KR102427986B1 - Acryl-based adhesive composition, polarizing plate and display device - Google Patents

Abstract

The present invention, an acrylic copolymer comprising an acrylic copolymer formed by polymerizing a monomer mixture comprising a monomer represented by the following [Formula 1], an alkyl (meth) acrylate monomer, and a (meth) acrylic monomer having a crosslinkable functional group An adhesive composition, wherein the acrylic copolymer has a weight average molecular weight of 500,000 to 1,000,000 and a polymerization conversion rate of 70% or less.
[Formula 1]
R ¹ -CH=CR ² -(C=O)-OXY
In Formula 1, R ¹ is hydrogen, a C1 to C6 alkyl group or a C1 to C6 alkenyl group, R ² is hydrogen or a C1 to C10 alkyl group, X is a single bond, a C1 to C10 alkylene group, a C2 to C10 alkenylene group , ether, ester, or a combination thereof, and Y is a vinyl group, an allyl group, or a C3-C10 cycloalkenyl group.

Description

Acrylic pressure-sensitive adhesive composition, polarizing plate, and display device {ACRYL-BASED ADHESIVE COMPOSITION, POLARIZING PLATE AND DISPLAY DEVICE}

The present invention relates to an acrylic pressure-sensitive adhesive composition, a polarizing plate, and a display device, and more particularly, to an acrylic pressure-sensitive adhesive composition having excellent durability and little change over time after forming an adhesive layer, and a polarizing plate and display device manufactured using the same.

In general, a liquid crystal display device (LCD) includes a liquid crystal cell containing liquid crystal and a polarizing plate, and an adhesive layer is used to attach the liquid crystal cell and the polarizing plate. Acrylic resins, rubbers, urethane resins, silicone resins, or EVA (Ethylene Vinyl Acetate) are used as adhesives for attaching polarizing plates that form the adhesive layer. Among them, acrylic resins with transparency, oxidation resistance and yellowing resistance are used as the base. Adhesives are widely used.

In the case of the acrylic pressure-sensitive adhesive for a polarizing plate, it is preferable to use an acrylic resin having a high weight average molecular weight in order to improve durability and curing efficiency. This is because, when an acrylic resin having a low weight average molecular weight is used, curing efficiency is lowered and the curing rate is slowed, and the cohesive force and curing degree of the pressure-sensitive adhesive are lowered under high temperature or high temperature/high humidity conditions, thereby reducing durability. However, when an acrylic resin having a high weight average molecular weight is used, there is a problem in that the viscosity of the coating solution increases and workability decreases. The viscosity of the coating solution can be adjusted by lowering the solid content in the coating solution. However, when the adhesive layer is formed using a coating solution with a low solid content as described above, the manufacturing cost increases and productivity decreases, and it is difficult to precisely control the thickness of the adhesive layer. There is a problem.

In order to solve this problem, conventionally, an acrylic resin having a low weight average molecular weight exhibiting relatively low viscosity characteristics is used, but a monomer having a crosslinkable functional group such as a hydroxyl group or a carboxy group is added to prepare an acrylic resin, and the acrylic resin is prepared. A method of improving the durability of the adhesive layer by forming a crosslinked structure between polymer chains through a reaction between the curing agent and a crosslinkable functional group during coating by mixing a curing agent with a resin has been proposed. However, in the case of such a conventional method, the crosslinking reaction proceeds slowly by the curing agent remaining even after the formation of the adhesive layer is completed, and the peeling force of the adhesive layer is lowered over time by this additional crosslinking reaction, Due to this, problems such as a decrease in durability of the polarizing plate occur.

Therefore, there is a demand for the development of an acrylic pressure-sensitive adhesive composition that has little change over time after forming the pressure-sensitive adhesive layer and can realize excellent durability.

An object of the present invention is to solve the above problems, and to provide an acrylic pressure-sensitive adhesive composition that has little change over time after forming an adhesive layer and can realize excellent durability.

In addition, the present invention is to provide a polarizing plate including a pressure-sensitive adhesive layer formed by the acrylic pressure-sensitive adhesive composition as described above and a display device including the same.

In one aspect, the present invention, an acrylic copolymer formed by polymerizing a monomer mixture comprising a monomer represented by the following [Formula 1], an alkyl (meth) acrylate monomer, and a (meth) acrylic monomer having a crosslinkable functional group An acrylic pressure-sensitive adhesive composition comprising a, wherein the acrylic copolymer has a weight average molecular weight of 500,000 to 1,000,000, and provides an acrylic pressure-sensitive adhesive composition having a polymerization conversion of 70% or less.

[Formula 1]

R ¹ -CH=CR ² -(C=O)-OXY

In Formula 1, R ¹ is hydrogen, a C1 to C6 alkyl group or a C1 to C6 alkenyl group, R ² is hydrogen or a C1 to C10 alkyl group, X is a single bond, a C1 to C10 alkylene group, a C2 to C10 alkenylene group , ether, ester, or a combination thereof, and Y is a vinyl group, an allyl group, or a C3-C10 cycloalkenyl group.

In another aspect, the present invention provides a polarizing film; and an adhesive layer formed on one or both sides of the polarizing film and comprising a cured product of the acrylic pressure-sensitive adhesive composition according to the present invention.

In another aspect, the present invention provides a display device including the polarizing plate according to the present invention.

The acrylic pressure-sensitive adhesive composition according to the present invention uses an acrylic copolymer having a low polymerization conversion rate and uses an unsaturated hydrocarbon functional group remaining in the copolymer to allow an additional crosslinking reaction to proceed when forming an adhesive layer, thereby significantly reducing the amount of curing agent used compared to the prior art. In this way, it is possible to effectively suppress the occurrence of changes over time in the adhesive layer due to the unreacted curing agent.

In addition, the acrylic pressure-sensitive adhesive composition according to the present invention, including the acrylic copolymer having a branched polymer structure, can implement a low viscosity despite using the acrylic copolymer having a relatively high weight average molecular weight.

In addition, when the acrylic pressure-sensitive adhesive composition according to the present invention is used, low viscosity can be realized even when the solid content in the coating solution is high as 30% by weight or more, so that the coating workability is excellent when forming the pressure-sensitive adhesive layer, and the productivity is high. , it is possible to precisely control the thickness of the adhesive layer.

In addition, the polarizing plate including the pressure-sensitive adhesive layer formed using the acrylic pressure-sensitive adhesive composition according to the present invention has very low change over time of the pressure-sensitive adhesive layer, and has excellent durability even under high temperature and high temperature/high humidity conditions.

Hereinafter, the present invention will be described in detail.

When 'including', 'having', 'consisting', etc. mentioned in this specification are used, other parts may be added unless 'only' is used. When a component is expressed in the singular, the case in which the plural is included is included unless specifically stated otherwise.

In interpreting the components, it is interpreted as including an error range even if there is no separate explicit description.

In this specification, "(meth)acryl" is a generic term for acryl and methacryl. For example, (meth)acrylate includes methacrylate and acrylate, and (meth)acrylic acid includes acrylic acid and methacrylic acid.

In this specification, "X to Y" which shows a range means "X or more and Y or less".

