Topcoat paint composition, multi-layer coating film, and repair method

Abstract

To provide a topcoat paint composition that can achieve both excellent film conformability and stain resistance in the resulting coating. [Solution] A water-based topcoat paint composition used to form a topcoat film on top of a primer film with an elongation rate of 120% or more and 400% or less formed on the exterior wall of a building, wherein the topcoat paint composition comprises an acrylic silicone resin composition, a pigment, and a plasticizer, the plasticizer comprising a first plasticizer having a boiling point of 200°C or more and less than 250°C, and a second plasticizer having a boiling point of 250°C or more and less than 300°C, and the total amount of plasticizers per 100 parts by mass of solids of the acrylic silicone resin composition is 10 parts by mass or more and 20 parts by mass or less.

Description

Technical Field

[0001] The present disclosure relates to a topcoat paint composition, a multilayer coating film, and a repair method.

Background Art

[0002] Conventionally, a method of forming a coating film on the outer wall surface is known to protect the outer wall of a building from deterioration. As such a coating film, a multilayer coating film including an undercoat coating film formed on the outer wall surface and a topcoat coating film formed on the upper layer of the undercoat coating film is known. The undercoat coating film is preferably capable of following displacements caused by displacements such as cracks in the building body or old coating films during renovation, while the topcoat coating film is required to have functions such as weather resistance and a favorable appearance (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As a resin component constituting the topcoat coating film, an acrylic silicone resin is known. A coating film formed of an acrylic silicone resin is preferably used because it has high weather resistance and stain resistance. On the other hand, since the above coating film is a relatively hard coating film, it may not have sufficient followability according to the displacement of the undercoat coating film. Therefore, it is considered that the durability of the coating film can be further enhanced by imparting the above followability to the topcoat coating film.

[0005] One way to impart flexibility to a topcoat is to add a plasticizer. However, simply adding a plasticizer has the drawback of reducing the stain resistance of the coating. Furthermore, in recent years, there has been a growing demand for topcoats with a matte appearance that gives a low gloss and a subdued impression. One way to achieve such a matte appearance is to increase the amount of pigment blended into the topcoat, but in this case, the coating becomes hard and brittle, making it even more difficult to achieve both flexibility and matte appearance.

[0006] This disclosure has been made in view of the above, and aims to provide a topcoat paint composition that can achieve both conformability and stain resistance of the formed coating film. [Means for solving the problem]

[0007] (1) This disclosure relates to an aqueous topcoat paint composition used to form a topcoat film on top of a primer film having an elongation of 120% or more and 400% or less formed on the exterior wall of a building, wherein the topcoat paint composition comprises an acrylic silicone resin composition, a pigment, and a plasticizer, wherein the plasticizer comprises a first plasticizer having a boiling point of 200°C or more and less than 250°C, and a second plasticizer having a boiling point of 250°C or more and less than 300°C, and the total amount of the plasticizers per 100 parts by mass of the solids content of the acrylic silicone resin composition is 10 parts by mass or more and 20 parts by mass or less.

[0008] (2) The topcoat paint composition according to (1), wherein the mass ratio of the first plasticizer to the second plasticizer (first plasticizer / second plasticizer) is 4 / 1 to 1 / 2.

[0009] (3) The present disclosure also relates to a multilayer coating film comprising a primer coating film formed by a primer coating composition and a topcoat coating film formed on the surface of the primer coating film by the topcoat coating composition described in (1) or (2), wherein the elongation of the primer coating film is 120% or more and 400% or less, and the 60-degree specular gloss of the surface of the topcoat coating film is 20 or less.

[0010] (4) The present disclosure also relates to a method for repairing the exterior wall of a building, comprising the step of applying the topcoat paint composition described in claim 1 to the surface of a primer coating with an elongation rate of 120% or more and 400% or less to form a topcoat coating, wherein the 60-degree specular gloss of the surface of the topcoat coating is 20 or less. [Effects of the Invention]

[0011] According to this disclosure, it is possible to provide a topcoat paint composition that can achieve both conformability and stain resistance of the formed coating film. [Modes for carrying out the invention]

[0012] The embodiments of this disclosure are described below. This disclosure is not limited to the embodiments described below.

