SYNTHETIC POLYMER RHEOLOGY MODIFIER AND WATER RETENTION AGENT REPLACEMENT FOR CELLULOSE ETHER IN CEMENT COMPOSITIONS

Abstract

The present invention provides substantially nonionic brush polymers having pendant polyether groups, preferably poly(alkylene glycol) groups, which polymers are useful as synthetic polymer substitutes for cellulose ethers in mortars and hydraulic binders. The brush polymers are preferably crosslinked, such as with ethylene glycol di(meth)acrylates.

Claims

1. A composition comprising a hydrophilic substantially nonionic vinyl or acrylic brush polymer having pendant polyether groups and having a weight average molecular weight of from 10,000 to 50,000,000.

2. The composition as claimed in claim 1, wherein the brush polymer has a weight average molecular weight of 250,000 or more.

3. The composition as claimed in claim 1, wherein the brush polymer comprises the polymerization product of a) from 70 to 100 wt. %, based on the total weight of the monomers used to make the polymer, of a macromonomer having a pendant polyether group, and b) as the remainder of the monomers used to make the polymer, lower alkyl (C.sub.1 to C.sub.4) alkyl (meth)acrylates, hydroxyalkyl (meth)acrylates, or their combination.

4. The composition as claimed in claim 3, wherein the macromonomer a) is chosen from a polyethylene glycol (meth)acrylate, a methoxy polyethylene glycol (meth)acrylate, a hydrophobic C.sub.12 to C.sub.25 alkoxy poly(alkylene glycol) (meth)acrylate, and combinations thereof.

5. The composition as claimed in claim 1, wherein the substantially nonionic brush polymer contains a combination of two or more pendant polyether groups chosen from polyalkylene glycols alkoxy, poly(alkylene glycol)s and hydrophobic C.sub.12 to C.sub.25 alkoxy poly(alkylene glycol)s.

6. The composition as claimed in claim 5, wherein the substantially nonionic brush polymer is crosslinked.

7. The composition as claimed in claim 1, wherein the substantially nonionic brush polymers contain as pendant polyether groups poly(alkylene glycol) side chains having from 5 to 50 ether or alkylene glycol units.

8. The composition as claimed in claim 7, wherein the pendant polyether groups are poly(alkylene glycol) side chains having from 7 to 15 ether or alkylene glycol units.

9. The composition as claimed in claim 1, wherein the hydrophilic substantially nonionic brush polymers of the present invention comprise the copolymerization product of a) one or more macromonomers chosen from polyethylene glycol (meth)acrylate (PEGMA) and methoxypoly(ethylene glycol) (meth)acrylate (MPEGMA).

10. The composition as claimed in claim 1, further comprising a cellulose ether.

11. A method of making the hydrophilic substantially nonionic brush polymers of the present invention comprising polymerizing in an aqueous medium one or more addition polymerizable macromonomer having a pendant polyether group in the presence of an initiator.

Description

EXAMPLES

[0063] The following examples serve to illustrate the invention. Unless otherwise indicated, the preparations and test procedures are carried out at ambient conditions of temperature and pressure.

Synthesis Examples 1-17

[0064] Synthesis Process:

[0065] All polymers were synthesized in an aqueous solution shot polymerization process via free radical polymerization. Unless otherwise specified, 500 mL 4-neck round bottom reaction flask coupled with a thermo-couple, an overhead stirrer and a condenser was used for all polymer synthesis and a heating mantel was used to control reaction temperature. Unless stated otherwise, all chemicals used were from Sigma Aldrich (St. Louis, Mo.). During polymerization, after the temperature rose to an indicated target temperature, a controlled initial dosage of initiators or redox packages was added and the temperature was held constant for two hours. After the two-hour polymerization, a second dosage of initiators or redox packages was used to reduce the amount of residual monomers and the temperature was held constant for two hours. After the second two-hour reaction, the reactor was cooled down to near room temperature before taking the solution sample out of reactor for analysis and performance tests.

