JP2009215384A - Black pigment and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inorganic black pigment which has a sufficient black degree, is also excellent in thermal stability and heat resistance, and has no causes for concerns about safety and environmental problems; and to provide a black pigment which has a sufficient ability to shield near infrared rays. <P>SOLUTION: The black pigment is prepared by forming a solid solution with 0.05-5 mol% of at least one element selected from among Mg, Mn and Zn in composite oxides containing Ca and Fe. This black pigment has a black degree (L<SP>*</SP>value) of 30 or less and a solar reflectance of 10% or more in wavelengths ranging from 700 to 2,100 nm, so that the black pigment has the sufficient black degree and the sufficient ability to shield near infrared rays. This black pigment is manufactured by mixing calcium and iron compounds with a compound containing at least one element selected from among Mg, Mn and Zn and firing the mixture. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an inorganic complex oxide black pigment mainly composed of Ca and Fe and a method for producing the same. Moreover, it is related with the coating material and resin composition containing the black pigment, and also the black material and near-infrared shielding material using the said coating material.

Inorganic black pigments are used in various fields such as paints, plastics, ceramics, inks and electronic materials, and are important pigments as colorants. Further, black pigments having the ability to reflect near-infrared rays have been attracting attention in recent years as near-infrared shielding pigments because they are used to alleviate the heat island phenomenon and increase the cooling efficiency in summer.
Examples of the black pigment include carbon black, magnetite, low-order titanium oxide, titanium nitride, etc., as well as Cr ₂ O ₃ , Cu—Cr composite oxide, Fe—Cr composite oxide, Co—Fe—Cr composite oxide, What contains chromium, such as Cu-Cr-Mn complex oxide, is known (refer to patent documents 1). On the other hand, the black pigment not containing chromium contains strontium iron oxide (see Patent Document 2), Fe and Co, and is further selected from Mg, Ca, Sr, Ba, Ti, Zn and Cu. A composite oxide containing the above metal (see Patent Document 3) is known.

JP 2000-72990 A JP 2000-264639 A JP 2006-249411 A

  Carbon black, which is widely used as a black pigment, has a carcinogenic problem, and magnetite, low-order titanium oxide, and titanium nitride oxidize even at low temperatures, and the thermal stability problem that blackness decreases accordingly is pointed out Has been. Many complex oxide black pigments contain Cu, Cr, Co, etc. as heavy metals, but there is a strong tendency to refrain from using pigments containing such heavy metals. In particular, due to concerns about the safety of Cr, there is an urgent need to develop black pigments that do not use Cr, and black pigments that do not use expensive raw materials such as Co and Sr are desired.

  As a result of the development of the chromium-free black pigment, the present inventors have developed at least one element selected from Mg, Mn and Zn in a composite oxide containing Ca and Fe, which has been used as a red pigment. It has been found that blackening can be achieved when 0.05 to 5 mol% is dissolved. Moreover, it discovered that the said black pigment has sufficient near-infrared shielding ability, and can be used also for a near-infrared shielding application. Furthermore, it can be manufactured by mixing and baking a calcium compound, an iron compound, and a compound containing at least one element selected from Mg, Mn and Zn, and since the resulting black pigment is powdery, it is a paint The present invention was completed by finding out that it can be blended into a resin composition and used for various purposes.

That is, the present invention is a black pigment obtained by dissolving 0.05 to 5 mol% of at least one element selected from Mg, Mn, and Zn in a composite oxide containing Ca and Fe. Moreover, it is a near infrared shielding black pigment formed by dissolving 0.05 to 5 mol% of at least one element selected from Mg, Mn and Zn in a composite oxide containing Ca and Fe.
In addition, the present invention mixes a calcium compound, an iron compound, and a compound containing at least one element selected from Mg, Mn, and Zn, calcinates them, and adds Mg and Ca to a composite oxide containing Ca and Fe. A method for producing a black pigment, wherein 0.05 to 5 mol% of at least one element selected from Mn and Zn is dissolved.
Moreover, this invention is a coating material and a resin composition which mix | blend the said black pigment, Furthermore, the black material by which the said coating material is apply | coated, a near-infrared shielding material, etc.

