Microporous tubes
AssigneeSumitomo Electric Industries, Ltd.
InventorKoichi Okita
Life of this patent
Estimating the term…
Abstract
Polytetrafluoroethylene resin tubes having small pore size and high porosity are produced by a process which includes stretching the tubes by drawing using a metal die and a metal plug. By using the die and plug, the stress necessary for stretching is converted to a compressive force in the thickness direction of the tube. This compressive force is an essential factor in producing the microporous structure of the tubes. In addition, when stretching is performed by drawing, a ratio of thickness to inside diameter of the tube of 0.07 or less can be easily achieved.
Claims5
A microporous tube composed of a porous polytetrafluoroethylene resin comprising nodules linked to one another by fine filaments prepared by molding a polytetrafluoroethylene resin containing a liquid lubricating agent by a paste method to form a tube, removing said liquid lubricating agent, stretching by drawing said tube in a lengthwise direction using a die and a plug, and sintering at a temperature of about 327.degree. C. or more, said microporous tube (a) having a porosity and a bubble point in a range between the points A, B, C and D in FIG. 1 and defined in the following table:
- ______________________________________ porosity bubble point ______________________________________ A 96% 0.02 kg/cm.sup.2 B 54% 2.0 kg/cm.sup.2 C 20% 2.0 kg/cm.sup.2 D 30% 1.0 kg/cm.sup.2 ______________________________________
- and (b) having a ratio of wall thickness to inside diameter of about 0.1 or less.
Dependencies are inferred from the claim text.