JP6397058B2 - Acrylic emulsion adhesive excellent in detergency and method for producing the same - Google Patents

Description

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

  A pressure-sensitive adhesive (PSA) is a semi-solid substance having a property of adhering to an adherent with a small pressure, and is a viscoelastic substance different from an adhesive. It has the basic properties of strength and cohesion and is used in most industrial fields such as printing, chemistry, pharmaceuticals, home appliances, automobiles, stationery, as well as product trademarks and advertisements.

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

  In the past, most of the adhesives used in adhesive tapes and adhesive labels were rubber adhesives or solvent-based adhesives, but as demand for environmentally friendly adhesives increased, solventless adhesives Interest and technology development related to adhesives has progressed, and now the development and production of solvent-free adhesives have increased greatly, and the trend is to continue increasing. Such a solventless pressure-sensitive adhesive is typically polymerized by an aqueous emulsion polymerization method.

  Since water-based emulsion pressure-sensitive adhesive is independent of the viscosity of the pressure-sensitive adhesive and the molecular weight of the dispersion polymer, a polymer having a higher molecular weight than that of a solvent-based polymer can be used, and a solid content concentration range can be obtained over a wide range. It has the advantages of low aging resistance, low viscosity, good adhesion in the low solid content region, and good compatibility with other polymers.

  However, since water is used as a solvent, the drying speed is slow, the adhesiveness to the hydrophobic adhesive surface and the nonporous adherent is low, the selection range of the curing agent is narrow, and the initial adhesiveness is reduced. In addition to having an emulsifier and a dispersant, it has problems such as low water resistance and physical properties that are not as good as those of an oil-based adhesive.

  On the other hand, polymerization methods for producing an acrylic emulsion adhesive resin can be classified into a solution type and an emulsion polymerization type.

  Among them, the solution type has the advantage that the reaction conditions of the polymerization can be easily adjusted and a uniform polymer can be efficiently produced. However, since a solvent is used, the molecular weight of the polymer is different from that of other polymerization methods. Compared to this, the polymerization rate is low and the chain transfer by the solvent is inevitable. Therefore, there are many limitations such as the use of a solvent that induces as little chain transfer as possible.

  On the other hand, the emulsion polymerization type is economical because it has a high affinity for water, does not require a post-treatment step, completes the reaction within a few hours, and the conversion rate is almost 100%. Is mainly produced through an emulsion polymerization type instead of a solution type.

  However, the water-based emulsion pressure-sensitive adhesive synthesized by the emulsion polymerization type has a problem in that the stability is insufficient when the size of the particles is very large or small, so that many aggregates are generated and the physical properties are lowered. There is.

  Recently, there is an increasing demand for reusing insufficient resources and environmentally conscious products. An adhesive film or sheet using such an aqueous emulsion adhesive or acrylic emulsion adhesive is used. In order to reuse the adherent after making and using it, an additional step of removing the film or sheet from the adherent is necessarily required, but currently the removal only takes a considerable amount of time. However, there is a problem that it is impossible to reuse the adherend itself from the beginning. Therefore, in order to completely remove the film or sheet from the adherend and reduce the time required for this, there is a high demand for an effect as excellent as tackiness.

  However, the general water-based emulsion adhesive synthesized by the emulsion polymerization type is difficult to clean because the particle size is small or the particle distribution is very wide. Cause problems such as lowering.

  Therefore, there is a high need for the technology of an acrylic emulsion pressure-sensitive adhesive that exhibits excellent adhesive properties and excellent cleaning properties.

  An object of the present invention is to solve the above-described problems of the prior art and technical problems that have been requested from the past.

  As a result of earnest research and various experiments, the inventors of the present application first produced a seed in which an acrylic monomer mixture was non-emulsified and polymerized, and the acrylic monomer mixture was produced together with the seed. When producing an acrylic emulsion pressure-sensitive adhesive by mixing and emulsion polymerization, the final particles of the acrylic emulsion pressure-sensitive adhesive have an appropriate size and are uniform, so that they have excellent pressure-sensitive adhesive properties and can be washed with water. It was confirmed that it was easy and the present invention was completed.

  Accordingly, the acrylic emulsion pressure-sensitive adhesive according to the present invention is a seed obtained by non-emulsifying polymerization of 1 to 10% by weight of the acrylic monomer mixture, based on the total weight of the acrylic monomer mixture, and 90 to 99% by weight of an acrylic monomer mixture contains an emulsion polymer obtained by emulsion polymerization, and the seed is wrapped with the acrylic emulsion resin.

