Thermally-expandable composition and refractory material

Abstract

To provide a thermally-expandable composition that enables the production of a refractory material having fire resistance and high moldability.SOLUTION: A thermally-expandable composition contains one or more matrix components selected from the group consisting of elastomer components, and thermally-expandable graphite, the thermally-expandable composition having a gel fraction of 50-87%.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a thermally expandable composition and a fire-resistant material. [Background technology]

[0002] In the field of construction, fireproof materials are used in building materials such as fittings, pillars, and wall materials for fire prevention. Examples of fireproof materials include fireproof materials made of resin mixed with rubber and thermally expandable graphite (see, for example, Patent Document 1). Such fireproof materials expand when heated, and the combustion residue forms a fireproof insulation layer, thereby achieving fireproof insulation performance. A fire-resistant material containing thermally expandable graphite is placed, for example, in the gap between fittings such as doors and windows installed in openings in buildings and the frames surrounding them, such as door frames and window frames; in the event of a fire, the sheet expands in the thickness direction to close the gap between the fittings and the frames and prevent the fire from spreading. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-141463 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, fireproof materials containing rubber may become hard or brittle due to the tendency of the rubber to crystallize, etc. This tendency is particularly pronounced when used in cold regions, and the hardening can lead to problems such as poor workability or the occurrence of cracks on the surface, making the material difficult to handle. Considering the above problems, a method of adding a plasticizer with a low freezing point during the production of a fire-resistant material is conceivable in order to inhibit the crystallization tendency of rubber and improve the brittleness of the fire-resistant material. However, in that case, when used as a fire-resistant material, the sheet becomes soft and expands highly, but the residual hardness becomes brittle, and the fire resistance decreases. Therefore, an object of the present invention is to provide a thermally expandable composition capable of forming a refractory material having improved brittleness, excellent cold resistance, and excellent fire resistance due to high strength of residual hardness.

Means for Solving the Problems

[0005] As a result of intensive studies, the present inventors have found that in a thermally expandable composition composed of an elastomer component and thermally expandable graphite, the above problems can be solved by adjusting the gel fraction to 50 to 87%, and have completed the following present invention. That is, the present invention provides the following [1] to [6]. [1] A thermally expandable composition containing at least one matrix component selected from the group consisting of elastomer components and thermally expandable graphite, wherein the gel fraction of the thermally expandable composition is 50 to 87%. [2] The thermally expandable composition according to [1], containing 30% by mass or more of the thermally expandable graphite. [3] The thermally expandable composition according to [1] or [2], wherein the matrix component contains a component having at least one of a halogen atom, or a structural unit derived from styrene or acrylonitrile. [4] The thermally expandable composition according to any one of [1] to [3], wherein the expansion start temperature of the thermally expandable graphite is 150°C or higher. [5] The thermally expandable composition according to any one of [1] to [4], which does not contain a phosphorus component. [6] A refractory material comprising the thermally expandable composition according to [1] to [5].

Effects of the Invention

[0006] According to the present invention, it is possible to provide a thermally expandable composition capable of manufacturing a refractory material having excellent cold resistance and excellent fire resistance.

Modes for Carrying Out the Invention

[0007] Hereinafter, the present invention will be described using embodiments. [Thermally Expandable Composition] The thermally expandable composition of the present invention is a thermally expandable composition containing one or more matrix components selected from the group consisting of elastomer components and thermally expandable graphite.

[0008] <Gel fraction> The thermally expandable composition of the present invention has a gel fraction of 50 to 87%. When the gel fraction is less than 50%, the residual hardness of the refractory material becomes low, the fire resistance is impaired, or the cold resistance becomes low. On the other hand, when the gel fraction exceeds 87%, the thermally expandable composition becomes too hard, the expansion of the refractory material does not proceed sufficiently, or the residue becomes brittle, and the fire resistance is also impaired. From these viewpoints, the gel fraction is preferably 55 to 85%, more preferably 60 to 82%, and even more preferably 65 to 80%. In addition, the method for adjusting the gel fraction in the present invention is not particularly limited as long as it can be adjusted within the above range. Specifically, the use of a crosslinking agent, a crosslinking accelerator, irradiation with an electron beam, etc. can be mentioned. Among these, the use of a crosslinking agent and a crosslinking accelerator is preferable. The method for measuring the gel fraction is as described in the examples. As described later, the insoluble matter in an organic solvent (xylene) is used as the gel fraction to measure the gel fraction. Therefore, the gel fraction also includes insoluble matter in organic solvents such as inorganic fillers and thermally expandable graphite contained in the thermally expandable composition.

