JP4732214B2 - Painting method - Google Patents

Description

  The present invention relates to a coating method capable of forming a coating film having excellent water repellency.

Conventionally, water-repellent paints are known as materials for imparting waterproofness, antifouling properties, etc. to the surface of buildings, civil engineering structures and the like. Examples of water-repellent paints include those containing a fluororesin, and the coating film surface formed from these has a high contact angle with water, repels water by reducing the contact area with water, Water resistance, anti-contamination property, etc. can be imparted.
In recent years, in the field of paints, there has been a growing demand from solvent-based to water-based systems.

  For example, Patent Document 1 describes a method of coating an inorganic building material surface with an aqueous paint obtained by blending a specific aqueous water repellent with an aqueous resin liquid. However, the coating film obtained by the method of Patent Document 1 can repel water to some extent, but water droplets may remain on the coating film surface. If such water droplets are vaporized as they are, there is a risk of causing stains and the like. In the method of Patent Document 1, the water repellent effect may be impaired over time after the coating film is formed.

  The present invention has been made in view of the problems as described above, and suppresses a decrease in the water-repellent effect after forming the coating film, and can form a coating film capable of stably exhibiting excellent water-repellent performance. The purpose is to obtain a method.

JP 2003-301139 A

  As a result of intensive studies to achieve the above object, the present inventor has mixed a specific acrylic resin and silicone resin in the emulsion particles after applying a permeable water absorption preventing material as a primer to the base material. The inventors have conceived a method for applying an aqueous topcoat material containing a synthetic resin emulsion as a binder, and have completed the present invention.

  That is, the present invention has the following characteristics.

1. After applying a permeable water absorption preventing material as a primer on the surface of the substrate,
Synthetic resin emulsion (A) in which acrylic resin derived from (meth) acrylic acid alkyl ester and silicone resin derived from cyclic siloxane compound are mixed in emulsion particles at a weight ratio of 99: 1 to 30:70 is used as a binder. Including
A coating method comprising applying an aqueous topcoat material containing a powder (B) having an average particle size of 0.5 to 500 μm within a range where the pigment volume concentration is 30 to 90%.

2. After applying a permeable water absorption preventing material as a primer on the surface of the substrate,
A synthetic resin emulsion in which an acrylic resin derived from a (meth) acrylic acid alkyl ester and a silicone resin derived from a cyclic siloxane compound are mixed in the emulsion particles at a weight ratio of 99: 1 to 30:70, and (meth) An outer layer in which an acrylic resin derived from an alkyl acrylate ester and a silicone resin derived from a cyclic siloxane compound are mixed, and an inner layer containing an acrylic resin derived from an alkyl (meth) acrylate, and the acrylic resin in the outer layer A multilayer structure type synthetic resin emulsion (A-1) in which the glass transition temperature of the acrylic resin in the inner layer is set lower than the glass transition temperature is included as a binder,
A coating method comprising applying an aqueous topcoat material containing a powder (B) having an average particle size of 0.5 to 500 μm within a range where the pigment volume concentration is 30 to 90%.

  In the coating method of the present invention, an undercoating material composed of a permeable water absorption preventing material and a high pigment volume concentration aqueous overcoating material using a specific synthetic resin emulsion in which an acrylic resin and a silicone resin are combined are laminated. The coating film obtained by such a method exhibits excellent water repellency due to the synergistic effect of the undercoat material and the top coat material, and can maintain the initial water repellency for a long period of time. Excellent effects can be exhibited in the properties, efflorescence resistance, adhesion and the like.

  Hereinafter, the best mode for carrying out the present invention will be described.

  The present invention can be used mainly for painting buildings and civil engineering structures. Examples of applicable base materials include concrete, mortar, fiber-mixed cement board, cement calcium silicate board, slag cement pearlite board, ALC board, siding board, and extrusion-molded board. As long as the effects of the present invention can be obtained, these substrates may have surface-treated surfaces or may have an old coating film or the like.