  The term “monomer mixture” used in the present specification may be manufactured based on an acrylic monomer and charged with the monomers described below mixed together. It includes diversity such that the monomers may be sequentially added and manufactured.

  The “non-emulsification polymerization” is a polymerization in a water phase with a hydrophilic initiator without using a surfactant, and can also be called a suspension polymerization.

  The monomer mixture is used in part to produce the seed, and the remaining monomers are subsequently used to produce the acrylic emulsion resin formed on the seed. At this time, in order to manufacture the seed, as mentioned above, an acrylic monomer mixture of 1 to 10% by weight based on the total weight of the acrylic monomer mixture may be used. Specifically, 1 to 5% by weight of an acrylic monomer mixture may be used.

  When the seed is non-emulsified using only an acrylic monomer mixture of less than 1% by weight outside the above range, the desired effect by separately producing the seed cannot be obtained. Since it becomes excessively large and the stability is insufficient, there is a problem that a large amount of agglomerates are generated, and when it is used in excess of 10% by weight, the stability is deteriorated during the production of seeds, At the same time as the occurrence of many, there is a problem that the size of the final particles becomes rather small, so that the detergency deteriorates.

  As described above, the seed obtained by non-emulsification polymerization of the acrylic monomer mixture may have a particle size of 100 to 300 nm in detail, or 150 to 200 nm in more detail.

  If the particle outside the range is less than 100 nm, the effect of producing the seed cannot be obtained, so that there is a problem that the final particle is excessively small or the particle distribution is wide, When the thickness exceeds 300 nm, there is a problem in stability, and there is a problem in that a large amount of aggregates are generated.

  As a result of extensive research, the inventors of the present application have found that acrylic emulsion pressure-sensitive adhesives manufactured so as to satisfy the above-described conditions have a particle size and distribution of a desired level of tackiness and It was confirmed that it can be adjusted as appropriate so that it can have detergency at the same time.

  Specifically, the particle size of the acrylic emulsion pressure-sensitive adhesive thus produced may be 300 to 800 nm in detail, and may be 400 to 600 nm in more detail. The particle distribution of the acrylic emulsion pressure-sensitive adhesive may be such that 95% or more of the particles of the acrylic emulsion pressure-sensitive adhesive have a particle distribution of ± 10% of the average particle size, and more specifically, 95% or more of the particles. Can have a particle distribution of ± 5% of the average particle size.

  Further, as another factor for the particle distribution, the acrylic emulsion pressure-sensitive adhesive particles 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 size (D50).

  When the particle size of the acrylic emulsion pressure-sensitive adhesive is out of the above range and the particle size is less than 300 nm or the particle distribution is excessively wide, the detergency is deteriorated, and when the particle size exceeds 800 nm, the final particle This is not preferable because there is a problem that the stability of the material is insufficient and a large amount of aggregates are generated.

  On the other hand, the amount of the acrylic monomer mixture contained in the seed and the physical properties of the final material change according to the seed particle size, as well as the single amount contained in the acrylic monomer mixture. The type and content of the body basically influences the physical properties of the adhesive. As described above, the advantages of the existing acrylic adhesive are most effectively applied to the acrylic emulsion adhesive containing seeds. It is important to adjust this so that it can be exerted. Therefore, the acrylic monomer mixture according to the present invention will be described in detail below.

  Specifically, the acrylic monomer mixture includes i) (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms, ii) allyl ester, vinyl ester, unsaturated acetate, and unsaturated nitrile. One or more monomers selected from the group consisting of: iii) one or more monomers selected from the group consisting of unsaturated carboxylic acids and hydroxyl group-containing unsaturated monomers, and iv) a crosslinking agent. Can be included.

  More specifically, the acrylic monomer mixture is based on the total weight of the acrylic monomer mixture, i) (meth) acrylic acid ester monomer 60 to 60 having an alkyl group having 1 to 14 carbon atoms. 90% by weight, ii) 5-35% by weight of one or more monomers selected from the group consisting of allyl ester, vinyl ester, unsaturated acetate and unsaturated nitrile, iii) unsaturated carboxylic acid and hydroxyl group-containing unsaturated 0.5 to 5% by weight of one or more monomers selected from the group consisting of monomers, and iv) 0.1 to 3% by weight of a crosslinking agent can be included.

