JP2011158888A - Reflector and visible light reflection member using the reflector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reflector which has visible light reflectance of 93% or more as an electrode member of a display device or a solar battery and further can improve durability. <P>SOLUTION: The reflector is formed on a base material, and has a metal oxide layer and a reflection layer consisting of Ag doped with an element having a smaller atomic radius than that of Ag from a side near the base material when seen from a base material side, wherein crystallite size calculated from diffraction peaks originating in Ag by X-ray diffraction measurement using Cu K-alpha beam of the reflector, is 2 to 23 nm. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a reflector that reflects visible light used as a reflective member of a display device or a solar cell.

  Conventionally, a reflector using a metal film formed on a base material as a reflective layer for visible light has been employed as a reflective member used in a backlight unit of a liquid crystal display or a reflector such as a projection television. The reflector is often composed of a metal layer having a high visible light reflectivity and an inorganic layer for the purpose of protecting or enhancing the reflection of the metal layer formed on the metal layer. As the layer, Al or Ag formed by a vacuum deposition method such as sputtering is widely used (Patent Documents 1 and 2).

  Ag has a higher reflectance than Al, and it is desirable to use Ag from the viewpoint of improving the brightness of the display and saving energy (Patent Document 3), and also because it has a high reflectance. For the purpose of reflecting the light transmitted through the photoelectric conversion layer of the thin film solar cell and further improving the conversion efficiency, it is also used as a back electrode film of the thin film solar cell (Patent Document 4).

  On the other hand, the Ag film easily aggregates, and there is a problem that the aggregation causes a decrease in reflectance and peeling of the Ag film from the substrate.

  The agglomeration was caused by the adsorption of halogen ions in the atmosphere together with moisture on the Ag film surface. Furthermore, there is a problem that Ag atoms diffuse and aggregate due to heat from the light source, leading to a decrease in reflectance. For the above problems, an adhesion layer such as an oxide film or a nitride film that suppresses aggregation by forming a layer for the purpose of protection on the surface of the Ag film, or by adhering to the Ag film, is an upper layer of the Ag film. Or measures such as forming in the lower layer were taken (Cited document 5).

  Further, in addition to the above problems, sulfur in the atmosphere reacts with the Ag film and the surface is sulfided, resulting in a black discoloration, and chlorine in the atmosphere reacts with the Ag film and the surface is chlorinated. As a result, it may become cloudy (Patent Document 6). As a method for improving the above sulfidation and chlorination, there has been proposed a method of alloying an Ag film by adding a metal such as Au, Pd, Cu, or Al to the Ag film (Patent Documents 7 and 8).

JP 2002-267823 A JP 2007-310335 A International Publication WO2007 / 013269 Pamphlet JP 2003-101052 A JP-A-2005-250229 JP 2006-10930 A JP 2000-109943 A JP 2001-221908 A

  A reflector using an Ag film used as a reflection member of the display device or solar cell described above generally reflects 93% or more of visible light.

  On the other hand, since the above reflector is exposed to the atmosphere during storage until it is incorporated into a display device, there is a risk of alteration due to moisture, chlorine, or sulfur in the atmosphere. However, in addition to the above factors, it is also affected by factors such as heat and light from the light source, so these elements alone or in combination may induce Ag aggregation, resulting in peeling or clouding of the film surface. There is. For this reason, the reflector needs to have high durability against factors that cause aggregation of Ag, such as moisture, chlorine, and sulfur.

  Thus, an object of the present invention is to provide a reflector that has a visible light reflectance of 93% or more as an electrode member of a display device or a solar cell, and can further improve durability.

  As a result of intensive studies by the present inventors, it has been found that the above-mentioned problems can be solved by doping the Ag film with an element having an atomic radius smaller than that of Ag.

  That is, the reflector of the present invention is a reflector formed on a substrate, and the reflector is an atom smaller than the metal oxide layer and Ag from the side closer to the substrate as viewed from the substrate side. A reflection layer made of Ag doped with an element having a radius, and a crystallite size calculated from a diffraction peak derived from Ag is 2 by X-ray diffraction measurement using CuKα rays of the reflector. It is ˜23 nm.

  The element doped in the reflective layer can be detected by a measuring method such as fluorescent X-ray analysis or secondary ion mass spectrometry.

