JP2004027241A - Thermal insulation coating and its coating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal insulation coating having excellent reflecting properties in a near-infrared range even if the coating is black or dark chromatic color near black, capable of preventing a coated film from temperature rise and having excellent weather resistance. <P>SOLUTION: This thermal insulation coating comprises a vehicle of excellent weather resistance and a pigment having 15% or more of reflectance of solar radiation defined by JIS A 5759 and 24 or less of L* value in a color space of L*, a* and b* of CIE 1976. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a heat-shielding paint having a shielding effect against solar heat and the like, and a coating method thereof. More specifically, the present invention relates to a heat-shielding paint that exhibits low weather absorption even for a dark-colored paint and therefore exhibits excellent weather resistance, and a method of applying the same.

From the viewpoint of energy saving, etc., many proposals have been made on heat-shielding paints having a shielding effect against solar heat or the like. However, most of them are limited to white or near light colors, and not to black or near dark colors. Pigments such as carbon black and iron black are usually used for dark-colored paints.However, compared to light-colored paints, these pigments easily absorb sunlight in a wide wavelength range from the ultraviolet to the near infrared. The temperature rises indoors through the membrane. Further, thermal degradation of the resin in the coating film causes chalking, discoloration and the like of the coating film. These phenomena are particularly pronounced in dark and matte coatings.

As a conventional technique relating to black or dark colored heat-shielding paints, two or more of red, orange, yellow, green, blue, and violet pigments exhibiting high reflectance in the ultraviolet and near-infrared regions are additively mixed. (Patent Literature 1) discloses a technique for making the Munsell symbol N-1 black. With this technology, a coating film that does not show absorption in the near-infrared region can be obtained and the temperature rise can be suppressed.On the other hand, since the weather resistance of each additive color-mixed pigment is different, a pigment with weak weather resistance during use can be used. There is a problem that the color of the entire coating film changes from the original black color to purple, green, orange, or the like due to discoloration. Further, it is extremely difficult to adjust black of the Munsell symbol N-1 by additive color mixture.

JP-A-4-255768

As described above, the conventional heat-shielding paint of black or dark color was insufficient in terms of weather resistance and color retention, and it was difficult to adjust the hue of the paint. Therefore, the present invention provides a novel heat-shielding paint having excellent reflection characteristics in the near-infrared region even if it is a black or dark-colored paint, thereby preventing a rise in temperature of the coating film and having excellent weather resistance. It is. It is another object of the present invention to provide a coating method capable of more effectively exhibiting the weather resistance of the heat-shielding paint.

た め In order to solve the above problems, the present invention is characterized in that a paint containing a pigment that absorbs in the visible region and reflects in the near infrared region and a vehicle having excellent weather resistance are provided.

Further, the present invention is characterized in that the pigment has a solar reflectance of 15% or more as defined in JIS A # 5759 and an L * value of 24 or less in a CIE1976 L * a * b * color space. And

{Further, the present invention is characterized in that the content of the pigment is 7 to 110 parts by weight based on 100 parts by weight of the resin solid content of the paint.

{Furthermore, the present invention is characterized in that, in addition to the pigment, at least one or more color pigments having a solar reflectance of 12% or more defined in JIS A 5759 and a white pigment.

The pigment, which absorbs in the visible region and reflects in the near-infrared region, the content of the color pigment, and the content of the white pigment are 7 to 110 parts by weight, It is preferably from 100 to 100 parts by weight and from 40 to 230 parts by weight.

チ タ ン A titanium oxide pigment is preferably used as the white pigment.

Furthermore, the heat-shielding paint of the present invention is characterized in that the pigment contained therein has an average particle diameter of 50 μm or less.

Furthermore, the present invention is characterized by containing a ceramic balloon and a structure retaining agent. Thereby, high reflection performance can be obtained, and functions such as heat insulation and waterproofness can be provided.

The vehicle having excellent weather resistance used in the present invention includes at least one of an acrylic resin, a polyester resin, a silicon-modified polyester resin, a silicon-modified acrylic resin, an alkyd resin, a vinyl chloride resin, and a fluororesin, and if necessary, an isocyanate. And at least one melamine resin.

