JPS5823808A - Preparation of vinyl chloride resin - Google Patents

Abstract

PURPOSE:To prepare the titled resin capable of giving a paste having low yield value of sol when used as a plastisol, etc., by mixing and homogenizing vinyl chloride, etc. with a catalyst, an emulsifier, a polymerization stabilizing assistant, and a specific amount of water, and carrying out the polymerization of the monomer. CONSTITUTION:In the polymerization of vinyl chloride or a vinyl monomers composed mainly of vinyl chloride, the monomer is mixed and homogenized with (A) 0.002-0.2wt% (based on the monomer) catalyst soluble in the monomer (e.g. 2,2'-azobis-2,4-dimethylvaleronitrile), (B) 0.3-5% emulsifier (e.g. dodecylbenzenesulfonic acid sodium salt) and/or <=5% polymerization stabilizing assistant (e.g. cetyl alcohol), and (C) <100%, preferably <=50% water, and the mixture is polymerized at 30-70 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a vinyl chloride polymer for paste, and more specifically to an industrial method for producing a vinyl chloride polymer that provides a paste with a small sol yield value when used as a plastisol or organosol. It relates to an advantageous manufacturing method.

A dispersion of vinyl chloride or a monomer mainly composed of vinyl chloride is processed using a monomer-soluble catalyst, such as a high-speed pump,
A method for producing a vinyl chloride resin for paste is known, in which the resin is homogenized by a shearing action using a colloid mill or the like, and then heated and polymerized. The vinyl chloride polymer produced by this method usually consists of small spherical particles of 0.05 to 1.5μ,
This latex is dried using a known drying device such as a spray dryer to obtain a base resin, and by adding a plasticizer, stabilizer, etc. to this, a stable sol can be obtained.

These are applied to various applications such as rotational molding, spread coating, and foam molding, but the sols made from paste resins made by these polymerization methods are characterized by strong thixotropic properties and high yield values. It is. Base resin with this characteristic is extremely advantageous for processing methods such as spread coating, but on the other hand, when processing methods such as slush molding and dip molding, the flow of sol
The so-called "drip" is poor, and "sagging" occurs on the surface and inner surface of the obtained product, making it undesirable as a product.

In view of these points, the inventors adopted a polymerization method that involved homogenization treatment using a monomer-soluble catalyst, and conducted intensive research to industrially advantageously produce a base resin that provides a sol with a small yield value. As a result, it was found that the desired product could be obtained by improving the above polymerization method.

That is, in producing a vinyl chloride resin for paste, the present invention involves adding a catalyst, an emulsifier, and/or a polymerization stabilizing agent soluble in the monomer before polymerizing vinyl chloride or a vinyl monomer mainly composed of vinyl chloride. The gist of this method is to mix water in an amount less than the amount of monomer used and homogenize it with the monomer, and when the amount of water during homogenization is less than the amount of monomer used in polymerization. Only then will the above objective be achieved.

Thus, in the conventional method, the entire amount of water used for polymerization was included in the homogenization step, or the amount of water in the homogenization step was in excess of the amount of monomer, whereas in the present invention, the amount of water used in the homogenization step was in excess of the amount of monomer. A portion of the monomer is used in the homogenization step and the amount must be less than the amount of monomer. More preferably, the above object is more effectively achieved when the amount of water to be homogenized is less than half of the amount of water to be homogenized.

From the standpoint of polymerization stability, the larger the amount of water used in polymerization, the better; however, from the standpoint of productivity, the lower the amount, the better.

The monomer used in this invention is vinyl chloride, and monoolefin monomers copolymerizable with it, such as vinyl acetate,
Vinylidene chloride, acrylonitrile, acrylic esters, maleic acid, etc., and mixed monomers thereof can also be used.

