JP2005054163A - Thermal expansible fireproof composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal expansible fireproof composition which is excellent in fire resistance, thermal expansibility, shape losing preventing effect, and temperature sensitivity. <P>SOLUTION: The thermal expansible fireproof composition comprises a rubber ingredient comprising a specified amount of a thermoplastic elastomer or a flexible urethane foam, an expansible graphite, an expansible microcapsule having a lower expansion initiation temperature than the expansible graphite, boric acid, and/or an inorganic filler. The composition has a flame retardancy, can be thermally expanded at a fire and burned to give a residue with an enough retention of shape. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a novel thermally expandable fireproofing composition.

  Fireproof inflatable material or fireproof foamable material (hereinafter referred to as “fireproof inflatable material”) is used, for example, for cables such as power cables and communication cables, and coatings around piping such as air conditioners. used. These cables, pipes, and the like are arranged across a plurality of fire prevention compartments through the through holes of the fire prevention compartments.

  The part where the fire-resistant expansive material is used is expanded or foamed by heating in the event of a fire to form an expanded layer, thereby blocking the through-hole and preventing the fire from spreading. For this reason, in an inflatable material for fire prevention, expansion starts at a relatively low temperature in the event of a fire and a thermal insulation effect is exhibited by the expansion layer. After the formation of the expansion layer, the expansion layer is not easily deformed by flame heat, The condition is that the shape can be maintained for as long as possible.

  In this regard, for example, an inorganic expansion agent and / or an organic expansion agent and a resin for preventing deformation such as polycarbonate resin, polyphenylene sulfide resin, polyether ketone resin, polyamide resin, and phenol resin are blended in the base resin at the same time. An intumescent resin composition for fire prevention or the like characterized by this is known (see, for example, Patent Document 1). According to this fire-resistant intumescent composition, since the resin for preventing deformation is blended in particular, it is said that the expansion layer does not lose its shape even when subjected to flame heat and can continue to retain its shape. ing.

  However, since the above-mentioned inflatable composition for fire prevention melts and then burns out, the resin for preventing deformation does not provide sufficient fire resistance during the fire, or the intumescent layer is easily pulverized and after the fire This will interfere with the processing. In addition, the shape-preventing resin is relatively expensive and has a problem in terms of cost. Depending on the application, there is a problem that elasticity and flexibility are not sufficient.

  On the other hand, as a technique for imparting fire resistance to polyurethane having elasticity and flexibility, there is known a method for producing a fire-resistant elastic polyurethane flexible foam in which expansive graphite is blended as a flame retardant with a polyol and a polyisocyanate. (For example, see Patent Document 2)

  However, the manufacturing method described above is still insufficient in the effect of preventing deformation. Moreover, in the above technique for producing polyurethane from a two-component reaction mixture of a polyol and a polyisocyanate, it is extremely difficult to blend a large amount of expansive graphite, and sufficient fire resistance cannot be obtained. In other words, in order to give better fire resistance, it is necessary to add as much expandable graphite and shape change prevention agent as possible, but the above technique increases the slurry viscosity, and the production of the desired polyurethane itself. Becomes difficult.

As a technique for solving these problems, a composition in which expansive graphite and boric acid as a shape loss preventing agent are blended with rubber or flexible urethane foam is disclosed (for example, Patent Documents 3 and 4). There is a demand to start expansion at a temperature lower than the temperature so as to impart heat insulation quickly, or to quickly block the gap by expansion to prevent the inflow of smoke.
JP-A-9-176498 (second page: claims 1 to 4) Patent No. 2732435 (first page: claims 1-9, second page claims 10-12) JP 2001-348487 A (2nd page: claims 1 to 5) JP 2001-348476 A (2nd page: claims 1 to 8)

  As described above, a material that sufficiently satisfies the fire resistance performance including the deformation preventing effect, has both elasticity and flexibility, and has a secondary expansion at a higher temperature after a primary expansion at a predetermined temperature has not yet been developed. Is the current situation.

  As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.

