JP7357711B2 - Thermal insulation coating material for heat medium conduits, thermal insulation coating composite material for heat medium conduits, and insulation coating method - Google Patents

Description

The invention of this application relates to a technique for thermally insulating a conduit that guides a heat medium, such as a refrigerant pipe that connects an indoor unit and an outdoor unit of an air conditioner, with a coating to keep the heat medium warm.

BACKGROUND ART In various air conditioning equipment and heating and cooling equipment, such as heat pump air conditioners, conduit systems are constructed to transport heat medium for cooling and heating. BACKGROUND ART Various factories, processing facilities, and the like have also formed conduit systems for transporting heat medium in order to heat or cool objects. Furthermore, conduit systems are also formed in refrigeration facilities, heat preservation facilities, and the like to transport heat medium.

In such a conduit system, a conduit made of metal such as copper or aluminum is used in consideration of strength. In order to prevent changes in the temperature of the heat medium circulating inside, the periphery of the conduit is covered with a heat-insulating covering material (thermally insulating covering material).
FIG. 9 is a schematic diagram showing a conventional insulation coating method when forming a conduit system.
To form the conduit system, as shown in FIG. 9(1), a unit (hereinafter referred to as a conduit unit) 4 consisting of a conduit 41 provided with a heat-retaining coating 42 is used. As the conduit unit 4, a straight conduit 41 having a length of 4 meters or a coiled conduit 41 having a length of 20 meters is generally used. The heat-insulating covering material 42 also has a similar length and covers the conduit 41 over almost its entire length. However, the length of the conduit 41 may be a little longer (about several centimeters) than the heat insulation covering material 42, and both ends may be slightly exposed.

When forming a conduit system, as shown in FIG. 9(2), the conduits 41 of the conduit unit 4 are first joined together by welding or the like. Thereafter, as shown in FIG. 9(3), the exposed portion of the conduit 41, including the joint portion, is covered with a short heat-insulating covering material (hereinafter referred to as auxiliary heat-insulating covering material) 44. The auxiliary heat insulation covering material 44 has a notch in the length direction, and is opened to cover the exposed portion of the conduit 41.

Thereafter, as shown in FIG. 9(4), the heat-retaining coverings 42 and 44 are fixed. A dedicated adhesive tape 43 as disclosed in Patent Document 1 is often used to fix the heat-insulating covering materials 42 and 44. A dedicated adhesive tape 43 is wound and bonded so as to span both ends of the auxiliary heat-insulating covering material 44 and the ends of each insulating covering 42, and the two are fixed so as not to separate.

Patent No. 5425332 Patent No. 6785328 International Publication 2015/133619 JP2012-97285A International publication 2019/073873

Polyolefin resin foams such as polyethylene resin foams are widely used as heat-insulating coating materials for the above-mentioned conduit systems. Although heat-retaining covering materials made of polyolefin resin foam are inexpensive and exhibit high thermal insulation properties, they initially suffer from dimensional changes due to heat, resulting in separation or breakage of bonded parts.

Specifically, a heat-insulating coating material made of a polyolefin resin foam has physical properties such that the resin itself expands at high temperatures and contracts at low temperatures. However, if the product is exposed to high temperatures after it has been used as a product, initial heat shrinkage may occur. This initial heat shrinkage is caused by manufacturing factors. That is, the heat-insulating coating material is often manufactured by rolling a sheet-shaped resin by rolling and processing the resin into a cylindrical shape. At this time, thermal strain (tensile stress) from rolling may remain, and when heated to the same extent during use, a force (stress relaxation) that tries to eliminate the strain acts. This force acts to cause the member to contract, and if tensile stress remains in the axial direction of the heat-insulating coating, the member will tend to contract in the axial direction when heated to about the rolling temperature. This force is much larger than the thermal expansion force due to the physical properties of the material itself, and a strong force acts on the heat-retaining coating material to cause it to contract in the axial direction. As a result, accidents such as separation or breakage of the bonded portions of the heat-insulating covering materials are likely to occur.

Note that the polyolefin resin foam conventionally used as a heat-retaining covering material has very low elasticity. That is, even if it is pulled or pushed with the average force of an adult male (for example, 30 kPa), the length ratio is less than 5%, and there is almost no expansion or contraction. Therefore, properties such as elastic expansion to compensate for thermal contraction cannot be expected.

In conventional conduit systems that use low-elastic thermal insulation materials, if an accident occurs such as separation or rupture of a joint due to thermal contraction, the conduit is not covered in that area, which reduces the thermal insulation effect. . This reduces the efficiency of heating, cooling, and air conditioning. Furthermore, in freezing and refrigeration equipment, the efficiency of freezing and refrigeration is reduced. A particular problem is that dew condensation forms on the exposed portion of the conduit and drips onto equipment located below, damaging the equipment or causing stains or other contamination.

Patent Document 2 proposes a structure in which a thick highly elastic heat-retaining covering material is interposed between the two. According to this structure, the force caused by thermal deformation of the low-elastic heat-insulating covering material is alleviated by the elongation of the high-elastic heat-insulating covering material. Therefore, there is no problem that the bonded portions of the heat-retaining covering materials become separated or break.

However, according to studies conducted by the inventors, it has been found that even in the case of the structure of Patent Document 2, problems may occur in the case of a conduit system that has a larger thermal contraction. That is, in the structure of Patent Document 2, when thermal contraction occurs in the low-elasticity heat-insulating covering material, the high-elastic heat-insulating covering material stretches as if being pulled by it. In this case, if large tensile stress remains due to factors during manufacturing, or if the overall amount (length) of thermal contraction is large due to the long route of the conduit system, the amount of elongation of the highly elastic thermal insulation material also becomes larger. An increase in the amount of elongation means that the restoring force also increases (Hooke's law), and there is a large force at the joint between the low-elasticity insulation material and the high-elasticity insulation material that tries to separate them. act. As a result, the bonded portions are likely to become partially separated or break due to unbearable resistance. Even if breakage does not occur, the separation reduces the thermal insulation of the area, and condensation is likely to occur in that area due to the influence of the low-temperature refrigerant.

The invention of this application was made in order to solve the above-mentioned problems, and aims to prevent problems such as dew condensation from occurring even when a larger heat shrinkage occurs in the heat insulation coating material. .

