JP5962995B2 - Base film for transparent conductive film for touch panel and transparent conductive film for touch panel - Google Patents

Description

  The present invention relates to a base film of a transparent conductive film for a touch panel and a transparent conductive film for a touch panel using the base film. Specifically, the present invention relates to a base film for obtaining a transparent conductive film for a touch panel having good visibility and a small surface resistance value.

  In the following description, “transparent conductive film for touch panel” is sometimes simply referred to as “transparent conductive film”, and the expression “transparent conductive film” is referred to as “transparent conductive film for touch panel” unless otherwise specified. means.

  As a base film of a transparent conductive film, a hard coat film in which a hard coat layer is provided on a base film is generally known. A transparent conductive film is obtained by providing a transparent conductive film on one side or both sides of such a base film.

  Moreover, in order to improve the visibility of the transparent conductive film of a transparent conductive film, the base film which provided the various functional layers on the base film is proposed.

  For example, in order to adjust the color tone (color tone) of a transparent conductive film, a base film in which an optical functional layer is laminated on a base film has been proposed (Patent Documents 1 to 3), and a patterned transparent conductive film has been proposed. It is known as a base film in which a refractive index adjusting layer is laminated on a base film in order to suppress a phenomenon in which a film pattern is visually recognized (so-called “bone appearance”) (Patent Documents 4 to 8).

JP 2000-301648 A JP 2003-251751 A JP 2004-47456 A JP 2009-76432 A JP 2010-208169 A JP 2011-37258 A JP 2011-134464 A JP 2011-248612 A

  As described in the above-mentioned patent documents, the optical functional layer and the refractive index adjustment layer can be formed by a method of laminating a high refractive index material or a low refractive index material by a sputtering method, or a metal oxide having a high refractive index. It is generally known that a coating liquid containing fine particles, low refractive index silica particles and a resin is laminated by a wet coating method.

  The wet coating method is more productive than the sputtering method. However, it is obtained by laminating a transparent conductive film on an optical functional layer or a refractive index adjusting layer formed by laminating a coating liquid containing particles such as metal oxide fine particles or silica particles and a resin by a wet coating method. The transparent conductive film has a problem that the original surface resistance value of the transparent conductive film cannot be obtained. This is presumably due to the smoothness of the surface on which the transparent conductive film is laminated (the surface of the optical function layer or the surface of the refractive index adjustment layer).

  On the other hand, bringing the color tone of the transparent conductive film closer to neutral colorlessness and suppressing the “bone appearance” in which the patterned transparent conductive film pattern is visually recognized are important for improving the visibility of the transparent conductive film. It is a problem. The above-described visibility problems (color tone, bone appearance, transmittance) of the transparent conductive film tend to improve as the thickness of the transparent conductive film decreases.

  That is, the transparent conductive film of the transparent conductive film is preferably a thin film within a range where a set surface resistance value can be obtained from the viewpoint of the visibility of the transparent conductive film.

  Accordingly, an object of the present invention is to provide a base film in which a transparent conductive film with good visibility of a transparent conductive film and a low resistance can be obtained in view of the above-mentioned problems of the prior art. Another object of the present invention is to provide a transparent conductive film for a touch panel using the base film of the present invention.

The above object of the present invention has been basically achieved by the following invention.
1) Transparent conductive film for touch panel having a high refractive index layer having a refractive index of 1.60 to 1.80 and a low refractive index layer having a refractive index of 1.52 or less in this order on at least one surface of the base film. The high refractive index layer and the low refractive index layer each contain a resin as a main component, and the average roughness (Ra) of the surface of the low refractive index layer is less than 1 nm. A base film of a transparent conductive film for touch panels.
2) The transparent conductive film for touch panels which has a transparent conductive film on the low-refractive-index layer of the base film of the transparent conductive film for touch panels as described in said 1).

  ADVANTAGE OF THE INVENTION According to this invention, even if the thickness of a transparent conductive film is a comparatively thin film, it is possible to implement | achieve low resistance, and the transparent conductive film for touchscreens which can improve the visibility of a transparent conductive film The base film can be provided. Moreover, by using the base film of the present invention, a transparent conductive film for a touch panel having low resistance and good visibility can be obtained.

  The base film of the present invention has a high refractive index layer and a low refractive index layer in this order on at least one surface of the base film. The refractive index of the high refractive index layer is 1.60 to 1.80, and the refractive index of the low refractive index layer is 1.52 or less. Each of the high refractive index layer and the low refractive index layer contains a resin as a main component. And the average roughness (Ra) of the surface of a low refractive index layer is less than 1 nm.

  In the present invention, the laminated structure of the high refractive index layer and the low refractive index layer is an optical functional layer for adjusting the color tone of the transparent conductive film or a refractive index adjustment for suppressing the appearance of the patterned transparent conductive film. Functions as a layer. In particular, in the present invention, the laminated structure of the high refractive index layer and the low refractive index layer is suitable for suppressing the bone appearance of the patterned transparent conductive film.

  In the present invention, each of the high refractive index layer and the low refractive index layer contains a resin as a main component, whereby the average roughness (Ra) of the surface of the low refractive index layer can be less than 1 nm. That is, in the present invention, the surface of the low refractive index layer is extremely smooth. The average roughness (Ra) of the low refractive index layer surface is preferably 0.8 nm or less, more preferably 0.6 nm or less, and particularly preferably 0.5 nm or less. The lower limit average roughness (Ra) is about 0.1 nm.

  The average roughness (Ra) of the surface of the low refractive index layer represents the arithmetic average of the deviation from the center plane, and is determined by the following formula.

_Where Z _cp is the Z value in the center plane, Z _i is the Z value at each data point, and N is the number of data points in the region.

  The above average roughness (Ra) can be measured using an atomic force microscope.

  The transparent conductive film laminated on such a very smooth low refractive index layer has a small surface resistance value even if it is a relatively thin film. Furthermore, the visibility (color tone and bone appearance) of the transparent conductive film is improved by combining the relatively thin transparent conductive film and the laminated structure of the high refractive index layer and the low refractive index layer of the present invention.

