JP5741325B2 - Sputtering target, manufacturing method thereof, thin film using the target, thin film sheet including the thin film, and laminated sheet - Google Patents

Description

  The present invention relates to a sputtering target suitable for forming a thin film excellent in various properties such as transparency and gas barrier properties, a method for producing the sputtering target, a thin film using the target, a thin film sheet including the thin film, and a laminated sheet. More specifically, the sputtering target used for forming a thin film suitable as a gas barrier material such as a liquid crystal display, an organic EL display, electronic paper, or a solar cell module, a method for manufacturing the same, and the target are used. The present invention relates to a thin film, a thin film sheet including the thin film, and a laminated sheet.

  Devices such as liquid crystal displays, organic EL displays, or solar cells are generally vulnerable to moisture, and their characteristics are rapidly degraded by moisture absorption. Therefore, they have high moisture resistance, that is, gas barrier properties that prevent permeation or penetration of oxygen, water vapor, and the like. It is essential to equip the parts.

  For example, in the example of a solar cell, the back sheet is provided on the back surface opposite to the light receiving surface of the solar cell module. This back sheet is typically composed of a gas barrier material having high moisture resistance and a member for protecting them as a base material.

  As a back sheet constituting such a solar cell module, for example, a solar cell module in which a moisture-proof metal foil is sandwiched by a high-strength heat-resistant weather-resistant resin and a glassy vapor-deposited film is provided on one of the moisture-proof metal foils. A sheet material for protecting the back surface is disclosed (for example, see Patent Document 1). In this sheet material, a metal foil such as an aluminum foil, a galvanized iron foil, or a tin-plated iron foil is used as a gas barrier material.

  Moreover, the solar cell which used the solar cell cover material formed by laminating | stacking and integrating a high moisture-proof film and a high weather resistance film for the back surface side protection member is disclosed (for example, refer patent document 2). The high moisture-proof film in this solar cell cover material is a coating film of inorganic oxides such as silica and alumina by a base film such as a PET film, a gas barrier material by CVD (chemical vapor deposition), PVD (reactive vapor deposition), etc. What formed the moisture-proof film | membrane which consists of is used. Also disclosed is a transparent barrier film having a base film and a barrier layer, wherein the barrier layer is an inorganic nitride thin film or an inorganic nitride oxide thin film formed by hollow cathode ion plating (for example, a patent) Reference 3). In addition, a solar cell module is disclosed in which a barrier layer that prevents permeation of one or more of water vapor, oxygen gas, decomposition products, or additives is provided on the surface of the solar cell element (for example, Patent Document 4). reference.). In this solar cell module, as the barrier layer, a resin film, a barrier resin film, an inorganic oxide vapor-deposited film, a coating film made of a polycondensate obtained by hydrolysis of a silicon compound, or two kinds thereof A composite membrane composed of the above is used.

  Moreover, the photovoltaic module provided with the barrier layer which consists of a plastic film or a plastic composite material which exhibits an inorganic oxide layer is disclosed (for example, refer patent document 5). In this inorganic oxide layer, aluminum oxide or silicon oxide is used as a coating material. Also disclosed is a back protective sheet for solar cells comprising a laminate in which an inorganic oxide thin film layer is provided on a heat- and weather-resistant plastic film, and another heat- and weather-resistant plastic film made of the same resin is laminated on the thin film layer surface. (For example, refer to Patent Document 6). In this back surface protection sheet for solar cells, an inorganic oxide thin film layer formed of either silicon oxide or aluminum oxide is used.

  In addition, a laminate in which a zinc oxide layer having ultraviolet shielding properties obtained by doping a trivalent or higher-valent metal or semiconductor on a transparent base film and a metal oxide layer having excellent gas barrier properties are sequentially laminated. Is disclosed (for example, see Patent Document 7). As the metal oxide layer of this laminate, silicon oxide, aluminum oxide, or magnesium oxide is used.

  Also, a gas barrier layer made of a metal or metal oxide is formed on at least one surface of the polymer film substrate by vapor phase growth, and a resin layer containing ultrafine particles is formed on the gas barrier layer and has an ultraviolet cutting property. A transparent gas barrier composite film material is disclosed (for example, see Patent Document 8). As the gas barrier layer of the transparent gas barrier composite film material, a single layer structure or a multilayer structure made of aluminum or a single layer structure or a multilayer structure made of at least one of aluminum oxide, silicon oxide and magnesium oxide is used. .

