ENCAPSULATED ACTIVATOR AND ITS USE TO TRIGGER A GELLING SYSTEM BY PHYSICAL MEANS

Abstract

A process allowing the encapsulation of a polymerization accelerator comprising the steps of: a) providing an reverse emulsion containing, in an oil phase, a water solution/dispersion containing the polymerisation activator, the oil phase including a heat curable mixture of an isocyanate and a polyalkyldiene hydroxylated or polyol, b) pouring the reverse emulsion in a water phase to make a multiple emulsion water/oil/water, containing drops of activators as the internal water phase, and then, c) heating the multiple emulsion obtained in step b) to cure the polyisocyanate in polyurethane and obtain drops of activator enclosed in shells of polyurethane dispersed in water. The invention also relates to aqueous gelling systems comprising the encapsulated polymerization accelerator with water soluble or dispersable monomers and a polymerization initiator dispersed in said monomers, useful i.a. for sealing subterranean environments or consolidation of a soil or sealing of a subterranean structure.

Claims

1-6. (canceled)

7. The gelling system of claim 12, wherein the polymerisation accelerator is an alkylamine, polyalkyleneamine, or polyalkylenimine.

8. The gelling system of claim 12, wherein the hydroxylated polyalkyldiene or polyol is a hydroxylated polybutadiene.

9. The gelling system as claimed in claim 12, wherein the isocyanate is a trimer form of alpha, omega hexyldiisocynate.

10. The gelling system of claim 9, wherein the polymerisation accelerator is a polyethyleneimine (PEI).

11. The gelling system of claim 12, wherein a polymerization initiator is encapsulated with the polymerization accelerator, wherein the polymerization initiator is selected from the group consisting of and water soluble persalts and/or peroxides.

12. The aqueous gelling system of claim 25, comprising: i) the water soluble or dispersable monomers comprising acrylated or methacrylated polyoxyethylene and/or polyoxypropylene monomers p1 ii) the polymerization initiator dispersed in said monomers i), and iii) the encapsulated polymerization accelerator, wherein the encapsulated polymerization accelerator is obtained in a process comprising the steps of: a) providing a reverse emulsion containing, in an oil phase, a water solution or dispersion (W1) containing said polymerisation accelerator, the oil phase including a heat curable mixture of an isocyanate and a hydroxylated polyalkyldiene or polyol, b) pouring the reverse emulsion of step a) in a water phase (W2) to make a water/oil/water multiple emulsion, containing drops of the water solution or dispersion comprising the accelerator as the internal water phase and, then, c) curing the mixture of isocyanate and hydroxylated polyalkyldiene or polyol in the the multiple emulsion obtained in step b) to obtain polyurethane and enclose the drops of the water solution or dispersion comprising the accelerator in shells of the polyurethane dispersed in water, wherein the shells of polyurethane have an average diameter between 300 and 1500 m.

13. The gelling system of claim 12, wherein the polymerization initiators are encapsulated with the polymerization accelerator.

14. The gelling system of claim 12, wherein the water soluble or water dispersable acrylated or methacrylated polyoxyethylene and/or polyoxypropylene monomers have the general formula:
CH.sub.2CR.sup.1CO(OCH.sub.2CHR.sup.2).sub.nOR.sup.3(1) wherein: R.sup.1 is a hydrogen atom or a methyl radical, R.sup.2 is a hydrogen atom or a methyl radical, and R.sup.3 is a hydrogen atom, a methyl radical, or a CH.sub.2CR.sup.1CO group, n is a whole or fractional number from 3 to 25.

15. The gelling system of claim 14, wherein the water soluble or water dispersable acrylated or methacrylated polyoxyethylene and/or polyoxypropylene monomers is a mixture of methacrylate modified polyethylene oxide of the formulae: formulae: ##STR00003## wherein n is a number between 15 and 25, limits included, and/or ##STR00004## wherein n is a number between 10 and 20, limits included.

16. The gelling system of claim 14, wherein the water soluble or water dispersable monomers is a mixture comprising at least two distinct kinds of monomers, obtained by reacting a mixture of two compounds (A1) and (A2) having the following formulae:
HO(OCH.sub.2CHR.sup.2).sub.nMe (A1)
HO(OCH.sub.2CHR.sup.2).sub.nOH (A2) wherein R2 is as defined in claim 14, with a (meth)acrylic acid, chloride or anhydride, typically a (meth)acrylic anhydride of formula (CH2CR1C)2O wherein R1 is as defined in claim 14.

17. A process for sealing subterranean environments and consolidation of a soil or sealing of a subterranean structure, comprising underground railway tunnels, sewers, underground car parks, storage ponds, swimming pools, oil wells, mine shafts and dams, comprising the steps of: e1) injecting into said environments soil or structure an aqueous gelling system of claim 25, comprising a polymerization accelerator encapsulated in polyurethane capsules and monomers; and e2) triggering the polymerisation of the resin by physical means, for example high shear, high pressure, temperature, crushing, and/or shearing, whereby the encapsulated polymerization accelerator is released from the polyurethane capsules.

