JP3178893B2 - Vinyl acetate emulsion and method for reducing its odor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl acetate emulsion having a low odor of vinyl acetate and acetic acid, and a method for reducing the odor of a vinyl acetate emulsion.

[0002]

2. Description of the Related Art Vinyl acetate emulsions are used in a wide variety of applications such as adhesives, paints and coatings. In the vinyl acetate-based emulsion, since vinyl acetate has high hydrophilicity, a vinyl acetate monomer which is an unpolymerized component is usually present and emits a vinyl acetate odor and an acetic odor. When a vinyl acetate emulsion is stored for a long period of time, acetic acid remains in the emulsion although vinyl acetate is easily volatilized. Therefore, the workability of manufacturing the adhesive and the like is reduced, and the working environment is deteriorated.

In order to remove acetic acid odor and vinyl acetate odor, it is conceivable to heat a vinyl acetate emulsion under reduced pressure. However, in such a method, since acetic acid and vinyl acetate are hydrophilic, it is difficult to reduce the dissolved concentration of acetic acid and vinyl acetate to a specific concentration or less, and acetic acid odor and vinyl acetate odor are completely removed. Can not do it. In addition, it takes a long time to remove acetic acid odor and vinyl acetate odor.

Japanese Patent Publication No. 63-57575 discloses a method for suppressing the generation of free acetic acid during high-temperature molding, in which an alkali metal salt or an alkaline earth metal hydrogen phosphate is added to an ethylene-vinyl acetate copolymer. A method is disclosed. According to this method, generation of acetic acid during high-temperature molding can be suppressed, but vinyl acetate odor cannot be reduced. In addition, when the alkali metal salt or the like is added to an aqueous vinyl acetate emulsion, vinyl acetate is hydrolyzed, and acetic acid generated tends to generate an odor of acetic acid. Further, unlike the ethylene-vinyl acetate copolymer used for the high-temperature molding, when an alkaline earth metal salt or the like is added to the vinyl acetate emulsion of the dispersion system, the dispersion stability may be impaired.

Accordingly, an object of the present invention is to provide a high stability,
It is an object of the present invention to provide a vinyl acetate emulsion in which the odor of vinyl acetate and acetic acid odor are significantly reduced.

Another object of the present invention is to provide a method for reducing the odor of a vinyl acetate emulsion which can reduce the odor of vinyl acetate and the odor of acetic acid by a simple operation.

[0007]

SUMMARY OF THE INVENTION We, the object of intensive investigations to achieve results, the addition of water-soluble silicate San'a alkali metal salts, without loss of stability of the emulsion, vinyl acetate odor is significantly reduced, The inventors have found that no acetic acid odor is generated, and have completed the present invention.

[0008] That is, the present invention relates to a vinegar in an emulsion.
100 parts by weight of vinyl acid polymer
Providing vinyl acetate-based emulsion containing the San'a alkali metal salts 0.01 to 10 parts by weight.

Further, the present invention is the vinyl acetate-based emulsion, vinyl acetate-based water-soluble silicate San'a alkali metal salts of poly
Also provided is a method for reducing the odor of a vinyl acetate emulsion by adding 0.01 to 10 parts by weight to 100 parts by weight of a mer .

The present invention can be applied to various vinyl acetate emulsions containing a vinyl acetate monomer as a constituent. The vinyl acetate emulsion is not limited to, for example, a polyvinyl acetate emulsion, and includes a vinyl acetate copolymer emulsion of vinyl acetate and a copolymerizable monomer.

As the copolymerizable monomer, a conventional monomer,
For example, olefins such as ethylene; acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isobutyl acrylate, t-butyl acrylate, hexyl acrylate, octyl acrylate, acrylic acid Acrylic monomers such as 2-ethylhexyl, stearyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and glycidyl acrylate;
Methacrylic monomers corresponding to acrylic monomers; maleic esters such as diethyl maleate, dipropyl maleate, dibutyl maleate, dihexyl maleate, dioctyl maleate, 2-ethylhexyl maleate, and fumal corresponding thereto Acid esters; vinyl esters such as vinyl propionate, vinyl caprylate, vinyl caproate and vinyl versatate; crotonic acid, itaconic acid, itaconic half ester, maleic acid,
Monomers having a carboxy group such as maleic acid half ester; styrene, vinyl chloride, methyl vinyl ketone, acrylonitrile, methacrylonitrile, acrolein,
Crotonaldehyde is exemplified. The vinyl ester also includes a vinyl ester called VeoVa. These copolymerizable monomers can be used alone or in combination of two or more.

