JP2005048942A - Joint material for fire-proof bilayer pipe and gasket composed of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint material for a fire-proof bilayer pipe superior in mounting workability, durability, flexibility and fire-retardant property, with respect to the joint material for the fire-proof bilayer pipe used in a fire-proof bilayer pipe connecting part. <P>SOLUTION: Expandable graphite, boric acid and inorganic filler are added and blended to a rubber component including a specific amount of thermoplastic elastomer, to prepare the joint material for the fire-proof bilayer pipe using a flexible fire-retardant rubber having flame retardancy, being thermally expanded when the fire breaks, and having sufficient shape retentivity in a residue after combustion. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a joint material for a fire-resistant double-layer pipe used in a connecting portion when connecting a fire-resistant double-layer pipe composed of an inner pipe and a fire-resistant outer pipe covering the inner pipe, and a gasket comprising the joint material for the fire-resistant double-layer pipe About.

  Water / drainage pipes, gas pipes, power distribution pipes, etc. penetrate through fire prevention compartments of building structures, and hard vinyl chloride pipes are widely used especially for water supply / drainage pipes. However, it has been obliged to use non-combustible materials such as metal and cement mortar for these piping materials and joint materials when connecting them according to the Building Standard Law. Based on this rule, cemented mortar, water glass, metal bands, non-combustible joints are used for inner pipes made of synthetic resin such as hard vinyl chloride pipes and fireproof double-layer pipes made of cladding tubes such as fiber reinforced mortar. Inorganic fiber gaskets and the like are used.

  However, in a so-called wet joint method using cement or water glass as a main raw material, the joint material applied to the joint portion may be cured with time to cause cracks and peeling, thereby inducing dropout of the joint material. In addition, deterioration due to carbonation may be caused, and it may be difficult to secure a function as a stable joint treatment over a long period of time. When a paste-like joint material filled into a tube or tape-like is used, the waterproof property is poor, and there is a problem that it softens due to rain water.

  On the other hand, in the dry joint method using a metal joint cover at the joint of a refractory double-layer pipe, the dimensional shape is set in advance. It may be difficult to respond to the problem and may cause problems in workability. Moreover, since heat insulation is inferior, it may condense and corrode a metal especially when used for a water supply pipe. Moreover, there is a problem that the stainless steel band is expensive.

  Furthermore, in these joint methods, after the piping work to the building is completed, the work space is limited, and the work is cumbersome and it is difficult to secure a uniform joint processing function, and there is a possibility that the joint processing part may be overlooked. is there. In addition, the construction period may be prolonged, which may increase the cost. In addition, there is a risk of refractory fire-resistant double-layer pipes being damaged due to changes in length of the fire-resistant double-layer pipes due to earthquakes, building vibrations and moisture, and temperature changes.

As for the inorganic gasket, a joint structure (for example, see Patent Document 1) or a fiber material in which an annular packing made of non-flammable inorganic heat insulating fiber such as ceramic fiber, glass fiber, rock wool fiber, silica fiber or the like is interposed in a compressed state. There is a method for producing a nonflammable fireproof packing made of an admixture and a connecting material (see, for example, Patent Document 2). However, these are fragile and have a problem that they are easily cracked during installation, and are also expensive. Moreover, a flexible fireproof rubber joint material composed of rubber, expansive graphite, epoxy resin and inorganic filler is disclosed (see, for example, Patent Document 3), and the brittleness and fire resistance which have been the conventional problems are disclosed. Although improved, there has been a problem that the epoxy resin blended for imparting the function of holding the expandable graphite under high temperature adheres to the inner wall of the kneading machine during kneading, and this removal is extremely difficult. In addition, shape retention at high temperatures was not always sufficient. Although the composition of the present invention has already been disclosed (see Patent Document 4), it has not been known so far that a remarkable effect can be obtained when used in the application of the present invention.
JP-A-7-301393 (second page: claims 1 to 12) Japanese Patent Laid-Open No. 10-281294 (second page: claim 1) JP 2002-181262 A (page 2: claim 1) JP 2001-348487 A (2nd page: claims 1 to 4)

  Fire resistance performance is one of the most important performances in the field of building materials, but in recent years, fire resistance performance is not only that the material itself is difficult to burn, but also that the flame does not turn to the back of the member, that is, fire resistance performance. It is requested. The rubber component and organic component have the property of burning or melting by nature, so how long it can be prevented from being in such a state, or how to contain an inorganic component An important factor is whether the inorganic component can be retained for a long time without dropping off.

