MXPA97007940A - Process to prepare an improved pigment of low disintegration that flows libreme - Google Patents

Abstract

The present invention relates to: A process for preparing low disintegrating, easily dispersible, non-micronizing coated pigments, wherein the pigments are milled in an aqueous mixture, is then treated with a surfactant while being kept inside the a certain pH range and dehydrated by spray. The invention also provides the freely flowing pigments produced by this process

Description

PROCESS FOR. PREPARE AN IMPROVED PIGMENT OF LOW DISINTEGRATION THAT FLUSH FREELY BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for preparing low disintegrating, freely dispersible, dispersible pigments for use in paint and plastics compositions, and the pigments produced thereby. More specifically, the present invention relates to surface treatments, aqueous grinding, and spray drying of inorganic pigments to achieve low disintegration and good dispersibility without the expensive micronization step. More specifically, the present invention relates to the treatment of titanium dioxide pigments milled in sand with a surfactant prior to spray drying the pigenetto to eliminate the need for micronization or jet milling while maintaining good processability and dispersibility in waterborne resins. polyolefin. 2. Description of the Prior Art Pigments of titanium dioxide and other inorganic pigments normally produced and used in the paint, plastics or paper industry are generally in the form of a finely divided powder. The powders are usually milled or micronized as a final stage in their production. Jet milling contributes to dispersibility and brightness, but it is also a costly and intense energy stage. Jet-grind powders are inherently disintegrated and exhibit poor flow characteristics. Although free flowing powders with low disintegration can be obtained by spray drying, these powders generally exhibit poor pigment properties. In this way, the ultimate users of the pigments have generally had to choose between freely flowing, low-disintegration pigments, spray-dried pigments with poor pigment properties and jet-grind pigments with poor flow characteristics. Surface treatments of the pigments to achieve improved performance characteristics in plastic compositions are well known in the art. For example, US Pat. No. 4,986,853 discloses the coating of pearlescent pigments in sheet form with monocarboxylic acids or condensed cyclohexanone resins and a plasticizer, to improve flowability and reduce generation of dust. Additionally, U.S. Patent No. 4,762,523 discloses coating a wet pigment with a polyester surfactant, then adding mineral oil or wax to the pigment and applying intense shear to a freely flowing pigment, without permanently disintegrating. In U.S. Patent No. 4,563,221, the titanium dioxide pigments are coated with a combination of isostearic acid, dodecyl benzene sulfonic acid and a cationic emulsifying agent and then spray-dried without micronization to improve flowability and reduce the production of dust. Also in U.S. Patent No. 3,660,129, the titanium dioxide pigments are coated with hydrous oxides, then milled in sand and dewatered by spray to improve their fluidity. Additional examples of the surface treatment or coating of the pigments to improve processability include the coating processes described in U.S. Patent No. 4,514,231. This patent teaches the coating of an oxidic or silicate filler with an organosilicon emulsifier compound and is then dehydrated by spray to improve the reinforcing properties of the filler. Similarly, U.S. Patent No. 4,909,853 teaches the aqueous coating of the organic pigments and / or natural gas carbon black with a sulfosuccinic acid surfactant ester followed by spray drying to improve the dispersibility of the pigment in the thermoplastics. Also US Patent No. 4, 464,203 discloses the treatment of organic and inorganic pigments with an amine and an ethylene oxide block copolymer surfactant to improve pigment dispersibility and other properties in a variety of applications. U.S. Patent No. 4,156,616 discloses the treatment of organic and / or inorganic pigments with an alkylene oxide addition product of a long chain amine and an anionic surfactant with an aromatic moiety, to improve dispersibility. In US Pat. No. 4,056,402 the aqueous mixtures of the organic or inorganic pigments are milled in the presence of a dispersing agent of nonionic polyether alcohol and nonionic cellulose ether to reduce disintegration and improve dispersibility. Also in U.S. Patent No. 3,947,287, the aqueous organic and inorganic colored pigments are coated with the reaction product of a polyhydroxyl compound and a