Fire-resistant resin composition and heat-expandable sheet

Abstract

To provide a fire-resistant resin composition having excellent long-term fire resistance, and a thermally expandable sheet composed of the fire-resistant resin composition.SOLUTION: A fire-resistant resin composition has a resin, a thermally expandable graphite, and a flame retardant, wherein a difference between a decomposition temperature of the flame retardant and an expansion initiation temperature of the thermally expandable graphite (flame retardant decomposition temperature: thermally expandable graphite expansion initiation temperature) of 100°C or higher.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a fire-resistant resin composition and a thermally expandable sheet made of the fire-resistant resin composition.

Background Art

[0002] In the construction field, for fire protection, fire-resistant materials are used in building materials such as fittings, columns, and wall materials. As fire-resistant materials, fire-resistant sheets in which thermally expandable graphite is blended in addition to flame retardants, inorganic fillers, etc. in resins are used (for example, see Patent Document 1). Such fire-resistant materials expand by heating to form a fire-resistant heat-insulating layer with combustion residues and exhibit fire-resistant heat-insulating performance. The performance required for fire-resistant materials varies depending on the application. Generally, fire protection equipment such as sashes and doors is required to have a fire resistance of about 20 minutes, and when used for columns, beams, walls, etc., a long-term fire resistance of about 45 to 180 minutes is required.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Although conventional fire-resistant materials containing thermally expandable graphite have good fire-resistant performance in a relatively short time, when exposed to flames for a long time, the thermally expandable graphite gradually turns into ash, resulting in a decrease in strength and thus a decrease in fire resistance. Therefore, an object of the present invention is to provide a fire-resistant resin composition excellent in long-term fire resistance and a thermally expandable sheet made of the fire-resistant resin composition.

Means for Solving the Problems

[0005] As a result of diligent research to solve the above problems, the inventors have found that the above problems can be solved by adjusting the difference between the decomposition temperature of the flame retardant contained in a fire-resistant resin composition comprising a resin, thermally expandable graphite, and a flame retardant to a certain level or higher, thereby completing the present invention. That is, the present invention is as follows. [1] A fire-resistant resin composition comprising a resin, thermally expandable graphite, and a flame retardant, characterized in that the difference between the decomposition temperature of the flame retardant and the expansion onset temperature of the thermally expandable graphite (decomposition temperature of the flame retardant - expansion onset temperature of the thermally expandable graphite) is 100°C or higher. [2] The fire-resistant resin composition according to [1] above, wherein the content of the flame retardant is 0.05 to 1 by mass relative to the content of the thermally expandable graphite. [3] The fire-resistant resin composition according to [1] or [2] above, wherein the flame retardant is one or more selected from the group consisting of phosphorus-based flame retardants and bromine-based flame retardants. [4] A fire-resistant resin composition according to any one of [1] to [3] above, further comprising an organophosphorus compound other than the flame retardant. [5] The fire-resistant resin composition according to [4] above, wherein the organophosphorus compound is a phosphate ester compound. [6] A fire-resistant resin composition according to any one of [1] to [5] above, further comprising an inorganic filler. [7] The fire-resistant resin composition according to [6] above, comprising 10 to 200 parts by mass of an inorganic filler per 100 parts by mass of the resin. [8] A fire-resistant resin composition according to any one of [1] to [7] above, comprising 50 to 200 parts by mass of the thermally expandable graphite per 100 parts by mass of the resin. [9] The fire-resistant resin composition according to any one of [1] to [8] above, wherein the resin is polyvinyl chloride resin.

[10] A heat-expandable sheet made of the fire-resistant resin composition described in any of [1] to [9] above. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a fire-resistant resin composition that exhibits excellent long-term fire resistance, and a heat-expandable sheet made from the fire-resistant resin composition. [Modes for carrying out the invention]

[0007] [Fire-resistant resin composition] The fire-resistant resin composition of the present invention contains a resin, thermally expandable graphite, and a flame retardant, wherein the difference between the decomposition temperature of the flame retardant and the expansion onset temperature of the thermally expandable graphite (decomposition temperature of the flame retardant - expansion onset temperature of the thermally expandable graphite) is 100°C or higher. In this specification, the difference between the decomposition temperature of the flame retardant and the expansion onset temperature of the thermally expandable graphite is the value obtained by subtracting the expansion onset temperature of the thermally expandable graphite from the decomposition temperature of the flame retardant. The reason why the fire-resistant resin composition of the present invention exhibits excellent long-term fire resistance is not entirely clear, but it is presumed to be as follows: The thermally expandable graphite contained in the fire-resistant resin composition expands when the temperature exceeds the expansion initiation temperature, forming an expanded insulating layer. If the flame retardant decomposes before the thermally expandable graphite has expanded sufficiently, the uniformity of the flame retardant properties on the surface of the expanded insulating layer cannot be maintained, the shape retention of the expanded insulating layer decreases over time, and the fire resistance deteriorates. On the other hand, if the decomposition temperature of the flame retardant is sufficiently higher than the expansion initiation temperature of the thermally expandable graphite, the flame retardant decomposes after the thermally expandable graphite has expanded sufficiently, so a uniform flame retardant layer is formed around the surface of the expanded insulating layer. As a result, the shape of the expanded insulating layer is more easily maintained over a long period of time, and the fire resistance is considered to be improved.

