Claims
- 1. A method of producing an easily splittable oriented film comprising the steps of:
- dissolving a raw material mixture containing nylon and meta-xylylene adipamide at a weight ratio of 40-85:60-15;
- extruding the dissolved raw material mixture in an extruder to obtain a raw film;
- biaxially orienting the raw film in a machine direction and a transverse direction at an orientation ratio of at least 2.8 by a tubular method by heating a side portion of the film at a lower temperature than another portion of the film while folding the film;
- folding the biaxially oriented film flat; and
- thermally treating the biaxially oriented film.
- 2. The method of claim 1, additionally comprising a step of kneading the dissolved raw material mixture at a temperature up to 300.degree. C. prior to the extrusion step.
- 3. The method of claim 1, wherein the heating step is performed by a plurality of heaters provided around the film and the temperature of the heater that heats the side portion of the film is 10-100.degree. C. lower than the average temperature of all the heaters.
- 4. The method of claim 1, wherein the heating temperature at an edge of the side portion of the film is at a minimum and the heating temperature at the center of the other portion of the folded film is at a maximum.
- 5. The method of claim 1, wherein the heating is performed in two stages, a first stage of heating by a tubular method at a temperature of 120-190.degree. C. and a second stage of heating by a tenter method at a temperature of 190-220.degree. C.
- 6. The method of claim 1, wherein the thermal treatment is performed in two stages, a first stage comprising the steps of holding the side portions according to a tenter method, heating the film at a temperature between 120-190.degree. C. and at a relaxation ratio of no more than 15%, and cutting the side portions to form two films, and a second stage comprising holding the side portions of the two films according to a tenter method and heating the films at a temperature between 190-220.degree. C. and at a relaxation ratio of no more than 15% while air is introduced between the films.
Priority Claims (2)
Number |
Date |
Country |
Kind |
3-308427 |
Oct 1991 |
JPX |
|
3-313675 |
Oct 1991 |
JPX |
|
Parent Case Info
This is a division of Ser. No. 07/967,249, filed Oct. 27, 1992 now U.S. Pat. No. 5,541,011.
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3678546 |
Matsugu et al. |
Jul 1972 |
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3946089 |
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Mar 1976 |
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4978484 |
Takashige et al. |
Dec 1990 |
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5094799 |
Takashige et al. |
Mar 1992 |
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5158637 |
Takashige et al. |
Oct 1992 |
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Number |
Date |
Country |
2635164 |
Apr 1977 |
DEX |
51-90370 |
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JPX |
56-62129 |
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58-158224 |
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Divisions (1)
|
Number |
Date |
Country |
Parent |
967249 |
Oct 1992 |
|