In order to solve the above problems, this specification discloses inventions of a thermal insulation coating material for heat medium conduits, a thermal insulation coating composite material for heat medium conduits, and an insulation coating method.
The heat-insulating coating material for a heat-medium conduit according to the disclosed invention is a heat-insulating coating material for a cylindrical heat-medium conduit that covers the conduit that guides the heat medium on the outside , and has an expansion ratio of 35 times or more and 60 times or less. It has a base material made of polyolefin resin foam. The base material (excluding those in which air bubbles are exposed on the outer surface by slicing) has a wall thickness that is more than half of the total wall thickness. This thermal insulation coating material for heat medium conduits has a compressibility that allows it to be compressed by more than 30% in the length direction of the tube due to its elasticity when pushed in with a force of 30 kPa applied from the outside. , the thickness of the base material is 3 mm or more.
Moreover, in order to solve the above-mentioned problem, this heat-insulating coating material for a heat-medium conduit may be a heat-insulating coating material for a heat-medium conduit that coats and keeps warm a copper or metal conduit that guides a heat medium.
Moreover, in order to solve the above-mentioned problem, the base material may have a structure in which closed cells and open cells are mixed.
In addition, in order to solve the above problem, in this thermal insulation coating material for a heat medium conduit, the outer surface of the base material is made of flame retardant or noncombustible material that can be expanded and contracted in the length direction according to the elastic expansion and contraction of the base material. can be covered with a sheet of
Moreover, in order to solve the above-mentioned problem, in this thermal insulation coating material for a heat transfer conduit, the base material can have a water absorption amount of 2 grams or less per 100 square centimeters.
Moreover, in order to solve the above-mentioned problem, in this thermal insulation coating material for a heat medium conduit, a plurality of pores whose thickness direction of the cylinder is the depth direction may be provided in a scattered manner in the base material.
In addition, in order to solve the above problems, in this thermal insulation coating material for heat medium conduits, the inner peripheral surface of the base material is covered with a heat-resistant sheet that has higher heat resistance than the base material. It may have a configuration that can be expanded and contracted in the length direction according to elastic expansion and contraction.
In addition, in order to solve the above problem, in this thermal insulation coating material for heat medium conduits, the base material is a plurality of rolled cylindrical sheets made of polyolefin resin foam with an expansion ratio of 35 times to 60 times. It may have a laminated structure consisting of layers.
In addition, in order to solve the above problems, the heat-insulating coating composite material for heat-medium conduits according to the disclosed invention includes a heat-insulating coating material for heat-medium conduits according to the disclosed invention, and a base material in this heat-insulating coating material for heat-medium conduits. This is a thermal insulation coating composite material for heat medium conduits, which is equipped with a low compressibility thermal insulation coating material, which is a cylindrical thermal insulation coating material that has lower compressibility than the base material. is fixed.
In addition, in order to solve the above problems, the insulation coating method according to the disclosed invention uses a cylindrical heat-retaining coating material that thermally insulates the periphery of each conduit when connecting conduits that guide a heat medium to form a conduit system. This method uses a first heat-insulating covering material with low compressibility and a second heat-insulating covering material with high compressibility as heat-insulating covering materials.
In this insulating coating method, the second heat-retaining coating material is a compressible coating material that can be compressed by 30% or more in length ratio with a force of 30 kPa in the longitudinal direction.
In this insulation coating method, the second insulation coating is compressed in the length direction by 30% or more in terms of length ratio and is sandwiched between two first insulation coatings, so that the second insulation coating has elasticity. In this method, construction is completed with the first heat-insulating covering material on both sides pressed.

As explained below, according to the thermal insulation coating material for a heat medium conduit according to the disclosed invention, when a force of 30 kPa is applied from the outside and pushed in, the elasticity increases the length ratio in the length direction of the tube by 30% or more. Since it is compressible, the problem of heat shrinkage of the thermal insulation covering material can be effectively solved by completing the construction in a compressed state. That is, when thermal contraction occurs in the low-elastic heat-insulating coating, the heat-transfer conduit heat-insulating coating expands (expands) due to its elasticity and eliminates the tensile pressure at the interface with the low-elastic heat-insulating coating. Therefore, separation or breakage does not occur at the connection point with the low-elastic heat-insulating covering material. This prevents dew condensation from occurring due to deterioration of thermal insulation at this location.
In addition, if the outer surface of the base material is covered with a flame-retardant or non-combustible sheet, there is no need for the base material itself to be flame-retardant or non-combustible, giving greater freedom in material selection. It increases.
In addition, according to the structure in which the base material is provided with a plurality of pores scattered in the thickness direction of the cylinder, it is possible to easily obtain a base material having desired compressibility. It is suitable for
Moreover, according to the structure in which the inner circumferential surface of the base material is covered with a heat-resistant sheet, there is no need to increase the heat resistance of the base material itself, which increases the degree of freedom in material selection.
Further, when the base material has a laminated structure consisting of a plurality of layers formed by rolling a sheet made of polyolefin resin foam into a cylindrical shape, it is possible to easily obtain a thick base material as a whole.
Further, according to the thermal insulation coating composite material for heat medium conduits according to the disclosed invention, the cylindrical thermal insulation coating material, which has lower compressibility than the base material in the thermal insulation coating material for heat medium conduits, is provided on both end surfaces of the base material. Because it is fixed in place, it is possible to prevent construction errors such as fixing the thermal insulation coating material for heat transfer pipes in a compressed state with a low-compressibility thermal insulation coating material and adhesive tape, and there is no need to pay attention to the timing of fixation. Effects can be obtained. In addition, the adhesive tape used to fix low-compressibility heat-insulating coatings to each other is not suitable for fixing heat-transfer conduit heat-insulating coatings and low-compressible heat-insulating coatings, and a different adhesive tape is used. Even when used, there is no need to prepare another adhesive tape at the time of construction, which has the effect of eliminating complexity.
Further, according to the insulation coating method according to the disclosed invention, the second heat insulation coating material is compressed in the length direction by 30% or more in terms of length ratio and is sandwiched between two first heat insulation coating materials, Due to the elasticity of the second insulation coating, construction is completed when it is pressed against the first insulation coating on both sides, so if heat shrinkage occurs in the first insulation coating, the second insulation coating will In response, it expands (stretches) due to its elasticity. Therefore, there is no gap between the first heat-insulating covering material and the second heat-insulating covering material. This prevents dew condensation from occurring due to deterioration of thermal insulation at this location.