  In one specific example, the monomer of i) is methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl acrylate, t-butyl. The group consisting of methacrylate, pentyl methacrylate, hexyl methacrylate, heptyl acrylate, isooctyl acrylate, octyl methacrylate, 2-ethylhexyl (meth) acrylate, isodecyl acrylate, decyl methacrylate, dodecyl methacrylate, isobornyl methacrylate, and lauryl (meth) acrylate One or more selected from the group consisting of 2-ethylhexyl acrylate, in particular based on the total weight of the (meth) acrylate monomer. 60-80 may be a weight percent and butyl acrylate mixture of 20 to 40 wt%.

  The monomer of i) may be included in an amount of 60 to 90% by weight based on the total weight of the acrylic monomer mixture. However, if the content exceeds 90% by weight, transfer of the pressure-sensitive adhesive to the adherend is greatly generated at the time of removal after use, which is not preferable.

  In addition, the number of carbon atoms of the alkyl group in i) may be 1 to 14 in detail, more specifically 2 to 14 or less than 1. When the cohesive force of the pressure-sensitive adhesive is reduced and it exceeds 14, it is not preferable because it becomes too flexible and the physical properties of the pressure-sensitive adhesive deteriorate.

  In one embodiment, the monomer of ii) is one or more selected from the group consisting of vinyl acetate, vinyl butanoate, vinyl propionate, vinyl laurate, vinyl pyrrolidone, acrylonitrile and methacrylonitrile. In particular, it may be vinyl acetate, vinyl butanoate or acrylonitrile.

  The monomer of ii) may be included in an amount of 5 to 35% by weight based on the total weight of the acrylic monomer mixture, and may be included in detail in an amount of 7 to 25% by weight and less than 5% by weight. If it is included, the pressure-sensitive adhesive becomes too soft to ensure sufficient adhesive properties, and if it exceeds 35% by weight, it becomes too hard and a significant decrease in adhesive strength occurs. Therefore, it is not preferable.

  In one embodiment, the monomer of iii) is acrylic acid, itaconic acid, maleic anhydride, fumaric acid, crotonic acid, methacrylic acid, ethyl methacrylate, hydroxymethyl (meth) acrylate, hydroxyethyl (meth) acrylate. , Hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, hydroxyoctyl (meth) acrylate, hydroxylauryl (meth) acrylate and hydroxypropylene glycol (meth) acrylate There may be one or more.

  The monomer of iii) may be included in an amount of 0.5 to 5% by weight based on the total weight of the acrylic monomer mixture. When the content of the adhesive exceeds 5% by weight, it becomes too hard and a significant decrease in adhesive strength occurs, which is not preferable.

  The crosslinking agent iv) is added to reinforce the cohesive force. In one specific example, the crosslinking agent may be a compound containing 5 to 15 alkylene oxide groups and having an acrylate group or a vinyl group. Well, specifically, it may be a compound containing 6 to 12 alkylene oxide groups and having an acrylate group or a vinyl group, and within the above-mentioned range, it has the effect of being excellent in normal temperature, aging adhesiveness and stability. is there.

  For reference, the number of alkylene oxide groups means the average number of alkylene oxide groups contained in the used crosslinking agent, and the pressure-sensitive adhesive produced when the number of alkylene oxide groups is less than 5 in the crosslinking agent. If the agent becomes harder than necessary and the initial adhesive strength is reduced, and the number of alkylene oxide groups exceeds 15, it is unpreferable because it becomes more flexible than necessary and the adhesive properties deteriorate.

  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, tripropylene glycol. Diacrylate, 1,3-butanediol diacrylate, pentaerythritol triacrylate, 3-trimethoxysilylpropyl methacrylate, vinyltrimethoxysilane, divinylbenzene, etc. and aluminum acetylacetonate, zinc acetate, zirconium carbonate as inorganic crosslinking agents One or more selected from the group consisting of, for example, polyethylene glycol diacrylate and polypropylene glycol It may be one or more selected from the group consisting of diacrylates.