As used herein, "branched polymer structure" refers to a polymer structure having two or more long chains grown in different directions.

adhesive composition

First, the acrylic pressure-sensitive adhesive composition according to the present invention will be described.

(1) acrylic copolymer

The acrylic pressure-sensitive adhesive composition according to the present invention is formed by polymerizing a monomer mixture comprising a monomer represented by the following [Formula 1], an alkyl (meth)acrylate monomer, and a (meth)acrylic monomer having a crosslinkable functional group. include synthesis.

[Formula 1]

R ¹ -CH=CR ² -(C=O)-OXY

In Formula 1, R ¹ is hydrogen, a C1 to C6 alkyl group or a C1 to C6 alkenyl group, R ² is hydrogen or a C1 to C10 alkyl group, X is a single bond, a C1 to C10 alkylene group, a C2 to C10 alkenylene group , ether, ester, or a combination thereof, and Y is a vinyl group, an allyl group, or a C3-C10 cycloalkenyl group.

The monomer represented by [Formula 1] forms a crosslinked structure in the adhesive layer forming process and is for forming a branched polymer, for example, allyl methacrylate, allyl acrylate ), methallyl methacrylate, methallyl acrylate, 3-butenyl acrylate, but-3-enyl-2-methylprop-2-enoate (but-3-enyl-2-methylprop-2-enoate), 2-allyloxyethyl acrylate, 2-allyloxyethyl methacrylate, 3-allyloxypropyl 3-allyloxypropyl methacrylate, 3-allyloxypropyl acrylate, 2-allyloxyethoxyethyl methacrylate, 2-allyloxyethoxyethyl acrylate , cyclohex-2-enyl acrylate, cyclo-hex-2-en-1-yl-2-methylprop-2-enoate (cyclohex-2-en-1-yl) 2-methylprop-2-enoate) and 3-vinylcyclohex-2-enyl acrylate (3-vinylcyclohex-2-enyl acrylate) may be at least one selected from the group consisting of, but is not limited thereto.

Conventionally, acrylic copolymers having a linear polymer structure in which monomers are polymerized in one long chain form have been mainly used as acrylic copolymers used in pressure-sensitive adhesives for polarizing plates. However, when acrylic copolymers having such a linear structure are used, as the weight average molecular weight increases, the viscosity also increases, and thus there is a problem in that workability is deteriorated.

However, since the monomer of [Formula 1] has two or more ethylene groups, radical formation is possible in free radical polymerization, and thus chains can grow in different directions, so two or more chains having different growth directions A branched polymer having a Since the acrylic copolymer having such a branched polymer structure has a lower viscosity than the acrylic copolymer having a linear polymer structure having the same weight average molecular weight, excellent coating properties can be realized even when the solid content in the coating solution is increased.

In addition, some of the unsaturated hydrocarbon groups contained in the monomer represented by the [Formula 1] do not react in the polymerization process and remain in the copolymer, and then react with heat in the adhesion layer forming process (coating process) to form a crosslinked structure will form Therefore, when the monomer represented by [Formula 1] is included as described above, there is no need to include an excessive amount of a curing agent for forming an internal cross-linked structure of the pressure-sensitive adhesive composition.

The monomer represented by [Formula 1] may be included in an amount of 1 to 15 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the monomer mixture. When the content of the monomer represented by [Formula 1] is less than 1 part by weight, sufficient crosslinking does not proceed in the coating process for forming the adhesive layer, so that desired physical properties cannot be obtained. It cannot be used as an adhesive.

On the other hand, the alkyl (meth) acrylate-based monomer preferably includes an alkyl group having 2 to 14 carbon atoms. This is because, when the alkyl group included in the alkyl (meth) acrylate monomer is too long, the cohesive force of the pressure-sensitive adhesive is lowered, and it may be difficult to control the glass transition temperature (Tg) or the adhesiveness. For example, examples of the alkyl (meth) acrylate-based monomer include ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth)acrylate, sec-butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, n-octyl (meth)acrylate ) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate and tetradecyl (meth) acrylate, and in the present invention, one or a mixture of two or more of the above can be used

The alkyl (meth)acrylate-based monomer may be included in an amount of 84 parts by weight to 98.9 parts by weight, preferably 89.5 to 98.9 parts by weight, based on 100 parts by weight of the monomer mixture. When the content of the alkyl (meth) acrylate-based monomer satisfies the above range, excellent adhesion and durability may be obtained.

Next, the (meth)acrylic monomer having the crosslinkable functional group is for improving the adhesion between the pressure-sensitive adhesive and the substrate. Conventionally, it has been common to use a (meth)acrylic monomer having a crosslinkable functional group in order to improve cohesive force for elasticity of the pressure-sensitive adhesive, but the acrylic copolymer of the present invention can exhibit sufficient cohesive force without adding a crosslinkable functional group. . Therefore, in the present invention, a (meth)acrylic monomer having a small amount of crosslinkable functional group is used for the purpose of improving the adhesion between the pressure-sensitive adhesive and the substrate.

As the (meth)acrylic monomer having the crosslinkable functional group, for example, a hydroxyl group-containing monomer, a carboxyl group-containing monomer, or a nitrogen-containing monomer may be used, but is not limited thereto. Specific examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate ) acrylate, 8-hydroxyoctyl (meth)acrylate, 2-hydroxyethylene glycol (meth)acrylate or 2-hydroxypropylene glycol (meth)acrylate, and examples of the carboxyl group-containing monomer include is (meth)acrylic acid, 2-(meth)acryloyloxy acetic acid, 3-(meth)acryloyloxy propyl acid, 4-(meth)acryloyloxy butyric acid, acrylic acid duplex, itaconic acid, maleic acid and maleic anhydride. Examples of the nitrogen-containing monomer include (meth)acrylamide, N-vinyl pyrrolidone, or N-vinyl caprolactam, but are not limited thereto.

The (meth)acrylic monomer having the crosslinkable functional group may be included in an amount of 0.01 to 1 part by weight, preferably 0.01 to 0.5 part by weight, based on 100 parts by weight of the monomer mixture. When the content of the (meth)acrylic monomer having a crosslinkable functional group satisfies the above range, the adhesion to the substrate is excellent.

According to one embodiment, the (meth)acrylic copolymer is, based on 100 parts by weight of the monomer mixture, 84 parts by weight to 98.9 parts by weight of an alkyl (meth)acrylate-based monomer, 0.01 to 1 part by weight of a crosslinkable functional group ( It may be formed by polymerizing a monomer mixture comprising a meth)acrylic monomer and 1 to 15 parts by weight of a monomer represented by [Formula 1].

The acrylic copolymer according to the present invention may be prepared by mixing each of the above-described monomers to prepare a monomer mixture, and then polymerizing the same. At this time, the polymerization reaction is terminated when the polymerization conversion reaches a level of 70% or less, preferably 50 to 70%, more preferably 60 to 65%. As such, when an acrylic copolymer having a polymerization conversion rate of 70% or less is used, low viscosity physical properties can be realized even when the solid content is relatively high compared to a copolymer having a high polymerization conversion rate.

