JP4092383B2 - How to renovate building exterior - Google Patents

Description

  The present invention relates to a method for refurbishing a building outer wall.

  2. Description of the Related Art In recent years, buildings, apartment houses, detached houses, and the like have been actively used to save energy by reducing heat and cooling costs by increasing heat insulation and airtightness. In general, in buildings that have not been designed for thermal insulation, indoor heat escapes from parts such as roofs, floors, windows, walls, etc. during heating in winter, and outdoor heat enters from these parts during cooling in summer. It is said that about one third of such heat loss is caused by the wall surface. For this reason, to achieve energy savings in buildings, it is essential to increase the heat insulation of the outer wall that separates the room from the outside, and many proposals have been made to increase the heat insulation by combining heat insulating materials with the base material that constitutes the wall surface. Has been.

  On the other hand, various paints are applied and formed on the outer walls of buildings such as buildings, apartment houses, and detached houses for the purpose of improving aesthetics. Of these, organic paints that use organic resins as binders have a high degree of freedom in compounding design and can impart various hues and design properties. Is also used for general purposes. Organic paints are also used on the outer walls with improved heat insulation as described above. However, if the coating film of a general organic paint is exposed to the outdoors for a long period of time, it will deteriorate and contaminate due to the influence of sunlight, rain, dust, etc., so it needs to be repainted in about 10 years. Will arise.

However, there are some problems in repainting the organic paint film formed on the outdoor surface of the heat insulating wall.
The first is a problem of heat load on the coating film. If the heat insulating property of the building outer wall is improved as described above, the heat escape area by direct sunlight is eliminated on the outdoor side surface. For this reason, the coating film formed on the outdoor-side surface of the outer wall is directly affected by it, and the temperature is very likely to rise. Such a temperature rise may induce abnormalities such as swelling and peeling of the coating film.
Second is the problem of moisture. In general, when the coating surface is exposed directly to the outside air in organic coatings, moisture due to rain or the like is likely to be absorbed from the coating surface with the progress of deterioration, and the moisture stays in the coating or substrate. It becomes easy to do. In some cases, moisture is taken in from the back surface of the substrate. If the coating surface in such a state is renovated with normal paint, moisture is trapped inside the coating, and with the evaporation of the moisture, abnormalities such as coating swelling are likely to occur. appear. In particular, when the outer wall has a heat insulating property, the temperature rise of the coating film becomes large, so that swelling due to evaporation of moisture tends to occur.

  As described above, if an old paint film of an organic paint formed on the outdoor surface of the heat insulating wall is to be refurbished, it may swell and peel over time after construction. For this reason, usually, a method of applying the renovation paint after removing the old paint film by a method of physically cleansing the paint film or using a paint film remover is employed. However, the operation of removing the old coating film requires a great deal of labor and time, and is disadvantageous in terms of construction costs. In addition, when it is difficult to completely remove the old coating film, it is necessary to carefully perform the base preparation process, which causes a problem that the coating process becomes complicated.

  Patent Document 1 describes a method of applying a water-based elastic paint after applying a sealer as a method for refurbishing an old paint film. However, even if this method is applied to an old paint film of an organic paint formed on the outdoor surface of the heat insulating wall, it is difficult to prevent the occurrence of blistering and peeling with time.

JP-A-6-306305

  This invention is made | formed in view of such a subject, and it aims at providing the remodeling method suitable for the old coating film of the organic type coating formed in the outdoor side surface of a heat insulation wall.

  As a result of intensive studies to solve such problems, the present inventors have laminated a coating film having infrared reflectivity and water vapor permeability and having specific performance in elongation and tensile product. As a result, it was found that swelling and peeling of the coating film can be sufficiently prevented, and the present invention has been completed.

