Method and Device for Producing a Composite Yarn
The invention concerns a method for making continuous coextruded intermingled glass filaments and continuous thermoplastic organic filaments that enable non-spinnable compounds to be incorporated at the thermoplastic filaments. The invention is characterized in that the thermoplastic filaments are obtained by coextrusion of a thermoplastic material acting as core and a thermoplastic material containing at least one non-spinnable compound. The invention also concerns a device for implementing the method. The resulting composite yarn is provided with specific core properties provided by the non-spinnable compounds.
1 . A process for manufacturing a composite strand formed by combining continuous glass filaments emanating from a bushing with continuous thermoplastic filaments emanating from at least one spinning head, these filaments being drawn and commingled in the form of a web into a bundle or web of glass filaments, characterized in that the thermoplastic filaments are obtained by coextruding an organic thermoplastic in a manor amount (called the main material) with an organic thermoplastic present in a minor amount and containing at least one nonspinable compound (called the secondary material).
2 . The process as claimed in claim 1 , characterized in that the coextrusion is carried out in such a way that the secondary material is distributed on the surface of the main material, which serves as a core.
3 . The process as claimed in claim 1 , characterized in that the coextrusion is carried out in such a way that the secondary material is included within the main material.
4 . The process as claimed in one of claims 1 to 3 , characterized in that the main material and the secondary organic thermoplastic are chosen from polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon-6, nylon-6,6 and nylon-12, polyphenylene sulfide and polyurethanes.
5 . The process as claimed in one of claims 1 to 4 , characterized in that the stream of the main material represents at least 50%, preferably 70 to 95%, by weight of all of the materials entering the spinning head.
6 . The process as claimed in one of claims 1 to 5 , characterized in that the weight content of nonspinable compound(s) in the secondary material is less than 80% and preferably varies from 1 to 50% and better still varies from 10 to 30%.
7 . A device for manufacturing a composite strand formed by combining continuous glass filaments with continuous organic thermoplastic filaments, which device comprises, on the one hand, at least one bushing supplied with molten glass, the lower face of which has a very large number of holes and is associated with a coating device, and, on the other hand, at least one spinning head supplied under pressure with molten organic thermoplastic, which includes a very large number of holes, and means for drawing and spraying the thermoplastic filaments for the purpose of mingling them with glass filaments and means common to the bushing and to the spinning head for assembling and optionally winding the composite strand, characterized in that the spinning head is suitable for coextruding a main material with a secondary material containing at least one nonspinable compound.
8 . The device as claimed in claim 7 , characterized in that the spinning head has an internal geometry allowing the main material and the secondary material to be delivered separately right to the spinneret plate.
9 . A composite strand obtained by the process as claimed in one of claims 1 to 6 , the said strand comprising thermoplastic filaments containing at least one nonspinable compound.
10 . A product, especially in the form of a mat, woven, knit or braid, containing at least one strand as claimed in claim 9 .
11 . A composite having a thermoplastic matrix reinforced by glass strands obtained from the strand as claimed in claim 9 .