JP2020021662A - heater - Google Patents

Abstract

To provide a heater in which a heating element formed on a sheet-like support made of an organic polymer has high resistance to rubbing or bending.SOLUTION: A heater (1a) according to the present disclosure includes a sheet-shaped support (10) made of an organic polymer, a heating element (20), and a pair of power supply electrodes (30) in contact with the heating element (20). The heating element (20) is a transparent conductive film made of a polycrystal containing indium oxide as a main component. In the heater (1a), the heating element (20) has a specific resistance of 1.4×10Ωcm to 3×10Ωcm. The thickness of the heating element (20) is more than 20 nm and 100 nm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heater.

  Conventionally, a planar heater provided with a thin-film heating element containing indium tin oxide (ITO) has been known.

  For example, Patent Document 1 describes a heat glass including a thin-film ITO heating element formed by sintering a paste containing indium tin oxide (ITO) as a main component on a glass substrate. The ITO heating element is formed by screen-printing and sintering an ITO paste made by mixing ITO spherical particles having a predetermined average particle diameter with a solvent and a resin on a glass substrate. For example, the ITO paste is sintered at 480 ° C. for 30 minutes. It is described that an ITO heating element having a low resistivity and a high transmittance is thereby formed.

  Patent Document 2 proposes a transparent planar heater having a configuration in which a laminated thin film of indium oxide / Ag / indium oxide is formed on a transparent organic polymer film such as polyethylene terephthalate (PET) by a DC magnetron sputtering method. .

JP 2016-46237 A JP-A-6-283260

  According to Patent Literature 1, an ITO heating element formed by sintering an ITO paste has a low resistivity of 0.0001 Ωcm to 20 Ωcm, and has a high transmittance at a wavelength of 400 to 1500 nm. On the other hand, in the technique described in Patent Document 1, a glass substrate or the like is necessary to withstand sintering of the ITO paste. For this reason, in the technology described in Patent Document 1, it is not assumed that a heating element that is a transparent conductive film such as ITO is formed on a sheet-shaped support made of an organic polymer. Roll-to-roll manufacturing is not applicable to heat glass. In addition, it is difficult to install or attach the heat glass described in Patent Literature 1 to a location having a curved surface shape.

  According to the transparent planar heater disclosed in Patent Document 2, since an organic polymer film is used as a substrate, roll-to-roll manufacturing can be applied. In addition, it is considered that the transparent sheet heater of Patent Document 2 can be easily installed or attached to a location having a curved surface shape. However, in general, a laminate including an Ag thin film is likely to be susceptible to corrosion in the Ag thin film due to rubbing and scratching of the thin film, and it is considered that handling during manufacturing and construction is difficult. Patent Document 2 also proposes a transparent sheet heater having a configuration in which ITO is formed on a transparent organic polymer film such as polyethylene terephthalate (PET) by a DC magnetron sputtering method. According to this transparent sheet heater, although corrosion due to scratching of the thin film can be prevented, since the resistivity of ITO is high, the ITO film has a very thick thickness of 400 nm. For this reason, there is a possibility that the ITO film may be easily cracked by bending deformation of the film at the time of manufacturing or construction.

  As described above, according to Patent Literature 1, it is possible to form a low-resistivity and highly-transparent ITO heating element by sintering an ITO paste on a glass substrate. A glass substrate or the like is required, and a heating element which is a transparent conductive film such as ITO cannot be formed on a film-like support made of an organic polymer. On the other hand, in Patent Document 2, a transparent organic polymer film is used as a substrate, and a transparent film in which an indium oxide / Ag / indium oxide thin film laminate or an ITO thin film having a thickness of 400 nm is formed by a DC magnetron sputtering method. Planar heaters have been proposed. However, according to the technique described in Patent Literature 2, corrosion due to scratches during manufacturing or construction or cracks due to bending may easily occur.

  Accordingly, the present invention provides a heater in which a heating element formed on a sheet-like support made of an organic polymer has high resistance to rubbing or bending.

The present invention
A sheet-like support made of an organic polymer,
A heating element that is a transparent conductive film made of a polycrystal containing indium oxide as a main component,
And at least a pair of power supply electrodes in contact with the heating element,
The heating element has a specific resistance of ^{1.4 × 10 -4 Ω · cm~3 ×} 10 -4 Ω · cm,
The thickness of the heating element is more than 20 nm and 100 nm or less;
Provide a heater.

  In the above heater, the heating element is formed on a sheet-like support made of an organic polymer, but the heating element has high resistance to rubbing or bending during manufacturing or construction.

