KR102524479B1 - Acrylic emulsion pressure snsitive adhesive composition - Google Patents

Abstract

The present invention relates to an acrylic emulsion pressure-sensitive adhesive composition, and more specifically, an acrylic emulsion pressure-sensitive adhesive composition that can realize excellent adhesive properties, does not have a separate color, does not cause yellowing, and is advantageous for bonding transparent materials, etc. 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 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.

Particularly, in recent years, such solvent-free pressure-sensitive adhesives are widely used for bonding transparent films, etc., and the physical properties of the pressure-sensitive adhesive are changed due to the influence of the environment, which may deteriorate the optical properties of the film.

Therefore, even when exposed to various environments, the change in physical properties is not large, and there is a continuing demand for an adhesive capable of stably implementing adhesive properties.

An object of the present specification is to provide an acrylic emulsion pressure-sensitive adhesive composition capable of stably implementing adhesive properties without significant change in physical properties even when exposed to various environments.

According to one aspect of the present invention,

For all monomer-derived repeating units constituting the emulsion polymer,

A) 90 to 98 mol% of a repeating unit derived from a (meth)acrylic ester first monomer containing a chain alkyl group having 1 to 10 carbon atoms; and

B) an acrylic emulsion pressure-sensitive adhesive composition comprising an emulsion polymer composed of 2 to 10 mol% of repeating units derived from at least one monomer selected from the group consisting of b1) unsaturated carboxylic acid-based second monomer and b2) aromatic vinyl-based third monomer Provided.

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 There may be more than one species.

In addition, 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, the third monomer is 1 selected from the group consisting of styrene, methylstyrene, methylstyrene, butylstyrene, chlorostyrene, vinylbenzoic acid, vinylmethyl benzoate, vinylnaphthalene, chloromethylstyrene, hydroxymethylstyrene and divinylbenzene There may be more than one species.

According to one embodiment of the invention, the acrylic emulsion pressure-sensitive adhesive composition, with respect to the entire monomer-derived repeating unit constituting the emulsion polymer;

A) about 94 to about 97 mol% of a repeating unit derived from a (meth)acrylic ester-based first monomer containing a chain-like alkyl group having 1 to 10 carbon atoms;

B) It is more preferable to include an emulsion polymer composed of about 3 to about 6 mol% of repeating units derived from at least one monomer selected from the group consisting of b1) unsaturated carboxylic acid-based second monomer and b2) aromatic vinyl-based third monomer can do.

Meanwhile, according to another aspect of the invention,

Based on the total monomer components, A) 90 to 98 mol% of a (meth)acrylic ester-based first monomer containing a chain alkyl group having 1 to 10 carbon atoms; B) 2 to 10 mol% of a monomer mixture of at least one monomer selected from the group consisting of b1) an unsaturated carboxylic acid-based second monomer and b2) an aromatic vinyl-based third monomer; polymerization initiators; And a method for producing an acrylic emulsion pressure-sensitive adhesive composition comprising the step of emulsion polymerization of a composition for polymerization containing an emulsifier is provided.

The emulsifier may include at least one selected from the group consisting of anionic emulsifiers, cationic emulsifiers, and nonionic emulsifiers.

At this time, the anionic emulsifier is sodium alkyl diphenyl ether disulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene aryl ether sulfate, sodium alkyl sulfate, sodium alkyl benzene sulfonate, and dialkyl sodium sulfosaccharide It may include one or more selected from the group consisting of cinate.

In addition, the nonionic emulsifier may include at least one selected from the group consisting of polyethylene oxide alkyl aryl ethers, polyethylene oxide alkyl amines, and polyethylene oxide alkyl esters.

The emulsifier may be preferably used in an amount of about 0.01 to about 10 parts by weight, or about 0.1 to about 5 parts by weight, based on 100 parts by weight of the monomer components.

And, the composition for polymerization may further include an aqueous solvent.

On the other hand, according to another aspect of the invention, a transparent substrate; An adhesive member including a pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition described above is provided on at least one surface of the transparent substrate.