Japanese Utility Model Publication 2-44995 (Utility Model Registration Request and Columns 41-44) JP 2000-174296 A (Claim 1, claim 7 and paragraph [0019]) JP 2000-15737 A (Claim 1) JP 2001-217441 A (Claims 1 and 3) JP-T-2002-520820 (Claim 1 and paragraph [0019]) JP 2002-134771 A (Claims 1 and 2) Japanese Patent Laid-Open No. 7-256813 (Claims 1 and 3, paragraphs [0015] to [0016]) JP 2000-6305 A (Claims 1, 7, 8, paragraph [0020])

  However, since the sheet material for back surface protection shown in Patent Document 1 uses a metal foil such as an aluminum foil as a gas barrier material, when this sheet material is applied to a back sheet of a solar cell module, a withstand voltage is obtained. May decrease and current may leak. Further, in the sheet material using the metal foil, when the thickness of the metal foil is 20 μm or less, pinholes generated between the heat resistant weather resistant resin and the metal foil are increased, and the gas barrier property is remarkably lowered. On the other hand, if the thickness of the metal foil is increased, there will be a problem that the manufacturing cost will increase, and separation will be required as waste, or light will not be transmitted, so it should be used on the light receiving surface of the solar cell. In addition, metal foil burrs occurred around the punched hole for the power supply terminal, and there was a danger of short circuit.

  In addition, in the case of inorganic oxides such as silica and alumina used in Patent Documents 2 to 8, the film thickness must be 100 nm or more in order to obtain high gas barrier properties, and the gas barrier properties are still sufficient. I can't say that.

  The objective of this invention is providing the sputtering target suitable for forming the thin film excellent in transparency and gas-barrier property, and its manufacturing method.

  Another object of the present invention is to provide a thin film excellent in transparency and gas barrier properties, a thin film sheet comprising the thin film, and a laminated sheet.

A first aspect of the present invention is a sintered body mainly composed of zinc oxide (ZnO) and aluminum oxide (Al ₂ O ₃ ), and the relative density of the sintered body is 95% or more. The ZnO—Al ₂ O ₃ -based sputtering target is characterized in that the molar ratio of aluminum oxide to aluminum oxide is 60:40 to 80:20 .

The second aspect of the present invention, aluminum oxide and ZnO powder and Al2O3 powder having an average particle size of 0.1~5.0μm of primary particles, and zinc oxide in the sputtering target _{(ZnO) (Al 2 O 3} ) The relative density is 95% or more by mixing at a molar ratio of 60:40 to 80:20 , adding a binder, press molding, demolding, and sintering at 1000 ° C. or higher. a ZnO-Al ₂ O ₃ based sputtering target manufacturing method which is characterized in that to produce the body.

  3rd viewpoint of this invention is invention based on 2nd viewpoint, Comprising: Treatment for 1 to 10 hours at 50-150 degreeC as a preliminary | backup drying aiming at removal of an organic solvent, a water | moisture content, disappearance of a binder As a degreasing treatment for the purpose of 3), a treatment for 3 to 15 hours at 400 to 600 ° C. and a treatment for 3 to 15 hours at 1000 to 1500 ° C. as a sintering step for improving the density are performed in this order.

According to a fourth aspect of the present invention, a ZnO-Al ₂ O ₃ film is formed on a substrate surface by a sputtering method using a ZnO—Al ₂ O ₃ sputtering target based on the first aspect. This is a method for producing an Al ₂ O ₃ film.

A fifth aspect of the present invention is a ZnO—Al ₂ O ₃ -based film characterized by being formed by a manufacturing method based on the first aspect.

According to a sixth aspect of the present invention, when a ZnO—Al ₂ O ₃ film based on the fifth aspect is provided on a first base film and left for 1 hour at a temperature of 20 ° C. and a relative humidity of 50% RH. Is a thin film sheet characterized by having a water vapor permeability S of 0.3 g / m ² · day or less.

  The 7th viewpoint of this invention is a lamination sheet formed by laminating | stacking a 2nd base film through the contact bonding layer on the thin film formation side of the thin film sheet based on a 6th viewpoint.

In a first aspect the sputtering target of the present invention, a sintered body mainly composed of aluminum oxide and zinc oxide _{(ZnO) (Al 2 O 3} ), the relative density of the sintered body has 95% or more By forming a molar ratio of zinc oxide (ZnO) to aluminum oxide (Al ₂ O ₃ ) of 60:40 to 80:20 , a thin film having a gas barrier property significantly improved as compared with a conventional gas barrier material is formed. Can do. In addition, since the obtained thin film has excellent barrier properties with a single layer, it is possible to obtain high barrier properties with a small number of stacked layers, so that productivity can be improved and costs can be reduced. And by setting it as the barrier film of a single layer or few lamination layers, the total film thickness becomes thin and the crack at the time of manufacture of a barrier sheet, distortion, etc. can be reduced. When such a thin barrier film is used in a bendable solar cell, the bending resistance is improved and the durability of the solar cell is improved.

