JP7765337B2 - Joints, piping structures - Google Patents

Description

The present invention relates to a joint.

A joint described in Patent Document 1 below has been known. This joint comprises a joint body and a sound-insulating cover. The sound-insulating cover is wrapped around the joint body. A space (air layer) is provided between the joint body and the sound-insulating cover.

Japanese Patent Application Laid-Open No. 2019-178592

When the above-mentioned joint is heated for any reason, there is a risk that the sound-insulating cover may warp. If the sound-insulating cover is secured to the joint body with tape, warping of the sound-insulating cover may cause the tape to peel off. In this case, a gap may form between the joint body and the sound-insulating cover, which may affect fire resistance.

The present invention was made in consideration of the above-mentioned circumstances, and aims to reduce the occurrence of deflection in sound-insulating covers.

<1> A fitting according to one aspect of the present invention comprises a fitting body and a sound-insulating cover made of an olefin resin that covers the fitting body from the radial outside of the fitting body, wherein a space is provided between the fitting body and the sound-insulating cover, the sound-insulating cover is long and wrapped around the fitting body, the longitudinal direction of the sound-insulating cover is the circumferential direction of the fitting body, the lateral direction of the sound-insulating cover is the axial direction of the fitting body, and the linear expansion coefficient of the sound-insulating cover in the lateral direction is smaller than the linear expansion coefficient of the sound-insulating cover in the longitudinal direction.

The linear expansion coefficient of the sound-insulating cover in the short direction is smaller than the linear expansion coefficient of the sound-insulating cover in the long direction. Therefore, the sound-insulating cover is less likely to expand in the axial direction. This makes it possible to suppress deflection of the sound-insulating cover.

<2> In the joint according to the above item <1>, a configuration may be adopted in which the linear expansion coefficient of the sound-insulating cover in the short-side direction is 800×10 ⁻⁶ (1/° C.) or less.

The linear expansion coefficient of the sound-insulating cover in the short-side direction is 800×10 ⁻⁶ (1/° C.) or less, which makes it possible to reliably suppress deflection of the sound-insulating cover.

<3> In the joint according to <1> or <2> above, the longitudinal direction of the sound-insulating cover may be configured to be the same as the extrusion direction of the original sheet of the sound-insulating cover.

Generally, the linear expansion coefficient of the original sheet of the sound-insulating cover increases in the extrusion direction, whereas the linear expansion coefficient of the original sheet of the sound-insulating cover decreases in the direction perpendicular to the extrusion direction.
The longitudinal direction of the sound insulating cover is the extrusion direction of the original sound insulating cover. Therefore, the lateral direction of the sound insulating cover is perpendicular to the extrusion direction of the original sound insulating cover. This reliably reduces the linear expansion coefficient of the sound insulating cover in the lateral direction.

<4> In a fitting according to any one of the above aspects <1> to <3>, the fitting body may include a main pipe extending in the axial direction and two sockets disposed at both ends of the main pipe in the axial direction, the outer diameter of the main pipe being smaller than the outer diameters of the two sockets, both ends of the sound-insulating cover in the axial direction being fixed to the two sockets, and the space being provided between the main pipe and the sound-insulating cover.

This invention makes it possible to reduce the occurrence of deflection in the sound-insulating cover.

FIG. 1 is a cross-sectional view showing a joint according to an embodiment of the present invention, illustrating a side view of a joint body. 2 is a cross-sectional view corresponding to the cross-sectional view taken along the line II-II in FIG. 1. FIG. 2 is a development view of a sound insulating cover that constitutes the joint shown in FIG. 1 . FIG. 2 is a perspective view of an original sheet of a sound-insulating cover that constitutes the joint shown in FIG. 1 . FIG. 10 is a development view of a sound-insulating cover constituting a joint of a comparative example in a verification test. FIG. 1 is a diagram illustrating a test method for the fire resistance of a joint in a verification test. FIG. 2 is a diagram showing an example of the state of a joint of an example after a fire resistance test in a verification test, and corresponds to the cross-sectional view shown in FIG. 1 . FIG. 2 is a diagram showing an example of the state of a joint of a comparative example after a fire resistance test in a verification test, and corresponds to the cross-sectional view shown in FIG. 1 .

Hereinafter, a piping structure 10 according to one embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG.
As shown in FIG. 1 , the piping structure 10 is provided in a building 1. The piping structure 10 penetrates a slab 2 (e.g., a floor slab) of the building 1 in the vertical direction Z. The slab 2 divides the building 1 into floors. The piping structure 10 may have fire resistance. The piping structure 10 may be, for example, a drainage pipe, a water supply pipe, or a ventilation pipe. The piping structure 10 includes a joint 20 (pipe joint) and a pipe 30. The joint 20 may be a fire-resistant joint, and the pipe 30 may be a fire-resistant pipe.

(Joint 20)
Examples of the fitting 20 include a so-called socket, a tee, and a manifold fitting. As shown in FIGS. 1 and 2 , the fitting 20 includes a fitting body 21 and a sound-insulating cover 22. The fitting body 21 includes a main pipe 23 and a socket 24. The axis O of the main pipe 23 is along the vertical direction Z. The sockets 24 are located at both ends of the main pipe 23 in the vertical direction Z. The fitting body 21 includes one socket 24 at each of the upper and lower ends of the main pipe 23. The fitting body 21 includes two sockets 24. The two sockets 24 are located coaxially (on the axis O). The outer diameter of the main pipe 23 is smaller than the outer diameters of the two sockets 24. The fitting body 21 may further include one or more branch pipes (not shown). The branch pipes extend radially (horizontally) from the main pipe 23.

(Joint body 21)
The joint body 21 is made of resin (e.g., rigid polyvinyl chloride resin, which is a polyvinyl chloride-based resin containing no plasticizer) and has a shape and dimensions conforming to the nominal diameter of 30 to 150 for DV joints specified in JIS K 6739, although larger nominal diameters are also acceptable. In particular, the high rigidity of the sound-insulating cover 22 in the present invention reduces the use of spacers, which are detrimental to fire resistance. This is particularly effective for joints with medium diameters (nominal diameter 65 or more (socket inner diameter 76 mm or more) and nominal diameter 125 or less (socket inner diameter 140 mm or less)) in which the slab penetration hole is large and detrimental to fire resistance. The effect is particularly significant for joints with large diameters (nominal diameter 150 or more (socket inner diameter 165 mm or more) and nominal diameter 300 or less (socket inner diameter 318 mm or less)). The joint body 21 is produced by injection molding the resin composition (A).

[Resin composition (A)]
Examples of the polyvinyl chloride resin contained in the resin composition (A) include polyvinyl chloride homopolymers, copolymers of vinyl chloride monomers with other monomers having unsaturated bonds copolymerizable with the vinyl chloride monomers, graft copolymers in which vinyl chloride monomers are graft copolymerized onto polymers other than polyvinyl chloride resins, etc. The polyvinyl chloride resins may be used alone or in combination of two or more.
The polyvinyl chloride resin may be further chlorinated. Examples of methods for chlorinating polyvinyl chloride resin include thermal chlorination and photochlorination.

Examples of other monomers having an unsaturated bond copolymerizable with the vinyl chloride monomer include α-olefins such as ethylene, propylene, and butylene; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as butyl vinyl ether and cetyl vinyl ether; (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, and butyl acrylate; aromatic vinyls such as styrene and α-methylstyrene; and N-substituted maleimides such as N-phenylmaleimide and N-cyclohexylmaleimide. One of the other monomers may be used alone, or two or more may be used in combination.

Examples of polymers that can be graft-copolymerized with the vinyl chloride monomer include ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-carbon monoxide copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate-carbon monoxide copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, acrylonitrile-butadiene copolymer, polyurethane, chlorinated polyethylene, and chlorinated polypropylene. These polymers may be used alone or in combination of two or more.

The polyvinyl chloride resin may be crosslinked. Examples of methods for crosslinking polyvinyl chloride resins include adding a crosslinking agent and peroxide, irradiating with electron beams, and using a water-crosslinkable material.

The average degree of polymerization of the polyvinyl chloride resin is preferably 400 or more and 1000 or less, and more preferably 600 or more and 900 or less. Here, the average degree of polymerization is the average degree of polymerization measured in accordance with JIS K-6721 "Testing methods for vinyl chloride resins" using a resin sample obtained by dissolving the polyvinyl chloride resin in tetrahydrofuran (THF), removing insoluble components by filtration, and then drying and removing the THF in the filtrate.
When the average degree of polymerization of the polyvinyl chloride resin is equal to or greater than the lower limit, the mechanical strength can be sufficiently increased, and when it is equal to or less than the upper limit, sufficient moldability can be ensured.