The black pigment of the present invention is a complex oxide containing calcium, iron, oxygen and at least one element selected from Mg, Mn and Zn, and is an inorganic black pigment having sufficient blackness. Since it uses a heat-stable inorganic component, it has excellent thermal stability and heat resistance, and does not contain chromium, so there is no concern about safety and environmental problems. In addition, when the solid solution amount of Mg, Mn, and Zn is changed in the range of 0.05 to 5 mol%, the hue such as the blackness changes, so that there is an advantage that fine hue adjustment is easy.
In addition, the black pigment of the present invention has a sufficient near-infrared shielding ability, and can be applied to the roof or outer wall of a building, or applied to a road or a sidewalk to alleviate the heat island phenomenon. Can be used.
And since it can manufacture in air | atmosphere without using an expensive raw material, it can manufacture comparatively cheaply.

The black pigment of the present invention contains 0.05 to at least one element selected from Mg (magnesium), Mn (manganese), and Zn (zinc) in a composite oxide containing Ca (calcium) and Fe (iron). ~ 5 mol% solid solution.
The composite oxide containing Ca and Fe may have any component composition, but calcium ferrite represented by Ca ₂ Fe ₂ O ₅ , CaFe ₂ O ₄ or the like can be used. Ca ₂ Fe ₂ O ₅ is a compound in which the molar ratio of Ca, Fe, and O is 2: 2: 5, and its crystal structure is a brown millerite structure (also referred to as a brown millerite structure). . This brown mirror light structure is a typical example of a structure in which oxygen vacancies in the perovskite structure are increased and oxygen vacancies are ordered at room temperature, and may be represented by CaFeO _2.5 . On the other hand, CaFe ₂ O ₄ has a spinel crystal structure. In the present invention, a compound represented by Ca ₂ Fe ₂ O ₅ having a brown mirror light structure is preferable. When at least one element selected from Mg, Mn and Zn is dissolved, a compound having a desired blackness is obtained. . On the other hand, even if the above elements are dissolved in CaFe ₂ O ₄ , a material excellent in blackness as compared with Ca ₂ Fe ₂ O ₅ cannot be obtained.

In the black pigment of the present invention, the solvent atoms (specifically, Ca and Fe atoms) at the lattice points of the composite oxide containing Ca and Fe are solute atoms (specifically, Mg, Mn, Zn). In the complex oxide particles and / or in the particle surface by forming an interstitial solid solution in which the solute atoms are contained in the lattice gap of the complex oxide. It is thought that solute atoms are in solid solution. The solid solution can be confirmed from the result of X-ray diffraction of the black pigment that no peak of another phase other than the composite oxide appears. In the case where the composite oxide is Ca ₂ Fe ₂ O ₅ , it is presumed that a solid solution in which the above solute atoms are substituted for the solvent atoms of Fe is formed. When expressed as Ca: Fe: O (oxygen): solute atoms = 2: 2-X: 5: X in terms of molar ratio, X is 0.0045 to 0.45.

The solute atoms are at least one element selected from Mg, Mn, and Zn, and other elements such as trivalent elements of Al, B, Y, La, and Bi, tetravalent elements of Si, Ti, and Sn, Even if Mo, W, Nb, and Ta are dissolved, sufficient blackness cannot be obtained. The solid solution amount is important to be 0.05 to 5 mol%, and the degree of blackness is preferably about 30 or less, more preferably 25 or less, expressed by the brightness index L ^* value described later. The solid solution amount is expressed as mol% of solute atoms with respect to the total number of moles of components of Ca, Fe, O (oxygen), and solute atoms. The number of moles of Ca, Fe, and solute atoms is determined by fluorescent X-ray analysis, and the number of moles of O (oxygen) necessary to maintain the charge balance is calculated from the valences of these components.