  The crystallite size is preferably determined from a diffraction peak derived from the (111) plane of Ag. When the crystallite size is less than 2 nm, preferred reflection characteristics may not be obtained. When the crystallite size exceeds 23 nm, a reflector with improved durability, which is the object of the present invention, cannot be obtained.

  The reflector of the present invention is characterized in that diffraction peaks derived from the (111) plane and the (200) plane of Ag are obtained by X-ray diffraction measurement using CuKα rays.

  The reflector of the present invention is characterized in that the thickness of the reflective layer is 50 to 500 nm.

  When the film thickness is less than 50 nm, visible light is transmitted through the reflective layer, so that sufficient reflectance cannot be obtained. Further, since visible light will not be transmitted if the thickness of the reflective layer is about 150 nm, the upper limit is not particularly limited, but considering the cost, it may be 500 nm or less. More preferably, it may be 150 nm or more and 300 nm or less.

  Further, the metal oxide layer of the reflector of the present invention is ZnO. ZnO has good adhesion to the Ag film, and by using ZnO as the metal oxide layer in the lower layer of the Ag film, aggregation of the Ag film can be suppressed and peeling of the Ag film from the substrate can be prevented. .

  The reflector of the present invention realizes a visible light reflectance of 93% or more and durability at the same time as a reflective member of a display device or a solar cell. One of the preferred embodiments of the present invention is to prevent the Ag film from peeling from the substrate.

It is the top view which showed the outline of the sputtering device used for formation of a reflector. It is a cross-sectional schematic diagram of the reflector formed on the glass of this invention. 6 is a schematic cross-sectional view of an Ag film formed on the glass of Comparative Example 3. FIG. It is a graph which shows the diffraction pattern of Examples 1, 2 and Comparative Examples 1-4 by X-ray diffraction method.

  One preferred embodiment of the present invention is a reflector in which a metal oxide layer is formed on a substrate and a reflective layer is formed on the metal oxide layer. The Ag film as the reflective layer is easily peeled off from the base material because of poor adhesion to the base material. However, by forming a ZnO film as a metal oxide layer between the Ag film and the base material, It becomes possible to improve the adhesiveness.

  The reflective layer is made of an Ag film, and is doped with an element having an atomic radius smaller than that of Ag. The element includes at least one selected from the group consisting of H, B, C, N, O, P and S, and the content with respect to Ag is not particularly limited as long as it does not impair the reflectance of the Ag film. Although it is not a thing, it is preferable that it is 0.001-2 mass% with respect to Ag.

  In addition to the above elements, the reflective layer is selected from Group 6 to Group 11 elements and Al, Ti, In, Ta, Bi, and Nd as long as the reflectance of the Ag film is not impaired. An element may be contained as long as the content with respect to Ag is 5% by mass or less.

As the metal oxide layer, ZnO or a film obtained by adding Al ₂ O ₃ , Ga ₂ O ₃ , SnO ₂ or the like to ZnO is preferably used, and Al ₂ O ₃ , Ga ₂ O ₃ is 1 with respect to ZnO. 10 wt%, preferably SnO ₂ is contained 1 to 45% by weight. In particular, it is preferable to use a ZnO (hereinafter sometimes referred to as AZO) film in which Al ₂ O ₃ is added to ZnO because adhesion with the Ag film is improved. Furthermore, Al ₂ O ₃ , TiO ₂ , SnO ₂ or the like can be suitably used for the metal oxide layer other than ZnO.

  In addition, the reflector may be sequentially laminated with a base material, a metal oxide layer, and a reflective layer, and may further be repeatedly laminated with one or more layers such as a metal oxide layer and a reflective layer. In addition, one or more layers may be interposed between the substrate and the metal oxide layer as long as the reflection characteristics are not impaired, and one or more layers may be laminated on the uppermost reflective layer. .

  The intervening film and the laminated film are a dielectric film such as a transparent oxide film such as Si, Sn, Al and Ti, a nitride film such as Si, Sn, Zn, Al and Ti, or a nitride oxide film. Take as an example. Further, when the dielectric layer is formed on the reflective layer, Zn, Sn, Ti, Al, NiCr, Cr are used as protective barrier layers for the reflective layer in order to prevent the reflective layer from being deteriorated due to oxidation or the like. Alternatively, a film containing Zn alloy, Sn alloy, or the like may be used. Note that “on the base material” may be a film formed in contact with the base material or another film interposed between the base material and the film.

