KR101047922B1 - Acrylic pressure-sensitive adhesive composition for polarizing plate - Google Patents

Abstract

The present invention relates to an acrylic pressure-sensitive adhesive composition, more specifically, an acrylic copolymer (A); UV curable crosslinking agent (B); Polyfunctional crosslinking agent (C); Photoinitiator (D); And an acrylic monomer (E) to reduce the aging process by a few seconds to several minutes by using a combination of a thermosetting method and an ultraviolet irradiation method, and to prevent a decrease in stress relaxation performance of the pressure-sensitive adhesive by increasing the crosslinking point by UV curing. The present invention relates to an acrylic pressure-sensitive adhesive composition capable of maintaining UV light performance by advancing UV curing in the state of adding a (meth) acrylic acid ester monomer (E).

Polarizing plate, acrylic pressure sensitive adhesive, cutting, acrylic copolymer, (meth) acrylic acid ester monomer, UV curing, light leakage

Description

Acrylic pressure-sensitive adhesive composition for polarizing plate {Acrylic Pressure-Sensitive Adhesive Composition for the Polarizing Film}

The present invention relates to an acrylic pressure-sensitive adhesive composition for polarizing plates, and more particularly, to an acrylic copolymer (A), a UV curable crosslinking agent (B), a polyfunctional crosslinking agent (C), a photoinitiator (D), and a (meth) acrylic acid ester monomer (E). Including a), the present invention relates to a pressure-sensitive adhesive composition for a polarizing plate that can significantly reduce the aging time during the manufacturing process of the polarizing plate and a polarizing plate produced therefrom.

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; It is common to include a multilayered polarizing plate, a retardation plate, and an additional functional film layer, etc., which are incorporated into 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. to be.

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 thermal or wet heat conditions, dimensional stability due to shrinkage or expansion of materials with unidirectional molecular arrangements is lacking. Therefore, in order to relieve the stress caused by shrinkage and expansion of the polarizing plate, an adhesive must be used.

Most commonly used as the pressure-sensitive adhesive in the above is a solvent-type pressure-sensitive adhesive using an acrylic polymer resin. However, the acrylic pressure-sensitive adhesive may reduce the stress caused by the polarizing plate due to the low Tg, but the cohesive strength of the acrylic adhesive is low, and the crosslinking is possible due to the lack of durability due to shrinkage and expansion of the polarizing plate in a high temperature and high humidity environment. It contains a monomer which has a functional group, crosslinks it with an isocyanate, an epoxy, and an aziridine system crosslinking agent, and increases cohesion force of an adhesive and uses it. Such isocyanate-based or epoxy-based crosslinking agents do not complete crosslinking immediately after drying, and require an aging time of about 1 day to 1 week. If the cutting and cutting process is performed without aging, If the adhesive adheres to the blade, or the adhesive adheres to other polarizers, foreign substances are generated. In addition, an unexpected dimensional change of the polarizing plate or the retardation plate according to the storage temperature and time during the aging period is a factor that worsens the optical properties of the polarizing plate.

Therefore, regardless of the curing rate of the thermosetting pressure-sensitive adhesive, after the rapid curing proceeds the plywood polarizing plate and the pressure-sensitive adhesive, there is an urgent need for an adhesive that does not require additional aging equipment and aging period.

In order to realize an adhesive that does not require an aging process, Japanese Patent Application Laid-open No. Hei 9-95775 proposes a non-solvent type adhesive using UV, and Japanese Patent Laid-open No. Hei 9-137135 proposes an alkyl (meth) acrylate and vinyl having a polar group A photopolymerizable pressure-sensitive adhesive composition using a monomer, a polyfunctional vinyl monomer, and a photopolymerization initiator has been proposed.

