JP7284082B2 - Heater manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a heater.

2. Description of the Related Art Conventionally, there has been known a heater provided with a conductive film as a heating element and a base material made of resin.

For example, Patent Literature 1 describes a flexible heater panel. This heater panel has a transparent substrate, a transparent conductive thin film, electrodes, and an adhesive layer. Polymer resins such as polyester resins are used as materials for transparent substrates. The transparent conductive thin film is _a metal thin film or a semiconductor thin film, and the material of the semiconductor thin film can be _In2O3 , _SnO2 , or ITO (Indium Tin Oxide). Electrodes are formed on both ends of the transparent conductive thin film. The electrodes are formed, for example, by printing a printable conductive ink. Conductive inks include, for example, silver particles in an epoxy resin binder. An adhesive layer completely covers the transparent conductive film and is used to adhere the heater panel to an object. As the adhesive forming the adhesive layer, it is preferable to use a transparent pressure-sensitive adhesive.

U.S. Pat. No. 4,952,783

According to the technique described in Patent Document 1, it is assumed that a pressure-sensitive adhesive is used as an adhesive layer that covers the transparent conductive thin film. However, it is difficult to say that this is advantageous from the viewpoint of manufacturing a highly reliable heater having a base material made of resin. Therefore, the technique described in Patent Document 1 has room for reexamination from the viewpoint of manufacturing a highly reliable heater.

Accordingly, the present invention provides a method for manufacturing a highly reliable heater having a base material made of resin.

The present invention
A method for manufacturing a heater,
A base material made of resin, a conductive film that is a heating element formed along the main surface of the base material, and a conductive film that is electrically connected to the conductive film and formed along the surface of the conductive film a covering step of supplying a curable composition having fluidity onto a sheet provided with a power feeding electrode to cover the conductive film and the power feeding electrode;
and a curing step of curing the curable composition,
The power supply electrode contains a conductive filler and a binder that binds the conductive filler,
A method for manufacturing a heater is provided.

According to the heater manufacturing method described above, it is possible to manufacture a highly reliable heater having a base material made of resin.

FIG. 1 is a plan view showing an example of a heater manufactured by a manufacturing method according to the present invention. FIG. 2 is a sectional view of the heater taken along line II-II of FIG. FIG. 3 is a diagram showing an example of a method for manufacturing a heater according to the present invention. FIG. 4 is a cross-sectional view showing an example of an article with a heater.

A flexible heater can be provided by using a base material made of resin in a heater provided with a conductive film. In this case, if a material containing a conductive filler and a binder is used as the power feeding electrode, durability of the heater can be easily improved. In addition, it is advantageous to increase the thickness of the power supply electrode in order to adjust the electrical resistance of the power supply electrode within a desired range while forming the power supply electrode in a limited space on the conductive film. The thickness of the power supply electrode is the dimension of the power supply electrode in the thickness direction of the conductive film.

On the other hand, according to the studies of the present inventors, when the thickness of the power supply electrode is large, using a pressure-sensitive adhesive as an adhesive layer covering the conductive film as in the technique described in Patent Document 1 is difficult for the heater. It was found that it is difficult to say that it is advantageous in terms of increasing the reliability of This is because it is difficult to form the pressure-sensitive adhesive layer along the step formed by the power supply electrode having a large thickness, and a gap is likely to be formed between the pressure-sensitive adhesive layer and the conductive film. is. Therefore, the present inventors have studied day and night about a technology that can appropriately cover the conductive film and the power supply electrode even when the power supply electrode is thick, and as a result of a great deal of trial and error, the heater according to the present invention has been proposed. I put it out.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the following description illustrates the present invention by way of example, and the present invention is not limited to the following embodiments.

