JP3027233B2 - Fire joint structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint structure provided with fire prevention measures.

[0002]

2. Description of the Related Art Fire prevention measures for buildings are being promoted mainly for exterior materials and base materials. As a result, the fire protection performance is improved in the part of the exterior material, but joints, which are seams between the exterior materials, are relatively weak to fire. Joint structures with fire prevention measures are required. As shown in FIG. 4, the conventional joint structure for fire prevention is to insert a noncombustible material 13 into the joint bottom between the exterior materials 2 and 2 attached on the base material 1 and to provide a cosmetic and cosmetic on the joint. It is configured by inserting a fixed watertight material 14 having fire resistance. This incombustible material 13 is usually made of foamed asbestos. If the thickness of such a noncombustible material 13 is small, it does not have fire protection performance. Therefore, it is necessary to have a large thickness, and it is impossible to reduce the thickness. Moreover,
It is necessary to exactly match the width and length of the joints, but gaps are likely to occur due to widening of the joints due to aging after construction or heat during a fire.

[0003]

Since the depth of the joint is determined by the thickness of the exterior material, if the thick incombustible material is at the joint bottom, the joint becomes shallower by that amount, and the fixed watertight material is occupied. The resulting thickness is reduced. Since the watertightness of the sealing material is affected by the thickness of the sealing material at the joint, if the joint is shallow, it is difficult to ensure watertightness.

[0004] Therefore, an object of the present invention is to provide a joint structure in which fire prevention measures are taken, and in which watertight performance is easily ensured.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a joint formed by inserting a sealing material into a joint between an exterior material and / or an interior material attached on a base material. In the structure, facing the joint, the surface of the base material, the end face of the exterior material and / or the interior material, and
At least one of the surfaces of the sealing material is characterized in that a fire-protection coating layer comprising a fire-protection composition containing the following components (A), (B), (C), (D) and (E) is formed. To provide a fire joint structure. (A) Polyalkylene ether polymer 10 having a hydrolyzable silicon functional group represented by the following formula 2 at a molecular chain terminal:
0 parts by weight.

[0006]

Embedded image

(B) 20 to 150 parts by weight of microcapsules formed by coating ammonium polyphosphate powder with a resin. (C) 15 to 75 parts by weight of a polyhydric alcohol. (D) 5 to 50 parts by weight of an amino group-containing compound which generates a gas containing a nitrogen atom upon heating. (E) 0.1 to 10 parts by weight of a silanol compound condensation catalyst.

[0008] In the present invention, for example,
A fire-resistant material such as a Zn steel plate (for example, a galvanized steel plate having a coating amount of 270 g / m ^{2 on} both sides) and a gypsum board is used, but plywood, particle board, asbestos slate, hard fiber board, soft fiber board ( General board materials such as insulation boards) are also used. Instead of a board, a frame material may be used.

The exterior material used in the present invention is, for example, fly ash slag cement board (NFC: abbreviation for fiber-containing fly ash slag cement board), asbestos slate, asbestos cement calcium silicate board, autoclave-cured lightweight cellular concrete (ALC) : Autoclaved Lig
Materials having flame retardancy (or fire resistance) such as htweight concrete are preferred, but are not limited thereto. The interior material is also not particularly limited, and a commonly used material such as gypsum board can be used.

An exterior material and / or an interior material is mounted on the base material by an arbitrary method to form joints such as vertical joints (joint joints) and horizontal joints (overlap joints).
The sealing material used in the present invention is, for example, a silicone-based or modified silicone-based material, and a fixed watertight material to be injected and filled into joints is generally a gasket formed into an appropriate shape, but is not limited thereto. It is not done. As the standard watertight material, for example, EPDM rubber (ethylene / propylene / dimethyl rubber) or the like is used, and insertion is performed by press fitting or the like.

