Carboxylated-carboxylic polyglycerol compositions for use in cementitious compositions
View Patent ↗The invention relates to compositions and methods for modifying cementitious materials such as by reducing setting time. Polymer compositions of the invention are derived by polyetherifying mono-glycerols, optionally with alkylene glycols, to obtain polyglycerol homopolymers or copolymers, and then carboxylating the obtained polyglycerol homopolymers and/or copolymers with an organic acid having at least two carboxylic functionalities. The set retardation effect of the carboxylated-carboxylic polyglycerol polymer compositions in cementitious materials is reduced is compared to polyglycerol polymer not having the carboxylated-carboxylic groups, while its water reducing ability is maintained without loss of early compressive strength. Cementitious compositions and methods involving the carboxylated-carboxylic polyglycerol are also covered by the invention.
1. A cementitious composition, comprising: a hydratable cementitious binder and a carboxylated-carboxylic polyglycerol polymer having a number average molecular weight of 800 to 20,000, the carboxylated-carboxylic polyglycerol polymer being formed by
(a) providing mono-glycerols having hydroxide groups capable of forming ether linkages;
(b) forming ether linkages from and between some of said mono-glycerol hydroxide groups, to obtain polyglycerol homopolymers;
(c) carboxylating said obtained polyglycerol homopolymers with at least one or both of the following polycarboxylic acid compounds represented by the following structures
or R 1 O(O)C—Y—C(O)OR 2
wherein
X and Y each independently represent C 1 -C 10 saturated or unsaturated aliphatic or aromatic groups, said groups optionally containing a nitrogen atom or one or more carboxylic or sulfonic groups; and
R 1 and R 2 each independently represent hydrogen or C 1 -C 3 alkyl groups.
2. The cementitious composition of claim 1 wherein, in said step (b), said forming of ether linkages is carried out at 200° C. -300° C.
3. The cementitious composition of claim 1 wherein, in said step (b), said forming of ether linkages is carried out in the presence of a catalyst.
4. The cementitious composition of claim 3 wherein, in said step (b), said forming of ether linkages is carried out in the presence of a catalyst selected from sodium carbonate, sodium hydroxide, or mixture thereof.
5. The cementitious composition of claim 1 wherein, in said step (c), said polycarboxylic acid compound is aliphatic or aromatic and contains at least two carboxylic groups in the form of a free acid, anhydride, or carboxylate ester.
6. The cementitious composition of claim 5 wherein, in said step (c), said polycarboxylic acid is an acid anhydride.
7. The cementitious composition of claim 6 wherein said X represents a group selected from —CH 2 —CH 2 — group of succinic anhydride, —CH 2 —CH 2 —CH 2 — group of glutaric anhydride, and —CH=CH— group of maleic anhydride.
8. The cementitious composition of claim 1 wherein, in said step (c), said forming of ether linkages is carried out at 70° C. -150° C. for 1-10 hours.
9. The cementitious composition of claim 1 wherein the weight ratio of polyglycerol to acid is 10/90 to 90/10.
10. The cementitious composition of claim 1 wherein the weight ratio of polyglycerol to acid is 25/75 to 75/25.
11. A method for making the cementitious composition of claim 1 comprising introducing to said hydratable cementitious composition said carboxylated-carboxylic polyglycerol in the amount of 0.05% to 2.0% by weight of cement.
12. The method of claim 11 wherein the amount of said carboxylated-carboxylic polyglycerol is 0.08% to 1.0% by weight of cement.
13. The method of claim 12 wherein the amount of said carboxylated-carboxylic polyglycerol is 0.12% to 0.6% by weight of cement.
14. The cementitious composition of claim 1 further comprising at least one other agent selected from the group consisting of a water-reducing agent, an alkanolamine, a defoamer, an air-entraining agent, or mixtures thereof.
15. The cementitious composition of claim 14 wherein said at least one other agent is a water-reducing agent selected from a gluconate, lignosulfonate, naphthalene sulfonate, melamine sulfonate, or polycarboxylate superplasticizer.
16. A cementitious composition, comprising: a hydratable cementitious binder and a carboxylated-carboxylic polyglycerol polymer having a number average molecular weight of 800 to 20,000, the carboxylated-carboxylic polyglycerol polymer being formed by
(a) providing mono-glycerols having hydroxide groups capable of forming ether linkages;
(b) forming ether linkages from and between some of said mono-glycerol hydroxide groups to obtain polyglycerol homopolymers;
(c) carboxylating said obtained polyglycerol homopolymers with at least one or both of the following polycarboxylic acid compounds represented by the following structures
or R 1 O(O)C—Y—C(O)OR 2
wherein
X independently represents a —CH=CH— group of maleic anhydride and Y independently represents a C 1 -C 10 saturated or unsaturated aliphatic or aromatic groups, and Y optionally contains a nitrogen atom or one or more carboxylic or sulfonic groups; and
R 1 and R 2 each independently represent hydrogen or C 1 -C 3 alkyl groups.