JP2014214057A - Infrared reflective black pigment, coating material using the infrared reflective black pigment, and resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared reflective black pigment that contains Bi, Mn, Zn, and Al, is free from harmful elements, and has both excellent infrared reflection property and excellent coating material stability.SOLUTION: The infrared reflective black pigment is a black pigment composed of a composite oxide containing Bi, Mn, Zn, and Al and having a blackness (L*) of 30 or less and a near-infrared reflectance of 45% or more. The coating material and the resin composition use the infrared reflective black pigment.

Description

  The present invention is a composite oxide containing Bi, Mn, Zn and Al as main components, and is capable of obtaining a heat-shielding coating material having excellent acid resistance, coating stability and excellent infrared reflectivity. Relates to a functional black pigment.

  Roads, buildings, stockpile tanks, automobiles, ships, etc. used outdoors increase the internal temperature due to solar radiation, so sunlight is reduced by changing the exterior paint of buildings and automobiles from white to light. It is reflected to increase the heat shielding effect to some extent.

  However, in particular, the roofs of outdoor buildings are often dark to black in order to make the dirt inconspicuous, and in the case of buildings and automobiles etc. whose exterior paint has a dark to black color. Compared to buildings and automobiles having a light-to-white appearance paint, it is easier to absorb sunlight, and the indoor temperature tends to rise remarkably. It is not preferable that the temperature of the interior becomes high during transportation and storage of the article.

  Therefore, from the viewpoint of energy saving for preventing global warming, it is strongly desired to suppress an increase in internal temperature of buildings and automobiles having a dark to black appearance.

  Conventionally, heat-shielding black paints are known in order to reduce an increase in internal temperature of buildings and automobiles having a dark-colored to black appearance coating (see, for example, Patent Documents 1 to 3). In addition, strontium iron oxide perovskite having excellent blackness is known (for example, see Patent Document 4). Further, magnesium and aluminum-containing iron oxides having excellent blackness are known (see, for example, Patent Document 5). However, it has the following problems.

Patent Document 1 describes a black calcined pigment having a spinel structure composed of CoO, Cr ₂ O ₃ and Fe ₂ O ₃ , which contains Cr and has an infrared region wavelength of 780 to 2500 nm. The average reflectance was less than 30%, and it was difficult to say that it had a sufficient heat shielding effect.

Patent Document 2 describes a black pigment composed of a calcined pigment containing Fe ₂ O ₃ as an essential component and containing Cr ₂ O ₃ , Mn ₂ O _3, or NiO, but contains Cr. Therefore, it is not preferable.

  Patent Document 3 describes a black complex oxide composed of rare earth elements, alkaline earth metals, and iron, but it is difficult to say that it has a sufficient heat shielding effect.

  Patent Document 4 describes a strontium iron oxide perovskite having excellent blackness, but has an average reflectance of 10% or less at a visible light region wavelength of 250 to 780 nm and an infrared region wavelength of 780. Since the average reflectance at ˜2500 nm is less than 30%, a sufficient heat shielding effect is not obtained.

  Patent Document 5 describes magnesium-aluminum-containing spinels with excellent blackness, but has an average reflectance of 10% or less at a visible light region wavelength of 250 to 780 nm and an infrared region wavelength of 780. Since the average reflectance at ˜2500 nm is less than 30%, a sufficient heat shielding effect is not obtained.

In Patent Document 6, CuO as a black pigment is excellent in blackness and heat shielding properties, but has a problem in acid resistance. On the other hand, experimental data that pigments mainly composed of CuO—Cr ₂ O ₃ have low solar reflectance and near infrared reflectance are also disclosed.

  In order to solve the above problems, the present applicant has developed an infrared reflective black pigment that does not contain harmful elements and has excellent infrared reflectivity, and has already filed a patent application (see Patent Document 7). This black pigment contains Fe, Co, and Al, and further includes a composite oxide containing one or more metal elements selected from Mg, Ca, Sr, Ba, Ti, Zn, Sn, Zr, Si, and Cu. The black pigment is an infrared reflective black pigment having an average particle diameter of 0.02 to 2.0 μm, does not contain harmful elements, and has excellent infrared reflectivity. However, it cannot be said that the reflectance in the infrared region wavelength of 1500 nm is sufficiently high.