As shown in FIGS. 1 and 2, the heater 1 includes a base material 10 made of resin, a conductive film 20 that is a heating element, an electrode 30 for power supply, and a protective layer 50 . As shown in FIG. 3, the method of manufacturing the heater 1 includes a coating process and a curing process. The sheet 1a includes a base material 10, a conductive film 20, and power feeding electrodes 30. As shown in FIG. The conductive film 20 is a heating element formed along the main surface of the base material 10 . The power supply electrode 30 is electrically connected to the conductive film 20 and formed along the surface of the conductive film 20 . As shown in FIG. 2, the power supply electrode 30 includes a conductive filler 30p and a binder 30m that binds the conductive filler 30p. In the coating step, a fluid curable composition 50 a is supplied onto the sheet 1 a to cover the conductive film 20 and the power feeding electrode 30 . In the curing step, the curable composition 50a is cured. In the coating step, since the curable composition 50 a has fluidity, gaps are less likely to be formed between the curable composition 50 a and the conductive film 20 and between the curable composition 50 a and the power supply electrode 30 . Curing of the curable composition 50a is performed in such a state, and the protective layer 50 is formed. Therefore, in the heater 1 , gaps are less likely to be formed between the protective layer 50 and the conductive film 20 and between the protective layer 50 and the power feeding electrode 30 . As a result, the conductive film 20 and the power supply electrode 30 are appropriately covered with the protective layer 50, and the heater 1 has high reliability.

The thickness of the power supply electrode 30 is not limited to a specific value. The thickness of the power supply electrode 30 is, for example, 50 μm or more. In this case, according to the manufacturing method described above, in the heater 1, the conductive film 20 and the feeding electrode 30 can be appropriately covered. In addition, the power supply electrode 30 tends to have a desired electrical resistance, and the heater 1 tends to exhibit desired heat generation performance.

The thickness of the power supply electrode 30 may be 60 μm or more, 70 μm or more, or 80 μm or more. The thickness of the power supply electrode 30 is, for example, 5 mm or less. This makes it easy to reduce the thickness of the protective layer 50 and thus the thickness of the heater 1 . The thickness of the power supply electrode 30 may be 1 mm or less, or may be 700 μm or less.

The viscosity of the curable composition 50a is not limited to a specific value as long as the curable composition 50a has the desired fluidity. The viscosity of the curable composition 50a at 25° C. is, for example, 950 pascal seconds or less. Thereby, even if the environmental temperature of the sheet 1a in the coating step is not high, the curable composition 50a tends to have desired fluidity. As a result, the conductive film 20 and the power supply electrode 30 are appropriately covered with the protective layer 50, and the heater 1 has high reliability.

The viscosity of the curable composition 50a at 25° C. is desirably 900 pascal seconds or less, more desirably 500 pascal seconds or less, and even more desirably 300 pascal seconds or less. The viscosity of the curable composition 50a at 25° C. is, for example, 0.1 pascal second or more, may be 0.5 pascal second or more, or may be 1 pascal second or more.

In the coating step, the method of supplying the fluid curable composition 50a onto the sheet 1a is not limited to a particular method. The method is, for example, a predetermined coating method such as die coating and comma coating.

As shown in FIG. 3, the curing process includes, for example, a first curing process and a second curing process. A second curing step is performed after the first curing step. The first curing step is a step of adjusting the curable composition 50a to a first cured state in which the fluidity has disappeared and the adhesiveness of the surface is maintained. The first curing step transforms the curable composition 50a into a partially cured product exhibiting a first cured state. By eliminating the fluidity of the curable composition 50a by the first curing step, the space occupied by the protective layer 50 can be adjusted to a desired state. Thereby, the conductive film 20 and the power feeding electrode 30 can be properly sealed. In addition, it is difficult for a gap to exist near the power feeding electrode 30 . Furthermore, the thickness of the protective layer 50 is less likely to vary, and the surface of the protective layer 50 tends to be flat. In the first cured state, the adhesiveness of the surface of the curable composition 50a is maintained, so that the adhesiveness can be used to adhere other members to the protective layer 50. FIG. The second curing step is a step of adjusting the curable composition 50a in the first cured state to a more cured state. The protective layer 50 is formed by the second curing step, and the adhesive strength between the protective layer 50 and other members tends to increase. In addition, the protective layer 50 tends to exhibit desired mechanical strength.

