KR20220055864A - Acrylic pressure snsitive adhesive composition, manufacturing method of the same and adhesive member manufactured using the same - Google Patents

Abstract

The objective of the present invention is to provide an acrylic pressure-sensitive adhesive composition for a polarizing plate capable of realizing low viscosity even under a high content of dry solid, a manufacturing method therefor, and a pressure-sensitive adhesive member manufactured using the same. More specifically, one embodiment of the present invention provides an acrylic pressure-sensitive adhesive composition in which the type and mixing ratio of repeating units constituting an acrylic copolymer, the structure, molecular weight, and polymerization conversion rate of the acrylic copolymer are controlled.

Description

Acrylic pressure-sensitive adhesive composition, manufacturing method thereof, and adhesive member manufactured using the same

The present invention relates to an acrylic pressure-sensitive adhesive composition, a method for preparing the same, and a pressure-sensitive adhesive member manufactured using the same.

An adhesive (Pressure-Sensitive Adhesive, PSA) is a material that has the property of adhering to an adherend with a small pressure. It is a viscoelastic material that is different from adhesives and has basic properties of initial adhesion, adhesion, and cohesion, and is used in various industries such as printing, chemicals, pharmaceuticals, home appliances, automobiles, and stationery.

Among them, as an adhesive used for attaching a liquid crystal cell and a polarizing plate of a liquid crystal display device (LCD), acrylic resin, rubber, urethane resin, silicone resin, EVA (Ethylene Vinyl Acetate), etc. are used. Among them, a pressure-sensitive adhesive based on an acrylic resin having transparency, oxidation resistance and yellowing resistance is widely used.

In particular, among acrylic resins, an acrylic resin having a high weight average molecular weight may be used in order to improve durability and curing efficiency. This is because, when an acrylic resin having a low weight average molecular weight is used, the 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 this regard, as a method for increasing the solid content while maintaining the viscosity of the coating solution at an appropriate level, a method of mixing a low molecular weight substance or increasing the content of an unreacted curing agent has been proposed. However, in the case of the method of mixing low molecular weight substances, the adhesive layer is easy to deform, so when the polarizing plate is stored in a roll form in the polarizing plate manufacturing process, the pressure of the adhesive layer is easy to cause a pit, and when the polarizing plate is cut, the cut There is a problem in that the pressure-sensitive adhesive protrudes from the surface, and thus the polarizing plate is easily contaminated. In addition, when the content of unreacted curing agent is increased, after a certain period of time has elapsed after the polarizing plate is attached to the liquid crystal panel, the adhesive force is greatly increased, making it difficult to rework, and changes in adhesive properties over time due to the effect of the residual curing agent There is a problem that it is easy to become.

Therefore, there is a demand for the development of an acrylic pressure-sensitive adhesive composition for a polarizing plate that can implement low viscosity characteristics even under a high solid content.

An object of the present invention is to provide an acrylic pressure-sensitive adhesive composition for a polarizing plate capable of implementing low viscosity characteristics even under a high solid content, a method for preparing the same, and an adhesive member manufactured using the same.

Specifically, in one embodiment of the present invention, there is provided an acrylic pressure-sensitive adhesive composition in which the type and mixing ratio of the repeating units constituting the acrylic copolymer, the structure of the acrylic copolymer, the molecular weight, and the polymerization conversion are controlled.

In addition, in another embodiment of the present invention, by controlling the type and mixing ratio of the monomer, the type of antioxidant, the input amount and the input time, there is provided a method for preparing the acrylic pressure-sensitive adhesive composition.

Furthermore, in another embodiment of the present invention, an adhesive member and a display device manufactured using the acrylic pressure-sensitive adhesive composition of the embodiment are provided.

The acrylic pressure-sensitive adhesive composition of one embodiment can realize low viscosity characteristics even under a high solids content, and has excellent adhesion and re-peelability change rate, as well as excellent re-peelability properties of the adhesive member and durability in various environments using this. , suitable for application to the polarizing plate of the display device.

In the present invention, terms such as first, second, etc. are used to describe various components, and the terms are used only for the purpose of distinguishing one component from another.

In addition, the terminology used herein is used only to describe exemplary embodiments, and is not intended to limit the present invention.

The singular expression includes the plural expression unless the context clearly dictates otherwise. In this specification, terms such as "comprises", "comprises" or "have" are used to describe embodied features, numbers, steps, components, or combinations thereof, and include one or more other features, numbers, or steps. , components, combinations or additions thereof are not excluded.

In this specification, when each layer or element is referred to as being formed "on" or "over" each layer or element, it means that each layer or element is formed directly on each layer or element, or another layer. or that elements may be additionally formed between each layer, on an object, on a substrate.

In the present specification, unless otherwise defined, "copolymerization" may mean block copolymerization, random copolymerization, graft copolymerization, or alternating copolymerization, and "copolymer" means block copolymer, random copolymer, graft copolymer, or alternating copolymers.

As used herein, the term “copolymer” or “acrylic copolymer” refers to a solid content that is not mixed with a solvent or other additives.

As used herein, the term “monomer mixture” refers to a mixture of substances capable of forming a “copolymer” or “acrylic copolymer” by polymerization, and refers to a solid content that is not mixed with a solvent or other additives.

As used herein, "composition" means a liquid mixture or a solid mixture in which "copolymer" or "acrylic copolymer" is mixed with a solvent, other additives, and the like.

In the present specification, (meth)acrylate is meant to include both acrylate and methacrylate.

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.

Since the present invention may have various changes and may have various forms, specific embodiments will be illustrated and described in detail below. However, this is not intended to limit the present invention to the specific disclosed form, and should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention.

Hereinafter, embodiments of the present invention will be described in detail.

Acrylic copolymer composition

In one embodiment of the present invention, there is provided an acrylic pressure-sensitive adhesive composition in which the type and mixing ratio of the repeating units constituting the acrylic copolymer, the structure of the acrylic copolymer, the molecular weight, and the polymerization conversion are controlled.

Specifically, in the acrylic pressure-sensitive adhesive composition of one embodiment, the acrylic copolymer of one embodiment, based on 100% by weight of the total amount, contains 0.01 to 1% by weight of a first repeating unit derived from a monomer represented by the following Chemical Formula 1, an alkoxy group 5 to 30% by weight of the (meth)acrylic monomer-derived second repeating unit, 0.1 to 15% by weight of the (meth)acrylic monomer-derived third repeating unit containing a crosslinkable functional group, and the remainder of the alkyl (meth)acrylate monomer-derived agent It contains 4 repeating units:

[Formula 1]

R ¹ -CH=CR ² -(C=O)-OXY

In Formula 1,

R ¹ is hydrogen, a C _1-6 alkyl group or a C _1-6 alkenyl group,

R ² is hydrogen or a C _1-10 alkyl group,

X is a single bond; Or, C _1-10 alkylene group, C _2-10 alkenylene group, ether, ester, or a combination of two or more thereof,

Y is a vinyl group, an allyl group, or a C _3-10 cycloalkenyl group.

In addition, in the acrylic pressure-sensitive adhesive composition of the embodiment, the acrylic copolymer has a polymerization conversion of 70% or more, a weight average molecular weight of 1,150,000 to 2,000,000 g/mol, and has a branched polymer structure.

In the acrylic pressure-sensitive adhesive composition of one embodiment, the type and blending ratio of the repeating units constituting the acrylic copolymer, the structure of the acrylic copolymer, the molecular weight, and the polymerization conversion rate are controlled. As a result, low viscosity characteristics can be implemented even under high solids content, The adhesive strength and the rate of change of the re-peelability are excellent, and the re-peelability of the adhesive member and durability in various environments are excellent using the same, and thus it is suitable for application to a polarizing plate of a display device.

However, when any one of the type and blending ratio of the repeating units constituting the acrylic copolymer, the structure of the acrylic copolymer, the molecular weight, and the polymerization conversion does not satisfy the range specified in the embodiment, the acrylic pressure-sensitive adhesive composition and using the same Physical properties of the prepared adhesive member may be deteriorated.

The type and compounding ratio of the repeating unit constituting the acrylic copolymer, the structure, molecular weight and polymerization conversion of the acrylic copolymer, the type and compounding ratio of the monomer, the type of the antioxidant, the input amount and the time of injection are adjusted during the preparation of the acrylic copolymer can be controlled by

Specifically, in the acrylic copolymer, each repeating unit is derived from a monomer. For example, the first repeating unit corresponds to a structural unit formed from the monomer represented by Formula 1 during polymerization on the first polymer.

In this regard, based on the total amount of 100% by weight, 0.01 to 1% by weight of the monomer represented by Formula 1, 5 to 30% by weight of a (meth)acrylic monomer including an alkoxy group, and a (meth)acrylic monomer including a crosslinkable functional group An acrylic copolymer satisfying the content range of the repeating unit may be prepared by polymerizing a monomer mixture containing 0.1 to 15% by weight, and the remainder of the alkyl (meth)acrylate monomer. Here, by the monomer represented by Formula 1, the structure of the acrylic copolymer may be branched.

However, if the weight average molecular weight of the branched acrylic copolymer is to be increased, it is difficult to avoid gelation. For example, when an antioxidant is not added to the monomer mixture in the polymerization process, or an antioxidant including an amine group or a phosphite group is added, gelation may occur.

On the other hand, when a phenolic antioxidant is added in the polymerization process of the monomer mixture, gelation can be suppressed. In particular, in order to form a branched structure stably without gelation while implementing the weight average molecular weight of the acrylic copolymer at a high level of 1,150,000 to 2,000,000 g/mol, the input timing and amount of the phenolic antioxidant can be controlled. can

Specifically, 0.1 to 0.5 parts by weight of the phenolic antioxidant based on 100 parts by weight of the monomer mixture (solid content) may be added when the polymerization conversion of the monomer mixture reaches 50 to 60%. As such, when controlling the input amount and input timing of the phenol-based antioxidant, it is possible to implement a stable branched acrylic copolymer without gelation while having a high weight average molecular weight, and furthermore, it is possible to reach a final polymerization conversion rate of 70% or more.

