CONCENTRATED TITANIUM DIOXIDE SLURRY FOR USE FOR PAINTS AT THE POINT OF SALE

Abstract

The present invention relates to a titanium dioxide pigment composition for use in paint formulations, wherein the pigment composition comprises a plurality of titanium dioxide particles, and a dispersant package deposited on the surfaces of the titanium dioxide particles. The dispersant package includes water, at least one preservative, organic alkali salts, at least one thickener, at least one preservative, at least one defoamer, and at least one resin

Claims

1-4. (canceled)

5. A titanium dioxide slurry composition comprising: (a) a plurality of titanium dioxide particles present at a concentration ranging from about 60 wt. % to about 80 wt. %, by weight of the titanium dioxide slurry; and (b) a dispersant package comprising: (i) water; (ii) a preservative; (iii) a surfactant; (iv) a thickener; and (v) a defoamer.

6. The titanium dioxide slurry composition according to claim 5, wherein the titanium dioxide particles are present at a concentration from about 70 wt. % to about 80 wt. %, by weight of the titanium dioxide slurry.

7. The titanium dioxide slurry composition according to claim 5, wherein the titanium dioxide particles are coated with at least one of a silica, an alumina, and a zirconia.

8. The titanium dioxide slurry composition according to claim 5, wherein the water is present at a concentration ranting from about 9 wt. % to about 30 wt. %, by weight of the titanium dioxide slurry.

9. The titanium dioxide slurry composition according to claim 5, wherein at least one of: the defoamer comprises at least one of a silica, an ethylene oxide propylene oxide copolymer, an oil, a wax, Foamstar A-32, Foamstar A-34, Foamstar A-36, Foamstar A-38, Foamstar A-39, Foamaster 111, Foamaster 333, Foamaster SA-3, Tego Foamex 810, and the defoamer is present at a concentration ranging from about 0.1 wt. % to about 1 wt. %, by weight of the titanium dioxide slurry.

10. The titanium dioxide slurry composition according to claim 5, wherein the titanium dioxide particles are present at a concentration of at least about 70 wt. %, by weight of the titanium dioxide slurry.

11. The titanium dioxide slurry composition according to claim 5, wherein the dispersant package further comprises a dispersing agent comprising at least one of maleic acid copolymers, acrylic acid copolymers, methacrylic acid copolymers, tartaric acid, succinic acid, citric acid, itaconic acid.

12. The titanium dioxide slurry composition according to claim 5, wherein at least one of: the thickener comprises hydrophobic ethoxylated urethane resin (HEUR) thickeners, hydrophobically-modified, a colloidal clay, alkali-soluble or alkali-swellable emulsion (HASE), modified cellulosic thickeners, polysaccharide resin thickeners, attapulgite clay thickeners and mixtures thereof, and the thickener is present at a concentration ranging from about 0.1 wt. % to about 3 wt. %, by weight of the titanium dioxide slurry composition.

13. The titanium dioxide slurry composition according to claim 5, wherein at least one of: the preservative is present at a concentration ranging from about 0.5 wt. % to about 1.0 wt. %, by weight of the titanium dioxide slurry composition, and the preservative comprises at least one of 1,2-benzisothiazol-3(2H)-one, 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-2H-isothiazol-3-one.

14. The titanium dioxide slurry composition according to claim 5, wherein at least one of: the surfactant comprises a sodium salt of polycarboxylic acid, and the surfactant is present at a concentration ranging from about 1 wt. % to about 6 wt. %, by weight of the titanium dioxide slurry composition.

15. The titanium dioxide slurry composition according to claim 5, wherein the preservative comprises at least one of a biocide, a fungicide, and a mildewcide.

16. The titanium dioxide slurry composition according to claim 5, further comprising a propylene glycol at a concentration ranging from about 2 wt. % to about 8 wt. %, by weight of the titanium dioxide slurry.

