| 摘要 |
Paper strengthened by starch, typically in amounts of 3 to 15% dry weight, is made by flocculating a cellulosic suspension using a polymeric retention aid which can be dissolved cationic starch but is preferably a synthetic polymer having IV above 4 dl/g, optionally shearing the resultant flocculated suspension and reflocculating it by adding bentonite or other microparticulate anionic material, draining the flocculated or reflocculated suspension and drying the resultant wet sheet, wherein insoluble particles of starch are added to the suspension as a slurry of substantially freely dispersed particles in part or all of the aqueous solution of the polymeric retention aid or in part or all of the aqueous suspension of microparticulate anionic material. In the process improved retention of starch may be obtained when the aqueous solution of the polymeric retention aid also contains a cationic coagulant selected from inorganic cationic coagulants and cationic polymeric materials having intrinsic viscosity 3 dl/g or below and charge density at least 4 meq/g.
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