KR20150039984A - Adhesive composition - Google Patents

Abstract

The present invention relates to an adhesive composition, and more specifically, to an adhesive composition containing an acrylic copolymer including a (metha)acrylate monomer having an alkyl group of 1-12 carbon atoms, and a polymerizable monomer which does not generate hydrogen ion (H+); and an ammonium-based ionic polyfunctional acrylate of chemical formula 1. The adhesive composition has no phenomena such as excitation, bubble, and delamination caused by superficial transition of an antistatic agent, has excellent durability as cohesiveness is improved and satisfies antistatic properties, and does not contain an extra corrosion-proof agent and effectively inhibits corrosion of a metal layer. In the chemical formula 1, R is a direct bond or an alkyl group of C1-C6.

Description

[0001] ADHESIVE COMPOSITION [0002]

The present invention relates to a pressure-sensitive adhesive composition which does not contain an acid having excellent durability.

2. Description of the Related Art Generally, a liquid crystal display device (LCD) is provided with a liquid crystal cell containing a liquid crystal and a polarizer, and a suitable adhesive layer is used to bond the liquid crystal cell. As the pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive based on an acrylic copolymer having excellent tackiness and transparency is often used.

When the releasing film is peeled off from the pressure-sensitive adhesive layer in the process of attaching the polarizing plate to the liquid crystal cell, static electricity is generated, and the generated static electricity affects the orientation of the liquid crystal to cause defects or to be introduced between the liquid crystal cell and the pressure- It causes pollution by foreign matter.

In order to solve this problem, an ionic antistatic agent is mixed in a pressure-sensitive adhesive composition. However, bleed-out phenomenon precipitated by surface migration of the ionic antistatic agent may cause lifting, bubbling and peeling. In particular, such problems can be exacerbated by exposure to high temperature and high temperature and high humidity environments.

Accordingly, there has been proposed a method of using an acrylic copolymer having an amine group or a polyethylene glycol group introduced therein to increase the compatibility with an ionic antistatic agent (Korean Patent Laid-Open Nos. 2009-132564 and 2011-136760).

However, the method is insufficient to improve the durability due to the bleed-out phenomenon, and the cohesive force is low, so that bubbles are generated or the amount of the pressure-sensitive adhesive is increased.

An object of the present invention is to provide a pressure-sensitive adhesive composition which is free from lifting, bubbling and peeling due to surface migration of an ionic antistatic agent and has improved cohesive strength, as well as durability and antistatic property.

Another object of the present invention is to provide a pressure-sensitive adhesive composition which can effectively inhibit corrosion of a metal layer without containing a corrosion inhibitor component separately.

In order to achieve the above object, the present invention provides an acrylic copolymer containing (meth) acrylate monomer having an alkyl group having 1-12 carbon atoms and a polymerizable monomer not generating a hydrogen ion (H ⁺ ); And an ammonium-based ionic polyfunctional acrylate represented by the following formula (1):

(In the above formula, wherein R is a direct bond or an alkyl group of C ₁ -C _6).

Preferably, Formula 1 may be represented by Formula 2 or Formula 3 below.

The ionic polyfunctional acrylate may be contained in an amount of 1 to 30 parts by weight based on 100 parts by weight of the acrylic copolymer.

The polymerizable monomer that does not generate the hydrogen ion (H ⁺ ) may be at least one member selected from the group consisting of a monomer having a hydroxyl group, a monomer having an amide group, and a monomer having a tertiary amine group.

The pressure-sensitive adhesive composition may further contain a crosslinking agent.

The pressure-sensitive adhesive composition of the present invention is free from lifting, bubbling and peeling due to migration of the surface of an antistatic agent, has improved cohesion and durability, and has antistatic properties.

Further, the pressure-sensitive adhesive composition of the present invention does not contain an acid, and does not contain a corrosion inhibitor component separately, and has an advantage that corrosion of a metal layer can be effectively suppressed.