17. The titanium dioxide slurry composition according to claim 5, further comprising a colloidal clay thickener at a concentration ranging from about 0.5 wt. % to about 1 wt. %, by weight of the titanium dioxide slurry.

18. The titanium dioxide slurry composition according to claim 5, an amine additive at a concentration ranging from about 0.5 wt. % to about 1.0 wt. %, by weight of the titanium dioxide slurry.

19. The titanium dioxide slurry composition according to claim 5, wherein at least one of: the titanium dioxide slurry composition has a viscosity ranging from about 1,000 cp to about 3,000 cp at a temperature of about 25, and titanium dioxide particles are produced by highly dispersing a selected grade of rutile titanium dioxide to a Hegman grind 7.5 N.S. in a water-based medium.

Description

DESCRIPTION OF THE INVENTION

[0022] In one aspect, a concentrated titanium dioxide slurry composition for use in paint formulations is provided. The composition comprises a plurality of titanium dioxide particles, and a dispersant package deposited on the surfaces of the titanium dioxide particles. The dispersant package includes water, at least one preservative, organic alkali salts, at least one thickener, at least one defoamer, and at least one resin.

[0023] The recitation of a numerical range using endpoints includes all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0024] The terms a, an, the, at least one, and one or more are used interchangeably. Thus, for example, a coating composition that contains an additive means that the coating composition includes one or more additives.

[0025] The term binder means a film-forming natural or synthetic polymer suitable for use in paints and other coating composition.

[0026] The term circulating when used with respect to a composition means that the composition is a fluid that may or may not contain dispersed solid particles and which is undergoing stirring, agitation, or other shear forces sufficient to mix components in the composition.

[0027] The term fluid when used in reference to a substance means that the substance is a liquid that may or may not contain dispersed solid particles and which has a loss modulus (G) greater than its storage modulus (G) and a loss tangent (tan ) greater than 1.

[0028] The term low VOC when used with respect to paints and other coating composition means that the coating composition contains less than about 5 wt. percent volatile organic compounds, preferably less than about 3 wt. % volatile organic compounds, more preferably less than about 1 wt. % volatile organic compounds and most preferably less than about 0.5 wt. % volatile organic compounds based upon the total coating composition weight.

[0029] The term pigment means an inorganic particulate material having light-reflective characteristics and a surface energy and particle size suitable for use in paints and other coating compositions.

[0030] The terms preferred and preferably refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude other embodiments from the scope of the invention.

[0031] The term solvent-borne when used with respect to paints or other coating compositions means that the major liquid vehicle or carrier for such coating composition is a nonaqueous solvent or mixture of nonaqueous solvents.

[0032] When used with respect to a component which may be found in a paint or other coating composition, the term substantially free of means containing less than about 1 weight percent of the component based on the coating composition weight.

[0033] The term water-borne when used with respect to paints and other coating compositions means that the major liquid vehicle or carrier for such coating composition is water.

[0034] The slurry according to the instant application comprises about 60 wt. % to about 80 wt. % titanium dioxide particles, wherein the titanium dioxide is produced by highly dispersing a selected grade of rutile titanium dioxide to a Hegman grind 7.5 N.S. in a water-based medium.

[0035] The disclosed titanium dioxide particles provide light scattering sites within a dried film of the disclosed coating compositions and impart hiding or opacity to the dried film. The titanium dioxide particles may have a variety of shapes and sizes but desirably will scatter photons having wavelengths in the spectral region from 300 nm to 750 nm and especially in the visible spectral region from 380 nm to 700 nm. Suitable shapes for the titanium dioxide particles include spherical shapes, such as a regular sphere, an oblate sphere, a prolate sphere, and an irregular sphere; cubic shapes such as a regular cube and a rhombus; plate-like shapes including a flat plate, a concave plate, and a convex plate; and irregular shapes. Particles having spherical shapes desirably have average diameters of about 10 nm to about 1,000 nm, e.g., about 100 nm to about 500 nm, about 200 nm to about 300 nm, or about 230 nm. Particles having non-spherical shapes desirably have a maximum diameter of up to about 1 micrometer, e.g., up to about 500 nm or up to about 300 nm. The titanium dioxide particles may include one or more coatings, e.g., of silica, alumina, zirconia or combinations thereof such as a silica coating and an alumina coating.

