TW201504266A - Acrylic copolymer and adhesive composition containing same - Google Patents

Abstract

Provided are an acrylic copolymer and an adhesive composition containing the same. The adhesive composition can shorten the curing period to improve productivity, inhibit the viscosity change to improve storage stability, and satisfy physical properties such as durability, high-heat resistance, and reworkability, by using an acrylic copolymer containing a compound of Chemical Formula 2 below: wherein, R1 is C1-C12 aliphatic hydrocarbon; and R2 and R3 are each independently hydrogen, C1-C12 aliphatic hydrocarbon, or C6-C12 aromatic hydrocarbon.

Description

Acrylic copolymer and adhesive composition comprising acrylic copolymer

The present invention relates to an adhesive composition which can shorten durability during curing and can improve durability without lowering liquid stability.

A liquid crystal display (LCD) having an LCD panel includes an LCD unit cell and a polarizing plate adhered to both sides of the LCD panel via an adhesive layer.

The adhesive is used to satisfy physical properties such as reworkability and durability such as adhesion to a substrate, prevention of light leakage, and heat resistance and moist heat resistance. In addition, an adhesive can be used to shorten one of the physical factors for improving productivity during curing.

Korean Patent Publication No. 10-2010-0113487 discloses an adhesive composition obtained by using an acrylamide monomer having a hydroxyl group as a crosslinking agent to shorten the physical properties of a conventional adhesive while curing. .

However, although the conventional adhesive composition has the advantage of a short curing period, its reactivity in a liquid increases, resulting in deterioration of liquid stability. In addition, since the current stress tends to make the polarizer protective film thin and weak, and the stress caused by the high stretching of the polarizer is increased, the heat resistance of the polarizing plate is deteriorated, so that the conventional adhesive cannot effectively improve the heat resistance of the polarizing plate. The problem of poor sex.

Accordingly, the present invention solves the above-mentioned problems occurring in the prior art, and it is an object of the present invention to provide an adhesive composition which can improve liquid stability and shorten curing during curing without adding a crosslinking accelerator, and is sufficient for high Heat resistance, which is an essential property of the adhesive composition of the current polarizing plate.

To achieve this goal, an acrylic copolymer is provided herein comprising a compound of formula 1:

Wherein R ₁ is a C ₁ -C ₁₂ aliphatic hydrocarbon; and R ₂ and R ₃ are each a single hydrogen, a C ₁ -C ₁₂ aliphatic hydrocarbon, or a C ₆ -C ₁₂ aromatic hydrocarbon.

Here, in the compound of Chemical Formula 1, R ₁ may be a C ₁ -C ₄ alkyl group; and R ₂ and R ₃ may each be a single hydrogen, a C ₁ -C ₄ alkyl group, or a C ₆ -C ₈ benzene group. Base or benzyl.

The compound of Chemical Formula 1 may be at least one selected from the group consisting of compounds of Chemical Formulas 2 to 5:

[Chemical Formula 4]

The acrylic copolymer may include a (meth) acrylate monomer having an alkyl group of 4 to 12 carbon atoms and a compound of Chemical Formula 1.

The compound of Chemical Formula 1 may be contained in an amount of 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.

According to another object of the present invention, there is provided an adhesive composition comprising the acrylic copolymer.

The adhesive composition may further comprise a crosslinking agent.

The present invention discloses an adhesive composition which can shorten durability during curing and can improve durability without lowering liquid stability.

Next, the details of the present invention will be described below.

An acrylic copolymer of the present invention comprising the compound of the following Chemical Formula 1: [Chemical Formula 1]

Wherein, Rl is C ₁ -C ₁₂ aliphatic hydrocarbon; and R ₂ and R ₃ are individually hydrogen, C ₁ -C ₁₂ aliphatic hydrocarbon, or C ₆ -C ₁₂ aromatics.

Preferably, in the compound of Chemical Formula 1, R1 may be a C ₁ -C ₄ alkyl group; and each of R ₂ and R ₃ may be a single hydrogen, a C ₁ -C ₄ alkyl group, or a C ₆ -C ₈ benzene group. Base or benzyl.

