JP5906098B2 - Near-infrared reflector and composition containing the same - Google Patents

Description

  The present invention relates to a chromatic rutile titanium dioxide pigment having solar reflectance in the near infrared region and a method for producing the same. Moreover, this invention relates to the coating composition and resin composition which have the solar reflectivity of the near-infrared area | region containing the said chromatic rutile type titanium dioxide pigment.

  In recent years, as an effective preventive measure for the heat island phenomenon that has become a problem mainly in urban areas, a material having solar reflectance in the near-infrared region with a wavelength range of 780 to 2500 nm is painted on concrete buildings and roads, It reflects sunlight, which is the main cause of heat storage, to prevent heat from entering the building and to suppress the temperature rise on the road surface.

Various materials are known as such solar reflective materials. For example, Cr ₂ O ₃ , Cu—Cr composite oxide, Fe—Cr composite oxide, Co—Fe—Cr composite oxide are used as black materials. And compounds containing chromium such as Cu—Cr—Mn composite oxide are known (see Patent Document 1). In addition, titanium dioxide is known as a white material (see Patent Document 2). As green materials, compounds such as rare earth elements-alkaline earth metal elements-Cu composite oxides are known (see Patent Document 3).

JP 2000-72990 A WO2004 / 052786 JP-A-6-279023

  When used for walls and roofs of buildings, etc., chromatic colors such as green are preferred over the black and white materials described in Patent Documents 1 and 2, but in Patent Document 3 described above, Sufficient near-infrared reflectivity is not obtained.

  Accordingly, the present inventors have developed a near-infrared reflective material having a chromatic color. As a result, a rutile titanium dioxide pigment containing at least 1 to 50 mol% of cobalt element has a green chromatic color. And it discovered that it was the material which has the outstanding performance whose solar reflectance of near infrared region (wavelength 780-2500 nm) is 50% or more.

The present invention is a rutile-type titanium dioxide pigment having a green chromatic color, and has a sufficiently high near-infrared reflectance, and therefore can be used in various places as a near-infrared reflecting material. In addition, it is an excellent near-infrared reflecting material that has high hiding power, good acid resistance, and does not contain harmful substances such as chromium and rare earth elements.
Moreover, this invention is a manufacturing method of a chromatic rutile type titanium dioxide pigment, and can manufacture the said near-infrared reflector by a simple method.
Moreover, the coating composition and the resin composition containing the chromatic rutile titanium dioxide pigment of the present invention can easily impart near infrared reflectivity.

It is a figure which shows the spectral reflectance of wavelength 300-2500nm of sample A (thick line) and G (thin line). It is a figure which shows the spectral reflectance of wavelength 300-2500nm of sample B (thick line) and G (thin line). It is a figure which shows the spectral reflectance of wavelength 300-2500nm of sample C (thick line) and G (thin line). It is a figure which shows the spectral reflectance of wavelength 300-2500nm of sample D (thick line) and G (thin line). It is a figure which shows the spectral reflectance of wavelength 300-2500nm of the sample E (thick line) and G (thin line). It is a figure which shows the spectral reflectance of wavelength 300-2500nm of sample F (thick line) and G (thin line).

  The present invention is a chromatic rutile titanium dioxide pigment containing at least 1 to 50 mol% of cobalt element and having a solar reflectance in the near infrared region of 50% or more.

  When the cobalt element is contained in an amount of 1 to 50 mol% with respect to the rutile type titanium dioxide, the white color tone of the titanium dioxide changes to a chromatic color of green (green to blue). When the cobalt content is less than 1 mol%, the change in color tone is small, which is not preferable. 5-40 mol% is preferable and, as for content of a cobalt element, 10-30 mol% is more preferable.

  The cobalt element is preferably contained by being dissolved (doped) inside the crystal of titanium dioxide or substituted with the titanium element. In order to change to an arbitrary color tone, other elements may be included in addition to the cobalt element. For example, elements such as aluminum, nickel, manganese, and iron may be included. The color tone of the powder is visually observed.

  The chromatic rutile type titanium dioxide pigment has a solar reflectance of 50% or more, preferably 60 to 80%, in the near infrared region having a wavelength of 780 to 2500 nm. Further, the solar reflectance in the visible light region having a wavelength of 300 to 780 nm is preferably 70% or less, and more preferably 30 to 60%. Moreover, 30% or more is preferable and the solar reflectance of all the wavelengths of wavelength 300-2500nm is more preferable, 40-70%.

