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1. WO2000031172 - PARTICULES ATTACHEES A DES PREMIER ET SECOND POLYMERES A GROUPES ASSOCIATIFS MUTUELLEMENT NON COVALENTS

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[ EN ]

PARTICLES ATTACHED TO FIRST AND SECOND POLYMERS HAVING MUTUAL NON-COVALENTLY ASSOCIATIVE GROUPS

10
Inventors:
Felek Jachimowicz, Byong-Wa Chun, Shawn Williams,
Hideo Koyata, and Ara Jeknavorian

15 Field of the Invention
The present invention relates to a polymeric system for modifying the rheology or fluidity of an aqueous particle-containing environment, such as a cementitious composition.

20 Background of the Invention
More particularly, the present invention relates to a novel multi-component system of polymeric materials that operate to modify or control the rheology or flow properties of aqueous slurries or dispersed particulates.
The technology disclosed herein is believed to be useful for any industry

25 employing aqueous slurries or dispersions of particles, such as the paint, water treatment, ceramics, and electromagnetic recording materials industries. It is particularly appropriate for use in the cement and concrete industries and other industries in which the control of rheological or flowability properties and the stability of the particle slurry or dispersion are critical issues.
30 For inorganic slurries such as hydraulic cementitious compositions (e.g., concrete, mortar, and cement paste) which are perhaps the most complex examples of aqueous particle dispersions, it is known to use "superplasticizers" or water reducing agents to increase the strength of the hardened materials while maintaining workability of the material before it hardens. Such modification of these ultra

35 complex particle dispersions are realized by the effect of comb-type polymers on the surface charge or energy of the particle surfaces. It is was noted by K. Yoshioka et al., J. Am. Ceram. Soc , Vol. 80 (10), 2667 - 2671 (1997), that new comb-type polymers, such as poly-(carboxylic acid) type with graft chains (e.g., ethylene oxide maleic acid or ethylene oxide acrylic acid copolymers), have attracted great
„ i „ attention in the industry because of their superior performance in dispersing cement particles and maintaining concrete slump characteristics.
In such prior art poly-alkoxylate-containing carboxylate copolymers, the poly-alkoxyl groups are covalently bonded to the polycarboxylic chain. The optimum molecular structure of such cement superplasticizers, however, varies with conditions such as cement type and quality, water-to-cement ratio, temperature, and other factors. Performance requirements may also vary from time to time. The present inventors believe that existing technologies are incapable of dealing with these numerous variables using the present polymeric systems. Either performance is compromised or multiple admixtures are required. These shortcomings all work disadvantageously to undermine the economic justifications for using the conventional dispersing systems.
A novel composition and method for modifying the rheology or flow characteristics of aqueous slurries or particulate dispersions are therefore needed.

Summary of the Invention
In surmounting the difficulties of the prior art, the present invention provides a non-covalently-associated, in-situ rheology modifier complex for use in modifying the rheology (or flowability properties) of an aqueous particle-containing environment.
In other words, the modification or enhancement of the flowability of an aqueous slurry or dispersion of particles in an aqueous, such as in hydraulic cementitious compositions, is achieved by the formation of an in situ molecular complex formed by polymers or constituents that become non-covalently-associated or complexed with each other near or at the surface of the particle which is intended to be dispersed in the aqueous environment.
The non-covalently-associative complexes of the invention may be achieved, for example, by the use of fatty acid moeities located on components which, through mutual "hydrophobicity" in the aqueous environment, form an association or complex much in the way that micelles are formed by electrically charged colloidal particles. The term "in situ" is used to describe the formation of the dispersing complex outside of the factory, either in the mix water, in the slurry or dispersion (e.g., concrete), or in a storage tank. The present invention therefore represents a fundamental and startling departure from prior art "comb-type" superplasticizers, in which a polymer "backbone" or main chain (containing carboxylic acid or hydroxyl groups for surface attachment to cement particles) is grafted by covalent bonding to pendant "teeth" groups (containing poly(oxyalkylene) repeating units which function to disperse the calcium particles within the slurry).
Rather, the present invention provides greater "tunability" in that it is easier to select and combine the particle-attaching component/function with the particle-dispersing component/function, using a minimum number of components or process steps. Through their inventive and novel use of non-covalently-associative polymers or constituents to provide rheology-modifier complexes "in situ," the present inventors think it easier to design, test, evaluate, optimize, and implement different rheology modifier systems. This is done simply by adjusting the type and/or ratio of the polymer or constituent components and "zippering" the different components together.
An exemplary composition of the invention thus comprises a first polymer having components represented by the formula X'mY'n wherein component X' represents a particle-attaching group operative to attach to the surface of the particle to be dispersed within the aqueous environment. Thus, X' is a component, preferably a repeating unit, comprising at least one carbonyl group, carboxylate, carboxylic acid, hydroxyl group, hydroxylate or oxide, sulfonyl group, sulfate, sulfonate, phosphonyl group, phosphonate group, boronic acid or its derivatives, or an amine. Y' represents a first non-covalently-associative group that is covalently bonded to component X'; and "m" and "n" separately represent integers at least equal to 1. The invention further comprises a second polymer represented by the formula Y"Z' (or Y"Z'Y") wherein Y" is a second non-covalently-associative group which is complementary to the first non-covalently-associative group; and component Z' is a group operative to disperse the particle (when attached by X'Y') within the aqueous environment. The first and second polymer components, when incorporated into an aqueous particle-containing environment, form a non-covalent association or complex by mutual operation of the complementary first and second non-covalently-associative groups within the aqueous environment. This allows the resultant complex to attach to, as well as to disperse, particles within the slurry or dispersion. In other words, the particle-attaching and particle-dispersing functionalities become combined in a non-covalent manner. For example, the first and second non-covalently-associative groups comprise hydrophobic groups which are complementary to each other.
Exemplary processes for modifying the rheology or flowability property of an aqueous particulate-containing environment are also described herein. Exemplary particle-containing compositions, including cement and cement compositions, and methods for making them, are also disclosed hereinafter.