As shown in FIG. 3, the second curing step is performed, for example, while the protective film 60 is brought into contact with the surface of the curable composition 50a exhibiting the first cured state. Thereby, the protective film 60 can be arranged on the protective layer 50 . As a result, the protective film 60 can enhance the durability of the heater 1 .

Protective film 60 is not limited to a specific film. The protective film 60 may be a film that imparts predetermined optical properties to the heater 1 . The protective film 60 is, for example, a film with an antireflection film. The film with an antireflection film prevents reflection of light having a wavelength that should pass through the heater 1 . A film with an antireflection film includes, for example, a predetermined resin base material such as PET, and an antireflection coating formed on the base material. An antireflection coating is, for example, a stack of alternating layers of materials with different refractive indices. In this case, in the heater 1 , for example, the resin base material of the antireflection film-attached film is in contact with the protective layer 50 .

When the protective film 60 is brought into contact with the surface of the curable composition 50a exhibiting the first cured state, air bubbles may occur between the surface of the curable composition 50a and the protective film 60. In this case, after bringing the protective film 60 into contact with the surface of the curable composition 50a, a treatment for removing air bubbles may be performed. This treatment is performed, for example, by maintaining the environment of the laminate of the sheet 1a, the curable composition 50a, and the protective film 60 under predetermined conditions for a predetermined time. For example, in treatment for air bubble removal, the laminate can be placed in an environment of temperature from 25° C. to 100° C. and pressure from 1 to 5 atmospheres for 5 to 60 minutes. Thereby, air bubbles generated between the surface of the curable composition 50a and the protective film 60 can be removed. For example, an autoclave can be used to adjust the environment of the laminate to predetermined conditions.

A method for curing the curable composition 50a is not limited to a specific method. For example, in the curing step, the curable composition 50a is cured by irradiation with ultraviolet rays. This makes it easy to adjust the cured state of the curable composition 50a by adjusting the irradiation conditions of the ultraviolet rays. The curing of the curable composition 50a may be performed by adjusting the environmental conditions of the curable composition 50a so as to promote the thermosetting reaction. For example, the environmental temperature of the curable composition 50a may be adjusted to a temperature equal to or higher than the curing temperature of the curable composition 50a.

The curable composition 50a is not limited to a specific composition as long as it has fluidity and curable properties. The curable composition 50a is, for example, an ultraviolet curable resin composition containing ultraviolet curable monomers or oligomers such as epoxy acrylate, urethane acrylate, polyester acrylate, and silicone. In this case, the curable composition 50a can be cured in a short time. Also, the substrate 10 is not required to have high heat resistance. The curable composition 50a may be a thermosetting resin composition. Thermosetting resin compositions include, for example, monomers or oligomers such as silicones and epoxy resins. The cured product of the curable composition 50 a is desirably transparent to the light of the wavelength that should pass through the heater 1 . In this specification, being transparent to the light of the wavelength to be transmitted through the heater 1 means that the transmittance of the light of that wavelength is 60% or more. The curable composition 50a is desirably an optically clear resin (OCR) composition.

As shown in FIG. 3, in the first curing step, for example, ultraviolet rays are irradiated from the ultraviolet lamp 5a toward the curable composition 50a with the surface of the curable composition 50a exposed. In this case, the curing reaction of the curable composition 50a proceeds easily inside the curable composition 50a, and the curing reaction of the curable composition 50a does not proceed easily on the surface of the curable composition 50a. This is because the presence of oxygen on the surface of the curable composition 50a suppresses the curing reaction of the curable composition 50a. In the first curing step, the ultraviolet irradiation conditions are adjusted so that the curable composition 50a exhibits the first cured state.

As shown in FIG. 3 , in the second curing step, for example, ultraviolet rays are irradiated from the ultraviolet lamp 5 b toward the protective film 60 while the surface of the curable composition 50 a is in contact with the protective film 60 . In this case, the protective film 60 typically transmits ultraviolet rays emitted from the ultraviolet lamp 5b. Since the surface of the curable composition 50a is in contact with the protective film 60, oxygen is less likely to exist in the vicinity of the surface of the curable composition 50a, and the curing reaction of the curable composition 50a also occurs on the surface of the curable composition 50a. is easy to advance. As a result, the protective layer 50 can be properly formed.