Example 1

[0066] A brush polymer was made via the Synthesis Process, above, wherein the reactants comprised 180 grams of de-ionized (DI) water and 10 grams of methoxypoly(ethylene glycol).sub.10.8 methacrylate (MPEGMA475) monomer all charged in the reaction flask. Target temperature was set at 701 C. The initial dosage was a redox initiator package including 1 gram of 0.1 wt. % ethylenediamine tetraacetate (DETA) solution, 1 gram of 0.1 wt. % ferrous sulfate solution, 2 grams of 0.5 wt. % of reducing agent Bruggolite FF6M disodium salt of 2-hydroxy-2-sulfinatoacetic acid and 2-hydroxy-2-sulfonatoacetic acid (FF6) (Bruggemann Chemical, Chadds Ford, Pa.) and 2 grams of 0.5 wt. % ammonium persulfate (APS) aqueous solution. The second initiator dosage included 2 grams of 0.5 wt. % of FF6 and 2 grams of 0.5 wt. % APS aqueous solution.

Example 2

[0067] A brush polymer was made via the Synthesis Process, above, wherein the reactants were 180 grams of de-ionized water and 10 grams of MPEGMA475 monomer all charged in the reaction flask. Target temperature was set at 881 C. The initial dosage of initiator was 2 grams of 0.5 wt. % APS aqueous solution. The second dosage of initiator included 1 gram of 0.5 wt. % APS aqueous solution.

Example 3

[0068] A brush polymer was made via the Synthesis Process, above, wherein the reactants were 189 grams of de-ionized water and 10.3 grams of MPEGMA475 monomer all charged in the reaction flask. Target temperature was set at 701 C. The initial dosage of initiator was 0.4 grams of 0.5 wt. % APS aqueous solution. The second dosage of initiator included 1.5 gram of 0.5 wt. % APS aqueous solution.

Example 4

[0069] A brush polymer was made via the Synthesis Process, above, wherein the reactants were 177 grams of de-ionized water and 20.2 grams of MPEGMA750 monomer with 50 wt. % active all charged in the reaction flask. Target temperature was set at 701 C. The initial dosage of initiator was 2 grams of 0.5 wt. % APS aqueous solution. The second dosage of initiator included 1.5 gram of 0.5 wt. % APS aqueous solution.

Example 5

[0070] A brush polymer was made via the Synthesis Process, above, wherein the reactants were 191 grams of de-ionized water, 1.4 grams of MPEGMA475 and 4.0 grams of poly(ethylene glycol).sub.8.2 methacrylate (PEGMA360) monomers all charged in the reaction flask. Temperature was set at 601 C. The initial dosage was a redox package including 1.8 gram of 0.1 wt. % DETA solution, 1.8 gram of 0.1 wt. % ferrous sulfate solution, 0.12 grams of 0.5 wt. % of reducing agent FF6, and 0.10 grams of 0.5 wt. % ammonium persulfate (APS) aqueous solution. The second dosage of initiator included 1.5 grams of 0.5 wt. % of FF6 and 1.5 grams of 0.5 wt. % APS aqueous solution.

Example 6

[0071] A brush polymer was made via the Synthesis Process, above, wherein the reactants were 173 grams of de-ionized water and 20 grams of MPEGMA475 monomer all charged in the reaction flask. Temperature was set at 701 C. The initial dosage of initiator was 4 grams of 0.5 wt. % APS aqueous solution. The second dosage of initiator included 1 gram of 0.5 wt. % APS aqueous solution.

Example 7

[0072] A brush polymer was made via the Synthesis Process, above, wherein the reactants were 185 grams of de-ionized water and 10 grams of MPEGMA475 monomer all charged in the reaction flask. Temperature was set at 701 C. The initial dosage of initiator was 0.3 grams of 0.5 wt. % APS aqueous solution. The second dosage of initiator included 1 gram of 0.5 wt. % APS aqueous solution.

Example 8

[0073] A brush polymer was made via the Synthesis Process, above, wherein the reactants were 187 grams of de-ionized water, 9.6 grams of MPEGMA475 monomer and 0.40 grams of 0.5 wt. % ethylene glycol dimethacrylate (EGDMA) in a solution of MPEGMA475 all charged in the reaction flask. Temperature was set at 501 C. The initial dosage of initiator was 0.4 gram of a 0.5 wt. % Vazo 56 2,2-azobis(2-amidinopropane) dihydrochloride (Dupont, Wilmington, Del.) aqueous solution. The second dosage of initiator included 1 gram of a 0.5 wt. % Vazo 56 initiator aqueous solution.

Example 9

[0074] A brush polymer was made via the Synthesis Process, above, wherein the reactants were 187 grams of de-ionized water, 9.9 grams of MPEGMA475 and 0.26 gram of EGDMA monomers all charged in the reaction flask. Temperature was set at 701 C. The initial dosage of initiator was 0.37 grams of 0.5 wt. % APS aqueous solution. The second dosage of initiator included 1 gram of 0.5 wt. % APS aqueous solution.