[Base film]
The material of the base film in the present invention is not particularly limited, and examples thereof include polyester (for example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate), polymethyl methacrylate, acrylic resin, polycarbonate, polystyrene. , Triacetyl cellulose, polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, polyethylene, ethylene-vinyl acetate copolymer, polyvinyl butyral, metal ion-crosslinked ethylene-methacrylic acid copolymer, polyurethane, cellophane and the like. Preferably, polyester, polycarbonate, polymethyl methacrylate, acrylic resin, and the like are mentioned in terms of high resistance to loads during processing such as heat, solvent, and bending, and particularly high transparency, and more preferably excellent workability. Polyester is used. Among polyesters, polyethylene terephthalate is particularly preferable.

  The thickness of the substrate film is suitably in the range of 20 to 300 μm, preferably in the range of 50 to 250 μm, and more preferably in the range of 50 to 200 μm.

[Easily adhesive layer]
In the base film of the present invention, it is preferable that an easy adhesion layer is provided on at least the surface on which the high refractive index layer and the low refractive index layer are laminated. More preferably, the easy adhesion layer is laminated on both surfaces of the base film.

  The easy adhesion layer is preferably a layer containing a resin as a main component. That is, the resin content is preferably 50% by mass or more, more preferably 60% by mass or more, particularly preferably 70% by mass or more, and particularly preferably 80% by mass or more, based on 100% by mass of the total solid content of the easy-adhesion layer. The inclusion is most preferred. The upper limit is preferably 99% by mass or less, more preferably 98% by mass or less, and particularly preferably 95% by mass or less.

  As such a resin, a polyester resin, an acrylic resin, or a urethane resin is preferably used. Among these resins, a polyester resin is preferable, and a polyester resin having a naphthalene ring in the molecule is preferably used.

  The thickness of the easy-adhesion layer is preferably in the range of 10 to 300 nm, more preferably in the range of 15 to 200 nm, and particularly preferably in the range of 20 to 150 nm.

  The easy-adhesion layer is preferably laminated on the base film by a wet coating method. In particular, it is preferable that the easy-adhesion layer is laminated by a so-called “in-line coating method” in which the base film is laminated in the production process. When applying an easy-adhesion layer on a base film, corona discharge treatment, flame treatment, plasma treatment, etc. may be applied to the surface of the base film as a preliminary treatment for improving coatability and adhesion. preferable.

  Examples of the wet coating method include a reverse coating method, a spray coating method, a bar coating method, a gravure coating method, a rod coating method, a die coating method, a spin coating method, and an extrusion coating method.

[High refractive index layer]
In the present invention, the high refractive index layer has a refractive index of 1.60 to 1.80. The refractive index of the high refractive index layer is preferably in the range of 1.61 to 1.75, more preferably in the range of 1.62 to 1.70, and particularly preferably in the range of 1.63 to 1.68.

  The thickness of the high refractive index layer is preferably 20 nm or more, more preferably 25 nm or more, and particularly preferably 30 nm or more. The upper limit is preferably 80 nm or less, more preferably 70 nm or less, particularly preferably 60 nm or less, and most preferably 50 nm or less.

  The high refractive index layer contains a resin as a main component. Here, the high refractive index layer containing the resin as a main component means that the resin is contained in an amount of 60% by mass or more with respect to 100% by mass of the total solid content of the high refractive index layer. The content of the resin in the high refractive index layer is preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more with respect to 100% by mass of the total solid content of the high refractive index layer. The upper limit is preferably 99% by mass or less, and more preferably 98% by mass or less.

  As a high refractive index layer in a base film, a high refractive index layer (a high refractive index layer) having a relatively large amount of metal oxide fine particles having a high refractive index (metal oxide fine particles having an average particle diameter of 5 to 100 nm) has been conventionally used. Generally, 20 mass% or more of metal oxide fine particles are contained with respect to 100 mass% of the total solid content). However, when a high refractive index layer containing a relatively large amount of particles such as metal oxide fine particles is used, the base film obtained by laminating a low refractive index layer on the high refractive index layer is low. It becomes difficult to maintain the average roughness (Ra) of the refractive index layer surface below 1 nm.

  Therefore, the high refractive index layer contains particles such as metal oxide fine particles as long as the average roughness (Ra) of the surface of the low refractive index layer laminated on the high refractive index layer can be maintained below 1 nm. It is important to let From this viewpoint, the content when the high refractive index layer contains particles is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 1% by mass with respect to 100% by mass of the total solid content of the high refractive index layer. % Or less is preferable. Most preferably, the high refractive index layer contains substantially no particles. Here, that the high refractive index layer does not substantially contain particles means that particles are not intentionally added to the coating liquid for forming the high refractive index layer.

  In the present invention, the high refractive index layer contains a resin as a main component and has a refractive index of 1.60 to 1.80. Such a high refractive index layer can be realized by containing a high refractive index resin as a resin.

  The high refractive index layer is preferably a layer obtained by applying a thermosetting composition or an active energy ray curable composition by a wet coating method and curing the composition. In particular, a layer obtained by applying and curing an active energy ray-curable composition by a wet coating method is preferable. As the wet coating method, the above-described coating method can be used.

  Hereinafter, the active energy ray-curable composition containing a high refractive index resin will be described.

  Examples of the high refractive index resin include resins containing halogen atoms other than fluorine (for example, resins containing bromine atoms, resins containing chlorine atoms), resins containing sulfur atoms, resins containing nitrogen atoms, resins containing phosphorus atoms, silicon Examples thereof include a resin containing an atom and a resin containing an aromatic ring (for example, a resin containing a fluorene skeleton, a resin containing a phenyl group, etc.).

  Examples of resins containing halogen atoms other than fluorine (for example, resins containing bromine atoms and resins containing chlorine atoms) include brominated acrylic resins, brominated urethane resins, brominated polyester resins, brominated polyether resins, and brominated resins. Examples include epoxy resins, brominated spiroacetal resins, brominated polybutadiene resins, brominated polythiol polyene resins, chlorinated acrylic resins, chlorinated urethane resins, chlorinated polyester resins, chlorinated polyether resins, and chlorinated epoxy resins.

  Further, as a raw material component of a resin containing a bromine atom, for example, a compound obtained by brominating the ortho-para position of the phenyl group of acrylate can be used. These compounds can be obtained as commercial products. For example, there are BR-42, BR-42M, BR-30M, BR-31, etc. manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., RDX51027 manufactured by Daicel-Cytec.

