Patent US4818341A successfully refreshed from Google Patents.
US4818341A
Expired / Lapsed
US
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Production of paper and paperboard of high dry strength
Assignee: BASF SE
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Filing: 1988-02-12
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Granted: 1989-04-04
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Expires: 2008-02-12
Abstract
Abstract Paper and paperboard of high dry strength are produced by adding a dry strength enhancer to the paper stock and dewatering the paper stock with sheet formation by using as the dry strength enhancer a mixture of a cationic polymer which contains as characteristic monomers copolymerized units of (a) diallyldimethylammonium chloride, (b) N-vinylamine or (c) a substituted or unsubstituted N-vinylimidazoline and has a K value of not less than 30, and natural potato starch which is converted into a water-soluble form by heating in an aqueous medium at above the gelatinization temperature of natural potato starch in the absence of any oxidizing agents or alkali.
Inventors
- 👤 Hans-Juergen Degen
- 👤 Sigberg Pfohl
- 👤 Volkmar Weberndoerfer
- 👤 Gerd Rehmer
- 👤 Michael Kroener
- 👤 Andreas Stange
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:19
CPC Classifications
D; D21; D21H; D21H17/00; D21H17/20; D21H17/21; D21H17/24; D21H17/28; D21H17/29; D21H17/33; D21H17/34; D21H17/41; D21H17/44; D21H17/45; D21H17/455; D21H5/00; D21H5/26; D21H5/265; D21H5/2657; D21H5/2664; D21H21/00; D21H21/14; D21H21/18
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
176 words
A process for producing paper and paperboard of high dry strength by adding a mixture of from 1 to 20 parts by weight of a cationic polymer which contains as characteristic monomers copolymerized units of (a) diallyldimethylammonium chloride, (b) N-vinylamine or (c) an N-vinylimidazoline of the formula ##STR8## where R 1 is H, C 1 -C 18 -alkyl or ##STR9## R 5 and R 6 are each H, C 1 -C 4 -alkyl or Cl, R 2 is H, C 1 -C 18 -alkyl, ##STR10## R 3 and R 4 are each H or C 1 -C 4 -alkyl and X - is an acid radical, and which has a K value of not less than 30, and 100 parts by weight of natural potato starch which is converted into a water-soluble form by heating in an aqueous medium at above the gelatinization temperature of natural potato starch in the absence of any oxidizing agent, polymerization initiator or alkali, as a dry strength enhancer to the paper stock and dewatering the paper stock with sheet formation.
Claim 2
Dependent Claim
176 words
A process for producing paper and paperboard of high dry strength by adding a mixture of from 1 to 20 parts by weight of a cationic polymer which contains as characteristic monomers copolymerized units of (a) diallyldimethylammonium chloride, (b) N-vinylamine or (c) an N-vinylimidazoline of the formula ##STR8## where R 1 is H, C 1 -C 18 -alkyl or ##STR9## R 5 and R 6 are each H, C 1 -C 4 -alkyl or Cl, R 2 is H, C 1 -C 18 -alkyl, ##STR10## R 3 and R 4 are each H or C 1 -C 4 -alkyl and X - is an acid radical, and which has a K value of not less than 30, and 100 parts by weight of natural potato starch which is converted into a water-soluble form by heating in an aqueous medium at above the gelatinization temperature of natural potato starch in the absence of any oxidizing agent, polymerization initiator or alkali, as a dry strength enhancer to the paper stock and dewatering the paper stock with sheet formation.
Claim 3
Dependent Claim
41 words
A process as claimed in of claim 1, wherein the dry strength enhancer used is a mixture obtainable by heating natural potato starch in the presence of a homopolymer of diallyldimethylammonium chloride having a K value of from 60 to 180.
Claim 4
Dependent Claim
62 words
A process as claimed in claim 1, wherein the dry-strength enhancer used is a mixture obtainable by heating natural potato starch in the presence of a homopolymer of N-vinylformamide in which from 70 to 100 mol % of the formyl groups on the polymer have been eliminated to form N-vinylamine units, the hydrolyzed polymer having a K value from 75 to 170.
Claim 5
Dependent Claim
109 words
A process as claimed in claim 1, wherein the dry-strength enhancer used is a mixture obtainable by heating natural potato starch in the presence of a hydrolyzed copolymer which contains (a) from 95 to 10 mol % of N-vinylformamide and (b) from 5 to 90 mol % of vinyl acetate or vinyl propionate as copolymerized units, from 70 to 100 mol % of the formyl groups in the polymer having been eliminated to form N-vinylamine units and from 70 to 100 mol % of the acetyl and propionyl groups having been eliminated to form vinyl alcohol units, and the hydrolyzed polymer having a K value from 70 to 170.
Claim 6
Dependent Claim
50 words
A process as claimed in claim 1, wherein the dry-strength enhancer used is a mixture obtainable by heating natural potato starch in the presence of a homopolymer of a substituted or unsubstituted N-vinylimidazoline or of a copolymer thereof with acrylamide and/or methacrylamide having a K value from 80 to 220.
Claim 7
Dependent Claim
69 words
A process as claimed in claim 1, wherein the dry-strength enhancer used is a mixture obtainable by heating natural potato starch in the presence of a copolymer comprising (a) from 70 to 96.5% by weight of acrylamide and/or methacrylamide, (b) from 2 to 20% by weight of N-vinylimidazoline or N-vinyl-2-methylimidazoline and (c) from 1.5 to 10% by weight of N-vinylimidazole and having a K value from 80 to 220.
References Cited (Backward Citations)
US3873336A
Cited
US4097427A
Cited
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 |