FIG. 1 is a sectional view showing an example of the heater of the present invention. FIG. 2 is a sectional view showing another example of the heater of the present invention. FIG. 3 is a sectional view showing still another example of the heater of the present invention. FIG. 4 is a sectional view showing a modification of the heater shown in FIG. FIG. 5 is a sectional view showing still another example of the heater of the present invention. FIG. 6 is a sectional view showing still another example of the heater of the present invention. FIG. 7 is a diagram conceptually illustrating a method for measuring the internal stress of the transparent conductive film.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description exemplifies the present invention, and the present invention is not limited to the following embodiments.

As shown in FIG. 1, the heater 1a includes a support 10, a heating element 20, and at least a pair of power supply electrodes 30. The support 10 is made of an organic polymer and has a sheet shape. The heating element 20 is a transparent conductive film made of a polycrystal containing indium oxide as a main component. In the present specification, the “main component” means a component that is contained most on a mass basis. At least one pair of power supply electrodes 30 is in contact with the heating element 20. The heating element 20 has a specific resistance of ^{1.4 × 10 -4 Ω · cm~3 ×} 10 -4 Ω · cm. The thickness of the heating element 20 is more than 20 nm and 100 nm or less. The heater 1a is typically a planar heater.

The heating element 20 is in contact with the sheet-like support 10 made of an organic polymer, and the thickness of the heating element 20 is thinner than 20 nm and 100 nm or less. Cracks are less likely to occur. Further, since the specific resistance of the heating element 20 is as low as 1.4 × 10 ⁻⁴ Ω · cm to 3 × 10 ⁻⁴ Ω · cm, even if the thickness of the heating element 20 is so thin, the sheet of the heating element 20 may be used. The resistance is low, and the heater 1a can exhibit desired heat generation performance.

The specific resistance of the heating element 20 is preferably a ^{1.4 × 10 -4 Ω · cm~2.7 ×} 10 -4 Ω · cm, more preferably 1.4 × 10 ^-4 Ω · cm~2. 5 × 10 ⁻⁴ Ω · cm.

The carrier density of the heating element 20 is, for example, 6 × 10 ²⁰ cm ^{−3 to} 16 × 10 ²⁰ cm ⁻³ . Thus, the heating element 20 more easily has a low specific resistance, and the heating element 20 has a low sheet resistance even if the thickness of the heating element 20 is thin. The carrier density of the heating element 20 is determined by the Hall effect measurement, and the Hall effect measurement is performed according to, for example, the van der Pauw method. The carrier density of the heating element 20 is preferably 7 × 10 ²⁰ cm ^{−3 to} 16 × 10 ²⁰ cm ⁻³ , and more preferably 8 × 10 ²⁰ cm ^{−3 to} 16 × 10 ²⁰ cm ⁻³ .

  For example, the ratio of the number of tin atoms to the sum of the number of indium atoms and the number of tin atoms in the heating element 20 is 0.04 to 0.15. Thus, the heating element 20 more easily has a low specific resistance, and the heating element 20 has a low sheet resistance even if the thickness of the heating element 20 is thin.

  For example, the crystal grains of the heating element 20 have an average size of 150 nm to 500 nm, assuming that the diameter of a perfect circle having an area equal to the projected area of each crystal grain in a specific direction is the size of each crystal grain. Thus, the heating element 20 more easily has a low specific resistance, and the heating element 20 has a low sheet resistance even if the thickness of the heating element 20 is thin. The crystal grains of the heating element 20 preferably have an average size of 180 nm to 500 nm, and more preferably have an average size of 200 nm to 500 nm. The crystal grains of the heating element 20 can be determined, for example, according to the method described in the embodiment.

  The concentration of the argon atoms contained in the heating element 20 is, for example, 3.5 ppm (parts per million) or less on a mass basis. Thus, the heating element 20 more easily has a low specific resistance, and the heating element 20 has a low sheet resistance even if the thickness of the heating element 20 is thin. The concentration of the argon atoms contained in the heating element 20 is desirably 3.0 ppm or less on a mass basis, and more desirably 2.7 ppm or less on a mass basis.

  The internal stress of the heating element 20 measured by the X-ray stress measurement method is, for example, 20 to 650 MPa. Thereby, cracks are less likely to occur in the heating element 20. The internal stress of the heating element 20 can be measured by the method described in the embodiment according to the X-ray stress measurement method. The internal stress of the heating element 20 may be 50 to 650 MPa, or may be 100 to 650 MPa.

  The transparent conductive film forming the heating element 20 is not particularly limited. For example, sputtering is performed using a target material containing indium oxide as a main component, and one of the main surfaces of the support 10 is derived from the target material. It is obtained by forming a thin film. Desirably, a thin film derived from the target material is formed on one main surface of the support 10 by a high magnetic field DC magnetron sputtering method. In this case, the heating element 20 can be formed at a lower temperature than when the ITO paste is screen-printed on a glass substrate and sintered. Therefore, the heating element 20 can be formed on the sheet-like support 10 made of an organic polymer. In addition, defects are less likely to occur in the transparent conductive film, more carriers can be generated, and the internal stress of the heating element 20 tends to be lower.

