US4056432A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for making paper products of improved dry strength
Assignee: ECC SPECIALTY CHEMICALS Inc
•
Filing: 1971-07-06
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Granted: 1977-11-01
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Expires: 1991-07-06
Abstract
Abstract Paper products exhibiting markedly improved dry strength properties are produced by adding to the cellulose paper dispersion a chitin-based compound comprising chitosan alone or a graft copolymer of certain acrylic and/or diallylic monomers grafted onto the chitosan as a substrate.
Inventors
- 👤 Robert Clayton Slagel
- 👤 Gloria DiMarco Sinkovitz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:41
CPC Classifications
D; D21; D21H; D21H17/00; D21H17/20; D21H17/21; D21H17/24
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
75 words
An improved process for making paper having dry strength comprising forming an aqueous suspension of papermaking cellulosic fibers, adding to said suspension a dry strength additive, sheeting the fibers to form a web and heating the web until dry to form the paper, wherein the improvement comprises using as the dry strength additive, a graft copolymer comprising from 5 to 99.5 percent by weight of a chitosan substrate and the remainder derived from acrylamide monomer.
Claim 2
Dependent Claim
75 words
An improved process for making paper having dry strength comprising forming an aqueous suspension of papermaking cellulosic fibers, adding to said suspension a dry strength additive, sheeting the fibers to form a web and heating the web until dry to form the paper, wherein the improvement comprises using as the dry strength additive, a graft copolymer comprising from 5 to 99.5 percent by weight of a chitosan substrate and the remainder derived from acrylamide monomer.
References Cited (Backward Citations)
US2216845A
Cited
US2748029A
Cited
US3095391A
Cited
US3288770A
Cited
US3445556A
Cited
US3639208A
Cited
US3709780A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-10-31 | 1981-05-02 | 1981-11-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-10-31 | 1985-05-02 | 1985-11-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-10-31 | 1989-05-02 | 1989-11-01 | $7700.00 | Window Closed / Lapsed |