water retention agent to improve stability and performance. U.S. Patent No. 3,925,095 teaches the treatment of inorganic pigments or fillers with hydroxy alkylated diamino alkylene dispersing agent to improve the flowability and dispersibility in various applications. Other examples of pigment surface treatment and coating processes include the treatment process described in U.S. Patent No. 4,375,520. This patent teaches the production of dustless particles, including pigments, by treating the particles with a composition containing a solid polymer of low molecular weight and a liquid polymeric substance such as soybean oil expoxidized at temperatures above the melting point of the polymer. Also US Pat. No. 4,127,421 describes the aqueous treatment of a lead pigment containing chromate with a friable hydrocarbon resin and a cationic surfactant to produce free-flowing, non-disintegrating granules. In U.S. Patent No. 4,599,114 an aqueous mixture of titanium dioxide is treated with a surfactant formed from the reaction of a diamine, a carboxylic acid and a fatty acid to improve the dispersibility and processability of the pigment in various applications. U.S. Patent No. 5,228,912 teaches the treatment of pigment surfaces in the form of platelets with a polyacrylate, polymethacrylate or salts thereof, to improve the dispersibility in paints and printing inks. Also US Pat. No. 5,199,986 discloses a process wherein the inorganic pigment granules previously dehydrated by spray are coated with water and solutions of boron, aluminum, silicon, titanium, zinc, brass or tin salts to improve the processability and reduce the production of dust. U.S. Patent No. 5,266,622 teaches the production of aqueous dispersions of inorganic or organic pigments or fillers wherein the pigments or fillers are coated with a water-soluble polymer, a non-ionic alkylene oxide adduct, and other dispersants, to improve the flow properties and increase the stability of the pigment dispersion. Similarly, U.S. Patent No. 4,186,028 teaches the coating of various pigments and fillers with phosphonocarboxylic acid and / or a phosphonocarboxylic acid salt to produce dispersions of fluid, dispersible aqueous fillings or pigments. None of the aforementioned patents suggest or teach the process of compression grinding a mixture of aqueous pigment, treating the mixture with a treatment agent, and spray-drying the mixture, which is the subject of this application. SUMMARY OF THE INVENTION The present invention provides a process for preparing pigments characterized by improved fluidity, low dust production and good dispersibility, without the expensive and intense energy micronization step. In this processAt least one treatment agent is deposited in a pigment, preferably an inorganic pigment that has been ground, as an aqueous mixture. The treated mixture is then dehydrated by spraying for the performance of its final use without jet grinding or micronization. DESCRIPTION OF THE PREFERRED MODALITIES The pigments which may be subjected to the treatment process described hereinafter to provide the improved pigments of the present invention include any of the known or used opacifying or non-opacifying, white or colored particulate pigments (or mineral pigments). in the industries of surface coatings (for example painting) and plastics. For purposes of the present disclosure, the term "pigments" is widely used to define materials that are particulate by nature and non-volatile when used, and are typically more usually referred to as inhertes, fillers, extender pigments, reinforcing pigments and the like and are preferably inorganic pigments, representative but not limiting examples of the pigments which can be treated as described herein to provide the improved pigments of this invention, include white opacifying pigments, such as titanium dioxide, basic carbonate lead white, basic white lead sulfate, basic silicon lead white, zinc sulfate, zinc oxide, pigments composed of zinc sulfate, barium sulfate, antimony oxide and the like, white extension pigments such as calcium carbonate, calcium sulfate, porcelain clays and kaolin, mica, diatomite and colorear pigments such as iron oxide, lead oxide, cadmium sulfate, cadmium selenide, lead chromate, zinc chromate, nickel titanium, chromium oxide and the like. Of all the pigments useful in the production of the improved pigments of the present invention, the most preferred pigment is titanium dioxide. In general, the preferred titanium dioxide pigment for use in the process of this invention can be any of the anatase or rutile crystal structures or a combination thereof. The pigment can be produced by various known commercial processes which are familiar