JP2013147571A - Heat-shielding coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-shielding coating that is capable of forming a new heat-shielding coating film to be expected to further improve heat-shielding performance (increase in solar reflectance).SOLUTION: A heat-shielding coating is obtained by dispersing spherical fine particles made of a metal oxide and rutile-type titanium oxide having a specific particle diameter into a synthetic resin and forms a heat-shielding coating film. The median size of the spherical fine particles (former) is 0.1-1.5 μm and that of the titanium oxide (latter) having the specific particle diameter is 0.5-2.0 μm. The blending ratio of the titanium oxide having the specific particle diameter to the spherical fine particles is the latter/the former =0.2 to 0.8.

Description

  The present invention relates to a thermal barrier paint. More specifically, it can be applied to the surface of buildings and road surfaces to reflect sunlight, which is the main cause of heat storage, so as to prevent the heat from entering the building and suppress the temperature rise on the road surface, so-called high solar reflection. It is invention which concerns on the heat-shielding coating material which shows a rate.

  In the specification and claims, “parts” and “%” indicating the blending units are mass units unless otherwise specified. The meaning of each technical term is as follows.

    1) “Heat insulation”: The action of blocking the inflow of heat from outside by reflecting solar radiation.

    2) “Solar reflectance”: a value measured at an incident angle of 2 ° according to JIS K5602 “How to determine solar reflectance of coating film”.

3) “Median diameter (50% value)”: Median diameter based on JIS Z8825-1 “Laser diffraction distribution curve”
In the test examples, measurement was performed using “HORIBA LA-750” (trade name, manufactured by Horiba, Ltd.).

4) “Spherical”: A sphericity of 0.7 or more (a sphericity of less than 0.7 shall be “non-spherical”). Note that “sphericity” is calculated based on the area and circumference of the particles obtained from a photograph taken with a scanning electron microscope (SEM) (sphericity) = {4π × (area) ÷ (perimeter length) ² }
(Refer to Patent Document 2, paragraph 0006).

  In recent years, as an effective preventive measure for the heat island phenomenon, which has been a problem mainly in urban areas, thermal barrier paints that can suppress the temperature rise of buildings and road surfaces have attracted attention.

  For example, although not affecting the patentability of the present invention, Patent Documents 1 and 2 can be cited.

  In Patent Document 1, “a paint containing a non-white pigment and a white pigment as essential components, wherein the rutile titanium oxide having an average particle size of 0.5 to 1.4 μm is used as the white pigment.” Claim 1) is proposed.

  Further, Patent Document 2 proposes “a water-based coating composition in which inorganic particles containing spherical metal oxide particles (for example, silica having a sphericity of 0.7 or more) are blended” (claims). Yes.

JP 2006-8874 A International Publication No. 2006/104290 Pamphlet

  In view of the above, the present invention provides a thermal barrier paint that is not described in the prior art documents and can form a new thermal barrier coating that can be expected to further improve thermal barrier performance (increase in solar reflectance). For the purpose.

  As a result of intensive development in order to solve the above-described problems, the present inventors have come up with a heat-shielding paint having the following constitution.

Metal oxide spherical particles and rutile-shaped titanium oxide having a specific particle diameter are dispersed in a synthetic resin to form a thermal barrier coating,
The median diameter of the spherical fine particles and the specific particle size titanium oxide is in the range of the former: 0.1 to 1.5 μm and the latter: 0.5 to 2.0 μm.

And, the thermal barrier paint has the composition of the coating film component,
Synthetic resin content: 15-70%,
Spherical fine particles: 20 to 60%,
Specific particle size titanium oxide: 5-35%, and
It is desirable to satisfy the requirements of spherical fine particles + specific particle size titanium oxide: 30 to 80%, and further specific particle size titanium oxide / spherical fine particles: 0.2 to 0.8.

  When the thermal barrier paint of the present invention is applied to an outer wall surface of a building, the solar reflectance is higher than that of a conventional thermal barrier paint (for example, Patent Document 2) containing “spherical fine particles made of metal oxide”. It can be expected to improve the heat shielding performance.

It is a graph which shows the relationship between the wavelength of each coating film formed with the specific particle size titanium oxide compounding paint, the spherical fine particle compounding paint and the commercial paint and the spectral reflectance. It is a spectral spectrum figure of a solar ray (sunlight).