A composite oxide containing Ca and Fe such as Ca ₂ Fe ₂ O ₅ itself is known as a red pigment, but when the solute atoms are dissolved in this, the color changes from red to black. Can be changed. When the amount of solute atoms is less than 0.05 mol%, blackening is not sufficient, but when it is 0.05 to 5 mol%, it has sufficient blackness and can be used as a black pigment. Blackness is expressed by a lightness index ^{L *} value of ^{CIE 1976 Lab (L * a *} b * color system), indicating that a strong blackness as the ^{L *} value is small in the black pigment. If the solid solution amount is 0.05 mol% or more, the L ^* value tends to have a blackness of about 30 or less, and if the solid solution amount is increased, the L ^* value gradually decreases and the blackness becomes higher. Even if the amount is as small as 5 mol% or less, the L ^* value can be adjusted to a blackness of about 15 to 30, more preferably about 15 to 25. On the other hand, even if an amount exceeding 5 mol% is added, an X-ray diffraction peak of another phase other than the composite oxide appears and a solid solution cannot be generated. A more preferable solid solution amount is 0.1 to 4 mol%, and further preferably 0.5 to 3 mol%. Further, the black pigment of the present invention is preferable because the color becomes darker when absorbing light in the visible range of wavelength 400 to 700 nm, and the spectral reflectance of the visible light is preferably about 10% or less.

Further, L ^* value and is determined in the same manner L ^* a ^* b ^* color system of a ^* value, b ^* value is an index representing the hue saturation and redness as a ^* value increases to the positive side The stronger the negative side, the stronger the green color, and the higher the b ^* value, the stronger the yellowish color and the negative side, the stronger the blue color. In the black pigment of the present invention, redness can be suppressed to, for example, an a ^* value of about 0 to 20, and yellowness can be suppressed to a b ^* value of about −1 to 10.

Moreover, since the black pigment of this invention has sufficient near-infrared shielding ability, it can be used as a near-infrared shielding material. The solute atoms are at least one element selected from Mg, Mn and Zn, preferably Mg and / or Mn elements, and these solute atoms are dissolved in 0.05 to 5 mol%. A composite oxide containing Ca and Fe, such as Ca ₂ Fe ₂ O ₅ , reflects red light and is excellent in near-infrared shielding ability. However, when the above solvent atoms are dissolved in this, The near-infrared shielding ability decreases. However, if the solid solution amount is 0.05 to 5 mol%, sufficient near infrared shielding ability can be maintained. The near-infrared shielding ability is the reflectance of near-infrared rays in the wavelength range of 700 to 2100 nm in sunlight (hereinafter referred to as solar reflectance, which is a weight that expresses the energy distribution of sunlight in the spectral reflectance according to JIS R 3106. It is preferably 10% or more, more preferably 12% or more, still more preferably 15% or more, still more preferably 20% or more, and most preferably 40% or more. In the case of Mg and / or Mn, a more preferable solid solution amount is 0.1 to 4 mol%, and further preferably 0.5 to 3 mol%, in view of the balance between solar reflectance and blackness. In the case of Zn, a more preferable solid solution amount is 0.3 to 2.5 mol%, and further preferably 0.4 to 2 mol%. The spectral reflectance of near infrared rays having a wavelength of 700 to 2100 nm is preferably high because it corresponds to the solar reflectance, and more specifically, about 10% or more is more preferable.

The black pigment of the present invention inevitably contains impurities derived from various raw materials, but Cr is preferably not contained as much as possible, and even if contained as an impurity, it is 1% by weight or less. In particular, the Cr ⁶⁺ content, which is particularly concerned about safety, is preferably 10 ppm or less.

The black pigment of this invention can manufacture what has various particle shapes and particle diameters by changing manufacturing conditions. The particle shape may be, for example, a plate shape, a granular shape, a substantially spherical shape, a needle shape, an indefinite shape, and the like, and the average particle diameter (arithmetic average value of the maximum diameter of one particle) measured from an electron micrograph is 0. The thing of about 0.02-5.0 micrometers is preferable. When the average particle diameter exceeds 5.0 μm, the particle size is too large and the coloring power is reduced. When the average particle size is less than 0.02 μm, dispersion in the paint may be difficult. For this reason, an average particle diameter becomes like this. Preferably it is 0.1-5.0 micrometers, More preferably, it is 0.2-4.5 micrometers, More preferably, it is 0.3-4.0 micrometers. The BET specific surface area value is preferably about 0.1 to 15 m ² / g. When the BET specific surface area value is less than 0.1 m ² / g, the particles are coarse or the particles are sintered between the particles and the coloring power is reduced. More preferably, it is 0.5-10 m < ² > / g, More preferably, it is 0.5-5 m < ² > / g.