[0008] The fire-resistant resin composition of the present invention has a difference of 100°C or more between the decomposition temperature of the flame retardant and the expansion onset temperature of the thermally expandable graphite. If the difference between the decomposition temperature of the flame retardant and the expansion onset temperature of the thermally expandable graphite is less than 100°C, the fire resistance of the fire-resistant resin composition will decrease. From the viewpoint of improving the fire resistance of the fire-resistant resin composition, it is preferable that the difference between the decomposition temperature of the flame retardant and the expansion onset temperature of the thermally expandable graphite be 120°C or more, more preferably 140°C or more, and even more preferably 200°C or more. Furthermore, from the viewpoint of the flame retardant decomposing appropriately during combustion and exhibiting a flame-retardant effect, it is preferable that the difference between the decomposition temperature of the flame retardant and the expansion temperature of the thermally expandable graphite be 500°C or less, and more preferably 400°C or less.

[0009] The decomposition temperature of the flame retardant is determined by measuring the temperature at which the mass of the flame retardant decreases by 10% using differential thermal-thermogravimetric analysis (TG-DTA), and this temperature is defined as the decomposition temperature. Furthermore, the expansion initiation temperature of thermally expandable graphite can be measured by raising the temperature of the thermally expandable graphite to a constant temperature using a device with a temperature control function and a normal force measuring device, and measuring the temperature at which the normal force begins to rise. The measuring device is not limited to those that can control the measurement temperature and measure normal stress, but for example, a rheometer can be used.

[0010] (Flame retardant) The flame retardant contained in the fire-resistant resin composition of the present invention can be appropriately selected from those in which the difference between the decomposition temperature of the flame retardant and the expansion onset temperature of the thermally expandable graphite is 100°C or more. That is, it can be appropriately selected considering the expansion onset temperature of the thermally expandable graphite used. The flame retardant can preferably be selected from those with a decomposition temperature of 250 to 600°C, more preferably 320 to 550°C, and even more preferably 350 to 500°C. If the decomposition temperature of the flame retardant is above these lower limits, it becomes easier to maintain a certain level of difference between this temperature and the expansion start temperature of the thermally expandable graphite. If the decomposition temperature is below these upper limits, the decomposition of the flame retardant makes it easier to improve fire resistance.

[0011] The type of flame retardant is not particularly limited as long as the difference between the decomposition temperature of the flame retardant and the expansion start temperature of the thermally expandable graphite is 100°C or more. It can be appropriately selected from phosphorus-based flame retardants, nitrogen-containing flame retardants, bromine-based flame retardants, chlorine-based flame retardants, halogen-based flame retardants, etc. From the viewpoint of further improving fire resistance, it is preferable to use one or more flame retardants selected from the group consisting of phosphorus-based flame retardants and bromine-based flame retardants.

[0012] As for phosphorus-based flame retardants, there are no particular limitations as long as the difference in expansion temperature with respect to the thermally expandable graphite used is 100°C or more. Examples include ammonium polyphosphate, melamine polyphosphate, melamine polymetaphosphate, melamine-melam-melem polyphosphate, phosphorus-based spiro compounds, and phosphazene compounds. Among these, phosphazene compounds and phosphorus-based spiro compounds are more preferred from the viewpoint of having a high decomposition temperature and being able to easily adjust the difference in expansion temperature with respect to the thermally expandable graphite to a certain level or higher. For the phosphorus-based flame retardant, either an organophosphorus flame retardant or an inorganic phosphorus flame retardant can be used, but it is preferable to use an organophosphorus flame retardant. Phosphazene compounds are organic compounds that have a -P=N- bond in their molecule. Among phosphazene compounds, those represented by the following general formula (1) are preferred due to their relatively high decomposition temperature. [ka] In formula (1) above, R1 to R6 each independently represent one of the following: an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an aryloxy group having 6 to 12 carbon atoms, an amino group, or a halogen atom. Examples of such phosphazene compounds include "SPB-100," which is commercially available from Otsuka Chemical Co., Ltd.

