JPH04100804A - Production of vinyl chloride polymer powder - Google Patents

Abstract

PURPOSE:To obtain the title powder difficultly chargeable with static electricity and excellent in flow, etc., by polymerizing a vinyl chloride monomer in an aqueous medium and adding a specified amount of a fluorine-containing nonionic surfactant to the polymerization system after the conversion reaches a specified value. CONSTITUTION:A vinyl chloride monomer or a vinyl monomer mixture based thereon is polymerized in an aqueous medium. After the conversion reaches 70%, 0.0001-0.5 pt.wt., per 100 pts.wt. formed polymer, fluorine-containing nonionic surfactant (e.g. Surflon S-382, a product of Asahi Glass Co.) is added to the polymerization system. By dehydration and drying after the polymerization, a vinyl chloride polymer powder is obtained. The obtained powder suffers neither the problem of being charged with static electricity and stopping the inside of a dryer or a transportation pipe by forming a block during drying or transporation, etc., nor the problem of decreasing in its bulk density.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for producing a vinyl chloride polymer powder having good fluidity.

[Conventional technology]

Vinyl chloride polymers are produced, for example, by suspension polymerization, emulsion polymerization, or bulk polymerization. However, this polymer powder tends to be charged with static electricity during drying or transportation, resulting in decreased fluidity and formation of blocks, which can clog the inside of the dryer or the transportation pipe. Furthermore, since the bulk specific gravity of a charged polymer powder is significantly reduced, for example, when measuring by the volumetric method, there is a problem in that there is a discrepancy between the actual weight and the actual weight. These phenomena occur significantly in winter when temperature and humidity are low. Various methods have been proposed to prevent static electricity, but by adding nonionic surfactants, anionic surfactants, or cationic surfactants to vinyl chloride polymer powder, water retention can be achieved on the surface of the polymer powder. A common method is to give it sex. However, the above-mentioned method cannot sufficiently prevent a decrease in the bulk specific gravity or fluidity of the polymer powder, and may also result in a decrease in product stability. In addition, scale adhesion on the inner wall of the polymerization can is also a problem in conventional manufacturing methods.

[Problem to be solved by the invention]

The present invention was made in order to solve the above-mentioned problems, and it is possible to obtain a vinyl chloride polymer powder of high quality, which does not suffer from electrostatic charge, a decrease in bulk specific gravity, or a decrease in fluidity. An object of the present invention is to provide a method for producing a polymer powder.

[Means to solve the problem]

