Flame-retardant heat-insulating pipe and pipe joint

Abstract

To provide a flame-retardant heat-insulating pipe and a pipe joint that exhibit superior flame retardancy and thermal insulation, have favorable flexibility, and suppress evaporation and scattering of condensed moisture.SOLUTION: A flame-retardant heat-insulating pipe H1 includes a pipe main body 1 formed of a flexible bendable pipe, a foam layer 2 made of an elastically deformable foamed material obtained by laminating, so as to cover an outer side of the pipe main body 1, a sheet-like material having a closed-cell foamed structure that is produced by extrusion molding a mixture containing a thermoplastic resin and a flame retardant and subjecting the mixture to chemical foaming or physical foaming, and a protective layer 3 made of a protective film laminated so as to cover an outer side of the foam layer. The foamed material has a tear strength in an extrusion direction of extrusion molding of 15 N / cm or more as measured in accordance with JIS-K-6767, and a residual elongation ratio after 100% tensile elongation in the extrusion direction of 10% or less, and the pipe main body 1 and the foam layer 2 are non-adhesively laminated and are laminated so as to be freely movable relative to each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a flame-retardant thermally insulated pipe that has excellent heat insulation and flame retardancy and good flexibility and is used in fields such as semiconductor manufacturing, medicine, the food industry, and industrial parts, and to a pipe fitting optimized for the flame-retardant thermally insulated pipe of the present invention. [Background technology]

[0002] Tubes and hoses used in fields such as semiconductor manufacturing, medicine, the food industry, and industrial parts require thermal insulation to prevent the quality of the transported fluids, such as chemical raw materials, from deteriorating due to temperature changes and to prevent energy loss, and for this reason, thermally insulated pipes coated with foam are used.

[0003] Furthermore, there is an increasing need to make devices, factory equipment, and their components flame-retardant in order to prevent the spread of fire and damage in the event of a fire in a building or factory. Generally, foamed sheets or tubes made of foamed polyolefin resins such as polyethylene are used as the covering material for the thermal insulation pipe. However, these are flammable, and therefore, foamed materials containing flame retardants are used instead to meet the demand for flame retardancy.

[0004] As an example, semiconductor manufacturing requires the use of clean rooms. Semiconductor chip processing equipment and other equipment in clean rooms, such as wet benches and wafer storage cabinets, must pass certain ignition tests. Factory Mutual Research Corporation (FMRC) has proposed an ignition standard for clean room equipment entitled "FMRC Clean Room Materials Flammability Test Protocol" (Second Revision, February 1997) ("FM4910 Standard"). Recommendations relevant to this invention are found in Loss Prevention Data, Semiconductor Manufacturing Facilities (Factory Mutual Engineering Corporation, 1997), Section 2.4, "Process Tools and Product Storage." Section 2.4.1 of this publication requires that new wet benches and other process tools be constructed of non-flammable materials. "Current wet benches constructed of combustible materials that process corrosive products should be replaced with wet benches that comply with Section 2.4.1" (Section 2.4.3). "Non-combustible materials, or materials that meet the criteria of the FMRC Cleanroom Materials Ignition Test Method per FMRC Standard Test, should be used to enclose the mini-environment" (Section 2.4.6).

[0005] If a fire breaks out in a cleanroom, damage can occur from fire, smoke, and / or corrosive combustion by-products. Even if the fire damage is minimal, the smoke and corrosive combustion by-products can destroy products, cleanroom processing fixtures, and other equipment. Therefore, even a small fire can cause significant financial losses. Materials that meet the FM4910 standard can be fabricated into semiconductor chip processing fixtures and cleanroom fixtures without the need for additional fire detection and suppression equipment, also known as fixed fire protection. This is desirable because false alarms from fire protection equipment can result in loss of wafer production and therefore financial losses. Therefore, materials that meet the FM4910 standard are preferred for use in semiconductor chip processing fixtures and cleanroom fixtures.

