Dispersing polymers with improved thermal stability
View Patent ↗The invention relates mainly to a polymer comprising a hydrocarbon-based main chain bearing carboxylic groups and polyalkoxylated chains and up to 4% by weight of anti-oxidant groups, relative to the weight of the final polymer, grafted to the main chain. It also relates to a method for preparing such a polymer and to an admixture which is of use as a plasticizer of suspensions of mineral particles comprising same. Finally, it is related to the use of such a polymer for fluidifying suspensions of mineral particles and reducing the water demand of hydraulic compositions.
1. A polymer comprising a main hydrocarbon chain bearing carboxylic groups and polyalkoxylated chains, and comprising 0.01 to 4% by weight, based on the weight of the final polymer, of antioxidant groups grafted to the main chain.
2. The polymer according to claim 1 , comprising between 0.1 and 4% by weight of antioxidant groups, based on the weight of the polymer.
3. The polymer according to claim 1 , wherein the antioxidant groups comprise an aromatic amine.
4. The polymer according to claim 1 , wherein the antioxidant group stems from a compound of the following formula (I):
wherein:
R1 is a hydrogen or a saturated or unsaturated, linear or branched hydrocarbon chain or one or more aromatic optionally fused rings, comprising from 1 to 100 carbon atoms optionally interrupted with one or more heteroatoms;
R2 is identical or different and may independently of each other, be a hydrogen or a saturated or unsaturated, linear or branched hydrocarbon chain, or one or more aromatic optionally fused rings, comprising from 1 to 100 carbon atoms, optionally interrupted with one or more heteroatoms, and/or optionally substituted with one or more amine, alcohol, ketone, halogenated derivative, isocyanate, acetoacetonate, silanol, carboxylic acid and alcohol ester, epoxide, carbonate or mercaptan, phosphate, phosphonate, sulfate, sulfonate or carboxylate groups;
F is an amine group, an alcohol, ketone, halogenated derivative, isocyanate, acetoacetonate, silanol, carboxylic acid and alcohol ester, epoxide, carbonate or mercaptan group bound to the aromatic ring optionally through a saturated or unsaturated, linear or branched hydrocarbon chain comprising up to 100 carbon atoms.
5. The polymer according to claim 4 , wherein said heteroatom is O, S, N or P.
6. The polymer according to claim 4 , wherein R1 is hydrogen.
7. The polymer according to claim 4 , wherein said heteroatom is O, S, N or P.
8. The polymer according to claim 4 , wherein R2 is hydrogen.
9. The polymer according to claim 4 , wherein the amine group is a primary amine group.
10. The polymer according to claim 1 , wherein the antioxidant group is grafted to the main chain via a carboxylic group, by means of an amide or ester bond.
11. The polymer according to claim 1 , wherein the polymer has a weight average molar mass of between 1,000 and 1,000,000 (Mw).
12. The polymer according to claim 1 , as a powder.
13. A method for preparing a polymer according to claim 1 , comprising the step of:
(i) esterifying a polycarboxylic compound with an alkoxy polyalkoxyglycol in the presence of an antioxidant compound, which may react under conditions of the reaction with a reactive function born by the polycarboxylic compound in order to form a covalent bond between the polycarboxylic compound and the antioxidant compound.
14. The method according to claim 13 , wherein the step (i) is carried out in two distinct steps:
(a) the reaction mixture is first brought to a temperature comprised between 50 and 95° C. and under reduced pressure;
(b) the reaction is then continued by heating to a temperature comprised between 100 and 200° C. under reduced pressure and/or under a flow of inert gas until the end of the reaction.
15. The method according to claim 13 , further comprising a step for powdering the obtained grafted polymer.
16. The method according to claim 15 , wherein the powdering step is directly carried out from the polymer stemming from step (b).
17. The method according to claim 15 , wherein the powdering step comprises the steps of:
putting the obtained grafted polymer in an aqueous solution; and
powdering the obtained polymer solution, notably by atomization, flaking through a thin film on a drum or milling.
18. A polymer obtainable by the method according to claim 13 .
19. A method of plasticizing a suspensions of mineral particles comprising adding to said suspension of mineral particles an admixture comprising the polymer according to claim 1 .
20. The method according to claim 19 , wherein the admixture is a limpid aqueous solution.
21. The method according to claim 20 , wherein the admixture comprises from 10 to 50% by weight of the polymer.
22. A method of fluidifying a suspension of particles comprising adding to the suspension of particles a polymer according to claim 1 .
23. A method of reducing water demand of a hydraulic composition comprising adding to said hydraulic composition a polymer according to claim 1 .
24. The method according to claim 23 , wherein the polymer is added in liquid form and/or as a powder before and/or during milling of a cement.
25. The polymer according to claim 1 , wherein the polymer has a weight average molar mass of between 5,000 and 110,000 (Mw).