U.S. patent application number 10/483202 was filed with the patent office on 2004-11-04 for aqueous compositions comprising a chemical microgel associated with an aqueous polymer.
Invention is credited to Bavouzet, Bruno, Destarac, Mathias.
Application Number | 20040219215 10/483202 |
Document ID | / |
Family ID | 8865497 |
Filed Date | 2004-11-04 |
United States Patent
Application |
20040219215 |
Kind Code |
A1 |
Bavouzet, Bruno ; et
al. |
November 4, 2004 |
Aqueous compositions comprising a chemical microgel associated with
an aqueous polymer
Abstract
The invention concerns an aqueous composition comprising
particles of a water-soluble or water-dispersible chemical
microgel, associated with at least a water-soluble or
water-dispersible crosslinking polymer, differing in composition
from the particles; the amount of chemical microgel particles
ranging between 0.05 to 40% by dry weight of the composition and
the amount of crosslinking polymer being such that the viscosity of
the composition is at least three times higher than that of an
aqueous solution of chemical microgel particles and than that of an
aqueous solution of crosslinking polymer, in similar conditions.
The invention also concerns said composition, its use and
formulations comprising same.
Inventors: |
Bavouzet, Bruno; (Paris,
FR) ; Destarac, Mathias; (Paris, FR) |
Correspondence
Address: |
Jean Louis Seugnet
Intellectual Property Department
Rhodia Inc CN7500
259 Prospect Plains Road
Cranbury
NJ
08512-7500
US
|
Family ID: |
8865497 |
Appl. No.: |
10/483202 |
Filed: |
May 24, 2004 |
PCT Filed: |
July 15, 2002 |
PCT NO: |
PCT/FR02/02512 |
Current U.S.
Class: |
424/486 |
Current CPC
Class: |
C08J 3/005 20130101;
C08J 3/075 20130101; C08F 293/005 20130101 |
Class at
Publication: |
424/486 |
International
Class: |
A61K 009/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 13, 2001 |
FR |
01/09387 |
Claims
1-23. Canceled
24. An aqueous composition comprising particles of hydrosoluble or
hydrodispersible chemical microgel associated with at least one
hydrosoluble or hydrodispersible bridging polymer with a chemical
composition that differs from that of said particles; the chemical
microgel particles being in a quantity in the range 0.05% to 40% of
the dry weight of the composition and the bridging polymer being in
a quantity such that the composition has a viscosity of at least
three times that of an aqueous solution of chemical microgel
particles and that of an aqueous solution of bridging polymer under
the same conditions.
25. The aqueous composition according to claim 24, wherein the
quantity of chemical microgel particles is in the range 0.05% to
10% of the dry composition weight.
26. The aqueous composition according to claim 24, wherein the
quantity of bridging polymer is such that the mixture of chemical
microgel particles and bridging polymer is hydrosoluble or
hydrodispersible.
27. The aqueous composition according to claim 24, wherein the
chemical microgel particles are constituted by at least one
chemically cross-linked hydrosoluble or hydrodispersible
polymer.
28. The composition according to claim 24, wherein the polymer has
a number of hydrosoluble motifs representing at least 50% of the
number of motifs of the polymer.
29. The composition according to claim 24, wherein the chemical
microgel particles has a number average size in the range 0.3 .mu.m
to 10 mm.
30. The composition according to claim 24, wherein the bridging
polymer is constituted by at least one polymer with a theoretical
molar mass in the range 10.sup.3 to 5.times.10.sup.7 g/mol by
weight.
31. The composition according to claim 24, wherein the polymers
from which the chemical microgel particles and the bridging polymer
are derived are obtained at least starting from hydrophilic, non
ionic, ionic or potentially ionizable and optionally hydrophobic
monomers.
32. The composition according to claim 24, wherein the non ionic
hydrophilic monomers are ethylene oxide; amides of linear or
branched, cyclic or aromatic mono- or polycarboxylic acids,
comprising at least one ethylenically unsaturated bond;
2-hydroxyethyl (meth) acrylate; or vinyl esters producing polyvinyl
alcohol blocks after hydrolysis.
33. The composition according to claim 32, wherein the ionic or
potentially ionic hydrophilic monomers are anionic or potentially
anionic monomers carrying at least one carboxylic, sulphonic,
sulphuric, phosphonic, phosphoric or sulphosuccinic function.
34. The composition according to claim 32, wherein the anionic or
potentially anionic monomers are: linear or branched, cyclic or
aromatic mono- or poly-carboxylic acids, N-substituted derivatives
of said acids, or monoesters of poly-carboxylic acids, comprising
at least one ethylenically unsaturated bond; linear or branched,
cyclic or aromatic vinyl carboxylic acids; or aminoacids comprising
one or more ethylenically unsaturated bonds.
35. The composition according to claim 32, wherein the ionic or
potentially ionic hydrophilic monomers are cationic or potentially
cationic monomers being: aminoalkyl (meth)acrylates, aminoalkyl
(meth)acrylamides; monomers comprising at least one secondary,
tertiary or quaternary amine function, or a heterocyclic group
containing a nitrogen atom, vinylamine, ethylene imine; or
diallyldialkyl ammonium salts.
36. The composition according to claim 32, wherein the ionic or
potentially ionic hydrophilic monomers further comprise one or more
amphoteric and/or zwitterionic monomers.
37. The composition according to claim 32, wherein the polymers
from which the polymer particles and the bridging species are
derived are obtained from at least one hydrophobic monomer being:
propylene oxide, butylene oxide; esters of linear or branched,
cyclic or aromatic mono- or poly-carboxylic acids comprising at
least one ethylenically unsaturated bond; .alpha..beta.
ethylenically unsaturated nitrites, vinyl ethers, vinyl esters,
vinylaromatic monomers, vinyl or vinylidene halides; or linear or
branched, aromatic or non aromatic hydrocarbon monomers comprising
at least one ethylenically unsaturated bond. The composition
according to one of the preceding claims, wherein the bridging
polymer comprises at least one polymer selected from chemically
modified or non modified biopolymers.
