KR101725892B1 - Acrylic Emulsion Adhesive with Excellent Detergency and Preparation Method Thereof - Google Patents

Abstract

The present invention relates to an acrylic emulsion pressure-sensitive adhesive excellent in washability and a method for producing the acrylic pressure-sensitive adhesive, which comprises an unmelted polymerized seed of 1 to 10% by weight of an acrylic monomer mixture based on the total weight of the acrylic monomer mixture, The present invention relates to an acrylic emulsion pressure-sensitive adhesive and a method for producing the same, wherein the acrylic-based monomer mixture contains an acrylic-based emulsion resin emulsion-polymerized and the seed is wrapped by an acrylic-based emulsion resin.

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 excellent in washability 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 adhesive may 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 may be classified into a solvent type, an emulsion type and a hot-

In the past, most of the pressure sensitive adhesives used in adhesive tapes and adhesive labels were rubber pressure sensitive adhesives or solvent pressure sensitive adhesives. However, as demand for environmentally friendly pressure sensitive adhesives increased, attention and technology development for pressureless pressure sensitive adhesives was progressing. The development and production volumes have increased greatly and are steadily increasing. Such a solventless pressure-sensitive adhesive is typically polymerized by aqueous emulsion polymerization.

The water-based emulsion pressure-sensitive adhesive can use a polymer having a higher molecular weight than that of the solvent-based polymer because the viscosity of the pressure-sensitive adhesive is independent of the molecular weight of the dispersion polymer, and the concentration range of the solid content can be widely obtained. It has good adhesiveness in a solid content region and has good compatibility with other polymers.

However, since water is used as a solvent, there is a problem that the drying speed is slow, the adhesiveness to the hydrophobic adhesive surface and the non-porous adhesive agent is low, the selection range of the curing agent is narrow and the initial adhesive force is low, And a dispersant, and therefore, it has a low water resistance and can not reach the physical properties as the oil-based pressure-sensitive adhesive.

On the other hand, the polymerization method for producing the resin of the acrylic emulsion pressure-sensitive adhesive is divided into a solution type and an emulsion polymerization type.

Among them, the solution type is advantageous in that it is easy to control the reaction conditions of the polymerization and efficiently produce a homogeneous polymer. However, since the solvent is used, the molecular weight of the polymer is lower than other polymerization methods and the polymerization rate is slow. There is a limitation in that a chain transfer by the chain transfer is inevitable and a solvent which causes chain transfer as little as possible is used.

On the other hand, the emulsion polymerization type is economical because it has a large affinity to water and does not require a post-treatment process, the reaction is terminated within a few hours and the conversion rate is close to 100%. Acrylic emulsion pressure sensitive adhesives are manufactured through emulsion polymerization instead of solution type have.

However, when the particle size of the water based emulsion pressure sensitive adhesive synthesized by the above emulsion polymerization type is too large or small, stability is not sufficient, resulting in generation of agglomerates, resulting in deterioration of physical properties.

In recent years, there has been a growing demand for recycled resources and eco-friendly products. In order to recycle the adhesive material or sheet after using the water-based emulsion pressure-sensitive adhesive or acrylic emulsion pressure-sensitive adhesive, Or an additional process of removing the sheet from the adherend is necessarily required. However, at present, there is a problem that not only the removal takes much time but also the recycling of the adherend itself is impossible. Therefore, in order to completely remove the film or sheet from the adherend and to reduce the time required therefor, there is a high demand for an excellent effect as cleaner and adhesiveness.

However, the conventional water-based emulsion pressure-sensitive adhesives synthesized by the above emulsion polymerization type have problems such as small size of particles and difficulty in washing because of wide distribution of particles, resulting in deterioration of washing ability as a whole.

Accordingly, there is a high need for a technique for an acrylic emulsion pressure-sensitive adhesive exhibiting excellent adhesive property and excellent washing property.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and the technical problems required from the past.

The inventors of the present application have conducted intensive research and various experiments, and have found that a seed obtained by emulsion-polymerizing an acrylic monomer mixture is first prepared, and an acryl-based emulsion pressure-sensitive adhesive is prepared by mixing and emulsion- , It has been confirmed that the final particles of the acrylic emulsion pressure-sensitive adhesive have an appropriate size and are uniform so that they have excellent adhesive properties and are easy to wash with water, and have completed the present invention.

Accordingly, the acrylic emulsion pressure-sensitive adhesive according to the present invention comprises a seed obtained by emulsion-polymerizing an acrylic monomer mixture in an amount of 1 to 10% by weight based on the total weight of the acrylic monomer mixture, and an acrylic monomer mixture in an amount of 90 to 99% An emulsion-polymerized acrylic emulsion resin, and the seed is surrounded by an acrylic emulsion resin.

As used herein, the term " monomer mixture ", as used herein, refers to a mixture of monomers described below, based on acrylic monomers, mixed together and prepared, .

