JP2010059298A - Room-temperature curing organopolysiloxane composition and heat foaming fire-resistant coating material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a room-temperature curing organopolysiloxane composition having excellent weatherability, satisfactorily foaming in a heating test by a standard heating curve according to ISO 834, forming a foaming layer having excellent adhesiveness to a steel frame underlayer and giving a cured product having excellent adhesiveness to an underlayer before foaming and to provide a heat foaming fire-resistant coating material including the composition and having excellent weatherability. <P>SOLUTION: The room-temperature curing organopolysiloxane composition includes (A) a diorganopolysiloxane having hydroxyl groups at both ends: 100 pts.mass, (B) an organosiloxane resin: 10 to 50 pts.mass, (C) an expansive graphite: 10 to 100 pts.mass and (D) an organic silicon compound having at least three hydrolyzable groups bonded to a silicon atom in one molecule: 1 to 20 pts.mass. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a room temperature which can be a heat-foaming fire-resistant paint that is applied as a thin film to steel materials used for steel columns, beams, etc. and foams when exposed to heat such as in a fire to form a heat insulating layer. The present invention relates to a curable organopolysiloxane composition and a heat-foaming fire-resistant coating material made of the composition and excellent in weather resistance.

  Conventionally, various heat-foamable fireproof paints are known. As components of these heat-foaming fire-resistant paints, in most cases, a flame retardant foaming agent, a polyhydric alcohol as a carbonized layer forming agent, etc., as a synthetic resin serving as a coating film adhesion and weather resistance at normal temperature The synthetic resin is dissolved in an organic solvent or dispersed in water as an emulsion (for example, JP-A No. 2001-164194, JP-A No. 10-110121, JP 2002-309183 A: Patent documents 1 to 3).

  Among these synthetic resins, those other than silicone resins have a problem of insufficient weather resistance. When the synthetic resin is an organopolysiloxane, those dissolved in organic solvents or emulsions are difficult to decompose and have excellent weather resistance, but are poor in adhesion and stability, and the weather resistance of the coating itself. The property is also inferior. In addition, as a weather resistance performance of a curable composition, the weather resistance of a condensation-type sealing material is "the sealing material for construction-the foundation and the right usage-" (Japan Sealing Material Industries Association, 2nd edition): Although it is listed, it has been shown that there is almost no change in rubber physical properties and adhesiveness until 10 years of outdoor exposure and 5,000 hours of accelerated exposure.

  On the other hand, the fire-resistant paints used so far often had little solar radiation indoors or outdoors, so it was rarely required to have weather resistance and was not a problem. The demand for is growing. Specifically, this is an increase in demand for fireproof paints for buildings, such as steel structures that are exposed to sunlight outdoors. However, in order to use the conventional product for such applications, it is necessary to take measures such as making the topcoat layer a fluororesin type in consideration of the weather resistance, so that the cost increases, and an expensive topcoat layer is required. There has been a demand for a heat-foaming fire-resistant coating material having high weather resistance that is not required.

JP 2001-164194 A JP-A-10-110121 JP 2002-309183 A “Sealant for Architecture-Basics and Correct Usage” (Japan Sealant Industry Association, 2nd edition)

  The present invention has been made in view of the above circumstances, is excellent in weather resistance, sufficiently foamed in a heating test according to a standard heating curve in accordance with ISO 834, and forms a foamed layer excellent in adhesion to a steel base, It is an object of the present invention to provide a room temperature-curable organopolysiloxane composition that gives a cured product that is also excellent in adhesion to a base before foaming, and a heat-foaming fire-resistant coating material that is excellent in weather resistance.

  As a result of intensive studies to achieve the above object, the present inventors have added expansive graphite and an organosiloxane resin to a curable organopolysiloxane that is inherently excellent in durability, heat resistance, weather resistance, etc. Thus, in the heating test according to the standard heating curve in accordance with ISO834, a foamed layer that is sufficiently foamed and excellent in adhesion to the steel base is formed, and a composition excellent in adhesion to the base before foaming is obtained. As a result, the inventors have made the present invention.

