JPH11349770A - Vinyl resin emulsion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a vinyl resin emulsion having excellent long-term preservation stability and water resistance in formed coated membrane by compounding a polyvinyl alcohol resin containing acetoacetyl groups with a urea compound. SOLUTION: The objective emulsion is obtained by compounding (A) an acetoacetyl group-containing polyvinyl alcohol resin preferably having an average molecular weight of 200-3000 and an acetoacetyl group content of 0.05-15 mol.%, (B) 0.05-4 wt.% of a urea compound and optionally (C) 0.05-2 wt.% of a reductant, and the obtained emulsion preferably has the amount of the residual vinyl monomer of 0.4 wt.% or less and has pH of 3-8. Examples of the component B include (thio)urea,(di)methylurea,(di)ethylurea,ethyleneurea, guanyl(thio)urea and acetylurea. Examples of the component C include a sulfite, a thiosulfate, a (meta)bisulfate, an L-ascorbic acid and a hydrazine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl resin emulsion, and more particularly to a vinyl resin emulsion excellent in long-term storage stability and water resistance of a formed coating film.

[0002]

2. Description of the Related Art Conventionally, (vinyl acetate) -based emulsions have been widely used for adhesives, paints, textile / textile processing agents, paper / leather processing agents, binders for various materials, and cement / mortar admixtures. It is used for various purposes. Among them,
(Acetic acid) vinyl resin emulsion containing acetoacetylated polyvinyl alcohol-based resin can be used as an adhesive for woodworking by using various cross-linking agents to further improve the water resistance, and to cut the adhesive. It has advantages such as not damaging the blade sometimes, and is therefore used for the above-mentioned applications. However, when an acetoacetylated polyvinyl alcohol-based resin is added, the stability of the emulsion decreases (increase in viscosity, generation of a gel, etc.), and thus various additives have been used in combination. For example,
JP-A-36218 discloses the use of a sulfite, a thiosulfate, a bisulfite, a metabisulfite or the like, and JP-A-7-3102 discloses the use of a hydroxyl-containing compound represented by a specific formula. In JP-A-8-113687, a combination of a water-soluble organic amine and a water-soluble hydrazine has been proposed, and the present applicant has also proposed ketones, keto acid esters,
Combined use of malonic acids and the like (Japanese Patent Publication No. 3-50772),
Combined use of sodium acid sulfite (JP-A-7-138305) and combination use of mercaptans (JP-A-7-138306)
Publication).

[0003]

However, Japanese Patent Publication No. 60-36218 and Japanese Patent Application Laid-Open No.
JP-B-3-50772, JP-A-7-138305
JP-A-7-138306, the use of additives described in JP-A-7-138306 can provide a certain degree of storage stability, but the stability at high and low temperatures in summer and winter is not sufficient, and after long-term storage. Poor film strength and poor adhesiveness when used as an adhesive, still unsatisfactory.
When the additive described in JP 13687 is used in combination, gelation can be prevented, but the viscosity of the emulsion increases, and when it is used for an adhesive or the like, there is a drawback that a stable adhesive force cannot be obtained depending on the time of use. New improvements are desired.

[0004]

Means for Solving the Problems In view of the above circumstances, the present inventors have conducted intensive studies. As a result, the acetoacetyl group-containing polyvinyl alcohol-based resin and the vinyl resin-based emulsion containing the urea-based compound can be used in summer or summer. The present invention has been found to provide an emulsion that exhibits sufficient stability even at a high temperature or a low temperature in winter and that can maintain the film strength after long-term storage and the adhesive strength when used as an adhesive. Was completed.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
Acetoacetylated polyvinyl alcohol resin used in the present invention (hereinafter sometimes abbreviated as AA-PVA)
Can be obtained by reacting a polyvinyl alcohol-based resin (hereinafter sometimes abbreviated as PVA) with diketene by a known method. For example, PVA is dispersed in an acetic acid solvent, and diketene is added thereto. In this method, PVA is previously dissolved in a solvent such as dimethylformamide or dioxane, and diketene is added thereto. A method for obtaining AA-PVA by directly contacting PVA with diketene gas or liquid diketene, or adding an acid catalyst such as sulfuric acid to a saponified slurry of an alcoholic solvent for PVA to transesterify acetoacetate to obtain AA-P
A method of obtaining VA can be employed.

