JP2006232927A - Vinyl acetate resin emulsion and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a vinyl acetate resin emulsion which has excellent low-temperature film-forming properties and excellent adhesive strength and is excellent in fluidity. <P>SOLUTION: The vinyl acetate resin emulsion is a vinyl acetate resin emulsion obtained by polymerizing a monomer component containing at least vinyl acetate, wherein the polymerization of the monomer component containing at least vinyl acetate is followed by the addition of a mixture of a liquid plasticizer and a powdery water-soluble polymeric compound. The liquid plasticizer is desirably a liquid plasticizer (e. g. , a fatty acid ester liquid plasticizer or an aromatic carboxylic acid ester liquid plasticizer other than a phthalic ester liquid plasticizer) other than a phthalic ester liquid plasticizer, and the powdery water-soluble polymeric compound is exemplified by a powdery polyvinyl alcohol polymer or a powdery polyvinylpyrrolidone polymer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vinyl acetate resin emulsion useful as an adhesive, a paint base, a coating agent, and the like, and a method for producing the vinyl acetate resin emulsion.

  Conventionally, vinyl acetate resin emulsions are widely used for adhesives, paint bases and coating agents for woodworking, paper processing, fiber processing and the like. However, since the minimum film-forming temperature is high as it is, in many cases, it is necessary to add film-forming aids such as volatile plasticizers and organic solvents. Phthalic acid esters (phthalic acid ester plasticizers) are used as the plasticizer, but there are indications that phthalic acid esters are undesirable for the environment due to the recent increase in environmental problems. Alternatives to high plasticizers are being considered.

  In addition, as various processing agents including a vinyl acetate resin emulsion or a vinyl acetate resin emulsion, for example, vinyl acetate is seed-polymerized into an ethylene vinyl acetate copolymer resin emulsion having an ethylene content of 15 to 35% by mass. There has been proposed a woodworking adhesive containing a vinyl acetate resin emulsion (see Patent Document 1). Further, in a method for producing a vinyl acetate resin emulsion by seed polymerization of vinyl acetate in an ethylene-vinyl acetate copolymer resin emulsion, a step of performing seed polymerization while adding vinyl acetate into the system, As a pre-process or post-process of the process, a polymerizable unsaturated monomer other than vinyl acetate is added to the system, or a polymerizable unsaturated monomer other than vinyl acetate is added to the vinyl acetate during the process. A method for producing a vinyl acetate resin emulsion including a step of independently adding it into the system has been proposed (see Patent Documents 2 and 3).

  Furthermore, as a method for producing a vinyl acetate resin emulsion obtained by seed polymerization of vinyl acetate, the copolymer in the ethylene-vinyl acetate copolymer emulsion is used as a seed in the presence of a protective colloid of polyvinyl alcohol. In the method for producing a vinyl acetate resin emulsion in which vinyl acetate monomer is added dropwise to perform seed polymerization, 3 to 15% by mass of vinyl acetate monomer to be polymerized and 15 to 30% by mass of a specified amount of polymerization initiator %, A core-shell type emulsion using a vinyl acetate monomer and an acrylic acid monomer using a polyvinyl alcohol resin as a protective colloid When performing polymerization, the vinyl acetate monomer is used to form the core Perform emulsion polymerization, followed has been proposed a method of producing vinyl acetate resin emulsion for performing emulsion polymerization of the shell portion with a mixture of vinyl acetate monomer and acrylic acid-based monomer (see Patent Document 5).

JP-A-11-92734 JP 2000-239307 A JP 2000-302809 A JP 2001-131206 A JP 2001-302709 A

  However, when emulsion polymerization of vinyl acetate monomer is performed in the presence of protective colloids, the resulting vinyl acetate resin emulsion has a structure due to hydrogen bonding between the formed emulsion particles and pseudo-aggregation between the emulsion particles. Shows viscosity. Therefore, even when the viscosity of the vinyl acetate resin emulsion is measured under the same temperature condition using a BH viscometer, the measured viscosity value varies greatly depending on the number of rotations of the rotor. The viscosity value measured at a low rotational speed is high, while the viscosity value measured at a high rotational speed is low.

  In other words, a vinyl acetate resin emulsion obtained by emulsion polymerization of a vinyl acetate monomer in the presence of a protective colloid has a high viscosity value in a stationary state (static viscosity) and a viscosity value in a stirred state. This phenomenon becomes more prominent in the vinyl acetate resin emulsion obtained by seed polymerization of the vinyl acetate monomer in the ethylene-vinyl acetate copolymer resin emulsion because the particle size becomes larger. It tends to appear. The greater the difference between the value of the viscosity in the stationary state and the value of the viscosity in the stirring state, the more fluidity of the vinyl acetate resin emulsion is lost. Therefore, for example, when the vinyl acetate resin emulsion is stored in a container having a narrow mouth (removal port), it is difficult to take out the vinyl acetate resin emulsion when the vinyl acetate resin emulsion is taken out of the container at the time of use. .

  Although it is possible to facilitate removal from a container with a narrow outlet by reducing the viscosity of the vinyl acetate resin emulsion, dripping of the adhesive occurs when applied to a vertical surface or the like. . For this reason, there is a need for a vinyl acetate resin-based emulsion with improved fluidity without reducing viscosity.

Accordingly, an object of the present invention is to provide a vinyl acetate resin emulsion having excellent low-temperature film formability and adhesive strength and excellent fluidity, and a method for producing the vinyl acetate resin emulsion. It is in.
Another object of the present invention is to provide a vinyl acetate resin emulsion not containing a phthalate ester plasticizer and a method for producing the vinyl acetate resin emulsion.

  As a result of intensive studies to solve the above problems, the present inventors have added a mixture of a liquid plasticizer and a specific polymer compound to a vinyl acetate resin emulsion obtained by polymerizing vinyl acetate. It has been found that the fluidity can be greatly improved without lowering the proportion of non-volatile content while maintaining the excellent characteristics of the vinyl acetate resin emulsion obtained by polymerizing vinyl. The present invention has been completed based on these findings.

  That is, the present invention is a vinyl acetate resin emulsion obtained by polymerizing a monomer component containing at least vinyl acetate, and after polymerizing the monomer component containing at least vinyl acetate, the liquid plasticizer and powder water-soluble Provided is a vinyl acetate resin emulsion characterized in that a mixture with a polymer compound is added.

  The vinyl acetate resin emulsion of the present invention is a vinyl acetate resin emulsion obtained by seed polymerization of a monomer component containing at least vinyl acetate in an emulsion containing a polymer of a polymerizable unsaturated monomer (X). Yes, after seed polymerization of a monomer component containing at least vinyl acetate in an emulsion containing a polymer of polymerizable unsaturated monomer (X), and then a mixture of a liquid plasticizer and a powdery water-soluble polymer compound Is preferably added.

  As the liquid plasticizer, a liquid plasticizer other than the phthalate ester liquid plasticizer can be preferably used. In particular, the fatty acid ester liquid plasticizer or the aromatic carboxylic acid other than the phthalate ester liquid plasticizer. Ester liquid plasticizers are preferred. The powdery water-soluble polymer compound is preferably a powdered polyvinyl alcohol polymer and / or a powdered polyvinylpyrrolidone polymer. Furthermore, the mixture of the liquid plasticizer and the powdered water-soluble polymer compound is a mixture of the powdered water-soluble polymer compound covered with the liquid plasticizer or dispersed in the liquid plasticizer. It can be used suitably.

  In the present invention, an ethylene-vinyl acetate copolymer resin or an acrylic resin can be used as the polymer of the polymerizable unsaturated monomer (X). In addition to vinyl acetate, a polymerizable unsaturated monomer (Y) other than vinyl acetate may be used as the monomer component for seed polymerization.

The present invention also provides a method for producing the vinyl acetate resin emulsion, which comprises the following steps (A) to (B).
Step (A): Step of polymerizing a monomer component containing at least vinyl acetate Step (B): Step of adding a mixture of a liquid plasticizer and a powdered water-soluble polymer compound after step (A)

  In the present specification, “acryl” and “methacryl” may be collectively referred to as “(meth) acryl”, “acryloyl” and “methacryloyl” may be collectively referred to as “(meth) acryloyl”, and the like.

  The vinyl acetate resin-based emulsion of the present invention has excellent low-temperature film-forming properties and adhesive strength, and is excellent in fluidity.

  The vinyl acetate resin emulsion of the present invention (sometimes referred to as “PVAc emulsion”) is obtained by polymerizing a monomer component containing at least vinyl acetate, and after polymerizing the monomer component containing at least vinyl acetate, This is a vinyl acetate resin emulsion to which a mixture of a plasticizer and a powdery water-soluble polymer compound is added. As described above, in the PVAc emulsion of the present invention, after the monomer component containing at least vinyl acetate is polymerized, the mixture of the liquid plasticizer and the powdery water-soluble polymer compound that becomes a non-volatile component is added. Thus, the fluidity of the PVAc emulsion can be increased without reducing the ratio of the nonvolatile content in the PVAc emulsion.

Therefore, the PVAc emulsion of the present invention has a small difference between the viscosity value measured at the high speed of the rotor and the viscosity value at the low speed in the viscosity measured using a BH type viscometer. The increase in viscosity in the installed state is suppressed. Specifically, the PVAc emulsion of the present invention has a rotor rotation speed of 2 r / min when viscosity measurement is performed at a temperature of 23 ° C. using a BH viscometer (manufactured by Tokimec Co., Ltd.). In the case where the viscosity is “η _{(2r / min)} ” and the viscosity when the rotation speed of the rotor is 10 r / min is “η _{(10r / min)} ”, the following equation (1) is obtained. The TI value can be less than 2.5 (preferably less than 2.0, more preferably 1.9 or less).
TI value = η _{(2r / min)} / η _{(10r / min)} (1)

  In addition, as a rotor used when a viscosity measurement is performed using a BH type viscometer, it can select suitably with the viscosity of a PVAc emulsion.

