Fireproof repair agent, and repair method

Abstract

To provide a fireproof repair agent that can be used to repair fire-resistant materials in locations other than factories, such as construction sites, and that has good workability during repair.SOLUTION: The fireproof repair agent is a resin composition comprising resin, a plasticizer, and heat-expandable components. The resin comprises a thermoplastic resin, and the thermoplastic resin is a plastisol in which the thermoplastic resin is dispersed in a sol state in the plasticizer.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a refractory repair agent and a repair method using the refractory repair agent.

Background Art

[0002] Structural materials of buildings, which are important elements in terms of structure, may be coated with refractory materials to protect them from fire. The refractory material can expand during a fire to form a heat-insulating layer and protect the structural material of the building from flames and heat during a fire. Conventionally, as the refractory material, a refractory sheet obtained by previously molding a refractory resin composition containing thermally expandable graphite into a sheet shape is known.

[0003] Also, as the refractory material, refractory paints are known. As the refractory paint, for example, as disclosed in Patent Document 1, those containing a foaming agent, a carbonizing agent, an inorganic powder, and a binder are known. The refractory paint is generally applied and constructed by diluting it with an organic solvent and applying it to structural materials and the like.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, although the refractory sheet is generally wound around and attached to the structural material of the building at the construction site, if the shape of the structural material is complicated, the workability when attaching it to the structural material may decrease.

[0006] On the one hand, refractory coatings can be applied relatively easily even when the shape of the structural material is complex. However, dripping may occur when applying to structural materials, etc., and the drying time and curing time after application take more than a certain amount of time, so the workability is not good. Furthermore, in order for refractory materials to exhibit sufficient refractory performance, a certain thickness or more is required. However, when trying to increase the thickness of refractory coatings, dripping is likely to occur, and the drying time and curing time are even more necessary, and the workability is likely to deteriorate.

[0007] In recent years, for example, regarding the structural materials of buildings, it is often the case that after pre-coating construction using refractory materials at the factory, the structural materials are transported to the construction site. However, during transportation, the structural materials may collide with each other, and a part of the refractory material covering the structural material may be damaged. When such damage occurs, the surface of the structural material is exposed at the damaged location, and there is a risk of reduced fire resistance, so it is necessary to repair the damage. In that case, it is necessary to take the structural material back to the factory and perform the coating construction again for repair, which is a problem that takes time.

[0008] Therefore, an object of the present invention is to provide a refractory repair agent that can repair refractory materials at locations other than factories such as construction sites and has good workability during repair.

Means for Solving the Problems

[0009] As a result of intensive studies, the present inventors have found that the refractory repair agent is a resin composition containing a resin, a plasticizer, and a thermally expandable component, and further, the resin contains a thermoplastic resin, and the thermoplastic resin is a plastisol dispersed in a sol state in the plasticizer, and by making it like this, the above problems can be solved. That is, the present invention provides the following [1] to

[12] .

[0010] [1] A refractory repair agent which is a resin composition containing a resin, a plasticizer, and a thermally expandable component, wherein the resin contains a thermoplastic resin, and the thermoplastic resin is a plastisol dispersed in a sol state in the plasticizer. [2] The refractory repair agent according to [1], wherein the resin contains at least one selected from the group consisting of polyvinyl chloride resins and acrylic resins. [3] The refractory repair agent according to [1] or [2], wherein the thermal expansion component is at least one selected from the group consisting of thermally expandable layered inorganic substances and foaming agents. [4] The refractory repair agent according to [3], wherein the thermally expandable layered inorganic substance is thermally expandable graphite. [5] The refractory repair agent according to [3], wherein the foaming agent is a nitrogen-containing compound-based foaming agent. [6] The refractory repair agent according to [5], further containing a carbonizing agent. [7] A repair method of applying the refractory repair agent according to any one of [1] to [6] to a workpiece to be coated and curing it by heating. [8] The repair method according to [7], wherein the workpiece to be coated is preheated and then the refractory repair agent is applied. [9] The repair method according to [7] or [8], wherein the refractory repair agent is applied to a defective portion of the workpiece to be coated whose surface is covered with a refractory material or a portion not covered with the refractory material.

[10] The repair method according to any one of [7] to [9], wherein the structural material of a building is the workpiece to be coated.

[11] The repair method according to any one of [7] to

[10] , wherein any one of a steel frame or a wooden beam or column is the workpiece to be coated.

[12] The repair method according to any one of [7] to

[11] , wherein the body of a vehicle is the workpiece to be coated. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a refractory repair agent that can be repaired even at a location other than a factory such as a construction site and has good workability during repair. [Brief Description of the Drawings]

[0012]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0013] [Refractory Repair Agent] Hereinafter, the present invention will be described with reference to embodiments. The refractory repair agent of the present invention is a resin composition containing a resin, a plasticizer, and a thermally expandable component. Hereinafter, each component used in the refractory repair agent will be described in detail.

[0014] [Resin] The resin used in the refractory repair agent includes a thermoplastic resin. By including a thermoplastic resin as the resin, the refractory repair agent gently softens when heated, voids are formed during softening, and the plasticizer enters the voids, whereby the refractory repair agent gradually loses fluidity and changes to a gel state. Therefore, the refractory repair agent can prevent dripping from occurring by being heated after coating, for example, when coated on a heated object to be coated, and can improve the appearance of the coating film. Furthermore, it is easy to increase the film thickness with a single coating, and the workability when repairing a defective portion is improved.

[0015] The refractory repair agent of the present invention is a plastisol in which a thermoplastic resin exists as particles and is dispersed in a sol state in a plasticizer. By being a plastisol, the refractory repair agent can be easily applied to the object to be coated. Further, in the refractory repair agent, since the thermoplastic resin exists as particles in a sol state, when softened by heating, the plasticizer easily enters the voids, and the workability is easily improved. Furthermore, after the particulate thermoplastic resin is gelled, by further advancing the molten state by heating, the particle shape disappears and it integrates with the plasticizer. Therefore, upon cooling after heating, the refractory repair agent becomes a solid-state (also referred to as "quasi-cured") coating film, and the mechanical strength and the like in the coating film are excellent. Incidentally, after the refractory repair agent of the present invention is applied to the object to be coated, it is necessary to heat for a certain period of time to quasi-cure, but since the heating time can be shortened even if the coating film is thick, the workability is good.

[0016] Specific resins used for the refractory repair agent include polyvinyl chloride-based resins and acrylic resins. The polyvinyl chloride-based resin and the acrylic resin are preferably thermoplastic resins. These resins can form a sol state in the refractory repair agent, and at the same time, the plasticizer can enter by heating and gelation can easily occur, so the workability is further easily improved. Among these, polyvinyl chloride-based resins are preferred.