The resin composition (A) may contain an endothermic agent. The endothermic agent is a compound that has an endothermic effect and suppresses temperature rise when heated by a fire, etc. For example, a compound that undergoes an endothermic reaction such as a dehydration reaction when heated can be used as the endothermic agent.
Examples of compounds that undergo a dehydration reaction when heated include inorganic hydroxides such as magnesium hydroxide, aluminum hydroxide, kaolin minerals (kaolinite, halloysite, dickite) and hydrotalsalcite, and inorganic compounds with water absorption properties such as sepiolite, bentonite, montmorillonite, talc, mica, quartz, zeolite, wollastonite, and nepheline syenite. Hereinafter, inorganic hydroxides and inorganic compounds that undergo a dehydration reaction when heated will be collectively referred to as "thermally dehydrated compounds." In thermally dehydrated compounds, the temperature rise can also be suppressed by the latent heat of vaporization of water generated by the dehydration reaction.
Among the thermally dehydrated compounds, magnesium hydroxide undergoes a dehydration reaction at temperatures of 300°C or higher. Therefore, when magnesium hydroxide is used as the endothermic agent, the occurrence of a dehydration reaction can be suppressed when the resin composition (A) is molded to produce the joint body 21.
Among the thermally dehydrated compounds, aluminum hydroxide undergoes a dehydration reaction at about 200°C, so when aluminum hydroxide is used as the heat-absorbing agent, it can quickly absorb the heat transferred to the fitting body 21 in the event of a fire. This makes it possible to further prevent the fitting body 21 from deforming and losing its fire resistance before the pipe 30 thermally expands.

Among the thermally dehydrated compounds, hydrotalcite has the chemical name magnesium aluminum hydroxide carbonate hydrate, and is a type of mineral represented by Mg ₆ Al ₂ (OH) _{16 CO} 3.4H ₂ O, etc. It is a layered inorganic compound consisting of a positively charged basic layer [Mg _1-x Al _x (OH) ₂ ] ^x+ and a negatively charged intermediate layer [(CO ₃ ) _x/ 2.mH ₂ O] ^x- . Many divalent and trivalent metals have a similar layered structure, and these are represented by the following general formula:
[M ²⁺ _1-x M ³⁺ _x (OH) ₂ ] ^x+ [A ^n- _x/n・mH ₂ O] ^x-
M ²⁺ : divalent metal ion such as Mg ²⁺ or Zn ²⁺ M ³⁺ : trivalent metal ion such as Al ³⁺ or Fe ³⁺ A ^n- : n-valent anion such as CO ₃ ^2- , Cl ^- or NO ₃ ^- X: 0<X≦0.33
In hydrotalcite, the water of crystallization present between molecules begins to dehydrate at approximately 180°C, and the water of crystallization is completely eliminated at approximately 300°C. Up to this state, synthetic hydrotalcite maintains its crystalline structure, but above approximately 350°C, the crystalline structure begins to collapse, releasing water and carbon dioxide. Furthermore, synthetic hydrotalcite begins its endothermic decomposition at a temperature that is 60°C to 75°C lower than the thermal decomposition temperature of vinyl chloride resin, which is approximately 200°C to 300°C. Therefore, the endothermic decomposition of vinyl chloride resin can be efficiently suppressed by the endothermic decomposition of hydrotalcite.
The endothermic agent may be a combination of at least two of magnesium hydroxide, aluminum hydroxide, kaolin-based minerals, and hydrotalcite.

The heat-dehydrated compound is usually in the form of particles.
The volume average particle diameter of the thermally dehydrated compound is preferably 0.01 μm or more and 20 μm or less, more preferably 0.05 μm or more and 2 μm or less, and even more preferably 0.05 μm or more and 1 μm or less. By setting the volume average particle diameter of the thermally dehydrated compound within this range, it is possible to impart transparency to the joint body 21 and improve the dispersibility of the thermally dehydrated compound. The volume average particle diameter is a value measured using a laser diffraction/scattering particle size distribution measuring device.
The BET specific surface area of the thermally dehydrated compound is preferably 1 m ² /g or more and 40 m ² /g or less, and more preferably 1 m ² /g or more and 20 m ² /g or less. Here, the BET specific surface area is a value determined using nitrogen adsorption.
When the volume average particle diameter and BET specific surface area of the thermally dehydrated compound are within the above ranges, the compound can fully exert its effect as a heat-absorbing agent, and the moldability of the resin composition (A) when producing the joint body 21 and the mechanical properties of the joint body 21 can be fully ensured.

The particle surface of the thermally dehydrated compound is preferably treated with a surface treatment agent such as a higher fatty acid such as stearic acid or a silane coupling agent. The thermally dehydrated compound treated with a surface treatment agent has high dispersibility in polyvinyl chloride resins and is more likely to exhibit its endothermic effect. Furthermore, when the thermally dehydrated compound is basic, it can make the polyvinyl chloride resin less susceptible to discoloration and prevent yellowing.
When the thermally dehydratable compound is surface-treated with a surface treatment agent, the amount of the surface treatment agent is preferably 0.05 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of the thermally dehydratable compound. When the amount of the surface treatment agent is equal to or more than the lower limit, the dispersibility of the thermally dehydratable compound in the polyvinyl chloride resin can be sufficiently increased, and when the amount is equal to or less than the upper limit, a decrease in economic efficiency can be suppressed.

The content of the endothermic agent in resin composition (A) is preferably 0.01 to 10.0 parts by mass, more preferably 0.05 to 5.0 parts by mass, and even more preferably 0.1 to 2.0 parts by mass, per 100 parts by mass of polyvinyl chloride resin. If the content of the endothermic agent in resin composition (A) is equal to or greater than the lower limit, deformation of the joint body 21 in the event of a fire can be further suppressed. If the content is equal to or less than the upper limit, moldability when producing the joint body 21 can be sufficiently improved, and the mechanical properties of the joint body 21 can be improved.

The resin composition (A) may contain a flame retardant other than the heat-absorbing agent as long as the effects of the present invention are not impaired.
Examples of other flame retardants include antimony oxides such as hydrotalcite, antimony dioxide, antimony trioxide, and antimony pentoxide; molybdenum compounds such as molybdenum trioxide, molybdenum disulfide, and ammonium molybdate; bromine-based compounds such as tetrabromobisphenol A, tetrabromoethane, and tetrabromoethane; phosphorus-based compounds such as triphenyl phosphate and ammonium polyphosphate; and boric acid-based compounds such as calcium borate and zinc borate. Among the other flame retardants, antimony trioxide is preferred because of its high effect of inhibiting the combustion of polyvinyl chloride.

Furthermore, the resin composition (A) may contain additives such as lubricants, processing aids, impact modifiers, heat resistance improvers, antioxidants, heat stabilizers, heat stabilization aids, light stabilizers, ultraviolet absorbers, pigments, plasticizers, and thermoplastic elastomers, as long as the effects of the present invention are not impaired.
The additives described below may be used alone or in combination of two or more.

Examples of the heat stabilizer include lead-based stabilizers, tin-based stabilizers, Ca—Zn-based stabilizers, higher fatty acid metal salts, etc. One type of heat stabilizer may be used alone, or two or more types may be used in combination.
Examples of lead-based stabilizers include white lead, basic lead sulfite, tribasic lead sulfate, dibasic lead phosphite, dibasic lead phthalate, tribasic lead maleate, silica gel coprecipitated lead silicate, dibasic lead stearate, lead stearate, and lead naphthenate.
Examples of tin-based stabilizers include mercaptides such as dibutyltin mercapto, dioctyltin mercapto, and dimethyltin mercapto; malates such as dibutyltin maleate, dibutyltin maleate polymer, dioctyltin maleate, and dioctyltin maleate polymer; and carboxylates such as dibutyltin mercaptodibutyltin laurate and dibutyltin laurate polymer.
The Ca-Zn stabilizer is a mixture of a fatty acid salt of calcium and a fatty acid salt of zinc. Examples of the fatty acid include behenic acid, stearic acid, lauric acid, oleic acid, palmitic acid, ricinoleic acid, and benzoic acid, and two or more of these may be used in combination.
Examples of higher fatty acid metal salts include lithium stearate, magnesium stearate, calcium stearate, calcium laurate, calcium ricinoleate, strontium stearate, barium stearate, barium laurate, barium ricinoleate, cadmium stearate, cadmium laurate, cadmium ricinoleate, cadmium naphthenate, cadmium 2-ethylhexoate, zinc stearate, zinc laurate, zinc ricinoleate, zinc 2-ethylhexoate, lead stearate, dibasic lead stearate, and lead naphthenate.
Among these, when the joint body 21 is to be made transparent, a tin-based stabilizer or a Ca-Zn-based stabilizer is preferred, and as tin-based stabilizers, those that do not contain sulfur, such as malates and carboxylates, are particularly preferred in order to prevent sulfide contamination, and as Ca-Zn-based stabilizers, stearates are particularly preferred in terms of the balance between lubricity and plate-out during molding processing.

The content of the heat stabilizer is preferably 0.3 to 5.0 parts by mass per 100 parts by mass of the polyvinyl chloride resin. If the content of the heat stabilizer is above the lower limit, the thermal stability of the polyvinyl chloride resin during molding can be improved. If the content is below the lower limit, the polyvinyl chloride resin can be sufficiently carbonized during combustion, resulting in sufficient fire resistance.