[0006] A variety of materials have been used in the manufacture of semiconductor chip processing fixtures and clean room fixtures. Thermoplastic materials such as polyvinylidene fluoride (PVDF), perfluoroalkoxy (PFA), polyetheretherketone (PEEK), and polytetrafluoroethylene (PTFE) have been used. These thermoplastic materials meet the FM4910 standard and therefore can be used without additional fire detection and suppression equipment, but they are relatively expensive polymers.

[0007] Polyolefin materials such as polypropylene have also been used in semiconductor chip processing fixtures and cleanroom fixtures. In semiconductor applications, polypropylene, FR-polypropylene, and PVC are not used for wetted parts or primary process chemical containment. These materials are used as structural materials in the construction of corrosive, wetted tooling. They typically comprise plastic boxes housing process vessels, chemical delivery equipment, robots, etc. They also function as process vapor containment, and in some applications, are used for plenum drainage, or as short-term containment of process chemicals in the event of a process vessel failure. Contact with process fluids is either dilute and intermittent, i.e., plenum drainage, or occurs as a result of process vessel splashing, filling, or wafer boat dripping and transfer. Polyolefins are advantageous because they are inexpensive polymers. However, no flame-retardant polyolefins have been able to pass the FM4910 standard. Therefore, polyolefin semiconductor chip processing equipment and clean room equipment require fire detection and suppression equipment.

[0008] Therefore, there is a need for an inexpensive flame-retardant polyolefin composition that meets the FM4910 standard. The composition should be easy to process and be able to be formed into semiconductor chip processing fixtures and clean room fixtures. The composition should have the necessary physical properties that allow it to be used to make the fixtures.

[0009] As prior art, for example, Patent Document 1 discloses a hot and cold water pipe having a cylindrical sheath pipe, a cylindrical insulating material inserted into the sheath pipe, and a cylindrical resin pipe inserted into the insulating material, the outer surface of the insulating material being wrapped with a film, wherein the difference (DC) between the inner diameter D of the sheath pipe and the outer diameter C of the insulating material is 2 to 10 mm and the outer surface of the insulating material is uneven. Patent Document 2 also discloses a method for producing a flame-retardant polyethylene resin foam by adding a blowing agent to a kneaded mixture containing a polyethylene resin and an organic flame retardant and foaming the mixture through extrusion molding, wherein the melting peak (RTm) of the polyethylene resin and the upper limit of the melting range (ATm) of the organic flame retardant satisfy the relationship 0≦RTm−ATm≦40 as determined by differential thermal analysis. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-205551 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-199760 Summary of the Invention [Problem to be solved by the invention]

[0011] In recent years, there has been an increasing demand for flame-retardant thermal insulation pipes in semiconductor manufacturing plants, and flame-retardant thermal insulation pipes are also being used for the cooling channels of various semiconductor manufacturing equipment. For example, semiconductor manufacturing equipment that requires precise operation, such as electron beam lithography equipment that forms circuit patterns on semiconductor devices, is equipped with cooling channels through which cooling water circulates to prevent operational accuracy from being reduced by drive heat. This requires insulation to maintain a constant water temperature and flame retardancy to prevent fire spread. Such equipment requires flexibility to enable narrow piping even with complex internal structures. Therefore, flexible hoses and tubes that are more flexible than the conventional metal pipes and cross-linked polyolefin resin pipes described in Patent Documents 1 and 2 are preferably used as the inner pipes of flame-retardant thermal insulation pipes.

[0012] However, when these hoses or tubes are used as inner pipes, they are bent at a much smaller bending radius than conventional flame-retardant thermal insulation pipes, which causes the foam material, particularly on the outer periphery of the bend, to stretch and thin, resulting in a loss of flame retardancy and thermal insulation.Furthermore, when the flame-retardant thermal insulation pipe is repeatedly bent and stretched, the stretched and thinned foam material does not return to its original shape, and the slack and wrinkles can rub against equipment, causing damage and generating fragments of the foam material as foreign matter.

