JP4132506B2 - Heat shielding multilayer coating - Google Patents

Description

【００４２】
【表２】

【００４３】
【発明の効果】
上記のように本発明によれば、熱遮蔽多層塗膜の少なくともプライマー層には、カーボンブラックを含まず、かつ３５０〜２５００ｎｍの波長領域におけるＪＩＳ Ａ ５７５９に準拠した光線反射率が２０〜９０％である塗料を使用しているため、十分な遮熱効果を示す。最外層部に熱遮蔽塗料を用いなくても、太陽光は、上層の塗膜を透過してプライマー層に達して、このプライマー層で太陽光を反射するために遮蔽効果が得られる。
【００４４】
また、最外層の塗装については熱遮蔽塗料を用いないで済むため、外観に影響を与えず、したがって自動車等、意匠が重要なファクターとなる物品に特に有用である。
【図面の簡単な説明】
【図１】本発明の熱遮蔽多層塗膜の一例を示す断面図である。
【図２】本発明に関する温度測定用試験ボックスの断面図である。
【符号の説明】
１ 基材
２ プライマー層
３ 裏面プライマー層
４ 中塗り層
５ 上塗り層
６ 本体
７ 枠
８ テストピース
９、１０、１１ 熱電対
１２ 温度計
１３ 赤外線ランプ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat-shielding multilayer coating film, for example, a heat-shielding multilayer coating film suitable for preventing an increase in temperature in an automobile due to sunlight.
[0002]
[Prior art]
If the car is left under the hot sun, the temperature inside the car rises. If an air conditioner is used to prevent this, the amount of gasoline used increases and the amount of CO ₂ gas emitted also increases. Such adverse effects of temperature increase due to sunlight or the like and energy consumption for the purpose of temperature suppression are the same not only in automobiles but also in ships such as warehouses, airplanes and tankers.
[0003]
In order to prevent the above temperature rise, various thermal barrier coatings have been proposed. For example, Japanese Patent Publication No. 59-31545 discloses a heat reflecting enamel containing a pigment such as nickel oxide and antimony trioxide in Japanese Patent No. 2593968. Discloses a black solar heat shielding coating composition that does not contain heavy metals.
[0004]
[Problems to be solved by the invention]
However, the heat reflective enamel and the solar heat shielding coating composition are considered to have no effect unless they are applied to the outermost surface of the coating that is exposed to sunlight. For this reason, it has been difficult to apply an article such as an automobile, in which the design (appearance) of the product is an important factor, because the paints that can be selected are limited. Therefore, the problem to be solved by the present invention is to provide a coating film that can exhibit a heat shielding effect without being formed on the outermost surface of the coating film.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the heat shielding multilayer coating film of the present invention is a multilayer coating film in which a primer layer, an intermediate coating layer and a top coating layer are sequentially formed on a substrate surface. not including, and light reflectance from 20% to 90% der conforming to JIS a 5759 in the wavelength range 350~2500nm is, a said primer layer is electrodeposited coating is formed on both sides of the substrate . Surprisingly, it has been found that by using a coating film having such a specific property as a primer layer, a sufficient heat shielding effect can be obtained without using a heat shielding paint in the outermost layer portion.
[0006]
The heat shielding multilayer coating film of the present invention can be suitably used for automobile bodies.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be specifically described with reference to FIG.
FIG. 1 is a sectional view showing an example of the heat shielding multilayer coating film of the present invention. The base material 1 is mainly a metal material, and examples thereof include steel materials such as galvanized steel used for automobile bodies, roofing materials, warehouse outer walls, and aluminum materials, but other plastics other than metals, tile materials, It can also be used for ceramics such as glass materials.
[0008]
In the present invention, a primer layer 2 having a heat shielding effect is formed on a substrate 1. The primer layer 2 may be only the surface of the substrate 1, but the heat shielding effect is further increased by providing the back primer layer 3.
[0009]
An intermediate coating layer 4 is formed on the primer layer 2, and a top coating layer 5 is formed thereon to constitute a heat shielding multilayer coating film. A top coat (not shown) may be further provided on the top coat layer 5, and a heat insulating layer for enhancing the heat shielding function is provided between the primer layer 2 and the intermediate coat layer 4. May be.
[0010]
The primer layer 2 (and the back primer layer 3), which is a feature of the present invention, does not contain carbon black, and has a property that the light reflectance in accordance with JIS A 5759 in the wavelength range of 350 to 2500 nm is 20 to 90%. Have. The layer having such properties can be obtained by applying a paint containing a pigment that reflects light in the above wavelength region.
As this pigment, a white pigment that reflects the entire wavelength region can be used. In addition, the light reflectance can be secured by subtractive color mixing by appropriately combining cyanine, magenta, and yellow pigments. In particular, a combination of a magenta pigment and a cyanine pigment is preferable because the light reflectance around the infrared region is remarkably increased.
[0011]
Any type of pigment may be used as long as it meets the above conditions. For example, iron oxide, lead oxide, strontium chromate, titanium dioxide, talc, barium sulfate, cadmium yellow, cadmium red Inorganic pigments such as chrome yellow and aluminum flakes, and organic pigments such as phthalocyanine blue and sinker red are exemplified. Of course, carbon black is not included in this.
