Gopolymers with gem-biphosphonate groups
The present invention relates to copolymers with gem-biphosphonate groups, to a
method for their preparation and to their use as fluidifiers of suspensions of mineral
particles, notably compositions of cements and plaster formulations'
[State of the art]
Generally, admixtures are added to cement compositions for improving their
properties. Rheological properties and their change over time, related to their workability'
are among the fundamental properties of cement compositions'
Fluidifiers or plasticizers are in particular used, which have the effect of fluidifying
cement compositions and thus allow a reduction in the amount of water added, this is why
they are also designated as water reducing agents. The composition then has a higher
density and results in a material having a higher mechanical strength'
1s certain soluble polymers called superplasticizers give the possibility of further
reducingtheamountofwater'Superplasticizersofthetypeof
polyalkoxylatedpolycarboxylic acids (PCPs)are notably known'
DocumentFR2Eg242odescribessuperplasticizers
polyoxyalkylate groups for fluidifying suspensions of mineral
phosphonate groups are amino-bisalkylenephosphonic groups
(A):
E
I
-L-X-IN (A l-POsFt I 2)lv
(A)
whereinLrepresentsagroupforbindingtothemainchainandXisanalkyleneor
oxyalkylene group. Phosphonate monomers may notably be obtained by diphosphonation
accordingtotheconditionsoftheMoEDRlTzER-lMNlreactionbyreactionofanamine
with formaldehyde and phosphorous acid'
lnordertoaccessthesestructures,chemicalmodificationofapolymerby
post-grafting is also proposed. This method includes two steps' i'e' the copolymerization
of an unsaturated carboxylic acid with a polyethoxylated (meth)acrylic ester followed by
graftingofaphosphonateamineoralcoholsynthonor,alternatively,polymerizationofthe
unsaturated carboxylic acid and subsequent esterification with polyalkoxylate compounds
followed by grafting of a phosphonatesynthon'
[Technical Problem]
The object of the invention is to provide novel modified copolymers useful as
admixtures for suspensions of mineral particles'
Another object is to provide a method for preparing these copolymers which is
simple and economical and in particular does not require the use of formaldehyde'
still another object is to provideadmixtures for suspensions of mineral particles
having substantialwater reducing power, good maintenance of rheology, low sensitivity to
alkaline sulfates and to clays and good robustness towards different cements'
[Summary of the invention]
The objects mentioned above are achieved according to the invention with
copolymers including gem-biphosphonic groups'
Thus, according to the invention a copolymer is provided, comprising a main
hydrocarbonchainandsidegroups,whereinthesidegroupscomprisecarboxylicgroups'
15 polyoxyalkylate groups and gem-biphosphonate groups'
According to a second aspect, the invention is directed to a method for preparing
these copolymers comprising the steps:
(i)polymerizingamonomerbearingacarboxylicgroup,optionallyinthe
presence of a monomer bearing a polyoxyalkylate group; and
(ii)graftingtheobtainedpolymerwithareactivegem-biphosphonate
comPound'
The gem-bisphosphonate copolymer thereby obtained is advanta$eously
formulated before use, preferably as a solution, notably as an aqueous solution' The
formulation may also include the customary additives in this field'
Accordingtoanotheraspect,theinventionisthereforedirectedtoanadmixturefor
suspensions of mineral particles comprising the copolymer according to the invention as a
solutioninasuitablesolventorinadryform,notablyasapowder.
Moreover, the invention according to another aspect is directed to the use of the
copolymeraccordingtotheinventionforfluidifyingsuspensionsofmineralparticlesand/or
formaintainingtheworkabilityofhydraulicbinders.ltisalsodirectedtotheuseofthe
copolymeraccordingtotheinventionforreducingthesensitivityofhydrauliccompositions
to claYs and alkaline sulfates'
Finally,accordingtoalastaspect,theinventionisdirectedtoacompositionof
mineralparticlescomprisingthecopolymeraccordingtotheinvention.
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IDefinitions]
Within the scope of the present discussion, by the term of < suspension of mineral
particles ) or ( hydraulic composition > is meant any binder with hydraulic setting, i.e.
notably in addition to cements such as Portland cements, aluminous cements, mortars
further comprising fine granulates, concretes further comprising coarse granulates or
further anhydrous calcium sulfate or semi-hydrates thereof. The term also encompasses
inert mineral fillers such as calcium sulfate dihydrates as well as calcium carbonate, silica,
titanium hydroxide and clay compounds.
By the term of < hydrocarbon chain > is meant an aliphatic, saturated or
unsaturated, aromatic, arylalkyl or alkylaryl, linear or branched group, including carbon
and hydrogen atoms, optionally interrupted and/or terminated with one or several
hetero-atoms such as S, O, N, P.
The term of < gem-bisphosphonate group > is meant to refer to groups including
two phosphonate groups bound to a Same carbon atom' These groups therefore have a
P-C-P bond.
By the term of < alkyl group > is meant a linear, branched or cyclic alkyl group'
ln the same way, by the term of < alkylene group > is meant a linear or cyclic
alkylene grouP.
[Detailed description of the invention]
The copolymers according to the invention are comb copolymers including q main
hydrocarbon chain on the one hand and side groups on the other hand' They are further
characterized by the presence of carboxylic groups' polyoxyalkyl groups and
gem-bisphosphonate groups as side groups'
The simultaneous presence of these three types of groups gives the copolymer
interesting properties aS an admixture, notably of a superplasticizer' for suspensions of
mineral particles.
[CopolYmers]
ln their widest definition, the copolymers proposed according to the invention are
modified polymers of the PCP type including gem-bisphosphonate groups'
The polymer is of the comb type, including a main chain and side groups' The
main hydrocarbon chain preferably does not comprise any hetero-atoms' A linear main
chain is more Preferred.
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According to the invention, the copolymer moreover comprises side groups
including carboxylic groups and polyoxyalkylate groups, and further gem-bisphosphonate
groups. Advantageously, the polyoxyalkylate side groups are bound to the main chain
through an ester, ether or amide bond.
Preferably, the gem-bisphosphonate groups fit the formula (lA) below :
o
Il lI/ O-R1
-t_x_g7r P-o-R1 I ,,o_R1 R2 fi-o-*,, o (A)
wherein:
Lrepresentsagroupforbindingtothemainchain,inparticularabond,anoxygen
atom,agroup-N&-,(&beinghydrogenoraCt-Cealkylgroup),oranalkylenegroup,
preferably, L is an oxygen atom or a groue -NRr-i
X is a spacer group, in particular a cr-czoalkylene group optionally substituted or a
chain of groups of formula -(QO).- in which Q represents an alkylene group with 2 to 4
carbon atoms or a mixture of alkylene groups, n being an integer varying from 1 to 500,
preferably, X is a Cr-Cealkylene group;
R1 is, independenfly of each other, a monovalent group, notably a hydrogen, a
cr-co alkyl group or a group of formula -(QO)nR5 wherein Q represents an alkylene group
with 2 to 4 carbon atoms or a mixture of these alkylene groups, n is an integer varying
from 1 to 500 and R5 is a hydrogen or a Cr-Cs alkyl, or R1 is a cation' notably an alkali
metal, alkaline earth metal or ammonium cation; and
R2 is a monovalent group, notably a hydrogen atom or a hydroxyl group or a
Cr-Cro alkyl group, preferably, R2 is a hydroxyl group'
The group L is most often bound to a carboxylic group of the copolymer and
consequently the oxygen atom forms therewith an ester function and the amine groups'
an amide function.
