Method for modifying the properties of an aqueous suspension

Abstract

A method for modifying the properties of a suspension of solid or liquid particles in an aqueous medium, includes the step of adding to the suspension or to the aqueous medium a polymer prepared by inverse emulsion polymerization of monomers A.sub.b, comprising a betaine group, and of nonionic monomers B.sub.a included in an aqueous phase dispersed in the form of droplets in a hydrophobic external phase, wherein the molar ratio of the monomers A.sub.b to the monomers B.sub.a is from about 4/96 to about 40/60, the polymer exhibits an intrinsic viscosity of greater than 600 mL/g, the reduced specific viscosity being measured by dissolving the polymer in a 20% by weight aqueous NaCl solution.

Claims

1. A method for modifying the properties of a composition of a suspension of dispersed solid or liquid particles in an aqueous medium, comprising adding a polymer to the composition, increasing the viscosity of the composition and promoting the suspending of the dispersed solid or liquid particles in the aqueous medium, wherein said polymer is prepared by inverse emulsion polymerization of monomers A.sub.b, comprising a betaine group, and of nonionic monomers B.sub.a included in an aqueous phase dispersed in the form of droplets in a hydrophobic external phase, wherein the molar ratio of the monomers A.sub.b to the monomers B.sub.a is from about 4/96 to about 40/60, the polymer exhibits an intrinsic viscosity of greater than 600 milliLiters/gram, the intrinsic viscosity being measured by dissolving the polymer in a 20% by weight aqueous NaCl solution, wherein the composition exhibits an ionic strength of at least 0.7 mol/l, and wherein the dispersed particles comprise solid particles comprising sand, density-modifying particles, excavation products, debris, or polymeric particles, and/or liquid particles comprising synthetic oils, oils of vegetable origin, or oils of mineral origin, wherein the composition of the suspension of dispersed solid or liquid particles in the aqueous medium is at a temperature of greater than or equal to 70 C. wherein the suspension comprises greater than or equal to 0.5% of the polymer; and wherein the aqueous medium is a saline composition that comprises at least 35 g/l of a salt.

2. The method according to claim 1, wherein the monomer A.sub.b comprises one or more monomers selected from: alkylsulphonates or -phosphonates of dialkylammonioalkyl acrylates or methacrylates, -acrylamides or -methacrylamides, heterocyclic betaine monomers, alkylsulphonates or -phosphonates of dialkylammonioalkylallylics, alkylsulphonates or -phosphonates of dialkylammonioalkylstyrenes, betaines resulting from ethylenically unsaturated anhydrides and dienes, and phosphobetaines.

3. The method according to claim 1, wherein the monomer A.sub.b comprises one or more monomers selected from sulphohydroxypropyldiethylammonioethyl methacrylate, sulphobetaines derived from piperazine, 2-vinyl-1-(3-sulphopropyl)pyridinium betaine (2SPV or SPV), 4-vinyl-1-(3-sulphopropyl)pyridinium betaine (4SPV), 1-vinyl-3-(3-sulphopropyl)imidazolium betaine, sulphopropylmethyldiallylammonium betaine, alkylsulphonates or phosphonates of dialkylammonioalkylstyrenes, betaines derived from ethylenically unsaturated anhydrides and dienes, and phosphobetaines.

4. The method according to claim 1, wherein the monomer A.sub.b comprises one or more monomers selected from monomers according to the formula: ##STR00021## or the formula: ##STR00022## in which: R.sup.1 is hydrogen or methyl, R.sup.2 and R.sup.3, which are identical or different, are hydrogen or alkyl having from 1 to 6 carbon atoms, Y.sub.1 is a divalent group of formula O or NR.sub.2, Z.sup.is SO.sub.3.sup., m is 2 or 3, and n is 1-6.

5. The method according claim 1, wherein the monomer A.sub.b comprises one or more monomers selected from: sulphopropyldimethylammonioethyl methacrylate (SPE), sulphoethyldimethylammonioethyl methacrylate, sulphobutyldimethylammonioethyl methacrylate, sulphohydroxypropyldimethylammonioethyl methacrylate (SHPE), sulphopropyldimethylammoniopropylacrylamide, sulphopropyldimethylammoniopropylmethacrylamide (SPP), sulphohydroxypropyldimethylammoniopropylmethacrylamide (SHPP), sulphopropyldiethylammonioethyl methacrylate, 2-vinyl-1-(3-sulphopropyl)pyridinium betaine, 4-vinyl-1-(3-sulphopropyl)pyridinium betaine, sulphopropyldimethylammonioethyl methacrylate, 1-vinyl-3-(3-sulphopropyl)imidazolium betaine, and sulphopropylmethyldiallylammonium betaine.