[0009] It is preferable that a crosslinking agent is blended in the thermally expandable composition. The crosslinking agent is not particularly limited as long as it can adjust the gel fraction of the thermally expandable composition within the above range. Specifically, sulfur-based crosslinking agents, metal oxide-based crosslinking agents, peroxide-based crosslinking agents, resin-based crosslinking agents, amine-based crosslinking agents, oxime-based crosslinking agents, etc. can be mentioned. When a crosslinking agent is used in the thermally expandable composition of the present invention, from the viewpoint of easily adjusting the gel fraction of the thermally expandable composition to a desired range, it is preferable to use a sulfur-based crosslinking agent, and it is more preferable to use a sulfur-based crosslinking agent in combination with a metal oxide-based crosslinking agent. As the sulfur-based crosslinking agent, inorganic ones such as sulfur, insoluble sulfur, precipitated sulfur, sulfur chloride, sulfur monochloride, sulfur dichloride, etc. may be used, or sulfur-containing organic crosslinking agents may also be used. Examples of the sulfur-containing organic crosslinking agents include morpholine disulfide, alkylphenol disulfide, N,N'-dithio-bis(hexahydro-2H-azepinone-2), thiuram polysulfide, 2-(4'-morpholino·dithio)benzothiazole, etc. Among these, from the viewpoint of crosslinkability, inorganic ones are preferred, and sulfur is more preferred.

[0010] Examples of the metal oxide-based crosslinking agents include zinc oxide, magnesium oxide, etc. When using a metal oxide in the present invention, it is preferable to use zinc oxide. The crosslinking agent may be used alone or in combination of two or more. From the viewpoint of easily adjusting the gel fraction of the thermally expandable composition to a desired range, it is preferable to use two in combination. As described above, it is more preferable to use a metal oxide-based crosslinking agent and a sulfur-based crosslinking agent in combination.

[0011] Also, a so-called masterbatch may be used as the crosslinking agent. As the masterbatch, a mixture of the above crosslinking agent and a resin can be used. It is preferable to use a sulfur masterbatch for inorganic sulfur-based crosslinking agents such as sulfur.

[0012] When using a crosslinking agent in the thermally expandable composition of the present invention, the blending amount of the crosslinking agent is not particularly limited, but is preferably 0.5 to 5% by mass, more preferably 1 to 3.5% by mass, and even more preferably 1.5 to 3% by mass. More specifically, for example, when using a sulfur-based crosslinking agent and a metal oxide crosslinking agent in combination, the blending amount of the sulfur-based crosslinking agent is preferably 0.2 to 3% by mass, more preferably 0.3 to 2% by mass, and even more preferably 0.6 to 1.5% by mass. Also, the blending amount of the metal oxide crosslinking agent is preferably 0.3 to 4% by mass, more preferably 0.5 to 3% by mass, and even more preferably 0.8 to 2.4% by mass. Note that the compounding amount of the crosslinking agent, when compounded together with components such as resins other than the crosslinking agent such as masterbatch, is the amount excluding the components other than the crosslinking agent.

[0013] It is also preferable that a crosslinking accelerator is compounded in addition to the crosslinking agent in the thermally expandable composition. The crosslinking accelerator used in the thermally expandable composition of the present invention is not particularly limited, and examples thereof include thiazole-based compounds, sulfenamide-based compounds, thiuram-based compounds, dithiocarbamate-based compounds, guanidine-based compounds, and the like. Among these, thiazole-based compounds are preferable, and zinc bis(benzothiazole-2-ylthio) is more preferable. The crosslinking accelerator may be used alone or in combination of two or more.

[0014] When a crosslinking accelerator is used in the thermally expandable composition of the present invention, the compounding amount of the crosslinking accelerator is not particularly limited, but is preferably 0.1 to 5% by mass, more preferably 0.2 to 3% by mass, and still more preferably 0.3 to 2% by mass.

[0015] <Matrix component> The thermally expandable composition of the present invention contains an elastomer component as a matrix component.

