JPS5950683B2 - Enkabinirjiyushino Seizouhouhou - Google Patents

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 paste vinyl chloride resin is known, in which the resin is homogenized by a shearing action using a colloid mill or the like, and then heated and polymerized.

Vinyl chloride polymers produced by this method usually have 0
．． The latex is made up of small spherical particles with a size of 0.5 to 1.5 μm. Dry this latex using a known drying device such as a spray dryer to obtain a paste resin. If a plasticizer, stabilizer, etc. are added to this, a stable sol can be obtained. can get.

These are used for various purposes such as rotational molding, spread coating, and foam molding. Sols made from paste resins made by these polymerization methods are characterized by strong thixotropic properties and high yield values. It is.

Paste resins with this characteristic are extremely advantageous in processing methods such as spread coating, but on the other hand, in processing methods such as slush molding and dip molding, the flow of the sol, so-called "drip", is poor and the resulting product is "Sagging" occurs on the surface and inner surface, making it undesirable as a product. In view of these points, the inventors employed a polymerization method that involved homogenization treatment using a monomer-soluble catalyst, and worked diligently to industrially advantageously produce a paste resin that provides a sol with a small yield value. As a result of research, it was discovered 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 uses vinyl chloride or a vinyl monomer mainly composed of vinyl chloride, a catalyst soluble in the monomer, an emulsifier and/or a polymerization stabilizing aid, and a monomer. After homogenization, the remaining water or hot water is added to the mixture and polymerization is carried out, or the mixture is placed in water or hot water and the amount of water is equal to the amount of monomer. It is characterized by polymerization at a ratio of 1.5 or more.

More specifically, in the present invention, the above object is achieved only when the amount of water during homogenization is less than the amount of monomer used in polymerization. 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 achieved even more effectively when the amount of water to be homogenized is less than half the amount of monomer 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.

Normally, on an industrial production scale, the amount of water is 1 to the amount of monomer.
．． 5 to 2.0 times. When the amount is less than this, polymerization stability is poor such as a large amount of scale being generated, workability is not favorable, and a product of constant quality cannot be obtained.
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 ether, polyoxyethylene alkyl ester, polyoxyethylene, propylene block copolymer, etc., can be used in combination with the above anionic activator, and sodium sulfate, dibasic sodium phosphate, etc. Salt may also be used. The amount of these emulsifiers used is 0.3 to 5% by weight based on the monomer.
A range of is preferred. Examples of the polymerization stabilizing aid include cellulose derivative polyvinyl alcohol, higher alcohols such as cetyl alcohol and dodecyl alcohol, and higher fatty acids such as palmitic acid and stearic acid.

These can be used alone or in combination of two or more, and the amount used is preferably 5" or less by weight based on the monomer. As a polymerization initiator, 2,2'-azobis-2,4-dimethylvalerol Azo compounds such as nitrile (ABVN), acyl peroxides such as lauroyl peroxide, and dialkyl peroxydicarbonates such as diisopropyl peroxydicarbonate can be used alone or in combination of two or more types.

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°C 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 hot 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 In a 10 ton capacity stainless steel homogenizer, 2.7 kg of vinyl chloride monomer, 18.99 kg of sodium dodecylbenzenesulfonate, 21.69 kg of cetyl alcohol, 2.
z-azobis-2,4-dimethylvaleronitrile 1.5
After adding 4 g of water in the amount shown in Table 1, the air in the container was sufficiently replaced with nitrogen.

After homogenizing for 1 hour with a high-speed homogenizer at a rotation speed of 3,000 rpm, the homogenized mixture was transferred to a reactor equipped with a stirrer. As shown in Table 1, the reactor contains H2
Add water in advance so that O/Vcl (weight ratio) = 1.6/1. The pressure was kept at HRH9.

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. 100 parts of paste resin, DOP6O parts, Ca-Zn
After 3 parts of the system liquid stabilizer were uniformly mixed and defoamed, the sol viscosity was measured using a BM type viscometer. The results are shown in Table-1. Comparative Example 1 Experiments Nos. 4 and 5 used the homogenization process, and the amount of copolymerization water was the same, and Experiment No. 6 used the homogenization process, where l-12αNcl was 1/1 by weight and polymerization was 1.6/1. Except for this, the experiment was carried out under exactly the same conditions as in Example 1.

The results are shown in Table 2. From the above results, what happens when the H2O/Slcl specific sol viscosity (,) in the homogenization process is less than 1? It can be seen that the value of is less than 1×Yield value 10-2, and the yield value is becoming smaller.

Comparative Example 2 In the experiment of Example 1, Experiment No. 1, the polymerization was carried out without adding water to the polymerization machine in advance, with the ratio of H2O/Vcl2 remaining at 0.8/1.

The contents of the polymerizer after polymerization were almost lumpy, and normal polymerization could not be achieved. Example 2 In the experiment of Example 1, Experiment No. 2, 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.

Claims (1)

[Claims] 1 After mixing vinyl chloride or a vinyl monomer mainly composed of vinyl chloride, a monomer-soluble catalyst, an emulsifier and/or a polymerization stabilizing aid, and water in an amount less than the monomer amount, and homogenizing the mixture. , the mixture is polymerized by adding the remaining water or warm water, or the mixture is placed in water or hot water and the ratio of the amount of water to the amount of monomer is 1.5 or more. A method for producing vinyl chloride resin.