That is, the present invention has the following characteristics.
1. A method for refurbishing a building outer wall by applying and laminating at least one type of refurbishing paint to an old paint film surface formed on the outdoor side of the building outer wall,
(1) The outer wall is a heat insulating wall having a thermal conductivity of 5.0 W / (m ² · K) or less, and (2) the coating film formed by a paint having an organic resin as a binder. (3) The laminated coating film by the refurbishing paint is a coating film containing a crosslinking reaction type organic resin as a binder,
Of the renovation paints, at least one includes an infrared reflective pigment,
The reconstituted paint has a pigment volume concentration of 60 to 90% (excluding 60%),
The laminated coating film has infrared reflectivity and water vapor permeability, an elongation at 20 ° C. of 2 to 120%, and a tensile product ratio according to the following formula of 0.3 or more. How to renovate the building exterior. <Formula> “Ratio of tensile product” = “Tensile product at 60 ° C.” / “Tensile product at 20 ° C.”
2. The crosslinking reaction type organic resin is at least one selected from the group consisting of vinyl acetate resin, vinyl chloride resin, epoxy resin, acrylic resin, urethane resin, acrylic silicon resin, and fluororesin. Renovation method of building exterior wall as described in.
3. The infrared reflective pigment is made of aluminum flake, titanium oxide, barium sulfate, zinc oxide, iron oxide, magnesium oxide, alumina, antimony oxide, zirconium oxide, yttrium oxide, indium oxide, silica, magnesium silicate, and calcium carbonate. 1. at least one selected from the group Or 2. Renovation method of building exterior wall as described in.

  The present invention is suitable for refurbishing an old coating film of an organic paint formed on the outdoor surface of a heat insulating wall. According to the present invention, it is possible to sufficiently suppress the occurrence of blistering and peeling of a coating film after refurbishment over a long period of time.

The present invention relates to a method of refurbishing an old paint film formed on the outdoor side of a building outer wall.
First, the outer wall which is the subject of the present invention is a heat insulating wall having a thermal conductivity of 5.0 W / (m ² · K) or less. Such a heat insulating wall is indispensable for high thermal insulation and high airtightness of buildings. However, in a part where sunlight directly shines, the coating film formed on the outdoor surface is large. It will give a heat load. In particular, the present invention includes an outer wall having a high heat insulating performance, i.e. heat transmission coefficient is 1.0W / ^(m 2 · K) or less, more applicable to 0.50W / ^(m 2 · K) or less is heat-insulating wall In this case, a remarkable effect can be exhibited.

Such a heat insulating wall is made of one or more members. As a member constituting the heat insulating wall, there are a case where only a base material is used and a case where a base material and a heat insulating material are combined. For example, lightweight mortar, lightweight concrete, calcium silicate board, ALC board, siding board, gypsum board Substrates such as slate plate, concrete, mortar; fiber insulation such as glass wool, rock wool and cellulose fiber; insulation exemplified by foamed plastic insulation such as polyethylene foam, polystyrene foam and polyurethane foam, etc. Is mentioned. Among these, the heat insulating wall in the present invention usually contains at least one member having a thermal conductivity of 0.5 W / (m · K) or less.
The present invention is particularly effective in the case where the heat insulating wall is a base material having a low heat transmissivity, or at least when the heat insulating wall is constituted by a composite of the base material and the heat insulating material as described above.

The heat transmissivity in the present invention is a calculated value based on Appendix 4 “Calculation method of heat transmissibility” in “Finished wooden house construction common specification (with commentary)” supervised by the Housing Finance Corporation, and is obtained by the following procedure. Value.
(1) From Equation 1, the thermal resistance is calculated from the thermal conductivity and thickness of each member constituting the outer wall.
Thermal resistance = thickness / thermal conductivity (Equation 1)
(2) The thermal flow resistance is calculated from the thermal resistance of each member and the thermal resistance of the air (heat transfer resistance) according to Equation (2).
Thermal through-flow resistance = thermal resistance of indoor air + total thermal resistance of each member + thermal resistance of outdoor air (Equation 2)
(However, the thermal resistance of the indoor side air 0.11m ² · K / W, the thermal resistance of the outdoor side air to 0.04m ² · K / W)
(3) The thermal transmissivity is calculated from the thermal transmissivity by Equation 3.
Thermal flow rate = 1 / Heat flow resistance (Equation 3)

