Method for repairing the coating

Abstract

This invention provides an efficient method for repairing heat-resistant protective coatings, reducing the time and effort required. [Solution] A method for repairing a heat-resistant protective coating, characterized by including the steps of: fitting a heat-resistant protective sheet into a recess in the coating to be repaired so that it protrudes more than the coating; heating and pressing the heat-resistant protective sheet to smooth it out; and covering the boundary of the recess.

Description

Technical Field

[0001] The present invention relates to a method for repairing a novel coating film.

Background Art

[0002] Conventionally, for the purpose of protecting base materials such as steel materials, concrete, wood, synthetic resins, etc. from fire, various coating materials that foam due to a temperature rise during a fire or the like and form a carbonized heat-insulating layer have been proposed. As such a coating material, a material obtained by blending a heat-resistant-imparting powder or the like into a synthetic resin is known. Such a coating material is applied to the surface of the base material to be protected to form a coating film having heat-resistant protection properties. Further, on the surface of such a coating film, a decorative coating film or the like may be provided for the purpose of improving aesthetics or the like.

[0003] However, in the coating film as described above, when defects such as swelling, peeling, cracking, chipping, etc. occur due to various conditions (construction conditions, environmental conditions, etc.) during or after film formation, or physical damage, etc., it is necessary to repair the coating film. For example, Patent Document 1 describes a specific repair method using an undercoat paint, a thermally foaming paint, or the like.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the repair method as described in the above patent document, it is necessary to repeatedly apply a thermally foaming paint a plurality of times to the concave portion of the coating film to be repaired, and a certain amount of labor and time are required until the repair is completed.

[0006] This invention has been made in view of these points, and aims to provide an efficient method that can reduce the effort and time required when repairing a heat-resistant protective coating. [Means for solving the problem]

[0007] To solve these problems, the inventors, after diligent research, conceived of a specific repair method using a heat-resistant protective sheet, and thus completed the present invention.

[0008] In other words, the present invention has the following features. 1. A method for repairing a heat-resistant protective coating, (1) A step of fitting a heat-resistant protective sheet into the recess of the above-mentioned coating that needs to be repaired, so that it protrudes more than the coating. (2) The process of heating and pressing the heat-resistant protective sheet to make it even, and covering the boundary of the recess, Includes, The above-mentioned heat-resistant protective sheet is characterized by containing a thermoplastic resin with a melting point of 105°C or lower, and a heat-resistant powder, as a method for repairing a coating. 2. The method for repairing a coating according to 1, characterized in that the heat-resistant protective sheet is thicker than the thickness of the coating. 3. The method for repairing a coating according to 1, characterized in that the thickness of the heat-resistant protective sheet is 1.1 times or more and 2 times or less the thickness of the coating. 4. The method for repairing a coating according to 1, characterized in that, in step (1) above, a heat-resistant protective sheet is brought into contact with and fitted into the recessed end. [Effects of the Invention]

[0009] According to the present invention, the time and effort required for repairing a heat-resistant protective coating can be reduced, and repairs can be carried out efficiently. [Brief explanation of the drawing]

[0010] [Figure 1]FIG. 1 is a cross-sectional view for explaining an embodiment of a method for repairing a coating according to the present invention, (a) is before repair, (b) is after step (1), and (c) is after step (2). [Figure 2] FIG. 2 is a front view for explaining an embodiment of a method for repairing a coating according to the present invention, (a) is before repair, (b) is after step (1), and (c) is after step (2). [Figure 3] FIG. 3 is a cross-sectional view for explaining an embodiment of a method for repairing a coating according to the present invention, (a') is before repair, (b) is after step (1), and (c) is after step (2). [Figure 4] FIG. 4 is a cross-sectional view for explaining an embodiment of a method for repairing a coating according to the present invention, (a') is before repair, (b) is after step (1), and (c) is after step (2).

Description of Reference Numerals

[0011] 1. Substrate 2. Coating having heat-resistant protection 3. Recess 31. Recess boundary portion​​​​​​​​​​​​​​​​​​​​​​​​The coating targeted by the repair method of the present invention has heat-resistant protection. Specifically, it has the performance of protecting the base material from high heat such as in a fire. Such a coating foams (preferably when the surface temperature of the coating reaches 200°C or higher, more preferably 250°C or higher) due to the temperature rise during a fire or the like, forming a carbonized heat-insulating layer to protect the base material from high heat.

[0015] Examples of the base material include various base materials that constitute various parts such as walls, columns, floors, beams, roofs, stairs, ceilings, and doors. Examples of the materials that make up such base materials include steel materials, metals, concrete, mortar, siding boards, tiles, bricks, glass, wood, synthetic resins, plastics, rubber, and the like. These base materials may have a coating (rust-proof coating, primer coating, topcoat, etc.) already formed on their surfaces, or may have been subjected to some base treatment (rust-proof treatment, flame-retardant treatment, etc.).