In the present invention, the components (A), (B), (C), and (C) are provided on at least one of the surface of the base material, the end surface of the exterior material, the end surface of the interior material, and the surface of the sealing material facing the joint.
A fire protection coating layer comprising a fire protection composition containing (D) and (E) is formed. This fireproof coating layer foams by heating to form a porous carbonized layer having closed cells. The polyalkylene ether polymer (A) is essentially -R-
It has a molecular chain (main chain) composed of chemically bonded repeating units represented by O- (R is an alkylene group). These repeating units may be bonded by only one type, or may be bonded by mixing two or more types of units. In the present invention, those having a main chain of polyether produced from propylene oxide as a raw material, that is, polypropylene ether, are preferable because they have a high molecular weight and are liquid at room temperature. The value of a is selected for the hydrolyzable silicon functional group at the end of the main chain from the viewpoint of the physical properties (elongation) of the sealant (combustion composition), and b is selected so as to form an ether bond with the main chain. Is selected. The hydrolyzable group (X) bonded to the silicon atom is preferably an alkoxy group, and more preferably a methoxy group from the viewpoint of curability. The average molecular weight of the polyalkylene ether polymer (A) is from 1,000 to 30,000
Preferably in the range of 5000 to 15000
Is more preferable. If the molecular weight is less than 1000,
The resulting cured product may have poor flexibility,
If it exceeds 000, the viscosity of the composition may increase and the workability may decrease. The polyalkylene ether polymer (A) is used alone or as a mixture of two or more.

[0012] Ammonium polyphosphate acts as a dehydration catalyst. That is, in a heating environment, the organic matter is dehydrated and carbonized to form a fire-resistant carbonized layer, and also itself forms a fire-resistant inorganic phosphoric acid film. Further, it also has a function as a foaming agent that decomposes upon heating to generate ammonia gas and expands organic substances. In the present invention, the ammonium polyphosphate powder is completely or almost completely covered with the resin and used in the form of microcapsules. In this state, the solubility in water at 20 ° C. is at most 0.3% by weight or less, usually 0.1% by weight or less, and sufficient water resistance as a fire-resistant coating film can be secured. Examples of the method of microencapsulation include an interfacial polymerization method, an in situ polymerization method, a submerged curing method, a spray drying method, and other methods. Here, for example, the interfacial polymerization method is a reaction method in which two kinds of reaction components are respectively dissolved in two kinds of solvents which are not mixed with each other to produce a polymer compound at an interface between both liquid phases, and the in-situ polymerization method is used. Synthetic method is a method that utilizes a synthesis reaction, submerged curing method is a method that utilizes property changes, and spray drying method is a method of spraying an encapsulated stock solution, contacting it with hot air, and drying volatiles It is. The resin that can be used for microencapsulation may be any resin that forms a film that is hardly permeable to water and has excellent water resistance, such as vinyl chloride resin, vinylidene chloride resin, epoxy resin, urethane resin, acrylic resin, and phenol. Resins, vinyl acetate resins, cellulosic resins, alkyd resins, shellac resins, diallyl phthalate resins, polyamide resins, melamine resins, urea resins, and the like can be used, and they can be used alone or as a mixture of two or more. Among these resins, a melamine formaldehyde resin is preferably used from the viewpoints of more complete coating with the resin, water resistance of the resin, strength of the capsule, and finer encapsulation.

The particle size of the microcapsules is 100 μm
The following is preferred. When the ratio of the particle diameter of more than 100 μm increases, the water resistance of the fire-resistant coating film for a long period of time may not be ensured. On the other hand, if the particle size is large, elongation during application of the fire-retardant composition is impaired, which is not preferable. Ammonium polyphosphate has a phosphorus content of 31.5 ± 0.5% by weight,
Nitrogen content 14.5 ± 0.5% by weight, decomposition temperature 275 ° C
The above is preferred.

The blending amount of the microcapsules (B) must be 20 to 150 parts by weight based on 100 parts by weight of the polyalkylene ether polymer (A). The amount is 2
If the amount is less than 0 parts by weight, the entire organic substance cannot be effectively carbonized, and sufficient foaming cannot be expected. If it exceeds 150 parts by weight, the coating film is hard and brittle due to the addition of polyhydric alcohols (C) such as mono-, di- or tri-pentaerythritol, amino group-containing compounds (D), and inorganic fillers. Become a membrane.

