KR20150012418A - Acrylic Emulsion Pressure Sensitive Adhesive And Method For Preparing The Same - Google Patents

Abstract

The present invention relates to an acrylic emulsion adhesive comprising latex particles, the adhesive including a (metha)acrylic acid ester monomer having a C_1-C_14 alkyl group as a main monomer; one or more types of monomers selected from a group consisting of allyl ester, vinyl ester, unsaturated acetate, and unsaturated nitrile as minor monomers; an unsaturated monomer having unsaturated carboxylic acid and a hydroxyl group as a functional monomer; and a crosslinking agent, wherein the latex particles have the concentration gradient in which the content of unsaturated carboxylic acid is consecutively increased from the center to the outermost part, and to a manufacturing method thereof.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acrylic emulsion pressure-

The present invention relates to an acrylic emulsion pressure-sensitive adhesive and a method for producing the same.

Pressure-Sensitive Adhesive (PSA) is a semi-solid material with a property of adhering to adherend with a small pressure. It is a viscoelastic material different from adhesive and has basic properties of initial adhesion, cohesion and cohesion. Trademark, advertisement, as well as printing, chemicals, pharmaceuticals, household appliances, automobiles, and stationery.

The pressure-sensitive adhesives can be classified into an acrylic type, a rubber type, a silicone type, an EVA type and the like depending on the monomers used in the production, and can be classified into a solvent type, an emulsion type and a hot-melt type depending on the form.

In the past, most of the pressure sensitive adhesives used in adhesive tapes and adhesive labels were rubber pressure sensitive adhesives and solvent pressure sensitive adhesives. However, as demand for environmentally friendly pressure sensitive adhesives increased, interest and technology development for pressureless pressure sensitive adhesives was progressed. Currently, development of pressureless pressure sensitive adhesives And production volume have increased greatly, and it is going to continue to increase in the future. The solventless pressure-sensitive adhesive is typically polymerized by aqueous emulsion polymerization.

Open Patent Publication No. 10-2011-0007373 and Open Patent Publication No. 10-2011-0075893 disclose a resin composition which is excellent in room temperature and aging tackiness and dimensional stability and has a high adhesion force close to that of a permanent adhesive, Discloses an acrylic pressure-sensitive adhesive and a method for producing the same. The foregoing prior art documents disclose re-peelable acrylic pressure-sensitive adhesives comprising latex particles having no compositional change from the center to the outermost layer.

The latex particles disclosed in the above-mentioned prior art and having no compositional change from the center to the outermost have a disadvantage in that the viscosity change during neutralization and storage is large and the effect of improving the physical properties is insufficient.

Disclosed is an acrylic emulsion pressure-sensitive adhesive which minimizes viscosity change during neutralization and storage, has a small amount of aggregates, and is excellent in initial adhesive force and peel strength, and a method for producing the same.

A non-limiting example of the acrylic emulsion pressure-

(Meth) acrylic acid ester monomers having a C ₁ -C ₁₄ alkyl group as a main monomer;

One or more monomers selected from the group consisting of allyl esters, vinyl esters, unsaturated acetates and unsaturated nitriles as minor monomers;

A monomer having an unsaturated carboxylic acid and a hydroxyl group as a functional monomer; And

A latex particle comprising a cross-linking agent,

The latex particles may have a concentration gradient in which the content of unsaturated carbonic acid increases continuously from the center to the outermost part.

The acrylic emulsion adhesive according to a non-limiting example of the present invention can be produced by a known suspension polymerization method, emulsion polymerization method, seed polymerization method or the like using known polymerization initiators, crosslinking agents, molecular weight regulators, emulsifiers and the like.

An acrylic emulsion pressure-sensitive adhesive according to a non-limiting example of the present invention can be produced by a method including the following steps (i) to (v). The above (i) to (v) are for distinguishing the respective processes, and the order is not determined by them.

(i) may be a process for preparing an emulsion containing a first emulsifier and water separately from a process for preparing two or more kinds of pre-emulsions. The content of the first emulsifier may be in the range of 0.5 to 1.5 parts by weight based on the total weight of the total monomers. In a non-limiting example of the present invention, the first emulsifier may comprise one or more emulsifiers.

The process (ii) may be a process for independently preparing two or more kinds of pre-emulsions each containing a main monomer, a minor monomer, a functional monomer, a crosslinking agent, a second emulsifier, and water and having different compositions. In a non-limiting example of the present invention, the two or more pre-emulsions may differ in the content of functional monomers. In this specification, the two or more kinds of pre-emulsions can be classified into a first pre-emulsion and a second pre-emulsion for convenience of explanation, and in a non-limiting example, the first pre- The content of the functional monomer may be relatively small.

In a non-limiting example of the present invention, the step (ii) may be a process of independently producing two kinds of pre-emulsions. At this time, the weight ratio of the monomers of the first pre-emulsion and the second pre-emulsion may be in the range of 20:80 to 80:20. As can be seen from the following experimental results, when the content of the monomers of the second pre-emulsion is more than 80% by weight based on the total weight of all the monomers, the viscosity change after neutralization is large and the cohesive force is insufficient. When the content of the monomers of the second pre-emulsion is less than 20% by weight based on the total weight, a large amount of agglomerates are generated and a phenomenon that initial adhesion is insufficient occurs.

