JP5413554B2 - Coloring pigment for sunlight high reflection paint - Google Patents

Description

  The present invention efficiently reflects sunlight in the wavelength region from visible light to infrared light, that is, 380 to 780 nm and 780 to 2100 nm, thereby enabling roofing materials and asphalt roads generated under strong sunlight in summer. Coloring of the structure where colored iron oxide fine particles are fixed to the sea-island pattern on the surface of white inorganic pigment particles that can suppress heat island phenomenon by reducing heat storage on the exterior walls of buildings and the like, and at the same time, color in harmony with the environment The present invention relates to a colored pigment for highly reflective solar light paints, which has both light reflectivity and colorability functions.

The heat island phenomenon brought to urban areas by strong sunlight in the summer is a serious social problem that the demand for electric power for cooling is drastically increased, and the exhaust heat from the air conditioner further amplifies the heat island phenomenon. Therefore, many countermeasures such as heat-shielding pigments and paint compositions have been proposed in order to reflect sunlight and reduce heat storage in roads and buildings.

These proposals relate to paints and coating films using heavy metal-containing inorganic pigments or organic pigments or pigments having a light reflecting function, methods for increasing the light reflecting effect by the structure and combination of coating films, or white bodies. The present invention relates to a heat-shielding and highly reflective coating in which organic pigments or organic pigments are coated on the surface of white organic or inorganic particles using the characteristic of totally reflecting light rays.

As an example of utilizing a white body, the surface of white inorganic particles is coated with an organosilane compound generated from alkoxysilane, and a heat shielding pigment composed of composite particles in which perylene black is adhered to the coating (Patent Document) 1) is a particle having a structure in which a white particle surface of precipitated barium sulfate or titanium oxide is coated with an organosilane compound, and perylene black is adhered thereon.

In addition, “a composite pigment formed by coating a white pigment with a chromatic color pigment or a black pigment having near infrared reflectivity and / or near infrared transmittance reflects without absorbing near infrared rays and uses this as a colorant. It is noted that a building or the like to which a paint is applied is difficult to reach a high temperature due to direct sunlight ”(Patent Document 2 [0007]), and this composite pigment is a white inorganic or organic powder as a white pigment. For example, white pigments such as titanium oxide and zinc white, extender pigments such as calcium carbonate, alumina, silica, clay, activated clay, hydrous silicic acid, anhydrous silicic acid, aluminum powder, stainless steel powder, and organic plastic pigments (patent document) 2 [0015]), etc. “Near infrared non-absorbing dyes include, for example, azo, anthraquinone, phthalocyanine, perinone and perylene. Indigo / thioindigo, dioxazine, quinacdolin, isoindolinone, isoindoline, diketopyrrolopyrrole, azomethine, and azomethine azo organic dyes. Preferred azo dyes include azo, azomethine azo, Pigment particles having a structure in which a white pigment is coated with an organic dye such as “perylene-based organic black dye” (Patent Document 2 [0009]).

Patent Document 3 relates to “colored paint excellent in heat-shielding and chipping resistance” (Patent Document 3 [0001]), and pigment (a1) and pigment (a2) are included in the heat-shielding pigment (A). is there.
“Thermal pigment (A) is an azo, anthraquinone, phthalocyanine, perinone / perylene, indigo / thioindigo, dioxazine, quinacdrine, isoindolinone, isoindoline, diketopyrrolopyrrole, A pigment (a1) ”(Patent Document 3 [0009]) obtained by coating a white pigment with at least one infrared reflective pigment selected from azomethine and azomethine azo, and is used in“ pigment (a1) ”. The white pigment is a white inorganic or organic powder, for example, white oxide such as titanium oxide (rutile type titanium oxide, anatase type titanium oxide, etc.), lead white, zinc white, zinc sulfide, lithopone, calcium carbonate, Barium sulfate, alumina, silica, clay, activated clay, hydrous silicic acid, anhydrous silicic acid, aluminum powder, stainless steel powder A like extender pigments such as organic plastic pigments "(Patent Document 3 [0010]), pigment (a1) is these white pigments are pigment particles of the structure coated with the above organic dye.
“Thermal pigment (A) includes at least one selected from oxides, double oxides, carbides and nitrides of elements selected from Si, Zr, Mg, Ca, Fe and Mn, and white pigments. (Patent Document 3 [0017]) ”, the pigment (a2) is a particle having a structure in which a white pigment is coated with the above-mentioned inorganic element compound. It has been shown.

