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US 9,441,327 B2Granted
Dimensionally stable paper and production method thereof
AssigneeA. Ahlstrom Corporation
InventorsBernd Ullmann, Holger Arnold
Life of this patent
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Abstract
A dimensionally stable paper and paper products, a production method for such paper, and uses of substances for conveying, modifying or improving dimensional stability of paper.
Claims18
A method of producing a paper having good dimensional stability, comprising the steps of:
- I. producing of a water-based impregnation mixture comprising at least
- a sugar alcohol having a general formula HOCH2[CH(OH)]nCH2OH wherein n=2, 3, 4 or 5,
- a urea,
- a polyalkylene glycol and/or glycerin, and
- a) a latex dispersed in the mixture, wherein the impregnation mixture has a pH of more than 7, or
- b) a dry strength agent, wherein the impregnation mixture has a pH of at least 6 and at most 7,
- II. lowering of the pH of the impregnation mixture to at most 5.5 by addition of a coagulant releasing aluminum ions, and
- III. raising the pH at least to the values indicated in step I) for alternative a) or b), respectively, and
- IV. impregnating a raw paper with the impregnation mixture of step III).
6 more elements
A method for producing a paper having good dimensional stability, comprising the steps of:
- I. producing a water based impregnation mixture comprising:
- a sugar alcohol having a general formula HOCH2[CH(OH)]nCH2OH wherein n=2, 3, 4 or 5;
- a urea;
- and
- a polyalkylene glycol and/or glycerin;
- II. impregnating a raw paper with the impregnation mixture;
- III. producing of a water-based impregnation mixture comprising at least:
- a sugar alcohol having a general formula HOCH2[CH(OH)]nCH2OH wherein n=2, 3, 4 or 5;
- a urea;
- and
- a polyalkylene glycol and/or glycerin;
- and
- a) a latex dispersed in the mixture, wherein the impregnation mixture has a pH of more than 7;
- or
- b) a dry strength agent, wherein the impregnation mixture has a pH of at least 6 and at most 7;
- IV. lowering of the pH of the impregnation mixture of step III) to at most 5.5 by addition of a coagulant releasing aluminum ions;
- and
- V. raising the pH of the impregnation mixture of step IV) at least to the values indicated in step III) for alternative a) or b), respectively, and
- VI. impregnating a raw paper with the impregnation mixture of step V).
16 more elements
Dependencies are inferred from the claim text.