When the pigment content in the paint is expressed as a weight ratio of pigment: non-volatile content in the paint, a range of 0.05 to 1: 1 is preferable.
[0012]
Examples of the vehicle used for dispersing the pigment include conventionally known acrylic resins, epoxy resins, polyamide resins, polyurethane resins, polyester resins, polybutadiene resins, and modified products of these resins. In addition, any of solvent type, water dispersion type, emulsion type and the like can be used.
In addition, any coating method such as spray coating, brush coating, dip coating, roll coating, and flow coating can be used.
[0013]
However, when the heat-shielding multilayer coating film of the present invention is applied to an automobile, the primer layer 2 (and the back primer layer 3) is preferably formed of a cationic electrodeposition paint. In this case, the vehicle is preferably a cation-modified epoxy resin in terms of corrosion resistance and throwing power, and the resin is used as a water-soluble paint by neutralizing with an acid.
[0014]
The cation-modified epoxy resin is cationized by opening the epoxy ring of the epoxy resin with amines such as primary amine, secondary amine, or tertiary amine.
[0015]
Examples of the epoxy resin as a starting material include polyphenol polyglycidyl ether type epoxy resin which is a reaction product of a polycyclic phenol compound such as bisphenol A, bisphenol F, bisphenol S, phenol novolak, cresol novolak and epichlorohydrin. It is done.
This resin can be used by extending the chain with a bifunctional polyester polyol, polyether polyol, bisphenol, dibasic carboxylic acid or the like.
[0016]
Similarly, prior to the ring-opening reaction of the epoxy ring with amines, 2-ethylhexanol, nonylphenol, ethylene glycol mono-monomer for some epoxy rings for the purpose of adjusting the molecular weight or amine equivalent and improving heat flow. Monohydroxy compounds such as 2-ethylhexyl ether and propylene glycol mono-2-ethylhexyl ether can also be added and used.
[0017]
Examples of amines that can be used in opening an epoxy ring and introducing an amino group include butylamine, octylamine, diethylamine, dibutylamine, methylbutylamine, monoethanolamine, diethanolamine, N-methylethanolamine, triethylamine And primary, secondary or tertiary amines such as N, N-dimethylethanolamine. The tertiary amine can be used in the form of a salt with an acid used as a neutralizing agent.
[0018]
A ketimine block primary amino group-containing secondary amine such as aminoethylethanolamine methyl isobutyl ketimine can also be used. These amines must be reacted with at least an equivalent equivalent to the epoxy ring in order to open all the epoxy rings.
[0019]
The number average molecular weight of the cation-modified epoxy resin is preferably in the range of 1500 to 5000. When the number average molecular weight is less than 1500, the cured coating film may be inferior in physical properties such as solvent resistance and corrosion resistance. On the other hand, when it exceeds 5000, the viscosity of the resin solution is difficult to control and the synthesis is difficult, and handling such as emulsification and dispersion of the obtained resin may be difficult. Furthermore, the flowability during heating and curing is poor, and the appearance of the coating film may be significantly impaired.
[0020]
To the water-soluble vehicle made of the cation-modified epoxy resin, a pigment that reflects light in the wavelength region dispersed in a pigment dispersion resin such as an ammonium salt is added. In addition, extender pigments, rust preventive pigments, organic solvents, surfactants and the like may be added as necessary.
[0021]
In the cationic electrodeposition coating, a known block polyisocyanate is used as a crosslinking agent. This block polyisocyanate is a block agent such as methanol, ethanol, diethanolamine, oxime, and ε-caprolactam that dissociates polyisocyanates such as tolylene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate at a specific temperature, for example, 120 to 150 ° C. It is a block.
[0022]
As the vehicle of the coating material for forming the intermediate coating layer 4, alkyd and polyester melamine resin systems are preferred. Examples of monomers constituting this resin include trimethylolpropane, neopentyl glycol, phthalic anhydride, isophthalic acid, hexa Examples include hydrophthalic acid, adipic acid, and ε-caprolactone.
[0023]
The pigment is not particularly limited, but if a paint containing a pigment that reflects light in the above wavelength region is used, the heat shielding effect can be further increased.
[0024]
As the paint vehicle for forming the topcoat layer 5, alkyd and polyester melamine resin systems for solid colors and acrylic melamine resin systems for metallic colors and clears can be suitably used.
Moreover, since there is no restriction | limiting in the pigment used for solid colors and metallic colors, a free design can be expressed.
[0025]
An example of the procedure for forming the heat-shielding multilayer coating film of the present invention is as follows. The base material 1 is degreased and washed, and after chemical conversion treatment, it is immersed in an electrodeposition bath to coat the primer layer 2 (and the back primer layer 3), After washing with water, baking is performed at 120 to 150 ° C.
Next, the intermediate coating layer 4 and the top coating layer 5 are sequentially applied by spray coating. Although baking can be performed for each layer separately, it is preferable to use a two-coat one-bake method in which the topcoat layer 5 and the clear coat layer are simultaneously baked.