[0013] The phosphorus-based spiro compound is not particularly limited as long as it is a spiro compound having a phosphorus atom. Here, the spiro compound is a compound having a structure in which two cyclic compounds share one carbon, and the phosphorus-based spiro compound is a compound in which at least one of the elements constituting the two cyclic compounds is a phosphorus atom. As the phosphorus-based spiro compound, for example, it is preferable to use a compound having a structural unit represented by the following formula (2) in the molecule.

Chemical formula

[0014] The bromine-based flame retardant is not particularly limited as long as the difference between the decomposition temperature of the flame retardant and the expansion temperature of the expandable graphite used is 100 °C or more, and it may be an aliphatic bromine-based flame retardant or an aromatic bromine-based flame retardant. Examples of the aliphatic bromine-based flame retardant include tetrabromocyclooctane, hexabromocyclododecane, tris(dibromopropyl) phosphate, etc. Examples of the aromatic bromine-based flame retardant include decabromodiphenyl oxide, octabromodiphenyl oxide, brominated bisphenol A-based flame retardant, brominated bisphenol S-based flame retardant, etc. Among these, from the viewpoint of having a high decomposition temperature and being easy to adjust the difference from the expansion temperature of expandable graphite to a certain level or more, aromatic flame retardants are preferable, and among them, brominated bisphenol A-based flame retardants are more preferable. The brominated bisphenol A-based flame retardant may be a compound having a structural unit derived from bisphenol A in which at least one hydrogen atom is substituted with a bromine atom. The brominated bisphenol A-based flame retardant may have one such structural unit, but is preferably a brominated polycarbonate having a plurality of structural units. From the viewpoint of having a relatively high decomposition temperature, it is preferable to use a compound having a structural unit represented by the following formula (3) as the brominated bisphenol A-based flame retardant.

[0015]

Chemical formula

[0016] Among the compounds having the constituent units represented by formula (3) above, it is particularly preferable to use the compounds represented by the following formulas (4) and (5) below, from the viewpoint of having a high decomposition temperature and being able to easily adjust the difference with the expansion temperature of thermally expandable graphite to a certain level or higher. [ka] [ka] In the above formulas (4) and (5), n is between 1 and 50, but is preferably between 1 and 30, and more preferably between 5 and 20.

[0017] Examples of such brominated bisphenol A-based flame retardants include FireGuard 7000, FireGuard 7500, and FireGuard 8500, which are commercially available from Teijin Limited. The flame retardants mentioned above may be used individually or in combination of two or more.

[0018] Furthermore, the content of the flame retardant is preferably 0.05 to 1 by mass relative to the content of the thermally expandable graphite, more preferably 0.20 to 0.95, even more preferably 0.40 to 0.90, and still more preferably 0.60 to 0.90. By adjusting the content of the flame retardant as described above, it becomes easier to maintain the shape of the expandable heat insulating layer formed by the expansion of the thermally expandable graphite, and the fire resistance of the fire-resistant resin composition and the thermally expandable sheet made therefrom is improved.

[0019] The amount of flame retardant in the fire-resistant resin composition is not particularly limited. For example, the amount of flame retardant is preferably 5 to 300 parts by mass, more preferably 20 to 200 parts by mass, and even more preferably 40 to 150 parts by mass, per 100 parts by mass of resin. By setting the amount of flame retardant to 5 parts by mass or more, the fire resistance of the fire-resistant resin composition is improved, and by setting it to 300 parts by mass or less, the processability of the fire-resistant resin composition tends to be improved.

[0020] (Thermally expandable graphite) The fire-resistant resin composition of the present invention contains thermally expandable graphite. The thermally expandable graphite can be appropriately selected from those that satisfy the requirement that the difference between the decomposition temperature of the above-mentioned flame retardant and the expansion onset temperature of the thermally expandable graphite is 100°C or more. Thermally expandable graphite is a conventionally known substance that expands when heated. It is produced by acid-treating raw material powders such as natural scaly graphite, pyrolysis graphite, and quiche graphite with a strong oxidizing agent to generate graphite intercalation compounds. Examples of strong oxidizing agents include inorganic acids such as concentrated sulfuric acid, nitric acid, and selenic acid, as well as concentrated nitric acid, perchloric acid, perchlorates, permanganates, dichromates, and hydrogen peroxide. Thermally expandable graphite is a crystalline compound that maintains the layered structure of carbon.

[0021] The thermally expandable graphite may be neutralized. That is, the thermally expandable graphite obtained by treating it with a strong oxidizing agent as described above may be further neutralized with ammonia, aliphatic lower amines, alkali metal compounds, alkaline earth metal compounds, etc.

