Compositions and methods for water-resistant gypsum fiber products

Patent metadata

Field	Value
Publication number	US-9410058-B2
Application number	US-201514604960-A
Country	US
Kind code	B2
Filing date	Jan 26, 2015
Priority date	Apr 10, 2014
Publication date	Aug 9, 2016
Grant date	Aug 9, 2016

Abstract

A water-resistant gypsum fiber product comprising siloxane and coated with a coating comprising alkali metal organosiliconate is provided. A method of making a gypsum fiber product in which siloxane is cross-linked at the surface of the product is also provided. A fuel-efficient method for making the product and reducing the amount of siloxane dust released is provided as well.

First claim

What is claimed is:

1. A method for decreasing the amount of siloxane dust generated in a kiln, the method comprising:
preparing a gypsum slurry comprising calcium sulfate dihydrate;
heating the slurry under pressure to calcine the calcium sulfate dihydrate to form alpha-calcined calcium sulfate hemihydrate;
relieving the pressure;
after the step of calcining under pressure has been completed and the pressure has been relieved, adding a siloxane dispersion to the slurry;
dewatering the slurry to form a filter cake;
forming the cake into a desired shape;
allowing the cake to set to form a product;
coating the product with a coating comprising alkali metal organosiliconate;
placing the coated product in the kiln; and
thereby decreasing the amount of siloxane dust generated in a kiln.

2. The method of claim 1 , wherein the alkali metal organosiliconate is potassium methyl siliconate.

3. The method of claim 1 , wherein the siloxane is methylhydrogensiloxane.

4. The method of claim 1 , wherein the siloxane is used in amounts of about 0.08% to about 1.0% by weight of the total amount of gypsum.

5. The method of claim 1 , wherein the alkali metal organosiliconate is used in the amount from 0.1% to 10% by weight of the coating and from 0.002% to 2% by weight of the total amount of gypsum.

Assignees

• United States Gypsum Co

Inventors

• Blackburn David R
• Xu Yufeng

Classifications

• C04B2111/00629

  the covering sheets being made of material other than paper · CPC title

• C04B41/009

  characterised by the material treated · CPC title

• C09D183/04 Primary

  Polysiloxanes · CPC title

• C08K2003/3045

  Sulfates · CPC title

• C04B41/4927

  Alkali metal or ammonium salts · CPC title