JP5121250B2 - Aqueous emulsion, method for producing aqueous emulsion, and re-emulsifiable resin powder - Google Patents

Description

The present invention relates to an aqueous emulsion. More specifically, it is an aqueous emulsion having excellent protective colloidal power and good viscosity stability when stored at rest, especially excellent in low-temperature viscosity stability that does not thicken even at low temperatures and does not become purine. The present invention relates to an aqueous emulsion and a method for producing the same. Furthermore, the present invention relates to a re-emulsifiable resin powder obtained by removing water from such an aqueous emulsion.

Conventionally, polyvinyl alcohol (hereinafter referred to as PVA) has been used as a protective colloid agent in order to impart mechanical stability and freeze / thaw stability to an aqueous emulsion. However, although the mechanical stability and freezing / thawing stability of the emulsion are improved, the emulsion may be significantly thickened and become pudding, especially when stored at a low temperature such as 0 ° C. there were. In particular, the tendency was more remarkable as the solid content of the emulsion was higher. When the liquid temperature is returned to the room temperature level, it almost returns to the original viscosity level, but this makes it difficult to use in winter field work.
Furthermore, when using the emulsion stored in cans, drums, etc. in a warehouse or the like in the room in winter, there is an inconvenience that the emulsion must be used after returning to room temperature.

In addition, the higher the solid content of the emulsion, the more insufficient the polymerization stability. In particular, polymerization could not be performed at a high solid content exceeding 50% by weight in the emulsion.
Therefore, when PVA is used as a protective colloid agent for an acrylic aqueous emulsion, the solid content in the emulsion needs to be 50% by weight or less, which is problematic in terms of productivity. In addition, the resulting emulsion has insufficient stability and has a problem of thickening with time.

  Therefore, particularly when PVA is used as a protective colloid agent for an acrylic aqueous emulsion, a PVA protective colloid agent capable of polymerizing the solid content in the emulsion even at a high solid content of 50% by weight or more in terms of productivity. There has been a demand for development and development of an aqueous emulsion that does not significantly thicken or become purine even at a low temperature such as 0 ° C.

As such a countermeasure, it has been proposed to use acetoacetyl (CH ₃ COCH ₂ CO—) group-containing PVA as an emulsifying dispersant, which is described in many patent documents. Furthermore, it has also been proposed to use PVA having a 1,2-diol bond in the side chain as an emulsifying dispersant.

  For example, Patent Document 1 contains an active hydrogen group such as an acetoacetate group, a mercapto group, a diacetone acrylamide group, a block character [η] larger than 0.6, and a saponification degree of 95.0 mol%. An aqueous emulsion in which PVA having a higher and lower block property is attached to a polymer is disclosed, and it is described that the resulting aqueous emulsion has good mechanical stability, freezing / thawing stability, and the like.

  However, although an aqueous emulsion having good mechanical stability and freezing / thawing stability has been obtained, the viscosity stability during long-term storage, particularly at a low temperature such as 0 ° C., is significantly increased in viscosity or pudding. It was not satisfactory. Even if it becomes pudding once, it returns to the original state when it is returned to room temperature. However, for example, it was difficult to use it in winter field work in the field of civil engineering and building materials, and an improvement was demanded.

  In Patent Document 2, PVA having a 1,2-diol component in the side chain is used as an emulsifying dispersant, and the polymerization stability is good even at a high solid content such that the solid content in the emulsion exceeds 50% by weight. It has been proposed that an aqueous emulsion with good mechanical stability, freezing / thawing stability, and high-temperature storage stability can be obtained, but it is still satisfactory with respect to suppression of purineation especially at low temperatures such as 0 ° C. It wasn't.

  Patent Document 3 discloses a method for producing an aqueous emulsion in which a PVA is treated with a peroxide in an aqueous medium, followed by emulsion polymerization of a polymerizable monomer as an aqueous emulsion composition having a low temperature fluidity and a high initial adhesiveness. It is disclosed.

  However, in Patent Document 3, the time when PVA is activated with peroxide is before emulsion polymerization of the polymerizable monomer, and there is no description about treatment during emulsion polymerization or after emulsion polymerization. Although an aqueous emulsion having good low-temperature fluidity and good initial adhesiveness has been obtained, it is not sufficient in terms of viscosity stability during long-term storage, in particular, suppression of printing at low temperatures such as 0 ° C. The use of 95 mol% or more PVA with a high degree of conversion was not satisfactory.

JP 2003-277419 A JP 2006-124682 A JP 09-059308 A

  The object of the present invention is to provide an excellent protective colloid which is notably thickened even when stored at 0 ° C. after emulsion polymerization, and does not form a pudding, and has greatly improved viscosity stability at low temperatures. It is an object of the present invention to provide an aqueous emulsion having strength and a method for producing the same. Furthermore, it is providing the re-emulsifiable resin powder which consists of this aqueous emulsion.

  Therefore, as a result of repeated detailed examinations in view of the above circumstances by the present inventors, a good viscosity can be obtained by using an oxidizing agent such as hydrogen peroxide more than before for the aqueous emulsion. An aqueous emulsion having stability was obtained, and it was found that an aqueous emulsion excellent in viscosity stability at a low temperature that does not easily thicken even at low temperatures and does not form a purine form was obtained, and the present invention was completed.

That is, the gist of the present invention is that polymerization is carried out mainly using at least one monomer selected from the group consisting of (meth) acrylic acid ester monomers, styrene monomers and diene monomers. An aqueous emulsion in which the polymer is dispersed with a functional group-containing polyvinyl alcohol resin (A1) having active hydrogen and / or a polyvinyl alcohol resin (A2) having a 1,2-diol bond in the side chain. The present invention relates to an aqueous emulsion obtained by oxidizing an aqueous emulsion containing the polymer with 1 to 15% by weight of an oxidizing agent based on the solid content of the aqueous emulsion, and a method for producing the same.

Furthermore, the present invention relates to a polymerized polymer containing at least one monomer selected from the group consisting of (meth) acrylic acid ester monomers, styrene monomers and diene monomers as a main component. The coalescence is an aqueous emulsion in which a functional group-containing polyvinyl alcohol resin (A1) having active hydrogen and / or a polyvinyl alcohol resin (A2) having a 1,2-diol bond in the side chain is dispersed. viscosity 16 hours after standing at 0 ℃ in minute 45 wt% (V ₀₎ and the viscosity ratio of the viscosity after standing 16 hours at 23 ° C. in a solid content of 45 _{wt% (V 23) (V 0} / V 23) is 20 The following relates to an aqueous emulsion.

