Coating formation method

Abstract

To provide a method of forming a coating film which applies, to a base material, first and second coating materials satisfying specific conditions, thereby shortening the construction time, with each of the coating films having excellent adhesiveness.SOLUTION: The present invention provides a coating film forming method that applies a first coating material and a second coating material to a base material, the first coating material containing a polyol component having a hydroxyl value of 150 mgKOH / g or less (A1), an isocyanate component (B1), a curing accelerator (P1), and a powder component (C1), the second coating material containing a polyol component (A2) and an isocyanate component (B2).SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a novel method for forming a coating. [Background technology]

[0002] Traditionally, in buildings, civil engineering structures, etc., multi-layer finishes have been applied using coating materials such as primers, main coats, and topcoats to provide various functionalities for purposes such as protecting the structure and improving its aesthetics. Among these, two-component curing coating materials are widely used because they have excellent film properties and cure at room temperature.

[0003] However, depending on environmental conditions, two-component curing coatings may take a long time to cure. In particular, in the case of multi-layer finish coatings, the construction period may be prolonged because the coating film needs to be sufficiently dried and cured at each stage. In response to this, for example, Patent Document 1 describes a method in which a reaction accelerator is applied to the painted surface in advance, and then a two-component polyurethane coating is applied on top of it. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-276151 [Overview of the project] [Problems that the invention aims to solve]

[0005] Patent Document 1 describes a polyurethane coating material that reacts with a pre-applied reaction accelerator and hardens rapidly. However, it requires the separate preparation of the reaction accelerator solution in addition to the coating material used in multi-layer finish coatings, which may complicate the process. Furthermore, in some cases, sufficient adhesion cannot be obtained between the individual coatings, making it difficult to achieve improvements in the durability and aesthetics (finish) of the coatings. The present invention has been made in view of these problems, and aims to provide a coating formation method that can shorten the construction period and ensures that each coating has excellent adhesion. [Means for solving the problem]

[0006] To solve these problems, the inventors of the present invention have found that by applying a first coating material and a second coating material that satisfy specific conditions to a substrate, the construction period can be shortened, and each coating has excellent adhesion, thus completing the present invention.

[0007] In other words, the present invention has the following features. 1. A method for forming a coating by sequentially applying a first coating material and a second coating material to a substrate, The above-mentioned first coating material contains a polyol component (A1) with a hydroxyl value of 1 to 150 mgKOH / g or less, an isocyanate component (B1), a curing accelerator (P1), and a powder component (C1). The NCO / OH equivalent ratio of the above polyol component (A1) and the above isocyanate component (B1) is 0.6 to 3.5. The above-mentioned second coating material contains a polyol component (A2), an isocyanate component (B2), and a curing accelerator (P2) with a hydroxyl value of 1 to 1000 mgKOH / g or less. The NCO / OH equivalent ratio of the above polyol component (A2) and the above isocyanate component (B2) is 0.6 to 3.5. The weight ratio of the curing accelerator (P1w) content per 100 parts by weight of solids of the polyol component (A1) of the first coating material to the curing accelerator (P2w) content per 100 parts by weight of solids of the polyol component (A2) of the second coating material is (P1w) / (P2w) ≥ 5 A method for forming a coating, characterized by satisfying the following conditions. 2. The volume concentration of the powder component (C1) in the film formed from the first coating material is 30-90%. The volume concentration of the powder component (C2) in the film formed from the second coating material is less than 30%. The method for forming a coating as described in 1, characterized by the features described above. 3. The number-average molecular weight of the above polyol component (A1) is 3000 to 15000. The method for forming a film according to claim 1, characterized in that the number-average molecular weight of the polyol component (A2) is smaller than the number-average molecular weight of the polyol component (A1), and the difference between the number-average molecular weight of the polyol component (A1) and the number-average molecular weight of the polyol component (A2) is 2000 or more. [Effects of the Invention]

[0008] The present invention relates to a method for forming a film by applying a first coating material and a second coating material to a substrate, wherein both the first and second coating materials are coating materials containing a polyol component and an isocyanate component. In the present invention, by making a polyol component (A1) having a specific hydroxyl value an essential component of the first coating material, the construction period can be shortened and each coating can have excellent adhesion. [Modes for carrying out the invention]

[0009] The present invention will be described in detail below based on its embodiments.

[0010] The present invention relates to a method for forming a coating, characterized by sequentially applying a first coating material and a second coating material to a substrate. First, each component will be described.

[0011] <Base material> The substrates targeted by this invention include structures such as buildings and civil engineering structures, specifically various substrates such as walls, columns, floors, beams, roofs, stairs, ceilings, and doors. Examples of such substrates include concrete, mortar, siding boards, extruded boards, gypsum boards, perlite boards, bricks, plastics, wood, metals, steel frames (steel materials), glass, and porcelain tiles. These substrates may have a coating already formed on their surface, have undergone some kind of surface treatment (rust prevention treatment, flame retardant treatment, etc.), or have wallpaper attached. This invention is an optimal coating formation method for improving the heat resistance, protection, and aesthetics of steel frames (steel materials).

[0012] <First covering material> In the present invention, a first coating material is applied to the above substrate to form a first coating film. The first coating material contains, as essential components, a polyol component (A1), an isocyanate component (B1), a curing accelerator (P1), and a powder component (C1). The polyol component (A1) and the polyisocyanate component (B1) are components that react to form a coating film.

[0013] Examples of the polyol component (A1) include polyether polyol, polyester polyol, castor oil, castor oil-modified polyol, epoxy-modified polyol, silicone-modified polyol, fluorine-modified polyol, acrylic polyol, polycarbonate polyol, polylactone polyol, polybutadiene polyol, polypentadiene polyol, etc. One or more selected from these can be included. These polyols are preferably liquid at 20°C and can also be used in forms such as solvent-soluble type, non-aqueous dispersion (NAD) type, etc.

