SU810726A1 - Method of preparing polyvinyl chloride - Google Patents

Description

one

The invention relates to chemical technology, in particular to methods for the radical polymerization of vinyl chloride in aqueous suspension.

A method of producing polyvinyl chloride by suspension polymerization of vinyl chloride in the presence of an oil-soluble initiator and cellulose ether as a protective colloid 1 is known.

However, in order to improve the quality of the polyvinyl chloride produced, the process is carried out until the pressure is reduced by only 0.7 kg / cm, which does not provide a deep conversion of vinyl chloride, i.e. a polymer with a low yield is obtained.

The closest to technical sushi, post-invention, method of producing polyvinyl chloride by suspension polymerization of vinyl chloride in the presence of a self-soluble initiator, simple cellulose, and addition of ammonia water to the aqueous phase 2.

However, to obtain a porous and granulometrically homogeneous polyvinyl chloride, an additional organophilic emulsifier is used, the preparation of which represents a preliminary stage of the process, which complicates the technology for producing polyvinyl chloride.

The aim of the invention is to elucidate polyvinyl chloride with increased granulometric and morphological uniformity, decomposition temperature and thermal stability.

The goal is achieved by the fact that according to the method of producing polyvinyl chloride by suspension polymerization of vinyl chloride in the presence of an oil-soluble initiator, cellulose ether and addition of ammonia water, the vinyl chloride is subjected to polymerization, containing 0.005-0.03% by weight of ammonia monomer.

The dryness of the proposed method is illustrated by examples.

Claims (2)

Example 1. In an industrial autoclave with a capacity of 14 m equipped with a propeller agitator with breakwaters (183 rpm) and an automatically controlled cooling-heating system, 7200 kg of demineralized water is loaded. 1.8 kg of inethocel protective colloid - 65--11G-50, 2.5 kg of 25% ammonia water and 5.0 kg of azodiisobutyronitrile initiator. Autoclave vacuum load 4600 kg of vinyl chloride, which contains ammonia in the amount of 0.005 weight. %, turn on the stirrer and carry out the process at 5PC and pressure of 7.4 kg / cm. When the pressure drops to 5 kg / cm, the autoclave is cooled down, residual vinyl chloride is blown off (92% monomer conversion), the suspension is squeezed out in a centrifuge, from which a sample is taken. The properties of the obtained polymer are listed in the table. Example 2. The process is carried out as in Example 1, but 4600 kg of vinyl chloride is loaded, which contains ammonia in an amount of 0.03 weight. %, turn on the stirrer and carry out the process at 51 ° C and a pressure of 7.1 kg / cm. When pressure is applied up to 5 kg / cm, the autoclave is cooled down, residual vinyl chloride is blown out (monomer conversion is 91%), the suspension is drained in a centrifuge, from which a sample is taken. Properties of the obtained polymer are given in table. Example 3. The process is carried out as in Example 1, but 4600 kg of vinyl chloride is loaded, which contains ammonia in an amount of 0.01 wt. %, turn on the stirrer and carry out the NPP process of 51 ° C and a pressure of 7.4 kg / cm. When the pressure drops to 5 kg / cm: the autoclave is chilled, residual vinyl chloride is blown out (92.5% monomer conversion), the suspension is squeezed out in a centrifuge, from where the nrob is taken. Properties of the obtained polymer are shown in the table. Example 4. The process is carried out as in Example 1, but 4600 kg of vinyl chloride is loaded, which contains ammonia in an amount of 0.02 weight. %, turn on the agitator and carry out the process at 5 gs and a pressure of 7.4 kg / cm. When the pressure drops to 5 kg / cm-the autoclave is cooled down, residual vinyl chloride is blown out (92% monomer conversion), the suspension is squeezed out in a centrifuge, from which a sample is taken. Properties of the obtained polymer are shown in the table. The method of obtaining polyvinyl chloride with the use of vinyl chloride, in which ammonia is pre-introduced in quantities of 0.005-0.03 weight. % in comparison with the method in which ammonia is supplied only to the aqueous phase, leads to an increase in the decomposition temperature and thermal stability of the polymer by 19-27 ° C and 1.3-3.3 times, respectively. Polyvinyl chloride has a narrow particle size distribution, and the content of large fractions increases and the content of small fractions sharply decreases, and the average particle size increases. The polymer has a high morphological uniformity - the content of the fraction with an apparent density in an aqueous solution of less than 1.05 g / cm increases 3 times or more. At the same time, the stabilization of the pH during the polymerization process is maintained by ammonia water added to the aqueous phase. The method will allow to reduce the loss of polyvinyl chloride with exhausts and wastewater - oo o 01 h with ET y 1L cG - .d 00 LO-ILO mi: with 00 m - J x oo a 00 o 003 t1- with t} - o оо сС -Ч со - м t LO со 1 О) о - о со о о о о о о о о о tо Ф о оо о со соо - со Tf со -. о о о 10 Tt - «D о о о о t t §§§ оо о о о со - sm 000 m, with s, improve the conditions of drying and subsequent processing of the polymer. Thus, the invention makes it possible to obtain polyvinyl chloride with increased particle size and morphological uniformity, decomposition temperature, and thermal stability. The invention The method of producing polyvinyl chloride by suspension polymerization of vinyl chloride in the presence of an oil-soluble initiator, cellulose ether and addition of ammonia water, from l and 5 to 10, is due to the fact that, in order to obtain a polyvinyl chloride with an increased granulometric and morphological uniformity, temperature, decomposition, temperature, decomposition, and decomposition of the granulometric and morphological uniformity of temperature. polymerization is subjected to vinyl chloride containing 0.005-0.03% by weight of ammonia monomer. Sources of information taken into account in the examination 1. US patent number 3716507, cl. 260-16, published. 1973. 2. The patent of Switzerland No. 538575, cl. C 08 F 1/4, publ. 1973 (prototype).