[0036] The disclosed compositions contain (and the disclosed methods may employ) water, which may be tap, deionized, distilled, reverse osmosis or recycled water. Preferably the pigment grind dispersion contains sufficient water to facilitate efficient pigment grind mixing (e.g., about 9 to about 30 weight percent water based on the weight of ingredients in the pigment grind dispersion).

[0037] The ingredient amounts in the disclosed pigment grind dispersions will to some extent depend upon the other ingredients present.

[0038] The disclosed method and composition can provide improved storage stability (for example, avoidance of undesirable changes in viscosity, such as rapid viscosity increases), reduced grit (viz., solid particle) formation, or both improved storage stability and reduced grit formation compared to pigment grind dispersions prepared using previously recommended methods. Improved storage stability, reduced grit formation or both improved storage stability and reduced grit formation are useful for a variety of reasons including facilitating inventory management, process control and process improvement in large-scale mixing of paints and other coating compositions.

[0039] The disclosed concentrated titanium dioxide slurry compositions may include optional ingredients that assist with or do not unduly interfere with pigment dispersion, such as extender particles, dispersing agents, defoamers, wetting agents and mixtures thereof.

[0040] Exemplary defoamers include silicones, ethylene oxide propylene oxide copolymers, oils and waxes such as FOAMSTAR A-32, FOAMSTAR A-34, FOAMSTAR A-36, FOAMSTAR A-38, FOAMSTAR A-39, FOAMASTER 111, FOAMASTER 333 and FOAMASTER SA-3 from Cognis, TEGO FOAMEX 810 from Evonik, mixtures thereof and other materials that will be familiar to persons having ordinary skill in the art, including products from other suppliers such as Air Products and Chemicals, Ashland, BASF, BYK-Gardner USA, Cytec, Rhone Poulenc and Troy Corporation. The defoamers may be present in an amount between about 0.5% and about 1%, based on the total weight of the composition.

[0041] Exemplary extender particles include calcium carbonate, calcium sulfate, barium sulfate, mica, clay, calcined clay, feldspar, nepheline, syenite, wollastonite, diatomaceous earth, alumina silicates, non-film forming polymer particles, aluminum oxide, silica, talc, mixtures thereof and other materials that will be familiar to persons having ordinary skill in the art.

[0042] Exemplary dispersing agents include anionic polyelectrolyte dispersants such as maleic acid copolymers, acrylic acid copolymers including methacrylic acid copolymers, and carboxylic acids such as tartaric acid, succinic acid, citric acid, itaconic acid, mixtures thereof and other materials that will be familiar to persons having ordinary skill in the art.

[0043] Other ingredients included in the concentrated titanium dioxide slurry compositions include cosolvents, wetting agents, surfactants, biocides, and/or pH regulators.

[0044] Exemplary thickeners and other theology modifiers include sedimentation inhibitors, hydrophobic ethoxylated urethane resin (HEUR) thickeners, hydrophobically-modified, alkali-soluble or alkali-swellable emulsion (HASE) thickeners), modified cellulosic thickeners, polysaccharide resin thickeners, attapulgite clay thickeners and mixtures thereof. Exemplary commercially-available rheology modifiers include NATROSOL 250 and the AQUAFLOW series from Ashland, ATTAGEL 50 from BASF Corp., the CELLOSIZE series and UCAR POLYPHOBE T-900 and T-901 from Dow Chemical Co., BENTONE AD and BENTONE EW from Elementis Specialties, LATTICE NTC-61 from FMC Biopolymer and ACRYSOL RM-6, ACRYSOL RM-8, ACRYSOL RM-12W and ACRYSOL RM-2020NPR all from Rohm & Haas. When a rheology modifier is present, the coating compositions preferably contain about 0.1 to about 3 or about 0.5 to about 3 weight percent rheology modifier based on the final coating composition weight.