It is a perspective schematic diagram of the thermal insulation covering material for heat medium conduits of embodiment. FIG. 2 is a schematic cross-sectional view of a heat-retaining coating material for a heat medium conduit according to an embodiment. FIG. 2 is a schematic diagram showing the compressibility of the heat-retaining coating material for a heat medium conduit according to an embodiment. It is a perspective schematic diagram of the base material in embodiment. It is a diagram showing the formation position of each pore, and is a schematic perspective view of a sheet-like semi-finished product. It is a schematic diagram of the insulation coating method using the thermal insulation coating material for heat medium conduits of embodiment. FIG. 3 is a schematic diagram showing fixation using adhesive tape. FIG. 2 is a schematic diagram of a thermal insulation coating composite material for a heat medium conduit according to an embodiment. FIG. 2 is a schematic diagram showing a conventional insulation coating method when forming a conduit system.

Next, a mode (embodiment) for carrying out the invention of this application will be described.
FIG. 1 is a schematic perspective view of a heat-insulating coating for a heat-medium conduit according to an embodiment, and FIG. 2 is a schematic cross-sectional view of the heat-insulating coating for a heat-medium conduit according to the embodiment. The thermal insulation coating material for a heat medium conduit of the embodiment is a member that covers and thermally insulates the periphery of a conduit that guides a heat medium, and is highly compressible so that it can be greatly contracted by external force. Hereinafter, this thermal insulation coating material for heat medium conduits will be referred to as a high compression material. As shown in FIGS. 1 and 2, the highly compressible material of the embodiment has a cylindrical shape.
As shown in FIGS. 1 and 2, the high compression material of the embodiment includes a cylindrical base material 1, an exterior sheet 2 provided to cover the outer surface of the base material 1, and an inner surface of the base material 1. It consists of an interior sheet 3 that covers the circumferential surface, and has a three-layer structure.

A major feature of the highly compressible material of this embodiment is that it has much higher compressibility than conventional low compressible thermal covering materials. Specifically, when a force of 30 kPa is applied in the longitudinal direction of the cylinder, it can be compressed by 30% or more in terms of size ratio (length ratio). This feature is brought about by the base material 1, which can be compressed by 30% or more when a force of 30 kPa is applied in the length direction of the tube. The base material 1 is the main member constituting the highly compressible material, and therefore has a thickness that is thicker than half of the total thickness.
It should be noted that 30 kPa is based on the assumption that the average force is applied when an adult male holds and presses in his hand. In other words, being compressible by 30% or more under 30kPa means that when a worker presses a highly compressible material on site, it can be compressed by 30% or more.

FIG. 3 is a schematic diagram showing the compressibility of the highly compressible material of the embodiment.
As shown in FIG. 3, when the highly compressible material of the embodiment is pressed with a force F in the length direction, the cross-sectional area (area in a cross section perpendicular to the length direction) is compressed without substantially changing. Ru. Therefore, the compressibility of 30% or more at 30 kPa may be expressed as a size ratio (length ratio) or a volume ratio. The example in FIG. 3 shows the size ratio, and L2/L1 is 30% or more. Note that "the cross-sectional area does not substantially change" means that even if the cross-sectional area increases, the outer diameter (in the case of a bellows-like shape, the average value) increases by about 10%.
Further, as shown in FIG. 3, when the highly compressible material is compressed in the length direction, the exterior sheet 2 and the interior sheet 3 are thin, so they shrink in a wrinkled state. However, the exterior sheet 2 and interior sheet 3 also have some elasticity, and may shrink due to wrinkles as their volume decreases.

In this embodiment, the base material 1 having high compressibility as described above is made of polyolefin resin foam. A polyolefin resin foam is a foamed resin composition mainly composed of a polyolefin resin, and the polyolefin resin is a homopolymer or copolymer of an olefin hydrocarbon, For example, polyethylene, polypropylene, ethylene-propylene copolymer, copolymer of ethylene and α-olefin such as butene or pentene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester Examples include copolymers, ethylene-styrene copolymers, ethylene-propylene-styrene-butadiene copolymers, ethylene-vinyl chloride copolymers, and mixtures of two or more of these. These olefin resins may be chemically modified such as grafting. In addition, the polyolefin resin foam may contain other thermoplastic resins such as thermoplastic elastomers, antioxidants, lubricants, colorants, and deodorants, as necessary, within a range not exceeding 50% by mass of the resin composition. , antistatic agents, flame retardants, and other various additives can be added.

High compressibility, which is a major feature of the highly compressible material of the embodiment, is achieved by appropriately selecting the expansion ratio. Specifically, in the highly compressible material of the embodiment, the expansion ratio of the polyolefin resin foam forming the base material 1 is appropriately selected within the range of 35 times or more and 60 times or less. If the expansion ratio is less than 35 times, the necessary compressibility cannot be obtained. If it exceeds 60 times, the compressibility is good, but the apparent density decreases, making it impossible to obtain the necessary strength. Expressed as an apparent density, the apparent density of the base material 1 is preferably 16 to 28 kg/m ³ . The apparent density here is a value measured by a method according to JIS K 6767. Note that methods for obtaining the base material 1 made of polyolefin resin foam with an expansion ratio of 35 to 60 times include a method using pre-expanded particles as disclosed in International Publication No. 2015/133619 (Patent Document 3); , a method of foaming using the action of carbon dioxide gas generated by decomposition of sodium hydrogen carbonate as disclosed in JP 2012-97285 A (Patent Document 4), International Publication No. 2019/073873 (Patent Document 5) A foaming method using gas generated by decomposition of azodicarbonamide as disclosed may be employed.

The base material 1 mainly composed of a polyolefin resin foam having an expansion ratio of 35 to 60 times preferably has a structure in which closed cells and open cells are mixed. If it is made of 100% closed cells, the repulsion force when compressed is strong and construction is difficult. Furthermore, if the cell is 100% open cells, it is good in terms of compressibility, but it tends to absorb moisture and may cause a decrease in heat insulation performance.

Moreover, as a characteristic of the member constituting the heat-retaining coating material for a heat medium conduit, it is preferable that the base material 1 has a water absorption amount of 2 g/100 cm ² or less. The water absorption amount of the base material 1 can be measured by a method according to the method specified in JIS A 9511. If the amount of water absorption exceeds 2 g/100 cm ² , there may be a problem that the insulation performance is deteriorated due to the moisture occluded during dew condensation, and a problem that water droplets are likely to fall due to the accumulation of a large amount of moisture may occur.

