Thermoplastic composite
The invention relates to multi-layer thermoplastic composites, and in particular composites having fluoropolymer in the outer layer and a thermoplastic substrate layer. The fluoropolymer outer layer may either be a layer comprising a majority, and preferably 100 percent fluoropolymer, or may be a blend of a thermoplastic matrix with fluoropolymer at a level of from 5 to 60 weight percent, based on the total weight of all polymers. Especially useful thermoplastic matrices include acrylic polymers, and styrenic polymers, especially styrenic copolymers such as acrylonitrile/styrene/acrylate (ASA), acrylonitrile/butadiene/styrene (ABS) and styrene/acrylonitrile (SAN). While the fluoropolymer may be any fluoropolymer, thermoplastic fluoropolymers, such as polymers and copolymers of polyvinylidene fluoride are especially useful. The improved flame retardant composite of the invention is especially useful in cap layers over plastic substrates, such as for flame-retardant plastic decking, railings, posts, fencing, siding, roofing, and window profiles.
1. A multilayer composite comprising a capstock containing a styrenic polymer, and a fluoropolymer, over a substrate layer, wherein said fluoropolymer is in the outermost layer of the composite wherein said multilayer composite consists of either:
a) a 2-layer composite having an outer layer comprised of a blend of 5 to 49 weight percent fluoropolymer and 51 to 95 weight percent of styrenic polymer, based on the total weight of the polymer blend, over a substrate; or
said styrenic polymer(s) being selected from the group consisting of polystyrene, high-impact polystyrene (HIPS), acrylonitrile-butadiene-styrene (ABS) copolymers, acrylonitrile-styrene-acrylate (ASA) copolymers, styrene acrylonitrile (SAN) copolymers, copolymers, styrene-butadiene copolymers (SB), styrene-butadiene-styrene block (SBS) copolymers and their partially or fully hydrogenenated derivatives, styrene-isoprene copolymers styrene-isoprene-styrene (SIS) block copolymers and their partially or fully hydrogenated derivatives, and mixtures thereof, and wherein said substrate is a thermoplastic material selected from the group of polyvinyl chloride (PVC), acrylonitrile-butadiene-styrene (ABS), polyolefins (polypropylene, polyethylene, copolymers and mixtures thereof), polycarbonate (PC), polyurethane (PU), and mixtures thereof,
wherein said multi-layer structure is flame retardant as determined by one or more tests selected from the group consisting of a) obtaining a NFPA rating of at least one Class higher than a multi-layer structure of the same composition but without the fluoropolymer added, when tested by ASTM E84 flame test, b) obtaining a NFPA “A” or “B” rating when tested by the ASTM E84 flame test, c) obtaining a UL-94 rating of at least one Class higher (V0, V1, V2) than a multi-layer structure of the same composition but without the fluoropolymer added, when tested by UL-94 flame test, and d) obtaining a “V0” rating when tested by the UL-94 flame test.
2. The composite of claim 1 , wherein said fluoropolymer is present at from 10 to 40 weight percent and said styrenic polymer is present at from 60 to 90 weight percent.
3. The composite of claim 1 wherein said fluoropolymer is a copolymer of vinylidene fluoride and hexafluoropropene.
4. The multi-layer composite of claim 1 , wherein said PVC substrate is filled polyvinyl chloride, or foamed polyvinyl chloride.
5. The multi-layer structure of claim 1 , wherein said multi-layer structure is in the form of decking, a railing, a post, fencing, a roofing product, siding, or a window profile.