38. The composition according to claim 24, wherein the biopolymers
are galactomannans, glucoomannans, succinoglycans, xanthan gum,
cellulose, alginates or gelatin.
39. The composition according to claim 24, wherein the chemical
microgel particles and the bridging polymer are further associated
by electrostatic interactions; the chemical microgel particles
having overall charge being opposite to the overall charge of the
bridging polymer.
40. The composition according to claim 24, wherein the chemical
microgel particles and the bridging polymer are further associated
by means of hydrophobic-hydrophobic type interactions; the chemical
microgel particles and the bridging polymer comprising motifs
associating together in an aqueous phase by means of said
interactions.
41. The composition according to claim 24, wherein the chemical
microgel particles and the bridging polymer are associated by means
of hydrogen bond interactions: the chemical microgel particles and
the bridging polymer comprising motifs associating together in an
aqueous phase by means of said bonds.
42. A process for preparing a composition as defined in claim 24,
comprising the following steps: a) preparing a chemical gel in an
aqueous phase by polymerizing the desired monomer or monomers and a
crosslinking agent, or by chemical post-polymerization
cross-linking of a polymer; b) grinding the resulting gel to obtain
chemical microgel particles; and c) bringing said chemical microgel
particles into contact with at least one bridging polymer in an
aqueous phase.
43. A process for preparing a composition as defined in claim 24,
comprising the following steps: 1) preparing particles of chemical
microgel by polymerizing the desired monomer or monomers and a
cross-linking agent in micro-reactors and/or with stirring and/or
in the presence of at least one limiting agent, or by chemical
post-polymerization cross-linking of a polymer in micro-reactors
and/or with stirring; and 2) bringing said chemical microgel
particles into contact with at least one bridging polymer in an
aqueous phase.
44. Formulations for oil or gas field working, detergents and
cosmetics, comprising the composition as defined in claim 24, in
the fields.
Description
[0001] The present invention relates to aqueous compositions
comprising particles of chemical microgel associated with at least
one bridging polymer, more particularly in the form of a viscous
fluid or a gel.
[0002] It also relates to the preparation of said aqueous
compositions, to their uses, and formulations comprising them.
[0003] Essentially, two types of gel are known: chemical gels and
physical gels.
[0004] One of the principal advantages of chemical gels resides in
the fact that they have a relatively high modulus of elasticity:
their behaviour is good when the temperature varies. Further, they
may have a weak sensitivity towards the introduction of
conventional additives such as bases, acids, surfactants, etc. Such
systems, however, are not reversible on shearing, which greatly
limits their use. In fact, in current applications, gels used under
shear are required to regain their initial viscosity in the absence
of the shear. Chemical gels do not possess such
characteristics.
[0005] This characteristic of at least partial reversibility exists
for physical gels. After undergoing shear, they have the capacity
of regaining the viscosity of the fluid prior to the shear
operation. Further, such gels often have a shear thinning type
rheological profile (the viscosity of the gel reduces with
increasing shear). The difficulty is that the rheological
characteristics of such gels are modified uncontrollably if they
are subjected to external variations in temperature and possibly in
chemical composition (by adding other compound), etc. Further, such
gels are actually viscoelastic fluids which have gel properties
over short periods but viscous characteristics over long
periods.
[0006] One aim of the present invention is to propose a gel which
combines the characteristics of stability not only of chemical type
gels, but also of physical type gels.
[0007] These and other aims are achieved in the present invention,
which provides an aqueous composition comprising particles of
hydrosoluble or hydrodispersible chemical microgel associated with
at least one hydrosoluble or hydrodispersible bridging polymer with
a chemical composition that differs from that of said particles;
the quantity of chemical microgel particles being in the range
0.05% to 40% of the dry weight of the composition and the quantity
of bridging polymer being such that the viscosity of the
composition is at least three times, preferably at least ten times
that of an aqueous solution of chemical microgel particles and that
of an aqueous solution of bridging polymer under the same
conditions.
[0008] The present invention also relates to a first process for
preparing said composition, in which:
[0009] a) a chemical gel is prepared in an aqueous phase by
polymerizing the desired monomer or monomers and a crosslinking
agent, or by chemical post-polymerization cross-linking of a
polymer;
[0010] b) the resulting gel is ground to obtain chemical microgel
particles;
[0011] c) said chemical microgel particles are brought into contact
with at least one bridging polymer in an aqueous phase.
[0012] It concerns a second process for preparing a composition in
which the following steps are carried out:
[0013] a) preparing particles of chemical microgel by polymerizing
the desired monomer or monomers and a cross-linking agent in
micro-reactors and/or with stirring and/or in the presence of at
least one limiting agent, or by chemical post-polymerization
cross-linking, in micro-reactors and/or with stirring, of a
polymer;
[0014] b) bringing said chemical microgel particles into contact
with at least one bridging polymer in an aqueous phase.
[0015] The composition of the invention has the advantage of
forming a gel which is at least partially or even completely
reversible. The rheological profile of the aqueous composition is
generally shear thinning in type. Thus, when the composition
undergoes shear, the viscosity reduces and increases again or may
even resume the initial viscosity when shearing is stopped. In the
case in which the rheological profile is shear thickening in
nature, reversibility similarly results in the viscosity reducing
again or even recover of the initial viscosity when shearing is
stopped. Further, the composition of the invention forms a gel
which preserves its rheological properties better under constraints
of temperature under shear, for example, while conventional
physical gels lose them.
[0016] It should also be noted, and this constitutes a definite
advantage, that depending on the nature of the microgel particles
and the bridging polymer, the rheological behaviour of the
composition can be adapted as a function of the pH (pH responsive
gels).
[0017] Other characteristics and advantages of the present
invention will become apparent from the following description and
examples.
[0018] It should be noted that the aqueous composition of the
invention can be in the form of a gel. More precisely, the term
"gel" means compositions with a modulus of elasticity (G') that is
greater than or equal to the loss modulus (G") over a frequency
range in the range 1 to 10 Hz, using a cone-plate geometry; the
modules were measured in the linear viscoelastic region, at
25.degree. C., with a Rheometrics or Carrimed rheometer.
