Condensation water dropping-preventive heat insulator, condensation water dropping-preventive refrigerant piping and piping structure for water and hot-water supply using the same, and structure for condensation water dropping-preventive building, condensation water dropping-preventive nonwoven fabric, and method for forming condensation water dropping-preventive structure for refrigerant piping using the heat insulator and method for forming condensation water dropping-preventive structure for building member

Abstract

To provide a structure of a nonwoven fabric for condensation water dropping prevention, a heat insulator using the same, and its applications to a piping structure and a building structure.SOLUTION: A condensation water dropping-preventive heat insulator 3 has a nonwoven fabric 8 disposed on at least one surface of a polyethylene resin foam 7. The constituent fibers of the nonwoven fabric are at least partially fused or bonded to the surface of the polyethylene resin foam. The fiber has an average fiber diameter of 10-30 μm, the fiber has a voidage of 85-98%, and a 5% tensile stress value is 25 MPa or less and 1 MPa or more.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an insulating material for preventing condensation from dripping, a refrigerant piping and water supply / hot water piping structure using the same for preventing condensation from dripping, a building structure for preventing condensation from dripping, a nonwoven fabric for preventing condensation from dripping, a method for forming a condensation from dripping structure for refrigerant piping using the insulating material, and a method for forming a condensation from dripping structure for building components. [Background technology]

[0002] Conventionally, a material was used as insulation for refrigerant piping in air conditioning equipment, which consisted of polyethylene foam laminated with polyethylene or polypropylene film on at least one surface, and then embossed on the surface of the laminated resin foam. However, with such insulation, condensation formed on the surface of the insulation used around the refrigerant piping, and this condensed water dripped into piping spaces in the ceiling, causing mold to grow in those spaces.

[0003] Patent Document 1 describes a duct in which a nonwoven fabric is integrally molded into the duct body. In this duct, a nonwoven fabric is integrally molded into the duct body, and the duct body is a foam blow molded body. Because the nonwoven fabric is integrally molded into the duct body, which is a foam blow molded body, condensation is less likely to occur on the surface of the duct body, and even if condensation occurs, the condensed water is absorbed by the nonwoven fabric, so the dripping of condensed water is suppressed.

[0004] The invention described in Patent Document 1 has a nonwoven fabric integrally molded into the duct body, which prevents the nonwoven fabric from peeling off the duct body. Since the nonwoven fabric is integrally molded into the duct body, it is not a matter of heat-sealing the foam and the nonwoven fabric.

[0005] Patent Document 2 describes a segmented air conditioning duct consisting of an inner layer made of a closed-cell foam and a nonwoven fabric made of thermoplastic resin. In this segmented duct, the outer layer contains two types of thermoplastic resins with different melting points, and the resin layers with lower melting points are bonded to each other by fusion. Furthermore, the segmented air conditioning duct is formed by bonding the foam of the inner layer and the outer layer with a hot-melt adhesive that can bond at a temperature lower than the melting point of the lower-melting-point fiber of the two types of fibers forming the outer layer.

[0006] Furthermore, this application states that the foam can be made of thermoplastic resin foam such as polyethylene or polypropylene, or polyurethane foam, and that the nonwoven fabric can be made of thermoplastic resin fibers such as polyethylene, polypropylene, or polyethylene terephthalate, and that a core-sheath structure can be formed using resins with different melting points.

[0007] This application describes a nonwoven fabric that is a multilayer nonwoven fabric having a core-sheath structure using two types of fibers, and further describes a foam layer and a nonwoven fabric being bonded together with a hot-melt adhesive.

[0008] Patent Document 3 discloses a heat-insulating material characterized by a laminated porous film and nonwoven fabric, wherein the absorption rate of water droplets dropped onto the film surface is within 60 seconds. The fibers of the nonwoven fabric can be general natural fibers such as cotton, hemp, or wool, but a key feature is the use of some water-absorbing fibers. Since this heat-insulating material is used for food, regenerated fibers such as rayon or acetate are preferred, while synthetic fibers such as polyethylene, polypropylene, or polyethylene terephthalate can be used for cost reasons.

[0009] The features of this invention are that the above-mentioned fibers contain, in the range of 1-10%, fibers made of hydrophilic sodium polyacrylate crosslinked material as water-absorbing fibers. Furthermore, the thickness of the nonwoven fabric is 0.3-3 mm (0.5-1.5 mm), and the basis weight of the nonwoven fabric is 20-250 g / m². 2 It is stated that this is the case, and more preferably 50-150 g / m² 2It is stated that this is the case.

[0010] Using a special water-absorbing resin improves the water retention capacity of the sheet, but this increases costs. Additionally, because the nonwoven fabric base is a resin film rather than a foam, there is a problem with insufficient heat insulation.

[0011] Patent Document 4 discloses a method for forming an embossed sheet by continuously engraving an embossed pattern onto a laminated sheet formed by bonding a resin foam sheet and a resin film. This invention discloses an embossing roll in which convex portions are formed on the bottom surface of the concave portions so as to form air reservoirs when the embossing roll is pressed against the sheet, and an embossing sheet manufactured therefrom is disclosed. Furthermore, a pipe cover is disclosed which is formed into a cylindrical shape so as to have an embossed pattern on its outer surface. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] Japanese Patent Publication No. 2020-197315 [Patent Document 2] Japanese Patent Publication No. 2014-065382 [Patent Document 3] Japanese Patent Application Publication No. 9-300511 [Patent Document 4] Japanese Patent Application Publication No. 9-314661 [Overview of the project] [Problems that the invention aims to solve]

[0013] It was previously known that condensation dripping could be prevented by attaching nonwoven fabric to the surface of the heat-insulating material. However, it was discovered that simply placing nonwoven fabric on the surface is insufficient to obtain a structure that prevents condensation dripping. Regardless of the material of the nonwoven fabric, it is necessary for the nonwoven fabric itself to have a specific structure. Therefore, the task was to specifically identify such a structure. [Means for solving the problem]

[0014] While the water absorption and condensation characteristics of nonwoven fabrics should differ depending on their material and structure, Patent Documents 1 and 2, which describe structures for preventing condensation dripping using nonwoven fabrics, do not include any description of the structure or water absorption of the nonwoven fabric. Patent Document 3 uses a special water-absorbing resin such as a crosslinked sodium polyacrylate, but the present invention provides a heat-insulating material for preventing condensation dripping that does not use such a resin, and can be used with either a general-purpose resin chemical fiber material that does not absorb water or a recycled fiber material that does absorb water, by fusing a nonwoven fabric having a predetermined structure to the surface of a polyethylene resin foam.

[0015] The present invention relates to a heat-insulating material for preventing condensation from dripping, which is formed by fusing or bonding a nonwoven fabric having a predetermined structure to at least one surface of a polyethylene resin foam. The present invention relates to a heat-insulating material for preventing condensation from dripping, a refrigerant piping and water supply / hot water supply piping structure and a building structure for preventing condensation from dripping using the same, a nonwoven fabric for preventing condensation from dripping, a method for forming a condensation from dripping structure for refrigerant piping using this heat-insulating material, and a method for forming a condensation from dripping structure for building components.

[0016] Here, in such a piping structure, in order to prevent the dripping of condensed water, by laminating a non-woven fabric on a foam which is a heat insulating material, it may be possible to prevent the dripping of condensed water by carrying the condensed water inside the non-woven fabric. However, simply laminating the non-woven fabric on the surface of the foam does not simply prevent the dripping of condensed water. It has been discovered that depending on the structure of the non-woven fabric, there are cases where condensation can be prevented and cases where it cannot be prevented. The three-dimensional structure of the fibers such as the porosity of the non-woven fabric, the degree of fiber bending, the structure of the fiber connection parts, and the entanglement of the fibers have an impact. However, the structure of the non-woven fabric is complex and cannot be directly defined. The present invention has been achieved by finding an alternative parameter that reflects the influence of the complex structure of the non-woven fabric on the dripping property of condensed water and defining this parameter.

[0017] In addition, in the present invention, as factors for defining the structure of the non-woven fabric used for the heat insulating material, the spatial structure of the fibers is defined based on the fiber diameter of the non-woven fabric to be used and the porosity of the fibers at a predetermined thickness. Furthermore, it has been found that the more the fiber bending parts are and the higher the crimpability, the better the property of preventing the dripping of condensed water. Also, as a parameter for evaluating the three-dimensional structure including the crimpability of the fibers, the structure of the fiber connection parts, and the degree of fiber entanglement, it has been found that there is a correlation between the tensile modulus value at a predetermined strain in a tensile test and the property of preventing the dripping of condensed water. The water retention property based on the above structure was evaluated by the amount of water retained per a predetermined non-woven fabric thickness, and it was confirmed that a non-woven fabric having a water retention amount of a predetermined amount or more has an excellent property of preventing the dripping of condensed water. Here, the tensile modulus refers to an effective tensile stress value obtained by dividing the apparent tensile stress in the same direction at a tensile elongation value of 5% in a tensile test by the filling rate. When the predetermined tensile modulus value or the effective tensile stress value satisfies a predetermined value, it means that the effective tensile stress, which is a value obtained by dividing the apparent tensile stress in the same direction at a tensile elongation value of 5% in a tensile test by the filling rate, satisfies 1 MPa or more and 25 MPa or less. That is, the tensile modulus and the effective tensile stress value are synonymous. Also, the apparent tensile stress refers to a value obtained by dividing the apparent tensile load by the cross-sectional area defined from the apparent thickness of the non-woven fabric measured based on JIS L1913 and the test piece width of the non-woven fabric.

[0018] Furthermore, after the non-woven fabric of the present invention is fused or adhered to the base polyethylene resin foam to be used as a heat insulating material, embossing of a predetermined shape is performed. Since the formability in this embossing is also considered to be affected by the three-dimensional structure of the non-woven fabric, particularly the filling rate and the tensile modulus value, the formability in embossing was confirmed.

[0019] In addition, even if the fibers used for the non-woven fabric are resins such as polyethylene resin, polypropylene resin, and PET that do not have water absorption, the water retention can be enhanced by the non-woven fabric satisfying predetermined structural conditions. Furthermore, the inventors have discovered that the non-woven fabric has excellent performance in preventing the dripping of condensed water, thus completing the present invention.

[0020] Of course, by the non-woven fabric satisfying predetermined structural conditions, it is also possible to use natural fibers such as cellulose and pulp having water absorption, regenerated fibers such as rayon and acetate, and semi-synthetic fibers within a predetermined quantitative range. In this case, the dripping prevention property of condensed water is further improved compared to the case of using resin fibers such as polyethylene resin, polyethylene resin, and polyester-based PET that do not have water absorption, but the strength of the non-woven fabric decreases. Therefore, the use of water-absorbent fibers needs to be limited to a predetermined quantitative range within the total fiber weight. In addition, particularly when natural fibers such as cellulose fibers and pulp are used for the non-woven fabric, it is difficult to produce long fibers due to the characteristics of natural fibers, and the fiber length is unstable. Therefore, it is desirable to use short fibers.

[0021] In addition, since the present invention is ensured by the non-woven fabric used for the heat insulating material, in the present invention, in addition to the heat insulating material for preventing the dripping of condensed water, the piping structure for preventing the dripping of condensed water using this, and the building structure for preventing the dripping of condensed water, the invention of the non-woven fabric for preventing the dripping of condensed water used for this is also added. In addition, the invention of the method for forming the dripping prevention structure of condensed water in the refrigerant piping structure and the building members using this heat insulating material is also added.

[0022] This is a heat-insulating material for preventing condensation from dripping, comprising a polyethylene resin foam with a nonwoven fabric placed on its surface, wherein the base material is a sheet-like polyethylene resin foam having closed cells, and the nonwoven fabric is fused or bonded to one surface of the base material, the average fiber diameter of the fibers constituting the nonwoven fabric is in the range of 10 to 30 μm, the porosity of the fibers is 85 to 98%, and furthermore, the nonwoven fabric satisfies an effective tensile stress of 25 MPa or less and 1 MPa or more, which is the value obtained by dividing the tensile elongation in the MD direction in a tensile test by the packing density in the same direction at 5%. In other words, it is sufficient that the effective tensile stress in the MD direction is 25 MPa or less and 1 MPa or more, and the effective tensile stress in the TD direction does not necessarily have to satisfy the range of 25 MPa or less and 1 MPa or more. Here, the thickness of the polyethylene resin foam is at least 10 mm or more to ensure heat insulation, so usually 10 mm is sufficient to obtain the desired heat insulation performance. Conversely, if the foam is made too thick, the product dimensions, such as the thickness and diameter of the product after coating with insulation material, will increase, so 10mm is preferable.

[0023] In this case, the average fiber diameter of the fibers is set to a range of 10 to 30 μm because if the fiber diameter is 10 μm or less, the strength of the nonwoven fabric is insufficient, reducing the durability of the protective member surface during use. When the insulating material is heat-fused between the nonwoven fabric and the foam, the nonwoven fabric itself deforms, resulting in insufficient elastic recovery after fusion, and problems such as the fibers collapsing and fusing in a planar manner. Conversely, if the fiber diameter exceeds 30 μm, the increase in fiber diameter increases the spatial occupancy rate of the fibers themselves, making it difficult to form a three-dimensionally stable space with a high porosity, thus making it difficult to maintain a porosity in the range of 85 to 98%. Here, when the nonwoven fabric is composed of multiple fibers, the average fiber diameter referred to in this invention preferably satisfies the above range for the average fiber diameter of each constituent fiber, but it is the average fiber diameter (number average) of those fibers that satisfies the above range.

[0024] Looking at the porosity, if the porosity falls below 85%, the proportion of fibers per unit volume increases, making it impossible to retain sufficient water. Furthermore, if the porosity exceeds 98%, although the space for forming a water film increases, the water film cannot be maintained, resulting in decreased water retention, as well as a decrease in the shape stability of the nonwoven fabric itself and the elastic recovery of the nonwoven fabric after molding.

[0025] Furthermore, the tensile modulus (effective tensile stress) is calculated by dividing the normal tensile stress value by the packing density, thus eliminating the influence of fiber packing density (porosity). Therefore, it is considered a value that comprehensively includes information about the degree of crimping of the fibers themselves and the degree of fiber orientation within the nonwoven fabric. This is an important parameter because, assuming the same porosity, the more crimped the fibers are and the less orientation they have, the smaller the distance between adjacent fibers in three dimensions, allowing the nonwoven fabric to retain more water. In fact, when the effective tensile stress exceeds 25 MPa, the rigidity of the nonwoven fabric increases, while water retention decreases, resulting in insufficient water retention and reduced embossing properties, which is undesirable. Also, when the effective tensile stress in both the MD and TD directions falls below 1 MPa, there is sufficient space to retain condensation water, but the bonding and entanglement of the fibers within the nonwoven fabric becomes insufficient, making it difficult to maintain the shape of the nonwoven fabric and thus difficult to handle in the manufacturing process of this invention. Therefore, it is considered necessary that the effective tensile stress in at least one direction exceeds 1 MPa in both directions.

[0026] The nonwoven fabric of the aforementioned heat-insulating material has a thickness of 1.0 mm or less, as measured according to JIS L1913, and the water retention capacity per 1 mm of apparent thickness of the nonwoven fabric is 500 g / m². 2 That's fine too.

[0027] The fibers constituting the nonwoven fabric of the heat-insulating material may be composed of fibers containing at least one of the following: PET resin, polyethylene resin, polypropylene resin, or acrylic resin. Furthermore, the fibers constituting the nonwoven fabric of the heat-insulating material may also contain cellulose, pulp, or rayon fibers in an amount of 30% or less of the total fiber weight. In terms of nonwoven fabric strength, it is more preferable that the total fiber weight be 15% or less. When using natural fibers, it is preferable to use short fibers because it is difficult to obtain long fibers.

[0028] At least a portion of the fibers constituting the nonwoven fabric of the heat-insulating material include fibers having a core-sheath structure, wherein the sheath portion of the fiber having a core-sheath structure is formed of a resin with a lower melting point than the core portion, or the core fiber of the core-sheath structure is a hollow fiber, and a sheath portion is formed around the hollow fiber, forming a hollow multilayer structure fiber, wherein the core portion or the sheath portion of the fiber forming the hollow core portion is formed of a resin with a lower melting point than the core portion. By making the core portion a hollow structure, the flexibility of the nonwoven fabric can be improved. At least a portion of the fibers constituting the nonwoven fabric may be formed of short fibers, or of either warp-and-weft or warp-and-weft or warp-and-weft or warp-and-beam or warp-and-beam or warp-and-beam or warp-and-beam or diagonal orbicular

[0029] Furthermore, the nonwoven fabric formed on the surface of the resin foam may be embossed to prevent condensation from dripping. By embossing in this way, the shape of the outer surface of the nonwoven fabric can be stabilized, and the shape stability when the nonwoven fabric is wrapped around pipes, ducts, etc., can be increased.