[0026]
Further, the number of layers may be increased or decreased as necessary, for example, a heat insulating layer is provided between the primer layer 2 and the intermediate coating layer 4 for the purpose of further improving the heat shielding property.
[0027]
The dry film thickness of the primer layer 2 and the back surface primer layer 3 is at least 10 μm, preferably 10 to 30 μm, more preferably 15 to 20 μm in order to maintain the heat shielding effect. Moreover, the dry film thickness of the intermediate coating layer 4 and the topcoat layer 5 is 20-50 micrometers, respectively, Preferably it is 30-40 micrometers.
[0028]
【Example】
Next, the present invention will be described in more detail with reference to examples and comparative examples. In addition,% in each example represents weight%.
[0029]
Example 1
On a 30 cm × 40 cm × 0.8 mm thick iron test piece subjected to degreasing and chemical conversion treatment, a heat shielding pigment-containing electrodeposition paint having the following composition was applied and baked at 150 ° C.
[0030]
The dry film thickness of the electrodeposition coating film (primer layer) was 20 μm, and the three-point average light reflectance in the region of 350 to 2500 nm was 22%. The light reflectance was measured in accordance with JIS A 5759 using a near-infrared spectrum measuring device (U-3500 self-recording spectrophotometer, WI lamp (iodine tungsten) used, manufactured by Hitachi, Ltd.).
[0031]
Heat-shielding pigment-containing electrodeposition coating composition Amino-modified epoxy resin (number average molecular weight 2200) 15.0%
Infrared reflective pigment 0.4%
(A mixture of benzimidazolone, phthalocyanine and quinacridone pigments)
Titanium white 3.3%
Extender pigment (Si-Al) 1.0%
Antirust pigment (Pb-Si) 0.3%
Additives (neutralizing agents, etc.) 0.6%
Solvent (cellosolve) 1.8%
Pure water 77.6%
[0032]
Next, Olga P-2 8101 (manufactured by Nippon Paint Co., Ltd., intermediate coating) is spray-coated on the electrodeposition coating film, and Olga P-2-1 202B (manufactured by Nippon Paint Co., Ltd., top coating) is further formed thereon. Was spray-coated and co-baked at 140 ° C.
The dry film thicknesses of the intermediate coating film and the top coating film were both 40 μm.
[0033]
The test piece on which the heat shielding multilayer coating film completed as described above was formed was set in the test box for temperature measurement shown in FIG. 2 and tested, and the results are shown in Table 1 below.
[0034]
This box comprises a main body 6 made of heat insulating foam (polystyrene foam) and a lid 7 made of the same material.
[0035]
In order to perform the temperature measurement test, first, the test piece 8 is placed on the main body 6 and fixed by the frame 7. Further, a thermocouple 9 for measuring the surface temperature is installed on the outer surface of the test piece 8, a thermocouple 10 for measuring the back surface temperature is installed on the back surface, and a thermocouple 11 for measuring the center temperature of the box is installed in the center of the main body 6. Is measured with a thermometer 12 (HR2500E, manufactured by Yokogawa Electric Corporation). Then, a 100 V, 200 W infrared lamp 13 (Toshiba Reflex Lamp RF, manufactured by Toshiba Corporation) was placed at a position 15 cm above the center of the test piece 8 and irradiated with heat rays, and each temperature after 1 hour was measured.
[0036]
Examples 2 to 4 and Comparative Examples 1 to 4
Tests were performed in the same manner as in Example 1 except that the paint used for the top coat layer, intermediate coat layer, electrodeposition layer, and back electrodeposition layer was changed, the type of temperature measurement test box was changed, and a heat insulation layer was added. Pieces were created and a temperature measurement test was performed. In addition, the said heat insulation layer used in some examples is a layer provided between the intermediate coating layer and the electrodeposition layer, The coating composition is as follows.
[0037]
Coating composition of heat insulation layer Polyester resin 29.8%
(Number average molecular weight 2500, acid value 6, OH value 100)
Melamine resin (Butylated melamine, number average molecular weight 1200) 10.0%
Epoxy resin 4.0%
(Epichlorohydrin-bisphenol type, number average molecular weight 900)
Hollow beads (made of ceramic) 1.0%
Surfactant (non-silicone) 0.2%
Solvent 45.0%
(Aromatic hydrocarbon, ester and alcohol mixtures)
[0038]
In addition, the composition of Power Top V6 (manufactured by Nippon Paint Co., Ltd.), which is an electrodeposition layer forming paint used in the comparative example, is as follows.
[0039]
Electrodeposition coating composition of comparative example Amino-modified epoxy resin (number average molecular weight 2200) 15.0%
Carbon black 0.1%
Titanium white 3.6%
Extender pigment (Si-Al) 1.0%
Antirust pigment (Pb-Si) 0.3%
Additives (neutralizing agents, etc.) 0.6%
Solvent (cellosolve) 1.8%
Pure water 77.6%
The three-point average light reflectance in a 350-2500 nm area | region of the electrodeposition coating film of the comparative example was 12.0%.
The specifications and test results of each example and comparative example are shown in Tables 1 and 2.
[0040]
As is apparent from the results of the above Examples and Comparative Examples, it has been found that the box center temperature can be sufficiently lowered without using a thermal barrier coating for the overcoat layer.
[0041]
[Table 1]

