Emulsion PCE copolymers and use as water reduction agents

Abstract

The present disclosure relates to poly(carboxylate ether) copolymers are made in an emulsion polymerization and comprises repeating units derived from certain monomers. The PCE copolymer has a comb structure with an acidic polymer backbone linked to a plurality of pendant PEG side chains. The weight average molecular weight (Mw) of the poly(carboxylic acid) polymer that is produced when ester linkages in the PCE copolymer are fully hydrolyzed is at most 100 kg / mol. The PCE copolymer can be useful as a water reduction agent in mortars, concrete and the like.

Description

[0001] EMULSION PCE COPOLYMERS AND USE AS WATER REDUCTION AGENTS

[0002] FIELD

[0003] This application relates to the field of concrete, mortar, grout and stucco.

[0004] INTRODUCTION

[0005] Mortar, grout, stucco and sometimes concrete (called cementitious mixtures) are typically prepared in two stages. First, a dry mix that contains cement, filler and solid particulate additives (“dry components”) is blended together. Second, water is added to the dry mix to make a wet mix, which can be further formulated into the final cementitious mixture. The dry mix is stable as long as it remains sufficiently dry; it can be stored for long periods and transported easily. The wet mix starts to cure after the water is added and must be used before it becomes unworkable. (In the case of concrete, sometimes the aggregate filler is mixed with water first and then other components are added to make the wet mix.)

[0006] The major components of the dry mix are filler and cement. The dry mix components may also include small quantities of other additives, such as water reduction aids, organic binders, cellulose ethers, starch ethers, fibers, air entrainment agents, curing accelerators, curing retarders, defoamers and pigments.

[0007] The quantity of water added to make the wet mix is chosen to provide a workable viscosity. The viscosity of mortar, grout and stucco wet mix should allow it to spread smoothly on a substrate without dripping and allow the cementitious mixture to conform and adhere to tiles or other materials pressed onto it. The viscosity of concrete should allow it to fill molds and forms and (if needed) to be leveled into a smooth surface. Viscosity of a wet-mix is measured by slump - the extent to which a cone of wetmix spreads when support is removed.

[0008] Water-reduction agents (also known as plasticizers, superplasticizers or slump aids) allow the cementitious mixture to maintain a workable viscosity with less water. They are used to reduce the portion of water in the wet-mix, because wet-mixes that contain less water are denser and form a stronger cured concrete or mortar. The quantity of water is measured by the density of the wet mix; higher density indicates less water. Common types of water-reduction agents include lignosulfonates, naphthalene sulfonate formaldehyde polymers, and poly(carboxylate ether) copolymers.

[0009] Poly(carboxylate ether) copolymers (PCE copolymers) provide excellent water-cement ratios in cementitious mixtures with good workability, reduced segregation, and improved surface finishes. PCE copolymers comprise a backbone polymer chain which is a polycarboxylic acid (an acidic polymer). A plurality of pendent polyethylene glycol (PEG) polymer or oligomer chains are bonded to the backbone polymer by ester linkages. The structure is often called a “comb” structure and illustrated with the acidic polymer like the spine of a comb and the pendant PEG chains attached to the backbone like the teeth of a comb.

[0010] Processes to make PCE copolymers are inefficient and expensive. Some PCE copolymers are made by solution copolymerization of unsaturated polyethylene glycol-containing monomers (such as polyethylene glycol methacrylate or PEGMA) with unsaturated carboxylic acid-containing monomers (such as methacrylic acid) in an aqueous medium. Some of the monomers have low solubility in the aqueous polymerization medium, so only low solids content can be achieved. Further, the solution polymerization typically results in highly viscous reaction mixtures that become difficult to maintain agitation or further process once the mix is cooled. Excess water, glycol, or solvent may be added to reduce viscosity, but highly dilute solutions are inefficient to move, store or recover the PCE copolymer from.

[0011] Some PCE copolymers are made by grafting hydroxyl-terminated polyethylene glycol polymers onto the acidic polymer using an esterification reaction. The esterification reaction has high operating costs. Further, the esterification reaction rarely consumes all of the polyethylene glycol, and the residual polyethylene glycol is difficult to separate from the PCE product.

[0012] It would be desirable to provide more efficient processes to make PCE copolymers, and especially to make PCE copolymers that have improved performance as water-reduction agents.

[0013] SUMMARY

[0014] One aspect of this invention is a poly (carboxylate ether) (PCE) copolymer that comprises repeating units derived from:

[0015] (a) from 10 to 60 weight percent (wt%) of (meth)acrylic acid monomers;

[0016] (b) from 30 to 70 wt% of alkyl (meth)acrylate monomers wherein the alkyl moiety comprises on average from 1 to 3.5 carbon atoms; and

[0017] (c) from 5 to 40 wt% of PEG monomers, which each independently contain:

[0018] (i) a (meth)acrylate moiety linked by an ester linkage to

[0019] (ii) a polyethylene glycol moiety that contains on average more than 1 ethylene oxide unit; and

[0020] (iii) an end moiety linked to the polyethylene glycol moiety at the opposite end from the (meth)acrylate moiety, which is selected from hydrogen or an alkyl moiety; and

[0021] (d) From 0 to 20 wt% of other ethylenically unsaturated comonomers (“other comonomers”), wherein (i) the weight percentages are based on the total weight of the PCE copolymer, (ii) the PCE copolymer has a comb structure comprising an acidic polymer backbone linked to a plurality of pendant polyethylene glycol side chains; and (iii) the weight average molecular weight (M„) of the poly(carboxylic acid) polymer that is produced when ester linkages in the PCE copolymer are fully hydrolyzed (called a “hydrolysis product polymer” or “HPP”) is at most 100 kg / mol.

[0022] A second aspect of this invention is a process to make a poly(carboxylate ether) (PCE) copolymer comprising the step of performing an emulsion polymerization of:

[0023] (a) from 10 to 60 wt% of (meth)acrylic acid monomers;

[0024] (b) from 30 to 70 wt% or alkyl (meth)acrylate monomers wherein the alkyl moiety comprises on average from 1 to 3.5 carbon atoms; and (c) from 5 to 40 wt% of PEG monomers, which each independently contain:

[0025] (i) a (meth)acrylate moiety linked by an ester linkage to

[0026] (ii) a polyethylene glycol moiety that contains on average more than 1 ethylene oxide unit, and

[0027] (iii) an end moiety linked to the polyethylene glycol moiety at the opposite end from the (meth) acrylate moiety, which is selected from hydrogen or an alkyl moiety; and

[0028] (d) from 0 to 20 wt% of other comonomers, in an aqueous medium that contains an emulsifying quantity of surfactant and a polymerization initiator, under conditions suitable to produce a PCE copolymer that has a comb structure comprising an acidic polymer backbone linked to a plurality of pendant polyethylene glycol side chains, in which the weight average molecular weight (Mw) of the poly(carboxylic acid) polymer that is produced when ester linkages in the PCE copolymer are fully hydrolyzed (called a “hydrolysis product polymer” or “HPP”) is at most 100 kg / mol, wherein weight percentages are based on the total weight of monomers.

[0029] A third aspect of this invention is an aqueous dispersion comprising polymer particles suspended in an aqueous medium, wherein the polymer particles comprise a PCE copolymer as described in the first aspect of the invention.

[0030] A fourth aspect of this invention is a cementitious mixture comprising the following dry components (a)-(c):

[0031] (a) filler;

[0032] (b) cement;

[0033] (c) at least 0.01 wt% of a PCE copolymer as described in the first aspect of the invention, based on the total weight of the dry components; and optionally further comprising water.

[0034] A fifth aspect of this invention is a cured cementitious mixture comprising:

[0035] (a) filler;

[0036] (b) cured cement; and

[0037] (c) a PCE copolymer as described in the first aspect of the invention or its hydrolysis products.

