WO2014038811A1 - Adhesive composition - Google Patents

Abstract

The present invention relates to an adhesive composition, and more particularly to an adhesive composition having excellent durability and an anti-static property and which effectively suppresses the corrosion of a metal layer without containing an additional anti-corrosive agent in that it contains an acryl-based copolymer containing an ionic monomer having a vinyl group and an ionic anti-static agent in order to avoid conditions such as detachment, foaming, and exfoliation due to the surface transition of the anti-static agent.

Description

Pressure-sensitive adhesive composition

The present invention improves the compatibility between the antistatic agent and the acrylic copolymer containing no acid, thereby suppressing the bleed out of the antistatic agent, thereby improving the durability, antistatic property and corrosion resistance at the same time. It is about.

In general, a liquid crystal display device (LCD) is provided with a liquid crystal cell and a polarizing plate containing a liquid crystal, and an appropriate pressure-sensitive adhesive layer for bonding them is used. The pressure sensitive adhesive is often used an acrylic pressure sensitive adhesive based on an acrylic copolymer having excellent adhesiveness and transparency.

In the process of attaching the polarizing plate to the liquid crystal cell, peeling the release film from the pressure-sensitive adhesive layer generates static electricity. The generated static electricity affects the alignment of the liquid crystal and causes defects or flows between the liquid crystal cell and the adhesive due to electrostatic attraction. It causes contamination by foreign objects.

In order to improve this, an ionic antistatic agent is mixed and used in the pressure-sensitive adhesive composition, but a bleed out phenomenon that precipitates due to the surface migration of the ionic antistatic agent may cause lifting, bubbles, and peeling. In particular, this problem may be exacerbated when exposed to a high temperature or high temperature and high humidity environment.

In addition, the liquid crystal cell including a metal layer such as ITO is corroded by H ₂ O and O ₂ contained in the pressure-sensitive adhesive to form metal oxides, hydroxides, and other corrosive products. These may reduce the electrical or mechanical stability of the liquid crystal display, or may cause problems in securing visibility and reliability.

In order to improve the corrosiveness of metals, there is a tendency to exclude the use of hydrogen ion generating monomers (eg, monomers having a carboxyl group) which are essentially used for improving durability of the pressure-sensitive adhesive composition.

As mentioned above, the demand for the adhesive composition excellent in antistatic property and durability is increasing recently, without using a hydrogen ion generating monomer.

In this regard, a method of using an acryl-based copolymer having increased compatibility with an antistatic agent by introducing an amine group or a polyethylene glycol group while excluding a hydrogen ion generating monomer has been proposed (Korean Patent Publication No. 2009-132564, 1). 2011-136760).

However, this method is a situation that the effect is insufficient to improve the durability degradation due to the bleed out phenomenon.

The present invention is excellent in durability as well as antistatic properties because there is no phenomenon such as lifting, bubbles and peeling due to the surface migration of the antistatic agent, and does not contain a corrosion inhibitor component and can effectively suppress the corrosion of the metal layer. The purpose is to provide.

In order to achieve the above object, the present invention provides an adhesive composition containing an acrylic copolymer containing an ionic monomer having a vinyl group, and an ionic antistatic agent.

The ionic monomer having a vinyl group

or

Can be.

The acrylic copolymer may contain a (meth) acrylate monomer having an alkyl group having 1 to 12 carbon atoms and an ionic monomer having a vinyl group.

The ionic monomer having a vinyl group may contain 0.1 to 10 parts by weight based on 100 parts by weight of the (meth) acrylate monomer having an alkyl group having 1 to 12 carbon atoms.

The ionic antistatic agent is a cation selected from the group consisting of alkali metal salts, ammonium salts, sulfonium salts and phosphonium salts; It may be an ionic salt consisting of an anion selected from the group consisting of fluorine-containing inorganic salts, fluorine-containing organic salts and iodine ions.

The ionic antistatic agent may contain 0.1 to 5 parts by weight based on 100 parts by weight of the acrylic copolymer.

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

The pressure-sensitive adhesive composition of the present invention does not have a phenomenon such as lifting, bubbles, and peeling due to the surface migration of the antistatic agent, which is excellent in durability and at the same time has an advantage of satisfying the antistatic property.

