Claims
- 1. A process for the production of a filter having an inlet side and an outlet side and comprising fibers bonded to each other with a binder, said filter having a fiber density of 0.01 to 0.1 at the inlet side and a fiber density of 0.05 to 0.5 at the outlet side and having a continuous fiber density gradient from the inlet side to the outlet side while having a uniform distribution of the different types of fibers, comprising the steps of:
- drawing a gas, containing a powdery binder having a particles size of 1 to 150.mu., by suction through webs having a fiber density of 7.times.10.sup.-4 to 1.times.10.sup.-2 at a flow rate of not more than 4 m/second, thereby adhering the binder to the fibers of the webs in an amount of 10 to 80% by weight to the total weight of webs so that the adhered amount of the binder is rich at the inlet side and is poor at the outlet side;
- hot-pressing the binder-containing webs at a fiber density of not higher than 0.2; and
- recovering the webs from the pressing.
Priority Claims (1)
Number |
Date |
Country |
Kind |
55-159959 |
Nov 1980 |
JPX |
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Parent Case Info
This is a continuation of application Ser. No. 627,586 filed on July 3, 1984, abandoned, which is a division of application Ser. No. 522,248 filed Aug. 10, 1983, abandoned, which is a continuation of application Ser. No. 320,984, filed Nov. 12, 1981, abandoned.
US Referenced Citations (8)
Foreign Referenced Citations (2)
Number |
Date |
Country |
0499186 |
Jan 1954 |
CAX |
2905423 |
Aug 1980 |
DEX |
Divisions (1)
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Number |
Date |
Country |
Parent |
522248 |
Aug 1983 |
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Continuations (2)
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Number |
Date |
Country |
Parent |
627586 |
Jul 1984 |
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Parent |
320984 |
Nov 1981 |
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