On the other hand, when the manufacturing process of the acrylic copolymer is performed in the presence of a solvent, an additive, etc., a composition in which the acrylic copolymer is mixed with a solvent, an additive, and the like can be obtained. Of course, after the preparation of the acrylic copolymer, a solvent may be further added for viscosity control and the like.

Hereinafter, the acrylic pressure-sensitive adhesive composition of the embodiment will be described in detail.

Structure, molecular weight and polymerization conversion of acrylic copolymer

Specifically, when the structure of the acrylic copolymer is linear, the curing efficiency is low, the pressure-sensitive adhesive is manufactured, and the content of the unreacted curing agent remaining in the pressure-sensitive adhesive composition is increased. For this reason, it may be difficult to realize the rework characteristic because the adhesive force is too high.

In addition, when the weight average molecular weight of the acrylic copolymer is less than the range specified in the embodiment, curing efficiency is reduced, and durability in severe conditions such as room temperature and low humidity after heat-and-moisture resistance may be reduced.

On the other hand, the acrylic copolymer having a weight average molecular weight of 1,150,000 to 2,000,000 g/mol and having a branched polymer structure can be stably prepared without gelation, and has excellent viscosity, adhesion and re-peelability change rates, By using this, the re-peelability of the adhesive member and durability in various environments are excellent.

Here, the structure and molecular weight of the acrylic copolymer are controllable factors by adjusting the type and mixing ratio of the repeating units constituting the acrylic copolymer. More specifically, the acrylic copolymer having a weight average molecular weight of 1,150,000 to 2,000,000 g/mol and having a branched polymer structure includes 0.01 to 1% by weight of a first repeating unit derived from a monomer represented by Formula 1, and an alkoxy group (meth ) 5 to 30% by weight of a second repeating unit derived from an acrylic monomer, 0.1 to 15% by weight of a third repeating unit derived from a (meth)acrylic monomer containing a crosslinkable functional group, and the remainder of the fourth repeating unit derived from an alkyl (meth)acrylate monomer It can only be implemented when it includes units.

On the other hand, even if the structure of the acrylic copolymer is branched, if the weight average molecular weight is too low, the cohesive force of the adhesive is insufficient due to the decrease in curing efficiency, so that the re-peelability property is reduced, and the durability under high temperature or high temperature / high humidity environment may be reduced. . In addition, if the weight average molecular weight is too high, coating properties may be deteriorated and it may be difficult to prepare a uniform adhesive layer.

In consideration of this tendency, as the acrylic copolymer, the weight average molecular weight is 1,150,000 g/mol or more, 1,170,000 g/mol or more, or 1,200,000 g/mol or more, and 2,000,000 g/mol or less, 1,800,000 g/mol or less, or What is within the range of 1,600,000 g/mol or less can be used.

On the other hand, when preparing the acrylic copolymer, by controlling the input amount and the input time of the phenolic antioxidant, it is possible to prepare a stable branched acrylic copolymer without gelation while having a high weight average molecular weight, and furthermore, 70% or more of final polymerization A conversion rate can be reached as described above.

In this regard, even if the phenolic antioxidant is added at an appropriate time, when the amount exceeds the above-mentioned range, (the type and compounding ratio of the repeating unit, the structure of the acrylic copolymer, and the molecular weight of the acrylic-based antioxidant are controlled within the range of one embodiment) Although copolymers may be prepared, it may be difficult to obtain a final polymerization conversion of 70% or more.

As such, when the final polymerization conversion rate is lowered, since the solid content in the acrylic copolymer composition is also lowered, the productivity compared to the acrylic copolymer prepared in a state where both the input time and the input amount of the phenolic antioxidant are controlled in an appropriate range may be reduced.

In addition, when the final polymerization conversion rate is low, since the production of an acrylic copolymer having a high molecular weight is suppressed, durability may be weakened. For example, the acrylic copolymer prepared by adding the phenolic antioxidant in an amount exceeding the above-mentioned range, compared to the acrylic copolymer prepared in a state where both the input timing and the input amount of the phenolic antioxidant are controlled in an appropriate range, the average Although the average molecular weight itself is within a similar range, the maximum molecular weight may be low, or the content above a specific molecular weight may be low.

On the other hand, while the type and compounding ratio of the repeating units constituting the acrylic copolymer, the structure and molecular weight of the acrylic copolymer are controlled within the range of the embodiment, the polymerization conversion is also controlled within the range (ie, 70% or more) of the embodiment. The acrylic copolymer may have high productivity and excellent durability.

Specifically, the polymerization conversion of the acrylic copolymer may be controlled within a range of 70% or more, 75% or more, or 80% or more, and 99% or less, 95% or less, or 90% by weight or less.

In the present specification, the polymerization conversion may be measured as in Experimental Example 1 to be described later.

Monomer represented by Formula 1

The monomer represented by Chemical Formula 1 is a monomer that contributes to forming the acrylic copolymer having a branched polymer structure.

As pointed out above, when acrylic copolymers having a linear polymer structure are used, as the weight average molecular weight increases, the viscosity also increases, thereby deteriorating workability.

On the other hand, when a monomer mixture containing the monomer represented by Formula 1 is polymerized, an acrylic copolymer having a branched polymer structure is formed, and has lower viscosity characteristics than an acrylic copolymer having a linear polymer structure having the same weight average molecular weight. Because it has, excellent coating properties can be realized even if the solid content in the acrylic pressure-sensitive adhesive composition is increased.

Specifically, the monomer represented by Chemical Formula 1 has two or more ethylene groups in the molecule, so that radicals can be formed by each ethylene group. In the process of free radical polymerization, when radicals are formed by two or more ethylene groups in the monomer molecule represented by Chemical Formula 1, chains can grow in different directions, and thus a branched polymer having two or more chains having different growth directions. will be formed

For example, the monomer represented by Formula 1 is allyl methacrylate, allyl acrylate, methallyl methacrylate, methallyl acrylate, 3-part Tenyl 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-allyloxyethoxy Ethyl methacrylate (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) It may be at least one selected from the group consisting of -2-enyl acrylate).

On the other hand, if the content of the monomer represented by Formula 1 is too small, it is difficult to prepare an acrylic copolymer having low viscosity characteristics. can

In consideration of this tendency, the content of the monomer represented by Chemical Formula 1 is 0.01 wt% or more, 0.05 wt% or more, or 0.1 wt% or more, and 1 wt% or less, 0.8 wt% of 100 wt% of the total amount of the monomer mixture It can be adjusted to less than, 0.6% by weight or less, or 0.5% by weight or less.

The content of the monomer represented by Formula 1 in 100 wt% of the total amount of the monomer mixture may be the same as the content of the repeating unit derived from the monomer represented by Formula 1 in 100 wt% of the total amount of the acrylic copolymer.

(meth)acrylic monomer containing an alkoxy group

The (meth)acrylic monomer containing the alkoxy group is a monomer that promotes a curing reaction in the pressure-sensitive adhesive manufacturing process to improve curing efficiency and increases curing rate, thereby contributing to suppressing changes in adhesive properties over time.

Specifically, the (meth)acrylic monomer containing the alkoxy group is, alkoxy ethylene glycol (meth) acrylic acid ester, alkoxy diethylene glycol (meth) acrylic acid ester, alkoxy triethylene glycol (meth) acrylic acid ester, alkoxy tetraethylene glycol (meth) ) may be at least one selected from the group consisting of acrylic acid ester, alkoxy propylene glycol (meth) acrylic acid ester, alkoxy tripropylene glycol (meth) acrylic acid ester, and alkoxy tetrapropylene glycol (meth) acrylic acid ester, but is not limited thereto. In the above, [alkoxy] represents alkoxy having 1 to 8 carbon atoms, and more specifically, methoxy, ethoxy, propoxy or butoxy.

For example, the (meth)acrylic monomer including the alkoxy group is 2-methoxyethyl acrylate (2-Methoxyethyl acrylate, 2-MTA), ethoxyethoxyethyl acrylate (EEEA), or a mixture thereof can be

On the other hand, when the content of the (meth)acrylic monomer containing the alkoxy group is too low, changes in the adhesive properties of the pressure-sensitive adhesive member prepared using the pressure-sensitive adhesive composition over time occur (for example, causing a decrease in re-peelability) can do. Conversely, if the content of the (meth)acrylic monomer containing the alkoxy group is too high, the content of other alkyl (meth)acrylate monomers that do not include the alkoxy group is relatively decreased, resulting in unexpected change in adhesive properties. there is.

In consideration of this tendency, the content of the (meth)acrylic monomer including the alkoxy group is 5 wt% or more, 30 wt% or less, 25 wt% or less, or 20 wt% or less of 100 wt% of the total amount of the monomer mixture can be adjusted within the range of

The content of the (meth)acrylic monomer including the alkoxy group in 100% by weight of the total amount of the monomer mixture may be the same as the content of the repeating unit derived from the (meth)acrylic monomer including the alkoxy group in 100% by weight of the total amount of the acrylic copolymer.

(meth)acrylic monomer containing a crosslinkable functional group

The (meth)acrylic monomer containing the crosslinkable functional group is for improving the durability, adhesive force and cohesion of the pressure-sensitive adhesive, and the (meth)acrylic monomer is, for example, a hydroxyl group-containing monomer, a carboxyl group-containing monomer or a nitrogen-containing monomer. can be heard

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, 8-hydroxyoctyl (meth)acrylate, 2-hydroxyethylene glycol (meth)acrylate, or 2-hydroxypropylene glycol (meth)acrylate etc. are mentioned.

Examples of the carboxyl group-containing monomer include (meth)acrylic acid, 2-(meth)acryloyloxy acetic acid, 3-(meth)acryloyloxy propyl acid, 4-(meth)acryloyloxy butyric acid, acrylic acid double Sieve, itaconic acid, maleic acid, maleic anhydride, and the like.

In addition, examples of the nitrogen-containing monomer include (meth)acrylamide, N-vinyl pyrrolidone, N-vinyl caprolactam, and the like.