  As described above, an infrared reflective pigment composed of particles having a structure in which a surface of a white inorganic pigment is coated or adhered with an infrared reflective pigment or an organic dye is disclosed. As these examples show, in order to obtain a coating material that exhibits heat-shielding properties and near-infrared reflection effects, in many cases, organic dyes and organic pigments are currently used.

JP 2004-10851 A JP 2002-249676 A JP-A-2005-97462 Kazuhiko Tonooka, “Related Technologies for Cool Glass that Reflects Solar Heat”, Haruka, Japan Measuring Instruments Industry Association, January 15, 2008, No. 88, p. 12-15

  However, these organic pigments and thermal barrier paints using organic pigments generate a large amount of waste materials mixed with organic matter when repairing buildings and repairing roads where they are applied. There is a problem of how the organic matter affects the environment. It cannot be said that there is sufficient consideration for environmental conservation and harmony necessary for heat island countermeasures. There is a need for environmentally friendly heat island countermeasures.

  Patent Documents 2 and 3 mention clay and activated clay clay pigments as white inorganic pigments, but there is no description or suggestion of light reflection characteristics. It is merely an example.

  Further, a measure aimed at reflecting near-infrared rays in solar rays is that the energy distribution of solar rays is 48% in the infrared region, 46% in the visible light region, and 6% in the ultraviolet region (non-patent document). From 1), there are insufficient measures for the visible light region.

  Then, this invention makes it a technical subject to obtain the coloring pigment for sunlight highly reflective coating materials which has the function of light reflectivity and coloring property.

  In view of the current state of the prior art as described above, the present inventor has started an effort focusing on environmental adaptability from the visible light to the infrared region. As a result of intensive studies on the light reflectance characteristics of kaolin, diatomaceous earth, etc., they have found that they have high light reflection performance in the wavelength region from visible light to infrared light.

  The present invention was completed by finding that a colored pigment having a structure in which iron oxide fine particles were fixed in a sea-island pattern on the surface of a white inorganic pigment such as kaolin or diatomaceous earth had a high light reflectance even in the visible light region. . This is because iron oxide has a property of absorbing light of a specific wavelength and thus has a low light reflectivity, but this light absorption is weakened.

  This is clear from the measurement results of the light reflectance, but this phenomenon has not been fully elucidated. As a consideration, red iron oxide absorbs light in the vicinity of 850 nm, and yellow hydrous iron oxide has the property of absorbing light in the vicinity of 650 nm and 900 nm. Since this is a colored pigment made of islands of iron oxide fine particles or hydrous iron oxide fine particles scattered in the inorganic pigment sea, the reflected light on the surface of the white particles interferes with the absorbed light of the iron oxide fine particles that are in close contact with each other. However, it is thought that this is because the light absorption of the iron oxide fine particles or the hydrous iron oxide fine particles is weakened and the reflected light of the adjacent wavelength is enhanced.

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

  That is, the present invention is a colored pigment composed of particles having a structure in which iron oxide fine particles are fixed in a sea-island pattern on the surface of white inorganic pigment particles, and the light reflectance based on JIS A5759 is a wavelength region of 600 to 2100 nm. It is a coloring pigment for sunlight highly reflective paints characterized by being 40 to 90% (Invention 1).

  Further, the white inorganic pigment has an average particle diameter of 0.1 to 10 μm, and has a whiteness of 60% or more based on JIS Z8722, and is 1 of clay, talc, kaolin, diatomaceous earth, titanium oxide, zinc white, and barium sulfate powder. It is a coloring pigment for solar highly reflective paints of this invention 1 which is a seed or 2 or more types of mixed powder (this invention 2).

  Moreover, the iron oxide fine particles are red-type iron oxide or yellow-type hydrous iron oxide and have a mean particle size of 10 to 300 nm.

  The colored pigment for solar reflective coating according to any one of the present inventions 1 to 3, wherein the fixed amount of the iron oxide fine particles or the hydrous iron oxide fine particles is 5 to 70 wt% of the white inorganic pigment (Invention 4). ).

  The colored pigment for solar highly reflective paint according to the present invention is a colored pigment composed of particles having a structure in which iron oxide fine particles are fixed in a sea-island pattern on the surface of white inorganic pigment particles, and has both high solar reflectivity and chromaticity. Demonstrate the function.

  Moreover, since the light reflecting function of the present invention reflects 40 to 90% of sunlight in a wide wavelength range from visible rays to infrared rays, the paint using this pigment has a great effect of reducing heat storage due to solar radiation of the building. In addition, the colorability exhibits the effect of maintaining the scenery of the building street as a chromatic pigment.

