Heat-expandable fire-resistant urethane foam composition, method for producing heat-expandable fire-resistant urethane foam composition, and heat-expandable fire-resistant urethane foam joint material

Abstract

To provide a thermally expandable fire-resistant urethane foam composition with superior thermal expandability, post-thermal expansion morphological stability, and flexibility.SOLUTION: Provided is a thermally expandable fire-resistant urethane foam composition set forth in Claim 1, which contains 5-100 pts.mass of thermally expandable graphite and 0.5-30 pts.mass of sodium silicate relative to 100 pts.mass of a urethane compound.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat-expandable fire-resistant urethane foam composition, a method for producing the heat-expandable fire-resistant urethane foam composition, and a heat-expandable fire-resistant urethane foam joint material. The heat-expandable fire-resistant urethane foam joint material is used, for example, to fill all or part of the gaps in a penetration opening in a fire compartment, or between a seismic isolation device and a fire-resistant panel in a building, or at the end of the fire-resistant panel. [Background technology]

[0002] Fire-resistant expansive materials have been used as joint sealants between fire walls and cables such as power cables and communication cables, or piping for air conditioning equipment, that penetrate fire compartments. Fire-resistant expansive materials expand when heated during a fire to form an expansive layer, which seals the gaps at the penetration openings in the fire compartment and prevents the fire from spreading. Therefore, fire-resistant joint sealants made of fire-resistant expansive materials are required to be able to retain their shape for as long as possible, especially after the expansive layer is formed, without easily losing its shape due to the heat of the fire.

[0003] A method for producing fire-resistant polyurethane, an intumescent material with excellent elasticity and flexibility, has been disclosed (Patent Document 1). This method is characterized by blending polyol and polyisocyanate with expandable graphite as a flame retardant, and using powdered casein as a shape stabilizer.

[0004] Also, a fireproof joint material made of soft urethane foam, epoxy resin, and thermally expandable graphite has been disclosed (Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special table flat 03-504738 [Patent Document 2] Patent Publication No. 2006-070155 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, fire resistance is not just about making the material itself less flammable; it is also required to have the ability to prevent flames from reaching the back side of the component (for example, by expanding due to heat in the event of a fire, and closing gaps between the fire wall and power cables, etc., to prevent flames from entering), i.e., fire prevention performance.

[0007] Patent Documents 1 and 2 have a problem in that the shape stabilizing effect after expansion is lost when the temperature exceeds 300° C. On the other hand, flexibility is required to fill gaps such as joints.

[0008] The present invention overcomes the problems of the prior art and provides a heat-expandable fire-resistant urethane foam composition that is excellent in heat expandability, shape stability after heat expansion, and flexibility, a method for producing said heat-expandable fire-resistant urethane foam composition, and a heat-expandable fire-resistant urethane foam joint material made from said heat-expandable fire-resistant urethane foam composition. [Means for solving the problem]

[0009] As a result of extensive research, the present inventors have discovered that the above problems can be solved by preparing a heat-expandable fire-resistant urethane foam composition having a specific composition, and have thus completed the present invention.

[0010] That is, the present invention provides the following inventions. [1] A thermally expandable fire-resistant urethane foam composition comprising 5 to 100 parts by mass of thermally expandable graphite and 0.5 to 30 parts by mass of sodium silicate per 100 parts by mass of a urethane compound. [2] The thermally expandable fire-resistant urethane foam composition according to [1], wherein the urethane compound contains a urethane prepolymer or contains a structure derived from a urethane prepolymer. [3] The thermally expandable fire-resistant urethane foam composition according to [1] or [2], wherein the test piece is molded into a rectangular parallelepiped having dimensions of 30 mm width x 30 mm length x 10 mm height, and the Shore E hardness of the first and second surfaces of the 30 mm width x 30 mm length is measured in accordance with JIS K6253 under a load of 1 kg at 21°C. The Shore E hardness of the first surface and the Shore E hardness of the second surface are measured, and the absolute value of the difference in hardness expressed by the following formula is less than 5: Hardness difference = |(Shore E hardness of the first surface) - (Shore E hardness of the second surface)| [4] A method for producing a heat-expandable fire-resistant urethane foam composition according to any one of [1] to [3], comprising a step of blending an isocyanate compound with an aqueous sodium silicate solution in which heat-expandable graphite is dispersed. [5] A heat-expandable fire-resistant urethane foam joint material according to any one of [1] to [3], which is used as a fire-prevention joint material. [Effects of the Invention]