[0038] PCE copolymers of this invention can be made simply and inexpensively with consistent properties by ordinary emulsion polymerization. Emulsion polymerization can use a high loading of monomers and produce an aqueous dispersion that contains a high loading of PCE copolymers. The aqueous dispersion may be efficiently used to deliver the PCE copolymer into cementitious mixture as a water-reducing agent, or it may be efficiently spray dried to make a powder. Some of the PCE copolymers may exhibit superior slump performance, as compared to PCE copolymers made by conventional processes. DETAILED DESCRIPTION

[0039] PCE copolymers and their Syntheses

[0040] This invention relates to a PCE copolymer. In an acidic environment, the PCE copolymer can exist in a dispersion wherein the PCE copolymer is contained within dispersed particles suspended in an aqueous medium. In a basic environment, the acid moieties in the PCE copolymer are ionized, and the PCE copolymer swells and can dissolve into the aqueous phase. Depending on the concentration of dissolved polymer, the viscosity of the aqueous phase may increase.

[0041] For the purposes of this document, “(meth) acrylic acid” refers to either acrylic acid or methacrylic acid or a mixture of both acrylic acid and methacrylic acid. In some embodiments, (meth)acrylic acid monomers consist essentially of acrylic acid. In some embodiments, (meth)acrylic acid monomers consist essentially of methacrylic acid. In some embodiments, (meth)acrylic acid monomers are a mixture comprising acrylic acid and methacrylic acid, in which methacrylic acid makes up at least 10 wt% of the mixture or at least 20 wt% or at least 30 wt% or at least 40 wt% or at least 50 wt% or at least 60 wt% or at least 70 wt% or at least 80 wt% or at least 90 wt%. In some embodiments, (mcth)acrylic acid monomers arc a mixture comprising acrylic acid and methacrylic acid, in which acrylic acid makes up at least 10 wt% of the mixture or at least 20 wt% or at least 30 wt% or at least 40 wt% or at least 50 wt% or at least 60 wt% or at least 70 wt% or at least 80 wt% or at least 90 wt%. In some embodiments, (meth)acrylic acid monomers may further contain small amounts of other alkyl acrylic acids such as ethacrylic acid; in some embodiments, the concentration of other alkyl acrylic acids is at most 10 wt% or at most 5 wt% or at most 2 wt% or at most 1 wt% or essentially 0 wt% (no measurable concentration).

[0042] Like (meth)acrylic acid, “(meth)acrylate” refers to either acrylate or methacrylate or a mixture of both acrylate and methacrylate. (Meth)acrylate monomers can have the equivalent embodiments to the embodiments stated for (meth)acrylic acid monomers, and may contain small amounts of other alkyl acrylates.

[0043] For the purpose of this document, “polyethylene glycol” or “PEG” refers to an oligomer or polymer that contains on average more than one repeating ethylene oxide unit. Some embodiments of PEG moieties can be represented by the Formula:

[0044] -(CR3H-CH2-O-)„- wherein “n” represents a number of alkylene oxide units (CHR3-CH2-O-), and each R3is individually hydrogen or a lower alkyl group. In the PEG moiety, more than 50 mole percent of alkylene oxide units are ethylene oxide, and R3contains on average less than 0.5 carbon atoms. In some embodiments, R3contains on average at most 0.3 carbon atoms or at most 0.2 carbon atoms or at most 0.1 carbon atoms or at most 0.05 carbon atoms or at most 0.02 carbon atoms or 0.00 carbon atoms. In some embodiments, at least 70 mole percent of the alkylene oxide units in the PEG moiety are ethylene oxide units or at least 80 mole percent or at least 90 mole percent or at least 95 mole percent or at least 98 mole percent. In some embodiments, 100 mole percent of the repeating units in the PEG are ethylene oxide units. In some embodiments, alkylene oxide units other than ethylene oxide units are selected from propylene oxide or butylene oxide units.

[0045] In some embodiments, the PEG contains on average at least 2 alkylene oxide units or at least 4 alkylene oxide units or at least 5 alkylene oxide units or at least 7 alkylene oxide units or at least 9 alkylene oxide units or at least 10 alkylene oxide units or at least 12 alkylene oxide units or at least 13 alkylene oxide units or at least 15 alkylene oxide units or at least 17 alkylene oxide units or at least 19 alkylene oxide units. In some embodiments, the PEG contains on average at most 50 alkylene oxide units or at most 45 alkylene oxide units or at most 40 alkylene oxide units or at most 30 alkylene oxide units or at most 25 alkylene oxide units or at most 23 alkylene oxide units or at most 20 alkylene oxide units. Embodiments of the number “n” would reflect these embodiments.

[0046] The PCE copolymer contains from 10 to 60 wt% of repeating units derived from (meth)acrylic acid monomers, based on the total weight of the PCE copolymer. In some embodiments, the PCE copolymer contains at least 15 wt% repeating units derived from (meth)acrylic acid monomers or at least 18 wt% or at least 20 wt% or at least 22 wt% or at least 24 wt% or at least 25 wt% or at least 27 wt% or at least 28 wt% or at least 30 wt% or at least 32 wt% or at least 35 wt%. In some embodiments, the PCE copolymer contains at most 55 wt% repeating units derived from (meth)acrylic acid monomers, or at most 50 wt% or at most 48 wt% or at most 45 wt% or at most 43 wt% or at most 40 wt% . In some embodiments, the (meth)acrylic acid monomers comprise primarily (more than 50 wt%) methacrylic acid.

[0047] The PCE copolymer contains from 30 to 70 wt% repeating units derived from alkyl (meth)acrylate monomers, based on the total weight of the PCE copolymer. The alkyl (meth)acrylate monomers comprise an alkyl moiety linked by an ester moiety to a (meth) acrylate moiety. The alkyl moiety of the alkyl (meth)acrylate monomer comprises on average from 1.0 to 3.5 carbon atoms. The (meth)acrylate portion of the alkyl (meth)acrylate monomer has the description previously given.

[0048] In some embodiments, the alkyl moiety contains on average at most 3.2 carbon atoms or at most 3.0 carbon atoms or at most 2.8 carbon atoms or at most 2.6 carbon atoms or at most 2.4 carbon atoms or at most 2.2 carbon atoms or at most 2.0 carbon atoms. In some embodiments, the alkyl moiety contains on average at least 1.2 carbon atoms or at least 1.4 carbon atoms or at least 1.6 carbon atoms or at least 1.8 carbon atoms or at least 2.0 carbon atoms. In some embodiments, the alkyl moiety in at least 50 wt% of the alkyl (meth)acrylate monomers is selected from methyl and ethyl groups, or at least 60 wt% or at least 70 wt% or at least 80 wt% or at least 90 wt% or up to 100 wt%. In some embodiments, the alkyl moiety in at least 50 wt% of the alkyl (meth)acrylate monomers is an ethyl group, or at least 60 wt% or at least 70 wt% or at least 80 wt% or at least 90 wt% or up to 100 wt%. In some embodiments, alkyl moieties in a minority of the alkyl (meth)acrylate monomers may comprise 3 or more carbon atoms, such as propyl, butyl and hexyl groups. In some embodiments, the alkyl moiety in at most 50 wt% of the alkyl (meth)acrylate monomers contains 3 or more carbon atoms, or at most 40 wt% or at most 30 wt% or at most 20 wt% or at most 10 wt% or 0 wt%. Examples of suitable alkyl ( meth jacry late monomers include methyl acrylate, ethyl acrylate, methyl methacrylate and ethyl methacrylate. In some embodiments, the alkyl (meth)acrylate monomers comprise primarily (more than 50 wt%) ethyl acrylate or at least 60 wt% or at least 70 wt% or at least 80 wt% or at least 90 wt% or up to 100 wt%. In some embodiments, the alkyl (meth) acrylate monomers may comprise a mixture of alkyl (meth)acrylate monomers, and in some embodiments the alkyl (meth)acrylate monomers consist essentially of a single monomer.

