JPH0493301A - Dispersing agent and dispersion stabilizer for suspension polymerization of vinyl monomer - Google Patents

Abstract

PURPOSE:To obtain vinyl chloride resin particles having nearly the same sharp particle diameter distribution and excellent porousness and uniformity by mixing a specified polyvinyl ester polymer with a PVA polymer. CONSTITUTION:10-90wt.% dispersing agent comprising a polyvinyl ester polymer of a degree of saponification of 55mol.% or below and a degree of polymerization of 1000-3500 is mixed with 90-10wt.% PVA polymer of a degree of saponification of 65-95mol% and a degree of polymerization of 300-3500 to obtain a dispersion stabilizer. A mixture comprising a vinyl chloride monomer and optionally a comonomer (e.g. vinyl acetate) is suspension-polymerized at 30-100 deg.C in an aqueous medium in the presence of 0.01-1wt.% above dispersion stabilizer and an oil-soluble catalyst (e.g. benzoyl peroxide).

Description

Detailed Description of the Invention The present invention A is a method of suspending a monomer mixture containing vinyl monomers, particularly vinyl chloride, or other monomers copolymerizable with vinyl chloride (hereinafter collectively referred to as vinyl chloride monomers) in an aqueous medium. Concerning dispersion aids and dispersion stabilizers used during polymerization.

B, 'O' When producing vinyl chloride resin industrially, a suspension polymerization method is used in which vinyl chloride monomers are dispersed in an aqueous medium in the presence of a dispersion stabilizer and polymerized using an oil-soluble catalyst. Wide
It has been implemented. In general, the factors that control the quality of the resin include the polymerization rate, water monomer ratio, polymerization temperature, type and amount of catalyst, type of polymerization tank, stirring speed, and type and amount of dispersion stabilizer, among others. It is known that the effect of the type of stabilizer is very large.

The performance required of a dispersion stabilizer for suspension polymerization of vinyl chloride monomers is (1) to exhibit high dispersion power even when used in a small amount, and to make the particle size distribution of the resulting vinyl chloride polymer particles as uniform as possible; (ii) to increase the absorption rate of the plasticizer to facilitate processability and to facilitate the removal of vinyl chloride monomer remaining in the polymer particles; (iii) Making polymer particles with a large filling specific gravity; (1-) Preventing scale from forming in polymerization tanks, etc. and (v) high thermal stability of the obtained polymer particles.

Conventionally, cellulose derivatives such as methyl cellulose and carboxin methyl cellulose, partially saponified polyvinyl alcohol (hereinafter abbreviated as PVA), etc. have been used alone or in combination as dispersion stabilizers for suspension polymerization of vinyl chloride monomers. There is. However, these have the drawbacks of low ability to make vinyl chloride polymer particles porous, slow absorption rate of plasticizers, and difficulty in removing residual vinyl chloride monomers. In addition, in order to improve these drawbacks, the degree of saponification is 60 mol% or less and the degree of polymerization is 1.
oo~900 oil-soluble polyvinyl ester polymer (
A method has been proposed in which PVAc (hereinafter abbreviated as PVAc) is used in combination with a conventionally known dispersion stabilizer. However, in this case, although porous vinyl chloride resin can be obtained, there is a fatal drawback that the filling specific gravity tends to decrease.
Furthermore, the scale adhesion to the polymerization tank and the thermal safety of the polymer particles were not satisfactory.

Problems to be Solved by C1 The object of the present invention is to provide a dispersion aid and a dispersion stabilizer for the suspension polymerization of hinyl monomers, which do not have any of the above-mentioned problems.

D
) As a result of intensive research to develop dispersion aids and dispersion stabilizers that simultaneously satisfy the performance requirements of
When using a dispersion aid consisting of PVAc (A) in 01), it has good reproducibility, almost the same particle size distribution, sharp particle size distribution, and porous and uniform particles. It has been discovered that the present invention satisfies all of the above-mentioned performances (1) to (v), such as excellent performance, high filling specific gravity, no scale adhesion to the polymerization tank, and good thermal stability of the polymer particles. I have finally completed the .

The degree of saponification of PVA (:(A:), which is the dispersion aid of the present invention) is 55 mol% or less, preferably 15 to 55 mol%, more preferably 25 to 45 mol%, and the degree of polymerization is 100 mol%.
0-3500. Preferably it is 1000-2500.

The degree of saponification of PVA (B) used in the dispersion stabilizer of the present invention is 6o to 95 mol%, and the degree of polymerization is 3f)l) to
It is 3500. There is no particular restriction on the weight-based compounding ratio of component (A) and component (B), but (^)/(B)
is preferably 10/90 to 90/10. (A)/
If (B) is less than 10/90, it may be difficult to obtain porous particles;
If it exceeds 10, it may be difficult to obtain particles with a Noyab particle size distribution and a large packing specific gravity. Also P V
If the degree of saponification and degree of polymerization of A c (A) and P V A (B) is outside the above-mentioned range, particles that are porous, have a sharp particle size distribution, and have a large packing specific gravity cannot be obtained.