The acrylic copolymer of the present invention prepared as described above has a weight average molecular weight of 500,000 to 1,000,000, preferably 600,000 to 1,000,000, more preferably 700,000 to 1,000,000. When the weight average molecular weight of the acrylic copolymer is less than 500,000, there is a problem in that the cohesive force of the adhesive is insufficient due to the decrease in curing efficiency, so that the re-peelability property is deteriorated, and the durability under high temperature or high temperature/high humidity environment is deteriorated, as [Formula 1] When a copolymer of 1,000,000 or more is polymerized using the expressed monomer, there is a possibility that the viscosity will increase and an abnormality may occur in the coating properties.

Meanwhile, the polymerization method is not particularly limited, and various polymerization methods known in the art may be used, for example, polymerization methods such as solution polymerization, photopolymerization, bulk polymerization, suspension polymerization, or emulsion polymerization. A polymerization initiator, molecular weight control, etc. may be additionally added during the polymerization, and the input timing of each component is not particularly limited. That is, the components may be added in batches, or may be divided and added several times.

In the present invention, in particular, the acrylic copolymer can be prepared using a solution polymerization method, and the solution polymerization is preferably performed at a polymerization temperature of 50° C. to 140° C. by adding an initiator in a state in which each monomer is uniformly mixed. do. Examples of the initiator that can be used in this process include azo initiators such as azobisisobutyronitrile or azobiscyclohexane carbonitrile; and/or a conventional initiator such as a peroxide such as benzoyl peroxide or acetyl peroxide, and one or a mixture of two or more of the above may be used, but the present invention is not limited thereto. In addition, as the molecular weight modifier, mercaptans such as t-dodecyl mercaptan or n-dodecyl mercaptan, defentin, or terpenes of t-terpene, chloroform, or a halogenated hydrocarbon of carbon tetrachloride, or pentaerythritol Tetrakis 3-mercapto propionate may be used, but is not limited thereto.

In addition, the acrylic copolymer of the present invention has a branched polymer structure. Since the acrylic copolymer having a branched polymer structure has lower viscosity characteristics than the linear acrylic copolymer having the same weight average molecular weight, the pressure-sensitive adhesive composition including the same can implement excellent coating properties even when the solid content is high.

(2) multifunctionality hardener

On the other hand, the pressure-sensitive adhesive composition of the present invention may further include a polyfunctional curing agent together with the acrylic copolymer.

The multifunctional curing agent is for improving the interfacial adhesion with the substrate, the type is not particularly limited, and various curing agents used in the art, for example, isocyanate compounds, epoxy compounds, aziridine compounds, and At least one selected from the group consisting of metal chelate-based compounds may be used.

As the isocyanate-based compound, a conventional compound known in the art may be used, for example, toluene diisocyanate, 2,4-trylene diisocyanate, 2,6-trylene diisocyanate, hydrogenated torylene diisocyanate, Isoform diisocyanate, 1,3-xylene diisocyanate, 1,4-xylene diisocyanate, diphenylmethane-4,4-diisocyanate, 1,3-bisisocyanatomethyl cyclohexane, tetramethylxylene diisocyanate, 1 ,5-naphthalene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethyl hexamethylene diisocyanate, 2,4,4-trimethyl hexamethylene diisocyanate, trimethylolpropane modified toluene diisocyanate, trimethylolpropane modified tolylene diisocyanate, torylene diisocyanate adduct of trimethylolpropane, xylene diisocyanate adduct of trimethylolpropane, triphenylmethanetoisocyanate, methylenebistriisocyanate, polyols (trimethylolpropane) or mixtures thereof, etc. Can be used.

Examples of the epoxy compound include ethylene glycol diglycidyl ether, triglycidyl ether, trimethylolpropane triglycidyl ether, N,N,N',N'-tetraglycidylethylenediamine, glycerin Diglycidyl ether or a mixture thereof may be used.

Examples of the aziridine-based compound include N,N'-toluene-2.4-bis(1-aziridinecarboxamide), N,N'-diphenylmethane-4,4'-bis(1-aziri). dincarboxamide), triethylene melamine, bisisoprotaloyl-1-(2-methylaziridine), tri-1-aziridinylphosphine oxide, or a mixture thereof.

Examples of the metal chelate-based compound include compounds in which a polyvalent metal such as aluminum, iron, zinc, tin, titanium, antimony, magnesium and/or vanadium is coordinated with acetyl acetone or ethyl acetoacetate, etc. , but is not limited thereto.

The polyfunctional curing agent is preferably included in an amount of 0.001 to 0.1 parts by weight, preferably 0.005 to 0.1 parts by weight, based on 100 parts by weight of the acrylic copolymer. In the case of the acrylic pressure-sensitive adhesive composition of the present invention, since the unsaturated hydrocarbon group remaining inside the acrylic copolymer reacts to form a cross-linked structure during the formation of the pressure-sensitive adhesive layer, there is no need to include an excessive amount of a curing agent to form the cross-linked structure, and For the purpose of improving interfacial adhesion, only a small amount of a curing agent is included. When the content of the multifunctional curing agent is less than 0.001 parts by weight, the effect of improving adhesion to the substrate is insignificant, and when it exceeds 0.1 parts by weight, changes in the physical properties of the pressure-sensitive adhesive may occur over time. As described above, since the pressure-sensitive adhesive composition according to the present invention contains a very small amount of the multifunctional curing agent, changes in physical properties of the pressure-sensitive adhesive layer due to residual curing agent over time are effectively suppressed.

(3) other ingredients

The pressure-sensitive adhesive composition of the present invention may further include other components such as a solvent, a silane coupling agent, a tackifying resin, an additive, and the like, in addition to the above-described components for controlling physical properties.

The pressure-sensitive adhesive composition of the present invention may further include a solvent for viscosity control. The solvent may be a polymerization solvent used in the process of preparing the acrylic copolymer, or may be a diluent solvent added for viscosity control if necessary. The solvent may include, for example, ethyl acetate, n-pentane, isopentane, neopentane, n-hexane, n-octane, n-heptane, methyl ethyl ketone, acetone, toluene, or a combination thereof. However, the present invention is not limited thereto. The solvent may be included in an amount such that the solid content in the pressure-sensitive adhesive composition is 30% by weight or more, preferably 30 to 60% by weight.

The pressure-sensitive adhesive composition of the present invention may further include a silane coupling agent. The silane coupling agent improves adhesion and adhesion stability between the pressure-sensitive adhesive and the glass substrate, improves heat resistance and moisture resistance, and also improves adhesion reliability when the pressure-sensitive adhesive is left for a long time under high temperature and/or high humidity conditions. . Examples of the coupling agent that can be used in the present invention include γ-glycidoxypropyl triethoxy silane, γ-glycidoxypropyl trimethoxy silane, γ-glycidoxypropyl methyldiethoxy silane, γ-glycidoxy propyl triethoxy silane, 3-mercaptopropyl trimethoxy silane, vinyltrimethoxysilane, vinyltriethoxy silane, γ-methacryloxypropyl trimethoxy silane, γ-methacryloxypropyl triethoxy silane, γ-aminopropyl trimethoxy silane, γ-aminopropyl triethoxy silane, 3-isocyanatopropyl triethoxy silane, γ-acetoacetatepropyl trimethoxysilane, γ-acetoacetatepropyl triethoxy silane, and β-cyanoacetyl trimethoxy silane, β-cyanoacetyl triethoxy silane, and acetoxyaceto trimethoxy silane, and one or a mixture of two or more of them may be used. In the present invention, it is preferable to use a silane-based coupling agent having an acetoacetate group or a β-cyanoacetyl group, but is not limited thereto. In the composition of the present invention, the silane-based coupling agent may be included in an amount of 0.01 parts by weight to 5 parts by weight, preferably 0.01 parts by weight to 1 part by weight, based on 100 parts by weight of the acrylic copolymer. If the content of the coupling agent is less than 0.01 parts by weight, the effect of increasing the adhesive strength is insignificant, and when it exceeds 5 parts by weight, there is a risk of lowering durability.

