KR101836366B1 - Acrylic copolymer and adhesive composition comprising the same - Google Patents

Abstract

(식 중, R₁은 수소 또는 메틸기이고, R₂는 탄소수 1 내지 10의 알렌킬기이며, X는 O 또는 NH임).The present invention relates to an acrylic copolymer and a pressure-sensitive adhesive composition containing the same, and more particularly, to a pressure-sensitive adhesive composition containing the acrylic copolymer and a pressure-sensitive adhesive composition containing the same, And high humidity), and a pressure-sensitive adhesive composition containing the acrylic copolymer.
[Chemical Formula 1]

(Wherein R ₁ is hydrogen or a methyl group, R ₂ is an alkylene group having 1 to 10 carbon atoms, and X is O or NH).

Description

TECHNICAL FIELD [0001] The present invention relates to an acrylic copolymer and a pressure-sensitive adhesive composition containing the same. BACKGROUND ART [0002]

The present invention relates to an acrylic copolymer excellent in corrosion resistance and adhesion durability of a metal and a pressure-sensitive adhesive composition containing the acrylic copolymer.

In general, a liquid crystal display device (LCD) includes a liquid crystal cell including a liquid crystal and a polarizing plate. In order to improve the display quality of the liquid crystal display device, various optical films (retardation plate, A brightness enhancement film or the like) is used.

The polarizing plate and the optical film are bonded to the liquid crystal cell using a pressure-sensitive adhesive. As the pressure sensitive adhesive, an acrylic pressure sensitive adhesive based on an acrylic polymer having excellent adhesiveness and transparency is often used. The crosslinking of the acrylic pressure-sensitive adhesive utilizes the bonding of the crosslinking agent and the functional monomer of the acrylic polymer.

However, in a liquid crystal cell including a metal layer such as ITO, corrosion is generated by H ₂ O and O ₂ contained in the pressure-sensitive adhesive, and metal oxides, hydroxides, and other corrosive products are formed. These may lower the electrical or mechanical stability of the liquid crystal display device, and may cause problems in securing visibility and reliability.

In particular, such problems can be exacerbated by exposure to high temperature and high humidity environments.

In order to improve the corrosion resistance of metal, the use of a hydrogen ion generating monomer (e.g., a monomer having a carboxyl group), which is essentially used for improving the durability of the pressure-sensitive adhesive composition, is excluded.

However, in recent years, the thickness of the polarizer protective film becomes thin due to the tendency of the polarizer to be thinned, and the function of the polarizer protective film, which suppresses the shrinkage of the polarizer, is lacking. Accordingly, there is a growing demand to improve the durability of the pressure-sensitive adhesive bonding the polarizer and the polarizer protective film to compensate for the deficient role of the polarizer protective film.

In this connection, there has been proposed a method for improving the durability by adding a compound capable of improving the cohesion or cross-linking force of the copolymer simultaneously with the exclusion of the hydrogen ion generating monomer (Korean Patent Publication No. 2010-0113487, 2010- 0109373). However, this method shows a durability improvement effect which is insufficient to satisfy the role of the polarizer protective film.

The present invention provides an acrylic copolymer and a pressure-sensitive adhesive composition which can effectively prevent corrosion of a metal layer without using a separate corrosion inhibitor component and can suppress shrinkage of a polarizer due to excellent adhesion durability under high temperature or high temperature and high humidity conditions It has its purpose.

In order to achieve the above object, the present invention provides an acrylic copolymer containing a compound represented by the following general formula (1).

(Wherein R ₁ is hydrogen or a methyl group, R ₂ is an alkylene group having 1 to 10 carbon atoms, and X is O or NH).

Preferably, R ₂ in Formula 1 may be an alkylene group having 1 to 4 carbon atoms.

The acrylic copolymer may contain a (meth) acrylate monomer having an alkyl group of 1-12 carbon atoms and a compound of the formula (1).

May contain 1 to 20 parts by weight of the compound of the formula (1) based on 100 parts by weight of the (meth) acrylate monomer having the alkyl group having 1-12 carbon atoms.

The acrylic copolymer may have a weight average molecular weight (Mw in terms of polystyrene) of 50,000 to 200.

The present invention also provides a pressure-sensitive adhesive composition containing the acrylic copolymer.

The pressure-sensitive adhesive composition of the present invention has an advantage that it can effectively inhibit the corrosion of the metal layer without containing any corrosion inhibitor component.

