JP2023105727A - Planar heating material and planar heating element - Google Patents

Abstract

To provide a planar heating material excellent in rapid warming property while having good surface followability to an object to be heated even when a metal wire is used as a conductive thread.SOLUTION: In a planar heating material 10 including a stretchable base material and a conductive thread 100, the conductive thread 100 is a metal wire coated with an insulating resin, and the length La of the conductive thread 100 is set to 2.5 times or more with respect to the unit length Ls of the base material, and the constant load elongation rate is 20% or more when a load of 3 N measured in accordance with the elongation rate (D method) of JIS L1096 is applied.SELECTED DRAWING: Figure 4

Description

TECHNICAL FIELD The present invention relates to a planar heat-generating material including a stretchable base material and conductive threads, and a planar heat-generating body using the planar heat-generating material.

Planar heating elements are widely used, for example, in interior parts of vehicles, clothing, health/nursing/medical equipment, and furniture.

As this type of planar heating element, a sheet-like product in which a polyester film or the like is used as a base material and the heating element is attached to the base material has been widely used (see, for example, Patent Document 1).

In recent years, the applications of planar heating elements have diversified, and more and more planar heating elements are installed not only on flat surfaces of objects to be heated, but also on curved and uneven surfaces. Heating elements with a shape are required to have surface followability that can follow surfaces of various shapes.

WO2016/024610

However, the planar heating element of Patent Document 1 is flexible but poor in stretchability and insufficient in surface conformability to curved portions and uneven portions of an object to be heated.

In addition, sheet heating elements using metal wires as conductive yarns are also required to generate heat in a short period of time (quick warming property).

The present invention has been made in view of the above problems, and even if a metal wire is used as the conductive thread, it has excellent surface followability to the object to be heated and excellent rapid warming property. An object of the present invention is to provide a planar heating material and a planar heating element.

The characteristic configuration of the planar heat generating material according to the present invention for solving the above problems is as follows:
A planar heating material comprising a stretchable base material and a conductive thread,
The conductive thread is a metal wire coated with an insulating resin,
The length of the conductive thread is set to 2.5 times or more with respect to the unit length of the base material,
Constructed so that the constant load elongation rate (hereinafter also referred to as "3N constant load elongation rate") when a load of 3N measured in accordance with the elongation rate (D method) of JIS L1096 is applied is 20% or more. It is in what is being done.

According to the planar heat generating material of this configuration, it is configured to include a base material having stretchability and a conductive thread, which is a metal wire coated with an insulating resin, and this unit length for the unit length of the base material By setting the length of the conductive thread contained in the base material of the length to be 2.5 times or more, in the conductive thread, the excess length portion that is longer than the unit length of the base material, that is, the elongation generation can be fully present. When the substrate is stretched, the conductive yarn is stretched so that the stretch allowance of the conductive yarn is reduced. On the other hand, when the elongation of the base material is released, the elongation of the conductive material, which had decreased due to the contraction of the base material, recovers. In this way, the planar heat generating material as a whole has stretchability. By setting the 3N constant load elongation rate of the sheet heat generating material to 20% or more, the stretchability can make the sheet heat generating material conform well to the shape of the object to be heated and deform it. In addition, since the metal wire included in the conductive yarn is elongated by the amount of elongation of the conductive yarn, it is possible to efficiently heat the object to be heated in a short time, resulting in excellent rapid heating. Therefore, the planar heat generating material of the present invention, even if it uses a metal wire as the conductive yarn, has excellent surface conformability to the object to be heated and excellent rapid warming property. In addition, by setting the length of the conductive thread to 2.5 times or more with respect to the unit length and setting the 3N constant load elongation rate to 20% or more, the planar heat generating material has excellent stretchability. In addition, the bending durability is also excellent.

In the planar heating material according to the present invention,
It is preferable that the conductive thread is sewn onto the base material at intervals of 10 mm or less.

According to the planar heat generating material of this configuration, since the conductive thread is sewn on the base material at intervals of 10 mm or less, the number of conductive threads per unit area in the planar heat generating material increases. The heat-generating material has improved rapid warming properties.

In the planar heating material according to the present invention,
The conductive thread is preferably sewn directly onto the base material.

According to the planar heat generating material of this configuration, since the conductive thread is sewn directly onto the base material, there is no need to interpose another member, making the planar heat generating material easy to manufacture. become a thing. In addition, since the conductive thread is more reliably fixed to the base material, the planar heat generating material has excellent durability.

In the planar heating material according to the present invention,
further comprising an insulating thread sewn directly onto the substrate;
It is preferable that the conductive thread is sewn indirectly to the base material by passing the conductive thread through a gap between the seam of the insulating thread and the base material.

According to the planar heat generating material of this configuration, the conductive thread is passed through the gap between the seam of the insulating thread sewn directly to the base material and the base material, so that the conductive thread is applied to the base material. can be sewn indirectly in any direction. As a result, it is possible to increase the number of conductive threads located on the surface of the planar heating material, thereby improving the quick warming property of the planar heating material.

In the planar heating material according to the present invention,
The conductive thread preferably has a diameter of 100 μm or less.

According to the planar heat generating material of this configuration, since the diameter of the conductive thread is 100 μm or less, the conductive thread is easily bent. Become.

In the planar heating material according to the present invention,
The base material is preferably a base fabric composed of two layers or less of knitted fabric.

According to the planar heat generating material of this configuration, since the base material is a base fabric composed of two layers or less of knitted fabric, the elasticity of the base material is improved. The heat generating material also has improved surface followability.

In the planar heating material according to the present invention,
The substrate preferably has a constant load elongation rate (3N constant load elongation rate) of 50% or more when a load of 3N is applied, which is measured according to the elongation rate (D method) of JIS L1096.

According to the planar heat generating material of this configuration, the base material has sufficient stretchability because the 3N constant load elongation rate of the base material is 50% or more. , has sufficient elasticity.

In the planar heating material according to the present invention,
The conductive yarn preferably has an electrical resistivity of 5×10 ⁻⁵ Ω·m or less.

According to the planar heating material of this configuration, by using a conductive yarn having an electrical resistivity of 5 × 10 ^-5 Ω·m or less, the temperature rise speed of the conductive yarn increases, and it is excellent in quick warming. It is possible to realize a planar heating material.