The average degree of polymerization of the AA-PVA is not particularly limited, but is preferably from 200 to 3,000, more preferably from 40 to 3,000.
If the average degree of polymerization is less than 200, it is difficult to obtain a protective colloid as an emulsifier described later, and the emulsion has poor stability during emulsion polymerization. Conversely, if it exceeds 3,000, an emulsion obtained when used as an emulsifier The viscosity increases, which is not preferable. Also, a raw material P for AA-PVA
The average degree of saponification of VA is preferably 68 to 100 mol%,
Further, it is preferably in the range of 80 to 100 mol%, and the AA-PVA obtained when the average saponification degree is less than 68 mol% is obtained.
Is not preferred because it becomes insoluble in water. Furthermore, AA-PVA
Acetoacetyl group content (AA degree) of 0.05 to
When the AA degree is less than 0.05 mol%, the water resistance when the emulsion is formed into a coating film tends to decrease. If it exceeds mol%, the emulsion viscosity is too high and the storage stability tends to decrease, which is not preferred.

In the present invention, the AA-P
It is possible to use not only VA alone, but also other PVAs, and furthermore, two or more kinds of A having different degrees of saponification and the like.
It is also possible to use A-PVA. Such AA-P
The content of VA is preferably selected from the range of 0.1 to 30% by weight (more preferably 1 to 10% by weight) based on the whole of the vinyl resin emulsion of the present invention. When the amount is less than 30% by weight, the water resistance of the emulsion when formed into a coating film is reduced. On the other hand, when the amount is more than 30% by weight, the emulsion viscosity is too high and the storage stability is undesirably reduced.

The vinyl acetate resin emulsion of the present invention containing the AA-PVA as described above is usually obtained by emulsion polymerization of a vinyl compound. Examples of such a vinyl compound include vinyl acetate, vinyl propionate, and ( Meta)
Acrylic acid ester, vinyl chloride, vinylidene chloride,
Examples thereof include (meth) acrylonitrile, styrene, ethylene, propylene, and an acetoacetyl group-containing acrylic monomer. These are homopolymerization or copolymerization, or copolymerization with a diene monomer such as butadiene. In particular, vinyl acetate alone or a copolymer mainly composed of vinyl acetate is preferred. As the emulsion polymerization catalyst, a radical generator, in particular, a water-soluble catalyst is preferably used.For example, peroxides such as hydrogen peroxide, tartaric acid, formic acid,
Reducing agents such as oxalic acid; water-soluble azobis such as 2,2-azobis (2-amidinopropane) diacid; ammonium persulfate, potassium persulfate; t-butylperoxyacetate; t-butylperoxybenzoate; Or two or more of these are used, and preferably, t-butyl peroxyacetate or t-butyl peroxyacetate or t-butyl peroxyacetate in the sense that the residual amount of a persulfate-based catalyst such as ammonium persulfate or potassium persulfate or a vinyl monomer can be reduced. Oxybenzoate is preferably used.

Various surfactants such as nonionic surfactants and anionic surfactants can be used in combination with AA-PVA.
Still other emulsifiers such as cellulose derivatives (carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, etc.), polyvinyl alcohols, polyacrylic acid derivatives, maleic anhydride-vinyl ether copolymer, maleic anhydride-vinyl acetate copolymer And a saponified product of vinyl acetate- (meth) allylsulfonic acid (salt) copolymer and the like can also be appropriately used.

In the present invention, the AA-PV as described above is used.
The most characteristic feature is that a urea compound is contained in the vinyl resin emulsion containing A. Examples of the urea compound include urea, thiourea, methyl urea,
Examples thereof include ethyl urea, dimethyl urea, diethyl urea, ethylene urea, guanyl urea, guanyl thiourea, and acetyl urea, and thiourea is preferably used, but is not limited thereto.

The content of the urea compound is preferably 0.05 to 4% by weight in the vinyl emulsion, more preferably 0.05 to 2% by weight, and the content is 0.05% by weight. If it is less than 10%, the storage stability of the emulsion decreases, and if it exceeds 4% by weight, the water resistance of the emulsion tends to decrease slightly and the sulfur odor tends to increase, which is not preferable. The method of adding the urea-based compound is not particularly limited, and may be at any time during polymerization, after polymerization, or the like.
In order to obtain better water resistance of the film, it is preferable after polymerization, and it may be left in a solid state at the time of addition, but it is more preferable to add it as an aqueous solution.

