DE744401C - Process for the production of polyvinyl chloride with a low degree of polymerization - Google Patents

Description

Process for the production of polyvinyl chloride with a low degree of polymerization The polymerization of vinyl chloride in aqueous emulsion is known. One works usually at temperatures of about 5o ° and then receives a plastic, its degree of polymerization according to F i k e n t -s c h e r (magazine for cellulose chemistry, Vol. I3, t932, p.6o) is about 6oK (K = k.io3). Even if plastics with this degree of polymerization are well suited for most processing purposes, there is for certain Special areas, for example the production of spray or high-gloss polish paints, the need to also produce polyvinyl chloride with a significantly lower K value, from .dem therefore low-viscosity solutions can be produced.

Although it is already a polyvinyl chloride mixes relatively good Solubility in e.g. toluene became known. This was made by polymerization in obtained an organic solvent at elevated temperature, with the addition of cumbersome way of working, a discoloration of the end product is accepted had to become.

It has also been proposed to polymerize vinyl chloride in an aqueous emulsion with the addition of an emulsifying agent in order to obtain an end product that is as highly polymeric as possible. In this case, also a number of organic compounds are, inter alia, hydrocarbons or their chlorination products, zuesetzt, influence the emulsion formation TO '.

As has now been found, polyvinyl chlorides with a K value of about 28 can be prepared by the emulsion polymerization process if vinyl chloride is used in the presence of small amounts of a non-polymerizable aliphatic, low. Molecular chlorinated hydrocarbons and gasoline "polymerized in aqueous emulsion. The use of gasoline has the advantage that an undesirably high increase in pressure is avoided, so that the highly exothermic polymerization can always be monitored well..: As Emulsifiers and as Katall. @ # I. Clays can be used for this @wel ':,;? a stabilizer, for example sodium phosphate, is added to the emulsification mixture i% hydrogen peroxide, based on water, are 5o kg together with 5l, Vinylchlo.rid - emulsifying a mixture comprising Tetrachlorkohlenstofi and petrol having a boiling point 55 to 65 'in the ratio 3: 1 contains This emulsion is on in a pressure vessel;.. o Heated to 75 'in order to get the reaction going (duration of the reaction q. up to 5 hours), with a pressure of up to 15 atin. occurs. The modified vinyl chloride and the added chlorinated hydrocarbon and gasoline are then removed from the reaction mixture by evaporation. A solid polyvinyl chloride in extremely finely divided state, the degree of polymerization of which corresponds to a K value of about 3 °, is obtained in a yield of 80 to 850%.

Of course, you can also carry out the polymerization in the flow tube perform continuously.

Claims (1)

PATEN TAN SPRTJCH Process for the production of polyvinyl chloride low degree of polymerization, characterized in that vinyl chloride is polymerized in the presence of small amounts of a non-polymerizable aliphatic, low molecular weight chlorinated hydrocarbon and of gasoline in an aqueous emulsion: To distinguish the subject of the application from the prior art are in The following publications have been taken into consideration for the granting procedure: French patent specifications No. 773220, 801 03: 1; British patent specification ...... - 349499