METHOD FOR PREPARING THREE-DIMENSIONAL PLASTER OBJECTS

• US 20110024028A1
• Filed: 07/31/2009
• Published: 02/03/2011
• Est. Priority Date: 07/31/2009
• Status: Active Grant

• Current Assignee: United States Gypsum Company (GEBR Knauf Verwaltungsgesellschaft KG)
• Original Assignee: United States Gypsum Company (GEBR Knauf Verwaltungsgesellschaft KG)
• Inventors: YEUNG, Lee Kon, IMMORDINO, Salvatore C.
• Granted Patent: US 8,323,429 B2
• Time in Patent Office: Days
• US Class Current: 156/244.11
• CPC Class Codes: C04B 2103/44 Thickening, gelling or viscosity increasing agents
• CPC Class Codes: C04B 2103/46 Water-loss or fluid-loss reducers, hygroscopic or hydrophilic agents, water retention agents
• CPC Class Codes: C04B 2103/67 Biocides
• CPC Class Codes: C04B 2103/69 Fungicides
• CPC Class Codes: C04B 2111/00181 Mixtures specially adapted for three-dimensional printing (3DP), stereo-lithography or prototyping
• CPC Class Codes: C04B 28/145 Calcium sulfate hemi-hydrate with a specific crystal form
• CPC Class Codes: C04B 40/0658 Retarder inhibited mortars activated by the addition of accelerators or retarder-neutralising agents

Abstract

The present invention relates to a method for producing three-dimensional plaster objects via thin layer deposition. The inventive method comprises steps of depositing a layer of a calcium sulfate hemihydrate slurry onto the surface of a support in a predetermined pattern and activating the slurry with an activating agent so as to accelerate the setting reaction of calcium sulfate hemihydrate and water to form set calcium sulfate dihydrate. The depositing and activating steps can be repeated as necessary until the desired three-dimensional plaster object is formed.

Claims

1. A method for producing a three-dimensional plaster object, the method comprising:

(a) depositing a first layer of a calcium sulfate hemihydrate slurry onto the surface of a support substrate in a predetermined pattern,

(b) activating the first layer of the calcium sulfate hemihydrate slurry with at least one first activating agent,

(c) depositing a second layer of the calcium sulfate hemihydrate slurry onto the surface of the activated calcium sulfate hemihydrate slurry of step (b) in a predetermined pattern,

(d) activating the second layer of the calcium sulfate hemihydrate slurry with at least one second activating agent, wherein the first and second activating agents can be the same or different,

(e) optionally repeating steps (c) and (d) one or more times to form one or more additional layers until the desired three-dimensional plaster object is formed, and

(f) optionally removing the three-dimensional plaster object from the support substrate,

wherein the activating agent is present in an amount sufficient to accelerate the setting reaction of calcium sulfate hemihydrate and water to form set calcium dihydrate.

2. The method of claim 1, wherein the depositing steps (a) and (c) comprise a manual deposition process, an extrusion deposition process, a controlled spraying deposition process, or a combination thereof.

3. The method of claim 2, wherein the extrusion deposition process is a thin film extrusion process.

4. The method of claim 2, wherein the controlled spraying deposition process is a print head spraying process or a spray head spraying process.

5. The method of claim 4, wherein the spray head spraying process is driven by air pressure, slurry pressure, or a combination thereof.

6. The method of claim 1, wherein the one or more layers of calcium sulfate hemihydrate slurry are deposited in a thickness of about 0.01 mm to about 5.0 mm, and wherein the layers can have the same or different thickness.

7. The method of claim 6, wherein the layers of calcium sulfate hemihydrate slurry are deposited in a thickness of about 0.10 mm to about 1.0 mm.

8. The method of claim 1, wherein the calcium sulfate hemihydrate slurry for each layer can be the same or different and comprises calcium sulfate hemihydrate particles and water.

9. The method of claim 8, wherein the calcium sulfate hemihydrate slurry comprises about 40 to about 80 weight-percent of the calcium sulfate hemihydrate particles.

10. The method of claim 8, wherein the calcium sulfate hemihydrate slurry further comprises a binder, a flow modifier, a water retainer, a rheology modifier, an anti-sedimentation additive, a biocide, a fungicide, or combinations thereof.

11. The method of claim 8, wherein the calcium sulfate hemihydrate slurry further comprises a calcium sulfate hemihydrate set inhibitor, wherein the calcium sulfate hemihydrate set inhibitor is present in an amount sufficient to deactivate the setting reaction of calcium sulfate hemihydrate and water to form set calcium sulfate dihydrate.

12. The method of claim 11, wherein the calcium sulfate hemihydrate slurry further comprises a binder, a flow modifier, a water retainer, a rheology modifier, an anti-sedimentation additive, a biocide, a fungicide, or combinations thereof.

13. The method of claim 11, wherein the calcium sulfate hemihydrate set inhibitor is present in an amount of about 0.01 to about 2.00 weight-percent.

14. The method of claim 11, wherein the calcium sulfate hemihydrate set inhibitor is selected from a group consisting of low molecular weight polymers or copolymers of vinyl acrylates, vinyl acetates, vinyl chlorides, ethylene, styrene, substituted ethylene, and substituted styrene, and polyphosphonic compounds, and combinations thereof.

15. The method of claim 14, wherein the calcium sulfate hemihydrate set inhibitor is a polyphosphonic compound selected from a group consisting of tetrasodiumpyrophosphate, tetrapotassiumpyrophosphate, hexamethylene diamine tetra(methylene phosphonic acid), and combinations thereof.

16. The method of claim 1, wherein the first activating agent and the second activating agent are aqueous solutions or slurries comprising at least one salt, wherein the cation of the at least one salt is selected from a group consisting of aluminum, zinc, iron, an alkali metal, and an alkaline earth metal.

17. The method of claim 16, wherein the anion of the at least one salt is sulfate or chloride.

18. The method of claim 17, wherein the at least one salt is selected from a group consisting of aluminum sulfate, zinc sulfate, sodium sulfate, potassium sulfate, and calcium sulfate.

19. The method of claim 1, wherein the depositing step and activating step for each successive layer of the calcium sulfate hemihydrate slurry are conducted sequentially.

20. The method of claim 1, wherein the depositing step and activating step for each successive layer of the calcium sulfate hemihydrate slurry are conducted concurrently.