JP2013073851A - Transparent conductive laminate and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent conductive laminate having a low resistance transparent conductive film in which lamination can be carried out in-line by using a sputtering target of different composition, and crystallinity can be provided by short time heating treatment, and to provide a manufacturing method therefor.SOLUTION: The transparent conductive film is formed of a first transparent conductive film 3a composed of an indium/tin composite oxide containing In, Sn, O as main components where the content of Sn is 1-4 wt.%, and a second transparent conductive film 3b composed of an indium/tin composite oxide similarly containing In, Sn, O as main components where the content of Sn is 4-10 wt%. Thickness of the first and second transparent conductive films is 10-30 nm, and the total thickness of both transparent conductive films is 20-40 nm. The first and second transparent conductive films can be crystallized by heating treatment under such conditions that the heating temperature in vacuum is 120-200°C, and the heating time is 1-30 min.

Description

  The present invention relates to a transparent conductive laminate and a method for producing the transparent conductive laminate.

  In recent years, transparent touch panels that allow input by simply touching a display screen with a finger or pressing the display screen with a pen have become widespread. A transparent conductive substrate used as an electrode of this type of touch panel basically has a structure in which a conductive film is laminated on glass or a polymer film. In recent years, transparent conductive films using polymer films such as polyethylene terephthalate have been used because they have advantages such as excellent flexibility and workability and light weight.

  There are various types of touch panel methods such as a capacitance method and an optical method. Among them, touch panels using a transparent conductive film include a resistance film type that specifies a touch position by touching upper and lower electrodes and a capacitance type that senses a change in capacitance. Since this type of touch panel is used on the front surface of a display such as a portable terminal device and a portable game machine, it needs transmission / reflection characteristics that do not impair the display of the display.

  In particular, the market for transparent conductive films for touch panels mounted on smartphones and slate PCs is growing. In this case, the electrostatic capacity method is mainly adopted. Moreover, in the transparent conductive film used for the electrostatic capacity method, since it is necessary to pattern the conductive film, it is necessary to devise such that the presence or absence of the conductive film is not conspicuous, and compared with the resistance film type A low resistance is required.

  At present, an ITO film is mainly used as a conductive film because it has good conductivity and good translucency in the visible light wavelength region. In order to obtain a low-resistance conductive film, it can be dealt with by increasing the film thickness of the ITO film itself, but there is also a problem in optical characteristics such as a decrease in transmittance due to the increase in film thickness. In the following, in order to achieve both the resistance value and the optical characteristics, it is necessary that the ITO film is crystallized.

JP 2006-244771 A JP 2008-71531 A Japanese Patent Application Laid-Open No. 2004-149884

However, in the methods of Patent Documents 1 to 3 and the like, transparent conductive films having different SnO ₂ contents are stacked and crystallized. However, heating for a long time has to be performed for crystallization.

The present invention has been made in view of the problems of the prior art. The object of the present invention is to laminate transparent conductive films having different contents of Sn, and to form crystals even if the O ₂ concentration of the film forming atmosphere gas is low. An object of the present invention is to provide a low-resistance transparent conductive laminate that is easy to be converted and can obtain crystallinity by heating in a short time in a vacuum, and a method for producing the same.

  In order to solve the above problems, the invention described in claim 1 is a transparent conductive laminate in which a transparent conductive film is formed on at least one surface of a transparent substrate, and the transparent conductive film includes In, Sn, and O. A first transparent conductive film made of an indium-tin composite oxide having a Sn content of 1 wt% to 4 wt%, and a Sn content of In, Sn, O Of the first transparent conductive film and the second transparent conductive film are each 10 nm or more and 30 nm in thickness. The total thickness of both transparent conductive films is 20 nm to 40 nm, the heating temperature is 120 ° C. to 200 ° C. in vacuum, and the heating time is 1 minute to 30 minutes. Heat treatment at conditions Both said first transparent conductive film of the second transparent conductive film in Rukoto characterized by crystallization.