  In the present invention, a permeable water absorption preventing material is first applied as a primer to the surface of the base material as described above. Such a permeable water absorption preventive material penetrates deeply into a base material such as concrete or mortar to form a water-repellent layer and blocks the intrusion of water, carbon dioxide gas, etc. from the outside. This prevents the strength from decreasing due to oxidization, and further suppresses the corrosion of steel frames, reinforcing bars and the like existing inside the base material. Moreover, the function which prevents the efflorescence generation | occurrence | production in the base-material surface layer by transfer of the calcium component inside a base material can also be exhibited.

  The permeable water absorption preventing material is not particularly limited as long as it exhibits the above-mentioned performance, and a known or commercially available material can be used. However, in consideration of workability, environmental hygiene, etc., an aqueous material Is preferred. When an aqueous permeable water absorption preventing material is used, coating is possible even when the base material contains water. Such penetrable water absorption preventing materials include hydrolyzable silane compounds and silicone resins that have been made into aqueous emulsions with various emulsifiers, or these aqueous emulsions, acrylic resins, acrylic silicone resins, fluororesins, urethanes. Examples include composites of resin-based and cross-linked resin-based synthetic resin emulsions.

  Among these, as hydrolyzed silane compounds, for example, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltripropoxysilane, ethyltributoxysilane , Propyltrimethoxysilane, propyltriethoxysilane, propyltripropoxysilane, propyltributoxysilane, butyltrimethoxysilane, butyltriethoxysilane, butyltripropoxysilane, butyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, Dimethyldipropoxysilane, dimethyldibutoxysilane, diethyldimethylsilane, diethyldiethoxysilane, diethyldipropoxysilane, diethyl Dibutoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, hexyltripropoxysilane, octyltrimethoxysilane, octyltriethoxysilane, octyltripropoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, octadecyltrimethoxysilane, phenyl Examples include trimethoxysilane and vinyltrimethoxysilane. These can be used individually or in mixture of several types.

  In the permeable water absorption preventing material in the present invention, inorganic color pigments, organic color pigments, extender pigments, plasticizers, film-forming aids, antiseptics, antifungal agents, antifoaming agents that are usually used in paints as necessary Additives such as agents, leveling agents, pigment dispersants, anti-settling agents, anti-sagging agents, and matting agents can be used alone or in combination.

The means for applying the permeable water absorption preventing material is not particularly limited, and a known coating method such as brush coating, spray coating, or roller coating can be used. When the base material is a dry building material, it can be painted in the factory by a roll coater, a flow coater or the like. Coat-weight osmotic water absorption preventing agent may be appropriately set but is usually 0.05kg ^{/ m 2} ~0.4kg ^/ m 2 approximately. The drying after applying the permeable water absorption preventing material is usually performed at room temperature, but can be heated as necessary.

  In this invention, after apply | coating the said primer, the aqueous | water-based topcoat containing a specific synthetic resin emulsion (A) and a granular material (B) is applied.

Among these, in the synthetic resin emulsion (A) (hereinafter referred to as “component (A)”), acrylic resin derived from (meth) acrylic acid alkyl ester and silicone resin derived from cyclic siloxane compound are mixed in emulsion particles. Is. The form of the acrylic resin and the silicone resin in the component (A) is not particularly limited, and may be a uniformly mixed form, but a form separated from each other by a sea-island structure or the like is preferable.
The weight ratio of the acrylic resin and the silicone resin in the component (A) is usually 99: 1 to 30:70, preferably 97: 3 to 40:60. By mixing both components in such a ratio, a paint having various physical properties such as water repellency, film-forming property, and crack prevention property can be obtained.

  Such component (A) imparts excellent water repellency to the formed coating film of the aqueous topcoat material. In addition, by using such a component (A) as a binder for an aqueous topcoat material, the initial water-repellent effect can be maintained for a long time after the coating film is formed. Furthermore, since the aqueous | water-based topcoat material containing such (A) component is excellent also in adhesiveness with a basecoat material, it can exhibit the stable coating-film performance.

