US5409766A
Expired / Lapsed
US
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Nonwoven fabric in an electret state and process for its production
Assignee: Mitsui Chemicals Inc
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Filing: 1993-10-18
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Granted: 1995-04-25
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Expires: 2013-10-18
Abstract
Abstract The improved nonwoven fabric in an electret state is composed of monofilaments with an average fiber diameter of 0.5-100 μm that are formed of a polymer composition containing no more than 1 mol % of polar groups; the fabric has a weight of 5-100 g/m 2 , a bulk density of 0.05-0.40 g/cm 3 and an average surface charge density of at least 0.1×10 -9 C/cm 2 . This nonwoven fabric is capable of efficient dust collection and its trapping ability is retained for a prolonged time even in a hot and humid condition. Also disclosed are a process for producing this nonwoven fabric, as well as a filtering and an air masking material which are composed of that nonwoven fabric.
Inventors
- 👤 Haruo Yuasa
- 👤 Masayuki Mito
- 👤 Yukihiro Takata
- 👤 Satoshi Matsuura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 03:38
CPC Classifications
D; D01; D01F; D01F6/00; D01F6/44; D01F6/46; D04; D04H; D04H1/00; D04H1/40; D04H1/42; B; B01; B01D; B01D39/00; B01D39/14; B01D39/16; B01D39/1607; B01D39/1623; D01D; D01D10/00; D01D5/00; D01D5/08; D01D5/098; D01D5/0985; D01F6/28; D01F6/30; D04H1/4282; D04H1/4291; D04H1/54; D04H1/56; D04H3/00; D04H3/005; D04H3/007; D04H3/08; D04H3/16; Y; Y10; Y10S; Y10S428/00; Y10S428/903; Y10S55/00; Y10S55/39; Y10T; Y10T442/00; Y10T442/60; Y10T442/637; Y10T442/68
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
70 words
A nonwoven fabric in an electret state that is composed of monofilaments of a polymer composition that contains no more than 1 mol % of polar groups, said monofilaments having an average fiber diameter of 0.5-100 μm and said nonwoven fabric having a weight of 5-100 g/m 2 , a bulk density of 0.05-0.40 g/cm 3 and an average surface charge density of at least 0.1×10 -9 C/cm 2 .
Claim 2
Dependent Claim
70 words
A nonwoven fabric in an electret state that is composed of monofilaments of a polymer composition that contains no more than 1 mol % of polar groups, said monofilaments having an average fiber diameter of 0.5-100 μm and said nonwoven fabric having a weight of 5-100 g/m 2 , a bulk density of 0.05-0.40 g/cm 3 and an average surface charge density of at least 0.1×10 -9 C/cm 2 .
Claim 3
Dependent Claim
26 words
A nonwoven fabric in an electret state according to claim 1 wherein a content of said polar groups in said polymer composition is 0.03-0.1 mol %.
Claim 4
Dependent Claim
23 words
A nonwoven fabric in an electret state according to claim 1 wherein said polymer composition has an intrinsic viscosity [η] of 0.3-1.5 dl/g.
Claim 5
Dependent Claim
107 words
A nonwoven fabric in an electret state according to claim 1 wherein said polymer composition is at least one member selected from the group consisting of: (A) a copolymer consisting of a monomer having polar groups and a nonpolar monomer; (B) a polymer having polar groups introduced into side chains or the backbone chain of a nonpolar polymer by means of oxidation or halogenation; (C) a graft modified polymer having a polar group containing monomer graft copolymerized onto a nonpolar polymer or said polymer (B); and (D) a mixture of a nonpolar polymer and at least one member selected from among said polymers (A), (B) and (C).
Claim 6
Dependent Claim
38 words
A nonwoven fabric in an electret state according to claim 4 wherein said polar groups are halogen atoms, carbonyl groups, nitro groups and at least one member selected from among the groups represented by the following formulae: ##STR2##
Claim 7
Dependent Claim
26 words
A nonwoven fabric in an electret state according to claim 4 wherein said polymer composition contains both a polar group containing polymer and a nonpolar polymer.
Claim 8
Dependent Claim
30 words
A nonwoven fabric in an electret state according to claim 6 wherein said polar group containing polymer contains polar groups in an amount of no more than 3 mol %.
Claim 9
Dependent Claim
38 words
A nonwoven fabric in an electret state according to claim 1 wherein said polymer composition is a polyolefin that has been modified with at least one modifying monomer as selected from among unsaturated carboxylic acids and derivatives thereof.
Claim 10
Dependent Claim
29 words
A nonwoven fabric in an electret state according to claim 8 wherein said polymer composition contains said modifying monomer in an amount of no more than 1 mol %.
Claim 11
Dependent Claim
19 words
A nonwoven fabric in an electret state according to claim 8 wherein said modified polyolefin is a modified polypropylene.
Claim 12
Dependent Claim
53 words
A nonwoven fabric in an electret state according to claim 8 wherein said modified polyolefin contains 98-40 wt % of polypropylene (a) and 2-60 wt % of an ethylene-α-olefin copolymer (b) having a crystallinity of less than 40% as measured with X-rays, with the sum of (a) and (b) being 100 wt %.
Claim 13
Dependent Claim
45 words
A nonwoven fabric in an electret state according to claim 1 wherein said polymer composition contains not only a polyolefin that has been modified with at least one modifying monomer as selected from among unsaturated carboxylic acids and derivatives thereof but also an unmodified polyolefin.
Claim 14
Dependent Claim
17 words
A nonwoven fabric in an electret state according to claim 12 wherein said unmodified polyolefin is polypropylene.
Claim 15
Dependent Claim
53 words
A nonwoven fabric in an electret state according to claim 12 wherein said unmodified polyolefin contains 98-40 wt % of polypropylene (a) and 2-60 wt % of an ethylene-α-olefin copolymer (b) having a crystallinity of less than 40% as measured with X-rays, with the sum of (a) and (b) being 100 wt %.
Claim 16
Dependent Claim
51 words
A process for producing a nonwoven fabric in an electret state, which comprises the steps of forming a polymer composition containing no more than 1 mol % of polar groups into a nonwoven fabric by a melt-blow method and then applying a DC voltage to the nonwoven fabric to create electrets.
Claim 17
Dependent Claim
51 words
A process for producing a nonwoven fabric in an electret state, which comprises the steps of forming a polymer composition containing no more than 1 mol % of polar groups into a nonwoven fabric by a melt-blow method and then applying a DC voltage to the nonwoven fabric to create electrets.
Claim 18
Dependent Claim
32 words
A process according to claim 15 wherein said polymer composition is a polyolefin that has modified with at least one modifying monomer as selected from among unsaturated carboxylic acids and derivatives thereof.
Claim 19
Dependent Claim
40 words
A process according to claim 15 wherein said polymer composition contains not only a polyolefin that has been modified with at least one modifying monomer as selected from among unsaturated carboxylic acids and derivatives thereof but also an unmodified polyolefin.
Claim 20
Dependent Claim
19 words
A filtering material that is composed of a nonwoven fabric in an electret state as recited in claim 1.
Claim 21
Dependent Claim
20 words
An air masking material that is composed of the nonwoven fabric in an electret state as recited in claim 1.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-04-24 | 1998-10-24 | 1999-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-04-24 | 2002-10-24 | 2003-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-04-24 | 2006-10-24 | 2007-04-25 | $7700.00 | Window Closed / Lapsed |