JPS60158206A - Suspension polymerization of vinyl chloride - Google Patents

Abstract

PURPOSE:To make it possible to perform polymerization without polymer deposition and degradation of product quality, by suspension-polymerizing vinyl chloride in the presence of a specified suspension stabilizer in a reactor equipped with a reflux condenser which can allow jacket cooling of the entire area in contact with vinyl chloride. CONSTITUTION:The aqueous suspension polymerization of vinyl chloride or a mixture thereof with a monomer copolymerizable therewith is conducted in a reactor equipped with a reflux condenser by using a suspension stabilizer comprising a combination of PVA having a relatively low degree of saponification (one having a degree of saponification <=80%, preferably <=70%) with an oil- soluble surfactant (e.g., polyoxyethylene lauryl ether or an oil-soluble cellulose ether). Said reflux condenser has a structure which can allow jacket cooling of the entire area in contact with vinyl chloride. In this way, it becomes possible to prevent polymer deposition on the inside surface of the reflux condenser and the connective part between it and the reactor and to perform the suspension polymerization of vinyl chloride without degradation of product quality.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing vinyl chloride resin using a reflux condenser, which prevents polymer adhesion on the inner surface of the reflux condenser and the connection part with the reactor without reducing product quality. This is a manufacturing method that prevents

In the production of vinyl chloride resin, a method is used in which a reflux condenser is attached to the reactor to increase heat removal capacity, but polymers adhere to the inside of the reflux condenser and the connection part with the reactor. Therefore, not only the heat removal ability of the reflux condenser is reduced, but also the Fische eye properties are inevitably reduced due to the adhering polymer being mixed into the product.

In extreme cases, the connection to the reactor may become blocked.

Various methods have been proposed to prevent polymer adhesion, but one method involves bringing demineralized water or a nitrite bath solution into contact with the inner surface of the reflux condenser or the connection to the reactor to prevent polymer adhesion. (Unexamined Japanese Patent Publication No. 50-73989゜50-73990.5l
-84887) has the disadvantage of deteriorating the particle size characteristics of the product polymer, and the method of charging the reacted raw vinyl chloride monomer from the top of the reflux condenser (Japanese Patent Application Laid-Open No. 1983-58391) requires complicated operations. That's not practical.

The present invention takes into consideration the shortcomings of the conventional methods, and solves the problem of reflux condenser inner surface and This is a method that prevents polymer adhesion at the connection to the reactor to the extent that there is no practical problem.

The present invention uses polyvinyl alcohol, which has a relatively low degree of saponification, in combination with an oil-soluble surfactant or oil-soluble cellulose ether as a suspension stabilizer to prevent foaming caused by the suspension stabilizer.

Furthermore, the present invention provides jacket cooling for the connecting part between the reflux condenser and the reactor and the upper and lower parts of the reflux condenser, thereby increasing the amount of vinyl chloride monomer condensed in these parts, which is entrained in the bubbles and bubbles caused by the suspension stabilizer. This increases the effect of cleaning the polymerization initiator, and also lowers the temperature of the area to inhibit polymer formation.

Suspension stabilizers include polyvinyl alcohol with a relatively low saponification degree of 70 degrees or less, preferably 70 degrees or less, and oil-soluble cellulose ethers, phosphoryoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, etc. Use with ionic oil-soluble surfactant. The combined use ranges from α01 to α06 parts by weight of partially saponified polyvinyl alcohol and 0.01 to 104 parts by weight of oil-soluble surfactant, in a ratio of oil-soluble surfactant/partially saponified polyvinyl alcohol of 1 to 3. . Similarly, the structure of the jacket is not particularly limited as long as it can achieve the object of the present invention.

The method of the invention can be used in aqueous suspension polymerizations commonly practiced in the art.

That is, the ratio of vinyl chloride to water is 100 to 200 parts by weight of water to 100 parts by weight of vinyl chloride, and the polymerization temperature is 55 to 70°C.

In addition to vinyl chloride, it can also be applied to cases where other monomers copolymerizable with vinyl chloride, such as ethylene, propylene, vinyl acetate, acrylic acid and esters thereof, are copolymerized.

As for the polymerization initiator, a radical generating initiator such as peroxide such as lauryl peroxide and azonitrile such as azobisisobutyronitrile is used.

