Calcium sulphase-based products

Patent metadata

Field	Value
Publication number	US-11117834-B2
Application number	US-201515524956-A
Country	US
Kind code	B2
Filing date	Nov 17, 2015
Priority date	Nov 21, 2014
Publication date	Sep 14, 2021
Grant date	Sep 14, 2021

Abstract

A calcium sulphate-based product including gypsum and a shrinkage resistance additive. The shrinkage resistance additive is a metal nitrate, hydroxide, acetate or sulphate and is preferably provided in an amount greater than 4 wt % (based on the amount of additive and gypsum). The additive may be a nitrate of an alkali metal (e.g. potassium), an alkaline earth metal (e.g. magnesium or calcium), a transition metal (e.g. iron or zinc) or aluminium.

First claim

The invention claimed is:

1. A calcium sulphate-based product comprising:
gypsum, and
a shrinkage resistance additive provided in an amount between 4 wt % and 40 wt % based on a weight of the gypsum and the shrinkage resistance additive, wherein
the shrinkage resistance additive is an acetate of magnesium, an acetate of zinc, or an acetate of iron.

2. The product according to claim 1 , wherein the product is a building material or a mould for metal casting.

3. The product according to claim 1 , wherein the product is a composite wallboard comprising a core of the gypsum and shrinkage resistance additive sandwiched between two liners.

4. A calcium sulphate-based product prepared by a process comprising the steps of:
providing calcined gypsum,
providing a shrinkage resistance additive in an amount between 4.5 wt % and 50 wt % based on a weight of the gypsum and the shrinkage resistance additive, and
drying an aqueous slurry comprising the calcined gypsum and the shrinkage resistance additive, wherein
the shrinkage resistance additive is an acetate of magnesium, an acetate of zinc, or an acetate of iron.

5. A calcium sulphate-based composition for use in forming a calcium sulphate-based product by drying an aqueous slurry of the calcium sulphate-based composition, the calcium sulphate-based composition comprising:
calcined gypsum, and
between 4.5 wt % and 50 wt % of a shrinkage resistance additive based on an amount of the gypsum and the shrinkage resistance additive, wherein
the shrinkage resistance additive is an acetate of magnesium, an acetate of zinc, or an acetate of iron.

6. A method of forming a calcium sulphate-based product by drying an aqueous slurry comprising a composition according to claim 5 .

7. The method according to claim 6 , wherein the product is a building material or a mould for casting metal.

8. The method according to claim 7 , wherein the product is a composite wallboard and the method comprises drying the aqueous slurry between two liners.

Assignees

• Saint Gobain Placo

Inventors

• Brooks Laura
• Fisher Robin
• Rideout Jan

Classifications

• C04B2111/00939

  for the fabrication of moulds or cores · CPC title

• C04B22/085

  containing nitrogen in the anion, e.g. nitrites · CPC title

• C04B2111/00612

  as one or more layers of a layered structure · CPC title

• C04B28/14 Primary

  containing calcium sulfate cements {(gypsum-paper plates E04C)} · CPC title

• C04B2103/58

  Shrinkage reducing agents · CPC title