  In addition, the material of the colored pigment according to the present invention uses clay-based materials such as clay and kaolin, white inorganic pigments such as titanium oxide and zinc white, and iron oxide as the color pigment, so it is applied to buildings and roads. Even after repairing, waste materials generated by renovation and repair work do not contain environmental pollutants, which can contribute to environmental conservation and harmony.

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

  The present invention is a colored pigment comprising particles having a structure in which iron oxide fine particles are fixed in a sea-island pattern on the surface of a white inorganic pigment particle, and the light reflectance based on JIS A5759 is 40 in the wavelength region of 600 to 2100 nm. It is a colored pigment for sunlight highly reflective paint characterized by ˜90%.

  The reason why the particles having a structure in which iron oxide fine particles are fixed in a sea-island pattern on the surface of the white inorganic pigment particles is to increase the reflection effect of sunlight. When the entire particle surface of the white inorganic pigment is coated with iron oxide fine particles, the light reflection effect intended by the present invention does not appear due to the inherent light absorption of iron oxide.

  The iron oxide fine particles are firmly fixed to the particle surface of the white inorganic pigment, and 5 to 70 wt% of the iron oxide fine particles are fixed to the sea-island pattern to such an extent that the light reflection function on the particle surface of the white inorganic pigment is not hindered. In this case, a colored pigment for solar highly reflective paint that exhibits a function of highly reflecting light rays is obtained for the first time.

  FIG. 1 is a schematic diagram showing the particle structure of the sea-island pattern of the color pigment of the present invention. In FIG. 1, WP is a white inorganic pigment, and CP in the sea WP is iron oxide fine particles and is represented as dotted islands, but the particle shape is an example.

  Moreover, the light reflectance based on JIS A 5759 of the coloring pigment according to the present invention is 40 to 90% in the wavelength region of 600 to 2100 nm. The reflection region is 600 to 780 nm in consideration of the frequency of 780 to 2100 nm, which is an infrared wavelength region with good reflection efficiency in consideration of solar thermal energy distribution. Further, the reason why the light reflectance was set to 40 to 90% was considered to be insufficient from the viewpoint of sunlight utilization when it was less than 40% and when it exceeded 90%. In the present invention, the light reflectance is particularly preferably 60% or more in the wavelength region of 780 nm to 1500 nm. A more preferable range of light reflectance is 50 to 85%, and still more preferably 60 to 80%.

  If an example is shown, the coloring pigment for solar reflective coatings of this invention can be manufactured by the following methods.

That is, a white inorganic pigment is dispersed in water, a ferrous salt aqueous solution is added to the slurry, and ferrous ions are adsorbed on the particle surface of the white inorganic pigment. Ions are fixed to the sea-island structure as precipitates, then the fixed precipitates are oxidized by heating to form yellow iron oxide particles, fixed to 5 to 70 wt% on the surface of the white inorganic pigment particles, and washed with water according to a conventional method. After filtration and separation, it can be obtained by drying and pulverizing.
In addition, the yellow colored pigment dry matter in which the yellow iron oxide fine particles are fixed to the sea-island structure on the surface of the white inorganic pigment particles is heated in the air to develop a red, purple, or brown color to be multicolored. be able to.

  First, the white inorganic pigment WP is dispersed in water to prepare a uniformly dispersed aqueous solution having a desired concentration.

  As this white inorganic pigment WP, clay, talc, kaolin, diatomaceous earth, titanium oxide, zinc white, and barium sulfate powder having an average particle size of 0.1 to 10 μm and a whiteness of 60% or more based on JIS Z8722 1 type, or 2 or more types of mixed powders can be used.

  When the average particle size of the white inorganic pigment in the present invention is less than 0.1 μm, the light reflectivity is inferior, and when it exceeds 10 μm, it becomes difficult to form a paint. The preferable average particle diameter of the white inorganic pigment is 0.5 to 8.0 μm, and an even more preferable range is 1.0 to 6.0 μm. The white inorganic pigment used is preferably a clay-based white inorganic pigment in consideration of economy and environmental harmony.

  The white inorganic pigment in the present invention preferably has a whiteness based on JIS Z8722 of 60% or more. When the whiteness is less than 60%, it is difficult to say that the resulting color pigment has sufficient light reflectivity.

  Next, a desired amount of a ferrous salt aqueous solution having a desired concentration prepared in advance is added to the aqueous dispersion of the white inorganic pigment WP, and the mixture is stirred and mixed.

  As the ferrous salt, ferrous salts such as ferrous sulfate, ferrous chloride, and ferrous nitrate can be used.