[0022] The expansion initiation temperature of thermally expandable graphite is preferably 150 to 350°C, more preferably 170 to 300°C, and even more preferably 180 to 280°C, from the viewpoint of maintaining a certain difference from the decomposition temperature of the flame retardant. If it is above these lower limits, it becomes easier to prevent unnecessary thermal expansion when molding the heat-resistant resin composition into a thermally expandable sheet, and if it is below these upper limits, it becomes easier to adjust the difference from the decomposition temperature of the flame retardant to a certain level.

[0023] The particle size of the thermally expandable graphite is preferably 20 to 200 mesh. If the particle size is 200 mesh or smaller, the degree of expansion of the graphite is sufficient to obtain an expanded insulating layer. If the particle size is 20 mesh or larger, the dispersibility when compounded with resin is good, and the physical properties are good. The particle size was measured using a sieve in accordance with JIS Z 8801-1.

[0024] The content of thermally expandable graphite is not particularly limited, but is preferably 50 to 200 parts by mass, and more preferably 60 to 150 parts by mass, per 100 parts by mass of resin. If it is 50 parts by mass or more, it is easier to obtain expansion suitable for preventing the passage of fire, and if it is 200 parts by mass or less, the processability of the fire-resistant resin composition and the thermally expandable sheet made therefrom is good.

[0025] (resin) The resins included in the fire-resistant resin composition of the present invention include thermoplastic resins, thermosetting resins, elastomers, rubbers, and combinations thereof. Examples of thermoplastic resins include polyolefin resins such as polypropylene resin, polyethylene resin, poly(1-)butene resin, and polypentene resin; polyester resins such as polyethylene terephthalate; polystyrene resin, acrylonitrile-butadiene-styrene (ABS) resin, ethylene vinyl acetate copolymer (EVA), polycarbonate resin, polyphenylene ether resin, (meth)acrylic resin, polyamide resin, polyvinyl chloride resin (PVC), novolac resin, polyurethane resin, and polyisobutylene.

[0026] Examples of thermosetting resins include synthetic resins such as polyurethane, polyisocyanate, polyisocyanurate, phenolic resin, epoxy resin, urea resin, melamine resin, unsaturated polyester resin, and polyimide.

[0027] Examples of elastomers include olefin-based elastomers, styrene-based elastomers, ester-based elastomers, amide-based elastomers, and vinyl chloride-based elastomers.

[0028] Examples of rubbers include natural rubber, isoprene rubber, butadiene rubber, 1,2-polybutadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, chlorinated butyl rubber, ethylene-propylene rubber, ethylene-propylene-diene rubber (EPDM), chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polyvulcanized rubber, non-vulcanized rubber, silicone rubber, fluororubber, urethane rubber, and other types of rubber. Among these, silicone rubber and fluororubber are preferred from the viewpoint of reducing the carbon content in terms of fire resistance, with silicone rubber being more preferred.

[0029] Among the thermoplastic resins, thermosetting resins, elastomers, and rubbers mentioned above, thermoplastic resins are particularly preferred from the viewpoint of improving processability. Thermoplastic resins may be used in combination with at least one of the thermosetting resins, elastomers, and rubbers, or they may be used alone. Furthermore, among thermoplastic resins, at least one selected from polyethylene resin, ethylene vinyl acetate copolymer (EVA), and polyvinyl chloride resin is preferred. Of these, polyvinyl chloride resin is more preferred from the viewpoint of lowering the carbon content in terms of fire resistance.

[0030] The polyvinyl chloride resin may be a vinyl chloride homopolymer or a vinyl chloride copolymer. The vinyl chloride copolymer is a copolymer of vinyl chloride and monomers having unsaturated bonds copolymerizable with vinyl chloride, and contains 50% by mass or more of constituent units derived from vinyl chloride. Examples of monomers having unsaturated bonds that can copolymerize with vinyl chloride include vinyl esters such as vinyl acetate and vinyl propionate, acrylic acid esters such as acrylic acid, methacrylic acid, methyl acrylate, and ethyl acrylate, methacrylic acid esters such as methyl methacrylate and ethyl methacrylate, olefins such as ethylene and propylene, aromatic vinyls such as acrylonitrile and styrene, and vinylidene chloride. Furthermore, polyvinyl chloride resin may also be polychlorinated polyvinyl chloride resin. Polychlorinated polyvinyl chloride resin is a polychlorinated polyvinyl chloride resin obtained by chlorinating vinyl chloride homopolymers, vinyl chloride copolymers, etc. Polyvinyl chloride resin may be used individually from the above-mentioned types, or two or more types may be used in combination.