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

  The method for producing the acrylic emulsion adhesive is:

  (A) i) 60-90 wt% of (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms, ii) selected from the group consisting of allyl ester, vinyl ester, unsaturated acetate and unsaturated nitrile 5 to 35% by weight of one or more monomers selected, iii) 0.5 to 5% by weight of one or more monomers selected from the group consisting of unsaturated carboxylic acids and hydroxyl group-containing unsaturated monomers And iv) mixing 0.1 to 3% by weight of a crosslinking agent to produce an acrylic monomer mixture;

  (B) 1-10 wt% acrylic monomer mixture is added to the reactor based on the total weight of the acrylic monomer mixture, and an initiator is added to produce a seed by non-emulsification polymerization. Process to do;

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

  (D) A process of preparing an acrylic emulsion adhesive by emulsion polymerization after adding the pre-emulsion solution and the initiator to the reactor in which the seed is manufactured;

  including.

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

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

  Specifically, the first step of adding water to the reactor and raising the temperature to 80 ° C. to remove oxygen; separately, i) (meth) acrylic acid having an alkyl group having 1 to 14 carbon atoms 60-90% by weight of ester monomer, ii) 5-35% by weight of one or more monomers selected from the group consisting of allyl ester, vinyl ester, unsaturated acetate and unsaturated nitrile, iii) unsaturated carboxylic acid Produces a monomer mixture containing 0.5 to 5% by weight of one or more monomers selected from the group consisting of acid and hydroxyl group-containing unsaturated monomers, and 0.1 to 3% by weight of a crosslinking agent A second step in which 1 to 10% by weight of an acrylic monomer mixture based on the total weight of the monomer mixture is charged into the reactor, stirred, and then an initiator is charged to produce seeds. 3 steps; apart from this, the total weight of the monomer mixture Fourth step of preparing pre-emulsion solution by adding water, electrolyte and surfactant to 90-99% by weight acrylic monomer mixture as a reference; in the reactor in which the seed of the third step was manufactured 4 steps of pre-emulsion solution and initiator are continuously added, the temperature is raised to 80 ° C. and then cooled to room temperature to produce an acrylic emulsion pressure-sensitive adhesive; and the pH of the acrylic emulsion pressure-sensitive adhesive is 6 to The sixth step of adjusting to 9 may be configured.

  Here, the process of polymerizing without using a separate surfactant as in the third process is called non-emulsion polymerization, and the surfactant is included in the solution as in the fourth and fifth processes. The process of polymerization is called emulsion polymerization.

  That is, the seed of the acrylic emulsion pressure-sensitive adhesive according to the present invention is manufactured by non-emulsification polymerization without using a surfactant, that is, suspension polymerization. Based on such seed, the acrylic emulsion pressure-sensitive adhesive is emulsified. It can be produced by polymerization.

  The particle size of the seed thus manufactured may be 100 to 300 nm as described above.

  On the other hand, in one specific example, the initiator may be a water-soluble initiator, and may be a water-soluble polymerization initiator such as ammonium or alkali metal persulfate, hydrogen peroxide, peroxide, hydroperoxide, In order to perform the emulsion polymerization reaction at a low temperature, it can 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.

  The temperature of the non-emulsion polymerization reaction may specifically be 50 to 100 ° C., more specifically 70 to 90 ° C., and the temperature of the emulsion polymerization reaction may be 0 to 100 in detail. ° C may be sufficient, and 40-90 ° C may be sufficient in more detail. The temperature of the polymerization reaction can be adjusted by using the initiator alone or by using a mixture of one or more of the initiator and the reducing agent.

  The electrolyte used in the polymerization reaction adjusts the pH and gives stability to the acrylic emulsion adhesive to be polymerized. Specifically, sodium bicarbonate, sodium carbonate, sodium phosphate, sodium sulfate And may be one or more selected from the group consisting of sodium chloride and the like, specifically sodium carbonate, based on 100 parts by weight of the acrylic monomer mixture used for the emulsion polymerization. 0.1 to 2 parts by weight may be included, and in detail, 0.3 to 1 part by weight may be included.

  The surfactant is used to adjust the size of the particles produced during the emulsion polymerization and to stabilize the particles, and is composed of a hydrophilic group and a lipophilic group, and has an anionic, cationic and nonionic surface activity. It is divided into agents. Anionic and nonionic surfactants are mainly used, and they may be used in combination with each other to supplement mechanical stability and chemical stability.

  The anionic surfactant may be sodium alkyl diphenyl oxide disulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene lauryl ether sulfate, sodium dialkyl sulfosuccinate and the like, and the nonionic surfactant is Polyethylene oxide alkyl aryl ether, polyethylene oxide alkyl amine, polyethylene oxide alkyl ester, etc. may be used, and these can be used alone or in combination of two or more. Anionic surfactants and nonionic surfactants can be used. It is more effective than the case of using it by mixing.