  That is, the present invention comprises a rubber component containing a specific amount or more of a thermoplastic elastomer, or a flexible urethane foam, and expandable graphite, expandable microcapsules, boric acid, and / or an inorganic filler, and has flame retardancy. It has thermal expansion in the event of a fire, and is excellent in temperature sensitivity and expands at a relatively low temperature to prevent combustion gas and smoke from flowing through the gaps in the through-holes, and the residue after combustion has a sufficient shape The present invention relates to an unprecedented novel thermally expandable fireproofing composition.

  According to the composition of the present invention, in particular, the combination of boric acid, thermally expandable graphite, and thermally expandable microcapsules having a lower expansion start temperature than expandable graphite can exhibit fire resistance superior to that of the prior art. it can. In other words, expandable microcapsules are exposed to high temperatures for a long time due to their excellent temperature sensitivity, which expands at relatively low temperatures, and expandable graphite forms an expanded layer at high temperatures and prevents boric acid from collapsing. Are also less vulnerable. As a result, excellent fire resistance can be stably obtained even in a fire. Moreover, since the expansion layer is not easily broken even after a fire, the post-fire treatment can be performed smoothly and safely.

Hereinafter, the present invention will be described in detail.
The rubber component used in the present invention includes ethylene propylene rubber, butyl rubber, styrene butadiene rubber, isoprene rubber, acrylonitrile butadiene rubber, polybutadiene rubber, chloroprene rubber, polybutene rubber, chlorinated polyethylene rubber, acrylic rubber, chlorosulfonated polyethylene, silicone Rubber, fluororubber, natural rubber and thermoplastic elastomer can be used.

  These rubber components can be used in a blend of two or more to improve kneadability, sheet formability, extrusion formability, press formability, etc. Further, the dimensional stability of such molded products is maintained and molded. In order to provide a balance between strength and flexibility when the product is mounted on the two-layer tube, it is preferable to use the rubber component containing at least 20% by mass or more of a thermoplastic elastomer. If it is less than 20% by mass, the moldability, strength and dimensional stability of the molded product are not sufficient.

  The effect of adding thermoplastic elastomer is that the hard segment in the thermoplastic elastomer melts and develops fluidity at the time of molding, and the moldability is exerted. On the other hand, the soft segment in the thermoplastic elastomer exhibits rubber elasticity at room temperature. In addition to exerting an effect on the strength and flexibility, the hard segment improves the dimensional stability of the molded product. In the event of a fire, the hard segment melts due to heat and plays a role in temporarily holding the thermally expanded expansive graphite.

  As the thermoplastic elastomer used in the present invention, various thermoplastic elastomers such as vinyl chloride thermoplastic elastomer, styrene thermoplastic elastomer, polyolefin thermoplastic elastomer, and polyester thermoplastic elastomer can be used. Of these, styrene thermoplastic elastomers are particularly preferred.

  The styrenic thermoplastic elastomer is a block copolymer composed of a polymer block mainly composed of a vinyl aromatic compound and a polymer block mainly composed of a conjugated diene compound. Examples of the vinyl aromatic compound include styrene, p -Methyl styrene, (alpha) -methyl styrene, vinyl xylene, monochloro styrene, dichloro styrene, monobromo styrene, etc. are mentioned, These are used individually or in combination of 2 or more types. Of these, styrene is particularly preferred.

  Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene and the like, and these are used alone or in combination of two or more. Of these, preferred are 1,3-butadiene and isoprene, and particularly preferred is 1,3-butadiene.

  The block copolymer of styrenic thermoplastic elastomer used in the present invention is produced by known anionic polymerization.

  As the flexible urethane foam used in the present invention, those obtained from any raw material such as a one-pack type or a two-pack type can be used, but the one-pack type is particularly preferable. As the one-pack type, for example, a flexible urethane foam obtained from an aqueous urethane prepolymer can be suitably used.

  In the case of using an aqueous urethane foam, the slurry can be prepared by first adding water to expansive graphite and boric acid, and then mixing the aqueous urethane prepolymer with the slurry, followed by foam curing. The slurry concentration can be appropriately set according to the purpose and application of the final product, but is usually 20 to 90% by mass, preferably 50 to 70% by mass. When there is too much water, there exists a possibility that the shape stability of the molded object obtained may fall. Moreover, when there is too little water, since the viscosity of a slurry rises, a desired foaming hardening body may not be obtained.