  Further, as a resin containing a chlorine atom, a benzyl chloride salt of N, N-dimethylaminoethyl methacrylate or the like can be used.

  In the following description, “... (Meth) acrylate” includes both compounds of “... Acrylate” and “.

  Examples of the resin containing a sulfur atom include S, S′-ethylenebis (thio (meth) acrylate), S, S ′-(thiodiethylene) bis (thio (meth) acrylate), S, S ′-[thiobis ( Diethylene sulfide)] bis (thio (meth) acrylate), S, S ′-(oxydiethylene) bis (thio (meth) acrylate) and the like can be used. Here, thio (meth) acrylate includes both thiomethacrylate and thioacrylate.

  Among these, S, S′-ethylenebis (thiomethacrylate) and S, S ′-(thiodiethylene) bis (thiomethacrylate) are preferably used. S, S′-ethylenebis (thiomethacrylate) is obtained by reacting 1,2-ethanedithiol and an alkali metal salt of methacryloyl chloride obtained by reacting 1,2-ethanedithiol with an alkali metal compound in a nonpolar organic solvent. It can manufacture by the method of making it react with. As S, S ′-(thiodiethylene) bis (thiomethacrylate), those commercially available as trade name S2EG manufactured by Nippon Shokubai Co., Ltd. can be used.

  Examples of the resin containing a sulfur atom and an aromatic ring include S, S ′-(thiodi-p-phenylene) bis (thio (meth) acrylate), S, S ′-[4,4′-thiobis (3 -Chlorobenzene)] bis (thio (meth) acrylate), S, S '-[4,4'-thiobis (3,5-dichlorobenzene)] (thio (meth) acrylate), S, S'-[4, 4′-thiobis (3-bromobenzene)] (thio (meth) acrylate), S, S ′-[4,4′-thiobis (3,5-dibromobenzene)] (thio (meth) acrylate), S, S ′-[4,4′-thiobis (3-methylbenzene)] bis (thio (meth) acrylate), S, S ′-[4,4′-thiobis (3,5-dimethylbenzene)] (thio ( (Meth) acrylate), S, S ′-[4,4′-thiobis 3-methyl benzene)] bis (thio (meth) acrylate), or the like can be used. Of these, S, S ′-(thiodi-p-phenylene) bis (thiomethacrylate) (MPSMA manufactured by Sumitomo Seika Co., Ltd.) is preferably used, which is 4,4′-thiodibenzenethiol and an alkali metal compound. Can be produced by a method of reacting an alkali metal salt of 4,4′-thiodibenzenethiol obtained by reacting with methacryloyl chloride in a nonpolar organic solvent.

  As the resin containing an aromatic ring, an acrylic resin having a 9,9-bisphenoxyfluorene skeleton, an acrylic resin having a biphenyl group, an epoxy resin, or the like can be used. For example, 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene (NK ester A-BPEF), o-phenylphenol glycidyl ether acrylate (NK ester 401P), hydroxyethylated o-, manufactured by Shin-Nakamura Chemical Co., Ltd. Phenylphenol acrylate (NK ester A-LEN-10), 9,9-bis (3-methyl-4-hydroxyphenyl) fluorene (BCF), 9,9-bis [4- (2-hydroxyethoxy) manufactured by JFE Chemical Co., Ltd. ) Phenyl] fluorene (BPEF), bisphenol fluorenediglycidyl ether (BPFG), bisphenoxyethanol fluorenediglycidyl ether (BPFG), bisphenoxyethanol fluorenic acrylate (BPEF-A) manufactured by Osaka Gas Chemical Co., Ltd. Ogsol PG series, Ogsol EG series, Ogsol EA series, Ogsol EA-F series, Nagase Sangyo Co., Ltd. Oncoat EX series, Kyoeisha Chemical Co., Ltd. HIC-G series, ADEKA company RF (X) series, etc. can be used. .

  As exemplified above, the high refractive index resin is more preferably a polymerizable monomer or polymerizable oligomer containing a polymerizable functional group such as an acryl group, a methacryl group, a vinyl group, an allyl group, and an epoxy group.

  The active energy ray-curable composition preferably contains an active energy ray-curable resin in addition to the above-described high refractive index resin. Here, the active energy ray-curable resin is a resin that is polymerized and cured by irradiation with an active energy ray such as an electron beam or an ultraviolet ray, and such a resin is obtained from a polymerizable monomer or a polymerizable oligomer. .

  The polymerizable monomer or polymerizable oligomer is preferably a compound having two or more polymerizable functional groups (for example, an acryl group, a methacryl group, a vinyl group, an allyl group, etc.) in the molecule, and particularly three or more in the molecule. A compound having a polymerizable functional group is preferably used.

  Examples of the polymerizable monomer include neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (Meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaerythritol tri (meth) acrylate, Tripentaerythritol hexa (meth) triacrylate, trimethylolpropane (meth) acrylic acid benzoate, trimethylolpropane benzoate ester Polyfunctional acrylate etc., glycerin di (meth) acrylate hexamethylene diisocyanate, and urethane acrylates such as pentaerythritol tri (meth) acrylate hexamethylene diisocyanate.

  Examples of the polymerizable oligomer include polyester (meth) acrylate, polyurethane (meth) acrylate, epoxy (meth) acrylate, polyether (meth) acrylate, alkit (meth) acrylate, melamine (meth) acrylate, and silicone (meth). An acrylate etc. can be mentioned.

  The content of the high refractive index resin in the active energy ray-curable composition is preferably 40% by mass or more, more preferably 50% by mass or more, particularly preferably 100% by mass of the total solid content of the active energy ray-curable composition. 60 mass% or more is preferable. The upper limit is preferably 95% by mass or less, and preferably 90% by mass or less.

  The content of the polymerizable monomer or polymerizable oligomer used in combination with the high refractive index resin is preferably in the range of 5 to 60% by mass with respect to 100% by mass of the total solid content of the active energy ray-curable composition, and 10 to 50%. The range of mass% is more preferable, and the range of 15 to 40 mass% is particularly preferable.

