Patent ID: 7687560
Filing Date: 2010-03-30
Classification: B32B,C08F,C08J,C08K,Y10T

Abstract:
1. A process for preparing a low color, polyvinyl butyral sheet for use in the manufacture of glass laminates comprising the steps: (I) admixing polyvinyl alcohol, butyraldehyde, an acid or mixture of acids, water, and sodium dialkyl sulfosuccinate; (II) stabilizing the mixture obtained in step (I) by (a) raising the pH of the mixture to at least pH 10, (b) isolating the polyvinyl butyral resin composition by draining the liquid, and (c) washing the polyvinyl butyral resin composition with neutral pH water; (III) plasticizing the polyvinyl butyral resin composition with from about 30 to about 50 pph of plasticizer selected from the group consisting of triethylene glycol di(2-ethylhexanoate), tetraethylene glycol diheptanoate, dibutyl sebacate, and mixtures thereof, based on the dry weight of the 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 polyvinyl butyral resin composition; and (V) extruding the polyvinyl butyral resin composition at a temperature of from about 175° C. to about 225° C. to obtain a polyvinyl butyral sheet having a glass transition temperature (T