JP2012006986A - Room-temperature curable organopolysiloxane composition, thermal foaming fire-resistant coating material, and fire-resistant structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a room-temperature curable organopolysiloxane composition which is excellent in weather resistance, can sufficiently foam in a heating test using a standard heating curve conforming to ISO834, is excellent in adhesiveness with an iron frame substrate, can form a foaming layer which does not generate cracks reaching the substrate, and can impart a curable material also excellent in the adhesiveness with the substrate before the foaming; to provide a thermal foaming fire-resistant coating material which is composed of the composition and excellent in weather resistance; and to provide a fire-resistant structure in which the coating material is coated on a base material.SOLUTION: The room-temperature curable organopolysiloxane composition is characterized by containing: (A) 100 pts.mass of diorganopolysiloxane having hydroxyl groups at both terminal ends; (B) 10 to 50 pts.mass of an organosiloxane resin; (C) 10 to 100 pts.mass of a foaming agent; (D) 10 to 100 pts.mass of a hydrophobic treatment magnesium oxide and/or a hydrophobic calcium oxide; and (E) 1 to 20 pts.mass of an organic silicide compound having three of more hydrolytic groups coupled to silicide atoms in one molecule.

Description

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

  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 1-3).

  Among these synthetic resins, those other than silicone resins have a problem of insufficient weather resistance. When the synthetic resin is an organopolysiloxane, the one dissolved in an organic solvent or the emulsion is difficult to decompose structurally and has excellent weather resistance, but has poor adhesion and stability, and the coating film The weather resistance itself is 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) (nonpatent literature 1) However, there is almost no change in rubber physical properties and adhesiveness until 10 years outdoors exposure and 5,000 hours 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.

  In order to solve these problems, the present inventor complies with ISO834 by adding expansive graphite and organosiloxane resin to a curable organopolysiloxane composition excellent in durability, heat resistance, weather resistance and the like. In a heating test using a standard heating curve, it was found that a foamed layer that is sufficiently foamed and has excellent adhesion to a steel substrate and that has excellent adhesion to the substrate before foaming can be obtained. No. 2010-59298: Patent Document 4).

  However, in this composition, there was a case where a crack reaching the base reached the foam depending on the shape of the base. It was suggested that the thermal insulation, which is the purpose of this application, may be impaired when cracks that reach the substrate occur.

JP 2001-164194 A JP-A-10-110121 JP 2002-309183 A JP 2010-59298 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, and is excellent in weather resistance, sufficiently foamed in a heating test according to a standard heating curve according to ISO 834, and excellent in adhesion to a steel base, and has cracks reaching the base. A room temperature-curable organopolysiloxane composition that can form a foamed layer that does not occur, and gives a cured product that is also excellent in adhesion to the base before foaming, and a thermal foaming property that is excellent in weather resistance comprising the composition An object of the present invention is to provide a fireproof covering material and a fireproof structure in which the covering material is applied to a base material.

  As a result of intensive studies to achieve the above object, the present inventor has made a curable organopolysiloxane composition with a foaming agent and an organosiloxane resin, as well as a hydrophobically treated magnesium oxide and / or a hydrophobically treated oxidized material as a crack preventing agent. By adding calcium, it is possible to form a foamed layer that is sufficiently foamed in a heating test according to a standard heating curve in accordance with ISO834 and that has excellent adhesion to a steel base and does not cause cracks reaching the base, As a result, it was found that a composition capable of maintaining heat insulation and having excellent adhesion to the base before foaming was obtained, and the present invention was achieved.

Accordingly, the present invention provides a room temperature curable organopolysiloxane composition, a heat-foaming fire-resistant coating material, and a fire-resistant structure shown 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) Foaming agent: 10 to 100 parts by mass,
(D) Hydrophobic-treated magnesium oxide and / or hydrophobic-treated calcium oxide: 10 to 100 parts by mass,
(E) Organosilicon compound having at least three hydrolyzable groups bonded to silicon atoms in one molecule: 1 to 20 parts by mass A room temperature-curable organopolysiloxane composition characterized by comprising:
[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 curable composition according to claim 1, wherein the component (C) is expandable graphite and / or unexpanded microballoons.
[Claim 4]
The room temperature curable organo of claim 1, 2 or 3, further comprising 10 to 100 parts by mass of (F) a hydrophobically treated flame retardant other than component (D) with respect to 100 parts by mass of component (A). Polysiloxane composition.
[Claim 5]
(F) The room temperature-curable organopolysiloxane composition according to claim 4, wherein the hydrophobically treated flame retardant is an ammonium phosphate and / or an ammonium polyphosphate having a hydrophobic surface.
[Claim 6]
A heat-foamable fireproof coating material comprising the room temperature-curable organopolysiloxane composition according to any one of claims 1 to 5.
[Claim 7]
A structure in which the heat-foamable fire-resistant coating material according to claim 6 is applied to a substrate, and when applied to heat, the applied coating film foams to form a heat insulating layer. Fireproof structure.

