Processed titanium dioxide dye

Abstract

A process for producing treated titanium dioxide dyes is provided. The process includes providing a plurality of inorganic dye particles and depositing an organic treatment agent on the surface of the dye particles to form at least one coating of the organic treatment agent. The organic treatment agent includes a first component consisting of at least one polyhydric alcohol and a second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof. Treated titanium dioxide dyes are also provided.

Description

Background Art

[0001] Titanium dioxide is an effective pigment and white opacifying agent and is used in a variety of applications. For example, titanium dioxide pigments are commonly added to polymers, coatings (such as aqueous paints and ink formulations), paper, and other types of products. Due to its high refractive index, strong opacifying ability, and other factors, titanium dioxide (TiO2) has become one of the most commonly used white pigments worldwide.

[0002] Purified titanium dioxide (TiO2) is produced from raw ores (such as ilmenite and rutile) by either the sulfuric acid process or the chloride process. Each process can produce the pigment in its rutile crystal form. The sulfuric acid process can also produce the pigment in the anatase crystal form, which is softer and may be particularly useful for certain applications. The titanium dioxide pigment produced is generally in powder form.

[0003] Whether produced by the sulfuric acid process or the chloride process, the titanium dioxide particles produced are generally further processed to form a finished pigment. The steps utilized in the finishing process depend on the specific pigment characteristics and the desired characteristics for the intended application.

[0004] For example, the titanium dioxide produced is typically coated with one or more inorganic materials that modify or enhance the characteristics and properties of the pigment for a particular application. Examples of inorganic materials utilized include silica, zirconia, and alumina. For example, such materials can function to improve the opacity, light stability, and / or durability of the pigment. Inorganic materials are generally coated onto titanium dioxide particles by forming an aqueous slurry of the particles and depositing the inorganic material on the surface of the particles in the slurry.

[0005] The primary property to which titanium dioxide dyes contribute to paints, paper, plastics, and other products is their hiding power. The hiding power of titanium dioxide dyes is based on their ability to scatter light in the base product to which they are added (e.g., paint formulations). The ability of the dye to scatter light in the base product to which it is added (the light scattering efficiency of the dye) depends on a variety of factors, including the particle size distribution of the dye and the difference in refractive index between the dye particles and their surroundings. The surface treatment, particle size, and particle size distribution of titanium dioxide dyes also affect the surface gloss and grit of the dried coating film.

[0006] Following treatment of titanium dioxide pigment with one or more inorganic materials in the slurry stage, the treated titanium dioxide pigment is typically then filtered, washed, and dried. The dried pigment is then milled in a fluid energy mill, such as a steam micronizer, to break up pigment aggregates. Typically, at least one organic chemical is added to the dried aggregated titanium dioxide pigment in the fluid energy mill to act as a grinding aid and facilitate the milling process. Organic chemicals commonly coated on the surface of titanium dioxide particles can also improve the performance of the pigment in the final use application.

[0007] Trimethylolpropane (TMP) is an organic compound widely used for surface treatment of titanium dioxide dye particles for a variety of purposes. For example, TMP is used as a grinding aid in milling processes and is commonly used to improve the flow and dispersion properties of dyes. Unfortunately, the TMP Consortium, which is related to the European Union's Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) regulations, has voluntarily classified TMP as potentially reproductively toxic. As a result, there is a need for other organic treatment agents that can replace TMP. [Overview of the Initiative]

[0008] A process for producing a treated titanium dioxide dye, comprising the steps of providing a plurality of titanium dioxide dye particles and depositing an organic treatment agent onto the surface of the dye particles to form a coating of the organic treatment agent on the surface. The organic treatment agent comprises a first component consisting of at least one polyhydric alcohol and a second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof.

[0009] A treated titanium dioxide dye comprising a plurality of titanium dioxide dye particles and an organic treatment agent deposited on the surface of the titanium dioxide dye particles to form a coating of the organic treatment agent on the surface. The organic treatment agent comprises a first component consisting of at least one polyhydric alcohol and a second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof. [Modes for carrying out the invention]

[0010] This disclosure can be readily understood by referring to this detailed description and the examples contained herein. Many specific details are given to provide a full understanding of the various aspects of this disclosure. However, this detailed description is not intended to be considered limiting of the claims. The subject matter disclosed herein is highly modifiable, adapted, combined, and equivalent in form and function, as will be apparent to those skilled in the art, in the interest of this disclosure.

[0011] Whenever a numerical range is disclosed herein, that range includes all members of the range that span between any two numbers enumerated within the range, independently and separately. Furthermore, the lowest and highest numbers of any range are understood to fall within the indicated range.

[0012] In one embodiment, a process for producing a treated titanium dioxide dye is disclosed herein. In another embodiment, a treated titanium dioxide dye is disclosed herein.

[0013] The process disclosed herein includes providing a plurality of titanium dioxide particles and depositing an organic treatment agent on the surface of the pigment particles to form a coating of the organic treatment agent on the surface. The organic treatment agent includes a first component consisting of at least one polyhydric alcohol and a second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof.

[0014] As used herein and in the accompanying claims, titanium dioxide dye means particulate titanium dioxide, i.e., titanium dioxide dye in the form of a plurality of titanium dioxide dye particles. For example, titanium dioxide may be in the form of a dry powder or dry granules. As used herein and in the accompanying claims, “deposited,” “formed,” and “precipitated” on the surface of titanium dioxide or dye particles (or another component, e.g., another coating) means, unless otherwise specified, that they are deposited, formed, or precipitated (as they may be) directly or indirectly on the surface of titanium dioxide or dye particles (or other components). For example, unless otherwise specified, “deposited on the surface of titanium dioxide particles” means formed directly on the titanium dioxide particles or on one or more organic and / or inorganic coatings formed directly or indirectly on the titanium dioxide particles.

[0015] For example, titanium dioxide particles may be provided by producing titanium dioxide dye as part of a process disclosed herein. Alternatively, titanium dioxide particles may be provided from a source of titanium dioxide dye that has already been produced. For example, one or more bulk containers (e.g., bags) of an existing titanium dioxide dye may be used as a source of titanium dioxide dye.

[0016] The method by which the titanium dioxide particles are produced, whether as part of a process disclosed herein or not, is not critical. For example, the titanium dioxide particles may be titanium dioxide particles produced by a sulfuric acid process. For example, the titanium dioxide particles may be titanium dioxide particles produced by a chlorine process. The particles may have a rutile crystal structure, anatase crystal structure, or a combination thereof. For example, the titanium dioxide particles may have a rutile crystal structure. For example, the titanium dioxide particles may have anatase crystal structure.

[0017] In the sulfuric acid process for producing titanium dioxide, titanium slag ore, usually ilmenite, is dissolved in sulfuric acid to form titanyl sulfate. Titanyl sulfate is then hydrolyzed to form hydrated titanium dioxide. The hydrated titanium dioxide is heated in a calcination furnace to grow titanium dioxide crystals to the required size.

[0018] In a chlorination process for producing titanium dioxide, dried titanium dioxide ore is supplied to a chlorinator along with coke and chlorine to produce gaseous titanium halide (e.g., titanium tetrachloride). The produced titanium halide is purified and oxidized at high temperature in a specially designed reactor to produce purified titanium dioxide particles with a desired particle size distribution. Aluminum chloride is typically added to the titanium halide in an oxidation reactor to incorporate alumina into the crystal lattice of the titanium dioxide particles, thereby promoting rutile formation and controlling particle size. The titanium dioxide and gaseous reaction products are then cooled to recover the titanium dioxide particles.

[0019] Titanium dioxide particles may contain alumina as part of their lattice structure. For example, aluminum chloride may be added to the reactants as a rutile-adding agent during the vapor phase oxidation step of the chlorine process. When present during the oxidation reaction, aluminum chloride adds alumina into the lattice structure of the pigment.

[0020] For example, the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from about 0.1% to about 1% by weight, based on the weight of the titanium dioxide particles. For example, the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from about 0.2% to about 0.9% by weight, based on the weight of the titanium dioxide particles. For example, the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from about 0.4% to about 0.7% by weight, based on the weight of the titanium dioxide particles. As used herein and in accompanying claims, unless otherwise specified, "based on the weight of the titanium dioxide particles" means based on the weight of the dry raw titanium dioxide particles.

[0021] For example, the ratio of the first component to the second component in the organic treatment agent may be in the range of approximately 1:1 to approximately 20:1. For example, the ratio of the first component to the second component in the organic treatment agent may be in the range of approximately 2:1 to approximately 10:1. For example, the ratio of the first component to the second component in the organic treatment agent may be in the range of approximately 3:1 to approximately 7:1. For example, the ratio of the first component to the second component in the organic treatment agent may be approximately 5:1.

[0022] For example, the first component polyhydric alcohol (multiple) of the organic treatment agent may be selected from the group consisting of glycerol, polyglycerol, mannitol, xylitol, erythritol, and combinations thereof. For example, the first component polyhydric alcohol (multiple) of the organic treatment agent may be selected from the group consisting of glycerol, mannitol, xylitol, erythritol, and combinations thereof. For example, the first component polyhydric alcohol (multiple) of the organic treatment agent may be selected from the group consisting of glycerol, xylitol, erythritol, and combinations thereof. For example, the first component polyhydric alcohol (multiple) of the organic treatment agent may be selected from the group consisting of glycerol, xylitol, and combinations thereof. For example, the first component polyhydric alcohol (multiple) of the organic treatment agent may be glycerol.

[0023] For example, the first component of the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from about 0.1% to about 0.99% by weight, based on the weight of the titanium dioxide particles. For example, the first component of the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from about 0.2% to about 0.9% by weight, based on the weight of the titanium dioxide particles. For example, the first component of the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from about 0.4% to about 0.7% by weight, based on the weight of the titanium dioxide particles.

[0024] For example, the second component of the organic treatment agent may be at least one carboxylic acid and / or a salt thereof. The carboxylic acid(s) and / or salt(s) may be selected from the group consisting of monocarboxylic acids, dicarboxylic acids, hydroxylcarboxylic acids, salts of monocarboxylic acids, salts of dicarboxylic acids, salts of hydroxylcarboxylic acids, and combinations thereof. For example, the carboxylic acid(s) and / or salt(s) may be selected from the group consisting of benzoic acid, adipic acid, propionic acid, citric acid, lactic acid, tartaric acid, salts of benzoic acid, salts of adipic acid, salts of propionic acid, salts of citric acid, salts of lactic acid, salts of tartaric acid, and combinations thereof. For example, the carboxylic acid(s) and / or salt(s) may be selected from the group consisting of benzoic acid, citric acid, lactic acid, salts of benzoic acid, salts of citric acid, salts of lactic acid, and combinations thereof. For example, the carboxylic acid(s) and / or salt(s) therefor may be selected from the group consisting of benzoic acid, lactic acid, salts of benzoic acid, salts of lactic acid, and combinations thereof.