  In addition, the obtained reflector has a 2θ position of diffraction lines attributed to the (111) plane of Ag of 37.9 ° to 38.4 ° by an X-ray diffraction measurement using CuKα rays. ) 2θ positions of diffraction lines belonging to the plane are observed at 43.9 ° to 44.5 °. If the 2θ position of the diffraction line deviates from the above range, formation of a nitride film and a decrease in reflectance may be observed.

  A polymer film or glass is preferably used for the substrate. The polymer film is not particularly limited, and examples thereof include polyethylene terephthalate resin, polyethylene naphthalate resin, polycarbonate resin, polyvinyl chloride resin, polyethylene resin, and cellulose triacetate. In any film, surface treatment such as easy adhesion, easy slipping, corona, antistatic, hard coat, and kneading with an ultraviolet absorber or the like may be performed. Examples of glass include quartz glass, float plate glass made of soda-lime silicate glass used for construction, vehicles, and displays, alkali-free glass, borosilicate glass, low expansion glass, and zero expansion glass. , Low expansion crystallized glass, zero expansion crystallized glass, glass for PDP, substrate glass for optical film, and the like.

  The reflector of the present invention is preferably formed using a sputtering method, a physical vapor deposition method such as electron beam evaporation or ion plating, or a chemical vapor deposition method such as CVD. The sputtering method is suitable because it is easy to ensure uniformity. Considering productivity, it is most preferable to form a film by a sputter film forming machine as shown in FIG. Note that FIG. 1 will be described in detail in an embodiment described later.

When forming a metal oxide layer, the target used may be either a ceramic target or a metal target. In either case of using a ceramic target or a metal target, Ar gas and O ₂ gas are introduced from the gas introduction pipe, and the mixing ratio of Ar gas and O ₂ gas may be appropriately determined according to the target film. There is no particular limitation. Moreover, when using the ZnO alloy as described above for the metal oxide layer, it is preferable to use a Zn target or a ZnO target containing Al, Ga, Sn, or the like. Further, the gas introduced into the vacuum chamber may include an optional third component other than Ar gas and O ₂ gas.

  When forming a reflective layer, a metal target is used as a target to be used, and a gas serving as one or more element sources of H, B, C, N, O, P, and S is introduced from a gas introduction pipe. To form a film. Further, the metal target may be a target containing the above-mentioned different elements in Ag, and a target containing an element selected from the group 6 to group 11 elements and Al, Ti, In, Ta, Bi, and Nd described above. May be used.

It is preferable to use a mixed gas of Ar and N _{2 as} the introduced gas when forming the reflective layer, and the gas concentration represented by [N ₂ / (Ar + N ₂ )] × 100 of the mixed gas is used. It is preferable to set it as 5-90 volume%. The gas concentration is more preferably 10% by volume or more and 30% by volume or less. When the reflective layer is formed, the crystallite size of Ag contained in the reflective layer decreases as the concentration of N ₂ gas added to the introduced gas is increased.

About the reflector of this invention, when the reflector was immersed in salt water as a durability test with respect to chlorine, when said mixed gas concentration was less than 5 volume%, durability improvement was not seen. On the other hand, if it exceeds 90% by volume, the discharge becomes unstable and a homogeneous thin film may not be obtained. The reflection layer formation rate decreases as the gas concentration of N ₂ increases, but the durability of chlorine should be reduced as much as possible from the viewpoint of productivity because the gas concentration shows sufficient performance when the gas concentration is about 10% by volume. Is preferred.

In addition to N ₂ , H ₂ , NH ₃ , CH ₄ , O ₂ , CO ₂ , B ₂ H ₆ , PH ₃ , SO _2, etc., and a mixed gas of Ar or a mixed gas of these mixed gases, etc. Since a similar effect can be obtained with a gas containing an element having a small atomic radius with respect to Ag, a mixed gas of these may be used. Further, the mixed gas may contain an optional third component. Further, the type and mixing ratio of the mixed gas may be appropriately determined in consideration of the reflectivity and durability of the reflective layer, price, safety, discharge stability, and the like.