[0045] The compositions may also contain a variety of other adjuvants that will be familiar to persons having ordinary skill in the art. Representative adjuvants are described in Koleske et al., Paint and Coatings Industry, April 2003, pages 12-86. Exemplary adjuvants and commercial examples of the same include biocides, fungicides, mildewcides and preservatives (e.g., BUSAN 1292 from Buckman Laboratories, Inc., NOPCOCIDE N-40D from Cognis, KATHON LX from Rohm & Haas, and POLYPHASE 663, POLYPHASE 678 and POLYPHASE PW-40 from Troy Corporation, 1,2-benzisothiazol-3(2H)-one, 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-2H-isothiazol-3-one); curing indicators; heat stabilizers; leveling agents; light stabilizers (e.g., hindered amine light stabilizers such as TINUVIN 123-DW and TINUVIN 292 HP from Ciba Specialty Chemicals); optical brighteners; ultraviolet light absorbers (e.g., TINUVIN 234 and TINUVIN 1130 from Ciba Specialty Chemicals); wetting agents (e.g., BYK 346 and BYK 348 from Altana, PENTEX 99 from Rhodia and TROYSOL LAC from Troy corporation); waxes (e.g., AQUACER 593 from Altana, HYDROCER 303 from Shamrock Technologies, Inc. and MICHEM Emulsion 32535 from Michelman, Inc.); and the like. The types and amounts of these and other adjuvants typically will be empirically selected.

[0046] The surface-treated titanium dioxide pigment according to the present application is an active coloring agent that is suspended in aqueous medium with the support of a rheological matrix provided by a balanced combination of modified cellulosic thickener and attapulgite clay. The mixture is stabilized by the addition of a specially selected polycarboxylic acid sodium salt as a surfactant and an amine additive as a pH regulator. The functionality of the mixture is enhanced with a carefully balanced combination of glycol cosolvent and polysaccharide resin acting as humectants and flow agents.

[0047] More particularly, in a particularly preferred embodiment, the concentrated titanium dioxide slurry composition comprises between about 60 wt. % and about 80 wt. % rutile titanium dioxide pigment, about 9.0 to about 30 wt. % water, about 0.5 to about 1.0 wt. % wet state biocide preservative, about 0.5 wt. % to about 1.0 wt. % cellulosic thickener, about 0.5 wt. % to about 1.0 wt. % attapulgite clay thickener, about 2.0 wt. % to about 8.0 wt. % propylene glycol, about 1.0 wt. % to about 6.0 wt. % sodium salt of polycarboxylic acid, about 0.5 wt. % to about 1.0 wt. % silica base defoamer, about 0.5 wt. % to about 1.0 wt. % amine additive, about 1.0 wt. % to about 8.0 wt. % polysaccharide resin derivative.

[0048] The viscosity of the concentrated titanium dioxide slurry compositions according to the instant application may be between about 1000 cp and about 3000 cp at 25 C.

[0049] The concentrated titanium dioxide slurry compositions may be packaged in any convenient packaging suitable for storing a desired quantity of the coating composition without premature gelation, undue separation, or other undesirable degradation during storage. Exemplary packaging containers include cans, pails, bottles, drums, totes, and tanks. The disclosed compositions may be factory-applied to substrates such as building components at a manufacturing site or may be supplied to end users and applied onsite to finished articles, e.g., as paints for use on decks, siding, roofing, or other surfaces.

[0050] Having thus described preferred embodiments of the present invention, those of skill in the art will readily appreciate that the teachings found herein may be applied to yet other embodiments within the scope of the claims hereto attached. The complete disclosure of all patents, patent documents, and publications are incorporated herein by reference as if individually incorporated.