6. The method according to claim 1, wherein the monomer A.sub.b comprises one or more monomers according to the following formulae: ##STR00023##

7. The method according to claim 1, wherein, during the polymerization, the monomer B.sub.a is a hydrophilic monomer included in the disperse aqueous phase.

8. The method according to claim 1, wherein the nonionic monomer B.sub.a comprises one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, glycerol monomethacrylate, acrylamide (AM), methacrylamide, N-methylolacrylamide, dimethylacrylamide, dimethylmethacrylamide, poly(ethylene and/or propylene oxide), if appropriate random or in the block form, -methacrylates, vinyl alcohol or vinylpyrrolidone.

9. The method according to claim 1, wherein the hydrophilic nonionic monomer B.sub.a comprises acrylamide (AM).

10. The method according to claim 1, wherein the monomer A.sub.b is sulphopropyldimethylammonioethyl methacrylate (SPE) or sulphopropyldimethylammoniopropylmethacrylamide (SPP).

11. The method according to claim 1, wherein the hydrophobic external phase is based on a hydrocarbon.

12. The method according to claim 1, wherein the polymerization comprises the following stages: a1): preparation of the inverse emulsion, and a2): polymerization.

13. The method according to claim 12, wherein stage a1) is carried out by emulsification of a mixture comprising the aqueous phase comprising the monomers, the external phase and at least one emulsifying agent.

14. The method according to claim 12, wherein polymerization is carried out by bringing together monomers A.sub.b and optionally monomers B.sub.a with a compound which generates free radicals.

15. The method according to claim 12, wherein polymerization is carried out at a temperature between ambient temperature and 75 C.

16. The method according to claim 1, wherein the polymer is in the form of an aqueous composition comprising the inverse emulsion with an aqueous phase comprising the polymer dispersed in the form of droplets in a hydrophobic external phase and other ingredients chosen from a surfactant, an organic salt, an inorganic salt, a detergent and a thickener.

17. The method according to claim 1, wherein the saline composition is based on seawater or on a brine.

18. The method according to claim 16, wherein the aqueous composition is a fluid for use in civil engineering for excavating and/or digging operations, a composition for household care, or a cosmetic composition.

19. The method of claim 1, wherein the polymer is effective to promote the suspending of the dispersed solid or liquid particles in the aqueous medium at a temperature of greater than or equal to 100 C.

20. The method of claim 1, wherein the polymer is prepared by inverse emulsion polymerization of at least one monomer Ab comprising sulphopropyldimethylammoniopropylmethacrylamide and one or more nonionic monomers Ba, wherein the amount of sulphopropyldimethylammoniopropylmethacrylamide is at least 10 mole % of the combined amount of monomers Ab and monomers Ba.

21. The method of claim 20, wherein the polymer is effective to promote the suspending of the dispersed solid or liquid particles in the aqueous medium at a temperature of greater than or equal to 150 C.

22. The method of claim 1, wherein the suspension comprises greater than or equal to 1% but less than or equal to 20% by weight of the polymer.

Description

EXAMPLE 1 (COMPARATIVE)

Solution Polymerization-poly(acrvlamide/SPP) 90/10 mol/mol

(1) Copolymerization:

(2) 82.4 g of 50% acrylamide in water, 18.8 g of SPP and 94.4 g of water are added to a 500 ml three-necked round-bottom flask equipped with a nitrogen inlet, a mechanical stirrer (anchor), a reflux condenser and temperature regulation via a thermostatically controlled bath of oil. The temperature of the reaction medium is brought to 65 C. while flushing with nitrogen. 0.3 g of sodium persulphate dissolved in 5 g of water is added at 65 C. The temperature of the reaction medium is maintained for 24 h. The combined mixture is subsequently cooled to ambient temperature. The final product exists in the form of a translucent gel.

(3) The molar mass of the polymer obtained can be conventionally adjusted by modifying the amount of initiator introduced, the reaction temperature or the addition of a transfer agent. The concentrations of initiator and the corresponding molar masses, reported as weight average molecular weight (Mw), as determined by steric exclusion chromatography are set forth in Table 1 below:

(4) TABLE-US-00001 TABLE 1 Mw by Concentration of initiator with chromatography Example respect to the monomers (kg/mol) 1-1 0.2% + transfer agent 63 1-2 5% 370

EXAMPLE 2

Inverse Emulsion Polymerization-poly(acrylamide/SPP) 90/10 mol/mol

(5) The synthesis takes place in two stages: preparation of an emulsion comprising the monomers and the surfactants, followed by copolymerization.