[0016] Examples of the coating with heat-resistant protection (hereinafter simply referred to as "coating") include those formed by a coating material (such as a thermally expandable paint) containing a resin and heat-resistant imparting powders such as a foaming agent, a carbonizing agent, a flame retardant, and a filler.

[0017] Examples of the resin include acrylic resin, vinyl acetate resin, vinyl acetate-acrylic copolymer resin, polyethylene resin, acrylic-styrene copolymer resin, vinyl acetate-ethylene copolymer resin, polyester resin, vinyl acetate-versatic acid vinyl ester copolymer resin, vinyl acetate-versatic acid vinyl ester-acrylic copolymer resin, phenol resin, petroleum resin, vinyl chloride resin, epoxy resin, urethane resin, polybutadiene resin, alkyd resin, melamine resin, fluororesin, propylene rubber, chloroprene rubber, butyl rubber, isobutylene rubber, and the like. These can be used alone or in combination of two or more.

[0018] Examples of foaming agents include expandable graphite; melamine and its derivatives; dicyandiamide and its derivatives; azodicarbonamide; urea; thiourea; and other nitrogen-containing foaming agents. These can be used individually or in combination of two or more. Such foaming agents can impart a foaming effect to the coating due to temperature increases such as during a fire, and specifically, they can impart a foaming effect when the temperature of the coating surface preferably reaches 200°C or higher.

[0019] Examples of carbonizing agents include pentaerythritol, dipentaerythritol, trimethylolpropane, starch, and casein. These can be used individually or in combination of two or more. Such carbonizing agents can impart the effect of forming a carbonized insulating layer by carbonizing and dehydrating the resin when the temperature rises, such as during a fire.

[0020] Examples of flame retardants include organophosphorus compounds such as tricresyl phosphate and diphenylcresyl phosphate; chlorine compounds such as chlorinated polyphenyls, chlorinated polyethylenes, diphenyl chloride, triphenyl chloride, chlorinated paraffins, pentachloride fatty acid esters, perchloropentacyclodecane, chlorinated naphthalene, and tetrachlorophthalic anhydride; antimony compounds such as antimony trioxide and antimony pentachloride; phosphorus compounds such as phosphorus trichloride, phosphorus pentachloride, ammonium phosphate, ammonium polyphosphate, melamine phosphate, melamine polyphosphate, melamine polyphosphate, melamine polyphosphate, boron phosphate, boron polyphosphate, aluminum phosphate, and aluminum polyphosphate; and other inorganic compounds such as zinc borate and sodium borate. These can be used individually or in combination of two or more. Such flame retardants exhibit at least one effect, such as dehydration cooling, non-combustible gas generation, and carbonization promotion, under high-temperature conditions such as during a fire, thereby suppressing the combustion of resins.

[0021] Examples of fillers include carbonates such as calcium carbonate, sodium carbonate, magnesium carbonate, and aluminum oxide; metal oxides such as titanium dioxide and zinc oxide; and inorganic powders such as silica, clay, talc, kaolin, diatomaceous earth, shirasu, mica, wollastonite, silica sand, silica, quartz, vermiculite, alumina, and fly ash. These can be used individually or in combination of two or more. Such fillers can exhibit effects such as improving the strength of the carbonized insulation layer.

[0022] The coating material that forms a heat-resistant protective film may also contain, in addition to the above components, pigments, fibers, wetting agents, plasticizers, lubricants, preservatives, antifungal agents, antialgal agents, antibacterial agents, thickeners, leveling agents, dispersants, defoaming agents, crosslinking agents, ultraviolet absorbers, antioxidants, diluent solvents, and the like.

[0023] The thickness of the coating formed by such a coating material can be appropriately set depending on the desired functionality, application area, etc., but is preferably about 0.4 to 15 mm. In this invention, "a to b" is synonymous with "a or more and b or less".

[0024] A heat-resistant protective coating may have a decorative coating on its surface for purposes such as improving aesthetics or durability. Such a decorative coating can be formed by applying a known topcoat material. Examples of topcoats include acrylic resin-based, urethane resin-based, acrylic silicone resin-based, and fluororesin-based topcoats.

[0025] The present invention provides a method for repairing a coating when defects (e.g., blistering, lifting, cracking, chipping, etc.) occur in the aforementioned coating. For example, in the case of defects such as blistering or lifting, it is desirable to partially remove the coating in the defective area and its vicinity before repair. This creates a recess to be repaired (hereinafter also simply referred to as "recess"). In the case of defects such as cracking, chipping, etc., a recess is often formed at the time the defect occurs, but the shape of the recess can also be adjusted by partially removing the coating in the vicinity of the defective area. In the present invention, it is preferable to partially remove the coating in the defective area and its vicinity of the heat-resistant protective coating and adjust it to the desired recess shape.