In the adhesive member, the adhesive layer formed of the acrylic emulsion pressure-sensitive adhesive composition has a b value of about 0.1 or less, or about 0 to about 0.1, preferably about 0.03 to about, measured according to the CIE 1976 L*a*b* standard. 0.1, or from about 0.03 to about 0.09.

And, in the adhesive member, the adhesive layer formed of the acrylic emulsion pressure-sensitive adhesive composition has a b value of about 0.25 or less measured according to the CIE 1976 L*a*b* standard after exposure at about 70 ° C. for about 3 hours. , or from about 0 to 0.25, preferably from about 0.04 to 0.25, or from about 0.04 to about 0.23.

And, the adhesive member, FINAT TEST METHOD NO. The 90 degree peel strength measured according to the 2 criteria may be about 5 N/in or more, preferably about 7.5 to about 10 N/in.

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 addition, 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, This means that another layer or element may be additionally formed on the object or substrate between each layer.

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,

For all monomer-derived repeating units constituting the emulsion polymer,

A) 90 to 98 mol% of a repeating unit derived from a (meth)acrylic ester first monomer containing a chain alkyl group having 1 to 10 carbon atoms;

B) an acrylic emulsion pressure-sensitive adhesive composition comprising an emulsion polymer composed of 2 to 10 mol% of repeating units derived from at least one monomer selected from the group consisting of b1) unsaturated carboxylic acid-based second monomer and b2) aromatic vinyl-based third monomer Provided.

In the present specification, the fact that the emulsion polymer is composed of repeating units derived from the monomers means that the repeating units derived from the monomers included in the emulsion polymer are all repeating units derived from the first, second, and third monomers. constituted, and does not include any repeating units derived from other monomers, and in particular, when adding at least one of the first monomer-derived repeating unit and the second and third monomer-derived repeating units, the total number of 100 This means that the mole percent

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., when preparing latex particles only with a combination of specific monomers, while having excellent adhesive strength, In particular, it was discovered that even when exposed to the external environment, there is no change in adhesive retention or color, so that physical properties can be implemented very stably, 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 is present in the form of a repeating unit derived from the monomer in the latex particle. can

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 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.

And, the aromatic vinyl monomer is selected from the group consisting of styrene, methylstyrene, methylstyrene, butylstyrene, chlorostyrene, vinylbenzoic acid, vinylmethylbenzoate, vinylnaphthalene, chloromethylstyrene, hydroxymethylstyrene and divinylbenzene 1 or more types are mentioned.

As described above, the latex particles used in the acrylic emulsion pressure-sensitive adhesive composition according to one aspect of the present invention include A) a (meth)acrylic ester-based first monomer containing a chain-like alkyl group having 1 to 10 carbon atoms and B) b1) Contains only repeating units derived from one or more monomers selected from the group consisting of an unsaturated carboxylic acid-based second monomer and b2) an aromatic vinyl-based third monomer, and can exhibit excellent adhesive strength, even when exposed to an external environment, adhesive properties and Optical properties such as color do not change.

In the case of emulsion adhesives using conventionally used vinyl acetate or monomers containing other functional groups, there is a problem of deterioration of adhesive properties or color change due to yellowing under conditions exposed to the external environment after drying or adhesion. can happen

However, the acrylic emulsion pressure-sensitive adhesive composition according to one aspect of the present invention uses only the above-described first monomer and second and/or third monomers, and in particular, contains only a specific amount of these monomers to achieve excellent initial adhesive strength. In addition, even when exposed to the external environment, there is an advantage that yellowing hardly occurs.

From this point of view, the acrylic emulsion pressure-sensitive adhesive composition, A) about 94 to about 97 mol% of a repeating unit derived from a (meth)acrylic ester-based first monomer containing a chain-like alkyl group having 1 to 10 carbon atoms; and B) an emulsion polymer composed of about 3 to about 6 mol% of repeating units derived from at least one monomer selected from the group consisting of b1) an unsaturated carboxylic acid-based second monomer and b2) an aromatic vinyl-based third monomer. may be desirable.

