Coated particles and methods of making and using the same

Abstract

To provide matting agents that are suitable for use in aqueous coating system and in the final coating have improved chemical resistance, improved thermal stress resistance, improved weather resistance, and / or improved film clarity together with good matting effect, and a method for preparing matting agents.SOLUTION: There is provided a matting agent comprising: silica particles having a particle surface; and greater than 30.0 weight percent (wt.%), based on a total weight of the silica particles, of (i) one or more waxes, (ii) one or more polymers, or (iii) any combination of (i) and (ii) applied on the particle surface.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an improved silica-based matting agent. In one aspect, the present invention relates to an improved silica matting agent for use in water-based coating systems. In another aspect, the present invention relates to a silica matting agent comprising particulate silica coated with a wax or organic polymer, water-based coating compositions containing the matting agent, and methods of making and using the compositions. [Background technology]

[0002] Silica-based matting agents are widely used in coating and painting formulations to reduce the gloss of the coated film. In solvent-based coatings or 100% solid UV-cured formulations, a large amount of silica is required to effectively reduce gloss and matte. On the other hand, high concentrations of hydrophilic silica can cause changes in the rheological properties of solvent-based lacquers and often have problems with dispersion and settling. To solve these problems, the prior art usually performs surface treatment on the particulate silica to make its surface hydrophobic, thereby increasing its compatibility with the solvent system and organic matter in the formulation. For this purpose, silica coated with wax and / or polymer has often been used.

[0003] U.S. Patent No. 6,039,798 discloses a wax-coated silica matting agent, the silica being at least 1.5 cm 3 / g pore volume, preferably at least 1.8 cm 3 The wax coating is present in the range of 6% to 15% by weight of the matting agent and includes a synthetic polyethylene wax.

[0004] EP 0759959 discloses a wax-coated silica matting agent characterized in that the silica is an amorphous silica having a pore size distribution in which 90% of the pores have a diameter greater than 15 nanometers and less than 20% of the pore volume is in pores having a pore diameter between 10 and 30 nanometers, the wax coating being present in the range of about 2% to about 15% by weight of the matting agent and comprising a hard microcrystalline wax, a plasticized microcrystalline wax, a synthetic polyethylene wax, or a mixture thereof.

[0005] US Patent Application Publication No. 20050065268 discloses that the silica particles in the silica matting agent comprise particulate amorphous silica that has been treated with a hydrophilic polyolefin wax.

[0006] US Patent No. 6,921,781 discloses coating at least a portion of the surface of at least one silica particle with at least one wax, the coating being carried out in at least one gas at a temperature above the melting point of the wax and below the decomposition temperature of the wax, the wax content being defined as 2-15% by weight of the silica content.

[0007] U.S. Patent No. 7,303,624 discloses that structurally coated silica can be prepared by spraying and mixing pyrogenic silica with water and a coating agent in a suitable mixing vessel, followed by grinding to further condition the product.

[0008] U.S. Pat. No. 8,926,748 discloses a matting agent useful for preparing a matte coating comprising an inorganic oxide particulate and a wax coated on the inorganic oxide particulate, the wax having a crystallinity of about 50% or more, the wax being capable of forming a matte coating. It is present in an amount ranging from 15% to 30% by weight based on the total weight of the eraser.

[0009] WO 1999051692 discloses an invention relating to a matting agent based on silicon dioxide, in which the silicon dioxide particles have a particle size of 2.5-20 μm and a moisture content of 0-65% by weight, based on the matting agent, and are coated with 0.2-10% by weight of a urea urethane derivative or a mixture of urea urethane derivatives.

[0010] Currently, solvent-based coating compositions are undesirable due to environmental concerns as well as safety and health concerns. Government regulations are driving the reduction and elimination of volatile organic compounds (VOCs) in paint or coating formulations, encouraging the use of coatings that are largely more water-based.

[0011] Various types of matting agents are used in water-based formulations, including silica matting agents, organic matting agents, and blends of the two.

[0012] Silica-based matting agents such as Acematt® TS100, Syloid® C807, etc., have very high matting effect and transparency of the coating in the water-based formulation, but tend to have poorer chemical resistance and weather resistance than usual, often turning opaque or cloudy when exposed to chemicals or weather conditions change. Silica-based matting agents also tend to have poor resistance to thermal stress when exposed to sudden temperature changes. Adhesion failure at the interface of the matting agent and latex, which has the effect of scattering light and is magnified by the particle shrinkage of the matting agent during drying, causing cracks, as well as adhesion failure caused by stress due to the expansion (and then contraction) of the coating while it is wet and drying, can be the cause of disadvantages for silica matting agents in water-based coating formulations. All of these disadvantages are undesirable in coating applications on wood substrates.

[0013] Purely organic organic matting agents are also used. For example, urea formaldehyde resin-based matting agents such as Deuteron® MK and Ceraflour® 920 are known. However, all matting agents have environmental concerns because they can potentially release residual starting materials such as toxic formaldehyde. A modified and micronized polyethylene-based matting agent, Ceraflour® 929, is also available. However, this product has poor matting effect when compared with silica-based matting agents in coating formulations. Organic matting agents are also known to have poor coating transparency when compared with pure silica-based matting agents. This is probably because silica-based matting agents have a reflectance close to that of other components (e.g., binder) in the coated film, while the reflectance difference between the organic matting agents and such components is large. In addition, organic matting agents are usually difficult to manufacture and more expensive.

[0014] Blends of silica-based and organic matting agents have also been used in waterborne systems to balance the required coating film properties, however, this creates additional complexity in an already complex paint or coating formulation system.

[0015] Therefore, there remains a need for a simple solution to develop matting agents that are (i) suitable for use in aqueous coating systems and (ii) provide one or more desirable properties, such as improved chemical resistance, improved thermal stress resistance, improved weatherability, and / or improved film transparency, in the final coating, combined with a good matting effect. Summary of the Invention

[0016] The present invention relates to improved silica-based matting agents that are useful in aqueous coating compositions, as well as The present invention addresses the above-mentioned need in the art by discovering a method for preparing and using the composition. The aqueous composition of the present invention provides exceptional properties to the coated surface of a wood-based substrate. For example, unexpectedly, the coating composition of the present invention can be used to provide a coated film on a wood substrate surface having improved chemical resistance, improved thermal stress resistance, improved weather resistance, and / or improved film clarity.

[0017] The present invention therefore provides an improved silica-based matting agent comprising silica particles having a specific amount of at least one component selected from (i) one or more waxes, (ii) one or more polymers, or (iii) any combination of (i) and (ii) on the surface of the particle.