Examples of the heat stabilization aid include epoxidized soybean oil, phosphate ester, polyol, hydrotalcite, and zeolite.
Examples of the light stabilizer include hindered amine light stabilizers.
Examples of the ultraviolet absorber include salicylic acid ester-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers.

Examples of pigments include organic pigments such as azo pigments, phthalocyanine pigments, threne pigments, and dye lakes; and inorganic pigments such as oxide pigments, molybdenum chromate pigments, sulfide/selenide pigments, and ferrocyanide pigments.

(Sound-insulating cover 22)
The sound-insulating cover 22 covers the joint body 21 from the radial outside of the joint body 21. As shown in FIGS. 1 to 3 , the sound-insulating cover 22 is long and wrapped around the joint body 21. The longitudinal direction A of the sound-insulating cover 22 is the circumferential direction of the joint body 21. The short-side direction B of the sound-insulating cover 22 is the axial direction (vertical direction Z) of the joint body 21. Both ends of the sound-insulating cover 22 in the longitudinal direction A are fixed by fixing members (not shown). The ends of the sound-insulating cover 22 in the longitudinal direction A may overlap, but because the heat storage capacity of the joint 20 at the overlapping portions is higher than at other portions, making the joint body 21 more susceptible to deformation, it is preferable that the end faces of the sound-insulating cover 22 in the longitudinal direction A face each other. Examples of the fixing member include hook-and-loop fasteners, adhesives, and tapes. If the joint body 21 is provided with a branch pipe, an opening into which the branch pipe is inserted may be provided in a portion of the sound-insulating cover 22 that corresponds to the branch pipe. Here, Fig. 2 does not illustrate a state in which both ends of the sound-insulating cover 22 in the longitudinal direction A are fixed by fixing members.

The sound-insulating cover 22 is made of resin. In this embodiment, the sound-insulating cover 22 is formed into a sheet from an elastic material such as modified asphalt, elastomer, rubber, polyolefin resin, or soft vinyl chloride resin. Polyolefin resins that do not contain plasticizers are preferred due to their high bending resistance. The bending resistance can be further increased by using a resin composition (A) that contains 300 to 600 parts by weight of inorganic filler per 100 parts by weight of polyolefin resin.

The polyolefin resin is not particularly limited, but examples thereof include low-density polyethylene, high-density polyethylene, linear low-density polyethylene, atactic polypropylene, isotactic polypropylene, syndiotactic polypropylene, and poly-α-olefin. Among these, polyethylene having a density of 0.87 to 0.93 g/cm ³ is preferred as the polyolefin resin. If the density is less than 0.87 g/cm ³ , the strength of the sound-insulating cover 22 is insufficient. If the density exceeds 0.93 g/cm ³ , the sound-insulating cover 22 may buckle when flattened (when an axial force is applied to the tubular body 31). Furthermore, if the flexural modulus of the olefin resin is 100 to 3000 kg/cm ² , the strength and winding processability are sufficient.
The sound-insulating cover 22 may contain a material other than the polyolefin resin, such as polyvinyl chloride resin, polystyrene resin, ABS resin, AS resin, elastomer material, etc. Furthermore, even if the material is different from the polyolefin resin, such as modified asphalt, elastomer, rubber, soft polyvinyl chloride resin, etc., which has a lower bending resistance than the polyolefin resin, it is sufficient if the material has a certain thickness or is layered with an inorganic filler or a fiber sheet such as a nonwoven fabric to provide a predetermined bending resistance.

The inorganic filler is not particularly limited, but examples include silica, diatomaceous earth, alumina, zinc oxide, titanium oxide, calcium oxide, magnesium oxide, iron oxide, tin oxide, antimony oxide, ferrites, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, basic magnesium carbonate, calcium carbonate, magnesium carbonate, zinc carbonate, barium carbonate, dawnnite, hydrotalcite, calcium sulfate, barium sulfate, gypsum fiber, calcium silicate, talc, clay, mica, montmorillonite, bentonite, activated clay, sepiolite, imogolite, sericite, glass fiber, glass beads, silica-based balun, aluminum nitride, boron nitride, silicon nitride, carbon black, graphite, carbon fiber, carbon balun, charcoal powder, various metal powders, potassium titanate, magnesium sulfate, lead zirconate titanate, aluminum borate, molybdenum sulfide, silicon carbide, stainless steel fiber, zinc borate, various magnetic powders, slag fiber, fly ash, and dewatered sludge. Of these, calcium carbonate is preferably used as the inorganic filler from the perspective of balancing weight and cost. These may be used alone or in combination of two or more.

The sound-insulating cover 22 is cut out, for example, from a raw roll 50 of the sound-insulating cover 22 as shown in FIG. 4. The raw roll 50 is manufactured by winding up a sheet formed by extrusion molding, for example, an olefin resin that does not contain a plasticizer. As shown in FIG. 3, the longitudinal direction A of the sound-insulating cover 22 may be the extrusion direction MD of the raw roll 50, or may be a direction perpendicular to the extrusion (hereinafter simply referred to as the orthogonal direction TD). The short-side direction B of the sound-insulating cover 22 may be the extrusion direction MD or the orthogonal direction TD. In this embodiment, the longitudinal direction A of the sound-insulating cover 22 is the extrusion direction MD, and the short-side direction B of the sound-insulating cover 22 is the orthogonal direction TD.

Generally, the linear expansion coefficient of this type of raw web 50 is large in the extrusion direction MD, while the linear expansion coefficient is small in the orthogonal direction TD of the raw web 50 .
In this embodiment, the linear expansion coefficient of the sound-insulating cover 22 in the widthwise direction B is smaller than the linear expansion coefficient of the sound-insulating cover 22 in the lengthwise direction A. The linear expansion coefficient of the sound-insulating cover 22 in the widthwise direction B is 800×10 ⁻⁶ (1/°C) or less.
The linear expansion coefficient of the sound insulating cover 22 is measured as follows.
The sound-insulating cover 22 is cut into a square with sides parallel to the TD and MD directions, and the lengths L _TD and L _MD of each are measured. Next, the lengths L _TD1 [cm] and L _MD1 [cm] in the TD and MD directions at 15°C are measured to 10 decimal places using a microscope. Next, the lengths L _TD2 [cm] and L _MD2 [cm] in the TD and MD directions at 25°C are measured to 5 decimal places using a microscope. From the obtained L2 and L1, the linear expansion coefficient in the TD direction is calculated using equation (1): α _TD = (L _TD2 - _{L TD1} ) / L _TD × (1/10 [°C]), and the linear expansion coefficient in the MD direction is calculated using equation (2): α _MD = (L _MD2 - _{L MD1} ) / L _MD × (1/10 [°C]).

As shown in FIG. 1, the upper and lower ends of the sound-insulating cover 22 are fixed to the two sockets 24, respectively. The sound-insulating cover 22 is fixed to the fitting body 21 with tape 25. The tape 25 is provided around the entire circumference. The material of the tape 25 is not particularly limited, but examples include resin tapes such as soft polyvinyl chloride resin, rubber-based resin, olefin-based resin, and acrylic-based resin; fiber tapes such as paper and cloth; and metal tapes such as aluminum, with an adhesive layer attached to the base tape. In particular, resin tapes such as olefin-based resin and acrylic resin that do not contain plasticizers, paper or cloth tapes, and aluminum tapes are preferred. The adhesive layer is not particularly limited, but examples include rubber-based adhesives and acrylic adhesives.

1 and 2 , a space S is provided between the joint body 21 and the sound-insulating cover 22. The space S is provided between the main pipe 23 and the sound-insulating cover 22. At least a portion of the space S in the up-down direction Z (axial direction) is continuous in the circumferential direction of the joint body 21. If the joint body 21 does not include a branch pipe, the space S may be continuous in the circumferential direction over the entire area in the up-down direction Z between the main pipe 23 and the sound-insulating cover 22. If the joint body 21 includes a branch pipe, the space S may be continuous in the circumferential direction at a position between the main pipe 23 and the sound-insulating cover 22 that avoids the branch pipe in the up-down direction Z (above or below the branch pipe).
A fire-resistant and heat-resistant fiber sheet such as rock wool or glass wool may be placed in the space S. By placing these fire-resistant and heat-resistant sheets throughout the space S, the joint body 21 will not be heated locally, and deformation of the joint body 21 can be suppressed even without providing the space S.

The fitting 20 may also include a spacer. An example of a spacer is a foam tape made of closed-cell polyethylene foam. The spacer is disposed, for example, on the outer surface of the main pipe 23. If the fitting body 21 includes a spacer, it is preferable that the spacer be provided in a position that avoids the lower end of the main pipe 23. In this case, the spacer prevents the lower end of the main pipe 23 from overheating. It is also preferable that the spacer be longer in the circumferential direction than in the vertical direction Z. In this case, the spacer makes it less likely that the spacer will divide the space S between the main pipe 23 and the sound-insulating cover 22 in the circumferential direction.