[0026] The shape of the recess to be repaired (the shape of the coating when viewed from the front) is not particularly limited and may be irregular in shape. However, if it is shaped like a circle, ellipse, triangle, square, strip, or a shape similar to these, work efficiency can be improved. The size of such a recess (the length of the coating when viewed from the front) is preferably 5 to 800 mm, more preferably 8 to 500 mm, and even more preferably 10 to 300 mm. The depth of the recess can be set appropriately according to the defect in the coating, but is preferably 0.3 to 15 mm, more preferably 0.4 to 10 mm, and even more preferably 0.5 to 6 mm. The depth of the recess can also be the same as the thickness of the coating. In this invention, when the recess of the coating to be repaired is large (large area) (for example, 500 mm) 2 Above, or 800mm 2 Above, or 1300mm 2 Even in the above cases, repairs can be carried out efficiently and simply while maintaining the heat-resistant protective performance of the heat-resistant coating. The upper limit of the size of the recess is preferably 2500 cm². 2 More specifically, 2025cm 2 The following applies. In such cases, repairs can be carried out efficiently.

[0027] In this invention, such recesses are repaired using a heat-resistant protective sheet. The heat-resistant protective sheet used contains a thermoplastic resin with a melting point of 105°C or lower, and a heat-resistant powder.

[0028] The thermoplastic resin has a melting temperature of 105°C or lower, preferably 100°C or lower, and more preferably 90°C or lower. If the melting temperature exceeds the above value, it is necessary to perform the pressing operation at a relatively high temperature. Furthermore, the melting temperature of the thermoplastic resin is preferably 50°C or higher, and more preferably 60°C or higher. The melting temperature is the value measured by the method described in JIS K6924-2 (using a DSC (differential scanning calorimetry)).

[0029] Various resins that satisfy the above melting temperature can be used as the thermoplastic resin. Examples of such thermoplastic resins include polyester resin, polybutadiene resin, acrylic resin, styrene resin, acrylic styrene resin, vinyl acetate resin, ethylene vinyl acetate resin, vinyl acetate-versatic acid vinyl ester resin, vinyl acetate-versatic acid vinyl ester-acrylic resin, vinyl acetate-acrylic resin, urethane resin, alkyd resin, fluororesin, polyethylene resin, vinyl chloride resin, polypropylene resin, polystyrene resin, etc. These can be used individually or in combination of two or more. Preferably, the thermoplastic resin is one or more selected from acrylic resin, styrene resin, acrylic styrene resin (acrylic-styrene copolymer resin), vinyl acetate resin, and ethylene vinyl acetate resin (ethylene-vinyl acetate copolymer resin), and a configuration containing at least ethylene vinyl acetate resin is more preferable.

[0030] Examples of heat-resistant powders include one or more selected from foaming agents, carbonizing agents, flame retardants, and fillers. The foaming agents, carbonizing agents, flame retardants, and fillers can be the same as those used in the aforementioned heat-resistant protective coating. Such heat-resistant powders preferably include foaming agents, carbonizing agents, flame retardants, and fillers. The heat-resistant protective sheet of the present invention preferably foams up and forms a carbonized heat insulating layer when the temperature rises due to a fire or other event (preferably when the surface temperature of the heat-resistant protective sheet reaches 200°C or higher, and more preferably 250°C or higher).

[0031] The ratio of heat-resistant powder in the heat-resistant protective sheet is 200 to 1000 parts by mass, preferably 250 to 900 parts by mass, and more preferably 300 to 800 parts by mass, per 100 parts by weight of the thermoplastic resin. The lower limit of the ratio of heat-resistant powder is set to the above value, making it easy to directly press the heat-resistant protective sheet using a pressing tool when pressing the sheet, and ensuring sufficient adhesion and finish. The upper limit of the ratio of heat-resistant powder is set to the above value, making it easy to fit the sheet into recesses that need to be repaired, and ensuring sufficient adhesion and finish.

[0032] To obtain a heat-resistant protective sheet, the mixture obtained by uniformly mixing the above-mentioned components can be molded by a known method. After molding into a sheet, it can be processed into a desired shape (for example, by cutting with a cutter). When mixing the components, solvents can be added or heating can be performed as needed.

[0033] Various additives can be mixed into the above mixture. Examples of additives include pigments, fibers, wetting agents, plasticizers, lubricants, preservatives, fungicides, algaecides, antibacterial agents, thickeners, leveling agents, dispersants, defoamers, crosslinking agents, UV absorbers, antioxidants, and catalysts.