  The acrylic emulsion pressure-sensitive adhesive can adjust the acidity (pH) with an alkaline substance, and the pH of the acrylic emulsion resin may be 6-9 in detail, more specifically 7-8. The alkaline substance may be a monovalent metal or a divalent metal hydroxide, an inorganic substance such as a chloride or a carbonate, ammonia or an organic amine.

  Furthermore, the acrylic emulsion pressure-sensitive adhesive according to the present invention includes a thickener and a wetting agent in order to prevent the shrinkage phenomenon of the acrylic emulsion pressure-sensitive adhesive that occurs when coating the surface of the silicon release paper. Further can be included.

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

  The wetting agent is used to change the hydrophilic pressure-sensitive adhesive to hydrophobic so that the pressure-sensitive adhesive adheres well to the surface of the hydrophobic silicone release paper. And may further contain glycols or alcohols.

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

  The pressure-sensitive adhesive sheet may be a film or sheet for pressure-sensitive adhesive used in product labels, advertisements, printing, chemicals, pharmaceuticals, home appliances, automobiles, stationery labels, and the like. May be 10 to 100 μm, specifically 20 to 30 μm, and has excellent coating properties and sufficient adhesive properties.

  Hereinafter, the present invention will be described with reference to examples. However, the following examples are for illustrating the present invention, and the scope of the present invention is not limited thereto.

  <Example 1>

  300 g of water was placed in a 3 L glass reactor equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet tube and reflux condenser, and the inside of the reactor was replaced with nitrogen while stirring. The temperature was raised to 80 ° C. and maintained for 60 minutes.

  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 n-dodecyl mercaptan were added to a beaker and mixed for 30 minutes. 1000 g of monomer mixture was produced.

  50 g of the monomer mixture was charged into the reactor and stirred for 10 minutes, and then 10 g of 10 wt% ammonium persulfate was charged into the reactor to carry out a reaction for seed production. After the reaction was completed, the mixture was stirred at the same temperature for 1 hour.

  Separately, 950 g of the monomer mixture comprises 19.2 g of 26% by weight sodium polyoxyethylene lauryl ether sulfate, 10.4 g of 45% by weight alkyl diphenyl oxide disulfonate, 2 g of sodium carbonate, 2 g of sodium methylallyl sulfonate, and 220 g of water. The solution was added and stirred with a stirrer to produce a cloudy pre-emulsion.

  The pre-emulsion and 10% by weight ammonium persulfate aqueous solution 150 g were continuously and uniformly introduced into the glass reactor in which the seed was produced for 4 hours, and then 10 g of 10% by weight ammonium persulfate aqueous solution was further added, and then 80 ° C. And maintained at this temperature for 1 hour, and then cooled to room temperature to produce an acrylic emulsion adhesive.

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

  <Example 2>

  For the production of the seed of Example 1, the same procedure as in Example 1 was performed, except that 10 g of the total 1000 g of the monomer mixture was used.

  <Example 3>

  For the production of the seed of Example 1, the same procedure as in Example 1 was performed, except that 30 g of the total 1000 g of the monomer mixture was used.

  <Example 4>

  For the production of the seed of Example 1, the same procedure as in Example 1 was performed, except that 70 g of the total 1000 g of the monomer mixture was used.

  <Example 5>

  For the production of the seed of Example 1, the same procedure as in Example 1 was performed, except that 100 g of the total 1000 g of the monomer mixture was used.

  <Example 6>

  In Example 1, separately, 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 n-dodecyl mercaptan were separately added to the beaker. The procedure was the same as in Example 1 except that 1000 g of the monomer mixture was produced by mixing for 30 minutes.

  <Example 7>

  In Example 1, separately, 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 n-dodecyl mercaptan were added to the beaker. The procedure was the same as in Example 1 except that 1000 g of the monomer mixture was produced by mixing for 30 minutes.

  <Comparative Example 1>

  In Example 1, 300 g of water and 3.8 g of 26% by weight sodium polyoxyethylene lauryl ether sulfate were initially placed in a 3 L glass reactor. Was carried out in the same manner as in Example 1, except that 15.4 g of 26 wt% sodium polyoxyethylene lauryl ether sulfate was added.