Therefore, it is expected that the above-mentioned pressure-sensitive adhesive composition will be highly utilized for the purpose of avoiding static electricity in the fields of plastic products, especially electric / electronic devices, where static electricity is easily generated.

The present invention relates to a pressure-sensitive adhesive composition which does not contain an acid having excellent durability.

Hereinafter, the present invention will be described in detail.

The pressure-sensitive adhesive composition of the present invention contains an acrylic copolymer and an ammonium-based ionic polyfunctional acrylate represented by the following general formula (1).

[Chemical Formula 1]

(In the above formula, wherein R is a direct bond or an alkyl group of C ₁ -C _6).

The ionic polyfunctional acrylate of the present invention has an antistatic property and can improve the polarity of the copolymer by incorporating an ionic functional group in the molecule to thereby improve the bleed out phenomenon The durability is improved.

In addition, the ammonium-based ionic polyfunctional acrylate of the above formula (1) simultaneously acts as a crosslinking agent for bundling a copolymer to improve cohesion and improve durability.

In addition, since the present invention can exhibit sufficient durability without using an acid component which is conventionally used for ensuring durability, corrosion of the metal by the acid component does not occur.

The acrylic copolymer having an epoxy group of the present invention preferably contains a (meth) acrylate monomer having an alkyl group of 1-12 carbon atoms and a polymerizable monomer having a crosslinkable functional group. In the present invention, (meth) acrylate means acrylate and methacrylate, and the content is based on the solid content

Examples of the (meth) acrylate monomer having an alkyl group having 1-12 carbon atoms include (meth) acrylates derived from an aliphatic alcohol having 1 to 12 carbon atoms, such as methyl acrylate, ethyl acrylate, propyl acrylate, (meth) acrylate, n-butyl (meth) acrylate, 2-butyl (meth) acrylate, t- (Meth) acrylate, decyl (meth) acrylate, and lauryl (meth) acrylate. These may be used alone or in combination of two or more. Of these, n-butyl acrylate, 2-ethylhexyl acrylate or a mixture thereof is preferable.

The polymerizable monomer having a cross-linkable 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 ion (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, the adhesive strength may be lowered and the durability may be deteriorated due to a high gel fraction.

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 ammonium-based ionic polyfunctional acrylate may be represented by the following general formula (2) or (3).

(2)

(3)

The ammonium ionic polyfunctional acrylate may be a commercially available product or a product synthesized by a general method.

As an example, the ionic polyfunctional acrylates of the present invention can be prepared by performing a substitution reaction of trihydroxyalkylamine with an acryl halide followed by addition reaction of an alkyl halide.

The ionic polyfunctional acrylate is preferably contained in an amount of 1 to 30 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of the acrylic copolymer. When the content is less than 1 part by weight, the effect of improving the cohesive force and the effect of suppressing the bleed-out of the antistatic agent are insufficient. When the content is more than 30 parts by weight, there is a fear of haze due to moisture in the moisture-

The pressure-sensitive adhesive composition of the present invention 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, an antioxidant, and the like in order to control the adhesion, cohesion, viscosity, A pigment, a defoaming agent, a filler, a light stabilizer, and the like. At this time, it is preferable not to add an antistatic agent.

Such an additive can appropriately control the content within a range that does not impair the effect of the present invention.

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: Acrylic copolymer

88 parts by weight of n-butyl acrylate (BA), 10 parts by weight of methyl acrylate (MA) and 2 parts by weight of 2-hydroxyethyl acrylate (2) were added to a 1 L reactor equipped with a cooling device , And 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.

Manufacturing example  2: Ammonium ionic Polyfunctional acrylate

Manufacturing example  2-1

Triethanolamine (75 g, 0.5 mol) was added to a 1 L reactor equipped with a cooling device so that the nitrogen gas was refluxed and the temperature thereof was easily controlled. Anhydrous pyridine (500 mL) was added as a solvent and dissolved by stirring. Acryloyl chloride (150 g, 1.67 mol) was added dropwise at room temperature for 1 hour using a dropping funnel. After stirring at room temperature for 5 hours, 1 L of distilled water and 1 L of toluene were used to separate the aqueous layer and the toluene layer. The obtained toluene layer was distilled to remove the solvent to obtain a compound of Formula 4 (crude 150 g).