  Moreover, another additive can also be mix | blended with a slurry as needed. For example, a surfactant, a crosslinking agent, a foam stabilizer, a catalyst, a foaming agent, a flame retardant, a stabilizer, an ultraviolet absorber, an antioxidant, a pigment, a filler, and the like can be used. After mixing these components simultaneously or sequentially, the slurry is uniformly mixed with a known stirrer or the like. The aqueous urethane prepolymer is then added to the slurry and stirring and mixing is continued until foaming begins. If necessary, it is poured into a mold having a predetermined shape and foamed and cured. The obtained molded body is cured as necessary at, for example, about 50 ° C. to evaporate the contained water, thereby obtaining a foam cured body having excellent shape stability. These curing times may be appropriately set according to the curing temperature, the size of the foam cured body, and the like.

  The expandable graphite used in the present invention is not particularly limited. Expandable graphite is a powder of natural graphite, pyrolytic graphite, etc., treated with an inorganic acid such as sulfuric acid or nitric acid and a strong oxidizing agent such as concentrated nitric acid or permanganate, and is a crystalline compound that maintains a graphite layered structure. It is. When exposed to temperatures of about 200 ° C. or higher, it expands by a factor of 100 or more. In addition to the deoxidation treatment, there are various varieties such as a neutralized type powder, and any powder can be used.

  The particle size is preferably about 20 to 400 mesh. When the particle size is smaller than 400 mesh, the thermal expansion degree of graphite is small, and when the particle size is larger than 20 mesh, dispersibility deteriorates when kneaded into rubber, and physical properties such as strength are inevitably lowered.

  The content of expandable graphite can be appropriately set depending on the type of rubber component or flexible urethane foam, the desired expansion ratio, etc., but usually 5 to 100 parts by mass with respect to 100 parts by mass of the rubber component or flexible urethane foam. use. When the amount is less than 5 parts by mass, the thermal expansion ratio at the time of fire occurrence is low. If the amount exceeds 100 parts by mass, the thermal expansion ratio increases, but the hardness of the resulting compound increases and the physical properties such as strength also decrease. In the case of sheet forming, the formability is inferior and the surface skin is deteriorated.

  The expandable microcapsule used in the present invention is a plastic microsphere (average particle diameter: 5 to 50 μm) in which a low-boiling liquid or solid or a compound that generates a gas upon heating is encapsulated in a thermoplastic resin shell. As a result, the shell softens, and at the same time, the encapsulated substance gasifies or generates gas, and the capsule expands. Examples of the substance to be included include low-boiling hydrocarbons and bicarbonates such as sodium bicarbonate, and low-boiling hydrocarbons are particularly preferable for this application.

  The expansion start temperature is variously designed according to the resin composition as the shell, but those having a property of 70 ° C to 170 ° C can be used. For the selection of the expansion start temperature, a temperature lower than the expansion start temperature of the expandable graphite used together is used. At the time of heating, the expandable microcapsules start to expand, and then expandable graphite starts to expand as the temperature rises. As a result, the inflow of smoke and gas generated during the initial heating can be blocked, and a foamed layer can be formed by the initial expansion to exhibit a heat insulating effect.

  The content of the expandable microcapsule is usually 5 to 100 parts by mass with respect to 100 parts by mass of rubber. When the amount is less than 5 parts by mass, the thermal expansion ratio during heating is small. Exceeding 100 parts by mass is not preferable because the thermal expansion ratio increases, but the cost increases. The mass ratio between the expandable graphite and the expandable microcapsule is preferably 1: 1 to 10: 1, more preferably 1: 1 to 5: 1.

As the inorganic type collapse preventing agent used in the present invention, boric acid is used. As boric acid itself, a product obtained by a known production method or a commercially available product can be used. The boric acid may be any of orthoboric acid (H ₃ BO ₃ ), metaboric acid (HBO ₂ ), etc., but orthoboric acid is usually used. Boric acid is usually used in powder form. In this case, the particle size of the powder is not particularly limited, but a powder having a relatively small particle size (usually about 100 μm or less, preferably about 20 μm or less) is preferable.