[0014] The hydroxyl value of the above polyol component (A1) is characterized by being 150 mgKOH / g or less (preferably 1 to 130 mgKOH / g, more preferably 3 to 100 mgKOH / g). By containing such a polyol component (A1), a coating film excellent in curability and adhesion can be formed. Further, the curing accelerator (P1) in the first coating layer can migrate to the second coating material and assist in the curing of the second coating material, and the curing time (tack-free drying time) of the second coating material can be shortened, so that the construction period can be shortened. The above action mechanism is not limited to the following, but it is considered that when the polyol component (A1) satisfies the above hydroxyl value, the formed coating film of the first coating material has an appropriate crosslink density, so that while ensuring curability and adhesion, the catalytic transferability to the second coating material is enhanced and the curing can be assisted. Here, the hydroxyl value referred to is a value (KOHmg / g) represented by the mg number of potassium hydroxide equimolar to the hydroxyl groups contained in 1 g of the solid content. Also, in the present invention, "α to β" is synonymous with "α or more and β or less".

[0015] In the present invention, it is preferable that the polyol component (A1) includes a polyether polyol (A1-1). Thereby, a film having even better adhesion can be formed. The polyether polyol (A1-1) is obtained, for example, by addition polymerization of polyhydric alcohols such as trimethylolpropane, glycerin, hexanetriol, pentaerythritol derivatives, sorbitol, neopentyl glycol, etc. and alkylene oxides such as ethylene oxide and propylene oxide. In the present invention, a polymer obtained by addition polymerization of the above polyhydric alcohols and ethylene oxide and / or propylene oxide is suitable, and those with ethylene oxide and / or propylene oxide added to the ends can also be used. Furthermore, as the above polyether polyol, it is preferable to include a polyether polyol having three or more functional groups (hydroxyl groups) having active hydrogen atoms (functional group number 3 or more). In this case, since the curability is excellent and a film can be formed stably, the effects of the present invention can be easily obtained. The functional group having an active hydrogen atom is preferably a hydroxyl group.

[0016] Such a polyether polyol (A1-1) preferably has a hydroxyl value of 1 to 150 mgKOH / g (more preferably 5 to 100 mgKOH / g, particularly preferably 10 to 50 mgKOH / g). Also, the above polyether polyol (A1-1) preferably has a molecular weight of 500 or more (more preferably 1000 to 20000, still more preferably 3000 to 18000, particularly preferably 5000 to 15000). In the present invention, the molecular weight of the polyol component is the number average molecular weight (Mn), which is the so-called polystyrene-equivalent molecular weight determined by gel permeation chromatography using a polystyrene polymer as a reference.

[0017] The content of the above polyether polyol (A1-1) is preferably 70% by weight or more (more preferably 80% by weight or more, and even more preferably 90% by weight or more) relative to the total amount of polyol component (A1). Alternatively, the above polyol component (A1) may consist solely of polyether polyol (A1-1), with an upper limit of preferably 100% by weight or less (more preferably 99.9% by weight or less, and even more preferably 99.5% by weight or less).

[0018] In this invention, in addition to the polyether polyol (A1-1) described above, other polyols (A1-2) can be used as the polyol component (A1) depending on the desired performance. For example, to improve the flame retardancy, fire resistance, and fireproofing properties of the coating, fluorine-modified polyols, epoxy-modified polyols, silicone-modified polyols, etc., can be used in combination. Furthermore, to improve adhesion, rust prevention, etc., polyester polyols, epoxy-modified polyols, acrylic polyols, etc., can be used in combination.

[0019] The content of the above polyol (A1-2) is preferably 0.1 to 30% by weight (more preferably 0.3 to 20% by weight, and even more preferably 0.5 to 10% by weight) in terms of solid content relative to the total amount of polyol component (A1). By satisfying this range, the desired performance can be imparted, and adhesion to the substrate and the second coating material is also favorable.

[0020] Examples of the polyisocyanate component (B1) include toluene diisocyanate (TDI), 4,4-diphenylmethane diisocyanate (pure-MDI), polymeric MDI, xylylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), hydrogenated XDI, hydrogenated MDI, etc., or derivatives obtained by allophanation, biuretation, dimerization (uretdioneation), trimerization (isocyanuration), adductation, carbodiimideation, etc., and blocked isocyanates obtained by blocking these with alcohols, phenols, ε-caprolactam, oximes, active methylene compounds, etc., and one or more selected from these can be used.

[0021] In the present invention, it is preferable that the polyisocyanate component (B1) contains hexamethylene diisocyanate (HMDI) and / or its derivatives (hereinafter also referred to as "HMDIs"). The content of the HMDIs is preferably 90% by weight or more (more preferably 95% by weight or more) of the total amount of the polyisocyanate component (B1). It is also preferable that the polyisocyanate component (B1) consists only of HMDIs. Furthermore, biuret derivatives and / or isocyanurate derivatives are preferred. In this case, a coating with excellent curability, adhesion, and finish can be formed.

[0022] The NCO content of the polyisocyanate component (B1) is preferably 10 to 35% by weight (more preferably 13 to 32% by weight, and even more preferably 15 to 30% by weight). In this case, a coating with excellent curability, adhesion, and finish can be formed.

[0023] The polyol component (A1) and the polyisocyanate component (B1) are mixed in a ratio such that the NCO / OH equivalent ratio of the polyol component (A1) and the polyisocyanate component (B1) is preferably 0.6 to 3.5 (more preferably 0.9 to 3.0). In this case, the curing properties are excellent, a uniform film of the desired thickness can be formed, and the finish and adhesion can be improved. Furthermore, the formed film has excellent durability (e.g., waterproofing, water resistance, crack resistance, substrate conformability, etc.) and can maintain its initial appearance (aesthetics) for a long period of time.