The old paint film surface in the present invention has a paint film formed by a paint using an organic resin as a binder (hereinafter also referred to as “organic paint”).
Examples of the organic paint include various paints containing an organic resin. Specifically, for example, JIS K5654 “acrylic resin enamel”, JASS18 M-207 “non-aqueous dispersion type acrylic resin enamel”, JIS K5656 “polyurethane resin paint for building”, JASS18 M-404 “acrylic silicone resin paint”, JIS K5658 “Fluorine resin paint for construction”, JIS K5660 “Glossy synthetic resin emulsion paint”, JIS K5663 “Synthetic resin emulsion paint”, JIS K5667 “Multicolored paint”, JIS K5668 “Synthetic resin emulsion paint”, JIS A6909 "Building finish coating material" exterior thin coating material E, flexible exterior thin coating material E, waterproof exterior thin coating material E, exterior thick coating material E, multilayer coating material E, waterproof multilayer coating material E, multilayer coating material RE , Waterproof multilayer coating material RE, multilayer coating material RS, waterproof multilayer coating material RE, etc. I can get lost.

The organic resin in the organic paint may be either a thermoplastic resin or a thermosetting resin. For example, acrylic resin, vinyl chloride resin, vinyl acetate resin, polyurethane resin, acrylic silicon resin, fluorine resin, epoxy resin. , Polyester resin, melamine resin, alkyd resin and the like. The present invention can provide advantageous effects particularly when the organic resin is a thermoplastic resin.
The content of the organic resin in the organic paint is not particularly limited, but is usually 5% by weight or more, preferably 20% by weight or more in the solid content of the organic paint.

  The thickness of the coating film formed by the organic paint is usually about 0.02 to 10 mm, although it depends on the form of the paint. In the present invention, even when the coating film has a thickness of 1 mm or more, it is possible to prevent swelling and peeling of the coating film after refurbishment. As a paint for forming such a thick coating film, for example, an exterior thick coating material E of JIS A6909 “Finishing finish coating material” can be cited.

  The old coating surface in the present invention may be a single-layer coating film or a multi-layer coating film as long as it has such an organic coating film. A great effect can be obtained when the paint film is present on the outermost surface of the old paint film.

  In this invention, a coating film is formed by apply | coating and laminating the coating material for renovation with respect to the above-mentioned old coating film surface. The laminated coating film formed here is composed of at least one type of refurbishment paint, and when two or more types are used as the refurbishment paint, it means a laminate of all the renovation paints.

  In the present invention, it is necessary that the laminated coating film by the renovation paint has infrared reflectivity and water vapor permeability. In the present invention, since the laminated coating film has such a performance, the temperature rise of the coating film is suppressed, and moisture in the old coating film or the base material is diffused to the outside of the coating film. Occurrence and peeling can be suppressed.

The infrared reflectivity of the laminated coating film is indicated by the infrared reflectivity obtained by measuring the spectral reflectivity with respect to light having a wavelength of 800 to 2100 nm with a spectrophotometer and calculating the average value (the fine powder of barium sulfate). (Relative value when the spectral reflectance of the hardened white plate is 100%). In the present invention, the infrared reflectance of the laminated coating film is desirably 20% or more (preferably 40% or more, more preferably 50% or more).
In the infrared reflectance measurement, an aluminum plate was coated with a black paint (containing 100 parts by volume of acrylic resin and 6 parts by volume of carbon black) so that the dry film thickness was 60 μm. Use wood.

The water vapor permeability of the laminated coating film is 20 g / m ² · 24 h or more (preferably 30 g) as measured by the method of “water vapor permeability” of JIS K5400-1990 “General Test Method for Paints” 8.17. / M ² · 24h or more). The upper limit of the water vapor transmission rate is not particularly limited, but if the water vapor transmission rate is too high, the water barrier property tends to be insufficient and water may enter the old coating film. The upper limit of the water vapor permeability is usually 500 g / m ² · 24 h or less, preferably 200 g / m ² · 24 h or less.

Furthermore, the laminated coating film by the renovation paint has an elongation at 20 ° C. (hereinafter also simply referred to as “elongation”) of 2 to 120% (preferably more than 50% and not more than 120%, more preferably more than 50%. %) And the ratio of the tensile product according to the following formula 1 is 0.3 or more (preferably 0.4 or more).
<Formula 1> “Ratio of tensile product” = “Tensile product at 60 ° C.” / “Tensile product at 20 ° C.”