  <Comparative example 2>

  In Example 1, the same method as in Example 1 was used except that 9 g of the total 1000 g of the monomer mixture was used for seed production.

  <Comparative Example 3>

  In Example 1, the same method as in Example 1 was used except that 105 g of the total 1000 g of the monomer mixture was used for seed production.

  <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, and for the seed production, out of the total 1000 g of the monomer mixture. Thereafter, 10 g was used, and when preparing a white cloudy pre-emulsion, the same procedure as in Example 1 was performed except that 15.4 g of 26 wt% sodium polyoxyethylene lauryl ether sulfate was added to the monomer mixture. It was.

  <Comparative Example 5>

  In Example 1, 300 g of water and 0.38 g of 26 wt% sodium polyoxyethylene lauryl ether sulfate were initially placed in a 3 L glass reactor, and the total amount of the monomer mixture was 1000 g for seed production. After that, 10 g was used, and at the time of separately producing a cloudy pre-emulsion, the same procedure as in Example 1 was carried out except that 18.82 g of 26 wt% sodium polyoxyethylene lauryl ether sulfate was added to the monomer mixture. It was.

  <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, and for the seed production, out of the total 1000 g of the monomer mixture. In the same manner as in Example 1 except that 100 g was used and then, when separately preparing a cloudy pre-emulsion, 15.4 g of 26 wt% sodium polyoxyethylene lauryl ether sulfate was added to the monomer mixture. It was.

  <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, and for the seed production, out of the total 1000 g of the monomer mixture. After that, 5 g was used, and when preparing a cloudy pre-emulsion, the same procedure as in Example 1 was performed except that 15.4 g of 26 wt% sodium polyoxyethylene lauryl ether sulfate was added to the monomer mixture. It was.

  <Comparative Example 8>

  300 g of water was placed in a 3 L glass reactor equipped with a thermometer, stirrer, dropping funnel, nitrogen inlet tube and reflux condenser, and the inside of the reactor was replaced with nitrogen while stirring. The temperature was raised to 80 ° C. and maintained for 60 minutes.

  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 n-dodecyl mercaptan were added to a beaker and mixed for 30 minutes. A solution consisting of 19.2 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 methylallylsulfonate and 220 g of water is added to 1000 g of the monomer mixture. The mixture was stirred with a stirrer to produce a cloudy pre-emulsion.

  The pre-emulsion and 150 g of 10 wt% ammonium persulfate aqueous solution were continuously and uniformly added to the glass reactor for 4 hours, and then 10 g of 10 wt% ammonium persulfate aqueous solution was further added and then maintained at 80 ° C. Was maintained for 1 hour and then cooled to room temperature to produce an acrylic emulsion pressure-sensitive adhesive.

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

  <Experimental example 1>

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

  * Seed content:% by weight of mixed monomer included in seed production relative to the total weight of mixed monomer

  * Initial surfactant: The amount of surfactant contained in the initial reactor with respect to 100 parts by weight of the mixed monomer

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

  <Experimental example 2>

Manufacture of paper labels coated with adhesive

  The acrylic emulsion adhesives prepared from Examples 1 to 7 and Comparative Examples 1 to 8 were coated on a release paper coated with silicon and dried in an oven at 120 ° C. for 1 minute, and the adhesive layer was 20 μm. It was made to have the thickness of. This was laminated with a polyethylene terephthalate film to make a film label, and cut into a size of 1 inch × 100 mm to produce a film label specimen.

  The adhesive properties of the acrylic emulsion adhesives produced from Examples 1-7 and Comparative Examples 1-8 were tested by the following method, and the results are shown in Table 2 below.

* Measurement of agglomerate content : 100 g of the produced emulsion acrylic pressure-sensitive adhesive was passed through a standard sieve (mesh) with a mesh size of 74 μm according to the process specifications, and the agglomerate remaining on the sieve was washed with distilled water, and the water flowing down was clear Then, it is dried at a temperature of 110 ° C. or lower. The remaining amount after drying is compared with the weight before drying, and the content is converted into a percentage by substituting the weight before and after drying with the above formula.