  The active energy ray-curable composition preferably contains a photopolymerization initiator. Specific examples of such a photopolymerization initiator include acetophenone, 2,2-diethoxyacetophenone, p-dimethylacetophenone, p-dimethylaminopropiophenone, benzophenone, 2-chlorobenzophenone, 4,4′-dichloro. Benzophenone, 4,4′-bisdiethylaminobenzophenone, Michler's ketone, benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, methylbenzoyl formate, p-isopropyl-α-hydroxyisobutylphenone, α-hydroxyisobutylphenone, Carbonyl compounds such as 2,2-dimethoxy-2-phenylacetophenone and 1-hydroxycyclohexyl phenyl ketone, tetramethylthiuram monosulfide, Sulfur compounds such as tetramethylthiuram disulfide, thioxanthone, 2-chlorothioxanthone, and 2-methylthioxanthone can be used. These photopolymerization initiators may be used alone or in combination of two or more.

  The content of the photopolymerization initiator is suitably in the range of 0.1 to 10% by mass and in the range of 0.5 to 8% by mass with respect to 100% by mass of the total solid content of the active energy ray-curable composition. Is preferred.

[Low refractive index layer]
The low refractive index layer has a refractive index of 1.52 or less. The refractive index of the low refractive index layer is preferably 1.46 or less, more preferably 1.45 or less, and particularly preferably 1.43 or less. The lower limit is preferably 1.25 or more, and more preferably 1.30 or more.

  The thickness of the low refractive index layer is preferably 5 nm or more, and more preferably 10 nm or more. The upper limit is preferably 50 nm or less, and more preferably 40 nm or less.

  The low refractive index layer contains a resin as a main component. Here, the low refractive index layer containing a resin as a main component means that the resin is contained in an amount of 60% by mass or more with respect to 100% by mass of the total solid content of the low refractive index layer. The content of the resin in the low refractive index layer is preferably 70% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more with respect to 100% by mass of the total solid content of the low refractive index layer. The upper limit of the content is not particularly limited, and the resin content may be 100% by mass.

  As a low refractive index layer in the base film, a low refractive index layer that has conventionally contained a relatively large amount of low refractive index particles such as silica particles and magnesium fluoride particles (relative to the total solid content of 100% by mass of the low refractive index layer). In general, low-refractive-index particles are contained in an amount of 20% by mass or more).

  However, when a low refractive index layer containing a relatively large amount of such low refractive index particles is used, it is difficult to maintain the average roughness (Ra) of the surface of the low refractive index layer of the base film below 1 nm. . Therefore, it is important to contain particles within a range in which the average roughness (Ra) of the surface of the low refractive index layer can be maintained below 1 nm. From this viewpoint, the content of particles in the low refractive index layer is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 1% by mass or less, with respect to 100% by mass of the solid content of the low refractive index layer. . Most preferably, the low refractive index layer contains substantially no particles. Here, that the low refractive index layer does not substantially contain particles means that particles are not intentionally added to the coating liquid for forming the low refractive index layer.

  In the present invention, the low refractive index layer contains a resin as a main component and has a refractive index of 1.52 or less. Such a low refractive index layer can be realized by including a low refractive index resin as a resin.

  The low refractive index layer is preferably a layer obtained by applying a thermosetting composition or an active energy ray curable composition by a wet coating method and curing it. In particular, a layer obtained by applying and curing an active energy ray-curable composition by a wet coating method is preferable. As the wet coating method, the above-described coating method can be used.

  Hereinafter, the active energy ray-curable composition containing a low refractive index resin will be described.

  As the low refractive index resin, a fluorine-containing compound is preferably used. Examples of the fluorine-containing compound include fluorine-containing monomers, fluorine-containing oligomers, and fluorine-containing polymer compounds. Here, the fluorine-containing monomer and the fluorine-containing oligomer are monomers and oligomers having a fluorine atom and a polymerizable functional group (for example, acrylic group, methacryl group, vinyl group, allyl group, etc.) in the molecule.

  Examples of the fluorine-containing monomer and fluorine-containing oligomer include 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3,3-pentafluoropropyl (meth) acrylate, and 2- (perfluorobutyl). ) Ethyl (meth) acrylate, 2- (perfluorohexyl) ethyl (meth) acrylate, 2- (perfluorooctyl) ethyl (meth) acrylate, 2- (perfluorodecyl) ethyl (meth) acrylate, β- (per Fluoro-containing (meth) acrylic esters such as fluorooctyl) ethyl (meth) acrylate, di- (α-fluoroacrylic acid) -2,2,2-trifluoroethylethylene glycol, di- (α-fluoroacrylic acid) ) -2,2,3,3,3-pentafluoropropylethylene glycol, di (Α-fluoroacrylic acid) -2,2,3,3,4,4,4-hexafluorobutylethylene glycol, di- (α-fluoroacrylic acid) -2,2,3,3,4,4,4 5,5,5-nonafluoropentylethylene glycol, di- (α-fluoroacrylic acid) -2,2,3,3,4,4,5,5,6,6,6-undecafluorohexylethylene glycol , Di- (α-fluoroacrylic acid) -2,2,3,3,4,4,5,5,6,6,7,7,7-tridecafluoroheptylethylene glycol, di- (α-fluoro Acrylic acid) -2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctylethylene glycol, di- (α-fluoroacrylic acid) -3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 8-tridecafluorooctylethylene glycol, di- (α-fluoroacrylic acid) -2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9 , 9-heptadecafluorononylethylene glycol and the like di- (α-fluoroacrylic acid) fluoroalkyl esters.

  Examples of the fluorine-containing polymer compound include a fluorine-containing copolymer having a fluorine-containing monomer and a monomer for imparting a crosslinkable group as constituent units. Specific examples of the fluorine-containing monomer unit include, for example, fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole, etc. ), (Meth) acrylic acid partial or fully fluorinated alkyl ester derivatives (for example, Biscoat 6FM (manufactured by Osaka Organic Chemicals) and M-2020 (manufactured by Daikin)), fully or partially fluorinated vinyl ethers, and the like. As a monomer for imparting a crosslinkable group, in addition to a (meth) acrylate monomer having a crosslinkable functional group in the molecule like glycidyl methacrylate, it has a carboxyl group, a hydroxyl group, an amino group, a sulfonic acid group, etc. ) Acrylate monomers (for example, (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, etc.).

