JP2016207607A - Transparent conductive film composition, production method of transparent conductive sheet, and transparent conductive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition for a conductive film, which is free from viscosity increase due to long term storage and from which a transparent conductive sheet having sufficient stability of surface electric resistance value is formed.SOLUTION: In one embodiment, the composition for a transparent conductive film is provided which contains a transparent conductive particle, a binder resin and a solvent, and in which: solid component concentration of the composition for a transparent conductive film is 20 to 50 wt.%; and the solvent contains a solvent A having relative evaporation rate of 1 or more when evaporation rate of butyl acetate is 1 and a solvent B having that of less than 1 and both of the solvent A and the solvent B being one kind selected from a ketone-based solvent or an ester-based solvent. In another embodiment, the composition for a transparent conductive film is provided which is identical to the composition in the above one embodiment except that a ratio of the solvent A and the solvent B is A:B=95:5 to 70:30 by weight ratio.SELECTED DRAWING: None

Description

  Conventionally, a transparent conductive film forming a transparent conductive sheet has been produced by depositing a transparent conductive thin film such as tin-containing indium oxide on a substrate by a so-called dry process such as sputtering or vapor deposition. Since the production of the transparent conductive film using such a dry process method is performed under vacuum conditions, an expensive production apparatus is required, the production efficiency is low, and it is not suitable for mass production. Therefore, as a method for replacing the dry process method, a wet process in which a dispersion composition containing transparent conductive particles is applied to form a transparent conductive film is being studied.

  Among transparent conductive particles, tin-containing indium oxide (ITO) particles in which tin is contained in indium oxide are CRTs that are required to be prevented from static electricity and electromagnetic waves because of their high translucency for visible light and high conductivity. It has been used as a suitable material for screens, LCD screens and the like.

In addition to the tin-containing indium oxide that has been used in the transparent conductive film dry process method, the dispersion composition contains transparent conductive particles such as tin oxide, antimony-containing tin oxide, zinc oxide, and fluorine-containing tin oxide. A coating-type transparent conductive film formed by coating on a material has also been put into practical use.

JP 2012-190713 A

  Patent Document 1 describes hydrocarbons, aromatics, ketones, alcohols, glycols, glycol esters, glycol ethers and the like as solvents used for the coating type transparent conductive film. Moreover, in the manufacturing method of the coating type transparent conductive sheet provided with the coating type transparent conductive film, Patent Document 1 specifies the amount of the residual solvent in the dry coating film as a ratio to the dry film thickness, and the rate of change in surface electrical resistance value is A coating-type transparent conductive sheet having a small haze and a production method thereof are described.

However, in general, in a composition for a transparent conductive film containing transparent conductive particles, a binder resin, and a solvent, the solvent system (MEK / toluene) described in the example of Patent Document 1 has insufficient stability of the composition. In some cases, the viscosity of the transparent conductive film composition may increase due to long-term storage. Further, when a transparent conductive sheet is formed using such a composition, there is a problem that the stability of the surface electric resistance value is insufficient and the surface electric resistance value increases with time.

The composition for transparent conductive sheet film of the present invention is a composition for transparent conductive film containing transparent conductive particles, a binder resin and a solvent,
The solid content concentration of the composition for transparent conductive film is 20 to 50% by weight,
The solvent includes a solvent A having a relative evaporation rate of 1 or more and a solvent B having a relative evaporation rate of less than 1 when the evaporation rate of butyl acetate is 1, and both the solvent A and the solvent B are at least ketones. 1 type chosen from a system solvent and an ester solvent is characterized by the above-mentioned.

  Furthermore, the composition for transparent conductive film of the present invention is characterized in that the ratio of the solvent A and the solvent B is a weight ratio, and solvent A: solvent B = 95: 5 to 70:30.

  Further, in the composition for transparent conductive film of the present invention, the amount of the ketone solvent and the ester solvent in the solvent A is 90% by weight or more in total, and in the solvent B, the ketone solvent, The total amount of the ester solvent is 70% by weight or more.

Moreover, the manufacturing method of the transparent conductive sheet using the composition for transparent conductive films of this invention apply | coated the said composition for transparent conductive films on one main surface of a transparent base material, and is a transparent conductive coating film. A first step of forming
A second step of forming a transparent conductive sheet in which the transparent conductive coating film is dried to form a transparent conductive film,
In the second step, the transparent conductive film has a thickness of 0.3 to 1.5 μm,
Furthermore, when the transparent conductive coating film is dried to form a transparent conductive film, a preheating period, a constant rate drying period, a reduced rate drying period,
The sum of the time of the preheating period A and the time of the constant rate drying period B is ABti, the time of the reduced rate drying period C is Cti,
When the temperature of the preheating period A and the temperature of the constant rate drying period B is ABte, and the temperature of the decreasing rate drying period C is Cte, Expressions 1 to 4 are satisfied.
Formula 1 0.5 min <ABti
Formula 2 1 min <Cti <5 min Formula 3 20 ° C. <ABte <40 ° C.
Formula 4 70 ° C <Cte <120 ° C

Furthermore, this invention contains the transparent conductive sheet produced with said manufacturing method.

  The present invention is an invention that solves the above-mentioned problems, and has a low initial surface electrical resistance value of the transparent conductive sheet, suppresses the surface electrical resistance value from increasing with time, and is excellent in transparency. The composition for manufacturing, the manufacturing method of the transparent conductive sheet using this composition, and the transparent conductive sheet produced using this manufacturing method are provided.

  In the present application, a film formed by applying a composition for a transparent conductive film on a transparent substrate is a transparent conductive coating film, a film obtained by drying the transparent conductive coating film is a transparent conductive film, and the transparent group The material and the transparent conductive film formed on the transparent substrate are combined and defined as a transparent conductive sheet. Moreover, the composition for transparent conductive films may only be described as a composition.