  Hereinafter, embodiments of the thermal barrier paint of the present invention will be described.

  The thermal barrier coating according to the present invention comprises metal oxide spherical fine particles (hereinafter simply referred to as “spherical fine particles”) and rutile-shaped titanium oxide having a specific particle size dispersed in a synthetic resin. To form.

  Here, the dispersion state of the spherical fine particles in the thermal barrier coating is desirably dispersed so that the spherical fine particles do not form secondary particles (aggregated particles). When the spherical fine particles become secondary particles, the median diameter becomes relatively large, and it becomes difficult to achieve the reflectance increasing action near 1000 nm, which the spherical fine particles originally play.

  Here, as for the particle size of the spherical fine particles, the median diameter is preferably 0.1 to 1.5 μm, more preferably 0.2 to 1.0 μm, and still more preferably 0.3 to 0.8 μm. The sphericity of the spherical fine particles is preferably 0.7 or more, more preferably 0.8 or more, and even more preferably 0.9 or more. When the sphericity is large, it is easier to secure the effect of increasing the reflectance near 1000 nm.

When the median diameter and sphericity are in this range, the reflectance in the entire wavelength region (particularly, the near infrared wavelength region 700 to 1200 nm) is relatively high (see FIG. 1). That is, the near-infrared (heat ray) wavelength region includes the first peak (950 to 1050 nm) in the solar radiation spectrum distribution diagram (FIG. 2), and efficiently increases the solar radiation (heat ray) reflectance of the thermal barrier coating. FIG. 1 shows a composition of a commercially available (general purpose) acrylic resin-based paint, in which the pigment titanium oxide of the commercially available paint is replaced with an equivalent amount of titanium oxide having a specific particle diameter (TiO ₂ : median diameter 1.0 μm). It was, and spherical fine particles (SiO _2: sphericity 0.95, median diameter 0.5 [mu] m) for each paint blended together with the commercially available paint, which is the result of measuring under the same conditions.

  Examples of the metal oxide include silica, alumina, zirconia and the like, and silica having high solar reflectance is desirable.

More desirably, “silica fine particles” having a specific surface area of 30 m ² / g or less and a sphericity of 0.8 or more that are marketed under the trade name “Admafine” (registered trademark) can be suitably used. It is.

  The amount of the spherical fine particles is preferably 20 to 60%, more preferably 25 to 50% in the composition of the coating film component. By making the blending amount of the spherical fine particles 20% or more, it is easy to ensure the reflectance increasing action in the wavelength region near 1000 nm that the spherical fine particles bear. Moreover, it is easy to ensure the balance between the heat shielding properties and the physical properties of the coating film by adjusting the blending amount of the spherical fine particles to 20 to 60%.

  The specific particle size titanium oxide preferably has a median diameter of 0.5 to 2.0 μm, more preferably 0.6 to 1.5 μm, and still more preferably 0.8 to 1.2 μm. When titanium oxide with a specific particle size in this range is included, the reflectance is smaller on the short wavelength side than the specific particle size side compared with the pigment titanium oxide, but the reflection on the long wavelength side (near infrared wavelength region). The rate drop is small (see FIG. 1). That is, since the near-infrared wavelength region contains the second peak (1100 to 1250 nm) and the third peak (1450 to 1600 nm) in the solar radiation spectrum diagram (FIG. 2) by a spectrophotometer, the solar radiation ( (Heat ray) efficiently increase the reflectivity. In general, the particle size of titanium oxide (titania) used as a white pigment is set to an average particle size of about 0.3 μm or less (Patent Document 1 [0003]).

  The blending amount of the specific particle size titanium oxide is preferably 5 to 35%, more preferably 10 to 25% in the composition of the coating film component. By setting the blending amount of the specific particle size titanium oxide to 5% or more, it is easy to ensure an increase in reflectance in the near-infrared wavelength region where the specific particle size titanium oxide is responsible for reflection. Moreover, it is easy to ensure the balance of heat-shielding property and coating-film physical property by making the compounding quantity of specific particle size titanium oxide into 5-35%.

  The total amount of the spherical fine particles and the specific particle size titanium oxide is preferably 30 to 80%, more preferably 40 to 70% in the coating film component composition. By making the total amount of spherical fine particles and titanium oxide having a specific particle size 30 to 80%, it is easy to ensure a balance between the heat shielding performance and the physical properties of the coating film.