  The content of the fluorine-containing compound in the active energy ray-curable composition is preferably 20% by mass or more, more preferably 30% by mass or more, with respect to 100% by mass of the total solid content of the active energy ray-curable composition. A mass% or more is particularly preferred. The upper limit is preferably 98% by mass or less, more preferably 95% by mass or less, and particularly preferably 90% by mass or less.

  The active energy ray-curable composition preferably contains an active energy ray-curable resin in addition to the above-described low refractive index resin. Here, the active energy ray-curable resin is a resin that is polymerized and cured by irradiation with an active energy ray such as an electron beam or an ultraviolet ray, and such a resin is obtained from a polymerizable monomer or a polymerizable oligomer. .

  As the polymerizable monomer and polymerizable oligomer, the same compounds as the polymerizable monomer and polymerizable oligomer that can be contained in the high refractive index layer can be used.

  As the polymerizable monomer or polymerizable oligomer used in combination with the low refractive index resin, a compound having three or more polymerizable functional groups in one molecule is particularly preferably used.

  The content of the polymerizable monomer or polymerizable oligomer used in combination with the low refractive index resin is preferably in the range of 5 to 80% by mass with respect to 100% by mass of the total solid content of the active energy ray-curable composition, and 10 to 70%. The range of mass% is more preferable, and the range of 20 to 6 mass% is particularly preferable.

  The active energy ray-curable composition preferably contains a photopolymerization initiator. As the photopolymerization initiator, the same compound as the photopolymerization initiator that can be contained in the high refractive index layer can be used.

  The content of the photopolymerization initiator is suitably in the range of 0.1 to 10% by mass and in the range of 0.5 to 8% by mass with respect to 100% by mass of the total solid content of the active energy ray-curable composition. Is preferred.

  [Method of forming high refractive index layer and low refractive index layer].

  The method of applying and laminating one layer at a time by wet coating is a method in which a high refractive index layer is wet coated, dried and cured as necessary, and then a low refractive index layer is wet coated. It is a method of forming by drying and curing. The formation of the high refractive index layer and the low refractive index layer may be performed in separate steps or continuously in one step. The method of simultaneous multilayer coating by the wet coating method is a coating method capable of simultaneous multilayer coating, for example, a high refractive index layer and a low refractive index layer using a multilayer slot die coater, multilayer slide bead coater, extrusion type die coater, etc. Are simultaneously laminated and coated, and if necessary, dried and hardened.

[Hard coat layer]
In the base film of the present invention, a hard coat layer is preferably provided between the base film and the high refractive index layer. Furthermore, it is preferable to provide an easy-adhesion layer as described above between the base film and the hard coat layer.

  The thickness of the hard coat layer is preferably 0.5 μm or more, and more preferably 1 μm or more. The upper limit of the thickness is preferably 10 μm or less, more preferably 8 μm or less, further preferably 5 μm or less, and particularly preferably 3 μm or less.

  When a hard coat layer is provided, it is important that the average roughness (Ra) of the surface of the low refractive index layer is not inhibited from becoming less than 1 nm. That is, the hard coat layer surface needs to be relatively smooth.

  The hard coat layer preferably does not contain particles having an average particle size of 0.5 μm or more from the viewpoint of maintaining smoothness. The hard coat layer can contain particles having an average particle size of less than 0.5 μm, and the content thereof is 100% by mass of the solid content of the hard coat layer from the viewpoint of maintaining the smoothness of the hard coat layer. Is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 1% by mass or less.

  When providing an easily bonding layer between a base film and a hard-coat layer, the relationship of the refractive index of these layers is the refractive index of a base film> the refractive index of an easily-bonding layer> the refractive index of a hard-coat layer. It is preferable.

  In particular, the absolute values of the refractive index difference between the base film and the easy adhesion layer and the refractive index difference between the easy adhesion layer and the hard coat layer are each preferably 0.1 or less, more preferably 0.09 or less, and 0.08 or less. Is particularly preferred. The lower limit is preferably 0.03 or more, and more preferably 0.04 or more. Thereby, the uneven reflection color of the base film can be reduced.

  The refractive index of the hard coat layer is suitably in the range of 1.46 to 1.55, preferably in the range of 1.48 to 1.54, and more preferably in the range of 1.50 to 1.53.

  The hard coat layer can be colored by containing a coloring dye or a coloring pigment. Thereby, the reflective color and transparent color of a transparent conductive film can be adjusted.

  The hard coat layer is preferably a layer obtained by applying a thermosetting composition or an active energy ray curable composition by a wet coating method, drying it if necessary, and then curing it. In particular, it is preferable that the active energy ray-curable composition is a layer that is applied by a wet coating method, dried as necessary, and then cured. As the wet coating method, the above-described coating method can be used.

  The active energy ray-curable composition preferably contains a polymerizable monomer or a polymerizable oligomer. The active energy ray curable composition preferably contains a photopolymerization initiator.

  As the polymerizable monomer, the polymerizable oligomer, and the photopolymerization initiator, those similar to those used in the above-described high refractive index layer are used, and thus description thereof is omitted here.

  When the high refractive index layer and the low refractive index layer are provided only on one side of the base film, the opposite side of the base film (the side opposite to the side on which the high refractive index layer and the low refractive index layer of the base film are provided) It is preferable to provide a hard coat layer (back hard coat layer) containing particles on the surface. By providing such a back hard coat layer, the slipperiness and blocking resistance of the base film are improved.

  In particular, the back surface hard coat layer preferably contains organic particles having an average particle size of less than 0.5 μm, and further preferably contains organic particles having an average particle size of 0.05 to 0.3 μm. The content of the organic particles in the back hard coat layer is preferably 3% by weight or more with respect to 100% by weight of the total solid content of the back hard coat layer from the viewpoint of improving slipperiness and blocking resistance. Is more preferable, and 5 mass% or more is particularly preferable. The upper limit of the content of the organic particles is preferably 25% by mass or less, more preferably 20% by mass or less, and particularly preferably 15% by mass or less with respect to 100% by mass of the total solid content of the back surface hard coat layer.