  (A) The acrylic resin which comprises a component is a polymer which has (meth) acrylic-acid alkylester as a main component, and copolymerizes another monomer as needed. Examples of (meth) acrylic acid alkyl esters include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and t-butyl (meth) acrylate. , N-amyl (meth) acrylate, isoamyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, octadecyl (Meth) acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate and the like. The amount of such (meth) acrylic acid alkyl ester is usually 30% by weight or more, preferably 40 to 99.9% by weight, more preferably 50 to 99.9%, based on all monomers constituting the component (A). 5% by weight.

  Examples of other monomers include carboxyl group-containing monomers, amino group-containing monomers, pyridine monomers, hydroxyl group-containing monomers, nitrile group-containing monomers, amide group-containing monomers, epoxy group-containing monomers, carbonyl group-containing monomers, and alkoxysilyl group-containing monomers. And aromatic monomers. The usage-amount of these monomers is 0.1 to 60 weight% normally with respect to all the monomers which comprise (A) component, Preferably it is 0.5 to 50 weight%.

  Among these, when a carboxyl group-containing monomer is copolymerized to obtain a carboxyl group-containing acrylic resin, the stability of the component (A) can be increased, and a compound capable of reacting with a carboxyl group is added separately. Therefore, various physical properties of the coating film can be improved. Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, crotonic acid, maleic acid or a monoalkyl ester thereof, itaconic acid or a monoalkyl ester thereof, fumaric acid or a monoalkyl ester thereof. Among these, at least one selected from acrylic acid and methacrylic acid is particularly preferable. The usage-amount of a carboxyl group-containing monomer is 0.1 to 40 weight% normally with respect to all the monomers which comprise (A) component, Preferably it is 0.5 to 20 weight%.

  The silicone resin in component (A) is obtained by polymerizing a cyclic siloxane compound. Examples of the cyclic siloxane compound include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and the like. When polymerizing such a cyclic siloxane compound, a linear siloxane compound, a branched siloxane compound, an alkoxysilane compound, or the like can also be used. Of these, as the alkoxysilane compound, a silane compound having one or more alkoxyl groups in the molecule can be used. For example, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, vinylmethyldimethoxysilane, γ- Silane coupling agents such as (meth) acryloyloxytrimethoxysilane and 3-mercaptopropyltrimethoxysilane can be used. The average molecular weight of the silicone resin is usually 10,000 or more, preferably 50,000 or more.

  The component (A) in the water-based top coating material is a synthetic resin emulsion in which an acrylic resin and a silicone resin are mixed as described above, and has an outer layer in which an acrylic resin and a silicone resin are mixed, and an inner layer containing the acrylic resin. A multilayer structure type synthetic resin emulsion (A-1) (hereinafter referred to as “component (A-1)”) in which the glass transition temperature of the acrylic resin in the inner layer is set lower than the glass transition temperature of the acrylic resin in the outer layer is preferable. is there. When such a component (A-1) is used, it is possible to obtain a more remarkable effect in water repellency, and the coating performance such as adhesion and crack prevention is enhanced, which is also preferable in terms of waterproofness. It will be a thing. The weight ratio of the outer layer to the inner layer is usually 80:20 to 20:80, preferably 70:30 to 30:70.

Such a component (A-1) can be obtained by, for example, a method in which an acrylic resin constituting the inner layer is emulsion-polymerized and then an acrylic resin and a silicone resin constituting the outer layer are emulsion-polymerized. In the component (A-1), the silicone resin as described above may be contained as a resin constituting the inner layer. By including a silicone resin in the inner layer, it is possible to enhance crack prevention properties and the like.
Here, the glass transition temperature (hereinafter referred to as “Tg”) of the acrylic resin constituting the inner layer may be usually set to −60 to 20 ° C. (preferably −50 to 10 ° C.). Tg of an outer layer is 20-100 degreeC normally (preferably 30-90 degreeC). When the Tg of the acrylic resin in each layer is within such a range, the above-described effects can be stably obtained. Note that Tg in the present invention is a value obtained by the Fox calculation formula.