The content of the second emulsifier may be 0.1 to 5 parts by weight based on the total weight of the total monomers. In a non-limiting example of the present invention, the second emulsifier may comprise two or more emulsifiers.

(iii) may be a step of continuously introducing the first polymerization initiator and two or more pre-emulsions into the emulsion continuously at an equal ratio. The content of the first polymerization initiator may be in the range of 0.1 to 5.0 parts by weight based on the total weight of the total monomers.

In the step (iii), the emulsion may contain a second polymerization initiator in a range of 0.01 to 0.5 parts by weight based on 100 parts by weight of the total monomers. That is, the second polymerization initiator may be contained before the first polymerization initiator and the two or more preemulsions are continuously introduced at an equal ratio.

In addition, the method may further include a step (iv) after the step (iii), and a step of adding the third polymerization initiator. The third polymerization initiator may be in a range of 0.01 part by weight to 0.5 part by weight based on the total weight of all monomers.

In addition, the method may further include the step of (iv) after the step (v), adjusting the pH to 6 or more to 9 or less, or 7 or more to 8 or less by using an alkaline substance. The alkaline substance may be an inorganic substance such as a hydroxide of a monovalent metal or a divalent metal, a chloride, a carbonate, or the like, ammonia, an organic amine, or the like.

The polymerization temperature and the polymerization time may be appropriately determined depending on the kind of the polymerization initiator and the like. For example, the polymerization temperature and the polymerization time may be from 0 to 100 캜, more specifically from 40 to 90 캜 in consideration of physical properties of the pressure- The time can be from 1 to 20 hours.

The main monomers are, but not limited to, the C ₁ -C a (meth) acrylic acid ester monomer with ₁₄ alkyl groups, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl ( (Meth) acrylate, butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl . ≪ / RTI > Preferably, it may be methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate or octyl (meth) acrylate.

Since the main monomer affects initial adhesion, it may be contained in the range of 70 wt% or more to 95 wt% or less based on the total mass of the total monomers. If it is less than 70% by weight, satisfactory initial adhesion can not be secured, which is not preferable.

The number of carbon atoms of the alkyl group may be from 1 to 14, and more specifically, from 2 to 14, and when the number is less than 1, the cohesive force of the acrylic emulsion pressure-sensitive adhesive is poor. When the number is more than 14, the acrylic emulsion pressure- And the adhesive property deteriorates, which is not preferable.

The minor monomers include, but are not limited to, vinyl acetate, vinyl butanoate, vinyl propionate, vinyl laurate, vinyl pyrrolidone, cyanogens fluoride, cyanogens chloride, acrylonitrile, methacryloyl Nitrile, and the like. Preferably, it may be acrylonitrile.

The minor monomer may be contained in the range of 4% by weight to 24% by weight based on the total weight of the total monomers since it affects the cohesive force of the pressure-sensitive adhesive by polymerization with the main monomer. When the amount is less than 4% by weight, the cohesive force is lowered to cause transfer upon peeling, and when it is more than 24% by weight, the adhesive strength is lowered.

(Meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxypropyl (meth) acrylate, and the like. (Meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, hydroxy octyl (meth) acrylate, hydroxy lauryl (meth) acrylate and hydroxypropyl glycol Preferably, it may be acrylic acid, methacrylic acid, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, or the like.

Since the functional monomer affects adhesion, cohesion, etc., the content may be in the range of 0.5 wt% or more to 5 wt% or less based on the total mass of all the monomers. When the amount is less than 0.5% by weight, the cohesive force is lowered and the transfer occurs during peeling, and when it is more than 5% by weight, the adhesive strength is lowered.

The crosslinking agent may be selected from, but not limited to, allyl methacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, hexanediol ethoxylate diacrylate, ethylene glycol Hexanediol ethoxylate diacrylate, neopentyl glycol ethoxylate diacrylate, neopentyl glycol propoxylate diacrylate, trimethylpropaneethoxylate triacrylate, trimethylolpropane triacrylate, And may be at least one member selected from the group consisting of trimethylolpropane triacrylate, trimethylolpropane triacrylate, pentaerythritol ethoxylate triacrylate, pentaerythritol propoxylate triacrylate, vinyltrimethoxysilane and divinylbenzene. Preferably, it may be allyl methacrylate, polyethylene glycol diacrylate, or the like.

The cohesive force and releasability can be improved by the addition of the crosslinking agent, and the preferable content can be within a range of 0.1 wt% or more to 3 wt% or less based on the total mass of the total monomers.

The first emulsifier and the second emulsifier can be sulfate, sulfonate, sulfosuccinate, carbonate, phosphate, and the like, and in a non-limiting example, sodium alkylsulfate, sodium polyoxyethylenesulfate, Sodium polyoxyethylene lauryl ether sulfate, sodium lauryl sulfate, sodium alkyl allyl sulfonate, sodium alkyl sulphonate, sodium alkyl ether sulphonate, sodium alkyl benzene sulphate, Sulfonate, sodium linear alkylbenzene sulfonate, sodium alpha-olefin sulfonate, sodium alcohol polyoxyethylene ether sulfonate, sodium dioctyl sulfosuccinate, sodium perfluorooctanesulfonate, sodium perfluoro sulfonate, Butane sulfonate, alkyl diphenyl oxide Sodium dioctyl sulfosuccinate (DOSS), sodium alkyl-aryl phosphate, sodium alkyl ether phos- tate, sodium lauroyl sarcosinate, sodium carbonate, ammonium carbonate, and the like. Lt; / RTI > However, the present invention is not limited thereto, and any known emulsifier may be included in the scope of the present invention.