  The thin film formed on one main surface of the support 10 is annealed, if necessary. For example, the annealing treatment is performed by placing the thin film in air at 120 ° C. to 150 ° C. for 1 hour to 3 hours. Thereby, crystallization of the thin film is promoted, and a transparent conductive film made of polycrystal is advantageously formed. If the temperature of the environment of the thin film at the time of the annealing process and the time of the annealing process are in the above ranges, a sheet-like support made of an organic polymer can be used for the support 10 of the heating element 20 without any problem. In addition, defects are unlikely to occur in the transparent conductive film, and the internal stress of the heating element 20 tends to be low.

  In the heater 1a, the material of the support 10 is not particularly limited, but preferably, the support 10 is selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polyimide, polycarbonate, polyolefin, polyetheretherketone, and aromatic polyamide. Is made of at least one. Thereby, the heater 1a has transparency and is easily bent.

  The thickness of the support 10 is not limited to a specific thickness, but is, for example, 10 μm to 200 μm from the viewpoint of good transparency, good strength, and easy handling. The thickness of the support 10 may be 20 to 180 μm, or 30 to 160 μm.

  The support 10 may include a functional layer such as a hard coat layer, a stress relaxation layer, or an optical adjustment layer. These functional layers form, for example, one main surface of the support 10 that comes into contact with the heating element 20. These functional layers can be the base of the heating element 20.

  As shown in FIG. 1, the pair of power supply electrodes 30 are formed, for example, in contact with the second main surface 22 of the heating element 20. The second main surface 22 is a main surface on the opposite side of the first main surface 21 of the heating element 20 in contact with the support 10. The power supply electrode 30 has a thickness of, for example, 1 μm or more. In this case, the current capacity of the power supply electrode 30 is easily adjusted to a value suitable for operating the heater 1a at a high temperature rising rate. Thus, when the heater 1a is operated at a high temperature rising rate, the power supply electrode 30 is not easily broken. The thickness of the power supply electrode 30 is much larger than the thickness of an electrode formed on a transparent conductive film used for a display device such as a touch panel. The thickness of the power supply electrode 30 is desirably 1.5 μm or more, and more desirably 2 μm or more. The thickness of the power supply electrode 30 is, for example, 5 mm or less, may be 1 mm or less, or may be 700 μm or less.

  The pair of power supply electrodes 30 is not particularly limited as long as it can supply power from a power supply (not shown) to the heating element 20, and is made of, for example, a metal material. A masking film is arranged so as to cover a part of the second main surface 22 of the heating element 20. When another film is laminated on the second main surface 22 of the heating element 20, a masking film may be arranged on the film. In this state, a metal film of 1 μm or more is formed on the exposed portion of the heating element 20 and the masking film by a dry process such as chemical vapor deposition (CVD) and physical vapor deposition (PVD) or a wet process such as plating. To form Thereafter, by removing the masking film, the metal film remains on the exposed portion of the heating element 20, and a pair of power supply electrodes 30 can be formed. Further, a metal film of 1 μm or more is formed on the second main surface 22 of the heating element 20 by a dry process such as CVD and PVD or a wet process such as a plating method, and thereafter, unnecessary metal films are removed by etching. Alternatively, a pair of power supply electrodes 30 may be formed.

  The pair of power supply electrodes 30 may be formed of a conductive paste. In this case, a pair of power supply electrodes 30 can be formed by applying a conductive paste to the heating element 20 that is a transparent conductive film by a method such as screen printing.

  The heater 1a is disposed on the optical path of the near-infrared ray in an apparatus that performs processing using near-infrared rays included in a wavelength range of 780 to 1500 nm, for example. This device performs a predetermined process such as sensing or communication using near infrared rays included in a wavelength range of 780 to 1500 nm, for example. For this reason, the heater 1a has high transmissivity with respect to, for example, near infrared rays included in the wavelength range of 780 to 1500 nm.

(Modification)
The heater 1a can be changed from various viewpoints. For example, the heater 1a may be changed to the heaters 1b to 1f shown in FIGS. The heaters 1b to 1f have the same configuration as that of the heater 1a, unless otherwise specified. Components of the heaters 1b to 1f that are the same as or correspond to the components of the heater 1a are denoted by the same reference numerals, and detailed description thereof will be omitted. The description of the heater 1a also applies to the heaters 1b to 1f unless technically contradictory.

  As shown in FIG. 2, the heater 1b further includes a low refractive index layer 40. The low-refractive-index layer 40 may be in contact with the second main surface 22 of the heating element 20 or may be arranged apart from the second main surface 22.