In the present invention, the multilayer coating film has infrared reflectivity and water vapor permeability, and further has an appropriate elongation, and the temperature dependence of the tensile product is small. It is possible to reliably prevent the occurrence of peeling. Moreover, since the temperature rise of the coating film surface is suppressed by the infrared reflectivity of the laminated coating film, even when the elongation rate is set to be high according to the type or state of the old coating film, the occurrence of blistering is prevented. be able to. However, when the elongation rate is too larger than the above range, the coating film may be swollen or peeled off. If the elongation is too small, the coating film may be cracked.
The upper limit of the tensile product ratio is not particularly limited, but is usually less than 1. When the ratio of the tensile product is smaller than 0.3, swelling and peeling are likely to occur.

The ratio of elongation and tensile product in the present invention is a test piece punched into a dumbbell shape No. 2 specified in JIS K6251 4.1 (cured for 14 days at a temperature of 20 ° C. and a humidity of 65% after forming the coating film. At a value obtained by attaching a tensile tester specified in JIS A6021 6.3.1a) so that the grip is 60 mm and pulling the specimen at a tensile speed of 10 mm / min until the specimen breaks. is there.
The elongation percentage is calculated by the following formula 2, and the tensile product is calculated by the following formula 3.
<Formula 2> “Elongation rate (%)” = (“Elongation at break (mm)” / 60) × 100
<Formula 3> “Tensile product (N / mm)” = “Tensile strength (N / mm ² )” × “Elongation at break (mm)”
However,
“Tensile strength (N / mm ² )” = “Maximum tensile force (N)” / “Cross sectional area of test piece (mm ² )”
“Elongation at break (mm)” = “Distance between grips at break (mm)” − 60

  The laminated coating film in the present invention can be obtained by applying and laminating at least one type of refurbishment paint, but preferably composed of one type of renovation paint or two types of renovation paint. It is. Although it is possible to use three or more kinds of renovation paints, it is disadvantageous in that the painting work becomes complicated.

  In the present invention, it is necessary that at least one type of paint for refurbishment has a crosslinking reaction type organic resin as a binder. By using such a crosslinking reaction type organic resin, it becomes possible to obtain a coating film having the above-mentioned various characteristics. In addition, the crosslinking reaction type organic resin in the present invention is a general term for organic resins that undergo a crosslinking reaction after the coating film formation process or after the coating film formation.

The cross-linking reaction type organic resin may be either one that causes a cross-linking reaction by the organic resin itself or one that causes a cross-linking reaction by a cross-linking agent mixed separately. When using a crosslinking agent, the mixing amount is usually 0.05 to 50 parts by weight (preferably 0.08 to 15 parts by weight, more preferably 0.1 to 10 parts by weight) with respect to 100 parts by weight of the solid content of the organic resin. Part) grade.
Crosslinking reactivity in the crosslinkable organic resin is, for example, carboxyl group and carbodiimide group, carboxyl group and epoxy group, carboxyl group and aziridine group, carboxyl group and oxazoline group, hydroxyl group and isocyanate group, carbonyl group and hydrazino group, epoxy group. And a hydrazino group, an epoxy group, an amino group, and a reactive functional group such as an alkoxysilyl group. These combinations can be used alone or in combination of two or more.

The resin skeleton of the crosslinking reaction type organic resin is not particularly limited. For example, vinyl acetate resin, vinyl chloride resin, epoxy resin, acrylic resin, urethane resin, acrylic silicon resin, fluorine resin, or a composite system of these is used. can do.
Examples of the form of the crosslinking reaction type organic resin include water-soluble resins, water-dispersible resins, non-water-dispersed resins, solvent-soluble resins, and solvent-free resins. Among these, a water dispersible resin is suitable in the present invention.

  The glass transition temperature (Tg) of the crosslinking reaction type organic resin is desirably -80 to 80 ° C (preferably -50 to 50 ° C). When Tg is too low, the coating film tends to be swollen. When Tg is too high, the displacement of the old coating film cannot be followed, and there is a possibility that the coating film will crack. The Tg mentioned here is a value determined by the Fox calculation formula from the type of monomer constituting the cross-linking reaction type organic resin and its constituent ratio.