In the present invention, it is preferable to further include a reducing agent such as a sulfite, a thiosulfate, a bisulfite, a metabisulfite, L-ascorbic acid, and hydrazines. Is sodium sulfite,
Potassium sulfite, ammonium sulfite, sodium thiosulfate, potassium thiosulfate, ammonium thiosulfate, sodium bisulfite, ammonium bisulfite, sodium metabisulfite, potassium metabisulfite, L-ascorbic acid, hydrazine sulfate, hydrazine hydrochloride, hydrazine carbonate, substitution Hydrazine, hydrazine phosphate, methyl hydrazine and the like can be mentioned. Preferably, sodium bisulfite is used, and its content is 0.05 to 2% by weight (further 0.1 to 1% by weight). When the content is less than 0.05% by weight, the storage stability of the emulsion cannot be expected to be much improved. On the contrary, when the content exceeds 2% by weight, the water resistance and adhesive strength of the film are undesirably reduced. The addition of these reducing agents may be during or after the polymerization, but is preferably performed after the polymerization. The addition may be performed in a solid state, but is preferably performed as an aqueous solution.

Thus, the (acetic acid) vinyl resin-based emulsion of the present invention containing the acetoacetyl group-containing polyvinyl alcohol-based resin and the urea-based compound can be obtained. The residual amount is 0.4% by weight or less, and more preferably 0.4% by weight.
It is also preferred that the content be 3% by weight or less, particularly 0.2% by weight or less, and that the pH of such an emulsion be 3 to 8, more preferably 4 to 7. The method for controlling the residual amount of the vinyl monomer in the emulsion to 0.4% by weight or less is not particularly limited. For example, during the emulsion polymerization of the (acetic acid) vinyl compound as described above, isopropyl alcohol is allowed to coexist. A method of adding butyl alcohol after the addition of the polymerization catalyst, a method of adding an alkali metal salt of silicic acid to a residual (acetic acid) vinyl monomer in a (acetic acid) vinyl resin emulsion containing AA-PVA, Although a method of raising the polymerization temperature at the time is mentioned, the method is industrially useful, and such a method will be described in more detail.

In the above method, the coexistence amount of isopropyl alcohol is 0.1 to 100 parts by weight of the vinyl compound.
The amount is preferably 2 to 2 parts by weight (more preferably 0.5 to 1.5 parts by weight). If the amount is less than 0.2 parts by weight, the effect of reducing the residual amount of the vinyl monomer is not sufficient. Is 2
Exceeding the weight part is not preferred because the viscosity stability of the emulsion decreases. Further, the addition amount of butyl alcohol to be added after the completion of the dropwise addition of the polymerization catalyst is 0.05 to 0.3 parts by weight (more preferably 0.1 to
When the amount is less than 0.05 part by weight, the effect of reducing the residual amount of the vinyl monomer is not sufficient. Conversely, when the amount exceeds 0.3 part by weight, Does not contribute to the reduction of the remaining amount.

In the above method, sodium silicate (sodium metasilicate, sodium orthosilicate, sodium disilicate, sodium tetrasilicate, etc.), potassium silicate (potassium metasilicate, potassium hydrogen disilicate, etc.), silicate Lithium (lithium metasilicate, lithium orthosilicate, etc.) and hydrates thereof can be mentioned. Preferably, the content (addition) of an alkali metal salt of silicic acid such as sodium silicate or potassium silicate is used. The content may be set to 0.01 to 4% by weight (further 0.02 to 2% by weight). When the content is less than 0.01% by weight, the effect of reducing the residual monomer is poor. Exceeding this is undesirable because the stability of the emulsion and the strength of the film decrease. The method of controlling the pH of the emulsion is not particularly limited, and may be adjusted by adding, for example, various organic or inorganic acid metal salts or amines.
More specifically, sodium acetate, sodium phosphate,
Sodium carbonate, aluminum acetate, magnesium acetate and the like are added to the emulsion in an amount of about 0.01 to 5% by weight (based on the emulsion) (the timing of addition may be either during or after polymerization, and is not particularly limited. 90%
It is preferable to add at the above time).

