反应详情

温度

-2 °C

2,683 ml of distilled water, 1,114 ml of a 20% by weight HCl and 1,190 ml of a 19.7% by weight aqueous solution of a fully hydrolyzed polyvinyl alcohol, viscosity 3.68 mPas (DIN 53015; Höppler method; 4% by weight aqueous solution), were charged to a 6 liter glass reactor and cooled to −2° C. within a period of one hour, with stirring. A mixture made from 2.5 g of 3,3-diethoxypropyltriethoxysilane and 188 ml (151.6 g) of butyraldehyde, cooled in advance to −4° C., was then added over a period of 5 minutes, with an attendant rise in internal reactor temperature to −0.7° C. The mixture was then rapidly cooled again to −2° C. 3 minutes after addition of the mixture the reaction mixture, which had until then been clear, was observed to become cloudy, and the product precipitated as little as 5 minutes later. After 40 minutes reaction time at −2° C. the temperature was increased to 25° C. over a period of 3.5 hours, and this temperature was maintained for a further 2 hours. The product was then separated by suction filtration and washed with distilled water until the filtrate gave a neutral reaction. The moist product was dried to a solids content of at least 98%, initially at 22° C. and then at 35° C. in vacuo, yielding a modified polyvinyl butyral having 17.8% by weight of vinyl alcohol units, 1.5% by weight of vinyl acetate units, and 80.7% by weight of vinyl butyral units. The viscosity (DIN 53015; Höppler method; 10% by weight ethanolic solution) was 25.1 mPas. The Si content was determined to be 0.05% by weight.

1. temperaturecooled in advance to −4° C.
2. additionwas then added over a period of 5 minutes, with an attendant rise in internal reactor temperature to −0.7° C
3. temperatureThe mixture was then rapidly cooled again to −2° C
4. addition3 minutes after addition of the mixture the reaction mixture, which
5. customthe product precipitated as little as 5 minutes later
6. customAfter 40 minutes reaction time at −2° C. the temperature
7. temperaturewas increased to 25° C. over a period of 3.5 hours
8. temperaturethis temperature was maintained for a further 2 hours
9. customThe product was then separated by suction filtration
10. washwashed with distilled water until the filtrate
11. customgave
12. customa neutral reaction
13. customThe moist product was dried to a solids content of at least 98%, initially at 22° C.