[0013] Condensation in constant temperature and humidity clean rooms and the number of industries and work processes that dislike excess moisture is increasing. Cooling is also necessary in these cases, but condensation can occur depending on the combination of constant temperature and humidity conditions and cooling water temperature and flow rate conditions, which can result in disruption of strictly controlled constant temperature and humidity conditions, or excess moisture can react with and deactivate chemicals used in the process, often causing other problems.

[0014] In view of the above, an object of the present invention is to provide a flame-retardant and thermally insulated pipe and pipe joint that are excellent in flame retardancy and thermal insulation properties, have good flexibility, and do not allow condensed water to evaporate and scatter. [Means for solving the problem]

[0015] After extensive research, the inventors have found that the above-mentioned problems can be solved by the flame-retardant thermal insulation pipe of the present invention. The flame-retardant thermal insulation pipe of the present invention comprises a pipe body made of a flexible pipe, a foam layer made of an elastically deformable foam material laminated on the outside of the pipe body, the foam layer being a sheet-like material having a closed-cell structure obtained by chemically or physically foaming a mixture containing a thermoplastic resin and a flame retardant through extrusion molding, and a protective layer made of a protective film laminated on the outside of the foam layer, wherein the foam material has a tear strength in the extrusion direction of the extrusion molding of 15 N / cm or more and a residual elongation after 100% tension in the extrusion direction of 10% or less, as measured in accordance with JIS-K-6767, and the pipe body and the foam layer are not bonded to each other and are laminated so as to be freely movable relative to each other.

[0016] The pipe joint of the present invention is adapted to the above-mentioned flame-retardant thermally insulated pipe. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a flame-retardant and thermally insulated pipe and pipe joint that are excellent in flame retardancy and thermal insulation, have good flexibility, and do not allow condensed water to evaporate and scatter. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a partially cutaway front view of a flame-retardant thermal insulation pipe according to an embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of the present invention will now be described with reference to Fig. 1. A flame-retardant thermal insulation pipe H1 (see Fig. 1) according to an embodiment of the present invention comprises a pipe body 1 made of a flexible pipe, a foam layer 2 made of an elastically deformable foam material formed by laminating, to cover the outside of the pipe body 1, a sheet-like material having a closed-cell structure obtained by chemically or physically foaming a mixture containing a thermoplastic resin and a flame retardant through extrusion molding, and a protective layer 3 made of a thermoplastic resin film laminated to cover the outside of the foam layer 2.

[0020] The foam material constituting the foam layer 2 has a tear strength of 15 N / cm or more in the extrusion direction during extrusion molding (hereinafter referred to as the "extrusion direction") measured in accordance with JIS-K-6767, and a residual elongation of 10% or less after 100% tension in the extrusion direction. The pipe body 1 and the foam layer 2 are not bonded and are laminated so as to be able to move freely relative to each other.

[0021] By setting the tear strength (measured in accordance with JIS-K-6767) of the foam material constituting the foam layer 2 of the flame-retardant thermal insulation pipe H1 of this embodiment to 15 N / cm or more, the flame-retardant thermal insulation pipe H1 is durable enough to resist cracking or other damage even in areas where repeated stress is applied, such as the outer periphery of a bend, thereby providing a flame-retardant thermal insulation pipe H1 with long-term flame retardancy and thermal insulation properties. If the tear strength is less than 15 N / cm, cracks will form in the foam material due to repeated bending and stretching, which may result in heat conduction and melting of the internal resin in the event of a fire, making it difficult to prevent the spread of fire. This makes it impossible to achieve a flexible flame-retardant thermal insulation pipe H1. To achieve even greater durability, the tear strength is preferably 18 N / cm or more, and more preferably 20 N / cm or more.