  In addition, since the PVAc emulsion has the above-described configuration, it has excellent low-temperature film formability and high adhesive strength. The low-temperature film-forming property is measured according to JIS K6804.

[Liquid plasticizer]
The liquid plasticizer is not particularly limited as long as it is a liquid (liquid) plasticizer at room temperature (20 to 25 ° C., particularly 23 ° C.), and is appropriately selected from known liquid plasticizers. be able to. A liquid plasticizer can be used individually or in combination of 2 or more types. As the liquid plasticizer, an oil-soluble, water-insoluble or poorly water-soluble liquid plasticizer can be suitably used from the viewpoint of controlling dispersibility of the powdered water-soluble polymer compound.

  As the liquid plasticizer, a liquid plasticizer other than the phthalate ester liquid plasticizer (sometimes referred to as “non-phthalic acid liquid plasticizer”) can be suitably used from the viewpoint of environmental problems and the like. The non-phthalic acid liquid plasticizer is not particularly limited as long as it is a liquid plasticizer other than the phthalate ester liquid plasticizer. For example, a fatty acid ester liquid plasticizer (aliphatic carboxylic acid ester liquid plasticizer), Aromatic carboxylic acid ester liquid plasticizers other than phthalate ester liquid plasticizers (sometimes referred to as “non-phthalic acid aromatic carboxylic acid ester liquid plasticizers”), phosphate ester liquid plasticizers, epoxies And liquid polyester plasticizers. In the present invention, a fatty acid ester liquid plasticizer or a non-phthalic acid aromatic carboxylic acid ester liquid plasticizer can be suitably used as the liquid plasticizer.

  As the fatty acid ester liquid plasticizer, an aliphatic polycarboxylic acid monohydric alcohol liquid plasticizer and an aliphatic monovalent carboxylic polyhydric alcohol liquid plasticizer can be suitably used. The aliphatic polycarboxylic acid monohydric alcohol liquid plasticizer may be an ester compound of an aliphatic polycarboxylic acid and a monohydric alcohol (monohydric hydroxy compound), and may be a free carboxylic acid group (carboxyl group). However, an ester compound in which all carboxylic acid groups of the aliphatic polyvalent carboxylic acid are reacted with a plurality of monohydric alcohols (particularly aliphatic monohydric alcohols) is preferable. Examples of such aliphatic polycarboxylic acid monohydric alcohol liquid plasticizer include diester compounds of aliphatic dicarboxylic acid and monohydric alcohol (for example, adipic acid diester liquid plasticizer, azelaic acid diester liquid plasticizer , Sebacic acid diester liquid plasticizer, succinic acid diester liquid plasticizer, and the like. Examples of the adipic acid diester include adipic acid dialkyl esters such as dibutyl adipate, diisobutyl adipate, di (2-ethylhexyl) adipate, diisodecyl adipate and the like, dibutyl diglycol adipate [di (diethylene glycol monobutyl ether) )] And the like. Examples of azelaic acid diester liquid plasticizers include azelaic acid di (2-ethylhexyl). Furthermore, examples of the sebacic acid diester liquid plasticizer include dibutyl sebacate and di (2-ethylhexyl) sebacate. Furthermore, examples of the succinic acid diester liquid plasticizer include diethyl succinate (diethyl succinate). In addition to these, tributyl citrate, methyl acetyl ricinoleate, and the like can also be used as the aliphatic polyvalent carboxylic acid monohydric liquid plasticizer.

  The aliphatic monovalent carboxylic acid polyhydric alcohol liquid plasticizer may be an ester compound of an aliphatic monovalent carboxylic acid and a polyhydric alcohol (polyhydric hydroxy compound). Although it may have, the ester type compound in which all the hydroxyl groups of the polyhydric alcohol (especially aliphatic polyhydric alcohol) reacted with the several aliphatic monohydric carboxylic acid is preferable. Examples of such aliphatic monovalent carboxylic acid polyhydric alcohol liquid plasticizers include diester compounds of polyhydric alcohol and aliphatic monovalent carboxylic acid (for example, isobutanoic acid polyhydric alcohol liquid plasticizer). Can be mentioned. Examples of the isobutanoic acid polyhydric alcohol liquid plasticizer include 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate. And diol (mono or di) isobutyrate.

  Non-phthalic acid-based aromatic carboxylic acid ester-type liquid plasticizers include aromatic polyvalent carboxylic acid monohydric alcohol-based liquid plasticizers other than phthalic acid esters [ie, aromatic polyvalent carboxylic acids other than phthalic acid and Ester compound with monohydric alcohol (monohydric hydroxy compound)], aromatic monovalent carboxylic acid polyhydric alcohol liquid plasticizer [ie polyhydric alcohol (polyhydric hydroxy compound), An ester compound with an aromatic monovalent carboxylic acid] can be preferably used. As such an aromatic monovalent carboxylic polyhydric alcohol liquid plasticizer, a benzoic polyhydric alcohol liquid plasticizer is suitable. Examples of the benzoic polyhydric alcohol liquid plasticizer include alkylene glycol dibenzoates such as dipropylene glycol dibenzoate, diethylene glycol dibenzoate, and propylene glycol dibenzoate.

[Powdered water-soluble polymer compound]
The powdery water-soluble polymer compound is not particularly limited as long as it is a powdered water-soluble polymer compound at room temperature (20 to 25 ° C., particularly 23 ° C.). It can be used by appropriately selecting from compounds. The powdery water-soluble polymer compound can be used alone or in combination of two or more.

  In addition, the powdery water-soluble polymer compound may be slightly water-soluble (soluble in water) at an appropriate temperature (for example, 1 to 99 ° C.). Accordingly, the solubility of the powdered water-soluble polymer compound in water is, for example, 1 at an appropriate temperature (for example, any temperature of 1 to 99 ° C., preferably any temperature of 40 to 90 ° C.). It may be not less than 10% by mass, preferably not less than 10% by mass (more preferably not less than 30% by mass, especially not less than 50% by mass). From the viewpoint of water-resistant adhesive strength and the like, the powdered water-soluble polymer compound has high solubility in warm water (for example, water heated to 40 to 90 ° C.). It is preferable. Of course, the time required for dissolution when the powdered water-soluble polymer compound is dissolved in water is not particularly limited.

  Specifically, examples of the powdery water-soluble polymer compound include powdered polyvinyl alcohol polymers, powdered polyvinylpyrrolidone polymers, powdered cellulose derivatives, powdered starch, powdered dextrin, and powdered oligosaccharides. , Powdered poly (meth) acrylamide, powdered polyvinyl alkyl ether polymer (polyvinyl methyl ether, etc.), powdered cyclodextrin, powdered gelatin, powdered agar, powdered pectin, powdered sodium alginate, powdered guar gum, powder Examples include gum arabic, powdered locust bean gum, powdered carrageenan, powdered casein, powdered tragacanth gum, powdered ferceleran, powdered collagen, powdered xanthan gum, powdered pullulan, powdered chitin, and powdered chitosan. In the present invention, the powdered water-soluble polymer compound is preferably a powdered polyvinyl alcohol polymer or a powdered polyvinyl pyrrolidone polymer, and in particular, a powdered polyvinyl alcohol polymer can be suitably used.

  The powdery polyvinyl alcohol-based polymer is not particularly limited as long as it is a powdery water-soluble polymer having at least a constituent unit of vinyl alcohol. Specifically, examples of the powdered polyvinyl alcohol polymer include various powdery modified polyvinyl alcohols [powdered (modified polyvinyl alcohol)] in addition to powdered polyvinyl alcohol. Examples of the powder-modified polyvinyl alcohol include powdered carboxyl group-modified polyvinyl alcohol (powdered carboxylic acid-modified polyvinyl alcohol), powdered alkyl group-modified polyvinyl alcohol, powdered thiol group-modified polyvinyl alcohol, and powdered acrylamide-modified polyvinyl alcohol. Is mentioned.

  In the powdered polyvinyl alcohol polymer such as the powdered polyvinyl alcohol, the bonding form of the vinyl alcohol unit as the monomer unit (monomer unit) is not particularly limited, and is a regularly bonded form (so-called “Head-to-tail connection” form, and forms that are not regularly connected (so-called “head-to-head connection”, “head-to-head connection” and “tail-to-tail connection” forms) Good. Therefore, the powdery polyvinyl alcohol polymer is a form in which a part of vinyl alcohol units as monomer units are bonded with carbon atoms having hydroxyl groups between adjacent vinyl alcohol units [so-called “head-head”. Having appropriate proportions of 1,2-dihydroxyethylene units formed by linking ”or“ tail-to-tail ”(usually referred to as“ head-to-head ”form) It may be. The powdered polyvinyl alcohol polymer may be either a partially saponified product or a completely saponified product. The saponification degree of the powdered polyvinyl alcohol-based polymer can be appropriately selected according to solubility in water, use, and the like.

  The powdery polyvinylpyrrolidone-based polymer is not particularly limited as long as it is a powdery water-soluble polymer having at least a constituent unit of vinylpyrrolidone. Specifically, examples of the powdered polyvinylpyrrolidone polymer include various powdery modified polyvinylpyrrolidones [powdered (modified products of polyvinylpyrrolidone)] in addition to powdered polyvinylpyrrolidone.