In the joint 20, at least the socket 24 of the joint body 21 located below the main pipe 23 (hereinafter simply referred to as the lower socket 24) is embedded in the slab 2. In this embodiment, the entire lower socket 24 is embedded in the slab 2. The lower end of the lower socket 24 is located at a position equivalent to the lower surface of the slab 2 in the vertical direction Z, or higher than the lower surface of the slab 2. The upper end of the lower socket 24 is located at a position equivalent to the upper surface of the slab 2 in the vertical direction Z, or lower than the upper surface of the slab 2. However, the lower surface of the slab 2 may be located below the lower socket 24, or the upper surface of the slab 2 may be located above the lower socket 24. The joint 20 is disposed in a compartment penetration 2a (through hole) that penetrates the slab 2, and mortar 3 is filled between the joint 20 and the slab 2.

(tube 30)
The pipe 30 is connected to the fitting 20. The pipe 30 includes a first vertical pipe 31 and a second vertical pipe 32. The first vertical pipe 31 is located above the fitting 20 and is connected to the upper socket 24. The second vertical pipe 32 is located below the fitting 20 and is connected to the lower socket 24. When the fitting 20 includes a branch pipe, the pipe 30 may also include a horizontal pipe. The horizontal pipe is connected to the branch pipe. Note that the first vertical pipe 31 may not be connected to the upper socket 24, and the upper socket 24 may be closed with a cover (not shown). When the fitting 20 includes a branch pipe, the branch pipe may be closed with a cover (not shown). When the fitting 20 includes multiple branch pipes, some of the branch pipes may be closed with covers (not shown), and the remaining parts may be connected to horizontal pipes.

Of the tubes 30, at least the first vertical tube 31 and the second vertical tube 32 are preferably made of a resin composition containing thermally expandable graphite. The tube 30 contains a resin composition (B) containing a thermoplastic resin and thermally expandable graphite. That is, the tube 30 is produced by molding the resin composition (B) and contains a thermoplastic resin and thermally expandable graphite. Typically, the tube 30 is produced by extrusion molding the resin composition (B).
The pipe 30 may have a single-layer structure in which the entire pipe 30 is made of the resin composition (B), or a multi-layer structure made of multiple layers. That is, the pipe 30 has a tubular peripheral wall with a single-layer structure or a multi-layer structure.
When the pipe 30 has a multi-layer structure, any one of the layers may be formed from the resin composition (B). For example, when the pipe 30 has a three-layer structure consisting of a surface layer, an intermediate layer, and an inner layer, the intermediate layer may be formed from the resin composition (B), and the surface layer, intermediate layer, and inner layer may contain a flame retardant. The surface layer is located on the outer peripheral surface of the tubular intermediate layer, and the inner layer is located on the inner peripheral surface of the intermediate layer.
The intermediate layer is black because it contains thermally expandable graphite, so it is preferable that the surface layer and the inner layer contain a colorant other than black so that they can be distinguished from the intermediate layer.
In this embodiment, the intermediate layer is a fire-resistant layer. In addition, in this embodiment, the surface layer and the inner layer are coating layers, and the inner layer is an inner coating layer.

The size of the pipe 30 is, for example, a nominal diameter of 40 (outer diameter 48 mm) or more and a nominal diameter of 300 (outer diameter 318 mm) or less.
The SDR (outer diameter/thickness (wall thickness) of the tube 30) is, for example, preferably 13 to 35, more preferably 15 to 33, and even more preferably 17 to 30. If the SDR is equal to or greater than the lower limit, the thermally expandable graphite is more likely to be oriented in the circumferential direction of the tube 30, thereby increasing the compressive strength and decreasing the thermal conductivity. If the SDR is equal to or less than the upper limit, the wall thickness does not become too thin, and the compressive strength and fire resistance can be increased.

In the case of a multi-layer structure, the intermediate layer may be a foamed layer or a non-foamed layer. By using a foamed layer as the intermediate layer, the thermal conductivity can be further reduced.
For example, in the case of a nominal diameter of 100A (outer diameter 114mm), the thickness of the intermediate layer is preferably 1.8mm to 7.6mm, more preferably 2.0mm to 6.0mm, and even more preferably 2.5mm to 5.0mm. The thickness of the intermediate layer is preferably 85% or less of the thickness of the pipe 30, more preferably 70% or less, and even more preferably 60% or less. If the thickness of the intermediate layer is within the above range, the fire resistance and compressive strength can be further increased.

In the case of a multi-layer structure, the surface layer and the inner layer may be foamed layers or non-foamed layers. By using non-foamed layers as the surface layer and the inner layer, the strength of the pipe 30 can be further increased.
For example, in the case of a nominal diameter of 100A (outer diameter 114mm), the thickness of the surface layer and the inner layer is preferably 0.3 mm to 3.0 mm, and more preferably 0.6 mm to 1.5 mm. If the thickness of the coating layer is 0.3 mm or more, the mechanical strength of the pipe 30 can be sufficiently ensured, and if it is 3.0 mm or less, a decrease in fire resistance can be suppressed.

The compression ratio of the tube 30 is preferably 20% or more, more preferably 30% or more, even more preferably 40% or more, and particularly preferably 50% or more. If the compression ratio is equal to or greater than the above-mentioned lower limit, the tube 30 is less likely to break even when subjected to crushing forces during transportation or piping. In addition, the thermally expandable graphite is oriented in the circumferential direction of the tube 30, thereby reducing thermal conductivity. The upper limit of the compression ratio of the tube 30 is substantially 90% or less.
The compressibility of the tube 30 is measured by the flattening test of JIS K 6741:2007. A ring-shaped test piece of 50 mm or more is cut from the tube 30 and left at 23°C for one hour. The test piece is then sandwiched between two flat plates and the outer diameter of the tube 30 is compressed in a direction perpendicular to the axis of the tube 30 at a speed of 10 mm/min. The degree of radial compression at the time of fracture of three ring-shaped test pieces is measured, and the average value is taken as the compressibility. For example, if the tube 30 fractures when its outer diameter is reduced to two-thirds, this means that one-third of the outer diameter has been compressed, i.e., 33% of the outer diameter has been compressed, and the compressibility is 33%.
The compression ratio of the tube 30 can be adjusted by combining compositional aspects such as the amount and aspect ratio of thermally expandable graphite and the type of flame retardant, with structural aspects such as the SDR of the tube 30, the location of the weld line, the layer structure of the tube 30, and the thickness of each layer.

The thermal conductivity of the tube 30 is preferably 0.3 W/m·K or less, more preferably 0.28 W/m·K or less, and even more preferably 0.25 W/m·K or less. If the thermal conductivity is equal to or less than the upper limit, the tube 30 is less likely to form condensation.
The thermal conductivity of the tube 30 is a value measured in the thickness direction at three locations on the tube 30 at 23° C. in accordance with JIS A1412-2:1999.
The thermal resistance value (value obtained by dividing the thickness by the thermal conductivity) of the tube 30 is preferably 0.03 m ² K/W or more, and more preferably 0.04 m ² K/W or more.

[Resin composition (B)]
Examples of the thermoplastic resin contained in the resin composition (B) include crystalline resins and amorphous resins. Examples of crystalline resins include polyethylene, polypropylene, and polybutene. Examples of amorphous resins include acrylonitrile-butadiene-styrene copolymer resin (ABS resin), polyvinyl chloride resin, and the like. Amorphous resins are preferred as thermoplastic resins because they can be bonded with an adhesive. In addition, from the viewpoint of flame retardancy, polyvinyl chloride resins are more preferred as thermoplastic resins.
Examples of polyvinyl chloride resins include polyvinyl chloride homopolymers, copolymers of vinyl chloride monomers with other monomers having unsaturated bonds copolymerizable with vinyl chloride monomers, graft copolymers in which vinyl chloride monomers are graft copolymerized onto polymers other than polyvinyl chloride resins, etc. The polyvinyl chloride resins may be used alone or in combination of two or more.
The polyvinyl chloride resin may be further chlorinated. Examples of methods for chlorinating polyvinyl chloride resin include thermal chlorination and photochlorination.

Examples of other monomers having an unsaturated bond copolymerizable with the vinyl chloride monomer include α-olefins such as ethylene, propylene, and butylene; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as butyl vinyl ether and cetyl vinyl ether; (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, and butyl acrylate; aromatic vinyls such as styrene and α-methylstyrene; and N-substituted maleimides such as N-phenylmaleimide and N-cyclohexylmaleimide. One of the other monomers may be used alone, or two or more may be used in combination.

Examples of polymers that can be graft-copolymerized with the vinyl chloride monomer include ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-carbon monoxide copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate-carbon monoxide copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, acrylonitrile-butadiene copolymer, polyurethane, chlorinated polyethylene, and chlorinated polypropylene. These polymers may be used alone or in combination of two or more.

