Gypsum set accelerator and method of preparing same

Patent metadata

Field	Value
Publication number	US-10737979-B2
Application number	US-201815918449-A
Country	US
Kind code	B2
Filing date	Mar 12, 2018
Priority date	Apr 20, 2017
Publication date	Aug 11, 2020
Grant date	Aug 11, 2020

Abstract

A modified gypsum set accelerator and a method of preparing the same is provided, which includes dry loose finely ground particles of a mixture of ground dry calcium sulfate dihydrate and a grinding aid selected from one or more of beta-naphthalene sulfonate formaldehyde condensate, trimetaphosphate phosphate salt, tripolyphosphate salt, tetra-pyrophosphate salt, and pregelatinized starch.

First claim

What is claimed is:

1. A gypsum set accelerator comprising dry loose finely around particles, comprising a mixture of
dry solid particles of ground dry calcium sulfate dihydrate and a grinding aid comprising dry solid particles of beta-naphthalene sulfonate formaldehyde condensate sodium salt and/or beta-naphthalene sulfonate formaldehyde condensate calcium salt, and the grinding aid comprises dry solid particles of sodium trimetaphosphate,
wherein the calcium sulfate dihydrate was co-ground with the grinding aid.

2. The gypsum set accelerator of claim 1 , wherein the gypsum set accelerator comprises one or more of:
1-10 parts by weight said beta-naphthalene sulfonate formaldehyde condensate per 100 parts by weight calcium sulfate dihydrate; and
1-10 parts by weight said sodium trimetaphosphate per 100 parts by weight calcium sulfate dihydrate.

3. The gypsum set accelerator of claim 1 , wherein the gypsum set accelerator comprises:
2-8 parts by weight said beta-naphthalene sulfonate formaldehyde condensate per 100 parts by weight calcium sulfate dihydrate; and/or
3-8 parts by weight said sodium trimetaphosphate per 100 parts by weight calcium sulfate dihydrate.

4. The gypsum set accelerator of claim 1 , wherein the grinding aid further comprises pregelatinized starch.

5. The gypsum set accelerator of claim 1 , wherein the grinding aid further comprises a pregelatinized starch, wherein the pregelatinized starch is an amount of up to about 40% by weight based on the weight of the calcium sulfate dihydrate.

6. The gypsum set accelerator of claim 4 , wherein the grinding aid comprises less than 0.1 wt. % dextrose based on the weight of the dry calcium sulfate dihydrate.

7. The gypsum set accelerator of claim 1 , wherein the gypsum set accelerator has an absence of calcium sulfate hemihydrate.

8. The gypsum set accelerator of claim 1 , consisting of:
the calcium sulfate dihydrate,
the grinding aid consisting of:
the dry solid particles of beta-naphthalene sulfonate formaldehyde condensate and the dry solid particles of trimetaphosphate salt, and
optionally dextrose and/or optionally non-pregelatinized starch.

9. A method of preparing the gypsum set accelerator of claim 1 , comprising co-grinding dry the calcium sulfate dihydrate with the grinding aid.

10. The method of claim 9 ,
wherein the grinding aid comprises the beta-naphthalene sulfonate formaldehyde condensate sodium salt and the sodium trimetaphosphate.

11. The method of claim 9 , wherein the grinding aid further comprises pregelatinized starch.

12. The method of claim 9 , wherein the co-grinding is performed by ball milling.

13. A method, comprising:
mixing water, calcium sulfate hemihydrate, and the gypsum set accelerator of claim 1 to make an aqueous slurry; and
depositing the aqueous slurry on a paper sheet and allowing the aqueous slurry to set to obtain a gypsum board.

14. The method of claim 13 , wherein the gypsum set accelerator comprises:
2-8 parts by weight said Beta-naphthalene sulfonate formaldehyde condensate per 100 parts by weight calcium sulfate dihydrate; and/or
3-8 parts by weight said sodium trimetaphosphate per 100 parts by weight calcium sulfate dihydrate.

15. The method of claim 13 ,
wherein the water, the calcium sulphate hemihydrate, the gypsum set accelerator, and a cellulosic fiber are mixed to form the aqueous slurry, and
further comprising depositing the aqueous slurry on a paper sheet and allowing the slurry to set to obtain a fiberboard.

Assignees

• United States Gypsum Co

Inventors

• Lu Runhai
• Sang Yijun
• Song Weixin D

Classifications

• C04B28/145 Primary

  Calcium sulfate hemi-hydrate with a specific crystal form · CPC title

• C04B2103/52

  Grinding aids; Additives added during grinding · CPC title

• C04B40/0042

  Powdery mixtures · CPC title

• C04B20/026

  Comminuting, e.g. by grinding or breaking; Defibrillating fibres other than asbestos · CPC title

• C04B2111/0062

  Gypsum-paper board like materials · CPC title