Hereinafter, the present invention will be specifically explained with reference to Examples.

(Example 1) A 5 ytt multi-tubular reflux condenser was attached to the gas phase of the reactor, and 150 parts of water, 1 part saponified polyvinyl alcohol (degree of saponification 70) α04 parts, and 1102 parts of polyoxyethylene lauryl ether were added. After preparing and degassing, vinyl chloride monomer 1
I have prepared 00 copies. Raise the temperature while stirring to start the reaction,
The reaction was carried out at 58°C for 6 hours.

The reflux condenser was operated at the start of the reaction, and the upper and lower parts of the reflux condenser and the reactor connecting pipe were also jacket-cooled. The overall heat transfer coefficient of the reflux condenser! 100 Kca4/
As a result of repeating polymerization within the range of maintaining m'H"c or higher, approximately 2
90 polymerizations were possible.

(Example 2) The difference from Example 1 was that partially saponified polyvinyl alcohol with a degree of saponification of 80 degrees was used, and the number of possible polymerizations was reduced to about 250.

(Comparative Example 1) The difference from Example 1 was that water-soluble cellulose ether was used instead of polyoxyethylene lauryl ether, and the number of polymerizations possible was reduced to about 190.

(Comparative Example 2) The difference from Example 1 was that partially saponified polyvinyl alcohol having a degree of saponification of 90 degrees was used, and the number of possible polymerizations was reduced to about 100.

(Comparative Example 3) The difference from Example 1 is that partially saponified polyvinyl alcohol with a degree of saponification of 90% was used, water-soluble cellulose ether was used instead of polyoxyethylene lauryl ether, and the upper and lower parts of the reflux condenser and Due to the fact that jacket cooling was not performed at the connection part with the reactor, the possible number of polymerizations was 6.
It has decreased to 5. (Refer to Table 1) Based on the above results, the reflux condenser was cooled by jacket cooling the upper and lower parts of the reflux condenser and the connecting part with the reactor, and by using polyvinyl alcohol with a relatively low degree of saponification as the suspension stabilizer. Adhesion of the polymer to the inner surface can be prevented to the extent that there is no practical problem.

The effect can be further enhanced by using oil-soluble cellulose ether or oil-soluble surfactant in combination.

Regarding the quality, in Comparative Example 2.3, Fih's eye deteriorated at a rate of about 1 in every 20 polymerizations, but in Example 1.2 and Comparative Example 1, there was no problem.

The overall heat transfer coefficient of the reflux condenser is calculated from 2 = internal temperature of the reflux condenser, 5: reflux condenser cooling water inlet/flow rate/temperature, and 7: reflux condenser cooling water outlet temperature in Figure 1.

[Brief explanation of the drawing]

Figure 1 shows the apparatus used in the experiment of the embodiment of the present invention.The reactor 1 is equipped with a reflux condenser 2, and 5.7 is the cooling water inlet of the jacket of the main body.・This is the outlet piping. A jacket is attached to the upper and lower parts of the reflux condenser and the connection part with the reactor, and reference numerals 4.6 are cooling water inlet and outlet pipes. Patent applicant: Toyo Soda Kogyo Co., Ltd.

Claims (3)

[Claims] (1) When performing aqueous suspension polymerization of vinyl chloride or a mixture of vinyl chloride and monomers that can be copolymerized with it in a reactor equipped with a reflux condenser, polyvinyl with a low degree of saponification is used as a suspension stabilizer. A suspension polymerization method for vinyl chloride, characterized by using alcohol and an oil-soluble surfactant or an oil-soluble cellulose ether together, and using a reflux condenser having a structure capable of cooling the entire surface in contact with vinyl chloride with a jacket. . (2) As a suspension stabilizer, a non-ionic oil-soluble surfactant selected from polyvinyl alcohol with a chemical degree of 80 degrees or less and oil-soluble cellulose ether, polyoxyethylene alkyl ether, and polyoxyethylene alkyl allyl ether The method for suspension polymerization of vinyl chloride according to claim 1, which uses a copolymer. (3) A method for converting vinyl chloride according to claim 1 using a reflux condenser having a structure in which jackets are installed at the upper and lower parts and at the connection part with the reactor so that the entire surface in contact with vinyl chloride can be cooled by the jacket. Suspension polymerization method.