The characteristic configuration of the planar heating element according to the present invention for solving the above problems is as follows:
A planar heating element in which an electrode is provided on any one of the planar heating materials described above,
The conductive thread is processed so that the metal wire is exposed in the area where the electrode is installed in the planar heat generating material.

According to the planar heating element of this configuration, since the planar heating material of the present invention is used, the surface conformability to the object to be heated is good, and the heat is generated in a short time. A planar heating element can be realized. Here, since the planar heating element is processed so that the metal wires of the conductive threads are exposed in the area where the electrodes are installed in the planar heating element, the electrical connection between the electrodes and the conductive threads is ensured, and The insulating resin prevents short-circuiting of the conductive yarns located at , and both excellent rapid warming property and high safety can be achieved.

FIG. 1 is a perspective view schematically showing a sheet heating element according to a first embodiment of the invention. FIG. 2 is a cross-sectional view of a planar heating material used in the planar heating element according to the first embodiment of the present invention, and schematically shows a state of sewing conductive thread to a base material. FIG. 3 is an explanatory diagram showing the diameter of the conductive thread. FIG. 4 is a plan view of a sheet heating material used in the sheet heating element according to the first embodiment of the present invention, showing a state in which no load is applied. FIG. 5 is a plan view of a sheet heating material used in the sheet heating element according to the first embodiment of the present invention, showing a state in which a load is applied. FIG. 6 is a plan view of a planar heating material used in the planar heating element according to the second embodiment of the present invention, showing a state in which no load is applied. FIG. 7 is a plan view of a planar heating material used in the planar heating element according to the second embodiment of the present invention, showing a state in which a load is applied.

A planar heating material and a planar heating element of the present invention will be described with reference to the drawings. However, the configuration shown in each figure (the state of the conductive thread sewn onto the base material) is exaggerated or simplified as appropriate for ease of explanation. , the actual sheet heating material and sheet heating element may not be accurately reflected.

[First embodiment]
<Planar heating element>
FIG. 1 is a perspective view schematically showing a sheet heating element 1 according to the first embodiment of the invention. The planar heating element 1 is formed by providing electrodes 20 in two installation areas 10a separated in the course direction (latitudinal direction) of the planar heating material 10, which will be described in detail later. The planar heat-generating material 10 is formed by sewing the conductive thread 100 along the course direction (the weft direction) to the base material (the front base material 200 and the back base material 300). Due to the elasticity of 300, the shape of the object to be heated can be well followed and deformed. As will be described later, the conductive thread 100 includes a metal wire coated with an insulating resin, and in the installation region 10a, the insulating resin is removed by physical processing such as laser removal processing, chemical processing, or the like, and the metal wire is removed. Processed to expose lines.

The electrodes 20 are electrically connected to a plurality of conductive threads 100 arranged in parallel in the well direction (warp direction) in each installation region 10a. When a voltage is applied between the two electrodes 20, the planar heating element 1 can generate Joule heat in the conductive thread 100 that conducts between the electrodes, thereby heating and retaining the temperature of the object to be heated. Note that the object to be heated is, for example, an interior part of a vehicle such as a steering wheel or a seat. The planar heating element 1 is used so as to cover the surface of an object to be heated.

The electrode 20 is configured, for example, as a conductive film in which metal is deposited on the surface of a resin film such as a polyimide film, or as a film in which a metal foil is attached. The electrode 20 is attached to each of two installation regions 10a of the planar heat-generating member 10, which are spaced apart in the weft direction. In the installation region 10a, the conductive thread 100 is processed such that the insulating resin 120 on the surface of the conductive thread 100 is removed by laser removal processing or the like, and the metal wire 110 is exposed. Therefore, the electrode 20 is electrically connected to the conductive thread 100 in the installation area 10a. Examples of metals deposited on resin films include aluminum, nickel, copper, titanium, magnesium, tin, zinc, iron, silver, gold, platinum, vanadium, molybdenum, tungsten, chromium, manganese, silicon, lead, bismuth, and boron. , germanium, arsenic, antimony, tellurium, and cobalt, as well as alloys thereof, can be used. Among these, copper and tin are preferably used.

The planar heating element 1 has a rapid warming property in which the time required for the surface temperature to reach 65° C. is within 90 seconds when electricity is supplied while the surface temperature is kept at 25° C., as an index of the rapid warming property. is preferred, and reaching 65°C within 70 seconds is more preferred. If it has such a rapid warming property, it can be suitably used for interior parts of vehicles such as steering wheel heaters and seat heaters.

<Planar heating material>
FIG. 2 is a cross-sectional view of a sheet heating material 10 used in the sheet heating element 1 according to the first embodiment. This cross-sectional view schematically shows a state in which the conductive thread 100 is sewn onto the substrates (front substrate 200 and back substrate 300). The planar heat generating material 10 is configured as a multi-base material having, for example, an insulating front base material 200 and an insulating back base material 300 . The planar heat-generating material 10 may be configured as a triple or more multiple base material having another base material between the front base material 200 and the back base material 300. Dual substrates are preferred for performance.

The conductive thread 100 may be sewn on at least one of the front base material 200 and the back base material 300, and is sewn on both of them in the example of FIG. In the course direction or well direction (here, well direction) of at least one of the front substrate 200 and the back substrate 300, the conductive yarns 100 are preferably arranged so as not to be adjacent to each other. In the example of FIG. 2, the conductive thread 100 penetrates the front substrate 200 and the back substrate 300 and sews directly to form a loop inside the front substrate 200 and the back substrate 300. attached.

When a load is applied, for example, in the weft direction to the planar heat-generating material 10 in an unloaded state as shown in FIG. At that time, the loop (elongation margin) of the conductive yarn 100 inside the front substrate 200 and the back substrate 300 becomes smaller, and the exposed portion of the conductive yarn 100 becomes longer accordingly. In this way, the exposed portions of the conductive yarns 100 are elongated in the load direction (the apparent length is increased) following the elongation of the front base material 200 and the back base material 300, so that the planar heat generating material 10 is not subjected to the load. direction (from the state of FIG. 4 to the state of FIG. 5).

