Glitter pigment and method for producing glitter pigment

Abstract

Provided is a glitter pigment in which the pigment is effectively inhibited from shedding off. The glitter pigment comprises: a glitter base; a first film which covers at least a portion of the surface of the glitter base and which includes a silane coupling agent; and a pigment complex which is adhered to the surface of the first film and comprises an organic pigment and a resin covering at least a portion of the surface of the organic pigment. This method for producing the glitter pigment comprises: treating the surface of a glitter base with a first surface-treating agent including a silane coupling agent to form a first film including the silane coupling agent on at least a portion of the surface; preparing an aqueous dispersion which includes both the glitter base having the first film formed thereon and a pigment complex comprising an organic pigment and a resin covering at least a portion of the surface of the organic pigment; and adhering the pigment complex to the surface of the first film.

Description

Bright pigment and method for producing bright pigment

[0001] The present invention relates to a bright pigment and a method for producing the bright pigment.

[0002] Known luster pigments include thin flaky particles such as glass flakes and mica flakes coated with metal, and metal powders such as aluminum. Known luster pigments with pearlescent luster include thin flaky particles such as mica flakes, synthetic mica flakes, flaky silica, flaky alumina, glass flakes, and graphite flakes coated with a coating layer containing titanium dioxide or iron oxide, and iron oxide particles containing α-iron oxide crystals as the main component. These luster pigments are used alone in, for example, cosmetics, inks, and coating compositions, or as fillers that impart a luster to resin compositions.

[0003] Patent Document 1 discloses a colored luster pigment characterized in that the surface of a glass flake is coated with a silica-based film containing an organic pigment. In Patent Document 1, by coating the surface of the glass flake with a silica-based film containing an organic pigment, it is possible to prevent the organic pigment from falling off, and to improve the transparency, luster, and saturation of the luster pigment.

[0004] Japanese Patent Application Laid-Open No. 2006-176742

[0005] The bright pigment of Patent Document 1 can provide excellent transparency, brightness, and clear colors. However, according to the inventors' investigations, there is room for improvement in suppressing pigment shedding. For example, if the bright pigment of Patent Document 1 is stirred with a paint for a long period of time, the organic pigment may be shedding from the surface of the glass flakes, and the desired effects of brightness, saturation, etc. may not be achieved.

[0006] An object of the present invention is to provide a bright pigment having an improved effect of suppressing pigment shedding. Another object of the present invention is to provide a method for producing a bright pigment having an improved effect of suppressing pigment shedding.

[0007] In one aspect, the present invention provides a glittering pigment comprising: a glittering substrate; a first film covering at least a portion of the surface of the glittering substrate and containing a silane coupling agent; and a pigment complex attached to the surface of the first film, the pigment complex including an organic pigment and a resin covering at least a portion of the surface of the organic pigment.

[0008] In another aspect, the present invention provides a method for producing a glittering pigment, the method comprising: treating the surface of a glittering substrate with a first surface treatment agent containing a silane coupling agent to form a first film containing the silane coupling agent on the surface; and preparing an aqueous dispersion containing: a pigment complex containing an organic pigment and a resin that covers at least a portion of the surface of the organic pigment; and the glittering substrate on which the first film has been formed; and adhering the pigment complex to the surface of the first film.

[0009] According to the present invention, a bright pigment is provided that has an improved effect of suppressing pigment shedding.

[0010] 1A is a cross-sectional view schematically showing an example of a bright pigment according to the present embodiment; FIG. 1B is a partial enlarged view of FIG. 1A; FIG. 1C is a schematic diagram illustrating an example of a manufacturing apparatus for glass flakes; and FIG. 1D is a schematic diagram illustrating another example of a manufacturing apparatus for glass flakes.

[0011] A bright pigment according to a first aspect of the present invention comprises: a bright base material; a first film covering at least a portion of the surface of the bright base material and containing a silane coupling agent; and a pigment complex attached to the surface of the first film, the pigment complex including an organic pigment and a resin covering at least a portion of the surface of the organic pigment.

[0012] In a second aspect of the present invention, for example, the bright pigment according to the first aspect further comprises a second film containing silica as a main component, and the second film covers at least a portion of the surface of the pigment complex.

[0013] In a third aspect of the present invention, for example, in the bright pigment according to the second aspect, the second film covers at least a part of the surface of the first film.

[0014] In a fourth aspect of the present invention, for example, in the shiny pigment according to any one of the first to third aspects, the shiny substrate comprises a flaky substrate and an optical functional film formed on at least a portion of the surface of the flaky substrate, and the optical functional film has at least one function selected from the group consisting of light reflection and coloring.

[0015] In a fifth aspect of the present invention, for example, in the bright pigment according to the fourth aspect, the optical functional film contains titanium oxide.

[0016] A method for producing a glittering pigment according to a sixth aspect of the present invention includes: treating the surface of a glittering base material with a first surface treatment agent containing a silane coupling agent to form a first film containing the silane coupling agent on at least a portion of the surface; and preparing an aqueous dispersion containing: a pigment complex containing an organic pigment and a resin covering at least a portion of the surface of the organic pigment; and the glittering base material on which the first film has been formed; and adhering the pigment complex to the surface of the first film.

[0017] In a seventh aspect of the present invention, for example, in the method for producing a bright pigment according to the sixth aspect, the aqueous dispersion further contains a second surface treatment agent containing a hydrolyzable compound containing a silicon atom or a hydrolysate of the compound, and the method comprises adhering the pigment complex to the surface of the first film and forming a second film containing silica as a main component on at least a portion of the surface of the pigment complex, or on at least a portion of the surface of the pigment complex and at least a portion of the surface of the first film.

[0018] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the following description is for illustrative purposes only and is not intended to limit the scope of the present invention.

[0019] [Matte pigment] Fig. 1A is a cross-sectional view schematically showing an example of a matte pigment 100 according to the present embodiment. Fig. 1B is a partially enlarged view of part B in Fig. 1A.

[0020] As shown in Fig. 1A, the bright pigment 100 includes a bright substrate 10, a first film 21 covering at least a portion of the surface of the bright substrate 10, and a pigment complex 30 attached to the surface of the first film 21. The first film 21 is a film containing a silane coupling agent. As shown in Fig. 1B, the pigment complex 30 includes an organic pigment 31 and a resin 32 covering at least a portion of the surface of the organic pigment 31. The pigment complex 30 is a complex in which at least a portion of the surface of the organic pigment 31 is coated with the resin 32.

[0021] In the bright pigment 100 of this embodiment, the surface of the bright substrate 10 is covered with a first film 21 containing a silane coupling agent, and the surface of the organic pigment 31 is covered with a resin 32. Because the surface of the organic pigment 31 is covered with the resin 32, the pigment complex 30 is less likely to form clumps, and the pigment complex 30 is more likely to be uniformly present near the surface of the first film 21. Furthermore, the interaction between the resin 32 and the first film 21 makes it easier for the pigment complex 30 to adhere to the bright substrate 10. As a result, the organic pigment 31 is less likely to fall off from the bright substrate 10, and this falling off of the organic pigment 31 is suppressed. Therefore, the bright pigment 100 of this embodiment stably provides colors with excellent transparency, brightness, and high saturation.

[0022] 1A and 1B , the bright pigment 100 may further include a second film 22 containing silica as a main component. The second film 22 covers at least a portion of the surface of the pigment complex 30. In this specification, the term "main component" refers to the component that is contained in the second film 22 in the largest amount by mass. The same applies to other materials.

[0023] In the glittering pigment 100 of this embodiment, the surface of the organic pigment 31 is covered with the resin 32, which makes it easier for the second film 22 containing silica as a main component to be formed on the surface of the pigment complex 30. The second film 22 contributes to improving the adhesion between the glittering substrate 10 and the pigment complex 30. As a result, the organic pigment 31 is less likely to fall off from the glittering substrate 10, and falling off of the organic pigment 31 is further suppressed.

[0024] 1A and 1B, the second film 22 may cover at least a portion of the surface of the first film 21. The second film 22 may include a pigment complex 30.

[0025] In the shiny pigment 100 of this embodiment, the pigment complex 30 tends to be uniformly present near the surface of the first film 21, and the interaction between the resin 32 and the first film 21 makes it easy for the pigment complex 30 to adhere to the shiny substrate 10. This reduces the proportion of the organic pigment 31 protruding from the second film 22. As a result, the organic pigment 31 is even less likely to fall off from the shiny substrate 10, and falling off of the organic pigment 31 is further suppressed.

