Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1989-09-13
1992-08-11
Ryan, Patrick J.
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
156285, 156286, 428224, 428288, 428902, 428241, 428245, 428294, 428408, C09J 502, D03D 300
Patent
active
051375940
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to novel moldings formed from prepregs of unidirectionally arranged carbon filaments and to a method for forming said moldings.
BACKGROUND ART
Carbon fiber reinforced resin moldings produced by impregnating oriented carbon fibers with thermosetting resins, arranging filaments of these fibers unidirectionally to form prepregs, followed by multilayer lamination of these prepregs and molding and curing of resulting laminates are used extensively as industrial materials such as plate springs and honeycomb constructing materials and as sporting or leisure goods such as fishing rods and golf shafts. Recently, those moldings have also been used as members of aircraft, automobiles, ships, and the like.
Performance characteristics of carbon fibers used have also been improved remarkably in recent years; of polyacrylonitrile-based carbon fibers, there have been developed and marketed a high strength, high elongation type having tensile strengths exceeding 600 Kg/mm.sup.2 and a high strength, high elastic modulus type having tensile strengths of at least 300 Kg/mm.sup.2 and tensile elastic moduli of 46-50 ton/mm.sup.2. Performance characteristics required for moldings reinforced with those carbon fibers have been sophisticated more and more against the background of improved performance characteristics of raw material carbon fibers.
The first step of improving the performance of carbon fiber reinforced resin moldings was the enhancement of the adhesive strength between the carbon fiber and the matrix resin. About this matter, extensive researches and developments were made energetically for the past some dozen years and the adhesive strength is settled now on a considerably high level owing to the technique of electrolytic oxidation, the technique of gas-phase oxidation, and some other techniques. Seeing the last several years, however, no marked advance is observed in this art and there is no prospect that properties such as the interlayer shear strength will be improved to large extents in the near future.
While there are already published some reports (Japanese Patent Application Kokai No. Sho. 57-49612, etc.) that a modification of matrix resin contributes to the improvement of its carbon fiber reinforced moldings in performance, not much improvement of the moldings themselves in performance can be expected from the modification of resin when the modified resin has a curing temperature of the same degree. But, matrix resins having higher curing temperatures, higher cross-linking density, and higher stiffness exhibit generally higher interlayer shear strength and higher flexural strength, according to the present inventors' empirical knowledge.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graph showing the relation between the flexural strength of molded plate and the tensile strength of carbon fiber strand.
FIG. 2 is a schematic illustration of the apparatus used in the present invention for producing prepregs.
FIG. 3 is a schematic illustration of an instrument used for the four-point bending test of pipes.
FIG. 4 is a schematic illustration of an instrument for measuring releasing characteristics of release paper sheets. In this drawing, 1 and 6: chucks of a tensile tester, 2: an adhesive tape (adhering surface), 3: a double sided adhesive tape for fixing a test specimen, 4: a supporting metal plate, and 5: a release paper sheet (control surface) to be tested.
DISCLOSURE OF INVENTION
According to the prior art, the combination of carbon fibers with modified matrix resins having curing temperatures of the same degree, in any case, does not effect the performance improvement of carbon fiber reinforced composite moldings in spite of the recent markedly improved performance of carbon fibers. That is the present situation of the art. A particular problem in the art is that the enhanced tensile strength of carbon fibers does not contribute to the improvement of moldings reinforced with these carbon fibers in flexural strength or compression strength, in other w
REFERENCES:
patent: 4173670 (1979-11-01), Van Auken
patent: 4568733 (1986-02-01), Parker et al.
patent: 4714648 (1987-12-01), Nagata
patent: 4816106 (1989-03-01), Tuttis et al.
Asada Shiro
Itani Fujio
Takiguchi Ikuo
Mitsubishi Rayon Co. Ltd.
Ryan Patrick J.
Weisberger Richard C.
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