 12, G ₁ and G ₂ of the compound represented by Formula 2 are each independently a single bond, -CH = CH- or -C≡C-, acrylic pressure-sensitive adhesive composition for a polarizing plate. 13. The method of claim 12, X ₁ and X ₂ of the compound represented by Formula 2 are each independently a single bond, -O-, -NR _5- , -S-, -SO-, -SO ₂ -,-(CH ₂ ) _p -,- C (= 0) NR _5- , -NR ₅ C (= 0)-, -NR ₅ C (= 0) NR _5- , -C (= 0) O-, -OC (= 0)-, or- OC (= O) O-, p is an integer of 1-2, The acrylic adhesive composition for polarizing plates characterized by the above-mentioned. 13. The method of claim 12, Linear or branched C ₃ to C ₁₂ alkyl, C ₃ to C ₁₂ alkenyl, C ₃ to C ₁₂ of R ₃ and R ₄ of the compound represented by the formula (2) are unsubstituted or substituted with one or more halogens. It is an alkynyl acryl-type adhesive composition for polarizing plates. 13. The method of claim 12, R ₃ , R ₄ and R ₅ of the compound represented by Formula 2 are each independently-(CH ₂ CH ₂ O) _q CH ₃ ,-(CH ₂ CHCH ₃ O) _q CH ₃ , or-(CHCH ₃ CH ₂ O) _q CH ₃ , q is an integer of 1 to 5, the acrylic pressure-sensitive adhesive composition for a polarizing plate. The method of claim 1, (B) The content of the optically anisotropic compound having at least one substituent containing an alkyl group, alkenyl group or alkynyl group in the meta position of mesogen is 0.5 to 20 parts by weight based on 100 parts by weight of the acrylic copolymer containing (A) an aromatic group. Acrylic adhesive composition for polarizing plates characterized by the above-mentioned. The method of claim 1, An acrylic pressure sensitive adhesive composition for polarizing plates, further comprising a multifunctional crosslinking agent. The method of claim 19, The polyfunctional crosslinking agent is at least one member selected from the group consisting of an isocyanate compound, an epoxy compound, an aziridine compound, and a metal chelate compound. The method of claim 19, The content of the polyfunctional crosslinking agent is (A) 0.01 to 5 parts by weight based on 100 parts by weight of the acrylic copolymer containing an aromatic group, the acrylic pressure-sensitive adhesive composition for polarizing plates. The method of claim 1, (A) The acrylic pressure-sensitive adhesive composition for polarizing plates, further comprising 0.005 to 5 parts by weight of a silane coupling agent based on 100 parts by weight of the acrylic copolymer containing an aromatic group. The method of claim 1, (A) 1 to 100 parts by weight of the tackifier resin with respect to 100 parts by weight of the acrylic copolymer containing an aromatic group, further comprising an acrylic pressure-sensitive adhesive composition for a polarizing plate. Polarizing film; And It is formed on one side or both sides of the said polarizing film, The polarizing plate containing the adhesive layer containing the acrylic adhesive composition in any one of Claims 1-23. The method of claim 24, The polarizing plate comprises at least one layer selected from the group consisting of a protective layer, a reflective layer, a retardation plate, a wide viewing angle compensation film and a brightness enhancing film. A liquid crystal display device comprising a liquid crystal panel obtained by bonding the polarizing plate of claim 24 to one or both surfaces of a liquid crystal cell.