The substrate 10 has transparency to light of a predetermined wavelength such as visible light or near-infrared light, for example. The thickness of base material 10 is not limited to a specific thickness. The thickness of the substrate 10 is, for example, 10 to 200 μm from the viewpoint of transparency, strength, and ease of handling. The thickness of the base material 10 may be 20-180 μm, or may be 30-160 μm.

The material of the base material 10 is not limited to a specific resin. The resin contained in the base material 10 is, for example, at least one selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polyimide, polycarbonate, polyetheretherketone, and aromatic polyamide.

The main surface of the substrate 10 may be covered with an intermediate layer, for example. The intermediate layer contains, for example, an organic polymer forming a cured product and inorganic particles dispersed in the cured product. In this case, the adhesion of the conductive film 20 to the base material 10 tends to be high.

As long as the conductive film 20 functions as a heating element in the heater 1, the material of the conductive film 20 is not limited to a specific material. The conductive film 20 contains, for example, at least one of a metal and a metal compound. This makes it easier for the heater 1 to exhibit a desired output.

The metal contained in the conductive film 20 is not limited to a specific metal. The metal contained in the conductive film 20 is, for example, at least one selected from the group consisting of copper, nickel, chromium, palladium, lead, platinum, gold, and silver. The metal compound contained in the conductive film 20 is not limited to a specific metal compound. The metal compound contained in the conductive film 20 is, for example, metal oxide or metal nitride.

The conductive film 20 is transparent to light having a predetermined wavelength λ _p of 910 nm or longer, for example. In this case, the heater 1 can be applied to devices or systems that use light of wavelength λ _p for communication, sensing, or the like.

The conductive film 20 desirably contains indium oxide. In this case, the specific resistance of the conductive film 20 tends to be low. The conductive film 20 may contain indium oxide as a main component. In addition, in this specification, the "main component" means the component contained in the largest amount on a mass basis.

The conductive film 20 may contain polycrystals. This is advantageous for providing the conductive film 20 with desired properties. For example, if the conductive film 20 is polycrystalline, the specific resistance of the conductive film 20 tends to be low.

Conductive film 20 preferably comprises indium tin oxide (ITO). In this case, the content of tin oxide in ITO is, for example, 4 to 14% by weight, preferably 5 to 13% by weight. The ITO contained in the conductive film 20 desirably has a polycrystalline structure. This is advantageous from the viewpoint of keeping the resistivity of the conductive film 20 low.

Conductive film 20 may be a single layer film or a multilayer film such as an IAI film with a layer of silver disposed between two layers of indium zinc oxide (IZO).

The thickness of the conductive film 20 is not limited to a specific thickness. Typically, the thickness of the conductive film 20 is smaller than the thickness of the feeding electrode 30 . The thickness of the conductive film 20 is, for example, 20-200 nm. In this case, the heater 1 can exhibit good temperature rising performance, and cracks occurring in the conductive film 20 can be suppressed. The thickness of the conductive film 20 is preferably 25-190 nm, more preferably 30-180 nm.

As shown in FIGS. 1 and 2, the heater 1 has, for example, a pair of power supply electrodes 30 . The pair of power supply electrodes 30 extends parallel to each other in the longitudinal direction, for example. The pair of power supply electrodes 30 are arranged, for example, on both ends of the conductive film 20 in the direction perpendicular to the longitudinal direction along the surface of the conductive film 20 . For example, a predetermined voltage is applied to the pair of power supply electrodes 30 and the conductive film 20 generates heat.

