Appeal No. 2001-0344
Application 08/900,254
using a profiled calender roll. This is said to result in the bonding of the fibrous web in a
“tension-free” manner without inhomogeneities or flat bonding. The resulting three-
dimensional structure is said to be stable and may form the basis for a later pleating
operation to form a pleated filter.
CLAIMS ON APPEAL
1. A method for manufacturing a pleated filter material from a thermally
bonded non-woven fabric, comprising:
forming a single fibrous web from drawn and undrawn synthetic fibers;
calendering only the single fibrous web in a single calendering step,
wherein during the single calendering step, the undrawn fibers in the single fibrous web
are bonded in a tension-free manner between profiled calender rolls to form the non-
woven fabric, without inhomogeneities over the cross-section of the non-woven fabric
and without the use of flat bonding, and wherein during the single calendering step,
spacers are formed in the non-woven fabric to thereby form a filter material.
2. The method of claim 1, further comprising:
preheating the fibrous web and then guiding the fibrous web between
heater calender rolls during the single calendering step.
3. The method of claim 1, further comprising:
preheating the fibrous web and then guiding the fibrous web between
cooled calender rolls during the single calendering step.
4. The method of claim 1, further comprising:
guiding the fibrous web, unheated, between heated calender rolls during
the single calendering step.
THE REFERENCES
The prior art references relied on by the examiner are:
Norton (Norton) 2,862,542 Dec. 02, 1958
Yamamoto et al. (Yamamoto) 4,496,583 Jan. 29, 1985
Naruo et al. (Naruo) 4,876,007 Oct. 24, 1989
Meyer 5,232,595 Aug. 03, 1993
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