[0019] Further, unless otherwise indicated, the viscosities were
measured using a Carrimed type viscosimeter, with a cone-plate
geometry; the measurements were made at 25.degree. C. at a shear
rate of 1 s.sup.-1.
[0020] Further, the temperature and composition pH conditions given
below concern the composition per se prior to use, comprising the
copolymer and the charged species, or associated with various other
constituents necessary to obtaining complete formulations. These
"conditions" can also concern the composition during its use, more
specifically during use of the complete formulation.
[0021] It should also be pointed out that the term "polymers"
designates both homopolymers and copolymers.
[0022] The bridging polymer is termed hydrosoluble or
hydrodispersible when no macroscopic phase separation phenomena are
observed when it is in solution or dispersion in an aqueous phase,
after one hour under the same conditions of concentration and
temperature as those of the composition of the invention.
[0023] Further, the term "particles of hydrosoluble or
hydrodispersible chemical microgel" means particles of chemically
cross-linked polymer swelled by an aqueous solution.
[0024] As indicated above, one of the first constituents of the
aqueous composition of the invention is constituted by hydrosoluble
or hydrodispersible particles of chemical microgel.
[0025] More particularly, the quantity of chemical microgel
particles is in the range 0.05% to 10% of the dry composition
weight, preferably in the range 0.1% to 5% of the dry composition
weight.
[0026] In accordance with an advantageous implementation of the
invention, the number average size of the chemical microgel
particles is in the range 0.3 .mu.m to 10 mm, preferably in the
range 1 .mu.m to 1000 .mu.m, more preferably in the range 1 .mu.m
to 100 .mu.m.
[0027] The number average size is determined by optical
microscopy.
[0028] Further, the chemical microgel particles are constituted by
at least one chemically cross-linked hydrosoluble or
hydrodispersible polymer.
[0029] Said polymer can be obtained either directly in the
cross-linked form, for example by adding at least one cross-linking
agent to the monomers constituting the polymer, the cross-linking
agent usually being a multifunctional monomer.
[0030] Said polymer can also be obtained by carrying out a chemical
post-polymerization cross-linking step, i.e., cross-linking after
the step for polymerizing the monomer or monomers constituting said
polymer.
[0031] In an advantageous variation of the present invention, the
polymer from which the chemical microgel particles are derived is
such that the number of hydrosoluble motifs of said polymer
represents at least 50% of the number of polymer motifs, preferably
at least 80% by weight of said polymer.
[0032] The term "hydrophilic" motif means a monomer selected from
those which, once homopolymerized with a degree of polymerization
in the range 40 to 100, produces a soluble polymer under the
temperature and pH conditions of the composition. More
particularly, the temperature is in the range 15.degree. C. to
35.degree. C.
[0033] The polymers from which the chemical microgel particles are
derived are obtained at least from non ionic, ionic or potentially
ionizable (in particular under the pH conditions) hydrophilic
monomers.
[0034] More particularly, the non ionic hydrophilicity monomers are
selected from: ethylene oxide; amides of linear or branched, cyclic
or aromatic mono- or polycarboxylic acids, comprising at least one
ethylenically unsaturated bond or derivatives thereof, such as
(meth)acrylamide, N-methylol(meth)acrylamide; certain esters
deriving from (meth)acrylic acid such as 2-hydroxyethyl (meth)
acrylate; and vinyl esters that can produce polyvinyl alcohol
blocks after hydrolysis, such as vinyl acetate, vinyl
Versatate.RTM., vinyl propionate, N-vinylpyrrolidone, used alone or
as a mixture.
[0035] Regarding ionic or potentially ionic hydrophilic monomers,
anionic or potentially anionic monomers can be cited, which carry
at least one carboxylic, sulphonic, sulphuric, phosphonic,
phosphoric or sulphosuccinic function, their corresponding salts,
or their corresponding precursors.
[0036] In particular, the polymers can be obtained from at least
one monomer selected from:
[0037] linear or branched, cyclic or aromatic mono- or
poly-carboxylic acids, N-substituted derivatives of said acids, or
monoesters of poly-carboxylic acids, comprising at least one
ethylenically unsaturated bond;
[0038] linear or branched, cyclic or aromatic vinyl carboxylic
acids;
[0039] aminoacids comprising one or more ethylenically unsaturated
bonds;
[0040] alone or as a mixture, their sulphonic or phosphonic
derivatives, macromonomers deriving from said monomers, or salts or
precursors of said monomers. It should be remembered that the term
"macromonomer" designates a macromolecule carrying one or more
polymerizable functions.
[0041] Particular examples of suitable monomers are:
[0042] acrylic acid, methacrylic acid, fumaric acid, itaconic acid,
citraconic acid, maleic acid, oleic acid, linoleic acid, linolenic
acid, acrylamidoglycolic acid, 2-propene-1-sulphonic acid,
methallylsulphonic acid, styrenesulphonic acid,
.alpha.-acrylamidomethylpropanesulphonic acid, 2-sulphoethylene
methacrylate, sulphopropylacrylic acid, bis-sulphopropylacrylic
acid; bis-sulphopropylmethacrylic acid, sulphatoethyl methacrylic
acid, the phosphate monoester of hydroxyethyl methacrylic acid, and
their alkali metal salts, such as sodium or potassium salts, or
ammonium salts;
[0043] vinyl sulphonic acid, vinylbenzene sulphonic acid,
vinylphosphonic acid, vinylidene phosphoric acid, vinylbenzoic
acid, and their alkali metal salts such as sodium or potassium
salts, or ammonium salts;
[0044] N-methacryloyl alanine, N-acryloyl-hydroxy-glycine;
[0045] alone or as a mixture, as well as macromonomers deriving
from said monomers, and the salts or precursors of said
monomers.
[0046] It should be noted that the scope of the present invention
includes the use of monomers that are precursors of those just
described. In other words, said monomers have motifs which, once
incorporated into the polymer, can be transformed, in particular by
a chemical treatment such as hydrolysis, to reproduce the species
cited above.