Since the base material 10 is made of resin, the dimensions of the base material 10 are likely to change when the heater 1 is exposed to a high-temperature and high-humidity environment. On the other hand, since the power supply electrode 30 contains the conductive filler 30p and the binder 30m, the stress generated in the conductive film 20 tends to be small despite the dimensional change of the base material 10 in a high-temperature and high-humidity environment. . Therefore, cracks are less likely to occur in the conductive film 20 . In addition, since the power supply electrode 30 contains the conductive filler 30p and the binder 30m, even if the heater 1 is exposed to a high-temperature and high-humidity environment, the power supply electrode 30 and the portion in contact with the power supply electrode 30 It is easy to maintain high adhesion. As a result, even if the heater 1 is exposed to a high-temperature and high-humidity environment, the performance of the heater 1 is less likely to deteriorate. A portion in contact with the power feeding electrode 30 is, for example, the conductive film 20 .

The specific resistance of the power supply electrode 30 is not limited to a specific value. The specific resistance of the power supply electrode 30 is, for example, 100 μΩ·cm or less. Thereby, heat generation in the power supply electrode 30 can be suppressed, and the conductive film 20 can be heated in a desired state.

The specific resistance of the power feeding electrode 30 is preferably 80 μΩ·cm or less, more preferably 70 μΩ·cm or less, even more preferably 60 μΩ·cm or less, and most preferably 50 μΩ·cm or less.

Binder 30m typically contains a resin. The resin contained in the binder 30m is not limited to a specific resin. The binder 30m contains polyester resin, for example. Thereby, the heater 1 tends to exhibit high durability even when exposed to a high-temperature and high-humidity environment. The polyester resin desirably contains an aromatic polyester.

A material of the conductive filler 30p is not limited to a specific material. Conductive filler 30p typically includes a metal or metal compound. Conductive filler 30p desirably includes silver or a silver compound. A predetermined coating may be applied to the conductive filler 30p. For example, the conductive filler 30p may be coated to enhance affinity with the binder 30m.

The size of the conductive filler 30p is not limited to a specific value. The average particle size of the conductive filler 30p is, for example, 0.01 μm or more, may be 0.1 μm or more, or may be 0.5 μm or more. The average particle size of the conductive filler 30p is, for example, 10 μm or less, may be 5 μm or less, or may be 2 μm or less. The average particle size of the conductive filler 30p can be determined, for example, by the following method. For example, a flaky sample prepared from the power supply electrode 30 is observed with a transmission electron microscope, the maximum diameter of each of 50 or more conductive fillers 30p is obtained, and the arithmetic average value of the maximum diameter is calculated as the conductivity. Determined as the average particle size of the filler 30p.

The shape of the conductive filler 30p is not limited to a specific shape. The shape of the conductive filler 30p may be spherical, fibrous, or flaky. The conductive filler 30p may be amorphous.

The content of the conductive filler 30p in the power supply electrode 30 is not limited to a specific value. The content of the conductive filler 30p in the power supply electrode 30 is, for example, 60% by weight to 95% by weight.

An example of a method for creating the sheet 1a will be described. The conductive film 20 is formed by sputtering, for example. The conductive film 20 is desirably obtained by performing sputtering using a predetermined target material to form a thin film derived from the target material on the main surface of the substrate 10 . More desirably, a thin film derived from the target material is formed on the main surface of the substrate 10 by high magnetic field DC magnetron sputtering. In this case, the conductive film 20 can be formed at a low temperature. Therefore, for example, the conductive film 20 can be formed on the main surface of the base material 10 even if the heat resistant temperature of the base material 10 is not high. In addition, defects are less likely to occur in the conductive film 20, and the internal stress of the conductive film 20 tends to be low. Also, by adjusting the sputtering conditions, it is easy to form a thin film that is desirable as the conductive film 20 . When the conductive film 20 is a multilayer film, the conductive film 20 can be formed by, for example, using different types of target materials and performing sputtering under conditions suitable for each target material. Moreover, when the main surface of the base material 10 is covered with the said intermediate layer, the electrically conductive film 20 is formed on the intermediate layer, for example.