[0013] <Topcoat paint composition> The topcoat paint composition is a water-based paint composition and includes an acrylic silicone resin composition, a pigment, and a plasticizer.

[0014] The acrylic silicone resin composition is contained, for example, in the form of an emulsion dispersed in a medium such as water. The acrylic silicone resin emulsion can be obtained, for example, by modifying an acrylic resin emulsion with a silicon-containing compound. This modification may be carried out during the synthesis of the acrylic resin emulsion or separately after synthesis. The acrylic resin emulsion can be synthesized by known polymerization methods such as emulsion polymerization using water as a medium. As the acrylic silicone resin emulsion, an alkoxysilyl group-containing acrylic resin emulsion is preferred because it has excellent stain resistance and weather resistance.

[0015] Acrylic silicone resin emulsions can be obtained, for example, by copolymerizing acrylic monomers, silyl group-containing monomers, and other monomers that can be copolymerized with the above monomers as needed. Alternatively, acrylic silicone resin emulsions can be obtained by modifying an acrylic resin emulsion obtained from the above acrylic monomers, etc., with the above silyl group-containing monomers.

[0016] Examples of the above-mentioned acrylic monomers include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, isobonyl (meth)acrylate, etc. These may be used individually or in combination of two or more. In this specification, "(meth)acrylate" means acrylate or methacrylate.

[0017] The above silyl group-containing monomers are not particularly limited as long as they contain a silyl group in their molecule, but examples include vinyltrimethoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, vinyltriethoxysilane, γ-(meth)acryloxypropyltriethoxysilane, γ-(meth)acryloxypropyltripropoxysilane, γ-(meth)acryloxypropyltributoxysilane, vinylmethyldimethoxysilane, γ-(meth)acryloxypropylmethyldimethoxysilane, vinylmethyldiethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, γ-(meth)acryloxypropylmethyldipropoxysilane, γ-(meth)acryloxy Examples include cypropylmethyldibutoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, γ-(meth)acryloxypropylmethyldimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, γ-(meth)acryloxypropylmethyldipropoxysilane, γ-(meth)acryloxypropylmethyldibutoxysilane, vinyldimethylmethoxysilane, vinyldimethylethoxysilane, γ-(meth)acryloxypropyldimethylethoxysilane, γ-(meth)acryloxypropyldimethylmethoxysilane, γ-(meth)acryloxypropyldimethylpropoxysilane, and γ-(meth)acryloxypropyldimethylbutoxysilane. These may be used individually or in combination of two or more.

[0018] The above-mentioned other monomers are not particularly limited as long as they are copolymerizable with the above-mentioned acrylic monomers and silyl group-containing monomers, but examples include aromatic hydrocarbon vinyl monomers such as styrene, α-methylstyrene, chlorostyrene, 4-hydroxystyrene, and vinyltoluene; vinyl esters and allyl compounds such as vinyl acetate, vinyl propionate, vinyl versatate, and diallyl phthalate; nitrile group-containing vinyl monomers such as (meth)acrylonitrile; epoxy group-containing vinyl monomers such as glycidyl (meth)acrylate; hydroxyl group-containing vinyl monomers such as 2-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxyethyl vinyl ether, hydroxystyrene, and hydroxyl group-containing vinyl-modified hydroxyalkyl vinyl monomers; vinyl methyl ether, propylene, and butadiene. These may be used individually or in combination of two or more.

[0019] The content of the above acrylic silicone resin composition in the topcoat paint composition is preferably 50 to 65% by mass. The solid content of the above acrylic silicone resin composition is preferably 40 to 60% by mass.

[0020] The pigments improve the weather resistance of the topcoat film formed and provide a matte finish. While not particularly limited, examples of such pigments include titanium dioxide, diatomaceous earth (silicon dioxide), calcium carbonate, kaolin clay, talc, barium sulfate, white carbon, carbon, red iron oxide, yellow ochre, and cyanine blue. These may be used individually or in combination of two or more. The above pigments may be subjected to inorganic or organic surface treatments to improve weather resistance and dispersibility. In addition to pigments, synthetic waxes such as polyethylene wax, resin beads, etc., may also be used in combination.