  The invention according to claim 2 is characterized in that in the transparent conductive laminate according to claim 1, a metal or an inorganic compound is provided between the transparent substrate and the first transparent conductive film. .

  The invention according to claim 3 is the transparent conductive laminate according to claim 1 or 2, wherein a hard coat layer in contact with the transparent substrate is provided on one surface or both surfaces of the transparent substrate. And the thickness of the hard coat layer is 1 μm or more and 8 μm or less.

In addition, the invention according to claim 4 is a method in which the first transparent conductive film and the second transparent conductive film are continuously conveyed in vacuum using a sputtering method while the transparent base material is conveyed in a roll-to-roll manner. The formed film forming atmosphere gas uses Ar and O ₂ , and the volume ratio of O ₂ is 0.1 or more and 5% or less. This is a method for producing a transparent conductive laminate.

  Moreover, invention of Claim 5 is a manufacturing method of the transparent conductive laminated body as described in any one of Claims 1-3 by which the said heat processing are performed by a roll-to-roll system. .

  According to the present invention, a transparent conductive film can be laminated in-line using sputtering targets having different compositions, and the transparent conductive film can have crystallinity by a short heat treatment, which is suitable for a capacitive touch panel. In addition, a transparent conductive laminate having a low-resistance transparent conductive film can be produced.

It is sectional drawing of the transparent conductive laminated body which concerns on one Embodiment of this invention. It is sectional drawing of the transparent conductive laminated body which concerns on other embodiment of this invention. It is sectional drawing of the transparent conductive laminated body which concerns on other embodiment of this invention. It is a schematic explanatory drawing of the heat processing apparatus of a transparent conductive laminated body. The figure which shows the analysis result of the transparent conductive laminated body obtained in Example 1 and 2. FIG. The figure which shows the analysis result after the heating of the transparent conductive laminated body obtained in Example 1 and 2. FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, and modifications such as design changes can be added based on the knowledge of those skilled in the art. Forms are also included within the scope of the present invention.

  FIG. 1 is a cross-sectional view of a transparent conductive laminate according to an embodiment of the present invention. In FIG. 1, 1 has shown the transparent conductive laminated body. This transparent conductive laminate 1 has a laminated structure in which a first transparent conductive film 3a is provided on one surface of a transparent substrate 2, and a second transparent conductive film 3b is provided on the first transparent conductive film 3a. Is.

  FIG. 2 is a cross-sectional view of a transparent conductive laminate according to another embodiment of the present invention. This transparent conductive laminate has an adhesion layer 4 between one surface of the transparent substrate 2 of the transparent conductive laminate 1 shown in FIG. 1 and the first transparent conductive film 3a provided on this surface. It has a configuration provided.

  3 (a) and 3 (b) are cross-sectional views showing a transparent conductive laminate according to still another embodiment of the present invention. These are the first transparent conductive film 3a provided on one surface of the transparent base material 2 of the transparent conductive laminate 1 shown in FIG. 1 or the adhesion layer 4 shown in FIG. The hard coat layer 5 is provided between them. Further, as shown in FIG. 2B, the hard coat layer 5 may be provided on the surface of the transparent substrate 2 on which the first transparent conductive film 3a and the adhesion layer 4 are not provided.

  FIG. 4 is an explanatory view schematically showing the configuration of the heat treatment apparatus 7 for heat-treating the transparent conductive laminate according to the present invention. The heat treatment apparatus 7 is configured to convey the transparent conductive laminate 1 by a roll-to-roll method, and a heater 6 is installed in the middle of the path along which the transparent conductive laminate 1 is conveyed. The transparent conductive laminate 1 conveyed by the heater 6 can be heated at an arbitrary temperature. Further, the pressure in the apparatus can be adjusted from atmospheric pressure to 0.1 Pa by a vacuum pump (not shown).