Accordingly, the present invention provides a room temperature curable organopolysiloxane composition and a heat-foamable fireproof coating material described below.
[Claim 1]
(A) Diorganopolysiloxane having hydroxyl groups at both ends: 100 parts by mass,
(B) Organosiloxane resin: 10 to 50 parts by mass,
(C) Expandable graphite: 10 to 100 parts by mass,
(D) Organosilicon compound having 1 to 20 parts by mass of an organosilicon compound having at least three hydrolyzable groups bonded to a silicon atom in one molecule.
[Claim 2]
Component (B) is composed of R ′ ₃ SiO _1/2 units (wherein each R ′ independently represents an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms) and SiO _4/2 units. The molar ratio of R ′ ₃ SiO _1/2 units to SiO _4/2 units is 0.6 to 1.2, and the hydroxysilyl group content is 0 to 0.15 mol / 100 g. A room temperature curable organopolysiloxane composition.
[Claim 3]
The room temperature-curable organopolysiloxane composition according to claim 1, further comprising (E) a hydrophobically treated flame retardant.
[Claim 4]
4. The room temperature curable organopolysiloxane composition according to claim 3, wherein (E) the hydrophobically treated flame retardant is an ammonium phosphate and / or an ammonium polyphosphate having a hydrophobic surface.
[Claim 5]
A heat-foamable fireproof coating material comprising the room temperature-curable organopolysiloxane composition according to any one of claims 1 to 4.

  According to the room temperature-curable organopolysiloxane composition of the present invention, a foamed layer having excellent weather resistance, sufficiently foaming in a heating test according to a standard heating curve in accordance with ISO834, and excellent in adhesion to a steel base is formed. In addition, a heat-foaming fire-resistant coating material having excellent weather resistance and excellent adhesion to the base before foaming can be obtained.

The heat-foamable fireproof coating material of the present invention is
(A) a diorganopolysiloxane having hydroxyl groups at both ends,
(B) an organosiloxane resin,
(C) containing expandable graphite, and (D) an organosilicon compound having at least three hydrolyzable groups bonded to a silicon atom in one molecule,
(E) It consists of a room temperature curable organopolysiloxane composition containing a hydrophobically treated flame retardant.

[(A) component]
The diorganopolysiloxane having a hydroxyl group at both ends of the component (A) is used as a base polymer of the composition, and as the component, one represented by the following general formula (1) can be used. .
HO— (R ₂ SiO) _k —H (1)
(In the formula, R is the same or different unsubstituted or substituted monovalent hydrocarbon group, and k is an integer of 10 or more.)

  In the above formula (1), R is independently an alkyl group such as methyl, ethyl, propyl, isopropyl or hexyl, a cycloalkyl group such as cyclohexyl, an alkenyl group such as vinyl, allyl or propenyl, and an aryl group such as phenyl. Such monovalent hydrocarbon groups having 1 to 6 carbon atoms, or a chloromethyl group or a 3,3,3-trifluoropropyl group in which part or all of the hydrogen atoms of these groups are substituted with a halogen atom or the like. A valent substituted hydrocarbon group is shown. A methyl group, a vinyl group, a phenyl group, and a 3,3,3-trifluoropropyl group are preferable, and a methyl group is particularly preferable.

  k is an integer of 10 or more, and the viscosity of the diorganopolysiloxane at 25 ° C. is preferably a number that is 100 to 1,000,000 mPa · s, more preferably 500 to 100,000 mPa · s. . If the viscosity is too low, the physical properties of the resulting cured product may be insufficient, and if it is too high, the workability of the composition may be reduced. The viscosity can be measured with a rotational viscometer.

  Such a diorganopolysiloxane is a material known in the art obtained by, for example, equilibrating a corresponding cyclic siloxane in the presence of water.

[Component (B)]
The (B) component organosiloxane resin is an important element of the present invention, and is a necessary component for obtaining adhesion between the composition and the substrate. The organosiloxane resin is preferably a branched organopolysiloxane, and R ′ ₃ SiO _1/2 units (wherein each R ′ is independently an unsubstituted or substituted monovalent hydrocarbon having 1 to 6 carbon atoms). Group) and SiO _4/2 units, and the molar ratio of R ′ ₃ SiO _1/2 units to SiO _4/2 units (R ′ ₃ SiO _1/2 / SiO _4/2 ) is 0.6 to 1. 2 and an organosiloxane resin containing 0 to 0.15 mol / 100 g of hydroxysilyl groups, which is a resinous organosiloxane copolymer. Usually, it is used as a solution of an organic solvent such as toluene and xylene, but in the present invention, it is preferable not to contain an organic solvent in order to prevent sick house and to eliminate the solvent, and the content of the organic solvent is the component (B). In the organosiloxane resin, it is preferably 0.5% by mass or less, particularly preferably 0.1% by mass or less.