The pressure-sensitive adhesive composition of the present invention may further include 1 part by weight to 100 parts by weight of a tackifying resin based on 100 parts by weight of the acrylic copolymer from the viewpoint of adjusting the adhesive performance. The kind of such tackifying resin is not particularly limited, and for example, (hydrogenated) hydrocarbon-based resin, (hydrogenated) rosin resin, (hydrogenated) rosin ester resin, (hydrogenated) terpene resin, (hydrogenated) terpene phenol resin, One kind or a mixture of two or more kinds of polymerized rosin resin or polymerized rosin ester resin may be used. When the content of the tackifying resin is less than 1 part by weight, there is a fear that the effect of addition is insignificant, and when it exceeds 100 parts by weight, there is a fear that the compatibility and/or the effect of improving cohesion may be reduced.

The pressure-sensitive adhesive composition of the present invention also includes one or more additives selected from the group consisting of an epoxy resin, a curing agent, a UV stabilizer, an antioxidant, a colorant, a reinforcing agent, a filler, an antifoaming agent, a surfactant, and a plasticizer to the extent that the effect of the invention is not affected. may further include.

The acrylic pressure-sensitive adhesive composition according to the present invention uses an acrylic copolymer having a low polymerization conversion rate and uses an unsaturated hydrocarbon functional group remaining in the copolymer to allow an additional crosslinking reaction to proceed when forming an adhesive layer, thereby significantly reducing the amount of curing agent used compared to the prior art. In this way, it is possible to effectively suppress the occurrence of changes over time in the adhesive layer due to the unreacted curing agent.

In addition, the acrylic pressure-sensitive adhesive composition according to the present invention has a low polymerization conversion rate and uses an acrylic copolymer having a branched polymer structure, compared to the pressure-sensitive adhesive composition using an acrylic copolymer having a linear polymer structure having the same level of weight average molecular weight. Low viscosity can be realized. Specifically, the pressure-sensitive adhesive composition according to the present invention has a viscosity of 3,000 cP or less at 23° C., preferably 1,000 cP to 3,000 cP, when the solid content is 30 wt % or more, for example, 30 to 60 wt %. , more preferably as low as 1,000 cP to 2,000 cP. In this case, the solid content may refer to the solid content at the time when the pressure-sensitive adhesive composition of the present invention is prepared in the form of a coating solution or the like, and is applied to the manufacturing process of the pressure-sensitive adhesive. As described above, when the pressure-sensitive adhesive composition of the present invention is used, it is possible to increase the solid content in the coating solution without deteriorating the coating property, so that not only the productivity is excellent, but also precise control of the thickness and the like is possible.

On the other hand, in the case of the conventional acrylic pressure-sensitive adhesive composition, an acrylic copolymer having a high weight average molecular weight was used to realize physical properties such as long-term durability. there was. Accordingly, in the prior art, it was necessary to undergo a dilution process of lowering the viscosity by adding a solvent compatible with the acrylic copolymer to the pressure-sensitive adhesive composition. However, since the acrylic pressure-sensitive adhesive composition of the present invention has a low viscosity, it is not necessary to undergo a separate dilution process, or because only a small amount of a dilution solvent is used, processability and productivity are excellent. In addition, the acrylic pressure-sensitive adhesive composition according to the present invention has the advantage that, upon completion of the formation of the pressure-sensitive adhesive layer, crosslinking is completed by itself, so that a special aging time is not required to improve the cohesive force inside the polymer.

Polarizer

Next, a polarizing plate according to the present invention will be described.

The present invention also provides a polarizing film; and a pressure-sensitive adhesive layer formed on one or both sides of the polarizing film and containing a cured product of the pressure-sensitive adhesive composition according to the present invention.

The type of the polarizing film used in the present invention is not particularly limited, and a general type known in this field may be employed. For example, the polarizing film may include a polarizer; and a protective film formed on one or both surfaces of the polarizer.

The type of polarizer included in the polarizing plate of the present invention is not particularly limited, and, for example, a general type known in this field, such as polyvinyl alcohol-based polarizer, may be employed without limitation.

A polarizer is a functional film or sheet capable of extracting only light vibrating in one direction from incident light while vibrating in multiple directions. Such a polarizer may be, for example, a form in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film. Polyvinyl alcohol-type resin which comprises a polarizer can be obtained by gelatinizing polyvinyl acetate-type resin, for example. In this case, the polyvinyl acetate-based resin that can be used may include not only a homopolymer of vinyl acetate, but also a copolymer of vinyl acetate and other monomers copolymerizable therewith. In the above, examples of the monomer copolymerizable with vinyl acetate include one or a mixture of two or more of unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group. not. The degree of gelation of the polyvinyl alcohol-based resin may be usually about 85 mol% to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be further modified, for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. In addition, the degree of polymerization of the polyvinyl alcohol-based resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000. The polyvinyl alcohol-based resin as described above can be formed into a film and used as a raw film of a polarizer. A method of forming the polyvinyl alcohol-based resin into a film is not particularly limited, and a general method known in this field may be used.

The thickness of the raw film formed of the polyvinyl alcohol-based resin is not particularly limited, and for example, may be appropriately controlled within the range of 1 µm to 150 µm. In consideration of ease of stretching, etc., the thickness of the raw film may be controlled to 10 μm or more.

The polarizer is a step of stretching (ex. uniaxial stretching) the polyvinyl alcohol-based resin film as described above, dyeing the polyvinyl alcohol-based resin film with a dichroic dye, adsorbing the dichroic dye, and adsorbing the dichroic dye The polyvinyl alcohol-based resin film can be manufactured through a process of treating the polyvinyl alcohol-based resin film with an aqueous solution of boric acid and a process of washing with water after treatment with an aqueous solution of boric acid. In the above, as the dichroic dye, iodine or a dichroic organic dye may be used.

The polarizing film of the present invention may further include a protective film formed on one or both surfaces of the polarizer. The kind of protective film that may be included in the polarizing plate of the present invention is not particularly limited, and for example, a cellulose-based film such as triacetyl cellulose; polyester-based films such as polycarbonate films or polyethylene terephthalate films; polyether sulfone-based film; and/or a polyethylene film, a polypropylene film, or a polyolefin film having a cyclo- or norbornene structure, or a polyolefin-based film such as an ethylene propylene copolymer may be formed as a multilayer film in which a protective film is laminated. At this time, the thickness of the protective film is also not particularly limited, and may be formed in a conventional thickness.