[0049] In some embodiments, the PCE copolymer contains at least 32 wt% repeating units derived from alkyl (meth)acrylate monomers, or at least 34 wt% or at least 36 wt% or at least 38 wt%. In some embodiments, the PCE copolymer contains at most 65 wt% repeating units derived from alkyl (meth)acrylate monomers, or at most 60 wt% or at most 55 wt% or at most 52 wt% or at most 50 wt% or at most 48 wt% or at most 45 wt%.

[0050] The PCE copolymer contains from 5 to 40 wt% repeating units derived from a “PEG monomers,” based on the total weight of the PCE copolymer. The PEG monomers contain (i) a (meth)acrylate moiety linked by an ester linkage to (ii) a polyethylene glycol moiety that contains on average more than 1 ethylene oxide unit, and (iii) an end moiety linked to the polyethylene glycol moiety at the opposite end from the (meth)acrylate moiety, which is selected from hydrogen or an alkyl moiety. Formula 1 illustrates exemplary PEG monomers: wherein:

[0051] • each R1is independently hydrogen or an alkyl group selected such that R1comprises on average less than 2 carbon atoms;

[0052] • each R2is independently an end moiety selected from hydrogen or an alkyl group; and

[0053] • each R!is independently hydrogen or a lower alkyl group selected such that R3comprises on average less than 0.5 carbon atoms, as previously described;

[0054] • - CHR3-CH2O)n- is a polyethylene glycol moiety, as previously described, comprising n repeating alkylene oxide units, wherein n is on average greater than 1.

[0055] In some embodiments, the meth(acrylate) moiety of the PEG monomer comprises primarily (more than 50 wt%) an acrylate moiety (R1= H). In some embodiments, the meth(acrylate) moiety of the PEG monomer comprises primarily (more than 50 wt%) a methacrylate moiety (R1= -CH3). In some embodiments, R1comprises on average at most 1.2 carbon atoms or at most 1.0 carbon atoms or at most 0.8 carbon atoms or at most 0.6 carbon atoms or at most 0.4 carbon atoms or at most 0.2 carbon atoms. In some embodiments, R1comprises on average at least 0.2 carbon atoms or at least 0.4 carbon atoms or at least 0.6 carbon atoms or at least 0.8 carbon atoms or at least 1.0 carbon atoms.

[0056] Embodiments of the polyethylene glycol moiety, R3and n are previously described. The polyethylene glycol moiety of the PEG monomer is terminated by in an end moiety (R2) opposite the meth(acrylate) moiety. In some embodiments, the end moiety is a hydrogen atom (R2= H). In some embodiments, the end moiety is an alkyl group (R2= alkyl). Alkyl groups in the end moiety (R2) contain at least 1 carbon atom. In some embodiments, alkyl groups in the end moiety (R2) contain on average at most 24 carbon atoms or at most 22 carbon atoms or at most 20 carbon atoms or at most 18 carbon atoms or at most 16 carbon atoms. In some embodiments, alkyl groups in the end moiety (R2) are lower alkyl groups, meaning the alkyl groups contain on average less than 8 carbon atoms or at most 6 carbon atoms or at most 4 carbon atoms or at most 2 carbon atoms. In some embodiments, alkyl groups in the end moiety (R2) are fatty alkyl groups, meaning the alkyl groups contain on average at least 8 carbon atoms or at least 10 carbon atoms or at least 12 carbon atoms or at least 14 carbon atoms. In some embodiments, end caps on the PEG monomers contain a mixture of lower alkyl groups and fatty alkyl groups.

[0057] In some embodiments, PEG monomers are selected so that the monomer is moderately hydrophilic but also moderately lipophilic, and the monomer interacts with the oil phase during emulsion polymerization. In some embodiments, the PEG monomers arc selected such that the resulting PCE copolymer is insoluble in acidic aqueous media, but is soluble in basic aqueous media. PEG chains that contain little or no propylene oxide or butylene oxide units are generally hydrophilic. When the PEG monomer contains many alkylene oxide repeating units (such as when n is on average at least 10 or at least 15 or at least 20), then in some embodiments the PEG monomer can be made more lipophilic by having a fatty end group in R2and / or by incorporating propylene oxide or butylene oxide into the PEG chain. On the other hand, when the PEG monomer contains only a small number of alkylene oxide units (such as when n is on average at most 10 or at most 15 or at most 20), then in some embodiments the PEG chain contains little or no propylene oxide or butylene oxide, and / or the end moiety (R2) comprises hydrogen or a lower alkyl group.

[0058] In some embodiments, the PEG monomer has a number average molecular weight of at least 150 g / mol or at least 200 g / mol or at least 300 g / mol or at least 400 g / mol or at least 450 g / mol or at least 500 g / mol. In some embodiments, the PEG monomer has a number average molecular weight of at most 3000 g / mol or at most 2000 g / mol or at most 1000 g / mol or at most 900 g / mol or at most 800 g / mol or at most 750 g / mol.

[0059] In some embodiments, the PCE copolymer contains at least 6 wt% repeating units derived from PEG monomer, or at least 7 wt% or at least 10 wt% or at least 12 wt% or at least 13 wt%. In some embodiments, the PCE copolymer contains at most 38 wt% repeating units derived from PEG monomer, or at most 35 wt% or at most 30 wt% or at most 25 wt% or at most 20 wt% or at most 18 wt% or at most 16 wt% or at most 14 wt%.

[0060] The PCE copolymer may optionally contain from 0 to 20 wt% repeating units derived from other ethylenically unsaturated comonomers, based on the total weight of the PCE copolymer. Examples of suitable “other ethylenically unsaturated comonomers” include maleic acid, itaconic acid, styrene, vinyl acetate, vinyl alcohol, acrylonitrile, acrylamide, alkyl acrylamides, 2-acrylamido-2-methylpropane sulfonic acid, sodium styrenesulfonate, sodium vinylsulfonate, phosphoethyl methacrylate, and vinyl chloride. In some embodiments, the PCE copolymer contains at most 15 wt% repeating units derived from other comonomers, or at most 10 wt% or at most 5 wt% or at most 3 wt% or at most 2 wt%. In some embodiments, the PCE copolymer may contain essentially no repeating units derived from other comonomers (0 wt%).

[0061] Suitable (meth)acrylic acid monomers, alkyl (meth)acrylate monomers, PEG monomers and other comonomers are commercially available. PEG monomers can also be made by known processes, such as reaction of (meth)acryloyl chloride with polyethylene glycol as described in Lin-Gibson et al., “Synthesis and Characterization of PEG Dimethacrylates and Their Hydrogels” , 5(4) Biomacromolecules 1280-1287 (2004) and Takeshita et al., “Crystallization of graft copolymers 1. Graft Chains Miscible with Main Chains” 42 Polymer Journal 482-488 (2010).

[0062] In some embodiments, the PCE copolymer is a random copolymer. In some embodiments, the PCE copolymer is represented by Formula 2: wherein:

[0063] • each R is independently an alkyl group in a repeating unit derived from alkyl (meth)acrylate monomer, as previously described;

[0064] • each R1is independently hydrogen or an alkyl group as described above;

[0065] • each R2is independently hydrogen or an alkyl group at the end of a PEG moiety as previously described;

[0066] • -(CHR3-CH2O)n- is a PEG moiety, as previously described, comprising n repeating alkylene oxide units;

[0067] • each R3is independently hydrogen or a lower alkyl group as described above;

[0068] • each M is independently a substituent that is appropriate for other ethylenically unsaturated comonomers as previously described, such as a hydroxyl moiety, an amide moiety, an alkyl amide moiety, a nitrile moiety, a halide, an acetate moiety, an organosulfonate moiety or an organophosphate moiety;

[0069] • x represents a number of repeating units derived from (meth)acrylic acid monomer, representing on average from 10 to 60 wt% of the polymer;

[0070] • y represents a number of repeating units derived from alkyl (meth)acrylate monomer, representing on average from 30 to 70 wt% of the polymer; • z represents a number of repeating units derived from PEG monomer, representing on average from 5 to 40 wt% of the polymer;

[0071] • m represents a number of repeating units derived from other comonomers, which is on average from 0 to 20 wt% of the polymer; and

[0072] • terminal groups on the polymer backbone are not shown.