[0021] The above pigment is preferably present in an amount of 15 to 70% by mass relative to the total solid content of the topcoat paint composition. The above pigment is preferably present with an average particle size (D50) of 5 to 30 μm.

[0022] The plasticizer includes a first plasticizer having a boiling point of 200°C or higher and lower than 250°C and a second plasticizer having a boiling point of 250°C or higher and lower than 300°C. When a single type of plasticizer is contained in the topcoat paint composition, if the amount of the plasticizer is too small, sufficient followability of the coating film cannot be obtained, and if the amount of the plasticizer is too large, the stain resistance decreases. In the present embodiment, by including the two types of plasticizers in the topcoat paint composition, it is possible to achieve both followability and stain resistance of the formed topcoat film.

[0023] Examples of the first plasticizer include dipropylene glycol-n-butyl ether (boiling point: 230°C), diethylene glycol monobutyl ether (boiling point: 230°C), and the like. These may be used alone or in combination of two or more.

[0024] Examples of the second plasticizer include 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (Texanol) (boiling point: 255°C), 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (boiling point: 282°C), diethylene glycol dibutyl ether (boiling point: 255°C), tripropylene glycol n-butyl ether (boiling point: 275°C), and the like. These may be used alone or in combination of two or more.

[0025] The plasticizer may include plasticizers other than the first plasticizer and the second plasticizer within a range that does not inhibit the effects of the present disclosure. The plasticizer preferably consists of the first plasticizer and the second plasticizer.

[0026] The total content of the plasticizer in the topcoat paint composition is 10 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the solid content of the acrylic silicone resin composition. Thereby, it is possible to preferably achieve both followability and stain resistance of the formed topcoat film. From the above viewpoint, the total content of the plasticizer is preferably 12 parts by mass or more and 17 parts by mass or less.

[0027] The mass ratio (first plasticizer / second plasticizer) of the first plasticizer to the second plasticizer is preferably 4 / 1 to 1 / 2. This allows for a desirable balance between the conformability and stain resistance of the formed topcoat film. From the above viewpoint, the mass ratio (first plasticizer / second plasticizer) is more preferably 3 / 1 to 1 / 1.

[0028] (Other ingredients) The topcoat paint composition according to this embodiment contains a solvent (dispersion medium) in addition to the above. The solvent may be mainly water and may also contain other components with high water solubility (e.g., alcohols). The topcoat paint composition may also contain other components other than those mentioned above, such as additives, as needed. Specific examples of other components include, for example, antifreeze, preservatives, fungicides, antibacterial agents, defoaming agents, pigment dispersants, thickeners, leveling agents, wetting agents, rust inhibitors, compatibility aids, pH adjusters, fibers, matting agents, ultraviolet absorbers, antioxidants, light stabilizers, adsorbents, catalysts, and the like.

[0029] <Undercoat paint composition> The primer composition is a composition for forming a primer film with an elongation rate of 120% or more and 400% or less. The primer composition is not particularly limited as long as it can achieve the above-mentioned elongation rate of the primer film, but examples include primer compositions containing an aqueous acrylic emulsion.

[0030] The primer paint composition may, if necessary, contain components similar to those that may be included in the topcoat paint composition described above.

[0031] <Multi-layer coating> The above-mentioned primer paint composition forms a primer film on the surface of the exterior wall of the building to be painted. A topcoat paint composition is then formed on top of the primer film. In other words, a multi-layer coating consisting of a primer film and a topcoat film is formed on the surface of the object to be painted.

[0032] The elongation rate of the primer coating is 120% or more and 400% or less. In this specification and in the claims, "elongation rate" means the elongation rate obtained from the elongation at sample fracture, measured on a tensile testing machine under the conditions of temperature (23±2)°C and humidity (50±5)%. More specifically, the above "elongation rate" can be measured in accordance with the conditions of "7.26 Elongation test a) Elongation test under standard conditions" as specified in JIS A 6909. A primer coating with such an elongation rate has high adaptability to displacement caused by cracks in the coated object.

[0033] The 60-degree specular gloss of the topcoat film surface is preferably 20 or less. This allows for a desirable matte appearance to be imparted to the multi-layer coating. More preferably, the 60-degree specular gloss of the topcoat film surface is 15 or less. In this specification and the claims, 60-degree specular gloss means that it is measured by the method specified in JIS K 5600-4-7.