  Next, alkali is added to the above mixed aqueous solution, and ferrous ions in the aqueous solution are precipitated and fixed on the surface of the WP particles of the white inorganic pigment, and then the aqueous suspension is heated with stirring to obtain a desired An oxidation reaction is performed by blowing air at a temperature to fix the iron oxide hydrous particles CP on the surface of the white inorganic pigment WP particles. The product is washed with water, separated into solid and liquid, dried, and pulverized to obtain a yellow colored pigment for solar reflective coating.

  Further, the yellow pigment powder is heated and fired in the air, whereby a colored pigment for a sunlight-based highly reflective paint is obtained.

  When various conditions are changed in the above production method, a color pigment having a color tone other than yellow and red can be obtained.

  Further, the iron oxide fine particles CP obtained by the above production method are iron oxide or hydrous iron oxide particles having an average particle diameter of 10 to 300 nm. If the average particle size is less than 10 nm, the crystallinity of the particles is incomplete and the color developability is unstable, and if it exceeds 300 nm, it is difficult to fix to the surface of the white inorganic pigment WP. A preferable range of the average particle diameter is 30 to 250 nm, and a more preferable range is 50 to 200 nm. In addition, composite iron oxide particles containing different metals can be used in the same manner, which is preferable for increasing the color.

  Moreover, the fixed amount of the iron oxide particles CP is 5 to 70 wt% of the white inorganic pigment WP. If the fixing amount is less than 5 wt%, the colorability is insufficient, and if it exceeds 70 wt%, the colorability is improved, but the light reflectivity is lowered, which is not preferable. The more preferable range of the fixed amount of the iron oxide particles CP is 10 to 60 wt%, and still more preferably 10 to 50 wt%.

  Hereinafter, the present invention will be described in more detail with reference to examples.

  The observation of the particle form was performed using a scanning electron microscope (Hitachi, S4800).

  An X-ray diffraction apparatus (RINT 2500, manufactured by Riken Denki) was used.

  The color tone and light reflectance were measured using a coating film applied to mirror-coated paper by a pigment test method. The color tone was measured using a color difference meter (manufactured by X Light), and the light reflectance was measured using a spectrophotometer (manufactured by Hitachi, U-4100, self-recording spectrophotometer).

  Examples of white inorganic pigments include kaolin (manufactured by Junsei Kagaku, whiteness: 80 or more, average particle size 4 μm), diatomaceous earth (manufactured by Showa Chemical Industry, Radiolight # 900, whiteness: 85 or more, average particle size 6.5 μm). And titanium oxide (Ishihara Sangyo, rutile type, whiteness: 90 or more, average particle diameter 0.8 μm) was used.

  In the synthesis experiment, a reaction apparatus comprising a 500 ml flask equipped with a water bath, a stirrer, an air blowing apparatus, and a temperature controller was used.

  In all cases, ion-exchanged water was used.

Synthesis of sea-island structure particles-synthesis reaction example 1
Synthesis reaction: 6 g of kaolin powder and water were put into a 500 ml glass beaker to prepare a mixed solution of 300 ml in total volume, followed by dispersion treatment for 30 minutes using a homomixer to obtain a milky white kaolin dispersion. Next, the dispersion was transferred to a flask of a reaction apparatus, and while stirring, 100 ml of an aqueous solution prepared by dissolving 3.3 g of ferrous sulfate prepared in advance was added and stirred and mixed for 30 minutes. 100 ml of an aqueous solution in which 1.54 g of sodium carbonate was dissolved was added. The aqueous solution at this time had a pH of 8.37 and changed from milky white to green. Further, after stirring for 30 minutes, the aqueous solution was heated to a temperature of 40 ° C., and air was passed through the aqueous solution for 120 minutes to carry out an oxidation reaction. The green aqueous solution turned yellow to produce hydrous iron oxide particles.
Purification treatment: The obtained yellow precipitate was washed with water and purified, and then the solid substance obtained by filtration and separation was dried and pulverized, and the hydrous iron oxide fine particles were fixed to the kaolin particles in a 18.5 wt% sea-island structure. A colored pigment was obtained.

Examples 2 to 5 and Comparative Example 1
The synthetic reaction was carried out under the same conditions as in Example 1 except that the fixing ratio of the colored iron oxide particles to the white inorganic pigment was changed and the white inorganic pigment was changed to diatomaceous earth and titanium oxide.
Example 2: The fixing ratio was changed to 55 wt%, Example 3: the fixing ratio was changed to 15 wt%, Example 4: the white inorganic pigment was changed to diatomaceous earth, and Example 5: the white inorganic pigment was changed to titanium oxide. In the same manner as in Example 1, a colored pigment was obtained.
As Comparative Example 1, a yellow iron oxide pigment (STY-1 manufactured by Toda Kogyo) was used.

