JP2015000910A - Coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition capable of forming a transparent coating film with both high heat-shielding properties and high strength on a surface of a transparent substrate.SOLUTION: The coating composition is used to form a transparent coating film on a surface of a transparent substrate and contains an infrared-absorbing inorganic compound, a binder resin, and a curing agent. The content of the infrared-absorbing inorganic compound is 5.0-20.0 mass% based on the total amount of the infrared-absorbing inorganic compound, the binder resin, and the curing agent. The hydroxyl value of the binder resin is 10-200 mgKOH/g. The curing agent preferably has two or more isocyanate groups.

Description

  The present invention relates to a coating composition. More specifically, the present invention relates to a coating composition used for forming a transparent coating film having both high heat shielding properties and strength on the surface of a transparent substrate.

  Conventionally, from the viewpoint of reducing environmental burden and cost, buildings and structures such as buildings and houses are required to save energy. As a measure for saving energy in buildings and structures, it is conceivable to increase the heat shielding property of the window glass and prevent the temperature rise in the room due to sunlight transmitted through the window glass.

Therefore, in order to enhance the heat shielding properties of the window glass of buildings and structures, heat shielding glasses such as heat insulating glass and heat shielding laminated glass have been developed. Moreover, in order to achieve the same objective, the thermal insulation film stuck on the existing window glass is also developed.
However, heat-shielding glass, particularly heat-shielding laminated glass, is expensive and has only been popularized in some newly built properties. In addition, the heat-shielding film has problems such as when the surface of the window glass is an uneven surface or when the heat-shielding film and the glass surface are not completely adhered to the screen glass, and the construction is difficult. Maintenance such as cleaning is not easy, and there is a problem in durability.

On the other hand, a method of applying a paint capable of forming a transparent coating film having a heat shielding property to the window glass is known as a technique that can more easily impart the heat shielding property to the window glass.
Examples of the paint capable of forming a transparent coating film having heat shielding properties include, for example, a transparent group containing tin-containing indium oxide (ITO) as an infrared absorbing inorganic compound, an acrylic resin having a hydroxyl group, and a tetrafunctional silicon compound. Infrared thermal barrier coatings for materials are known (see Patent Document 1).

  In addition, an ultraviolet / near-infrared shielding paint containing an acrylic resin, an acrylic siloxane cross-linking reactive polymer, an organic ultraviolet absorber, and an inorganic near-infrared absorber (see Patent Document 2), polycarbonate There is also known an ultraviolet / near-infrared blocking water-based paint containing a polyurethane aqueous emulsion resin as a main component and further containing an ultraviolet absorber and an inorganic near-infrared absorber (see Patent Document 3).

JP 2002-309157 A JP 2007-106826 A JP 2013-87228 A

Since these paints contain an infrared absorbing inorganic compound, they can exhibit heat shielding properties. Therefore, in order to improve the heat shielding properties of the coating film formed by these coating materials, it is conceivable to increase the mass concentration of the infrared absorbing inorganic compound in the coating material.
However, when the mass concentration of the infrared absorbing inorganic compound in the solid content of the coating composition is increased, the mass concentration of the resin solid content in the coating film is decreased, so that the coating film strength is reduced and the durability of the coating film is also reduced. It tends to end up.

  By the way, while increasing the mass concentration of resin solids in the coating film to ensure the coating film strength, the coating film is formed by increasing the film thickness of the coating film for the purpose of improving the thermal barrier properties of the coating film. It is also conceivable to improve the mass of the infrared absorbing inorganic compound per unit area. However, an increase in the film thickness of the coating film may cause problems such as a decrease in visibility through a glass on which a transparent coating film has been formed and sagging during coating. Therefore, it is better not to increase the film thickness of the coating film as much as possible in the technical field related to a transparent coating film having heat shielding properties.

  Thus, it is possible to form a coating film having high strength after increasing the mass concentration of the infrared absorbing inorganic compound in the solid content of the coating composition so that the heat shielding property can be exhibited with a sufficiently thin film thickness. The present condition is that the coating composition is not obtained. In the first place, Patent Documents 1 to 3 disclose a coating composition that forms a heat-shielding coating film, but no consideration is given to forming a coating film having both high heat-shielding properties and strength. . Patent Document 1 describes that a specific tetrafunctional silicon compound and / or a condensate thereof reacts with a hydroxyl group contained in an acrylic resin and contributes to curing of the coating film. However, the mass concentration of the infrared absorbing inorganic compound in the solid content of the coating composition exemplified in Patent Document 1 is as low as 0.06 to 2.37 mass% (calculated value). As described above, the coating composition exemplified in Patent Document 1 forms a coating film having both high heat shielding properties and strength after increasing the mass concentration of the infrared absorbing inorganic compound in the solid content of the coating composition. It is not a thing.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a coating composition capable of forming a transparent coating film having both high heat shielding properties and strength on the surface of a transparent substrate. To do.

