KR102497140B1 - Acrylic emulsion pressure snsitive adhesive composition - Google Patents

Abstract

The present invention relates to an acrylic emulsion pressure-sensitive adhesive composition, and more specifically, to an acrylic emulsion pressure-sensitive adhesive composition that is applied to an adherend and does not have a large change in viscosity and pH even after being exposed to the external environment, thereby stably realizing adhesive properties. It is about.

Description

Acrylic emulsion adhesive composition {ACRYLIC EMULSION PRESSURE SNSITIVE ADHESIVE COMPOSITION}

The present invention relates to an acrylic emulsion pressure-sensitive adhesive composition.

Pressure-Sensitive Adhesive (PSA) is a substance that adheres to an adherend with a small pressure. It is a viscoelastic material that is different from adhesives and has basic properties of initial adhesive strength, adhesive strength, and cohesive strength, and is used in various industries such as printing, chemicals, medicines, home appliances, automobiles, and stationery.

Pressure-sensitive adhesives can be classified into acrylic, rubber, silicone, EVA, etc. according to the monomers used in manufacturing, and can be classified into solvent, emulsion, and hot melt types according to the form.

In the past, most rubber-based adhesives or solvent-based adhesives were used for adhesive tapes and adhesive labels, but as the demand for eco-friendly adhesives increased, interest in non-solvent-type adhesives increased, and technology development was conducted. Currently, the use and production of non-solvent type adhesives have greatly increased, and are expected to continue to increase in the future.

Non-solvent type pressure-sensitive adhesives are typically prepared by aqueous emulsion polymerization, and in terms of economic feasibility and processability improvement, properties capable of stably realizing excellent adhesive properties with less generation of agglomerates are required.

In order to stably implement adhesive physical properties, there should be no significant change in the viscosity of the adhesive, but the viscosity changes under the influence of the environment in which the adhesive is exposed, such as temperature, humidity, and acidity.

Therefore, even when exposed to various environments, there is a continuing demand for an adhesive that can stably implement adhesive properties without a large change in viscosity.

The present specification is intended to provide an acrylic emulsion pressure-sensitive adhesive composition that can stably implement adhesive properties without significant change in viscosity and pH even after use.

According to one aspect of the present invention,

a1) a (meth)acrylic ester-based first monomer containing a chain-type alkyl group having 1 to 10 carbon atoms, a2) an unsaturated carboxylic acid-based second monomer, a3) an aromatic vinyl-based third monomer, and a4) a hydroxyl group a repeating unit derived from at least one monomer selected from the group consisting of a (meth)acrylic ester-based fourth monomer; and

b1) a repeating unit derived from a (meth)acrylic ester-based fifth monomer containing a multicyclic alkyl group having 6 to 15 carbon atoms;

An acrylic emulsion pressure-sensitive adhesive composition comprising an emulsion polymer is provided.

According to one embodiment of the invention, the first monomer is methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, Isobutyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth) Acrylates, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, isobornyl (meth)acrylate, and lauryl (meth) It may be one or more selected from the group consisting of acrylates.

According to another embodiment of the present invention, the second monomer may be at least one selected from the group consisting of maleic anhydride, fumaric acid, crotanoic acid, itaconic acid, and (meth)acrylic acid.

In this case, the second monomer-derived repeating unit is about 1 to about 10 parts by weight, preferably about 1 to about 5 parts by weight, or about 3 to about 3 parts by weight, based on 100 parts by weight of the repeating unit derived from the first monomer. It may be included in about 5 parts by weight.

According to another embodiment of the invention, the third monomer is styrene, methyl styrene, methyl styrene, butyl styrene, chloro styrene, vinyl benzoic acid, methyl vinyl benzoate, vinyl naphthalene, chloromethyl styrene, hydroxymethyl styrene and divinyl It may be one or more selected from the group consisting of benzene.

In this case, the third monomer-derived repeating unit is about 1 to about 10 parts by weight, preferably about 1 to about 5 parts by weight, or about 4 to about 4 parts by weight, based on 100 parts by weight of the repeating unit derived from the first monomer. It may be included in about 5 parts by weight.

According to another embodiment of the invention, the fourth monomer is 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4- Hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 2-hydroxyethylene glycol (meth)acrylate, ?? It may be at least one selected from the group consisting of 2-hydroxypropylene glycol (meth)acrylate.

And, at this time, the repeating unit derived from the fourth monomer is about 1 to about 10 parts by weight, preferably about 1 to about 5 parts by weight, or about 2 to about 2 parts by weight, based on 100 parts by weight of the repeating unit derived from the first monomer. It may be included in about 3 parts by weight.

According to another embodiment of the present invention, the multicyclic alkyl group of the fifth monomer may have a double ring or triple ring structure, and may have 7 to 15 carbon atoms constituting the ring. That is, the fifth monomer may be a (meth)acrylic ester-based monomer having a double ring or triple ring structure and including an alkyl group having 7 to 15 carbon atoms constituting the ring.

And, at this time, the repeating unit derived from the fifth monomer is about 1 to about 10% by weight, preferably about 1 to 5% by weight, or about 4 to about 5% by weight.