  The content of boric acid can be appropriately set depending on the amount of expansive graphite used, but usually 10 to 200 parts by mass with respect to 100 parts by mass of rubber. When the amount is less than 10 parts by mass, the effect of holding the expandable graphite is small, and the deformation prevention performance is inferior. Moreover, when it exceeds 200 mass parts, since the hardness of a compound becomes high and flexibility is inferior, it is unpreferable.

  The ratio of boric acid and expandable graphite is preferably 1: 5 to 10: 1 by mass ratio, more preferably 1: 2 to 5: 1 in consideration of the balance of formability, strength characteristics and the like.

  The inorganic filler used in the present invention improves moldability and the like. Silica, diatomaceous earth, alumina, zinc oxide, titanium oxide, magnesium oxide, iron oxide, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, hydrotalcite, calcium sulfate, barium sulfate, silicic acid Calcium, talc, clay, mica, bentonite, activated clay, sepiolite, glass fiber, glass beads, aluminum nitride, boron nitride, carbon black, graphite, carbon fiber and the like can be used. Two or more of these may be used in combination. The particle size is preferably 1 to 50 μm from the viewpoint of dispersibility in rubber.

  Among the above inorganic fillers, aluminum hydroxide and magnesium hydroxide are preferable because they are endothermic due to water generated by the dehydration reaction during heating, and the flame retardancy is improved in that the temperature rise is suppressed. In particular, aluminum hydroxide is inexpensive and easy to use.

  The inorganic filler is used by adding 10 to 300 parts by mass with respect to 100 parts by mass of the rubber component. When the amount is less than 10 parts by mass, the effect of improving sheet formability and punchability is small. Use exceeding 300 parts by mass is not preferable because the hardness of the composition is increased, flexibility is inferior, and strength properties are also deteriorated.

  Furthermore, in the present invention, plasticizers, softeners, anti-aging agents, processing aids, lubricants, tackifiers, vulcanizing agents and the like generally used for rubber can be used in combination as appropriate.

  The rubber compound can be obtained by kneading the above components using a kneading apparatus such as a known mixer, Banbury mixer, kneader mixer, two rolls, etc., and using this, press molding, roll molding, A molded product can be obtained by a conventionally known molding method such as extrusion molding or calendar molding.

  The composition of the present invention can be used in any form. For example, it can be formed into a sheet shape, a tape shape, a granular shape, or can be used in a putty shape.

  EXAMPLES The present invention will be specifically described below with reference to examples, but these examples do not limit the present invention. In addition, the part and% in the following description are based on a mass reference | standard.

"Examples 1-8""Comparative Examples 1-7"
In the examples and comparative examples, the following materials were used.
a. Rubber: Butyl rubber (manufactured by JSR Corporation, “Butyl 268”), EPDM (manufactured by DSM Japan Co., Ltd., “Keltan 2630A”), SBS (JSR Shell Corporation, “Clayton D1011”).
b. Aqueous urethane prepolymer: (Mitsui Chemicals, "EGH-401")
c. Expandable graphite: (manufactured by Sumikin Chemical Co., Ltd., “SS-3” expansion start temperature 260 ° C., “50 LTE-U” expansion start temperature 170 ° C.).
d. Expandable microcapsules: (Matsumoto Yushi Seiyaku Co., Ltd. “F-793” expansion start temperature 110 ° C., “H-850” expansion start temperature 155 ° C., “M-330” expansion start temperature 105 ° C.).
e. Boric acid: (BOR)
f. Inorganic filler: (Showa Denko Co., Ltd., "Hijilite H-42").
g. Softener: Naphthenic oil (manufactured by Idemitsu Kosan Co., Ltd., “NP-24”).
h. Processing aid: (Riken Vitamin Co., Ltd., “Emaster 510P”).

