JP2016137611A - Transparent laminated film and production method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent laminated film which has excellent antiblocking property and high light transmittance.SOLUTION: A transparent laminated film has a functional layer on one surface (A surface) of a substrate film and a back coat layer on the other surface (B surface) of the substrate film, in which the back coat layer is formed by layer separation of a coating layer into two layers of an upper side layer and a lower side layer, and an upper side layer containing silica particles is formed on the opposite side of the substrate film.SELECTED DRAWING: None

Description

  The present invention relates to a transparent conductive film for a touch panel, a base film of a transparent conductive film for a touch panel, a transparent laminated film applied to a protective film, an optical film, and the like of a display.

  Transparent conductive film for touch panel, base film for transparent conductive film for touch panel (for example, hard coat film and refractive index adjusting film), protective film for display (for example, hard coat film, antistatic film, antifouling film), or optical A film (for example, an antireflection film or an antiglare film) has various functional layers such as a conductive layer, a hard coat layer, a refractive index adjustment layer, an antireflection layer, an antistatic layer, and an antifouling layer on the base film. Is provided.

  Hereinafter, films provided with these various functional layers may be collectively referred to as “functional films”.

  It is known that the functional film described above is provided with a backcoat layer on the surface opposite to the surface on which the functional layer of the base film is provided (for example, Patent Documents 1 to 4). These back coat layers are provided for adjusting the curl balance of the functional film and preventing blocking.

JP 2005-18551 A JP 2005-266231 A JP 2008-310343 A JP 2010-107543 A

  In order to prevent blocking of the functional film, it is known that the back coat layer contains particles to form irregularities on the surface. By providing such a backcoat layer, the anti-blocking property is improved, but the light transmittance of the functional film tends to be lowered.

  Accordingly, an object of the present invention is to provide a transparent laminated film (functional film) having good anti-blocking properties and high light transmittance in view of the above-mentioned problems of the prior art.

The above object of the present invention has been basically achieved by the following invention.
[1] A transparent laminated film having a functional layer on one side (A side) of a base film and having a back coat layer on the other side (B side) of the base film, One coating layer is formed by separating the upper layer and the lower layer into two layers, and an upper layer containing silica particles is formed on the opposite side of the base film. A transparent laminated film.
[2] The transparent laminated film according to [1], wherein the coating layer contains at least a binder component and silica particles.
[3] The transparent laminated film according to [1] or [2], wherein the coating layer contains at least a binder component, silica particles, and metal oxide particles.
[4] The transparent laminated film according to any one of [1] to [3], wherein the silica particles are treated with a fluorine compound.
[5] The transparent laminated film according to any one of [1] to [4], wherein the silica particles are hollow silica particles.
[6] The transparent laminated film according to any one of [1] to [5], wherein the minimum reflectance of the upper layer surface is 2.0% or less.
[7] A method for producing a transparent laminated film having a functional layer on one side (A side) of a base film and having a backcoat layer on the other side (B side) of the base film, A step of laminating a backcoat layer, comprising a step of laminating a functional layer on one surface (A surface) of a material film and a step of laminating a backcoat layer on the other surface (B surface) of the base film The coating liquid containing at least the binder component, the silica particles treated with the fluorine compound and the solvent is applied once on the base film to form one coating layer, and the coating layer is separated into layers. An upper layer containing silica particles treated with a fluorine compound is formed on the opposite side of the base film, and a lower layer mainly composed of components other than silica particles is formed on the base film side. To see through Method for producing a laminated film.
[8] The method for producing a transparent laminated film according to [7], wherein the coating solution further contains metal oxide particles.

  According to the present invention, it is possible to provide a transparent laminated film having good anti-blocking properties and high light transmittance. According to the present invention, generation of interference fringes can be further suppressed.

  The transparent laminated film according to the present invention includes various functional films such as a transparent conductive film for a touch panel, a base film for a transparent conductive film for a touch panel (for example, a hard coat film or a refractive index adjusting film), and a protective film for a display (for example, It is applied to hard coat films, antistatic films, antifouling films), optical films (for example, antireflection films and antiglare films), and the like.

  The transparent laminated film concerning this invention has a functional layer in one side (A surface) of a base film, and has a backcoat layer in the other side (B surface) of a base film.

  A functional layer will not be specifically limited if it is a functional layer which comprises the above various functional films. Examples of the functional layer include a conductive layer, a hard coat layer, a refractive index adjusting layer, an antireflection layer, an antistatic layer, and an antifouling layer. The functional layer may be a single layer or a laminated structure of a plurality of layers. Examples of the laminated structure include a lamination of a hard coat layer and an antireflection layer, a lamination of a hard coat layer and a conductive layer, a lamination of a hard coat layer and a refractive index adjustment layer, a lamination of a refractive index adjustment layer and a conductive layer, Examples include lamination of an antireflection layer and an antifouling layer.

  The transparent laminated film according to the present invention has the main characteristics of the backcoat layer. That is, in the back coat layer of the present invention, one coating layer is separated into two layers, an upper layer (layer far from the base film) and a lower layer (layer closer to the base film). It is formed, The upper layer containing a silica particle is formed in the other side (far side from a base film) of a base film, It is characterized by the above-mentioned. By providing such a back coat layer, the anti-blocking property and transmittance of the transparent laminated film can be improved.

  The total light transmittance of the transparent laminated film according to the present invention is preferably as high as possible. Specifically, it is preferably 85% or more, more preferably 88% or more, and particularly preferably 90% or more.

  By providing the backcoat layer of the present invention, the reflectance of the surface (B surface) opposite to the functional layer of the transparent laminated film is reduced, and as a result, the transmittance of the transparent laminated film is increased. The smaller the reflectance of the backcoat layer surface (upper layer surface), the more preferable. Specifically, the minimum reflectance is preferably 2.0% or less, more preferably 1.5% or less, and 1.0% or less. Particularly preferred. By reducing the minimum reflectance of the backcoat layer surface (upper layer surface) to 2.0% or less, the transmittance of the transparent laminated film is improved. The lower limit is not particularly limited, but 0% is a substantial lower limit.

[Back coat layer]
The back coat layer according to the present invention has a layer separation structure. That is, the back coat layer of the present invention is formed by applying one coating layer on a substrate film and separating the coating layer into two layers, an upper layer and a lower layer. And the upper layer located in the other side (side far from a base film) of a base film is a layer containing a silica particle.

  A preferred embodiment (embodiment 1) of the backcoat layer of the present invention is formed by separating one coating layer containing at least a binder component and silica particles into two layers (an upper layer and a lower layer). There is to be.

  The back coat layer of the above aspect 1 is formed by, for example, coating a coating solution containing at least a binder component, silica particles, and a solvent once on a base film to form one coating layer, and drying the coating layer. In the process, it can be formed by moving silica particles to the opposite side (air side) of the base film. The back coat layer formed in this manner has a layer separation structure of an upper layer containing silica particles and a lower layer mainly composed of components other than silica particles (for example, a binder component).

  In another preferred embodiment (embodiment 2) of the backcoat layer of the present invention, at least one coating layer containing a binder component, silica particles and metal oxide particles is formed into two layers (an upper layer and a lower layer). It is to be formed by being separated.

  The back coat layer of the above aspect 2 is formed by, for example, applying a coating solution containing at least a binder component, silica particles, metal oxide particles and a solvent once on a base film to form one coating layer. In the drying process of this coating layer, it can form by moving a silica particle to the opposite side (air side) from a base film. The back coat layer thus formed has a layer separation structure of an upper layer containing silica particles and a lower layer mainly composed of components other than silica particles (for example, binder components and metal oxide particles).

  It is important that the back coat layer of the present invention is separated so that the upper layer and the lower layer form a clear interface. Thereby, the reflectance on the surface of the backcoat layer is lowered, and the transmittance of the transparent laminated film is improved. Whether the upper layer and the lower layer are separated by a clear interface can be confirmed by observing the cross section of the backcoat layer with a transmission electron microscope (TEM).

  The back coat layer in which the upper layer and the lower layer are formed by layer separation from one coating layer has an effect of further suppressing the generation of interference fringes. This is because the interface between the upper layer and the lower layer formed by layer separation is slightly uneven compared to the interface between the upper layer and the lower layer when the upper layer and the lower layer are separately coated. It is presumed that interference fringes are suppressed due to the relatively large number of structures.

  The above aspect 2 is preferable for the backcoat layer of the present invention from the viewpoint of reducing the reflectance of the backcoat layer surface and increasing the transmittance of the transparent laminated film.

  Since the upper layer formed by the layer separation of the present invention has a structure in which silica particles are arranged relatively densely, it is considered that antiblocking properties and transmittance are improved.

  From the above viewpoint, the volume ratio of the silica particles is preferably high in the upper layer in the backcoat layer of the present invention. The volume ratio of the silica particles in the upper layer can be represented, for example, by the ratio of the cross-sectional area of the silica particles to the arbitrary cross-sectional area of the upper layer (hereinafter referred to as the area ratio of the silica particles). The area ratio of the silica particles is preferably 50% or more, more preferably 60% or more, and particularly preferably 70% or more.

