Inorganic pigments treated with PHMS / PDMS copolymers

Abstract

The present invention provides a method for preparing a treated inorganic pigment. The method includes providing a plurality of inorganic pigment particles and depositing an organic treatment agent on a surface of the pigment particles to form at least one coating of the organic treatment agent thereon. The organic treatment agent is selected from the group consisting of: a copolymer of polyhydromethylsiloxane (PHMS) and polydimethylsiloxane (PDMS) ("PHMS / PDMS copolymer"), and a combination of PHMS / PDMS copolymer and net PHMS polymer. The invention also provides a treated inorganic pigment.

Description

BACKGROUND

[0001] Inorganic pigments are commonly added to polymers, coatings (e.g., waterborne paints), paper, and other types of products to act as fillers, extenders, colorants, and / or opacifiers therein. Examples of white opacifying inorganic pigments include titanium dioxide, basic carbonate white lead, zinc sulfide, zinc oxide, antimony oxide, calcium carbonate, china and kaolin clays, iron oxide, and chromium oxide.

[0002] Titanium dioxide (Ti02) has become one of the most commonly used white pigments worldwide due to its high refractive index, strong opacifying power, and other factors. Purified titanium dioxide (Ti02) is produced from ore (e.g., ilmenite and rutile) by either the sulfate process or the chloride process. Each process can produce pigments of the rutile crystal form. The sulfate process can also produce pigments of the anatase crystal form, which can be softer and particularly suitable for certain applications.

[0003] One or more inorganic and / or organic materials are typically deposited on the surface of the produced inorganic pigment particles to form one or more coatings thereon. The coatings of inorganic and / or organic materials serve to enhance certain properties and characteristics of the pigments, such as the opacity, light stability, durability, wettability, and / or dispersibility of the pigments.

[0004] Examples of inorganic materials for deposition on the surface of inorganic pigment particles including titanium dioxide pigment particles for various purposes include aqueous inorganic metal oxides, such as silica, alumina, and zirconia. Examples of organic materials for deposition on the surface of inorganic pigment particles including titanium dioxide pigment particles for various purposes include organic polyols, silanes, polysiloxanes, salts of saturated fatty acids, salts of unsaturated fatty acids, and phosphonic acids. The particular inorganic and / or organic compounds used depend on the properties and characteristics desired for the pigments and the intended end-use applications.

[0005] For example, polymethylhydrogen siloxane (PMHS) is a hydrophobic organic polymer that has been used to surface treat inorganic pigments, such as titanium dioxide pigments used in certain applications. PMHS has the following structure: For example, PMHS has been sprayed on finished titanium dioxide pigments to improve the processability of the pigments as well as the performance of the pigments in certain end-use applications.

[0006] Polycarbonates are a class of thermoplastic polymers that are widely used as engineering plastics in various industries, including the automotive, electronics, and medical device industries. Polycarbonate-based plastics are strong, tough materials. Titanium dioxide pigments are often added to polycarbonate compositions to impart whiteness, brightness, and opacity to the resulting polycarbonate articles. Titanium dioxide pigments also minimize brittleness, discoloration, and cracking of polycarbonate articles.

[0007] Inorganic pigments such as titanium dioxide pigments can cause problems when used in polycarbonate and other types of polymer compositions. For example, hydroxyl groups associated with certain surface coatings can interact with the polymer during processing of the polymer composition and adversely affect the stability of the polymer.

[0008] An example of a surface coating for inorganic pigments such as titanium dioxide that does not adversely interact with polycarbonate or other polymers in a polymer composition is PHMS. However, it can be difficult to produce a finished inorganic pigment that contains PHMS in an amount sufficient to achieve the desired processing effects. Unfortunately, after PHMS is deposited onto the surface of the pigment, it can be subject to substantial loss during subsequent pigment finishing steps. For example, 50 to 60 weight percent of PHMS coated onto titanium dioxide pigments can be lost in the presence of high processing temperatures and / or steam that are typically encountered in pigment finishing processes. Hydrogen gas in PHMS tends to evolve, which not only creates an explosive environment, but also causes degradation of the PHMS coating on the pigment particles. Although PHMS is relatively stable at ambient temperatures, the active hydrogen in PHMS is highly reactive at high temperatures.

[0009] There is a need for an organic treatment agent for treating inorganic pigments such as titanium dioxide pigments that does not adversely affect the stability of polycarbonate and other types of polymer compositions and is resistant to high temperatures associated with pigment finishing processes. SUMMARY

[0010] In one aspect, provided herein is a method for preparing a treated inorganic pigment. The method includes providing a plurality of inorganic pigment particles and depositing an organic treatment agent on the surface of the pigment particles to form at least one coating of the organic treatment agent thereon. The organic treatment agent is selected from the group consisting of: a PHMS / PDMS copolymer, and a combination of a PHMS / PDMS copolymer and a neat PHMS polymer.

[0011] In another aspect, provided herein is a treated inorganic pigment. The pigment comprises a plurality of inorganic pigment particles, and an organic treatment agent deposited on the surface of the pigment particles to form at least one coating of the organic treatment agent thereon. The organic treatment agent is selected from the group consisting of: a PHMS / PDMS copolymer, and a combination of a PHMS / PDMS copolymer and a neat PHMS polymer. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figures 1 to 4 is a chart corresponding to Example 1. DETAILED DESCRIPTION The present disclosure can be more easily understood and further advantages and benefits can be obtained, when the following detailed description including the drawings is considered in conjunction with the foregoing general description. Numerous specific details are set forth in order to provide a thorough understanding of various aspects of the present disclosure. However, it will be apparent to one skilled in the art that the present disclosure can be practiced without incorporating these specific details. The particularity of the detailed description is not intended to limit the scope of the claims.

[0014] When a range is disclosed herein, the range is inclusive of the integers recited as the lower and upper limits of the range. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, can contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0015] In one aspect, disclosed herein is a method for making a treated inorganic pigment. In another aspect, disclosed herein is a treated inorganic pigment.

[0016] The method disclosed herein comprises providing a plurality of inorganic pigment particles, and depositing an organic treatment agent on the surface of the pigment particles to form at least one coating of the organic treatment agent thereon. The organic treatment agent is selected from the group consisting of: a PHMS / PDMS copolymer, and a combination of a PHMS / PDMS copolymer and a neat PHMS polymer. As used herein and in the appended claims, "PHMS / PDMS copolymer" means a copolymer of polyhydro methylsiloxane (PHMS) and polydimethylsiloxane (PDMS). "Neat PHMS polymer" means a PHMS polymer, as opposed to a copolymer comprising PHMS. When a combination of a PHMS / PDMS copolymer and a neat PHMS polymer is used, separate coatings of the PHMS / PDMS copolymer and the neat PHMS polymer are formed. The PHMS / PDMS copolymer and the neat PHMS polymer do not react.