According to one embodiment of the present invention, the acrylic emulsion pressure-sensitive adhesive composition has a viscosity of about 1500 to about 2100 cPs at 25 ° C, and a viscosity change rate of about 20% or less, preferably about 0 to about 15%, or about 0.1 to about 0.1 It may be about 10%.

According to another embodiment of the present invention, the acrylic emulsion pressure-sensitive adhesive composition has a pH of about 8 to about 8.5 at 25 ° C, and a pH change value of about 1.5 or less, preferably about 0 to about 1.5, or about 0.1 to about may be 1.0.

And, according to another aspect of the invention,

a1) a (meth)acrylic ester-based first monomer containing a chain-type alkyl group having 1 to 10 carbon atoms, a2) an unsaturated carboxylic acid-based second monomer, a3) an aromatic vinyl-based third monomer, and a4) a hydroxyl group At least one monomer selected from the group consisting of a (meth)acrylic ester-based fourth monomer; and

b1) containing a (meth)acrylic ester-based fifth monomer containing a multicyclic alkyl group having 6 to 15 carbon atoms; monomer mixture; and

A composition for polymerization containing an emulsifier,

In the presence of an initiator, including the step of proceeding emulsion polymerization,

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

The emulsifier may include any one or more of a nonionic emulsifier and an anionic emulsifier.

At this time, the nonionic emulsifier; a dialkylene glycol alkyl ether-based compound containing an alkylene group having 2 to 5 carbon atoms and an alkyl group having 5 to 15 carbon atoms; Dialkylene glycol alkyl ester-based compounds containing an alkylene group having 2 to 5 carbon atoms and an alkyl group having 5 to 15 carbon atoms; and at least one selected from the group consisting of a dialkylene glycol alkyl amine compound including an alkylene group having 2 to 5 carbon atoms and an alkyl group having 5 to 15 carbon atoms.

And, the anionic emulsifier; It may include at least one selected from the group consisting of a sodium alkyldiphenyloxide disulfonate-based compound, a sodium polyoxyethylene alkyl ether sulfate-based compound, and a sodium dialkyl sulfosuccinate-based compound.

The emulsifier may be included in about 0.01 to about 1.0 parts by weight based on 100 parts by weight of the monomer mixture.

And, according to another aspect of the present invention,

write; and

Including an adhesive layer formed on at least one surface of the substrate,

The pressure-sensitive adhesive layer is provided with a pressure-sensitive adhesive sheet formed of the acrylic emulsion pressure-sensitive adhesive composition described above.

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

In addition, terms used in this specification are only used to describe exemplary embodiments, and are not intended to limit the present invention.

Singular expressions include plural expressions unless the context clearly dictates otherwise.

In this specification, terms such as "comprise", "comprise" or "having" are used to describe an implemented feature, number, step, component, or combination thereof, and one or more other features, numbers, or steps. , components, combinations or additions thereof are not excluded.

Also, in this specification, when each layer or element is referred to as being formed "on" or "above" each layer or element, it means that each layer or element is formed directly on each layer or element, or other This means that layers or elements may be additionally formed between each layer or on the object or substrate.

Since the present invention can have various changes and various forms, specific embodiments will be exemplified and described in detail below. However, it should be understood that this does not limit the present invention to the specific disclosed form, and includes all modifications, equivalents, and substitutes included in the spirit and technical scope of the present invention.

Hereinafter, the present invention will be described in detail.

According to one aspect of the present invention,

a1) a (meth)acrylic ester-based first monomer containing a chain-type alkyl group having 1 to 10 carbon atoms, a2) an unsaturated carboxylic acid-based second monomer, a3) an aromatic vinyl-based third monomer, and a4) a hydroxyl group a repeating unit derived from at least one monomer selected from the group consisting of a (meth)acrylic ester-based fourth monomer; and

b1) a repeating unit derived from a (meth)acrylic ester-based fifth monomer containing a multicyclic alkyl group having 6 to 15 carbon atoms;

An acrylic emulsion pressure-sensitive adhesive composition comprising an emulsion polymer is provided.

The inventors of the present invention, in an acrylic emulsion pressure-sensitive adhesive composition comprising an emulsion of latex particles prepared by emulsion polymerization of acrylate-based monomers, etc., in the case of preparing latex particles by using together a specific monomer having a multicyclic chemical structure , It was found that, while having excellent adhesive strength, the viscosity change was not large even after application to the adherend, so that excellent adhesive strength could be stably implemented, and the present invention was completed.

First, the acrylic emulsion pressure-sensitive adhesive composition according to one embodiment of the present invention includes emulsified polymer particles of a specific monomer, that is, latex particles, and each monomer may exist in the form of a repeating unit derived from the monomer in the latex particle there is.

monomer

First, in the emulsion polymerization for preparing the latex particles, a (meth)acrylic ester-based monomer containing a chain-like alkyl group having 1 to 10 carbon atoms may be used, which may be referred to as a first monomer. Accordingly, the latex particle may include a repeating unit derived from a (meth)acrylic ester-based monomer including a chain-like alkyl group having 1 to 10 carbon atoms, which may be referred to as a first repeating unit.

