A Comparison of the Methods Used to Produce Water-Resistant Starch Coatings

Part I Literature Survey The use of the starch in the coating of paper has been very extensive. The reason being that starch and its conversion products have most of the desirable characteristics of a coating adhesive and are relatively inexpensive. Only one main characteristic is missing in coatings made with starch and that is the lack of water resistance. For many years the paper industry, the adhesive industry, and the textile industry have searched for a method of modifying starch so as to increase its water resistance. A great many processes have developed from these studies. These processes consist of blocking the hydroxyl group of the starch by the use of cross linkage or by the use of a protective water resistant substance either over or mixed through the starch. This is achieved by the use of antimony salts (8, 12, 13), urea formaldehyde resins (6, 7, 9, 12, 15, 21, 22, 29, 33), formaldehyde (23, 24, 2, 27), melamino formaldehyde resins (10, 28, 34), phenol formaldehyde resins (25), chronic salts (4, 5, 16, 17, 18), silicates (1), estor gum emulsion (11), polyvinyl alcohols (30, 31), nitro cellulose (3), latices (32), and various synthetic resins (26). These methods vary in ease of application and results accomplished. There are many other methods of water proofing starch but most of them are not applicable to starch coatings