[0017] The PHMS / PDMS copolymer and the neat PHMS polymer are both hydrophobic organic polymers. As shown in the examples set forth below, the PHMS / PDMS copolymer, both by itself and in combination with PHMS, is more stable at high temperatures than PHMS alone or even a simple blend of PHMS and PDMS. This minimizes hydrogen evolution and the resulting loss of the polysiloxane copolymer in subsequent pigment finishing steps. In addition, by using the PHMS / PDMS copolymer, the bulk density of the treated inorganic pigment is increased relative to the use of PHMS alone.

[0018] As used herein and in the appended claims, inorganic pigment refers to a particulate inorganic pigment, which is an inorganic pigment in the form of a plurality of pigment particles. For example, the inorganic pigment can be in the form of a dry powder or dry particles. As used herein and in the appended claims, unless otherwise specified, "deposited on," "formed on," and "precipitated on" the surface of an inorganic pigment particle (or another component, such as another coating layer) means deposited, formed, or precipitated, as the case can be, directly or indirectly on the surface of the inorganic pigment particle (or other component). For example, unless otherwise specified, a treatment agent deposited on the surface of an inorganic pigment particle means that the treatment agent is formed directly on the inorganic pigment particle and / or on one or more coating layers formed directly or indirectly on the inorganic pigment particle.

[0019] For example, the inorganic pigment particles can be provided by preparing the inorganic pigment as part of the methods disclosed herein. Alternatively, the inorganic pigment particles can be provided from a source of inorganic pigment that has already been prepared. For example, one or more bulk containers (e.g., bags) of pre-existing inorganic pigment can be used as the source of inorganic pigment.

[0020] Examples of inorganic pigments that can be used herein include titanium dioxide, zinc oxide, complex pigments of zinc sulfide and barium sulfate, calcium carbonate, china clay and kaolin, mica, diatomaceous earth, and talc.

[0021] For example, the treated inorganic pigment can be a treated titanium dioxide pigment, and the inorganic pigment particles used herein can be titanium dioxide pigment particles. The manner in which the titanium dioxide particles are prepared, whether as part of the methods disclosed herein or otherwise, is not important. For example, the titanium dioxide particles can be titanium dioxide particles prepared by the sulfate process. For example, the titanium dioxide particles can be titanium dioxide particles prepared by the chloride process. The particles can have a rutile crystal structure, an anatase crystal structure, or a combination thereof. For example, the titanium dioxide particles can have a rutile crystal structure. For example, the titanium dioxide particles can have an anatase crystal structure.

[0022] In the sulfate process for preparing titanium dioxide, a titanium slag ore, typically ilmenite, is dissolved in sulfuric acid to form titanyl sulfate. The titanyl sulfate is then hydrolyzed to form hydrous titanium dioxide. The hydrous titanium dioxide is heated in a calciner to grow the titanium dioxide crystals to pigmentary dimensions.

[0023] In the chloride process for preparing titanium dioxide, dry titanium dioxide ore is fed into a chlorinator along with coke and chlorine gas 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 titanium dioxide particles having a desired particle size. Aluminum chloride is typically added to the titanium halide in the oxidation reactor to incorporate alumina into the crystal lattice of the titanium dioxide particles, thereby promoting the formation of rutile and controlling the particle size. The titanium dioxide and gaseous reaction products are then cooled and the titanium dioxide particles are recovered.

[0024] Titanium dioxide particles can contain alumina as part of their crystal lattice structure. For example, aluminum chloride can be added to the reactants as a rutilization aid during the gas phase oxidation step of the chloride process. When present during the oxidation reaction, the aluminum chloride imparts alumina into the crystal lattice structure of the pigment.

[0025] As used herein and in the appended claims, the term "copolymer" refers to a polymer derived from more than one type of monomeric species. In a copolymerization process, different types of monomeric subunits are linked to form a polymer chain. In the case of the PHMS / PDMS copolymers used herein, PHMS and PDMS are monomeric subunits and are linked together to form a polymer chain.

[0026] For example, the PHMS / PDMS copolymer, whether used alone or in combination with neat PHMS polymer, contains in the range of about 20 wt% to about 80 wt% PHMS, and in the range of about 80 wt% to about 20 wt% PDMS, the weight percentages being based on the total weight of the copolymer. For example, the PHMS / PDMS copolymer contains in the range of about 30 wt% to about 60 wt% PHMS, and in the range of about 70 wt% to about 40 wt% PDMS, the weight percentages being based on the total weight of the copolymer. For example, in one embodiment, the PHMS / PDMS copolymer contains about 60 wt% PHMS and about 40 wt% PDMS, the weight percentages being based on the total weight of the copolymer.

[0027] The PHMS / PDMS copolymer can be a random copolymer, or a block copolymer composed of PHMS and PDMS units. The PHMS / PDMS copolymer can be linear or branched, and can have a total molecular weight in the range of about 2000 to about 20000.

[0028] In one embodiment, the organic treatment agent is a PHMS / PDMS copolymer. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount of at least about 0.5 wt% based on the weight of the inorganic pigment particles. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount in the range of about 0.5 wt% to about 5 wt% based on the weight of the inorganic pigment particles. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount in the range of about 1.5 wt% to about 4 wt% based on the weight of the inorganic pigment particles. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount in the range of about 1.5 wt% to about 3 wt% based on the weight of the inorganic pigment particles. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount in the range of about 2 wt% to about 3 wt% based on the weight of the inorganic pigment particles. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount of about 2.5 wt% based on the weight of the inorganic pigment particles. As used herein and in the appended claims, "based on the weight of the inorganic pigment particles" means based on the total weight of the original inorganic pigment particles and all inorganic and organic materials deposited thereon.

[0029] For example, as shown in Example 4 below, when the organic treatment agent is a PHMS / PDMS copolymer, and the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount in the range of about 1.5 wt% to about 3 wt% based on the weight of the inorganic pigment particles, the packed bulk density of the treated inorganic pigments is in the range of about 0.55 g / cc to about 0.63 g / cc. The bulk density is significantly increased compared to using PHMS alone as the organic treatment agent.

[0030] As used herein and in the appended claims, the "filled bulk density" of a treated inorganic pigment refers to the bulk density (mass / volume) of the pigment as measured using a Hosokawa Micron Powder Tester PT-E after pouring the pigment into a container (e.g., a 100 cc beaker) by filling the container with the pigment until the pigment overflows, scraping off the excess pigment from the top of the container, and tapping the pigment in the container 60 cycles within 180 seconds to expel entrained air (according to the Hosakawa method). The "poured bulk density" of a treated inorganic pigment refers to the bulk density (mass / volume) of the pigment as measured using a Hosokawa Micron Powder Tester PT-E after pouring the pigment into a container (e.g., a 100 cc beaker) by filling the container with the pigment until the pigment overflows, and scraping off the excess pigment from the top of the container, thereby forming a relatively loose structure of the pigment in the container (according to the Hosakawa method).