[0022] Furthermore, by setting the residual elongation of the foam material constituting the foam layer of the flame-retardant thermal insulation pipe H1 of this embodiment after 100% tension to 10% or less, the flame-retardant thermal insulation pipe H1 has durability, preventing thickness changes and slack even in areas where repeated stress is applied, such as the outer periphery of a bend, and thus achieving flame-retardant and thermal insulation properties for a long period of time. If the residual elongation after 100% tension is greater than 10%, the foam material will not recover from thickness changes and slack caused by repeated bending and stretching, resulting in heat conduction and damage due to friction with equipment and facilities, generating foreign matter, making it impossible to achieve a flexible flame-retardant thermal insulation pipe H1. To achieve even greater durability, the residual elongation is preferably 8% or less, and more preferably 5% or less.

[0023] For the sake of convenience, foam materials for such applications are formed by extrusion molding to continuously mold a sufficient length, but it is known that foam materials obtained by extrusion molding generally have a bias in the aspect ratio of the cells, and therefore have anisotropic physical properties. The foam material that constitutes the foam layer 2 of the flame-retardant thermal insulation pipe H1 of this embodiment is laminated during molding so that the extrusion direction coincides with the axial direction of the flexible pipe, and by specifying the tear strength and residual elongation of the foam material in the extrusion direction, the above-mentioned excellent properties can be obtained.

[0024] Furthermore, the flexible pipe constituting the pipe body 1 for such applications is constructed with a material that can be stretched and compressed in the axial direction to allow for flexible bending while maintaining its flow path, making it extremely flexible and allowing it to be used with a very small bending radius. It is generally known that for the same pipe diameter, the smaller the bending radius, the greater the elongation rate on the outer periphery of the bend, and accordingly, the greater the stress applied to the foamed material laminated on the outside of the flexible pipe. By specifying the tear strength and residual elongation in the extrusion direction of the foamed material constituting the foamed layer 2, the flame-retardant thermal insulation pipe H1 of this embodiment can achieve the above-mentioned excellent properties compared to conventional flame-retardant thermal insulation pipes, even when used with a very small bending radius.

[0025] Furthermore, by laminating the pipe body 1 and the foam layer 2 of the flame-retardant thermal insulation pipe H1 of this embodiment without bonding them together and allowing them to move freely relative to each other, it is possible to prevent the foam material from being subjected to stress due to expansion and contraction of the pipe body 1, and to prevent cracks and wrinkles from occurring in the foam material due to repeated bending and stretching, thereby making it possible to provide the flame-retardant thermal insulation pipe H1 with long-term flame retardancy and thermal insulation properties.

[0026] If the pipe body 1 and foam layer 2 of the flame-retardant thermal insulation pipe H1 were bonded, repeated bending and stretching would repeatedly stretch and compress the foam together with the pipe body 1, causing cracks and wrinkles in the foam, making it impossible to achieve a flexible flame-retardant thermal insulation pipe H1. Even if the pipe body 1 and foam layer 2 of the flame-retardant thermal insulation pipe H1 were not bonded, if they were tightly attached to the pipe body with tape or heat-shrink tubing so that they could not move freely relative to each other, similar problems would occur because the foam would be subjected to stress as the pipe body stretched and compressed, making it impossible to achieve a flexible flame-retardant thermal insulation pipe H1. When connecting the end of the pipe body 1 of the flame-retardant thermal insulation pipe H1 to another device using a fitting or the like, the fact that the pipe body 1 and foam layer 2 are not bonded allows for easy removal, which is advantageous in installation work.

[0027] The clearance between the pipe body 1 and the foam layer 2 of the flame-retardant thermal insulation pipe H1 of this embodiment can be defined by the ratio (B) / (A), which is the ratio of the outer perimeter (A) of the pipe body 1 to the inner perimeter (B) of the foam layer 2. (B) / (A) is preferably in the range of 1.01 to 1.15, and more preferably 1.05 to 1.10. When the clearance is within this range, the pipe body 1 and the foam layer 2 can move freely relative to each other, there is little excess foam material that can cause slack or wrinkles, and productivity when laminating the foam layer 2 is also good.

