(meth)acrylic comb polymer containing a (meth)acrylic ester as a dispersing and anti-defoaming agent in an aqueous suspension of calcium sulfate hemihydrate
AssigneeCoatex, S. A.
InventorsJean-Marc SUAU, Yves Kensicher
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Abstract
This invention relates to the use, in a foamy aqueous suspension of calcium sulfate hemihydrate, as an agent having the dual function of being a dispersing agent and an anti-defoaming agent, of a comb polymer made up of (meth)acrylic acid, a monomer which is an alcoxy- or hydroxy-polyalkylene glycol, and an ester of (meth)acrylic acid. It also relates to the aqueous suspensions thereby formed, and the plasterboard manufactured from 2 sheets of paper containing a body resulting from the drying of said suspensions.
Claims15
1- A foamy aqueous suspension of calcium sulfate hemihydrate, comprising water, calcium sulfate hemihydrate, and a comb polymer comprising:
- a) (meth)acrylic acid,
- b) an ester of (meth)acrylic acid, and
- c) an alcoxy- or hydroxy-polyalkylene glycol.
2- A foamy aqueous suspension according to claim 1, wherein said comb polymer comprises, expressed as a percentage by weight of the total weight of a), b) and c):
- a) from 5% to 30% of at least one monomer which is (meth)acrylic acid,
- b) from 1% to 20% of at least one monomer which is an ester of (meth)acrylic acid, and
- c) from 70% to 90% of at least one monomer which is an alcoxy- or hydroxy-polyalkylene glycol,
- the sum of percentages a), b) and c) being equal to at least 50% by weight of the total weight of the comb polymer.
3- A foamy aqueous suspension according to claim 1, wherein, for said comb polymer, monomer a) is methacrylic acid.
4- A foamy aqueous suspension according to claim 1, wherein, for said comb polymer, monomer b) is chosen from among ethyl acrylate, butyl acrylate, and methyl methacrylate.
5- A foamy aqueous suspension according to claim 1, wherein, for said comb polymer, monomer c) is a monomer with formula (I):
- R-(A—O)m—(B—O)n—R′ (I)
- m and n are integers less than 150, at least one of which is nonzero,
- A and B designate alkyl groups which are different from one another, and having 2 to 4 carbon atoms,
- R designates a polymerizable unsaturated function,
- R′ represents hydrogen or an alkyl group having 1 to 4 carbon atoms.
6- A plasterboard comprising two sheets of paper and a body therebetween, the body comprising a dried foamy aqueous suspension comprising water, calcium sulfate hemihydrate and at least one comb polymer according to claim 1.
7- A plasterboard according to claim 6, wherein said comb polymer is a comb polymer according to claim 2.
8- A plasterboard according to claim 6, wherein said comb polymer is a comb polymer according to claim 3.
9- A plasterboard according to claim 6, wherein said comb polymer is a comb polymer according to claim 4.
10- A plasterboard according to claim 6, wherein said comb polymer is a comb polymer according to claim 5.
11- A comb polymer comprising:
- a) (meth)acrylic acid,
- b) an ester of (meth)acrylic acid, and
- c) an alcoxy- or hydroxy-polyalkylene glycol.
12- A comb polymer according to claim 11, wherein said comb polymer comprises, expressed as a percentage by weight of the total weight of a), b) and c):
- d) from 5% to 30% of at least one monomer which is (meth)acrylic acid,
- e) from 1% to 20% of at least one monomer which is an ester of (meth)acrylic acid, and
- 0 from 70% to 90% of at least one monomer which is an alcoxy- or hydroxy-polyalkylene glycol,
- the sum of percentages a), b) and c) being equal to at least 50% by weight of the total weight of the comb polymer.
13- A comb polymer according to claim 11, wherein, for said comb polymer, monomer
- a) is methacrylic acid.
14- A comb polymer according to claim 11, wherein, for said comb polymer, monomer
- b) is chosen from among ethyl acrylate, butyl acrylate, and methyl methacrylate.
15- A comb polymer according to claim 11, wherein, for said comb polymer, monomer
- c) is a monomer with formula (I):
- R-(A—O)m—(B—O)n—R′ (I)
- m and n are integers less than 150, at least one of which is nonzero,
- A and B designate alkyl groups which are different from one another, and having 2 to 4 carbon atoms,
- R designates a polymerizable unsaturated function,
- R′ represents hydrogen or an alkyl group having 1 to 4 carbon atoms.