As a method for obtaining the base material 1 while adjusting the foaming ratio so as to have appropriate compressibility and mechanical strength while having a mixture of closed cells and open cells, an appropriate foaming method from among physical or chemical foaming methods can be used. A method can be used in which a closed-cell foam with an arbitrary expansion ratio is made using a method, and then a part of the cell membrane is destroyed to form open cells. Physical foaming methods for obtaining closed-cell foams include, for example, extrusion foaming, in which gas or vaporized solvent is melted in an extruder and foamed while extruded under high pressure, and resin particles containing gas or vaporized solvent are foamed. Solvent aeration methods such as a bead foaming method in which the resin is pre-foamed and then foamed and fused in a mold, and a gas impregnation method in which a gas is dissolved in a resin in a high-pressure container and foamed by heating at normal pressure can be used. Chemical foaming methods include the normal pressure foaming method, in which resin and a pyrolytic chemical foaming agent are melted and kneaded and foamed under normal pressure heating, and the pyrolytic chemical foaming agent is heated and decomposed in an extruder under high pressure. Foaming agent decomposition methods can be used, such as an extrusion foaming method in which the foam is foamed while being extruded, and a press foaming method in which a thermally decomposable chemical foaming agent is thermally decomposed in a press mold and foamed while being depressurized. Among these, the blowing agent decomposition method is more suitable since it is easy to keep the size of the bubbles small. Further, as a method of partially destroying the cell membrane to form open cells, for example, a method of passing the foam between two rolls and subjecting it to compressive deformation can be used.

Furthermore, the highly compressible material of the embodiment has a two-layer structure as shown in FIG. It is formed of an inner first layer 11 and an outer second layer 12. Each layer 11, 12 is the same polyolefin resin foam. The fact that the base material 1 has a two-layer structure is suitable for obtaining a thick base material 1 as a whole.

In many cases, the base material 1 is made into a cylindrical shape by cutting a wide elongated sheet-like foam (hereinafter referred to as a sheet-like semi-finished product) to a width matching the diameter of a pipe for heat insulation and rolling it up. After heating the sheet-like semi-finished product to a temperature that makes it easy to shape it, it is rolled up using a jig, and the end faces are heat-sealed to form a cylindrical shape. At this time, if a sheet-like semi-finished product with the final required wall thickness is used, it is possible to obtain the base material 1 with a single layer structure, but if the wall thickness is thick when rolling it into a cylindrical shape, there will be a difference between the inner and outer circumferences. It becomes larger and cannot be fused on the outer circumferential side of the end face, creating a gap, which deteriorates the heat insulation performance. In order to obtain a base material 1 whose end surfaces are sufficiently fused over the entire thickness, the thickness of the sheet-like semi-finished product is preferably 3 to 15 mm. On the other hand, this level of thickness is often insufficient for a highly compressible material to exhibit sufficient thermal insulation function, and it is necessary to adjust the thickness to the specified thickness for each final product. It is preferable to have a multilayer structure of more than one layer.

Further, the multilayer structure may also be used for the purpose of adjusting the overall thickness of the base material 1. When only several thicknesses of semi-finished sheet products can be obtained, the base material 1 of an appropriate thickness may be obtained by appropriately combining them. In addition, the base material 1 may have three or more layers, including the case of adjusting the thickness. Furthermore, in the case of a multilayer structure, the interface between each layer is usually fused by heat during lamination.

FIG. 4 is a schematic perspective view of the base material in the embodiment. As shown in FIG. 4, the base material 1 is provided with a plurality of pores 13 scattered therein. The pores 13 are provided for the purpose of promoting ventilation of air contained in the open cells of the base material 1 and adjusting the compressibility of the base material 1. Each pore 13 is provided so that the thickness direction of the base material 1 is the depth direction.

Each pore 13 has a depth that does not reach the thickness of the entire base material 1 and does not penetrate through the base material 1. In this embodiment, each pore 13 has a depth corresponding to the thickness of each layer 11,12. That is, the pores 13 in the first layer 11 penetrate the first layer 11, but terminate at the interface (fused portion) with the second layer 12. Similarly, each pore 13 in the second layer 12 has a depth equivalent to the thickness of the second layer 12, but terminates at the interface with the first layer 11.
If each of the pores 13 penetrates through the entire thickness of the base material 1, there is a problem that not only the thermal insulation property is deteriorated, but also that it becomes a path for water droplets to flow and fall during dew condensation. Therefore, each pore 13 preferably has a structure that does not penetrate through the entire thickness of the base material 1. As long as it does not penetrate, it may be, for example, half the depth in layers 11 and 12.

Such pores 13 can be formed using a jig such as a sword mount provided with needles at predetermined equal intervals. For example, the pores 13 are formed in a sheet-like semi-finished product at room temperature using a jig. Thereafter, the first layer 11 is formed by rolling it up and heat-sealing the end face, and then repeating the same process to cover the first layer 11 with the second layer 12 provided with pores 13 and rolling it up, heat-sealing the end face. wear it.
The pores 13 may be formed only in the first layer 11 or may be formed only in the second layer 12. When forming only the second layer 12, the second layer 12 may be placed on the first layer 11 and rolled up, and then a jig may be applied to the surface (outer surface) to form each pore 13.

FIG. 5 is a diagram showing the formation position of each pore 13, and is a schematic perspective view of a sheet-like semi-finished product. As shown in FIG. 3, in the sheet-like semi-finished product 14, the pores 13 are arranged in a so-called zigzag pattern, and the pores 13 are arranged so that an imaginary line connecting three adjacent pores 13 forms an equilateral triangle. . In this example, one side of the equilateral triangle is the formation interval d of the pores 13. FIG. 3 is an example of an example of uniform arrangement spacing of the pores 13, and the spacing d is preferably 10 to 50 mm. When it is shorter than 10 mm, the number of pores 13 increases, the mechanical strength decreases, and the problem of breakage may occur. If it is longer than 50 mm, there may arise a problem that the effect of adjusting compressibility cannot be sufficiently obtained. There may be various arrangement patterns other than the example shown in FIG. 5. The upper and lower limits of the distance d may be the shortest distance between adjacent pores 13 in each arrangement pattern.

Further, the cross-sectional area (area in a plane perpendicular to the depth direction) of each pore 13 is preferably about 0.1 to 5 mm ² . When the cross-sectional shape of each pore 13 is considered circular, the equivalent circular diameter is approximately 0.4 to 2.5 mm. If the cross-sectional area of the pores 13 is smaller than 0.1 mm ² , there may arise a problem that the effect of adjusting compressibility cannot be sufficiently obtained. If it is larger than 5 mm ² , a problem may arise in which the thermal insulation performance deteriorates.

