KR20120078020A - Acrylic adhesive composition - Google Patents

Abstract

PURPOSE: An acrylic adhesive composition is provided to improve light leakage phenomenon, and to have excellent thermal resistance, and to have high release strength, thereby capable of restraining excitation phenomenon. CONSTITUTION: An acrylic adhesive composition comprises an acrylic copolymer comprising a monomer having a pyrrolidonyl group, and a hardener. The comprised amount of the monomer having pyrrolidonyl group is 11-40 parts by weight in 100.0 parts by weight of the acrylic copolymer. The acrylic copolymer is polymerized of 60-83 parts by weight of (meth)acrylic acid alkyl ester having an alkyl group, 1-10 parts by weight of (meth)acrylic ester having a hydroxy group, and 11-40 parts by weight of a monomer having a pyrrolidonyl group. The acrylic copolymer additionally comprises a silane group. The weight average molecular weight of the acrylic copolymer is 800,000-1,500,000 g/mol.

Description

Acrylic Adhesive Composition

The present invention relates to an acrylic pressure-sensitive adhesive composition. More specifically, the present invention relates to an acrylic pressure-sensitive adhesive composition having a light leakage improvement effect by including a pyrrolidoneyl group in the acrylic copolymer.

The polarizing plate is an optical member included in a liquid crystal display (LCD). The polarizing plate includes an iodine compound or a dichroic polarizing material arranged in a predetermined direction. The polarizing plate has a multilayer structure in which a polarizing film or a protective film for protecting an element is formed on both surfaces.

Each film constituting the multilayered polarizing plate is made of a material having a molecular structure and composition of a different structure. Thus exhibiting different physical properties. In particular, when used for a long time under high temperature or high humidity conditions, the internal stress generated by the dimensional change of the optical film is concentrated in the peripheral portion as compared to the central portion of the optical film, the light leakage phenomenon occurs that the peripheral portion of the liquid crystal element is brighter than the central portion.

In order to improve such light leakage, designs of various pressure-sensitive adhesive compositions have been proposed. By using an acrylic pressure-sensitive adhesive binder composed only of alkyl groups with butyl acrylate as a main component of the pressure-sensitive adhesive binder, a composition for maximizing stress relaxation has been proposed. That is, it is the method of making the molecular weight of an acryl-type binder 1.5 million-2 million g / mol, and ensuring the flexibility of a coating film to the maximum using a small amount of thermosetting agents. However, the pressure-sensitive adhesive binder composed only of such alkyl groups has a problem that the light leakage phenomenon cannot be completely improved under heat or wet heat conditions.

Moreover, it is common that the existing adhesive composition for polarizing films contains an acrylic adhesive binder, an isocyanate type thermosetting agent, and a silane coupling agent. Silane coupling agents are used to improve adhesion to glass. However, when using trace amounts of silane coupling agents, mistakes can occur in mixing. In addition, when stirring is not easy, a problem may occur in that the adhesive force is not uniform after the polarizing film is formed.

An object of the present invention is to provide a pressure-sensitive adhesive composition having an effect of improving light leakage.

Another object of the present invention is to provide an adhesive composition having improved heat resistance.

Another object of the present invention to provide a pressure-sensitive adhesive composition that can solve the problems caused from the silane coupling agent in the production of the pressure-sensitive adhesive composition.

Still another object of the present invention is to provide a polarizing film including the pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition of the present invention

Acrylic copolymer containing the monomer which has a pyrrolidoneyl group; And

A monomer including a curing agent and having a pyrrolidoneyl group may be included in an amount of 11 to 40 parts by weight in 100 parts by weight of the acrylic copolymer.

In one embodiment, the acrylic copolymer may be a copolymer of a polymer having a (meth) acrylic acid alkyl ester having an alkyl group, a (meth) acrylic acid ester having a hydroxyl group and a monomer having a pyrrolidoneyl group.

In one embodiment, the acrylic copolymer may be further polymerized monomer having a silane group.

In one embodiment, the acrylic copolymer may be further polymerized monomer having a carboxyl group.

In one embodiment, monomers having silane groups can be introduced into the main chain of the acrylic copolymer by an isocyanate moiety.

In one embodiment, the pressure-sensitive adhesive composition may further comprise a silane compound.

In one embodiment, the weight average molecular weight of the acrylic copolymer may be 800,000-1,500,000 g / mol.