[Claim 1] In the composition for transparent conductive film of the present invention, the solvent is a solvent A having a relative evaporation rate of 1 or more and a solvent B having a relative evaporation rate of less than 1 when the evaporation rate of butyl acetate is 1. The inclusion of, means that a solvent A that is relatively easy to dry and a solvent B that is difficult to dry are used in combination on the basis of the evaporation rate of butyl acetate.

  In the composition for transparent conductive film having a solid content concentration of 20 to 50% by weight, that is, the composition for transparent conductive film of the present invention containing 50 to 80% by weight of solvent, mixed solvents having different drying speeds are used as solvents. When the transparent conductive film composition is applied to a transparent substrate and dried to form a transparent conductive film, the amount of residual solvent in the transparent conductive film is reduced by the solvent A that is relatively easy to dry. . In addition, the solvent B, which is relatively difficult to dry, is gradually dried as compared with the solvent A, which is easy to dry. As a result, the filling property of the transparent conductive particles in the transparent conductive film is improved and the contact between the transparent conductive particles is increased. As a result, the surface electrical resistance value is lowered, and the temporal change of the surface electrical resistance value can be reduced. Furthermore, a transparent conductive sheet on which a transparent conductive film having a low haze is formed can be obtained.

  Both the solvent A and the solvent B include at least one selected from a ketone solvent and an ester solvent. Therefore, a ketone solvent may be used for both the solvent A and the solvent B, an ester solvent may be used, or both a ketone solvent and an ester solvent may be used.

  If the solid content concentration of the composition for transparent conductive film is less than 20% by weight, the amount of solvent in the composition for transparent conductive film increases, so even if solvent A and solvent B are used, Since the amount of the solvent to be dried is large, the filling property of the transparent conductive particles is reduced with the drying of the solvent and the contact between the transparent conductive particles is reduced, so that the surface electric resistance value cannot be lowered. When the solid content concentration is more than 50% by weight, the amount of the solvent is small, so that the dispersion of the composition for transparent conductive film becomes insufficient, and the dispersion stability is lowered. Can not. The solid concentration is preferably 25 to 45% by weight, more preferably 30 to 40% by weight.

[Claim 2] Furthermore, in the transparent conductive film, the ratio of the solvent A that is relatively easy to dry and the solvent B that is difficult to dry is in the range of solvent A: solvent B = 95: 5 to 70:30. The remaining solvent amount and the filling property of the transparent conductive particles can be balanced, and as a result, the surface electrical resistance value can be reduced and the surface electrical resistance value can be reduced over time.

  If the amount of the solvent A that is relatively easy to dry in the solvent is less than 70 parts, the amount of the solvent B that is relatively difficult to dry increases, so the amount of the residual solvent in the transparent conductive film increases, and the surface electrical resistance value The change with time increases. On the other hand, if there is more than 95 parts of solvent A that is relatively easy to dry in the solvent, there is too much solvent A that is relatively easy to dry, so the transparent conductive particles are filled in the transparent conductive film by abrupt drying. The surface electrical resistance value cannot be lowered because the contact property between the transparent conductive particles is reduced.

[Claim 3] In the solvent A, the proportion of the ketone solvent and the ester solvent is 90% by weight or more. By setting it as this range, the dispersibility of the composition can be improved, the amount of residual solvent in the transparent conductive film can be reduced, and the change over time of the surface electrical resistance value can be reduced. When the amount of the ketone solvent or the ester solvent is less than 90% by weight, the dispersibility of the composition may be lowered, and the storage stability of the composition is lowered. In the solvent A, the proportion of the ketone solvent and the ester solvent is preferably 95% by weight or more.

  In the solvent B, the ratio of the ketone solvent and the ester solvent is 70% by weight or more. By setting it as this range, while dispersibility of a composition improves, the filling property of transparent conductive particles improves, and the contact between transparent conductive particles increases, Therefore A surface electrical resistance value can be lowered | hung. When the amount of the ketone solvent or the ester solvent is less than 70% by weight, the dispersibility of the composition may be lowered, and the storage stability of the composition is lowered. In the solvent B, the proportion of the ketone solvent and the ester solvent is preferably 80% by weight or more.

  If the proportion of the ketone solvent and the ester solvent in the solvent A is 90% by weight or more, and the proportion of the ketone solvent and the ester solvent in the solvent B is 70% by weight or more, the ketone system Solvents other than solvents and ester solvents may be included.

[Claim 4] The method for producing a transparent conductive sheet of the present invention is a first method in which the transparent conductive coating film is formed by coating the transparent conductive film composition on one main surface of a transparent substrate. And a second step of forming a transparent conductive sheet in which the transparent conductive coating film is dried to form a transparent conductive film, and the thickness of the transparent conductive film after drying in the second step Is 0.3 to 1.5 μm,
Further, the second step includes a preheating period, a constant rate drying period, and a decreasing rate drying period when the transparent conductive coating film is dried to form the transparent conductive film. The total time of the rate drying period B is ABti, the time of the rate-decreasing drying period C is Cti, the temperature of the preheating period A and the temperature of the constant rate drying period B are ABte, and the temperature of the rate-decreasing drying period C is The method for producing a transparent conductive sheet according to claim 1, wherein Cte satisfies Formulas 1 to 4.
Formula 1 0.5 min <ABti
Formula 2 1 min <Cti <5 min Formula 3 20 ° C. <ABte <40 ° C.
Formula 4 70 ° C <Cte <120 ° C

  In Formula 1, the total ABti of the time of the preheating period A and the constant rate drying period B is set to be longer than 0.5 minutes, so that the solvent in the transparent conductive coating film is gradually dried to suppress the generation of voids. And the filling property of the transparent conductive particles is improved and the contact between the particles is increased. As a result, the surface electrical resistance value of the transparent conductive film can be reduced, and the temporal change of the surface electrical resistance value can be reduced. When ABti is shorter than 0.5 minutes, the drying time at low temperature is short, so the effect of suppressing the formation of voids in the transparent conductive film is reduced, and the filling property of the transparent conductive particles cannot be improved. For this reason, the surface electrical resistance value cannot be reduced, and further, the temporal change of the surface electrical resistance value cannot be reduced. The upper limit of ABti is preferably 5 minutes, and more preferably 3 minutes.