However, the UV-type pressure-sensitive adhesive composition used in the above document has a short curing time, but it is difficult to apply a thin thickness of the pressure-sensitive adhesive layer, to realize the accuracy of the thickness due to shrinkage of the polymer by UV polymerization and curing The disadvantage is that it is difficult. In addition, in order to minimize the inhibition of polymerization by oxygen of the photoinitiator, there is a disadvantage to make an inert gas atmosphere such as nitrogen, there is a problem that the remaining monomer (monomer) is likely to remain when sufficient UV irradiation is not made, or the thickness of the adhesive Have

In order to solve the conventional problems as described above, by reducing the aging process to a few seconds to a few minutes by using a combination of the heat curing method and ultraviolet irradiation method, the cross-linking point is increased by UV curing can reduce the stress relaxation performance of the pressure-sensitive adhesive In order to prevent this, UV curing was carried out in the state in which an acrylic monomer was added, and it was found that light leakage performance by stress relaxation of the pressure-sensitive adhesive could be maintained and the present invention was completed.

Accordingly, an object of the present invention is to provide an acrylic pressure-sensitive adhesive composition for a polarizing plate which can be directly transferred to a polarizing plate cutting and cutting process without undergoing additional equipment and aging period after the polarizing plate and the adhesive are laminated with a thermosetting adhesive.

Another object of the present invention is to provide an adhesive sheet containing an acrylic pressure-sensitive adhesive composition having the above characteristics and a method of manufacturing the same.

Still another object of the present invention is to provide a polarizing plate including a pressure-sensitive adhesive layer containing an acrylic pressure-sensitive adhesive composition having the above characteristics and a manufacturing method thereof.

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

In order to achieve the above object, the present invention

Acrylic copolymer (A); Based on 100 parts by weight of the acrylic copolymer solid content,

UV curable crosslinking agent (B) 5 to 50 parts by weight;

0.01 to 10 parts by weight of the multifunctional crosslinking agent (C);

Photoinitiator (D) 0.1 to 50 parts by weight; And

It relates to an acrylic pressure-sensitive adhesive composition containing 5 to 200 parts by weight of (meth) acrylic acid ester monomer (E).

In the acrylic pressure-sensitive adhesive composition according to the present invention, each component is specified by the following.

Acrylic Copolymer (A)

The acrylic copolymer (A) used in the present invention

Iii) 90 to 99.9 parts by weight of a (meth) acrylic acid ester monomer having an alkyl group having 1 to 12 carbon atoms; And

Ii) It is preferred to include 0.1 to 10 parts by weight of a vinyl monomer and / or an acrylic monomer having a crosslinkable functional group.

The (meth) acrylic acid ester monomer having an alkyl group having 1 to 12 carbon atoms of (i) is methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate , n-butyl (meth) acrylate, t-butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, 2-ethylhexyl ( Meta) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, benzyl acrylate, etc. can be used individually or in mixture of 2 or more types.

The (meth) acrylic acid ester monomer having an alkyl group having 1 to 12 carbon atoms is preferably contained in an amount of 90 to 99.9 parts by weight. When the content is less than 90 parts by weight, the initial adhesive strength is lowered. Problems with durability may occur.

The vinyl monomer and / or the acrylic monomer having the crosslinkable functional group of ii) reacts with the crosslinking agent to impart cohesive force or adhesive strength by chemical bonding so that cohesive breakage of the pressure-sensitive adhesive does not occur under high temperature or high humidity conditions.

The vinyl monomer having a crosslinkable functional group and / or the acrylic monomer may be 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6- Monomers containing a hydroxy group such as hydroxyhexyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, or 2-hydroxypropylene glycol (meth) acrylate; Monomers containing carboxyl groups such as acrylic acid, methacrylic acid, acrylic acid duplexes, itaconic acid, maleic acid, maleic anhydride, or fumaric acid; Or monomers containing nitrogen such as acrylamide, N-vinyl pyrrolidone, or N-vinyl caprolactam, or the like, may be used alone or in combination of two or more thereof.