The thin film formed on the main surface of the base material 10 is annealed if necessary. For example, the thin film is placed in the air at 120° C. to 150° C. for 1 hour to 3 hours for annealing. As a result, crystallization of the thin film is promoted, and the polycrystalline conductive film 20 is advantageously formed. If the temperature of the environment of the thin film during annealing and the annealing time are within the above ranges, the heat resistant temperature of the base material 10 does not have to be high, and a resin can be used as the material of the base material 10 . In addition, defects are less likely to occur in the conductive film 20, and the internal stress of the conductive film 20 tends to be low. By adjusting the conditions of the annealing treatment, it is easy to obtain the desired conductive film 20 from the viewpoint of specific resistance.

The conductive film 20 may be formed by a method such as vacuum deposition or ion plating instead of sputtering.

A method for forming the power supply electrode 30 is not limited to a specific method. For example, a predetermined pattern of a composition containing raw materials of the conductive filler 30p and the binder 30m is formed on the conductive film 20 by a method such as coating with a dispenser or screen printing. If necessary, the pattern of the composition is subjected to a treatment such as heating to cure the composition. Thus, the power supply electrode 30 can be formed, and the sheet 1a is obtained.

The heater 1 further includes an adhesive layer 40 as shown in FIG. In the heater 1 , the base material 10 is positioned between the conductive film 20 and the adhesive layer 40 in the thickness direction of the base material 10 . As a result, the heater 1 can be attached to the article by pressing the adhesive layer 40 against the article. As shown in FIG. 3, the method of manufacturing the heater 1 may further include the step of forming an adhesive layer 40 on the sheet 1a.

The adhesive layer 40 typically contains an adhesive. The adhesive layer 40 may be formed of a single layer, or may be formed as a laminate of multiple layers. When the adhesive layer 40 is a laminate of a plurality of layers, for example, the adhesive layer 40 may have a structure in which adhesive layers are formed on both sides of a predetermined base material. The adhesive contained in the adhesive layer 40 may be a known adhesive such as an acrylic adhesive, a rubber adhesive, or a silicone adhesive.

For example, the heater 1 can be used to provide a heater-equipped article 100 shown in FIG. As shown in FIG. 4, the heater-equipped article 100 includes an article 70 and a heater 1 . Article 70 has an adherend surface 71 . The article 70 is made of, for example, metal material, ceramic material, glass, or resin. The adhesive layer 40 is in contact with the adherend surface 71 .

Also, the adhesive layer 40 may be covered with a separator (not shown). In this case, when the heater 1 is attached to the article 70, the separator is peeled off and the adhesive layer 40 is exposed. The separator is, for example, a polyester resin film such as polyethylene terephthalate (PET).

The heater 1 is arranged on the optical path of the light of wavelength _λp in, for example, a device or system that performs processing using light of wavelength _λp . This device or system uses, for example, light of wavelength λ _p to perform predetermined processing such as sensing or communication. Article 70, for example, constitutes the housing of such a device.

The present invention will be described in more detail below with reference to examples. In addition, the present invention is not limited to the following examples. First, a method for evaluating samples according to each example and comparative example will be described.

[Resin species analysis method]
The type of resin contained in the conductive paste used to prepare the sheet according to each example was identified by the following method. First, chloroform was added to a predetermined amount of conductive paste, and ultracentrifugation was performed. As a result, chloroform-soluble components and chloroform-insoluble components were separated. The resulting chloroform soluble components were dried with a nitrogen purge. Next, methanol was added to the dried chloroform-soluble components to separate the methanol-soluble components from the methanol-insoluble components. After that, the methanol-insoluble component in the dried chloroform-soluble component was dried by nitrogen purge to obtain a dried product. This dried product was used as a sample for Fourier transform infrared spectroscopy (FT-IR), and measurement results were obtained. This measurement was performed under the following conditions.
Analyzer: Fisher Scientific Fourier Transform Infrared Spectrometer Nicolet iS10 FT-IR
Measurement method: Single reflection total reflection (ATR) method (Diamond 45°, SmartiTR)
Resolution: 4 cm ^-1
Detector: DTGS detector Accumulation times: 64 times

<Example 1>
Using indium tin oxide (ITO) (content of tin oxide: 10% by weight) as a target material on one main surface of a polyethylene naphthalate (PEN) film having a thickness of 125 μm, the surface of the target material An ITO film was formed on a PEN film by a DC magnetron sputtering method in a high magnetic field with a magnetic flux density of 80 to 150 mT (millitesla) in a horizontal magnetic field at 100 mT (millitesla) and in the presence of an inert gas. The PEN film on which the ITO film was formed was placed in the air at 150° C. for 3 hours for annealing treatment. This crystallized the ITO to form a transparent conductive film.

