SU702032A1 - Method of preparing polyvinyl chloride - Google Patents

Description

(54) METHOD OF OBTAINING POLYVINYL CHLORIDE

The invention relates to the field of chemical technology, in particular, to the methods of radical polymerization of vinyl chloride in aqueous suspension. A known method of producing polyvinyl chloride by polymerizing vinyl chloride in an aqueous suspension of fi in the presence of oil-soluble free sweets; bottom radical initiators (azonitriles, peroxides, percarbonate), water-soluble protective colloids (cellulose ethers, polyvinyl alcohol) and alkaline additives by heating the sweets; (the use of a mixture of initiators) and the two-stage ofOF {RI4Peni process of formation with this polyvinyl chloride (PVC) has the properties required for processing and only when the polymer output does not exceed 80%. The closest to the technical essence of this invention is a well-known method of producing polyvinyl chloride suspension polymerization of vinyl chloride in the presence of an oil soluble initiator and a protective colloid. Hydroxypropyl methylcellulose is used as a protective colloid. In order to improve the quality of the polyvinyl chloride obtained, the process is carried out to reduce the pressure by only 0.7 kg / cm2. However, the implementation of this method does not provide deep conversion of vinyl chloride, i.e. a polymer with a low yield is obtained. The purpose of this invention is to increase the yield, increase the decomposition temperature of the polyvinyl-. chloride and reduce the time of absorption of plasticizer. This goal is achieved by the fact that in suspension polymerization of vinyl chloride in the presence of an oil-soluble initiator and protective colloid, a protective colloid selected from the group that includes ammonia-containing graft of hydroxypropylmethylcellulose graft copolymer and vinyl chloride containing 10-15 wt.% Is used as a protective colloid. nitrogen atoms graft copolymer of hydroxypropylmethylcellulose and vinylme. methyl pyrazole or a mixture of grafted co-polymer bxypropylmethylcellulose and inyl methyl pyrazole and hydroxypropylmethylcellulose in as O, 060, 15% of the weight of the aqueous phase in the calculation of the dry dry copolymer or mixture. Graft copolymer and hydroxy-5-propyl methyl cellulose.

Example 1, In a metal reactor capacity. 4 liters, equipped with a 240-rpm root mixer, load 1400 g of the Q aqueous phase containing 3.5 g of paste (concentration of the paste containing ammonia, 24 wt.% Grafted copolymer based on hydroxypropylmethylcellulose and vinyl chloride (0.06 the weight of the aqueous phase (based on the dry graft copolymer, pH of the aqueous phase is 10.4) and 4 g of azo-bis-isobutyronitrile, the reactor is evacuated and injected, 700 g of vinyl chloride. at and pressure of 7.57, 8 kg / cm with continuous nepeMeiimvaniya, complete the polymerization at a pressure of 5.0 kg / cm.

The polymerization duration of 25 vinyl chloride is 4 hours, 45 minutes, the polymer yield is 95.7%, the average particle size is 350 microns, the decomposition temperature is 126 C, the thermal stability at 165 ° C is 60 s, the plasticizer absorption time is dibutyl phthalate (DVF) 10 min., Fraction of polyvinyl chloride (PVC) with apparent density (in ZnC solution) less than 1.15 g / cm, 80 wt.%. 35

When loading 1400 g of an aqueous phase containing 0.84 g of hydroxypropylmethylcellulose powder and 10 g of a 1% solution (also 0.06% by weight,% of bbJf, pH-10.5) The duration of polymerization was 5 hours, the polymer yield was 80 %, the average particle size is 160 microns, decomposition temperature is 124 ° C, thermal stability is 45 s., DBP absorption time is 20 min. PVC fraction with apparent density of 45 less than 1.15 g / cm, 61 wt.%.

Example 2, the same as in example 1, but load 1400 g of water. it contains 8/75 g of a graft copolymer paste based on hydroxyprop p-50 methylcellulose and vinyl chloride (in terms of dry graft copolymer, 0.15 weight,% of aqueous phase, pH-10.7).

. The duration of polymerization 4h 25; min, polymer yield - 81%, 55 average particle size. -164 microns, decomposition temperature -, thermal stability - 56 s, - absorption time of DBP-2 7 min, PVC fraction with a maximum density of less than 1.15 7 / cm 60

54% - -;

When loading the aqueous phase, maintenance. 2.1 g of powdered oxyp ropylmethyl cellulose powder and 10 g of 1% WH-i-OH (also 0.15 weight,% of b-65

The NO phase, 5) the duration of polymerization was 4 hours. 40 minutes; Polymer EXIT: 75%; Average Particle size: 92 microns; decomposition temperature; thermal stability 50 seconds; BpeMJT plasticizer absorption — 38 minutes; PVC fraction with an apparent density less than 1.15 g / cm 11.6 wt.%.