  According to the room temperature curable organopolysiloxane composition of the present invention, it is excellent in weather resistance, sufficiently foamed in a heating test according to a standard heating curve according to ISO834, and excellent in adhesion to a steel base, and reaches the base. A foamed layer that does not cause cracks can be formed, whereby a heat-foaming fire-resistant coating material that can maintain heat insulation properties and is excellent in weather resistance that is also excellent in adhesion to a base before foaming is obtained.

[(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. A methyl group, a vinyl group, and a phenyl group are preferable.

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, in particular 0.7 to 1.1. If the molar ratio is too small or too large, flame retardancy and adhesion may be insufficient.

  The content of the hydroxysilyl group is preferably small, 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 the hydroxysilyl group is too large, the stability of the composition may be lowered.

  Such a copolymer is a material known in the art obtained by cohydrolyzing and condensing a hydrolyzable triorganosilane and 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)]
The foaming agent of component (C) is the most important element of the present invention, and is a component necessary for the present composition to sufficiently foam and obtain adhesion with the base. The component (C) is not particularly limited as long as the composition can be foamed, but expandable graphite and unexpanded microballoons are preferable, and expandable graphite is particularly preferable.

  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.

  The unexpanded microballoon has an outer shell made of a thermoplastic resin such as vinylidene chloride / acrylonitrile copolymer, methyl methacrylate / acrylonitrile copolymer, methacrylonitrile / acrylonitrile copolymer, and contains a volatile substance inside. It expands with heat. The particle diameter is preferably 1 to 50 μm.

  (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 (D) component hydrophobically treated magnesium oxide and / or hydrophobically treated calcium oxide improves flame retardancy in the composition of the present invention. The component (D) may be magnesium oxide or calcium oxide whose surface is hydrophobized, and is treated with an organic silicon compound such as silane, siloxane or silazane, or an inorganic powder such as silica whose surface is hydrophobized. In particular, those that have been subjected to a hydrophobic treatment with surface-hydrophobic fumed silica are preferred. The hydrophobization treatment suppresses the moisture content of the filler, 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 magnesium oxide particles or calcium oxide particles by a high-speed stirring means using a mixer such as a machine.

  (D) It is preferable that the average particle diameter of a component is 5-50 micrometers, More preferably, it is 5-30 micrometers. In the present invention, the average particle diameter can be determined, for example, as a weight average value (or median diameter) by a laser light diffraction method.

  (D) 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. When the blending amount is less than 10 parts by mass, the foam layer is not sufficiently integrated, and cracks reaching the base occur, and when it exceeds 100 parts by mass, the foam layer becomes too hard or the foam amount is insufficient. It becomes.

[(E) component]
The organosilicon compound (silane and / or siloxane) having at least three hydrolyzable groups bonded to a silicon atom in one molecule of the component (E) 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. Examples of organic groups other than hydrolyzable groups include alkyl groups such as methyl group, ethyl group, and propyl group, alkenyl groups such as vinyl group, and aryl groups such as phenyl group. Alkyl groups, vinyl groups and phenyl groups are preferred.

Specific examples of the component (E) include tetrakis (methylethylketoxime) silane, methyltris (dimethylketoxime) silane, methyltris (methylethylketoxime) silane, ethyltris (methylethylketoxime) silane, methyltris (methylisobutylketoxime) silane, vinyltris ( Ketoxime silanes such as methyl ethyl ketoxime) silane, ketoxime silanes such as vinyl tributanoxime silane, methyl tributanoxime silane, and methyltrimethoxysilane, vinyltrimethoxysilane, phenyltrimethoxysilane, vinyltriethoxysilane, etc. Alkoxysilanes, methyltriacetoxysilane, acetoxysilanes such as vinyltriacetoxysilane, methyltriisopropenoxy Orchids, vinyltriisopropenoxysilane, isopropenoxysilane silanes such as phenyltrimethoxysilane isopropenoxysilane silane, and partial hydrolytic condensates of these silanes. These may be used alone or in combination.
In addition, (E) component is a crosslinking agent, and the silane cup which has organic functional groups, such as an amino group, an epoxy group, (meth) acryloxy group, a mercapto group, which is (H) component which is an adhesion | attachment imparting agent mentioned later Ring agent is not included.

  (E) 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 blending 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, and if it exceeds 20 parts by mass, it is disadvantageous in price.

[(F) component]
It is preferable that the composition of the present invention contains a hydrophobically treated flame retardant (F) other than the component (D). 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.

  (F) 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.

[(G) component]
Moreover, it is preferable to mix | blend (G) a curing catalyst with the composition of this invention. The curing catalyst acts as a catalyst for the reaction of the components (A) and (E) 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, hexylamine, dodecylamine phosphate, tet Amine compounds such as methylguanidine and diazabicyclononane and their salts, quaternary ammonium salts such as benzyltriethylammonium acetate, lower fatty acid salts of alkali metals such as potassium acetate, sodium acetate and lithium oxalate, dimethylhydroxylamine, diethylhydroxyl Examples thereof include dialkylhydroxylamines such as amines. In particular, tin ester compounds and alkyltin ester compounds are 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.

