JPH01306406A - Method for producing vinyl chloride polymer - Google Patents

Abstract

PURPOSE:To obtain the subject polymer having excellent quality in high productivity by introducing aqueous-emulsified polymerization initiator into polymerization vessel, heating feeding piping and feeding port from outside and preventing generation of polymer scale. CONSTITUTION:In polymerizing vinyl chloride or vinyl monomer containing vinyl chloride in an aqueous medium, a polymerization initiator is aqueous- emulsified and introduced into polymerization vessel, then feeding piping connecting to inside of said polymerization vessel and feeding port of said polymerization vessel are heated (preferably >=80 deg.C, especially 100 deg.C) from outside, then remained polymerization initiator is degraded and effectively removed, thus generation of polymer scale is prevented. By said method, a work removing polymer scale is unnecessary and a production in high productivity. Furthermore, a polymer having excellent quality is obtained because of using no organic solvent.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for producing a vinyl chloride polymer, and in particular to a method for producing a vinyl chloride polymer that can produce a high quality vinyl chloride polymer with high productivity. The present invention relates to a method for producing a polymer.

[Conventional technology]

During the production of vinyl chloride polymers, after the polymerization initiator is supplied into the polymerization vessel through the charging piping and the charging port of the polymerization vessel, the polymerization initiator adheres to and remains on the piping and the charging port, and the monomer content is lost during polymerization. May react with bodies to form polymer scale.

Therefore, as a method to remove the polymerization initiator that adheres to and remains on the piping and charging port and prevent the formation of polymer scale, there is a method of cleaning the piping and charging port with an organic solvent, and then closing the charging port after cleaning. Methods have been proposed to prevent the invasion of monomers. However, in these methods, the organic solvent used for cleaning remains in the polymer product, causing a bad odor during molding.

In order to solve these problems, a method has been proposed in which the polymerization initiator is prepared as an aqueous emulsion and no organic solvent is used for cleaning.

[Problem to be solved by the invention]

However, even in the above method using a polymerization initiator made into an aqueous emulsion, the polymerization initiator may still adhere to or remain in piping and charging ports, and if polymerization is carried out for a long period of time, polymer scale will be generated. There was a problem.

Therefore, the purpose of the present invention is to effectively remove the polymerization initiator remaining in the pipes etc. after charging, prevent the formation of polymer scale, and furthermore, because it does not use organic solvents, it can produce high quality products. The object of the present invention is to provide a method for producing a vinyl chloride polymer that can be polymerized.

[Means to solve the problem]

The present invention solves the above problems in a method for producing a vinyl chloride polymer in which vinyl chloride or a vinyl monomer containing vinyl chloride is polymerized in an aqueous medium.
Provided is a method for producing a vinyl chloride polymer, characterized in that after a polymerization initiator is made into an aqueous emulsion and introduced into a polymerization vessel, a charging pipe leading into the polymerization vessel and a charging port of the polymerization vessel are heated from the outside. It is something to do.

In the method of the present invention, the charging pipes leading into the polymerization vessel and the charging port of the polymerization vessel mainly refer to the pipes for supplying the polymerization initiator into the polymerization vessel and the initiator charging port of the polymerization vessel to which the pipes are connected. However, this also includes cases in which other piping and charging ports, such as monomer or other additive supply piping and charging ports, are externally heated as necessary.

In the method of the present invention, after aqueous emulsified polymerization initiator is charged, the piping and the charging port are heated from the outside to decompose and remove the polymerization initiator that adheres to and remains on the piping and the charging port. Methods for heating piping and charging ports from the outside include heating jackets installed around the outside of piping and charging ports, or steam, hot water, or heating between the outer and inner pipes of piping with a double pipe structure. This can be done by heating through a heated fluid such as a heated solvent or oil. When using steam, steam used or generated in other processes within the factory can be used.

The temperature of the heat σ may be any temperature at which the polymerization initiator used decomposes, and is usually preferably 80°C or higher, more preferably 100°C or higher, and heating at 100°C or higher will destroy the polymerization initiator. can be rapidly decomposed.

The polymerization initiator used in the form of an aqueous emulsion in the present invention is not particularly limited, and includes those used in the production of conventional vinyl chloride polymers, such as diisopropyl peroxydicarbonate and di-2-ethylhexyl peroxydicarbonate. bar carbonate compounds such as , jetoxyethyl peroxydicarbonate; Ester compound; acetylcyclohexylsulfonyl peroxide,
Peroxides such as 2,4.4-trimethylbenzene-2-peroxyphenoxyacetate, 3°5.5-)limethylhexanoyl peroxide; azobis-2,4-dimethylvaleronitrile, azobis(4-methoxy -2,
(4-dimethylvaleronitrile); potassium persulfate, ammonium persulfate, hydrogen peroxide, and the like. These can be used alone or in combination of two or more.

In the present invention, the polymerization initiator is made into an aqueous emulsion using a dispersant, and the viscosity is usually adjusted before being charged into a polymerization vessel to initiate polymerization.

The above-mentioned dispersant may be one used in general vinyl chloride suspension polymerization, emulsion polymerization, etc., such as partially saponified polyvinyl alcohol, cellulose ethers, water-soluble starch ethers, polyacrylic acid, polyoxyethylene sorbitan, etc. Examples include monolaurate and the like.