[0025] For example, the second component of the organic treatment agent may be at least one alkanolamine. For example, the alkanolamine(s) may be selected from the group consisting of hydroxylamine, triisopropanolamine (TIPA), triethanolamine (TEOA), tris(hydroxymethyl)aminomethane, and combinations thereof. For example, the alkanolamine(s) may be selected from the group consisting of triisopropanolamine (TIPA), triethanolamine (TEOA), and combinations thereof. For example, the alkanolamine(s) may be triisopropanolamine (TIPA).

[0026] For example, the second component of the organic treatment agent may be at least one carboxylate and / or salt thereof, accompanied by one or more alkanolamines. For example, the carboxylic acid(s) and / or salt(s) thereof may be selected from the group described above. For example, the alkanolamine(s) may be selected from the group described above.

[0027] For example, the second component of the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from approximately 0.01% to approximately 0.9% by weight, based on the weight of the titanium dioxide particles. For example, the second component of the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from approximately 0.03% to approximately 0.5% by weight, based on the weight of the titanium dioxide particles. For example, the second component of the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from approximately 0.05% to approximately 0.4% by weight, based on the weight of the titanium dioxide particles.

[0028] For example, when the second component of the organic treating agent is one or more carboxylic acids or their salts, it may be deposited on the surface of the pigment particles in an amount ranging from about 0.1% to about 0.6% by weight based on the weight of the titanium dioxide particles. For example, when the second component of the organic treating agent is one or more carboxylic acids or their salts, it may be deposited on the surface of the pigment particles in an amount ranging from about 0.15% to about 0.5% by weight based on the weight of the titanium dioxide particles. For example, when the second component of the organic treating agent is one or more carboxylic acids or their salts, it may be deposited on the surface of the pigment particles in an amount ranging from about 0.2% to about 0.4% by weight based on the weight of the titanium dioxide particles.

[0029] For example, when the second component of the organic treating agent is one or more alkanolamines, it may be deposited on the surface of the pigment particles in an amount ranging from about 0.01% to about 0.2% by weight based on the weight of the titanium dioxide particles. For example, when the second component of the organic treating agent is one or more alkanolamines, it may be deposited on the surface of the pigment particles in an amount ranging from about 0.02% to about 0.16% by weight based on the weight of the titanium dioxide particles. For example, when the second component of the organic treating agent is one or more alkanolamines, it may be deposited on the surface of the pigment particles in an amount ranging from about 0.04% to about 0.12% by weight based on the weight of the titanium dioxide particles.

[0030] The organic treating agent may be deposited on the surface of the titanium dioxide pigment particles by any technique known in the art for surface - treating pigments. For example, the organic treating agent may be deposited on the surface of the pigment particles in a fluid energy mill. When the titanium dioxide pigment particles are of the dry type, the organic treating agent may be mixed with the pigment particles or sprayed onto the pigment particles. The organic treating agent may also be added to a slurry containing the pigment particles and dried with the slurry.

[0031] For example, in one embodiment, the process includes forming a slurry of pigment particles and filtering the pigment particles to form a filter cake containing the pigment particles, before depositing an organic treatment agent onto the surface of the titanium dioxide pigment particles. The filter cake and the organic treatment agent are then mixed so that the organic treatment agent is deposited onto the surface of the pigment particles forming the filter cake, forming a coating of the organic treatment agent thereon.

[0032] For example, the filtration step washes and recovers the pigment particles. The recovered pigment particles may then be dried as part of the pigment finishing process. The organic treatment agent may be mixed with the filtered cake before or after the filtered cake is dried.

[0033] For example, the process may further include milling the treated pigment particles after the organic treatment agent has been mixed with the filtered cake and deposited on the surface of the pigment particles, and after the filtered cake has been dried. For example, the pigment particles may be milled in a fluid energy mill. For example, the pigment particles may be milled by steam milling technology. For example, the organic treatment agent acts as a grinding aid to facilitate the milling process.

[0034] For example, in one embodiment, the process further includes depositing an inorganic treatment agent on the surface of the dye particles to form a coating of the inorganic treatment agent before depositing an organic treatment agent on the surface of the dye particles. For example, the organic treatment agent may be deposited on top of the coating of the inorganic treatment agent to form a coating thereon.

[0035] For example, the first inorganic treatment agent may be deposited on the surface of the pigment particles to form a coating of the first inorganic treatment agent thereon, or the second inorganic treatment agent may be deposited on the coating of the first inorganic treatment agent to form a coating of the second organic treatment agent thereon. Then, the third inorganic treatment agent may be deposited on the coating of the second inorganic treatment agent to form a coating of the third inorganic treatment agent thereon, and so on.

[0036] For example, if more than one inorganic treatment agent is deposited on the surface of the pigment particles to form more than one inorganic treatment agent coating thereon, the organic treatment agent will be deposited on all of the inorganic treatment agent coatings. For example, if the first and second inorganic treatment agents are deposited directly or indirectly on the surface of the pigment particles, then the organic treatment agent will be deposited on the coating of the second inorganic treatment agent. For example, when an organic treatment agent is deposited on a coating (or more) of inorganic treatment agents (and any other organic material deposited on the surface of titanium dioxide particles), the compatibility between the polymer resin matrix and the pigment may be enhanced, for example, when the treated titanium dioxide pigment is added to a polyolefin.

[0037] For example, inorganic treatment agents may be deposited on the surface of titanium dioxide particles by forming an aqueous slurry of titanium dioxide particles, precipitating the inorganic treatment agents on the surface of the titanium dioxide particles in the slurry, and forming one or more coatings of the inorganic treatment agents thereon. Techniques for precipitating one or more inorganic or organic treatment agents directly or indirectly on the surface of titanium dioxide particles, such as titanium dioxide dye particles in a slurry containing titanium dioxide particles, are known in the art, by sequentially adding each treatment agent to the slurry and adjusting the pH of the slurry as necessary to precipitate the treatment agents on the surface of the titanium dioxide particles. Inorganic and organic treatment agents may be deposited in situ on titanium dioxide particles in an aqueous slurry.

[0038] For example, to deposit a metal oxide inorganic treatment agent on the surface of multiple titanium dioxide particles and form a coating thereon, the metal oxide inorganic treatment agent may be gradually added to the aqueous slurry as an aqueous metal oxide salt solution. The pH and temperature of the slurry may be adjusted and maintained to a level at which precipitation of a specific metal oxide inorganic treatment agent occurs. To adjust the pH of the slurry, strong inorganic acids, such as hydrochloric acid, nitric acid, sulfuric acid, and their salts may be used. For example, each distinct inorganic treatment agent precipitated on the surface of the titanium dioxide particles in the slurry forms a distinct coating directly or indirectly on the surface of the titanium dioxide particles.

[0039] For example, the inorganic treatment agent(s) may be selected from the group consisting of metal oxide materials, metal hydroxide materials, and combinations thereof. For example, the inorganic treatment agent(s) may be selected from the group consisting of silica materials, alumina materials, aluminum phosphate materials, zirconia materials, and titania materials. For example, the inorganic treatment agent(s) may be selected from the group consisting of silica materials, alumina materials, and zirconia materials. If more than one inorganic treatment agent(s) are used, the inorganic treatment agents may be the same or different.

[0040] Inorganic treatment agents may be used to impart one or more properties and / or characteristics to titanium dioxide particles, or to enhance such properties and / or characteristics, making the particles more suitable for end-use applications, i.e., for use in base compositions (e.g., polymer compositions) to which titanium dioxide is intended to be added and products manufactured therefrom (e.g., plastic articles). For example, silica and / or alumina treatment agents may be used to assist in improving the wetting and dispersion properties of titanium dioxide dyes, as well as the opacity, photostability, and durability of the dyes.

[0041] For example, the inorganic treatment agent(s) may be deposited on the surface of the titanium dioxide particles in an amount ranging from approximately 0.2% to approximately 15% by weight, based on the total weight of the raw titanium dioxide particles and all inorganic and organic materials deposited thereon. For example, the inorganic treatment agent(s) may be deposited on the surface of the titanium dioxide particles in an amount ranging from approximately 0.5% to approximately 10% by weight, based on the total weight of the raw titanium dioxide particles and all inorganic and organic materials deposited thereon.

[0042] For example, in one embodiment, the above-described organic treatment agent is a second organic treatment agent, and the process further includes depositing a first organic treatment agent on the surface of pigment particles to form a coating of the first organic treatment agent on that surface.

[0043] For example, the first organic treatment agent, like a second organic treatment agent, may be deposited on the surface of pigment particles by any technique relating to surface treatment pigments known in the art to form a coating of the first organic treatment agent thereon. For example, the first organic treatment agent may be deposited on the surface of pigment particles in a fluid energy mill. The first organic treatment agent may be mixed with the pigment particles or sprayed onto the pigment particles if the pigment particles are of the dry type. The first organic treatment agent may also be added to a slurry containing pigment particles and dried together with the slurry.

[0044] As a further example, the first organic treatment agent, like the second organic treatment agent, may be mixed with a filtered cake containing the pigment particles as described above (either before or after the filtered cake is dried). The treated pigment particles (containing the first organic treatment agent, the second organic treatment agent, and optionally one or more inorganic treatment agents) may then be milled as described above.

[0045] For example, the first organic treatment agent may be deposited on the surface of the pigment particles before the second organic treatment agent is deposited on the surface of the pigment particles. For example, in one embodiment, after a filtration cake containing pigment particles is formed as described above, the first organic treatment agent is deposited on the surface of the pigment particles forming the filtration cake to form a coating of the first organic treatment agent thereon. Next, the second organic treatment agent is deposited on the surface of the pigment particles forming the filtration cake to form a coating of the second organic treatment agent thereon. For example, the filtration cake may be dried after the first organic treatment agent has been deposited on the surface of the pigment particles forming the filtration cake, and before the second organic treatment agent is deposited on the surface of the pigment particles forming the filtration cake. Once both the first and second treatment agents have been deposited on the pigment particles forming the filtration cake, the treated pigment particles (which contain the first organic treatment agent, the second organic treatment agent, and optionally one or more inorganic treatment agents) may then be milled as described above.

[0046] For example, the first organic treatment agent may be selected from the group consisting of alkylphosphinic acid, alkylphosphinic acid derivatives, phosphonic acid, phosphonic acid derivatives, siloxane, and combinations thereof.

[0047] Examples of usable alkylphosphinic acids and alkylphosphinic acid derivatives include bis(2,4,4-trimethylpentyl)phosphinic acid, bis(2-ethylhexylphosphinic acid), oleylphosphinic acid, n-octadecylphosphinic acid, phosphinic acid esters, and combinations thereof. An example of a usable phosphinic acid ester is bis(2-ethylhexyl)phosphinic acid 2-ethylhexyl ester.