(6) Preparation of an Emulsion Comprising the Monomers and the Surfactants:

(7) 110.2 g of Shellsol D80 (Shell Chemicals), 18.5 g of G946 (ICI), 9.3 g of Rhodasurf LA-3 (Rhodia) and 4.9 g of Hypermer B261 (Uniquema) are added to a 250 ml glass beaker with magnetic stirring. Stirring is maintained until a clear solution is obtained (Mixture 1). 199.8 g of 50% acrylamide in water, 91.3 g of 50% SPP in water, 0.2 g of Versene 100 (Dow) and 2.9 g of sodium sulphate are added to a 500 ml glass beaker with magnetic stirring. Stirring is maintained until a clear solution is obtained (Mixture 2). Mixture 2 is subsequently introduced into Mixture 1 with magnetic stirring. Stirring is maintained for 5 min and then all the liquid is added to a mixer of rotor/stator type in order to be mixed for 10 s (6000 revolutions/min). The stable emulsion is thus obtained.

(8) Copolymerization

(9) All the emulsion prepared immediately above is added to a 1 liter jacketed glass reactor equipped with a nitrogen inlet, a mechanical stirrer, a reflux condenser and temperature regulation via a thermostatically controlled bath. The temperature of the reaction medium is brought to 45 C. while flushing with nitrogen. 0.2 g of Trigonox 25C75 (Akzo Nobel) is added at 45 C. An additional 0.2 g of Trigonox 25C75 is added 4 hours after this addition. The temperature of the reaction medium is subsequently brought to 55 C. for 3 h. The combined mixture is cooled to ambient temperature.

(10) The final emulsion exists in the form of a translucent and slightly coloured liquid which is not very viscous.

(11) By following the procedure described above, polymers of variable molar masses are produced by modifying the level of initiator. However, for numerous tests, the molar masses are too high to be measured by steric exclusion chromatography. The molar masses are certainly significantly greater than 310.sup.6 g/mol. Furthermore, copolymers with variable acrylamide/SPP ratios are also synthesized. The characteristics of the products are referenced in Table 2 below:

(12) TABLE-US-00002 TABLE 2 Mw by chromatography Example Operating conditions (kg/mol) 2-1 concentration initiator = 0.1 mol % vs 2000 monomers, T = 65 C., [Am]/[SPP] = 90/10 mol/mol 2-2 concentration initiator = 0.05 mol % vs not measurable monomers, T = 65 C., [Am]/[SPP] = 90/10 mol/mol 2-3 concentration initiator = 0.05 mol % vs not measurable monomers, T = 55 C., [Am]/[SPP] = 90/10 mol/mol 2-4 concentration initiator = 0.1 mol % vs not measurable monomers, [Am]/[SPP] = 90/10 mol/mol 2-5 concentration initiator = 0.02 mol % vs not measurable monomers, [Am]/[SPP] = 90/10 mol/mol 2-6 concentration initiator = 0.1 mol % vs not measurable monomers, [Am]/[SPP] = 98/2 mol/mol 2-7 concentration initiator = 0.1 mol % vs not measurable monomers, [Am]/[SPP] = 95/5 mol/mol 2-8 concentration initiator = 0.1 mol % vs not measurable monomers, [Am]/[SPP] = 80/20 mol/mol 2-9 concentration initiator = 0.1 mol % vs not measurable monomers, [Am]/[SPP] = 70/30 mol/mol 2-10 concentration initiator = 0.1 mol % vs not measurable monomers, [Am]/[SPP] = 50/50 mol/mol

EXAMPLE 3

Evaluations

(13) The viscosities of the polymer solutions are evaluated using an AR2000 rheometer (TA Instrument, Surrey, United Kingdom) provided with geometry of Couette type (internal radius=14 mm; external radius=15 mm and height=42 mm).

(14) Molar Masses

(15) The viscosity contributed by the dissolution of a polymer is represented by its intrinsic viscosity (the linear extrapolation to zero concentration of the reduced specific viscosity:

(16) $\left[\right]=\underset{c.fwdarw.0}{\lim }\frac{-{}_0}{{}_{0}c},$
where is the viscosity of the solution comprising the polymer, .sub.0 is the viscosity of the solvent and c is the concentration of polymer.

(17) The intrinsic viscosity, for a polymer chemical composition under given solvent conditions, is related to the molar mass by the Mark-Houwink relationship (Polymer Handbook (4.sup.th edition), J. Brandrup, E. H. Immergut and E. A. Grulke, Wiley (1999)):
[]=KM.sup.a
wherein K and a are constants which depend on the chemical composition of the polymer and on the solvent and temperature.

(18) The polymers of Examples 1 and 2 are purified and dried and then dissolved in a 20% by weight NaCl solution at different concentrations of polymer. The reduced specific viscosity curves as a function of the polymer concentration make it possible to determine the intrinsic viscosity given in Table 3 below.

(19) TABLE-US-00003 TABLE 3 Mw by chromatography Intrinsic viscosity Example (kg/mol) (mL/g) Solution 1-1 63 37 Solution 1-2 370 112 Inverse emulsion 2-1 2000 320 Inverse emulsion 2-2 not measurable 470 Inverse emulsion 2-3 not measurable 550 Inverse emulsion 2-4 not measurable 850 Inverse emulsion 2-5 not measurable 1100
Rheology in Saline Solutions

(20) The copolymers described in Examples 1 and 2 are used in the solutions of variable salinities described in Table 4 below.