If the content is out of the above range or other monomers are used, problems such as deterioration in point and adhesive strength of the prepared acrylic emulsion pressure-sensitive adhesive composition or decrease in point and adhesive retention may occur. In particular, the acrylic emulsion pressure-sensitive adhesive composition After the adhesive layer formed by is exposed to the external environment, a yellowing phenomenon may occur.

Acrylic emulsion pressure-sensitive adhesive composition according to an embodiment of the present invention, due to the above compositional characteristics, the b value measured according to the CIE 1976 L*a*b* standard is about 0.1 or less, or about 0 to about 0.1, preferably is from about 0.03 to about 0.1, or from about 0.03 to about 0.09, and may have little color.

In addition, the acrylic emulsion pressure-sensitive adhesive composition is exposed to about 70 ℃ for about 3 hours, even after drying is completed, the b value measured according to the CIE 1976 L * a * b * standard is about 0.25 or less, or about 0 to about 0 0.25, preferably from about 0.04 to 0.25, or from about 0.04 to about 0.23, and the effect of yellowing may be very small.

emulsion polymerization

Emulsion polymer particles included in the composition according to one embodiment of the present invention, that is, latex particles;

For all monomer components,

A) 90 to 98 mol% of a (meth)acrylic ester-based first monomer containing a chain alkyl group having 1 to 10 carbon atoms;

B) 2 to 10 mol% of a monomer mixture of at least one monomer selected from the group consisting of b1) an unsaturated carboxylic acid-based second monomer and b2) an aromatic vinyl-based third monomer;

polymerization initiators; and

Including the step of emulsion polymerization of a composition for polymerization containing an emulsifier,

It can be prepared by emulsion polymerization.

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 during the emulsion polymerization, inorganic or organic peroxides may be used, for example, water-soluble polymerization initiators including potassium persulfate, sodium persulfate, and ammonium persulfate, cumene hydroperoxide, Oil-soluble polymerization initiators including benzoyl peroxide 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 polymerization initiator may be included in about 0.1 to about 10 parts by weight, preferably about 0.1 to about 5 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 a polymerization 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, a cationic emulsifier, and the above-described nonionic emulsifier may be used together, and an emulsion may be prepared by mixing these emulsifier components 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 to about 1 part 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 is, It may be about 0.1 to about 2 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 further added in an amount of about 0.1 to about 10 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, the step of adjusting the pH may be further performed after the polymerization step.

Adjustment of the pH of the acrylic emulsion resin may be performed using a method commonly used in the art without particular limitation. or an organic amine or the like may be used.

emulsifier

In addition, the emulsifier used in the emulsion polymerization may include at least one selected from the group consisting of an anionic emulsifier, a cationic emulsifier, and a nonionic 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. In terms of polymerization stability in emulsion polymerization, two or more types may be mixed and used.

Specifically, the nonionic emulsifier may include at least one selected from the group consisting of polyethylene oxide alkyl aryl ethers, polyethylene oxide alkyl amines, and polyethylene oxide alkyl esters.

And, the anionic emulsifier is sodium alkyl diphenyl ether disulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene aryl ether sulfate, sodium alkyl sulfate, sodium alkyl benzene sulfonate, and dialkyl sodium sulfosuccinic It may include one or more selected from the group consisting of nates.

These may be used alone or in combination of two or more, and may be more effective when an anionic emulsifier and a nonionic emulsifier are mixed and used, but the present invention is not necessarily limited to these types of emulsifiers.

The emulsifier may be used in an amount of about 0.1 to about 10 parts by weight or about 1 to about 5 parts by weight, based on 100 parts by weight of the total monomer components used in the manufacture of the latex particles.

If the amount of the emulsifier used is too large, the particle size of the latex particles becomes small, which may cause problems such as a decrease in viscosity and adhesive strength. Stability of the resulting latex particles may also be deteriorated.

menstruum

According to one embodiment of the invention, the composition for polymerization may further include an aqueous solvent such as water in addition to the above-described emulsifier or monomer component.