The first monomer is methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl ( 1 selected from the group consisting of meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, isobornyl (meth)acrylate, and lauryl (meth)acrylate It may be more than one species, and these may be used alone or in combination of two or more species.

And, in the emulsion polymerization for preparing the latex particles, an unsaturated carboxylic acid-based monomer may be further used, which may be referred to as a second monomer. Accordingly, the latex particles may include a repeating unit derived from an unsaturated carboxylic acid-based monomer, which may be referred to as a second repeating unit.

The second monomer may be at least one selected from the group consisting of maleic anhydride, fumaric acid, crotanoic acid, itaconic acid, and (meth)acrylic acid, and may be used alone or in combination of two or more.

And, in the emulsion polymerization, the second monomer is about 1 to about 10 parts by weight, preferably about 1 to about 5 parts by weight, or about 3 to about 5 parts by weight based on 100 parts by weight of the first monomer. Accordingly, in the emulsion polymer, the repeating unit derived from the second monomer is about 1 to about 10 parts by weight, preferably about 1 to about 10 parts by weight, based on 100 parts by weight of the repeating unit derived from the first monomer. About 5 parts by weight, or about 3 to about 5 parts by weight.

When the second monomer, that is, the unsaturated carboxylic acid-based monomer is used too much, a problem may occur as long as the viscosity rapidly increases in the polymerization reaction, and when used too little, the stability of the resulting latex particles deteriorates, and the particles Too many external cross-links may form, causing gelation.

And, in the emulsion polymerization for preparing the latex particles, an aromatic vinyl-based monomer may be further used, which may be referred to as a third monomer. Accordingly, the latex particle may include a repeating unit derived from an aromatic vinyl-based monomer, which may be referred to as a third repeating unit.

The third monomer is at least one selected from the group consisting of styrene, methylstyrene, methylstyrene, butylstyrene, chlorostyrene, vinylbenzoic acid, vinylmethylbenzoate, vinylnaphthalene, chloromethylstyrene, hydroxymethylstyrene, and divinylbenzene These may be used alone or in combination of two or more.

And, in the emulsion polymerization, the third monomer is about 1 to about 10 parts by weight, preferably about 1 to about 5 parts by weight, or about 4 to about 5 parts by weight based on 100 parts by weight of the first monomer. Accordingly, in the emulsion polymer, the repeating unit derived from the third monomer is about 1 to about 10 parts by weight, preferably about 1 to about 10 parts by weight, based on 100 parts by weight of the repeating unit derived from the first monomer. It may be included in about 5 parts by weight, or about 4 to about 5 parts by weight.

When the third monomer, that is, the aromatic vinyl-based monomer is used too much, adhesive strength may be reduced, and when used too little, cohesion between particles may be lowered, which may also cause a problem in that the adhesive strength is lowered.

And, in the emulsion polymerization for preparing the latex particles, a (meth)acrylic ester-based monomer containing a hydroxyl group may be further used, and this may be referred to as a fourth monomer. Accordingly, the latex particle may include a repeating unit derived from a (meth)acrylic ester-based monomer containing a hydroxyl group, which may be referred to as a fourth repeating unit.

The fourth monomer is 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-Hydroxyhexyl (meth)acrylate, 2-hydroxyethylene glycol (meth)acrylate, ?? It may be one or more selected from the group consisting of 2-hydroxypropylene glycol (meth)acrylate, and these may be used alone or in combination of two or more.

And, in the emulsion polymerization, the fourth monomer is about 1 to about 10 parts by weight, preferably about 1 to about 5 parts by weight, or about 2 to about 3 parts by weight based on 100 parts by weight of the first monomer. Accordingly, in the emulsion polymer, the repeating unit derived from the fourth monomer is about 1 to about 10 parts by weight, preferably about 1 to about 10 parts by weight, based on 100 parts by weight of the repeating unit derived from the first monomer. About 5 parts by weight, or about 2 to about 3 parts by weight.

When the fourth monomer, that is, the (meth)acrylic ester-based monomer containing a hydroxyl group is used in a large amount, the viscosity of the emulsion may be excessively increased, and when used too little, the adhesive strength may be deteriorated. can

And, in the acrylic emulsion pressure-sensitive adhesive composition according to one aspect of the present invention, in the emulsion polymerization for producing latex particles, a (meth)acrylic ester-based monomer containing a multicyclic alkyl group having 6 to 15 carbon atoms is further used do. This may be referred to as a fifth monomer. Accordingly, the latex particle may include a repeating unit derived from a (meth)acrylic ester-based monomer containing a multicyclic alkyl group having 6 to 15 carbon atoms, which may be referred to as a fifth repeating unit.

The fifth monomer includes a (meth)acrylate group at one end of the molecule and a multicyclic alkyl group having 6 to 15 carbon atoms at the opposite end.

In particular, the above-described latex particles may have a problem in that the viscosity gradually increases due to inter-particle interference between adjacent particles. When the fifth monomer is used in the latex particles of the acrylic emulsion pressure-sensitive adhesive composition, the above-described characteristics Due to the unique molecular structure, it is possible to reduce electrostatic interference between particles, thereby improving particle stability.