The above-mentioned " oil-free polymerization " is performed without using a surfactant, and may be also referred to as suspension polymerization.

The above-mentioned monomer mixture is used to produce an acrylic emulsion resin in which a part of the monomer mixture is used to produce the seed and the remaining monomers are then formed on the seed. In order to prepare the seed, the acrylic monomer 1 to 10% by weight, based on the total weight of the mixture, of an acrylic monomer mixture may be used, and specifically 1 to 5% by weight of an acrylic monomer mixture may be used.

When the seed is emulsion-polymerized by using only the acrylic monomer mixture of less than 1% by weight in the above range, the desired effect due to the separate preparation of the seed can not be obtained. As the final particles become too large, And when it is used in an amount exceeding 10% by weight, the stability during production of the seed is deteriorated, so that a large amount of agglomerates are produced, and the size of the final particles is rather small, and the washing property is deteriorated.

The seed in which the acrylic monomer mixture is an emulsion-polymerized seed may have a particle size of 100 to 300 nanometers in detail, and more specifically 150 to 200 nanometers.

When the seed particles are less than 100 nanometers out of the above-described range, there is a problem that the effect of producing the seed is not observed, the final particle is too small or the particle distribution is widened. When the particle size is more than 300 nm There is a problem in stability and a large amount of agglomerates is generated, which is not preferable.

The inventors of the present application have conducted intensive studies and have found that the acrylic emulsion pressure sensitive adhesives prepared so as to satisfy the above conditions can be suitably adjusted so that the size and distribution of the particles can have the desired level of tackiness and washability at the same time .

Specifically, the particle size of the acrylic emulsion pressure-sensitive adhesive thus prepared may be in the range of 300 to 800 nanometers, and more specifically, 400 to 600 nanometers. The particle distribution of the acrylic emulsion pressure- More than 95% of the particles of the acrylic emulsion pressure-sensitive adhesive may have a particle size distribution of an average particle size of +/- 10%, and more particularly, more than 95% of the particles may have a particle size distribution of an average particle size of +/- 5%.

As another factor for the particle distribution, the particles of the acrylic emulsion pressure-sensitive adhesive may have a coefficient of variation of 0.01 to 0.1. Here, the coefficient of variation means a value obtained by dividing the standard deviation by the average particle diameter (D50).

If the particle size of the acrylic emulsion pressure-sensitive adhesive is less than 300 nm or the particle distribution is too wide, the washing property is deteriorated. If the particle size exceeds 800 nm, the stability of the final particle is insufficient, And there is a problem that it is not preferable because there is a problem.

On the other hand, the physical properties of the final material vary depending on the weight percentage of the acrylic monomer mixture and the seed particle size included in the seed, and the type and content of the monomers contained in the acrylic monomer mixture also basically depend on the physical properties of the pressure- As described above, it is also important to control the acrylic-based pressure-sensitive adhesives including the seeds so that the merits of the existing acrylic pressure-sensitive adhesives can be exhibited as effectively as possible. Therefore, the acrylic monomer mixture according to the present invention will be described in detail below.

The acrylic monomer mixture is specifically a mixture of i) a (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms, ii) at least one monomer selected from the group consisting of allyl esters, vinyl esters, unsaturated acetates and unsaturated nitriles, iii) at least one monomer selected from the group consisting of an unsaturated carboxylic acid and a hydroxyl group-containing unsaturated monomer, and iv) a crosslinking agent.

More specifically, the acrylic monomer mixture comprises, based on the total weight of the acrylic monomer mixture, i) 60 to 90% by weight of a (meth) acrylic acid ester monomer having an alkyl group of 1 to 14 carbon atoms, ii) allyl esters, vinyl esters, Unsaturated carboxylic acid and unsaturated nitrile, iii) 0.5 to 5 wt% of at least one monomer selected from the group consisting of unsaturated carboxylic acid and hydroxyl group-containing unsaturated monomer, and iv) 0.1 to 5 wt% 3% by weight.

In one specific example, the monomer of i) is selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (Meth) acrylate, isodecyl acrylate, decyl (meth) acrylate, isopropyl (meth) acrylate, t-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl acrylate, isooctyl acrylate, octyl methacrylate, (Meth) acrylate monomer may be at least one member selected from the group consisting of methacrylate, dodecyl methacrylate, isobornyl methacrylate, and lauryl (meth) acrylate, - 60 to 80% by weight of ethylhexyl acrylate and 20 to 40% by weight of butyl acrylate.

The monomer of i) may be contained in an amount of 60 to 90% by weight based on the total weight of the acrylic monomer mixture. If it is contained in an amount of less than 60% by weight, initial adhesion can not be secured, and if it exceeds 90% by weight The transfer of the pressure-sensitive adhesive to the adherend is largely generated at the time of removal after use, and the washing property is deteriorated.