In one embodiment, the polydispersity of the acrylic copolymer may be 1-5.

The polarizing film of this invention may contain the said adhesive composition.

The present invention improves the light leakage phenomenon that is a problem in the polarizing film and provided a pressure-sensitive adhesive composition excellent in heat resistance. Moreover, this invention provided the adhesive composition which is high in peeling strength, does not have re-peeling, and suppresses lifting phenomenon. In addition, the present invention solves the nonuniformity in adhesion that may occur when the silane coupling agent is used separately.

The pressure-sensitive adhesive composition of the present invention is an acrylic copolymer containing a monomer having a pyrrolidoneyl group; And including a curing agent, the monomer having a pyrrolidoneyl group may be included in 11 to 40 parts by weight of 100 parts by weight of the acrylic copolymer.

The monomer having a pyrrolidoneyl group may include, for example, N-vinylpyrrolidone, but is not limited thereto.

The monomer having a pyrrolidoneyl group may be included in an amount of 11-40 parts by weight of 100 parts by weight of the acrylic copolymer. When included in less than 11 parts by weight, a problem that is somewhat insufficient to improve the light leakage improvement occurs in the polarizing adhesive film. When included in more than 40 parts by weight, the problem that the initial adhesive strength is lowered due to the high glass transition temperature (Tg) of the monomer having a pyrrolidoneyl group occurs. Preferably it may be included in 20-30 parts by weight of 100 parts by weight of the acrylic copolymer.

The acrylic copolymer may include one or more alkyl groups, one or more hydroxy groups, and one or more pyrrolidinyl groups.

There is no restriction | limiting in particular in the arrangement order of an alkyl group, a hydroxyl group, and a pyrrolidoneyl group in an acryl-type copolymer, It can change suitably. In addition, in the acrylic copolymer, the alkyl group, the hydroxy group or the pyrrolidoneyl group may each be continuously arranged.

The acrylic copolymer may be a copolymer obtained by copolymerizing a (meth) acrylic acid alkyl ester having an alkyl group, a (meth) acrylic acid ester having a hydroxyl group, and a monomer having a pyrrolidoneyl group, and the monomer having a pyrrolidoneyl group may be an acrylic It may be included in 11-40 parts by weight of 100 parts by weight of the copolymer.

The (meth) acrylic acid alkyl ester having an alkyl group may be included at 60-83 parts by weight, preferably 70-80 parts by weight of 100 parts by weight of the acrylic copolymer. Within this range, the initial adhesive force can be sufficiently exhibited so that the adhesion with the glass can be easily performed.

The acrylic copolymer may include two or more kinds of (meth) acrylic acid alkyl esters having different alkyl groups.

The (meth) acrylic acid alkyl ester having an alkyl group may include a (meth) acrylic acid alkyl ester having 1 to 20 carbon linear or branched alkyl groups in the ester moiety. For example, it may have a structure of Formula 1, but is not limited thereto. Specifically, the (meth) acrylic acid alkyl ester is methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, iso- Butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecylenate It may include, but is not limited to, one or more selected from the group consisting of sil (meth) acrylates and lauryl (meth) acrylates.

The (meth) acrylic acid ester having a hydroxyl group may mean a compound including a hydroxyl group in the terminal or ester structure and copolymerizable with the (meth) acrylic acid alkyl ester or N-vinylpyrrolidone. For example, the (meth) acrylic acid ester having the hydroxyl group may have a structure of Formula 2 below. Specifically, the (meth) acrylic acid ester having a hydroxyl group is 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl ( Meta) acrylate, 6-hydroxyhexyl (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, 1-chloro-2-hydroxypropyl (meth) acrylate, diethylene glycol mono (Meth) acrylate, 1,6-hexanediol mono (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, neopentyl glycol mono (meth) acrylate, Trimethylolpropane di (meth) acrylate, trimethylolethane di (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, 4-hydroxycyclohexyl (meth) acrylate, 2 Hydroxy-3 And at least one selected from the group consisting of -phenyloxy (meth) acrylate, 4-hydroxycyclohexyl (meth) acrylate, and cyclohexane dimethanol mono (meth) acrylate. Moreover, 2-hydroxyethyl (meth) acrylamide can be used instead of the (meth) acrylic acid ester which has a hydroxyl group.