Most preferably, the compound of Chemical Formula 1 may be at least one selected from the group consisting of the following Chemical Formulas 2 to 5:

The acrylic copolymer of the present invention preferably comprises a (meth) acrylate monomer having an alkyl group of 4 to 12 carbon atoms and the compound of the above Chemical Formula 1. Here, the term "(meth)acrylate" means acrylate and methacrylate.

The compound of Chemical Formula 1 contains a monofunctional group for crosslinking in a molecule In the case of a combined reaction, it plays the role of a basic catalyst and an active group.

More specifically, an amide group and a monohydroxy group are contained in the molecule of the compound of Chemical Formula 1. The acrylic copolymer including the compound accelerates the crosslinking reaction between the crosslinking agent and the crosslinkable monomer to shorten the curing period of the adhesive.

Further, although the compound of Chemical Formula 1 contains an amide group as a catalyst and a hydroxyl group to carry out a crosslinking reaction with an amide group in its molecule, liquid decomposition in a solvent can be ensured by solvation into an amide group and a hydroxyl group.

Further, after the completion of the curing, the structure of the compound is formed by cross-linking between the main chains to form a cross-linked structure instead of the cross-linking agent formed by the side chain, resulting in an increase in cross-linking density, thereby improving heat resistance. .

The alkyl (meth) acrylate monomer having 4 to 12 carbon atoms is a (meth) acrylate derived from a fatty alcohol having 4 to 12 carbon atoms, and an example thereof is n-(meth)acrylic acid butyl. Ester, butyl 2-(meth)acrylate, butyl t-(meth)acrylate, amyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth) acrylate, Ethyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, and the like. They may be used singly or in combination of two or more. Among them, preferred is n-(meth)acrylate butyl ester, 2-ethylhexyl (meth) acrylate, or a mixture thereof.

The compound of Chemical Formula 1 may be contained in an amount of 0.1 to 10 parts by weight, and preferably 0.5 to 3 parts by weight based on 100 parts by weight of the (meth) acrylate monomer having an alkyl group having 1 to 12 carbon atoms. Share. If the content of the compound is less than 0.1 parts by weight, the acceleration effect of the crosslinking reaction will be poor, and the degree of crosslinking will be lowered to shorten the curing. Improve durability during the period. When the content of the compound exceeds 10 parts by weight, the crosslinking reaction becomes fast, the liquid stability is deteriorated, and the cohesive force is deteriorated due to excessive cohesion, resulting in peeling defects under heat-resistant conditions.

Further, the acrylic copolymer of the present invention may further comprise a polymerizable monomer having a crosslinkable functional group in addition to the crosslinkable functional group of the compound of Chemical Formula 1. The polymerizable monomer can provide cohesive force or adhesion through chemical bonding with the following crosslinking agent. Examples thereof may include a monomer having a monohydroxy group, a monomer having a monocarboxy group, a monomer having a monoamide group, a monomer having a tertiary amino group, and the like. They may be used singly or in combination of two or more.

Examples of the monomer having a hydroxyl group are hydroxyethyl 2-(meth)acrylate, hydroxypropyl 2-(meth)acrylate, hydroxybutyl 2-(meth)acrylate, 4-hydroxybutyl (methyl) Acrylate, 6-hydroxyhexyl (meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate, 2-hydroxy propylene glycol (meth) acrylate, having 2 to 4 carbon atoms Alkylene hydroxyalkylene glycol (meth) acrylate, 4-hydroxybutyl vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, 7-hydroxyheptyl ethylene Ethyl ether, 8-hydroxyoctyl vinyl ether, 9-hydroxydecyl vinyl ether, 10-hydroxydecyl vinyl ether, and the like. Among them, 4-hydroxybutyl vinyl ether is preferred.