  Further, a composite oxide of Bi and Mn is known as a black pigment other than the black pigment (Patent Document 8). BiMn composite oxide is excellent in blackness and heat shielding properties, but has problems in acid resistance and paint stabilization.

JP 2000-72990 A JP 2001-311049 A JP 2004-83616 A JP 2000-264639 A JP 2003-238164 A JP 2002-331611 A JP 2007-197570 A JP-T-2002-532379

  Although several black pigments have been developed as black pigments that do not contain harmful elements and have excellent infrared reflectivity as described above, these pigments are not necessarily sufficient, and further improvements are required. Yes.

  An object of the present invention is to provide an infrared reflective black pigment which is mainly composed of Bi, Mn, Zn and Al, has excellent infrared reflectivity, and is excellent in acid resistance and paint stability.

  The object can be achieved by the present invention as follows.

  That is, the present invention is a black pigment made of a composite oxide containing Bi, Mn, Zn, and Al, and the black pigment has a blackness (L *) of 30 or less and a near infrared reflectance. It is an infrared reflective black pigment characterized by being 45% or more (Invention 1).

Moreover, this invention is an infrared reflective black pigment of this invention 1 whose true specific gravity is 5.0-7.0 g / cm < ³ > or less (this invention 2).

  Further, in the present invention, the surface treatment agent for coating the surface of the infrared reflective black pigment according to the present invention 1 or 2 is one or more compounds selected from Si, Al, Zr, Ti, Zn, and P, or an organic system. It is an infrared reflective black pigment characterized by being a surface treatment agent (Invention 3).

  Moreover, this invention is an infrared reflective black pigment with which the acid resistance of the infrared reflective black pigment in any one of this invention 1-3 was excellent (this invention 4).

  Moreover, this invention is the coating material which mix | blended the infrared reflective black pigment in any one of this invention 1-3 (this invention 5).

  Moreover, this invention is the resin composition colored using the infrared reflective black pigment in any one of this invention 1-3 (this invention 6).

The infrared reflective black pigment according to the present invention is a complex oxide containing Bi, Mn, Zn and Al, and is a safe black pigment containing no harmful elements such as Cr ⁶⁺ and Co. Since it has reflectivity, it is suitable as an infrared reflective black pigment.

  Moreover, since the infrared reflective black pigment which concerns on this invention does not contain elements, such as alkaline-earth metal (Ca, Sr, and Ba), it is excellent in acid resistance and is suitable for an infrared reflective black pigment.

  The configuration of the present invention will be described in more detail as follows.

  First, the infrared reflective black pigment according to the present invention will be described.

  Further, the infrared reflective black pigment according to the present invention is a composite oxide mainly composed of Bi, Mn, Zn and Al, and does not contain an expensive element such as Co. Therefore, as an inexpensive infrared reflective black pigment, Is preferred.

The content ratio of the metal element in the infrared reflective black pigment according to the present invention is such that Bi is 5 to 40 mol%, Mn is 10 to 60 mol%, and Zn is 1 to 30 with respect to all metal elements in the black pigment. Mol% and Al are preferably 5 to 50 mol%. More preferably, Bi is 10 to 35 mol%, Mn is 15 to 55 mol%, Zn is 5 to 25 mol%, and Al is 10 to 45 mol%. Outside the above range, it is difficult to say that the infrared reflectance or blackness (L ^* ) value is sufficient. In addition, the infrared reflective black pigment according to the present invention may inevitably contain impurities derived from various raw materials, but the amount thereof is very small.

  The average particle size of the infrared reflective black pigment according to the present invention is preferably 0.02 to 5.0 μm. When the average particle diameter of the black pigment 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 vehicle may be difficult. More preferably, it is 0.025-4.0 micrometers, More preferably, it is 0.04-2.0 micrometers.