On the other hand, when the load applied to the planar heat generating material 10 is released, the front base material 200 and the back base material 300 contract, and at that time, the inside of the front base material 200 and the back base material 300 becomes smaller. The loop of the conductive thread 100 is restored, and the exposed portion of the conductive thread 100 is shortened accordingly. In this way, the exposed portions of the conductive yarns 100 are shortened in the load direction (the apparent length is reduced) following the contraction of the front base material 200 and the back base material 300, so that the planar heat generating material 10 is flattened in the weft direction. direction (from the state of FIG. 5 to the state of FIG. 4).

In this manner, the conductive thread 100 is sewn to the front base material 200 and the back base material 300 so as to form a loop inside them, so that the planar heat generating material 10 has stretchability.

<Base material>
The front base material 200 and the back base material 300 as base materials are base materials having stretchability. The front base material 200 and the back base material 300 are not particularly limited as long as they have elasticity, and specific examples include knitted fabrics, woven fabrics, films, nonwoven fabrics, urethane sponges, and the like. Among these, knitted fabrics are preferable from the viewpoint of stretchability. As the knitted fabric, weft knitting is preferable from the viewpoint of stretchability, and circular knitting is preferable from the viewpoint of productivity and economy. When the front base material 200 and the back base material 300 are knitted fabrics, the planar heat generating material 10 is a connecting thread (Fig. not shown). In this way, the substrates (the front substrate 200 and the back substrate 300) of the planar heat-generating material 10 are composed of two layers or less of knitted fabric, so that the substrates (the front substrate 200 and the back substrate 300) has relatively excellent stretchability, and the planar heat generating material 10 has improved surface followability.

The 3N constant load elongation rate of the front substrate 200 and the back substrate 300 is preferably 50% or more, more preferably 70% or more, and even more preferably 90% or more. Since the 3N constant load elongation rate is 50% or more, the front base material 200 and the back base material 300 have sufficient stretchability, and accordingly the planar heating material 10 also has sufficient stretchability. will have The 3N constant load elongation rate of the front base material 200 and the back base material 300 is evaluated as the 3N constant load elongation rate as a whole.

When the front base material 200 and the back base material 300 are knitted fabrics, examples of forms of ground yarns constituting these fabrics include spun yarns (short fiber yarns), multifilament yarns, monofilament yarns, and the like. The multifilament yarn may optionally be twisted or subjected to processing such as false twisting or fluid disturbance treatment. The fineness (total fineness) of the base yarn is preferably 330 dtex or less, more preferably 167 dtex or less, and even more preferably 84 dtex or less. The fineness (total fineness) of the ground thread is preferably 56 dtex or more. If the total fineness of the threads used as base threads is 330 dtex or less, the base structure of the front base material 200 and the back base material 300 will be flexible, and the planar heating material 10 will have excellent surface followability. . Further, if the fineness (total fineness) of the base threads is 56 dtex or more, the planar heat generating material 10 has excellent bending durability.

There are no particular restrictions on the material of the fibers that make up the ground threads, and examples include natural fibers, regenerated fibers, semi-synthetic fibers, synthetic fibers, and the like. These can be used alone or in combination of two or more. Among them, synthetic fibers are preferable, polyester fibers such as polyethylene terephthalate are preferable, and cationic dyeable polyester fibers (CDP) are more preferable, because they have excellent strength. The shape of the fibers is not particularly limited, and may be either long fibers or short fibers. In addition, the cross-sectional shape of the fiber is not particularly limited. good too.

<Conductive thread>
FIG. 3 is an explanatory diagram showing the detailed configuration of the conductive thread 100. As shown in FIG. The conductive thread 100 has a metal wire 110 and an insulating resin 120 covering the metal wire 110 .

As the diameter R of the conductive thread 100 becomes smaller, the conductive thread 100 becomes more likely to bend, which facilitates sewing (improves sewability) and improves the surface conformability, while the conductive thread 100 is more likely to break. Therefore, it tends to be difficult to sew (poor sewability). In addition, the larger the diameter R of the conductive thread 100, the more quickly the conductive thread 100 warms, and the more difficult the conductive thread 100 is to break, while the more difficult the conductive thread 100 is to bend, which makes sewing itself difficult. , the bending durability tends to decrease. Considering these tendencies, the diameter R of the conductive thread 100 is preferably 100 μm or less, more preferably 20 to 80 μm, even more preferably 20 to 50 μm. If the diameter R of the conductive thread 100 is within the above range, the planar heat generating material 10 will have rapid warming properties, surface conformability, bending durability, and sewability. Here, the diameter R of the conductive thread 100 means the maximum diameter, and is specifically calculated as the sum of the diameter of the metal wire 110 and the thickness (×2) of the insulating resin 120 .

The diameter of the metal wire 110 can be appropriately set so that the diameter R of the conductive thread 100 described above falls within the above range. Considering this point of view, the diameter of the metal wire 110 is preferably 20 to 80 μm, more preferably 20 to 50 μm. Here, the diameter of the metal wire 110 means the maximum diameter.

Materials of the metal wire 110 include, for example, aluminum, nickel, copper, titanium, magnesium, tin, zinc, iron, silver, gold, platinum, vanadium, molybdenum, tungsten, chromium, manganese, silicon, lead, bismuth, boron, and germanium. , arsenic, antimony, tellurium, and cobalt, and alloys thereof can be used. Among them, copper and nickel, copper and silicon, copper and alloys such as manganese, alloys of copper and tin, and nichrome are preferably used. It should be noted that the conductive thread 100 may be carbon fiber instead of the metal wire 110 coated with the insulating resin 120 .

The insulating resin 120 protects the metal wire 110, ensures insulation, and prevents disconnection of the metal wire 110 due to bending or the like. The insulating resin 120 is made of a material that can be easily removed by a laser removal process or the like (a material that can be melted by heating) in order to enable electrical continuity between the metal wires 110 and the electrodes 20 in the area 10a where the planar heat generating material 10 is installed. materials) are used. As a material of such insulating resin 120, a synthetic resin is preferable, and from the viewpoint of bending resistance, oil resistance, abrasion resistance, and toughness, a thermoplastic elastomer (TPE) is more preferable, and an ester imide is preferable. More preferred. The thickness of the insulating resin 120 is preferably 4-8 μm. If the thickness of the insulating resin 120 is within the above range, the bending durability and flexibility of the conductive thread 100 will be favorable. In particular, when the thickness of the insulating resin 120 is 4 μm or more, the metal wire 110 is sufficiently protected. In addition, since the thickness of the insulating resin 120 is 8 μm or less, it is possible to suppress the conductive thread 100 from becoming too hard. Complete removal of the insulating resin 120 is facilitated.