[0017] The polyvinyl chloride-based resin (PVC) may be a homopolymer obtained by polymerizing vinyl chloride alone, or may be a copolymer of vinyl chloride as a main component and a monomer copolymerizable therewith. By using a copolymer, it becomes possible to adjust the glass transition temperature and lower the heating temperature described later. Examples of monomers copolymerizable with vinyl chloride include olefin compounds such as ethylene and propylene, vinyl esters such as vinyl acetate and vinyl propionate, unsaturated monocarboxylic acids such as acrylic acid and methacrylic acid, unsaturated monocarboxylic acid esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, N,N-dimethylaminoethyl methacrylate, unsaturated amides such as acrylamide and methacrylamide, unsaturated nitriles such as acrylonitrile and methacrylonitrile, unsaturated dicarboxylic acids such as maleic acid and fumaric acid, their esters and their anhydrides, N-substituted maleimides, vinyl ethers such as vinyl methyl ether and vinyl ethyl ether, vinylidene compounds such as vinylidene chloride, and the like. The monomers copolymerizable with vinyl chloride may be used alone or in combination of two or more. The polyvinyl chloride-based resin preferably has a constituent unit derived from vinyl chloride of 80% by mass or more, more preferably 90% by mass or more.

[0018] The polyvinyl chloride-based resin is preferably a so-called paste PVC dispersed in a sol state in a plasticizer. Examples of commercially available polyvinyl chloride-based resins used for paste PVC include the Leuron Paste (registered trademark) series manufactured by Tosoh Corporation, the ZEST (registered trademark) series of Shin Daiichi Vinyl Co., Ltd., the Kanevynil (registered trademark) paste series manufactured by Kaneka Corporation, and the like.

[0019] The acrylic resin is preferably a (meth)acrylic polymer. The (meth)acrylic polymer is a polymer obtained by polymerizing a monomer having a (meth)acryloyl group (also referred to as a “(meth)acrylic monomer”) or a monomer containing acrylonitrile, and may be a homopolymer obtained by polymerizing one of the (meth)acrylic monomers and acrylonitrile alone, or a copolymer obtained by polymerizing two or more of these monomers. The (meth)acrylic polymer is preferably a polymer obtained by polymerizing a monomer containing a (meth)acrylic monomer.

[0020] Examples of the (meth)acrylic monomer include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and n-octyl (meth)acrylate; cyclic alkyl (meth)acrylates such as cyclohexyl (meth)acrylate; carboxyl group-containing monomers such as methacrylic acid, acrylic acid, 2-succinoyloxyethyl-2-methacryloyloxyethyl succinate methacrylate, 2-maleinoyloxyethyl-2-methacryloyloxyethyl maleate methacrylate, 2-phthaloyloxyethyl-2-methacryloyloxyethyl phthalate methacrylate, and 2-hexahydrophthaloyloxyethyl-2-methacryloyloxyethyl hexahydrophthalate methacrylate; phosphate group-containing (meth)acrylates such as 2-(meth)acryloyloxyethyl acid phosphate; hydroxyl group-containing (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate; carbonyl group-containing (meth)acrylates such as acetoacetoxyethyl (meth)acrylate; amino group-containing (meth)acrylates such as N-dimethylaminoethyl (meth)acrylate and N-diethylaminoethyl (meth)acrylate; acrylamide derivatives such as acrylamidodiacetone acrylamide, N-methylolacrylamide, N-methoxymethylacrylamide, N-ethoxymethylacrylamide, and N-butoxymethylacrylamide; and polyfunctional (meth)acrylates such as (poly)ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate. Among these, the (meth)acrylic monomer preferably contains at least one of alkyl (meth)acrylate, methacrylic acid, and acrylic acid.

[0021] (Meta)acrylic polymers may be polymers of the above-mentioned (meta)acrylic monomers or polymers of (meta)acrylic monomers and acrylonitrile. However, they may also be polymers of at least one of acrylonitrile and (meta)acrylic monomers and monomers other than acrylonitrile and (meta)acrylic monomers. Examples of monomers other than acrylonitrile and (meta)acrylic monomers include styrene derivatives such as styrene, α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, etc.; polyfunctional monomers such as divinylbenzene, divinylnaphthalene, divinyl ether; maleic acid derivatives such as itaconic acid, crotonic acid, maleic acid, maleic acid esters, maleic anhydride; fumaric acid derivatives such as fumaric acid, fumaric acid esters; and triaryl isocyanurate, etc.

[0022] (Meta)acrylic polymers preferably have either constituent units derived from (meta)acrylic monomers or constituent units derived from acrylonitrile as the main component, and more preferably have constituent units derived from (meta)acrylic monomers as the main component. Here, the main component means that it is contained in the (meta)acrylic polymer in an amount of 50% by mass or more, preferably 70% by mass or more.

[0023] The acrylic resin is preferably an acrylic sol dispersed in a sol state in a plasticizer. The structure of the particles of the acrylic resin in the acrylic sol is not particularly limited, and examples include a single structure, a core-shell structure of two or more layers, or a gradient structure in which the composition continuously changes from the central part to the outer part of the polymer particles. Among these, a core-shell structure with different compositions for each layer is preferred. By adopting a core-shell structure, the dispersibility in the plasticizer can be enhanced, and the gelling temperature can be appropriately adjusted. Examples of commercially available acrylic resins used in acrylic sols include the Dianal LP series manufactured by Mitsubishi Chemical Corporation.

[0024] The content of the thermoplastic resin in the refractory repair agent is preferably 10 to 60% by mass, more preferably 20 to 50% by mass, and even more preferably 25 to 45% by mass based on the total amount of the refractory repair agent. If the content of the thermoplastic resin is at least the above lower limit, the refractory repair agent can be appropriately gelled by heating and is also likely to undergo pseudo-curing. On the other hand, if it is at most the above upper limit, it becomes easier to contain a certain amount or more of components other than the resin, such as a plasticizer and a thermally expandable component, in the refractory repair agent.

[0025] Also, the resin contained in the refractory repair agent may be composed of a thermoplastic resin, but as long as the effects of the present invention are achieved, it may contain resins other than the thermoplastic resin. Examples of resins other than the thermoplastic resin include thermosetting resins and photocurable resins. In the refractory repair agent, the content of the resin other than the thermoplastic resin may be, for example, 50 parts by mass or less, preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less with respect to 100 parts by mass of the thermoplastic resin. Note that it is preferable that the refractory repair agent does not contain a resin other than the thermoplastic resin, and the content of the resin other than the thermoplastic resin may be 0 parts by mass or more. The resin other than the thermoplastic resin may be contained as a sol in the plasticizer in the refractory repair agent or may be contained in other forms.