In the method for producing a sputtering target according to the second aspect of the present invention, a ZnO powder having an average primary particle size of 0.1 to 5.0 μm and an Al ₂ O ₃ powder are mixed with zinc oxide (ZnO) in the sputtering target. And mixing so that the molar ratio of aluminum oxide (Al ₂ O ₃ ) is 60:40 to 80:20 , adding a binder, press-molding, demolding, and sintering at 1000 ° C. or higher, Since a sintered body having a relative density of 95% or more is manufactured, a target capable of forming a thin film having significantly improved gas barrier properties as compared with conventional gas barrier materials can be obtained.

  In the method for producing a sputtering target according to the third aspect of the present invention, the pre-drying for the purpose of removing the organic solvent, moisture and the like is performed at 50 to 150 ° C. for 1 to 10 hours, and degreasing for the purpose of disappearance of the binder. 3 to 15 hours at 400 to 600 ° C. and 3 to 15 hours at 1000 to 1500 ° C. as a sintering process for improving the density, in this order, at the time of mixing raw material powder and forming press. Distortion can be alleviated, and the sintering process during the main sintering can easily proceed, resulting in an increase in density.

In the thin film sheet according to the sixth aspect of the present invention, the water vapor permeability when left for 1 hour under the conditions of a temperature of 20 ° C. and a relative humidity of 50% RH is as high as 0.3 g / m ² · day or less, and the time It has gas barrier properties with little deterioration over time.

  The laminated sheet of the seventh aspect of the present invention has a structure in which the second base film is laminated on the thin film forming side of the thin film sheet of the fifth aspect via an adhesive layer. Thereby, since a 2nd base film can protect a thin film, high gas barrier property can be maintained and stabilized.

It is sectional drawing which represented typically the laminated structure of the thin film sheet and laminated sheet of this invention embodiment. It is the figure which represented typically the cross-sectional structure of the conventional thin film sheet. It is the figure which represented typically the cross-sectional structure of the thin film sheet of this invention embodiment. Schematic of a sputtering apparatus.

  Next, an embodiment for carrying out the present invention will be described with reference to the drawings.

The ZnO—Al ₂ O ₃ -based sputtering target of the present invention can be suitably used for forming a thin film. A thin film formed using this sputtering target functions as a gas barrier material that prevents permeation or penetration of oxygen, water vapor, or the like.

  This sputtering target is made by mixing zinc oxide powder and aluminum oxide powder. The oxide purity of the zinc oxide powder used for the production of the sputtering target is 98% or more, preferably 99.5% or more, and the oxide purity of the aluminum oxide powder is 98% or more, preferably 99.5% or more. Here, the reason why the oxide purity in the zinc oxide powder is limited to 98% or more is that if it is less than 98%, the crystallinity deteriorates due to impurities, and as a result, the barrier characteristics are lowered. The reason why the oxide purity of the aluminum oxide powder is limited to 98% or more is that if it is less than 98%, the crystallinity deteriorates due to impurities, and as a result, the barrier characteristics are lowered. In addition, the purity of the powder in this specification is measured by a spectroscopic analysis method (inductively coupled plasma emission analyzer: ICAP-88 manufactured by Nippon Jarrell Ash). Moreover, this sputtering target consists of a polycrystal containing a zinc oxide particle and an aluminum oxide particle, and the relative density is 95% or more, Preferably it is preferable that it is 98% or more. The reason why the relative density is 95% or more is that when it is less than 95%, abnormal discharge is likely to occur during film formation, and defects are easily formed in the obtained film. The relative density in the present specification is calculated by dividing the mass measured with a mass meter by the volume measured by a vernier caliper and the volume calculated according to the volume method. In this embodiment, the structure of the sputtering target is polycrystalline, but it may be a single crystal.

Moreover, the average particle diameter of the zinc oxide particles contained in this sputtering target is 0.1 to 5.0 μm, and the average particle diameter of the aluminum oxide particles is 0.1 to 5.0 μm. The molar ratio of zinc to aluminum oxide is 60:40 to 80:20, particularly preferably 80:20. By containing zinc oxide particles and aluminum oxide particles thus refined in a predetermined ratio, a film formed using this sputtering target can exhibit a high gas barrier property.