The present invention also provides a re-emulsifiable resin powder obtained by removing water from the aqueous emulsion.

  The aqueous emulsion of the present invention has a good viscosity stability even after emulsion polymerization, and has an excellent effect on the viscosity stability at a low temperature that does not easily thicken even at a low temperature such as 0 ° C. Furthermore, the re-emulsifiable resin powder obtained by spray-drying the aqueous emulsion has the same effect as a re-emulsified emulsion. And since these form films with excellent water resistance, they are used in civil engineering and building materials (such as mortar admixtures), paint applications, adhesives and adhesives, textile processing applications, paper processing applications, inorganic binder applications, resins It can be used effectively for reforming applications, soil immobilization applications, cultivation soil binder applications, and the like.

The aqueous emulsion of the present invention was polymerized mainly with at least one monomer selected from the group consisting of (meth) acrylic acid ester monomers, styrene monomers and diene monomers. The polymer is dispersed by a PVA resin (A) , particularly a functional group-containing polyvinyl alcohol resin (A1) having active hydrogen and / or a polyvinyl alcohol resin (A2) having a 1,2-diol bond in the side chain. The aqueous emulsion containing the polymer is oxidized by a 1 to 15% by weight oxidizing agent with respect to the solid content of the aqueous emulsion.

  As the PVA-based resin (A) used in the present invention, a saponified product obtained by saponifying a polyvinyl acetate solution with an alkali or an acid or a derivative thereof is used. Further, vinyl acetate can be copolymerized with vinyl acetate. A saponified product obtained by saponifying a copolymer with a monomer can be used as long as the object of the present invention is not impaired.

  Examples of the monomer copolymerizable with vinyl acetate include olefins (ethylene, propylene, α-butene, α-octene, α-dodecene, α-octadecene, etc.), unsaturated monocarboxylic acids (acrylic acid, methacrylic acid). Acid, crotonic acid, etc.) or esters or salts thereof, unsaturated polycarboxylic acids (maleic acid, fumaric acid, itaconic acid, etc.) or partial or complete esters or salts or anhydrides thereof, unsaturated sulfonic acids (ethylene sulfone) Acid, allyl sulfonic acid, methallyl sulfonic acid and the like) or salts thereof, amide (acrylamide, methacrylamide, etc.), nitrile (acrylonitrile, methacrylonitrile, etc.), vinyl ether, vinyl ketone, vinyl chloride and the like.

  Saponification is carried out by dissolving a polymer such as polyvinyl acetate in an alcohol or hydrous alcohol and using an alkali catalyst or an acid catalyst. Examples of the alcohol include C1-C6 saturated alcohols such as methanol, ethanol, propanol, and tert-butanol. Among these, methanol is particularly preferably used. The concentration of the polymer in the alcohol is appropriately selected depending on the viscosity of the system, but is usually selected from the range of 10 to 60% by weight.

  Catalysts used for the saponification include sodium hydroxide, potassium hydroxide, sodium methylate, sodium ethylate, potassium methylate, alkali metal hydroxides such as lithium methylate, alkali catalysts such as alcoholate; sulfuric acid, Examples include acid catalysts such as hydrochloric acid, nitric acid, metasulfonic acid, zeolite, and cation exchange resin. The amount of the saponification catalyst used is appropriately selected depending on the saponification method, the target degree of saponification, and the like. When an alkali catalyst is used, it is usually 0.1 to 30 per 1 mol of the PVA resin. It is preferably a millimolar, more preferably 2 to 17 millimolar. The reaction temperature for the saponification reaction is not particularly limited, but is preferably 10 to 60 ° C, more preferably 20 to 50 ° C.

  As the PVA resin (A) used in the present invention, those having a saponification degree of 80 mol% or more, preferably 85 mol% or more, and a polymerization degree of 10 to 3000, preferably 20 to 2000 are used.

In the present invention, among the above-mentioned PVA resins (A), various modified PVA resins can be used from the viewpoint of further enhancement of functionality. In particular, graft properties are improved, and protective colloid properties are improved. From the point that becomes favorable, a functional group-containing PVA resin (A1) having active hydrogen is used.

  20-1000 are preferable, as for the polymerization degree of the functional group containing PVA-type resin (A1) which has active hydrogen, More preferably, it is 200-800, More preferably, it is 200-500. If the degree of polymerization is too small, there is a tendency not to have protective colloid properties, and furthermore, it is not easy to industrially produce a PVA resin having a degree of polymerization that is too small. If it is too large, the viscosity of the emulsion tends to be too high, or the polymerization stability of the emulsion tends to be reduced.

  Furthermore, the saponification degree of the functional group-containing PVA resin (A1) having active hydrogen is preferably 95 to 100 mol%, more preferably 97 to 99.8 mol%. If the degree of saponification is too small, the stability of the emulsion during polymerization tends to be extremely reduced, making it difficult to obtain the desired aqueous emulsion.

  The modification amount of the functional group having active hydrogen is usually preferably 0.01 to 20 mol%, particularly preferably 0.01 to 6 mol%, more preferably 0.03 to 4.5 mol%, Preferably it is 0.03-2 mol%, Most preferably, it is 0.03-1 mol%. If the amount of modification is too small, the protective colloid properties will decrease and polymerization stability will decrease, and if the solid content is high, gelation will occur during the reaction, and if it is too high, the polymerization stability of the emulsion will decrease. Tend.

  Examples of the functional group having active hydrogen include an acetoacetyl group, a diacetone acrylamide group, an amino group, and a mercapto group. Among these, an acetoacetyl group is preferable from the viewpoint of graft reactivity.

  Examples of the method of introducing an acetoacetyl group into the PVA resin include a method of reacting a PVA resin and diketene, a method of reacting a PVA resin and acetoacetate, etc., but the production process is simple, and From the viewpoint of obtaining a high-quality acetoacetyl group-containing PVA resin, it is preferable to produce the PVA resin and diketene by a reaction method. Furthermore, the method of reacting the PVA resin with diketene is also preferred because it has the advantage that the amount of diketene used is small and the reaction yield of diketene is improved.

  When the functional group-containing PVA resin (A1) having active hydrogen is an acetoacetyl group-modified PVA resin, the acetoacetylation degree is preferably 0.01 to 5 mol%, more preferably 0.1 to 3 mol. %, More preferably 0.3 to 1 mol%. If the degree of acetoacetylation is too small, the water resistance and mechanical strength of the emulsion tend to be insufficient, and if too large, the polymerization stability of the emulsion tends to be lowered.