[0024] The curing accelerator (P1) is a substance that promotes the reaction between the polyol component (A1) and the polyisocyanate component (B1), and has the effect of accelerating the reaction of the isocyanate group to cure. Examples of curing accelerators (P1) include amine catalysts, organometallic catalysts, and inorganic catalysts. For example, amine catalysts include ethylenediamine, triethylenediamine, triethylamine, ethanolamine, diethanolamine, and hexamethylenediamine or their derivatives or mixtures with solvents. Examples of organometallic catalysts include organometallic compounds such as dibutyltin dilaurate and dibutyltin diacetate; and organometallic salts such as potassium acetate, zinc stearate, calcium stearate, lead stearate, aluminum stearate, and tin octoate. Examples of inorganic catalysts include tin chloride. These can be used individually or in combination of two or more, and can also be used in combination with a solvent. In the present invention, it is particularly preferable to include an organometallic catalyst. In this case, curing can be accelerated and the curability of the resin component can be improved, thereby enhancing the effects of the present invention.

[0025] The content of the curing accelerator (P1) is preferably 0.001 to 4 parts by weight (more preferably 0.005 to 3 parts by weight, and even more preferably 0.1 to 2 parts by weight) per 100 parts by weight of the polyol component (A1) (solid content). In this case, sufficient curability can be obtained, and the effects of the present invention can be enhanced. Furthermore, the content of (P1) is preferably adjusted according to the environment (temperature, etc.) during film formation. For example, in an environment of 20°C to 40°C, the polyol component is 0.005 to 1 part by weight, and even more preferably 0.01 to 0.5 parts by weight. Also, in an environment below 20°C (preferably -5°C to less than 20°C), the content is preferably 0.01 to 4 parts by weight (more preferably 0.05 to 3 parts by weight, and even more preferably 0.1 to 2 parts by weight) per 100 parts by weight of the polyol component (A1) (solid content). In such cases, for example, the pot life of the first coating material can be set to 2 hours or more (more preferably 4 hours or more, and even more preferably 6 hours or more). This improves the workability of the coating and further enhances the effects of the present invention.

[0026] The first coating material of the present invention contains a powder component (C1), and is formulated such that the volume concentration of the powder component (C1) in the formed film (hereinafter also referred to as "powder volume concentration (PVC)") is preferably 30-90% (more preferably 35-80%). With such a powder volume concentration (PVC), a coating film with sufficient adhesion can be formed. Furthermore, since the curing time (touch-dry time) can be shortened while ensuring sufficient workability, the construction period can be shortened. The above mechanism of action is not limited to the following, but since the first coating material of the present invention contains a large amount of powder component relative to the polyol component (A1), sufficient usable time and workability can be ensured even when an excess amount of curing accelerator (P1) is added. By applying the second coating material to such a first coating layer, the curing accelerator (P1) in the first coating layer migrates to the second coating material, and the curing of the second coating material can be assisted. This allows for sufficient working time for the second coating material while shortening its curing time (touch-dry time and hard-dry time). As a result, even with a shortened construction period, sufficient adhesion and excellent finish can be obtained.

[0027] The powder volume concentration (PVC) is the volume percentage of the powder component contained in the dried film, and is calculated from the weight parts and specific gravity of the resin component (components (A1) and (B1) above) and the powder component (C1) that constitute the coating material. The specific gravity of the resin component is assumed to be 1.

[0028] The powder component (C1) is not particularly limited, but examples include coloring pigments, extender pigments, and other functional powders.

[0029] As coloring pigments, chromatic pigments, white pigments, black pigments, etc., can be used. Of these, chromatic pigments are pigments that exhibit chromatic colors such as yellow, orange, red, green, blue, and purple. Examples of such chromatic pigments include inorganic ones such as ferric oxide, hydrated ferric oxide, ultramarine, cobalt blue, and cobalt green, and organic ones such as azo, naphthol, pyrazolone, anthraquinone, perylene, quinacridone, disazo, isoindolinone, benzimidazole, phthalocyanine, and quinophthalone. On the other hand, white pigments are pigments that exhibit white color, and examples include titanium dioxide, zinc oxide, and aluminum oxide. Black pigments are pigments that exhibit a black color, and examples include inorganic substances such as iron black, iron-manganese composite oxide, iron-copper-manganese composite oxide, iron-chromium-cobalt composite oxide, copper-chromium composite oxide, and copper-manganese-chromium composite oxide, as well as carbon black. These can be used individually or in combination of two or more. They may also be treated on their surface in some way. The average particle size of the coloring pigment is preferably 1 μm or less, more preferably 0.01 to 0.9 μm.

[0030] Examples of extender pigments (also called fillers) include heavy calcium carbonate, light calcium carbonate, talc, kaolin, clay, earthenware clay, china clay, silica, diatomaceous earth, silica sand, silica powder, quartz powder, hydrated fine silica powder, mica, barite powder, barium sulfate, precipitated barium sulfate, barium carbonate, magnesium carbonate, silica powder, and aluminum hydroxide. These can be used individually or in combination of two or more. The average particle size of the extender pigment is preferably 0.1 to 100 μm (preferably 1 to 80 μm).

[0031] Other functional powders may be used depending on the functionality of the coating. For example, to enhance the flame retardancy, fire prevention, and fire resistance of the coating, it is preferable to include one or more selected from foaming agents, carbonizing agents, flame retardants, fibers, etc. Such components can be those described in, for example, Japanese Patent Publication No. 2018-154808, Japanese Patent Publication No. 2019-65259, Japanese Patent Publication No. 2019-89996, Japanese Patent Publication No. 2019-183151, etc.

[0032] In addition to the above components, the first coating material of the present invention may also contain various other components, within a range that does not significantly impair the effects of the present invention. Examples of such components include wetting agents, plasticizers, curing retarders, lubricants, preservatives, fungicides, algaecides, antibacterial agents, thickeners, leveling agents, dispersants, defoamers, crosslinking agents, silane coupling agents, ultraviolet absorbers, light stabilizers, antioxidants, halogen scavengers, and diluent solvents.

