Film heaters and heated glass

Abstract

Provided is a film heater 100 comprising, in this order: a substrate 10; a first hard-coat layer 11 including a first resin component and a silica filler; a first dielectric layer 21; a metal layer 24 including one or both of silver and a silver alloy; a second dielectric layer 22; and an ITO layer 26 or an IZO layer. The metal layer 24 has a thickness of 5.5 to 7.5 nm. A peak intensity that is detected by fluorescent X-ray analysis of an upper surface 11A on the first dielectric layer 21 side of the first hard-coat layer 11 and that indicates the Kα spectral line of Si element is 15 to 35 cps.

Description

Technical Field

[0001] The present disclosure relates to a film heater and a glass with a heater.

Background Art

[0002] For glass in vehicles, outdoor display devices, buildings, etc., glass with a heater function is used to prevent fogging, melt snow, and prevent condensation. Conventionally, glass with a heater function in which nichrome fine wires are arranged in the glass has been known as such a glass with a heater function. However, in the case of such glass with a heater function, the nichrome fine wires inhibit the transmissive visibility. For this reason, using a transparent conductive film for the heater has been considered. For example, in Patent Document 1, a transparent film heater having a transparent conductive layer containing a conductive polymer and an energizing electrode on at least one side of a transparent film substrate has been proposed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Depending on the application, the film heater may be used outdoors, so it is required to have excellent durability. Also, depending on the application, it may be required to have excellent transmissive visibility. Therefore, the present disclosure provides a film heater that is excellent in durability and can sufficiently reduce the absorption rate of visible light. The present disclosure provides a glass with a heater including a film heater that is excellent in durability and can sufficiently reduce the absorption rate of visible light.

Means for Solving the Problems

[0005] This disclosure provides a film heater comprising, in this order, a substrate, a first hard coat layer containing a first resin component and a silica filler, a first dielectric layer, a metal layer containing either or both silver and a silver alloy, a second dielectric layer, and an ITO layer or an IZO layer, wherein the thickness of the metal layer is 5.5 to 7.5 nm, and the peak intensity of the Kα line of the Si element detected by X-ray fluorescence analysis of the surface of the first hard coat layer on the first dielectric layer side is 15 to 35 cps.

[0006] In the above-described film heater, the peak intensity of the Kα line of the Si element detected by X-ray fluorescence analysis of the surface of the first hard coat layer on the first dielectric layer side is greater than a predetermined value. Thus, silica filler is sufficiently exposed on the surface of the first hard coat layer on the first dielectric layer side. Because the silica filler is exposed in this way, the adhesion between the first hard coat layer and the first dielectric layer, or between the first hard coat layer and the first dielectric layer, and the layer in contact with the first hard coat layer can be sufficiently high. Therefore, the durability of the film heater can be increased.

[0007] In the above-described film heater, the peak intensity of the Kα line of the Si element detected by X-ray fluorescence analysis on the surface of the first hard coat layer on the second dielectric layer side is smaller than a predetermined value. This suppresses excessive surface irregularities of the first hard coat layer and excessive silica filler content. In addition, the thickness of the metal layer is within a predetermined range. Due to these factors, the absorption rate of visible light can be sufficiently reduced. Such a film heater can have high transparency.

[0008] The above-described film heater comprises, on the side of the substrate opposite to the first hard coat layer, a second hard coat layer containing a second resin component and a low-reflectance layer in that order from the substrate side, and the low-reflectance layer may have a refractive index smaller than that of the substrate and the second hard coat layer but larger than that of air. This reduces the reflectance when visible light incident on the surface of the film heater from the ITO layer side or the IZO layer side exits from the opposite surface of the film heater, and the transmittance of visible light can be made sufficiently high. Therefore, the transparency of the film heater can be further increased.

[0009] The above-described film heater may include a high refractive index layer between the first hard coat layer and the first dielectric layer. This makes it possible to sufficiently increase the transmittance of visible light incident from the second dielectric layer side of the film heater.

[0010] The silica filler content in the first hard coat layer relative to the first resin component may be 8 to 20% by mass. This further improves the adhesion between the first hard coat layer and the layer in contact with it, and further reduces the absorption rate of visible light.

[0011] This disclosure provides a heated glass comprising one of the above-described film heaters, an electrode on the surface of an ITO layer or IZO layer, and a glass plate facing the ITO layer or IZO layer and the electrode.

[0012] The heated glass described above is equipped with one of the aforementioned film heaters. Therefore, it has a sufficiently low visible light absorption rate and excellent durability. Such heated glass can be suitably used in applications requiring high durability and transparency. For example, it is suitably used in vehicles, outdoor display devices, and buildings. However, the applications of the heated glass described above are not limited to those mentioned above. [Effects of the Invention]

[0013] We can provide a film heater that is highly durable and capable of significantly reducing the absorption rate of visible light. We can also provide heated glass equipped with a film heater that is highly durable and capable of significantly reducing the absorption rate of visible light. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic cross-sectional view showing an example of a film heater. [Figure 2] This is a schematic cross-sectional view showing another example of a film heater. [Figure 3] This is a schematic cross-sectional view showing an example of a heated glass. [Modes for carrying out the invention]

[0015] Embodiments of this disclosure will be described below, with reference to drawings as appropriate. However, the following examples are illustrative for the purpose of explaining this disclosure and are not intended to limit this disclosure to the following. In the description, elements having the same structure or function will be given the same reference numerals, and redundant explanations will be omitted as appropriate. Furthermore, positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings unless otherwise specified. In addition, the dimensional ratios of each element are not limited to the ratios shown.