The pressure-sensitive adhesive composition of the present invention has an advantage of effectively suppressing corrosion of the metal layer without separately containing a corrosion inhibitor component.

Therefore, the pressure-sensitive adhesive composition is expected to have high utility for anti-static applications in the fields of plastic products, especially electrical / electronic devices, which tend to generate static electricity.

The present invention improves the compatibility between the antistatic agent and the acrylic copolymer containing no acid, thereby suppressing the bleed out of the antistatic agent, thereby improving the durability, antistatic property and corrosion resistance at the same time. It is about.

Hereinafter, the present invention will be described in detail.

The adhesive composition of this invention contains the acrylic copolymer containing the ionic monomer which has a vinyl group, and an ionic antistatic agent.

The pressure-sensitive adhesive composition of the present invention improves the compatibility of the ionic antistatic agent by the ionic monomer immobilized by the polymerization reaction of the acrylic copolymer,

The bleed out phenomenon in which the antistatic agent component moves to the surface and precipitates is suppressed by the improvement of the compatibility, and the durability is excellent. This phenomenon can be suppressed even under high temperature or high temperature / humidity environment, thereby maintaining excellent durability.

In addition, in the pressure-sensitive adhesive composition of the present invention, since the ionic monomer has an antistatic property together with the ionic antistatic agent, its performance is significantly improved as compared with the pressure-sensitive adhesive composition using a conventional antistatic agent alone.

The ionic monomer contained in the acrylic copolymer includes a vinyl group so as to be copolymerizable with the acrylate monomer, and may be used to form an ionic bond with the ionic antistatic agent.

Specifically, the ionic monomer

or

Can be.

These ionic monomers can be prepared by commercially available products or by synthesis, for example the synthesis can be used the method of US Pat. No. 3,226,881.

It is preferable that the acryl-type copolymer of this invention contains the (meth) acrylate monomer which has a C1-C12 alkyl group, and the ionic monomer which has a vinyl group. In the present invention, (meth) acrylate means acrylate and methacrylate.

Examples of the (meth) acrylate monomer having an alkyl group having 1 to 12 carbon atoms include n-butyl (meth) acrylate, 2-butyl (meth) acrylate, t-butyl (meth) acrylate, and 2-ethylhexyl (meth). ) Acrylate, ethyl (meth) acrylate, methyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, pentyl (meth) acrylate, n-octyl (meth) acrylate Isooctyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, and the like, among which n-butyl acrylate and 2-ethylhexyl acrylate Or mixtures thereof. These can be used individually or in mixture of 2 or more types.

It is preferable that the said ionic monomer which has a vinyl group contains 0.1-10 weight part with respect to 100 weight part of (meth) acrylate monomers which have a C1-C12 alkyl group, More preferably, it is 0.5-5 weight part. If the content is less than 0.1 parts by weight, it may be difficult to secure durability due to insufficient compatibility improvement effect of the antistatic agent, and if it exceeds 10 parts by weight, it may be difficult to secure moisture and heat resistance due to excessively high hydrophilicity.

The acrylic copolymer of the present invention may further contain a polymerizable monomer having a crosslinkable functional group in addition to the ionic monomer having a vinyl group. The polymerizable monomer having a crosslinkable functional group uses a component that does not generate hydrogen ions (H ⁺ ), which can impart cohesion or adhesive strength of the pressure-sensitive adhesive composition by chemical bonding to impart durability and cutting properties.

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

As a monomer which has a hydroxyl group, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, 2-hydroxypropylene glycol (meth) acrylate, hydroxyalkylene glycol having 2 to 4 carbon atoms of an alkylene group ( Meta) acrylate, 4-hydroxybutyl vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, 7-hydroxyheptyl vinyl ether, 8-hydroxyoctyl vinyl ether, 9-hydroxynonyl Vinyl ether, 10-hydroxydecyl vinyl ether, etc. are mentioned, Among these, 4-hydroxybutyl vinyl ether is preferable.