[0073] In some embodiments of Formula 2, the illustrated repeating units are randomly distributed within the polymer. Embodiments of R, R1, R2, R3, M, x, y, z, n and m are described above.

[0074] As illustrated in Formula 2, the PCE copolymer comprises a poly(carboxylic acid) polymer backbone (“acidic polymer backbone”). Pendant alkyl and polyethylene glycol (PEG) moictics arc linked to the acidic polymer backbone by ester linkages. This structure is sometimes referred to as a “comb” structure, as previously described.

[0075] As previously described, pendant alkyl and polyethylene glycol (PEG) moieties can be removed from the acidic polymer backbone of the PCE copolymer by hydrolysis to yield a poly(carboxylic acid) polymer, called the “hydrolysis product polymer” or “HPP.” An example of the HPP is illustrated in Formula 3: wherein x, y, z, m, M and R1correspond to the values in the PCE copolymer and terminal groups on the polymer backbone are not shown. The molecular weight profile of the HPP is expected to roughly equal the formula weight profile of the acidic polymer backbone in the PCE copolymer.

[0076] In some embodiments, the poly(carboxylic acid) polymer that is produced when ester linkages in the PCE copolymer are fully hydrolyzed (HPP) has a weight average molecular weight of at most 95 kg / mol or at most 90 kg / mol or at most 85 kg / mol or at most 80 kg / mol or at most 75 kg / mol or at most 70 kg / mol or at most 68 kg / mol or at most 65 kg / mol or at most 55 kg / mol or at most 50 kg / mol or at most 45 kg / mol or at most 40 kg / mol or at most 35 kg / mol or at most 30 kg / mol. In some embodiments, the HPP has a weight average molecular weight of at least 10 kg / mol or at least 12 kg / mol or at least 15 kg / mol or at least 18 kg / mol or at least 20 kg / mol. (Molecular weight data in this document refers to relative molecular weight. See the description of the Test Method for further information.)

[0077] In some embodiments, the HPP has a number average molecular weight (Mn) of at most 30 kg / mol or at most 25 kg / mol or at most 22 kg / mol or at most 20 kg / mol or at most 18 kg / mol or at most 15 kg / mol or at most 12 kg / mol or at most 10 kg / mol. In some embodiments, the HPP has a number average molecular weight (Mn) of at least 3 kg / mol or at least 4 kg / mol or at least 5 kg / mol or at least 6 kg / mol or at least 7 kg / mol. In some embodiments, the HPP has a dispersity (Mw / Mn) of at most 6.0 or at most 5.5 or at most 5.0 or at most 4.5 or at most 4.0 or at most 3.8 or at most 3.5 or at most 3.3. In some embodiments, the HPP has a dispersity (Mw / Mn) of at least 2.0 or at least 2.5 or at least 2.7 or at least 2.8 or at least 2.9.

[0078] In some embodiments, the growth of the acidic polymer backbone is limited in emulsion polymerization by using a chain transfer agent. In this case, at least one end of the acidic polymer backbone may be terminated by the residue of a chain transfer agent. For example, the PCE copolymer may comply with Formula 4: wherein A is a residue of a chain transfer agent, and all other moieties have the meaning defined for Formula 2. In some embodiments, A is represented by the formula (-S-R4) wherein R4comprises an aliphatic moiety. In some embodiments, R4is a hydrocarbyl moiety, such as an alkyl moiety. In some embodiments, R4comprises oxygen, such as a ketone, an alcohol, a carboxylic acid or a carboxylate ester moiety. In some embodiments, R4comprises at least 2 carbon atoms or at least 3 carbon atoms. In some embodiments, R4comprises at most 24 carbon atoms or at most 20 carbon atoms or at most 18 carbon atoms or at most 16 carbon atoms or at most 14 carbon atoms or at most 12 carbon atoms or at most 10 carbon atoms or at most 8 carbon atoms or at most 6 carbon atoms or at most 4 carbon atoms. In some embodiments, A is represented by the formula (-O-R4), -R4-X or simply R4, wherein R4has the description previously provided and X is a halogen such as chlorine or iodine.

[0079] In some embodiments, the monomers are selected such that the PCE copolymer is alkali-soluble, which means soluble in water with a pH of 10, as measured according to the Test Methods. Cementitious environments are alkaline. In some embodiments, the PCE copolymer dissolves in the cementitious environment. In some embodiments, the PCE copolymer has solubility of at least 1 g / 100 g in water with a pH of 10. In some embodiments, the PCE copolymer has solubility of at least 10 g / 100 g in water with a pH of 10, or at least 20 g / 100 g or at least 30 g / 100 g. The solubility limit of some PCE copolymers may be difficult to measure, because the viscosity of the solution increases with increasing concentration of PCE copolymer.

[0080] In some embodiments, the monomers are selected such that the resulting PCE copolymer can remain in a stable dispersion in an aqueous acidic environment, such as in water with a pH of at most 6.5 or at most 5.5 or at most 5.0 or at most 4.5 or at most 4.0 or at most 3.5 or at most 3.0. The ability to remain in a dispersion is impacted by the balance of hydrophilic and lipophilic moieties in the polymer. The selection and proportions of acid, acrylate and PEG monomers can impact the balance of hydrophilicity and lipophilicity of the PCE copolymer as previously described and its ability to remain in a stable dispersion.

[0081] The PCE copolymers of this invention are made by emulsion polymerization. Emulsion polymerization processes are well-known and described in numerous publications, such as Emulsion Polymerization of Acrylic Monomers, published by Rohm and Haas Company, (1966) which is available

[0082] Lovell et al, Fundamentals of Emulsion Polymerization, 21 Biomacromolecules 4396-4441 (2020); and Juaregui, Thesis: Synthesis and Optimization of Emulsion Polymers published by California Polytechnic State University, San Luis Obispo (2016).

[0083] Emulsion polymerization takes place in an aqueous medium, which contains surfactants that act as emulsifiers. The monomers and surfactant form a dispersed organic phase in the aqueous medium, and polymerization is initiated by a free radical initiator or a redox initiator. The selection and proportions of the monomers in the emulsion polymerization reflect their desired proportions in the resulting polymer, as previously described. In some embodiments, the monomer emulsion contains at least 15 wt% monomers or at least 20 wt% monomers or at least 30 wt% monomers or at least 40 wt% monomers or at least 50 wt% monomers or at least 60 wt% monomers, based on the total weight of the emulsion. In some embodiments, the monomer emulsion contains at most 70 wt% monomers or at most 60 wt% monomers or at most 50 wt% monomers, based on the total weight of the emulsion.

[0084] Examples of appropriate surfactants for use as emulsifiers are commercially available from The Dow Chemical Company under the DOWFAX™ and TRITON™ trademarks. See, for example “Solutions for Emulsion Polymerizations,” published by The Dow Chemical Company (2018). In some embodiments, the weight percent of emulsifiers to monomer is at least 0.1 wt% or at least 0.2 wt% or at least 0.5 wt% or at least 1.0 wt% or at least 1.5 wt%. In some embodiments, the weight ratio of emulsifiers to monomer is at most 3.0 wt% or at most 2.5 wt% or at most 2.0 wt%.

[0085] Initiators for emulsion polymerization are known and commercially available. In some embodiments, the initiator is a water soluble free radical initiator. Examples of free radical initiators include persulfate salts such as ammonium persulfate and sodium persulfate and water-soluble azo compounds such as 2,2'-azobis[2-methylpropionamidine] dihydrochloride and 4,4'-azobis[4- cyanovaleric] acid. In some embodiments, the weight ratio of initiator to monomers is at least 0.05 wt% or at least 0.1 wt% or at least 0.15 wt%. In some embodiments, the weight ratio of initiator to monomers is at most 1 wt% or at most 0.5 wt%.

