Gypsum-based composite materials reinforced by cellulose ethers
AssigneeInnovative Construction and Building Materials
InventorsJacob Freas Pollock, Christopher D. Tagge, Lennard Torres, David S. Soane
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Abstract
A gypsum-based composite structure is prepared from a slurry comprising a mixture of calcium sulfate hemihydrate, a cellulose ether additive other than CMC and an amount of water that is sufficient to form a slurry. The calcium sulfate hemihydrate is hydrated by the water forming a wallboard core reinforced by the cellulose ether additive. The concentration, viscosity grade and degree of substitution of the cellulose ether are selected to give the composite improved nail pull resistance and greater flexural strength.
Claims62
A composite structure comprising:
- gypsum;
- and
- an additive, wherein the gypsum forms by hydration of a calcium sulfate hemihydrate in the presence of the additive and water, and the additive is of a cellulose ether other than CMC, and both a viscosity grade of the cellulose ether and a degree of substitution of at least one substitutional group of the cellulose ether are selected such that the strength of the composite is substantially increased compared to a structure prepared without the additive.
A process for making a composite structure comprising:
- mixing together a calcium sulfate hemihydrate powder and a powdered additive, until the powdered additive is dispersed throughout the calcium sulfate hemihydrate powder to form a mixture;
- combining the mixture and an amount of water forming a slurry;
- shaping the composite structure;
- and
- drying the composite structure, wherein the powdered additive is a cellulose ether having at least one substitutional group selected from the substitutional groups of methyl, hydroxypropyl and hydroxyethyl and the degree of substitution of the at least one substitutional group is selected to be in a range that at least partially immobilizes the additive during drying, preventing migration of the cellulose ether from the interior to the surface of the composite structure.
A process for making a composite structure comprising:
- preparing a mixture comprised of a calcium sulfate hemihydrate, an additive and water;
- wherein the additive is a cellulose ether selected to have both a viscosity grade of at least 100 cps and a degree of substitution of at least one substitutional group selected from one of a methyl group, an hydroxypropyl group and an hydroxyethyl group such that the composite structure has a substantially increased strength compared to a structure made without the additive;
- and forming the composite structure from the mixture.
A composite structure comprising:
- gypsum;
- an additive;
- and
- a reinforcement, wherein the gypsum forms by hydration of a calcium sulfate hemihydrate in the presence of the additive, the reinforcement, and water, and the additive is of a cellulose ether, and the reinforcement is surface modified, by a surface modifier whereby the strength of the composite structure is substantially increased compared to a structure prepared without the additive and the reinforcement.
Dependencies are inferred from the claim text.