to those of experience in this matter but whose processes are not part of the present invention. Thus, the particular pigment can be produced either by the well-known sulfate process, or the well-known vapor phase oxidation process. The sulfate process typically involves the steps of leaching a titaniferous mineral with sulfuric acid to produce a solution of titanium sulfate, the hydrolysis of titanium sulfate to form a precipitate of titanium dioxide and the calcination of this precipitate in the presence of additives. suitable for revealing the desired crystalline structure in the final product of calcined titanium dioxide. In the vapor phase oxidation process, a titanium halide such as a titanium tetrachloride is oxidized in the vapor phase at elevated temperatures to produce what is commonly referred to as natural titanium dioxide. This natural pyrogenic titanium dioxide product is then recovered, subjected to grinding and claasification operations and treatment is followed to deposit various hydrous metal oxide coatings on the pigment, undergoing a final grinding step to provide a pigment from the pigment. desired particle size. Typically, the final grinding step comprises the use of fluid grinding techniques. These techniques involve transporting the pigment through a grinding apparatus such as the fluid energy mills described in U.S. Patent Nos. 2,032,827 and 2,219,011 using one or more gaseous streams produced by jetting a grinding fluid such as air. or current to effect the collision between the individual pigment particles and thus a reduction in the size of such particles. Various additive materials can be incorporated into the pigment during the energy grinding of a fluid either to improve the grinding of the pigment as described in US Pat. No. 3., 531,310 or to improve particular chemical, physical and optical properties of the resultant ground pigment as described in U.S. Patent No. 4,752,340. Representative examples of such additive materials include polyols, such as glycerol, trimethylolethane of pentaerythritol, trimethylolpropane and the like, fatty acids such as oleic acid, stearic acid and the like, trialkanolamines such as triethanolamine and the like and salts amines such as triisopropanolamine succinate of triethanolamine melonate and the like. In the preparation of certain pigments, particularly titanium dioxide, it is difficult to produce a product that is low in disintegration, free flowing, dense and easily dispersed in paints and plastic mixtures. As discussed above, the titanium dioxide pigments normally produced and used in the paint, plastics and paper industries are generally in the form of a finely divided powder.

These powders are usually jet milled or micronized as a final stage in their production. Such grinding contributes to the dispersibility and brightness, but it is a stage of intense energy and therefore costly. Such powders are inherently disintegrated and exhibit poor flow characteristics. Free flowing powders with low disintegration can be obtained by the prior art methods of spray drying, however, these powders exhibit poor pigment properties. It has been discovered that the pigments produced by the present inventive process exhibit good optical and scattering properties, as well as low-disintegration and free-flowing properties without the incorporation of the expensive stage of intensive energy micronization. The product resulting from the inventive process is of low disintegration, it flows freely, it is dense, both oleophilic, hydrophobic and hydrophilic and it is easily dispersible in paints and plastic formulations. The present process is particularly well suited for titanium dioxide pigments, but may be equally beneficial for other inorganic pigment oxides used in paints and plastics. The surface treatment agents used may include a wide range of substances generally coating either hydrophilic or hydrophobic ends or both or mixtures of hydrophilic and hydrophobic agents. The hydrophilic ends may contain, but not be limited to, carboxyl, phosphate, sulfate, alcohol or amino groups. The hydrophobic groups may contain, but not be limited to aliphatic groups, silane and siloxane groups. The function of the surface treatment agents is to avoid the dispersed particles coming from the cementation simultaneously during the dehydration. The agents can also promote flocculation in the liquid phase during processing to allow the product to be filtered and washed. The agents play a third role in the process by acting as a binding agent in the dry product, both to reduce the disintegration and allow the formation of small globules of metal, grains or spheres to promote the properties of free