  By increasing the area ratio of the silica particles in the upper layer, the anti-blocking property of the transparent laminated film is improved, and the reflectance of the back coat layer surface (upper layer surface) is lowered to improve the transmittance of the transparent laminated film. .

  If the area ratio of the silica particles becomes too high, the silica particles may fall off due to a decrease in the film strength of the upper layer, or the scratch resistance of the upper layer may decrease. The upper limit is preferably 97% or less, and more preferably 95% or less.

  Here, when a silica particle is a hollow silica, the hollow part of a hollow silica is contained in the cross-sectional area of a silica particle.

  As described in the first and second embodiments, the backcoat layer according to the present invention includes at least one binder layer and silica particles (the second embodiment further contains metal oxide particles). It is formed by layer separation, and most of the silica particles in the coating layer move to the surface side (air side) upon completion of layer separation to form an upper layer, and in the lower layer The component other than the silica particles, that is, the binder component, the metal oxide particles and the like remain as the main components. A binder component is also present in the upper layer, and this binder component is present between the silica particles and the silica particles or in the vicinity of the interface between the upper layer and the lower layer and functions as a binder.

  Even if the layer separation is completed, it is assumed that some silica particles remain in the lower layer, but the content ratio of the silica particles in the lower layer is preferably small. When a relatively large amount of silica particles are present in the lower layer, the transmittance of the transparent laminated film may not be sufficiently improved. Specifically, the area ratio of silica particles in the lower layer (synonymous with the area ratio of silica particles in the upper layer) is preferably 15% or less, more preferably 10% or less, and particularly preferably 5% or less. The lower limit is not particularly limited, but 0% is a substantial lower limit.

  The lower layer is preferably a layer mainly composed of a binder component and / or metal oxide particles. That is, the lower layer includes an embodiment in which one of the binder component and the metal oxide particles is a main component, and an embodiment in which the total of the binder and the metal oxide particles is a main component.

  In the above-mentioned aspect 1, it is preferable that the lower layer mainly composed of the binder component is formed, and in the aspect 2, the lower layer mainly composed of the binder component and the metal oxide particles is formed. It is preferable.

  In the first aspect, in order to form the lower layer containing the binder component as a main component, the silica particles are removed from the total solid content (mass) of one coating layer before the upper layer and the lower layer are separated. The ratio (B1 / A1 × 100) of the mass (B1) of the binder component to the mass (A1) is preferably 50% by mass or more, and more preferably 60% by mass or more.

  In the above aspect 2, in order to form the lower layer mainly composed of the binder component and the metal oxide particles, the total solid content of one coating layer before the upper layer and the lower layer are separated ( The ratio (B2 / A2 × 100) of the total mass (B2) of the binder component and the metal oxide particles to the mass (A2) excluding the silica particles from the mass) is preferably 50% by mass or more, and 60% by mass The above is more preferable, and 70% by mass or more is preferable.

  The upper limit of the ratio in the first and second embodiments is not particularly limited, but is preferably 99% by mass or less, more preferably 97% by mass or less, and particularly preferably 95% by mass or less.

  The thickness of the upper layer in the backcoat layer of the present invention is preferably in the range of 60 to 150 nm, more preferably in the range of 70 to 130 nm, and more preferably in the range of 80 to 120 nm from the viewpoint of improving the transmittance and antiblocking property of the transparent laminated film. The range of is particularly preferable.

  The thickness of the lower layer in the backcoat layer of the present invention is preferably 80 nm or more, more preferably 100 nm or more from the viewpoint of improving the transmittance and scratch resistance of the transparent laminated film and suppressing oligomer precipitation from the base film. Preferably, 200 nm or more is more preferable, and 300 nm or more is particularly preferable. If the thickness of the lower layer becomes too large, the layer separation structure may be difficult to be formed. Therefore, the upper limit thickness is preferably 2000 nm or less, more preferably 1500 nm or less, and particularly preferably 1000 nm or less.

  The back coat layer of the present invention provides good anti-blocking properties even when the surface roughness Ra is relatively small as compared with the conventional back coat layer. By making the surface roughness of the backcoat layer relatively small, the transmittance of the transparent laminated film can be improved.

  The surface roughness Ra of the backcoat layer surface is preferably 15 nm or less, more preferably 12 nm or less, and particularly preferably 10 nm or less. The lower limit of the surface roughness Ra is preferably 3 nm or more, and particularly preferably 5 nm or more from the viewpoint of ensuring good blocking properties.

[Components of back coat layer]
As described above, the backcoat layer according to the present invention may be formed by separating one coating layer containing at least a binder component and silica particles into two layers (an upper layer and a lower layer). Preferably (Aspect 1), at least one coating layer containing at least a binder component, silica particles, and metal oxide particles is formed by separating the layers into two layers (an upper layer and a lower layer). Preferred (Aspect 2).

  As silica particles, hollow silica particles, porous silica particles, and colloidal silica (solid silica with respect to hollow silica) are preferably used. Here, the hollow silica particles are silica particles having cavities inside the particles, and the porous silica particles are silica particles having pores on the surface and inside of the particles. Among these silica particles, hollow silica is particularly preferable from the viewpoint of improving the transmittance of the transparent laminated film.

  The average particle diameter of the silica particles is preferably in the range of 10 to 120 nm, more preferably in the range of 20 to 100 nm, and particularly preferably in the range of 30 to 80 nm. When the average particle diameter of the silica particles is less than 10 nm, the antiblocking property may not be sufficiently improved. When the average particle diameter of the silica particles is larger than 120 nm, the transmittance of the transparent laminated film may not be sufficiently improved, and a layer separation structure may not be formed.

  The silica particles are preferably treated with a fluorine compound. Since the surface-free energy of the fluorine-treated silica particles becomes small, the silica particles easily move to the air side (the side opposite to the base film), and a layer separation structure is easily formed.

  The treatment of silica particles with a fluorine compound refers to a treatment in which the silica particles are chemically modified and a fluorine compound is introduced into the silica particles. The treatment of the silica particles with the fluorine compound may be performed in one stage or in multiple stages. Further, the fluorine compound may be used in a plurality of treatment stages, or the fluorine compound may be used in only one treatment stage. Here, “introduction” means that a fluorine compound is chemically bonded (including covalent bond, hydrogen bond, ionic bond, van der Waals bond, hydrophobic bond, etc.) or adsorbed (including physical adsorption and chemical adsorption) to silica particles. Refers to the state.

  As such a fluorine compound, a compound represented by the following general formula (I) is preferably used.

R ¹ -R ² -R ^f ... General formula (I)
Here, R ^f represents a fluoroalkyl group, R ¹ represents a reactive site, and R ² represents an alkylene group having 1 to 6 carbon atoms or an ester structure derived therefrom. Each may have a side chain in the structure.

  A fluoroalkyl group is a group in which part or all of hydrogen in an alkyl group is replaced with fluorine, and is a group mainly composed of fluorine atoms and carbon atoms.

  A reactive site refers to a site that reacts with other components by external energy such as heat or light. As such a reactive site, from the viewpoint of reactivity, alkoxysilyl group, silanol group in which alkoxysilyl group is hydrolyzed, silyl ether group, carboxyl group, hydroxyl group, epoxy group, vinyl group, allyl group, acryloyl group, And a methacryloyl group. Among these, an alkoxysilyl group, a silanol group, a silyl ether group, an epoxy group, an acryloyl group, and a methacryloyl group are preferable.

One of the treatment methods for introducing this fluorine compound is at least one fluoroalkoxysilane compound in which R ¹ in the general formula (I) is an alkoxysilyl group, silanol group, or silyl ether group, and silica particles or silica. In this method, the particle dispersion is mixed with a solvent, a catalyst, etc., and heated or dealcoholized in some cases to condense with the hydroxyl groups on the surface of the silica particles. The treatment of the silica particles with the fluorine compound is preferably performed in the form of a silica particle dispersion from the viewpoint of performing the silica particles in a finely dispersed state.

  The silica particle dispersion as used herein refers to a state in which the silica particles are dispersed in a solvent, and is sometimes referred to as a sol, suspension, slurry, colloidal solution. In addition to the silica particles and the solvent, a dispersant, A stabilizer, a surface treatment agent, and the like may be included.

  Specific examples of the fluorine compound described above include 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, 3,3,3-trifluoropropyltriisopropoxysilane, 3,3,3-trifluoropropyltrichlorosilane, 3,3,3-trifluoropropyltriisocyanate silane, 2-perfluorooctyltrimethoxysilane, 2-perfluorooctylethyltriethoxysilane, 2-perfluorooctylethyl Examples include triisopropoxysilane, 2-perfluorooctylethyltrichlorosilane, and 2-perfluorooctyl isocyanate silane.

