JPH09176231A - Production of vinyl chloride resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a good-quality vinyl chloride resin which suffers little from a decrease in bulk density due to electronic charging by adding a specified compound to a resin powder obtained from a slurry containing a vinyl chloride resin. SOLUTION: A slurry containing a vinyl chloride resin is obtained by a suspension polymerization process comprising polymerizing a vinyl chloride monomer or a mixture thereof with a vinyl monomer such as an alkyl vinyl ester (e.g. vinyl acetate, an alkyl vinyl ether (e.g. cetyl vinyl ether or an olefin monomer (e.g. ethylene) in an aqueous medium in the presence of a suspending agent and a polymerization initiator. To a cake obtained by dehydrating this slurry or a resin powder obtained by drying this cake, a solution of dispersion of 0.001-0.5 pt.wt., per 100 pts.wt. vinyl chloride resin, compound represented by the formula (wherein R<1> to R<3> are each a 1-20C alkyl, provided that at least one of them is an 8-18C alkyl) in water, methanol, acetone or the like is added.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a vinyl chloride resin by a suspension polymerization method,
More specifically, it relates to a method for producing a vinyl chloride resin having excellent powder fluidity.

[0002]

2. Description of the Related Art Vinyl chloride resins are generally produced by a suspension polymerization method, and after separation from the slurry after polymerization, drying, etc., they are transported by air and stored or packed.

However, the vinyl chloride resin is charged with static electricity due to friction with itself or other substances during transport and bagging, and its fluidity is lowered, and its bulk specific gravity is higher than that of the vinyl chloride resin immediately after production. Since it decreases, it becomes extremely difficult to handle, and there is a problem that work is seriously hindered. Conventionally known methods for reducing the adverse effects of such resin charging are adding a surfactant to the vinyl chloride resin or blowing steam into the vinyl chloride resin to adjust the humidity.

[0004]

However, in the conventional method of adding a surfactant, not only the decrease in bulk specific gravity due to the charging of the resin cannot be sufficiently prevented, but also the thermal stability and the initial temperature of the resin are improved. It has a drawback that it adversely affects the colorability and the like. In addition, the method of blowing steam has drawbacks such as an increase in required labor force and complication of equipment.

Therefore, an object of the present invention is to provide a method for producing a vinyl chloride resin having good quality, which is less likely to cause a decrease in bulk specific gravity due to electrification by adding a specific compound. is there.

[0006]

Means for Solving the Problems As a result of intensive studies for solving the above problems, the present inventors have found that addition of a specific compound makes it difficult for the vinyl chloride resin to be reduced in bulk specific gravity due to charging. Moreover, a method for producing a vinyl chloride resin having good quality has been found, and the present invention has been completed.

That is, according to the present invention, when a vinyl chloride resin is suspension polymerized in an aqueous medium to produce a vinyl chloride resin, the vinyl chloride resin-containing slurry is obtained by dehydrating the slurry. 0.001 to 0.5 parts by weight of the compound represented by the following formula (1) in 100 parts by weight of the vinyl chloride resin described above is added to the obtained cake or the resin powder obtained by drying the cake. The present invention provides a method for producing a vinyl chloride-based resin, which is characterized by adding a part thereof.

[0008]

Embedded image

(In the formula, R1, R2 and R3 each independently represent an alkyl group having 1 to 20 carbon atoms.) The present invention is described in detail below.

In the present invention, the vinyl chloride resin is produced by the suspension polymerization method.

Examples of the vinyl chloride resin in the present invention include vinyl chloride homopolymer resin and vinyl chloride copolymer resin.

In the present invention, the vinyl chloride-based monomer for producing the vinyl chloride-based resin is a vinyl-based monomer that can be copolymerized with a vinyl chloride monomer or a vinyl chloride monomer and a vinyl chloride monomer. Examples include a mixture with a monomer. Examples of vinyl monomers copolymerizable with vinyl chloride monomers include alkyl vinyl esters such as vinyl acetate; alkyl vinyl ethers such as cetyl vinyl ether; olefinic monomers such as ethylene and propylene; methyl acrylate. , Alkyl acrylates such as ethyl acrylate and propyl acrylate; and methacrylic acid alkyl esters such as methyl methacrylate, ethyl methacrylate and propyl methacrylate.

The suspension polymerization of the vinyl chloride resin in the present invention may be carried out by a generally known method, for example, in the presence of a vinyl chloride monomer in the presence of a suspending agent and a polymerization initiator.
A method of polymerizing in an aqueous medium can be mentioned, and a slurry containing a vinyl chloride resin can be obtained by such a suspension polymerization method.

In the present invention, a slurry containing a vinyl chloride resin, a cake obtained by dehydrating the slurry or a resin powder obtained by drying the cake is added by the formula (1). The compounds shown are R1, R2, R
3 are each independently an alkyl group having 1 to 20 carbon atoms, and any compound can be used as long as it is represented by the formula (1). Since it is possible to more effectively prevent the decrease in bulk specific gravity due to charging, at least one of the alkyl groups represented by R1, R2, and R3 has an alkyl group having 8 to 18 carbon atoms. More preferable.