The polymerization initiator may be a water-soluble polymerization initiator such as persulfate of ammonium or alkali metal, hydrogen peroxide, peroxide, hydroperoxide and the like, and may be used together with one or more reducing agents for emulsion polymerization reaction at low temperatures. The reducing agent may be sodium bisulfite, sodium metabisulfite, sodium hydrosulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbic acid, and the like.

Examples of the molecular weight regulator include mercaptans or terpines such as terbinol, dipentene and t-terpine; halogenated hydrocarbons such as chloroform and carbon tetrachloride; and the like.

A non-limiting example of the present invention can also provide a protective film formed by applying an aqueous adhesive containing the above acrylic emulsion pressure-sensitive adhesive onto one side or both sides of a paper or film label.

The present invention can provide an acrylic emulsion pressure-sensitive adhesive which minimizes viscosity change during neutralization and storage, has a small amount of aggregates, and has excellent initial adhesion and peeling strength.

Hereinafter, the present invention will be described in further detail with reference to the following examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

≪ Example 1 >

370 g of distilled water and 10 g of sodium polyoxyethylene lauryl ether sulfate as a surfactant were placed in a 3 L glass reactor equipped with a thermometer, a stirrer, a nitrogen gas introducing tube and a reflux condenser, and the inside of the reactor was purged with nitrogen After the substitution, the temperature was raised to 80 DEG C in a nitrogen atmosphere, and the temperature was maintained for 60 minutes.

Separately from the above emulsion preparation process, 165 g of butyl acrylate (BA), 482.5 g of 2-ethylhexyl acrylate (2-EHA), 62.5 g of vinyl acetate, 38 g of acrylonitrile, 1.5 g of glycol 400 diacrylate and 0.5 g of normal dodecyl mercaptan were added 12.5 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate, 7.5 g of 45% by weight of alkyl diphenyl oxide disulfonate, 5 g of sodium carbonate, 2.5 g of sodium methyl allylsulfonate and 187.5 g of distilled water was added and mixed with a stirrer to prepare a first pre-emulsion of white color.

Separately from the first pre-emulsion preparation, 165 g of butyl acrylate (BA), 437.5 g of 2-ethylhexyl acrylate (2-EHA), 62.5 g of vinyl acetate, 62.5 g of acrylonitrile , 45 g of acrylic acid, 1.5 g of polyethylene glycol 400 diacrylate and 0.5 g of normal dodecyl mercaptan were added 30.5% by weight of sodium polyoxyethylene lauryl ether sulfate, 12.5 g of 45% by weight of alkyl diphenyl oxide di A solution of 7.5 g of sulfonate, 5 g of sodium carbonate, 2.5 g of sodium methyl allyl sulfonate and 187.5 g of distilled water was added and mixed with a stirrer to prepare a second whitening emulsion.

10% by weight of ammonium persulfate and 10 g of ammonium sulfate were added to a glass reactor containing the emulsion and dissolved by stirring for 10 minutes.

The first pre-emulsion and 180 g of a 10 wt% ammonium persulfate aqueous solution were continuously fed into a glass reactor containing the emulsion, and the second pre-emulsion was continuously introduced into the first pre-emulsion, and a first pre-emulsion, ammonium persulfate Aqueous solution and 10 g of an aqueous ammonium sulfate solution were further added thereto and then the temperature was kept at 80 ° C. for 1 hour and then cooled to room temperature to obtain an emulsion acrylic resin .

A 28% by weight aqueous ammonia solution was added to the emulsion acrylic resin to adjust the pH to 7 to 8.

≪ Example 2 >

An acrylic emulsion pressure-sensitive adhesive was prepared in the same manner as in Example 1, except that the composition of the first pre-emulsion and the composition of the second pre-emulsion were changed as follows.

The first pre-emulsion

To prepare the first pre-emulsion, 66 g of butyl acrylate (BA), 193 g of 2-ethylhexyl acrylate (2-EHA), 25 g of vinyl acetate, 15.2 g of acrylonitrile, 0.6 g of polyethylene glycol 400 diacrylate, 5 g of sodium polyoxyethylene lauryl ether sulfate, 3 g of 45% by weight of alkyldiphenyl oxide disulfonate, 2 g of sodium carbonate, 1 g of sodium methyl allyl sulfonate, and 5 g of sodium dodecyl mercaptan were added to a monomer mixture containing 0.2 g of dodecylmercaptan And 75 g of distilled water was added and mixed with a stirrer to prepare a first pre-emulsion of white turbidity.

The second pre-emulsion

To prepare the second pre-emulsion, 264 g of butyl acrylate (BA), 727 g of 2-ethylhexyl acrylate (2-EHA), 100 g of vinyl acetate, 60.8 g of acrylonitrile, 45 g of acrylic acid, 2.4 g of sodium dodecyl mercaptan and 0.8 g of normal dodecyl mercaptan was added 20 g of 30 wt% sodium polyoxyethylene lauryl ether sulfate, 12 g of 45 wt% of alkyl diphenyl oxide disulfonate, 8 g of sodium carbonate, 4 g of sulfonate and 300 g of distilled water was added and mixed with a stirrer to prepare a second pre-emulsion of white turbidity.

