Title of Invention

A STRETCHED MULTI-LAYER MONOFILAMENT AND A PROCESS FOR MANUFACTURING THE SAME

Abstract

A stretched monofilament comprising a continuous stretched and heat-set plastic A consisting of at least one plastic selected from the group consisting of polyethylene terephthalate, polypropylene, polyamide, and polyamide copolymer, a continuous stretched and heat-set plastic B at least partially enclosing, bonded to, and extending a full length of the first portion, and a continuous stretched and heat-set plastic C at least partially enclosing, bonded to, and extending a full length of the plastic B and having a composition different from that of the plastic A and selected from the group consisting of polyethylene, polypropylene, polyoxymethylene, polyphenylene sulfide, polyvinyl chloride, polymethylmethacrylate, polybutylene terephthalate, polyether etherketone and polyethylene naphthalate, the second layer 2 being sandwiched between the first layer 1 and third layer 3.

Full Text

MULTI-LAYER MQNOFILAMENT AND PROCESS FOR MANUFACTURING A MULTI-LAYER MONOFILAMENT The invention relates to a multi-layer monofilament. The invention further relates to a method for manufacturing such a multi-layer monofilament. The principle of manufacturing or spinning two-layer monofilaments or bicomponent filaments from two different thermoplastic plastics is known. In this way, monofilaments receive their corresponding properties, which cannot be achieved in one plastic alone. It is known to produce these monofilaments from two layers either in a side-by-side arrangement or in a core/sheet arrangement. Many bicomponent filaments, particularly those with a core/sheet structure, have the disadvantage that the adhesion between the two layers (core and sheet) is inadequate and they can therefore easily delaminate. Particularly when these monofilaments are stretched, it often happens that the sheet layer peels away from the core like an onionskin. These problems occur in many plastic pairs. In view of this, the technical problem underlying the invention was to suggest a multi-layer monofilament of the type described in the introduction, which does not suffer from the problems explained above and in which the individual layers are adequately bonded with each other. In order to solve this technical problem, the invention proposes a multi-layer monofilament consisting of multiple layers that are extruded or spun simultaneously in a single process step, having a first layer made from plastic A, a second layer, which is bonded directly to the first layer, made from plastic B, and a third layer, which is bonded directly to the second layer, made from plastic C, plastic B being a bonding agent between the two plastics A and C. Multiple layers are said to be simultaneously extruded or spun in particular when the liquefied plastics intended for use in the multiple layers of the monofilament are ejected from the same spinning orifice or spinning device together, thereby creating the multi-layer monofilament. A spinning device of such kind is normally equipped with multiple spinning orifices. - For the purpose of the invention, a bonding agent is a plastic that serves to improve the adhesive bond between two plastics to be bonded. The scope of the invention applies expressly to multiple- layer monofilaments including only three layers. Thus the object of the invention is preferably a three-layer monofilament. - A highly advantageous embodiment, to which particular importance attaches within the scope of the invention, is characterised in that the monofilament has a core/sheet structure, wherein the core of the monofilament is formed by plastic A, wherein this core is at least partly enclosed by the second layer consisting of plastic B, and wherein the second layer consisting of plastic B is at least partly enclosed by the third layer consisting of plastic C. In this core/sheet structure, the core consisting of plastic A is thus equivalent to the first layer consisting of plastic A. For practical reasons, the core has a circular or elliptical cross-section. The scope of the invention expressly includes the fact that the core is fully enclosed by the second layer consisting of plastic B, and that it preferably has a circular cross-section. According to a preferred embodiment, the second layer consisting of plastic B is entirely enclosed by the third layer consisting of plastic C and that it has a circular cross-section for practical purposes. - In all cases, the scope of the invention expressly includes the fact that a multi-layer monofilament according to the invention has a side-by-side structure. According to one particularly preferred embodiment of the invention, plastic B, i.e. the adhesive agent, is an ethylene-vinylacetate copolymer and/or a methylacrylate copolymer. Preferably, one of the two layers to be bonded by means of plastic B, i.e. by means of the bonding agent, i.e. the first layer consisting of plastic A or the third layer consisting of layer C, is made from at least one plastic from the group "polyethylene terephthalate (PET), polyamide (PA) , polyamide copolymer, polypropylene (PP)". The scope of the invention expressly includes the fact that a polyamide 6 and/or polyamide 6.6 and/or polyamide 6.12 is used as the polyamide. According to a preferred embodiment of the invention, the other of the two layers to be bonded by means of plastic B, i.e. by means of the bonding agent, i.e. the first layer consisting of plastic A or the third layer consisting of layer C, is made from at least one plastic from the group "polyethylene (PE), polyoxymethylene (POM), polyphenylene sulphide (PPS), polymethylmethacrylate (PMMA), polybutylene terephthalate (PBT), polyvinyl chloride (PVC), polyether etherketone (PEEK), polyethylene naphthalate (PEN)". Furthermore, the object of the invention is a process for manufacturing a multi-layer monofilament, the monofilaments being produced by means of a spinning device having a plurality of spinning orifices, wherein one liquefied plastic for each layer of the monofilament is directed to the respective spinning orifice and wherein the liquefied plastics for various layers are ejected from the spinning orifice together, thereby forming a single multi-layer monofilament. According to a particularly preferred embodiment of the invention, a multi-layer monofilament having a core/sheet structure is produced, wherein the liquefied plastic of plastic A is directed to each spinning orifice via a feeding channel provided centrally over the spinning orifice to form the core of the