[0016] The film heater comprises, in this order, a substrate, a first hard coat layer containing a first resin component and a silica filler, a first dielectric layer, a metal layer containing either or both silver and a silver alloy, a second dielectric layer, and an ITO layer or an IZO layer. The film heater may be transparent (a transparent film heater).

[0017] In this disclosure, "ITO" refers to indium tin oxide. In this disclosure, "IZO" refers to indium zinc oxide. In this disclosure, "transparent" means that visible light is transmitted, and it may scatter light to some extent. Materials that scatter light, generally referred to as semi-transparent, are also included in the concept of "transparent" in this disclosure. For example, a film heater with a transmittance of 75% or more in the wavelength range of 360 to 740 nm is a transparent film heater. The above transmittance of a transparent film heater may be 80% or more. In this disclosure, visible light refers to light in the wavelength range of 360 to 740 nm.

[0018] The substrate in the film heater is a transparent substrate, and may be, for example, a resin substrate composed of a flexible organic resin film. The organic resin film may also be an organic resin sheet. Examples of organic resin films include polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyolefin films such as polyethylene and polypropylene, polycarbonate films, acrylic films, norbornene films, polyarylate films, polyethersulfone films, diacetylcellulose films, and triacetylcellulose films. Of these, polyester films such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) are preferred. One of the above may be used alone, or two or more may be used in combination. However, the substrate is not limited to those made of organic resin, and may be molded products of inorganic compounds such as soda-lime glass, alkali-free glass, and quartz glass.

[0019] From the viewpoint of rigidity, a thicker substrate is preferable for a film heater. On the other hand, from the viewpoint of making the film heater thinner, a thinner substrate is preferable. From this viewpoint, the thickness of the substrate is, for example, 10 to 200 μm.

[0020] The first hard coat layer contains, for example, a resin component (first resin component) obtained by curing a resin composition and silica fillers dispersed in the resin component. The resin composition preferably contains at least one selected from a thermosetting resin composition, an ultraviolet curable resin composition, and an electron beam curable resin composition. The thermosetting resin composition may contain at least one selected from an epoxy resin, a phenoxy resin, and a melamine resin.

[0021] The resin composition is, for example, a composition containing a curable compound having an energy ray reactive group such as a (meth)acryloyl group or a vinyl group. The notation of (meth)acryloyl group means including at least one of an acryloyl group and a methacryloyl group. The curable compound preferably contains a polyfunctional monomer or oligomer containing two or more, preferably three or more, energy ray reactive groups in one molecule.

[0022] The curable compound preferably contains an acrylic monomer. Specific examples of the acrylic monomer include 1,6 - hexanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, ethylene oxide modified bisphenol A di(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane ethylene oxide modified tri(meth)acrylate, trimethylolpropane propylene oxide modified tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol tri(meth)acrylate, and 3-(meth)acryloyloxy glycerin mono(meth)acrylate, etc. However, it is not necessarily limited to these. For example, urethane modified acrylate and epoxy modified acrylate are also included.

[0023] As the curable compound, a compound having a vinyl group may be used. Examples of the compound having a vinyl group include ethylene glycol divinyl ether, pentaerythritol divinyl ether, 1,6 - hexanediol divinyl ether, trimethylolpropane divinyl ether, ethylene oxide - modified hydroquinone divinyl ether, ethylene oxide - modified bisphenol A divinyl ether, pentaerythritol trivinyl ether, dipentaerythritol hexavinyl ether, ditrimethylolpropane polyvinyl ether, and the like. However, it is not necessarily limited to these.

[0024] When the resin composition is cured by ultraviolet rays, it contains a photoinitiator. Various photoinitiators can be used. For example, it may be appropriately selected from known compounds such as acetophenone - based, benzoin - based, benzophenone - based, and thioxanthone - based compounds. More specifically, Darocur 1173, Irgacure 651, Irgacure 184, Irgacure 907, Irgacure 127 (above are trade names, manufactured by Ciba Specialty Chemicals), and KAYACURE DETX - S (trade name, manufactured by Nippon Kayaku Co., Ltd.) can be mentioned.

[0025] The content of the photoinitiator may be 0.01 - 20% by mass or 1 - 10% by mass based on the mass of the resin composition. The resin composition may be a known one containing an acrylic monomer and a photoinitiator. Examples of the resin composition containing an acrylic monomer and a photoinitiator include SD - 318 (trade name, manufactured by Dainippon Ink and Chemicals, Inc.), which is ultraviolet - curable, and XNR5535 (trade name, manufactured by Nagase Sangyo Co., Ltd.).

[0026] When using a resin composition curable by energy rays, the resin composition can be cured by irradiating energy rays such as ultraviolet rays.

[0027] The average particle size of the silica filler dispersed in the resin component in the first hard coat layer may be 10 nm or more, or 20 nm or more, from the viewpoint of improving adhesion between the first hard coat layer and adjacent layers. The average particle size of the silica filler may be 200 nm or less, or 150 nm or less, from the viewpoint of ensuring sufficient transparency. This average particle size is the particle size (median diameter, D50) at which the cumulative value from the smallest particle size reaches 50% of the total in the cumulative distribution of the particle size distribution based on the number of particles measured using a particle size distribution analyzer by laser diffraction and scattering. The silica filler may be treated with a silane coupling agent, and energy-ray reactive groups such as (meth)acryloyl groups and / or vinyl groups may be formed in a film-like manner on the surface.