Example 10

[0075] A brush polymer was made via the Synthesis Process, above, wherein the reactants were 177.3 grams of de-ionized water, 14.9 grams of MPEGMA475 and 0.19 gram of EGDMA monomers all charged in the reaction flask. Temperature was set at 701 C. The initial dosage of initiator was 0.5 grams of 0.5 wt. % APS aqueous solution. The second dosage of initiator included 1 gram of 0.5 wt. % APS aqueous solution.

Example 11

[0076] A brush polymer was made via the Synthesis Process, above, wherein the reactants were 188.6 grams of de-ionized water, 5 grams of MPEGMA475 and 5 gram of PEGMA360 monomers all charged in the reaction flask. Temperature was set at 701 C. The initial dosage of initiator was 0.4 grams of 0.5 wt. % APS aqueous solution. The second dosage of initiator included 1 gram of 0.5 wt. % APS aqueous solution.

Example 12

[0077] A brush polymer was made via the Synthesis Process, above, wherein the reactants were 178 grams of de-ionized water and 21 grams of methoxy(polyethlylene glycol).sub.17.05 methacrylate (MPEGMA750) monomer with 50 wt. % active all charged in the reaction flask. Temperature was set at 701 C. The initial dosage of initiator was 0.42 grams of 0.5 wt. % APS aqueous solution. The second dosage of initiator included 1.5 gram of 0.5 wt. % APS aqueous solution.

Example 13

[0078] A brush polymer was made via the Synthesis Process, above, wherein the reactants were 175 grams of de-ionized water and 20 grams of methoxypoly(ethylene glycol).sub.45.45 methacrylate (MPEGMA2000) monomer with 50 wt. % active were charged in the reaction flask. Temperature was set at 701 C. The initial dosage of initiator was 0.2 grams of 0.5 wt. % APS aqueous solution. The second dosage of initiator included 0.4 gram of 0.5 wt. % APS aqueous solution.

Example 14

[0079] A brush polymer was made via the Synthesis Process, above, except that a 1000 mL 4-neck round bottom flask was used, wherein in the process the reactants were 512.5 grams of de-ionized water and 29.5 grams of methoxypoly(ethylene glycol).sub.11.36 methacrylate (MPEGMA500) monomer all charged in the reaction flask. Temperature was set at 701 C. The initial dosage of initiator was 0.6 grams of 0.5 wt. % APS aqueous solution. The second dosage of initiator included 2 gram of 0.5 wt. % APS aqueous solution.

Example 15

[0080] A brush polymer was made via the Synthesis Process, above, wherein the reactants were 185 grams of de-ionized water, 0.6 gram of hydroxyethyl methacrylate (HEMA) and 9.4 grams of MPEGMA500 monomers all charged in the reaction flask. Temperature was set at 701 C. The initial dosage of initiator was 2 grams of 0.5 wt. % APS aqueous solution. The second dosage of initiator included 2 gram of 0.5 wt. % APS aqueous solution.

Example 16

[0081] A brush polymer was made in the same way as the polymer of Example 15, except that 1.5 gram of hydroxyethyl methacrylate (HEMA) and 8.6 grams of MPEGMA500 monomers were charged in the reaction flask.

Example 17

[0082] A brush polymer was made in the same way as in Example 15, except that 2.8 gram of HEMA and 7.2 grams of MPEGMA500 monomers were charged in the reaction flask.

[0083] The resulting polymers in synthesis Examples 1-17 were evaluated to determine their weight average molecular weight (GPC) and, viscosity, PL and Rg, as follows:

[0084] Persistence Length or (PL) and Radius of Gyration (Rg):

[0085] For a given polymer, the PL was determined based on the Kratky-Porod (KP) polymer chain model, by estimating from a non-linear least square curve fitting of a Rg (y axis) vs. an absolute MW (x axis) curve obtained by GPC including MALS using the following equation derived from the Kratky-Porod chain model (see T. Mourey, K. Le, T. Bryan, S. Zheng, G. Bennett Polymer 2005, 46, 9033-9042):

R.sub.g.sup.2=L.sub.p*M/3M.sub.LL.sub.p.sup.2+2L.sub.p.sup.3*M.sub.L/M2L.sub.p.sup.4*M.sub.L.sup.2(1e(M/(L.sub.p*M.sub.L))/M.sup.2

[0086] In the above equation, e is a natural log base; * represents a multiplier operator; Lp is the persistence length (PL); M is the absolute MW; M.sub.L is the molar mass per unit contour length. Assuming that the polymer has a homogeneous composition, M.sub.L was obtained from the repeat unit structure for the given polymer. Finally, the reported Lp was taken from the best fit of the Rg (y-axis) vs. MW (x-axis) curve with fixed M.sub.L by minimizing the sum of the square of the (log(Rg.sub.measured)log(Rg.sub.fitted)) on all data points from the Rg vs. MW curve.

