JPH01292002A - Production of vinyl chloride polymer - Google Patents

Abstract

PURPOSE:To prevent the production of polymer scales to provide a high quality polymer in a high yield, by introducing a polymerization initiator into a polymerizer and subsequently heating a charge piping and a charge opening from the outsides thereof. CONSTITUTION:When vinyl chloride or a vinylic monomer (e.g., ethylene or 1-butene) containing the vinyl chloride is polymerized in an aqueous medium, a polymerization initiator (e.g., diisopropylperoxydicarbonate or 2,2,4- trimethylpentyl-2-peroxyphenoxyacetate) is introduced into a polymerizer and subsequently a charge piping communicating with the polymerizer and a charge opening of the polymerizer are heated to a temperature of preferably >=100 deg.C from the outsides thereof to decompose the polymerization initiator adhered to or remained in the charge piping and the charge opening, thereby preventing the production of polymer scales to provide a high quality polymer.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a method for producing a vinyl chloride polymer, and in particular, a method for producing a vinyl chloride polymer with high productivity. The present invention relates to a method for producing a vinyl 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. When this polymer scale grows, it clogs the piping or the feed port, so the grown polymer scale must be removed.

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.

[Problem to be solved by the invention]

However, in the former method of cleaning with an organic solvent, a large amount of organic solvent is required to completely remove the polymerization initiator that adheres to and remains on the piping and charging port. It remains in the water and causes quality deterioration and bad odor during molding.

As a result, there are restrictions on the amount of organic solvent used, and sufficient cleaning cannot be performed, resulting in some residual polymerization initiator, resulting in the formation of polymer scale if polymerization is carried out over a long period of time. . Furthermore, even if the latter method is used to close the charging port, the monomer will enter the pipe through the gap in the closed charging port, so there is a problem in that the formation of polymer scale cannot be sufficiently prevented.

Therefore, the purpose of the present invention is to prevent the formation of polymer scale, thereby achieving high productivity, and since no organic solvent is used, it is possible to reduce residual agitation of solvent in the obtained polymer, thereby achieving high quality. An object of the present invention is to provide a method for producing a vinyl chloride polymer, which can yield a product polymer of .

[Means to solve the problem]

The present invention solves the problem described in -F in a method for producing a vinyl chloride polymer, in which vinyl chloride or a single vinyl-based polymer containing vinyl chloride is polymerized in an aqueous medium, in which a polymerization initiator is added to the polymerization vessel. The purpose of the present invention is to provide a method for producing a vinyl chloride polymer, which comprises heating a charging pipe leading into a polymerization vessel and a charging port of the polymerization vessel from the outside after introducing the polymer into a polymerization vessel.

In 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 in the polymerization vessel to which the pipes are connected. However, it also includes the case where other piping and charging ports, such as monomer or other additive supply piping and charging ports, are heated from the outside as necessary.

In the method of the present invention, after the polymerization initiator is charged, the piping and the charging port are heated from the outside, so that the polymerization initiator adheres to the piping and the charging port.
The remaining polymerization initiator is decomposed and removed. 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 heating temperature may be any temperature at which the polymerization initiator used is decomposed, and is usually preferably 80"C or higher, more preferably 100"C or higher, and heating at 100"C or higher will cause the polymerization initiator to decompose. Decomposition can be carried out quickly.

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 ethylene, propylene, 1-butene, 1-pentene, and
Hexene, ■-heptene, 1-octene, ■-nonene,
α-olefins such as 1-decene, 1-undecene, ■-dodecene, 1-tridecene, and 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; monomers copolymerizable with geothermal vinyl, 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 bromine Examples include oil-soluble emulsifiers such as bilene oxide block copolymer; water-soluble emulsifiers such as polyoxyethylene sorbitan monolaure-1, polyoxyethylene glycerin oleate, and sodium laurate. These can be used alone or in combination of two or more.

The polymerization initiator used in the present invention is not particularly limited, and includes those used in the production of conventional vinyl chloride polymers, such as diisopropyl peroxydicarbonate,
Percarbonate compounds such as di-2-ethylhexylveroxydicarbonate and jetoxyethylperoxydicarbonate; L-butylperoxyneodecanate, m-butylperoxypivalate, mhexylperoxypivale-1 , perester compounds such as α-cumylperoxyneodecanate; acetylcyclohegylsulfonyl peroxide, 2,4°4-trimethylpentyl-2-peroxyphenoxyacetate, 3,
5. Peroxides such as 5-1-limethylhexanoyl peroxide; azo compounds such as azobis-2,4-dimethylvaleronitrile and azobis(4-methoxy-2,4-dimethylvaleronitrile); potassium persulfate , ammonium persulfate, hydrogen peroxide, and the like. These may be used alone or in combination of two or more.

In the present invention, the polymerization initiator is charged as it is, or as a solution in an organic solvent such as toluene or isoparaffin, or in an aqueous emulsion using a dispersant to adjust the viscosity so that it can be easily charged. It can be carried out as appropriate and is not particularly limited. The above-mentioned dispersant used to form an aqueous emulsion 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, polyvinyl chloride, etc. Examples include acrylic acid, polyoxyethylene sorbitan monolaurate, and the like.

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 regulators, chain transfer agents, PL+ regulators, 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 and 382 kg of partially saponified polyvinyl alcohol were placed in a stainless steel polymerization vessel with an internal volume of 20,001 kg.
After evacuating the inside of the polymerization vessel, 700 kg of vinyl chloride was charged. Next, di-2-ethylhexyl oxydicarbonate
After introducing 280 g of 1. into the polymerization vessel using a metering pump, steam (130"C) was passed through the pipe through which the polymerization initiator passed and the heating jacket 1- installed outside the charging port for 3 minutes. And the charging port was heated to 110°C.

While stirring the inside of the polymerization vessel, the temperature was raised to 66°C to start polymerization, and when the internal pressure of the polymerization vessel decreased to 6.0 kg/cffl, the polymerization was stopped, and unreacted monomers were 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, and evaluate using the criteria below. It was measured using the method. The results are shown in Table 1.

(Method for evaluating scale adhesion) A----No scale adhesion.

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

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

(Method for measuring the amount of residual solvent) 5 g of the obtained polymer was placed in a vial, heat-treated at 130°C for 30 minutes, and the gas phase of the vial was analyzed by gas chromatography, and the amount of residual solvent was measured. is expressed in ppm.

Examples 2 to 3 After repeating the same polymerization as in Example 1 100 times (Example 2) or 500 times (Example 3) on each side, the adhesion state of the polymer scale was similarly observed and the obtained The amount of 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 (
Comparative Example 2) Polymerization was carried out in the same manner as in Example 1 (7), except for washing in Comparative Example 2), and the adhesion state of the polymer scale was similarly observed and the amount of residual solvent in the obtained polymer was measured. It is 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 observed in the same manner and in the obtained polymer. The residual solvent level was measured.

The results are shown in Table 1.

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

Furthermore, according to the method of the present invention, the polymerization initiator that adheres to and remains on the piping and charging port can be removed without using a cleaning solvent, and even if cleaning is performed using a solvent, it is much easier than conventional methods. It can be done with small amounts of solvent.

Agent Patent Attorney Shushi Iwamiya

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, after a polymerization initiator is introduced into the polymerization vessel, the preparation piping leading to the polymerization vessel and the polymerization A method for producing a vinyl chloride polymer, characterized by heating a charging port of a vessel from the outside.