Patent ID: 6544453
Filing Date: 2003-04-08
Classification: C08L

Abstract:
A process for preparing a shaped article of a crosslinked polymer, the process comprising(A) placing in a mold a composition which comprises (1) a matrix material which (a) provides a continuous phase and (b) comprises at least one precursor which will react to form a crosslinked polymer; and (2) a low profile additive (LPA) which (a) comprises a crystalline polymer having an onset of melting temperature To and a peak melting temperature Tp which is (i) at least 30Â° C., and (ii) such that Tpâˆ’To is less than Tp0.7, at least 10% by weight of the crystalline polymer being in the form of solid particles which are free of any material which takes part in the reaction which forms the crosslinked polymer, and (b) is in the form of particles which are uniformly suspended in the matrix material; (B) maintaining the composition in the mold at a temperature which is greater than Tp and for a time such that the precursor reacts to form the crosslinked polymer; and (C) cooling the product of step (B) to obtain the shaped article of the crosslinked polymer; the composition and the process conditions being such that the shaped article has a shrinkage which is at least one of (i) a shrinkage of less than 5%, and (ii) a shrinkage which is less than 0.5 times the shrinkage of a shaped article prepared in the same way from a reaction mixture which is the same except that it does not contain the LPA.