The fifth monomer may have an alkyl group having 6 to 15 carbon atoms and, in particular, a double ring or triple ring structure, and may have 7 to 15 carbon atoms constituting the ring.

The double ring or triple ring structure may be a bridged hydrocarbon ring or a sprio hydrocarbon ring; Among them, those having a bridged triple ring structure and having 7 to 15 carbon atoms constituting the ring may be preferable; having a bridged triple ring structure and having 8 to 12 carbon atoms constituting the ring; Alternatively, it may be more preferable to include the following norbornene structure in the molecule, that is, the structure of bicyclo [2.2.1] heptane.

As described above, the latex particles used in the acrylic emulsion pressure-sensitive adhesive composition according to one aspect of the present invention include a1) a (meth)acrylic ester-based first monomer containing a chain-like alkyl group having 1 to 10 carbon atoms, a2) an unsaturated carboxylic acid a repeating unit derived from at least one monomer selected from the group consisting of a second boxylic acid monomer, a3) a third aromatic vinyl monomer, and a4) a fourth (meth)acrylic ester monomer containing a hydroxyl group;

b1) It contains a repeating unit derived from a fifth (meth)acrylic ester-based monomer containing a multicyclic alkyl group having 6 to 15 carbon atoms, so that it can have excellent adhesion-related properties, and even after being applied to an adherend, There is no significant change in viscosity and pH value, so stable adhesion can be maintained for a long time.

At this time, the fifth monomer may be included in about 1 to about 10% by weight, preferably about 1 to 5% by weight, or about 4 to about 5% by weight based on 100% by weight of the total of the first to fifth monomers. Accordingly, in the emulsion polymer, the repeating unit derived from the fifth monomer is about 1 to about 10% by weight, preferably about 1 to about 10% by weight, based on 100% by weight of the total repeating units formed by the first to fifth monomers. may be included in about 1 to about 5% by weight, or about 4 to about 5% by weight.

When the fifth monomer, that is, a (meth)acrylic ester-based monomer containing a multicyclic alkyl group having 6 to 15 carbon atoms is used too much, radical reactivity is lowered during polymerization, resulting in unreacted latex particles or emulsion compositions. A problem of increasing the relative amount of the monomers may occur, and if too little is used, problems such as deterioration in particle stability and increase in viscosity due to electrostatic interference between particles may occur.

emulsion polymerization

As described above, the emulsion polymer particles included in the composition according to one embodiment of the present invention, that is, the latex particles, may be prepared by a generally known emulsion polymerization method.

Specifically, the method for producing the acrylic emulsion pressure-sensitive adhesive composition,

a1) a (meth)acrylic ester-based first monomer containing a chain-type alkyl group having 1 to 10 carbon atoms, a2) an unsaturated carboxylic acid-based second monomer, a3) an aromatic vinyl-based third monomer, and a4) a hydroxyl group At least one monomer selected from the group consisting of a (meth)acrylic ester-based fourth monomer; and

b1) containing a (meth)acrylic ester-based fifth monomer containing a multicyclic alkyl group having 6 to 15 carbon atoms; monomer mixture; and

A composition for polymerization containing an emulsifier;

A step of performing emulsion polymerization in the presence of an initiator may be included.

At this time, the polymerization temperature and polymerization time can be appropriately determined according to the case. For example, the polymerization temperature may be from about 50 °C to about 200 °C, and the polymerization time may be from about 0.5 hour to about 20 hours.

As the polymerization initiator usable in the emulsion polymerization, inorganic or organic peroxides may be used, and examples thereof include water-soluble initiators including potassium persulfate, sodium persulfate, and ammonium persulfate, cumene hydroperoxide, and benzoyl peroxide. Oil-soluble initiators including seeds and the like can be used.

In addition, an activator may be further included to promote the initiation of the peroxide reaction together with the polymerization initiator. Examples of the activator include sodium formaldehyde sulfoxylate, sodium ethylenediaminetetraacetate, ferrous sulfate, and dextrose. One or more selected from the group consisting of may be used.

The initiator may be included in an amount of about 0.1 to about 5 parts by weight, preferably 0.5 to 3 parts by weight, based on dry weight, based on 100 parts by weight of the monomer mixture.

According to one embodiment of the present invention, the acrylic emulsion pressure-sensitive adhesive composition may include other additives in addition to the above components without particular limitation within a range that does not deteriorate the desired effect of the present invention.

Specifically, an electrolyte may be further included to adjust the pH in the polymerization reaction and impart polymerization stability, for example, sodium hydroxide, sodium bicarbonate, sodium carbonate, sodium phosphate, sodium sulfate, sodium chloride, etc. It may include, but is not limited thereto. In addition, these may be used alone or in combination of two or more.

Emulsion polymerization may specifically proceed through the following steps.

A first step of dispersing an emulsifier in a solvent to prepare an emulsion;

A second step of preparing a pre-emulsion by mixing a monomer mixture including each monomer component and an emulsifier;

A third step of mixing the emulsion of the first step and the pre-emulsion of the second step in the presence of an initiator and performing emulsion polymerization.