[0086] The polymerization is carried out under conditions suitable to limit the growth of the acidic polymer backbone, as previously described. Known means to control chain growth include: use of a chain transfer agent, atom transfer radical polymerization (ATRP), reversible addition / fragmentation chain transfer polymerization (RAFT) or nitroxide-mediated polymerization. See, for example, Cunningham, “Living / Controlled Radical Polymerizations in Dispersed Phase Systems,” 27 Pro, Poly, Sci. 1039-1067 (2002) and “Sigma - Aldrich Controlled Radical Polymerization Guide,” published by Merck KGaA (2019).

[0087] In some embodiments, emulsion polymerization is performed in the presence of a chain transfer agent. Chain transfer agents and their use are well known. See for example K. Matyjaszewski & T. Davis, Handbook of Radical Polymerization. Ch. 12 “Control of Free Radical Polymerization by Chain Transfer Methods” 629-691 (2002). Examples of suitable chain transfer agents include thiols, disulfides, alcohols and halogenated alkyl compounds. In some embodiments, the chain transfer agent is represented by Formula 5:

[0088] (5) R4-SH wherein R4has the description previously given. Examples of suitable chain transfer agents are methyl mercaptopropionate, mercaptopropionic acid, butyl mercaptopropionate, 2-mercaptoethanol, octanethiol and dodecanethiol, which are commercially available.

[0089] The quantity of chain transfer agent is suitable to limit the growth of the acidic polymer backbone as previously described. In some embodiments, the reaction mixture comprises at least 0.2 wt % chain transfer agent, based on the total weight of monomers in the reaction mixture, or at least 0.4 wt% or at least 0.5 wt% or at least 0.6 wt% or at least 0.7 wt% or at least 0.8 wt% or at least 0.9 wt% or at least 1.0 wt%. In some embodiments, the reaction mixture comprises at most 5.0 wt % chain transfer agent, based on the total weight of monomers in the reaction mixture, or at most 4.0 wt% or at most 3.0 wt% or at most 2.0 wt% or at most 1.8 wt% or at most 1.6 wt% or at most 1.4 wt% or at most 1.2 wt%.

[0090] In some embodiments, the emulsion polymerization is carried out at a temperature of at least 30°C or at least 40°C at least 50°C or at least 60°C or at least 70°C or at least 75°C. In many embodiments, the emulsion polymerization is carried out at a temperature of at most 95°C or at most 90°C. Pressure is not critical, as long as the blend of water, emulsifiers and other ingredients is stable; in most embodiments, ambient pressure is convenient. In many embodiments, the reaction mixture is agitated to provide good mixing.

[0091] The result of the emulsion polymerization is a polymer dispersion, which contains particles of the PCE copolymer suspended in the aqueous solvent. In some embodiments, emulsifiers from the emulsion polymerization participate in stabilizing the dispersion. In some embodiments, the z-average diameter of the polymer particles is at least 50 nm or at least 70 nm or at least 90 nm. In some embodiments, the z- average particle diameter is at most 500 nm or at most 250 nm or at most 150 nm or at most 100 nm. In some embodiments, the dispersion is a colloidal dispersion.

[0092] In some embodiments, the aqueous dispersion that results from the polymerization may be modified, such as by adding water or other solvents, by adding dispersants or other additives, or by adding acids, bases or buffers to adjust the pH.

[0093] The aqueous medium in the aqueous dispersion comprises at least 50 wt% water, based on the weight of the aqueous medium. In some embodiments, the aqueous medium comprises at least 60 wt% water, based on the weight of the aqueous medium, or at least 70 wt% or at least 80 wt% or at least 90 wt% or at least 95 wt% or 100 wt%. Other components of the aqueous medium, if any, should be miscible with water and should not cause the PCE copolymer to dissolve in the acidic aqueous medium.

[0094] In some embodiments, the dispersion is stable at 25°C for at least 1 day or at least 1 week or at least 1 month or at least 2 months or at least 3 months or at least 6 months. In this context, “stable” means that the dispersion does not show visible phase separation, coalescence or agglomeration of particles.

[0095] In some embodiments, the dispersion has a pH of at most 6.5 or at most 6.0 or at most 5.5 or at most 5.0 or at most 4.5 or at most 4.0 or at most 3.5. In some embodiments, the dispersion has a pH of at least 2.0 or at least 2.5. Frequently, a higher pH can cause the PCE copolymer to dissolve and / or gel.

[0096] In some embodiments, the concentration of PCE copolymer in the polymer dispersion is at least 10 wt% or at least 15 wt% or at least 20 wt% or at least 25 wt% or at least 27 wt% or at least 29 wt%. In some embodiments, the concentration of PCE copolymer in the polymer dispersion is at most 50 wt% or at most 45 wt% or at most 40 wt%.

[0097] In some embodiments, the PCE copolymer may be stored and used as a polymer dispersion.

[0098] In some embodiments, the polymer dispersion may be spray -dried or freeze-dried to form a powder comprising the PCE copolymer. Spray -drying equipment is commercially available with instructions for its use, and spray-drying is described in many publications such as: Santos et al., “Spray Drying - A Overview”, available at: published by Bete Performance Spray Engineering at www.BETE.com; and More Swati et al, “Review on Spray Drying Technology” 4(2) IJPCBS 219-225 (2014). PCE copolymer powders may be easier to store and transport and may optionally be added to a dry mix before water is added.

[0099] Use as Water Reduction Agents

[0100] PCE copolymers of this invention may be used as water reduction agents in cementitious mixtures (dry mix or wet mix). Powders that contain the PCE copolymer may be added to the dry mix before water is added. Alternatively, powders or dispersions that contain the PCE copolymer may be added to the wet mix after water is added. Alternatively, powders or dispersions that contain the PCE copolymer may be added to water before the water is added to the dry mix.

[0101] The cementitious mixtures contain filler, cement and optionally other additives as dry components. (“Dry components” are any components of the cementitious mixture that are normally solid at up to 40°C and atmospheric pressure.)

[0102] Fillers for cementitious mixtures usually contain inorganic particles. The particle sizes of the filler vary depending on the intended use of the cementitious mixture. Mortar, grout and stucco fillers generally contain sand. US standards for masonry filler are listed in ASTM C144 and in AASHTO M 45-15 / ASTM C 144-11. Concrete fillers generally contain aggregate, a mixture of sand and gravel of various sizes. US standards for concrete aggregate filler are listed in ASTM C33 and AASHTO M 6 / M 80. See also, Kousmata et al., Design and Control of Concrete Mixtures, Chapter 6 “Aggregates for Concrete ' (2016). In some embodiments, the filler may also contain pozzolans such as fly ash, calcined kaolin, pumices, or fumed silica; pozzolans and their use in cementitious mixtures are well-known and described in US Patent 9181131B2. In some embodiments, the filler may also contain inorganic pigments such as titanium dioxide, other metal oxides or carbon black. In some embodiments, the filler may also contain organic fibers or particles.

[0103] In some embodiments, the cementitious mixture contains at least 50 wt% filler, based on the dry components and excluding water, or at least 60 wt% or at least 65 wt% or at least 70 wt%. In some embodiments, the cementitious mixture contains at most 85 wt% of filler, based on the dry components and excluding water, or at most 80 wt%. In some embodiments, the cementitious mixture contains at least 50 volume percent filler, based on the dry components and excluding water, or at least 55 volume percent or at least 60 volume percent. In some embodiments, the cementitious mixture contains at most 85 volume percent of filler, based on the dry components and excluding water, or at most 80 volume percent or at most 75 volume percent.

