Aqueous dispersion of hydrosoluble or hydroswellable polymer

Abstract

The present invention concerns an aqueous dispersion comprising particles of water-soluble polymer of average molecular weight higher than or equal to 0.5 million daltons, or of water-swellable polymer, and a mixture of at least one sulfate salt and at least one phosphate salt in weight proportions of between 25:75 and 75:25.

Claims

1. An aqueous dispersion comprising particles of a water-soluble polymer of average molecular weight greater than or equal to 0.5 million daltons, or of a water-swellable polymer, and a mixture of at least one sulfate salt and at least one phosphate salt in weight proportions of between 25:75 and 75:25, the water-soluble or water-swellable polymer being a homopolymer of acrylamide or methacrylamide, or of a copolymer of acrylamide or methacrylamide and of an anionic monomer selected from the group consisting of acrylic acid, methacrylic acid, 2-acrylamido-2-methylpropane sulfonic acid and the salts thereof, or of a copolymer of acrylamide or methacrylamide and of a cationic monomer selected from the group consisting of quaternized dialkylaminoethyl acrylate (DAMEA), quaternized dialkylaminoethyl methacrylate (DAMEMA), diallyldimethylammonium chloride (DADMAC), acrylamido propyltrimethylammonium chloride (APTAC), and methacrylamido propyltrimethylammonium chloride (MAPTAC), wherein the mixture of at least one sulfate salt and at least one phosphate salt is a mixture of ammonium sulfate and diammonium phosphate; and wherein the phosphate salt is not a polyphosphate salt.

2. The aqueous dispersion according to claim 1, wherein it comprises between 5 and 60 weight % of the particles of water-soluble or water-swellable polymer.

3. The aqueous dispersion according to claim 1, wherein it comprises between 10 and 40 weight % of the mixture of at least one sulfate salt and at least one phosphate salt.

4. The aqueous dispersion according to claim 1, wherein the aqueous dispersion comprises the mixture of at least one sulfate salt and at least one phosphate salt in weight proportions of between 65:35 and 35:65.

5. The aqueous dispersion according to claim 1, wherein the water-soluble polymer has an average molecular weight of between 0.5 and 40 million daltons.

6. The aqueous dispersion according to claim 1, wherein the polymer particles have a mean diameter ranging from 0.1 to 1000 μm.

7. The aqueous dispersion according to claim 1, wherein said aqueous dispersion comprises a dispersive organic polymer selected from among polymers of molecular weight ranging from 500 to 100 000 daltons.

8. The aqueous dispersion according to claim 7, wherein it comprises less than 30 weight % of the dispersive organic polymer.

9. A method comprising using the aqueous dispersion according to claim 1 for a use selected from the group consisting of in the petroleum and gas industry, hydraulic fractionation, paper production processes, water treatment, sludge dewatering, building industry, mining industry, cosmetics, agriculture, textile industry, and detergents.

Description

EXAMPLES

Example 1: Static, Suspensive, Stability at 20° C., of Aqueous Dispersions of Water-Swellable Acrylamide Homopolymers Containing Different AMS (Ammonium Sulfate)/DAP (Diammonium Phosphate) Ratios

(1) 350 g of aqueous polymer dispersion previously prepared via dispersion polymerization (weight concentration of polymer: 22%, and of AMS or AMS/DAP mixture: 25%) were placed in a glass tube (diameter: 50 mm, height: 300 mm). After one year, the height of the destabilised phase (creaming or sedimentation) was evaluated as a percentage in relation to the total initial height of aqueous dispersion.

(2) TABLE-US-00001 TABLE 1 Aqueous AMS/DAP dispersion weight ratio Stability A 100:0  Sedimentation 50% B 40:60 Creaming 35% C 50:50 Stable  0% D 60:40 Sedimentation 31%

(3) The aqueous dispersion of water-swellable polymer is stable when prepared in a 50:50 AMS/DAP mixture. Stability remains reasonable for preparations in AMS/DAP mixtures of 60:40 or 40:60. The aqueous dispersion in unstable when prepared solely in the presence of AMS.

(4) When compositions B and D are mixed after the stability study, the compositions become stable. Sedimentation is therefore reversible.

Example 2: Static, Suspensive Stability at 50° C., of Aqueous Dispersions of Polyacrylamides

(5) The following dispersions were prepared via aqueous solution polymerization.

(6) Aqueous dispersion C: 22 weight % of water-swellable acrylamide homopolymer (Example 1), 25 weight % of AMS/DAP mixture (50:50 weight ratio).

(7) Aqueous dispersion E: 22 weight % of water-soluble copolymer of acrylamide and sodium acrylate (70:30, mol %) of average molecular weight 15 million daltons, 20 weight of AMS.

(8) Stability of dispersions C and E after 2 months was evaluated with the same method as in Example 1, at a temperature of 50° C.

(9) TABLE-US-00002 TABLE 2 Aqueous dispersion Stability C Stable 0.1% E Sedimentn.  50%

(10) For this study on accelerated stability (50° C., 2 months), an aqueous polymer dispersion in an AMS/DAP mixture of 50:50 weight ratio is more stable than a dispersion only containing AMS.