The polyvinyl chloride resin may be crosslinked. Examples of methods for crosslinking polyvinyl chloride resins include adding a crosslinking agent and peroxide, irradiating with electron beams, and using a water-crosslinkable material.

The average degree of polymerization of the polyvinyl chloride resin is preferably from 400 to 1600, and more preferably from 600 to 1400. Here, the average degree of polymerization is the average degree of polymerization measured in accordance with JIS K-6721:1999 "Testing methods for vinyl chloride resins" using a resin sample obtained by dissolving the polyvinyl chloride resin in tetrahydrofuran (THF), removing insoluble components by filtration, and then drying and removing the THF in the filtrate.
When the average degree of polymerization of the polyvinyl chloride resin is equal to or greater than the lower limit, the mechanical strength can be sufficiently increased, and when it is equal to or less than the upper limit, sufficient moldability can be ensured.

Furthermore, the resin composition (B) may contain additives such as lubricants, processing aids, impact modifiers, heat resistance improvers, antioxidants, heat stabilizers, heat stabilization aids, light stabilizers, ultraviolet absorbers, pigments, plasticizers, and thermoplastic elastomers, as long as the effects of the present invention are not impaired.
The additives described below may be used alone or in combination of two or more.

The lubricant includes an internal lubricant and an external lubricant.
Examples of internal lubricants include butyl stearate, lauryl alcohol, stearyl alcohol, epoxidized soybean oil, glycerin monostearate, stearic acid, and bisamide.
Examples of external lubricants include paraffin wax, polyolefin wax, ester wax, and Montan acid wax.

Examples of processing aids include alkyl acrylate-alkyl methacrylate copolymers with a mass average molecular weight of 100,000 to 2,000,000. Examples of alkyl acrylate-alkyl methacrylate copolymers include n-butyl acrylate-methyl methacrylate copolymers and 2-ethylhexyl acrylate-methyl methacrylate-butyl methacrylate copolymers.

Examples of impact modifiers include methyl methacrylate-butadiene-styrene copolymer (MBS), chlorinated polyethylene, and acrylic rubber.
Examples of the heat resistance improver include α-methylstyrene resins and N-phenylmaleimide resins.

Examples of antioxidants include phenol-based antioxidants and phosphorus-based antioxidants.

Examples of the heat stabilizer include lead-based stabilizers, tin-based stabilizers, Ca—Zn-based stabilizers, higher fatty acid metal salts, etc. One type of heat stabilizer may be used alone, or two or more types may be used in combination.
Examples of lead-based stabilizers include white lead, basic lead sulfite, tribasic lead sulfate, dibasic lead phosphite, dibasic lead phthalate, tribasic lead maleate, silica gel coprecipitated lead silicate, dibasic lead stearate, lead stearate, and lead naphthenate.
Examples of tin-based stabilizers include mercaptides such as dibutyltin mercapto, dioctyltin mercapto, and dimethyltin mercapto; malates such as dibutyltin maleate, dibutyltin maleate polymer, dioctyltin maleate, and dioctyltin maleate polymer; and carboxylates such as dibutyltin mercaptodibutyltin laurate and dibutyltin laurate polymer.
The Ca-Zn stabilizer is a mixture of a fatty acid salt of calcium and a fatty acid salt of zinc. Examples of the fatty acid include behenic acid, stearic acid, lauric acid, oleic acid, palmitic acid, ricinoleic acid, and benzoic acid, and two or more of these may be used in combination.
Examples of higher fatty acid metal salts include lithium stearate, magnesium stearate, calcium stearate, calcium laurate, calcium ricinoleate, strontium stearate, barium stearate, barium laurate, barium ricinoleate, cadmium stearate, cadmium laurate, cadmium ricinoleate, cadmium naphthenate, cadmium 2-ethylhexoate, zinc stearate, zinc laurate, zinc ricinoleate, zinc 2-ethylhexoate, lead stearate, dibasic lead stearate, and lead naphthenate.
Among these, tin-based stabilizers or Ca—Zn-based stabilizers are preferred, and as tin-based stabilizers, those that do not contain sulfur, such as malates and carboxylates, are particularly preferred in order to prevent sulfide contamination, and as Ca—Zn-based stabilizers, stearates are particularly preferred in terms of the balance between lubricity and plate-out during molding processing.

The content of the heat stabilizer is preferably 0.3 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of the thermoplastic resin. If the content of the heat stabilizer is above the lower limit, the thermal stability of the thermoplastic resin during molding can be improved. If the content is below the upper limit, the thermoplastic resin can be sufficiently carbonized during combustion, resulting in sufficient fire resistance.

Examples of the heat stabilization aid include epoxidized soybean oil, phosphate ester, polyol, hydrotalcite, and zeolite.
Examples of the light stabilizer include hindered amine light stabilizers.
Examples of the ultraviolet absorber include salicylic acid ester-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers.

Examples of pigments include organic pigments such as azo pigments, phthalocyanine pigments, threne pigments, and dye lakes; and inorganic pigments such as oxide pigments, molybdenum chromate pigments, sulfide/selenide pigments, and ferrocyanide pigments.

Examples of plasticizers include dibutyl phthalate, di-2-ethylhexyl phthalate, and di-2-ethylhexyl adipate. However, because plasticizers tend to reduce the heat resistance and fire resistance of molded products, it is preferable to use a small amount of plasticizer.

Examples of thermoplastic elastomers include acrylonitrile-butadiene copolymer (NBR), ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl acetate-carbon monoxide copolymer (EVACO), vinyl chloride-based thermoplastic elastomers such as vinyl chloride-vinyl acetate copolymer and vinyl chloride-vinylidene chloride copolymer, styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, urethane-based thermoplastic elastomers, polyester-based thermoplastic elastomers, and polyamide-based thermoplastic elastomers.

The thermal expansion onset temperature of the thermally expandable graphite contained in the resin composition (B) is preferably 200°C or higher and 285°C or lower, more preferably 210°C or higher and 285°C or lower, and even more preferably 240°C or higher and 285°C or lower. The tube 30 can be formed, for example, by extruding the resin composition through a mold into a tubular shape. During this process, the resin composition flows around the circumferential direction within the mold. Therefore, weld lines extending in the axial direction of the tube 30 are formed at positions where the resin compositions butt against each other after the resin composition flows around. If the thermal expansion onset temperature is equal to or higher than the lower limit, the temperature during extrusion through the mold during production of the tube 30 can be increased, resulting in adhesion at the weld line and increased compressive strength. Additionally, if the thermal expansion onset temperature is equal to or higher than the lower limit, gas generation due to expansion of the thermally expandable graphite during production of the tube 30 is suppressed, resulting in good adhesion at the weld line and increased compressive strength.
The thermal expansion starting temperature of thermally expandable graphite is the temperature at which the thermally expandable graphite expands to at least 1.1 times its volume before the start of heating when the temperature is increased from 150° C. at a rate of 5° C./min. The temperature interval at which the volume of the thermally expandable graphite is measured is not particularly limited, and the volume may be measured, for example, every time the temperature increases by 5° C.
A thermal expansion initiation temperature equal to or higher than the lower limit is sufficiently higher than the molding temperature when resin composition (B) is molded to produce pipe 30. Therefore, when the thermal expansion initiation temperature of the thermally expandable graphite is equal to or higher than the lower limit, expansion of the thermally expandable graphite can be prevented when resin composition (B) is molded.

Thermal expandable graphite is flaky graphite, and is flat and plate-like. The flaky shape of thermal expandable graphite allows it to expand sufficiently when heated. Note that flaky means thin or flat, and for example, has an aspect ratio of 5 or more, as described below.

The thermally expandable graphite preferably has a degree of expansion of 180 cm ³ /g or more, and more preferably 185 cm ³ /g or more, at 1000° C. Here, the degree of expansion of the thermally expandable graphite at 1000° C. refers to the volume (cm ³ ) per unit mass (g) after the thermally expandable graphite is held at 1000° C. for 10 seconds.
If the degree of expansion of the thermally expandable graphite is equal to or greater than the lower limit, it will expand sufficiently, so that the compartment penetration portion 2a can be more reliably closed in the event of a fire.
The thermally expandable graphite preferably has a degree of expansion at 1000° C. of 240 cm ³ /g or less, since this facilitates the production of the thermally expandable graphite.

The thermally expandable graphite described above can be obtained by treating graphite powder with an inorganic acid and an oxidizing agent. This treatment allows for the production of a crystalline compound in which the inorganic acid is intercalated between the graphite layers. The crystalline compound in which the inorganic acid is intercalated between the graphite layers has thermal expandability.
Examples of the graphite include natural flaky graphite, pyrolytic graphite, and kish graphite.
Examples of the inorganic acid include concentrated sulfuric acid, nitric acid, and selenic acid.
Examples of the oxidizing agent include concentrated nitric acid, perchloric acid, perchlorates, permanganates, dichromates, and hydrogen peroxide.
After the graphite powder has been treated with the inorganic acid and the oxidizing agent, it may be subjected to a neutralization treatment to reduce the acidity.