[0047] In a second possibility, the ionic or potentially
hydrophilic monomers are selected from cationic or potentially
cationic monomers.
[0048] To this end, in a non-limiting manner, it is possible to
employ the following:
[0049] aminoalkyl (meth)acrylates, aminoalkyl
(meth)acrylamides;
[0050] monomers comprising at least one secondary, tertiary or
quaternary amine function, or a heterocyclic group containing a
nitrogen atom, vinylamine, or ethylene imine;
[0051] diallyldialkyl ammonium salts;
[0052] alone or as a mixture, as well as macromonomers deriving
from said monomers, and salts of said monomers.
[0053] Said monomers can have a counter-ion selected from halogens,
such as chlorine, sulphates, hydrosulphates, alkylsulphates,
phosphates, citrates, formats, or acetates.
[0054] Examples of cationic monomers that can form part of the
composition of the cationic blocks of the copolymer that can be
cited are:
[0055] dimethylaminoethyl(meth)acrylate,
dimethylaminopropyl(meth)acrylate- , ditertiobutyl aminoethyl
(meth)acrylate, dimethylamino methyl (meth)acrylamide,
dimethylaminopropyl(meth)acrylamide;
[0056] ethyleneimine, vinylamine, 2-vinylpyridine,
4-vinylpyridine;
[0057] trimethylammonium ethyl(meth)acrylate chloride,
trimethylammonium ethyl acrylate methyl sulphate,
benzyldimethylammonium ethyl (meth)acrylate chloride,
4-benzoylbenzyl dimethylammonium ethyl acrylate chloride
trimethylammonium ethyl (meth)acrylamido chloride,
trimethylammonium vinylbenzyl chloride;
[0058] diallyldimethyl ammonium chloride;
[0059] used alone or as a mixture, along with macromonomers
deriving from said monomers.
[0060] The scope of the present invention encompasses the use of
one or more amphoteric monomers which, depending on the pH
conditions, will provide a net positive, negative or zero charge.
Similarly, it is possible to use one or more zwitterionic type
monomers, which have a net zero charge at any pH.
[0061] Further, the polymers from which the chemical microgel
particles are derived can optionally be obtained from hydrophobic
monomers.
[0062] More particularly, the hydrophobic monomers can be selected
from:
[0063] propylene oxide, butylene oxide;
[0064] esters of linear or branched, cyclic or aromatic mono- or
poly-carboxylic acids comprising at least one ethylenically
unsaturated bond;
[0065] .alpha..beta.-ethylenically unsaturated nitriles, vinyl
ethers, vinyl esters, vinylaromatic monomers, vinyl or vinylidene
halides;
[0066] linear or branched, aromatic or non aromatic hydrocarbon
monomers comprising at least one ethylenically unsaturated
bond;
[0067] alone or as a mixture, and macromonomers deriving from said
monomers.
[0068] Particular examples of hydrophobic monomers that can be used
in preparing the polymers that can be cited are:
[0069] propylene oxide, butylene oxide;
[0070] esters of (meth)acrylic acid with an alcohol containing 1 to
12 carbon atoms, such as methyl (meth)acrylate, ethyl
(meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate,
t-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl
(meth)acrylate;
[0071] vinyl acetate, vinyl Versatate.RTM., vinyl propionate, vinyl
chloride, vinylidene chloride, methyl vinylether, ethyl
vinylether;
[0072] vinyl nitriles, more particularly including those containing
3 to 12 carbon atoms, in particular acrylonitrile and
methacrylonitrile;
[0073] styrene, .alpha.-methyl styrene, vinyl toluene, butadiene,
chloroprene;
[0074] alone or as a mixture, and macromonomers deriving from said
monomers.
[0075] The polymers from which the chemical microgel particles are
derived can be homopolymers or copolymers.
[0076] Further, they can have any structure. The copolymers may
have a random or block structure. Further, whether or not they
comprise different monomers, the polymers can be linear, branched,
comb-like in structure or star type in structure.
[0077] The choice of the nature of the monomers detailed above and
their respective proportions can readily be determined by the
skilled person to obtain a hydrosoluble or hydrodispersible
chemical microgel as a final product.
[0078] Production of the chemical microgel particles will now be
described.
[0079] In a first implementation, the chemical microgel particles
are obtained by carrying out the following steps:
[0080] a) preparing a chemical gel in an aqueous phase by
polymerizing the desired monomer or monomers and a crosslinking
agent, or by chemical post-polymerization cross-linking of a
polymer;
[0081] b) grinding the resulting gel to obtain chemical microgel
particles.
[0082] Note that the polymers from which the chemical microgel
particles are derived are advantageously obtained by using radical
polymerization, although other types of polymerization are
perfectly possible, such as anionic or cationic polymerization.
[0083] It is also possible to employ, depending on the monomers
used, group transfer polymerization or ring opening polymerization
(especially when polymerizing from a N-carboxy anhydride ring).
[0084] Preferably, the polymers are obtained using at least one
living radical polymerization step.
[0085] Examples of living or controlled polymerization processes
that can be referred to are:
[0086] the processes described in International applications
WO-A-98/58974, WO-A-00/75207 and WO-A-01/42312, which employ
radical polymerization controlled by xanthate type control
agents;
[0087] a radical polymerization process controlled by dithioester
type control agents as described in WO-A-98/01478;
[0088] the process described in WO-A-99/03894, which employs
polymerization in the presence of nitroxide precursors;
[0089] the radical polymerization process controlled by control
agents of the dithiocarbamate type as described in
WO-A-99/31144;
[0090] the radical polymerization process controlled by control
agents of the dithiocarbazate type as described in
WO-A-02/26836;
[0091] the radical polymerization process controlled by control
agents of the dithiophosphoroester type described in
WO-A-02/10223;
[0092] the process in application WO-A-96/30421, which employs atom
transfer radical polymerization;
[0093] the radical polymerization process controlled by Iniferter
type control agents as described by Otu et al, Makromol. Chem.
Rapid. Commun. 3, 127 (1982);
[0094] the radical polymerization process controlled by
degenerative iodine transfer, as described by Tatemoto et al, Jap.
