JP4500915B1 - Photocatalytic coating for shielding heat rays - Google Patents

Abstract

【Task】
The present invention paints on the outdoor side of building glass to form a coating film that shields the heat rays and prevents the glass and the indoor temperature from rising, shortens the time for operating the cooling machine, reduces power consumption, and glass An alcohol-based photocatalytic coating that prevents thermal cracking and contamination of the resin is provided.
[Solution]
In the alcohol photocatalyst coating material of the present invention, isopropyl alcohol and ethyl diglycol are added to a solution in which a double oxide in which antimony pentoxide and zinc oxide are combined in methanol is dispersed, and then ethyl silicate, amorphous silica, methyl trioxide is added to ethanol. Alcohol-based photocatalyst containing a liquid in which alkoxysilane is dispersed and finally added with titanium oxide, forming a transparent, pencil-hardened 8H hydrolysis-resistant coating film that is cured at room temperature and shields heat rays It is a paint.
[Selection figure] None

Description

The present invention relates to an alcohol-based photocatalyst coating that forms a transparent, hard, hydrolysis-resistant coating having high thermal conductivity that cures at room temperature and transmits visible light when coated on glass but shields heat rays (near infrared rays).

  In order to prevent the temperature inside the building from rising and to reduce the amount of power consumed by shortening the operating time of the cooling machine, the roof and walls are insulated to prevent heat conduction. However, about 70% of the heat rays (radiant heat) incident on the indoors are from glass. If the heat dose incident from the glass is reduced to prevent the indoor temperature from rising, the power consumption for the cooling machine should be reduced. I can't. Insulation films and heat ray shielding paints that are applied to the indoor side of glass are sold as countermeasures, but many of them contain organic heat ray absorbers, UV absorbers, acrylic resins, etc., so heat rays that have absorbed low heat conductivity Block heat dissipation. When heat rays are stored in glass, it expands and heat cracks occur, so glass manufacturers announced that cracks could not be prevented without eliminating the cause of heat cracks, and announced the calculation formula and coefficient of heat crack strength. Encourage them to take preventive measures. In particular, if paints that prevent heat dissipation are applied to the indoor side of the glass, the amount of heat stored in the paint film and the glass becomes extremely large, and it is warned that it should not be applied to induce cracks due to thermal expansion. The actual situation is that the indoor side is painted with paint that prevents heat dissipation. Because the sash is broken when the glass expands, it should not be painted on building glass in “Japan” where earthquakes occur frequently. There is a need for a safe construction method that suppresses the temperature rise inside the building, prevents the loss and waste of cooling power, and reduces consumption.

These conventionally known inventions include the following patent documents.
Japanese Patent No. 3908252

  The present invention paints on the outdoor side of the glass and forms a transparent coating that shields the heat rays by blocking the heat rays, shortens the operating time of the cooling machine, reduces the power consumption, and It is intended to provide a photocatalyst paint that prevents thermal cracking and contamination of the film.

  The present invention is an alcohol-based photocatalyst coating that forms a transparent, highly hydrolysis-resistant heat-conductive film having a pencil hardness of 8H that cures at room temperature and shields heat rays when coated on the outdoor side of glass.

A heat ray-shielding alcohol photocatalyst coating material preferable in the composition range shown below is obtained.

Ingredient name Mixing ratio (wt%)

Ethyl silicate 0.8-2.0

Amorphous silica 0.2 ~ 2.0

Methyl trialkoxysilane 4.0-6.0

Double oxide 18.0 to 22.0 in which antimony pentoxide and zinc oxide are combined

Titanium oxide 0.2-1.0

Methanol 12.0-15.0

Ethanol 24.0-26.0

Ethyl diglycol 2.5-9.0

Isopropyl alcohol residue

When the present invention is coated on the outdoor side of the glass, the irradiated heat rays are shielded (reflected and absorbed) before entering the glass, so that the incident heat dose is reduced to less than half and the rise in the glass and indoor temperature can be suppressed. I can do it.

The thermal conductivity of the components of the coating film of the present invention is 24 to 148 times that of glass (1 W / m · K), and the heat rays absorbed by the coating film are dissipated into the atmosphere in real time. There is little rise and expansion and does not induce thermal cracking.