On the other hand, in the present invention, the method of forming the pressure-sensitive adhesive layer on the polarizing film is not particularly limited, and for example, a method of applying the pressure-sensitive adhesive composition (coating solution) to the film or device by a conventional means such as a bar coater and heat curing, Alternatively, a method in which the pressure-sensitive adhesive composition is once applied to the surface of a releasable substrate and heat-cured, and then the formed pressure-sensitive adhesive layer is transferred to the surface of a polarizing film or device, etc. may be used.

In the present invention, the process of forming the pressure-sensitive adhesive layer is also preferably performed after sufficiently removing the bubble-inducing components such as volatile components or reaction residues inside the pressure-sensitive adhesive composition (coating solution). Accordingly, the crosslinking density or molecular weight of the pressure-sensitive adhesive is too low, and the elastic modulus is lowered, and bubbles present between the glass plate and the pressure-sensitive adhesive layer become large at a high temperature, thereby preventing problems such as forming a scatterer inside.

On the other hand, the pressure-sensitive adhesive layer formed as described above has a sol molecular weight of 200,000 to 400,000, preferably 250,000 to 350,000. The sol molecular weight is a value that is changed according to the polymerization conversion of the acrylic copolymer before curing.

Meanwhile, the molecular weight of the sol is the molecular weight of a residue remaining after dissolving the adhesive layer in an organic solvent and then volatilizing the organic solvent through a drying process. Specifically, the sol molecular weight may be measured by the following method. First, the pressure-sensitive adhesive composition of the present invention is applied between two release films, sufficiently heat-cured at 120° C. for 10 minutes to form an adhesive layer, and aged under constant temperature and humidity conditions for 3 days. Then, the release films are separated from the adhesive layer, and about 0.3 g to 0.5 g of the adhesive layer is collected, put in a 200 mesh wire mesh, placed in a container containing ethyl acetate, and left to dissolve for more than 48 hours, then heated to 80°C. Dry the solvent to volatilize. Thereafter, the weight average molecular weight of the dried sample is measured through GPC, and this is referred to as the sol molecular weight.

The polarizing plate of the present invention may further include one or more functional layers selected from the group consisting of a protective layer, a reflective layer, an anti-glare layer, a retardation plate, a wide viewing angle compensation film, and a luminance enhancing film.

The polarizing plate according to the present invention as described above hardly changes over time of the adhesive layer, and has excellent durability even under high temperature or high temperature/high humidity conditions.

Specifically, the polarizing plate has a creep distance (Creep) change rate defined by the following formula (1) of 5% or less, preferably 3% or less.

Equation (1): Push distance change rate (%)= (T ₀ -T ₁ /T ₀ )×100

In Equation (1), T ₀ is a sliding distance measured after manufacturing a measurement specimen by attaching the polarizing plate to a glass substrate, and storing the measurement specimen at 23° C. and 50% RH for 4 days, T ₁ denotes the rolling distance measured after the specimen for measurement was stored for 4 days at 23° C. and 50% RH, and further aged at 80° C. for 1 day.

In addition, the polarizing plate according to the present invention has an adhesive force change rate defined by the following formula (2) of 5% or less, preferably 4% or less.

Equation (2): Adhesion change rate (%) = (B ₀ -B ₁ /B ₀ )×100

In Equation (2), B ₀ is a sample prepared by attaching the polarizing plate to a glass substrate after storing the polarizing plate at 23° C., 50%RH conditions for 4 hours at 23° C., 50%RH conditions for 4 hours. After storage, the adhesive force measured by pulling the polarizing plate under the conditions of a peeling rate of 300 mm/min and a peeling angle of 180 degrees, B ₁ is the sample stored at 23°C and 50%RH for 4 hours, and then 80°C This is the adhesive force measured by pulling the polarizing plate under the conditions of a peeling rate of 300 mm/min and a peeling angle of 180 degrees after further aging for 1 day.

display device

Next, the display device of the present invention will be described.

The display device of the present invention includes the above-described polarizing plate according to the present invention.

More specifically, the display device may be a liquid crystal display device including a liquid crystal panel in which the polarizing plate according to the present invention is bonded to one or both surfaces. In this case, the type of the liquid crystal panel is not particularly limited. In the present invention, for example, without being limited to the type, F various passive matrices including TN (Twisted Neumatic) type, STN (Super Twisted Neumatic) type, F (ferroelectric) type and PD (polymer dispersed LCD) type, etc. method; Various active matrix methods, including two-terminal and three-terminal; Any known liquid crystal panel including a horizontal electric field type (IPS mode) panel and a vertical alignment type (VA mode) panel may be applied. In addition, the type of other components included in the liquid crystal display of the present invention and the manufacturing method thereof are not particularly limited, and general configurations in this field may be employed without limitation.

Next, the present invention will be described in more detail through specific examples.

production example 1: Preparation of acrylic copolymer (A)

96.9 parts by weight of butyl acrylate (BA) and 96.9 parts by weight of hydroxyethyl acrylate (HEA) based on 100 parts by weight of the alkyl (meth)acrylate-based monomer mixture in a 3L reactor in which nitrogen gas is refluxed and a cooling device is installed for easy temperature control ) 0.1 parts by weight of a monomer mixture containing 3 parts by weight of allyl methacrylate (AMA) was added, and then 53 parts by weight of ethyl acetate (EAc) as a solvent was added. Then, nitrogen gas was purged for 60 minutes to remove oxygen ( After purging), the temperature was maintained at 70°C.

Then, 0.68 parts by weight of n-dodecylmercaptan (n-DDM) as a molecular weight regulator and 0.02 parts by weight of V-65 (Azobis(2-4-dimethylvaleronitrile), manufactured by Wako) as a reaction initiator were added, and the polymerization conversion rate was 62%. The reaction was carried out until the acrylic copolymer (A) was prepared. The molecular weight regulator was added in 5 divided doses during the reaction time.

production example 2: Preparation of acrylic copolymer (B)

In a 3L reactor in which nitrogen gas is refluxed and a cooling device is installed for easy temperature control, 92.9 parts by weight of butyl acrylate (BA) and 92.9 parts by weight of hydroxyethyl acrylate (HEA) based on 100 parts by weight of the alkyl (meth)acrylate-based monomer mixture ) 0.1 parts by weight of a monomer mixture containing 7 parts by weight of allyl methacrylate (AMA) was added, and then 60 parts by weight of ethyl acetate (EAc) was added as a solvent. Then, nitrogen gas was purged for 60 minutes to remove oxygen ( After purging), the temperature was maintained at 70°C.