  When the blending amount of the spherical fine particles and the specific particle size titanium oxide and the total blending amount of both are small, it is difficult to obtain an effect of increasing the solar reflectance. On the other hand, if the amount is large, the addition of auxiliary materials for improving the physical properties of the coating film is limited. As a result, it becomes difficult to obtain practical physical properties of the coating film (durability, stain resistance and degree of coloring freedom).

  The mass ratio between the spherical fine particles and the specific particle size titanium oxide is preferably specific particle size titanium oxide / spherical fine particles: 0.2 to 0.8, and more preferably 0.3 to 0.7. When blended at this ratio, the first peak (large) in the near-infrared wavelength region of the spectrum distribution of sunlight (sunlight) and the second and third peaks lower than the first peak can be reflected efficiently and in a balanced manner, and the heat shielding performance is improved. Rise. Furthermore, the total amount of the two can be made relatively small, and as described above, the addition of the auxiliary material is not limited, and it is easy to obtain good coating film properties (durability, stain resistance, and coloring freedom).

  As described above, the first peak and the second and third peaks in the near-infrared wavelength region of the solar radiation spectrum are specifically assigned by the spherical fine particles and the specific particle size titanium oxide, and the solar reflection of the coating as a whole. The rate increases dramatically.

  In addition to titanium oxide having a specific particle diameter, pigment titanium oxide (median diameter of 0.3 μm or less), various other white pigments, and organic and inorganic coloring pigments may be used in combination.

  Moreover, the following can be mentioned as a white pigment and a coloring pigment combined with a pigment titanium oxide.

White pigment: zinc white, lithopone, lead white, etc.
Color pigments: Cadonium red, red bean, toluidine red, yellow lead, iron yellow, titanium yellow, fast yellow, anthraquinone yellow, benzidine yellow, chromium oxide, phthalocyanine green, bitumen, ultramarine blue, phthaloncyanine blue, and the like.

  Examples of the synthetic resin (coating resin: binder) include the following various thermoplastic / thermosetting synthetic resins.

  Acrylic resin, styrene resin, urethane resin, silicone resin, fluorine resin, epoxy resin, melamine resin, alkyd resin, vinyl chloride resin, vinyl acetate resin, polyester resin.

  These resins may be appropriately selected from various forms. For example, an emulsion system in which a synthetic resin is dispersed in water as a dispersion medium, or a solution system in which a synthetic resin is dissolved in a solvent such as water or an organic solvent can be used.

  Here, the composition of the synthetic resin (resin component: binder) in the coating film component is preferably 15 to 70%, and more preferably 30 to 50%. When the resin content is small, it is difficult to obtain the properties (durability, stain resistance, etc.) required for the coating film. When the resin content is large, the blending amount of spherical fine particles and specific titanium oxide is relatively small, and the coating film is excellent. It becomes difficult to obtain heat insulation performance.

  Alternatively, a solventless synthetic resin that does not use a solvent may be used. Thermal barrier coatings using these forms of synthetic resins become coating materials such as coatings, and after coating, they form a coating film component (coating film) by drying or reaction curing.

  The heat-shielding paint of the present invention may further include those commonly used in paints as other auxiliary materials. For example, extender pigments (calcium carbonate, kaolin clay), coating film forming sub-elements (viscosity adjusting agent, surfactant, film-forming aid, antifoaming agent, preservative, etc.) are added as appropriate.

  The desirable composition (1) of the coating film component and the more desirable composition (2) of the coating film component of the thermal barrier paint of the present invention are as follows.

Composition of coating film component (1)
Synthetic resin content: 15-70%,
Spherical fine particles: 20 to 60%,
Specific particle size titanium oxide: 5-35%,
Spherical fine particles + specific particle size titanium oxide: 30 to 80%, and
Specific particle size titanium oxide / spherical fine particles: 0.2 to 0.8.

Composition of coating film component (2)
Synthetic resin content: 30-50%
Spherical fine particles: 25 to 50%,
Specific particle size titanium oxide: 10 to 25%,
Spherical fine particles + specific particle size titanium oxide: 40 to 70%, and
Specific particle size titanium oxide / spherical fine particles: 0.3 to 0.7.