[0048] Examples of usable phosphonic acids and derivatives of phosphonic acids include n-octylphosphonic acid, decylphosphonic acid, dodecylphosphonic acid, octylphosphonic acid, phosphonic acid esters, phosphonic acid salts, and combinations thereof. Examples of usable phosphonic acid esters include alkylphosphonic acid esters. An example of a usable phosphonic acid salt is the monoethyl potassium salt.

[0049] Examples of usable siloxanes include polydimethylsiloxane, copolymers of polydimethylsiloxane and polymethylhydrogensiloxane, n-octyltriethoxysilane, silicone alkyl polyethers, silicone polyether carboxylates, and combinations thereof.

[0050] For example, the first organic treatment agent may be selected from the group consisting of alkylphosphinic acids, phosphonic acids, siloxanes, and combinations thereof. For example, the first organic treatment agent may consist of one or more alkylphosphinic acids. For example, the first organic treatment agent may be bis(2,4,4-trimethylpentyl)phosphinic acid.

[0051] For example, the first organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from about 0.05% to about 1.0% by weight, based on the weight of the titanium dioxide particles. For example, the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from about 0.1% to about 0.8% by weight, based on the weight of the titanium dioxide particles. For example, the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from about 0.2% to about 0.6% by weight, based on the weight of the titanium dioxide particles.

[0052] For example, in one embodiment, the process disclosed herein includes the following steps: (a) the step of providing a plurality of titanium dioxide particles; (b) After step (a), a step of forming an aqueous slurry of titanium dioxide particles; (c) After step (b), the particle size of titanium dioxide particles in the aqueous slurry is reduced to a desired particle size distribution; (d) After step (c), the step of depositing inorganic treatment agents on the surface of titanium dioxide particles in an aqueous slurry (or depositing one or more inorganic treatment agents sequentially) to form a coating of inorganic treatment agents thereon (or forming separate coatings for each inorganic treatment agent thereon); (e) After step (d), the surface-treated titanium dioxide particles are filtered to form a filtered cake containing the surface-treated titanium dioxide particles; (f) After step (e), the organic treatment agent is mixed with the filtration cake to deposit the organic treatment agent onto the inorganic treatment agent(s) coating(s); (g) After step (g), the step of drying the filtered cake; (h) After step (g), the particle size of the treated titanium dioxide particles is reduced to a desired particle size distribution;

[0053] (i) A step of packaging the treated titanium dioxide after step (i). As discussed above, titanium dioxide particles may be provided in step (a) by producing a titanium dioxide dye as part of the process disclosed herein. Alternatively, the titanium dioxide particles may be provided in step (a) from a titanium dioxide source that has already been produced.

[0054] A titanium dioxide particle slurry may be formed in step (b) by mixing titanium dioxide particles in an aqueous medium. If necessary or desirable, a dispersant, such as a polyphosphate, may be added to the aqueous slurry to promote the distribution of titanium dioxide particles therein. For example, titanium dioxide particles may be added to the aqueous slurry in an amount ranging from about 5% to about 65% by weight, based on the total weight of the slurry. As a further example, titanium dioxide particles may be added to the slurry in an amount ranging from about 15% to about 45% by weight, based on the total weight of the slurry. For example, titanium dioxide particles may be added to the aqueous slurry in an amount ranging from about 25% to about 40% by weight, based on the total weight of the slurry.

[0055] In step (c), the particle size of the titanium dioxide particles may be reduced to a desired size distribution by wet milling the dye particles in the aqueous slurry. For example, the dye particles in the aqueous slurry may be wet milled so that at least about 50% of the titanium dioxide particles in the slurry have a particle size of less than 0.5 microns. The wet milling step may be carried out using a variety of wet milling techniques known in the art, including milling, bead milling, jet milling, and sand milling.

[0056] As discussed above, inorganic treatment agents may be deposited on the surface of titanium dioxide particles according to step (d) by precipitation of inorganic treatment agents on the surface of titanium dioxide particles, thereby forming one or more coatings of inorganic treatment agents on the surface in the slurry.

[0057] The treated titanium dioxide particles may be filtered to form a filtration cake containing the surface-treated titanium dioxide particles according to step (e) by a method known to those skilled in the art. For example, the treated titanium dioxide particles may be recovered by filtration using conventional vacuum and / or pressure filtration systems to form a filtration cake of particles, which may then be washed. Wet deposition of inorganic treatment agents (e.g., onto wet-milled titanium dioxide particles) on the titanium dioxide particles helps to allow the dye to be recovered and washed using conventional vacuum and / or pressure filtration systems.

[0058] In accordance with step (f), the organic treatment agent may be mixed with the filtration cake to deposit the organic treatment agent onto the inorganic treatment agent coating(s) by any technique known to those skilled in the art. In one embodiment, the organic treatment agent is a second organic treatment agent as described above, and step (f) includes mixing both the first and second organic treatment agents with the filtration cake to deposit the organic treatment agent onto the inorganic treatment agent coating(s) as described above.

[0059] The filtration cake may be dried according to step (g) by vacuum drying, spin flash drying, spray drying, or other techniques known to those skilled in the art to produce dried titanium dioxide powder. In one embodiment, the filtration cake is dried by spray drying the particles according to step (g).

[0060] In step (h), the particle size of the treated titanium dioxide particles forming the dry filtration cake may be reduced to a desired particle size distribution, for example, by dry milling the pigment particles. For example, the pigment particles may be dry milled using a fluid energy mill. Alternatively, the dry pigment particles may be reduced to a desired particle size distribution by steam milling (e.g., steam milling) technique.

[0061] The treated titanium dioxide may then be packaged using any packaging technique known in the art. For example, the dried and milled treated inorganic oxide dye may be placed in a bag and transported in that bag.

[0062] In one embodiment, the inorganic treatment agent is not deposited on the surface of the titanium dioxide particles, i.e., step (d) is not included. In this embodiment, the first and second organic treatment agents are deposited directly or indirectly on the surface of the dye particles.

[0063] The treated titanium dioxide dyes provided herein comprise a plurality of titanium dioxide particles and an organic treatment agent deposited on the surface of the titanium dioxide particles to form a coating of the organic treatment agent on that surface. The organic treatment agent comprises a first component consisting of at least one polyhydric alcohol and a second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof.

[0064] For example, the titanium dioxide particles may be titanium dioxide particles produced by a sulfuric acid process. For example, the titanium dioxide particles may be titanium dioxide particles produced by a chlorine process. The titanium dioxide particles may have a rutile crystal structure, anatase crystal structure, or a combination thereof. For example, the titanium dioxide particles may have a rutile crystal structure. For example, the titanium dioxide particles may have anatase crystal structure.

[0065] For example, the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from approximately 0.1% to approximately 1% by weight, based on the weight of the titanium dioxide particles. For example, the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from approximately 0.2% to approximately 0.9% by weight, based on the weight of the titanium dioxide particles. For example, the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from approximately 0.4% to approximately 0.7% by weight, based on the weight of the titanium dioxide particles.

[0066] For example, the ratio of the first component to the second component in the organic treatment agent may be in the range of approximately 1:1 to approximately 20:1. For example, the ratio of the first component to the second component in the organic treatment agent may be in the range of approximately 2:1 to approximately 10:1. For example, the ratio of the first component to the second component in the organic treatment agent may be in the range of approximately 3:1 to approximately 7:1. For example, the ratio of the first component to the second component in the organic treatment agent may be approximately 5:1.

[0067] For example, the first component polyhydric alcohol (or more) of the organic treatment agent may be selected from the group consisting of glycerol, polyglycerol, mannitol, xylitol, erythritol, and combinations thereof. For example, the first component polyhydric alcohol (or more) of the organic treatment agent may be selected from the group consisting of glycerol, xylitol, erythritol, and combinations thereof. For example, the first component polyhydric alcohol (or more) of the organic treatment agent may be selected from the group consisting of glycerol, xylitol, and combinations thereof.

[0068] For example, the first component of the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from about 0.1% to about 1% by weight, based on the weight of the titanium dioxide particles. For example, the first component of the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from about 0.2% to about 0.9% by weight, based on the weight of the titanium dioxide particles. For example, the first component of the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from about 0.4% to about 0.7% by weight, based on the weight of the titanium dioxide particles.

[0069] For example, the second component of the organic treatment agent may be at least one carboxylic acid and / or a salt thereof. The carboxylic acid(s) and / or salt(s) may be selected from the group consisting of monocarboxylic acids, dicarboxylic acids, hydroxylcarboxylic acids, salts of monocarboxylic acids, salts of dicarboxylic acids, salts of hydroxylcarboxylic acids, and combinations thereof. For example, the carboxylic acid(s) and / or salt(s) may be selected from the group consisting of benzoic acid, adipic acid, propionic acid, citric acid, lactic acid, tartaric acid, salts of benzoic acid, salts of adipic acid, salts of propionic acid, salts of citric acid, salts of lactic acid, salts of tartaric acid, and combinations thereof. For example, the carboxylic acid(s) and / or salt(s) may be selected from the group consisting of benzoic acid, citric acid, lactic acid, salts of benzoic acid, salts of citric acid, salts of lactic acid, and combinations thereof. For example, the carboxylic acid(s) and / or salt(s) therefor may be selected from the group consisting of benzoic acid, lactic acid, salts of benzoic acid, salts of lactic acid, and combinations thereof.

[0070] For example, the second component of the organic treatment agent may be at least one alkanolamine. For example, the alkanolamine(s) may be selected from the group consisting of hydroxylamine, triisopropanolamine (TIPA), triethanolamine (TEOA), tris(hydroxymethyl)aminomethane, and combinations thereof. For example, the alkanolamine(s) may be selected from the group consisting of triisopropanolamine (TIPA), triethanolamine (TEOA), and combinations thereof. For example, the alkanolamine(s) may be triisopropanolamine (TIPA).

[0071] For example, the second component of the organic treatment agent may be at least one carboxylate and / or salt thereof, accompanied by one or more alkanolamines. For example, the carboxylic acid(s) and / or salt(s) thereof may be selected from the group described above. For example, the alkanolamine(s) may be selected from the group described above.

[0072] For example, the second component of the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from approximately 0.01% to approximately 0.8% by weight, based on the weight of the titanium dioxide particles. For example, the second component of the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from approximately 0.03% to approximately 0.5% by weight, based on the weight of the titanium dioxide particles. For example, the second component of the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from approximately 0.05% to approximately 0.4% by weight, based on the weight of the titanium dioxide particles.

