HK1155769A

HK1155769A - Titanium dioxide

Info

Publication number: HK1155769A
Application number: HK11110160.0A
Authority: HK
Inventors: J．罗伯; J.L.爱德华兹; J．泰姆佩里; R．比尔德; P．C．布兰德雷; A.G.琼斯
Original assignee: 钛白粉欧洲有限公司
Priority date: 2008-05-07
Filing date: 2009-05-01
Publication date: 2012-05-25

Description

Titanium dioxide

Embodiments of the present invention generally relate to titanium dioxide, and more particularly to titanium dioxide particulate materials and compositions.

In some embodiments, the titanium dioxide or doped titanium dioxide particulate material is effective to scatter infrared radiation in the Near Infrared (NIR) spectral region. In one embodiment of the composition, the particulate material is combined with a non-white colorant having low absorbance in the NIR spectral region.

In some embodiments, the titanium dioxide or doped titanium dioxide particulate material is coated and has ultra-low photocatalytic activity. Thus, products containing such materials may have improved photostability relative to similar products containing conventional titanium dioxide.

Background

The NIR region of the electromagnetic spectrum is located at 700 and 2500 nm. Materials with high reflectivity and reduced absorption in this range may be advantageous in many applications. For example, products made from such materials tend to remain cooler under solar illumination and lower temperatures can result in lower thermal degradation, improved durability, greater comfort, lower air conditioning costs, and reduced environmental impact.

A current environmental concern (and cost factor) is to reduce the amount of air conditioning required to cool a building. One way to reduce the cost of air conditioning is to use roofing products that reflect solar energy. The U.S. Environmental Protection Agency (EPA) Energy Star Initiative requires a steeply pitched (inclined) residential roof with a minimum Total Solar Reflectance (TSR) of 25%. Lighter colored products may reach this minimum, but due to their nature, dark or strongly colored products cannot do so and tend to have TSRs much less than 25%, e.g., 10% or less. This can be problematic for those who consider dark or intense colors aesthetically pleasing, and require the advantages of a higher TSR.

High solar reflectance can be achieved in different ways. For example, an article having a white outer surface may have a high solar reflectance, but this approach is unsatisfactory if color is desired. Alternatively, it is possible to use conventional TiO by₂The pigments combine with non-NIR absorbing colored pigments and dyes to achieve high solar reflectance. This approach is also limited because of the requirement for conventional TiO to impart the desired level of solar reflectance₂The level of pigment will necessarily result in a lighter color. Thus, darker or stronger colors are not possible in such reflective formulations. In yet another alternative, a white layer with high solar reflectance may be applied to the article followed by a layer containing NIR transparent colour pigments. Such pigmented topcoats do not reflect or absorb NIR radiation. This system is also undesirable because it takes time to apply two different coats, which if not properly applied results in a "patchy" appearance, the white basecoat appears partially through the pigmented topcoat, and the color may brighten over time as the topcoat weathers away, exposing more of the basecoat.

Thus, there remains a need for high total solar reflective materials that can be obtained in a darker or stronger color range for a given solar reflectance than would otherwise be obtainable. These colors include medium hues and even darker/stronger hues (pastels). In addition, there remains a need for a coating system for applying such solar reflective pigmented materials that can be used in a range of applications including roofing surfaces, plastic articles, pavement and paints. In this way, consumers may then have articles that they desire while having the desired colored appearance and good total solar reflection. Those items may then contribute to a cooler living environment and/or reduced air conditioning energy usage, thermal degradation of the environmental footprint and/or contribution to global warming.

Furthermore, articles exposed to sunlight may not be light stable and may degrade prematurely. Such articles (including paints, plastic products, roofing products, and floor covering products) may contain titanium dioxide. Although titanium dioxide itself does not degrade, the degree of degradation of the titanium dioxide-containing article may depend on the photocatalytic activity of the titanium dioxide pigment used in the article.

For example, and without wishing to be bound by theory, if the titanium dioxide crystals absorb UV light, it is believed that the electrons are pushed to a higher energy level (conduction band) and pass through the lattice. The resulting holes or "pores" in the valence band are also effectively "mobile". If these mobile charges reach the crystal surface, they can be transferred to the media of the article containing titanium dioxide (e.g., the resin media of a paint) and generate free radicals that degrade the media.

Thus, there remains a need for titanium dioxide particles having ultra-low photocatalytic activity. Such titanium dioxide particles may then be used to improve the lifetime of articles exposed to sunlight. For example, such titanium dioxide particles may be used in combination with high light stability resins, paint binders, and the like to extend the overall life of the sun exposed article.

Summary of The Invention

In a first aspect of the invention, the invention provides a colouring composition comprising:

a NIR scattering particulate material selected from titanium dioxide, doped titanium dioxide and combinations thereof, the material having an average crystal size greater than 0.40 μm and a particle size distribution such that 30% or more of the particles are less than 1 μm; and

one or more non-white colorants;

wherein the particulate material and the non-white colorant are dispersed within a carrier.

Such particulate materials with large crystal sizes have an exceptionally high reflection of NIR radiation and at the same time a significantly reduced reflection of visible light compared to conventional pigments. This surprising effect means that low levels of such NIR scattering agents can still achieve good NIR reflection levels. An additional advantage is that lower levels of non-white colorants are required to achieve any given darker or stronger color.

Surprisingly, particulate materials that are large crystalline titanium dioxide or doped titanium dioxide are blended in compositions having darker, or more intensely colored colorants without unduly affecting the color of the composition. In contrast, conventional TiO₂The pigment is very reflective of visible light and clearly affects the color of the composition, making it noticeably lighter. Thus, for use in the present invention is a particulate material of large crystalline titanium dioxide or doped titanium dioxide blended in a composition with a darker, or more strongly colored colorant, rather than being as in conventional TiO₂The pigment then greatly affects the color.

In a first part of the invention, the invention also provides in a second aspect the use of a composition according to the first aspect to provide a single coat covering having solar reflectance and a non-white colour or to produce an article having solar reflectance and a non-white colour.

In a first aspect of the invention, the invention also provides the use, in a third aspect, of a NIR scattering particulate material selected from titanium dioxide, doped titanium dioxide and combinations thereof, having an average crystal size greater than 0.40 μm and having a particle size distribution such that 30% or more of the particles are less than 1 μm, to increase the level of solar reflection (preferably whilst also reducing the level of visible light reflection) of a colouring composition.

In a fourth aspect, the present invention also provides, in the first part of the invention, an article comprising a composition according to the first aspect.

In a second aspect thereof, the present invention provides a coated particulate material in a first aspect, wherein:

(i) the material is selected from the group consisting of titanium dioxide, doped titanium dioxide, and combinations thereof;

(ii) the material has an average crystal size greater than 0.40 μm; and

(iii) the coating comprises one or more oxide materials, wherein the materials are oxides of one or more elements that are:

(a) transition metals of groups 4(IVB) and 12(IIB) selected from Ti, Zr and Zn and/or

(b) Group 13-15(IIIA-VA) P-block element selected from Si, Al, P and Sn and/or

(c) A lanthanide series element.

Surprisingly, it has been found that by combining large crystalline titanium dioxide or large crystal doped titanium dioxide with conventional milling and coating techniques, improved products containing titanium dioxide particles can be obtained with previously unattainable low levels of photocatalytic activity.

The coated particulate material is substantially white. Preferably, the product has a brightness value L (CIE L a b color space) of more than 95, with a value of less than 5 and b value of less than 5.

In a second aspect of the invention, the invention also provides the following in a second aspect

(i) An average crystal size greater than 0.40 μm; and

(ii) a coating comprising one or more oxide materials, wherein the materials are oxides of one or more elements that are:

(b) Group 13-15(IIIA-VA) P-block element selected from Si, Al, P and Sn and/or

(c) Lanthanide series element

Use to reduce the photocatalytic activity of a material selected from the group consisting of titanium dioxide, doped titanium dioxide, and combinations thereof.

In a second aspect of the invention, the invention also provides the use of a material according to the first aspect of the second part to improve the durability and/or lifetime of a product exposed to sunlight during use.

In a second aspect of the invention, the invention also provides a product exposed to sunlight during use, the product comprising a material according to the first aspect of the second aspect. Detailed Description

A. First part-solar reflective coloring product

The present invention provides in a first aspect a colouring composition comprising:

one or more non-white colorants;

Preferably, the non-white colorant has low absorbance in the NIR portion of the spectrum. In one embodiment, the non-white colorant may have 50mm in the NIR region of 700 and 2500nm^-1Or a lower average absorption coefficient. Preferably, the non-white colorant may have a 20mm spectrum in the range of 700-^-1Or lower, e.g. 15mm^-1Or lower, e.g. 12mm^-1Or lower, e.g. 10mm^-1Or a lower average absorption coefficient.

Such compositions have the colorant and particulate material mixed together in one composition while achieving the desired solar reflection effect.