The number of carbon atoms of the alkyl group in i) may be 1 to 14, more specifically, 2 to 14, and when it is less than 1, the cohesive force of the pressure-sensitive adhesive falls, It is not preferable since it becomes too soft and deteriorates the adhesive property.

In one specific example, the monomer of ii) may be at least one selected from the group consisting of vinyl acetate, vinyl butanoate, vinyl propionate, vinyl laurate, vinyl pyrrolidone, acrylonitrile and methacrylonitrile , Specifically, vinyl acetate, vinyl butyrate, or acrylonitrile.

The monomer of ii) may be contained in an amount of 5 to 35% by weight, more specifically 7 to 25% by weight based on the total weight of the acrylic monomer mixture. When the monomer is contained in an amount of less than 5% by weight, It is not possible to secure sufficient adhesive property. When it exceeds 35% by weight, it is undesirable because it becomes excessively firm and remarkable deterioration of the adhesive strength occurs.

In one specific example, the monomer of iii) is selected from the group consisting of acrylic acid, itaconic acid, maleic anhydride, fumaric acid, crotonic acid methacrylic acid, ethylmethacrylic acid, hydroxymethyl (meth) acrylate, hydroxyethyl , Hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, hydroxyoctyl Glycol (meth) acrylate, and the like.

The monomer of iii) may be contained in an amount of 0.5 to 5% by weight based on the total weight of the acrylic monomer mixture. If it is contained in an amount of less than 0.5% by weight, the pressure-sensitive adhesive becomes too soft, %, It is undesirable because it becomes excessively stiff and remarkable deterioration of the adhesion force occurs.

The cross-linking agent of iv) is added to reinforce the cohesive force. In one specific example, the cross-linking agent in iv) may be a compound having 5 to 15 alkylene oxide groups and having an acrylate group or a vinyl group, There may be mentioned compounds having 6 to 12 oxides and having an acrylate group or a vinyl group, and within the above range, room temperature, aging tackiness and stability are all excellent.

For reference, the number of the alkylene oxide groups means the average number of alkylene oxide groups contained in the cross-linking agent used, and when the number of alkylene oxide groups is less than 5 in the cross-linking agent, the pressure- And when the number of alkylene oxide groups exceeds 15, it becomes undesirable because it becomes more flexible than necessary and the adhesive property is lowered.

In one specific example, the crosslinking agent is an organic crosslinking agent such as polyethylene glycol diacrylate, polypropylene glycol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, ethoxylated trimethylpropane triacrylate, Trimethylolpropyl methacrylate, vinyltrimethoxysilane and divinylbenzene, and the like, and an inorganic crosslinking agent such as aluminum acetyl (meth) acrylate such as tripropylene glycol diacrylate, 1,3-butanediol diacrylate, pentatrytol triacrylate, Acetone, zinc acetate, zirconium carbonate and the like, and more specifically, it may be at least one selected from the group consisting of polyethylene glycol diacrylate and polypropylene glycol diacrylate.

The present invention also discloses a process for producing the above acrylic emulsion pressure-sensitive adhesive.

The method for producing an acrylic emulsion pressure-

(A) at least one monomer selected from the group consisting of i) 60 to 90% by weight of a (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms, ii) at least one monomer selected from the group consisting of allyl esters, vinyl esters, unsaturated acetates and unsaturated nitriles 35 to 35% by weight, iii) 0.5 to 5% by weight of at least one monomer selected from the group consisting of an unsaturated carboxylic acid and a hydroxyl group-containing unsaturated monomer, and iv) 0.1 to 3% by weight of a crosslinking agent to prepare an acrylic monomer mixture.

(B) introducing an acrylic monomer mixture in an amount of 1 to 10% by weight based on the total weight of the acrylic monomer mixture into a reactor and adding an initiator to form an oil-free polymerization;

(C) separately preparing a pre-emulsion solution containing 90 to 99% by weight of an acrylic monomer mixture based on the total weight of the acrylic monomer mixture; And

(D) adding the pre-emulsion solution and the initiator to the reactor in which the seed is prepared, followed by emulsion polymerization to prepare an acrylic emulsion pressure-sensitive adhesive;

.

As used herein, the term " pre-emulsion solution " may further include water, an electrolyte, a surfactant, etc. in addition to the acrylic monomer mixture.

