JP2005061042A - Solar heat intercepting pavement body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pavement body having excellent solar heat intercepting property with a high temperature reducing effect in spite of having a dark surface color tone. <P>SOLUTION: A first paint film layer containing a white pigment of 15% or more in solar radiation reflectance specified in JIS A 5759 is disposed on the surface of the pavement body, and a second paint film layer containing a dark color pigment absorbing light in a visible wavelength range and reflecting and/or transmitting light in an infrared wavelength range is disposed in an upper layer on the first paint film layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a coating technique for suppressing a temperature rise on the surface of a road pavement or the like due to solar radiation energy.

  Artificial structures such as asphalt pavement typically absorb sunlight's solar energy and cause internal heat storage, resulting in a high surface temperature and a cause of heat island phenomenon in urban areas. Therefore, measures to improve the urban thermal environment including the heat island phenomenon in urban areas are desired. As one of the countermeasures, a method of providing a solar heat-shielding coating film on the surface of the pavement has been studied.

  As a general technique for providing a solar heat-shielding coating film, conventionally, the solar reflectance specified in JIS A 5759 of the surface coating film is adjusted to a wavelength as high as possible, and the visible part of solar energy and red Means have been mainly taken to reflect on the surface of the coating without absorbing the outside, energize the constituent components of the coating by absorption, and prevent changes to thermal energy.

  Since these mainly use white pigments, particularly in road pavements, there is a problem that the color tone is too bright and is not suitable for traffic use. That is, in a road pavement, white marking lines are often provided on the surface of the pavement, so that there is a problem that it is difficult to distinguish the marking lines from the road pavement surface when the color tone is too bright.

In recent years, dark-colored heat-shielding paints such as black have also been proposed (Patent Document 1).
The present applicants have proposed an invention for a solar heat-blocking pavement in which the surface layer of the pavement contains hollow fine particles and / or a pigment that absorbs in the visible wavelength range and reflects in the infrared wavelength range (patent) Reference 2). Although this technique exhibits an effective temperature reduction effect particularly for road pavements, further improvements in technical effect and economy are desired.
JP 2000-129172 A International Publication Number WO 03/046286

    An object of the present invention is to provide a pavement that has a surface color tone suitable for a road pavement and the like and suppresses a temperature rise due to solar radiation energy, that is, has a coating film with high solar heat blocking properties. .

  As a result of intensive studies to achieve the above object, the present applicants have found that a solar heat blocking effect can be obtained more effectively by assigning functions to a plurality of coating layers, and have reached the present invention.

  That is, the present invention includes a first coating layer containing a white pigment having a solar reflectance of 15% or more as defined in JIS A 5759 on the surface of the pavement, and the first coating layer. A solar heat-blocking pavement comprising a second coating layer containing a dark pigment that absorbs light in the visible wavelength range and reflects and / or transmits light in the infrared wavelength range as an upper layer. .

  In the present invention, a coating layer containing a white pigment having a high solar reflectance is disposed in the lower layer, and the upper layer absorbs light in the visible wavelength region and reflects and / or transmits light in the infrared wavelength region. By providing a coating film layer containing a dark pigment, the function of reflecting sunlight in both layers is shown, as shown in FIG. On the other hand, all of the conventional solar heat-blocking pavements described above are intended to reflect sunlight by the coating layer on the surface (FIG. 1), and have the concept of sharing the function among a plurality of coating layers. What you have is not known.

  In the present invention, a pavement refers to an object that is desired to suppress a temperature rise due to solar heat, and particularly an asphalt pavement, a concrete pavement, and an interlock that are considered to be one of the causes of a heat island phenomenon in an urban area. Examples include road pavements such as block pavements, pedestrian passage surfaces such as poolsides and parks, and pavements such as tennis courts.