TABLE-US-00001 TABLE 1 Analytical Data on Nonionic Brush Polymers Absolute Mw Degree of Rg Estimated Example Description (kg/mol) polymerization (nm) PL (nm) 1 MPEGMA475 770 1600 45 5.9 polymer 2 MPEGMA475 2800 5900 75 6.5 polymer 3 MPEGMA475 5700 12000 155 7.9 polymer 4 MPEGMA750 12300 16400 205 12.8 polymer 5 MPEGMA475-co- 770 1900 45 5.0 PEGMA360 CE 1 HPMC.sup.1 control 740 1900 130 12.6 CE 2 PEO polymer 190 4300 40 1.3 .sup.1Methocel F75M hydroxypropyl methyl cellulose ether (HPMC) (The Dow Chemical Co., Midland, MI).

[0087] As shown in Table 1, above, brush PEGMA polymers with a similar degree of polymerization as of hydroxypropyl methyl cellulose (HPMC) in Comparative Example CE1 have an acceptably high persistence length (>5 nm) and, by comparison, a much higher PL than the CCO backbone polyethylene oxide (PEO) polymers in Example CE2 that have a number of 1 nm.

[0088] Solution Viscosity:

[0089] Viscosity and shear thinning behavior of a 1.5 wt. % polymer aqueous solution was measured at 25 C. on using an Anton Paar MCR 301 viscometer (Anton Paar USA, Ashland, Va.) equipped with a high-throughput automated system. Polymers were dissolved in the indicated concentrations with stirring until the solution became homogeneous in DI water. Viscosity data was collected at a shear range increasing from 0.1 to 400 Hz. Acceptable shear viscosity at 0.5 Hz is anything above 1000 cP, preferably, 2500 cP or higher. Acceptable shear viscosity at 5 Hz is anything above 300 cP, preferably, 500 cP or higher.

[0090] As shown in the Table 2, below, the polymers of the present invention gave room temperature shear viscosities as a 1.5 wt. % polymer aqueous solution comparable to cellulose ethers especially, the crosslinked polymers of Examples 9-10 which had a molecular weight well into the preferred range. The polymer of Example 8, although crosslinked, was made with a thermal bis-nitrile which is not a preferred thermal initiator; and resulted in a lower product brush polymer molecular weight. The Example 6 polymer had a very high molecular weight as a result of using a high 0.1 wt. % of a persulfate initiator in polymerization. The polymer of Example 11 comprised a particularly preferred combination of PEGMA and MPEGMA, each having from 7 to 11 ethylene glycol groups in the side chain of the macromonomer; and the polymer had a molecular weight similar to crosslinked brush polymers.

TABLE-US-00002 TABLE 2 Solution Viscosities Shear Shear viscosity viscosity at 0.5 Hz at 5.0 Hz Relative Example (cP) (cP) Comment MW CE 1.sup.1 10258 4269 HPMC 710 6 2265 388 MPEGMA475 polymer 7 43 35 MPEGMA475 polymer 2320 8 24 24 MPEGMA475 polymer 2430 crosslinked 9 3067 618 MPEGMA475 polymer crosslinked 10 5865 912 MPEGMA475 polymer crosslinked 11 2135 514 PEGMA360:MPEGMA475 copolymer 12 15 15 MPEGMA750 polymer 1660 13 9 5 MPEGMA2000 polymer 1070 14 147 110 MPEGMA500 polymer 2240 15* 16 15 94PEGMA500/6HEMA 1870 16* 14 14 85PEGMA500/15HEMA 1630 17* 17 13 72PEGMA500/28HEMA 350 *Solution viscosities of Examples 15-17 were measured on a Rheometrics Fluids Spectrometer 2, described below; .sup.1Methocel F75M hydroxypropyl methyl cellulose ether (HPMC) (The Dow Chemical Co., Midland, MI).