The thickness of the transparent conductive film was measured by an X-ray reflectance method using an X-ray diffractometer (manufactured by Rigaku, product name: RINT2200). As a result, the thickness of the transparent conductive film was 50 nm. Also, an X-ray diffraction pattern for the transparent conductive film was obtained using an X-ray diffractometer. CuKα rays were used as X-rays. The obtained X-ray diffraction pattern confirmed that the transparent conductive film (heating element) had a polycrystalline structure.

Next, the PEN film on which the transparent conductive film was formed was cut into strips. A conductive paste DW117 manufactured by Toyobo Co., Ltd. was applied onto the transparent conductive film with a dispenser to form a pair of strip-shaped conductive paste patterns extending parallel to each other. Next, the conductive paste pattern was heated in an environment of 150° C. for 240 minutes to cure the conductive paste, thereby forming a pair of power supply electrodes. Thus, a sheet according to Example 1 was produced. The distance between the pair of power supply electrodes was 20 mm. The width of the power supply electrode was about 1 mm, and the thickness of the power supply electrode was 120 μm. The conductive paste DW117 contained silver as a conductive filler, and the content of the conductive filler in the conductive paste was 89% by weight. In addition, according to the results of FT-IR measurement, the conductive paste DW117 contained a polyester resin containing an aromatic polyester as a binder.

An ultraviolet curable optically transparent resin composition HSVR330 manufactured by Dexerials was applied onto the sheet of Example 1 by die coating to form a coating film of the ultraviolet curable optically transparent resin composition. This coating film covered the transparent conductive film and the pair of power supply electrodes. The viscosity at 25° C. of the ultraviolet curable optically transparent resin composition HSVR330 was 5.3 pascal seconds. After that, using a UV irradiation device (main wavelength: 365 nm), the coating film of the UV-curable optically transparent resin composition immediately after being supplied onto the sheet according to Example 1 was irradiated with UV rays. The UV irradiation conditions were adjusted to 1000 mJ/cm ² . As a result, the ultraviolet curable optically transparent resin composition was semi-cured as a whole and lost its fluidity. On the other hand, the surface of the coating film of the ultraviolet curable optically transparent resin composition was not cured and maintained adhesiveness. Next, a film MUAR7 with an antireflection film manufactured by Panasonic Corporation was brought into contact with the surface of the coating film of the ultraviolet-curable optically transparent resin composition to obtain a laminate. After that, the laminate was placed in an autoclave adjusted to the conditions of 50° C. and 5 atm for 15 minutes, and air bubbles between the surface of the coating film of the UV-curable optically transparent resin composition and the film with an antireflection film were removed. removed. The film with an antireflection film was a film in which an antireflection coating was applied on a PET substrate. Next, the antireflection film-attached film was irradiated with ultraviolet rays using a UV irradiation device (main wavelength: 200 to 450 nm). The UV irradiation conditions were adjusted to 3000 mJ/cm ² . As a result, the surface of the ultraviolet-curable optically transparent resin composition was cured, and the entire ultraviolet-curable optically transparent resin composition was cured. As a result, a heater according to Example 1 was obtained, in which a protective layer having a thickness of about 200 μm was formed from the cured product of the ultraviolet curable optically transparent resin composition.

<Example 2>
A sheet according to Example 2 was produced in the same manner as in Example 1, except that conductive paste DW351 manufactured by Toyobo Co., Ltd. was used instead of conductive paste DW117. The distance between the pair of power supply electrodes was 20 mm. The width of the power supply electrode was about 1 mm, and the thickness of the power supply electrode was 120 μm. The conductive paste DW351 contained silver as a conductive filler, and the content of the conductive filler in the conductive paste was 86% by weight. In addition, according to the results of FT-IR measurement, the conductive paste DW351 contained a polyester resin containing an aromatic polyester as a binder. A heater according to Example 2 was manufactured in the same manner as in Example 1, except that the sheet according to Example 2 was used instead of the sheet according to Example 1.