The method of the present invention can be applied to any conventionally known polymerization of vinyl chloride or vinyl monomer mixtures containing vinyl chloride. The polymerization type is not limited either, and examples thereof include suspension polymerization and emulsion polymerization.

Examples of vinyl monomers other than vinyl chloride include EVA, ethylene, propylene, 1-butene, 1-bentene, and 1-bentene.
hexene, 1-heptene, 1-octene, 1-nonene,
α-olefins such as 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, acrylic acid and its esters, methacrylic acid and its esters, maleic acid and its esters, vinyl acetate, propion Vinyl compounds such as acid vinyl and alkyl vinyl ether; maleic anhydride: acrylonitrile; styrene; vinylidene chloride; other monomers copolymerizable with vinyl chloride, and mixtures thereof.

When a dispersant is used in this polymerization, the dispersant used is not particularly limited, and any conventionally commonly used dispersant may be used. Water-soluble cellulose ethers such as methylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose; partially saponified polyvinyl alcohol; acrylic acid polymers; water-soluble polymers such as gelatin; sorbitan monolaurate, sorbitan triolate, glycerin tristearate, ethylene oxide propylene Examples include oil-soluble emulsifiers such as oxide block copolymers; water-soluble emulsifiers such as polyoxyethylene sorbitan monolaurate, polyoxyethylene glycerin oleate, and sodium laurate.

These can be used alone or in combination of two or more.

Other conditions for polymerization in the method of the present invention, such as the method of charging an aqueous medium, vinyl chloride and other vinyl monomers, and a dispersant to the polymerization vessel, may be carried out in the same manner as conventional methods and are not particularly limited. .

Further, the polymerization conditions such as the charging ratio and polymerization temperature are also the same.

Furthermore, if necessary, polymerization modifiers, chain transfer agents, pH adjusters, gelling improvers, antistatic agents, scale inhibitors, etc. that are commonly used in the production of vinyl chloride polymers may be added. be.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

Example 1 980 kg of deionized water, 382 g of partially saponified polyvinyl alcohol, and 143 g of water-soluble methyl cellulose were charged into a stainless steel polymerization vessel having an internal volume of 2000 ffi, and after the inside of the polymerization vessel was degassed, 700 kg of vinyl chloride was charged. Next, 580 g of a 50% aqueous emulsion of di-2-ethylhexyl peroxydicarbonate was introduced into the polymerization reactor using a metering pump, and a heating jacket was placed outside the piping and charging port through which the polymerization initiator passed. The piping and charging port were heated to 100°C by passing steam (120°C) through them for 3 minutes.

While stirring the inside of the polymerization vessel, the temperature was raised to 60°C to start polymerization, and the internal pressure of the polymerization vessel was 6.0 kg/c++! Polymerization is stopped when the temperature decreases to , and unreacted monomers are collected.
After dehydration and drying, a vinyl chloride polymer was obtained.

After polymerization, disassemble the polymerization initiator charging piping and charging port, observe the state of polymer scale adhesion at these locations, evaluate using the following criteria, and evaluate the amount of residual organic solvent in the polymer as shown below. It was measured using the method. The results are shown in Table 1.

(Evaluation method of scale adhesion state) A---No scale adhesion.

B---A small amount of scale was attached.

A large amount of C-.-scale adhered and blocked the feed port.

(Method for measuring the amount of residual organic solvent) 5 g of the obtained polymer was placed in a vial, heated at 130°C for 30 minutes, and the gas phase of the vial was analyzed by gas chromatography. Amounts are given in ppm.

Examples 2 to 3 After repeating the same polymerization as in Example 1 100 times (Example 2) or 1000 times (Example 3) on each side, the adhesion state of the polymer scale was similarly observed and the obtained The amount of organic solvent remaining in the polymer was measured.

The results are shown in Table 1.

Comparative Examples 1-2 Toluene 300 without heating the preparation piping and the preparation port
cc (Comparative Example 1) or n-hexane 300 cc (
After repeating the same polymerization as in Example 1 100 times, except for washing in Comparative Example 2), the adhesion state of the polymer scale was similarly observed and the amount of residual organic solvent in the obtained polymer was measured. The results are shown in Table 1.

Comparative Example 3 Polymerization was carried out in the same manner as in Example 1, except that the charging piping and charging port were not heated or washed, and the state of adhesion of polymer scale was similarly observed and the resultant polymer was The amount of residual organic solvent was measured. The results are shown in Table 1.

Table 1 [Effects of the Invention] The method for producing vinyl chloride polymers of the present invention can prevent the formation of polymer scale, so there is no need to remove the polymer scale, and it is possible to produce vinyl chloride polymers with high productivity. Polymers can be produced. Moreover, since there is no organic solvent remaining in the product polymer, it is possible to obtain a vinyl chloride polymer of excellent quality.

Claims (1)

[Claims] In a method for producing a vinyl chloride polymer in which vinyl chloride or a vinyl monomer containing vinyl chloride is polymerized in an aqueous medium, a polymerization initiator is turned into an aqueous emulsion and introduced into the polymerization vessel, and then the preparation is conducted into the polymerization vessel. A method for producing a vinyl chloride polymer, which comprises heating the pipes and the charging port of a polymerization vessel from the outside.