  The present invention solves the above-mentioned problems of the prior art, has good moldability and has the above fireproof performance, i.e., thermal expansion in the event of a fire, and the residue after combustion has sufficient shape retention. The present invention provides an inexpensive joint material that is insoluble in condensed water and maintains a certain shape.

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

  The present invention relates to a joint material for a refractory double-layer pipe and a gasket comprising the joint material for the refractory double-layer pipe used for a connecting portion of the fire-resistant double-layer pipe, a rubber component containing a specific amount or more of thermoplastic elastomer, expansive graphite, boron An unprecedented new flexible fireproof rubber that consists of an acid and an inorganic filler, has flame retardancy, expands thermally in the event of a fire, and has sufficient shape retention after combustion. It is characterized by using.

  The fireproof double-layer pipe joint material of the present invention and the gasket made of the fire-resistant double-layer pipe joint material are flexible materials obtained by adding expansive graphite, boric acid and an inorganic filler to a rubber component containing a specific amount or more of a thermoplastic elastomer. By using a fireproof rubber, it is possible to obtain an inexpensive joint material that has good moldability, expands thermally in the event of a fire, and has sufficient shape retention properties after combustion.

  Hereinafter, the present invention will be described in detail.

  The rubber components used in the present invention are 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. Fluorine rubber, 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. In addition, while maintaining the dimensional stability of such molded products, molding is possible. 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, the hard segment improves the dimensional stability of the molded product while exerting an effect on strength and flexibility. 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 a vinyl chloride thermoplastic elastomer, a styrene thermoplastic elastomer, a polyolefin thermoplastic elastomer, and a 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 -Methylstyrene, (alpha) -methylstyrene, vinyl xylene, monochlorostyrene, dichlorostyrene, monobromostyrene 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 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.

  The expandable graphite used in the present invention is not particularly limited. Expandable graphite is a crystalline compound in which powders of natural graphite, pyrolytic graphite, etc. are treated with inorganic acids such as sulfuric acid and nitric acid and strong oxidizing agents such as concentrated nitric acid and permanganate, and maintain a graphite layered structure. When it is exposed to a temperature of about 200 ° C. or higher, it expands by a factor of 100 or more. In addition to the deoxidation treatment, there are various types of powders, 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 cannot be reduced.

  The content of expandable graphite can be appropriately set depending on the type of rubber component, desired expansion ratio, etc., but usually 5 to 100 parts by mass is used for 100 parts by mass of rubber. When the amount is less than 5 parts by mass, the thermal expansion ratio at the time of fire is small. When the amount exceeds 100 parts by mass, the thermal expansion ratio increases, but the hardness of the resulting rubber compound increases and physical properties such as strength also decrease. Moreover, sheet formability is inferior and the surface skin of the ring becomes worse.

  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 (H3BO3), metaboric acid (HBO2), etc., but orthoboric acid is usually used.

  Boric acid is usually used in powder form. In this case, the particle diameter of the powder is not particularly limited, but a powder having a relatively small particle diameter (usually about 100 μm or less, preferably about 20 μm or less) can be preferably used.

  The content of boric acid can be appropriately set depending on the amount of expansive graphite used, but usually 10 to 100 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 100 mass parts, since the hardness of a compound becomes high and flexibility is inferior and it becomes easy to bend at the time of the mounting | wearing operation | work to a fireproof two-layer pipe | tube, it is unpreferable.

  The ratio of boric acid and expansive graphite is preferably 1: 3 in terms of mass ratio, taking into account the balance of sheet formability at the time of manufacture, punchability into a ring shape, flexibility of the product ring, waterproofness, strength characteristics, and the like. 5-10: 1, more preferably 1: 2-5: 1.

  Examples of the inorganic filler used in the present invention include silica, diatomaceous earth, alumina, zinc oxide, titanium oxide, magnesium oxide, iron oxide, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, hydro Talsite, calcium sulfate, barium sulfate, calcium silicate, talc, clay, mica, bentonite, activated clay, sepiolite, glass fiber, glass beads, aluminum nitride, boron nitride, carbon black, graphite, carbon fiber, etc. can be used, Improve sheet formability, punchability to ring shape, etc. 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 in an amount of 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. When the amount exceeds 300 parts by mass, the hardness of the ring product obtained by increasing the hardness of the sheet is inferior, and the strength characteristics 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 each of the above components using a known kneading apparatus such as a Banbury mixer, a kneader mixer, a two roll, etc., for example, press molding, roll molding, extrusion molding, A flexible fireproof rubber sheet can be obtained by a conventionally known molding method such as calendar molding. Further, this sheet is punched into a ring shape by using a conventionally known device having a punching blade to obtain a joint material for a fireproof double-layer pipe. The joint material for this fireproof double-layer pipe is generally an insertion type in which a ring-shaped molded product is incorporated into the double-layered tube at the time of construction. However, when the double-layered tube is manufactured, the tape-shaped molded product is used as the vinyl chloride inner tube. It is also possible to manufacture a fire-resistant double-layered tube that is pre-wound and integrally molded with a cement mortar outer tube.