* Initial adhesion test : Test method FINAT TEST METHOD NO. In accordance with No. 9, a film label specimen of acrylic emulsion adhesive was made into a ring shape, applied to the surface of the glass without applying pressure, and after 5 seconds, 300 mm / min was used using a TA Texture Analyzer instrument. Measured while peeling at speed. (Unit: N / in)

* Peel force test : Test method FINAT TEST METHOD NO. 2, a film label specimen of an acrylic emulsion adhesive was reciprocated twice at a speed of 300 mm / min with a 2 kg roller and adhered onto a glass plate. After aging at room temperature for 20 minutes, TA Texture Measurement was performed using an Analyzer instrument while peeling at 90 ° at a speed of 300 mm / min. (Unit: N / in)

* Cohesive strength test : Test method FINAT TEST METHOD NO. In accordance with No. 8, a film label specimen of an acrylic emulsion adhesive was attached to a stainless steel surface (SUS 304) so that the attachment surface was 1 × 1 inch, and then pressed with a weight of 500 g at 70 ° C. After being stored in the oven for 30 minutes, the weight is removed and allowed to cool at room temperature for 30 minutes. Thereafter, a 1 kg weight is hung from the leading edge of the sheet, and the time for the weight to fall is measured.

* Detergency test : After a film label specimen of acrylic emulsion adhesive was adhered on a glass plate, it was reciprocated twice with a 2 kg roller at a speed of 300 mm / min and pressed. After 1 hour, the test piece was immersed in water for 1 day so that the entire specimen was immersed in water, then taken out, wiped off lightly on the surface, and immediately measured for physical properties by the peeling force test method. (Unit: N / in) The lower the peel force, the better the cleaning performance.

  Referring to Table 1 and Table 2, the acrylic emulsion pressure-sensitive adhesive particles of Examples 1 to 7 are not excessively large or small in size, and the particle distribution is uniform within 10%. Since the stability during polymerization is good, the generation of aggregates is small, the overall physical properties are good, and the detergency is excellent. On the other hand, the acrylic emulsion pressure-sensitive adhesives of Comparative Examples 1 to 8 have excessively large particle sizes. It can be seen that some of the physical properties are reduced because the particle size is too large or small, or the particle distribution is excessively wide.

  Specifically, the acrylic emulsion pressure-sensitive adhesives of Comparative Examples 1 and 6 have a very low detergency because the final particle size is small and the particle distribution is wide by using a surfactant during seed production. did. The acrylic emulsion pressure-sensitive adhesives of Comparative Examples 2 and 3 are used when the content ratio of the monomer mixture used for seed production is out of the claimed content, and the content is excessively small outside the range. , Because the final particle size is large, a large amount of agglomerates are generated due to insufficient stability, and in the case of excessively large agglomerates due to poor stability during seed production, Since the final particle size was also small, it was confirmed that the cleaning property was lowered.

  In addition, the acrylic emulsion pressure-sensitive adhesives of Comparative Examples 4, 5 and 7 have a suitable final particle size by using a surfactant during seed production, but the detergency is reduced due to the wide particle distribution. In the acrylic emulsion pressure-sensitive adhesive of Comparative Example 8, by producing the acrylic emulsion pressure-sensitive adhesive without using a seed, the particle distribution is very wide, so that the detergency is completely lowered. confirmed.

  A person having ordinary knowledge in the field to which the present invention belongs can make various applications and modifications within the scope of the present invention based on the above contents.

  As described above, according to the present invention, a certain amount of an acrylic monomer mixture is non-emulsified and the remaining acrylic monomer mixture is mixed and emulsion polymerized to produce an acrylic polymer. By producing an emulsion adhesive, the final particles of acrylic emulsion adhesive can be uniformly produced in an appropriate size, so that it exhibits excellent adhesive properties and at the same time increases the water absorption during washing and can be easily removed. Has the effect of

Claims (19)

