CS260081B1 - Method of vinyl chloride suspension polymerization and/or copolymerization - Google Patents

Abstract

Suspension polymerization process and / or copolymerization of vinyl chloride in which First, polymerization additives are dispensed adds vinyl chloride along with some water 2 to 20 wt. and finally adds the remaining amount of preheated water at temperature 50 to 170 ° C under a pressure 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).

VCM suspension polymerization is carried out batchwise on an industrial 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 the VCM dosing, the reactor is heated to the polymerization temperature (heating is carried out by jacket or directly by steam) and the polymerization itself takes place. 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, with stirring, polymerization additives and other components together with a small amount of water, i.e. water, and VCM with event. and then the remainder of the water is metered in under a positive pressure of 0.8 to 1.6 MPa, preheated to a temperature of 50 to 170 ° C. If necessary, the reactor is further heated by the jacket to the polymerization temperature. At the same time, it is possible to start by heating the reactor jacket as soon as hot water is added.

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 sticking in the reactor while maintaining the quality parameters 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 the 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 then metered in with stirring.

After the vinyl chloride dosing was completed, 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

A 500 ml reactor was charged with 500 ml demin. water 20 ° C warm,

3.4 g cellulose derivatives (dispersants). The procedure of Example 1 was followed, except that after feeding 2,400 g of VCM, 3,700 g of water at 82 ° C were charged into the reactor under a pressure of 1.25 MPa. When the 3500 g of water was metered in, when the temperature in the reactor rose by 21 ° C, heating was started with a duplicator reactor jacket to a polymerization temperature of 59 ° C.

The procedure of Example 1 was followed.

Example 3

The procedure is the same as in Example 2 except that the reactor jacket was brought to 58 ° C (i.e. 1 ° C below the polymerization temperature of 59 ° C) at the start of the 80 ° C warm water feed.

During dosing, the reactor temperature rose by 27 ° C and the reactor temperature was adjusted to 59 ° C. The procedure is the same as in Example 1.

and

Example 4

The procedure was as in Example 2, with the difference that after dosing 1/2 amount (i.e. about 1800 g) 75. The warm water C was started with reheating with the reactor jacket.

Example 5

A 28 L reactor equipped with a stirrer and a duplicator was charged with 28 kg of demin. water, 22 kg VCM, 0.019 4 kg dispersants and other components needed for the polymerization mixture as described in Example 1 except that the polymerization temperature was 66 ° C.

Example 6

A 60 L reactor was charged with 1.4 L of 18 ° C warm water, 0.019 kg of dispersants and other components of the polymerization system. The procedure was as in Example 1, except that after dosing 22 kg of VCM, 26.6 kg of demin was fed into the reactor at a rate of 0.7 l / min. water 75 ° C warm under pressure 1.5 MPa. After the hot water dosing was completed when the reactor temperature increased by 25 ° C, the reactor was heated to 66 ° C by means of a reactor jacket. The polymerization was terminated according to Example 1.

Table

Example 1 2 3 4 5 6 K value 65.5 65.3 65.2 according to CSN 64 0325 65.4 60.1 60.2 SH (g / D 545 541 loose 527 531. weight according to CSN 64 623 0804 627 0.250 (%) sifter 0.5 0.5 tracks 0.1 0.3 0.5 0.063 (») 90 97 residue 97 on networks o 98 98 of the given mesh size 98 64 CSN 0212 stickers (g) 0.7 0.3 0.4 0.4 - - RO (pcs / g) - number fisheye mesh 'according to CSN 2 64 3200 2

SUBJECT OF THE INVENTION

Claims (3)

A process for the suspension polymerization and / or copolymerization of vinyl chloride, characterized in that first the polymerization additives, then the other components together with 2 to 20% by weight of the total amount of water and vinyl chloride with a possible addition of 2 to 20 wt. and then the remainder of the water is metered under an overpressure of 0.8-1.6 MPa preheated to 50-170 ° 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 or claim 2, characterized in that the additional heating of the reactor to the polymerization temperature is initiated after the start of dosing of the remaining amount of water heated to 50-170 [deg.] C.