[0031] The average degree of polymerization of polyvinyl chloride resin is not particularly limited, but is preferably 400 to 3000. An average degree of polymerization of 400 or higher results in good mechanical properties of the thermally expandable sheet. Furthermore, an average degree of polymerization of 3000 or lower tends to improve processability. From these viewpoints, the average degree of polymerization is more preferably 700 to 1500. The average degree of polymerization was measured in accordance with JIS K6720-2.

[0032] The total content of the above-mentioned flame retardant, thermally expandable graphite, and resin is preferably 20% by mass or more, preferably 40% by mass or more, more preferably 50% by mass or more, and preferably 95% by mass or less, preferably 90% by mass or less, and more preferably 85% by mass or less, based on the total amount of the fire-resistant resin composition.

[0033] (Organophosphorus compounds other than flame retardants) The fire-resistant resin composition of the present invention preferably contains an organophosphorus compound other than a flame retardant as a dispersant. The inclusion of the organophosphorus compound improves the fire resistance of the fire-resistant resin composition. This is thought to be because the inclusion of the organophosphorus compound allows the flame retardant to be properly positioned around the thermally expandable graphite, making it easier to maintain the shape of the expanded insulating layer, which is the expansion residue. Among organophosphorus compounds, phosphate ester compounds are preferred from the viewpoint of further improving the fire resistance of the fire-resistant resin composition.

[0034] 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 xylenyldiphenyl phosphate. Among these, trixylenyl phosphate, cresyldiphenyl phosphate, xylenyldiphenyl phosphate, and tricresyl phosphate (TCP) are particularly preferred.

[0035] The content of organophosphorus compounds is not particularly limited, but from the viewpoint of improving the dispersibility of the flame retardant and further improving the fire resistance of the fire-resistant resin composition, it is preferably 0.1 to 20 parts by mass, preferably 1 to 15 parts by mass, and more preferably 2 to 10 parts by mass per 100 parts by mass of resin.

[0036] (Inorganic fillers) The fire-resistant resin composition of the present invention preferably contains an inorganic filler. When heated, the inorganic filler increases the heat capacity and suppresses heat transfer while acting as an aggregate to improve the strength of the expanded insulating layer when an expanded insulating layer is formed. The inorganic fillers are not particularly limited and include, for example, metal oxides such as alumina, zinc oxide, titanium oxide, calcium oxide, magnesium oxide, iron oxide, tin oxide, antimony oxide, and ferrite; metal hydroxides such as calcium hydroxide, magnesium hydroxide, aluminum hydroxide, and hydrotalcite; metal carbonates such as basic magnesium carbonate, calcium carbonate, magnesium carbonate, zinc carbonate, strontium carbonate, and barium carbonate; calcium sulfate, gypsum fiber, calcium silicate and other calcium salts; silica, diatomaceous earth, dawsonite, barium sulfate, talc, clay, mica, montmorillonite, bentonite, activated clay, sepiolite, imogolite, sericite, glass fiber, glass beads, silica 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, and fly ash. Inorganic fillers may be used individually or in combination of two or more types. Among these, at least one selected from metal oxides and metal carbonates is preferred.

[0037] The particle size of the inorganic filler is preferably 0.5 to 100 μm, and more preferably 1 to 50 μm. Setting it above this lower limit prevents secondary aggregation and improves dispersibility. Setting it above the lower limit also reduces the viscosity of the refractory resin composition, making it easier to process. Setting it below the upper limit improves the surface properties and mechanical performance of the thermally expandable sheet formed from the refractory resin composition. The particle size of the inorganic filler is determined by observing the particle size distribution using a scanning electron microscope (SEM), and then using the resulting volume-based particle size distribution, the average particle size is calculated as the particle size representing 50% of the cumulative amount passing through from the smallest particle size side.

[0038] The inorganic filler content is preferably 10 to 200 parts by mass, and more preferably 15 to 150 parts by mass, per 100 parts by mass of resin. When the inorganic filler content is 10 parts by mass or more, the fire resistance of the fire-resistant resin composition is improved. When it is 200 parts by mass or less, processability is improved and it becomes easier to maintain good mechanical properties.

[0039] (Plasticizer) The fire-resistant resin composition of the present invention may contain a plasticizer. The inclusion of a plasticizer enhances the flexibility of the heat-expandable sheet and other materials formed from the fire-resistant resin composition, thereby improving processability. The plasticizer is particularly suitable when a thermoplastic resin is used as the resin, and is especially preferred when a polyvinyl chloride resin is used. Generally, plasticizers used are liquid components that are liquid at room temperature (23°C) and atmospheric pressure (1 atm).