[0031] In another embodiment, the organic treatment agent is a combination of a PHMS / PDMS copolymer and neat PHMS polymer. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.5 wt% to about 5 wt%, and the neat PHMS polymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.2 wt% to about 4 wt%, the weight percentages being based on the weight of the inorganic pigment particles. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 1.5 wt% to about 4 wt%, and the neat PHMS polymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.5 wt% to about 3 wt%, the weight percentages being based on the weight of the inorganic pigment particles. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 2 wt% to about 3 wt%, and the neat PHMS polymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.2 wt% to about 2 wt%, the weight percentages being based on the weight of the inorganic pigment particles.

[0032] The organic treatment agent can be deposited on the surface of the inorganic pigment particles by any technique known in the art for surface treating pigments. For example, the organic treatment agent can be deposited on the surface of the pigment particles in a fluid energy mill. When the inorganic pigment is in dry form, the organic treatment agent can be mixed with or sprayed onto the inorganic pigment. The organic treatment agent can also be added to a slurry containing the inorganic pigment and dried therewith.

[0033] For example, in one embodiment, the method further comprises: forming a slurry of the inorganic pigment particles prior to depositing the organic treatment agent on the surface of the inorganic pigment particles; and filtering the inorganic pigment particles to form a filter cake comprising the inorganic pigment particles. The organic treatment agent is then deposited on the surface of the inorganic pigment particles by mixing the organic treatment agent with the filter cake to form a coating of the organic treatment agent thereon. For example, the pigment particles are washed and recovered by the filtering step. The recovered pigment particles can then be dried as part of a pigment finishing process.

[0034] For example, in one embodiment, the method further comprises: depositing an inorganic treatment agent on the surface of the inorganic pigment particles to form a coating of the inorganic treatment agent thereon prior to depositing the organic treatment agent on the surface of the inorganic pigment particles. For example, the organic treatment agent is deposited on top of the coating of the inorganic treatment agent to form a coating thereon.

[0035] For example, a first inorganic treatment agent can be deposited on the surface of the inorganic pigment particles to form a coating of the first inorganic treatment agent thereon, and a second inorganic treatment agent can be deposited on the coating of the first inorganic treatment agent to form a coating of the second organic treatment agent thereon. A third inorganic treatment agent can then 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, when more than one inorganic treatment agent is deposited on the surface of the inorganic pigment particles to form more than one coating of the inorganic treatment agent thereon, the organic treatment agent is deposited on top of all of the coatings of the inorganic treatment agent. For example, if a first and second inorganic treatment agent is deposited on the pigment, the organic treatment agent is deposited on top of the coating of the second inorganic treatment agent. For example, depositing the organic treatment agent on top of the coating of the inorganic treatment agent (and any other organic material deposited on the surface of the titanium dioxide particles) can facilitate and improve the compatibility of the inorganic pigment with the inorganic treatment agent when used in conjunction with a polymeric resin system.

[0037] For example, the inorganic treatment agent can be deposited on the surface of the inorganic pigment particles to form one or more coatings of the inorganic treatment agent thereon by forming an aqueous slurry of the inorganic pigment particles, and precipitating the inorganic treatment agent onto the surface of the inorganic pigment particles in the slurry. Techniques are known in the art for precipitating one or more inorganic or organic treatment agents onto the surface of inorganic pigment particles, such as titanium dioxide pigment particles, in a slurry containing the inorganic pigment particles by successively adding the treatment agents to the slurry, and adjusting the pH of the slurry as necessary so that the treatment agents precipitate onto the surface of the inorganic pigment particles, either directly or indirectly. The inorganic and organic treatment agents are precipitated in situ onto the inorganic pigment particles in the aqueous slurry.

[0038] For example, to deposit a metal oxide inorganic treatment agent on the surface of a plurality of inorganic pigment particles to form a coating thereon, the metal oxide inorganic treatment agent can be gradually added to the aqueous slurry as an aqueous metal oxide salt solution. The pH and temperature of the slurry can be adjusted and maintained at a level such that precipitation of the particular metal oxide inorganic treatment agent occurs. To control the pH of the slurry, a strong inorganic acid such as hydrochloric acid, nitric acid, sulfuric acid, and salts thereof can be used. Each individual inorganic treatment agent that precipitates onto the surface of the inorganic pigment particles in the slurry forms a separate coating on the surface of the inorganic pigment particles, either directly or indirectly.

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

[0040] The inorganic treatment agent can be used to impart one or more properties and / or characteristics to the inorganic pigment particles, or to enhance the properties and / or characteristics, to make the particles more suitable for end use applications, i.e., in the base composition (e.g., polymer composition) to which the inorganic pigment is to be added, and the products (e.g., plastic articles) made therefrom. For example, silica and / or alumina treatment agents can be used to help improve the wetting and dispersion properties of titania pigments, as well as the opacity, light stability, and durability of the pigments.

[0041] For example, the inorganic treatment agent can be deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.5 wt% to about 15 wt%, based on the weight of the inorganic pigment particles. For example, the inorganic treatment agent can be deposited on the surface of the inorganic pigment particles in an amount ranging from about 1 wt% to about 10 wt%, based on the weight of the titania particles.

[0042] For example, in one embodiment, the method disclosed herein is a method for making a treated titania pigment, and comprises the following steps: (a) providing a plurality of titania pigment particles; (b) after step (a), forming an aqueous slurry of the titania pigment particles; (c) after step (b), reducing the particle size of the titania particles in the aqueous slurry to a desired particle size; (d) after step (c), depositing an inorganic treatment agent (or sequentially depositing more than one inorganic treatment agent) on the surface of the titania pigment particles in the aqueous slurry to form a coating of the inorganic treatment agent thereon (or separate coatings of each inorganic treatment agent thereon); (e) after step (d), filtering the surface-treated titanium dioxide pigment particles to form a filter cake comprising the surface-treated titanium dioxide pigment particles; (f) after step (e), mixing an organic treatment agent with the filter cake to deposit the organic treatment agent on the coating of inorganic treatment agent; (g) after step (f), drying the filter cake; (h) after step (g), reducing the particle size of the treated titanium dioxide particles forming the filter cake to a desired particle size distribution; and (i) after step (h), encapsulating the treated titanium dioxide pigment.

[0043] As discussed above, the titanium dioxide pigment can be prepared by being part of the method disclosed herein, while the titanium dioxide pigment particles are provided in step (a). Alternatively, the titanium dioxide pigment particles can be provided in step (a) from a source of titanium dioxide that has been prepared.