Anhydrous tetrahydrofuran (500 mL) was added to the compound of Formula 4 to dissolve it, and methyl iodide (71 g) was added dropwise at room temperature for 1 hour using a dropping funnel. The mixture was stirred at room temperature for 5 hours, and the solvent in the reaction mixture was distilled off to obtain 450 g of the compound of formula (2). The reaction formula is shown below, and it was found by NMR measurement that the compound has the structure of the following formula (2).

_{^{1 H-NMR (CDCl 3,}} 300 MHz): δ6.34 (3H), 6.02 (3H), 5.81 (3H), 4.60 (6H), 4.17 (6H), 3.50 (3H)

Manufacturing example  2-2

(490 g, crude) was obtained in the same manner as in Preparation Example 2-1, but using the following reaction scheme. The reaction formula is as shown below, and it was found by NMR measurement that the compound had the structure of the above-mentioned formula (3).

_{^{1 H-NMR (CDCl 3,}} 300 MHz): δ6.28 (3H), 5.98 (3H), 5.75 (3H), 4.15 (6H), 3.30 (3H), 3.24 (6H), 2.01 (6H)

Example  1-6 and Comparative Example  1-4

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

division
(Parts by weight) Production Example 1 Ionic
Polyfunctional acrylate Antistatic agent Silane
Coupling agent Cross-linking agent A-1 A-2 A-3 A-4 A-5 Example 1 100 10 - - - - 0.5 - Example 2 100 - 10 - - - 0.5 - Example 3 100 2 - - - - 0.5 0.5 Example 4 100 5 - - - - 0.5 - Example 5 100 20 - - - - 0.5 - Example 6 100 30 - - - - 0.5 - Example 7 100 10 - 2 - - 0.5 - Example 8 100 10 - 2 - - 0.5 0.5 Comparative Example 1 100 - - 2 - - 0.5 0.5 Comparative Example 2 100 - - - 2 - 0.5 0.5 Comparative Example 3 100 - - - - 2 0.5 0.5 Comparative Example 4 100 - - 2 - - 0.5 -

A-2:

A-3:

A-4:

A-5: NaPF₆ Crosslinking agent: Coronate-L (TDI crosslinking agent, CORONATE-L, Japan Urethane Industry)
Silane coupling agent: 3- (trimethoxysilyl) propyl-3-oxobutaethioate
A-1:

A-2:

A-3:

A-4:

A-5: NaPF ₆

The pressure-sensitive adhesive composition prepared above was cured on a releasing film coated with silicone release agent to a thickness of 25 mu m, and dried at 100 DEG C for 1 minute, 5 minutes and 10 minutes to form an adhesive layer.

A polarizing plate having a triacetyl cellulose protective film bonded to both sides of the polarizer was laminated on the pressure-sensitive adhesive layer to prepare a polarizing plate with a pressure-sensitive adhesive. At this time, the protective film surface and the adhesive layer were laminated so as to be in contact with each other. The prepared polarizing plate was stored for a curing period under conditions of 23 캜 and 60% RH

Test Example

The physical properties of 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.

1. Adhesive strength (N / 25 mm)

The prepared polarizer with a pressure-sensitive adhesive was cut into a size of 25 mm x 100 mm, and the release film was peeled off. The release film was laminated to a glass substrate (# 1737, Corning) at a pressure of 0.25 MPa and autoclaved. The adhesive strength at room temperature was measured by peeling the pressure-sensitive adhesive layer at a peeling speed of 300 mm / min and a peeling angle of 180 ° using a universal tensile tester (UTM, Instron) after the prepared specimens were left under the conditions of 23 ° C. and 50% RH for 24 hours Respectively. At this time, measurement was carried out under conditions of 23 캜 and 50% RH.