  As shown in FIG. 3, the heater 1c further includes a protective film 42 and a first adhesive layer 45. The protection film 42 is arranged at a position closer to the second main surface 22 than the first main surface 21 of the heating element 20. The first adhesive layer 45 is in contact with the protection film 42 and the heating element 20 between the protection film 42 and the heating element 20. The protective film 42 is the outermost layer at a position closer to the second main surface 22 than the first main surface 21 of the heating element 20, and corresponds to the low refractive index layer 40. Thus, the protective film 42 is attached to the second main surface 22 of the heating element 20 via the first adhesive layer 45. As described above, since the heating element 20 is made of a polycrystal containing indium oxide as a main component, its toughness is generally low. Therefore, by protecting the heating element 20 with the protective film 42, the impact resistance of the heater 1c can be improved.

  The material of the protective film 42 is not particularly limited, but is made of a predetermined synthetic resin. The thickness of the protective film 42 is not particularly limited, but is, for example, 20 μm to 200 μm. Thus, it is possible to prevent the heater 1c from having an excessively large thickness while having good impact resistance.

  The first adhesive layer 45 is not particularly limited, but is formed of, for example, a known optical adhesive such as an acrylic adhesive.

  The heater 1d is a further modified version of the heater 1c, and has the same configuration as that of the heater 1c, except where otherwise described. As shown in FIG. 4, the heater 1d further includes a protective film 42 and a first adhesive layer 45. The protection film 42 is arranged at a position closer to the second main surface 22 than the first main surface 21 of the heating element 20. The first adhesive layer 45 is in contact with the protection film 42 and the heating element 20 between the protection film 42 and the heating element 20. As shown in FIG. 4, the heater 1 d also has the low refractive index layer 40, but the low refractive index layer 40 has a main surface opposite to the main surface of the protective film 42 in contact with the first adhesive layer 45. Is formed.

  According to the heater 1d, even when the protective film 42 has a relatively high refractive index, the reflectance of the heater 1d for near-infrared light having a wavelength of 780 to 1500 nm can be suppressed low. The low refractive index layer 40 desirably has a lower refractive index than the refractive index of the protective film 42.

  The heater 1e is a further modification of the heater 1c, and has the same configuration as that of the heater 1c, unless otherwise specified. As shown in FIG. 5, the heater 1e further includes a separator 60 and a second adhesive layer 65. Separator 60 is arranged closer to fourth main surface 14 than to third main surface 13. The third main surface 13 is a main surface of the support 10 with which the heating element 20 is in contact. The fourth main surface 14 is a main surface of the support 10 located on the opposite side of the third main surface 13. The second adhesive layer 65 is in contact with the separator 60 and the support 10 between the separator 60 and the support 10. By peeling off the separator 60, the second adhesive layer 65 is exposed. Thereafter, by pressing the second adhesive layer 65 against the adherend, the heater 1e from which the separator 60 has been removed can be adhered to the adherend. Note that the heater 1a, the heater 1b, and the heater 1d may be similarly modified.

  The separator 60 is typically a film that can maintain the adhesive strength of the second adhesive layer 65 when covering the second adhesive layer 65 and can be easily peeled off from the second adhesive layer 65. The separator 60 is, for example, a film made of a polyester resin such as polyethylene terephthalate (PET).

  The second adhesive layer 65 is formed of, for example, a known optical adhesive such as an acrylic adhesive.

  The heater 1f is a further modified version of the heater 1c, and has the same configuration as that of the heater 1c, unless otherwise specified. As shown in FIG. 6, the heater 1f further includes a molded body 80 and a second adhesive layer 65. The molded body 80 is arranged closer to the fourth main surface 14 than to the third main surface 13. The third main surface 13 is a main surface of the support 10 with which the heating element 20 is in contact. The fourth main surface 14 is a main surface of the support 10 located on the opposite side of the third main surface 13. The second adhesive layer 65 is in contact with the molded body 80 and the support 10 between the molded body 80 and the support 10. In addition, the heater 1a, the heater 1b, and the heater 1d may be similarly modified.

  The molded body 80 is, for example, a component that transmits near infrared rays having a wavelength of 780 to 1500 nm. For example, if deposits such as fog, frost, and snow adhere to the surface of the molded body 80, near-infrared rays that should pass through the molded body 80 are blocked. However, by applying a voltage to the pair of power supply electrodes 30 of the heater 1f to cause the heating element 20 to generate heat, it is possible to remove deposits such as fog, frost, and snow attached to the surface of the molded body 80. Thereby, the characteristic that the heater 1f transmits near infrared rays having a wavelength of 780 to 1500 nm can be maintained.

  The second adhesive layer 65 is not particularly limited, but is formed of, for example, a known optical adhesive such as an acrylic adhesive.

  The heater 1f can be manufactured by, for example, pressing the second adhesive layer 65 exposed by peeling the separator 60 of the heater 1e against the molded body 80 and attaching the heater 1e from which the separator 60 has been removed to the molded body 80. .