Here, each R ′ is independently an alkyl group such as methyl, ethyl, propyl, isopropyl or hexyl, a cycloalkyl group such as cyclohexyl, an alkenyl group such as vinyl, allyl or propenyl, and an aryl group such as phenyl. Monovalent hydrocarbon groups having 1 to 6 carbon atoms, or monovalent hydrocarbon groups such as chloromethyl groups and 3,3,3-trifluoropropyl groups in which some or all of the hydrogen atoms are substituted with halogen atoms or the like Of the substituted hydrocarbon group.
Preferred are a methyl group, a vinyl group, and a phenyl group, and particularly preferred are a methyl group and a vinyl group.

The organosiloxane resin comprising the R ′ ₃ SiO _1/2 unit and the SiO _4/2 unit is preferably a molar ratio of the R ′ ₃ SiO _1/2 unit (b) to the SiO _4/2 unit (a) [( b) / (a)] is 0.6 to 1.2. If the molar ratio is too small or too large, flame retardancy may be insufficient.

  The content of hydroxysilyl group is preferably 0 to 0.15 mol / 100 g, more preferably 0 to 0.10 mol / 100 g, and particularly preferably 0 to 0.08 mol / 100 g. If the amount of hydroxysilyl group is too large, flame retardancy may be insufficient.

  Such a copolymer is a material known in the art obtained by cohydrolyzing and condensing a hydrolyzable triorganosilane, a hydrolyzable silane not containing an R group, and a siloxane.

Note that the organosiloxane resin is within a range not to impair the effect, R'SiO _3/2 units, R _'2 and SiO _2/2 units in total R' ₃ and SiO _1/2 units and SiO _4/2 units You may contain in the ratio of 10 mol% or less with respect to a total, especially 5 mol% or less.

  (B) The compounding quantity of a component is 10-50 mass parts with respect to 100 mass parts of said (A) component, Preferably it is 15-40 mass parts, Most preferably, it is 20-35 mass parts. Adhesiveness will become inadequate when the said compounding quantity is less than 10 mass parts, and the preservability as a composition will fall when it exceeds 50 mass parts.

[Component (C)]
Component (C), expandable graphite, is the most important element of the present invention, and is a component necessary for the composition to sufficiently foam and obtain adhesion to the substrate.

  Expandable graphite has the property that when heated, the compound present between the graphite layers decomposes to generate gas and the whole expands. In the present invention, it is preferable to use a type in which impurities of natural flake graphite are removed to the limit and treated with a sulfide system, a nitrogen system, an organic acid system or the like. There are various grades of expansive graphite depending on the expansion start temperature, particle diameter, expansion coefficient, etc. In the present composition, the expansion start temperature is 130 to 320 ° C. in order to effectively achieve the object of the present invention. The particle diameter is preferably 45 to 500 μm and the expansion volume is preferably 50 to 300 ml / g. Particularly, the expansion start temperature is 130 to 320 ° C., the particle diameter is 150 to 180 μm, and the expansion volume is 100 to 250 ml / g. It is preferable. Moreover, sodium graphite, potassium graphite, etc. can also be used.

  (C) The compounding quantity of a component is 10-100 mass parts with respect to 100 mass parts of said (A) component, Preferably it is 30-60 mass parts. If the blending amount is less than 10 parts by mass, the foaming amount and adhesion may be insufficient, and if it exceeds 100 parts by mass, the foaming amount may be too large and the foamed layer may become unstable. Disadvantageous.

[(D) component]
The organosilicon compound (silane and / or siloxane) having at least three hydrolyzable groups bonded to a silicon atom in one molecule of component (D) acts as a storage stabilizer and a crosslinking agent in the composition of the present invention. To do. Examples of the hydrolyzable group possessed by the organosilicon compound include a ketoxime group, an alkoxy group, an acetoxy group, and an isopropenoxy group. Specific examples of organosilicon compounds include tetrakis (methyl ethyl ketoxime) silane, methyl tris (dimethyl ketoxime) silane, methyl tris (methyl ethyl ketoxime) silane, ethyl tris (methyl ethyl ketoxime) silane, methyl tris (methyl isobutyl ketoxime) silane, vinyl tris (methyl ethyl keto). Oxime) ketoxime silanes such as silane, and alkoxy silanes such as methyl trimethoxy silane, vinyl trimethoxy silane, phenyl trimethoxy silane, vinyl triethoxy silane, acetoxy silanes such as methyl triacetoxy silane, vinyl triacetoxy silane , Methyl triisopropenoxy silane, vinyl triisopropenoxy silane, phenyl triisopropenoxy silane, etc. Isopropenoxysilane silanes and partial hydrolytic condensates of these silanes. These may be used alone or in combination.