[0034] The thickness of the undercoat film is not particularly limited, but is, for example, 0.5 to 5 mm. The thickness of the topcoat film is not particularly limited, but is, for example, 30 to 100 μm.

[0035] <Method for forming a multi-layer coating (repair method)> The method for forming a multi-layer coating according to this embodiment is a method for forming the multi-layer coating on the surface of the exterior wall of a building to be coated. The building may be one in which a coating has already been formed on the surface of the exterior wall, and the method for forming the multi-layer coating may be performed as a method for renovating the building. Alternatively, the building may be a newly constructed building in which no coating has been formed on the surface of the exterior wall. The material of the exterior wall of the building on which the multi-layer coating is formed is not particularly limited and may be concrete, mortar, slate board, PC board, ALC board, wood, stone, plastic, metal, etc.

[0036] The method for forming a multilayer coating according to this embodiment includes the step of applying the topcoat paint composition to the surface of a primer coating having an elongation rate of 120% or more and 400% or less to form the topcoat coating. The primer coating may be formed by the primer paint composition. In this case, the method for forming a multilayer coating includes the step of forming the primer coating with the primer paint composition.

[0037] The method of applying the paint composition in the steps of forming the topcoat and undercoat coatings is not particularly limited, and a general method can be used. For example, a painting method using painting tools such as rollers, air sprayers, airless sprayers, and brushes can be used. The same applies to the undercoat paint composition. After application, the coating hardens and a coating film is formed after a certain period of time has elapsed. The steps of forming the topcoat and undercoat coatings may each be repeated multiple times. The paint compositions used in these steps may be of the same type or different types.

[0038] If the building to be coated is a building that already has a coating applied to it, a step may be taken to remove rust and other contaminants from the surface of the building by scraping prior to the formation of the multi-layer coating, but this step is not required. [Examples]

[0039] The contents of this disclosure will be described in more detail below based on the following examples. The contents of this disclosure are not limited to the following examples.

[0040] (Example 1) The topcoat paint composition according to Example 1 was prepared using the formulation shown in Table 1 below. In Table 1, Dawanol DPNB (Dow Chemical Company, dipropylene glycol-n-butyl ether) was used as the first plasticizer. CS-12 (JNC Corporation, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (Texanol)) was used as the second plasticizer. Dispatex SMAN (styrene maleic acid copolymer sodium salt: Nikka Chemical Co., Ltd.) was used as the dispersant. Other additives used as appropriate included preservatives, pH adjusters, antifreeze, thickeners, defoamers, rust inhibitors, compatibility aids, fungicides, antibacterial agents, and UV absorbers. The acrylic silicone resin used had a solid content of 50% by mass.

[0041] [Table 1]

[0042] (Other examples and comparative examples) Test plates for other examples and comparative examples were obtained in the same manner as in Example 1, except that the elongation rate of the undercoat film, the gloss value of the topcoat film, and the amounts of the first and second plasticizers were as shown in Tables 2 to 4 below. The amounts of plasticizers shown in Tables 2 to 4 below refer to parts by mass per 100 parts by mass of solids of the acrylic silicone resin composition. The gloss value of the topcoat film was adjusted by increasing or decreasing the amount of pigment contained.

[0043] [Table 2]

[0044] [Table 3]

[0045] [Table 4]

[0046] [Exterior evaluation] The topcoat paint compositions according to each example and comparative example were applied to a glass plate using a doctor blade (coating thickness 6 mil), and the plates were left to stand at room temperature for one day to obtain the topcoat film. The 60-degree specular gloss of the topcoat film was measured using a gloss meter (MULTI GLOSS 268A, manufactured by KONICA MINOLTA) in accordance with JIS K 5600-4-7:1999 specular gloss. Each measurement result was evaluated according to the following evaluation criteria. The measurement results and evaluation results are shown in Tables 2 to 4.