[0033] The first coating material of the present invention is preferably a two-component coating material having a main component containing the polyol component (A1) and a curing agent containing the polyisocyanate component (B1). That is, the main component and the curing agent are stored in separate packages during distribution and can be mixed at the time of use (application). In this case, the powder component (C1) and the curing accelerator (P1) may be mixed into at least one of the main component and the curing agent, but in the present invention, it is preferable to mix them into the main component. Alternatively, a three-component type can be used in which each component is added when mixing the main component and the curing agent.

[0034] <Second covering material> In this invention, a second coating is formed by applying a second coating material to a first coating formed on the substrate surface. The second coating material enhances the durability and aesthetics of the first coating and can also impart various colors as needed. Such a second coating material contains a polyol component (A2) and a polyisocyanate component (B2) as essential components of the resin. The polyol component (A2) and the polyisocyanate component (B2) are components that react to form a coating.

[0035] Examples of polyol component (A2) include those similar to polyol component (A1) described above, and may include one or more selected from these.

[0036] The hydroxyl value of the polyol component (A2) is preferably 1 to 1000 mg KOH / g (more preferably 3 to 900 mg KOH / g). In this case, adhesion to the first coating is further improved, and durability, aesthetics, etc., can be enhanced.

[0037] In the present invention, it is preferable that the polyol component (A2) includes a polyether polyol (A2-1). The polyether polyol (A2-1) is the same as the polyether polyol (A1-1) described above, and one or more selected from these may be included.

[0038] The hydroxyl value of such polyether polyol (A2-1) is preferably 100 mg KOH / g or more (more preferably 150 to 1000 mg KOH / g, and even more preferably 200 to 800 mg KOH / g). Furthermore, the molecular weight of the polyether polyol (A2-1) is preferably 50 to 4000 (more preferably 100 to 2000, and even more preferably 150 to 1000). By using such a (A2-1) component, adhesion to the first film can be further improved, and durability, aesthetics, etc., can be enhanced.

[0039] Furthermore, it is preferable that the polyether polyol (A2-1) contains a polyol with a higher hydroxyl value than the polyether polyol (A1-1) described above. In the present invention, the difference in hydroxyl value between the polyether polyol (A1-1) and the polyether polyol (A2-1) is preferably 5 mg KOH / g or more (more preferably 10 mg KOH / g or more, even more preferably 50 mg KOH / g or more, particularly preferably 100 mg KOH / g or more, and most preferably 150 mg KOH / g or more). In such a case, adhesion to the first coating is further enhanced, and durability, aesthetics, etc., can be improved.

[0040] Furthermore, it is preferable that the polyether polyol (A2-1) contains a polyether polyol with a lower molecular weight than the polyether polyol (A1-1). That is, it is preferable that the first coating material contains a polyether polyol (A1-1) with a relatively higher molecular weight, and the second coating material contains a polyether polyol (A2-1) with a relatively lower molecular weight. The difference in molecular weight between the polyether polyol (A1-1) and the polyether polyol (A2-1) is preferably 2000 or more (more preferably 3000 or more, and even more preferably 4000 or more). This further enhances adhesion, durability, aesthetics, etc.

[0041] Furthermore, if either or both of the first and second coating materials contain multiple polyether polyols, it is sufficient that at least one polyether polyol (A1-1) of the first coating material and at least one polyether polyol (A2-1) of the second coating material satisfy the above conditions, and it is more preferable that all polyether polyols (A2-1) of the second coating material satisfy the above conditions for all polyether polyols (A1-1) of the first coating material.

[0042] Furthermore, the second coating material preferably contains acrylic polyol (A2-2) as the polyol component (A2). Acrylic polyol (A2-2) may be a polymer of (meth)acrylate alkyl ester, hydroxyl group-containing monomer, and other monomers as necessary. (meth)acrylate alkyl ester is a compound having a (meth)acryloyl group and an alkyl group. In this invention, alkyl acrylate and alkyl methacrylate are collectively referred to as (meth)acrylate alkyl ester. Monomer is a general term for compounds having polymerizable unsaturated double bonds.

[0043] Examples of such alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, t-pentyl (meth)acrylate, 1-ethylpropyl (meth)acrylate, 2-methylbutyl (meth)acrylate, and (meth) Examples include 3-methylbutyl acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, 2-methylpentyl (meth)acrylate, 4-methylpentyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, n-undecyl (meth)acrylate, and n-lauryl (meth)acrylate. These can be used individually or in combination of two or more.

[0044] Examples of the hydroxyl group-containing monomers mentioned above include hydroxyalkyl methacrylates such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, and 4-hydroxybutyl methacrylate. These can be used individually or in combination of two or more.

[0045] Examples of the above-mentioned other monomers include aromatic monomers, carboxyl group-containing monomers, amino group-containing monomers, pyridine monomers, nitrile group-containing monomers, amide group-containing monomers, epoxy group-containing monomers, carbonyl group-containing monomers, alkoxysilyl group-containing monomers, fluorine-containing monomers, ultraviolet-absorbing group-containing monomers, and photostable group-containing monomers. These can be used individually or in combination of two or more.

[0046] Furthermore, in the present invention, a polyester-containing acrylic polyol, which includes an acrylic polyol and a polyester, can also be used as component (A2-2). A polyester-containing acrylic polyol can be obtained, for example, by reacting a polyester resin having polymerizable unsaturated groups with an alkyl (meth)acrylate, a hydroxyl group-containing monomer, and other polymerizable monomers.

[0047] Polyester resins having polymerizable unsaturated groups can be obtained by partially using polybasic acids and / or polyhydric alcohols that have polymerizable unsaturated groups when condensing polybasic acids and / or polyhydric alcohols to produce polyester resins. Alternatively, polyester resins having polymerizable unsaturated groups can also be obtained by reacting a polyester resin with a monomer that can react with hydroxyl or carboxyl groups in the polyester resin, specifically maleic acid, (meth)acrylic acid, glycidyl (meth)acrylate, etc.