The (meth)acrylic monomer having the crosslinkable functional group is 0.1 wt% or more, 0.5 wt% or more, or 1 wt% or more, based on 100 parts by weight of the monomer mixture, and 15 wt% or less, 10 wt% or less, or 5 wt% % or less. When the content of the (meth)acrylic monomer having the crosslinkable functional group satisfies the above range, better adhesion and durability may be obtained.

The content of the (meth)acrylic monomer having the crosslinkable functional group in 100% by weight of the total amount of the monomer mixture may be the same as the content of the repeating unit derived from the (meth)acrylic monomer having the crosslinkable functional group in 100% by weight of the total amount of the acrylic copolymer. there is.

Alkyl (meth) acrylate-based monomer

On the other hand, if the alkyl group included in the alkyl (meth) acrylate monomer becomes too large, the cohesive force of the pressure-sensitive adhesive may decrease, and it may be difficult to control the glass transition temperature (Tg) or the adhesiveness.

In this regard, as the alkyl (meth) acrylate monomer, one containing an alkyl group having 2 to 14 carbon atoms may be used.

Examples of such an 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, Isooctyl (meth)acrylate, isononyl (meth)acrylate, lauryl (meth)acrylate, tetradecyl (meth)acrylate, etc. are mentioned.

The content of the alkyl (meth) acrylate-based monomer is, in 100% by weight of the total amount of the monomer mixture, the monomer represented by Formula 1, the (meth)acrylic monomer including the alkoxy group, and (meth) including the cross-linkable functional group It may be an amount (remainder) excluding the content of the acrylic monomer.

For example, in 100 wt% of the total amount of the monomer mixture, the alkyl (meth)acrylate monomer is 75 wt% or more, 76 wt% or more, or 77 wt% or more, and 99 wt% or less, 95 wt% or less, or 93 wt% % or less. When the content of the alkyl (meth) acrylate-based monomer satisfies the above range, excellent adhesion and durability can be obtained.

The content of the alkyl (meth)acrylate-based monomer in 100% by weight of the total amount of the monomer mixture may be the same as the content of the repeating unit derived from the alkyl (meth)acrylate-based monomer in 100% by weight of the total amount of the acrylic copolymer.

Solvent and solid content of acrylic pressure-sensitive adhesive composition

The acrylic pressure-sensitive adhesive composition of the embodiment may further include a solvent.

The solvent may be used during the process of preparing the acrylic copolymer or added to adjust the viscosity after the acrylic copolymer is prepared.

In this regard, "solid content" in the present specification may be used in two broad contexts.

When the acrylic copolymer is prepared in the presence of the solvent to obtain an acrylic copolymer composition dispersed in the solvent, it may mean the solid content in the acrylic copolymer composition. This can be measured according to Experimental Example 1 to be described later.

In addition, when embodied as a pressure-sensitive adhesive composition (coating solution) by adding a solvent to adjust the viscosity after preparing the acrylic copolymer, it may mean the solid content in the pressure-sensitive adhesive composition (coating solution) to which the solvent is added. This can be measured according to Experimental Example 2 to be described later.

To distinguish the former from the latter, the former may be referred to as "solid content in the copolymer composition" or simply "solid content", and the latter as "solid content in the acrylic pressure-sensitive adhesive composition" or "coating solid content". .

Examples of the solvent include ethyl acetate, n-pentane, isopentane, neopentane, n-hexane, n-octane, n-heptane, methyl ethyl ketone, acetone, toluene, and the like.

The solvent may be included in an amount such that the solid content in the acrylic pressure-sensitive adhesive composition of the embodiment is 20% by weight or more, specifically 20 to 60% by weight, such as 20 to 30% by weight.

Viscosity of the acrylic pressure-sensitive adhesive composition

The acrylic pressure-sensitive adhesive composition of the embodiment has a low viscosity characteristic even when the solid content is high, so that excellent coating properties can be realized. Specifically, the acrylic pressure-sensitive adhesive composition of the embodiment has a low viscosity of 2,000 cP or less, specifically 300 to 2,000 cP, such as 500 cP to 2,000 cP, in a temperature range of 23 ° C. even when the solid content is 20 wt % or more. can

When the acrylic pressure-sensitive adhesive composition of one embodiment is used, it is possible to increase the solid content in the coating solution without deteriorating the coating property, thereby providing excellent productivity and precise control of thickness and the like.

other additives

The pressure-sensitive adhesive composition of one embodiment may further include other components such as a silane coupling agent, a crosslinking catalyst, a tackifying resin, an additive, and the like to control physical properties.

The silane coupling agent improves the 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. .

Specifically, the silane coupling agent is, γ-glycidoxypropyl triethoxy silane, γ-glycidoxypropyl trimethoxy silane, γ-glycidoxypropyl methyldiethoxy silane, γ-glycidoxypropyl trie Toxy silane, 3-mercaptopropyl trimethoxy silane, vinyltrimethoxysilane, vinyltriethoxy silane, γ-methacryloxypropyl trimethoxy silane, γ-methacryloxypropyl triethoxy silane, γ-amino Propyl trimethoxy silane, γ-aminopropyl triethoxy silane, 3-isocyanato propyl triethoxy silane, γ-acetoacetatepropyl trimethoxysilane, γ-acetoacetatepropyl triethoxy silane, β-sia and noacetyl trimethoxy silane, β-cyanoacetyl triethoxy silane, and acetoxyaceto trimethoxy silane, and one or a mixture of two or more of them may be used. Specifically, a silane-based coupling agent having an acetoacetate group or a β-cyanoacetyl group may be used.

In addition, the silane coupling agent may be a compound represented by the following formula (2).

[Formula 2]

(R _a ) _n Si(R _b ) _4-n

In Formula 2, R _a is a β-cyanoacetyl group, an acetoacetyl group, or an acetoacetylalkyl group, R _b is an alkoxy group, and n is an integer of 1 to 3. In this case, the alkyl group or alkoxy group included in Formula 2 may have 1 to 20, 1 to 16, 1 to 12, 1 to 8, or 1 to 4 carbon atoms, and may be a straight chain or branched chain.

Examples of the compound represented by Formula 2 include acetoacetylpropyl trimethoxysilane, acetoacetylpropyl triethoxy silane, beta-cyanoacetyl trimethoxy silane, or beta-cyanoacetyl triethoxy silane. However, the present invention is not limited thereto.

The silane-based coupling agent may be included in an amount of 0.01 parts by weight to 5 parts by weight, specifically 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 crosslinking catalyst is for accelerating curing (crosslinking) of the pressure-sensitive adhesive layer. When the pressure-sensitive adhesive composition includes a crosslinking catalyst, there is an advantage that it does not need to undergo a separate aging (aging) process after coating and drying the surface of the substrate.

Examples of the crosslinking catalyst include bis(tri-n-butyltin)oxide, bis(tri-n-butyltin)sulfate, di-n-butyldiphenyltin, and di-n-butyltinbis(acetyl). acetonate), di-n-butyltin bis(2-ethylhexanoate), di-n-butyltin dichloride, di-n-butyltin dilaurate, di-n-butyltin oxide, dimethyldiphenyltin, Dimethyltin dichloride, diphenyltin dichloride, diphenyltin oxide, hexa-n-butyltin, hexaphenyltin, tetra-n-butyltin, tetraphenyltin, tin (II) acetate, tin (II) acetylacetonate, Tin (II) chloride, tin (II) iodide, tin (II) oxalate, etc. may be used, but is not limited thereto.

The crosslinking catalyst may be included in an amount of 0.001 parts by weight to 0.5 parts by weight, specifically 0.001 parts by weight to 0.1 parts by weight based on 100 parts by weight of the acrylic copolymer. If the content of the crosslinking catalyst is less than 0.001 parts by weight, the curing accelerating effect is insignificant, and when it exceeds 0.5 parts by weight, there is a fear that durability may be lowered.

The acrylic pressure-sensitive adhesive composition of the embodiment 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 compatibility and/or the effect of improving cohesion may be reduced.

The acrylic pressure-sensitive adhesive composition of one embodiment is also one 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 in the range that does not affect the effect of the invention The above additives may be further included.

A method for producing an acrylic pressure-sensitive adhesive composition.

In another embodiment of the present invention,

0.01 to 1% by weight of the monomer represented by Formula 1, 5 to 30% by weight of a (meth)acrylic monomer containing an alkoxy group, 0.1 to 15% by weight of a (meth)acrylic monomer containing a crosslinkable functional group, and the remainder of the alkyl ( polymerizing a monomer mixture comprising a meth) acrylate monomer;

When the polymerization conversion of the monomer mixture reaches 50 to 60%, adding 0.1 to 0.5 parts by weight of a phenolic antioxidant based on 100 parts by weight of the monomer mixture; and

Polymerizing the monomer mixture in the presence of the phenolic antioxidant, comprising the step of preparing an acrylic copolymer having a polymerization conversion of 70% or more,

A method for producing an acrylic pressure-sensitive adhesive composition is provided.

As such, by controlling the type and mixing ratio of the monomer, the type of the antioxidant, the input amount, and the input time, the acrylic pressure-sensitive adhesive composition of the above-described embodiment can be prepared.

Hereinafter, the manufacturing method of the embodiment will be described in detail, but the description overlapping with the above will be omitted.

Monomer type and mixing ratio

Based on 100% by weight of the total amount, 0.01 to 1% by weight of the monomer represented by Formula 1, 5 to 30% by weight of a (meth)acrylic monomer including an alkoxy group, and 0.1 to 15% by weight of a (meth)acrylic monomer including a crosslinkable functional group %, and a monomer mixture comprising an alkyl (meth)acrylate monomer of the remainder may be polymerized to prepare a branched acrylic copolymer satisfying the repeating unit content of the above-described embodiment.

The content of each monomer in the monomer mixture is the same as described above, and detailed description thereof will be omitted.

phenolic antioxidants

As mentioned above, if you want to increase the weight average molecular weight of the branched acrylic copolymer, it is difficult to avoid gelation. For example, when an antioxidant is not added to the monomer mixture in the polymerization process, or an antioxidant including an amine group or a phosphite group is added, gelation may occur.

On the other hand, 0.1 to 0.5 parts by weight of the phenolic antioxidant based on 100 parts by weight of the monomer mixture (solid content) may be added when the polymerization conversion of the monomer mixture reaches 50 to 60%.