  The technical reasons are usually (1) a sputtering target containing only zinc oxide particles and no aluminum oxide particles, (2) a sputtering target containing only aluminum oxide particles and no zinc oxide particles, (3) zinc oxide particles and When using a sputtering target that contains both aluminum oxide particles but has a low content of zinc oxide particles, or (4) a sputtering target that contains both zinc oxide particles and aluminum oxide particles but has a low content of aluminum oxide particles, As shown in FIG. 2, the oxide thin film 32 formed on the first base film 11 has a structure in which columnar crystals are gathered in parallel to the gas permeation direction. Since gas molecules such as water vapor travel along the interface of grain boundaries gathered in parallel, the thin film 32 having a structure in which the columnar crystals gather in parallel has low barrier properties. On the other hand, when a sputtering target containing fine zinc oxide particles or aluminum oxide particles in a predetermined ratio is used, an oxide formed on the first base film 11 as shown in FIG. In the thin film 12, a part of columnar crystals formed when a single composition sputtering target is used collapses to have a dense microstructure close to an amorphous state. In a dense microstructure close to the amorphous state, gas molecules such as water vapor need to move through the labyrinth for a long distance. Therefore, the barrier property is improved in the thin film 12 having a dense microstructure close to the amorphous state. Become. As described above, it is presumed that the gas barrier property is improved by forming the film in a structure suitable for preventing permeation or intrusion of moisture or the like instead of the columnar crystal. Here, the average particle size of both zinc oxide particles and aluminum oxide particles contained in the sputtering target is limited to the above range because each average particle size is less than the lower limit value, This is because agglomeration becomes remarkable and uniform mixing is hindered. If the average particle diameter of each exceeds the upper limit value, the effect of forming a pseudo solid solution that contributes to improvement of gas barrier properties cannot be obtained sufficiently. Among these, the average particle diameter of the zinc oxide particles is particularly preferably in the range of 0.1 to 5.0 μm, and the average particle diameter of the aluminum oxide particles is particularly preferably in the range of 0.1 to 5.0 μm. In the present specification, the average particle diameter is measured once by using Nikkiso Co., Ltd. (FRA type) according to the laser diffraction / scattering method (microtrack method) and using sodium hexametaphosphate as a dispersant. Values obtained by averaging three times with a time of 30 seconds are averaged.

  In addition, the molar ratio of zinc oxide and aluminum oxide contained in the sputtering target is limited to the above range when the molar ratio of zinc oxide is less than 50 or the molar ratio of aluminum oxide is less than 5, the zinc oxide particles or aluminum oxide. Since the content ratio of particles becomes too small and approaches a single composition, it becomes easier to take a structure in which columnar crystals are assembled in parallel to the gas permeation direction, so a thin film with a dense microstructure is formed. It is not possible.

Since the ZnO—Al ₂ O ₃ film formed using the sputtering target of the present invention is excellent in barrier properties in a single layer, it is possible to obtain high barrier properties with a small number of layers, and thus productivity is improved. The cost can be reduced. And by making it a barrier film of a single layer or a small number of laminated layers, the total film thickness becomes thin, and it is possible to reduce cracks, distortion, etc. during the manufacture of the barrier sheet. When such a thin barrier film is used in a bendable solar cell, the bending resistance is improved and the durability of the solar cell is improved. Moreover, since it has a high gas barrier property, as a gas barrier material such as a liquid crystal display, an organic EL display, an organic EL display for illumination, or an electronic paper, in addition to the use of a gas barrier material such as a moisture-proof film constituting a back sheet of a solar cell. Can also be suitably used. In addition, since this ZnO—Al ₂ O ₃ based film has transparency with a transmittance of about 85 to 95%, a member that requires high gas barrier properties and also requires light transmission, such as solar It is also suitable as a gas barrier material used on the light receiving surface side of the battery, the image viewing side of the display, and the like.

  Next, the production method of the sputtering target of the present invention will be described as a representative case of producing it by a sintering method. First, a high-purity powder having a purity of 98% or more as zinc oxide powder, a high-purity powder having a purity of 98% or more as aluminum oxide powder, a binder, and an organic solvent are mixed, and the concentration is 30 to 75% by mass. Prepare a slurry. Preferably, a slurry of 40 to 65% by mass is prepared. The zinc oxide powder and the aluminum oxide powder are mixed and adjusted so that the molar ratio of zinc oxide and aluminum oxide in the sputtering target after production satisfies the above range. The reason why the concentration of the slurry is limited to 30 to 75% by mass is that when the content exceeds 75% by mass, the slurry is non-aqueous, so there is a problem that stable mixed granulation is difficult. This is because a dense sintered body having the above cannot be obtained. Moreover, the average particle diameter of the zinc oxide powder to be used and the average particle diameter of the aluminum oxide powder are adjusted to the above-mentioned ranges of the average particle diameter of the zinc oxide powder and the average particle diameter of the aluminum oxide particles contained in the sputtering target after production. For this reason, the zinc oxide powder is preferably in the range of 0.1 to 5.0 μm, and the aluminum oxide powder is preferably in the range of 0.1 to 5.0 μm.

  It is preferable to use polyethylene glycol or polyvinyl butyral as the binder, and ethanol or propanol as the organic solvent. The binder is preferably added in an amount of 0.2 to 5.0% by mass.