When the black pigment of the present invention is used as a near-infrared shielding material, the near-infrared shielding ability is also affected by the particle size of the black pigment, so that the average particle diameter (maximum diameter of one particle) measured from an electron micrograph Is preferably in the range of 0.1 to 5.0 μm because the near-infrared shielding ability is higher, more preferably 0.2 to 2.0 μm, and still more preferably 0.3 to 1.0 μm. It is. Moreover, when it represents with a BET specific surface area value, it will be preferable if it is the range of 0.3-15.0 m < ² > / g, since near-infrared shielding ability becomes higher, More preferably, 0.7-8.0 m < ² > / g, More preferably, it is 1.4-5.0 m < ² > / g.

  The black pigment of the present invention can be used as a colorant for paints, plastics, ceramics, inks, electronic materials, etc., but in order to increase the dispersibility in solvents and resins to be blended, the particle surface can be used as necessary. An inorganic compound or an organic compound may be coated. Examples of inorganic compounds include silicon, zirconium, aluminum, titanium oxides, and hydrated oxides. Examples of organic compounds include organic silicon compounds, organometallic compounds, polyols, alkanolamines, or derivatives thereof. Higher fatty acids or metal salts thereof, higher hydrocarbons or derivatives thereof, and the like, and at least one selected from these can be used.

  The black pigment of the present invention is a mixture of a calcium compound, an iron compound, and a compound containing at least one element selected from Mg, Mn and Zn, fired, and at least one element selected from Mg, Mn and Zn. Is produced by dissolving 0.05 to 5 mol%. As the calcium compound, calcium oxide, calcium carbonate, calcium fluoride and the like can be used, and as the iron compound, iron oxide, iron hydroxide and the like can be used. Examples of the magnesium compound include magnesium oxide, magnesium carbonate, and magnesium fluoride. Examples of the manganese compound include manganese oxide, manganese carbonate, and manganese fluoride. Examples of the zinc compound include zinc oxide, zinc fluoride, and zinc oxalate. And the like can be appropriately selected from these compounds and used. In the present invention, iron oxide as the iron compound, calcium carbonate as the calcium compound, magnesium oxide as the magnesium compound, manganese oxide as the manganese compound, and zinc oxide as the zinc compound are easy to handle and stable. preferable.

  Next, each of the raw material compounds is weighed and mixed. The mixing method may be either dry mixing in a powder state or wet mixing in a slurry state, and may be performed using a conventional mixer such as a stirring mixer. Moreover, it can also mix in the case of a grinding | pulverization, drying, granulation, and shaping | molding using various grinders, spray dryers, granulators, and molding machines.

  Next, the mixture of raw material compounds is granulated and molded as necessary, and then fired. The firing temperature may be at least a temperature at which the raw material compound undergoes a solid-phase reaction to form a solid solution, and may be, for example, a temperature in the range of 1000 to 1300 ° C. The atmosphere during firing can be any atmosphere, but firing in air is preferable in order to maintain sufficient blackness and near infrared shielding ability. The black pigment obtained by the above baking can be used in various forms such as a powder and a molded body, but when used as a powder, it may be appropriately pulverized to adjust the particle size as necessary. When used as a powder, the powder may be formed into an appropriate size and shape. As the pulverizer, for example, an impact pulverizer such as a hammer mill and a pin mill, a grinding pulverizer such as a roller mill and a pulverizer, and an airflow pulverizer such as a jet mill can be used. As the molding machine, for example, a general-purpose molding machine such as an extrusion molding machine or a granulator can be used.

  Next, the present invention is a paint obtained by blending the above-mentioned black pigment, and the paint of the present invention includes a composition called ink or ink. Moreover, this invention is a resin composition formed by containing the said black pigment. Moreover, this invention is the black material and near-infrared shielding material to which the coating material formed by mix | blending the said black pigment is apply | coated.

  When the black pigment of the present invention is blended with a resin such as a plastic molding such as a paint, ink or film, a composition utilizing its excellent coloring performance can be obtained. The paint, ink, and resin composition may contain any amount of black pigment based on the resin, preferably 0.1% by weight or more, more preferably 1% by weight or more, and still more preferably 10% by weight. The above can be mix | blended. In addition, a composition forming material used in each field may be blended, and various additives may be blended.