In a specific embodiment of the present invention, the above-described acrylic emulsion pressure-sensitive adhesive composition may be specifically prepared by the following method, but is not necessarily limited thereto.

First, as a first step, an emulsion containing an emulsifier is prepared. This is separate from the pre-emulsion manufacturing process described below. As the emulsifier, an anionic emulsifier may be used alone or an anionic emulsifier and the aforementioned nonionic emulsifier may be used together, and an emulsion may be prepared by mixing the emulsifier component and a solvent such as water.

In the process of preparing the emulsion, initial micelle particles having a size of several nanometers may be stably formed.

And, as a second step, in the process of preparing a pre-emulsion containing the above-described monomer mixture, the above-described monomers, emulsifier, etc. are mixed with water to prepare a pre-emulsion.

At this time, as the emulsifier, an anionic emulsifier may be used alone or an anionic emulsifier and the aforementioned nonionic emulsifier may be used together. In this process, nano-sized latex particles may be formed in the pre-emulsion.

That is, the above-described emulsifier may be used in any one or more of the emulsion preparation step and the pre-emulsion preparation step.

Then, in the third step, after adding the polymerization initiator to the emulsion prepared above, the pre-emulsion and the polymerization initiator are continuously added at an equal ratio for a predetermined time.

In a non-limiting embodiment of the present invention, the content of the polymerization initiator added to the emulsion may be about 0.001 to about 0.02 parts by weight based on 100 parts by weight of the monomer mixture, and the content of the polymerization initiator added together with the pre-emulsion, It may be about 0.1 to about 0.5 parts by weight based on 100 parts by weight of the monomer mixture, and the time of continuous addition may be about 3 hours to about 7 hours.

Through this process, suspended monomers or polymers in the pre-emulsion can be introduced into the initial particles produced in the emulsion.

The products of this reaction may then undergo a heating polymerization process in the presence of an additional polymerization initiator, through which polymerization of the remaining monomers is achieved.

At this time, the polymerization initiator may be added in an amount of about 0.001 to about 0.02 parts by weight based on 100 parts by weight of the monomer mixture, and the heating polymerization may be performed at a temperature of about 75 to about 85 ° C. for about 40 minutes to about 80 minutes. .

The manufacturing method of such an acrylic emulsion pressure-sensitive adhesive composition is dualized into an emulsion preparation process and a pre-emulsion preparation process, and then can be proceeded by a simple method of mixing the pre-emulsion with the emulsion, so that the conventional high-solids, low-viscosity acrylic emulsion pressure-sensitive adhesive Process stability and productivity can be improved compared to methods for preparing the composition.

Meanwhile, in the process of preparing the pre-emulsion, a chain transfer agent may be used. The chain transfer agent serves to introduce homopolymers, which are polymers composed of only one kind of monomer, into micelles, and may include sodium carbonate, sodium methylallyl sulfonate, n-dodecyl mercaptan, etc., but the present invention It is not necessarily limited to this.

And, in one embodiment of the present invention, after the polymerization step, a step of adjusting the pH may be further performed, and at this time, the pH may be adjusted to about 8 to about 8.5.

For adjusting the pH of the acrylic emulsion resin, a method commonly used in the art may be used without particular limitation. or an organic amine or the like may be used.

emulsifier

And, the emulsifier may further include any one or more of a nonionic emulsifier and an anionic emulsifier.

Such an emulsifier is a substance that has both a hydrophilic group and a hydrophobic group, and forms a micelle structure during emulsion polymerization, allowing polymerization of each monomer to occur inside the micelle structure.

Emulsifiers commonly used in emulsion polymerization may be divided into anionic emulsifiers, cationic emulsifiers, and nonionic emulsifiers, etc., and two or more types may be mixed and used in terms of polymerization stability in emulsion polymerization.

Specifically, in the case of the anionic emulsifier, at least one selected from the group consisting of a sodium alkyldiphenyloxide disulfonate-based compound, a sodium polyoxyethylene alkyl ether sulfate-based compound, and a sodium dialkyl sulfosuccinate-based compound. can include

The nonionic emulsifier may include a dialkylene glycol alkyl ether compound including an alkylene group having 2 to 5 carbon atoms and an alkyl group having 5 to 15 carbon atoms; Dialkylene glycol alkyl ester-based compounds containing an alkylene group having 2 to 5 carbon atoms and an alkyl group having 5 to 15 carbon atoms; And at least one selected from the group consisting of an alkylene group having 2 to 5 carbon atoms and a dialkylene glycol alkyl amine compound containing an alkyl group having 5 to 15 carbon atoms, which can be used alone or in combination of two or more. However, the present invention is not necessarily limited to the type of emulsifier.

The emulsifier may be used in an amount of about 0.01 to about 1 part by weight or about 0.01 to about 0.5 part by weight, based on 100 parts by weight of the total monomer components used in the manufacture of the latex particles.

menstruum

According to one embodiment of the invention, the acrylic emulsion pressure-sensitive adhesive composition may further include an aqueous solvent such as water in addition to the above-described emulsion polymer particles, that is, latex particles.