  As another method for treating silica particles with a fluorine compound, a method in which silica particles or a silica particle dispersion is treated with a silane compound having no fluorine atom and then treated with a fluorine compound to join the silane compound and the fluorine compound together. There is.

  This silane compound is preferably a compound represented by the following general formula (II).

_{^{R 3 -R 4 -SiR 5 n2 (}} OR 6) 3-n2 general formula (II)
In the general formula (II), R ³ represents a reactive site, R ⁴ represents an alkylene group having 1 to 6 carbon atoms or an ester structure derived therefrom, and R ⁵ and R ⁶ represent hydrogen or carbon number, respectively. Represents an alkyl group of 1 to 4, and n2 represents an integer of 0 to 2.

Examples of the reactive site represented by R ³ include a vinyl group, an allyl group, an acryloyl group, and a methacryloyl group.

  Specific examples of the compound represented by the general formula (II) include acryloxyethyltrimethoxysilane, acryloxypropyltrimethoxysilane, acryloxybutyltrimethoxysilane, acryloxypentyltrimethoxysilane, and acryloxyhexyltrimethoxysilane. , Acryloxyheptyltrimethoxysilane, methacryloxyethyltrimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxybutyltrimethoxysilane, methacryloxyhexyltrimethoxysilane, methacryloxyheptyltrimethoxysilane, methacryloxypropylmethyldimethoxysilane, Including methacryloxypropylmethyldimethoxysilane and compounds in which the methoxy group in these compounds is substituted with other alkoxyl groups and hydroxyl groups And the like.

In addition, as the fluorine compound used in this treatment (treated with a silane compound and then treated with a fluorine compound), among the compounds represented by the general formula (I), the reactive site represented by R ¹ Are preferably vinyl, allyl, acryloyl, or methacryloyl.

  Specific examples of such fluorine compounds include 2,2,2-trifluoroethyl acrylate, 2,2,3,3,3-pentafluoropropyl acrylate, 2-perfluorobutylethyl acrylate, 3-perfluorobutyl- 2-hydroxypropyl acrylate, 2-perfluorohexylethyl acrylate, 3-perfluorohexyl-2-hydroxypropyl acrylate, 2-perfluorooctylethyl acrylate, 3-perfluorooctyl-2-hydroxypropyl acrylate, 2-perfluoro Decyl ethyl acrylate, 2-perfluoro-3-methylbutyl ethyl acrylate, 3-perfluoro-3-methoxybutyl-2-hydroxypropyl acrylate, 2-perfluoro-5-methylhexyl ethyl acetate 3-perfluoro-5-methylhexyl-2-hydroxypropyl acrylate, 2-perfluoro-7-methyloctyl-2-hydroxypropyl acrylate, tetrafluoropropyl acrylate, octafluoropentyl acrylate, dodecafluoroheptyl acrylate, hexa Decafluorononyl acrylate, hexafluorobutyl acrylate, 2,2,2-trifluoroethyl methacrylate, 2,2,3,3,3-pentafluoropropyl methacrylate, 2-perfluorobutylethyl methacrylate, 3-perfluorobutyl- 2-hydroxypropyl methacrylate, 2-perfluorooctylethyl methacrylate, 3-perfluorooctyl-2-hydroxypropyl methacrylate, 2-par Fluorodecylethyl methacrylate, 2-perfluoro-3-methylbutylethyl methacrylate, 3-perfluoro-3-methylbutyl-2-hydroxypropyl methacrylate, 2-perfluoro-5-methylhexylethyl methacrylate, 3-perfluoro- 5-methylhexyl-2-hydroxypropyl methacrylate, 2-perfluoro-7-methyloctylethyl methacrylate, 3-perfluoro-7-methyloctylethyl methacrylate, tetrafluoropropyl methacrylate, octafluoropentyl methacrylate, octafluoropentyl methacrylate, Dodecafluoroheptyl methacrylate, hexadecafluorononyl methacrylate, 1-trifluoromethyltrifluoroethyl methacrylate, hex Examples include safluorobutyl methacrylate.

  As the binder component, an active energy ray curable resin is preferably used. The active energy ray-curable resin is a resin that is polymerized and cured by active energy rays such as ultraviolet rays and electron beams, and the active energy ray-curable resin includes at least one ethylenically unsaturated group in the molecule. The compound (monomer and oligomer) which has. Here, examples of the ethylenically unsaturated group include acryloyl group, methacryloyl group, acryloyloxy group, methacryloyloxy group, allyl group, and vinyl group.

  In the following description, “... (Meth) acrylate” is a general term for “... Acrylate” and “.

  Examples of the compound having at least one ethylenically unsaturated group in the molecule include methyl (meth) acrylate, lauryl (meth) acrylate, ethyldiethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol ( (Meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) ) Acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, dipropylene glycol (Meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, glycerin propoxy Tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, di Pentaerythritol hexa (meth) acrylate, tripentaerythritol tri (meth) acrylate, tripenta Listylitol hexa (meth) acrylate, pentaerythritol tri (meth) acrylate hexamethylene diisocyanate urethane pre-oligomer, pentaerythritol tri (meth) acrylate-toluene diisocyanate urethane oligomer, pentaerythritol tri (meth) acrylate-isophorone diisocyanate urethane oligomer It is done.

  As the active energy ray-curable resin, a compound having 2 or more ethylenically unsaturated groups in the molecule is preferable, and a compound having 3 or more ethylenically unsaturated groups in the molecule is preferably used.

  As the metal oxide particles, metal oxide particles having a refractive index of 1.65 or more are preferable, and metal oxide particles having a refractive index of 1.7 to 2.8 are particularly preferably used.

  Examples of the metal oxide particles having a refractive index of 1.7 to 2.8 include titanium oxide, zirconium oxide, zinc oxide, tin oxide, antimony oxide, cerium oxide, iron oxide, zinc antimonate, and tin oxide doped indium oxide. (ITO), antimony-doped tin oxide (ATO), phosphorus-doped tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, fluorine-doped tin oxide, and the like. These metal oxide particles may be used alone, Two or more may be used together. Among the metal oxide particles, titanium oxide and zirconium oxide are particularly preferable because the refractive index of the lower layer can be increased without reducing transparency. By increasing the refractive index of the lower layer, the reflectance of the upper layer surface is lowered and the transmittance of the transparent laminated film is increased.

[Formation of layer separation structure]
The backcoat layer according to the present invention is a coating layer obtained by coating a coating solution containing at least a binder component, silica particles (silica particles treated with a fluorine compound) and a solvent on a substrate film once. Is preferably formed by layer separation. The coating solution preferably further contains metal oxide particles.

  The coating layer obtained by coating on the base film has silica particles with a small surface energy (silica particles treated with a fluorine compound) due to the difference in surface energy of components contained in the coating layer during the drying process. The upper layer containing silica particles is formed on the opposite side of the base film, and at the same time, components other than the silica particles in the coating layer (binder component and metal oxide) A lower layer mainly composed of particles or the like is formed on the base film side.

  The coating liquid for forming the backcoat layer is preferably a liquid in which at least a binder component and silica particles are dissolved or dispersed in a solvent. The coating solution preferably further contains metal oxide particles. The solvent is not particularly limited, but an organic solvent is preferably used. Examples of the organic solvent include methyl alcohol, ethyl alcohol, isopropyl alcohol, butyl alcohol, ethylene glycol, ethylene glycol monobutyl ether, propylene glycol, pyropyrene glycol monomethyl ether, cyclohexane, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, and ethyl acetate. , Butyl acetate, dimethylformamide and the like.

  In the coating solution for forming the backcoat layer, the content of the binder component, silica particles, and metal oxide particles is mainly the thickness of the upper layer mainly composed of silica particles, the binder and / or metal oxide particles. It adjusts suitably according to the thickness and refractive index of the lower layer used as a component.

  The content of the silica particles in the coating solution is adjusted according to the thickness design of the upper layer mainly composed of silica particles. The thickness of the upper layer is as described above.

  Content of the binder component and metal oxide particle in a coating liquid is adjusted according to the thickness and refractive index design of the lower layer which have a binder component and / or metal oxide particle as a main component. The thickness of the lower layer is as described above.

  The refractive index of the lower layer is preferably in the range of 1.50 to 1.80 from the viewpoint of increasing the transmittance of the transparent laminated film by reducing the reflectance of the upper layer surface.

  The refractive index of the upper layer containing silica particles as a main component is usually less than 1.50. By increasing the refractive index difference between the refractive index of the lower layer and the refractive index of the upper layer, the reflection of the upper layer surface is increased. The rate can be reduced. The refractive index of the upper layer is preferably less than 1.50, more preferably 1.48 or less, and particularly preferably 1.40 or less. The lower limit refractive index of the upper layer is not particularly limited, but is practically about 1.20.

  In this respect, the refractive index of the lower layer is preferably 1.53 or more, more preferably 1.55 or more, and particularly preferably 1.60 or more. If the refractive index of the lower layer becomes too high, interference fringes are likely to occur. Therefore, the upper limit refractive index is preferably 1.80 or less, more preferably 1.75 or less, and particularly preferably 1.70 or less.