18. The gelling system of claim 12, wherein the polymerisation accelerator is an alkylamine, polyalkyleneamine or polyalkylenimine comprising tertiary amino groups and whose alkyl or alkylen part comprises 2-4 carbon atoms.

19. The gelling system of claim 16, wherein R1 is with a molar ratio (A2)/(A 1) of between 10:90 to 50:50.

20. The gelling system of claim 17, wherein said physical means is selected from the group consisting of high shear, high pressure, temperature, crushing, shearing, and any combination thereof.

21. The gelling system of claim 12, wherein the isocyanate is alpha, omega alkyldiisocynate.

22. The gelling system of claim 12, wherein the shells of polyurethane have an average diameter between 300 and 800 m.

23. An aqueous gelling system comprising: i) water soluble or dispersable monomers comprising acrylated or methacrylated polyoxyethylene and/or polyoxypropylene monomers ii) a polymerization initiator dispersed in said monomers i), and iii) an encapsulated polymerization accelerator comprising drops of activator enclosed in shells of polyurethane dispersed in water, wherein the polymerisation accelerator is a polyethyleneimine (PEI).

24. An aqueous gelling system comprising: i) water soluble or dispersable monomers comprising acrylated or methacrylated polyoxyethylene and/or polyoxypropylene monomers ii) a polymerization initiator dispersed in said monomers i), and iii) an encapsulated polymerization accelerator comprising drops of activator enclosed in shells of polyurethane dispersed in water, wherein a polymerization initiator is also encapsulated in the shells with the polymerization accelerator, wherein the polymerization initiator is selected from the group consisting of water soluble persalts and/or peroxides.

25. An aqueous gelling system comprising: i) water soluble or dispersable monomers comprising acrylated or methacrylated polyoxyethylene and/or polyoxypropylene monomers ii) a polymerization initiator dispersed in said monomers i), and iii) an encapsulated polymerization accelerator comprising drops of activator enclosed in shells of polyurethane dispersed in water, wherein the shells of polyurethane have an average diameter between 300 and 1500 m.

Description

EXAMPLE 1

[0057] A specific gelling system was prepared by following the following steps:

[0058] step a):

[0059] the aqueous solution of Polyethyleneimine (PEI, Lupasol P from BASF) is dispersed in mixture of OH functionalized butadiene (Poly BD R45HT-LO from Sartomer), isophorone di-isocyanate trimer supplied diluted with 30% wt butyl acetate (Tolonate IDT 70B from Perstorp) and diluted with Rhodiasolv DIB (succinate, glutarate, adipate diisobutyl ester from Rhodia).

[0060] In order to ease the emulsification process, the emulsion of PEI in OH functional butadiene diluted with DIB is first made, and, then, the isocyanate is added to the already formed emulsion.

[0061] The particle size of the emulsion is set by acting on the agitation speed.

[0062] The different quantities of ingredients are gathered in the following table 1:

TABLE-US-00001 TABLE 1 Ingredients Weight (g) OH functionalized butadiene Poly BD R45HT-LO 186.9 from Sartomer DIB 186.9 PEI 532.7 Tolonate IDT 70B from perstorp 93.5 Total 1000.0

[0063] The mixing time after the addition of isocyanate is set to 5 mn. As a consequence, the reverse emulsion is quickly transferred to the aqueous phase to form the multiple emulsion of step b)

[0064] Step b)

[0065] The reverse emulsion from step a) is then dispersed under vigorous stirring conditions to achieve the multiple emulsion. A very good and homogeneous mixing efficiency is needed at that stage to maintain a particle size distribution as narrow as possible.

[0066] To stabilize the suspension and avoid bursting of the capsules while the polyurethane is not fully crosslinked the dispersion is made in a salted xanthan solution. The salt (here NaCl at 20% wt) ensure the osmotic pressure balance between the inner PEI and outer xanthan solution phases. A mismatch of osmotic pressure would cause a burst of the inverse emulsion. Xanthan is used here as a protective colloid and rheological agent. Indeed, it shows very good suspensive properties as well as stabilization of the emulsion in salt water and even at elevated cure temperature (up to 80 C. here).

[0067] As long as an homogeneous mixing is ensured during step b), the particle size distribution is directly linked to the mixing speed. Here a rotation speed of 280 RPM gives a particle size of approx 400 m.