  The transparent substrate 2 used in the present invention is a plastic film made of a resin. The plastic film is not particularly limited as long as it has sufficient strength in the film-forming process and the post-process and has good surface smoothness. For example, polyethylene terephthalate film, polybutylene terephthalate film, polyethylene Naphthalate film, polycarbonate film, polyethersulfone film, polysulfone film, polyarylate film, cyclic polyolefin film, polyimide film and the like can be mentioned. The thickness is about 10 μm or more and 200 μm or less in consideration of the thinning of the member and the flexibility of the base material.

  As the material contained in the transparent substrate 2, various known additives and stabilizers such as an antistatic agent, a plasticizer, a lubricant, and an easy adhesive may be used. In order to improve the adhesion with each layer, corona treatment, low temperature plasma treatment, ion bombardment treatment, chemical treatment, etc. may be performed as pretreatment.

  The hard coat layer 5 in the present invention is provided to give the transparent conductive laminate 1 mechanical strength. For example, the resin used as the hard coat layer 5 is not particularly limited, but a resin having transparency, appropriate hardness, and mechanical strength is preferable. Specifically, a photocurable resin such as a monomer or a crosslinkable oligomer having a tri- or higher functional acrylate that can be expected to be three-dimensionally crosslinked as a main component is preferable.

  Examples of the tri- or higher functional acrylate monomer include trimethylolpropane triacrylate, isocyanuric acid EO-modified triacrylate, pentaerythritol triacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexa Preferred are acrylate, ditrimethylolpropane tetraacrylate, pentaerythritol tetraacrylate, and polyester acrylate. Particularly preferred are isocyanuric acid EO-modified triacrylates and polyester acrylates. These may be used alone or in combination of two or more. In addition to these tri- or higher functional acrylates, so-called acrylic resins such as epoxy acrylate, urethane acrylate, and polyol acrylate can be used in combination.

  As the crosslinkable oligomer, acrylic oligomers such as polyester (meth) acrylate, polyether (meth) acrylate, polyurethane (meth) acrylate, epoxy (meth) acrylate, and silicone (meth) acrylate are preferable. Specific examples include polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, bisphenol A type epoxy acrylate, polyurethane diacrylate, and cresol novolac type epoxy (meth) acrylate.

  The hard coat layer 5 may further contain additives such as particles and a photopolymerization initiator.

  Examples of the particles to be added include organic or inorganic particles, but it is preferable to use organic particles in consideration of transparency. Examples of the organic particles include particles made of acrylic resin, polystyrene resin, polyester resin, polyolefin resin, polyamide resin, polycarbonate resin, polyurethane resin, silicone resin, and fluorine resin.

  The average particle size of the particles varies depending on the thickness of the hard coat layer 5, but for reasons of appearance such as haze, the lower limit is 2 μm or more, more preferably 5 μm or more, and the upper limit is 30 μm or less, preferably 15 μm or less. Use things. Further, for the same reason, the particle content is preferably 0.5% by weight or more and 5% by weight or less based on the resin.

  In addition, when a photopolymerization initiator is added to the hard coat layer 5, benzoin such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzylmethyl ketal, and its alkyl ether are used as radical generating photopolymerization initiators. Acetophenones such as acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, anthraquinones such as methylanthraquinone, 2-ethylanthraquinone, 2-amylanthraquinone, thioxanthone, 2,4- Thioxanthones such as diethylthioxanthone, 2,4-diisopropylthioxanthone, ketals such as acetophenone dimethyl ketal and benzyl dimethyl ketal, Non, and the like 4,4-bis benzophenones such as methylamino benzophenone and azo compounds. These can be used alone or as a mixture of two or more thereof, and further, tertiary amines such as triethanolamine and methyldiethanolamine, benzoic acid derivatives such as 2-dimethylaminoethylbenzoic acid and ethyl 4-dimethylaminobenzoate, etc. It can be used in combination with a photoinitiator aid or the like.