[0018] It has been unexpectedly found that when increasing amounts of (i) or (ii) or (iii) are used to coat silica particles, certain properties (e.g., chemical resistance) are increased. In a desirable embodiment, the improved silica-based matting agent comprises greater than 30 weight percent (wt%) of at least one of components (i)-(iii). In another embodiment of the present invention, the silica-based matting agent comprises at least 40 weight percent (wt%) of at least one of components (i)-(iii).

[0019] In some exemplary embodiments, the aqueous coating composition comprises a coated silica particle having a particle surface, which is about 40.0% to about 50.0% by weight (or more) of one or more waxes (e.g., polyethylene wax) on the particle surface, based on the total weight of the coated particle. In other exemplary embodiments, the aqueous composition of the present invention comprises a porous silica particle having a particle surface, which is about 45.0% to about 50.0% by weight (or more) of one or more polymers (e.g., polydiene or vulcanized polydiene, etc.) on the particle surface, based on the total weight of the coated particle.

[0020] The present invention also provides aqueous coating compositions and formulations that include the improved silica-based matting agent of the present invention. In some exemplary embodiments, the coating compositions that include the coated silica particles of the present invention have (a) a coating transparency ΔL of less than 7.0 units. * (b) ΔL of water damage (24 hr) less than 5.0 units * (c) ΔL of 50 / 50 water / ethanol injury (1 hr) less than 8.0 units * (d) ΔL of 50 / 50 water / ethanol injury (4 hr) less than 16.0 units * 0.01 to 0.05, all of which are measured using a handheld Spectro-Guide 45 / 0 colorimeter and the methods described herein. In some desirable embodiments, the aqueous coating composition provides a coating composition having (a) a ΔL of film transparency of less than 7.0 units. * (b) ΔL of water damage (24 hr) less than 5.0 units * (c) ΔL of 50 / 50 water / ethanol injury (1 hr) less than 8.0 units * (d) ΔL of 50 / 50 water / ethanol injury (4 hr) less than 16.0 units * All of these are measured using a handheld Spectro-Guide 45 / 0 colorimeter and the methods described herein.

[0021] The present invention further relates to a method for making the coated silica-based matting agent and a method for preparing an aqueous coating composition comprising the matting agent of the present invention. In an exemplary embodiment, the present invention also relates to a method for coating a substrate with the mentioned aqueous coating composition. In a preferred embodiment, the substrate is a wood substrate.

[0022] In other embodiments, methods of using the coated particles described herein can be used to improve the chemical resistance, thermal stress resistance, and / or chemical resistance of a coating composition applied onto a wood substrate (e.g., a wood substrate). The present invention includes a method for improving weatherability, clarity of a coating, or any combination thereof. The method includes incorporating the coated particles described herein into a coating composition prior to application of the coating composition onto a substrate. Unexpectedly, the coating compositions described herein provide improved protection for a given wood substrate when compared to known liquid coating compositions as measured using a colorimeter (e.g., a handheld Spectro-Guide 45 / 0 colorimeter).

[0023] The present invention still further relates to a substrate coated with (i) the coated particles described herein, or (ii) a liquid composition containing the coated particles described herein. In some exemplary embodiments, the substrate comprises a wood substrate coated with (i) the coated particles described herein, or (ii) a liquid composition containing the coated particles described herein.

[0024] These and other features and advantages of the present invention will become apparent after consideration of the following detailed description of the disclosed embodiments and the appended claims. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] To promote an understanding of the principles of the invention, a description of specific embodiments of the invention follows, and specific language is used to describe the specific embodiments. It is to be understood, however, that no limitation of the scope of the invention is intended by the use of specific language. Alterations, further modifications, and further applications of such principles of the invention as contemplated are generally contemplated as would occur to one skilled in the art to which the invention pertains.

[0026] It should be noted that as used in this specification and the appended claims, the singular forms "a," "and," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, a reference to "an oxide" includes a plurality of such oxides, a reference to "an oxide" includes a reference to one or more oxides and equivalents thereof known to those skilled in the art, and so forth.

[0027] For example, "about" used in describing embodiments of the present disclosure to modify amounts, concentrations, volumes, process temperatures, process times, recovery or yield, flow rates, and similar values ​​and ranges of ingredients in the coated particles and / or compositions refers to variations in numerical quantities that may occur, for example, through typical measuring and handling procedures, through inadvertent errors in these procedures, through differences in ingredients used to carry out these methods, and to allow for approximations. The term "about" also encompasses amounts that vary with time in formulations having a particular initial concentration or mixture, as well as amounts that vary with mixing or processing of formulations having a particular initial concentration or mixture. Whether or not modified by the term "about," the appended claims include the equivalent of the amount.

[0028] The present invention relates to an improved silica-based matting agent comprising silica particles having a particle surface and (i) one or more waxes, (ii) one or more polymers, or (iii) any combination of (i) and (ii) coated on the particle surface in an amount of more than 30.0 weight percent (wt%) based on the total weight of the coated particle. Typically, (i) one or more waxes, (ii) one or more polymers, or any combination of (iii) (i) and (ii) are present on the particle surface in an amount of up to about 40.0 wt% based on the total weight of the coated particle, but the coated particles of the present invention may contain any amount of (i) one or more waxes, (ii) one or more polymers, or any combination of (iii) (i) and (ii) in an amount of up to about 50.0 wt% (or more) based on the total weight of the coated particle. In some exemplary embodiments, the coated particles have a coating content of more than 30.0 wt% to about 100 wt% based on the total weight of the coated particle. 50.0% by weight (or any value greater than 30.0% and up to 50.0% in increments of 0.1% by weight, e.g., about 35.1% by weight, or any range of values ​​in increments of 0.1% by weight, e.g., about 30.3% to about 37.8% by weight, from 30.0% to 50.0% by weight) of (i) one or more waxes, (ii) one or more polymers, or (iii) any combination of (i) and (ii) on the particle surface. In some exemplary embodiments, the coated particle comprises greater than about 40.0% to about 50.0% by weight (or any value between 40.0 and 50.0% by weight in increments of 0.1% by weight, e.g., about 40.1% by weight, or any range of values ​​between 40.0 and 50.0% by weight in increments of 0.1% by weight, e.g., about 40.3 to about 47.8% by weight) of (i) one or more waxes, (ii) one or more polymers, or (iii) any combination of (i) and (ii) on the particle surface, based on the total weight of the coated particle.

[0029] Suitable particulate silicas useful for preparing the matting agent of the present invention include, but are not limited to, silica gel, precipitated silica, fumed silica, colloidal silica.Suitable silicas also include, but are not limited to, ordered mesoporous silicas, which are prepared via organic templates (e.g. surfactants) during the formation of silica particles, and then the organics are burned off by pyrolysis at high temperatures.Particularly preferred silica particles include silica gel or precipitated silica particles.