  Furthermore, the powdery cellulose derivative is not particularly limited as long as it is a powdery water-soluble polymer derived from cellulose. Specifically, examples of the powdery cellulose derivative include alkyl celluloses such as methyl cellulose and ethyl cellulose; hydroxyalkyl-alkyl celluloses such as hydroxypropyl methyl cellulose, hydroxyethyl methyl cellulose, and hydroxyethyl ethyl cellulose; hydroxyethyl cellulose, hydroxypropyl cellulose, and the like. Hydroxyalkyl celluloses; and cellulose ethers such as carboxyalkyl celluloses such as carboxymethyl cellulose or a salt thereof (such as sodium salt). The powdery cellulose derivative may be a cellulose ester.

  In addition, as long as the powdery water-soluble polymer compound has a powdery (solid powdery) shape, the average particle diameter is not particularly limited, and may be any size that can be regarded as powdery.

  Further, the degree of polymerization and the weight average molecular weight of the powdered water-soluble polymer compound can be appropriately selected according to the type of the polymer compound. For example, when the powdered water-soluble polymer compound is a powdered polyvinyl alcohol-based polymer, the degree of polymerization of the powdered polyvinyl alcohol-based polymer is appropriately selected from a range of, for example, 10 or more (for example, 10 to 5000). Can do. When the powdered water-soluble polymer compound is a powdered polyvinyl pyrrolidone polymer, the weight average molecular weight of the powdered polyvinyl pyrrolidone polymer is appropriately selected from the range of, for example, 5000 or more (for example, 5000 to 5000000). be able to.

[Monomer components subjected to polymerization]
In the present invention, a monomer component containing at least vinyl acetate is polymerized. The monomer component used in such polymerization is not particularly limited as long as it contains at least vinyl acetate. As the monomer component to be polymerized, only vinyl acetate may be used, and together with vinyl acetate, a polymerizable unsaturated monomer (Y) other than vinyl acetate (simply referred to as “polymerizable unsaturated monomer (Y)”. May be used).

  The polymerizable unsaturated monomer (Y) is not particularly limited. For example, (meth) acrylic acid esters (acrylic acid esters, methacrylic acid esters), vinyl esters, vinyl ethers, aromatic vinyl compounds , Unsaturated carboxylic acid amides, olefins, dienes, and unsaturated nitriles. The polymerizable unsaturated monomer (Y) can be used alone or in combination of two or more.

In the polymerizable unsaturated monomer (Y), as the (meth) acrylic acid esters, any conventionally known (meth) acrylic acid esters can be used. Typical examples include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, and s-butyl (meth) acrylate. , T-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, ( Such as isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate ( meth) acrylic acid alkyl esters [preferably (meth) acrylic acid C _1-18 alkyl ester More preferably exemplified include (meth) acrylic acid C _1-14 alkyl ester.

  Moreover, (meth) acrylic acid esters include hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate; methoxymethyl (meth) acrylate and (meth) acrylic acid. Alkoxyalkyl (meth) acrylates such as ethoxymethyl; reactive functional group-containing (meth) acrylates such as glycidyl (meth) acrylate can also be used.

As the vinyl esters, any conventionally known vinyl ester other than vinyl acetate can be used. As typical examples, for example, vinyl formate; vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl octylate, Veova 10 (trade name: Shell Japan Co., Ltd.) And vinyl esters of C _3-18 aliphatic carboxylic acids such as vinyl benzoate, and the like.

  Any conventionally known vinyl ethers can be used as the vinyl ethers. Typical examples include alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, iso-propyl vinyl ether, n-butyl vinyl ether, sec-butyl vinyl ether, tert-butyl vinyl ether, and tert-amyl vinyl ether. It is done.

  Examples of the aromatic vinyl compound include styrene, vinyl toluene, α-methyl styrene, N-vinyl pyrrolidone, vinyl pyridine and the like. Unsaturated carboxylic acid amides include (meth) acrylamides such as (meth) acrylamide, N-methylolacrylamide, N-methoxymethylacrylamide, and N-methoxybutylacrylamide. Examples of olefins include ethylene, propylene, butylene, isobutylene, and pentene. Examples of dienes include butadiene, isoprene, chloroprene and the like. Moreover, (meth) acrylonitrile etc. are mentioned as unsaturated nitriles.

  In the vinyl acetate resin emulsion (PVAc emulsion) of the present invention, a monomer component containing at least vinyl acetate (a monomer component containing vinyl acetate and, if necessary, a polymerizable unsaturated monomer (Y)) is polymerized. In this polymerization, the polymerization form is not particularly limited, and may be a solution polymerization form in which polymerization is performed in a solution, but an emulsion polymerization form in which polymerization is performed in an emulsion is preferable. A seed polymerization form in which seed polymerization is performed in an emulsion containing a polymer of a saturated monomer (X) (sometimes referred to as “seed emulsion (Z)”) is preferable. Therefore, a PVAc emulsion is obtained by polymerizing (emulsion polymerization) a monomer component containing at least vinyl acetate in the emulsion (in the presence of a protective colloid), and after polymerizing the monomer component containing at least vinyl acetate, In addition, a vinyl acetate resin emulsion to which a mixture of a liquid plasticizer (particularly a non-phthalic acid liquid plasticizer) and a powdery water-soluble polymer compound is added is preferable. In particular, in the seed emulsion (Z), at least It is obtained by seed polymerization of monomer component containing vinyl acetate, and after seed polymerization of monomer component containing at least vinyl acetate, liquid plasticizer (especially non-phthalic acid type liquid plasticizer) and powdery water-soluble polymer A vinyl acetate resin emulsion to which a mixture with a compound is added is preferred.

  In the case where a monomer component containing at least vinyl acetate is prepared by solution polymerization, a polymer obtained by solution polymerization of a monomer component containing at least vinyl acetate is emulsified using a protective colloid as necessary. A vinyl acetate resin emulsion can be prepared. Therefore, as a PVAc emulsion, after a polymer obtained by polymerizing a monomer component containing at least vinyl acetate (emulsion polymerization) in a solution is emulsified, a liquid plasticizer (especially a non-phthalic acid type liquid) is further obtained. A vinyl acetate resin emulsion to which a mixture of a plasticizer) and a powdery water-soluble polymer compound is added can be obtained.

[Emulsion containing polymer of polymerizable unsaturated monomer (X)]
When seed polymerization is used as the polymerization for obtaining the PVAc emulsion, at the time of seed polymerization of the monomer component containing at least vinyl acetate, as described above, the emulsion containing the polymer of the polymerizable unsaturated monomer (X) [Seed emulsion (Z)] can be used. Therefore, in this seed polymerization, the seed emulsion (Z) is used as the seed emulsion (that is, the emulsion particles in the seed emulsion (Z) are used as the seed particles, and the seed emulsion (Z) is used as the seed polymer. Polymers of polymerizable unsaturated monomers (X) are used).

  Examples of the polymerizable unsaturated monomer (X) include vinyl polymerizable monomers such as vinyl esters, (meth) acrylic esters and olefins (polymerizable monomers having an ethylenic double bond). 1 type (s) or 2 or more types of (mer) can be used.

As vinyl esters, for example, vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl octylate, Veova 10 (trade name) : _C1-18 aliphatic carboxylic acid vinyl esters such as Shell Japan; and vinyl esters of aromatic carboxylic acids such as vinyl benzoate. Examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, and (meth) acrylic. S-butyl acid, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) acryl Octyl acid, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, (meth) acrylic acid Examples include (meth) acrylic acid alkyl esters such as stearyl. Examples of olefins include ethylene, propylene, butylene, isobutylene, and pentene.

  As a typical example of the polymer of the polymerizable unsaturated monomer (X) (sometimes referred to as “polymer (X1)”), an ethylene-vinyl acetate copolymer (“ethylene-vinyl acetate copolymer”) is used. Olefin-vinyl acetate copolymer, vinyl acetate- (meth) acrylic acid ester copolymer, (meth) acrylic acid ester polymer (including copolymer), ethylene- Examples include (meth) acrylic acid ester-vinyl acetate copolymers. As the polymer (X1), an ethylene-vinyl acetate copolymer resin and a (meth) acrylic acid ester-based polymer are preferable, and an ethylene-vinyl acetate copolymer resin is particularly preferable. In addition, a polymer (X1) can be used individually or in combination of 2 or more types.

  In the polymer (X1), the ethylene-vinyl acetate copolymer resin is not particularly limited, but usually an ethylene-vinyl acetate copolymer resin having an ethylene content of about 5 to 60% by mass is used. Among them, as the ethylene-vinyl acetate copolymer resin, the ethylene-vinyl acetate copolymer resin having an ethylene content in the range of 15 to 35% by mass gives particularly low film forming temperature and also gives excellent adhesive strength. Therefore, it is preferable.

  In addition, vinyl acetate content in ethylene-vinyl acetate copolymer resin is about 40-95 mass% normally (preferably 65-85 mass%). The ethylene-vinyl acetate copolymer resin contains a crosslinkable monomer as a monomer component at a content of about 0 to 10% by mass.

