METHOD FOR MULTIPLE LAYER COEXTRUSION USING AN INTERMEDIATE DUCTILE LAYER

摘要

The invention relates to a method for protecting a thermoplastic polymer, whereby the following layers are superimposed by coextrusion, hot-pressing or multi-injection, in the following order: a) a protective layer (I) comprising a PMMA having a fissuring time in accordance with the conditions of the EN 13559 norm which is higher than 2 minutes, or b) a mixture comprising between 90 and 99.9 wt. % of a PMMA and between 0.1 and 10 wt. % of a PVDF, or c) an acrylic copolymer comprising between 80 and 99.8 wt. % of methyl methacrylate (MMA), between 0 and 20 wt. % of at least one comonomer that can be copolymerised with the MMA, and between 0.2 and 10 % of acrylic acid and/or methacrylic and/or maleic anhydride and/or anhydride groupings of formula (I) wherein R1 and R2 are H or a methyl radical, the total amounting to 100 %; an intermediate ductile layer (II) comprising a sequenced copolymer of formula BAn consisting of a polymer sequence B comprising at least 60 wt. % of at least one (meth)acrylic monomer having a Tg lower than -5°C, and n polymer sequences A which are connected to the polymer sequence B by covalent bonds, n representing an integer between 1 and 10, and comprise at least 60 wt. % of at least one (meth)acrylic monomer having a Tg higher than 0°C, such that sequence B and/or sequences A comprise between 0.2 and 20 wt. % of at least one compound selected from acrylic acid, methacrylic, styrene, alphamethyl styrene, maleic anhydride, acrylonitrile, glycidyl acrylate, and glycidyl methacrylate; and a layer of at least one thermoplastic polymer (III).