  In the present invention, when the carboxyl group-containing acrylic resin is contained in the component (A), effects such as swelling prevention and peeling prevention can be enhanced by separately adding a compound capable of reacting with the carboxyl group. Furthermore, the tackiness of the coating film surface is reduced and the stain resistance is increased. Examples of such a compound include compounds having one or more functional groups selected from a carbodiimide group, an epoxy group, an aziridine group, an oxazoline group, and the like. Among these, in the present invention, a reactive compound having an epoxy group is particularly suitable.

  Examples of the reactive compound having an epoxy group include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol poly Examples thereof include glycidyl ether, diglycerol polyglycidyl ether, polyhydroxyalkane polyglycidyl ether, and sorbitol polyglycidyl ether. In addition, a water-soluble resin or emulsion made of a polymer (homopolymer or copolymer) of an epoxy group-containing monomer can also be used. The mixing amount of such a compound is usually 0.1 to 50 parts by weight, preferably 0.3 to 20 parts by weight with respect to 100 parts by weight of the resin solid content of the component (A).

  In addition to the above-mentioned component (A), the water-based top coating material has a powder (B) (hereinafter referred to as “component (B)”) having an average particle size of 0.5 to 500 μm as an essential component, and this component (B) is a pigment. It mix | blends within the range from which volume concentration will be 30 to 90%. In the present invention, by adding such a component (B) to the aqueous topcoat material, a fine uneven structure is imparted to the surface of the topcoat material coating, and the contact area when water droplets contact the coating is reduced. And an excellent water repellent effect is obtained by the combined action with the component (A).

  The range of the suitable average particle diameter in (B) component is 1-200 micrometers (further 3-100 micrometers). When the average particle size of the component (B) is out of the above range, it is difficult to obtain a sufficient effect in water repellency. Specifically, when the average particle size of the component (B) is too large, the surface of the coating film becomes too rough and water may enter the coating film. When the average particle size is too small, it becomes difficult to form a fine concavo-convex structure that contributes to improving water repellency. In addition, the average particle diameter of (B) component is based on observation with a transmission electron microscope, and is a value obtained by determining the particle diameter distribution (number basis) when the equivalent circle diameter of each particle is the diameter. is there.

  As the component (B), the material is not particularly limited, and various powders can be used. For example, heavy calcium carbonate, kaolin, clay, porcelain clay, china clay, talc, barite powder, barium sulfate, barium carbonate, magnesium carbonate, silica powder, aluminum hydroxide and the like can be mentioned. In addition, marble, granite, serpentine, granite, fluorite, cryolite, feldspar, limestone, quartzite, quartz sand, crushed stone, mica, siliceous shale, and pulverized products thereof, ceramic pulverized product, ceramic pulverized product, glass pulverized product Products, resin pulverized products, rubber particles, plastic pieces, metal particles, etc., and those whose surfaces are colored and coated can also be used.

  The pigment volume concentration of the component (B) in the aqueous top coating material is 30 to 90%, preferably 40 to 85%, more preferably 50 to 80%. When the pigment volume concentration of the component (B) is smaller than 30%, it is difficult to obtain a sufficient water repellent effect, and when it is larger than 90%, the coating film is likely to be cracked. In addition, the pigment volume concentration of (B) component in this invention is a volume percentage of (B) component contained in a dry coating film, and is calculated | required by calculation from the compounding quantity of the binder which comprises a coating material, and a granular material. Value.

  As long as the water-repellent effect by the above-mentioned components is not significantly impaired, the water-based top coating material is mixed with a granular component other than the above-mentioned component (B), for example, an inorganic color pigment, an organic color pigment, etc. You can also By mixing such a color pigment, the paint can be adjusted to a desired hue. In this case, the pigment volume concentration of the entire paint may be about 40 to 90% (preferably 50 to 85%). In addition, the water-based top coating material can also contain components that can be used in ordinary paints. Examples of such components include aggregates, fibers, thickeners, film-forming aids, leveling agents, wetting agents, plasticizers, antifreezing agents, pH adjusting agents, antiseptics, antifungal agents, and algaeproofing agents. , Antibacterial agents, dispersants, antifoaming agents, adsorbents, water repellents, crosslinking agents, ultraviolet absorbers, antioxidants, catalysts and the like. The aqueous top coating material can be produced by uniformly mixing the above components by a conventional method.