Examples of the monomer having a monocarboxy group are a monovalent acid such as (meth) acrylate, crotonic acid, and the like; a divalent acid such as maleic acid, itaconic acid, fumaric acid, and the like, and a monoalkylene thereof a succinic anhydride ring-opening adduct of 2-(meth)acryloylpropionic acid; 2-hydroxyalkyl (meth) acrylate having an alkyl group of 2 to 3 carbon atoms, having 2 to 4 Carbonic acid alkylene hydroxyalkylene glycol (meth) acrylate succinic acid An open-loop anhydride adduct, and a compound obtained by a caprolactone adduct of a 2-hydroxyalkyl (meth) acrylate having a succinic anhydride ring-opening adduct and an alkyl group having 2 to 3 carbon atoms. ; and the like. Among them, (meth) acrylate is preferred.

Examples of the monomer having an amide group are (meth)acrylamide, hydroxyethyl acrylamide, N-isopropylacrylamide, N-tert-butylacrylamide, 3-hydroxypropyl (meth)acrylamide, 4-hydroxybutyl (meth) acrylamide, 6-hydroxyhexyl (meth) acrylamide, 8-hydroxyoctyl (meth) acrylamide, 2-hydroxyhexyl (meth) acrylamide, and the like. Among them, (meth)acrylamide is preferred.

Examples of the monomer having a tertiary amino group are N,N-(dimethylamino)ethyl (meth) acrylate, N,N-(diethylamino)ethyl (meth) acrylate, N, N-(dimethylamino)propyl (meth) acrylate, and the like.

The content of the polymerizable monomer having a crosslinkable functional group is preferably from 0.1 to 10 parts by weight, and most preferably from 0.5 to 3, based on 100 parts by weight of all monomers for preparing the acrylic copolymer. Parts by weight. If it is less than 0.1 part by weight, the cohesive force of the adhesive will be reduced, resulting in deterioration of durability. If it exceeds 10 parts by weight, the adhesive force of the adhesive will be lowered due to a high gel fraction and cause a problem of durability.

Furthermore, other polymerizable monomers than the above monomers may be further included without reducing the adhesive force of the adhesive, for example, 100 weights of all monomers used for preparing the acrylic copolymer. On the basis of the basis, the content is not more than 40 parts by weight.

Among these polymerizable monomers, an aromatic monomer having a high glass transition temperature (Tg) to increase the glass transition temperature or an aromatic monomer for preventing light leakage.

The preparation method of the copolymer is not particularly limited. The copolymer can be prepared by conventional methods such as bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization. Among them, solution polymerization is preferred. Further, a solvent commonly used in conventional polymerization, a polymerization initiator, a chain transfer agent for controlling molecular weight, and the like can also be used.

The weight average molecular weight of the copolymer (in terms of polystyrene, Mw), measured by colloidal permeation chromatography, is from 50,000 to 2,000,000, and preferably from 400,000 to 2,000,000. If the weight average molecular weight of the copolymer is less than 50,000, the adhesion between the copolymers will be insufficient, resulting in a problem of adhesion durability. If the weight average molecular weight of the copolymer exceeds 200,000, a large amount of a diluent solvent is required to ensure processability at the time of coating.

Further, the present invention is characterized in that the adhesive composition comprises an acrylic copolymer. The adhesive composition may further comprise a crosslinking agent.

The crosslinking agent is a composition for appropriately crosslinking the copolymer to increase the cohesive force of the adhesive, and the kind of the crosslinking agent is not particularly limited. Examples of the crosslinking agent include an isocyanate compound, an epoxy resin compound, and the like, and these may be used singly or in combination of two or more.

Examples of the isocyanate compound are diisocyanate compounds such as toluene diisocyanate, xylene diisocyanate, 2,4-diphenylmethane diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, and the like. a ketone diisocyanate, tetramethyl xylene diisocyanate, and naphthalene diisocyanate; a reaction obtained by reacting a 3 mol diisocyanate compound with a 1 mol polyol compound such as trimethylolpropane a product, with 3 moles of diisocyanate compound An isocyanurate body obtained by self-condensation, a condensation obtained by condensing a diisocyanate urea obtained from a 2 molar diisocyanate compound in 3 moles with the remaining 1 molar diisocyanate compound a urea body, and a polyfunctional isocyanate compound having three functional groups such as triphenylmethane triisocyanate and methylene diisocyanate; and the like.

