Gypsum plaster

• US 20040258901A1
• Filed: 04/14/2004
• Published: 12/23/2004
• Est. Priority Date: 04/20/1998
• Status: Abandoned Application

• Current Assignee: Bpb Placo (Compagnie De Saint-Gobain)
• Original Assignee: Bpb Placo (Compagnie De Saint-Gobain)
• Inventors: Mayer, Peter, Davies, Jason, Luckevich, Lydia
• Application Number:
  US10/823,783
• Publication Number:
  US 20040258901A1
• Time in Patent Office: Days
• US Class Current: 428/297.1
• CPC Class Codes: C04B 14/02 Granular materials , e.g. microballoons
• CPC Class Codes: C04B 14/104 Bentonite, e.g. montmorillonite
• CPC Class Codes: C04B 16/0633 Polypropylene
• CPC Class Codes: C04B 18/082 Cenospheres
• CPC Class Codes: C04B 2103/0079 Rheology influencing agents
• CPC Class Codes: C04B 2111/00129 Extrudable mixtures
• CPC Class Codes: C04B 2111/00137 Injection moldable mixtures
• CPC Class Codes: C04B 2111/00301 Non-porous materials, e.g. macro-defect free [MDF] products
• CPC Class Codes: C04B 24/2623 Polyvinylalcohols; Polyvinylacetates
• CPC Class Codes: C04B 24/32 Polyethers, e.g. alkylphenol polyglycolether
• CPC Class Codes: C04B 24/383 Cellulose or derivatives thereof
• CPC Class Codes: C04B 28/146 alpha-hemihydrate
• CPC Class Codes: C04B 40/0089 making use of vacuum or reduced pressure
• CPC Class Codes: Y02W 30/91 Use of waste materials as fillers for mortars or concrete
• CPC Class Codes: Y10T 428/249939 Two or more layers

Abstract

An extrudable gypsum plaster paste is disclosed comprising: α gypsum plaster, water in a substantially stoichiometric amount; a binder; and a clay or another rheology modifier functionally equivalent to a clay. Such pastes can have a yield stress sufficient to make the paste self supporting. The invention also provides a method for making an extrudable gypsum plaster paste comprising: mixing α gypsum plaster, water in a substantially stoichiometric amount and a binder; and mixing into that mixture a clay or other rheology modifier functionally equivalent to a clay.

Claims

1. An extruded, stamped, pressed, rolled or injection molded gypsum plaster product made from a paste comprising:

α

gypsum plaster;

water in an amount of from 70% to 170% of the stoichiometric amount;

a binder; and

a clay or another rheology modifier functionally equivalent to a clay,

the product being substantially free of macro defects.

4. A product according to claim 1 in which the rheology modifier is present in the said paste in an amount of up to 20% weight of plaster.

5. A product according to claim 1 in which all the gypsum plaster is α

gypsum plaster.

6. A product according to claim 1 in which the water is present in the said paste in an amount of from 13% to 32% by weight of plaster.

7. A product according to claim 1 in which the binder is a cellulosic binder.

8. A product according to claim 1 in which the binder is at least one of polyvinylalcohol and polyethyleneglycol.

9. A product according to claim 1 in which the binder is present in an amount of at least 0.1% by weight.

10. A product according to claim 1 in which the binder is present in an amount of no more than 10% by weight.

11. The product according to claim 1, further comprising a component selected from the group consisting of setting retarder, lightweight aggregate and fiber.

12. A product according to claim 11 in which the lightweight aggregate is ceramic microspheres or cenospheres.

13. A product according to claim 11 in which the lightweight aggregate is present in an amount of up to 20% by weight.

14. A product according to claim 11 in which the fiber is glass or polypropylene fiber.

15. A product according to claim 11 in which the fiber is present in an amount of up to 10% by weight.

16. The product according to claim 11, in which the water is present in said paste in an amount of from 13% to 32% by weight of a plaster.

17. A method for making a gypsum plaster product according to claim 1 comprising forming a paste by:

mixing α

gypsum plaster, water in an amount of from 70% to 170% of the stoichiometric amount and a binder;

mixing into that mixture a clay or other rheology modifier functionally equivalent to a clay;

working the paste into a plastic condition; and

extruding, stamping, pressing or injection molding the paste to form a shaped product.

20. A method according to claim 17, further comprising forming a pre-gel/suspension comprising water and binder and adding α

gypsum plaster to the pre-gel/suspension.

21. A method according to claim 17 further comprising adding a setting retarder to the composition.

22. A method according to claim 17 carried out at a temperature above 60°

C.

23. A method according to claim 17 in which the paste is extruded after working and in which the extruded paste is supported as it leaves the die.

26. A product according to claim 1 in which the binder is present in an amount of at least 1% by weight.

27. A product according to claim 1 in which the binder is present in an amount of no more than 5% by weight.

31. A product according to claim 4 in which the binder is at least one of polyvinylalcohol and polyethyleneglycol.

32. A product according to claim 5 in which the binder is at least one of polyvinylalcohol and polyethyleneglycol.

33. A product according to claim 6 in which the binder is at least one of polyvinylalcohol and polyethyleneglycol.

34. A product according to claim 7 in which the binder is at least one of polyvinylalcohol and polyethyleneglycol.

2. An extruded, stamped, pressed, rolled or injection molded gypsum plaster product made from a paste comprising:

α

gypsum plaster;

water in an amount of from 70% to 170% of the stoichiometric amount,

a binder; and

a rheology modifier such that the paste has a yield stress sufficient to make the paste self supporting,

the product being substantially free of macro defects.

3. A product according to claim 2 in which the rheology modifier is a clay.

18. A method for making a gypsum plaster product according to claim 2 comprising forming a paste by:

mixing α

gypsum plaster, water in an amount of from 70% to 170% of the stoichiometric amount and a binder;

mixing into that mixture a rheology modifier such that the paste has a yield stress sufficient to make the paste self supporting;

working the paste into a plastic condition; and

extruding, stamping, pressing or injection molding the paste to form a shaped product.

19. A method according to claim 18 in which a clay is mixed into the said mixture as the rheology modifier.

29. A product according to claim 2 in which the binder is at least one of polyvinylalcohol and polyethyleneglycol.

30. A product according to claim 3 in which the binder is at least one of polyvinylalcohol and polyethyleneglycol.

35. A method according to claim 18 in which the paste is extruded after working and in which the extruded paste is supported as it leaves the die.

24. A gypsum plaster paste comprising:

α

gypsum plaster;

water in an amount of from 70% to 170% of the stoichiometric amount;

a binder; and

a rheology modifier such that the paste has a yield stress sufficient to make the paste self supporting,

the product being substantially free of macro defects.

25. A paste according to claim 24 in which the rheology modifier is a clay.

28. An extruded, stamped, pressed, rolled or injection molded gypsum plaster product made from a paste comprising:

α

gypsum plaster;

water in an amount of from 70% to 170% of the stoichiometric amount;

a binder; and

a clay or another rheology modifier functionally equivalent to a clay,

the product being substantially free of macro defects wherein said paste is made by

mixing α

gypsum plaster, water in an amount of from 70% to 170% of the stoichiometric amount and a binder;

mixing into that mixture a rheology modifier such that the paste has a yield stress sufficient to make the paste self supporting;

working the paste into a plastic condition; and

extruding, stamping, pressing or injection molding the paste to form a shaped product.