Note that the polyolefin resin foam that is the material of the base material 1 is desirably crosslinked. Although the base material 1 in the embodiment can be obtained by foaming a non-crosslinked polyolefin resin, problems may arise in that the bubble diameter is large and the heat resistance is low. A polyolefin resin foam crosslinked by a conventionally known method such as crosslinking with an electron beam or peroxide can be suitably used as the material for the base material 1. For example, a method may be adopted in which a blowing agent is kneaded into a polyolefin resin, molded into a sheet, crosslinked by electron beam irradiation, and further heated and foamed to obtain a sheet-like semi-finished product.

On the other hand, the exterior sheet 2 is a flame-retardant or non-flammable (hereinafter generically referred to as the term flame-retardant and non-flammable) sheet, and is provided for the purpose of imparting flame-retardant and non-flammable properties to the highly compressible material. As the flame-retardant and non-flammable sheet, it can be used without particular restrictions as long as it has the necessary flame-retardancy and is flexible enough to wrinkle as the base material 1 is compressed. . For example, flame-resistant nonwoven fabrics using oxidized acrylic fibers are sold by various companies, and can be appropriately selected and used.
The thicker the exterior sheet 2 is, the better the flame retardancy is, but since it may impede the compressibility of the base material 1, a thickness of 1.5 mm or less is preferably used. The fixation to the outer surface of the base material 1 is often done by adhesive (the exterior sheet 2 is an adhesive sheet or another adhesive sheet is used), but it may also be done by heat fusion or ultrasonic welding.

The interior sheet 3 is provided in consideration of the heat resistance of the base material 1. The base material 1 is characterized by high compressibility as described above, and has a high foaming ratio to achieve high compressibility. Heat resistance is often lower than that of compressed materials. For this reason, in the case of conduit systems in heating equipment, boilers, etc. in which a high-temperature heat medium flows, if heat from the conduit is applied directly to the base material 1, the temperature of the base material 1 will rise beyond its heat-resistant temperature. It may become soft and deformed. Taking this into consideration, the interior sheet 3 is provided. Therefore, the interior sheet 3 is a highly heat-resistant material containing a resin having a melting point higher than the temperature of the conduit. For example, a sheet made of a polyolefin resin foam containing a thermoplastic elastomer as disclosed in International Publication No. 2019/073873 (Patent Document 5) can be used as the interior sheet 3. The thickness of the interior sheet 3 is preferably 0.5 mm or more and 3 mm or less. If it is less than 0.5 mm, the heat insulation performance may be insufficient and heat may be transferred to the base material 1, and if it is thicker than 3 mm, the compressibility of the base material 1 is likely to be inhibited.

Next, a method of insulating a conduit system using the highly compressible material of this embodiment will be described. The following description is also a description of inventive embodiments of the insulation coating method.
FIG. 6 is a schematic diagram of an insulation coating method using the highly compressible material of the embodiment. This insulation coating method is performed when connecting conduits to form a conduit system.

Taking as an example the case where a conduit system is formed using the conventional conduit unit 4 described above, the conduit unit 4 includes a conduit 41 having a length determined by the standard, and a conduit system provided to cover the circumferential surface of the conduit 41. It consists of a heat insulation covering material 42. Therefore, in this example, the heat insulation coating 42 in the conduit unit 4 corresponds to the first heat insulation coating with low compressibility, and the high compression material 10 of the embodiment corresponds to the second heat insulation coating with high compressibility. It is equivalent. Hereinafter, for the sake of distinction, the heat-insulating covering material 4 in the conduit unit 4 will be referred to as a commonly available covering material. In this example, in the conduit unit 4, the conduit 41 and the commonly available covering material 42 have the same length.

In this insulation coating method, the conduit system formed is a place where the highly compressible material 10 compressed by pressure receives the force (restoring force) of the highly compressible material 10 trying to return to its original state due to elasticity, and maintains the compressed state of the highly compressible material 10. will be provided in at least two locations. This location is a location that causes a reaction to the restoring force of the highly compressible material 10, and is hereinafter referred to as a reaction location. Reaction points are typically bends in the conduit system.

When forming a conduit system, a necessary number of conduit units 4 are prepared, the conduits 41 are connected to each other by welding or the like, and the conduits 41 are extended along a desired route. At this time, the commonly available covering materials 42 are also fixed to each other by wrapping a heat insulating adhesive tape (not shown in FIG. 6) around the connecting portions. Incidentally, the bent portion as a reaction point is formed by connecting the conduits to each other via a corner joint (usually bent at 90 degrees) having a shape corresponding to the bending. Hereinafter, it is assumed that a first bent part and a second bent part are formed as two reaction points.

As shown in FIG. 6(1), in the connection work of the conduit unit 4 after forming the first bent portion 51, the work of interposing the highly compressible material 10 of the embodiment is performed. That is, as shown in FIG. 6(1), for the conduit unit 4 with one side unconnected, the commonly available covering material 42 is slightly cut to expose the conduit 41. The exposed length of the conduit 41 is shorter than the total length L1 of the highly compressible material 10 in a free state, and is, for example, half the length L1.

Next, the highly compressible material 10 is attached to the exposed end of the conduit 41. That is, the end of the conduit 41 is inserted into the highly compressible material 10, and the highly compressible material 10 is attached. The inner diameter of the highly compressible material 10 (the inner diameter of the interior sheet 3) is slightly smaller than the outer diameter of the conduit 41, and the highly compressible material 10 covers the conduit 41 in a state in which it is in close contact with the conduit 41 due to its elasticity.
Next, the operator manually pushes and compresses the attached highly compressible material 10 in the length direction to expose the end of the conduit 41 again. At this time, the highly compressible material 10 is in a state of pressing the commonly available covering material 42. Note that each commonly used sheathing material 42 in each connected conduit unit 4 is also pressed one after another, but since the first bent part 51 exists as shown in FIG. It becomes a form of receiving (reaction).

Then, as shown in FIG. 6(2), while holding the highly compressible material 10 in a compressed state by manually pushing it in, the conduit 41 of another conduit unit 4 is welded to the exposed end of the conduit 41. Connect by. After that, when the hand is released, the highly compressible material 10 returns to its original length due to its elasticity. Next, as shown in FIG. 6(3), the commonly available covering material 42 of another conduit unit 4 is brought into contact with the highly compressible material 10. The commonly available covering materials 42 on both sides of the highly compressible material 10 are fixed to the highly compressible material 10 while leaving the highly compressible material 10 in a free state. For example, as in the case of fixing the commonly available covering materials 42 to each other, a thermally insulating adhesive tape (not shown in FIG. 6) is wrapped around the connecting portion and fixed. The adhesive tape can be compressed in the length direction of the conduit 41 by being wrinkled.