[0016] (Elastomer component) The elastomer component in the matrix component is not particularly limited, and examples thereof include diene rubbers such as isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), hydrogenated styrene-butadiene copolymer rubber (HSBR), chloroprene rubber (CR), acrylonitrile-butadiene rubber (NBR), hydrogenated acrylonitrile-butadiene rubber (HNBR), rubber components such as ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), natural rubber, butyl rubber, chlorinated butyl rubber, chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, multi-vulcanized rubber, non-vulcanized rubber, silicone rubber, fluororubber, urethane rubber, etc.

[0017] As the elastomer component, it is preferable to contain a component having at least one of a halogen atom, or a structural unit derived from styrene or acrylonitrile. These elastomer components tend to have good fire resistance, but have high crystallinity and tend to have low cold resistance. In the present invention, the cold resistance is also improved by setting the gel fraction within the above range. From such a viewpoint, as the elastomer component, at least one selected from styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), and chloroprene rubber (CR) is preferable, and at least one selected from styrene-butadiene rubber (SBR) and chloroprene rubber (CR) is more preferable.

[0018] The matrix component may be composed of a component having at least one of a halogen atom, or a structural unit derived from styrene or acrylonitrile as described above, or may contain other components other than the component. As other components, from the viewpoint of moldability, EPDM is preferable. In addition, from the viewpoint of fire resistance, the component having at least one of a halogen atom, or a structural unit derived from styrene or acrylonitrile is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, still more preferably 70 to 100% by mass, and even more preferably 85 to 100% by mass based on the total amount of the matrix component.

[0019] In addition, from the viewpoint of improving fire resistance and cold resistance by enhancing the dispersibility of thermally expandable graphite or inhibiting the crystallization tendency of the elastomer component, it is also preferable to use styrene-butadiene rubber (SBR) and chloroprene rubber (CR) in combination. When styrene-butadiene rubber (SBR) and chloroprene rubber (CR) are used in combination, the content ratio (SBR / CR) thereof is preferably 90 / 10 to 10 / 90 by mass ratio, and more preferably 80 / 20 to 20 / 80 by mass ratio.

[0020] The bound styrene content of the styrene-butadiene rubber (SBR) used in the present invention is not particularly limited, but from the viewpoint of improving the moldability of the refractory, it is, for example, 10 to 60% by mass, preferably 15 to 55% by mass, and more preferably 20 to 50% by mass. The bound styrene content can be measured by 1 1H-NMR. Further, the Mooney viscosity [ML(1+4) 100°C] of the styrene-butadiene rubber is not particularly limited, but from the viewpoint of improving the moldability of the refractory, it is, for example, 30 to 150, preferably 35 to 70, and more preferably 40 to 60.

[0021] The Mooney viscosity [ML(1+4) 100°C] of the chloroprene rubber (CR) is not particularly limited, but from the viewpoint of improving the moldability of the refractory, it is, for example, 25 to 150, preferably 30 to 100, and more preferably 35 to 75. In this specification, the Mooney viscosity is a value measured in accordance with JIS K6300.

[0022] The content of the matrix component in the thermally expandable composition is preferably 65% by mass or less, more preferably 60% by mass or less. Also, it is preferably 20% by mass or more, more preferably 25% by mass or more, and even more preferably 35% by mass or more. By setting the matrix component to be below the above upper limit value, a certain amount or more of a crosslinking agent, a crosslinking accelerator, thermally expandable graphite, and an inorganic filler can be contained in the thermally expandable composition. Also, by setting it to be below the above lower limit value, it is easy to improve the moldability and the like.

[0023] <Thermally Expandable Graphite> Thermally expandable graphite expands when heated. It is obtained by treating powders such as natural flake graphite, pyrolytic graphite, and kish graphite with an inorganic acid and a strong oxidizing agent to form a graphite intercalation compound, and is a kind of crystalline compound that maintains the layered structure of carbon. Examples of the inorganic acid include concentrated sulfuric acid, nitric acid, and selenic acid. Examples of the strong oxidizing agent include concentrated nitric acid, perchloric acid, perchlorate, permanganate, dichromate, and hydrogen peroxide. Further, the thermally expandable graphite obtained by the acid treatment as described above may be further neutralized with a neutralizing agent such as ammonia, aliphatic lower amines, alkali metal compounds, alkaline earth metal compounds, etc. Examples of the aliphatic lower amines include monomethylamine, dimethylamine, trimethylamine, ethylamine, propylamine, butylamine and the like. Examples of the alkali metal compounds and the above-mentioned alkaline earth metal compounds include hydroxides, oxides, carbonates, sulfates, organic acid salts, etc. of potassium, sodium, calcium, barium, magnesium and the like.