[0011] According to the present invention, a heat-expandable fire-resistant urethane foam composition having excellent thermal expandability, shape stability after thermal expansion, and flexibility can be obtained. When such a heat-expandable fire-resistant urethane foam composition is used as a joint material, excellent fire resistance can be expected. For example, such a heat-expandable fire-resistant urethane foam composition is flexible and can effectively fill gaps such as joints. In addition, in the event of a fire, the heat-expandable graphite forms an expanded layer, and the shape retention effect of the sodium silicate prevents the foam from becoming brittle even when exposed to high temperatures for a long period of time (e.g., 0.5 hours), and stable fire resistance can be expected. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating a method for cutting out a sample piece from a urethane foam composition in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0013] The following describes embodiments of the present invention. The various features shown in the following embodiments can be combined with each other. Furthermore, each feature can be an invention independently.

[0014] 1. Composition of thermally expandable urethane foam A thermally expandable urethane foam composition according to one embodiment of the present invention (hereinafter referred to as "urethane foam composition") contains a urethane compound, thermally expandable graphite, and sodium silicate.

[0015] <Urethane compounds> The urethane compound is a compound having a urethane bond. The urethane compound preferably forms a urethane foam (a foamed material). The urethane foam can be obtained, for example, by reacting a urethane raw material with a foaming agent. For example, carbon dioxide is generated by reacting the isocyanate group of the urethane raw material with water, which causes foaming to occur, resulting in the production of the urethane foam. The urethane foam preferably has an expansion ratio of 2 to 20 times and a density of 120 to 500 kg / m. 3 is.

[0016] The urethane raw material includes an isocyanate compound. The urethane compound includes an isocyanate compound or includes a structure derived from an isocyanate compound. The urethane compound preferably includes a urethane prepolymer or includes a structure derived from a urethane prepolymer.

[0017] <Isocyanate compounds> The isocyanate compound is, for example, a compound having two or more isocyanate groups. The isocyanate compound includes one or more compounds selected from the group consisting of polyisocyanates having two or more isocyanate groups, and polymers obtained by reacting polyols with excess polyisocyanates and having isocyanate groups at the molecular terminals (urethane prepolymers). The isocyanate compound is

[0018] The urethane raw material may contain a polyol in addition to an isocyanate compound. The urethane raw material may contain, for example, a polyisocyanate and a polyol. When the urethane raw material contains multiple components, some or all of the components may be mixed in the reaction system.

[0019] When polyisocyanate and polyol are added as urethane raw materials, for example, 10 to 200 parts by mass of polyol can be added relative to 100 parts by mass of polyisocyanate, and preferably 50 to 150 parts by mass of polyol can be added. Specific examples of the amount of polyol added relative to 100 parts by mass of polyisocyanate include 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, and 200 parts by mass, and may be within a range between any two of the values exemplified here.

[0020] <Polyisocyanate> Examples of polyisocyanates include aromatic isocyanates, alicyclic isocyanates, and aliphatic isocyanates.

[0021] Examples of aromatic isocyanates include phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, dimethyldiphenylmethane diisocyanate, triphenylmethane triisocyanate, naphthalene diisocyanate, and polymethylene polyphenyl polyisocyanate.

[0022] Examples of alicyclic isocyanates include cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and dimethyldicyclohexylmethane diisocyanate.

[0023] Examples of the aliphatic isocyanate include methylene diisocyanate, ethylene diisocyanate, propylene diisocyanate, tetramethylene diisocyanate, and hexamethylene diisocyanate.