Such particulate materials with large crystal sizes have an exceptionally high reflection of NIR radiation and at the same time a significantly reduced reflection of visible light compared to conventional pigments. This surprising effect means that low levels of such NIR scattering agents can still achieve good NIR reflection levels. An additional advantage is that lower levels of non-white colorants are required to achieve any given color.

Surprisingly, particulate materials that are large crystalline titanium dioxide or doped titanium dioxide are blended in compositions having darker, or more intensely colored colorants without unduly affecting the color of the colorant. In contrast, conventional TiO₂The pigment is very reflective of visible light and clearly affects the color of the composition, making it noticeably lighter. Thus, for use in the present invention is a particulate material of large crystalline titanium dioxide or doped titanium dioxide blended in a composition with a darker, or more strongly colored colorant, rather than being as in conventional TiO₂The pigment then greatly affects the color.

The present compositions allow the NIR reflective coating to be applied in one application. Such a one-pass solar reflective coating provides advantages in terms of application speed and resulting application cost, as well as color uniformity across the surface.

JP2005330466A describes IR-reflective particles of 0.5 to 1.5 μm diameter (which may be TiO)₂) The use of said particles coated with a resin film transparent to IR radiation. The film coating may contain substantially non-IR-absorbing pigments. However, although these products have a large particle size, they are not described as being made of large crystal size titanium dioxide as in the products of the present invention. As discussed in more detail below, TiO₂The particle size and crystal size of the particles are not the same. The prior art products do not use large crystal size TiO₂The fact that (c) creates a number of technical differences between those products and the products of the invention.

In particular, large (e.g. 1 micron diameter) particles formed from conventional (pigmentary) titanium dioxide crystals would be impractical for processing. In contrast, the present invention uses large crystal sizes that provide practical and durable goods. Furthermore, in the present invention, less material is required to achieve equivalent IR reflection compared to products using conventional (pigmentary) titanium dioxide crystals. Furthermore, the product of JP2005330466A does not exhibit the surprising advantages of the present invention, wherein the IR reflectance is increased while the visible reflectance is decreased, which results in a lower level of non-white colorant required to achieve any given color in the present invention as compared to the prior art. Furthermore, as can be seen from the densities indicated in this document, these products are uncoated and therefore prone to damaging photocatalysis, which is a major obstacle in any composition or product designed for exposure to solar radiation.

US2007065641 describes a composition containing crude TiO₂And roofing granules of pigmented IR reflector granules. The particle size distribution is broad: 100% is less than 40 microns, 50-100% is less than 10 microns, 0-15% is less than microns. This is similar to the specifically defined particle size distribution required by the present invention for 30% or more of the particles to have a particle size of less than 1 micron. The particles described in US2007065641 will be coarse and gritty and prone to caking and therefore not suitable for many uses, such as decorative applications.

US2008/0008832 relates to the use of a coating which may be coated with TiO₂The pigmented core of (a) forms a roofing granule. WO2005/095528 relates to TiO-containing materials₂And a heat-reflective coloring pigment component. In both documents, TiO₂Are pigments and do not have the large crystal size required by the present invention.

The prior art does not identify or suggest the benefits in formulating a coloring composition with excellent weatherability and solar reflectance that are surprisingly achieved by obtaining a coloring composition using NIR scattering particulate materials with both large crystal size and defined particle size distribution with colorants.

Such compositions may include only a single type of NIR scattering particulate material or may include two or more different types of NIR scattering particulate materials.

The NIR scattering particulate material for use in the present invention is titanium dioxide or doped titanium dioxide (or a combination thereof) and has an average crystal size greater than 0.40 μm and a particle size distribution such that 30% or more of the particles are less than 1 μm. Such materials surprisingly efficiently scatter in the NIR spectral region (700 and 2500 nm). However, it absorbs strongly in the UV region (300-400 nm). It has low scattering and low absorption in the visible spectral region (400-700 nm).

Surprisingly, the high refractive index of NIR scattering particulate materials outweighs the disadvantage of having strong solar uv absorption, while imparting excellent total solar reflectance. The strong solar uv absorption of these particles also imparts the advantageous property of high solar uv opacity, i.e., the property of increasing the weatherability of any article exposed to sunlight.

In one embodiment, the particulate material is or includes doped titanium dioxide, i.e. TiO containing inorganic material₂. The doped titanium dioxide may have 10 wt% or more, preferably 12 wt% or more of TiO₂And (4) content.

The doped titanium dioxide may be in the rutile or anatase crystalline form. Preferably, the doped titanium dioxide has a rutile crystal structure. As will be appreciated by those skilled in the art, it need not be rutile, but may be a material that is iso-structured from rutile.

In the present invention, the rutile crystal form may be preferred due to its higher refractive index. This means that less is required to achieve a given NIR reflectance and, when optimised, the effect is greater. For example, it may be 50% or more rutile, such as 60% or more, for example 70% or more, preferably 80% or more, more preferably 90% or more, most preferably 95% or more, such as 99% or more, for example 99.5% or more by weight.

For example, doped titanium dioxide may be doped with dopants such as calcium, magnesium, sodium, aluminum, antimony, phosphorus, and cesium.

The doped titania may include impurities, for example, at a level of up to 10 wt% or less, such as 8 wt% or less, for example 5 wt% or less. These impurities originate from incomplete purification and may, for example, be iron, silicon oxide, niobium oxide or other impurities usually present in titanium dioxide bearing raw materials.

In one embodiment, the particulate material is or includes titanium dioxide. The titanium dioxide may be prepared by any known method. For example, the so-called "sulfate" route or the so-called "chloride" route, which are two routes in a wide range of commercial applications, may be used. Likewise, a fluoride process, a hydrothermal process, an aerosol process, or a leaching process may be used to produce titanium dioxide.

The titanium dioxide may be in the rutile or anatase crystal form. In the present invention, the rutile crystal form may be preferred due to its higher refractive index. This means that less is required to achieve a given NIR reflectance and, when optimised, the effect is greater.

In one embodiment, the titanium dioxide is 50% or more rutile, such as 60% or more, for example 70% or more, preferably 80% or more, more preferably 90% or more, most preferably 95% or more, for example 99% or more, such as 99.5% or more by weight.

The titanium dioxide may be white or translucent or may be coloured. In one embodiment, it may be substantially white; for example, it may have a luminance value L (CIEL a b color space) greater than 95, with a value less than 5 and b value less than 5.

The doped titania may include impurities, for example, at a level of up to 10 wt% or less, such as 8 wt% or less, for example 5 wt% or less. These impurities originate from incomplete purification and may, for example, be iron, silicon oxide, niobium oxide or other impurities usually present in titanium dioxide bearing raw materials. Preferably, the titanium dioxide has 90 wt% or more, such as 92 wt% or more, such as 93 wt% or more of TiO₂And (4) content.

In the present invention, the NIR scattering particulate material has an average crystal size of greater than or equal to 0.40 μm. Preferably, the NIR scattering particulate material has an average crystal size of greater than or equal to 0.45 μm. Preferably, the average crystal size is greater than or equal to 0.50 μm, such as 0.55 μm or greater, more preferably 0.60 μm or greater, such as 0.70 μm or greater, for example 0.80 μm or greater.

In one embodiment, the NIR scattering particulate material has an average crystal size of greater than 0.40 μm and up to 1.20 μm, for example from 0.45 to 1.1 μm, more preferably from 0.50 to 1.1 μm, for example from 0.60 to 1.0 μm, for example from 0.70 to 1.00 μm.

The average crystal size can be determined by transmission electron microscopy on the polished sample in the case of a photograph obtained by image analysis (for example using a Quantimet 570 image analyser). This can be achieved by reference to NIST-derived latex NANOSPHERE with a guaranteed size of 199+/-6nm^TMThe size criteria 3200 validation.

Conventional rutile TiO₂Having an average crystal size of 0.17-0.29 μm, compared to conventional anatase TiO₂Having an average crystal size of 0.10-0.25 μm.

The crystal size is different from the particle size. The particle size depends on the effectiveness of the dispersion of the pigment in the system in which it is used. Particle size is determined by factors such as crystal size and milling techniques, such as dry, wet or combined milling. Conventional rutile TiO₂Has a particle size of 0.25-0.40 μm compared to conventional anatase TiO₂Having a particle size of 0.20-0.40 μm. Larger particle sizes may result if the technique used causes the crystals to "clump" together.

In the present invention, the NIR scattering particulate material has an average particle size, as determined by X-ray sedimentation, of greater than 0.40 μm. For example, the average particle size may be greater than 0.40 μm and up to 1.2 μm. Preferably, the average particle size is greater than or equal to 0.45 μm, such as from 0.45 to 1.1 μm, such as from 0.50 to 1.0 μm, more preferably from 0.60 to 1.0. mu.m.

In the present invention, the NIR scattering particulate material has a particle size distribution such that 30% or more of the particles are less than 1 μm. In one embodiment, the NIR scattering particulate material has a particle size distribution such that 35% or more of the particles are less than 1 μm, for example 40% or more of the particles are less than 1 μm. In the present application, when referring to a percentage of particles having a given size, this refers to the weight percentage.