[0044] The slurry of titanium dioxide pigment particles can be formed in step (b) by mixing the titanium dioxide particles into an aqueous medium. If necessary or desired, a dispersant such as a polyphosphate can be added to the aqueous slurry to facilitate the distribution of the titanium dioxide pigment particles therein. For example, the titanium dioxide pigment particles are added to the aqueous slurry in an amount ranging from about 5 wt% to about 65 wt%, based on the total weight of the slurry. By way of further example, the titanium dioxide particles are added to the slurry in an amount ranging from about 15 wt% to about 45 wt%, based on the total weight of the slurry. For example, the titanium dioxide particles are added to the aqueous slurry in an amount ranging from about 25 wt% to about 40 wt%, based on the total weight of the slurry.

[0045] The particle size of the titanium dioxide pigment particles can be reduced in step (c) to a desired particle size by wet milling the pigment particles in the aqueous slurry. For example, the pigment particles in the aqueous slurry can be wet milled such that at least about 50% of the pigment particles in the slurry have a particle size of less than 0.5 microns. Various wet milling techniques known in the art can be used to perform the wet milling step, including cage milling, bead milling, jet milling, and sand milling.

[0046] According to step (d), the inorganic treatment agent can be deposited onto the surface of the titanium dioxide pigment particles in the slurry by precipitating the inorganic treatment agent onto the surface of the titanium dioxide pigment particles as discussed above to form one or more coatings of inorganic treatment agent thereon.

[0047] According to step (e), the treated titanium dioxide pigment particles can be filtered by methods known to those skilled in the art to form a filter cake comprising the surface treated titanium dioxide pigment particles. For example, the treated titanium dioxide pigment particles can be recovered by filtration to form a filter cake of the particles and washed using conventional vacuum and / or pressure filtration systems. Wet treatment deposition of the inorganic treating agent onto the titanium dioxide pigment particles, e.g., onto the wet milled titanium dioxide particles, facilitates the ability of the pigment to be recovered and washed using conventional vacuum and / or pressure filtration systems.

[0048] If the organic treating agent is a combination of PHMS / PDMS copolymer and neat PHMS polymer, the two organic polymers can be mixed with the filter cake separately or as a mixture according to step (f). The order of addition of the organic polymers is not important.

[0049] According to step (g), the filter cake, which has now been treated with one or more inorganic treating agents and an organic treating agent, can be dried by vacuum drying, spin flash drying, spray drying, oven drying, or other techniques known to those skilled in the art to produce a dry inorganic pigment powder. In one embodiment, according to step (g), the filter cake is dried by spray drying the particles.

[0050] In step (h), the particle size of the treated titanium dioxide pigment particles forming the dried filter cake can be reduced to a desired particle size distribution by, for example, dry milling the pigment particles. For example, fluid energy milling can be used to dry mill the pigment particles. Alternatively, the dried pigment particles can be reduced to a desired particle size distribution by steam micronization techniques. As shown in the examples below, the PHMS / PDMS copolymer organic treating agent is generally resistant to the high temperatures and steam associated with steam micronization techniques.

[0051] The treated titanium dioxide pigment can then be encapsulated by any encapsulation technique known in the art. For example, the dried and milled treated titanium dioxide pigment can be placed in a bag and shipped therein.

[0052] The treated inorganic pigment provided herein comprises a plurality of inorganic pigment particles, and an organic treating agent deposited on the surface of the inorganic pigment particles and forming a coating of the organic treating agent thereon. The organic treating agent is selected from the group consisting of: PHMS / PDMS copolymer, and a combination of PHMS / PDMS copolymer and neat PHMS polymer. The PHMS / PDMS copolymer is the PHMS / PDMS copolymer described above in connection with the methods disclosed herein.

[0053] For example, the treated inorganic pigment is a treated titanium dioxide pigment, and the inorganic pigment particles are titanium dioxide particles.

[0054] For example, the titanium dioxide particles can be titanium dioxide particles prepared by the sulfate process. For example, the titanium dioxide particles can be titanium dioxide particles prepared by the chloride process. The titanium dioxide particles can have a rutile crystal structure, an anatase crystal structure, or a combination thereof. For example, the titanium dioxide particles can have a rutile crystal structure. For example, the titanium dioxide particles can have an anatase crystal structure.

[0055] In one embodiment, the organic treatment agent is a PHMS / PDMS copolymer. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount of at least about 0.5 wt% based on the weight of the inorganic pigment particles. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.5 wt% to about 5 wt% based on the weight of the inorganic pigment particles. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 1.5 wt% to about 4 wt% based on the weight of the inorganic pigment particles. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 1.5 wt% to about 3 wt% based on the weight of the inorganic pigment particles. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 2 wt% to about 3 wt% based on the weight of the inorganic pigment particles. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount of about 2.5 wt% based on the weight of the inorganic pigment particles.

[0056] For example, as shown in Example 4 below, when the organic treatment agent is a PHMS / PDMS copolymer, and the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 1.5 wt% to about 3 wt% based on the weight of the inorganic pigment particles, the packed bulk density of the treated inorganic pigment is in the range of about 0.55 g / cc to about 0.63 g / cc. Moreover, the bulk density is significantly increased compared to when PHMS is used as the organic treatment agent alone.

[0057] In another embodiment, the organic treatment agent is a combination of a PHMS / PDMS copolymer and a neat PHMS polymer. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.5 wt% to about 5 wt%, and the neat PHMS polymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.2 wt% to about 4 wt%, based on the weight of the inorganic pigment particles. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 1.5 wt% to about 4 wt%, and the neat PHMS polymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.5 wt% to about 3 wt%, based on the weight of the inorganic pigment particles. For example, in this embodiment, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 2 wt% to about 3 wt%, and the neat PHMS polymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.2 wt% to about 2 wt%, based on the weight of the inorganic pigment particles.

[0058] In one embodiment, the treated inorganic pigment further comprises an inorganic treatment agent deposited on the surface of the inorganic pigment particles and forming a coating of the inorganic treatment agent thereon. For example, the organic treatment agent can be deposited on top of the coating of the inorganic treatment agent.

[0059] For example, a first inorganic treatment agent can be deposited on the surface of the inorganic pigment particles to form a coating of the first inorganic treatment agent thereon, and a second inorganic treatment agent can be deposited on top of the coating of the first inorganic treatment agent to form a coating of the second inorganic treatment agent thereon. For example, the organic treatment agent can be deposited on top of the coating of the second inorganic treatment agent.