  Hereinafter, the present invention will be described in more detail with reference to examples. Note that the present invention is not limited to the following embodiments. First, an evaluation method and a measurement method for Examples and Comparative Examples will be described.

[Thickness measurement]
The thickness of the transparent conductive film (heating element) of the heater according to each example and each comparative example was measured by an X-ray reflectivity method using an X-ray diffractometer (manufactured by Rigaku Corporation, product name: RINT2200). Table 1 shows the results. Further, an X-ray diffraction pattern for the transparent conductive film was obtained using an X-ray diffraction apparatus. CuKα rays were used as X-rays. From the obtained X-ray diffraction pattern, it was confirmed whether the transparent conductive film was in a polycrystalline state or an amorphous state. The height of the end of the power supply electrode of the heater according to each example and each comparative example was measured using a stylus type surface shape measuring device (product name: Dektak8, manufactured by ULVAC), and The thickness of the power supply electrode of the heater according to the example and each comparative example was measured. The thickness of the power supply electrode of the heater according to each example and each comparative example was 20 μm.

[Sheet resistance and specific resistance]
Using a non-contact type resistance measuring device (manufactured by Napson Corporation, product name: NC-80MAP), in accordance with Japanese Industrial Standards (JIS) Z 2316: 2014, by using an eddy current measurement method in each example and each comparative example The sheet resistance of the transparent conductive film (heating element) of the heater was measured. Table 1 shows the results. In addition, the product of the thickness of the transparent conductive film (heating element) obtained by the thickness measurement and the sheet resistance of the transparent conductive film (heating element) is obtained, and the transparent conductive film of the heater according to each of the examples and comparative examples is obtained. The specific resistance of the film (heating element) was determined. Table 1 shows the results.

[Carrier density]
Using a Hall effect measurement device (manufactured by Nanometrics, product name: HL5500PC), the Hall effect measurement was performed on the film with a transparent conductive film according to each example and each comparative example according to the van der Pauw method. From the results of the Hall effect measurement, the carrier densities of the transparent conductive films (heating elements) of the heaters according to the examples and the comparative examples were determined. Table 1 shows the results.

[Crystal grain size]
Observation samples were prepared from the films with a transparent conductive film according to each example and some comparative examples. Using a transmission electron microscope (manufactured by Hitachi High-Technologies Corporation, product name: H-7650), the observation samples according to each example and each comparative example were observed, and an image in which the outline of the crystal grains was clear was obtained. . For 100 or more crystal grains in this image, the diameter of a perfect circle having an area equal to the projected area of each crystal grain was defined as the size of each crystal grain. Then, the average size for 100 or more crystal grains was determined. Table 1 shows the results.

[Argon atom concentration]
Using an ion beam analysis system (manufactured by National Electrostics Corporation, product name: Pelletron 3SDH), Rutherford backscattering spectroscopy (RBS) was performed on samples prepared from the film with a transparent conductive film according to each example and some comparative examples. ) Was measured. From this measurement result, the concentration based on the mass of argon atoms in the transparent conductive film was determined. Table 1 shows the results.

[Internal stress]
Using an X-ray diffractometer (manufactured by Rigaku Corporation, product name: RINT2200), a sample was irradiated with a Cu-Kα ray (wavelength λ: 0.1541 nm) from a 40 kV and 40 mA light source through a parallel beam optical system, The internal stress (compressive stress) of the transparent conductive film in each example and some comparative examples was evaluated based on the principle of the sin ² sin method. The sin ² Ψ method is a method of obtaining the internal stress of a thin film from the dependence of the crystal lattice strain of the polycrystalline thin film on the angle (Ψ). Using the above X-ray diffractometer, diffraction intensity was measured every 0.02 ° in the range of 2θ = 29.8 ° to 31.2 ° by {/ 2} scan measurement. The integration time at each measurement point was set to 100 seconds. From the peak angle 2θ of the obtained X-ray diffraction (peak on the (222) plane of ITO) and the wavelength λ of the X-ray emitted from the light source, the ITO crystal lattice spacing d at each measurement angle (Ψ) is calculated. Then, the crystal lattice strain ε was calculated from the crystal lattice plane distance d from the relationship of the following equations (1) and (2). λ is the wavelength of the X-ray (Cu-Kα ray) emitted from the light source, and λ is 0.1541 nm. d ₀ is the lattice spacing of the ITO in an unstressed state, where d ₀ = 0.2910 nm. The value of d _{0 is} a value described in the database of the International Center for Diffraction Data (ICDD).
2d sin θ = λ (1)
ε = (d−d ₀ ) / d ₀ (2)