The proportion of the respective gem-bisphosphonate groups in the copolymer
according to the invention may widely vary. ln particular, the copolymers comprise 0'1 to
60%, in particular 1 to 40% and most particularly 2 to lOo/o in number of
gem-bisPhosPhonate side g rouPs'
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5
The copolymer also includes as side groups, polyoxyalkylate groups. These
polyoxyalkylate groups may be bound to the main chain directly or via groups formed with
the present carboxylic functions, notably through an ester or amide bond'
They may also be integrated into the gem-bisphosphonate groups, notably of
formula (l).
The polyoxyalkylate groups may notably be of the formula (ll) below:
-R"-Z-A (ll)
wherein:
R" is a cr-crzalkylene group or a c=o group or is further absent; and
Z is an oxygen atom or a group N-R4, R4being hydrogen or a Cr-Co alkyl group;
and
A is a group of formula -(QO),-OR3 wherein:
Q represents an alkylene group with 24 carbon atoms or a mixture of these
alkYlene grouPS;
n is an integer varying froq 1 to 500; and
R3 represents a hydrogen atom or a CrCe alkyl, aryl, alkyaryl or arylalkyl
group, PreferablY a methYl'
The copolymer generally comprises 0'001 to 80o/o in number, in particular' 10 to
50% in number of polyoxyalkylate groups'
According to the invention, the copolymer moreover includes carboxylic groups'
Preferably, the carboxylic groups fit the formula (lll) below:
-c(o)-o-Rd (lll)
wherein:
R6repreSentsHoraCr-Cr2alkyl,aryl,alkylarylorarylalkylgrouporanalkali
metal, alkaline earth metal or ammonium cation'
The proportion of the carboxylic groups in the copolymer may vary from 0 to 90%'
in particular from 40 to 80% in number of carboxylic groups'
Thesecarboxylicgroupsmaybeintheformofanon-dissociatedacid.Mostoften,
they will however be at least partly or totally neutralized, esterified or amidified'
The copolymer according to the invention generally has an average molar mass
comprised between 1,000 and 220,000 (Mw), preferably between 10'000 and 110'000
(Mw) as determined by sEC (< size exclusion chromatography >) in equivalent of
standard PolYoxYethYlene.
The polymolecularity index lp is preferably comprised between 1 and 5' preferably
between 1.5 and 3.
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[Method for preparing the copolymers according to the invention]
According to a second aspect, the invention proposes a method for preparing the
copolymer grafted with gem-bisphosphonate groups as described below.
Several types of reaction may be suitable for preparing the copolymer according to
the invention.
Notably, it may be prepared by copolymerization of suitable monomers or by
modifying a polymer by grafting side groups. The latter method is also called post-grafting'
Thus, according to an embodiment, the described copolymer is prepared by bulk
or solution copotymerization, in the presence of a suitable catalyst, of monomers which
may polymerize bearing the sought groups respectively. lt is thus possible to polymerize a
mixture comprising a monomer bearing a gem-bisphosophonate group' a monomer
bearing a carboxylic group and optionally a monomer bearing a polyoxyalkylate group'
A suitable monomer bearing the gem-bisphosphonate group is notably a
(meth)acrylate or (meth)acrylamide bearing a gem-bisphosphonate unit' for example'
obtained by reaction of a compound gf formula of (l) with (meth)acryloyl chloride or
(meth)acrylic anhYdride.
A monomer bearing a suitable polyoxyalkylate group is notably
(meth)oxypolyethylene glycol, (meth)acrylate or (meth)acrylamide'
The monomer bearing a carboxylic group may in particular be selected from
unsaturated carboxylic acids such as acrylic acid, methacrylic acid' maleic acid' fumaric
acid, itaconic acid and their substituted derivatives, or further a compound which may
generate unsaturated carboxylic functions in situ,like maleic anhydride' '
The copolymer according to the invention may then be obtained by
copolymerization of these monomers, notably via a radical route under the usual
conditions in the presence of a suitable initiator'
Accordingtoanotherembodiment,thepolymerispreparedwithaso.called method. In this method, a polymer comprising a hydrocarbon chain and the
carboxylic side groups and optionally polyalkoxylate side groups is modified by grafting
gem-bisPhosPhonate grouPS.
Graftingispreferablycarriedgutbyreactingcarboxylicgroupswitha
gem-bisphosphonate compound bearing a reactive function' notably a primary or
secondary amine or alcohol group'
Also,accordingtoasecondaspect,theinventionisdirectedtoamethodfor
preparing the copolymer described above comprising the steps:
(i)polymerizingamonomerbearingacarboxylicgroup,optionallyinthe
presence of a monomer bearing a polyoxyalkylate group; and
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grafting the obtained polymer with a reactive gem-bisphosphonate
compound.
Alternatively, it is possible to polymerize the carboxylic monomer and then esterify
to the desired degree the carboxylic groups with polyoxyalkylate compounds, as this is for
example described in patent application FR 2 776 285, before grafting the obtained
product with a reactive gem-bisphosphonate compound'
Preferably, the reactive gem-bisphosphonate compound is a gem-bisphosphonate
alcohol or amine, amines being preferred because of their befter reactivity at a low
temperature.