[0060] The inorganic treatment agent can be an inorganic treatment agent described above in connection with the methods disclosed herein. For example, the inorganic treatment agent is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.5 wt% to about 15 wt%, based on the combined weight of the inorganic pigment particles and the inorganic coating. For example, the inorganic treatment agent is deposited on the surface of the inorganic pigment particles in an amount ranging from about 1 wt% to about 10 wt%, based on the weight of the inorganic pigment particles.

[0061] The treated inorganic pigment can be formed by the methods disclosed herein.

[0062] In one embodiment, the method provided herein is a method for preparing treated titanium dioxide pigments. The method includes providing a plurality of titanium dioxide pigment particles and depositing an organic treatment agent on the surface of the pigment particles to form at least one coating of the organic treatment agent thereon. The organic treatment agent is selected from: PHMS / PDMS copolymers, and combinations of PHMS / PDMS copolymers and net PHMS polymers.

[0063] In another embodiment, the method provided herein is also a method for preparing treated titanium dioxide pigments. The method includes providing a plurality of titanium dioxide pigment particles and depositing an organic treatment agent on the surface of the pigment particles to form at least one coating of the organic treatment agent thereon. The organic treatment agent is selected from: PHMS / PDMS copolymers and combinations of PHMS / PDMS copolymers and net PHMS polymers, wherein the PHMS / PDMS copolymer contains PHMS in the range of about 20 wt% to about 80 wt%, and PDMS in the range of about 80 wt% to about 20 wt%, the weight percentages being based on the total weight of the copolymer.

[0064] In another embodiment, the method provided herein is also a method for preparing treated titanium dioxide pigments. The method includes: providing a plurality of titanium dioxide pigment particles to form a slurry of inorganic pigment particles; filtering the inorganic pigment particles to form a filter cake containing the inorganic pigment particles; and depositing an organic treatment agent onto the surface of the pigment particles by mixing the filter cake with the organic treatment agent to form at least one coating of the organic treatment agent thereon, wherein the organic treatment agent is selected from: PHMS / PDMS copolymers, and combinations of PHMS / PDMS copolymers and net PHMS polymers.

[0065] In one embodiment, the treated inorganic pigment provided herein is a treated titanium dioxide pigment. The pigment comprises a plurality of titanium dioxide pigment particles and an organic treatment agent deposited on the surface of the pigment particles and forming at least one coating thereon of an organic treatment agent, wherein the organic treatment agent is selected from: PHMS / PDMS copolymers, and combinations of PHMS / PDMS copolymers and net PHMS polymers.

[0066] In another embodiment, the treated inorganic pigment provided herein is also a treated titanium dioxide pigment. The pigment comprises a plurality of titanium dioxide pigment particles and an organic treatment agent deposited on the surface of the pigment particles, forming at least one coating thereon of an organic treatment agent. The organic treatment agent is selected from: PHMS / PDMS copolymers and combinations of PHMS / PDMS copolymers and net PHMS polymers, wherein the PHMS / PDMS copolymer contains PHMS in the range of about 20% to about 80% by weight, and PDMS in the range of about 80% to about 20% by weight, the weight percentages being based on the total weight of the copolymer.

[0067] In another embodiment, the treated inorganic pigment provided herein is also a treated titanium dioxide pigment. The pigment comprises a plurality of titanium dioxide pigment particles and an organic treatment agent deposited on the surface of the pigment particles and forming at least one coating thereon of an organic treatment agent. The organic treatment agent is a PHMS / PDMS copolymer, wherein the PHMS / PDMS copolymer comprises PHMS in the range of about 20 wt% to about 80 wt% and PDMS in the range of about 80 wt% to about 20 wt%, the weight percentages being based on the total weight of the copolymer, and wherein the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.5 wt% to about 5 wt% based on the combined weight of the inorganic pigment particles and the organic treatment agent.

[0068] In another embodiment, the treated inorganic pigment provided herein is also a treated titanium dioxide pigment. The pigment comprises a plurality of titanium dioxide pigment particles and an organic treatment agent deposited on the surface of the pigment particles and forming at least one coating thereon of an organic treatment agent. The organic treatment agent is a combination of a PHMS / PDMS copolymer and a net PHMS polymer, wherein the PHMS / PDMS copolymer comprises PHMS in the range of about 20 wt% to about 80 wt% and PDMS in the range of about 80 wt% to about 20 wt%, the weight percentages being based on the total weight of the copolymer, and wherein, based on the combined weight of the inorganic pigment particles and the organic treatment agent, the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.5 wt% to about 5 wt%, and the net PHMS polymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.2 wt% to about 4 wt%.

[0069] The organic treatment agents described herein, whether PHMS / PDMS copolymers themselves or combinations of PHMS / PDMS copolymers with net PHMS polymers, are relatively stable at high temperatures (e.g., up to 250°C), minimizing agent loss during subsequent pigment refining and processing. The reactivity of PHMS in the copolymer and in combination with net PHMS polymers is significantly reduced compared to PHMS used alone. Therefore, the problem of PHMS loss during high-temperature pigment processing (e.g., when PHMS is used alone) is solved. Hydrogen evolution is minimized. Surprisingly, as shown in the following examples, titanium dioxide pigments surface-treated with the organic treatment agents disclosed herein outperform titanium dioxide pigments treated with simple blends of PHMS and PDMS.

[0070] PDMS does not react with the pigment surface. On the other hand, PHMS reacts with the pigment surface due to its reactive hydrogen. In the case of a blend of PHMS and PDMS, two separate layers are formed. In the case of a PHMS / PDMS copolymer, due to the molecular-level distribution of PHMS and PDMS, the copolymer is uniformly coated onto the pigment as a monolayer.

[0071] The treated titanium dioxide pigments prepared by the methods described herein are well-suited for use in polymer compositions. As used herein and in the appended claims, "polymer composition" refers to a composition containing a polymer as one of its components. For example, a polymer composition may be a polymer masterbatch composition suitable for forming a variety of polymer and plastic products. Examples of polymer compositions in which the treated titanium dioxide pigments disclosed herein can be used include polyolefin polymer compositions, polyvinyl chloride polymer compositions, and polycarbonate (engineering plastic) compositions. The treated titanium dioxide pigments disclosed herein can enhance pigment / polymer compatibility and reduce the melt viscosity of thermoplastic polymers, thereby contributing to enhanced thermoplastic stability, optimized thermoplastic surface aesthetics, and improved overall processability of polymer compositions.

[0072] The treated titanium dioxide pigment prepared in this paper is highly suitable for use in combination with polycarbonate compositions. The pigment exhibits excellent rheological properties and other performance characteristics in polycarbonate compositions and articles.

[0073] Exemplary embodiments The following examples illustrate the processed inorganic pigments formed by the methods disclosed herein and the processed inorganic pigments disclosed herein.