[0073] For example, if the second component of the organic treatment agent is one or more carboxylic acids or salts thereof, it may be deposited on the surface of the pigment particles in an amount ranging from about 0.1% to about 0.6% by weight, based on the weight of the titanium dioxide particles. For example, if the second component of the organic treatment agent is one or more carboxylic acids or salts thereof, it may be deposited on the surface of the pigment particles in an amount ranging from about 0.15% to about 0.5% by weight, based on the weight of the titanium dioxide particles. For example, if the second component of the organic treatment agent is one or more carboxylic acids or salts thereof, it may be deposited on the surface of the pigment particles in an amount ranging from about 0.2% to about 0.4% by weight, based on the weight of the titanium dioxide particles.

[0074] For example, if the second component of the organic treatment agent is one or more alkanolamines, it may be deposited on the surface of the pigment particles in an amount ranging from about 0.01% to about 0.2% by weight, based on the weight of the titanium dioxide particles. For example, if the second component of the organic treatment agent is one or more alkanolamines, it may be deposited on the surface of the pigment particles in an amount ranging from about 0.02% to about 0.16% by weight, based on the weight of the titanium dioxide particles. For example, if the second component of the organic treatment agent is one or more alkanolamines, it may be deposited on the surface of the pigment particles in an amount ranging from about 0.04% to about 0.12% by weight, based on the weight of the titanium dioxide particles.

[0075] In one embodiment, the treated titanium dioxide further comprises an inorganic treatment agent that is deposited on the surface of the titanium dioxide particles to form a coating of the inorganic treatment agent thereon. For example, an organic treatment agent may be deposited on top of the coating of the inorganic treatment agent.

[0076] For example, the first inorganic treatment agent may be deposited on the surface of titanium dioxide particles to form a coating of the first inorganic treatment agent, and the second inorganic treatment agent may be deposited on top of the coating of the first inorganic treatment agent to form a coating of the second inorganic treatment agent. For example, the organic treatment agent may be deposited on top of the coating of the second inorganic treatment agent.

[0077] The inorganic treatment agent(s) may be any of the inorganic treatment agents(s) described above in relation to the processes disclosed herein. For example, the inorganic treatment agent(s) may be deposited on the surface of the titanium dioxide particles in an amount ranging from about 0.1% to about 15% by weight, based on the combined weight of the titanium dioxide particles and the inorganic coating(s). For example, the inorganic treatment agent(s) may be deposited on the surface of the titanium dioxide particles in an amount ranging from about 0.5% to about 10% by weight, based on the weight of the titanium dioxide particles.

[0078] For example, in one embodiment, the above-described organic treatment agent is a second organic treatment agent, and the treated titanium dioxide dye further comprises a first organic treatment agent which is deposited on the surface of the dye particles to form a coating of the first organic treatment agent thereon. For example, the second organic treatment agent may be deposited on top of the first organic treatment agent.

[0079] For example, the first organic treatment agent may be selected from the group consisting of alkylphosphinic acid, alkylphosphinic acid derivatives, phosphonic acid, phosphonic acid derivatives, siloxane, and combinations thereof.

[0080] Examples of usable alkylphosphinic acids and alkylphosphinic acid derivatives include bis(2,4,4-trimethylpentyl)phosphinic acid, bis(2-ethylhexylphosphinic acid), oleylphosphinic acid, n-octadecylphosphinic acid, phosphinic acid esters, and combinations thereof. An example of a usable phosphinic acid ester is bis(2-ethylhexyl)phosphinic acid 2-ethylhexyl ester.

[0081] Examples of usable phosphonic acids and derivatives of phosphonic acids include n-octylphosphonic acid, decylphosphonic acid, dodecylphosphonic acid, octylphosphonic acid, phosphonic acid esters, phosphonic acid salts, and combinations thereof. Examples of usable phosphonic acid esters include alkylphosphonic acid esters. An example of a usable phosphonic acid salt is the monoethyl potassium salt.

[0082] Examples of usable siloxanes include polydimethylsiloxane, copolymers of polydimethylsiloxane and polymethylhydrogensiloxane, n-octyltriethoxysilane, silicone alkyl polyethers, silicone polyether carboxylates, and combinations thereof.

[0083] For example, the first organic treatment agent may be selected from the group consisting of alkylphosphinic acids, phosphonic acids, siloxanes, and combinations thereof. For example, the first organic treatment agent may consist of one or more alkylphosphinic acids. For example, the first organic treatment agent may be bis(2,4,4-trimethylpentyl)phosphinic acid.

[0084] For example, the first organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from about 0.05% to about 1.0% by weight, based on the weight of the titanium dioxide particles. For example, the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from about 0.1% to about 0.8% by weight, based on the weight of the titanium dioxide particles. For example, the organic treatment agent may be deposited on the surface of the pigment particles in an amount ranging from about 0.2% to about 0.6% by weight, based on the weight of the titanium dioxide particles.

[0085] The treated titanium dioxide may be formed by the processes disclosed herein.

[0086] For example, in one embodiment, the process disclosed herein includes providing a plurality of titanium dioxide dye particles and depositing an organic treatment agent on the surface of the dye particles to form a coating of the organic treatment agent thereon. In this embodiment, the organic treatment agent includes a first component consisting of at least one polyhydric alcohol selected from the group consisting of glycerol, polyglycerol, mannitol, xylitol, erythritol, and combinations thereof, and a second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof, wherein the ratio of the first component to the second component in the treatment agent is in the range of about 1:1 to about 20:1.

[0087] For example, in another embodiment, the process disclosed herein includes providing a plurality of titanium dioxide dye particles and depositing an organic treatment agent on the surface of the dye particles to form a coating of the organic treatment agent thereon. In this embodiment, the organic treatment agent includes a first component consisting of at least one polyhydric alcohol selected from the group consisting of glycerol, polyglycerol, mannitol, xylitol, erythritol, and combinations thereof, and a second component selected from the group consisting of carboxylic acids and their salts, wherein the carboxylic acid and / or salt thereof is selected from the group consisting of benzoic acid, adipic acid, propionic acid, citric acid, lactic acid, tartaric acid, salts of benzoic acid, salts of adipic acid, salts of propionic acid, salts of citric acid, salts of lactic acid, salts of tartaric acid, and combinations thereof.

[0088] For example, in another embodiment, the process disclosed herein includes providing a plurality of titanium dioxide dye particles and depositing an organic treatment agent on the surface of the dye particles to form a coating of the organic treatment agent thereon. In this embodiment, the organic treatment agent includes a first component consisting of at least one polyhydric alcohol selected from the group consisting of glycerol, polyglycerol, mannitol, xylitol, erythritol, and combinations thereof, and a second component selected from the group consisting of carboxylic acids and their salts, wherein the carboxylic acid and / or its salt is selected from the group consisting of benzoic acid and its salts.

[0089] For example, in another embodiment, the process disclosed herein includes providing a plurality of titanium dioxide dye particles and depositing an organic treatment agent on the surface of the dye particles to form a coating of the organic treatment agent thereon. In this embodiment, the organic treatment agent includes a first component consisting of at least one polyhydric alcohol selected from the group consisting of glycerol, polyglycerol, mannitol, xylitol, erythritol, and combinations thereof, and a second component which is at least one alkanolamine.

[0090] For example, in another embodiment, the process disclosed herein includes providing a plurality of titanium dioxide dye particles and depositing an organic treatment agent on the surface of the dye particles to form a coating of the organic treatment agent thereon. In this embodiment, the organic treatment agent includes a first component consisting of at least one polyhydric alcohol selected from the group consisting of glycerol, polyglycerol, mannitol, xylitol, erythritol, and combinations thereof, and a second component which is an alkanolamine selected from the group consisting of hydroxylamine, triisopropanolamine (TIPA), triethanolamine (TEOA), tris(hydroxymethyl)aminomethane, and combinations thereof.

[0091] For example, in another embodiment, the process disclosed herein includes providing a plurality of titanium dioxide dye particles and depositing an organic treatment agent on the surface of the dye particles to form a coating of the organic treatment agent thereon. In this embodiment, the organic treatment agent includes a first component consisting of at least one polyhydric alcohol selected from the group consisting of glycerol, polyglycerol, mannitol, xylitol, erythritol, and combinations thereof, and a second component which is an alkanolamine, which is triisopropanolamine (TIPA).

[0092] For example, in one embodiment, the process disclosed herein includes providing a plurality of titanium dioxide dye particles, depositing a first organic treatment agent on the surface of the dye particles to form a coating of the first organic treatment agent, and depositing a second organic treatment agent on the surface of the dye particles to form a coating of the organic treatment agent. In this embodiment, the second organic treatment agent includes a first component consisting of at least one polyhydric alcohol, and a second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof.

[0093] For example, in another embodiment, the process disclosed herein includes: providing a plurality of titanium dioxide dye particles; depositing a first organic treatment agent on the surface of the dye particles to form a coating of the first organic treatment agent thereon; and depositing a second organic treatment agent on the surface of the dye particles to form a coating of the organic treatment agent thereon. In this embodiment, the first organic treatment agent is selected from the group consisting of alkylphosphinic acid, derivatives of alkylphosphinic acid, phosphonic acid, derivatives of phosphonic acid, siloxane, and combinations thereof. The second organic treatment agent includes a first component consisting of at least one polyhydric alcohol, and a second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof.

[0094] For example, in another embodiment, the process disclosed herein includes providing a plurality of titanium dioxide dye particles, depositing a first organic treatment agent on the surface of the dye particles to form a coating of the first organic treatment agent, and depositing a second organic treatment agent on the surface of the dye particles to form a coating of the organic treatment agent. In this embodiment, the first organic treatment agent is selected from the group consisting of alkylphosphinic acids, phosphonic acids, siloxanes, and combinations thereof. The second organic treatment agent includes a first component consisting of at least one polyhydric alcohol, and a second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof.

[0095] For example, in another embodiment, the process disclosed herein includes providing a plurality of titanium dioxide dye particles, depositing a first organic treatment agent on the surface of the dye particles to form a coating of the first organic treatment agent, and depositing a second organic treatment agent on the surface of the dye particles to form a coating of the organic treatment agent. In this embodiment, the first organic treatment agent consists of one or more alkylphosphinic acids. The second organic treatment agent includes a first component consisting of at least one polyhydric alcohol, and a second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof.

[0096] For example, in another embodiment, the process disclosed herein includes providing a plurality of titanium dioxide dye particles, depositing a first organic treatment agent on the surface of the dye particles to form a coating of the first organic treatment agent, and depositing a second organic treatment agent on the surface of the dye particles to form a coating of the organic treatment agent. In this embodiment, the first organic treatment agent is bis(2,4,4-trimethylpentyl)phosphinic acid. The second organic treatment agent includes a first component consisting of at least one polyhydric alcohol, and a second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof.

[0097] In one embodiment, the treated titanium dioxide dye comprises a plurality of titanium dioxide dye particles and an organic treatment agent deposited on the surface of the titanium dioxide dye particles to form a coating thereon. In this embodiment, the organic treatment agent comprises a first component consisting of at least one polyhydric alcohol selected from the group consisting of glycerol, polyglycerol, mannitol, xylitol, erythritol, and combinations thereof, and a second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof, wherein the ratio of the first component to the second component in the treatment agent is in the range of about 1:1 to about 20:1.