Next, after compressing the highly compressible material 10 again, temporary fixing is performed to maintain a predetermined compressed state. That is, the commonly available covering material 42 of another conduit unit 4 is grabbed and pushed toward the highly compressible material 10, thereby compressing the highly compressible material 10 to a predetermined length. Then, while maintaining this state, the popular covering materials 42 on both sides are temporarily fixed with temporary fixing tape 8 as shown in FIG. 6(4). The temporary fixing tape 8 is an adhesive tape that has an adhesive strength strong enough to maintain the compressed state of the highly compressible material 10 against the elasticity of the highly compressible material 10, and can be peeled off by hand by the worker upon completion of construction. . A commercially available so-called curing tape can be used as the temporary fixing tape 8. As shown in FIG. 6(4), the temporary tape 8 is pasted so as to bridge between the commonly available covering materials 42 on both sides. Note that the adhesive tapes (not shown) that fixed the highly compressible material 10 and the commonly available covering materials 42 on both sides wrinkle and shrink as the highly compressible material 10 is compressed. Incidentally, temporary fixing using the temporary fixing tape 8 is performed at a plurality of locations in the circumferential direction, and the commonly available covering materials 42 are fixed to each other at a plurality of locations.

After that, connection work for yet another conduit unit 4 is performed. That is, as shown in FIG. 6(4), when the compressed state of the highly compressible material 10 is maintained with the temporary fixing tape 8, the conduit 41 is exposed at the end of another conduit unit 4. On the other hand, as shown in FIG. 6(4), the conduit 41 of yet another conduit unit 4 is connected by welding or the like. Then, the commonly available covering materials 42 are joined together and similarly fixed with adhesive tape (not shown). As a result, as shown in FIG. 6(5), the connection points between the conduits 41 are covered with the commonly available covering material 42 of another conduit unit 4. At this time as well, the highly compressible material 10 is maintained in a compressed state by the temporary fixing tape 8.

In this way, the conduit units 4 are sequentially connected to extend the conduit system while compressing the highly compressible material 10 as appropriate and maintaining the compressed state with the temporary fixing tape 8, as shown in FIG. 6 (6). A second bent portion 52 is formed. The second bent portion 52 is similarly formed using the corner joint 50, and is bent at 90 degrees. At this time, as shown in FIG. 6(6), the end of the conduit 41 is exposed by appropriately cutting the commonly available covering material 42, and the corner joint 50 is connected to the exposed end by a method such as welding. .

The corner joint 50 is also covered with a special covering material, thereby forming a second bent portion 52. As a result, each temporary fixing tape 8 becomes unnecessary, so each temporary fixing tape 8 is peeled off. Each high compression material 10 tries to return to its original length due to its elasticity, but the first bending section 51 and the second bending section 52 act as reaction parts and absorb this restoring force, so that each high compression material 10 The state of being compressed to a predetermined length continues to be maintained.

In this way, each conduit unit 4 is connected with the highly compressible material 10 interposed as appropriate, and the restoring force of the highly compressible material 10 is received by the bent parts 51 and 52 as reaction parts, so that the compressed state of the highly compressible material 10 is , and form a conduit system along the desired route as shown in FIG. 6(7). When the conduit unit 4 is connected to the end of the desired route, the construction of the conduit system is completed.

As can be seen from the above description, in the completed construction state, each highly compressible material 10 is in a compressed state and elastically presses the commonly available covering material 42 on both sides in the length direction. This point is significant in effectively solving the problem of thermal shrinkage of the commonly available covering material 42. That is, since the highly compressible material 10 is in a state where the commonly available covering material 42 is constantly pressed, when the commonly available covering material 42 undergoes thermal contraction, the highly compressible material 10 elastically expands (expands) accordingly. To eliminate tensile pressure at the interface between the popular covering material 42 and the highly compressible material 10. Therefore, a gap is not formed between the commonly available covering material 42 and the highly compressible material 10, and the commonly available covering material 42 and the highly compressible material 10 do not break. Therefore, the thermal insulation at this location will not deteriorate and condensation will not occur.
Note that in the above example, the first heat-insulating covering material was the commonly used covering material 42, but it is sufficient that the first heat-insulating covering material has a lower compressibility than the highly compressible material 10. , materials other than the commonly available covering material 42 may be used.

The length, compression ratio, number of materials used, etc. of the highly compressible material 10 are appropriately determined depending on the amount of thermal contraction of the commonly available covering material 42 in the conduit system. The amount of thermal contraction of the commonly available covering material 42 is a value that depends on the temperature of the refrigerant flowing in the conduit 41, the thermal characteristics of the commonly available covering material 42, and the like. For example, if the popular sheathing material 42 is heated by the heat medium flowing in the conduit 41 and can undergo a heat contraction of 2% in terms of length, then a 4 m long popular sheathing material 42 will experience a thermal contraction of 80 mm. . Then, for example, if one high compression material 10 is interposed for every two commonly used covering materials 42, one high compression material 10 will need to compensate for 160 mm of thermal contraction, and this length will be reduced at the time of completion of construction. You just need to compress it. In this case, the actual compression amount is set to be a little larger than the required thermal shrinkage compensation amount, for example, 180 mm. For example, when using a highly compressible material 10 that can be compressed by a maximum of 50% and the actual compression amount is 30%, the length of 30% is 180 mm, so the free state of one highly compressible material 10 The length will be 600mm. That is, it is sufficient to provide one highly compressible material 10 with a length of 600 mm for every two commonly available covering materials 42 (every 8 m), and compress each member by 30% (180 mm).

What is important in the insulation coating method of the above embodiment is that when fixing the highly compressible material 10 to the commonly available covering material 42 using adhesive tape, the fixing with the adhesive tape is performed after the highly compressible material 10 is attached and before being compressed. It is a good idea to keep it. This point will be explained with reference to FIG. FIG. 7 is a schematic diagram showing fixation using adhesive tape. In FIG. 7, a part of the adhesive tape is shown by a cross section and a virtual line.