The vinyl monomer having a crosslinkable functional group and / or the acrylic monomer is preferably included in an acrylic copolymer in an amount of 0.1 to 10 parts by weight, and when the content is less than 0.1 parts by weight, aggregation breakdown is likely to occur at high temperature or high humidity. If there is a problem, if it exceeds 10 parts by weight, compatibility is reduced, causing surface migration to occur badly, flow characteristics are reduced, and there is a problem that stress relaxation is lowered due to an increase in cohesive force.

In addition, the acrylic copolymer (A) according to the present invention preferably has a weight average molecular weight of 80 to 3 million. If the weight average molecular weight is less than 800,000, the durability of the pressure-sensitive adhesive may be inhibited, and if the weight-average molecular weight exceeds 300 million, the coating property is significantly lowered due to the high viscosity.

The acrylic copolymer can be produced by conventional methods such as solution polymerization, photopolymerization, bulk polymerization, suspension polymerization, and emulsion polymerization.

UV  Curable Crosslinking agent (B)

The UV-curable crosslinking agent (B) used in the present invention is used by mixing so as to be in the range of 5 to 50 parts by weight based on 100 parts by weight of the solid content of the acrylic copolymer (A), and according to the amount of the adhesive properties and aging of the pressure-sensitive adhesive (aging) ) You can adjust the time reduction. If the content of the UV-curable crosslinking agent (B) is less than 5 parts by weight, the desired aging time may not be shortened. If the content is 50 parts by weight or more, the cross-linking content may be increased to play a role of stress relaxation of the pressure-sensitive adhesive by shrinkage and expansion of the polarizing plate. It becomes impossible.

 UV-curable crosslinking agents include polyfunctional acrylates such as 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, 1,2-ethylene glycol diacrylate, or It is possible to use crosslinkable monomers, such as 1,12- dodecanediol acrylate.

Multifunctional Crosslinking agent (C)

The multifunctional crosslinking agent (C) used in the present invention serves to increase the cohesive force of the pressure-sensitive adhesive by reacting with the carboxyl group and the hydroxyl group of the acrylic copolymer (A).

The content of the multifunctional crosslinking agent (C) is preferably used in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the solid content of the acrylic copolymer (A).

As the multifunctional crosslinking agent (C), an isocyanate-based, epoxy-based, aziridine-based, metal chelate-based crosslinking agent, or the like may be used.

Examples of the isocyanate-based crosslinking agent include polyols such as tolylene diisocyanate, xylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isoform diisocyanate, tetramethyl xylene diisocyanate, naphthalene diisocyanate, and trimethylolpropane. And reactants.

Examples of the epoxy-based crosslinking agents include ethylene glycol diglycidyl ether, triglycidyl ether, trimethol propane triglycidyl ether, N, N, N'N 'tetraglycidyl ethylenediamine, glycerin diglycidyl ether, and the like. Can be mentioned.

Examples of the aziridine-based crosslinking agent include N, N'toluene-2,4-bis (1-aziridinecarboxide) and N, N'diphenylmethane-4,4`-bis (1-aziridinecarboxide). , Triethylenemelamine, bisisoprotaloyl-1- (2-methylaziridine), tri-1-aziridinylphosphine oxide and the like.

Examples of the metal chelate crosslinking agent include compounds in which polyvalent metals such as aluminum, iron, zinc, tin, titanium, antimony, magnesium, and vanadium are coordinated with acetylacetone or ethyl acetoacetate.

Photoinitiator (D)

The photoinitiator (D) used in the present invention is a material for initiating the reaction of the UV-curable crosslinking agent by UV irradiation, taking into consideration the curing rate and yellowing characteristics of the resin composition, and selecting and using the type and content appropriately. In some cases, two or more kinds of photocuring initiators may be mixed and used.

It is preferable to use 0.1-50 weight part of said photoinitiator (D) with respect to 100 weight part of solid content of a high molecular weight (meth) acrylic-type copolymer (A). When the content of the composition is less than 0.1 parts by weight, the curing rate is slow, and when the content is 50 parts by weight or more, storage of the composition is deteriorated.