[0030] Commercially available porous silica particles suitable for use in the present invention are available from W. R. Grace (Columbia, MD) under the trade name SYLOID® and include, but are not limited to, porous inorganic particles such as SYLOID® C807 silica gel particles and SYLOID® MX106 precipitated silica particles.

[0031] In preferred embodiments, the silica particles comprise silica having a purity of at least about 93.0 wt.% SiO2, or at least about 93.5 wt.% SiO2, at least about 94.0 wt.% SiO2, at least about 95.0 wt.% SiO2, at least about 96.0 wt.% SiO2, at least about 97.0 wt.% SiO2, or at least about 98.0 wt.% SiO2, up to 100 wt.% SiO2, based on the total weight of the particle.

[0032] Silica particles can have a variety of different symmetrical, asymmetrical or irregular shapes, including chain-like, rod-like or clapper-like shapes. Particles can have different structures, including amorphous or crystalline. In a preferred embodiment, the silica particles are amorphous. Particles can include mixtures of particles that can be the same except for different surface treatments, or have different compositions, sizes, shapes or physical structures. When smaller particles aggregate to form larger particles, the porosity of the particles can be intra- or inter-particle.

[0033] As used herein, the term "crystalline" refers to a solid material in which the constituent atoms, molecules, or ions are arranged in an orderly pattern extending in all three directions, as can be measured by X-ray diffraction or differential scanning calorimetry. As used herein, the term "amorphous" refers to a solid material in which the constituent atoms, molecules, or ions are arranged in a random, unordered pattern extending in all three directions, as can be measured by X-ray diffraction or differential scanning calorimetry.

[0034] As used herein, the term "BET particle surface area" is defined to mean the particle surface area as measured by the Brunauer Emmet Teller (BET) nitrogen adsorption method.

[0035] As used herein, the phrase "total pore volume" is measured using Barrett-Joyner-Halenda (BJH) nitrogen porosimetry as described in DIN 66134. It refers to the average pore volume of a plurality of particles.

[0036] As used herein, the phrase "particle size" refers to the median particle size (D50, which is the volume distribution of 50 volume percent of particles smaller than this number and 50 volume percent of particles larger than this number) measured by dynamic light scattering when the particles are suspended in water or in an organic solvent such as acetone or ethanol.

[0037] The porous silica particles used to form the matting agent of the present invention may have a total pore volume of at least 0.30 cc / g, about 0.30 cc / gm to about 2.20 cc / gm (or any value greater than 0.40 cc / gm to 2.20 cc / gm (inclusive) in 0.01 cc / gm increments (e.g., 0.62 cc / gm), or any value in 0.01 cc / gm increments greater than 0.40 cc / gm to 2.20 cc / gm (inclusive) in 0.01 cc / gm increments (e.g., about 1.50 cc / gm to about 2.20 cc / gm)). Typically, the porous silica particles used to form the matting agent of the present invention have a total pore volume of about 1.8 cc / gm to about 2.00 cc / gm, as measured by the BJH method.

[0038] The porous silica particles used to form the matting agent of the present invention have a particle size of at least about 100 mm. 2 / g~maximum 1500m 2 / g (or 1.0m 2 / g for 100m 2 / g and up to 1500m 2 / g (inclusive) (e.g. 453m 2 / g) or 1.0m 2 / g for 100m 2 / g+~maximum 1500m 2 / g (inclusive) (e.g., about 400m 2 / g ~ approx. 444m 2 Typically, the porous silica particles also have a BET particle surface area of ​​at least about 100 m 2 / g~maximum 900m 2 / g BET particle surface area.

[0039] The uncoated silica particles of the present invention typically have an average particle size of about 1.0 microns (μm) to about 50 μm (or any value from 1.0 μm inclusive up to about 50 μm (e.g., 45.0 μm) in increments of 0.1 μm, or any range of values ​​from 1.0 μm inclusive up to about 50 μm (e.g., about 3.2 μm to about 50.1 μm) in increments of 0.1 μm). However, it should be understood that the coated particles of the present invention can have any average particle size depending on the use of the coated particles. In some embodiments, the coated particles of the present invention have an average particle size of about 3.0 μm to about 12.0 μm.

[0040] The matting agent of the present invention may include one or more waxes coated on the particle surface and in the pores of the porous silica particles. When wax is present, the one or more waxes may include, but are not limited to, hydrocarbon waxes (i.e., those containing relatively long alkyl chains, such as alkyl chains having 20 or more carbon atoms therein, with or without one or more various functional groups, such as fatty acids, primary and secondary long chain alcohols, unsaturated bonds, aromatic hydrocarbons, amides, ketones and aldehydes), paraffin waxes (i.e., those from 20 to 40 carbon atoms without additional functional groups), polyethylene waxes, polypropylene waxes, vegetable waxes such as carnauba wax (i.e., Brazil wax), animal waxes such as beeswax, or any combination thereof.

[0041] Commercially available waxes suitable for use in the present invention include waxes available under the tradenames Hi-WAX™ or EXCEREX™ waxes from Mitsui Chemicals, LLC (Osaka, Japan), waxes available under the tradename RHEOLUB® waxes from Honeywell Performance Additives (Morristown, NJ), and waxes available under the tradename Polarwachs® waxes from TH.C. TROMM GmbH (Columbia, CA). Examples of suitable waxes include, but are not limited to, waxes available from Schweizerhofen, Germany.

[0042] In some embodiments, the matting agent comprises silica particles coated with a polyethylene wax, a polypropylene wax, or a combination thereof. In some desirable embodiments, the coating on the silica particles comprises a polyethylene wax having an average molecular weight of at least 2000. Such relatively high molecular weight polyethylene waxes are commercially available from TH.C.TROMM GmbH (Cologne, Germany) under the trade name Polarwachs® wax.

[0043] When waxes are present, the one or more waxes are typically present in an amount greater than 30% by weight based on the total weight of the matting agent. Preferably, the one or more waxes are present in an amount ranging from about 31.0% to about 50.0% by weight (or any value between 31.0% and 50.0% by weight in 0.1% increments (e.g., about 35.1% by weight), or any value between 31.0% and 50.0% by weight in 0.1% increments (e.g., about 31.3% to about 37.8% by weight) based on the total weight of the matting agent. In some embodiments, the one or more waxes are present in an amount ranging from about 40.0% to about 50.0% by weight (or any value between 40.0% and 50.0% by weight in increments of 0.1% by weight, such as about 45.1% by weight, or any value between 40.0% and 50.0% by weight in increments of 0.1% by weight, such as about 40.3% to about 47.8% by weight) based on the total weight of the matting agent.