  Based on the total weight of the acrylic monomer mixture, a seed in which 1 to 10% by weight of the acrylic monomer mixture is non-emulsified and 90 to 99% by weight of the acrylic monomer mixture is obtained. An acrylic emulsion pressure-sensitive adhesive, comprising an emulsion-polymerized acrylic emulsion resin, wherein the seed is wrapped with an acrylic emulsion resin.   The acrylic emulsion adhesive according to claim 1, wherein the seed is a non-emulsion polymerized 1 to 5 wt% acrylic monomer mixture based on the total weight of the acrylic monomer mixture. Agent.   The acrylic monomer mixture is i) a (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms, ii) an allyl ester, a vinyl ester, an unsaturated acetate, and an unsaturated nitrile. One or more monomers selected, iii) one or more monomers selected from the group consisting of unsaturated carboxylic acids and hydroxyl group-containing unsaturated monomers, and iv) a crosslinking agent. The acrylic emulsion adhesive according to claim 1.   The acrylic monomer mixture is based on the total weight of the acrylic monomer mixture, i) (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms, ii 1) one or more monomers selected from the group consisting of allyl ester, vinyl ester, unsaturated acetate and unsaturated nitrile, 5 to 35% by weight, iii) consisting of unsaturated carboxylic acid and hydroxyl group-containing unsaturated monomer The acrylic emulsion adhesive according to claim 3, comprising 0.5 to 5% by weight of one or more monomers selected from the group, and iv) 0.1 to 3% by weight of a crosslinking agent. Agent.   The monomer of i) is methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl acrylate, t-butyl methacrylate, pentyl methacrylate, 1 selected from the group consisting of hexyl methacrylate, heptyl acrylate, isooctyl acrylate, octyl methacrylate, 2-ethylhexyl (meth) acrylate, isodecyl acrylate, decyl methacrylate, dodecyl methacrylate, isobornyl methacrylate, and lauryl (meth) acrylate The acrylic emulsion adhesive according to claim 3, wherein the acrylic emulsion adhesive is at least two.   The monomer i) is composed of 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. The acrylic emulsion adhesive according to claim 5.   The monomer of ii) is one or more selected from the group consisting of vinyl acetate, vinyl butanoate, vinyl propionate, vinyl laurate, vinyl pyrrolidone, acrylonitrile and methacrylonitrile, The acrylic emulsion adhesive according to claim 3.   The monomer of iii) is acrylic acid, itaconic acid, maleic anhydride, fumaric acid, crotonic acid, methacrylic acid, ethyl methacrylate, hydroxymethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) ) Acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, hydroxyoctyl (meth) acrylate, hydroxylauryl (meth) acrylate, and hydroxypropylene glycol (meth) acrylate The acrylic emulsion adhesive according to claim 3, wherein the acrylic emulsion adhesive is present.   The acrylic emulsion pressure-sensitive adhesive according to claim 3, wherein the crosslinking agent iv) is a compound having 5 to 15 alkylene oxide groups and 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 seed has a particle size of 100 to 300 nm.   The acrylic emulsion adhesive according to claim 1, wherein the particle size of the acrylic emulsion adhesive is 300 to 800 nm.   The acrylic emulsion adhesive according to claim 1, wherein 95% or more of the particles of the acrylic emulsion adhesive have a particle distribution of ± 10% of an average particle size.   The acrylic emulsion adhesive according to claim 1, wherein the acrylic emulsion adhesive particles have a coefficient of variation of 0.01 to 0.1. It is a manufacturing method of the acrylic emulsion adhesive according to claim 1,
(A) i) 60-90 wt% of (meth) acrylic acid ester monomer having an alkyl group having 1 to 14 carbon atoms, ii) selected from the group consisting of allyl ester, vinyl ester, unsaturated acetate and unsaturated nitrile 5 to 35% by weight of one or more monomers selected, iii) 0.5 to 5% by weight of one or more monomers selected from the group consisting of unsaturated carboxylic acids and hydroxyl group-containing unsaturated monomers And iv) mixing 0.1 to 3% by weight of a crosslinking agent to produce an acrylic monomer mixture;
(B) 1-10 wt% acrylic monomer mixture is added to the reactor based on the total weight of the acrylic monomer mixture, and an initiator is added to produce a seed by non-emulsification polymerization. The process of
(C) Separately, a process of producing a pre-emulsion solution containing 90 to 99% by weight of the 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 manufactured, and then emulsion-polymerizing to prepare an acrylic emulsion adhesive. Manufacturing method.   The acrylic emulsion according to claim 15, wherein the initiator is one or more selected from the group consisting of ammonium or alkali metal persulfate, hydrogen peroxide, peroxide, and hydroperoxide. A method for producing an adhesive.   The method for producing an acrylic emulsion pressure-sensitive adhesive according to claim 15, wherein the seed has a particle size of 100 to 300 nm.   The method for producing an acrylic emulsion pressure-sensitive adhesive according to claim 15, wherein the pre-emulsion solution further comprises water, an electrolyte, and a surfactant.   The adhesive sheet which applies the acrylic emulsion adhesive in any one of Claims 1 thru | or 14 on an adhesive film or sheet | seat, and forms an adhesive layer.