Regarding the insulation coating method of the embodiment, as shown in FIG. 7(A), the highly compressible material 10 is pushed into a compressed state, and in this state, an adhesive tape 43 is wrapped around the interface with the commonly available covering material 42 to fix it. It is possible to do so. Although this method can be implemented, the adhesive tape 43 prevents the highly compressible material 10 from expanding in response to the accompanying tensile force when the popular covering material 42 heat-shrinks after construction. Become. If the tensile force (restoring force) of the highly compressible material 10 is large, the adhesive tape 43 may break.

On the other hand, as shown in FIG. 7(B), if the highly compressible material 10 is in a free state and is fixed with the popular covering material 42 and the adhesive tape 43, when the highly compressible material 10 is pushed in and compressed. The adhesive tape 43 wrinkles and shrinks due to its flexibility (the wrinkles form as if tracing the irregularities on the outer surface of the highly compressible material 10). For this reason, when the popular covering material 42 heat-shrinks after construction, the adhesive tape 43 stretches to smooth out wrinkles in accordance with the stretch of the highly compressible material 10, so it does not impede the stretch of the highly compressible material 10. Therefore, the adhesive tape 43 does not break.

In addition, also in the case of FIG. 7(A), if an elastic adhesive tape is used, the expansion of the highly compressible material 10 can be prevented. However, if the amount of elongation of the highly compressible material 10 is large and the elongation of the adhesive tape cannot keep up, a similar problem may occur. In addition, elastically stretchable adhesive tapes often have low fixing strength, tensile strength, etc., and are inferior in terms of reliability in fixing the highly compressible material 10 and the commonly available covering material 42.

Next, an embodiment of the invention of a thermal insulation coating composite material for a heat medium conduit will be described.
FIG. 8 is a schematic diagram of a thermal insulation coating composite material for a heat medium conduit according to an embodiment. The thermal insulation coating composite material for a heat medium conduit (hereinafter abbreviated as composite material) of the embodiment is a thermal insulation coating material composited using the highly compressible material of the embodiment described above. Specifically, it is a coating material that is a composite of the highly compressible material 10 of the above embodiment and the cylindrical heat-insulating covering material 6 whose compressibility is lower than that of the base material 1 in the highly compressible material 10. "Low compressibility" means that the amount of compression is small when the same external force is applied. Hereinafter, the thermal covering material 6 with low compressibility will be referred to as a low compression material.

As the low compression material 6, in this embodiment, a commonly used covering material is cut and used. Since the standard and popular heat insulation covering material has a length of 4 meters, the low compression material 6 is cut into a length of about 30 cm, for example.
As shown in FIG. 8, the composite material has a structure in which two low compression materials 6 having approximately the same outer diameter as the high compression materials 10 are used, and the low compression materials 6 are extended to both ends of the high compression materials 10. ing. The inner diameter of the low compression material 6 is approximately the same as that of the high compression material 10, and is slightly smaller than the outer diameter of the conduit to be covered. Since it is similar to a popular product, the low compression material 6 is made of a polyolefin resin foam such as a low-expansion polyethylene resin foam.

As shown in FIG. 8, the composite material of the embodiment has a fixing part 7 to which a high compression material 10 and a low compression material 6 are fixed. Although the fixing part 7 is an adhesive tape 43 in the example of FIG. 8, other embodiments are also possible. That is, it may be fixed by adhesive or by fusion. That is, the fixing part 7 may be an adhesive layer provided at the interface between the high compression material 10 and the low compression material 6, or it may be a fusion layer where the high compression material 10 and the low compression material 6 are fused together by heat or the like. could be.

The method of insulating a conduit system using the composite material of the embodiment can also be performed in the same manner as the method of the embodiment described above. Similarly, using a conduit unit as an example, the commonly available covering material is cut to a predetermined length at one end of the conduit unit to expose the end of the conduit. The predetermined length is the length of the composite material when the highly compressible material 10 is compressed, and the length of the composite material when the highly compressible material 10 is compressed is the length of the composite material when the highly compressible material 10 is compressed. It is determined in advance based on the installation interval of the composite material, the degree of heat shrinkage of the commonly available covering material, etc.

Then, a composite material is attached to the exposed end of the conduit, and the composite material is pressed to compress the highly compressible material 10, thereby exposing the end of the conduit again. Then, a conduit from another conduit unit is connected thereto by welding or the like. Next, the high compression material 10 in the composite material is compressed again by a predetermined length, and in order to maintain this state, the low compression materials 6 (or the commonly available covering materials in the conduit units on both sides) are temporarily fixed with tape. Fix it with. Then, another conduit unit is connected to another conduit unit, and the conduit units are successively connected at appropriate intervals while interposing the composite material. When the construction position of the second bending part as the second reaction part is reached, the corner joint is connected to the conduit and covered with a special covering material. As a result, a second bent portion is formed, and each temporary tape is no longer needed and is peeled off.

In the composite material of such an embodiment, the point that the high compression material 10 is provided as a composite material fixed in advance to the low compression material 6 has the following significance.
First, as described above, when the highly compressible material 10 is delivered as a single unit to the construction site, when fixing it to the commonly available covering material 42, the highly compressible material 10 is pushed in and compressed and fixed with adhesive tape. Otherwise, the above-mentioned problem will occur. Therefore, care must be taken in the construction procedure. As in the embodiment, when a composite material is provided in which the low-compression material 6 made of the same material as the popular covering material 42 is fixed in advance to both ends of the high-compression material 10, the fixing at the construction site is performed using the popular covering material 42. The only problem is the fixing of the covering material 42 and the low compression material 6, and there is no particular problem with the timing. Therefore, the construction procedure is not complicated in the sense that it requires careful attention.

Furthermore, depending on the material of the highly compressible material 10, in order to fix the highly compressible material 10 and the commonly available covering material 42, an adhesive tape different from the adhesive tape used for fixing the commonly available covering materials 42 to each other may be used. It may be necessary. In this case, adhesive tape for fixing the commonly available covering materials 42 to each other and adhesive tape for fixing the highly compressible material 10 and the commonly available covering material 42 must be prepared at the construction site, which is complicated. be. If used incorrectly, the fixation will be insufficient and accidents such as peeling of the joint may easily occur. This point is also complicated. According to the composite material of the embodiment, there is no such complication, and the thermal insulation coating of the conduit system using the highly compressible material 10 can be easily performed with high reliability.
Note that the low compression material 6 may have a double structure as appropriate. For example, the outer layer may have an embossed outer surface to make it easier to fix with adhesive tape, or the outer layer may be made of flame-retardant and non-flammable material. .