≪ Example 3 >

An acrylic emulsion pressure-sensitive adhesive was prepared in the same manner as in Example 1, except that the composition of the first pre-emulsion and the composition of the second pre-emulsion were changed as follows.

The first pre-emulsion

To prepare the first pre-emulsion, 264 g of butyl acrylate (BA), 772 g of 2-ethylhexyl acrylate (2-EHA), 100 g of vinyl acetate, 60.8 g of acrylonitrile, 2.4 g of polyethylene glycol 400 diacrylate, 20 g of sodium polyoxyethylene lauryl ether sulfate, 12 g of 45% by weight of alkyldiphenyl oxide disulfonate, 8 g of sodium carbonate, 4 g of sodium methyl allyl sulfonate, and 10 g of sodium dodecyl mercaptan were added to a monomer mixture containing 0.8 g of n- And 300 g of distilled water was added and mixed with a stirrer to prepare a first pre-emulsion of white turbidity.

The second pre-emulsion

To prepare the second pre-emulsion, 66 g of butyl acrylate (BA), 148 g of 2-ethylhexyl acrylate (2-EHA), 25 g of vinyl acetate, 15.2 g of acrylonitrile, 45 g of acrylic acid and 150 g of polyethylene glycol 400 diacrylate And 0.2 g of normal dodecyl mercaptan were added 30 g of sodium polyoxyethylene lauryl ether sulfate 5 g, 45 g of alkyl diphenyl oxide disulfonate 3 g, sodium carbonate 2 g, sodium methyl ally sulfo 1 g of Nate and 75 g of distilled water was added and mixed with a stirrer to prepare a second pre-emulsion of a whitish white.

<Example 4>

An acrylic emulsion pressure-sensitive adhesive was prepared in the same manner as in Example 1, except that the composition of the first pre-emulsion and the composition of the second pre-emulsion were changed as follows.

The first pre-emulsion

To prepare the first pre-emulsion, 165 g of butyl acrylate (BA), 467.5 g of 2-ethylhexyl acrylate (2-EHA), 62.5 g of vinyl acetate, 38 g of acrylonitrile, 15 g of acrylic acid, 1.5 g of sodium dodecyl mercaptan and 0.5 g of normal dodecyl mercaptan were added 12.5 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate, 7.5 g of 45% by weight of alkyl diphenyl oxide disulfonate, 5 g of sodium carbonate, 2.5 g of methyl allylsulfonate and 187.5 g of distilled water was added thereto, followed by mixing with a stirrer to prepare a first pre-emulsion of white turbidity.

The second pre-emulsion

To prepare the second pre-emulsion, 165 g of butyl acrylate (BA), 497.5 g of 2-ethylhexyl acrylate (2-EHA), 62.5 g of vinyl acetate, 38 g of acrylonitrile, 30 g of acrylic acid, 1.5 g of sodium dodecyl mercaptan, and 0.5 g of normal dodecyl mercaptan was added 12.5 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate, 7.5 g of 45% by weight of alkyl diphenyl oxide disulfonate, 5 g of sodium carbonate, 2.5 g of methyl allylsulfonate and 187.5 g of distilled water was added and mixed with a stirrer to prepare a second pre-emulsion of whitish white.

&Lt; Example 5 >

An acrylic emulsion pressure-sensitive adhesive was prepared in the same manner as in Example 1, except that the composition of the second pre-emulsion was changed as follows.

The second pre-emulsion

To prepare the second pre-emulsion, 165 g of butyl acrylate (BA), 437.5 g of 2-ethylhexyl acrylate (2-EHA), 452.5 g of vinyl acetate, 38 g of acrylonitrile, 30 g of acrylic acid, 1.5 g of sodium dodecyl mercaptan, and 0.5 g of normal dodecyl mercaptan was added 12.5 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate, 7.5 g of 45% by weight of alkyl diphenyl oxide disulfonate, 5 g of sodium carbonate, 2.5 g of methyl allylsulfonate and 187.5 g of distilled water was added and mixed with a stirrer to prepare a second pre-emulsion of whitish white.

&Lt; Example 6 >

An acrylic emulsion pressure-sensitive adhesive was prepared in the same manner as in Example 1, except that the composition of the second pre-emulsion was changed as follows.

The second pre-emulsion

To prepare the second pre-emulsion, 165 g of butyl acrylate (BA), 475 g of 2-ethylhexyl acrylate (2-EHA), 62.5 g of vinyl acetate, 38 g of acrylonitrile, 7.5 g of acrylic acid, 1.5 g of sodium dodecyl mercaptan, and 0.5 g of normal dodecyl mercaptan was added 12.5 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate, 7.5 g of 45% by weight of alkyl diphenyl oxide disulfonate, 5 g of sodium carbonate, 2.5 g of methyl allylsulfonate and 187.5 g of distilled water was added and mixed with a stirrer to prepare a second pre-emulsion of whitish white.

&Lt; Example 7 >

An acrylic emulsion pressure-sensitive adhesive was prepared in the same manner as in Example 1, except that the composition of the second pre-emulsion was changed as follows.