The particle size of the acetoacetyl group-containing PVA resin is preferably 20 to 5000 μm, and more preferably 44 to 1680 μm. If the particle size is too small, the particles are likely to be fused by heat of reaction, and further post-treatment such as washing and drying tends to be difficult. If the particle size is increased, the PVA resin particles and diketene used for the acetoacetylation reaction There is a tendency for the contact to become non-uniform and to reduce the reaction rate of the diketene.
The particle size of the acetoacetyl group-containing PVA resin can be adjusted by adjusting with a standard sieve or air classification after the production of the PVA resin.

As a method for introducing a diacetone acrylamide group into a PVA resin, it can be obtained by copolymerization of diacetone acrylamide and vinyl acetate and then saponification. The copolymerization of diacetone acrylamide and vinyl acetate is not particularly limited, but the polymerization rate is adjusted according to the HANNA formula (reactivity ratio: diacetone acrylamide; r1 = 14.8, vinyl acetate; r2 = 0.06). Accordingly, it is preferable to charge diacetone acrylamide. By uniformly modifying diacetone acrylamide, it becomes easy to obtain a PVA-based resin having a low acetoxy group (CH ₃ COO—) blocking property.
Next, saponification is carried out, but the saponification may be carried out in the same manner as in the production of the acetoacetyl group-containing PVA resin.

  The diacetone acrylamide group content of the diacetone acrylamide group-containing PVA resin thus obtained is preferably from 0.1 to 15 mol%, more preferably from 0.5 to 10 mol%, still more preferably from 1 to 8 mol%. If the content is too small, the effects of the present invention tend not to be sufficiently obtained. On the other hand, if the content is too large, the water solubility of the PVA resin decreases or the polymerization stability when obtaining an aqueous emulsion is obtained. Tends to decrease (coarse particles increase, emulsion viscosity becomes too high, etc.).

As a method for introducing a mercapto group into a PVA-based resin, it can be obtained by saponification after polymerization in the presence of a compound having a mercapto group as a chain transfer agent during polymerization of vinyl acetate. As a compound having such a mercapto group, the following general formula (1):
R ¹ —CO—SH (1)
(Wherein R ¹ is an alkyl group having 2 to 15 carbon atoms)
Examples thereof include organic thiolic acids such as thioacetic acid, thiopropionic acid, thiobutyric acid, and thiovaleric acid.

  When polymerizing vinyl acetate using a compound having a mercapto group as described above as a chain transfer agent, according to the following formula (I), a chain transfer agent having a mercapto group corresponding to the desired degree of polymerization (for example, organic The initial charge amount of thiolic acid) is determined and polymerization is started, and then the chain transfer agent is additionally charged according to the following formula (II) in accordance with the consumption rate of the chain transfer agent.

1 / P = Cm + Cs ([S] / [M]) + Cx ([X] / [M]) (I)
Additional charge = Cx ([X] / [M]) · Rp (II)
Here, P is the degree of polymerization, Cm is the chain transfer constant for the monomer, Cs is the chain transfer constant for the solvent, Cx is the chain transfer constant of the chain transfer agent, [S] is the solvent concentration (mol / l), and [M] is Monomer concentration (mol / l) and Rp are polymerization rates (mol / l / sec). T represents the polymerization temperature (K).

  Next, saponification is carried out, but the saponification may be carried out in the same manner as in the production of the acetoacetyl group-containing PVA resin.

In the present invention, among the PVA-based resins (A), the side chain of the PVA-based resin is particularly preferably 1,2- in terms of increase in solid content (up) of emulsion, ease of polymerization, and the like. A PVA resin (A2) having a diol bond is used.

  The PVA resin (A2) having a 1,2-diol bond in the side chain is, for example, (a) a method of saponifying a copolymer of vinyl acetate and 3,4-diacetoxy-1-butene, ) A method of saponifying and decarboxylating a copolymer of vinyl acetate and vinyl ethylene carbonate, (c) Saponifying a copolymer of vinyl acetate and 2,2-dialkyl-4-vinyl-1,3-dioxolane And (d) a method of saponifying a copolymer of vinyl acetate and glycerin monoallyl ether, and the like.

  The saponification degree of the PVA resin (A2) having a 1,2-diol bond in the side chain is preferably 85 to 100 mol%, more preferably 90 to 99.8 mol%. If the degree of saponification is too small, the stability of the emulsion during polymerization tends to decrease, making it difficult to obtain the desired aqueous emulsion.

  Moreover, it is preferable that the 1, 2- diol bond amount of the side chain of this PVA-type resin (A2) is 1-15 mol%, More preferably, it is 1-12 mol%, More preferably, it is 2-10 mol%. More particularly preferably, it is 2 to 8 mol%. If the content of the 1-2 diol component is too small, the mechanical stability of the emulsion and the water resistance of the film tend to decrease. If the content is too large, the stability during polymerization decreases, and the non-volatile content is high and stable. It tends to be difficult to obtain an emulsion.

  The polymerization degree of the PVA resin (A2) having a 1,2-diol bond in the side chain is preferably 50 to 2500, more preferably 100 to 1700, still more preferably 100 to 1000, and particularly preferably 200 to 500. . If the degree of polymerization is too small, it tends to be difficult to industrially produce a PVA resin, and if it is too large, the viscosity of the emulsion tends to be too high, or the polymerization stability of the emulsion tends to decrease.

  Moreover, you may use together the PVA-type resin containing group which has an anion as PVA-type resin (A) used by this invention. Examples of the group having an anion include a sulfonic acid group, a carboxylic acid group, and a phosphoric acid group, but among these, regardless of the pH in the emulsion, a stable and strong charge repulsion can be obtained. A sulfonic acid group is preferred.

The aqueous emulsion of the present invention comprises the functional group-containing PVA resin (A1 ) having active hydrogen and / or the polyvinyl alcohol resin (A2) having a 1,2-diol bond in the side chain, and other if necessary. A monomer comprising at least one monomer selected from the group consisting of a (meth) acrylic acid ester monomer, a styrene monomer and a diene monomer in the presence of a PVA resin. The aqueous emulsion containing the polymer is polymerized, preferably emulsion polymerized, and obtained by subjecting it to an oxidation treatment using an oxidizing agent in an amount of 1 to 15% by weight based on the solid content of the aqueous emulsion. .
The oxidation treatment with an oxidizing agent is preferably performed during and / or after the polymerization of the polymer.

  Here, the main component means that the following monomer is contained most in the total weight of the polymer, preferably 50% by weight or more.

  Examples of (meth) acrylic acid ester monomers include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, (meth) Aliphatics such as n-butyl acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (meth) acrylate Examples include (meth) acrylic acid alkyl esters and aromatic (meth) acrylic acid esters such as benzyl (meth) acrylate. In addition, in the above, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester.