[0098] In one embodiment, the treated titanium dioxide dye comprises a plurality of titanium dioxide dye particles and an organic treatment agent deposited on the surface of the titanium dioxide dye particles to form a coating thereon. In this embodiment, the organic treatment agent comprises a first component consisting of at least one polyhydric alcohol selected from the group consisting of glycerol, polyglycerol, mannitol, xylitol, erythritol, and combinations thereof, and a second component selected from the group consisting of carboxylic acids and their salts, wherein the carboxylic acid and / or salt thereof is selected from the group consisting of benzoic acid, adipic acid, propionic acid, citric acid, lactic acid, tartaric acid, salts of benzoic acid, salts of adipic acid, salts of propionic acid, salts of citric acid, salts of lactic acid, salts of tartaric acid, and combinations thereof.

[0099] In one embodiment, the treated titanium dioxide dye comprises a plurality of titanium dioxide dye particles and an organic treatment agent deposited on the surface of the titanium dioxide dye particles to form a coating thereon. In this embodiment, the organic treatment agent comprises a first component consisting of at least one polyhydric alcohol selected from the group consisting of glycerol, polyglycerol, mannitol, xylitol, erythritol, and combinations thereof, and a second component selected from the group consisting of carboxylic acids and their salts, wherein the carboxylic acid and / or its salt is selected from the group consisting of benzoic acid and its salts.

[0100] In one embodiment, the treated titanium dioxide dye comprises a plurality of titanium dioxide dye particles and an organic treatment agent deposited on the surface of the titanium dioxide dye particles to form a coating thereon. In this embodiment, the organic treatment agent comprises a first component consisting of at least one polyhydric alcohol selected from the group consisting of glycerol, polyglycerol, mannitol, xylitol, erythritol, and combinations thereof, and a second component which is at least one alkanolamine.

[0101] In one embodiment, the treated titanium dioxide dye comprises a plurality of titanium dioxide dye particles and an organic treatment agent deposited on the surface of the titanium dioxide dye particles to form a coating thereon. In this embodiment, the organic treatment agent comprises a first component consisting of at least one polyhydric alcohol selected from the group consisting of glycerol, polyglycerol, mannitol, xylitol, erythritol, and combinations thereof, and a second component which is an alkanolamine selected from the group consisting of hydroxylamine, triisopropanolamine (TIPA), triethanolamine (TEOA), tris(hydroxymethyl)aminomethane, and combinations thereof.

[0102] In one embodiment, the treated titanium dioxide dye comprises a plurality of titanium dioxide dye particles and an organic treatment agent deposited on the surface of the titanium dioxide dye particles to form a coating thereon. In this embodiment, the organic treatment agent comprises a first component consisting of at least one polyhydric alcohol selected from the group consisting of glycerol, polyglycerol, mannitol, xylitol, erythritol, and combinations thereof, and a second component which is an alkanolamine, which is triisopropanolamine (TIPA).

[0103] For example, in another embodiment, the treated titanium dioxide dye disclosed herein comprises a plurality of titanium dioxide dye particles, a first organic treatment agent deposited on the surface of the dye particles to form a coating of the first organic treatment agent thereon, and a second organic treatment agent deposited on the surface of the dye particles to form a coating of the organic treatment agent thereon. In this embodiment, the first organic treatment agent is selected from the group consisting of alkylphosphinic acids, derivatives of alkylphosphinic acids, phosphonic acids, derivatives of phosphonic acids, siloxanes, and combinations thereof. The second organic treatment agent comprises a first component consisting of at least one polyhydric alcohol, and a second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof.

[0104] For example, in another embodiment, the treated titanium dioxide dye disclosed herein comprises a plurality of titanium dioxide dye particles, a first organic treatment agent deposited on the surface of the dye particles to form a coating of the first organic treatment agent thereon, and a second organic treatment agent deposited on the surface of the dye particles to form a coating of the organic treatment agent thereon. In this embodiment, the first organic treatment agent is selected from the group consisting of alkylphosphinic acids, phosphonic acids, siloxanes, and combinations thereof. The second organic treatment agent comprises a first component consisting of at least one polyhydric alcohol, and a second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof.

[0105] For example, in another embodiment, the treated titanium dioxide dye disclosed herein comprises a plurality of titanium dioxide dye particles, a first organic treatment agent deposited on the surface of the dye particles to form a coating of the first organic treatment agent thereon, and a second organic treatment agent deposited on the surface of the dye particles to form a coating of the organic treatment agent thereon. In this embodiment, the first organic treatment agent comprises one or more alkylphosphinic acids. The second organic treatment agent comprises a first component comprising at least one polyhydric alcohol, and a second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof.

[0106] For example, in another embodiment, the treated titanium dioxide dye disclosed herein comprises a plurality of titanium dioxide dye particles, a first organic treatment agent deposited on the surface of the dye particles to form a coating of the first organic treatment agent thereon, and a second organic treatment agent deposited on the surface of the dye particles to form a coating of the organic treatment agent thereon. In this embodiment, the first organic treatment agent is bis(2,4,4-trimethylpentyl)phosphinic acid. The second organic treatment agent comprises a first component consisting of at least one polyhydric alcohol and a second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof.

[0107] In accordance with the processes disclosed herein and in connection with the titanium dioxide dyes disclosed herein, the organic treatment agents deposited on the surface of titanium dioxide dye particles act as grinding aids in the milling process, improving the flow and dispersion properties of the dye and, in other aspects, improving the performance of the dye. As a result, the organic treatment agents may provide an effective substitute for TMP in connection with the production of titanium dioxide dyes and the titanium dioxide particles produced. [Examples]

[0108] The treated titanium dioxide dyes formed by the processes disclosed herein and the treated titanium dioxide dyes disclosed herein are illustrated by the following examples.

[0109] Processing Example 1. Preparation of silica and alumina-treated titanium dioxide filtration cake. Particulate titanium dioxide pigment particles formed by a chlorine process were dispersed in water in the presence of 0.075% sodium hexametaphosphonate dispersant, along with a sufficient amount of sodium hydroxide to adjust the pH of the dispersion to 9.5 or higher, to achieve an aqueous dispersion with a solid content of 35%. The resulting slurry was subjected to sand milling (using a zircon sand to pigment weight ratio of 4:1) until 94% of the particles were smaller than 0.63 microns, as determined by a Microtrac X 100 particle size analyzer.

[0110] The resulting slurry was diluted to a 30% solid content, heated to 75°C, and then treated with 3.0% sodium silicate (calculated as silica relative to the weight of the final pigment) by adding sodium silicate over 20 minutes. While maintaining the temperature at 75°C, concentrated sulfuric acid was slowly added to slowly decrease the pH of the slurry to 5.5 over a period of 55 minutes. After digesting the slurry for 15 minutes, 1.6% sodium aluminate (calculated as alumina relative to the weight of the final pigment) was added to the slurry over 10 minutes. The pH of the slurry was maintained at 8.25-9.25 by simultaneously adding concentrated sulfuric acid. The slurry was digested at 75°C for 15 minutes, and then the pH of the slurry was adjusted to 6.2 with concentrated sulfuric acid. The slurry was then filtered while still hot. The resulting filtrate was washed with water preheated to 60°C. A wet titanium dioxide filtration cake treated with silica and alumina was obtained.

[0111] Processing Example 2. Preparation of zirconia and alumina-treated titanium dioxide filtration cake Particulate titanium dioxide pigment particles formed by a chlorine process were dispersed in water in the presence of 0.075% sodium hexametaphosphonate dispersant, along with a sufficient amount of sodium hydroxide to adjust the pH of the dispersion to 9.5 or higher, to achieve an aqueous dispersion with a solid content of 35%. The resulting slurry was subjected to sand milling (using a zircon sand to pigment weight ratio of 4:1) until 92% of the particles were smaller than 0.63 microns, as determined by a Microtrac X 100 particle size analyzer.

[0112] The resulting slurry was diluted to a 30% solid content, heated to 70°C, and the pH was adjusted to 3.5 with concentrated sulfuric acid. Next, the slurry was treated with 0.25% zirconium oxychloride (calculated as zirconium relative to the weight of the final dye) by adding zirconium oxychloride. After scalding the slurry for 15 minutes, 3.0% sodium aluminate (calculated as alumina relative to the weight of the final dye) was added to the slurry over a period of 20 minutes. The pH of the slurry was maintained at 8-8.5 by simultaneously adding concentrated sulfuric acid. Next, the slurry was scalded at 70°C for 15 minutes, and then the pH of the slurry was adjusted to 7.5 with concentrated sulfuric acid. The slurry was then filtered while still hot. The resulting filtrate was washed with water preheated to 60°C. A wet titanium dioxide filtration cake treated with zirconia and alumina was obtained.

[0113] Comparative Example 1. Dye preparation using TMP A 50% slurry was prepared by mixing 1000 g of dried pigment with an equivalent amount of moist titanium dioxide filtration cake derived from Treatment Example 1 using deionized water. Next, 10.61 g of 33% trimethylolpropane (TMP) aqueous solution was added to the slurry and thoroughly mixed. The TMP-treated titanium dioxide slurry was then dried in an oven at 115°C to a moisture content of less than 1%. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 1.8:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi. The particle size distribution of the finished pigment was determined by a Microtrac X 100 particle size analyzer and reported as 0.63 microns in %Pass.

[0114] Comparative Example 2. Dye preparation with glycerol A 50% slurry was prepared by mixing 1000 g of dried pigment with an equivalent amount of moist titanium dioxide filtration cake derived from Treatment Example 1 using deionized water. Next, 5.0 g of glycerol was added to the slurry and thoroughly mixed. The glycerol-treated titanium dioxide slurry was then dried in an oven at 115°C to a moisture content of less than 1%. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 1.8:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi. The particle size distribution of the finished pigment was determined using a Microtrac X 100 particle size analyzer and reported as 0.63 microns in %Pass.

[0115] Comparative Example 3. Dye Preparation with Glycerol A 50% slurry was prepared by mixing 1000 g of dried pigment with a humid titanium dioxide filtration cake derived from Treatment Example 1 in an amount equivalent to that of dried pigment, using deionized water. Next, 7.0 g of glycerol was added to the slurry and thoroughly mixed. The glycerol-treated titanium dioxide slurry was then dried in an oven at 115°C to a moisture content of less than 1%. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 1.8:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi. The particle size distribution of the finished pigment was determined by a Microtrac X 100 particle size analyzer and reported as 0.63 microns in %Pass.

