| 摘要 |
1385809 Water-insoluble acrylamide copolymers AMERICAN CYANAMID CO 22 Dec 1972 [23 Dec 1971] 59546/72 Heading C3P [Also in Division D2] Aqueous latices of water-insoluble polymers comprising at least 60 weight per cent of unsubstituted acrylamide units, at least 5 weight per cent of hydrophobic "vinyl" monomer units, at least 2 weight per cent of N-[di-(C 1-3 alkyl)aminomethyl]acrylamide units and optionally up to 10 weight per cent of anionic monomer units, said polymers being autodispersible in water to form non- creaming dispersions, a 10 weight per cent dispersion at pH 9À5 and 25‹ C. having a viscosity of 250 to 200,000 cps., may be prepared by treating a latex of a copolymer having at least 61À4 weight per cent of unsubstituted acrylamide units with 0À02 to 0À3 mol of formaldehyde per mol of acrylamide units and at least a molar equivalent relative to the formaldehyde of a water-soluble di-(C 1-3 alkyl)amine at 10‹ to 40‹ C. and at an alkaline pH until the polymer particles have become cationic when tested at pH 4À0, or alternatively by direct copolymerization of the substituted acrylamide. The hydrophobic monomer may be styrene, chlorostyrene, chloromethylstyrene, methyl acrylate, methyl methacrylate, propyl acrylate, isobutylene or acrylonitrile; and the anionic units may be introduced by copolymerizing acrylic, methacrylic or maleic acid or by hydrolysing a portion of the acrylamide units. The latices may be added to paper making pulps to give improved dry strength. Examples describe the reaction of latices of acrylamide/styrene copolymers with formaldehyde and (1) dimethylamine and (2) dipropylamine, and the reaction of latices of (3) acrylamide/methyl methacrylate copolymer and (4) acrylamide/acrylonitrile/isobutylene copolymer with formaldehyde and dimethylamine, a small proportion of the acrylamide units being hydrolysed to acrylic acid units. |