[0026] The glittering substrate 10 may include a flaky substrate 11 and an optical functional film 12 formed on at least a part of the surface of the flaky substrate 11. The optical functional film 12 has at least one function selected from the group consisting of light reflection and coloring.

[0027] The glittering substrate 10 has a flaky substrate 11 and an optical functional film 12 formed on at least a portion of the surface of the flaky substrate 11, thereby imparting at least one function selected from the group consisting of light reflection and coloring to the glittering pigment 100. The light reflection function is, for example, an increase in visible light reflectance due to the addition of the optical functional film 12. The coloring function is, for example, the appearance of an interference color due to the optical interference effect involving the optical functional film 12.

[0028] (Flake-shaped substrate) Examples of the flake-shaped substrate 11 include flake glass, mica flakes, synthetic mica flakes, flaked silica, flaked alumina, flaked graphite, etc. The flaked substrate 11 may be flaked glass.

[0029] When the flake-shaped substrate 11 is a flake-shaped glass, a commonly known glass composition can be used as the composition of the flake-shaped glass. However, when an optical functional film 12 is formed on at least a part of the surface of the flake-shaped glass, the composition of the flake-shaped glass is preferably one with excellent acid resistance, and for example, C-glass can be suitably used. A typical composition of C-glass is shown below. The units of the following compositions are in mass %.

[0030] 65≦SiO2≦72 1≦Al2O3≦7 4≦CaO≦11 0≦MgO≦5 9≦(Na2O+K2O)≦17 0≦B2O3≦8 0≦ZnO≦6

[0031] When combined with a resin that is sensitive to alkali components, a glass composition with excellent acid resistance and a low alkali content is preferred. In this case, a glass composition containing the following components, expressed in mass %, and substantially free of BO, F, ZnO, BaO, SrO, and ZrO can be used.

[0032] 59≦SiO2≦65 8≦Al2O3≦15 47≦(SiO2−Al2O3)≦57 1≦MgO≦5 20≦CaO≦30 0<(Li2O+Na2O+K2O)<2 0≦TiO2≦5

[0033] This glass composition was disclosed by one of the applicants in International Publication No. 2006 / 068255. Hereinafter, a glass having this glass composition will be referred to as "TA glass." Note that "substantially free" means that these elements are not intentionally included, except in cases where they are inevitably mixed in with industrial raw materials. Specifically, this means that the content of each of B2O3, F, ZnO, BaO, SrO, and ZrO2 is less than 0.1% by mass, preferably less than 0.05% by mass, and more preferably less than 0.03% by mass.

[0034] The composition of the glass flakes is not limited to the above-mentioned glass compositions of C glass and TA glass, but may also be A glass, E glass, ECR glass, or S glass.

[0035] Glass flakes can be produced by, for example, the so-called blowing method disclosed in Japanese Patent Publication Nos. 41-17148 and 45-3541, or the so-called rotary method disclosed in Japanese Patent Laid-Open Nos. 59-21533 and 2-503669.

[0036] In the blowing method, a glass manufacturing apparatus shown in Fig. 2 can be used. The glass manufacturing apparatus shown in Fig. 2 includes a refractory kiln tank 102, a blow nozzle 105, and a pressure roll 107. A glass melt 101 melted in the refractory kiln tank 102 (melting tank) is inflated into a balloon shape by gas fed into the blow nozzle 105, forming a hollow glass film 106. The hollow glass film 106 is crushed by the pressure roll 107 to obtain glass flakes 11g. The thickness of the glass flakes 11g can be controlled by adjusting the pulling speed of the hollow glass film 106, the flow rate of the gas fed from the blow nozzle 105, and the like.

[0037] In the rotary process, a glass manufacturing apparatus shown in Fig. 3 can be used. The glass manufacturing apparatus shown in Fig. 3 includes a pipe 201, a rotating cup 202, a set of annular plates 203, and an annular cyclone collector 204. The molten glass base 101 is poured from the pipe 201 into the rotating cup 202, flows out radially from the upper edge of the rotating cup 202 due to centrifugal force, passes between the annular plates 203, is sucked by the airflow, and is introduced into the annular cyclone collector 204. While passing through the annular plates 203, the glass cools and solidifies in the form of a thin film and is further crushed into minute pieces, thereby obtaining glass flakes 11g. The thickness of the glass flakes 11g can be controlled by adjusting the spacing between the annular plates 203, the speed of the airflow, etc.

[0038] The average thickness of the flaky substrates 11 may be within a range of 0.1 to 10 μm. The average thickness may be within a range of 0.5 to 1.5 μm. In this specification, the average thickness of the flaky substrates 11 can be determined, for example, by measuring the thickness of the flaky substrates 11 contained in 100 sheets of the bright pigment 100 using a scanning electron microscope (SEM) and averaging the measured values.

[0039] The average particle size of the flaky substrate 11 may be in the range of 0.1 to 2000 μm. The average particle size may be 1.0 μm or more, 10 μm or more, or even 100 μm or more, for example, in the range of 100 to 300 μm. The average particle size may be 200 μm or less. In this specification, the average particle size of the flaky substrate 11 refers to the particle size (D50) at which the cumulative volume from the smaller particle size side in the particle size distribution of the flaky substrate 11 measured based on a laser diffraction / scattering method is 50%.

[0040] (Optical Functional Film) In the glittering substrate 10, the optical functional film 12 covers at least a part of the surface of the flaky substrate 11. The optical functional film 12 may cover the entire surface of the flaky substrate 11.

[0041] The optical function film 12 may be a single-layer film or a multi-layer film.

[0042] Examples of the optical functional film 12 include a metal oxide layer containing titanium oxide, iron oxide, or the like, or a metal layer of silver, copper, aluminum, or the like. By coating the flake-shaped substrate 11 with a metal oxide layer, a bright pigment 100 having a pearlescent luster can be obtained. By coating the flake-shaped substrate 11 with a metal layer, a bright pigment 100 having a metallic luster can be obtained.

[0043] The optical functional film 12 may contain titanium oxide. When the optical functional film 12 contains titanium oxide, it is possible to impart a pearlescent luster to the bright pigment 100.

[0044] In the bright pigment 100, the optical functional film 12 covers at least a portion of the surface of the flake-shaped substrate 11. This allows the bright pigment 100 to have a pearlescent or metallic luster. The optical functional film 12 may also cover the entire surface of the flake-shaped substrate 11.

[0045] The average thickness of the optical functional film 12 is not particularly limited. Considering the improvement of pearlescent or metallic luster, manufacturing costs, etc., the average thickness of the optical functional film 12 is preferably in the range of 0.01 to 0.3 μm, and more preferably in the range of 0.01 to 0.2 μm. The average thickness of the optical functional film 12 can be determined by the same method as that for determining the average thickness of the flake-shaped substrate 11 described above.

[0046] When the optical functional film 12 contains titanium oxide, the optical interference of the optical functional film 12 causes the glittering substrate 10 to develop a color tone corresponding to the thickness of the optical functional film 12. The titanium oxide-containing optical functional film 12 formed on the surface of the flake-shaped substrate 11 exhibits, for example, yellow at an average thickness of approximately 100 nm, red at an average thickness of approximately 130 nm, blue at an average thickness of approximately 160 nm, and green at an average thickness of approximately 175 nm. However, depending on the film formation conditions and other factors, the color tone may vary slightly even if the thickness of the titanium oxide-containing optical functional film 12 is approximately the same. To develop a yellowish color, it is preferable to control the average thickness of the titanium oxide-containing optical functional film 12 to be within a range of 80 nm or more and less than 115 nm. To develop a reddish color, it is preferable to control the average thickness of the titanium oxide-containing optical functional film 12 to be within a range of 115 nm or more and less than 150 nm. To produce a blue color, it is preferable to control the average thickness of the titanium oxide-containing optical functional film 12 to fall within the range of 150 to 165 nm. To produce a green color, it is preferable to control the average thickness of the titanium oxide-containing optical functional film 12 to fall within the range of more than 165 nm and not more than 185 nm. To obtain a blue or green glittering substrate 10, it is preferable to control the average thickness of the titanium oxide-containing optical functional film 12 to fall within the range of 150 to 185 nm, particularly within the range of 155 to 180 nm.