[0116] Claimed dye example 1. Dye preparation with glycerol and sodium benzoate An equivalent amount of moist titanium dioxide filtration cake derived from Treatment Example 1 was mixed with deionized water to provide a 50% slurry. Next, 3.5 g of sodium benzoate was dissolved in 10 g of deionized water and then mixed with 3.5 g of glycerol to provide a chemical mixture. The chemical mixture was then mixed with the titanium dioxide slurry. The treated titanium dioxide slurry was then dried in an oven at 115°C to a moisture content of less than 1%. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 1.8:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi. The particle size distribution of the finished pigment was determined by a Microtrac X 100 particle size analyzer and reported as 0.63 microns in %Pass.

[0117] Comparative Example 4. Dye preparation using TMP A 50% slurry was prepared by mixing 1000 g of dried pigment with an equivalent amount of moist titanium dioxide filtration cake derived from Treatment Example 2 using deionized water. Next, 10.61 g of 33% trimethylolpropane (TMP) aqueous solution was added to the slurry and thoroughly mixed. The TMP-treated titanium dioxide slurry was then dried in an oven at 115°C to a moisture content of less than 1%. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 1.8:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi. The particle size distribution of the finished pigment was determined by a Microtrac X 100 particle size analyzer and reported as 0.63 microns in %Pass.

[0118] Comparative Example 5. Dye Preparation with Glycerol A 50% slurry was prepared by mixing 1000 g of dried pigment with an equivalent amount of moist titanium dioxide filtration cake derived from Treatment Example 2 using deionized water. Next, 5.0 g of glycerol was added to the slurry and thoroughly mixed. The glycerol-treated titanium dioxide slurry was then dried in an oven at 115°C to a moisture content of less than 1%. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 1.8:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi. The particle size distribution of the finished pigment was determined using a Microtrac X 100 particle size analyzer and reported as 0.63 microns in %Pass.

[0119] Comparative Example 6. Dye Preparation with Glycerol A 50% slurry was prepared by mixing 1000 g of dried pigment with a humid titanium dioxide filtration cake derived from Treatment Example 2 in an equivalent amount, using deionized water. Next, 8.0 g of glycerol was added to the slurry and thoroughly mixed. The glycerol-treated titanium dioxide slurry was then dried in an oven at 115°C to a moisture content of less than 1%. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 1.8:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi. The particle size distribution of the finished pigment was determined using a Microtrac X 100 particle size analyzer and reported as 0.63 microns in %Pass.

[0120] Comparative Example 7. Dye Preparation with TIPA A 50% slurry was prepared by mixing 1000 g of dried pigment with a humid titanium dioxide filtration cake derived from Treatment Example 2 in an equivalent amount, using deionized water. Next, 5.9 g of 85% triisopropanolpropane (TIPA) solution was added to the slurry and thoroughly mixed. The TIPA-treated titanium dioxide slurry was then dried in an oven at 115°C to a moisture content of less than 1%. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 1.8:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi. The particle size distribution of the finished pigment was determined by a Microtrac X 100 particle size analyzer and reported as 0.63 microns in %Pass.

[0121] Claimed dye example 2. Dye preparation with glycerol and triisopropanolamine (TIPA). A 50% slurry was prepared by mixing 1000 g of dried pigment with a wet titanium dioxide filtration cake from Treatment Example 2 in an equivalent amount, using deionized water. Next, 1.2 g of 85% TIPA solution was mixed with 5.0 g of deionized water and 5.0 g of glycerol to prepare a chemical mixture. This chemical mixture was then mixed with the titanium dioxide slurry. The treated titanium dioxide slurry was then dried in an oven at 115°C to a moisture content of less than 1%. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 1.8:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi. The particle size distribution of the finished pigment was determined by a Microtrac X 100 particle size analyzer and reported as 0.63 microns in %Pass.

[0122] Test Example 1: Paint gloss and tint strength test of water-based acrylic paint formulations In each test, samples and standards were prepared in the same formulation as shown in Table 1. Both paints were then drawn side-by-side on a Lenata card. A gloss meter was used to measure the gloss of the dried film from reflected light at a 60-degree angle. An integrating sphere spectrophotometer was used to measure the CIE L* and b* values ​​of the dried paint, and these values ​​were used to calculate the tint intensity and tint tone. Table 1. Aqueous acrylic coating formulations used in gloss and tint strength tests. [Table 1] The tint strength was calculated using the Kubelka-Munk equation:

number

number

[0123] Test Example 2: Dye Alkyd Resin Dispersion Test Solvent-borne alkyd resin paints were prepared as shown in Table 2. The paints were drawn and spread on a Hegman gauge. The dispersion fineness of the alkyd resin (grinding line in microns) was measured, and the cleanliness of the alkyd resin dispersion (nib count) was read as the number of nibs on the grinding line. Table 2. Solvent-soluble alkyd resin coating formulations used in the dye alkyd resin dispersion test. [Table 2]

[0124] The paint test results for the titanium dioxide finishing pigments described in the above examples are listed in Tables 3 and 4 below. Table 3. Paint test results for silica and alumina-treated TiO2 [Table 3] Table 4. Paint test results for zirconia and alumina-treated TiO2 [Table 4]

[0125] As shown in Tables 3 and 4, the samples prepared with glycerol alone exhibited a larger particle size distribution, lower gloss and tint intensity, and inferior alkyd resin dispersion compared to the standard control using TMP. On the other hand, the samples prepared with glycerol and sodium benzoate (Claim Dye Example 1), and the samples prepared with glycerol and TIPA (Claim Dye Example 2), yielded results comparable to the standard control.

[0126] As mentioned above, the TMP Consortium, which is related to the European Union's Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) regulations, has voluntarily classified TMP as potentially reproductively toxic. On the other hand, the organic chemicals used to form claimed dye examples 1 and 2 are either direct food additives (glycerol and sodium benzoate) or are considered safe in indirect food contact (TIPA).

[0127] Processing Example 3. Preparation of alumina-treated titanium dioxide filtration cake Particulate titanium dioxide pigment particles formed by a chlorine process were dispersed in water in the presence of 0.1% sodium hexametaphosphonate dispersant, along with a sufficient amount of sodium hydroxide to adjust the pH of the dispersion to 9.5 or higher, to achieve an aqueous dispersion with a solid content of 35%. The resulting slurry was subjected to sand milling (using a zircon sand to pigment weight ratio of 4:1) until 90% of the particles were smaller than 0.63 microns, as determined by a Microtrac X 100 particle size analyzer.

[0128] The resulting slurry was diluted to a 30% solid content and heated to 60°C. Next, the pH of the slurry was adjusted to 2.0 with concentrated sulfuric acid, and 1.0% sodium aluminate (calculated as alumina relative to the weight of the final dye) was added to the slurry. The slurry was sieved for 15 minutes, and the pH of the slurry was adjusted to 6.0 with concentrated sulfuric acid. The slurry was then filtered while still hot. The resulting filtrate was washed with water preheated to 60°C. A wet titanium dioxide filtration cake treated with alumina was obtained.

[0129] Comparative Example 8. Dye prepared with TMP A 50% slurry was prepared by mixing 1000 g of dried pigment with an equivalent amount of moist titanium dioxide filtration cake derived from Treatment Example 3 using deionized water. Next, 10.61 g of 33% trimethylolpropane (TMP) aqueous solution was added to the slurry and thoroughly mixed. The TMP-treated titanium dioxide slurry was then dried in an oven at 115°C to a moisture content of less than 1%. The dried pigment was crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 1.8:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi. The particle size distribution of the finished pigment was determined by a Microtrac X 100 particle size analyzer and reported as 0.63 microns in %Pass.

[0130] Comparative Example 9. Dye Preparation with Glycerol A 50% slurry was prepared by mixing 1000 g of dried pigment with a humid titanium dioxide filtration cake derived from Treatment Example 9 in an equivalent amount, using deionized water. Next, 5.0 g of glycerol was added to the slurry and thoroughly mixed. The glycerol-treated titanium dioxide slurry was then dried in an oven at 115°C to a moisture content of less than 1%. The dried pigment was crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 1.8:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi. The particle size distribution of the finished pigment was determined by a Microtrac X 100 particle size analyzer and reported as 0.63 microns in %Pass.

[0131] Claimed dye example 3. Dye preparation with glycerol and triisopropanolamine (TIPA). A 50% slurry was prepared by mixing 1000 g of dried pigment with a wet titanium dioxide filtration cake from Treatment Example 3 in an equivalent amount to deionized water. Next, 0.59 g of 85% TIPA solution was mixed with 5.0 g of deionized water and 5.5 g of glycerol to prepare a chemical mixture. This chemical mixture was then mixed with the titanium dioxide slurry. The treated titanium dioxide slurry was then dried in an oven at 115°C to a moisture content of less than 1%. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 1.8:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi. The particle size distribution of the finished pigment was determined by a Microtrac X 100 particle size analyzer and reported as 0.63 microns in %Pass.

[0132] Claimed dye example 4. Dye preparation with glycerol and triisopropanolamine (TIPA) A 50% slurry was prepared by mixing 1000 g of dried pigment with a wet titanium dioxide filtration cake from Treatment Example 3 in an equivalent amount to deionized water. Next, 1.18 g of 85% TIPA solution was mixed with 5.0 g of deionized water and 5.0 g of glycerol to prepare a chemical mixture. This chemical mixture was then mixed with the titanium dioxide slurry. The treated titanium dioxide slurry was then dried in an oven at 115°C to a moisture content of less than 1%. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 1.8:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi. The particle size distribution of the finished pigment was determined by a Microtrac X 100 particle size analyzer and reported as 0.63 microns in %Pass.

[0133] Claimed dye example 5. Dye preparation with glycerol and triisopropanolamine (TIPA) A 50% slurry was prepared by mixing 1000 g of dried pigment with a wet titanium dioxide filtration cake from Treatment Example 3 in an equivalent amount to deionized water. Next, 1.76 g of 85% TIPA solution was mixed with 5.0 g of deionized water and 4.5 g of glycerol to prepare a chemical mixture. This chemical mixture was then mixed with the titanium dioxide slurry. The treated titanium dioxide slurry was then dried in an oven at 115°C to a moisture content of less than 1%. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 1.8:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi. The particle size distribution of the finished pigment was determined by a Microtrac X 100 particle size analyzer and reported as 0.63 microns in %Pass.

[0134] Claimed dye example 6. Dye preparation with glycerol and triisopropanolamine (TIPA) (high TIPA dose) A 50% slurry was prepared by mixing 1000 g of dried pigment with a wet titanium dioxide filtration cake from Treatment Example 3 in an equivalent amount to deionized water. Next, 2.35 g of 85% TIPA solution was mixed with 5.0 g of deionized water and 4.0 g of glycerol to obtain a chemical mixture. The chemical mixture was then mixed with the titanium dioxide slurry. The treated titanium dioxide slurry was then dried in an oven at 115°C to a moisture content of less than 1%. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 1.8:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi. The particle size distribution of the finished pigment was determined by a Microtrac X 100 particle size analyzer and reported as 0.63 microns in %Pass.

