Gypsum set accelerator and method of preparing same

Patent metadata

Field	Value
Publication number	US-2018305257-A1
Application number	US-201815918449-A
Country	US
Kind code	A1
Filing date	Mar 12, 2018
Priority date	Apr 20, 2017
Publication date	Oct 25, 2018
Grant date	—

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

1 . A gypsum set accelerator comprising dry loose finely ground 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, phosphate salt, and/or pregelatinized starch,
wherein the calcium sulfate dihydrate was co-ground with the grinding aid, wherein the phosphate salt comprises trimetaphosphate salt, tripolyphosphate salt, and/or tetra-pyrophosphate salt.

2 . The gypsum set accelerator of claim 1 , wherein the grinding aid comprises beta-naphthalene sulfonate formaldehyde condensate calcium salt, beta-naphthalene sulfonate formaldehyde condensate sodium salt, sodium trimetaphosphate, potassium trimetaphosphate, calcium trimetaphosphate, sodium calcium trimetaphosphate, lithium trimetaphosphate, ammonium trimetaphosphate, sodium tripolyphosphate, potassium tripolyphosphate, tetrasodium pyrophosphate, tetrapotassium pyrophosphate, and/or pregelatinized starch.

3 . The gypsum set accelerator of claim 1 , wherein the grinding aid comprises beta-naphthalene sulfonate formaldehyde condensate calcium salt, beta-naphthalene sulfonate formaldehyde condensate sodium salt, and/or sodium trimetaphosphate.

4 . The gypsum set accelerator of claim 1 , wherein the grinding aid comprises beta-naphthalene sulfonate formaldehyde condensate sodium salt and/or beta-naphthalene sulfonate formaldehyde condensate calcium salt.

5 . The gypsum set accelerator of claim 1 , wherein the grinding aid comprises beta-naphthalene sulfonate formaldehyde condensate sodium salt and/or beta-naphthalene sulfonate formaldehyde condensate calcium salt, and wherein the grinding aid further comprises sodium trimetaphosphate.

6 . The gypsum set accelerator of claim 1 , wherein the grinding aid comprises sodium trimetaphosphate, sodium tripolyphosphate, potassium tripolyphosphate, tetrasodium pyrophosphate, and/or tetrapotassium pyrophosphate.

7 . 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; 1-10 parts by weight said phosphate salt per 100 parts by weight calcium sulfate dihydrate; and 1-60 parts by weight said pregelatinized starch per 100 parts by weight calcium sulfate dihydrate.

8 . 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; 3-8 parts by weight said phosphate salt per 100 parts by weight calcium sulfate dihydrate; and/or 5-40 parts by weight said pregelatinized starch per 100 parts by weight calcium sulfate dihydrate.

9 . The gypsum set accelerator of claim 1 , wherein the grinding aid comprises the pregelatinized starch, optionally sodium trimetaphosphate, optionally non-pregelatinized starch, and optionally dextrose.

10 . The gypsum set accelerator of claim 1 , wherein the grinding aid comprises the pregelatinized starch, optionally sodium trimetaphosphate, optionally non-pregelatinized starch, and optionally dextrose, wherein the pregelatinized starch is an amount of up to about 40% by weight based on the weight of the calcium sulfate dihydrate.

11 . The gypsum set accelerator of claim 9 , wherein the grinding aid comprises less than 0.1 wt. % dextrose based on the weight of the dry calcium sulfate dihydrate.

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

13 . 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, phosphate salt, and/or pregelatinized starch, and
optionally dextrose and/or non-pregelatinized starch.

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

15 . The method of claim 14 , wherein the grinding aid comprises beta-naphthalene sulfonate formaldehyde condensate sodium salt and sodium trimetaphosphate.

16 . The method of claim 14 , wherein the grinding aid comprises pregelatinized starch, optionally with sodium trimetaphosphate.

17 . The method of claim 14 , wherein the co-grinding is performed by ball milling.

18 . 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.

19 . The method of claim 18 , 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; 3-8 parts by weight said phosphate salt per 100 parts by weight calcium sulfate dihydrate; and/or 5-40 parts by weight said pregelatinized starch per 100 parts by weight calcium sulfate dihydrate.

20 . The method of claim 18 ,
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

• C04B18/24

  Vegetable refuse, e.g. rice husks, maize-ear refuse; Cellulosic materials, e.g. paper {, cork} · CPC title

• C04B22/16

  containing phosphorus in the anion, e.g. phosphates · CPC title

• C04B24/383

  Cellulose or derivatives thereof · CPC title

• C04B28/14

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

• C04B2103/12

  Set accelerators · CPC title