Anionic (Oxidized) Starch

(Phosphorylated and Carboxyalkylated Starch)

Properties and Applications

Oxidized starch (oxidized amylopectin) can be prepared by treating an aqueous starch slurry or semi-dry starch paste with an oxidizing agent such as hydrogen peroxide, ammonium persulfate, or sodium hypochlorite under alkaline conditions and at ambient or slightly elevated temperature. This process yields highly carboxylated starch. Under the right conditions, it is also possible to selectively oxidize hydroxymethyl groups to carboxyl groups.¹ Another commercially important form of anionic starch is phosphorylated starch which is one of the most common forms of anionic starch. It is prepared by treating starch with sodium tripolyphosphate (STPP) or sodium trimetaphosphate (STMP).²

Oxidized (anionic) starches degrade much faster than conventional starch, i.e. they have improved biodegradability. This type of starch, however, is used on a much smaller scale than cationic starch but it is still an important starch-based additive. Anionic starches are or can be used as a rheology modifiers, thickening agents, flocculants, emulsion stabilizers, textile sizing agents, paper binders and coating agents. When used as coating agents, they improve strength and printing properties and when used as binders they help to bind particles together and on the base paper material.¹

Manufacturers & Distributors

References: ¹International Patent WO 99/23240; ²U.S. Patent 5,855,946 & 6,299,907