  Specifically, in the case of paints and inks, in addition to coating film forming materials or ink film forming materials, solvents, dispersants, pigments, fillers, aggregates, thickeners, flow control agents, leveling agents, curing An agent, a crosslinking agent, a curing catalyst, and the like can be blended. Examples of coating film forming materials include organic components such as acrylic resins, alkyd resins, urethane resins, polyester resins, and amino resins, and inorganic components such as organosilicates, organotitanates, cements, and gypsum. be able to. As the ink film forming material, urethane resin, acrylic resin, polyamide resin, vinyl acetate resin, chlorinated propylene resin, and the like can be used. Various materials such as thermosetting resin, room temperature curable resin, and ultraviolet curable resin can be used for these coating film forming material and ink film forming material. When a resin is used, a photopolymerization initiator or photosensitizer is blended, and UV light is applied and cured after application, a coating with excellent hardness and adhesion can be obtained without applying a thermal load to the substrate. Therefore, it is preferable.

  The coating material of the present invention can be applied on a substrate to produce a black material or a near infrared shielding material. This black material can be used as a coloring material, and the near-infrared shielding material can also be used as a heat shielding material by shielding near-infrared rays. As the substrate, various materials and materials can be used. Specifically, various building materials and civil engineering materials can be used, and the manufactured black materials and near-infrared shielding materials constitute roof materials, wall materials or floor materials for houses and factories, or roads and sidewalks. It can be used as a paving material. The thickness of the black material and the near-infrared shielding material can be arbitrarily set according to various uses. For example, when used as a roofing material, the thickness is generally 0.1 to 0.6 mm, preferably 0.1 to 0.3 mm. When used as a paving material, the thickness is generally 0.5 to 5 mm, preferably 1 to 5 mm. In order to apply on the substrate, a method by application, spraying or a method by iron is possible, and after application, it may be dried, baked or cured as necessary.

  In addition, when the resin composition is used, in addition to the resin, the pigment, dye, dispersant, lubricant, antioxidant, ultraviolet absorber, light stabilizer, antistatic agent, flame retardant, disinfectant, etc. It is kneaded with the pigment and formed into an arbitrary shape such as a film. Examples of the resin include polyolefin resins, polystyrene resins, polyester resins, acrylic resins, polycarbonate resins, fluorine resins, polyamide resins, cellulose resins, polylactic acid resins and other thermoplastic resins, phenol resins, Thermosetting resins such as urethane resins can be used. Such a resin composition can be formed into an arbitrary shape such as a film, a sheet, or a plate and used as a black material for industrial use, agricultural use, home use use, or a near infrared shielding material. It can also be used as a heat shield by shielding near infrared rays.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention, this invention is not limited to those Examples.

Example 1
Calcium carbonate CaCO ₃ (manufactured by High Purity Chemical Laboratory, 99.99%) 3.65 g, ferric trioxide Fe ₂ O ₃ (manufactured by High Purity Chemical Laboratory, 99%) 2.56 g and zinc oxide ZnO (high purity After fully mixing and stirring 0.36 g in an agate mortar, a predetermined amount is placed in an alumina crucible and baked in air at 1100 ° C. for 2 hours to obtain the black pigment of the present invention. (Sample A) was obtained.
Sample A had a solid solution of 2.7 mol% of Zn with respect to the number of moles of all components from the results of fluorescent X-ray analysis and the like.
From the result of fluorescent X-ray analysis, the molar ratios of Zn / Ca = 0.120 and Zn / Fe = 0.140 indicate that Ca ₂ (Fe _1.76 Zn ₀ having a brown mirror light structure). _.24) was estimated to be a composition represented by O _5.

Example 2
3.67 g of calcium carbonate CaCO ₃ (manufactured by High Purity Chemical Laboratory, 99.99%), 2.84 g of ferric trioxide Fe ₂ O ₃ (manufactured by High Purity Chemical Laboratory, 99%) and zinc oxide ZnO (high purity) After sufficiently mixing and stirring 0.09 g (made by Chemical Research Laboratory, 99.99%) in an agate mortar, a predetermined amount is placed in an alumina crucible and baked at 1100 ° C. for 2 hours in the air to produce the black pigment of the present invention. (Sample B) was obtained.
Sample B had a solid solution of 0.67 mol% of Zn with respect to the number of moles of all components from the results of X-ray fluorescence analysis and the like.
From the results of fluorescent X-ray analysis, the molar ratios of Zn / Ca = 0.030 and Zn / Fe = 0.031 indicate that Ca ₂ (Fe _1.94 Zn ₀ having a brown mirror light structure). _.06) was estimated to be a composition represented by O _5.