[0026] <Plasticizer> The plasticizer contained in the refractory repair agent can be appropriately selected from known ones and used. Specifically, examples include phthalate plasticizers, aliphatic ester plasticizers, trimellitate plasticizers, and phosphate plasticizers. Note that the plasticizer is usually a liquid at normal temperature (23°C).

[0027] Examples of phthalate plasticizers include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, di-n-octyl phthalate, diisononyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, and the like. Examples of aliphatic ester plasticizers include adipic acid ester plasticizers such as dimethyl adipate, dibutyl adipate, diisobutyl adipate, dihexyl adipate, di-2-ethylhexyl adipate, diisononyl adipate, di-n-octyl adipate, di-n-decyl adipate, diisodecyl adipate, bis[2-(2-butoxyethoxy)ethyl] adipate, and bis(2-butoxyethyl) adipate; and aliphatic ester plasticizers other than adipic acid ester plasticizers such as di-2-ethylhexyl azelate, dibutyl sebacate, di-2-ethylhexyl sebacate, diethyl succinate, methyl acetyl ricinoleate, and glyceryl triacetate.

[0028] Examples of trimellitic acid ester plasticizers include tri-2-ethylhexyl trimellitate, tri-n-octyl trimellitate, tridecyl trimellitate, triisodecyl trimellitate, di-n-octyl-n-decyl trimellitate, and the like. Examples of phosphate plasticizers include trimethyl phosphate, triethyl phosphate, tributyl phosphate, tri-2-ethylhexyl phosphate, tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl phenyl phosphate, and the like.

[0029] Among the above, phthalate plasticizers and aliphatic ester plasticizers are preferred as plasticizers, and among them, phthalate plasticizers and adipic acid ester plasticizers are more preferred. Also, from the viewpoint of reducing environmental load, plasticizers other than phthalate plasticizers are preferred, and particularly adipic acid ester plasticizers are preferred. The plasticizer may be used alone or in combination of two or more of the above-mentioned ones.

[0030] The content of the plasticizer in the refractory repair agent is preferably 40 to 240 parts by mass, more preferably 60 to 180 parts by mass, and still more preferably 70 to 150 parts by mass with respect to 100 parts by mass of the resin contained in the refractory repair agent. When the content of the plasticizer is 40 parts by mass or more, the resin, especially the thermoplastic resin, is easily dispersed in a sol state in the plasticizer, and is easily gelled and pseudo-cured by heating, making it easier to further improve workability. Also, it is easy to impart a certain degree of flexibility to the coating film formed by the refractory repair agent. On the other hand, when the content of the plasticizer is 240 parts by mass or less, it is possible to prevent the viscosity during coating from becoming low, making it easier to form a coating film with a large film thickness. Also, it is easy to suppress the occurrence of dripping after coating, and furthermore, it is easy to impart a certain degree of mechanical strength to the coating film.

[0031] <Thermal expansion component> As the thermal expansion component contained in the refractory repair agent, a thermally expandable layered inorganic substance, a foaming agent, etc. can be used. The thermally expandable layered inorganic substance is a conventionally known substance that expands when heated, and examples include vermiculite, thermally expandable graphite, etc., and thermally expandable graphite is particularly preferred. As the thermally expandable layered inorganic substance, particulate or flaky ones may be used. Since the thermally expandable layered inorganic substance expands when heated to form a large volume of voids, the coating film formed from the refractory repair agent can form a heat insulation layer with excellent heat insulation performance during a fire.

[0032] Thermally expandable graphite is obtained by treating powders such as natural flake graphite, pyrolytic graphite, and kish graphite with an inorganic acid and a strong oxidizing agent to form a graphite intercalation compound, and it is a kind of crystalline compound that maintains the layered structure of carbon. Examples of the inorganic acid include concentrated sulfuric acid, nitric acid, and selenic acid. Examples of the strong oxidizing agent include concentrated nitric acid, persulfate, perchloric acid, perchlorate, permanganate, dichromate, dichromate, and hydrogen peroxide. The thermally expandable graphite obtained by the acid treatment as described above may be further neutralized with ammonia, aliphatic lower amines, alkali metal compounds, alkaline earth metal compounds, etc.

[0033] The particle size of the thermally expandable graphite is preferably 20 to 200 mesh. When the particle size of the expandable graphite is within the above range, it is easy to expand and create a large volume of voids, so the fire resistance is improved. Also, the dispersibility in the resin is improved. The average aspect ratio of the thermally expandable graphite is preferably 2 or more, more preferably 5 or more, and even more preferably 10 or more. The upper limit of the average aspect ratio of the thermally expandable graphite is not particularly limited, but from the viewpoint of preventing cracking of the thermally expandable graphite, it is preferably 1,000 or less. When the average aspect ratio of the thermally expandable graphite is 2 or more, it is easy to expand and create a large volume of voids, so the flame retardancy is improved. The average aspect ratio of the thermally expandable graphite is obtained by measuring the maximum dimension (major axis) and the minimum dimension (minor axis) for each of 10 thermally expandable graphites, and taking the average value of the values obtained by dividing the maximum dimension (major axis) by the minimum dimension (minor axis) as the average aspect ratio. The major axis and minor axis of the thermally expandable graphite can be measured using, for example, a field emission scanning electron microscope (FE-SEM).

[0034] The foaming agent used for the thermally expandable component is a foaming agent that foams upon heating, and is preferably a nitrogen-containing compound-based foaming agent. When the nitrogen-containing compound-based foaming agent is heated, it thermally decomposes, sublimes, or vaporizes at a certain temperature or higher, generating gases such as nitrogen and ammonia. Therefore, a coating film formed by a refractory repair agent containing a nitrogen-containing compound-based foaming agent is likely to form a heat-insulating layer with excellent heat-insulating performance during a fire.

[0035] Examples of nitrogen-containing compound-based blowing agents include phosphate-based compounds such as ammonium phosphate, ammonium polyphosphate, melamine phosphate, and melamine polyphosphate; melamine-based compounds such as melamine, methylol melamine, melamine cyanurate, and melamine-formaldehyde resin; metal azodicarboxylate salts such as azodicarbonamide and barium azodicarboxylate; azo compounds such as azobisisobutyronitrile; nitroso compounds such as N,N'-dinitrosopentamethylenetetramine; hydrazine derivatives such as hydrazodicarbonamide, 4,4'-oxybis(benzenesulfonylhydrazide), and toluenesulfonylhydrazide; semicarbazide compounds such as toluenesulfonyl semicarbazide, etc. Among these, from the viewpoint of foaming temperature, etc., phosphate-based compounds and melamine-based compounds are preferred. By using these blowing agents, it becomes easier to form a heat-insulating layer with good heat-insulating performance in the coating film. In addition, the phosphate-based compound acts as a catalyst to promote the polymerization of the charring agent described later when heated during a fire, and the phosphate-based compound itself can form an inorganic phosphate film, enhancing the fire resistance and heat-insulating performance of the coating film. Among the nitrogen-containing compound-based blowing agents, ammonium polyphosphate and melamine are preferred. The thermally expandable component may be used alone or in combination of two or more.