[0044] In another embodiment of the present invention, the matting agent of the present invention can comprise one or more polymers on the particle surface and in the pores of the porous silica particle, alone or in combination with one or more waxes mentioned above.When polymers are present, the one or more polymers can comprise, but are not limited to, one or more polymers comprising polydiene (e.g., polyisoprene, polybutadiene, or combinations thereof), vulcanized polydiene, polyacrylamide, polyvinylpolypyrrolidone, cellulose acetate butyrate, or any combinations thereof.In some desirable embodiments, the one or more polymers comprise polydiene, vulcanized polydiene, or any combinations thereof.

[0045] Commercially available polymers suitable for use in the present invention include, but are not limited to, the polymer available from Kuraray Co., LTD under the trade name KL-10 liquid rubber polymer (ie, polyisoprene).

[0046] When a polymer is present, the one or more polymers are typically present in an amount of more than 30% by weight based on the total weight of the matting agent. Preferably, the amount of the one or more polymers is in the range of about 31.0% by weight to about 50.0% by weight (or any value between 31.0% by weight and 50.0% by weight in 0.1% increments (e.g., about 35.1% by weight), or any value between 31.0% by weight and 50.0% by weight in 0.1% increments (e.g., about 31.3% by weight to about 31.8% by weight) based on the total weight of the coated particle. In some embodiments, the one or more polymers are present in an amount of about 31.0% by weight to about 40.0% by weight (or any value between 31.0% by weight and 40.0% by weight in 0.1% increments (e.g., about 31.0% by weight), or any value between 31.0% by weight and 40.0% by weight in 0.1% increments (e.g., about 31.3% by weight to about 31.8% by weight).

[0047] Preparation method The matting agent of the present invention may be prepared by contacting a porous silica particle with (i) one or more waxes, (ii) one or more polymers, or (iii) any combination of (i) and (ii), to produce a coated porous silica particle having a particle surface, and based on the total weight of the coated particle, the (i) one or more waxes, (ii) one or more polymers or (iii) greater than 30.0 wt. % of any combination of (i) and (ii). Any conventional method may be used to contact the porous silica particles with (i) one or more waxes, (ii) one or more polymers or (iii) any combination of (i) and (ii) to produce the coated porous silica particles.

[0048] In some embodiments, the contacting step may be a wet process. The wet contacting step may include dissolving (i) one or more waxes, (ii) one or more polymers, or (iii) any combination of (i) and (ii) in a solvent to form a solvent mixture, incorporating porous silica particles into the solvent mixture, and removing or evaporating the solvent from the solvent mixture to form coated silica particles.

[0049] The coated silica particles may then be subjected to size reduction. Any known particle size reduction method may be used, including but not limited to a grinding process, such as grinding in a ball mill or a pestle and mortar. In one embodiment, the coated particles are subjected to a size reduction process, in which the average particle size of the coated particles is reduced to a first average particle size of less than about 500 microns (μm).

[0050] Once reduced in size, the coated silica particles are then desirably heat treated at an elevated temperature for a heat treatment time. Typically, the elevated temperature is from about 90° C. to about 140° C. (or any value from 90° C. up to 140° C. in 1.0° C. increments (e.g., about 100° C.), or any value in a range from 90° C. up to 140° C. in 1.0° C. increments (e.g., about 91.0° C. to about 102.0° C.)). Typically, the heat treatment time is in the range of from about 1.0 hour (hr) to about 4.0 hr (or any value from 1.0 hr up to 4.0 hr in 1.0 minute increments (e.g., about 1.0 hr and 9 min), or any value in a range from 1.0 hr up to 4.0 hr in 1.0 minute increments (e.g., between about 1.0 hr and 9 min to about 2.0 hr and 5 min)).

[0051] In one exemplary embodiment where one or more wax coatings are present, the elevated temperature for the heat treatment step ranges from about 100° C. to about 130° C. and the heat treatment time ranges from about 1.0 hr to about 1.5 hr. In another exemplary embodiment where one or more polymers are present, the elevated temperature for the heat treatment step ranges from about 90° C. to about 100° C. and the heat treatment time ranges from about 2.5 hr to about 3.5 hr.

[0052] Following any heat treatment step, the heat treated coated silica particles can be cooled. After cooling, the heat treated particles can then be optionally further reduced in size to produce a final particle size of less than about 100 μm (or any value less than about 100 μm in 1.0 μm increments (e.g., about 45.0 μm), or any range of values ​​in 1.0 μm increments from about 1.0 μm up to 100 μm inclusive (e.g., about 4.0 μm to about 6.7 μm). As above, any well known method of reducing particle size can be used. In one exemplary embodiment, a milling step can be used to produce coated particles having a final particle size of less than about 45.0 μm.

[0053] In another exemplary embodiment, the contacting step may be free of any solvent and therefore may be a dry process. In one embodiment, the dry process may include melting (i) one or more waxes, (ii) one or more polymers, or (iii) any combination of (i) and (ii) to form a liquid coating and incorporating the porous silica particles into the liquid coating. In yet another embodiment, the dry process may include melting (a) (i) one or more waxes, (ii) one or more polymers, or (iii) any combination of (i) and (ii) to form a liquid coating. and (b) porous silica particles at an elevated temperature (i.e., at a temperature where either the wax and / or the polymer melts, as appropriate) in a conventional mixer. Conventional mixers include ribbon blenders, Henschel mixers, fluid energy mills (FEM), or atomizing jet mills. In these embodiments, the heating and particle size reduction steps are combined. Also, additional particle size reduction may or may not be required.

[0054] In some exemplary embodiments, crosslinking of polymer-coated silica particles is desirable for better stability and properties. In another exemplary embodiment, crosslinking comprises a vulcanization step. In the process comprising a vulcanization step, elemental sulfur, vulcanization accelerator, or both, can be added to one or more polymers during the contacting step. Suitable vulcanization accelerators for use in the present invention include, but are not limited to, elemental sulfur and butyl dimate.

[0055] Coating Composition The matting agents of the present invention are useful for preparing coating compositions comprising an aqueous suspension or dispersion of the matting agents described herein. In a preferred embodiment, the coating composition is an aqueous coating composition.

[0056] The coating composition includes the disclosed coated silica product in addition to various other ingredients used in the coating composition. Examples of other ingredients that may be present in the composition include water-based binder resins such as Neocryl® KX12, a self-crosslinking modified acrylic copolymer emulsion or LATEX acrylic binder, and coalescing solvents such as dipropylene glycol n-butyl ether (DOWANOL™ PDnB). The composition may or may not contain color pigments, such as organic pigments. If the composition contains color pigments, dispersants may be included in the formulation. If the composition does not contain color pigments, the composition is called a clear coat. Clear coats are preferred for wood coatings because the natural color and natural grain structure of woods such as teak, cherry, oak, walnut, mahogany, and rosewood are highly valued in applications such as furniture and wood carvings.