[0048] The hydroxyl value of the acrylic polyol (A2-2) is preferably 1 to 200 KOH mg / g (more preferably 3 to 100 KOH mg / g, and even more preferably 5 to 80 KOH mg / g). If the hydroxyl value of the acrylic polyol (A2-2) is within this range, an excellent adhesion improvement effect can be obtained. Furthermore, the weight ratio (solid content) of the polyether polyol (A2-1) to the acrylic polyol (A2-2) is preferably 90:10 to 10:90 (more preferably 80:20 to 20:80, and even more preferably 70:30 to 50:50). In this case, excellent adhesion to the first coating material is achieved, and excellent adhesion can also be exhibited when a film such as a finishing material is formed on the second coating material.

[0049] Furthermore, in the present invention, the total solid content of the polyether polyol (A2-1) and the acrylic polyol (A2-2) in the solid content of the polyol component (A2) is preferably 50% by weight or more (more preferably 80% by weight or more, and even more preferably 90% by weight or more). The upper limit is not particularly limited, and the invention may consist only of the polyether polyol (A2-1) and the acrylic polyol (A2-2). In such cases, the effects of the present invention can be fully demonstrated.

[0050] The polyisocyanate component (B2) in the second coating material is a component that undergoes a curing reaction with the polyol component (A2) described above. Examples of polyisocyanate (B2) include those similar to the polyisocyanate (B1) described above, and one or more selected from these may be included.

[0051] The mixing of component (A2) and component (B2) is carried out in a ratio such that the NCO / OH equivalent ratio of component (A2) to component (B2) is preferably 0.6 to 3.5 (more preferably 0.9 to 3.0). In this case, the curing properties are excellent, and the effects of the present invention can be fully demonstrated.

[0052] Furthermore, it is preferable that the second coating material contains a curing accelerator (P2) that promotes the reaction between the polyol component (A2) and the polyisocyanate component (B2). The curing accelerator (P2) of the second coating material may be the same as that of the curing accelerator (P1) described above, and may contain one or more selected from these. The curing accelerator (P1) and curing accelerator (P2) may be the same or different.

[0053] The content of the curing accelerator (P2) is preferably 0 to 3 parts by weight (more preferably 0.005 to 2 parts by weight, and even more preferably 0.01 to 0.5 parts by weight) per 100 parts by weight of the polyol component (A2) (solids). In this case, sufficient workability (pot life) and curability can be ensured, and the effects of the present invention can be enhanced. In the present invention, even in the embodiment in which the content of the curing accelerator (P2) is zero (not included), the reaction between the polyol component (A2) and the isocyanate component (B2) proceeds due to the action of the curing accelerator (P1), and a coating with excellent curability and adhesion can be formed. Furthermore, the content of (P2) is preferably adjusted according to the environment (temperature, etc.) during coating formation. For example, in an environment of 20°C to 40°C, it is preferably 0 to 2 parts by weight (more preferably 0.001 to 1 part by weight, and even more preferably 0.005 to 0.5 parts by weight) per 100 parts by weight of the polyol component (A2) (solids). Furthermore, in environments below 20°C (preferably between -5°C and 20°C), the amount of the second coating material is preferably 0 to 3 parts by weight (more preferably 0.005 to 2 parts by weight, and even more preferably 0.01 to 1 part by weight) per 100 parts by weight of the polyol component (A2) (solids). In such cases, for example, the pot life of the second coating material can be set to 2 hours or more (more preferably 4 hours or more, and even more preferably 6 hours or more). This improves the paintability and further enhances the effects of the present invention.

[0054] Furthermore, in the present invention, it is preferable that the content of curing accelerator (P1) per 100 parts by weight of polyol component (A1) (solid content) of the first coating material (P1w) and the content of curing accelerator (P2) per 100 parts by weight of polyol component (A2) (solid content) of the second coating material (P2w) satisfy the following formula [1]. This makes it possible to shorten the curing time (touch-dry time) while ensuring sufficient workability, thereby shortening the construction period. Equation [1]···(P1w) / (P2w)>1 (more preferably ≥5, even more preferably ≥10)

[0055] The above mechanism of action is not limited to the following, but since the first coating material of the present invention contains a large amount of powder component relative to the polyol component (A1), sufficient pot life and workability can be ensured even when the amount of curing accelerator (P1) is increased, and the curing accelerator (P1) can be retained in the first coating layer. By applying the second coating material to such a first coating layer, the curing accelerator (P1) in the first coating layer migrates to the second coating material, and the curing of the second coating material can be assisted. As a result, the curing time (touch-dry time) of the second coating material can be shortened while ensuring sufficient pot life for the second coating material. As a result, sufficient adhesion and excellent finish can be obtained even when the construction period is shortened.

[0056] The second coating material of the present invention preferably contains a powder component (C2). Furthermore, the volume concentration of the powder component (C2) in the formed film ("powder volume concentration (PVC)") is preferably less than 30% (more preferably 0-25%). With such a powder volume concentration (PVC), the curing accelerator (P1) in the first film layer can easily migrate to the second coating material, thereby assisting in the curing of the second coating material. This allows for a sufficient working time for the second coating material while shortening the curing time. As a result, even when the construction period is shortened, sufficient adhesion and excellent finish can be obtained.

[0057] The powder component (C2) may be the same as the powder component (C1) described above, and one or more selected from these may be included. In particular, the second coating material preferably contains a coloring pigment and / or an extender pigment. This increases the cohesive force during film formation, resulting in better adhesion and other effects. Furthermore, by including powder components with an average particle size of 1 μm or more (preferably 5 to 50 μm), adhesion and other effects can be further enhanced.