Further, the present invention is a method for applying a heat-shielding paint, which comprises applying the above-mentioned heat-shielding paint so that the coating thickness becomes 8 μm or more, and applying an undercoat and / or an overcoat as required. . By applying the undercoat and / or the overcoat, the durability, weather resistance, stain resistance and the like of the whole coating film can be further improved.

As described above, according to the present invention, it was possible to obtain a paint having excellent reflection characteristics in the near-infrared region and having low heat energy absorption and excellent weather resistance while being black or a dark color close thereto. Further, the coating method of the present invention can most effectively bring out the excellent weather resistance of the paint.

Hereinafter, embodiments of the present invention will be described in detail.
The paint of the present invention is characterized by using a pigment that absorbs in the visible region and reflects in the near-infrared region (hereinafter referred to as a dark-colored reflective pigment). Since it shows absorption in the visible region, it exhibits dark colors such as black and dark brown, similarly to conventional carbon black and the like. However, since there is no light absorption in the near-infrared region and high reflectivity, there is no absorption of heat energy, so that a rise in the temperature of the coating film can be prevented. Therefore, thermal deterioration of the coating film can be suppressed.

As the above-mentioned dark-colored reflective pigment, any pigment that absorbs in the ultraviolet and visible regions and reflects in the near-infrared region can be used without any particular limitation. Among them, JIS A-5759 Architectural heat ray shielding And a pigment having a solar reflectance of 15% or more in a 350 to 2100 nm region defined by the glass shatterproof film is preferably used. In addition, the solar reflectance data of this patent is measured in a sufficiently concealed state, specifically, a coating film having a concealment ratio of about 1.0.

濃 Further, as the deep-colored reflective pigment, those having a solar reflectance of 15% or more and an L * value of 24 or less in a CIE1976 L * a * b * color space are used. An L * value of 24 or less means a black color or a dark color close to it. Specific examples of the pigment satisfying the above conditions include azomethiazo pigments manufactured by Chromo Fine Black A-1103 (trade name, manufactured by Dainichi Seika Kogyo Co., Ltd.), and calcined pigments.

The content of the dark reflective pigment in the paint can be appropriately set in consideration of the use of the paint, weather resistance, etc. However, if the content is small, the hiding power is insufficient, and the role of the original aesthetic of the paint is insufficient. When the content is too high, the coating tends to be brittle and the cost increases. Parts are preferred.

Furthermore, the heat shielding paint of the present invention is characterized by using a vehicle having excellent weather resistance. The vehicle excellent in weather resistance as referred to herein means a vehicle excellent in yellowing resistance, color retention, gloss retention, chemical resistance, chalking resistance, etc., water-soluble type and solvent type, or at room temperature. Both a drying type and a baking type can be used. By using such a vehicle together with the above-mentioned dark reflective pigment, excellent weather resistance of the entire coating film can be obtained.

As specific examples of the above-mentioned vehicle having excellent weather resistance, the main components thereof were acrylic resin, polyester resin, silicon-modified polyester resin, silicon-modified acrylic resin, alkyd resin, vinyl chloride resin, and fluorine-based resin. Among them, polyester resins and fluorine-based resins are preferably used. If necessary, a curing agent such as various isocyanates and melamine resins can be used.

In the paint of the present invention, in addition to the above-mentioned dark reflective pigment, at least one or more coloring pigments excluding conventional black pigments such as carbon black and iron black, and white pigments (hereinafter, referred to as coloring pigments and the like) Can be contained. The white pigment may be used as needed. Therefore, as a pigment other than the deeply colored reflective pigment, a case of using only a colored pigment and a case of using a colored and white pigment are applicable. By containing coloring pigments and the like, paints of various colors can be adjusted. Compared to a conventional case where a black pigment such as carbon black is mixed, the coating film absorbs less heat energy, so that discoloration and the like hardly occur.