The wet mixing of the high purity powder, the binder, and the organic solvent, particularly the wet mixing of the high purity powder and the organic solvent that is the dispersion medium is performed by a wet ball mill or a stirring mill. In the wet ball mill, when ZrO ₂ balls are used, wet mixing is performed for 8 to 24 hours, preferably 20 to 24 hours, using a large number of ZrO ₂ balls having a diameter of 5 to 10 mm. The reason why the diameter of the ZrO ₂ balls is limited to 5 to 10 mm is that mixing is insufficient when the diameter is less than 5 mm, and there is a problem that impurities increase when the diameter exceeds 10 mm. The reason why the mixing time is as long as 24 hours is that the generation of impurities is small even if the mixing is continued for a long time.

In the stirring mill, wet mixing is performed for 0.5 to 1 hour using a ZrO ₂ ball having a diameter of 1 to 3 mm. The reason why the diameter of the ZrO ₂ balls is limited to 1 to 3 mm is that the mixing is insufficient when the diameter is less than 1 mm, and the impurity increases when the diameter exceeds 3 mm. Also, the mixing time is as short as 1 hour at maximum, because if the time exceeds 1 hour, not only the mixing of the raw materials but also the balls themselves are worn out, which causes the generation of impurities and can be sufficiently mixed in 1 hour. .

Next, the slurry is spray-dried to obtain a mixed granulated powder having an average particle size of 50 to 250 μm, preferably 50 to 200 μm. This granulated powder is put into a predetermined mold and molded at a predetermined pressure. The spray drying is preferably performed using a spray dryer, and the predetermined mold is a uniaxial press apparatus or a cold isostatic press (CIP) molding apparatus. In uniaxial pressing apparatus, granulated powder 750~2000kg / cm ² (73.55~196.1MPa), preferably uniaxial pressing at a pressure of 1000~1500kg / cm ² (98.1~147.1MPa) In the CIP molding apparatus, the granulated powder is CIP molded at a pressure of 1000 to 3000 kg / cm ² (98.1 to 294.2 MPa), preferably 1500 to 2000 kg / cm ² (147.1 to 196.1 MPa). The reason why the pressure is limited to the above range is to increase the density of the molded body, prevent deformation after sintering, and eliminate the need for post-processing.

  Further, after demolding, the compact is sintered at a predetermined temperature. Sintering is carried out at a temperature of 1000 ° C. or higher, preferably 1200 to 1400 ° C. for 1 to 10 hours, preferably 2 to 5 hours in the atmosphere, inert gas, vacuum or reducing gas atmosphere. Thereby, a sputtering target having a relative density of 95% or more is obtained. The above sintering is performed at atmospheric pressure, but when performing pressure sintering such as hot press (HP) sintering or hot isostatic press (HIP) sintering, an inert gas, It is preferable to carry out at a temperature of 1000 ° C. or higher for 1 to 5 hours in a vacuum or a reducing gas atmosphere.

  In addition, it is preferable to pre-dry and degrease a molded object before the said sintering. As a pre-drying for the purpose of removing organic solvents and moisture, the treatment is performed at 50 to 150 ° C. for 1 to 10 hours, and as the degreasing treatment for the purpose of burning out the binder, the treatment is carried out at 400 to 600 ° C. for 3 to 15 hours. It is good to perform the process for 3 to 15 hours at 1000 degreeC-1500 degreeC as a sintering process which performs and improves a density. By performing these pre-drying and degreasing treatments, the strain applied during the mixing and molding press of the raw material powder can be alleviated, and the sintering process during the main sintering can easily proceed, resulting in an increase in density. .

Subsequently, the thin film sheet and the laminated sheet of the present invention will be described together with the manufacturing method thereof. As shown in FIG. 1, a thin film sheet 10 of the present invention has a first base film 11 and a ZnO—Al ₂ O ₃ film 12 of the present invention, preferably formed using the above sputtering target. And the lamination sheet 20 of this invention has the 2nd base film 14 adhere | attached through the contact bonding layer 13 on the thin film formation side of this thin film sheet 10 of the said invention.

  It is preferable that the first base film 11 and the second base film 14 have mechanical strength, weather resistance, and the like that can withstand a long-term high temperature and high humidity environment test. For example, resin films such as polyethylene terephthalate (PET), polycarbonate, polymethyl methacrylate, polyacrylate, polyethylene naphthalate (PEN), polyarylate, polyether sulfone, triacetyl cellulose (TAC), and cyclic olefin (co) polymer Is mentioned. These resin films may contain a flame retardant, an antioxidant, an ultraviolet absorber, an antistatic agent, and the like as necessary. The thickness of the 1st base film 11 and the 2nd base film 14 becomes like this. Preferably it is 5-300 micrometers, More preferably, it is 10-150 micrometers.

On the first base film 11, preferably by using the sputtering target of the present invention described above, ZnO-Al ₂ O ₃ based film 12 as a gas barrier material is formed. Among these, the thickness of the ZnO—Al ₂ O ₃ film 12 is particularly preferably in the range of 20 to 100 nm.

