Evonik Degussa Gmbh

Uwe Stapperfenne

Sandra Reemers

Markus Hallack

Christina Cron

Marina-Elena Schmidt

Tobias Gutmann

Giselher Franzmann

Doris Faber

Leif Ickert

Christina Diehl

The invention relates to a process for producing a prepreg based on polyurethane, which is notable for high storage stability at room temperature, a two-stage reaction mechanism, and adjustable adhesion on metal surfaces. It is based on the problem of making the surface tack of the prepregs controllable during processing. The solution is to assemble the PU mixture from which the matrix originates at a later stage such that the glass transition temperature of the thermoplastic polymer is above 30&#xb0; C. For this purpose, the invention proposes two basically independent but certainly synergistic measures, namely:

Polyurethane prepregs with controllable tack

The invention relates to a hybrid component part comprising a local stiffening made of a two-stage-crosslinked polyurethane-based fiber composite material, more particularly to the production of such a hybrid component part. Said invention has for its object to specify a technology which makes it possible in cost-effective fashion to effect local stiffening of metal parts with a fiber composite material in order thus to obtain a hybrid component part. It is a fundamental concept of the process according to the present invention to use a particular polyurethane formulation which in a first crosslinking reaction can be converted into a thermoplastic polymer and later in a second crosslinking reaction is fully crosslinked to afford a thermoset matrix material. The thermoplastic polymer is characterized by a good adhesion to metal surfaces. The metal can be subjected to further forming with the attached thermoplastic material. The polyurethane is subsequently thermosettingly cured and achieves its final stiffness.

Hybrid component part comprising a local stiffening composed of a two-stage-crosslinked polyurethane-based fibre composite material

A method of producing a fiber composite component part has the following steps: a) providing two or more metal sheets each comprising an aluminum material; b) providing at least one textile fabric; c) providing an anhydrous mixture having one or more than one hardener having a uretdione having an NCO functionality of not less than two, one or more than one binder having hydroxyl groups to an OH functionality of three to six, and one or more than one cobinder having oxirane groups; d) coating the textile fabric with the anhydrous mixture, to obtain a mixture-coated fabric; e) applying energy to the mixture-coated fabric for the purpose of performing a first crosslinking reaction to react hardener, binder and cobinder to form a thermoplastic polymer adhering to the textile fabric; f) hot pressing the metal sheets and the textile fabric together with the thermoplastic polymer adhering thereto into a sandwich such that the thermoplastic polymer joins the metal sheets together while enclosing the textile fabric; g) forming the sandwich into a shaped article; and h) heat treating the shaped article to obtain the fiber composite component part, wherein the thermoplastic polymer undergoes a second crosslinking reaction to convert into a thermoset polymer.

Production of fibre composite component part based on aluminium and polyurethane

A method of producing a fiber composite component part, contains the following steps: a) providing two or more steel sheets; b) providing at least one textile fabric; c) providing an anhydrous mixture having one or more than one hardener containing a uretdione having an NCO functionality of not less than two, one or more than one binder having hydroxyl groups to an OH functionality of three to six, and one or more than one cobinder having oxirane groups; d) coating the textile fabric with the mixture; e) applying energy to the mixture-coated fabric for the purpose of performing a first crosslinking reaction to react hardener, binder and cobinder to form a thermoplastic polymer adhering to the textile fabric; f) hot pressing the steel sheets and the textile fabric together with the thermoplastic polymer adhering thereto into a sandwich such that the thermoplastic polymer joins the steel sheets together while enclosing the textile fabric; g) forming the sandwich into a shaped article; h) heat treating the shaped article to obtain the fiber composite component part, wherein the thermoplastic polymer undergoes a second crosslinking reaction to convert into a thermoset polymer.

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Wülfrath, Germany

Uwe Stapperfenne