Abstract: An improved sizing is feasible by adding into a papermaking pulp slurry an aqueous dispersion prepared by mixing an aqueous solution of an ampholytic acrylamide polymer having both cationic and anionic groups with a liquid substituted succinic anhydride or with an anhydrous liquid mixture of a liquid substituted succinic anhydride and an oil-in-water type surfactant. Such a paper sizing process is very useful for making plasterboard base paper of multilayered structure composed of at least one surface layer having a high hot water resistance and at least one back layer having a good adhesiveness to plaster slush.

Abstract: A composite paper particularly adapted for use as cover sheets in the production of gypsum wallboard, the paper being sufficiently porous to permit better drainage and more rapid drying in the production of the paper, and when applied to the surfaces of a gypsum slurry for forming wallboard, permits less heat to be utilized in the wallboard conversion, thereby saving energy in the board production required for drying the board. The paper comprises in weight percent:(A) cellulosic fibers in an amount of from about 65% to about 90% and preferably having a fiber freeness of from about 300 ml to about 550 ml Canadian Standard Freeness,(B) calcium sulfate as a filler in an amount of from about 10% to about 35%,(C) a binder in an amount from about 1% to about 31/2%,(D) a flocculant in an amount of from about 0.1% to about 0.2%,(E) a buffering agent in an amount from about 0.

Abstract: A method for producing fire retardant or non-combustible fibrous products. Fibrous organic or inorganic materials, or a mixture thereof, are processed into a slurry, which is then intimately mixed with a boron-containing mineral and a mineral acid. The mixture is allowed to ripen, and is fed into a sheet forming and dewatering apparatus to form a dewatered, fibrous web, which is dried to form the fibrous product.

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.

Abstract: A mineral board product is formed having a low density backing layer and a high density damage-resistant surface layer on conventional fourdrinier equipment in a continuous wet-laid process by initially forming a low density water-laid sheet by flowing a slurry of the board-forming materials onto the wire of a fourdrinier and, at that point on the wire where the mat has formed but at which the water content is between about 7.0 and 12.0 percent, a surfacing layer is applied by means of a secondary head box to the mat, the slurry forming said surfacing layer having a slurry consistency of between about 10 and 15 percent and a Canadian Standard Freeness of between about 150 and 300.

Abstract: Paper and paperboard made of felted cellulose fibers are chemically modified by applying to them an isopropenyl ester containing a catalytic amount of an acid catalyst and then heat curing the treated product. The process imparts water repellancy to the paper products with a very low degree of add-on, but with a very high degree of retention of tensile strength. The products also have excellent printability, are resistant to boiling water, and retain their opacity after exposure to water.

Abstract: A colored decorative plastic laminate is made from a core layer and a superimposed decorative layer comprising: a fibrous material, coloring particles having a Moh's hardness of up to about 6 and an average particle size range of between about 53 to 210 microns, and thermoset resin; where the weight ratio of fiber material:coloring particles is from about 1:0.04 to 1:0.4 and the colored decorative layer is characterized in that the pigments are dispersed only through the bottom two-thirds of the colored layer and concentrated in the colored layer near the core-decorative layer interface, the top one-third of the colored layer containing substantially no pigment particles.

Abstract: A pressure sensitive recording sheet adapted for imaging under the pressure of a typewriter key or other writing instrument. The sheet comprises a ply of high surface area polyolefin fibers masking a colored medium therein. The ply of polyolefin fibers when subjected to the localized pressure of a writing instrument becomes relatively transparent in the region where the pressure is applied, to make distinct the colored medium distributed in the recording sheet.