  When forming the reflector of the present invention, as shown in FIG. 1, the base material 3 is held by the substrate holder 2, the main valve 6 is opened, and the vacuum chamber 5 is evacuated using the vacuum pump 5. Further, an introduction gas corresponding to the target 1 is introduced from the gas introduction pipe 7 into the vacuum chamber 8 by a mass flow controller (not shown), and the pressure in the vacuum chamber 8 is adjusted. The type of vacuum pump and the number and type of targets may be selected as appropriate and are not particularly limited.

  The substrate holder 2 holding the substrate 3 has a movable structure, and the film thickness during film formation can be changed by adjusting the moving speed of the substrate holder. The moving speed is constant and is not changed while the substrate is moving in the apparatus.

  Either a DC power source, an AC power source, or a power source in which AC and DC are superimposed can be used as the plasma generation source, but the DC power source is preferably used because it has excellent continuous productivity and the lowest cost. It is done. When the discharge is unstable, a power source in which alternating current and direct current are superimposed is also preferably used.

  In addition, as a preferred embodiment of the present invention, there is a visible light reflecting member in which a reflector of the present invention is laminated on a base material, and a reflection increasing layer is laminated on the reflector. The above-described increased reflection layer is formed by laminating a low-refractive index layer and a high-refractive index layer an arbitrary number of times. The reflectance is 97% or higher, which is higher than that of the conventional reflector.

  The visible light reflecting member may be laminated with a base material, a reflective reflection film, and a reflector, or may be laminated with a base material, a reflector, and a reflective reflection film. The increased reflection film may be laminated with a high refractive index layer and a low refractive index layer from the substrate side, or may be laminated with a low refractive index layer and a high refractive index layer from the substrate side. Also good. Further, the reflectance of the visible light reflecting member between the substrate and the increased reflection film, the substrate and the reflector, the increased reflection film and the reflector, or the high refractive index layer and the low refractive index layer. 1 layer or more of metal films, oxide films, nitride films, and nitride oxide films may be interposed.

The high refractive index layer and the low refractive index layer preferably have a refractive index difference of 0.05 to 2.00, more preferably 0.50 to 1.50. Further, SiO ₂ , Al ₂ O ₃ or the like is suitably used for the low refractive index layer, and Nb ₂ O ₅ , TiO ₂ or the like is suitably used for the high refractive index layer. Further, both the low refractive index layer and the high refractive index layer may be a single layer or a plurality of layers.

  The visible light reflecting member of the present invention has a visible light reflectance of 97% or more at a wavelength of 550 nm. The visible light reflecting member is suitably used as a reflecting member for a display device such as a liquid crystal display or a projection television. Furthermore, since it is less likely to cause white turbidity than conventional Ag films, it can be used outdoors.

  Moreover, since the reflector of this invention can reflect near-infrared rays, it is applicable to the heat | fever reflection sheet | seat etc. in which heat insulation is requested | required.

  In addition, the reflector of the present invention can be preferably used because it has a specific resistance of 30 μΩcm or less required as a reflective electrode member for liquid crystal displays and solar cells.

First, for the Ag film formed in a gas atmosphere containing N ₂ , N present in the film was confirmed by the following method.

  N in the Ag film was evaluated using a fluorescent X-ray analyzer (ZSX Primus II, manufactured by Rigaku Corporation). In performing X-ray fluorescence analysis, a sample in which an Ag film was directly formed on glass was used in order to detect N with higher sensitivity.

Using a sputtering method, an Ag film having a film thickness of 150 nm is formed on a plate glass with a sputtering gas atmosphere of Ar 100 volume%, a pressure in the vacuum chamber at the time of formation of 0.3 Pa, and an output voltage of a DC power source of 0.36 kW. Reference Example 1 was obtained. Further, an Ag film was formed in the same manner as in Reference Example 1 except that the sputtering gas atmosphere was changed to Ar 40 volume% and N ₂ 60 volume%, and Reference Example 2 was obtained.

  Table 1 shows the measurement results by fluorescent X-ray analysis. In Reference Example 1 and Reference Example 2, the peak angle was fixed at 47.012 °, the background angles were fixed at 44.912 ° and 52.010 °, and X-rays were irradiated for a long time in order to perform more sensitive measurement. The fluorescent X-ray intensity at a wavelength corresponding to N-Kα obtained at that time was measured. The measurement samples of Reference Example 1 and Reference Example 2 were each used in two pieces, and each sample was measured three times each. Peak intensity, background intensity (hereinafter sometimes referred to as BG intensity), peak intensity The average value was calculated with respect to the difference between the BG intensity and the BG intensity (peak intensity−BG intensity). Table 1 also shows the standard deviation σ for each sample.