Thereafter, 0.59 parts by weight of n-dodecylmercaptan (n-DDM) as a molecular weight modifier and 0.02 parts by weight of V-65 (Azobis(2-4-dimethylvaleronitrile), manufactured by Wako) as a reaction initiator were added while the reaction was carried out to polymerization. An acrylic copolymer (B) having a conversion rate of 64% was prepared. At this time, the molecular weight modifier was added in 5 divided doses during the reaction time.

production example 3: Preparation of acrylic copolymer (C)

A monomer mixture containing 98 parts by weight of butyl acrylate (BA) and 2 parts by weight of hydroxyethyl acrylate (HEA) is added to a 3L reactor in which nitrogen gas is refluxed and a cooling device is installed to facilitate temperature control, and the solvent is used as a solvent. 50 parts by weight of ethyl acetate (EAc) was added. Then, nitrogen gas was purged for 60 minutes to remove oxygen, and then the temperature was maintained at 64°C. Then, 0.04 parts by weight of n-dodecyl mercaptan (n-DDM) as a molecular weight regulator and 0.04 parts by weight of azobis (isobutylnitrile (V-60, manufacturer: Junsei) as a polymerization initiator are added, and the polymerization conversion rate will be 75%. until reacted to prepare an acrylic copolymer (C).

production example 4: Preparation of acrylic copolymer (D)

A monomer mixture containing 98 parts by weight of butyl acrylate (BA) and 2 parts by weight of hydroxyethyl acrylate (HEA) is added to a 3L reactor in which nitrogen gas is refluxed and a cooling device is installed to facilitate temperature control, and the solvent is used as a solvent. 50 parts by weight of ethyl acetate (EAc) was added. Then, nitrogen gas was purged for 60 minutes to remove oxygen, and then the temperature was maintained at 64°C. Then, 0.0375 parts by weight of n-dodecyl mercaptan (n-DDM) as a molecular weight regulator and 0.04 parts by weight of azobis (isobutylnitrile (V-60, manufacturer: Junsei) as a polymerization initiator were additionally added, and the polymerization conversion rate was 77% By reacting until the acrylic copolymer (D) was prepared.

production example 5: Preparation of acrylic copolymer (E)

A monomer mixture containing 98 parts by weight of butyl acrylate (BA) and 2 parts by weight of hydroxyethyl acrylate (HEA) is added to a 3L reactor in which nitrogen gas is refluxed and a cooling device is installed to facilitate temperature control, and the solvent is used as a solvent. 50 parts by weight of ethyl acetate (EAc) was added. Then, nitrogen gas was purged for 60 minutes to remove oxygen, and then the temperature was maintained at 64°C. Then, 0.035 parts by weight of n-dodecyl mercaptan (n-DDM) as a molecular weight regulator and 0.04 parts by weight of azobis (isobutylnitrile (V-60, manufacturer: Junsei) as a polymerization initiator were additionally added, and the polymerization conversion rate was 75% It was reacted until the acrylic copolymer (E) was prepared.

production example 6: Preparation of acrylic copolymer (F)

A monomer mixture containing 98 parts by weight of butyl acrylate (BA) and 2 parts by weight of hydroxyethyl acrylate (HEA) is added to a 3L reactor in which nitrogen gas is refluxed and a cooling device is installed to facilitate temperature control, and the solvent is used as a solvent. 50 parts by weight of ethyl acetate (EAc) was added. Then, nitrogen gas was purged for 60 minutes to remove oxygen, and then the temperature was maintained at 64°C. Then, 0.04 parts by weight of n-dodecyl mercaptan (n-DDM) as a molecular weight regulator and 0.04 parts by weight of azobis (isobutylnitrile (V-60, manufacturer: Junsei) as a polymerization initiator until the polymerization conversion rate is 63%. An acrylic copolymer (F) was prepared.

The weight average molecular weight and polymer structure of the acrylic copolymers prepared in Preparation Examples 1 to 6 were measured as follows and shown in Table 1.

(1) The weight average molecular weight was measured using GPC under the following conditions. The measurement results were converted using standard polystyrene of Agilent system to prepare the calibration curve.

<Measurement conditions>

Meter: Agilent GPC (Agulent 1200 series, USA)

Column: Connect 2 PL Mixed B

Column temperature: 40°C

Eluent: Tetrohydrofuran

Flow rate: 1.0 mL/min

Concentration: ~ 1 mg/mL (100 μL injection)

(2) The polymer structure was evaluated as follows.

First, the same kind of alkyl (meth)acrylate-based monomer and (meth)acrylic-based monomer having a crosslinkable functional group as used in the acrylic copolymer to be evaluated for the polymer structure (hereinafter referred to as 'evaluation target copolymer') The mixture was mixed to prepare a monomer mixture. At this time, the content of the (meth)acrylic monomer having a crosslinkable functional group in the monomer mixture was made equal to the content of the (meth)acrylic monomer having a crosslinkable functional group in the copolymer to be evaluated. Then, the monomer mixture was polymerized to prepare an acrylic copolymer (hereinafter, referred to as a 'reference copolymer') having a weight average molecular weight (error range ±5%) equivalent to that of the copolymer to be evaluated.

Thereafter, ethyl acetate solvent was added to each of the reference copolymer and the copolymer to be evaluated to adjust the solid content concentration to 30%, and then the viscosity was measured. If the viscosity of the evaluation target copolymer measured as described above has a viscosity that is 30% or more lower than that of the reference copolymer, it is evaluated as having a branched polymer structure, and in other cases, it is evaluated as having a linear polymer structure. .

Preparation Example 1 Preparation 2 Preparation 3 Preparation 4 Preparation 5 Preparation 6 sample A B C D E F Furtherance BA 96.9 92.9 98.0 98.0 98.0 98.0 HEA 0.1 0.1 2.0 2.0 2.0 2.0 AMA 3.0 7.0 0 0 0 0 Polymerization conversion (%) 62 64 75 77 75 63 Weight average molecular weight (Mw) 820,000 870,000 800,000 830,000 850,000 720,000 polymer structure branched branched linear linear linear linear

Example One

Based on 100 parts by weight of the acrylic copolymer A prepared in Preparation Example 1, 0.01 parts by weight of a polyfunctional crosslinking agent (coronate L, manufactured by Nippon Polyurethane), a silane coupling agent (beta-cyanoacetyl group-containing silane coupling agent (LG Chem) , M812) 0.2 parts by weight was blended and uniformly mixed to prepare a pressure-sensitive adhesive composition.The prepared pressure-sensitive adhesive composition had a solid content of 30% by weight.

The prepared pressure-sensitive adhesive composition was applied to a polyethylene terephthalate film (release PET) having a thickness of 38 μm treated with silicone peeling, and dried at a temperature of 120° C. for 10 minutes or more so that the thickness after drying was 23 μm, to form an adhesive coating layer . Thereafter, the adhesive coating layer was laminated on a conventional polarizing plate to prepare a polarizing plate including an adhesive layer.

Example 2

A pressure-sensitive adhesive composition and a polarizing plate were prepared in the same manner as in Example 1, except that the acrylic copolymer B prepared in Preparation Example 2 was used instead of the acrylic copolymer A.

comparative example One

Based on 100 parts by weight of the acrylic copolymer C prepared in Preparation Example 3, 0.01 parts by weight of a polyfunctional crosslinking agent (coronate L, manufactured by Nippon Polyurethane), a silane coupling agent (beta-cyanoacetyl group-containing silane coupling agent (LG Chem) , M812) and 0.01 parts by weight of a crosslinking catalyst (DBTDL, Sigma-Aldrich) were mixed, and ethyl acetate was further added to prepare a pressure-sensitive adhesive composition having a solid content of 23% by weight.

