Gypsum composition

Claim 2

A GYPSUM COMPOSITION OBTAINED BY MOLDING AND DRYING AN AQUEOUS SLURRY COMPRISING 100 PARTS BY WEIGHT OF CALCINED GYPSUM, 0.1 TO 50 PARTS BY WEIGHT OF AT LEAST ONE POLYVINYL ALCOHOL HAVING A DEGREE OF SAPONIFICATION OF AT LEAST 50 MOLE PERCENT, 0.1 TO 50 PARTS BY WEIGHT OF AT LEAST ONE THERMOSETTING RESIN, AND 0.001 TO 1 MOLE PER HYDROXYL GROUP IN THE POLYVINYL ALCOHOL OF AT LEAST ONE METL COMPOUND WHICH FORMS A CHELATED BOND WITH THE HYDROXYL GROUP.

Claim 3

A composition according to claim 1, wherein the polyvinyl alcohol is selected from the group consisting of saponification products of polyvinyl formate, acetate or propionate having a degree of saponification of at least 50 mole percent, saponification products of copolymers of vinyl formate, acetate or propionate and a vinylic monomer copolymerizable therewith having a degree of saponification of at least 50 mole percent, acetalized saponification products of polyvinyl formate, acetate or propionate having a degree of saponification of at least 50 mole percent, the degree of acetalization of which is up to 15 mole percent, and graftcopolymers of a vinylic or conjugated diene monomer on saponification products of polyvinyl formate, acetate or propionate having a degree of saponification of at least 50 mole percent, the proportion of the vinylic or conjugated diene monomer being up to 5 moles per one vinyl alcohol unit in the saponification product.

Claim 4

A composition according to claim 2, wherein the copolymers are those of vinyl formate, acetate or propionate and acrylonitrile, acrylic acid, maleic anhydride, methyl methacrylate, 2-hydroxyethyl acrylate, or glycidyl methacrylate, and the graft copolymers are those of acrylonitrile, acrylic acid, methyl methacrylate, 2-hydroxyethyl acrylate, glycidyl methacrylate, or chloroprene on the saponification product of polyvinyl formate, acetate or propionate.

Claim 5

A composition according to claim 1, wherein the amount of the metal compound is 0.004 to 0.1 mole per one hydroxyl group in the polyvinyl alcohol.

Claim 6

A composition according to claim 1, wherein the amount of the thermosetting resin is 0.5 to 20 parts by weight per 100 parts by weight of the calcined gypsum.

Claim 7

A composition according to claim 1, wherein the amount of water in the aqueous slurry is 50 to 120 parts by weight per 100 parts by weight of the calcined gypsum.

Claim 8

A composition according to claim 1, wherein the thermosetting resin is selected from a condensation product of melamine and formaldehyde, a condensation product of a urea and formaldehyde, a condensation product of a phenol and formaldehyde, and a condensation product of a guanamine and formaldehyde, and derivatives thereof.

Claim 9

A composition according to claim 1, wherein the metal compound is selected from the group consisting of compounds of metals of Groups Ib, II, IIIa, IV, Vb, VIb, VIIb and VIII of the Periodic Table.

Claim 10

A composition according to claim 8, wherein the metal is selected from the group consisting of copper, calcium, magnesium, zinc, aluminum, silicon, tin, titanium, zirconium, vanadium, chromium, molybdenum, manganese, iron, and nickel.

Claim 11

A composition according to claim 8, wherein the metal is selected from the group consisting of calcium, magnesium, aluminum, silicon, tin and titanium.

Claim 12

A composition according to claim 8, wherein the metal compound is selected from the group consisting of a sulfate, nitrate, carbonate, acetate, halide, hydroxide and oxide.

Claim 13

A composition according to claim 1, wherein the metal compound is selected from the group consisting of copper acetate, copper nitrate, copper sulfate, copper bromide, copper iodide, magnesium iodide, calcium acetate, strontium nitrate, barium oxide, zinc acetate, zinc chloride, cadmium fluoride, mercuric acetate, aluminum chloride, aluminum sulfate, silicon oxide, stannous chloride, stannic chloride, stannous sulfate, lead acetate, titanium sulfate, titanium hydroxide, zirconium oxychloride, vanadium trichloride, vanadium pentoxide, niobium chloride, chromous chloride, potassium dichromate, molybdenum oxide, tungstic acid, manganese chloride, manganese dioxide, manganese acetate, ferrous chloride, ferric chloride, ferric nitrate, cobaltous sulfate, cobalt acetate, nickel chloride, and nickel acetate.

Claim 14

A composition according to claim 1, wherein the metal compound is selected from the group consisting of calcium acetate, magnesium iodide, aluminum chloride, aluminum sulfate, silicon oxide, stannous chloride, stannic chloride and titanium sulfate.

Claim 15

A composition according to claim 1, wherein the aqueous slurry contains an acid or an amine.

Claim 16

A composition according to claim 14, wherein the acid or amine is hydrogen halide, sulfuric acid, nitric acid, formic acid, chloroacetic acid, benzenesulfonic acid, p-toluenesulfonic acid, ammonia, pyridine, pyrrole, triethylenediamine, dimethylamine or diethylamine.

Claim 17

A composition according to claim 1, wherein the aqueous slurry contains a synthetic fiber, natural fiber, cellulose, or an inorganic fiber.

Claim 18

A composition according to claim 1, wherein the amount of the fiber is 0.5 to 10 parts by weight per 100 parts by weight of the calcined gypsum.

Claim 19

A composition according to claim 1, wherein the aqueous slurry contains a density-reducing material selected from the foameD polystyrene beads, ''''Shirasu'''' balloon, perlite and wood flour in a proportion of 0.5 to 200 parts by weight per 100 parts by weight of the calcined gypsum.

Claim 20

A composition according to claim 1, wherein the aqueous slurry contains a filler selected from ''''Shirasu,'''' powdered glass, clay and powdered polyvinyl alcohol in a proportion of 0.5 to 200 parts by weight per 100 parts by weight of the calcined gypsum.

Claim 21

A composition according to claim 1, wherein the aqueous slurry contains at least one polymer latex selected from SBR latex, NBR latex, natural rubber latex, polyvinyl acetate latex, ethylene-vinyl acetate copolymer latex, polyvinyl chloride latex, polystyrene latex, and their carboxyl-containing polymer latexes, in a proportion of 0.1 to 50 parts by weight per 100 parts by weight of the calcined gypsum.