Example 3
Calcium carbonate CaCO ₃ (manufactured by High Purity Chemical Laboratory, 99.99%) 3.68 g, ferric trioxide Fe ₂ O ₃ (manufactured by High Purity Chemical Laboratory, 99%) 2.59 g and manganese dioxide MnO ₂ (high After sufficiently mixing and stirring 0.38 g in an agate mortar, a predetermined amount is placed in an alumina crucible and baked in air at 1100 ° C. for 2 hours to obtain the black color of the present invention. A pigment (sample C) was obtained.
In Sample C, Mn was dissolved in 2.7 mol% with respect to the number of moles of all components from the result of X-ray fluorescence analysis or the like.
In addition, since it was Mn / Ca = 0.120 and Mn / Fe = 0.140 in terms of molar ratio based on the result of fluorescent X-ray analysis, Ca ₂ (Fe _1.76 Mn ₀ having a brown mirror light structure). _.24) was estimated to be a composition represented by O _5.

Example 4
3.68 g of calcium carbonate CaCO ₃ (manufactured by High Purity Chemical Laboratory, 99.99%), 2.85 g of ferric trioxide Fe ₂ O ₃ (manufactured by High Purity Chemical Laboratory, 99%) and manganese dioxide MnO ₂ (high Purified Chemical Research Laboratory, 99.99%) 0.10 g was mixed and stirred thoroughly in an agate mortar, then placed in an alumina crucible and baked in air at 1100 ° C. for 2 hours to obtain the black color of the present invention. A pigment (sample D) was obtained.
Sample D had a solid solution of 0.67 mol% of Mn with respect to the number of moles of all components from the results of X-ray fluorescence analysis and the like.
In addition, since it was Mn / Ca = 0.030 and Mn / Fe = 0.031 in terms of molar ratio based on the result of fluorescent X-ray analysis, Ca ₂ (Fe _1.94 Mn ₀ having a brown mirror light structure). _.06) was estimated to be a composition represented by O _5.

Example 5
3.79 g of calcium carbonate CaCO ₃ (manufactured by High Purity Chemical Laboratory, 99.99%), 2.66 g of ferric trioxide Fe ₂ O ₃ (manufactured by High Purity Chemical Laboratory, 99%) and magnesium oxide MgO (high purity) After sufficiently mixing and stirring 0.18 g (made by Chemical Research Laboratory, 99.99%) in an agate mortar, a predetermined amount is placed in an alumina crucible and baked in air at 1100 ° C. for 2 hours to produce the black pigment of the present invention (Sample E) was obtained.
Sample E had a solid solution of 0.67 mol% of Mg with respect to the number of moles of all components from the results of fluorescent X-ray analysis and the like.
In addition, since it was expressed by molar ratio from the result of the fluorescent X-ray analysis, and Mg / Ca = 0.030 and Mg / Fe = 0.031, Ca ₂ (Fe _1.94 Mg ₀ having a brown mirror light structure). _.06) was estimated to be a composition represented by O _5.

Comparative Example 1
Calcium carbonate CaCO ₃ (manufactured by High Purity Chemical Laboratory, 99.99%) 3.68 g and ferric trioxide Fe ₂ O ₃ (manufactured by High Purity Chemical Laboratory, 99%) 2.94 g are sufficiently mixed in an agate mortar. -After stirring, a predetermined amount was put into an alumina crucible and baked at 1100 ° C in air for 2 hours to obtain a comparative sample (Sample F).
Sample F was a complex oxide (Ca ₂ Fe ₂ O ₅ ) itself having a brown mirror light structure.