Example 3. Same as in Example D, but 1400 g of an aqueous phase containing 7.0 g of a graft copolymer paste based on hydroxypropylmethylcellulose and vinyl chloride (calculated on a dry graft copolymer of 0.12 wt.% From the aqueous phase, is charged, pH 10.6)

The duration of polymerization, 4.5 hours, the polymer yield is 92%, the average particle size is 260 microns, the decomposition temperature is 133 C, the thermal stability is 70 s, the absorption time of DBP is 14 minutes, the PVC fraction with apparent density less than 1.15 g / cm 78 weight%

. When loading an aqueous phase containing only 1.68 g of hydroxypropylmethylcellulose powder and 10 g of a 1% aqueous solution of NH.i.OH) also 0.12% by weight of the aqueous phase, pH-10.5), the duration of polymerization was 5.0 hours, polymer yield: 78%, average particle size: 140 microns, decomposition temperature, 128 ° C, thermal stability, 55 s., DVF-30 absorption time, PVC fraction with apparent density less than 1.15 g / cm 19 weight%

.Primer 4 ... In a metal reactor capacity of 4. l, equipped with a root agitator (speed 240 rpm), load 1400 g of the aqueous phase, in which 4.95 g of paste are dispersed (concentration 17 wt.%) Graft copolymer of hydroxypropyl methylcellulose and vinyl methyl-pyrazole with a content of 12.6 wt.% Nitrogen atoms in the copolymer (based on dry graft copolymer 0.06 wt.% Of the aqueous phase), 10 g of 1% solution, 4 g of azo-bis-isobutyronitrile, vacuum the reactor and 700 g of vinyl chloride are introduced,

The reaction is carried out at a pressure of 7 / 5-7.8 kg / cm with continuous stirring, complete the polymerization at a pressure of 5 O kg / cm. The polymerization duration of vinyl chloride is 5 hours, the polymer yield is 82%, the average particle size is 320 microns, decomposition temperature is 130 s, thermal stability at 165 C is 70 s, the absorption time of the plasticizer dibutyl phthalate (DBP) is 17 yin, the fraction of polyvinyl chloride (PVC) with apparent density (in solution Znct) is less than .1.15 g / cm 93 wt%. When loading an aqueous phase containing 0.84 g of the powder only oxipromethylcellulose (such 0.06 weight,% of the aqueous phase), the polymerization was 5 hours, the polymer yield 80%, the average particle size 160 microns, decomposition temperature 124 ° C , those stability is 45 s, the absorption time of DBP is 20 min. Fraction of PVC with an apparent density of less than 1.15 K / cm 61 weight,%, P, p and measure 5, Same as in example 4, but load 1400 g of the aqueous phase, in which 9.9 g are pre-dispersed hydroxypropyl methylcellulose grafted copolymer paste and vinyl methyl pyrazole paste (in terms of dry graft copolymer 0.12 wt.% of the aqueous phase). The polymerization time of vinyl chloride is 5.5 hours, the polymer yield is 89%, the average particle size is 190 microns, the decomposition temperature is 135 ° C, the thermal stability is 65 seconds, the absorption time of DBP is 12 minutes, the PVC fraction with apparent density is less than 1, 15 g / cm 90.0 weight,%. When loading an aqueous phase containing 1.68 g of a powder of hydroxypropyl methylcellulose only (also 0.12 wt.% Of the aqueous phase), the polymerization time was 5.0 hours, the polymer yield was 78%, the average particle size was 140 μm, decomposition temperature - 128 ° C, thermal stability -. 55 seconds, the absorption time of DBP is 30 minutes, the PVC fraction with an apparent density of less than 1.15 wt.%. Example 6. Same as in examples 4 and 5, but when loading the aqueous phase containing 3.3 g. Paste graft copolymer based on hydroxypropyl methylcellulose and vinyl-methyl-pi-razola and 0.84 g of hydroxypropyl methylcellulose powder (in terms of on dry graft copolymer and hydroxypropyl methylcellulose 0.1 wt.% of the aqueous phase, the weight ratio of graft copolymer:; hydroxypropyl methyl deamer = 0.4: 0.6), i. The duration of polymerization 5h, the polymer yield is 85%, average

Claims (1)

702032 particle size - 176 microns, decomposition temperature - 133 ° C. thermal stability is 60 s, the absorption time of the DWF is 18 minutes, the PVC fraction with an apparent density of less than 1.15 wt.%. Thus, the method according to the invention allows to increase the yield of polyvinyl chloride by 2-16%, increase the average particle size by 1.5-2 times, reduce the absorption time of the plasticizer and, moreover, increase the decomposition temperature of PVC from 124-127 0 to 130- 135 C. This will lead to a reduction in losses of polyvinyl chloride with exhausts and wastewater and a reduction in the amount of non-polymerized vinyl chloride will improve the conditions of polymer drying, its further processing and working conditions. The method of obtaining polyvinyl chloride by means of suspension polymerization of vinyl chloride in the presence of an oil-soluble initiator and protective colloid, characterized in that, in order to increase the yield, increase the decomposition temperature of the plasticizer, and reduce the absorption time of the plasticizer, the selected colloid was chosen as the protective colloid, the choice of the protective colloid has been chosen as the default colloid containing ammonia paste graft copolymer of hydroxypropyl methylcellulose and vinyl chloride. Containing 10-15 wt.% Nitrogen atoms, graft copolymer of hydroxypropyl methylcellulose and vinyl methyl-pyrazole or a mixture of graft copolymer of hydroxypropyl methylcellulose and vinyl methyl methyl pyrazole and oxyp of eropylmethylcellulose in an amount of 0.06-0.15% by weight of the aqueous phase, calculated on the dry graft copolymer or mixture of graft copolymer and hydroxypropyl, methylcellulose. Sources of information, taken into account in the examination 1. Japanese Patent No. 14437, cl. 26/3 / В 121.5, published. 1973. 2, US Patent 3,716,507, cl. 260-17, published. 1973 (prototype.) .