US4818342A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Heat treatment of paper products
Assignee: International Paper Co
•
Filing: 1987-09-30
•
Granted: 1989-04-04
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Expires: 2007-09-30
Abstract
Abstract The stiffness and wet strength of paper products are improved by subjecting the products to high temperature treatment, immediately followed by rewetting. The resultant products have good folding endurance.
Inventors
- 👤 Dinkar G. Wagle
- 👤 Vacheslav M. Yasnovsky
- 👤 Jerome M. Floyd
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:01
CPC Classifications
D; D21; D21H; D21H25/00; D21H25/04; D21H25/06; D21F; D21F11/00; D21H5/00; D21H5/12; D21H5/1272; D21H5/129
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
78 words
A method of improving the stiffness and strength of a kraft paper product while maintaining acceptable flexibility thereof comprising steps of heat treating incompletely dried or moisturized paper product, at high temperature within the range of 284° F. to 482° F. for 0.5 seconds to 120 seconds, and then rewetting the surface of said product immediately following said heat treating step, said product being maintained above 212° F. during the interval between the heat treating and rewetting steps.
Claim 2
Independent Claim
78 words
A method of improving the stiffness and strength of a kraft paper product while maintaining acceptable flexibility thereof comprising steps of heat treating incompletely dried or moisturized paper product, at high temperature within the range of 284° F. to 482° F. for 0.5 seconds to 120 seconds, and then rewetting the surface of said product immediately following said heat treating step, said product being maintained above 212° F. during the interval between the heat treating and rewetting steps.
Claim 3
Dependent Claim
27 words
The method of claim 1, wherein the product has an initial moisture content in the range of 1.0 to 40% by weight before said heat treating step.
Claim 4
Dependent Claim
27 words
The method of claim 1, wherein during the rewetting step, the product is rewetted to a moisture content in the range of 1.0 to 20% by weight.
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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) | 1992-04-03 | 1992-10-03 | 1993-04-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-03 | 1996-10-03 | 1997-04-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-03 | 2000-10-03 | 2001-04-04 | $7700.00 | Window Closed / Lapsed |