Advantageously, the reactive gem-bisphosphonate compound is of the following
formula (l):
!,,o*,
Y-x,<:-'fr,
R2 -o5-o'R(r" )
wherein:
Yisafunctionalgroupwhichmayreactwiththecarboxylicfunctionsofthe
lSpolymer,notablyahydroxyl,primaryorsecondaryamine,isocyanateorthiolgroup;
XisaSpacergroup,inparticularaCr.Czoalkylenegroupoptionallysubstitutedora
chain of groups of formula -(ao).- in which Q represents an alkylene group with 2 to 4
carbonatomsoramixtureofthesealkylenegroups'preferably'Xisacr-coalkylene
group, n being an integer varying from 1 to 500,
R1 is, independently of each other' a monovalent group'
cation,notablyanalkalimetal,alkalineearthmetalorammonium
( ii)
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notably a hYdrogen' a
cation or a C1-C5 alkYl
25
group and preferably a Cr-Cs alkyl group; and
R2 is a monovalent group, notably a hydrogen, a hydroxyl or a c1-c1s alkyl'
preferablY R2 is a hYdroxYlgroup'
The polymer to be grafted will not necessarily include polyoxyalkylate groups from
the moment that the gem-bisphosphonate compound includes polyoxyalkylate groups'
The grafting reaction may advantageously be conducted at a temperature above
l2O.C,preferablybetweenl50and2oo"c,andinparticularbetweenlT0andlsO"c'The
waterformedbythereactionisthenremovedfromthereactionmixturebyevaporation
and the reaction product is recovered as a dry residue'
Thecarboxylicorphosphonicgroupspresentinthereactionproductmaythenbe
totally or PartlY neutralized'
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[Admixture]
According to a further aspect, the invention proposes an admixture for
suspensions of mineral particles, comprising the described copolymer.
ln order to facilitate the application and dosage thereof, the admixture may be
formulated as a solution in a suitable solvent'
preferably, the suitable solvent comprises or consists of water. ln certain cases,
the use of another solvent, such as an alcohol or a glycol may be contemplated'
additionally or alternatively, for example in order to facilitate solubilization'
The concentration of polymer in the admixture mainly depends on the
contemplated application. Generally, the admixture comprises from 1 to 50, preferably 10
to 30% by weight of polymer based on the totalweight'
Alternatively, the admixture may also appear in dry form notably as a powder'
The formulation of the admixture may moreover comprise other usual additives'
such as anti-foam agents, acceleratorq retardants, water-repellent agents, de-aerating
agents, other dispersants, air entraining agents or stabilizers of anti-foam agents'
[Useofthecopolymersaccordingtotheinvention]
According to a fourth aspect, the invention provides the use of the admixture for
fluidifying suspensions of mineral particles and for maintaining the workability of hydraulic
binders.
As hydraulic binders, mention may be made in particular of cement compositions
and notably concretes notably pre-fabricated concretes and ready-to-use concretes'
These concretes may notably be intended for the building and civil engineering industry'
Theamountofadmixturetobeaddedtothesuspensionofmineralparticlesof
coursedependsonthesoughtpropertiesandonthecontemplatedapplication.ltis
observed that for the preferred compositions of the invention, this dosage on the other
hand varies litile with the nature of the medium, and in particular, little with the chemical
composition of the cements used'
Generally, for a cement composition, an admixture dosage from 0'01 lo 2o/o'
preferably from 0.05 to1% and most particularly from 0.1 a 0'5% by weight of polymer
based on the weight of the cement is suitable for most standard applications'
Asanindication,aneffectivedosageofadmixtureforpreparingaready-to.use
concrete composition is from 0.7 to 1.5% of a 20% dry extract weight formulation based
on the weight of cement.
The action mechanism of the described polymers is not entirely understood' it
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I
being understood that that of superplasticizers in cement is still not fully elucidated in a
generalway.
However, it is assumed that the fluidifying effect of the superplasticizers mainly
results from repulsion forces set into play between the copolymers absorbed on the
surface of the grains.
The combined presence, in the copolymers with gem-bisphosphonate groups
according to the invention, of long polyoxyalkylate chains having a dispersion effect and of
phosphonate groups having strong capability for complexation and an exceptional
absorption power towards di- or tri-valent cations such as calcium or aluminium cations, is
assumed to be the reason for the particular properties as an admixture'
Moreover, it was surprisingly observed that the gem-bisphosphonate copolymers
according to the invention have an excellent water reducing power/rheology maintenance
compromise over a large range of concentrations of polyoxyalkylate chains.
!t was further observed that the copolymers according to the invention have low
sensitivity to the alkaline sulfates notablypresent in cement.
lndeed, the conducted tests have shown that functionalization of the PCPs by
gem-bisphosphonatesynthons gives the possibility of perturbing the adsorption of sulfate
ions at the surface of the cement particles and therefore promoting that of the
functionatized copolymer and consequently its dispersant action.
This adsorption strongly decreases in the case of high sulfate ion contents as a
result of the adsorption competition on the surface of the cement grains, between sulfate
ions and the copolymer. Thus, high contents of soluble sulfates generally lead to a low
reduction of water, probably due to a lower initial adsorption of the copolymer. However,
better workability of the compositions is observed most often, which presumably is related
to better availability of the copolymer in the interstitial liquid which gives the possibility of
extending the disPersant effect.
Moreover, the copolymer according to the invention advantageously has low
sensitivity to the clays often present in sands and limestone fillers making up the
suspensions of mineral particles.
lndeed, the presence of clays in the hydraulic compositions affects the efficiency of
the superplasticizers because of their adsorption on the surface of these clays and of the
insertion of their polyethoxylated grafts into the interfoliar spaces of these clays. Decrease
in the maintaining of fluidity then requires an increase in the admixture dosage, which in
turn generates costs and beyond which degradation of other properties may be caused,
such as the compression strength and durability of the material and which may moreover
lead to the occurrence of cracks.
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It is assumed that this advantageous effect is related to the fact that the presence
of gem-bisphosphonate groups in the copolymers according to the invention increases
their affinity for the surface of the cement grains to the expense of that of the clay
particles. This phenomenon may be due to the provision of additional anionic charges,
related to the substitution of a carboxylate group with 4 phosphonate functions, which
makes the approach towards the clays more difficult and therefore the adsorption at their
surface.
The obtained grafted copolymers as described above are of particular interest as
plasticizers for suspensions of mineral particles, notably of cement compositions and
plaster formulations.
lndeed, they have:
- high water reducing power,
- insensitivity to the alkaline sulfates of the cements,
- decrease in the sensitivity to clays present in the sands,
- very good fluidifying power of hydraulic compositions with very good retention of
fluidity.
[Compositions of mineral particles]
Finally, according to a last aspect, the invention is directed to a composition of
mineral particles comprising the copolymer according to the invention.
The compositions thus with an admixture have prolonged workability with low
dosage, including in the presence of high contents of alkaline sulfates and/or.clays.
Consequently they are of interest for a wide range of applications, in pafiicular
readyto-use concretes, self-compacting concretes, high or ultra high performance
concretes (HPC or UHPC) or precast concrete.
The invention will be better explained with reference to the examples which follow,
given as non-limiting examples.