Brief Description of the Drawings
A comprehension of the following detailed description of exemplary embodiments may be facilitated by the accompanying drawings, wherein
Fig. 1 is a conceptual illustration of a prior art "comb-type" graft chain polymer molecule attached at the surface of a particle (e.g., cement) dispersed within an aqueous environment (e.g., cementitious slurry); and
Fig. 2 is a conceptual illustration of a rheology modifier of the present invention, which can be formed in situ through the use of non-covalently-associative groups attached to a particle-attaching group and a particle-dispersing group, at the surface of a particle (e.g., cement) dispersed within an aqueous environment (e.g., cementitious slurry).

Detailed Description of Exemplary Embodiments
The phrase "aqueous particle-containing environment" means and refers to particles or particulate matter that is dispersed, suspended, or dispersible or suspendible in, or otherwise contained in, water-based systems, such as are used for making paint formulations, priming compositions, surface coatings, or other surface treatment compositions, water treatment compositions (e.g., scaling control materials), ceramic materials, electromagnetic recording materials, patching compounds, crack and joint filler materials, and the like. The phrase includes aqueous slurries as well as dispersions of particulate matter.
While the present invention is believed to be suitable for use in a variety of applications, the present inventors will use cementitious compositions for illustrative purposes herein, because these compositions exemplify an extremely complex system which is difficult to control.
A suitable slurry contemplated for use in the invention thus includes hydraulic cementitious compositions which begin to harden upon the addition of mix water. The term "cement composition" as may be used herein refers to pastes, mortars, grouts such as oil well cementing grouts, and concrete compositions comprising a hydraulic cement binder. The terms "paste", "mortar" and "concrete" are terms of art: pastes are mixtures composed of a hydraulic cement binder (usually, but not exclusively, Portland cement. Masonry cement, or Mortar cement and may also include limestone, hydrated lime, fly ash, blast furnace slag, and silica fume or other materials commonly included in such cements) and water; mortars are pastes additionally including fine aggregate, and concretes are mortars additionally including coarse aggregate. The cement compositions tested in this invention are formed by mixing required amounts of certain materials, e.g., a hydraulic cement, water, and fine or coarse aggregate, as may be applicable to make the particular cement composition being formed.
The terms "non-covalently-associated", "non-covalently-associative," and "non-covalent association, " as well as variations thereof, are used herein to refer to groups or moieties on components which operate, when placed in the aqueous environment wherein particles are intended to be dispersed, to draw or bring the rheology-modifier components together to form a molecular complex wherein the functionality of particle-attachment and the functionality of particle-dispersing-ability are combined. These terms (e.g., "non-covalently-associated") are used in contradistinction to prior art "comb-type" superplasticizers which are formed by covalently bonding one molecule onto another to form covalent bonds, such as through copolymerization or grafting reactions.
An exemplary manner of achieving a non-covalent association is through the use of hydrophobic groups which cluster together, similar to the formation of micelles from charged colloidal particles, so as to form a molecular complex within the aqueous environment. While it is not intended that the present invention be confined by the theoretical concepts and illustrations herein, the present inventors believe that the concept of "hydrophobic association" is helpful for illustrating an exemplary mode of achieving and understanding the features, advantages, and performance of the invention.
Fig. 1 is a conceptual illustration, similar to that contained in the above-mentioned article of K. Yoshioka et al., J. Am. Ceram. Soc, Vol. 80 (10), 2667 -2671 (1997), of prior art comb-type superplasticizers, such as poly-(carboxylic acid) type polymers with graft chains of ethylene oxide maleic acid or ethylene oxide acrylic acid copolymers. The resultant molecular structure is said to be "comb- like" in that its main "backbone" polymer is grafted (covalently) to "teeth-like" pendant hydrophilic groups.