Examples of the monomer having an amide group include (meth) acrylamide, N-isopropylacrylamide, N-tert-butylacrylamide, 3-hydroxypropyl (meth) acrylamide, 4-hydroxybutyl (meth) acrylamide, 6 -Hydroxyhexyl (meth) acrylamide, 8-hydroxyoctyl (meth) acrylamide, 2-hydroxyethylhexyl (meth) acrylamide, etc. are mentioned, Among these, (meth) acrylamide is preferable.

Monomers having a tertiary amine group include N, N- (dimethylamino) ethyl (meth) acrylate, N, N- (diethylamino) ethyl (meth) acrylate, and N, N- (dimethylamino) propyl ( Meth) acrylate, etc. are mentioned.

It is preferable that the polymerizable monomer which has such a crosslinkable functional group is contained in 0.05-10 weight part with respect to 100 weight part of (meth) acrylate monomers which have a C1-C12 alkyl group, More preferably, it is 0.1-8 weight part good. If the content is less than 0.05 parts by weight, the cohesive force of the pressure-sensitive adhesive may be reduced, the durability may be lowered. If the content is more than 10 parts by weight, the adhesive strength is lowered by a high gel fraction may cause problems in durability.

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

The production method of the copolymer is not particularly limited, and may be prepared using a method 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 the polymerization, may be used.

The acrylic copolymer preferably has a weight average molecular weight (polystyrene equivalent, Mw) measured by gel permeation chromatography (GPC) of 50,000 to 2 million, more preferably 400,000 to 2 million. If the weight average molecular weight is less than 50,000, there is a lack of cohesion between the copolymers may cause problems in adhesion durability, if the weight average molecular weight is more than 2 million may require a large amount of dilution solvent to ensure fairness during coating.

The ionic antistatic agent is not particularly limited as long as it is an ionic salt composed of an anion and a cation and can impart ionic conductivity to the pressure-sensitive adhesive.

Specifically, a cation selected from the group consisting of alkali metal salts, ammonium salts, sulfonium salts and phosphonium salts; It may be an ionic salt consisting of an anion selected from the group consisting of fluorine-containing inorganic salts, fluorine-containing organic salts and iodine ions.

Such an ionic antistatic agent may contain 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the acrylic copolymer. If the content is less than 0.1 parts by weight may be insufficient antistatic properties and if it exceeds 10 parts by weight it may be difficult to secure durability.

The pressure-sensitive adhesive composition of the present invention may further contain a crosslinking agent.

A crosslinking agent can improve adhesiveness and durability, and can maintain the reliability and shape of an adhesive at high temperature.

The crosslinking agent may be an isocyanate type, an epoxy type, a melamine type, a peroxide type, a metal chelate type, an oxazoline type, or the like, and one or two or more kinds thereof may be used. Double isocyanate type or epoxy type is preferred.

The isocyanate type is tolylene diisocyanate, xylene diisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tetramethyl xylene diisocyanate, naphthalenedi Diisocyanate compounds such as isocyanate; Diisocyanate obtained from 2 moles of an adduct obtained by reacting 3 moles of a diisocyanate compound with 1 mole of a polyhydric alcohol compound such as trimethylolpropane, an isocyanurate obtained by self-condensing 3 moles of the diisocyanate compound, and 3 moles of the diisocyanate compound And polyfunctional isocyanate compounds containing three functional groups such as biuret, triphenylmethanetriisocyanate, and methylenebistriisocyanate, in which the remaining 1 mole of diisocyanate is condensed to urea.

The epoxy-based ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol di Glycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polytetramethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, di Glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, resorcin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, trimethylolpropanetriglycidyl ether, pentaerythritol poly Glycidyl ether, sorbitol polyglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, tris (glycidyl) isocyanuric Tris (glycidoxyethyl) isocyanurate, 1,3-bis (N, N-glycidylaminomethyl) cyclohexane, N, N, N ', N'-tetraglycidyl-m- Xylylenediamine etc. are mentioned.

Examples of the melamine type include hexametholol melamine, hexamethoxymethyl melamine, hexabutoxymethyl melamine, and the like.

