Patent ID: 7642307
Filing Date: 2010-01-05
Classification: B32B,C08K,Y10T

Abstract:
1. A process for preparing a low color poly(vinyl butyral) sheet comprising the steps: (I) admixing polyvinyl alcohol, butyraldehyde, an acid or mixture of acids, water, and sodium dioctyl sulfosuccinate to form a mixture, (II) stabilizing the mixture obtained in step (I) by (a) raising the pH of the mixture to at least pH 10, (b) isolating polyvinyl butyral resin by draining liquid, (c) washing the poly(vinyl butyral) resin with neutral pH water; (III) plasticizing the polyvinyl butyral resin with a finite amount of less than 30 pph of plasticizer based on the dry weight of the poly(vinyl butyral) resin; (IV) mixing (a) a polyvinyl butyral bleaching compound selected from the group consisting of organic bisulfites, inorganic bisulfites and sulfosuccinates and, optionally, (b) an antioxidant and a UV light stabilizer, with the poly(vinyl butyral) resin; and (V) extruding the polyvinyl butyral after completion of steps (III) and (IV) at a temperature of from about 225° C. to about 245° C. to obtain the polyvinyl butyral sheet, the polyvinyl butyral sheet having a T