  Examples of the styrene monomer include styrene and α-methylstyrene.

  Examples of the diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene, 1,3 or 2,3-dimethyl-1,3-butadiene, and 2-chloro-1,3-butadiene. Examples include butadiene.

  The monomers may be used alone or in combination of two or more.

Moreover, the following monomers can be used together in the range which does not inhibit the objective of this invention.
Vinyl ester monomers; vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, versatic acid Vinyl etc.

Olefin monomer; ethylene, propylene, 1-butene, isobutene, and the like.
Halogenated olefin monomers; vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, etc.

  Amide monomers; (meth) acrylamide, N-methylolacrylamide, N, N-dimethyl (meth) acrylamide, (meth) acrylamide-2-methylpropanesulfonic acid (salt), diacetone (meth) acrylamide, maleic acid amide A compound having a branched or straight chain alkylene group having 1 to 5 carbon atoms such as maleimide.

Nitrile monomers; (meth) acrylonitrile and the like.
Vinyl ether monomers; methyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, stearyl vinyl ether, and the like.

Allyl monomers; allyl acetate, allyl chloride, etc.
Carboxyl group-containing monomers; (meth) acrylic acid, crotonic acid, fumaric acid, maleic anhydride, itaconic acid, and esters thereof.
Sulfonic acid group-containing monomers; ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid and the like.

Silyl group-containing monomers; vinyltrimethoxysilane, vinyltriethoxysilane, etc.
Hydroxyl group-containing monomers; hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, polyethylene glycol (meth) acrylate, and the like.
Epoxy group-containing monomer; glycidyl (meth) acrylate, allyl glycidyl ether, etc.

Amino group-containing monomer; N-diethylaminoethyl (meth) acrylate and the like.
Sulfonic acid group-containing monomers; vinyl sulfonic acid, vinyl styrene sulfonic acid and the like.
Phosphoric acid group-containing monomers; vinyl phosphate, acid phosphoxyethyl (meth) acrylate, etc.
Acetoacetyl group-containing monomers; acetoacetoxyethyl (meth) acrylate, acetoacetoxypropyl (meth) acrylate, acetoacetic acid vinyl ester, and the like.

  Monomers having two or more vinyl groups in the molecular structure; divinylbenzene, ethylene glycol di (meth) acrylate, 1,2-propylene glycol di (meth) acrylate, 1,6 hexanediol di (meth) acrylate, neo Bifunctional or higher monomers such as pentyl glycol di (meth) acrylate, and trifunctional or higher functional monomers such as trimethylolpropane tri (meth) acrylate.

  As the monomer, an aqueous emulsion obtained by using an acetoacetyl group-containing monomer, a silyl group-containing monomer, an epoxy group-containing monomer, an amide monomer, or a carboxyl group-containing monomer It is preferable in terms of improving water resistance, adhesion, film strength / elongation, solvent resistance, and the like. Particularly preferred are acetoacetyl group-containing monomers and silyl group-containing monomers.

  The aqueous emulsion of the present invention comprises a (meth) acrylic acid ester monomer, a styrene monomer, and a PVA resin aqueous solution in which water is dissolved in the presence of a polymerization initiator. It is prepared by temporarily or continuously adding at least one monomer selected from the group consisting of diene monomers and other monomers, followed by heating and stirring.

  The aqueous emulsion obtained by the above method is such that at least a part of the PVA resin (A) used for the dispersion stabilization is grafted to the polymer, and the emulsion has excellent mechanical stability, freezing / thawing stability, This is preferable in terms of obtaining stability during low-temperature storage and excellent water resistance of the film.

  The graft ratio is preferably 60% by weight or more, and more preferably 70 to 100% by weight. If the graft ratio is too small, mechanical stability, freezing / thawing stability, and water resistance of the film tend to be lowered.

The graft ratio is calculated by the following method.
<Graft rate measurement>
The obtained aqueous emulsion was dried at 40 ° C. for 16 hours to prepare a film of about 0.5 mm, left to stand at 23 ° C. × 65% RH for 24 hours, and then the film was heated in boiling water for 8 hours. Extraction is then performed for 8 hours with acetone, and the absolute dry weight of the film before extraction is W1 (g) and the absolute dry weight of the film after extraction is W2 (g). Rate.
Graft ratio (% by weight) = (W2) / (W1) × 100
Film dry weight after extraction (W2): Film weight when the sample after extraction was completely dried at 105 ° C. for 1 hour.
Film dry weight before extraction (W1): The film weight when a pre-extraction sample different from the extraction test sample was previously dried at 105 ° C. for 1 hour.

  As a method for preparing the PVA-based resin aqueous solution, it is preferable that the PVA-based resin (A) is added in an amount of 2 to 20 parts by weight, more preferably 3 to 15 parts by weight with respect to 100 parts by weight of water. And can be prepared by heating and stirring. If the amount of the PVA resin (A) added is too small, a desired solid emulsion may not be obtained. If the amount is too large, the viscosity tends to increase at the time of dissolution, and the subsequent workability tends to be significantly reduced.

  The heating and stirring conditions vary depending on the scale and type of the stirring blade, and thus cannot be generally stated. For example, it is preferably 50 to 100 ° C., 30 to 300 rpm, and 20 minutes to 3 hours, preferably 70 to 90 ° C. 150-250 rpm, 30 minutes to 1 hour is more preferable.

  The amount of the PVA resin (A) used is somewhat different depending on the type and the resin content of the emulsion, but is usually preferably 0.5 to 20% by weight, more preferably based on the whole reaction system. 1 to 10% by weight, more preferably 2 to 8% by weight. If the amount used is too small, it tends to be difficult to maintain the polymer particles in a stable emulsified state, while if too large, the emulsion viscosity tends to increase and workability tends to decrease.

  As the polymerization initiator, potassium persulfate, ammonium persulfate, potassium bromate and the like are usually used alone or in combination, or in combination with acidic sodium sulfite. Water-soluble redox polymerization initiators such as hydrogen peroxide-tartaric acid, hydrogen peroxide-iron salt, hydrogen peroxide-ascorbic acid-iron salt, hydrogen peroxide-longalit, hydrogen peroxide-longalit-iron salt Is also used. Specifically, a catalyst comprising an organic peroxide and a redox system such as “Kayabutyl B” (manufactured by Kayaku Akzo Co., Ltd.) or “Kayabutyl A-50C” (manufactured by Kayaku Akzo Co., Ltd.) may be used. it can. Among them, it is preferable to use a persulfate because the graft polymerization with the PVA resin (A) is promoted and the polymerization stability is improved. Of the persulfates, ammonium persulfate is particularly preferred. The method for adding the polymerization initiator is not particularly limited, and a method of adding all at once in the initial stage, a method of adding continuously as the polymerization progresses, or the like can be employed.