Examples of the compound represented by the formula (1) in the present invention include decyldimethylcarboxymethylbetaine, dodecyldimethylcarboxymethylbetaine, tetradecyldimethylcarboxymethylcybetaine, hexadecyldimethylcarboxymethylbetaine, octadecyldimethylcarboxymethylbetaine. Etc. can be mentioned.

The addition amount of the compound represented by the formula (1) in the present invention is 0.001 to 0.5 parts by weight based on 100 parts by weight of the vinyl chloride resin. If the addition amount is less than 0.001 part by weight, it is impossible to prevent the bulk specific gravity from being extremely reduced due to the electrification of the obtained vinyl chloride resin. Further, even if the amount added exceeds 0.5 parts by weight, the desired effect does not increase any more, which is not economical.

The method of adding the compound represented by the formula (1) in the present invention is a slurry containing a vinyl chloride resin,
Any method may be used as long as it can be added to the cake obtained after dehydrating the slurry or the resin powder obtained by drying the cake, powder, solution or dispersion. Since it can be added in a liquid state or the like and can be easily and uniformly added, it is preferable to add it in the form of a solution or dispersion. The solvent for preparing the solution or dispersion of the compound represented by the formula (1) is not particularly limited, but examples thereof include water, methanol, ethanol, isopropyl alcohol, acetone, or a mixed solvent thereof.

[0018]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

The resins obtained in Examples and Comparative Examples were evaluated under the conditions shown below.

-Bulk Specific Gravity Measurement Test- The obtained resin is left in a constant temperature and humidity chamber at a temperature of 23 ° C. and a relative humidity of 50% for 48 hours, and then the bulk specific gravity is measured according to JIS K 6
It was measured by the method of 721.

The resin left for 48 hours under the same conditions as above was treated with a Brabender planetary mixer at 60r.
After stirring for 2 minutes at pm, bulk specific gravity was determined by the same method as above, and the antistatic properties were evaluated by comparing them.

-Heat Stability- 100 parts by weight of the obtained resin was mixed with 1.0 part of tribasic lead sulfate, 1.5 parts of lead stearate and 0.5 part of calcium stearate, and rolled at 190 ° C. After kneading with a machine for 5 minutes, a sheet with a thickness of 1 mm is prepared, and this sheet is
It was placed in an oven at ℃ and the time until blackening was measured.

Example 1 100 parts by weight of vinyl chloride monomer, 150 parts by weight of deionized water, 0.1 part by weight of partially saponified polyvinyl alcohol, 0.04 part by weight of 2-ethylhexyl peroxydicarbonate were placed in a stainless steel polymerization vessel. Was charged, polymerization was carried out at a temperature of 57 ° C., and when the pressure in the polymerization vessel reached 6.0 kg / cm ² G, unreacted vinyl chloride monomer was recovered and dehydrated to contain 20% by weight of water. A vinyl chloride resin cake was obtained. After adding a 1% aqueous solution of octamethyldimethylcarboxymethyl betaine to the resin cake thus obtained so that the addition amount of octamethyldimethylcarboxymethyl betaine is 0.01 parts by weight with respect to 100 parts by weight of vinyl chloride resin, It was fluidized and dried at 70 ° C. for 2 hours to obtain a vinyl chloride resin.

Table 1 shows the evaluation results of the obtained vinyl chloride resin.
Shown in

The obtained vinyl chloride resin had an excellent antistatic property and did not deteriorate in thermal stability.

Examples 2 to 5 Example 1 was repeated except that the addition amount and addition conditions of octamethyldimethylcarboxymethyl betaine were changed to those shown in Table 1.
A vinyl chloride resin was obtained in the same manner as in.

Table 1 shows the evaluation results of the obtained vinyl chloride resin.
Shown in

The obtained vinyl chloride resin had an excellent antistatic property and did not deteriorate in thermal stability.

Comparative Example 1 A vinyl chloride resin was obtained in the same manner as in Example 1 except that octamethyldimethylcarboxymethyl betaine was not added.

Table 1 shows the evaluation results of the obtained vinyl chloride resin.
Shown in

The obtained vinyl chloride resin was inferior in antistatic property.

[0032]

[Table 1]

[0033]

INDUSTRIAL APPLICABILITY The present invention relates to a method for producing a vinyl chloride resin having good thermal stability, which is unlikely to cause a decrease in bulk specific gravity due to charging, and has a high industrial value.

Claims (1)

[Claims] 1. A suspension-polymerization of a vinyl chloride monomer or a mixture of vinyl-based monomers having vinyl chloride monomer as a main component (hereinafter referred to as vinyl chloride-based monomer) in an aqueous medium, In producing a vinyl chloride resin, a slurry containing the vinyl chloride resin, a cake obtained after dehydrating the slurry, or a resin powder obtained by drying the cake is added with the following formula (1 ) 0.001 to 0.5 part by weight of the compound represented by the formula (1) is added to 100 parts by weight of the vinyl chloride resin, and a method for producing a vinyl chloride resin. Embedded image (In the formula, R1, R2, and R3 each independently represent an alkyl group having 1 to 20 carbon atoms.)