[0034] Examples of molding methods include pouring the mixture into a mold and demolding after drying; applying the mixture to release paper using a heated coating machine and then winding it up; forming a sheet from a mixture kneaded with a kneader or the like using an extrusion molding machine; supplying a mixture kneaded with a kneader or the like between two rolls and forming it into a sheet; forming a sheet from a mixture pelletized and then forming it into a sheet using an extrusion molding machine; and rolling a mixture kneaded with a Banbury mixer or mixing rolls using a calender consisting of multiple hot rolls to form a sheet.

[0035] The thickness of the heat-resistant protective sheet is preferably 0.4 to 20 mm, more preferably 0.5 to 15 mm, and even more preferably about 0.7 to 10 mm. The thickness of the heat-resistant protective sheet can be set within the above range according to the depth of the recess to be repaired. In this case, one heat-resistant protective sheet of a thickness corresponding to the depth of the recess can be used, or two or more sheets can be layered to achieve a thickness corresponding to the depth of the recess. In such cases, repairs can be carried out efficiently. Furthermore, it is preferable that the heat-resistant protective sheet used in this invention is flexible. This makes it easier to fit into the recess to be repaired and to make contact with the edges of the recess, thereby further enhancing the effects of this invention.

[0036] The heat-resistant protective sheet of the present invention may consist only of a sheet containing the above-mentioned components, but it is preferable that a fibrous sheet is laminated on the back surface. This makes it easier to mold to the shape of the recess to be repaired and to easily fit into the recess, thus enabling efficient repair. Furthermore, when the heat-resistant protective sheet foams up due to a temperature rise such as during a fire and forms a carbonized insulation layer, the effect of preventing the formed carbonized insulation layer from falling off is enhanced, and stable heat-resistant protection can be maintained. In particular, when the recess of the film to be repaired is large, for example 500 mm 2 In the case of such a large area, the above-mentioned effect allows for efficient repair, which is advantageous.

[0037] Examples of such fibrous sheets include sheets containing organic fibers and / or inorganic fibers, such as woven or nonwoven fabrics, meshes, etc. Examples of organic fibers include pulp fibers, polyester fibers, polypropylene fibers, aramid fibers, vinylon fibers, polyethylene fibers, polyarylate fibers, PBO fibers, nylon fibers, acrylic fibers, vinyl chloride fibers, cellulose fibers, etc. The organic fibers may melt into a liquid state in a temperature range of about 150°C, but those that do not melt in this temperature range are preferable.

[0038] Examples of inorganic fibers include rock wool, glass fibers, silica fibers, silica-alumina fibers, carbon fibers, and silicon carbide fibers. Such inorganic fibers do not melt when heated and also act as reinforcing materials, thereby enhancing the effects described above.

[0039] Methods for laminating a fibrous sheet to the back surface of a heat-resistant protective sheet include a method in which the mixture obtained by uniformly mixing each component constituting the heat-resistant protective sheet is formed into a sheet, and then the fibrous sheet is laminated to it by pressing or using an adhesive, or a method in which the mixture is laminated onto the fibrous sheet and rolled to form a sheet.

[0040] The present invention provides a method for repairing a heat-resistant protective coating, (1) A step of fitting a heat-resistant protective sheet into the recess of the above-mentioned coating that needs to be repaired, so that it protrudes more than the coating. (2) The process of heating and pressing the heat-resistant protective sheet to make it even, and covering the boundary of the recess, It includes. By using the aforementioned heat-resistant protective sheet and following this process, pressing can be performed efficiently at relatively low temperatures, resulting in good adhesion and finish, and reducing the time and effort required for repairs. Furthermore, repairs can be carried out without compromising the heat-resistant protection.

[0041] Figure 1 shows a cross-sectional view illustrating an embodiment of the coating repair method according to the present invention, and Figure 2 shows a front view. (a) is before repair, (b) is after step (1), and (c) is after step (2).

[0042] As shown in Figure 1(a), the present invention provides a method for repairing a coating by repairing a recess [Figure 1:3] that has formed in a heat-resistant protective coating [Figure 1:2]. In Figure 1(a), an example is shown in which the heat-resistant protective coating [Figure 1:2] in the recess [Figure 1:3] has been completely removed and the shape of the recess has been adjusted. However, it is also possible to make adjustments while leaving the heat-resistant protective coating intact.

[0043] Step (1) of the present invention is a step of fitting a heat-resistant protective sheet [Figure 1:4] into a recess [Figure 1:3] of the coating to be repaired, as shown in Figure 1(b), so that it protrudes more than the coating. In this case, it is preferable to fit the heat-resistant protective sheet [Figure 1:4] with a protrusion [Figure 1:41] that protrudes more than 0.1 to 15 mm, more preferably 0.2 to 10 mm, and even more preferably 0.3 to 5 mm above the heat-resistant protective coating [Figure 1:2].