fluid. Although spray drying is the preferred dewatering method, other dewatering equipment can be used to obtain the free fluid product including, but not limited to, an agglomerator, fluid bed drier, band drier, spray drier with an atomizer rotary, spray drier with a nozzle atomizer or spray tower with a nozzle atomizer or a combination of the above dehydration techniques or other dehydration techniques that may be useful for drying titanium dioxide. The process of the present invention produces a low-disintegration, free-flowing pigment that has not undergone any micronization treatment comprising the steps of: providing a pigment material, providing a source of water, forming a fine pigment mixture and water, well dispersed, grinding the mixture, depositing a treatment agent in the mixed ground pigment, and drying the pigment material having a treatment agent deposited therein. Advantageously, the pigment material is an inorganic pigment material and preferably is titanium dioxide. Advantageously, the treatment agent is deposited in the pigment material in an amount from about 0.3 percent to about 3.0 percent by weight based on the weight of the pigment material. Preferably, the treatment agent is deposited in an amount of from about 0.5 percent to about 1.0 percent and more preferably in an amount of about 0.8 percent. Advantageously, the mixture contains from about 10 percent to about 70 weight percent of the pigment material. Preferably the mixture contains from about 30 percent to about 60 percent by weight of the pigment material and more preferably the mixture contains about 50 percent by weight of the pigment material. Although the grinding stage can be carried out by any of the known milling equipment used with pigments, the preferred equipment is a sand mill. The process of the present invention may include the step of coating the pigment during mixing with a metal oxide. Advantageously, the metal oxide is selected from the group consisting of I2O3, SiC >; 2, and ZrÜ2.

Preferably the process of coating the pigment with a metal oxide produces a coating of about 0.25 percent to about 1.5 percent metal oxide. The treatment agent is advantageously selected from the group consisting of anionic, cationic and nonionic surfactants. When the treating agent is an anionic surfactant advantageously the pH during the deposition step is from about 1.5 to about 7.5, preferably the pH is from about 2.5 to about 5.5, and more preferably the pH of the deposition step is about of 3.5. When the treatment agent is a cationic surfactant, the pH of the deposition step is advantageously from about 4.5 to about 11.5. In the case when the treatment agent is a nonionic surfactanate the pH of the deposition step is advantageously from about 1.5 to about 11.5. Advantageously, the mixing step is carried out at a temperature of from about 10 ° C to about 90 ° C, preferably from about 25 ° C to about 80 ° C, and more preferably at a temperature of about 60 ° C. Advantageously, the step of depositing the treatment agent in the mixed ground pigment is carried out in a time from about 5 minutes to about 60 minutes, preferably in a time from about 5 minutes to about 30 minutes, and more preferably the stage Deposition is carried out in a time of approximately 5 minutes. The treatment agent useful in the present process for providing pigments of improved properties includes those compounds having the formula, ROOCCHSO3MCH2COOR 'wherein R and R' are monovalent alkyl radicals containing from about 2 to about 20 carbon atoms, preferably about 4 to about 14 carbon atoms, and more preferably about 8 carbon atoms and wherein M is a monovalent metal cation, more preferably, sodium. The monovalent alkyl radicals R and R ', in this formula, can be either straight chain or branched chain alkyl radicals. R can, but not necessarily be equal to R '. Representative examples of such radicals include methyl, ethyl, n-propyl, isobutyl, n-pentyl, isopentyl, n-hexyl, octyl, tridecyl and the like radicals. Non-limiting examples are dialkyl sulfosuccinate treatment agents useful in the preparation of improved pigments of the present invention including dioctyl sodium sulfosuccinate, sodium diisobutyl sulfosuccinate, bis-tridecyl sodium sulfosuccinate, sodium dihexyl sulfosuccinate and the like. The amount of the treatment agent used to treat the pigments described above, and particularly the titanium dioxide pigment will be of an amount sufficient to provide a treated pigment, which as long as it is not subjected to any micronization treatment usually exhibits low properties. disintegration and free fluid equal to or greater than the pigment that has been subjected to a costly micronization