[0040] Specific examples of plasticizers include phthalate ester plasticizers such as di-2-ethylhexyl phthalate (DOP), di-n-octyl phthalate, diisononyl phthalate (DINP), diisodecyl phthalate (DIDP), diundecyl phthalate (DUP), or phthalate esters of higher alcohols or mixed alcohols with approximately 10 to 13 carbon atoms, as well as di-2-ethylhexyl adipate (DOA), diisobutyl adipate (DIBA), dibutyl adipate (DBA), di-n-octyl adipate, di-n-decyl adipate, diisodecyl adipate, di-2-ethylhexyl azelate, dibutyl sebacate, and di-2-ethylhexyl sebacate. Examples include aliphatic ester plasticizers, trimellitic acid ester plasticizers such as tri-2-ethylhexyl trimellitate (TOTM), tri-n-octyl trimellitate, tridecyl trimellitate, triisodecyl trimellitate, and di-n-octyl-n-decyl trimellilate, biphenyltetracarboxylic acid tetraalkyl ester plasticizers such as 2,3,3',4'-biphenyltetracarboxylic acid tetraheptyl ester, polyester polymer plasticizers, epoxy plasticizers such as epoxidized soybean oil, epoxidized linseed oil, epoxidized cottonseed oil, and liquid epoxy resins, chlorinated paraffin, and chlorinated fatty acid esters such as alkyl stearate pentachloride. These plasticizers may be used individually or in combination of two or more types. Of the plasticizers mentioned above, phthalate-based plasticizers are preferred in terms of flame retardancy and cost-effectiveness. Phthalate-based plasticizers may be used alone or in combination with phosphate ester-based plasticizers.

[0041] The plasticizer content is preferably 30 to 130 parts by mass, more preferably 40 to 120 parts by mass, and even more preferably 50 to 100 parts by mass, per 100 parts by mass of resin. If the plasticizer content is above these lower limits, the flexibility of sheets formed from the fire-resistant resin composition can be increased, and the processability of the sheets can be improved. If it is below these upper limits, it is possible to prevent the sheets from becoming too soft.

[0042] The fire-resistant resin composition of the present invention may contain other components besides those mentioned above. Other components include various additives such as antioxidants (phenol-based, amine-based, sulfur-based, etc.), metal damage inhibitors, antistatic agents, stabilizers, crosslinking agents, lubricants, softeners, and pigments, as long as they do not impair the physical properties.

[0043] [Thermal expansion sheet] The heat-expandable sheet of the present invention is made of the fire-resistant resin composition described above. Thermally expandable sheets expand when heated, forming an expanded insulating layer as the thermally expandable graphite expands. This expanded insulating layer provides insulation when exposed to high temperatures, such as during a fire, and functions as a fire-resistant material. For example, a thermally expandable sheet expands 3 to 50 times after being heated at 600°C for 120 minutes. The expansion ratio is calculated as (thickness of the test specimen after heating) / (thickness of the test specimen before heating).

[0044] The thickness of the thermally expandable sheet is not particularly limited, but from the viewpoint of fire resistance and handling, 0.2 to 10 mm is preferred, and 0.5 to 3.0 mm is more preferred.

[0045] (Method for manufacturing a thermally expandable sheet) The thermally expandable sheet of the present invention can be manufactured, for example, as described below. First, a predetermined amount of resin, thermally expandable graphite, a flame retardant, and other additives as needed are kneaded in a kneader such as a kneading roll to obtain a fire-resistant resin composition. Next, if the resin is a thermoplastic resin, rubber, elastomer, or a combination thereof, the obtained fire-resistant resin composition is formed into a sheet by known molding methods such as press molding, calendering, or extrusion molding to obtain a heat-expandable sheet. If the resin includes a thermosetting resin, it is preferable to heat-cur the resulting fire-resistant resin composition into a sheet form by heating and pressurizing it, for example by press molding, to obtain a heat-expandable sheet.

[0046] (Laminated sheet) The heat-expandable sheet of the present invention may be laminated with other sheet members or adhesive layers to form a laminated sheet. The laminated sheet comprises, for example, a base material and a heat-expandable sheet laminated on one or both sides of the base material. The base material is usually a woven or nonwoven fabric. The fibers used in the woven or nonwoven fabric are not particularly limited, but non-combustible or semi-non-combustible materials are preferred, such as glass fibers, ceramic fibers, cellulose fibers, polyester fibers, carbon fibers, graphite fibers, thermosetting resin fibers, etc. The laminated sheet described above can be obtained, for example, by forming a fire-resistant resin composition into a sheet on a substrate, and, if necessary, by heat-curing the fire-resistant resin composition.