[0028] The silica filler content in the first hard coat layer relative to the resin component may be 8 to 20% by mass. From the viewpoint of ensuring sufficiently high adhesion between the first hard coat layer and the layer in direct contact with it (e.g., a high refractive index layer or a first dielectric layer), the lower limit of the content may be 10%, 12%, or 14% by mass. From the viewpoint of sufficiently lowering the visible light absorption rate of the film heater, the upper limit of the content may be 17% or 15% by mass. If the silica filler content is too low, the effects of thermal expansion and swelling of the resin component in high-temperature and high-humidity environments tend to increase, impairing durability. On the other hand, if the silica filler content is too high, the visible light absorption rate tends to increase.

[0029] X-ray fluorescence analysis of the surface of the first hard coat layer on the first dielectric layer side detects a peak intensity of 15-35 cps indicating the Kα line of the Si element, which is quantified by the X-ray fluorescence analysis of the surface. This peak intensity serves as an indicator of the amount of silica filler exposed on the surface of the first hard coat layer on the first dielectric layer side. In other words, a higher intensity means a greater amount of silica filler is exposed on the surface of the first hard coat layer. Since the peak intensity is above the lower limit mentioned above, the adhesion between the first hard coat layer and the first dielectric layer, or between the first hard coat layer and the first dielectric layer, can be sufficiently high. Therefore, the durability of the film heater can be increased.

[0030] From the viewpoint of further improving the durability of the film heater, the lower limit of the peak intensity may be 17 cps, 19 cps, or 25 cps. On the other hand, from the viewpoint of sufficiently reducing the visible light transmittance of the film heater, the upper limit of the peak intensity may be 30 cps or 27 cps. The measurement conditions for X-ray fluorescence analysis are as described in the examples.

[0031] The peak intensity described above can be adjusted by changing the silica filler content in the first hard coat layer.

[0032] The first hard coat layer can be formed by applying a paint (dispersion) containing a solvent, a resin composition, and a silica filler to one surface of a substrate, drying it, and curing the resin composition. This application can be carried out by known methods. Examples of application methods include the extrusion nozzle method, blade method, knife method, bar coat method, kiss coat method, kiss reverse method, gravure roll method, dip method, reverse roll method, direct roll method, curtain method, and squeeze method. A conventional organic solvent can be used as the solvent. Increasing the viscosity of the paint makes it less likely for the silica filler to settle downwards (towards the substrate). This allows for an increase in the peak intensity. From this viewpoint, the viscosity of the paint (at 20°C) is preferably, for example, 0.8 to 1.2 mPa·s.

[0033] The thickness of the first hard coat layer may be, for example, 0.1 to 10 μm, or 0.5 to 5 μm. This allows for sufficiently high adhesion between the first hard coat layer and the layer in direct contact with it (for example, a high refractive index layer or a first dielectric layer), while sufficiently suppressing the occurrence of thickness variations and wrinkles. The refractive index of the first hard coat layer may be, for example, 1.40 to 1.60. The absolute value of the difference in refractive index between the substrate and the first hard coat layer may be, for example, 0.1 or less.

[0034] One or both of the first dielectric layer and the second dielectric layer may be, for example, layers containing metal oxides different from ITO and IZO, metal oxide layers containing metal oxides (excluding ITO and IZO) as the main component, or metal oxide layers composed solely of metal oxides (excluding ITO and IZO).

[0035] The first dielectric layer may contain, for example, four components: zinc oxide, tin oxide, indium oxide, and titanium oxide, or three components: zinc oxide, indium oxide, and titanium oxide, as its main components. By containing the above four components, the first dielectric layer can be made to possess sufficiently high conductivity and transparency. Zinc oxide is, for example, ZnO, and indium oxide is, for example, In2O3. Titanium oxide is, for example, TiO2, and tin oxide is, for example, SnO2. The ratio of metal atoms to oxygen atoms in each of the above metal oxides may deviate from the stoichiometric ratio.

[0036] In this disclosure, "main component" means a component whose proportion to the whole is 80% by mass or more. The first dielectric layer may have a higher resistance than the second dielectric layer. Therefore, the tin oxide content of the first dielectric layer may be less than that of the second dielectric layer, or it may not contain tin oxide at all.

[0037] When the first dielectric layer contains three components, zinc oxide, indium oxide, and titanium oxide, it is preferable that the content of ZnO relative to the total of the three components is the highest among the three components, when the three components are converted to ZnO, In2O3, and TiO2, respectively. The content of ZnO relative to the total of the three components is, for example, 45 mol% or more, from the viewpoint of suppressing the visible light absorption rate of the first dielectric layer. In the first dielectric layer, the content of ZnO relative to the total of the three components is, for example, 85 mol% or less, from the viewpoint of sufficiently increasing durability in high temperature and high humidity environments.

[0038] In the first dielectric layer, the In2O3 content relative to the total of the three components is, for example, 35 mol% or less, from the viewpoint of suppressing the visible light absorption rate of the first dielectric layer. In the first dielectric layer, the In2O3 content relative to the total of the three components is, for example, 10 mol% or more, from the viewpoint of ensuring sufficiently high durability in high temperature and high humidity environments.

[0039] In the first dielectric layer, the TiO2 content relative to the total of the three components is, for example, 20 mol% or less, from the viewpoint of suppressing the visible light absorption rate of the first dielectric layer. In the first dielectric layer, the TiO2 content relative to the total of the three components is, for example, 5 mol% or more, from the viewpoint of ensuring sufficiently high durability in high temperature and high humidity environments. The respective content of the three components is obtained by converting zinc oxide, indium oxide, and titanium oxide to ZnO, In2O3, and TiO2, respectively.