In addition, the pressure-sensitive adhesive composition of the present invention is excellent in adhesion to a metal layer, has excellent adhesion durability under high temperature or high temperature and high humidity conditions, and can compensate for the shortage of the role of the polarizer protective film (for example, shrinkage of the polarizer) There is an advantage.

Therefore, the pressure-sensitive adhesive composition is expected to be highly utilized in the field of electric / electronic parts where a large amount of bonding of a metal or a metal oxide semiconductor is required.

The present invention relates to an acrylic copolymer excellent in corrosion resistance and adhesion durability of a metal and a pressure-sensitive adhesive composition containing the acrylic copolymer.

Hereinafter, the present invention will be described in detail.

The acrylic copolymer of the present invention contains a compound represented by the following general formula (1).

[Chemical Formula 1]

(Wherein R ₁ is hydrogen or a methyl group, R ₂ is an alkylene group having 1 to 10 carbon atoms, and X is O or NH).

Preferably, R ₂ in Formula 1 is an alkylene group having 1 to 4 carbon atoms.

The compound of Formula 1 is a compound having a cyclic urea group, and the urea bond is induced by the cyclic urea group. Such urea bond is formed at the time of reaction with the crosslinking agent contained in the pressure-sensitive adhesive composition to improve the cohesive force of the pressure-sensitive adhesive composition, so that the adhesive strength to the metal layer, in particular, the adherence resistance under adverse conditions (high temperature or high temperature and high humidity conditions) can be excellent.

In addition, corrosion of the metal layer can be suppressed because acrylic acid, which is generally used for improving adhesion durability, is excluded.

These compounds of the formula (1) can be synthesized or commercially available products. A commercially available WAM series from Rhodia is available. Among them, it is preferable to use WAM E, WAM II having compatibility with a ketone-based organic solvent.

The acrylic copolymer of the present invention preferably contains a (meth) acrylate monomer having an alkyl group having from 1 to 12 carbon atoms and a compound represented by the above formula (1). Here, (meth) acrylate means acrylate and methacrylate.

Examples of the (meth) acrylate monomer having an alkyl group having 1-12 carbon atoms include n-butyl (meth) acrylate, 2-butyl (meth) acrylate, (Meth) acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (Meth) acrylate, n-butyl acrylate, nonyl (meth) acrylate, decyl (meth) acrylate and lauryl Or a mixture thereof. These may be used alone or in combination of two or more.

The compound of Formula 1 is a compound having a cyclic urea group which is a crosslinkable functional group. The compound of formula (1) is preferably contained in an amount of 1 to 20 parts by weight, more preferably 1 to 10 parts by weight, based on 100 parts by weight of the (meth) acrylate monomer having an alkyl group having 1-12 carbon atoms. When the content is less than 1 part by weight, the effect of improving corrosion resistance and durability may be insufficient. When the content is 20 parts by weight, compatibility with an organic solvent is lowered and it is difficult to use it as a pressure-sensitive adhesive.

In addition, the acrylic copolymer of the present invention may further contain a polymerizable monomer having a crosslinkable functional group in addition to the compound represented by the above formula (1). The added polymerizable monomer having a crosslinkable functional group can impart durability and cutability by reinforcing the cohesive strength or adhesive strength of the pressure-sensitive adhesive composition by chemical bonding, and a component that does not generate hydrogen ions (H ⁺ ) is used .

Examples of the polymerizable monomer having a crosslinkable functional group include a monomer having a hydroxy group, a monomer having an amide group, and a monomer having a tertiary amine group, and these may be used alone or in combination of two or more.

Examples of the monomer having a hydroxy group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl Hydroxypropyleneglycol (meth) acrylate, hydroxyalkylene glycol having 2 to 4 carbon atoms in the alkylene group (e.g., methoxyethyl (meth) acrylate, Hydroxybutyl vinyl ether, 8-hydroxyoctyl vinyl ether, 9-hydroxynonyl (meth) acrylate, 4-hydroxybutyl vinyl ether, Vinyl ether, and 10-hydroxydecyl vinyl ether, among which 4-hydroxybutyl vinyl ether is preferable.