  In the present invention, it is indispensable to dispose the first coating layer and the second coating layer as essential coating layers on the surfaces of these paving bodies. Usually, the first coating layer is used as a layer constituting an undercoat layer, and the second coating layer is used as a layer constituting an overcoat layer. When the undercoat layer is composed of two or more layers, the first coating layer is preferably applied as the uppermost layer of the undercoat layer. The pigment to be contained in the first coating layer can be used without particular limitation as long as it is a white pigment having a solar reflectance of 15% or more in a wavelength range of 350 to 2100 nm as defined in JIS A 5759. A white pigment having a ratio in the range of 40 to 95% is preferable, and typical examples thereof include titanium dioxide, zinc white, lithopone, and titanium yellow. The content of these pigments is preferably 10 to 80% by weight of the first coating layer and more preferably 15 to 40% by weight. The thickness of the first coating layer is preferably 50 to 500 μm. By arranging such a first coating layer, it is possible to reflect light in the infrared wavelength region that has passed through the topcoat layer, and as a result, the amount of solar radiation energy that reaches the surface of the pavement that covers the undercoat layer is reduced. It can reduce more effectively, and it becomes possible to suppress more effectively the temperature rise of the circumference | surroundings brought about by a pavement body storing and heat-dissipating.

The second coating layer described above is arranged as at least one of the top coating layers applied to the upper layer from the first coating layer. It is essential for the second coating layer to contain a dark pigment that absorbs light in the visible wavelength region and reflects and / or transmits light in the infrared wavelength region. Here, the dark color pigment refers to a pigment having a lightness (L ^* value) of 40 or less, typically black. In particular there is solar reflectance of 15% or more in the wavelength range of 350~2100nm defined in JIS A 5759, and ^{L *} value in CIE1976L ^* a ^* b ^* color space is 30 or less, more preferably ^{L *} value A dark pigment that is 24 or less is preferred. Typical examples of pigments satisfying such conditions include the general formula:

[However, X in the above formula is N = N or CONH, n is 1 or 2, R ₁ is a hydrogen atom or a nitro group, R ₂ is a halogen atom or a methoxy group, and the A ring is A benzene ring or a naphthalene ring, and when n = 1, R ₃ is a phenyl group which may have a halogen atom, a methyl group, a nitro group or a methoxy group, or a naphthyl group which has no substituent, and n When R = 2, R ₃ is a biphenylene group which may have a methoxy group. And azo pigments (crystal size: 0.3 to 10 μm) (Patent Document 3). It is possible to know whether the pigment can be used for the second coating layer of the present invention by confirming whether or not the above-mentioned conditions are satisfied for a commercially available dark color pigment. Examples of commercially available pigments that satisfy the above conditions include azomethiazo black pigments (manufactured by Dainichi Seika Kogyo Co., Ltd.) having a trade name of Chromofine Black A-1103.
Japanese Patent Publication No. 4-26348

  The content of these pigments is preferably 0.01 to 10% by weight, more preferably 0.1 to 3% by weight of the second coating layer. The thickness of the second coating layer is preferably 50 to 500 μm. By providing such a second coating layer, the coating layer is a dark color system such as black, and reflects and / or transmits thermal energy due to light in the infrared wavelength region contributing to temperature rise. As a result, it is possible to more effectively reduce the amount of solar radiation energy that reaches the surface of the pavement together with the first coating layer, and to increase the surrounding temperature caused by heat storage and heat dissipation of the pavement. It becomes possible to suppress with higher economic efficiency.

The second coating layer preferably contains an extender pigment in addition to the dark pigment. As the extender pigment, a white extender pigment in which any one of the following coating film concealment rate, coating film brightness L ^* value and coating film infrared transmittance satisfies the following conditions is preferably used.