Examples of the epoxy resin compound are ethylene glycol diglycidyl ether, diethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol II. Glycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, polybutylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, glycerin Polydiether, polyglycerol polyglycidyl ether, resorcinol diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol polyglycidyl Ether, sorbitol polyglycidyl ether, diglycidyl adipate, diglycidyl phthalate, tris(glycidyl)isocyanurate, tris(glycidoxyethyl) Cyanurate, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylylenediamine, and such as.

Further, as for the crosslinking agent, the melamine-based compound may be used singly or in combination of two or more kinds of an isocyanate-based compound and an epoxy resin-based compound.

Examples of the melamine-based compound are hexamethylol melamine, hexamethoxymethyl melamine, hexabutoxymethyl melamine, and the like.

The content of the crosslinking agent is preferably from 0.1 to 5 parts by weight and most preferably from 0.1 to 2 parts by weight, based on 100 parts by weight of the copolymer. Crosslinking When the content of the agent is less than 0.1 part by weight, the cohesive force may be lowered due to insufficient crosslinking degree, resulting in deterioration of durability such as air bubbles, and cuttability may be deteriorated. If the content of the crosslinking agent exceeds 5 parts by weight, the adhesion may be deteriorated due to excessive crosslinking reaction, resulting in defects in durability such as peeling.

Further, the adhesive composition of the present invention may further comprise a decane coupling agent.

The kind of the decane coupling agent is not particularly limited. Examples of the decane coupling agent are vinyl chlorodecane, vinyl trimethoxy decane, vinyl triethoxy decane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxy decane, 3-ring Oxypropoxypropyltrimethoxydecane, 3-glycidoxypropylmethyldiethoxydecane, 3-glycidoxypropylmethyldiethoxydecane, 3-epoxypropane Oxypropyl triethoxy decane, p-styryl trimethoxy decane, 3-methacryloxypropyl triethoxy decane, 3-methacryloxypropyl trimethoxy decane, 3-methacryloyloxymethyldimethoxydecane, 3-methacryloxypropylmethyldiethoxydecane, 3-acryloxypropyltrimethoxydecane, N-2 -(aminoethyl)-3-aminopropylmethyldimethoxydecane, N-2-(aminoethyl)-3-aminopropyltrimethoxydecane, N-2-(aminoethyl)- 3-aminopropyltriethoxydecane, 3-aminopropyltrimethoxydecane, 3-aminopropyltriethoxydecane, 3-triethoxymethylidene-N-(1,3-di Methyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxydecane, 3-chloropropyltrimethoxy Decane, 3-mercaptopropylmethyldimethoxydecane, 3-mercaptopropyltrimethoxydecane, bis(triethoxymethanepropylpropyl)tetrasulfide, 3-isocyanatepropyltriethoxydecane , and the like. They may be used singly or in combination of two or more.

The content of the decane coupling agent is preferably from 0 to 10 parts by weight and most preferably from 0.005 to 5 parts by weight, based on 100 parts by weight of the copolymer. When the content of the decane coupling agent exceeds 10 parts by weight, the durability is deteriorated.

The adhesive composition may further comprise, in addition to the above composition, such as a tackifier resin, an antioxidant, a corrosion inhibitor, a leveling agent, a surface lubricant, a dye, a pigment, an antifoaming agent, a filler, a light stabilizer, and an antistatic agent. Additives to adjust the adhesive, cohesiveness, viscosity, modulus of elasticity, glass transition temperature, antistatic properties, and the like required for the adhesive composition.

The adhesive composition of the present invention can be used as an adhesive for bonding a polarizing plate to a liquid crystal cell or an adhesive for a surface protective film. Further, the adhesive composition of the present invention can be used for a protective film, a reflective sheet, an adhesive sheet for molding, an adhesive sheet for photography, an adhesive sheet for marking a land, an optical adhesive product, and an electronic product. Adhesives for products, as well as patches for medical applications and patches for medical use.