[0044] When the heat-resistant protective sheet is fitted so that it protrudes beyond the above-mentioned coating, for example, a heat-resistant protective sheet with a thickness greater than (thicker than) the depth of the recess to be repaired should be used. In this case, it is preferable to use a heat-resistant protective sheet that is preferably 0.1 to 15 mm thicker than the depth of the recess, more preferably 0.2 to 10 mm thicker, and even more preferably 0.3 to 5 mm thicker. When using multiple heat-resistant protective sheets, the total thickness should satisfy the above requirements.

[0045] Furthermore, in the present invention, as shown in Figure 1(b), it is preferable to use a heat-resistant protective sheet [Figure 1:4] that is thicker than the heat-resistant protective coating [Figure 1:2]. Specifically, the thickness of the heat-resistant protective sheet is preferably 1.1 times or more and 2 times or less the thickness of the coating. This further enhances the heat-resistant protection of the recess to be repaired.

[0046] In step (1), the heat-resistant protective sheet is fitted so that it protrudes above the coating, so that the heat-resistant protective sheet is filled without creating a gap between it and the edge of the recess to be repaired [Figure 1:32]. In step (2), the heat-resistant protective sheet can be spread evenly around the recess and cover the boundary of the recess [Figure 1:31]. This ensures sufficient heat protection. Furthermore, by using a heat-resistant protective sheet that is thicker than the coating, even better heat protection can be ensured.

[0047] Furthermore, the shape (shape when viewed from the front) and size (area when viewed from the front) of the heat-resistant protective sheet fitted into the recess can be set according to the shape and size of the recess to be repaired. For example, it can be circular, elliptical, triangular, square, rectangular, or rectangular, or it may be irregular in shape. However, if it is made to approximate the shape of the recess to be repaired, preferably the same shape, work efficiency can be improved. In addition, the size of the heat-resistant protective sheet in this invention does not need to be large enough to fit into the recess to be repaired, but it is preferable to use a heat-resistant protective sheet that is approximately the same size as the recess (area when viewed from the front) (approximately 0.9 to 1.1 times). In this case, the heat-resistant protective sheet can be fitted in contact with the edge of the recess [Figure 1:32], and the effects of this invention can be enhanced. Note that Figure 2(a) shows an example in which a heat-resistant protective sheet of the same shape as the square recess is fitted, but it is possible to adjust it as appropriate within the range in which the effects of this invention can be obtained.

[0048] In this invention, one heat-resistant protective sheet of the above thickness and size may be used, but two or more heat-resistant protective sheets may be stacked or placed side by side, and the total thickness and size may be designed as appropriate so as to be within the above thickness and size range. When using heat-resistant protective sheets stacked in the thickness direction, it is preferable to bond them together with an adhesive. When using heat-resistant protective sheets side by side in the planar direction, they may be butted together or arranged with overlapping portions. It is preferable to heat and press these butted portions and overlapping portions to make them smooth in step (3).

[0049] Step (2) is the process of heating and pressing the heat-resistant protective sheet [Figure 1:4] to flatten it and covering the boundary portion of the recess [Figure 1:31], as shown in Figure 1(c).

[0050] In step (2), at least the heat-resistant protective sheet near the boundary of the recess (the outer periphery of the heat-resistant protective sheet), preferably the entire heat-resistant protective sheet, is heated and pressed to level it, and then it is placed over the boundary of the recess [Figure 1:31] as shown in Figures 1(c) and 2(c). The heating temperature is preferably set so that the surface temperature of the heat-resistant protective sheet is 105°C or lower, more preferably 40 to 100°C, and even more preferably 45 to 90°C. Means of heating include, for example, using a heater, dryer, heating iron, or constant temperature incubator, as well as using a pressing device as described later.

[0051] In this invention, the heat-resistant protective sheet can be pressed while it is heated, or it can be pressed after it has been heated and softened or melted, or it can be pressed while the heat-resistant protective sheet is being heated. In this invention, it is preferable to press the heat-resistant protective sheet while it is being heated.

[0052] Examples of pressing tools include trowels, spatulas, and rollers. The materials of such pressing tools can be metal, plastic, etc., with metal being particularly preferred. Furthermore, pressing can be performed while heating, using a heated pressing tool or a pressing tool equipped with a heating mechanism.

[0053] When pressing the heat-resistant protective sheet, it is possible to directly press the heat-resistant protective sheet with a pressing tool, or to interpose various functional sheets (e.g., heat-resistant sheet, release sheet, peelable sheet, etc.) between the heat-resistant protective sheet and the pressing tool. However, in the present invention, it is preferable to directly press the heat-resistant protective sheet with the pressing tool.

[0054] Step (2) is characterized by filling the recess to be repaired with a heat-resistant protective sheet, spreading and leveling the heat-resistant protective sheet around the recess to be repaired, and covering the boundary of the recess with the heat-resistant protective sheet. As a result, the boundary of the recess becomes less noticeable, prevents the intrusion of water, etc. from the boundary, resulting in excellent durability, and also prevents heat from entering from the boundary when the temperature rises, such as during a fire, thereby improving heat protection.