[0047] The optical functional film 12 can be formed on at least a portion of the surface of the flaky substrate 11 using known methods. For example, the method of forming the optical functional film 12 containing titanium oxide on at least a portion of the surface of the flaky substrate 11 can be carried out with reference to the methods disclosed in Japanese Patent Application Laid-Open Nos. 2001-31421 and 2003-12962. According to the methods disclosed in these publications, rutile-type titanium oxide is precipitated on the surface of the flaky substrate 11 in a solution containing a titanium compound such as titanium tetrachloride, thereby forming the optical functional film 12 containing titanium oxide. Rutile-type titanium oxide can be precipitated on the surface of the flaky substrate 11 by adding an alkaline compound or alkaline solution to a solution containing a titanium compound at a temperature of 55 to 85°C and a pH of 1.3 or less. Precipitation of rutile-type titanium oxide is promoted by attaching tin or a tin compound to the flaky substrate 11 in advance. By using this method, the optical functional film 12 containing rutile-type titanium oxide can be formed on the surface of the flaky substrate 11 without the need for heating for crystal transformation.

[0048] Glass flakes having an optical function film 12 containing rutile titanium oxide formed on the surface thereof are sold as Metashine (registered trademark) Titania Coat series by Nippon Sheet Glass Co., Ltd. Such commercially available products may be used as the glittering substrate 10.

[0049] (First Film) In the glitter pigment 100, the first film 21 covers at least a portion of the surface of the glittering substrate 10. The first film 21 may cover the entire surface of the glittering substrate 10.

[0050] The content ratio of the first film 21 relative to the mass of the glittering substrate 10 is preferably within the range of 0.1 to 1 mass %. By keeping the content ratio of the first film 21 within this range, a decrease in glittering sensation due to aggregation of the glittering substrates 10 is suppressed. In this specification, the content ratio of the first film 21 relative to the mass of the glittering substrate 10 can be determined, for example, from the charge amount. The content ratio of the first film 21 relative to the mass of the glittering substrate 10 can also be determined, for example, from the rate of weight loss when the glittering pigment 100 is dried at 110°C for 2 hours and then heated at 500°C for 1 hour.

[0051] The first film 21 contains a silane coupling agent. The first film 21 is a film formed from a first surface treatment agent containing a silane coupling agent as an essential component. Examples of the silane coupling agent include those containing at least one functional group selected from the group consisting of vinyl groups, epoxy groups, styryl groups, methacrylic groups, acrylic groups, amino groups, isocyanate groups, isocyanurate groups, ureido groups, mercapto groups, and acid anhydride groups. The silane coupling agent may be an alkyl-based silane coupling agent containing an alkyl group. Examples of alkyl-based silane coupling agents containing an alkyl group include diethoxydimethylsilane and methyltrimethoxysilane.

[0052] The first surface treatment agent may further contain a tetraalkoxysilane in addition to the silane coupling agent.

[0053] (Second Film) The bright pigment 100 may further include a second film 22 containing silica as a main component. In this case, the second film 22 covers at least a portion of the surface of the pigment complex 30. The second film 22 may also cover the entire surface of the pigment complex 30.

[0054] The second film 22 may further cover at least a part of the surface of the first film 21. The second film 22 may further cover the entire surface of the first film 21.

[0055] As shown in FIG. 1B , the second film 22 covers the entire surface of the glittering substrate 10 on which the first film 21 is formed, and the pigment complex 30 may be included in the second film 22.

[0056] The content ratio of the second film 22 relative to the mass of the glittering substrate 10 is preferably within the range of 5 to 10 mass %. By keeping the content ratio of the second film 22 within the above range, a decrease in glitter caused by aggregation of the glittering substrates 10 is suppressed. In this specification, the content ratio of the second film 22 relative to the mass of the glittering substrate 10 can be determined, for example, from the charge amount.

[0057] The second film 22 contains silica as a main component. The second film 22 may consist solely of silica. In order to adjust the refractive index of the second film 22 and / or impart alkali resistance to the second film 22, the second film 22 may further contain a metal oxide selected from the group consisting of titanium oxide (titania), zirconium oxide (zirconia), and aluminum oxide (alumina), either alone or in combination.

[0058] The second film 22 is a film formed from a second surface treatment agent. The second surface treatment agent contains a hydrolyzable compound containing a silicon atom or a hydrolyzate of the above compound. Examples of hydrolyzable compounds containing a silicon atom include tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane; and methyltrialkoxysilanes such as methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, and methyltributoxysilane. Tetraalkoxysilanes in which the alkoxy group has three or fewer carbon atoms are preferably used because they are likely to form a dense second film 22.

[0059] The second surface treatment agent may contain a hydrolyzable compound containing at least one metal atom selected from the group consisting of titanium, zirconium, and aluminum, in addition to a hydrolyzable compound containing a silicon atom.

[0060] The second surface treatment agent may contain only silicon atoms as metal atoms, and in this specification, silicon atoms are considered to be a type of metal atom.

[0061] (Organic Pigment) The organic pigment 31 may have an average particle size of 10 nm to 1 μm. When the average particle size of the organic pigment 31 is 10 nm or more, the durability of the organic pigment 31 is improved. When the average particle size of the organic pigment 31 is 1 μm or less, the concealment of the glittering substrate 10 by the organic pigment 31 is suppressed, thereby maintaining the glittering appearance of the glittering substrate 10. As a result, deterioration in the color tone of the glittering pigment 100 is suppressed.

[0062] Examples of the organic pigment 31 include phthalocyanine pigments, insoluble azo pigments, azo lake pigments, isoindolinone pigments, quinophthalone pigments, lactone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, diketopyrrolopyrrole pigments, anthrapyridine pigments, anzanthrone pigments, indanthrone pigments, flavanthrone pigments, perinone pigments, perylene pigments, indigo pigments, and thioindigo pigments.

[0063] When the bright pigment 100 is used in an automotive paint or the like, and weather resistance is required for the bright pigment 100, it is preferable to use, as the organic pigment 31, a pigment such as a copper phthalocyanine pigment, a halogenated copper phthalocyanine pigment, an insoluble azo pigment, an isoindolinone pigment, a quinacridone pigment, a diketopyrrolopyrrole pigment, an indanthrone pigment, or a perylene pigment.

[0064] When the bright pigment 100 is used in cosmetics, examples of the organic pigment 31 include red pigments such as Red 2, 3, 102, 104, 105, 106, 201, 202, 203, 204, 205, 206, 207, 208, 213, 214, 215, 218, 219, 220, 221, 223, 225, 226, 227, 228, 230(1), 230(2), 231, 232, and 405. Examples of yellow pigments include Yellow 4, 5, 201, 202(1), 202(2), 203, 204, 205, 401, 402, 403, 404, 405, 406, and 407. Examples of green pigments include Green Nos. 3, 201, 202, 204, 205, 401, and 402. Examples of blue pigments include Blue Nos. 1, 2, 201, 202, 203, 204, 205, 403, and 404. Examples of orange pigments include Orange Nos. 201, 203, 204, 205, 206, 207, 401, 402, and 403. In addition to the above, examples include Brown No. 201, Purple Nos. 201 and 401, and Black No. 401.

[0065] By selecting an organic pigment 31 that exhibits a color close to the interference color of the optical function film 12, the color saturation can be improved by the synergistic effect of the interference color of the optical function film 12 and the color of the organic pigment 31.

[0066] (Resin) In the pigment complex 30, at least a portion of the surface of the organic pigment 31 is covered with the resin 32. The entire surface of the organic pigment 31 may be covered with the resin 32.

[0067] The resin 32 may have a non-polar portion and a polar portion. Such a resin 32 is easily adsorbed to the surface of the organic pigment 31, and therefore the entire surface of the organic pigment 31 is easily covered with the resin 32. Furthermore, such a resin 32 is easily dispersed in an aqueous medium, and therefore a second film 22 containing silica as a main component is easily formed on the surface of the organic pigment 31 (pigment complex 30) covered with the resin 32, as will be described later in the manufacturing method of the bright pigment 100.

[0068] The resin 32 may contain either a cationic group or an anionic group. Examples of resins containing cationic groups include cationic group-containing organic polymer compounds obtained by copolymerizing cationic group-containing monomers containing amino groups, quaternary ammonium salt groups, or the like with other monomers copolymerizable with these cationic group-containing monomers. Examples of resins containing anionic groups include anionic group-containing organic polymer compounds obtained by copolymerizing anionic group-containing monomers containing carboxyl groups, sulfonic groups, phosphonic groups, thiocarboxyl groups, or the like with other monomers copolymerizable with these anionic group-containing monomers. Considering the availability and cost of raw material monomers, anionic group-containing organic polymer compounds containing carboxyl groups or sulfonic groups are preferred. Anionic group-containing organic polymer compounds containing carboxyl groups are particularly preferred because they allow for a wide range of control over the coexistence of electrically neutral and anionic states.