The conductive yarn 100 preferably has an electrical resistivity of 5×10 ⁻⁵ Ω·m or less, more preferably 5×10 ⁻⁷ Ω·m or less. Since the electrical resistivity of the conductive yarn 100 is 5×10 ⁻⁵ Ω·m or less, the planar heating material 10 with a size of about 40 cm in the weft direction is used for interior parts of vehicles such as steering wheel heaters and seat heaters. 3, when a voltage of, for example, 13 V is applied from an in-vehicle battery, an appropriate amount of Joule heat is generated to increase the temperature rise rate of the planar heating material 10, resulting in excellent rapid warming.

FIG. 4 is a plan view of the planar heating material 10, showing a state in which no load is applied. As shown in FIGS. 2 and 4, the conductive yarn 100 is applied along the weft direction to the front base material 200 and the back base material 300 (see FIG. 2), which are knitted fabrics, so as to form loops inside them. directly sewn. A sewing method for forming a loop is not particularly limited, and a known sewing method can be adopted.

Since the conductive thread 100 is directly sewn to form a loop, the length La of the conductive thread 100 is the unit of the front base material 200 and the back base material 300 (see FIG. 2). The length is set to be at least 2.5 times the length Ls (La/Ls≧2.5). That is, the length La of the conductive thread 100 included in the front base material 200 and the back base material 300 having the unit length Ls is set to be 2.5 times or more the unit length Ls. Since the length La of the conductive thread 100 is set to be 2.5 times or more the unit length Ls, in the conductive thread 100, the unit length Ls of the front base material 200 and the back base material 300 A surplus length portion that is longer than , that is, a sufficient amount of elongation can be allowed to exist. When the front base material 200 and the back base material 300 are elongated, the conductive yarn 100 is elongated so that the elongation margin of the conductive yarn 100 is reduced as shown in FIG. On the other hand, when the extension of the front base material 200 and the back base material 300 is released, the elongation allowance of the conductive yarn 100 that has decreased due to the contraction of the front base material 200 and the back base material 300 is recovered. In this way, the planar heat-generating material 10 as a whole has elasticity. In addition, since the metal wire 110 included in the conductive yarn 100 is elongated by the amount of elongation of the conductive yarn 100, it is possible to efficiently heat the object to be heated in a short time, and the planar heating material 10 can quickly warm up. become excellent. From the viewpoint of further increasing the 3N constant load elongation rate of the planar heating material 10 and further improving the rapid warming property, the length La of the conductive thread 100 is set to be four times or more the unit length Ls. is preferred. The upper limit of the length La of the conductive thread 100 may be within a range that does not make handling of the planar heat generating material 10 difficult, and can be set, for example, to 7 times or less of the unit length Ls.

The conductive thread 100 is preferably sewn (here, directly) to the front base material 200 and the back base material 300 at an interval S of 10 mm or less, and is sewn at an interval S of 4 mm or less. is more preferable. Since the conductive threads 100 are sewn to the front base material 200 and the back base material 300 at intervals S of 10 mm or less, the number of conductive threads 100 per unit area in the planar heat generating material 10 increases. The heat-generating material 10 has improved quick-warming properties. The conductive threads 100 are preferably sewn at intervals S of 10 mm or less when the planar heat generating material 10 is applied with a load of 3 N or when there is no load. The distance S between the conductive yarns 100 means the distance between adjacent conductive yarns 100 .

In the example of FIG. 4, the exposed portions of the conductive thread 100 are arranged parallel to each other, but the arrangement and pattern are not particularly limited. may be appropriately set so that is a desired value of 20% or more.

The length of the exposed portion of the conductive yarn 100 under no load and the length of the portion forming the loop are the length La of the conductive yarn 100 with respect to the unit length Ls of the front substrate 200 and the back substrate 300. It can be appropriately set so that the desired value is 2.5 times or more and the 3N constant load elongation rate of the sheet heating material 10 is 20% or more.

<3N Constant Load Elongation Rate of Sheet Heating Material>
FIG. 5 is a plan view of the planar heat generating material 10, showing a state in which a load is applied. The planar heating material 10 is configured to have a 3N constant load elongation rate of 20% or more. The 3N constant load elongation rate of the planar heating material 10 is more preferably 40% or more. The upper limit of the 3N constant load elongation rate is not particularly limited, and can be set as appropriate, for example, 100%.

Here, the 3N constant load elongation rate (%) of the sheet heat generating material 10 when the load F is 3N is the length K1 of the sheet heat generating material 10 in the state where no load is applied, and the load of 3N. is expressed by the following formula (1) using the length K2 of the planar heat generating material 10 in the state where is given.
3N constant load elongation rate (%) = {(K2-K1) / K1} × 100 (1)

By setting the 3N constant load elongation rate of the planar heat generating material 10 to 20% or more, the planar heat generating material 10 can be deformed to conform well to the shape of the object to be heated. Furthermore, as described above, the length of the metal wire 110 included in the conductive yarn 100 is increased by the amount of elongation of the conductive yarn 100, so that the object to be heated can be efficiently heated in a short time, and the heating is excellent. becomes. Therefore, even when the conductive thread 100 and the metal wire 110 are used, the planar heat generating material 10 has good surface followability to the object to be heated and also has excellent rapid warming property. Further, as described above, the length La of the conductive thread 100 is set to 2.5 times or more with respect to the unit length Ls, and the 3N constant load elongation rate of the planar heating material 10 is set to 20% or more. As a result, the planar heat generating material 10 not only has excellent stretchability, but also has excellent bending durability.