The polyhydric alcohol (C) is an indispensable component as a foam-type fire-resistant coating film because it expands upon heating and is carbonized by a dehydration catalyst to form a desired foamed carbonized film. Examples of such polyhydric alcohols include, for example, mono-, di- or tri-pentaerythritol. The blending amount of the polyhydric alcohol (C) needs to be 15 to 75 parts by weight based on 100 parts by weight of the polyalkylene ether polymer (A). If the compounding amount is less than 15 parts by weight, the expansion by heating is insufficient, a large expansion ratio cannot be obtained, and the carbonized film formed by dehydration is also a small film. If the amount exceeds 75 parts by weight, the expandability corresponding to the compounding amount cannot be expected. In addition, there is a limit naturally due to the compounding of ammonium polyphosphate and the amino group-containing compound (D). The film becomes hard and brittle.

The amino group-containing compound (D) is used as a foaming agent, and generates a gas such as nitrogen or ammonia by heating. Specifically, melamine is preferably used, and in addition, benzoguanamine, urea, dicyandiamide, azodicarbonamine and the like are used. The compounding amount of the amino group-containing compound (D) must be 5 to 50 parts by weight based on 100 parts by weight of the polyalkylene ether polymer (A). If the compounding amount is less than 5 parts by weight, the effect as a foaming agent is insufficient, and if it exceeds 50 parts by weight, the foamed carbonized film formed by heating becomes too soft, and passes through the carbonized state by combustion, leaving only ash. In addition, disadvantages such as being hard and brittle as a coating film occur due to the balance with other compounding agents.

As the silanol compound condensation catalyst (E), for example, those known as silanol condensation catalysts can be used. For example, alkyl titanates, organosilicon titanates, tin octylates, dibutyltin laurate, dibutyltin maleate, metal salts of carboxylic acids such as dibutyltin phthalate, amine salts such as dibutylamine-2-ethylhexoate, and the like; Known silanol condensation catalysts such as other acidic catalysts and basic catalysts are effectively used, and these may be used alone or in combination of two or more.

The compounding amount of the silanol compound condensation catalyst (E) must be 0.1 to 10 parts by weight based on 100 parts by weight of the polyalkylene ether polymer (A).
0.5 to 5 parts by weight is preferred. If the compounding amount is less than 0.1 part by weight, it is difficult to obtain an appropriate curing speed, and if it exceeds 10 parts by weight, the curing is too fast or the rubber strength of the obtained cured product is lowered, so neither is preferable. .

[0019] In addition to the components (A) to (E), other components can be appropriately added to the fire-retardant composition as needed. Inorganic filler that generates steam by heating
"Inorganic filler a") may be optionally blended. The blending of the inorganic filler a has an effect of significantly delaying the burning rate of the fire-resistant coating film. As the inorganic filler a, for example,
Aluminum hydroxide, magnesium hydroxide, kaolin,
Calcium hydrogen phosphate, hectorite, sodium sulfite heptahydrate, ettringite, alumite (alnite), talc (bluesite), diaspore, gibbsstone (hydrargillite), kaolinite, montmorillonite, serpentine, Slaked lime, gypsum and the like can be mentioned.

The amount of the inorganic filler a is 120 parts by weight based on 100 parts by weight of the polyalkylene ether polymer (A).
It is preferably at most part by weight. The amount of the inorganic filler a is 120
Exceeding the weight part is not preferred because the coating film becomes hard and brittle or the foaming ratio decreases. An inorganic filler other than the inorganic filler a (hereinafter, referred to as “inorganic filler b”) or a coloring pigment may be added to the fire-preventing composition. For example, reinforcing fillers such as fumed silica, precipitated silica, silicic anhydride, hydrous silicic acid and carbon black; calcium carbonate, magnesium carbonate, diatomaceous earth, calcined clay, clay, talc, titanium oxide, bentonite, organic bentonite Fillers and pigments such as fibrous fillers such as asbestos, glass fibers and glass filaments, and pigments such as ferric oxide, zinc oxide, activated zinc white, and shirasu balloon; These are used alone or in combination of two or more.

The compounding amounts of the inorganic filler b and the coloring pigment are as follows:
The amount is preferably 100 parts by weight or less based on 100 parts by weight of the polyalkylene ether polymer (A). When the blending amount of the inorganic filler b and the coloring pigment exceeds 100 parts by weight, the viscosity of the fire-prevention composition becomes too high, or the cured film becomes hard and brittle. The fire-retardant composition includes a plasticizer; a thixotropic agent such as hydrogenated castor oil; a light stabilizer such as a hindered amine or a hindered phenol; an antioxidant; an ultraviolet absorber; a phenol resin or a silane coupling agent; And an organic pigment such as phthalocyanine blue.