To measure particle size, the product is subjected to high shear mixing in the presence of a suitable dispersant to disperse the particles without comminution. Particle size distribution was measured using a Brookhaven XDC X-ray disk centrifuge. The average particle size and particle size geometric weight standard deviation are reported.

The NIR scattering particulate material may be treated or coated as is known in the art.

As the skilled person will appreciate, the NIR scattering particulate material (being titanium dioxide, doped titanium dioxide or a combination thereof) is prepared via a process comprising a milling step. The particles resulting from the milling step may be coated, for example with a hydrated oxide such as silica, alumina or zirconia; such a coating step may result in reduced photocatalytic activity, improved dispersibility, reduced yellowness or better opacity.

For example, the particles may be coated with an inorganic or organic coating at a level of up to 20% wt/wt, for example 0.5 to 20% wt/wt.

In one embodiment, an inorganic coating selected from inorganic oxides, hydroxides, and combinations thereof may be used. An example of these materials (expressed as their oxides) is Al₂O₃、SiO₂、ZrO₂、CeO₂And P₂O₅。

Organic surface treatments, such as with polyols, amines (e.g., alkanolamines), or silicone derivatives, may also be present. In particular, this may improve the dispersing ability. Typical organic compounds used are trimethylolpropane, pentaerythritol, triethanolamine, alkylphosphonic acids (e.g. n-octylphosphonic acid) and trimethylolethane.

The coating process of the NIR scattering particulate material (being titanium dioxide, doped titanium dioxide or a combination thereof) is similar to that of conventional pigmentary materials known in the art and comprises dispersing the material in water followed by the addition of a suitable coating agent, such as aluminium sulphate. The pH is then adjusted to cause precipitation of the desired hydrated oxide to form a coating on the surface of the material.

After the coating is formed, the material may be washed and dried prior to grinding (e.g., in a fluid energy mill or a micronizer) to isolate particles that have been stuck together by the coating.

In this final grinding stage, an organic surface treatment may be applied as desired, for example with a polyol, amine, alkylphosphonic acid or silicone derivative.

In one embodiment, the NIR scattering particulate material may be treated to selectively remove specific size fractions prior to use in the composition. For example, any particles 5 μm or more in diameter may be removed; in one embodiment, any particles having a diameter of 3 μm or greater may be removed. For example, such particles may be removed by centrifugation.

In the first aspect, the colouring composition may comprise NIR scattering particulate material in an amount of from 0.5 to 70 vol%, for example from 1 to 60 vol%, for example from 2 to 50 vol%.

The level of NIR scattering particulate material in the application may be suitably selected, depending on the intended application.

In one embodiment, the composition is intended for use as a paint, and the composition may comprise the NIR scattering particulate material in an amount of from 5 to 50% v/v, for example from 10 to 30% v/v, for example from 15 to 20% v/v. As the skilled artisan will appreciate, more non-white colorant may be required as more NIR scattering particulate material is added in order to maintain the same color.

In one embodiment, the composition is intended for use as a plastic resin composition, and the composition may comprise NIR scattering particulate material in an amount of from 0.5 to 70% v/v; for example, in a masterbatch, a content of up to 50-70% v/v may be possible or desirable.

In one embodiment, the composition is intended for use as a coating composition for roofing or ground covering products (e.g. road surfaces, sidewalks or floors), such as a surface coating composition for asphalt or tar, and the composition may comprise NIR scattering particulate material in an amount of 1-50% v/v.

Such compositions may include only a single type of non-white colorant or may include two or more different types of non-white colorants.

The non-white colorant may be selected from any known colorant, such as pigments and dyes. The colorant may include a blue, black, brown, cyan, green, violet, magenta, red, orange, or yellow colorant.

Pigments that may be used as colorants include, but are not limited to, pearlescent pigments, deep blue pigments, fluorescent pigments, inorganic pigments, carbon pigments, phosphorescent pigments, and organic pigments. Mixtures of these different types of pigments may also be used.

The non-white colorant may be selected from carbon pigments, organic colored pigments, and inorganic colored pigments in one embodiment.

Examples of carbon products include graphite, carbon black, glassy carbon, activated carbon, carbon fiber, or activated carbon black. Representative examples of carbon black include channel black, furnace black, and lamp black.

Organic colored pigments include, for example, anthraquinones, phthalocyanine blues, phthalocyanine greens, diazos, monoazos, pyranthrones, perylenes, heterocyclic yellows, quinacridones, quinolonoquinolones (quinophthalones) and (thio) indigoids.

Inorganic pigments that may be used include cobalt pigments, copper pigments, chromium pigments, nickel pigments, iron pigments, and lead pigments.

Examples of pigments are cobalt chromite, cobalt aluminate, copper phthalocyanine, hematite, chromium titanate yellow, nickel titanate yellow, synthetic red iron oxides, perylene black and quinacridone red.

Preferably, the non-white colorant or colorants will be selected from non-white colorants having low absorbance in the NIR spectral region. Examples of such colorants are chromium titanate yellow, nickel titanate yellow, synthetic red iron oxide,Black, copper phthalocyanine and quinacridone red.

The composition may comprise the non-white colorant in an amount of 0.1 to 20 vol%, such as 0.5 to 15 vol%, such as 1 to 10 vol%, for example about 1 vol%.

In one embodiment, the colorant is separate from the NIR scattering agent rather than being provided with the NIR scattering agent as a single particle. There is a practical advantage to having the NIR scattering agent and colorant separate, i.e. this allows for formulation freedom for those manufacturing applications: thereby enabling wider applications. However, in alternative embodiments, the colorant is provided with the NIR scattering agent in individual particles, for example the colorant is provided in a coating on the NIR scattering agent or the NIR scattering agent is provided as a coating on a core containing the colorant.

The carrier may be any product or combination of products in which the NIR scattering particulate material and the non-white colorant may be dispersed. For example, it may be a carrier or a solvent or binder. In one embodiment, the support is or includes a synthetic or natural resin.

Suitable plastic resins include general-purpose resins such as polyolefin resins, polyvinyl chloride resins, ABS resins, polystyrene resins, and methacrylic resins; and engineering plastic resins such as polycarbonate resins, polyethylene terephthalate resins, and polyamide resins. It may be or include a lacquer resin binder such as an acrylic resin, a polyurethane resin, a polyester resin, a melamine resin, an epoxy resin or an oil. It may be or include a bitumen/tar binder for road or roofing applications. In one example, the carrier is or includes a polyester resin such as an alkyd resin. In one embodiment, the carrier is or includes an aqueous carrier or solvent, such as water. In one embodiment, the carrier is or includes a non-aqueous carrier or solvent, such as an organic carrier or solvent. The carrier or solvent may, for example, be an aliphatic solvent, an aromatic solvent, an alcohol or a ketone. They include organic carriers or solvents such as petroleum distillates, alcohols, ketones, esters, glycol ethers, and the like.

In one embodiment, the carrier is or includes a binder, which may be, for example, a metal silicate binder, such as an aluminosilicate binder, or a polymeric binder, such as an organic polymeric binder, such as an acrylic polymeric binder or an acrylic copolymer binder.

The tinting composition may be a coating composition that may be used to coat a surface, or may be a composition that may be formed into an article, for example, via molding or other methods.

In one embodiment, the coloring composition is a plastic resin composition. In another embodiment, the coloring composition is a paint. In another embodiment, the coloring composition is an ink. In one embodiment, the tinting composition is a powder coating.

In one embodiment, the coloring composition is a component of or used to treat a textile. The colouring composition may also be a leather treatment composition.

In one embodiment, the coloring composition is a coating composition for roofing or floor covering products (e.g., pavement products, flooring products, roadway surface products, parking lot surface products, or pavement surface products). For example, it may be a composition that coats the surface of the bitumen or tar product.

The composition may optionally include other additives. They may include, but are not limited to, thickeners, stabilizers, emulsifiers, conditioners, adhesion promoters, UV stabilizers, matting agents, dispersants, defoamers, wetting agents, coalescing solvents, and biocides, including fungicides.

In one embodiment, the composition comprises spacer particles. They are components that serve to space or support the particles included in the composition. These particles may optionally contribute some pigment effect to the composition. The spacer particles serve to reduce the scattering efficiency loss of the NIR scattering particulate material due to the "jamming effect".

The size of any spacer particles used may vary within fairly wide limits. In general, the size will depend on the nature of the particles. The average size of the spacer particles is in one embodiment 0.02 to 40 μm.

For example, the spacer particles may be silica, silicate, aluminate, sulphate, carbonate or clay or polymeric particles, for example in the form of hollow polymeric beads or in the form of microspheres, for example beads or microspheres comprising polystyrene, polyvinyl chloride, polyethylene or acrylic polymers. Preferably, the spacer particles are heteroflocculated (heteroflocculated), as described in EP 0573150.

These spacer particles can improve the aesthetics of the composition and the overall solar reflectance.

Surprisingly, the compositions of the present invention not only have improved NIR reflectivity, but also reduced tinting strength.