  The solar reflectance of the chromatic titanium dioxide pigment is obtained by placing the powder in a dedicated cell and using an ultraviolet-visible near-infrared spectrophotometer V-670 (manufactured by JASCO Corporation, Spectralon (manufactured by Labsphere) as a standard reflector) The spectral reflectance (reflectance of light having a wavelength of 300 to 2500 nm) is measured by the method according to JIS R3106.

  The average particle size of the chromatic rutile titanium dioxide pigment is preferably 0.3 to 2.0 μm. If the average particle diameter is smaller than 0.3 μm, the solar reflectance in the near infrared region is low, which is not preferable. If it is larger than 2.0 μm, the hiding power is decreased, which is not preferable. The average particle size is more preferably from 0.3 to 1.5 μm, still more preferably from 0.4 to 1.0 μm.

The average particle diameter is calculated by the following formula assuming that the pigment particles are true spherical from the measured specific surface area (S [m ² / g]) and the density of rutile titanium dioxide (ρ = 4.27 [g / cm ³ ]). The average particle diameter is calculated from 1. The specific surface area is measured by the BET nitrogen adsorption method (one-point method by nitrogen adsorption), and specifically, Macsorb HM model-1201 (manufactured by Mountec Co., Ltd.) can be used.
Formula 1 L [μm] = 6 / (S · ρ)

  The surface of the chromatic rutile titanium dioxide pigment may be coated with an inorganic compound or an organic compound.

  Examples of the inorganic compound include at least one compound selected from silicon, zirconium, aluminum, titanium, antimony, phosphorus and tin, and silicon, zirconium, aluminum, titanium, antimony and tin are oxides and hydrated oxides. Alternatively, a hydroxide compound is more preferable, and phosphorus is more preferably a phosphoric acid or phosphate compound.

The coating amount of the inorganic compound can be appropriately set. For example, it is preferably 0.1 to 50% by weight and more preferably 1.0 to 20% by weight with respect to the titanium dioxide pigment.
The amount of the inorganic compound can be measured by a usual method such as fluorescent X-ray analysis or ICP emission analysis.

  Examples of the organic compound include organosilicon compounds, organometallic compounds, polyols, alkanolamines or derivatives thereof, higher fatty acids or metal salts thereof, higher hydrocarbons or derivatives thereof, and the like. Can be used.

  The chromatic rutile titanium dioxide pigment has sufficient solar reflectance in the near-infrared region. However, when other compounds having infrared reflectivity or compounds having infrared shielding (absorption) ability are mixed, infrared radiation is further increased. The reflectivity can be increased, or the reflectivity at a specific wavelength can be complemented.

  As the compound having infrared reflectivity or the compound having infrared shielding (absorption) ability, those conventionally used can be used. Specifically, titanium dioxide, antimony-doped tin oxide, tungsten oxide, lanthanum boride Inorganic compounds such as metal silver powder, metal copper powder and the like, and titanium dioxide and metal powder are more preferable. The kind and mixing ratio of the compound having infrared reflectivity or the compound having infrared shielding (absorption) ability can be appropriately selected according to the application.

  The chromatic rutile titanium dioxide pigment has a color tone of green or blue, and when mixed with other pigments, it has colors such as red, yellow, green, blue, and intermediate colors thereof. be able to.

  As the pigment, inorganic pigments, organic pigments, lake pigments and the like can be used. Specifically, as inorganic pigments, white pigments such as titanium dioxide, zinc white, precipitated barium sulfate, iron oxide, etc. Examples thereof include red pigments, blue pigments such as ultramarine blue and prussian blue (potassium ferrocyanide), black pigments such as carbon black, and pigments such as aluminum powder. Examples of organic pigments include organic compounds such as anthraquinone, perylene, phthalocyanine, azo series, and azomethiazo series. The type and mixing ratio of the pigment can be appropriately selected according to the color / hue.

  Next, this invention is a manufacturing method of a chromatic rutile type titanium dioxide pigment, Comprising: At least 1-50 mol% compound of cobalt element and hydrous titanium oxide are mixed, Then, it bakes.