[0135] Test Example 3: Plastic Optical Testing in Low-Density Polyethylene (LDPE) In each test, a Brabender mixing bowl fitted with a cam blade was heated to 100°C. Next, 55.0 g of black concentrate, 0.5 g of zinc stearate, 0.4 g of polymeric processing additive (BYK P-4102), and 2.50 g of the titanium dioxide dye sample to be tested were placed in a cup. The Brabender mixing bowl was started, and the contents of the cup were poured into the bowl using the chute and ram. The ram was held down using weight for approximately 2 minutes to allow the sample to fuse. The chute and ram were removed, the cover of the Brabender bowl was closed, and the contents were allowed to continue mixing for 6 minutes. The plastic mixture was then removed from the Brabender bowl and placed between the ferroplates inside the mold. The mold was immediately pressed at 10,000 psi for 1 minute. The sample was then cooled and removed from the mold. L*, a*, and b* were read, and the tint intensity and tint tone were calculated based on the test standards run with each batch.

[0136] The results of the comparative examples 8 and 9, as well as the requested dye examples 3 to 6, are shown in Table 5 below.

[0137] Test Example 4: Plastic Equilibrium Torque and Screen Pack Test in Linear Low-Density Polyethylene (LLDPE) Further tests were conducted on comparative examples 8 and 9, as well as the requested dye examples 3 to 6, as described above.

[0138] First, in each test, 109.5 g of the dye to be tested was mixed with 36.5 g of linear low-density polyethylene (LLDPE) (DOW 9820) to prepare a 75% titanium dioxide-containing LLDPE concentrate. The mixture was then thoroughly mixed by masticating the components in an ATR Plasti-Corder (CW Brabender Instruments, Inc.) mixing bowl at 100°C and a mixing speed of 100 rpm.

[0139] Next, instantaneous torque and temperature values ​​were recorded over a 9-minute period to ensure that equilibrium mixing conditions were achieved. The equilibrium torque value was determined by averaging the lowest measured instantaneous torque values ​​over a 1-minute period before and after the achievement of the lowest mixing conditions.

[0140] Next, 100 g of the 75% concentrate was extruded through a 350-mesh screen filter using a 0.75-inch barrel and 25:1 length-to-diameter extruder attached to the aforementioned ATR Plasticorder at an average processing temperature of approximately 190°C and 75 rpm. The amount of inorganic residue remaining on the 350-mesh screen filter, reported as the pigment grid content in parts per million based on the amount of pigment, was measured by gravimetric method by heating the extruded screen in a muffle furnace at 700°C for 10 minutes. The screen was then cooled to room temperature, and the weight of the screen was subsequently measured and compared to its weight before use.

[0141] The results of these further tests conducted on comparative examples 8 and 9, as well as on the requested dye examples 3-6, are shown in Table 5 below. Table 5. Test results of its application in alumina-treated TiO2 and plastics. [Table 5]

[0142] As shown in Table 5, when glycerol alone was used to replace TMP, the particle size of alumina-treated titanium dioxide was inferior to that of the TMP control, and there was also more screen pack residue. As shown, TIPA of 0.05% or more significantly improved grinding during refinement and can lead to particle size and screen pack residue comparable to that of the TMP control. When the amount of TIPA used was 0.2% or more, the material became very prone to sticking to the instrument blades when applied in LDPE, and the equilibrium torque in LLDPE was also significantly higher; nevertheless, the corresponding titanium dioxide dye performed very well overall.

[0143] Processing Example 4. Preparation of phosphate and alumina-treated titanium dioxide filtration cake Particulate titanium dioxide dye particles formed by a chlorine process were dispersed in water to form a raw slurry with a pH of 3-4. The resulting slurry was then subjected to sand milling (using a zircon sand to dye weight ratio of 4:1) until 90% of the particles were smaller than 0.63 microns (as determined by a Microtrac X 100 particle size analyzer), resulting in an aqueous dispersion with a solid content of 35%.

[0144] The resulting slurry was diluted to a 30% solid content, heated to 70°C, and the pH was adjusted to 1.0-1.5 with concentrated hydrochloric acid. Next, 0.4% sodium hexametaphosphate (calculated as P2O5 relative to the weight of the final dye) was added to the slurry. After scalding the slurry for 5 minutes, 1.0% sodium aluminate (calculated as alumina relative to the weight of the final dye) was added to the slurry. After scalding the slurry for 5 minutes, the pH of the slurry was adjusted to 4.7 with sodium hydroxide solution.

[0145] Next, the slurry was digested for 60 minutes, and the pH of the slurry was adjusted to 6.4 with a sodium hydroxide solution. Then, the slurry was digested for another 10 minutes, and then filtered while still hot. The resulting filtrate was washed with water that had been preheated to 60°C. A wet titanium dioxide filtration cake treated with phosphate and alumina was obtained.

[0146] Comparative Example 10. Dyes prepared with BIS and TMP An equivalent amount of moist titanium dioxide filtration cake derived from Treatment Example 4 was mixed with deionized water to form a paste. Next, 3.00 g of bis(2,4,4-trimethylpentyl)phosphinic acid (BIS) was added to the paste and thoroughly mixed. The treated titanium dioxide paste was then dried in an oven at 115°C to form a filtration cake with a moisture content of less than 1%. Next, 8.48 g of 33% trimethylolpropane (TMP) aqueous solution was sprayed onto the dry filtration cake. The dried pigment was crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 2.5:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi.

[0147] Comparative Example 11. Dye preparation with BIS and glycerol An equivalent amount of moist titanium dioxide filtration cake derived from Treatment Example 4, along with 1000 g of dried pigment, was mixed with deionized water to form a paste. Next, 3.00 g of bis(2,4,4-trimethylpentyl)phosphinic acid (BIS) was added to the paste and thoroughly mixed. The treated titanium dioxide paste was then dried in an oven at 115°C to form a filtration cake with a moisture content of less than 1%. Next, 4.00 g of glycerol was mixed with the dry filtration cake. The dried pigment was crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 2.5:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi.

[0148] Claimed dye example 7. Dye preparation with BIS, glycerol, and TIPA. An equivalent amount of moist titanium dioxide filtration cake derived from Treatment Example 4 was mixed with deionized water to form a paste. Next, 3.00 g of bis(2,4,4-trimethylpentyl)phosphinic acid (BIS) was added to the paste and thoroughly mixed. The treated titanium dioxide paste was then dried in an oven at 115°C to form a filtration cake with a moisture content of less than 1%. Next, 3.00 g of glycerol and 1.00 g of 85% TIPA mixture were added to the dry filtration cake. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 2.5:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi.

[0149] Claimed dye example 8. Dye preparation with BIS, glycerol, and sodium benzoate An equivalent amount of moist titanium dioxide filtration cake derived from Treatment Example 4, along with 1000 g of dried pigment, was mixed with deionized water to form a paste. Next, 3.00 g of bis(2,4,4-trimethylpentyl)phosphinic acid (BIS) was added to the paste and thoroughly mixed. The treated titanium dioxide paste was then dried in an oven at 115°C to form a filtration cake with a moisture content of less than 1%. Next, 2.00 g of sodium benzoate was dissolved in 10 g of deionized water and mixed with 2.00 g of glycerol to provide a chemical mixture. The chemical mixture was then added to the dry filtration cake. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 2.5:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi.

[0150] The test results for comparative examples 10 and 11, and the claim dye examples 7 and 8 are shown in Table 6 below. Table 6. Tests of its application in phosphate and alumina-treated TiO2 and plastics. [Table 6]

[0151] As shown in Table 6, when glycerol alone was used to replace TMP, both equilibrium torque and screen pack residue were higher than the control. On the other hand, when a blend of 0.3% glycerol and 0.1% TIPA (claimed dye example 8) and a blend of 0.2% glycerol and 0.2% sodium benzoate (claimed dye example 9) were used to replace TMP, both equilibrium torque and screen pack residue were comparable to the control.

[0152] Test Example 5: DOE Experiment - Preparation of Graded Titanium Dioxide Treated with Silica and Alumina in Glycerol and Triisopropanolamine (TIPA) DOE experiments were conducted to study the effects of glycerol and TIPA on silica and alumina-treated titanium dioxide dyes.

[0153] In each test, a 50% slurry was prepared by mixing 1000 g of dry pigment with a corresponding amount of moist titanium dioxide filtration cake derived from Treatment Example 1 using deionized water. Based on the dry weight of titanium dioxide, a specific amount of organic composition containing TMP (Comparative Example 12) or a mixture of glycerol and TIPA (Claim Pigment Examples 10-15) was mixed into the slurry. The organically treated titanium dioxide slurry was then dried in an oven at 115°C to a moisture content of less than 1%. The dried pigment was crushed to obtain dry pigment powder. The dry pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 1.8:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi.

[0154] Next, regarding the performance in coatings, the finishing dyes (comparative example 12 and claim dye examples 10-15) were tested according to test examples 1 and 2 as described above. During the experiment, two-pair samples were prepared for each organic composition. The results shown in Table 7 below are the averages of the two-pair samples. Table 7. Tests of the application of glycerol / TIPA in silica and alumina-treated TiO2 and coatings. [Table 7]

[0155] Table 7 shows that the combination of glycerol and TIPA exhibits properties comparable to those of dyes prepared with TMP.

[0156] Processing Example 5. Preparation of titanium dioxide filtration cake without inorganic treatment. Titanium dioxide dye particles formed by a chlorine process were dispersed in water to form a raw material slurry with a pH of 3-4. The resulting slurry was then subjected to sand milling (using a zircon sand to dye weight ratio of 4:1) until 90% of the particles were smaller than 0.63 microns (as determined by a Microtrac X 100 particle size analyzer), resulting in an aqueous dispersion with a solid content of 35%.

[0157] Next, the resulting slurry was diluted to a 30% solid content, heated to 85°C, and the pH was adjusted to 7.0 with a sodium hydroxide solution. The slurry was then allowed to simmer for another 10 minutes, and then filtered while still hot. The resulting filtrate was washed with water preheated to 60°C. A wet titanium dioxide filtration cake without inorganic treatment was obtained.

[0158] Comparative Example 13. Dyes prepared with BIS and TMP An equivalent amount of moist titanium dioxide filtration cake derived from Treatment Example 5 was mixed with deionized water to form a paste. Next, 3.10 g of bis(2,4,4-trimethylpentyl)phosphinic acid (BIS) was added to the paste and thoroughly mixed. The treated titanium dioxide paste was then dried in an oven at 115°C to form a filtration cake with a moisture content of less than 1%. Next, 4.85 g of 33% trimethylolpropane (TMP) aqueous solution was sprayed onto the dry filtration cake. The dried pigment was crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 2.5:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi.

