Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1993-10-01
1995-11-28
Schofer, Joseph L.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525422, 525419, 525426, 525436, 526262, C08G 7314, C08L 7908
Patent
active
054709202
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to solutions consisting of at least one reactive thermoplastic poly(imide-amide) oligomer, an appropriate coreactant and at least one organic solvent, which can be used especially for the production of preimpregnated intermediate articles by employing the filament winding technique or that for the impregnation of various fibrous materials. It also relates to the active principle of these solutions, consisting of the mixture of at least one reactive thermoplastic poly(imide-amide) oligomer with a coreactant, which can be used for the preparation of the abovementioned solutions. It also relates to the preimpregnated intermediate articles obtained from these solutions.
Preimpregnated (or composite) intermediate articles are used in a known manner for the production of components of various shapes and for various purposes in many industries such as, for example, in aeronautics. These components, which may be components of revolution, are obtained by laying a number of layers of prepregs on a mold or a support. Curing of the impregnating resin is then carried out under the usual technological conditions pertaining to composite materials and in particular at temperatures of between 100.degree. and 300.degree. C.
For impregnation by a solvent route, use has hitherto essentially been made of solutions comprising (as active principle acting as impregnating resin) of a heat-curable polyimide oligomer obtained by reacting an N,N'-bisimide of an unsaturated dicarboxylic acid with an appropriate coreactant. With such impregnating resins, after the solvent has been removed, composites are obtained which give it a very good heat behavior (they withstand, without degrading, temperatures of 200.degree. to 300.degree. C. for a relatively long period, of the order of 10,000 to 100 hours), but this good heat stability is counterbalanced by a relatively brittle nature of the material; to give an idea, it can be pointed out that the value of the energy of propagation of a GlC crack (measured on a unidirectional composite based on carbon fibers, containing 40 g of resin per 60 g of fibers) is then of the order of 100 to 200 J/m.sup.2, which is an inadequate value.
Patent Application EP-A-182589 describes compositions for impregnation including a polyamide-imide polymer resin containing an acid amide functionality in sufficient quantity to make it soluble in an organic solvent and then to be hydrolysed in the presence of water.
Finally, Patent Application EP-A-376892 describes compositions including polyamide-imide polymer resins which can be combined, inter alia with certain resins such an epoxy resin or a bismaleimide.
Continuing its work in this field of the art, the Applicant Company has attempted to develop an improved impregnating solution, that is to say an impregnating solution which not only results in good heat stability but in addition offers access to a composite which has a better impact strength; in this context it is desirable that the value of the GlC toughness referred to above should be higher than 400 J/m.sup.2. Furthermore, the Applicant Company has attempted to develop an impregnating solution in which the active principle forming the impregnating resin which remains on the substrate after the removal of the solvent has a rheology which is perfectly adapted to the processing requirements: in particular, it is desirable that the impregnating resin should, on the one hand, have a marked adhesive nature at ambient temperature (an adhesive resin is intended to define a resin which, when deposited on the substrate and being at ambient temperature, enables this substrate to be positioned merely by pressure and to remain in contact in any position) and, on the other hand, at temperatures between 100.degree. and 300.degree. C. exhibits a flow ratio of between 1 and 20% by weight (weight of resin which has flowed in relation to the weight of the combined resin+substrate).
There have now been found, this being the first subject of the present invention, new impregnating solutions which hav
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Camberlin Yves
Dien Rene
Michaud Philippe
Ciba-Geigy Corporation
Schofer Joseph L.
Teoli, Jr. William A.
Zemel I.
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