As the above-mentioned coloring pigment, various kinds of commonly used pigments can be applied. Among them, pigments having a solar reflectance of 12% or more in a 350 to 2100 nm region defined in JIS A # 5759 are preferably used. It should be noted that the solar reflectance data of this patent is measured on fully concealed coatings. Examples of the coloring pigment satisfying this condition include yellow pigments such as monoazo yellow (trade name Hoster Palm Yellow H3G: manufactured by Hoechst Co., Ltd.), iron oxide (trade name: Todacolor 120ED, manufactured by Toda Kogyo Co., Ltd.), Red pigments such as quinacridone red (Hostaperm Red E2B70: manufactured by Hoechst Co., Ltd.), blue pigments such as phthalocyanine blue (trade name: Cyanin Blue SPG-8: Dainippon Ink Co., Ltd.), and phthalocyanine green (trade name) Green pigments such as cyanine green 5310 (manufactured by Dainichi Seika Kogyo Co., Ltd.).

Also, the white pigment is not particularly limited, and specific examples thereof include pigments such as titanium oxide and zinc white. Titanium oxide can be applied to both rutile type and anatase type, but rutile type titanium oxide is particularly preferably used.

The content in the case of using a combination of a dark reflective pigment and a colored pigment is 7 to 110 parts by weight of the dark reflective pigment and 7 to 110 parts by weight of the colored pigment with respect to 100 parts by weight of the resin solid content of the paint. , And 40 to 230 parts by weight of a white pigment. If the content is outside the above range, the concealing power is insufficient if the content is small, and the coating workability and durability are poor if the content is large.

(4) The content of the pigment as a whole is preferably 7 to 150 parts by weight based on 100 parts by weight of the resin solid content of the paint. If the content is less than the predetermined amount, sufficient hiding power of the coating film cannot be obtained, and sunlight and the like are easily transmitted, so that the temperature rises and causes deterioration of the coating film. On the other hand, if the film thickness is increased to obtain the hiding power, the coating workability is impaired, which is not suitable. Conversely, if the amount is larger than the predetermined amount, the pigment on the surface of the coating film is partially exposed, so that the smoothness is lowered, and the resistance to moisture, light, heat and the like is significantly impaired.

In the dispersing step for forming a paint, the degree of dispersion of the above-described dark-colored reflective pigments and colored pigments can be set according to the type of the paint, the use, etc., and is not particularly limited, but the average particle diameter is 50 μm. It is preferable that the particles be dispersed so as to be less than or equal to 10 μm. When the thickness is 50 μm or more, the surface of the coating film becomes uneven and the appearance is impaired, and dust and the like easily adhere to the rough coating film surface, and the coating film temperature easily rises, resulting in weather resistance, stain resistance, color stability, and the like. Is unsuitable because it deteriorates.

と し て It is preferable to use a medium other than iron as a dispersion medium used for dispersing the pigment. Iron dispersion media are unsuitable because they reduce the solar reflectance of the pigment due to color contamination. Specific examples of the dispersion medium other than iron include ceramics, glass beads, flint stone, and the like. Among them, glass beads are easily used and excellent in economical efficiency, and thus are preferably used. The particle size of the dispersing medium, the filling amount, the type of the pigment dispersing machine, etc. are not particularly limited. However, as a specific example of the embodiment, glass beads of 3 to 1.5 mm are filled to about 80% of the capacity of the sand grind mill. Can be mentioned.

熱 In addition to the pigment and the vehicle, the heat-shielding paint of the present invention may contain an aggregate having a reflecting function and a heat insulating function. Specific examples of the aggregate include hollow particles such as shirasu balloons, polystyrene balloons, and ceramic balloons. Since these aggregates have a reflecting function and a heat insulating function, they can further improve the heat shielding property and the weather resistance of the coating film in combination with the above-mentioned deeply colored reflecting pigment.

Among the above additives, silicon boride ceramic balloons and the like are preferably used because they can reflect sunlight and the like in the surface layer and in the shell, and are hollow and excellent in heat insulation. Further, the ceramic balloon is preferably used together with a structure retaining agent. The paint containing the ceramic balloon and the structure retaining agent described herein has already been proposed by the present inventors in Japanese Patent Application No. 10-130742. Since the ceramic balloon has a specific gravity of less than 1, when it is used alone, it tends to float on the surface of the coating, so that the solvent in the coating surface layer volatilizes, causing a so-called skinning phenomenon, which causes a problem of poor storage stability. However, by including the structure-retaining agent, structural viscosity is imparted to the paint, the balloon can be uniformly distributed, and the storage stability is improved. Further, since the coating film containing the balloon has water resistance, the overall weather resistance can be further improved.