  As described above, the refractive index of the lower layer is increased by containing metal oxide particles having a refractive index of 1.65 or more. That is, the refractive index of the lower layer can be increased by increasing the content ratio of the metal oxide particles in the coating solution.

  The back coat layer is preferably formed by applying a coating solution for forming the back coat layer on the substrate film, drying it, and then irradiating it with an active energy ray (particularly preferably ultraviolet rays) to cure.

  In order to sufficiently complete the layer separation, it is preferable to perform drying after coating gently. That is, it is preferable to carry out in two stages of low temperature drying and high temperature drying. Specifically, it is preferable to combine low temperature drying below 60 ° C. and high temperature drying above 60 ° C.

When an active energy ray-curable resin is used as the binder component, the active energy ray (ultraviolet ray) is irradiated and cured after drying. The dose of ultraviolet rays is preferably from 50 mJ / cm ² or more, 100 mJ / cm ² or more, and particularly 150 mJ / cm ² or more. The upper limit is preferably 2000 mJ / cm ² or less, and more preferably 1000 mJ / cm ² or less.

  In order to promote curing of the backcoat layer by ultraviolet irradiation, the coating solution preferably contains a photopolymerization initiator.

  Specific examples of such photopolymerization initiators include, for example, acetophenone, 2,2-diethoxyacetophenone, p-dimethylacetophenone, p-dimethylaminopropiophenone, benzophenone, 2-chlorobenzophenone, 4,4′-dichlorobenzophenone, 4,4′-bisdiethylaminobenzophenone, Michler's ketone, benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, methyl benzoylformate, p-isopropyl-α-hydroxyisobutylphenone, α-hydroxyisobutylphenone, 2, Carbonyl compounds such as 2-dimethoxy-2-phenylacetophenone and 1-hydroxycyclohexyl phenyl ketone, tetramethylthiuram monosulfide, teto Sulfur compounds such as lamethylthiuram disulfide, thioxanthone, 2-chlorothioxanthone, and 2-methylthioxanthone can be used. These photopolymerization initiators may be used alone or in combination of two or more.

  Moreover, generally the photoinitiator is marketed and they can be used. For example, Irgacure 184, Irgacure 907, Irgacure 379, Irgacure 819, Irgacure 127, Irgacure 500, Irgacure 754, Irgacure 250, Irgacure 1800, Irgacure 1870, Irgacure OXE01, DAROC OXERO 73 SPEEDCURE MBB, SPEEDCURE PBZ, SPEEDCURE ITX, SPEEDCURE CTX, SPEEDCURE EDB, XE Y, AC KY150, EAC Examples include KAYACURE DMBI.

  In addition to the fluorine compound for treating the silica particles with the fluorine compound, the coating liquid for forming the backcoat layer is preferably added with a fluorine compound as an additive and present in the coating liquid. Hereinafter, the fluorine compound added to the coating solution as an additive may be referred to as a fluorine compound (B). By including the fluorine compound (B) in the coating solution, formation of a layer separation structure is further promoted.

  As the fluorine compound (B), the same compound as the fluorine compound for treating the silica particles described above can be used.

  It does not specifically limit as a coating method for apply | coating the coating liquid for forming a backcoat layer on a base film, A well-known coating method can be used. Examples thereof include a gravure coating method, a die coating method, a dip coating method, a roll coating method, a spin coating method, and an extrusion coating method.

[Base film]
Although the material of the base film in the present invention is not particularly limited, examples of the material include polyester (for example, polyethylene terephthalate (PET), polybutylene terephthalate, polyethylene naphthalate, etc.), 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, etc. . 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 backcoat layer is laminated. When the easy adhesion layer is interposed between the base film and the back coat layer, the adhesion between the base film and the back coat layer is improved.

  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 200 nm, more preferably in the range of 15 to 150 nm, and particularly preferably in the range of 20 to 120 nm.

  When a polyethylene terephthalate film is used as the base film, the refractive index of the easy adhesion layer is preferably in the range of 1.55 to 1.70, from the viewpoint of suppressing interference fringes on the backcoat layer side, and 1.57. The range of ˜1.66 is more preferable, and the range of 1.58 to 1.65 is particularly preferable.

  In order to adjust the refractive index of the easy-adhesion layer to the above range, it is preferable to use a polyester resin having a naphthalene ring or a polyester resin having a fluorene ring as the resin. Moreover, the refractive index of an easily bonding layer can be adjusted to the said range by containing the metal oxide particle whose refractive index mentioned above is 1.65 or more.

[Hard coat layer]
The transparent laminated film concerning this invention can provide a hard-coat layer between a base film and a backcoat layer.

  When the thickness of the lower layer constituting the back coat layer is less than 80 nm, it is preferable to provide a hard coat layer between the base film and the back coat layer from the viewpoint of imparting good scratch resistance. .

  In this case, the thickness of the hard coat layer is preferably in the range of 0.3 to 5 μm, more preferably in the range of 0.5 to 4 μm, and particularly preferably in the range of 0.8 to 3 μm. The hard coat layer preferably has a pencil hardness of H or higher, more preferably 2H or higher. The upper limit is about 9H. The pencil hardness is measured according to JIS K5600-5-4 (1999). A hard coat layer can make pencil hardness H or more by using the above-mentioned active energy ray hardening resin.

[Functional film to which the transparent laminated film of the present invention is applied]
The transparent laminated film according to the present invention includes various functional films such as a transparent conductive film for a touch panel, a base film for a transparent conductive film for a touch panel (for example, a hard coat film or a refractive index adjusting film), and a protective film for a display (for example, It is applied to hard coat films, antistatic films, antifouling films), optical films (for example, antireflection films and antiglare films), and the like.

  The transparent laminated film of this invention is suitable for the base film of the transparent conductive film for touch panels in which high transmittance | permeability is requested | required among said functional films, and the transparent conductive film for touch panels.

[Functional layer]
The functional layer may be a layer having a function suitable for various functional films as described above. Examples of the functional layer include a conductive layer, a hard coat layer, a refractive index adjusting layer, an antireflection layer, an antistatic layer, and an antifouling layer. In the present invention, the functional layer preferably includes one or more layers selected from the group consisting of a conductive layer, a hard coat layer, a refractive index adjusting layer, an antireflection layer, an antistatic layer and an antifouling layer. More preferably, the functional layer includes one or more layers selected from the group consisting of a conductive layer, a hard coat layer, a refractive index adjusting layer, an antireflection layer, and an antistatic layer. More preferably, the functional layer includes one or more layers selected from the group consisting of a conductive layer, a hard coat layer, and a refractive index adjusting layer. Here, examples of the refractive index adjusting layer include a high refractive index layer and / or a low refractive index layer.

  In addition, the functional layer may be a single layer or may have a multilayer structure. Examples of the laminated structure include a laminated structure of a hard coat layer and an antireflection layer, a laminated structure of a hard coat layer and a conductive layer, a laminated structure of a hard coat layer and a refractive index adjusting layer, and a refractive index adjusting layer and a conductive layer. And a laminated structure of an antireflection layer and an antifouling layer.

  The transparent laminated film of the present invention is suitable for a transparent conductive film for a touch panel. Moreover, the transparent laminated film of this invention is suitable also for the base film of the transparent conductive film for touchscreens. Hereinafter, although the functional layer which comprises these functional films is demonstrated, this invention is not limited to these.

  When using the transparent laminated film of this invention as a transparent conductive film for touch panels, it has at least a conductive layer as a functional layer. As a material of the conductive layer, a known material used for an electrode of a touch panel 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 conductive layer is preferably 8 nm or more, more preferably 10 nm or more, and particularly preferably 15 m or more, from the viewpoint of ensuring good conductivity with a surface resistance value of 10 ³ Ω / □ or less, for example. Preferably there is. On the other hand, if the thickness of the conductive layer becomes too large, there may be a disadvantage that the transparency is lowered. Therefore, the upper limit of the thickness of the conductive layer is preferably 60 nm or less, more preferably 50 nm or less, and particularly preferably 40 nm or less. . The lower limit value of the surface resistance value of the surface conductive layer is not particularly limited, but 0Ω / □ is a substantial lower limit.

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

  The conductive layer formed as described above may be patterned. The conductive layer of the transparent conductive film for a capacitive touch panel is usually patterned into a predetermined pattern.

  On the other hand, when using the transparent laminated film of this invention as a base film of the transparent conductive film for touchscreens, the base film of the transparent conductive film for touchscreens points out the film before an above-described conductive layer is laminated | stacked. In this base film, the transparent conductive film for touch panel is provided with scratch resistance, the color of the conductive layer is adjusted, or the pattern portion of the patterned conductive layer is visually recognized. For the purpose of suppressing “,” a hard coat layer or a refractive index adjusting layer is provided as a functional layer. And a conductive layer is laminated | stacked on the functional layer of this base film, and the transparent conductive film for touchscreens is manufactured.