EXAMPLES
A. Preparation of the bis-phosphonatesvnthon
EXAMPLE 1
Preparation of 1-hvdroxvethvlene -1 ,1 -bisphosphonic acid(HEDP)
n
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YO'
11
'rto, _
PC13
o
HO._ll Ho-'\1
Ho)p"oH
HO- ll o
HEDP
o
n
10
!n a 1,000 mL three-neck flask, provided with magnetic stirring, surmounted with a
condenser and with nitrogen inertization and placed 1n a thermostated oil bath and
connected to a vacuum pump, 609 (1 mole) of acetic acid, 1239 (1.5 moles) of
phosphorous acid and 500 mL of anhydrous chlorobenzene are loaded. The mixture is
brought to a temperature of 100'C with stirring. The formation of a homogenous solution
is observed. 2069 (1.5 moles) of phosphorus trichloride (PCls) are then slowly added into
the medium. The reaction mixture is maintained at 100"C for a further three hours and
then left to cool at room temperature. The solid residue obtained is washed with
chlorobenzene and then dissolved in 500 mL of water and brought to boiling with reflux for
t hour. After cooling, the solution is treateO with active carbon and then filtered. The raw
acid precipitates by adding an excess of hot methanol and after separation, the product is
recrystallized from one liter of water at 100'C.
The yield is 87o/o of 1-hydroxy ethylene-1,1-bisphosphonic acid. The reaction
product is characterized with 3tP NMR (CDClo), 'H NMR (CDCls) and 13C NMR'
nrr.r Aon H3PO3/ PCl3
H,N
AHP
ln a 1,000 mL three-neck flask provided with magnetic stirring, surmounted with a
condenser and with nitrogen inertization and placed in a thermostated oil bath and
connected to a vacuum pump, 91g (1 mole) of 3-aminopropionic acid, 1 239 (1.5 moles) of
phosphorous acid and 500 mL of anhydrous chlorobenzene are added. The mixture is
brought to a temperature of 100'C with stirring. The formation of a homogeneous solution
is observed. 2069 (1.5 moles) of phosphorus trichloride (PCl3) are then slowly introduced
into the medium. The reaction mixture is maintained at 100"C for a further three hours and
15
o
o
il -oH
Ho.. zPioH /\., o.oH
ir-oll
o
20
EXAMPLE 2
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then left to cool at room temperature. The obtained solid residue is washed with
chlorobenzene and then dissolved in 500 mL of water and brought to boiling with reflux for
t hour. After cooling, the solution is treated with active carbon and then filtered' The raw
acid precipitates by addition of an excess of hot methanol and after separation' the
product is recrystallized from one liter of water at 100'C'
The yield is 82o/o of 1-hydroxy-3-amino-propylene-1,1-bisphosphonic acid' The
reaction product was characterized with 31p NMR (CDC|.), tH NMR (CDCI3) and t'c NMR'
'trN-'^-AoH H3PO3' PCl3
BHP
lna1,000mLthree-neckflaskprovidedwithmagneticstirring,surmountedwitha
condenser and with nitrogen inertization and placed in a thermostated oil bath and
connected to a vacuum pump, 1o5g (1 more) of 4-aminobutyric acid, 123g (1'5 mores) of
phosphorous acid and 500 mL of anhydrous chlorobenzene are loaded' The mixture is
brought to a temperature of 100"c with stirring' The formation of a homogeneous solution
is observed. 2069 (1.5 mores) of phosphorus trichroride (pcrs) is then srowry intrbduced
into the medium. The reaction mixture is maintained at 100'c for a further three hours and
then left to cool at room temperature' The obtained solid residue is washed with
chrorobenzene and then dissorved in 500 mL of water and brought to boiling with refrux for
thour.Aftercooling,thesolutionistreatedwithactivecarbonandthenfiltered'Theraw
acid precipitates by addition of an excess of hot methanol and after separation' the
product is recrystallized from a liter of water at 100'C'
The yield is 77o/o of 1-hydroxy-4-amino-butylene-1,1-bisphosphonic
acid' The
reaction product was characterized uy'ip NMR (cDCl.)' 'H NMR (cDclg) and "C NMR'
;* ng a non-functionalized reference phosphorus-containing copolymer
(Example 4), tests for grafting the phosphonatesynt'"" *:1":"^:^:::
f::^:::
n o
ll-oH
,P'. H' ,N-<'-oH Ho' \P--oH
il-on
o
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EXAMPLE 3
;"il": ; ";;;" determine the best operatins conditions (examples 5A-5c)' rhese
EXAMPLE 4
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grafting conditions were then used for grafting HEDP, AHP and BHP synthons at different
levels (Examples 6A-6C, 7A-7C et 8A-8C).
ln a 500 mL two-neck flask provided with magnetic stirring, surmounted with a
condenser and with nitrogen inertization and placed in a thermostated oil bath, 73'579
(323.4 mmoles) of polymethacrylic acid (TP 941, marketed by COATEX, acid index
181.1mg KOH/g) are loaded and then 0.489 (5.95 mmoles) of soda (aqueous solution with
5Oo/o by weight of NaOH) are introduced. One then proceeds with loading 34.359
(46 mmoles) of methoxypolyethyleneglycol (MPEG) with a molar mass of 750 g/mol and
then with 91.609 (46 mmoles) of methoxypolyethyleneglycol (MPEG) with molar mass
2,OOO g/mol and the temperature of the reaction medium is brought to 175'C' When the
temperature of the reaction medium attains 1oo'c, the reactor is put under partial vacuum
(<20 mbars). -u
The moment when the reaction medium becomes homogeneous is taken as T0,
the time of the beginning of the reaction. The esterification reaction is left to continue for
7 hours at 175'C before allowing the reaction medium to return to room temperature'
An anhydrous base is obtained having a comb copolymer mass of 147 '59 i'e'
73.8o/o based on the initial reaction mixture'
ln order to evaluate the effect of the reaction conditions on the grafting of the
polycarboxylicacid,Example4wasrepeatedbyvaryingthemomentwhenthe
gem-bisphosphonate reagent HEDP is introduced, as prepared in the previous examples'
ln Example 4, the reaction is conducted without adding any gembisphosphonatesynthon
so as to be used as a reference' ln the Examples 5A' the gembisphosphonatesynthon
(HEDP) is added at the beginning of the reaction' when the
reaction medium becomes homogeneous (TO) and 4 hours after this moment'
respectivelY.
The reaction mixtures from these reactions are analyzed in terms of acid index and
of residual MPEG content by GPC according to the following procedure'
ln a first phase, MPEG standards with increasing concentrations are injected and
then the corresponding areas are determined' Measurement of the area of the MPEG
peak of the sample to be analyzed gives the possibility of accessing the residual MPEG
n
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gAMPLES 5A - 5C
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5
n
/a
10
14
level. The injections are accomplished at 40'C, the columns used are Aquagel Guard OH
8pm (marketed by Agilent Technologies) positioned in series with two Aquagel OH30
columns (also marketed by Agilent Technologies).
The results are summarized in the table 1 above
It is seen that the simultaneous introduction of the gem-bisphosphonatesynthon
with the polyalkoxylated compounds perturbs the esterification reaction.