At least one of the refurbishing paints forming the laminated coating film uses a paint having an infrared reflective pigment. The infrared reflective pigments, like A Rumi bromide flakes, titanium oxide, barium sulfate, zinc oxide, iron oxide, magnesium oxide, alumina, antimony oxide, zirconium oxide, yttrium oxide, indium oxide, silica, magnesium silicate, carbonate calcium It is done. Among these, at least one selected from aluminum flakes, titanium oxide, zinc oxide, iron oxide, magnesium oxide, calcium carbonate, barium sulfate, and alumina is preferable.

In the paint for refurbishment, an infrared transmitting pigment can be used in combination with the infrared reflecting pigment. By using such pigments in combination, it is possible to express various colors without impairing the infrared reflection performance of the coating film. Examples of pigments having infrared transparency include perylene pigments, azo pigments, yellow lead, petals, vermilion, titanium red, cadmium red, quinacridone red, isoindolinone, benzimidazolone, phthalocyanine green, phthalocyanine blue, cobalt blue, and indus. One or more selected from ren blue, ultramarine blue and bitumen are preferred.
In the present invention, a remarkable effect can be exhibited even in hues other than white by appropriately selecting the pigment as described above.

  In the paint for refurbishment, as long as the effects of the present invention are not impaired, components that can be used in ordinary paints can be included. Examples of such components include dyes, aggregates, fibers, thickeners, film-forming aids, leveling agents, wetting agents, plasticizers, antifreezing agents, pH adjusting agents, preservatives, antifungal agents, and antifungal agents. Examples include algal agents, antibacterial agents, dispersants, antifoaming agents, ultraviolet absorbers, antioxidants, catalysts, and crosslinking agents.

In the present invention, it is particularly desirable to use a paint having a crosslinking reaction type organic resin as a binder as the first refurbishing paint (a paint in contact with the old paint film surface). In addition, this 1st renovation coating material normally does not contain an inorganic binder (Colloidal metal oxide, water-soluble alkali metal silicate, cement, etc.).
As the crosslinking reaction type organic resin in the first renovation paint, an epoxy group-hydrazino group crosslinking reaction type organic resin is particularly suitable. Specifically, such a crosslinking reaction type organic resin can be obtained by using an epoxy group-containing synthetic resin emulsion as the organic resin and a hydrazino group-containing compound as the crosslinking agent. Examples of the hydrazino group-containing compound include malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, and the like, and hydrazino group-containing polymers.

Further, as the first refurbishing paint, those containing an infrared reflective pigment in addition to the crosslinking reaction type organic resin are suitable. The infrared reflective pigment in the first renovation paint is mixed within a range in which the pigment volume concentration is 60 to 90% (preferably 60 to 85%, more preferably 60 to 80%) (excluding 60%). It is desirable. With such a pigment volume concentration, it is possible to maintain a balance of each property (infrared reflectivity, water vapor permeability, elongation rate, tensile product ratio, etc.) in the laminated coating film.
In the application of the first renovation paint, a painting tool such as a spray gun, a roller, or a brush can be used. The coating amount is usually about 0.1 to ² kg / m ² (preferably 0.2 to 1 kg / m ² , more preferably 0.3 to 0.8 kg / m ² ) in terms of solid content.

In the present invention, the second renovation paint can be applied after the first renovation paint is applied. By this step, various colors can be imparted or the gloss of the coating film surface can be adjusted. The coating film properties such as weather resistance and water resistance in the laminated coating film can also be enhanced. As the second recoating paint, a paint that does not impair the properties of the laminated coating film may be selected, but a paint using a crosslinking reaction type organic resin as a binder is preferable.
The coating amount of the second renovation paint is desirably smaller than that of the first renovation paint, and is generally 0.05 to 0.5 kg / m ² (preferably 0.1 to 0. 0 in terms of solid content). 3 kg / ^{m 2,} more preferably from 0.1~0.25kg / ^{m 2)} approximately. With such a coating amount, the characteristics of the first renovation paint can be fully utilized.
In painting, painting tools such as a spray gun, a roller, and a brush can be used.

  Examples and Comparative Examples are shown below to clarify the features of the present invention.