[0104] The ASTM recognizes five categories of cement: Type 1 (ordinary Portland cement); Type 2 (moderate sulfate resistant cement); Type 3 (rapid hardening cement), Type 4 (low heat cement) and Type 5 (high sulfate resistant cement). Blends and variations on these five categories are also available, such as Portland limestone cement (Type IL). Any of these cements, blends or variations may be used in the cementitious mixtures of this invention. In some embodiments, the cement is ordinary Portland cement. In some embodiments, the cement is a variation of ordinary Portland cement, known as white cement. In some embodiments, the cement is Portland limestone cement. In some embodiments, the cement is a more specialized cement, such as a high alumina cement or a calcium sulfoaluminate cement. Suitable cements are commercially available.

[0105] The cementitious mixture should contain enough cement to effectively bind the dry components together. In some embodiments, the cementitious mixture contains at least 15 wt% cement or at least 20 wt%, based on the dry components and excluding water. In some embodiments, the cementitious mixture contains at most 50 wt% cement or at most 40 wt% or at most 35 wt% or at most 30 wt%, based on the dry components and excluding water.

[0106] Examples of other additives that may optionally be included in the cementitious mixtures include water retention aids, starch ethers, rheology modifiers, air-entraining agents, accelerators, retarders and defoamers.

[0107] • Water retention aids, such as cellulose ethers, slow the separation of water out of the wet mix.

[0108] • Starch ethers, such as hydroxypropyl starch ether, can improve the anti-sagging and anti-slip performance of the wet mix, as well as lengthening open time and providing a smoother surface.

[0109] • Rheology modifiers, such as bentonite clay, organically-modified clay, attapulgite, fumed silica and precipitated calcium carbonate, can modify the viscosity and shear thinning behavior of the wet mix. • Air-entraining agents cause the formation of small air-bubbles in wet mix, which can improve the resilience of the cured mixture under freeze-thaw cycles. Air-entrainment agents are frequently surfactants.

[0110] • Accelerators speed the setting of the wet mix. They may be especially useful in cold-weather use. Examples of common accelerators include calcium nitrate, calcium nitrite, calcium formate and certain aluminum compounds.

[0111] • Retarders slow the setting time of the wet mix. Examples of common retarders include calcium, sodium and ammonium salts of lignosulfonic acid, hydroxycarboxylic acids, carbohydrates, lead oxides, zinc oxides, phosphates, borates and fluorates.

[0112] • Defoamers can reduce air-entrainment and voids in the wet mix. Examples of defoamers include mineral oils, polyglycols and polyethersiloxanes.

[0113] The foregoing additives are commercially available with instructions for their use.

[0114] In some embodiments, the cementitious mixture contains at most 10 wt% of the other additives or at most 5 wt% or at most 2 wt%, based on the dry components and excluding water. In some embodiments, the cementitious mixture contains no measurable content of the other additives (essentially 0 wt%) or at least 1 wt% or at least 2 wt%, based on the weight of dry components and excluding water. In some embodiments, the wet mix contains at least 10 ppm defoamer, based on the total weight of the wet mix, or at least 25 ppm or at least 40 ppm or at least 50 ppm. In some embodiments, the wet mix contains at most 500 ppm defoamer, based on the total weight of the wet mix, or at most 200 ppm or at most 100 ppm or at most 75 ppm.

[0115] The cementitious mixture contains the PCE copolymer of this invention in a quantity suitable to reduce the quantity of water needed to produce a wet mix with suitable workability. In some embodiments, the cementitious mixture contains at least 0.05 wt% PCE copolymer, based on the weight of the cement, or at least 0.08 wt% or at least 0.10 wt% or at least 0.1 wt% or at least 0.15 wt% or at least 0.2 wt% or at least 0.25 wt% or at least 0.3 wt%. In some embodiments, the cementitious mixture contains at most 1.0 wt% PCE copolymer, based on the total weight of the cement, or at most 0.8 wt% or most 0.6 wt% or most 0.5 wt% or most 0.4 wt% or most 0.3 wt%.

[0116] In some embodiments, some or all of the dry components are preblended to make a dry mix before the dry components are mixed with water to form a wet mix. In some embodiments, some of the dry components, particularly additives, may be omitted from the dry mix and cither may be added to the water before it is blended in to form the wet mix or may be added into the wet mix after it is formed.

[0117] To make the wet mix, water is blended with the dry components in a quantity sufficient to fully wet the dry components and provide a cementitious mixture that is homogeneous and has desirable workability and viscosity. The optimum quantity of water varies depending on the dry components and their intended use, and can be readily determined by experimentation. In some embodiments, the amount of water is at least 9 wt%, based on the total weight of the wet mix, or at least 10 wt% or at least 11 wt% or at least 12 wt%. In some embodiments, the amount of water is at most 30 wt%, based on the total weight of the wet mix, or at most 25 wt% or at most 22 wt% or at most 20 wt% or at most 18 wt% or at most 16 wt% or at most 15 wt% or at most 14 wt% or at most 13 wt% or at most 12 wt%.

[0118] In some embodiments, the wet mix containing the PCE copolymer requires at least 5 percent less water to achieve workable viscosity, as compared to an identical wet mix without a water reduction agent, or at least 8 percent less water or at least 10 percent less water or at least 12 percent less water or at least 15 percent less water or at least 20 percent less water or at least 25 percent less water or at least 30 percent less water.

[0119] In some embodiments, the slump of the wet mix immediately after it is made (To, as measured according to the Test Methods) is at least 25 mm more than the slump of a similar wet mix without the PCE copolymer or at least 30 mm more or at least 40 mm more or at least 50 mm more or at least 60 mm more or at least 70 mm more or at least 80 mm more or at least 90 mm more or at least 100 mm more. In some embodiments, the slump of the wet mix 30 minutes after it is made (T30, as measured according to the Test Methods) shows a similar improvement.

[0120] The wet mix may be used in any suitable application. For example:

[0121] • Concrete wet mix may be cured in molds or forms to make solid structures, such as pavement, pavers, floors, blocks, walls, pillars or other concrete articles.

[0122] • Mortar may hold bricks, blocks, tiles or other structural elements in place.

[0123] • Stucco may coat a wall or form a layer in an exterior insulation and finish (EIFS) system. After it is applied, the wet mix is permitted to dry and cure. The time needed to dry and cure varies significantly depending on the selection of dry components in the wet mix (such as choice of cement, accelerators and retarders), the quantity of water, the thickness of the application, and the temperature and humidity at which the drying and curing occur. In many embodiments, the cementitious mixture dries to the touch in a few hours or less, and can be weight-bearing in a day or two. On the other hand, curing to full strength may take many days.

[0124] After curing is complete, the cured cementitious mixture reflects the contents of the wet mix used to make it. The cured cementitious mixture contains filler, cured cement, optionally additives, and residual PCE copolymer of this invention or its reaction products. In some embodiments, the alkaline environment of the wet mix hydrolyzes ester linkages in the PCE copolymer and releases the PEG side chains. As a result, some or all of the PEG side chains may be stripped from the PCE copolymer. The liberated PEG polymer may migrate to other parts of the wet mix, and may become trapped there in the cured cementitious mixture. Likewise, some or all of the acidic polymer backbone may be partially or wholly stripped of side chains and comprise a higher level of pendant acid moictics than the original PCE copolymer.

[0125] Test Methods

[0126] Unless stated otherwise, measurements listed in this application are made using the following test methods:

[0127] Hydrolysis of PCE Copolymer to obtain HPP:

[0128] Samples of the PCE copolymers are hydrolyzed in a Parr Bomb 4749 acid digestion vessel to obtain the hydrolysis product polymer (HPP). Hydrolysis is performed by adding 0.50 g of PCE copolymer, 1 g of potassium hydroxide pellets, 0.25 g of DI water and 10 mL of ethanol to a Teflon cup. The Teflon cup containing the aforementioned materials is placed inside the acid digestion vessel, and the vessel is sealed according to manufacturer instructions. The sealed acid digestion vessel is placed in a 150°C oven for 3 days. The Teflon cup is then removed from the acid digestion vessel, and the supernatant is decanted. The solid HPP is collected from the bottom of the cup and rinsed with 10 mL of ethanol. The solid HPP is then ready for molecular weight profile analysis.