[0057] The balance of the composition is typically water. Other diluents, such as aliphatic hydrocarbons, aromatic hydrocarbons, alcohols, ketones, white spirits, petroleum distillates, esters, glycol ethers, low molecular weight synthetic resins, and the like, may be included in addition to water. Environmentally friendly diluents, such as water, are preferred.

[0058] Other additives may be included in the composition including, but not limited to, additives to adjust surface tension, improve flow, improve finish appearance, increase wet edge, improve pigment stability, add anti-freeze properties, control foaming, control skinning, etc. Further additives that may be included in the composition include, but are not limited to, catalysts, thickeners, stabilizers, emulsifiers, texturizing agents, adhesion promoters, UV stabilizers, deglossing agents, biocides to combat bacterial growth, etc. Oils may be included as rheology agents, gloss modifiers and protectants to reduce damage to the coating that may otherwise occur from the formation process and degradation components in the supply environment of the material being coated.

[0059] The coating compositions of the present invention typically contain (I) about 1.0% by weight to about 99.0% by weight of a matting agent (or any value between 1.0% by weight and 99.0% by weight in 0.1% increments (e.g., about 5.1% by weight), or any value between 1.0% by weight and 99.0% by weight in 0.1% increments (e.g., about 1.3% to about 4.8% by weight)) and (II) about 99.0% by weight to about 1.0% by weight (or any value between 99.0% by weight and 1.0% by weight inclusive in 0.1% increments (e.g., about 95.1% by weight), or 99.0% by weight to 1.0% by weight inclusive in 0.1% increments (e.g., about 99.0% by weight to 1.0% by weight inclusive) of one or more additional components. The total weight of the coating composition may range from about 98.3% to about 94.8% by weight, including both components (I) and (II).

[0060] use The present invention further relates to the use of the matting agent in various coating applications / processes.When used as a matting agent in a coating composition, the coated silica particles described herein provide one or more improved properties in the final coating, such as improved chemical resistance, improved thermal stress resistance, improved weatherability, improved coating transparency, or any combination thereof.

[0061] In a preferred embodiment, the matting agent of the present invention is useful in a method for improving the chemical resistance, thermal stress resistance, weather resistance and / or film transparency of a coating composition applied to a substrate. In a particularly preferred embodiment, the substrate is a wood substrate. In a preferred embodiment, the wood substrate is treated with the aqueous coating composition, and the coating composition comprises the matting agent of the present invention on the surface of the wood substrate. Other substrates that can be coated with the coating composition according to the present invention include, but are not limited to, leather, plastic (e.g., vinyl), metal (e.g., coil) or alloy, cement or concrete or other industrial finishes.

[0062] In general, the method of using the matting agent in the coating composition according to the present invention includes incorporating the inventive matting agent into the coating composition, preferably an aqueous coating composition, prior to applying the coating composition to a substrate. A typical incorporation step includes mixing or dispersing the matting agent into the formulation. The method of applying the coating composition to a substrate includes brushing, rolling, spraying, drawdown or other possible methods. As further discussed in the examples below, the incorporation of the matting agent of the present invention into a coating composition (e.g., a wood substrate coating composition) and the subsequent application of the coating composition provide a coated film having improved chemical resistance, improved thermal stress resistance, improved weather resistance and / or improved film transparency compared to known coatings / films that do not contain the matting agent of the present invention. For example, in some embodiments, the coating composition containing the matting agent produces a clearcoat film on a substrate, the film having a film transparency ΔL of less than 7.0 units, as measured using a portable Spectro-Guide 45 / 0 colorimeter and the method described in the examples below. * (or any value less than 7.0 units in increments of 0.1 units (e.g., 2.4 units), or any range of values ​​less than 7.0 units in increments of 0.1 units (e.g., about 1.2 units to about 2.4 units)).

[0063] In some embodiments, a coating composition comprising the matting agent of the present invention produces a coating film coated on a substrate, the coating having a water damage (24 hr) ΔL of less than 5.0 units as measured using a handheld Spectro-Guide 45 / 0 colorimeter and the method described in the Examples below. * (or any value less than 5.0 units in increments of 0.1 units (e.g., 2.4 units), or any range of values ​​less than 5.0 units in increments of 0.1 units (e.g., about 1.2 units to about 2.4 units)).

[0064] In some embodiments, the inventive coating composition including the matting agent produces a coating film coated on a substrate, the coating having a 50 / 50 water / ethanol damage (1 hr) ΔL of less than 8.0 units as measured using a handheld Spectro-Guide 45 / 0 colorimeter and the method described in the Examples below. * (or any value less than 5.0 units in increments of 0.1 units (e.g., 2.4 units), or any range of values ​​less than 5.0 units in increments of 0.1 units (e.g., about 1.2 units to about 2.4 units)).

[0065] In some embodiments, a coating composition comprising the coated particles described herein produces a coating on a substrate, the coating having a 50 / 50 water / ethanol damage (4 hr) ΔL of less than 16.0 units, as measured using a handheld Spectro-Guide 45 / 0 colorimeter and the method described in the Examples below. * (or any value less than 16.0 units in increments of 0.1 units (e.g., 12.4 units), or any range of values ​​less than 16.0 units in increments of 0.1 units (e.g., about 10.2 units to about 12.4 units)).

[0066] In some desirable embodiments, a coating composition comprising the coating particles described herein produces a coating on a substrate, the coating having (i) a coating transparency ΔL of less than 7.0 units, as measured using a handheld Spectro-Guide 45 / 0 colorimeter and the method described in the Examples below. * (or any value less than 7.0 units in increments of 0.1 units (e.g., 2.4 units), or any range of values ​​less than 7.0 units in increments of 0.1 units (e.g., from about 1.2 units to about 2.4 units)); (ii) a water damage (24 hr) ΔL of less than 4.0 units *(or any value less than 4.0 units in 0.1 unit increments (e.g., 2.4 units), or any range of values ​​less than 4.0 units in 0.1 unit increments (e.g., about 1.2 units to about 2.4 units)); (iii) a 50 / 50 water / ethanol injury (1 hr) ΔL of less than 8.0 units * (or any value less than 5.0 units in 0.1 unit increments (e.g., 2.4 units), or any range of values ​​less than 5.0 units in 0.1 unit increments (e.g., about 1.2 units to about 2.4 units)); (iv) a 50 / 50 water / ethanol injury (4 hr) ΔL of less than 10.0 units * (or any value less than 10.0 units in increments of 0.1 units (e.g., 8.4 units), or any range of values ​​less than 10.0 units in increments of 0.1 units (e.g., about 7.2 units to about 7.4 units)).