In this case, the aqueous solvent may be used in an amount of about 10 to about 1,000 parts by weight based on 100 parts by weight of the latex particles, in terms of stability and viscosity control of the latex particles, for example, based on the total amount of the composition, the total It can be used to adjust the total solid content (TSC) from about 10 to about 60% by weight.

Properties

Due to the characteristic composition described above, the acrylic emulsion pressure-sensitive adhesive composition according to an embodiment of the present invention has a viscosity of about 1500 to about 2100 cPs at about 25 ° C, and a viscosity change rate, more specifically, when exposed to 25 ° C for 15 days or more Even so, the viscosity change rate may be about 20% or less, preferably about 0 to about 15%, or about 0.1 to about 10%.

In addition, such an acrylic emulsion pressure-sensitive adhesive composition may have a viscosity change rate of about 20% or less, preferably about 0 to about 15%, or about 0.1 to about 13%, even when exposed to 50 ° C. for 15 days or more.

According to another embodiment of the present invention, the acrylic emulsion pressure-sensitive adhesive composition has a pH of about 8 to about 8.5 at 25 ° C, and a pH change value, more specifically, even when exposed to 25 ° C for 15 days or more, the pH change value up to about 1.5, preferably from about 0 to about 1.5, or from about 0.1 to about 1.0.

In addition, such an acrylic emulsion pressure-sensitive adhesive composition may have a pH change value of about 1.5 or less, preferably about 0 to 1.5, or about 0.1 to 1.2, even when exposed to 50 ° C. for 15 days or more.

Sheet

The acrylic emulsion pressure-sensitive adhesive composition of the present invention prepared according to the above method may be applied to a pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive sheet may be an adhesive film or sheet for building interior and exterior materials, interior materials, advertising films, or labels, but the present invention It is not necessarily limited only to these.

Such a sheet may include a substrate; and an adhesive layer formed on one side or both sides of the substrate, and the adhesive layer may be formed of the acrylic emulsion adhesive composition described above.

According to one embodiment of the invention, the pressure-sensitive adhesive sheet has FINAT TEST METHOD NO. Initial adhesion (Loop tack) according to 9 may be about 12 N / in or more, or about 13 to about 15 N / in.

In addition, the pressure-sensitive adhesive sheet has FINAT TEST METHOD NO. The 90 degree peel force according to 2 may be about 8 N/in or more, preferably about 9 to about 10 N/in.

As described above, the acrylic emulsion pressure-sensitive adhesive composition according to one embodiment of the present invention, even after being applied to an adherend and exposed to an external environment, does not have a large change in viscosity and pH, so that adhesive properties can be stably implemented.

Hereinafter, the action and effect of the invention will be described in more detail through specific examples of the invention. However, these embodiments are only presented as examples of the invention, and the scope of the invention is not determined thereby.

<Example>

Preparation of acrylic emulsion pressure-sensitive adhesive composition

Example 1

209 g of water and 1.62 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate were added to a 3 L glass reactor equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet pipe and reflux condenser, and the inside of the reactor was purged with nitrogen while stirring. Then, the temperature was raised to 80 °C under a nitrogen atmosphere and maintained for 60 minutes.

Separately, 561 g of 2-ethylhexylacrylate, 56 g of methyl methacrylate (above, first monomer), 20 g of acrylic acid (second monomer), 28 g of styrene (third monomer), hydroxyl for preparing a pre-emulsion Ethyl acrylate 14 g (fourth monomer) 8-tricyclo[5.2.1.0 ^2,6 ]decanyl methacrylate 35 g (fifth monomer), normal dodecyl mercaptan 0.1 g and diethylene glycol dodecyl ether 0.7 g, a solution consisting of 9 g of 30 wt% sodium polyoxyethylene lauryl ether sulfate, 7 g of 50 wt% sodium alkyldiphenyloxide disulfonate, 1.4 g of sodium hydroxide, and 100 g of water was added The mixture was added and mixed with a stirrer to prepare a whitish emulsion.

7 g of a 5 wt% ammonium persulfate solution was added to the glass reactor and stirred for 5 minutes to dissolve. The emulsion and 100 g of a 5% by weight aqueous solution of ammonium persulfate were uniformly and continuously introduced into the glass reactor for 5.5 hours, the temperature was raised to 80° C., maintained at this temperature for 1 hour, and then cooled to room temperature to prepare an acrylic emulsion. did

A 5% by weight aqueous solution of sodium hydroxide was added to the acrylic emulsion to adjust the pH to 6-7.

Then, as a nonionic emulsifier, 4.5 g of polyethylene glycol was added to terminate the reaction, and an acrylic emulsion pressure-sensitive adhesive composition was obtained.

Example 2

An acrylic emulsion pressure-sensitive adhesive composition was obtained in the same manner as in Example 1, except that diethylene glycol dodecyl ether, a nonionic emulsifier, was not added during the pre-emulsion preparation and was added after the polymerization reaction. .