50, 127, 991 (1975), Daikin Kogyo Co Ltd Japan and Matyjaszewski et
al, Macromolecules, 28, 2093 (1995);
[0095] the radical polymerization process controlled by
tetraphenylethane derivatives, disclosed by D Braun et al in
Macromol. Symp. 111, 63 (1996); or
[0096] the radical polymerization process controlled by
organocobalt complexes as described by Wayland et al in J. Am Chem.
Soc. 116, 7973 (1994).
[0097] Preferably, when the polymers from which the chemical
microgel particles are derived have a block structure, the
polymerization reaction carried out to obtain them is conducted in
the presence of at least one control agent especially of the
xanthate, dithiocarbamate or dithioester type.
[0098] When the polymers do not have such a structure, conventional
radical polymerization is suitable (i.e., without a control
agent).
[0099] In a first variation of this implementation, the polymer
from which the chemical microgel particles are derived is obtained
by carrying out polymerization in the aqueous phase of the desired
monomers and at least one cross-linking agent. In this case,
polymerization and cross-linking are carried out
simultaneously.
[0100] The monomers listed above when describing the polymers are
employed.
[0101] The cross-linking monomers that can be used have at least
two reactive functions in the selected polymerization mode. In the
case of radical polymerization, at least one monomer comprising at
least two ethylenically unsaturated bonds and at most 10
unsaturated bonds and known to be radically reactive is used.
[0102] Preferably, said monomers have two ethylenically unsaturated
bonds. The following can in particular be cited: acrylic,
methacrylic, acrylamido, methacrylamido, vinyl ester, vinyl ether,
diene, styrene, alpha-methyl styrene and allyl derivatives.
[0103] Monomers belonging to those families are: vinyl
methacrylate, methacrylic acid anhydride, allyl methacrylate,
ethylene glycol dimethacrylate, phenylene dimethacrylate,
diethylene glycol dimethacrylate, triethylene glycol
dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene
200 dimethacylate, polyethylene glycol 400 dimethacylate,
butanediol 1,3-dimethacrylate, butanediol 1.4-dimethacrylate,
hexanediol 1,6-dimethacrylate, dodecanediol 1,12-dimethacrylate,
glycerol 11.3-dimethacrylate, diurethane dimethacrylate,
trimethylolpropane trimethacrylate. Particular members of the
multifunctional acrylate family that can be cited are vinyl
acrylate, bisphenol A epoxy diacrylate, dipropylene glycol
diacrylate, tripropyleneglycol diacrylate, polyethylene glycol 600
diacrylate, ethylene glycol diacrylate, diethylene glycol
diacrylate, triethylene glycol diacrylate, tetraethylene glycol
diacrylate, ethoxylated neopentyl glycol diacrylate, butanediol
diacrylate, hexanediol diacrylate, aliphatic urethane diacrylate,
trimethylolpropane triacrylate, ethoxylated trimethylolpropane
triacrylate, propoxylated trimethylolpropane triacrylate,
propoxylated glycerol triacrylate, aliphatic urethane triacrylate,
trimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate.
Vinyl ethers that can be cited are vinyl crotonate, diethylene
glycol divinyl ether, 1,4-butanediol divinyl ether, triethylene
glycol divinyl ether. The following allyl derivatives can be cited:
diallyl phthalate, diallyldimethyl ammonium chloride, diallyl
malleate, sodium diallyloxyacetate, diallylphenylphosphine,
diallylpyrocarbonate, diallyl succinate, N,N'-diallyltartardiamide,
N,N-diallyl-2,2,2-trifluoroacetamide, the allyl ester of
diallyloxyacetic acid, 1,3-diallyl urea, triallylamine, triallyl
trimesate, triallyl cyanurate, triallyl trimellitate,
triallyl-1,3,5-triazine-2,4,6-(1H,3H,5H- )-trione. Acrylamido
derivatives that can in particular be cited are
N,N'methylenebisacrylamide, N,N'-methylenebismethacrylamide,
glyoxal bisacrylamide, diacrylamdoacetic acid. Styrene derivatives
that can be cited include divinylbenzene and
13-diisopropenylbenzene. Diene monomers that can be cited are
butadiene, chloroprene and isoprene.
[0104] Preferred cross-linking monomers are
N,N'-methylenebisacrylamide, divinylbenzene and ethylene glycol
diacrylate.
[0105] Further, the quantity of cross-linking agent can readily be
determined by the skilled person depending on the desired degree of
cross-linking and such that the chemical microgel particles to be
obtained finally are hydrosoluble or hydrodispersible, as defined
above.
[0106] The polymerization reaction is carried out in the presence
of at least one source of free radicals. This radical
polymerization initiator can be selected from initiators
conventionally used in radical polymerization, such as:
[0107] peroxides of hydrogen, such as tertiary butyl hydroperoxide,
cumene hydroperoxide, t-butyl-peroxyacetate,
t-butyl-peroxybenzoate, t-butylperoxyoctoate,
t-butylperoxyneodecanoate, t-butylperoxyisobutarate- , lauroyl
peroxide, t-amylperoxypival, t-butylperoxypivalate, dicumyl
peroxide, benzoyl peroxide, potassium persulphate and ammonium
persulphate;
[0108] azo compounds, such as: 2,2-azobis(isobutyronitrile),
2,2'-azobis(2-butanenitrile), 4,4'-azobis(4-pentanoic acid),
1,1'-azobis(cyclohexane-carbonitrile),
2-(t-butylazo)-2-cyanopropane, 2,2'-azobis
[2-methyl-N-(1,1)-bis(hydroxymethyl)-2-hydroxyethyl]propionam- ide,
2,2'-azobis(2-methyl-N-hydroxyethyl]-propionamide,
2,2'-azobis(N,N'-dimethylene isobutyramidine) dichloride,
2,2'-azobis(2-amidinopropane) dichloride,
2,2'-azobis(N,N'dimethyleneisob- utyramide),
2,2'-azobis(2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]-
propionamide), 2,2'-azobis(2-methyl-N-[1,1-bis
(hydroxymethyl)ethyl]propio- namide),
2,2'-azobis[2-methyl-N-(2-hydroxyethyl) propionamide],
2,2'-azobis(isobutyramide)dihydrate;
[0109] redox systems comprising combinations such as mixtures of
peroxides of hydrogen, and analogues with one or more iron salts,
titanous salts, etc. and reducing sugars; alkali metal or ammonium
persulphates, perborates or perchlorates in association with an
alkali metal bisulphite and reducing sugars; alkali metal
persulphate in association with an arylphosphinic acid and reducing
sugars.