  The present invention is a coating composition used for forming a transparent coating film on the surface of a transparent substrate, comprising an infrared absorbing inorganic compound, a binder resin, and a curing agent, the infrared absorbing inorganic The content of the infrared absorbing inorganic compound in the total amount of the compound, the binder resin and the curing agent is 5.0 to 20.0% by mass, and the hydroxyl value of the binder resin is 10 to 200 mgKOH / g. A coating composition

  The curing agent is preferably a compound having two or more isocyanate groups.

  The infrared absorbing inorganic compound preferably contains at least one selected from the group consisting of tin-containing indium oxide (ITO), antimony-containing tin oxide (ATO), and aluminum-added zinc oxide (AZO).

  Moreover, this invention relates to the coating-film formation method which forms a coating film on the surface of a transparent base material using the said coating composition.

  Moreover, this invention relates to the transparent coating film formed on the surface of a transparent base material by the said coating-film formation method.

  Moreover, this invention relates to the transparent member which has a transparent base material and the said transparent coating film formed on the surface of the said transparent base material.

  ADVANTAGE OF THE INVENTION According to this invention, the coating composition which can form the transparent coating film which made high heat-shielding property and intensity | strength compatible on the surface of a transparent base material can be provided.

  Hereinafter, embodiments of the present invention will be described. In addition, this invention is not limited to the following embodiment.

<Coating composition>
First, the coating composition of this embodiment is demonstrated.
The coating composition of this embodiment is a coating composition used for forming a transparent coating film on the surface of a transparent substrate, and includes an infrared absorbing inorganic compound, a binder resin, and a curing agent. .

  The transparent base material is a concept including not only a completely colorless and transparent base material but also a colored and transparent base material in which the inside can be seen through. A transparent base material is not specifically limited, The base material comprised by organic substances, such as inorganic substances, such as glass, and plastics, is mentioned. Examples of the transparent substrate include buildings and building windows, automobile window glass, sunroofs, optical fibers, PET (polyethylene terephthalate) bottles, packaging films, sun visors, and glasses.

  A primer may be applied to the transparent substrate in advance, and in that case, the coating composition of the present embodiment can be applied as a clear coating. It is also possible to apply the coating composition of the present embodiment to a transparent substrate as a primer and to apply a clear coating thereon. Furthermore, the coating composition of the present embodiment may be used as a primer and a clear coating, and a coating film may be provided on the lower layer and / or the upper layer as desired. The transparent coating film in this embodiment means a coating film having a spectral transmittance of 70% or more at a wavelength of 550 nm.

  The coating composition of this embodiment contains an infrared absorbing inorganic compound. The infrared absorbing inorganic compound is an inorganic compound that favorably absorbs near infrared rays (wavelength: 700 to 2500 nm) among infrared rays. The infrared-absorbing inorganic compound absorbs near infrared rays satisfactorily, whereas the absorption of visible light (wavelength: 360 to 700 nm) is preferably low. Since the infrared absorbing inorganic compound absorbs near infrared rays well and absorbs as little visible light as possible, a coating film having a high heat absorption property is formed on the surface of the substrate by the coating composition. Visibility through is increased. In the present embodiment, the highly heat-absorbing coating film (coating film having high heat-shielding property) refers to a film having an infrared (wavelength: 1500 nm) spectral transmittance of less than 20%.

Examples of the infrared absorbing inorganic compound in the present embodiment include antimony-containing tin oxide (ATO), tin-containing indium oxide (ITO), aluminum-added zinc oxide (AZO), titanium oxide, zinc oxide, cerium oxide, ruthenium oxide, and the like. .
The coating composition of this embodiment is selected from the group consisting of antimony-containing tin oxide (ATO), tin-containing indium oxide (ITO), and aluminum-added zinc oxide (AZO), which absorbs near infrared rays well, as the infrared absorbing inorganic compound. It is preferable to contain at least one selected from the above.