[0047] Furthermore, the laminated sheet may comprise a thermally expandable sheet and an adhesive layer. The adhesive layer may be laminated, for example, on one or both sides of the thermally expandable sheet. Furthermore, the laminated sheet may comprise a thermally expandable sheet, a substrate, and an adhesive layer. In such a laminated sheet, the thermally expandable sheet may be provided on one side of the substrate and the adhesive layer on the other side, or the thermally expandable sheet and the adhesive layer may be provided on one side of the substrate in this order. The adhesive layer can be formed, for example, by transferring an adhesive coated on release paper to the laminated sheet.

[0048] The fire-resistant resin composition, the heat-expandable sheet, and the laminated sheet made from the fire-resistant resin composition of the present invention can each be used as fire-resistant materials. Specifically, these can be used in various buildings such as detached houses, apartment buildings, high-rise buildings, commercial facilities, and public facilities, as well as various vehicles such as automobiles and trains, ships, and aircraft, but use in buildings is preferred. Specifically, in buildings, they can be used in walls, beams, columns, floors, bricks, roofs, boards, windows, shoji screens, doors, sliding doors, transoms, wiring, and piping, but are not limited to these. Because the fire-resistant resin composition of the present invention has excellent long-term fire resistance, it is particularly preferred for use in specific fire-resistant equipment, walls, beams, columns, floors, etc. [Examples]

[0049] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0050] [Evaluation Method] The decomposition temperature of the flame retardant and the expansion initiation temperature of the thermally expandable graphite were measured as follows. (Decomposition temperature of flame retardants) Measurements were performed in accordance with JIS 7120. A 10 mg sample of flame retardant was taken and used as a sample. Using a differential thermal-thermogravimetric analyzer (STA7200, manufactured by Hitachi High-Tech Science Corporation), under conditions of nitrogen gas flow rate of 75 ml / min, heating rate of 10°C / min, and measurement temperature of 100 to 800°C, the temperature at which the mass of the flame retardant decreased by 10% was defined as the decomposition temperature. (Expansion start temperature of thermally expandable graphite) 100 mg of thermally expandable graphite was taken as a sample, and using a rheometer (TA Instruments, "Discovery HR2"), the temperature was increased at a rate of 10°C / min, and the temperature at which the force in the normal direction began to rise was measured and defined as the expansion onset temperature.

[0051] The thermally expandable sheets obtained in the examples and comparative examples were measured for their expansion ratio and residue hardness. Residual hardness represents the hardness of the test specimen after heating; a higher value indicates superior fire resistance. (Expansion ratio) Test specimens (100 mm long, 100 mm wide, 1.6 mm thick) prepared from the heat-expandable sheets of the obtained examples and comparative examples were placed on the bottom surface of a stainless steel holder (101 mm square, 80 mm high), supplied to an electric furnace, and heated at 600°C for 30 minutes. After that, the height (highest part), width, length, and thickness of the test specimens were measured, and the expansion ratio was calculated by ((thickness of the test specimen after heating) / (thickness of the test specimen before heating)). (Residue hardness) The heated test specimens, whose expansion ratio was measured, were fed into a compression testing machine (Kato Tech Co., Ltd., "Finger Feeling Tester"), and compressed at a speed of 0.1 cm / second with a 1 mm diameter three-point indenter. The maximum stress up to a 10 mm compression from the top surface of the residue was measured to determine the compressive strength of the burnt test specimens. (Fire resistance) A 50mm thick calcium silicate board manufactured by A&A Material was cut to 1180mm x 1180mm in a refractory furnace, and a joint 20mm wide and 200mm long was created in the center. A 1.6mm thick, 10mm x 200mm heat-expandable sheet was attached to the side of the joint using a stable gun and iron needles. The iron needles were fixed at three points: the top and bottom ends and the center, to create a test specimen. This specimen was subjected to a 120-minute refractory test by adjusting the temperature according to the ISO 834 standard heating curve and setting the furnace pressure to 20 Pa. The specimen was observed during the refractory test, and those in which the residue of the expanding material attached to the specimen did not collapse after 120 minutes were marked with a circle (○), and those in which it collapsed and penetrated the furnace were marked with a cross (×).

[0052] (Examples 1-14, Comparative Example 1) A fire-resistant resin composition was obtained by mixing the resin, flame retardant, thermally expandable graphite, inorganic filler, plasticizer, and dispersant in a roll at 130°C for 5 minutes according to the formulation shown in Table 1 below. The obtained fire-resistant resin composition was press-molded at 130°C for 3 minutes to obtain a thermally expandable sheet with a thickness of 1.6 mm. The components used in each example and comparative example are as follows. (Examples 15-16) A resin was obtained by mixing the main component and hardener of liquid silicone rubber (ELASTOSHIL M4600, manufactured by Asahi Kasei Wacker Silicone Co., Ltd.) in a 10:1 (mass ratio) and curing it at 23°C for 12 hours. The above resin, flame retardant, thermally expandable graphite, inorganic filler, plasticizer, and dispersant were mixed in a cup according to the formulation shown in Table 1 below and stirred with a planetary stirrer. The resulting mixture was pressed at 23°C to form a 1.6 mm thick sheet and left to stand at 23°C for 12 hours to obtain a thermally expandable sheet with a thickness of 1.6 mm.