[0012] Among these copolymerizable monomers, ethylene, acrylic monomers, methacrylic monomers, maleic esters and vinyl esters are frequently used.

The proportion of vinyl acetate can be selected according to the use of the vinyl acetate emulsion, the glass transition temperature, the minimum film forming temperature, and the like.
It is about 00% by weight, preferably about 25 to 100% by weight, and more preferably about 50 to 100% by weight.

[0014] Vinyl acetate-based emulsions include, in addition to polyvinyl acetate and vinyl acetate copolymers (hereinafter collectively referred to as vinyl acetate-based polymers), conventional components used in emulsion polymerization, for example, anionic or nonionic. Surfactants such as polyvinyl alcohol, hydroxyethylcellulose, and gums, and protective colloids composed of water-soluble oligomers.

The vinyl acetate emulsion is prepared by using the above-mentioned surfactant and / or protective colloid and a polymerization initiator.
It is obtained by emulsion polymerization of the monomer by a conventional method. The emulsion polymerization may be performed in the presence of a chain transfer agent or a buffer.

[0016] The vinyl acetate emulsion of the present invention comprises water
It contains soluble silicate San'a alkali metal salt. Water-soluble silicic acid
The A alkali metal salt, for example, sodium metasilicate, sodium orthosilicate, sodium disilicate, sodium silicate, such as tetrasodium silicate; potassium metasilicate, (potassium tetraborate silicate) disilicate of potassium hydrogen
Potassium silicate; lithium silicate such as lithium metasilicate and lithium orthosilicate; and hydrates thereof. These water-soluble alkali metal silicates can be used alone or in combination of two or more.

[0017] Among these water-soluble silicate San'a alkali metal salt, usually sodium silicate, potassium silicate and their hydrates, especially sodium silicate and its hydrates are frequently used.

[0018] The content of the water-soluble silicates San'a alkali metal salt,
It can be selected according to the concentration of vinyl acetate contained in the vinyl acetate-based emulsion, and is usually 0.01 to 10 parts by weight as an anhydride, preferably 100 parts by weight of the vinyl acetate-based polymer (solid content) in the emulsion. Is 0.1 to 5
Parts by weight, more preferably about 0.5 to 3.5 parts by weight. The content of the water-soluble silicate San'a alkali metal salt is 0.01
If the amount is less than 10 parts by weight, the deodorizing effect of vinyl acetate is small, and
If the amount is more than 10 parts by weight, the pH of the vinyl acetate emulsion may be increased and the film properties may be deteriorated.

[0019] The content of the water-soluble silicate San'a alkali metal salt to the solid content of 100 parts by weight of the total vinyl acetate emulsion, taking into account the content of the component such as a surfactant or a protective colloid in the emulsion Selection Yes, but usually
The same amounts as above are sufficient.

The vinyl acetate based emulsion of the present invention, by emulsion polymerization in the presence of a water-soluble silicate San'a alkali metal salt to the reaction system, but may contain a water-soluble silicate San'a alkali metal salt, emulsifying by adding the vinyl acetate emulsion obtained by polymerization, preferably contains a water-soluble silicate San'a Le <br/> alkali metal salt.

[0021] In the low-odor process of the present invention, the vinyl acetate-based emulsion, 100 double vinyl acetate polymer
Relative to the amount unit, 0.01 to soluble silicate San'a alkali metal salt
Add 10 parts by weight . Soluble silicates San'a alkaline salt, under stirring, it is also added in powder form, usually added as an aqueous solution. The concentration of the water-soluble alkali metal silicate in aqueous solution can be suitably selected according to the type and viscosity of the water-soluble alkali metal silicate. As the aqueous solution, an aqueous solution generally containing about 1 to 30% by weight of a water-soluble alkali metal silicate can be used.

The water-soluble silicate San'a alkali metal salts not only the remaining amount of vinyl acetate, the residual amount of acetic acid also has features that significantly reduced. In addition, water-soluble silicates San'a alkali metal salt,
Controls the hydrolysis of vinyl acetate. Therefore, the water-soluble Ke <br/> Lee San'a alkali metal salt large amount can be suppressed by-production of acetic acid be added, even after long-term storage, it can significantly reduce the residual amount of acetic acid in the emulsion.