  By shortening the time Cti of the high temperature reduction rate drying period C in Formula 2 from longer than 1 minute to shorter than 5 minutes, the amount of residual solvent in the transparent conductive film is reduced and the filling property of the transparent conductive particles is improved. Further, the contact between the transparent conductive particles increases, so that the surface electrical resistance value is lowered and the change in the surface electrical resistance value with time can be reduced. When Cti is longer than 5 minutes, the transparent substrate is exposed to a high temperature environment for a long time, so that the transparent substrate is deformed and a transparent conductive sheet having a transparent conductive film cannot be obtained. Also, if Cti is shorter than 1 minute, the amount of residual solvent in the transparent conductive film increases, so that the filling property of the transparent conductive particles in the transparent conductive film cannot be improved, and the surface electrical resistance value decreases. I can't let you. Furthermore, since the residual solvent gradually evaporates from the transparent conductive film after the formation of the transparent conductive film, the change over time in the surface electrical resistance value cannot be reduced. Cti is preferably 2 to 4 minutes.

  The thickness of the transparent conductive film after drying is preferably 0.3 to 1.5 μm.

  Moreover, in Formula 3, 20 to 40 degreeC is preferable and the temperature ABte of the preheating period A and the constant rate drying period B is 25 to 35 degreeC. When the temperature is lower than 20 ° C., the temperature of the transparent conductive coating film is not sufficiently increased, and the solvent is rapidly evaporated by drying in a short time during the subsequent reduction rate drying period C. Therefore, the transparent conductive film in the transparent conductive film after drying is transparent. The filling property of the conductive particles is not improved, and a decrease in the surface electric resistance value cannot be expected. If the temperature is higher than 40 ° C., the solvent dries rapidly at the initial stage of the drying process, so that the formation of voids in the transparent conductive film cannot be suppressed, and the filling property of the transparent conductive particles cannot be improved. The surface electrical resistance value cannot be reduced. The lower limit of temperature ABte is preferably 25 ° C, and the upper limit is preferably 35 ° C.

  Furthermore, in the drying process of the transparent conductive coating film containing the solvent B having a relative evaporation rate of less than 1, the temperature Cte of the decreasing rate drying period C in Equation 4 is higher than 70 ° C. and lower than 120 ° C. The amount of residual solvent in the conductive film is reduced. As a result, the filling property of the transparent conductive particles in the transparent conductive film is improved, the contact between the transparent conductive particles is increased, the surface electrical resistance value is lowered, and the change in the surface electrical resistance value with time is reduced. be able to. When Cte exceeds 120 ° C., the evaporation effect of the solvent is saturated, and the transparent substrate may be damaged by high-temperature heating. When Cte is lower than 70, drying becomes insufficient, evaporation of the solvent B having a relative evaporation rate of less than 1 does not proceed, the amount of residual solvent in the transparent conductive film increases, and the surface electrical resistance value changes with time. . The lower limit value of the temperature Cte of the decreasing rate drying period C is preferably 80 ° C, and the upper limit value is preferably 110 ° C.

  Here, the preheating period A is a period during which the temperature rises until reaching a temperature at which the solvent in the conductive coating film starts to evaporate. The constant rate drying period B is almost balanced with the latent heat of evaporation taken from the transparent conductive coating film by the evaporation of the solvent from the transparent conductive coating film and the amount of heat received by the transparent conductive coating film from the surroundings. It is a period. Since the solvent in the transparent conductive coating film is gradually dried in this constant rate drying period B, the formation of voids is suppressed, the filling property of the transparent conductive particles is improved, and the contact between the transparent conductive particles is increased. Along with the preheating period A, it mainly affects the surface electrical resistance value.

  The decreasing rate drying period C is a period in which the coating film is solidified after the solvent in the transparent conductive coating film is almost exhausted, and the surface temperature of the coating film rises to approach the temperature of the drying atmosphere. In this decreasing rate drying period C, the solvent that did not evaporate in the constant rate drying period B, particularly the solvent B having a relative evaporation rate of less than 1, evaporates, and thus mainly affects the amount of residual solvent.

[Claim 5] The transparent conductive sheet produced by the production method of the present application has a low surface electrical resistance value and a change in the surface electrical resistance value over time, and further has a high total light transmittance and a low haze. Sheets can be provided.

<Composition for transparent conductive sheet>
The coating composition can be obtained by preparing transparent conductive particles and a binder resin by dispersing them in a solvent.

<< Transparent conductive particles >>
The transparent conductive particles are not particularly limited as long as the particles have both transparency and conductivity. For example, conductive metal oxide particles, conductive nitride particles, and the like can be used. Examples of the conductive metal oxide particles include metal oxide particles such as indium oxide, tin oxide, zinc oxide, and cadmium oxide. In addition, conductive metal oxide particles doped with tin, antimony, aluminum, gallium, with one or more metal oxides selected from the group consisting of indium oxide, tin oxide, zinc oxide and cadmium oxide as main components, Examples include tin-containing indium oxide (ITO) particles, antimony-containing tin oxide (ATO) particles, aluminum-containing zinc oxide (AZO) particles, gallium-containing zinc oxide (GZO) particles, and conductive metal oxide particles obtained by replacing ITO with aluminum. Can also be used. Among these, ITO particles are particularly preferable from the viewpoint of excellent transparency and conductivity.

  From the viewpoint of conductivity, the amount of tin added to the ITO particles is preferably 1 to 20% by weight in terms of tin oxide. The conductivity is improved by adding tin to ITO. However, when the amount of tin added is less than 1% by weight, the improvement in conductivity tends to be poor. There is a small tendency.