  As a functional thin film which comprises a base film, the hard-coat layer and the refractive index adjustment layer may be comprised by the single layer, and may be comprised by the multiple layer. As described above, examples of the refractive index adjustment layer include a high refractive index layer and / or a low refractive index layer.

  As a multi-layer configuration, a stacked configuration of a hard coat layer and a high refractive index layer, a stacked configuration of a hard coat layer and a low refractive index layer, a stacked configuration of a hard coat layer, a high refractive index layer, and a low refractive index layer And a laminated structure of a high refractive index layer and a low refractive index layer.

  Further, the hard coat layer may be a high refractive index hard coat layer having a function as a high refractive index layer of the refractive index adjusting layer. As a laminated structure in this case, a laminated structure of a high refractive index hard coat layer and a low refractive index layer can be mentioned.

  The hard coat layer and the high refractive index hard coat layer preferably have a pencil hardness of H or higher, more preferably 2H or higher. The upper limit is about 9H. The pencil hardness is measured according to JIS K5600-5-4 (1999). The hard coat layer and the high refractive index hard coat layer can have a pencil hardness of H or higher by using the above-mentioned active energy ray-curable resin.

  The thickness of the hard coat layer and the high refractive index hard coat layer is preferably in the range of 0.5 to 5 μm, and more preferably in the range of 0.8 to 3 μm.

  The refractive index of the hard coat layer is usually about 1.46 to 1.54, and this refractive index range can be obtained by using the aforementioned active energy ray-curable resin.

  The refractive index of the high refractive index hard coat layer is preferably in the range of 1.60 to 1.80, preferably in the range of 1.62 to 1.75, from the viewpoint of suppressing the color adjustment of the conductive layer and “bone appearance”. Is more preferable, and the range of 1.63 to 1.73 is particularly preferable. The high refractive index hard coat layer can be formed by containing the above-mentioned active energy ray-curable resin and the above-described metal oxide particles having a refractive index of 1.65 or more. The refractive index can be increased by increasing the content ratio of the metal oxide particles.

  The thickness of the high refractive index layer constituting the refractive index adjustment layer is preferably in the range of 20 to 200 nm, more preferably in the range of 30 to 100 nm, from the viewpoint of suppressing color adjustment of the conductive layer and “visibility”. A range of 30 to 60 nm is particularly preferable.

  The refractive index of the high refractive index layer is preferably in the range of 1.60 to 1.80, more preferably in the range of 1.62 to 1.75, from the viewpoint of suppressing color adjustment and “bone appearance” of the conductive layer. The range of 1.63 to 1.73 is particularly preferable. The high refractive index layer can be formed by containing the above-mentioned active energy ray-curable resin and the above-described metal oxide particles having a refractive index of 1.65 or more. The refractive index can be increased by increasing the content ratio of the metal oxide particles.

  The thickness of the low refractive index layer constituting the refractive index adjustment layer is preferably in the range of 10 to 70 nm and more preferably in the range of 15 to 60 nm from the viewpoint of suppressing the color adjustment of the conductive layer and suppressing “bone appearance”. A range of 15 to 50 nm is particularly preferable.

  The refractive index of the low refractive index layer is preferably 1.53 or less, more preferably 1.51 or less, and particularly preferably 1.50 or less, from the viewpoint of suppressing the color adjustment of the conductive layer and suppressing “bone appearance”. The lower limit refractive index of the low refractive index layer is preferably 1.35 or more, more preferably 1.38 or more, and particularly preferably 1.40 or more, from the viewpoint of suppressing color adjustment of the conductive layer and “bone appearance”. preferable.

  A low refractive index layer can adjust a refractive index to 1.53 or less by using the above-mentioned active energy ray curable resin and a low refractive index material. As the low refractive index material, low refractive index particles such as silica particles and magnesium fluoride particles, or fluorine compounds can be used.

The low refractive index layer may be a SiO ₂ film (film formation by sputtering).

  Examples of the functional layer according to the present invention include an antireflection layer, an antistatic layer, and an antifouling layer, as described above, in addition to the above-described conductive layer, hard coat layer, and refractive index adjusting layer.

  The antireflection layer preferably has a minimum reflectance of 2.0% or less on its surface, more preferably 1.5% or less, and more preferably 1.0% or less. The minimum reflectance of the lower limit is not particularly limited, but 0% is a practical lower limit.

The antistatic layer has a surface resistance value of preferably 10 ¹³ Ω / □ or less, more preferably 10 ¹² Ω / □ or less, and particularly preferably 10 ¹¹ Ω / □ or less. The lower limit is preferably 10 ⁶ Ω / □ or more from the viewpoint of distinguishing from the conductive layer.

  It is preferable that the antifouling layer does not adhere to the fingerprint of the finger or can be easily wiped off with a tissue paper or the like even if the fingerprint is attached.

  The surface roughness Ra of the functional layer surface of the transparent laminated film according to the present invention is preferably as small as possible from the viewpoint of increasing the transmittance of the transparent laminated film. Specifically, the surface roughness Ra of the functional layer surface is preferably 12 nm or less, more preferably 10 nm or less, and particularly preferably 8 nm or less. The lower limit is not particularly limited, but 0 nm is a substantial lower limit.

  As described above, when the surface roughness Ra of the surface of the functional layer of the transparent laminated film is reduced, the antiblocking property of the transparent laminated film may be reduced, but by providing the back coat layer of the present invention, blocking prevention is achieved. Can be improved.

[Method for producing transparent laminated film]
The transparent laminated film according to the present invention is preferably produced by the following production method. That is, the preferable manufacturing method of the transparent laminated film of this invention has a functional layer in one side (A surface) of a base film, and has a backcoat layer in the other side (B surface) of a base film. It is a manufacturing method of a transparent laminated film, Comprising: The process of laminating | stacking a functional layer on one side (A surface) of a base film, and the process of laminating | stacking a backcoat layer on the other side (B surface) of a base film In the step of laminating the back coat layer, at least a coating liquid containing a binder component, a silica particle treated with a fluorine compound, and a solvent is applied once on the base film to form one coating layer. The coating layer is separated, and an upper layer containing silica particles treated with a fluorine compound is formed on the opposite side of the base film, and components other than silica particles are the main components on the base film side. Wherein the allowed to form a lower layer which is a method for producing a transparent laminate film.

  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) Presence / absence of interface between upper layer and lower layer constituting back coat layer By observing a cross section of the back coat layer using a transmission electron microscope (H-7100FA type manufactured by Hitachi), The presence / absence of an interface between the upper layer and the lower layer to be formed was determined. The presence or absence of the interface was determined according to the following method.

  An image taken with a transmission electron microscope at a magnification of 200,000 times was affixed to presentation software (Microsoft Power Point 2003) using a scanner. Next, image control processing (contrast was set to 90%) of the attached photograph was performed to enhance the contrast. At this time, a case where a clear boundary can be drawn at the interface between one layer and the other layer was regarded as a clear interface (in Table 1, a case where a clear boundary can be drawn). The case where there is an interface is indicated by “◯”, and the case where a clear boundary cannot be drawn is indicated by “×” as no interface.)

(2) Thickness of upper layer and lower layer constituting backcoat layer Lower part constituting backcoat layer by observing cross section of backcoat layer using transmission electron microscope (Hitachi H-7100FA type) The thickness of the side layer and the upper layer was measured. The thickness of each layer was measured according to the following method. The thickness of each layer was read by software (image processing software EasyAccess) from an image obtained by photographing an ultrathin section of the cross section of the backcoat layer with a transmission electron microscope at a magnification of 200,000 times. The layer thickness of 30 points in total was measured and taken as the average value.

(3) Area ratio of silica particles in the upper layer constituting the backcoat layer From an image obtained by photographing an ultrathin section of the cross section of the backcoat layer with a transmission electron microscope (H-7100FA type manufactured by Hitachi) at a magnification of 200,000 times The ratio of the cross-sectional area of the silica particles to the cross-sectional area of the upper layer was determined.

(4) Area ratio of silica particles in the lower layer constituting the backcoat layer Image obtained by photographing an ultrathin section of the cross section of the backcoat layer with a transmission electron microscope (H-7100FA type manufactured by Hitachi) at a magnification of 200,000 times From this, the ratio of the cross-sectional area of the silica particles to the cross-sectional area of the lower layer was determined.

(5) Thickness of easy-adhesion layer, high refractive index layer, low refractive index layer, and hard coat layer The cross section of the transparent laminated film was cut into ultrathin sections and 50,000 with a transmission electron microscope (Hitachi H-7100FA type). The cross section of the sample was observed at a magnification of 300 to 300,000 times, and the thickness of each layer was measured. In addition, when the boundary of each layer was not clear, the dyeing | staining process was performed as needed.