  In the present invention, a coating film exhibiting excellent water repellency can be obtained by applying such a water-based overcoating material after applying a primer. Specifically, a coating film having a contact angle with water of 110 ° or more (preferably 120 ° or more, more preferably 130 ° or more, and further preferably 140 ° or more) can be formed. In addition, the contact angle said here is a value of the static contact angle measured with a contact angle meter.

  As a method for coating the aqueous topcoat material, a known method can be employed, and for example, spray coating, roller coating, brush coating, and the like are possible. When painting dry building materials in a factory, it is also possible to paint with a roll coater, a flow coater or the like. The water-based top coating material in the present invention also has an advantage that defects such as repelling are less likely to occur during coating.

The coating amount for applying the aqueous topcoat material may be appropriately selected, but is usually about 0.1 to 0.5 kg / m ² . At the time of application, the viscosity of the paint can be appropriately adjusted by diluting with water or the like. The dilution ratio is usually about 0 to 20% by weight. Drying after the application of the aqueous topcoat material is usually carried out at room temperature, but heating is also possible.

  Examples are given below to clarify the features of the present invention.

(Manufacture of water-based coating materials)
In accordance with the formulation shown in Table 1, each raw material was mixed and stirred by a conventional method to produce an aqueous topcoat material. The following were used as raw materials.

Resin 1: Multilayer structure type synthetic resin emulsion Outer layer: Acrylic resin (Tg 45 ° C., component: t-butyl methacrylate, n-butyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid), silicone resin (component) Hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane), weight ratio of outer layer acrylic resin to silicone resin 80:20,
Inner layer: acrylic resin (Tg-50 ° C., constituent components: n-butyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate),
Weight ratio of outer layer to inner layer 45:55, solid content 50% by weight, carboxyl group-containing monomer 3% by weight

Resin 2: Multilayer structure type synthetic resin emulsion Outer layer: Acrylic resin (Tg 45 ° C., component: t-butyl methacrylate, n-butyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid), silicone resin (component) Hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane), weight ratio of outer acrylic resin to outer silicone resin 80:20,
Inner layer: acrylic resin (Tg-50 ° C., component: n-butyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate), silicone resin (component: hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclo) Pentasiloxane), weight ratio of inner layer acrylic resin to inner layer silicone resin 80:20,
Weight ratio of outer layer to inner layer 45:55, solid content 50% by weight, carboxyl group-containing monomer 3% by weight

Resin 3: Multi-layer structure type synthetic resin emulsion outer layer; acrylic resin (Tg 45 ° C., component: t-butyl methacrylate, n-butyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid),
Inner layer: silicone resin (component: hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane),
Weight ratio of outer layer to inner layer 70:30, solid content 50% by weight, carboxyl group-containing monomer 3% by weight

Resin 4: Multi-layer structure type synthetic resin emulsion outer layer; acrylic resin (Tg 45 ° C., component: t-butyl methacrylate, n-butyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid),
Inner layer: acrylic resin (Tg-50 ° C., constituent components: n-butyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate),
Weight ratio of outer layer to inner layer 50:50, solid content 50% by weight, carboxyl group-containing monomer 3% by weight

Resin 5: Acrylic resin emulsion (Tg 12 ° C., component: t-butyl methacrylate, n-butyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methacrylic acid; solid content 50% by weight, carboxyl group-containing monomer 3% by weight )

-Granule 1: Silica powder (average particle size 18 μm, oil absorption 10 ml / 100 g, specific gravity 2.7)
Powder body 2: Titanium oxide (average particle diameter 0.2 μm, oil absorption 13 ml / 100 g, specific gravity 4.2)
・ Water repellent: dimethylsiloxane compound dispersion, solid content 50% by weight)
・ Film-forming auxiliary: 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate ・ Dispersant: polycarboxylic acid-based dispersant (solid content 30% by weight)
・ Thickener: Polyurethane thickener (solid content 30% by weight)
-Antifoaming agent: Silicon-based antifoaming agent (solid content 50% by weight)

Example 1
Each test was carried out by the following method using an aqueous emulsion type permeable water absorption preventing material mainly composed of hexyltriethoxysilane as an undercoat material, and using an aqueous overcoat material 1 shown in Table 1 as an overcoat material. did. The test results are shown in Table 2. In Example 1, good results could be obtained in any test.