  The content of the infrared-absorbing inorganic compound in the total amount of the infrared-absorbing inorganic compound, the binder resin and the curing agent of the coating composition of the present embodiment (hereinafter sometimes simply referred to as “the content of the infrared-absorbing inorganic compound”), Is 5.0-20.0 mass%. The content of the infrared absorbing inorganic compound is determined by the following formula (1). In the following formula (1), A is the mass content of the infrared absorbing inorganic compound in the coating composition, B is the mass content of the binder resin in the coating composition, and C is the mass of the curing agent in the coating composition. Content.

  In the coating composition of this embodiment, the coating film formed has high heat-shielding property because the content rate of an infrared rays absorption inorganic compound is 5.0 mass% or more. When the content of the infrared absorbing inorganic compound in the coating composition is less than 5.0% by mass, the heat shielding property of the formed coating film is lowered, and when it is 20.0% by mass, the strength of the formed coating film is low. Therefore, the durability of the coating film is also lowered. The content of the infrared absorbing inorganic compound is more preferably 6.5 to 15.4% by mass.

  The average particle diameter of the primary particles of the infrared absorbing inorganic compound is preferably 0.01 μm to 0.2 μm. When the average particle size of the primary particles of the infrared absorbing inorganic compound is less than 0.01 μm, it is difficult to obtain a coating composition in which the particles of the infrared absorbing inorganic compound are aggregated and the particles of the infrared absorbing inorganic compound are dispersed. When the average particle diameter of the primary particles of the infrared absorbing inorganic compound exceeds 0.2 μm, the formed coating film may have low transparency to visible light, that is, transparency. The average particle diameter of primary particles of the infrared absorbing inorganic compound is a numerical value measured by an electron microscope method and obtained from an average value and a standard deviation for 100 particles.

  As specific products of the infrared absorbing inorganic compound in the present embodiment, TDL-S (ATO dispersion) manufactured by Mitsubishi Materials Electronics Chemical Co., Ltd., X-100 series (ITO dispersion) manufactured by Sumitomo Metal Mining Co., Ltd., Examples thereof include T-1 (ITO dispersion liquid) manufactured by Mitsubishi Materials Electronics Chemical Co., Ltd., Nanotech ITO (ITO dispersion liquid) manufactured by CI Kasei Co., Ltd., 23-K (AZO powder) manufactured by Hakusui Chemical Industries, and the like.

The coating composition of this embodiment contains a binder resin. The binder resin in the present embodiment is not particularly limited as long as it has a hydroxyl group, and examples thereof include acrylic polyol, polyester polyol, and polyether polyol.
As the binder resin, it is preferable to use an acrylic polyol because of transparency of visible light (wavelength: 360 to 700 nm).

  The hydroxyl value of the binder resin in the present embodiment is preferably 10 to 200 mgKOH / g. As mentioned above, the coating composition of this embodiment contains many infrared absorption inorganic compounds. In the prior art, if the mass concentration of the infrared absorbing inorganic compound in the total solid content of the coating composition is increased, the mass concentration of the resin solid content in the coating film is decreased, so that the coating film strength is reduced and the durability of the coating film is also improved. It tends to decrease. Therefore, in the present invention, attention is paid to the fact that when a binder resin having a high hydroxyl value is used, the crosslinking reaction between the binder resin and a curing agent described later proceeds frequently. In the coating composition of the present embodiment, a dense coating film having a large number of cross-linked portions is formed because a large amount of cross-linking reaction between the binder resin and the curing agent proceeds. That is, the coating composition of this embodiment is formed even when the mass concentration of the infrared absorbing inorganic compound in the total solid content of the coating composition is high and the mass concentration of the resin solid content in the coating film is small. High coating strength. Thus, the coating composition of this embodiment can form a transparent coating film compatible with heat shielding properties.

If the hydroxyl value of the binder resin is less than 10 mg KOH / g, the curability becomes insufficient and the strength of the resulting coating film is lowered. When the strength of the coating film decreases, the durability of the coating film also decreases. When the hydroxyl value of binder resin exceeds 200 mgKOH / g, there exists a possibility that the water resistance and durability of the coating film obtained may fall. The hydroxyl value of the binder resin is more preferably 30 to 170 mgKOH / g.
The hydroxyl value of the binder resin can be determined by a neutralization titration method using a potassium hydroxide aqueous solution described in JIS K 0070.

