Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1993-04-30
1995-02-07
Johnstone, Adrienne
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
139387R, 139388, 139420A, 1563082, 264103, 264127, 264147, B29C 6704, B29D 3100, B03D 302, B03D 1500
Patent
active
053873009
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of manufacturing a seamless tubular article which comprises weaving a seamless tubular fabric using a polytetrafluoroethylene yarn.
BACKGROUND ART
Prior Art
By assembling a warp yarn and a filling yarn in the manner of a circular or hollow wave, a radially seamless tubular fabric can be manufactured. The chief material of such warp and filling yarns is a polyester or a nylon. This seamless tubular fabric can be sliced at appropriate widths in the radial direction to provide loop-like seamless belts. The seamless belts thus obtained find application as conveyor belts, transmission belts, impact printer ink ribbon substrates and so on.
It is also a known technology to impregnate or coat such a seamless tubular fabric (or a loop-shaped seamless belt obtained by slicing it) with a resin and the present applicants also have filed several patent applications, viz.
Japanese Patent Kokai No. 61-40145 discloses a tubular article manufactured by impregnating or coating a hollow fabric woven from warp and filling yarns with a resin. However, fluorine-containing resins are not mentioned as examples of the resin.
Japanese Patent Kokai No. 64-46087 discloses a circular-woven seamless hose formed with bellows and treated with a resin and includes a cursory mention of fluororesins as the resin to be used for such resin treatment.
A polytetrafluoroethylene powder having a primary particle diameter of about 0.2 to 0.3 .mu.m and a secondary particle diameter of about 300 to 600 .mu.m which has been separated and granulated from a dispersion prepared by the emulsion polymerization of tetrafluoroethylene is known as fine powder. This fine powder can be easily formed into fiber with a small shear force and absorbs an organic solvent, such as naphtha or white oil, efficiently to give a paste. So, as this paste is extruded to provide a preliminary molding in the shape of a round bar or a sheet which is then compressed by means of rolls to remove the solvent before spontaneous evaporation of the solvent, there is obtained a film known as green tape. The green tape thus obtained has been used commonly as a sealing material for the water pipe and other pipe joints. When sintered, the green tape gives a transparent film.
A dispersion of polytetrafluoroethylene is an aqueous colloidal suspension containing a nonionic surfactant. As a cloth such as glass cloth, carbon fiber cloth or an aromatic polyamide fiber cloth is repeatedly dipped in this dispersion, dried and sintered, there is obtained an electrical insulation tape or a tape for non-bonding applications.
Problems That the Invention is to Solve
The technologies of impregnating or coating a seamless tubular fabric with a resin as disclosed in JP Kokai No. 61-40145 and JP Kokai No. 64-46087 referred to above comprise a mere disposition of a resin impregnation layer or a resin coating layer in or on the seamless tubular fabric and, therefore, even when an aqueous dispersion of polytetrafluoroethylene is used as the resin, the improvement in surface characteristics is self-limited.
In the polytetrafluoroethylene dispersion treatment of a cloth such as glass cloth or carbon fiber cloth, application of the dispersion in a thick layer gives rise to mad cracks. Therefore, it is imperative to limit the amount of deposition per dose to about 20 .mu.m or less in terms of sintered resin thickness and repeat the dip-dry-sinter cycle 5 to 10 times (usually 7-8 times) to obtain the required thickness. However, such a multi-cycle procedure involves much labor, time and thermal energy with the result that a marked decrease in productivity as well as a cost increase are inevitable.
Under the circumstances, the object of the present invention is to provide a method of manufacturing a seamless tubular article whose texture itself is made up of polytetrafluoroethylene through the employment of polytetrafluoroethylene yarn.
SUMMARY OF THE INVENTION
The method of manufacturing a seamless tubular article according to this invention
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