[0069] Examples of monomers containing a carboxyl group that can be used in the synthesis of anionic group-containing organic polymer compounds include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, and 4-vinylbenzoic acid; and unsaturated polybasic acid esters such as vinyl succinate, allyl maleate, vinyl terephthalate, and allyl trimellitate. Examples of monomers containing a sulfonic acid group include unsaturated carboxylic acid sulfo-substituted alkyl or aryl esters such as 2-sulfoethyl acrylate and 4-sulfophenyl methacrylate; unsaturated sulfocarboxylic acid esters such as vinyl sulfosuccinate; and sulfostyrenes such as styrene-4-sulfonic acid.

[0070] Other monomers copolymerizable with the anionic group-containing monomer that can be used in the synthesis of an anionic group-containing organic polymer compound include, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, isobornyl acrylate, benzyl acrylate, 2,3-epoxypropyl acrylate, 2,3-epoxybutyl acrylate, 2,3-epoxycyclohexyl acrylate, vinyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate. Unsaturated fatty acid esters such as octadecyl, cyclohexyl methacrylate, isobornyl methacrylate, benzyl methacrylate, 2,3-epoxypropyl methacrylate, 2,3-epoxybutyl methacrylate, 2,3-epoxycyclohexyl methacrylate, vinyl methacrylate, dimethyl maleate, diethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl itaconate, benzyl itaconate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-aminoethyl acrylate, 2-aminopropyl acrylate, 3-aminopropyl acrylate, 2-(methylamino)ethyl acrylate, 2-(methylamino)propyl acrylate, 2-(ethylamino)ethyl acrylate, 2-(ethylamino)propyl acrylate, 2-(dimethylamino)ethyl acrylate, and 3-(dimethylamino)propyl acrylate;Acrylamide, N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, N-dimethylacrylamide, N-diethylacrylamide, N-dipropylacrylamide, N-(2-aminoethyl)acrylamide, N-(2-aminopropyl)acrylamide, N-(3-aminopropyl)acrylamide, N-[2-(methylamino)ethyl]acrylamide, N-[2-(methylamino)propyl]acrylamide, N-[3-(methylamino)propyl]acrylamide, N-[2-(dimethylamino)ethyl]acrylamide N-(2-(dimethylamino)propyl)acrylamide, N-[2-(dimethylamino)propyl]acrylamide, N-[3-(dimethylamino)propyl]acrylamide, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, N-propylmethacrylamide, N-dimethylmethacrylamide, N-diethylmethacrylamide, N-dipropylmethacrylamide, N-(2-aminoethyl)methacrylamide, N-(2-aminopropyl)methacrylamide, N-(3-aminopropyl)methacrylamide, N-[ unsaturated fatty acid amides such as N-[2-(methylamino)ethyl]methacrylamide, N-[2-(methylamino)propyl]methacrylamide, N-[3-(methylamino)propyl]methacrylamide, N-[2-(dimethylamino)ethyl]methacrylamide, N-[2-(dimethylamino)propyl]methacrylamide, N-[3-(dimethylamino)propyl]methacrylamide, maleamide, N,N-dimethylmaleamide, fumaramide, N,N-dimethylfumaramide; unsaturated nitriles such as acrylonitrile and methacrylonitrile; tolyls; unsaturated carboxylic acid esters such as vinyl acetate, vinyl propionate, vinyl butanoate, vinyl hexanoate, vinyl 2-ethylhexanoate, vinyl octadecanoate, vinyl benzoate, allyl acetate, allyl propionate, allyl hexanoate, and allyl decanoate; unsaturated ethers such as ethyl vinyl ether and butyl vinyl ether; styrenes such as styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-t-butylstyrene, 4-methoxystyrene, and 4-chlorostyrene;Examples of the unsaturated hydrocarbons include ethylene, propylene, 1-butene, 1-octene, vinylcyclohexane, and 4-vinylcyclohexene; unsaturated halogenated hydrocarbons such as vinyl chloride, vinylidene chloride, tetrafluoroethylene, and 3-chloropropylene; vinyl-substituted heterocyclic compounds such as 4-vinylpyridine, N-vinylcarbazole, and N-vinylpyrrolidone; reaction products of the above-exemplified monomers containing a substituent having active hydrogen, such as a carboxyl group, a hydroxyl group, or an amino group, with epoxides such as ethylene oxide, propylene oxide, and cyclohexene oxide; and reaction products of the above-exemplified monomers containing a substituent having a hydroxyl group, an amino group, or the like, with carboxylic acids such as acetic acid, propionic acid, butanoic acid, hexanoic acid, decanoic acid, and dodecanoic acid.

[0071] As the anionic group-containing organic polymer compound, for example, a styrene-acrylic acid copolymer is preferably used. In addition to the styrene-based monomer, the acrylic acid monomer, and the methacrylic acid monomer, known monomers copolymerizable with these monomers may be copolymerized into the styrene-acrylic acid copolymer. Examples of such monomers include acrylic acid esters and methacrylic acid esters such as methyl acrylate, methyl methacrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, tert-butyl acrylate, 2-ethylbutyl acrylate, 1,3-dimethylbutyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, ethyl methacrylate, n-butyl methacrylate, 2-methylbutyl methacrylate, pentyl methacrylate, heptyl methacrylate, and nonyl methacrylate; 3-ethoxypropyl acrylate, 3-ethoxybutyl acrylate, dimethylaminoethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl acrylate, and 2-hydroxyethyl acrylate. Examples of the monomer include acrylic acid ester derivatives and methacrylic acid ester derivatives such as hydroxybutyl acrylate, ethyl-α-(hydroxymethyl)acrylate, dimethylaminoethyl methacrylate, hydroxyethyl methacrylate, and hydroxypropyl methacrylate; aryl acrylate esters and aralkyl acrylate esters such as phenyl acrylate, benzyl acrylate, phenylethyl acrylate, and phenylethyl methacrylate; monoacrylic acid esters or monomethacrylic acid esters of polyhydric alcohols such as diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, and bisphenol A; dialkyl maleates such as dimethyl maleate and diethyl maleate; and vinyl acetate. These monomers can be added singly or in combination as the monomer component.

[0072] The anionic group-containing organic polymer compound can be synthesized by various known reaction methods such as bulk polymerization, solution polymerization, suspension polymerization, emulsion polymerization, etc. For example, examples of polymerization catalysts used in the synthesis of styrene-acrylic acid copolymers include 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), benzoyl peroxide, dibutyl peroxide, and butyl peroxybenzoate.

[0073] The styrene-acrylic acid copolymer may be a random copolymer or a graft copolymer. An example of a graft copolymer is a graft copolymer in which a copolymer of styrene and a nonionic monomer copolymerizable with polystyrene or styrene serves as the trunk or branch, and a copolymer of acrylic acid, methacrylic acid, and another monomer including styrene serves as the branch or trunk. The styrene-acrylic acid copolymer may be a mixture of this graft copolymer and a random copolymer.

[0074] The content of organic pigment 31 in pigment complex 30 is preferably greater than the content of resin 32. The ratio of the content of organic pigment 31 to the content of resin 32 may be, for example, within a range of 60%:40% by mass to 90%:10% by mass. The ratio of the content of organic pigment 31 to the content of resin 32 is preferably 80%:20% by mass. In this specification, the content of organic pigment 31 and the content of resin 32 in pigment complex 30 can be determined, for example, from the amounts charged.

[0075] The content ratio of the pigment complex 30 relative to the mass of the glittering substrate 10 may be within the range of 0.1 to 15% by mass, and may further be within the range of 0.5 to 10% by mass. More specifically, the content ratio of the pigment complex 30 relative to the mass of the glittering substrate 10 is preferably within the range of 0.1 to 5% by mass, and more preferably within the range of 0.5 to 2% by mass. By keeping the content ratio of the pigment complex 30 within the above range, a decrease in reflectance on the surface of the glittering substrate 10 due to absorption by the organic pigment 31 is suppressed, and therefore a decrease in the glitteriness of the glittering pigment 100 is suppressed. In this specification, the content ratio of the pigment complex 30 relative to the mass of the glittering substrate 10 can be determined, for example, from the charge amount.

[0076] For example, the pigment complex 30 can be produced by the method described below. First, a mixture containing an organic pigment 31 and a resin 32 is dispersed in an aqueous medium to obtain an aqueous pigment dispersion. In the aqueous pigment dispersion, the resin 32 is disposed on at least a portion of the surface of the organic pigment 31. That is, the pigment complex 30 is formed in the aqueous pigment dispersion. The resin 32 may be disposed so as to cover the entire surface of the organic pigment 31.

