Absorbent modified starch ether(s) - contg. water-insoluble fraction, prepd. by reaction with hydroxy reactive crosslinking agent

摘要

Starch ethers which after etherification alone would be mainly water soluble, are modified by reaction in a wet alkaline medium with a cross linking reagent (I) to give 40 wt.% water-insoluble, absorbent modified starch ethers. The modification is carried out e.g. with 0.005-0.2 pts. of a reactant contg. =1 OH-reactive functional gp. chosen from (a) acrylamido gp. H2C=C(R1)-CO-N (where R1 = H or CH3); (b) alpha-halo epoxy gp. (where Hal = Cl or Br); (c) chlorazomethine gp. -N=C(Cl)-; (d) allyloxyazomethine gp. -N=C-O-C-H2-CH=CH2 or (e) phosphorus oxychloride. The modification can also be carried out with 0.01-0.3 pts.wt. per pt.wt. starch of a reagent H2C=C(R1)-CO-N(R3)(R2) (II) or H2C=CH-SO2-N(R4)(R5) (III) in which R1 = H or CH3, R2 = H and R3 = CH3, CH2OH, 1-3C N-methyleneacylamido, 2-7C esterified N-methylenecarboxyamido- or N-carboxymethylenecarbamido gp.; or R2 and R3 = CH3 or CH2OH and R4 and R5 = H or R4=H and R5=CH3 or R4 and R5 = CH3. Pref. the etherification and/or the modification are carried out in the presence of 0.2 pts.wt. of a 1-6C alcohol per pt.wt. starch. The process gives modified starch ethers with improved absorbency, and uses smaller amts. of organic solvent than previous processes. The prods. are useful e.g. in the prepn. of absorbent materials, urine, blood, sweat, saliva, etc., and esp. sanitary towels.