Comparative Example 2
2.32 g of calcium carbonate CaCO ₃ (manufactured by High Purity Chemical Research Laboratory, 99.99%) and 3.70 g of ferric trioxide Fe ₂ O ₃ (manufactured by High Purity Chemical Research Laboratory, 99%) are thoroughly mixed in an agate mortar. -After stirring, a predetermined amount was put in an alumina crucible and baked at 1100 ° C in air for 2 hours to obtain a comparative sample (sample G).
Sample G was a complex oxide (CaFe ₂ O ₄ ) itself.

Samples (A to F) obtained in Examples and Comparative Examples were sufficiently pulverized in an agate mortar, and then the sample was placed in a 30 mmφ aluminum ring, subjected to a load of 9.8 MPa, press molded, and a whiteness meter NW- 1 (manufactured by Nippon Denshoku Industries Co., Ltd.) was used to measure the color of the powder, and the results are shown in Table 1. Samples A to E obtained in the examples have an L ^* value of 30 or less, sufficient blackness, an a ^* value of about 0 to 20, and a b ^* value of −1. Since the hue of about 10 to 10 was shown, the present invention was found to be used as a black pigment. On the other hand, the sample F obtained in the comparative example had an L ^* value greater than 30, an a ^* value of 20 or more (strong redness), and a b ^* value that was relatively high. Further, the L ^* value, a ^* value, and b ^* value of Sample G were not measured, but were visually reddish and could not be used as a black pigment.

In addition, the samples (A to F) obtained in Examples and Comparative Examples were put into a dedicated cell, and an ultraviolet-visible near-infrared spectrophotometer V-570 (manufactured by JASCO Corporation, Spectralon <manufactured by Labsphere> as a standard reflector) The spectral reflectance (reflectance of light having a wavelength of 350 to 2100 nm) is measured in accordance with JIS R 3106, and then the reflectance of near infrared rays in the range of 700 to 2100 nm in sunlight. ) Was calculated and shown in Table 1.
The solar reflectances of Samples A to E obtained in the Examples were all lower than the value of Sample F of Comparative Example 1, but about 10% for Sample A, about 14% for Sample B, Sample C, Since it was about 20% for E and over 40% for sample D, it was found that the sample had sufficient near-infrared shielding ability, in particular, samples B to E had good near-infrared shielding ability.

The black pigment of the present invention is a complex oxide containing calcium, iron, oxygen and at least one element selected from Mg, Mn and Zn, and is an inorganic black pigment having sufficient blackness, Since it has excellent characteristics such as excellent stability and heat resistance, and no concern about safety and environmental problems, it can be used in various colorant applications such as paints, inks, and resin compositions.
Further, the black pigment of the present invention retains sufficient near-infrared shielding ability, and is applied to the roof or outer wall of a building, or used as a resin composition such as a film or sheet for mitigating the heat island phenomenon. be able to.
And since it can manufacture in air | atmosphere without using an expensive raw material, it can manufacture comparatively cheaply.

4 is an electron micrograph showing the particle shape of sample A. 4 is an electron micrograph showing the particle shape of Sample C. FIG. 3 is an electron micrograph showing the particle shape of sample E. FIG. 3 is an electron micrograph showing the particle shape of Sample F. FIG.

Claims (10)

A black pigment obtained by dissolving 0.05 to 5 mol% of at least one element selected from Mg, Mn, and Zn in a composite oxide containing Ca and Fe. A near-infrared-shielding black pigment obtained by dissolving 0.05 to 5 mol% of at least one element selected from Mg, Mn, and Zn in a composite oxide containing Ca and Fe. The black pigment according to claim 1, wherein the black pigment is a complex oxide having a brown mirror light structure. The black pigment according to claim 1 or 2, wherein the blackness (L ^* value) is 30 or less. The black pigment according to claim 2, wherein the solar reflectance in a wavelength range of 700 to 2100 nm calculated according to JIS R 3106 is 10% or more. Calcium compound, iron compound, and compound containing at least one element selected from Mg, Mn and Zn are mixed and baked, and composite oxide containing Ca and Fe is selected from Mg, Mn and Zn. A method for producing a black pigment, wherein 0.05 to 5 mol% of at least one element is dissolved. The coating material formed by mix | blending the black pigment of Claim 1 or 2. The black material with which the coating material of Claim 7 is apply | coated on the base material. The near-infrared shielding material with which the coating material of Claim 7 is apply | coated on the base material. A resin composition comprising the black pigment according to claim 1.

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