Deferred introduction into the reaction medium on the other hand, for example
after 4 hours of reaction, gives the possibility of again finding an MPEG grafting level
equivalent to that of the reference reaction without any phosphonatesynthon'
These operating conditions are the ones which were retained for the subsequent
study.
lna500mLtwo-neckflaskprovidedwithmagneticstirring,surmountedwitha
condenser and with nitrogen inertization and placed in a thermostated oil bath' 73'57g
(323.4 mmoles) of polymethacrylic acid (TP 941, marketed by coATEX, acid index
181.1mg KOH/g) are loaded and 0.489 (5.95 mmoles) of soda (aqueous solution with
50% by weight of NaOH) are then introduced. lt is then proceeded with the loading of
34.359 (46 mmoles) of methoxypolyethyleneglycol (MPEG) with a molar mass of
750 g/mol and then with 91.609 (a6 nrmoles) of methoxypolyethyleneglycol (MPEG) with a
molar mass of 2,ooo g/mol and the temperature of a reaction medium is brought to 175'C'
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EXAMPLE Reaction mixture HEDP Acid
index lA
Residual
Amount Polyox.
[molar %]
!ntroduced
4
(EPB 662054)
Methacrylic acid
MPEG
N/A 20.384 3.87o/o
5A
(EPB 662055)
Methacrylic acid
MPEG 4
At the
start
36.741 29.84o/o
5B
(EPB 662056)
Methacrylic acid
MPEG 4
At TO 33.424 27.88%
5C
(EPB 662058)
Methacrylic acid
MPEG 4
At T0+4h 33.769 3.83o/o
EXAMPLE 6A.6C
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15
When the temperature of the reaction medium attains 1OO"C, the reactor is set under
partial vacuum (<20 mbars).
The moment when the reaction medium becomes homogeneous is taken as T0,
the time of the beginning of the reaction. After 4 hours of baking at 175'C, 4'11 g of
bisphosphonatesynthon according to Example 1 are introduced very slowly and the
esterification reaction is left to furlher continue for 3 hours at 175"C before allowing the
reaction medium to return to room temperature.
An anhydrous base is obtained having a mass of grafted copolymer of 143.3 g i'e.
71.7o/o based on the initial reaction mixture'
The obtained solution of copolymer bearing carboxylic functions, polyether grafts
and gem-bisphosphonic units, is then formulated by adding 0.5% by weight of oleic amine
with 2 moles of ethylene oxide (marketed under the name of NOMMOX 02 by CECA)
and 1.20/o by weight of tributylphosphate (antifoam agent).
Finally, the product is diluted with water in order to obtain a 2Oo/o dry extract and it
is neutralized with sodium hydroxide at pH 7'
The thereby prepared dispersant is ready to use'
n
n
15
Example 6 is repeated but however replacing
HEDP with the amount of gem-bisphosphonicsynthon
the gem-bisPhosPhonicsYnthon
AHP prePared in ExamPle 2
25
30
indicated in Table 2 below.
An anhydrous base is obtained having a mass of grafted copolymer of 144'59 i'e'
72.60/o based on the initial reaction mixture'
The obtained solution of copolymer bearing carboxylic functions, polyether grafts
and gem-bisphosphonic units, is then formulated by adding 0'5% by weight of oleic amine
with 2 moles of ethylene oxide (marketed under the name of NoRAMOX Oz by CECA)
and1,2o/obyweightoftributylphosphate(antifoamagent)'
Finally,theproductisdilutedwithwaterinordertoobtaina2Oo/odryextractandit
is neutralized with sodium hydroxide at pH 7'
The thereby prepared dispersant is ready to use'
EHMPLE 7A.C
A
EX. PCP type
copolymer
Gem-bisphosPhon icsYnthon
Type Proportion
[molar %]
Mass [g]
6A EPB 762.013 HEDP 2 145.5
6B EPB762.014 HEDP 4 143.3
6C EPB 762.015 HEDP 6 141.1
7A EPB762.022 AHP 2 146.1
7B EPB762.023 AHP 4 144.5
7C EPB 762.024 AHP 6 142.9
8A EPB762.034 BHP 2 146.1
EPB 762.035 BHP 4 144.6
8B
BHP 6 142.9
8C EPB 762.036
9A EPB 762.013 ND
+ EPB 709028
HEDP 2
9B EP8762.014 +
+ EPB 709028
HEDP 4
ND
9C EPB 762.015 + ND
+ EPB 709028
HEDP 6
EXAMPLE 8A.C
E
!t
Example 6 is repeated but however by replacing the gem-bisphosphonicsynthon
HEDP with the amount of gem-bisphosphonicsynthon BHP prepared in Example 3 as
indicated in Table 2 above'
An anhydrous base is obtained having a mass of grafted copolymer of 144'69 i'e'
72.73o/o based on the initial reaction mixture'
Theobtainedsolutionofcopolymerbearingcarboxylicfunctions,polyethergrafts
and gem-bisphosphonic units, is then formulated by adding 0'5% by weight of oleic amine
with 2 moles of ethylene oxide (marketed under the name of NoRAMOX 02 by CECA)
and 1.2o/oby weight of tributylphosphate (anti foam agent)'
Finally, the product is diluted with water in order to obtain a20% dry extract and it
is neutralized with sodium hydroxide at pH 7'
The thereby prepared dispersant is ready for use'
10
15
10
17
EXAMPLE gA-C
Preparation of copolvmers of the PCP tvpe srafted with HEDP
Example 6 is repeated but however by adding in the final copolymer a proportion
of copolymer of the EPB 729.028 type obtained under the operating conditions of
Example 4 but only containing carboxylic functions and methoxypolyethyleneglycol with a
molar mass of 2,000 g/mol.
The obtained solution of the mixture of copolymers bearing carboxylic functions,
polyether grafts and gem-bisphosphonic units, is then formulated by adding 0.5o/o by
weight of oleic amine with 2 moles of ethylene oxide (marketed under the name of
NORAMOX 02by CECA) and 1.2o/oby weight of tributylphosphate (antifoam agent).
Finally, the product is diluted with water in order to obtain a 20o/o dry extract and it
is neutralized with sodium hydroxide at pH 7.
The thereby prepared dispersant is ready for use'
C. Evaluation of the applicationproperties
1. Water reducinq Power '
ln order to evaluate the water reducing power of the copolymers according to the
invention, mortars were formulated by adding the prepared copolymers to Examples 6 to 9
as a plasticizer.