  The weight average molecular weight of the binder resin is preferably 1,000 to 50,000. When the weight average molecular weight of the binder resin is less than 1,000, the strength of the resulting coating film tends to be insufficient, and when it is more than 50,000, the handleability of the coating composition tends to be lowered. The weight average molecular weight can be measured and determined by gel permeation chromatography (GPC) using polystyrene standard sample standards.

  As a specific product of the binder resin in the present embodiment, Jonocry 507 (manufactured by BASF, hydroxyl value: 140 mgKOH / g, weight average molecular weight: 12,500), Dianal LR-2673 (manufactured by Mitsubishi Rayon Co., Ltd., hydroxyl group) Value: 170 mg KOH / g, weight average molecular weight: 13,000), A-801 (manufactured by DIC Corporation, hydroxyl value: 48.6 mg KOH / g, weight average molecular weight: 40,000), WAU-880 (manufactured by DIC Corporation) Hydroxyl value: 20 mg KOH / g, weight average molecular weight: 44,000), and the like.

  The content of the binder resin in the total solid content of the coating composition of the present embodiment is preferably 50.0 to 99.0% by mass. When the content of the binder resin in the total solid content of the coating composition is less than 50.0% by mass, the strength of the formed coating film tends to be low. In addition, when the content of the binder resin in the total solid content of the coating composition is larger than 99.0% by mass, the content of the infrared absorbing inorganic compound in the formed coating film is reduced, so that high heat shielding properties are obtained. When trying to obtain, it is necessary to increase the film thickness.

  The coating composition of this embodiment contains a curing agent. As the curing agent, an organic crosslinking agent having a plurality of functional groups capable of reacting with the hydroxyl group of the binder resin in the molecule can be used. Examples of the organic crosslinking agent include a melamine resin, a phenol resin, a compound having a plurality of epoxy groups, a compound having two or more isocyanate groups, a compound having a plurality of oxazoline groups, and a compound having a plurality of carbodiimide groups. These may be used alone or in combination of two or more. As the curing agent, it is preferable to use a compound having two or more isocyanate groups because it reacts well with a binder resin having a hydroxyl group and the formed coating film has high strength. Examples of the compound having two or more isocyanate groups include aliphatic diisocyanates such as hexamethylene diisocyanate, hydrogenated diphenyl diisocyanate, and isophorone diisocyanate; 2,4- / 2,6-tolylene diisocyanate, 4,4′-diphenylmethane. Aromatic diisocyanates such as diisocyanate and m- / p-xylene diisocyanate can be mentioned. Specific products of compounds having two or more isocyanate groups include TLA-100, TSA-100, TPA-100 (above, aliphatic diisocyanate) manufactured by Asahi Kasei Co., Ltd., Bernock D-750 from DIC Corporation, DN-950, DN-980 (above, aromatic diisocyanate) and the like can be mentioned.

  The curing agent is preferably added in an amount such that the equivalent ratio of the functional group of the curing agent capable of reacting with a hydroxyl group to the hydroxyl group of the binder resin is 0.8 to 1.2. If the value of the equivalent ratio of the functional group of the curing agent capable of reacting with a hydroxyl group to the hydroxyl group of the binder resin is outside the above range, the crosslinking reaction in the coating does not proceed sufficiently and the coating strength becomes low. The durability of the coating film tends to be low. In particular, when a compound having an isocyanate group is used as a curing agent, the value of the ratio of the isocyanate group of the curing agent to the hydroxyl group of the binder resin is expressed as “value of NCO / OH equivalent ratio”. The value of the NCO / OH equivalent ratio here refers to the molar ratio of the isocyanate (NCO) group in the polyisocyanate compound to the hydroxy (OH) group in the polyol compound.

  The coating composition of this embodiment may contain a curing catalyst in order to accelerate the curing of the coating film. Examples of the curing catalyst include organic tin compounds such as dibutyltin laurate, dibutyltin octiate, dibutyltin acetate, and dioctyltin laurate; inorganic acids such as hydrochloric acid, nitric acid, phosphoric acid, and boric acid; acetic acid, formic acid, maleic acid, Organic acids such as benzoic acid; Phosphate esters such as monomethyl phosphate; Organic titanium compounds such as tetrabutyl titanate and tetrabutoxy titanate; γ-aminopropyltrimethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxy Silane coupling agents such as silane and γ-ureidopropyltriethoxysilane; Organoaluminum compounds such as tris (acetylacetonate) aluminum and tris (ethylacetoacetate) aluminum; tetrabutylzirconate, butoxytris (acetate) Organozirconium such as Ruasetonato) zirconium; ethylenediamine, diethylenetriamine, amines such as diethanolamine; sodium hydroxide, and inorganic bases such as potassium hydroxide.