  Accordingly, as the seed emulsion (Z), an emulsion containing an ethylene-vinyl acetate copolymer resin (sometimes referred to as “ethylene-vinyl acetate copolymer resin emulsion”) or a (meth) acrylic acid ester polymer is used. Emulsions can be suitably used, and ethylene-vinyl acetate copolymer resin emulsions are particularly preferred. Such ethylene-vinyl acetate copolymer resin emulsions are widely available on the market and can be easily obtained in the market. Commercially available ethylene-vinyl acetate copolymer resin emulsions can be used after adjusting the concentration by dilution with water or the like, if necessary.

  The seed emulsion (Z) may be an emulsion prepared by dispersing a polymer obtained in advance by polymerization (polymer used as a seed polymer) in water, or an emulsion produced by emulsion polymerization (used as a seed polymer). Emulsion containing polymer). The seed emulsion (Z) was prepared in the preceding stage in the multistage polymerization in which the step of preparing the seed emulsion (Z) by emulsion polymerization was performed in the previous stage, and the step of performing seed polymerization in the seed emulsion (Z) was performed in the subsequent stage. It may be an emulsion. The vinyl acetate resin emulsion of the present invention can also be produced by a series of polymerizations such as multistage polymerization.

[Method for producing vinyl acetate resin emulsion]
As described above, in the present invention, a monomer component containing at least vinyl acetate (that is, a monomer component containing only vinyl acetate or a monomer component containing a polymerizable unsaturated monomer (Y) together with vinyl acetate) is polymerized. Further, after this polymerization, a mixture of a liquid plasticizer (particularly a non-phthalic acid-based liquid plasticizer) and a powdery water-soluble polymer compound is further added. Therefore, the PVAc emulsion of the present invention can be produced by, for example, a method for producing a vinyl acetate resin emulsion comprising the following steps (A) to (B).
Step (A): Step of polymerizing a monomer component containing at least vinyl acetate Step (B): After step (A) [that is, after polymerizing a monomer component containing at least vinyl acetate], and further a liquid plasticizer and powder Adding a mixture with a water-soluble polymer compound

In the present invention, as described above, the polymerization form of the monomer component containing at least vinyl acetate is preferably a polymerization form in which polymerization is performed in an emulsion (in the presence of a protective colloid). It is preferable to produce by a method for producing a vinyl acetate resin emulsion comprising the following steps (A1) to (B1).
Step (A1): Step of polymerizing a monomer component containing at least vinyl acetate in an emulsion (in the presence of a protective colloid) Step (B1): After step (A1) [ie, at least vinyl acetate in the emulsion. After polymerizing the monomer component containing], and further adding a mixture of a liquid plasticizer and a powdery water-soluble polymer compound

In the present invention, the polymerization mode of the monomer component containing at least vinyl acetate is particularly preferably a seed polymerization mode in which seed polymerization is performed in the seed emulsion (Z). Therefore, the PVAc emulsion of the present invention is particularly preferably produced by a method for producing a vinyl acetate resin emulsion comprising the following steps (A2) to (B2).
Step (A2): Step of seed polymerization of monomer component containing at least vinyl acetate in seed emulsion (Z) Step (B2): After step (A2) [ie, at least vinyl acetate in seed emulsion (Z) After the seed polymerization of the monomer component containing], and further, a step of adding a mixture of the liquid plasticizer and the powdered water-soluble polymer compound

[Step (A)]
In the step (A), a monomer component containing at least vinyl acetate is polymerized. The step (A) includes a step (A1) of polymerizing in emulsion (emulsion polymerization) and a step of seed polymerization (A2) in the emulsion (Z). In such polymerization, as the monomer component to be subjected to polymerization, as described above, a monomer component containing only vinyl acetate or a monomer component containing a polymerizable unsaturated monomer (Y) together with vinyl acetate is used. The amount of the polymerizable unsaturated monomer (Y) used can be selected within a wide range depending on the desired properties of the emulsion. The amount of the polymerizable unsaturated monomer (Y) used is, for example, 0 to 100 parts by mass (preferably 0.05 to 60 parts by mass, more preferably 0.05 to 40 parts by mass with respect to 100 parts by mass of vinyl acetate. Part) grade.

  The method for adding monomer components such as vinyl acetate and polymerizable unsaturated monomer (Y) to the system is not particularly limited, and may be any of the batch addition method, continuous addition method, and intermittent addition method. May be. In addition, as a method for adding vinyl acetate into the system, a continuous addition method or an intermittent addition method is preferable from the viewpoint of easy control of the reaction. On the other hand, when the polymerizable unsaturated monomer (Y) is added to the system, it may be added to the system as a mixture mixed with vinyl acetate (sometimes referred to as “mixed monomer”). These may be added to the system separately from vinyl acetate, and may also be added to the system by a combination of these methods. When the polymerizable unsaturated monomer (Y) is added to the system separately from the vinyl acetate, the method for adding the polymerizable unsaturated monomer (Y) is within a range in which the reaction can be controlled. Thus, it is preferable to add as short as possible as in the batch addition method.

  In addition, when polymerizing in an emulsion (particularly in the emulsion (Z)), monomer components such as vinyl acetate and a polymerizable unsaturated monomer (Y) may be separately added to the system. In any case, such as when it is added to the system in the form of a mixed monomer, it may be mixed with a protective colloid aqueous solution such as polyvinyl alcohol and added to the system in an emulsified state. Specific examples of the protective colloid are as shown below.

  In the step (A), during the polymerization (particularly seed polymerization), the vinyl acetate and the polymerizable unsaturated monomer (Y) can be polymerized simultaneously or separately. That is, in the step (A), the polymerizable unsaturated monomer (Y) may be added to the system during the polymerization of vinyl acetate, and is added to the system before and after the polymerization of vinyl acetate. Also good. The polymerizable unsaturated monomer (Y) may be added to the system before or after adding vinyl acetate to the system when polymerizing vinyl acetate. Therefore, the polymerizable unsaturated monomer (Y) may be added to the system as a mixture mixed with vinyl acetate, may be added to the system separately from vinyl acetate, or a combination thereof. You may add in a system in a form.

  In the step (A), an emulsion is used in the step (A1). In particular, in the step (A2), an emulsion (Z) (a polymer of a polymerizable unsaturated monomer (X) is included as the emulsion. Emulsion) is used. As such an emulsion, an emulsion prepared using an emulsifier or the like can be used as necessary. The emulsifier is not particularly limited and can be appropriately selected from known emulsifiers, and polyvinyl alcohol is preferred. Examples of the polyvinyl alcohol as the emulsifier include general polyvinyl alcohol and modified polyvinyl alcohol such as acetoacetylated polyvinyl alcohol. The polyvinyl alcohol may be either a partially saponified product or a completely saponified product, and two or more kinds of polyvinyl alcohols having different molecular weights or saponification degrees may be used in combination.

  In the seed polymerization in step (A2), the amount of seed emulsion (Z) used is not particularly limited. As the seed emulsion (Z), for example, the amount (solid content) of the seed polymer (for example, ethylene-vinyl acetate copolymer resin) in the seed emulsion (Z) is the total amount of the vinyl acetate resin emulsion obtained by seed polymerization. The content in the resin component (total solid content) is desirably used in a proportion of about 3 to 40% by mass (preferably 5 to 35% by mass, more preferably 10 to 30% by mass).

  In the monomer component to be subjected to seed polymerization, the amount of vinyl acetate used is, for example, 10 to 90% by mass (preferably 15%) with respect to the total resin (total solid content) of the vinyl acetate resin emulsion obtained by seed polymerization. ˜85 mass%, more preferably 40-80 mass%).

  In step (A) [particularly step (A2)], vinyl acetate is added to the system and polymerization is performed (sometimes referred to as “step (Aa)”), polymerizable unsaturated monomer. When the body (Y) is added to the system separately from the vinyl acetate (sometimes referred to as “process (Ab)”), the cured product or film of the vinyl acetate resin emulsion is provided. The low-temperature adhesive strength can be greatly improved. Accordingly, as the step (A), the step (Aa) in which polymerization is carried out while adding vinyl acetate into the system, and the polymerizable unsaturated monomer (Y) are separated from the vinyl acetate independently. It is preferable that it is comprised by the process (Ab) added inside. In addition, since seed polymerization is performed in the step (A2), the step (A2) includes a step (A2-a) of performing seed polymerization while adding vinyl acetate into the system, and a polymerizable unsaturated monomer ( The step (A2-b) of adding Y) to the system independently of the vinyl acetate can be constituted.

  The step (Aa) is not particularly limited as long as it is a step in which vinyl acetate is added into the system and polymerization [seed polymerization in the case of step (A2-a)] is performed. For example, vinyl acetate is added. It may be a step of performing polymerization while being added to the system, or may be a step of performing polymerization after adding vinyl acetate to the system. Furthermore, a part of vinyl acetate is added to the system. After the addition, polymerization is performed, and then, after that, the remainder of the vinyl acetate is added to the system, and the process may be performed in any form such as a process of performing polymerization.

  In the step (Ab), the step (Aa) is performed before adding vinyl acetate into the system [the previous step of the step (Aa)], in the step (Aa). Any of the steps performed after adding vinyl acetate into the system [the post-step of the step (Aa)] or the steps performed during the step (Aa) [the step performed during the step (Aa)] This step may be used. As described above, the step (Ab) is provided as a step before the step (Aa) or a step after the step (Aa), or the step (Ab) is performed during the step (Aa). The above advantageous effects can be obtained.