[0058] Furthermore, the second coating material may contain, to the extent that it does not significantly impair the effects of the present invention, the above-mentioned foaming agent, carbonizing agent, flame retardant, filler, fibers, etc., as a powder component (C2).

[0059] In addition to the above components, the second coating material of the present invention may also contain various other components, within a range that does not significantly impair the effects of the present invention. Examples of such components include wetting agents, plasticizers, curing retarders, lubricants, preservatives, fungicides, algaecides, antibacterial agents, thickeners, leveling agents, dispersants, defoamers, crosslinking agents, silane coupling agents, ultraviolet absorbers, light stabilizers, antioxidants, halogen scavengers, and diluent solvents.

[0060] The second coating material of the present invention can be prepared by mixing a main component containing a polyol component (A2) and a curing agent containing a polyisocyanate component (B2) immediately before painting, and then painting. In addition, in the present invention, a solvent can be mixed in as a diluent at the time of painting, separately from the main component and curing agent. The solvent can be included in either the main component, the curing agent, or both. The amount of diluent (solvent) mixed in is preferably such that the solid content of the second coating material after dilution is 25 to 90% by weight (more preferably 30 to 85% by weight). Within this range, the effects of the present invention can be fully demonstrated.

[0061] In the present invention, a topcoat can be applied as needed to protect the film formed by the above-mentioned coating materials (first coating material and second coating material). Any known topcoat can be used as such a topcoat. In the present invention, by having a second film formed by the second coating material, good adhesion to various topcoats can be obtained. Such topcoats can include, for example, clear or colored types, glossy or matte types, hard or elastic types, thin film types or thick film types. Furthermore, they may be water-based or solvent-based, and can be appropriately selected according to the desired purpose.

[0062] The topcoat material of the present invention preferably contains a resin component. Examples of such resins include solvent-soluble resins, non-aqueous dispersion resins, solvent-free resins, aqueous dispersion resins, and water-soluble resins. Examples of resin types include acrylic resins, urethane resins, epoxy resins, vinyl chloride resins, vinyl acetate resins, acrylic silicone resins, fluororesins, silicon resins, polyvinyl alcohols, cellulose derivatives, or composites thereof. These can be used individually or in combination of two or more. In particular, the present invention preferably contains one or more selected from urethane resins, epoxy resins, acrylic resins, acrylic silicone resins, and fluororesins.

[0063] Furthermore, the above resin component may also have crosslinking reactivity. When the resin component is a crosslinking-type resin, the water resistance, durability, and adhesion of the formed film are enhanced, and the occurrence of blistering and peeling of the film due to rain, condensation, etc., can be suppressed. In addition, the heat-resistant protective properties of the first coating material can be stably maintained. Such a crosslinking-type resin may be one that undergoes a crosslinking reaction on its own, or one that undergoes a crosslinking reaction by being mixed separately with a crosslinking agent. Such crosslinking reactivity can be imparted by combining reactive functional groups such as hydroxyl groups and isocyanate groups, carbonyl groups and hydrazide groups, epoxy groups and amino groups, aldo groups and semicarbazide groups, keto groups and semicarbazide groups, alkoxyl groups with each other, carboxyl groups and metal ions, carboxyl groups and carbodiimide groups, carboxyl groups and epoxy groups, carboxyl groups and aziridine groups, carboxyl groups and oxazoline groups, etc. Among these, it is preferable to include a crosslinking-type resin that undergoes one or more crosslinking reactions selected from hydroxyl groups and isocyato groups, carbonyl groups and hydrazide groups, and epoxy groups and amino groups.

[0064] In addition to the resin component of the above-mentioned topcoat, other components such as coloring pigments, extender pigments, and aggregates can be mixed in. By appropriately incorporating such components, desired colors and textures can be achieved. The amount of coloring pigments, extender pigments, aggregates, etc. mixed in is not particularly limited as long as it does not hinder the effects of the above-mentioned coating material (foaming properties, heat protection properties, etc.), but preferably it is 1 to 2000 parts by weight (more preferably 5 to 1000 parts by weight) per 100 parts by weight of solid content of the resin component.

[0065] In this invention, it is particularly preferable to use pigments having infrared reflectivity and / or infrared transmittance as the coloring pigment and extender pigment. This further enhances effects such as heat resistance protection.

[0066] Examples of pigments that have infrared reflectivity include aluminum flakes, titanium dioxide, barium sulfate, zinc oxide, iron oxide, calcium carbonate, silicon dioxide, magnesium oxide, zirconium oxide, yttrium oxide, indium oxide, alumina, iron-chromium composite oxide, manganese-bismuth composite oxide, manganese-yttrium composite oxide, black iron oxide, iron-manganese composite oxide, iron-copper-manganese composite oxide, iron-chromium-cobalt composite oxide, copper-chromium composite oxide, copper-manganese-chromium composite oxide, etc., and one or more of these can be used.

[0067] Examples of pigments that transmit infrared light include perylene pigments, azo pigments, lead yellow, titanium red, cadmium red, quinacridone red, isoindolinone, benzimidazolone, phthalocyanine green, phthalocyanine blue, cobalt blue, induthlene blue, ultramarine, and Prussian blue. One or more of these can be used.

[0068] Furthermore, the topcoat material can also contain various additives that are normally used in paints. Examples of such additives include thickeners, film-forming aids, leveling agents, wetting agents, plasticizers, antifreeze agents, pH adjusters, preservatives, antifungal agents, antialgal agents, antibacterial agents, dispersants, defoamers, adsorbents, UV absorbers, light stabilizers, antioxidants, fibers, destaining agents, hydrophilic agents, water repellents, coupling agents, catalysts, and the like.

[0069] <Film formation method> The present invention relates to a method for forming a coating, characterized by applying a first coating material and a second coating material to a substrate. Specifically, (1) A step of applying a first coating material to a substrate to form a first coating layer, (2) A step of applying a second coating material onto the first coating to form a second coating layer. This includes, as needed, (3) A step of applying a top coat material onto the second film described above to form a top coat layer. It can also include.