(A) An extender having a coating film concealment rate of 20 to 90% as defined in JIS K 5400 measured for the coating layer. Here, the method for measuring the coating film concealment rate is as follows. A peroxide compound and a curing agent are blended in a paint composed of 75 parts by weight of a transparent resin (for example, methacrylic resin) and 25 parts by weight of an extender pigment, and this material is applied to a hidden pay rate test paper defined in JIS K 5400. A coating film is formed by applying to a thickness of 1000 μm. Next, the hidden pay rate is calculated from the diffuse reflectance measured by the method of JIS K 5574-1961 for the white ground and black ground coating films of the hidden pay rate test paper.
Hidden pay rate = 45 degree 0 degree diffuse reflectance of black ground paint film / 45 degree 0 degree diffuse reflectance of white ground paint film

(B) CIE 1976 L ^* a ^* b ^* measured for the coating film layer An extender having a coating film brightness L ^* value of 50 or less in the color space. Here, the method for measuring the coating film brightness L ^* value is as follows. 75 parts by weight of a transparent resin (for example, methacrylic resin), 25 parts by weight of extender pigment, and 0.125 by weight of a pigment (for example, methiazo black) that absorbs light in the visible wavelength range and reflects and / or transmits light in the infrared wavelength range A coating film is formed by applying the coating material consisting of a part to the above-described concealment rate test paper so as to have a wet coating film thickness of 1000 μm. Next, the L ^* value is measured with a color computer for the white ground coating film.

(C) An extender having a coating film infrared transmittance of 10% or more measured for the coating film layer. Here, the method for measuring the coating film infrared transmittance is as follows. 75 parts by weight of a transparent resin (for example, methacrylic resin), 25 parts by weight of extender pigment, 0.125 by weight of a pigment (for example, methiazo black) that absorbs light in the visible wavelength range and reflects and / or transmits light in the infrared wavelength range A coating film is formed by applying a coating composed of a part on a PET film so as to have a wet coating thickness of 500 μm. Next, about this coating film, the infrared transmittance in wavelength 1.4-3.0 micrometers is measured using a Fourier-transform infrared spectrometer.

  The extender pigments that satisfy at least one of the conditions (a) to (c) have weak coloring power and have a color tone that is nearly transparent in the resin liquid. Therefore, the extender layer contains these extender pigments. Thus, even if the content of the dark color heat reflective pigment is reduced, the dark color surface tone can be maintained.

  Specific examples of extender pigments that satisfy the above conditions include calcium carbonate (including surface-treated calcium carbonate called calcigros), calcium silicate, and the like.

  The content of these extender pigments in the second coating layer is preferably 10 to 80% by weight, more preferably 10 to 40% by weight, based on the total weight of the coating film. If the content of these extender pigments is too small, it is difficult to obtain a coating strength that can sufficiently withstand traffic service, and if it is too much, the binding strength of the binder resin may be insufficient.

  The first coating layer (or any of the undercoat layers) and / or the second coating layer (or any of the top coating layers) in the present invention preferably contains hollow fine particles as necessary. . By containing hollow fine particles, the undercoat layer and / or the overcoat layer can improve the performance of reflecting light in the infrared wavelength region, which contributes to increasing the effect of reducing the ambient temperature of the pavement.

The hollow fine particles used in the present invention are preferably inorganic hollow fine particles, particularly transparent or translucent ceramic hollow fine particles, and among them, ceramic hollow fine particles having a strength of 40 kgf / cm ² or more are preferred. Examples of such ceramic compositions include zirconia-titania composites, silicon boride ceramics, shirasu balloons, glass balloons and the like. The particle diameter is preferably 5 to 150 μm. The inside of the hollow may be air, a gas other than air, or a vacuum, but a vacuum (where vacuum means a state where the atmospheric pressure is lower than the atmospheric pressure) is more effective from the viewpoint of heat insulation. It is.

  In some cases, the first coating layer and / or the second coating layer in the present invention may contain other extender pigments as necessary. Examples of these include synthetic quartz spherical silica, spherical alumina, and phosphate glass powder. These extender pigments can exhibit functions corresponding to each of them such as improving the strength of the coating film and increasing the thermal conductivity, and the content thereof is usually 5 to 40 wt. %.

