Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2000-07-20
2002-11-12
Edwards, Newton (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S397000, C428S394000, C428S422000
Reexamination Certificate
active
06479143
ABSTRACT:
TECHNICAL FIELD
The present invention relates to fibers or mixed fibers of heat-meltable fluorine-containing resin having a branched structure and a non-woven fabric made by using said fibers.
BACKGROUND ART
For making a non-melt-processable fluorine-containing resin represented by polytetrafluoroethylene (PTFE) and a heat-meltable fluorine-containing resin such as tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer (PFA) or ethylene/tetrafluoroethylene copolymer (ETFE) into a fiber, a melt-spinning method, an emulsion-spinning method or a method of cutting a film into a fine and long size has been employed. Fluorine-containing resin fibers obtained through those methods are linear fibers having no branch.
However since a surface of the fluorine-containing resin has good lubricity, sufficient intermingling between the fibers cannot be obtained and therefore the fluorine-containing resin is not suitable, for example, as a material for non-woven fabrics.
The present inventors have developed fibers having a branch, loop and crimp and being excellent in intermingling property by a method of tearing and opening a uniaxially stretched PTFE film by a mechanical force and a method of splitting, and have filed patent applications for various forms and uses (WO94/23098, WO96/00807, WO96/10662, WO96/10668, WO97/26135)
However with respect to melt-processable heat-meltable fluorine-containing resin, under the same method and conditions as in PTFE, opening by dividing of a film does not occur in a film feeding direction, only breaking of a film in a stretching direction occurs and the film cannot be split but stretched and torn, though the reason for that is not known. Thus useful fibers having a branched structure could not be obtained.
An object of the present invention is to provide novel heat-meltable fluorine-containing resin fibers having a branched structure and various materials made by using the same.
DISCLOSURE OF INVENTION
Namely the present invention relates to heat-meltable fluorine-containing resin fibers having a branched structure or cotton-like materials, particularly staple fibers, for example, ETFE staple fibers or cotton-like materials.
Also the present invention relates to mixed fibers or cotton-like materials comprising heat-meltable fluorine-containing resin fibers having a branched structure and one or two or more of other fibers, particularly mixed fibers or cotton-like materials, in which other fibers are electrically conductive fibers or fluorine-containing resin fibers containing a photo-degrading catalyst.
Further the present invention relates to a non-woven fabric made by using those fibers or mixed fibers.
BEST MODE FOR CARRYING OUT THE INVENTION
The heat-meltable fluorine-containing resins to which the present invention is applied are, for example, tetrafluoroethyleneperfluoro(alkyl vinyl ether) copolymer (PFA); ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), polyvinylidene fluoride (PVdF), polyvinyl fluoride (PVF), tetrafluoroethylene-hexafluoropropylene-perfluoro(alkyl vinyl ether) copolymer, and the like. Among them, ETFE is preferred from the viewpoint of heat resistance and chemical resistance.
The fibers can be in the form of staple fiber, split yarn or the like. The fibers in those forms having a branched structure are the fibers of the present invention. Among them, fibers in the form of staple fiber are preferred from the viewpoint of intermingling property and mix spinning property.
As a method for producing heat-meltable fluorine-containing resin fibers having a branched structure, there are:
(1) a method for stretching a heat-meltable fluorine-containing resin film, preferably stretching by five times or more and then tearing and opening by a mechanical force, for example with a combing roll or needle blade roll,
(2) a method for stretching a heat-meltable fluorine-containing resin film, preferably stretching by five times or more and then splitting the film with a needle blade roll or the like to form a network structure and cutting the linkage in the network structure, and the like method.
As the method (1) of tearing and opening, the method disclosed in, for example, WO94/23098 can be employed. For example, fibers having a branch can be obtained by passing a uniaxially stretched film between a pair of needle blade rolls through pinch rolls, in which at the time of tearing with needle blades, a feeding speed at the pinch rolls and the number of needles embedded on the needle blade rolls and arrangement of the needles are selected optionally. In order to uniaxially stretch a heat-meltable fluorine-containing resin film such as ETFE until the film can be applied to the above-mentioned tearing and opening, the film is uniaxially stretched gradually, namely the stretching step is divided into multi stages. Thus enough stretching can be achieved.
The fibers obtained in the method (1) are staple fibers and usually have the following characteristics.
Branch: At least one branch, preferably two or more branches are present on one fiber (filament). The branch may be in the form of loop.
Crimping: Number of so-called crimps which enhance intermingling property. The number of crimps is preferably from 1 to 15/20 mm fiber length.
Fiber length: 1 to 250 mm
Fineness: 2 to 200 deniers
As the splitting method in the method (2), a method explained, for example, in WO96/00807 in detail can be adopted.
For example, the pinch rolls and needle blade rolls used in the method (1) are synchronized with each other, a density and arrangement of needles embedded on the needle blade rolls are optionally selected and the film is split without tearing and opening to make a split film having a network structure. Then the split film is cut into an optional length in the longitudinal direction and further the linkage in the network structure is cut with an opening machine such as a carding machine.
This method is a method of enabling split yarns to be made into staple fibers. The obtained fibers usually have the following characteristics.
Branch: At least one branch, preferably two or more branches are present on one fiber (filament).
Crimping: The number of crimps is preferably from 1 to 15/20 mm fiber length.
Fiber length: Fiber length can be determined optionally by selecting a cutting length, and is usually from 2 to 200 mm.
Fineness: 2 to 200 deniers
The heat-meltable fluorine-containing resin fibers of the present invention have a branched structure and therefore are excellent in intermingling property. One or two or more heat-meltable fluorine-containing resin fibers or a mixture of those fibers with one or more other fibers are useful as a material for various fiber products.
Examples of the form of material for fiber products are the forms of starting material such as yarn, web and cotton-like material, the forms of product such as woven fabric, knitted fabric, non-woven fabric, multi-layer felt, paper sheet and rope, and the like. Particularly preferred are web, non-woven fabric, multi-layer felt and paper sheet.
As a spinning method, a known processing method with a spinning machine can be adopted.
As a method for making a web, for example, a known method by using a carding machine can be adopted.
As a method for making a cotton-like material, for example, an air-lay method of simply accumulating fibers can be adopted.
A woven fabric can be obtained from known weaving method by using the above-mentioned yarns.
As a method for making a non-woven fabric, known methods, for example, needle punching method, water jet method, thermal bonding method, stitch bonding method, powder bonding method and the like can be employed.
A multi-layer felt can be obtained by overlaying the fibers of the present invention in the form of web, cotton-like material or non-woven fabric on a base fabric comprising a woven fabric or non-woven fabric and then intermingling the base fabric with a web or the like through needle punching method,
Asano Jun
Tamaru Shinji
Yamamoto Katsutoshi
Daikin Industries Ltd.
Edwards Newton
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