The conditions applicable to the present invention, such as the type and content of the ceramic balloon and the structure-retaining agent, are the same as those disclosed in Japanese Patent Application No. 10-130742. In order to obtain more optimal weather resistance, the following conditions are preferably used. That is, the particle diameter of the balloon is preferably 5 to 110 μm. If it is larger than 110 μm, the coating film becomes uneven, which is not suitable. The particle size distribution is preferably 30 to 65 μm in a 50% cumulative area, and 50 to 110 μm in a 90% cumulative area. The specific gravity of the balloon is preferably from 0.16 to 0.6. Further, the strength of the balloon is preferably in the range of ^{20 to} 750 kgf / cm ² . If it is smaller than this range, the balloon is liable to be destroyed during the production of the coating material. Further, as the type of the structure retaining agent, a complex system of fatty acid amide / fine silica, a complex system of organic bentonite / fine silica, a complex system of fatty acid amide / organic bentonite / fine silica, a composite system of polyethylene oxide / fine silica, And those obtained by removing fine silica from the above composite system are preferably used.

塗料 Furthermore, the coating material of the present invention can contain various additives which are usually used. Specifically, color separation preventives, sedimentation preventives, surface conditioners, lubricants, plasticizers, defoamers, preservatives, antifreezes, hardeners, pigment dispersants, emulsifiers, desiccants, ultraviolet absorbers , Fungicides, antibacterial agents and the like.

素材 The material to which the above paint is applied is not particularly limited, and various materials such as wood, concrete, asbestos, metal, and resin can be selected. In addition, the application for application can be applied to places where it is desired to provide a heat-shielding function, for example, buildings such as houses, factories, cold storage warehouses, transportation vehicles such as cars, trains, benches, and freezing vehicles, storage tanks, tankers, and the like. Roof, ceiling, outer wall, inner wall, etc.

方法 The method of coating may be appropriately selected according to the purpose, and specific examples include brush coating, roller coating, spraying, and roll coater coating. Depending on the object to be coated, electrostatic coating, curtain coating, dipping, and the like are also applicable. Further, a method of drying and forming a coating film after application can be appropriately selected depending on the properties of the coating material, such as natural drying and baking.

膜厚 The thickness of the coating film can be appropriately set depending on the properties of the coating material and the material, but it is preferable to apply the coating so as to have a thickness of 8 μm or more, and more preferably 10 μm or more. When the thickness is less than 8 μm, the hiding power is insufficient, and when the ceramic balloon is contained, the balloon tends to be non-uniformly distributed and sufficient heat shielding performance cannot be obtained. On the other hand, if the thickness is too large, pinholes occur in the case of a baked paint, and in the case of a normal dry type, the paint sags.

Furthermore, when applying the paint of the present invention to a material, a primer can be applied in advance. The undercoating is performed for the purpose of preventing rust, improving the adhesion of the paint of the present invention to the material, and improving the adhesion to the overcoat, and a conventionally known undercoat can be appropriately used. As a specific type of the undercoat paint, a resin obtained by adding titanium oxide, a rust preventive pigment, an extender pigment, or the like to a resin such as an epoxy resin, an alkyd resin, an epoxy urethane resin, or a polyester resin is preferably used. The thickness of the coating film can be appropriately determined in consideration of the material, type of overcoat, required performance, and the like. By applying the undercoat, the adhesion of the paint of the present invention is enhanced, the durability of the coating film is improved, and the application range of the overcoat can be expanded.

後 に Furthermore, after applying the paint of the present invention, a top coat such as a stain prevention clear can be applied. The overcoating can improve the adhesion and water resistance of the coating film, and can prevent contamination by dust in the atmosphere and prevent a decrease in solar reflectance. Further, a glossy coating film can be provided. As the overcoat paint, acrylic-based, polyester-based stain-preventing clears and the like are applicable.In particular, an organic-inorganic composite resin to which an anti-UV agent is added or an extender pigment such as precipitated barium sulfate is dispersed and added, It has an excellent effect of preventing contamination and is suitably used. Further, the thickness of the overcoat is not particularly limited as long as it can completely cover the paint of the present invention, but is preferably about 5 to 50 μm.