  As binder resin which comprises each coating-film layer, the appropriate binder resin conventionally apply | coated on the pavement body can be used. Although it is not particularly limited as long as it satisfies the physical property requirements such as strength required for the coating film to be applied to the surface of the pavement and can secure the workability when applying the paint, it is usually for paint with transparency. Resin is used. The types of these resins include vinyl ester resins, unsaturated polyester (meth) acrylate resins, epoxy (meth) acrylate resins, urethane (meth) acrylate resins, methyl (meth) acrylate resins, polyester resins, silicon-modified polyester resins, Examples thereof include silicon-modified acrylic resin, alkyd resin, vinyl chloride resin, and fluororesin.

  Particularly preferable as the pavement of the present invention is an asphalt pavement using asphalt mixture containing asphalt and aggregate as essential components for the surface layer. In the present invention, the coating layer is formed so as to follow the surface shape of the pavement. In the case of an asphalt pavement, a coating layer is formed according to the uneven shape of the surface, and this surface shape serves to further enhance the properties of the coating. Examples of the asphalt mixture for the surface material of the asphalt pavement include a fine particle size asphalt mixture, a dense particle size gap asphalt mixture, an open particle size asphalt mixture, etc., and examples of functionally expressed asphalt pavement include light color pavement, There are colored pavement, anti-freezing pavement, drainage pavement, water permeable pavement, semi-flexible pavement, crushed stone mastic pavement, etc.

  In particular, when the surface layer is formed using a drainage pavement mixture that is a porous asphalt mixture having a high porosity, the coating layer may be formed so as to maintain the voids and the function of the surface layer. preferable. That is, it is preferable to form the coating layer so as not to block the voids, and in this way, the drainage function is further improved.

Reference example:
(1) Measurement of coating pigment concealment rate of extender pigment A paint having 25 parts by weight of the extender pigment shown in Table 1 and 75 parts by weight of a methacrylic resin mixed with a peroxide compound and a curing agent was prepared. It coat | covers on the hidden pay rate test paper to prescribe | regulate, and forms a coating film with a wet coating-film thickness of 1000 micrometers. And the hidden pay rate was measured by the method of JIS K 5574-1961 about the coating film on the white ground and the black ground of the hidden pay rate test paper. The results are shown in Table 1.

(2) Measurement of coating film lightness L ^* value of extender pigment A paint comprising 0.125 parts by weight of methiazo black, 25 parts by weight of various extender pigments, and 75 parts by weight of methacrylic resin was applied to a test paper with a concealment rate and wet coating. A coating film having a thickness of 1000 μm was formed, and the coating film on the white ground of the test paper with the hidden pay rate was measured with a color computer. The results are shown in Table 2.

(3) Measurement of coating film infrared transmittance of extender pigment The coating material used for the measurement of L ^* value was applied on a PET film to form a coating film having a wet coating thickness of 500 μm. The infrared transmittance at ˜3.0 μm was measured by a Fourier transform infrared spectrometer (manufactured by Thermo Nicolet Japan Co., Ltd.). The results are shown in Table 3.

Example:
1. Preparation of paint A paint was prepared according to the formulation shown in the following table. A numerical value shows a weight ratio.

(Note) Methiazo Black is an azomethiazo black pigment manufactured by Dainichi Seika Kogyo Co., Ltd. The defoamer is manufactured by Shin-Etsu Chemical Co., Ltd. Rutile titanium white (general purpose) has a primary average particle size of about 0.25 μm.

2. Formation and evaluation of coating layer (1)
In order to confirm the temperature reduction effect by the coating film, the following experiment was conducted. First, a specimen having a size of 50 mm × 300 mm × 300 mm made of a dense particle size asphalt mixture was prepared. A heat insulating material was placed around each specimen so that it was not affected by heat other than solar radiation. After a thermocouple of a thermometer was attached to the center of the surface of the specimen, each paint was sprayed on the surface of the specimen to form an undercoat film thickness of 300 μm and an overcoat film thickness of 300 μm to form a paint film. . For comparison, a specimen having a size of 50 mm × 300 mm × 300 mm (hereinafter referred to as “standard specimen”) made of a drainage pavement mixture was prepared, and no paint was sprayed on the specimen. . And the difference of the surface temperature of a standard specimen and each specimen was made into the temperature reduction value, and the maximum value of the temperature reduction value in a measurement day was made into the temperature reduction maximum value.