(1) Rubber component-containing composition A heat-expandable fireproofing composition was prepared by uniformly kneading the components shown in Table 1 using a 3 liter kneader. Subsequently, each mixture was formed into a sheet shape having a thickness of 8 mm with a roll. About each Example, the thermal expansibility at the time of heating and shape retainability were evaluated with sheet moldability, hardness, and flexibility. The results are shown in Table 1.
(2) Aqueous urethane prepolymer-containing composition Water was added to a mixture of boric acid, expansive graphite, and expansive microcapsules in the amount shown in Table 2 to prepare a slurry. Aqueous urethane prepolymer was added to this slurry, mixed with stirring, poured into a mold having dimensions of 12 cm × 12 cm × 17 cm, foam-molded, cured in an oven at 100 ° C. for 1 hour, and then demolded. The obtained foamed cured product was further cured in an oven at 50 ° C. for 2 days to evaporate the water and obtain a sponge-like molded product.

  The composition obtained in each example was evaluated for hardness, thermal expansibility, and shape retention. The results are shown in Table 2.

The measuring method of each physical property is shown below.
Sheet formability: The obtained kneaded material was formed into a sheet having a thickness of 8 mm with a roll, and the appearance and the like of the obtained sheet were observed. A sheet having no problems such as cracks was evaluated as ◯, a sheet having cracks, tears or the like was evaluated as Δ, and a kneaded product adhered to the roll and could not be formed into sheets.
Surface hardness: Measured by reading an instruction immediately after applying a C-type rubber hardness meter (manufactured by Kobunshi Keiki Co., Ltd.) to the sheet molding.
Flexibility: 8mm thick sheet formed on a roll is punched into No. 1 dumbbell, both ends are lifted to a 45 degree angle, the degree of cracking when bent, ○ (good) when there is no crack, crack The case where there was was evaluated as x (bad).
Thermal expansibility: Inserted and installed with the upper 20 mm protruding so that the lower 50 mm of the test piece is buried between the 10 mm gap between the refractory bricks and the refractory bricks. , Heat treatment at 200 ° C. and 300 ° C. for 0.5 hours. When the gap of 10 mm was completely closed, it was evaluated as ◯ (good), otherwise x (bad), and the middle was evaluated as Δ.
Shape retention: Using a thermal expansion evaluation jig, the shape stability and degree of deformation after heat treatment at 300 ° C. for 0.5 hours of a 20 mm test piece protruding upward was evaluated by touch and visual observation. The evaluation was ○ when the shape was not easily deformed by a finger touch and the deformation was small, and × when the shape was deformed immediately after touching the finger.
The results are summarized in Tables 1 and 2.

Claims (7)

  From a rubber component and / or a flexible urethane foam containing at least 20% by mass or more of a thermoplastic elastomer, expansive graphite and expansive microcapsules as a thermal expansion agent, boric acid and / or an inorganic filler as an inorganic deformation preventing agent A thermally expandable fireproofing composition characterized by comprising:   2. The heat-expandable fireproofing according to claim 1, wherein the thermoplastic elastomer is a styrenic elastomer comprising a polymer block mainly composed of a vinyl aromatic compound and a polymer block mainly composed of a conjugated diene compound. Composition.   The heat-expandable fireproofing composition according to claim 1, wherein the flexible urethane foam is obtained from an aqueous urethane prepolymer.   5 to 100 parts by mass of expandable graphite, 5 to 100 parts by mass of thermally expandable microcapsules, 10 to 200 parts by mass of boric acid, and / or 10 to 300 parts by mass of an inorganic filler with respect to 100 parts by mass of the rubber component or flexible urethane foam. The heat-expandable fireproofing composition according to any one of claims 1 to 3, wherein the heat-expandable fireproofing composition according to any one of claims 1 to 3 is formed.   The expansion start temperature of the expandable microcapsule is 70 ° C to 170 ° C, and the expansion start temperature is lower than that of the expandable graphite, The thermally expandable fire prevention according to any one of claims 1 to 4, Composition.   The thermally expandable fireproofing composition according to any one of claims 1 to 5, wherein the inorganic filler is aluminum hydroxide. The mass ratio of boric acid and thermal expansion agent is 1: 5 to 10: 1, and the mass ratio of expandable graphite to expandable microcapsules is 1: 1 to 10: 1. The composition for heat-expandable fire prevention described in any one of 1-6.