The prepared pressure-sensitive adhesive composition was coated on a polyethylene terephthalate film (release PET) having a thickness of 38 μm treated with silicone peeling and dried at a temperature of 120° C. for 10 minutes or more so that the thickness after drying became 23 μm, to form an adhesive coating layer. . Thereafter, the adhesive coating layer was laminated on a conventional polarizing plate to prepare a polarizing plate including an adhesive layer.

comparative example 2

Use the acrylic copolymer D prepared in Preparation Example 4 instead of the acrylic copolymer C, and the polyfunctional crosslinking agent (coronate L, manufactured by Nippon Polyurethane) was blended in 0.25 parts by weight based on 100 parts by weight of the acrylic resin D except for the point prepared a pressure-sensitive adhesive composition and a polarizing plate in the same manner as in Comparative Example 1.

comparative example 3

Using the acrylic copolymer E prepared in Preparation Example 5 instead of the acrylic copolymer C, and 0.35 parts by weight of the polyfunctional crosslinking agent (coronate L, manufactured by Nippon Polyurethane Co., Ltd.) based on 100 parts by weight of the acrylic resin E. Except for the point prepared a pressure-sensitive adhesive composition and a polarizing plate in the same manner as in Comparative Example 1.

comparative example 4

Instead of using the acrylic copolymer F prepared in Preparation Example 5 instead of the acrylic copolymer C, the polyfunctional crosslinking agent (coronate L, manufactured by Nippon Polyurethane) was blended in 0.25 parts by weight based on 100 parts by weight of the acrylic resin F except for the point prepared a pressure-sensitive adhesive composition and a polarizing plate in the same manner as in Comparative Example 1.

The physical properties of the pressure-sensitive adhesive composition and the polarizing plate prepared in Examples 1 to 2 and Comparative Examples 1 to 4 were measured by the following method, and the measurement results are shown in Table 2 below.

How to measure physical properties

(1) Coating viscosity (unit: cP)

The coating viscosity of the pressure-sensitive adhesive composition prepared in Examples and Comparative Examples was measured according to the following procedure using a Brookfield digital viscometer (RV DV2T).

Put about 220 mL of the pressure-sensitive adhesive composition into a 250 mL PE bottle, close the lid so that the solvent does not volatilize, seal it sufficiently with parafilm, etc., and then leave it sufficiently under constant temperature/humidity (23° C., 50% relative humidity) conditions to remove air bubbles. Then, after removing the seal and lid, a spindle was placed at an angle to prevent bubbles from forming in the pressure-sensitive adhesive composition, the spindle was connected to a viscometer, and the liquid level of the pressure-sensitive adhesive composition was adjusted to fit into the groove of the spindle. Then, the viscosity was measured under the rpm condition in which the torque was 20% (±1%).

(2) coatability

When the pressure-sensitive adhesive composition prepared in Examples and Comparative Examples was coated on a polyethylene terephthalate film, the state of the coating layer was visually observed and evaluated according to the following criteria.

<Coatability Evaluation Criteria>

○: Bubbles, streaks, etc. were not visually confirmed in the coating layer.

Δ: Fine bubbles and/or streaks were observed in the coating layer with the naked eye.

(3) Creep distance (Unit: ㎛)

A specimen is prepared by cutting the polarizing plate prepared in Examples and Comparative Examples to have a width of 10 mm and a length of 10 mm. Then, the release PET film attached to the pressure-sensitive adhesive layer was peeled off, and the specimen was attached to alkali-free glass using a roller of 2 kg according to JIS Z 0237 to prepare a measurement specimen. The specimen for measurement was stored for 4 days under constant temperature and humidity conditions (23° C., 50% R.H.), and then the pushing distance was measured using TA equipment (Texture Analyzer, Stable Microsystems Co., UK). At this time, the creep distance (Creep) was measured as the distance (unit: μm) that the polarizing plate was pushed from the glass substrate when the polarizing plate of the measurement specimen was pulled for 1,000 seconds under a load of 1,000 g.

In addition, the specimen for measurement was stored for 4 days under constant temperature and humidity conditions (23° C., 50% R.H.), and then further aged at 80° C. for 1 day, and then the pushing distance was measured in the same manner.

(4) room temperature adhesion

After storing the polarizing plate prepared in Examples and Comparative Examples under constant temperature and humidity conditions (23° C., 50% R.H.) for 4 days, the polarizing plate was attached to a glass substrate to prepare a measurement specimen.

Then, after storing the specimen for measurement under constant temperature and humidity conditions (23° C., 50% R.H.) for 4 hours, pull the polarizing plate under the conditions of a peeling rate of 300 mm/min and a peeling angle of 180 degrees to completely separate the polarizing plate from the glass substrate. By measuring the force required to make it, room temperature adhesive force (unit: gf/25mm) was measured.

In addition, the specimen for measurement was stored for 4 hours under constant temperature and humidity conditions (23° C., 50% R.H.) as above, and then further aged at 80° C. for 1 day, and then room temperature adhesion was measured in the same manner.

(5) Adhesion to the substrate

After storing the polarizing plates prepared in Examples and Comparative Examples under constant temperature and humidity conditions (23° C., 50% R.H.) for 4 days, a paper tape (American Tape (Made IN USA) having an adhesive layer was applied on the adhesive layer of the polarizing plate. , and after 1 hour or more had elapsed, the paper tape was peeled off, and the adhesion to the substrate was determined according to the following evaluation criteria.

<Evaluation criteria>

OK: The polarizing plate adhesive layer is not transferred on the paper tape

NG: polarizing plate adhesive layer transferred on paper tape

(6) Durability evaluation

A sample was prepared by cutting the polarizing plate prepared in Examples and Comparative Examples to a size of 180 mm × 250 mm (length × width), and the sample was attached to a 19-inch commercial panel using a laminator. Thereafter, the panel was pressed in an autoclave (50° C. and 5 atm) for about 20 minutes, and then stored for 24 hours under constant temperature and humidity conditions (23° C., 50% R.H.) to prepare a specimen.

The heat-and-moisture durability of the prepared specimens was evaluated by leaving the specimen at a temperature of 60° C. and a relative humidity of 90% R.H. for 500 hours, and then observing whether bubbles or peeling occurred at the adhesive layer interface. The silver specimen was left at a temperature of 80° C. for 500 hours, and then, it was evaluated by observing whether bubbles or peeling occurred.