[0040] The second dielectric layer may contain, for example, four main components: zinc oxide, indium oxide, titanium oxide, and tin oxide. By containing these four main components, the second dielectric layer can possess both conductivity and high transparency. Zinc oxide is, for example, ZnO, and indium oxide is, for example, In2O3. Titanium oxide is, for example, TiO2, and tin oxide is, for example, SnO2. The ratio of metal atoms to oxygen atoms in each of the above metal oxides may deviate from the stoichiometric ratio.

[0041] In the second dielectric layer, the zinc oxide content relative to the total of the four components is, for example, 20 mol% or more, from the viewpoint of maintaining high transparency while ensuring sufficiently high conductivity. In the second dielectric layer 22, the zinc oxide content relative to the total of the four components is, for example, 68 mol% or less, from the viewpoint of ensuring sufficiently high durability in high-temperature and high-humidity environments.

[0042] In the second dielectric layer, the content of indium oxide relative to the total of the four components is, for example, 35 mol% or less, from the viewpoint of keeping the surface resistance sufficiently low while maintaining an appropriate transmittance. In the second dielectric layer, the content of indium oxide relative to the total of the four components is, for example, 15 mol% or more, from the viewpoint of ensuring sufficiently high durability in high-temperature and high-humidity environments.

[0043] In the second dielectric layer, the titanium dioxide content relative to the total of the four components is, for example, 20 mol% or less, from the viewpoint of ensuring visible light transmittance. In the second dielectric layer, the titanium dioxide content relative to the total of the four components is, for example, 5 mol% or more, from the viewpoint of ensuring sufficiently high alkali resistance.

[0044] In the second dielectric layer, the tin oxide content relative to the total of the four components is, for example, 40 mol% or less, from the viewpoint of ensuring high transparency. In the second dielectric layer, the tin oxide content relative to the total of the four components is, for example, 5 mol% or more, from the viewpoint of ensuring sufficiently high durability in high temperature and high humidity environments. The content of each of the four components is obtained by converting zinc oxide, indium oxide, titanium oxide, and tin oxide to ZnO, In2O3, TiO2, and SnO2, respectively.

[0045] The first dielectric layer and the second dielectric layer combine the functions of adjusting optical properties, protecting the metal layer, and ensuring conductivity. The first and second dielectric layers may contain trace or unavoidable components in addition to the components described above, to the extent that their functions are not significantly impaired. However, from the viewpoint of obtaining a film heater with sufficiently high properties, it is preferable that the proportion of the three components in the first dielectric layer and the total proportion of the four components in the second dielectric layer be high. The proportions for both are, for example, 95% by mass or more, and preferably 97% by mass or more. The first dielectric layer may consist of the three components described above. The second dielectric layer may consist of the four components described above.

[0046] The composition of the first dielectric layer may be the same as or different from that of the second dielectric layer. If the first and second dielectric layers have the same composition, the manufacturing process can be simplified. The first dielectric layer may also contain the same four components as the second dielectric layer: zinc oxide, indium oxide, titanium oxide, and tin oxide. In this case, the specific proportion of each metal oxide to the total of the four components in the first dielectric layer may be the same as that of the second dielectric layer.

[0047] While the second dielectric layer is a layer mainly containing the four components mentioned above, the first dielectric layer may be a layer mainly containing zinc oxide, indium oxide, and titanium oxide. This makes it possible to reduce manufacturing costs while maintaining high transparency. In this case, although the conductivity of the first dielectric layer will be lower than that of the second dielectric layer, this does not pose any particular problem because conductivity can be ensured by the second dielectric layer.

[0048] The thicknesses of the first and second dielectric layers are, for example, 3 to 70 nm, preferably 5 to 50 nm, from the viewpoint of achieving both high transparency and high conductivity at a high level. The thicknesses of the first and second dielectric layers may be the same or different. For example, by individually adjusting the thicknesses of the first and second dielectric layers, it is possible to suppress changes in the color tone of transmitted light or to effectively utilize the optical interference effect for converting reflected light generated in the metal layer into transmitted light.

[0049] The first and second dielectric layers can be fabricated by vacuum deposition, sputtering, ion plating, or CVD. Of these, sputtering is preferred because it allows for miniaturization of the deposition chamber and offers a high deposition rate. DC magnetron sputtering is an example of a sputtering method. Oxide targets, metals, or semimetallic targets can be used as targets.

[0050] The metal layer may contain either silver or a silver alloy, or both, as its main component. The total content of silver and silver alloy in the metal layer may be, for example, 90% by mass or more, or 95% by mass or more, in terms of elemental silver. The metal layer may also contain metals (alloys) other than silver and silver alloys. For example, the environmental resistance of the metal layer can be improved by including at least one element selected from the group consisting of Cu, Ge, Ga, Nd, Pt, Pd, Bi, Sn, and Sb as a constituent element of the silver alloy or as a single metal. Examples of silver alloys include Ag-Pd, Ag-Cu, Ag-Pd-Cu, Ag-Nd-Cu, Ag-In-Sn, and Ag-Sn-Sb.

[0051] The thickness of the metal layer is 5.5 to 7.5 nm, from the perspective of sufficiently reducing the absorption rate of visible light. If the thickness of the metal layer is smaller than this range, the absorption rate of visible light increases, and transparency is impaired. In other words, if the thickness of the metal layer is too small, the absorption rate of visible light increases. On the other hand, if the thickness of the metal layer exceeds the above range, the absorption rate of visible light also increases, and transparency is impaired. Therefore, by setting the thickness of the metal layer within the above range, the absorption rate of visible light can be sufficiently reduced.

