US4708891A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for manufacturing polishing cloths
Assignee: Toyo Cloth Co Ltd
•
Filing: 1986-02-24
•
Granted: 1987-11-24
•
Expires: 2006-02-24
Abstract
Abstract A method for manufacturing polishing cloths of the class to be used with abrasive powders on a lapping machine is disclosed. The method comprises the steps of impregnating a nonwoven fabric sheet with a solution of polyurethane elastomer, wet-coagulating the impregnated sheet, and heating the resulting microporous composite sheet at a temperature higher than the softening point of the polyurethane elastomer under an essentially uncompressed condition.
Inventors
- 👤 Hajime Ito
- 👤 Junichi Miwa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 23:35
CPC Classifications
D; D06; D06N; D06N3/00; D06N3/007; D06N3/0075; D06M; D06M15/00; D06M15/19; D06M15/37; D06M15/564; D06N3/0072; D06N3/04; D06N3/042; D06N3/045; D06N3/12; D06N3/14; D06N2205/00; D06N2205/10
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
112 words
A method for producing a polyurethane-based polishing cloth which comprises the steps of: impregnating, with a solution containing a polyurethane elastomer, a nonwoven fabric sheet made of a synthetic fiber having a melting point higher than that of said polyurethane elastomer; wet-coagulating the resulting impregnated sheet to form a microporous composite sheet; and heating the resulting composite sheet in an essentially uncompressed condition at a temperature higher than the softening point of the polyurethane elastomer and lower than the melting point of the synthetic fiber for a sufficient length of time to impart to the sheet a degree of hardness greater than 80 and an air-permeability greater than 25 cc/cm 2 /second.
Claim 2
Independent Claim
112 words
A method for producing a polyurethane-based polishing cloth which comprises the steps of: impregnating, with a solution containing a polyurethane elastomer, a nonwoven fabric sheet made of a synthetic fiber having a melting point higher than that of said polyurethane elastomer; wet-coagulating the resulting impregnated sheet to form a microporous composite sheet; and heating the resulting composite sheet in an essentially uncompressed condition at a temperature higher than the softening point of the polyurethane elastomer and lower than the melting point of the synthetic fiber for a sufficient length of time to impart to the sheet a degree of hardness greater than 80 and an air-permeability greater than 25 cc/cm 2 /second.
Claim 3
Dependent Claim
27 words
The method according to claim 1, wherein said heating step is carried out at a temperture from 180° C. to 250° C. for 2 to 45 minutes.
Claim 4
Dependent Claim
30 words
The method according to claim 1, wherein said nonwoven fabric sheet has a thickness from 2 to 10 mm and a basis weight from 300 to 1500 g/m 2 .
Claim 5
Dependent Claim
30 words
The method according to claim 1, wherein said polyurethane solution additionally contains up to equal parts by weight of the polyurethane elastomer of polyvinyl chloride, polymethyl methacrylate or styrene-acrylonitrile rubber.
Claim 6
Dependent Claim
30 words
The method according to claim 1 further including the step of slicing the microporous composite sheet adjacent its opposite surfaces to remove skin layers before or after said heating step.
Claim 7
Dependent Claim
28 words
The method according to claim 5 further including, after removal of said skin layers, the step of slicing the microporous composite sheet remainder into two or more sheets.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-11-23 | 1991-05-25 | 1991-11-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-11-23 | 1995-05-25 | 1995-11-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-11-23 | 1999-05-25 | 1999-11-24 | $7700.00 | Window Closed / Lapsed |