  The addition amount of the photopolymerization initiator is 0.1% by weight or more and 5% by weight or less, preferably 0.5% by weight or more and 3% by weight or less with respect to the main component resin. If it is less than the lower limit, curing of the resin layer becomes insufficient, which is not preferable. Moreover, when exceeding an upper limit, since yellowing of a resin layer will be produced or a weather resistance will fall, it is unpreferable. The light used to cure the photocurable resin is ultraviolet rays, electron beams, or gamma rays, and in the case of electron beams or gamma rays, it is not always necessary to contain a photopolymerization initiator or a photoinitiator aid. As these radiation sources, high-pressure mercury lamps, xenon lamps, metal halide lamps, accelerated electrons, and the like can be used.

  The thickness of the hard coat layer 5 is not particularly limited, but is preferably in the range of 0.5 μm or more and 15 μm or less. Moreover, it is more preferable that the refractive index is the same as or close to that of the transparent substrate 2, and it is preferably about 1.45 or more and 1.75 or less.

  The hard coat layer 5 is formed by dissolving a resin as a main component in a solvent, a die coater, a curtain flow coater, a roll coater, a reverse roll coater, a gravure coater, a knife coater, a bar coater, a spin coater, and a micro gravure coater. It forms by the well-known coating methods, such as.

  The solvent is not particularly limited as long as it dissolves the main component resin and the like. Specifically, as a solvent, ethanol, isopropyl alcohol, isobutyl alcohol, benzene, toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, n-butyl acetate, isoamyl acetate, ethyl lactate, methyl cellosolve, ethyl cellosolve, Examples include butyl cellosolve, methyl cellosolve acetate, and propylene glycol monomethyl ether acetate. These solvents may be used alone or in combination of two or more.

  As a material for forming the adhesion layer 4, a metal or an inorganic compound such as an oxide, sulfide, or fluoride thereof can be used. Practically, silicon oxide, aluminum oxide, etc. are particularly preferably used.

  The first transparent conductive film 3a and the second transparent conductive film 3b are mainly composed of In, Sn, and O, mixed oxides thereof, and, if necessary, Al, Zr, Ga, Si, W, etc. Additives can be included. Various materials can be used depending on the purpose and application, and are not particularly limited. At present, the most reliable and proven material is indium tin oxide (ITO).

  As a manufacturing method of the adhesion layer 4, the first transparent conductive film 3a, and the second transparent conductive film 3b, there is a sputtering method in which the process is stable and the thin film becomes dense in order to form a thin film having a uniform film quality over a large area. It is used and laminated on the transparent substrate 2 using a mixed gas of an inert gas and oxygen as a film forming atmosphere gas.

  It is preferable that the volume ratio of oxygen in the deposition atmosphere gas used for forming the first transparent conductive film and the second transparent conductive film is 0.1% or more and 5% or less. In particular, in order to sufficiently crystallize the first transparent conductive film that is easily affected by the reducing gas component from the substrate, it is preferable to supply a large amount of oxygen, and the volume ratio of oxygen is 1.5% to 5%. The following is more preferable. When the volume ratio of oxygen is less than 0.1%, the resistance value increases rapidly after heating and the transmittance decreases. If it exceeds 5%, the resistance value increases rapidly after heating, and a transparent conductive laminate having the required resistance value cannot be obtained.

  However, when indium tin oxide (ITO), which is a general transparent conductive film, is used as the first transparent conductive film 3a and the second transparent conductive film 3b, the content ratio of tin oxide doped in indium oxide is required for the device. Select an arbitrary ratio according to the specifications. The sputtering target material used for crystallizing the transparent conductive film preferably has a tin oxide content of 1 wt% or more and 4 wt% or less in the first transparent conductive film. In the second transparent conductive film, the content ratio of tin oxide is preferably more than 4% by weight and 10% by weight or less. In the case of the present invention, considering the control of crystallinity and the resistance value, the second transparent conductive film is particularly preferably 5% by weight or more and 7% by weight or less.

