Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
1999-06-16
2001-11-20
Morris, Terrel (Department: 1771)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S364000, C428S365000
Reexamination Certificate
active
06319606
ABSTRACT:
The invention concerns a monofilament for use in engineering textiles, in particular in papermaking fabrics, made up of a plastic material having a principal constituent that is polytrimethylene terephthalate (PTMT) and at least one additional constituent.
For technical textiles, monofilaments are used in many cases as yarns from which woven or knitted textiles, yarn plies, etc. are manufactured. Either the technical textile comprises such woven or knitted textiles or yarn plies, or the latter form a base for coatings, needle-felted fiber batts, or the like. Particular technical textiles are endless belts—with or without a seam—that travels around in machines. These include papermaking fabrics, which are used to form and transport the paper web through the individual parts if of the papermaking machine, i.e. the forming area and the pressing and drying sections. The papermaking machine cloths are configured differently for the individual parts of the papermaking machine.
A variety of plastic materials have been proposed in the past. Polyester or nylon types, in the latter case predominantly nylon-6 types, have been used for some time in papermaking fabrics (cf. DE-A-44 10 399). More recently it has also been proposed to use nylon-11 or nylon-12 types (cf. JP Published Application 60-52616) both for the base fabric and for the fibers of the needle-felted fiber layers (cf. EP-A-0 070 708, EP-A-0 372 769). It has also been previously proposed to manufacture monofilaments from a core made up, for example, of nylon-6/6 or polyethylene terephthalate, and a sheath of nylon-11 or nylon-12 (cf. EP-A-070 708).
To improve resistance to the chlorine-containing substances that occur in papermaking machines, papermaking fabrics have been designed in which the fibers of the base fabric are made of polybutylene terephthalate, and the needle-felted fiber batt is made of polyethylene terephthalate. Since the mechanical properties of the latter material are poorer than those of nylon, the use of polytrimethylene terephthalate (PTMT), also called polypropylene terephthalate, has been proposed (cf. U.S. Pat. No. 5,137,601), both for the monofilaments of the base fabric and for the fibers of an optional fiber batt covering. This material is said to have the same chemical resistance as polybutylene terephthalate and polyethylene terephthalate, but additionally to have mechanical properties similar to nylon-6, especially with regard to elasticity and abrasion resistance. In terms of temperature resistance, this material is said to be better than nylon-6.
An effort has also been made to combine the good properties of polyester, in particular of polyethylene terephthalate, with considerably improved abrasion behavior (cf. DE-A-44 10 399). It is has been proposed for this purpose to mix a thermoplastic polyurethane into the polyester.
A further development based on polytrimethylene terephthalate is evident from EP-A0 844 320. The latter discloses a monofilament that contains, only in part although also as the principal constituent, polytimethylene terephthalate that is mixed with polyurethane, in particular elastomeric polyurethane, in order to enhance abrasion resistance. It has been found, however, that considerable problems arise in the processing of monofilaments made of PTMT material to produce woven or knitted textiles: inhomogeneity and warping occur. It has been determined that the reason for this is the high elasticity of the PTMT monofilaments, although this elasticity behavior is described in U.S. Pat. No. 5,137,601 as being favorable for manufacturability. The elasticity behavior is also not changed by the admixture of polyurethane proposed in EP-A-0 844 320.
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Publication AN 96-283978.
Liniak Berenato Longacre & White LLP
Morris Terrel
Pratt Christopher C.
Thomas Josef Heimbach Gesellschaft mit beschrankter Haftung & Co
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