As such, when controlling the input amount and input timing of the phenol-based antioxidant, it is possible to implement a stable branched acrylic copolymer without gelation while having a high weight average molecular weight, and furthermore, it is possible to reach a final polymerization conversion rate of 70% or more.

The phenol-based antioxidant may include, among antioxidants generally known in the art, an antioxidant that includes phenol in a molecule, but does not include an amine group and a phosphite group.

Specifically, N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxyhydrocinnamamide) (N,N'-Hexamethylenebis(3,5-di-tert-butyl-4- hydroxyhydrocinnamamide)), 1,2-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoly) hydrazine (1,2-Bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoly) hydrazine) and the like, as it contains an amine group or a phosphite group, does not inhibit gelation during the polymerization process and makes it impossible to prepare an acrylic copolymer.

Examples of the antioxidant containing phenol in the molecule but not containing an amine group and a phosphite group include triethylene glycol-bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (triethylene glycol). -bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate), tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate ]Methane (Tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] methane), 　tris-(3,5-di-tert-butylhydroxybenzyl) isocyanurate ( tris-(3,5-di-tert-butylhydroxybenzyl) isocyanurate), thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate](Thiodiethylene bis[3- (3,5-di-tert-butyl-4-hydroxyphenyl)propionate]), 4,4'-butylidenebis (6-tert-3-methylphenol) (4,4'-butylidenebis(6-tert- 3-methylphenol)), octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propinate (Octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate) and 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene (1,3,5-Trimethyl-2,4,6 -tris(3,5-di-tert-butyl-4-hydroxybenzyl) benzene) containing one or more selected from the group consisting of may be used.

For example, the pressure-sensitive adhesive composition of one embodiment is triethylene glycol-bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate (triethylene glycol-bis-3-(3-tert- butyl-4-hydroxy-5-methylphenyl) propionate) or tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane (Tetrakis[methylene-3-( 3,5-di-tert-butyl-4-hydroxyphenyl)propionate] methane) may be further included.

Dosing amount and timing of phenolic antioxidant

As mentioned above, if you want to increase the weight average molecular weight of the branched acrylic copolymer, it is difficult to avoid gelation.

In this regard, in order to form a branched structure stably without gelation while realizing the weight average molecular weight of the acrylic copolymer at a high level of 1,150,000 to 2,000,000 g/mol, the monomer mixture (solid content) 100 weight 0.1 to 0.5 parts by weight of the phenolic antioxidant may be added when the polymerization conversion of the monomer mixture reaches 50 to 60%.

As such, when controlling the input amount and input time of the phenol-based antioxidant, it is possible to implement a stable branched acrylic copolymer without gelation while having a high weight average molecular weight, and further, it is possible to reach a final polymerization conversion rate of 70% or more.

However, when the phenol-based antioxidant having a polymerization conversion of the monomer mixture of less than 50% is added at the time, the polymerization conversion rate may fall short of the desired range, and productivity is reduced. On the other hand, when the phenolic antioxidant is added at the time when the polymerization conversion rate of the monomer mixture is more than 60%, gelation of the composition including the phenolic antioxidant occurs, and preparation of the acrylic copolymer may be impossible.

In consideration of such a tendency, the input time of the phenol-based antioxidant may be adjusted. For example, the input time of the phenolic antioxidant may be a time when the polymerization conversion rate of the monomer mixture is 50% or more, 51% or more, or 52% or more, and 60% or less, 59% or less, or 58% is reached. there is.

On the other hand, when the polymerization reaction is terminated, the polymerization conversion rate of the acrylic copolymer is 70% or more, 75% or more, or 80% or more, and 99% or less, 95% or less, or 90% by weight or less. can be

polymerization method

The acrylic copolymer may be prepared by mixing each of the above-described monomers to prepare a monomer mixture, and then polymerizing the same. In this case, 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.

Specifically, in the step of polymerizing the monomer mixture, a solution polymerization method may be used. More specifically, by adding an initiator, a molecular weight regulator, etc. in a state in which each monomer is uniformly mixed, the monomer mixture may be polymerized in a temperature range of 50 to 140 °C.

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 thereof may be used, but 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.

adhesive member

In another embodiment of the present invention, the substrate; and an adhesive layer formed on at least one surface on the substrate, and in particular, formed by the acrylic emulsion pressure-sensitive adhesive composition of one embodiment described above.

The acrylic pressure-sensitive adhesive composition of the above-described embodiment can implement low viscosity characteristics even under high solids content, and has excellent adhesion and re-peelability change rate, and the re-peelability of the adhesive member and durability in various environments by using it. It is excellent and is suitable for application to a polarizing plate of a display device.

The polarizing plate of one embodiment includes: a polarizing film; and an 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 described above.

The type of the polarizing film used in the embodiment 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 embodiment 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 that can extract 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 gelation degree 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 may be usually about 1,000 to 10,000, preferably about 1,500 to 5,000.

Polyvinyl alcohol-type resin as described above can be formed into a film, and it can be 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 It 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 may further include a protective film formed on one or both surfaces of the polarizer. The kind of protective film that can 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; polyethersulfone-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 to a normal thickness.

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

In the above embodiment, the process of forming the pressure-sensitive adhesive layer is preferably performed after sufficiently removing a bubble-inducing component such as a volatile component or a reaction residue 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 scattering body inside.

On the other hand, the method of curing the pressure-sensitive adhesive composition of the present invention during the manufacture of the polarizing plate is also not particularly limited, and may be carried out through a conventional curing method known in the art. For example, the curing may be performed by maintaining a temperature at which a crosslinking reaction can be induced between the crosslinkable functional group and the polyfunctional crosslinking agent in the pressure-sensitive adhesive composition applied through heating or the like.

The polarizing plate of the embodiment 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.

Here, the polarizing plate is exemplified, but the adhesive member of the embodiment is not limited to the use of the polarizing plate.

The adhesive member of the embodiment may exhibit little change over time of the adhesive layer, excellent durability even under high temperature or high temperature/high humidity conditions, and excellent rework properties.

In the adhesive member of the exemplary embodiment, a creep distance (Creep) change rate defined by Equation 1 below may be 5% or less.

[Equation 1]

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

In Equation 1 above,

T ₀ is the adhesive member of the measurement specimen was prepared by attaching the adhesive member to the glass substrate, stored at 23 ° C. and 50% RH for 4 days, and then the adhesive member of the measurement specimen was pulled for 1,000 seconds with a load of 1,000 g. is the push distance measured when,

T ₁ is the measurement specimen stored at 23 ℃, 50%RH conditions for 4 days, then further aged (aging) for 1 day at 80 ℃, the adhesive member of the measurement specimen for 1,000 seconds with a load of 1,000g This is the push distance measured when pulling.

The adhesive member of the embodiment may have an adhesive force change rate of 13% or less according to Equation 2 below.

[Equation 2]

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

In Equation 2 above,

B ₀ is after storing the adhesive member at 23 ℃, 50% RH conditions for 4 days, attaching the adhesive member to a glass substrate, storing at 23 ℃, 50% RH for 4 hours, then peeling rate 300mm/min , is the adhesive force measured when the adhesive member is pulled under the condition of a peeling angle of 180 degrees,

The B ₁ is after storing the adhesive member at 23 ℃, 50% RH conditions for 4 days, attaching the adhesive member to a glass substrate, storing at 23 ℃, 50% RH for 4 hours, and then at 80 ℃ 1 It is the adhesive force measured when the adhesive member is pulled under the conditions of a peeling rate of 300 mm/min and a peeling angle of 180 degrees after additional aging for one day.

The adhesive member of the embodiment may have a rate of change of a re-peel force according to Equation 3 below 10%.

[Equation 3]

Re-peel force change rate (%)= (C ₀ -C ₁ /C ₀ )×100

In Equation 3 above,

C ₀ is after storing the adhesive member at 23 ℃, 50%RH conditions for 1 day, attaching the adhesive member to a glass substrate, storing at 80 ℃ for 1 hour, 23 ℃, 50% RH for 1 hour After storage, the force required to completely separate the adhesive member when the adhesive member is pulled under the conditions of a peeling rate of 300 mm/min and a peeling angle of 180 degrees,

The C ₁ is after storing the adhesive member at 23° C. and 50% RH for 4 days, attaching the polarizing plate to a glass substrate, storing at 80° C. for 1 hour, and then at 23° C., 50% RH for 1 hour It is the force required to completely separate the adhesive member after storage, when the adhesive member is pulled under the conditions of a peeling rate of 300 mm/min and a peeling angle of 180 degrees.

display device

In another embodiment of the present invention, there is provided a display device including the adhesive member of the embodiment, for example, a polarizing plate.

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.

For example, the display apparatus may include F various passive matrix methods including a twisted neumatic (TN) type, a super twisted neumatic (STN) type, a ferroelectric (F) type, and a polymer dispersed LCD (PD) type; 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 device and a manufacturing method thereof are not particularly limited, and general configurations in this field may be employed without limitation.

Hereinafter, through specific examples of the invention, the operation and effect of the invention will be described in more detail. However, these embodiments are merely presented as an example of the invention, and the scope of the invention is not defined thereby.

<Example>

Example 1

(1) Preparation of acrylic copolymer composition

In a 3 L glass reactor equipped with a thermometer, stirrer, dropping funnel, nitrogen gas inlet tube and reflux condenser, 92.2 parts by weight of n-butyl acrylate (BA), ethoxyethoxyethyl acrylate (Viscoat #190, EEEA) ) 5.0 parts by weight, 2.5 parts by weight of 2-hydroxyethyl acrylate (HEA), and 0.3 parts by weight of allyl methacrylate (AMA) were added, and 60 parts by weight of ethyl acetate (EAc) was added as a solvent. The temperature inside the reactor was maintained at 25° C. while purging nitrogen gas for 60 minutes to remove oxygen.