  In addition, performing a process (Ab) as a pre-process of a process (Aa) means adding vinyl acetate and polymerizing [in the case of a process (A2-a), seed polymerization] as mentioned above. In addition, it means that a polymerizable unsaturated monomer (Y) is added to the system. In this case, addition of the polymerizable unsaturated monomer (Y) can be performed in any state in the presence or absence of the polymerization initiator. That is, the polymerization of the polymerizable unsaturated monomer (Y) may be started before the start of polymerization of vinyl acetate, or may be started simultaneously with the start of the polymerization of vinyl acetate. In addition, after the polymerization of the polymerizable unsaturated monomer (Y) is completed, the polymer by the polymerizable unsaturated monomer (Y) (in the case where there is only one type of polymerizable unsaturated monomer (Y)) In the case where two or more homopolymers and polymerizable unsaturated monomers (Y) are used, the copolymer))] is formed, and then the process proceeds to step (Aa). Two-stage polymerization may be performed.

  Moreover, performing a process (Ab) as a post process of a process (Aa) is adding a polymerizable unsaturated monomer (Y) in a system after completion | finish of addition of vinyl acetate as mentioned above. It means that the polymerizable unsaturated monomer (Y) is subjected to polymerization. In this case, the addition of the polymerizable unsaturated monomer (Y) may be performed after completion of the polymerization of vinyl acetate [in the case of step (A2-a), seed polymerization].

  Furthermore, when the step (Ab) is performed during the step (Aa), as described above, vinyl acetate is added to perform polymerization [in the case of the step (A2-a), seed polymerization]. In the middle, the polymerizable unsaturated monomer (Y) is added to the system separately from the vinyl acetate and is subjected to polymerization. In this case, the polymerizable unsaturated monomer (Y) is added at any stage in the process (Aa) (vinyl acetate addition stage, vinyl acetate addition and seed polymerization stage, vinyl acetate seed). Polymerization stage etc.) may be used, but the first stage of the process (Aa) (namely, the vinyl acetate addition stage) is preferred.

  In the step (A) [especially step (A2) or step (A2-a)], the polymerization temperature in the polymerization [in the case of step (A2) or step (A2-a), seed polymerization] is a polymerization initiator. For example, it is about 60 to 90 ° C. (preferably 70 to 85 ° C.), but is not limited thereto.

  In addition, in the step (Ab), the temperature at which the polymerizable unsaturated monomer (Y) is added to the system separately from the vinyl acetate is the polymerizable unsaturated monomer (Y) addition step. Is the same as the temperature in the step (Aa) (polymerization temperature in the polymerization), but the step of adding the polymerizable unsaturated monomer (Y) is performed. When the polymerization of the polymerizable unsaturated monomer (Y) is started at the time of the step (Aa), it is provided as a previous step of the step (Aa). The temperature at the time of addition of Y) is not particularly limited.

When the polymerizable unsaturated monomer (Y) is added to the system separately from vinyl acetate, the polymerizable unsaturated monomer (Y) is exemplified by the polymerizable unsaturated monomers specifically exemplified above. Although a saturated monomer (Y) can be used, among these, it is preferable to use at least one selected from acrylic acid esters, methacrylic acid esters, vinyl esters and vinyl ethers. As the polymerizable unsaturated monomer (Y), in particular, (meth) acrylic acid alkyl ester [for example, (meth) acrylic acid C _1-18 alkyl ester, particularly (meth) acrylic acid C _1-14 alkyl ester] , Vinyl esters of C _3-14 aliphatic carboxylic acids are preferred because they have the least decrease in low-temperature adhesive strength during low-temperature curing. In addition to its low-temperature adhesive strength, from the standpoint of maintaining excellent low-temperature film-forming performance (low-temperature film-forming performance), the polymerizable unsaturated monomer (Y) is an acrylic acid C _3-12 alkyl ester. Further, methacrylic acid C _2-8 alkyl ester is more preferable.

  When the polymerizable unsaturated monomer (Y) is added to the system separately from the vinyl acetate, the amount of the polymerizable unsaturated monomer (Y) added separately depends on the adhesiveness of the PVAc emulsion, etc. Although it can select suitably in the range which does not impair the performance of this, generally it is the range of about 0.05-10 mass parts with respect to 100 mass parts of vinyl acetate. If the amount used is less than 0.05 parts by mass, the adhesive strength during low-temperature curing (low-temperature adhesive strength) tends to decrease, and if it exceeds 10 parts by mass, the normal adhesive strength tends to decrease. Among the ranges of the use amount of the polymerizable unsaturated monomer (Y), the range in which the adhesive strength is excellent and the decrease in the low temperature adhesive strength at the time of low temperature curing is the smallest is 100 parts by mass of vinyl acetate. The range is 0.1 to 7 parts by mass (particularly preferably 0.5 to 4 parts by mass).

  In step (A2) or step (A2-a), the monomer component to be subjected to seed polymerization is a monomer (monomer component) having a composition (kind) different from that of the monomer constituting the seed polymer, or the composition is the same. However, it is often a monomer (monomer component) having a different composition ratio.

  In the polymerization in the step (A) [particularly, seed polymerization in the step (A2)], a protective colloid may be used. The protective colloid is used by being premixed in an emulsion when polymerizing monomer components such as vinyl acetate and polymerizable unsaturated monomer (Y) [for example, seed emulsion (Z) when performing seed polymerization]. The monomer component (acetic acid added to the emulsion [for example, seed emulsion (Z) for seed polymerization, etc.] when polymerizing monomer components such as vinyl acetate and polymerizable unsaturated monomer (Y) may be used. Vinyl and a polymerizable unsaturated monomer (Y) etc.) may be mixed and used. Such a protective colloid is not particularly limited, and a protective colloid generally used for producing a vinyl acetate resin emulsion, for example, polyvinyl alcohol (PVA) or other water-soluble polymer is preferably used. The The polyvinyl alcohol may be, for example, modified polyvinyl alcohol such as acetoacetylated polyvinyl alcohol, in addition to general polyvinyl alcohol. The polyvinyl alcohol may be either a partially saponified product or a completely saponified product, and two or more kinds of polyvinyl alcohols having different molecular weights or saponification degrees may be used in combination. Thus, when polyvinyl alcohol as a protective colloid is present in the polymerization system, the polyvinyl alcohol has an effective function as an emulsifier in the polymerization, and the coating workability when a PVAc emulsion is used as an adhesive is improved. To do.

  The amount of the protective colloid can be appropriately selected within a range that does not impair the polymerizability at the time of polymerization or the adhesiveness when the PVAc emulsion is used as an adhesive, but generally, the total resin of the resulting vinyl acetate resin emulsion ( The total solid content is, for example, about 2 to 40% by mass (preferably 5 to 30% by mass, more preferably 8 to 25% by mass).

  In polymerization such as seed polymerization, a polymerization initiator (polymerization catalyst) can be used. The polymerization initiator is not particularly limited, and is a known or conventional polymerization initiator, for example, organic peroxides such as hydrogen peroxide and benzoyl peroxide, ammonium persulfate, potassium persulfate, sodium persulfate, azobisisobutyrate. Ronitrile and the like can be used. These polymerization initiators may be used as a redox polymerization initiator in combination with a reducing agent such as tartaric acid, sodium bisulfite, and ascorbic acid. The amount of the polymerization initiator used is, for example, 0. 100 parts by mass with respect to 100 parts by mass of the total amount of monomer components to be polymerized (total amount of vinyl acetate and polymerizable unsaturated monomer (Y) used as necessary). It is about 05-2 mass parts. Moreover, the usage-amount of the reducing agent at the time of using a redox type polymerization initiator can be suitably set according to the kind etc. of the said polymerization initiator.

  In polymerization such as seed polymerization, other additives (for example, a surfactant, a pH adjuster, etc.) and a chain transfer agent may be added as long as the polymerizability and performance as an adhesive are not impaired. .

  As a polymerization method, a known polymerization method can be used, and examples thereof include, but are not limited to, a monomer sequential addition method, a batch charging method, and a two-stage polymerization method. The polymerization apparatus is not particularly limited, and an atmospheric emulsion polymerization apparatus used in the industry can be used.

[Step (B)]
In step (B), after step (A) [that is, after polymerizing a monomer component containing at least vinyl acetate], the obtained vinyl acetate resin emulsion is further mixed with a liquid plasticizer and a powdery water-soluble polymer. A vinyl acetate resin emulsion (PVAc emulsion) to which a mixture of a liquid plasticizer and a powdery water-soluble polymer compound is added is prepared by adding a mixture with the compound. In addition, in the step (B), after the step (A1), after adding the mixture of the liquid plasticizer and the powdered water-soluble polymer compound (B1) or after the step (A2), the liquid plasticizer and A step (B2) of adding a mixture with the powdery water-soluble polymer compound is included.

  A mixture of a liquid plasticizer and a powdery water-soluble polymer compound (sometimes referred to as “polymer plasticizer mixture”) is a mixture of a liquid plasticizer and a powdered water-soluble polymer compound. Although not particularly limited, a mixture in which the powdered water-soluble polymer compound is covered with a liquid plasticizer or a mixture in which the powdered water-soluble polymer compound is dispersed in the liquid plasticizer is preferably used. be able to. Therefore, the polymer plasticizer mixture has a form in which the powdered water-soluble polymer compound is surrounded by the liquid plasticizer by being covered with the liquid plasticizer or being dispersed in the liquid plasticizer. It is preferable. When the polymer plasticizer mixture has such a form, when the powdered water-soluble polymer compound is poured into water, the surface absorbs moisture and becomes gelled (this tendency is caused by the water temperature Even if it has a high solubility in water so that it becomes insoluble (so-called “Mamako”), it becomes more prominent as it becomes higher. Since the powdery water-soluble polymer compound can be suppressed or prevented from abruptly coming into contact with a large amount of moisture, the powdered water-soluble polymer compound can be easily dissolved.