[(H) component]
Moreover, it is preferable to mix | blend (H) 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, and have an amino group, an epoxy group, a (meth) acryloxy group, a mercapto group, etc. as an organic functional group, and an alkoxy group as a hydrolyzable group. The silane coupling agent having these hydrolyzable groups is preferably γ-methacryloxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxy. Examples include silane, γ-glycidoxypropylmethyldiethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, and the like. 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 blending amount is too small, sufficient adhesiveness may not be obtained. If the blending amount is too large, the blending effect will not be improved, which is disadvantageous in price.

[Other ingredients]
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, fillers such as fumed silica, calcium carbonate, aluminum hydroxide, titanium oxide, alumina, polyhydric alcohols such as pentaerythritol, dipentaerythritol, and tripentaerythritol, and additives include dimethyl as a plasticizer Silicone oils such as silicone oils, isoparaffins, etc., as necessary, may be added with appropriate amounts of thixotropic agents, pigments, dyes, coloring agents such as fluorescent brighteners, fungicides, antibacterial agents, etc. .

  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 fire-resistant structure in which the heat-foamable fire-resistant coating material is applied to a base material is such that, when exposed to heat, the applied coating film foams to form a heat insulating layer.

  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.

  The present invention will be described below with reference to the following examples and comparative examples, but the present invention is not limited to the following examples. 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 Treated with 20 parts by mass of organosiloxane resin having a content of 0.05%, 20 parts by mass of expanded graphite, 30 parts by mass of ammonium polyphosphate treated with surface dimethyldichlorosilane-treated fumed silica, and surface dimethyldichlorosilane-treated fumed silica 20 parts by mass of magnesium oxide, 10 parts by mass of fumed silica whose surface was treated with dimethyldichlorosilane, vinyl tributa Composition 1 was prepared by mixing 5 parts by mass of noxime silane, 5 parts by mass of methyltributanoxime silane, 0.15 parts by mass of dibutyltin dioctoate and 1 part by mass of γ-aminopropyltriethoxysilane until uniform. Prepared.

[Example 2]
In Example 1, Composition 2 was prepared in the same manner as in Example 1 except that the amount of magnesium oxide treated with surface dimethyldichlorosilane-treated fumed silica 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 expanded graphite 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]
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 Treated with 20 parts by mass of organosiloxane resin having a content of 0.05%, 20 parts by mass of expanded graphite, 30 parts by mass of ammonium polyphosphate treated with surface dimethyldichlorosilane-treated fumed silica, and surface dimethyldichlorosilane-treated fumed silica 20 parts by mass of magnesium oxide, 10 parts by mass of fumed silica whose surface was treated with dimethyldichlorosilane, vinyl trimeth Composition 5 was prepared by mixing 5 parts by mass of xylsilane and 3 parts by mass of dipropoxybis (acetylacetona) titanium until uniform under dry conditions.

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

[Comparative Example 2]
In Example 1, Composition 7 was prepared in the same manner as in Example 1 except that the amount of magnesium oxide treated with surface dimethyldichlorosilane-treated fumed silica was changed to 110 parts by mass instead of 20 parts by mass.

  The compositions of the examples and comparative examples (foamable fire-resistant paint) are applied to H-shaped steel and subjected to a heating test with a cured specimen, and the foaming ratio, the appearance after heating, the adhesion with the substrate, and the resistance to resistance. The cracking property (whether the foamed layer is integrated as a means for evaluating whether or not the base has been reached when a crack occurs) was confirmed.

  In the evaluation test, the foamed refractory paints of Examples and Comparative Examples were applied with a spatula to a thickness of 2 to 3 mm on a blasted and degreased 100 mm × 100 mm × 5 to 7 mm thick H-shaped steel, and cured for 7 days. Thus, a test body was produced. These specimens were subjected to a heating test according to a standard heating curve in accordance with ISO834 to measure the expansion ratio, and after the test (appearance, adhesion, crack resistance) 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

<Crack resistance>: The crack resistance was evaluated by visually observing the occurrence of cracks in which the foam layers were integrated and reached the base.
○: No crack occurred △: Small crack occurred ×: Large crack occurred

＊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 (7)

(A) Diorganopolysiloxane having hydroxyl groups at both ends: 100 parts by mass,
(B) Organosiloxane resin: 10 to 50 parts by mass,
(C) Foaming agent: 10 to 100 parts by mass,
(D) Hydrophobic-treated magnesium oxide and / or hydrophobic-treated calcium oxide: 10 to 100 parts by mass,
(E) Organosilicon compound having at least three hydrolyzable groups bonded to silicon atoms in one molecule: 1 to 20 parts by mass A room temperature-curable organopolysiloxane composition characterized by comprising: 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 curable composition according to claim 1, wherein the component (C) is expandable graphite and / or unexpanded microballoons.   The room temperature curable organo of claim 1, 2 or 3, further comprising 10 to 100 parts by mass of (F) a hydrophobically treated flame retardant other than component (D) with respect to 100 parts by mass of component (A). Polysiloxane composition.   (F) The room temperature-curable organopolysiloxane composition according to claim 4, wherein 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 5.   A structure in which the heat-foamable fire-resistant coating material according to claim 6 is applied to a substrate, and when applied to heat, the applied coating film foams to form a heat insulating layer. Fireproof structure.