Examples of photoinitiators (D) that can be used in the present invention include hydroxycyclohexylphenylketone (Irgacure # 184), 2-methyl-1 [4- (methylthio) phenyl] -2-morpholino-propane- 1-one (2-methyl-1 [4- (methythio) phenyl] -2-morpholino-propan-1-on; Irgacure # 907), α, α-methoxy-α-hydroxyacetophenone (α, α -methoxy-α-hydroxyacetophenone (Irgacure # 651), and 2-hydroxy-2-methyl-1-phenyl-propan-1-one (2-hydroxy-2-methyl-1-phenyl-propan-1-one; Irgacure # 1173).

( Meta Acrylic Acid Ester Monomer (E)

The (meth) acrylic acid ester monomer (E) used in the present invention is not particularly limited, and those conventionally used in pressure-sensitive adhesives may be used, and such acrylic monomers include (meth) acrylic acid having an alkyl group having 1 to 12 carbon atoms. It is an ester monomer and can mix with the polar monomer copolymerizable with this monomer. More specifically, butyl (meth) acrylate, hexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) Acrylates and the like.

In the case of the (meth) acrylic acid ester monomer (E), if the composition is different from that of the acrylic copolymer (A), macro-separation may occur. It is desirable to have a monomer type and content. When the acryl-based copolymer (A) and the (meth) acrylic acid ester monomer (E) are subjected to macrophase separation, the turbidity of the pressure-sensitive adhesive increases, thereby deteriorating optical properties, and deteriorating the adhesive properties such as durability and adhesion. Will bring.

Solid content ratio of the (meth) acrylic acid ester monomer (E) used by this invention is 5-200 weight part with respect to a high molecular weight (meth) acrylic-type copolymer (A), More preferably, it is 50-150 weight part. When the content of the acrylic monomer is 200 parts by weight or more, the coating viscosity is lowered during coating, the coating property is worse, and residual monomer may be present after UV curing.

Although the (meth) acrylic acid ester monomer (E) is not cured but UV curing progresses, it is preferable to add the (meth) acrylic acid ester monomer (E) to activate the reaction of the UV curable crosslinking agent (B). Mc (Molecular weight between crosslink point) can be large enough to prevent degradation of light leakage by UV curing.

Moreover, the silane coupling agent for improving adhesive durability can be added with other additives. The silane coupling agent increases the durability by increasing the adhesive force with time and heat to prevent bubbles or peeling at high temperature and high humidity.

The silane coupling agent is preferably included in an amount of 0.01 to 10 parts by weight with respect to 100 parts by weight of the acrylic copolymer (A). When the content is less than 0.01 parts by weight, the increase in adhesion due to time and heat is insignificant, and the amount is greater than 10 parts by weight. If it is, there is a problem that the durability is lowered due to excessive bubbles or peeling occurs due to the excessive use.

The silane coupling agent is β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxy propyltrimethoxysilane, γ-glycidoxy propylmethyldiethoxysilane, or γ-glycidoxy propyl Triethoxysilane and the like can be used.

In addition, 1 to 100 parts by weight of the tackifying resin used to adjust the adhesive performance can be added. When the excess amount of the component is used, the cohesive force of the pressure-sensitive adhesive may be reduced, so it is preferably included in an appropriate amount.

The tackifying resin is (hydrogenated) hydrocarbon resin, (hydrogenated) rosin resin, (hydrogenated) rosin ester resin, (hydrogenated) terpene resin, (hydrogenated) terpene phenol resin, polymerized rosin resin, or polymerized rosin ester resin Etc. can be used.

In addition, acrylic low molecular weights, epoxy resins, and curing agents may be additionally mixed for specific purposes, and UV stabilizers, antioxidants, colorants, reinforcing agents, fillers, antifoaming agents, surfactants, or plasticizers may be appropriately added according to general purposes. Can be used.

