CS260080B1 - Method of vinyl chloride suspension polymerization and/or copolymerization - Google Patents

Abstract

Suspension polymerization process and / or copolymerization of vinyl chloride in which a portion of Water, 2 through 20 wt. add other polymerization additives and vinyl chloride and then or simultaneously the remaining amount of preheated is dosed water at 50-170 ° C under positive pressure 0.8 to 1.6 MPa.

Description

The present invention relates to a process for the suspension polymerization and / or copolymerization of vinyl chloride (VCM).

The VCM suspension polymerization is carried out batchwise on a production scale. Usually, the necessary ingredients such as dispersants, surfactants and the like are metered into the polymerization reactor with the present water, the polymerization initiator and monomer vinyl chloride are added. Thereafter, or during VCM dosing, the reactor is heated to the polymerization temperature (jacket heating or direct steam heating), and the polymerization itself occurs. The described process has relatively low productivity. One limiting factor is the long heating time of the reactor.

The above-mentioned disadvantages are overcome by the process for the suspension polymerization and / or copolymerization of vinyl chloride according to the invention, which consists in first adding to the polymerization reactor 2 to 20% by weight of the total amount of water with stirring and adding other polymerization additives. VCM, event. the remaining amount of water under a positive pressure of 0.8 to 1.6 MPa preheated to a temperature of 50 to 170 [deg.] C. is added simultaneously with the commencement of dosing of the monomer, possibly only during its dosing. If necessary, the reactor is heated to polymerization temperature. At the same time, it is possible to start heating it after the hot water dosing has started.

The main advantage of the process according to the invention is a significant shortening of the polymerization cycle and thus a substantial increase in the productivity of the whole process. In addition, the process of the invention results in energy savings and reduced reactor sticking while maintaining the quality of the final product. Waste heat can be advantageously used to preheat the water.

The following examples illustrate the process of the invention. The first example describes the prior art, given for comparison.

Example 1

Into an 8 liter reactor equipped with a stirrer and a duplicator was charged 4,200 g of 20 ° C aqueous phase containing demineralized water with 3.4 g of a mixture of methylhydroxypropylcellulose and hydroxypropylcellulose. In addition, the other components needed for the polymerization mixture and the initiators were added. The reactor was sealed and evacuated to 1.866 kPa after flushing the free space with nitrogen. 2400 g of vinyl chloride were metered in with stirring.

After the VCM dosing was complete, the reactor was heated to a polymerization temperature of 59 ° C using a duplicator jacket. The polymerization was terminated after a pressure drop of 0.2 MPa, cooling of the reactor and evaporation of unreacted monomer.

Example 2

500 ml of 20 ° C warm demineralized water, 3.4 g of cellulose derivatives (dispersants) were charged to an 8 liter internal reactor. The procedure of Example 1 was followed except that at the same time as 2400 g of VCM (80 ml / min.) Was dosed, 3,700 g of water 80 ° C were fed into the reactor at a warm rate of 160 ml / min. After the hot water was metered in, when the temperature in the reactor rose by 23 ° C, heating was started with a duplicator reactor jacket to a polymerization temperature of 59 ° C. The polymerization was terminated as in Example 1.

Example 3

To a 60 liter internal reactor equipped with a stirrer and a duplicator was charged 28 kg of demin. water, 2? kg VCM, 19.4 g dispersants and other components of the polymerization system. The procedure of Example 1 was followed except that the polymerization temperature was 66 ° C.

Claims (3)

He attaches A 60 L reactor was charged with 1.4 L of 18 ° C warm water, 19.4 g of dispersants and other components of the polymerization system. The procedure of Example 1 was followed with the difference that at the same time a dosage of 22 kg of VCM was applied at a rate of 0.8 l / min. 26.6 kg of demin was metered into the reactor. water 75 ° C warm rate 0.7 l / min. After completion of the hot water dosing, when the temperature in the reactor rose by 25 ° C, the reactor was heated with Duplicator sheath for polymerization in Example 1. 66 ° C. The polymerization was terminated as well Example 5 Example 4 hot water was started and heating was started : with the difference, reactor. that at the same time and the beginning dosage Table Example 1 2 3 4 5 K value CSN 64 0325 65.3 65.2 60.1 60.2 60.3 bulk density (g / 1) CSN 64 0804 500 502 623 603 630 net rest - 0,250 (in * according to ČSN 64 0212) 0.3 99 0.1 99 0.3 98 0.2 98 0.4 99 stickers (in g) 0.8 0.5 - - - number of fish eyes (pcs / g) according to ČSN 64 3200 - - 1 1 3 BEFORE μ ε τ V Y N A LEZU The slurry polymerization and / or copolymerization process is first introduced into the reactor, preferably with stirring vinyl chloride labeled 2 to 20% by weight that total the amount of water and other polymerization additives are added, then vinyl chloride is added, optionally with the addition of water. with the remaining monomers and at the same time as or during the dosing thereof, the remaining amount of water is metered under a pressure of 0.8 to 1.6 MPa preheated to a temperature of 50 to 170 ° C. 2. Process according to claim 1, characterized in that the reactor is finally heated to the polymerization temperature. 3. A process as claimed in claim 1 and / or 2, characterized in that the additional heating of the reactor to the polymerization temperature is started after the start of dosing of the remaining amount of water heated to a temperature of 50 to 170 [deg.] C.