[0091] The inventive polymers were further analyzed, as follows:

[0092] Dynamic Viscosity:

[0093] Measurements of aqueous polymer solutions having a concentration of 1.5 wt. % polymer were performed on a Rheometrics Fluids Spectrometer 2 (RFS-2) (Rheometrics, Inc., Piscataway N.J.) using the 50 mm diameter parallel plate fixture at 25 C. Strain sweeps were conducted to determine a linear viscoelastic regime. Because each Example gave different viscosities, various strain amplitudes were used to optimize the torque signal to stay within operation limits of the transducers and enable testing in the linear viscoelastic regime. Then, the samples were tested in a dynamic frequency sweep mode from 0.1 rad/s (radians/second) to 100 rad/s in eight equally spaced logarithmic increments per decade of frequency. The dynamic viscosity was recorded as a function of shear frequency and the value at selected frequencies is plotted in Table 3, below.

TABLE-US-00003 TABLE 3 Rheology of Polymers dynamic dynamic dynamic viscosity at viscosity viscosity at 0.1 rad/s (Pa at 1 10 rad/s (Pa Example s) rad/s (Pa s) s) CE1.sup.1 12.4 8.1 3.8 1 0.0036 0.0016 0.0013 2 0.0027 0.0024 0.0024 6 11.8 1.5 0.26 7 0.032 0.030 0.025 9 18.6 2.7 0.52 10 39.4 5.0 0.76 11 13.3 2.1 0.49 15 0.024 0.015 0.013 16 0.021 0.013 0.011 17 0.027 0.013 0.0096 .sup.1Methocel F75M cellulose ether (HPMC, Dow).

[0094] As shown in Table 3, above, the polymers of the present invention in Examples 6 and 9, 10 and 11, within the most preferred range of weight average molecular weight exhibit both thickening and shear thinning like that of a cellulose ether, Methocel F75M hydroxypropyl methyl cellulose ether (HPMC) of Example CE1.

[0095] Application Testing:

[0096] In a CBTA mortar formulation from Table 4, below, the polymers of the present invention gave a mortar consistency and water retention similar to that of Methocel F75M cellulose ether. And cement setting rate is significantly less reduced. Performance was tested in this mortar formulation for water retention capability (according to DIN 18555-7:1987-11 (1987) Deutsches Institut fr Normung, Beuth Verlag GmbH, Berlin, Del.) and setting behaviour (according to DIN EN 196-3:2009-2, 2009, Beuth Verlag GmbH), wherein one inserts a pin into mortar, measuring the beginning (begin) when insertion into the mortar becomes difficult, and measuring the ending (end) as when the pin cannot be inserted. Results are shown in Table 5, below.

[0097] Acceptable water retention % is 90% or higher, preferably, 93% or higher.

TABLE-US-00004 TABLE 4 Mortar Formulation Part Material Identity (wt. %) Cement OPC CEM I 42,5R Holcim PUR4, 30.0 Hamburg, DE Sand I Quarzsand F32 (Quarzwerke 34.8 Frechen, Frechen, DE) Sand II Quarzsand F36 (Quarzwerke 34.8 Frechen, Frechen, DE) Polymer Indicated in Table 5 0.4

TABLE-US-00005 TABLE 5 Mortar Performance Example C3.sup.2 CE1.sup.1 6 7 8 9 10 11 14 15 16 17 water retention (%) 73.3 98.1 92.2 91.6 86.9 93.3 92.7 94.0 97.3 93.2 93.2 92.0 setting (min) begin 223 614 364 370 394 340 365 311 429 End 488 814 525 540 538 496 467 429 567 duration 265 200 161 170 144 156 102 118 138 .sup.1Methocel F75M HPMC cellulose ether, (Dow, Midland, MI); .sup.2No thickener additive

[0098] The performance of the inventive Examples in mortar in Table 5, above, shows that the nonionic brush polymers of the present invention in Examples 6-7, 9-11 and 14-17 thicken nearly as efficiently as the cellulose ether and do so acceptably well. The Example 8 polymer was made with a non-preferred initiator and had a lower product brush polymer molecular weight compared to the same polymer made with the same amount of preferred peracids. Table 5 also shows that in comparison to the cellulose ether of Example CE1, the inventive polymers of Examples 6-11 and 14 did not retard setting as much as did the cellulose ether.