The method for producing a vinyl chloride polymer powder of the present invention, which has been made to achieve the above object, comprises adding vinyl chloride m1 or a mixture of vinyl monomers containing vinyl chloride monomer as a main component to an aqueous medium. After polymerization reached 70%,
0.0001-0 per 100 parts by weight of the produced polymer
．． 5 parts by weight of a fluorine-based nonionic surfactant is added to the polymerization system. The monomer raw material for the vinyl chloride polymer powder is vinyl chloride monomer alone, or 50% by weight or more of vinyl chloride monomer and other vinyl monomers that can be copolymerized with vinyl chloride monomer. It is a mixture of Examples of vinyl monomers copolymerizable with vinyl chloride monomers include vinyl esters such as vinyl acetate and vinyl propionate, methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate. Mention may be made of acrylic or methacrylic acid esters, olefins such as ethylene and propylene, vinyl ethers such as lauryl vinyl ether and isobutyl vinyl ether. Also, maleic anhydride,
Acrylonitrile, styrene, and vinylodene chloride can also be polymerized. These may be used singly or in combination. As a specific product of the fluorine-based nonionic surfactant, for example, Surflon S-3815-382 manufactured by Asahi Glass Co., Ltd.
, Senflo 51. manufactured by Positive Pressure Atlas. Monfro 52
, Monoflow 53, and Florado FC-170c, Fc-430, and FC-4:11 manufactured by Sumitomo 3M ■ are suitable. The fluorine-based nonionic surfactant is a polymer produced by
It is desirable to add 0.0001 to 0.05 parts by weight per 0.00 parts by weight. If the amount is less than o, oooi parts by weight, the fluidity of the polymerized polymer powder will not be improved. Even if more than 0.05 parts by weight is added, not only no further effect can be expected, but also the gelation rate during molding becomes slow. The fluorine-based nonionic surfactant is added after the polymerization rate of the reaction system reaches 70%. If it is added at a polymerization rate of less than 70%, it is not preferable because it will adversely affect the formation of polymer particles. When adding a fluorine-based nonionic surfactant to the polymerization system,
Low-viscosity liquid materials may be pumped as they are, but high-viscosity or solid materials may be diluted with a solvent or dispersed in water before being pumped. Furthermore, in the production method of the present invention, dispersion aids and polymerization initiators that have been conventionally used in the production of vinyl chloride polymers may be used. Dispersing aids include, for example, water-soluble cellulose ethers such as methylcellulose, ethylcellulose, bitroxyethylcellulose, hydroxypropylcellulose and hydroxypropylmethylcellulose, water-soluble or oil-retaining partially saponified polyvinyl alcohol, acrylic acid polymers, gelatin. water droplet polymers such as sorbitan monolaurate, sorbitan triolate, sorbitan monostearate, glycerin tristearate and oil bath emulsifiers such as ethylene oxide-propylene oxide block copolymers, boxoxyethylene sorbitan monolaurate, bojoxy These include water-temperature emulsifiers such as ethylene glycerol oleate and launonic acid, calcium carbonate, calcium nonate, and sodium dodecylbenzene sulfonate. These may be used singly or in combination. As the polymerization initiator, those conventionally used for vinyl chloride polymerization can be used. This includes, for example, carbonate compounds such as di-isopropyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate and di-2-ethyl peroxydicarbonate, t-butyl peroxypivalate, t- Perester compounds such as xyl peroxybivalate, a-cumyl peroxy neodecanate and 2.4.4-1-tumethylbenzene-2-peroxy 2-neodecanate, acetyl cyclohexyl sulfonyl peroxide,
2.4.4-Trimethylbenzene-2-peroxyphenoxy acetate, 3.5.5-Trimethylhexanoyl peroxide and peroxides such as lauroyl peroxide, azobis-2,4-dimethylvaleronitrile and azobis Azo compounds such as (4-methoxy-2,4=dimethylvaleronitrile), potassium persulfate, ammonium persulfate, hydrogen peroxide, cumene hydroperoxide, etc. can be used alone or in combination. . During polymerization, various polymerization conditions such as the method of charging an aqueous medium, vinyl chloride or a monomer mixture containing vinyl chloride, a dispersion aid, a polymerization initiator, etc. to a polymerization vessel, the charging ratio, and the polymerization temperature are conventional. You can do it in the same way. In the production method of the present invention, if necessary, a polymerization regulator, a chain transfer agent, a pH
Conditioner, gelling improver, antistatic agent, crosslinking agent, stabilizer,
It is also optional to add fillers, buffers, anti-scaling agents, etc. Furthermore, an antioxidant can be added to the polymerization system before the start of the polymerization, during the polymerization, or after the end of the polymerization for the purpose of suppressing the polymerization reaction and preventing deterioration of the produced polymer.