The preparation of NIR scattering particulate materials having an average crystal size greater than 0.40 μm and a particle size distribution such that 30% or more of the particles are less than 1 μm may be carried out by standard methods for obtaining such materials, modified to apply one or more of the following:

a) calcining at a higher temperature than standard, such as 900 ℃ or higher, such as 1000 ℃ or higher;

b) calcination is maintained for longer than standard, e.g., 5 hours or more;

c) there is a reduced level of growth moderator during the process; for example, it may be that growth moderators are not present during the process;

d) adding a growth promoter during the process; especially the addition of increased levels of growth promoters during the process;

e) the level of rutile seeds in the calciner feed pulp is reduced.

The large crystal material can be treated in the same way as conventional pigments, for example with various additions which render it compatible in paints, plastics, asphalts or other vehicles.

A method of obtaining a NIR scattering titanium dioxide particulate material having an average crystal size greater than 0.40 μm and a particle size distribution such that 30% or more of the particles are less than 1 μm may comprise:

reacting a titaniferous material with sulfuric acid to form a solid, water-soluble reaction cake;

dissolving the filter cake in water and/or a weak acid to produce a solution of titanium sulfate;

hydrolyzing the solution to convert the titanium sulfate to titanium dioxide hydrate;

separating the precipitated titanium dioxide hydrate from the solution and calcining to obtain titanium dioxide;

wherein one or more of the following applies:

b) calcination is maintained for longer than standard, e.g., 5 hours or more;

e) the level of rutile seeds in the calciner feed pulp is reduced.

Rutile promoters that may optionally be present during calcination include lithium and zinc compounds. The rutile inhibitors whose presence should be controlled include aluminum, potassium and phosphorus compounds.

The titanium dioxide particulate material may be coated as follows: the material is dispersed in water, after which a suitable coating agent, such as aluminium sulphate, is added. The pH is then adjusted to cause precipitation of the desired hydrated oxide to form a coating on the surface of the material.

After the coating is formed, the material may be washed and dried prior to grinding (e.g., in a fluid energy mill or a micronizer) to isolate particles that have been stuck together by the coating. In this final grinding stage, an organic surface treatment, for example with polyols, amines or silicone derivatives, may be applied as required.

In one embodiment, the titanium dioxide particulate material may be treated to selectively remove specific size fractions prior to use in the composition.

The present invention provides in a second aspect the use of a composition according to the first aspect to provide a single coat covering having solar reflectance and a non-white colour or to produce an article having solar reflectance and a non-white colour.

In one embodiment, the cover has a brightness value L (CIE L a b color space) of 75 or less, such as 65 or less, such as 55 or less, preferably 45 or less, such as 35 or less, such as 25 or less.

Preferably, the solar reflectance achieved is 20% or higher, such as 25% or higher Total Solar Reflectance (TSR).

Preferably, the composition is used to provide a single coat covering having solar reflectance and a dark or intense color.

The present invention provides in a third aspect the use of an NIR scattering particulate material selected from titanium dioxide, doped titanium dioxide and combinations thereof, having an average crystal size greater than 0.40 μm and having a particle size distribution such that 30% or more of the particles are less than 1 μm, to increase the level of solar reflection (preferably whilst also reducing the level of visible light reflection) of a coloured composition, for example a dark or intensely coloured composition.

In one embodiment, the coloring composition has a brightness value L (CIE L a b color space) of 75 or less, such as 65 or less, such as 55 or less, preferably 45 or less, such as 35 or less, such as 25 or less.

In one embodiment, NIR scattering particulate material is used to obtain a Total Solar Reflectance (TSR) of 20% or more, for example 25% or more, for dark or strongly coloured compositions.

Preferred features of the NIR scattering particulate material are as described above in relation to the first aspect.

In a fourth aspect, the present invention provides an article comprising a composition according to the first aspect.

In one embodiment, the article is a roofing surface, for example it may be a roofing shingle, a tile, or a particulate coating. In one embodiment, the article is a container, such as a tank, pipe, or siding, such as a sink or a water pipe. In one embodiment, the article is a floor covering product, such as a concrete surface, a pavement surface, a flooring product, a roadway surface, a parking lot surface, or a sidewalk surface. In one embodiment, the article is a painted article. In one embodiment, the article is a powder coated article. In one embodiment, the article is a vehicle, such as a car, caravan, truck, or van. In one embodiment, the article is a building, such as a home, hotel, office, or factory. In one embodiment, the article is a plastic article. In one embodiment, the article is a textile or leather product.

B. Second part light-stabilized product

In one embodiment of the first aspect, the present invention provides a coated particulate material, wherein:

(ii) the material has an average crystal size greater than 0.40 μm; and

(iii) a coating including one or more oxide materials, wherein the materials are oxides of one or more elements such as Al, Si, Zr, Ce, and P, but the embodiment is not limited thereto. For example, in some embodiments, the oxide material of the coating may also be an oxide of one or more of Ti, Zn, and Sn.

Thus, in one embodiment, the coating comprises one or more oxide materials, wherein the material is an oxide of one or more elements which are:

(b) Group 13-15(IIIA-VA) P-block element selected from Si, Al, P and Sn and/or

(c) A lanthanide series element.

With such products, durability beyond the range achievable using conventional pigment crystal size materials can be achieved. This has advantages in terms of convenience, expense, appearance and durability.

In many exterior paints, carbon black acts as a colorant and is suitable for absorbing harmful ultraviolet radiation and thus improving weatherability. The resulting photoprotective deficiencies must also be addressed when replacing carbon black with alternative black pigments. The present invention is particularly useful to address this deficiency due to its UV absorption and low photocatalytic activity.

The coated particulate material is substantially white. Preferably, the product has a brightness value L (CIE L a b color space) of more than 95, with a value of less than 5 and b value of less than 5. In one embodiment, the product has a brightness value L of greater than 96, such as greater than 97, greater than 98, or greater than 99. a may be less than 4, for example less than 3, in one embodiment. b may be less than 4, such as less than 3, in one embodiment.

The coating is thus selected so as to obtain a product that looks substantially white to the eye. Preferably, any coloured oxide material, for example ceria, included in the coating is present in an amount of 0.5 wt% or less, preferably 0.4 wt% or less, more preferably 0.3 wt% or less, especially 0.2 wt% or less.

In one embodiment, the coated particulate material is provided in a colouring composition comprising:

the coated particulate material is selected from titanium dioxide, doped titanium dioxide and combinations thereof as a NIR scattering particulate material having an average crystal size greater than 0.40 μm and a particle size distribution such that 30% or more of the particles are less than 1 μm; and

one or more non-white colorants; wherein the particulate material and the non-white colorant are dispersed within a carrier.

In particular, in this embodiment, the NIR scattering particulate material (being titanium dioxide, doped titanium dioxide, or a combination thereof) is prepared via a process comprising a milling step. The particles resulting from the milling step may be coated, for example with a hydrated oxide such as silica, alumina or zirconia; such a coating step may result in reduced photocatalytic activity, improved dispersibility, reduced yellowness or better opacity.

For example, the particles may be coated with an inorganic coating at a level of up to 20% wt/wt, for example 0.5 to 20% wt/wt.

In one embodiment, inorganic coatings selected from inorganic oxides may be used. An example of these materials (expressed as their oxides) is Al₂O₃、SiO₂、ZrO₂、CeO₂And P₂O₅。

Accordingly, in one embodiment, the present invention provides a coloring composition comprising:

one or more non-white colorants;

wherein the particulate material and non-white colorant are dispersed within a carrier;

and wherein the coating comprises one or more oxide materials, wherein the material is an oxide of one or more elements which are:

(b) Group 13-15(IIIA-VA) P-block element selected from Si, Al, P and Sn and/or

(c) A lanthanide series element.

In particular, the coating may be selected from Al₂O₃、SiO₂、ZrO₂、CeO₂And P₂O₅。

In an alternative embodiment, the coated particulate material is not provided in a colouring composition comprising:

one or more non-white colorants;

In such embodiments, the coated particulate material may be provided alone, or in any composition that is a combination of the coated particulate material and one or more other components, provided that the composition is not a coloring composition comprising:

one or more non-white colorants;

In a second aspect, the present invention also provides the following

(i) An average crystal size greater than 0.40 μm; and

(b) Group 13-15(IIIA-VA) P-block element selected from Si, Al, P and Sn and/or

(c) Lanthanide series element

The particulate material is preferably substantially white when coated. Preferably, the product has a brightness value L (CIE L a b color space) of more than 95, with a value of less than 5 and b value of less than 5. In one embodiment, the product has a brightness value L of greater than 96, such as greater than 97, greater than 98, or greater than 99. a may be less than 4, for example less than 3, in one embodiment. b may be less than 4, such as less than 3, in one embodiment.

The coating is thus suitably selected so as to obtain a product that looks substantially white to the eye. Preferably, any coloured oxide material, for example ceria, included in the coating is present in an amount of 0.5 wt% or less, preferably 0.4 wt% or less, more preferably 0.3 wt% or less, especially 0.2 wt% or less.