The pH of the thermally expandable graphite is preferably 2 or more and 10 or less, more preferably 2.5 or more and 8 or less. When the resin composition (B) contains a heat-absorbing agent having hydroxide ions, such as magnesium hydroxide or aluminum hydroxide, as a flame retardant, the hydroxide ions of the flame retardant neutralize with the acidic substance to produce water (neutralized water). The hydroxide ions used in the endothermic condensation reaction of hydroxide ions are reduced by the neutralization reaction during molding, thereby reducing the amount of heat absorbed in the event of a fire. In addition, vaporization of the neutralized water may cause bubbles. Therefore, by setting the pH of the thermally expandable graphite to be equal to or greater than the above-mentioned lower limit, neutralization with the flame retardant can be suppressed. When the pH of the thermally expandable graphite is equal to or less than the above-mentioned upper limit, the thermally expandable graphite is less likely to be neutralized, resulting in better expansion.
The method for adjusting the pH of the thermally expandable graphite is not particularly limited. For example, when producing the thermally expandable graphite, there may be mentioned a method in which graphite powder is treated with an inorganic acid and an oxidizing agent, and then the treatment is repeated with water washing and drying to adjust the pH of the thermally expandable graphite.
The pH of the thermally expandable graphite is a value measured by the following method.
5 g of the collected thermally expandable graphite and 25 ml of ion-exchanged water are placed in a beaker to prepare a graphite mixture. The prepared graphite mixture is stirred for 30 seconds, allowed to stand for 20 minutes, and then the pH of the graphite mixture is measured using a pH meter ("pH/ION METER F-23" manufactured by Horiba, Ltd.).

The thermally expandable graphite preferably has an average particle size of 10 μm or more and 1000 μm or less, more preferably 100 μm or more and 700 μm or less, and an average thickness of 100 μm or less.
The average particle size of the thermally expandable graphite is the 50% particle size in the cumulative particle size distribution on a volume basis, which is determined by sieving the thermally expandable graphite using a test sieve according to JIS Z8801-1.

The average aspect ratio of the thermally expandable graphite is 5 or more and 40 or less, preferably 10 or more and 35 or less, and more preferably 20 or more and 35 or less. That is, the thermally expandable graphite is a flat flake. When the aspect ratio is equal to or greater than the above-mentioned lower limit, the degree of expansion tends to be low. When the aspect ratio is equal to or less than the above-mentioned upper limit, the thermal conductivity can be further reduced. In addition, when the tube 30 has a multilayer structure, when the aspect ratio is equal to or less than the above-mentioned upper limit, the difference in linear expansion coefficient between layers containing thermally expandable graphite and layers not containing thermally expandable graphite can be reduced. This can suppress molding defects such as peeling between the intermediate layer and the surface layer due to shrinkage differences caused by cleaning the inside of the tube 30 or the heat of high-temperature wastewater, or warping of the tube 30 due to a large difference in shrinkage between the surface layer and the intermediate layer after molding.
The thermally expandable graphite, which is a flat flake, is oriented in the circumferential direction of the tube 30. At the position of the weld line, the thermally expandable graphite tends to be oriented in the radial direction of the tube 30. Therefore, at the position of the weld line, flat surfaces of the thermally expandable graphite face each other, making it easier for cracks to occur. If the aspect ratio is equal to or less than the above upper limit, the area of the thermally expandable graphite facing each other at the position of the weld line becomes smaller, and the compressive strength can be increased.

The linear expansion coefficient of the rigid polyvinyl chloride resin constituting the pipe 30 is 7.0×10 ⁻⁵ /°C as measured by thermomechanical analysis (TMA) specified in JIS K 7197:2012, but the linear expansion coefficient of the pipe 30 of this embodiment is 4.5×10 ⁻⁵ /°C or more and less than 7.0×10 ⁻⁵ /°C, preferably 5.0×10 ⁻⁵ /°C or more and less than 7.0×10 ⁻⁵ /°C, and more preferably 5.5×10 ⁻⁵ /°C or more and less than 6.8×10 ⁻⁵ /°C. The difference in linear expansion coefficient between the surface layer, inner layer and intermediate layer is 2.5×10 ⁻⁵ /°C or less, preferably 2.0×10 ⁻⁵ /°C or less, and more preferably 1.0×10 ⁻⁵ /°C or less.

Furthermore, the fusion strength between the surface layer and inner layer of the pipe 30 and the intermediate layer is preferably 1.5 MPa or more, and more preferably 2.0 MPa or more. The higher the fusion strength, the easier it is to increase the compressive strength of the pipe 30. The fusion strength between the surface layer and inner layer and the intermediate layer can be adjusted by combining the aspect ratio of the thermally expandable graphite, the amount of thermally expandable graphite, and the degree of vacuum in the sizing device in the manufacturing method described below.

The average aspect ratio is the ratio of the length of the longest part in a plan view to the thickness. Since the thermally expandable graphite used in this invention is generally flat, if the thickness direction is considered to be the vertical direction and the radial direction is considered to be the horizontal direction, the aspect ratio is the value obtained by dividing the maximum horizontal dimension by the vertical thickness.

The aspect ratio is then measured for a sufficiently large number of graphite pieces, i.e., at least 10 or more, and the average value is taken as the average aspect ratio. More specifically, the thermally expandable graphite is observed using an FE-SEM, the image is imported into image processing software (Photoshop (registered trademark) manufactured by Adobe Systems Incorporated), and the maximum dimension and thickness are measured using a length measurement tool. When measuring the maximum dimension of graphite particles before they are added to a resin composition, the maximum dimension is taken as the longest side of a rectangle circumscribing the graphite particles. When measuring the maximum dimension of graphite particles after they are added to a resin composition, the tube 30 is cut and the cross section is observed, and the longest side is taken as the maximum dimension, or graphite particles are extracted from the tube 30 and the longest side of a rectangle circumscribing the extracted graphite particles is taken as the maximum dimension. Specific dimensions can also be measured by measuring the scale bar in the FE-SEM image in the same manner.

The maximum horizontal dimension of thermally expandable graphite and the thickness of exfoliated graphite can be measured, for example, using a field emission scanning electron microscope (FE-SEM).

The content of thermally expandable graphite in resin composition (B) is preferably 3.0 to 20.0 parts by mass, more preferably 4.0 to 18.0 parts by mass, even more preferably 4.0 to 15.0 parts by mass, and particularly preferably 4.0 to less than 10.0 parts by mass, per 100 parts by mass of thermoplastic resin. When the content of thermally expandable graphite in resin composition (B) is equal to or greater than the lower limit, sufficient expansion of pipe 30 (particularly second vertical pipe 32) is possible in the event of a fire, further improving the fire resistance of compartment penetration portion 2a. On the other hand, when the content of thermally expandable graphite in resin composition (B) is equal to or less than the upper limit, excessive expansion of pipe 30 can be prevented, preventing the pipe 30 from breaking and reducing its fire resistance. Additionally, when the content of thermally expandable graphite in resin composition (B) is equal to or less than the upper limit, the thermal conductivity of pipe 30 can be reduced, and the pressure resistance and compressive strength can be further increased.

Furthermore, the resin composition (B) preferably contains a flame retardant in addition to the thermally expandable graphite. The flame retardant in the resin composition (B) is a compound that exhibits an endothermic effect when heated to suppress temperature rise, or a compound that melts when heated to suppress the supply of oxygen and the generation of combustible gases. For example, a compound that undergoes an endothermic reaction such as a dehydration reaction when heated can be used as the flame retardant.
Examples of heat-absorbing agents include inorganic hydroxides such as magnesium hydroxide, aluminum hydroxide, kaolin minerals (kaolinite, halloysite, dickite) and hydrotalsalcite, and inorganic compounds with water absorption properties such as sepiolite, bentonite, montmorillonite, talc, mica, quartz, zeolite, wollastonite, and nepheline syenite. Hereinafter, inorganic hydroxides and inorganic compounds that undergo a dehydration reaction when heated will be collectively referred to as "thermally dehydrated compounds." In thermally dehydrated compounds, the temperature rise can also be suppressed by the latent heat of vaporization of water generated by the dehydration reaction.
Among the thermally dehydrated compounds, magnesium hydroxide undergoes a dehydration reaction at 300°C or higher. Therefore, when magnesium hydroxide is used as a flame retardant, the occurrence of a dehydration reaction can be suppressed when the resin composition (B) is molded to produce the pipe 30.
Among the thermally dehydrated compounds, aluminum hydroxide undergoes a dehydration reaction at about 200°C. Therefore, when aluminum hydroxide is used as a flame retardant, it can quickly absorb the heat transferred to the pipe 30 in the event of a fire.

