Titanium chelate dispersions

Details Titanium chelate dispersions Titanium chelate dispersions

2003-04-22

2004-05-18

Choi, Ling-Siu (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S219500, C526S316000

Reexamination Certificate

active

06737485

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a composition and a process therefor, in which the composition comprises a stable aqueous polymeric dispersion of titanium chelates.
BACKGROUND OF THE INVENTION
The polymers of chelated titanium orthoesters with water have a number of industrial uses. They are valuable in a variety of applications such as in pigments, catalysts, and surface modifiers. As used herein, the term “polymer” refers to both lower molecular weight oligomers and higher molecular weight polymers.
The polymers made by reacting titanium chelates with water are typically solid materials, which makes them difficult to prepare and use without specialized solids processing equipment. For many applications, a ready-made aqueous dispersion of such polymers would be preferable and easier to manufacture and handle, but generally the solid polymers quickly settle out of the water. This results in multiple layers and settled solids, which can be very difficult to resuspend and distribute uniformly throughout the water. A uniform distribution is necessary for uniform feeding to a continuous or multi-batch, process.
A number of patents such as, for example, JP 53036449, JP 530364450, JP 1999293171, JP 48034132, U.S. Pat. Nos. 3,694,475, 4,313,851, 4,609,746, 5,423,380, 5,478,802, 4,861,500, 4,749,040, and 4,470,915 disclose titanium chelate polymers and/or dispersions thereof. However, none discloses how to stabilize such a suspension in water, especially alcohol-free.
There is, therefore, a need for a more stable and/or easily redispersable aqueous dispersion of a titanium chelate polymer composition and a process therefor.
SUMMARY OF THE INVENTION
A composition comprises a titanium chelate polymer and a stabilizer in which the polymer comprises repeat units derived from a titanium chelate.
A process comprises (1) contacting a tetraalkyl titanate with a chelating agent to produce a product mixture comprising a titanium chelate and an alcohol; (2) contacting the product mixture with water under a condition effective to produce a dispersion of a titanium chelate polymer; (3) optionally reducing the alcohol content in the dispersion of titanium chelate polymer; and (4) contacting the dispersion with a stabilizing amount of a stabilizer to produce a stable dispersion of titanium chelate polymer.
DETAILED DESCRIPTION OF THE INVENTION
The term “stable dispersion” refers to a dispersion or suspension that remains substantially soluble or dispersible or suspended, or does not form a hardened or cemented settled solid layer, in a liquid, preferably aqueous, and more preferably water at about 25° C. for at least 1 day, preferably at least 3 days, and more preferably at least 5 days. The term further refers to a dispersion or suspension comprising suspended or dispersed solids that, upon settlement, are easily re-dispersed or resuspended. The dispersion preferably contains about 1 to about 75%, about 5 to about 75%, more preferably 10 to 50% by weight of the polymer. These dispersions preferably do hot settle readily and are easily redispersed. The number of repeat units can be from 2 to about 2000.
The polymer in the stable dispersion comprises one or more titanium chelate polymers. The term “titanium chelate polymer” refers to a polymer comprising repeat units derived from a titanium chelate having the formula of TiX
m
(OR)
n
, where X is a radical derived from a chelating agent, m represents an average of the integral numbers which individually range from 0 and to 2 but at least one m that cannot be 0, and n represents an average of the integral numbers which range from 2 to 4; and R is independently H, or an alkyl or aryl group which may be further substituted. One skilled in the art recognizes that this polymer generally comprises one or more repeat units selected from the formula selected from the group consisting of TiX
2
O, TiX
2
(OR)O, TiX(O)
2
, TiX(OR)O, TiX(OR)
2
O, Ti(O)
2