  The content of the curing catalyst in the total solid content of the coating composition of the present embodiment is preferably 0.01 to 30% by mass. When the content of the curing catalyst in the total solid content of the coating composition is less than 0.01% by mass, the effect of accelerating the curing is small, and when it is more than 30% by mass, the strength of the formed coating film tends to be low. is there.

  The coating composition of this embodiment preferably contains an ultraviolet absorber. An ultraviolet absorber is a compound that absorbs particularly near ultraviolet rays (wavelength: 200 to 360 nm) of ultraviolet rays. When the coating composition contains an ultraviolet absorber, the formed coating film can well shield ultraviolet rays. Although an ultraviolet absorber is not specifically limited, In order to prevent the fall of the intensity | strength of the coating film formed, it is preferable to use an organic ultraviolet absorber. Examples of the organic ultraviolet absorber include methyl salicylate, pt-butylphenyl-salicylate, p-octylphenyl-salicylate (hereinafter referred to as salicylic acid derivative), 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4. -N-octoxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone (above, benzophenone series), 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3'- t-butyl-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-amylphenyl) benzotriazole (above, benzotriazole), 3-phenyl-7- (4'-methyl-5'-n-butoxybenzotriazolyl-2-) coumarin ( Marine-based), mention may be made of 2'-ethylhexyl 2-cyano-3,3-diphenylacrylate and the like. These can be used 1 type or in mixture of 2 or more types.

  As specific products of the ultraviolet absorber in the present embodiment, Zarol (manufactured by Dow Chemical Co., Ltd., phenyl salicylate), Seasorb 100 (manufactured by Shiraishi Calcium Co., Ltd., 2.4-hydroxybenzophenone), Sumisorb 200 (Sumitomo Chemical Co., Ltd.) And 2- (2′hydroxy-5′methylphenyl) benzotriazole) manufactured by the company.

  The content of the ultraviolet absorber in the total solid content of the coating composition of the present embodiment is preferably 1 to 20% by mass. If the content of the ultraviolet absorber in the total solid content of the coating composition is less than 1% by mass, the effect of ultraviolet absorption of the formed coating film tends to decrease, and if it exceeds 20% by mass, the coating film The strength of the steel tends to decrease.

  It is preferable that the coating composition of this embodiment contains a solvent. The solvent is not particularly limited as long as it can dissolve or disperse the infrared absorbing inorganic compound, the binder resin, the curing agent, the curing catalyst, and the ultraviolet absorber. Examples of the solvent include alcohols such as methanol, ethanol, n-propanol, i-propanol, n-butanol, and cyclohexanol; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; ethers such as methyl cellosolve and ethyl cellosolve; Examples include esters such as butyl acetate and methyl cellosolve acetate; hexane, cyclohexane, toluene, xylene and the like.

  It is preferable that content of the solvent in the coating composition of this embodiment is 5-50 mass%. When the content of the solvent in the coating composition is less than 5% by mass, the viscosity of the coating composition becomes high, the workability of the coating composition tends to be lowered, for example, the workability of coating is lowered, and a smooth coating film is not formed. . When the content of the solvent in the coating composition is more than 50% by mass, the viscosity of the coating composition becomes low, and the handleability tends to be lowered, such as sagging of the coating film during coating.

  In addition to the components described above, the coating composition of the present embodiment may contain a leveling agent, a surfactant, a silane coupling agent, an antifoaming agent, a colorant, an antioxidant, and the like as necessary. it can.

  The coating composition of this embodiment is prepared by mixing and stirring a hardening agent in the liquid which mixed and stirring components other than a hardening | curing agent among the components mentioned above. The mixing and stirring of the components contained in the coating composition is not particularly limited, and can be performed using, for example, a high speed stirrer, a ball mill, a sand mill, a paint shaker, a three roll mill or the like.

<Method for forming coating film>
Then, the coating-film formation method of this embodiment is demonstrated.
The coating film formation method of this embodiment is a method of forming a coating film on the surface of a transparent substrate using the above-mentioned coating composition. The coating film formation method of this embodiment includes the application | coating process which apply | coats a coating composition to a transparent base material.