Examples of the monomer having an amide group include (meth) acrylamide, N-isopropyl acrylamide, N-tertiary butyl acrylamide, 3-hydroxypropyl (meth) acrylamide, 4-hydroxybutyl (Meth) acrylamide, 8-hydroxyoctyl (meth) acrylamide, and 2-hydroxyethylhexyl (meth) acrylamide. Of these, (meth) acrylamide is preferable.

Examples of the monomer having a tertiary amine group include N, N- (dimethylamino) ethyl (meth) acrylate, N, N- (diethylamino) ethyl (meth) Methacrylate, and the like.

The polymerizable monomer having such a crosslinkable functional group is preferably contained in an amount of 0.05 to 10 parts by weight, more preferably 0.1 to 8 parts by weight, per 100 parts by weight of the (meth) acrylate monomer having an alkyl group having 1-12 carbon atoms good. When the content is less than 0.05 part by weight, the cohesive force of the pressure-sensitive adhesive becomes small and durability may be deteriorated. When the content is more than 10 parts by weight, a high gel fraction may lower the adhesive strength and cause durability problems.

The acrylic copolymer of the present invention may further contain other polymerizable monomers other than the above monomers in a range not lowering the adhesive force, for example, 10 parts by weight or less based on the total amount.

The method for producing the copolymer is not particularly limited and can be produced by methods such as bulk polymerization, solution polymerization, emulsion polymerization or suspension polymerization, which are commonly used in the art, and solution polymerization is preferable. In addition, a solvent, a polymerization initiator, a chain transfer agent for molecular weight control and the like which are usually used in polymerization can be used.

The acrylic copolymer preferably has a weight average molecular weight (polystyrene conversion, Mw) of 50,000 to 2,000,000, more preferably 400,000 to 2,000,000 as measured by Gel Permeation Chromatography (GPC). When the weight-average molecular weight is less than 50,000, cohesion between co-polymers may be insufficient, which may cause problems in adhesion durability. If the weight average molecular weight is more than 2,000,000, a large amount of a diluting solvent may be required in order to ensure fairness in coating.

The present invention is characterized by a pressure-sensitive adhesive composition containing the acrylic copolymer. The pressure-sensitive adhesive composition may further contain a crosslinking agent.

The crosslinking agent can improve the adhesion and durability, and can maintain the reliability at a high temperature and the shape of the pressure-sensitive adhesive.

The cross-linking agent may be an isocyanate-based, epoxy-based, melamine-based, peroxide-based, metal chelating-based, oxazoline-based, or the like. Preferred is a double isocyanate-based or epoxy-based.

Examples of the isocyanate-based isocyanate include isocyanate-based compounds such as tolylene diisocyanate, xylene diisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tetramethyl xylene diisocyanate, Diisocyanate compounds such as isocyanate; An adduct obtained by reacting 3 moles of a diisocyanate compound with 1 mole of a polyhydric alcohol compound such as trimethylolpropane, an isocyanurate compound in which 3 moles of a diisocyanate compound is self-condensed, a diisocyanate obtained from 2 moles of 3 moles of a diisocyanate compound And multifunctional isocyanate compounds containing three functional groups such as burette, triphenylmethane triisocyanate and methylene bistriisocyanate in which the remaining one mole of diisocyanate is condensed in urea.

The epoxy system may be an ethylene glycol diglycidyl ether, a diethylene glycol diglycidyl ether, a polyethylene glycol diglycidyl ether, a propylene glycol diglycidyl ether, a tripropylene glycol diglycidyl ether, a polypropylene glycol di Hexanediol diglycidyl ether, polytetramethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, diethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, Glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, resorcinol diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, trimethylol propane triglycidyl ether, pentaerythritol poly Glycidyl ether, sorbitol polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, tris (glycidyl) isocyanurate N, N, N ', N'-tetraglycidyl-m-hexyldicyclohexyl) isocyanurate, 1,3-bis (N, N-glycidylaminomethyl) cyclohexane, Xylylenediamine, and the like.

Examples of the melamine type include hexamethylol melamine, hexamethoxymethyl melamine, and hexabutoxymethyl melamine.

Such a crosslinking agent may be contained in an amount of 0.1 to 15 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the acrylic copolymer. If the content is less than 0.1 part by weight, the cohesive strength may be decreased due to insufficient crosslinking, which may deteriorate the durability of the adhesive durability and the cutability. If the content is more than 15 parts by weight, the residual stress due to the excessive crosslinking reaction may be deteriorated.