The method for forming a ZnO—Al ₂ O ₃ film of the present invention uses a ZnO—Al ₂ O ₃ film on the surface of a substrate such as the first base film, for example, by sputtering using the obtained sputtering target. Is formed. A usable substrate may be a conventionally known substrate and is not particularly limited, but a resin substrate such as PET is preferable.

  Sputtering is a kind of physical vapor deposition (PVD method). When accelerated particles (or ions) collide with a solid surface, sputtering obtains a part of the momentum of the particle and obtains a solid surface. A phenomenon in which nearby atoms are knocked out into space. Film formation is performed using this sputtering phenomenon. The sputtering method includes a direct current sputtering method in which a direct current electric field is applied and a high frequency sputtering method in which a high frequency electric field is applied. Moreover, it classify | categorizes into 2 pole type, 4 pole type sputtering method etc. also by the number of electrodes.

  FIG. 4 shows a general sputtering apparatus 40. The vacuum vessel 41 has a gas inlet 42 and a vacuum exhaust port 43, and flat electrodes 44 and 46 are provided inside the vessel 41 in parallel. The electrodes 44 and 46 are connected to a DC power source or a high frequency power source 47 outside the container, and are grounded. A target material 48 can be set on the cathode 44, and the anode 46 has a structure also serving as a substrate holder so that a substrate 49 can be set.

When forming a ZnO—Al ₂ O ₃ based film using the sputtering apparatus having such a configuration, first, the sputtering target 48 of the present invention is set on the cathode 44 and the substrate 49 is set on the anode 46, respectively. Next, after evacuating the inside of the vacuum vessel 41 to 5 × 10 ⁻⁴ Pa or less with a vacuum exhaust device, Ar gas 51 and oxygen gas are added so that the atmosphere inside the vacuum vessel 41 becomes about 0.3 to 1.0 Pa. It introduces from the gas inlet 42. The substrate 49 is not heated or heated to a temperature of 150 ° C. or lower. Next, when a direct current or a high frequency electric field is applied to the electrodes 44 and 46, glow discharge is generated in the Ar gas 51 introduced into the vacuum vessel 41, and Ar ions 52 (indicated as + in FIG. 4) are generated. The Ar ions 52 generated by the glow discharge are accelerated by being attracted by the negative voltage of the cathode 44, hit the target material 48 installed on the cathode 44, and atoms of each metal element and oxygen of the target material ejected by the impact. Evaporates by sputtering. The atoms (denoted as M in FIG. 4) of each metal element 53 evaporated by sputtering are combined with oxygen atoms evaporated by sputtering and oxygen gas introduced from the gas inlet 42 to reach the substrate 49 held by the anode 46. and this is ZnO-Al ₂ O ₃ based film is formed by being deposited.

Although not shown in FIG. 1, acrylic polyol, isocyanate, and silane coupling are used as necessary to improve the adhesion strength with the ZnO—Al ₂ O ₃ film 12 on the first base film 11. A primer coating layer made of an agent may be provided, or a surface treatment using plasma or the like may be performed before the vapor deposition step.

On the other hand, when the surface of the formed ZnO—Al ₂ O ₃ film 12 is exposed, if the surface of the film is scratched or rubbed when the sheet is handled, the gas barrier property is greatly affected. Therefore, it is preferable to provide a gas barrier film (not shown) for protecting the surface of the ZnO—Al ₂ O ₃ film 12 on the ZnO—Al ₂ O ₃ film 12. This gas barrier coating is obtained by mixing, for example, a solution obtained by mixing a silicon compound having an alkoxyl group, a titanium compound, a zirconia compound, a tin compound or a hydrolyzate thereof with a water-soluble polymer having a hydroxyl group into a ZnO—Al ₂ O ₃ film. After applying to 12 surfaces, it can be formed by heating and drying. This gas barrier film not only functions as a protective layer for the ZnO—Al ₂ O ₃ film 12 but also has an effect of improving the gas barrier property.

The thin film sheet 10 of the present invention thus formed is, for example, left for 1 hour under the conditions of a temperature of 20 ° C. and a relative humidity of 50% RH, and then measured for water vapor transmission measured under the conditions of a temperature of 40 ° C. and a relative humidity of 90% RH. The degree is 0.3 g / m ² · day or less.

Furthermore, in the laminated sheet 20 of the present invention, an adhesive layer 13 is formed on the thin film forming side of the thin film sheet 10 of the present invention, that is, on the ZnO—Al ₂ O ₃ film 12 or on the gas barrier film. The layer 13 functions as an adhesive for bonding the first base film 11 and the second base film 14 on which the ZnO—Al ₂ O ₃ based film 12 is formed. Therefore, it is necessary that the adhesive strength does not deteriorate over a long period of time, does not cause delamination, and does not yellow, such as polyurethane, polyester, polyester-polyurethane, polycarbonate, Examples thereof include an epoxy-amine-based adhesive and a hot-melt adhesive. The adhesive layer 13 can be laminated by a known method such as a dry lamination method.