  The transparent conductive particles preferably have an average primary particle diameter in the range of 10 to 200 nm. If it is smaller than 10 nm, the dispersion treatment becomes difficult and the particles tend to aggregate, or the cloudiness increases and the optical properties tend to be inferior. On the other hand, if it is larger than 200 nm, the cloudiness tends to increase due to the scattering of visible light by the particles. Here, the average primary particle diameter is, for example, at least 100 particles after observing and measuring the particle diameter of each particle using an electron microscope on the surface or cross section of the transparent conductive film formed on the transparent substrate. The average particle diameter obtained by averaging the particle diameters of the particles.

<< Binder resin >>
It is preferable that content of the said binder resin contained in the said composition for transparent conductive films is 5-18 weight part with respect to 100 weight part of transparent conductive particles. If the amount is less than 5 parts by weight, the effect of improving the strength of the coating film tends to be poor. If the amount is more than 18 parts by weight, the surface electrical resistance tends to increase, and good conductivity may not be obtained.

  Although it does not specifically limit as said binder resin, Resin whose glass transition temperature is 30-120 degreeC is preferable. By using a resin having a glass transition temperature of 30 to 120 ° C. as the binder resin, the transparent conductive film can have appropriate flexibility. As the binder resin, for example, a thermoplastic resin having a glass transition temperature of 30 to 120 ° C. or a radiation curable resin having a glass transition temperature of 30 to 120 ° C. can be used. The said binder resin may be used independently or may be used in combination of 2 or more type. Here, the measurement of the glass transition temperature can be performed in accordance with Japanese Industrial Standard (JIS) K7121 using a DSC method based on so-called thermal analysis.

  As the thermoplastic resin having a glass transition temperature of 30 to 120 ° C., for example, an acrylic resin or a polyester resin can be used.

  Examples of the acrylic resin include Dianal BR-60, Dialnal BR-64, Dialnal BR-75, Dialnal BR-77, Dialnal BR-80, and Dialnal BR-83 manufactured by Mitsubishi Rayon Co., Ltd. Dialnal BR-87, dialnal BR-90, dialnal BR-95, dialnal BR-96, dialnal BR-100, dialnal BR-101, dialnal BR-105, dialnal BR-106, dialnal BR-107, Dialnal BR-108, Dialnal BR-110, Dialnal BR-113, Dialnal BR-122, Dialnal BR-605, Dialnal MB-2539, Dialnal MB-2389, Dialnal MB- 2487, Dialnal MB-2660, Iyanaru MB-2952, Dianal MB-3015, and the like DIANAL MB-7033.

  Examples of the polyester resin include Byron 200, Byron 220, Byron 226, Byron 240, Byron 245, Byron 270, Byron 280, Byron 290, Byron 296, Byron 660, Byron 885, Byron GK110, Byron manufactured by Toyobo Co., Ltd. GK250, Byron GK360, Byron GK640, Byron GK880 and the like can be mentioned.

Although it does not specifically limit as said radiation curable resin whose said glass transition temperature is 30-120 degreeC, For example, an acrylate monomer, a methacrylate monomer, an epoxy acrylate, a urethane acrylate, a polyester acrylate, an acrylic oligomer etc. are mentioned. Specifically, isobornyl acrylate, 2-phenoxyethyl methacrylate, tripropylene glycol diacrylate, diethylene glycol diacrylate, ethoxylated bisphenol A dimethacrylate, trimethylolpropane triacrylate, dipentaerythritol pentaacrylate, etc. may be used. it can. Here, the glass transition temperature of the radiation curable resin is, for example, an ultraviolet polymerization initiator such as 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1- based on 100 parts by weight of the resin. It is preferable to use a measured value after radiation curing treatment obtained by adding 5 parts by weight of ON and irradiating with ultraviolet rays at 500 mJ / cm 2.

  Moreover, you may use thermosetting resins, such as an epoxy resin, as said resin whose glass transition temperature is 30-120 degreeC.

  When a radiation curable resin is used as the binder resin, the curing treatment may be performed by radiation such as ultraviolet rays, electron beams, and β rays. Among these, it is convenient to use ultraviolet rays. In this case, an ultraviolet polymerization initiator may be further added to the radiation curable resin. As the ultraviolet polymerization initiator, the following can be used. For example, benzoin isopropyl ether, benzophenone, 2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexyl phenyl ketone, 2,4-diethylthioxanthone, methyl o-henzoylbenzoate, 4,4-bisdiethylaminobenzophenone, 2, 2-diethoxyacetophene, benzyl, 2-chlorothioxanthone, diisopropylthioxanthone, 9,10-anthraquinone, benzoin, benzoin methyl ether, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl -Propiophenone, 4-isopropyl-2-hydroxy-2-methylpropiophenone, α, α-dimethoxy-α-phenylacetone and the like can be used. The said ultraviolet polymerization initiator may be used independently and may be used in combination of 2 or more type.

  The ultraviolet polymerization initiator is preferably added in an amount of 1 to 20 parts by weight with respect to 100 parts by weight of the radiation curable resin. When the amount is less than 1 part by weight, the curability of the resin is inferior, or the strength of the transparent conductive film tends to be inferior. Moreover, when it exceeds 20 weight part, since bridge | crosslinking does not advance fully, it exists in the tendency for the intensity | strength of a transparent conductive film to be inferior.

<< solvent >>
As the solvent, a solvent A having a relative evaporation rate of 1 or more when a vaporization rate of butyl acetate is 1, and a solvent B having a relative evaporation rate of less than 1 are used. The relative evaporation rate is a relative evaporation rate when the evaporation rate of butyl acetate is 1, and the higher the value, the easier the evaporation, and the smaller the value, the less evaporation.

Both the solvent A and the solvent B include at least one selected from a ketone solvent and an ester solvent. Therefore, a ketone solvent may be used for both the solvent A and the solvent B, an ester solvent may be used, or both a ketone solvent and an ester solvent may be used.
As the ketone solvent of the solvent A having a relative evaporation rate of 1 or more, acetone, methyl ethyl ketone (MEK), or methyl isobutyl ketone (MIBK) can be used.

  As the ester solvent of the solvent A having a relative evaporation rate of 1 or more, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, isobutyl acetate, butyl acetate can be used.