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 force may be reduced due to insufficient crosslinking degree, thereby impairing the adhesive durability and the cleavage property. If the content is more than 15 parts by weight, problems may occur in reducing residual stress due to excessive crosslinking reaction.

In addition to the above components, the pressure-sensitive adhesive composition is a silane coupling agent, tackifying resin, antioxidant, leveling agent, surface lubricant, dye, in order to adjust the adhesion, cohesion, viscosity, elastic modulus, glass transition temperature, etc. Additives, such as a pigment, an antifoamer, a filler, and a light stabilizer, can be further contained.

Such additives can be appropriately adjusted in a range not impairing the effects of the present invention.

In particular, the pressure-sensitive adhesive composition of the present invention can be used as a pressure-sensitive adhesive for polarizing plates and a surface protective film for bonding to liquid crystal cells. In addition, it can be used as a general commercial adhesive sheet product as well 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 adhesive for electronic parts, and the like.

Hereinafter, preferred examples are provided to aid the understanding of the present invention, but the following examples are merely for exemplifying the present invention, and it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention. It is natural that such variations and modifications fall within the scope of the appended claims.

Preparation Example: Acrylic Copolymer Preparation

Preparation Example 1

85 parts by weight of n-butyl acrylate (BA), 8 parts by weight of methyl acrylate (MA), 2-hydroxyethyl acrylate 2.0 in a 1 L reactor equipped with a refrigeration system to facilitate nitrogen temperature reflux and temperature control. Weight,

After adding a monomer mixture consisting of 5 parts by weight of an ionic monomer of 100 parts by weight of acetone as a solvent. Then, after purging nitrogen gas for 1 hour to remove oxygen, it was maintained at 62 ℃. After homogenizing the mixture, 0.07 parts 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 million.

Preparation Example 2

The same as in Preparation Example 1,

Instead of

An acrylic copolymer was prepared using.

Preparation Example 3

The same as in Preparation Example 1,

90 parts by weight of n-butyl acrylate (BA) was used to prepare an acrylic copolymer.

Preparation Example 4

In the same manner as in Preparation Example 1, 89.95 parts by weight of n-butyl acrylate (BA), 8 parts by weight of methyl acrylate (MA), 2.0 parts by weight of 2-hydroxyethyl acrylate,

An acrylic copolymer was prepared using a monomer mixture consisting of 0.05 parts by weight of an ionic monomer of.

Preparation Example 5

In the same manner as in Preparation Example 1, 89 parts by weight of n-butyl acrylate (BA), 8 parts by weight of methyl acrylate (MA), 2.0 parts by weight of 2-hydroxyethyl acrylate,

An acrylic copolymer was prepared using a monomer mixture consisting of 1 part by weight of an ionic monomer of.

Preparation Example 6

In the same manner as in Preparation Example 1, 81 parts by weight of n-butyl acrylate (BA), 8 parts by weight of methyl acrylate (MA), 2.0 parts by weight of 2-hydroxyethyl acrylate,

An acrylic copolymer was prepared using a monomer mixture consisting of 9 parts by weight of an ionic monomer of.

Preparation Example 7

In the same manner as in Preparation Example 1, 75 parts by weight of n-butyl acrylate (BA), 8 parts by weight of methyl acrylate (MA), 2.0 parts by weight of 2-hydroxyethyl acrylate,

An acrylic copolymer was prepared using a monomer mixture consisting of 15 parts by weight of an ionic monomer of.

Preparation Example 8

The same as in Preparation Example 1,

Instead, 5 parts by weight of acrylamide was used to prepare an acrylic copolymer.

Preparation Example 9

The same as in Preparation Example 1,

Instead, 5 parts by weight of methoxyethyl acrylate was used to prepare an acrylic copolymer.

Preparation Example 10

The same as in Preparation Example 1,

Instead, 5 parts by weight of acrylic acid was used to prepare an acrylic copolymer.

Example 1-8 and Comparative Example 1-4

As shown in Table 1, an acrylic copolymer, an ionic antistatic agent, a crosslinking agent (Japan urethane CORONATE-L, 0.5 parts) and a silane coupling agent (Shin-Etsu Co., Ltd. KBM-403, 0.5 parts) were mixed, and then diluted with ethyl acetate to solid content. A pressure-sensitive adhesive composition having a concentration of 15% was prepared. In this case, Table 1 describes the acrylic copolymer and the ionic antistatic agent, and other crosslinking agents and silane coupling agents used the same components and contents.