[0024] One or more types of polyisocyanates can be used.

[0025] <Urethane prepolymer> The urethane prepolymer is a polymer obtained by reacting a polyol with an excess amount of polyisocyanate, and is a compound having an isocyanate group at the molecular end.

[0026] <Polyol> Examples of polyols include polylactone polyols, polycarbonate polyols, aromatic polyols, alicyclic polyols, aliphatic polyols, polyester polyols, polymer polyols, and polyether polyols.

[0027] Examples of polylactone polyols include polypropiolactone glycol, polycaprolactone glycol, and polyvalerolactone glycol.

[0028] Examples of polycarbonate polyols include polyols obtained by dealcoholization reaction of a hydroxyl group-containing compound such as ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, octanediol, or nonanediol with diethylene carbonate or dipropylene carbonate.

[0029] Examples of aromatic polyols include bisphenol A, bisphenol F, phenol novolac, and cresol novolac.

[0030] Examples of alicyclic polyols include cyclohexanediol, methylcyclohexanediol, isophoronediol, dicyclohexylmethanediol, and dimethyldicyclohexylmethanediol.

[0031] Examples of the aliphatic polyol include ethylene glycol, propylene glycol, butanediol, pentanediol, and hexanediol.

[0032] Examples of polyester polyols include polymers obtained by dehydration condensation of polybasic acids and polyhydric alcohols, polymers obtained by ring-opening polymerization of lactones such as ε-caprolactone and α-methyl-ε-caprolactone, and condensates of hydroxycarboxylic acids and the above-mentioned polyhydric alcohols.

[0033] Examples of polymer polyols include polymers obtained by graft polymerizing an ethylenically unsaturated compound such as acrylonitrile, styrene, methyl acrylate, or methacrylate onto an aromatic polyol, an alicyclic polyol, an aliphatic polyol, or a polyester polyol; polybutadiene polyol; modified polyols of polyhydric alcohols; and hydrogenated products thereof.

[0034] Examples of polyether polyols include polymers obtained by ring-opening polymerization of at least one alkylene oxide such as ethylene oxide, propylene oxide, or tetrahydrofuran in the presence of at least one low-molecular-weight active hydrogen compound having two or more active hydrogens.

[0035] One or more types of polyols can be used.

[0036] <Foaming agent> The foaming agent promotes foaming of the urethane. Examples of foaming agents include hydrofluoroolefins having 3 or 4 carbon atoms, such as trans-1-chloro-3,3,3-trifluoropropene, and water. Among these, water, in which sodium silicate is easily dissolved, is preferred.

[0037] <Thermal Expandable Graphite> Thermally expandable graphite is a crystalline compound that maintains the layered structure of graphite and is produced by treating powders of natural graphite, pyrolytic graphite, or the like with an inorganic acid such as sulfuric acid or nitric acid and a strong oxidizing agent such as concentrated nitric acid or permanganate. When exposed to temperatures of about 200°C or higher, it thermally expands, for example, by 100 times or more. These powders of natural graphite, pyrolytic graphite, and the like are available in various varieties, including those that have been deoxidized and further neutralized, and any of these can be used.

[0038] The content of the thermally expandable graphite is 5 to 100 parts by mass, preferably 20 to 85 parts by mass, and more preferably 35 to 70 parts by mass, per 100 parts by mass of the urethane compound. The content of the thermally expandable graphite is, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 parts by mass per 100 parts by mass of the urethane compound, and may be within a range between any two of the values exemplified here. If the content of the thermally expandable graphite is less than 20 parts by mass, the thermal expansion of the fire-resistant material in the event of a fire will be poor. On the other hand, if the content of the thermally expandable graphite is more than 100 parts by mass, the shape stability of the thermally expandable fire-resistant material after thermal expansion will be poor.