The present invention also relates to an adhesive sheet and a method of manufacturing the same.

The adhesive sheet

materials; And

It is formed on one side or both sides of the base material, and includes an adhesive layer containing the acrylic pressure-sensitive adhesive composition according to the present invention.

2-100 micrometers or less are preferable, and, as for the thickness laminated | stacked of an adhesive, More preferably, it is 5-50 micrometers or less.

The manufacturing method of the adhesive sheet

a) applying the pressure-sensitive adhesive composition according to the invention on the surface of the peelable substrate and then drying;

b) transferring the pressure-sensitive adhesive layer formed on the surface of the peelable substrate to the surface of the substrate film; And

c) irradiating UV on the substrate surface.

In the manufacturing method of the pressure-sensitive adhesive sheet, a separate N ₂ (nitrogen) purging is not necessary, and the pressure-sensitive adhesive layer can be formed by single-sided or double-sided irradiation according to the UV transmission characteristics of the polarizing plate.

The invention also polarizing film or polarizing element; And

Pressure-sensitive adhesive layer containing the acrylic pressure-sensitive adhesive composition according to the invention

It relates to a polarizing plate and a method for producing the same.

The polarizing film or the polarizing element constituting the polarizing plate is not particularly limited.

2-100 micrometers or less are preferable, and, as for the thickness of an adhesion layer, 5-50 micrometers is more preferable inside. 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 manufacturing method of the polarizing plate containing the adhesive layer containing the adhesive composition which concerns on this invention,

Applying the acrylic pressure-sensitive adhesive composition according to the present invention to a peelable base material and then drying to form an adhesive layer;

Plywood the adhesive layer on a polarizing plate (2); And

And (3) irradiating UV to one or both sides of the polarizer plated with the adhesive.

In the polarizing plate to which the pressure-sensitive adhesive of the present invention is applied, the UV-curable crosslinking agent (B) and the (meth) acrylic acid ester monomer (E) have a polymerization and crosslinking structure by the photoinitiator (D) to compensate for the slow crosslinking speed of the multifunctional crosslinking agent. In addition, as in the case of the conventional UV type crosslinking type, there is no need for an N ₂ (nitrogen) atmosphere to prevent crosslinking and inhibition of polymerization rate by oxygen, and there is no need to apply an adhesive between both sides of the film. Only the need for existing equipment can be fully utilized.

UV irradiation conditions may vary depending on the respective polarizing plate and pressure-sensitive adhesive manufacturing method, it is about 5 ~ 1000mJ / ㎠ and the irradiation time is 5 ~ 300sec. In the case of UV irradiation, a mercury lamp, a metal halide lamp, or the like may be used.The irradiation temperature is maintained at 130 ° C. or lower in consideration of thermal expansion and contraction of the polarizing plate and the peelable substrate. It is preferable.

The present invention also relates to a liquid crystal display device using a polarizing plate comprising a pressure-sensitive adhesive layer containing the acrylic pressure-sensitive adhesive composition according to the present invention.

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 a polarizing plate including the adhesive layer is bonded to one or both surfaces of a liquid crystal cell.

Hereinafter, preferred examples and comparative examples of the present invention are described. The following examples and comparative examples are described for the purpose of more clearly expressing the contents of the present invention, but the contents of the present invention are not limited to the following examples.

[Example]

<Acrylic adhesive production>

Example 1

1) Manufacture of Acrylic Copolymer (A)

Consists of 98 parts by weight of n-butyl acrylate (BA) and 2 parts by weight of 2-hydroxyethyl (meth) acrylate (2-HEMA) in a 1000 cc reactor equipped with a refrigeration system for easy reflux of nitrogen gas. The monomer mixture was added, and 100 parts by weight of ethyl acetate (EAc) was added as a solvent. Then, after purging nitrogen gas for 20 minutes to remove oxygen, it was maintained at 60 ℃. After homogeneous, 0.03 parts by weight of azobisisobutyronitrile (AIBN) diluted with 50% concentration in ethyl acetate was added as a reaction initiator. The reaction was carried out for 8 hours to prepare an acrylic copolymer (PA-1) having a molecular weight (measured using a polystyrene standard sample) of 1500 K.