Synthesis of Sea-island Structure Particles-Heating Coloring Examples 6-8 and Comparative Example 2
Coloring by heating: Using the yellow colored pigment obtained in Examples 1, 4, and 5 as a precursor, the colored pigment is colored by heating in air, and iron oxide particles are fixed to the sea-island structure on white inorganic pigment particles. Got. The precursors are Example 6: Example 1, Example 7: Example 4, Example 8: Example 5. Further, as Comparative Example 2, a red iron oxide pigment (ED130 manufactured by Toda Kogyo) was used.

Measurement Analysis Results a) Particle Morphology The particle morphology of the synthesized product obtained in Example 1 is shown in FIG. It can be confirmed from FIG. 7 that the island has a sea-island structure. Further, the adhering elongated fine particles were hydrous iron oxide as a result of X-ray analysis. The average particle size of the hydrous iron oxide adhering was 120 nm. The result observed about the compound obtained in Examples 2-5 was also the same. In addition, in the color products obtained in Examples 6 to 8, a sea-island structure inheriting the particle form of the precursor was observed, and the adhered fine particles were hematite from the result of X-ray analysis. The average particle diameter of the fixed iron oxide (hematite) was 100 nm.

b) Color tone The color tone of the colored pigment obtained in Example 1 was L *: 65.7, a *: 20.1, b *: 53.1, and was a bright yellow powder.

  The color pigments obtained in other Examples and the color tones of Comparative Examples are shown in Table 1.

c) Light reflectivity The light reflectivity curves of Examples 1 and 6 are shown in FIGS. 2 and 3, and the light reflectivity curves of Comparative Examples 1 and 2 are shown in FIGS.

  In addition, when the light reflectance was measured about the colored pigment obtained in Examples 2-5, it was confirmed that it is comparable as the said Example 1. Moreover, when the light reflectance was measured about the coloring pigment obtained in Example 7, 8, it was confirmed that it is comparable as the said Example 6.

  From these figures, it is clear that the yellow color pigment Examples 1 to 5 and Comparative Example 1 are compared, and the red color pigment Examples 6 to 8 and Comparative Example 2 are compared. In all the examples, high reflectivity characteristics of 60 to 80% were exhibited from the visible light region (380 to 780 nm) to the near infrared region (780 to 1200 nm).

  FIG. 6 is a light reflectance curve of kaolin, a white inorganic pigment.

  The reflectance curve in FIG. 6 confirms that the colored pigment of the sea-island structure of the present invention is a highly reflective solar pigment that brings together the light reflection characteristics of the white inorganic pigment and the colorability of the iron oxide fine particles. Met.

  The present invention is a color pigment for solar highly reflective paint as a heat island countermeasure material that meets the demands of the times of energy saving, resource saving and environmental conservation, and the material used is environmentally friendly and economical. It can be expected to be used for a wide range of applications besides building materials and road paving.

The schematic diagram which shows the sea-island structure of the coloring pigment concerning this invention. Light reflectance curve of the color pigment obtained in Example 1 Light reflectance curve of the color pigment obtained in Example 6 Light reflectance curve of Comparative Example 1 (yellow iron oxide pigment) Light reflectance curve of Comparative Example 2 (red iron oxide pigment) Kaolin's light reflectance curve Scanning electron micrograph of the color pigment obtained in Example 1

Explanation of symbols

FIG.
WP: White inorganic pigment CP: Fine iron oxide particles

Claims (3)

A colored pigment composed of structural particles in which iron oxide fine particles are fixed in a sea-island pattern on the surface of white inorganic pigment particles having an average particle size of 0.1 to 10 μm , wherein the iron oxide fine particles are red iron oxide or yellow Based hydrous iron oxide with an average particle size of 10 to 300 nm, JIS
A color pigment for solar highly reflective paint, wherein the light reflectance based on A5759 is 40 to 90% in a wavelength region of 600 to 2100 nm. The white inorganic pigment is one or a mixture of two or more of clay, talc, kaolin, diatomaceous earth, titanium oxide, zinc white, and barium sulfate powder having a whiteness of 60% or more based on JIS Z8722. The coloring pigment for solar highly reflective coatings as described. The coloring pigment for solar reflective coating according to claim 1 or 2, wherein the fixed amount of the iron oxide fine particles or the hydrous iron oxide fine particles is 5 to 70 wt% of the white inorganic pigment.