[0042]
[Table 2]

[0043]
【The invention's effect】
As described above, according to the present invention, at least the primer layer of the heat shielding multilayer coating film does not contain carbon black, and the light reflectance in accordance with JIS A 5759 in the wavelength region of 350 to 2500 nm is 20 to 90%. Because it uses the paint which is, it shows a sufficient heat shielding effect. Even if a heat shielding paint is not used for the outermost layer portion, sunlight passes through the upper coating film and reaches the primer layer, and this primer layer reflects sunlight so that a shielding effect is obtained.
[0044]
Further, since the outermost layer coating does not require the use of a heat shielding paint, it does not affect the appearance, and is therefore particularly useful for articles such as automobiles where design is an important factor.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a heat shielding multilayer coating film of the present invention.
FIG. 2 is a sectional view of a temperature measurement test box according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Base material 2 Primer layer 3 Back surface primer layer 4 Middle coating layer 5 Top coating layer 6 Main body 7 Frame 8 Test piece 9, 10, 11 Thermocouple 12 Thermometer 13 Infrared lamp

Claims (2)

In the multilayer coating film in which a primer layer, an intermediate coating layer and a top coating layer are sequentially formed on the surface of the substrate, the primer layer does not contain carbon black and conforms to JIS A 5759 in the wavelength region of 350 to 2500 nm. Ri is 20% to 90% der light reflectance, the a primer layer is electrodeposited coating, heat shielding multilayer coating, characterized in <br/> that are formed on both sides of the substrate. The heat-shielding multilayer coating film according to claim 1 , wherein the substrate is an automobile body.

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