treatment. In general, the amount of treatment agent employed will be in the range of from about 0.3 to about 3.0 weight percent based on the weight of the pigment, preferably an amount ranging from about 0.5 to about 1.0 weight percent, and more preferably about 0.8 weight percent. The resulting treated inorganic pigments can be used quickly and evenly in a wide variety of paint and plastic formulations. These include the well-known classes of plastics such as polyolefin resins, acrylic resins, polyester resins, polyamide resins, epoxy resins, phenolic resins, poly (vinylaromatic) resins, (polyvinylidene) resins, polycarbonate resins, polyurethane resins, and the similar. Representative but non-limiting examples of these various classes of thermoplastic resins include: polyolefin resins, such as polyethylene, polypropylene, and the like; acrylic resins such as poly (acrylic acid), poly (methacrylic acid), poly (methacrylate), poly (methyl methacrylate), and the like; polyester resins such as poly (ethylene terephthalate), poly (butylene terephthalate) and the like; polyamide resins such as nylon-6 and nylon-6,6 and the like; epoxy resins such as poly (epichlorohydrin / bisphenol A) and the like and esters thereof such as those prepared by the esterification of poly (epichlorohydrin / bisphenol A) with a fatty acid, resin acid, liquid resin acid or mixtures thereof, phenolic resins such as those derived from the reaction of formaldehyde with phenol, resorcinol, cresol, p-phenylphenol, and the like; poly (vinyl aromatic) resins such as polystyrene and copolymers thereof such as poly (styrene-acrylonitrile), poly (styrene-butadiene-acrylonitrile), and the like; poly (vinylhalide) resins, such as poly (vinylchloride), poly (vinylchloride / vinylidene chloride) and the like; polycarbonate resins such as those achieved either by the phosgenation of dihydroxy aliphatic or aromatic monomers such as ethylene glycol, propylene glycol, bisphenol A (ie, 4,4'-isopropylidene diphenol), and the like or by transesterification of the catalyzed base of bisphenol A with diphenyl carbonate to produce bisphenol A polycarbonate; and polyurethane resins obtained by the reaction of di- or polyfunctional hydroxy compounds such as glycols or polyesters and hydroxyl terminated polyethers with di- or polyfunctional diisocyanates.

The amounts of the treated pigments of this invention that can be added directly to the plastics described above, can vary widely depending on the intended end use for those resins. Thus, sometimes thin films will require very high levels of pigment although coarse paints may only require a very small percentage. Accordingly, the amount of the treated pigment employed can vary from as small as about 1 weight percent to as much as about 80 weight percent based on the weight of the thermoplastic resin. In yet a further embodiment of the present invention, the treated inorganic pigment of the present invention has exhibited particular utility in the preparation of thermoplastic concentrates. In general, these thermoplastic concentrates will comprise a continuous phase which constitutes a thermoplastic resin and a dispersed phase constituting the treated inorganic pigments of this invention. The continuous phase may comprise any of the thermoplastic resins described above, including polyolefin resins, acrylic resins, polyester resins, polyamide resins, epoxy resins, phenolic resins, poly (vinylaromatic) resins, poly (vinylhalide) resins, Polycarbonate resins, polyurethane resins and the like.

In preparing the thermoplastic concentrates useful with the present invention, the amount of pigment incorporated in the continuous phase of the thermoplastic resin can vary widely. In general, this amount will vary depending on the level of pigmentation desired or required in the final product or final finish that employs these thermoplastic concentrates as pigment vehicles, and the effectiveness of the processing equipment used to reduce, dilute or dissolve the thermoplastic concentrates in the thermoplastic resins used to produce the final product or final. In general, the thermoplastic concentrates can contain proportions by weight of the treated pigments for the thermoplastic resin in which they are dispersed ranging from about 0.5: 1 to about 5: 1. Within such range, the treated pigments of the present invention can be easily and uniformly dispersed or distributed through the thermoplastic resin employed as the continuous phase of the thermoplastic concentrate produced. The invention is further described and illustrated by the following examples. These examples represent specific embodiments of the invention and are not construed as limiting thereof.