  The coating method in the coating process is not particularly limited, and examples thereof include brush coating method, roller method, spray method, sponge coating method, bar coating method, curtain coating method (flow coating method), spin coating method, doctor blade method and the like. Can be mentioned. As a coating method in the coating step, a spray method, a sponge coating method, a brush coating method, a roller method, and a curtain coating method and a spin coating method are preferable when painting on a line such as a factory when painting on an existing window glass.

  After the coating step, the coating film can be formed by natural drying or heat treatment as necessary. Drying can be performed by leaving or heating at 20 to 100 ° C. for 10 minutes to 5 hours.

<Transparent coating>
Then, the transparent coating film of this embodiment is demonstrated.
The coating film of this embodiment is a coating film formed on the surface of a transparent substrate by the above-mentioned coating film formation method.

  It does not specifically limit as a dry film thickness of a coating film, It is 2-50 micrometers, Preferably it is 2 micrometers or more and less than 7 micrometers. A coating film having a dry film thickness of less than 2 μm tends to be difficult to form. When the dry film thickness of a coating film is thicker than 50 micrometers, it exists in the tendency for the visibility through a transparent base material to fall.

  Since the coating film of this embodiment is formed using the above-mentioned coating composition, it is possible to achieve both high heat shielding properties and strength.

<Transparent material>
Then, the transparent member of this embodiment is demonstrated.
The transparent member of this embodiment has a transparent base material and the above-mentioned transparent coating film formed on the surface of a transparent base material.

  The transparent coating film may be formed on both surfaces of the transparent substrate, or may be formed on one surface. When a coating film is formed on one side of a window glass that has already been installed in a building or building, it is preferable to form a coating film on the indoor side rather than the outdoor side of the window because the construction is simple. .

  Next, the present invention will be described in more detail based on examples, but the present invention is not limited thereto. Unless otherwise specified, “part” and “%” are all based on mass.

(Preparation of coating compositions of Example 1 and Comparative Example)
2.0 parts by mass of acrylic resin (1) as a binder resin, 1.7 parts by mass of an ATO dispersion as an infrared absorbing inorganic compound, 0.1 parts by mass of dibutyltin laurate as a curing catalyst, and ultraviolet rays In an aqueous solution obtained by mixing and stirring 0.5% by mass of TINUVIN 477 (manufactured by BASF Japan Ltd., hydroxyphenyltriazine) as an absorbent and 5.0 parts by mass of butyl acetate as a solvent. Then, 2.7 parts by mass of TPA-100 as a curing agent was added, mixed and stirred to obtain a coating composition of Example 1.

(Preparation of coating compositions of Examples 2 to 13 and Comparative Examples 1 and 2)
The coating compositions of Examples 2 to 13 and Comparative Examples 1 and 2 were prepared in the same procedure as the coating composition of Example 1, except that the composition of the raw materials of the coating composition was changed as shown in Table 1. . The unit of numerical values in Table 1 is “part by mass” unless otherwise indicated. However, there is no unit for “value of NCO / OH equivalent ratio” in Table 1.

[Binder resin]
Acrylic resin (1): Dianal LR-2675 (manufactured by Mitsubishi Rayon Co., Ltd., acrylic polyol, weight average molecular weight: 13,000, solid content: 61% by mass, hydroxyl value: 170 mgKOH / g)
Acrylic resin (2): Joncryl 507 (manufactured by BASF, acrylic polyol, weight average molecular weight: 12,500, solid content: 80% by mass, hydroxyl value: 140 mgKOH / g)
Acrylic resin (3): A-801 (manufactured by DIC Corporation, acrylic polyol, weight average molecular weight: 40,000, solid content: 50 mass%, hydroxyl value: 50 mgKOH / g)
Acrylic resin (4): WAU-880 (manufactured by DIC Corporation, acrylic polyol, weight average molecular weight: 44,000, solid content: 50 mass%, hydroxyl value: 20 mgKOH / g)

[Infrared absorbing inorganic compound dispersion]
Antimony-containing tin oxide (ATO) dispersion (Mitsubishi Materials Electronics Chemical Co., Ltd., pigment solid content: 40% by mass, dispersion medium: cyclohexanone, average particle diameter of primary particles: 0.02 nm)
Tin-containing indium oxide (ITO) dispersion (Mitsubishi Materials Electronics Chemical Co., Ltd., pigment solid content: 20% by mass, dispersion medium: isopropyl alcohol, average particle diameter of primary particles: 0.02 nm)
In addition, the content of the infrared absorbing inorganic compound (ATO or ITO) in the total amount of the infrared absorbing inorganic compound (ATO or ITO), the binder resin and the curing agent of the coating composition is expressed as “content ratio of the infrared absorbing inorganic compound”. 1.