In the dispersion stabilizer of the present invention, there are no restrictions on the use of conventionally known dispersants and/or surfactants as the third component, as long as the effects of the present invention are not impaired. Examples include cellulose derivatives, saponification degree 5
Low saponification degree P of 0 mol% or less and degree of polymerization less than 1000
Examples include VA c, PVA having a cation, anion, or nonionic group in the side chain, PVA having an ionic group at the end, and a nonionic surfactant.

The dispersion stabilizer of the present invention has a 0.0.
0.01 to 1% by weight, preferably 0.01 to 0.05% by weight.

4% The catalyst used in the circumpolymerization may be any oil-soluble catalyst, such as silver oxide, lauroyl peroxide, diisopropyl chloride carbonate, 2.2 azoiso Butyronitrile, 2,2'-azohis-2,4-trimethylvaleronitrile or mixtures thereof are used.

The polymerization temperature is selected from a range of about 30 to 100°C.

Examples of monomers that can be copolymerized with vinyl chloride include vinylidene halide, vinyl ether, vinyl acetate, acrylic acid, methacrylic acid and their esters, maleic acid and its anhydride, itaconic acid, styrene, and the like.

The present invention has been described in detail above, and particularly preferred embodiments of the present invention are as follows.

(a) Weight-based compounding ratio of component (^) and component (B) (
The dispersion stabilizer according to claim 2, wherein A)/(B) is 10/90 to 90/10.

(b) The dispersion stabilizer according to claim 1 or 2, wherein the polyvinyl ester polymer (A) has a saponification degree of 15 to 55 mol% and a polymerization degree of 1000 to 2500.

-LLL Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these examples in any way. In the following examples, "1-%" and "part" mean by weight unless otherwise specified.

Examples 1 to 6 and Comparative Examples 1 to 2 150 parts of deionized water, various dispersion stabilizers shown in Table 1, and G-2 were placed in an IOOC glass-lined autoclave.
- Charge 02 parts of quinolver oxydicarbonate to ethyl, degas the inside of the autoclave to remove oxygen until 50 parts ml (g), and then add 100 parts of vinyl chloride monomer
The polymerization was carried out by raising the temperature to 57° C. while stirring at a rotation speed of 60 rpm.

At the start of polymerization, the pressure inside the autoclave was 8.0 kg/c.
m”G, but 7 hours after the start of polymerization, it was 3.5 kg/c.
m''G, the polymerization was stopped at this point, unreacted vinyl chloride monomer was purged, and the contents were taken out and dehydrated and dried.

The polymerization yield of vinyl chloride resin is 85%, and the average degree of polymerization is 1.
It was 050.

The performance of the obtained vinyl chloride resin is shown in the second section.

Margin below (1) Particle size distribution Measured by dry sieve analysis using a wire mesh based on Tyler mesh.

(2) Filling specific gravity JIS K 6721-195
9.

(3) Uniformity of particle porosity/vinyl chloride resin 100 parts,
A mixture of 50 parts of DOP, 1 part of dibutyltin maleate, 1 part of cetyl alcohol, 025 parts of titanium white, and 01 part of carbon black was kneaded with a roll at 150°C for a predetermined time,
Create a sheet with a thickness of 02 and let light pass through it.
The number of Fuitunyu eyes contained in the sort per 00 cm2 was counted. If the porosity disappears within a short period of time, it indicates that the particle porosity is uniform.

(4) Plasticizer absorption - Using a planetary mixer connected to a plastograph, put 100 parts of vinyl chloride resin and 50 parts of dioctyl phthalate into a container kept at 80°C, and knead every hour while stirring. Record the torque and display the crosstalk time at the point where the kneading torque decreased.

(5) Residual Salt Himotsumer - A certain amount of vinyl chloride resin was dissolved in tetrahydrofuran, and the vinyl chloride monomer content in the vinyl chloride resin was determined by gas chromatography.

(6) Coloring property test: 100 parts of vinyl chloride resin, 25 parts of dibutyltin maleate, and 80 parts of dioctyl phthalate as a plasticizer were mixed, kneaded for 10 minutes on a roll at 160°C, and a sort of Lmm thickness was taken out. The degree of coloration of the sort was visually observed.

As is clear from the above examples, when a vinyl compound is suspension polymerized using a dispersion stabilizer consisting of a dispersion aid of the present invention, almost the same particle size distribution is obtained with good reproducibility. It has extremely high industrial value, as it has a sharp particle size distribution, each particle is porous, and has excellent uniformity, and it also has a large filling specific gravity, and it is possible to obtain vinyl chloride resin particles with no scale or other adhesion. It is.

Claims (2)

[Claims] (1) Saponification degree 55 mol% or less, polymerization degree 1000-35
A dispersion aid for suspension polymerization of a vinyl monomer consisting of a polyvinyl ester polymer (A) of No. 00. (2) The polyvinyl ester polymer (A
) and saponification degree 65-95 mol%, polymerization degree 300-3
A dispersion stabilizer for suspension polymerization of vinyl compounds consisting of a polyvinyl alcohol polymer (B) of 500%.