Among the thermally dehydrated compounds, hydrotalcite has the chemical name magnesium aluminum hydroxide carbonate hydrate, and is a type of mineral represented by Mg ₆ Al ₂ (OH) _{16 CO} 3.4H ₂ O, etc. It is a layered inorganic compound consisting of a positively charged basic layer [Mg _1-x Al _x (OH) ₂ ] ^x+ and a negatively charged intermediate layer [(CO ₃ ) _x/ 2.mH ₂ O] ^x- . Many divalent and trivalent metals have a similar layered structure, and these are represented by the following general formula:
[M ²⁺ _1-x M ³⁺ _x (OH) ₂ ] ^x+ [A ^n- _x/n・mH ₂ O] ^x-
M ²⁺ : divalent metal ion such as Mg ²⁺ or Zn ²⁺ M ³⁺ : trivalent metal ion such as Al ³⁺ or Fe ³⁺ A ^n- : n-valent anion such as CO ₃ ^2- , Cl ^- or NO ₃ ^- X: 0<X≦0.33
In hydrotalcite, the water of crystallization present between molecules begins to dehydrate at approximately 180°C, and the water of crystallization is completely eliminated at approximately 300°C. Up to this state, synthetic hydrotalcite maintains its crystalline structure, but above approximately 350°C, the crystalline structure begins to collapse, releasing water and carbon dioxide. Furthermore, synthetic hydrotalcite begins its endothermic decomposition at a temperature that is 60°C to 75°C lower than the thermal decomposition temperature of vinyl chloride resin, which is approximately 200°C to 300°C. Therefore, the endothermic decomposition of vinyl chloride resin can be efficiently suppressed by the endothermic decomposition of hydrotalcite.
The flame retardant may be a combination of at least two of magnesium hydroxide, aluminum hydroxide, kaolin-based minerals, and hydrotalcite.

The heat-dehydrated compound is usually in the form of particles.
The volume average particle diameter of the thermally dehydrated compound is preferably 0.01 μm or more and 20 μm or less, more preferably 0.05 μm or more and 2 μm or less, and even more preferably 0.05 μm or more and 1 μm or less. By setting the volume average particle diameter of the thermally dehydrated compound within this range, it is possible to impart transparency to the tube 30 and improve the dispersibility of the thermally dehydrated compound. The volume average particle diameter is a value measured using a laser diffraction/scattering particle size distribution measuring device.
The BET specific surface area of the thermally dehydrated compound is preferably 1 m ² /g or more and 40 m ² /g or less, and more preferably 1 m ² /g or more and 20 m ² /g or less. Here, the BET specific surface area is a value determined using nitrogen adsorption.
When the volume average particle diameter and BET specific surface area of the thermally dehydrated compound are within the above ranges, the compound can fully exhibit its effect as a flame retardant, and the moldability of the resin composition (B) when producing the pipe 30 and the mechanical properties of the pipe 30 can be fully ensured.

The particle surface of the thermally dehydrated compound is preferably surface-treated with a surface treatment agent such as a higher fatty acid such as stearic acid or a silane coupling agent. The thermally dehydrated compound surface-treated with a surface treatment agent has high dispersibility in thermoplastic resins and is more likely to exhibit its endothermic effect. Furthermore, when the thermally dehydrated compound is basic, it can make the thermoplastic resin less susceptible to scorching and prevent yellowing.
When the thermally dehydrated compound is surface-treated with a surface treatment agent, the amount of the surface treatment agent is preferably 0.05 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of the thermally dehydrated compound. When the amount of the surface treatment agent is equal to or more than the lower limit, the dispersibility of the thermally dehydrated compound in the thermoplastic resin can be sufficiently increased, and when the amount is equal to or less than the upper limit, a decrease in economic efficiency can be suppressed.

Examples of flame retardants other than heat-absorbing agents include hydrotalcite, antimony oxide, molybdenum compounds, bromine-based compounds, phosphorus-based compounds, and boric acid-based compounds.
Examples of antimony oxide include antimony dioxide, antimony trioxide, and antimony pentoxide.
Examples of molybdenum compounds include molybdenum trioxide, molybdenum disulfide, and ammonium molybdate.
Examples of the brominated compounds include tetrabromobisphenol A, tetrabromoethane, tetrabromoethane, and tetrabromoethane.
Examples of phosphorus compounds include red phosphorus, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, xylenyl diphenyl phosphate, sodium phosphate, potassium phosphate, magnesium phosphate, zinc phosphate, and ammonium polyphosphate.
Examples of boric acid compounds include calcium borate and zinc borate.
Among the flame retardants, phosphorus compounds and antimony trioxide are preferred because they have a high effect of inhibiting the combustion of polyvinyl chloride resin.
These flame retardants may be used alone or in combination of two or more.

The flame retardant in the resin composition (B) is preferably a thermally dehydrated compound such as aluminum hydroxide, magnesium hydroxide, or magnesium carbonate, or a molybdenum compound, a bromine-based compound, a phosphorus-based compound, or a boric acid-based compound. When such a flame retardant is contained, the fire resistance of the pipe 30 can be further improved.
The content of the flame retardant in the resin composition (B) is preferably 0.05 parts by mass or more and 10 parts by mass or less, more preferably 1 part by mass or more and 5 parts by mass or less, per 100 parts by mass of the thermoplastic resin.
Furthermore, the content of the flame retardant is preferably 13 parts by mass or more and 215 parts by mass or less, more preferably 13 parts by mass or more and 190 parts by mass or less, even more preferably 17 parts by mass or more and 130 parts by mass or less, and most preferably 40 parts by mass or more and 120 parts by mass or less, relative to 100 parts by mass of the thermally expandable graphite contained in the thermoplastic resin.
If the content of the flame retardant is equal to or greater than the lower limit, the fire resistance can be further improved, and if it is equal to or less than the upper limit, the mechanical strength of the pipe 30 can be sufficiently increased.
In particular, when part or all of the flame retardant is a phosphorus-based compound, the mechanical strength is likely to decrease. Therefore, the content of the phosphorus-based compound is preferably 1 part by mass or more but less than 200 parts by mass, and more preferably 13 parts by mass or more but 150 parts by mass or less, per 100 parts by mass of the thermally expandable graphite contained in the thermoplastic resin.

The volume average particle size of the flame retardant is preferably 0.2 μm or more and 100 μm or less, and more preferably 0.4 μm or more and 50 μm or less, as measured by a light scattering particle size meter (DLS-7000 light scattering particle size meter, manufactured by Otsuka Electronics Co., Ltd.).
When the resin composition (B) contains a flame retardant, the ratio of the average particle size α of the thermally expandable graphite to the volume average particle size β of the flame retardant (β/α ratio) is preferably 0.0015 or more and 0.0065 or less, more preferably 0.002 or more and 0.006 or less. The flame retardant acts as a thermal bridge between the thermally expandable graphite particles. If the β/α ratio is within the above range, the thermal bridge is prevented, and the thermal conductivity can be further reduced.

Resin composition (B) may contain a thermal stabilizer. Examples of thermal stabilizers include lead-based stabilizers, tin-based stabilizers, Ca-Zn-based stabilizers, and higher fatty acid metal salts. One type of thermal stabilizer may be used alone, or two or more types may be used in combination.

Examples of lead-based stabilizers include white lead, basic lead sulfite, tribasic lead sulfate, dibasic lead phosphite, dibasic lead phthalate, tribasic lead maleate, silica gel coprecipitated lead silicate, dibasic lead stearate, lead stearate, and lead naphthenate.
Examples of tin-based stabilizers include mercaptides such as dibutyltin mercapto, dioctyltin mercapto, and dimethyltin mercapto; malates such as dibutyltin maleate, dibutyltin maleate polymer, dioctyltin maleate, and dioctyltin maleate polymer; and carboxylates such as dibutyltin mercaptodibutyltin laurate and dibutyltin laurate polymer.
The Ca-Zn stabilizer is a mixture of a fatty acid salt of calcium and a fatty acid salt of zinc. Examples of the fatty acid include behenic acid, stearic acid, lauric acid, oleic acid, palmitic acid, ricinoleic acid, and benzoic acid, and two or more of these may be used in combination.
Examples of higher fatty acid metal salts include lithium stearate, magnesium stearate, calcium stearate, calcium laurate, calcium ricinoleate, strontium stearate, barium stearate, barium laurate, barium ricinoleate, cadmium stearate, cadmium laurate, cadmium ricinoleate, cadmium naphthenate, cadmium 2-ethylhexoate, zinc stearate, zinc laurate, zinc ricinoleate, zinc 2-ethylhexoate, lead stearate, dibasic lead stearate, and lead naphthenate.

The content of the heat stabilizer is preferably 0.3 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of the thermoplastic resin. If the content of the heat stabilizer is above the lower limit, the thermal stability of the thermoplastic resin during molding can be improved. If the content is below the lower limit, the thermoplastic resin can be sufficiently carbonized during combustion, resulting in sufficient fire resistance.