Thermal conductivity comparison

Material Thermal conductivity (W / m ・ k)

Antimony
24.3

Zinc oxide 117.0

Silicon 148.0

Glass 1.0

Acrylic resin 0.058

When the coating film of the present invention is irradiated with sunlight, the heat rays are shielded to suppress the rise in the indoor temperature, the operation time of the cooling machine is shortened and the power consumption is reduced, so the consumption of fossil fuel used for power generation is also It has the effect of reducing greenhouse gas emissions.

When the painted surface of the present invention is irradiated with sunlight, the active oxygen generated by the photocatalytic reaction decomposes the organic matter that is in contact with it, so that dirt is hardly attached to the coating film.

When the coating surface of the present invention is irradiated with sunlight, the coating film becomes hydrophilic, so that the attached water wets, spreads and falls with dirt.

Since the coating film formed by the present invention removes static electricity, it does not adsorb dust.

The alcohol photocatalyst paint of the present invention is prepared by mixing isopropyl alcohol and ethyl diglycol in a liquid in which a double oxide in which antimony pentoxide and zinc oxide are combined in methanol is dispersed, and then ethyl silicate, amorphous silica, methyltril in ethanol. A liquid in which alkoxysilane is dispersed is blended, and finally titanium oxide is added.

The ethyl silicate in the present invention reacts with moisture in the air and hydrolyzes to cure the coating film.

Amorphous silica increases the density of the paint and is useful for preventing the precipitation of titanium oxide.

  Methyltrialkoxysilane is useful for increasing the transparency of the coating and preventing hydrolysis of the coating.

Antimony oxide is a double oxide in which antimony pentoxide and zinc oxide are combined. It transmits visible light but absorbs heat rays to prevent transmission.

A double oxide in which antimony pentoxide is combined with zinc oxide is highly stable, unlike a substance in which antimony is doped with zinc oxide.

    The present invention will be further described below with reference to examples.

After mixing isopropyl alcohol 36.5 and ethyl diglycol 2.5 in a liquid in which a double oxide 18.0 in which antimony pentoxide and zinc oxide are bonded to methanol 12.0 (% by weight) is dispersed, ethanol 25 A liquid in which ethyl silicate 0.8, amorphous silica 0.2, and methyltrialkoxysilane 4.5 were dispersed in 0.0 was mixed, and finally titanium oxide 0.5 was added to prepare a photocatalyst coating material.

A sample was prepared by applying the alcohol-based photocatalyst paint prepared as described above to glass and curing it at room temperature for 48 hours. The hardness of the coating film was measured based on the standard of JIS K5404, resulting in a pencil hardness of 8H.

  As a result of measuring the hardness of the coating film after immersing the sample in water for 30 days (720 hours), the pencil hardness of the coating film was 8H, the hardness was not reduced by hydrolysis, and hydrolysis resistance was demonstrated. .

  As a result of measuring the sample with a spectrophotometer, the visible light transmittance was 77.7%, but the heat ray shielding rate was 55.5% (absorption 49.5%, reflection 6.0%). It was.

  When the blending amount of titanium oxide in the photocatalyst coating is less than 0.2%, a sufficient photocatalytic effect cannot be obtained, and the effect of decomposing dirt is reduced. When titanium oxide is blended in an amount of 1.5% or more, curing of the coating film is inhibited and the hardness is lowered, so that wrinkles are easily peeled off.

When 10% or more of ethyl diglycol is blended, the fluidity of the coating is improved, but it takes 30 minutes or more until the coating is dried, and the coating film is distorted, so that the transparency is lowered.

When the present invention is applied with a urethane squeegee for glass cleaning, it is possible to form a transparent and hard hydrolysis-resistant heat ray-shielding effect.

Claims (1)

0.8 to 2.0% by weight of ethyl silicate, 0.2 to 2.0% by weight of amorphous silica, 4.0 to 6.0% by weight of methyltrialkoxysilane, antimony pentoxide and zinc oxide combined. and the composite oxide from 18.0 to 22.0 wt%, titanium oxide 0.2 to 1.0 wt%, methanol 12.0 to 15.0 wt%, 24.0 to 26.0 weight ethanol %, Ethyl diglycol 2.5-9.0% by weight, and the remainder is isopropyl alcohol. Forms a transparent, highly hydrolysis-resistant, heat-resistant coating film with a pencil hardness of 8H that shields heat rays. Alcohol-based photocatalytic paint.