  The addition amount or use amount (solid content) of the polymer plasticizer mixture is not particularly limited. For example, the ratio of the solid content in the total amount of the vinyl acetate resin emulsion after the addition of the polymer plasticizer mixture is 20 to 20%. The ratio may be 80% by mass (preferably 30 to 65% by mass, more preferably 35 to 50% by mass). That is, it is important to add the polymer plasticizer mixture in such a ratio that the total amount of solid content (nonvolatile content) contained in the PVac emulsion is, for example, 20 to 80% by mass.

  Further, the addition amount or use amount (solid content) of the polymer plasticizer mixture is, for example, 10 with respect to the total amount of vinyl acetate resin emulsion (including the solid content and water) after the addition of the polymer plasticizer mixture. It can select from the range of about -120 mass% (preferably 15-90 mass%, More preferably, 15-60 mass%).

  In the polymer plasticizer mixture, the ratio between the liquid plasticizer and the powdered water-soluble polymer compound is not particularly limited, and for example, the liquid plasticizer / powdered water-soluble polymer compound (mass ratio) = 100. / 1 to 2/5 (preferably 25/1 to 3/5, more preferably 10/1 to 4/5).

  The method of adding the polymer plasticizer mixture to the vinyl acetate resin emulsion after polymerization is not particularly limited, and may be any addition method of batch addition method, continuous addition method, intermittent addition method, A batch addition method (particularly, a batch addition method with stirring) is preferred. The temperature at which the polymer plasticizer mixture is added to the vinyl acetate resin emulsion after polymerization is not particularly limited, and may be, for example, the temperature at the time of polymerization. Therefore, when the polymer plasticizer mixture is added, it is not necessary to adjust the temperature in the system after the completion of the polymerization. Therefore, after the polymerization is completed, the polymer plasticizer mixture is added to the system at a high temperature. PVac emulsions can be prepared easily and with excellent productivity. Of course, the polymer plasticizer mixture may be added to the system after adjusting the temperature in the system after polymerization to a predetermined temperature.

  In step (A), a monomer component containing at least vinyl acetate is added to the system to perform polymerization such as seed polymerization. After completing the addition of all the monomer components and performing polymerization, the reaction is completed. In order to achieve this, usually, the aging is performed by further continuing stirring (that is, the aging step is performed after the step (A)). Thus, when the aging step for completing the polymerization reaction is performed after the step (A), the step (B) may be performed after the aging step, but before the aging step or during the aging step. It is preferable to carry out (especially before the aging step). By carrying out step (B) before or during the aging process (that is, after adding the polymer plasticizer mixture to the system, aging to complete the polymerization reaction or polymerization reaction) The polymer plasticizer mixture may be added to the system while aging to complete the polymerization), and the polymer plasticizer mixture may be dissolved while aging to complete the polymerization reaction. The productivity of the PVAc emulsion can be further increased. Therefore, in the present invention, the step (B) is any of the step (A) and the aging step, the aging step after the step (A), the step (A), and the aging step. This can be done in one or more stages.

  Therefore, in this invention, after performing a process (A), you may prepare the vinyl acetate resin-type emulsion (PVac emulsion) of this invention by performing a process (B) succeedingly, and a process (A) previously The PVac emulsion may be prepared by performing the step (B) using the vinyl acetate resin emulsion obtained by performing the above steps. That is, in the PVac emulsion of the present invention, step (A) to step (B) may be performed as a series of steps, and step (A) and step (B) are performed as separate steps (discontinuous steps). May be.

Further, the PVac emulsion of the present invention [particularly, PVac emulsion prepared by seed polymerization using seed emulsion (Z)] can exhibit excellent low-temperature film-forming properties and high adhesive strength. Even at times, excellent low-temperature adhesive strength can be exhibited, and a significant decrease in adhesive strength during low-temperature curing can be prevented. For example, the retention value represented by the following formula can usually be 60% or higher, and can reach 70% or higher, or 80% or higher depending on the manufacturing conditions.
Retention rate (%) = [low temperature (5 ° C.) adhesive strength (N / mm ² ) / normal adhesive strength (N / mm ² )] × 100

  In addition, the said normal state adhesive strength shows the adhesive strength when an emulsion is used as an adhesive for woodworking, and is the value of the compression shear adhesive strength measured based on JIS K 6852. The low temperature (5 ° C.) adhesive strength is the adhesive strength when the emulsion is used as an adhesive for woodworking. The emulsion and the test piece are stored in an atmosphere at 5 ° C. for 1 day, and then at the same temperature. It is the value of the compressive shear bond strength measured according to JIS K 6852, except that it is bonded, cured and measured at the same temperature.

The normal state adhesive strength of the PVac emulsion of the present invention is, for example, 10 N / mm ² or more (for example, 10 to 30 N / mm ² ), preferably 15 N / mm ² or more (for example, 15 to 30 N / mm ² ).

  Moreover, the PVAc emulsion of the present invention [particularly, the PVac emulsion prepared by seed polymerization using the seed emulsion (Z)] has a low minimum film formation temperature, and the adherend is subjected to a low temperature (for example, 5 ° C. or less). The film formability (low temperature film formability) when applied and dried to form a film is excellent, and a transparent cured product or film can be formed even if the film is formed at a low temperature. As described above, the PVAc emulsion of the present invention has a low minimum film formation temperature (for example, 0 ° C. or lower), and can form a cured product or film exhibiting good transparency even at low temperatures. it can.

  Furthermore, the PVAc emulsion of the present invention [in particular, the PVac emulsion prepared by seed polymerization using the seed emulsion (Z)] can exhibit good water resistance, and can be cured even when held in water. Alternatively, a significant decrease in the adhesive strength of the film can be prevented. Therefore, the cured product or film by the PVAc emulsion has good adhesive strength when held in water (water-resistant adhesive strength). For example, even if the cured product or film is wet, It does not peel off easily.

  The PVAc emulsion of the present invention can form a cured product or film having good transparency, and can form a cured product or film having good water resistance. It is suitable as an active ingredient of various treatment agents such as coating agents.

  In addition, the PVAc emulsion of the present invention has excellent fluidity and suppresses an increase in the viscosity in a stationary state, so that even if it is stored in a container having a narrow outlet opening, it can be easily stored. It is possible to take it out. Therefore, PVAc emulsions are particularly suitable as various treatment agents (such as aqueous adhesives) stored in containers having a small capacity [for example, containers of 500 ml or less (preferably 30 to 300 ml, more preferably 50 to 200 ml)]. Can be used.

  The PVAc emulsion of the present invention can be used as it is as various treatment agents (for example, water-based adhesives, water-based paints, water-based coating agents, etc.), but if necessary, other polymer emulsions (for example, other acetic acid) It can be used as various treatment agents in a state of being mixed with a vinyl resin emulsion, an ethylene-vinyl acetate resin emulsion, an acrylic resin emulsion or the like.

  Further, in the PVAc emulsion of the present invention, water-soluble polymers such as cellulose derivatives are blended as thickeners, fillers, solvents, pigments, dyes, preservatives, antifoaming agents, suspending agents, fluidity improving agents. An agent, a rust inhibitor, a wetting agent, or the like may be added.

  The PVAc emulsion of the present invention is an adhesive that can be reassured not only for industrial use but also for school children and medical use as an aqueous adhesive. As described above, the PVAc emulsion of the present invention can be used for various purposes such as a paint base and a coating agent in addition to an adhesive.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited by these Examples.

Example 1
In a reaction vessel equipped with a stirrer, a reflux condenser, a dropping tank and a thermometer, 606 parts by mass of water was added, and with stirring, the product name “Kuraray Poval 217” [manufactured by Kuraray Co., Ltd., polyvinyl alcohol; (Sometimes referred to as “(1)”): 25 parts by mass, trade name “Kuraray Poval 117” [manufactured by Kuraray Co., Ltd., polyvinyl alcohol; sometimes referred to as “PVA (2)”]: 25 parts by mass, and tartaric acid : 1 part by mass was added and dissolved, and kept at 80 ° C. After polyvinyl alcohol [PVA (1) and PVA (2)] is completely dissolved, a catalyst (35% by mass hydrogen peroxide solution: an aqueous solution in which 1 part by mass is dissolved in 20 parts by mass of water) and a vinyl acetate monomer : 240 parts by mass were continuously dropped from separate dropping tanks over 2 hours. After completion of dropping, diisobutyl adipate as a liquid plasticizer [may be referred to as “liquid plasticizer (1)”]: 30 parts by mass, and a trade name “Kuraray Poval 217” as a powdered water-soluble polymer compound [stock] Made by Kuraray Co., Ltd., polyvinyl alcohol; sometimes referred to as “powder polymer (1)”]: A mixture with 30 parts by mass was added, and the mixture was further stirred for 1.5 hours while maintaining a temperature of 80 ° C. or higher. Then, it cooled to room temperature and obtained the vinyl acetate resin-type emulsion. The solid content of this vinyl acetate resin emulsion was 38% by mass.

(Example 2)
As a mixture of a liquid plasticizer and a powdered water-soluble polymer compound, 30 parts by mass of a liquid plasticizer (1) (diisobutyl adipate) as a liquid plasticizer and a trade name “Kuraray” as a powdered water-soluble polymer compound POVAL RS1717 ”[manufactured by Kuraray Co., Ltd., polyvinyl alcohol; sometimes referred to as“ powdered polymer (2) ”]: vinyl acetate in the same manner as in Example 1 except that a mixture with 30 parts by mass was used. A resin emulsion was obtained. The solid content of this vinyl acetate resin emulsion was 38% by mass.

