Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1993-06-17
1994-11-01
Cannon, James C.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
57243, 57250, 57258, 57905, 139420A, 156181, 156224, 264258, 264324, 428 361, 428 363, 428 3691, 428 3692, 428110, 428113, 428114, 428229, 428240, 428259, 428373, 428394, B29C 5100, B32B 3120, C09K 1938, D02G 304
Patent
active
053605039
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a reinforced thermoplastic composite product to be used in the manufacture of entirely thermoplastic, reinforced composite materials having high mechanical and physicochemical performance characteristics. The composite materials to which the invention applies are fibrous reinforcement materials.
Known composite materials are constituted by mineral or organic reinforcing fibres ensuring the strength and rigidity of the parts and an organic or inorganic matrix ensuring the connection between the reinforcing fibres, as well as the transfer of forces between said fibres. The fibres are generally of glass, silica, carbon, silicon carbide, alumina and aramide. The matrix is generally of metal, glass, ceramic or thermosetting resin.
These composite materials can be used in numerous industrial fields and in particular in the space, aeronautical, avionics, car, nautical and competition sports fields, as well as in general terms for producing light-weight mechanical parts having high mechanical strength characteristics.
The combination of fibres and matrixes of different physicochemical natures leads to interface problems between the fibres and the matrix such as wettability, adhesion, oxidation, the creation of another substance (e.g. an oxide in the case of non-oxide ceramic fibres), etc. These phenomena are generally dealt with by adding at least one third organic or inorganic product deposited on the fibres and/or in the matrix. When this third product is deposited on the fibres, it is known as a sizing agent.
The use of this third material somewhat complicates the manufacture of composite materials, thus increasing their manufacturing time and also their costs.
In order to reduce production costs, improved mechanical and physicochemical performance characteristics and the resistance to damaging of composite materials with a fibrous reinforcement, it is known to use a thermoplastic matrix in place of thermosetting matrix or an inorganic matrix. However, the thermoplastics used at present for the matrix have high use temperatures (exceeding 400.degree. C.) which, apart from a high energy consumption, leads to the use of difficult tools for controlling the pressure in the mould, which is also prejudicial to the production costs and production efficiency of these composites.
Reference is made to EP-A-340 655 as a document relating to entirely thermoplastic products using matrixes with a high use temperature.
EP-A-303 173 describes moulded articles in the form of sheets constituted by aramide fibres or aromatic polyester fibres or films. Unlike aramide, the latter has an anisotropy in the melted state. In addition, aramide is not a thermoplastic polymer (cf. in this connection EP-A-329 939). These polymers of different natures consequently have the aforementioned interface problems.
The present invention relates to a solid, thermoplastic composite semi-finished product to be used in the manufacture of composite materials having reinforcing fibres making it possible to obviate the disadvantages referred to hereinbefore. In particular, it avoids the use of an additional interphase material between the fibres and the matrix of a composite material, while eliminating the interface problems between the latter.
For this purpose, the invention proposes producing a novel, entirely thermoplastic composite material, whose reinforcing fibres and matrix are of the same chemical nature or natures which are very similar to one another.
Moreover, the invention makes it possible to reduce production costs and simplify the production of the composite materials by the use of special thermoplastic polymers for forming the matrix of composite materials. These polymers are liquid crystal polymers known under the abbreviation LCP.
Thermotropic liquid crystal polymers (LCP) are crystalline polymers having four stable states and three phase change temperatures: solid-liquid crystal, liquid crystal-isotropic liquid and isotropic liquid-gas.
The liquid crystal state consists of an arrangement of molecules and
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Aerospatiale
Cannon James C.
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