Thermoplastic moulding compositions reinforced with a mixture of glass and asbestos fibers

Abstract

Thermoplastic compositions comprise a thermoplastic polymer and are reinforced by a mixture of asbestos fibres and glass fibres. The compositions may be granular moulding compositions or moulded articles.

We claim: 
     
       1. A .Iadd.granular .Iaddend.thermoplastic .Iadd.molding .Iaddend.composition, comprising (i) from 60 to 90 percent by weight of a thermoplastic polymeric material selected from the group consisting of polyolefins, polystyrene, polyamides, copolymers of butadiene, copolymers of acrylonitrile and copolymers of styrene; (ii) at least 10 percent by weight, based on the total weight of the composition, of a mixture of glass fibres and asbestos fibres in a weight ratio of from 1:0 11 to 1:9; and (iii) from zero to 20 percent by weight based on the polymeric material of a component selected from the group consisting of fillers and additives other than glass fibres and asbestos fibres; said ratio of glass and asbestos fibres .[.lending.]. .Iadd.being selected to impart .Iaddend.synergistic properties to .Iadd.an article injection molded from .Iaddend.the .Iadd.granular .Iaddend.thermoplastic molding composition in at least one of the properties of tensile strength, flexural strength, tensile modulus and flexural modulus  .Iadd.of the article. .Iaddend. 
     
     
       2. A .Iadd.granular .Iaddend.thermoplastic .Iadd.molding .Iaddend.composition according to claim 1, wherein the weight ratio of glass fibres to asbestos fibres is within the range from 1:1 to 1:9. 
     
     
       3. A .Iadd.granular .Iaddend.thermoplastic .Iadd.molding .Iaddend.composition according to claim 1, wherein the asbestos fibres comprise essentially asbestos of grades 4, 5 6 6 of the Canadian Classification. 
     
     
       4. A .Iadd.granular .Iaddend.thermoplastic .Iadd.molding .Iaddend.composition according to claim 1, in which the weight of said polymeric material is from 60, to 80 percent and in which the weight ratio of glass fibres to asbestos fibres is from 3:7 to 7:3. 
     
     
       5. A method of manufacturing the .Iadd.granular .Iaddend.thermoplastic .Iadd.molding .Iaddend.composition as claimed in claim 1 .[.in the form of a granular moulding material.]., comprising compounding together (i), (ii) and (iii) as described in claim 1 at a temperature above the softening point of the polymeric material, extruding the resulting compounded composition and granulating the extrudate so formed.