As the plasticizer, for example, a general-purpose plasticizer is used. For example, phthalic acid esters such as dioctyl phthalate, dibutyl phthalate and butyl benzyl phthalate; second basic fatty acid esters such as dioctyl adipate, isodecyl succinate and dibutyl sebacate; glycols such as diethylene glycol dibenzoate, pentaerythritol ester Esters; fatty acid esters such as butyl oleate and methyl acetyl ricinoleate; phosphate esters such as tricresyl phosphate and trioctyl phosphate; chlorinated paraffin and the like. 100 to 10 as plasticizer
It is also possible to use a liquid resin having a molecular weight of about 000. For example, xylene resin, polybutadiene,
Polyoxypropylene glycol, polyoxypropylene triol, polyester resin, acrylic oligomer, nitrile-butadiene rubber (NBR), styrene-
Liquid materials such as butadiene rubber (SBR) and polysulfide rubber can be used.

In order to form a fire-protection coating layer comprising the above-described fire-protection composition on at least one of the surface of the base material, the end surface of the exterior material, the end surface of the interior material and the surface of the sealing material facing the joint,
For example, the following method is adopted. In the case of forming a fire-resistant coating layer on the surface of the base material, the fire-preventive composition is applied to at least the joints of the base material after the base material is manufactured and before the exterior material and / or the interior material is attached, After attaching the exterior material and / or the interior material, the base material surface at the joint bottom is painted. When a fire protection coating layer is formed on the end surface of the exterior material, the fire-resistant composition is applied to the end surface of the exterior material after the exterior material is manufactured and before the base material is attached, or the joint side surface is attached after the exterior material is attached. Or painting on the end face. The formation of the fire protection coating layer on the end surface of the interior material can be performed in the same manner as the case of the end surface of the exterior material. When the fire-resistant coating layer is formed on the surface of the fixed watertight material (including the end face), the fire-resistant composition is applied to at least one of the side surface and the bottom surface of the fixed watertight material inserted into the joint. You paint. These coatings can be carried out, for example, with a caulking gun with the fire-protecting composition in a cartridge, but are not limited thereto. After application of the fire-retardant composition, the main component (organopolysiloxane) when the fire-retardant composition is silicone-based
And a catalyst (acetoxysilane) to cause the reaction of the following formula 3;

[0024]

Embedded image

When the fire-retardant composition is a modified silicone-based composition, the main component (modified silicone polymer) and a catalyst (tin compound) cause a reaction of the following formula 4;

[0026]

Embedded image

Dry and cure to form a coating film. Since the fire-preventing composition described above foams, for example, about 8 to 20 times by heating at the time of fire or the like, the coating after drying is applied to have a thickness of, for example, about 3 to 5 mm. With this thickness, the exterior and interior materials are typically 10-12
Since it has a thickness of mm, when a coating film is formed on the joint bottom, a sufficient depth of the sealing material to exhibit sufficient watertightness or airtightness is secured.

The application site of the fireproof joint structure of the present invention is not particularly limited as long as it is a joint portion where fireproofing is required. For example, the outer wall, ceiling, roof,
The present invention can be arbitrarily applied to joints of exterior and / or interior surfaces of various buildings such as floors. Hereinafter, the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment of a fireproof joint structure according to the present invention. As shown in FIG. 1, this fireproof joint structure is obtained by inserting a fixed watertight material 40 into a joint between exterior materials 2 and 2 attached on a base material 1.
A fire-protection coating layer 30 made of a fire-prevention composition containing the above-mentioned components (A) to (E) is formed on the entire outer surface of one side. The fire protection coating layer 30 faces the joint floor while being attached on the base material 1. In this embodiment, the sealant need not be regular. When the fire-resistant coating layer is formed as in this example, it is expected that dew condensation is likely to occur, and the contact surface of the base material with the exterior material and / or the interior material will be rust-proof by the fire-resistant coating film layer. it can.

