Claims
- 1. A process for producing microporous tubes which comprises
- molding a polytetrafluoroethylene resin containing a liquid lubricating agent by a paste method to form a tube,
- removing the liquid lubricating agent,
- stretching by drawing the tube in a lengthwise direction using a die and a plug, and
- sintering at a temperature of about 327.degree. C. or more
- whereby as a result of said stretching and said drawing, a microporous tube is produced having a porosity and a bubble point in a range between the point A, B, C and D defined in the following table;
- ______________________________________ porosity bubble point______________________________________A 96% 0.02 kg/cm.sup.2B 54% 2.0 kg/cm.sup.2C 20% 2.0 kg/cm.sup.2D 30% 1.0 kg/cm.sup.2______________________________________
- and having a ratio of wall thickness to inside diameter of about 0.1 or less.
- 2. A process for producing microporous tubes as set forth in claim 1, wherein the stretching in the lengthwise direction is carried out two or more times and the final stretching is carried out by drawing using the die and the plug.
- 3. A process for producing microporous tubes as set forth in claim 1 which comprises sintering the tube at about 327.degree. C. or more simultaneously with expanding the tube by reducing the pressure on the outside of the tube after carrying out stretching by drawing.
Priority Claims (1)
Number |
Date |
Country |
Kind |
51-110536 |
Sep 1976 |
JPX |
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Parent Case Info
This is a Division of application Ser. No. 832,267, filed Sept. 12, 1977 now U.S. Pat. No. 4,177,334.
US Referenced Citations (5)
Divisions (1)
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Number |
Date |
Country |
Parent |
832267 |
Sep 1977 |
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