The (meth) acrylic acid ester having a hydroxyl group may be included in 1-10 parts by weight, preferably 1-7 parts by weight of 100 parts by weight of the acrylic copolymer. In the above range, the crosslinking degree is excellent, there is no sliding phenomenon when the adhesive film is cut, and the phenomenon that the transition to the glass does not occur during rework has excellent initial adhesive force.

For example, the acrylic copolymer may be a copolymer obtained by copolymerizing monomers having the following Chemical Formulas 1, 2, and pyrrolidoneyl groups.

<Formula 1>

CH2 = CR-C (= O) O- (CH2) p-CH3

Wherein R is -H or-(CH2) n-CH3, n is an integer from 0-5,

p is an integer from 0-10)

<Formula 2>

CH2 = CR-C (= O) O- (CH2) q-OH

Wherein R is -H or-(CH2) n-CH3, n is an integer from 0-5,

q is an integer from 1-10)

The arrangement order of the monomer of Formulas 1 and 2 and the monomer having a pyrrolidoneyl group in the acrylic copolymer is not particularly limited and the same monomer may be continuously arranged.

Monomer of Formula 1: Monomer of Formula 2: The monomer having a pyrrolidoneyl group may be included in a molar ratio of 63-84: 3-8.5: 14-29. Preferably, the number of moles of the monomer of the general formula (1): the monomer of the general formula (2): a monomer having a pyrrolidoneyl group may be 69-82: 5-7: 15-24.

Within the range of the number of moles, the light leakage phenomenon can be improved, and a pressure-sensitive adhesive composition having excellent heat resistance and high peel strength and having no re-peelability and suppressing lifting phenomenon can be prepared.

The acrylic copolymer may further have at least one member selected from the group consisting of a silane group and a carboxyl group in addition to the alkyl group, the hydroxyl group and the pyrrolidoneyl group.

The monomer having a silane group may mean a monomer having a silane or a silane group and capable of bonding to a hydroxyl group of the (meth) acrylic acid ester having the hydroxyl group. The monomer having a silane group may have a structure of Formula 3 below.

<Formula 3>

(R2) (R3) (R4) Si- (CH2) s-R5

(Wherein R2, R3, and R4 are halogen or an alkoxy group having 1-5 carbon atoms, when s is 0, R5 is a vinyl group and when s is 1-10, R5 is NCO).

Preferably, the monomer having a silane group may further include an isocyanate group as well as a silane group. It may be connected to the main chain of the acrylic copolymer by the isocyanate group. More preferably, the monomer having a silane group may be included in the acrylic copolymer through the bonding of the isocyanate group and the hydroxyl group of the (meth) acrylic acid ester having a hydroxyl group.

The monomer having a silane group may be included in an amount of 1-5 parts by weight, preferably 1-2 parts by weight, based on 100 parts by weight of the acrylic copolymer. Within the above range, the polymerization stability is excellent, and the storage stability after the polymerization is also excellent.

For example, the acrylic copolymer may be a copolymer obtained by polymerizing the monomer having Formula 1, 2, pyrrolidonyl group and the monomer of Formula 3.

Formula 1: Formula 2: The monomer having a pyrrolidoneyl group: Formula 3 may be 59-85: 1-8.5: 14-30: 0.5-1.5. Within the mole ratio, the nonuniformity in adhesion that may occur when a silane compound, ie, a silane coupling agent, is used separately can be eliminated.

The acrylic copolymer may be polymerized with a (meth) acrylic acid alkyl ester having an alkyl group, a (meth) acrylic acid ester having a hydroxyl group, a monomer having a pyrrolidoneyl group and a monomer having a carboxyl group.

The monomer having a carboxyl group may have a structure of Formula 4 or 5.

&Lt; Formula 4 >

CH2 = CR-C (= O) O- (CH2) r-COOH

Wherein R is -H or-(CH2) n-CH3, n is an integer from 0-5,

r is an integer from 0 to 10)

<Formula 5>

CH2 = CR-C (= O) OH

(Wherein R is —H or — (CH 2) n —CH 3 and n is an integer from 0 to 5).

In the above, preferably r is an integer of 1-10.

The monomer having a carboxyl group may be included in an amount of 1-5 parts by weight, preferably 1-2 parts by weight, based on 100 parts by weight of the acrylic copolymer. Within the above range, the polymerization stability is excellent, and the storage stability after the polymerization is also excellent.