As shown in FIG. 7, the angles (Ψ) between the normal to the main surface of the sample Sa of the transparent conductive film and the normal to the crystal plane of the ITO crystal Cr are 45 °, 52 °, 60 °, 70 °, and 90 °. In each case of °, the above X-ray diffraction measurement was performed, and the crystal lattice strain ε at each angle (Ψ) was calculated. Thereafter, the residual stress (internal stress) σ in the in-plane direction of the transparent conductive film was determined from the following equation (3) from the slope of a straight line plotting the relationship between sin ² Ψ and the crystal lattice strain ε. Table 1 shows the results.
ε = ｛(1 + ν) / E｝ σsin ² Ψ− (2ν / E) σ (3)

  In the above equation (3), E is the Young's modulus of ITO (116 GPa), and ν is the Poisson's ratio (0.35). These values are those described in D.G. Neerinck and T.J. Vink, “Depth Profiling of thin ITO films by grazing incidence X-ray diffraction”, Thin Solid Films, 278 (1996), P12-17. In FIG. 7, the detector 100 detects X-ray diffraction.

[Winding test]
The film with a transparent conductive film according to each example and each comparative example was cut into a strip of 20 mm × 100 mm to prepare a test piece. The test piece was wound around round bars having different diameters, and then a 100 g weight was fixed to both ends of the test piece, and the weight was suspended for 10 seconds. In addition, the film with a transparent conductive film was wound around the round bar so that the support was located closer to the round bar than the transparent conductive film (heating element). Thereafter, the presence or absence of cracks in the transparent conductive film was checked by an optical microscope. With respect to the film with a transparent conductive film according to each of the examples and the comparative examples, the maximum value of the diameter of the round bar around which the film with the transparent conductive film having a crack in the transparent conductive film was wound was specified. Table 2 shows the results.

[Scratch test]
The film with a transparent conductive film according to each example and each comparative example was cut into a strip of 50 mm × 150 mm, and the surface of the support in the film with a transparent conductive film opposite to the surface on which the transparent conductive film was formed was 25 μm. Was attached to a glass plate having a thickness of 1.5 mm via a pressure-sensitive adhesive layer having a thickness of 5 mm to prepare a sample for a scratch test. Using a 10-point pen tester, while applying a load of 1 kg with steel wool (product name: Bonstar, grade: # 0000), a 100 mm length of the exposed surface of the transparent conductive film fixed on the glass plate was applied. The area was rubbed 10 times. Furthermore, the environment of the sample after rubbing was maintained at 85 ° C. and 85% RH for 100 hours, and then the presence or absence of discoloration of the transparent conductive film was visually checked. Table 2 shows the results.

[Temperature rising characteristics]
Using a DC constant voltage power supply manufactured by Kikusui Electronics Corporation, a voltage of 12 V was applied to the pair of power supply electrodes of the heaters according to the examples and the comparative examples, and a current was applied to the transparent conductive film (heating element) of the heater. Was conducted to conduct an electric current. During the period of the power-on test, the surface temperature of the transparent conductive film (heating element) was measured using thermography manufactured by FLIR Systems, and the rate of temperature rise was calculated. The heating characteristics of the heaters according to the examples and the comparative examples were evaluated based on the heating rate according to the following criteria. Table 2 shows the results.
AA: The heating rate is 100 ° C./min or more.
A: The heating rate is 30 ° C./min or more and less than 100 ° C./min.
X: The heating rate is less than 30 ° C./min.

<Example 1>
On one major surface of a polyethylene terephthalate (PET) film having a thickness of 125 μm, indium tin oxide (ITO) (tin oxide content: 10% by weight) was used as a target material, and the surface of the target material was In a state where the magnetic flux density of the horizontal magnetic field was a high magnetic field of 100 mT (millitesla) and a small amount of argon gas was present, an ITO film having a thickness of 50 nm was formed by DC magnetron sputtering. The PET film after the formation of the ITO film was placed in the air at 150 ° C. for 3 hours to perform an annealing process. Thus, the ITO was crystallized to form a transparent conductive film (heating element). Thus, a film with a transparent conductive film according to Example 1 was obtained.

  The film with a transparent conductive film is cut into strips (short side: 30 mm × long side: 50 mm), and the transparent conductive film is masked so that a pair of ends of the transparent conductive film extending in the longitudinal direction while facing each other are exposed. Covered part of the membrane. Each of the pair of ends had a width of 2 mm. In this state, a Cu thin film having a thickness of 100 nm was formed on the transparent conductive film and the masking film by DC magnetron sputtering. Further, the Cu thin film was subjected to wet plating to increase the thickness of the Cu film to 20 μm. Thereafter, the masking film was removed, and a pair of power supply electrodes was formed at portions corresponding to the pair of ends of the transparent conductive film. Further, a PET film having a thickness of 50 μm is attached with an adhesive to a portion between the pair of power supply electrodes on the main surface opposite to the main surface of the transparent conductive film which is in contact with the PET film, and the conductive film is formed. Protected. Thus, the heater according to Example 1 was manufactured.