[0110] Normally, the quantity of initiator to be used is determined
so that the quantity of radicals created is at most 50 mole %,
preferably at most 20 mole % with respect to the quantity of
polymer or control agent.
[0111] The temperature can be between ambient temperature and
150.degree. C., depending on the nature of the monomers used.
[0112] Polymerization is advantageously carried out in solution in
water.
[0113] In a second variation of this first implementation, the
polymer from which the chemical microgel particles is derived is
prepared by carrying out aqueous phase polymerization of the
desired monomer or monomers followed by a step for cross-linking
said polymer (post-polymerization cross-linking).
[0114] The cross-linking agents cited above can be used during this
step.
[0115] The conditions for carrying out the cross-linking are of the
same type as those for the polymerization reaction, with the
exception that no control agent is introduced.
[0116] Thus, cross-linking is carried out in the presence of at
least one initiator, in an amount such that the quantity of
radicals created is at most 50 mole %, preferably at most 20 mole %
with respect to the quantity of polymer.
[0117] It should be noted that depending on the nature of the
monomers forming the polymer, cross-linking can consist of reacting
the polymer functions together. As an example, it may concern
esterification or transesterification reactions.
[0118] In this case, catalysts that are particular to those
reactions, such as acids or bases, can be added to the polymer.
[0119] In a further possibility, polymer cross-linking can be
carried out using multifunctional non-polymerizable compounds
carrying at least one chemical function that is an antagonist to
that/those carried by the polymer to be cross-linked. As an
example, it is possible to use a di-iodine compound to cross-link a
polymer carrying at least one poly(2-dimethylaminoethyl acrylate)
block, or glutaraldehyde to cross-link a polyvinyl type alcohol,
etc.
[0120] The polymer is separated from the reaction mixture in
conventional manner, for example by precipitation from a
non-solvent.
[0121] Once the chemically cross-linked polymer has been obtained,
the latter is ground.
[0122] This operation is carried out conventionally. Conventional
mills can be used, and also ultrasound.
[0123] It is generally carried out with a polymer dispersed in a
non-solvent. This operation is carried out for a period that is
sufficient to obtain a number average particle size in the range
0.3 .mu.m to 10 mm, preferably in the range 1 .mu.m to 1000 .mu.m,
more preferably in the range 1 .mu.m to 100 .mu.m.
[0124] In a second implementation, the chemical microgel particles
are obtained by carrying out polymerization of the desired monomers
and the cross-linking agent in micro-reactors and/or with stirring
and/or in the presence of at least one limiting agent, or by
chemical post-polymerization cross-linking in micro-reactors and/or
with stirring, of a polymer obtained by polymerization of the
desired monomers or monomers.
[0125] It should be noted that said polymer from which the chemical
microgel particles are derived may or may not be obtained by
carrying out the polymerization in micro-reactors and/or with
stirring.
[0126] The information given above regarding the nature of the
monomers, the cross-linking agents and the presence or absence of
the control agent is also valid as regards this second
implementation: the difference is essentially the manner in which
the polymerization and possibly cross-linking reactions are carried
out.
[0127] Regarding the limiting agent, this latter can be selected
from radical transfer agents, for example compounds of the thiol
type (see Sherrington, Polymer 41 (2000)) or from control agents,
for example of the nitroxide type (see D H Solomon et al, Macromol.
Rapid Commun. 18, 755 (1997) and Polymer 42, 5987 (2001)). Using
such agents prevents macrogel formation.
[0128] This second implementation aims to provide access to
chemical microgel particles without having to carry out a polymer
grinding step. To achieve this, polymerization is carried out in
micro-reactors either with stirring or in the presence of a
limiting agent, or by a combination of these possibilities.
[0129] More particularly, micro-reactors are droplets of an
emulsion, which in the present case is a reverse emulsion
(water-in-oil).
[0130] The skilled person can readily carry out emulsion
polymerization reactions.
[0131] More particularly, the organic phase is composed of an
organic solvent that is not miscible with water and is inert under
the reaction conditions. Examples that can be cited are hexane,
heptane, isoparaffin cuts, etc.
[0132] Further, the organic phase of the emulsion further comprises
at least one surfactant.
[0133] Preferably, the surfactant is selected from those that are
at least partially soluble in the organic phase of the
emulsion.
[0134] Advantageously, particular surfactants that can be employed
in this implementation are selected from non ionic surfactants with
a low HLB (more particularly 8 or less).
[0135] The following are suitable: alkoxylated fatty alcohols,
alkoxylated triglycerides, alkoxylated fatty acids, sorbitan
esters, which may have been alkoxylated, alkoxylated fatty amines;
the number of alkoxylated motifs (oxyethylenated, oxypropylenated,
oxybutylenated) is such that the HLB is 8 or less.
[0136] It should be noted that the polymerization reaction can also
be carried out using an amphiphilic polymer to stabilize the
reverse emulsion, used alone or as a mixture with one or more of
said surfactants.
[0137] Examples of said polymers that can be cited are
polyhydroxystearate triblock polymers-polyethylene
glycol-polyhydroxystearate (products from ICI's Arlacel range, for
example).
[0138] In a particularly advantageous implementation, the reverse
emulsion comprises an amphiphilic polymer or a mixture of a
plurality thereof.
[0139] The total quantity of surfactant and/or amphiphilic polymer
preferably represents 2% to 10% of the oily phase weight.
[0140] When polymerization is carried out with stirring, the latter
must be sufficient to shear the reaction mixture and ensure that
the polymer obtained is of appropriate size.
[0141] It should be noted that a combination of these two
possibilities is possible.