In another embodiment, the acrylic copolymer may have an alkyl group, a hydroxyl group, a pyrrolidoneyl group, a silane group and a carboxyl group. The arrangement order of the alkyl group, hydroxyl group, pyrrolidoneyl group, silane group and carboxy group is not particularly limited and may be appropriately changed. In the acrylic copolymer, the alkyl group, the hydroxyl group, the pyrrolidoneyl group, the silane group and the carboxyl group may each be continuously arranged.

The monomer having a silane group in the above may be included in 1-5 parts by weight, preferably 1-2 parts by weight based on 100 parts by weight of the acrylic copolymer. Within the above range, the polymerization stability is excellent, and the storage stability after the polymerization is also excellent.

The monomer having a carboxyl group may be included in 1-5 parts by weight, preferably 1-2 parts by weight, based on 100 parts by weight of the acrylic copolymer. Within the above range, the polymerization stability is excellent, and the storage stability after the polymerization is also excellent.

For example, the acrylic copolymer may be a copolymer obtained by polymerizing the monomer having Formula 1, 2, pyrrolidoneyl group, and the monomer of Formula 4 or 5. Formula 1: Formula 2: monomer having a pyrrolidoneyl group: Formula 4 or 5 may be 56-84: 1-8: 14-31: 1-4.5. Within the mole ratio, the nonuniformity in adhesion that may occur when a silane compound, ie, a silane coupling agent, is used separately can be eliminated.

The pressure-sensitive adhesive composition may include 94-99.8 parts by weight of the acrylic copolymer and 0.2-6 parts by weight of a curing agent.

The curing agent may be a thermal curing agent. For example, it may be one or more selected from the group consisting of isocyanate, epoxy, aziridine, melamine, amine, imide, carbodiimide and amide, but is not limited thereto. Isocyanate thermal curing agents are preferred.

Isocyanate-based thermal curing agents can be used conventional ones known to those skilled in the art. For example, isocyanate-based heat curing agents are 2,4-trilene diisocyanate, 2,6-triylene diisocyanate, hydrogenated triylene diisocyanate, 1,3-xylene diisocyanate, 1,4-xylene diisocyanate, di Phenylmetal-4,4-diisocyanate, 1,3-bisisocyanatomethyl cyclohexane, tetramethylxylene diisocyanate, 1,5-naphthalene diisocyanate, 2,2,4-trimethyl hexamethylene diisocyanate, 2,4 At least one selected from the group consisting of, 4-trimethyl hexamethylene diisocyanate, triylene diisocyanate adduct of trimethylolpropane, xylene diosocyanate adduct of trimethylolpropane, toriphenylmethane toisocyanate and methylene bistri isocyanate It may include.

The pressure-sensitive adhesive composition may further include a silane compound. The silane compound may be included in an amount of 0.5 to 3 parts by weight, preferably 1 to 2 parts by weight, based on 100 parts by weight of the acrylic copolymer. Within this range, the reaction time requirement with the hydroxyl group is short, and the reaction polymerization control is easy. It is also located in the side chain of the hydroxyl group can be more excellent adhesion.

In the present invention, 'silane' or 'silane group' may refer to a silane (SiH ₄ ) or a silane substituted with 1 to 4 substituents, for example, halogen or linear or branched alkoxy of C 1 -C 6.

In the present invention, 'silane compound' or 'monomer containing silane group' may mean a compound capable of binding to the hydroxyl group including the 'silane' or 'silane group', or may mean a conventional silane coupling agent. Preferably, the monomer containing the silane group may be bonded to the hydroxyl group through an isocyanate moiety.

The monomer comprising a silane compound or silane group may include vinyl trichloro silane, vinyl trimethoxy silane, vinyl triethoxy silane, 3-isocyanate propyl trimethoxy silane or 3-isocyanate propyl triethoxy silane, but these It is not limited to. For example, the silane compound or monomer comprising a silane group may include an isocyanate moiety, for example 3-isocyanate propyl trimethoxy silane.

The silane compound may mean a conventional silane coupling agent, and includes, for example, polymerizable fluorinated group-containing silicon compounds such as vinyl trimethoxy silane, vinyl triethoxy silane, and (meth) acryloxy propyl trimethoxysilane; Silicon compounds having an epoxy structure, such as 3-glycidoxy propyl trimethoxysilane, 3-glycidoxy propylmethyl dimethoxysilane, and 2- (3,4-epoxycyclohexyl) ethyl trimethoxysilane; Amino group-containing silicon compounds such as 3-aminopropyl trimethoxysilane, N- (2-aminoethyl) -3-aminopropyl trimethoxysilane, N- (2-aminoethyl) -3-aminopropyl methyl dimethoxysilane ; And 3-chloro propyl trimethoxysilane and the like may include one or more selected from the group consisting of, but is not limited thereto.