  During the polymerization, it is preferable to maintain the pH at 3 to 8 in terms of improving the polymerization stability of the emulsion. More preferably, the pH is 3-6. If the pH is too low, the polymerization stability of the emulsion tends to be insufficient, and if the pH is too high, the polymerization rate tends to extremely decrease. In order to maintain the pH within the above range, it is preferable to add a buffer before and / or during the polymerization. When it is added during the polymerization, it may be added in portions or continuously.

  Although it does not specifically limit as a buffering agent, Sodium acetate, potassium acetate, sodium carbonate, sodium phosphate, etc. can be used, It is preferable to use especially sodium acetate aqueous solution.

Furthermore, when an iron compound is contained in the emulsion polymerization system, it is preferable that the controllability of the emulsion polymerization can be further improved, aggregation or the like hardly occurs during the emulsion polymerization, and the polymerization stability is remarkably improved.
Such an iron compound is not particularly limited, but is preferably at least one iron compound selected from iron oxide, ferrous chloride, ferrous sulfate, ferric chloride, ferric nitrate or ferric sulfate, Of these, ferric chloride is particularly preferred.

  The content of the iron compound is preferably 1 to 1000 ppm, more preferably 5 to 200 ppm, and particularly preferably 5 to 100 ppm based on the aqueous emulsion after polymerization. If the content of the iron compound is too small, the polymerization tends not to proceed sufficiently, and if it is too much, the viscosity stability of the emulsion tends to decrease.

  When adding an iron compound, it is preferable to add the iron compound before the polymerization, but it may be added during the polymerization or at the end of the polymerization. In addition, when the iron compound is contained, it may be prepared from an iron compound contained in the water used.

  In the emulsion polymerization, a water-soluble polymer, a nonionic active agent, an anionic active agent, a cationic active agent, etc. can be used in combination as an emulsion dispersion stabilizer.

  Examples of water-soluble polymers include non-modified PVA resins other than PVA resins (A), PVA resins such as formalized products, acetalized products, butyralized products, urethanized products, vinyl esters, and vinyl esters. Examples thereof include a saponified product of a copolymer with a polymerizable monomer. Monomers copolymerizable with vinyl esters include olefins such as ethylene, butylene, isobutylene, α-octene, α-dodecene, α-octadecene, acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride Unsaturated acids such as itaconic acid, salts thereof, mono- or dialkyl esters, nitriles such as acrylonitrile and methacrylonitrile, amides such as acrylamide, diacetone acrylamide and methacrylamide, ethylene sulfonic acid, allyl sulfonic acid, meta Examples thereof include olefin sulfonic acids such as allyl sulfonic acid, or salts thereof, alkyl vinyl ethers, vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, and vinylidene chloride.

  In addition, cellulose derivatives such as methyl cellulose, ethyl cellulose, hydroxymethyl cellulose, hydroxypropyl methyl cellulose, hydroxybutyl methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, aminomethyl hydroxypropyl cellulose, aminoethyl hydroxypropyl cellulose, starch, tragacanth, pectin, Glue, alginic acid or its salt, gelatin, polyvinylpyrrolidone, polyacrylic acid or its salt, polymethacrylic acid or its salt, polyacrylamide, polymethacrylamide, vinyl acetate and maleic acid, maleic anhydride, acrylic acid, methacrylic acid, itacone Copolymers of unsaturated acids such as acid, fumaric acid, crotonic acid, styrene and unsaturated acids Polymers, copolymers of vinyl ether and the unsaturated acid and the like salts or esters of the copolymer can also be used as a water-soluble polymer.

  Nonionic activators include, for example, polyoxyethylene-alkyl ether type, polyoxyethylene-alkylphenol type, polyoxyethylene-polyhydric alcohol ester type, ester of polyhydric alcohol and fatty acid, oxyethylene / oxypropylene block Examples include polymers.

Examples of anionic activators include higher alcohol sulfates, higher fatty acid alkali salts, polyoxyethylene alkylphenol ether sulfates, alkylbenzene sulfonates, naphthalene sulfonate formalin condensates, alkyl diphenyl ether sulfonates, and dialkyl sulfosuccinates. And higher alcohol phosphoric acid ester salts.
Examples of the cationic activator include higher alkylamine salts.

  Furthermore, in the emulsion polymerization, a plasticizer such as phthalate ester and phosphate ester, a pH adjuster such as sodium carbonate, sodium acetate, sodium phosphate, and aqueous ammonia can be used in combination.

  As for superposition | polymerization temperature, 70-90 degreeC is preferable, More preferably, it is 75-87 degreeC, More preferably, it is 80-85 degreeC. If the polymerization temperature is too low, graft polymerization with the PVA resin is not promoted and the polymerization stability tends to be lowered. If it is too high, the protective colloid property of the PVA resin is lowered, or the emulsion polymerization is stabilized. There is a tendency to become difficult to progress.

In the present invention, the aqueous emulsion containing the obtained polymer is subjected to a heat treatment using an oxidizing agent of 1 to 15% by weight with respect to the solid content of the aqueous emulsion, and is subjected to an oxidation treatment, whereby the emulsion is obtained. and excellent protective colloid force, viscosity stability during good standing storage, in particular can be obtained an aqueous emulsion having a viscosity stability such not be thickened hard pudding-like at low temperatures.

  This is due to the effect that the 1,2-glycol bond site of the main chain of the PVA resin in the system is cleaved by the heat treatment with the oxidizing agent to reduce the degree of polymerization and the charge repulsion effect of the carboxylic acid generated by the cleaving, This is presumably because the entanglement between the PVA-based resins is suppressed.

  Such an oxidizing agent is not particularly limited and includes, for example, hydrogen peroxide, iodic acid, potassium permanganate, etc. Among them, hydrogen peroxide is preferable from the viewpoint of safety after decomposition.

  The oxidation treatment agent may be added at any time during the polymerization and / or after the polymerization, but is preferably after the emulsion polymerization particularly in that the polymerization reaction is not adversely affected. Before emulsion polymerization, the polymerization reaction will be adversely affected. Moreover, if it adds after emulsion polymerization, there will be no restriction | limiting in particular, However, It is preferable to add within 24 hours after emulsion polymerization, Furthermore, it is more preferable to add within 1-2 hours. If it is added during emulsion polymerization, the polymerization rate is preferably 90% or more, more preferably 95% or more, and particularly preferably 98% or more. It is preferable at the point that stability does not fall.

