Paper sizing with aq. soln. of anionic size and cationic starch - forming stable mixt., giving better results than anionic or neutral starch

摘要

Paper sizing process employs an aq. soln. of a water-soluble salt of an anionic synthetic size (I) and a starch, which contains 0.5-8, pref. 1-6 wt.% cationically modified starch (II). (I) is a copolymer of ethylenically unsatd., nonionic monomers (e.g. 2-24C olefins, esp. diisobutylene, styrene and derivs., vinyl ethers, esters, amides and imides of 3-6C ethylenically unsatd. mono- or di-carboxylic acids) with 40-95 wt.% anionic monomers (e.g. 3-6C ethylenically unsatd. acids, anhydrides and hemi-esters). (II) are prim., sec., tert. or quat. amino-starch derivs., other cationic modified N-substd. starch derivs. or cationic sulphonium or phosphonium starch derivs. The soln. contains 0.3-5, pref. 1-2% (I). (I) and (II) can be combined without pptn. and the mixts. are stable and can be processed on the sizing press without difficulty. The results are superior to those obtd. with (I) and anionic or neutral starches. It is also possible to carry out neutral sizing in the absence of alum and/or Na aluminate.