Method for producing a flat semi-finished product from a fiber composite material and flat semi-finished product

Abstract

A method produces a flat semi-finished product from a fiber composite material that contains individual carbon fibers, carbon fiber bundles, or a mixture thereof in a defined anisotropic fiber orientation and a thermoplastic matrix material. The anisotropy of the carbon fibers is created in a carding process using the high orientability of admixed non-carbon textile fibers, at least some of the non-carbon textile fibers being thermoplastic, and the carbon fibers having been isolated from waste or used parts. The flat fibrous web which is produced by a carding process and which has a specific orientation of the carbon fibers in the longitudinal direction is compressed into a sheet material under the effect of heat. This enables the use of carbon fibers, for example from production waste, as reinforcing fibers, whereby a less expensive raw material is provided and the carbon fibers are contained in the waste materials are recycled.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is a continuation, under 35 U.S.C. §120, of copending international application No. PCT / EP2011 / 000486, filed Feb. 3, 2011, which designated the United States; this application also claims the priority, under 35 U.S.C. §119, of German patent application No. DE 10 2010 008 370.4, filed Feb. 17, 2010; the prior applications are herewith incorporated by reference in their entirety.BACKGROUND OF THE INVENTIONField of the Invention[0002]The present invention relates to a method for producing a flat semifinished product from a fiber composite material containing fibers and at least one thermoplastic matrix material, wherein fibers are isolated from wastes or used parts containing fibers, then the fibers are blended with thermoplastic fibers and laid out in a sheet in a carding operation, thus producing a fiber web, which is pressed under the influence of heat to form a sheet material in at least one subsequent step.[0003]Carbon f...

AI Technical Summary

Benefits of technology

The present invention provides a method for producing a flat semi-finished product of fiber-reinforced composite material that can be used for high mechanical loads. The method allows for the use of carbon fibers that are available inexpensively and recycled from various sources such as textile production waste and reinforcing fibers. The method also ensures that the carbon fibers are uniformly mixed with a thermoplastic component and processed to prepregs with a uniform weight per unit of area. The resulting flat semi-finished product has a suitable arrangement of reinforcing fibers and is advantageous for the production of structural parts. The amount of thermoplastic component determines the achievable compactness of the sheet material. The method allows for the use of a minimum binder content of 15% to 25% and a sandwich construction with a PA6 needled nonwoven cover layer and RCF in the core area. The resulting sheets are flexible, stable and have positive effects on the stability of the degree of thermal solidification.

Problems solved by technology

Carbon fibers are difficult to process by traditional carding techniques and in particular are difficult to align in a certain preferential direction in a card web because they are smooth and do not have any crimp.

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