[0067] Without wishing to be bound by any particular theory, it is hypothesized that the improved matting agent and improved chemical resistance / thermal stress resistance properties exhibited by the development of the coating may be due to one or more of the following factors: 1) reduced particle shrinkage during drying; 2) improved adhesion between the matting particles and the latex; 3) ability for the wax / organic coating to flow better and fill cracks as it forms; 4) reduced stress on the latex particle interface by softening the latex in the area surrounding the particle; and 5) diffusion of the latex into the coating pores, thereby reducing the penetration of water and ethanol into the coating.

[0068] Although the coated particles, methods and uses described above are described as "comprising" one or more components or steps, it is understood that the coated particles, methods and uses described above can "comprise," "consists of," or "consist essentially of" any described components or steps, methods and uses of the coated particles. As a result, it is not intended that the invention, or portions thereof, "comprise" any of the disclosed components or steps. When the invention or portions thereof are described in open-ended terms such as "comprising," "constitutes," or "includes," the description may also (unless otherwise specified) be amended to include the terms "consisting essentially of" or "consisting of," or variations thereof as discussed below. It should be readily understood that the present invention should be construed as describing the present invention or any portion thereof using the above-mentioned terms.

[0069] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," "containing," "featuring," or any other variation thereof, are intended to cover any and all aspects expressly indicated to the contrary. The term "coated product" is intended to include a non-exclusive inclusion of the listed components, subject to limitations. For example, a coated product that "comprises" a series of elements (e.g., components or steps) may be The particles, methods and / or uses described are not necessarily limited to only these elements (or components or steps), but may include other elements (or components or steps) not expressly listed or inherent to the particles, methods and / or uses.

[0070] As used herein, the transitional phrases "consists of" and "consist of "Consisting of" excludes any element, step, or ingredient not specified. For example, "consists of" and "consisting of" used in a claim limit the claim to the components, materials, or steps specifically recited in the claim, excluding impurities ordinarily associated therewith (i.e., impurities within a given component). When the phrase "consists of" or "consisting of" appears within a clause in the body of a claim rather than immediately following the preamble, the phrase "consists of" is used interchangeably with "consisting of" or "consisting of." "Of" or "consisting of" limits only the elements (or components, or steps) listed in that clause and does not exclude other elements (or components) from the claim as a whole.

[0071] As used herein, the transitional phrase "consists essentially of " and "consisting essentially of" are literally disclosed. "Consisting essentially of" is used to define coated particles, methods and / or uses that include materials, steps, features, ingredients, or elements in addition to those described herein, provided that these additional materials, steps, features, ingredients, or elements do not materially affect the basic and novel characteristic(s) of the invention being claimed. The term "consisting essentially of" lies in the middle ground between "comprising" and "consisting of."

[0072] The present invention is further illustrated by the following examples, which are not to be construed as imposing limitations on its scope in any way. On the contrary, it is clearly understood that various other embodiments, modifications, and equivalents thereof can be relied upon, which may suggest themselves to those skilled in the art upon reading the description herein, without departing from the spirit of the invention and / or the scope of the appended "claims". EXAMPLES

[0073] The following examples describe (i) a process according to the present invention for preparing coated particles and (ii) evaluation of the coated particles in a coating composition.

[0074] Example 1 - Formation of wax-coated silica particles (wet method): 2.5-10 grams of wax was dissolved in 60-100 mL of toluene with heating. 10 g of SYLOID® C807 silica particles were mixed with the wax solution. The mixture was left in a crystallizing dish overnight in a well-ventilated fume cupboard to allow all the solvent to evaporate. The "dried" residue was subjected to a mortar and pestle to allow all the particles to pass through a 500 μm screen. The sieved particles were then heated at 130° C. for 1 hour. After drying, the particles were allowed to cool and the particle size was further reduced using an analytical mill to allow the particles to pass through a 45 μm screen. The sieved particles were suitable for use directly as is, e.g. in coating formulations.

[0075] Example 2 - Formation of polyisoprene coated silica particles using a vulcanization process (wet method): 4.3 grams of polyisoprene (KL-10, 10 kDMW, mostly trans-isomer, available from Kuraray) was dissolved in 60 mL of toluene. 0.24 g of elemental sulfur and 0.12 g of butyl dimate (Vanderbilt Chemicals, A 10 g quantity of SYLOID® C807 silica particles was mixed with the solution. The mixture was left in a crystallizing dish overnight in a well-ventilated fume cupboard to allow all the solvent to evaporate. The "dried" residue was then subjected to a mortar and pestle to allow all the particles to pass through a 500 μm screen. The sieved particles were then heated at 95° C. for 3 hours. The particles were then cooled and further reduced in particle size using an analytical mill to allow most of the particles to pass through a 45 μm screen. The sieved particles were suitable for use directly as is, for example in coating formulations.

[0076] Example 3 - Formation of polyisoprene coated silica particles without a vulcanization step (wet process): 7.0 grams of polyisoprene (KL-10, 10 kD MW, mostly trans, available from Kuraray) was dissolved in 60 mL of toluene. 10 g of SYLOID® C807 silica particles were mixed with the solution. The mixture was left in a crystallizing dish overnight in a well-ventilated fume cupboard to allow all solvent to evaporate. The "dried" residue was then subjected to a mortar and pestle to allow all particles to pass through a 500 μm screen. The sieved particles were then heated at 70° C. for 3 hours. The particles were then cooled and further reduced in particle size using an analytical mill to allow most particles to pass through a 45 μm screen. The sieved particles were suitable for use directly as is, for example in coating formulations.

[0077] Example 4 - Formation of Melted and Mixed Wax Coated Silica Particles (Dry Method): 4 kg of SYLOID® C807 silica particles and 4 kg of POLARWACHS® N481 polyethylene wax were mixed in a 10 L Henschel mixer under nitrogen. The mixer was heated to 120° C. for 2 hours. The mixer was mixed at 3000 rpm for 2 hours. The sample was then cooled to room temperature.

[0078] Example 5 - Formation of molten and ground wax coated silica particles (dry method): 4 kg of silica gel (~30 μm particle size, pore volume 2 cc / g) was mixed with 4 kg of POLAR WACHS® N481 polyethylene wax in a 10 L Henschel mixer under nitrogen. The mixer was heated to 120°C for 2 hours. The mixer was mixed at 3000 rpm for 2 hours. The sample was cooled to room temperature and the compound was subjected to a fluid energy mill under nitrogen resulting in a particle size of 9 μm (median particle size).

[0079] Example 6 - Formation of test stock solutions of coating compositions The ingredients listed in Table 1 below were combined as described below to form test stock solutions of the coating compositions discussed below.

