Process for preparing cellulose pulp filler for thermosetting resin molding powders

Abstract

A process is provided for preparing a graft polymermodified cellulose pulp filler from cellulose sulfite pulp having an R.sub.18 value greater than 80%, which comprises adding to the pulp a redox initiator; washing the pulp with water having a pH below 5 in an amount sufficient to adjust the redox initiator cation content to within the range from about 5 to about 1000 ppm of cellulose sulfite pulp; adding hydrogen peroxide in an amount to provide within the range from about 0.1% to about 4% H.sub.2 O.sub.2 by weight of the sulfite pulp; and then reacting the pulp with at least one monomer having the formula: ##STR1## in which: R.sub.1 is hydrogen or methyl; and R.sub.2 is selected from the group consisting of nitrilo --CN, ##STR2## and COOR.sub.3 groups, wherein R.sub.3 is selected from the group consisting of methyl, ethyl, n-butyl, isobutyl and 2-ethylhexyl; at a temperature at which grafting of the monomer onto the cellulose polymer molecule proceeds but below about 70.degree. C. for a time less than twelve hours under an inert atmosphere in a grafting ratio within the range from about 1 to about 40% and an average degree of polymerization within the range from about 20 to about 4000; and then recovering the graft polymer-modified cellulose sulfite pulp. The resulting cellulose pulp is adapted for use as a filler for thermosetting resins, imparting to the resins increased impact strength and structural strength, improved resistance to heat distortion and shrinkage, and decreased water absorptivity.

Dependencies are inferred from the claim text.