(1) Contact angle measurement A slate plate of 150 × 70 × 3 mm is spray-coated with a primer at a coating amount of 0.1 kg / m ² , and is 8 at a temperature of 23 ° C. and a relative humidity of 50% (hereinafter, standard state). After drying for a period of time, a water-based top coating material was spray-coated at a coating amount of 0.2 kg / m ² and dried for 14 days in a standard state to obtain a test specimen. 0.2 cc of deionized water was dropped on the surface of the test specimen, and the contact angle immediately after dropping was measured with a CA-A type contact angle measuring device manufactured by Kyowa Interface Science Co., Ltd.

(2) Water slidability test A slate plate of 150 × 70 × 3 mm was spray-coated with a primer at a coating amount of 0.1 kg / m ² , dried in standard conditions for 8 hours, and then coated with a water-based topcoat at a coating amount of 0. The test specimen was spray-coated at ² kg / m ² and dried for 14 days in a standard state. The test specimen was tilted by 15 degrees with respect to the horizontal plane, and the water droplet sliding state and the presence or absence of a water drop trace after dropping were visually observed when deionized water was continuously dropped onto the coating film surface of the test specimen. The evaluation criteria are `` ◎ '' when the water droplet slid into a spherical shape and no water droplet trace left, `` ○ '' when the water droplet slid into a spherical shape and almost no water droplet trace left, “Δ” indicates that the water droplets remained, and “x” indicates that the water droplets did not slide into a spherical shape but remained.

(3) Adhesion test A slate plate of 150 × 70 × 3 mm was spray-coated with an undercoat material at a coating amount of 0.1 kg / m ² , dried in a standard state for 8 hours, and then coated with an aqueous topcoat material of 0 A specimen was spray-coated at 2 kg / m 2 and cured for 14 days. After this test body was immersed in 23 ° C. water for 168 hours, the adhesion was evaluated by a cross-cut tape method according to JIS K 5600-5-6. The evaluation criteria are “」 ”when the defect area is less than 5%,“ ◯ ”when the defect area is 5% or more and less than 15%, and“ △ ”when the defect area is 15% or more and less than 35%. “,” And “x” are those having a defect area of 35% or more.

(4) Wet and cold repeatability test We spray-coated the undercoat material at a coating amount of 0.1 kg / m ² on a 150 × 70 × 3 mm slate plate, and after drying for 8 hours in a standard state, apply an aqueous topcoat material. The test specimen was spray-coated at a weight of 0.2 kg / m 2 and cured for 14 days. The specimen was immersed in water at 23 ° C. for 18 hours, immediately cooled in a thermostat kept at −20 ° C. for 3 hours, and then heated in another thermostat kept at 50 ° C. for 3 hours. After this operation was repeated 10 times, it was placed in a standard state for about 1 hour, and the state of the coating film surface was visually observed. Evaluation criteria are based on checking the degree of occurrence of abnormalities (cracking, swelling, and peeling). “◎” indicates that no abnormality occurred, “○” indicates that no abnormality occurred, “△” indicates that a part of the mark was generated, and “X” indicates a case where the abnormality was significantly generated.

(5) Water repellency persistence test On a 150 × 70 × 3 mm slate plate, spray the base material at a coating amount of 0.1 kg / m ² , dry in standard condition for 8 hours, and then apply the aqueous top coating material. A test specimen was spray-coated at an amount of 0.2 kg / m ² and dried for 14 days in a standard state. 0.2 cc of deionized water was dropped on the surface of the test specimen, and the contact angle immediately after dropping was measured with a CA-A type contact angle measuring device manufactured by Kyowa Interface Science Co., Ltd.
Next, the test specimen was immersed in water at 23 ° C. for 3 hours, dried in a standard state for 1 hour, and then contact angle was measured in the same manner. In this test, the contact angle after immersion in water was evaluated by confirming how much the contact angle decreased with respect to the initial contact angle. The evaluation criteria are “◯” when the contact angle decrease after water immersion is less than 5 degrees, “△” when 5 degrees or more and less than 10 degrees, and “×” when 10 degrees or more. "