Further, the BET specific surface area of the infrared reflective black pigment according to the present invention is preferably 1 to 100 m ² / g. When the BET specific surface area is less than 1 m ² / g, the particles are coarse or the particles are sintered between the particles and the coloring power is reduced. On the other hand, when the BET specific surface area exceeds 100 m ² / g, aggregation is likely to occur due to an increase in intermolecular force due to particle miniaturization, so that it is difficult to uniformly coat the particle surface with a surface treatment agent. More preferably, it is 1.5-75 m < ² > / g, More preferably, it is 1.8-65 m < ² > / g.

The lightness (L ^* ) of the infrared reflective black pigment according to the present invention is 30 or less. When the lightness (L ^* ) is outside the above range, it is difficult to say that it is a black pigment. The lightness (L ^* ) is preferably 28 or less, more preferably 25 or less.

The a ^* of the infrared reflective black pigment according to the present invention is preferably −2 to +10. When a ^* is outside the above range, it is difficult to say a black pigment. More preferably, it is -1 to +5.

The b ^* of the infrared reflective black pigment according to the present invention is preferably -5 to +10. When b ^* is outside the above range, it is difficult to say a black pigment. More preferably, it is −4 to +5.

  Further, the infrared reflectance of the infrared reflective black pigment according to the present invention is such that the near infrared reflectance is 45% or more when the lacquer color sample coating film is measured according to JIS K5602. If the infrared reflectance is less than 45%, it cannot be said that the near infrared reflectance is sufficiently high. More preferably, the infrared reflectance is 45.5% or more.

The true specific gravity of the infrared reflective black pigment according to the present invention is preferably 5.0 to 7.0 g / cm ³ . By controlling the true specific gravity within the above range, the stability of the paint is improved. The more preferable true specific gravity is 5.4 to 6.8 g / cm ³ , and still more preferably 5.6 to 6.6 g / cm ³ .

  Moreover, as for the acid resistance of the infrared reflective black pigment which concerns on this invention, the solubility of Bi measured by the evaluation method mentioned later has 1000 ppm or less. When the acid resistance value exceeds 1000 ppm, the color difference ΔE after the acid resistance evaluation becomes large. More preferable acid resistance is 600 ppm or less.

  In addition, the shape of the particles of the infrared reflective black pigment according to the present invention is not limited to a specific shape, and is spherical, granular, octahedral, hexahedral, polyhedral and other granular particles, needles, spindles, and rice grains Such needle-like particles and plate-like particles can be used. Considering the dispersibility of the resulting black pigment, spherical particles and granular particles are preferred.

  The infrared reflective black pigment according to the present invention covers the surface of an infrared reflective black pigment using one or more compounds selected from Si, Al, Zr, Ti, Zn, and P or an organic surface treatment agent. Can do.

  As one or more kinds of compounds selected from Si, Al, Zr, Ti, Zn, and P, as aluminum compounds, aluminum salts such as aluminum acetate, aluminum sulfate, aluminum chloride, and aluminum nitrate; and aluminates such as sodium aluminate Examples include alkali salts. Examples of the silicon compound include No. 3 water glass, sodium orthosilicate, sodium metasilicate, and the like. As the zirconium compound, zirconium salts such as zirconium acetate, zirconium sulfate, zirconium chloride, and zirconium nitrate can be used. As the titanium compound, titanium salts such as titanium acetate, titanium sulfate, titanium chloride, and titanium nitrate can be used. As the zinc compound, zinc salts such as zinc acetate, zinc sulfate, zinc chloride, and zinc nitrate can be used. As the phosphorus compound, phosphates such as sodium hydrogen phosphate, sodium ammonium hydrogen phosphate, potassium phosphate, sodium polyphosphate, sodium hexametaphosphate and the like can be used.