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.

When the solvent is used too little, the viscosity of the acrylic emulsion pressure-sensitive adhesive composition increases, and during emulsion polymerization, the stability of latex particles may decrease. This degradation problem may occur.

adhesive member

The acrylic emulsion pressure-sensitive adhesive composition of the present invention prepared according to the above method may be applied to an adhesive member such as 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. , the present invention is not necessarily limited only to these.

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

According to one embodiment of the invention, the adhesive member, FINAT TEST METHOD NO. The 90 degree peel strength measured according to the criterion of 2 may be about 5 N/in or more, preferably about 7.5 N/in or more, and the upper limit is not significant, but about 15 N/in or less, or about 10 It may be N/in or less.

As described above, the acrylic emulsion pressure-sensitive adhesive composition according to one embodiment of the present invention, while being able to realize excellent adhesive strength, does not change in color even after being exposed to the external environment, especially when used for bonding transparent materials, etc. It does not impair its own optical properties.

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.

Preparation of acrylic emulsion pressure-sensitive adhesive composition

Example 1

220 g of water and 10 g of 26% by weight sodium polyoxyethylene arylether sulfate were added to a 3 L glass reactor equipped with a thermometer, stirrer, dropping funnel, nitrogen gas inlet pipe and reflux condenser, followed by stirring. After purging the inside of the reactor with nitrogen, the temperature was raised to 80° C. under a nitrogen atmosphere and maintained for 60 minutes.

Separately, 494 g of 2-ethyl hexyl acrylate, 90 g of methyl methacrylate, 12 g of styrene, and 6 g of acrylic acid were added to a 2 L beaker, followed by stirring for 30 minutes to prepare a monomer mixture.

Here, a solution consisting of 20 g of sodium polyoxyethylene lauryl ether sulfate at a concentration of 26% by weight, 10 g of a solution of sodium alkyldiphenyloxide disulfonate at a concentration of 45% by weight, 2 g of sodium carbonate, and 180 g of water was added. and stirred to prepare a white turbid pre-emulsion.

3 g of ammonium persulfate having a concentration of 20% by weight was added to a glass reactor containing the emulsion and dissolved by stirring for 10 minutes.

The pre-emulsion and 25 g of ammonium persulfate at a concentration of 7% by weight were uniformly and continuously introduced into the glass reactor for 5 hours, and then polymerization was performed at 80° C. for 1 hour.

It was cooled to room temperature, and the pH was adjusted to 5-7 by adding a 10% by weight aqueous solution of sodium hydroxide to prepare an acrylic emulsion pressure-sensitive adhesive composition.

Examples 2 to 6

Acrylic emulsion adhesive by the same method as in Example 1, except that the type of monomer and the content of each monomer component were changed, and the content of 7% by weight ammonium persulfate introduced together with the pre-emulsion was changed. A composition was prepared.

The contents are summarized in Table 1 below.

unit
(g) Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 2-EHA 494 374 314 404 349 0 BA 0 120 180 120 180 577 MMA 90 90 90 60 60 12 SM 12 12 12 12 0 0 AA 6 6 6 6 15 15 7% APS 25 25 25 25 102 25

* 2-EHA: 2-ethyl hexylacrylate; BA: butyl acrylate; MMA: methyl methacrylate; SM: styrene; AA: acrylic acid; 7% APS: ammonium persulfate at a concentration of 7% by weight

Comparative Example 1

220 g of water and 10 g of 26% by weight sodium polyoxyethylene arylether sulfate were added to a 3 L glass reactor equipped with a thermometer, stirrer, dropping funnel, nitrogen gas inlet pipe and reflux condenser, followed by stirring. After replacing the inside of the reactor with nitrogen, the temperature was raised to 80 ° C. under a nitrogen atmosphere and maintained for 60 minutes.