[Curing agent]
TPA-100 (Asahi Kasei Corporation, hexamethylene diisocyanate, isocyanate group (NCO) content: 23.25% by mass)
[Ultraviolet absorber]
TINUVIN 477 (manufactured by BASF Japan Ltd., hydroxyphenyltriazine)

(Preparation of glass test piece)
Each of the coating compositions of Examples and Comparative Examples was applied to one side of a glass piece (50 mm × 50 mm × 2 mm) with a spin coater and dried at 25 ° C., thereby forming a glass having a 5 μm thick coating film. A specimen was obtained.

(Evaluation of infrared transparency (heat insulation))
The spectral transmittance of infrared rays (wavelength: 1500 nm) of the glass test pieces of Examples and Comparative Examples was measured. A spectrophotometer (UV-3600 manufactured by Shimadzu Corporation) was used for the measurement. An infrared transmittance of less than 30% was accepted. The results are shown in Table 1.

(Evaluation of visible light transmission)
The spectral transmittance of visible light (wavelength: 550 nm) of the glass test pieces of Examples and Comparative Examples was measured. A spectrophotometer (UV-3600 manufactured by Shimadzu Corporation) was used for the measurement. Visible light transmittance of 70% or more was accepted. The results are shown in Table 1.

(Evaluation of film adhesion)
The glass test pieces of Examples and Comparative Examples were cut by 25 squares with a 1 mm square using a cutter knife. The transparent pressure-sensitive adhesive tape described in JIS K 5600-5 and -6 was applied to the glass test plate, and then peeled off. The area of the peeled coating film in the 25th square of the test plate was visually measured. A film having a peeled area of 0% was regarded as acceptable. The results are shown in Table 1.

(Evaluation of durability of coating film)
The glass test pieces of Examples and Comparative Examples were dipped in boiling water for 3 hours, then removed from the hot water and wiped off moisture. Then, 25 square notches were cut into a glass test piece with a 1 mm square by a cutter knife. The transparent pressure-sensitive adhesive tape described in JIS K 5600-5 and -6 was applied to the glass test plate, and then peeled off. The area of the peeled coating film in the 25th square of the test plate was visually measured. A film having a peeled area of 0% was regarded as acceptable. The results are shown in Table 1.

  As is clear from Table 1, the coating compositions of Examples 1 to 13 in which the content of the infrared absorbing inorganic compound in the coating composition is in the range of 5.0 to 20.0% by mass are those of the infrared absorbing inorganic compound. Compared to the coating compositions of Comparative Examples 1 and 2 whose content is outside the range of 5.0 to 20.0 mass%, the formed coating film is excellent in heat shielding properties and visible light transmittance. Moreover, the coating composition of Examples 1-13 is excellent in the adhesiveness and durability of the coating film formed. From such facts, it was shown that the coating composition of the present invention can form a transparent coating film having both high heat shielding properties and strength on the surface of the transparent substrate.

Claims (6)

A coating composition used for forming a transparent coating film on the surface of a transparent substrate,
Including an infrared absorbing inorganic compound, a binder resin, and a curing agent,
In the total amount of the infrared absorbing inorganic compound, the binder resin and the curing agent, the content of the infrared absorbing inorganic compound is 5.0 to 20.0% by mass,
The coating composition whose hydroxyl value of the said binder resin is 10-200 mgKOH / g.   The coating composition according to claim 1, wherein the curing agent is a compound having two or more isocyanate groups.   The said infrared rays absorption inorganic compound contains at least 1 sort (s) selected from the group which consists of tin containing indium oxide (ITO), antimony containing tin oxide (ATO), and aluminum addition zinc oxide (AZO). Paint composition.   The coating-film formation method which forms a coating film on the surface of a transparent base material using the coating composition in any one of Claim 1 to 3.   The transparent coating film formed in the surface of a transparent base material by the coating-film formation method of Claim 4. A transparent substrate;
A transparent member comprising: the transparent coating film according to claim 5 formed on a surface of the transparent substrate.