<Characteristics of sheet heating material>
The bending resistance of the planar heating material 10 measured according to JIS L1096 8.21 bending resistance A method (45° cantilever method) is preferably 50 mm or less. Since the bending resistance of the planar heat generating material 10 is 50 mm or less, the followability of the planar heat generating material 10 is improved.

<Manufacturing method of planar heating material>
In the planar heat generating material 10, for example, the front base material 200 and the back base material 300 (see FIG. 2) are stretched in one direction (here, the weft direction), and in this state, the front base material 200 and the back base material 300 are stretched. After sewing the conductive thread 100 so as to form a loop inside, the application of the load can be released. The degree of elongation of the front base material 200 and the back base material 300 at the time of sewing is set to a desired value in which the length La of the conductive thread 100 is 2.5 times or more the unit length Ls of the front base material 200 and the back base material 300. and the 3N constant load elongation rate of the planar heat generating material 10 is set to a desired value of 20% or more.

[Second embodiment]
<Planar heating element>
6 and 7 are plan views of a sheet heat generating material 10 used in a sheet heat generating element according to a second embodiment of the present invention. These plan views show a state in which no load is applied (FIG. 6) and a state in which a load is applied (FIG. 7). The planar heating element according to the second embodiment of the present invention is the planar heating element 1 according to the first embodiment, in which the conductive threads 100 contained in the planar heating element 10 are attached to the front substrate 200 and the back substrate 300. Instead of being directly sewn (see FIG. 2), the insulating thread 400 is sewn directly through which the conductive thread 100 is sewn indirectly. Other configurations (electrodes 20, etc.) are the same as those of the planar heating element 1 according to the first embodiment. The characteristics of the sheet heating element according to the second embodiment are also the same as those of the sheet heating element 1 according to the first embodiment.

<Planar heating material>
As shown in FIG. 6, in the planar heat-generating material 10 of the present embodiment, insulation A thread 400 is sewn directly and stretchably along one direction (the weft direction here) by a known sewing method. The insulating threads 400 are sewn on the front base material 200 and the back base material 300 so as to be positioned parallel to each other. The plurality of conductive yarns 100 are formed on the exposed surface of the planar heat generating material 10 (here, the surface of the front substrate 200 (see FIG. 2)) so that each conductive yarn 100 undulates in the warp direction and extends in the weft direction. The adjacent conductive threads 100 are arranged so that the seams of the insulating threads 400 and the front base material 200 (Fig. 2). Each conductive thread 100 is bent by being passed through two stitches located adjacent to each other in the weft direction (horizontal direction in FIG. 6) of one insulating thread 400, and then in the warp direction of the one insulating thread 400. Insulating threads 400 adjacent in the vertical direction in FIG. 6 are bent by being passed through two stitches adjacent to each other in the weft direction (horizontal direction in FIG. 6). It has a wavy shape.

When a load is applied to the planar heat generating material 10 in an unloaded state as shown in FIG. 6, the front base material 200 and the back base material 300 are elongated as shown in FIG. 7, which will be described later. As the amplitude of the waveform 100 decreases, the period increases (the margin for elongation decreases), and the conductive yarn 100 lengthens in the weft direction accordingly. In this way, the conductive thread 100 becomes longer in the load direction (the apparent length becomes longer) following the elongation of the front base material 200 and the back base material 300, so that the planar heat generating material 10 is elongated in the load direction. will be

On the other hand, when the load (see FIG. 7) applied to the planar heat generating material 10 is released, the front base material 200 and the back base material 300 contract, and at that time, the amplitude of the waveform of the conductive thread 100 decreases. In addition, the increased period is recovered (the elongation allowance is recovered), and the conductive yarn 100 is shortened in the weft direction accordingly. In this way, following the contraction of the front base material 200 and the back base material 300, the conductive yarn 100 shortens in the load direction (the apparent length becomes smaller), so the planar heat generating material 10 contracts in the load direction. (See Figure 6).

In this way, the conductive thread 100 is indirectly sewn to the front base material 200 and the back base material 300 so as to form a wave shape, so that the planar heat generating material 10 has stretchability.

<Base material>
As the base material, the same base material as used in the above-described first embodiment can be used. In addition, as in the first embodiment described above, the base material is preferably a base fabric composed of a knitted fabric having two or less layers from the viewpoint of stretchability, and such a base fabric is shown in FIG. As described above, a multi-layer knitted fabric using a front knitted fabric as the front base material 200 and a back knitted fabric as the back base material 300 can be used.

<Insulating thread>
The insulating thread 400 directly sewn on the front base material 200 and the back base material 300 is not particularly limited and can be set as appropriate. The insulating thread 400 may be polyethylene terephthalate thread, for example. The thickness of the insulating thread 400 is preferably finer than 30, more preferably finer than 60, and even more preferably finer than 80. The thickness of the insulating thread 400 can be made thicker than 120, for example. Since the thickness of the insulating thread 400 is finer than 30 count, the insulating thread 400 can be easily sewn to the front base material 200 and the back base material 300 . In addition, since the thickness of the insulating thread 400 is thicker than the 120 count, the durability of the insulating thread 400 can be improved.

The insulating thread 400 follows the expansion and contraction of the front base material 200 and the back base material 300, and by this following, the 3N constant load elongation rate of the planar heating material 10 is a desired value of 20% or more. are sewn directly to the front substrate 200 and the back substrate 300 using known sewing methods.

<Conductive thread>
As the conductive thread 100, the same conductive thread 100 as used in the above-described first embodiment can be used (see FIG. 3).

As described above, the conductive thread 100 is pierced between the seams of the insulating thread 400 and the front base material 200 (see FIG. 2) to form waves in the warp direction and extend in the weft direction. In addition, adjacent conductive yarns 100 are arranged with their waveforms out of phase so that they intersect at the protruding ends of the waveforms.