In one embodiment, the use relates to a colouring composition comprising:

as a NIR scattering particulate material selected from titanium dioxide, doped titanium dioxide and combinations thereof, having an average crystal size greater than 0.40 μm and a particle size distribution such that 30% or more of the particles are less than 1 μm; and

one or more non-white colorants;

In one embodiment, the oxide coating is selected from Al₂O₃、SiO₂、ZrO₂、CeO₂And P₂O₅。

Such a coloring composition may be as described above.

In an alternative embodiment, the use does not involve a coloring composition comprising:

one or more non-white colorants;

In such embodiments, the use may relate to the material itself, or the use may relate to the material in any composition that is a combination of the coated particulate material and one or more other components, provided that the composition is not a colouring composition comprising:

The present invention also provides in a third aspect the use of a material according to the first aspect to improve the durability and/or lifetime of a product exposed to sunlight during use.

In a fourth aspect, the invention also provides a product which is exposed to sunlight during use, the product comprising a material according to the first aspect.

US 4125412 describes the preparation of titanium dioxide pigments having excellent chalk resistance, excellent dispersibility and excellent hue retention when applied in paint formulations as follows: these pigments are provided with a dense silica coating, followed by deposition of alumina. However, these conventional titanium dioxide pigment products do not achieve the surprisingly good durability permitted by the present invention, which results from the synergistic combination of large crystal size and coating.

EP 0595471 discloses how to use ultrasound for TiO₂A dense silicon oxide coating is applied.

JP 06107417 describes the coating of acicular TiO with 1 to 30 wt.% of a metal salt₂And then fired to provide a colored product. TiO 2₂The article has physical similarity to asbestos, which attributes its undesirable properties to its high aspect ratio/acicularity characteristics. In the present invention, the particulate material preferably has an aspect ratio of less than 4: 1.

The prior art does not disclose how to improve the durability and/or lifetime of products exposed to sunlight during use.

The product of the invention provides an increased lifetime for objects containing titanium dioxide pigments exposed to solar radiation compared to the prior art. The prior art does not disclose or suggest that the combination of large crystalline titanium dioxide with a coating causes such a reduction in photocatalytic activity.

The combination of large crystalline titanium dioxide with the coating causes a greater reduction in photocatalytic activity than predicted by the known effects of the coating. This synergistic effect is unexpected and provides significant benefits.

As discussed above, in the present invention, the coating comprises one or more oxide materials, wherein the material is an oxide of one or more elements which are:

(b) Group 13-15(IIIA-VA) P-block element selected from Si, Al, P and Sn and/or

(c) A lanthanide series element.

Examples of suitable lanthanides include Ce.

As the skilled artisan will appreciate, the oxide material may be in the form of a mixed oxide, such as a hydroxy hydroxide, or in the form of a hydrated oxide, as well as in the form of an oxide containing only the element plus oxygen.

The coating on the particles may be dense or non-dense. For example, the skilled artisan will appreciate that silica and alumina may be provided as dense or non-dense coatings. A sample of standard rutile titanium dioxide crystals has a thickness of about 7m²Surface area in g. The standard rutile titanium with 3% w/w non-dense coating sample had about 17m²Surface area in g. The standard rutile titanium with 3% w/w dense coating sample had about 6m²/g-10m²Surface area in g.

In one embodiment, two or more coatings comprising oxide materials are used.

They may be used in combination to produce a single layer, or may be used to provide two or more separate layers, each layer having a different composition.

For example, the coating of particles may comprise a layer of silicon oxide, such as a dense silicon oxide layer, and a layer of aluminum oxide.

The particles can be coated with any suitable amount of coating. For example, the particles may be coated with an inorganic coating at a level of up to 20% wt/wt, for example 0.5 to 20% wt/wt. In one embodiment, the particles may be coated at a level of up to 20% wt/wt, such as 0.1 to 20% wt/wt, such as 0.5 to 10% wt/wt, such as 0.5 to 7% wt/wt.

The particulate material for use in the present invention is titanium dioxide or doped titanium dioxide (or a combination thereof) and has an average crystal size greater than 0.40 μm. There may be only a single type of particulate material or there may be two or more different types of particulate material.

In one embodiment, the particulate material is or includes doped titanium dioxide.

The doped titanium dioxide may have 10 wt% or more, preferably 12 wt% or more of TiO₂And (4) content. Preferably, the doped titanium dioxide may have 80 wt% or more, preferably 85 wt% or more of TiO₂And (4) content.

The doped titanium dioxide may be in the rutile or anatase modification or a mixture of anatase and rutile.

In one embodiment, the doped titanium dioxide has a rutile crystal structure. In another embodiment, the doped titanium dioxide has an anatase crystal structure. Anatase and rutile have different strengths; the invention allows for a more durable version of either profile.

For example, it may be 50% or more rutile, such as 60% or more, for example 70% or more, preferably 80% or more, more preferably 90% or more, most preferably 95% or more, such as 99% or more, for example 99.5% or more by weight.

For example, doped titanium dioxide may be doped with dopants such as calcium, magnesium, sodium, aluminum, antimony, phosphorus, and cesium. In one embodiment, the doped titanium dioxide may be doped with a dopant selected from Cr, V, Mn and Al.

The doped titania may include impurities, for example, at a level of up to 10 wt% or less, such as 8 wt% or less, for example 5 wt% or less. These impurities originate from incomplete purification and may, for example, be iron, silicon oxide, niobium oxide or other impurities usually present in titanium dioxide bearing raw materials. In one embodiment, the doped titania may include impurities at levels up to 0.5 wt% or less, such as 0.1 wt% or less, such as 0.01 wt% or less; these impurities may be, for example, Fe, P, Nb or other impurities commonly present in titania bearing feedstocks.

The doped titanium oxide may have a crystal lattice doped with impurities that act as recombination centers for holes and electrons. For example, Cr, Mn and V may all be used as dopants to promote recombination. These impurities are often added in the form of a salt prior to calcination by adding the salt to the precipitated slurry/pulp. Alternatively, the impurities may be allowed to come from the titanium ore in controlled amounts. The amount of dopant used is typically 2-10ppm, as the durability benefits must be balanced against discoloration.

In one embodiment, the particulate material is or includes titanium dioxide.

The titanium dioxide may be prepared by any known method. For example, the so-called "sulfate" route or the so-called "chloride" route, which are two routes in a wide range of commercial applications, may be used. Likewise, a fluoride process, a hydrothermal process, an aerosol process, or a leaching process may be used to produce titanium dioxide.

The titanium dioxide may be in the rutile or anatase crystal form. In one embodiment, the titanium dioxide is 50% or more rutile, such as 60% or more, for example 70% or more, preferably 80% or more, more preferably 90% or more, most preferably 95% or more, for example 99% or more, such as 99.5% or more by weight.

The titanium dioxide may be white or may be coloured. In one embodiment, it may be substantially white; for example, it may have a brightness value L (CIE L a b color space) greater than 95, with a value less than 5 and b value less than 5.

The titanium dioxide may include impurities, for example, at a level of up to 10 wt% or less, such as 8 wt% or less, for example 5 wt% or less. These impurities originate from incomplete purification and may, for example, be iron, silicon oxide, niobium oxide or other impurities usually present in titanium dioxide bearing raw materials. In one embodiment, the titanium dioxide may include a level of impurities of 0.5 wt% or less, such as 0.1 wt% or less, such as 0.01 wt% or less; these impurities may be, for example, iron, phosphorus, niobium oxide or other impurities that are normally present in titanium dioxide bearing raw materials.

Preferably, the titanium dioxide has 90 wt% or more, such as 92 wt% or more, such as 93 wt% or more of TiO₂And (4) content. More preferably, the titanium dioxide has 95 wt% or more, such as 99 wt% or more, such as 99.5 wt% or more TiO₂And (4) content.

The titanium oxide may have a crystal lattice doped with impurities that act as recombination centers for holes and electrons. For example, Cr, Mn and V may all be used as dopants to promote recombination. These impurities are often added in the form of a salt prior to calcination by adding the salt to the precipitated slurry/pulp. Alternatively, the impurities may be allowed to come from the titanium ore in controlled amounts. The amount of dopant used is typically 2-10ppm, as the durability benefits must be balanced against discoloration.

In the present invention, the particulate material preferably has an aspect ratio of less than 4: 1, for example 3: 1 or less, more preferably 2: 1 or less.

In the present invention, the particulate material has an average crystal size of greater than or equal to 0.40 μm. Preferably, the particulate material has an average crystal size greater than or equal to 0.45 μm. Preferably, the average crystal size is greater than or equal to 0.50 μm, such as 0.55 μm or greater, more preferably 0.60 μm or greater, such as 0.70 μm or greater, for example 0.80 μm or greater.

In another embodiment, the particulate material has an average crystal size of greater than 0.40 μm and up to 2.0 μm, such as from 0.45 to 1.8 μm, more preferably from 0.50 to 1.6 μm, such as from 0.60 to 1.4 μm.