[0077] The aqueous medium is a solvent in which the resin 32 can be dispersed. Examples of the aqueous medium include water, organic solvents miscible with water, and mixtures of water and organic solvents miscible with water. Examples of organic solvents miscible with water include alcohols such as methanol, ethanol, n- and isopropanol; ketones such as acetone and methyl ethyl ketone; polyalkylene glycols such as ethylene glycol, diethylene glycol, and propylene glycol; alkyl ethers of polyalkylene glycol; and lactams such as N-methyl-2-pyrrolidone. Considering safety and the burden on the environment, it is preferable to use only water or a mixture of water and an organic solvent miscible with water as the aqueous medium, and it is particularly preferable to use only water.

[0078] When the resin 32 is an anionic group-containing organic polymer compound, the weight-average molecular weight of the anionic group-containing organic polymer compound is preferably in the range of 2,000 to 100,000, and more preferably in the range of 5,000 to 50,000. A weight-average molecular weight of 2,000 or more improves the dispersion stability of the aqueous pigment dispersion itself, making it less likely for the organic pigment 31 to settle in the aqueous pigment dispersion due to aggregation or the like. A weight-average molecular weight of 100,000 or less suppresses an increase in the viscosity of the aqueous pigment dispersion, thereby increasing dispersibility. In this specification, the weight-average molecular weight is a value measured by GPC (gel permeation chromatography) and converted into the molecular weight of polystyrene used as a standard substance.

[0079] When a styrene-acrylic acid copolymer is used as the resin 32, the weight average molecular weight of the styrene-acrylic acid copolymer is preferably in the range of 5,000 to 20,000, more preferably in the range of 5,000 to 18,000, and even more preferably in the range of 5,500 to 15,000.

[0080] When the resin 32 is an anionic group-containing organic polymer compound, the acid value of the anionic group-containing organic polymer compound is preferably in the range of 30 to 220 mgKOH / g. An acid value of 30 mgKOH / g or higher ensures sufficient hydrophilicity, which tends to improve the dispersion stability of the organic pigment 31 in the aqueous pigment dispersion. An acid value of 220 mgKOH / g or lower tends to make aggregation of the organic pigment 31 less likely to occur in the aqueous pigment dispersion. In this specification, the acid value is a value measured in accordance with Japanese Industrial Standards "JIS K 0070:1992 Testing Methods for Acid Value, Saponification Value, Ester Value, Iodine Value, Hydroxyl Value, and Unsaponifiable Matter of Chemical Products," and is the amount (mg) of potassium hydroxide required to completely neutralize 1 g of resin.

[0081] When a styrene-acrylic acid copolymer is used as the resin 32, the styrene-acrylic acid copolymer has carboxyl groups derived from acrylic acid monomers and methacrylic acid monomers, and the acid value is preferably in the range of 120 to 220 mgKOH / g, and more preferably in the range of 150 to 200 mgKOH / g.

[0082] When resin 32 is an anionic group-containing organic polymer compound, the glass transition point of the anionic group-containing organic polymer compound is preferably within the range of −20 to 100° C. Having a glass transition point within the above range can improve the abrasion resistance and other properties of pigment complex 30.

[0083] In the aqueous pigment dispersion, it is preferable for the anionic group-containing organic polymer compound used as the resin 32 to have at least a portion of the anionic groups ionized by a basic substance in order to achieve dispersibility and dispersion stability. The optimal proportion of ionized groups among the anionic groups is not uniquely limited, as it varies depending on the composition, molecular weight, acid value, etc., of the anionic group-containing organic polymer compound used. However, it is sufficient as long as the desired dispersibility and dispersion stability are achieved. It is generally preferable to set the proportion of ionized groups within the range of 30 to 100%, and particularly within the range of 70 to 100%. Note that this proportion of ionized groups does not refer to the molar ratio of anionic groups to basic substances, but rather takes dissociation equilibrium into consideration. For example, if the anionic groups are carboxyl groups, even when a stoichiometrically equivalent amount of a strong basic substance is used, the proportion of ionized groups due to dissociation equilibrium will be less than 100%, and the anionic groups of the neutralized anionic group-containing organic polymer compound will be a mixture of carboxylate groups and carboxyl groups.

[0084] Examples of basic substances used to neutralize and ionize at least a portion of the anionic groups in an anionic group-containing organic polymeric compound include known and commonly used substances, and preferred examples include compounds selected from the group consisting of ammonia, primary, secondary, or tertiary organic amines (including basic nitrogen-containing heterocyclic compounds), and alkali metal hydroxides. By ionizing at least a portion of the anionic groups with these preferred basic substances, the counter ions of the carboxylate groups become cations selected from the group consisting of ammonium ions (including protonated cations of basic nitrogen-containing heterocyclic compounds) and alkali metal ions.

[0085] The ratio of the organic pigment 31 to the resin 32 in the aqueous pigment dispersion is preferably 10 to 200 parts by mass per 100 parts. If the ratio of the resin 32 is too low, the abrasion resistance of the pigment complex 30 tends to decrease, and if the ratio of the resin 32 is too high, the viscosity of the dispersion tends to increase.

[0086] [Method for producing the bright pigment] Next, a method for producing the bright pigment 100 of the present embodiment described above will be described.

[0087] The method for producing the glittering pigment 100 in this embodiment includes treating the surface of the glittering substrate 10 with a first surface treatment agent containing a silane coupling agent to form a first film 21 containing the silane coupling agent on at least a portion of the surface of the glittering substrate 10 (step S1); and preparing an aqueous dispersion containing a pigment complex 30 containing an organic pigment 31 and a resin 32 covering at least a portion of the surface of the organic pigment 31, and the glittering substrate 10 on which the first film 21 has been formed, and adhering the pigment complex 30 to the surface of the first film 21 (step S2).

[0088] When the glittering substrate 10 includes a flaky substrate 11 and an optical functional film 12 formed on at least a part of the surface of the flaky substrate 11, the manufacturing method may include, before step S1, forming an optical functional film 21 on at least a part of the surface of the flaky substrate 11. The method for forming the optical functional film 21 on at least a part of the surface of the flaky substrate 11 is as described above.

[0089] In step S1, the surface of the glittering substrate 10 is treated with a first surface treatment agent to form a first film 21 containing a silane coupling agent on the surface of the glittering substrate 10. The first film 21 is formed so as to cover at least a portion of the surface of the glittering substrate 10. The first film 21 may also be formed so as to cover the entire surface of the glittering substrate 10.

[0090] For example, in step S1, a silane coupling agent is added to pure water and stirred at room temperature to hydrolyze the silane coupling agent, thereby obtaining a first surface treatment agent. Next, the glittering substrate 10 is added to the pure water and stirred, and then the first surface treatment agent is added and further stirred. The resulting mixture is filtered and then dried. This allows a first film 21 containing the silane coupling agent to be formed on at least a portion of the surface of the glittering substrate 10.

[0091] For convenience, in this embodiment, the aqueous dispersion containing the pigment complex 30 and the glittering substrate 10 on which the first film 21 is formed is referred to as a first aqueous dispersion. In step S2, a first aqueous dispersion containing the pigment complex 30 and the glittering substrate 10 on which the first film 21 is formed is prepared, and the pigment complex 30 is attached to the surface of the first film 21. Step S2 is performed, for example, by a sol-gel method.

[0092] Step S2 may include disposing a resin 32 on at least a portion of the surface of the organic pigment 31 to prepare a pigment complex 30. The method for preparing the pigment complex 30 is as described above.

[0093] In step S2, the aqueous dispersion may further contain a second surface treatment agent containing a hydrolyzable compound containing a silicon atom or a hydrolysate of the compound, and step S2 may include attaching the pigment complex 30 to the surface of the first film 21 and forming a second film 22 containing silica as a main component on at least a portion of the surface of the pigment complex 30, or on at least a portion of the surface of the pigment complex 30 and at least a portion of the surface of the first film 21.

[0094] When the aqueous dispersion further contains a second surface treatment agent, for example, a second film 22 containing silica as a main component can be formed on at least a portion of the surface of the pigment complex 30, or on at least a portion of the surface of the pigment complex 30 and at least a portion of the surface of the first film 21, by hydrolysis and condensation polymerization of a hydrolyzable compound containing a silicon atom.

[0095] For convenience, in this embodiment, the aqueous dispersion further containing a second surface treatment agent is referred to as the second aqueous dispersion. The second aqueous dispersion may contain, for example, 0.1 to 20 mass% of a hydrolyzable compound containing silicon atoms and 0.1 to 5 mass% of an organic pigment 31. The second aqueous dispersion may further contain water for hydrolysis. For example, the mixing ratio (molar ratio) of silicon alkoxide, which is a hydrolyzable compound containing silicon atoms, to water is preferably 25 to 100 parts by weight, where silicon alkoxide is taken as 1 part by weight. By changing the content ratio of the hydrolyzable compound containing silicon atoms and the organic pigment 31, the content ratio of silica and the organic pigment 31 finally contained in the second film 22 can be controlled.

