JPS58201837A - Stabilization of polyvinyl acetate emulsion - Google Patents

Abstract

PURPOSE:To stabilize the titled emulsion, without causing the viscosity increase with time, by adding a sulfite, thiosulfate, bisulfite, metabisulfite, etc. to a vinyl acetate emulsion containing acetoacetylated polyvinyl alcohol. CONSTITUTION:The stabilization of a vinyl acetate emulsion (an emulsion obtained by the emulsion polymerization of vinyl acetate or vinyl acetate and other monomer such as acrylic acid ester) containing an acetoacetylated polyvinyl alcohol (preferably having an average polymerization degree of PVA of 200- 3,000 average saponification degree of 30-100mol% and an acetoacetylation degree of 0.05-15mol%) is carried out by adding a stabilizer comprising one or more materials selected from sodium salt, potassium salt, etc. of sulfurous acid, thiosulfuric acid, bisulfuric acid, and metabisulfurouc acid, and stirring the mixture to obtain a homogeneous emulsion. The amount of the stabilizer is preferably 0.2-4wt% based on the solid content of the emulsion.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for stabilizing a polyvinyl acetate emulsion containing acetoacetylated polyvinyl alcohol (hereinafter abbreviated as AA-PVA).

More specifically, AA
The present invention relates to a method for stabilizing an emulsion in which PTA is added and mixed.

Polyvinyl acetate-based synthetic resin emulsions have a wide range of uses, including adhesives, paints, fiber and textile processing, paper and leather processing, binders for various materials, and admixtures for cement mortar. Some of these uses include, for example, adhesives, paints, and coatings on textiles, where synthetic resin emulsions with high viscosity (and moderate structural viscosity) have excellent workability, mechanical suitability, finish quality, and adhesion. It is often requested because it shows a positive effect.

9 km, high viscosity emulsions can be made by emulsion polymerization using a water-soluble sieve molecule-retaining colloid as an emulsifier, or by adding water-soluble bacterial molecules to a low-viscosity emulsion to thicken it, but both methods are suitable for emulsions. The disadvantage is that the performance and water resistance are reduced.

As a method for producing a high viscosity emulsion that overcomes these drawbacks, a method using AA-PVA as an emulsifier or binder has been developed. AA PVA is made by acetoacetylating a part of polyvinyl alcohol (abbreviated as AA), and emulsions made by emulsion polymerization using this as an emulsifier, or emulsions made by adding it later to thicken it, are water resistant. is extremely excellent. however,
The emulsion thickened by this AA-PVA has the disadvantage that the viscosity increases by L over time and becomes pudding-like in a short period of time, which hinders its practical use.

As a result of various studies on this issue, the inventors found that
The present invention was completed based on the discovery that the viscosity of an emulsion can be prevented from increasing over time by adding a variety of salts.

That is, the present invention provides acetoacetylated polyvinyl) L,
Adding one or more selected from sulfite, thiosulfate, bisulfite, and metabisulfite to the vinyl emulsion containing 7/L/ml This is a characteristic feature of stabilizing polyvinyl acetate emulsions.

According to the present invention, a polyvinyl acetate emulsion thickened using AA PvA as an emulsifier or thickener,
Just by adding and mixing one selected from sulfite, thiosulfate, bisulfite, and metabisulfite, the viscosity does not increase over time and remains pudding-like even when stored. A unique effect is produced that cannot be predicted.

The emulsion to be subjected to the stabilization method of the present invention is AA
These are polyvinyl acetate emulsions that are emulsion-polymerized using chemically modified PTA as an emulsifier, or polyvinyl acetate emulsions that are later swollen with AA modified FVA. Of course, emulsions containing surfactants are also included.

AA PvA is polyvinyl alcohol m H'B
It is a modified polyvinyl alcohol obtained by reacting diketene, acetoacetic acid, acetoacetic ester, etc. The AA-PVA used is PVA, +7) average degree of polymerization 200-3000, average saponification 1v30::! -100 mol% and AA degree of 0.05-15 mol% are suitable. As the AA PVA used as an emulsifier, P
VA average polymerization degree 500-2600, average saponification degree 85
-99 mol% and AA degree of 0.05-15 mol% are preferable, and the amount used as an emulsifier may generally be in the range of 2-20 mole % based on the whole monocitrus fruit. In addition, as the AA PvA used for post-expansion, the average degree of polymerization of PTA is 200 to 3.
000, average saponification degree 30-100 mol%, A, A-based F
O is preferably 11 to 15 mol %, and the amount added is usually 2 to 20 w % based on the solid content of the emulsion.

