Multilayer composite
View Patent ↗The invention relates to multilayer composites having improved weathering properties without reducing flame retardation properties. The composites have a fluoropolymer layer over a thermoplastic layer. The multilayer composite may be a fluoropolymer layer directly over a relatively flammable substrate or non-flammable substrate (like PVC), or it may be a fluoropolymer layer over a relatively flammable cap layer, over a substrate (that is flammable or non-flammable). The composite is formed using coating, coextrusion and/or lamination techniques. The multilayer composite is especially useful in articles having surfaces that are used in a relatively horizontal position, including decking, railings, roofing and window profiles. The composites provide improved weathering for the substrate without a reduction in flame-resistance, when compared to the substrate without the outer fluoropolymer layer. The multi-layer composite also provides enhanced chemical resistance, hardness, scratch and mar, and water resistance.
1. A weatherable multilayer composite comprising, in order:
a) an outer fluoropolymer layer having a thickness of from 0.01 to 0.2 mm, comprising at least 85 weight percent of a polyvinylidene fluoride homopolymer, or a polyvinylidene fluoride copolymer comprising at least 70 weight percent of vinylidene fluoride monomer units, and less than 15 weight percent of other compatible polymers,
b) an intermediate flammable thermoplastic polymer cap layer having a thickness of from 0.5 to 2.5 mm, selected from the group consisting of acrylic and styrenic polymers, and
c) a thermoplastic substrate layer having a thickness of from 1.0 to 50 mm.
2. The weatherable multilayer composite of claim 1 , wherein said intermediate layer comprises a acrylonitrile-styrene-acrylate (ASA) copolymer.
3. The weatherable multilayer composite of claim 2 , wherein said intermediate layer comprises an alloy of ASA and a polyvinyl chloride polymer.
4. The weatherable multilayer composite of claim 1 , wherein said fluoropolymer layer comprises two or more fluoropolymer layers, the layers having the same or different compositions.
5. The weatherable multilayer composite of claim 1 , wherein said polyvinylidene copolymer comprises from 1 to 30 weight percent of hexafluoropropylene.
6. The weatherable multilayer composite of claim 1 , wherein said substrate is selected from the group consisting of acrylic polymers, styrenic polymers, polyolefins, polyvinyl chloride (PVC), polycarbonate (PC), polyurethane (PU), and mixtures thereof.
7. The weatherable multilayer composite of claim 1 , wherein said acrylic polymer is a polymethyl methacrylate homopolymer or a copolymer comprising at least 70 weight percent of methyl methacrylate units.
8. The weatherable multilayer composite of claim 1 , wherein said thermoplastic polymer layer is pigmented.
9. The weatherable multilayer composite of claim 1 , wherein said outer fluoropolymer layer comprises greater than 95 weight percent fluoropolymer.
10. The weatherable multilayer composite of claim 9 , wherein said outer fluoropolymer layer comprises 100 weight percent fluoropolymer.