As the emulsifier, common anionic emulsifiers such as sodium alkyl sulfate, sodium alkylbenzenesulfonate, and sodium dioctyl sulfosuccinate are used. Nonionic emulsifiers, such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, polyoxyethylene, and propylene block copolymers, can be used in combination with the above anionic activators, and salts such as sodium sulfate and sodium diphosphate can also be used. May be used together. The amount of these emulsifiers used is preferably 0.3 to 5% by weight based on the monomer.

Preferred polymerization stabilizing aids include cellulose derivatives, polyvinyl alcohol, and higher alcohols such as heptyl alcohol and dodecyl alcohol, palmitic acid,
These include higher fatty acids such as stearic acid. These are q
It can be used alone or in combination, and the amount used is t.
It is preferably 5% by weight or less based on the li mass.

As a polymerization initiator, an azo compound such as 2,2-azobis-2,4-dimethylvaleronitrile (ABVN), an acyl peroxide such as lauroyl peroxide,
Dialkyl peroxydicarbonates such as diisopropyl peroxydicarbonate can be used alone or in combination of two or more. The amount used is determined by the polymerization temperature and the type of catalyst, but is usually in the range of 0.02 to 0.2% by weight based on the monomer.

The polymerization temperature is usually determined from 30 to 70°C depending on the desired degree of polymerization.

If the method of the present invention is adopted, the amount of liquid used in the homogenization process is small, so the equipment for the homogenization process can be small, and the homogenization time can be shortened. Furthermore, if hot water is used after the homogenization step, the time required to raise the temperature can be shortened, which greatly contributes to productivity. On the other hand, it is not necessary to introduce water or warm water into the homogenization solution before the start of polymerization, and it is possible to introduce water or hot water into the homogenization solution during the polymerization as long as the stability of the polymerization state of the system is maintained.

The present invention will be explained below based on Examples.

Example 1 1O1! In a stainless steel homogenizer with a capacity of 2.7 to 9.9 parts vinyl chloride monomer, 18.99 parts of dodecylbenzenesulfonic acid sorter, and 21.69 parts of cetyl alcohol.
2'-Azobis-2,4-dimethylvaleronitrile 1.
After adding 54S' and water in the amount shown in Table 1, the air in the container was replaced with nitrogen. High speed homogenizer rotation 3
After homogenizing for 1 hour at 8000 rpm, the homogenized mixture was transferred to a reactor with a stirrer.

As shown in Table 1, water was added to the reactor in advance so that H20/VCJ (weight ratio) = 1.671, and the pressure was increased to 80 mmH.
The pressure was set to 7. Polymerization was carried out at a polymerization temperature of 45° C. for 15 hours. The obtained latex was dried with a spray dryer to obtain a paste resin.

After uniformly mixing 100 parts of base resin, 60 parts of DOP, and 3 parts of Ca-Zn liquid stabilizer, defoaming was performed, and the sol viscosity was measured using a BM type viscometer. The results are shown in Table-1.

Comparative Example 1 Experiment Nos. 4 and 5 use the same amount of water in the homogenization step and polymerization, and Experiment No. 6 uses H20/VC1! in the homogenization step. Polymerization was carried out under the same conditions as in Example 1, except that the polymerization ratio was 1/l by weight at 1.6/1. The results are shown in Table-1.

Example 2 In the experiment No. 2 of Example 1, instead of putting water into the polymerization machine in advance, the homogenized liquid was put into the polymerization machine and then a predetermined amount of water was pressurized. Table 1 shows the results as experiment number 7.
It was shown to.

From the results in Table 1, H20/VC/ru in the homogenization step.

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Claims (2)

[Claims] (1) Before polymerizing vinyl chloride or a vinyl monomer mainly composed of vinyl chloride, add a soluble catalyst, emulsifier and/or polymerization stabilizing aid to the monomer, and water in an amount less than the amount of monomer used. A method for producing vinyl chloride resin, which comprises mixing it with a monomer and homogenizing it. (2) The manufacturing method according to claim 1, wherein the amount of water used for homogenization is less than half the amount of monomer.