# US 9,751,805 B2 · Method for stabilizing beta-hemihydrate plaster > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,751,805 B2 - Document ID: US9751805B2 - Status: Granted - Kind: B2 - Application number: 14/405,155 - Filed: 2013-06-05 - Published: 2015-06-04 - Granted: 2017-09-05 - Earliest claimed: 2012-06-06 - Assignees: Etex Building Performance GmbH - Applicants: Siniat International SAS - Inventors: Winfried Aschern; Jörg Bold - Web page: https://patentgrep.com/patent/US9751805B2 ## CPC - C04B 28/147: {beta-hemihydrate} - C04B 11/007: {After-treatment of the dehydration products, e.g. aging, stabilisation} - C04B 2111/0062: {Gypsum-paper board like materials} - C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE ## Abstract The instant invention is concerned with the post-treatment of β-hemihydrate plasters for the purpose of stabilization. The invention relies in the addition of a retardant to the calcined β-hemihydrate. It is also the purpose of the invention to provide stabilized β-hemihydrate plasters which exhibit advantageous properties. ## Claims ### Claim 1 A process for the manufacture of stabilized β-hemihydrate plaster powder comprising the moistening of calcined β-Hemihydrate with the addition of a retardant. ### Claim 2 (depends on 1) The process according to claim 1, comprising the steps of providing calcined β-hemihydrate plaster; and moistening of said calcined β-Hemihydrate by the addition of water and a retardant to provide stabilized -hemihydrate plaster powder, the amount of moistening water is comprised between 1 and 6% by weight based on the weight of the fed-hemihydrate plaster. ### Claim 3 (depends on 1) The process according to claim 1, wherein the retardant is added together with the moistening water. ### Claim 4 (depends on 1) The process according to claim 1, wherein the amount of residual water in the stabilized β-hemihydrate plaster powder is less than 3.5%, by weight pursuant to standard ASTM C471 M. ### Claim 5 (depends on 1) The process according to claim 1, wherein the amount of residual water in the stabilized 13 -hemihydrate plaster powder is less than 2.6%, by weight pursuant to standard ASTM C471 M. ### Claim 6 (depends on 1) The process according to claim 1, wherein the amount of residual water in the stabilized β-hemihydrate plaster powder is less than 2.2%, by weight pursuant to standard ASTM C471 M. ### Claim 7 (depends on 1) The process according to claim 1, wherein the amount of residual water in the stabilized β-hemihydrate plaster powder is less than 1.8%, by weight pursuant to standard ASTM C471 M. ### Claim 8 (depends on 1) The process according to claim 1, wherein the amount of water is comprised between 1 and 6% by weight based on the weight of the fed β-hemihydrate plaster. ### Claim 9 (depends on 1) The process according to claim 1, wherein the amount of water is comprised between 3 and 5% by weight based on the weight of the fed β-hemihydrate plaster. ### Claim 10 (depends on 1) The process according to claim 1, wherein the amount of retardant is from 0.001 to 0.1% by weight based on the weight of the fed β-hemihydrate plaster. ### Claim 11 (depends on 1) The process according to claim 1, wherein the amount of retardant is from 0.005 to 0.1% by weight based on the weight of the fed β-hemihydrate plaster. ### Claim 12 (depends on 1) The process according to claim 1, wherein the amount of retardant is from 0.01 to 0.03% by weight based on the weight of the fed β-hemihydrate plaster. ### Claim 13 (depends on 1) The process according to claim 1, wherein the retardant is selected from the group consisting of nucleation retardants, hydrolysed or degraded proteins, hydrolysed amino acid, polycondensated amino acid, phosphonic acids and salts thereof, polyphosphoric acid, phosphates and salts thereof, carboxylic acids in basic pH, polyacrylic acids having a molecular weight of less than 5000, and mixtures thereof. ### Claim 14 (depends on 1) The process according to claim 1, wherein the retardant is a hydrolysed amino acid or a mixture thereof. ### Claim 15 (depends on 14) The process according to claim 14, wherein the hydrolysed amino acid is selected from the group consisting of polycondensated amino acid, Ca-salt, polycondensated amino acid Ca-salt as a liquid solution, degraded mixture of polyamides, salified with calcium, modified amino acid or mixture thereof. ### Claim 16 (depends on 1) The process according to claim 1, wherein the β-hemihydrate plaster fed into the process has a temperature comprised between 10° C. and 99° C. ### Claim 17 (depends on 1) The process according to claim 1, wherein the β-hemihydrate plaster fed into the process has a temperature comprised between 25° C. and 80° C. ### Claim 18 (depends on 1) The process according to claim 1, wherein the β-hemihydrate plaster fed into the process has a temperature comprised between 25° C. and 60° C. ### Claim 19 (depends on 1) The process according to claim 1, carried out at atmospheric pressure. ### Claim 20 (depends on 1) The process according to claim 1 wherein the stabilized β-hemihydrate plaster is further subjected to a drying and/or grinding step and optionally stored for at least several days before being subjected to a drying and/or grinding step. ### Claim 21 (depends on 20) The process according to claim 20, wherein the drying step is performed at a temperature within the range of 75 and 130° C. ### Claim 22 (depends on 20) The process according to claim 20, wherein the drying step is performed at a temperature within the range of 75 to 115° C. ### Claim 23 (depends on 20) The process according to claim 20, wherein the drying step is performed at a temperature within the range of 75 to 105° C.