<Example 3>
Equal amounts of liquid A and liquid B of thermosetting optically transparent resin composition KER-2500 manufactured by Shin-Etsu Chemical Co., Ltd. were mixed, defoamed, and supplied onto the sheet according to Example 1 by die coating. A coating film of a thermosetting optically transparent resin composition was formed. This coating film covered the transparent conductive film and the pair of power feeding electrodes. The viscosity at 25° C. of the thermosetting optically transparent resin composition obtained by mixing equal amounts of KER-2500 A and B liquids and defoaming the mixture was about 4 to 5 pascal seconds. Next, a film MUAR7 with an antireflection film manufactured by Panasonic Corporation was brought into contact with the surface of the coating film of the thermosetting optically transparent resin composition to obtain a laminate. After that, the laminate was placed in an environment of 100° C. for 1 hour, and then placed in an environment of 120° C. for 1 hour. As a result, the entire thermosetting optically transparent resin composition was cured. As a result, a heater according to Example 3 was obtained in which a protective layer having a thickness of about 200 μm was formed from the cured product of the thermosetting optically transparent resin composition.

<Comparative Example 1>
An optical transparent adhesive sheet CS9864UA manufactured by Nitto Denko Corporation was adhered onto the sheet according to Example 1, and the transparent conductive film and the pair of feeding electrodes were covered with the optical transparent adhesive sheet. An antireflection film-attached film MUAR7 manufactured by Panasonic Corporation was placed on the optical transparent pressure-sensitive adhesive sheet. Thus, a heater according to Comparative Example 1 was produced.

<Comparative Example 2>
A heater according to Comparative Example 2 was produced in the same manner as in Comparative Example 1, except that the sheet according to Example 2 was used instead of the sheet according to Example 1.

Using an optical microscope, the cross sections of the heaters according to each example and each comparative example were observed. In the cross section of the heater according to each example, no gap was observed between the protective layer and the transparent conductive film and between the protective layer and the power feeding electrode. Therefore, it was suggested that the heater according to each example has high reliability. On the other hand, in the cross section of the heater according to each comparative example, a gap was confirmed between the optical transparent pressure-sensitive adhesive sheet and the transparent conductive film or between the optical transparent pressure-sensitive adhesive sheet and the power feeding electrode.

Reference Signs List 1 heater 1a sheet 10 substrate 20 conductive film (heating element)
30 power supply electrode 30p conductive filler 30m binder 50a curable composition 60 protective film

Claims (6)

A method for manufacturing a heater,
A base material made of resin, a conductive film that is a heating element formed along the main surface of the base material, and a conductive film that is electrically connected to the conductive film and formed along the surface of the conductive film a covering step of supplying a curable composition having fluidity onto a sheet provided with a power feeding electrode to cover the conductive film and the power feeding electrode;
and a curing step of curing the curable composition,
The power supply electrode contains a conductive filler and a binder that binds the conductive filler,
A method for manufacturing a heater. 2. The method of manufacturing a heater according to claim 1, wherein the power supply electrode has a thickness of 50 [mu]m or more. 3. The method for manufacturing a heater according to claim 1, wherein the curable composition has a viscosity at 25[deg.] C. of 950 pascal seconds or less. The curing step includes a first curing step and a second curing step performed after the first curing step,
The first curing step is a step of adjusting the curable composition to a first cured state in which fluidity is lost and surface adhesion is maintained,
The second curing step is a step of adjusting the curable composition in the first cured state to a more cured state.
A method for manufacturing a heater according to any one of claims 1 to 3. 5. The method of manufacturing a heater according to claim 4, wherein the second curing step is performed while a protective film is in contact with the surface of the curable composition. The method for manufacturing a heater according to any one of claims 1 to 5, wherein the curable composition is cured by irradiation with ultraviolet rays.

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