(Example 2)
The same test as in Example 1 was conducted using an aqueous emulsion type permeable water absorption preventing material mainly composed of hexyltriethoxysilane as the undercoat material, and using the aqueous overcoat material 2 shown in Table 1 as the overcoat material. went. The test results are shown in Table 2.

(Example 3)
The same test as in Example 1 was performed using an aqueous emulsion type permeable water absorption preventing material mainly composed of hexyltriethoxysilane as an undercoat material, and using an aqueous overcoat material 3 shown in Table 1 as an overcoat material. went. The test results are shown in Table 2.

Example 4
The same test as in Example 1 was performed using an aqueous emulsion type permeable water absorption preventing material mainly composed of hexyltriethoxysilane as an undercoat material, and using an aqueous overcoat material 4 shown in Table 1 as an overcoat material. went. The test results are shown in Table 2.

(Comparative Example 1)
The same test as in Example 1 was performed using an aqueous emulsion type permeable water absorption preventing material mainly composed of hexyltriethoxysilane as an undercoat material, and using an aqueous overcoat material 5 shown in Table 1 as an overcoat material. went. The test results are shown in Table 2.

(Comparative Example 2)
The same test as in Example 1 was performed using an aqueous emulsion type permeable water absorption preventing material mainly composed of hexyltriethoxysilane as the undercoat material, and using the aqueous overcoat material 6 shown in Table 1 as the overcoat material. went. The test results are shown in Table 2.

(Comparative Example 3)
The same test as in Example 1 was performed using an aqueous undercoating material mainly composed of an epoxy resin emulsion as the undercoating material and using the aqueous overcoating material 6 shown in Table 1 as the overcoating material. The test results are shown in Table 2.

(Comparative Example 4)
The same test as in Example 1 was performed using an aqueous emulsion type permeable water absorption preventing material mainly composed of hexyltriethoxysilane as the undercoat material, and using the aqueous overcoat material 7 shown in Table 1 as the overcoat material. went. The test results are shown in Table 2.

(Comparative Example 5)
The same test as in Example 1 was performed using an aqueous emulsion type permeable water absorption preventing material mainly composed of hexyltriethoxysilane as the undercoat material, and using the aqueous overcoat material 8 shown in Table 1 as the overcoat material. went. The test results are shown in Table 2.

Claims (2)

After applying a permeable water absorption preventing material as a primer on the surface of the substrate,
Synthetic resin emulsion (A) in which acrylic resin derived from (meth) acrylic acid alkyl ester and silicone resin derived from cyclic siloxane compound are mixed in emulsion particles at a weight ratio of 99: 1 to 30:70 is used as a binder. Including
A coating method comprising applying an aqueous topcoat material containing a powder (B) having an average particle size of 0.5 to 500 μm within a range where the pigment volume concentration is 30 to 90%. After applying a permeable water absorption preventing material as a primer on the surface of the substrate,
A synthetic resin emulsion in which an acrylic resin derived from a (meth) acrylic acid alkyl ester and a silicone resin derived from a cyclic siloxane compound are mixed in the emulsion particles at a weight ratio of 99: 1 to 30:70, and (meth) An outer layer in which an acrylic resin derived from an alkyl acrylate ester and a silicone resin derived from a cyclic siloxane compound are mixed, and an inner layer containing an acrylic resin derived from an alkyl (meth) acrylate, and the acrylic resin in the outer layer A multilayer structure type synthetic resin emulsion (A-1) in which the glass transition temperature of the acrylic resin in the inner layer is set lower than the glass transition temperature is included as a binder,
A coating method comprising applying an aqueous topcoat material containing a powder (B) having an average particle size of 0.5 to 500 μm within a range where the pigment volume concentration is 30 to 90%.