  Cyclopentanone, cyclohexanone, and cycloheptanone can be used as the ketone solvent of the solvent B having a relative evaporation rate of less than 1.

  As the ester solvent of the solvent B having a relative evaporation rate of less than 1, amyl acetate, methyl amyl acetate, methyl lactate, and ethyl lactate can be used.

  Both the ester solvent of the solvent A having a relative evaporation rate of 1 or more and the ester solvent of the solvent B having a relative evaporation rate of less than 1 are preferably ester solvents having no glycol structure. A ketone-based solvent and an ester-based solvent, particularly an ester-based solvent having no glycol structure are preferable because the dispersibility (wetting property) of the metal oxide is good and the composition is stable.

<< Other additives >>
The composition for transparent conductive sheet may contain a dispersant, a plasticizer, an antistatic agent and the like in addition to the transparent conductive particles and the binder resin.

  As the dispersant, it is preferable to use a dispersant containing at least an anionic functional group, and it is more preferable to use a polyester resin containing an anionic functional group or an acrylic resin containing an anionic functional group. For example, carboxylic acid-containing acrylic resins, acid-containing polyester resins, acid and base-containing polyester resins, and the like can be used. Specifically, dialnal MR-2539, dialnal MB-2389, dialnal MB-2660, dialnal MB-3015, dialnal BR-60, dialnal BR-64, dialnal BR- manufactured by Mitsubishi Rayon Co., Ltd. 77, Dialnal BR-84, Dialnal BR-83, Dialnal BR-87, Dialnal BR-106, Dialnal BR-113, etc., or Solspirs 3000, Solspurs 21000, Solspurs 26000, Solspurs 32000, manufactured by Abyssia Commercially available products such as Solspurs 36000, Solspers 41000, Solspers 43000, Solspers 44000, Solspers 45000, Solspers 56000, and the like can be used.

<Transparent substrate>
The transparent substrate is not particularly limited as long as it is formed of a transparent material. For example, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyolefins, cellulose resins such as cellulose triacetate, amide resins such as nylon and aramid, polyether resins such as polyphenylene ether and polysulfone ether, polycarbonate resins, A film or sheet made of a material such as polyamide resin, polyimide resin, polyamideimide resin, or aromatic polyamide resin can be used. Further, glass, ceramics or the like may be used. The thickness of the transparent substrate is usually preferably from 3 to 300 μm, more preferably from 25 to 200 μm.

  In the present invention, the term “transparent” means that the total light transmittance measured in accordance with JIS K7161: 1997 is 75% or more.

  Additives such as antioxidants, flame retardants, heat resistance inhibitors, ultraviolet absorbers, lubricants and antistatic agents may be added to the transparent substrate. Furthermore, in order to improve the adhesion to the transparent conductive film formed on the transparent substrate, an easy-adhesive layer (for example, a primer layer) is provided on the surface of the substrate, or a surface such as corona treatment or plasma treatment. Processing.

<Transparent conductive sheet>
The transparent conductive sheet of the present application has a total light transmittance of preferably 75% or more, and more preferably 85% or more. The haze is preferably 2% or less, more preferably 1% or less. By setting to such a range, for example, it can be suitably used for electrodes for touch panels and light control films, transparent surface heating elements, antistatic films for displays, and transparent conductive sheets for electromagnetic wave shielding materials.

<Method for preparing composition for transparent conductive film>
The preparation method of the composition for transparent conductive films should just disperse | distribute transparent conductive particles and binder resin in a solvent, and the dispersion method is not specifically limited, respectively. For example, a dispersion process using a bead mill such as a sand grind mill, an ultrasonic disperser, a three roll mill, or the like can be mentioned, but a dispersion process using a bead mill is preferable from the viewpoint of better dispersibility.

<Formation of transparent conductive film>
The method for forming the transparent conductive coating film by coating the transparent conductive film composition on the transparent substrate is not particularly limited as long as it is a coating method capable of forming a smooth coating film. For example, a coating method such as a gravure roll method, a micro gravure roll method, a spray method, a spin method, a knife method, a kiss method, a squeeze method, a reverse roll method, a dip method, and a bar coat method can be used.

  As a method for drying the coating film, hot air may be applied from the transparent conductive coating film side or from the transparent substrate side. Moreover, you may make a heat source contact the transparent base material side directly. Moreover, you may dry a transparent conductive coating film by a non-contact method with a heat source using an infrared heater, a far-infrared heater, etc. It may be naturally dried in a temperature and humidity controlled space

<Example>
Hereinafter, the present invention will be described in detail based on examples. However, the present invention is not limited to the following examples. Further, unless otherwise indicated, in the following, “part” means “part by weight”.

まず、以下の組成の混合物を、分散メディアとして直径０．１ｍｍのジルコニアビーズを用い、ペイントコンディショナーを用いて分散処理した。 <Preparation of composition A for transparent conductive film>

First, a mixture having the following composition was dispersed using a paint conditioner using zirconia beads having a diameter of 0.1 mm as a dispersion medium.

A mixture of the following components was added to 100 parts of the dispersion obtained above, stirred for 30 minutes, and then passed through a filter (glass fiber filter “AP-25 manufactured by Nihon Millipore)” A "was obtained.

<Preparation of composition B for transparent conductive film>
First, a mixture having the following composition was dispersed using a paint conditioner using zirconia beads having a diameter of 0.1 mm as a dispersion medium.

A mixture of the following components was added to 100 parts of the dispersion obtained above, stirred for 30 minutes, and then passed through a filter (glass fiber filter “AP-25 manufactured by Nihon Millipore)” B "was obtained.

<Preparation of transparent conductive film composition C>
First, a mixture having the following composition was dispersed using a paint conditioner using zirconia beads having a diameter of 0.1 mm as a dispersion medium.

A mixture of the following components was added to 100 parts of the dispersion obtained above, stirred for 30 minutes, and then passed through a filter (glass fiber filter “AP-25 manufactured by Nihon Millipore)” C "was obtained.