  This experiment was conducted on June 1, 2003. The weather on this day was a maximum temperature of 26.8 ° C, a minimum temperature of 21.7 ° C, a maximum wind speed of 5m / sec, a rainfall of 0mm, and a sunshine duration of 8 hours. It was 6 minutes. Table 5 shows the measurement results of the properties of the coating film (asphalt pavement board).

Comparison between A-1 and C-1:
From the measurement results in Table 5, it can be seen that the coating film C-1 has a greater effect of reducing the temperature by 5.7 ° C. than the coating film A-1. Moreover, about solar reflectance, it turns out that the direction of the coating film C-1 is 20.5% larger than the coating film A-1. That is, the topcoat 1 has a two-layer structure comprising an undercoat layer containing a pigment having a high solar reflectance and a topcoat layer containing a pigment that absorbs light in the visible wavelength range and reflects and / or transmits light in the infrared wavelength range. Compared with a coating layer composed of only a layer, a coating layer having a high solar reflectance and a large temperature reduction effect can be obtained.

Comparison between B-1 and B-2:
From the measurement results in Table 5, it can be seen that the coating film B-2 has a greater 1.2 ° C. temperature reduction effect than the coating film B-1. That is, by adding spherical alumina to the undercoat layer, it is possible to obtain a coating layer having a large temperature reduction effect as compared with a coating layer made of an undercoat layer not containing spherical alumina.

Comparison between B-1 and C-1:
From the measurement results in Table 5, it can be seen that the coating film C-1 has a greater 1.5 ° C. temperature reduction effect than the coating film B-1. Moreover, about solar radiation reflectance, it turns out that the direction of the coating film C-1 is 4.1% larger than the coating film B-1. That is, by blending a hollow ceramic balun into the top coat layer, it is possible to obtain a paint layer having a high solar reflectance and a large temperature-reducing effect as compared with a paint layer composed of a top coat layer not blended with a hollow ceramic balun. it can.

3. Formation and evaluation of coating layer (2)
An experiment similar to the above was conducted with the tin plate regarded as a paving body. The results are shown in Table 6.

  From the measurement results in Table 6, it can be seen that the same effect as in the case of the asphalt pavement plate was also exhibited in the tin plate.

4). Comparison test by pavement The case of using a dense particle size asphalt mixture and a drainage pavement mixture as an asphalt mixture for the surface layer was used as an example, and the difference in the heat shielding effect when the type of pavement was changed was compared.
(1) Temperature measurement One specimen having a size of 50 mm × 300 mm × 300 mm made of a dense particle size asphalt mixture and a drainage pavement mixture was prepared. Table 7 shows the composition of each mixture.

  A heat insulating material was placed around each specimen so that it was not affected by heat other than solar radiation. After a thermocouple of the thermometer is attached to the center of the surface of the specimen, each paint is sprayed on the surface of each specimen to form a coating film of 300 μm for the undercoat and 300 μm for the topcoat. did. The composition of the paint is shown in Table 4.

For comparison, a specimen (hereinafter referred to as “standard specimen”) having a size of 50 mm × 300 mm × 300 mm made of a drainage pavement mixture was separately prepared, and no paint was sprayed on the specimen. It was. And the difference of the surface temperature of a standard specimen and each specimen was made into the temperature reduction value, and the maximum value of the temperature reduction value in a measurement day was made into the temperature reduction maximum value.
Each specimen was placed in a sunny area outdoors, and the surface temperature of the specimen every hour was measured. The measurement results are shown in Table 8. As for the weather on the measurement day, the maximum temperature was 27.4 ° C., the minimum temperature was 21.9 ° C., the maximum wind speed was 4 m / sec, the rainfall was 0 mm, and the sunshine duration was 8 hours and 12 minutes.