2. Durability (heat resistance, Wet heat )

The prepared polarizer with a pressure-sensitive adhesive was cut into a size of 90 mm × 170 mm, and the release film was peeled off. Then, the optical absorption axis was perpendicularly attached to both sides of the glass substrate (110 mm × 190 mm × 0.7 mm). At this time, the applied pressure was 5 kg / cm < 2 >, and the clean room operation was performed so that bubbles or foreign matter would not occur. The heat resistance characteristics were evaluated by observing the occurrence of bubbles or peeling after being left at a temperature of 80 ° C. for 1000 hours. The moisture resistance characteristics were evaluated by observing the occurrence of bubbles or peeling after being left at a temperature of 60 ° C. and 90% RH for 1000 hours Respectively. At this time, the sample was allowed to stand at room temperature for 24 hours immediately before evaluating the state of the specimen.

<Evaluation Criteria>

Ⓞ: No bubbles or peeling.

○: Bubbles or peeling <5

?: 5 pieces? Bubbles or peeling <10 pieces

X: 10 pieces &lt; bubble or peeling or haze is visually recognized.

3. Surface resistivity (Ω / □)

The prepared polarizer plate with a pressure-sensitive adhesive was measured 10 times at three points of the pressure-sensitive adhesive layer using a surface resistance meter (MCP-HT450, Mitsubishi Chemical Co., Ltd.) and expressed as an average value thereof.

Thereafter, the polarizing plate with a pressure-sensitive adhesive was allowed to stand at 60 DEG C for 24 hours and then measured in the same manner as above.

division adhesiveness
(N / 25 mm) Heat resistance Humidity Durability Surface resistivity Example 1 2.5 Ⓞ Ⓞ 3X10 ¹⁰ Example 2 3.0 Ⓞ Ⓞ 6X10 ¹⁰ Example 3 2.0 ○ Ⓞ 5X10 ¹¹ Example 4 2.4 ○ Ⓞ 1X10 ¹¹ Example 5 3.2 Ⓞ ○ 1X10 ¹⁰ Example 6 4.1 Ⓞ ○ 8X10 ⁹ Example 7 3.1 Ⓞ Ⓞ 5X10 ⁹ Example 8 3.4 Ⓞ Ⓞ 6X10 ⁹ Comparative Example 1 1.2 △ ○ 7X10 ¹⁰ Comparative Example 2 1.6 △ ○ 1X10 ¹¹ Comparative Example 3 1.8 × × 8X10 ¹⁰ Comparative Example 4 5.9 × × 6X10 ¹⁰

As shown in Table 2, it was confirmed that the pressure-sensitive adhesive compositions of Examples 1 to 8 according to the present invention had better adhesion, durability, and heat and humidity resistance than Comparative Examples 1 to 4, and also antistatic properties could be satisfied.

Claims (5)

An acrylic copolymer containing a (meth) acrylate monomer having an alkyl group having 1-12 carbon atoms and a polymerizable monomer not generating a hydrogen ion (H ⁺ ); And
A pressure-sensitive adhesive composition comprising an ammonium-based ionic polyfunctional acrylate represented by the following formula (1):
[Chemical Formula 1]

(In the above formula, wherein R is a direct bond or an alkyl group of C ₁ -C _6).
The hard coating composition according to claim 1, wherein the formula (1) is represented by the following formula (2) or (3)
(2)

(3)

The pressure-sensitive adhesive composition according to claim 1, wherein the ionic polyfunctional acrylate is contained in an amount of 1 to 30 parts by weight based on 100 parts by weight of the acrylic copolymer.
The pressure-sensitive adhesive composition according to claim 1, wherein the polymerizable monomer which does not generate the hydrogen ion (H ⁺ ) is at least one selected from the group consisting of a monomer having a hydroxyl group, a monomer having an amide group and a monomer having a tertiary amine group.
The pressure-sensitive adhesive composition according to claim 1, wherein the pressure-sensitive adhesive composition further comprises a crosslinking agent.