Then, while continuously purging nitrogen gas for 60 minutes, the temperature inside the reactor was adjusted to 70 °C. After that, when the temperature inside the reactor is stabilized at 70 ° C., 0.13 parts by weight of n-dodecyl mercaptan (n-DDM) as a molecular weight regulator and azobis (2-4-dimethylvaleronitrile (V-65, manufacturer: Wako) as a polymerization initiator The reaction proceeded while additionally adding 0.15 parts by weight, where the molecular weight regulator was added in three divided doses until 1.5 hours elapsed from the time of initial introduction, and the polymerization initiator was added 5 hours after the minimum input while checking the degree of exotherm Until then, it was divided into 5 doses.

In the above reaction, after 1.5 hours from the time of the initial initiator input, the antioxidant triethylene glycol-bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (product name: SONGNOX 2450, manufacturer: SONGNOX) industry) 0.13 parts by weight was added. Then, after continuing the reaction for 5.5 hours (reaction for a total of 7 hours), the reaction was terminated and the acrylic copolymer composition of Example 1 was obtained.

Here, the polymerization conversion rate after 1.5 hours from the initial initiator input was 53.2%, and the final conversion rate after 7 hours was 85.2%.

For reference, the polymerization conversion rate was evaluated in Experimental Example 2 to be described later.

(2) Preparation of pressure-sensitive adhesive composition

Based on 100 parts by weight of the solid content in the acrylic copolymer composition of Example 1, 0.2 parts by weight of a polyfunctional curing agent (coronate L, manufactured by Nippon Polyurethane), 0.01 parts by weight of a crosslinking catalyst (DBTDL, Sigma-Aldrich), and a silane coupling agent ( 0.2 parts by weight of a beta-cyanoacetyl group-containing silane coupling agent (LG Chemical, M812) was mixed.

Aiming for the solid content (concentration) of 25.0% of the final pressure-sensitive adhesive composition (coating solution), an ethyl acetate solvent was added to dilute the mixture. Then, the pressure-sensitive adhesive composition of Example 1 was obtained by uniformly blending/mixing.

As a result of measuring the actual solid content and viscosity of the obtained pressure-sensitive adhesive composition of Example 1, the solid content was 25.1 wt%, and the viscosity was 1,770 cP (@ 23°C).

(3) Preparation of polarizing plate

The pressure-sensitive adhesive composition of Example 1 was applied to one surface of a polyethylene terephthalate film (release PET) having a thickness of 38 μm treated with silicone peeling treatment, and then dried at a temperature of 115° C. for 3 minutes to form a pressure-sensitive adhesive coating layer. Here, the application amount of the pressure-sensitive adhesive 　 composition was determined to be such that the thickness of the pressure-sensitive adhesive coating layer was formed to be 23 μm after drying.

Then, the adhesive coating layer was laminated on a conventional polarizing plate to prepare a polarizing plate including an adhesive layer.

Examples 2 to 7

the composition of the monomer mixture; the type, amount and timing of the antioxidant; each input amount of a polyfunctional crosslinking agent, a crosslinking catalyst, a silane coupling agent, and a molecular weight modifier; the type and dosage of the initiator; polymerization temperature; Factors such as target solid content (concentration) of the final pressure-sensitive adhesive composition (coating solution) are changed or controlled according to Table 1 below, and other matters are the same as in Example 1 above, and each acrylic copolymer of Examples 2 to 7 A composition, a pressure-sensitive adhesive composition, and a polarizing plate were prepared.

Comparative Examples 1 to 8

the composition of the monomer mixture; the type, amount and timing of the antioxidant; each input amount of a polyfunctional crosslinking agent, a crosslinking catalyst, a silane coupling agent, and a molecular weight modifier; the type and dosage of the initiator; polymerization temperature; Factors such as target solid content (concentration) of the final pressure-sensitive adhesive composition (coating solution) are changed or controlled according to Tables 2 and 3 below, and other matters are the same as in Example 1 above, and each acrylic type of Comparative Examples 1 to 8 A copolymer composition, a pressure-sensitive adhesive composition, and a polarizing plate were prepared.

Comparative Example 9

(1) Preparation of acrylic copolymer composition

In a 3 L glass reactor equipped with a thermometer, stirrer, dropping funnel, nitrogen gas inlet tube and reflux condenser, 87.5 parts by weight of n-butyl acrylate (BA), ethoxyethoxyethyl acrylate (Viscoat #190, EEEA) ) 10 parts by weight of a monomer mixture containing 2.5 parts by weight of 2-hydroxyethyl acrylate (HEA) was added, and 100 parts by weight of ethyl acetate (EAc) was added as a solvent, followed by purging with nitrogen gas for 60 minutes to remove oxygen. (purging) while maintaining the internal temperature of the reactor at 25 ℃. Then, while continuously purging nitrogen gas for 60 minutes, the temperature inside the reactor was adjusted to 64 °C. After that, when the reactor internal temperature is stabilized at 64 ° C., 0.015 parts by weight of n-dodecyl mercaptan (n-DDM) as a molecular weight regulator and 0.04 parts by weight of azobisisobutyronitrile (V-60, manufacturer: Wako) as a polymerization initiator are additionally added and the reaction proceeded.

In the reaction, after 3.0 hours from the time of the initial initiator input, 85 parts by weight of ethyl acetate (EAc) purged with nitrogen gas for 60 minutes was added for 60 minutes using a pump, and the reaction of the composition in progress The viscosity was lowered. In addition, the reaction was continued until 7.0 hours elapsed from the time of the initial initiator input, and then the reaction was terminated, and the acrylic copolymer composition of Comparative Example 9 was obtained. Here, the final conversion rate after 7 hours from the time of the initial initiator input was 86.4%.

(2) Preparation of pressure-sensitive adhesive composition and polarizing plate

While using the acrylic copolymer composition of Comparative Example 9 Change the target solid content (concentration) of the final pressure-sensitive adhesive composition (coating solution) according to Table 4 below, Other than that, in the same manner as in Example 1, the pressure-sensitive adhesive compositions and polarizing plates of Comparative Examples 2 to 9 were prepared.

Comparative Examples 10 to 12

the composition of the monomer mixture; the type, amount and timing of the antioxidant; each input amount of a polyfunctional crosslinking agent, a crosslinking catalyst, a silane coupling agent, and a molecular weight modifier; the type and dosage of the initiator; polymerization temperature; and a target solid content (concentration) of the final pressure-sensitive adhesive composition (coating solution); the timing and amount of additional addition of solvent; Factors, such as, were changed or controlled according to Table 4 below, and other matters were the same as in Comparative Example 9, to prepare each acrylic copolymer composition, pressure-sensitive adhesive composition and polarizing plate of Comparative Examples 10 to 12.

For reference, each material listed in Tables 1 to 4 is as follows.

1) Monomer

BA: n-butyl acrylate

2-MTA: 2-methoxyethyl acrylate

Viscoat190: ethoxyethoxyethyl acrylate (Viscoat#190, EEEA), HEA is hydroxyethyl acrylate

HEA: 2-hydroxyethyl acrylate

AMA: Allyl Methacrylate

2) antioxidants

SONGNOX 2450, Songnox 1010 , Songnox 5057 , and Songnox PQ are product names, respectively, and specific material names and manufacturers are as follows.

SONGNOX 2450: triethylene glycol-bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (Manufacturer: Songwon Industrial)

Songnox 1010 : Tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] methane (Manufacturer: Songwon Industrial)

Songnox 5057 : Mixture of octylated diphenylamine and butylated diphenylamine (Manufacturer: Songwon Industrial)

Songnox PQ:　tetrakis(2,4-di-tert-butylphenyl)[1,1-biphenyl]-4,4'-diylbisphosphonite (Manufacturer: Songwon Industrial)

3) Other Additives

Multifunctional crosslinking agent: coronate L (manufactured by Nippon Polyurethane)

Crosslinking catalyst: DBTDL (manufacturer: Sigma-Aldrich)

Silane coupling agent: Silane coupling agent containing beta-cyanoacetyl group (Product name: M812, Manufacturer: LG Chem)

Polymerization initiator: azobis(2-4-dimethylvaleronitrile (V-65, manufacturer: Wako) or azobisisobutyronitrile (V-60, manufacturer: Wako)

Molecular weight modifier: n-dodecylmercaptan (n-DDM)

EAc: ethyl acetate

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 acrylic
copolymer
(solid content) Furtherance
(parts by weight) BA 92.20 92.20 87.20 87.25 87.30 77.25 77.25 2-MTA - 5.0 10.0 10.0 10.0 20.0 20.0 Viscoat190 5.0 - - - - - - HEA 2.5 2.5 2.5 2.5 2.5 2.5 2.5 AMA 0.30 0.30 0.30 0.25 0.2 0.25 0.25 total amount 100 100 100 100 100 100 100 Oxidation
inhibitor division Phenolic product Songnox
2450 Songnox
2450 Songnox
2450 Songnox
2450 Songnox
2450 Songnox
2450 Songnox
1010 Input amount (parts by weight) 0.13 0.13 0.13 0.26 0.46 0.46 0.46 input point
(@Polymerization conversion (%)) 53.2 56.3 55.6 55.3 55.4 55.4 52.6 multifunctionality
crosslinking agent Input amount (parts by weight) 0.2 0.2 0.2 0.2 0.2 0.2 0.2 bridge
catalyst 0.01 0.01 0.01 0.01 0.01 0.01 0.01 silane
coupling agent 0.2 0.2 0.2 0.2 0.2 0.2 0.2 initiator product V-65 V-65 V-65 V-65 V-65 V-65 V-65 Input amount (parts by weight) 0.15 0.15 0.15 0.15 0.15 0.15 0.15 Molecular Weight
modifier Input amount (parts by weight) 0.13 0.13 0.13 0.094 0.072 0.072 0.072 Polymerization temperature (℃) 70 70 70 70 70 70 70 Target solids content (wt%) 25.0 25.0 25.0 20.0 20.0 20.0 20.0

