JPH0463803A - Preparation of vinyl chloride resin - Google Patents

Abstract

PURPOSE:To eliminate the variation in polymn. time and prepare a vinyl chloride resin in a short time by charging a polymn. kettle with water and additives, feeding a surfactant beneath the water level in the kettle, subjecting the contents in the kettle to a vacuum deaeration treatment, feeding vinyl chloride, and starting the polymn. CONSTITUTION:After a polymn. kettle is charged with water and other additives, a surfactant (e.g. sodium dodecylbenzenesulfonate) is fed beneath the water level in the reactor; the contents of the kettle is subjected to a vacuum deaeration treatment to remove oxygen in the kettle and oxygen dissolved in the water; and vinyl chloride or a mixture thereof with a copolymerizable vinyl monomer (e.g. acrylic acid) is fed thereto to start the polymn. As the surfactant is fed beneath the water level, foaming during the vacuum deaeration treatment is avoided, and thus the polymn. time can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing vinyl chloride resin.

[Prior Art] Generally, vinyl chloride resin, especially vinyl chloride resin for base processing, is manufactured by emulsion polymerization, fine suspension polymerization, and seeded emulsion polymerization. An activator is used.

However, surfactants cause foaming and have been a problem in manufacturing.

Specifically, water and surfactant in a polymerization can.

After adding other necessary additives, vacuum degassing is performed to remove oxygen from the polymerization reactor and dissolved oxygen from the water.
At this time, since the surfactant is present, the vacuum is removed to remove bubbles, so it is necessary to inject nitrogen after vacuum to suppress the bubbles, and then create a vacuum again. However, even with this, a sufficient degree of vacuum cannot be raised, and oxygen remains in the polymerization reactor, which impedes the polymerization reaction, prolongs the polymerization reaction time, and causes the polymerization time to vary.

[Problems to be Solved by the Invention] The present inventors suppressed foaming caused by a surfactant during vacuum operation of a polymerization can, sufficiently removed oxygen from the polymerization can to eliminate variations in polymerization time caused by residual oxygen, and shortened the polymerization time. As a result of intensive studies to develop a method to do so, the present invention was discovered.

[Means for Solving the Problems] That is, the present invention is characterized in that after each polymerization, water and other additives are charged, a surfactant is injected from below the water surface in the polymerization area, and a vacuum degassing operation is performed. The present invention relates to a method for producing vinyl chloride resin.

In other words, because the surfactant that causes foaming is present under the water surface in the polymerization area, foaming on the water surface disappears.
After evacuating, it is necessary to fill in nitrogen and evacuate again, but by performing only one vacuum operation, the degree of vacuum can be sufficiently increased compared to the conventional method, and the time for vacuum operation can be shortened.

Furthermore, since oxygen in the polymerization zone is sufficiently removed, the polymerization time is shortened and there is no variation in the polymerization time.

The method for producing vinyl chloride resin in the present invention (17) usually includes an emulsion polymerization method, a fine suspension polymerization method, a seeded emulsion polymerization method, etc., but it is applicable to all production methods that use a surfactant in an aqueous medium. .

In the present invention, below the water surface in the polymerization zone means the part below the water surface in the polymerization zone after charging a predetermined amount of water and other additives for each polymerization.

The surfactant may be charged from any part below the water surface, but it is preferable to charge it from the lowest part of each polymerization, which is farthest from the water surface.

When near the surface of the water, dissolved oxygen is removed from the surface of the water during vacuum operation, causing foaming to occur due to the surfactant near the surface of the water.

In the present invention, vinyl compounds copolymerized with vinyl chloride include vinyl acetate and vinyl propionate.