(2) Comparison of measurement results From the measurement results shown in Table 8, for coating film B-1, the temperature of the specimen made of the drainage pavement mixture is 1.6 ° C lower than that of the specimen made of the dense particle size asphalt mixture. The effect was great. Moreover, also about the coating film C-1, the test piece which consists of a drainage pavement mixture had a 1.3 degreeC temperature reduction effect larger than the test piece which consists of a dense particle size asphalt mixture. From this, it can be said that the specimen made of the drainage pavement mixture has a greater temperature reduction effect due to the coating layer than the specimen made of the dense particle size asphalt mixture. In addition, the pavement cross-sectional example at the time of using a dense particle size asphalt mixture and a drainage pavement mixture as a surface layer mixture is shown in FIG. 3, and the state of the coating layer of the pavement surface layer portion is shown in FIG.

  According to the present invention, it is possible to maintain a dark color tone while using a small amount of dark-colored heat-reflective pigment by sharing the solar heat blocking function among a plurality of coating films, and to obtain a large temperature reduction effect with good economic efficiency. Is possible.

The conceptual diagram which shows reflection of the sunlight in the conventional solar thermal interruption paving. The conceptual diagram which shows reflection of the sunlight in the solar-heat-shielding pavement of this invention. Sectional drawing which shows an example of the pavement at the time of using a dense particle size asphalt mixture and a drainage pavement mixture as a surface layer mixture. The schematic sectional drawing which shows the state of the coating-film layer of the pavement surface layer part in FIG.

Explanation of symbols

1 Pavement 2 Coating layer 3 Coating layer (top coating)
4 Coating layer (undercoat)
5 Surface layer 6 Base layer (Coarse grained asphalt mixture)
7 Upper layer roadbed 8 Lower layer roadbed 9 Coating layer

Claims (11)

  On the surface of the pavement, a first coating layer containing a white pigment having a solar reflectance of 15% or more as defined in JIS A 5759, and a visible wavelength region above the first coating layer A solar heat-blocking pavement comprising a second coating layer containing a dark pigment that absorbs the light of and absorbs and / or transmits light in the infrared wavelength region.   The solar heat-blocking pavement according to claim 1, wherein the white pigment is titanium dioxide or zinc white.   The solar heat-shielding pavement according to claim 1 or 2, wherein the white pigment is present in the first coating layer in an amount of 10 to 80% by weight.   The solar heat-shielding pavement according to any one of claims 1 to 3, wherein the dark pigment is present in the second coating layer in an amount of 0.01 to 10% by weight.   The solar heat-shielding pavement according to any one of claims 1 to 4, wherein the second coating layer further contains an extender pigment. The extender is (a) an extender having a coating film concealment ratio of 0.2 to 0.9, (b) an extender having a coating film brightness L ^* value of 50 or less, or (c) an infrared transmittance of the coat is 10 The solar heat-blocking pavement according to claim 5, wherein the pavement is an extender pigment of at least%.   The solar heat-blocking pavement according to claim 5 or 6, wherein the extender pigment is calcium carbonate and / or aluminum silicate.   The solar heat-blocking pavement according to any one of claims 5 to 7, wherein the extender pigment is present in the second coating layer in an amount of 10 to 80% by weight.   The solar thermal barrier pavement according to any one of claims 1 to 8, wherein the first coating layer and / or the second coating layer further contains hollow fine particles.   The solar heat-blocking pavement according to any one of claims 1 to 9, wherein a surface layer of the pavement is composed of a drainage pavement mixture.   The solar heat-blocking pavement according to any one of claims 1 to 9, wherein the surface layer of the pavement comprises a dense particle size asphalt mixture.

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