[Example 1]
On one side of a slate plate (thickness 6 mm), an exterior thick coating material E (resin content 22) mainly composed of acrylic thermoplastic resin (Tg−40 ° C.), titanium oxide, calcium carbonate, chlorite, and rubber powder. Weight%) in a ball shape, and then press the convex portion of the ball with a plastic roller with mineral spirits to form a 4-8 mm coating film with trapezoidal cross section, which promotes weather resistance An old coating film was exposed for 400 hours with a test machine “I Super UV Tester” (manufactured by Iwasaki Electric Co., Ltd.).
Next, after spray-coating paint A at a coating amount of 0.5 kg / m ² on this old coating film, residential glass wool (thickness 100 mm) on the back surface (surface opposite to the coating surface) of the slate plate and A test body was produced by sequentially laminating slate plates (thickness 6 mm). In addition, the laminated body which consists of a slate board (thickness 6mm), residential glass wool (thickness 100mm), and a slate board (thickness 6mm) is equivalent to a heat insulating wall, and its heat transmissivity is 0.39W / (M ² · K).
About the obtained test body, the infrared lamp (output 250W) was irradiated for 8 hours from the distance of 40 cm from the coating-film surface, Then, the external appearance change was observed visually. As a result, no abnormality was observed.

In addition, the coating material A in Example 1 is 3.5 parts by volume of titanium oxide and 0.1% of yellow iron oxide with respect to 100 parts by volume of the solid content of resin 1 (carboxyl group / epoxy group-containing acrylic resin emulsion, Tg 0 ° C.). This is a gray paint having a pigment volume concentration of 62%, containing 3 parts by volume, 0.5 parts by volume of the petal, 0.3 parts by volume of phthalocyanine blue, and 158 parts by volume of heavy calcium carbonate.
The coating film formed with this paint A had an infrared reflectance of 64%, a water vapor transmission rate of 56 g / m ² · 24 h, an elongation at 20 ° C. of 55%, and a tensile product ratio of 0.46. The infrared reflectance was measured with a spectrophotometer (“UV-3100” manufactured by Shimadzu Corporation).

[Example 2]
A test specimen was prepared in the same manner as in Example 1 except that paint A was applied, and paint M was further spray-coated at a coating amount of 0.2 kg / m ² .
The coating M is 3.5 parts by volume of titanium oxide and 0.3 parts by volume of yellow iron oxide with respect to 100 parts by volume of the solid content of resin 2 (alkoxysilyl group-containing acrylic resin emulsion, Tg 30 ° C.). Is a gray paint having a pigment volume concentration of 4%, containing 0.5 part by volume and 0.3 part by volume of phthalocyanine blue.
In the multilayer coating film of the paint A and the paint M, the infrared reflectance was 66%, the water vapor transmission rate was 54 g / m ² · 24 h, the elongation at 20 ° C. was 58%, and the tensile product ratio was 0.47. .
When the test was performed on the obtained specimen in the same manner as in Example 1, no abnormality was found.

[Example 3]
A specimen was prepared in the same manner as in Example 1 except that paint B was used instead of paint A.
In addition, the coating material B is 3.5 volume of titanium oxide with respect to 100 volume parts of solid content of resin 3 (The mixture (epoxy group containing acrylic resin emulsion and adipic acid dihydrazide (solid content ratio 100: 5), Tg0 degreeC)). Part, 0.3 parts by volume of yellow iron oxide, 0.5 parts by volume of petals, 0.3 parts by volume of phthalocyanine blue, and 158 parts by weight of heavy calcium carbonate. It is a paint.
The formed coating film B had an infrared reflectance of 64%, a water vapor transmission rate of 58 g / m ² · 24 h, an elongation at 20 ° C. of 72%, and a tensile product ratio of 0.49.
When the test was performed on the obtained specimen in the same manner as in Example 1, no abnormality was found.

[Example 4]
A test specimen was prepared in the same manner as in Example 3 except that paint B was applied and spray paint was further applied with paint M at a coating amount of 0.2 kg / m ² .
In the multilayer coating film of the paint B and the paint M, the infrared reflectance was 66%, the water vapor transmission rate was 55 g / m ² · 24 h, the elongation at 20 ° C. was 74%, and the tensile product ratio was 0.48. .
When the test was performed on the obtained specimen in the same manner as in Example 1, no abnormality was found.