The resin composition (B) preferably contains an inorganic filler in addition to the thermally expandable graphite.
Examples of inorganic fillers include inorganic compounds other than the flame retardants, such as silica, diatomaceous earth, alumina, zinc oxide, titanium oxide, calcium oxide, magnesium oxide, iron oxide, tin oxide, antimony oxide, ferrites, calcium hydroxide, basic magnesium carbonate, calcium carbonate, zinc carbonate, barium carbonate, dawnnite, hydrotalcite, calcium sulfate, barium sulfate, gypsum fiber, calcium silicate, talc, clay, mica, montmorillonite, bentonite, activated clay, sepiolite, imogolite, sericite, glass fiber, glass beads, silica-based balun, aluminum nitride, boron nitride, silicon nitride, carbon black, graphite, carbon fiber, carbon balun, charcoal powder, various metal powders, potassium titanate, magnesium sulfate, lead zirconate titanate, aluminum borate, molybdenum sulfide, silicon carbide, stainless steel fiber, zinc phosphate, zinc borate, various magnetic powders, slag fiber, fly ash, and dewatered sludge. Of the inorganic fillers, basic inorganic fillers such as calcium carbonate, calcium silicate, calcium hydroxide, calcium oxide, magnesium oxide, barium carbonate, zinc oxide, zinc hydroxide, and iron oxide are preferred.
The inorganic fillers may be used alone or in combination of two or more.

The content of the inorganic filler is preferably 0.3 parts by mass or more and 50.0 parts by mass or less, and more preferably 1.0 parts by mass or more and 5.0 parts by mass or less, relative to 100 parts by mass of the thermoplastic resin. If the content of the inorganic filler is equal to or more than the lower limit, the fire resistance can be further improved, and if it is equal to or less than the upper limit, the mechanical strength of the pipe 30 can be sufficiently high.
In particular, when thermally expandable graphite having a pH adjusted to 1.5 or more and 4.0 or less is used, the resin composition (B) preferably contains the basic inorganic filler in a proportion of 0.3 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of the thermoplastic resin. If the content ratio of the basic inorganic filler is equal to or more than the lower limit, the thermal stability when molding the resin composition (B) to produce the pipe 30 is improved, and the generation of char during molding can be prevented. If the content ratio is equal to or less than the upper limit, the thermoplastic resin can be sufficiently carbonized in the event of a fire, and fire resistance can be further improved.

As explained above, with the joint 20 according to this embodiment, the linear expansion coefficient of the sound-insulating cover 22 in the short direction B is smaller than the linear expansion coefficient of the sound-insulating cover 22 in the longitudinal direction A. Therefore, the sound-insulating cover 22 is less likely to expand in the axial direction. This makes it possible to suppress deflection of the sound-insulating cover 22.

The linear expansion coefficient of the sound-insulating cover 22 in the short-side direction B is 800×10 ⁻⁶ (1/° C.) or less, which makes it possible to reliably suppress deflection of the sound-insulating cover 22 .

Generally, the linear expansion coefficient increases in the extrusion direction MD of the original web 50 of the sound-insulating cover 22, while the linear expansion coefficient decreases in the orthogonal direction TD of the original web 50 of the sound-insulating cover 22.
Here, the longitudinal direction A of the sound-insulating cover 22 is the extrusion direction MD of the original web 50 of the sound-insulating cover 22. Therefore, the lateral direction B of the sound-insulating cover 22 is the orthogonal direction TD of the original web 50 of the sound-insulating cover 22. This reliably reduces the linear expansion coefficient of the sound-insulating cover 22 in the lateral direction B.

The technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

The materials of the joint body 21, the sound insulating cover 22, and the pipe 30 are not limited to those shown in the above embodiment.
The space S does not have to be annular and continuous in the circumferential direction.

In addition, the components in the above embodiments may be replaced with well-known components as appropriate, and the above-described modifications may be combined as appropriate, without departing from the spirit of the present invention.

Next, a verification test for verifying the effects of the above embodiment will be described below.
In this verification test, a total of five types of joints 20 were prepared: Examples 1 to 4 and Comparative Example 1. The external shapes of Examples 1 to 4 and Comparative Example 1 were the same as those of the joint 20 according to the embodiment described with reference to Figures 1 and 2.
In Examples 1 to 4, as shown in Fig. 3, the longitudinal direction A of the sound-insulating cover 22 is the extrusion direction MD of the raw web 50. On the other hand, in Comparative Example 1, as shown in Fig. 5, the longitudinal direction A of the sound-insulating cover 22A is the orthogonal direction TD of the raw web 50.
The configuration of the sound-insulating cover 22 of the joint 20 according to each example and comparative example, and the results of the evaluation of fire resistance, are shown in Table 1 below.

The linear expansion coefficient (TD) in the above table is the linear expansion coefficient in the transverse direction TD of the original sheet 50 of the sound-insulating cover 22. For Examples 1 to 4, the linear expansion coefficient (TD) is the linear expansion coefficient in the short direction B of the sound-insulating cover 22 (the linear expansion coefficient in the up-down direction Z of the sound-insulating cover 22). For Comparative Example 1, the linear expansion coefficient (TD) is the linear expansion coefficient in the longitudinal direction A of the sound-insulating cover 22 (the linear expansion coefficient in the circumferential direction of the sound-insulating cover 22).
The linear expansion coefficient (MD) in the above table is the linear expansion coefficient in the extrusion direction MD (machine direction) of the raw web 50 of the sound-insulating cover 22. For Examples 1 to 4, the linear expansion coefficient (MD) is the linear expansion coefficient in the longitudinal direction A of the sound-insulating cover 22 (the linear expansion coefficient in the circumferential direction of the sound-insulating cover 22). For Comparative Example 1, the linear expansion coefficient (MD) is the linear expansion coefficient in the lateral direction B of the sound-insulating cover 22 (the linear expansion coefficient in the up-down direction Z of the sound-insulating cover 22).

The fire resistance evaluation was performed using a fire resistance test furnace 100 shown in FIG. 6 . The fire resistance test furnace 100 includes a heating chamber 110, which is sealed except for its upper portion, a test floor slab 120 installed on top of the heating chamber 110, a burner 130 installed within the heating chamber 110 to generate a flame, and a thermocouple 140 for measuring the temperature within the heating chamber 110. The floor slab 120 was a 100 mm thick precast concrete (PC) panel with a compartment penetration 120a having a diameter of 260 mm. The thermocouple 140 was positioned so that it could measure the temperature near the lower end of the second vertical pipe 32 within the heating chamber 110. Mortar 3 was filled between the joint 20 and the inner surface of the compartment penetration 120a to seal the compartment penetration 120a.
The piping structure 10 was installed in this fire resistance test furnace 100 in the same arrangement as in the above embodiment.
Then, a fire resistance test (based on ISO 834-1, an evaluation method for fire resistance performance tests under the revised Building Standards Act that came into effect on June 1, 2000) was conducted. In this fire resistance test, the time (smoke generation time) from the start of heating until smoke emerged from the gap between the joint 20 and the compartment penetration portion 120a was measured. In accordance with the Fire Service Act Ordinance 8 Compartment Judgment Criteria, if the smoke generation time was 120 minutes or more, fire resistance was recognized and the evaluation in Table 3 was "○", and if it was less than 120 minutes, fire resistance was not recognized and the evaluation in Table 3 was "×".

The above results confirm that the piping structures 10 of Examples 1 to 4 were fire-resistant, with no smoke escaping between the pipe fitting 20 and the compartment penetration portion 120a even after 120 minutes had passed since the start of heating (see the cross-sectional view of the fitting 20 of the Example in Figure 7 for the state). On the other hand, the piping structure 10 of Comparative Example 1 emitted smoke within 120 minutes of the start of heating (see the cross-sectional view of the fitting 20A of the Comparative Example in Figure 8 for the state).

20 Joint 21 Joint body 22 Sound insulation cover 23 Main pipe 24 Socket 30 Pipe 50 Raw material A Longitudinal direction B Shortitudinal direction S Space

Claims (4)

A joint body;
a sound-insulating cover made of an olefin resin that covers the joint body from the radial outside of the joint body,
A space is provided between the joint body and the sound-insulating cover,
The sound-insulating cover is long and is wrapped around the joint body,
The longitudinal direction of the sound-insulating cover is the circumferential direction of the joint body, and the lateral direction of the sound-insulating cover is the axial direction of the joint body,
A joint in which the linear expansion coefficient of the sound-insulating cover measured in a temperature range of 15°C to 25°C in the short direction is smaller than the linear expansion coefficient of the sound-insulating cover measured in a temperature range of 15°C to 25°C in the long direction. 2. The joint according to claim 1, wherein the sound-insulating cover has a linear expansion coefficient measured in a temperature range of 15° C. to 25° C. in the short-side direction of the sound-insulating cover of 800×10 ⁻⁶ (1/° C.) or less. a first vertical pipe;
A second vertical pipe;
A piping structure comprising: a joint for connecting the first vertical pipe and the second vertical pipe, the joint being the joint according to claim 1 or 2. The piping structure according to claim 3 , wherein the first vertical pipe and the second vertical pipe contain a thermoplastic resin and thermally expandable graphite.