The invention provides a method for preparing amphiprotic
starch solution for
papermaking, which belongs to the field of fine chemicals for
papermaking. The amphiprotic
starch solution is added at a
papermaking wet end, and has a dry strengthening effect on paper.
Starch is used as the basic material, water,
sodium hydroxide,
sodium hypochlorite or
potassium persulfate and cationic etherifying agent are added. The amphiprotic
starch solution is obtained after the
aqueous solution is heated. The preparation method is fulfilled by the heating reaction of
aqueous solution. The amphiprotic starchsolution has
high concentration, can be diluted by cold water to any concentration and cannot be aged, so the technical problem of starch aging is solved. When in use, the amphiprotic starch solutioncan be added at the wet end without being heated to gelatinize, the amphiprotic
starch solution as dry-strengthening agent for papermaking can notably increase the dry strength indexes of paper, suchas burst index and ring crush index, and under the circumstance of the same added amount, the amphiprotic
starch solution has a better effect than the like product. The innovation of the invention isthat a simple technique for producing the amphiprotic
starch solution is provided, the production time is not longer than 2 hours, the aging and retrograding problems of the amphiprotic starch are solved, and the invented amphiprotic starch solution can be directly added at the papermaking wet end without going through the step of gelatinization by heating.