Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including interlaminar mechanical fastener
Patent
1982-02-08
1984-06-12
Cannon, James C.
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including interlaminar mechanical fastener
19296, 28104, 28107, 28116, 28122, 264176F, 2642102, 264280, 264324, 428288, 428290, 428339, 428340, 428364, 428369, 428401, 528388, D01D 510, D04H 310
Patent
active
044541899
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
Technical Field
The present invention relates to a fibrous sheet which is superior in heat resistance, chemical resistance, flame retardancy, electrical insulating properties, and strength. More particularly, the invention relates to a fibrous sheet of polyphenylene sulfide (referred to as PPS hereinafter) filaments and a process for producing the same.
Background Art
PPS is known as a thermoplastic polymer having superior chemical resistance and heat resistance, as disclosed in U.S. Pat. No. 3,912,695. That PPS is also capable of being melt spun is disclosed in Japanese Patent Publication Nos. 52-12240 (1977) and 52-30609 (1977). In practice, however, it is impossible to produce invariably PPS filaments of uniform quality. In other words, PPS polymer having a viscosity suitable for melt spinning is liable to form particulate gels which cause quite often breakage of filaments during spinning and drawing. This tendency is pronounced in the case of fine filaments. On the other hand, if the viscosity is lowered to avoid gelation, the resulting PPS polymer is so poor in spinnability and so brittle that the filaments spun from such PPS polymer are easily broken by friction with guides. Furthermore, such PPS filaments produced by some means or other are stiff, liable to static build-up, slippery, lacking the bunching property and even twisting and doubling are difficult to perform, not to mention crimping. It is also difficult to make a uniform sheet from such PPS filaments by knitting, weaving, or carding. In addition, PPS fibers do not disperse very well into water because they are extremely hydrophobic. This makes PPS fibers unsuitable for making sheets therefrom in the papermaking manner. Such being the case, fibrous sheets of PPS polymer having high strength and uniform quality have not been produced easily.
Disclosure of Invention
The present invention discloses the following.
1. A sheet of PPS filaments which comprises randomly dispersed and accumulated PPS filaments, each having a fineness of 0.1 to 15 denier.
2. A process for producing a sheet of PPS filaments which comprises extruding a PPS polymer from a plurality of small holes at a temperature 20.degree. to 85.degree. C. higher than the melting point of the PPS polymer, drawing apart the extrudate from the small holes at a rate greater than 1300 m/min by a high-velocity air stream, simultaneously causing the resulting filaments to be separated by electrostatic charge, collecting the separated filaments on a plane, and bonding or interlocking the collected filaments.
Best Mode for Carrying Out the Invention
According to the process of this invention for producing a sheet of PPS filaments, a molten PPS polymer is extruded from small holes and then the extrudate is conveyed by an air stream, without contact with guides and rollers. This makes it possible to produce a fibrous sheet without frequent breakage of filaments and troubles of broken filaments being caught in rollers. More specifically, the fluid extrudate is introduced to the inside of an annular air jet or the outside of a cylindrical air jet so that the extrudate is drawn apart from the small holes. In another way, the molten polymer is extruded from small holes into a pressurized compartment and the extrudate is blown out at a high speed together with a pressurized fluid ejected from the nozzle opposite to the small holes. The spinning speed should be at least 1300 m/min, preferably 3000 m/min and over. It is not difficult to realize a spinning speed greater than 5000 m/min, if the above-mentioned method is employed. According to the process mentioned above, it is possible to produce fibers having a strength greater than 1.5 g/d and a dry heat shrinkage of 5 to 40% at 140.degree. C. The spinning temperature should be 20.degree. C., preferably 30.degree. to 60.degree. C., higher than the melting point of the polymer. The small holes have a diameter from 0.1 to 1.0 mm, and the number of the small holes is usually greater than ten. The distance between the small holes
REFERENCES:
patent: 3354129 (1967-11-01), Edmonds et al.
patent: 3895091 (1975-07-01), Short et al.
patent: 3912695 (1975-10-01), Short et al.
Cannon James C.
Miller Austin R.
Toray Industries Inc.
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