(11) When composition E is mixed after the stability study, the composition does not become stable. Sedimentation is not reversible.

Example 3: Limit Incorporation Threshold of Active Material in an Aqueous Dispersion of Water-Swellable Acrylamide Homopolymers

(12) For following cases 1 and 2, the dispersions were prepared by aqueous dispersion polymerization. For each case, solely the weight concentration of polymer was changed. All the dispersions contained 25 weight % of salt (AMS or AMS/DAP mixture).

(13) For each dispersion, Brookfield viscosity (model LV3 or LV4, 30 rpm-1, 25° C.) was measured and filterability was determined by passing the dispersion through a 300 μm filter.

(14) Case 1: Aqueous Dispersions of Water-Swellable Polymer Containing AMS

(15) TABLE-US-00003 TABLE 3 Brookfield Weight concentration viscosity of polymer (%) (cps) Filterability 22 800 Filterable 25 4300 Non-filterable 26.5 5000 Non-filterable
Case 2: Aqueous Dispersions of Water-Swellable Polymer Containing AMS/DAP (Weight Ratio 50:50).

(16) TABLE-US-00004 TABLE 4 Brookfield Weight concentration viscosity of polymer (%) (cps) Filterability 22 500 Filterable 25 800 Filterable 26.5 1400 Filterable

(17) Comparison of the results in Tables 3 and 4 evidences that a suitable AMS/DAP mixture allows a limited increase in viscosity and prevents agglomeration of the polymer particles (agglomeration makes dispersions non-filterable at 300 μm, gelling phenomenon) when the weight concentration of polymer is increased.

Example 4: Formulation and Evaluation of the Stability of an Aqueous Dispersion of Water-Soluble Polymer

(18) This example concerns the formulation of aqueous dispersions of water-soluble polymer P1 via dispersion of solid particles of said polymer in an aqueous solution. The final weight concentration of polymer is 10%.

(19) a) Formulation of Dispersions of Water-Soluble Polymer

(20) The water-soluble polymer P1 is a copolymer of acrylamide having overall cationicity of 10 mol %. The copolymer before formulation of the dispersion is in the physical form of a powder having a particle size of between 5 μm and 300 μm and dry matter of 90%.

(21) Formulations of aqueous dispersions of polymer P1:

(22) TABLE-US-00005 TABLE 5 Quantity (weight %) Ingredient Dispersion F Dispersion G Water 47.58 47.59 Ammonium sulfate (AMS) 23.59 39.31 Diammonium phosphate (DAP) 15.73 0.00 Attagel 50 (BASF) 2.00 2.00 Polymer P1 11.10 11.10 Total 100.00 100.00 AMS/DAP ratio 60:40 100:0 P1 Concentration (weight %) 10.0 10.0

(23) b) Evaluation of the Dynamic Stability of Aqueous Dispersions of Water-Soluble Polymer.

(24) Dynamic stability was characterized by measuring the sedimentation rate.

(25) The apparatus used was the LUMiSizer by LUM. LUMiSizer is an analytical centrifuge which, in accelerated fashion, is able to determine the stability of polymer dispersions. By means of a very high-performance optical system, the LUMiSizer can analyse heights or rates of sedimentation and/or creaming of solid polymer particles. Height is expressed in mm whilst rate is expressed in mm/month. The higher this value the lesser the stability of the dispersion.

(26) TABLE-US-00006 TABLE 6 Sedimentation rate Dispersion (mm/month) F Invention 19 G Reference 31

(27) This example shows that aqueous polymer dispersion F containing 10 weight % of cationic polymer and formulated with the AMS/DAP mixture (60:40) is more stable that dispersion G formulated solely with AMS.

Example 5: Formulation and Evaluation of the Stability of an Aqueous Dispersion of Water-Soluble Polymer

(28) This example concerns the formulation of aqueous dispersions of water-soluble polymer P1 by dispersing solid particles of said polymer in an aqueous solution. The final weight concentration of polymer was 20%.

(29) a) Formulation of Dispersions of Water-Soluble Polymer

(30) TABLE-US-00007 TABLE 7 Quantity (weight %) Ingredient Dispersion H Dispersion I Water 40.82 40.82 Ammonium sulfate (AMS) 20.99 34.98 Diammonium phosphate (DAP) 13.99 0.00 Attagel 50 (BASF) 2.00 2.00 Polymer P1 22.20 22.20 Total 100.00 100.00 AMS/DAP ratio 60:40 100:0 P1 concentration (weight %) 20.0 20.0

(31) b) Evaluation of the Dynamic Stability of Aqueous Dispersions of Water-Soluble Polymer.

(32) Dynamic stability was characterized by measuring the sedimentation rate (as in Example 4).

(33) TABLE-US-00008 TABLE 8 Sedimentation rate Dispersion (mm/month) H Invention 14 I Reference 27

(34) This new example shows that the aqueous dispersion of polymer H containing 20 weight % of cationic polymer and formulated with the AMS/DAP mixture (weight ratio: 40:60) is again more stable than dispersion I formulated solely with AMS.