The composition of the prepared mortar is detailed in Table 3 below' The
non-grafted copolymer (Example 4 EPB 662054 and the mixture EPB 762'014 + EPB
729.028, respectively) is used as a reference (REF)'
Themortarispreparedaccordingtothefollowingprocedure:
TwostandardizedFULCH|RoNsandsareintroducedintothebowlofaPERR|ER
kneader. After kneading the sands for 30 seconds at a rate of about 140 rpm' the
pre_wetting water which represents 1t3 of the totar water to be introduced is added within
15 seconds. The mixing is continued for 15 seconds before leaving the mass at restfor
4 minutes. Next, the cement and the limestone flller (origin: ERBMY provided by MEAC)
are introduced and the mixing is then continued for 1 minute before adding the remainder
of the mixing water as well as the totality of the admixture within 30 seconds' The kneader
is then stopped for a few instants in order to scrape the edges of the kneading bowl to
have a proper homogenous mass and mixing is then continued for again 1 minute at a
fast rate of 280 rPm.
n
n
20
15
25
30
n
n
10
18
Table 3 : Composition of the mortar used for evaluatino workabilitv
Component' Mass [g]
CEM I (Le Havre cement 01/10) 624.9
ERBLAY filler 412.1
AFNOR sand 1350
FULCHIRON sand 587.7
Totalwater 375.1
The'workability of the mortars formulated with the copolymers according to the
invention was evaluated by measuring the spread diameter (slump flow) according to the
procedure described hereafter.
A mold of frustoconical shape without any bottom reproducing the Abrams cone
(see standard NF 18-451, 1981) at a scale of 0.5 is filled; in order to carry out spreading,
the cone is lifted perpendicularty to the plate by completing a quarter turn. The spreading
is measured at 5, 30, 60 and 90 minute! along 2 diameters at 90' with a tape measure.
The result of the spreading measurement is the average of the 2 values to within +/-
1 mm. The tests were carried out at 20"C.
The dosage of the grafted copolymer is determined so as to attain a target spread
comprised between 310 and 330 mm. Unless indicated otherwise, the dosage is
expressed in percent by weight based on the total weight of the binder (filler + cement)'
The results obtained for the mortars formulated with the copolymers grafted with
HEDP of Example 6 are transferred into Table 4 below'
Upon examining the results, it is seen that the grafting with 2 or 4o/o of HEDP gives
the possibility of substantially lowering the dosage (passing from 0.60% to 0'35%) for an
equivalent initial sPread.
15
20
n
EX. Grafting
[molar % ]
Dosage
lo/ol
Spreading T [mins] Loss of
fluidity
l%ol
5 30 60 90 120
REF 0.5 335 325 300 280 245 26.87
REF 4% HEDP
without
grafting
0.5 315 310 290 270 245 22.22
6A 2o/o HEDP 0.35 320 245 190 165 125 60.94
6B 4o/oHEDP 0.35 340 275 220 195 155 54.41
6C 60lo HEDP 0.35 340 225 195 155 125 63.24
It is moreover verified that by simply adding to the control formulation, 4o/o of
HEDP, (EPB 760.020), which is then not grafted to the copolymer' it is not possible to
modify the water reducing power of the cbntrol grafted copolymer.
lmprovement in the water reducing power of the bis-phosphonic grafted
copolymers may be explained by a larger affinity for the surface of the cement grains'
The results obtained for the mortars formulated with the AHP-grafted copolymers
prepared in Example 7 as described earlier are transferred into Table 5 below'
Spreading T minsl Loss 6f
fluidity
t%l
EX.
REF
REF
Grafting
[molar %]
Dosage
lo/"1 5 30 60 90 120
0.5
o5
335 335 290 270 245 26.87
340 340
245
320 310 280 17.65
215 170 155 53.73
7A 2o/o AHP 0.35 335
175 140 120 62.50
7B 4o/o AHP 0.35 320 225
235 200 170 140 58.82
7C 6% AHP 0.3s 340
lt is seen that by grafting 2,4 or 6% of AHP, it is also possible to lower the dosage
of superplasticizer (passing from 0.50% to 0.35%) for an equivalent initial spread'
The results obtained for the mortars formulated with the BHP-grafted copolymers
prepared in Example 8 as described earlier are transferred into Table 6 below'
5
10
A
15
n
Table 6: spreadino of a mortar with an admixture of copolvmers of example 8
EX. Grafting
[molar %]
Dosage
l%ol
Spreading T [mins] Loss of
fluidity
lYol
5 30 60 90 120
REF 0.5 330 330 315 260 245 25.76
REF o.4
OA
330 330 270 225 175 46.97
330 270 245 190 160 51.52
8A 2o/oBHP
8B 4o/o BHP 0.4 340 290 265 200 165 51.47
8C 6% BHP 0.35 320 200 160 125 120 62.50
The obtained results show that the grafting of 2 or 4o/o ol BHP also allows lowering
of the dosage (passing from 0.5% to 0.4%) for an equivalent initial spread'
with the results presented above, it is possible to conclude that the introduction of
bis-phosphonic units on a PCP backbone modifies the water reducing power of the
copolymers
withoutintendingtobeboundbyanytheory,thisobservationmaybeexplainedby
increased affinity of the grafted copolymers for the surface of the cement particles'
Moreover, it was surprisingly observed that these polymers with
gem-bisphosphonate groups give the possibility of significantly improving the water
reducing power without degrading the maintenance of rheology on a wide rarlge of
concentrations of polyoxyalkylene chains in the copolymer, expressed by the ester level in
Table 8.
10
.\15
CEMI52,5 R SPLC
20
Table 8: Spreadinq of a mortar with # admixture of copolvmers of Examnle 9
SPLC 52,5 R Commerc
ial
dosage
I&I
Dry
dosag
e [%]
Spread [mm] MPEG
2000
level
HEDP
!evel
Overall
ester
level
5 3 60
EPB 819019 1.20 0.30 315 315 310 25 q 25
EPB 819012 1.00 0.25 310 320 310 25 t 29
EPB 819027 0.85 0.21 300 295 295 25 q 33
EPB 819035 0.50 0.13 305 275 290 25 12 37
EPB 819036 0.50 0.13 290 275 285 25 16 41
It is seen upon examining Table 8 above that by using an additive including a
polyalkoxylatedpolycarboxylic copolymer grafted with 4% and 8% of HEDP in a cement
formulation it is possible to reduce the dosage of superplasticizer with maintaining fluidity
over time.
2. Sensitivitv to alkaline sulfates
ln order to evaluate the impact of the presence of alkaline sulfates on the efficiency
of the copolymers according to the invention as a superplasticizer, one proceeded with
tests with mortars having variable sulfate content.
The content of alkaline sulfates in the mortars was modified by adding poridered
potassium sulfate to the cement (0.3 and 0.6% by weight based on the drytdry weight of
the cement). The mortar was then prepared according to the formulation indicated in
Table 9 below, by adding to the mixing water, the indicated dosage of reference
copolymer.
The spread of these mortars was evaluated as described above.
10
n
15
A
Table 9: Composition of the mortar u33d for evaluatino the sensitivitv to sulfates
Component Mass [g]
CEM I (Le Havre cement 01/10) 624.9
ERBLAY filler 412.1
AFNOR sand 1 350
FULCHIRON sand 587.7
Totalwater 375.1
The obtained results are transferred into Tables 10 and 1 1 below, respectively.
