US4029835A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Heat resistant sheet
Assignee: Mitsubishi Chemical Corp
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Filing: 1976-01-14
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Granted: 1977-06-14
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Expires: 1996-01-14
Abstract
Abstract A novel heat resistant sheet having excellent varnish impregnability, a high dielectric strength and a high physical strength is obtained by pressing and heating a mixed web of wholly-aromatic polyamide fibers [A] having tan delta (max) >/= 0.25 and Es < 130 g/d and wholly-aromatic polyamide fibers [B] having tan delta (max) </= 0.2 and Es >/= 130 g/d under such conditions as said fibers [A] being heat fused.
Inventors
- 👤 Hiroshi Iwata
- 👤 Mikio Yoshida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 13:47
CPC Classifications
H; H01; H01B; H01B3/00; H01B3/18; H01B3/48; H01B3/485; D; D04; D04H; D04H1/00; D04H1/40; D04H1/54; D21; D21H; D21H13/00; D21H13/10; D21H13/20; D21H13/26; Y; Y10; Y10S; Y10S428/00; Y10S428/91; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/31504; Y10T428/31725; Y10T442/00; Y10T442/60; Y10T442/69; Y10T442/692
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
83 words
A heat resistant sheet produced by pressing and heating a mixed web of wholly aromatic polyamide fibers [A] having a maximum loss tangent tan δ(max) ≧ 0.25 and a sonic modulus Es < 130 g/d and wholly-aromatic polyamide fibers [B] having a maximum loss tangent tan δ(max) ≦ 0.2 and a sonic modulus Es < 130 g/d at a temperature of from 200° to 350° C and a pressure of not more than 200 kg/cm 2 wherein said fibers [A] are heat fused.
Claim 2
Dependent Claim
83 words
A heat resistant sheet produced by pressing and heating a mixed web of wholly aromatic polyamide fibers [A] having a maximum loss tangent tan δ(max) ≧ 0.25 and a sonic modulus Es < 130 g/d and wholly-aromatic polyamide fibers [B] having a maximum loss tangent tan δ(max) ≦ 0.2 and a sonic modulus Es < 130 g/d at a temperature of from 200° to 350° C and a pressure of not more than 200 kg/cm 2 wherein said fibers [A] are heat fused.
Claim 3
Dependent Claim
21 words
A heat resistant sheet according to claim 1, wherein the wholly-aromatic polyamide of both the fibers [A] and [B] is polymetaphenyleneisophthalamide.
Claim 4
Dependent Claim
40 words
A heat resistant sheet according to claim 1, wherein the wholly-aromatic polyamide of the fibers [A] is a copolymer wherein at least 80 mol % of repeating unit is metaphenyleneisophthalamide and the wholly-aromatic polyamide of the fibers [B] is polymetaphenyleneisophthalamide.
Claim 5
Dependent Claim
27 words
A heat resistant sheet according to claim 3, wherein said copolymer is a polycondensate of isophthalic acid chloride/terephthalic acid chloride = 90/10 (in molar ratio) and metaphenylenediamine.
Claim 6
Dependent Claim
24 words
A heat resistant sheet according to claim 1, wherein the mixing ratio of the fibers [A] and the fibers [B] is 1:4 - 4:1.
Claim 7
Dependent Claim
17 words
A heat resistant sheet according to claim 1 which has a void ratio of 30 - 70%.
Claim 8
Dependent Claim
17 words
An insulating sheet comprising the heat resistant sheet according to claim 1, impregnated with an insulating varnish.
References Cited (Backward Citations)
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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) | 1980-06-13 | 1980-12-13 | 1981-06-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-06-13 | 1984-12-13 | 1985-06-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-06-13 | 1988-12-13 | 1989-06-14 | $7700.00 | Window Closed / Lapsed |