FIG. 2 shows a second embodiment of the fireproof joint structure according to the present invention. As shown in FIG. 2, the fireproof joint structure includes a fixed watertight material 41 inserted between joints 2 and 2 attached on the base material 1. The above components (A) to (E) are provided on portions of the surface of the fixed watertight material 41 inserted into the joints, that is, on the side and bottom surfaces having irregularities.
A fire-protection coating layer 31 made of a fire-prevention composition containing: The fire protection coating layer 31 may be formed only on the side surface or only on the bottom surface of the standard watertight material 41.

FIG. 3 shows a third embodiment of the fire joint structure according to the present invention. As shown in FIG. 3, the fireproof joint structure includes a fixed watertight material 42 inserted into the joint between the exterior materials 2 and 2 attached on the base material 1. On the surface of the base material 1 at the joint bottom, a fire protection coating layer 32 made of a fire protection composition containing the above components (A) to (E) is formed.
In this embodiment, the sealing material does not need to be a fixed one, but may be a (paste-like) sealing material contained in a cartridge.

[0032]

A fire protection coating layer having a fire protection function is formed on at least one of the surface of the base material, the end surface of the exterior material, the end surface of the interior material, and the surface of the fixed watertight material. Since the fireproof coating layer is foamed by heating to increase the volume, the thickness of the coating film does not need to be too large. For this reason, exterior materials and / or
Alternatively, all or most of the joints between the interior materials can be used for a standard watertight material, and sufficient watertight performance can be ensured. In addition, since the fire-resistant coating layer is foamed by heating to form a porous carbonized layer having closed cells, it is possible to prevent a flame from entering from joints and prevent a fire from spreading. Even if the joint width is widened due to aging, fire, or the like, the fireproof coating layer foams and increases in volume due to heating during a fire, so that the gap can be closed.

[0033]

EXAMPLES Specific examples and comparative examples of the present invention will be shown below, but the present invention is not limited to the following examples. (Preparation of fire-retardant composition) Kaneka MS polymer (manufactured by Kanegafuchi Chemical Industry Co., Ltd .: average molecular weight 8,000, polyalkylene ether having a hydrolyzable silicon functional group at a molecular chain terminal) as polyalkylene ether polymer (A) Polymer) was used.

Microcapsules (B) obtained by coating ammonium polyphosphate (phosphorus content 31.5% by weight, nitrogen content 14.5% by weight, decomposition temperature 275 ° C.) with a melamine resin by an interfacial polymerization method. Was used. The microcapsule (B) has a particle size of 1 to 100 μm,
The dissolution rate in water at 0 ° C. was 0.3% by weight or less.

Polyalkylene ether polymer (A) 10
0 parts by weight, 40 parts by weight of calcium carbonate, 10 parts by weight of titanium white, 75 parts by weight of microcapsules (B), 20 parts by weight of dipentaerythritol as polyhydric alcohol (C),
15 parts by weight of melamine as the amine group-containing compound (D),
50 parts by weight of dioctyl phthalate (DOP) as a plasticizer was stirred and mixed at room temperature until it became a paste. next,
The mixture was mixed well with three rolls to obtain a more uniform paste. 2 parts by weight of stannous octylate and 1 part by weight of laurylamine were added to this paste as a silanol compound condensation catalyst (E), and the mixture was stirred for 30 minutes under a nitrogen gas stream to obtain a fire-retardant composition.

Example 1 As shown in FIG. 1, the above-described fire-retardant composition was applied to one entire outer surface of a base material (U-shaped zinc steel sheet) 1 at 20 ° C.
It was left to dry in an atmosphere of 65% RH for 7 days to form a fire-resistant coating layer (thickness: 5 mm) 30. This fire protection coating layer 30
, Two exterior materials (12 mm thick fiber-containing fly ash slag cement board) 2 and 2 were attached so that the joint width became 10 mm. A fixed watertight material (made of EPDM rubber) 40 was press-fitted into the joint to seal.

Example 2 As shown in FIG. 2, a fixed watertight material (made of EPDM rubber) 41
The above-mentioned fire-retardant composition was applied to the side and bottom surfaces of the sample and inserted into joints to form a fire-retardant coating layer (dry thickness: 3 mm) 31. On one outer side of a base material (U-shaped zinc steel sheet) 1, two exterior materials (12 mm thick fiber-containing fly ash slag cement board) 2 and 2 were attached so as to have a joint width of 10 mm.
A standard watertight material 41 having a fire protection coating layer 31 formed at the joint.
Was press-fitted to seal.