Separately, in a 2 L beaker, 379 g of 2-ethyl hexylacrylate, 90 g of butyl acrylate, 60 g of methyl methacrylate, 61 g of vinyl acetate, 15 g of acrylic acid, and 0.6 g of normal-dodecylmercaptan as molecular weight modifier After adding, the mixture was stirred for 30 minutes to prepare a monomer mixture.

Here, a solution consisting of 20 g of sodium polyoxyethylene lauryl ether sulfate at a concentration of 26% by weight, 10 g of a solution of sodium alkyldiphenyloxide disulfonate at a concentration of 45% by weight, 2 g of sodium carbonate, and 180 g of water was added. and stirred to prepare a white turbid pre-emulsion.

3 g of ammonium persulfate having a concentration of 20% by weight was added to a glass reactor containing the emulsion and dissolved by stirring for 10 minutes.

The pre-emulsion and 102 g of ammonium persulfate at a concentration of 7% by weight were uniformly and continuously introduced into the glass reactor for 5 hours, and then polymerization was performed at 80° C. for 1 hour.

It was cooled to room temperature, and the pH was adjusted to 5-7 by adding a 10% by weight aqueous solution of sodium hydroxide to prepare an acrylic emulsion pressure-sensitive adhesive composition.

Comparative Example 2

An acrylic emulsion pressure-sensitive adhesive composition was prepared in the same manner as in Comparative Example 1, except that the content of 7% by weight of ammonium persulfate added together with the pre-emulsion was changed.

The contents are summarized in Table 2 below.

unit
(g) Comparative Example 1 Comparative Example 2 2-EHA 379 379 Vac 61 61 BA 90 90 MMA 60 60 AA 15 15 n-DDM 0.6 0.6 7% APS 102 25

* 2-EHA: 2-ethyl hexylacrylate; Vac: vinyl acetate; BA: butyl acrylate; MMA: methyl methacrylate; AA: acrylic acid; n-DDM: n-dodecylmercaptan; 7% APS: ammonium persulfate at a concentration of 7% by weight

Manufacture of adhesive members

The acrylic emulsion pressure-sensitive adhesive composition prepared above was coated on a release paper to a thickness of 20 μm, dried at 120 ° C. for 1 minute, and then laminated on a polypropylene film to prepare an adhesive member.

Physical properties of the above adhesive member were measured as follows.

Adhesion property measurement

1) 90 degree peel strength measurement

For the adhesive member prepared above, measure according to FTM 2 of the FINAT test method, prepare a specimen with a size of 1 inch x 20 cm, attach it on a stainless steel plate (SUS), It was compressed by reciprocating twice at a speed of min. 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.

2) How to measure shear

For the adhesive member prepared above, measure according to FTM 8 of the FINAT test method, prepare a specimen with a size of 1 inch x 20 cm, and attach it so that the stainless steel surface and the attachment surface are 1 inch x 0.5 inch. , and compressed by reciprocating twice with a 2 kg roller. After 10 minutes, the attached sheet was attached to a wall inclined by about 2 degrees, and a weight of 1000 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.

color measurement

For the adhesive member prepared above, the b value measured according to the CIE 1976 L*a*b* standard was measured using X-rite's Color-Eye 7000A, where the polypropylene film used as the substrate By subtracting the b value of , the b value of the acrylic emulsion pressure-sensitive adhesive composition itself was obtained. (b1)

After exposing the adhesive member at 70° C. for 3 hours, the b value of the acrylic emulsion pressure-sensitive adhesive composition itself was measured again in the same manner to find out the change. (b2)

The adhesive properties and color values measured above are summarized in Table 3 below.

peel strength
(N/in) retention
(1 in*0.5 in, 1 kg)
(Hr) Color, Δb b1 b2 Example 1 8 > 100 0.046 0.051 Example 2 7.6 > 100 0.064 0.094 Example 3 7.3 > 100 0.068 0.1 Example 4 6.7 > 100 0.065 0.093 Example 5 5.7 > 100 0.083 0.13 Example 6 5.1 > 100 0.077 0.217 Comparative Example 1 7.7 > 100 0.587 0.669 Comparative Example 2 6.2 > 100 0.268 0.351

Referring to Table 3, it can be seen that the acrylic emulsion pressure-sensitive adhesive composition according to the examples of the present application has excellent peel strength, excellent adhesive retention, and excellent colorlessness and transparency.