(Example 3)
The amount of vinyl acetate monomer dropped to 240 parts by mass instead of 240 parts by mass, and as a mixture of a liquid plasticizer and a powdered water-soluble polymer compound, a liquid plasticizer (1) (diisobutyl adipate as a liquid plasticizer ): 30 parts by mass and a powdery polymer (1) (trade name “Kuraray Poval 217” manufactured by Kuraray Co., Ltd.) as a powdered water-soluble polymer compound: Except that a mixture of 20 parts by mass was used. In the same manner as in Example 1, a vinyl acetate resin emulsion was obtained. The solid content of this vinyl acetate resin emulsion was 38% by mass.

Example 4
The amount of vinyl acetate monomer dropped to 240 parts by mass instead of 240 parts by mass, and as a mixture of a liquid plasticizer and a powdered water-soluble polymer compound, a liquid plasticizer (1) (diisobutyl adipate as a liquid plasticizer ): 30 parts by mass and powdered polymer (1) (trade name “Kuraray Poval 217” manufactured by Kuraray Co., Ltd.) as a powdered water-soluble polymer compound: Except for using 10 parts by mass In the same manner as in Example 1, a vinyl acetate resin emulsion was obtained. The solid content of this vinyl acetate resin emulsion was 38% by mass.

(Example 5)
The amount of vinyl acetate monomer dropped to 240 parts by mass instead of 240 parts by mass, and as a mixture of a liquid plasticizer and a powdered water-soluble polymer compound, a liquid plasticizer (1) (diisobutyl adipate as a liquid plasticizer ): 30 parts by mass and trade name “ARUFON UP-1000” [manufactured by Toa Gosei Co., Ltd .; solid content: 100% by mass; acrylic polymer; sometimes referred to as “liquid polymer (1)” ]: 30 parts by weight of the mixture and powdered polymer (1) (trade name “Kuraray Poval 217” manufactured by Kuraray Co., Ltd.) as the powdered water-soluble polymer compound: except that 30 parts by weight of the mixture was used. In the same manner as in Example 1, a vinyl acetate resin emulsion was obtained. The solid content of this vinyl acetate resin emulsion was 38% by mass.

(Example 6)
The amount of vinyl acetate monomer added is 270 parts by mass instead of 240 parts by mass, and as a mixture of a liquid plasticizer and a powdery water-soluble polymer compound, the trade name “CS-12” [Chisso] 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate manufactured by Co., Ltd .; may be referred to as “liquid plasticizer (2)”]: 30 parts by mass, powdered water-soluble polymer compound As a powdered polymer (1) (trade name “Kuraray Poval 217” manufactured by Kuraray Co., Ltd.): A vinyl acetate resin emulsion was obtained in the same manner as in Example 1 except that a mixture with 30 parts by mass was used. It was. The solid content of this vinyl acetate resin emulsion was 38% by mass.

(Example 7)
The amount of vinyl acetate monomer dropped to 270 parts by mass instead of 240 parts by mass, and as a mixture of a liquid plasticizer and a powdered water-soluble polymer compound, the trade name “Benzoflex 9-88” as a liquid plasticizer [Versicol Chemical Co., Dipropylene glycol dibenzoate; may be referred to as “liquid plasticizer (3)”]: 30 parts by mass and powdered polymer (1) as a water-soluble powdery polymer Name “Kuraray Poval 217” manufactured by Kuraray Co., Ltd.): A vinyl acetate resin emulsion was obtained in the same manner as in Example 1 except that a mixture with 30 parts by mass was used. The solid content of this vinyl acetate resin emulsion was 38% by mass.

(Example 8)
In a reaction vessel equipped with a stirrer, a reflux condenser, a dropping tank and a thermometer, 550 parts by mass of water is added, and under stirring, PVA (1) (trade name “Kuraray Poval 217”, manufactured by Kuraray Co., Ltd.) : 36 parts by mass, PVA (2) (trade name “Kuraray Poval 117”, manufactured by Kuraray Co., Ltd.): 11 parts by mass and tartaric acid: 1 part by mass were dissolved and kept at 80 ° C. After polyvinyl alcohol [PVA (1) and PVA (2)] is completely dissolved, a catalyst (35% by mass hydrogen peroxide solution: an aqueous solution in which 1 part by mass is dissolved in 20 parts by mass of water) and a vinyl acetate monomer : 326 parts by mass were continuously added dropwise from separate dropping tanks over 2 hours. After completion of dropping, liquid plasticizer (1) as liquid plasticizer (diisobutyl adipate): 30 parts by mass and powdered polymer (1) as powdered water-soluble polymer compound (trade name “Kuraray Poval 217”, stock (Manufactured by Kuraray Co., Ltd.): A mixture with 20 parts by mass was added, and the mixture was further stirred for 1.5 hours while maintaining a temperature of 80 ° C. or higher. Then, it cooled to room temperature and obtained the vinyl acetate resin-type emulsion. The solid content of this vinyl acetate resin emulsion was 42% by mass.

(Comparative Example 1)
The dripping amount of the vinyl acetate monomer is changed to 270 parts by mass instead of 240 parts by mass, and instead of the mixture of the liquid plasticizer and the powdered water-soluble polymer compound, the liquid plasticizer (1) ( Diisobutyl adipate): A vinyl acetate resin emulsion was obtained in the same manner as in Example 1 except that 30 parts by mass was used. That is, 606 parts by mass of water was placed in a reaction vessel equipped with a stirrer, a reflux condenser, a dropping tank, and a thermometer, and with stirring, PVA (1) (trade name “Kuraray Poval 217”, Kuraray Co., Ltd.) 25 parts by mass, PVA (2) (trade name “Kuraray Poval 117”, manufactured by Kuraray Co., Ltd.): 25 parts by mass and tartaric acid: 1 part by mass were added and dissolved, and kept at 80 ° C. After polyvinyl alcohol [PVA (1) and PVA (2)] is completely dissolved, a catalyst (35% by mass hydrogen peroxide solution: an aqueous solution in which 1 part by mass is dissolved in 20 parts by mass of water) and a vinyl acetate monomer : 270 parts by mass were continuously added dropwise from separate dropping tanks over 2 hours. After completion of dropping, 30 parts by mass of liquid plasticizer (1) (diisobutyl adipate) as a liquid plasticizer was added, and the mixture was further stirred for 1.5 hours while maintaining a temperature of 80 ° C. or higher. Then, it cooled to room temperature and obtained the vinyl acetate resin-type emulsion. The solid content of this vinyl acetate resin emulsion was 38% by mass.

(Comparative Example 2)
The amount of PVA (1) used is 40 parts by mass instead of 25 parts by mass, the amount of PVA (2) is 40 parts by mass instead of 25 parts by mass, and the liquid plasticizer and powdered water-soluble polymer Instead of the mixture with the compound, a liquid plasticizer (1) (diisobutyl adipate) as a liquid plasticizer: a vinyl acetate resin emulsion was obtained in the same manner as in Example 1 except that 30 parts by mass was used. . That is, 606 parts by mass of water was placed in a reaction vessel equipped with a stirrer, a reflux condenser, a dropping tank, and a thermometer, and with stirring, PVA (1) (trade name “Kuraray Poval 217”, Kuraray Co., Ltd.) 40 parts by mass, PVA (2) (trade name “Kuraray Poval 117”, manufactured by Kuraray Co., Ltd.): 40 parts by mass and tartaric acid: 1 part by mass were dissolved and kept at 80 ° C. After polyvinyl alcohol [PVA (1) and PVA (2)] is completely dissolved, a catalyst (35% by mass hydrogen peroxide solution: an aqueous solution in which 1 part by mass is dissolved in 20 parts by mass of water) and a vinyl acetate monomer : 240 parts by mass were continuously dropped from separate dropping tanks over 2 hours. After completion of dropping, 30 parts by mass of liquid plasticizer (1) (diisobutyl adipate) as a liquid plasticizer was added, and the mixture was further stirred for 1.5 hours while maintaining a temperature of 80 ° C. or higher. Then, it cooled to room temperature and obtained the vinyl acetate resin-type emulsion. The solid content of this vinyl acetate resin emulsion was 38% by mass.

(Comparative Example 3)
The dropping amount of the vinyl acetate monomer is changed to 270 parts by mass instead of 240 parts by mass, and instead of the mixture of the liquid plasticizer and the powdered water-soluble polymer compound, the liquid polymer (1) ( Product name “ARUFON UP-1000” (manufactured by Toa Gosei Co., Ltd.): A vinyl acetate resin emulsion was obtained in the same manner as in Example 1 except that 30 parts by mass was used. That is, 606 parts by mass of water was placed in a reaction vessel equipped with a stirrer, a reflux condenser, a dropping tank, and a thermometer, and with stirring, PVA (1) (trade name “Kuraray Poval 217”, Kuraray Co., Ltd.) 25 parts by mass, PVA (2) (trade name “Kuraray Poval 117”, manufactured by Kuraray Co., Ltd.): 25 parts by mass and tartaric acid: 1 part by mass were added and dissolved, and kept at 80 ° C. After polyvinyl alcohol [PVA (1) and PVA (2)] is completely dissolved, a catalyst (35% by mass hydrogen peroxide solution: an aqueous solution in which 1 part by mass is dissolved in 20 parts by mass of water) and a vinyl acetate monomer : 270 parts by mass were continuously added dropwise from separate dropping tanks over 2 hours. After completion of the dropping, liquid polymer (1) as a liquid polymer compound (trade name “ARUFON UP-1000”, manufactured by Toagosei Co., Ltd.): 30 parts by mass was added, and the temperature was maintained at 80 ° C. or higher. Stir for 1.5 hours. Then, it cooled to room temperature and obtained the vinyl acetate resin-type emulsion. The solid content of this vinyl acetate resin emulsion was 38% by mass.