  As the cobalt element compound, cobalt sulfate, cobalt chloride, cobalt nitrate, or the like can be used. Hydrous titanium oxide is obtained by hydrolyzing or neutralizing titanium compounds such as titanium sulfate, titanyl sulfate, titanium chloride, titanium oxychloride, titanium nitrate, etc., and is said to be metatitanic acid or orthotitanic acid. Including.

  A cobalt compound and hydrous titanium oxide are mixed and then fired. The firing temperature is preferably 700 to 1200 ° C, more preferably 800 to 1100 ° C. When the firing temperature is lower than 700 ° C., the solar reflectance in the near infrared region is lowered, which is not preferable.

  In order to contain an element other than cobalt element, such as aluminum, nickel, manganese, iron, etc., it may be mixed with hydrous titanium oxide or cobalt compound at the stage before firing, for example, aluminum sulfate, aluminum chloride. Aluminum nitrate or the like can be used.

  In order to coat the surface of the chromatic titanium dioxide pigment with an inorganic compound or organic compound, the usual surface coating method of the titanium dioxide pigment can be used, and the inorganic compound or organic compound is added to the titanium dioxide pigment slurry for coating. Can be.

  The chromatic rutile-type titanium dioxide pigment thus obtained can be used in various forms such as a powder and a molded body, but when used as a powder, it is pulverized as necessary to adjust the particle size. Alternatively, when used as a molded body, the powder may be molded 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.

  Furthermore, the present invention is a solar reflective coating composition in the near-infrared region containing a chromatic rutile type titanium dioxide pigment, which is applied to various substrates such as buildings and roads to produce chromatic rutile type titanium dioxide. It is possible to impart solar reflectance in the near infrared region of the pigment.

  The coating composition is a mixture of a chromatic rutile titanium dioxide pigment, a binder, a solvent, and the like, and includes what is called ink. The content of the chromatic rutile titanium dioxide pigment can be set as appropriate, and is preferably 1% by weight or more, for example. As the binder, those usually used such as a thermosetting resin, a room temperature curable resin, and an ultraviolet curable resin can be appropriately selected. For example, an acrylic resin, an alkyd resin, a urethane resin, a polyester resin, Organic components such as amino resins and inorganic components such as organosilicates, organotitanates, cements, and gypsum can be used. As the solvent, water, organic compounds such as alcohol, and mixtures thereof can be used as appropriate. In addition, a dispersant, a pigment, a filler, an aggregate, a thickener, a flow control agent, a leveling agent, a curing agent, a crosslinking agent, a curing catalyst, and the like can be blended.

  A near-infrared reflective material can be manufactured by applying the coating composition on a substrate. This near-infrared reflecting material can be used as a near-infrared shielding material, and also as a heat shielding material by shielding infrared rays. As the substrate, various materials and materials can be used. Specifically, various building materials, civil engineering materials, etc. can be used, and the manufactured near-infrared reflecting material is a roof material, a wall material or a floor material of a house or a factory, or a pavement material constituting a road or a sidewalk. Can be used as such.

  The thickness of the near-infrared reflecting material can be arbitrarily set according to various applications. 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 material, the thickness is approximately 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.

  Further, the present invention is a near-infrared solar reflective resin composition containing a chromatic rutile type titanium dioxide pigment, kneaded into a resin, film-like, sheet-like, plate-like, three-dimensional, spherical, etc. The solar reflectiveness of the near infrared region which a chromatic rutile type titanium dioxide pigment has can be provided. The resin can be appropriately selected. For example, heat such as polyolefin resin, polystyrene resin, polyester resin, acrylic resin, polycarbonate resin, fluorine resin, polyamide resin, cellulose resin, polylactic acid resin, etc. Thermosetting resins such as plastic resins, phenolic resins, and urethane resins can be used.

  The resin composition may contain pigments, dyes, dispersants, lubricants, antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, flame retardants, bactericides, and the like. Such a resin composition can be formed into an arbitrary shape such as a film, a sheet, or a plate and used as a near-infrared reflecting material for industrial use, agricultural use, household use, and the like. It can also be used as a heat shield by shielding infrared rays.

  Examples of the present invention are shown below, but the present invention is not limited thereto.

