Stock material or miscellaneous articles – Composite
Reexamination Certificate
2001-01-26
2003-12-23
Zacharia, Ramsey (Department: 1773)
Stock material or miscellaneous articles
Composite
C428S421000, C428S475800, C428S476100, C428S476300, C428S476900, C428S480000, C428S483000, C428S500000, C428S516000, C428S519000, C428S520000, C428S521000, C428S522000, C428S523000, C428S914000
Reexamination Certificate
active
06667101
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a thermoformable multilayer film for the protection of substrates and to the objects thus obtained.
Use is made, particularly in the motor-vehicle industry, of many body components made of plastic, such as bumpers, wing mirrors, the bonnet and increasingly all the other components such as the doors and wings. These components have the advantage of being lighter than the same components made of steel, of being insensitive to corrosion and of having superior mechanical properties. These components are produced by melt-injection-moulding and/or thermoforming of a thermoplastic. However, there is a technical difficulty, namely that it is much more difficult to paint them than steel components. One solution consists in covering these components with a coloured film, this film possibly being a monolayer or a multilayer. Usually, this film is placed in the bottom of a mould and then the molten plastic (the substrate) is injected onto it and, after cooling and demoulding, the component coated with the coloured film—this is the technique of overmoulding. The adhesion of the film is provided by contact between the molten plastic and the film, causing that surface of the film facing the injection of the molten plastic to melt and thus to be welded. It is also possible to coextrude the substrate and the coloured film, to coat the substrate on the coloured film or to hot-press the substrate onto the coloured film, and then optionally to thermoform the assembly.
The present invention relates to these films and to the substrates coated using this technique.
PRIOR ART
Patent U.S. Pat. No. 5,514,427 proposes the use of the so-called solvent casting technique for uniformly dispersing pigments, dyes and fillers in a multilayer film. The solvent casting technology consists firstly in producing a liquid thermoplastic polymer composition in a solvent containing the actual polymers, the dispersion of pigments and the additives meeting a given specification. This liquid composition is then uniformly deposited on a supporting strip. The latter is taken into a drying oven in which the solvents are extracted by evaporation and in which the composition is melted in order to form a continuous layer. The continuous film is then wound up. The structure of the film comprises, bearing from the inside (the substrate side; which is made of a polyolefin or acrylonitrile-butadiene-styrene) to the outside, a layer of a chlorinated polyolefin, an acrylic adhesive layer and a pigmented layer based on a fluoropolymer and on alkyl methacrylate.
Patent WO 99/37479 describes a multilayer film obtained by the technique called solvent casting and lamination, which has, respectively from the inside (substrate side) to the outside, an adhesive layer of the pressure-sensitive adhesive type, an opaque pigmented layer of a fluoropolymer in which the fillers have no particular orientation and a transparent layer based on a fluoropolymer.
Patent EP 949,120 proposes a multilayer film consisting, from the inside to the outside, of a polymer support layer (polyolefin, acrylo-nitrile-butadiene-styrene, polyamide, etc.), of a methacrylate base layer, of a colour-pigmented fluorinated layer (with no particular orientation) and of a transparent fluorinated layer, it then being possible for this film to be overmoulded by various substrates, such as polyolefin or polyamide substrates.
Patent U.S. Pat. No. 5,725,712 proposes a thermoformable multilayer film obtained by lamination, consisting, from the inside to the outside, of an adhesive layer, of a pigmented colour layer, in which the fillers have no particular orientation, and of a transparent layer.
Patent U.S. Pat. No. 5,707,697 describes an external decorated and weather-resistant body component. This component consists of a multilayer film, obtained by the technique called solvent casting, followed by lamination, and of a substrate. The structure of the film comprises, from the inside to the outside, a chlorinated polyolefin layer capable of adhering to a polyolefin substrate, a pigmented colour fluoropolymer-based layer in which the fillers do not have any particular orientation and a transparent flouropolymer layer having a shiny appearance.
Patent WO 96/40480 describes a multilayer structure which, from the inside to the outside, has a reinforcing layer (of the ABS type) coated by coextrusion with an adhesion primer (acrylic), then with a coloured layer consisting of a PVDF-based copolymer as a blend with an acrylic and of a transparent surface layer consisting of a blend of homopolymer PVDF with an acrylic.
Patent WO 94/03337 proposes a multilayer consisting, from the inside to the outside, of a substrate, of an adherent layer consisting of a compound compatible with the substrate, of a reinforcing layer, of a coloured layer which contains pigments in an acrylic, urethane or vinyl matrix, and finally of a transparent layer based on PVDF and PMMA having a compositional gradient. The reinforcing layer may consist of PBT, PET, ABS, PVC, PA, a polyester, PC, a polyolefin, an ethylene-alkyl (meth)acrylate copolymer, an acrylic polymer or a blend of at least any two of these polymers.
U.S. Pat. No. 5,658,670 describes a two-layer film obtained by coextrusion and hot-pressing of a layer of PVDF or derivatives and of an amine-modified PA, polyurethane or polyolefin layer.
Patent Application JP 09-193189 A, published on Jul. 29, 1997, describes a film comprising 4 layers which, from the inside to the outside, are a polypropylene layer, a filled (pigmented) polypropylene layer, a layer of an ethylene-glycidyl methacrylate copolymer and a transparent surface layer based on polymethyl methacrylate (PMMA), respectively.
Patents FR 2,740,384 and FR 2,740,385 describe a film possessing three of four layers based on a polyamide and on chemically modified polypropylene, allowing decorated surfaces to be produced.
THE TECHNICAL PROBLEM
In the films of the prior art, the weak point is the adhesion of the fluoropolymer layer to the other layers. Multilayer films useful for the protection and decoration of substrates have now been found, these films having an external layer made of a fluoropolymer or PMMA or mixtures thereof adhering perfectly to the substrate. The film of the invention is also much simpler to manufacture than that of the prior art; in particular it requires no solvent.
BRIEF DESCRIPTION OF THE INVENTION
The present invention relates to a thermoformable multilayer film comprising in succession:
a protective layer (A);
a transparent layer (B) comprising (by weight the total amount being 100%) 0 to 100% of a fluoropolymer (B1) and 100 to 0% of a polymer (B2) essentially consisting of alkyl (meth)acrylate units;
a layer (C) based on a polyamide with amine terminal groups;
a layer (D) consisting of a polyolefin functionalized by an unsaturated carboxylic acid anhydride;
a bonding layer (E) made of a polyolefin.
This film is obtained by coextruding the various layers, the layer (A) possibly being laminated using the standard technique for thermoplastics. This film is then used to cover various substrates, for example by injection-moulding the substrate in the melt onto the multilayer film placed in the bottom of an injection mould, the layer (A) of the film being placed against the wall of the mould.
The present invention also relates to substrates coated with these films.
DETAILED DESCRIPTION OF THE INVENTION
The protective layer (A) is a temporary layer allowing the shiny and transparent layer (B) to be protected during the steps of handling, thermoforming, and injection-moulding the film. This protective layer makes it possible to maintain or promote a given surface finish. Thus, this layer may be smooth or rough, depending on the desired surface finish. This layer avoids the use of a demoulding agent capable of degrading the surface finish of (B). Advantageously, this layer has a thickness of between 10 and 150 &mgr;m and preferably from 50 to 100 &mgr;m. The materials that can be used to produce this layer may be chosen from
Bonnet Anthony
Bussi Philippe
Silagy David
Teixeira Pires Jose
Atofina
Millen White Zelano & Branigan P.C.
Zacharia Ramsey
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