The indicated total sulfate concentration takes into account the level of alkaline
compounds initially present in Le Havre cement (LH), evaluated to be 0.25% by weight
(dry/dry basis).
It is observed that the referenced superplasticizer dosage required for obtaining a
targeted spread is nearly trebled in the'presence of an additional 0.6% by weight of
alkaline sulfate.
The tests were then repeated by using the copolymer of Example 68 (grafted with
4% of HEDP) in the mortar formulation. The obtained results are summarized in Table 11
below.
10
A
15
Table 10 Effect of the sulfates - reference superplasticizer
EX. Grafting
[molar %]
Added
K2SO4[%
by weight
of the
cementl
Total
alkaline
sulfates
lYo by
weightl
Dosage
t%ol
Spread T [mins]
5 30 60 90 120
REF 0.25 0.5 320 295 240 180 140
REF 0.3 0.55 0.8 310 305 270 230 200
REF 0.6 0,85 1.3 325 320 315 300 280
A
Table 11' Effect of the sulfates - copiimer of Examole 6. constant spread
EX. Grafting
[molar o/o]
Added
KzSOd% by
weightl
Dosage
lYol
Spread T [mins]
5 30 60 90 120
REF 0.5 320 295 240 180 140
REF 0.3 0.8 310 305 270 230 200
REF 0.6 1.3 325 320 315 300 280
6B 4% (HEDP) 0.35 310 200 150 110 1'10
6B 4% (HEDP) 0.3 0.5 340 325 290 260 215
6B 4% (HEDP) 0.6 0.5 265 230 200 170 150
These results demonstrate the interesting effect of the copolymers according to the
invention at the level of sensitivity to the presence of alkaline sulfates. lndeed, it is seen
that the copolymer according to the invention tolerates much higher alkaline sulfate levels
in the cement as compared with the refeiEnce plasticizer.
ln order to better evaluate the insensitivity to the sulfate ions brought by the
bisphosphonic functionalization, the previous tests were repeated, with the same mortar
composition, by adding and increasing concentration of potassium sulfate but by imposing
constant dosage.
The results obtained for the copolymers of Example 6,A and 68 are collected in
Table 12 below.
The results demonstrate that functionalization with 4% of HEDP giv6s the
possibility of suppressing the detrimental effect ol0.4o/o by weight of alkaline sulfate in the
cement under the conditions of the test.
Moreover, it is seen that a copolymer grafted with 2o/o of HEDP in a cement mortar
loaded with 0.3% by weight of potassium sulfate has a similar behavior or even a slightly
superior behavior in maintaining rheology as that of the reference. ln other words, grafting
of the reference copolymer with 2o/o of HEDP gives the possibility of suppressing the
detrimental effect of 0.3% by weight of potassium sulfate presence in a cement.
10
15
20
24
A
Table 12 :Effect of the sulfates - copolvmers of Example 6. constant dosaqe
EX. Grafting
[molar %]
Added
K2SOa[% by
weight l
Dosage
t%t
Spread T [mins]
5 30 60 90 120
REF 0.5 310 275 220 170 145
6A ZYo (HEDP) 0.4 340 280 200 155 120
6A 2o/o (HEDP) 0.3 0.5 320 310 280 230 180
6A 2o/o (HEDP) 0.6 0.5 225 185 160 140 120
REF 0.5 320 300 255 200 160
6B 4% (HEDP) 0.3 0.5 uo 325 290 260 215
6B 4% (HEDP) 0.4 0.5 320 300 255 210 175
6B 4% (HEDP) 0.5 0.5 295 270 215 185 160
6B 4% (HEDP) 0.6 0.5 265 230 200 170 150
The use of the copolymers according to the invention as a superplasticizer is
therefore less sensitive towards alkaline sulfates in the cements, as compared with the
nongrafted copolymer. This observation may be explained by a complexing power of the
phosphorate group towards calcium ions which is greater as compared with sulfate ions.
3. Sensitivitv to clavs
Superplasticizers are also sensitive to the presence of clays in the compositions,
generally in the sands.
ln order to evaluate this sensitivity of the copolymers according to the invention,
the spreading of mortars formulated with sand polluted with a clay (montmorillonite KSF)
was measured and compared with that of a mortar formulated with a clean non-polluted
sand.
Unless indicated otherwise, the clay percentage is expressed in percent by dry
weight based on the total dry sand, consisting of AFNOR sand and of FULCHIRON sand,
the added clay is introduced with the sand before adding pre-wetting water.
The mortars were prepared according to the formulation indicated in Table 7
above, by using the cement with a strong level of alkaline compounds (CEM I 52,5 N
cement from Saint Pierre la Cour, marketed by Lafarge) and the copolymer according to
Example 98 (mixture of EPB 762.014 grafted with 4% HEDP and of EPBTzg.oz9).
The results of the tests are shown in Table 13 below.
5
10
15
20
25
These results show that the studied copolymers according to invention are
significanly less sensitive to clay present in the sands, to the extent of widely neutralizing
the detrimental etfect of 1o/o by weight of clay (based on dry sand) on the fluidity of the
cement comPosition.
Table 13: Clav effect - copolvmer of example 9
EX. Grafting
[molar %]
Added clay
* lo/o bY
weightl
Dosage Spread T [mins]
5 30 60 90 120
REF 1.0 315 295 290 285 280
REF 1 1.0 180 160 145 120 110
REF 1 1.2 215 180 170 160 150
9B 4olo (HEDP) 1 1.0 275 250 240 225 210
9B 4olo (HEDP) 1 1.2 335 320 300 295 285
*The added claY is KSF mo marketed ALDRICH
4. Efficiencv on composite cements
ln order to evaluate the robustness of the copolymers according to the invention,
the superplasticising effect was studied on composite cements with different composition.
More specifically, a cement was tested, including as a substitution binder, flying
ashes (CEM ll /A-V cement (Saint Pierre La Cour, marketed by I'AFARGE))' The mortars
were prepared according to the formulation given in Table 9 and added with admixture
with various dosages of copolymer of Example 98'
The spreading values obtained for these mortars are collected in Table 14 below.
Table 14: Effect on flvinq ash cement
EX. Grafting
[molar %]
Dosage
%l
Spread T [mins]
5 30 60 90 120
REF 1.0 325 315 310 300 260
9B 4% (HEDP) 1.0 360 370 380 380 370
9B 4% (HEDP) 0.8 320 340 345 340 320
by
10
15
I'he obtained results show that
'.
;: presence of flying ashes, the copolymers
according to the invention have a higher water reducing power than the reference
superplasticizer.
Moreover, it is noted that by reducing the dosage by 20o/o of the copolymer
5 according to the invention it is possible to obtain a cement composition having a
rheological behavior in terms of maintaining fluidity, superior to that of the reference
superplasticizer.