[0028] The flexible tube constituting the tube body 1 of this embodiment is formed by extrusion molding of a mixture of either a thermoplastic resin, a thermoplastic elastomer, or a combination thereof, and various structures can be used as needed.

[0029] Examples of the structure of the flexible tube include a single-layer tube made of a single material, a multi-layer tube in which multiple layers with different physical properties are laminated, and a hose with reinforcing material between layers.

[0030] Examples of the reinforcing material include a single or multiple braid made of polyester, PET, nylon (registered trademark), or aramid fiber, etc.; a monofilament made of olefin resin, polyester resin, etc.; a multifilament made by weaving thin monofilaments (single fibers); a flat yarn (or tape yarn) made of tape-shaped thread; a metal wire made of stainless steel, etc., or a coil made of a hard material similar to stainless steel; and combinations thereof.

[0031] The foam material constituting the foam layer 2 of this embodiment is formed into a sheet shape by extruding a mixture containing a thermoplastic resin and a flame retardant and foaming it, and is laminated so as to cover the outside of the pipe body 1. Examples of the thermoplastic resin include low-molecular-weight polyolefin resin, medium- to high-molecular-weight polyolefin resin, vinyl chloride resin, urethane resin, and polyamide resin, with polyolefin resin being particularly preferred, but not limited thereto.

[0032] Examples of the thermoplastic elastomer include silicone, urethane, nitrile rubber, styrene-butadiene rubber, chloroprene, phosphazene, fluoroelastomer, perfluoroelastomer, perfluoropolyether elastomer, methylsilicone, phenylsilicone, fluorosilicone, and combinations thereof.

[0033] Examples of polyethylene resins include low-density polyethylene, linear low-density polyethylene, ethylene-vinyl acetate copolymers, ethylene-acrylate copolymers such as ethylene-methyl acrylate copolymers and ethylene-ethyl acrylate copolymers, ethylene-methacrylate copolymers such as ethylene-methyl methacrylate copolymers and ethylene-ethyl methacrylate copolymers, and combinations thereof.

[0034] Examples of the polypropylene resin include homopolypropylene, a propylene-α-olefin copolymer containing 50% by mass or more of propylene, and combinations thereof.

[0035] Polymers that pass the FM4910 standard typically have a high limiting oxygen index (LOI), exceeding 45. A typical approach to flame-retardant polyolefin materials is to add gas-phase FRs that increase the LOI. These gas-phase FRs starve the flame by sequestering the available oxygen in the area surrounding the fire. Supporting this theory, PVDF and PFA have an LOI of approximately 100, and ethylene-trifluoroethylene (ECTFE) has an LOI of approximately 60, passing the FM4910 standard. Polyvinylidene fluoride (PVDF) has an LOI of 45, which is borderline, while ethylene-trifluoroethylene (ETFE) is estimated to fail with an LOI of 38. Polypropylene and flame-retardant polypropylenes used in the past have LOIs in the range of approximately 30–35, which are also estimated to fail. As a result, resins with high LOIs or resins sufficiently compounded with flame retardants are likely to pass the FM4910 standard.

[0036] Examples of the flame retardant include halogen compounds containing bromine or chlorine, phosphorus compounds, hydrated compounds, and zinc borate. Hydrated compounds are particularly preferred because the water in the hydrated compounds evaporates, removing heat from the surface extremely quickly. This provides extremely high resistance to ignition and fire spread, and the resin forms a char layer that inhibits the spread of flames.

[0037] In addition, a flame retardant aid can be used in combination with the flame retardant to improve flame retardancy. Examples of the flame retardant aid include antimony trioxide, antimony pentoxide, zinc stannate, zinc sulfide, zinc borate, molybdenum compounds, and iron oxides. Halogen compounds are preferred as flame retardants because of their cost efficiency and excellent compatibility with polyolefin resins, and antimony trioxide and antimony pentoxide are preferred as flame retardant aids because of their large synergistic effect with halogen compounds.