  Organic surface treatment agents include stearic acid or salts thereof, rosin, alkoxysilanes, fluoroalkylsilanes, silane coupling agents, organosilicon compounds such as organopolysiloxanes, titanates, aluminates, and zirconates. Examples thereof include a ring agent, a low molecular or high molecular surfactant, and a phosphoric acid compound.

  Specific examples of the organosilicon compound include methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, and ethyl. Alkoxysilanes such as triethoxysilane, propyltriethoxysilane, butyltriethoxysilane, isobutyltrimethoxysilane, hexyltriethoxysilane, octyltriethoxysilane and decyltriethoxysilane, trifluoropropyltrimethoxysilane, tridecafluorooctyltri Methoxysilane, heptadecafluorodecyltrimethoxysilane, trifluoropropyltriethoxysilane, heptadecafluorodecyltrie Fluoroalkylsilanes such as xylsilane and tridecafluorooctyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane Silane cups such as γ-methacryloyloxypropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane Examples include ring agents, organopolysiloxanes such as polysiloxane, methylhydrogen polysiloxane, and modified polysiloxane.

  Examples of titanate coupling agents include isopropyl tristearoyl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, isopropyl tri (N-aminoethylaminoethyl) titanate, tetraoctyl bis (ditridecyl phosphate) titanate, tetra (2- Examples include 2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphate titanate, bis (dioctylpyrophosphate) oxyacetate titanate, and bis (dioctylpyrophosphate) ethylene titanate.

  Examples of the aluminate coupling agent include acetoalkoxy aluminum diisopropylate, aluminum diisopropoxy monoethyl acetoacetate, aluminum trisethyl acetoacetate, aluminum trisacetylacetonate and the like.

  Examples of the zirconate coupling agent include zirconium tetrakisacetylacetonate, zirconium dibutoxybisacetylacetonate, zirconium tetrakisethylacetoacetate, zirconium tributoxymonoethylacetoacetate, zirconium tributoxyacetylacetonate and the like.

  Examples of the low molecular surfactant include alkylbenzene sulfonate, dioctyl sulfone succinate, alkylamine acetate, alkyl fatty acid salt and the like. Examples of the polymeric surfactant include polyvinyl alcohol, polyacrylate, carboxymethylcellulose, acrylic acid-maleate copolymer, and olefin-maleate copolymer.

  Examples of phosphoric acid compounds include organic phosphorus compounds such as phosphoric acid esters, phosphorous acid esters, acidic phosphoric acid esters, and phosphonic acids.

  Next, the manufacturing method of the infrared reflective black pigment which concerns on this invention is described.

  The infrared reflective black pigment comprising the composite oxide according to the present invention can be obtained by mixing and firing various raw materials.

  The mixing of the starting materials is not particularly limited as long as the starting materials can be uniformly mixed, and may be wet mixing or dry mixing. Also, wet synthesis may be used.

  The heating and baking temperature is preferably 600 to 950 ° C, and more preferably 650 to 850 ° C. The heating atmosphere is air.

  The heated powder may be washed and pulverized according to a conventional method.

  In the present invention, the particle surface of the infrared reflective black pigment may be coated with one or more compounds selected from Si, Al, Zr, Ti, Zn, and P. The surface treatment method may be performed according to a conventional method such as a wet method or a dry method. For example, in the wet method, one or two or more soluble compounds selected from Si, Al, and Zr are added to and mixed with a slurry of a wet-dispersed infrared reflective black pigment while adjusting the pH with an acid or an alkali. The dry method is a method in which an infrared reflective black pigment is coated with one or more coupling agents selected from Si, Al and Zr in an apparatus such as a Henschel mixer.

  In the dry method, the device used for mixing and stirring is preferably a device capable of applying a shearing force to the powder layer, and a device capable of simultaneously performing shearing, spatula and compression, for example, a wheel type kneader, a ball type kneading device. It is preferable to use a machine, a blade-type kneader, or a roll-type kneader. A wheel-type kneader can be used more effectively.