The preferred embodiments are provided to aid in the understanding of the present invention, and the following examples are merely illustrative of the invention and are not intended to limit the invention. The scope of the present invention is defined by the scope of the appended claims, unless otherwise claimed.

Example 1: Preparation of Acrylic Copolymer Example 1-1

89.5 parts by weight of n-butyl acrylate (BA), 10 parts by weight of propylene A monomer mixture of methyl ester (MA) and 2 parts by weight of a compound of formula 2 is placed in a 1 liter reactor with a cooling device to promote nitrogen reflux and temperature control, and then 100 parts by weight of acetic acid. Ethyl ester (acetone) was added as a solvent. After that, it was purged with nitrogen for 1 hour to remove oxygen, and the temperature was maintained at 62 °C. Stir the monomer mixture evenly. Then, 0.07 part by weight of azobisisobutyronitrile (AIBN) was further added as a reaction initiator, followed by a reaction for 8 hours to prepare an acrylic copolymer having a weight average molecular weight of about 1,000,000.

Examples 1-1 to 1-10 and Comparative Examples 1 to 4

The acrylic copolymer was prepared by the same method as in Preparation Example 1, and the combination shown in Table 1 below was used.

Examples 2-1 to 2-13 and Comparative Examples 5 to 9

The adhesive composition was prepared by mixing the composition of the composition as shown in Table 2 below, followed by dilution with ethyl acetate. Each of the adhesive compositions prepared as above was applied onto a release film coated with a ruthenium release agent to have a thickness of 25 μm, followed by drying at 100 ° C for 1 minute to form an adhesive layer.

The formed adhesive layer was adhered to a 185 μm thick iodine-based polarizing plate by an adhesive treatment to produce an adhesive polarizing plate.

Test case

The characteristics of the adhesive composition, the adhesive sheet, and the adhesive-attached polarizing plate obtained by the examples and the comparative examples were measured by the following methods, and the measurement results are recorded in Table 3.

1. Storage stability (viscosity change, %)

The viscosity of the adhesive composition was measured using a viscometer (Brookfield LVDV-II+B type (rotor code 3, 30 rpm)) and the viscosity of the adhesive composition after standing at room temperature for 24 hours, and the viscosity was calculated. Change (Δη).

<Evaluation criteria>

○: Δη <10%

Δ: 10% Δη<20%

×: 20% Δη

2. During curing

When the prepared adhesive sheet was cured at 23 ° C and 65% RH for 1 to 10 days, the gel fraction was measured daily as described below. The number of days of curing is extended until the gel fraction is no longer increased, that is, the curing period is determined accordingly.

Approximately 0.25 g of the adhesive layer of the adhesive sheet was fixed to a 250-mesh wire mesh (100 mm X 100 mm), and the wire mesh was wrapped to prevent the gel from escaping therefrom. A precision balance was used to accurately measure the weight, and the wire mesh was immersed in an ethyl acetate solution for 3 days. Remove the soaked wire mesh, followed by a small amount The ethyl acetate solution was rinsed, dried at 120 ° C for 24 hours, and then weighed. The measured weight is used to calculate the gel fraction by Equation 1. The gelation rate (%) = (CA) / was determined based on the calculated time when the gel fraction fell within the range of 70% to 80% and no change with time was observed: [Equation 1] (BA) X 100

[In Equation 1, A is the weight (g) of the wire mesh; B is the weight of the adhesive layer fixed to the wire mesh (BA: weight of the adhesive layer, g); and C is the wire mesh after soaking and drying Weight (CA: weight of gel resin, g)].

3. Durability (heat resistance, heat and humidity resistance)

The prepared polarizing plate with an adhesive was cut into a size of 90 mm × 170 mm to prepare a sample, and the release film was peeled off therefrom, and the polarizing plate was attached to both sides of the glass substrate (110 mm × 190 mm × 0.7 mm). The light absorption axes of the polarizing plates are made orthogonal to each other. Here, a pressure of 5 kg/cm ² was applied and carried out in a clean room to avoid generation of bubbles or foreign materials. In order to measure heat resistance, the sample was placed at a temperature of 80 ° C for 1000 hours, and then, whether or not foaming or peeling occurred was observed. In order to measure the heat and humidity resistance, the sample was placed under conditions of 60 ° C and 90% RH for 1000 hours, and it was observed whether foaming or peeling occurred. Here, the sample was placed at room temperature for 24 hours before the sample evaluation.