Average crystal size photographs obtained by image analysis of polished samples by transmission electron microscopy (e.g. usingKS300 image analyzer). This can be achieved by reference to NIST-derived latex NANOSPHERE with a guaranteed size of 199+/-6nm^TMThe size criteria 3200 validation.

Conventional rutile titanium dioxide pigments have an average crystal size of 0.17-0.29 μm, while conventional anatase titanium dioxide pigments have an average crystal size of 0.10-0.25 μm.

The crystal size is different from the particle size. The particle size depends on the effectiveness of the dispersion of the pigment in the system in which it is used. Particle size is determined by factors such as crystal size and milling techniques, such as dry, wet or combined milling. The average particle size of conventional rutile titanium dioxide pigments is from 0.25 to 0.40 μm, while conventional anatase titanium dioxide pigments have an average particle size of from 0.20 to 0.40. mu.m. Larger particle sizes may result if the technique used is such that the crystals "clump" together.

In the present invention, the particulate material preferably has an average particle size of greater than 0.40 μm as determined by X-ray sedimentation. For example, the average particle size may be greater than 0.40 μm and up to 1.2 μm. Preferably, the average particle size is greater than or equal to 0.45 μm, such as from 0.45 to 1.1 μm, such as from 0.50 to 1.0 μm, more preferably from 0.60 to 1.0. mu.m.

In the present invention, the particulate material preferably has a particle size distribution such that 30% or more of the particles are smaller than 1 μm. In one embodiment, the particulate material has a particle size distribution such that 35% or more of the particles are less than 1 μm, for example 40% or more of the particles are less than 1 μm. In the present application, when referring to a percentage of particles having a given size, this refers to the weight percentage.

As the skilled person will appreciate, the NIR scattering particulate material (being titanium dioxide, doped titanium dioxide or a combination thereof) is prepared via a process comprising a milling step. A preferred grinding step comprises using a mill selected from the group consisting of a fine media mill and a sand mill. In such mills, a grinding media (accelerated by means other than gravity) is used to reduce slurry pigment agglomerates to submicron sizes.

The particles resulting from the milling step are then coated. The particles resulting from the milling step may be coated with a hydrated oxide such as silica, alumina or zirconia.

The coating of the particulate material (being titanium dioxide, doped titanium dioxide, or a combination thereof) may be similar to the coating of conventional pigment materials, as is known in the art. Thus, may include: the material is dispersed in water, after which a suitable coating agent, such as aluminium sulphate, is added. The pH is then adjusted to cause precipitation of the desired hydrated oxide to form a coating on the surface of the material.

In one embodiment, coating may include adding a suitable coating agent, such as aluminum sulfate, to the aqueous slurry of the material to be coated; the pH of the aqueous slurry is then adjusted to cause precipitation of the desired hydrous oxide to form a coating on the surface of the titanium dioxide, doped titanium dioxide, or combinations thereof.

Coating can generally be achieved at acidic pH (e.g., pH about 1-2) or basic pH (e.g., pH about 9.5-12) by adding a suitable salt to the particulate material to neutralize and cause precipitation. The salt may be added first, followed by subsequent adjustment of the pH: or the pH can be adjusted while the salt is added.

After the coating is formed, the material may be washed and dried prior to grinding (e.g., in a fluid energy mill or a micronizer) to isolate particles that have been adhered together by the coating and/or drying steps.

In this final grinding stage, an organic surface treatment, such as a polyol, amine, alkyl phosphonic acid, or silicone derivative, may be applied as desired.

In one embodiment, the particulate material may be treated to selectively remove specific fractions. For example, any particles 5 μm or more in diameter may be removed; in one embodiment, any particles having a diameter of 3 μm or greater may be removed. For example, such particles may be removed by centrifugation.

In the third and fourth aspects, the product exposed to sunlight during use may comprise the coated particulate material in an amount of 0.5 to 70 vol%, such as 1 to 60 vol%, for example 2 to 50 vol%.

The level of coated particulate material in the application may be suitably selected, depending on the intended application.

In the third and fourth aspects, the product which is exposed to sunlight during use may be selected from a plastic product (e.g. a plastic container), an ink, a coating composition (including paint and powder coating compositions), a roofing composition (which may for example be a roofing shingle, a tile or a granular coating) or a floor covering composition (e.g. a pavement product, a flooring product, a driveway surface product, a parking lot surface product or a sidewalk surface product) and a solar reflective product.

In one embodiment, the product is a paint and it may comprise coated particulate material in an amount of from 5 to 50% v/v, for example from 10 to 30% v/v, for example from 15 to 20% v/v.

In one embodiment, the product is a plastic product and it may comprise coated particulate material in an amount of 0.5-70% v/v; for example in a masterbatch, levels as high as 50-70% v/v may be possible or desirable, whereas in a polyethylene bag levels as low as 1-3% v/v may be desirable.

In one embodiment, the product is a coating composition for a roofing or floor covering product and it may comprise coated particulate material in an amount of 1-50% v/v.

In the third and fourth aspects, exposure to the day during useThe product under light may in one embodiment further comprise an organic or inorganic UV absorber or scattering agent. Examples of such UV absorbers/scatterers include Hindered Amine Light Stabilizers (HALS)&Ultrafine TiO 2₂。

The preparation of titanium dioxide or doped titanium dioxide particulate materials having an average crystal size greater than 0.40 μm can be carried out by standard methods for obtaining such materials, modified to apply one or more of the following:

b) calcination is maintained for longer than standard, e.g., 5 hours or more;

e) the level of rutile seeds in the calciner feed pulp is reduced.

A method of obtaining titania or doped titania particulate material having an average crystal size greater than 0.40 μm may comprise:

wherein one or more of the following applies:

b) calcination is maintained for a longer period of time, e.g., 5 hours or more;

e) the level of rutile seed material is reduced in the calciner feed slurry.

The titanium dioxide particulate material is then coated.

The material is suitably ground prior to the coating stage. Milling is surprisingly easy to achieve with the large crystal materials of the present invention. Notably, it was observed that the material broke at practical grinding energies. This may provide additional preparation options and may also facilitate dimensional control.

The coating can be achieved as follows: the material is dispersed in water, after which a suitable coating agent, such as aluminium sulphate, is added. The pH is then adjusted to cause precipitation of the desired hydrated oxide to form a coating on the surface of the material.

After the coating is formed, the material may be washed and dried prior to grinding (e.g., in a fluid energy mill or a micronizer) to isolate particles that have been stuck together by the coating. In this final grinding stage, an organic surface treatment, such as a polyol, amine or silicone derivative, may be applied as desired.

In one embodiment, the titanium dioxide particulate material so obtained may be treated to selectively remove specific size fractions.

In this specification, "average" refers to statistical average, unless otherwise specified. In particular, when referring to average size, this is intended to refer to "geometric volume average size".

The invention will now be further described by means of the following non-limiting examples, which are given for illustrative purposes only.

Examples

In the examples, PVC is pigment volume concentration; pvc ═ polyvinyl chloride

Example 1A Large Crystal TiO₂Preparation of

1.1 methods

Leaching the titaniferous feed material with concentrated sulphuric acid and according to conventional TiO₂The pigment process dissolves the obtained filter cake to form a black sulphate liquid. This "black liquor" is then hydrolyzed according to the Blumenfeld process to precipitate the hydrated titanium dioxide. To this slurry was added 0.3% Blumenfeld nucleic (prepared according to this technique by leaching a portion of the hydrated titanium dioxide described above in concentrated sodium hydroxide solution, followed by reacting the sodium titanate prepared with hydrochloric acid). Further adding 0.05% w/w Al to the pulp₂O₃And 0.2% w/w K₂And O. The feed slurry was then calcined by ramping the temperature, etc., to about 1000 c at a rate of 1 c/min. The precise temperature is chosen to ensure an anatase level of 0.1-3%. Manganese sulfate may optionally be used as a dopant at a concentration of < 0.2% prior to calcination.

The resulting product was characterized as follows: i) an electron micrograph of the ground sample was obtained, and the image was subsequently analyzed using a KS300 image analyzer from Carl Zeiss to obtain a mass average crystal size; and ii) measuring the X-ray diffraction pattern to obtain% rutile.

1.2 results

The average crystal size was found to be 0.79 (with a geometric weight standard deviation of 1.38, measured by transmission electron microscopy followed by image analysis using KS300 from Carl Zeiss). The rutile content was found to be 99%.

Example 1B Large Crystal TiO₂Preparation of

1.1 methods

a) Preparation of starting Material Using Mecklenburg precipitation

The titaniferous feed material is leached with concentrated sulfuric acid and the resulting filter cake is dissolved in dilute acid to produce a solution of titanium sulfate. This titanium sulfate is subsequently hydrolyzed by the deliberate addition of an anatase core ("the Mecklenburg" method) to precipitate hydrous titanium oxide. This hydrous titanium oxide ore slurry was used as a starting material.

b) Formation of large crystal TiO from starting materials₂

The pulp is washed and leached. 0.2% of K₂O and 0.2% Al₂O₃(% wt/wt) addition to the TiO₂In (1). The slurry is then calcined in a rotary kiln. The temperature was increased to 1030 ℃ at a rate of 1 ℃/min. The sample was then held at 1030 ℃ for 30 minutes and then allowed to cool.

c) Characterization of

Characterization of the resulting TiO by visual evaluation of Electron micrographs₂And% rutile is characterized by X-ray diffraction.