The laminated sheet 20 is completed by bonding and bonding the second base film 14 on the adhesive layer 13. As shown in FIG. 1, the ZnO—Al ₂ O ₃ film 12 and the adhesive layer 13 are not necessarily limited to those laminated one by one, and are bonded to the ZnO—Al ₂ O ₃ film 12. The layers 13 may be alternated, or may be 2 to 10 layers in which other members such as the ZnO—Al ₂ O ₃ film 12, the gas barrier coating, and the adhesive layer 13 are alternately or randomly stacked. Thereby, gas barrier property and a weather resistance can be improved further.

  This laminated sheet 20 can be suitably used for applications such as a back sheet of a solar cell module, a liquid crystal display, an organic EL display, an organic EL display for illumination, or electronic paper.

Next, examples and reference examples of the present invention will be described in detail together with comparative examples. Examples 1 and 4 shown below are reference examples, not examples.

<Example 1>
First, a high-purity ZnO powder having an average particle diameter of 0.8 μm and a purity of 99.8% is used as a binder, and a high-purity Al ₂ O ₃ powder having an average particle diameter of 1.5 μm and a purity of 99.8% is used as a binder. The resin was prepared with ethanol and acetone as organic solvents.

Next, ZnO powder, Al ₂ O ₃ powder, binder and organic solvent were mixed at a predetermined ratio by wet mixing with a ball mill to prepare a slurry having a concentration of 40% by mass. The mixing amount of the ZnO powder and the Al ₂ O ₃ powder was adjusted so that ZnO contained in the formed sputtering target was 50 mol% and Al ₂ O ₃ was 50 mol%.

  Next, the prepared slurry was spray-dried using a spray dryer to obtain a mixed granulated powder having an average particle size of 200 μm, and the granulated powder was put into a predetermined mold and press-molded by a uniaxial press machine. After demolding, the obtained molded body was sintered in an air atmosphere at a temperature of 1300 ° C. for 5 hours to obtain a sputtering target.

<Example 2>
The mixture amount of ZnO powder and Al ₂ O ₃ powder was the same as in Example 1 except that the ZnO contained in the formed sputtering target was adjusted to 61 mol% and Al ₂ O ₃ to 39 mol%. A sputtering target was obtained.

<Example 3>
The mixed amount of ZnO powder and Al ₂ O ₃ powder was the same as in Example 1 except that the amount of ZnO contained in the formed sputtering target was adjusted to 80 mol% and Al ₂ O ₃ was 20 mol%. A sputtering target was obtained.

<Example 4>
The mixed amount of the ZnO powder and the Al ₂ O ₃ powder was the same as in Example 1 except that the ZnO contained in the formed sputtering target was adjusted to 95 mol% and Al ₂ O ₃ was 5 mol%. A sputtering target was obtained.

<Examples 5-9>
The mixed amount of ZnO powder and Al ₂ O ₃ powder was the same as in Example 1 except that the amount of ZnO contained in the formed sputtering target was adjusted to 80 mol% and Al ₂ O ₃ was 20 mol%. A sputtering target was obtained.

<Example 10>
A high-purity ZnO powder having an average particle diameter of 0.1 μm and a purity of 99.8% and a high-purity Al ₂ O ₃ powder having an average particle diameter of 0.1 μm and a purity of 99.8% are used. The sputtering target was adjusted in the same manner as in Example 1 except that the mixing amount of ₂ O ₃ powder was adjusted so that ZnO contained in the formed sputtering target was 80 mol% and Al ₂ O ₃ was 20 mol%. Obtained.

<Example 11>
A high-purity ZnO powder having an average particle diameter of 5.0 μm and a purity of 99.8% and a high-purity Al ₂ O ₃ powder having an average particle diameter of 5.0 μm and a purity of 99.8% were used. The sputtering target was adjusted in the same manner as in Example 1 except that the mixing amount of ₂ O ₃ powder was adjusted so that ZnO contained in the formed sputtering target was 80 mol% and Al ₂ O ₃ was 20 mol%. Obtained.

<Comparative Example 1>
A sputtering target was obtained in the same manner as in Example 1 except that adjustment was performed without mixing the Al ₂ O ₃ powder.

<Comparative Example 2>
The mixed amount of the ZnO powder and the Al ₂ O ₃ powder was the same as that of Example 1 except that the ZnO contained in the formed sputtering target was adjusted to 98 mol% and Al ₂ O ₃ was 2 mol%. A sputtering target was obtained.

<Comparative Example 3>
The mixed amount of ZnO powder and Al ₂ O ₃ powder was the same as in Example 1 except that the ZnO contained in the formed sputtering target was adjusted to 40 mol% and Al ₂ O ₃ was 60 mol%. A sputtering target was obtained.