  Examples of the wheel-type kneader include an edge runner (synonymous with “mix muller”, “simpson mill”, “sand mill”), multi-mal, stotz mill, wet pan mill, conner mill, ring muller, etc., preferably edge Runners, multi-mals, stocks mills, wet pan mills and ring mullers, more preferably edge runners. As the ball kneader, there is a vibration mill. Examples of the blade type kneader include a Henschel mixer, a planetary mixer, and a nauta mixer. As the roll type kneader, there is an extruder.

  As an apparatus used for mixing and stirring the black pigment and the surface treatment agent, an apparatus capable of applying a shearing force to the powder layer is preferable. It is preferable to use a ball-type kneader, a blade-type kneader, or a roll-type kneader. A wheel-type kneader can be used more effectively.

  Examples of the wheel-type kneader include an edge runner (synonymous with “mix muller”, “simpson mill”, “sand mill”), multi-mal, stotz mill, wet pan mill, conner mill, ring muller, etc., preferably edge Runners, multi-mals, stocks mills, wet pan mills and ring mullers, more preferably edge runners. As the ball kneader, there is a vibration mill. Examples of the blade type kneader include a Henschel mixer, a planetary mixer, and a nauta mixer. As the roll type kneader, there is an extruder.

  Next, a paint containing the infrared reflective black pigment according to the present invention will be described.

  The blending ratio of the infrared reflective black pigment in the paint according to the present invention can be used in the range of 0.5 to 100 parts by weight with respect to 100 parts by weight of the paint base material, and the handleability of the paint is taken into consideration. For example, it is preferably 1.0 to 100 parts by weight.

  As the paint constituent base material, a resin, a solvent, and if necessary, fats and oils, an antifoaming agent, an extender pigment, a drying accelerator, a surfactant, a curing accelerator, an auxiliary agent and the like are blended.

  Resins include acrylic resin, alkyd resin, polyester resin, polyurethane resin, epoxy resin, phenol resin, melamine resin, amino resin, vinyl chloride resin, silicone resin, gum rosin that are usually used for solvent-based paints and oil-based printing inks. Rosin resin such as lime rosin, maleic acid resin, polyamide resin, nitrocellulose, ethylene-vinyl acetate copolymer resin, rosin modified phenolic resin, rosin modified maleic resin and other rosin modified resins, petroleum resin, fluororesin, etc. be able to. For water-based paints, water-soluble acrylic resins, water-soluble styrene-maleic acid resins, water-soluble alkyd resins, water-soluble melamine resins, water-soluble urethane emulsion resins, water-soluble epoxies commonly used for water-based paints and water-based inks Resins, water-soluble polyester resins, water-soluble fluororesins, and the like can be used.

  Solvents include soybean oil, toluene, xylene, thinner, butyl acetate, methyl acetate, methyl isobutyl ketone, methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, etc. Glycol ether solvents, ester solvents such as ethyl acetate, butyl acetate, and amyl acetate, aliphatic hydrocarbon solvents such as hexane, heptane, and octane, alicyclic hydrocarbon solvents such as cyclohexane, and petroleum-based solvents such as mineral spirits Solvents, ketone solvents such as acetone and methyl ethyl ketone, alcohol solvents such as methyl alcohol, ethyl alcohol, propyl alcohol, and butyl alcohol, aliphatic hydrocarbons, and the like can be used.

  Water-based paint solvents include water and alcohol-based solvents usually used for water-based paints, such as ethyl alcohol, propyl alcohol, and butyl alcohol, methyl ether solvents such as methyl cellosolve, ethyl cellosolve, propyl cellosolve, and butyl cellosolve, and diethylene glycol. , Oxyethylene or oxypropylene addition polymers such as triethylene glycol, polyethylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, alkylene glycol such as ethylene glycol, propylene glycol, 1,2,6-hexanetriol, glycerin, It can be used by mixing with a water-soluble organic solvent such as 2-pyrrolidone.

  As oils and fats, boil oils obtained by processing dry oils such as linseed oil, persimmon oil, sea lion oil, safflower oil and the like can be used.