2) Manufacture of acrylic adhesive

1.5 parts by weight of tolylene diisocyanate adduct (TDI-1) of trimethylolpropane with a polyfunctional isocyanate-based crosslinking agent (C) with respect to 100 parts by weight of the acrylic copolymer (PA-1) prepared above was respectively 15.5% by weight in ethyl acetate solution. After diluting with 50 ml of n-butyl acrylate (BA) monomer (E) relative to the solid content of the acrylic copolymer (PA-1), 1,6-hexanediol was added as a UV curable crosslinking agent (B). After mixing diacrylate (HDDA) 6.5 parts by weight relative to the solid content of the acrylic copolymer (PA-1), a, a-methoxy-a-hydroxyacetophenone (Irgacure # -651) was used as the photoinitiator (D). 2 parts by weight based on 100 parts by weight of the acrylic copolymer (PA-1) solid content was sufficiently stirred. In consideration of coating properties, the mixture was diluted to an appropriate concentration, uniformly mixed, coated on a release film having a thickness of 38 μm, and dried for 2 minutes in a 100 ° C. drying oven to prepare a uniform adhesive layer having a thickness of 25 μm.

Example 2

In Example 1, except that 150 parts by weight of the n-butyl acrylate monomer (E) was added in the same manner as in Example 1.

Example 3

In Example 1, except that 20 parts by weight of 1,6-hexanediol diacrylate (HDDA) as a UV curable crosslinking agent (B) was carried out in the same manner as in Example 1.

[Comparative Example]

Comparative Example 1

In Example 1, except that n-butyl acrylate monomer (E) was not added, 26 parts by weight of 1,6-hexanediol diacrylate (HDDA) was added as the UV-curable crosslinking agent (B). It carried out in the same way.

Comparative Example 2

1,6 which is Igacure # -651 (α, α-methoxy-α-hydroxyacetophenone) and a UV curable crosslinking agent (B) as the n-butyl acrylate monomer (E) and the photoinitiator (D) in Example 1 -Hexanediol diacrylate (HDDA) was not added, and was carried out in the same manner as in Example 1 except that no UV irradiation.

<Evaluation method>

1. Deformation force of polymer

After the prepared pressure-sensitive adhesive was transferred to a polyethylene terephthalate film having a thickness of 38 μm, the release film was peeled off, and then laminated to a polyethylene terephthalate film having a thickness of 38 μm, and the adhesive was laminated between the polyethylene terephthalate films. Thereafter, UV curing was performed using a metal halide UV lamp, and irradiation conditions were 30 mJ / cm 2. Leave the laminated adhesive at room temperature for 30 minutes to eliminate heat, cut it into a size of 2.5cm X 10cm, and bite the end of both sides (2cm) into the jig of Texture Analyzer (Stable Micro System), and then 1mm / The force of deformation of the polymer generated by pulling at the rate of sec was measured, and the trace of grass was visually confirmed. The specimens were measured after 30 minutes of UV irradiation and aged at room temperature for 7 days.

2. Polarizer Durability

The prepared pressure-sensitive adhesive was laminated on a polarizing plate, cut into 34 cm X 27 cm, and then laminated on a liquid crystal cell, and stored at 40 ° C. and 0.5 Mpa in an autoclave for 30 minutes. The temperature was 60 ° C. and the humidity was 90. It was left to stand for 150 hours in% atmosphere and evaluated by the following criteria.

(Circle): There is no peeling or lifting of an optical member.

X: There exists peeling and lifting of an optical member.

3. Polarizer light leakage performance

Light transmission uniformity (light leakage)

In order to investigate the uniformity of light transmission using the same specimen as above, it was observed whether light leaked out of the dark room using a 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. Light transmission uniformity 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.