In this way, by indirectly sewing the conductive thread 100 to form a wave, the length La of the conductive thread 100 is the same as that of the first embodiment described above. The length is set to 2.5 times or more the unit length Ls (see FIG. 2) (La/Ls≧2.5). That is, the length La of the conductive thread 100 included in the front base material 200 and the back base material 300 having the unit length Ls is set to be 2.5 times or more the unit length Ls. Since the length La of the conductive thread 100 is set to be 2.5 times or more the unit length Ls, in the conductive thread 100, the unit length Ls of the front base material 200 and the back base material 300 A surplus length portion that is longer than , that is, a sufficient amount of elongation can be allowed to exist. When the front base material 200 and the back base material 300 are elongated, the conductive yarn 100 is elongated so that the elongation margin of the conductive yarn 100 is reduced, as shown in FIG. On the other hand, when the extension of the front base material 200 and the back base material 300 is released, the elongation allowance of the conductive yarn 100 that has decreased due to the contraction of the front base material 200 and the back base material 300 is recovered. In this way, the planar heat-generating material 10 as a whole has elasticity. In addition, since the metal wire 110 included in the conductive yarn 100 is elongated by the amount of elongation of the conductive yarn 100, it is possible to efficiently heat the object to be heated in a short time, and the planar heating material 10 can quickly warm up. become excellent. From the viewpoint of further increasing the 3N constant load elongation rate of the planar heating material 10 and further improving the rapid warming property, the length La of the conductive thread 100 is set to be four times or more the unit length Ls. is preferred. The upper limit of the length La of the conductive thread 100 can be set to, for example, 7 times or less of the unit length Ls, as in the first embodiment.

As in the first embodiment described above, the conductive thread 100 is preferably sewn indirectly to the front base material 200 and the back base material 300 at a spacing S of 10 mm or less, and at a spacing S of 4 mm or less. More preferably, it is sewn indirectly. The number of conductive threads 100 per unit area in the planar heat generating material 10 is increased by indirectly sewing the conductive threads 100 to the front base material 200 and the back base material 300 at intervals S of 10 mm or less. Therefore, the planar heat-generating material 10 has improved quick-warming properties. The conductive threads 100 are preferably sewn indirectly at intervals S of 10 mm or less in a state where a load of 3 N is applied to the planar heating material 10 or in a state where no load is applied. The distance S between the conductive yarns 100 means the distance between adjacent conductive yarns 100 . Specifically, as shown in FIG. 6, in the present embodiment, the spacing S between the conductive threads 100 is the spacing between the protruding ends of the corrugations of the conductive threads 100 located next to each other. Further, by adjusting the spacing between the insulating threads 400, the spacing S between the conductive threads 100 can be adjusted.

The amplitude and period of the waveform in the conductive yarn 100 are such that the length La of the conductive yarn 100 is 2.5 times or more the unit length Ls of the front substrate 200 and the back substrate 300, and , so that the 3N constant load elongation rate of the planar heating material 10 is a desired value of 20% or more.

The arrangement and pattern of the conductive threads 100 on the exposed surface of the planar heat generating material 10 are not limited to the example shown in FIG. It may be set appropriately so that

<3N Constant Load Elongation Rate of Sheet Heating Material>
FIG. 7 is a plan view showing a state in which a load is applied to the planar heat generating material 10. FIG. As in the first embodiment described above, the planar heat generating material 10 is configured so that the 3N constant load elongation rate is 20% or more. The 3N constant load elongation rate is more preferably 40% or more. The upper limit of the 3N constant load elongation rate is not particularly limited, and can be set as appropriate, for example, 100%.

The constant load elongation rate (%) of the planar heat generating material 10 when the load F is 3N is expressed in the same manner as the formula (1) explained in the first embodiment.

<Characteristics of sheet heating material>
As in the first embodiment described above, the bending resistance of the sheet heating material 10 measured according to JIS L1096 8.21 bending resistance A method (45° cantilever method) is preferably 50 mm or less. Since the bending resistance of the planar heat generating material 10 is 50 mm or less, the followability of the planar heat generating material 10 is improved.

<Manufacturing method of planar heating material>
The planar heat generating material 10 includes, for example, insulating yarns 400 on the front substrate 200 and the back substrate 300 (see FIG. 2), and the insulating yarns 400 can be stretched inside or on the back side of the front substrate 200 and the back substrate 300. and when sewing to the front base material 200, the conductive thread 100 is covered with a seam (the conductive thread 100 is penetrated between the seam and the front base material 200), while the weft direction It can be manufactured by sewing sequentially towards the The length of the seam of the insulating thread 400 and the amplitude and period of the waveform of the conductive thread 100 at the time of sewing are such that the length La of the conductive thread 100 with respect to the unit length Ls of the front base material 200 and the back base material 300 is 2 5 times or more, and the 3N constant load elongation rate of the planar heat generating material 10 may be appropriately set to a desired value of 20% or more.

Sheet heat generating materials (Examples 1 to 17) having the characteristic configuration of the present invention were produced, and various measurements and evaluations were performed. For comparison, planar heat generating materials (Comparative Examples 1 and 2) not having the characteristic configuration of the present invention were produced, and similar measurements and evaluations were performed. The measurement and evaluation items were 3N constant load elongation rate, bending resistance, rapid warming property, surface followability, bending durability, and sewability. Each item will be described below.

[3N constant load elongation rate]
The 3N constant load elongation rate was measured according to D method (constant load method for knitted fabrics) of "8.16.1 Elongation rate" of "JIS L1096 Woven and knitted fabric test methods". Specifically, a test piece with a length of 40 mm and a width of 70 mm was taken from a base material or a planar heating material, and one end (40 mm in width) of the test piece in the weft direction was clamped and fixed with a clip. The chuck interval (mm) was measured when the end was pulled at 3N (a constant load of 3N was applied) using a spring balance, and the 3N constant load elongation rate (%) was calculated based on the following formula.
3N constant load elongation rate (%) = {(distance between chucks when 3N load is applied) / 50} x 100

[Bending resistance]
The bending resistance was measured according to the A method (45° cantilever method) of "8.21 Bending resistance" of "JIS L1096 Woven and knitted fabric test methods". A test piece of 20 mm × 150 mm is taken from the planar heating material in the warp and weft directions, placed on a cantilever type tester with a 45° slope so that the short side of the test piece is aligned with the base line of the scale, and measured in the direction of the slope. slid gently. When the center point of one end of the test piece touched the slope, the position of the other end was read on the scale, and the length (mm) of movement of the test piece was determined as the bending resistance.