Comparative Example 1

Except for using the same amount of methyl methacrylate instead of 35 g of the fifth monomer, 8-tricyclo[5.2.1.0 ^2,6 ]decanyl methacrylate, the same procedure as in Example 1 was performed, acrylic An emulsion pressure sensitive adhesive composition was obtained.

Viscosity and pH measurement

With respect to the acrylic emulsion pressure-sensitive adhesive composition obtained in the above Examples and Comparative Examples, the pH was measured using a Mettler Toledo pH meter.

In addition, with respect to the acrylic emulsion pressure-sensitive adhesive composition obtained in the above Examples and Comparative Examples, the viscosity was measured at 25 ° C. using a Brookfield Viscometer DIV + III Rheometer.

Thereafter, the acrylic emulsion pressure-sensitive adhesive composition obtained in the above Examples and Comparative Examples was exposed to 25 ° C. temperature conditions for 15 days, and the pH and viscosity were measured again. Apart from this, the acrylic emulsion pressure-sensitive adhesive composition obtained in Examples and Comparative Examples was exposed to 50 ° C temperature conditions for 15 days, and pH and viscosity were measured again.

Manufacture of adhesive sheets

The acrylic emulsion pressure-sensitive adhesive composition was applied on a silicone-coated release paper and dried in an oven at 120° C. for 1 minute to have a dry thickness of 20 μm. This was laminated with paper to make a paper label and cut to a size of 1 inch ² to prepare a paper label specimen.

Adhesion property measurement

Initial adhesion (loop tack) measurement

For the paper label specimen prepared above, it was measured according to FTM 9 of the FINAT test method.

The specimen was prepared in a ring shape, and was brought into contact with a stainless steel (SUS 304) surface for 5 seconds without applying pressure.

It was measured while peeling at a speed of 300 mm/min using a TA Texture Analyzer device for 5 seconds.

90 degree peel strength measurement

For the paper label specimen prepared above, it was measured according to FTM 2 of the FINAT test method.

The specimen was prepared, attached to a stainless steel surface, and then compressed by reciprocating twice at a speed of 300 mm/min with a 2 kg roller. After aging at room temperature for 20 minutes, measurement was performed while peeling at a rate of 300 mm/min using a TA Texture Analyzer for 5 seconds.

How to measure shear

The paper label specimen prepared above was measured according to FTM 8 of the FINAT test method.

Prepare a specimen, attach it so that the stainless steel surface and the attachment surface are 1 inch x 0.5 inch, and then reciprocate twice with a 2 kg roller to compress. After 10 minutes, the attached sheet was attached to a wall inclined by about 2 degrees, and a weight of 1,000 g was hung at the bottom, and the time for the sheet to separate from the attached surface was measured in a measurement environment of 23 ° C. and 50% humidity.

The measurement results are summarized in Tables 1 and 2 below.

viscosity
(Lv, 60 rpm; cPs) pH Early
(25 ℃) after 15 days
(25 ℃) after 15 days
(50 ℃) Early
(25 ℃) after 15 days
(25 ℃) after 15 days
(50 ℃) Example 1 1870 1900 2100 8.3 7.7 7.2 Example 2 2020 1910 2002 8.2 7.8 7.1 Comparative Example 1 2300 1540 1020 8.2 6.6 5.7

initial adhesion
(N/in) 90 degree peel strength
(N/in) retention
(min) Example 1 14.5 9.8 155 Example 2 13.7 9.0 170 Comparative Example 1 13.3 10.3 180

Referring to Tables 1 and 2, it can be seen that the acrylic emulsion pressure-sensitive adhesive composition according to the embodiment of the present invention can implement excellent adhesion-related physical properties, and the change in viscosity and pH is not large even when exposed to the external environment.

Specifically, when a paper label is manufactured with the acrylic emulsion adhesive composition according to Examples 1 and 2, the initial adhesive strength according to Finat Test Method No. 9 is about 13.5 N / in or more, and 90 according to Finat Test Method No. 2 The peel strength value was about 9 or more, and the adhesive retention according to Finat Test Method No. 8 was also about 150 minutes or more, indicating that all physical properties related to point/adhesion were excellent.

In addition, the acrylic emulsion pressure-sensitive adhesive composition according to Examples 1 and 2, even when exposed to about 15 days at about 50 ° C., it can be seen that the increase in viscosity is controlled within about 12% or the viscosity is rather slightly reduced, and the pH is also It can be clearly seen that the change value is only about 1.

In the case of the comparative example, adhesion-related physical properties were implemented to some extent excellent, but it was found that the viscosity and pH change occurred severely when exposed to the external environment.

Specifically, in the case of Comparative Example 1, when exposed to about 50 ° C. for about 15 days, the viscosity was lowered by about 50%, and it was clearly confirmed that the pH value also reached about 2.5.