[0039] <Sodium silicate> Sodium silicate itself is a solid, but its aqueous solution is an alkaline viscous liquid also known as water glass, and there are five types, No. 1 to No. 5, depending on the ratio of the three components: silicon dioxide (SiO2), sodium oxide (Na2O), and water (H2O). Sodium silicate can function as a shape-retaining agent, and adding an appropriate amount of sodium silicate can improve shape stability after thermal expansion. Sodium silicate can be used alone or in combination of two or more types.

[0040] The content of sodium silicate is 0.5 to 30 parts by mass, preferably 5 to 25 parts by mass, and more preferably 10 to 20 parts by mass, relative to 100 parts by mass of the urethane compound. Specifically, the content of sodium silicate is, for example, 0.5, 1, 5, 10, 15, 20, 25, or 30 parts by mass, relative to 100 parts by mass of the urethane compound, and may be within a range between any two of the values exemplified here. If the content of sodium silicate is less than 0.5 parts by mass, shape stability after thermal expansion is poor. If the content of sodium silicate exceeds 30 parts by mass, the hardness increases, resulting in poor thermal expansion properties.

[0041] The thermally expandable urethane foam composition may also contain other additives as needed, provided that the properties are not impaired, such as inorganic compounds, surfactants, foam stabilizers, catalysts, blowing agents, flame retardants, stabilizers, UV absorbers, antioxidants, pigments, etc.

[0042] Alternatively, an inorganic sheet using fibers such as silica or alumina may be laminated.

[0043] A test piece obtained by molding the heat-expandable fire-resistant urethane foam composition into a rectangular parallelepiped having dimensions of 30 mm wide x 30 mm long x 10 mm high has its first surface (top surface) and second surface (bottom surface) of 30 mm wide x 30 mm long measured for Shore E hardness under a load of 1 kg in an environment of 21°C according to JIS K6253.The Shore E hardness of the first surface and the second surface is, for example, less than 25, preferably less than 20, and more preferably less than 15.

[0044] The hardness difference, which is the absolute value of the difference between the Shore E hardness of the first surface and the Shore E hardness of the second surface and is expressed by the following formula, is preferably less than 5, more preferably less than 3, and even more preferably less than 1. A thermally expandable fire-resistant urethane foam composition having such a small hardness difference can be obtained, for example, by a production method using the water-glass reaction described below. Hardness difference = |(Shore E hardness of the first surface) - (Shore E hardness of the second surface)|

[0045] The test piece for measuring the hardness related to the hardness difference can be prepared, for example, by the method described in the examples below.

[0046] (Manufacturing method: water-glass reaction) A method for producing a thermally expandable fire-resistant urethane foam composition according to one embodiment of the present invention includes a blending step of blending an isocyanate compound with a sodium silicate solution (preferably an aqueous sodium silicate solution) in which thermally expandable graphite has been dispersed. In this blending step, foam molding is performed by blending accompanied by addition, stirring, etc. The content of the blowing agent (e.g., water) contained in the sodium silicate solution is preferably 10 parts by mass or more, more preferably 50 to 500 parts by mass, and even more preferably 80 to 200 parts by mass per 100 parts by mass of the isocyanate compound.

[0047] In addition, the method for producing a heat-expandable fire-resistant urethane foam composition can further include a preparation step of blending a solvent (preferably water) with a mixture of heat-expandable graphite and sodium silicate to prepare a sodium silicate solution in which the heat-expandable graphite is dispersed.

[0048] The method for producing a heat-expandable fire-resistant urethane foam composition may further include a drying step of drying the urethane foam composition (foam) after foam molding. The drying step may be carried out at a temperature of, for example, 70 to 100°C (for example, 80°C).

[0049] (Manufacturing method: Water glass impregnation) According to another aspect of the present invention, a method for producing a heat-expandable fire-resistant urethane foam composition includes a blending step of blending an isocyanate compound with a mixed liquid in which heat-expandable graphite is dispersed (preferably a mixed liquid in which heat-expandable graphite is dispersed in water), and an impregnation step of impregnating a foam (urethane foam) obtained from the blending step with a sodium silicate solution (preferably an aqueous sodium silicate solution).