As the resin constituting the organic particles, an acrylic resin, a styrene resin, a polyester resin, a polyurethane resin, a polycarbonate resin, a polyamide resin, a silicone resin, a fluorine resin, or 2 used for the synthesis of the above resin. Examples thereof include copolymer resins of more than one type of monomer. Among these, acrylic resin particles are preferably used. Here, acrylic resin particles are acrylic resin particles, methacrylic resin particles, acrylic monomers or methacrylic monomers and other monomers (for example, styrene, urethane acrylate, urethane methacrylate, polyester acrylate). , Polyester methacrylate, silicone acrylate, silicone methacrylate, etc.).

  Among the copolymer resin particles, styrene-acrylic copolymer resin particles such as styrene-acrylic copolymer resin particles and styrene-methacrylic copolymer resin particles are preferably used.

  These organic particles are preferably synthesized by an emulsion polymerization method, and organic particles having an average particle diameter of less than 0.5 μm can be obtained by synthesis by an emulsion polymerization method.

[Transparent conductive film for touch panel]
A transparent conductive film is obtained by providing a transparent conductive film on the low refractive index layer of the above-mentioned base film.

  As the touch panel, a resistive touch panel and a capacitive touch panel are mainstream, but the transparent conductive film of the present invention can be used for any touch panel. In particular, the transparent conductive film of the present invention is suitable for a capacitive touch panel.

  The transparent conductive film of the transparent conductive film of the capacitive touch panel is usually patterned in a predetermined pattern. The patterning of the transparent conductive film is performed by etching the transparent conductive film.

  A transparent conductive film having a patterned transparent conductive film has a pattern portion (a portion where the transparent conductive film remains without being etched (conductive portion)) and a non-pattern portion (the transparent conductive film is etched). The part of the pattern is visually recognized due to the difference in reflectance and transmittance from the removed part (non-conductive part) or the color tone of the pattern part and the non-pattern part, so-called “bone appearance” occurs. The visibility of the transparent conductive film is reduced. This “bone appearance” problem is reduced by using the base film of the present invention.

[Transparent conductive film]
As a material of the transparent conductive film, a known material used for a transparent conductive film can be used. Examples thereof include metal oxides such as tin oxide, indium oxide, antimony oxide, zinc oxide, ITO (indium tin oxide) and ATO (antimony tin oxide), metal nanowires such as silver nanowires, and carbon nanotubes. Among these, ITO is preferably used.

  The thickness of the transparent conductive film is preferably smaller from the viewpoint of improving the visibility of the transparent conductive film, specifically 40 nm or less, more preferably 30 nm or less, still more preferably 25 nm or less, and particularly preferably 20 nm or less. . The lower limit of the thickness of the transparent conductive film is preferably 5 nm or more, more preferably 7 nm or more, and particularly preferably 10 nm or more from the viewpoint of securing a low-resistance transparent conductive film.

  The surface resistance value of the transparent conductive film is preferably 1000Ω / □ or less, and preferably 500Ω / □ or less.

  The refractive index of the transparent conductive film is preferably 1.81 or more. Further, the refractive index of the transparent conductive film is preferably 1.85 or more, more preferably 1.90 or more. The upper limit is preferably 2.20 or less, and more preferably 2.10 or less.

  It does not specifically limit as a formation method of a transparent conductive film, A conventionally well-known method can be used. Specifically, for example, a dry process such as a vacuum deposition method, a sputtering method, or an ion plating method can be used.

  The transparent conductive film is preferably patterned. The patterning of a transparent conductive film can form various patterns according to the use to which a transparent conductive film is applied. Note that the pattern portion and the non-pattern portion are formed by patterning the transparent conductive film. Examples of the pattern shape of the pattern portion include a stripe shape, a lattice shape, or a combination thereof. Specifically, for example, there are patterns disclosed in JP-A-2006-344163, JP-A-2011-128896, and the like.

  The patterning of the transparent conductive film is generally performed by etching. For example, an etching resist film having a predetermined pattern is formed on the transparent conductive film by a photolithography method, a laser exposure method, or a printing method, and then etched to pattern the transparent conductive film.

  A conventionally well-known thing is used as an etching liquid. For example, inorganic acids such as hydrogen chloride, hydrogen bromide, sulfuric acid, nitric acid and phosphoric acid, organic acids such as acetic acid, and mixtures thereof, and aqueous solutions thereof are used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these Examples. In addition, the measuring method and evaluation method in a present Example are shown below.

[Measurement method and evaluation method]
(1) Refractive index measurement 1 (refractive index of easy-adhesion layer, high refractive index layer, low refractive index layer and hard coat layer)
About 25 degreeC temperature about the coating film (dry thickness of about 2 micrometers) which apply | coated and formed each coating composition of an easily bonding layer, a high refractive index layer, a low refractive index layer, and a hard-coat layer on a silicon wafer with a spin coater The refractive index of 589 nm was measured with a phase difference measurement device (Nikon Corporation: NPDM-1000) under the conditions.

(2) Measurement of refractive index 2 (refractive index of transparent conductive film)
A transparent conductive film is laminated on a PET film (polyethylene terephthalate film) having a known refractive index so as to have a thickness of 20 nm under the same conditions as the actual lamination conditions, thereby producing a sample for refractive index measurement. Next, the reflectance and thickness of the thin transparent conductive film of the sample for refractive index measurement are measured. The refractive index of the transparent conductive film is calculated from the reflectance, film thickness, and refractive index of the PET film thus obtained.

  The above reflectance is obtained by uniformly scratching the surface of the PET film opposite to the surface on which the transparent conductive film is laminated with a water resistant sandpaper of # 320 to 400, and then applying a black paint (black magic ink (registered trademark) solution). ), And the reflection from the opposite surface is completely eliminated, and the reflectance at 589 nm is measured using a spectrophotometer UV-3150 manufactured by Shimadzu Corporation.

(3) Refractive index measurement 3
The refractive index of the base film (PET film) was measured at 589 nm with an Abbe refractometer according to JIS K7105 (1981).

(4) Measurement of thickness of each layer and film A cross section of the sample was cut into ultra-thin sections, and at a magnification of 50,000 to 300,000 times with a transmission electron microscope (Hitachi H-7100FA type) at an acceleration voltage of 100 kV. The cross section of the sample was observed, and the thickness of each layer and film was measured. In addition, when the boundary of each layer was not clear, the dyeing | staining process was performed as needed.