The second pre-emulsion

To prepare the second pre-emulsion, 165 g of butyl acrylate (BA), 407.5 g of 2-ethylhexyl acrylate (2-EHA), 62.5 g of vinyl acetate, 38 g of acrylonitrile, 75 g of acrylic acid, 1.5 g of sodium dodecyl mercaptan, and 0.5 g of normal dodecyl mercaptan was added 12.5 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate, 7.5 g of 45% by weight of alkyl diphenyl oxide disulfonate, 5 g of sodium carbonate, 2.5 g of methyl allylsulfonate and 187.5 g of distilled water was added and mixed with a stirrer to prepare a second pre-emulsion of whitish white.

&Lt; Comparative Example 1 &

An acrylic emulsion pressure-sensitive adhesive was prepared in the same manner as in Example 1, except that the pre-emulsion prepared as described below was added to a glass reactor containing an emulsion.

Pre emulsion

To the beaker was added 330 g of butyl acrylate (BA), 920 g of 2-ethylhexyl acrylate (2-EHA), 125 g of vinyl acetate, 76 g of acrylonitrile, 45 g of acrylic acid, 3 g of polyethylene glycol 400 diacrylate and 1 g of normal dodecyl mercaptan To the mixed monomer mixture, a solution composed of 25 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate, 15 g of 45% by weight of alkyldiphenyl oxide disulfonate, 10 g of sodium carbonate, 5 g of sodium methylallylsulfonate and 375 g of distilled water was added And the mixture was mixed with a stirrer to prepare a white emulsion pre-emulsion.

&Lt; Comparative Example 2 &

In Example 1, the first pre-emulsion was put into a glass reactor without continuously injecting the polymerization initiator, the first pre-emulsion and the second pre-emulsion in an equal ratio for 4 hours, Lt; / RTI &gt; Except for this, an acrylic emulsion pressure-sensitive adhesive was prepared in the same manner as in Example 1.

&Lt; Comparative Example 3 &

The first pre-emulsion, the second pre-emulsion and the third pre-emulsion, which were prepared as described below, were continuously introduced into the glass reactor in the following manner, without continuously feeding the polymerization initiator, the first pre-emulsion and the second pre- Respectively. Except for this, an acrylic emulsion pressure-sensitive adhesive was prepared in the same manner as in Example 1.

The first pre-emulsion

To prepare the first pre-emulsion, 109 g of butyl acrylate (BA), 321.6 g of 2-ethylhexyl acrylate (2-EHA), 41.6 g of vinyl acetate, 25.3 g of acrylonitrile, 1 g of polyethylene glycol 400 diacrylate And 0.33 g of normal dodecylmercaptan were mixed, 8.3 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate, 5 g of 45% by weight of alkyldiphenyl oxide disulfonate, 3.3 g of sodium carbonate, 1.66 g of Nate and 125 g of distilled water was added thereto and mixed with a stirrer to prepare a first pre-emulsion of a cloudy white color.

The second pre-emulsion

To prepare the second pre-emulsion, 109 g of butyl acrylate BA, 306.6 g of 2-ethylhexyl acrylate (2-EHA), 41.6 g of vinyl acetate, 25.3 g of acrylonitrile, 15 g of acrylic acid, Acrylate, and 0.33 g of normal dodecyl mercaptan was added to the monomer mixture, to which 8.3 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate, 5 g of 45% by weight of alkyldiphenyl oxide disulfonate, 3.3 g of sodium carbonate, 1.66 g of methyl allylsulfonate and 125 g of distilled water was added and mixed with a stirrer to prepare a second free pre-emulsion.

The third pre-emulsion

To prepare the third pre-emulsion, 110 g of butyl acrylate (BA), 291.8 g of 2-ethylhexyl acrylate (2-EHA), 41.8 g of vinyl acetate, 25.4 g of acrylonitrile, 30 g of acrylic acid, Acrylate, and 0.34 g of normal dodecyl mercaptan was mixed with 8.4 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate, 5 g of 45% by weight of alkyldiphenyl oxide disulfonate, 3.4 g of sodium carbonate, 1.68 g of methyl allylsulfonate, and 125 g of distilled water was added and mixed with a stirrer to prepare a third pre-emulsion of white turbidity.

&Lt; Comparative Example 4 &

An acrylic emulsion pressure-sensitive adhesive was prepared in the same manner as in Example 1 except that the first pre-emulsion and the second pre-emulsion were respectively prepared as follows.

The first pre-emulsion

To prepare the first pre-emulsion, 165 g of butyl acrylate (BA), 437.5 g of 2-ethylhexyl acrylate (2-EHA), 62.5 g of vinyl acetate, 38 g of acrylonitrile, 45 g of acrylic acid, 1.5 g of sodium dodecyl mercaptan and 0.5 g of normal dodecyl mercaptan were added 12.5 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate, 7.5 g of 45% by weight of alkyl diphenyl oxide disulfonate, 5 g of sodium carbonate, 2.5 g of methyl allylsulfonate and 187.5 g of distilled water was added thereto, followed by mixing with a stirrer to prepare a first pre-emulsion of white turbidity.

The second pre-emulsion

To prepare the second pre-emulsion, 165 g of butyl acrylate (BA), 482.5 g of 2-ethylhexyl acrylate (2-EHA), 62.5 g of vinyl acetate, 38 g of acrylonitrile, 1.5 g of polyethylene glycol 400 diacrylate And 0.5 g of normal dodecylmercaptan were mixed, 12.5 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate, 7.5 g of 45% by weight of alkyldiphenyl oxide disulfonate, 5 g of sodium carbonate, 2.5 g of sodium acetate and 187.5 g of distilled water was added and mixed with a stirrer to prepare a second free pre-emulsion.