The above-mentioned undercoat and overcoat can be applied alone or both. Further, an intermediate coating can be applied as necessary. The intermediate coating has the effect of improving corrosion resistance and imparting resistance to cracking, peeling, and the like of the coating because the coating is thick. What kind of coating system is used is appropriately selected in consideration of the application, required performance (durability, weather resistance), economy, and the like.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

1. Raw materials Table 1 shows the raw materials of the coating materials prepared in the examples.

2. Preparation of paint (1) After mixing the raw materials in the ratio shown in Table 2, first, resin L, solvent, and each pigment were mixed, resin N and defoamer Q were added to adjust the viscosity to 70 ± 5 KU to obtain G1 to G8. . The pigment was dispersed to 10 μm or less, and the dispersion medium used was glass beads having a particle size of 2.1 mm (trade name: Hibee D10). In the dispersion step, 500 g of the dispersion medium and 300 g of the premix paste were dispersed by using a table-top batch type SG mill.

(2) G1 to G8, resin, and the like were mixed at the ratios shown in Table 3 to obtain paint samples P1 to P3, C1, and C2.

3. Preparation of Test Plate Using the paints in Tables 2 and 3, test plates were prepared under the coating plate preparation conditions in Table 4. The undercoat paint is composed of an epoxy urethane resin, titanium oxide, a rust preventive pigment, and an extender pigment. The top coat is P3 in Table 3. Further, the coating method was performed by a bar coater, and the baking was performed by an electric convection oven. The printing conditions are as follows.
Undercoat Furnace temperature 150 ° C × 15 minutes Main paint Furnace temperature 150 ° C × 20 minutes Clear Furnace temperature 150 ° C × 20 minutes

4. Test method (1) Reflectance chart The wavelength dependence of the reflectance was measured using a spectrophotometer. The measurement results are shown in FIGS.
(2) Solar reflectance The solar reflectance of the coating film was measured as the solar reflectance in the range of 350 to 2100 nm defined in JIS A 5759. Table 4 shows the results.
(3) L * value L * in the CIE1976 L * a * b * color space was measured with a Karacom C-type spectrophotometer (manufactured by Dainichi Seika Kogyo Co., Ltd.). Table 4 shows the results.
(4) Coated plate temperature The coated plate temperature by lamp irradiation was measured. First, a U-shaped coated plate 1 as shown in FIG. 13 was molded, two molded products were arranged in the width direction, and a 200 W Toshiba reflex lamp was irradiated from a height of 130 mm from the coated plate. In addition, a, b, and c in FIG. 13 represent the dimensions of the molded product, and are a = 220 mm, b = 110 mm, and c = 45 mm, respectively. The temperature of the coated plate was measured by the temperature sensor 2 attached to the center of the back side of the coated plate. Since the temperature became almost constant 15 to 20 minutes after the start of lamp irradiation, the temperature after 20 minutes was used as the measured value. Table 4 shows the measurement results.
(5) QUV 1900 hours ΔE * was measured after irradiation with an accelerated exposure tester QUV for 1900 hours. Table 4 shows the measurement results.
(6) Carbon contamination test A 5% aqueous solution of carbon pigment is applied to the coating film, left at 20 ° C. for 24 hours, and gently rubbed with a sponge scourer while washing with water to remove carbon. The color difference before and after the test was measured as ΔL * value. Table 4 shows the measurement results.
(7) 5% NaOH test The test plate was immersed in a 5% NaOH aqueous solution at 20 ° C. for 24 hours, and the state of the subsequent coating film was observed. The observation results were evaluated according to the following criteria.
○ There is no abnormality. There is some blister in the coating film. X There is remarkable blister in the coating film. (8) Prepare 1 kg of paint with the composition shown in Table 5, put the paint in a container, and let it stand for 2 weeks. Observed. The results were evaluated according to the following criteria.
◎ Good with no balloon surface floating ○ Good balloon surface floating but no problem in practicality × Balloon surface floating and practically problematic

From the above results, it is clear that the coating material of the present invention can keep the coating plate temperature lower by 10 ° C. or more as compared with the case where the conventional black pigment is used, and is excellent in weather resistance from QUV measurement. Was. This is suggested from the fact that the paint of the present invention has a large reflectance in the near infrared region of the reflectance chart.