[0070] In step (1) above, when applying the coating material to the substrate, it can be applied using, for example, a brush, roller, spray (air spray, airless spray), or an application tool such as a trowel. The amount applied and the number of coats of the first coating material should be set according to the functionality of the various coating materials.

[0071] For example, if the first coating material contains a foaming agent, carbonizing agent, etc., as a powder component (C1), it is sufficient to apply it in one to several layers, preferably so that the dry film thickness per layer is 400 μm or more (more preferably 500 to 5000 μm). The final film thickness can be set appropriately depending on the desired functionality, application area, etc., but is preferably about 0.4 to 10 mm. In this case, the amount of the first coating material applied during painting is preferably 0.4 to 20.0 kg / m². 2 (More preferably 0.6~17.0 kg / m 2 It is within the range of ).

[0072] Furthermore, the first coating material of the present invention has excellent curability because it forms a film through the reaction of component (A1) and component (B1). Drying is preferably carried out at 0 to 40°C, and the interval to the next step (step (2) above) is preferably 5 hours or more (more preferably 10 hours or more and within 30 days). Also, steps (1) and (2) above may be carried out in different locations. For example, step (1) above can be carried out in advance in a factory or the like (pre-coating), then the substrate can be transported to the installation location, and then step (2) above can be carried out.

[0073] In step (2) above, the second coating material can be applied using various methods such as brush painting, roller painting, or spray painting. The amount of the second coating material applied is preferably 30 to 500 g / m². 2 (comfortably 50-300g / m 2 The number of coats of the second coating material can be set appropriately depending on the surface condition of the first coating material, but preferably it is 1 to 2 times. Furthermore, the coating material of the present invention can fully exhibit its effects even with only one coat.

[0074] The drying of the second coating material is preferably carried out at 0 to 40°C, and the next step (step (3) above) can be performed after the second coating material is touch dry. The interval between these steps is preferably 2 hours or more (more preferably 3 hours or more and within 30 days). In addition, according to the coating formation method of the present invention, the curability of the second coating material is excellent, so the interval between this step and the next step (step (3) above) can be set to be shorter. Furthermore, steps (1), (2), and (3) above may be carried out in different locations. For example, step (1) above can be carried out in advance in a factory or the like (pre-coating), then the substrate can be transported to the installation location, and then steps (2) and (3) above can be carried out, or steps (1) and (2) above can be carried out in advance in a factory or the like (pre-coating), then the substrate can be transported to the installation location, and then step (3) above can be carried out.

[0075] In step (3) above, the topcoat material can be applied using various methods such as brush painting, roller painting, or spray painting. The application amount is preferably 30 to 5000 g / m². 2 (comfortably 50-3000g / m 2 The number of coats of the finishing material can be set as appropriate, but preferably 1 to 2 coats. Drying is preferably carried out at room temperature.

[0076] <Structure> According to the present invention, a structure can be obtained having a first coating formed by the first coating material and a second coating formed by the second coating material on a substrate. The structure of the present invention has excellent adhesion and durability. Furthermore, by having a topcoat layer formed by a topcoat material on the second coating, the structure of the present invention can have even better adhesion, and further improve aesthetics, weather resistance, etc. [Examples]

[0077] The following examples illustrate the features of the present invention. However, the present invention is not limited to these examples.

[0078] The following ingredients were used: [Polyol component (A)] • Polyol 1: Polyether polyol [Hydroxyl value (solids) 24 mg KOH / g, number of functional groups 3, number average molecular weight 7000, solids content 100% by weight] • Polyol 2: Polyether polyol [Hydroxyl value (solids) 33 mg KOH / g, number of functional groups 3, number average molecular weight 5100, solids content 100% by weight] • Polyol 3: Polyether polyol [Hydroxyl value (solids) 55 mg KOH / g, number of functional groups 3, number average molecular weight 3000, solids content 100% by weight] • Polyol 4: Polyether polyol [Hydroxyl value (solids) 160 mg KOH / g, number of functional groups 3, number average molecular weight 1000, solids content 100% by weight] • Polyol 5: Polyether polyol [Hydroxyl value (solids) 400 mg KOH / g, number of functional groups 3, number average molecular weight 400, solids content 100 wt%] • Polyol 6: Acrylic polyol [Hydroxyl value (solids) 40KOH mg / g, solids content 50% by weight, medium: aromatic hydrocarbon compound, ester compound] Note that all of the above components (A) are liquid at 20°C.

[0079] [Polyisocyanate component (B)] • Isocyanate 1: Biuret-type hexamethylene diisocyanate (NCO content 23.5%)

[0080] [Powder component (C)] • Coloring pigment: Titanium dioxide (specific gravity 4.2) • Extender pigment: Heavy calcium carbonate (specific gravity 2.7) • Functional powder 1: Melamine (specific gravity 1.57) • Functional powder 2: Pentaerythritol (specific gravity 1.55) • Functional powder 3: Ammonium polyphosphate (specific gravity 1.9) [Curing accelerator (P)] • Curing accelerator: Organometallic (tin) catalyst • Additive 1: Dispersant, defoamer, etc. • Additive 2: Diluting solvent (aromatic hydrocarbon)

[0081] (Preparation of the first coating material) According to the formulations shown in Table 1, components (A1), (C1), (P1), and additives 1 and 2 were mixed by conventional methods to prepare the main component. Next, component (B) was mixed in as a curing agent to obtain the first coating materials 1 to 6. The amount of component (P1) P1w is shown in Tables 3 and 4.

[0082] [Table 1]

[0083] (Preparation of the second coating material) According to the formulations shown in Table 2, components (A2), (C2), (P2), and additives 1 and 2 were mixed by conventional methods to prepare the main component. Next, component (B2) was mixed in as a curing agent to obtain second coating materials 1 to 3. The amount of component (P2) P2w is shown in Tables 3 and 4.