<Comparative Example 4>
A sputtering target was obtained in the same manner as in Example 1 except that the ZnO powder was adjusted without mixing.

<Comparison test>
Using the sputtering targets obtained in Examples 1 to 11 and Comparative Examples 1 to 4, a thin film having a thickness of 100 nm was formed on a PET film having a thickness of 75 μm by vapor deposition by RF sputtering. Formed. As for the sputtering conditions, the deposition rate is 1 nm / sec, and the substrate temperature and oxygen gas partial pressure are as shown in Table 1 below. About these thin film sheets, water vapor permeability was measured and gas barrier property was evaluated. Moreover, about these thin film sheets, the light transmittance was measured and transparency was evaluated. These results are shown in Table 1 below.

  (1) Gas barrier property: After the thin film sheet is left in a clean room set at a temperature of 20 ° C. and a relative humidity of 50% RH for 1 hour, a water vapor transmission rate measuring device (model name: PERMATRAN-W type 3 / 33), the water vapor transmission rate was measured under the conditions of a temperature of 40 ° C. and a relative humidity of 90% RH.

  (2) Light transmittance: The light transmittance at a wavelength of 380 to 780 nm was measured for the thin film sheet using a spectrophotometer (model name: U-4000) manufactured by Hitachi, Ltd.

表１から明らかなように、実施例１〜１１及び比較例１〜４を比較すると、実施例１〜１１では、光透過率は高く、また、室温で１時間放置した後の水蒸気透過度は、０．２８ｇ／ｍ²・ｄａｙ以下と優れたバリア性を示した。また、ＺｎＯとＡｌ₂Ｏ₃のモル比が８０：２０に近づくほど優れた水蒸気透過率を示すことが確認された。

As is apparent from Table 1, when Examples 1 to 11 and Comparative Examples 1 to 4 are compared, in Examples 1 to 11, the light transmittance is high, and the water vapor permeability after standing at room temperature for 1 hour is Excellent barrier properties of 0.28 g / m ² · day or less were exhibited. Furthermore, to exhibit more excellent water vapor permeability molar ratio of ZnO and Al ₂ O ₃ approaches the 80:20 was confirmed.

On the other hand, formed using a thin film sheet of Comparative Examples 1 and 4 formed using a sputtering target having a single composition and a sputtering target having a ZnO content of 40 mol% or an Al ₂ O ₃ content of 2 mol%. In the thin film sheets of Comparative Examples 2 and 3, the light transmittance was high, but the water vapor permeability was high.

  Furthermore, paying attention to the film formation conditions, the barrier characteristics improved as the film formation substrate temperature increased, and the light transmittance tended to increase as the oxygen partial pressure increased.

10 thin film sheet 11 first base film 12 ZnO-Al ₂ O ₃ based film 13 adhesive layer 14 the second base film 20 laminated sheet

Claims (7)

It consists of a sintered body mainly composed of zinc oxide (ZnO) and aluminum oxide (Al ₂ O ₃ ), the relative density of the sintered body is 95% or more, and the molar ratio of the zinc oxide to the aluminum oxide ZnO—Al ₂ O ₃ -based sputtering target, characterized in that is 60:40 to 80:20 . A ZnO powder having an average primary particle size of 0.1 to 5.0 μm and an Al ₂ O ₃ powder, the molar ratio of the zinc oxide (ZnO) and the aluminum oxide (Al ₂ O ₃ ) in the sputtering target is 60:40 to 80:20 are mixed, a binder is added, pressure-molded, demolded, and sintered at 1000 ° C. or higher to produce a sintered body having a relative density of 95% or higher. ZnO-Al ₂ O ₃ based sputtering target manufacturing method which is characterized in that. Treatment at 50 to 150 ° C. for 1 to 10 hours as preliminary drying for the purpose of removing organic solvents and moisture, etc., treatment at 400 to 600 ° C. for 3 to 15 hours as a degreasing treatment for the purpose of binder disappearance, and density claim ₂ ZnO-Al 2 O ₃ based sputtering target manufacturing method according to the process of 3-15 hours at 1000 to 1500 ° C. as a sintering process performed in this order to improve. Method for producing a ZnO-Al ₂ O ₃ based film and forming a ZnO-Al ₂ O ₃ based film on the substrate surface by a sputtering method using a ZnO-Al ₂ O ₃ based sputtering target according to claim 1, wherein . A ZnO—Al ₂ O ₃ film formed by the manufacturing method according to claim 4. The ZnO—Al ₂ O ₃ based film according to claim 5 is provided on a first base film,
A thin film sheet having a water vapor permeability S of 0.3 g / m ² · day or less when left for 1 hour under conditions of a temperature of 20 ° C. and a relative humidity of 50% RH.   The laminated sheet formed by laminating | stacking a 2nd base film through the contact bonding layer on the thin film formation side of the thin film sheet of Claim 6.

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