The pressure-sensitive adhesive composition of the present invention can be prepared by the following steps:

(Meth) acrylic acid alkyl esters; (Meth) acrylic acid esters having a hydroxyl group; And copolymerizing a monomer having a pyrrolidoneyl group to prepare an acrylic copolymer (first step); And

Adding a curing agent to the acrylic copolymer (second step).

First step

The first step is to prepare an acrylic copolymer binder, (meth) acrylic acid alkyl ester; (Meth) acrylic acid ester containing a hydroxyl group; And an initiator is added to the monomer having a pyrrolidoneyl group and polymerized to prepare an acrylic copolymer.

Initiators include 2,2-azobis (2,4-dimethylvalenonitrile), azobisisobutyronitrile, benzoyl peroxide, dilauroyl peroxide, tertiary-butyl- (2-ethylhexyl) mono Peroxycarbonate, tertiary-amyl- (2-ethylhexyl) monoperoxycarbonate, 1,1-di (tertiary-butylperoxy) cyclohexane, 1,1-di (tertiary-amylperoxy) cyclo Hexane, tert-butyl peroxy-3,5,5-trimethylhexanoate, 1,1-di (tert-butyl peroxy) -3,3,5-trimethylcyclohexane, potassium persulfate, sodium per It may be one kind or two or more kinds selected from the group consisting of sulfate, ammonium persulfate and azo water-soluble initiator, but is not limited thereto. Preferably, azobisisobutyronitrile can be used.

The initiator may be included in an amount of 0.01-1 part by weight based on 100 parts by weight of the (meth) acrylic acid alkyl ester.

In the first step, (meth) acrylic acid alkyl ester; (Meth) acrylic acid esters having a hydroxyl group; And a solvent capable of dissolving N-vinylpyrrolidone. As the solvent, conventional ones known to those skilled in the art can be used. For example, ethyl acetate and the like can be used.

The first step may further include a monomer including a silane group to prepare an acrylic copolymer.

In the first step, the polymerization temperature and the polymerization time can be appropriately controlled. For example, the polymerization may be carried out at a polymerization temperature of 65 to 70 ° C. for 6 to 8 hours.

.

Step 2

The second step is to prepare a final acrylic pressure-sensitive adhesive composition by adding a curing agent to the acrylic copolymer. Preparation of the pressure-sensitive adhesive composition can be carried out by conventional methods. For example, it may be prepared by adding an acrylic polymer and a curing agent to a solvent such as methyl ethyl ketone and stirring at room temperature for 30 to 60 minutes.

In the second step, a silane compound may be further added.

The present invention provides a polarizing film comprising the pressure-sensitive adhesive composition. The polarizing film may be produced by a conventionally known method using an adhesive composition. The polarizing film may include 3 inches or 19 inches, but is not limited thereto.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

Details that are not described herein will be omitted since those skilled in the art can sufficiently infer technically.

Example

Preparation Example 1 Preparation of Acrylic Copolymer

60 g of ethyl acetate, 55 g of butyl acrylate, 20 g of methyl acrylate, 5 g of 2-hydroxyethyl methacrylate, and 20 g of N-vinylpyrrolidone were added to a 1 L four-neck flask, and the temperature was maintained at 70 ° C. 0.08 g of azobisisobutyronitrile as an initiator was dissolved in 20 g of ethyl acetate. After reacting at 65 ° C. for 3 hours, 320 g of ethyl acetate was added and cooled to 40 ° C. to prepare an acrylic copolymer. The entire reaction process was carried out with a 10 cc / min nitrogen. The prepared acrylic copolymer had a viscosity of 4,500 cps and a solid content of 25%. The weight average molecular weight was 900,000 g / mol and the polydispersity was 3.4. The viscosity was measured by Spindle No. # 7 at 25 ° C. with a Brookfield viscometer DV-II +. Polydispersity is the weight average molecular weight divided by the number average molecular weight, 0.01-0.015g of acrylic copolymer was dissolved in 10ml THF, and the obtained dissolved sample was filtered using a 0.45㎛ syringe filter and waters 2414 RI with a measuring instrument. It was measured using a detector. As a standard sample, 10 kinds of SM-105 of Polysturene Shodex were used.