【Example】

The present invention will be explained in detail below. Example 1 980 kg of deionized water, 382 g of partially saponified polyvinyl alcohol, and 143 g of water-soluble methyl cellulose were charged into a stainless steel polymerization vessel with an internal volume of 2,000 ml, and after degassing the inside of the vessel, 700 kg of vinyl chloride monomer was charged.
Insert. While stirring the interior of the polymerization vessel, 280 g of di-2-ethylhexyl dicarbonate was injected as a polymerization initiator using a high-pressure pump, and at the same time the temperature began to rise to initiate polymerization.
Once the temperature inside the polymerization vessel has risen to 58°C, continue stirring while maintaining that temperature. When the polymerization rate reaches 85%, 100% of the produced polymer
0.0 part by weight of fluorine-based nonionic surfactant
Add 5 parts by weight and continue polymerization. As the fluorine-based nonionic surfactant, Surflon S-382 manufactured by Asahi Glass Co., Ltd. was used. The internal pressure of the polymerization vessel is 5.5 kg.
/cm"G, the reaction was stopped, unreacted monomers were collected, and then dehydrated and dried to obtain a vinyl chloride polymer powder. Example 2 Fluorine-based nonionic surfactant A vinyl chloride polymer powder was obtained in the same manner as in Example 1 except that Monoflow 52 manufactured by Seisei Atlas Co., Ltd. was used as the agent.Example 3 As a fluorine-based nonionic surfactant, Sumitomo Steel A vinyl chloride polymer powder was obtained in the same manner as in Example 1, except that Fluorado FC-431 manufactured by J-M ■ was used.Example 4 The amount of fluorine-based nonionic surfactant added was 0. A vinyl chloride polymer powder was obtained in the same manner as in Example 1, except that the amount was 0.01 parts by weight.Comparative Example 1 A powder of vinyl chloride polymer was obtained in the same manner as in Example 1, except that the fluorine-based nonionic surfactant was not added. A powder of a vinyl chloride polymer was obtained. Comparative Example 2 A vinyl chloride polymer was prepared in the same manner as in Example 1, except that 0.3 parts by weight of an amine cationic surfactant was added instead of the fluorine nonionic surfactant. A polymer powder was obtained. The following tests were conducted on the vinyl chloride polymer powder obtained in Examples 1 to 4 and Comparative Examples 1 and 2 above. Table 1 shows: J. Experimental results・Flowability test The obtained powder of each vinyl chloride polymer was heated at 0°C and 40% R.
After being left in the H environment for a day and night, JIS K-6721
100 cc of the sample was placed in a specified funnel for measuring bulk specific gravity, and the falling time from the funnel was determined as i++. In addition, each polymer powder that had been left overnight in the same manner was mixed for 5 minutes at 60 rpm using a Brabender planetary mixer, and then the falling time from the funnel was measured in the same manner as above. - Bulk specific gravity measurement test After each polymer powder was left in an environment of 0° C. and 40% RH for a day and night, the bulk specific gravity was measured according to the method specified in JIS K-6721. In addition, each polymer powder that had been left to stand day and night was mixed for 5 minutes at 60 rpm using a Brabender planetary mixer, and then the bulk specific gravity was measured in the same manner as above.・Thermal stability test Vinyl chloride polymer 100 parts by weight and the following compound Zinc stearate 25 parts by weight Barium stearate 07 parts by weight Tribasic lead sulfate
After adding 300 parts by weight of 0.5 parts by weight of dioctyl phthalate and kneading with rolls at 165° C. for 5 minutes, a sheet with a thickness of 1 mr+ is prepared. This sheet was placed in an oven at 195° C., and the time until it turned black was measured to determine thermal stability. Flowability Test-1 The test results of bulk specific gravity measurement test and thermal stability test are shown in Table 1. (Left below) The following is an experimental example in which the timing of addition of the fluorine-based nonionic surfactant was changed. Examples 5 to 7, Comparative Example 3 Polymer powders were obtained in the same manner as in Example 1, except that the timing of addition of the fluorine-based nonionic surfactant was changed to the conditions shown in Table 2. After the completion of polymerization, the state of scale adhesion inside the vessel was observed, and each of the obtained polymer powders was tested in Example 1.
Flowability tests and bulk specific gravity measurements were conducted in the same manner as above. Table 2 shows the test results. (Added to slurry after collecting one unreacted sheep) According to these test results, the vinyl chloride polymer powder obtained by the production method of the present invention has sufficient fluidity. , the bulk specific gravity did not fluctuate due to environmental changes (it was constant and stable, and the value was extremely close to the stability of specific gravity required for the standards of measurement using the volumetric method.Basic requirements such as thermal stability The characteristics are also fully satisfied. Also, the effect of suppressing scale adhesion on the walls of the polymerization tank during polymerization was obtained. [Effects of the Invention] As explained in detail above, the vinyl chloride polymer of the present invention According to the method for producing the combined powder, it is possible to produce a vinyl chloride polymer powder that is difficult to be charged.The produced polymer powder has a suppressed decrease in bulk specific gravity and fluidity. The quality required for a vinyl polymer is ensured.

Claims (1)

[Claims] 1. Polymerizing a vinyl chloride monomer or a mixture of vinyl monomers containing vinyl chloride monomer as a main component in an aqueous medium,
Chlorination characterized by adding 0.0001 to 0.5 parts by weight of a fluorine-based nonionic surfactant to the polymerization system based on 100 parts by weight of the produced polymer after the polymerization rate reaches 70%. A method for producing vinyl polymer powder.