Example 1 A mixture of TiC sand mill discharge > 2 with the classification of 81 percent that happens to through a 0.49μ sieve and approximately 42 percent solids was dehydrated by spraying in a nozzle spray directed upwards. The drying gas is fed countercurrent to the spray direction. The gas inlet temperature was 400 ° C and the gas outlet temperature was 165 ° C. The pH of the mixture was about 10 and it was at room temperature. A SF1.3 type nozzle with a feed pressure of 365 psig was used to spray the mixture in the desiccator. The drying air velocity was 3.150 lb / hr. The moisture content of the dehydrated product by spray was 0.19 percent. The spray dried product had a particle size distribution of 10 percent, 50 percent and 90 percent passing through 45μ, 100μ, and 154μ sieves, respectively. The contents of TOC, Na2S04, NaCl, Cl-free, and Al203 were 0.03, 0.05. 0.25, 0.15, and 0.76 percent respectively. The pH and specific resistance were 9.7 and 1.375 ohm / cm. The emptying and derivative densities were 1.01 and 1.06 g / cc. The spray dried powder was free flowing and low disintegration.

The powder dehydrated by sprinkling. it was then mixed in low density polyurethane at a load of 75 weight percent for the equilibrium torque values in a Brabender torque rheometer. The equilibrium torque was 3, 320 meter-grams. The temperature of the plastic stocks in the final test was 176 ° C. The total energy for the equilibrium torque was 15,493 km-grams. This product dehydrated by the prior art process produces a very high equilibrium torque without micronization. Micronization of the product with an organic milling aid of TME or TMP as at about a 1.5 steam: pigment reduced the 75 percent loading in LDPE equilibrium torque to about 1,400-1,500 meter-grams. Typically, a lower value of torque equilibrium indicates better plastic processing performance. Therefore, the previous technique requires additional processing that represents the higher cost of the process since in micronization it is necessary to achieve an acceptable equilibrium torque value. Example 2 232 pounds of the sand mill discharge mix of IO2 was treated with sodium dictyl sulfosuccinate in a 60 gallon stirred reaction tank. The discharge of the sand milling of TÍO2 had a classification greater than 95 percent passing through a 0.5μ sieve.

The density of the mixture was 36.8 percent solids and the initial pH was 9.3. The mixture was heated to 60 ° C using steam and stirred sufficiently to produce a slight whirlpool. 350 ml of concentrated HCl acid was added for several minutes to lower the pH of the mixture to 3.4. 1.87 pounds of dioctyl sodium sulfosuccinate was then added for several minutes. The viscosity of the mixture increased almost immediately due to flocculation of TiC > 2 and the stirring was increased at the same time to produce a slight whirlpool. The dioctyl sodium sulfosuccinate was reacted for 5 minutes and the mixture was then pumped to a 55 gallon drum and cooled. The iC > 2 sedimented from 36.8 percent solids to approximately 49 percent solids in 15 minutes. The mixture was adjusted to 42.7 percent solids and dehydrated by spray through an up-directed nozzle atomizer. The desiccator was fed countercurrent to the spray direction. The pH of the mixture and the temperature were 4.0 and at room temperature. The inlet temperature of the desiccant gas was 450 ° C and the outlet temperature of the gas was 160 ° C. A SGI.4 type nozzle with a feed pressure of 500 psig was used to spray the mixture into the desiccator. The speed of the drying air was 3.061 lb / hr. The moisture content of the dehydrated product by spray was 0.28 percent. The spray dried product had a particle size distribution of 10 percent, 50 percent and 90 percent passing through the 38μ, 98μ and 180μ sieves respectively. The contents of dioctyl sodium sulfosuccinate, TOC, Na2S04, NaCl, Cl-free and A1 03, were 0. 