Examples of emulsions containing AA FVA include vinyl acetate or vinyl acetate, acrylic esters, methacrylic esters, ethylene, vinyl esters of branched 71N fatty acids having 10 carbon atoms, styrene, vinyl chloride, acrylonitrile, maleic esters, and acrylic esters. acids, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid,
Examples include emulsions obtained by emulsion polymerization of one or more monomers selected from phthalic acid, N-methylol acrylamide, and the like.

In the method of the present invention, the rules used to stabilize the viscosity of polyvinyl acetate emulsions containing AA-PVA (stabilizers include diuric sulfuric acid, thiosulfuric acid, bisulfite,
One or more selected from sodium salt, potassium salt, ammonium salt, or amine salt of metasulfite.

The amount used is 0.2 to 4 parts per 100 parts by weight of the solid content of the polyvinyl acetate emulsion containing AA ffA.
Severe case section is appropriate. The method for using the stabilizer is to dissolve the stabilizer in an appropriate amount of water, and the concentration is not particularly heavy, but it is preferably about 5 to 50% because it is easy to handle. A predetermined amount of the obtained aqueous stabilizer solution may be added to the emulsion and stirred to uniformly mix.

Next, the present invention will be explained by giving Examples and Comparison 4 [9 examples].
The invention is not limited only to these examples.

Example 1 Polymerization degree 1100, saponification degree 99 mol%, AA [5,0
All single paulownia bodies using mol% of AA-PVA as a protective colloid.
On the other hand, to 100 layers of polyvinyl acetate emulsion with a concentration of 40% obtained by emulsion polymerization of vinyl acetate using 10% vinyl acetate, add 2 portions of a 40% aqueous solution of sodium bisulfite while stirring. and mixed uniformly. The resulting emulsion was tested for storage stability and the results were reported @1
Shown in the table.

Examples 2 to 7 Example 1 (in which the resin composition, type and amount of AA-PVA, type and amount of stabilizer, and emulsion concentration were changed as shown in Table 1) Emulsions were prepared in the same manner and tested for storage stability.The results are shown in Table 1.

Example Day Emulsion polymerization using surfactant polyoxyethylene nonylphenol ether, concentration 40%, viscosity 7500 c
To 100 parts of polyvinyl acetate emulsion of P, 1 AA PVA with a polymerization of 1'l'1700, a degree of saponification of 99 mol%, and a degree of AA of 5.4 mol% was stirred as a powder. Add the mixture while heating to 60-80°0 and bring to 270°C.
Thickened to 0 cP. Solid content of this emulsion: 100
2 parts by weight of a solid sodium bisulfite aqueous solution was added to the heavy sample portion, and the mixture was uniformly mixed. The resulting emulsion was tested for storage stability and the results are shown in Table 1.

Comparative Example 1 An emulsion was prepared in the same manner as in Example 1, except that the stabilizer sodium bisulfite was not added. The results obtained are shown in Table 1.

Comparative Example 2 In Example 3, instead of the added stabilizer sodium bisulfite, # and sodium hydroxide were used.
An emulsion was prepared in the same manner as in Example 6 and tested for release I# stability. The results obtained are shown in Table 1.

Comparative Example 6 In Example 8, the stabilizer taiII! An emulsion was prepared in the same manner as in Example 8, except that sodium sulfate was not added, and the storage stability was tested. The results obtained are shown in Table 1.

Procedural amendment (spontaneous) Kazuo Wakasugi, Commissioner of the Patent Office 1 Indication of the case 1982 Patent Application No. 85462 2 Name of the invention Method for stabilizing polyvinyl acetate emuldimine 3 Relationship with the person making the amendment Patent application Subject of person 5 amendment (1) Contents of amendment in column 6 of “Detailed explanation of the invention” in the specification (1) “2700 cPJ to r270” in page 7 line 18 of the specification
Correct it to 00cpJ.

(2) [50:50J on the resin composition side of Example No. 4 in Table 1 on page 9 of the specification is corrected to 60:40J.

that's all

Claims (1)

[Claims] 1. A polyvinyl acetate characterized by adding one or more selected from sulfite, thiosulfate, bisulfite, and metabisulfite to a polyvinyl acetate emulsion containing acetoacetylated polyvinyl alcohol. Method for stabilizing system emulsions.