[0024] From the viewpoint of preventing expansion except during a fire, the expansion start temperature of the thermally expandable graphite used in the present invention is preferably 150 ° C or higher, more preferably 155 ° C or higher, and even more preferably 160 ° C or higher. Also, during a fire, from the viewpoint of increasing the volume increase rate of the thermally expandable graphite and effectively exhibiting the fire resistance, it is preferably 250 ° C or lower, more preferably 240 ° C or lower, and even more preferably 230 ° C or lower.

[0025] The content of the thermally expandable graphite in the thermally expandable composition is, for example, preferably 10% by mass or more, preferably 20% by mass or more, more preferably 30% by mass or more, still more preferably 35% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. By setting the content of the thermally expandable graphite to the above content, it becomes easy to obtain expansion suitable for blocking the passage of fire, and the residue hardness also easily becomes an appropriate size, and an excellent refractory can be obtained.

[0026] <Inorganic filler> The thermally expandable composition of the present invention may contain an inorganic filler. The inorganic filler is an inorganic filler other than the above-mentioned thermally expandable graphite and crosslinking agent. When the inorganic filler is heated to form an expanded heat insulating layer, it increases the heat capacity, suppresses heat transfer, inhibits the crystallization tendency of the rubber component in the matrix component, and improves the cold resistance of the refractory.

[0027] From the perspective of improving the cold resistance of refractories, as the inorganic filler, it is preferable to include inorganic filler A with a specific gravity of 2.5 or more. By containing the inorganic filler A, the amount of the matrix component per unit volume can be increased, whereby the brittleness of the refractory is improved and the cold resistance is likely to be enhanced. From such a perspective, the specific gravity of the inorganic filler A is preferably 3 or more, more preferably 4 or more. For example, metal carbonates and the like can be used as the inorganic filler A with a specific gravity of 2.5 or more. The inorganic filler A may be used alone or in combination of a plurality of them. Based on the total amount of the inorganic filler, the content of the inorganic filler A is preferably 50% by mass or more, more preferably 80% by mass or more, and still more preferably 100% by mass.

[0028] As the inorganic filler, it is preferable to use the inorganic filler A with a specific gravity of 2.5 or more as described above, but it is also possible to use an inorganic filler with a specific gravity of less than 2.5. The inorganic filler that can be used in the present invention is not particularly limited. For example, metal oxides such as alumina, manganese oxide, titanium oxide, calcium oxide, iron oxide, tin oxide, antimony oxide, ferrite, and copper oxide; metal carbonates such as calcium carbonate, zinc carbonate, strontium carbonate, and barium carbonate; metal hydroxides such as calcium hydroxide, magnesium hydroxide, aluminum hydroxide, and hydrotalcite; calcium salts such as calcium sulfate, gypsum fiber, and calcium silicate; silica, diatomaceous earth, dacite, barium sulfate, talc, clay, mica, montmorillonite, bentonite, activated clay, sepiolite, imogolite, sericite, glass fiber, glass beads, silica-based balloons, aluminum nitride, boron nitride, silicon nitride, carbon black, graphite, carbon fiber, carbon balloons, various metal powders, potassium titanate, magnesium sulfate, lead zirconate titanate, aluminum borate, molybdenum sulfide, silicon carbide, stainless steel fiber, zinc borate, various magnetic powders, slag fiber, fly ash, metal phosphates such as sodium phosphate, potassium phosphate, magnesium phosphate, and aluminum phosphate; metal phosphites such as sodium phosphite, potassium phosphite, magnesium phosphite, and aluminum phosphite; ammonium polyphosphate, orthophosphate metal salts, metaphosphate metal salts, tripolyphosphate metal salts, etc. The inorganic filler may be used alone or in combination of two or more.