[0080] [Table 1]

[0081] 77.43 grams (g) of NEOCRYL® KX12 and 5.53 g of deionized water were mixed in a first container. 8.85 g of DOWANOL™ PDnB and 5.54 g of deionized water were mixed in a second container. The contents of the second container were then slowly poured into the first container. The mixture was dispersed at 1500 rpm for 15 minutes using a DISPERMAT® disperser manufactured by Gardner Company (Pompano Beach, FL) equipped with a 30 mm wide blade.

[0082] 0.55 g of BYK® 024, 1.11 g of SURFYNOL® 104E, and 0.22 g of RHEOLATE® 299 were added to the mixture in the first container. The mixture was then dispersed using a DISPERMAT® disperser at 2500 rpm for 10 minutes.

[0083] 0.77 g of BYK® 346 was added to the mixture in the first container. The mixture was then dispersed using a DISPERMAT® disperser at 1000 rpm for 5 minutes. The resulting mixture was then used as a stock solution that can be stored for up to one month.

[0084] Example 7 - Formation of a coating composition containing a matting agent and a concentrate A coating composition containing a matting agent and the stock solution of Example 6 was prepared as follows: A given amount of the matting agent was added to a given amount of the stock solution formed in Example 3 above, and the resulting mixture was dispersed using a DISPERMAT® disperser at 2500 rpm for 30 minutes. Then, it was left at room temperature overnight.

[0085] For each coating composition tested, a drawdown was performed on the second day (ie, the day after a given coating composition was made) using the drawdown procedure described below.

[0086] Drawdown Procedure and Drawdown Card The drawdown was performed using a wound lab rod manufactured by Gardner Company with a wire size of 40. With this size, the wet film thickness was approximately 100 μm. The drawdown plate used was a 219×286 mm 300 mm 320 mm 360 mm 38 ... 2 The procedure for each drawdown was as follows: 1. In a dust-free clean room, a blank drawdown plate was placed in a vacuum holder. 2. Using a pipette, approximately 2-5 mL of the well-mixed coating composition sample was placed on and adjacent to the sample sheet. 3. The end of the drawdown rod was quickly grasped, using the thumbs of both hands to prevent the rod from breaking or bending away from the sample, and the drawdown rod was pulled down through the pool of liquid, spreading and metering the fluid across the sample sheet. After a given drawdown was achieved, the drawdown rod was immersed in a post-use wash tray. 4. After drawdown, the drawdown samples were left at room temperature for at least 4 days to allow the coating layer to dry completely. 5. After the coated drawdown plates were dried, they were tested for chemical resistance, coating transparency, matte effect and low temperature verification using the following procedures.

[0087] Gloss (matt effect), transparency and chemical resistance of coatings measurement and test methods: A handheld Micro-TRI-Gloss meter (BYK-Gardner, Columbia, MD, USA) was used to measure the coating gloss. 60° gloss values ​​were measured and reported.

[0088] A handheld Spectro-Guide 45 / 0 colorimeter (BYK-Gardner) was used to check the transparency and chemical damage of the coatings. * The values ​​were obtained by measuring with a colorimeter. For the card with a black background, about 7.9 L of the unmattified stock solution (according to Example 6) was removed. * The addition of a matting agent (e.g., silica) to the stock solution resulted in a whiter coating (i.e., a higher L * The transparency of the matte coating is obtained by the new L * Value and L derived from a coating formed from a stock solution that does not contain a matting agent * was defined as the difference between the

[0089] The chemical resistance test method used was similar to the European standard EN 12720 / DIN 68861-1. Resistance to deionized water and 50 / 50 ethanol in water was tested. The test was carried out as follows: 1. A circle (1 inch diameter) was cut from Fisherbrand filter paper. 2. The circles were immersed in either water or 50 / 50 ethanol / water for 30 seconds. 3. Each dipped circle was placed on a dry drawdown card and then covered with a weighing dish to prevent evaporation. 4. After a period of time (ie, 24 hours for the water tests, and 1 hour and 4 hours for the 50 / 50 ethanol in water tests), the weighing dish and paper were removed. 5. A white mark is made in the contact area, and after overnight, the L is measured using a Spectro-Guide 45 / 0 colorimeter. * The values ​​were measured. 6. Chemical damage (inversely proportional to chemical resistance) is indicated by the white mark L * The change was defined as the difference between the value (i.e., the largest measurement of at least three measurements) and the coating base. The rate was also calculated.

[0090] Low temperature confirmation test This test was designed to simulate weathering and relative humidity changes that affect the water resistance and water penetration of a given coating. The test was carried out by subjecting the dried drawdown cards to the following environment for 5 cycles (5 cycles: 1st stage at -20°C for 1 hour, 2nd stage at 50°C for 1 hour at 95% relative humidity). This was then repeated for a total of 5 cycles. After these cycles, the L * values ​​were measured and compared to these pre-cycle values.

[0091] Example 8 - Formation of coated particles of the present invention Sample coated particles were prepared using the materials shown below in Table 2. The first nine samples were prepared using the procedure outlined above in Example 1. Sample 10 was prepared using the procedure outlined in Example 4, and Sample 11 was prepared using the procedure outlined in Example 5.

[0092] [Table 2]

[0093] Example 9 - Comparative particles The comparative particles shown in Table 3 below were used as received without further modification.

[0094] [Table 3]

[0095] In Table 3, in Comparative Example 4, the organic used is CERAFLOUR® 920, which is a urea-formaldehyde based organic matting agent, and in Comparative Example 5, the wax used is CERAFLOUR® 929, which is a micronized polyethylene wax based organic matting agent. Both are commercially available from BYK-Chemie GmbH (Wesen, Germany). In both Comparative Examples 4 and 5, a mixture of pure silica and an organic matting agent (a physical blend of the two matting agents) is used in the coating formulation.

[0096] Example 10 - Formation of specific coating compositions Matting agent-containing coating compositions were prepared using the coated particles of Example 8 of the present invention and the comparative sample particles of Example 9. Each matting agent-containing coating composition was prepared using the procedure described in Example 7 above. After formation, each matting agent-containing coating composition was drawn down using the drawdown procedure described herein. After drying, each of the resulting coatings was evaluated for gloss, coating clarity, and chemical resistance according to the methods described above. The results are summarized in Table 4 below.

[0097] [Table 4]

[0098] As shown in Table 4 above, all of the wax-coated matting agents of the present invention exhibited improved chemical resistance when compared to that obtained from the comparative samples. In Samples 1-4 and Comparative Sample 1, as the amount of wax increased, a lower ΔL * The chemical resistance was increased as expressed by the value.

[0099] Also, when compared to Sample 9 and Comparative Samples 4 and 5, the wax coating provided chemical resistance that was much better than a simple physical blend of silica and an organic matting agent.