[0142] Finally, the scope of the present invention encompasses
carrying out a grinding step on the particles obtained at the end
of said steps.
[0143] The second constituent of the composition of the invention
is the bridging polymer. This is a hydrosoluble or hydrodispersible
polymer with a chemical nature that differs from that of the
chemical microgel particles described above.
[0144] It should be noted that the bridging polymer is considered
to have a different chemical composition (nature) from that of the
microgel particles if the overall compositions of the polymers are
different either as regards the nature of the repeating units or
the respective proportions of the repeating units.
[0145] Further, the bridging polymer and the chemical microgel
particles are associated in an at least partially reversible
manner. In fact, the composition comprising the bridging polymer
and the microgel particles has rheological characteristics such
that the difference between the initial viscosity and the viscosity
after shear treatment for 5 minutes at 100 s.sup.-1 measured after
leaving for 24 hours is 50% or less, preferably 20% or less of the
initial viscosity.
[0146] As indicated above, the quantity of bridging polymer is such
that the viscosity of the composition is at least three times that
of an aqueous solution of chemical microgel particles and that of
an aqueous solution of the bridging polymer under the same
conditions (concentration, temperature). Preferably, the viscosity
of the composition is at least ten times that of an aqueous
solution of chemical microgel particles and that of an aqueous
solution of bridging polymer under the same conditions.
[0147] More particularly, the bridging polymer is constituted by at
least one polymer with a mass average molar mass that is in the
range 10.sup.3 to 5.times.10.sup.7 g/mol, more particularly in the
range 10.sup.4 to 10.sup.7 g/mol, preferably in the range
5.times.10.sup.5 to 5.times.10.sup.6 g/mol. Said mass average molar
masses are determined using the MALLS (multi-angle light
scattering) method coupled with gel permeation chromatography.
[0148] In accordance with a preferred characteristic of the
invention, the bridging polymer used has a linear structure,
optionally comprising pendent side chains (grafts).
[0149] In a first variation of the invention, the bridging polymer
is obtained at least starting from non ionic, ionic or potentially
ionizable and optionally hydrophobic monomers.
[0150] Regarding the hydrophilic and hydrophobic monomers mentioned
above, reference can be made to the lists relating to each of said
monomers, given as part of the description regarding the polymers
from which chemical microgel particles can be obtained.
[0151] Reference can also be made to the various methods for
preparing the polymers, with the exception that the bridging
polymers are not cross-linked species. Preferably, the
cross-linking agent is employed during or after producing said
polymers.
[0152] The choice of bridging polymer is made as a function of the
nature of the cross-linked polymer constituting the chemical
microgel particles, in order to produce interactions between the
two compounds, namely the bridging polymer and the chemical
microgel particles.
[0153] As an example, when the chemical microgel particles and the
bridging polymer are to be associated by means of electrostatic
type interactions, the latter are selected so that the net overall
charge of the chemical microgel particles is opposite to that of
the net overall charge of the bridging polymer. More precisely,
when the chemical microgel particles include anionic motifs, the
bridging polymer is selected so that certain of its repeating units
include cationic or potentially cationic charges (for example under
the pH use conditions of the composition).
[0154] Advantageously, the bridging polymer is such that it has a
degree of charged monomer polymerization in the range 5 to 10.
[0155] Preferably, in the case of this type of interaction, at
least 50 number %, preferably at least 80 number % of the monomers
constituting the polymeric chain of the bridging polymer and the
chemical microgel particles have no ionic charge.
[0156] In a further possibility, the chemical microgel particles
and the bridging polymer are associated by means of
hydrophobic-hydrophobic type interactions. In this case, the
microgel particles and the bridging polymer comprise motifs that
can associate together in the aqueous phase by means of said
bonds.
[0157] An example of said type of interaction that can be cited is
the association of microgel particles comprising long alkyl chains
(for example C.sub.8 to C.sub.22 or more) with a C.sub.6 to
C.sub.22 alkyl acrylate type bridging polymer.
[0158] In a final possibility, the chemical microgel particles and
the bridging polymer are associated by means of hydrogen bond type
interactions. In this variation, the chemical microgel particles
and the bridging polymer comprise motifs that can associate
together in an aqueous phase via such bonds (for example,
carboxylic and/or amide motifs and ether and/or alcohol and/or
amine motifs).
[0159] In this case, the bridging polymer and the chemical microgel
particles comprise carboxylic acid, alcohol, ether, or amide type
functions, for example.
[0160] In a second variations of the invention, the bridging
polymer comprises at least one polymer selected from biopolymers
that may or may not have been chemically modified.
[0161] In this variation, the biopolymers are selected from
polysaccharides such as galactomannans, glucomannans,
succinoglycans, xanthan gum, cellulose, alginates, gelatin, which
may or may not have been chemically modified.
[0162] The choice of biopolymer (non ionic, hydrophobic, anionic,
cationic, . . . ) will be made as a function of the nature of the
chemical microgel particles, in order to obtain interactions
between the particles and the bridging polymer of the type listed
above, namely electrostatic interactions, hydrophobic-hydrophobic
interactions, or hydrogen bonds.
[0163] The composition of the invention can be obtained by carrying
out the following steps:
[0164] a) preparing a chemical gel in an aqueous phase by
polymerizing the desired monomer or monomers and a crosslinking
agent, or by chemical post-polymerization cross-linking of a
polymer;
[0165] b) grinding the resulting gel to obtain chemical microgel
particles;
[0166] c) bringing said chemical microgel particles into contact
with at least one bridging polymer in an aqueous phase.
[0167] In a further variation, the composition is obtained by
carrying out the following steps:
[0168] a) preparing particles of chemical microgel by polymerizing
the desired monomer or monomers and a cross-linking agent in
micro-reactors and/or with stirring and/or in the presence of at
least one limiting agent, or by chemical post-polymerization
cross-linking of a polymer in micro-reactors and/or with
stirring;
[0169] b) bringing said chemical microgel particles into contact
with at least one bridging polymer in an aqueous phase.