In addition to the above components, the pressure-sensitive adhesive composition may further contain various additives such as a silane coupling agent, a tackifier resin, an antioxidant, a leveling agent, a surface lubricant, a dye, A pigment, a defoaming agent, a filler, a light stabilizer, an antistatic agent, and the like.

The double silane coupling agent is preferably contained in order to improve adhesion between the pressure-sensitive adhesive and the base material. It is preferable that the double silane coupling agent contains an alkoxysilane containing a functional group such as amino group, epoxy group, acetoacetyl group, polyalkylene glycol group, acrylic group, Can be used.

The amount of such an additive may be suitably controlled within a range that does not impair the effect of the present invention. For example, the silane coupling agent may be contained in an amount of 0.1 to 2 parts by weight based on 100 parts by weight of the acrylic copolymer in consideration of adhesion strength and durability have.

The pressure-sensitive adhesive composition of the present invention can be used particularly as a pressure-sensitive adhesive for a polarizing plate or a pressure-sensitive adhesive for a surface protective film for bonding with a liquid crystal cell. It can be used not only as a protective film, a reflective sheet, a structural adhesive sheet, a photographic adhesive sheet, a lane marking adhesive sheet, an optical adhesive product, an electronic component adhesive, but also a general commercial adhesive sheet product.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Manufacturing example  1: Production of acrylic copolymer

A monomer mixture having the composition shown in the following Table 1 was put into a 1 L reactor equipped with a cooling device for regulating the temperature of the nitrogen gas and refluxing, and then 100 parts by weight of acetone was added as a solvent. Nitrogen gas was then purged for 1 hour to remove oxygen and then maintained at 62 ° C. After the mixture was homogenized, 0.07 part by weight of azobisisobutyronitrile (AIBN) was added as a reaction initiator and reacted for 6 hours to prepare an acrylic copolymer having a weight average molecular weight of about 1,000,000.

Example  1-9 and Comparative Example  1-2

As shown in Table 1, an acrylic copolymer, a crosslinking agent and a silane coupling agent of the production examples were mixed and diluted in an organic solvent to prepare a pressure-sensitive adhesive composition.

division
(Parts by weight) Acrylic copolymer Crosslinking agent ^{1 )} Silane
Coupling agent ^{2 )} acryl
Rate
Monomer Polymerizable
Monomer Formula 1
BA MA AA 2HEA A-1 A-2 B-1 B-2 B-3 Example 1 90 9 - - One One - - 0.5 Example 2 89 9 - - 2 One - - 0.5 Example 3 86 9 - - 5 One - - 0.5 Example 4 81 9 - - 10 One - - 0.5 Example 5 71 9 - - 20 One - - 0.5 Example 6 90 9 - - - One One - - 0.5 Example 7 89 9 - One One - One - - 0.5 Example 8 90 9 - - One - One - 0.5 Example 9 90 9 - One 0.5 - 0.5 0.5 Comparative Example 1 90 9 - One - One - - 0.5 Comparative Example 2 85 9 5 One - - One - - 0.5 BA: butyl acrylate
MA: methyl acrylate
AA: Acrylic acid
2HEA: 2-hydroxyethyl acrylate
A-1: WAM E product (Rhodia)
A-2: WAM Ⅱ product (Rhodia)
B-1: Cor-L, Coronate-L (a tolylene diisocyanate adduct of trimethylol propane, manufactured by Nippon Polyurethane Kogyo Co., Ltd.)
B-2: Cor-HXR, Coronate-HXR (HDI isocyanurate, manufactured by Nippon Polyurethane Kogyo Co., Ltd.)
B-3: melamine-based, hexamethylol melamine (Waterstone Technology, LLC)
Silane coupling agent: 3-glycidoxypropyltrimethoxysilane, KBM-403 (Shin-Etsu)
1) and 2): The content of the crosslinking agent and the silane coupling agent is about 100 parts by weight of the acrylic copolymer

The pressure-sensitive adhesive composition prepared above was applied on a release film coated with silicone release agent to a thickness of 25 탆 and dried at 100 캜 for 1 minute to form an adhesive layer.

The pressure-sensitive adhesive layer prepared above was laminated on an iodine-based polarizing plate having a thickness of 185 탆 by pressure-sensitive adhesive processing to produce a polarizer with a pressure-sensitive adhesive. The prepared polarizing plate was stored for a curing period under the conditions of 23 캜 and 60% RH.