81, 0.46, 0.06, 0.16, 0.16 and 0.98 percent respectively. The pH and specific resistance were 5.3 and 1.936 ohm / c. The emptying and derivative densities were 0.91 and 1.00 g / cc. The spray dried powder was free flowing and low disintegration. The spray-dried powder was then mixed in low density polyethylene at a load of 75 weight percent to give equilibrium torque values of approximately 1,340 meter-grams. The temperature of the plastic stocks at the end of the test was 123 ° C. The total energy for the equilibrium torque was 4,679 km-grams. The lower temperature of the stock, the equilibrium torque and the total energy indicate that the product processed well in polyethylene. In addition, the micronization of the product is not necessary to achieve an acceptable equilibrium torque. Therefore, the cost of the process is lower because micronization is not necessary and packing and storage costs are lower because the high density of emptying of the dehydrated product by spray is retained. Example 3 241 pounds of TiC sand mill discharge mix > 2 were treated with dioctyl sodium sulfosuccinate in a stirred tank of 60 gallons. The discharge of the sand mill from iC > 2 had a classification greater than 95 percent passing through a 0.5μ sieve. The density of the mixture was 36.8 percent solids and the initial pH was 9.3. The mixture was heated to 60 ° C using steam and stirred sufficiently to produce a slight whirlpool. 6.22 pounds of 1.46 g / cc of sodium aluminate was added to the mixture for 5 minutes to increase the pH to 11.2. The sodium aluminate was allowed to react for 15 minutes before 1.975 ml of concentrated HCl acid was added for several minutes. After the pH decreased to 3.6, the 2.94 pounds of dioctyl sodium sulfosuccinate were added for several minutes. The viscosity of the mixture increased almost immediately due to the flocculation of the TIO2 and the stirring was increased at the same time to produce a slight swirl The dioctyl sodium sulfosuccinate was reacted for 5 minutes and the mixture was then pumped to a 55 gallon drum and cooled. The mixture was adjusted to 33.9 percent solids and dehydrated by spray through an upwardly directed nozzle atomizer. The drying gas was fed countercurrent to the spray direction. The pH of the mixture and the temperature were 4.0 and at room temperature. The inlet temperature of the drying gas was 430 ° C and the outlet temperature of the gas was 163 ° C. A SGI.2 type nozzle with a feed pressure of 500 psig was used to spray the mixture into the desiccator. The speed of the drying air was 2, 973 lb / hr. The moisture content of the dehydrated product by spray was 0.36 percent. The spray dried product had a particle size distribution of 10 percent, 50 percent and 90 percent passing through the sieves of 45, 99 and 147μ respectively. The contents of dioctyl sodium sulfosuccinate, TOC, Na2S04, NaCl, Cl-free and A1203, were 1.18, 0.67, 0.03, 1.16, 0.89 and 1.51 percent respectively. The pH and specific resistance were 5.1 and 408 oh / cm. The emptying and derivative densities were 0.83 and 0.89 g / cc. The spray dried powder was free flowing and low disintegration. The spray-dried powder was mixed in low density polyethylene at a load of 75 weight percent to give equilibrium torque values of approximately 1440 meter-grams. The temperature of the plastic stocks at the end of the test was 130 ° C. The total energy for the equilibrium torque was 5,491 km-grams. The micronization of the product was not necessary to achieve a satisfactory equilibrium torque. An equilibrium torque of 1,440 meter-grams indicates that the iC >2 treated had excellent processability in plastics, along with the advantage of increasing the ductility of the coating of alumina Therefore the cost of the process is lower because it is not necessary micronization and packaging and storage costs are lower because the high density of emptying the dehydrated product by spray is retained.

Claims (34)

1. NOVELTY OF THE INVENTION Having described the present invention is considered as a novelty and therefore the content of the following claims is claimed as property. A process for preparing a freely flowing low disintegration pigment which has not been subjected to any micronization treatment characterized in that it comprises the steps of: a. provide a pigment material; b. provide a source of water; c. form a fine mixture of pigment and well dispersed water; d. grind the mixture; and. depositing a treatment agent on the mixed ground pigment; and f. drying the pigment material having a treatment agent deposited therein.