  Antifoaming agents include Nopco 8034 (product name), SN deformer 477 (product name), SN deformer 5013 (product name), SN deformer 247 (product name), SN deformer 382 (product name) (all of these are San Nopco Commercially available products such as manufactured by Co., Ltd., Antihome 08 (trade name), Emulgen 903 (trade name) (all of which are manufactured by Kao Corporation) can be used.

  Next, the resin composition containing the infrared reflective black pigment according to the present invention will be described.

  The blending ratio of the infrared reflective black pigment in the resin composition according to the present invention can be used in the range of 0.01 to 200 parts by weight with respect to 100 parts by weight of the resin, and the handling property of the resin composition is taken into consideration. Thus, the amount is preferably 0.05 to 150 parts by weight, more preferably 0.1 to 100 parts by weight.

  As a constituent substrate in the resin composition according to the present invention, an additive such as a lubricant, a plasticizer, an antioxidant, an ultraviolet absorber, and various stabilizers, if necessary, together with an infrared reflective black pigment and a known thermoplastic resin. Is blended.

  Examples of the resin include polyolefins such as polyethylene, polypropylene, polybutene, and polyisobutylene, polyvinyl chloride, polymethylpentene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, styrene-acrylic acid ester copolymer, styrene-vinyl acetate copolymer, Acrylonitrile-butadiene-styrene copolymer, acrylonitrile-EPDM-styrene copolymer, acrylic resin, polyamide, polycarbonate, polyacetal, polyurethane and other thermoplastic resins, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, Silicone resin, rosin ester, rosin, natural rubber, synthetic rubber and the like can be used.

  The amount of the additive may be 50% by weight or less based on the sum of the infrared reflective black pigment and the resin. When the content of the additive exceeds 50% by weight, the moldability is lowered.

  The resin composition according to the present invention is prepared by mixing a resin raw material and an infrared reflective black pigment in advance, and then applying a strong shearing action under heating using a kneader or an extruder to produce an infrared reflective black pigment. The aggregate is broken and the infrared reflective black pigment is uniformly dispersed in the resin composition, and then molded into a shape suitable for the purpose.

  The resin composition according to the present invention can also be obtained via a master batch pellet.

  The master batch pellet in the present invention requires a binder resin as a constituent substrate of the paint and the resin composition and the infrared reflective black pigment, and a mixer such as a ribbon blender, a Nauter mixer, a Henschel mixer, a super mixer, etc. Kneaded with a well-known single-screw kneading extruder or twin-screw kneading extruder, etc., then cut, or kneaded by mixing the above mixture with a Banbury mixer, pressure kneader, etc. It is manufactured by crushing, molding or cutting.

  As for the supply of the binder resin and the infrared reflective black pigment to the kneader, each of them may be supplied at a predetermined ratio, or a mixture of both may be supplied.

  The master batch pellet in the present invention has an average major axis of 1 to 6 mm, preferably 2 to 5 mm. The average minor axis is 2 to 5 mm, preferably 2.5 to 4 mm. When the average major axis is less than 1 mm, the workability at the time of producing the pellet is poor, which is not preferable. When the thickness exceeds 6 mm, the difference from the size of the binder resin for dilution is large, and it becomes difficult to sufficiently disperse. Moreover, the shape can be various, and can be indefinite and spherical, cylindrical, flakes, and the like.

  As the binder resin used for the master batch pellet in the present invention, the same resin as the resin for resin composition can be used.

  The composition of the binder resin in the masterbatch pellet may be the same resin as the diluent binder resin or a different resin, but if different resins are used, What is necessary is just to determine in consideration of the various characteristics determined by the compatibility.