[0074] Example 1 Thermogravimetric (TGA) study of polymers Thermochemical analysis (TGA) was performed on samples of PHMS polymers, PDMS polymers, and PHMS-PDMS copolymers using a general-purpose thermal analysis (TA) instrument. Polymer sample amounts ranging from 10 to 25 mg were used, with a heating rate of 10 °C / min in air. The weight loss of each polymer sample over time was analyzed as the temperature increased. The TGA curves for the samples are shown in the attached figure. Figures 1 to 4 middle.

[0075] Figure 1 The TGA curves of the PHMS polymer are shown. As shown in the figure, the PHMS polymer begins to lose weight at approximately 50°C, and significant weight loss occurs at approximately 270°C.

[0076] Figure 2 The TGA curves of the PDMS polymer are shown. As shown in the figure, the PDMS polymer begins to lose weight at approximately 330°C and is quite stable compared to net PHMS.

[0077] Figure 3 The TGA curve of a PHMS / PDMS copolymer (polymer 1 in Example 3C below), consisting of 30 wt% PHMS and 70 wt% PDMS, is shown. As shown, the copolymer begins to lose weight at approximately 286°C.

[0078] Figure 4 The TGA curves of a PHMS / PDMS copolymer (polymer 2 in Example 3C below), consisting of 70 wt% PHMS and 30 wt% PDMS, are shown. As shown, the copolymer begins to lose weight at approximately 223°C, and more significantly at 250°C.

[0079] These studies show that various polymers and copolymers behave differently in water as temperature increases. For example, the weight loss experienced by each polymer at approximately 250°C is significant. Once inorganic pigments such as titanium dioxide are coated with organic polymers, temperatures up to 250°C may be encountered in subsequent pigment refining steps.

[0080] Example 2 Investigation of hydrogen evolution with respect to polymers in Ti02 slurries Subsequently, hydrogen evolution studies were conducted on PHMS polymer and PHMS / PDMS copolymer samples. For each test, an aqueous slurry containing 50% by weight of titanium dioxide pigment was prepared. The pigment slurry and polymer or copolymer were then thoroughly mixed in a sealed container and heat-treated at various temperatures, with an equilibration time of approximately one minute at each temperature. Finally, the test mixture was heated to 280°C and then equilibrated for approximately 3 minutes.

[0081] In each test, the amount of hydrogen gas released was determined by gas chromatography using an HP5890II GC-TCD gas chromatograph equipped with a Carboxen 1000 column. The results are shown in Table 1 below: Table 1. Hydrogen evolution data of net PHMS and PHMS-PDMS copolymer at various temperatures when mixed with TiO2 slurry.

[0082] As shown, hydrogen evolution in PHMS begins at approximately 200°C and increases significantly at 240°C. For the PHMS-PDMS copolymer, some hydrogen evolution begins at 280°C. At 280°C, after equilibrating the sample for 3 minutes, the total percentage of hydrogen evolved was calculated based on the theoretical value of the total hydrogen in the polymer. Both copolymers exhibited lower hydrogen evolution than the net PHMS sample.

[0083] Example 3 Performance of siloxane treated Ti02 pigments in polycarbonate resin compositions A series of polycarbonate resin test samples were prepared by treating portions of the original titanium dioxide pigment samples with different amounts of PHMS, blends of PHMS and PDMS, and PHMS / PDMS copolymers to form corresponding treated pigment samples. These treated pigment samples were then combined with a certain amount of polycarbonate resin. The polycarbonate resin test samples were subsequently tested to evaluate the performance of the treated pigment samples, specifically, the effect of the treated pigments on the thermal stability of the resin. These tests are described in Examples 3A, 3B, and 3C below.

[0084] In preparing the treated pigment samples for testing, an aqueous inorganic pigment slurry containing 50% by weight solids based on the total weight of the slurry was first prepared. The inorganic pigment used was pristine titanium dioxide prepared by the chloride process, containing 0.8% alumina in its crystal lattice. The pigment was dispersed in water in the presence of 0.1% by weight (based on pigment) of sodium hexametaphosphate dispersant and a certain amount of sodium hydroxide sufficient to adjust the pH of the dispersion to a minimum of 9.5, to provide an aqueous pristine pigment slurry with a solids content of 35% by weight.

[0085] The original pigment slurry was then milled using a 4:1 zircon sand to pigment weight ratio until a volume average particle size was achieved, with over 90% of particles smaller than 0.63 micrometers, as determined using a Microtrac X100 particle size analyzer (Microtrac Inc. of Montgomeryville, PA). The slurry was then heated to 75°C, acidified to pH 2.0 with concentrated sulfuric acid, and digested at 75°C for 30 minutes. After the initial digestion period, the pH of the slurry was adjusted to 6.5 using a 20% by weight sodium hydroxide aqueous solution, and then further digested at 75°C for 30 minutes. After this digestion period, the pH was readjusted to 6.5 as needed, and the slurry was then filtered while hot. The resulting raw titanium dioxide filter cake was washed with a volume equal to the weight of the recovered pigment in preheated hot water (preheated to 60°C).

[0086] Example 3A - PHMS A first series of treated pigment test samples were prepared by adding various amounts of PHMS to a portion of a washed, raw titanium dioxide pigment filter cake prepared as described above. The amounts of PHMS used to form the treated pigment test samples were 2%, 2.5%, 3%, and 3.75%, each a weight percentage based on the weight of the filter cake. In preparing each treated pigment test sample, PHMS was added to a portion of the filter cake and mixed with it in the desired amount, thereby causing the PHMS to deposit on the surface of the pigment particles and form a coating thereon.

[0087] The treated pigment test samples were then dried overnight at 110°C. The dried pigments were crushed to obtain dried treated pigment powder. The dried treated pigment powder was then steam micronized using a steam-to-pigment weight ratio of 1.8, a steam injector pressure of 160 psi, and a micronizer ring pressure of 120 psi.

[0088] The treated pigment test samples were then added to a certain amount of polycarbonate resin to form the corresponding polycarbonate resin test samples. The resin used to prepare the polycarbonate resin test samples was Makrolon 3108 polycarbonate resin that had been dried at 125°C for 3 hours. The polycarbonate resin test samples were prepared as follows: using a Leistritz twin-screw extruder with a strand die attachment, a portion of the resin was loaded with treated pigment at 5% by weight of the resin. The temperature in zone 1 was 230°C. The temperature in zones 2 to 6 was 280°C. The die temperature was 280°C. The average screw speed was 50 rpm.

[0089] The resulting polycarbonate concentrate strips for each polycarbonate resin test sample were then cooled using a water trough, sliced ​​using a slicer, and dried in an oven at 125°C for 3 hours. The concentrates were then injection molded using a BOY injection molding machine to form the corresponding polycarbonate test articles. The baseline condition was 300°C for 1.75 minutes. The higher temperature condition was 360°C for 1.75 minutes. The color difference of each sample between the two conditions was then evaluated. The results are shown in Table 2 below: Table 2. Thermal stability data of polycarbonate resin samples prepared by coating TiO2 with different amounts of PHMS.