From the difference between the peak intensity and the BG intensity in Table 1 (peak intensity−BG intensity), the Ag film formed at an N ₂ gas concentration of 60% by volume has a peak compared to the case where the N ₂ gas is not added. It was found that the strength was high. In addition, the peak intensity, BG intensity, and the difference between peak intensity and BG intensity were not significantly different between the two-piece measurement samples, and the standard deviation was also small, so the peak intensity increased by adding N ₂ It can be said that was confirmed. Therefore, the above peak was shown to be derived from the N _2.

  The present invention will be described in detail below based on examples.

Example 1
As shown in FIG. 2, a ZnO film 13 with a film thickness of 30 nm is formed on the substrate 3 and an Ag film 14 with a film thickness of 100 nm is formed on the ZnO film 13 in sequence using the sputtering apparatus shown in FIG. did. As the substrate, soda lime glass having a thickness of 3 mm was used.

As the sputtering apparatus, a DC magnetron sputtering apparatus having a schematic structure as shown in FIG. 1 was used. FIG. 1 shows a main part when the apparatus is observed from above. A Zn target was used for the upstream target 1, an Ag target was used for the downstream target 1, and the plate glass 3 was held by the substrate holder 2, and then the vacuum chamber 8 was evacuated using the vacuum pump 5. As the sputtering gas, an O ₂ gas was introduced when the ZnO film was formed, and a gas obtained by adding 9 sccm of N ₂ gas to the Ar gas of 36 sccm (N ₂ gas concentration of 20% by volume) was used when forming the Ag film.

  In the present invention, the number of targets 1 and backing plates 11 to be installed is appropriately set according to the number of films stacked, film type, and the like.

In forming the ZnO film 13, O ₂ gas was introduced into the atmospheric gas in the vacuum chamber 8 from the gas introduction pipe 7, and the pressure in the vacuum chamber 8 during film formation was adjusted to 0.3 Pa by the opening / closing valve 6. . Furthermore, the output power of the DC power source was 1.0 kW. The base material holder 2 was transported on the transport roll 12 and passed next to the target 1 to obtain a ZnO film.

In the formation of the Ag film 14, Ar and N ₂ gas are introduced into the atmospheric gas in the vacuum chamber 8 from the gas introduction pipe 7, and at that time, N calculated by [N ₂ / (N ₂ + Ar)] × 100 _The concentration of ₂ gases was 20% by volume. The pressure in the vacuum chamber 8 during film formation was adjusted to 0.3 Pa by the opening / closing valve 6. Furthermore, the output power of the DC power source was 0.36 kW. The base material holder 2 was transported on the transport roll 12, passed through the target 1, and obtained a reflector in which the Ag film was doped with N element.

Example 2
A reflector was formed in the same manner as in Example 1 except that a gas obtained by adding 27 sccm of N ₂ gas to 18 sccm of Ar gas (N ₂ gas concentration 60% by volume) was used as the sputtering gas for forming the Ag film 14. .

Comparative Example 1
A reflector was formed in the same manner as in Example 1 except that only Ar gas of 45 sccm (N ₂ gas concentration: 0 vol%) was used as the sputtering gas for forming the Ag film.

Comparative Example 2
The reflector was prepared in the same manner as in Example 1 except that a gas obtained by adding ₂ sccm of N ₂ gas to Ar gas 43 sccm (N ₂ gas concentration 4.4 vol%) was used as the sputtering gas for forming the Ag film 14. Formed.

Comparative Example 3
An Ag film 14 having a film thickness of 100 nm was formed on the base material 3 as shown in FIG. 3 using a sputtering apparatus as shown in FIG. As the sputtering gas, only Ar gas 45 sccm (N ₂ gas concentration 0 volume%) was used, and the formation method of the Ag film 14 was the same as that of Example 1.

Comparative Example 4
An Ag film was formed in the same manner as in Comparative Example 3 except that a gas obtained by adding 9 sccm of N ₂ gas to 36 sccm of Ar gas (N ₂ gas concentration 20% by volume) was used as the sputtering gas for forming the Ag film 14. .