[0129] Molecular Weight of HPP: Molecular weight of the HPP is determined by size exclusion chromatography (SEC).

[0130] Samples of HPP solution are prepared. The HPP is mixed in a concentration of 2 mg / g in a buffered phosphate solution that contains 20mM of ( 1 : 1 NaHiPQi and NaiHPOi) in water having a pH of 7.0. The mixture is shaken on a mechanical shaker overnight at room temperature to fully dissolve the HPP. Next, the sample solution is filtered using 0.2um Target2 (Fisher) PVDF filters. The sample is visually inspected to ensure that no undissolved material is visible.

[0131] The HPP is separated into different molecular weight fractions using SEC on a Waters UPLC system having an isocratic pump, degasser, injector, column oven and RI detectors operated at 35°C. The UPLC system is equipped with a TOSOH Bioscience TSKgel G2500PWxl column and a TSKgel GMPWxl column (packed with 7 pm and 13 pm particles and with internal dimensions of 7.8 mm x 300 mm). The system is calibrated using polyacrylic acid sodium salts from American Polymer Standards Corporation. A 20 pL sample is injected and the flow rate of the mobile phase is held at a rate of l.Oml / min. The data is collected and processed using version 3 of Empower software (Waters, Milford, MA). (For clarity, molecular weights reported by this system are relative molecular weights, based on the poly acrylic acid sodium salt standards, and not absolute molecular weight.)

[0132] Examples

[0133] The following examples illustrate specific embodiments of the invention, but do not limit the broadest scope of the invention.

[0134] The materials in Table 1 are used for the Examples:

[0135] Table 1

[0136] 1 - Monomer la is a polyethylene glycol polymer containing on average 20 repeating ethylene glycol units, capped on one end by a methacrylate ester moiety and on the other end by a fatty aliphatic moiety containing on average from 16 to 18 carbon atoms.

[0137] 2 - Monomer lb is a polyethylene glycol polymer containing on average 23 repeating ethylene glycol units, capped on one end by a methacrylate ester moiety and on the other end by a fatty aliphatic moiety containing on average from 12 to 14 carbon atoms.

[0138] 3 - TDCC = The Dow Chemical Company.

[0139] Synthesis of Polymers

[0140] The monomers listed in Table 2 are emulsion polymerized according to the following process: SLS (12.60 g, 28 wt% aqueous solution) and water (579.38 g) are charged into a 3 L, 4-neck round bottom flask equipped with a water condenser, overhead stirrer and a thermocouple, placed under nitrogen and heated to 88 °C.

[0141] A monomer emulsion is prepared by mixing together SLS (8.40 g, 28 wt% aqueous solution) and water (195 g) in a glass jar at ambient temperature. The desired monomers as shown in Table 2 are added in the following order:

[0142] • acrylate monomer containing dissolved MMP,

[0143] • PEG Monomers,

[0144] • methacrylic acid monomer (MAA).

[0145] The weight ratio of monomers for each example is selected to reflect the proportions shown in Table 2, and the total mass of monomers is selected to provide a final PCE copolymer dispersion having the solids content in Table 2. A portion of the monomer emulsion (41.18 g) is added to the round bottom flask while stirring. Immediately after the monomer emulsion is added, a mixture of APS initiator (0.53 g in 11.25 g water) is added to the kettle, followed by a water rinse (3.75 g). At the exotherm peak, a solution of aqueous APS (0.23 g in 45 g of water) and the remainder of the monomer emulsions are added to the round bottom flask over 1.5 hours while the contents are maintained at 85 °C. After 1.5 hours, the monomer emulsion and APS vessels and feed lines are rinsed with water, and the reaction mixture is stirred for 5 min at 85 °C. An aqueous solution of APS (0.19 g in 48.75 g of water) is added over 15 min. The contents are cooled to 75 °C, and dilution water (15 g) was added.

[0146] Cooling is continued to 30 °C, and remaining free monomer in the round bottom flask is chased during cooling by addition of 0.15 wt% aqueous active ferrous sulfate heptahydrate (2.74 g), followed by addition of 70% aqueous t-butyl hydroperoxide (0.3 g diluted in 9.38g water) over 15 minutes and rinsed with water (1.88 g), concurrent with addition of isoascorbic acid (0.41 g in 9.38 g water) over 15 minutes, and rinsed with additional water (1.88 g). Then the t-butylhydroperoxide and isoascorbic acid additions were repeated one time as described above.

[0147] The final polymer dispersion is filtered successively through 100 mesh and 325 mesh screens. The approximate solids content of the polymer dispersion is shown in Table 2, and the polymer dispersion has a pH of 2.5 to 4. The particle sizes of polymer particles in the dispersion are measured as set out in the Test Methods. Results are shown in Table 2.

[0148] Hydrolysis of PCE Copolymer:

[0149] Samples of the PCE copolymers are hydrolyzed to HPP, and the molecular weight profile of the HPP is measured according to the Test Methods. Results are shown in Table 2.

[0150] Production of PCE Powder

[0151] Samples of dispersions in IE1, IE2, and CE3 are spray dried to produce PCE copolymer powder. The polymer dispersions are diluted to 15-20 wt% solids. The dilute dispersion is spray-dried using a GEA Mobile Miner spray dryer equipped with a two-fluid nozzle atomizer. The inlet and outlet temperatures are set at 120-125°C and 55-65°C, respectively. The nitrogen (Nj) pressure to the nozzle is set at 1 bar with 50% flow rate, equivalent to 6 kg / hr of air flow. The dilute polymer dispersion is introduced into the spray dryer by a peristaltic pump. The water content in the atomized droplet is rapidly vaporized by contact with hot N flow at the inlet temperature. The dried powder is then cooled to the outlet temperature. A cyclone in the spray dryer separates the dried polymer powder from the N2 flow in the cyclone. Residual powder is filtered before ventilation.

[0152] Samples of aqueous dispersions in IE3-IE9 and IE12-IE13 are freeze-dried to produce PCE copolymer powder. Each dispersion is placed in a -20°C freezer for 2 days and then placing them on a LABCONCO FreeZone 4.5L -50°C instrument for 3 days with the vacuum set to 0.01 Torr and the condenser set to -50 °C.

[0153] Mortar Production and Testing

[0154] Mortar formulations are made by mixing Type IL cement, sand, defoamer and water using a Kitchen Aid Mixer in 6 L vessels at 2000 g scale as per ASTM C305. The weight ratio of Type IL cement to sand is 1:3. The weight ratio of water to cement is 0.55, which yields a total water content in the mortar of 12 wt%. The quantity of defoamer added is 0.1 gram of defoamer.

[0155] A quantity of water reduction agent (either a polymer of this invention or a comparative listed in Table 3) is added to each mortar formulation as shown in Table 3. The density of each mortar is measured as set out in the Test Methods, and results are shown in Table 3. The slump of each mortar formulation is measured according to the Test Methods, both immediately after it is made and after 30 minutes rest time. For a control (Control 1), no water reduction agent is added to a mortar formulation. For a second control (Control 2), a commercial polycarboxylate ether water reduction agent (PCENEX 111) is added to a mortar formulation. Results are shown in Table 3.

Claims

CLAIMS:

1. An aqueous dispersion comprising polymer particles suspended in an aqueous medium, wherein the polymer particles comprise a poly(carboxylate ether) (“PCE”) copolymer that comprises repeating units derived from:(a) from 10 to 60 weight percent of (meth)acrylic acid monomers;(b) from 30 to 70 weight percent of alkyl (meth)acrylate monomers; and(c) from 5 to 40 weight percent of polyethylene glycol (“PEG”) monomers, which each independently contain:(i) a (meth) acrylate moiety linked by an ester linkage to(ii) a polyethylene glycol moiety that contains on average more than 1 ethylene oxide unit, and(iii) an end moiety linked to the polyethylene glycol moiety at the opposite end from the (meth)acrylate moiety, which is selected from hydrogen or an alkyl moiety; and(d) from 0 to 20 weight percent other comonomers, wherein (i) the weight percentages are based on the total weight of the PCE copolymer, (ii) the PCE copolymer has a comb structure comprising an acidic polymer backbone linked to a plurality of pendant polyethylene glycol side chains; and (iii) the weight average molecular weight (Mw) of the poly(carboxylic acid) polymer that is produced when ester linkages in the PCE copolymer are fully hydrolyzed (“HPP”) is at most 100 kg / mol.