More specifically, the method for producing an acrylic emulsion pressure-sensitive adhesive by emulsion polymerization based on the above-

Specifically, a first step of administering water to a reactor and raising the temperature to 80 DEG C to remove oxygen; (I) from 60 to 90% by weight of a (meth) acrylic acid ester monomer having an alkyl group having from 1 to 14 carbon atoms, ii) from 5 to 35% by weight of at least one monomer selected from the group consisting of allyl esters, vinyl esters, unsaturated acetates and unsaturated nitriles A second step of preparing a monomer mixture comprising 0.5 to 5% by weight of at least one monomer selected from the group consisting of unsaturated carboxylic acids and hydroxyl group-containing unsaturated monomers, and 0.1 to 3% by weight of a crosslinking agent; A third step of administering an acrylic monomer mixture in an amount of 1 to 10% by weight based on the total weight of the monomer mixture to a reactor, stirring the mixture, and then injecting an initiator to produce a seed; Separately, a fourth step of preparing a pre-emulsion solution by adding water, an electrolyte and a surfactant to 90 to 99% by weight of the acrylic monomer mixture based on the total weight of the monomer mixture; A fifth step of continuously introducing the pre-emulsion solution and the initiator of the fourth process into the reactor in which the seed of the third process is prepared, and then heating the mixture at a temperature of 80 ° C and cooling it at room temperature to prepare an acrylic emulsion pressure-sensitive adhesive; And adjusting the pH of the acrylic emulsion pressure-sensitive adhesive to 6 to 9; .

Here, as in the third process, the process of polymerizing without using any surfactant is called an emulsion polymerization. As in the fourth and fifth processes, the process of polymerizing a surfactant in a solution is called emulsion polymerization do.

That is, the seed of the acrylic emulsion pressure-sensitive adhesive according to the present invention is prepared by an emulsion polymerization without using a surfactant, that is, by suspension polymerization, and based on such a seed, an acrylic emulsion pressure-sensitive adhesive can be prepared by emulsion polymerization.

The particle size of the seed thus prepared may be 100 to 300 nanometers as mentioned above.

On the other hand, in one specific example, the initiator may be a water-soluble polymerization initiator such as a persulfate of ammonium or alkali metal, hydrogen peroxide, peroxide, hydroperoxide and the like as a water-soluble initiator. In order to carry out emulsion polymerization reaction at a low temperature It may be used together with one or more reducing agents. The reducing agent may be sodium bisulfite, sodium metabisulfite, sodium hydrosulfite, sodium thiosulfate, sodium formaldehyde sulfoxylate, ascorbic acid, and the like.

In detail, the temperature of the emulsion polymerization reaction may be from 50 to 100 ° C, more specifically from 70 to 90 ° C, and the temperature of the emulsion polymerization reaction may be from 0 to 100 ° C, More specifically, it may be 40 to 90 占 폚. The temperature of the polymerization reaction may be controlled by the use of the initiator alone, or a mixture of one or more of the initiator and the reducing agent.

The electrolyte to be used in the polymerization reaction may be one which is selected from the group consisting of sodium bicarbonate, sodium carbonate, sodium phosphate, sodium sulfate and sodium chloride, and the like. More specifically, may be sodium carbonate, and may be included in an amount of 0.1 to 2 parts by weight, and more specifically 0.3 to 1 part by weight, based on 100 parts by weight of the acrylic monomer mixture used in the emulsion polymerization.

The surfactant is used for controlling the particle size and the stability of particles produced during the emulsion polymerization. The surfactant is composed of a hydrophilic group and a lipophilic group, and is divided into an anion, a cation and a nonionic surfactant. It mainly uses anionic and nonionic surfactants, and is mixed with other surfactants to compensate for mechanical stability and chemical stability.

The anionic surfactant may be sodium alkyldiphenyl oxide disulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium dialkyl sulfosuccinate, and the like. The nonionic surfactant may be, for example, Polyethylene oxide alkylaryl ether, polyethylene oxide alkylamine, polyethylene oxide alkyl ester, etc. These may be used singly or in combination of two or more, and may be more effective when mixed with an anionic surfactant and a nonionic surfactant have.

The acrylic emulsion pressure-sensitive adhesive is an alkaline substance and its pH can be adjusted. The pH of the acrylic emulsion resin may be 6 to 9, more specifically 7 to 8, and the alkaline substance may be a monovalent metal, Inorganic substances such as hydroxides, chlorides and carbonates of divalent metals, ammonia or organic amines, and the like.

Furthermore, the acrylic emulsion pressure sensitive adhesive according to the present invention may further include a thickening agent and a wetting agent in order to prevent shrinkage of the acrylic emulsion pressure-sensitive adhesive which is generated when coating the surface of the silicone release paper.

The thickening agent may be CMC (Carboxyl Methyl Cellulose), acrylic sol, polyvinyl alcohol, starch, alginate, dextrin and the like, and more specifically polyvinyl alcohol.

The wetting agent may be a surfactant mixture, and may further include a glycol or an alcohol. The hydrophilic adhesive may be hydrophobic to closely adhere the adhesive to the surface of the hydrophobic silicone release paper.

The present invention also provides a pressure-sensitive adhesive sheet in which an acrylic emulsion pressure-sensitive adhesive is applied on an ink film or sheet to form a pressure-sensitive adhesive layer.

The pressure-sensitive adhesive sheet may be a point-worn film or sheet used for a label for a printing, a chemical, a medicine, an appliance, an automobile, a stationary, In detail, it may be 20 to 30 占 퐉, is excellent in coating property and has sufficient adhesive property.