  Moreover, as an addition method of an oxidizing agent, even if it adds continuously or may be added collectively, it is not specifically limited.

  The addition amount of the oxidizing agent is preferably 1 to 15% by weight, more preferably 2 to 10% by weight, and further preferably 3 to 8% by weight with respect to the solid content of the aqueous emulsion. If the amount added is too small, there is a tendency that the effect of inhibiting thickening and purineation is suppressed particularly at low temperatures, and if it is too large, physical properties such as water resistance of the film tend to deteriorate.

  The oxidation treatment is performed by heating, for example, and the heating temperature is not particularly limited, but is preferably performed at 50 to 95 ° C, more preferably 70 to 90 ° C, and further preferably. Is 80-87 ° C. If the heat treatment temperature is too low, the effect tends to be difficult to obtain, and if it is too high, the physical properties tend to deteriorate.

  The oxidation treatment time can be appropriately adjusted. For example, 0.5 to 5 hours is preferable, and 1 to 3 hours is more preferable. If the heat treatment time is too long, the water resistance of the film tends to be lowered, and if it is too short, the effect of suppressing the increase in viscosity at the low temperature and the effect of suppressing the purification tend to be lowered.

  Thus, the aqueous emulsion of the present invention can be obtained. In the present invention, the average particle diameter of the aqueous emulsion is usually 0.05 to 5 μm, and the film forming property and the adhesiveness with inorganic materials such as cement and quartz sand are used. In consideration of the balance between the solid content and the viscosity of the aqueous emulsion, the thickness is preferably 0.2 to 1.5 μm, more preferably 0.3 to 0.7 μm.

  In addition, the glass transition temperature of the polymer in the aqueous emulsion is usually preferably −30 to + 15 ° C. from the viewpoints of various adhesive applications and applications as an admixture for cement and mortar and the elasticity of the film. In particular, it is preferably −20 to + 10 ° C.

  Furthermore, the solid content of the aqueous emulsion is preferably 40 to 55% by weight and more preferably 45 to 50% by weight from the viewpoints of drying property and coating property.

Thus, the aqueous emulsion of the present invention oxidized with a specific amount of oxidizing agent is very excellent in viscosity stability, for example, the viscosity after standing at 23 ° C. for 16 hours at a solid content of 45% by weight. (V ₂₃ ) usually indicates 100 to 2000 mPa · s, preferably 200 to 1000 mPa · s. Furthermore, it is very excellent in viscosity stability when left at low temperature. For example, the viscosity (V ₀ ) after standing at 0 ° C. for 16 hours at a solid content of 45% by weight is usually 300 to 10000 mPa · s. s, preferably 500 to 5000 mPa · s.

In the present invention, the viscosity ratio (V ₀ ) after standing at 0 ° C. for 16 hours at a solid content of 45% by weight and the viscosity (V ₂₃ ) after standing at 23 ° C. for 16 hours at a solid content of 45% by weight ( V ₀ / V ₂₃ ) is preferably 20 or less, more preferably 10 or less. If the viscosity ratio (V ₀ / V ₂₃ ) is too large, it is difficult to handle in a low temperature state, and it may be difficult to use on site.

  Moreover, in this invention, the resin powder excellent in re-emulsification property can be obtained by removing a water | moisture content from said aqueous emulsion. The method for removing water is not particularly limited, and methods such as spraying / heating drying, spraying / air blowing drying, freeze drying, and the like can be used. Industrially, spraying / heating drying is suitably performed. For spraying and heat drying, a normal spray dryer for spraying and drying a liquid can be used. Depending on the type of spraying, there are a disk type and a nozzle type, and any type is used. Hot air or heated steam is used as the heat source.

  The spray drying conditions are appropriately selected depending on the size and type of the spray dryer, the emulsion concentration, the viscosity, the flow rate, and the like. The drying temperature is usually preferably 80 to 150 ° C, more preferably 100 to 140 ° C. If the drying temperature is too low, the film cannot be sufficiently dried. If the drying temperature is too high, the polymer is fused by heat, and there is a possibility that re-emulsification is lowered and the resin is deteriorated.

  In addition, since the re-emulsifiable resin powder may be agglomerated and aggregated during spray drying or during storage, an anti-caking agent is added to improve storage stability. It is preferable. The anti-caking agent may be added to the aqueous emulsion resin powder after spray drying and mixed uniformly. However, when the aqueous emulsion is spray-dried, the aqueous emulsion may be sprayed in the presence of the anti-caking agent. From the viewpoint of uniform mixing and the effect of preventing caking. It is particularly preferred to spray and dry both at the same time.

  As the anti-caking agent, fine inorganic powder is preferable, and examples thereof include calcium carbonate, clay, anhydrous silicic acid, aluminum silicate, white carbon, talc, and alumina white. In particular, anhydrous silicic acid, aluminum silicate, calcium carbonate and the like having an average particle size of about 0.01 to 0.5 μm are preferable. Although the usage-amount of an anti-caking agent is not specifically limited, 2-30 weight% is preferable with respect to resin powder, More preferably, it is 5-20 weight%.

  The aqueous emulsion of the present invention thus obtained has an excellent protective colloidal force and good viscosity stability during storage, and does not easily thicken even at low temperatures, and does not become purine-like without impairing conventional physical properties. It occupies if possible.

  Since the aqueous emulsion of the present invention forms a film with excellent water resistance, it is used for civil engineering and building materials (such as mortar admixtures), coatings, adhesives and adhesives, textile processing, paper processing, and inorganic binders. It is useful for applications, resin modification applications, soil immobilization applications, cultivation soil binder applications, cosmetic applications, and the like.

  When the aqueous emulsion of the present invention is used in an adhesive composition, in addition to the aqueous emulsion, the adhesive composition includes a water-soluble polymer such as a PVA resin, a cross-linking agent such as a polyvalent isocyanate compound, a water-resistant agent, and a pigment. , Dispersants, antifoaming agents, oil agents, viscosity modifiers, tackifiers, thickeners, water retention agents, and the like.

  The adhesive composition is used as an adhesive for corrugated cardboard, interleaf, paper tube, wood, plywood, structural veneer laminate (LVL), particleboard, laminated wood, fiberboard, etc. Can be used.

  The aqueous emulsion of the present invention is also very useful as a cement / mortar admixture (cement base conditioner, inorganic finishing agent, mortar sealer / primer mortar curing agent), stock solution for re-emulsifiable resin powder, and the like.

