Polyethylene or polypropylene modified with an acrylic - monomer to improve dye receptivity

Olefin-acrylate copolymer is produced by (i) forming a crystalline polyethylene, polypropylene or propylene-ethylene random or block copolymer contg. less than 30 wt.% ethylene units, (2) adding an alkyl lithium catalyst and an acrylic monomer CH2 = C(R')COOR2 and (3) copolymerising the monomer on to the solid olefin polymer. R' is H or CH3 and R2 is an alkyl, alkylaminoalkyl or alkoxyalkyl group. Presence of the acrylic units in the copolymer enhances the receptivity of the olefin polymer to colourants and the copolymer can be found into fibres having excellent dyeability. Acrylic monomer suitably forms 0.1-10% by wt. of the copolymer but even the presence of 0.1-1% by wt. of copolymerised acrylic monomer imparts increased dye receptivity. The pref. monomers are the 1-6 C alkyl esters. The pref. Li catalyst is BuLi and it is preferably used in conjunction with an organo-metallic catalyst; the latter can be brought forward by the olefin polymer from step 1. Step 3 is carried out at a temp. from -50 degrees to +150 degrees C.