Preparation Example 2 Preparation of Acrylic Copolymer

60 g of ethyl acetate, 55 g of butyl acrylate, 20 g of methyl acrylate, 5 g of 2-hydroxyethyl methacrylate, and 20 g of N-vinylpyrrolidone were added to a 1 L four-neck flask, and the temperature was maintained at 70 ° C. 0.08 g of azobisisobutyronitrile as an initiator was dissolved in 20 g of ethyl acetate. After maintaining for 3 hours, 320 g of ethyl acetate was added and cooled to 40 ° C. After cooling, 2 g of 3-isocyanate propyl triethoxysilane and 0.01 g of catalyst DBTDL (dibutyltin dilaurate) were added and reacted for 12 hours. The entire reaction process was carried out with a 10 cc / min nitrogen. The prepared acrylic copolymer had a viscosity of 4,800 cps and a solid content of 25%. The weight average molecular weight was 930,000 g / mol and the polydispersity was 3.2.

Preparation Example 3-6: Preparation of Acrylic Copolymer

An acrylic copolymer was prepared in the same manner as in Example 1, except that the content of each component was changed as in Table 1 below.

Manufacturing example One 2 3 4 5 6 Butyl acrylate 55 53 38 38 65 45 Methyl acrylate 20 20 40 15 20 5 2-hydroxyethyl
Methacrylate 5 5 5 5 5 5 N-vinylpyrrolidone 20 20 15 40 10 45 3-isocyanate
Propyl Triethoxysilane - 2 2 2 - -

Example 1-4 and Comparative Example 1-2

The pressure-sensitive adhesive composition was prepared by adding the acrylic copolymer, the curing agent, and / or the silane compound prepared above to 10 parts by weight of methyl ethtone ketone in the amounts shown in Table 2 below and stirring at 25 ° C. for 30 minutes. The unit of Table 2 is a weight part (solid content basis).

Example Comparative example One 2 3 4 One 2 Acrylic Copolymer Preparation Example 1 100 - - - - - Production Example 2 - 100 - - - - Production Example 3 - - 100 - - - Production Example 4 - - - 100 - - Production Example 5 - - - - 100 - Production Example 6 - - - - - 100 Hardener 0.5 0.5 0.5 0.5 0.5 0.5 Silane coupling agent 2 - 2 - - -

* Curing agent: trimethylolpropane modified toluene diisocyanate (AK-75, Aekyung Chemical)

* Silane coupling agent: 3-glyoxypropylmethoxy silane (KBM-403, Shin-Yetsu Chemical Co., Ltd.)

The evaluation items shown in Table 3 were evaluated for the pressure-sensitive adhesive composition prepared above.

* Assessment Methods:

1. Observation of coating liquid appearance

The pressure-sensitive adhesive compositions prepared in Examples and Comparative Examples were left at room temperature for 1 day and then observed for transparency / opacity.

2. Peel strength (gf / 25mm)

The 180 degree peeling force between the adhesive composition and the glass substrate was measured by the method defined in JIS 2107. The pressure-sensitive adhesive composition sample was cut into 25 mm x 100 mm and laminated to the glass surface. Each of the adhesive layer and the glass substrate were connected to the upper and lower jig in a 30kgf load cell by using a tensile tester, and then peeled at a speed of 300 mm / min. Measured.

3. Cutability / rework

The polarizing plate (400 mm × 250 mm) coated with the pressure-sensitive adhesive composition prepared in Examples and Comparative Examples was cut with a Thomson cutter and the cut section of the pressure-sensitive adhesive layer was observed. The specimen was prepared by attaching to both sides of the glass substrate and applying a pressure of 4-5 kg / cm ² . The specimen was left at 70 ° C. for 6 hours, and then cooled slowly at room temperature for 1 hour or longer to check whether the adhesive remained on the glass substrate. Evaluation criteria are as follows.