(Comparative Example 4)
Instead of a mixture of a liquid plasticizer and a powdery water-soluble polymer compound, a liquid plasticizer (1) (diisobutyl adipate) as a liquid plasticizer: 30 parts by mass and a liquid polymer (1) as a liquid polymer compound ( Trade name “ARUFON UP-1000”, manufactured by Toa Gosei Co., Ltd .: A vinyl acetate resin emulsion was obtained in the same manner as in Example 1 except that 30 parts by mass of the mixture was used. That is, 606 parts by mass of water was placed in a reaction vessel equipped with a stirrer, a reflux condenser, a dropping tank, and a thermometer, and with stirring, PVA (1) (trade name “Kuraray Poval 217”, Kuraray Co., Ltd.) 25 parts by mass, PVA (2) (trade name “Kuraray Poval 117”, manufactured by Kuraray Co., Ltd.): 25 parts by mass and tartaric acid: 1 part by mass were added and dissolved, and kept at 80 ° C. After polyvinyl alcohol [PVA (1) and PVA (2)] is completely dissolved, a catalyst (35% by mass hydrogen peroxide solution: an aqueous solution in which 1 part by mass is dissolved in 20 parts by mass of water) and a vinyl acetate monomer : 240 parts by mass were continuously dropped from separate dropping tanks over 2 hours. After completion of dropping, 30 parts by mass of liquid plasticizer (1) (diisobutyl adipate) as a liquid plasticizer and liquid polymer (1) as a liquid polymer (trade name “ARUFON UP-1000”, Toa Gosei Co., Ltd. Product): A mixture with 30 parts by mass was added, and the mixture was further stirred for 1.5 hours while maintaining a temperature of 80 ° C. or higher. Then, it cooled to room temperature and obtained the vinyl acetate resin-type emulsion. The solid content of this vinyl acetate resin emulsion was 38% by mass.

(Evaluation)
About the vinyl acetate resin-type emulsion obtained in Examples 1-8 and Comparative Examples 1-4, fluidity | liquidity, the minimum film forming temperature, and adhesive performance were evaluated by the following method. The evaluation results are shown in Table 1.

(Evaluation method for fluidity)
The temperature of the vinyl acetate resin emulsion was adjusted to 25 ° C., using a BH viscometer manufactured by Tokimec Co., Ltd., temperature: 25 ° C., rotor: No. 5 (Examples 1 to 7 and Comparative Examples 1 to 4), No. 5 Under the conditions of 6 (Example 8), the viscosity was measured at each rotation speed of the rotor: 2 r / min and 10 r / min, and the TI value represented by the following formula (1) was obtained.
TI value = η _{(2r / min)} / η _{(10r / min)} (1)
[In Formula (1), “η _{(2r / min)} ” indicates the viscosity (Pa · s) when the rotational speed of the rotor is 2 r / min, and “η _{(10r / min)} ” indicates the rotor The viscosity (Pa · s) when the rotational speed is 10 r / min is shown. ]

And fluidity | liquidity was evaluated by the following evaluation criteria using the TI value shown by said Formula (1). The closer the TI value is to 1, the more the viscosity change (particularly the viscosity increase) in the stationary state is suppressed or prevented.
Evaluation criteria (circle): TI value is less than 2.0.
Δ: TI value is 2.0 or more and less than 2.5.
X: TI value is 2.5 or more.

(Measurement method of minimum film-forming temperature)
In accordance with JIS K 6804 (7.6 Minimum film-forming temperature) using a film-formation tester (equipment product name “MFT test equipment” manufactured by Riken Seiki Seisakusho; model number “LT”). The minimum film-forming temperature (° C.) of the vinyl acetate resin emulsion was measured.

(Adhesion performance evaluation method)
As the adhesive performance of the vinyl acetate resin emulsion, various adhesive strengths (normal adhesive strength and water-resistant adhesive strength) were measured by the following measuring methods to evaluate the adhesive performance.
(1) Measuring method of normal-state adhesive strength The compression shear adhesive strength when using each vinyl acetate resin emulsion as a woodworking adhesive was measured according to JIS K 6852. As a test piece, a combination of birch material and birch material was used. In addition, the state of fracture in the adherend was examined, and the ratio of the fractured area to the shear area was determined as the material fracture rate (%). Specifically, 23 ° C., in an atmosphere of RH 50%, was coated on each surface of the specimen (coated amount: one side 100 g / m ^2, both surfaces 200g / m ^2), superposing the coated faces The test specimens were bonded together with a pressure of 1 MPa, cured in an atmosphere of 50% RH for 24 hours, then depressurized and cured in an atmosphere of 23 ° C. and 50% RH for 48 hours. Glued. Thereafter, the compression shear bond strength (N / mm ² ) of the bonded test piece was measured in accordance with JIS K 6852 under an atmosphere of 23 ° C. and 50% RH.

(2) Measuring method of water-resistant adhesive strength The compression shear adhesive strength when using a vinyl acetate resin emulsion as an adhesive for woodworking, in accordance with JIS K 6852, with the test piece wet It was measured. As a test piece, a combination of birch material and birch material was used. Specifically, 23 ° C., in an atmosphere of RH 50%, was coated on each surface of the specimen (coated amount: one side 100 g / m ^2, both surfaces 200g / m ^2), superposing the coated faces The test specimens were bonded together with a pressure of 1 MPa, cured in an atmosphere of 50% RH for 24 hours, then depressurized and cured in an atmosphere of 23 ° C. and 50% RH for 48 hours. Glued. After that, the bonded test piece was immersed in a constant temperature water bath adjusted to 30 ± 1 ° C. for 3 hours, and further immersed in water adjusted to 23 ± 2 ° C. for 10 minutes, then taken out from the water and tested. With the piece wet, the compression shear bond strength (N / mm ² ) of the bonded test piece was measured according to JIS K 6852. In addition, when immersing a test piece in water, the weight was used so that a test piece might be completely immersed in water.

As is clear from Table 1, the vinyl acetate resin emulsion according to the example is a ratio between the viscosity when the rotational speed of the rotor is 2 r / min and the viscosity when the rotational speed of the rotor is 10 r / min. The TI value is less than 2.5, and it was confirmed that an increase in viscosity in a stationary state was suppressed or prevented. The vinyl acetate resin emulsion according to the example has a minimum film forming temperature of 0 ° C. or less according to JIS standard (JIS K 6804), and in that case, a transparent film is formed. Excellent film formability. Furthermore, not only the normal adhesive strength but also the water-resistant adhesive strength measured in a wet state is good, and the adhesive performance is excellent. Therefore, the vinyl acetate resin emulsion according to the example has excellent low-temperature film-forming properties and adhesive strength, and has excellent fluidity.

Claims (9)

A vinyl acetate resin emulsion obtained by polymerizing a monomer component containing at least vinyl acetate, and after polymerizing the monomer component containing at least vinyl acetate, a mixture of a liquid plasticizer and a powdery water-soluble polymer compound A vinyl acetate resin emulsion characterized in that is added. A vinyl acetate resin emulsion obtained by seed polymerization of a monomer component containing at least vinyl acetate in an emulsion containing a polymer of polymerizable unsaturated monomer (X). 2) A mixture of a liquid plasticizer and a powdery water-soluble polymer compound is further added after seed polymerization of a monomer component containing at least vinyl acetate in an emulsion containing a polymer of Vinyl resin emulsion. The vinyl acetate resin emulsion according to claim 1 or 2, wherein the liquid plasticizer is a liquid plasticizer other than a phthalate ester liquid plasticizer. The vinyl acetate resin system according to any one of claims 1 to 3, wherein the liquid plasticizer is a fatty acid ester liquid plasticizer or an aromatic carboxylic acid ester liquid plasticizer other than a phthalate ester liquid plasticizer. Emulsion. The vinyl acetate resin emulsion according to any one of claims 1 to 4, wherein the powdered water-soluble polymer compound is a powdered polyvinyl alcohol polymer and / or a powdered polyvinylpyrrolidone polymer. 2. The mixture of a liquid plasticizer and a powdery water-soluble polymer compound is a mixture of a powdered water-soluble polymer compound covered with a liquid plasticizer or dispersed in a liquid plasticizer. The vinyl acetate resin emulsion as described in any one of -5. The vinyl acetate resin emulsion according to any one of claims 2 to 6, wherein the polymer of the polymerizable unsaturated monomer (X) is an ethylene-vinyl acetate copolymer resin or an acrylic resin. The vinyl acetate resin emulsion according to any one of claims 1 to 7, wherein a polymerizable unsaturated monomer (Y) other than vinyl acetate is used together with vinyl acetate as a monomer component to be subjected to seed polymerization. A method for producing a vinyl acetate resin emulsion according to any one of claims 1 to 8, comprising the following steps (A) to (B): Production method.
Step (A): Step of polymerizing a monomer component containing at least vinyl acetate Step (B): Step of adding a mixture of a liquid plasticizer and a powdered water-soluble polymer compound after step (A)