<Evaluation criteria>

◎: No bubbles or peeling:

○: The number of bubbles or peeling <5

Δ: 5 The number of bubbles or peeling <10

×:10 Number of bubbles or strips

4. Reworkability

The polarizing plate to which the adhesive was produced was cut into 25 mm × 100 mm, and then the release film was peeled off. The polarizing plate was laminated to a glass substrate (Corning #1737, Corning) by applying a pressure of 0.25 MPa, and subjected to high pressure treatment at 5 atm and 50 ° C for 20 minutes to prepare an evaluation sample. In order to measure the heat-resistant reworkability, the sample was stored in an oven at 80 ° C for 10 hours and then taken out. Then, the sample was allowed to stand at room temperature for 120 hours, and the adhesive layer was peeled off at a rate of 1.3 cm/s. In order to measure the resistance to wet heat rework, the samples were stored in an oven at 60 ° C and 90 RH% for 12 hours and then taken out. Then, the sample was allowed to stand at room temperature for 120 hours, and the adhesive layer was peeled off at a rate of 1.3 cm/s. The heat resistance reworkability and the heat and humidity rework resistance were evaluated based on the following criteria.

<Evaluation criteria>

○: In the case of heat-resistant reworkability and wet heat-resistant reworkability, no adhesive remained on the glass substrate and the adhesive layer was completely peeled off without tearing the polarizing plate.

Δ: In the case of heat-resistant reworkability or wet heat-resistant reworkability, a small amount of the adhesive remains on the glass substrate and the adhesive layer is completely peeled off without tearing the polarizing plate.

X: In the case of any of heat-resistant reworkability and wet heat-resistant reworkability, a large amount of the adhesive remains on the glass substrate, and the polarizing plate is torn when the adhesive layer is peeled off.

[table 3]

As is apparent from Table 3, the adhesive compositions of Examples 2-1 to 2-13 including the compound of Chemical Formula 1 according to the present invention have better liquid stability and shorter than the adhesive compositions of Comparative Examples 5 to 9. Hardening period, durability (heat resistance and heat and humidity resistance), and reworkability.

As described above, the adhesive composition of the present invention can improve liquid stability and shorten the curing period without the addition of a crosslinking accelerator, and has a satisfactory high heat resistance, which is an adhesive composition of the current polarizing plate. Required features.

Claims (7)

An acrylic copolymer comprising a compound of Chemical Formula 1: Wherein R ₁ is a C ₁ -C ₁₂ aliphatic hydrocarbon; and R ₂ and R ₃ are each a single hydrogen, a C ₁ -C ₁₂ aliphatic hydrocarbon, or a C ₆ -C ₁₂ aromatic hydrocarbon. The acrylic copolymer according to claim 1, wherein in the compound of Chemical Formula 1, R ₁ is a C ₁ -C ₄ alkyl group; and R ₂ and R ₃ are each independently hydrogen, C ₁ -C ₄ Alkyl, or C ₆ -C ₈ phenyl or benzyl. The acrylic copolymer according to claim 2, wherein the compound of Chemical Formula 1 is at least one selected from the group consisting of compounds of Chemical Formulas 2 to 5: The acrylic copolymer according to claim 1, wherein the acrylic copolymer comprises a (meth) acrylate monomer having an alkyl group of 4 to 12 carbon atoms and a compound of Chemical Formula 1. The acrylic copolymer according to claim 4, wherein the content of the compound of Chemical Formula 1 is 100 parts by weight based on 100 parts by weight of the alkyl (meth) acrylate monomer having 1 to 12 carbon atoms. It is 0.1 to 10 parts by weight. An adhesive composition comprising the acrylic copolymer of any one of claims 1 to 5. The adhesive composition of claim 6, further comprising a crosslinking agent.