<Example 2>
A film with a transparent conductive film according to Example 2 was obtained in the same manner as in Example 1, except that the conditions of the DC magnetron sputtering method were changed so that the thickness of the transparent conductive film was 25 nm. A heater according to Example 2 was manufactured in the same manner as in Example 1 except that the film with a transparent conductive film according to Example 2 was used instead of the film with a transparent conductive film according to Example 1.

<Example 3>
A film with a transparent conductive film according to Example 3 was obtained in the same manner as in Example 1, except that the conditions of the DC magnetron sputtering method were changed so that the thickness of the transparent conductive film was 80 nm. A heater according to Example 3 was produced in the same manner as in Example 1 except that the film with a transparent conductive film according to Example 3 was used instead of the film with a transparent conductive film according to Example 1.

<Example 4>
A film with a transparent conductive film according to Example 4 was obtained in the same manner as in Example 1 except that indium tin oxide (ITO) (content of tin oxide: 5% by weight) was used as a target material. A heater according to Example 4 was produced in the same manner as in Example 1, except that the film with a transparent conductive film according to Example 4 was used instead of the film with a transparent conductive film according to Example 1.

<Example 5>
Example 1 was the same as Example 1 except that indium tin oxide (ITO) (tin oxide content: 15% by weight) was used as a target material and the conditions of the DC magnetron sputtering method were adjusted so that the thickness of the transparent conductive film became 50 nm. In the same manner, a film with a transparent conductive film according to Example 5 was obtained. A heater according to Example 5 was produced in the same manner as in Example 1, except that the film with a transparent conductive film according to Example 5 was used instead of the film with a transparent conductive film according to Example 1.

<Example 6>
A film with a transparent conductive film according to Example 6 was obtained in the same manner as in Example 1 except that a polyethylene naphthalate (PEN) film having a thickness of 125 μm was used instead of the PET film. A heater according to Example 6 was produced in the same manner as in Example 1 except that the film with a transparent conductive film according to Example 6 was used instead of the film with a transparent conductive film according to Example 1.

<Example 7>
A film with a transparent conductive film according to Example 7 was obtained in the same manner as in Example 1 except that a transparent polyimide (PI) film having a thickness of 125 μm was used instead of the PET film. A heater according to Example 7 was produced in the same manner as in Example 1, except that the film with a transparent conductive film according to Example 7 was used instead of the film with a transparent conductive film according to Example 1.

<Comparative Example 1>
A film with a transparent conductive film according to Comparative Example 1 was obtained in the same manner as in Example 1, except that the annealing of the ITO film was not performed. A heater according to Comparative Example 1 was produced in the same manner as in Example 1, except that the film with a transparent conductive film according to Comparative Example 1 was used instead of the film with a transparent conductive film according to Example 1.

<Comparative Example 2>
A film with a transparent conductive film according to Comparative Example 2 was obtained in the same manner as in Example 1, except that the conditions of the DC magnetron sputtering method were changed so that the thickness of the transparent conductive film was 17 nm. A heater according to Comparative Example 2 was produced in the same manner as in Example 1 except that the film with a transparent conductive film according to Comparative Example 2 was used instead of the film with a transparent conductive film according to Example 1.

<Comparative Example 3>
A film with a transparent conductive film according to Comparative Example 3 was obtained in the same manner as in Example 1, except that the conditions of the DC magnetron sputtering method were changed so that the thickness of the transparent conductive film became 140 nm. A heater according to Comparative Example 3 was produced in the same manner as in Example 1 except that the film with a transparent conductive film according to Comparative Example 3 was used instead of the film with a transparent conductive film according to Example 1.

<Comparative Example 4>
Except that the magnetic flux density of the horizontal magnetic field in DC magnetron sputtering was changed to 30 mT so that the concentration of argon atoms in the transparent conductive film was 4.6 ppm by mass, the transparent conductive material according to Comparative Example 4 was similar to that of Example 1. A film with a film was obtained. A heater according to Comparative Example 4 was produced in the same manner as in Example 1 except that the film with a transparent conductive film according to Comparative Example 4 was used instead of the film with a transparent conductive film according to Example 1.

<Comparative Example 5>
On one main surface of a polyethylene terephthalate (PET) film, a 40 nm thick IO film was formed by DC magnetron sputtering using indium oxide (IO) as a target material. Next, a 13 nm Ag film was formed on the IO film by a DC magnetron sputtering method using silver (Ag) as a target material. Next, a 40 nm IO film was formed on the Ag film by DC magnetron sputtering using indium oxide (IO) as a target material. Thus, a film with a transparent conductive film according to Comparative Example 5 was obtained. A heater according to Comparative Example 5 was produced in the same manner as in Example 1 except that the film with a transparent conductive film according to Comparative Example 5 was used instead of the film with a transparent conductive film according to Example 1.