Fig. 2 is a conceptual illustration of an exemplary non-covalently-associated rheology modifier of the present invention. The polymer components of the invention may be understood conceptually to be non-covalently-associative in that the particle attachment group and particle dispersing group each are attached to non-covalently-associative groups, such as (for example) mutually hydrophobic groups, that tend to make them associate with each other or otherwise form a complex or interaction near or at the surface of the particle. It is surmised that non-covalently-associative groups (such as hydrophobic groups) tend to associate within the aqueous environment because their association represents the state of lowest energy within the aqueous matrix. The resultant complex, therefore, yokes together the particle-attaching aspect with the panicle-dispersing aspect without employing covalent bonds.
Thus, as shown in Fig. 2, an exemplary composition of the present invention comprises a first polymer having components represented by the formula X'mY'n. X' represents a component, preferably a repeating unit, that functions to attach to the particle to be dispersed. This component preferably has repeating units having at least one carbonyl group, carboxylate, carboxylic acid, hydroxyl group, hydroxylate or oxide, sulfonyl group, sulfate, sulfonate, phosphonyl group, phosphonate group, boronic acid or its derivatives, or an amine. For example, X' may comprise a quaternary ammonium salt if the particles to be suspended are clay particles. Y' represents a component, preferably a repeating unit, comprising a first non-covalently-associative group. The first polymer components X' and Y' are covalently bonded together and may be arranged in block order (e.g., -( X'X'X') -( Y'Y'Y')-), or, more preferably, in random order (e.g., -XΥ'X'X'Y'Y'-, -X'Y'X'Y'X'Y'-, etc.). The number of repeating units of X' and Y' are represented by "m" and "n," respectively, which separately are integers of at least 1. "m" is preferably an integer of 2-2000; while "n" is preferably an integer of 1-1000. The first polymer is conceptually illustrated in Fig. 2 and is illustrated as being attached at points to the surface of a particle (cement), while its non-covalently-associative components are illustrated as being in a non-covalent-association with the corresponding non-covalently-associative group of the second polymer, which has components represented by the formula Y"Z' (or it may be represented by the formula Y"Z'Y"). Y" represents a second non-covalently-associative group which is complementary to the first non-covalently-associative group (Y1) of the first polymer mentioned above. The complementary non-covalently-associative groups Y' and Y" are preferably identical or chemically-similar to each other, although they do not necessarily need to be. Preferably, both are comprised of repeating units. Z' represents a particle dispersing group that is covalently bonded to the second non-covalently-associative group Y" and is operative to disperse the attached particle within the aqueous environment. In Fig. 2, the Z' group is conceptually illustrated as being disposed away from the attached (cement) particle and outward into the aqueous surrounding environment (in the manner of micelle formation). Thus, the first and second polymers of the present invention form a non-covalently-associated complex within the aqueous environment, such as in a hydraulic cementitious composition, thereby combining a particle-attaching ability with a particle-dispersing ability.
Preferably, the first and second non-covalently-associative groups on the first and second polymers comprise hydrophobic groups such as fatty acids, which tend to cluster together in situ (e.g., forming a complex in the aqueous environment similar to soap micelles in water) to form the non-covalently bonded rheology modifier complexes of the present invention.
It will therefore be possible for the performance characteristics of the in-situ rheology modifier complexes of the present invention to be altered and modified by those of ordinary skill in view of the inventive teachings herein. The particle-attaching properties of the first polymer may be altered, for example, with respect to the nature of the particles to be dispersed (e.g., surface characteristics, particle size and morphology, type and density of ions or attachment points on the surface, etc.). The particle-dispersing properties of the second polymer may be altered, for example, with respect to the nature of the aqueous environment in which the particles are to be dispersed (e.g., quality of water, softness or hardness, presence or absence of surfactants or surface-active agents, etc.).