(Circle): The adhesive residue of cutting surface and the degree to which adhesive fell out are good (no residue at the time of rework)

(Triangle | delta): The adhesive residue of a cutting surface and the extent to which an adhesive fell out are some (there is some residue at the time of rework)

X: The adhesive residue of the cutting surface and the grade which the adhesive came out (there is residue at the time of rework)

4. Light leak

The uniformity of light transmittance was investigated using the same specimen as in the following durability evaluation. The backlight was used to check for light leaks from the dark room. A coated polarizing plate (400 mm x 200 mm) was attached to the glass substrate (400 mm x 200 mm x 15 mm) on both sides across the optical axis. Specimens used for evaluation of light transmittance uniformity were used after being left for 250 hours at a temperature of 80 ° C., or 250 hours at a temperature of 60 ° C. and a humidity of 90% and a humidity of 90 ° C. It was. Evaluation criteria are as follows.

(Circle): It is hard to judge visually nonuniformity of light transmittance

(Triangle | delta): There exists a some nonuniform phenomenon of light transmittance.

X: There exists a light nonuniformity phenomenon.

5. Adhesive creep (mm)

The polarizing plate to which the pressure-sensitive adhesive composition prepared in Examples and Comparative Examples was applied was attached to a glass plate with an adhesive area of 1.5 cm x 1.5 cm, and then left at 22 ° C. and 50% RH for 3 days to prepare a specimen. The adhesive creep was measured as the distance (mm) exerted when a 2 kgf force was applied to the specimen for 10 minutes using a universal test machine (UTM).

6. Durability and reliability

Polarizing plates (100 mm x 175 mm) coated with a pressure-sensitive adhesive composition prepared in Examples and Comparative Examples were attached to both surfaces of a glass substrate and a specimen was prepared by applying a pressure of 4-5 kg / cm ² . At this time, clean room work was performed to prevent bubbles or foreign substances. Heat resistance characteristics of the prepared specimens were evaluated by observing the occurrence of bubbles or peeling after leaving for 500 hours at a temperature of 80 ℃. Heat and humidity resistance was evaluated by observing the occurrence of bubbles or peeling after leaving for 500 hours at a temperature of 60 ℃ and a relative humidity of 90%. Immediately before evaluation, the sample was left at room temperature for 1 hour and then evaluated by visual observation or by microscope. Evaluation criteria are as follows.

○: no bubbles or peeling

(Triangle | delta): There exist some bubbles and peeling.

X: There is bubble or peeling.

Example Comparative example Evaluation item One 2 3 4 One 2 Coating liquid appearance
observe Transparency Transparency Transparency Transparency Transparency Transparency Peel Strength (gf / 25mm) 550 600 500 400 1000 100 Cutting / reworkability ○ ○ ○ ○ △ ○ Light fountain 3 inches Good Good Good Good Bad Good 19 inches Good Good Good Good Good Good adhesive
Creep (mm) 0.203 0.211 0.247 0.199 0.502 0.132 Endurance
responsibility Heat resistant ○ ○ ○ ○ △ △ Heat resistance ○ ○ ○ ○ △ ×

As shown in Table 3, it can be seen that the pressure-sensitive adhesive composition according to the present invention has excellent durability, excellent effect of suppressing light leakage, and showed remarkable adhesiveness and peel strength (see Example 1-4). It can be seen that the pressure-sensitive adhesive composition containing 15-40 parts by weight of N-vinylpyrrolidone in 100 parts by weight of the acrylic copolymer has an excellent effect of suppressing light leakage and an effect of improving heat resistance (Examples 1 and 3-4, Comparative Example). 1-2).

Claims (17)