Polymer strain of the sample 30 minutes after coating Force to deform polymer (gf) medium
(gf) Pool trail Primary Secondary 3rd Example 1 602 640 571 604 none Example 2 640 593 717 650 none Example 3 695 540 762 665 none Comparative Example 1 714 892 744 783 none Comparative Example 2 1362 1547 1325 1411 has exist

Polymer Deformation and Durability of Samples After Aging 7 Days After Coating Force on Polymer Deformation (gf) medium
(gf) durability Pool trail Light fountain
Primary Secondary 3rd Example 1 601 517 571 571 ○ none ○ Example 2 643 705 673 673 ○ none ⊙ Example 3 560 583 590 590 ○ none ○ Comparative Example 1 610 720 726 726 × none × Comparative Example 2 526 587 575 575 ○ none ○

In Table 1 and Table 2, in the case of Comparative Example 2, the polymer deformation force after 30 minutes after coating and after the aging period was about three times, and when two 38 μm polyethylene terephthalate films were peeled off. It could be seen visually that a fibrillation occurred. Except for Comparative Example 2, in Examples 1, 2, and 3 and Comparative Example 1, the polymer deformation force after 30 minutes after the coating and the aging period in all samples did not show a big difference, and almost no traces of glue appeared. Did. However, in Comparative Example 1, when only 1,6-hexanediol diacrylate (HDDA) was added as the UV-curable crosslinking agent (B), durability was poor due to excessive curing, and light leakage performance deteriorated by the stress relaxation of the pressure-sensitive adhesive was obvious.

The acrylic pressure-sensitive adhesive composition of the present invention can reduce the aging process to a few seconds to several minutes by using a combination of the thermosetting method and the ultraviolet irradiation method, and the cutting and cutting process is easy without the aging process after the adhesive is applied. In addition, the crosslinking point increases due to UV curing, which may lower the stress relaxation performance of the pressure-sensitive adhesive. In order to prevent this, UV curing is performed in the state in which (meth) acrylic acid ester monomer is added to maintain light leakage performance by stress relaxation of the pressure-sensitive adhesive. Can be.

Claims (19)