  (D) The compounding quantity of a component is 1-20 mass parts with respect to 100 mass parts of (A) component, Preferably it is 5-15 mass parts. If the amount is less than 1 part by mass, sufficient crosslinking cannot be obtained, and it is difficult to obtain a target composition having rubber elasticity. If the amount exceeds 20 parts by mass, it is disadvantageous in price.

  The composition of the present invention preferably contains a hydrophobically treated flame retardant (E) other than the expandable graphite (C). The hydrophobic flame retardant is not particularly limited as long as the surface is a hydrophobic flame retardant, and a known flame retardant can be used, but ammonium phosphate and / or ammonium polyphosphate is preferable, and surface hydrophobicity is particularly preferable. Those that have been hydrophobized with fumed silica are preferred. The hydrophobizing treatment suppresses the moisture content of the flame retardant, and this is necessary for improving the water resistance of the coating film and stabilizing the storage stability of the condensation compound. The treatment method may be a known method such as surface treatment with an organosilicon compound such as silane or siloxane, and the treatment with surface hydrophobic fumed silica is performed by ball mill, V-type mixer, ribbon-type mixer, screw mixing. Hydrophobic fumed silica is coated on the surface of ammonium phosphate or ammonium polyphosphate particles by a high-speed stirring means using a mixer such as a machine.

  (E) It is preferable that the compounding quantity in the case of mix | blending a component is 10-100 mass parts with respect to 100 mass parts of said (A) component, More preferably, it is 20-80 mass parts, Most preferably, it is 30-65. Part by mass. If the blending amount is too small, the adhesion may be insufficient, and if it is too large, the foam layer may be too hard.

[Other ingredients]
Moreover, it is preferable to mix | blend (F) curing catalyst with the composition of this invention. The curing catalyst acts as a catalyst for the reaction of the components (A) and (D) and the curing reaction by hydrolysis of the composition in the composition of the present invention. Specific examples of the curing catalyst include tin ester compounds such as dioctate tin, alkyltin ester compounds such as dibutyltin diacetate, dibutyltin dilaurate, and dibutyltin dioctoate, tetraisopropoxy titanium, tetra n-butoxy titanium, tetrakis (2 -Ethylhexoxy) titanium, dipropoxy bis (acetylacetona) titanium, titanium isopropoxy octylene glycol, etc. titanate ester or titanium chelate compound, zinc naphthenate, zinc stearate, zinc-2-ethyl octoate, iron-2 -Organometallic compounds such as ethylhexoate, cobalt-2-ethylhexoate, manganese-2-ethylhexoate, cobalt naphthenate, alkoxyaluminum compound, 3-aminopropyltriethoxysilane, N- (Aminoethyl) aminoalkyl group-substituted alkoxysilanes such as γ-aminopropyltrimethoxysilane, amine compounds such as hexylamine, dodecylamine phosphate, tetramethylguanidine, diazabicyclononane and salts thereof, benzyltriethylammonium acetate, etc. Quaternary ammonium salts, lower fatty acid salts of alkali metals such as potassium acetate, sodium acetate and lithium oxalate, dialkylhydroxylamines such as dimethylhydroxylamine and diethylhydroxylamine, tetramethylguanidylpropyltrimethoxysilane, tetramethylguani Examples include silanes or siloxanes containing guanidyl groups such as dipropylpropylmethyldimethoxysilane and tetramethylguanidylpropyltris (trimethylsiloxy) silane. Tin ester compounds, alkyltin ester compound is preferably used. These are not limited to one kind, and may be used as a mixture of two or more kinds.

  In addition, although the compounding quantity in the case of mix | blending these curing catalysts may be a catalyst amount, 0.01-10 mass parts with respect to 100 mass parts of (A) component, Especially 0.05-5 mass parts is preferable.

  Moreover, it is preferable to mix | blend (G) silane coupling agent with the composition of this invention. The silane coupling agent is a component that improves adhesion imparting in the composition of the present invention. As the silane coupling agent, known ones are preferably used, but those having an alkoxysilyl or alkenoxysilyl group as the hydrolyzable group are preferred, and as the silane coupling agent having these hydrolyzable groups, Vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyl Diethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-glycidoxypropyltriisopropenoxysilane, γ-glycine Sidoxypropyl methyl diisopro Examples include penoxysilane. In particular, the use of an amine-based silane coupling agent is preferred.