(5) Evaluation of visibility ("bone appearance") of transparent conductive film pattern A sample was placed on a black plate, and whether or not the pattern portion could be visually confirmed was evaluated based on the following criteria. In the case of a sample in which a transparent conductive film was laminated only on one surface of the base film, evaluation was performed with the transparent conductive film on top. In the case of the sample in which the transparent conductive film was laminated on both surfaces of the base film, the transparent conductive film on each surface was placed on top, and each was evaluated.
A: A pattern part cannot be visually recognized.
B: A pattern part can be visually recognized slightly.
C: A pattern part can be visually recognized clearly.

(6) Measurement of surface resistance value The surface electrical resistance value (Ω / □) of the ITO film before pattern processing was measured using a four-terminal method (RC2175 manufactured by EDTM). An average value was calculated by measuring a total of five points at the four corners and the center of the 210 mm × 300 mm transparent conductive film.

(7) Measurement of average roughness (Ra) of low refractive index layer surface It measured using the following atomic force microscope (AFM) and analysis software. The measurement range is 1 μm square.
<Atomic microscope>"DIMENSION icon with Scan Asyst" manufactured by Bruker Corporation
<Analysis software> “Nano Scope Analysis (version1.40)” made by Bruker Corporation
[material]
<Coating liquid for easy adhesion layer formation (aqueous dispersion)>
In terms of solid content, Tg (glass transition temperature) of 120 ° C. is 26% by mass of polyester resin a, Tg is 80 ° C. of polyester resin b is 54% by mass, melamine-based crosslinking agent is 18% by mass, and particles are 2% by mass. % Was mixed to prepare an aqueous dispersion coating solution.
Polyester resin a: a polyester resin obtained by copolymerizing 43 mol% of 2,6-naphthalenedicarboxylic acid, 7 mol% of 5-sodium sulfoisophthalic acid, and 50 mol% of a diol component containing ethylene glycol.
Polyester resin b: a polyester resin obtained by copolymerizing 38 mol% of terephthalic acid, 12 mol% of trimellitic acid, and 50 mol% of a diol component containing ethylene glycol.
Melamine-based cross-linking agent: Methylol-based melamine cross-linking agent (“Nikalac MW12LF” manufactured by Sanwa Chemical Co., Ltd.)
Particles: colloidal silica having an average particle diameter of 190 nm.

<Active energy ray curable composition for hard coat layer formation>
(Composition A1)
58 parts by mass of dipentaerythritol hexaacrylate as a polymerizable monomer, 37 parts by mass of urethane acrylate oligomer (“UN-901T” from Negami Kogyo Co., Ltd .; containing 9 polymerizable functional groups in the molecule) as a polymerizable oligomer, light It was prepared by dispersing and dissolving 5 parts by mass of a polymerization initiator (“Irgacure (registered trademark) 184” manufactured by Ciba Specialty Chemicals) in an organic solvent (methyl isobutyl ketone).

(Composition A2)
87 parts by mass of dipentaerythritol hexaacrylate as a polymerizable monomer, and solid styrene-acrylic copolymer resin particles (trade name “STAPHYLOID EA-1135” manufactured by Ganz Kasei Co., Ltd .; average particle diameter of 130 nm) as organic particles are solid. It was prepared by dispersing and dissolving 8 parts by mass and 5 parts by mass of a photopolymerization initiator (“Irgacure 184” manufactured by Ciba Specialty Chemicals Co., Ltd.) in an organic solvent (methyl isobutyl ketone).

<Active energy ray-curable composition for forming a high refractive index layer>
(Composition B1)
95 parts by mass of a high refractive index resin (“X-12-2238” which is an ultraviolet curable resin manufactured by Shin-Etsu Chemical Co., Ltd.) and 5 parts by mass of a photopolymerization initiator (Irgacure 184 manufactured by Ciba Specialty Chemicals) are used as an organic solvent. It is a coating composition (active energy ray curable composition) dispersed or dissolved in (methyl isobutyl ketone).

(Composition B2)
60 parts by mass of a fluorene acrylic resin (“NK Ester A-BPEF” manufactured by Shin-Nakamura Chemical Co., Ltd.) as a high refractive index resin, 35 parts by mass of dipentaerythritol hexaacrylate as a polymerizable monomer, a photopolymerization initiator (Ciba 5 parts by mass of “Irgacure 184” manufactured by Specialty Chemicals Co., Ltd. was dispersed or dissolved in an organic solvent (methyl isobutyl ketone).

(Composition B3)
47 parts by mass of dipentaerythritol hexaacrylate as a polymerizable monomer, 50 parts by mass of zirconium oxide as metal oxide fine particles, and 3 parts by mass of a photopolymerization initiator (“Irgacure 184” manufactured by Ciba Specialty Chemicals) Was dispersed or dissolved in an organic solvent (methyl isobutyl ketone).

<Active energy ray-curable composition for forming a low refractive index layer>
(Composition C1)
60 parts by mass of dipentaerythritol pentaacrylate as a polymerizable monomer, 35 parts by mass of a fluorine-containing compound (fluorine resin “AR110” manufactured by Daikin Industries, Ltd.), photopolymerization initiator (Irgacure 184 manufactured by Ciba Specialty Chemicals) 5 It is a coating composition (active energy ray-curable composition) in which a part by mass is dispersed or dissolved in an organic solvent (a mixed solvent of methyl isobutyl ketone and propylene glycol monoethyl ether having a mass ratio of 1: 1).

(Composition C2)
80 parts by mass of β- (perfluorooctyl) ethyl acrylate as a fluorine-containing compound, 20 parts by mass of pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer as a polymerizable oligomer, and a photopolymerization initiator (2-methyl-1 [4- ( 5 parts by mass of methylthio) phenyl] -2-morpholinpropan-1-one) was prepared by dispersing or dissolving in an organic solvent (a mixed solvent of methyl isobutyl ketone and propylene glycol monoethyl ether in a mass ratio of 1: 1). .