Acrylic copolymer (A); 5 to 50 parts by weight of a UV curable crosslinking agent (B), respectively, based on 100 parts by weight of the acrylic copolymer solid content; 0.01 to 10 parts by weight of the multifunctional crosslinking agent (C); Photoinitiator (D) 0.1 to 50 parts by weight; And (meth) acrylic acid ester monomer (E) 5 to 200 parts by weight. The method of claim 1, Acrylic copolymer (A) Iii) 90 to 99.9 parts by weight of a (meth) acrylic acid ester monomer having an alkyl group having 1 to 12 carbon atoms; And Ii) 0.1 to 10 parts by weight of a vinyl monomer and / or an acrylic monomer having a crosslinkable functional group Acrylic pressure-sensitive adhesive composition comprising a. The method of claim 2, (Meth) acrylic acid ester monomer i) having an alkyl group having 1 to 12 carbon atoms is methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n- Butyl (meth) acrylate, t-butyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2-ethylhexyl (meth) acryl with 2-ethylbutyl (meth) acryl Acrylic adhesive composition, characterized in that at least one selected from the group consisting of late, n-octyl (meth) acrylate, isooctyl (meth) acrylate, and isononyl (meth) acrylate. The method of claim 2, Vinyl monomers having a crosslinkable functional group and / or acrylic monomers ii) are 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6 -Hydroxyhexyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, 2-hydroxypropylene glycol (meth) acrylate, (meth) acrylic acid, acrylic acid duplex, itaconic acid, maleic acid, maleic anhydride , At least one selected from the group consisting of fumaric acid, acrylamide, N-vinyl pyrrolidone, and N-vinyl caprolactam. The method of claim 1, Acrylic copolymer (A) is an acrylic pressure-sensitive adhesive composition, characterized in that the weight average molecular weight of 80 to 3 million. The method of claim 1, UV curable crosslinking agent (B) is 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, 1,2-ethylene glycol diacrylate, and 1,12-dodecane Acrylic pressure-sensitive adhesive composition, characterized in that at least one member selected from the group consisting of diol acrylate. The method of claim 1, The polyfunctional crosslinking agent (C) is at least one selected from the group consisting of an isocyanate compound, an epoxy compound, an aziridine compound, and a metal chelate compound. The method of claim 1, Photoinitiator (D) is hydroxycyclohexylphenylketone (Irgacure # 184), 2-methyl-1 [4- (methylthio) phenyl] -2-morpholino-propane-1-on (2-methyl- 1 [4- (methythio) phenyl] -2-morpholino-propan-1-on; Irgacure # 907, α, α-methoxy-α-hydroxyacetophenone (α, α-methoxy-α-hydroxyacetophenone; Irgacure # 651) and 2-hydroxy-2-methyl-1-phenyl-propan-1-one (2-hydroxy-2-methyl-1-phenyl-propan-1-one; Irgacure # 1173) from the group consisting of Acrylic adhesive composition, characterized in that at least one selected. The method of claim 1, (Meth) acrylic acid ester monomer (E) is butyl (meth) acrylate, hexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acryl At least 1 type is chosen from the group which consists of a rate and isononyl (meth) acrylate, The acrylic adhesive composition characterized by the above-mentioned. The method of claim 9, The (meth) acrylic acid ester monomer and (meth) acrylic acid ester monomer (E) of an acryl-type copolymer (A) are the same kind, The acrylic adhesive composition characterized by the above-mentioned. The method of claim 1, The acrylic pressure sensitive adhesive composition further comprises 0.01 to 10 parts by weight of a silane coupling agent based on 100 parts by weight of the acrylic copolymer. The method of claim 1, Acrylic pressure-sensitive adhesive composition is an acrylic pressure-sensitive adhesive composition, characterized in that it further comprises 1 to 100 parts by weight of the tackifier resin with respect to 100 parts by weight of the acrylic copolymer. The method of claim 1, The acrylic pressure-sensitive adhesive composition further comprises at least one additive selected from the group consisting of an acrylic low molecular weight, an epoxy resin, a curing agent, an ultraviolet stabilizer, an antioxidant, a colorant, a reinforcing agent, a filler, an antifoaming agent, a surfactant, and a plasticizer. Acrylic pressure-sensitive adhesive composition. materials; And An adhesive layer containing the pressure-sensitive adhesive composition according to any one of claims 1 to 13 formed on one or both surfaces of the substrate. Adhesive sheet comprising a. a) applying a pressure-sensitive adhesive composition according to any one of claims 1 to 13 on the surface of the peelable substrate and then drying; b) transferring the pressure-sensitive adhesive layer formed on the surface of the peelable substrate to the surface of the substrate film; And c) irradiating UV on the substrate surface. Polarizing film or polarizing element; And An adhesive layer containing the acrylic pressure-sensitive adhesive composition according to any one of claims 1 to 13. Polarizing plate comprising a. The method of claim 16, And a polarizing plate further comprising at least one layer selected from the group consisting of a protective layer, a reflective layer, an antiglare layer, a retardation plate, a wide viewing angle compensation film, and a brightness enhancement film. (1) forming an adhesive layer by applying an acrylic pressure-sensitive adhesive composition according to any one of claims 1 to 13 on a peelable substrate and then drying it; Plywood the adhesive layer on a polarizing plate (2); And Method for producing a polarizing plate, characterized in that it comprises the step (3) of irradiating UV on one or both sides of the polarizing plate the pressure-sensitive adhesive is laminated. A liquid crystal display comprising a liquid crystal panel in which a polarizing plate according to claim 16 is bonded to one side or both sides of a liquid crystal cell.