[0052] The metal layer can be formed, for example, using DC magnetron sputtering. The method for depositing the metal layer is not particularly limited, and other vacuum deposition methods using plasma or ion beams, or coating methods using liquids in which the constituent components are dispersed in a suitable binder, can be appropriately selected.

[0053] The ITO layer or IZO layer is a layer with higher electrical conductivity than the second dielectric layer. By providing the ITO layer or IZO layer, the degree of freedom in material selection for the second dielectric layer can be increased. The ITO layer may contain unavoidable impurities in addition to ITO. The IZO layer may contain unavoidable impurities in addition to IZO. By providing the ITO layer or IZO layer, contact resistance can be sufficiently reduced when electrodes are connected to the second dielectric layer. If the ITO layer or IZO layer and the second dielectric layer are in direct contact, high transparency can be sufficiently maintained while keeping the thickness of the film heater sufficiently small.

[0054] The thickness of the ITO layer (IZO layer) is, for example, 5 to 40 nm, preferably 10 to 30 nm, from the viewpoint of reducing both the reflectance and transmittance of visible light in a balanced manner.

[0055] The ITO layer (IZO layer) can be formed, for example, using DC magnetron sputtering. The method for depositing the ITO layer (IZO layer) is not particularly limited, and other vacuum deposition methods using plasma or ion beams, or coating methods using liquids in which the constituent components are dispersed in a suitable binder, can be appropriately selected.

[0056] The film heater may have one or more arbitrary layers in addition to the layers described above. For example, an organic protective layer may be provided on top of the ITO layer or IZO layer. The organic protective layer may be a hard coat layer composed of, for example, a UV-curing resin (e.g., Z-773L (product name) manufactured by Aica Kogyo Co., Ltd.) or a thermosetting resin. The film heater is suitably used for vehicles, outdoor display devices, and buildings. For example, it may be attached to the surface of a liquid crystal panel to improve the drivability of the liquid crystal. However, the applications of the heated glass are not limited to those described above. The film heater may be bonded to one side of the glass to constitute a film-heated glass.

[0057] Figure 1 is a schematic cross-sectional view showing an example of a film heater. The film heater 100 in Figure 1 comprises, in this order, a substrate 10, a first hard coat layer 11, a high refractive index layer 20, a first dielectric layer 21, a metal layer 24 containing either or both silver and a silver alloy, a second dielectric layer 22, and an ITO layer 26. The substrate 10, the first hard coat layer 11, the first dielectric layer 21, the metal layer 24 containing either or both silver and a silver alloy, the second dielectric layer 22, and the ITO layer 26 are subject to the above description.

[0058] The high refractive index layer 20 is a layer having a higher refractive index than the substrate 10, the first hard coat layer 11, and the first dielectric layer 21. The high refractive index layer 20 may be a layer (third dielectric layer) having a different composition from the first dielectric layer 21. By providing the high refractive index layer 20, the reflectance of visible light on the substrate 10 side can be reduced while increasing the freedom of material selection for the first dielectric layer 21. The high refractive index layer 20 may contain, for example, an oxide or nitride, and its refractive index may be 1.8 to 2.5. By providing such a high refractive index layer 20, the reflectance of visible light on the substrate 10 side can be sufficiently reduced. From the viewpoint of improving adhesion with the first dielectric layer 21 while sufficiently reducing the reflectance of visible light on the substrate 10 side, the high refractive index layer 20 may contain at least one selected from silicon nitride, niobium oxide, and titanium oxide.

[0059] The high refractive index layer 20 preferably contains silicon nitride. This increases its affinity with the silica filler contained in the first hard coat layer 11. Therefore, the adhesion between the first hard coat layer 11 and the high refractive index layer 20 is improved, further enhancing the durability of the film heater.

[0060] The thickness of the high refractive index layer 20 is, for example, 5 to 40 nm, preferably 10 to 30 nm, from the viewpoint of reducing both the reflectance and transmittance of visible light in a balanced manner.

[0061] The high refractive index layer 20 can be formed, for example, using DC magnetron sputtering. The method for depositing the high refractive index layer 20 is not particularly limited, and it may be deposited by other vacuum deposition methods using plasma or ion beams. Such a high refractive index layer 20 has a smooth surface.

[0062] In the film heater 100, the peak intensity of the Kα line of the Si element detected by X-ray fluorescence analysis of the surface 11A of the first hard coat layer 11 is 15 to 35 cps. Such a surface 11A has sufficient exposure of silica filler. Therefore, even if the surface of the layer (high refractive index layer 20) that contacts the surface 11A of the first hard coat layer 11 is smooth, sufficient adhesion between the first hard coat layer 11 and the high refractive index layer 20 in direct contact with it can be maintained. Consequently, the durability of the film heater 100 can be significantly increased.

[0063] A portion of the ITO layer 26, a portion of the second dielectric layer 22, and a portion of the metal layer 24 in the film heater 100 may be removed by etching or the like. In this case, a conductive pattern is formed by the metal layer 24, the second dielectric layer 22, and the ITO layer 26. A portion of the first dielectric layer 21 may also be removed by etching or the like.

[0064] Figure 2 is a schematic cross-sectional view showing another example of a film heater. The film heater 101 in Figure 2 comprises, on one surface of the substrate 10, a first hard coat layer 11, a high refractive index layer 20, a first dielectric layer 21, a metal layer 24 containing either or both silver and a silver alloy, a second dielectric layer 22, and an ITO layer 26 in this order, similar to the film heater 100 in Figure 1. These components are as described above.