INDUSTRIAL APPLICABILITY As described above, according to the present invention, the acrylic emulsion pressure-sensitive adhesive is prepared by mixing and emulsion-polymerizing the remaining acrylic monomer mixture with a seed in which a certain amount of the acrylic monomer mixture is an emulsion- It is possible to produce uniformly with an appropriate size, to exhibit excellent adhesive property, and at the same time to increase the water absorption rate in washing and to be easily removed.

Hereinafter, the present invention will be described with reference to Examples. However, the following Examples are intended to illustrate the present invention, and the scope of the present invention is not limited thereto.

≪ Example 1 >

300 g of water was added to a 3 L glass reactor equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser, and the inside of the reactor was replaced with nitrogen while stirring. Then, the temperature was raised to 80 ° C under a nitrogen atmosphere, Respectively.

Separately, 250 g of butyl acrylate, 538 g of 2-ethylhexyl acrylate, 100 g of methyl methacrylate, 100 g of vinyl acetate, 10 g of acrylic acid, 1 g of polyethylene glycol 400 diacrylate and 1 g of normal dodecyl mercaptan 1 g were added and mixed for 30 minutes to prepare 1000 g of a monomer mixture.

50 g of the monomer mixture was charged into the reactor, stirred for 10 minutes, and 10 wt% and 10 g of ammonium antioxidant were added to the reactor to perform the reaction for preparing the seed. After completion of the reaction, the mixture was stirred at the same temperature for 1 hour.

Separately, 950 g of 26 wt% sodium polyoxyethylene lauryl ether sulfate, 10.4 g of 45 wt% alkyldiphenyl oxide disulfonate, 2 g of sodium carbonate, 2 g of sodium methyl allyl sulfonate, and 2 g of water 220 g was added and mixed with a stirrer to prepare a whitecap preemulsion.

The pre-emulsion and 150 g of a 10 wt% aqueous ammonium sulfate solution were continuously and continuously added to the glass reactor in which the seed was prepared for 4 hours, and then 10 g of a 10 wt% aqueous solution of ammonium sulfate was further added thereto. , Maintained at this temperature for 1 hour, and then cooled to room temperature to prepare an acrylic emulsion pressure-sensitive adhesive.

A 10 wt% sodium hydroxide aqueous solution was added to the acrylic emulsion pressure-sensitive adhesive to adjust the pH to 7 to 8.

≪ Example 2 >

The procedure of Example 1 was repeated except that 10 g of 1000 g of the entire monomer mixture was used for the preparation of the seed of Example 1 above.

≪ Example 3 >

The procedure of Example 1 was repeated except that 30 g of 1000 g of the entire monomer mixture was used for the preparation of the seed of Example 1 above.

<Example 4>

The procedure of Example 1 was repeated except that 70 g of 1000 g of the entire monomer mixture was used for the preparation of the seed of Example 1 above.

&Lt; Example 5 >

The procedure of Example 1 was repeated except that 100 g of 1000 g of the entire monomer mixture was used for the preparation of the seed of Example 1 above.

&Lt; Example 6 >

Separately, in Example 1, 250 g of butyl acrylate, 488 g of 2-ethylhexyl acrylate, 150 g of methyl methacrylate, 100 g of vinyl acetate, 10 g of acrylic acid, 1 g of polyethylene glycol 400 diacrylate and 1 g of normal dodecyl mercaptan Was added and mixed for 30 minutes to prepare 1000 g of a monomer mixture.

&Lt; Example 7 >

Separately from Example 1, 250 g of butyl acrylate, 488 g of 2-ethylhexyl acrylate, 100 g of methyl methacrylate, 150 g of vinyl acetate, 10 g of acrylic acid, 1 g of polyethylene glycol 400 diacrylate and 1 g of normal dodecyl mercaptan were added to the beaker The mixture was stirred for 30 minutes after the addition, and 1000 g of a monomer mixture was prepared, and the same procedure as in Example 1 was carried out

&Lt; Comparative Example 1 &

In Example 1, 300 g of water and 3.8 g of 26 wt% sodium polyoxyethylene lauryl ether sulfate were initially charged into a 3 L glass reactor, and then, in the preparation of the white emulsion pre-emulsion separately, 26 wt% sodium poly The procedure of Example 1 was repeated except that 15.4 g of oxyethylene lauryl ether sulfate was added.

&Lt; Comparative Example 2 &

In Example 1, the same procedure as in Example 1 was carried out except that 9 g of 1000 g of the entire monomer mixture was used for producing the seed.

&Lt; Comparative Example 3 &

In Example 1, the same procedure as in Example 1 was carried out except that 105 g of 1000 g of the entire monomer mixture was used for producing the seed.

&Lt; Comparative Example 4 &

In Example 1, 300 g of water and 3.8 g of 26 wt% sodium polyoxyethylene lauryl ether sulfate were initially charged in a 3 L glass reactor, 10 g of 1000 g of the entire monomer mixture was used for the preparation of the seed, The procedure of Example 1 was repeated except that 15.4 g of 26% by weight sodium polyoxyethylene lauryl ether sulfate was added to the monomer mixture in the preparation of the opaque white emulsion.