[0029] Among these, from the viewpoint of fire resistance, iron oxide, metal hydroxides, metal carbonates, etc. are also preferable as the inorganic filler. Furthermore, it is more preferable that the inorganic filler contains at least iron oxide. By containing iron oxide, it becomes easier to improve the fire resistance by increasing the expansion ratio and the residue hardness after expansion. Also, when containing iron oxide, the content of iron oxide is preferably 3 to 30% by mass, more preferably 5 to 15% by mass, and even more preferably 6 to 9% by mass with respect to the total amount of the fire-resistant resin composition.

[0030] Moreover, it is particularly preferable to use iron oxide and calcium carbonate in combination as the inorganic filler. When using iron oxide and calcium carbonate in combination, the mass ratio (iron oxide / calcium carbonate) is preferably 10 / 90 to 90 / 10, more preferably 20 / 80 to 80 / 20, and even more preferably 30 / 70 to 70 / 30.

[0031] The content of the inorganic filler in the thermally expandable composition is preferably 3% by mass or more, more preferably 8% by mass or more, even more preferably 10% by mass or more, and preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less.

[0032] <Other components> In addition to the crosslinking agent, crosslinking accelerator, matrix component, thermally expandable graphite, and inorganic filler described above, the thermally expandable composition may also contain various organic flame retardants such as bromine-containing flame retardants, nitrogen-containing flame retardants, and phosphate ester compounds, colorants, antioxidants, and other various additives.

[0033] Examples of bromine-containing flame retardants include hexabromobenzene, pentabromotoluene, hexabromobiphenyl, decabromobiphenyl, hexabromocyclodecane, decabromodiphenyl ether, octabromodiphenyl ether, hexabromodiphenyl ether, bis(pentabromophenoxy)ethane, ethylene-bis(tetrabromophthalimide), tetrabromobisphenol A, and the like.

[0034] Examples of nitrogen-containing flame retardants include melamine derivatives such as melamine, butyl melamine, trimethylol melamine, hexamethylol melamine, hexamethoxymethyl melamine, and melamine phosphate; cyanuric acid derivatives such as cyanuric acid, methyl cyanurate, diethyl cyanurate, trimethyl cyanurate, and triethyl cyanurate; isocyanuric acid derivatives such as isocyanuric acid, methyl isocyanurate, N,N'-diethyl isocyanurate, tris(methyl isocyanurate), tris(ethyl isocyanurate), bis(2-carboxyethyl) isocyanurate, 1,3,5-tris(2-carboxyethyl) isocyanurate, and tris(2,3-epoxypropyl) isocyanurate; and melamine cyanurate, melamine isocyanurate, and ethylenediamine phosphate.

[0035] Examples of phosphate ester compounds include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, octyldiphenyl phosphate, tributoxyethyl phosphate, trichloroethyl phosphate, tris(2-chloropropyl) phosphate, tris(2,3-dichloropropyl) phosphate, tris(2,3-dibromopropyl) phosphate, tris(bromochloropropyl) phosphate, bis(2,3-dibromopropyl)-2,3-dichloropropyl phosphate, bis(chloropropyl) monooctyl phosphate, tris(2-ethylhexyl) phosphate, triphenyl phosphate, tricresyl phosphate (TCP), trixylenyl phosphate, cresyldiphenyl phosphate, and xylenyl diphenyl phosphate. The organic flame retardant may be used alone or in combination of two or more. When using an organic flame retardant, the content of the organic flame retardant in the thermally expandable composition is, for example, 1 to 35% by mass, preferably 5 to 30% by mass, and more preferably 10 to 25% by mass.

[0036] The thermally expandable composition of the present invention preferably does not substantially contain organic flame retardants or other organic additives such as plasticizers. In this specification, organic salts composed of organic substances and inorganic substances such as ethylenediamine phosphate are also regarded as organic additives. In addition, among the above-mentioned crosslinking agents and crosslinking accelerators, those that are organic substances are organic additives, but the elastomer component and the resin component are not organic additives. Since the thermally expandable composition does not substantially contain organic additives, bleeding out due to plasticizers can be prevented, and contamination of peripheral members in contact with the thermally expandable composition such as sashes can be prevented. Here, "substantially does not contain" means that the content of the organic additive in the thermally expandable composition is less than 3% by mass, preferably less than 1% by mass.