[rapid warming]
The rapid warming property was measured by the following procedure. A test piece of 3.5 cm in the warp direction and 11 cm in the weft direction was taken from the planar heating material, and the insulating resin was removed by applying laser removal processing to the area of 2 cm on both ends in the weft direction, and the metal wire was exposed. formed a region. An electrode made of a conductive film of 5 cm×2 cm was attached to each installation area to form a planar heating element. The test piece was covered with synthetic leather (trade name: Leatherby B-1000, manufactured by Masuda Co., Ltd., thickness: 0.78 mm), and the temperature of the synthetic leather surface was measured with a thermography (FLIR product number: FLIR C2). This test piece was placed in an environment of 25° C., a voltage of 5 V was applied between the electrodes, and the time until the measured temperature by thermography reached 65° C. was measured. Then, the rapid warming property was evaluated according to the following evaluation criteria.
++: Less than 70 seconds +: 70 seconds or more, less than 90 seconds -: 90 seconds or more

[Surface followability]
A planar heating material was fixed along the surface of a trapezoidal box, and the presence or absence of wrinkles and lifting of the fabric from the surface of the box was visually observed. Then, the surface followability was evaluated according to the following evaluation criteria.
++: No lifting or wrinkling of the fabric.
+: There are wrinkles, but there is no lifting of the fabric.
- : The fabric floated up from the surface of the box.

[Bending durability]
A test piece of 25 mm in the warp direction and 200 mm in the weft direction was taken from the planar heating material, and the test piece was repeatedly bent at the center in the weft direction so that both ends of the test piece in the weft direction were brought together. Every time the test piece was bent 1000 times, the presence or absence of disconnection of the metal wire was confirmed by an electrical test. Then, the bending durability was evaluated according to the following evaluation criteria.
+: No disconnection occurred at 10,000 times of bending.
-: Disconnection occurred when the number of times of bending was less than 10000 times.

[sewingability]
Whether or not it is impossible to sew the conductive thread due to disconnection of the conductive thread when directly or indirectly sewing the conductive thread to the base material, and whether the conductive thread can be sewn without bending the conductive thread. It was visually observed whether attachment was impossible or not. Then, the sewability was evaluated according to the following evaluation criteria.
+: No disconnection of the conductive thread occurred, the conductive thread was bent, and the conductive thread could be sewn.
-: Disconnection of the conductive thread occurred, or the conductive thread was not bent, making it impossible to sew the conductive thread.

<Example 1>
Insulating 84 dtex/36 f polyethylene terephthalate yarn (manufactured by Toray Industries, Inc.) is used as the base yarn of the front weave, the base yarn of the back weave, and the connecting yarn, and a 26 gauge / 33 inch knitting machine (manufactured by Fukuhara Seiki Seisakusho) Double-sided cotton sheeting double knitting (circular knitting) with a course density of 45 (course/25.4 mm) and a well density of 34 (well/25.4 mm) was knitted as a base material (specifically, a base fabric). As shown in Table 1, the 3N constant load elongation of the resulting substrate was 100%.

As the conductive thread, a Cu/Si alloy metal wire with a diameter of 20 μm coated with esterimide (thickness: 6 μm) was used. This conductive thread was sewn directly onto the base material obtained above (sewing 1) as shown in FIG. 4 to obtain the planar heating material of Example 1. In this sewing 1, as shown in Table 1, the length La of the conductive thread included in the unit length Ls (here, 50 mm) of the base material is 281 mm, the ratio (La/Ls) thereof is 5.62 times, The distance S (see FIG. 4) between the conductive threads was set to 4 mm, and the 3N constant load elongation rate of the planar heating material was set to 42%.

<Examples 2 to 5>
The diameter of the metal wire in the conductive thread, the 3N constant load elongation rate of the base material, the length La of the conductive thread included in the unit length Ls (here, 50 mm) of the base material, their ratio (La / Ls), and the surface Sheet heat generating materials of Examples 2 to 5 were obtained in the same manner as in Example 1, except that the 3N constant load elongation rate of the heat generating material was changed as shown in Table 1.

<Example 6>
A base material (base fabric) obtained in the same manner as in Example 1 was used, except that the 3N constant load elongation rate of the base material was set to 95%. As the conductive thread, a metal wire made of a Cu/Si alloy and having a diameter of 50 μm and covered with esterimide (thickness: 6 μm) was used. A 60 count polyethylene terephthalate thread was used as an insulating thread for sewing. Using these base material, conductive thread, and insulating thread for sewing, as shown in FIG. It was sewn indirectly to the base material (Sewing 2) by passing through the fabric, thereby obtaining the planar heat generating material of Example 6. In this sewing 2, as shown in Table 2, the length La of the conductive thread included in the unit length Ls (here, 50 mm) of the base material is 130 mm, the ratio (La/Ls) thereof is 2.60 times, The interval S (see FIG. 6) of the conductive threads was set to 4 mm, and the 3N constant load elongation rate of the planar heating material was set to 62%.

<Examples 7 to 12>
The diameter of the metal wire in the conductive yarn, the 3N constant load elongation rate of the substrate, the length La of the conductive yarn included in the unit length Ls of the substrate, the ratio (La/Ls) of these, and the 3N of the planar heating material Sheet heat generating materials of Examples 7 to 12 were obtained in the same manner as in Example 6, except that the constant load elongation rate was changed as shown in Tables 2 and 3.

<Examples 13 to 17>
The material of the metal wire in the conductive yarn, the electrical resistivity of the conductive yarn, the material of the base material, the 3N constant load elongation rate of the base material, the length La of the conductive yarn contained in the unit length Ls of the base material, the ratio of these ( La/Ls) and the 3N constant load elongation rate of the planar heating materials were changed as shown in Tables 3 and 4 in the same manner as in Example 1 to obtain planar heating materials of Examples 13 to 17. rice field. In Example 17, a urethane elastomer film (trade name: SILKRON (registered trademark) SNCS90 manufactured by Okura Kogyo Co., Ltd., thickness: 100 μm) was used as the base material.

<Comparative Example 1>
The diameter of the metal wire in the conductive thread, the 3N constant load elongation rate of the base material, the length La of the conductive thread included in the unit length Ls (here, 50 mm) of the base material, their ratio (La / Ls), and the surface A planar heating material of Comparative Example 1 was obtained in the same manner as in Example 1, except that the 3N constant load elongation rate of the heating material was changed as shown in Table 4.