(X-ray diffraction measurement)
The crystallinity of the film was evaluated by X-ray diffraction using CuKα rays using an X-ray diffraction measurement apparatus (Rint-ultima III, manufactured by Rigaku Corporation). From the measured diffraction lines, the intensities I ₍₂₀₀₎ and I ₍₁₁₁₎ of the diffraction lines on the Ag (200) plane and the Ag (111) plane were obtained, and the intensity ratio I ₍₂₀₀₎ / I ₍₁₁₁₎ was calculated. In addition, the crystallite size was calculated from the half width of the diffraction line derived from the Ag (111) plane using Scherrer's equation. A general-purpose program JADE ⁶ attached to the apparatus was used for calculation of diffraction line intensity and crystallite size.

(Evaluation of optical properties)
Using a spectrophotometer (U-4000, manufactured by Hitachi, Ltd.), light was incident from the film surface side and measured, and the reflectance at 550 nm was obtained.

(Evaluation of resistivity)
The sheet resistance of the reflector was measured using a 4-probe resistance meter (RT-70 / RG-7B, manufactured by Napson), and the specific resistance was calculated from the product of the sheet resistance and the film thickness of the Ag film.

The film thickness of the ZnO film, the film thickness of the Ag film, the N ₂ gas concentration when forming the Ag film 14, and the intensity ratio I ₍₂₀₀₎ / I _{(111) of} Example 1, Example 2 and Comparative Examples 1 to 4 Table 2 shows the crystallite size, reflectance, and specific resistance. The X-ray diffraction measurement results are shown in FIG. The reason that the intensity ratio in Comparative Example 1 and Comparative Example 2 is 0 is that the diffraction peak due to the Ag (200) plane was not obtained and only the diffraction peak of the Ag (111) plane was obtained.

From Table 2, Comparative Example 1 and Comparative Example 2 are Ag films formed with an N ₂ gas concentration of 0% by volume or 4% by volume, but no diffraction peak due to the Ag (200) plane is observed and strong (111 ) Oriented. On the other hand, in Example 1 and Example 2 in which the N ₂ gas concentration was further increased, two diffraction peaks due to the Ag (111) plane and the Ag (200) plane were obtained. From these results, it was found that the orientation of the Ag film changes depending on the nitrogen concentration.

In Example 1 using the ZnO film as the metal oxide layer and Comparative Example 4 not using the same, the Ag film is formed at the same N ₂ gas concentration, but the peak intensity ratio I ₍₂₀₀₎ / I ₍₁₁₁₎ was 0.06 and 3.79, respectively, and the orientation of the Ag film was greatly different depending on the ZnO film. From Examples 1 and 2, and Comparative Examples 1 to 4, the crystallite size tended to decrease as the N ₂ gas concentration increased.

Further, in Examples 1 and 2, and Comparative Examples 1 to 4, there was no significant difference in reflectance. Further, from Examples 1 and 2, and Comparative Examples 1 to 4, the specific resistance tends to increase as the N ₂ gas concentration is increased, but the specific resistance increases only slightly. .

(Evaluation of chlorine durability)
The reflector or the Ag film was immersed in a 5% by mass NaCl aqueous solution together with the base material, and after the immersion, the state of deterioration of the Ag film surface and the state of peeling at the interface were observed.

  Table 3 shows the evaluation results of Example 1, Example 2, and Comparative Examples 1 to 4. The immersion time was 30 minutes, 1 hour, and 3 hours. The evaluation of the deterioration state of the Ag film surface was evaluated as ◯ when no abnormality was observed, Δ when slightly cloudy was observed, and × when cloudy. In addition, the evaluation of the state of peeling at the interface was evaluated as “◯” when no abnormality was observed, “Δ” when cloudy or peeling in a minute area was observed, and “X” when more than half of the area was peeled off.

(Evaluation of surface roughness)
Using an atomic force microscope (SPM-9600, manufactured by Shimadzu Corporation), the surface shape of the reflector or Ag film before immersion in salt water and after immersion for 1 hour is measured, and the arithmetic average roughness is measured by a program attached to the apparatus. Ra was calculated. Table 4 shows the evaluation results of Example 1, Comparative Example 1, Comparative Example 3, and Comparative Example 4.