[0170] For each of these two possibilities, the first two steps
have already been described above in the context of the polymers
from which the chemical microgel particles are obtained.
[0171] The last step is carried out simply by mixing the bridging
polymer and the chemical microgel particles.
[0172] The invention also concerns the use of the composition
described above in the fields of oil or gas field working,
detergents, cosmetics, and metal treatment (transformation,
deformation).
[0173] In a final aspect, the invention concerns formulations
comprising said composition; the formulations being intended for
the fields of oil or gas field working, detergents or
cosmetics.
[0174] Non limiting examples of the invention will now be
given.
EXAMPLE 1
Synthesis of PAA/PHEA microgel
Step 1: Synthesis of a PAA-b-PHEA Block Copolymer (polyacrylic
acid-b-polyhydroxyethyl acrylate) 5000-b-30000
[0175] Synthesis Of First Block
[0176] 30 g of acrylic acid (AA), 1.255 g of
O-ethyl-S-(1-methoxycarbonyl)- ethylenyl) xanthate
(CH.sub.3CHCO.sub.2CH.sub.3)S(C.dbd.S)OEt, 0.147 g of AIBN and 125
ml of acetone were placed in a three-necked flask provided with a
coolant, a magnetic stirrer and a heating bath. The medium was
heated to 70.degree. C. for 20 h. The solvent was evaporated off
under vacuum and vacuum dried to constant mass.
[0177] The number average molar mass (Mn) was measured by steric
exclusion chromatography (CES) using linear PAA standards for the
calibration.
[0178] Mn=4300 g/mol
[0179] Synthesis of Diblock
[0180] 10 g of polyacrylic acid (PAA) with a xanthate terminus
described above, 74 g of distilled water and 148 g of acetone were
placed in a three-necked flask provided with a coolant, a magnetic
stirrer and a heating bath.
[0181] The medium was heated to 70.degree. C. over 30 minutes.
[0182] At 70.degree. C., 69.8 g of hydroxyethyl acrylate (HEA was
continuously added over 2 h45 and 0.076 g of azoisobutyronitrile
(AIBN) was added in one shot. Two portions of AIBN each of 0.076 g
was added two hours and four hours after starting to introduce the
monomer. Heating and stirring were maintained for 16 h.
[0183] The final dry extract was 26.4% by weight.
[0184] Step 2: Cross-Linking of Block Copolymer
[0185] The above solution of copolymer was left in the oven at
40.degree. C. for 30 days. Light diffusion then conventional
microscopy were used to monitor the appearance of the
microgels.
[0186] Production of GEL
[0187] An aqueous solution A containing 3.2% by weight of the above
microgel was prepared at a pH of 7 (adjustment using an aqueous
solution of molar sodium hydroxide).
[0188] An aqueous solution B was prepared containing 0.82% of a
cationic polymer, Glokill PQ (sold by RHODIA CHIMIE). Solution B
was also brought to a pH of 7 using sodium hydroxide.
[0189] The aqueous formulation C was then prepared by mixing an
identical mass of A and B.
[0190] Formulae A' and B' were also prepared by respectively
diluting solutions A and B with water, twice (pH constant=7).
1 Formulations Viscosity* (Pa .multidot. s) A' <0.0 B' <0.1 C
10 *viscosity measured using a Carrimed type viscosimeter with a
cone-plate geometry; the measurements were made at 25.degree. C. at
a shear rate of 1 s.sup.-1.
EXAMPLE 2
Synthesis of PAA/Pam Microgel
Step 1: Synthesis of a PAA-b-Pam Block Copolymer (polyacrylic
acid-b-polyacrylamide) 5000-b-60000
[0191] Synthesis of First Block
[0192] 7.7 g of acrylic acid (AA), 0.32 g of
O-ethyl-S-(1-methoxycarbonyl)- ethylenyl) xanthate
(CH.sub.3CHCO.sub.2CH.sub.3)S(C.dbd.S)OEt, 0.22 g of
4,4'-azobis(4-cyanovaleric acid), 2.5 g of isopropanol and 16.7 g
of water were placed in a three-necked flask provided with a
coolant, a magnetic stirrer and a heating bath. The medium was
limited to 70.degree. C. for 6 h.
[0193] A sample was removed and the number average molar mass (Mn)
was measured by steric exclusion chromatography (CES) using linear
PAA standards for the calibration.
[0194] Mn=4500 g/mol
[0195] Synthesis of Diblock
[0196] 92.3 g of acrylamide, 0.21 g of 4,4'-azobis(4-cyanovaleric
acid) and 215.8 g of water were added to the polymer from step 1,
kept at 70.degree. C. The mixture was heated for 6 hours.
[0197] A sample was removed and its mass average molecular mass
(Mn) was measured: Mn=49000.
[0198] Step 2: Synthesis of Microgel Based on PAA and Pam
[0199] 10 g of diblock copolymer from step 1 was diluted to 12% in
water. 1.18 g of N,N-methylenebis acrylamide and 20 mg of
4,4'-azobis(4-cyanovaleric acid) were then added to the diblock
solution. The mixture was then heated to 70.degree. C. for 5
hours.
[0200] The prepared product formed a clear solution in water. It
could not be filtered using a 0.45 .mu.m GPC filter, proof of the
formation of a microgel.
[0201] Production of GEL
[0202] An aqueous solution A containing 6% by weight of the above
microgel was prepared at a pH of 7 (adjustment using an aqueous
solution of molar sodium hydroxide).
[0203] An aqueous solution B was prepared containing 1.6% of a
cationic polymer, Glokill PQ (sold by RHODIA CHIMIE). Solution B
was also brought to a pH of 7 using sodium hydroxide.
[0204] The aqueous formulation C was then prepared by mixing an
identical mass of A and B.
[0205] Formulae A' and B' were also prepared by respectively
diluting solutions A and B with water, twice (pH constant=7).
2 Formulations Viscosity* (Pa .multidot. s) A' <3 B' <1 C
>10 *viscosity measured using a Carrimed type viscosimeter with
a cone-plate geometry; the measurements were made at 25.degree. C.
at a shear rate of 1 s.sup.-1.
* * * * *