  When used as an admixture for cement and mortar, for example, considering the physical properties of the resulting cured product, the aqueous emulsion and the re-emulsifiable resin powder are both 1 to 3 in terms of solid content with respect to 100 parts by weight of cement and mortar. It is preferable to add 30 parts by weight, and more preferably 2 to 15 parts by weight. Considering economical aspects, 2 to 10 parts by weight is preferable, and 3 to 7 parts by weight is more preferable.

  As a method of mixing an aqueous emulsion into cement or mortar, a method of mixing (compounding) with cement or mortar in advance, a method of mixing (compounding) with water in advance, cement, mortar, water, and an aqueous emulsion at the same time. The method of mixing etc. is mention | raise | lifted.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist.
In the examples and comparative examples, “parts” represent “parts by weight”.

  Each aqueous emulsion obtained in Examples and Comparative Examples was evaluated in the following manner.

<Average particle size>
The average particle size was measured using a “HORIBA laser diffraction / scattering particle size distribution analyzer LA-910”.

<Each viscosity of an aqueous emulsion at 0 ° C. and 23 ° C. and a viscosity ratio (V ₀ / V ₂₃ )>
An aqueous emulsion prepared with a solid content of 45% was placed in a 200 ml glass bottle, allowed to stand at 23 ° C. for 16 hours, and the viscosity (mPa · s) was measured with a B-type viscometer (BL type, 12 rpm) (viscosity V ₂₃ ). . The aqueous emulsion was allowed to stand at 0 ° C. for 16 hours, and the viscosity (mPa · s) at 0 ° C. was measured (viscosity V ₀ ).
Further, the viscosity ratio (V ₀ / V ₂₃ ) was calculated from the obtained viscosity V ₂₃ and viscosity V ₀ .

<Evaluation of emulsion state after standing at 0 ° C.>
An aqueous emulsion having a solid content of 45% was placed in a 200 ml glass bottle, and the emulsion state when allowed to stand at 0 ° C. for 16 hours was evaluated according to the following criteria.
◎ ・ ・ ・ Not thickened.
○ ・ ・ ・ Thickened but fluid enough.
Δ: Soft pudding.
X: Hard pudding.

Example 1
In a 1 L separable flask equipped with a stirrer, reflux condenser, dropping funnel and thermometer, water 390 g, acetoacetyl group-containing PVA (saponification degree 97.0 mol%, polymerization degree 300, acetoacetylation degree 0.5 mol%, Nippon Synthetic Chemical Industry Co., Ltd.) (23 g), sodium acid sulfite (0.7 g), sodium acetate (1.2 g) as a pH adjuster was charged and stirred at 85 ° C. for 1 hour (stirring speed: 230 rpm), containing acetoacetyl group PVA was dissolved. After confirming that the acetoacetyl group-containing PVA aqueous solution was stable at 83 ° C., a polymerization monomer (methyl methacrylate / n-butyl acrylate / acetoacetic acid monomer = 44.8 / 54.7 / 0.5 (weight ratio)) 32.5 g was added all at once and stirred well for 5 minutes, then 5.3 g of 5% aqueous ammonium persulfate solution was added all at once to initiate initial polymerization, which was carried out for 45 minutes, and thereafter 82-83. The remaining polymerization monomer 293 g was added dropwise at 3.5 ° C. over 3.5 hours, and 10.7 g of 5% ammonium persulfate aqueous solution was added in 30 portions every 7 minutes for polymerization. After 1.8 g of ammonium sulfate aqueous solution was added in two portions and subjected to late polymerization at 82 ° C. for 90 minutes, 14 g of 30% aqueous hydrogen peroxide solution was added (4 parts per 100 parts solid content of the aqueous emulsion). ) And continued stirring for 60 minutes at 85 ° C. An aqueous emulsion (1) of a copolymer of methyl methacrylate / n-butyl acrylate / acetoacetic acid monomer having a solid content of 45% was obtained (iron content 43 ppm) The evaluation results of the obtained aqueous emulsion are shown in Table 1.
The calculated glass transition temperature (Tg) of the polymer comprising this main polymerization monomer (methyl methacrylate / n-butyl acrylate = 44.8 / 54.7 = 45.0 / 55.0 (weight ratio)) is When the Tg of each homopolymer was −52 ° C. and + 105 ° C., it was −1 ° C. The graft ratio of the obtained aqueous emulsion was 75%.

Example 2
The same procedure as in Example 1 was carried out except that the amount of 30% hydrogen peroxide aqueous solution added was changed to 28 g (8 parts with respect to 100 parts of the solid content of the aqueous emulsion) (however, the amount of charged water was 380 g). % Aqueous emulsion (2) of a copolymer of methyl methacrylate / n-butyl acrylate / acetoacetic acid monomer was obtained (iron content 43 ppm). The evaluation results of the obtained aqueous emulsion are shown in Table 1.
The calculated glass transition temperature (Tg) of the polymer composed of the main polymerization monomer was −1 ° C. as in Example 1.

Example 3
Add 30g hydrogen peroxide aqueous solution 14g (4 parts to 100 parts solid content of aqueous emulsion) 30 minutes before the end of 90 minutes of late polymerization (time of polymerization rate 95% or more) Example 1 was carried out in the same manner as in Example 1 except that an aqueous emulsion (3) of a copolymer of methyl methacrylate / n-butyl acrylate / acetoacetic acid monomer having a solid content of 45% (iron content 43 ppm) was obtained. ). The evaluation results of the obtained aqueous emulsion are shown in Table 1.
The calculated glass transition temperature (Tg) of the polymer composed of the main polymerization monomer was −1 ° C. as in Example 1.

Example 4
An aqueous emulsion of a copolymer of styrene / n-butyl acrylate / acetoacetic acid monomer having a solid content of 45% (4), except that a styrene monomer was used instead of the methyl methacrylate monomer. (Iron content 43 ppm) was obtained. The evaluation results of the obtained aqueous emulsion are shown in Table 1.
The calculated glass transition temperature (Tg) of the polymer composed of this main polymerization monomer (styrene / n-butyl acrylate = 44.8 / 54.7 = 45.0 / 55.0 (weight ratio)) is respectively It was -2 degreeC when Tg of this homopolymer was -52 degreeC and +100 degreeC.

Example 5
Instead of PVA containing acetoacetyl group, PVA having 1,2-diol bond in the side chain (saponification degree 97.5 mol%, polymerization degree 300, content of 1,2-diol bond in the side chain 3 mol%, Except for using Nippon Synthetic Chemical Industry Co., Ltd., an aqueous emulsion of a copolymer of methyl methacrylate / n-butyl acrylate / acetoacetic acid monomer having a solid content of 45% (5) (Iron content 43 ppm) was obtained. The evaluation results of the obtained aqueous emulsion are shown in Table 1.
The calculated glass transition temperature (Tg) of the polymer composed of the main polymerization monomer was −1 ° C. as in Example 1.