1.2 results

Obtained TiO₂With an average crystal size > 0.5 μm, an average particle size > 1 μm and > 99% rutile.

The electron micrograph is shown in figure 1.

Example 1C-Large Crystal TiO₂Preparation of

1.1 methods

a) Preparation of starting Material Using Mecklenburg precipitation

The titaniferous feed material is leached with concentrated sulfuric acid and the resulting filter cake is dissolved in more dilute sulfuric acid to produce a solution of titanium sulfate. This titanium sulfate solution is then heated to precipitate hydrous titanium oxide, which precipitates are nucleated by the addition of fine anatase crystals ("Mecklenburg" method). This hydrous titanium oxide ore slurry was used as a starting material.

b) Formation of large crystal TiO from starting materials₂

The slurry is filtered and washed. Potassium sulfate and aluminum solution were then added to the pulp to obtain 0.2% K₂O and 0.2% Al₂O₃(expressed as being based on TiO)₂In% wt/wt). The slurry is then dried and calcined in a rotary kiln. During calcination, the temperature was increased to 1030 ℃ at a rate of 1 ℃/min. The sample was then held at 1030 ℃ for 30 minutes and then allowed to cool. Manganese sulfate may be used as a dopant prior to calcination.

c) Characterization of

The resulting TiO was characterized as follows₂: i) an electron micrograph of the ground sample was obtained, and the image was subsequently analyzed using a KS300 image analyzer from Carl Zeiss to obtain a mass average crystal size; and ii) measuring the X-ray diffraction pattern to obtain% rutile.

1.2 results

Obtained TiO₂Has a mass average crystal size of > 0.5 μm and a% rutile of > 95%.

Example 2 measurement of reflectance Spectrum

2.1 method

The large crystal rutile sample prepared in example 1B was ball milled into an alkyd paint resin in an amount of 50% wt/wt (20% v/v). After ball milling, the paint was knife coated on a black substrate using a 3K rod. The reflection to black was recorded with a NIR/vis spectrometer equipped with a photosphere.

2.2 results

With conventional TiO being available₂The spectrum of the large crystal rutile shows less reflection in the visible (400-700nm) and more reflection in the NIR (700-2500nm) compared to pigments.

Shows the spectra of the sample of example 1B, along with conventional TiO₂(TR81 pigment-commercially available from Huntsman Pigments Division) and a spectrum of a black substrate are shown in fig. 2.

Example 3A-coated Large Crystal TiO₂Preparation of

The TiO of example 1A was first dry milled using a Raymond mill₂. It was then slurried to 350gpl and ground in a fine media mill containing Ottawa sand for 30 minutes. The sand is then separated from the slurry.

The resulting slurry was then coated with dense silica and alumina (particle size 0.87: 1.44 standard deviation by geometric weight as measured by Brookhaven X-ray disk centrifuge). In this respect, the TiO is mixed with₂The slurry was introduced into a stirred tank, the temperature was raised to 75 ℃ and the pH was adjusted to 10.5. 1.0% of silicon oxide (w/w based on TiO)₂) Added as sodium silicate over 30 minutes and mixed for 30 minutes. Sulfuric acid was added over 60 minutes to bring the pH to 8.8, and then over 35 minutes to bring the pH to 1.3. Next, 0.6% alumina was added from caustic sodium aluminate over 25 minutes to bring the pH to 10.25: whereupon it was mixed for 20 minutes. Finally, the pH was adjusted to 6.5 by adding sulfuric acid. The coated product is then washed and dried, followed by fluid energy milling.

This IR reflective product was characterized as follows:

particle size-the product is subjected to high shear mixing in the presence of a suitable dispersant to disperse the particles without comminution. Particle size distribution was measured using a Brookhaven XDC X-ray disk centrifuge. The average particle size and particle size geometric weight standard deviation are reported.

Crystal size-a small sample of the product is dispersed and sheared according to any suitable grinding technique. Dropping the paste onto a microscopy lining paper and evaporating itJEM 1200EX transmission electron microscope. The mean crystal size and the crystal size geometric weight standard deviation were evaluated using the Carl Zeiss KS300 image analysis software.

The samples were subjected to accelerated weathering and a durability ratio of 0.68 was measured using the method described in example 7.

Example 3B-coated Large Crystal TiO₂Preparation of

Method

The TiO of example 1C was first dry milled using a Raymond mill₂. It was then slurried to 350gpl and ground in a fine media mill containing Ottawa sand for 30 minutes. The sand is then separated from the slurry.

The resulting slurry is then coated with dense silica and alumina. In this connection, TiO is added₂The slurry was introduced into a stirred tank and the pH was adjusted to 10.5. 3.0% of silicon oxide (w/w based on TiO)₂) Added as sodium silicate over 30 minutes and mixed for 30 minutes. Sulfuric acid was added over 60 minutes to bring the pH to 8.8, and then over 35 minutes to bring the pH to 1.3. Next, 2.0% alumina was added from caustic sodium aluminate over 25 minutes to bring the pH to 10.25: whereupon it was mixed for 20 minutes. Finally, the pH was adjusted to 6.5 by adding sulfuric acid.

The coated product is then washed and dried, followed by fluid energy milling.

Example 4A Large Crystal TiO₂Application in black paint

The product of example 1A was evaluated in an acrylic paint system.

Method

Wetting Using an acrylic resin&Dispersing additives, solvents and colorants to prepare a color concentrate. The colorant may be carbon black or a NIR transparent black colorant (e.g., a black colorant)paliogen black stain, S0084).

Coloring agent concentrate composition	％
		60% acrylic resin (40% solvent)	78
Solvent(s)	4
		Moistening&Dispersing additive	9
Coloring agent	9

This dyeing concentrate was milled with steel microspheres. Thus, a dyed acrylic resin solution was prepared.

Dyed acrylic resin solution component	％
		60% acrylic resin (40% solvent)	85
Stain concentrates	15

The pigment was added to a portion of the dyed acrylic resin solution in a test to produce a millbase. The amount of pigment was varied to produce different pigment volume concentrations (pvc). This dyed acrylic millbase was then milled for 2 minutes and then let down with a greater amount of dyed acrylic solution.

This test paint was then applied to the opaque card using a wire-wound applicator; the applicator gauge measures the nominal wet film thickness. The solvent was allowed to evaporate and the panel was then baked at 105 ℃ for 30 minutes.

The reflectance spectra were measured using a UV/vis/NIR spectrophotometer with a light collection sphere and a wavelength range of 400-2600 nm. The total solar reflectance was calculated from this data according to the method described in ASTM E903. From this data, L, a & b under the light source D65 were also calculated.

The results are shown in fig. 3 and 4.

The following results were obtained for the example in FIG. 4 by replacing the value at L x 40 in the Lawrence Berkeley SRI calculator (reference: ASTM1980 specification)

	TSR	SRI	Surface temperature
				Conventional TiO₂	7.8	4	354.4K/178°F
TiO₂(present invention)	10.0	6	353.2K/176°F

Example 4B preparation of the paint

To prepare a pigmented paint, the large crystal rutile sample prepared in example 1B was ball milled into an alkyd paint resin in an amount of about 15% v/v and a non-white colorant was added in an amount of about 1% v/v.

Non-white colorants that may be used are:

(i) chrome titanate yellow, (ii) nickel titanate yellow, (iii) perylene black, (iv) synthetic red iron oxide, (v) copper phthalocyanine and (vi) quinacridone red.

Example 4C preparation of the paint

Use of the coated TiO from example 3B₂Preparation ofImproved paint products. In this regard, the coated large crystal rutile sample prepared in example 3B was incorporated into an alkyd melamine formaldehyde based paint in an amount of about 23% v/v.

In Atlas C165aDurability was measured in the instrument and evaluated as mass loss over 2000 hours of exposure.

Example 5-benefits in PVCu when Complex inorganic coloring pigments are used

PVC sheets were prepared with a range of titanium dioxide & pigment green 17 concentrations such that the total pigment volume concentration remained constant.

Initial PVC formulation:

components	g/100g resin
		PVC resin	100
Ca/Zn stabilizer	5
		Acrylic impact modifiers	6
Acrylic acid series processing aid	1.5
		Calcium carbonate	6
TiO₂	5

TiO₂PG17 to maintain a constant pigment volume:

TiO₂/(TiO₂+PG17)	100％	75％	50％	25％	0％
						TiO₂ ^*(g)	6.30	4.73	3.15	1.58	0.00
hematite (g)	0.00	2.03	4.08	6.15	8.19

For two types of TiO₂Was performed as follows: conventional pigmentary TiO₂And the material obtained using the method of example 1A. This material used had an average crystal size of 0.97 microns and an average particle size of 0.85 microns (which had been milled through its crystal size).