[0090] The results showed that as the PHMS content increased, b The values ​​become lower, and the Δb value also decreases, indicating that the polycarbonate sheet has good thermal stability. Therefore, the PHMS-treated titanium dioxide pigments function effectively in the polycarbonate polymer.

[0091] Example 3B - PHMS blend with PDMS Next, a second series of treated pigment test samples was prepared as described in Example 3A, except that in both test samples, a required amount of a blend of PHMS and 1% by weight of PDMS, instead of just PHMS, was added to and mixed with the washed raw titanium dioxide pigment filter cake based on the total weight of PHMS and PDMS. The amount of PHMS used to form the treated pigment test samples and the total amount of PHMS and PDMS were 3.75% (PHMS), 3% (PHMS), 3.75% (PHMS and PDMS), and 2.75% (PHMS and PDMS), respectively, as a weight percentage based on the weight of the filter cake. The PHMS and PDMS blend was deposited on the surface of the pigment particles to form one or more coatings thereon. Subsequently, each treated pigment test sample was dried and vapor-micronized, and combined with a certain amount of polycarbonate resin to form the corresponding polycarbonate resin test sample, as described in Example 3A. The resulting polycarbonate concentrate strips forming each polycarbonate resin test sample were then treated and tested as described in Example 3A. The results are shown in Table 3 below.

[0092] Table 3. Thermal stability data of polycarbonate resin samples prepared by coating TiO2 with different amounts of PHMS and PHMS with 1% PDMS.

[0093] The results showed that adding PDMS to PHMS to form a simple blend of PHMS and PDMS did not improve thermal stability. In fact, adding PDMS to PHMS to form a simple blend of PHMS and PDMS resulted in a slight deterioration in the thermal stability of the polycarbonate sheet. Therefore, the results confirm that combining PHMS and PDMS to form a simple polymer blend does not achieve a synergistic effect between PHMS and PDMS.

[0094] Example 3C - PHMS and PHMS / PDMS copolymer Finally, a third series of treated pigment test samples was prepared as described in Example 3A, except that in all but two of the test samples, a PHMS / PDMS copolymer, instead of just PHMS, was added to and mixed with the washed raw titanium dioxide pigment filter cake. The tests used treated pigment test samples formed from two different PHMS / PDMS copolymers: a first PHMS / PDMS copolymer formed from 30% by weight of PHMS and 70% by weight of PDMS (based on the total weight of the copolymer (“Copolymer 1”), and a second PHMS / PDMS copolymer formed from 70% by weight of PHMS and 30% by weight of PDMS (based on the total weight of the copolymer (“Copolymer 2”). Furthermore, different amounts of PHMS and Copolymer 1 were used to form the treated pigment test samples.

[0095] First, polycarbonate resin test samples were tested using pigment test samples containing PHMS, copolymer 1, and copolymer 1 with PHMS. The amounts of PHMS, copolymer 1, and copolymer 1 with PHMS are shown in Table 4 below. The percentages shown in Table 4 represent weight percentages based on the weight of the filter cake. Various polymers and / or copolymers are deposited on the surface of pigment particles to form one or more coatings thereon. For example, a single coating can be formed, or PHMS and the PHMS-PDMS copolymer can be randomly distributed on the pigment surface.

[0096] The treated pigment test samples were then dried and steam-micronized, and combined with a certain amount of polycarbonate resin to form corresponding polycarbonate resin test samples, as described in Example 3A. The resulting polycarbonate concentrate strips forming each polycarbonate resin test sample were then processed and tested as described in Example 3A. The results are shown in Table 4 below.

[0097] Table 4. Thermal stability data of polycarbonate resin samples prepared by coating TiO2 with different amounts of copolymer 1 (30% PHMS + 70% PDMS) and PHMS.

[0098] The results shown in Table 4 indicate that the test samples containing copolymer 1 exhibit better thermal stability compared to those containing only PHMS. An exception is the test sample containing only 2% copolymer 1. For example, the test sample prepared from only 2.5% copolymer 1 outperformed the test sample formed from only 2.5% PHMS. As shown in Examples 1 and 2, the test sample formed from 2.5% copolymer 1 showed the least weight loss and significantly less hydrogen release compared to the test sample formed from only 2.5% PHMS. Similarly, the combination of copolymer 1 with only 0.5% PHMS showed improved thermal stability and less weight loss and hydrogen evolution, further confirming the synergistic effect of the PHMS / PDMS copolymer.

[0099] Example 3D Subsequently, polycarbonate resin test samples were tested using pigment test samples containing copolymer 2 and copolymer 2 with PHMS. The amounts of copolymer 2 and copolymer 2 are shown in Table 5 below. The percentages shown in Table 5 represent weight percentages based on the weight of the filter cake. Various polymers and / or copolymers are deposited on the surface of pigment particles to form one or more coatings thereon. For example, a single coating can be formed, or PHMS and PHMS-PDMS copolymers can be randomly distributed on the pigment surface.

[0100] The treated pigment test samples were then dried and steam-micronized, and combined with a certain amount of polycarbonate resin to form corresponding polycarbonate resin test samples, as described in Example 3A. The resulting polycarbonate concentrate strips forming each polycarbonate resin test sample were then processed and tested as described in Example 3A. The results are shown in Table 5 below.

[0101] Table 5. Thermal stability data of polycarbonate resin samples prepared by coating TiO2 with different amounts of copolymer 2 (70% PHMS + 30% PDMS) and PHMS combination.

[0102] The results shown in Table 5 confirm that the test samples prepared from copolymer 2 performed much better than the test samples formed using only net PHMS, and suffered less weight loss.

[0103] Example 4 Subsequently, the treated pigment test samples formed from different amounts of copolymer 1 as described above and the treated pigment test samples formed solely from PHMS in the same manner were tested to determine their packed bulk density and dumped bulk density.

[0104] The bulk density of the pigments was measured using a standard Hosokawa Micron PT-E powder analyzer. The results are shown in Table 6 below.

[0105] Table 6. Comparison of bulk densities of pigments prepared with different contents of PHMS-PDMS copolymer and net PHMS.

[0106] The results showed that when the PHMS / PDMS copolymer was used as an organic treatment agent, the bulk density of the pigment samples (both filling and dumping) was significantly increased compared to when the PHMS polymer was used alone.