In the above-mentioned polymerization, various additives used in ordinary emulsion polymerization can be used. In the present invention, polyethylene glycol, mercaptans (alkyl mercaptan, aromatic mercaptan), sulfides ( Use of a chain transfer agent such as dibutyl disulfide, diacetyl disulfide, diethyl dithioglycate) or a nitrogen-containing compound (methyl cyanoacetate, nitromethane, benzyl cyanide) is useful for the stability of the emulsion. The amount is preferably 0.01 to 5% by weight, more preferably 0.02 to 2% by weight, based on the vinyl monomer. When the amount is less than 0.01% by weight, the storage stability of the emulsion is hardly obtained. If it exceeds 5% by weight, the water resistance of the emulsion film is lowered, which is preferable. Not properly.

A plasticizer such as dibutyl phthalate, dioctyl phthalate, or butyl carbitol may be added for adjusting the minimum film forming temperature and the like, and adipoi for improving the water resistance of the emulsion film. Modified by adding a water-soluble aliphatic dihydrazide such as rudihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, adipic acid dihydrazide, or by mixing a phenolic resin initial condensate or resorcinol initial condensate. It can be handled as a vinyl acetate emulsion. AA-PVA as described above
Is used as an emulsifier to obtain an (AA) PVA-containing (Acetate) vinyl resin emulsion by coexisting during the polymerization of the (Acetate) vinyl compound. (Acetic acid) of the present invention
Of course, a vinyl resin emulsion can be used.

The thus-obtained (acetic acid) vinyl resin emulsion of the present invention can be used for adhesives, binders, coating agents for paper, wood, plastics, fibers, wallpaper, etc.
It is used as a paint, especially for high-speed mechanization of woodworking and paper bonding, and is also excellent in water resistance, so it is useful for bonding applications such as plywood and water-resistant corrugated cardboard. It is also useful to use for supplementing formaldehydes in wood (adhesives, paints, coatings, etc.).

[0019]

Next, the present invention will be described more specifically with reference to examples. In the examples, “parts” and “%” are based on weight unless otherwise specified. Example 1 10.8 parts of a vinyl acetate monomer and an average degree of polymerization of 1400,
AA having an average saponification degree of 99 mol% and an AA degree of 5.5 mol%
120 parts of a 10% aqueous PVA solution, 10 parts of a 0.6% aqueous sodium acetate solution, 37 parts of water, and 5 parts of a 0.96% aqueous ammonium persulfate solution were stirred with a stirrer, a reflux condenser, a dropping funnel,
The mixture was charged into a separable flask equipped with a thermometer, and the temperature in the flask was increased to 70 ° C. with stirring to perform initial polymerization for 1 hour. Next, 97.2 parts of vinyl acetate monomer was added dropwise over 3 hours, and 5 parts of a 0.96% ammonium persulfate aqueous solution was added.
A 96% aqueous solution of ammonium persulfate was added three times. One hour after the completion of the addition of the vinyl acetate monomer, 1 part of a 1% aqueous solution of hydroquinone was added to terminate the polymerization. Finally, 0.8 parts of thiourea was added to obtain a vinyl acetate resin emulsion of the present invention. The amount of residual vinyl acetate monomer in the obtained vinyl acetate resin emulsion was 0.4%, and the polymerization rate was 98.9.
%, PH 2.6, and viscosity 28,000 mPa · s (BH type rotational viscometer, rotor rotation speed 10 rpm, 25 ° C.). Using the above-mentioned vinyl acetate resin emulsion, the stability of standing and the water resistance of the resulting coating film were evaluated as follows.

(Stability on standing) The obtained vinyl acetate resin emulsion was sealed in a 450 ml mayonnaise bottle,
The viscosities after standing at 70 ° C. for 7 days and after standing at room temperature for one year are measured to determine how many times the viscosity before standing (the same method as above) (viscosity after standing / viscosity before standing). Was. In addition, the measurement of the viscosity was all performed at 25 degreeC. (Stability of water-resistant adhesive strength) Rawan material (25 mm x 50 m
m, thickness 10 mm), and apply the obtained vinyl acetate emulsion to a surface of 100 g / m ^2.
Half of the area (25m)
mx 25mm), 10kg
/ Cm ² at 20 ° C for 1 hour.
The specimen was cured at 48 ° C. and 65% RH for 48 hours.
Next, the obtained specimen was boiled for 4 hours, dried at 60 ° C. for 3 hours, and measured at 20 ° C. for compression shear adhesive strength at a compression speed of 10 mm / min, and evaluated as follows.
The measured value was an average value of n = 10, and the vinyl acetate emulsion left at room temperature for 6 months was similarly evaluated. ○ --- 30kg / cm ² or more △ --- 1~30kg / cm ² less × --- 1kg / cm ^2, or less than peeling the specimen before the measurement was observed (low-temperature stability) The obtained acetate The vinyl resin emulsion was sealed in a 450 ml mayonnaise bottle, left in a 0 ° C. thermostat for 3 hours, and the viscosity immediately after being taken out was measured. The emulsion was further left in a 0 ° C. thermostat for 1 month, and The viscosity was measured to determine how many times the viscosity before standing for one month (viscosity after standing for one month / 3 viscosity after standing for 3 hours).