[0050] In the blending step, foam molding is carried out by blending accompanied by addition, stirring, etc. The content of the blowing agent (e.g., water) contained in the mixed liquid is preferably 10 parts by mass or more, more preferably 50 to 500 parts by mass, and even more preferably 80 to 200 parts by mass, relative to 100 parts by mass of the isocyanate compound.

[0051] The method for producing a heat-expandable fire-resistant urethane foam composition may further include a first drying step of drying the urethane foam composition (foam) after foam molding. The method for producing a heat-expandable fire-resistant urethane foam composition may further include a second drying step of drying the urethane foam composition (impregnated foam) after impregnation. These drying steps may be carried out at a temperature of, for example, 70 to 100°C (80°C in one example).

[0052] 2. Heat-expandable fire-resistant urethane foam joint material A heat-expandable fire-resistant urethane foam joint material according to one embodiment of the present invention is a fire-resistant joint material using the heat-expandable urethane foam composition. The heat-expandable fire-resistant urethane foam joint material can be composed of the heat-expandable urethane foam composition. The heat-expandable fire-resistant urethane foam joint material can be used in a variety of fields requiring properties such as elasticity, flexibility, thermal expansion, insulation, fire resistance, vibration damping, and soundproofing. It can also be applied to known construction methods using fire-resistant expandable materials, and can be used according to the instructions for each construction method. There are no particular limitations on the location of use, and it can be used widely in places where fire resistance is required.

[0053] The thermally expandable fire-resistant urethane foam joint sealant is used to partially or completely seal gaps in penetrations in fire compartments. It is also suitable for use in fire-resistant areas of seismic isolation devices in buildings. Specifically, the fire joint sealant of the present invention can be used to cover gaps between a fire compartment, such as a fire wall or floor slab, and a power cable, communication cable, or pipe passing through a penetration. It can also be used with a gasket molded to fit the installation area. The fire joint sealant can also be used between the seismic isolation device itself and the fire-resistant panel covering it, or at the edge of the fire-resistant panel. It can be attached with adhesive or glue, or secured with bolts or nails. [Example]

[0054] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following description, parts and percentages are based on mass.

[0055] <Preparation of urethane foam composition by sodium silicate aqueous solution reaction> (A: When polyisocyanate was used as the isocyanate compound [Examples 4 to 5] ) Water was added to a mixture of thermally expandable graphite and sodium silicate in the amounts shown in Tables 1 to 3 to prepare aqueous solutions of thermally expandable graphite-mixed sodium silicate. Polyisocyanate and polyol (100 parts by mass of urethane raw material in the table includes 50 parts by mass of polyisocyanate and 50 parts by mass of polyol) were added to this aqueous solution and stirred, then poured into a cylindrical mold 10 cm in diameter x 15 cm in height to foam-mold, and the mixture was left together with the mold in an oven at 80°C for 3 days to evaporate the water, yielding a sample raw material of a urethane foam composition. The amount of water was 100 parts by mass per 50 parts by mass of polyisocyanate. (B: When a urethane prepolymer was used as the isocyanate compound [Examples 6 to 24, Comparative Examples 1 to 4]) Water was added to a mixture of thermally expandable graphite and sodium silicate in the amounts shown in Tables 1 to 3 to prepare aqueous solutions of thermally expandable graphite-mixed sodium silicate. The urethane prepolymer was added to this aqueous solution and stirred, and the mixture was poured into a cylindrical mold 10 cm in diameter x 15 cm in height to form a foam. The mixture was then left together with the mold in an oven at 80°C for 3 days to evaporate the water, yielding a sample of the urethane foam composition. The amount of water was 200 parts by mass per 100 parts by mass of the urethane prepolymer. (Common to A and B: Cutting out sample pieces) Then, as shown in Figure 1, each sample body was cut in half horizontally at a position 75 mm from the top surface, and a sample piece measuring 30 mm wide x 30 mm long x 10 mm high was taken from the center of the circle on the cut surface.