(6) Refractive index measurement 1 (refractive index of easy adhesion layer and functional layer)
About the coating film (dry thickness of about 2 μm) formed by coating each of the easy-adhesion layer and the functional layer (hard coat layer, high refractive index layer, low refractive index layer) on a silicon wafer with a spin coater. The refractive index of 589 nm was measured with a phase difference measuring device (Nikon Corporation: NPDM-1000) under a temperature condition of 25 ° C.

(7) Refractive index measurement 2
The refractive index of the base film (PET film) was measured at 589 nm with an Abbe refractometer according to JIS K7105 (1981).

(8) Measurement of total light transmittance of transparent laminated film Based on JIS-K7361 (1997), it measured using turbidimeter NDH2000 (made by Nippon Denshoku Industries Co., Ltd.).

(9) Measurement of the minimum reflectance of the back coat layer surface Measurement with a black adhesive tape (Nitto Denko “Vinyl Tape No. 21 Tokuhaba Black”) attached to the A side (the functional layer side surface) of the transparent laminated film A sample is prepared, and using this measurement sample, the reflection spectrum in the wavelength region of 400 to 800 nm on the B surface (the surface on the backcoat layer side) is measured with a spectrophotometer UV-3100 manufactured by Shimadzu Corporation. Bottom reflectance).

(10) Measurement of surface roughness Ra The surface roughness Ra of the functional layer surface and the backcoat layer surface of the transparent laminated film was measured using a surface roughness meter (SURFCORDER ET4000A: manufactured by Kosaka Laboratory Ltd.), JIS- Based on B-0601 (2001), the measurement was performed under the following measurement conditions. The surface roughness Ra is a contour curve (roughness curve) obtained by blocking a long wavelength component with a high-pass filter having a cutoff value λc from a measured cross-sectional curve, and is obtained at the reference length of the curve. It is the average of the absolute values of the height (distance from the average line to the measurement curve).
<Measurement conditions>
Measurement speed: 0.1 mm / S
Evaluation length: 10mm
Cut-off value λc: 0.1 mm
Filter: Low-frequency cut of the Gauntian filter.

(11) Evaluation of anti-blocking property The transparent laminated film is cut to produce two sheet pieces (20 cm × 15 cm). The two sheets are overlaid so that the A side (the functional layer side surface) and the B side (the back coat layer side surface) face each other. Next, a sample in which two sheet pieces are overlapped is sandwiched between glass plates, a weight of about 2 kg is placed, and left in an atmosphere of 50 ° C. and 80% (RH) for 48 hours. Next, the overlapping surface was visually observed to confirm the occurrence of Newton rings, and then both were peeled off and evaluated according to the following criteria.
○ (best): No Newton ring is generated before peeling, and light peeling occurs without peeling noise during peeling.
Δ (good): Some Newton rings are generated before peeling, and peeling is performed while making a small peeling sound.
X (defect): Newton rings are generated on the entire surface before peeling, and peeling occurs with a loud peeling sound during peeling.

(12) Evaluation of interference fringes on the back coat layer surface A black adhesive tape (Nitto Denko “Vinyl Tape No. 21 Tokuhaba Black”) was applied to the A side (the functional layer side surface) of the transparent laminated film, and the B side ( The backcoat layer side surface) was visually observed under a darkroom three-wavelength fluorescent lamp and evaluated according to the following criteria.
○ (Good): Interference fringes are hardly observed.
X (defect): Interference fringes are observed.

[material]
<Easily adhesive layer>
The following two types of coating solutions were prepared as the coating solution for forming the easy adhesion layer.

<Easily adhesive layer forming coating solution a1>
100 parts by mass of the following naphthalene ring-containing polyester resin, 15 parts by mass of a melamine-based crosslinking agent (methylol-type melamine-based crosslinking agent (“Nicarac MW12LF” manufactured by Sanwa Chemical Co., Ltd.)), and an average particle diameter of 190 nm It is an aqueous dispersion containing 1 part by mass of colloidal silica. The refractive index of this coating solution was 1.58.

<Naphthalene ring-containing polyester resin>
A polyester resin having the following copolymer composition.
・ Carboxylic acid component terephthalic acid 35mol%
2,6-Naphthalenedicarboxylic acid 9 mol%
5-Na sulfoisophthalic acid 6 mol%
・ Glycol component ethylene glycol 49 mol%
Diethylene glycol 1 mol%.

<Easily adhesive layer forming coating solution a2>
100 parts by mass of the naphthalene ring-containing polyester resin, 60 parts by mass of zirconium oxide, and 15 parts by mass of a melamine-based cross-linking agent (methylol-type melamine-based cross-linking agent (“Nicarac MW12LF” manufactured by Sanwa Chemical Co., Ltd.)) An aqueous dispersion containing 1 part by mass of colloidal silica having an average particle diameter of 190 nm. The refractive index of this coating solution was 1.65.

<Functional layer>
As the functional layer, the following coating liquid for forming a hard coat layer, coating liquid for forming a high refractive index layer, and coating liquid for forming a low refractive index layer were prepared.

<Coating liquid for forming hard coat layer>
As active energy ray-curable resin, 58 parts by mass of dipentaerythritol hexaacrylate, and urethane acrylate oligomer (“UN-901T” of Negami Kogyo Co., Ltd .; containing 9 polymerizable functional groups in the molecule), 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). The refractive index of this coating solution was 1.52.

<Coating liquid for forming a high refractive index layer>
41 parts by mass of dipentaerythritol hexaacrylate as an active energy ray-curable resin, 56 parts by mass of zirconium oxide as metal oxide fine particles, and a photopolymerization initiator (“Irgacure 184” manufactured by Ciba Specialty Chemicals) It was prepared by dispersing or dissolving 3 parts by mass in an organic solvent (methyl isobutyl ketone). The refractive index of this coating solution was 1.68.

<Coating liquid for forming a low refractive index layer>
65 parts by mass of dipentaerythritol hexaacrylate as active energy ray-curable resin, 30 parts by mass of fluorine-containing compound (fluorine resin “AR110” manufactured by Daikin Industries, Ltd.), colloidal silica (organo of Nissan Chemical Industries, Ltd.) 2 parts by mass of silica sol “MIBK-SD-L” (average particle size 45 nm) in terms of solid content, oligomer type photopolymerization initiator (Ezacure One manufactured by Lamberti Co., Ltd .; poly [2-hydroxy-2-methyl] −1- [4- (1-methylvinyl) phenyl] propanone]) 3 parts by mass is dispersed and dissolved in an organic solvent (a mixed solvent of methyl isobutyl ketone and propylene glycol monoethyl ether in a mass ratio of 1: 1). Prepared. The refractive index of this coating solution was 1.47.

<Backcoat layer forming coating solution>
The following six types of coating solutions were prepared as the back coating layer forming coating solutions.

<Backcoat layer forming coating solution bc1>
38 parts by mass of a silica particle dispersion (a) treated with the following fluorine compound, 11 parts by mass of dipentaerythritol hexaacrylate as an active energy ray-curable resin, a photopolymerization initiator (Ciba Specialty Chemicals Co., Ltd.) "Irgacure 184") manufactured by 0.6 parts by weight, methyl isobutyl ketone 31 parts by weight, ethylene glycol monobutyl ether 10 parts by weight, and fluorine compound B ("R1820" manufactured by Daikin Corporation) 3 parts by weight contains.

[Silica particle dispersion treated with fluorine compound (a)]
To 15 parts by mass of isopropyl alcohol dispersion of hollow silica particles (manufactured by JGC Catalysts & Chemicals Co., Ltd .: solid content concentration 20% by mass, average particle size 50 nm), (CH ₂ = C (CH ₃ ) COOC ₃ H ₆ Si (OCH ₃ ) ₃ ) 1.37 parts by mass, 0.17 parts by mass of a 10% by mass aqueous formic acid solution, and 0.306 parts by mass of water were mixed and stirred at 70 ° C. for 1 hour. Next, 1.38 parts by mass of H ₂ C═CHCOOCH ₂ (CF ₂ ) ₈ F and 0.057 parts by mass of 2,2-azobisisobutyronitrile were added as fluorine compounds, and then heated at 90 ° C. for 60 minutes. Stir. Subsequently, isopropyl alcohol was added and diluted to prepare a silica particle dispersion (a) having a solid content concentration of 3.5% by mass.

<Backcoat layer forming coating solution bc2>
43 parts by mass of the silica particle dispersion (a) treated with the above fluorine compound, 36 parts by mass of isopropyl alcohol dispersion of zirconium oxide (manufactured by CIK Nanotech Co., Ltd .; solid content concentration 30% by mass; average particle size 19 nm) 5 parts by mass of dipentaerythritol hexaacrylate as an active energy ray-curable resin, 0.3 parts by mass of a photopolymerization initiator (“Irgacure 184” manufactured by Ciba Specialty Chemicals), ethylene glycol monobutyl ether 10 parts by mass, 6 parts by mass of 2-propanol, and 3 parts by mass of fluorine compound B (“R1820” manufactured by Daikin Co., Ltd.).