(21) TABLE-US-00004 TABLE 4 Composition (w salt per Viscosity at Reference 1 kg of solution) Density 25 C. (mPa .Math. s) ZnBr.sub.2/CaBr.sub.2 ZnBr.sub.2 550 g/CaBr.sub.2 230 g 2.3 25.2 CaCl.sub.2/CaBr.sub.2 CaCl.sub.2 230 g/CaBr.sub.2 330 g 1.7 5.9 45% NaBr NaBr 446 g 1.5 2.4 20% NaCl NaCl 200 g 1.15 1.48 10% NaCl NaCl 100 g 1.07 1.2 5% NaCl NaCl 50 g 1.03 1.0 Purified water / 0.99 0.95

(22) The polymers are purified and dried. The powders obtained are dissolved at 10 g/l with magnetic stirring. The viscosities are measured 72 h after the preparation of the samples and the values obtained are collated in Table 5 below.

(23) TABLE-US-00005 TABLE 5 Relative viscosity at a polymer concentration at 10 g/l (gradient of 1 s.sup.1 at 25 C.) Relative Relative Relative Relative Intrinsic viscosity: viscosity: viscosity: viscosity: viscosity Purified 5% 10% 20% Example (mL/g) water NaCl NaCl NaCl Solution 1-1 37 1.3 1.5 1.3 1.4 Solution 1-2 112 2.5 2.3 2.1 2.4 Inverse 2-1 320 14 10 9.2 11 emulsion Inverse 2-2 470 16 18 19 22 emulsion Inverse 2-3 550 51 60 72 82 emulsion Inverse 2-4 850 59 98 102 108 emulsion Inverse 2-5 1100 100 179 165 196 emulsion

(24) These results demonstrate that the viscosifying power of the polymers according to the invention increases as the molar mass (i.e. the intrinsic viscosity) increases and as the salinity increases.

(25) Direct Dispersion

(26) The polymers of Example 2, synthesized by inverse emulsion polymerization with the composition Am/SPP (90/10), are dispersed directly in the brines.

(27) 5% by weight of surfactant Soprophor 4D384 (Rhodia) are added to the inverse emulsion 5 minutes before mixing with the brines. The amount necessary to obtain 10 g/l of polymer is dispersed in the brines. These preparations are, in a first step, stirred vigorously by hand for a few moments and then stirred with a magnetic bar until they are used.

(28) Relative viscosities at a polymer concentration of 10 g/l are measured here 24 h after the preparation of the samples (gradient of 1 s.sup.1 at 25 C.) and the values are collated in Table 6 below.

(29) TABLE-US-00006 TABLE 6 Relative Relative Relative Intrinsic viscosity viscosity: viscosity: viscosity: Example (mL/g) NaBr CaCl.sub.2/CaBr.sub.2 ZnBr.sub.2/CaBr.sub.2 2-1 320 17 25 115 2-2 470 59 110 529 2-3 550 77 217 549 2-4 850 114 437 797

(30) These results demonstrate that the viscosifying power of the polymers according to the invention is very high in brines highly concentrated in salt.

(31) High-temperature Stability

(32) Solutions of polymers comprising variable levels of SPP are prepared according to the protocol described in Example 2 at a concentration by weight of 0.5% in the brine ZnBr.sub.2/CaBr.sub.2.

(33) The viscosities of these solutions are measured after mixing at ambient temperature and then after ageing in pressurized cells (acid digestion bombsParr instruments) in a rolling oven at 160 C. for 6 h.

(34) The aged solutions may exhibit solid residues; if appropriate, these solutions are filtered through a 100 m cloth. The viscosities are then measured at 90 C. and the values are collated in Table 7 below.

(35) TABLE-US-00007 TABLE 7 Relative viscosity at a polymer concentration of 0.5% by weight (gradient of 100 s.sup.1 at 90 C.) SPP level Relative viscosity: Relative viscosity: Example (mol %) initial solution solutions aged at 160 C. 2-6 2 51 1.0 Precipitate 2-7 5 53 1.1 Precipitate -4 10 60 9.7 Homogeneous solution 2-8 20 33 8.8 Homogeneous solution 2-9 30 13.5 11.2 Homogeneous solution 2-10 50 5.5 4.8 Homogeneous solution

(36) These results demonstrate that the high-temperature stability of the polymers according to the invention dissolved in brines is directly related to the level of SPP incorporated in the polymer. In this instance, a minimum level of 10 mol % is necessary to maintain the homogeneity of the solution if the latter is exposed for a long time to high temperatures.