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 acrylic
copolymer
(solid content) Furtherance
(parts by weight) BA 87.20 97.25 94.20 87.20 2-MTA 10.0 0.0 - 10.0 Viscoat190 - - 3.0 - HEA 2.5 2.5 2.5 2.5 AMA 0.30 0.25 0.30 0.30 total amount 100 100 100 100 Oxidation
inhibitor division Phenolic product Songnox
2450 Songnox
2450 Songnox
2450 Songnox
2450 content (wt%) 0.18 0.26 0.13 0.13 input point
(@Polymerization conversion (%)) 55.4 55.6 55.4 64.3 Multifunctional crosslinking agent Input amount (parts by weight) 0.2 0.2 0.2 - bridge
catalyst 0.01 0.01 0.01 - silane
coupling agent 0.2 0.2 0.2 - initiator product V-65 V-65 V-65 V-65 Input amount (parts by weight) 0.15 0.15 0.15 0.15 molecular weight modifier Input amount (parts by weight) 0.145 0.094 0.13 0.13 Polymerization temperature (℃) 70 70 70 70 Target solids content (wt%) 27.5 20.0 25.0 -

Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 acrylic
copolymer
(solid content) Furtherance
(parts by weight) BA 87.20 87.20 87.20 87.30 2-MTA 10.0 10.0 10.0 10.0 Viscoat190 - - - - HEA 2.5 2.5 2.5 2.5 AMA 0.30 0.30 0.30 0.20 total amount 100 100 100 100 antioxidant division - Aminic Phosphite Phenolic product Songnox
5057 Songnox
PQ Songnox
2450 content (wt%) - 0.13 0.13 0.7 input point
(@Polymerization conversion (%)) - 55.7 54.9 56.8 Multifunctional crosslinking agent Input amount (parts by weight) - - - 0.2 bridge
catalyst - - - 0.01 silane
coupling agent - - - 0.2 initiator product V-65 V-65 V-65 V-65 Input amount (parts by weight) 0.15 0.15 0.15 0.15 molecular weight modifier Input amount (parts by weight) 0.13 0.13 0.13 0.072 Polymerization temperature (℃) 70 70 70 70 Target solids content (wt%) - - - 24.0

Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 acrylic
copolymer
(solid content) Furtherance
(parts by weight) BA 87.50 87.50 87.50 87.50 2-MTA 10.0 10.0 10.0 10.0 Viscoat190 - - - - HEA 2.5 2.5 2.5 2.5 AMA - - - - total amount 100 100 100 100 Oxidation
inhibitor division - - - - product - - - - Content (wt%) - - - - input point
(@Polymerization conversion (%)) - - - - Multifunctional crosslinking agent Input amount (parts by weight) 0.2 0.2 0.2 0.2 bridge
catalyst 0.01 0.01 0.01 0.01 silane
coupling agent 0.2 0.2 0.2 0.2 initiator product V-60 V-60 V-60 V-60 Input amount (parts by weight) 0.04 0.04 0.04 0.04 molecular weight modifier Input amount (parts by weight) 0.015 0.011 0.006 0.006 Polymerization temperature (℃) 64 ℃ 64 ℃ 64 ℃ 64 ℃ Target solids content (wt%) 20.0 20.0 20.0 15.5 Diluted EAc (parts by weight) 85 85 85 85 dilution time 3.0 hours 2.5 hours 2.0 hours 2.0 hours

<Experimental example>

Experimental Example 1: Measurement of polymer structure, weight average molecular weight and polymerization conversion of acrylic copolymer

For each acrylic copolymer (solid content) of Examples and Comparative Examples, the polymerization conversion rate and weight average molecular weight of the polymer structure were evaluated and shown in Tables 5 to 7.

(1) Polymer structure: First, having the same kind of alkyl (meth)acrylic monomer and crosslinkable functional group as used in the acrylic copolymer to be evaluated for the polymer structure (hereinafter referred to as the 'copolymer to be evaluated') (meth) ) by mixing an acrylic monomer to prepare a monomer mixture. At this time, the content of the (meth)acrylic monomer (HEA) having a crosslinkable functional group in the monomer mixture was made equal to the content of the (meth)acrylic monomer (HEA) having a crosslinkable functional group in the evaluation target copolymer. 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, an ethyl acetate solvent was added to each of the reference copolymer and the copolymer to be evaluated to adjust the solid content concentration to 20% by weight, and then the viscosity was measured. If the viscosity of the evaluation target copolymer measured as described above has a viscosity that is 30% by weight 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 did

(2) Polymerization conversion (unit: %): The polymerization conversion rate was measured as follows.

First, measure the weight (A) of an aluminum dish, and then, a sample that requires calculation of the polymerization conversion rate (a sample of acrylic copolymer taken immediately before adding antioxidant or a sample of acrylic copolymer after completion of the final reaction) 0.3 to 0.5 It was collected in an amount of about g (weight of the sample before drying: S) and placed in a weighed aluminum dish. At this time, measure the weight B (A+S) of the sample before drying including the aluminum dish.

Then, a very small amount of an ethyl acetate solution (a polymerization inhibitor concentration of 0.5% by weight) in which a polymerization inhibitor (hydroquinone) is dissolved is added to the pressure-sensitive adhesive composition using a pipette, and the solvent is removed by drying it in an oven at 150° C. for about 30 minutes. removed.

Thereafter, the dried sample was cooled at room temperature for about 15 to 30 minutes, and after drying including the aluminum dish weight A, the weight including the weight C of the sample was measured, and the solid content (concentration) was measured according to Equation 4 below.

[Formula 4] Solid content (% by weight) = {(C-A)/(B-A)}×100

In Equation 4, A is the weight of the aluminum dish (unit: g), C is the weight of the sample after drying including the weight A of the aluminum dish (unit: g), and B is the weight of the sample before drying including the weight A of the aluminum dish Weight (unit: g).

[Equation 5] Polymerization conversion (%) = Solid content concentration/reaction concentration of Equation 4*100

In Equation 5, the reaction concentration is the monomer weight concentration with respect to the weight of the monomer and solvent (unit g) added up to the time of sample collection.

(3) Weight average molecular weight: It was measured under the following conditions using GPC. The standard polystyrene of Agilent system was used to prepare the calibration curve, and the measurement results were converted.

<Measurement conditions>

Meter: Agilent GPC (Agulent 1200 series, USA)

Column: 2 PL Mixed B connections

Column temperature: 40°C

Eluent: Tetrohydrofuran

Flow rate: 1.0 mL/min

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

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 polymer structure branched branched branched branched branched branched branched Polymerization conversion (%) 85.2 85.8 85.1 84.9 82.2 81.3 81.2 Mw (g/mol) 1,240k 1,250k 1,230k 1,370k 1,580k 1,560k 1,570k

comparative example
One comparative example
2 comparative example
3 comparative example
4 comparative example
5 comparative example
6 comparative example
7 comparative example
8 polymer structure branched branched branched Gelation Gelation Gelation Gelation branched Polymerization conversion (%) 84.9 84.4 85.1 Measure
impossible Measure
impossible Measure
impossible Measure
impossible 64.6 Mw (g/mol) 1,120k 1,380k 1,230k 1,310k

Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 polymer structure linear linear linear linear Polymerization conversion (%) 86.4 87.9 80.2 80.2 Mw (g/mol) 1,220k 1,350k 1,520k 1,520k

Experimental Example 2: Evaluation of coating viscosity and coating properties of the pressure-sensitive adhesive composition

For each pressure-sensitive adhesive composition of Examples and Comparative Examples, the solid content, coating viscosity and coating properties were evaluated and shown in Tables 8 to 10.

(1) Solids content in the pressure-sensitive adhesive composition (unit: wt%): The coating solids content (coating solids) in the pressure-sensitive adhesive composition was measured as follows.

First, the weight (A) of an aluminum dish is measured, and then the pressure-sensitive adhesive composition prepared in Examples or Comparative Examples is collected in an amount of about 0.3 to 0.5 g (weight of the sample before drying: S) and the weight is It was placed in a measured aluminum dish. At this time, the weight B (A+S) of the sample before drying including the aluminum dish is measured. Then, a very small amount of an ethyl acetate solution (a polymerization inhibitor concentration of 0.5 wt%) in which a polymerization inhibitor (hydroquinone) is dissolved is added to the pressure-sensitive adhesive composition using a pipette, and the solvent is removed by drying it in an oven at 150°C for about 30 minutes. removed. Thereafter, the dried sample was cooled at room temperature for about 15 to 30 minutes, and after drying including the aluminum dish weight A, the weight including the weight C of the sample was measured, and the coating solid content (concentration) was measured according to Equation 6 below. .

[Formula 6]: Coating solid content (% by weight) = {(C-A)/(B-A)}×100

In Equation 6, A is the weight (unit: g) of the aluminum dish, C is the weight of the sample after drying including the weight A of the aluminum dish (unit: g), and B is the weight of the sample before drying including the weight A of the aluminum dish Weight (unit: g).

(2) Viscosity of the pressure-sensitive adhesive composition (unit: cP): The viscosity of the pressure-sensitive adhesive composition was evaluated according to the following procedure using a Brookfield digital viscometer (RV DV2T).

Put about 220 mL of the adhesive agent composition in a 250 mL PE bottle, close the lid to prevent the solvent from volatilizing, 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 sealing and lid, the spindle was placed at an angle to prevent bubbles from forming in the 　 adhesive 　 composition, and the spindle was connected to a viscometer, and the liquid level of the 　 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%).

(3) Coatability of the pressure-sensitive adhesive composition: The coatability was evaluated according to the following criteria by visually observing the state of the coating layer when the pressure-sensitive adhesive composition was coated on a polyethylene terephthalate film:

<Coatability Evaluation Criteria>

O: Bubbles, streaks, etc. are not visually confirmed in the coating layer.

X: Bubbles and/or streaks were visually confirmed in the coating layer

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 in the pressure-sensitive adhesive composition
Solid content (wt%) 25.1 24.7 25.3 20.1 20.2 20.1 20.2 Coating Viscosity (cP)@23℃ 1,770 1,810 1,760 1,610 1970 1,820 1,910 coatability ○ ○ ○ ○ ○ ○ ○

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 in the pressure-sensitive adhesive composition
Solid content (wt%) 27.5 20.2 25.4 Measure
impossible Measure
impossible Measure
impossible Measure
impossible 24.3 Coating Viscosity (cP)@23℃ 1,730 1,700 1,810 1,910 coatability ○ ○ ○ ○

Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 in the pressure-sensitive adhesive composition
Solid content (wt%) 20.1 20.0 20.2 15.8 Coating Viscosity (cP)@23℃ 4,120 6,230 10,150 1990 coatability X X X ○

Experimental Example 3: Evaluation of pushing distance, adhesive force, re-peelability and re-peelability and durability of the polarizing plate

For the polarizing plates prepared by using each of the pressure-sensitive adhesive compositions of Examples and Comparative Examples, the sliding distance, adhesive force, re-peelability and re-peelability and durability were evaluated and shown in Tables 11 to 13.