[0055] Figure 3 shows a cross-sectional view illustrating another embodiment of the coating repair method according to the present invention. (a') is before repair, (b) is after step (1), and (c) is after step (2). In the present invention, as shown in Figure 3(a'), before step (1), a primer or adhesive can be applied to the recesses in the coating that need to be repaired. As the primer, a primer used for coatings with heat-resistant protective properties can be used. As the adhesive, there are no particular limitations, but known adhesives such as water-dispersible, water-soluble, and solvent-based adhesives mainly composed of acrylic resin, silicone resin, epoxy resin, vinyl resin, phenolic resin, polyester resin, urethane resin, paraffin, etc. can be used. In addition, additives such as flame retardants, foaming agents, carbonizing agents, and fillers, which are incorporated into the heat-resistant protective sheet, can be added to the adhesive as needed. Note that the adhesive of the present invention also includes adhesives.

[0056] In the present invention, it is preferable to apply an adhesive to the recess to be repaired in the above-mentioned coating. The adhesive can be applied to the recess to be repaired as shown in Figure 3(a'), but it is preferable to apply it to the recess and its vicinity as shown in Figure 4(a'). This makes it possible to further improve adhesion when the heat-resistant protective sheet is spread evenly around the recess and placed over the boundary of the recess in step (2).

[0057] Furthermore, it is preferable to include a step (3) after step (2) in which a topcoat material is applied to the recess to be repaired and its surrounding area. This process (3) improves the finish quality, resulting in a more aesthetically pleasing appearance and enhanced durability. Examples of topcoat materials include acrylic resin-based, urethane resin-based, acrylic silicone resin-based, and fluororesin-based coatings, which can be selected according to the appearance (color tone, gloss, texture, etc.) of the surrounding film. [Examples]

[0058] Examples and comparative examples are shown below to further clarify the features of the present invention.

[0059] ○ Manufacturing of heat-expanding paints The ingredients used are as follows: • Resin [1]: Acrylic styrene resin (50% solids by mass, mineral spirit solution) • Resin [2]: Vinyl acetate emulsion (50% solids by mass, medium: water) • Resin [3]: Urethane resin {polyether polyol (hydroxyl value 24 mg KOH / g, solids content 100% by mass), and hexamethylene diisocyanate (NCO content 23.5%, solids content 100% by mass)} • Heat-resistant powders: Foaming agent (melamine), carbonizing agent (dipentaerythritol), flame retardant (ammonium polyphosphate), filler (titanium dioxide)

[0060] (Thermal foaming paint 1) A binder [1] (solids), a foaming agent (50 parts by mass), a carbonizing agent (50 parts by mass), a flame retardant (230 parts by mass), and a filler (50 parts by mass) were added and mixed uniformly to produce a heat-foaming paint 1. (Thermal foaming paint 2) A heat-expandable paint 2 was produced by uniformly mixing 100 parts by mass (solid content) of binder [2] with 70 parts by mass of foaming agent, 70 parts by mass of carbonizing agent, 300 parts by mass of flame retardant, 70 parts by mass of filler, and additives (dispersant, defoamer, catalyst, etc.). (Thermal foaming paint 3) The main component was prepared by uniformly mixing 90 parts by mass (solids) of polyether polyol [3] with 50 parts by mass of a foaming agent, 50 parts by mass of a carbonizing agent, 250 parts by mass of a flame retardant, 50 parts by mass of a filler, 70 parts by mass of a solvent (xylene), and additives (dispersant, defoamer, catalyst, etc.). Next, 10 parts by mass (solid content) of the binder [3] hexamethylene diisocyanate and 60 parts by mass of the solvent (xylene) were uniformly mixed to prepare a curing agent. The above main component and hardener were mixed to produce a heat-expandable paint 3.

[0061] (Manufacturing of heat-resistant protective sheets) The ingredients used are as follows: • Thermoplastic resin: Ethylene vinyl acetate copolymer resin, melting point 64°C • Heat-resistant powders: Foaming agent (melamine), carbonizing agent (dipentaerythritol), flame retardant (ammonium polyphosphate), filler (titanium dioxide)

[0062] (Heat-resistant protective sheet 1) A mixture of 100 parts by mass of thermoplastic resin, 60 parts by mass of foaming agent, 60 parts by mass of carbonizing agent, 300 parts by mass of flame retardant, and 75 parts by mass of filler was kneaded in a kneader heated to 120°C, rolled, and then allowed to cool to room temperature to produce a heat-resistant protective sheet 1 with a thickness of 3.0 mm. (Heat-resistant protective sheet 2) A heat-resistant protective sheet 2 with a thickness of 2.5 mm was produced by kneading a mixture similar to that of heat-resistant protective sheet 1 in a kneader heated to 120°C, rolling the mixture, and then allowing it to cool to room temperature. (Heat-resistant protective sheet 3) A mixture similar to that used for heat-resistant protective sheet 1 was kneaded in a kneader heated to 120°C. The kneaded mixture was then laminated onto a glass fiber sheet and rolled, after which it was allowed to cool to room temperature to obtain a heat-resistant protective sheet 3 with a thickness of 3.0 mm. In heat-resistant protective sheet 3, the glass fiber sheet side was designated as the back surface, and the other side as the front surface.

