Method for producing castings by activated anionic polymerizatio

Details Method for producing castings by activated anionic polymerizatio Method for producing castings by activated anionic polymerizatio

1977-07-21

1980-01-08

Thurlow, Jeffery R.

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From carboxylic acid or derivative thereof

264102, 264331, C08G 6944

Patent

active

041828437

ABSTRACT:
An improved method for the production of castings by the anionic polymerization of lactams, particularly lauric lactam, in which two melts prepared separately, one with a catalyst and one with an activator, are polymerized together in a mold heated to substantially the same temperature as the melts, is described, the improvement comprising the application of a vacuum in the range from about 80 to 450 Torr, said vacuum being selected in accordance with the formula S.times. T= K where S is the surface area of the casting exposed to the vacuum, V is the volume thereof, T is the vacuum application time and is less than the polymerization time and K is a constant. Said vacuum is replaced by ambient pressure either progressively or instantaneously when the polymerization mixture reaches a highly viscous non-stirrable state. Thereafter, the polymer may be heat treated at a temperature about 10.degree. to 20.degree. C. below its crystallization melting range if desired during completion of the polymerization to inhibit the formation of shrinkage blow holes. The mold is preferably gas-tight.

REFERENCES:
patent: 2735840 (1956-02-01), Lynch
patent: 2867805 (1959-01-01), Ludewig
patent: 3494999 (1970-02-01), Heckrotte
patent: 3505448 (1970-04-01), Zijp et al.
patent: 3551541 (1970-12-01), Rossetti
patent: 3551552 (1970-12-01), Opalewski
patent: 3658975 (1972-04-01), Drabek et al.
patent: 3752623 (1973-08-01), Sinn et al.

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