  The film thicknesses of the first transparent conductive film 3a and the second transparent conductive film 3b are both 10 nm or more and 30 nm or less, and the total thickness of both transparent conductive films needs to have a relationship of 20 nm or more and 40 nm or less. When it has such a thickness relationship, it can be crystallized by heat treatment in vacuum for a short time, and it has a resistance value of 150Ω / □ or less suitable for the capacitance method, and has a high transmittance. A film can be formed.

  When the film thickness of the first transparent conductive film and the second transparent conductive film is less than 10 nm, it does not become a continuous film and does not crystallize, and when it exceeds 30 nm, the transmittance decreases and the unique yellowishness of ITO stands out. Becomes more noticeable. When the total thickness of the first transparent conductive film and the second transparent conductive film is less than 20 nm, the resistance value increases, and when it exceeds 40 nm, the transmittance decreases.

  If the transparent conductive laminate 1 according to the embodiment of the present invention is a touch panel, it can be suitably used for a capacitive touch panel in consideration of crystallinity and resistance value. Also, it can be used as a resistive film type touch panel, a flexible display electrode, or the like that requires flexibility.

  As the heat treatment of the transparent conductive layer, it is preferably conveyed by a roll-to-roll method, the conveyance speed is preferably adjusted in the range of 0.1 to 20 m / min, and the heat treatment time can be adjusted, and the transparent conductive laminate is conveyed. It is preferable that the path has a heat source that can be adjusted in the range of the surface temperature of the transparent conductive laminate from 25 ° C to 200 ° C. The type of heat source is not limited as long as the pressure can be used in the range of atmospheric pressure to 0.1 Pa, and an IR heater is an example. Accordingly, the heating temperature and the heating time can be arbitrarily selected according to the characteristics of the transparent conductive layer, and the transparent conductive layer can be crystallized.

  Next, examples and comparative examples will be described.

<Example 1>
A biaxially stretched polyethylene terephthalate (PET) film having a thickness of 125 μm was prepared as a transparent substrate, and a hard coat layer was applied on both sides. An adhesion layer, a first transparent conductive film, and a second transparent conductive film are sequentially formed on one surface of the transparent substrate 1 in-line by a magnetron sputtering method, and the film thicknesses of the first transparent conductive film and the second transparent conductive film A transparent conductive laminate was prepared with a thickness of 15 nm. For the deposition of the first transparent conductive film, the volume ratio of oxygen in the deposition atmosphere gas was set to 3.0%, and the volume ratio of oxygen in the deposition atmosphere gas of the second transparent conductive film was set to 1.0%. The first transparent conductive film was made of ITO having a Sn content of 3% by weight, the second transparent conductive film was made of ITO having a Sn content of 5% by weight, and the adhesion layer was made of silicon oxide. Next, the produced transparent conductive laminate was placed in a heat treatment apparatus, and the pressure inside the apparatus was 0.5 Pa, the heater temperature was 140 ° C., the heating time was 3 minutes, and the heat treatment was performed by roll-to-roll.

<Example 2>
For the film formation of the first transparent conductive film, except that the volume ratio of oxygen in the film formation atmosphere gas is 1.5% and the volume ratio of oxygen in the film formation atmosphere gas of the second transparent conductive film is 0.5%. A transparent conductive laminate was produced under the same configuration and film formation conditions as in Example 1. Next, the produced transparent conductive laminate was placed in a heat treatment apparatus, and the pressure inside the apparatus was 0.5 Pa, the heater temperature was 140 ° C., the heating time was 3 minutes, and the heat treatment was performed by roll-to-roll.

<Comparative Example 1>
A transparent conductive laminate was produced with the same configuration and film formation conditions as in Example 1 except that ITO having a Sn content of 3 wt% was used for the second transparent conductive film. The produced transparent conductive laminate was placed in a heat treatment apparatus, and the pressure inside the apparatus was 0.5 Pa, the heater temperature was 140 ° C., the heating time was 3 minutes, and the heat treatment was performed by roll-to-roll.