[0107] Therefore, pigments, compositions, and methods are well-suited to achieve the mentioned purposes and advantages, as well as those inherent herein. The specific embodiments disclosed above are merely exemplary, as the pigments, compositions, and methods of the invention can be modified and practiced in different but equivalent ways that will be apparent to those skilled in the art who have benefited from the teachings herein. Therefore, it is apparent that the specific exemplary embodiments disclosed above can be altered or modified, and all such changes are considered to be within the scope and spirit of the pigments, compositions, and methods of the invention. Although pigments, compositions, and methods are described as “comprising,” “containing,” “having,” or “including” various components or steps, in some embodiments, pigments, compositions, and methods may also “consist substantially of” various components or steps or “comprise” various components and steps. When a numerical range with a lower and upper limit is disclosed, any numerical value falling within that range and any range it includes is explicitly disclosed. Specifically, each numerical range disclosed herein (in the form of “about a to about b” or equivalently “generally a to b” or equivalently “generally ab”) should be understood to describe each numerical value and range covered within a wider numerical range. Furthermore, unless otherwise explicitly and clearly defined by the patentee, the terms in the claims have their ordinary, general meaning.

Claims

1. A method for preparing treated inorganic pigments, comprising: Multiple inorganic pigment particles are available; and An organic treatment agent is deposited on the surface of the pigment particles to form at least one coating of the organic treatment agent thereon, wherein the organic treatment agent is selected from: PHMS / PDMS copolymer, and a combination of PHMS / PDMS copolymer and net PHMS polymer.

2. The method of claim 1, wherein the inorganic pigment particles are provided by preparing pigment particles as part of the method.

3. The method according to claim 1, wherein the treated inorganic pigment is a treated titanium dioxide pigment, and the inorganic pigment particles are titanium dioxide pigment particles.

4. The method according to claim 3, wherein the titanium dioxide particles are titanium dioxide particles prepared by the sulfate method.

5. The method according to claim 3, wherein the titanium dioxide particles are titanium dioxide particles prepared by the chloride method.

6. The method of claim 1, wherein the PHMS / PDMS copolymer comprises about 20% by weight to about 80% by weight of PHMS and about 80% by weight to about 20% by weight of PDMS, the weight percentages being based on the total weight of the copolymer.

7. The method according to claim 1, wherein the organic treatment agent is a PHMS / PDMS copolymer.

8. The method of claim 7, wherein the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount of at least about 0.5% by weight, based on the weight of the inorganic pigment particles.

9. The method of claim 7, wherein the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 2% to about 3% by weight, based on the weight of the inorganic pigment particles, and the packed density of the treated inorganic pigment is in the range of about 0.55 g / cc to about 0.63 g / cc.

10. The method of claim 1, wherein the organic treatment agent is a combination of PHMS / PDMS copolymer and net PHMS polymer.

11. The method of claim 10, wherein the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.5% to about 5% by weight, and the net PHMS polymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.2% to about 4% by weight, the weight percentage being based on the combined weight of the inorganic pigment particles and the organic treatment agent.

12. The method of claim 1, further comprising: Before depositing the organic treatment agent on the surface of the inorganic pigment particles: The slurry that forms the inorganic pigment particles; and The inorganic pigment particles are filtered to form a filter cake containing the inorganic pigment particles, wherein the organic treatment agent is deposited on the surface of the inorganic pigment particles by mixing the organic treatment agent with the filter cake to form at least one coating of the organic treatment agent thereon.

13. The method of claim 1, further comprising: Before depositing the organic treatment agent on the surface of the inorganic pigment particles: An inorganic treatment agent is deposited on the surface of the inorganic pigment particles to form a coating of the inorganic treatment agent thereon.

14. The method of claim 13, wherein the organic treatment agent is deposited on top of the coating of the inorganic treatment agent to form a coating thereon.

15. The method according to claim 13, wherein the inorganic treatment agent is selected from metal oxide materials and metal hydroxide materials.

16. A method for preparing treated titanium dioxide pigment, comprising: Multiple titanium dioxide pigment particles are available; An inorganic treatment agent is deposited on the surface of the titanium dioxide pigment particles to form a coating of the organic treatment agent thereon. An organic treatment agent is deposited on top of the coating of the inorganic treatment agent to form at least one coating of the organic treatment agent thereon, wherein the organic treatment agent is selected from: PHMS / PDMS copolymer, and a combination of PHMS / PDMS copolymer and net PHMS polymer.

17. The method of claim 16, wherein the organic treatment agent is a PHMS / PDMS copolymer.

18. The method of claim 16, wherein the organic treatment agent is a combination of a PHMS / PDMS copolymer and a net PHMS polymer.

19. The method of claim 16, further comprising: Before depositing the organic treatment agent onto the coating of the inorganic treatment agent: A slurry for forming the titanium dioxide pigment particles, wherein the inorganic treatment agent is deposited on the surface of the titanium dioxide pigment particles by precipitating the inorganic treatment agent onto the titanium dioxide pigment particles in the slurry, thereby forming a coating of the inorganic treatment agent thereon. and The slurry is filtered to form a filter cake containing the surface-treated titanium dioxide pigment particles, wherein the organic treatment agent is deposited on the coating of the inorganic treatment agent by mixing the organic treatment agent with the filter cake to form at least one coating of the organic treatment agent thereon.

20. Processed inorganic pigments, comprising: Multiple inorganic pigment particles; and An organic treatment agent is deposited on the surface of the inorganic pigment particles and forms at least one coating thereon, wherein the organic treatment agent is selected from: PHMS / PDMS copolymers, and combinations of PHMS / PDMS copolymers and net PHMS polymers.

21. The pigment of claim 20, wherein the treated inorganic pigment is a treated titanium dioxide pigment, and the inorganic pigment particles are titanium dioxide pigment particles.

22. The pigment of claim 20, wherein the PHMS / PDMS copolymer comprises about 20% by weight to about 80% by weight of PHMS and about 80% by weight to about 20% by weight of PDMS, the weight percentages being based on the total weight of the copolymer.

23. The pigment according to claim 20, wherein the organic treatment agent is a PHMS / PDMS copolymer.

24. The pigment of claim 23, wherein the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.5% to about 5% by weight, based on the combined weight of the inorganic pigment particles and the organic treatment agent.

25. The pigment of claim 23, wherein the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 1.5% by weight to about 3% by weight, and the bulk density of the treated inorganic pigment is in the range of about 0.55 g / cc to about 0.63 g / cc.

26. The pigment of claim 20, wherein the organic treatment agent is a combination of a PHMS / PDMS copolymer and a net PHMS polymer.

27. The pigment of claim 26, wherein the PHMS / PDMS copolymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.5% to about 5% by weight, and the net PHMS polymer is deposited on the surface of the inorganic pigment particles in an amount ranging from about 0.2% to about 4% by weight, the weight percentage being based on the combined weight of the inorganic pigment particles and the organic treatment agent.

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