[Comparative Example 1]
A specimen was prepared in the same manner as in Example 1 except that paint C was used in place of paint A.
The coating material C is 3.5 parts by volume of titanium oxide and 0.3 volume of yellow iron oxide with respect to 100 parts by volume of the solid content of resin 4 (carboxyl group / epoxy group-containing acrylic resin emulsion, Tg-15 ° C.). This is a gray paint having a pigment volume concentration of 28%, containing 0.5 parts by volume, petal 0.5 parts by volume, phthalocyanine blue 0.3 parts by volume, and heavy calcium carbonate 34 parts by volume.
The formed film of paint C had an infrared reflectance of 65%, a water vapor permeability of 27 g / m ² · 24 h, an elongation at 20 ° C. of 124%, and a tensile product ratio of 0.28.
When the test was performed on the obtained specimen in the same manner as in Example 1, the coating film was swollen.

[Comparative Example 2]
A specimen was prepared in the same manner as in Example 1 except that paint D was used instead of paint A.
In addition, the coating material D has 3.5 parts by volume of titanium oxide, 0.3 parts by volume of yellow iron oxide, and 0.5% by weight of the petal relative to 100 parts by volume of the solid content of the resin 5 (acrylic resin emulsion, Tg 0 ° C.). It is a gray paint having a pigment volume concentration of 62%, containing 0.3 parts by volume of phthalocyanine blue and 158 parts by weight of heavy calcium carbonate.
The coating film formed of the paint D had an infrared reflectance of 64%, a water vapor transmission rate of 42 g / m ² · 24 h, an elongation at 20 ° C. of 56%, and a tensile product ratio of 0.23.
When the test was performed on the obtained specimen in the same manner as in Example 1, the coating film was swollen.

[Comparative Example 3]
A specimen was prepared in the same manner as in Example 1 except that paint E was used instead of paint A.
In addition, with respect to the solid content of resin 5 (acrylic resin emulsion, Tg 0 ° C.) 100 parts by volume, paint E is 3.8 parts by volume of titanium oxide, 0.2 parts by volume of yellow iron oxide, 0.1 This is a gray paint having a pigment volume concentration of 62%, containing 0.4 parts by volume of carbon black, 158 parts by volume of heavy calcium carbonate.
The formed coating film E had an infrared reflectance of 13%, a water vapor permeability of 42 g / m ² · 24 h, an elongation at 20 ° C. of 56%, and a tensile product ratio of 0.23.
When the test was performed on the obtained specimen in the same manner as in Example 1, the coating film was swollen.

Claims (3)

A method for refurbishing a building outer wall by applying and laminating at least one type of refurbishing paint to an old paint film surface formed on the outdoor side of the building outer wall,
(1) The outer wall is a heat insulating wall having a thermal conductivity of 5.0 W / (m ² · K) or less, and (2) the coating film formed by a paint having an organic resin as a binder. (3) The laminated coating film by the refurbishing paint is a coating film containing a crosslinking reaction type organic resin as a binder,
Of the renovation paints, at least one includes an infrared reflective pigment,
The reconstituted paint has a pigment volume concentration of 60 to 90% (excluding 60%),
The laminated coating film has infrared reflectivity and water vapor permeability, an elongation at 20 ° C. of 2 to 120%, and a tensile product ratio according to the following formula of 0.3 or more. How to renovate the building exterior. <Formula> “Ratio of tensile product” = “Tensile product at 60 ° C.” / “Tensile product at 20 ° C.” The cross-linking reaction type organic resin is at least one selected from the group consisting of vinyl acetate resin, vinyl chloride resin, epoxy resin, acrylic resin, urethane resin, acrylic silicon resin, and fluororesin. The method of renovating the building outer wall according to 1. The infrared reflective pigment is selected from the group consisting of aluminum flakes, titanium oxide, barium sulfate, zinc oxide, iron oxide, magnesium oxide, alumina, antimony oxide, zirconium oxide, yttrium oxide, indium oxide, silica, magnesium silicate, and calcium carbonate. The method for refurbishing a building outer wall according to claim 1 or 2, wherein the method is at least one selected.