<Comparative Example 6>
Indium tin oxide (ITO) (tin oxide content: 5% by weight) was used as a target material. In addition, the magnetic flux density of the horizontal magnetic field in DC magnetron sputtering was changed to 30 mT so that the thickness of the transparent conductive film was 400 nm and the concentration of argon atoms in the transparent conductive film was 5.2 ppm by mass. A film with a transparent conductive film according to Comparative Example 6 was obtained in the same manner as in Example 1 except for the above. A heater according to Comparative Example 6 was produced in the same manner as in Example 1 except that the film with a transparent conductive film according to Comparative Example 6 was used instead of the film with a transparent conductive film according to Example 1.

  According to the results of the winding test in Table 2, in Comparative Examples 3 and 6, the maximum value of the diameter of the round bar around which the heater in which cracks occurred in the transparent conductive film was wound was as large as 28 mm and 32 mm, respectively. . On the other hand, in Examples 1 to 7, the maximum value of the diameter of the round bar around which the heater in which cracks occurred in the transparent conductive film was wound was as small as 12 to 18 mm. Therefore, it was suggested that the transparent conductive films of the heaters according to Examples 1 to 7 have high resistance to bending.

  According to the results of the abrasion test in Table 2, in Comparative Example 5, discoloration of the transparent conductive film was confirmed, whereas in Examples 1 to 7, no discoloration of the transparent conductive film was confirmed. It was suggested that the transparent conductive film of the heater according to No. 7 had high resistance to rubbing.

  According to the results of the temperature increase characteristics in Table 2, the heaters according to Comparative Examples 1, 2, and 4 had a low temperature increase rate, whereas the heaters according to Examples 1 to 7 had a high temperature increase rate.

1a to 1f Heater 10 Support 13 Third Main Surface 14 Fourth Main Surface 20 Heating Element 21 First Main Surface 22 Second Main Surface 30 Power Supply Electrode 40 Low Refractive Index Layer 42 Protective Film 45 First Adhesive Layer 60 Separator 65 Second adhesive layer 80 molded body

Claims (12)

A sheet-like support made of an organic polymer,
A heating element that is a transparent conductive film made of a polycrystal containing indium oxide as a main component,
And at least a pair of power supply electrodes in contact with the heating element,
The thickness of the heating element is more than 20 nm and 100 nm or less,
The heating element is a resistivity of ^{1.4 × 10 -4 Ω · cm~3 ×} 10 -4 Ω · cm,
heater. The heater according to claim 1, wherein a carrier density of the heating element is 6 × 10 ²⁰ cm ^{−3 to} 16 × 10 ²⁰ cm ⁻³ .   3. The heater according to claim 1, wherein a ratio of the number of tin atoms to the sum of the number of indium atoms and the number of tin atoms in the heating element is 0.04 to 0.15. 4.   The crystal grain of the heating element has an average size of 150 nm to 500 nm, assuming that the diameter of a perfect circle having an area equal to the projected area of each crystal grain in a specific direction is the size of each crystal grain. 4. The heater according to any one of items 3 to 3.   The heater according to any one of claims 1 to 4, wherein the concentration of argon atoms contained in the heating element is 3.5 ppm or less on a mass basis.   The heater according to any one of claims 1 to 5, wherein an internal stress of the heating element measured by an X-ray stress measurement method is 20 to 650 MPa.   The heater according to claim 1, wherein the power supply electrode has a thickness of 1 μm or more.   The support according to claim 1, wherein the support is made of at least one selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polyimide, polycarbonate, polyolefin, polyetheretherketone, and aromatic polyamide. The heater according to item. It is arranged closer to the second main surface, which is the main surface of the heating element located on the opposite side of the first main surface, than the first main surface, which is the main surface of the heating element that is in contact with the support. Protective film,
Between the protective film and the heating element, further comprising a first adhesive layer in contact with the protective film and the heating element,
The heater according to any one of claims 1 to 8. It is arranged closer to the fourth main surface, which is the main surface of the support, located on the opposite side of the third main surface, than the third main surface, which is the main surface of the support, with which the heating element is in contact. Separator,
Between the separator and the support, a second adhesive layer in contact with the separator and the support,
The heater according to any one of claims 1 to 9. It is arranged closer to the fourth main surface, which is the main surface of the support, located on the opposite side of the third main surface, than the third main surface, which is the main surface of the support, with which the heating element is in contact. Molded body,
Between the molded body and the support, comprising a second adhesive layer in contact with the molded body and the support,
The heater according to any one of claims 1 to 9.   The heater according to any one of claims 1 to 11, wherein the heater is arranged on an optical path of the near-infrared ray in an apparatus that performs processing using near-infrared rays included in a wavelength range of 780 to 1500 nm.

Images