[0068] Typical operating conditions are reported here below: [0069] transfer of emulsion of step a) to the reactor (containing the 0.45% wt xanthan in 20% wt NaCl water solution) under shear 280 RPM heated to 66 C. (envelope temperature) [0070] after addition maintain agitation at 280 RPM for 15 mn [0071] reduce speed to minimal 37 RPM and maintain for 2 hrs for curing of the elastomer

[0072] For 1000 g emulsion from step 1 quantities necessary for the second step are reported in table 2 below:

TABLE-US-00002 ingredients weight(g) deionized water 700.7 xanthan (Rhodopol 23P) 4.0 NaCI Normapur 177.0 Total 881.7

EXAMPLE 2

[0073] In a nitrogen rented round bottom flask, a mixture of methoxy polyethylene glycol (M=750 g/mol) and polyethylene glycol (M=1000 g/mol) respectively 67% and 33% by weight was poured at 50 C. Methoxy polyethylene glycol and polyethylene glycol are bearing respectively 1 and 2 OH function per molecule.

[0074] The necessary quantity of methacrylic anhydride (AM2O) to get a molar ratio of AM2O/OH=1 is added to the reaction medium. Prior use, AM20 was stabilized with 1000 ppm phenothiazine and 1000 ppm topanol.

[0075] The quantities and the nature of the used products are reported in the table 3 below:

TABLE-US-00003 supplier purity M (g/mol) m(g) methacrylic anhydride AM2O 94% 154.16 25.5 Aldrich PEG 1000 Fluka 100% 1000 33 methoxy PEG 750 Aldrich 100% 750 67 phenothiazine Acros 99% 199.3 0.024 topanol A brenntag 78.5-100% 178 0.024

[0076] The reaction medium was heated up to 80 C. for 10 hrs under stirring of a magnetic bar (with an expected yield of esterification is 80%).

[0077] Flask was then placed under vacuum (30 mbars) and heated to 90 C. Under these pressure and temperature conditions, produced methacrylic adic was removed by vapor stripping. Stripping was considered as complete when residual methacrylic acid content is below 2%. The obtained product is diluted with water to 70%. This material will hereinafter be referred to as PEO-methacrylate monomers.

EXAMPLE 3

[0078] The capsules from example 1 are formulated with a PEO-methacrylate monomers from example 2.

[0079] Formulations are thickened using hydroxyl-ethyl cellulose (HEC) Cellosize 10-HV from Dow. The solid polymer is hydrated for at least 1 hr under stirring in de-ionized water at 0.5% wt prior use.

[0080] Other components are gently mixed together in quantities as reported in table 4 below:

TABLE-US-00004 formulation #2-1 formulation #2-2 formulation m (g) m (g) PEO-methacrylate monomers 3.75 3.75 HEC at 0.5% 21.25 21.25 Sodium persulfate 0.125 0.25 capsules from example 1 0.25 0.25

[0081] Half of each formulation is sheared for 10 secs at 16000 RPM using a rotor stator blender (Ultra-Turrax 125 basic from IKA). Solution of both sheared and un-sheared formulations are then let set at 21 C. and setting times are reported in table 5 below.

TABLE-US-00005 formulation #2-1 formulation #2-2 Sheared ultra turrax gelification after gelification after 105 mn 65 mn un-sheared gelification after gelification after 25 hrs 21 hrs

[0082] The results gathered in the above table, shows that shear from rotor stator blender can release the polymerization activator and induce gelification of the formulation.

EXAMPLE 4

High Temperature Formulation

[0083] In order to ensure a proper temperature stability for the POE-methacrylate monomers at high temperature, a more thermally stable oxidizer is used and an extra inhibitor is added to the system. The inhibitor used here is the 4-Hydroxy-2,2 6,6-tetramethylpiperidine 1-oxyl (or hydroxyl-TEMPO)

[0084] The capsules from example 1 are formulated with a PEO-methacrylate monomers from example 2.

[0085] Formulations are thickened using hydroxyl-ethyl cellulose (HEC) Cellosize 10-HV from Dow. The solid polymer is hydrated for at least 1 hr under stirring in de-ionized water at 0.5% wt prior use.

[0086] Other components are gently mixed together in quantities as reported in table 6 below.

TABLE-US-00006 formulation #3-1 Formulation m (g) PEO-methacrylate monomers 3.75 HEC at 0.5% 21.25 tertiobutyl hydroperoxide @ 70% in water 0.10 capsules from example 1 0.25 Hydroxy-TEMPO @ 1% in water 0.19

[0087] Then half of the formulation is sheared for 10 secs at 16000 RPM using a rotor stator blender (Ultra-Turrax T25 basic from IKA). Solution of both sheared and un-sheared formulations are placed in an oven heated at 80 C. and setting times are reported in table below.

TABLE-US-00007 formulation #3 sheared ultra turrax 45 mn un-sheared 210 mn

[0088] Considering that in the oven, samples take about 60 minutes to reach 80 C. and are at 65 C. after 45 mn, the above shows that a sheared sample is activated very quickly once at elevated temperature while an un-sheared sample remains stable for a couple of hours at 80 C. without any reaction.