On the other hand, a cement including as a substitution binder a slag (CEM lll/A
42,5 N-LH PM-ES-CP1 (marketed by Lafarge) of the following composition, was tested:
10 - Clinker 35o/o by weight (C3A 8.6% - C3S 600/o - C4AF 1 1)
n - Slag 62o/oby weight
- Secondary constituents 3% by weight
- Gypsum 4.8o/o bY weight.
The mortars were prepared according to the formulation given in Table 9 and
15 added with admixture with different dosages of copolymer of Example 98,
fhe spread values obtained for these mortars are collected in Table 15 below.
Table 15: Effect on slaq cement
EX. Grafting
[molar %]
Dosage
%l
Spread T [mins]
5 30 60 90 120
REF 0.5 325 345 330 300 280
9B 4% (HEDP) 0.5 380 390 380 330 310
9B 4% (HEDP) 0.4 325 320 260 225 190
20
The obtained results show that in the presence of slag as a substitution binder, the
copolymers according to the invention have a higher water reducing power than the
reference superplasticizer.
The experimental data above confirm the benefit of the copolymers according to
25 the invention as a superplasticizer for compositions of hydraulic binders. These
copolymers actually have a higher water reducing power, low sensitivity to alkaline
sulfates and to clays as well as high robustness and good maintenance of rheology in a
wide range of ester levels.
5
27
HE CLAIMS
1. A copolymer comprising a main hydrocarbon chain and side groups, wherein
the side groups comprise carboxylic groups,polyoxyalkylate groups and gembisphosphonate
grouPs.
2. The copolymer according to claim 1, wherein the polyoxyalkylate side groups
are bound to the main chain through an ester, ether or amide bond.
3. The copolymer according to one of claims 1 or 2, wherein the
gem-bisphosphonate groups stem from grafting with a compound selected from 1-
hydroxyethylene-1,1-bisphosphonic acid(HEDP), 1-hydroxy-3-amino-propylene-
1,l-bisphosphonic acid (AHP) and 1-hydroxy-4-amino-butylene-1,1-
bisphosphonic acid(BHP).
154. The copolymer according to one of claims 1 or 2, wherein the gembisphosphonatesidegroupsfittheformula(
lA)belowthe:
-L-X-C
I
R2
20 wherein:
L represents a group for binding to the main chain, in particular a bond, and
oxygen atom, a group -NR4-, (Rr being a hydrogen or a Cr-Cs alkyl group)' or an
alkylene group, preferably, L is an oxygen atom or a group -NRa-'
X is a spacer group, in particular a C1-C2solkylene group optionally substituted or a
chain of groups of formula -(QO).- wherein Q represents an alkylene group with 2
to 4 carbon atoms or a mixture of these alkylene groups, n being an integer
varying from 1 to 500, preferably, X is a Cr-Coalkylene group;
Rl is, independently of each other, a monovalent group, notably a hydrogen, a
cr-co alkyl group or a group of formula -(QO)nR5 wherein Q represents an
alkylene group with 2 to 4 carbon atoms or a mixture of these alkylene groups, n is
10
o
lllo-R1
7P-o-R1
\ ,'O-R1
ofi- o-*'' (tA)
25
30
an integer varying from 1 to 500 ,"it*. is a hydrogen or a Cr-Cs alkyl or R1 is a
cation, notably an alkali metal, alkaline earth metal or ammonium cation; and
R2 is a hydrogen atom, a hydroxyl group or a C1-C1s alkyl group'
5 5. The copolymer according to claim 4, wherein the gem-bisphosphonate groups
are of formula (lA), L being an oxygen atom, an amide group or an ester group.
6. The copolymer according to claim 4 or 5, wherein the gem-bisphosphonate
groups are of formula (lA), X being a Cr-Coalkylene group.
10
7. The copolymer according to one of claims 4 to 6, wherein the
gem-bisphosphonate groups are of formula (lA), R1 being a hydrogen atom or an
alkali metal, earth alkaline metal or ammonium cation'
15 B. The copolymer according -*to one of claims 4 to 7 , wherein the
gem-bisphosphonate groups are of formula (lA), R2 being a hydroxyl group.
9. The copolymer according to one of claims 1 to 8, wherein the polyoxyalkylate
groups are of the formula (ll) below:
20 -Re-Z-A (ll)
wherein:
R. is a cr-crzalkylene group or a c=o group or is further absent; and
Z is an oxygen atom or a group N-R4, R4 may be a hydrogen or a C1-C6 alkyl
group; and
25 A is a group of formula -(QO).-OR3 wherein:
Q represents an alkylene group with 2 to 4 carbon atoms or a mixture of
these alkYlene grouPS;
n is an integer varying from 1 to 500; and
R3 represents a hydrogen atom or a CrCp alkyl, aryl, alkylaryl or arylalkyl
30 grouP.
10. The copolymer according to claim 9, wherein, in the polyoxyalkylate groups of
formula (ll), A is a group of formula -(QO),-OR3 wherein R3 is a methyl'
35 11. The copolymer according to one of claims 1 to 10, urherein the carboxylic
grouPs fit the formula (lll) below:
10
29
-c(o)-o-Rd (lll)
wherein:
R6 represents H or or a crcn alkyl' aryl' alkylaryl or arylalkyl group or an
alkali metal, alkaline earth metal or ammonium cation'
12. A method for preparing a copolymer according to one of claims 1 to 11,
comprising the stePs:
(i) polymerizing a monomer bearing a carboxylic group, optionally in the
presenceofamonomerbearingapolyoxyalkylategroup;et
(ii) grafting the obtained polymer with a reactive gem-bisphosphonate
comPound.
13. The method according to claim 12, wherein the reactive gem-bisphosphonate
compound is selected from 1-hydroxyethylene-1,1-bisphosphonicacid (HEDP)'
15 1-hydroxy-3-amino-propylene-1,1:bisphosphonic acid (AHP) and 1-hydroxy-4-
amino-butylene-1, 1-bisphosphonic acid(BHP)'
14. An admixture for suspensions of mineral particles comprising the copolymer
according to one of claims 1 to 1 1, as a solution in a suitable solvent'
15. The admixture according to claim 14, comprising 1 to 50, preferably 10 to 30%
by weight of copolymer based on the totalweight'
16. The use of the copolymer according to one of claims 1 to 11 for fluidifying
25 suspensions of mineral particles'
17. The use of the copolymer according to one of claims 1 to 1'1 for maintaining
workability of hydraulic binders'
30 1g. The use of the copolymer according to one of claims 1 to 11 for reducing the
sensitivity of hydraulic compositions to clays'
19. The use of the copolymer according to one of claims 1 to 11 for reducing the
sensitivity of hydraulic binders to alkaline sulfates'
20
35
5
30
20. A composition of mineral particles comprising the copolymer according to one
of claims 1 to 11.