[0096] The second aqueous dispersion may further contain a solvent. Examples of such a solvent include organic solvents such as hydrocarbons such as hexane, toluene, and cyclohexane; halogenated hydrocarbons such as methyl chloride, carbon tetrachloride, and trichloroethylene; ketones such as acetone and methyl ethyl ketone; nitrogen-containing compounds such as diethylamine; alcohols; and esters such as ethyl acetate. Among these, alcohol-based solvents are preferably used, such as methyl alcohol, ethyl alcohol, 1-propyl alcohol, 2-propyl alcohol, butyl alcohol, and amyl alcohol. Acyclic saturated monohydric alcohols having 3 or less carbon atoms, such as methyl alcohol, ethyl alcohol, 1-propyl alcohol, and 2-propyl alcohol, are particularly preferably used because of their high evaporation rate at room temperature.

[0097] The second aqueous dispersion may further contain a catalyst. Suitable catalysts include alkaline catalysts such as ammonium hydroxide, ammonia, and sodium hydroxide. In this case, the pH of the second aqueous dispersion is usually within the range of 10 to 14.

[0098] For example, in step S2, 1 to 20% by mass of the glittering substrate 10 is dispersed in the second aqueous dispersion, and the dispersion is stirred for 2 to 3 hours to hydrolyze and polycondense the silicon-containing hydrolyzable compound. This allows the second film 22 containing the pigment complex 30 to be formed on the surface of the glittering substrate 10. The resulting mixture is then washed with water, filtered, and dried. The drying is preferably carried out at a temperature of 120 to 180°C. The drying time can be appropriately set depending on the amount of material charged.

[0099] According to the method for producing the bright pigment 100 of this embodiment, it is possible to produce the bright pigment 100 with an improved effect of suppressing pigment shedding.

[0100] The bright pigment 100 of this embodiment can be used, for example, as a coating composition. The bright pigment 100 of this embodiment is such that the organic pigment 31 is not easily shed even when stirred with a coating material for a long period of time, thereby improving the appearance of the resulting coating composition.

[0101] The present invention will be described in more detail below using examples, but the present invention is not limited to the following examples.

[0102] [Example 1] <Glittering substrate> A glass flake coated with a rutile-type titanium oxide film exhibiting a blue interference color (ST1025RB, manufactured by Nippon Sheet Glass Co., Ltd.) was used as the glittering substrate. The glittering substrate had a thickness of 1.3 μm and an average particle size of 25 μm.

[0103] <First Surface Treatment> Diethoxydimethylsilane was used as the silane coupling agent. 0.3 g of diethoxydimethylsilane was added to 20 mL of pure water and then stirred at room temperature for 30 minutes to allow hydrolysis. This resulted in a first surface treatment agent. 30 g of glittering substrate was added to 300 mL of pure water and stirred with a stirrer, after which the first surface treatment agent was further added and stirred for 15 minutes. The resulting mixture was filtered and then dried at 120°C for 4 hours. In this way, a first film containing a silane coupling agent was formed on the surface of the glittering substrate.

[0104] <Second Surface Treatment> Tetraethoxysilane was used as the silicon-containing hydrolyzable compound. 10 mL of tetraethoxysilane and 300 mL of isopropyl alcohol were mixed to obtain a second surface treatment agent. 2 g of an aqueous pigment dispersion (DIC Corporation, FG CYAN 1SL, average particle size: approximately 100 nm, solid content: 18%, blue pigment / resin weight ratio 80 / 20, blue pigment: phthalocyanine pigment, resin: styrene / acrylic copolymer) was added to the second surface treatment agent as a dispersion containing a pigment complex, and further mixed to obtain a mixed solution. The glittering substrate on which the first film had been formed was added to the mixed solution, and 10 mL of ammonium hydroxide solution (concentration 25%) was further added to obtain an aqueous dispersion. The aqueous dispersion was stirred and mixed for 2 to 3 hours to allow a dehydration condensation reaction to occur. This resulted in the pigment complex adhering to the surface of the first film in the aqueous dispersion. The pigment complex contained an organic pigment and a resin covering the surface of the organic pigment. It is presumed that in the aqueous dispersion, a second film containing silica as a main component was formed on the surface of the pigment complex, and at the same time, the pigment complex on which the second film was formed adhered to the first film, and a second film was further formed on top of that. In this way, the pigment complex was firmly adhered to the surface of the glittering substrate on which the first film was formed.

[0105] Subsequently, the aqueous dispersion was filtered and washed with water several times, then dried, and finally subjected to heat treatment at 150° C. for 2 hours. This yielded the bright pigment of Example 1. The bright pigment of Example 1 exhibited a lustrous blue color.

[0106] [Example 2] <Glittering substrate> A glass flake coated with a rutile-type titanium oxide film exhibiting a silver interference color (ST1025RS, manufactured by Nippon Sheet Glass Co., Ltd.) was used as the glittering substrate. The glittering substrate had a thickness of 1.3 μm and an average particle size of 25 μm.

[0107] <First Surface Treatment> Using the same method as in Example 1, a first film containing a silane coupling agent was formed on the surface of the glittering substrate.

[0108] <Second Surface Treatment> Using the same method as in Example 1, the pigment complex was firmly attached to the surface of the glittering substrate on which the first film had been formed.

[0109] Subsequently, the aqueous dispersion was filtered and washed with water several times in the same manner as in Example 1, and then dried, and finally subjected to heat treatment at 150°C for 2 hours. This yielded the bright pigment of Example 2. The bright pigment of Example 2 exhibited a lustrous blue color.

[0110] [Example 3] <Glittering substrate> A glass flake coated with a rutile-type titanium oxide film exhibiting a blue interference color (ST1022RB, manufactured by Nippon Sheet Glass Co., Ltd.) was used as the glittering substrate. The glittering substrate had a thickness of 1.3 μm and an average particle size of 22 μm.

[0111] <First Surface Treatment> Using the same method as in Example 1, a first film containing a silane coupling agent was formed on the surface of the glittering substrate.

[0112] <Second Surface Treatment> The second surface treatment agent obtained in Example 1 was used as the second surface treatment agent. 2 g of an aqueous pigment dispersion (eXpand! Blue ST6001, manufactured by DIC Corporation, average particle size: approximately 80 nm, solid content: 28 wt %, blue pigment / resin weight ratio: 60 / 40, blue pigment: indanthrone pigment, resin: styrene / maleic anhydride copolymer, etc.) was used as a dispersion containing a pigment complex to be added to the second surface treatment agent. Except for this, the pigment complex was firmly adhered to the surface of the glittering substrate on which the first film had been formed, using the same method as in Example 1.

[0113] Subsequently, the aqueous dispersion was filtered and washed with water several times in the same manner as in Example 1, and then dried, and finally subjected to heat treatment at 150°C for 2 hours. This yielded the bright pigment of Example 3. The bright pigment of Example 3 exhibited a lustrous blue color.

[0114] [Example 4] <Glittering substrate> A glass flake coated with a rutile-type titanium oxide film exhibiting a yellow interference color (ST1022RY, manufactured by Nippon Sheet Glass Co., Ltd.) was used as the glittering substrate. The glittering substrate had a thickness of 1.3 μm and an average particle size of 22 μm.

[0115] <First Surface Treatment> Using the same method as in Example 1, a first film containing a silane coupling agent was formed on the surface of the glittering substrate.

[0116] <Second Surface Treatment> The second surface treatment agent obtained in Example 1 was used as the second surface treatment agent. 2 g of an aqueous pigment dispersion (eXpand! Ylw ST1018, manufactured by DIC Corporation, average particle size: approximately 70 nm, solid content concentration: 34 wt %, yellow pigment / resin weight ratio: 50 / 50, yellow pigment: isoindolinone pigment, resin: styrene / maleic anhydride copolymer) was used as a dispersion containing a pigment complex to be added to the second surface treatment agent. Except for this, the pigment complex was firmly adhered to the surface of the glittering substrate on which the first film had been formed using the same method as in Example 1.

[0117] Subsequently, the aqueous dispersion was filtered and washed with water several times in the same manner as in Example 1, and then dried, and finally subjected to heat treatment at 150°C for 2 hours. This yielded the bright pigment of Example 4. The bright pigment of Example 4 exhibited a glossy yellow color.