(1) Creep distance (Unit: ㎛)

Each of the polarizing plates of Examples and Comparative Examples was cut to have a width of 10 mm and a length of 10 mm to prepare a specimen. 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 at constant temperature and constant humidity conditions (23° C., 50% RH), and then, using TA equipment (Texture Analyzer, Stable Microsystems Co., UK), the pushing distance T ₀ was measured. At this time, the creep distance (Creep) was measured as the distance (unit: μm) pushed by the polarizing plate 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 at constant temperature and constant humidity conditions (23 ° C., 50% RH), and then further aged at 80 ° C. for 1 day, and then aged in the same manner, and then the rolling distance T ₁ was measured. did

Then, the sliding distance T _O and T ₁ were substituted into Equation 1 below to calculate the rate of change of the sliding distance.

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

(2) Adhesion

After each of the polarizing plates of Examples and Comparative Examples were stored at constant temperature and constant humidity (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 for 4 hours at constant temperature and constant humidity conditions (23° C., 50% RH), the polarizing plate is completely removed from the glass substrate by pulling the polarizing plate under the conditions of a peeling rate of 300 mm/min and a peeling angle of 180 degrees. By measuring the force required to separate, the adhesive force B ₀ (unit: gf/25 mm) was measured.

In addition, after the specimen for measurement was stored for 4 hours at constant temperature and constant humidity conditions (23° C., 50% RH), and then further aged at 80° C. for 1 day, adhesive strength B ₁ was measured in the same manner.

Then, the adhesive force B ₀ and B ₁ were substituted into Equation 2 below to calculate the rate of change of the adhesive force.

[Equation 2] Adhesive force change rate (%) = (B ₀ -B ₁ /B ₀ )×100

(3) Re-peel force (unit: gf/25mm) and re-peelability:

Each of the polarizing plates of Examples and Comparative Examples were stored for 1 day and 4 days, respectively, under constant temperature and constant humidity conditions (23° C., 50% R.H.), and then cut to have a width of 25 mm and a length of 100 mm to prepare a specimen. Then, the release PET film attached to the adhesive layer was peeled off, and a polarizing plate was attached to an alkali-free glass using a 2 kg roller according to JIS Z 0237 to prepare a measurement specimen.

Then, the specimen for measurement was stored at 80° C. for 1 hour, and then stored at constant temperature and humidity conditions (23° C., 50% R.H.) for 1 hour. Then, the force required to completely separate the polarizing plate from the glass substrate is measured by pulling the polarizing plate under the conditions of a peeling rate of 300 mm/min and a peeling angle of 180 degrees using TA equipment (Texture Analyzer, manufactured by Stable Microsystems, UK). to measure the re-peel force (unit: gf/25mm).

In addition, re-peelability was evaluated based on the following criteria after re-peelling.

<Evaluation criteria>

○: When the re-peel force is 1,500 gf/25 mm or less, and there is no adhesive layer remaining on the glass substrate after re-peelling

△: When the re-peel force exceeds 1,500 gf/25 mm and 2,500 gf/25 mm or less, or when the adhesive layer residue is confirmed on the glass substrate after re-peeling, and the residue area is 5% or less

×: When the re-peel force exceeds 3,000 gf/25 mm, or when the adhesive layer residue is confirmed on the glass substrate after re-peeling, and the residue area exceeds 5%

(4) Durability evaluation

Each of the polarizing plates of Examples and Comparative Examples was cut to a size of 180 mm × 250 mm (length × width) to prepare a sample, and the sample was attached to a 19-inch commercial panel using a laminator. Thereafter, the panel was compressed 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 measurement specimen.

Heat resistance durability was evaluated by leaving the prepared specimen at a temperature of 80° C. for 500 hours, and then observing whether bubbles or peeling occurred.

The heat-and-moisture resistance was evaluated by leaving the prepared 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.

Moist heat resistance and room temperature low-humidity durability, the specimen for which the heat-and-moisture resistance was evaluated was left for 500 hours at a temperature of 25° C. and a relative humidity of 25% R.H.

<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 Example 3 Example 4 Example 5 Example 6 Example 7 Creep
[um] 1 day later 383 389 386 371 340 339 341 4 days later 366 371 372 360 332 330 332 adhesiveness
[gf/25mm] 1 day later 568 576 580 540 455 450 453 4 days later 497 503 510 483 415 410 412 re-peelability
[gf/25mm] 1 day later 1,510 1,530 1,560 1,350 960 964 967 4 days later 1,370 1,380 1,410 1,230 890 897 898 re-peelability 1 day later ○ ○ ○ ○ ○ ○ ○ 4 days later ○ ○ ○ ○ ○ ○ ○ durability heat resistance ○ ○ ○ ○ ○ ○ ○ moisture heat resistance ○ ○ ○ ○ ○ ○ ○ Heat resistance + room temperature low humidity ○ ○ ○ ○ ○ ○ ○

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Creep
[um] 1 day later 395 391 405 Measure
impossible Measure
impossible Measure
impossible Measure
impossible 391 4 days later 376 358 370 375 adhesiveness
[gf/25mm] 1 day later 600 653 674 Measure
impossible Measure
impossible Measure
impossible Measure
impossible 590 4 days later 520 490 500 515 re-peelability
[gf/25mm] 1 day later 1680 2460 2560 Measure
impossible Measure
impossible Measure
impossible Measure
impossible 1,620 4 days later 1490 2060 2120 1,450 re-peelability 1 day later ○ X X evaluation
impossible evaluation
impossible evaluation
impossible Measure
impossible ○ 4 days later ○ △ △ ○ durability heat resistance ○ ○ ○ evaluation
impossible evaluation
impossible evaluation
impossible Measure
impossible △ moisture heat resistance ○ ○ ○ ○ Heat resistance + room temperature low humidity △ ○ ○ X

Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 Creep
[um] 1 day later not measurable not measurable not measurable 385 4 days later 341 adhesiveness
[gf/25mm] 1 day later not measurable not measurable not measurable 680 4 days later 504 re-peel power
[gf/25mm] 1 day later not measurable not measurable not measurable 2,610 4 days later 2,080 re-peelability 1 day later not rated not rated not rated X 4 days later △ durability heat resistance not rated not rated not rated ○ moisture heat resistance ○ moisture heat resistance
+ room temperature and low humidity ○

Comprehensive evaluation

When the above Tables 5 to 13 are summarized, compared to the pressure-sensitive adhesive composition of Comparative Examples 1 to 12, the superiority of the pressure-sensitive adhesive composition of Examples 1 to 7 is confirmed.

Specifically, the pressure-sensitive adhesive compositions of Examples 1 to 7 exhibited viscosity characteristics of 2,000 cP or less even when the solid content was as high as 20% by weight or more, and excellent stability over time due to low rates of change in pushing distance, adhesive force, and re-peelability can be known

In addition, the re-peelability of the pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive composition of Examples 1 to 7 was excellent, and durability in high temperature, high temperature/high humidity and room temperature and low humidity environments was also excellent.

This is evaluated as the effect of controlling the type and compounding ratio of the repeating unit (monomer) constituting the acrylic copolymer, the structure, molecular weight, and polymerization conversion of the acrylic copolymer within the ranges of the embodiment.

On the other hand, the pressure-sensitive adhesive composition of Comparative Examples 1 to 3 and 8, despite including the branched acrylic copolymer, compared to Examples 1 to 7, the acrylic pressure-sensitive adhesive composition and the physical properties of the polarizing plate manufactured using the same decreased has happened

Specifically, the pressure-sensitive adhesive composition of Comparative Example 1, the molecular weight of the acrylic copolymer does not satisfy the range specified in the embodiment, it is evaluated that the durability of the polarizing plate is reduced.

In addition, in the pressure-sensitive adhesive compositions of Comparative Examples 2 and 3, the type and compounding ratio of the repeating unit (monomer) do not satisfy the ranges specified in the one embodiment, so that the acrylic pressure-sensitive adhesive composition changes over time, and the re-peelability of the polarizing plate This is considered to be lowered.

In the pressure-sensitive adhesive composition of Comparative Example 8, the content of the antioxidant does not satisfy the range specified in the embodiment, a copolymer having a low polymerization conversion rate is prepared, and thus, it is evaluated that the durability of the polarizing plate is reduced.

On the other hand, in the pressure-sensitive adhesive compositions of Comparative Examples 4 to 7, the acrylic copolymer itself could not be produced under the influence of the antioxidant.

Specifically, when preparing the pressure-sensitive adhesive composition of Comparative Example 4, the antioxidant was added past the time specified in the embodiment, and gelation proceeded accordingly, so that the co-acrylic polymer could not be prepared.

In addition, when preparing the pressure-sensitive adhesive composition of Comparative Example 5, antioxidants were not used at all, and even in this case, gelation proceeded, so that the acrylic copolymer could not be prepared.

When the pressure-sensitive adhesive composition of Comparative Examples 6 and 7 was prepared, the type of antioxidant was changed to an amine-based (Comparative Example 6) and a phosphite-based (Comparative Example 7), respectively, and in these cases, gelation proceeded to prepare the acrylic copolymer could not be manufactured.

On the other hand, the pressure-sensitive adhesive composition of Comparative Examples 9 to 12, due to the influence of the structure of the acrylic copolymer, compared to Examples 1 to 7, the acrylic pressure-sensitive adhesive composition and the physical properties of the polarizing plate prepared using the same decreased.