&Lt; Comparative Example 5 &

An acrylic emulsion pressure-sensitive adhesive was prepared in the same manner as in Example 1 except that the first pre-emulsion and the second pre-emulsion were respectively prepared as follows.

The first pre-emulsion

To prepare the first pre-emulsion, 49.5 g of butyl acrylate (BA), 144.8 g of 2-ethylhexyl acrylate (2-EHA), 18.75 g of vinyl acetate, 11.4 g of acrylonitrile, And 0.15 g of normal dodecyl mercaptan were added to a monomer mixture containing 3.75 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate, 2.25 g of 45% by weight of alkyl diphenyl oxide disulfonate, 1.5 g of sodium carbonate, 0.75 g of methyl allylsulfonate and 56.25 g of distilled water was added and mixed with a stirrer to prepare a first pre-emulsion of white turbidity.

The second pre-emulsion

To prepare the second pre-emulsion, 280.5 g of butyl acrylate (BA), 775.2 g of 2-ethylhexyl acrylate (2-EHA), 106.25 g of vinyl acetate, 64.6 g of acrylonitrile, 45 g of acrylic acid, 2.55 g of diacrylate, and 0.85 g of normal dodecyl mercaptan was added 21.25 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate, 12.75 g of 45% by weight of alkyl diphenyl oxide disulfonate, sodium carbonate 8.5 g, sodium methylallylsulfonate (4.25 g), and distilled water (318.75 g) were charged and mixed with a stirrer to prepare a second whitening emulsion.

&Lt; Comparative Example 6 >

An acrylic emulsion pressure-sensitive adhesive was prepared in the same manner as in Example 1 except that the first pre-emulsion and the second pre-emulsion were respectively prepared as follows.

The first pre-emulsion

To prepare the first pre-emulsion, 280.5 g of butyl acrylate (BA), 820.2 g of 2-ethylhexyl acrylate (2-EHA), 106.25 g of vinyl acetate, 64.6 g of acrylonitrile, 150 g of polyethylene glycol 400 diacrylate And 0.85 g of normal dodecyl mercaptan were added 21.25 g of sodium polyoxyethylene lauryl ether sulfate in an amount of 30% by weight, 12.75 g of 45% by weight of alkyl diphenyl oxide disulfonate, 8.5 g of sodium carbonate, 4.25 g of methyl allylsulfonate and 318.75 g of distilled water was added and mixed with a stirrer to prepare a first pre-emulsion of white turbidity.

The second pre-emulsion

To prepare the second pre-emulsion, 49.5 g of butyl acrylate (BA), 99.8 g of 2-ethylhexyl acrylate (2-EHA), 18.75 g of vinyl acetate, 11.4 g of acrylonitrile, 45 g of acrylic acid, 0.45 g of diacrylate and 0.15 g of normal dodecyl mercaptan were added 30% by weight sodium polyoxyethylene lauryl ether sulfate 3.75 g, 45% by weight of alkyl diphenyl oxide disulfonate 2.25 g, sodium carbonate 1.5 g, sodium methylallylsulfonate (0.75 g) and distilled water (56.25 g), and the mixture was stirred with a stirrer to prepare a second pre-emulsion.

&Lt; Comparative Example 7 &

An acrylic emulsion pressure-sensitive adhesive was prepared in the same manner as in Example 1, except that the second pre-emulsion was prepared as follows.

The second pre-emulsion

To prepare the second pre-emulsion, 165 g of butyl acrylate (BA), 476.5 g of 2-ethylhexyl acrylate (2-EHA), 62.5 g of vinyl acetate, 38 g of acrylonitrile, 6 g of acrylic acid, 1.5 g of sodium dodecyl mercaptan, and 0.5 g of normal dodecyl mercaptan was added 12.5 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate, 7.5 g of 45% by weight of alkyl diphenyl oxide disulfonate, 5 g of sodium carbonate, 2.5 g of methyl allylsulfonate and 187.5 g of distilled water was added and mixed with a stirrer to prepare a second pre-emulsion of whitish white.

&Lt; Comparative Example 8 >

An acrylic emulsion pressure-sensitive adhesive was prepared in the same manner as in Example 1, except that the second pre-emulsion was prepared as follows.

The second pre-emulsion

To prepare the second pre-emulsion, 165 g of butyl acrylate (BA), 400 g of 2-ethylhexyl acrylate (2-EHA), 62.5 g of vinyl acetate, 38 g of acrylonitrile, 82.5 g of acrylic acid, 1.5 g of sodium dodecyl mercaptan, and 0.5 g of normal dodecyl mercaptan was added 12.5 g of 30% by weight sodium polyoxyethylene lauryl ether sulfate, 7.5 g of 45% by weight of alkyl diphenyl oxide disulfonate, 5 g of sodium carbonate, 2.5 g of methyl allylsulfonate and 187.5 g of distilled water was added and mixed with a stirrer to prepare a second pre-emulsion of whitish white.

<Experimental Example 1>

The adhesive properties, agglomerate content, initial adhesion, peel strength and cohesion of the acrylic emulsion pressure-sensitive adhesives prepared in the above Examples and Comparative Examples were measured by the following methods, and the results are shown in Table 1.