[0030] The aforementioned heat-insulating material for preventing condensation from dripping is a heat-insulating material for preventing condensation from dripping made of polyethylene resin foam and nonwoven fabric, wherein the base material is a polyethylene resin foam having closed cells in a sheet shape, with a nonwoven fabric fused to one surface, the average fiber diameter of the fibers is in the range of 10 to 30 μm, the porosity of the fibers is 85 to 98%, and furthermore, the tensile elongation in the MD direction in a tensile test satisfies the effective tensile stress, which is the value obtained by dividing the apparent stress in the same direction at 5% by the packing ratio, between 25 MPa and 1 MPa, and furthermore, the tensile elongation in the TD direction in a tensile test satisfies the effective tensile stress, which is the value obtained by dividing the apparent stress in the same direction at 5% by the packing ratio, between 25 MPa and 1 MPa.

[0031] In other words, it is even more desirable that the effective tensile stress value obtained by dividing the apparent stress at 5% by the packing density, calculated by the tensile elongation in the MD and TD directions in the tensile test, is 20 MPa or less and 1 MPa or more. More preferably, it is preferable that the effective tensile stress value obtained by dividing the apparent stress at 5% by the packing density, calculated by the tensile elongation in the tensile test in either the MD or TD direction, is 20 MPa or less and 2 MPa or more. By satisfying these characteristics, it is possible to obtain a thermal insulation material in which the effective tensile stress in both the MD and TD directions satisfies the predetermined value, and thus a thermal insulation material with excellent condensation drip prevention performance that has little influence on the direction when the thermal insulation material is used can be obtained, and thus condensation dripping can be prevented even when the thermal insulation material is used in a vertical direction.

[0032] The aforementioned condensation-preventing insulation material may be a piping system characterized by having a nonwoven fabric covering the outer circumference of the refrigerant piping or hot water piping with the outer surface facing outwards. This improves the insulation performance of the piping and prevents condensation.

[0033] This spectacle-shaped piping structure integrates two pipes by heat-sealing or heat-bonding the condensation-preventing insulation material covering the outer circumference of the refrigerant pipes to each other.

[0034] A cylindrical refrigerant piping structure may also exist, characterized in that components are provided to be housed inside multiple refrigerant pipes, drain pipes, and wiring pipes, and the condensation drip-preventing insulation material surrounds the multiple refrigerant pipes, drain pipes, and wiring pipes such that the nonwoven fabric-formed surface of the condensation drip-preventing insulation material has a substantially cylindrical cross-sectional shape, thereby housing the components housed inside the condensation drip-preventing insulation material. Such a piping structure may also exist, which can prevent condensation by collectively insulating multiple pipes.

[0035] A cylindrical piping structure for water supply and hot water supply may be provided, in which a cross-linked polyethylene pipe and a resin sheath pipe covering the outer circumference of the cross-linked polyethylene pipe are prepared, and the condensation drip-preventing insulation material surrounds the cross-linked polyethylene pipe and the resin sheath pipe covering the outer circumference of the cross-linked polyethylene pipe, with the non-woven fabric surface forming the outer surface and the shape of the outer surface of the condensation drip-preventing insulation material having a substantially cylindrical cross-section, and the cross-linked polyethylene pipe and the sheath pipe are housed inside the condensation drip-preventing insulation material.

[0036] The resin sheath pipe may be a cylindrical piping structure for water supply and hot water supply piping, in which the outer circumference of the sheath pipe is covered with a resin foam.

[0037] The piping structure is such that the condensation drip-preventing insulation material covers the outer circumference of the refrigerant piping, and at least a portion of the piping includes vertical piping, and the vertical piping structure is such that the nonwoven fabric surface of the condensation drip-preventing insulation material covers the vertical piping so that the nonwoven fabric surface of the condensation drip-preventing insulation material becomes the outer surface of the vertical piping. Here, it is desirable that the condensation drip-preventing protective member wrapped around the vertical piping is a nonwoven fabric with an average fiber diameter in the range of 10 to 30 μm, a porosity of 85 to 98% of the fibers, and a tensile elongation in the MD and TD directions such that the apparent stress in those directions at 5% divided by the packing density is 20 MPa or less and satisfies 1 MPa or more.

[0038] The structure of the air conditioning duct may be such that the aforementioned condensation drip-preventing insulation material is bonded to the outer surface of the air conditioning duct with the nonwoven fabric forming surface facing the outer surface. By covering the outer periphery of the air conditioning duct with the condensation drip-preventing insulation material of the present invention in this way, the thermal insulation performance of the air conditioning duct can be improved, and condensation on the outer periphery of the duct can be prevented. In this case, it is desirable that the nonwoven fabric bonded to the outer surface of the air conditioning duct is a nonwoven fabric that satisfies the effective tensile stress, which is the value obtained by dividing the tensile elongation in the MD and TD directions in a tensile test by the packing density, between 25 MPa and 1 MPa.

[0039] The condensation drip prevention structure for inorganic building boards may be such that the aforementioned condensation drip prevention insulation material is placed on the surface of an inorganic building board with its nonwoven fabric-forming surface as the outer surface, or that the resin foam surface of the condensation drip prevention insulation material placed on the surface of the inorganic building board with its nonwoven fabric-forming surface as the outer surface and the opposing surfaces of the inorganic building board are bonded to each other and arranged in the horizontal plane, and the inorganic building board is at least one of gypsum board or calcium silicate board.

[0040] The condensation drip prevention insulation material is placed on the surface of an inorganic building board with its nonwoven fabric-forming surface facing outward, and the opposing surfaces of the resin foam surface of the condensation drip prevention insulation material and the surface of the inorganic building board are bonded to each other. The inorganic building board is arranged in a vertical plane direction, and the inorganic building board is at least one of gypsum board or calcium silicate board.

[0041] In this case, the inorganic building board material is arranged in the vertical plane direction, and the nonwoven fabric bonded to the outer surface of the inorganic building board material is preferably a nonwoven fabric that satisfies the requirement that the effective tensile stress, which is the value obtained by dividing the apparent stress in the MD and TD directions at 5% by the packing density, is 25 MPa or less and 1 MPa or more.

[0042] The aforementioned condensation drip prevention insulation material may be bonded to the inner surface of the corrugated metal roof to prevent condensation from dripping. By bonding the condensation drip prevention insulation material to the inner surface of the corrugated metal roof in this way, it is possible to improve the thermal insulation of the inner surface of the roof and prevent condensation on the inner surface of the roof. In this case, it is desirable that the nonwoven fabric used in the condensation drip prevention structure for the corrugated metal roof be a nonwoven fabric whose tensile modulus in both the MD direction and the TD direction satisfies predetermined values, similar to that of air conditioning ducts.

[0043] The nonwoven fabric may be one in which the average fiber diameter of the fibers constituting the nonwoven fabric is in the range of 10 to 30 μm, the porosity of the fibers is 85 to 98%, the thickness of the nonwoven fabric measured according to JIS L1913 is 1.0 mm or less, and the tensile elongation in the MD direction in a tensile test satisfies a value of 25 MPa or less and 1 MPa or more obtained by dividing the apparent stress in the same direction at 5% by the packing density.

[0044] The water retention capacity of the aforementioned nonwoven fabric, calculated per 1 mm of apparent thickness, is 500 g / m². 2 The nonwoven fabric characterized above may be used as a nonwoven fabric for preventing condensation from dripping by fusing it to the surface of a polyethylene resin foam.

[0045] The fibers constituting the nonwoven fabric are composed of fibers containing at least one of the following: PET resin, polyethylene resin, polypropylene resin, or acrylic resin, and the fibers may also not have a core-sheath structure. Furthermore, the fibers constituting the nonwoven fabric may also contain 30% or less of absorbent fibers, such as cellulose fibers, pulp, or rayon fibers, by total weight. The reason for limiting the absorbent fiber content to a predetermined value is to prevent a decrease in strength due to an increase in water absorption. When using natural fibers such as cellulose fibers or pulp, it is difficult to use long fibers of a predetermined length, so it is preferable to use short fibers.

[0046] Furthermore, the nonwoven fabric for preventing condensation from dripping may be composed of fibers having a core-sheath structure, and if it has a core-sheath structure, the sheath portion may be made of a resin with a lower melting point than the core portion. Moreover, the core fiber of the core-sheath structure may be a hollow fiber, and the sheath portion may be formed around the hollow fiber to create a hollow multilayer structure. By making the core a hollow structure, it becomes possible to ensure the flexibility of the nonwoven fabric.

[0047] The aforementioned nonwoven fabric can also be a nonwoven fabric for preventing condensation dripping, characterized in that the tensile elongation values ​​in the MD direction and TD direction in a tensile test satisfy both conditions: the effective tensile stress, which is the value obtained by dividing the apparent stress in each direction at 5% by the packing density, is 25 MPa or less and 1 MPa or more. By satisfying these characteristics, it is possible to obtain a nonwoven fabric for preventing condensation dripping that has excellent condensation dripping prevention performance in both directions or that has condensation dripping prevention performance regardless of the installation direction.

[0048] The fibers constituting the nonwoven fabric may consist of short fibers comprising at least one of PET resin, polyethylene resin, polypropylene resin, or acrylic resin, and further comprising fibers that do not have a normal core-sheath structure or fibers that have at least a part of a core-sheath structure, and in the case of having a core-sheath structure, the sheath portion may be made of a resin with a lower melting point than the core portion, thus forming a nonwoven fabric for preventing condensation from dripping. In addition, the fibers constituting the nonwoven fabric may further contain cellulose fibers, pulp, or rayon fibers in an amount of 30% or less of the total fiber weight. The reason for keeping the water-absorbing fiber content below a predetermined value is to prevent a decrease in strength due to an increase in water absorption.

[0049] In this way, by using a non-melting type fiber in which the sheath portion is formed of a resin with a lower melting point than the core portion, heat fusion can be performed at a lower temperature range than the core portion, which has a higher melting point. This allows the physical and mechanical properties of the core fiber to be maintained even after fusion. Furthermore, by making the core portion a hollow structure, the flexibility of the nonwoven fabric can be improved.

[0050] The aforementioned nonwoven fabric of short fibers can be a nonwoven fabric manufactured by chemical bonding, thermal bonding, spunlace, air-laid, needle punching, or the like. By using at least a portion of the short fibers manufactured by such methods in the nonwoven fabric, condensation can be prevented even when the nonwoven fabric is used vertically rather than horizontally. Furthermore, even without using short fibers, nonwoven fabrics with orthogonal warp and weft orientation or diagonal warp and weft orientation can be used as nonwoven fabrics that can reduce the influence of fiber orientation.

[0051] The method for constructing a piping structure in which the aforementioned condensation drip-preventing insulation material is wrapped around the outer circumference of a refrigerant pipe, and in the case where the pipe is a vertical pipe or an inclined pipe, the method for forming the piping structure may be such that the direction in which the condensation drip-preventing insulation material satisfies an effective tensile stress of 25 MPa or less and 1 MPa or more is oriented in a horizontal direction perpendicular to the direction of the vertical pipe.

[0052] In this case, if the piping used to prevent condensation from dripping is vertical or inclined, a longer vertical length of piping will result in a competition between evaporation from the nonwoven fabric surface and the increase in moisture accumulated within the nonwoven fabric due to the influence of gravity. However, since there is a possibility of condensation dripping from the bottom of the piping, it is conceivable to improve the effective tensile stress in the TD direction to accelerate evaporation from the nonwoven fabric surface by promoting movement of the nonwoven fabric to the sides, thereby promoting evaporation from the nonwoven fabric surface and preventing condensation from dripping.

[0053] In a method for forming a structure to prevent condensation from dripping in an air conditioning duct, the side surfaces of the air conditioning duct are provided opposite each other so as to sandwich the upper and lower surfaces of the duct in at least a vertical direction, and the nonwoven fabric surface of the nonwoven fabric insulation material for preventing condensation from dripping is arranged on the side surface with the direction in which the effective tensile stress of the nonwoven fabric satisfies 25 MPa or less and 1 MPa or more, in a horizontal direction perpendicular to the vertical side surface of the duct.

[0054] In a method for forming a structure to prevent condensation from dripping on inorganic building materials, if the condensation structure of the inorganic building materials is a vertical wall structure, it is desirable to form a structure to prevent condensation from dripping on inorganic building materials by arranging the nonwoven fabric of the insulating material as the outer surface on the surface of the vertical wall of the inorganic building materials, with the direction in which the effective tensile stress of the nonwoven fabric of the insulating material to prevent condensation from dripping is satisfied as 25 MPa or less and 1 MPa or more, in a horizontal direction perpendicular to the direction of the vertical wall structure. Furthermore, in a method for forming a structure to prevent condensation from dripping on a corrugated metal roof, it is desirable to form a structure to prevent condensation from dripping on a corrugated metal roof by arranging the nonwoven fabric of the insulating material as the outer surface on the back surface of the corrugated metal roof, with the direction in which the effective tensile stress of the nonwoven fabric of the insulating material to prevent condensation from dripping is satisfied as 25 MPa or less and 1 MPa or more, in a direction perpendicular to the bending direction of the corrugated metal of the corrugated metal roof. In this case, since the drainage slope when laying a standard corrugated metal roof is usually around 3 / 100, this has almost no effect on the dripping of condensation water.

[0055] The present invention provides a heat-insulating material for preventing condensation from dripping, characterized in that a nonwoven fabric is fused to at least one surface of a polyethylene resin foam, the average fiber diameter of the fibers constituting the nonwoven fabric is in the range of 10 to 30 μm, the porosity of the fibers is 85 to 98%, and furthermore, the tensile elongation in the MD direction in a tensile test satisfies a value of 25 MPa or less and 1 MPa or more when the apparent stress in the same direction at 5% is divided by the packing density.

[0056] Here, using the above-mentioned heat-retaining material, the thickness of the nonwoven fabric measured according to JIS L1913 is 1.0 mm or less, and the water retention capacity converted to 500 g / m² per 1 mm of apparent thickness of the nonwoven fabric is 500 g / m². 2The above requirements can be satisfied. The condensation drip prevention performance in this invention can be obtained regardless of the water absorption capacity of the fibers themselves, so both chemical and natural fiber materials can be used as the fibers constituting the nonwoven fabric. Furthermore, the nonwoven fabric of this invention has the characteristic of being excellent not only in condensation drip prevention but also in embossability, as the fiber diameter is within a predetermined range, in addition to the porosity and tensile modulus, which are parameters that indirectly reflect the three-dimensional structure of the fibers. In the heat-insulating material of this invention, fusion bonding is preferable for joining the nonwoven fabric to the foam, but it may also be arranged by bonding with adhesive.

[0057] The mechanism for preventing condensation droplets in the heat-insulating material of the present invention is thought to be as follows. First, when minute condensation occurs at the interface between the foam and the nonwoven fabric, the minute condensation water diffuses in the thickness direction due to the capillary action of the nonwoven fabric. As the water diffused in the thickness direction has a larger contact area with the outside air, it becomes more easily heated by the outside air, thereby suppressing the continuation of the condensation phenomenon and preventing the water droplets from growing larger.

[0058] Furthermore, it is believed that condensation is suppressed as the condensed water diffuses and evaporates from the surface of the nonwoven fabric. In this case, by setting a predetermined fiber diameter and porosity, the value obtained by dividing the stress at the 5% tensile elongation by the filling density is set to a predetermined range, thereby preventing the dripping of condensed water and creating a nonwoven fabric that retains a predetermined amount of moisture. However, even if the fiber diameter and porosity satisfy the predetermined values, if the value obtained by dividing the stress at the 5% tensile elongation by the filling density does not satisfy the predetermined range, condensation cannot be prevented.

[0059] In addition to the above, when nonwoven fabric is wrapped around a pipe, the nonwoven fabric wrapped around the outer circumference of the insulation material in a roughly cylindrical cross-section has a height difference in the vertical direction compared to when the nonwoven fabric of the insulation material is used in a flat manner. Due to the suction effect of capillary action and the downward movement of moisture due to gravity, a gradient in the amount of water contained in the nonwoven fabric occurs at the top and bottom of the pipe structure covered with insulation material, resulting in a higher water content at the bottom of the pipe compared to the top.