In each of the embodiments described above, the material of the base material 1 may be a polyolefin resin foam to which an elastomer is added as described above, but the base material 1 may be a member exhibiting so-called low resilience. Low resilience refers to, for example, a case where the resilience modulus is about 15% or less (JIS K 6400-3). When the base material 1 is a member that exhibits low resilience, the highly compressible material 10 as a whole is also a member that exhibits low resilience. Such a highly compressible material 10 has the advantage of being easy to work with because it does not return to its original state immediately when an operator attempts to work in a compressed state by pushing it during construction.

Although the cross-sectional area of the base material 1 does not substantially change when it is pushed and compressed, the cross-sectional area may become larger. For example, the cross-sectional area may increase by about 10 to 30%.
In each of the above embodiments, the highly compressible material 10 has a cylindrical shape, but it may also have a rectangular cylindrical shape. Depending on the shape of the piping, the inner circumferential surface may be shaped like a tube, or the outer circumferential surface may be shaped like a rectangular tube.

Furthermore, if the base material 1 is flame retardant, the exterior sheet 2 may not be provided, and if the base material 1 has high heat resistance, the interior sheet 3 may not be provided. . Regarding the expansion and contraction of the exterior sheet 2 and the interior sheet 3 that occur with the expansion and contraction of the base material 1, it is desirable that the expansion and contraction occur due to wrinkles or the elongation of wrinkles, but expansion and contraction due to elasticity may also be used.
In addition to the above-mentioned bent parts 51 and 52, reaction parts include walls when the conduit system is constructed through the wall, and various equipment (air conditioners, refrigerators, etc.) as the terminal ends of the conduit system. It is also possible that the casing etc.

Toray Pef 50100AY0B (closed cell, expansion ratio 50 times, thickness 10 mm) manufactured by Toray Industries, Inc. was used as a long sheet made of polyolefin resin foam, and the long sheet was passed through a roll equipped with needles at 20 mm intervals in a staggered manner. Pores were made in the sheet, and then the foam was passed between two rolls with a gap of 0.1 mm, compressing and deforming the foam to partially destroy the cell membrane, resulting in a structure with a mixture of closed cells and open cells. A long sheet of polyolefin resin foam was obtained.
The obtained long sheets were cut into widths of 126 mm (sheet A) and 210 mm (sheet B). Sheet A was passed through a conical guide with an exit inner diameter of 40 mm and rolled into a cylindrical shape, and the end surfaces of sheet A were heat-sealed to form a cylindrical shape. Further, the sheet B is placed around it and passed through a conical guide with an exit inner diameter of 62 mm, and the cylindrical sheets A and B are thermally fused by blowing hot air into the guide. A base material 1 having a two-layer structure was obtained by heat-sealing the end surfaces of B. When the obtained base material 1 was subjected to an external force of 30 kPa in the length direction of the cylinder, the compression in terms of length ratio was 63%. Moreover, the water absorption amount was 1.1 g/100 cm ² .

1 Base material 10 High compression material 2 Exterior sheet 3 Interior sheet 4 Conduit unit 41 Conduit 42 Low compressibility insulation coating 51 First bent part 52 Second bent part 6 Low compression material 7 Fixed part 8 Temporary fixing tape

Claims (10)

A thermal insulation coating material for a cylindrical heat medium conduit that coats and insulates a conduit guiding a heat medium on the outside , and includes a base material made of a polyolefin resin foam having an expansion ratio of 35 times or more and 60 times or less. Ori,
The base material (excluding those with air bubbles exposed on the outer surface by slicing) has a wall thickness that is more than half of the total wall thickness,
It has a compressibility that allows it to be compressed by more than 30% in the longitudinal direction of the cylinder due to its elasticity when pushed in by applying a force of 30kPa from the outside.
A heat-insulating coating material for a heat medium conduit, characterized in that the thickness of the base material is 3 mm or more. 2. The heat-insulating coating material for a heat-medium conduit according to claim 1, which is a heat-insulating coating material for a heat-medium conduit that coats and insulates a copper or metal conduit that guides a heat medium. The thermal insulation coating material for a heat medium conduit according to claim 1 or 2, wherein the base material has a structure in which closed cells and open cells are mixed. 4. The outer surface of the base material is covered with a flame-retardant or non-combustible sheet that can be expanded and contracted in the longitudinal direction according to elastic expansion and contraction of the base material. Thermal insulation coating material for heat medium conduits described in the above. The thermal insulation coating material for a heat medium conduit according to any one of claims 1 to 4, wherein the base material has a water absorption amount of 2 grams or less per 100 square centimeters. The thermal insulation coating for a heat medium conduit according to any one of claims 1 to 5, wherein the base material is provided with a plurality of pores scattered in the thickness direction of the cylinder. Material. The inner circumferential surface of the base material is covered with a heat-resistant sheet having higher heat resistance than the base material, and the heat-resistant sheet is expandable and contractible in the length direction according to the elasticity of the base material. The thermal insulation coating material for a heat medium conduit according to any one of claims 1 to 6, characterized in that: A claim characterized in that the base material has a laminated structure consisting of a plurality of layers formed by rolling a sheet made of a polyolefin resin foam having an expansion ratio of 35 times or more and 60 times or less into a cylindrical shape. Item 8. The thermal insulation coating material for a heat medium conduit according to any one of Items 1 to 7. The thermal insulation coating for a heat medium conduit according to any one of claims 1 to 8, and a low compressibility thermal insulation coating that is a cylindrical thermal insulation coating having lower compressibility than the base material in the thermal insulation coating for a heat medium conduit. A thermal insulation coating composite material for a heating medium conduit, characterized in that the low compressibility thermal insulation coating material is fixed to both end faces of the base material. . An insulating coating method in which when conduits that guide a heat medium are connected to form a conduit system, the periphery of each conduit is covered with a cylindrical heat-insulating coating material that thermally insulates the conduit, the method comprising:
A method of using a first heat-insulating covering material with low compressibility and a second heat-insulating covering material with high compressibility as the heat-insulating covering material,
The second heat-retaining covering material is a compressible covering material that can be compressed by 30% or more in length ratio with a force of 30 kPa in the length direction,
The second heat-insulating covering material is compressed by 30% or more in the length direction and is sandwiched between the two first heat-insulating covering materials, and the second heat-insulating covering material is elastically compressed to cover the first heat-insulating material on both sides. An insulation coating method characterized by completing construction with the coating material pressed.

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