  From Table 3, the reflector obtained in Example 1 and Example 2 and the Ag film obtained in Comparative Example 4 were not confirmed to deteriorate on the film surface and film interface in the 1 hour salt water immersion test. Even when immersed for a long time, the membrane surface only slightly deteriorated, and the chlorine durability was remarkably excellent. On the other hand, in Comparative Example 1 and Comparative Example 2, the film surface deteriorated by immersion for only 30 minutes, and the chlorine durability was inferior. Further, in Comparative Example 3, the interface peeled off after immersion for only 30 minutes, and the chlorine durability was remarkably inferior.

  As described above, Ag aggregation can be cited as one of the causes of the deterioration of the Ag film surface. However, since all Ag films with high chlorine durability have a small crystallite size, As a result of suppressing the aggregation, it was shown that the deterioration of the film surface of the Ag film was improved.

  Further, from Table 4, the surface roughness of Comparative Example 3 and Comparative Example 4 after being immersed in salt water for 1 hour is larger than that of Example 1 and Comparative Example 1, and by using a ZnO film, It can be seen that an increase in the surface roughness when immersed in can be suppressed.

  From the above, it was revealed that the reflectors of Example 1 and Example 2 have excellent chlorine durability.

Example 3 to Example 5
A reflector was formed in the same manner as in Example 1 except that the thickness of the Ag film 14 was changed to 50 nm (Example 3), 150 nm (Example 4), and 250 nm (Example 5).

Example 6 to Example 8
Except for the film thickness of the Ag film 14 being 150 nm and the film thickness of the ZnO film 13 being 5 nm (Example 6), 15 nm (Example 7), and 60 nm (Example 8), everything was the same as Example 1. A reflector was formed.

The ZnO film thickness and Ag film thickness of Examples 3 to 8 and the N ₂ gas concentration, intensity ratio I ₍₂₀₀₎ / I ₍₁₁₁₎ , crystallite size, reflectance, and specific resistance when forming the Ag film 14 are shown. This is shown in FIG.

  Table 6 shows the evaluation results of chlorine durability of Examples 3 to 8. The reflector was immersed in a 5 mass% NaCl aqueous solution for 30 minutes, 1 hour, and 3 hours together with the base material, and after the immersion, the state of deterioration of the Ag film surface and the state of peeling at the interface were observed.

  From Table 5, Example 3 to Example 8 have a crystallite size of 20 nm or less, and more suitable reflectance and specific resistance, regardless of the thickness of the ZnO film or the thickness of the Ag film. It was. In Example 3, the reflectance is low and the specific resistance is high as compared with Examples 4 to 8. This is because the film thickness of Ag is thin.

  From Tables 5 and 6, it was found that even when the thickness of the Ag film was changed in the range of 50 to 250 nm, extremely strong chlorine durability was exhibited regardless of the thickness of Ag. Further, from Example 1 and Examples 3 to 5, the reflectance is improved in a reflector having an Ag film thickness of 150 nm or more.

  Furthermore, in Examples 6 to 8, even when the thickness of the ZnO film was changed in the range of 5 to 60 nm, good reflectance and chlorine durability were exhibited regardless of the thickness of ZnO.

Example 9
A polyethylene terephthalate resin film (hereinafter sometimes referred to as a PET film) with a hard coating on one side having a thickness of 188 μm was used as a substrate, and a reflector was formed on the hard coating treatment. The reflectors were all formed in the same manner as in Example 1 except that the thickness of the Ag film 14 was 150 nm.

Example 10
A reflector was formed in the same manner as in Example 9 except that the metal oxide layer was Al-doped ZnO (hereinafter sometimes referred to as AZO) formed using a ZnAl (Al 4 mass% containing Zn) target. .

Comparative Example 5
A reflector was formed in the same manner as in Example 9 except that only Ar gas of 45 sccm (N ₂ gas concentration: 0% by volume) was used as the sputtering gas for forming the Ag film.

Comparative Example 6
A reflector was formed in the same manner as in Example 10 except that only Ar gas 45 sccm (N ₂ gas concentration 0 volume%) was used as the sputtering gas for forming the Ag film 14.

