Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1998-09-15
2000-08-15
Yao, Sam Chuan
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
156324, 1563099, 2641761, A41D 2700, B32B 3120
Patent
active
061030457
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention concerns a method of producing sheets or plates of thermoformable plastics material for use as a thermoadhesive reinforcing material or for the preparation of orthopaedic reinforcing pieces.
BACKGROUND OF THE INVENTION
The footwear and leather industry among others requires reinforcing parts which must have a range of characteristics, the main characteristics being as follows: 80.degree. C.-90.degree. C., and regain their rigidity fairly rapidly at ambient temperature; 80.degree. C.-90.degree. C., at a pressure of a few bars and in the space of a few seconds on a variety of backings such as natural or synthetic leathers, thermoplastic materials, natural or synthetic textiles, elastomers, etc.; and
French patent FR-A-2 392 810 describes a product of this type constituted by a synthetic material (binder) reinforced with an inert filler material.
European patent EP-A-0 183 912 describes a material of the same type, in which the filler material is entirely or at least superficially constituted by plastics material.
In both cases the starting substances, the binder and the filler material, are constituted by powders with comparable grain sizes preferably of 50 .mu.m to 500 .mu.m, in particular 100 .mu.m to 400 .mu.m. Powders with such grain sizes can cause cost problems in production and handling as well as suffering from the usual problems of powders, namely static electricity and irregularity of the physico-chemical properties of the products obtained.
FR-A-2 559 503 describes stiffening materials for leather, constituted by at least one layer of synthetic material obtained by sintering a mixture of two polymer components with different melting points. The product obtained is not thermoadhesive.
SUMMARY OF THE INVENTION
The invention overcomes the problem by providing sheets and/or plates which are thermoformable from a temperature of 80.degree. C.-90.degree. C. and thermoadhesive from the same temperature, for use as a thermoadhesive reinforcing material, obtained by a method which is characterized in that:
30% to 70% by weight of granules of polymer(s) with a low melting point (of the order of 50.degree. C. to 90.degree. C.) which are thermoformable from a temperature of 80.degree. C.-90.degree. C. are mixed with 70% to 30% by weight of polymer(s) with a higher melting or softening point, in granules or as a powder with a grain size of more than about 500 .mu.m, preferably in the range 500 .mu.m to 1000 .mu.m, the two types of polymer being thermoplastic and completely or partially compatible, and optionally with the usual additives; 100.degree. C. to 140.degree. C. to produce a mixture with a paste-like consistency which is insufficient for the formation of a homogeneous mixture of molten polymers; extruded product, the product is rolled or calendered at high pressure at a temperature which is of the order of 100.degree. C. to reduce its thickness, with cooling to a temperature of less than 30.degree. C. before rolling or calendering is completed.
The low melting point polymer can be a polyester, polyurethane, ethylene/acetate copolymer or ethylene/acrylic monomer copolymer with a melting point of 50.degree. C. to 90.degree. C. These polymers are in the form of grains of about 2 mm to 3 mm, such as those which are commercially available. Other polymers can also be used, provided that they have adhesive properties at low temperatures. and at low pressures.
Examples of higher melting or softening point polymers are polyvinyl chlorides, polycarbonates, polyethylenes, ABS (acrylonitrile/butadiene/styrene) or any other polymer which is completely or partially compatible with the low melting point polymers cited above, in the form of grains such as those which are commercially available (2 mm to 3 mm granules), or in the form of powders which preferably have a grain size of 500 .mu.m to 1000 .mu.m. Such powders can be obtained during plastics material recovery treatment.
The use of such grain sizes results in an effective mixture of the two types of polymer which is ea
Cirier Jean-Pierre
Poisson Hubert
Stampfer Francoise
Lambiotte S.A.
Yao Sam Chuan
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