Test Example

The properties of the pressure-sensitive adhesive composition and the polarizer with a pressure-sensitive adhesive prepared in the above Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 2 below.

One. Metal layer Corrosion resistance

After the release film of the polarizing plate with the adhesive was peeled off, the surface of the pressure-sensitive adhesive layer was bonded to the aluminum plate, and the sample was allowed to stand for 250 hours in an atmosphere of 60 ° C and 95% RH.

The pressure-sensitive adhesive layer was peeled from the laminate, and the surface of the aluminum plate in contact with the pressure-sensitive adhesive layer was visually observed to evaluate the presence or absence of corrosion.

<Evaluation Criteria>

Aluminum plate surface does not corrode at all: ○

Corrosion of aluminum plate surface: x

2. Adhesion to metal layer (N / 25mm)

After the release film of the polarizing plate with the adhesive was peeled off, the surface of the adhesive layer was bonded to the aluminum plate. The autoclave treatment was performed at 50 캜 and 5 kg / cm 2 (490.3 ㎪) for 20 minutes. Thereafter, the sample was allowed to stand in an atmosphere of 23 DEG C and 50RH% for 24 hours to prepare a laminate specimen.

The polarizing plate was peeled from the laminate at a speed of 300 mm / min and in a direction of 180 ° to measure the adhesive strength.

3. Metal layer  Adhesive durability

After the release film of the polarizing plate with the adhesive was peeled off, the surface of the adhesive layer was bonded to the aluminum plate. The autoclave treatment was performed at 50 캜 and 5 kg / cm 2 (490.3 ㎪) for 20 minutes. Thereafter, the sample was allowed to stand in an atmosphere of 23 DEG C and 50RH% for 24 hours to prepare a laminate specimen.

Thereafter, the above-mentioned laminate specimen was stored for 300 hours under a drying condition at a temperature of 80 캜, and then the appearance thereof was confirmed (heat resistance test).

<Evaluation Criteria>

Bubbles and peeling phenomenon are observed: x

Bubbles and peeling phenomenon are observed: ○

division Corrosion resistance adhesiveness
(N / 25 mm) Adhesive durability Example 1 ○ 2 ○ Example 2 ○ 3 ○ Example 3 ○ 5 ○ Example 4 ○ 7 ○ Example 5 ○ 8 ○ Example 6 ○ 2 ○ Example 7 ○ 3 ○ Example 8 ○ 4 ○ Example 9 ○ 4 ○ Comparative Example 1 ○ 1.5 × Comparative Example 2 × 8 ○

As shown in Table 2, it was confirmed that the pressure-sensitive adhesive compositions of Examples 1 to 9 containing the compound of Formula 1 according to the present invention were superior in corrosion resistance as well as adhesion durability of the metal layer as compared with Comparative Examples 1 and 2.

Claims (7)

An acrylic copolymer containing a compound of the following formula (1) and containing no hydrogen ion generating monomer:
[Chemical Formula 1]

(Wherein R ₁ is hydrogen or a methyl group, R ₂ is an alkylene group having 1 to 10 carbon atoms, and X is O or NH).
The acrylic copolymer according to claim 1, wherein R ₂ in the formula (1) is an alkylene group having 1 to 4 carbon atoms.
The acrylic copolymer according to claim 1, wherein the acrylic copolymer contains a (meth) acrylate monomer having an alkyl group of 1-12 carbon atoms and a compound of the formula (1).
4. The acrylic copolymer according to claim 3, which comprises 1 to 20 parts by weight of the compound of the formula (1) based on 100 parts by weight of the (meth) acrylate monomer having the alkyl group having 1-12 carbon atoms.
The acrylic copolymer according to claim 1, wherein the acrylic copolymer has a weight average molecular weight (Mw in terms of polystyrene) of 50,000 to 2,000,000.
A pressure-sensitive adhesive composition containing the acrylic copolymer according to any one of claims 1 to 5. A pressure-sensitive adhesive composition comprising an acrylic copolymer containing a compound of the following formula (1), for bonding between a polarizing plate and a liquid crystal cell, for a polarizing plate surface protective film or for bonding between a polarizing plate and a polarizing protective film:
[Chemical Formula 1]

(Wherein R1 is hydrogen or a methyl group, R2 is an alkylene group having 1 to 10 carbon atoms, and X is O or NH).