Incidentally, soda ash, triethanolamine,
When sodium dihydrogen phosphate, disodium hydrogen phosphate, or the like is added, the residual amount of vinyl acetate tends to decrease as the pH increases, but the acetic acid concentration tends to increase or the acetic acid concentration does not decrease. This is presumed to be because vinyl acetate is hydrolyzed and acetic acid is by-produced as the added amount increases.

In the vinyl acetate emulsion, various additives depending on the use, for example, a filler, a film forming aid, an antioxidant, a tackifier, a coloring agent, an antifoaming agent, a preservative, a fungicide, An antifreezing agent, a rust preventive, a viscosity modifier and the like may be added. Also, a crosslinking agent may be added as necessary,
Further, a water-soluble organic solvent such as methanol, ethanol, isopropanol and the like may be added.

[0025]

According to the present invention, the vinyl acetate emulsion is
Since it contains a water-soluble silicate San'a alkali metal salts, high stability, it can be remarkably reduced vinyl acetate odor and acetic acid odor.

[0026] In the method of the present invention is a simple operation of adding a water-soluble silicate San'a alkali metal salts, can be reduced vinyl acetate odor and acetic acid odor.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to embodiments.

Examples 1 to 4 To 100 parts by weight of a polyvinyl acetate emulsion (containing 40% by weight of polyvinyl acetate as a solid content and 10% by weight of polyvinyl alcohol as a solid content), a 10% by weight aqueous solution of sodium silicate was added. 4.
2 parts by weight (Example 1, 1.05% by weight), 7.6 parts by weight (Example 2, 1.9% by weight), 10.2 parts by weight (Example 3, 2.55% by weight) and 12 0.0 parts by weight (Example 4, 3.0% by weight) was added, and the mixture was stirred uniformly.

Comparative Examples 1-4 Instead of sodium silicate,
It was added to the polyvinyl acetate emulsion in the same manner as in Example 1 except that a 10% by weight aqueous solution of soda ash was used.

Comparative Examples 5-8 Instead of sodium silicate,
It was added to the polyvinyl acetate emulsion in the same manner as in Example 1, except that a 10% by weight aqueous solution of disodium hydrogen phosphate was used.

COMPARATIVE EXAMPLES 9 TO 12 The procedure of Example 1 was repeated, except that a 10% by weight aqueous solution of triethanolamine was used instead of sodium silicate.

The emulsions obtained in the above Examples and Comparative Examples were subjected to gas chromatography to measure the contents of vinyl acetate and acetic acid. The polyvinyl acetate emulsion before adding sodium silicate contained 0.069% by weight of vinyl acetate and 0.20% by weight of acetic acid. The results are shown in the table.

[0033]

[Table 1] As can be seen from the table, the addition of sodium silicate can reduce the residual amounts of vinyl acetate and acetic acid. On the other hand, with soda ash and triethanolamine, a large amount of acetic acid is by-produced as the amount of addition increases, and an acetic acid odor is generated. In addition, disodium hydrogen phosphate has a small effect of reducing the residual amounts of vinyl acetate and acetic acid, and cannot particularly reduce the residual amounts of acetic acid.

──────────────────────────────────────────────────の Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) C08L 31/04 C08K 3/34-3/36 C09D 131/04 C09J 131/04 WPI (DIALOG)

Claims (3)

(57) [Claims] 1. A vinyl acetate polymer in an emulsion
To 100 parts by weight of water-soluble silicate San'a alkali metal salt
Low-odorized vinyl acetate emulsion containing 0.01 to 10 parts by weight . 2. The composition according to claim 1, wherein the proportion of the water-soluble alkali metal silicate is
0.1 to 5 based on 100 parts by weight of vinyl acetate polymer
2. The vinyl acetate emulsion according to claim 1, which is in parts by weight.
N. To 3. The vinyl acetate based emulsion, a water-soluble Ke <br/> Lee San'a alkali metal salts of vinyl acetate-based polymer 100 wt
A method for reducing the odor of a vinyl acetate emulsion by adding 0.01 to 10 parts by weight per part by weight .