Example 3 As shown in FIG. 3, two outer materials (12 mm thick fiber-containing fly ash slag cement board) 2 were provided on one outer surface of a base material (U-shaped zinc steel sheet) 2. 2 was attached so that the joint width might be 10 mm. The above composition for fire protection is applied to the joint bottom and inserted into the joint, and the fire protection coating layer (dry thickness 5 m
m) 32 was formed. A fixed watertight material (made of EPDM rubber) 42 was press-fitted onto the fire protection coating layer 32 to perform sealing.

-Comparative Example 1- As shown in FIG. 4, two exterior materials (12 mm thick fiber-containing fly ash slag cement board) 2 were provided on one outer surface of a base material (U-shaped zinc steel sheet) 2, 2 was attached so that the joint width might be 10 mm. A noncombustible material (asbestos foam made by Nichias Co., Ltd .: product name: Litoflex: thickness 5)
mm) 13 was inserted. A fixed watertight material (made of EPDM rubber) 14 was press-fitted onto the non-combustible material 13 to perform sealing.

The fireproof joints of the above Examples and Comparative Examples were subjected to a fireproof test and a watertightness test, and the results are shown in Table 1. The fire protection test was conducted according to Japanese Industrial Standard (JIS) A13.
02 "Fireproof test method for non-combustible structural parts of buildings". The water tightness test is based on Japanese Industrial Standards (JIS) A1517 "Water tightness test method for fittings"
And Japanese Industrial Standard A1414 "Performance test method for building components (panels) and their structural parts".

[0041]

[Table 1]

As shown in Table 1, each fire joint structure of the embodiment is superior in fire resistance and water tightness to that of the comparative example.

[0043]

According to the present invention, a fireproof joint structure having excellent watertightness and airtightness and also excellent fireproofness can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a first embodiment of a joint structure according to the present invention.

FIG. 2 is a schematic explanatory view showing a second embodiment of the joint structure according to the present invention.

FIG. 3 is a schematic explanatory view showing a third embodiment of the joint structure according to the present invention.

FIG. 4 is a schematic explanatory view showing a joint structure provided with a conventional fire prevention measure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base material 2 Exterior material 30 Fire protection coating layer 31 Fire protection coating layer 32 Fire protection coating layer 40 Standard watertight material 41 Standard watertight material 42 Standard watertight material

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroshi Iizuka 3-7-1 Nishiura, Funabashi-shi, Chiba Pref. Mitsui Kinzoku Paint Chemical Co., Ltd. (56) References JP-A-3-31379 (JP, A) ( 58) Field surveyed (Int. Cl. ⁷ , DB name) C09D 1/00-201/10 WPI (DIALOG)

Claims (4)

(57) [Claims] 1. A joint structure in which a sealing material is inserted into a joint between an exterior material and / or an interior material attached on a base material, wherein the surface of the base material, the exterior material and And / or at least one of the end surface of the interior material and the surface of the sealing material, the following component (A):
(B) A fireproof joint structure comprising a fireproof coating layer comprising a fireproofing composition containing (C), (D) and (E). (A) Polyalkylene ether polymer 10 having a hydrolyzable silicon functional group represented by the following formula 1 at a molecular chain terminal:
0 parts by weight. Embedded image (B) 20 to 150 parts by weight of microcapsules obtained by coating ammonium polyphosphate powder with a resin and having a solubility in water at 20 ° C. of 0.3% by weight or less. (C) 15 to 75 parts by weight of a polyhydric alcohol. (D) 5 to 50 parts by weight of an amino group-containing compound which generates a gas containing a nitrogen atom upon heating. (E) 0.1 to 10 parts by weight of a silanol compound condensation catalyst. 2. The fireproof joint structure according to claim 1, wherein the fireproof coating layer is formed on the surface of the base material at the joint bottom. 3. A fire-retardant coating layer is formed on the surface of the base material, an exterior material is mounted on the base material via the fire-retardant coating layer, and the fire-retardant coating layer faces the joint floor. The fire joint structure according to claim 2, wherein 4. The sealing material according to claim 1, wherein the sealing material is a fixed watertight material, and the fire-resistant coating layer is formed on a portion of the surface of the fixed watertight material inserted into the joint. Fire joint structure.