Thermoplastic Compositions Comprising PVC and Chlorinated Polyethylene

The following examples illustrate the invention.

90 liters of water or of 20% hydrochloric acid respectively were introduced into a 150 liter enamelled vessel, 11,3 kg of polyethylene were added while stirring and the air was evacuated. The suspension then was heated to 70.degree. C. and 5.9 kg of chlorine were added while stirring over a period of 1 to 2 hours while further heating to 90.degree. C. The reaction temperatures then were increased as indicated in the following table and 8.7 kg of chlorine were introduced in the course of 2 and a half hours. After cooling and expanding the reaction mixture was filtered off with suction, washed several times, filtered and dried at 75.degree. C. About 17 kg of chlorination product having the chlorine content indicated in the table were obtained each time.

For determining the transparency 80 parts by weight of S-PVC of a K value of 70 and 20 parts by weight of the various chlorinated polyethylenes were mixed each time while adding 2 parts by weight of dibutyl tin bis-thioglycolic acid octyl ester, rolled at 175.degree. C. for 10 minutes and the plates having a thickness of 4 mm were molded from the rough sheets obtained at a temperature of 180.degree. C. For determining the transparency the portion in percent of passing light rays of a day-light lamp was measured. This portion in percent or directly the light transmittance calculated on PVC (transparency of from 88 to 90%) can be used as a measure for the transparency.

For determining the nothed impact strength according to DIN 53 453 90 parts by weight of S-PVC of a K value of 70 and 10 parts by weight of the various chlorinated polyethylenes were mixed each time while adding 1 part by weight of diphenyl octylphosphite and 3 parts by weight of a complex barium/cadmium stabilizer (consisting of 80% of barium/cadmium laurate, 14% of pentaerythrite and 6% of bisphenol A), rolled as described above and plates of a thickness of 4 mm were molded from the rolled sheets obtained. The required test specimens were prepared from the compressed plates. The following table indicates the results obtained: It can be seen therefrom that an optimal transparency could not be obtained when using a high-density polyethylene having a density of 0.95 g/cm.sup.3 (Examples A and B); the same applies to a high-density polyethylene having a density of 0.96, which had been chlorinated to a chlorine content of 36.1% or 44.8% by weight or to a chlorine content of 39.2% by weight at too high temperatures (Examples C to E). The required properties, i.e., a high residue value and a low swelling value could only be obtained when using under the conditions of the invention the high-density polyethylene having a density of 0.96. Consequently mixtures with PVC may be prepared therefrom, having an excellent transparency and a good impact resistance.

For demonstrating the good light stability 90 parts by weight of S-PVC of a K value of 70 and 10 parts by weight of chlorinated high density polyethylene that had been prepared from a polyethylene of a density of 0.96 g/cm.sup.3, a melting index MFI 190/5 of 48 g/10 min. and a reduced specific viscosity RSV of 1.3 dl/g by chlorination in water in the presence of 0.3% by weight of silicic acid having an average particle size of 12 .mu.m and an inner surface according to BET of 200 cm.sup.2 /g and 0.03% by weight of dimethylpolysiloxane having a viscosity of 1000 centistokes, each time calculated on the quantity of polyethylene an that had a chlorine content of 38.7% by weight, a TAc value of 58% by weight and a MCH value of 0.8% by weight were granulated on the rolls at 170.degree. C. while adding 1.5 part by weight of the complex barium/cadmium laurate stabilizer, 0.5 part by weight of diphenyl phosphite, 2 parts by weight of epoxidized soy bean oil and 1 part by weight of distearylphthalate and injection molded in a 45 extruder, yielding a profile for roller shutters having a thickness of 1 mm. In comparison, the profile prepared from the same S-PVC in the same extruder, but without the addition of chlorinated polyethylene was extruded.

After exposure to light in a fadeometer (carbon filament lamp) for a period of 5000 hours the profile for roller shutters made of the mixture according to the invention did not manifest any discoloration, whereas the profile for roller shutters of pure PVC exhibited a clear tinge of brown.

Polyethylene was chlorinated under the conditions of Examples 1 to 3, but by effecting the total chlorination in one step. The time of chloration was 3 hours.

For determining the transparency it was operated in the manner described in Examples 1 to 3. The results obtained can be seen from the following table.