[0037] <Phosphorus component> The thermally expandable composition of the present invention preferably does not contain a phosphorus component. By not containing a phosphorus component, the water resistance of the refractory formed from the thermally expandable composition is improved. Therefore, excellent expansion ratio, residue hardness, and shape retention after expansion can be ensured even after long-term exposure to water. Here, the phosphorus component is a compound containing a phosphorus atom. As the above-mentioned crosslinking agent, crosslinking accelerator, matrix component, thermally expandable graphite, inorganic filler, and organic flame retardant, colorant, antioxidant, etc. that are blended as needed, it is preferable not to use a compound containing a phosphorus atom.

[0038] From the viewpoint of fire resistance, the expansion ratio of the thermally expandable composition of the present invention is preferably 20.5 to 70 times, more preferably 25 to 60 times, and still more preferably 30 to 55 times. The thermally expandable composition of the present invention preferably exhibits an expansion ratio within the above range even after being immersed in water at 60°C for one week. If the expansion ratio is within the above range after long-term immersion in water, the water resistance is also good. The expansion ratio can be determined by measuring the change in the thickness direction before and after heating in a sheet-shaped thermally expandable composition.

[0039] In addition, the thermal expansion composition of the present invention preferably has a residual hardness after thermal expansion of 0.15 kgf / cm 2 or more, more preferably 0.20 kgf / cm 2 or more, still more preferably 0.27 kgf / cm 2 or more, even more preferably 0.30 kgf / cm 2 or more. From the viewpoint of ensuring fire resistance while maintaining a certain expansion ratio, the above residual hardness is preferably 0.70 kgf / cm 2 or less, more preferably 0.60 kgf / cm 2 or less, still more preferably 0.55 kgf / cm 2 or less. The thermal expansion composition of the present invention preferably exhibits a residual hardness within the above range even after being immersed in water at 60°C for one week. When the expanded residue is within the above range after long-term immersion in water, the water resistance is also good. The residual hardness can be determined by measuring the hardness of the expanded residue after heating and expanding the thermal expansion composition.

[0040] The shape of the thermal expansion composition is not particularly limited, but it is preferably formed into a predetermined shape such as a sheet shape. The thickness of the thermal expansion composition (also referred to as "refractory") formed into a predetermined shape is not particularly limited, but from the viewpoints of fire resistance and handleability, 0.2 to 10 mm is preferable, and 0.5 to 3.0 mm is more preferable.

[0041] The refractory of the present invention is excellent in cold resistance as described above, and it is difficult to cause problems such as cracking or surface cracking during use. Therefore, even when the length of the sheet is long, it has excellent handleability and can be used, for example, as a long product with a length of 1 m or more.

[0042] The thermal expansion composition of the present invention can be produced, for example, as follows. First, a predetermined amount of matrix component, thermally expandable graphite, and inorganic filler resin, as well as additives such as an organic flame retardant, colorant, antioxidant, etc. that are blended as necessary, are kneaded with a kneader such as a kneading roll to obtain a raw material mixture. Next, the obtained raw material mixture is crosslinked to obtain the thermally expandable composition of the present invention. The crosslinking of the raw material mixture is preferably carried out by heating. Specifically, for example, the raw material mixture is heated at 155 to 195 °C, preferably 160 to 180 °C, for example, for 5 to 30 minutes, preferably 10 to 25 minutes to crosslink. By heating for a predetermined time within such a temperature range, a predetermined gel fraction can be achieved. Also, the raw material mixture is preferably crosslinked while being formed into a desired shape. Specifically, it is preferably crosslinked while being formed into a desired shape such as a sheet by a known forming method such as press forming, calender forming, extrusion forming, etc. Further, it may be heated and crosslinked under the above heating conditions after being formed into a desired shape.

[0043] The thermally expandable composition of the present invention is used as a refractory material in various fields. The refractory material can be used in various buildings such as single-family houses, apartment houses, high-rise houses, high-rise buildings, commercial facilities, and public facilities, various vehicles such as automobiles and trains, and various vehicles such as ships and airplanes. When a fire breaks out in a building, vehicle, etc., the refractory material expands by being heated, blocks the flow of air, and can exhibit fire extinguishing properties. The refractory material is used by being attached to members constituting the above buildings, vehicles, ships, airplanes, etc. For example, in a building, it can be attached to fittings such as windows, shoji, doors, doors, fusuma, columns, walls such as reinforced concrete, floors, roofs, etc. to reduce or prevent the intrusion of fire and smoke. The refractory material can also be used as part of a partition penetration treatment material that closes the penetration part of a partition penetration structure. Among these, it is preferably used for fittings.