(Examples 1-3)
Under stirring, after adding 10 mol% of cobalt sulfate aqueous solution to the aqueous suspension of hydrous titanium oxide (metatitanic acid) with respect to titanium, the pH is adjusted to 8.5 by adding aqueous sodium hydroxide solution and aged for 30 minutes. did. Then, after filtering, washing | cleaning, and drying, it baked at each temperature of 800 degreeC, 900 degreeC, and 1000 degreeC for 8 hours, and obtained the rutile type titanium dioxide pigment (sample A, B, C) of this invention.

(Examples 4 to 6)
In Examples 1 to 3, the rutile titanium dioxide pigment of the present invention (Sample D) was used in the same manner as in Examples 1 to 3 except that the addition amount of the cobalt sulfate aqueous solution was changed to 20 mol% with respect to 10 mol%. , E, F).

(Comparative Example 1)
A near-infrared reflective titanium dioxide pigment (PFR404 manufactured by Ishihara Sangyo Co., Ltd.) was used as a comparative sample G.

(Powder evaluation)
As a result of visual observation, all of the samples A, B, C, D, E, and F were green. Comparative sample G was white. In addition, Tables 1 and 2 show specific surface area values obtained by the nitrogen adsorption method and average particle diameters obtained from the above formula 1. The average particle diameter is in the range of 0.3 to 1.0 μm, and it was found that the average particle diameter is optimal as a near-infrared reflective pigment.

(Measurement and evaluation of solar reflectance)
Samples (A to F) are put into a dedicated cell, and using a UV-Vis near-infrared spectrophotometer V-670 (manufactured by JASCO Corporation, Spectralon (manufactured by Labsphere) as a standard reflector), spectral reflectance ( (Wavelength 300-2500 nm) was measured. The obtained results are shown in Tables 1 and 2 and FIGS. In any sample, the solar reflectance in the near infrared region was 50% or more, and it was found that the sample had sufficient performance as a near infrared reflecting material. Further, the solar reflectance in the visible light region having a wavelength of 300 to 780 nm is 30 to 50%, and the reflectance is suppressed. Since the comparative sample G was white, all the wavelengths, visible light region, and near infrared region were about 78%.

(Coating composition test, solar reflectance measurement and evaluation)
Sample E and alkyd / melamine resin were mixed by a mill to obtain a coating composition (PWC = 50%, P / B = 1/1). This paint was applied with a # 60 bar coater and baked at 140 ° C. for 30 minutes to obtain a coating film.

  The color of this coating film was measured using a spectrocolorimeter SD5000 (manufactured by Nippon Denshoku Industries Co., Ltd.). In addition, the spectral reflectance (wavelength 300-2500 nm) was measured with an ultraviolet-visible near-infrared spectrophotometer V-670 (manufactured by JASCO Corporation, Spectralon (manufactured by Labsphere) as a standard reflector), and reflected by sunlight. Table 3 shows the result of the rate determined according to JISK5602. It was found that the solar reflectance in the near infrared region is 50% or more, and that it has sufficient performance as a near infrared reflecting material. Further, the solar reflectance in the visible light region having a wavelength of 300 to 780 nm is 30 to 50%, and the reflectance is suppressed.

(Acid resistance test and evaluation)
Table 3 shows the results of measuring the color and solar reflectance after the coating film was immersed in a 5% aqueous sulfuric acid solution for 1 week. The difference ΔE between the L value before and after the test was 0.37, which proved to be strong against acid.

  The present invention is a rutile-type titanium dioxide pigment having a green chromatic color, and has a sufficiently high near-infrared reflectance, so that it can be used in various places as a near-infrared reflective pigment.

Claims (4)

Containing from 1 to 50 mol% of cobalt element, an average particle diameter of 0.4～1.0Myuemu, Ri der solar reflectance is 50% or more in the near-infrared region (wavelength 780～2500Nm), moreover A near-infrared reflective material, which is a chromatic rutile titanium dioxide pigment having a solar reflectance of visible light (wavelength 300 to 780 nm) of 70% or less . The near- infrared reflecting material according to claim 1, wherein the solar reflectance in the near-infrared region is 60 to 80%. Paint composition you containing a near infrared ray reflecting material according to claim 1 or 2. Claim 1 or tree fat composition you containing a near infrared ray reflecting material according to 2.

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