[0038] Examples of methods for producing the foam include a method in which a molten resin mixed with a volatile blowing agent consisting of a linear or branched aliphatic hydrocarbon or an alicyclic hydrocarbon is extruded into a sheet or tube, and a method in which a molten resin mixed with an organic or inorganic thermally decomposable blowing agent is extruded into a sheet, followed by irradiating the extruded resin with ionizing radiation to crosslink the extruded resin, and then further heating the crosslinked sheet to foam the extruded resin.

[0039] The foam has sufficient thermal insulation properties and has an apparent density of 0.065 g / cm 3 It is preferable that the foaming ratio is 0.05 g / cm or less (approximately 15.4 times or more in terms of foaming ratio), 3 It is more preferable that the expansion ratio is not more than about 20 times.

[0040] Examples of methods for laminating the foam layer 2 in this embodiment include a method in which a foam material is extruded into a tubular shape to cover the outside of the pipe body 1 and then laminated, or a method in which a foam material that has been extruded into a sheet shape is rolled up to cover the outside of the pipe body 1, and the butted end faces are heat-sealed to form a tubular shape and then laminated.

[0041] The foam layer 2 has sufficient flame retardancy, heat insulation, and flexibility, so that the thickness of the foam layer 2 is preferably 1 to 15 mm, and more preferably 3 to 10 mm.

[0042] Examples of methods for laminating the protective layer 3 in this embodiment include a method in which a protective film made of a thermoplastic resin or a thermoplastic elastomer, etc., is wrapped around the outside of the foamed layer 2 using a T-die method or an inflation extrusion method, etc., to cover the outside of the foamed layer 2, or a method in which the protective film is formed directly on the surface of a foamed material extruded into a sheet shape using an extrusion lamination method in advance.

[0043] Furthermore, the flame-retardant thermal insulation pipe H1 of this embodiment has a Charpy impact strength of 7 kJ / m at 23°C measured in accordance with JIS-K-7111-1. 2 Charpy impact strength at 0°C measured in accordance with JIS-K-7111-1 is 5kJ / m 2The Charpy impact strength measured at -20°C according to JIS-K-7111-1 is 4kJ / m 2 It is preferable that the coating material has a flame retardancy index FPI of 6 or less and a smoke generation index SDI of 0.4 or less, as measured based on the FM4910 flame retardancy test (FMRC).

[0044] The above FM4910 flame retardancy test (FMRC) refers to the clean room materials flame retardancy test (FMRC Clean Room Materials Flammability Test) listed as Class Number 4910 of the evaluation standards established by the Factory Mutual System, an industrial mutual insurance organization based in North America.

[0045] FM4910 (Cleanroom Materials Flammability Testing Protocol) specifically evaluates materials' fire spread behavior and potential for smoke contamination, both of which are important measures for cleanroom applications, and the standard aims to "verify that the products described meet the minimum stated requirements for performance, safety, and quality." Materials are evaluated for compliance through three tests to generate a Fire Spread Index (FPI) and a Smoke Damage Index (SDI).

[0046] 1. Ignition test During the ignition test, the sample is subjected to various external heat fluxes in a fixed position and visually observed and measured for the following aspects: Time until combustion gases are generated Time to sustained ignition The results of this test are used to calculate the critical heat flux (the maximum heat flux below which ignition does not occur) and the thermal response parameter, which is an indicator of the material's resistance to ignition.

[0047] 2. Combustion test In the combustion test, the sample was heated to 50 kW / m 2 After exposure to an external heat flux of 1000 kJ / s, the following items are measured: Time to evaporation - Confirmation of sustained ignition Flame height Heat, CO, CO2, hydrocarbon, and smoke release rates This derived smoke volume value is used to calculate the Smoke Harm Index (SDI), which indicates the degree of smoke contamination of the environment during fire propagation.