(Composition C3)
As a polymerizable monomer, 81 parts by mass of dipentaerythritol pentaacrylate, 15 parts by mass of silica particles (hollow silica), and 4 parts by mass of a photopolymerization initiator (“Irgacure 184” manufactured by Ciba Specialty Chemicals Co., Ltd.) are used as an organic solvent. It was prepared by dispersing or dissolving in (isopropyl alcohol).

[Example 1]
A base film was prepared in the following manner.

<Preparation of easy adhesion layer laminated PET film>
A resin layer was in-line coated on both sides of a polyethylene terephthalate film (PET film) having a refractive index of 1.65 and a thickness of 100 μm within the PET film manufacturing process. That is, an easy-adhesion layer forming coating solution is applied to both sides of a PET film uniaxially stretched in the longitudinal direction by a bar coating method, dried at 100 ° C., then biaxially stretched in the width direction and heated at 230 ° C. for 20 seconds. The PET film in which the resin layer was laminated | stacked on both surfaces was processed and heat-cured. The resin layer had a refractive index of 1.59 and a thickness of 90 nm.

<Lamination of hard coat layer>
The composition A2 is applied by wet coating (gravure coating) to one surface (hereinafter sometimes referred to as “B surface”) of the easy-adhesion layer-laminated PET film prepared above, and dried at 90 ° C. Then, the hard coat layer (back surface hard coat layer) was formed by irradiating and curing ultraviolet rays. This hard coat layer had a thickness of 2 μmm and a refractive index of 1.52.

  Next, the composition A1 was applied to the other surface of the easy-adhesion layer-laminated PET film (hereinafter sometimes referred to as “A surface”) by a wet coating method (gravure coating method), dried at 90 ° C., A hard coat layer was formed by irradiating and curing ultraviolet rays. This hard coat layer had a thickness of 2 μmm and a refractive index of 1.52.

<Lamination of high refractive index layer>
On the hard coat layer formed using the composition A1, the composition B1 is applied by a wet coating method (gravure coating method), dried at 90 ° C., and then cured by irradiating with ultraviolet rays to form a high refractive index layer. Formed. The high refractive index layer had a refractive index of 1.65 and a thickness of 50 nm.

<Lamination of low refractive index layer>
A composition C1 is applied onto the high refractive index layer by a wet coating method (gravure coating method), dried at 90 ° C., irradiated with ultraviolet rays and cured to form a low refractive index layer, and a base film is formed. Created. The low refractive index layer had a refractive index of 1.45 and a thickness of 40 nm.

<Creation of transparent conductive film>
On the low refractive index layer of the base film created above, an ITO film is laminated as a transparent conductive film so as to have a thickness of 20 nm, and then only this ITO film is patterned into a lattice pattern (etching process) ) To obtain a transparent conductive film.

[Example 2]
A transparent conductive film was produced in the same manner as in Example 1 except that the composition of the low refractive index layer was changed to the composition C2. The low refractive index layer had a refractive index of 1.43 and a thickness of 40 nm.

[Example 3]
A transparent conductive film was produced in the same manner as in Example 1 except that the composition of the high refractive index layer was changed to the composition B2. The high refractive index layer had a refractive index of 1.62 and a thickness of 50 nm.

[Example 4]
A transparent conductive film was produced in the same manner as in Example 3 except that the composition of the low refractive index layer was changed to the composition C2. The low refractive index layer had a refractive index of 1.43 and a thickness of 40 nm.

[Comparative Example 1]
A transparent conductive film was produced in the same manner as in Example 1 except that the composition of the low refractive index layer was changed to the composition C3. The low refractive index layer had a refractive index of 1.43 and a thickness of 40 nm.

[Comparative Example 2]
A transparent conductive film was produced in the same manner as in Comparative Example 1 except that the composition of the high refractive index layer was changed to the composition B3. The high refractive index layer had a refractive index of 1.65 and a thickness of 50 nm.

[Comparative Example 3]
In Comparative Example 1, a transparent conductive film was produced in the same manner as in Comparative Example 1 except that the low refractive index layer was not laminated.

[Comparative Example 4]
In Comparative Example 2, a transparent conductive film was produced in the same manner as in Comparative Example 2 except that the low refractive index layer was not laminated.

[Comparative Example 5]
In Example 1, a transparent conductive film was prepared in the same manner as in Example 1 except that the low refractive index layer was directly laminated on the hard coat layer without laminating the high refractive index layer.

[Comparative Example 6]
In Comparative Example 1, a transparent conductive film was produced in the same manner as in Comparative Example 1 except that the low refractive index layer was directly laminated on the hard coat layer without laminating the high refractive index layer.

[Comparative Example 7]
In Comparative Example 1, a transparent conductive film was produced in the same manner as in Comparative Example 1 except that the transparent conductive film was directly laminated on the hard coat layer without laminating the high refractive index layer and the low refractive index phase. .

<Evaluation>
About each transparent conductive film produced above, the average roughness (Ra) of the surface of a low refractive index layer, the surface resistance value of a transparent conductive film, and the visibility of a transparent conductive film were evaluated. The results are shown in Table 1.

  As is clear from the results in Table 1, in the examples of the present invention, since the average roughness (Ra) of the surface of the low refractive index layer is extremely smooth as less than 1 nm, the surface of the transparent conductive film laminated thereon The resistance value is small. Moreover, the Example of this invention has the favorable pattern visibility of a transparent conductive film.

Claims (3)

On at least one surface of the substrate film, the refractive index is 1.60～ Ri 1.68 der, and the high refractive index layer and the refractive index thickness Ru der than 80nm or less 25nm is Ri der 1.52 or less, and containing as a main component a base film, respectively the high refractive index layer and the low refractive index layer is a resin of the touch panel transparent conductive film having a low refractive index layer Ru der than 50nm or less 5nm thickness in this order And the average roughness (Ra) of the surface of the said low-refractive-index layer is less than 1 nm, The base film of the transparent conductive film for touchscreens characterized by the above-mentioned.   The transparent conductive film for touchscreens which has a transparent conductive film on the low-refractive-index layer of the base film of the transparent conductive film for touchscreens of Claim 1. The transparent conductive film for touchscreens of Claim 2 with which the said transparent conductive film has a pattern part (conductive part) and a non-pattern part (non-conductive part).