[0044] The refractory material may be used alone, or other members may be appropriately attached and used. For example, other members than the refractory material may be laminated, and a base material may be provided on at least one surface of the refractory material. The base material may be a combustible material layer, a semi-incombustible material layer, or an incombustible material layer. The thickness of the base material is not particularly limited, but is, for example, 5 μm to 1 mm. Examples of the material used for the combustible material layer include one or more of a cloth material, a paper material, wood, a resin film, etc. When the base material is a semi-incombustible material layer or an incombustible material layer, examples of the material used include metals, inorganic materials, etc. More specifically, woven or non-woven fabrics made of glass fiber, ceramic fiber, carbon fiber, graphite fiber, etc. may be mentioned. Also, a composite material of these fibers and metals may be used, and for example, aluminized glass cloth is preferable. In addition, an adhesive layer may be laminated on the refractory material. By using the adhesive layer, it becomes possible to easily adhere the refractory material to other members. The adhesive layer may be provided on the above-mentioned base material, or may be directly formed on the surface of the refractory material. Also, a double-sided adhesive tape having adhesive layers on both sides of the base material may be used. In this case, one adhesive layer may be attached to the refractory material, and the other adhesive layer may be used to bond to other members.

Examples

[0045] The present invention will be described more specifically with reference to the following examples, but the present invention is not limited thereto.

[0046] [Evaluation and measurement methods] (1) Expansion ratio Test pieces (length: 100 mm, width: 100 mm, thickness: 1.5 mm) made from the thermally expandable compositions obtained in each example and comparative example were immersed in 500 mL of pure water in a sealed container at 60 °C for 1 week, and then the samples were taken out. The test pieces prepared by evaporating and drying the samples at 60 °C for 96 hours were placed on the bottom surface of a stainless steel holder (101 mm square, height: 80 mm), supplied to an electric furnace, and heated at 600 °C for 30 minutes. Then, the lateral width, longitudinal width, and thickness of the portion with the largest thickness of the test piece were measured, and the expansion ratio was calculated by ((thickness of the test piece after heating) / (thickness of the test piece before heating)). (2) Residual hardness The test pieces after heating for which the expansion ratio had been measured were supplied to a compression testing machine (manufactured by Kato Tech Co., Ltd., "Finger Filling Tester"), compressed at a speed of 0.1 cm / second with a 3-point indenter having a diameter of 1 mm, the maximum stress up to 10 mm compression from the upper surface of the residue was measured, and the compression strength (kgf / cm 2 ) of the test piece after combustion was measured.

[0047] (3) Gel fraction The gel fraction was measured and calculated by the method described in the following (a) to (e). (a) Approximately 50 g of the thermally expandable composition was weighed, and the mass obtained by this weighing was designated as W1. (b) A bottomed cylindrical container made of SUS304 #100 mesh was weighed, and the mass obtained by this weighing was designated as W2. (c) The weighed thermally expandable composition was placed in the cylindrical container, and the composition together with the cylindrical container was immersed in 100 mL of toluene, left at room temperature (23 °C) for 7 days, and the sol fraction of the rubber component was filtered off. (d) The residue of the thermally expandable composition immersed and filtered by the method of (c) above was lifted out of the toluene together with the cylindrical container and filtered, and then the residue in the cylindrical container was dried at room temperature for 7 days and further dried at 80 °C for 24 hours, and the residue together with the cylindrical container was weighed, and the mass obtained by this weighing was designated as W3. (e) Based on W1 to W3 obtained in (a) to (d) above, the gel fraction was calculated using the following formula. Gel fraction (%) = ((W3 - W2) / W1) × 100

[0048] (4) Cold resistance (brittleness) The above test pieces obtained in each example and comparative example were fixed and sandwiched between parallel plates at 60 mm intervals and left at 0 °C for 5 minutes. After leaving, the interval between the parallel plates was quickly narrowed to 25 mm to bend the test piece, and the presence or absence of changes in the test piece due to the bending was visually confirmed. The evaluation criteria for changes in the test piece are as follows. 〇: No change △: Cracks occur on the surface ×: Fracture

[0049] (5) Expansion start temperature In a rheometer (“Discovery HR-2”, manufactured by TA Instruments), 0.5 g of a sample of thermally expandable graphite was placed on the sample stage and wrapped with aluminum foil so that the powder did not fall off. It was grounded with a 25 mmφ cone plate until the load reached 0 [N]. From that state, the sample was heated by a Peltier heater at a constant heating rate (10 °C / min) from a set temperature of 50 °C, and the time when the load reached 0.1 N was taken as the expansion start temperature.

