CS260080B1 - A process for the suspension polymerization and / or copolymerization of vinyl chloride - Google Patents

Abstract

A method of suspension polymerization and/or copolymerization of vinyl chloride, in which a portion of water is first dosed, 2 to 20 wt. % of other polymerization additives and vinyl chloride are added, and then or simultaneously the remaining amount of preheated water with a temperature of 50 to 170 °C is dosed under an overpressure of 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)

Attached Into the reactor with an internal volume of 60 l was added 1.4 l of demineralized water at 18 °C, 19.4 g of dispersants and other components of the polymerization system. The procedure was then carried out according to example 1 with the difference that simultaneously with the addition of 22 kg of VCM at a rate of 0.8 l/min. 26.6 kg of demin. water at 75 °C at a rate of 0.7 l/min. After the addition of hot water was completed, when the temperature in the reactor had risen by 25 °C, the reactor was heated using of the duplicator shell on the polymerization in example 1. temperature 66 °C. The polymerization was terminated as Example 5 The procedure was followed according to example 4, the hot water was started with heating : except, reactor. that at the same time even at the beginning dosage Table Example 1 2 3 4 5 K value ČSN 64 0325 65.3 65.2 60.1 60.2 60.3 bulk weight (g/1) ČSN 64 0804 500 502 623 603 630 remainder for networks - 0.250 (in * according to ČSN 64 0212) 0.3 99 0.1 99 0.3 98 0.2 98 0.4 99 labels (in g) 0.8 0.5 - - - number of fish eyes (pcs/g) according to ČSN 64 3200 - - 1 1 3 BEFORE μ ε τ W I N A I'M CLIMBING 1. Suspension polymerization and/or copolymerization process: First, the material is introduced into the reactor, preferably with stirring. vinyl chloride characterized by 2 to 20% by weight by the total amount of water and other polymerization additives are added, then vinyl chloride is dosed with any other monomers and simultaneously with it or during its dosing, the remaining amount of water is dosed under an overpressure of 0.8 to 1.6 MPa, preheated to a temperature of 50 to 170 °C. 2. The method according to item 1, characterized in that the reactor is finally heated to the polymerization temperature. 3. The method according to item 1 and/or 2, characterized in that the additional heating of the reactor to the polymerization temperature is started after the start of dosing the remaining amount of water heated to a temperature of 50 to 170 °C.