  The amount of the infrared reflective black pigment blended in the master batch pellet is 1 to 200 parts by weight, preferably 1 to 150 parts by weight, more preferably 1 to 100 parts by weight with respect to 100 parts by weight of the binder resin. . When the amount is less than 1 part by weight, the melt viscosity at the time of kneading is insufficient, and it is difficult to disperse and mix the infrared reflective black pigment. When the amount exceeds 200 parts by weight, since there is little binder resin for the infrared reflective black pigment, good dispersion and mixing of the infrared reflective black pigment is difficult, and the resin composition can be changed by a slight change in the addition amount of the master batch pellet. Since the content of the infrared-reflective black pigment blended in the product greatly changes, it is difficult to prepare the desired content, which is not preferable. Also, mechanical wear is severe and not suitable.

  A typical embodiment of the present invention is as follows.

  The average particle diameter of the particles was measured by an air permeation method (Fischer method).

  The specific surface area was shown by the value measured by BET method.

  The content of the metal element in the infrared reflective black pigment was measured using a “fluorescence X-ray analyzer 3063M type” (manufactured by Rigaku Denki Kogyo Co., Ltd.) in accordance with “General X-ray fluorescence analysis rules” of JIS K0119.

The hue (L ^* value, a ^* value, b ^* value) of the infrared reflective black pigment was prepared by mixing 0.5 g of a sample and 0.5 ml of castor oil with a Hoover type Mahler to form a paste. .5 g was added, kneaded and converted into a paint, and an application piece (coating thickness: about 30 μm) applied on cast-coated paper using a 150 μm (6 mil) applicator was produced. The coating piece was measured using a “color difference meter CR-300” (manufactured by Konica Minolta Sensing Co., Ltd.), and the color index (L ^* value, a ^* value, b ^* value) according to JIS Z 8729. ).

  The reflectivity of the wavelength in the visible light region and the infrared region of the black pigment for infrared reflection is determined by “spectrophotometer U-4100” (Hitachi High-Technologies Corporation) for the coating film piece prepared for measuring the above hue. The reflectance (%) at a wavelength of 250 to 2500 nm was measured. Near-infrared reflectance was measured according to JIS K 5602.

  The acid resistance of the infrared reflective black pigment was evaluated according to JIS K5101-8 “Pigment test method Part 8: Chemical resistance”. Add 2 g of pigment and 20 ml of 5% sulfuric acid to the test tube and seal it well. Let stand for 15 minutes. After standing, seal again and shake and leave for 30 minutes. After allowing to stand, the amount of Bi of the solution after filtration and separation was measured by ICP, and dissolved Bi was analyzed.

  For the color difference ΔE, the pigment after acid resistance evaluation is washed with water until the pH of the filtrate becomes neutral, and then dried in a dryer at 80 ° C. for 3 hours. Thereafter, the above-described hue evaluation was performed, and the color difference ΔE was obtained by comparison with the untreated pigment.

The paint containing the infrared reflective black pigment was evaluated in the following manner.
In mayonnaise bottle (internal volume 140 ml), 90 g of glass beads, 10 g of black pigment, 16.0 g of amino alkyd resin (clear), 6.0 g of solvent were blended, dispersed for 40 minutes with a paint conditioner, and further aluminum alkyd resin ( After adding 50 g of (clear), it was dispersed with a paint conditioner for 5 minutes and separated from glass beads. Thereafter, the mixture was allowed to stand for 24 hours to precipitate the black pigment. Evaluation was made based on the ease and difficulty of redispersibility when the precipitate was stirred with a stirrer.

Example 1
The raw material oxides were weighed and mixed so as to have the contents shown in Table 1 below, and baked at 800 ° C. for 2 hours using an electric furnace. The fired product was pulverized to obtain an infrared reflective black pigment. As a result of X-ray diffraction, the obtained infrared reflective black pigment is a composite oxide of Mn—Bi—Al—Zn, a black pigment having a BET specific surface area of 2.1 m ² / g and an average particle diameter of 1.7 μm. there were.

  This pigment was coated with a lacquer color to prepare a color sample sample, and the reflectance was evaluated in a wavelength range of 250 nm to 2500 nm using a U-4100 Hitachi spectrophotometer. As a result, the near infrared reflectance at a wavelength of 780 to 2500 nm was 45.9%.