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

A pressure-sensitive adhesive polarizing plate was prepared by laminating the pressure-sensitive adhesive layer prepared above on an iodine-based polarizing plate having a thickness of 185 μm. The prepared polarizing plate was stored for 20 days under conditions of 23 degreeC and 60% RH.

TABLE 1

Test Example

The physical properties of the pressure-sensitive adhesive composition and pressure-sensitive adhesive polarizing plate prepared in Examples and Comparative Examples were measured by the following method, and the results are shown in Table 2 below.

1.Surface Resistivity (Ω / □)

The prepared pressure-sensitive adhesive polarizing plate was measured 10 times each of three points of the pressure-sensitive adhesive layer using a surface resistance measuring instrument (MCP-HT450, Mitsubishi Chemical Co., Ltd.), and the average value thereof was represented.

Thereafter, the pressure-sensitive adhesive polarizing plate was left at 60 ° C. for 24 hours and then measured in the same manner as above.

2. Heat resistance / humidity heat resistance

After peeling the release film of the polarizing plate with an adhesive and bonding the surface of an adhesive layer and Corning glass, after leaving for 300 hours at 80 degreeC (heat resistance) / 60 degreeC, 90 RH% (humidity heat resistance), the external appearance was confirmed.

<Evaluation Criteria>

Bubble and Peeling Admitted Admitted: ×

Bubble or peeling is slightly visible but polarizer performance is maintained: ○

Bubbles and Peelings Unidentified: ◎

3. Corrosion resistance of metal layer

After peeling the release film of the polarizing plate with an adhesive, after bonding the surface of an adhesive layer and an aluminum plate, it left for 250 hours in 60 degreeC and 95% RH atmosphere, and manufactured the specimen.

The adhesive layer was peeled from the said laminated body, the surface of the aluminum plate which contacted the said adhesive layer was visually observed, and the presence or absence of corrosion was evaluated.

<Evaluation Criteria>

The aluminum plate surface is not corroded at all: ◎

The surface of aluminum plate is slightly corroded, but the function of aluminum plate is maintained: ○

Surface of aluminum plate is corroded: ×

TABLE 2

As shown in Table 2, the pressure-sensitive adhesive composition of Examples 1 to 8 containing the acrylic copolymer containing the ionic monomer having a vinyl group and the ionic antistatic agent according to the present invention has a durability (heat resistance and Heat resistance), antistatic properties and corrosion resistance was confirmed to be excellent at the same time.

Claims (7)

1. Adhesive composition containing the acrylic copolymer containing the ionic monomer which has a vinyl group, and an ionic antistatic agent.
2. The method according to claim 1, wherein the ionic monomer having a vinyl group

   

   or

   

   Pressure-sensitive adhesive composition.
3. The pressure-sensitive adhesive composition of claim 1, wherein the acrylic copolymer contains a (meth) acrylate monomer having an alkyl group having 1 to 12 carbon atoms and an ionic monomer having a vinyl group.
4. The pressure-sensitive adhesive composition according to claim 3, wherein the ionic monomer having a vinyl group is contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of a (meth) acrylate monomer having an alkyl group having 1 to 12 carbon atoms.
5. The method according to claim 1, wherein the ionic antistatic agent is a cation selected from the group consisting of alkali metal salts, ammonium salts, sulfonium salts and phosphonium salts;

   Pressure-sensitive adhesive composition which is an ionic salt consisting of an anion selected from the group consisting of fluorine-containing inorganic salts, fluorine-containing organic salts and iodine ions.
6. The pressure-sensitive adhesive composition of claim 5, wherein the ionic antistatic agent contains 0.1 to 5 parts by weight with respect to 100 parts by weight of the acrylic copolymer.
7. The pressure-sensitive adhesive composition of claim 1, wherein the pressure-sensitive adhesive composition further contains a crosslinking agent.