[0056] <Preparation of urethane foam composition by impregnation with sodium silicate aqueous solution [Examples 1 to 3]> Water was added to thermally expandable graphite in the amounts shown in Tables 1 to 3 to prepare aqueous solutions containing thermally expandable graphite. A urethane prepolymer was added to this aqueous solution and stirred, and the mixture was poured into a cylindrical mold 10 cm in diameter and 15 cm in height to foam-mold it. The mixture was then left together with the mold in an oven at 80°C for 3 days to evaporate the water, yielding a sample raw material of the urethane foam composition. The sample was then cut in half horizontally at a position 75 mm from the top surface, and a sample measuring 30 mm wide x 30 mm long x 10 mm high was taken from the center of the circle on the half-cut surface. This was then immersed in a sodium silicate aqueous solution (solid content concentration 40 wt%, water glass No. 2) at 21°C for 24 hours, and after being removed, one side (30 mm wide x 30 mm long) was placed facing down and left to stand in an oven at 80°C for 3 days to evaporate the water and obtain a sample piece. The sodium silicate content (parts by mass) was calculated by measuring the weight before and after immersion in the sodium silicate aqueous solution. The amounts of urethane prepolymer and water used to prepare the heat-expandable fire-resistant urethane foam composition were the same (urethane prepolymer:water = 100 parts by mass: 100 parts by mass).

[0057] The materials used in the examples and comparative examples are shown below. The amount of sodium silicate in the examples and comparative examples is a value calculated as a solid content excluding water.

[0058] <Polyisocyanate> Toluene-2,4-diisocyanate: Cosmonate T100 manufactured by Mitsui Chemicals, Inc. Bis(4-isocyanatophenyl)methane: "Cosmonate PH" manufactured by Mitsui Chemicals, Inc. <Polyol> Polyether polyol: Sannix FA-195 manufactured by Sanyo Chemical Industries, Ltd. <Urethane prepolymer> Polyether: Mitsui Chemicals "Hypren EGH-401" Polyether: "Hyprene L-80" manufactured by Mitsui Chemicals, Inc. Polyester: "Takenate L-1270" manufactured by Mitsui Chemicals, Inc. <Thermal Expandable Graphite> Thermally expandable graphite: "SS-3" manufactured by Air Water Chemical Co., Ltd. <Sodium silicate aqueous solution (water glass)> No. 1: SiO2 33%, Na2O 16%, H2O 51%, manufactured by Fuji Chemical Co., Ltd. No. 2: SiO2 28%, Na2O 12%, H2O 60%, manufactured by Fuji Chemical Co., Ltd. No. 3: SiO2 29%, Na2O 10%, H2O 61%, manufactured by Fuji Chemical Co., Ltd. No. 4: SiO2 25%, Na2O 8%, H2O 67%, manufactured by Fuji Chemical Co., Ltd. No. 5: SiO2 26%, Na2O 7%, H2O 67%, manufactured by Fuji Chemical Co., Ltd. <Foaming agent> ·water

[0059] In the examples and comparative examples, the following properties were evaluated and are summarized in Tables 1 to 3. The measurement method for each property is shown below.

[0060] <Hardness> The sample pieces of the examples and comparative examples were prepared as test pieces measuring 30 mm in length, 30 mm in width, and 10 mm in thickness, and the Shore E hardness of the first surface (upper surface) and the second surface (lower surface), which were both surfaces of the 30 mm in length and 30 mm in width, was measured under a load of 1 kg in an environment of 21° C. in accordance with JIS K6253. Then, based on the measured values, the hardness was evaluated according to the following criteria. [Evaluation criteria] ⊚: Shore E hardness is less than 15. ◯: Shore E hardness is 15 or more and less than 20. △: Shore E hardness is 20 or more and less than 25. ×: Shore E hardness is 25 or more.