[0084] [Table 2]

[0085] (Preparation of topcoat material) A main component was prepared by uniformly mixing and stirring 100 parts by weight of acrylic polyol (hydroxyl value 20 KOH mg / g, solids content 50% by weight, medium: aliphatic hydrocarbon compound), 40 parts by weight of titanium dioxide, and 10 parts by weight of additives (thickener, defoamer) using a conventional method. Next, a curing agent was prepared by mixing 50 parts by weight of polyisocyanate (adduct-type hexamethylene diisocyanate, NCO content 12%) and 50 parts by weight of diluent solvent (aliphatic hydrocarbon). The main component and the curing agent were mixed so that the NCO / OH equivalent ratio of the polyol component and the polyisocyanate component was 1.0, and these mixtures were used as the topcoat material.

[0086] (Examples 1-14, Comparative Examples 1 and 2) The following evaluations were conducted for each coating material. The combinations of the first and second coating materials, and the proportions of components (P1) and (P2) are shown in Tables 3 and 4. Furthermore, all painting and curing processes described below were performed at a temperature of 25°C (relative humidity 50%).

[0087] <Hardening evaluation> A 150mm x 70mm steel plate is coated with 1.5 kg / m² of the first covering material. 2 The coating was spray-applied and cured for 24 hours. Then, the second coating material was applied at a rate of 100g / m². 2 The material was applied with a brush, and the time required to reach touch-dry and hard-dry states as specified in JIS K5400 was evaluated. (Dry to the touch) A: Less than 4 hours B: 4 hours or more but less than 6 hours C: 6 hours or more but less than 10 hours D: More than 10 hours (Hardening and Drying) A: Less than 24 hours B: 24 hours or more and less than 36 hours C: 36 hours or more and less than 48 hours D: 48 hours or more

[0088] <Adhesion Evaluation 1> On a 150 mm × 70 mm steel plate, the first coating material was spray-coated at 1.5 Kg / m 2 and cured for 7 days. Then, the second coating material was brush-coated at an application rate of 100 g / m 2 and cured for 24 hours to prepare Specimen [I].

[0089] <Adhesion Evaluation 1> For the prepared Specimen [I], the adhesion to the surface of the plasticizer-containing material was evaluated by the cross-cut tape method according to JIS K 5600-5-6. The evaluation criteria are as follows. A: The area of the defective part is less than 10% B: The area of the defective part is 10% or more and less than 25% C: The area of the defective part is 25% or more and less than 50% D: The area of the defective part is 50% or more

[0090] <Adhesion Evaluation 2> On a 150 mm × 70 mm steel plate, the first coating material was spray-coated at 1.5 Kg / m 2 and cured for 7 days. Then, the second coating material was brush-coated at an application rate of 100 g / m 2 and cured for 24 hours. Next, the topcoat material was spray-painted at an application rate of 0.3 kg / m 2 and cured for 72 hours to prepare Specimen [II]. For the prepared Specimen [II], the adhesion to the coating material and the topcoat material was evaluated by the cross-cut tape method according to JIS K 5600-5-6. The evaluation criteria are the same as those in Adhesion Evaluation 1 above.

[0091] <Adhesion Evaluation 3> On a 150 mm × 70 mm steel plate, the first coating material was spray-coated at 1.5 Kg / m 2The coating was spray-applied and cured for 24 hours. Then, the second coating material was applied at a rate of 100g / m². 2 It was then brushed on and allowed to cure for 3 hours. Next, topcoat material 1 was applied at a rate of 0.3 kg / m². 2 Test specimens [III] were prepared by spray painting and curing for 72 hours. The adhesion between the prepared test specimens [III] and the covering material and topcoat material was evaluated using the grid tape method in accordance with JIS K 5600-5-6. The evaluation criteria were the same as those for adhesion evaluation 1 above.

[0092] <Finishing Quality Evaluation> The finish quality of the test specimens [III] was visually evaluated. A scale of 4 was used, with "A" indicating excellent finish quality and "D" indicating abnormal finish quality (Excellent: A > B > C > D: Poor).

[0093] [Table 3]

[0094] [Table 4]

Claims

1. A method for forming a coating by sequentially applying a first coating material and a second coating material to a substrate, The above-mentioned first coating material comprises a polyol component (A1) with a hydroxyl value of 1 to 150 mgKOH / g or less, an isocyanate component (B1), a curing accelerator (P1), and a powder component (C1). The NCO / OH equivalent ratio of the above polyol component (A1) and the above isocyanate component (B1) is 0.6 to 3.

5. The above-mentioned second coating material contains a polyol component (A2) having a hydroxyl value of 1 to 1000 mgKOH / g or less, an isocyanate component (B2), and a curing accelerator (P2). The NCO / OH equivalent ratio of the above polyol component (A2) and the above isocyanate component (B2) is 0.6 to 3.

5. The weight ratio of the curing accelerator (P1w) content (P1w) per 100 parts by weight of solids of the polyol component (A1) of the first coating material to the curing accelerator (P2w) content (P2w) per 100 parts by weight of solids of the polyol component (A2) of the second coating material is (P1w) / (P2w) ≥ 5 A method for forming a coating, characterized by satisfying the following conditions.

2. The volume concentration of the powder component (C1) in the film formed from the first coating material is 30 to 90%. The volume concentration of the powder component (C2) in the film formed from the second coating material is less than 30%. The method for forming a coating according to feature 1.

3. The number-average molecular weight of the above polyol component (A1) is 3000 to 15000. The method for forming a film according to claim 1, characterized in that the number average molecular weight of the polyol component (A2) is smaller than the number average molecular weight of the polyol component (A1), and the difference between the number average molecular weight of the polyol component (A1) and the number average molecular weight of the polyol component (A2) is 2000 or more.

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