[0036] The content of the thermally expandable component in the fire-resistant repair agent is preferably 10 to 140 parts by mass, more preferably 20 to 100 parts by mass, and still more preferably 30 to 80 parts by mass with respect to 100 parts by mass of the resin contained in the fire-resistant repair agent. When the content of the thermally expandable component is 10 parts by mass or more, the coating film formed by the fire-resistant repair agent can expand appropriately when heated during a fire and form a heat-insulating layer with excellent heat-insulating performance. Also, by setting it to 100 parts by mass or less, the ratio of the resin and plasticizer in the fire-resistant repair agent can be made a certain level or more, so that the viscosity of the fire-resistant repair agent can be appropriately adjusted, and gelation and pseudo-curing can be appropriately carried out when heated. Furthermore, it becomes easier to improve the mechanical strength of the coating film, etc.

[0037] <Charring agent> The refractory repair agent of the present invention may contain a carbonizing agent. When the carbonizing agent is heated by a fire and the heat-insulating layer is formed by the above-mentioned thermally expandable component, a carbonized layer can be formed to improve the heat-insulating performance of the heat-insulating layer. The carbonizing agent can be preferably used when a foaming agent, particularly a nitrogen-containing compound-based foaming agent, is used as the above-mentioned thermally expandable component. The carbonizing agent preferably polymerizes by heating during a fire to form a carbonized layer.

[0038] When the refractory repair agent contains a carbonizing agent, it preferably further contains an acidic component that reacts with the carbonizing agent during heating to promote polymerization. The acidic component may be an acidic substance that exhibits acidity at normal temperature, or may be a substance that generates an acidic substance by decomposition or the like during heating. As the acidic component, phosphates, particularly polyphosphates, are preferable, and particularly, phosphate-based compounds that can also be used as the above-mentioned foaming agent are preferable, and among them, ammonium polyphosphate is more preferable. That is, when the refractory repair agent contains a carbonizing agent, it preferably contains the above-mentioned phosphate-based compound that also functions as a foaming agent. In addition, when the refractory repair agent contains a carbonizing agent, from the viewpoint of sufficiently promoting foaming during a fire to form a heat-insulating layer with excellent heat-insulating properties, in addition to phosphates, it preferably further contains a foaming agent other than phosphates, and among them, it is more preferable to further contain a melamine-based compound.

[0039] As the carbonizing agent, polyhydric alcohols are preferable, and among them, polyhydric alcohols having three or more hydroxyl groups are more preferable. By using a polyhydric alcohol as the carbonizing agent, particularly a polyhydric alcohol having three or more hydroxyl groups, a carbonized layer can be appropriately formed by the carbonizing agent. Specific examples of the polyhydric alcohol used as the carbonizing agent include polyhydric alkanols such as pentaerythritol, dipentaerythritol, pentaerythritol, dipentaerythritol, tripentaerythritol, trimethylolpropane, ditrimethylolpropane, tritrimethylolpropane, or their 2-4 mers, and polysaccharides such as cellulose.

[0040] The content of the carbonizing agent in the refractory repair agent is preferably 2 to 40 parts by mass, more preferably 4 to 25 parts by mass, and even more preferably 6 to 20 parts by mass with respect to 100 parts by mass of the resin contained in the refractory repair agent. When the content of the carbonizing agent is 2 parts by mass or more, it becomes easier to improve the heat insulation property by the carbonized layer formed by the carbonizing agent. Further, when it is 40 parts by mass or less, it becomes easier to exhibit an effect commensurate with the content.

[0041] When the refractory repair agent contains a carbonizing agent, as described above, it preferably contains both a phosphate-based compound such as ammonium polyphosphate and a melamine-based compound. When the refractory repair agent contains both a phosphate-based compound and a melamine-based compound, the content of the phosphate-based compound is preferably 5 to 80 parts by mass, more preferably 15 to 65 parts by mass, and even more preferably 25 to 55 parts by mass with respect to 100 parts by mass of the resin contained in the refractory repair agent. Further, the content of the melamine-based compound is preferably 2 to 25 parts by mass, more preferably 4 to 20 parts by mass, and even more preferably 6 to 15 parts by mass with respect to 100 parts by mass of the resin contained in the refractory repair agent. In addition, when both a phosphate-based compound and a melamine-based compound are contained, the mass ratio of the content of the melamine-based compound to the content of the phosphate-based compound (melamine-based compound / phosphate-based compound) is, for example, 1 / 20 to 1, but the content of the phosphate-based compound is preferably more than the content of the melamine-based compound, and the above mass ratio is preferably 1 / 15 to 9 / 10, and more preferably 1 / 8 to 1 / 2.

[0042] <Flame retardant> The refractory repair agent of the present invention may further contain a flame retardant. Examples of the flame retardant include those other than the above-mentioned thermally expandable components, and specifically, phosphate-containing flame retardants, boron-containing flame retardants, metal hydroxide-based flame retardants, halogen-based flame retardants, and other metal-containing compounds.

[0043] Examples of the phosphate-containing flame retardant include phosphates composed of salts of phosphoric acids and at least one selected from metals of Groups IA to IVB of the periodic table. The phosphoric acids are not particularly limited, and may be monophosphoric acids such as phosphoric acid, phosphorous acid, hypophosphorous acid, etc., or may be pyrophosphoric acid, polyphosphoric acid, etc. Examples of the metals of Groups IA to IVB of the periodic table include lithium, sodium, calcium, barium, iron (II), iron (III), aluminum, etc. In addition, the above-mentioned phosphate-containing flame retardant may be subjected to known water resistance improvement treatments such as treatment with a silane coupling agent and coating with a melamine resin.

[0044] Specific examples of the phosphate-containing flame retardant include, for example, monophosphates, pyrophosphates, polyphosphates, etc. The monophosphates are not particularly limited, and examples include sodium salts such as monosodium phosphate, disodium phosphate, trisodium phosphate, monosodium phosphite, disodium phosphite, sodium hypophosphite, etc., potassium salts such as monopotassium phosphate, dipotassium phosphate, tripotassium phosphate, monopotassium phosphite, dipotassium phosphite, potassium hypophosphite, etc., lithium salts such as monolithium phosphate, dilithium phosphate, trilithium phosphate, monolithium phosphite, dilithium phosphite, lithium hypophosphite, etc., barium salts such as barium dihydrogen phosphate, barium hydrogen phosphate, barium phosphate, barium hypophosphite, etc., magnesium salts such as magnesium hydrogen phosphate, magnesium hydrogen phosphate, magnesium phosphate, magnesium hypophosphite, etc., calcium salts such as calcium dihydrogen phosphate, calcium hydrogen phosphate, tricalcium phosphate, calcium hypophosphite, etc., zinc salts such as zinc phosphate, zinc phosphite, zinc hypophosphite, etc., and aluminum salts such as aluminum phosphite. The polyphosphates are not particularly limited, and examples include aluminum polyphosphate. As the phosphate-containing flame retardant used in the present invention, aluminum salts such as aluminum phosphite are preferred.