[0050] (Examples 1 to 22, Comparative Examples 1 to 2) With the formulations shown in Tables 1 to 3 below, the matrix component, thermally expandable graphite, and inorganic filler were put into a kneader mixer and kneaded at 110 °C for 5 minutes to obtain a mixed composition. The obtained mixed composition was press-molded with a hot press machine to form a sheet while crosslinking the mixed composition to obtain a refractory material (thermally expandable composition) with a thickness of 1.5 mm. Each component used in each example and comparative example is as follows.

[0051] (1) Matrix component <Chloroprene rubber: CR> · CR “B-30” manufactured by Tosoh Corporation Mooney viscosity [ML(1+4)100 °C]: 45 to 53

[0052] <Styrene-butadiene rubber: SBR> · SBR “JSR1500” manufactured by JSR Corporation Bound styrene content: 23.5 mass%, Mooney viscosity [ML(1+4)100 °C]: 52 · SBR2 "JSR0202" manufactured by JSR Corporation Styrene content: 46% by mass, Mooney viscosity [ML(1+4)100℃]: 45 · SBR3 "JSR0122" manufactured by JSR Corporation Styrene content: 37% by mass, Mooney viscosity [ML(1+4)100℃]: 52

[0053] <Acrylonitrile-butadiene rubber: NBR> · NBR "N220S" manufactured by JSR Corporation

[0054] (2) Inorganic filler · Iron oxide: "BL-100" by Titanium Industry Co., Ltd., specific gravity 5.1 · Calcium carbonate: "WHITON BF-300" by Bihoku Powder Chemical Industry Co., Ltd., specific gravity 2.93

[0055] (3) Expansible graphite · Expansible graphite 1 "CA-60N" manufactured by Air Water Co., Ltd., expansion start temperature 220℃ · Expansible graphite 2 "EXP-50S150" manufactured by Fuji Graphite Industry Co., Ltd., expansion start temperature 160℃ (4) Crosslinking agent · Sulfur-based crosslinking agent "SUNMIX S-80N" manufactured by Sanshin Chemical Industry Co., Ltd., sulfur content 80% by mass, sulfur masterbatch · Zinc oxide "Zinc Oxide Type 2" manufactured by Sakai Chemical Industry Co., Ltd. (5) Crosslinking accelerator · Zinc bis(benzothiazole-2-ylthio) "SUNCELER MZ" manufactured by Sanshin Chemical Industry Co., Ltd.

[0056]

Table 1

Table 2

Table 3

[0057] As shown in the examples, the refractory formed from the thermally expandable composition containing thermally expandable graphite and having a gel fraction in the range of 50 to 87% has good fire resistance because of the high values of the expansion ratio and the residue hardness, and it was found that it is also excellent in cold resistance. On the other hand, as shown in the comparative examples, even if the refractory contains thermally expandable graphite, the refractory formed from the thermally expandable composition having a gel fraction outside the range of 50 to 87% had either impaired fire resistance or cold resistance.

Claims

1. A thermally expandable composition comprising one or more matrix components selected from the group consisting of elastomer components and thermally expandable graphite, The thermally expandable composition has a gel fraction of 50 to 87%.

2. The thermally expandable composition according to claim 1 , comprising 30 mass % or more of the thermally expandable graphite.

3. 3. The thermally expandable composition according to claim 1, wherein the matrix component contains a component having at least one of a halogen atom and a structural unit derived from styrene or acrylonitrile.

4. The thermally expandable composition according to any one of claims 1 to 3, wherein the thermally expandable graphite has an expansion initiation temperature of 150°C or higher.

5. The thermally expandable composition according to any one of claims 1 to 4, which does not contain a phosphorus component.

6. A fire-resistant material comprising the thermally expandable composition according to any one of claims 1 to 5.

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