Comparative Example 7
An Ag film 14 having a film thickness of 150 nm was formed on the hard coat treatment surface side using a sputtering apparatus shown in FIG. 1 on a PET film having a thickness of 188 μm. As the sputtering gas, only Ar gas 45 sccm (N ₂ gas concentration 0 volume%) was used, and the formation method of the Ag film 14 was the same as that of Example 1.

Comparative Example 8
An Ag film was formed in the same manner as in Comparative Example 7 except that a gas obtained by adding 9 sccm of N ₂ gas (N ₂ gas concentration: 20% by volume) to 36 sccm of Ar gas was used as the sputtering gas for forming the Ag film 14. .

Example 9, Example 10 and Comparative Examples 5 to 8 Metal oxide layer film type and film thickness, Ag film thickness, N ₂ gas concentration when forming Ag film 14, strength ratio I ₍₂₀₀₎ / I ₍₁₁₁₎ , crystallite size, reflectance, and specific resistance are shown in Table 7.

  Table 8 shows the evaluation results of chlorine durability of Example 9, Example 10 and Comparative Examples 5 to 8. The reflector was immersed in a 5% by mass NaCl aqueous solution for 1 hour and 3 hours together with the base material, and after the immersion, the state of deterioration of the Ag film surface and the state of peeling at the interface were observed.

From Table 7, the intensity ratio I ₍₂₀₀₎ / I ₍₁₁₁₎ increased with the addition of N ₂ gas. In Example 4, the Ag film was strongly oriented to the (111) plane, whereas in Example 9 formed on the PET film under the same conditions, no strong orientation to the (111) plane was observed. . The crystallite size tended to decrease with the addition of N ₂ gas, as in the case of formation on glass.

In Examples 9 and 10 and Comparative Examples 5 to 8, there is no significant difference in reflectance, and there is no influence on the reflectance due to the application of the ZnO film or the addition of N ₂ gas during the formation of the Ag film. It was. Moreover, regarding the specific resistance, like Examples 1, 2 and Comparative Examples 1 to 4, the specific resistance tends to increase with increasing N ₂ gas concentration, but all showed good values. Furthermore, in Example 4 and Example 9 which differ only in the kind of base material, it turned out that there is no big difference in a reflectance and a specific resistance, and there is no difference in the reflectance by a base material.

From Table 8, the reflectors obtained in Example 9 and Example 10 were not deteriorated on the film surface and film interface even when immersed for 3 hours. Even when a PET film was used as the substrate, glass was used. It was confirmed that excellent chlorine durability was exhibited as in the case of On the other hand, in Comparative Example 4 formed on glass with an N ₂ gas concentration of 20% by volume, no peeling of the interface was observed even when immersed in salt water for 3 hours (Table 3), but an N ₂ gas concentration of 20 on the PET film was observed. In Comparative Example 8 formed by volume%, it is essential to improve the adhesion between the base material and the Ag film because a lot of spotted film floats at the interface when immersed in salt water for 3 hours. It turns out that.

  Further, in Comparative Example 5 and Comparative Example 6, the use of the AZO film rather than the ZnO film for the metal oxide layer suppressed the degree of white turbidity when immersed in salt water. It became clear that the use was more preferable.

DESCRIPTION OF SYMBOLS 1 Target 2 Base material holder 3 Base material 4 Cathode magnet 5 Vacuum pump 6 On-off valve 7 Gas introduction pipe 8 Vacuum chamber 9 Power cord 10 DC power source 11 Backing plate 12 Transport roll 13 ZnO film 14 Ag film

Claims (5)

A reflector formed on a substrate, the reflector being doped with an element having a small atomic radius with respect to the metal oxide layer, Ag, from the side closer to the substrate as viewed from the substrate side The crystallite size calculated from the diffraction peak derived from Ag is 2 to 23 nm by X-ray diffraction measurement using CuKα rays of the reflector. Reflector. 2. The reflector according to claim 1, wherein diffraction peaks derived from the (111) plane and the (200) plane of Ag are obtained by X-ray diffraction measurement using CuKα rays of the reflector. The reflector according to claim 1 or 2, wherein the reflective layer has a thickness of 50 to 500 nm. The reflector according to any one of claims 1 to 3, wherein the metal oxide layer is made of ZnO. A visible light reflecting member comprising the reflector according to any one of claims 1 to 4 formed on a base material, and a reflection-enhancing film on the reflector.

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