[0045] Examples of the boron-containing flame retardant used in the present invention include borax, boron oxide, boric acid, borate, etc. Examples of boron oxide include diboron trioxide, boron trioxide, diboron dioxide, tetraboron trioxide, tetraboron pentoxide, etc. Examples of borates include borates of alkali metals, alkaline earth metals, Group 4, Group 12, or Group 13 elements of the periodic table. Specifically, alkali metal borate salts such as lithium borate, sodium borate, potassium borate, cesium borate, alkaline earth metal borate salts such as magnesium borate, calcium borate, barium borate, zirconium borate, zinc borate, aluminum borate, etc. are included. The boron-containing flame retardant used in the present invention is preferably a borate, and more preferably zinc borate.

[0046] Examples of the metal hydroxide-based flame retardant include metal hydroxides such as magnesium hydroxide, calcium hydroxide, aluminum hydroxide, iron hydroxide, nickel hydroxide, zirconium hydroxide, titanium hydroxide, zinc hydroxide, copper hydroxide, vanadium hydroxide, tin hydroxide, etc. As the metal hydroxide, aluminum hydroxide is preferred.

[0047] Examples of halogen-based flame retardants include chlorine-based flame retardants and bromine-based flame retardants, with bromine-based flame retardants being preferred. The bromine-based flame retardants are not particularly limited as long as they are compounds containing bromine in their molecular structure, and examples thereof include aromatic brominated compounds. Specific examples of aromatic brominated compounds include monomeric organic bromine compounds such as hexabromobenzene, pentabromotoluene, hexabromobiphenyl, decabromobiphenyl, hexabromocyclodecane, decabromodiphenyl ether, octabromodiphenyl ether, hexabromodiphenyl ether, bis(pentabromophenoxy)ethane, ethylenebis(pentabromophenyl), ethylenebis(tetrabromophthalimide), tetrabromobisphenol A, etc., brominated polycarbonates such as polycarbonate oligomers produced from brominated bisphenol A, copolymers of the above polycarbonate oligomer and bisphenol A, diepoxy compounds produced by the reaction of brominated bisphenol A and epichlorohydrin, brominated epoxy compounds such as monoepoxy compounds obtained by the reaction of brominated phenols and epichlorohydrin, poly(brominated benzyl acrylate), brominated polyphenylene ether, brominated bisphenol A, condensates of cyanuric chloride and brominated phenol, brominated polystyrenes such as brominated (polystyrene), poly(brominated styrene), crosslinked brominated polystyrene, and halogenated bromine compound polymers such as crosslinked or non-crosslinked brominated poly(α-methylstyrene).

[0048] Examples of metal-containing compounds other than the above compounds include metal oxides such as aluminum oxide, titanium oxide, calcium oxide, magnesium oxide, iron oxide, tin oxide, antimony oxide, titanium oxide, etc., metal carbonates such as calcium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, etc., and metal sulfates such as calcium sulfate, barium sulfate, magnesium sulfate, etc. Among these, metal oxides and metal carbonates are preferred, and titanium oxide and calcium carbonate are more preferred. The flame retardant may be used alone or in combination of two or more of the above-mentioned ones.

[0049] The content of the flame retardant in the refractory repair agent is preferably 5 to 170 parts by mass, more preferably 10 to 150 parts by mass, and still more preferably 20 to 120 parts by mass with respect to 100 parts by mass of the resin contained in the refractory repair agent. When the content of the flame retardant is 5 parts by mass or more, the flame retardancy of the coating film formed by the refractory repair agent with the flame retardant can be improved. Also, when it is 120 parts by mass or less, other components such as resin, plasticizer, and thermal expansion component can be contained in the refractory repair agent at a sufficient ratio.

[0050] <Other additives> The refractory repair agent of the present invention can contain additive components other than the above as necessary, as long as the object of the present invention is not impaired. The type of this additive component is not particularly limited, and various additives can be used. Examples of such additives include inorganic fillers, lubricants, shrinkage preventives, crystal nucleating agents, coloring agents (pigments, dyes, etc.), ultraviolet absorbers, antioxidants, anti-aging agents, flame retardant aids, antistatic agents, surfactants, vulcanizing agents, dispersants, and surface treatment agents other than the above-mentioned flame retardants and thermal expansion components. The addition amount of the additive can be appropriately selected as long as the object of the present invention is not impaired. These additives may be used alone or in combination of two or more.

[0051] The refractory repair agent of the present invention is preferably substantially solvent-free. Note that being substantially solvent-free means that the refractory repair agent does not contain an organic solvent and water, or even if it contains them, the amount is trace. Specifically, the total content of water and solvent in the refractory repair agent is preferably 3% by mass or less, more preferably 1% by mass or less, still more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less with respect to the total amount of the refractory repair agent. Since the refractory repair agent is substantially solvent-free, it does not need to be dried after coating, so the workability is improved, and it is also easy to reduce the environmental load.

[0052] (Method for producing refractory repair agent) The refractory repair agent of the present invention can be obtained by mixing the components constituting the refractory repair agent. For example, a resin containing a thermoplastic resin, a thermally expandable component, and further a carbonizing agent, a flame retardant, and other additives that are blended as necessary can be added to a plasticizer and mixed. The refractory repair agent is a plastisol as described above. Therefore, the mixing of each component may be performed by stirring with a known mixer so that the thermoplastic resin can be dispersed in the plasticizer in a sol state. In addition, components other than the thermoplastic resin, such as the thermally expandable component, the carbonizing agent, the flame retardant, the resin other than the thermoplastic resin, and other additives, may be dispersed in the plasticizer or dissolved by the above mixing.

[0053] (Method of using the refractory repair agent) The refractory repair agent of the present invention is preferably used as a coating film for repairing the refractory material covering the object to be coated. Specifically, for example, as shown in FIG. 1, when there is at least one defect 12 on the surface of the refractory material 11 covering the object to be coated 10, it is preferable to repair the refractory material 11 by filling the location where the defect 12 has occurred (defect location) with the refractory repair agent 13 of the present invention.