<Preparation of composition D for transparent conductive film>
First, a mixture having the following composition was dispersed using a paint conditioner using zirconia beads having a diameter of 0.1 mm as a dispersion medium.

A mixture of the following components was added to 100 parts of the dispersion obtained above, stirred for 30 minutes, and then passed through a filter (glass fiber filter “AP-25 manufactured by Nihon Millipore)” D "was obtained.

<Preparation of composition E for transparent conductive film>
First, a mixture having the following composition was dispersed using a paint conditioner using zirconia beads having a diameter of 0.1 mm as a dispersion medium.

A mixture of the following components was added to 100 parts of the dispersion obtained above, stirred for 30 minutes, and then passed through a filter (glass fiber filter “AP-25 manufactured by Nihon Millipore)” E "was obtained.

<Preparation of transparent conductive film composition F>
First, a mixture having the following composition was dispersed using a paint conditioner using zirconia beads having a diameter of 0.1 mm as a dispersion medium.

A mixture of the following components was added to 100 parts of the dispersion obtained above, stirred for 30 minutes, and then passed through a filter (glass fiber filter “AP-25 manufactured by Nihon Millipore)” F "was obtained.

<Preparation of transparent conductive film composition G>
First, a mixture having the following composition was dispersed using a paint conditioner using zirconia beads having a diameter of 0.1 mm as a dispersion medium.

A mixture of the following components was added to 100 parts of the dispersion obtained above, stirred for 30 minutes, and then passed through a filter (glass fiber filter “AP-25 manufactured by Nihon Millipore)” G "was obtained.

<Preparation of transparent conductive film composition H>
First, a mixture having the following composition was dispersed using a paint conditioner using zirconia beads having a diameter of 0.1 mm as a dispersion medium.

A mixture of the following components was added to 100 parts of the dispersion obtained above, stirred for 30 minutes, and then passed through a filter (glass fiber filter “AP-25 manufactured by Nihon Millipore)” H "was obtained.

<Preparation of transparent conductive film composition I>
First, a mixture having the following composition was dispersed using a paint conditioner using zirconia beads having a diameter of 0.1 mm as a dispersion medium.

A mixture of the following components was added to 100 parts of the dispersion obtained above, stirred for 30 minutes, and then passed through a filter (glass fiber filter “AP-25 manufactured by Nihon Millipore)” I "was obtained.

<Preparation of transparent conductive film composition J>
First, a mixture having the following composition was dispersed using a paint conditioner using zirconia beads having a diameter of 0.1 mm as a dispersion medium.

A mixture of the following components was added to 100 parts of the dispersion obtained above, stirred for 30 minutes, and then passed through a filter (glass fiber filter “AP-25 manufactured by Nihon Millipore)” J ".

<Preparation of transparent conductive film composition K>
First, a mixture having the following composition was dispersed using a paint conditioner using zirconia beads having a diameter of 0.1 mm as a dispersion medium.

A mixture of the following components was added to 100 parts of the dispersion obtained above, stirred for 30 minutes, and then passed through a filter (glass fiber filter “AP-25 manufactured by Nihon Millipore)” K "was obtained.

  The compositions of the transparent conductive film composition A to the transparent conductive film composition K are summarized in Tables 1 to 3.

<Preparation of transparent conductive sheet>
Examples 1 to 13
Using a bar coater, apply “Transparent conductive film composition A” to a transparent substrate (polyester film “KEL86W manufactured by Teijin DuPont, thickness: 125 μm) so that the film thickness after drying is 0.7 μm. A transparent conductive coating film was then formed, and then dried to form a transparent conductive sheet having a transparent conductive film formed thereon, and the temperature at this time was defined as the temperature of the preheating period A and the temperature ABte of the constant rate drying period B, The time when drying was performed using an explosion-proof dryer was defined as the temperature Cte of the reduced rate drying period C, and the time was defined as Cti. ABte, ABti, Cte, and Cti are shown in Table 4 The transparent conductive sheets of Examples 1 to 13 were obtained.

Example 14
Using a bar coater, “Transparent conductive film composition B” is applied to a transparent base material (polyester film “KEL86W, thickness: 125 μm, manufactured by Teijin DuPont) using a bar coater to form a transparent conductive coating film. Then, a transparent conductive sheet was formed by drying to form a transparent conductive film having a film thickness of 0.7 μm, with the temperature at this time as the temperature of the preheating period A and the temperature ABte of the constant rate drying period B. Then, the temperature when drying using an explosion-proof dryer was defined as the temperature Cte of the decreasing rate drying period C, and the time was defined as Cti. ABte, ABti, Cte, and Cti are described in Table 5, respectively. The transparent conductive sheet of Example 14 was obtained.

Example 15
Using a bar coater, “Transparent conductive film composition C” is applied to a transparent substrate (polyester film “KEL86W manufactured by Teijin DuPont, thickness: 125 μm) using a bar coater to form a transparent conductive coating film. Then, a transparent conductive sheet was formed by drying to form a transparent conductive film having a film thickness of 0.7 μm, with the temperature at this time as the temperature of the preheating period A and the temperature ABte of the constant rate drying period B. Then, the temperature when drying using an explosion-proof dryer was defined as the temperature Cte of the decreasing rate drying period C, and the time was defined as Cti. ABte, ABti, Cte, and Cti are described in Table 5, respectively. The transparent conductive sheet of Example 15 was obtained.

Example 16
Using a bar coater, “Transparent conductive film composition D” is applied to a transparent substrate (polyester film “KEL86W, thickness: 125 μm, manufactured by Teijin DuPont” using a bar coater to form a transparent conductive coating film. Then, a transparent conductive sheet was formed by drying to form a transparent conductive film having a film thickness of 0.7 μm, with the temperature at this time as the temperature of the preheating period A and the temperature ABte of the constant rate drying period B. Then, the temperature when drying using an explosion-proof dryer was defined as the temperature Cte of the decreasing rate drying period C, and the time was defined as Cti. ABte, ABti, Cte, and Cti are described in Table 5, respectively. The transparent conductive sheet of Example 16 was obtained.