Claims (18)

a1) a (meth)acrylic ester-based first monomer containing a chain-type alkyl group having 1 to 10 carbon atoms, a2) an unsaturated carboxylic acid-based second monomer, a3) an aromatic vinyl-based third monomer, and a4) a hydroxyl group a repeating unit derived from at least one monomer selected from the group consisting of a (meth)acrylic ester-based fourth monomer; and
b1) a repeating unit derived from a (meth)acrylic ester-based fifth monomer containing a multicyclic alkyl group having 6 to 15 carbon atoms;
An acrylic emulsion pressure-sensitive adhesive composition comprising an emulsion polymer.
According to claim 1,
The first monomer is methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl ( 1 selected from the group consisting of meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, isobornyl (meth)acrylate, and lauryl (meth)acrylate More than one species, acrylic emulsion pressure-sensitive adhesive composition.
According to claim 1,
The second monomer is at least one selected from the group consisting of maleic anhydride, fumaric acid, crotanoic acid, itaconic acid, and (meth)acrylic acid, acrylic emulsion pressure-sensitive adhesive composition.
According to claim 1,
The second monomer-derived repeating unit is contained in 1 to 10 parts by weight based on 100 parts by weight of the first monomer-derived repeating unit, acrylic emulsion pressure-sensitive adhesive composition.
According to claim 1,
The third monomer is at least one selected from the group consisting of styrene, methylstyrene, methylstyrene, butylstyrene, chlorostyrene, vinylbenzoic acid, vinylmethylbenzoate, vinylnaphthalene, chloromethylstyrene, hydroxymethylstyrene, and divinylbenzene. , Acrylic emulsion adhesive composition.
According to claim 1,
The third monomer-derived repeating unit is contained in 1 to 10 parts by weight based on 100 parts by weight of the first monomer-derived repeating unit, acrylic emulsion pressure-sensitive adhesive composition.
According to claim 1,
The fourth monomer is 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-Hydroxyhexyl (meth)acrylate, 2-hydroxyethylene glycol (meth)acrylate, ?? At least one selected from the group consisting of 2-hydroxypropylene glycol (meth) acrylate, acrylic emulsion pressure-sensitive adhesive composition.
According to claim 1,
The fourth monomer-derived repeating unit is contained in 1 to 10 parts by weight based on 100 parts by weight of the first monomer-derived repeating unit, acrylic emulsion pressure-sensitive adhesive composition.
According to claim 1,
The multi-cyclic alkyl group of the fifth monomer has a double ring or triple ring structure, and the number of carbon atoms constituting the ring is 7 to 15, acrylic emulsion pressure-sensitive adhesive composition.
According to claim 1,
The fifth monomer-derived repeating unit is contained in 1 to 10% by weight relative to the total of 100% by weight of the first to fifth monomer-derived repeating units, acrylic emulsion pressure-sensitive adhesive composition.
According to claim 1,
A viscosity of 1500 to 2100 cPs at 25 ° C., and a viscosity change rate of 20% or less, an acrylic emulsion pressure-sensitive adhesive composition.
According to claim 1,
At 25 ° C., the pH is 8 to 8.5, and the pH change value is 1.5 or less, an acrylic emulsion pressure-sensitive adhesive composition.
a1) a (meth)acrylic ester-based first monomer containing a chain-type alkyl group having 1 to 10 carbon atoms, a2) an unsaturated carboxylic acid-based second monomer, a3) an aromatic vinyl-based third monomer, and a4) a hydroxyl group At least one monomer selected from the group consisting of a (meth)acrylic ester-based fourth monomer; and
b1) containing a (meth)acrylic ester-based fifth monomer containing a multicyclic alkyl group having 6 to 15 carbon atoms; monomer mixture; and
A composition for polymerization containing an emulsifier;
In the presence of an initiator, including the step of proceeding emulsion polymerization,
Method for producing an acrylic emulsion pressure-sensitive adhesive composition.
According to claim 13,
The emulsifier, a method for producing an acrylic emulsion pressure-sensitive adhesive composition comprising at least one emulsifier of a nonionic emulsifier and an anionic emulsifier.
According to claim 14,
The nonionic emulsifier; a dialkylene glycol alkyl ether-based compound containing an alkylene group having 2 to 5 carbon atoms and an alkyl group having 5 to 15 carbon atoms; Dialkylene glycol alkyl ester-based compounds containing an alkylene group having 2 to 5 carbon atoms and an alkyl group having 5 to 15 carbon atoms; and at least one selected from the group consisting of an alkylene group having 2 to 5 carbon atoms and a dialkylene glycol alkyl amine compound including an alkyl group having 5 to 15 carbon atoms;
Method for producing an acrylic emulsion pressure-sensitive adhesive composition.
According to claim 14,
The anionic emulsifier; containing at least one selected from the group consisting of a sodium alkyldiphenyloxide disulfonate-based compound, a sodium polyoxyethylene alkyl ether sulfate-based compound, and a sodium dialkyl sulfosuccinate-based compound;
Method for producing an acrylic emulsion pressure-sensitive adhesive composition.
According to claim 14,
The emulsifier is contained in 0.01 to 1.0 parts by weight based on 100 parts by weight of the monomer mixture, a method for producing an acrylic emulsion pressure-sensitive adhesive composition.
write; and
Including an adhesive layer formed on at least one surface of the substrate,
The pressure-sensitive adhesive layer is formed of the acrylic emulsion pressure-sensitive adhesive composition according to claim 1, the pressure-sensitive adhesive sheet.