<Evaluation criteria>

○: No bubbles and no peeling

△: slight generation of bubbles and/or peeling

×: A large amount of bubbles and/or peeling occurred

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Furtherance
(parts by weight) Acrylic copolymer A B C D E F 100 100 100 100 100 100 Multifunctional curing agent 0.01 0.01 0.01 0.25 0.35 0.25 crosslinking catalyst - - 0.01 0.01 0.01 0.01 Silane Coupling Agent 0.2 0.2 0.2 0.2 0.2 0.2 Solid content (%) 30 30 23 23 23 30 Coating viscosity (cP) 1850 1530 1870 1900 1920 5200 coatability OK OK OK OK OK X Creep
[um] 4 days later 273 251 leaving out 350 262 Measurable 80℃, 1 day after aging 270 249 leaving out 268 187 rate of change (%) 1.1 0.8 - 23.4 28.6 adhesiveness
[gf/25mm] 4 days later 310 250 1520 430 330 80℃, 1 day after aging 300 245 not measurable 321 210 rate of change (%) 3.2 2.0 - 25.3 36.4 substrate adhesion 4 days later OK OK NG OK NG 80℃, 1 day after aging OK OK NG NG NG durability 4 days later O O X O O 80℃, 1 day after aging O O X X X

As shown in [Table 1], the pressure-sensitive adhesive compositions of Examples 1 and 2 using the acrylic copolymers A and B of the present invention have low viscosity even when the solid content is 30% by weight or more, so it can be confirmed that the coating properties are excellent. have. In addition, the pressure-sensitive adhesive layer formed by using the pressure-sensitive adhesive composition of Examples 1 and 2 showed very low change over time in adhesive properties such as pushing distance, adhesive force, and substrate adhesion, and exhibited excellent durability even in high temperature and high temperature/high humidity environments.

On the other hand, the pressure-sensitive adhesive composition of Comparative Examples 1 to 3 was able to implement a coatable viscosity only when the solid content was lowered to a level of 23 wt%. As shown in Comparative Example 4, when the solid content was at a level of 30 wt %, the coating was impossible due to high viscosity.

In addition, the pressure-sensitive adhesive layer formed by using the pressure-sensitive adhesive composition of Comparative Examples 1 to 3 had a large change in adhesive properties with time, and had poor durability at high temperature and/or high temperature/high humidity conditions.

Claims (14)

An acrylic pressure-sensitive adhesive composition comprising an acrylic copolymer formed by polymerizing a monomer mixture represented by the following [Formula 1], an alkyl (meth) acrylate monomer, and a monomer mixture comprising a (meth) acrylic monomer having a crosslinkable functional group,
The acrylic copolymer has a weight average molecular weight of 500,000 to 1,000,000, and an acrylic pressure-sensitive adhesive composition having a polymerization conversion rate of 70% or less.
[Formula 1]
R ¹ -CH=CR ² -(C=O)-OXY
In Formula 1, R ¹ is hydrogen, a C1 to C6 alkyl group or a C1 to C6 alkenyl group, R ² is hydrogen or a C1 to C10 alkyl group, X is a single bond, a C1 to C10 alkylene group, a C2 to C10 alkenylene group , ether, ester, or a combination thereof, and Y is a vinyl group, an allyl group, or a C3-C10 cycloalkenyl group.
According to claim 1,
The monomer mixture is an acrylic pressure-sensitive adhesive composition comprising 1 to 15 parts by weight of the monomer represented by Formula 1 with respect to 100 parts by weight of the monomer mixture.
According to claim 1,
The monomer represented by [Formula 1] is allyl methacrylate, allyl acrylate, methallyl methacrylate, methallyl acrylate, 3-butenyl Acrylate (3-butenyl acrylate), but-3-enyl-2-methylprop-2-enoate (but-3-enyl-2-methylprop-2-enoate), 2-allyloxyethyl acrylate (2 -allyloxyethyl acrylate, 2-allyloxyethyl methacrylate, 3-allyloxypropyl methacrylate, 3-allyloxypropyl acrylate, 2-allyloxyethoxyethyl 2-allyloxyethoxyethyl methacrylate, 2-allyloxyethoxyethyl acrylate, cyclohex-2-enyl acrylate, cyclo-hex-2-ene -1-yl-2-methylprop-2-enoate (cyclohex-2-en-1-yl 2-methylprop-2-enoate) and 3-vinylcyclohex-2-enyl acrylate (3-vinylcyclohex- 2-enyl acrylate) at least one acrylic pressure-sensitive adhesive composition selected from the group consisting of.
According to claim 1,
The monomer mixture is an acrylic pressure-sensitive adhesive composition comprising 0.01 to 1 part by weight of the (meth)acrylic monomer having the crosslinkable functional group based on 100 parts by weight of the monomer mixture.
According to claim 1,
The monomer mixture is based on 100 parts by weight of the monomer mixture,
84 parts by weight to 98.9 parts by weight of the alkyl (meth)acrylate-based monomer;
0.01 to 1 part by weight of a (meth)acrylic monomer having a crosslinkable functional group; and
An acrylic pressure-sensitive adhesive composition comprising 1 to 15 parts by weight of the monomer represented by the [Formula 1].
According to claim 1,
The pressure-sensitive adhesive composition is an acrylic pressure-sensitive adhesive composition further comprising a multifunctional curing agent.
7. The method of claim 6,
The polyfunctional curing agent is at least one selected from the group consisting of an isocyanate compound, an epoxy compound, an aziridine compound, and a metal chelate compound.
7. The method of claim 6,
The polyfunctional curing agent is an acrylic pressure-sensitive adhesive composition that is included in an amount of 0.001 to 0.1 parts by weight based on 100 parts by weight of the acrylic copolymer.
According to claim 1,
The pressure-sensitive adhesive composition has a solid content of 30% by weight or more,
An acrylic pressure-sensitive adhesive composition having a viscosity of 1000cP to 3000cP at 23°C.
polarizing film; and a pressure-sensitive adhesive layer formed on one or both sides of the polarizing film and comprising a cured product of the acrylic pressure-sensitive adhesive composition of any one of claims 1 to 8.
11. The method of claim 10,
The polarizing plate is a polarizing plate having a creep distance (Creep) change rate of 5% or less, which is defined by the following formula (1).
Equation (1): Push distance change rate (%)= (T ₀ -T ₁ /T ₀ )×100
In Equation (1), T ₀ is a sliding distance measured after manufacturing a measurement specimen by attaching the polarizing plate to a glass substrate, and storing the measurement specimen at 23° C. and 50% RH for 4 days, T ₁ denotes the rolling distance measured after the specimen for measurement was stored for 4 days at 23° C. and 50% RH, and further aged at 80° C. for 1 day.
11. The method of claim 10,
The polarizing plate is a polarizing plate having an adhesive force change rate of 5% or less, which is defined by the following formula (2).
Equation (2): Adhesion change rate (%) = (B ₀ -B ₁ /B ₀ )×100
In the above formula (2),
B ₀ is the sample prepared by attaching the polarizing plate to a glass substrate after storing the polarizing plate at 23°C and 50%RH for 4 days at 23°C, 50%RH, and then storing the sample at 23°C and 50%RH for 4 hours, then peeling rate 300 It is the adhesive force measured by pulling the polarizing plate under the conditions of mm/min and a peeling angle of 180 degrees,
B ₁ is the sample stored at 23 ℃, 50%RH conditions for 4 hours, and then aged (aging) for 1 day at 80 ℃ the polarizing plate under the conditions of a peeling rate of 300 mm / min and a peeling angle of 180 degrees measured by pulling adhesion.
11. The method of claim 10,
The adhesive layer is a polarizing plate having a sol molecular weight of 200,000 to 400,000.
A display device comprising the polarizing plate of claim 10 .