[0054] The refractory material 11 may be a coating film formed from a conventionally known refractory paint, or may be a coating film formed from a refractory coating agent composed of a resin composition containing a resin, a plasticizer, and a thermally expandable component, which is a plastisol in which a thermoplastic resin is dispersed in a sol state in the plasticizer. In addition, the refractory coating agent may contain a flame retardant, a carbonizing agent, and other additives in addition to the above components, similar to the refractory repair agent. Since the components contained in the refractory coating agent and their contents are as described in the above description of the refractory repair agent, the description thereof is omitted.

[0055] In addition, the refractory material 11 may be other than the coating film formed from the above-described refractory paint and refractory coating agent, etc., and may be a refractory sheet previously formed into a sheet shape, etc. The refractory sheet is a resin sheet containing a thermally expandable component such as thermally expandable graphite. As the refractory sheet, a commercially available product may be used, and for example, "Fiblock" manufactured by Sekisui Chemical Co., Ltd. may be used. The thickness of the refractory material 11 is not particularly limited, but is preferably 0.3 to 10 mm, more preferably 0.8 to 8 mm, and even more preferably 1 to 6 mm. By the thickness of the refractory material being 0.3 mm or more, appropriate refractory performance can be imparted by the refractory material. Also, by making it 10 mm or less, it is possible to prevent the refractory material from becoming thicker than necessary, and even when forming with a coating film, it can be formed with high workability.

[0056] Among these, from the viewpoint of improving the fire resistance and appearance after repair, it is preferably a refractory coating agent. Also, the refractory coating agent for forming the coating film of the refractory material 11 may have the same composition as the refractory repair agent or a different composition. Also, the refractory material 11 may be made of the same material as the refractory repair agent 13 or a different material from the refractory material 11, but it is preferably made of the same material as the refractory material 11. Note that being made of the same material means that the types of resins contained in the refractory material 11 are the same. For example, when the resin used for the refractory material 11 is a polyvinyl chloride-based resin, the resin used for the refractory repair agent may also be a polyvinyl chloride-based resin. Also, it is more preferable that the thermally expandable components are the same. When the thermally expandable component contained in the refractory material 11 is expandable graphite, the thermally expandable component used for the refractory repair agent may also be expandable graphite.

[0057] Note that FIG. 1 shows an example of an H-shaped steel in which the shape of the object to be coated 10 is H-shaped, but as will be described later, the shape and material of the object to be coated 10 are not limited to H-shaped steel, and other shapes and materials may be used. Also, FIG. 1 shows the case where the entire surface of the object to be coated 10 is covered with a coating film formed by the refractory material 11 and the refractory repair agent 13, but as will be described later, only a part of the surface of the object to be coated 10 may be covered with the coating film. In addition, in this specification, an object to be coated covered with a coating film formed of a refractory material and a refractory repair agent may simply be referred to as a "structural body".

[0058] Generally, for example, when transporting a structural member covered with a refractory material to a construction site, the structural members may collide with each other due to vibrations during transportation, etc., and a part of the refractory material may peel off from the structural member, resulting in a defect in the refractory material. Also, for example, after a structural member covered with a refractory material is brought into a construction site, during the construction of a building, if the structural member lifted by a crane or the like accidentally collides with a pillar or the like of the building under construction, a defect may occur in the refractory material. Furthermore, for example, after a long period has elapsed since the construction of the refractory material, defects may occur due to aging deterioration. In the above cases, by repairing the defect with a refractory repair agent, the fire resistance of the structural member can be maintained. Also, the refractory repair agent of the present invention can be repaired at locations other than the factory. Therefore, for example, even when a defect occurs during the construction of a building or a defect occurs in the refractory material due to aging deterioration after a structural member covered with a refractory material is brought into a construction site, by using the refractory repair agent, it is possible to repair the defect at the construction site without taking the building materials back to the factory.

[0059] In the above description, the case of applying a refractory repair agent to the defective portion of the refractory material has been described, but the refractory repair agent may also be used in other cases. For example, the refractory repair agent may be applied to a portion not covered with a refractory material other than the defective portion. Specifically, when cutting or processing an object to be coated covered with a refractory material, the cross-section formed by the cutting or processing will not be covered with the refractory material. Therefore, it may be used in such a manner as to cover such a cross-section with a refractory repair agent. When processing building materials or the like whose surfaces are pre-coated with refractory materials at a construction site, for example, parts that need to be coated with refractory materials may not be coated with refractory materials. However, according to this aspect, refractory materials can be coated on parts to be coated with refractory materials in a simple manner even at a construction site or the like.

[0060] Also, the thickness of the coating film formed by the refractory repair agent is not particularly limited. However, when filling in defective parts, it may be appropriately adjusted according to the thickness of the refractory material and the depth of the defect generated in the refractory material. Preferably, after repairing the refractory material, the thickness should be such that there is no step between the refractory material and the refractory repair agent. Also, when forming a coating film of the refractory replenishing agent on a part not coated with a refractory material such as a cut or processed cross-section, the thickness may be the same as the thickness of the refractory material. The thickness of the coating film formed by the refractory repair agent is not particularly limited, but is preferably 0.1 to 10 mm, more preferably 0.3 to 8 mm, and still more preferably 1 to 6 mm.

[0061] The method of applying the refractory repair agent to the object to be coated is not particularly limited. Examples include a method of spray coating (spray coating) the refractory repair agent on the surface of the object to be coated, a known coating machine such as a coating robot, a method of applying the refractory repair agent to the surface of the object to be coated with a brush or roller, and a method of applying it by plastering. Among these, when repairing a large-area part, spray coating is preferred. By adopting spray coating, even if the object to be coated has a complex shape, a coating film with no gaps and a uniform thickness can be formed to repair the refractory material. Also, the refractory material can be easily repaired at locations other than factories such as construction sites. Also, when repairing a relatively small-area part of about 10 cm square or less, from the viewpoint of simplifying the repair of the refractory material, it is preferable to apply the refractory repair agent by plastering.

[0062] In addition, the refractory repair agent applied to the object to be coated is preferably heated. More specifically, it is preferable to apply the refractory repair agent to the heated object to be coated. When the refractory repair agent is applied to the object to be coated and heated, its fluidity is lost and it gels. Therefore, dripping after coating can be prevented. In addition, the thickness of the coating film can be adjusted by adjusting the heating temperature of the object to be coated.

[0063] When applying the refractory repair agent to the heated object to be coated, it is advisable to pre-heat the object to be coated before application. For example, in spray coating, it is advisable to spray the refractory repair agent onto the heated object to be coated. The object to be coated may be heated to a temperature higher than the temperature of the refractory repair agent described below. For example, it may be heated to about 45 - 180°C, preferably 80 - 170°C, and more preferably 100 - 150°C. The method of pre-heating the object to be coated is not particularly limited. The object to be coated may be heated by putting it into a heating oven, or it may be heated by hot air, an infrared heater, etc. Also, the object to be coated may be heated as a whole, but it is preferable that only the part where the refractory repair agent is applied is locally heated. When locally heating, it is preferable to use a heat gun or the like for heating.