[0063] (Example 1) As a test specimen, a steel plate was prepared with an epoxy resin-based rust-preventive primer and a heat-expanding paint 1 (dry film thickness 2.0 mm) applied and laminated. A portion of the coating on this test specimen was cut away to form a square recess (30 mm x 30 mm, depth 2.0 mm). The heat-resistant protective sheet 1 described above was cut into a square (30 mm x 30 mm, 3.0 mm thick), and the resulting heat-resistant protective sheet was fitted into the recess of the test specimen (with a protrusion of 1.0 mm). The surface of the heat-resistant protective sheet was pressed with a metal roller heated to 90°C, and the heat-resistant protective sheet was spread and smoothed so as to cover the boundary of the recess. Using the method described above, the recesses could be repaired efficiently, and the adhesion and finish of the repaired areas were also good. When the surface of this test specimen was heated with a burner, the entire coating, including the repaired areas, foamed up, forming a carbonized heat insulating layer, and the heat-resistant protection was also good.

[0064] (Example 2) The procedure was carried out in the same manner as in Example 1, except that the heat-resistant protective sheet 2 described above was used. As a result, the recesses could be repaired efficiently, and the adhesion and finish of the repaired areas were also good. When the surface of this test specimen was heated with a burner, the entire coating, including the repaired areas, foamed up, forming a carbonized heat insulating layer, and the heat-resistant protection was also good.

[0065] (Example 3) The procedure was carried out in the same manner as in Example 1, except that the heat-resistant protective sheet 3 described above was used. The heat-resistant protective sheet 3 was fitted so that its back side (glass fiber sheet side) faced the bottom of the recess in the test specimen. As a result, the recesses could be repaired efficiently, and the adhesion and finish of the repaired areas were also good. When the surface of this test specimen was heated with a burner, the entire coating, including the repaired areas, foamed up, forming a carbonized heat insulating layer, and the heat-resistant protection was also good.

[0066] (Example 4) The procedure was carried out in the same manner as in Example 1, except that acrylic resin adhesive was applied to the bottom of the square recess in the test specimen. As a result, the recesses could be repaired efficiently, and the adhesion and finish of the repaired areas were also good. When the surface of this test specimen was heated with a burner, the entire coating, including the repaired areas, foamed up, forming a carbonized heat insulating layer, and the heat-resistant protection was also good.

[0067] (Example 5) The procedure was carried out in the same manner as in Example 1, except that acrylic resin adhesive was applied to the square recess and surrounding area of ​​the test specimen. As a result, the recesses could be repaired efficiently, and the adhesion and finish of the repaired areas were also good. When the surface of this test specimen was heated with a burner, the entire coating, including the repaired areas, foamed up, forming a carbonized heat insulating layer, and the heat-resistant protection was also good.

[0068] (Example 6) As a test specimen, a steel plate was prepared with an epoxy resin-based rust-preventive primer and a heat-expanding paint 1 (dry film thickness 2.0 mm) applied and laminated. A portion of the coating on this test specimen was cut away to form a square recess (100 mm x 100 mm, depth 2.0 mm).

[0069] The heat-resistant protective sheet 3 described above was cut into a square (100 mm x 100 mm, 3.0 mm thick), and the back side of the heat-resistant protective sheet was fitted into the recess of the test specimen with the bottom facing the recess of the test specimen (protrusion 1.0 mm). The surface of the heat-resistant protective sheet was pressed with a metal roller heated to 90°C, and the heat-resistant protective sheet was spread and smoothed so as to cover the boundary of the recess. Using the method described above, the recesses could be repaired efficiently, and the adhesion and finish of the repaired areas were also good. When the surface of this test specimen was heated with a burner, the entire coating, including the repaired areas, foamed up, forming a carbonized heat insulating layer, and the heat-resistant protection was also good.

[0070] (Example 7) As a test specimen, a steel plate was prepared with an epoxy resin-based rust-preventive primer and a heat-expanding paint 2 (dry film thickness 2.0 mm) applied and laminated. A portion of the coating on this test specimen was cut away to form a square recess (100 mm x 100 mm, depth 2.0 mm). The heat-resistant protective sheet 3 described above was cut into a square (100 mm x 100 mm, 3.0 mm thick), and the resulting heat-resistant protective sheet was fitted into the recess of the test specimen with the back side facing the bottom of the recess (1.0 mm protrusion). The surface of the heat-resistant protective sheet was pressed with a metal roller heated to 90°C, and the heat-resistant protective sheet was spread and smoothed so as to cover the boundary of the recess. Using the method described above, the recesses could be repaired efficiently, and the adhesion and finish of the repaired areas were also good. When the surface of this test specimen was heated with a burner, the entire coating, including the repaired areas, foamed up, forming a carbonized heat insulating layer, and the heat-resistant protection was also good.