&Lt; Comparative Example 5 &

In Example 1, 300 g of water and 0.38 g of 26 wt% sodium polyoxyethylene lauryl ether sulfate were initially charged in a 3 L glass reactor, 10 g of 1000 g of the entire monomer mixture was used for the preparation of the seed, The procedure of Example 1 was repeated except that 18.82 g of 26% by weight sodium polyoxyethylene lauryl ether sulfate was added to the monomer mixture in the preparation of the opaque white emulsion.

&Lt; Comparative Example 6 >

In Example 1, 300 g of water and 3.8 g of 26 wt% sodium polyoxyethylene lauryl ether sulfate were initially charged in a 3 L glass reactor, 100 g of 1000 g of the entire monomer mixture was used for the preparation of the seed, The procedure of Example 1 was repeated except that 15.4 g of 26% by weight sodium polyoxyethylene lauryl ether sulfate was added to the monomer mixture in the preparation of the opaque white emulsion.

&Lt; Comparative Example 7 &

In Example 1, 300 g of water and 3.8 g of 26 wt% sodium polyoxyethylene lauryl ether sulfate were initially charged in a 3 L glass reactor, 5 g of 1000 g of the entire monomer mixture was used for the preparation of the seed, The procedure of Example 1 was repeated except that 15.4 g of 26% by weight sodium polyoxyethylene lauryl ether sulfate was added to the monomer mixture in the preparation of the opaque white emulsion.

&Lt; Comparative Example 8 >

300 g of water was added to a 3 L glass reactor equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen inlet tube and a reflux condenser, and the inside of the reactor was replaced with nitrogen while stirring. Then, the temperature was raised to 80 ° C under a nitrogen atmosphere, Respectively.

Separately, 250 g of butyl acrylate, 538 g of 2-ethylhexyl acrylate, 100 g of methyl methacrylate, 100 g of vinyl acetate, 10 g of acrylic acid, 1 g of polyethylene glycol 400 diacrylate and 1 g of normal dodecyl mercaptan To 1000 g of the monomer mixture which had been added for 30 minutes after the addition of 1 g, 19.2 g of 26% by weight sodium polyoxyethylene lauryl ether sulfate, 10.4 g of 45% by weight alkyldiphenyl oxide disulfonate, 2 g of sodium carbonate, 2 g of sulfonate and 220 g of water was added and mixed with a stirrer to prepare a white emulsion pre-emulsion.

The pre-emulsion and 150 g of an aqueous ammonium sulfate solution (150 g) were continuously added to the glass reactor continuously for 4 hours, and then 10 g of a 10 wt% aqueous solution of ammonium persulfate was further added thereto. This temperature was maintained for a period of time and then cooled to room temperature to prepare an acrylic emulsion pressure-sensitive adhesive.

A 10 wt% sodium hydroxide aqueous solution was added to the acrylic emulsion pressure-sensitive adhesive to adjust the pH to 7 to 8.

<Experimental Example 1>

The average particle size and particle distribution of the pressure-sensitive adhesives prepared in Examples 1 to 7 and Comparative Examples 1 to 8 were measured and the results are shown in Table 1 below.

division Seed content
(weight%) Initial surfactant
(Parts by weight) Average particle size
(nm) Particle distribution
(%) Example One 5 - 530 8.7 2 One - 770 9.5 3 3 - 680 9.0 4 7 - 410 8.2 5 10 - 310 8.0 6 5 - 510 8.5 7 5 - 500 8.3 Comparative Example One 5 0.1 250 22.1 2 0.9 - 830 9.7 3 10.5 - 250 7.8 4 One 0.1 370 18.9 5 One 0.01 590 14.8 6 10 0.1 180 17.0 7 0.5 0.1 430 15.9 8 - - 320 35.2

* Seed content: Mixed monomer weight to be included in the seed preparation relative to the total weight of the mixed monomer%

Initial Surfactant: The amount of surfactant contained in the initial reactor relative to 100 parts by weight of the mixed monomer

* Particle distribution: When particles of 95% or more of the acrylic emulsion pressure-sensitive adhesive have a distribution within ± x% of the average particle size, the x value

<Experimental Example 2>

Manufacture of paper labels coated with adhesive

The acrylic emulsion pressure-sensitive adhesives prepared in Examples 1 to 7 and Comparative Examples 1 to 8 were coated on a silicone-coated release paper and dried in an oven at 120 ° C for 1 minute to have an adhesive layer having a thickness of 20 μm. The film was laminated with a polyethylene terephthalate film to produce a film label, and cut to a size of 1 inch x 100 mm to prepare a film label specimen.