[0048] 3. Fire propagation test To simulate a large-scale fire outbreak, the fire spread test is carried out in a chamber with 40% oxygen. The bottom of the sample is exposed to a 50 kW / m flame in the presence of a pilot flame. 2 Once the sample begins to burn, the test is continued until no visible flames are visible and no vapors of the substance are produced from any surface of the sample.

[0049] The purpose of this test is to determine whether the fire will spread naturally from the heat flux of its own flame, and the result is classified between "no fire spread" and "accelerated fire spread." The test ultimately determines the Fire Spread Index (FPI), which is an index that indicates the tendency of a material to accelerate the spread of fire.

[0050] The flame-retardant thermal insulation pipe H1 in this embodiment can be made of a thermoplastic resin or a thermoplastic elastomer. Although there is no particular specification for the material, examples include soft vinyl chloride, polyolefin, fluorine-based resin, urethane resin, and polyolefin-based thermoplastic elastomer.

[0051] The flame-retardant thermal insulation pipe H1 of this embodiment can be used as piping for various chemical raw materials, chemicals, air, various gases, water, etc. in the fields of food, beverage, semiconductor manufacturing, medical equipment, chemistry, and other industries. It is particularly suitable as a hose for cooling water.

[0052] The present invention can also be applied to a pipe joint adapted to the flame-retardant thermally insulated pipe H1 according to this embodiment.

[0053] The flame-retardant thermal insulated pipe H1 according to the present embodiment described above can provide the following effects: Compared to conventional flame-retardant thermal insulated pipes, the flame-retardant thermal insulated pipe H1 according to the present embodiment is flexible, has excellent flame retardancy, and heat insulating properties, and can be used for a long period of time without losing its flame retardancy and heat insulating properties because the foamed layer 2 is not damaged, even when used with an extremely small bending radius or when repeatedly bent and stretched. This gives it a much longer life than conventional products.

[0054] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the present invention. [Explanation of symbols]

[0055] 1 pipe body 2 foam layer 3 Protective layer H1 Flame-retardant thermal insulation pipe

Claims

1. a tube body made of a flexible tube; a foam layer made of an elastically deformable foam material, the foam layer being formed by laminating a sheet-like material having a closed-cell structure obtained by chemically or physically foaming a mixture containing a thermoplastic resin and a flame retardant through extrusion molding so as to cover the outside of the pipe body; a protective layer made of a protective film laminated so as to cover the outside of the foam layer, The foam material has a tear strength of 15 N / cm or more in the extrusion direction of the extrusion molding measured in accordance with JIS-K-6767, and a residual elongation rate of 10% or less after 100% tension in the extrusion direction, A flame-retardant thermally insulated pipe, characterized in that the pipe body and the foam layer are not bonded to each other and are laminated so as to be able to move freely relative to each other.

2. 2. The flame-retardant thermally insulated pipe according to claim 1, wherein a ratio (B) / (A) of an outer perimeter (A) of the pipe body to an inner perimeter (B) of the foamed layer satisfies a range of 1.05 to 1.

1.

3. 3. The flame-retardant thermally insulated pipe according to claim 2, wherein the pipe body made of a flexible pipe is a pliable flexible pipe formed by extrusion molding of a mixture made of either a thermoplastic resin, a thermoplastic elastomer, or a combination thereof.

4. Charpy impact strength at 23°C measured according to JIS-K-7111-1 is 7 kJ / m ２ The Charpy impact strength at 0°C measured in accordance with JIS-K-7111-1 is 5 kJ / m ２ The Charpy impact strength at -20°C measured in accordance with JIS-K-7111-1 is 4 kJ / m ２ 4. The flame-retardant thermal insulation pipe according to claim 3, wherein the coating material has a flame retardancy index FPI of 6 or less and a smoke generation index SDI of 0.4 or less, as measured in accordance with the flame retardancy test (FMRC) of FM4910.

5. 5. The flame-retardant thermal insulation pipe according to claim 3, which is used for cooling water.

6. A pipe joint adapted for the flame-retardant thermally insulated pipe according to claim 5.

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