2. The aqueous dispersion of Claim 1 wherein the PCE copolymer contains from 25 to 45 weight percent of repeating units derived from (meth)acrylic acid monomers.

3. The aqueous dispersion of Claim 1 wherein the PCE copolymer contains from 34 to 55 weight percent of repeating units derived from alkyl (meth)acrylate monomers in which the alkyl portion of repeating units derived from the alkyl (meth) acrylate monomers contains on average 1 to 3 carbon atoms.

4. The aqueous dispersion of Claim 1 wherein the PCE copolymer contains from 10 to 38 weight percent of repeating units derived from PEG monomer.

5. The aqueous dispersion of Claim 4 wherein the repeating units derived from PEG monomers in the PCE copolymer comprise on average from 4 to 15 ethylene glycol repeating units, and each end moiety comprises on average less than 8 carbon atoms.

6. The aqueous dispersion of Claim 4 wherein the repeating units derived from PEG monomers in the PCE copolymer comprise on average at least 15 ethylene glycol repeating units, and each end moiety comprises on average at least 8 carbon atoms.

7. The aqueous dispersion of Claim 1 wherein the PCE copolymer is a random copolymer.

8. The aqueous dispersion of Claim 1 wherein the PCE copolymer is represented by Formula 2:wherein:(a) each R is independently an alkyl group comprising on average from 1 to 3.5 carbon atoms:(b) each R1is independently hydrogen or an alkyl group selected such that R1comprises on average less than 2 carbon atoms;(c) each R2is independently hydrogen or an alkyl group;(d) -(CHR3-CH2O)n- is a polyethylene glycol moiety, as previously described, comprising n repeating alkylene oxide units;(e) each R3is independently hydrogen or a lower alkyl group;(f) each M is independently a hydroxyl moiety, an amide moiety, an alkyl amide moiety, a nitrile moiety, a halide, an acetate moiety, an organosulfonate moiety or an organophosphate moiety;(g) x represents a number of repeating units derived from (meth)acrylic acid monomer;(h) y represents a number of repeating units derived from alkyl (meth)acrylate monomer;(i) z represents a number of repeating units derived from PEG monomer;(j) m represents a number of repeating units derived from other comonomers; and(k) terminal groups on the polymer backbone are not shown.

9. The aqueous dispersion of Claim 8 wherein in Formula 2:(a) each R comprises on average from 1.5 to 2.5 carbon atoms;(b) each R1comprises on average at most 1.2 carbon atoms;(c) each R3comprises on average from 0.0 to 0.2 carbon atoms;(d) x corresponds to from 25 to 45 weight percent of repeating units derived from (meth) acrylic acid monomers;(e) y corresponds to from 34 to 55 weight percent of repeating units derived from alkyl (meth) acrylate monomers;(f) z corresponds to from 10 to 38 weight percent of repeating units derived from PEG monomers;(g) m corresponds to from 0 to 2 weight percent of repeating units derived from other comonomers;(h) either (1) n is on average from 4 to 15, and R2comprises from 0 to less than 8 carbon atoms, or (2) n is on average at least 15, and R2comprises at least 8 carbon atoms; and(i) the repeating units are randomly distributed.

10. The aqueous dispersion of any one of Claims 1 to 9 wherein the HPP of the PCE copolymer has a weight average molecular weight (Mw) from 12 to 70 kg / mol.

11. The aqueous dispersion of Claim 10 wherein particles in the dispersion that contain PCE copolymer have Z-average particle diameter from 50 nm to 500 nm, and the aqueous dispersion contains from 15 to 50 weight percent PCE copolymer, based on the total weight of the aqueous dispersion.

12. The aqueous dispersion of Claim 10 wherein the dispersion has a pH from 2 to 6.

13. A process to make the aqueous dispersion of Claim 1 comprising the step of performing an emulsion polymerization of:(a) from 10 to 60 wt% of (meth)acrylic acid monomers;(b) from 30 to 70 wt% or alkyl (meth)acrylate monomers wherein the alkyl moiety comprises on average from 1 to 3.5 carbon atoms; and(c) from 5 to 40 wt% of PEG monomers, which each independently contain:(i) a (meth)acrylate moiety linked by an ester linkage to(ii) a polyethylene glycol moiety that contains on average more than 1 ethylene oxide unit; and(iii) an end moiety linked to the polyethylene glycol moiety at the opposite end from the (meth) acrylate moiety, which is selected from hydrogen or an alkyl moiety; and(d) from 0 to 20 wt% of other comonomers, in an aqueous medium that contains an emulsifying quantity of surfactant and a polymerization initiator, under conditions suitable to produce a PCE copolymer having a comb structure comprising an acidic polymer backbone linked to a plurality of pendant polyethylene glycol side chains, in which the weight average molecular weight (Mw) of polylcarboxylic acid) polymer that is produced when ester linkages in the PCE copolymer are fully hydrolyzed (HPP) is at most 100 kg / mol, wherein weight percentages are based on the total weight of monomers.

14. A cementitious mixture comprising dry components (i)-(iii):(i) filler;(ii) cement;(iii) at least 0.05 weight percent of the PCE copolymer or its hydrolysis products, based on the weight of the cement, and optionally further containing water, wherein the PCE copolymer comprises repeating units derived from:(a) from 10 to 60 weight percent of (meth)acrylic acid monomers;(b) from 30 to 70 weight percent of alkyl (meth)acrylate monomers; and(c) from 5 to 40 weight percent of polyethylene glycol (“PEG”) monomers, which each independently contain:(i) a (meth) acrylate moiety linked by an ester linkage to(ii) a polyethylene glycol moiety that contains on average more than 1 ethylene oxide unit, and(iii) an end moiety linked to the polyethylene glycol moiety at the opposite end from the (meth)acrylate moiety, which is selected from hydrogen or an alkyl moiety; and(d) from 0 to 20 weight percent other comonomers, wherein (i) the weight percentages are of (a), (b) and (c) are based on the total weight of the PCE copolymer, (ii) the PCE copolymer has a comb structure comprising an acidic polymer backbone linked to a plurality of pendant polyethylene glycol side chains; and (iii) the weight average molecular weight (Mw) of the poly(carboxylic acid) polymer that is produced when ester linkages in the PCE copolymer are fully hydrolyzed (“HPP”) is at most 100 kg / mol.

15. A poly(carboxylate ether) (PCE) copolymer that comprises repeating units derived from:(a) from 10 to 60 weight percent (wt%) of (meth)acrylic acid monomers;(b) from 30 to 70 wt% of alkyl (meth)acrylate monomers wherein the alkyl moiety comprises on average from 1 to 3.5 carbon atoms; and(c) from 5 to 40 wt% of PEG monomers, which each independently contain:(i) a (meth) acrylate moiety linked by an ester linkage to(ii) a polyethylene glycol moiety that contains on average more than 1 ethylene oxide unit; and(iii) an end moiety linked to the polyethylene glycol moiety at the opposite end from the (meth)acrylate moiety, which is selected from hydrogen or an alkyl moiety; and(d) from 0 to 20 wt% of other comonomers, wherein (i) the weight percentages are based on the total weight of the PCE copolymer, (ii) the PCE copolymer has a comb structure comprising an acidic polymer backbone linked to a plurality of pendant polyethylene glycol side chains; and (iii) the weight average molecular weight (Mw) of the polyfcarboxylic acid) polymer that is produced when ester linkages in the PCE copolymer are fully hydrolyzed (“HPP”) is at most 100 kg / mol.

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