<Comparative example 2>
A transparent conductive laminate was produced with the same configuration and film forming conditions as in Example 1 except that the thickness of the first transparent conductive film was 5 nm and the thickness of the second transparent conductive film was 25 nm. The produced transparent conductive laminate was placed in a heat treatment apparatus, and the pressure inside the apparatus was 0.5 Pa, the heater temperature was 140 ° C., the heating time was 3 minutes, and the heat treatment was performed by roll-to-roll.

  The obtained transparent conductive laminate was evaluated by the following evaluation methods.

[Evaluation Method 1]
Crystallinity of transparent conductive film: Before conducting heat treatment with a heat treatment device, the transparent conductive layer portion of the transparent conductive laminate after heat treatment is analyzed using an X-ray diffractometer (manufactured by Rigaku Corporation) to confirm crystallization. did.

  Resistance value of transparent conductive film: Resistance value was measured by a 4-terminal method using a surface resistance measuring device Loresta GP manufactured by Mitsubishi Chemical Analytech.

  As shown in FIG. 5, the transparent conductive laminates obtained in Examples 1 and 2 show no indium oxide peak before heat treatment, as shown in FIG. In both of the transparent conductive laminates of Examples 1 and 2, it was confirmed that the (222) plane peak was observed and crystallization was observed. Further, as shown from the results shown in FIG. 6, the resistance value after heating is also about 130Ω / □. In Comparative Examples 1 and 2, the peak of the (222) plane itself is observed, but the resistance value remains at around 170Ω / □. This makes it possible to use a sputtering target having a different composition, and even when the volume ratio of oxygen is low, the transparent conductive film can have crystallinity with a short heat treatment, and is suitable for a capacitive touch panel. The transparent conductive laminate having the transparent conductive film can be produced.

  The present invention is used for a transparent touch panel attached as an input device on a display of an electronic device, an electrode of a flexible display, or the like.

DESCRIPTION OF SYMBOLS 1 ... Transparent conductive laminated body 2 ... Transparent base material 3a ... 1st transparent conductive film 3b ... 2nd transparent conductive film 4 ... Adhesion layer 5 ... Hard-coat layer 6 ... Heater 7 ... Heat processing apparatus

Claims (5)

  A transparent conductive laminate in which a transparent conductive film is formed on at least one surface of a transparent substrate. The transparent conductive film contains In, Sn, and O as a main component, and the Sn content is 1 wt% or more and 4 wt% or less. A first transparent conductive film made of an indium-tin composite oxide, and an indium-tin composite oxide that contains In, Sn, O as a main component, and the Sn content is more than 4 wt% and not more than 10 wt%. The film thickness of the first transparent conductive film and the second transparent conductive film is 10 nm to 30 nm, respectively, and the total thickness of both transparent conductive films is 20 nm to 40 nm. The first transparent conductive film and the second transparent film have a certain relationship and are heat-treated in a vacuum under a heating temperature of 120 ° C. or higher and 200 ° C. or lower and a heating time of 1 minute or longer and 30 minutes or shorter. Conductive film Transparent conductive laminate also characterized by crystallizing Re.   The transparent conductive laminate according to claim 1, comprising a metal or an inorganic compound between the transparent substrate and the first transparent conductive film.   The hard coat layer in contact with the transparent substrate is provided on one surface or both surfaces of the transparent substrate, and the film thickness of the hard coat layer is 1 μm or more and 8 μm or less. 2. The transparent conductive laminate according to 2. The first transparent conductive film and the second transparent conductive film are continuously formed in a vacuum using a sputtering method while transporting the transparent base material in a roll-to-roll manner, and the deposition atmosphere gas includes Ar, The method for producing a transparent conductive laminate according to any one of claims 1 to 3, wherein O ₂ is used and a volume ratio of O ₂ is 0.1 to 5%.   The said heat processing are performed by a roll toe roll system, The manufacturing method of the transparent conductive laminated body as described in any one of Claim 1 to 3 characterized by the above-mentioned.

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