[0053] (1) Resin • PVC: Polyvinyl chloride resin, manufactured by Shin-Etsu Chemical Co., Ltd., product name "TK-1000", average degree of polymerization 1030 • Silicone rubber: Liquid silicone rubber, manufactured by Asahi Kasei Wacker Silicone Co., Ltd., product name "ELASTOSIL M4600" (2) Flame retardants • Phosphazene compound: Manufactured by Otsuka Chemical Co., Ltd., product name "SPB-100", decomposition temperature 380℃ • Organophosphorus flame retardant: Manufactured by Teijin Corporation, product name "FCX-210", decomposition temperature 360℃ • Brominated bisphenol A flame retardant: Manufactured by Teijin Limited, product name "Fireguard 7000", decomposition temperature 451℃ • Brominated bisphenol A flame retardant: Manufactured by Teijin Limited, product name "Fireguard 7500", decomposition temperature 454℃ • Brominated bisphenol A flame retardant: Manufactured by Teijin Limited, product name "Fireguard 8500", decomposition temperature 458℃ • Ammonium polyphosphate: Manufactured by Clariant Japan Co., Ltd., product name "AP422", decomposition temperature 300℃ (3) Thermally expandable graphite • Thermally expandable graphite: Manufactured by Air Water Co., Ltd., product name "CA-60N", expansion start temperature 230℃ • Thermally expandable graphite: Manufactured by ADT, product name "ADT501", expansion start temperature 150℃ (4) Inorganic fillers • Calcium carbonate: Manufactured by Shiraishi Calcium Co., Ltd., product name "BF300" • Zinc oxide: Manufactured by Sakai Chemical Industry Co., Ltd., product name "Zinc Oxide Type 1" (5) Plasticizers • DOP: Di-2-ethylhexyl phthalate, manufactured by J-Plus Co., Ltd. (6) Dispersant • TCP: Tricresyl phosphate, manufactured by Daihachi Chemical Co., Ltd.

[0054] [Table 1]

[0055] As shown in the above examples, the heat-expandable sheet made from the fire-resistant resin composition of the present invention has a high residue hardness value after heating at 600°C for 120 minutes, and is found to have excellent long-term fire resistance, because the difference between the decomposition temperature of the flame retardant and the expansion onset temperature of the heat-expandable graphite is 100°C or more. In contrast, the heat-expandable sheet of the comparative example has a low residue hardness value and is found to have poor long-term fire resistance, because the difference between the decomposition temperature of the flame retardant and the expansion onset temperature of the heat-expandable graphite is less than 100°C.

Claims

1. A fire-resistant resin composition containing a resin, thermally expandable graphite, and a flame retardant, wherein the difference between the decomposition temperature of the flame retardant and the expansion onset temperature of the thermally expandable graphite (decomposition temperature of the flame retardant - expansion onset temperature of the thermally expandable graphite) is 100°C or higher. The flame retardant is a phosphorus-based spiro compound. Furthermore, it includes an organophosphorus compound other than the aforementioned flame retardant and a plasticizer other than the aforementioned organophosphorus compound, The organophosphorus compound is one or more selected from the group consisting of trixylenyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, and tricresyl phosphate. The aforementioned plasticizer is a phthalate-based plasticizer. The content of the organophosphorus compound is 0.1 to 20 parts by mass per 100 parts by mass of the resin. A fire-resistant resin composition characterized in that the content of the phthalate-based plasticizer is 30 to 130 parts by mass per 100 parts by mass of the resin.

2. The fire-resistant resin composition according to claim 1, wherein the amount of the flame retardant is 0.05 to 1 by mass relative to the amount of the thermally expandable graphite.

3. The fire-resistant resin composition according to claim 1 or 2, further comprising an inorganic filler.

4. The fire-resistant resin composition according to claim 3, comprising 10 to 200 parts by mass of an inorganic filler per 100 parts by mass of the resin.

5. The fire-resistant resin composition according to any one of claims 1 to 4, comprising 50 to 200 parts by mass of the thermally expandable graphite per 100 parts by mass of the resin.

6. The fire-resistant resin composition according to any one of claims 1 to 5, wherein the resin is polyvinyl chloride resin.

7. A heat-expandable sheet comprising the fire-resistant resin composition according to any one of claims 1 to 6.

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