Also, as can be seen from E12 and E13 in Table 4, it is clear that the inclusion of the ceramic balloon and the structure retaining agent improves the reflection performance and the weather resistance.

Further, by comparing E7 and E8 and E9 and E11 in Table 4, it is clear that by applying a top coat such as a stain prevention clear, the stain resistance and weather resistance are improved.

Furthermore, from E16 in Table 4, it is clear that when iron is used as the dispersion medium, the thermal barrier properties deteriorate.

Also, from Table 5, it is clear that the structure retaining agent prevents the balloon from floating and greatly improves the storage stability.

It is a graph which shows the wavelength dependence of the reflectance in sample E1. It is a graph which shows the wavelength dependence of the reflectance in sample E2. It is a graph which shows the wavelength dependence of the reflectance in sample E3. It is a graph which shows the wavelength dependence of the reflectance in sample E4. It is a graph which shows the wavelength dependence of the reflectance in sample E5. It is a graph which shows the wavelength dependence of the reflectance in sample E6. It is a graph which shows the wavelength dependence of the reflectance in sample E7. It is a graph which shows the wavelength dependence of the reflectance in sample E12. It is a graph which shows the wavelength dependence of the reflectance in sample E13. It is a graph which shows the wavelength dependence of the reflectance in sample E14. It is a graph which shows the wavelength dependence of the reflectance in sample E15. It is a graph which shows the wavelength dependence of the reflectance in sample E16. It is a figure showing the irradiation method of a lamp.

Explanation of reference numerals

1 Painted plate 2 Temperature sensor a Molded product dimension b Molded product dimension c Molded product dimension

Claims (10)

(4) A heat-shielding paint comprising a pigment that absorbs in the visible region and reflects in the near-infrared region, and a vehicle having excellent weather resistance. 2. The pigment according to claim 1, wherein the pigment has a solar reflectance defined by JIS A-5759 of 15% or more and an L * value of 24 or less in a CIE1976 L * a * b * color space. The heat-shielding paint as described. (3) The heat-shielding paint according to (1) or (2), wherein the content of the pigment is 7 to 110 parts by weight based on 100 parts by weight of the resin solid content of the paint. 4. The ink composition according to claim 1, further comprising, in addition to the pigment, at least one color pigment having a solar reflectance of 12% or more as defined in JIS A-5759, and optionally a white pigment. The heat-shielding paint as described. The content of the pigment according to any one of claims 1 to 3, the color pigment, and the white pigment is 7 to 110 parts by weight, 7 to 110 parts by weight, and 40 to 100 parts by weight, respectively, based on 100 parts by weight of the resin solid content of the coating material. The heat-shielding paint according to claim 4, wherein the amount is 230 parts by weight. 6. The heat-shielding paint according to claim 4, wherein the white pigment is a titanium oxide pigment. (7) The heat-shielding paint according to any one of (1) to (6), wherein the pigment is dispersed in the paint to have an average particle size of 50 μm or less. 8. The heat-shielding paint according to claim 1, further comprising a ceramic balloon and a structure-retaining agent. A vehicle having excellent weather resistance is an acrylic resin, a polyester resin, a silicon-modified polyester resin, a silicon-modified acrylic resin, an alkyd resin, a vinyl chloride resin, and at least one of a fluororesin, and, if necessary, at least one of an isocyanate and a melamine resin. 9. The heat-shielding paint according to claim 1, comprising one or more kinds. (10) A method for coating a heat-shielding paint, comprising applying the heat-shielding paint according to any one of claims 1 to 9 so that the coating film thickness is 8 µm or more, and applying an undercoat and / or an overcoat as needed.

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