It is important that mixtures containing the exemplary components of the present invention be sufficiently blended together when in the aqueous environment such that the cement-particle-attaching group becomes associated physically with the particle-dispersing group (which may, for example, be a hydrophilic group), otherwise the enhanced dispersing effect of the invention will not be realized.
In an exemplary compositions of the invention, wherein the non-covalently-associative groups are hydrophobic groups, a preferred first polymer X'mY'n has the formula
-[CH2-CR'(COOM)]m - [CH2 - CR'R2],,-wherein R1 = hydrogen or -CH3. R2 = -I'-(OA)j-R3 wherein - I'- represents -COO-, -CONH-, -CH2O-, -O-, or mixture thereof; OA represents a C2 to C3 alkylene oxide repeating unit and "j" = 0 - 10; R3 represents an alkyl group, alkylphenyl group, or (OB')k group wherein OB' represents a C3 to C5 alkylene oxide repeating unit and "k" = 10-90; M = hydrogen, an alkali or alkaline earth metal, or ammonium ion; "m" = 1 - 2000; and "n" = 1 - 2000. Preferably, the ratio of "m" to "n" (m:n) is 100:1 to 3: 1. The exemplary second polymer component has the formula
R3-(AO)p-R' or R3-(AO)p-R3
wherein R3 represents an alkyl group, alkylphenyl group, or (OB' )k group wherein OB' represents a C3 to C5 alkylene oxide repeating unit and "k" = 10-90; AO represents a C2 to C3 alkylene oxide repeating unit and "p" =0-10; and R1 = hydrogen or -CH3. Preferably, the second polymer has the formula R3-(AO)p-R'.
Exemplary Y' and Y" (hydrophobic) groups may comprise C^-C20 alkyl groups, alkylaryl groups, or mixtures or derivatives thereof. Such groups, when bonded to respective X' and Z' groups are believed to provide suitable hydrophobicity when employed in aqueous environments such as cementitious slurries. Another type of hydrophobic group which is also believed suitable for use as Y' and Y" (hydrophobic) groups is represented by the formula R3SiO(SiR2O)n-SiR3 wherein R3 represents an alkyl group or alkylphenyl group, and "n" is an integer of 1-1000.
Exemplary Z' groups, which function to disperse the particles in the aqueous environment, preferably include oxyalkylene groups such as ethylene oxide groups ("EO"), polyethylene oxide groups ("PO"), or mixtures thereof (referred to as "EO/PO" groups). Among these, EO groups are preferred. If EO/PO mixtures are used, preferably the EO:PO ratio is at least 3:1. The Z' groups may preferably comprise hydrophilic groups, although it has been found that in some cases they may not necessarily be classified as "hydrophilic" (water-loving) in a technical sense, so long as they operate to disperse the particle within the aqueous matrix.
The manner of selecting and making the respective X'Y' polymers and Y"Z' or Y"Z'Y" polymers will be evident to those skilled in the art in view of the teachings herein. In the cement and concrete industries, for example, these polymer components may be derived from known cement-attaching groups, hydrophobic groups, and cement dispersing groups as may be known in the art. For example, some of these groups may be found in US 4,946,506 of Arfaei et al.; US 5,100,984 of Burge et al.; US 5,142,036 of Akimoto et al.; US 5.348,993 of Daeumer et al.; US 5,369,198 of Albrecht et al.; US 5,393,343 of Darwin et al.; US 5,476,885 of Tahara et al.; European EP 0 725 043 A2 of Akira Ohta et al.; and Canadian Patent Application 2,125,521 of Y. Tanaka et al., all of which are incorporated fully herein by reference. Thus, the inventors believe that it would be within the skill of those in the chemical arts to modify polymers containing particle-attaching groups or moieties as well as polymers containing particle dispersing groups or moieties, such that they will form the non-covalently-associated rheology modifier complexes of the present invention.
Preferably, the ratio of the first polymer to second polymer is 0.05 to 2.0 wt % (s/s cement), and more preferably 0.1 to 0.5 wt % (s/s cem).
An exemplary method of the invention for modifying the rheology of an aqueous particle-containing environment comprises combining the above-described exemplary dispersing composition with particles and mix water. The dispersing composition may be incorporated first into the aqueous environment before addition of the particles, or combined first with particles before they are introduced into the aqueous environment. The particles, dispersing composition, and water may also be mixed together simultaneously.
Further exemplary methods include, for example, incorporating one of the components (X'Y') first with the particles to be dispersed, and then incorporating the other component (Y"Z') into the mix water, such that non-covalently-associated complex X'Y'*Y"Z' is formed when the particles and mix water are combined.
For example, the first polymer component X'Y' may be introduced to cement particles during the manufacture of the cement, such as before and/or during the grinding stage; and then the second polymer component Y"Z' (or Y"Z'Y") may be introduced at a subsequent stage, when the cement particles (coated and/or intermixed with the polymer component X'Y') are combined with mix water to obtain a mortar or concrete. The second polymer Y"Z' may therefore be subsequently introduced during, after, or just before the mix water is to be combined with the cement particles. Thus, an exemplary method for modifying the rheology of a cementitious composition comprises introducing, during cement particle manufacture, said first component X'Y', and, at a subsequent time, introducing said second polymer component Y"Z' to the mix water during the formation of mortar or concrete.
The invention therefore covers these methods, compositions comprising particles (to be dispersed) and either one or both of the above-described X'Y' or Y"Z' components; as well as aqueous compositions comprising particles (to be dispersed) and either one or both of said X'Y' and Y"Z' components.
The invention may be more readily comprehended when the following examples are considered.

