Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2000-07-31
2002-09-17
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S002000, C524S004000, C524S005000
Reexamination Certificate
active
06451881
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to an oligomeric dispersant. More particularly, the present invention is directed to an oligomeric dispersant for cementitious particles. Specifically, the present invention is directed to a reaction product of a moiety that adsorbs onto a particle to be dispersed, a moiety that provides the dispersing capability, and an optional moiety that is disposed between the other moieties to provide connections between the other moieties.
BACKGROUND OF THE INVENTION
A cementitious mixture refers to pastes, mortars, and concrete compositions comprising a hydraulic cement binder. Pastes are defmed as mixtures composed of a hydraulic cement binder, either alone or in combination with pozzolans such as fly ash, silica fume, or blast furnace slag, and water. Mortars are defined as pastes that additionally include fine aggregate. Concretes additionally include coarse aggregate. These compositions may additionally include other admixtures such as set retarders, set accelerators, defoaming agents, air-entraining or air detraining agents, corrosion inhibitors, water reducing agents, pigments, and any other admixture that does not adversely affect the advantageous results obtained by the present invention.
Dispersants are substances that improve the flow characteristics of the cement slurry by breaking up cement agglomerates and freeing the water, thus giving slurries of lower viscosity and allowing desirable flow conditions to be obtained at lower pump pressures.
V.S. Ramachandran, Concrete Admixtures Handbook: Properties, Science, and Technology
, Noyes Publications (Second Edition, 1995).
Dispersants have been used in the construction industry to disperse cementitious mixtures. Dispersants such as sulfonated melamine formaldehyde condensate (SMF), sulfonated naphthalene formaldehyde condensate (BNS), and lignosulfonates are commonly used as dispersants. However, these compounds require more than the desired amount of material to achieve a desired level of concrete workability or water reduction. In addition, these materials do not achieve full range (Type A to Type F) water reducing capability, as defined in ASTM C494. For example, lignosulfonates achieve only a low to mid range (5-12%) water reduction before severe set retardation occurs.
Dispersants are a necessary component in high strength and high durability concretes. Due to the requirement for the use of low water amounts in high performance concretes, sometimes high dispersant amounts are necessary to achieve workable concretes. High BNS levels can lead to undesirable retardation of set and may not provide the required workability retention over time.
It is desirable to provide a material that is several times more efficient as a cement or concrete dispersant than the traditional materials like lignosulfonates, BNS and SMF. Improving efficiency reduces the amount of material required to achieve a desired level of concrete workability or water reduction. With respect to the presently used dispersants, lignosulfonates, BNS and SMF, it is also desirable to improve slump retention while maintaining normal setting characteristics. Providing a dispersant with full range (Type A to F) water reducing capability is also a desirable characteristic.
One improvement in the prior art was to use polycarboxylate dispersants. Polycarboxylate dispersants are structured with a polymeric backbone, such as a carbon chain backbone, with pendant moieties. The pendant moieties provide the dispersing capabilities of the dispersant. Polycarboxylate dispersants are polymers with a carbon backbone with pendant side chains, wherein at least a portion of the side chains are attached to the backbone through a carboxyl group or an ether group. For example, polyacrylic acid has carboxylic groups attached to the backbone. Also, side chain moieties such as polyoxyalkylenes can be attached to the carboxylic groups to provide further dispersing capabilities. These dispersants operate by surrounding a particle to be dispersed, and then repulsion forces between each polymer chain keeps the particles apart and more fluid.
It is therefore an object of the invention to provide oligomeric dispersants for dispersing cementitious particles, wherein the dispersant adsorbs onto the particle to be dispersed.
SUMMARY OF THE INVENTION
The present invention provides a cementitious formulation comprising a cement and a dispersant comprising a reaction product of component A, component B, and component C; wherein each component A is independently a nonpolymeric, functional moiety that adsorbs onto a cementitious particle, and contains at least one residue derived from a first component selected from the group consisting of phosphates, phosphonates, phosphinates, hypophosphites, sulfates, sulfonates, sulfmates, alkyl trialkoxy silanes, alkyl triacyloxy silanes, alkyl triaryloxy silanes, borates, boronates, boroxines, phosphoramides, amines, amides, quaternary ammonium groups, carboxylic acids, carboxylic acid esters, alcohols, carbohydrates, phosphate esters of sugars, borate esters of sugars, sulfate esters of sugars, salts of any of the preceding moieties, and mixtures thereof; wherein component B is independently a nonpolymeric moiety that is disposed between the component A moiety and the component C moiety, and is derived from at least one of an alicyclic hydrocarbon and a heterocyclic hydrocarbon; and wherein component C is at least one moiety that is a linear or branched water soluble, nonionic polymer substantially non-adsorbing to cement particles, and is selected from the group consisting of poly(oxyalkylene glycol), poly(oxyalkylene amine), poly(oxyalkylene diamine), monoalkoxy poly(oxyalkylene amine), monoaryloxy poly(oxyalkylene amine), monoalkoxy poly(oxyalkylene glycol), monoaryloxy poly(oxyalkylene glycol), poly(vinyl pyrrolidones), poly(methyl vinyl ethers), poly(ethylene imines), poly(acrylamides), polyoxazoles, and mixtures thereof; wherein if the A moiety contains any phosphate, phosphonate, phosphinate, or hypophosphite residue the dispersant is further characterized by at least one of the following:
A) the dispersant has a structure selected from the group consisting of:
(C)
z
—B—A
x
—B—(C)
z
, (i)
(A
x
)
y
—B—C—B—(A
x
)
y
, (ii)
and mixtures thereof;
B) the dispersant has a structure of (A
x
)
y
—B—(C)
z
with the proviso that the B moiety and the A moiety are not bound to each other through an alkylidene amine linkage;
C) the C moiety is selected from the group consisting of poly(oxyalkylene amine), poly(oxyalkylene diamine), monoalkoxy poly(oxyalkylene amine), monoaryloxy poly(oxyalkylene amine), poly(vinyl pyrrolidones), poly(methyl vinyl ethers), poly(ethylene imines), poly(acrylamides), polyoxazoles, and mixtures thereof;
wherein x is an integer from 1 to 3 and represents the number of independent A moieties, y is an integer from 1 to 3 and represents the number of independent A moieties, and z is an integer from 1 to 3 and represents the number of independent C moieties.
The present invention also provides a cementitious formulation comprising a cement and a dispersant comprising a reaction product of component A, optionally component B, and component C; wherein each component A is independently a nonpolymeric, functional moiety that adsorbs onto a cementitious particle, and contains at least one residue derived from a first component selected from the group consisting of phosphates, phosphonates, phosphinates, hypophosphites, salts of any of the preceding moieties, and mixtures thereof; wherein component B is an optional moiety, where if present, each component B is independently a nonpolymeric moiety that is disposed between the component A moiety and the component C moiety, and is derived from a second component selected from the group consisting of linear saturated hydrocarbons, linear unsaturated hydrocarbons, saturated branched hydrocarbons, unsaturated branched hydrocarbons, alicyclic hydrocarbons, heterocyclic hydrocarbons, aryl, phosphoester, nitrogen containing c
Brower Lynn E.
Danko Frank
Lu Runhai
Packe-Wirth Ranier
Pickett John
MBT HoldingAG
Renner Kenner Greive Bobak Taylor & Weber
Szekely Peter
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