In particular, in the case of the comparative example, the b value according to the CIE 1976 L*a*b* standard is about 0.27 and about 0.59, so it can be seen that the index value not only comes out high from the beginning, but also increases significantly after exposure to the external environment.

However, in the case of the embodiment, it can be seen that all of the initial values are 0.1 or less, and even after being exposed to the external environment, the values are maintained at 0.1 or less, except for some.

Claims (15)

For all monomer-derived repeating units constituting the emulsion polymer,
A) 90 to 98 mol% of a repeating unit derived from a (meth)acrylic ester first monomer containing a chain alkyl group having 1 to 10 carbon atoms; and
B) 2 to 10 mol% of repeating units derived from at least one monomer selected from the group consisting of b1) an unsaturated carboxylic acid-based second monomer and b2) an aromatic vinyl-based third monomer;
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 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,
A) 94 to 97 mol% of a repeating unit derived from a (meth)acrylic ester-based first monomer containing a chain alkyl group having 1 to 10 carbon atoms; and
B) b1) an unsaturated carboxylic acid-based second monomer and b2) an acrylic emulsion pressure-sensitive adhesive composition comprising an emulsion polymer composed of 3 to 6 mol% of repeating units derived from at least one monomer selected from the group consisting of an aromatic vinyl-based third monomer .
For all monomer components,
A) 90 to 98 mol% of a (meth)acrylic ester-based first monomer containing a chain alkyl group having 1 to 10 carbon atoms;
B) 2 to 10 mol% of a monomer mixture of at least one monomer selected from the group consisting of b1) an unsaturated carboxylic acid-based second monomer and b2) an aromatic vinyl-based third monomer;
polymerization initiators; and
Including the step of emulsion polymerization of a composition for polymerization containing an emulsifier,
Method for producing an acrylic emulsion pressure-sensitive adhesive composition.
According to claim 6,
The emulsifier, a method for producing an acrylic emulsion pressure-sensitive adhesive composition comprising at least one selected from the group consisting of anionic emulsifiers, cationic emulsifiers, and nonionic emulsifiers.
According to claim 7,
The anionic emulsifier is sodium alkyl diphenyl ether disulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene aryl ether sulfate, sodium alkyl sulfate, sodium alkyl benzene sulfonate, and dialkyl sodium sulfosuccinate. Method for producing an acrylic emulsion pressure-sensitive adhesive composition comprising at least one selected from the group consisting of.
According to claim 7,
The nonionic emulsifier is a method for producing an acrylic emulsion pressure-sensitive adhesive composition comprising at least one selected from the group consisting of polyethylene oxide alkyl aryl ethers, polyethylene oxide alkyl amines, and polyethylene oxide alkyl esters.
According to claim 6,
The emulsifier is used in an amount of 0.01 to 10 parts by weight based on 100 parts by weight of the monomer component, a method for producing an acrylic emulsion pressure-sensitive adhesive composition.
According to claim 6,
The method for producing an acrylic emulsion pressure-sensitive adhesive composition, wherein the composition for polymerization further comprises an aqueous solvent.
transparent substrate;
A pressure-sensitive adhesive layer formed of the acrylic emulsion pressure-sensitive adhesive composition according to claim 1 on at least one surface of the transparent substrate,
no adhesive.
According to claim 12,
The adhesive layer has a b value of 0.1 or less measured according to the CIE 1976 L*a*b* standard.
According to claim 12,
The adhesive layer has a b value of 0.25 or less, measured according to the CIE 1976 L * a * b * standard, after exposure at 70 ° C. for 3 hours.
According to claim 12,
FINAT TEST METHOD NO. 2 An adhesive member with a 90 degree peel strength of 5 N/in or more, measured according to the standard.