, Ti(OR)(O)
2
, and Ti(OR)
2
(O)
2
. The polymer may also contain unpolymerized monomers or intermediates such as, for example, Ti(X)
2
(OR)
2
, TiX(OR)
3
, Ti(OR)
4
, and units arising from other reactive species present during the polymerization.
A preferred chelating agent is an organic 1,3-dicarbonyl compound such as a diketone, a diester, a ketoester, and combinations of two or more thereof. A radical derived from any 1,3-diketone can be used. The preferred diketones include, but are not limited to, 2,4-pentanedione, 1,4-hexanedione, 1,3-pentanedione, 2,4-hexanedione, dipivaloyl methane, or combinations of two or more thereof.
Also, a radical derived from any 1,3-diester can be used. The preferred diesters include, but are not limited to, dimethyl malonate, diethyl malonate, or combinations thereof.
Similarly, a radical derived from any 1,3-ketoester can be used. The preferred ketoester include, but are not limited to, methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate, butyl acetoacetate, and combinations of two or more thereof.
The most preferred chelating agent is 2,4-pentanedione, ethyl acetoacetate, or combinations thereof. Especially preferred are those in which X is an acetylacetonato group and m averages about 2.
Examples of titanium chelate polymers include, but are not limited to, oxybis(2,4-pentanedionato)titanium homopolymer, oxybis(2,4-hexanedionato)titanium polymer, oxybis(2,2,6,6-tetramethyl-3,5-heptanedionato)titanium homopolymer, oxybis(diethylmalonato)titanium homopolymer, oxybis(ethyl 3-oxobutanoato-O1′,O3)titanium homopolymer, and combinations of two or more thereof.
Any compounds that, when combined with a titanium chelate polymer disclosed above, produce a stable dispersion of a titanium chelate polymer can be a stabilizer. Examples of stabilizers include hydroxy carboxylic acids, alkoxylated (for example, ethoxylated) quaternary ammonium salts, aminocarboxylic acid, alkanolamines, inorganic phosphate salts, or combinations of two or more thereof. Examples of hydroxy carboxylic acids include citric acid, lactic acid, glycolic acid, tartaric acid, malic acid, or combinations of two or more thereof. Examples of suitable alkoxylated quaternary ammonium salts include E-sperse 100®, available from Ethox Chemicals Co. (Greenville, S.C., USA). Examples of alkanolamines include ethanolamine, diethanolamine, triethanolamine, or combinations of two or more thereof. Examples of aminocarboxylic acid include tetrahydroxyisopropylethylenediamine, glycine, bis-hydroxyethyl glycine, hydroxyethyl glycine, or combinations of two or more thereof. Examples of inorganic phosphorus-containing salts include tetrapotassium pyrophosphate, potassium tripolyphosphate, sodium tripolyphosphate, potassium tetra phosphate, sodium pentapolyphosphate, sodium hexapolyphosphate, potassium pyrophosphate, potassium pyrophosphite, sodium pyrophosphate, sodium pyrophosphate decahydrate, sodium pyrophosphite, ethyl phosphonate, propyl phosphonate, hydroxymethyl phosphonate, di(polyoxyethylene)hydroxymethyl phosphonate, methylphosphonoacetate, ethyl methylphosphonoacetate, methyl ethylphosphonoacetate, ethyl ethylphosphonoacetate, propyl dimethylphosphonoacetate, methyl diethylphosphonoacetate, triethyl phosphonoacetate, or combinations of two or more thereof. Other stabilizers may also be used, as readily determined by, for example, simply mixing them with a titanium chelate polymer composition slurry. The preferred stabilizers are hydroxy carboxylic acids. The most preferred stabilizer is citric acid.
The above dispersions may optionally contain other components such as nonionic, cationic, or anionic surfactants, in the range of from about 0.001 to about 50 percent by weight of the dispersion.
A stabilizing amount of the stabilizer can be present in a composition. The term “stabilizing amount” means an amount that can produce a stable dispersion disclosed above and can range from about 0.001% to about 20%, preferably about 0.01% to about 10%, more preferably 0.01% to 5%, and most preferably 0.05% to 2%, by weight relative to the weight of aqueous dispersion.
The titanium chelate polymer ma

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