Viscosity measurement

And measured using a Brookfield DV-III Ultra viscometer. The measurement conditions were 25 deg. C, Spindle No. LV3, 12 rpm.

Measurement of aggregate content

100 g of the acrylic emulsion pressure-sensitive adhesive was filtered using a standard having a scale size of 74 탆 according to the process standard, washed with distilled water until the water flowing down the filtered aggregate became transparent, and then dried at a temperature of 110 캜 or lower. The weight of the dried residue and the weight before drying were measured and the aggregate content was calculated using the following equation.

Content of aggregate (%) = {(weight before drying) - (weight after drying) / weight after drying} × 100

<Experimental Example 2>

The acrylic emulsion pressure sensitive adhesive prepared in the above Examples and Comparative Examples was coated on a release paper coated with silicone and dried in an oven at 120 캜 for 1 minute to have an acryl pressure sensitive adhesive resin layer having a thickness of 20 탆. This paper was laminated with paper to make a paper label and cut into a size of 1 inch x 100 mm to prepare a paper label specimen.

Initial Loop Tack Measurement Method :

Test method FINAT TEST METHOD No. 9, the paper label specimens were annularized and attached to the glass surface with no pressure applied, and measured for 5 seconds using a TA Texture Analyzer at a rate of 300 mm / min (unit: N / in).

Peel strength test

Test method FINAT TEST METHOD No. 2, the paper label specimen was reciprocated twice on a glass plate at a speed of 2 kg roller at a speed of 300 mm / min, aged at room temperature for 20 minutes, and then peeled off at 90 mm at a speed of 300 mm / min using a TA Texture Analyzer (Unit: N / in).

Cohesion test

Test method FINAT TEST METHOD No. 8, the paper label specimens were attached to a stainless steel surface (SUS 304) so that the attached surface was 1 × 1 inch. Then, they were kept in a 70 ° C. oven for 30 minutes while holding them in a weight of 500 g. And cooled. Thereafter, a weight of 1 kg was applied to the end of the specimen, and the additional dropping time was measured.

division Monomer content Polymerization method Acrylic acid content (% by weight) The first pre-emulsion / second pre-emulsion The first pre-emulsion /
The second pre-emulsion Content of total acrylic acid Example 1 50/50 Gradient 0/3 3 Example 2 20/80 Gradient 0/3 3 Example 3 80/20 Gradient 0/3 3 Example 4 50/50 Gradient 1/2 3 Example 5 50/50 Gradient 0/2 2 Example 6 50/50 Gradient 0 / 0.5 0.5 Example 7 50/50 Gradient 0/5 5 Comparative Example 1 100/0 Stage 1 3/0 3 Comparative Example 2 50/50 Step 2 0/3 3 Comparative Example 3 33/33/34 Step 3 0/1/2 3 Comparative Example 4 50/50 Gradient 3/0 0 Comparative Example 5 15/85 Gradient 0/3 3 Comparative Example 6 85/15 Gradient 0/3 3 Comparative Example 7 50/50 Gradient 0 / 0.4 0.4 Comparative Example 8 50/50 Gradient 0 / 5.5 5.5

division Viscosity (cps) Agglomerate
Content (ppm) Early
Adhesion (N / in) 90 占 Peeling force (N / in) cohesion
(minute) After 1 hour After 7 days Example 1 1100 900 500 18 8 1100 Example 2 1050 800 470 18 8 1000 Example 3 1250 1100 550 17 9 1250 Example 4 1050 850 500 17 8 1050 Example 5 900 800 450 19 7 890 Example 6 800 750 510 20 9 570 Example 7 1250 1000 500 17 7 1700 Comparative Example 1 1050 700 500 17 7 800 Comparative Example 2 1100 800 1200 16 8 900 Comparative Example 3 1050 800 1100 17 8 930 Comparative Example 4 900 500 1500 17 6 700 Comparative Example 5 1000 700 500 17 7 850 Comparative Example 6 1200 1100 2000 15 7 1200 Comparative Example 7 700 600 590 20 8 390 Comparative Example 8 1200 1000 800 15 6 2000

Referring to Table 2, it can be seen that Examples 1 to 7 exhibit less change in viscosity before and after neutralization, good stability during polymerization, small aggregate formation, and excellent physical properties including cohesive force.

In Comparative Example 1, the viscosity change before and after neutralization was large and the effect of improving the physical properties was insufficient. In Comparative Example 2, the change in viscosity before and after neutralization was smaller than that in single polymerization in Comparative Example 2, Is insufficient. Comparative Example 3 shows that although the viscosity change before and after neutralization is smaller than that of the single and the two-stage polymerization in the three-stage polymerization, the viscosity change is larger than those of the embodiments in which the gradient polymerization is also performed and the polymerization steps are cumbersome, have.

In the case of Comparative Example 4, the gradient polymerization method was used as in the Example, but it was used in the acrylic acid 1 pre-emulsion, so that the change in viscosity before and after neutralization was large and the peeling force and cohesive force were low.

Comparative Examples 5 and 6 are examples in which the weight ratios of the monomers of the first pre-emulsion and the second pre-emulsion do not satisfy, and based on the total weight of all the monomers, the content of the monomers of the second pre- When the content of the monomers of the second pre-emulsion is less than 20% by weight based on the total weight of all the monomers, a large amount of agglomerates are generated and an initial adhesion strength It can be confirmed that the deficiency phenomenon occurs.