[0159] Claimed dye example 16. Dye preparation with BIS, glycerol, and TIPA. An equivalent amount of moist titanium dioxide filtration cake derived from Treatment Example 5 was mixed with deionized water to form a paste. Next, 3.10 g of bis(2,4,4-trimethylpentyl)phosphinic acid (BIS) was added to the paste and thoroughly mixed. The treated titanium dioxide paste was then dried in an oven at 115°C to form a filtration cake with a moisture content of less than 1%. Next, 1.00 g of glycerol and 0.71 g of 85% TIPA mixture were added to the dry filtration cake. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 2.5:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi.

[0160] Claimed dye example 17. Dye preparation with BIS, glycerol, and sodium benzoate An equivalent amount of moist titanium dioxide filtration cake derived from Treatment Example 5 was mixed with deionized water to form a paste. Next, 3.00 g of bis(2,4,4-trimethylpentyl)phosphinic acid (BIS) was added to the paste and thoroughly mixed. The treated titanium dioxide paste was then dried in an oven at 115°C to form a filtration cake with a moisture content of less than 1%. Next, 0.60 g of sodium benzoate was dissolved in 10 g of deionized water and mixed with 1.00 g of glycerol to provide a chemical mixture. The chemical mixture was then added to the dry filtration cake. The dried pigment was then crushed to obtain dried pigment powder. The dried pigment powder was then steam-micronized using a steam-to-pigment weight ratio of 2.5:1 with a steam injector pressure set to 160 psi and a micronizer ring pressure set to 118 psi.

[0161] The test results for Comparative Example 13, and for Claim Dye Examples 16 and 17, are shown in Table 8 below. Table 8. Tests of its application in inorganic treated TiO2 and plastics. [Table 8]

[0162] As shown in Table 8, when a blend of 0.1% glycerol and 0.06% TIPA (claimed dye example 16) and a blend of 0.1% glycerol and 0.06% sodium benzoate (claimed dye example 17) were used to replace TMP, both the equilibrium torque and screen pack residue were comparable to the control.

[0163] Accordingly, the above examples demonstrate that the organic treatment agent used in producing the treated titanium dioxide dye according to the process disclosed herein, and used in conjunction with the titanium dioxide dye disclosed herein, is comparable to TMP. The first and second components of the treatment agent work together synergistically to achieve excellent results.

[0164] For example, as shown in Tables 3, 4, 5, and 7 above, when glycerol alone is used, the particle size distribution of the finishing dye is unacceptable, and the performance of the dye during coating is poor. However, using a relatively small amount of carboxylic acid (or its salt) or alkanolamine results in a significant improvement in particle size and coating performance.

[0165] Accordingly, the dyes, compositions and methods are well adapted to achieve the purposes and advantages mentioned, as well as those inherent therein. Since the dyes, compositions and methods of the present invention can be modified and implemented in different but equivalent ways, which will be obvious to those skilled in the art who benefit from the discussion herein, the specific examples disclosed above are illustrative only. Therefore, it will be apparent that the specific exemplary examples disclosed above are modifiable or variable, and that all such variations are considered to be within the scope and spirit of the dyes, compositions and methods of the present invention. While the dyes, compositions and methods are described in terms of "comprising," "containing," "having," or "including" a variety of components or steps, the dyes, compositions and methods can also, in some examples, "essentially consist of" or "consist of" a variety of components and steps. Whenever numerical ranges with lower and upper limits are disclosed, any numerical values ​​and any included ranges that fall within the range are specifically disclosed. In particular, all ranges of values ​​disclosed herein (in the form of "about a to about b" or equivalently "approximately a to b" or equivalently "approximately a ~ b") shall be understood to refer to all numerical values ​​and ranges that fall within a broader range of values. Furthermore, terms in the claims shall have plain and general meanings unless otherwise explicitly defined by the patent holder.

Claims

1. A process for producing treated titanium dioxide dyes, To provide multiple titanium dioxide dye particles, The process involves depositing an organic treatment agent onto the surface of the dye particles and forming a coating of the organic treatment agent thereon. The organic treatment agent includes, A first component consisting of at least one polyhydric alcohol, A second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof, The process including the process described above.

2. The process according to claim 1, wherein the organic treatment agent is deposited on the surface of the pigment particles in an amount ranging from about 0.1 to about 1% by weight, based on the weight of the titanium dioxide particles.

3. The process according to claim 1, wherein the ratio of the first component to the second component in the treatment agent is in the range of about 1:1 to about 20:

1.

4. The process according to claim 1, wherein the polyhydric alcohol of the first component of the organic treatment agent is selected from the group consisting of glycerol, polyglycerol, mannitol, xylitol, erythritol, and combinations thereof.

5. The process according to claim 1, wherein the second component of the organic treatment agent is at least one carboxylic acid and / or a salt thereof.

6. The process according to claim 5, wherein the carboxylic acid and / or salt thereof is selected from the group consisting of monocarboxylic acids, dicarboxylic acids, hydroxylcarboxylic acids, salts of monocarboxylic acids, salts of dicarboxylic acids, salts of hydroxylcarboxylic acids, and combinations thereof.

7. The process according to claim 6, wherein the carboxylic acid and / or its salt is selected from the group consisting of benzoic acid, adipic acid, propionic acid, citric acid, lactic acid, tartaric acid, salts of benzoic acid, salts of adipic acid, salts of propionic acid, salts of citric acid, salts of lactic acid, salts of tartaric acid, and combinations thereof.

8. The process according to claim 7, wherein the carboxylic acid and / or its salt is selected from the group consisting of benzoic acid and its salts.

9. The process according to claim 1, wherein the second component of the organic treatment agent is at least one alkanolamine.

10. The process according to claim 9, wherein the alkanolamine is selected from the group consisting of hydroxylamine, triisopropanolamine (TIPA), triethanolamine (TEOA), tris(hydroxymethyl)aminomethane, and combinations thereof.

11. The process according to claim 10, wherein the alkanolamine is triisopropanolamine (TIPA).

12. The process according to claim 1, wherein the first component of the organic treatment agent is deposited on the surface of the dye particles in an amount ranging from about 0.1 to about 0.99% by weight based on the weight of the titanium dioxide particles, and the second component of the organic treatment agent is deposited on the surface of the dye particles in an amount ranging from about 0.01 to about 0.9% by weight based on the weight of the titanium dioxide particles.

13. The process according to claim 12, wherein the second component is at least one carboxylic acid and / or a salt thereof, deposited on the surface of the dye particles in an amount ranging from about 0.1 to about 0.6% by weight based on the weight of the titanium dioxide particles.

14. The process according to claim 12, wherein the second component is at least one alkanolamine, which is deposited on the surface of the dye particles in an amount ranging from about 0.01 to about 0.2% by weight based on the weight of the titanium dioxide particles.

15. Before depositing the organic treatment agent onto the surface of the dye particles, The step of depositing an inorganic treatment agent onto the surface of the dye particles and forming a coating of the inorganic treatment agent thereon. The process according to claim 1, further comprising:

16. The aforementioned organic treatment agent is a second organic treatment agent, and the process is, The step of depositing the first organic treatment agent onto the surface of the dye particles to form a coating of the first organic treatment agent thereon. The process according to claim 1, further comprising:

17. The process according to claim 16, wherein the first organic treatment agent is deposited on the surface of the pigment particles before the second organic treatment agent is deposited on the surface of the pigment particles.

18. The process according to claim 16, wherein the first organic treatment agent is selected from the group consisting of alkylphosphinic acid, derivatives of alkylphosphinic acid, phosphonic acid, derivatives of phosphonic acid, siloxane, and combinations thereof.

19. The process according to claim 18, wherein the first organic treatment agent is selected from the group consisting of alkylphosphinic acid, phosphonic acid, siloxane, and combinations thereof.

20. The process according to claim 10, wherein the first organic treatment agent comprises one or more alkylphosphinic acids.

21. The process according to claim 20, wherein the first organic acid is bis(2,4,4-trimethylpentyl)phosphinic acid.

22. The process according to claim 20, wherein the first treatment agent is deposited on the surface of the pigment particles in an amount ranging from about 0.05% to about 1.0% by weight, based on the weight of the pigment particles.

23. A treated titanium dioxide dye, Multiple titanium dioxide dye particles, The organic treatment agent is deposited on the surface of the titanium dioxide particles and forms a coating thereon. The organic treatment agent includes, A first component consisting of at least one polyhydric alcohol, A second component selected from the group consisting of carboxylic acids and their salts, alkanolamines, and combinations thereof, The treated titanium dioxide dye, including the above.

24. The dye according to claim 23, wherein the polyhydric alcohol of the first component of the organic treatment agent is selected from the group consisting of glycerol, polyglycerol, mannitol, xylitol, erythritol, and combinations thereof.

25. The dye according to claim 23, wherein the second component of the processing agent is at least one carboxylic acid and / or a salt thereof.

26. The dye according to claim 25, wherein the carboxylic acid and / or its salt is selected from the group consisting of benzoic acid, adipic acid, propionic acid, citric acid, lactic acid, tartaric acid, salts of benzoic acid, salts of adipic acid, salts of propionic acid, salts of citric acid, salts of lactic acid, salts of tartaric acid, and combinations thereof.

27. The dye according to claim 26, wherein the carboxylic acid and / or its salt is selected from the group consisting of benzoic acid and its salts.

28. The dye according to claim 23, wherein the second component of the processing agent is at least one alkanolamine.

29. The dye according to claim 28, wherein the alkanolamine is selected from the group consisting of hydroxylamine, triisopropanolamine (TIPA), triethanolamine (TEOA), tris(hydroxymethyl)aminomethane, and combinations thereof.

30. The dye according to claim 29, wherein the alkanolamine is triisopropanolamine (TIPA).

31. The dye according to claim 23, wherein the organic treatment agent is a second organic treatment agent, and the dye further comprises the first organic treatment agent which is deposited on the surface of the dye particles to form a coating of the first organic treatment agent thereon.

32. The dye according to claim 31, wherein the second organic treatment agent is deposited on the first organic treatment agent.

33. The process according to claim 31, wherein the first organic treatment agent is selected from the group consisting of alkylphosphinic acid, derivatives of alkylphosphinic acid, phosphonic acid, derivatives of phosphonic acid, siloxane, and combinations thereof.

34. The process according to claim 33, wherein the first organic treatment agent is selected from the group consisting of alkylphosphinic acid, phosphonic acid, siloxane, and combinations thereof.

35. The process according to claim 34, wherein the first organic treatment agent comprises one or more alkylphosphinic acids.

36. The process according to claim 35, wherein the first organic acid is bis(2,4,4-trimethylpentyl)phosphinic acid.

37. The process according to claim 31, wherein the first treatment agent is deposited on the surface of the pigment particles in an amount ranging from about 0.05% to about 1.0% by weight, based on the weight of the pigment particles.

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