Example 2 The procedure of Example 1 was repeated except that 2 parts of a 40% aqueous solution of sodium bisulfite was further added. The amount of the remaining vinyl acetate monomer was 0.4%, the conversion was 98.9%, and the pH was 2.0.
6. A vinyl acetate resin emulsion having a viscosity of 27,000 mPa · s (same as above) was obtained and similarly evaluated.

Example 3 The procedure of Example 1 was repeated, except that 5 parts of a 10% aqueous sodium silicate solution was added simultaneously with the thiourea.
Residual vinyl acetate monomer amount 0.3%, conversion 99.1
%, A pH of 5.3, and a viscosity of 26000 mPa · s (same as above) to obtain a vinyl acetate resin emulsion, which was similarly evaluated.

Example 4 The procedure of Example 1 was repeated except that the amount of thiourea was changed to 4 parts.
Polymerization rate 98.8%, pH 3.6, viscosity 27000 mPa
-A vinyl acetate resin emulsion of s (same as above) was obtained and similarly evaluated.

Example 5 The procedure of Example 1 was repeated, except that 1 part of a 15% aqueous sodium acetate solution was added simultaneously with thiourea. The remaining vinyl acetate monomer amount was 0.4%, the polymerization rate was 98.9%, and the p
A vinyl acetate resin emulsion having an H of 5.1 and a viscosity of 27,000 mPa · s (same as above) was obtained and similarly evaluated.

Example 6 A mixed solution composed of 108 parts of vinyl acetate monomer and 2 parts of isopropyl alcohol was prepared in advance, 11 parts of the mixed solution, average degree of polymerization was 1400, average degree of saponification was 99 mol%, and degree of AA was 5 120 parts of a 10% aqueous solution of 0.5 mol% AA-PVA, 120 parts of a 0.6% aqueous sodium acetate solution, 37 parts of water, and 5 parts of a 0.96% aqueous ammonium persulfate solution were stirred with a stirrer, a reflux condenser, a dropping funnel, and a temperature. The mixture was charged into a separable flask equipped with a meter, and the temperature in the flask was set to 70 ° C. with stirring to carry out initial polymerization for 1 hour. Next, 99 parts of the remaining liquid mixture was added dropwise over 3 hours,
5 parts of a 6% ammonium persulfate aqueous solution was added, and the same amount of a 0.96% ammonium persulfate aqueous solution was further added three times every hour. At the same time as vinyl acetate monomer dropping,
0.3 parts of butyl alcohol was added, and one hour later, 1 part of a 1% aqueous solution of hydroquinone was added to terminate the polymerization.
Finally, 0.8 parts of thiourea and 1 part of a 15% aqueous sodium acetate solution were added to obtain a vinyl acetate resin emulsion. The amount of residual vinyl acetate monomer in the obtained vinyl acetate resin emulsion was 0.2%, the polymerization rate was 99.4%, and the pH was 4.
9, viscosity was 26000 mPa · s (same as above).

Example 7 Polymerization was started in the same manner as in Example 6, and butyl alcohol 0.3
At the time of addition, 1 part of a 15% aqueous sodium acetate solution was added (at this time, the polymerization rate was 96%, and the pH was 4.7). After one hour, the polymerization was terminated. The residual vinyl acetate monomer amount was 0.2%, the polymerization rate was 99.4%, the pH was 4.7, and the viscosity was 24.
000 mPa · s (same as above) was obtained and evaluated similarly.