[0047] (Evaluation Criteria) 4:10 or less Under 3:20 2:20 over 40 or less Over 1:40

[0048] [Durability evaluation (undercoat conformability)] A slate board (15 cm long, 7 cm wide) was coated with a first primer paint (Nippon Paint Co., Ltd., product name: Nippe Water-Based Cation Sealer Transparent) using a medium-pile roller to obtain the first primer film. Next, a second water-based primer paint (product name: DAN Filler Epoxy, Nippon Paint Co., Ltd., Waterproof Multi-Layer Coating Material RE) was applied to the first primer film using a textured roller (standard grit), cured at room temperature for one day, and then the same primer paint was applied again, cured at room temperature for one day to obtain the second primer film. Finally, the topcoat paint composition according to each example and comparative example was applied twice with a medium-pile roller (13 mm), and cured at room temperature for seven days to form a multi-layer coating. The first and second coats of the topcoat paint composition were applied with a 3-hour interval between them. The sides and back of the slate board on which the above multi-layer coating was formed were sealed with a solvent-based two-component paint to create a test panel.

[0049] For the test plates described above, the plates were immersed in tap water at 20±2°C for 2 hours, and then immediately cooled in a constant temperature chamber at -20±2°C for 2 hours. This 4-hour cycle was repeated 100 times, after which the test plates were left to stand in the test chamber for 2 hours. Finally, the presence or absence of cracks and blisters in the coating was visually inspected. The inspection results were evaluated according to the following evaluation criteria. A score of 3 was considered a pass. The evaluation results are shown in Tables 2 to 4.

[0050] (Evaluation Criteria) 3: No cracks are observed. 2: Fine cracks are visible when examined with a magnifying glass. 1: Visible cracks are observed.

[0051] [Stain resistance evaluation] The low-stain properties of the topcoat film were evaluated by a rain streak stain test (bending exposure test). Specifically, a test plate for the rain streak stain test was prepared by painting the topcoat paint composition according to each example and comparative example onto an aluminum plate (200 mm × 100 mm × 0.8 mm) that was bent at a 60-degree angle approximately in the center. The test plate was set up with the area from the bottom edge to 10 cm being vertical and the area from 10 cm above the bottom edge being inclined, with the inclined side facing upwards, and was exposed to the outdoors. After outdoor exposure for approximately 3 months, the degree of soiling on the inclined side and the occurrence of rain streaks on the vertical side were visually checked, and the low-stain properties were evaluated according to the following four evaluation criteria. The evaluation results are shown in Tables 2 to 4. A score of 3 or higher was considered acceptable.

[0052] (Evaluation Criteria) 4: There was no dirt on the sloping surface and no rain streaks on the vertical surface. 3: There was slight dirt on the sloping surface and some rain streaks on the vertical surface. 2: There was dirt on the sloping surface and rain streaks on the vertical surface. 1: Dirt was clearly visible on the sloping surfaces, and rain streaks were noticeable on the vertical surfaces.

[0053] The results shown in Tables 2-4 confirm that the topcoat films in each example achieve both good conformability and stain resistance compared to the topcoat films in the comparative examples, and also provide a desirable appearance.

Claims

1. A water-based topcoat paint composition used to form a topcoat film on top of a primer film formed on the exterior wall of a building, having an elongation rate of 120% to 400%, The aforementioned topcoat paint composition comprises an acrylic silicone resin composition, a pigment, and a plasticizer. The plasticizer comprises a first plasticizer having a boiling point of 200°C or more and less than 250°C, and a second plasticizer having a boiling point of 250°C or more and less than 300°C. A topcoat paint composition wherein the total amount of the plasticizer is 10 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the solid content of the acrylic silicone resin composition.

2. The topcoat paint composition according to claim 1, wherein the mass ratio of the first plasticizer to the second plasticizer (first plasticizer / second plasticizer) is 4 / 1 to 1 / 2.

3. A multilayer coating comprising a primer coating film formed by a primer coating composition and a top coating film formed on the surface of the primer coating film by the top coating composition described in claim 1, The elongation rate of the aforementioned undercoat film is 120% or more and 400% or less. A multi-layer coating film having a 60-degree specular gloss of 20 or less on the surface of the topcoat film.

4. A method for repairing the exterior walls of a building, The process includes a step of applying the topcoat paint composition described in claim 1 to the surface of a primer coating film having an elongation rate of 120% or more and 400% or less to form a topcoat coating film, A repair method wherein the 60-degree specular gloss of the surface of the topcoat film is 20 or less.

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