[0060] For example, in the case of horizontal piping, the amount of water on the top surface of the pipe is small, resulting in a large contact area with the atmosphere. Water evaporates from the top surface of the pipe, and water is absorbed from the bottom to the top surface by capillary action. By maintaining a predetermined relationship between evaporation and absorption, condensation from the pipe can be prevented. Furthermore, in the case of vertical piping or vertical walls where there is a difference in the coverage of the insulation material from top to bottom, the effect of gravity is greater than in the case of horizontal piping, so it is necessary to consider the effect of gravity on condensation. However, if the moisture retained by the nonwoven fabric can be released horizontally by capillary action, thereby increasing the contact area with the air and accelerating the evaporation of condensed water, this problem can be solved.

[0061] In other words, if the nonwoven fabric of the present invention is constructed such that the direction in which the tensile elongation value in a tensile test is satisfied by dividing the apparent stress in the same direction at 5% by the packing density is 25 MPa or less and 1 MPa or more coincides with the horizontal direction when the nonwoven fabric is installed, or if a nonwoven fabric with improved anisotropy that satisfies the predetermined value regardless of whether the MD direction or TD direction of the nonwoven fabric is installed to coincide with the horizontal direction, then it becomes possible to solve the problem of condensation in thermal insulation materials and provide a nonwoven fabric that can prevent condensation. Of course, in this case as well, it goes without saying that the fiber diameter and porosity of the nonwoven fabric used must satisfy the range of the present invention, which is an average fiber diameter of 10 μm to 30 μm and a porosity of 85 to 95%.

[0062] A condensation-preventing piping structure can be obtained by covering the outer circumference of refrigerant piping with the aforementioned condensation-preventing insulation material, and a condensation-preventing air conditioning duct can be obtained by adhering or covering the outer surface of an air conditioning duct with the condensation-preventing insulation material. Furthermore, a condensation-preventing structure for inorganic building panels can be obtained by placing the condensation-preventing insulation material on the surface of the inorganic building panel, and a condensation-preventing structure for inorganic building panels arranged as vertical walls can be obtained by adhering the condensation-preventing insulation material on the surface of the inorganic building panel. A condensation-preventing corrugated sheet roof structure can be obtained by adhering it to the inner surface of a corrugated sheet roof. Naturally, a nonwoven fabric with excellent water retention and condensation-preventing performance can be obtained. [Effects of the Invention]

[0063] According to the present invention, in a heat-insulating material having a nonwoven fabric arranged on the surface of a polyethylene resin foam, the ability to prevent condensation from dripping can be improved regardless of the material of the nonwoven fabric. [Brief explanation of the drawing]

[0064] [Figure 1] (a) is a diagram showing the test conditions of a condensation test material using a constant temperature and humidity chamber, and (b) is a diagram showing the condition of the condensation drip prevention insulation material wrapped around the refrigerant pipe. [Figure 2] Figure 2(a) shows a perspective view of a refrigerant pipe covered with insulating material 3 to prevent condensation dripping around its outer circumference, and Figure 2(b) shows a cross-sectional view obtained by cutting Figure 2(a) at a predetermined position including the straight line XX. [Figure 3] Figure 3(a) shows a piping structure in which pipes covered with the condensation drip-preventing insulation material of the present invention are arranged opposite each other and integrated, and Figure 3(b) shows a cross-sectional view obtained by cutting Figure 3(a) at a predetermined position including the straight line AA. [Figure 4] Figure 4 shows a cylindrical refrigerant piping structure in which existing refrigerant piping is surrounded by the heat-insulating material of the present invention. [Figure 5(a)]Figure 5(a) shows a cylindrical piping structure for water supply and hot water supply, in which a protective resin casing is placed over the outer circumference of the water supply and hot water supply piping, and the protective member of the present invention is placed on the outer circumference of the piping. [Figure 5(b)] Figure 5(b)(c) shows a cylindrical piping structure for water supply and hot water supply in which the outer circumference of a resin sheath is covered with resin foam, and the outer circumference of the resin foam is further covered with the protective member of the present invention. Figure 5(d) is a cross-sectional view taken at a predetermined position including the straight line BB in the perspective view (c). [Figure 6] Figure 6 shows a piping structure in which the protective member of the present invention is applied to vertical piping. [Figure 7] Figure 7 shows a structure for preventing condensation from dripping in a duct using the heat-insulating material of the present invention. [Figure 8] Figure 8(a) shows a condensation drip prevention structure for inorganic building panels in which a heat-insulating material for preventing condensation dripping is placed on the surface of the inorganic building panels, and Figure 8(b) shows a condensation drip prevention structure for inorganic building panels in which the inorganic building panels, in which a heat-insulating material for preventing condensation dripping is placed on the surface of the inorganic building panels, are arranged as vertical walls. [Figure 9] Figure 9 shows a corrugated metal roof structure in which steel plates are folded and laminated with the nonwoven fabric of the present invention as the heat-insulating material on the underside of the steel plates of the corrugated metal roof. [Figure 10(a)] Figure 10(a) is a 100x magnification SEM image of nonwoven fabric 4, which has excellent resistance to condensation dripping. [Figure 10(b)] Figure 10(b) is an optical microscope image at 100x magnification of nonwoven fabric 4, which has excellent resistance to condensation dripping, after water absorption. [Figure 10(c)] SEM image at 100x magnification of test material 19, a nonwoven fabric made of diagonally interwoven fibers. [Figure 10(d)] SEM image of a nonwoven fabric using short fibers corresponding to test material 18. [Modes for carrying out the invention]

[0065] The embodiments for carrying out the present invention will be described in detail below.

[0066] The present invention provides a heat-insulating material for preventing condensation from dripping, wherein the base material is a polyethylene-based resin foam having closed cells, and a nonwoven fabric is disposed on at least one surface of the polyethylene-based resin foam, and the nonwoven fabric satisfies a predetermined configuration, thereby providing a heat-insulating material that prevents condensation from dripping.

[0067] A crosslinking foaming method is used as a method for producing the polyethylene foam that constitutes the base material of the heat-insulating material for preventing condensation dripping of the present invention. An extrusion crosslinking foaming method can be used, in which crosslinking is performed by extrusion and then foaming is performed after crosslinking.

[0068] (Polyethylene-based resin foam) For polyethylene foams, polyethylene resins such as LDPE and HDPE can be used individually or as a mixture of LDPE and HDPE.

[0069] Furthermore, these polyethylene foams can be given heat resistance and flame retardancy as needed. When using a mixed resin of LDPE and HDPE, the LDPE and HDPE can be mixed in a predetermined ratio, for example, 40 parts by mass of LDPE to 60 parts by mass of HDPE. In addition, as will be described later, in this invention, it is possible to make the polyethylene resin foam heat-resistant or flame-retardant by adding heat-resistant or flame-retardant agents. Beyond the above, polyethylene resin foams with various additives can be used as long as they do not inhibit foaming or cause resin degradation.

[0070] Polyethylene-based resins can include LDPE and HDPE, as well as polyethylene-modified resins such as EVA (polyethylene copolymerized with vinyl acetate). The reason for using EVA instead of polyethylene is that its high flexibility and elasticity allow it to be used in a wide variety of product applications. For example, LDPE can be F120N manufactured by Ube Maruzen Polyethylene Co., Ltd., HDPE can be HD1300 manufactured by Nippon Polyethylene Co., Ltd., and EVA can be DQDJ-1868 manufactured by ENEOS NUC Corporation.

[0071] (Crosslinking agents, foaming agents, etc.) Here, the content of the crosslinking agent and blowing agent used in polyethylene foam may vary. For example, in the case of a foaming ratio of 20 to 40 times, the crosslinking agent may be included in a range of 0.6 to 1.5 parts by weight and the blowing agent in a range of 10 to 30 parts by weight per 100 parts by weight of polyethylene resin. While the above ranges are desirable for the crosslinking agent and blowing agent, they can be changed as needed.

[0072] For example, dicumyl peroxide can be used as a crosslinking agent. For example, as a dicumyl peroxide used as a crosslinking agent, Nippon Oil & Fats Co., Ltd.'s product name Permil D can be used. As for the blowing agent, inorganic blowing agents may be used, but organic decomposition type blowing agents such as azodicarbonamide (ADCA), for example, Eiwa Chemical Co., Ltd.'s product name Vinihole AC#LQ, can be preferably used.

[0073] As blowing agents, in addition to azodicarbonamide (ADCA), oxybisbenzenesulfonyl hydrazide (OBSH), N,N'-dinitrosopentamethylenetetramine (DPT), p-toluenesulfonyl hydrazide, benzenesulfonyl hydrazide, diazoaminobenzene, N,N'-dimethyl-N,N'-dinitroterephthalamide, and azobisisobutyronitrile can be used, and these can be used individually or in combination of two or more. Any of these blowing agents may be used. Typically, azodicarbonamide (ADCA) is the most commonly used blowing agent.

[0074] In addition to the above, crosslinking agents and foaming agents may be added as needed. For example, TMPT (trimethylolpropane trimethacrylate), trade name: Ogmont, may be added as a crosslinking agent, while zinc oxide can be used as a foaming agent.

[0075] (Heat resistance improver, flame retardant) To impart heat resistance, at least 2.0 parts by mass or less of either carbon or titanium oxide (rutile type), or both, of a heat-resistant pigment can be added per 100 parts by mass of resin. Carbon has high conductivity and therefore has a heat dissipation effect, titanium oxide has excellent heat reflectivity, and both carbon and titanium oxide have high heat resistance, thus improving the heat resistance of the resin foam.

[0076] Furthermore, to improve the flame retardancy of the foam, a flame retardant is added. The flame retardant can be added in a total of 100 parts by mass per 100 parts by mass of resin, including antimony trioxide, magnesium hydroxide, aluminum hydroxide, other antimony-based flame retardants, hydroxide-based flame retardants, and bromine-based flame retardants. In addition to the above-mentioned antimony-based, bromine-based, and hydroxide-based flame retardants, inorganic fillers may also be added.

[0077] For example, if the flame retardant content exceeds 100 parts by mass, the effect saturates and foaming is inhibited; therefore, the total amount of flame retardant added should be 100 parts by mass or less. If the flame retardant content exceeds 100 parts by mass, foaming is inhibited by the flame retardant; therefore, the upper limit must be 100 parts by mass or less. Here, the preferred content of antimony-based flame retardants and bromine-based flame retardants is 20 parts by mass or less each, and the preferred content of hydroxide-based flame retardants is 80 parts by mass or less. Note that since the specific gravity of all flame retardants is higher than that of the resin components, when converted to a volume ratio for mixing, the mixing ratio to the resin components becomes significantly smaller than the mass ratio; therefore, there are no particular problems within the above ranges.

[0078] (Inorganic fillers) Inorganic fillers may be included to the extent that they do not impair foaming, impact resistance, or fire resistance (uniformity of the carbonized layer thickness). Examples of inorganic fillers include calcium silicate, zeolite, talc, mica, silica, alumina, diatomaceous earth, calcium oxide, magnesium oxide, iron oxide, tin oxide, barium carbonate, magnesium carbonate, and montmorillonite. Since a high content of inorganic fillers inhibits foaming, it is preferable that at least one of the inorganic fillers be included in a quantity of 2 parts by mass or less. Furthermore, it is desirable that the content of these inorganic fillers be 1 part by mass or less.

[0079] (Antioxidant, stabilizer) Since antioxidants can inhibit the foaming of resin foams, it is desirable to use them in small amounts. In addition to antioxidants, light stabilizers, weather-resistant agents, etc. may be included depending on the circumstances. By incorporating antioxidants, oxidative degradation of the base resin constituting the foam can be prevented.

[0080] Antioxidants include phenolic antioxidants, phosphite antioxidants, and blends of phenolic and phosphite antioxidants. Antioxidants that satisfy the above requirements include, for example, hindered phenolic antioxidants and hindered amine compounds. These antioxidants have effects not only as antioxidants but also as stabilizers or weather-resistant agents. For example, in this invention, specifically, tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane is used, and Irganox 1010 manufactured by BASF is used.

[0081] The antioxidant content is preferably 0.05 to 1.0 part by mass per 100 parts by mass of polyethylene resin. If the antioxidant content is too high, crosslinking of the base resin is inhibited, the viscosity decreases, the bubble diameter increases, and gas escape occurs, reducing the foaming ratio and potentially inhibiting foaming. Therefore, it is desirable not to add more than 1.0 part by mass of antioxidant.

[0082] (Other additives) The resin foam in the present invention may further contain other additives, such as lubricants, pigments including carbon and titanium dioxide, dyes, plasticizers, fillers, and antistatic agents, depending on the purpose, to the extent that they do not inhibit foaming. For example, these other additives can be added in amounts of 2 parts by mass or less. For example, by adding a predetermined amount of inorganic pigment, aesthetic appeal and design can be imparted. Known commercially available additives can be used for these additives.

[0083] (Method for manufacturing polyethylene resin foam) Here, a method for producing polyethylene resin foam will be explained using low-density polyethylene as the base resin. First, an organic decomposition type foaming agent and a crosslinking agent are mixed with low-density polyethylene as the base resin, kneaded in a pressurized kneader, and pelletized to obtain pellets of a foamable resin composition. These pellets are then fed into the hopper of a short-shaft extruder and extruded through a die of a predetermined width to obtain a foaming base material sheet of a predetermined thickness.

[0084] The resin foam is extruded from a foaming base sheet at 120-150°C, then continuously foamed to a predetermined ratio in a heating furnace at 200-230°C, and then passed through rolls to adjust the dimensions and surface properties of the foam before being cut to a predetermined width corresponding to the diameter of the pipe to be wrapped around it.

[0085] The foaming ratio needs to be controlled considering thermal insulation, embossability, and cushioning properties. If the foaming ratio is too high, it becomes difficult to perform stable and uniform embossing after lamination with nonwoven fabric. If the foaming ratio is too low, the rigidity of the resin becomes too high, making it difficult to obtain the desired emboss height and reducing thermal insulation. Therefore, a foaming ratio of 20 to 40 times is desirable for the resin foam, and there are no particular problems within this range. Cushioning is not a particular problem if the foaming ratio is in the range of 20 to 40 times. In this embodiment, the foam was foamed to 30 times. When foaming to 30 times, 16 parts by mass of an organic decomposition type foaming agent and 0.8 parts by mass of a crosslinking agent can be added to 100 parts by mass of polyethylene resin. In other words, the content of the foaming agent and crosslinking agent can be appropriately adjusted according to the foaming ratio.

[0086] In this case, a mixed resin of LDPE and HDPE in a mass ratio of 4:6 may be used as the polyethylene resin. For LDPE, F120N manufactured by Ube Maruzen Polyethylene Co., Ltd. was used, and for HDPE, HD1300 manufactured by Nippon Polyethylene Co., Ltd. was used. For the foaming agent, product name Vinihole AC#LQ manufactured by Eiwa Kasei Co., Ltd. was used, and for the crosslinking agent, product name Parkmill D manufactured by Nippon Oil & Fats Co., Ltd. was added in the above proportions.

[0087] In this invention, a heat-insulating material for preventing condensation from dripping can be obtained by bonding a nonwoven fabric to at least one surface of a polyethylene-based resin foam by fusion. Next, the nonwoven fabric to be placed on the polyethylene-based foam will be described. Here, the bonding of the nonwoven fabric to the resin foam may be done by adhesive rather than fusion.

[0088] (Non-woven fabric) First, to clarify the definition of nonwoven fabric, JIS defines it as "a material made by laminating fibers without weaving them together and spreading it out into a sheet, such as a fiber sheet, web, or pad, in which the fibers are oriented in one direction or randomly, and the fibers are bonded together by entanglement and / or fusion and / or adhesion. However, paper, woven fabrics, tufts, and crinkled felt are excluded."

[0089] (Fibers used in nonwoven fabrics) The nonwoven fabric of the present invention does not exclude the use of natural material fibers or natural material resins such as rayon resins and acetate resins, but primarily prevents condensation by controlling the three-dimensional structure of the nonwoven fabric by setting the fiber diameter and porosity of the fibers constituting the nonwoven fabric within a predetermined range and by setting the mechanical properties based on the tensile modulus to a predetermined ratio. For this reason, the fibers themselves do not need to have water absorption properties, so chemical material fibers are used for the fibers constituting the nonwoven fabric. Examples of chemical material fibers that can be used include polyester fibers, polyethylene fibers, polypropylene fibers, and acrylic fibers.

[0090] In this invention, even if the nonwoven fabric itself is made of fibers that do not absorb water, if it has a predetermined structure, it is possible to impart the property of preventing condensation from dripping to the nonwoven fabric. The industrial definitions of these fibers are described as follows in JIS L O204-2 (2001), which is the JIS standard for textile terminology (raw materials) Part 2: Chemical fibers. In this invention, since the three-dimensional structure of the nonwoven fabric is complex and does not have a regular structure, and it is difficult to directly quantitatively identify the three-dimensional structure of the nonwoven fabric, tensile modulus is used as an alternative parameter for evaluation.

[0091] Polyester fibers are fibers made of long-chain synthetic polymers containing 85% or more by mass of ester units of terephthalic acid and dihydric alcohols; polyethylene fibers are fibers made of long-chain synthetic polymers composed of saturated aliphatic hydrocarbons without substituents; polypropylene fibers are fibers made of stereoregular, long-chain synthetic polymers composed of saturated aliphatic hydrocarbons with one methyl group side chain for every two carbon atoms; and acrylic fibers are fibers made of linear synthetic polymers containing 85% or more by mass of repeating units of acrylonitrile groups.

[0092] Here, polyester fibers, polyethylene fibers, and polypropylene fibers do not absorb water, so even if water vapor is adsorbed onto the fiber surface, the fiber itself does not absorb water, resulting in no change in fiber strength and no decrease in strength due to water absorption. Acrylic fibers, however, experience a slight decrease in strength due to moisture absorption, but their wet-dry strength ratio is 0.9 or higher, and the decrease in strength is minimal compared to natural fiber materials such as rayon and vinylon. Therefore, there are no major problems when using acrylic fibers as a blended fiber with other non-absorbent fibers. In addition to polyethylene fibers, polypropylene fibers, polyester fibers, and acrylic fibers, the nonwoven fabric may contain certain amounts of natural fiber materials such as cellulose fibers, pulp, and rayon fibers. However, considering the decrease in strength due to moisture absorption of these fibers, their content should be kept within 30% of the total fiber weight. When using fibers such as cellulose fibers and pulp, it is desirable to use short fibers.

[0093] (Composition and structure of nonwoven fabric fibers) In this invention, the nonwoven fabric can be made of multiple fibers. For example, polyethylene fibers can be used in combination with PET fibers, or polyethylene fibers and polypropylene fibers. When polyethylene fibers are used in combination with PET fibers or polypropylene fibers in this way, the number of fusion points where the fibers fuse together can be easily controlled because the multiple fibers are mixed in a predetermined ratio. This makes it easier to obtain a predetermined three-dimensional structure in the fibers, and makes it easier to obtain a stable nonwoven fabric even with a high porosity. The advantage of using multiple fibers or fibers with a core-sheath structure is that it is possible to selectively fuse the fibers together by utilizing the difference in melting points of different resins.

[0094] As for nonwoven fabric fibers, in addition to using a mixture of two types of fibers, nonwoven fabrics using fibers with a core-sheath structure can be used. The advantage of using such core-sheath fibers in nonwoven fabrics is that when fusing the fibers together, for example, by using PET fibers or polypropylene fibers in the core and polyethylene fibers in the sheath, it becomes possible to fuse the fibers together at a relatively low temperature of 120-140°C, making it easier to manufacture nonwoven fabrics. At the same time, by using higher-strength fibers in the core than in the sheath, the rigidity of the fibers used in the nonwoven fabric can be increased, which makes it possible to reduce the fiber diameter of the fibers constituting the nonwoven fabric, and makes it easier to control the porosity of the nonwoven fabric.

[0095] Nonwoven fabrics are constructed by using multiple fibers with different melting points, melting the fibers with lower melting points, and using them as a binder. When PET fibers and polyethylene fibers are mixed and used in a predetermined ratio, the polyethylene fibers act as the binder. For example, if PET resin is used as the main constituent fiber, copolymerized polyester (Co-PET) resin, polypropylene resin, polyethylene resin, etc., can be used as the low-melting-point binder. This structure makes it easier to control the porosity and strength of the nonwoven fabric; for example, a nonwoven fabric with a predetermined strength can be obtained even with a high porosity.

[0096] Here, the nonwoven fabric of the present invention can also be a nonwoven fabric using fibers that combine fibers with a core-sheath structure having different melting points with other fibers. For example, by using a higher-strength fiber in the core than in the sheath, the rigidity of the fibers used in the nonwoven fabric can be increased. At the same time, by using high-strength fibers or hollow fibers in the other fibers and controlling the mixing ratio of the two, it becomes possible to improve the mechanical properties of the nonwoven fabric or impart flexibility to the nonwoven fabric.

[0097] Furthermore, when long fibers are used as the nonwoven fabric fibers of the present invention, the fibers tend to orient in the MD direction, which is the main direction during nonwoven fabric manufacturing. As a result, the mechanical properties in that direction tend to be more rigid than those in the TD direction. However, by using short fibers, it is possible to mitigate the influence of fiber orientation on the MD direction and improve orientation in the TD direction, thereby improving anisotropy. It is also presumed that similar effects can be obtained by using orthogonal warp and weft nonwoven fabrics or diagonal warp and weft nonwoven fabrics.

[0098] Furthermore, there are orthogonal nonwoven fabrics that can reduce the influence of the orientation of the fibers in the MD and TD directions, even without using short fibers. Orthogonal nonwoven fabrics are nonwoven fabrics in which the warp webs and weft webs are laminated and bonded in a perpendicular manner. In orthogonal nonwoven fabrics, the warp webs and weft webs are laminated perpendicularly using a laminating machine, and then these warp webs are stretched longitudinally, while the weft webs are stretched transversely. In addition to the above, there are oblique nonwoven fabrics which add an oblique nonwoven fabric to the orthogonal nonwoven fabric. In this way, by using orthogonal nonwoven fabrics or oblique nonwoven fabrics, even if a nonwoven fabric is made using long fibers instead of short fibers, the influence of the fiber orientation can be reduced, and the same effect as in the case of nonwoven fabrics using short fibers can be obtained.

[0099] By using a nonwoven fabric that satisfies the structural characteristics of the condensation drip-preventing heat-insulating material of the present invention, such as fiber diameter, porosity (filling rate), and presence or absence of bent fiber sections, the condensation drip-preventing properties are not affected, there is no need to use a water-absorbing resin, and the thickness of the nonwoven fabric can be 1.0 mm or more, but even with a thickness of 1.0 mm or less, the condensation drip-preventing properties and the embossing properties described later can be satisfied.

[0100] (Method of manufacturing nonwoven fabrics) Next, let's look at the manufacturing method of nonwoven fabrics. Nonwoven fabrics are typically formed by creating a thin, membrane-like sheet called a web, which is composed solely of fibers, and then joining the individual fibers forming the web together as needed.

[0101] There are various methods for forming nonwoven fabrics. For example, there are both wet and dry methods for forming the web. The wet method involves forming the fibers into a nonwoven fabric in a manner similar to that of papermaking. As will be described later, there are various methods for forming the web in the dry method, and the web can be formed by any of these methods. However, for the application of this invention to prevent condensation from dripping, when using long fibers, it is necessary to bend the fibers to form a three-dimensional structure of the nonwoven fabric. Therefore, it is desirable that the fibers of the nonwoven fabric have crimpability that allows them to bend.

[0102] Furthermore, to obtain a nonwoven fabric from a web, it is necessary to bond the fibers forming the web at predetermined positions. Various methods exist for bonding the fibers in the web, including chemical bonding methods such as immersion and spraying, thermal bonding, spunbonding, meltblowing, meltplane, airlay, spunlace (water-exchange method), and needle punching. Methods for forming nonwoven fabrics using long fibers include the chemical bonding, thermal bonding, spunbonding, meltblowing, and meltplane methods listed below. Methods for forming nonwoven fabrics using short fibers include the chemical bonding, thermal bonding, airlay, spunlace, and needle punching methods. Note that chemical bonding, thermal bonding, airlay, and spunlace methods can be used for both long and short fibers.

[0103] To explain each method in detail, the chemical bonding method is a method of partially bonding the web with an adhesive, the thermal bonding method is a method of bonding fibers together by mixing low-melting-point heat-fusible fibers and passing them between hot rolls for heat compression, or by applying hot air to melt the fibers and bond the heated parts of the fibers together, thereby bonding the fibers to each other, the spunbond method is a method of arranging fibers directly connected to the spinning process and forming a fabric using self-fusing heat, the meltblown method is a method of arranging fibers directly connected to the spinning process and intertwining ultrafine fibers, and the meltblown method is a method of melting resin and using high-temperature air sprayed from around the spinning nozzle to thin the fibers and accumulate them in a sheet form.

[0104] The air-lay method is a method of creating nonwoven fabric by bonding pulp with air and a binder. The spunlace method is a method of entangling fibers with a high-pressure water jet. The needle punch method is a method of producing nonwoven fabric by repeatedly piercing the web with a special needle that moves up and down at high speed, and entangling the fibers with protrusions formed on the needle.

[0105] In particular, in the present invention, it is sufficient for the nonwoven fabric to have structural characteristics such as a predetermined fiber diameter and a predetermined porosity. Therefore, as long as a nonwoven fabric that satisfies these structural characteristics can be obtained, there are no restrictions on the method of manufacturing the nonwoven fabric. Any method of manufacturing is acceptable as long as the nonwoven fabric has a predetermined porosity within the predetermined fiber diameter range used in this application, has crimpability such that the effective stress value at 5% elongation in a tensile test satisfies a predetermined value, and can be used for the purposes of the present invention.

[0106] In this invention, when the nonwoven fabric is manufactured using short fibers, chemical bonding, thermal bonding, air-laying, spunlace, and needle punching methods are often used. When using nonwoven fabrics made with such short fibers, it is expected that the difference in the orientation of the fibers in the MD direction and TD direction can be reduced compared to when using nonwoven fabrics made with long fibers. Therefore, it is possible that the differences in the mechanical properties of the nonwoven fabric can also be reduced.

[0107] Furthermore, there are orthogonal nonwoven fabrics that can reduce the influence of the orientation of the fibers in the MD and TD directions, even without using short fibers. Orthogonal nonwoven fabrics are nonwoven fabrics in which the warp webs and weft webs are laminated and bonded in a perpendicular manner. In orthogonal nonwoven fabrics, the warp webs and weft webs are laminated perpendicularly using a laminating machine, and then these warp webs are stretched longitudinally, while the weft webs are stretched transversely. In addition to the above, there are oblique nonwoven fabrics which add an oblique nonwoven fabric to the orthogonal nonwoven fabric. In this way, by using orthogonal nonwoven fabrics or oblique nonwoven fabrics, even if a nonwoven fabric is made using long fibers instead of short fibers, the influence of the fiber orientation can be reduced, and the same effect as in the case of nonwoven fabrics using short fibers can be obtained.

[0108] (Method for laminating nonwoven fabric to polyethylene-based resin foam) By placing a nonwoven fabric on one surface of a polyethylene resin foam and performing hot roll molding, the nonwoven fabric and the polyethylene resin foam can be fused together. Alternatively, by applying an adhesive to one surface of the polyethylene resin foam and then performing hot roll molding with the nonwoven fabric placed on the surface of the polyethylene resin foam, the nonwoven fabric can be fixed to the surface of the polyethylene resin foam.

[0109] (Embossing method) For example, a material in which a nonwoven fabric is fused to one surface of a foam can be heated to a predetermined temperature using an infrared heater, and then embossed by passing it through a pair of upper and lower embossing rolls.

[0110] When performing embossing, the surface of the material passing through the embossing roll is heated to a predetermined temperature, for example, 120-150°C, using an infrared heater. The embossing roll itself is cooled to maintain a predetermined surface temperature, for example, 20°C, to prevent adhesion of the nonwoven fabric or other material passing through the roll to the roll surface. By heating the material and cooling the roll in this way, it is possible to prevent the nonwoven fabric bonded to the surface from burning onto the material.

[0111] Furthermore, the raised and recessed patterns used for embossing are not particularly restricted and can be any shape as long as they can be formed, but in the case of the present invention, the bottom surface is approximately 4.0 mm. 2 ×Top surface 2.5mm 2 Embossing is performed to create a pyramidal square pattern with a height of approximately 1.2 mm across the entire width of the product, such that each side of the pyramidal square aligns with the MD direction and the TD direction, respectively.

[0112] During the embossing process, the nonwoven fabric itself is heat-molded, so while some deformation strain affects the three-dimensional structure, the effect is not very significant, and differences in structural characteristics between test materials are maintained. However, compared to unembossed materials, the embossing process makes the condensation resistance less effective, so the condensation resistance test after embossing is relatively more rigorous than the test for unprocessed materials. If no condensation drips from the embossed product during the condensation resistance test, it means that no condensation drips from the unprocessed product. [Examples]

[0113] (Measurement method) In the following examples, since the heat-insulating material of the present invention is composed of a resin foam and a nonwoven fabric, various heat-insulating materials with different compositions and structures of nonwoven fabrics and foams were used, and the presence or absence of condensation water dripping in condensation evaluation tests and the embossability of the heat-insulating material were evaluated before and after embossing. Here, since the structure of the nonwoven fabric is considered to have a large influence on condensation properties and embossability, the parameters used to determine the structure of the nonwoven fabric were fiber diameter, packing density, porosity, determination of the effective stress value at 5% elongation in a tensile test, and evaluation of water retention. In addition, structural observation of the nonwoven fabric fibers by SEM and optical microscopy observation of the nonwoven fabric after water absorption were performed as needed.

[0114] (Measurement and evaluation method for nonwoven fabrics) This document describes measurement and evaluation methods for the structural evaluation of nonwoven fabrics, including methods for measuring fiber diameter, nonwoven fabric thickness, porosity, and packing density, methods for measuring effective tensile stress values ​​by tensile tests, and methods for observing nonwoven fabrics using SEM and optical microscopes. It also explains performance evaluation methods related to the condensation properties of nonwoven fabrics, such as measuring water retention capacity. Furthermore, in addition to nonwoven fabric performance evaluation tests, condensation properties and embossing properties of thermal insulation materials were evaluated, and these methods will be described in detail.

[0115] (Non-woven fabric thickness) The nonwoven fabrics used in the test had thicknesses ranging from 0.22 mm to 0.95 mm. The thickness of the nonwoven fabrics used in the test was measured according to the JIS method using a nonwoven fabric thickness measuring instrument (φ56.4 mm disc flat measuring probe) capable of the same measurement method as Method A described in JIS General Nonwoven Fabric Measurement Method (JIS L1913:2010).

[0116] (Fiber diameter) The fiber diameter of the nonwoven fabric was calculated by selecting 20 arbitrary locations from the fiber images obtained by SEM and using image processing software to determine the average fiber diameter (numerical average). Here, the average fiber diameter of the nonwoven fabric used in this invention is in the range of 10 μm to 30 μm, and fibers in this range are commonly used for nonwoven fabrics. The reason for this is that although it is possible to manufacture nonwoven fabric with a fiber diameter of 10 μm or less, the strength of the nonwoven fabric is insufficient at a fiber diameter of 10 μm or less, resulting in reduced durability when used on the surface of a protective member. Furthermore, if the fiber diameter exceeds 30 μm, the filling rate of the nonwoven fabric increases relatively due to the increase in the diameter of the nonwoven fabric, making it difficult to maintain the void ratio in the range of 85 to 98%. Therefore, it is desirable for the average fiber diameter to be in the range of 10 to 30 μm. Note that in each test material of each embodiment, the measured fiber diameter of each test material is described as fiber diameter for simplification, but these measured fiber diameters represent the average fiber diameter.

[0117] (porosity, filling rate) The porosity of the nonwoven fabric was calculated using the following formula, based on the apparent specific gravity determined by the thickness and basis weight of the nonwoven fabric. The true specific gravity used in calculations such as porosity was determined by the water displacement method. Here, the unit of porosity is volume percent. Porosity (%) = {1 - (Apparent specific gravity / True specific gravity)} × 100 Filling rate (%)=100-Porosity rate (%)

[0118] (Measurement of effective tensile stress in tensile tests) It is difficult to evaluate the crimpability, which indicates the degree of entanglement or bending of nonwoven fibers, and the influence of fiber joints for each individual fiber, and then translate these into macro-parameters of the overall nonwoven structure. Therefore, for each nonwoven, parameters related to elongation and stress in tensile tests were evaluated as surrogate parameters for evaluating the three-dimensional structure of the nonwoven fibers. To ensure water retention, an evaluation parameter related to porosity was obtained by dividing the stress value at 5% elongation in the tensile test by the packing density, i.e., the effective tensile stress value at 5% elongation was measured and evaluated as a value normalized by the packing density.

[0119] The behavior of elongation and stress change in the tensile test, as demonstrated in this study, affects not only water retention but also embossability. Since it is desirable for both to exhibit a large elongation in the tensile test and a small increase in stress in the low-strain region, these behaviors were confirmed through tensile testing. Furthermore, considering the winding strain on the refrigerant pipe, in the TD direction, the winding strain on the refrigerant pipe is added in addition to the embossing strain. Therefore, it was considered desirable for the elongation in the TD direction to be larger than the elongation in the MD direction and for the stress increase in the tensile test to be smaller.

[0120] Here, the effective stress values ​​were measured only in the MD direction because the TD direction is perpendicular to the direction of the nonwoven fabric's web, resulting in fewer joints and entanglements between fibers per predetermined length, making it difficult to stably measure strain with a strain gauge. Furthermore, it was found that the stress rise was lower in all nonwoven fabrics compared to the MD direction. Therefore, it was difficult to determine the effective stress value at 5% elongation in the TD direction, and it was determined that the water retention and condensation drip prevention properties of the nonwoven fabric would be affected by the evaluation parameters in the tensile behavior in the MD direction. Thus, priority was given to determining the effective stress value at 5% elongation in the MD direction. As will be described later, in Example 3 of the first embodiment, short-fiber nonwoven fabrics and warp-and-tip diagonal nonwoven fabrics were created with improved effective tensile stress in the TD direction. For some materials, in addition to the effective tensile stress value in the MD direction, the effective tensile stress in the TD direction was also determined.

[0121] Furthermore, the reason for determining the effective stress value of the nonwoven fabric to be the effective stress value at 5% elongation is that, based on the results of preliminary tests, measuring the stress value at 2% elongation would involve measuring a minute deformation region, and in addition to the uniformity of the nonwoven material, there would be variability in the accuracy of the strain amount during measurement, making it impossible to guarantee precision. Moreover, the effective tensile stress level would be small, making it difficult to discern differences between each material. On the other hand, at 10% elongation, there is a possibility of applying deformation to a stress level region where the effects of differences in the three-dimensional structure of the fibers within the nonwoven fabric, as well as macro-structural changes due to state changes such as engagement, friction, and fusion between the fibers of each nonwoven fabric, and secondary state changes of the nonwoven fabric accompanying the progression of tensile deformation become apparent, making it possible that the three-dimensional structure as the initial state of the nonwoven fabric cannot be correctly evaluated. Therefore, the effective stress value at 5% elongation was considered an appropriate parameter to indirectly represent the structure of the nonwoven fabric.

[0122] A JIS K6251(2017) No. 1 dumbbell-shaped test specimen was punched out from each nonwoven fabric in the MD direction. The sample was held with a chuck distance of 80 mm, the gauge length was set to 40 mm, and a tensile test was performed at 10 mm / min. The effective tensile stress was measured when the strain between the gauges reached 5%, and this value was divided by the fiber filling density of the nonwoven fabric to express the normalized effective stress value at 5% elongation as the effective tensile stress value at 5% elongation. To account for the variability of this effective tensile stress value, the test was performed three times for each material, and the average value was defined as the effective tensile stress value for each material.

[0123] (SEM and optical microscope observation of nonwoven fabrics) To confirm the degree of bending and entanglement structure of the fibers constituting the nonwoven fabric, a scanning electron microscope (SEM) was used to observe representative examples of nonwoven fabrics that exhibited condensation drip prevention and those that did not, at an acceleration voltage of 20 kV and 100x magnification. In addition, to confirm the water retention state of the nonwoven fabrics that exhibited condensation drip prevention, an optical microscope was used to observe the same material as that used for SEM observation, at the same magnification of 100x as the SEM observation, in a state where the nonwoven fabric was retaining water.

[0124] Here, the water absorption operation of the test piece for confirming the water retention state of the non-woven fabric with an optical microscope was carried out according to the following procedure. First, a non-woven fabric with a size of 30 mm × 30 mm was cut out, immersed in a beaker filled with water for more than 2 minutes, and sufficiently water-retained. Then, the sample was lifted with tweezers, waited until the water droplets stopped dripping, and further held the sample in contact with the edge of the beaker for 30 seconds. This was placed on the sample stage of the microscope, and measurement with an optical microscope was performed.

[0125] (Water retention amount) A non-woven fabric with a certain area was cut out from each non-woven fabric used in the test and weighed. Then, this non-woven fabric was immersed in tap water, allowed to sufficiently absorb water, lifted for more than 30 seconds until no water droplets fell, and then weighed again. The water retention weight was divided by the area to calculate the water retention amount per unit area (m 2 ) and is defined as the water retention amount (g / m 2 ). Since the non-woven fabrics used in the test had different non-woven fabric thicknesses, the comparison of the water retention amounts between the non-woven fabrics was made by converting the water retention amounts to those at a predetermined non-woven fabric thickness of 1 mm. The water retention amounts on the left side of Tables 1 to 3 are the measured water retention amounts, and the water retention amounts on the right side indicate the converted water retention amounts g / (m·mm) at a non-woven fabric thickness of 1 mm.

[0126] (Condensed water dripping prevention evaluation test) Figure 1 shows the setup for a condensation test using a constant temperature and humidity chamber. As shown in Figure 1(a), the condensation test involved wrapping four pieces of each condensation-preventing insulation material, which consists of a resin foam with a nonwoven fabric fused to its surface, around a stainless steel pipe serving as a refrigerant pipe, with the surface of each material facing outwards, and placing them inside a constant temperature and humidity chamber 1. For the test, a refrigerant pipe (stainless steel pipe) 2 with dimensions (outer diameter 49φ × inner diameter 45φ × wall thickness 2mm) was used as the refrigerant pipe. Various types of insulation materials 3 were prepared, each consisting of a foam with a foaming ratio of 30 times and a thickness of 10mm, with a nonwoven fabric fused to one surface. These materials were cut to a length of 150mm and wrapped around the entire circumference of the refrigerant pipe 2. For each test material, both embossed and unembossed versions of the insulation material 3 were used. In the following, the constant temperature and humidity chamber may be simply referred to as a constant temperature chamber.

[0127] For the test, after completing the preparations described above, the constant temperature chamber was maintained at 23°C and 50% RH humidity for 3 hours. Then, a 5°C refrigerant was flowed through the stainless steel tube 2, raising the temperature to a test temperature of 35°C and 90% RH humidity over 30 minutes. After that, the insulation material to prevent condensation dripping was maintained for 12 hours, and the presence or absence of condensation was evaluated by placing a drip sensor 5 directly below each test piece. During the test, the temperature outside the refrigerant tube was checked at point A, the surface temperature of the nonwoven fabric at point B, and the ambient temperature inside the constant temperature chamber at point C. The measured temperatures at points A, B, and C were controlled to within ±0.5°C of the set temperature.

[0128] Furthermore, the temperature inside the constant temperature chamber was confirmed by measuring the temperature using thermocouples placed in the positions shown in the diagram. Thermocouples were used to measure the ambient temperature inside the constant temperature chamber, the surface temperature of the embossed nonwoven fabric, and the interface temperature between the stainless steel pipe and the polyethylene resin foam at multiple locations. The thermocouples were set so that the error in the measured temperature at the same measurement location was within ±0.5°C. In addition, four test specimens were placed inside the constant temperature chamber for each test specimen in Examples 1 to 3 described later, and the test to check for the presence or absence of condensation water dripping was repeated according to the number of test specimens. For this reason, the tray for measuring the presence or absence of condensation water dripping was placed corresponding to the position of each test specimen. If there were fewer than four test specimens, test specimens that were not to be measured were placed inside the constant temperature chamber to ensure that the test conditions were always the same. In the test results, specimens without condensation water dripping were marked with "○", and specimens with condensation water dripping were marked with "×".

[0129] Figure 1(b) is a cross-sectional view of the insulation material 3 surrounding the refrigerant pipe 2 in a condensation evaluation test when embossed. The insulation material 3 wrapped around the outer circumference of the refrigerant pipe 2 consists of a resin foam 7 and a nonwoven fabric 8. The nonwoven fabric 8 is placed on the outermost surface of the resin foam 7, and the nonwoven fabric 6 is embossed, creating an uneven surface with the embossed portion 9. Note that the nonwoven fabrics used in the test differed in thickness depending on the type of nonwoven fabric, as shown in Table 1. Figure 1(b) is a cross-sectional view showing a laminated structure in which a resin foam is placed around the outer circumference of a stainless steel pipe used as a refrigerant pipe during testing, and a nonwoven fabric is placed on the outermost circumference. The surface of the nonwoven fabric has been embossed to create an uneven surface.

[0130] (Embossibility) A material in which a nonwoven fabric is fused to one surface of a polyethylene resin foam is heated to a predetermined temperature using an infrared heater, and then passed through a pair of upper and lower embossing rolls, resulting in a bottom surface of approximately 4.0 mm. 2 ×Top surface 2.5mm 2Embossability was evaluated by performing an embossing process that created a pyramidal square pattern with a height of approximately 1.2 mm across the entire width of the product, with each side of the pattern aligned with the MD direction and TD direction, respectively.

[0131] Specifically, the embossing properties were evaluated by performing 10 evaluations each in the MD direction and the TD direction. The evaluation was based on whether the target shape could be consistently achieved. A circle (○) was used if the target shape was obtained in the evaluated embossed area, while a cross (×) was used if at least one area had surface deformation or other defects that prevented the target shape from being achieved, or if there was damage to the fibers forming the nonwoven fabric.

[0132] As embodiments of the present invention, the first embodiment shows the results of evaluation tests for the condensation water drip prevention performance and embossability of various heat-insulating materials in Tables 1 to 3, respectively. The second embodiment shows the results of applying the heat-insulating material of the present invention to various piping structures, and the third embodiment shows the results of applying the heat-insulating material of the present invention to building materials. Examples of application to building structures will be described in order for condensation water drip prevention structures for inorganic building materials, condensation water drip prevention structures for ducts, and condensation water drip prevention structures for corrugated metal roofs. Here, the ducts refer to air conditioning ducts, but since ducts are relatively large members formed in building structures, the present invention has decided to include the condensation water drip prevention structure for ducts in the embodiments of application examples to building structures. In addition, in each fiber constituting the nonwoven fabric of the test material in Examples 1 to 3 (Tables 1 to 3) of the first embodiment, fibers with a core-sheath structure are indicated in parentheses, with the left side of the parentheses representing the core and the right side representing the sheath. Typically, the fibers that make up the sheath have a lower melting point than the fibers that make up the core.

[0133] (First embodiment: Example 1) In this study, for all test materials, LDPE foam was used as the resin foam, foamed to a thickness of 10 mm at a foaming ratio of 30. Nonwoven fabrics 1 to 5, each with different fiber structures, were fused onto the LDPE foam to obtain the thermal insulation materials 1 to 5. The fusion of the nonwoven fabrics to the foam surface was performed by hot roll molding under the aforementioned conditions. Various tests were conducted to determine the nonwoven fabric structure, and condensation evaluation tests and embossing tests were performed to evaluate the influence of the nonwoven fabric structure on condensation and embossing properties. Table 1 lists the sources of the nonwoven fabrics used in the tests for reference.

[0134] In addition to test materials 1 through 5, a conventional thermal insulation material that generates condensation, consisting of a polyethylene film fused to the surface of a polyethylene resin foam, was also included in the test. The conventional material, with a film thickness of 80 μm, has no voids and can be described as having 100% filling and 0% voids; this was designated as conventional material 1.

[0135] Here, test material 1 is a PET fiber with a fiber diameter of 17.3 μm, a filling density of 16.2%, a void ratio of 83.8%, and low fiber bending; test material 2 is a PET fiber with a fiber diameter of 17.1 μm, a void ratio of 97.8%, and high fiber bending; test material 3 is a (PP / PE) / PET fiber with a fiber diameter of 19.4 μm, a void ratio of 95.4%, and high fiber bending; test material 4 is an acrylic / (PET / PE) fiber with a fiber diameter of 11.7 μm, a void ratio of 91.2%, and high fiber bending; and test material 5 is a PET / PE fiber with a fiber diameter of 18.9 μm, a void ratio of 97.6%, and high fiber bending. In this study, nonwoven fabric 1 of test material 1 had a void ratio not exceeding 85% and exhibited little bending, while non-shrinkable fabrics 2-5 of test materials 2-5 had fiber diameters in the range of 10-30 μm, void ratios in the range of 85-98%, and showed a relatively large number of bent fiber sections.

[0136] Here, test materials 1 and 2 are nonwoven fabrics made of ordinary PET fibers alone, test material 3 is specifically a nonwoven fabric made of composite fibers of PP / PE fibers with a core-sheath structure (a fiber with a core-sheath structure in which PP is the core material and the outside is covered with PE) and PET fibers, and test material 4 is a nonwoven fabric made of fibers with a core-sheath structure in which the outer circumference of the PET fiber is covered with PE fiber, similar to test material 3, and acrylic fibers. Test material 5 is a nonwoven fabric using a mixed fiber of PE fiber and PET fiber.

[0137] (Test results) Table 1 shows the test results for Example 1 in the first embodiment. According to the test results in Table 1, the results of the condensation drip prevention evaluation test after embossing showed that the insulation materials of Test Materials 2 to 5 showed good results with no condensation dripping, whereas Test Material 1 and the conventional material did experience condensation dripping. Looking at the relationship between the presence or absence of condensation dripping in the test materials and the structure of the nonwoven fabric, it was confirmed that condensation dripping does not occur in nonwoven fabrics with an average fiber diameter in the range of 10 to 30 μm, a porosity of 85 to 98% (filling rate of 2 to 15%), and an effective tensile stress of 25 MPa or less, which is the value obtained by dividing the apparent tensile stress in the MD direction at 5% by the filling rate. Specifically, the effective tensile stress values ​​of Test Materials 2 to 5 are in the range of 7.2 to 17.2 MPa. Nonwoven fabrics that do not exhibit condensation dripping were found to have many bent sections in the fibers and high crimpability, as confirmed by SEM observation described later. Furthermore, the water retention capacity of the nonwoven fabric that does not exhibit condensation is 500 g / m², calculated per 1 mm of apparent thickness. 2 The above conditions were met. The results of the condensation water drip test before embossing were the same as before embossing, and there was no effect of embossing on the condensation water dripping.

[0138] In contrast, test material 1, a nonwoven fabric in which condensation occurred, had a fiber diameter that satisfied the above range of 10-30 μm, but its porosity was less than 85% and its filling density exceeded 15%. The low porosity resulted in an effective tensile stress of 38.5 MPa, which is the apparent stress in the same direction at 5% divided by the filling density, far exceeding 25 MPa. Furthermore, the nonwoven fabric had few bent sections in its fibers, resulting in low crimpability. The amount of water that could not be prevented from dripping from the nonwoven fabric was 500 g / m², calculated per 1 mm of apparent thickness. 2 The criteria were not met. In summary, it was confirmed that nonwoven fabrics with a high porosity and a small effective tensile stress value at a predetermined strain of 5% elongation are superior in terms of condensation occurrence. Furthermore, although the fibers used in this test were non-absorbent synthetic fiber materials, it was considered that the drip-prevention property of the nonwoven fabric of the present invention is basically determined solely by its structure, regardless of the type of fiber.

[0139] Based on the results from Test Materials 1 to 5, it was found that even in the case of Test Materials 4 and 5, which are heat-insulating materials using fibers with a core-sheath structure, the water retention and condensation drip prevention properties correlate with the porosity of the fibers and the effective tensile stress, which is calculated by dividing the tensile stress at 5% elongation by the packing density. This correlation was observed regardless of whether the nonwoven fabric was made of a single fiber, a core-sheath structure, or a composite fiber made of two different materials.

[0140] The reason for these results is that when a nonwoven fabric is cooled below its dew point, in the case of a nonwoven fabric with high porosity, the fibers bend frequently and have crimpability. When cooled to a temperature below the dew point, numerous independent water films are formed in the three-dimensional network of fibers created by the high porosity nonwoven fabric, connecting the fibers and allowing a large amount of water to be retained within the nonwoven fabric. Conversely, when the porosity of the nonwoven fabric is small and the packing density is high, the space for water film formation is reduced due to the high packing density. The water film formation status is based on facts confirmed by optical microscopy.

[0141] Regarding embossing properties, test material 1, which had a high filling density, exhibited reduced embossing properties due to the high amount of fiber overlap, which could lead to nonwoven fiber breakage or instability of the embossed shape due to the elastic recovery of the fibers. Test materials 2 to 5, on the other hand, had an average fiber diameter of 10 to 30 μm and a high porosity of 85 to 98%, so there was no reduction in embossing properties due to fiber breakage or shape instability caused by fiber interaction due to fiber overlap.

[0142] As a result, if the nonwoven fabric structure has an average fiber diameter of 10-30 μm and a high porosity of 85-98%, and the nonwoven fabric thickness is 1.0 mm or less, and the effective tensile stress, which is the value obtained by dividing the tensile elongation in the MD direction at 5% by the packing density, is 25 MPa or less and 1 MPa or more, then the water retention of the heat-insulating material for preventing condensation dripping can be ensured regardless of whether or not it is embossed.

[0143] [Table 1]

[0144] (First embodiment: Example 2) Although it was thought that the composition of the foamed resin had little effect on the resistance to condensation dripping, in Example 2, experiments were conducted to confirm the effect of the composition of polyethylene-based resin foam on condensation properties and embossability using the resin composition and nonwoven fabric combinations shown in Table 2. In Example 2, the composition of the polyethylene-based resin foam was changed from LDPE to various polyethylene-based foams such as HDPE, a mixture of LDPE and HDPE, or EVA resin. Resin foams were prepared with carbon or titanium dioxide added as needed to improve heat resistance, or flame retardants added as needed to improve flame retardancy. Test materials 6 to 13 were prepared as insulation materials by fusing nonwoven fabric 2 or nonwoven fabric 4, which has excellent resistance to condensation dripping, to these resin foams. Also, as in Example 1, the foaming ratio of the foams used in these insulation materials was 30 times, and the foam thickness was 10 mm. The amounts of foaming agent and crosslinking agent were adjusted as appropriate within the above range.

[0145] The heat-insulating material for test material 6 is HDPE resin foam, test material 7 is a mixed resin of LDPE and HDPE in a 6:4 ratio, and the heat-insulating materials for test materials 8 to 11 are foams made by adding various additives to the LDPE and HDPE mixed resin. Specifically, the heat-insulating material for test material 8 has 0.5 parts by mass of carbon added to the mixed resin, test material 9 has 2.0 parts by mass of titanium dioxide added, test material 10 has 1.0 part by mass of antimony trioxide and 4.0 parts by mass of brominated flame retardant added, and test material 11 uses a resin foam with 20 parts by mass of magnesium hydroxide added. Furthermore, the heat-insulating material for test material 12 is EVA with 80 parts by mass of magnesium hydroxide added, and the heat-insulating material for test material 13 is EVA with 50 parts by mass of aluminum hydroxide added. Here, nonwoven fabric 2 made of PET fibers was used as the heat-insulating material for test materials 6 to 11, while nonwoven fabric 4 made of acrylic / (PET / PE) fibers was used for test materials 12 and 13.

[0146] (Test results) Table 2 shows the test results for Example 2. From the test results in Table 2, it can be seen that for all of the insulation materials from Test Material 6 to Test Material 13, the condensation drip prevention test in a constant temperature bath showed no effect from the foam composition, and no condensation drip occurred. Furthermore, the embossing properties were also good. Therefore, it is considered that for all of the insulation materials in Example 2, if the nonwoven fabric fused to the surface of the polyethylene resin foam satisfies the predetermined fiber diameter of 10-30 μm and predetermined porosity of 85-98% confirmed in Example 1, and satisfies the stress normalized by the filling rate at 5% elongation to 25 MPa or less, the condensation drip prevention properties will be satisfied regardless of the resin composition of the foam. In addition, the thickness of the nonwoven fabric used for the insulation material was 1 mm or less, and the water retention capacity per 1 mm of nonwoven fabric thickness was satisfied to 500 g / (m.mm). These insulation materials also had no problems with embossing properties, similar to Example 1.

[0147] [Table 2]

[0148] (First embodiment: Example 3) Table 3 shows the results of a test conducted to identify and search for materials that can satisfy not only the requirement that the effective tensile stress (the value obtained by dividing the apparent stress in the MD direction by the packing density at 5%) is 25 MPa or less and 1 MPa or more, but also that the effective tensile stress (the value obtained by dividing the apparent stress in the TD direction by the packing density at 5%) is 25 MPa or less and 1 MPa or more, respectively. The purpose of this test was to confirm the differences in the condensation drip prevention characteristics of condensation drip prevention insulation materials by ensuring that the effective tensile stress (the value obtained by dividing the apparent stress by the packing density) satisfies the predetermined value of 25 MPa or less and 1 MPa or more, regardless of the direction of the tensile test. For reference, Table 3 also lists the sources of the nonwoven fabrics used in the test.

[0149] Table 3 shows the test results for test materials 14-19. Test materials 14-16 are nonwoven fabrics made of long fibers oriented in the MD direction, test materials 17 and 18 are nonwoven fabrics made of short fibers, and test material 19 is a nonwoven fabric made of long fibers arranged in a diagonal weft and warp direction. Test material 14 is a nonwoven fabric made of acrylic / (PET / PE) fibers with a fiber diameter of 11.7 μm, a porosity of 91.2%, and a high degree of fiber bending. Test material 15 is a nonwoven fabric made of PET / PE fibers with a fiber diameter of 18.9 μm, a porosity of 97.6%, and a high degree of fiber bending.

[0150] (Test results) Test material 14 is a nonwoven fabric consisting of core-sheath structure fibers, in which hollow PET fibers are coated with PE fibers on their outer circumference, and acrylic fibers. Test material 15 is a nonwoven fabric using a mixed fiber of PE fibers and PET fibers. Here, the non-shrinkable fabrics of test materials 14 and 15 satisfy the range of void ratio of 85 to 98% with a fiber diameter in the range of 10 to 30 μm, and exhibit a relatively large number of fiber bends.

[0151] Test material 14 is a nonwoven fabric made of long fibers of PET / PE fibers and acrylic fibers. The PET / PE fibers are the same material as test material 4 in Table 1, which is a core-sheath nonwoven fabric in which PET constitutes the core and PE constitutes the sheath. In addition to the case of test material 4, test material 14 also includes a test value of the effective tensile stress in the TD direction. In the tensile test of test material 14, the tensile elongation values ​​in the MD direction and TD direction are 11.5 and 0.91 MPa, respectively, which are the effective tensile stress values ​​obtained by dividing the apparent stress in the same direction at 5% by the packing density. The fiber diameter is 11.7 μm and the fiber porosity is 91.2%. Therefore, the fiber diameter, porosity, and effective tensile stress in the MD direction all satisfy the requirement that the effective tensile stress in the same direction at 5% tensile elongation is 25 MPa or less and 1 MPa or more. However, the tensile elongation value in the TD direction does not satisfy the above range for the effective tensile stress in the same direction at 5% tensile elongation. In this case, the water retention capacity per 1 mm of nonwoven fabric is 700 g / m². 2 Furthermore, there was no dripping of condensation water before or after embossing, and the embossing performance was excellent.

[0152] Test material 15 is a nonwoven fabric made of long fibers with a core-sheath structure of PET / PE fibers, and is the same material as test material 5 in Table 1. The difference between test material 15 and test material 5 is that test values ​​for effective tensile stress in the TD direction are added. In the tensile test of test material 15, the tensile elongation values ​​in the MD direction and TD direction are 17.2 and 0.97 MPa, respectively, which are the effective tensile stress values ​​obtained by dividing the apparent stress in the same direction at 5% by the packing density. The fiber diameter is 18.9 μm and the fiber porosity is 97.6%. The fiber diameter and porosity satisfy the range of the present invention, and the effective tensile stress in the MD direction satisfies the range of the present invention, where the tensile elongation value in the MD direction satisfies the effective tensile stress in the same direction at 5% of 25 MPa or less and 1 MPa or more. However, the tensile elongation value in the TD direction does not satisfy the effective tensile stress in the same direction at 5% of 5%. In this case, the water retention capacity per 1 mm of nonwoven fabric is 1383 g / m 2 Furthermore, there was no dripping of condensation water before or after embossing, and the embossing performance was excellent.

[0153] Test material 16 is a nonwoven fabric made of long PET / PE fibers. In the tensile test of this test material 16, the tensile elongation values ​​in the MD and TD directions were 15.30 MPa and 2.10 MPa respectively, which are the effective tensile stress values ​​obtained by dividing the apparent stress in the same direction at 5% by the packing density. The fiber diameter is 17.0 μm and the fiber porosity is 95.6%. Thus, the fiber diameter, porosity, and effective tensile stress all satisfy the range of the present invention, which is an average fiber diameter of 10 to 30 μm, a fiber porosity of 85 to 98%, and an effective tensile stress of 25 MPa or less and 1 MPa or more in the same direction at a tensile elongation of 5% in both the MD and TD directions. In this case, the water retention capacity per meter of nonwoven fabric is 1303 g / m². 2 Furthermore, there was no dripping of condensation water before or after embossing, and the embossing performance was excellent.

[0154] Test material 17 is a nonwoven fabric made of short fibers with a core-sheath structure of PET / PE fibers. In the tensile test of test material 17, the tensile elongation values ​​in the MD and TD directions were 16.6 and 12.9 MPa, respectively, which are the effective tensile stress values ​​obtained by dividing the apparent stress in the same direction at 5% by the packing density. The fiber diameter is 20 μm and the fiber porosity is 97.2%. Therefore, the fiber diameter, porosity, and effective tensile stress all satisfy the range of the present invention, which is an average fiber diameter of 10 to 30 μm, a fiber porosity of 85 to 98%, and an effective tensile stress of 25 MPa or less and 1 MPa or more in the same direction at a tensile elongation of 5% in both the MD and TD directions. In this case, the water retention capacity per meter of nonwoven fabric is 937 g / m². 2 Furthermore, there was no dripping of condensation water before or after embossing, and the embossing performance was excellent.

[0155] Test material 18 is a nonwoven fabric made of short fibers of a composite of PET / PE fibers and pulp. In the tensile test of this test material 18, the tensile elongation values ​​in the MD and TD directions are 3.50 and 3.30 MPa, respectively, which are the effective tensile stress values ​​obtained by dividing the apparent stress in the same direction at 5% by the packing density. The fiber diameter is 18.3 μm and the fiber porosity is 91.1%. Thus, the fiber diameter, porosity, and effective tensile stress all satisfy the range of the present invention, which is an average fiber diameter of 10 to 30 μm, a fiber porosity of 85 to 98%, and an effective tensile stress of 25 MPa or less and 1 MPa or more in the same direction at a tensile elongation of 5% in both the MD and TD directions. In this case, the water retention capacity per meter of nonwoven fabric is 1247 g / m². 2 Furthermore, there was no dripping of condensation water before or after embossing, and the embossing performance was excellent.

[0156] Test material 19 is a nonwoven fabric made of long fibers having an oblique structure of PET / PE fibers. In the tensile test of this test material 19, the tensile elongation values ​​in the MD direction and TD direction are 8.89 and 4.41 MPa, respectively, which are the effective tensile stress values ​​obtained by dividing the apparent stress in the same direction at 5% by the packing density. The fiber diameter is 18.0 μm and the fiber porosity is 94.4%. Therefore, the fiber diameter, porosity, and effective tensile stress all satisfy the range of the present invention, which is an average fiber diameter of 10 to 30 μm, a fiber porosity of 85 to 98%, and an effective tensile stress of 25 MPa or less and 1 MPa or more in the same direction at a tensile elongation of 5% in both the MD and TD directions. In this case, the water retention capacity per meter of nonwoven fabric is 925 g / m². 2 Furthermore, there was no dripping of condensation water before or after embossing, and the embossing performance was excellent.

[0157] Here, the ratio of the effective tensile stress in the TD direction to the effective tensile stress in the MD direction, which is the apparent stress at the 5% tensile elongation of test material 14 and test material 15 divided by the packing density, is 0.08 and 0.06, respectively, indicating high anisotropy. The effective tensile stress in the TD direction of these materials is less than 1 MPa. In contrast, the ratio of the effective tensile stress in the TD direction to the effective tensile stress in the MD direction of test materials 16 to 19 is 0.14 to 0.94, indicating a small difference in effective tensile stress between the TD and MD directions, and the effective tensile stress in the TD direction exceeds 2 MPa in all cases.

[0158] Table 3 shows the results of whether condensation dripping occurs when the thermal insulation material of the present invention is applied to vertical and diagonal pipes and structures. When test materials 14 and 15 are used, the effective tensile stress in the TD direction is less than 1 MPa, and in the case of the usual construction method where the MD direction is aligned with the vertical direction, condensation dripping occurs, and therefore the evaluation result for condensation in vertical and diagonal structures is "×". On the other hand, when test materials 16-19 are used, the effective tensile stress in both the MD direction and the TD direction exceeds 1 MPa, so even when the thermal insulation material of the present invention is used on vertical and diagonal pipes and structures, condensation dripping does not occur, and the evaluation result for condensation prevention in vertical and diagonal structures is "〇". Furthermore, even with the thermal insulation materials of test materials 14 and 15, if the MD direction is aligned with the horizontal direction instead of the vertical direction during construction, the same effect as materials where the effective tensile stress in the MD direction and the TD direction exceeds 1 MPa is obtained, and condensation dripping does not occur.

[0159] As described above, it was confirmed that a nonwoven fabric with an average fiber diameter of 10-30 μm and a high porosity of 85-98%, with a nonwoven fabric thickness of 1.0 mm or less, satisfying an effective tensile stress of 25 MPa or less and 1 MPa or more in the MD direction in tensile tests, while also satisfying similar tensile properties in the TD direction, can be obtained not only when using short fibers in the nonwoven fabric, but also when using long fibers with an oblique structure, and that a heat-insulating material for preventing condensation dripping can be obtained using such a nonwoven fabric.

[0160] [Table 3]

[0161] (Second embodiment: Application of the heat-insulating material of the present invention to refrigerant piping and water supply / hot water supply piping structures) Next, as a second embodiment, various piping structures to which the heat-insulating material of the present invention is applied will be described. The following five types of piping structures will be described: a piping structure in which the heat-insulating material of the present invention is wrapped around the outer circumference of the pipe; a spectacle-type piping structure in which two pipes, each wrapped with the heat-insulating material around its outer circumference, are placed opposite each other and the opposing parts are heat-fused together; a cylindrical piping structure in which existing refrigerant piping is surrounded with the heat-insulating material of the present invention; a cylindrical piping structure in which existing water supply and hot water supply piping and its protective pipe are surrounded with the heat-insulating material of the present invention; and a piping structure in which the protective member of the present invention is applied to vertical piping.

[0162] (Second embodiment: Example 1) (A piping structure in which the heat-insulating material of the present invention is wrapped around the outer circumference of the refrigerant piping.) Figure 2(a) shows a perspective view of a piping structure in which a heat-insulating material 3 for preventing condensation dripping is wrapped around the outer circumference of a refrigerant pipe 2. Here, the piping in Figure 2(a) is a piping in which a heat-insulating material 3, which is made by fusing an embossed nonwoven fabric 8 and a polyethylene resin foam 7, is wrapped around the outer circumference of the refrigerant piping of a heat exchanger with the embossed portion 9 of the nonwoven fabric facing outwards and the resin foam surface in contact with the piping. The heat-insulating material 3 wrapped around the outer circumference of the refrigerant pipe 2 faces each other at the heat-sealed portion 11, and these opposing surfaces are fixed by heat sealing or adhesive. Figure 2(b) shows a cross-sectional view obtained by cutting the piping shown in Figure 2(a) at a predetermined position that includes a straight line XX that crosses it at a right angle. Inside the refrigerant pipe 2, a refrigerant at a predetermined temperature flows. The reason for positioning the embossed portion 9 so that it faces the outer circumference of the insulation material 3 is to facilitate deformation of the outer circumference in response to the difference in circumference between the inner and outer circumferences of the nonwoven fabric covering the refrigerant pipe 2.

[0163] (Second embodiment: Example 2) (A spectacle-type piping structure in which refrigerant pipes covered with the heat-insulating material of the present invention are integrated and face each other) Figure 3(a) shows a spectacle-shaped piping structure 10 in which pipes, each covered with a heat-insulating material 3 to prevent condensation dripping, are positioned opposite each other and integrated. In piping structures 10a and 10b, the heat-insulating material 3 wrapped around the outer circumference of the refrigerant pipe 2 faces each other at a heat-sealed joint 11, and these opposing surfaces are fixed by heat sealing or adhesive. Figure 3(b) shows a cross-sectional view of the piping structure cut at a predetermined position including a straight line AA that intersects the two pipes shown in Figure 3(a) at a right angle, with refrigerant at a predetermined temperature flowing inside the refrigerant pipe 2. The embossed portion 9 is positioned so that it faces the outer circumference of the heat-insulating material 3 in order to facilitate deformation of the outer circumference of the nonwoven fabric covering the refrigerant pipe 2.

[0164] The present invention provides a cylindrical pipe structure having a pair of spectacle-shaped cross-sections. This is achieved by partially heating and melting the area near the surface of the nonwoven fabric, which is the outer layer of the insulation material, of at least one of two pipes that have been wrapped around the outer circumference of the refrigerant piping of a heat exchanger to a predetermined temperature above the melting point of the nonwoven fabric, using hot air, a heating plate, ultrasound, a laser, etc., and then immediately heat-sealing or heat-compressing that portion.

[0165] Furthermore, the piping in Figure 3(a) can be made by placing the ends of the insulation material wrapped around the pipe (as shown in Figure 2(a)) opposite each other, pressing the opposing surfaces together, and heat-sealing them at a predetermined temperature. This allows for the creation of a spectacle-shaped piping structure in which nonwoven fabric is heat-sealed to the surface of a resin foam, and the insulation material is wrapped around the outer circumference of the pipe. In this case, the ends of the insulation material wrapped around the pipe can be fixed in place by heat sealing as described above, or by bonding with double-sided tape or the like.

[0166] Here, the smaller diameter pipe in the spectacle-shaped piping is the liquid refrigerant piping, and the larger diameter refrigerant piping is the gas piping. In this way, a piping structure can be obtained in which the heat-insulating material of the present invention is wrapped around the outer circumference of the refrigerant piping of the heat exchanger with the embossed surface of the nonwoven fabric facing outwards. By obtaining such a piping structure, condensation that occurs in conventional spectacle-shaped piping structures in which a heat-insulating material consisting of a polyethylene resin foam with a resin film such as polyethylene attached to its surface is wrapped around the piping can be prevented by using the spectacle-shaped piping structure of the present invention.

[0167] (Second embodiment: Example 3) (A cylindrical piping structure in which existing refrigerant piping is surrounded by the heat-insulating material of the present invention.) Figure 4 shows a cylindrical refrigerant piping structure 16 in which multiple refrigerant pipes, drain pipes, and wiring are surrounded by the insulating material of the present invention. This piping structure will now be explained. A typical example of this piping is a general heat exchanger piping, which includes two refrigerant pipes 2, a drain pipe 12, and wiring 13. The refrigerant pipes 2, drain pipe 12, and wiring 13 of the heat exchanger are combined, and the entire set of pipes and wiring is surrounded by a cylindrical insulating material 14 with the nonwoven fabric 25 formed surface facing the outer surface, and can be used to connect the indoor and outdoor units of the heat exchanger. In this case, both ends of the insulating material 3 surrounding the combined pipes and wiring can be fixed by heat fusion, double-sided tape, or other adhesives.

[0168] In conventional piping, the piping structure involves a resin foam sheet with a resin film laminated to the surface of each individual pipe as insulation, covering the outer circumference of the pipe. However, as in the present invention, a nonwoven fabric satisfying a predetermined fiber diameter, filling density, and tensile modulus as a mechanical property is fused to the surface of the resin foam, resulting in an insulation material that does not have the effect of preventing condensation from dripping. Therefore, although there is an insulating effect from the foam, even if the outer circumference of a set of pipes, such as the piping of multiple existing heat exchangers or drain pipes and wiring, is covered, it is not possible to prevent condensation from dripping from the insulation material.

[0169] The entire cross-section of this set of pipes and wiring can be enclosed in a cylindrical pipe structure with the nonwoven fabric surface of the sheet-like heat-insulating material of the present invention facing outwards. In this case, by enclosing the outer periphery of the pipes and wiring, including the drain pipe, in a cylindrical shape with the nonwoven fabric facing outwards, it is possible to prevent condensation from forming on the outer periphery of the pipes.

[0170] (Second embodiment: Example 4) (A cylindrical piping structure in which existing water supply and hot water supply pipes and their protective pipes are surrounded by the heat-insulating material of the present invention.) Furthermore, the piping structure enclosed in a cylindrical shape by the heat-insulating material of the present invention is not limited to refrigerant piping for heat exchangers as described above. As shown in Figure 5(a), a cylindrical piping structure 19a for water supply and hot water supply can be formed by placing the protective member of the present invention on the outer circumference of a resin sheath pipe 17, which is a protective pipe for the outer circumference of a cross-linked polyethylene pipe 15 used as water supply and hot water supply piping. Similar to the cylindrical piping structure for refrigerant in the heat exchanger described above, both ends of the cylindrical heat-insulating material 14 wrapped around the piping are fixed by heat fusion, adhesive such as double-sided tape, etc.

[0171] In conventional existing water supply and hot water supply piping, the piping structure consists of a corrugated resin sheath pipe 17, which serves as a protective tube, covering the outer circumference of the cross-linked polyethylene pipe 15, which is the water supply and hot water supply piping. However, the outer circumference of the water supply and hot water supply piping is not covered by a foam sheet 18. Furthermore, if only the resin sheath pipe 17 is used as a protective tube, condensation may occur on the outer surface of the sheath pipe 17, which is exposed to the outermost layer, depending on the usage environment. By surrounding the outer circumference of the resin sheath pipe in a cylindrical shape with the heat-insulating material of the present invention, it is possible to prevent condensation from occurring on the outer circumference of each pipe and the outer circumference of the wiring, and to prevent the dripping of condensation water from the outer circumference of the cylindrical piping structure.

[0172] By using the heat-insulating material of the present invention to create a cylindrical piping structure in which the outer circumference of a resin sheath pipe, which serves as a protective pipe for water supply and hot water supply piping, is surrounded in a cylindrical shape by the protective member of the present invention, it is possible to prevent the dripping of condensation water that would occur if the water supply and hot water supply piping were used in a harsh environment with only the sheath pipe covered.

[0173] Furthermore, Figure 5(b) may show a cylindrical piping structure 19b in which the outer circumference of the resin sheath pipe protecting the cross-linked polyethylene pipe shown in Figure 5(a) is covered with a cylindrical insulating material 14 coated with resin foam. Alternatively, the outer circumference of the resin sheath pipe protecting the cross-linked polyethylene pipe used as water supply and hot water supply piping, as shown in Figure 5(b), may be covered with resin foam 7, and the outer circumference of this resin foam 7 may be further covered with the cylindrical protective member 14 of the present invention to form a cylindrical piping structure. By adopting such a structure, condensation occurring on the outer circumference of the water supply and hot water supply piping can be prevented more reliably.

[0174] (Second embodiment: Example 5) (Piping structure and method for forming the same, applying the protective member of the present invention to vertical piping) In the case of pipes covered with the thermal insulation material of the present invention so that the MD direction coincides with the horizontal direction, no condensation dripping is observed. However, in the case of vertical pipes covered with the thermal insulation material so that the MD direction coincides with the vertical direction, a situation can be considered where both the suction effect due to surface tension and the sedimentation and dripping of condensation due to gravity compete. Experiments were conducted to confirm the presence or absence of condensation and other problems when the pipes of the present invention are used as vertical pipes.

[0175] Figure 6 shows a piping structure in which the protective member of the present invention is applied to vertical piping. Figure 6 shows a roughly U-shaped piping system in which vertical piping is provided approximately symmetrically on both sides of a horizontal pipe within a constant temperature and humidity chamber. In this piping system, a 25 cm left-side vertical pipe 20 is provided that descends vertically to the left of the central part of the horizontal pipe, passes through a horizontal pipe 22 of approximately 30 cm, and a 25 cm right-side vertical pipe 21 is provided that rises vertically to the right of the aforementioned horizontal pipe.

[0176] Figure 6 shows the piping structure, including the vertical pipes, in a verification experiment conducted using pipes with insulation wrapped around the vertical pipes 20 and 21 on the left and right sides. The entire piping was placed in a constant temperature chamber at 35°C and 90% humidity, and a refrigerant at a temperature of 5°C was circulated through the pipes to check for the presence or absence of condensation. In this experiment, the weight of the condensation in each pipe was measured by the change in weight of the tray 23 before and after the test, in which the condensation water 24 was collected in the tray 23 by placing the tray 23 at the bottom of the vertical pipe.

[0177] Insulation material X is an insulation material using a nonwoven fabric that satisfies the requirement of 25 MPa or less and 1 MPa or more for the effective tensile stress in the MD direction only in a tensile test. Insulation material Y is an insulation material for preventing condensation dripping that satisfies the requirement of 25 MPa or less and 1 MPa or more for the effective tensile stress in both the MD and TD directions.

[0178] As a result, when insulation material X was wrapped around a vertical pipe with its MD direction aligned with the vertical direction, dripping began 1 hour after being placed in the constant temperature bath, and 40.9 g of water dripped after 15 hours. In contrast, when insulation material Y was wrapped around a vertical pipe with its MD direction aligned with the vertical direction, no condensation dripped even after 15 hours after the insulation material was placed in the constant temperature bath. Here, insulation material X corresponds to test material 14 in Table 3, and insulation material Y satisfies test material 17 in Table 3.

[0179] Furthermore, when the insulation materials of test materials 17, 18, and 19 in Table 3 were similarly wrapped around vertical pipes, no condensation dripped. The reason for this is thought to be that, in the case of the insulation materials of test materials 16 to 19, the effective tensile stress in both the MD and TD directions satisfies the requirement of 25 MPa or less and 1 MPa or more. Therefore, the moisture retained by the nonwoven fabric moved and evaporated in the horizontal direction (TD direction), preventing condensation from forming. Thus, as an insulation material to cover vertical pipes, a vertical pipe structure that prevents condensation dripping can be obtained by covering the pipes with insulation material that satisfies the requirement of 25 MPa or less and 1 MPa or more in both the MD and TD directions.

[0180] Furthermore, in the case of a pipe in which a condensation drip-preventing insulation material is wrapped around the outer circumference of a refrigerant pipe, and the pipe is a vertical pipe, a method for forming a vertical pipe can be obtained characterized by arranging at least one direction in which the condensation drip-preventing insulation material satisfies an effective tensile stress of 25 MPa or less and 1 MPa or more in a horizontal direction perpendicular to the direction of the vertical pipe. In this way, by covering the pipe with an insulation material that satisfies an effective tensile stress of 25 MPa or less and 1 MPa or more in a horizontal direction, the same effect as when an insulation material that satisfies an effective tensile stress of 25 MPa or less and 1 MPa or more in the TD direction is used can be obtained, even without using an insulation material that satisfies an effective tensile stress of 25 MPa or less and 1 MPa or more in the TD direction, and it becomes possible to prevent condensation dripping. This is thought to be due to the effect of making it easier for condensation water adsorbed or retained by the nonwoven fabric to evaporate from the surface of the nonwoven fabric.

[0181] (Third embodiment: Application of the heat-insulating material of the present invention to a structure for preventing condensation water from dripping onto building components) As examples of the application of the heat-insulating material of the present invention to building components in a third embodiment, Examples 1 to 3 show a structure to prevent condensation from dripping in ducts, a structure to prevent condensation from dripping in inorganic building materials, and a structure to prevent condensation from dripping in corrugated metal roofs.

[0182] (Third embodiment: Example 1) (Duct condensation drip prevention structure and method for forming the same) Figure 7 shows a condensation drip prevention structure 30 for a duct body 29 using the heat-insulating material 3 of the present invention. A rectangular parallelepiped duct with a thickness of 25 cm, a length of 30 cm, and a height of 30 cm was created, and the surface of the foam 7 on the back of the heat-insulating material was bonded to the duct body 29 with an adhesive so that the nonwoven fabric forming surface of the heat-insulating material was positioned on the surface of the duct body 29. This created a structure in which the entire surface of the duct body 29 was covered with the nonwoven fabric 8 of the heat-insulating material. This structure was placed in a constant temperature and humidity chamber, and a refrigerant gas under the same conditions as in the case of the condensation drip prevention piping structure for vertical piping in Example 5 of the second embodiment was flowed into the duct to perform a condensation drip prevention test. As a result, the same results as in the case of vertical piping for refrigerant were obtained.

[0183] The results of this test showed that the dripping behavior of condensation water on the duct surface differed depending on the type of insulation material covering the outer surface of the duct. For example, when using insulation material that satisfied the effective tensile stress of 25 MPa or less and 1 MPa or more in both the MD and TD directions (test materials 16-19), it was confirmed that there was no dripping of condensation water from the outer circumference of the duct. Furthermore, when insulation material that satisfied the effective tensile stress of 25 MPa or less and 1 MPa or more in the MD direction only, and the effective tensile stress of 1 MPa or less in the TD direction only, as in test materials 14 and 15, was placed on the side of the duct with the MD direction facing upwards, dripping of condensation water was observed. When the insulation material of test materials 14 and 15 was formed on the side of the duct with the TD direction facing horizontally, no dripping of condensation water was observed. To prevent condensation from dripping from such ducts, a method for forming the duct structure can be used in which at least one direction in which the condensation drip-preventing insulation material satisfies an effective tensile stress of 25 MPa or less and 1 MPa or more is positioned in a horizontal direction perpendicular to the direction parallel to the vertical direction of the duct side wall.

[0184] (Third embodiment: Example 2) (Condensation drip prevention structure for inorganic building boards and method for forming the same) Figure 8(a) shows a horizontal condensation drip prevention structure 27 for inorganic building boards, in which a heat-insulating material for preventing condensation dripping is placed on the surface of the inorganic building board 26. In this case, the condensation drip prevention structure for inorganic building boards may also be such that the opposing surfaces of the heat-insulating material 3 for preventing condensation dripping and the inorganic building board 26 are bonded to each other. In the present invention, at least one of gypsum board or calcium silicate board can be used as the inorganic building board 26. The usage state in this case corresponds to the heat-insulating material portion on the upper surface of the duct in Example 1 of the third embodiment. For this reason, the nonwoven fabric used in the horizontal condensation drip prevention structure 27 for inorganic building boards, which is placed on the surface of the inorganic building board 26, does not need to consider the downward movement of condensation water due to gravity, so any nonwoven fabric that satisfies an effective tensile stress in the MD direction of 5% elongation in a tensile test of 25 MPa or less and 1 MPa or more is sufficient. This structure makes it possible to prevent condensation on the surface when gypsum boards and calcium silicate boards are arranged horizontally.

[0185] Figure 8(b) shows a vertical condensation drip prevention structure 28 for inorganic building boards 26, on which condensation drip prevention insulation material 3 is adhered to the surface, and which are arranged vertically as vertical walls. In this case, as can be seen from the experimental results for the duct in Figure 7, the nonwoven fabric insulation material that can be used for vertical wall structures does not satisfy the requirement that the effective tensile stress at 5% elongation in the MD direction in a horizontal wall structure is 25 MPa or less and 1 MPa or more. It is necessary to have a vertical wall structure on which insulation material is placed on the surface that satisfies the requirement that the effective tensile stress at 5% elongation in the MD and TD directions of the nonwoven fabric used for insulation material is 25 MPa or less and 1 MPa or more.

[0186] In this case, the effective tensile stress value of the nonwoven fabric used as a thermal insulation material for vertical walls, as a mechanical property in both directions, must satisfy the above constraints. This is because condensation water drips from the bottom of the thermal insulation material that is positioned vertically on the surface of the inorganic building board material. Therefore, it is necessary to create a nonwoven fabric structure that prevents condensation water from dripping by setting the effective tensile stress in the TD direction within a predetermined range, thereby accelerating evaporation from the surface of the nonwoven fabric by promoting movement to the sides of the nonwoven fabric. In addition to the above, in order to form a vertical condensation water drip prevention structure 28 for inorganic building board material 26 that is positioned vertically as a vertical wall, it is also possible to use a formation method that, similar to the case of ducts, positions at least one direction in which the effective tensile stress of the condensation water drip prevention thermal insulation material satisfies the condition of 25 MPa or less and 1 MPa or more, in a horizontal direction perpendicular to the direction parallel to the vertical direction of the inorganic building board material.

[0187] (Third Embodiment: Example 3 - Structure for preventing condensation dripping on a corrugated metal roof and method for forming the same) Figure 9 shows a structure 32 for preventing condensation from dripping onto a corrugated metal roof, in which a steel plate is folded and laminated with the nonwoven fabric 8 of the present invention's heat-insulating material 3 on the underside of the steel plate of the corrugated metal roof 31 with the underside facing downwards. The corrugated metal roof 31 is usually formed into a roughly repeating V-shape with the upper and lower edges having predetermined widths and slanted edges sandwiching the upper and lower edges. For example, one cycle forms a roof with a height of 160-180 mm and a width of approximately 500 mm.

[0188] For example, in a condensation test simulating use on a corrugated metal roof, a structure can be created by using a 0.8 mm thick galvalume steel sheet (registered trademark) and bonding an insulating material to it, which consists of a polyethylene resin foam with a nonwoven fabric that satisfies predetermined mechanical properties, thereby realizing a structure that prevents condensation water from dripping onto a corrugated metal roof.

[0189] Even when using the condensation drip prevention structure for the corrugated metal roof shown in Figure 9, if the difference in vertical height of the folded structure of the corrugated metal roof is taken into consideration, it is necessary to use insulation material that satisfies an effective tensile stress of 25 MPa or less and 1 MPa or more in both the MD and TD directions. When test materials 16 to 19 in Table 3 were used as actual roofing material, it was confirmed that there was no dripping of condensation water from the nonwoven fabric on the surface of the insulation material at the bottom of the corrugated metal roof.

[0190] Furthermore, when insulation materials were applied that satisfied the effective tensile stress of 25 MPa or less and 1 MPa or more only in the MD direction, as in test materials 14 and 15, but had an effective tensile stress of less than 1 MPa in the TD direction, condensation dripping was observed from the surface of the insulation material on the sloping lower part of the corrugated metal roof. Even with these insulation materials, dripping of condensation from the nonwoven fabric on the surface of the insulation material can be prevented by attaching it to the back surface of the corrugated metal roof in a direction perpendicular to the bending direction of the corrugated metal roof in the MD direction. Therefore, in order to obtain a structure that prevents condensation dripping on a corrugated metal roof, it is necessary to position at least one direction in which the effective tensile stress of the condensation drip-preventing insulation material that satisfies the condition of 25 MPa or less and 1 MPa or more is perpendicular to the bending direction of the corrugated metal roof, and a forming method that satisfies this is necessary.

[0191] Here, Figure 10(a) shows the results of SEM observation at 100x magnification of nonwoven fabric 4, a representative example of a nonwoven fabric with excellent resistance to condensation dripping, as a representative example of a material in which no condensation dripping occurred during the condensation confirmation test. It can be seen that nonwoven fabric 4 has a structure with many bends and high crimpability. Although not shown in particular, it was found that nonwoven fabric 1, which was used in test material 1 where condensation dripping occurred, has relatively few bends and low crimpability. Furthermore, Figure 10(b) shows the results of observation of the nonwoven fabric 4, which has excellent resistance to condensation dripping, at 100x magnification after water absorption. From this photograph, it can be seen that a water film is formed connecting the three-dimensional structure of the bends in the fibers of the nonwoven fabric, and as a result the nonwoven fabric retains the condensation water. Figure 10(c) shows a 100x SEM image of the nonwoven fabric made of diagonally intersecting fibers of test material 19. Compared to Figure 10(a), this image shows that the horizontal fiber flow (corresponding to the TD direction) in the field of view is stronger. Figure 10(d) shows the case of a nonwoven fabric using short fibers, corresponding to test material 18. In this case as well, it can be seen that the horizontal fiber flow in the field of view is improved compared to Figure 10(a). As a result, even when the MD direction of the heat-insulating material is aligned with the vertical direction and used in a structure with a large vertical component using normal usage methods, the movement of water retained on the fiber surface and in the intertwined parts of the fibers towards the TD direction is promoted, which leads to homogenization within the nonwoven fabric. This promotes the evaporation of retained water, suppresses the aggregation of condensation water on the lower fibers, and as a result, prevents condensation water from dripping. Here, the pulp fibers in the field of view appear to have a fiber diameter of about 40 μm, but because the pulp fibers are crushed and beaten, the fiber thickness is 10 μm or less, and the average fiber diameter of the pulp (average of the dimensions in the width direction and thickness direction of the pulp), taking into account the aspect ratio, is 30 μm or less, which generally satisfies the range of fiber diameter in this application.

[0192] In summary, the present invention has confirmed that by providing a predetermined structure for the nonwoven fabric fused to the surface of the heat-insulating material, a heat-insulating material for preventing condensation dripping, a piping structure for preventing condensation dripping using the same, a structure for an air conditioning duct for preventing condensation dripping, a corrugated metal roof structure for preventing condensation dripping, and a nonwoven fabric used for the heat-insulating material for preventing condensation dripping can be obtained. Furthermore, observation of SEM images of Example 4, which exhibits excellent condensation drip prevention, reveals that a water film is formed connecting the three-dimensional structure of the nonwoven fabric fibers, resulting in the nonwoven fabric retaining the condensation water.

[0193] Furthermore, while this invention describes a method for forming vertical structures such as vertical piping and structures for preventing condensation from dripping onto building components, it is also possible to describe a method for using thermal insulation material in these vertical piping and structures for preventing condensation from dripping onto building components.

[0194] In addition to the above, we conducted several tests, including a water absorption rate measurement test in which 2.5 μml (1 drop) of tap water was dropped onto the nonwoven fabric and the time it took for the water to soak in was measured; a water absorption length measurement test in which a piece of nonwoven fabric of a predetermined size was cut out, the tip of which was immersed in water for 30 seconds and the length that rose up the fabric was measured; and a test to determine the water propagation velocity (cm / min / 0.3 mL) over 60 seconds on a 23.5° inclined plastic (acrylic) plate surface using a strip of nonwoven fabric of a predetermined size. However, none of these tests showed a correlation with condensation.

[0195] Although embodiments of the present invention have been described above with reference to the attached drawings, the technical scope of the present invention is not limited to the embodiments described above. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these will naturally also fall within the technical scope of the present invention. [Explanation of Symbols]

[0196] 1. Constant temperature bath 2. Refrigerant pipes (stainless steel pipes, copper pipes) 3. Heat insulation material 4. Temperature measurement point 5. Droplet sensor 6. Refrigerant 7. Resin foam 8. Nonwoven fabric 9. Embossed section 10.Glasses type piping structure 10a, 10b Piping structure 11. Heat-fused joint 12. Drain pipe 13. Wiring 14. Cylindrical insulation material 15. Cross-linked polyethylene pipe 16.Cylindrical piping structure for refrigerant 17.Resin sheath tube 18. Foam 19a, 19b: Cylindrical piping structure for water supply and hot water supply 20. Left-side vertical piping 21. Right-side vertical piping 22.Horizontal piping 23. Tray 24. Condensation water 25.Heat insulation material surface (non-woven fabric) 26.Inorganic architectural board materials 27. Structure for preventing horizontal condensation dripping in inorganic building panels. 28. Structure for preventing vertical condensation dripping in inorganic building panels. 29. Metal duct 30. Structure to prevent condensation water from dripping from ducts 31. Metal corrugated sheet 32. Structure to prevent condensation dripping from metal corrugated sheets

Claims

1. A heat-insulating material for preventing dripping of condensation water, comprising a polyethylene resin foam and a nonwoven fabric disposed on the surface thereof, the base material being a sheet-like polyethylene resin foam having closed cells, the nonwoven fabric being fused or adhered to one surface of the base material, the thickness of the nonwoven fabric as measured based on JIS L1913 being 1.0 mm or less, the average fiber diameter of the fibers constituting the nonwoven fabric being in the range of 10 to 30 μm, the porosity of the fibers of the nonwoven fabric being 85 to 98%, and the filling rate being 2 to 15%, and further, the nonwoven fabric satisfying an effective tensile stress of 25 MPa or less and 1 MPa or more, the effective tensile stress being the apparent stress in the MD direction at a tensile elongation value of 5% in the MD direction divided by the filling rate of 2 to 15%, The heat-insulating material for preventing dripping of condensation water, which is disposed on the outer surface of a pipe, a heat exchanger or a building component, is further characterized in that the water retention capacity calculated per 1 mm of apparent thickness of the nonwoven fabric is 500 g / m 2 or more.

2. An anti-dripping insulation material for condensation water as described in claim 1, characterized in that the ratio of effective tensile stress in the MD direction to the TD direction is 0.14 or more.

3. The heat-insulating material for preventing dripping of condensation water as described in claim 1, characterized in that the fibers constituting the nonwoven fabric of the heat-insulating material are composed of fibers containing at least one of PET resin, polyethylene resin, polypropylene resin, and acrylic resin.

4. 4. The heat insulating material for preventing dripping of condensation water according to claim 3, wherein the fibers constituting the nonwoven fabric of the heat insulating material further contain 30% or less of any of cellulose fibers, pulp and rayon fibers based on the total fiber weight.

5. The heat-insulating material for preventing dripping of condensation water as described in claim 3 or 4, characterized in that at least a portion of the fibers constituting the nonwoven fabric of the heat-insulating material are composed of fibers having a core-sheath structure, or further, the core fibers of the fibers having the core-sheath structure are composed of fibers having a core with a hollow structure, and a sheath portion is formed around the hollow fiber having the core with a hollow structure, and the sheath portion of the core-sheath structure or the sheath portion of the fiber forming the core with the hollow structure is formed of a resin having a lower melting point than the core or the core with the hollow structure.

6. 6. The heat-insulating material for preventing dripping of condensation water according to claim 1, further characterized in that the nonwoven fabric formed on the surface of the resin foam is embossed.

7. 7. A piping comprising a refrigerant pipe, the condensation water drip prevention heat-insulating material according to claim 1, and a nonwoven fabric covering the outer periphery of the piping.

8. A spectacle-shaped piping structure, characterized in that two pipes are integrated by facing each other and heat-sealing or heat-bonding the heat-insulating material for preventing condensation water dripping coated on the outer periphery of the refrigerant pipe described in claim 7.

9. A cylindrical piping structure for refrigerant piping, characterized in that a plurality of refrigerant pipes, drain pipes and wiring are prepared, and the condensation water dripping prevention heat-insulating material described in any one of claims 1 to 6 surrounds the plurality of refrigerant pipes, drain pipes and wiring so that the nonwoven fabric forming surface serves as the outer peripheral surface and the outer peripheral surface shape of the condensation water dripping prevention heat-insulating material has an approximately cylindrical cross-sectional shape, thereby storing the components to be installed inside the piping.

10. A cylindrical piping structure for water supply and hot water supply piping, characterized in that a cross-linked polyethylene pipe and a resin sheath pipe covering the outer periphery of the cross-linked polyethylene pipe are provided as piping for water supply and hot water supply, and the cross-linked polyethylene pipe and the resin sheath pipe covering the outer periphery of the cross-linked polyethylene pipe are surrounded by a condensation water dripping prevention heat-insulating material described in any one of claims 1 to 6, with the nonwoven fabric forming surface serving as the outer periphery and the shape of the outer periphery of the condensation water dripping prevention heat-insulating material having a cross-sectional shape that is approximately cylindrical.

11. 11. The cylindrical piping structure for cold water and hot water supply piping according to claim 10, wherein the resin sheath pipe is covered with a resin foam so as to surround an outer periphery of the sheath pipe.

12. A piping structure in which the condensation water drip prevention heat-insulating material is coated on the outer periphery of a refrigerant pipe, the piping including at least a portion of the piping being vertical piping, the condensation water drip prevention heat-insulating material being coated on the vertical piping so that the nonwoven fabric-forming surface of the condensation water drip prevention heat-insulating material described in any one of claims 1 to 6 forms the outer periphery of the vertical piping.

13. 7. A structure of an air-conditioning duct, wherein the heat-insulating material for preventing dripping of condensation water according to claim 1 is adhered to an outer surface of the air-conditioning duct with the nonwoven fabric surface facing the outer surface.

14. A structure for preventing dripping of condensation water for an inorganic building board, characterized in that the heat-insulating material for preventing dripping of condensation water according to any one of claims 1 to 6 is placed on the surface of an inorganic building board with the nonwoven fabric formed side as the outer surface, or further, the resin foam surface of the heat-insulating material for preventing dripping of condensation water placed on the surface of the inorganic building board with the nonwoven fabric formed side as the outer surface and the opposing surfaces of the surface of the inorganic building board are bonded to each other and arranged in a horizontal plane direction, and the inorganic building board is at least one of a gypsum board and a calcium silicate board.

15. A structure for preventing dripping of condensation water for an inorganic building board, characterized in that a heat-insulating material for preventing dripping of condensation water according to any one of claims 1 to 6 is placed on the surface of an inorganic building board with the nonwoven fabric forming surface as the outer surface, and the inorganic building board is arranged in a vertical plane direction such that the resin foam surface of the heat-insulating material for preventing dripping of condensation water and the opposing surfaces of the surface of the inorganic building board are bonded to each other, and the inorganic building board is at least one of a gypsum board and a calcium silicate board.

16. A structure for preventing dripping of condensation water on a folded plate roof, characterized in that the heat-insulating material for preventing dripping of condensation water according to any one of claims 1 to 6 is adhered to the inner surface of the folded plate roof.

17. A nonwoven fabric having an average fiber diameter of fibers constituting the nonwoven fabric in the range of 10 to 30 μm, a void ratio of the fibers of the nonwoven fabric of 85 to 98%, and a filling rate of 2 to 15%, the thickness of the nonwoven fabric measured based on JIS L1913 is 1.0 mm or less, and an effective tensile stress, which is the value obtained by dividing the apparent stress in the MD direction at a tensile elongation value of 5% in the MD direction in a tensile test by a filling rate of 2 to 15%, satisfies the range of 25 MPa or less and 1 MPa or more, The nonwoven fabric for preventing dripping of condensation water, which is arranged on the outer surface of a pipe, a heat exchanger or a building component, is further characterized in that the water retention capacity of the nonwoven fabric converted into 1 mm of apparent thickness is 500 g / m2 or more.

18. A nonwoven fabric for preventing condensation water from dripping, as described in claim 17, characterized in that the ratio of effective tensile stress in the MD direction to that in the TD direction is 0.14 or more.

19. The nonwoven fabric for preventing dripping of condensation water as described in claim 17, characterized in that the fibers constituting the nonwoven fabric are composed of fibers containing at least one of PET resin, polyethylene resin, polypropylene resin, and acrylic resin, and further characterized in that the fibers are composed of fibers that do not have a core-sheath structure.

20. 20. The nonwoven fabric for preventing dripping of condensation water according to claim 19, characterized in that the fibers constituting the nonwoven fabric further contain 30% or less of any of cellulose fibers, pulp and rayon fibers by total fiber weight.

21. A nonwoven fabric for preventing dripping of condensation water, as described in any one of claims 17 to 20, characterized in that at least a portion of the fibers constituting the nonwoven fabric are composed of fibers having a core-sheath structure, or further, the core fibers of the fibers having a core-sheath structure are composed of fibers having a core with a hollow structure, and a sheath is formed around the fibers forming the core of the hollow structure, forming a hollow multilayer structure fiber, and the sheath of the core-sheath structure or the sheath of the fibers forming the core of the hollow structure is formed from a resin having a lower melting point than the core.

22. The nonwoven fabric for preventing dripping of condensation water according to claim 21, characterized in that at least a part of the fibers constituting the nonwoven fabric is formed from short fibers, or from long fibers crossing the weft and warp directions or oblique long fibers.

23. A nonwoven fabric for preventing dripping of condensation water, characterized in that the short fiber nonwoven fabric described in claim 22 is produced by a chemical bond method, a thermal bond method, a spunlace method, an airlaid method, or a needle punch method.

24. A method for constructing a piping structure in which the condensation-water-dripping prevention heat-insulating material according to any one of claims 1 to 6 is wrapped around the outer circumference of a refrigerant pipe, and when the pipe is vertical or oblique, the method for forming a piping structure in which the condensation-water-dripping prevention heat-insulating material is arranged in a direction in which the effective tensile stress of the condensation-water-dripping prevention heat-insulating material satisfies the range of 25 MPa or less and 1 MPa or more, in a horizontal direction perpendicular to the direction of the vertical pipe.

25. A method for forming a drip-prevention structure for condensation water in an air-conditioning duct, wherein the sides of the air-conditioning duct are arranged opposite each other in at least a vertical direction so as to sandwich the upper and lower surfaces of the duct, and the nonwoven fabric of the drip-prevention insulation material for condensation water dripping as described in any one of claims 1 to 6 is arranged on the sides in a horizontal direction perpendicular to the vertical duct side surfaces such that the effective tensile stress of the nonwoven fabric satisfies the range of 25 MPa or less and 1 MPa or more.

26. In a method for forming a structure for preventing dripping of condensation water in an inorganic building material for architecture, when the condensation structure of the inorganic building material for architecture is a vertical wall structure, the nonwoven fabric of the heat-insulating material for preventing dripping of condensation water described in any one of claims 1 to 6 is arranged as an outer surface on the surface of the vertical wall of the inorganic building material for architecture, with the effective tensile stress of the nonwoven fabric of the heat-insulating material for preventing dripping of condensation water as described in any one of claims 1 to 6 being oriented in a horizontal direction perpendicular to the direction of the vertical wall structure, the effective tensile stress being 25 MPa or less and 1 MPa or more.

27. A method for forming a structure for preventing dripping of condensation water from a folded plate roof, comprising: arranging the nonwoven fabric of the heat-insulating material for preventing dripping of condensation water as described in any one of claims 1 to 6 as an outer surface on the back surface of the folded plate roof, in a direction perpendicular to the folding direction of the folded plates of the folded plate roof, such that the effective tensile stress of the nonwoven fabric of the heat-insulating material for preventing dripping of condensation water from the folded plate roof satisfies the range of 25 MPa or less and 1 MPa or more.

Images