Example 17
Using a bar coater, “Transparent conductive film composition E” is applied to a transparent substrate (polyester film “KEL86W, thickness: 125 μm, manufactured by Teijin DuPont) using a bar coater to form a transparent conductive coating film. Then, a transparent conductive sheet was formed by drying to form a transparent conductive film having a film thickness of 0.7 μm, with the temperature at this time as the temperature of the preheating period A and the temperature ABte of the constant rate drying period B. Subsequently, the temperature when drying using an explosion-proof dryer was defined as the temperature Cte of the decreasing rate drying period C, and the time was defined as Cti. ABte, ABti, Cte, and Cti are listed in Table 6, respectively. The transparent conductive sheet of Example 17 was obtained.

Example 18
Using a bar coater, “Transparent conductive film composition F” is applied to a transparent substrate (polyester film “KEL86W, thickness: 125 μm, manufactured by Teijin DuPont) using a bar coater to form a transparent conductive coating film. Then, a transparent conductive sheet was formed by drying to form a transparent conductive film having a film thickness of 0.7 μm, with the temperature at this time as the temperature of the preheating period A and the temperature ABte of the constant rate drying period B. Subsequently, the temperature when drying using an explosion-proof dryer was defined as the temperature Cte of the decreasing rate drying period C, and the time was defined as Cti. ABte, ABti, Cte, and Cti are listed in Table 6, respectively. The transparent conductive sheet of Example 18 was obtained.

Example 19
Using a bar coater, “Transparent conductive film composition G” is applied to a transparent substrate (polyester film “KEL86W manufactured by Teijin DuPont, thickness: 125 μm) using a bar coater to form a transparent conductive coating film. Then, a transparent conductive sheet was formed by drying to form a transparent conductive film having a film thickness of 0.7 μm, with the temperature at this time as the temperature of the preheating period A and the temperature ABte of the constant rate drying period B. Subsequently, the temperature when drying using an explosion-proof dryer was defined as the temperature Cte of the decreasing rate drying period C, and the time was defined as Cti. ABte, ABti, Cte, and Cti are listed in Table 6, respectively. The transparent conductive sheet of Example 19 was obtained.

Example 20
Using a bar coater, “Transparent conductive film composition H” is applied to a transparent substrate (polyester film “KEL86W, thickness: 125 μm, manufactured by Teijin DuPont) using a bar coater to form a transparent conductive coating film. Then, a transparent conductive sheet was formed by drying to form a transparent conductive film having a film thickness of 0.7 μm, with the temperature at this time as the temperature of the preheating period A and the temperature ABte of the constant rate drying period B. Subsequently, the temperature when drying using an explosion-proof dryer was defined as the temperature Cte of the decreasing rate drying period C, and the time was defined as Cti. ABte, ABti, Cte, and Cti are listed in Table 6, respectively. The transparent conductive sheet of Example 20 was obtained.

Example 21
Using a bar coater, “Transparent conductive film composition I” is applied to a transparent base material (polyester film “KEL86W, thickness: 125 μm, manufactured by Teijin DuPont” using a bar coater to form a transparent conductive coating film. Then, a transparent conductive sheet was formed by drying to form a transparent conductive film having a film thickness of 0.7 μm, with the temperature at this time as the temperature of the preheating period A and the temperature ABte of the constant rate drying period B. Subsequently, the temperature when drying using an explosion-proof dryer was defined as the temperature Cte of the decreasing rate drying period C, and the time was defined as Cti. ABte, ABti, Cte, and Cti are listed in Table 6, respectively. The transparent conductive sheet of Example 21 was obtained.

Comparative Example 1
Using a bar coater, the solvent A does not contain a ketone solvent or an ester solvent. “The transparent conductive film composition J is applied to a transparent substrate (polyester film“ KEL86W, thickness: 125 μm, manufactured by Teijin DuPont ”). A transparent conductive coating film was formed by coating, and then dried to form a transparent conductive sheet having a thickness of 0.7 μm. The temperature at this time was defined as the temperature during the preheating period A and the temperature ABte during the constant rate drying period B, and the time as ABti. Subsequently, the temperature when drying using an explosion-proof dryer was set as the temperature Cte of the decreasing rate drying period C, and the time was set as Cti. ABte, ABti, Cte, and Cti were set to the conditions shown in Table 6 to obtain a transparent conductive sheet of Comparative Example 1.

Comparative Example 2
Using a bar coater, the solvent B does not contain a ketone solvent or an ester solvent. “The transparent conductive film composition K is applied to a transparent substrate (polyester film“ KEL86W, thickness: 125 μm, manufactured by Teijin DuPont ”) A transparent conductive coating film was formed by coating, and then dried to form a transparent conductive sheet having a thickness of 0.7 μm. The temperature at this time was defined as the temperature during the preheating period A and the temperature ABte during the constant rate drying period B, and the time as ABti. Then, the temperature when drying using an explosion-proof dryer was set to the temperature Cte of the decreasing rate drying period C, and time was set to Cti, and the transparent conductive sheet was obtained. ABte, ABti, Cte, and Cti were changed to the conditions shown in Table 6, and the composition of Comparative Example 6 was applied and dried to obtain a transparent conductive sheet.

<Initial surface electrical resistance value>
From a transparent conductive sheet having a transparent conductive film having a thickness of 0.7 μm obtained by applying and drying the composition for transparent conductive film within 24 hours after the dispersion treatment, a length of 75 mm and a width of 75 mm The sample was cut out, and the initial surface electrical resistance value on the transparent conductive film side was measured using a resistivity meter (“Loresta MCP-T610 manufactured by Mitsubishi Chemical Analytech Co., Ltd.) at the center of the coated surface. Those with less than 10,000 Ω / □ were evaluated as “◯”, those with 10,000-15000 Ω / □ as “Δ”, and those with 15000 Ω / □ or more as “×”.