<Backcoat layer forming coating solution bc3>
38 parts by mass of silica particle dispersion (b) treated with the following fluorine compound, 11 parts by mass of dipentaerythritol hexaacrylate as an active energy ray-curable resin, photopolymerization initiator (Ciba Specialty Chemicals Co., Ltd.) "Irgacure 184") manufactured by 0.6 parts by weight, methyl isobutyl ketone 31 parts by weight, ethylene glycol monobutyl ether 10 parts by weight, and fluorine compound B ("R1820" manufactured by Daikin Corporation) 3 parts by weight contains.

[Silica particle dispersion treated with fluorine compound (b)]
To 15 parts by mass of colloidal silica (manufactured by Fuso Chemical Industry Co., Ltd .: solid content concentration 30% by mass, average particle size 18 nm), 1.37 parts by mass of methacryloxypropyltrimethoxysilane and 10% by mass formic acid aqueous solution 0 .17 parts by mass were mixed and stirred at 70 ° C. for 1 hour. Next, after adding 1.38 parts by mass of H ₂ C═CH—COO—CH ₂ — (CF ₂ ) ₈ F and 0.057 parts by mass of 2,2-azobisisobutyronitrile as a fluorine compound, The mixture was heated and stirred at 90 ° C. for 60 minutes. Then, isopropyl alcohol was added and diluted to prepare a silica particle dispersion (b) having a solid content concentration of 3.5% by mass.

<Backcoat layer forming coating solution bc4>
43 parts by mass of silica particle dispersion (b) treated with the above-mentioned fluorine compound, 36 parts by mass of isopropyl alcohol dispersion of zirconium oxide (manufactured by CIK Nanotech Co., Ltd .; solid content concentration 30% by mass; average particle size 19 nm) 5 parts by mass of dipentaerythritol hexaacrylate as an active energy ray-curable resin, 0.3 parts by mass of a photopolymerization initiator (“Irgacure 184” manufactured by Ciba Specialty Chemicals), ethylene glycol monobutyl ether 10 parts by mass, 6 parts by mass of 2-propanol, and 3 parts by mass of fluorine compound B (“R1820” manufactured by Daikin Co., Ltd.).

<Backcoat layer forming coating solution bc5>
5 parts by mass of colloidal silica (manufactured by Fuso Chemical Industry Co., Ltd .: solid content concentration 30% by mass, average particle size 18 nm), 11 parts by mass of dipentaerythritol hexaacrylate as an active energy ray curable resin, light It contains 0.6 parts by mass of a polymerization initiator (“Irgacure 184” manufactured by Ciba Specialty Chemicals Co., Ltd.), 31 parts by mass of methyl isobutyl ketone, and 10 parts by mass of ethylene glycol monobutyl ether.

<Backcoat layer forming coating solution bc6>
92 parts by mass of dipentaerythritol hexaacrylate as an active energy ray curable resin, solid styrene-acrylic copolymer resin particles (trade name “STAPHYLOID EA-1135” manufactured by Ganz Kasei Co., Ltd .; average particle size 130 nm) 8 parts by mass, 5 parts by mass of a photopolymerization initiator (“Irgacure (registered trademark) 184” manufactured by Ciba Specialty Chemicals Co., Ltd.) in an organic solvent (ethyl acetate: toluene = 1: 1 (mass ratio)) A coating solution (solid content concentration of 30% by mass) dissolved or dispersed in (mixed solvent) was prepared.

<Backcoat layer forming coating solution bc7>
Isopropyl alcohol dispersion of hollow silica particles (manufactured by JGC Catalysts & Chemicals Co., Ltd .: solid content concentration 20% by mass, average particle size 50 nm) 7.5 parts by mass, 11 masses of dipentaerythritol hexaacrylate as an active energy ray curable resin Part, 0.6 parts by mass of photopolymerization initiator (“Irgacure 184” manufactured by Ciba Specialty Chemicals Co., Ltd.), 31 parts by mass of methyl isobutyl ketone, 10 parts by mass of ethylene glycol monobutyl ether, and fluorine compound B (3 parts by mass of “R1820” manufactured by Daikin Corporation).

[Example 1]
A transparent laminated film (a base film of a transparent conductive film for a touch panel) was produced in the following manner.

<Preparation of easy-adhesion layer laminated polyethylene terephthalate film (PET film)>
PET pellets (intrinsic viscosity 0.63 dl / g) substantially free of externally added particles are sufficiently vacuum-dried, then supplied to an extruder, melted at 285 ° C., extruded from a T-shaped die into a sheet shape, It was wound around a mirror-casting drum having a surface temperature of 25 ° C. using an electric application casting method and cooled and solidified. This unstretched film was heated to 90 ° C. and stretched 3.4 times in the longitudinal direction to obtain a uniaxially stretched film. After performing corona discharge treatment in air on both surfaces of the uniaxially stretched film, the easy-adhesion layer-forming coating solution a1 was applied to both surfaces of the uniaxially stretched film.

  Next, the uniaxially stretched film coated with the coating liquid for forming each easy-adhesion layer on both sides is held with a clip, guided to a preheating zone, dried at an ambient temperature of 75 ° C., raised to 110 ° C. using a radiation heater, and again After drying at 90 ° C., the film is continuously stretched 3.5 times in the width direction in a heating zone at 120 ° C., followed by heat treatment for 20 seconds in the heating zone at 220 ° C. A film was prepared.

  The thickness of the easy adhesion layer laminated PET film thus obtained was 100 μm, and the thickness of the easy adhesion layer laminated on both surfaces was 90 nm. Moreover, the refractive index of the PET film was 1.65, and the refractive index of the easy adhesion layer laminated on both surfaces was 1.58.

  In addition, the refractive index of PET film measured the refractive index of the PET film manufactured on the conditions similar to the above except not laminating | stacking an easily bonding layer on both surfaces, and made the value the refractive index of PET film.

<Lamination of back coat layer>
The above-mentioned coating liquid for forming a back coat layer bc1 is applied on the easy-adhesion layer on one surface (B surface) of the easy-adhesion layer-laminated PET film obtained above by a gravure coating method so that the dry thickness becomes 900 nm. Then, after drying at two stages of 45 ° C. and 85 ° C., it was cured by irradiation with ultraviolet rays to form a backcoat layer.

  It was confirmed that this back coat layer was separated into an upper layer and a lower layer with a clear interface. The thickness of the upper layer was 100 nm, and the thickness of the lower layer was 800 nm.

  The upper layer contained silica particles (hollow silica particles), and the area ratio of the silica particles in the upper layer was 75%. The lower layer was a layer mainly composed of a binder component (active energy ray-curable resin), and the area ratio of silica particles in the lower layer was 5% or less. The minimum reflectance of the upper layer surface was 0.8%.

<Lamination of functional layer>
On the easy-adhesion layer on the other surface (A surface) of the easy-adhesion layer-laminated PET film on which the backcoat layer is laminated as described above, the following hard coat layer, refractive index adjustment layer (high refractive index layer and A low refractive index layer) was laminated in this order.

<Lamination of hard coat layer>
The above-mentioned coating liquid for forming a hard coat layer was applied by a gravure coating method, dried at 90 ° C., and then cured by irradiation with ultraviolet rays to form a hard coat layer. This hard coat layer had a thickness of 1.0 μm and a refractive index of 1.52.

<Lamination of high refractive index layer>
On the hard coat layer formed above, the above-described coating solution for forming a high refractive index layer was applied by a gravure coating method, dried at 70 ° C., and then irradiated with ultraviolet rays to be cured to form a high refractive index layer. This high refractive index layer had a refractive index of 1.68 and a thickness of 35 nm.

<Lamination of low refractive index layer>
On the high refractive index layer formed above, it was applied by a low refractive index layer forming coating liquid gravure coating method, dried at 70 ° C., and irradiated with ultraviolet rays to be cured to form a low refractive index layer. The low refractive index layer had a refractive index of 1.47 and a thickness of 40 nm.

[Example 2]
A transparent laminated film (a base film of a transparent conductive film for a touch panel) was produced in the following manner.

<Preparation of easy-adhesion layer laminated polyethylene terephthalate film (PET film)>
PET pellets (intrinsic viscosity 0.63 dl / g) substantially free of externally added particles are sufficiently vacuum-dried, then supplied to an extruder, melted at 285 ° C., extruded from a T-shaped die into a sheet shape, It was wound around a mirror-casting drum having a surface temperature of 25 ° C. using an electric application casting method and cooled and solidified. This unstretched film was heated to 90 ° C. and stretched 3.4 times in the longitudinal direction to obtain a uniaxially stretched film. After performing corona discharge treatment in air on both surfaces of the uniaxially stretched film, an easy-adhesion layer-forming coating solution a2 was applied to both surfaces of the uniaxially stretched film.