In Comparative Examples 7 and 8, the gradient polymerization method was used. However, when the content is out of the total acrylic acid content range, it is found that the aggregation is somewhat large and the initial adhesive force and peeling force are low. , Indicating that the cohesive force is insufficient.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims (14)

(Meth) acrylic acid ester monomers having a C ₁ -C ₁₄ alkyl group as a main monomer;
One or more monomers selected from the group consisting of allyl esters, vinyl esters, unsaturated acetates and unsaturated nitriles as minor monomers;
Unsaturated monomers having an unsaturated carboxylic acid and a hydroxyl group as functional monomers; And
A latex particle comprising a cross-linking agent,
Wherein the latex particles have a concentration gradient in which the content of unsaturated carbonic acid continuously increases from the center to the outermost part. The method according to claim 1,
Wherein the main monomer has a content in the range of from 70% by weight to 95% by weight, based on the total weight of the total monomers, and the minor monomer content is from 4% by weight to 24% by weight, Wherein the content of the functional monomer is in the range of 0.5 wt% to 5 wt% based on the total weight of all the monomers, and the content of the crosslinking agent is in the range of , And is in the range of 0.1 wt% or more to 3 wt% or less. The method of claim 1 wherein the C ₁ -C a (meth) acrylic acid ester monomer with ₁₄ alkyl groups, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate (Meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl Acrylic emulsion adhesive. The positive resist composition according to claim 1, wherein the at least one monomer selected from the group consisting of the allyl ester, the vinyl ester, the unsaturated acetate and the unsaturated nitrile,
Acrylic acid, vinyl acetate, vinyl butanoate, vinyl propionate, vinyl laurate, vinyl pyrrolidone, cyanogens fluoride, cyanogens chloride, acrylonitrile and methacrylonitrile. Emulsion Adhesive. The composition according to claim 1, wherein the unsaturated carboxylic acid and the monomer having a hydroxyl group are selected from the group consisting of maleic anhydride, fumaric acid, crotonic acid, itaconic acid, and acrylic acid, methacrylic acid, hydroxyethyl (meth) acrylate, (Meth) acrylate, hydroxypropyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl Based on the weight of the acrylic emulsion. The method according to claim 1, wherein the crosslinking agent is selected from the group consisting of allyl methacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, hexanediol ethoxylate diacrylate, Ethylene glycol diacrylate, ethylene glycol dimethacrylate, hexanediol ethoxylate diacrylate, hexanediol propoxylate diacrylate, neopentyl glycol ethoxylate diacrylate, neopentyl glycol propoxylate diacrylate, trimethylpropaneethoxylate Wherein the acrylic emulsion is at least one selected from the group consisting of triacrylate, trimethylolpropane propoxylate triacrylate, pentaerythritol ethoxylate triacrylate, pentaerythritol propoxylate triacrylate, vinyltrimethoxysilane and divinylbenzene. adhesive. A protective film formed by applying an aqueous pressure-sensitive adhesive comprising an acrylic emulsion pressure-sensitive adhesive according to any one of claims 1 to 6 on one side or both sides of a film. A process for producing the acrylic emulsion pressure-sensitive adhesive according to claim 1,
(i) preparing an emulsion containing a first emulsifier and water separately from the production of the following two or more pre-emulsions;
(ii) preparing two or more preemulsions each containing a main monomer, a minor monomer, a functional monomer, a crosslinking agent, a second emulsifier, and water and having different compositions from each other;
(iii) continuously injecting the first polymerization initiator and at least two kinds of pre-emulsions into the emulsion in an equal ratio;
(iv) heating the resulting product of step (iii) by heating and adding an alkaline substance at room temperature to adjust the pH to a range of 6 or more to 9 or less;
Wherein the acrylic emulsion pressure-sensitive adhesive is prepared by a method comprising the steps of: 9. The method of claim 8,
Wherein the content of the first polymerization initiator in the step (iii) ranges from 0.1 part by weight to 5.0 parts by weight based on 100 parts by weight of the total monomers. 9. The method of claim 8,
Further comprising a step of adding a second polymerization initiator to the emulsion in the range of from 0.01 part by weight to 0.5 part by weight based on 100 parts by weight of the total monomers before the step (iii) &Lt; / RTI &gt; 9. The method of claim 8,
The method may further include, before the step (iv), further comprising the step of adding a third polymerization initiator to the resultant product (iii) in an amount of 0.01 part by weight to 0.5 part by weight based on 100 parts by weight of all the monomers By weight based on the total weight of the acrylic emulsion pressure-sensitive adhesive. 9. The method of claim 8,
The step (ii) is a process for preparing two types of pre-emulsions,
Wherein the two types of pre-emulsions are composed of a first pre-emulsion having a small content of functional monomers and a second pre-emulsion having a relatively large content of functional monomers. 9. The method of claim 8,
Wherein the first emulsifier is composed of one or more emulsifiers and the second emulsifier comprises two or more kinds of emulsifiers. The acrylic emulsion pressure-sensitive adhesive of claim 8, wherein the amount of the second emulsifier is 0.1 to 5 parts by weight based on 100 parts by weight of the total monomers.