Specifically, the pressure-sensitive adhesive compositions of Comparative Examples 9 to 12 include a linear acrylic copolymer formed from a monomer composition that does not include the monomer (AMA) represented by Formula 1 above. Such a linear acrylic copolymer can be synthesized without the input of an antioxidant, but the viscosity of the pressure-sensitive adhesive composition is excessively increased to inhibit coating properties and productivity, cause changes over time, and weaken the re-peelability of the polarizing plate.

Based on the above results, in the acrylic pressure-sensitive adhesive composition of one embodiment, the type and compounding ratio of the repeating unit constituting the acrylic copolymer, the structure of the acrylic copolymer, the molecular weight, and the polymerization conversion are controlled. As a result, low viscosity characteristics even under high solids content It is evaluated that it is suitable for application to a polarizing plate of a display device because it has excellent adhesion and re-peelability change rate, as well as excellent re-peelability and durability in various environments using this.

In addition, it is evaluated that the acrylic pressure-sensitive adhesive composition of the embodiment can be efficiently prepared by controlling the compounding ratio of the monomer, the type of antioxidant, the input amount, and the input time.

Claims (18)

Based on 100% by weight of the total amount, 0.01 to 1% by weight of a first repeating unit derived from a monomer represented by the following Chemical Formula 1, and a (meth)acrylic monomer-derived second repeating unit including an alkoxy group 5 to 30% by weight, 0.1 to 15% by weight of a third repeating unit derived from a (meth)acrylic monomer containing a crosslinkable functional group, and the remainder of an acrylic copolymer comprising a fourth repeating unit derived from an alkyl (meth)acrylate monomer; including,
The acrylic copolymer is
polymerization conversion is 70% or more,
The weight average molecular weight is 1,150,000 to 2,000,000 g/mol,
which has a branched polymer structure,
Acrylic pressure-sensitive adhesive composition:
[Formula 1]
R ¹ -CH=CR ² -(C=O)-OXY
In Formula 1,
R ¹ is hydrogen, a C _1-6 alkyl group or a C _1-6 alkenyl group,
R ² is hydrogen or a C _1-10 alkyl group,
X is a single bond; Or, C _1-10 alkylene group, C _2-10 alkenylene group, ether, ester, or a combination of two or more thereof,
Y is a vinyl group, an allyl group, or a C _3-10 cycloalkenyl group.
The method of claim 1,
The acrylic copolymer is
The polymerization conversion is 80 to 90%,
Acrylic adhesive composition.
The method of claim 1,
The monomer represented by the formula (1) is,
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 2-allyloxyethyl methacrylate, 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) selected from the group consisting of more than one
Acrylic adhesive composition.
The method of claim 1,
The (meth)acrylic monomer containing the alkoxy group,
Alkoxy ethylene glycol (meth) acrylic acid ester, alkoxy diethylene glycol (meth) acrylic acid ester, alkoxy triethylene glycol (meth) acrylic acid ester, alkoxy tetraethylene glycol (meth) acrylic acid ester, alkoxy propylene glycol (meth) acrylic acid ester, alkoxy tri At least one selected from the group consisting of propylene glycol (meth) acrylic acid ester, and alkoxy tetrapropylene glycol (meth) acrylic acid ester;
Acrylic adhesive composition.
The method of claim 1,
The (meth)acrylic monomer including the crosslinkable functional group,
2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl ( a hydroxyl group-containing monomer group consisting of meth) acrylate, 2-hydroxyethylene glycol (meth) acrylate and 2-hydroxypropylene glycol (meth) acrylate;
(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 a carboxyl group-containing monomer group consisting of maleic anhydride; and
(meth) at least one selected from the group of nitrogen-containing monomers consisting of acrylamide, N-vinyl pyrrolidone and N-vinyl caprolactam;
Acrylic adhesive composition.
According to claim 1,
The alkyl (meth) acrylate monomer,
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, isooctyl (meth) acrylate, isononyl (meth) At least one selected from the group consisting of acrylate, lauryl (meth) acrylate and tetradecyl (meth) acrylate,
Acrylic adhesive composition.
According to claim 1,
The acrylic pressure-sensitive adhesive composition,
At least one solvent selected from the group consisting of ethyl acetate, n-pentane, isopentane, neopentane, n-hexane, n-octane, n-heptane, methyl ethyl ketone, acetone and toluene;
Acrylic adhesive composition.
According to claim 1,
The solid content in the acrylic pressure-sensitive adhesive composition is,
20% by weight or more,
Acrylic adhesive composition.
According to claim 1,
The acrylic pressure-sensitive adhesive composition,
which has a viscosity of 500 to 2000 cP at 23 °C,
Acrylic adhesive composition.
0.01 to 1% by weight of a monomer represented by the following formula (1), 5 to 30% by weight of a (meth)acrylic monomer including an alkoxy group, 0.1 to 15% by weight of a (meth)acrylic monomer including a crosslinkable functional group, and the remainder of the alkyl ( polymerizing a monomer mixture comprising a meth)acrylate monomer;
When the polymerization conversion of the monomer mixture reaches 50 to 60%, adding 0.1 to 0.5 parts by weight of a phenolic antioxidant based on 100 parts by weight of the monomer mixture; and
Polymerizing the monomer mixture in the presence of the phenolic antioxidant, comprising the step of preparing an acrylic copolymer having a polymerization conversion of 70% or more,
Method for producing an acrylic pressure-sensitive adhesive composition:
[Formula 1]
R ¹ -CH=CR ² -(C=O)-OXY
In Formula 1,
R ¹ is hydrogen, a C _1-6 alkyl group or a C _1-6 alkenyl group,
R ² is hydrogen or a C _1-10 alkyl group,
X is a single bond; Or, C _1-10 alkylene group, C _2-10 alkenylene group, ether, ester, or a combination of two or more thereof,
Y is a vinyl group, an allyl group, or a C _3-10 cycloalkenyl group.
11. The method of claim 10,
The phenolic antioxidant is
Triethylene glycol-bis-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (triethylene glycol-bis-3-(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate), tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane (Tetrakis[methylene-3-(3,5-di-tert-butyl- 4-hydroxyphenyl)propionate] methane), tris-(3,5-di-tert-butylhydroxybenzyl) isocyanurate (tris-(3,5-di-tert-butylhydroxybenzyl) isocyanurate), thiodiethylene bis [3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate](Thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]), 4 ,4'-butylidenebis (6-tert-3-methylphenol) (4,4'-butylidenebis(6-tert-3-methylphenol)), octadecyl-3- (3,5-di-tert- Butyl-4-hydroxyphenyl)propionate (Octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) and 1,3,5-trimethyl-2,4,6-tris(3 ,5-di-tert-butyl-4-hydroxybenzyl) to benzene (1,3,5-Trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl) benzene) Containing one or more selected from the group consisting of,
A method for producing an acrylic pressure-sensitive adhesive composition.
11. The method of claim 10,
The input amount of the phenolic antioxidant is,
Based on 100 parts by weight of the acrylic copolymer, 0.01 to 0.6 parts by weight,
A method for producing an acrylic pressure-sensitive adhesive composition.
write; and
A pressure-sensitive adhesive layer formed on at least one surface on the substrate,
The pressure-sensitive adhesive layer is formed by the acrylic pressure-sensitive adhesive composition according to claim 1,
no adhesive.
14. The method of claim 13,
The adhesive member is
That the creep distance (Creep) change rate according to the following formula 1 is 5% or less,
Adhesive member:
[Equation 1]
Push distance change rate (%)= (T ₀ -T ₁ /T ₀ )×100
In Equation 1 above,
T ₀ is the adhesive member of the measurement specimen was prepared by attaching the adhesive member to the glass substrate, stored at 23 ° C. and 50% RH for 4 days, and then the adhesive member of the measurement specimen was pulled for 1,000 seconds with a load of 1,000 g. is the push distance measured when,
T ₁ is the measurement specimen stored at 23 ℃, 50%RH conditions for 4 days, then further aged (aging) for 1 day at 80 ℃, the adhesive member of the measurement specimen for 1,000 seconds with a load of 1,000g This is the push distance measured when pulling.
14. The method of claim 13,
The adhesive member is
The rate of change of adhesive force according to the following formula 2 is 13% or less,
Adhesive member:
[Equation 2]
Adhesion change rate (%)= (B ₀ -B ₁ /B ₀ )×100
In Equation 2 above,
B ₀ is after storing the adhesive member at 23 ℃, 50% RH conditions for 4 days, attaching the adhesive member to a glass substrate, storing at 23 ℃, 50% RH for 4 hours, then peeling rate 300mm/min , is the adhesive force measured when the adhesive member is pulled under the condition of a peeling angle of 180 degrees,
The B ₁ is after storing the adhesive member at 23 ℃, 50% RH conditions for 4 days, attaching the adhesive member to a glass substrate, storing at 23 ℃, 50% RH for 4 hours, and then at 80 ℃ 1 It is the adhesive force measured when the adhesive member is pulled under the conditions of a peeling rate of 300 mm/min and a peeling angle of 180 degrees after additional aging for one day.
14. The method of claim 13,
The adhesive member is
The change rate of the re-peel force according to the following formula 3 is 10% or less,
Adhesive member:
[Equation 3]
Re-peel force change rate (%)= (C ₀ -C ₁ /C ₀ )×100
In Equation 3 above,
C ₀ is after storing the adhesive member at 23 ℃, 50%RH conditions for 1 day, attaching the adhesive member to a glass substrate, storing at 80 ℃ for 1 hour, 23 ℃, 50% RH for 1 hour After storage, the force required to completely separate the adhesive member when the adhesive member is pulled under the conditions of a peeling rate of 300 mm/min and a peeling angle of 180 degrees,
The C ₁ is after storing the adhesive member at 23° C. and 50% RH for 4 days, attaching the polarizing plate to a glass substrate, storing at 80° C. for 1 hour, and then at 23° C., 50% RH for 1 hour This is the force required to completely separate the adhesive member after storage, when the adhesive member is pulled under the conditions of a peeling rate of 300 mm/min and a peeling angle of 180 degrees.
14. The method of claim 13,
The adhesive member is
which is a polarizing plate,
no adhesive.
A display device comprising the adhesive member of claim 13 .