JPS6042245B2 - Polymerization method of vinyl chloride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an improved process for the homo- or copolymerization of vinyl chloride.

When vinyl chloride is polymerized alone or together with monomers that can be copolymerized (hereinafter simply referred to as polymerization), the monomer is exposed to the inner wall of the polymerization tank, the backflow condenser, stirring blades, baffle plates, and various attached piping connections during the polymerization operation. The cooling capacity of the polymerization tank may be reduced because the polymer adheres to the parts of the equipment that come in contact with it, or once the polymer has adhered and peeled off, it may be mixed into the vinyl chloride homopolymer or copolymer (hereinafter referred to as the product). or reduce the quality of the product.

A problem arises. Therefore, it is customary to clean the inside of the polymerization tank after each polymerization and then perform the polymerization again, but this requires a great deal of labor and time, resulting in a decrease in the operating rate of the polymerization tank and an increase in product costs. is bringing. Many methods have been proposed in the past for polymer adhesion to the inner wall of the polymerization tank, but although these methods are effective in preventing polymer adhesion, they may slow down the polymerization rate or affect the physical properties of the product. There are various drawbacks such as deterioration, and none of these methods are satisfactory for industrial use. The purpose of the present invention is to:
It is an object of the present invention to provide a practical polymerization method that does not cause the above-mentioned adverse effects and sufficiently prevents polymer adhesion.

When polymerizing vinyl chloride, the present inventors found that if they applied propylene glycol ester alginate in advance to the inner walls of the polymerization tank and other parts of the polymerization equipment and equipment attached to the polymerization tank that come into contact with the monomer during the polymerization operation, the polymer It was discovered that adhesion was greatly reduced, and even a small amount of attached polymer could be easily removed by washing with water, and there were no adverse effects such as slowing down the reaction time during polymerization or deteriorating various physical properties of the product. , arrived at the present invention. The term alginate propylene glycol ester as used in the present invention refers to an ester in which propylene oxide is added to the carboxyl group of alginic acid under heat and pressure. It is obtained by adding an alkali as a catalyst and carrying out esterification at about 70°C. Alginate gel is obtained by acid treatment of sodium alginate extracted with sodium carbonate from fresh seaweed. In carrying out the present invention, alginate propylene glycol ester is applied to the inner wall of a polymerization tank in the form of a solution dissolved in a solvent.

In this case, the medium of the coating liquid is not particularly limited, and any solvent such as water, alkaline aqueous solution, etc., in which alginate propylene glycol ester is soluble may be used. The preparation of the coating liquid is not particularly limited, and may be carried out under conditions such that the alginate propylene glycol ester is dissolved in the solvent. It is not clear why polymer adhesion can be prevented by applying the alginate propylene glycol ester of the present invention to the inner wall of a vinyl chloride polymerization tank, etc., but it is probably because the alginate propylene glycol ester has -
It is thought that this is because polar groups represented by 0H groups act as hydrophilic groups and make the wall surface of the portion of the polymerization tank that comes into contact with the monomer hydrophilic. In fact, it has been observed that while untreated walls such as polymerization tanks exhibit considerable water repellency, walls treated with the present invention become extremely wettable with water and exhibit hydrophilic properties. Ru. Therefore, it can be considered that the monomer is prevented from coming into contact with the wall surface during the polymerization reaction, which is effective in preventing polymer adhesion.

In carrying out the present invention, a solution in which propylene glycol alginate is dissolved is applied to the inner wall of the polymerization tank, etc., and the concentration of propylene glycol alginate can be in the range of 0.01 to 20% by weight. Yes, preferably. It is convenient for the coating work to use it in a range of 0.05 to 5% by weight.

In the present invention, application does not refer to the mode of work, but means that propylene glycol alginate is present on the wall of the vessel as a result, and the method of application is not particularly limited, but it is usually applied by brushing or spraying. The amount of application is not limited, but is usually 0.
It is preferable to set it as 005-10y/d. Coating may be carried out before the start of polymerization for each batch, or polymerization may be carried out continuously for several batches or more after coating by simply washing with water. Furthermore, the polymerization to which the present invention can be applied is not only the homopolymerization of vinyl chloride, but also monomers copolymerizable with vinyl chloride, such as olefins such as ethylene and propylene, vinyl monomers such as vinyl acetate and styrene, maleic acid, fumaric acid, etc. It can be effectively applied to copolymerization with dicarboxylic acid monomers such as fumaric acid esters.

Furthermore, the polymerization formation applicable to the present invention can be effectively applied to aqueous suspension polymerization of the above monomers, aqueous emulsion polymerization of the above monomers, and so-called bulk polymerization in which only the above monomers are used without a polymerization medium, under each usual polymerization condition.

According to the method of the present invention, the effect of preventing polymer adhesion is much greater than that of conventional methods, and there are no adverse effects such as a slowing of the polymerization rate or deterioration of various physical properties of the product.

The present invention will be explained below with reference to Examples.

Example Commercially available propylene glycol alginate was dissolved in an aqueous solution of caustic soda, and the following ingredients were added: 1% by weight of propylene glycol alginate, 2% by weight of caustic soda, and 9% by weight of water.
A coating solution was prepared.

This coating solution was sprayed onto the inner wall of a stainless steel polymerization tank having an internal volume of 7 spaces. After such treatment, deionized water 3
000k9, vinyl chloride monomer 2000k9, t-butylperoxypivalate 0.6kg, and partially saponified polyvinyl alcohol 2k9 with a degree of saponification of 80 mol% were charged, and the reaction was carried out at 5rc until the pressure reached 6.5kg/CFlfG. continued. After the reaction was completed, the unreacted vinyl chloride monomer was collected, and after the polymer slurry was discharged, the weight of the polymer adhering to the inner wall of the polymerization tank was determined. The polymer slurry was dehydrated and dried to obtain a product, and as shown in Table 1, according to the method of the present invention, the amount of polymer adhesion was significantly small.
Additionally, the adhered polymer could be easily washed away with simple water washing.

The physical properties of the obtained product were also excellent. Comparative Example The same procedure as in Example was carried out, except that the alginate propylene glycol ester coating solution was not applied.

As shown in Table 1, a large amount of polymer adhered to the inner wall of the polymerization tank. 1 According to JIS K6721 2 According to JIS K6721 3 Fishery test method PVClOOV2 -Ethylhexyl phthalate 50 da Toa Rika stabilizer Adbastab BC-1 100 J5y The above mixture was kneaded for 5 minutes using two rolls at 150°C with a roll spacing of 0.3wn, Create a sheet.

Thereafter, the number of fisheyes present in an area of 10 cm x 10 cm was counted by looking through the area. 4 Based on mercury intrusion method.

Claims (1)

[Claims] 1. When vinyl chloride is polymerized alone or together with a monomer that can be copolymerized with vinyl chloride in an aqueous medium or in bulk, alginic acid is added to the inner wall of the polymerization tank and the parts of the equipment that will come into contact with the monomer during the polymerization operation. A method for monopolymerizing or copolymerizing vinyl chloride, which comprises applying propylene glycol ester.