  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 1-3""Comparative Examples 1-4"
In the examples and comparative examples, the following materials were used.
(1) Rubber: Butyl rubber (manufactured by JSR Co., Ltd., Butyl 268), EPDM (manufactured by DSM Japan Co., Ltd., Keltan 2630A), SBS (JSR Shell Co., Ltd., Clayton D1011).
(2) Expandable graphite (manufactured by Sumikin Chemical Co., Ltd .: SS-3).
(3) Boric acid (BOR)
(4) Inorganic filler (manufactured by Showa Denko KK: Hijilite H-42; aluminum hydroxide Al (OH) 3).
(5) Softener: Naphthenic oil (manufactured by Idemitsu Kosan Co., Ltd .; NP-24).
(6) Processing aid (Riken Vitamin Co., Ltd .: Emaster 510P; glycerin fatty acid ester).

  The above components were kneaded using a 3 liter kneader and formed into a sheet having a thickness of 5 mm on a two-roll. A test piece was punched out of a hot sheet at about 80 to 100 ° C. into a dimension of 5 mm thickness × 50 mm width × 70 mm length with a punching blade. Immediately immersed in water for 10 seconds and cooled. Thereafter, it was taken out, air-dried, and further dried in a gear oven at 50 ° C. for about 3 hours.

  The above sheet was evaluated for flexibility, water resistance, moldability, thermal expansibility, and shape retention, and the tensile stress and hardness of each sheet press-molded as described below were evaluated by the following methods.

  Tensile stress: A press-molded 5 mm thick sheet was punched into a No. 3 dumbbell and pulled at a speed of 500 mm / min to obtain the maximum stress.

  Hardness: About the said sheet | seat, the durometer A hardness meter was used and the value immediately after pressing was read.

  Flexibility: punched into a No. 1 dumbbell from a 5mm thick sheet molded on a roll, lifted both ends to a 45 degree angle, the degree of cracking when bent, ○ (good) when no crack, crack The case where there was was evaluated as x (bad).

  Formability: ◯ (good) if the dimensional change of the thickness, width and length of the test piece is 2% or less, △ if it is 2-5%, △ (bad) if it is 5% or more. evaluated.

  Thermal expansion: 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 brick and the refractory brick, and kept in this state at 300 ° C. for 1 hour. Heat treated. When the gap of 10 mm was completely closed, it was evaluated as ◯ (good), and otherwise it was evaluated as x (bad).

  Shape retention: Using a thermal expansibility evaluation jig, the shape stability and degree of deformation after heat treatment at 300 ° C. for 1 hour of a 20 mm test piece protruding upward was evaluated by touch and visual observation. The evaluation was ○ when the shape was difficult to be deformed by finger touch and the deformation was small, × when the shape was deformed and deformed immediately by touch, and Δ was the middle. The results are summarized in Tables 1 and 2.

Claims (6)

  A rubber component containing at least 20% by mass or more of a thermoplastic elastomer, which is used between the opening end edge of the outer tube of the fireproof double-layer tube and the opening end edge of the outer tube of the pipe joint opposite to the outer tube, thermal expansion A joint material for refractory double-layer pipes, comprising expansive graphite as an agent, boric acid and an inorganic filler as an inorganic deformation preventing agent.   2. The joint for a refractory double-layer pipe according to claim 1, wherein the thermoplastic elastomer is a styrene-based elastomer comprising a polymer block mainly composed of a vinyl aromatic compound and a polymer block mainly composed of a conjugated diene compound. Wood.   The rubber component is composed of 5 to 100 parts by mass of expansive graphite, 10 to 100 parts by mass of boric acid, and 10 to 300 parts by mass of an inorganic filler, and the total is 500 parts by mass or less. The joint material for fireproof double-layer pipes according to claim 1.   The joint material for fireproof double-layer pipe according to claim 1, wherein the inorganic filler is aluminum hydroxide.   The joint material for fireproof double-layer pipe according to any one of claims 1 to 4, wherein a mass ratio of boric acid and expansive graphite is 1: 5 to 10: 1. The gasket which consists of the joint material for fireproof two-layer pipes of any one of Claim 1 to 5.