[0065] In addition to the layers described above, the film heater 101 in Figure 2 is provided with a second hard coat layer 12 and a low-reflectance layer 28 on the other side of the substrate 10, in that order from the substrate 10 side. The second hard coat layer 12 may contain the same components as the first hard coat layer 11. For example, it may contain a resin component obtained by curing a resin composition (second resin component) and a filler dispersed in the resin component. The second resin component may be the same as that of the first resin component.

[0066] The filler contained in the second hard coat layer 12 may be the same silica filler as in the first hard coat layer 11, or it may be a different filler. Furthermore, the filler content in the second hard coat layer 12 may be the same as in the first hard coat layer 11, or it may be different. It may also be possible to have no filler at all. The resin component in the second hard coat layer 12 may be the same as in the first hard coat layer 11, or it may be different. The second hard coat layer 12 can be formed in the same manner as the first hard coat layer 11.

[0067] The thickness of the second hard coat layer 12 may be, for example, 0.1 to 10 μm, or 0.5 to 5 μm. This allows for sufficiently high adhesion between the second hard coat layer 12 and the layer in direct contact with it (e.g., the low-reflection layer 28), while sufficiently suppressing the occurrence of thickness variations and wrinkles. The refractive index of the second hard coat layer 12 may be, for example, 1.40 to 1.60. The absolute value of the difference in refractive index between the substrate 10 and the second hard coat layer 12 may be, for example, 0.1 or less.

[0068] The low-reflection layer 28 is a layer that reduces the reflection of visible light incident on the film heater 101 from one side of the substrate 10 (ITO layer 26) when it exits from the other side of the substrate 10 (low-reflection layer 28). In other words, the low-reflection layer 28, which forms the surface of the other side of the film heater 101, has a refractive index lower than that of the substrate 10 and the second hard coat layer 12, and higher than that of air. This increases the visible light transmittance of the film heater 101, thereby achieving even higher transparency. The refractive index of the low-reflection layer 28 may be, for example, 1.1 to 1.4.

[0069] The low-reflection layer 28 may contain, for example, a resin component obtained by curing a resin composition and a filler dispersed in the resin component. The filler is preferably hollow. This makes it possible to lower the refractive index compared to the second hard coat layer 12 and the substrate 10. The filler may be a hollow silica filler. The resin component may contain an acrylic resin. The thickness of the low-reflection layer 28 may be 10 to 300 nm, 30 to 200 nm, or 50 to 150 nm. This makes it possible to sufficiently suppress reflection while maintaining a thin film heater 101.

[0070] The film heaters in this disclosure are not limited to the examples in Figures 1 and 2. For example, film heaters 100 and 101 may each comprise any other layer. Film heater 101 may not comprise at least one of the second hard coat layer 12 and the low-reflection layer 28. Film heater 100 may comprise at least one of the second hard coat layer 12 and the low-reflection layer 28.

[0071] The visible light absorption rate of the film heaters 100 and 101 is, for example, 10.3% or less. This allows the visible light transmittance to be, for example, 80% or more. Furthermore, the surface resistivity of the ITO layer 26 of the film heaters 100 and 101 may be, for example, 5 to 30 Ω / sq., or 10 to 20 Ω / sq. Such film heaters are suitably used for vehicle glass (for example, for windshields and rear windows) where high transparency and excellent defrosting and de-fogging performance are required.

[0072] Figure 3 is a schematic cross-sectional view showing an example of a heated glass. The heated glass 200 in Figure 3 comprises the film heater 100 shown in Figure 1, a glass plate 50 facing the surface 26A of the film heater 100 on the ITO layer side, and an adhesive layer 40 between the glass plate 50 and the surface 26A. A portion of the surface 26A on the ITO layer side is covered with an electrode 60. The electrode 60 may be formed, for example, by applying silver paste to the surface 26A. After the electrode 60 is provided so as to cover a portion of the surface 26A of the ITO layer, an adhesive is applied to cover the surface 26A of the ITO layer and the electrode 60, and the glass plate 50 is positioned so as to face the surface 26A and the electrode 60. Then, the heated glass 200 is obtained by pressing the glass plate 50 against the surface 26A and the electrode 60 in a direction facing each other. The adhesive forming the adhesive layer 40 may be, for example, an optical glue.

[0073] The electrodes 60 are arranged in pairs and connected to a power supply (not shown), and the film heater 100 is heated by energizing it. This makes it possible to remove ice and frost adhering to the surface 50A of the glass plate 50. In addition, water droplets (clouding) adhering to the surface 10A opposite to the surface 26A on the ITO layer 26 side of the film heater 100 can also be smoothly removed. The temperature rise range (ΔT) of the film heater 100 may be 20 to 45°C or 25 to 40°C, based on the temperature before heating. This makes it possible to suppress excessive temperature rise on the surface 10A while maintaining sufficiently high performance in removing ice and frost on the surface 50A. From the viewpoint of achieving such a temperature rise range, the surface resistivity of the film heater is preferably 5 to 30 Ω / sq., and more preferably 10 to 20 Ω / sq.

[0074] In the example shown in Figure 3, the heated glass 200 includes a film heater 100, but is not limited to this. For example, instead of the film heater 100, the film heater 101 shown in Figure 2 may be included, or a modified version thereof may be included.

[0075] Although embodiments of the present disclosure have been described above, the present disclosure is not limited in any way to the above embodiments. For example, a modified version of the film heater 100, or a modified version of the film heater 101, may include an IZO layer instead of the ITO layer 26. In this case, the electrode 60 may be provided so as to cover a part of the surface of the IZO layer to constitute a heated glass.

