Gypsum wallboard and method for producing same
AssigneeNational Gypsum Company
InventorArthur E. Kennedy
Life of this patent
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Abstract
A paper-covered gypsum core wallboard made of a cover paper having on the inner surface a synthetic size of the class consisting of certain substituted succinic acid anhydrides, certain substituted glutaric acid anhydrides and the reaction product of maleic anhydride and an internal olefin, which reduces the absorption by the paper of components of the wet gypsum slurry, without affecting substantially the paper porosity, and, of prime importance, without any deleterious effect on the bond of the paper to the gypsum core, either prior to the drying of the board or after the drying of the board.
Claims6
The method of treating paper which comprises completely forming a web of paper by a wet process of forming paper, drying at least partially said web of paper, and coating one surface of said at least partially dried web of paper with a synthetic size, said synthetic size being of the group consisting of (1) a cyclic dicarboxylic acid anhydride corresponding to the structural formula ##STR3## wherein R is selected from the class consisting of dimethylene and trimethylene radicals and wherein R' is a long hydrophobic side chain and is selected from the class of alkyl, alkenyl, aralkyl and aralkenyl groups and (2) the reaction product of maleic acid anhydride and an internal olefin in an amount sufficient to attain in said sheet, at a time subsequent to said coating, a Cobb value of about 0.4 to 1.0 gram as measured on the surface of said sheet which is coated.
Dependencies are inferred from the claim text.