[0061] <Hardness uniformity> The hardness difference, which is the absolute value of the difference between the Shore E hardness of the first surface and the Shore E hardness of the second surface, was calculated using the following formula, and the hardness uniformity was evaluated using the following evaluation criteria. Hardness difference = |(Shore E hardness of the first surface) - (Shore E hardness of the second surface)| [Evaluation criteria] ⊚: The hardness difference is less than 3. ○: The hardness difference is 3 or more and less than 5. △: The hardness difference is 5 or more and less than 12. ×: The hardness difference is 12 or more.

[0062] <Thermal expansion> The sample pieces of the examples and comparative examples were cut into test pieces measuring 30 mm in length, 30 mm in width, and 10 mm in thickness, and the volumes of these were measured after leaving them in an atmosphere maintained at 600°C for 0.5 hours, and the expansion ratio was calculated from the volumes. Then, based on the volume expansion ratio, the thermal expandability was evaluated according to the following evaluation criteria. [Evaluation criteria] ◎: The volume expansion ratio is 6 times or more. ○: The volume expansion ratio is 4 times or more and less than 6 times. △: The volume expansion ratio is 2 times or more and less than 4 times. ×: The volume expansion ratio is less than 2 times.

[0063] <Shape stability after thermal expansion> The test pieces of the examples and comparative examples were cut into test pieces measuring 30 mm long x 30 mm wide x 10 mm thick. These were then left in an atmosphere maintained at 600°C for 0.5 hours, and then the strength (three-point bending fracture strength) of the test pieces was measured at a compression rate of 50 mm / min using a three-point bending test jig (upper pushing side tip R1 mm and width 80 mm, lower two-point support side R1 mm, width 80 mm, distance between supports 20 mm). Here, a higher three-point bending fracture strength indicates better shape stability after thermal expansion. Based on the three-point bending fracture strength, the shape stability after thermal expansion was evaluated according to the following criteria. [Evaluation criteria] ⊚: Three-point bending breaking strength is 3.0 [N] or more. ◯: The three-point bending breaking strength is 2.0 [N] or more and less than 3.0 [N]. △: The three-point bending breaking strength is 1.0 [N] or more and less than 2.0 [N]. ×: The three-point bending breaking strength is less than 1.0 [N].

[0064] [Table 1]

[0065] [Table 2]

[0066] [Table 3]

[0067] In urethane foam compositions impregnated with a sodium silicate aqueous solution (water glass) by sodium silicate aqueous solution impregnation, the impregnated sodium silicate accumulates at the bottom of the foam due to gravity, and the composition tends to have less uniform hardness and poorer thermal expansion properties than those produced by a sodium silicate aqueous solution reaction.

Claims

1. A thermally expandable fire-resistant urethane foam composition comprising 20 to 85 parts by mass of thermally expandable graphite and 10 to 20 parts by mass of sodium silicate per 100 parts by mass of a urethane compound, the urethane compound includes a urethane prepolymer or includes a structure derived from a urethane prepolymer, The heat-expandable fire-resistant urethane foam composition is molded into a rectangular parallelepiped having dimensions of 30 mm width x 30 mm length x 10 mm height. The first and second surfaces of the 30 mm width x 30 mm length test specimen are measured for Shore E hardness under a load of 1 kg in accordance with JIS K6253 at 21°C. The hardness difference, which is the absolute value of the difference between the Shore E hardness of the first surface and the Shore E hardness of the second surface, is expressed by the following formula: Hardness difference = |(Shore E hardness of first surface) - (Shore E hardness of second surface)| A thermally expandable fire-resistant urethane foam composition.

2. 2. A method for producing the thermally expandable fire-resistant urethane foam composition according to claim 1, comprising the step of blending an isocyanate compound with an aqueous sodium silicate solution in which thermally expandable graphite has been dispersed to produce a urethane compound.

3. A fire-resistant joint material using the fire-resistant urethane foam composition according to claim 1.

Images