[0100] Table 5 below shows the improved low temperature validation of coatings formed with coated particles of the present invention using the low temperature validation test method described herein.

[0101] [Table 5]

[0102] As shown, a significant reduction in "white color" was obtained for the wax coating (0% change vs. 41% change).

[0103] Example 11 - Formulation of additional specific coating compositions Two additional matting agent-containing coating compositions were prepared using (i) polyisoprene-coated silica (4.3 g polyisoprene and 10 g vulcanized SYLOID® C807 silica gel particles) formed using the procedure described in Example 2 above, (ii) polyisoprene-coated silica (7.0 g polyisoprene and 10 g unvulcanized SYLOID® C807 silica gel particles) formed using the procedure described in Example 3 above, and (iii) the comparative particles designated in Comparative Example 1 above. Each matting agent-containing coating composition was prepared using the procedure described in Example 7 above. After formation, each matting agent-containing coating composition was drawn down using the drawdown procedure described herein. After drying, each of the resulting coatings was evaluated for gloss, coating clarity, and chemical resistance according to the methods described above. The results are summarized in Table 6 below.

[0104] [Table 6]

[0105] As shown above in Table 6, polyisoprene coated silica particles (with or without vulcanization) provided significant improvement in chemical resistance compared to unmodified silica particles.

[0106] Although the present invention has been described with a limited number of embodiments, these specific embodiments are not intended to limit the scope of the invention as described and claimed elsewhere herein. Further modifications, equivalents, and variations are possible and may become apparent to one of ordinary skill in the art upon reviewing the exemplary embodiments herein. All parts and percentages in the examples and the remainder of the specification are by weight unless otherwise specified. Furthermore, any range of numbers recited in the specification or claims, such as expressing a particular set of properties, units of measure, conditions, physical states, or percentages, is intended to be literally and explicitly included, by reference or otherwise indicating, all numbers contained within such ranges, as well as all subsets of numbers within all ranges so recited. For example, a lower limit R L and upper limit R U Whenever a numerical range with Specifically disclosed are any numbers R within the range: R = R L +k(R U -R L ) (where k is a variable ranging from 1% to 100% in 1% increments, e.g., k is 1%, 2%, 3%, 4%, 5%....50%, 51%, 52%....95%, 96%, 97%, 98%, 99%, or 100%). Furthermore, any numerical range represented by any two values ​​of R as calculated above is specifically disclosed. Any modifications of the present invention, in addition to those shown and described herein, will become apparent to those skilled in the art from the foregoing description and accompanying drawings. Such modifications are intended to fall within the scope of the appended "claims". All publications cited herein are incorporated by reference in their entirety.

Claims

1. 1. A matting agent for an aqueous composition to be applied to a wood substrate, comprising: Silica particles having a particle surface, wherein the silica particles comprise silica gel or precipitated silica; one or more waxes coated on the particle surface; Including, the one or more waxes comprising 40.0 to 50 weight percent (wt %) based on the total weight of the silica particles and the one or more waxes; the one or more waxes comprising polyethylene wax, polypropylene wax, carnauba wax, or any combination thereof; The above-mentioned matting agent.

2. The matting agent of claim 1 , wherein the silica particles comprise silica gel.

3. 10. The matting agent of claim 1, wherein the silica particles have a total pore volume, as measured by the Barrett-Joyner-Halenda (BJH) method, of from 0.30 cc / gm to 2.20 cc / gm.

4. 4. The matting agent of claim 3, wherein the silica particles have a total pore volume, as measured by the BJH method, of from 0.40 cc / gm to 2.20 cc / gm.

5. 4. The matting agent of claim 3, wherein the silica particles have a total pore volume, as measured by the BJH method, of 1.8 cc / gm to 2.0 cc / gm.

6. The silica particles are 100 m ２ / g~1500m ２ 10. The matting agent of claim 1 having a BET particle surface area of ​​1000 nm / g.

7. The silica particles are 200 m ２ / g~900m ２ 7. The matting agent of claim 6, having a BET particle surface area of ​​1 / g.

8. 2. The matting agent of claim 1, wherein the silica particles have an average particle size of 1.0 microns (μm) to 50 μm.

9. 10. The matting agent of claim 1, wherein the one or more waxes comprise POLARWACHS® N481 polyethylene wax.

10. 3. A coating composition comprising the matting agent of claim 1 or 2, wherein the coating composition comprises an aqueous composition.

11. A substrate, including a wood substrate, coated with the coating composition of claim 10.

12. 10. A method for preparing the matting agent of claim 1, said method comprising: contacting said silica particles with said one or more waxes to form coated silica particles.

13. 13. The method of claim 12, The contacting step comprises: dissolving the one or more waxes in a solvent to form a suspension or dispersion; incorporating said silica particles into said suspension or dispersion; removing the solvent from the suspension or dispersion to form coated silica particles; The contacting step comprises: melting the one or more waxes to form a liquid coating; incorporating the silica particles into the liquid coating to form coated silica particles; or The contacting step comprises: (a) the one or more waxes and (b) the silica particles are simultaneously mixed or milled while being heated to form coated silica particles. method.

14. 14. The method of claim 13, wherein the contacting step further comprises melting one or more polymers, and the method further comprises adding elemental sulfur, a vulcanization accelerator, or both to the one or more polymers.

15. The method of claim 14, wherein the vulcanization accelerator comprises butyl dimate.

16. 15. The method of claim 13 or 14, further comprising reducing the particle size of the coated silica particles to obtain particles having a final particle size of less than 100 microns (μm).

17. forming coated silica particles having a first particle size of less than 500 microns (μm); heat treating the coated particles at an elevated temperature for a heat treatment time; allowing the heat-treated coated particles to cool; and grinding the heat-treated coated particles to produce a final particle size of less than 100 μm; wherein the coated particles are heat-treated at a high temperature ranging from 90°C to 140°C, and the heat-treatment time is ranging from 1.0 hour (hr) to 4.0 hours; 17. The method of claim 16.

18. 18. The method of claim 17, wherein one or more waxes are present, the elevated temperature is in the range of 100°C to 130°C, and the heat treatment time is in the range of 1.0 hr to 1.5 hr.

19. A coating composition comprising 5.00 to 6.00% by weight of the matting agent according to claim 1.

20. 20. A substrate coated with the coating composition of claim 19.

21. 1. A method for improving chemical resistance, thermal stress resistance, weather resistance, coating transparency, or any combination thereof, of an aqueous composition applied to a wood substrate, said method comprising: applying the coating composition of claim 19 to at least one surface of a wood substrate to form a coating; allowing the coating to dry to form a film on at least one surface of the wood substrate; A method comprising: