Net-like materials and net-like heating elements

Abstract

The objective is to obtain a net-like material and a net-like heating element that exhibit good elastic deformation in the elongation direction and have minimal change in electrical resistance when elastically deformed in the elongation direction. [Solution] The net-like material has a mesh structure composed of conductive linear bodies 21a, 21b, 21c, 21d, 21e, and 21f. Each mesh 12 of the mesh structure is formed in a polygonal shape by multiple linear bodies 21a, 21b, 21c, 21d, 21e, and 21, and has intersections 25a, 25b, 25c, 25d, 25e, and 25f between different linear bodies. Different linear bodies 21a and 21b are connected at the intersection 25b so that there is no displacement between them in the longitudinal direction. The intersection 25b allows the angle of intersection between different linear bodies 21a and 21b to change due to elastic deformation.

Description

[Technical Field]

[0001] This invention relates to a net-like material and a net-like heating element. [Background technology]

[0002] For example, car seat heaters are installed under the seat cover, so they need to be thin and have few bumps or uneven surfaces. Also, when a car occupant leans back in the seat, the seat elastically deforms in the stretching direction, so the seat heater also needs to be able to elastically deform in the stretching direction accordingly.

[0003] Patent Document 1 describes a fabric-like heater that can undergo elastic deformation in the stretching direction. This fabric-like heater is formed by creating multiple loops with conductive threads and weaving the loops together to form a single piece. This gives the fabric elasticity, allowing it to stretch freely in all directions. In other words, the elasticity of the fabric is achieved by changing the way the loops intertwine.

[0004] The cloth heater described in Patent Document 2 has a similar configuration. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. WO2013 / 085051 [Patent Document 2] Patent No. 6842162 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, if the entanglement of loops is altered to give the fabric elasticity, the electrical resistance of the fabric changes, as detailed in Patent Document 2.

[0007] When such a fabric is used as a heater for the aforementioned automobile seats, there is a problem in that its electrical resistance changes when the fabric undergoes elastic deformation in the stretching direction, which in turn alters the heating characteristics of the heater.

[0008] Therefore, the present invention aims to solve these problems and provide a net-like material and a net-like heating element in which different linear bodies are connected to each other at their intersections so that there is no displacement in the longitudinal direction of the linear bodies, which allows for good elastic deformation in the elongation direction and minimizes the change in electrical resistance when elastically deformed in the elongation direction. [Means for solving the problem]

[0009] To achieve this objective, the net-like material of the present invention is A net-like material having a mesh structure composed of conductive linear bodies, Each mesh in the aforementioned mesh structure is formed in a polygonal shape by multiple linear bodies and has intersections between different linear bodies. The different linear bodies are connected at the intersection such that no displacement occurs between them in the longitudinal direction of the linear bodies. The aforementioned intersection is characterized in that the intersection angle between the different linear bodies can be changed by elastic deformation.

[0010] In this configuration, the intersection angle between different linear elements can be changed by the elastic deformation of the intersection points between them. As the intersection angle between different linear elements changes due to this elastic deformation, the distance between pairs of intersection points that are not adjacent to each other in the polygonal shape can be geometrically increased. Therefore, the net-like material of the present invention can stretch well due to the elastic deformation of the intersection points between linear elements. Furthermore, by geometrically increasing the distance between pairs of intersection points that are not adjacent to each other in the polygonal shape, the net-like material undergoes elastic deformation, and the linear elements themselves do not need to stretch at that time, thus preventing changes in electrical resistance due to stretching of the linear elements. In addition, the intersection points between linear elements are connected, so when the net-like material undergoes elastic deformation, the intersection points do not shift in the longitudinal direction of the linear elements, thus preventing changes in electrical resistance due to changes in the shape of the intersection points. For this reason, a net-like material can be made in which the change in electrical resistance when elastically deformed in the stretching direction is small.

[0011] Preferably, the net-like material of the present invention is composed of linear bodies made of fibrous material, and the net-like material is made of the fibrous material woven into a net-like structure. In this case, it is preferable that the fibrous material is heat-bondable fiber.

[0012] According to the net-like material of the present invention, the conductive fibrous material is preferably one in which the surface of the core material is coated with a metal film.

[0013] According to the net-like material of the present invention, The polygonal mesh has multiple intersections between different linear bodies. Preferably, the mesh is such that when the intersection angle between different linear bodies changes at the intersection, the distance between separate intersections that are not adjacent to each other in the polygonal shape changes.

[0014] According to the net-like object of the present invention, when the crossing angle between different linear bodies changes at the crossing part, the amount of change in the distance between the first crossing part and the second crossing part that are not adjacent to each other in the polygonal shape is preferably larger than the amount of change in the distance between the third crossing part that is adjacent to the first crossing part and the first crossing part in the polygonal shape.

[0015] According to the net-like object of the present invention, there are a plurality of combinations of crossing parts that are not adjacent to each other in the polygonal shape, when a tensile stress acts in the plane direction of the net-like object, it is preferable that the elongation of the net-like object along the direction in which at least one combination of crossing parts that are not adjacent to each other in the polygonal shape are aligned is 3% or more.

[0016] According to the net-like object of the present invention, it is preferable that the metal film is composed of at least one of a copper film, a nickel film, a tin film, a silver film, and an aluminum film.

[0017] According to the net-like object of the present invention, it is preferable that the volume resistivity is 5.0 to 120.0 Ω.

[0018] According to the net-like object of the present invention, it is preferable that the volume resistivity when the elongation of the net-like object along the direction in which crossing parts that are not adjacent to each other in the polygonal shape are aligned is 3% is 3.5 to 150.0 Ω.

[0019] The net-like heating element of the present invention is composed of the above-mentioned net-like object.

[0020] According to the net-like heating element of the present invention, it is preferable to have a pair of electrodes arranged at a distance in the plane direction of the net-like object.

Effects of the Invention

[0021] According to the present invention, it is possible to obtain a net-like object and a net-like heating element that elastically deform well in the elongation direction and have little change in electrical resistance when elastically deformed in the elongation direction. [Brief explanation of the drawing]

[0022] [Figure 1] This figure shows the main part of the net-like material according to the first embodiment of the present invention. [Figure 2] This figure shows a magnified view of a portion of Figure 1. [Figure 3] This is a cross-sectional view along the line III-III in Figure 2. [Figure 4] This figure shows the main part of the net-like material according to the second embodiment of the present invention. [Figure 5] This figure shows a magnified view of a portion of Figure 4. [Figure 6] This figure shows the deformation in the planar direction of the portion shown in Figure 5. [Figure 7] Figure 6 is a diagram illustrating the deformation in the planar direction. [Figure 8] This figure shows a net-like heating element according to an embodiment of the present invention. [Figure 9] This figure shows a partial fracture of the net-like material in Figure 1. [Figure 10] This figure shows how another part of the net-like structure in Figure 1 has broken. [Modes for carrying out the invention]

[0023] [Net-like material of the first embodiment] The net-like material of the first embodiment of the present invention shown in Figures 1 to 3 has a mesh structure formed in a polygonal shape by linear bodies 11, as schematically shown in Figure 1. In other words, a linear body is a member that forms one side of the polygonal mesh. In the net-like material shown in detail in an enlarged view in Figure 2, each mesh 12 is formed in a roughly rhombic shape by multiple linear bodies, i.e., four linear bodies 11a, 11b, 11c, and 11d. The illustrated mesh structure is formed by multiple long linear bodies 13 arranged in an upward-sloping direction to the right in Figure 1, and multiple long linear bodies 14 arranged in an upward-sloping direction to the left in Figure 1. Adjacent long linear bodies 13, 13 arranged in an upward-sloping direction to the right are spaced apart from each other and are roughly parallel, and similarly, adjacent long linear bodies 14, 14 arranged in an upward-sloping direction to the left are spaced apart from each other and are roughly parallel. As a result, intersections 15 (15a, 15b, 15c, 15d) are formed between the linear bodies 11a and 11c in the direction of the long linear body 13 which is arranged upward to the right, and the linear bodies 11b and 11d in the direction of the long linear body 14 which is arranged upward to the left.

[0024] As shown in Figure 2, at intersection 15b, the linear body 11a in the direction of the long linear body 13 shown in Figure 1 and the linear body 11d in the direction of the long linear body 14 shown in Figure 1 intersect with a predetermined intersection angle θ1. The same configuration is observed at the other intersections 15a, 15c, and 15d.

[0025] The linear bodies 11, 13, and 14 are electrically conductive. The configuration for achieving this conductivity is arbitrary. In the illustrated example, as shown in Figure 3, the surface, or periphery, of the core material 16 is covered with a metal film 17. The core material 16 is not limited, but it is preferably made of synthetic resin, and in particular, it is preferably a fibrous material made of synthetic resin, as in the second embodiment which will be described in detail later.

[0026] At the intersection 15, for example, at the intersection 15a shown in Figure 2, the linear body 11a and the linear body 11b are connected so as to be an integral part. In the present invention, "connected so as to be an integral part" means, for example, that at the intersection 15a, the linear body 11a and the linear body 11b are fixed so as not to shift in their longitudinal direction. For example, when resin is used as the core material 16 as described above, at the intersection 15a, the resin constituting the core material 16 of the linear body 11a and the resin constituting the core material 16 of the linear body 11b are integrally formed by extrusion molding or the like, or when a fibrous material is used as the core material 16 as in the second embodiment which will be described in detail later, the linear bodies 11, 13, and 14 are fixed at the intersection 15 so as not to shift in their longitudinal direction by heat bonding using heat-bonding fibers, or by bonding with an adhesive, or by laminating with a film.

[0027] In a mesh made simply from ordinary woven or knitted fabrics, the intersections are not fixed and are therefore mobile, making it easy for the constituent threads to shift in the longitudinal direction at the intersections that form the mesh. In contrast, when forming a net-like material of the present invention with woven or knitted fabrics, as in the second embodiment described later, the mesh can be constructed using, for example, heat-bondable fibers and heat-bonded, so that, for example, the linear body 11a and the linear body 11b at the intersection 15a do not shift in the longitudinal direction.

[0028] Figure 2 shows an example of the first embodiment in which, for example, at the intersection 15a, the resin constituting the core material 16 of the linear body 11a and the resin constituting the core material 16 of the linear body 11b are integrally formed. The net-like material shown in Figure 1 has a similar configuration. The mesh structure may be formed by extruding resin wire members as described above, as in the first embodiment, or it may be formed from woven or knitted fabrics, as in the second embodiment which will be described in detail later, or it may be a different configuration. In any case, for example, the mesh structure is obtained by integrating the linear body 11a and the linear body 11b at the intersection 15a. The same applies to other intersections. Such a mesh structure can be formed, for example, in the case of woven fabrics by adjusting the mesh size of the warp and weft threads. In the case of knitted fabrics, it can be formed by creating a mesh structure knitted fabric using a tricot knitting machine, a raschel knitting machine, a circular knitting machine, etc. Furthermore, a method of forming a wire member made of resin by extrusion molding is described in detail, for example, in Japanese Patent Publication No. 34-4185.

[0029] In the mesh structure shown in Figures 1 and 2, although detailed illustrations are omitted, at the intersection 15, the core material 16 of the linear bodies 11 and 13 and the resin constituting the core material 16 of the linear bodies 11 and 14 are integrated with each other, and the portion where the resins are integrated is covered with a metal film, similar to that shown in Figure 3.

[0030] In the mesh structure in which linear bodies 11, 13 and linear bodies 11, 14 are integrated at the intersection 15 as described above, the geometric shape of the mesh can be changed if the resin constituting the core material 16 of the linear bodies 11, 13, and 14 at the intersection 15 is elastically deformable. In particular, in the present invention, when stress is applied in the planar direction of the mesh structure, if the degree of elastic deformation of the resin core material 16 at the intersection 15 is greater than the degree to which the core material 16 of each linear body 11, 13, and 14 stretches in the longitudinal direction, the shape of the polygon can be changed by changing the position of the vertices of the polygon without substantially increasing the length of the sides of the polygon.

[0031] In other words, in the net-like material of the present invention, as described above, it is necessary that displacement in the longitudinal direction of the constituent threads is less likely to occur at the intersections for forming the mesh. However, this alone is not enough. As described above, the resin constituting the core material 16 of the linear bodies 13 and 14 at the intersection 15 must be elastically deformable to the extent that it can change the geometric shape of the mesh. For example, it is possible to prevent the above-mentioned displacement by forming the intersections rigidly, but if the intersections are formed rigidly to the extent that the above-mentioned elastic deformation cannot be performed, the problem of the present invention, which is to obtain a net-like material and a net-like heating element that can be elastically deformed well in the elongation direction and have little change in electrical resistance when elastically deformed in the elongation direction, cannot be solved.

[0032] The technical features described above will be explained in detail with reference to Figure 2. In the illustrated example, the shape of one mesh 12 is rhombic, and it has four intersections 15a, 15b, 15c, and 15d that form the vertices of the rhombus, and four linear bodies 11a, 11b, 11c, and 11d that form the sides of the rhombus.

[0033] In this configuration, when a tensile stress SW along the transverse direction of the paper in Figure 2 acts on the mesh 12, the intersections 15a, 15b, 15c, and 15d undergo elastic deformation. As shown by the dashed lines, the intersection angle θ1 at intersections 15b and 15d becomes a smaller intersection angle θ2. This causes the distance between pairs of intersections 15b and 15d that are not adjacent to each other but face each other along the transverse direction of the paper to become longer than when the tensile stress SW is not acting, as shown by the solid lines.

[0034] In this case, the length of each linear body 11 stretched between the intersections 15b and 15d does not substantially change, and no displacement occurs in the length direction of the linear body 11 at the intersections 15a, 15b, 15c, and 15d. Therefore, although the surface of the core material 16 of each linear body 11 is covered with a metal film 17, the electrical resistance between the intersections 15b and 15d does not substantially change. In other words, in the mesh structure shown in the figure, when a tensile stress SW along the transverse direction of the plane of paper in Figure 2 acts on the mesh 12, elongation occurs in the mesh 12 along the transverse direction of the plane of paper in Figure 2, but its electrical resistance can be kept substantially unchanged.

[0035] Furthermore, since the length of each linear body 11 stretched between the intersections 15b and 15d does not substantially change, as the distance between the pair of intersections 15b and 15d increases, the distance between the other pair of intersections 15a and 15c decreases, as shown by the dashed lines in Figure 2.

[0036] This phenomenon occurs similarly when tensile stress along the vertical direction of the plane of Figure 2 acts on the mesh 12. Moreover, regardless of the direction in which tensile stress acts within the plane of Figure 2, the distance between pairs of intersections 15b and 15d and the distance between other pairs of intersections 15a and 15c change in both the vertical and horizontal directions, and in that case, the electrical resistance between intersections 15b and 15d and the electrical resistance between other intersections 15a and 15d do not change substantially.

[0037] Therefore, when the net-like material of the present invention is used as a net-like heating element that utilizes Joule heating, and this net-like heating element is installed under the seat cover as a heater for a car seat, the seat deforms when a person sits on it, causing the net-like heating element to undergo elastic tensile deformation. However, the electrical resistance of the net-like heating element does not change at that time, and therefore the heating characteristics do not change, which is an advantage.

[0038] To achieve these characteristics, when forming a net-like material by extrusion molding, the resin for the core material 16 shown in Figure 3 can be polyester such as polyethylene terephthalate, polyolefins such as polyethylene and polypropylene, or polyamides such as nylon. Among these, polyethylene terephthalate is preferably used when constructing a net-like heating element due to its heat resistance and appropriate elongation. The core material 16 is preferably in the form of a monofilament because it is less likely to elongate when the above-mentioned tensile stress is applied and the intersection angle θ1 is easily changed.

[0039] When forming a net-like material by weaving or knitting, it is preferable that the core material 16 be in the form of fibers, as in the second embodiment described in detail below, and in that case, it is preferable that the linear body is a fibrous core material 16 with a metal film coated on its surface.

[0040] [Net-like material of the second embodiment] The net-like material of the second embodiment of the present invention shown in Figures 4 to 7 is composed of linear bodies made of fibrous material, and the net-like material of this second embodiment is composed of the aforementioned fibrous material woven into a net-like structure.

[0041] The linear body has a core material 16 similar to that shown in Figure 3, as in the first embodiment, and this core material 16 is composed of a fibrous material. This fibrous material may be in the form of a monofilament, a multifilament in the form of multiple single fibers joined together to form a single thread, or a spun yarn made of short fibers. The fibrous material may further include multiple monofilaments or multifilaments, for example, a form in which multiple filaments are held together, or a form in which twisted yarn is formed. Also, as shown in Figure 5, when the net-like material is formed, for example, as a mesh knitted fabric, the fibrous material of the linear body 11 present at each intersection is formed by multiple multifilaments.

[0042] When forming a net-like material by weaving or knitting, the fibrous material can be synthetic fibers made from synthetic resins, as well as regenerated fibers, natural fibers such as cotton and wool, or combinations thereof. Among these, synthetic fibers are preferable from the viewpoint of heat generation and heat resistance. As resins constituting the synthetic fibers, the same resins as in the case of extrusion molding described above can be mentioned, as well as acrylic resins and aramid resins. Among these, polyethylene terephthalate is preferably used because it has appropriate elongation and excellent heat resistance, resulting in good process stability during the plating process for forming the metal film 17 shown in Figure 3.

[0043] In the examples shown in Figures 4 to 7, the net-like structure has a hexagonal mesh 12, as depicted in the figures. This hexagonal mesh 12 has six linear bodies 21a, 21b, 21c, 21d, 21e, and 21f, and six intersections 25a, 25b, 25c, 25d, 25e, and 25f. The manner of elastic deformation of these intersections 25a, 25b, 25c, 25d, 25e, and 25f, and the linear bodies 21a, 21b, 21c, 21d, 21e, and 21f when tensile stress is applied in the planar direction of the net-like structure is the same as in the first embodiment described above.

[0044] By using heat-bondable fibers as the fibrous material, intersections are formed at intersections 25a, 25b, 25c, 25d, 25e, and 25f where three linear bodies are heat-bonded together. For example, at intersection 25a, three linear bodies 21a, 21f, and 21g are heat-bonded together.

[0045] In this case, the linear bodies 21a, 21b, 21c, 21d, 21e, 21f, and 21g are concepts that include other linear bodies of the network, as shown in detail in Figure 5. Specifically, a net-like material can be obtained by forming a network structure using heat-bonded fibers in a woven or knitted fabric, and then heat-bonding it by heat treatment at a temperature above the melting point of the heat-bonded fibers.

[0046] The content of heat-adhesive fibers in the linear bodies 21a, 21b, 21c, 21d, 21e, 21f, 21g and the intersections 25a, 25b, 25c, 25d, 25e, 25f is not limited as long as the aforementioned connections are made. The linear bodies can also be made by combining heat-adhesive fibers and non-heat-adhesive fibers with different melting points. The heat-adhesive components constituting the heat-adhesive fibers are preferably those with a melting point (or softening point if there is no melting point; the same applies hereinafter) of 80 to 170°C, and more preferably those with a melting point of 80 to 140°C. Specific examples of heat-adhesive components include polyolefin resins such as polyethylene and polypropylene, polyester resins such as copolymerized polyethylene terephthalate obtained by copolymerizing copolymer components such as isophthalic acid, and nylon resins.

[0047] In this specification, the melting point refers to the temperature that gives the extreme value of the melting absorption curve measured using a differential scanning calorimeter (DSC7, manufactured by PerkinElmer) at a heating rate of 20°C / min. Examples of heat-bonding fibers include a fully melting type composed of only a single heat-bonding component. Alternatively, a core-sheath type heat-bonding fiber is provided, in which a heat-bonding component is arranged in the sheath portion, and a synthetic resin component with a melting point preferably 20°C or more, more preferably 30°C or more, higher than the melting point of the sheath portion is arranged in the core portion. In the case of a core-sheath type heat-bonding fiber, the core component is not particularly limited, but for example, a synthetic resin component with a melting point of 150 to 300°C, more preferably 200 to 300°C, and with a melting point 20°C or more higher than the melting point of the sheath portion is provided. A specific example of such a synthetic resin component is polyethylene terephthalate.

[0048] In the mesh structure shown in Figures 4 to 7, the hexagonal mesh 12 is formed in a vertically elongated shape along the vertical direction of the paper in the figures. Furthermore, the intersections 25a, 25b, 25c, 25d, 25e, and 25f are configured such that the length along the vertical direction of the paper in Figures 4 to 7 is greater than the length along the horizontal direction. Therefore, as shown in Figures 6 and 7, when a tensile stress SW is applied in the vertical direction along the vertical direction of the paper in these figures, the distance between opposing intersections that are not adjacent to each other tends to be longer than when a tensile stress is applied in the horizontal direction along the left-right direction of the paper.

[0049] In addition, by making the vertical and horizontal lengths of the intersections 25a, 25b, 25c, 25d, 25e, and 25f equal, that is, by creating a roughly hexagonal mesh 12, similar properties can be obtained when tensile stress is applied horizontally and when tensile stress is applied vertically. Furthermore, by devising the shapes of the intersections 25a, 25b, 25c, 25d, 25e, and 25f, it is possible to achieve uniform properties regardless of the direction in which tensile stress is applied within the plane of the illustrated net-like material.

[0050] In the net-like material of the second embodiment, as in the net-like material of the first embodiment, when a tensile stress SW along the vertical direction of the plane of the paper acts on the mesh 12, elongation occurs in the mesh 12 in the vertical direction of the plane of the paper, but its electrical resistance can be made to not change substantially.

[0051] [Technical matters common to the first and second embodiments] Examples of metal films 17 shown in Figure 3 include copper films, nickel films, tin films, silver films, aluminum films, gold films, iron films, chromium films, and tin films. These films may be single-layer films, laminated films of multiple types of metal films, or films made of alloys of multiple metals. In particular, it is preferable that the film consists of at least one of copper films, nickel films, tin films, silver films, and aluminum films. Furthermore, when laminated films of multiple types of metal films, the outermost layer is preferably a nickel film or a tin film from the viewpoint of corrosion resistance. Methods for forming such metal films 17 include, for example, immersing a net-like structure formed only from the core material 16 shown in Figure 3 in a metal-containing solution, i.e., a plating solution, or electroplating this net-like structure. With these methods, plating can be applied to almost 100% of the surface of the net-like structure. Alternatively, when the net-like structure is constructed from woven or knitted fabric as in the second embodiment, in addition to impregnating the woven or knitted fabric in a plating solution or electroplating as described above, the net-like structure can also be formed using pre-plated yarn.

[0052] The linear bodies 11, 13, 14, and 21a-21f shown in the figure only need to be broadly conductive, and as mentioned above, their configuration is arbitrary. For example, a configuration in which the core material 16 is covered with a metal film 17, as described above, or other configurations without a metal film 17 can be used. For example, a configuration in which a conductive substance is kneaded into the resin used to form the core material 16 can be mentioned.

[0053] The mesh 12 is formed in a polygonal shape and is not limited to rhombuses as shown in Figures 1 and 2, but can be any even-numbered or odd-numbered polygon as long as the above-mentioned performance is achieved. For example, it may be a hexagon as shown in Figures 4 to 7, or it may be a square, pentagon, octagon, or any other polygon, or even a polygon that is very close to a circle.

[0054] The size of the mesh 12 is not particularly limited and can be changed as appropriate so that the net-like material has the desired electrical resistance and heat generation characteristics. The size of the mesh 12 is 0.005 to 2.0 cm. 2 Preferably, 0.01 to 1.0 cm 2 It is even more preferable that this be the case.

[0055] As described above, the net-like material only needs to have a degree of elastic deformation of the resin at the intersections 15, 25a-25f when stress is applied in the planar direction of the mesh structure, which should be greater than the degree to which each linear body 11, 13, 14, 21a-21f stretches in the longitudinal direction. Furthermore, because the intersections are connected, there is no displacement of the linear bodies in the longitudinal direction at the intersections, so the shape of polygons such as the rhombuses described above can be changed by changing the position of the vertices without substantially increasing the length of the sides of the polygons of the mesh 12. With this configuration, the net-like material can increase or decrease the distance between separate intersections 15 that are not adjacent to each other in the polygon shape when the intersection angle θ1 of linear bodies 11a and 11d changes at the intersection 15 shown in Figure 2. As a result, when a tensile stress SW is applied in the planar direction of the net-like material, if there are multiple combinations of intersections 15 that are not adjacent to each other in the polygonal shape, the elongation of the net-like material along the direction in which at least one combination of intersections 15 that are not adjacent to each other in the polygonal shape are aligned can be 3% or more. Preferably, the elongation of the net-like material is 5% or more, and more preferably 15% or more depending on the application. Furthermore, it is preferable that the upper limit of the elongation rate is 50% or less.

[0056] As shown in the figure, when the mesh 12 formed by extrusion molding, weaving, or knitting is rhombic, the separate intersections that are not adjacent to each other in the polygonal shape refer to intersection 15b and intersection 15d, as exemplified in Figure 2, or intersection 15a and intersection 15c. This allows us to understand that there are multiple combinations of pairs of intersections.

[0057] When a net-like material is made of woven fabric, the desired elongation characteristics can be easily achieved when tensile stress is applied in the bias direction, i.e., in the direction of a line at a 45-degree angle to the selvage (both ends) of the fabric. Therefore, when a net-like material is made of woven fabric, the elongation of the net-like material when tensile stress is applied in the bias direction in the surface direction of the net-like material can be made to be 3% or more.

[0058] When using a mesh-like material as a mesh-like heating element, which will be described in detail later, it is necessary to set the volume resistivity of the mesh-like material within an appropriate range so that the degree of heat generation is moderate. To achieve this, the type of metal used to form the metal film 17 can be changed, the thickness of the metal film 17 can be adjusted, the mesh size can be adjusted, or a semiconductor can be used as a material to exhibit conductivity. From this viewpoint, the volume resistivity of the mesh-like material is preferably 5.0 to 120.0 Ω, more preferably 10.0 to 100 Ω, and even more preferably 20 to 80 Ω. In particular, the combination of the mesh size and the type of metal of the metal film greatly affects the heat generation characteristics.

[0059] Furthermore, when using a net-like material as a net-like heating element, it is preferable that the temperature generated is, for example, 30 to 110°C when 12V is applied for 5 minutes.

[0060] To reiterate, as described above, when stress is applied in the planar direction of the mesh structure, the degree of elastic deformation of the resin at the intersections 15, 25a-25f is greater than the degree to which each linear body 11, 13, 14, 21a-21f stretches in the longitudinal direction. This allows the position of the vertices to be changed without substantially increasing the length of the sides of the polygons of the mesh 12. As a result, the mesh has the characteristic that its volume resistivity does not change substantially even when it is greatly deformed in the elongation direction.

[0061] Therefore, the net-like material has a concentration of 5.5 g / cm² in the plane direction of the net-like material. 2The volume resistivity under the applied load can be set to 3.5 to 150.0 Ω.

[0062] Furthermore, the net-like material can be configured such that its volume resistivity is 3.5 to 150.0 Ω when the elongation of the net-like material along the direction in which separate intersections that are not adjacent to each other in the polygonal shape are aligned is 3%. Preferably, the volume resistivity when the elongation of the net-like material is 3% is 7.0 to 100 Ω, and more preferably 20 to 80 Ω.

[0063] These characteristics are extremely useful when a net-like material is installed under a seat cover as a heater for a car seat, as a net-like heating element. This is because when a person sits on a car seat, the seat deforms due to their weight, causing tensile elongation in the heater. However, even in this case, the electrical resistance of the heater does not change substantially, thus preventing any change in the heating characteristics of the heater. Furthermore, since the net-like heating element is made of a net-like material having a mesh structure composed of linear bodies 11, 13, 14, and 21a to 21f, it is made of a material that is thin and has few uneven surfaces or steps, making it particularly suitable as a heater for a car seat.

[0064] The basis weight of a net-like material is not limited to a specific type, as it varies greatly depending on the materials and metal films that make up the linear structure. However, from the standpoint of ease of handling and transport, lighter weight is preferable, for example, 30-250 g / m². 2 Preferably, 40-200 g / m 2 This is more preferable. If the basis weight is within the above range, the net-like heating element can have good elastic deformability and heat generation properties, and can also be made easy to handle.

[0065] [Embodiment of a Net-like Heating Element] Figure 8 shows an embodiment of a net-like heating element. Here, the net-like material 30 is the same as that of the first embodiment. As shown in the figure, a pair of electrodes 31 and 32 are provided at a distance from each other in the planar direction of the net-like material 30, which is formed from linear bodies 11, 13, and 14 having the intersection 15 shown in Figure 1. Each electrode 31 and 32 is electrically connected to the net-like material 30 at its respective position. In the illustrated example, the electrodes 31 and 32 are formed in a strip shape from a conductor and are arranged parallel to each other. These pairs of electrodes 31 and 32 are connected to a power supply 33.

[0066] When power is supplied to the net-like material 30 between electrodes 31 and 32, heat is generated by Joule heating, and the net-like material 30 functions as a net-like heating element. As described above, even if the net-like material 30 undergoes elastic deformation in the tensile direction, the electrical resistance between electrodes 31 and 32 does not change substantially, and therefore the heating characteristics do not change substantially either.

[0067] The electrodes 31 and 32 can be formed in any manner. In particular, electrodes 31 and 32 that can similarly deform elastically in accordance with the net-like material 30 which undergoes tensile elastic deformation are preferred. Examples of such materials include woven fabrics, knitted fabrics, or net-like materials that are neither woven nor knitted, composed of conductive linear bodies. Examples of conductive linear bodies include tinned copper wire, copper wire, and nickel wire. Examples of knitted fabrics include flat-braided copper wire. Examples of net-like materials include wire mesh. Furthermore, as an example of a material that can similarly deform elastically in accordance with the net-like material 30 which undergoes tensile elastic deformation, the above-mentioned strip-like material, especially a thin strip-like material formed in the shape of a tape, can be mentioned. For example, a tape-shaped wire mesh can be given as one example. The electrodes 31 and 32 can be attached to the net-like material 30 by sewing or crimping.

[0068] In a mesh-type heating element, it is difficult to avoid the rupture of a very small number of the numerous meshes 12 that make up the mesh for some reason. In such cases, the following measures can be taken to minimize the reduction in heating characteristics.

[0069] Figure 9 shows what happens when the intersection 15 in the mesh 12 shown in Figure 2 and other figures breaks. In Figure 9, the thin arrows represent current. In this case, when the mesh 12 is diamond-shaped as shown, all four linear bodies 11a, 11b, 11c, and 11d that were connected to the intersection 15 before the break become uncurrent-conducting. As a result, a relatively wide area 36 stops generating heat, as shown in the figure.

[0070] In contrast, Figure 10 shows what happens when one linear element 11a in the mesh breaks. In Figure 10, the thin arrows similarly represent the current. In this case, only one linear element 11a in the diamond-shaped mesh 12 is no longer energized. As a result, as shown in the figure, the area 37 that stops generating heat is limited to a narrower range than in the case of Figure 9.

[0071] When forming a net-like heating element, if excessive tensile stress or other factors inevitably cause the mesh 12 to break as described above, the deterioration of the heating characteristics can be minimized by setting the material strength so that the linear body 11 is more likely to break than the intersection 15.

[0072] The applications of net-like materials as net-like heating elements are not particularly limited. In addition to the heaters for automobile seats mentioned above, other examples include food warming devices, clothing with heat retention properties, hand warmers, electric blankets, electric sheets, cooking utensils, nets for greenhouse cultivation, snow melting nets, and protective nets. [Examples]

[0073] Next, the present invention will be specifically described with reference to examples. The various characteristic values ​​and evaluations in the examples are as follows.

[0074] (1) Elongation of the net-like heating element According to JIS L1096 Elongation Method B (Load 14.7N), the elongation of the net-like heating element was measured in the direction perpendicular to the longitudinal direction of the two electrodes.

[0075] (2) Volume resistivity of the net-like heating element when it is not extended. A digital multimeter (Ohm Electric Co., Ltd., model number: TDB-401) was connected via clips to the portion of the two electrodes of the net-like heating element that protruded from the sample along the length of the electrodes, and the volume resistance between the electrodes was measured.

[0076] (3) Volume resistivity of the net-like heating element when extended The net-like heating element was fixed in an extended state so that its elongation length was 3% in any direction, and the volume resistivity between the electrodes was measured in the same manner as in (2) above.

[0077] (4) Mesh size A mesh-like heating element was photographed from directly above using a Dino-Lite DIGITAL MICROSCOPE Premier AD4113T (manufactured by ANMO Electronics Corporation). The mesh size (gaps) was determined from the obtained images using DinoCapture 2.0 software. The average value obtained with a sample size of n=10 was defined as the mesh size.

[0078] (5) Eyes The basis weight of the net-type heating element was measured according to JIS L 1096 (2010), "8.3.2 Mass per unit area under standard conditions, Method A".

[0079] (6) Heat generation characteristics of the net-like heating element when it is not extended Similar to (2) above, a digital multimeter was connected to the electrode portion of the net-like heating element sample via clips, and a voltage of 12V was applied. The heating properties after 5 minutes were observed using a thermograph (Ichinen TASCO, FLIR C3-X). The maximum heating temperature (°C) in the heating portion of a 6cm x 12cm sample was measured. Five samples were prepared, and the maximum heating temperature of each sample was measured. The average of the maximum heating temperatures of the three samples (excluding the samples with the highest and lowest temperatures) was used to evaluate the heating characteristics.

[0080] (Example 1) As the core material, a combination of heat-bonded fibers (Unitika Trading Co., Ltd.'s "Melset," with a melting point of 180°C for the heat-bonding component and 84dtex24 filaments) and regular polyester fibers (with a melting point of 265°C and 84dtex36 filaments) was used. Using this core material, a tricot mesh fabric with a knitting density of 40 courses / 28 wales and a hexagonal stitch pattern was produced.

[0081] Next, the intersecting parts were connected (fixed) by applying a dry heat treatment at 180°C for 1 minute to heat-bond the heat-bonded fibers together.

[0082] Furthermore, the entire surface of the knitted fabric was nickel-plated using an electrolytic plating method to obtain a net-like material. The resulting net-like material had the form shown in Figure 5, and consisted of linear bodies in which substantially the entire surface of the core material was coated with a nickel film. The size of one mesh was 16.8 mm. 2 The basis weight is 74g / m². 2 That was the case.

[0083] Next, with the wale direction as the vertical direction and the course direction as the horizontal direction of the obtained net-like material, a sample measuring 6 cm vertically and 13 cm horizontally was cut from the net-like material. In addition, two tape-shaped conductors (7 cm long, 2 cm wide) made of conductive tape (manufactured by ESCO, model number: EA944AA-4) made of tinned copper soft wire in a knitted bag shape were prepared as electrodes. Next, the two electrodes were placed on the net-like material sample so that the vertical direction of the sample and the length direction of the electrodes were parallel, with a 12 cm gap between them at a point 0.5 cm from the ends in the width direction of the electrodes. The electrodes were then fixed to the sample by sewing with polyester thread using a sewing machine to obtain a net-like heating element. Each electrode was positioned so that it extended 0.5 cm in the length direction and 1.5 cm in the width direction from the sample.

[0084] (Comparative Example 1) As the linear body having conductivity, a metal foil co-twisted yarn obtained by winding a tinned soft copper wire foil around a polyester false-twisted yarn (167 dtex 36 filaments) was used, and using a Koike tubular knitting machine (3 inches, 190 needles), a net-like knitted fabric of a single jersey stitch was obtained with a knitting density of 29 courses / 25 wales.

[0085] In the obtained knitted fabric, different linear bodies were not connected at the intersection. Also, the size of one mesh was 0.33 mm 2 and the areal density was 256 g / m 2 Then, with the wale direction of the obtained net-like knitted fabric of a single jersey stitch as the vertical direction and the course direction as the horizontal direction, a sample of 13 cm in length and 6 cm in width was cut out from the knitted fabric. And as electrodes, two tape-like conductors similar to those in Example 1 were prepared. Next, on the sample, two electrodes similar to those in Example 1 were arranged such that the horizontal direction of the sample and the length direction of the electrodes were parallel, and the ends in the width direction of the electrodes were spaced 12 cm apart, and fixed to the sample by sewing with polyester yarn to obtain a net-like heating element. Each electrode was arranged so as to protrude 0.5 cm in the length direction and 1.5 cm in the width direction from the sample.

[0086] (Comparative Example 2) It was made different from Example 1 in that no plating was performed on the tricot mesh knitted fabric. And otherwise, in the same manner as in Example 1, a net-like body was obtained.

[0087] (Comparative Example 3) It was made different from Example 1 in that as the core material, only regular polyester fibers were used without using heat-adhesive fibers, and no processing of heat adhesion between the fibers was performed by dry heat treatment. And otherwise, in the same manner as in Example 1, a net-like body was obtained.

[0088] Next, two electrodes were arranged and fixed to the obtained net-like body in the same manner as in Example 1 to obtain a net-like heating element.

[0089] Table 1 shows the measurement and evaluation results of the characteristics of the net-like heating elements of Example 1, Comparative Example 1, and Comparative Example 3, and the net-like body of Comparative Example 2.

[0090] [Table 1]

[0091] The net-like heating element of Example 1 had its intersections connected by the fusion of linear fibers, and the intersection angle between different linear fibers could be changed by elastic deformation. Furthermore, the change in volume resistivity when stretched was small, and heating properties were observed. For this reason, it could be used as a heating element for automobile seats.

[0092] Although the net-like heating element of Comparative Example 1 was capable of tensile elastic deformation in the planar direction, its intersections were not connected. As a result, when elastically deformed, displacement occurred in the longitudinal direction between the linear elements at the intersections. Consequently, the volume resistivity fluctuated greatly when stretched, and the volume resistivity was too low, resulting in insufficient heating. Therefore, it was unsuitable as a heating element for automotive seats.

[0093] Comparing Example 1 with Comparative Example 1, Comparative Example 1 was a regular knitted fabric with a small mesh size, resulting in close contact between the metals. This led to excessively high conductivity, resulting in a low volume resistivity and therefore insufficient heat generation. Furthermore, in Comparative Example 1, variations in conductivity occurred on the surface of the knitted fabric, leading to localized excessive heat generation. One of the five samples evaluated for heat generation characteristics (the sample showing the highest temperature) reached a maximum heat generation temperature of 120°C, making it impractical. On the other hand, Example 1 was a mesh knitted fabric with voids, resulting in somewhat poor conductivity. This increased the volume resistivity, leading to greater heat generation. Moreover, there was no variation in conductivity, and no localized excessive heat generation occurred.

[0094] The net-like material of Comparative Example 2 was constructed by fusing fibers, with linear bodies at their intersections, and the intersection angles between the different linear bodies could be changed by elastic deformation. However, the linear bodies were not conductive. Therefore, no current flowed even when a voltage was applied, and it did not generate heat, making it unsuitable as a heating element for automotive seats.

[0095] Comparing Example 1 with Comparative Example 3, in Comparative Example 3, the intersections of the net-like structures were not connected. As a result, when stretched, the different linear structures shifted relative to each other in the longitudinal direction at the intersections, causing a large change in the volume resistivity. [Industrial applicability]

[0096] The net-like material of the present invention is a material that is capable of elastic deformation in the tensile direction, yet its electrical resistance does not substantially change even when elastically deformed. Therefore, it can be used in various technical fields where such properties are required.

[0097] The net-like heating element of the present invention is made of a material that can undergo elastic deformation in the tensile direction, yet its heating characteristics due to Joule heating do not substantially change even when elastically deformed. For this reason, it can be used not only in the heaters for automobile seats mentioned above, but also in various technical fields where heating elements with such characteristics are required. [Explanation of symbols]

[0098] 11 linear body 11a, 11b, 11c, 11d linear body 12 mesh 13 linear body 14 linear body 15 Intersection 15a, 15b, 15c, 15d intersection θ1 intersection angle θ² intersection angle 16 Core material 17 Metal film 21a, 21b, 21c, 21d, 21e, 21f linear body 25a, 25b, 25c, 25d, 25e, 25f intersection

Claims

1. A net-like material having a mesh structure composed of conductive linear bodies, Each mesh in the aforementioned mesh structure is formed in a polygonal shape by multiple linear bodies and has intersections between different linear bodies. The different linear bodies are connected at the intersection such that no displacement occurs between them in the longitudinal direction of the linear bodies. The aforementioned intersection is a net-like material characterized in that the intersection angle between the different linear bodies can be changed by elastic deformation.

2. The net-like material according to claim 1, characterized in that the linear body is composed of a fibrous material, and the net-like material is composed of the fibrous material woven or knitted in a net-like manner.

3. The net-like material according to claim 2, characterized in that the fibrous material is a heat-bondable fiber.

4. The net-like material according to claim 1, characterized in that the conductive linear body has a core material whose surface is covered with a metal film.

5. The polygonal mesh has multiple intersections between different linear bodies. The net-like material according to claim 1, characterized in that when the intersection angle of different linear bodies at the intersection changes, the distance between separate intersections that are not adjacent to each other in the polygonal shape changes.

6. The net-like material according to claim 5, characterized in that when the intersection angle of different linear bodies changes at an intersection, the amount of change in the distance between a first intersection and a second intersection that are not adjacent to each other in the polygonal shape is greater than the amount of change in the distance between a third intersection that is adjacent to each other in the polygonal shape and the first intersection.

7. In a polygon, there are multiple combinations of intersections that are not adjacent to each other. The net-like material according to claim 5, characterized in that when tensile stress is applied in the planar direction of the net-like material, the elongation of the net-like material along the direction in which at least one pair of intersections that are not adjacent to each other in the polygonal shape are aligned is 3% or more.

8. The net-like material according to claim 4, characterized in that the metal film consists of at least one of a copper film, a nickel film, a tin film, a silver film, and an aluminum film.

9. The net-like material according to claim 1, characterized in that its volume resistivity is 5.0 to 120.0 Ω.

10. The net-like material according to claim 9, characterized in that the volume resistivity is 3.5 to 150.0 Ω when the elongation of the net-like material along the direction in which non-adjacent intersections in the polygonal shape are aligned is 3%.

11. A net-like heating element characterized by being composed of a net-like material as described in any one of claims 1 to 10.

12. The net-like heating element according to claim 11, characterized by having a pair of electrodes arranged at a distance from each other in the planar direction of the net-like material.

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