  0.1-20 mass parts is preferable per 100 mass parts of (A) component, and, as for the compounding quantity in the case of mix | blending this silane coupling agent, More preferably, it is 0.2-10 mass parts. If the amount is less than 0.1 parts by mass, a sufficient blending effect (adhesiveness) may not be obtained. If the amount exceeds 20 parts by mass, the blending effect will not be improved, which may be disadvantageous in price.

  In addition, as long as the effects of the present invention are not impaired, generally known fillers and additives other than the above components may be used in the composition of the present invention. Specifically, as fumed silica, calcium carbonate, unexpanded microballoons, fillers such as aluminum hydroxide, titanium oxide, alumina, polyhydric alcohols such as pentaerythritol, dipentaerythritol, tripentaerythritol, additives Does not contain any appropriate amounts of silicone oil, isoparaffin, etc. as plasticizers, such as thixotropic agents, pigments, dyes, coloring agents such as fluorescent brighteners, fungicides, antibacterial agents, etc. There is no problem.

  The composition of the present invention can be prepared by uniformly mixing the above-described components under dry conditions according to a conventional method.

  The obtained composition can be suitably used as a heat-foaming fireproof covering material, and can be applied to, for example, a part to be a fireproof structure in a structure such as a building or a civil engineering structure. , Floors, beams, roofs, stairs, etc. Most of these parts are made of base materials such as concrete and metal, but can be applied not only to concrete and metal, but also to base materials such as wood and resin. It is. In addition, since the heat-foamable fireproof covering material of this invention has weather resistance, it can be used also for what has sunlight, such as the outdoors.

  The heat-foamable fire-resistant coating material of the present invention can be applied and applied in the same manner as in the past, and the coating film can be appropriately selected, but usually has a thickness of 0.1 to 5 mm, particularly 1 to 3 mm. Are preferably used.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example. In addition, in the following example,% shows the mass% and a viscosity shows the value in 25 degreeC measured with the rotational viscometer.

[Example 1]
65 parts by mass of dimethylpolysiloxane having a hydroxyl group at both ends and a viscosity of 1,500 mPa · s, 15 parts by mass of dimethylpolysiloxane having both ends of a molecular chain having a viscosity of 50 mPa · s blocked with trimethylsiloxy groups, (CH ₃ ) ₃ SiO _1/2 unit and SiO _4/2 unit, (CH ₃ ) ₃ SiO _1/2 unit / SiO _4/2 unit (molar ratio) = 0.85, hydroxysilyl group 0.04 mol / 100 g, toluene 15 parts by mass of an organosiloxane resin having a content of 0.05%, 20 parts by mass of expanded graphite, 20 parts by mass of ammonium polyphosphate treated with surface dimethyldichlorosilane-treated fumed silica, and 10 parts by mass of surface dimethyldichlorosilane-treated fumed silica Parts, vinyl tributanoxime silane 5 parts by mass, methyl tributanoxime silane 5 parts by mass, dibutyltin dioctoate Composition 1 was prepared by mixing 0.15 parts by mass and 1 part by mass of γ-aminopropyltriethoxysilane until uniform under dry conditions.

[Example 2]
In Example 1, Composition 2 was prepared in the same manner as in Example 1 except that the amount of expanded graphite was changed to 40 parts by mass instead of 20 parts by mass.

[Example 3]
In Example 1, Composition 3 was prepared in the same manner as in Example 1 except that the amount of ammonium polyphosphate treated with surface dimethyldichlorosilane-treated fumed silica was changed to 40 parts by mass instead of 20 parts by mass. .

[Example 4]
In Example 1, Composition 4 was prepared in the same manner as in Example 1 except that 10 parts by mass of calcium carbonate was further added.

[Example 5]
In Example 1, the amount of expanded graphite was changed to 30 parts by mass instead of 20 parts by mass, and the composition was obtained in the same manner as in Example 1 except that ammonium polyphosphate treated with surface dimethyldichlorosilane-treated fumed silica was removed. Product 5 was prepared.

[Example 6]
In Example 1, Composition 6 was prepared in the same manner as in Example 1 except that the amount of ammonium polyphosphate treated with surface dimethyldichlorosilane-treated fumed silica was changed to 5 parts by mass instead of 20 parts by mass. .

[Example 7]
In Example 1, Composition 7 was prepared in the same manner as in Example 1 except that the amount of ammonium polyphosphate treated with surface dimethyldichlorosilane-treated fumed silica was changed to 110 parts by mass instead of 20 parts by mass. .