[0076] This disclosure includes the following [1] to [5]. [1] comprising a substrate, a first hard coat layer containing a first resin component and silica filler, a first dielectric layer, a metal layer containing either or both silver and a silver alloy, a second dielectric layer, and an ITO layer or an IZO layer, in this order. The thickness of the aforementioned metal layer is 5.5 to 7.5 nm. A film heater in which the peak intensity of the Kα line of the Si element detected by X-ray fluorescence analysis of the surface of the first hard coat layer on the first dielectric layer side is 15 to 35 cps. [2] On the side of the substrate opposite to the side of the first hard coat layer, a second hard coat layer containing a second resin component and a low-reflectance layer are provided in this order from the substrate side, The low-reflectance layer has a refractive index smaller than that of the substrate and the second hard coat layer, and larger than that of air, as described in [1]. [3] The film heater according to [1] or [2], further comprising a high refractive index layer between the first hard coat layer and the first dielectric layer. [4] The film heater according to any one of [1] to [3], wherein the silica filler content in the first hard coat layer relative to the first resin component is 8 to 20% by mass. [5] A heated glass comprising a film heater as described in any one of [1] to [4] above, an electrode on the surface of the ITO layer or the IZO layer, and a glass plate facing the ITO layer or the IZO layer and the electrode. [Examples]

[0077] The contents of this disclosure will be described in more detail with reference to the examples and comparative examples, but this disclosure is not limited to the examples described below.

[0078] [Making a film heater] (Example 1) A polyethylene terephthalate (PET) film with a thickness of 125 μm was prepared as the substrate. A first hard coat layer was formed on one side of the PET film. Specifically, a paint was prepared by compounding a silica filler (average particle size: 100 nm, manufactured by CIK Nanotech, trade name: AB-S53), a resin composition containing an acrylic monomer (curable compound) and a photopolymerization initiator, and a solvent. As the acrylic monomer, Z-737-9AL (trade name) manufactured by Aica Kogyo Co., Ltd. was used, as the photopolymerization initiator, Irgacure 127 (trade name) manufactured by Ciba Specialty Chemicals was used, and as the solvent, methyl ethyl ketone was used. The photopolymerization initiator content, based on the mass of the resin composition, was 5% by mass. The solvent content, based on the mass of the paint, was 80% by mass. The viscosity of the paint (20°C) was 0.9 mPa·ss That was the case.

[0079] This paint was applied to one side of a PET film, dried, and cured by irradiation with ultraviolet light to form a first hard coat layer. The silica filler content in the first hard coat layer relative to the resin component was calculated to be 12% by mass, based on the amount of resin composition (monomer + photopolymer initiator) and silica filler in the paint.

[0080] A high refractive index layer was formed on the first hard coat layer by DC magnetron sputtering. This high refractive index layer was formed using a boron-doped Si target in a mixed atmosphere containing 80 volume% argon gas and 20 volume% nitrogen gas. The high refractive index layer thus formed was composed of SiN. The refractive index of the high refractive index layer was 1.9. On this high refractive index layer, a first dielectric layer, a metal layer containing a silver alloy, a second dielectric layer, and an ITO layer were formed in this order.

[0081] The first dielectric layer was formed using a ZnO-In2O3-TiO2 target, and the second dielectric layer was formed using a ZnO-In2O3-TiO2-SnO2 target. The composition (molar ratio) of each target is shown in Table 1. The first and second dielectric layers had the same composition as their respective targets.

[0082] The metal layer was formed using an Ag-Pd-Cu target. The target composition was Ag:Pd:Cu = 99.0:0.5:0.5 (mass%). The metal layer had the same composition as the target. The ITO layer was formed using an ITO target (In2O3-SnO2 target) in a mixed atmosphere of argon and oxygen gas (Ar:O2 = 98 vol%:2 vol%). The ITO target composition was In2O3:SnO2 = 92:8 (mass%). The ITO layer had almost the same composition as the ITO target.

[0083] In this way, a film heater was obtained having a PET substrate, a first hard coat layer, a high refractive index layer, a first dielectric layer, a metal layer, a second dielectric layer, and an ITO layer in this order. The obtained film heater was cut along the stacking direction using a focused ion beam (FIB) apparatus. The cross-section was observed with a transmission electron microscope to determine the thickness of each layer. As a result, the thickness of the first hard coat layer was 1.5 μm, the thickness of the high refractive index layer was 20 nm, the thickness of the first dielectric layer was 10 nm, the thickness of the metal layer was 6 nm, the thickness of the second dielectric layer was 6 nm, and the thickness of the ITO layer was 20 nm.

[0084] [Table 1]

[0085] (Examples 2-7, Comparative Examples 1-4) Film heaters for each example and comparative example were prepared in the same manner as in Example 1, except that the thickness of the metal layer was changed by adjusting the output of the DC magnetron sputtering and / or the amount of silica filler used when forming the first hard coat layer was changed. The thickness of the metal layer and the silica filler content of the first hard coat layer in the film heaters of each example and comparative example were determined in the same manner as in Example 1. The results are shown in Table 2.