[0118] [Example 5] <Glittering substrate> A glass flake coated with a rutile-type titanium oxide film exhibiting a red interference color (ST1022RR, manufactured by Nippon Sheet Glass Co., Ltd.) was used as the glittering substrate. The glittering substrate had a thickness of 1.3 μm and an average particle size of 22 μm.

[0119] <First Surface Treatment> Using the same method as in Example 1, a first film containing a silane coupling agent was formed on the surface of the glittering substrate.

[0120] <Second Surface Treatment> The second surface treatment agent obtained in Example 1 was used as the second surface treatment agent. 2 g of an aqueous pigment dispersion (eXpand! Red EH3427, manufactured by DIC Corporation, average particle size: approximately 100 nm, solid content concentration: 28 wt %, red pigment / resin weight ratio: 75 / 25, red pigment: perylene pigment, resin: styrene / acrylic acid copolymer) was used as a dispersion containing a pigment complex to be added to the second surface treatment agent. Except for this, the pigment complex was firmly adhered to the surface of the glittering substrate on which the first film had been formed using the same method as in Example 1.

[0121] Subsequently, the aqueous dispersion was filtered and washed with water several times in the same manner as in Example 1, and then dried, and finally subjected to heat treatment at 150°C for 2 hours. This yielded the bright pigment of Example 5. The bright pigment of Example 5 exhibited a glossy red color.

[0122] Comparative Example 1 <Glittering Substrate> As in Example 1, flake glass coated with a rutile-type titanium oxide film exhibiting a blue interference color (manufactured by Nippon Sheet Glass Co., Ltd., ST1025RB) was used as the glittering substrate.

[0123] <First Surface Treatment> Using the same method as in Example 1, a first film containing a silane coupling agent was formed on the surface of the glittering substrate.

[0124] <Second Surface Treatment> Tetraethoxysilane was used as the silicon-containing hydrolyzable compound. 10 mL of tetraethoxysilane and 300 mL of isopropyl alcohol were mixed to obtain a second surface treatment agent. 0.75 g of a solution containing 40% by mass of blue organic pigment (EMF BLUE HG, manufactured by Toyo Ink Co., Ltd.) fine particles (average particle size: 40 nm) was further added to the second surface treatment agent and mixed to obtain a mixed solution. The glittering substrate on which the first film was formed was added to the mixed solution, and 10 mL of ammonium hydroxide solution (concentration: 25%) was further added to obtain an aqueous dispersion. The aqueous dispersion was stirred and mixed for 2 to 3 hours to cause a dehydration condensation reaction. As a result, the organic pigment fine particles adhered to the surface of the first film in the aqueous dispersion. In this way, the organic pigment fine particles were adhered to the surface of the glittering substrate on which the first film was formed.

[0125] Subsequently, the aqueous dispersion was filtered and washed with water several times in the same manner as in Example 1, and then dried, and finally subjected to heat treatment at 150°C for 2 hours. This yielded the bright pigment of Comparative Example 1. The bright pigment of Comparative Example 1 exhibited a lustrous blue color.

[0126] [Comparative Example 2] <Glittering substrate> As the glittering substrate, glass flakes (ST1025RB, manufactured by Nippon Sheet Glass Co., Ltd.) coated with a rutile-type titanium oxide film exhibiting a blue interference color were used, as in Example 1. In Comparative Example 2, the first surface treatment was not performed. That is, the first film was not formed on the surface of the glittering substrate.

[0127] <Second Surface Treatment> Using the same method as in Example 1, an organic pigment composition was adhered to the surface of the glittering substrate on which no first film had been formed.

[0128] Subsequently, the aqueous dispersion was filtered and washed with water several times in the same manner as in Example 1, and then dried, and finally subjected to heat treatment at 150°C for 2 hours. This yielded the bright pigment of Comparative Example 2. The bright pigment of Comparative Example 2 exhibited a lustrous blue color.

[0129] [Comparative Example 3] <Glittering substrate> A glass flake coated with a rutile-type titanium oxide film exhibiting a blue interference color (ST1022RB, manufactured by Nippon Sheet Glass Co., Ltd.) was used as the glittering substrate. In Comparative Example 3, the first surface treatment was not performed. That is, the first film was not formed on the surface of the glittering substrate.

[0130] <Second Surface Treatment> Using the same method as in Example 3, an organic pigment composition was adhered to the surface of the glittering substrate on which no first film had been formed.

[0131] Subsequently, the aqueous dispersion was filtered and washed with water several times in the same manner as in Example 1, and then dried, and finally subjected to heat treatment at 150°C for 2 hours. This yielded the bright pigment of Comparative Example 3. The bright pigment of Comparative Example 3 exhibited a lustrous blue color.

[0132] [Comparative Example 4] <Glittering substrate> A glass flake coated with a rutile-type titanium oxide film exhibiting a yellow interference color (ST1022RY, manufactured by Nippon Sheet Glass Co., Ltd.) was used as the glittering substrate. In Comparative Example 4, the first surface treatment was not performed. That is, the first film was not formed on the surface of the glittering substrate.

[0133] <Second Surface Treatment> Using the same method as in Example 4, an organic pigment composition was adhered to the surface of the glittering substrate on which no first film had been formed.

[0134] Subsequently, the aqueous dispersion was filtered and washed with water several times in the same manner as in Example 1, and then dried, and finally subjected to heat treatment at 150°C for 2 hours. This yielded the bright pigment of Comparative Example 4. The bright pigment of Comparative Example 4 exhibited a glossy yellow color.

[0135] [Comparative Example 5] <Glittering substrate> A glass flake coated with a rutile-type titanium oxide film exhibiting a red interference color (ST1022RR, manufactured by Nippon Sheet Glass Co., Ltd.) was used as the glittering substrate. In Comparative Example 5, the first surface treatment was not performed. That is, the first film was not formed on the surface of the glittering substrate.

[0136] <Second Surface Treatment> Using the same method as in Example 5, an organic pigment composition was adhered to the surface of the glittering substrate on which no first film had been formed.

[0137] Subsequently, the aqueous dispersion was filtered and washed with water several times in the same manner as in Example 1, and then dried, and finally subjected to heat treatment at 150°C for 2 hours. This yielded the bright pigment of Comparative Example 5. The bright pigment of Comparative Example 5 exhibited a glossy red color.

[0138] Reference Example 1 The glass flakes (ST1025RB, manufactured by Nippon Sheet Glass Co., Ltd.) coated with a rutile-type titanium oxide film exhibiting a blue interference color, which was used as the glittering substrate in Examples 1 and 2, were used as Reference Example 1.

[0139] Reference Example 3 The glass flakes (ST1022RB, manufactured by Nippon Sheet Glass Co., Ltd.) coated with a rutile-type titanium oxide film exhibiting a blue interference color, which was used as the glittering substrate in Example 3, were used as Reference Example 3.

[0140] Reference Example 4 The glass flakes (ST1022RY, manufactured by Nippon Sheet Glass Co., Ltd.) coated with a rutile-type titanium oxide film exhibiting a yellow interference color, which was used as the glittering substrate in Example 4, were used as Reference Example 4.

[0141] Reference Example 5 The glass flakes (ST1022RR, manufactured by Nippon Sheet Glass Co., Ltd.) coated with a rutile-type titanium oxide film exhibiting a red interference color, which was used as the glittering substrate in Example 5, were used as Reference Example 5.

[0142] <Evaluation of Falling-Off> For each of the obtained effective pigments, the falling-off of the organic pigment was evaluated using the following method. 1 g of effective pigment and 20 mL of isopropyl alcohol were placed in a 50 mL glass bottle. A stirrer was placed in the glass bottle, and the mixture was stirred at 600 rpm for 24 hours using a magnetic stirrer. After stirring was stopped, the mixture was left to stand for 1 hour to allow the effective pigment to settle, and then the supernatant was removed. The light transmittance (%) of the supernatant was measured at wavelengths of 480 nm, 580 nm, and 680 nm using an ultraviolet-visible-near-infrared spectrophotometer (Shimadzu Corporation, UV-3600). A 10 mm wide cell was used for the measurement. The results are shown in Tables 1 to 4.

[0143] <Color Measurement> The resulting luster pigments were subjected to color measurement, i.e., evaluation of luster and particle appearance, using the following method. 1 g of the luster pigment was added to 9 g of acrylic lacquer (Acrylic Super Clear, manufactured by Nippon Paint Co., Ltd.), mixed thoroughly, and applied to black and white opacity measurement paper at a thickness of 9 mils (9 / 1000 inch), respectively, to prepare black and white samples. Both samples were then air-dried at room temperature. Black and white samples were also prepared using the same method for each reference example. Using a multi-angle colorimeter (BYK-mac, manufactured by BYK-Gardner Co., Ltd.), the C* (chroma) of both samples was measured at 15° (highlight), 45°, and 75° (shade) using the CIE 1976 (L*a*b*) color system. The results are shown in Tables 1 to 4.