The adhesive properties of the acrylic emulsion pressure-sensitive adhesives prepared in Examples 1 to 7 and Comparative Examples 1 to 8 were tested by the following methods, and the results are shown in Table 2 below.

* Measurement of aggregate content : 100 g of the prepared emulsion acrylic pressure-sensitive adhesive is washed with distilled water, which is filtered on a mesh having a scale size of 74 μm according to the process standard, and then the water is made transparent and dried at a temperature of 110 ° C. or lower. The amount of dried residue is compared with the weight before drying and substituted into the above formula at the weight before and after drying to convert the content into a percentage.

* Initial Adhesion Test : Test Method FINAT TEST METHOD NO. 9, an acrylic emulsion pressure-sensitive adhesive film label specimen was made into a ring shape, and the glass surface was attached to the glass surface without applying pressure. After 5 seconds, it was measured 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 acrylic emulsion pressure-sensitive adhesive film label specimen was reciprocated twice on a glass plate at a speed of 2 kg roller at a rate 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 Acrylic Emulsion Adhesive Film Label The specimen was attached to the stainless steel surface (SUS 304) so that the adhered surface was 1 x 1 inch. After holding for 30 minutes in the oven at 70 ° C while holding it with the weight of 500 g, remove the weight, Cool for minutes. Thereafter, a weight of 1 kg is put on the end of the seat, and the time for further dropping is measured.

* Cleaning force test : Acrylic emulsion pressure-sensitive adhesive film label specimen is attached on a glass plate and pressed twice with a 2kg roller at a speed of 300mm / min twice. After 1 hour, the entire specimen was soaked in a water bath for 1 day, then taken out of the water bath to gently wipe the surface water, and the physical properties thereof were measured according to the peel strength test method. (Unit: N / in) It is judged that the lower the peeling force, the better the washing ability.

division Aggregate content
(ppm) Initial adhesion
(N / in) 90 degree peel force
(N / in) cohesion
(time) Peel strength (washability)
(N / in) Example 1 500 15.5 8.3 50 1.2 Example 2 650 14.5 7.5 37 0.9 Example 3 550 15.0 7.8 41 1.1 Example 4 500 15.5 8.5 57 1.5 Example 5 590 15.9 8.7 59 1.7 Example 6 480 14.7 7.9 70 1.4 Example 7 510 17.0 9.2 27 1.2 Comparative Example 1 470 15.9 8.5 57 5.3 Comparative Example 2 1200 14.0 7.1 25 0.9 Comparative Example 3 780 16.3 8.3 60 2.5 Comparative Example 4 510 15.5 8.0 57 2.9 Comparative Example 5 500 15.3 8.2 51 2.3 Comparative Example 6 570 16.5 8.5 67 5.9 Comparative Example 7 550 15.0 8.1 52 3.0 Comparative Example 8 820 14.1 7.3 35 4.8

Referring to Tables 1 and 2, the particles of the acrylic emulsion pressure-sensitive adhesive of Examples 1 to 7 were neither too large nor too small, and the particle distribution was as small as 10% or less and uniform, The aggregates are less likely to occur, the overall physical properties are good, and the washing property is excellent. On the other hand, the acrylic emulsion pressure-sensitive adhesives of Comparative Examples 1 to 8 show that the particle size is too large or small, or the particle distribution is too wide, .

Specifically, the acrylic emulsion pressure-sensitive adhesives of Comparative Examples 1 and 6 had a small size of final particles and a wide distribution of particles as a surfactant was used in the production of the seed, When the content of the monomer mixture used in the seed production is out of the range of the claimed content, when the content is out of the range, the size of the final particles is too large, resulting in a large amount of aggregates due to insufficient stability. It was confirmed that the stability was poor and a large amount of agglomerates were formed, and the size of the final particles was small and the washing ability was deteriorated.

In addition, the acrylic emulsion pressure-sensitive adhesives of Comparative Examples 4, 5, and 7 used a surfactant in the preparation of the seed, but the final particle size was adequate, It was confirmed that the detergency was completely deteriorated because the particle distribution was very wide as the acrylic emulsion pressure-sensitive adhesive was prepared.

Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (19)

Based monomer mixture is an emulsion-polymerized emulsion polymer obtained by emulsion-polymerizing an acrylic monomer mixture in an amount of 90 to 99% by weight based on the total weight of the acrylic monomer mixture, The seed is wrapped by an acrylic emulsion resin,
The particle size of the acrylic emulsion pressure-sensitive adhesive is from 300 nanometers to 800 nanometers,
Wherein the acrylic monomer mixture comprises i) at least one monomer selected from the group consisting of (meth) acrylic acid ester monomers having an alkyl group of 1 to 14 carbon atoms, ii) allyl esters, vinyl esters, unsaturated acetates and unsaturated nitriles, iii) At least one monomer selected from the group consisting of acid and hydroxyl group-containing unsaturated monomers, and iv) a crosslinking agent. The acrylic emulsion pressure-sensitive adhesive according to claim 1, wherein the seed is an oil-free polymerization of 1 to 5% by weight of an acrylic monomer mixture based on the total weight of the acrylic monomer mixture. delete The composition according to claim 1, wherein the acrylic monomer mixture comprises, based on the total weight of the acrylic monomer mixture, i) 60 to 90% by weight of a (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms, ii) an allyl ester, From 5 to 35% by weight of at least one monomer selected from the group consisting of acrylic acid and unsaturated nitrile, iii) from 0.5 to 5% by weight of at least one monomer selected from the group consisting of unsaturated carboxylic acids and hydroxyl group-containing unsaturated monomers, and iv) 0.1 to 3% by weight of the acrylic emulsion. The method of claim 1, wherein the monomer of i) is selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) (Meth) acrylate, isodecyl acrylate, decyl (meth) acrylate, isopropyl (meth) acrylate, t-butyl methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl acrylate, isooctyl acrylate, octyl methacrylate, Wherein the acrylic emulsion pressure-sensitive adhesive is at least one selected from the group consisting of methacrylate, dodecyl methacrylate, isobornyl methacrylate, and lauryl (meth) acrylate. [7] The composition according to claim 5, wherein the monomer of i) is a mixture of 60 to 80% by weight of 2-ethylhexyl acrylate and 20 to 40% by weight of butyl acrylate based on the total weight of the (meth) acrylic acid ester monomer Acrylic emulsion adhesive. The method according to claim 1, wherein the monomer of ii) is at least one selected from the group consisting of vinyl acetate, vinyl butanoate, vinyl propionate, vinyl laurate, vinyl pyrrolidone, acrylonitrile and methacrylonitrile Acrylic emulsion pressure-sensitive adhesive. The composition of claim 1, wherein the monomer of iii) is selected from the group consisting of acrylic acid, itaconic acid, maleic anhydride, fumaric acid, crotonic acid methacrylic acid, ethylmethacrylic acid, hydroxymethyl (meth) acrylate, hydroxyethyl , Hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, hydroxyoctyl Glycol (meth) acrylate, and acrylic (meth) acrylate. The acrylic emulsion pressure-sensitive adhesive according to claim 1, wherein the crosslinking agent in iv) contains 5 to 15 alkylene oxide groups and is a compound having an acrylate group or a vinyl group. The acrylic emulsion pressure-sensitive adhesive according to claim 9, wherein the crosslinking agent is at least one selected from the group consisting of polyethylene glycol diacrylate and polypropylene glycol diacrylate. The acrylic emulsion pressure-sensitive adhesive according to claim 1, wherein the particle size of the seed is 100 to 300 nanometers. delete The acrylic emulsion pressure-sensitive adhesive according to claim 1, wherein at least 95% of the acrylic emulsion pressure-sensitive adhesive has a particle size distribution of an average particle size of +/- 10%. The acrylic emulsion pressure-sensitive adhesive according to claim 1, wherein the particles of the acrylic emulsion pressure-sensitive adhesive have a coefficient of variation of 0.01 to 0.1. A method for producing an acrylic emulsion pressure-sensitive adhesive according to claim 1,
(A) at least one monomer selected from the group consisting of i) 60 to 90% by weight of a (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms, ii) at least one monomer selected from the group consisting of allyl esters, vinyl esters, unsaturated acetates and unsaturated nitriles 35 to 35% by weight, iii) 0.5 to 5% by weight of at least one monomer selected from the group consisting of an unsaturated carboxylic acid and a hydroxyl group-containing unsaturated monomer, and iv) 0.1 to 3% by weight of a crosslinking agent to prepare an acrylic monomer mixture.
(B) introducing an acrylic monomer mixture in an amount of 1 to 10% by weight based on the total weight of the acrylic monomer mixture into a reactor and adding an initiator to form an oil-free polymerization;
(C) separately preparing a pre-emulsion solution containing 90 to 99% by weight of an acrylic monomer mixture based on the total weight of the acrylic monomer mixture; And
(D) adding the pre-emulsion solution and the initiator to the reactor in which the seed is prepared, followed by emulsion polymerization to prepare an acrylic emulsion pressure-sensitive adhesive;
/ RTI &gt;
Wherein the acrylic emulsion pressure-sensitive adhesive has a particle size of 300 nanometers to 800 nanometers. 16. The method of claim 15, wherein the initiator is at least one selected from the group consisting of persulfates of ammonium or alkali metals, hydrogen peroxide, peroxide, and hydroxoxide. 16. The method of claim 15, wherein the particle size of the seed is 100 to 300 nanometers. 16. The method of claim 15, wherein the pre-emulsion solution further comprises water, an electrolyte, and a surfactant. A pressure-sensitive adhesive layer is formed by applying the acrylic emulsion pressure-sensitive adhesive according to any one of claims 1, 2, 4, 11, 13, and 14 onto a spotting film or sheet Adhesive sheet.