Example 8 The procedure of Example 6 was repeated, except that the aqueous sodium acetate solution was replaced with 3
Polymerization was carried out in the same manner except that 10 parts of a 0% aqueous sodium carbonate solution was used. The remaining vinyl acetate monomer amount was 0.2%, the polymerization rate was 99.4%, the pH was 7.2, and the viscosity was 25,000 mPa · s.
s (same as above) was obtained and similarly evaluated.

Example 9 The procedure of Example 6 was repeated except that, finally, 0.4 part of thiourea and 1 part of a 40% aqueous sodium bisulfite solution were added. 9
A vinyl acetate resin emulsion having 9.4%, pH 5.0, and viscosity of 24,000 mPa · s (same as above) was obtained and evaluated in the same manner.

Example 10 Polymerization was carried out in the same manner as in Example 1 except that urea was changed to 0.8 parts instead of thiourea. The amount of the remaining vinyl acetate monomer was 0.4%, the conversion was 98.9%, and the pH was 2. .8, viscosity 2
A vinyl acetate resin emulsion of 8000 mPa · s (same as above) was obtained and evaluated similarly.

Comparative Example 1 The procedure of Example 1 was repeated, except that thiourea was not added. The amount of residual vinyl acetate monomer was 0.4%, the conversion was 98.9%, the pH was 2.5, and the viscosity was 27,000 mPa · s.
A vinyl acetate resin emulsion (same as above) was obtained and evaluated similarly.

[0031]

[Table 1] Leaving stability Stability of water-resistant adhesive strength Low temperature stability 70 ° C × 7 days Room temperature × 6 months Initial room temperature × 6 months Example 1 2.4 2.5 ○ △ 1.3 〃 2 2.3 2 1.4 △ 1.5 ３ 3 1.2 1.2 ○ 1.3 〃 4 2.2 2.3 〃 1.2 ５ 5 2.3 2.5 △ 1.4 ６ 6 1. 0 1.0 ○ ○ 1.0 〃 7 1.0 1.0 ○ ○ 1.1 〃 8 1.7 2.0 ○ △ 1.5 ９ 9 1.2 1.2 ○ ○ 1.2 〃 10 2.4 2.6 ○ △ 1.4 Comparative Example 1 Gelation Gelation ○ × 3.5

[0032]

Since the (acetic acid) vinyl resin emulsion of the present invention contains an acetoacetyl group-containing polyvinyl alcohol-based resin and a urea-based compound, the emulsion has a standing (preservation) stability and a water-resistant coating film. It is particularly useful for applications such as woodworking adhesives and paper tube adhesives that require water / hot water resistance.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI // (C08L 31/04 29:04)

Claims (11)

[Claims] 1. A vinyl resin emulsion comprising an acetoacetyl group-containing polyvinyl alcohol resin and a urea compound. 2. The method according to claim 1, wherein the urea compound is at least one selected from urea, thiourea, methylurea, ethylurea, dimethylurea, diethylurea, ethyleneurea, guanylurea, guanylthiourea, and acetylurea. Item 4. The vinyl resin emulsion according to Item 1. 3. The vinyl resin emulsion according to claim 1, wherein the content of the urea compound is 0.05 to 4% by weight. 4. The method according to claim 1, further comprising at least one reducing agent selected from the group consisting of sulfites, thiosulfates, bisulfites, metabisulfites, L-ascorbic acid and hydrazines. 4. The vinyl resin emulsion according to any one of claims 1 to 3. 5. The vinyl resin emulsion according to claim 4, wherein the content of the reducing agent is 0.05 to 2% by weight. 6. The residual amount of the vinyl monomer is 0.4% by weight.
The vinyl resin emulsion according to any one of claims 1 to 5, wherein: 7. The method according to claim 1, wherein a vinyl monomer is dropped and polymerized in the presence of isopropyl alcohol, and butyl alcohol is added after dropping the polymerization catalyst.
7. The vinyl resin emulsion according to any one of claims 6 to 6. 8. The vinyl resin emulsion according to claim 1, further comprising an alkali salt of silicic acid. 9. The content of an alkali salt of silicic acid is 0.01
The vinyl resin emulsion according to claim 8, wherein the amount is from 4 to 4% by weight. 10. The vinyl resin emulsion according to claim 1, wherein the pH is 3 to 8. 11. The vinyl resin emulsion according to claim 1, which is used for coating or impregnating wood to capture formaldehyde in the wood.