Dry strength, paper

Solarek D, Tessler MM, Jobe P, Peek L. Cationic Starch Aldehydes - Wet End Additives for Temporary Wet Strength and Improved Dry Strength. Paper Chemistry Symposium Stockholm, Sweden STFI and SPCI organizers 1988 Sept. 27-290... 

Papermaking additives can be categorized either as process additives or as functional additives. Process additives are materials that improve the operation of the paper machine, such as retention and drainage aids, biocides, dispersants, and defoamers they are primarily added at the wet end of the paper machine. Functional additives are materials that enhance or alter specific properties of the paper product, such as fillers (qv), sizing agents, dyes, optical brighteners, and wet- and dry-strength additives they may be added internally or to the surface of the sheet. 

Amino resins are used by the paper industry in large volume for a variety of apphcations. The resins are divided into two classes according to the mode of appHcation. Resins added to the fiber slurry before the sheet is formed are called wet-end additives and are used to improve wet and dry strength and stiffness. Resins appHed to the surface of formed paper or board, almost invariably together with other additives, are used to improve the water resistance of coatings, the sag resistance in ceiling tiles, and the scuff resistance in cartons and labels. 

This reduces pulp tensile strength but improves tear strength not because of fiber degradation but because the hemiceUuloses bond chemically to give added tensile strength in the final paper product. To overcome this loss in hemiceUulose polymers, starch is added on the wet end of the paper machine as a dry strength additive. 

Recycled paper contains more fines, short fibers, and anionic trash. This will increase demand for process chemicals such as drainage aids and both wet- and dry-strength additives (43). 

One of the difficulties of using starch as a surface size is that when surface-sized papers are recycled, the starch is readily solubilised into the aqueous system where it contributes to the nutritional pollution load of the effluent. This can be controlled to a large extent by introducing cationic groups into the starch molecule which bind strongly to the anionic cellulose in a similar manner to starches used as dry strength agents (Chapter 7). 

Starches - [FILLERS] (Vol 10) - [FOODS, NONCONVENTIONAL] (Vol 11) -dry-strength additives [PAPERMAKING ADDITIVES] (Vol 18) -as food additives [FOOD ADDITIVES] (Vol 11) -mpotash flotation [POTASSIUMCOMPOUNDS] (Vol 19) -for printing papers [PRINTING PROCESSES] (Vol 20)... 

Paper and textile production retention, coagulation, flocculation, wet strength, dry strength improvement, dewatering, color fastness, dye fixation, antistatic agents, antimicrobial treatment... 

Cationic oat starch was used to improve the dry strength of paper handsheets and found to be comparable to wheat starch in functionality.14 Oat starch might possibly be a replacement for rice starch in pharmaceutical applications.19 Oat flour has been used in adhesive preparations.19... 

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