Patent ID: 8163810
Filing Date: 2012-04-24
Classification: C08J,G02B

Abstract:
1. A method for substantially diminishing or essentially eliminating a visible knitline in an article derived from a resinous composition comprising (A) at least one thermoplastic resin selected from the group consisting of acrylonitrile-butadiene-styrene terpolymers (ABS), acrylate-modified ABS, acrylonitrile-styrene-acrylate terpolymers (ASA), methyl methacrylate-modified ASA, blends comprising at least one of these resins, ABS blends with polycarbonate, acrylate-modified ABS blends with polycarbonate, ABS blends with PMMA, acrylate-modified ABS blends with PMMA, ABS blends with SAN, acrylate-modified ABS blends with SAN, ASA blends with polycarbonate, methyl methacrylate-modified ASA blends with polycarbonate, ASA blends with PMMA, methyl methacrylate-modified ASA blends with PMMA, ASA blends with SAN, and methyl methacrylate-modified ASA blends with SAN; and (B) at least one special visual effect additive present in a range of between about 0.005 parts per hundred parts resin by weight (phr) and about 25 phr, selected from the group consisting of glass flakes, metallic pigments, metal flakes, aluminum pigment, crosslinked polymer particles, crosslinked acrylic resin, and mixtures comprising at least one of such additives, which comprises the steps of (i) including in the composition at least one chemical foaming agent selected from the group consisting of natural carbonates, natural bicarbonates, calcite, calcium carbonate, sodium bicarbonate, lithium carbonate, zinc carbonate, synthetic carbonates, dihydroxyaluminum sodium carbonates, dihydroxyaluminum calcium carbonates, aluminum hydroxide magnesium carbonates, and mixtures thereof, and (ii) forming the article in a process that produces a knitline, wherein the amount of chemical foaming agent is effective to provide a molded article having a surface gloss value greater than about 80%, wherein the gloss value exhibits less than 8% standard deviation and less than 16% decrease in value measured at an angle of 60 degrees according to ASTM D 523 compared to the gloss value measured on a similar molded article of a composition not containing chemical foaming agent, and wherein the article exhibits a substantially diminished or essentially no visible knitline compared to a similar article prepared without chemical foaming agent.