Example 1
Preparation of Exemplary First Polymer (Radical Polymerization)
A 10 g (0.14 mol) of acrylic acid was weighed into a 250 mL round-bottom flask that was then fitted with a mechanical stirrer, a reflux condenser, and a mtrogen supply. A sample, 4.2 g (0.0093 mol), of polyethylene glycol) 4-nonylphenyl ether acrylate was weighed in air and added to the reaction flask along with 50 mL of 2-propanol. A 0.73 g (0.007 mol) sample of mercaptopropionic acid was added, and the mixture was sparged (deoxygenated by displacement) with nitrogen. After 10 minutes of sparging, the mixture was put under a positive pressure of nitrogen and then heated to 60 °C with stirring. At this time, a sample of 2, 2'-azoisobutyronitrile (0.1 g) was added to the mixture. The mixture was refluxed for 3 hours and then allowed to cool to room temperature with stirring. The solvent was stripped by rotary evaporation and the resulting material was dissolved in water. The pH of this solution was adjusted to 6.9 by dropwise addition of aqueous sodium hydroxide (50 % w/w).
The reaction is summarized below:


Example 2
(Mortar testing)
A mortar mix containing 760 g of ordinary Portland cement with 1575 g of sand and 334 g of water was formulated. The admixture was pre-dissolved in the mixing water, 5 minutes before the test. In order to rid the mortar air, 0.5g of defoamer, tri-butylphosphate (TBP), was added to all mixes. The mortar was mixed for 5 minutes with a Hobart mixer, then slump was measured by placing the mortar mix into a cone and inverting the cone onto a table to cast a cone-shaped sample, and then measuring the drop in height of the cone. The cone size used was in accordance with JTS Al 173 (cone height = 150 mm; upper diameter = 50 mm; bottom diameter = 100 mm). At the same time, slump-flow (diameter of spread) was measured. Air content was measured by ASTM C185 (1995). After the test, the mortar mix was used for the measurement of setting time.
Samples were also made using examples of the first polymer and second polymers of the present invention separately and in combination. The first polymer is the one derived from Example 1 and comprises acrylic acid (as " X' " component having cement particle-attaching functionality) copolymerized to a polyethylene glycol group terminated with nonylphenyl pendant groups (as " Y' " hydrophobic group having non-covalently-associative functionality). The second polymer used comprised polyethylene oxide (as " Z' " particle-dispersing group) terminated with nonylphenyl pendant groups (as " Y" " hydrophobic group having non-covalently-associative functionality). The second polymer was commercially available from BASF under the tradename ICONOL. The ICONOL polymers are designated as NP-40, NP-50, NP-70, and NP-100 to identify the number of nonylphenyl repeating units (e.g., NP-40 signifies that the polymer has 40 repeating NP units). The mortar testing results are shown in Table 1.

Table 1


There was little enhanced flowability when the first polymer (particle-attaching) was used alone (See Mix # 2) or when the second polymer (having particle dispersing groups) was used alone (See Mix #3). However, when both the first polymer and second polymer components were used and allowed to form a non-covalent (hydrophobic) association in the slurry, the mixture remarkably showed high flowability (See Mix #4 - #7).
The foregoing examples are provided by way of illustration only and are not intended to limit the scope of the invention.