[0064] On the other hand, the temperature of the refractory repair agent during application (for example, in spray coating, the temperature of the refractory agent during spray atomization) may be around room temperature. For example, it may be about 0 - 50°C, preferably 10 - 40°C, and more preferably 20 - 30°C. When the refractory repair agent is applied at a temperature near room temperature, it can be maintained in a sol state with fluidity before adhering to the object to be coated. Therefore, it can be applied to the object to be coated with high workability. For example, it is also possible to repair the refractory material by applying it to the object to be coated without gaps and with a uniform thickness.

[0065] The refractory repair agent may be further heated (hereinafter also referred to as "secondary heating") after being applied to the workpiece heated as described above. The refractory repair agent on the workpiece, by secondary heating, causes the thermoplastic resin to further melt and the particle shape to disappear, integrating with the plasticizer. Therefore, the refractory repair agent, after cooling after secondary heating, becomes a pseudo-cured solid-state coating film, and the mechanical strength and the like of the obtained coating film are excellent. In secondary heating, the refractory repair agent may be heated to, for example, about 80 to 180°C, preferably 100 to 150°C. Also, the secondary heating is preferably performed until the particle shape of the thermoplastic resin in the refractory repair agent disappears. There is no limit to the heating time, but it may be performed, for example, for about 1 to 60 minutes, preferably 2 to 30 minutes. The method of further heating the refractory repair agent on the workpiece is not particularly limited, but the workpiece coated with the refractory repair agent may be put into a heating oven and heated, or may be heated by hot air, an infrared heater, or the like. Also in secondary heating, the workpiece may be heated as a whole, but it is preferable that only the portion where the refractory repair agent is applied is locally heated. When locally heating, it is preferable to use a heat gun or the like.

[0066] In addition, the formation of the coating film on the workpiece described above may be carried out in a factory or the like, but when the workpiece is, for example, a building, it is preferably carried out at the construction site. By forming the coating film at the construction site, the repair of the refractory can be carried out without bringing the coated objects such as building materials back to a factory or the like.

[0067] The workpiece is a member that needs to be protected during a fire, and examples include the structural materials of a building and the bodies of various vehicles. That is, the refractory repair agent of the present invention may be used for structural materials of a building and for the bodies of vehicles. Note that the structural material is a member that forms the framework in a building and is a member that bears the forces applied to the building, such as the weight and load of the members constituting the building.

[0068] The structural materials of building materials are heated during a fire, resulting in a decrease in strength, or they burn, causing the building to collapse. However, by covering these surfaces with a refractory material and a refractory repair agent, a heat-insulating layer will be formed on these surfaces when a fire occurs. Therefore, heating and combustion can be suppressed, and the collapse of the building can be prevented.

[0069] Also, by covering the surfaces of the members that make up the vehicle body with a refractory material and a refractory repair agent, it is possible to prevent a fire from spreading throughout the vehicle when a fire occurs in a part of the vehicle. Therefore, in a vehicle equipped with a battery such as a lithium-ion battery (LIB), even if the battery undergoes thermal runaway and catches fire due to an internal short circuit or the like, it is possible to prevent the fire from spreading throughout the vehicle.

[0070] Examples of the materials of the structural materials that can be the object to be coated include metal materials such as wood and steel, concrete, bricks, concrete blocks, and stones. Among these, metal materials such as steel are preferred. Metal materials are easy to heat and hardly deform even when heated. Therefore, for example, by applying a refractory repair agent to a heated metal material, it is easy to form a thick coating film without deforming the object to be coated. The shape of the object to be coated is not particularly limited. It may be a flat plate shape, or it may have a cross-sectional shape such as a polygon such as an H-shape, Z-shape, L-shape, U-shape, V-shape, cylindrical shape, round shape, triangular shape, quadrangular shape, pentagonal shape, or it may have other shapes.

[0071] Among the things that make up the structural materials of building materials, the object to be coated is preferably steel or wood, but steel is more preferred. Also, more specific examples of the structural materials that make up the object to be coated include either a steel-frame structure or a wooden beam or column. Among these, a steel-frame structure is preferred. In addition, in various vehicles, examples of the object to be coated include the vehicle body as described above. Here, examples of the vehicle may include automobiles, trains, steam locomotives, railway vehicles such as trains, construction heavy machinery such as forklifts and excavator trucks, vehicles such as carts and amusement park vehicles, or vehicles other than ships and airplanes. Among these, automobiles are preferred. Further, the refractory repair agent is preferably used for underbody coat applications. Therefore, the object to be coated is preferably the underbody of an automobile.

[0072] Note that the entire surface of the object to be coated may be covered with a coating film formed of a refractory material and a refractory repair agent, or only a part of the surface of the object to be coated may be covered with a coating film formed of a refractory material and a refractory repair agent.

Examples

[0073] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0074] [Examples 1 to 6, Comparative Example 1] (Preparation of refractory repair agent) After adding components other than the plasticizer to the plasticizer, the mixture was stirred at 3000 rpm for 3 minutes at room temperature using a laboratory disper to prepare a refractory repair agent composed of plastisol.

[0075] (Coating of refractory repair agent) A plate-shaped steel material with a thickness of 4 mm and a size of 50 mm × 50 mm was supported using a magnet jig so that the 50 mm × 50 mm surface was perpendicular to the liquid surface, immersed in a dip solution at room temperature, and then pulled out to coat the surface of the steel material with a refractory coating agent. At this time, by adjusting the heating conditions of the steel material to 50°C, 70°C, and 120°C respectively, the film thickness after pseudo-curing was adjusted to 0.5 mm, 1 mm, and 3 mm. Further, the refractory coating agent was cured by heating at 130°C for 30 minutes to obtain a steel material with a refractory coating film formed on the surface. Note that the coated refractory coating agent had the same composition as the subsequently coated refractory repair agent. A 2 cm square refractory coating film was cut out from the refractory coating film formed on the steel material, and the refractory repair agent prepared by the above method was applied by plastering to the cut-out portion. When applying the refractory repair agent, the refractory repair agent was applied so that the film thickness of the refractory repair agent became the same as the film thickness of the refractory coating film prepared before the above cutting.

[0076] (Curing of refractory repair agent) The steel plate coated with the refractory repair agent was put into an oven at 130 °C for the specified time shown in Table 1 to cure the refractory repair agent, and then taken out of the oven to obtain a structure in which one surface of the steel plate was covered with the coating film of the refractory repair agent.

