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    5.
    发明专利
    未知

    公开(公告)号：ES2063977T3

    公开(公告)日：1995-01-16

    申请号：ES90912409

    申请日：1990-08-22

    Applicant: BASF AG

    Inventor： FLORY KLAUS ,  STANGE ANDREAS ,  KROENER MICHAEL ,  SENDHOFF NORBERT

    IPC: C08G12/12 ,  C08G12/46 ,  D21H17/49 ,  D21H17/50

    Abstract: Cationic urea/formaldehyde resins are obtainable by condensing urea and formaldehyde in a molar ratio of from 1:1.5 to 1:3 in the presence of polymers which contain not less than 1 mol % of polymerized vinylamine units and have Fikentscher K values of from 5 to 300, in an amount of from 5 to 50 g per mole of urea in the end product, where the mixture is first a) precondensed at a pH of from 8 to 14, then acidified and b) condensed at a pH of from 1 to 5 until gel formation begins, c) then from 0.3 to 1.5 moles of formaldehyde are added per mole of urea used, d) post-condensation is carried out and e) the resin solution is subsequently neutralized. The resins thus obtained are used in papermaking as assistants for increasing the dry and wet strength of paper and result in less dulling of the whiteness of the paper.

    6.
    发明专利
    未知

    公开(公告)号：DE59007652D1

    公开(公告)日：1994-12-08

    申请号：DE59007652

    申请日：1990-08-22

    Applicant: BASF AG

    Inventor： FLORY KLAUS ,  STANGE ANDREAS ,  KROENER MICHAEL ,  SENDHOFF NORBERT

    IPC: C08G12/12 ,  C08G12/46 ,  D21H17/49 ,  D21H17/50

    Abstract: Cationic urea/formaldehyde resins are obtainable by condensing urea and formaldehyde in a molar ratio of from 1:1.5 to 1:3 in the presence of polymers which contain not less than 1 mol % of polymerized vinylamine units and have Fikentscher K values of from 5 to 300, in an amount of from 5 to 50 g per mole of urea in the end product, where the mixture is first a) precondensed at a pH of from 8 to 14, then acidified and b) condensed at a pH of from 1 to 5 until gel formation begins, c) then from 0.3 to 1.5 moles of formaldehyde are added per mole of urea used, d) post-condensation is carried out and e) the resin solution is subsequently neutralized. The resins thus obtained are used in papermaking as assistants for increasing the dry and wet strength of paper and result in less dulling of the whiteness of the paper.

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