Thermoformable lap having reinforcement fibres

Abstract

A thermoformable lap (1) includes a first web (3) and a second web (4) made of linking fibres (3a, 4a) made of a first thermoreactivatable material having a first reactivation temperature. An intermediate layer (2) is arranged between the first web (3) and the second web (4), and includes reinforcement fibres (2a) and granules (2b) of a second thermoreactivatable material having a second reactivation temperature that is higher than the first reactivation temperature. Certain sections (3b, 4b) of linking fibres of the first and second webs (3, 4) penetrate into the intermediate layer (2) and partially adhere to one another and to the reinforcement fibres (2a) of the intermediate layer (2), ensuring the cohesion of the assembly. Such a lap can be manufactured at a lower cost and at high speed, and can be used for the production of parts by heat moulding.

Description

TECHNICAL FIELD OF THE INVENTION[0001]The present invention relates to the thermoformable laps based on reinforcement fibers and thermofusible or thermoreactivatable material, that can be used to produce parts made of composite material by hot pressing.[0002]The document U.S. Pat. No. 3,863,758 A discloses a lap based on glass fibers and thermoplastic polymer powder, that can be hot molded. The glass fibers and the thermoplastic polymer powder are mixed and encapsulated between two outer layers whose edges are sealed and which prevent the glass fibers and the powder from escaping. The outer layers are films of thermoplastic polymer compatible with the thermoplastic polymer powder. However, a first drawback is that the very production of the thermoplastic material in powder form is relatively costly. A second drawback is that such known laps with fine powder are sensitive to ageing, and require particular and restrictive storage conditions (short duration, low temperature, absence of...

AI Technical Summary

Benefits of technology

The invention is about a way to make a thermoformable lap using a cheaper material called granules. By using two different types of thermoreactivatable material, the cost of production is significantly reduced, while the thermoformable lap becomes less sensitive to ageing. The first material is in granule form, making it easy to handle and form into different shapes. The second material, in the form of reinforcement fibers, helps maintain the strength of the thermoformable lap. The use of linking fibers prevents the granules from escaping and ensures the cohesion of the assembly. The invention also allows for the use of non-woven reinforcement fibers, which simplifies production. The invention thus offers a cheap and efficient way to produce thermoformable laps with improved properties.

Problems solved by technology

However, a first drawback is that the very production of the thermoplastic material in powder form is relatively costly.

A second drawback is that such known laps with fine powder are sensitive to ageing, and require particular and restrictive storage conditions (short duration, low temperature, absence of ultraviolet rays, etc.).

A third drawback is that the lap can be cut only along preformed link lines along which the outer layers are sealed to one another.

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