Pvc sheets were prepared as follows:

the dry blend was prepared using a crypto-peerless type mixer.

A j.r.dare two-roll mill (155 ℃ front roll &150 ℃ rear roll) was used to make pvc.

The resulting pvc was preheated to 165 ℃ for 3 minutes and then 15te/in²Pressing for 2 minutes.

The reflectance spectra were measured using a UV/vis/NIR spectrophotometer with a light collection sphere and a wavelength range of 400-2600 nm. The total solar reflectance was calculated from this data according to the method described in ASTM E903. From this data, L, a & b under the light source D65 were also calculated. The results are shown in FIGS. 5 and 6.

This figure demonstrates that the titanium oxide of the present invention exhibits a lower visible hue reduction relative to conventional titanium dioxide, thereby enabling higher concentrations to be used up to a given L. As a result, higher concentrations can be used, resulting in improved solar reflectance at a given L.

Using the values at L40 in the Lawrence Berkeley SRI calculator, the following results were obtained for the example in FIG. 6 (reference: ASTM1980 specification)

	L^*	TiO₂Black pigment	TSR	SRI	Surface temperature
						Conventional TiO₂	40	50∶50 v∶v	24.7	25	346.1K/163°F
TiO₂(present invention)	40	70∶30 v∶v	28.5	30	344.3K/160°F

Example 6 benefits in carbon Black dyed PVC-u

PVC sheets were prepared having a range of volume ratios (titanium dioxide: carbon black). TiO per hundred parts resin₂The parts were fixed at 5% and the carbon black was changed to obtain 0.100%, 0.050%、0.010％&0.005% of the total amount of the polymer.

For two types of TiO₂Was performed as follows: conventional pigmentary TiO₂And the material obtained by the method of example 1A.

Initial PVC formulation:

components	phr (parts per 100 parts resin)
		PVC resin	100
Ca/Zn stabilizer	5
		Acrylic impact modifiers	6
Acrylic acid series processing aid	1.5
		TiO₂	5

Dry blends were prepared using a crypto-peerless type mixer.

J.R.Dare two-roll mill (155 ℃ front roll)&150 ℃ post roll) was used to make PVC. The resulting PVC was preheated to 165 ℃ for 3 minutes and then at 15te/in²Pressing for 2 minutes.

The results are shown in FIG. 7.

	L^*	TSR	SRI	Surface temperature
					Conventional TiO₂	60	23.1	23	346.9K/165°F
TiO₂(present invention)	60	30.0	32	343.5K/159°F

Example 7 durability benefits in baked alkyd Melamine Formaldehyde paints

The following millbases were ball milled for 16 hours.

Millbase component	Quality (g)
		TiO₂Pigment (I)	68.0
15% alkyd resin	28.0
		8mm glass microspheres	170

The millbase was stabilized by adding 15g of a 60% commercial alkyd resin and tumbled for 30 minutes. After tumbling, further addition of: 24.3g of a 60% alkyd resin and 15.3g of a 60% commercial melamine-formaldehyde resin. The resulting paint was tumbled for an additional 30 minutes and then decanted and degassed for 15 minutes.

The degreased steel panels were weighed and the paint in the test was spin coated onto the front of the test panels. The paint was allowed to flash for at least 60 minutes and then dried at 150 ℃ for 30 minutes. Sufficient paint is applied to achieve a dry film thickness of at least 40 μm. The panel was then reweighed.

In Atlas Ci65aThe panels were exposed to the instrument for a total of 3000 hours, removed every 250 hours for measurement, and then returned to the weatherometer for further exposure.

For the test pigments, the corresponding points for the standard pigments are plotted against the mass loss at each measurement time. The slope, which is the endurance ratio DR, is determined using a minimum square fit. Lower DR is preferred: indicating excellent weatherability.

The results are shown in figure 8 and in the table below.

Commercial conventional TiO₂Grade

Claims

1. A coloring composition comprising:

a NIR scattering particulate material selected from titanium dioxide, doped titanium dioxide and combinations thereof, the material having an average crystal size greater than 0.40 μm and a particle size distribution such that 30% or more of the particles are less than 1 μm;

one or more non-white colorants;

2. The composition of claim 1, wherein the NIR scattering particulate material is coated at a level of up to 20% wt/wt with an inorganic coating selected from inorganic oxides, hydroxides and combinations thereof.

3. The composition of claim 1 or claim 2, wherein the NIR scattering particulate material has an average crystal size of greater than or equal to 0.50 μm.

4. The composition of claim 3, wherein the NIR scattering particulate material has an average crystal size of greater than or equal to 0.60 μm.

5. The composition of claim 4, wherein the NIR scattering particulate material has an average crystal size of from 0.70 μm to 1.20 μm.

6. The composition of any of the preceding claims, wherein the composition comprises NIR scattering particulate material in an amount of 0.5 to 70 vol%.

7. The composition of any of the preceding claims wherein the colorant is selected from the group consisting of chromium titanate yellow, nickel titanate yellow, synthetic red iron oxide, perylene black, copper phthalocyanine, and quinacridone red.

8. The composition of any of the preceding claims, wherein the composition comprises a non-white colorant in an amount of 0.1 to 20 vol%.

9. The composition of any of the preceding claims, wherein the coloring composition is a plastic composition; painting; powder coating; printing ink; a textile component; a textile treatment composition; a leather treatment composition; a roofing product composition or a floor covering product composition.

10. Use of a composition according to any one of claims 1 to 9 to provide a single coat covering having solar reflectance and a non-white colour.

11. Use of a composition according to any one of claims 1 to 9 for the preparation of an article having solar reflectance and a non-white colour.

Use of a NIR scattering particulate material selected from titanium dioxide, doped titanium dioxide and combinations thereof, having an average crystal size greater than 0.40 μm and having a particle size distribution such that 30% or more of the particles are less than 1 μm, to increase the level of solar reflection of a dark or strongly coloured composition.

13. Use according to claim 12, wherein the NIR scattering particulate material is used to obtain a total solar reflectance of 20% or more for the dark or strongly coloured composition.

14. An article comprising the composition of any of claims 1-9.

15. The article of claim 14 which is a roofing surface; a container; a painted article; a vehicle; a building; a textile; a leather product; a concrete surface; a pavement; a flooring product; a lane surface; a parking lot surface; a sidewalk surface; powder coated articles or plastic articles.

16. A coated particulate material, wherein:

(ii) the material has an average crystal size greater than 0.40 μm; and

(b) Group 13-15(IIIA-VA) P-block element selected from Si, Al, P and Sn and/or

(c) A lanthanide series element,

wherein the coated product is substantially white.

17. The material of claim 16, wherein the coated particulate material is provided in a coloring composition comprising:

the coated particulate material is selected from titanium dioxide, doped titanium dioxide and combinations thereof as a NIR scattering particulate material having an average crystal size greater than 0.4 μm and a particle size distribution such that 30% or more of the particles are less than 1 μm; and

one or more non-white colorants;

18. The material of claim 17, wherein the coating is selected from Al₂O₃、SiO₂、ZrO₂、CeO₂And P₂O₅An oxide material of (a).

19. The material of claim 16, wherein the coated particulate material is not provided in a coloring composition comprising:

one or more non-white colorants;

20. The following were used:

(i) an average crystal size greater than 0.40 μm; and

(b) Group 13-15(IIIA-VA) P-block element selected from Si, Al, P and Sn and/or

(c) Lanthanide series element

21. Use of a material according to any of claims 16-19 to improve the durability and/or lifetime of a product exposed to sunlight during use.

22. A product which is exposed to sunlight during use, the product comprising a material according to any one of claims 16-19.

23. The use according to claim 21 or the product according to claim 22, wherein the product exposed to sunlight during use is selected from the group consisting of plastic products, inks, paints and other coating compositions, roofing compositions, floor covering compositions and solar reflective products.

24. The product or use of any of claims 21-23, wherein the product that is exposed to sunlight during use further comprises an organic or inorganic UV absorber or scattering agent.

25. The product or use of any of claims 16-24, wherein two or more coatings comprising oxide materials are used.

26. The product or use of any of claims 16-25, wherein the coating of particles comprises a layer comprising an oxide of Si and a layer comprising an oxide of Al.

27. The product or use of any of claims 16-26, wherein the particulate material has an average crystal size of greater than or equal to 0.50 μ ι η.

28. The product or use of claim 27, wherein the particulate material has an average crystal size of 0.50 to 2 μm.

29. The product or use according to any one of claims 16 to 28, wherein the product has a brightness value L, a value a less than 5 and b value less than 5 of greater than 95.

30. The product or use of any of claims 16 to 29, wherein any coloured oxide material included in the particulate material is present in an amount of 0.5 wt% or less.

31. The product or use of any one of claims 16 to 30 wherein the particulate material has an aspect ratio of less than 4: 1.