[0086] [Evaluation of film heaters] <X-ray fluorescence analysis> The ITO layer, second dielectric layer, metal layer, first dielectric layer, and high refractive index layer of the film heaters in each example and comparative example were dissolved and removed by etching with acid. Fluorescent X-ray analysis was performed on the surface of the exposed first hard coat layer. A Rigaku ZSX Primus III (trade name) was used for the measurement. The measurement conditions were as follows. The peak intensity of the Si element Kα line was determined from the obtained fluorescence X-ray spectra. The results are shown in Table 2. X-ray tube: Rh 50kV50mA Spectroscopic crystal: PET Detector: PC Measurement diameter: φ30mm Measurement environment: Vacuum (Vacuum level: ≤10 Pa) Measurement width and measurement speed: 0.05° step, 6° / min

[0087] <Measurement of surface resistivity> The film heaters of each example and comparative example were cut to a size of 100 mm x 100 mm. A pair of electrodes were formed on the surface of the ITO layer of the cut sample using silver paste to obtain a sample for measurement. The surface resistivity (surface resistivity on the surface of the ITO layer) of this sample was measured using a 4-terminal resistivity meter (product name: Loresta EP, manufactured by Mitsubishi Chemical Analytec Corporation). The results are shown in Table 2.

[0088] <Evaluation of temperature rise> A 12V DC power supply was connected to the electrodes of the sample used for measurement, and the temperature (T1) after energizing for 10 minutes was measured using an infrared temperature sensor. The temperature rise (ΔT=T1-T0) from the temperature before energizing (T0=25℃) was calculated. The results are shown in Table 2.

[0089] <Measurement of visible light absorption rate> The visible light absorption rate of the film heaters in each example and comparative example was measured using a commercially available spectrophotometer (product name: CM-5, manufactured by Konica Minolta). Measurements were taken in 1 nm increments within the wavelength range of 360 to 740 nm. The average value of the measured values ​​is shown in Table 2 as the light absorption rate.

[0090] <Evaluation of adhesion> The film heaters of each example and comparative example were stored in a constant temperature and humidity chamber at 85°C and 85% RH for 240 hours. Afterward, the adhesion between the first hard coat layer and the high refractive index layer was evaluated by performing the following cross-cut test. The cross-cut test was conducted based on ASTM D 3559-B. Specifically, 11 cuts were made on the surface of the ITO layer at 1 mm intervals along the longitudinal and transverse directions to form a grid of 100 squares. Cellophane tape was then applied to the cut areas. The applied cellophane tape was peeled off, and the peeling status in the 100 squares was visually inspected. The results were classified into six stages: 5B, 4B, 3B, 2B, 1B, and 0B. "5B" was used when there was no peeling between the high refractive index layer and the first hard coat layer, and "0B" was used when the proportion of peeled areas was the highest. The measurement results are shown in Table 2.

[0091] [Table 2]

[0092] As shown in Table 2, the visible light absorption rates of the film heaters in Comparative Example 1, where the metal layer thickness was less than 5.5 nm, and Comparative Example 2, where the metal layer thickness was greater than 7.5 nm, exceeded the target value of 10.3%. Furthermore, in Comparative Example 1, the surface resistivity was high, and ΔT tended to be too small. In Comparative Example 2, the surface resistivity was low, and ΔT tended to be too large.

[0093] In Comparative Example 3, where the peak intensity of the silicon element Kα rays was insufficient, the adhesion between the first hard coat layer and the high refractive index layer was reduced, and insufficient durability was confirmed. This is thought to be due to a decrease in the amount of silica filler exposed on the surface of the first hard coat layer (the interface between the first hard coat layer and the high refractive index layer). On the other hand, in Comparative Example 4, where the intensity of the fluorescent X-rays was excessive, the visible light absorption rate exceeded the target value of 10.3%. This is presumed to be due to an excessive amount of silica filler.

[0094] On the other hand, each example exhibited sufficiently low visible light absorption and excellent adhesion between the high refractive index layer and the first hard coat layer. Furthermore, ΔT was within a reasonable range, confirming its usefulness in a wide range of applications. [Industrial applicability]

[0095] This disclosure provides a film heater that is highly durable and capable of sufficiently reducing the absorption rate of visible light. It also provides a heated glass equipped with a film heater that is highly durable and capable of sufficiently reducing the absorption rate of visible light. [Explanation of Symbols]

[0096] 10...Substrate, 10A, 11A, 26A, 50A...Surface, 11...First hard coat layer, 12...Second hard coat layer, 20...High refractive index layer, 21...First dielectric layer, 22...Second dielectric layer, 24...Metal layer, 26...ITO layer, 28...Low reflectivity layer, 40...Adhesive layer, 50...Glass plate, 60...Electrode, 100, 101...Film heater, 200...Glass with heater.

Claims

1. The material comprises, in this order, a substrate, a first hard coat layer containing a first resin component and a silica filler, a high refractive index layer in direct contact with the first hard coat layer, a first dielectric layer, a metal layer containing one or both of silver and a silver alloy, a second dielectric layer, and an ITO layer or an IZO layer. The thickness of the metal layer is 5.5 to 7.5 nm. The peak intensity of the Kα line of the Si element detected by X-ray fluorescence analysis of the surface on the high refractive index side of the first hard coat layer is 15 to 35 cps. The aforementioned high refractive index layer contains silicon nitride, in a film heater.

2. On the side of the substrate opposite to the first hard coat layer side, a second hard coat layer containing a second resin component and a low-reflectance layer are provided in this order from the substrate side. The film heater according to claim 1, wherein the low-reflectance layer has a refractive index smaller than that of the substrate and the second hard coat layer, and larger than that of air.

3. The film heater according to claim 1 or 2, wherein the thickness of the metal layer is 5.5 to 6.1 nm.

4. The film heater according to claim 1 or 2, wherein the silica filler content in the first hard coat layer relative to the first resin component is 8 to 20% by mass.

5. A heated glass comprising a film heater according to claim 1 or 2, an electrode on the surface of the ITO layer or the IZO layer, and a glass plate facing the ITO layer or the IZO layer and the electrode.

Images