[0071] (Example 8) As a test specimen, a steel plate was prepared with an epoxy resin-based rust-preventive primer and a heat-expanding paint 3 (dry film thickness 2.0 mm) applied and laminated. A portion of the coating on this test specimen was cut away to form a square recess (100 mm x 100 mm, depth 2.0 mm). The heat-resistant protective sheet 3 described above was cut into a square (100 mm x 100 mm, 3.0 mm thick), and the resulting heat-resistant protective sheet was fitted into the recess of the test specimen with the back side facing the bottom of the recess (1.0 mm protrusion). The surface of the heat-resistant protective sheet was pressed with a metal roller heated to 90°C, and the heat-resistant protective sheet was spread and smoothed so as to cover the boundary of the recess. Using the method described above, the recesses could be repaired efficiently, and the adhesion and finish of the repaired areas were also good. When the surface of this test specimen was heated with a burner, the entire coating, including the repaired areas, foamed up, forming a carbonized heat insulating layer, and the heat-resistant protection was also good.

[0072] (Example 9) As a test specimen, a steel plate was prepared with an epoxy resin-based rust-preventive primer and a heat-expanding paint 3 (dry film thickness 5.4 mm) applied and laminated. A portion of the coating on this test specimen was cut away to form a square recess (100 mm x 100 mm, depth 4.0 mm). Two heat-resistant protective sheets were cut from the above heat-resistant protective sheet 1 into squares (100mm x 100mm, 3.0mm thick), and these were layered and bonded together with adhesive (acrylic resin adhesive) to obtain a heat-resistant protective sheet laminate with a total thickness of 6.0mm. The laminate described above was fitted into the recess of the test specimen (protrusion 2.0 mm), and the surface of the heat-resistant protective sheet was pressed with a metal roller heated to 90°C, spreading and leveling the heat-resistant protective sheet so that it covered the boundary of the recess. Using the method described above, the recesses could be repaired efficiently, and the adhesion and finish of the repaired areas were also good. When the surface of this test specimen was heated with a burner, the entire coating, including the repaired areas, foamed up, forming a carbonized heat insulating layer, and the heat-resistant protection was also good.

[0073] (Example 10) As a test specimen, a steel plate was prepared with an epoxy resin-based rust-preventive primer and a heat-expandable paint 3 (dry film thickness 5.4 mm) applied and laminated. A portion of the coating on this test specimen was cut away to form a square recess (100 mm x 100 mm, depth 5.4 mm). Two heat-resistant protective sheets were cut from the above heat-resistant protective sheet 3 into squares (100mm x 100mm, 3.0mm thick) and glued together to obtain a heat-resistant protective sheet laminate with a total thickness of 6.0mm. In this case, the back surface of the second (upper) heat-resistant protective sheet was layered on top of the surface of the first (lower) heat-resistant protective sheet. The laminate was fitted into the recess of the test specimen with the back side (glass fiber sheet side) facing the bottom of the recess (0.6 mm protrusion), and the surface of the heat-resistant protective sheet was pressed with a metal roller heated to 90°C, spreading and leveling the heat-resistant protective sheet so that it covered the boundary of the recess. Using the method described above, the recesses could be repaired efficiently, and the adhesion and finish of the repaired areas were also good. When the surface of this test specimen was heated with a burner, the entire coating, including the repaired areas, foamed up, forming a carbonized heat insulating layer, and the heat-resistant protection was also good.

Claims

1. A method for repairing a heat-resistant protective coating, (1) A step of fitting a heat-resistant protective sheet into the recess of the coating to be repaired, so that it protrudes more than the coating. (2) Heating and pressing the heat-resistant protective sheet to level it, and covering the boundary of the recess, Includes, The above-mentioned heat-resistant protective sheet is characterized by containing a thermoplastic resin with a melting point of 105°C or lower, and a heat-resistant powder, as a method for repairing a coating.

2. The method for repairing a coating according to claim 1, characterized in that the heat-resistant protective sheet is thicker than the thickness of the coating.

3. The method for repairing a coating according to claim 1, characterized in that the thickness of the heat-resistant protective sheet is 1.1 times or more and 2 times or less the thickness of the coating.

4. The method for repairing a coating according to claim 1, characterized in that, in step (1) above, a heat-resistant protective sheet is brought into contact with and fitted into the small end of the recess.

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