Example 2
After synthesizing by a wet method, a black pigment was obtained in the same manner as in Example 1 except that it was calcined at 700 ° C. for 2 hours.

Example 3
A black pigment was obtained in the same manner as in Example 1 except that the raw material composition and the firing temperature were changed.

Example 4
A black pigment was obtained in the same manner as in Example 1. Next, the obtained black pigment was wet-dispersed in water, adjusted to pH 7 with hydrochloric acid and sodium hydroxide while dropping 0.5 wt% of water glass to a black pigment slurry kept at 70 ° C., and maintained for 1 hour. Thereafter, it was washed with water, dehydrated, dried and pulverized.

Examples 5 and 6
A black pigment was obtained in the same manner as in Example 1 except that the calcination temperature during the production of the black pigment was changed and various pulverized powders were dry mixed with various surface treatment agents.

Comparative Examples 1-4
A black pigment was obtained in the same manner as in Example 1 except that the raw material composition and the firing temperature were changed. In Comparative Example 1, BiMn 6301 manufactured by Asahi Chemical Co., Ltd. was used.

The production conditions of the infrared reflective black pigment are shown in Table 1, the characteristics of the obtained infrared reflective black pigment are shown in Table 2, and the characteristics of the paint and the coating film are shown in Table 3. Comparative Example 3 is a mixture of Mn—Bi composite oxide and Al (OH) ₃ prepared in advance, and Comparative Example 4 is a mixture of Mn—Bi composite oxide, Al (OH) ₃ and ZnO.

The infrared reflective black pigment according to the present invention is suitable as a safe infrared reflective black pigment because it is excellent in infrared reflectivity and does not contain harmful elements such as Cr ⁶⁺ and Co. Moreover, since the resin composition containing the infrared-reflective black pigment according to the present invention is excellent in infrared reflectivity, the resin composition is used as a sheet or a film by a known method and used for the following applications. Can do.

  Since the sheet obtained from the resin composition containing the infrared-reflective black pigment according to the present invention is black, if it is used for an agricultural multi-sheet, it is possible to prevent the generation and growth of weeds. Since it is excellent in reflectivity, it is possible to suppress an increase in the temperature of the ground, and it can be suitably used as a black agricultural multi-sheet.

  Similarly, it can be suitably used for a solar cell backsheet. In the solar cell module, the front and back surfaces of a plurality of solar cell elements are protected by a cover material. The back sheet that protects the back surface of the solar cell element is preferably a back sheet having high reflectivity in terms of power conversion efficiency and black in terms of design. Furthermore, the power generation efficiency decreases as the temperature of the solar cell element increases. The sheet | seat obtained from the resin composition containing the infrared reflective black pigment which concerns on this invention is fully equipped with the characteristic required as a solar cell backsheet, and is preferable as a solar cell backsheet.

  In order to make it difficult to see the inside from the outside, a colored film is attached to a window glass of a vehicle and used. However, these films are also required not to raise the indoor temperature. Since the film obtained from the resin composition containing the infrared reflective black pigment according to the present invention is excellent in blackness and infrared reflectiveness, it is preferably used as a colored film to be attached to a window glass of a vehicle or a building. Can do.

Claims (6)

  A black pigment composed of a composite oxide containing Bi, Mn, Zn and Al, wherein the black pigment has a blackness (L *) of 30 or less and a near infrared reflectance of 45% or more. Infrared reflective black pigment characterized by The infrared reflective black pigment according to claim 1, which has a true specific gravity of 5.0 to 7.0 g / cm ³ or less. The surface treatment agent for coating the surface of the infrared reflective black pigment according to claim 1 or 2 is one or more compounds selected from Si, Al, Zr, Ti, Zn, and P, or an organic surface treatment agent. Infrared reflective black pigment characterized by The infrared reflective black pigment which was excellent in acid resistance of the infrared reflective black pigment in any one of Claims 1-3. The coating material which mix | blended the infrared reflective black pigment in any one of Claims 1-3. The resin composition colored using the infrared reflective black pigment in any one of Claims 1-3.