  The thermal barrier paint of the present invention having the above composition is adjusted to a suitable viscosity with water or other dispersion medium, and is applied to the outdoor wall surface of the building, roof, rooftop floor by general application means such as spraying and brushing. It is applied to the entire surface such as a surface or a predetermined site. The coating thickness at this time is 30 to 1000 μm, preferably 100 to 500 μm. If the coating thickness is too thin, it is difficult to obtain an effect of increasing the solar reflectance (heat shielding effect), and if it is too thick, no further effect of increasing the solar reflectance (heat shielding property improving effect) can be obtained. .

  The thermal barrier coating of the present invention can be made into a thermal barrier coating by cooling and solidifying a dispersion containing spherical fine particles and specific particle size titanium oxide together with other auxiliary materials in a thermoplastic resin heated and melted.

  In addition, it can be applied as a heat shield member by placing (sticking, etc.) a film or sheet (plate) formed only with a heat shield paint or via a support at the target site. It is.

  As described above, the thermal barrier paint of the present invention is suitable for outer walls and roofs of buildings, etc., but paving (asphalt, concrete, etc.) without changing the composition (auxiliary material) or as appropriate. The present invention can be applied to any part where heat shielding is required, such as a surface, a wall surface in a room, and an outer wall surface of an outdoor tank.

  Hereinafter, in order to confirm the effect | action and effect of the thermal-insulation coating material based on this invention, the Example performed with the comparative example is described. As the spectrophotometer, “Spectrophotometer UV-3600” (manufactured by Shimadzu Corporation) was used.

<Test Example A>
The paints (heat-shielding paints) having the respective compositions shown in Table 1 are prepared, and those coated on an aluminum metal plate so as to have a dry film thickness of 300 μm using each heat-shielding paint are defined in JIS K5602. The solar reflectance in a wavelength range of 300 to 2500 nm was measured.

  From Table 1 showing the results, the following can be understood.

  The solar reflectances of Examples 1 to 6 are those of Comparative Example 1 (no blending of silica fine particles and specific particle size titanium oxide), Comparative Example 2 (silica fine particles only), and Comparative Example 3 (specific particle size titanium oxide only). It can be seen that the solar reflectance is significantly increased compared to any of the above, and a significant improvement in the heat shielding property can be expected. When the mixing ratio of the specific particle size titanium oxide to the silica fine particles is in the range of 0.3 to 0.7 (Example 2-6), the total amount of the silica fine particles and the specific particle size titanium oxide is small, and a large solar reflectance is obtained. It can be said that it is easy. That is, the total amount of silica fine particles and specific particle size titanium oxide can be reduced, and it becomes easy to maintain good coating film properties (durability, stain resistance, etc.).

Claims (5)

Metal oxide spherical particles and rutile-shaped titanium oxide having a specific particle diameter are dispersed in a synthetic resin to form a thermal barrier coating,
The median diameter of the spherical fine particles and the specific particle size titanium oxide is in the range of the former: 0.1 to 1.5 μm and the latter: 0.5 to 2.0 μm. The composition of the coating film component is
Synthetic resin content: 15-70%,
Spherical fine particles: 20 to 60%,
Specific particle size titanium oxide: 5-35%, and
Spherical fine particles + specific particle size titanium oxide: 30 to 80%,
The thermal barrier coating material according to claim 1, wherein   The thermal barrier paint according to claim 2, wherein the composition of the coating film component further satisfies the requirement of specific particle size titanium oxide / spherical fine particles: 0.2 to 0.8. A thermal barrier coating material that forms a thermal barrier coating film in which spherical fine particles made of metal oxide and titanium oxide having a specific particle size in the rutile form are dispersed in a synthetic resin,
The median diameter of the spherical fine particles and the specific particle size titanium oxide is in the range of the former: 0.2 to 1.0 μm, the latter: 0.6 to 1.5 μm,
The composition of the coating film component is
Synthetic resin content: 30-50%
Spherical fine particles: 25 to 50%,
Specific particle size titanium oxide: 10 to 25%,
Spherical fine particles + specific particle size titanium oxide: 40 to 70%, and
Specific particle size titanium oxide / spherical fine particles: 0.3 to 0.7,
Thermal insulation paint characterized by satisfying the requirements of The thermal barrier coating material according to any one of claims 1 to 4, wherein the spherical fine particles are silica fine particles having a sphericity of 0.8 or more.

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