Acrylic copolymer containing the monomer which has a pyrrolidoneyl group; And
Contains a curing agent,
The monomer having a pyrrolidoneyl group is 11 to 40 parts by weight of the acrylic copolymer 100 parts by weight of the pressure-sensitive adhesive composition.
The pressure-sensitive adhesive composition of claim 1, wherein the acrylic copolymer is a polymer obtained by polymerizing a monomer having a (meth) acrylic acid alkyl ester having an alkyl group, a (meth) acrylic acid ester having a hydroxyl group and a pyrrolidoneyl group.
The acrylic copolymer of claim 2, wherein the acrylic copolymer has 60-83 parts by weight of the (meth) acrylic acid alkyl ester, 1-10 parts by weight of the (meth) acrylic acid ester having the hydroxyl group, and the pyrrolidoneyl group in 100 parts by weight. An adhesive composition comprising 11 to 40 parts by weight of a monomer having.
The pressure-sensitive adhesive composition of claim 2, wherein the acrylic copolymer further has a silane group.
The method of claim 4, wherein the acrylic copolymer is a (meth) acrylic acid alkyl ester having an alkyl group, a (meth) acrylic acid ester having a hydroxyl group, a monomer having a pyrrolidoneyl group and a monomer having a silane group polymerized therein. Pressure-sensitive adhesive composition.
The pressure-sensitive adhesive composition of claim 4, wherein the monomer having a silane group is introduced into the main chain of the acrylic copolymer by an isocyanate moiety.
The method of claim 2, wherein the acrylic copolymer is a monomer of Formula 1: a monomer of Formula 2: the monomer having a pyrrolidoneyl group is contained in a molar ratio of 63-84: 3-8.5: 14-29 Pressure-sensitive adhesive composition.
<Formula 1>
CH2 = CR-C (= O) O- (CH2) p-CH3
Wherein R is -H or-(CH2) n-CH3, n is an integer from 0-5,
p is an integer from 0-10)
<Formula 2>
CH2 = CR-C (= O) O- (CH2) q-OH
Wherein R is -H or-(CH2) n-CH3, n is an integer from 0-5,
q is an integer from 1-10)
The method of claim 5, wherein the acrylic copolymer is a monomer of formula 1: monomer of formula 2: monomer having a pyrrolidoneyl group: monomer of formula 3 59-85: 1-8.5: 14-30: 0.5 Pressure-sensitive adhesive composition, characterized in that it is included in a molar ratio of 1.5.
<Formula 1>
CH2 = CR-C (= O) O- (CH2) p-CH3
Wherein R is -H or-(CH2) n-CH3, n is an integer from 0-5,
p is an integer from 0-10)
<Formula 2>
CH2 = CR-C (= O) O- (CH2) q-OH
Wherein R is -H or-(CH2) n-CH3, n is an integer from 0-5,
q is an integer from 1-10)
<Formula 3>
(R2) (R3) (R4) Si- (CH2) s-R5
(Wherein R2, R3, and R4 are halogen or an alkoxy group having 1-5 carbon atoms, when s is 0, R5 is a vinyl group and when s is 1-10, R5 is NCO).
The method of claim 5, wherein the acrylic copolymer is a monomer of the general formula (I): a monomer of the general formula (II): a monomer having the pyrrolidoneyl group: a monomer of the formula 4 or 5 is 56-84: 1-8: 14- Pressure-sensitive adhesive composition, characterized in that included in the molar ratio of 31: 1-4.5.
<Formula 1>
CH2 = CR-C (= O) O- (CH2) p-CH3
Wherein R is -H or-(CH2) n-CH3, n is an integer from 0-5,
p is an integer from 0-10)
<Formula 2>
CH2 = CR-C (= O) O- (CH2) q-OH
Wherein R is -H or-(CH2) n-CH3, n is an integer from 0-5,
q is an integer from 1-10)
&Lt; Formula 4 >
CH2 = CR-C (= O) O- (CH2) r-COOH
Wherein R is -H or-(CH2) n-CH3, n is an integer from 0-5,
r is an integer from 0 to 10)
&Lt; Formula 5 >
CH2 = CR-C (= O) OH
(Wherein R is —H or — (CH 2) n —CH 3 and n is an integer from 0 to 5).
According to claim 1, wherein the weight average molecular weight of the acrylic copolymer is an adhesive composition, characterized in that 800,000-1,500,000g / mol.
The pressure-sensitive adhesive composition of claim 1, wherein the polydispersity of the acrylic copolymer is 1-5.
The pressure-sensitive adhesive composition of claim 1, wherein the pressure-sensitive adhesive composition comprises 94-99.8 parts by weight of the acrylic copolymer and 0.2-6 parts by weight of a curing agent.
The pressure-sensitive adhesive composition of claim 1, wherein the curing agent is a heat curing agent.
The pressure-sensitive adhesive composition of claim 13, wherein the curing agent comprises at least one selected from the group consisting of isocyanate, epoxy, aziridine, melamine, amine, imide, carbodiimide, and amide.
The pressure-sensitive adhesive composition of claim 1, wherein the pressure-sensitive adhesive composition further comprises a silane compound.
The pressure-sensitive adhesive composition of claim 15, wherein the silane compound is included in an amount of 0.5 to 3 parts by weight based on 100 parts by weight of the acrylic copolymer.
The polarizing film containing the composition of any one of Claims 1-16.