[Example 8]
65 parts by mass of dimethylpolysiloxane having a hydroxyl group at both ends and a viscosity of 1,500 mPa · s, 15 parts by mass of dimethylpolysiloxane having both ends of a molecular chain having a viscosity of 50 mPa · s blocked with trimethylsiloxy groups, (CH ₃ ) ₃ SiO _{It consists of 1/2} units and SiO _4/2 units, (CH ₃ ) ₃ SiO _1/2 units / SiO _4/2 units (molar ratio) = 0.85, hydroxysilyl group 0.04 mol / 100 g, toluene 15 parts by mass of an organosiloxane resin having a content of 0.05%, 20 parts by mass of expanded graphite, 20 parts by mass of ammonium polyphosphate treated with surface dimethyldichlorosilane-treated fumed silica, and 10 parts by mass of surface dimethyldichlorosilane-treated fumed silica Parts, 5 parts by weight of vinyltrimethoxysilane, 3 parts by weight of dipropoxybis (acetylacetona) titanium under dry conditions The composition 8 was prepared by mixing until

[Comparative Example 1]
In Example 1, composition 9 was prepared in the same manner as in Example 1 except that the amount of expanded graphite was changed to 5 parts by mass instead of 20 parts by mass.

[Comparative Example 2]
In Example 1, Composition 10 was prepared in the same manner as in Example 1 except that the amount of expanded graphite was changed to 110 parts by mass instead of 20 parts by mass.

[Comparative Example 3]
In Example 1, it _{consists of} (CH ₃ ) ₃ SiO _1/2 units and SiO _4/2 units, (CH ₃ ) ₃ SiO _1/2 units / SiO _4/2 units (molar ratio) = 0.85, hydroxy The composition was the same as in Example 1 except that the amount of the organosiloxane resin having a silyl group of 0.04 mol / 100 g and a toluene content of 0.05% was changed to 5 parts by mass instead of 15 parts by mass. 11 was prepared.

The compositions of the examples and comparative examples (foamable refractory paint) are applied to a box-shaped steel sheet and H-shaped steel, and subjected to a heat test using a cured specimen, and the expansion ratio, the appearance after heating, and the base The adhesion was confirmed.
In the evaluation test, 100 mm × 100 mm × 5 to 7 mm thick H-shaped steel and box-shaped steel plate subjected to blasting and degreasing treatment, and the foamed fireproof paints of Examples and Comparative Examples were applied to a thickness of 2 to 3 mm with a spatula. Cured for a day and cured to prepare a test specimen. These specimens were subjected to a heating test according to a standard heating curve in accordance with ISO834 to measure the expansion ratio, and the state (appearance and adhesion) after the test was confirmed and evaluated according to the following criteria. The results are shown in Tables 1 and 2.

<appearance>
◎: Good ○: Somewhat good △: Somewhat bad ×: Bad

<Adhesion>
○: Adhesion with the substrate is good Δ: Adhesion with the substrate is slightly bad ×: Adhesion with the substrate is poor

＊発泡層が必要な断熱性を有する発泡倍率を１０倍以上とした。

* The expansion ratio having heat insulation necessary for the foam layer was set to 10 times or more.

Claims (5)

(A) Diorganopolysiloxane having hydroxyl groups at both ends: 100 parts by mass,
(B) Organosiloxane resin: 10 to 50 parts by mass,
(C) Expandable graphite: 10 to 100 parts by mass,
(D) Organosilicon compound having 1 to 20 parts by mass of an organosilicon compound having at least three hydrolyzable groups bonded to a silicon atom in one molecule. Component (B) is composed of R ′ ₃ SiO _1/2 units (wherein each R ′ independently represents an unsubstituted or substituted monovalent hydrocarbon group having 1 to 6 carbon atoms) and SiO _4/2 units. The molar ratio of R ′ ₃ SiO _1/2 units to SiO _4/2 units is 0.6 to 1.2, and the hydroxysilyl group content is 0 to 0.15 mol / 100 g. A room temperature curable organopolysiloxane composition.   The room temperature-curable organopolysiloxane composition according to claim 1, further comprising (E) a hydrophobically treated flame retardant.   4. The room temperature curable organopolysiloxane composition according to claim 3, wherein (E) the hydrophobically treated flame retardant is an ammonium phosphate and / or an ammonium polyphosphate having a hydrophobic surface.   A heat-foamable fireproof coating material comprising the room temperature-curable organopolysiloxane composition according to any one of claims 1 to 4.