Comparative Example 1
Except that 30% hydrogen peroxide aqueous solution was not added, the same procedure as in Example 1 was carried out (however, the amount of water charged was 405 g). The solid content of methyl methacrylate / n-butyl acrylate / acetoacetic acid monomer of 45% An aqueous emulsion (6) of the copolymer was obtained. The evaluation results of the obtained aqueous emulsion are shown in Table 1.
The calculated glass transition temperature (Tg) of the polymer composed of the main polymerization monomer was −1 ° C. as in Example 1. The graft ratio of the obtained aqueous emulsion was 78%.

Comparative Example 2
In a 1 L separable flask equipped with a stirrer, reflux condenser, dropping funnel, thermometer, 390 g of water, 23 g of acetoacetyl group-containing PVA as in Example 1, 0.7 g of acidic sodium sulfite, sodium acetate 1 as a pH adjuster .2 g was added and heated and stirred at 85 ° C. for 1 hour (stirring speed was 230 rpm) to dissolve the acetoacetyl group-containing PVA, then 14 g of 30% aqueous hydrogen peroxide was added and stirred at 85 ° C. for 60 minutes. Continued. Thereafter, the temperature was raised again to confirm that the acetoacetyl group-containing PVA aqueous solution was stabilized at 83 ° C., and a polymerization monomer (methyl methacrylate / n-butyl acrylate / acetoacetic acid monomer = 44.8 / 54.7 / 0.5) was added all at once, and after 5 minutes of sufficient stirring, 5.3 g of a 5% ammonium persulfate aqueous solution was added all at once to initiate initial polymerization. The initial polymerization was carried out for 45 minutes, and then 293 g of the remaining polymerization monomer was added dropwise at 82-83 ° C. over 3.5 hours. Further, 10.7 g of 5% ammonium persulfate aqueous solution was divided into 7 times every 30 minutes. Polymerization was carried out by adding. 1.8 g of 5% ammonium persulfate aqueous solution was added in two portions, and the latter polymerization was scheduled to be performed at 82 ° C. for 90 minutes. However, the viscosity of the system increased before the completion of the dropping polymerization, and the emulsion aggregated soon. The polymerization was stopped.
The calculated glass transition temperature (Tg) of the polymer composed of the main polymerization monomer was −1 ° C. as in Example 1.

Examples 1 to 5, which were heat-treated with hydrogen peroxide, did not thicken easily even at low temperatures such as 0 ° C. during storage, did not form a purine, and had a viscosity ratio (V ₀ / V ₂₃ ). It can be seen that Comparative Examples 1 and 2 were inferior in viscosity stability, whereas the viscosity stability was an aqueous emulsion having a viscosity of 20 or less.

  The aqueous emulsion of the present invention has a good viscosity stability even after emulsion polymerization, and has an excellent effect on the viscosity stability at a low temperature that does not easily thicken even at a low temperature such as 0 ° C. Furthermore, a re-emulsifiable resin powder obtained by spray-drying the aqueous emulsion has the same effect as a re-emulsified emulsion, and is used for civil engineering and building materials (such as mortar admixtures), paint applications, and adhesives. -Useful for adhesives, fiber processing, paper processing, inorganic binder applications, resin modification applications, soil immobilization applications, culture soil binder applications, and cosmetic applications. Among these, the aqueous emulsion of the present invention Is used for admixture of cement and mortar (cement primer, inorganic finish, mortar sealer and primer mortar curing agent), adhesive and Chakuzai applications, textile processing applications, paper processing applications, it is further very useful as redispersible powders for resin stock solution or the like.

Claims (9)

(Meth) acrylic acid ester monomer, styrene monomer and diene least one monomer is polymerized as a main component a polymer selected from the group consisting of monomers, active hydrogen An aqueous emulsion dispersed with a functional group-containing polyvinyl alcohol resin (A1) and / or a polyvinyl alcohol resin (A2) having a 1,2-diol bond in the side chain, the aqueous emulsion containing the polymer Is an aqueous emulsion characterized by being oxidized with 1 to 15% by weight of an oxidizing agent based on the solid content of the aqueous emulsion. The aqueous emulsion according to claim 1, wherein the oxidation treatment is performed at a temperature of 50 to 100 ° C. Functional group-containing polyvinyl alcohol-based resin having an active hydrogen (A1) is, according to claim 1 or 2 wherein the aqueous emulsion, characterized in der Rukoto saponification degree 95 mol% or more. Functional group-containing polyvinyl alcohol-based resin having an active hydrogen (A1) is a acetoacetyl group-containing polyvinyl alcohol-based resin, acetoacetylated degree 0.01-5 mol%, degree of polymerization of 20 to 1000 The aqueous emulsion according to claim 3. Polyvinyl alcohol resin having a 1,2-diol bond in a side chain (A2) is, according to claim 1 or 2 wherein the aqueous emulsion, characterized in der Rukoto saponification degree 85 mol% or more. The polyvinyl alcohol resin (A2) having a 1,2-diol bond in the side chain has a 1,2-diol bond amount in the side chain of 1 to 15 mol% and a polymerization degree of 50 to 2500. The aqueous emulsion according to claim 5. (Meth) acrylic acid ester monomer, styrene monomer and diene least one monomer is polymerized as a main component a polymer selected from the group consisting of monomers, active hydrogen A water-based emulsion dispersed with a functional group-containing polyvinyl alcohol resin (A1) and / or a polyvinyl alcohol resin (A2) having a 1,2-diol bond in the side chain, and having a solid content of 45% by weight. wherein the viscosity ratio of the viscosity after 16 hours standing at ° C. (V ₀₎ and the viscosity of 16 hours after standing at 23 ° C. in a solid content of 45 _{wt% (V 23) (V 0} / V 23) is 20 or less An aqueous emulsion. In the presence of a functional group-containing polyvinyl alcohol resin (A1) having active hydrogen and / or a polyvinyl alcohol resin (A2) having a 1,2-diol bond in the side chain , a (meth) acrylic acid ester monomer, A method for producing an aqueous emulsion comprising a polymer obtained by polymerizing at least one monomer selected from the group consisting of a styrene monomer and a diene monomer as a main component, the polymer A method for producing an aqueous emulsion, characterized by oxidizing an aqueous emulsion containing 1 to 15% by weight of an oxidizing agent with respect to the solid content of the aqueous emulsion. A re-emulsifiable resin powder obtained by removing water from the aqueous emulsion according to claim 1.