Vinyl esters such as vinyl myridate, vinyl oleate, vinyl benzoate, acrylic acid, methacrylic acid,
Unsaturated carboxylic acids such as maleic acid, fumaric acid, cinnamic acid or their anhydrides, methyl, ethyl, butyl acrylate,
Esters such as octyl and benzyl, esters of methacrylic acid such as methyl, ethyl, butyl, octyl, and benzyl, unsaturated carboxylic acid esters such as maleic acid ester, fumaric acid ester, and cinnamic acid ester, vinyl methyl ether, vinyl amyl ether , vinyl ethers such as vinyl phenyl ether, monoolefins such as ethylene propylene, butene, and pentene, vinylidene chloride, styrene and its derivatives, acrylonitrile, methacrylonitrile, and one or more ordinary vinyl compounds that can be radically copolymerized with vinyl chloride. It is about.

In the present invention, surfactants include alkyl sulfate ester salts such as sodium lauryl sulfate and sodium myristyl sulfate, alkylaryl sulfonates such as sodium dodecylbenzenesulfonate and potassium dodenylbenzenesulfonate, sodium dioctylsulfosuccinate, Sulfosuccinate ester salts such as sodium dihexyl sulfosuccinate, fatty acid salts such as ammonium laurate and potassium stearate, polyoxyethylene alkyl sulfate ester salts,
Anionic surfactants such as polyoxyethylene alkylaryl sulfate salts, sorbitan monooleate,
Conventionally known surfactants such as sorbitan esters such as polyoxyethylene sorbitan monostearate, nonionic surfactants such as polyoxyethylene alkylphenylethyls and polyoxyethylene alkyl esters can be used.

[Effects of the Invention] The method of the present invention shortens the vacuum operation time, eliminates variations in polymerization time that tend to shorten polymerization time, increases productivity, and provides stable manufacturing operation.

[Example] Next, the method of the present invention will be explained in more detail by referring to an example.

Example 1 After charging 300 kg of deionized water and 15 kg of seed polymer particles containing an organic peroxide into a polymerization reactor, 400 g of sodium lauryl sulfate was injected from the bottom of each polymerization reactor.

Then, vacuum operation was performed to create a vacuum down to the vapor pressure of water temperature. The degree of vacuum at this time was 8° Torr. Thereafter, 400 kg of vinyl chloride monomer was charged and polymerization was carried out at a polymerization temperature of 48°C.

Example 1 was repeated 10 times to confirm reproducibility.

The results are shown in Table 1.

Comparative Example 1 The surfactant sodium lauryl sulfate was injected in the same manner as in Example 1, except that it was injected from the top of the polymerization reactor.

In this case, since the surfactant is injected from the top, foaming occurs during injection, and the surfactant is present on the water surface, resulting in intense foaming at approximately 160 Torr under vacuum.
The degree of vacuum could only be obtained up to .

Comparative Example 1 was repeated 10 times to confirm reproducibility.

The results are shown in Table 1.

Polymerization was carried out in the same manner.

A degree of vacuum up to gQTorr was obtained.

Example 2 was repeated 10 times to confirm reproducibility.

The results are shown in Table 2.

Comparative Example 2 The surfactant sodium lauryl sulfate was injected in the same manner as in Example 2, except that it was injected from the top of the polymerization reactor.

In this case, bubbling was intense during vacuum operation, and the degree of vacuum obtained was about 100 Torr.

Comparative Example 2 was repeated 10 times to confirm reproducibility.

The results are shown in Table 2.

Example 2 Same as Example 1 except that the polymerization temperature was set at 64° C. Table 1 Table 2 From the results of Tables 1 and 2, the vacuum degree ( It can be seen that the polymerization time is shortened, and the fluctuation power (i) of the polymerization time is decreased.

Claims (1)

[Claims] (1) When emulsion polymerizing vinyl chloride or a mixture of vinyl chloride and a vinyl compound copolymerizable with it in an aqueous medium, after charging water and other additives to a polymerization can, a surfactant is added to the surface of the water in the polymerization can. A method for producing vinyl chloride resin, which comprises charging from below, performing a vacuum degassing operation, and then charging vinyl chloride to start polymerization.