<Comparative Example 2>
The 3N constant load elongation rate of the base material, the length La of the conductive thread included in the unit length Ls (here, 50 mm) of the base material, their ratio (La/Ls), and the 3N constant load elongation of the planar heating material A planar heating material of Comparative Example 2 was obtained in the same manner as in Example 6, except that the rate was changed as shown in Table 4.

Tables 1 to 4 show the configurations of the planar heat generating materials of Examples 1 to 17 and the planar heat generating materials of Comparative Examples 1 and 2, as well as the measurement results and evaluation results.

The conductive thread is directly sewn to the base material, the ratio of the length La of the conductive thread to the unit length Ls of the base material (La/Ls) is 2.5 times or more, and the 3N constant load elongation rate In each of the planar heating materials of Examples 1 to 5, in which the is 20% or more, the time required for the measured temperature to reach 65°C was less than 90 seconds, indicating excellent rapid warming properties. All of the planar heat generating materials of Examples 1 to 5 had excellent surface followability, with no fabric floating observed when fixed along a trapezoidal box. All of the planar heat generating materials of Examples 1 to 5 did not break even after being flexed 10,000 times, and had excellent flex durability. In any of the planar heat-generating materials of Examples 1 to 5, when the conductive thread is sewn directly onto the base material, the conductive thread does not break, the conductive thread bends, and the sewing performance of the conductive thread is improved. It was excellent for

The conductive thread is indirectly sewn to the substrate via an insulating thread, and the ratio of the length La of the conductive thread to the unit length Ls of the substrate (La/Ls) is 2.5 times or more, and All of the planar heating materials of Examples 6 to 12, which had a 3N constant load elongation rate of 20% or more, took less than 90 seconds to reach a measured temperature of 65°C, and were excellent in rapid warming. there were. All of the planar heat generating materials of Examples 6 to 12 were excellent in surface conformability, with no lifting of the fabric. All of the planar heat generating materials of Examples 6 to 12 did not break even after being flexed 10,000 times, and had excellent flex durability. In any of the planar heat-generating materials of Examples 6 to 12, when the conductive thread is indirectly sewn onto the base material, the conductive thread does not break, the conductive thread bends, and the sewability of the conductive thread is improved. It was excellent for

Thus, regardless of whether the conductive thread is directly or indirectly sewn onto the substrate, the ratio (La/Ls) of the length La of the conductive thread to the unit length Ls of the substrate is The planar heating materials of Examples 1 to 12, which have a 3N constant load elongation rate of 2.5 times or more and a 3N constant load elongation rate of 20% or more, all have fast warming properties, surface conformability, bending durability, and sewing It was shown that the properties are excellent. Further, the planar heat generating materials of Examples 13, 14, and 15 in which the material of the metal wire (and the electrical resistivity of the conductive yarn) were changed, and the planar heat generating materials of Examples 16 and 17, in which the material of the base material was changed. Like the planar heat generating materials of Examples 1 to 12, the material was excellent in quick warming property, surface conformability, bending durability, and sewability.

On the other hand, while the 3N constant load elongation rate is 20% or more, the ratio (La / Ls) of the conductive yarn length La to the unit length Ls of the base material is less than 2.5 times. Although the planar heating material is excellent in surface followability, bending durability, and sewability, it takes 90 seconds or more to reach a measured temperature of 65°C, indicating that it is inferior in quick warming properties. rice field.

In addition, the ratio of the length La of the conductive thread to the unit length Ls of the base material (La/Ls) is 2.5 times or more, and the 3N constant load elongation rate is less than 20%. The exothermic material has excellent quick-warming properties, bending durability, and sewability, but when it is fixed along a trapezoidal box, it is confirmed that the fabric floats, indicating that it has poor surface conformability. .

The planar heat-generating material and the planar heat-generating element of the present invention are used, for example, in interior goods of vehicles such as steering wheel heaters and seat heaters, clothing such as outerwear, pants, and gloves, and health and medical products such as massage chairs and care beds. It can be used in appliances, chairs, furniture such as sofas, and the like.

REFERENCE SIGNS LIST 1 planar heating element 10 planar heating element 10a electrode installation area 20 electrode 100 conductive thread 110 metal wire 120 insulating resin 200 front substrate (substrate)
300 Back base material (base material)
400 Insulating yarn Ls Unit length of base material La Conductive yarn length R Conductive yarn diameter K1 Length of planar heating material when no load is applied K2 Length of planar heating material when load is applied F Load

Claims (9)

A planar heating material comprising a stretchable base material and a conductive thread,
The conductive thread is a metal wire coated with an insulating resin,
The length of the conductive thread is set to 2.5 times or more with respect to the unit length of the base material,
A planar heating material configured to have a constant load elongation of 20% or more when a load of 3N measured according to the elongation (D method) of JIS L1096 is applied. 2. The planar heating material according to claim 1, wherein the conductive thread is sewn onto the base material at intervals of 10 mm or less. 3. The planar heating material according to claim 2, wherein the conductive thread is sewn directly onto the base material. further comprising an insulating thread sewn directly onto the substrate;
3. The planar shape according to claim 2, wherein the conductive thread is passed through a gap between a seam of the insulating thread and the base material, so that the conductive thread is indirectly sewn to the base material. exothermic material. 5. The planar heating material according to claim 1, wherein the conductive thread has a diameter of 100 μm or less. The planar heat generating material according to any one of claims 1 to 5, wherein the base material is a base fabric composed of two or less layers of knitted fabric. The base material has a constant load elongation rate of 50% or more when a load of 3 N measured in accordance with the elongation rate (D method) of JIS L1096 is applied. The planar heating material described. The planar heating material according to any one of claims 1 to 7, wherein the conductive yarn has an electrical resistivity of 5 × 10 ^-5 Ω·m or less. A planar heating element comprising electrodes provided on the planar heating material according to any one of claims 1 to 8,
A planar heating element, wherein the conductive threads are processed so that the metal wires are exposed in the area where the electrodes are installed in the planar heating element.

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