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[0148] <Results of evaluation of dropout> As can be seen from Table 1, in Examples 1 and 2, the transmittance exceeded 65% at wavelengths of 480 nm, 580 nm, and 680 nm. In contrast, in Comparative Example 1, the transmittance was 1% or less at wavelengths of 480 nm, 580 nm, and 680 nm, and the supernatant was cloudy. In Comparative Example 2, the transmittance was 15% or less at wavelengths of 480 nm, 580 nm, and 680 nm, and the supernatant was cloudy. When compared at each wavelength, the transmittance of Comparative Example 2 was 60 points or more lower than the transmittance of Examples 1 and 2.

[0149] As can be seen from Table 2, in Example 3, the transmittance exceeded 50% at wavelengths of 480 nm, 580 nm, and 680 nm. In contrast, in Comparative Example 3, the transmittance was 30% or less at wavelengths of 480 nm, 580 nm, and 680 nm. When compared at each wavelength, the transmittance of Comparative Example 3 was 30 points or more lower than that of Example 3.

[0150] As can be seen from Table 3, in Example 4, the transmittance exceeded 90% at wavelengths of 480 nm, 580 nm, and 680 nm. In contrast, in Comparative Example 4, the transmittance was 65% or less at wavelengths of 480 nm, 580 nm, and 680 nm. When compared at each wavelength, the transmittance of Comparative Example 4 was 30 points or more lower than that of Example 4.

[0151] As can be seen from Table 4, in Example 5, the transmittance exceeded 60% at wavelengths of 480 nm, 580 nm, and 680 nm. In contrast, in Comparative Example 5, the transmittance was 20% or less at wavelengths of 480 nm, 580 nm, and 680 nm. When compared at each wavelength, the transmittance of Comparative Example 5 was 50 points or more lower than that of Example 5.

[0152] The dropout evaluation results suggest that the organic pigment in the bright pigments of Examples 1 and 2 is less likely to drop out than the bright pigments of Comparative Examples 1 and 2. Furthermore, the results suggest that the organic pigment in the bright pigments of Examples 3 to 5 is less likely to drop out than the bright pigments of Comparative Examples 3 to 5, respectively. In the bright pigments of Examples 1 and 2, the organic pigment was present with a resin disposed on its surface (in the form of a pigment complex). This is presumably because the pigment complex was more likely to be uniformly present near the surface of the first film than in the bright pigment of Comparative Example 2, which used an organic pigment without a resin on its surface, and because the interaction between the resin and the first film facilitated adhesion of the pigment complex to the bright substrate. For the same reasons, it is presumed that the pigment complex was more likely to be uniformly present near the surface of the first film than in the bright pigments of Comparative Examples 3 to 5, respectively, and because the pigment complex was more likely to adhere to the bright substrate. Furthermore, it is presumed that in the bright pigments of Examples 1 and 2, the first film contributed to improving the adhesion between the bright substrate and the second film, and therefore the organic pigment adhered more firmly to the bright substrate than in the bright pigment of Comparative Example 2. For the same reason, it is presumed that in the bright pigments of Examples 3 to 5, the organic pigment adhered more firmly to the bright substrate than in the bright pigments of Comparative Examples 3 to 5, respectively.

[0153] <Color Measurement Results> As can be seen from Table 1, when comparing the saturation (C*) of Reference Example 1 with that of Example 1 and Comparative Examples 1-2, the saturation at 15°, 45°, and 75° was improved for both the black and white background samples in Example 1 and Comparative Examples 1-2 due to the addition of a blue organic pigment. The interference color of Reference Example 1 was less noticeable in the white background sample, resulting in a larger difference between the saturation of Reference Example 1 and that of Examples 1 and Comparative Examples 1-2. On the other hand, Example 2 used a glitter substrate exhibiting a silver interference color, and therefore the silver color of the glitter substrate and the blue color of the organic pigment canceled each other out in the black background sample, resulting in a lower saturation than Reference Example 1. The white background sample of Example 2 had a higher saturation than Reference Example 1 due to the effect of the blue organic pigment, but a lower saturation than Example 1 and Comparative Examples 1-2, which used glitter substrates exhibiting blue interference colors.

[0154] As can be seen from Table 2, when the saturation (C*) of Reference Example 3 is compared with that of Example 3 and Comparative Example 3, the saturation of the black background sample at 45° and 75° was improved in Example 3 and Comparative Example 3 by attaching a blue pigment. At 15° in the black background sample, the saturation was slightly lower than in Reference Example 3, and the improvement in saturation was not as great as in Example 1. In the white background sample, the interference color of Reference Example 3 was not noticeable, so the difference in saturation between Reference Example 3 and those of Example 3 and Comparative Example 3 was large.

[0155] As can be seen from Table 3, when the saturation (C*) of Reference Example 4 is compared with that of Example 4 and Comparative Example 4, the saturation of the black background sample at all angles of 15°, 45°, and 75° in Example 4 and Comparative Example 4 was improved compared to Reference Example 4 due to the addition of a yellow pigment. In the white background sample, the interference color of Reference Example 4 was not noticeable, so the difference between the saturation of Reference Example 4 and that of Example 4 and Comparative Example 4 was large.

[0156] As can be seen from Table 4, when the saturation (C*) of Reference Example 5 is compared with that of Example 5 and Comparative Example 5, the saturation of the black background sample at 45° and 75° was improved in Example 5 and Comparative Example 5 due to the addition of a red pigment. At 15° in the black background sample, the red interference color of the glitter substrate and the red of the organic pigment canceled each other out, resulting in a lower saturation than Reference Example 5. In the white background sample, the interference color of Reference Example 5 was not noticeable, so the difference in saturation between Reference Example 5 and those of Example 5 and Comparative Example 5 was large.

[0157] The color measurement results suggest that by selecting an organic pigment that exhibits a color close to the interference color of the glittering substrate, saturation tends to improve due to the synergistic effect between the interference color of the glittering substrate and the color of the organic pigment. However, there were cases where no improvement in saturation was observed or the interference color of the glittering substrate and the color of the organic pigment canceled each other out, making it difficult to achieve the synergistic effect, so it is considered preferable to select a combination that produces a stronger synergistic effect.

[0158] In the above examples, glass flakes are used as the flake substrate, but it is presumed that the effect of preventing pigment shedding can also be achieved when materials other than glass flakes, such as mica flakes, synthetic mica flakes, flaky silica, flaky alumina, and flaky graphite, are used as the flake substrate.

[0159] The bright pigment of the present invention has an improved effect of suppressing pigment shedding, and is therefore applicable to a variety of uses, such as coating compositions.

Claims

1. A luminescent pigment comprising a luminescent substrate, a first film covering at least a part of the surface of the luminescent substrate and containing a silane coupling agent, and a pigment complex attached to the surface of the first film and including an organic pigment and a resin covering at least a part of the surface of the organic pigment.

2. The luminescent pigment according to claim 1, further comprising a second film containing silica as a main component, the second film covering at least a part of the surface of the pigment complex.

3. The luminescent pigment according to claim 2, wherein the second film covers at least a part of the surface of the first film.

4. The luminescent pigment according to claim 1, wherein the luminescent substrate includes a flaky substrate and an optical functional film formed on at least a part of the surface of the flaky substrate, and the optical functional film has at least one function selected from the group consisting of light reflection and coloring.

5. The luminescent pigment according to claim 4, wherein the optical functional film contains titanium oxide.

6. A method for producing a luminescent pigment, comprising treating the surface of a luminescent substrate with a first surface treatment agent containing a silane coupling agent to form a first film containing the silane coupling agent on at least a part of the surface, preparing an aqueous dispersion including a pigment complex including an organic pigment and a resin covering at least a part of the surface of the organic pigment, and the luminescent substrate on which the first film is formed, and attaching the pigment complex to the surface of the first film.

7. The method for producing a luminescent pigment according to claim 6, wherein the aqueous dispersion further contains a second surface treatment agent containing a hydrolyzable compound containing a silicon atom or a hydrolyzate of the compound, and attaching the pigment complex to the surface of the first film and forming a second film containing silica as a main component on at least a part of the surface of the pigment complex, or on at least a part of the surface of the pigment complex and at least a part of the surface of the first film.

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