<Haze>
The optical properties were evaluated by measuring haze. The lower the haze value, the better the optical properties. The measurement material used the transparent conductive sheet which formed the transparent conductive film with a film thickness of 0.7 micrometer obtained by apply | coating and drying within 24 hours after the dispersion process for the composition for transparent conductive films. The haze was measured by using a haze meter ("NDH2000 Nippon Denshoku Co., Ltd.") in accordance with JIS K 7361 (mode: Hohou 1) to evaluate the haze including the transparent substrate. The haze was less than 1.0%. The thing was made into (circle), the thing of 1.0-2.0% was set to (triangle | delta), and the thing 2.0% or more was made into x.

<Storage stability of composition>
The composition for transparent conductive film was dispersed and then stored for 7 days in a 25 ° C. environment. A sample having a length of 75 mm and a width of 75 mm was cut out from a transparent conductive sheet on which a transparent conductive film having a thickness of 0.7 μm was formed by applying and drying this composition. The surface electrical resistance value on the transparent conductive film side was measured using a meter (“Loresta MCP-T610 manufactured by Mitsubishi Chemical Analytech Co., Ltd.). From this value and the initial surface electrical resistance value measured above, the following equation was obtained. When the calculated value is less than 5%, the storage stability of the composition for transparent conductive film is ◯, 5% or more and less than 10% is stored and the storage stability is △ 10% or more. Stability was set as x.
(Surface electrical resistance value after storage of composition for transparent conductive film−initial surface electrical resistance value) / initial surface electrical resistance value × 100

<Surface electrical resistance value change with time of transparent conductive sheet>
After the dispersion treatment, the transparent conductive film composition was applied and dried within 24 hours to obtain a transparent conductive sheet on which a transparent conductive film having a dry film thickness of 0.7 μm was formed. This transparent conductive sheet was allowed to stand in a dark room at 23 ° C. and 50% relative humidity for 24 hours, and then a sample having a length of 75 mm and a width of 75 mm was cut out and a resistivity meter (“Loresta MCP-T610 Mitsubishi Chemical) was applied to the center of the coated surface. The surface electrical resistance value after storage of the transparent conductive sheet on the side of the transparent conductive film was measured using the following formula from this value and the initial surface electrical resistance value measured above. When the calculated value of the surface resistance of the transparent conductive film sheet over time is less than 5%, the storage stability of the sheet is good. When the value is 5% or more and less than 10%, the storage stability of the sheet is Δ10. The sheet having a storage stability of% or more was evaluated as x.
(Surface electrical resistance value after storage of transparent conductive sheet−initial surface electrical resistance value) / initial surface electrical resistance value × 100

  The compositions of the transparent conductive film compositions A to K produced in each example are summarized in Tables 1 to 3. Moreover, the measurement result of the transparent conductive sheet produced by each Example and the comparative example was put together in Tables 4-6.

  From Example 1 to Example 13, when the transparent conductive film formed by applying the composition for transparent conductive film of the present invention to a transparent substrate was dried to form a transparent conductive film, the film was relatively dried. The amount of residual solvent in the transparent conductive film can be reduced by the easy solvent A. In addition, the solvent B, which is relatively difficult to dry, is gradually dried as compared with the solvent A, which is easy to dry. As a result, the storage stability of the transparent conductive film composition is improved, the initial surface electric resistance value is decreased, and the surface The electrical resistance value change with time could be reduced. Furthermore, a transparent conductive sheet having a low haze value could be obtained.

In Comparative Example 1, toluene is used as solvent A, which is relatively easy to dry, and at least one selected from ketone solvents and ester solvents is not used. As the storage stability of the resin deteriorated, the initial surface electrical resistance value and haze value increased.
In Comparative Example 2, propylene glycol monomethyl ether is used for solvent B, which is relatively difficult to dry, and at least one selected from ketone solvents and ester solvents is not used. The storage stability of the composition for use decreased.

Claims (5)

A composition for transparent conductive film comprising transparent conductive particles, a binder resin and a solvent,
The solid content concentration of the composition for transparent conductive film is 20 to 50% by weight,
The solvent includes a solvent A having a relative evaporation rate of 1 or more when the evaporation rate of butyl acetate is 1, and a solvent B having a relative evaporation rate of less than 1.
Both the solvent A and the solvent B contain at least one selected from a ketone solvent and an ester solvent, the composition for transparent conductive films. It is a composition for transparent conductive films of Claim 1, Comprising:
A composition for a transparent conductive film, wherein a ratio of the solvent A and the solvent B is a weight ratio of solvent A: solvent B = 95: 5 to 70:30. It is a composition for transparent conductive films of Claim 1 or 2, Comprising:
In the solvent A, the amount of the ketone solvent and the ester solvent is 90% by weight or more in total,
In the solvent B, the amount of the ketone solvent and the ester solvent is 70% by weight or more in total. A method for producing a transparent conductive sheet using the composition for transparent conductive film according to claim 1,
A first step of coating the transparent conductive film composition on one main surface of the transparent substrate to form a transparent conductive coating film;
A second step of forming a transparent conductive sheet in which the transparent conductive coating film is dried to form a transparent conductive film,
In the second step, the transparent conductive film has a thickness of 0.3 to 1.5 μm,
Furthermore, when the transparent conductive coating film is dried to form a transparent conductive film, a preheating period, a constant rate drying period, a reduced rate drying period,
The sum of the time of the preheating period A and the time of the constant rate drying period B is ABti, the time of the reduced rate drying period C is Cti,
The equation (1) to (4) are satisfied, where the temperature of the preheating period A and the temperature of the constant rate drying period B is ABte, and the temperature of the decreasing rate drying period C is Cte. Method for producing a transparent conductive sheet.
Formula 1 0.5 min <ABti
Formula 2 1 min <Cti <5 min Formula 3 20 ° C. <ABte <40 ° C.
Formula 4 70 ° C <Cte <120 ° C   The transparent conductive sheet manufactured with the manufacturing method of Claim 4.