monofilament, wherein the liquefied plastic of plastic B (bonding agent) is directed to form an inner sheet via an inner feeding slit encircling the feeding channel in annular manner and wherein the liquefied plastic of plastic C is directed to form an outer sheet via an outer feeding slit encircling the inner, annular feeding slit. The scope of the invention expressly provides for the fact that the inner and/or the outer feeding slits is/are feeding slits that encircle the feeding channel in annular manner. According to a particularly preferred embodiment of the invention, the multi-layer monofilaments are stretched after spinning. Stretching is advantageously done in one to three stages. Stretching may take place in air, or in steam or in water. The multi-layer monofilaments are preferably fixed following the stretching. In this case, fixing means that the multi-layer monofilaments are heated, specifically to a temperature above 20°C, preferably above 25°C. Fixing may also take place in one to three stages and is preferably done in air or in steam or in water. The invention is based on the realization that the layers of the multi-layer monofilaments according to the invention adhere to each other surprisingly strongly. When these multi-layer monofilaments are stretched, the layers do not delaminate. In addition, the multi-layer monofilaments according to the invention may be manufactured relatively simply and inexpensively. The invention will be described in detail with reference to a Ricon Paying drawing illustrating just one embodiment of the invention. The single figure shows a cross-section through a multi-layer monofilament according to the invention. In the embodiment according to the figure, the multi-layer monofilament is formed as a three-layer monofilament specifically having a core/sheet structure. Core 1 here corresponds to the first layer of the multi-layer monofilament made from plastic A. Preferably and in the embodiment, core 1 has a circular cross-section. In the embodiment shown in the figure, this core 1 is surrounded by an inner sheet 2, which corresponds to the second layer consisting of plastic B, i.e. the bonding agent. Inner sheet 2 surrounds core 1 in annular manner. This inner sheet 2 is in turn surrounded by an outer sheet 3, which corresponds to the third layer consisting of plastic C. This outer sheet 3 surrounds inner sheet 2 consisting of plastic B in annular manner. In the embodiment, inner sheet 2 may consist of ethylene vinylacetate copolymer as a bonding agent. We Claim: 1. A stretched monofilament comprising a continuous stretched and heat-set plastic A consisting of at least one plastic selected from the group consisting of polyethylene terephthalate, polypropylene, polyamide, and polyamide copolymer, a continuous stretched and heat-set plastic B at least partially enclosing, bonded to, and extending a full length of the first portion, and a continuous stretched and heat-set plastic C at least partially enclosing, bonded to, and extending a full length of the plastic B and having a composition different from that of the plastic A and selected from the group consisting of polyethylene, polypropylene, polyoxymethylene, polyphenylene sulfide, polyvinyl chloride, polymethylmethacrylate, polybutylene terephthalate, polyether etherketone and polyethylene naphthalate, the second layer being sandwiched between the first layer and third layer. 2. The multi-layer monofilament as claimed in claim 1, wherein the monofilament consists of three layers. 3. The multi-layer monofilament as claimed in either of claims 1 or 2, wherein the monofilament has a core/sheet structure. 4. The multi-layer monofilament as claimed in either of claims 1 or 2, wherein the monofilament has a side-by-side structure. 5. The multi-layer monofilament as claimed in any of claims 1 to 4, wherein the plastic B (bonding agent) is an ethylene-vinylacetate copolymer and/or a methylacrylate copolymer. 6. A process for manufacturing a multi-layer monofilament as claimed in any of claims 1 to 5, wherein the monofilaments are produced by means of a spinning device having a plurality of spinning orifices, wherein one liquefied plastic for each layer of the monofilament is directed to the respective spinning orifice and wherein the liquefied plastics for the various layers are ejected from the spinning orifice together, thereby forming a single multi- layer monofilament and wherein the multi-layer monofilaments are stretched and fixed after stretching. 7. The process as claimed in claim 6, wherein a core/sheet structure is formed, wherein the liquefied plastic of plastic A is directed to each spinning orifice via a feeding channel provided centrally over the spinning orifice to form the core, wherein the liquefied plastic of plastic B (bonding agent) is directed to form an inner sheet via an inner feeding slit at least partly encircling the feeding channel, and wherein the liquefied plastic of plastic C is directed to form an outer sheet via an outer feeding slit at least party encircling the inner feeding split. Dated this 28th day of January 2004. A stretched monofilament comprising a continuous stretched and heat-set plastic A consisting of at least one plastic selected from the group consisting of polyethylene terephthalate, polypropylene, polyamide, and polyamide copolymer, a continuous stretched and heat-set plastic B at least partially enclosing, bonded to, and extending a full length of the first portion, and a continuous stretched and heat-set plastic C at least partially enclosing, bonded to, and extending a full length of the plastic B and having a composition different from that of the plastic A and selected from the group consisting of polyethylene, polypropylene, polyoxymethylene, polyphenylene sulfide, polyvinyl chloride, polymethylmethacrylate, polybutylene terephthalate, polyether etherketone and polyethylene naphthalate, the second layer 2 being sandwiched between the first layer 1 and third layer 3.

Documents:

40-kol-2004-granted-abstract.pdf

40-kol-2004-granted-claims.pdf

40-kol-2004-granted-correspondence.pdf

40-kol-2004-granted-description (complete).pdf

40-kol-2004-granted-drawings.pdf

40-kol-2004-granted-examination report.pdf

40-kol-2004-granted-form 1.pdf

40-kol-2004-granted-form 18.pdf

40-kol-2004-granted-form 2.pdf

40-kol-2004-granted-form 3.pdf

40-kol-2004-granted-form 5.pdf

40-kol-2004-granted-pa.pdf

40-kol-2004-granted-reply to examination report.pdf

40-kol-2004-granted-specification.pdf

40-kol-2004-granted-translated copy of priority document.pdf