[0077] [Evaluation method] The refractory repair agents of each example and comparative example were evaluated by the following evaluation method. [Dripping property] As shown in FIG. 2, a sample 20 in which a refractory coating film 22 was formed on a steel plate 21 and the refractory coating film 22 was cut out from a 2 cm square cut-out portion 23 was set vertically, and after applying the refractory repair agent to the cut-out portion 23 on the vertical surface, it was visually confirmed whether there was dripping when the refractory repair agent was pseudo-cured or cured (hereinafter, the dripping evaluation using the sample 20 is also referred to as "Evaluation 1"). Also, as a more difficult evaluation, as shown in FIG. 3, a sample 30 having the same configuration as the sample 20 was made horizontal so that the refractory coating film 22 and the cut-out portion 23 were on the lower side, and then the dripping evaluation was performed (hereinafter, the dripping evaluation using the sample 30 is also referred to as "Evaluation 2"). In Evaluation 2, the cut-out portion 23 was pre-heated to 120 °C with a heat gun in a state where the sample 30 was horizontal, and further, after applying the refractory repair agent by plastering in a state where the sample 30 was horizontal, it was evaluated after holding down the refractory repair agent for 30 seconds. In each of the above evaluations, the case where there was no dripping was designated as "A", and the case where there was dripping was designated as "B".

[0078] [Appearance evaluation] In the structures obtained in each of the examples and comparative examples, the appearance of the surface coated with the refractory repair agent was visually observed to confirm the smoothness. When the surface was smooth, it was evaluated as "A", and when the surface was not smooth, it was evaluated as "B".

[0079] <Curing time> The part coated with the refractory repair agent by plastering was heated at 120 °C with a heat gun, returned to room temperature, pressed with a cylinder having a diameter of 5 mm, and the time until no adhesion to the cylinder was observed was defined as the curing time and shown in Table 1.

[0080] <Refractory property> The structures obtained in each of the comparative examples and examples were put into an electric furnace heated to 600 °C and taken out after 30 minutes. The thickness of the coating film before and after heating was measured, and when the expansion ratio determined by the ratio of the thickness after heating to the thickness before heating was 4 times or more, it was rated as "A", and when it was less than 4 times, it was rated as "B". In each of the comparative examples and examples, the evaluation of the refractory property was carried out using a structure having a coating film thickness of 3 mm.

[0081] Each component used in the examples and comparative examples is as follows. (Resin) PVC(1): Polyvinyl chloride-based resin, thermoplastic resin, trade name "ZEST PQ92", manufactured by Shin Daiichi Vinyl Co., Ltd. PVC(2): Polyvinyl chloride-based resin, thermoplastic resin, trade name "Luron Paste 850", manufactured by Tosoh Corporation Acrylic resin: Trade name "Dianal BR-106", manufactured by Mitsubishi Chemical Corporation

[0082] (Plasticizer) Phthalic acid-based: Diisodecyl phthalate, trade name "DIDP", manufactured by Daihachi Chemical Industry Co., Ltd. Adipic acid-based: Bis[2-(2-butoxyethoxy)ethyl] adipate, trade name "BXA-N", manufactured by Daihachi Chemical Industry Co., Ltd. (Thermally expandable component) Ammonium polyphosphate: Trade name "APP422", manufactured by Clariant Melamine: Melamine, trade name "Melamine", manufactured by Mitsui Chemicals, Inc. Expansive graphite (1): Trade name "ADT351", manufactured by ADT Expansive graphite (2): Trade name "CA60N", manufactured by Air Water Co., Ltd. (Carbonizing agent) Pentaerythritol: Trade name "Pentalit", manufactured by Koei Chemical Co., Ltd. (Flame retardant) Calcium carbonate: Trade name "BF-300", manufactured by Shiraishi Calcium Co., Ltd. Titanium oxide: Trade name "A-100", manufactured by Ishihara Sangyo Co., Ltd. Aluminum phosphite: Trade name "APA100", manufactured by Taihei Chemical Industry Co., Ltd. (Solvent) Methyl ethyl ketone: Fuji Film Wako Pure Chemical

[0083]

Table 1

[0084] As is clear from the above examples, the refractory repair agents of Examples 1 to 6 contained a resin, a plasticizer, and a thermally expandable component, and since the resin was a thermoplastic resin, even when the thickness of the coating film was increased, no dripping occurred, the surface appearance was good, the curing time was short, and it was possible to perform double-sided coating with a single application, and the workability was excellent. In addition, by containing a thermally expandable component, it could expand appropriately and the refractory performance was also good. Therefore, it satisfied the performance required for repairing refractory materials. On the other hand, the refractory repair agent prepared in Comparative Example 1 was diluted with a solvent without containing a plasticizer, so dripping occurred, the surface appearance was not good when the thickness of the coating film was increased, and the curing time was also long, and the workability could not be improved. Therefore, it did not satisfy the performance required for repairing refractory materials.

Explanation of symbols

[0085] 10 Workpiece to be coated 11 Refractory 12 Defect 13 Refractory repair agent Samples for evaluating dripping properties of 20 and 30 21 Steel plate 22 Fire-resistant coating 23 Cut-out part

Claims

1. A refractory repair agent which is a resin composition containing a resin, a plasticizer, and a thermally expandable component, wherein the resin contains a thermoplastic resin, and the thermoplastic resin is a plastisol dispersed in a sol state in the plasticizer.

2. The refractory repair agent according to Claim 1, wherein the resin contains at least one selected from the group consisting of polyvinyl chloride resins and acrylic resins.

3. The refractory repair agent according to Claim 1 or 2, wherein the thermally expandable component is at least one selected from the group consisting of thermally expandable layered inorganic substances and foaming agents.

4. The refractory repair agent according to Claim 3, wherein the thermally expandable layered inorganic substance is thermally expandable graphite.

5. The refractory repair agent according to Claim 3, wherein the foaming agent is a nitrogen-containing compound-based foaming agent.

6. The refractory repair agent according to Claim 5, further comprising a carbonizing agent.

7. A repair method of applying the refractory repair agent according to Claim 1 or 2 to a workpiece to be coated and curing it by heating.

8. The repair method according to Claim 7, wherein the workpiece to be coated is preheated and then the refractory repair agent is applied.

9. The repair method according to Claim 7, wherein the refractory repair agent is applied to a defective portion of the workpiece to be coated whose surface is covered with a refractory material or a portion not covered with the refractory material.

10. The repair method according to Claim 7, wherein a structural member of a building is used as the workpiece to be coated.

11. The repair method according to Claim 7, wherein any one of a steel frame or a wooden beam or column is used as the workpiece to be coated.

12. The repair method according to Claim 7, wherein a vehicle body is used as the workpiece to be coated.

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