Desoto, Inc.

Charles W Strobel

Fred D Hawker

Laura M Wells

Maryam L Dachniwskyj

Thomas H Plaisance

John E Katchko

A thermosetting size applyable to paper in a size press and curable at a temperature not in excess of about 280.degree. F. for 10 seconds is disclosed. This size comprises an aqueous emulsion comprising water having suspended therein aqueous emulsion copolymer particles of monoethylenically unsaturated monomers comprising hydroxy-functional monomer having an hydroxy number of at least about 20, and the balance of the monomers provides a water insoluble polymer having a glass transition temperature of from about -20.degree. C. to about 50.degree. C. The emulsion has a pH greater than about 2.5, preferably from 4.0 to 7.0, and a stoichiometric deficiency of an aminoplast cross-linking agent is used for cure. An acid curing catalyst is uniformly distributed in the size to speed the cure.

Thermosetting size press composition

A process for drying a water-wet paste containing polymeric beads without agglomeration is disclosed in which there is added to the wet paste a proportion of an organic solvent which forms an azeotrope with water, such as methyl isobutyl ketone, in an amount providing a stirrable mixture, and the solvent-containing aqueous paste is heated to remove the water as an azeotrope with the solvent and to produce a water free suspension of the beads in organic solvent. The proportion of azeotropic solvent can be minimized by adding a resinous vehicle in organic solvent solution to the solvent-containing aqueous paste after substantially all the water has been removed, and continuing the application of heat to remove undesired organic solvent and thereby increase the solids content. As a feature of the invention, a pigment which is incompatible with the azeotropic solvent, such as an aqueous dispersion of lamp black, is added to the aqueous paste either before or after the addition of azeotropic organic solvent to be present while the water is azeotropically removed to avoid flooding.

Growing community of inventors

Schaumburg, IL, United States of America

Charles W Strobel