2. 2. The process according to claim 1, characterized in that said treatment agent has the formula ROOCCHSO3MCH2COOR 'wherein R and R' are monovalent alkyl radicals having from about 2 to about 20 carbon atoms and M is a monovalent metal cation.
3. 3. The process according to claim 2, characterized in that R and R 'are monovalent alkyl radicals having from about 4 to about 14 carbon atoms each.
4. The process according to claim 3, characterized in that R and R 'are monovalent alkyl radicals having approximately 8 carbon atoms each and M is sodium.
5. 5. The process according to claim 2, characterized in that said treatment agent is sodium dioctyl sulfosuccinate.
6. The process according to claim 1, characterized in that said pigment material is an inorganic pigment material.
7. The process according to claim 6, characterized in that said pigment material is titanium dioxide.
8. The process according to claim 1, characterized in that said treatment agent is deposited on said pigment material in step (e) in an amount in the range of from about 0.3 percent to about 3.0 percent by weight based on weight of said pigment material.
9. The process according to claim 8, characterized in that said treatment agent is deposited on said pigment material in step (e) in an amount of from about 0.5 percent to about 1.0 percent by weight based on the weight of said pigment material.
10. The process according to claim 9, characterized in that said treatment agent is deposited on said pigment material in step (e) in the amount of about 0.80 weight percent based on the weight of said pigment material.
11. The process according to claim 1, characterized in that the mixture formed in step (c) contains from about 10 percent to about 70 percent by weight of the pigment material.
12. The process according to claim 11, characterized in that the mixture formed in step (c) contains from about 30 percent to about 60 weight percent of the pigment material.
13. The process according to claim 12, characterized in that the mixture formed in step (c) contains about 50 weight percent of the pigment material.
14. The process according to claim 1, characterized in that the grinding stage (d) is carried out in a sand mill.
15. 15. The process according to claim 1, characterized in that it includes the step of coating the pigment in the mixture formed in step (c) with a metal oxide.
16. 16. The process according to claim 15, characterized in that the metal oxide is selected from the group consisting of AI2O3, SiO2 and ZrC ^.
17. The process according to claim 15, characterized in that the metal oxide coating is present in an amount from about 0.25 percent to about 1.5 percent by weight.
18. 18. The process according to claim 1, characterized in that the treatment agent is an anionic surfactant.
19. 19. The process according to claim 18, characterized in that the pH of the deposition step (e) is from about 1.5 to about 7.5.
20. The process according to claim 19, characterized in that the pH of the deposition step (e) is from about 2.5 to about 5.5.
21. The process according to claim 20, characterized in that the pH of the deposition step (e) is approximately 3.5.
22. 22. The process according to claim 1, characterized in that the treatment agent is a cationic surfactant.
23. 23. The process according to claim 22, characterized in that the pH of the deposition step (e) is from about 4.5 to about 11.5.
24. 24. The process according to claim 1, characterized in that the treatment agent is a nonionic surfactant.
25. 25. The process according to claim 24, characterized in that the pH of the deposition step (e) is from about 1.5 to about 11.5.
26. 26. The process according to claim 1, characterized in that step (c) is carried out at a temperature of from about 10 ° C to about 90 ° C.
27. 27. The process according to claim 26, characterized in that step (c) is carried out at a temperature of from about 25 ° C to about 80 ° C.
28. 28. The process according to claim 27, characterized in that step (c) is carried out at a temperature of about 60 ° C.
29. 29. The process according to claim 15, characterized in that the step of deposition (e) is carried out for a time from about 5 minutes to about 60 minutes.
30. 30. The process according to claim 29, characterized in that the step of deposition (e) is carried out for a time from about 5 minutes to about 30 minutes.
31. 31. The process according to claim 30, characterized in that the deposition step (e) is carried out for a time of about 5 minutes.
32. 32. A free-flowing, non-micronized low-disintegration pigment produced by the process of claim 1.
33. 33. A paint formulation containing the pigment of claim 32.
34. 34. A plastic formulation containing the pigment of claim 32