  Next, the uniaxially stretched film coated with the coating liquid for forming each easy-adhesion layer on both sides is held with a clip, guided to a preheating zone, dried at an ambient temperature of 75 ° C., raised to 110 ° C. using a radiation heater, and again After drying at 90 ° C., the film is continuously stretched 3.5 times in the width direction in a heating zone at 120 ° C., followed by heat treatment for 20 seconds in the heating zone at 220 ° C. A film was prepared.

  The thickness of the easy adhesion layer laminated PET film thus obtained was 100 μm, and the thickness of the easy adhesion layer laminated on both surfaces was 20 nm. Moreover, the refractive index of PET film was 1.65, and the refractive index of the easily bonding layer laminated | stacked on both surfaces was 1.65, respectively.

  In addition, the refractive index of PET film measured the refractive index of the PET film manufactured on the conditions similar to the above except not laminating | stacking an easily bonding layer on both surfaces, and made the value the refractive index of PET film.

<Lamination of back coat layer>
The above-mentioned coating liquid for forming a back coat layer bc2 is applied by a gravure coating method on the easy adhesion layer on one surface (B surface) of the easy adhesion layer laminated PET film obtained above so that the dry thickness becomes 800 nm. Then, after drying at two stages of 45 ° C. and 85 ° C., it was cured by irradiation with ultraviolet rays to form a backcoat layer.

  It was confirmed that this back coat layer was separated into an upper layer and a lower layer with a clear interface. The upper layer had a thickness of 100 nm and the lower layer had a thickness of 700 nm.

  The upper layer contained silica particles (hollow silica particles), and the area ratio of the silica particles in the upper layer was 75%. The lower layer was a layer mainly composed of a binder component (active energy ray-curable resin) and metal oxide particles (zirconium oxide), and the area ratio of silica particles in the lower layer was 5% or less. The minimum reflectance of the upper layer surface was 0.3%.

<Lamination of functional layer>
The following refractive index adjusting layer (high refractive index hard coat layer and low refractive index) as a functional layer on the easy adhesion layer on the other surface (A surface) of the easy adhesion layer laminated PET film on which the backcoat layer is laminated as described above Rate layer).

<Lamination of high refractive index hard coat layer>
The above-described coating solution for forming a high refractive index layer was applied by a gravure coating method so as to have a dry thickness of 1.0 μm, dried at 90 ° C., and then cured by irradiation with ultraviolet rays to form a high refractive index hard coat layer. . The high refractive index hard coat layer had a refractive index of 1.68 and a thickness of 1.0 μm.

<Lamination of low refractive index layer>
On the high refractive index hard coat layer formed above, the low refractive index layer forming coating solution is applied by the gravure coating method, dried at 70 ° C., and irradiated with ultraviolet rays to be cured to form the low refractive index layer. did. The low refractive index layer had a refractive index of 1.47 and a thickness of 35 nm.

[Example 3]
In Example 1, a transparent laminated film (a base film of a transparent conductive film for a touch panel) was produced in the same manner as in Example 1 except that the backcoat layer-forming coating solution was changed to bc3.

  It was confirmed that this back coat layer was separated into an upper layer and a lower layer with a clear interface. The thickness of the upper layer was 100 nm, and the thickness of the lower layer was 800 nm.

  The upper layer contained silica particles (colloidal silica), and the area ratio of the silica particles in the upper layer was 60%. The lower layer was a layer mainly composed of a binder component (active energy ray-curable resin), and the area ratio of silica particles in the lower layer was 5% or less. The minimum reflectance of the upper layer surface was 2.7%.

[Example 4]
In Example 2, a transparent laminated film (a base film of a transparent conductive film for a touch panel) was produced in the same manner as in Example 2 except that the coating liquid for forming the backcoat layer was changed to bc4.

  It was confirmed that this back coat layer was separated into an upper layer and a lower layer with a clear interface. The upper layer had a thickness of 100 nm and the lower layer had a thickness of 700 nm.

  The upper layer contained silica particles (colloidal silica), and the area ratio of the silica particles in the upper layer was 60%. The lower layer was a layer mainly composed of a binder component (active energy ray-curable resin) and metal oxide particles (zirconium oxide), and the area ratio of silica particles in the lower layer was 5% or less. The minimum reflectance of the upper layer surface was 1.8%.

[Comparative Example 1]
In Example 1, the transparent laminated film (transparent conductive film for touch panel) was changed in the same manner as in Example 1 except that the backcoat layer-forming coating solution was changed to bc5 and the dry thickness of the backcoat layer was changed to 900 nm. Base film).

  It was confirmed that this back coat layer was not separated into an upper layer and a lower layer. The thickness of the back coat layer was 900 nm, and the minimum reflectance of the surface of the back coat layer was 3.5%.

[Comparative Example 2]
In Example 1, except that the backcoat layer-forming coating solution was changed to bc6 and the dry thickness of the backcoat layer was changed to 900 nm, the transparent laminated film (transparent conductive film for touch panel) was changed in the same manner as in Example 1. Base film).

  It was confirmed that this back coat layer was not separated into an upper layer and a lower layer. The thickness of the back coat layer was 900 nm, and the minimum reflectance of the back coat layer surface was 3.6%.

[Comparative Example 3]
In Example 1, the transparent laminated film (transparent conductive film for touch panel) was changed in the same manner as in Example 1 except that the backcoat layer-forming coating solution was changed to bc7 and the dry thickness of the backcoat layer was changed to 900 nm. Base film).

  It was confirmed that this back coat layer was not separated into an upper layer and a lower layer. The thickness of the back coat layer was 900 nm, and the minimum reflectance of the back coat layer surface was 3.1%.

[Comparative Example 4]
In the same manner as in Example 1, an easy-adhesion layer-laminated PET film was prepared, and the following backcoat hardcoat layer and backcoat low-refractive index layer were sequentially laminated as a backcoat layer on the B-side easy-adhesion layer. Produced a transparent laminated film (a base film of a transparent conductive film for a touch panel) in the same manner as in Example 1. The minimum reflectance of the back coat layer surface was 0.8%.

  This back coat layer is obtained by applying two layers roughly corresponding to the upper layer and the lower layer of the back coat layer of Example 1 and laminating (coating) them separately. The back coat low refractive index layer of this back coat layer roughly corresponds to the upper layer of Example 1, and the back coat hard coat layer roughly corresponds to the lower layer of Example 1.

<Lamination of hard coat layer for back coat>
The following coating liquid for forming a backcoat hard coat layer was applied by a gravure coating method, dried at 90 ° C., and then cured by irradiation with ultraviolet rays to form a backcoat hardcoat layer. The back coat hard coat layer had a refractive index of 1.51 and a thickness of 800 nm.

<Backcoat hard coat layer forming coating solution>
94 parts by mass of dipentaerythritol hexaacrylate as an active energy ray curable resin and 6 parts by mass of a photopolymerization initiator (“Irgacure (registered trademark) 184” manufactured by Ciba Specialty Chemicals) are used as an organic solvent (methyl isobutyl ketone). It was prepared by dispersing and dissolving.

<Lamination of low refractive index layer for back coat>
The following coating liquid for forming a low refractive index layer for back coating is applied by the gravure coating method on the hard coating layer for back coating formed above, dried at 80 ° C., cured by irradiation with ultraviolet rays, and back coating. A low refractive index layer was formed. The back coating low refractive index layer had a refractive index of 1.35 and a thickness of 100 nm. Further, the area ratio of the silica particles in the low refractive index layer for the back coat was 75%.

<Liquid for forming low refractive index layer for back coat>
As active energy ray-curable resin, 47 parts by mass of dipentaerythritol hexaacrylate, isopropyl alcohol dispersion of hollow silica particles (hollow silica manufactured by JGC Catalysts & Chemicals Co., Ltd .: solid content concentration 20% by mass, average particle size 50 nm) are solid. It was prepared by dispersing and dissolving 50 parts by mass in terms of minutes and 3 parts by mass of a photopolymerization initiator (“Irgacure (registered trademark) 184” manufactured by Ciba Specialty Chemicals Co., Ltd.) in an organic solvent (methyl isobutyl ketone).

<Evaluation>
About each transparent laminated film produced above, total light transmittance, blocking prevention property, the presence or absence of the interface of an upper layer and a lower layer, the minimum reflectance, an interference fringe, and surface roughness Ra were evaluated. The results are shown in Table 1.

Claims (8)

  A transparent laminated film having a functional layer on one side (A side) of a base film and a back coat layer on the other side (B side) of the base film, wherein the back coat layer is one The coating layer is formed by separating the upper layer and the lower layer into two layers, and an upper layer containing silica particles is formed on the opposite side of the base film, Transparent laminated film.   The transparent laminated film according to claim 1, wherein the coating layer contains at least a binder component and silica particles.   The transparent laminated film according to claim 1 or 2, wherein the coating layer contains at least a binder component, silica particles, and metal oxide particles.   The transparent laminated film according to any one of claims 1 to 3, wherein the silica particles are treated with a fluorine compound.   The transparent laminated film in any one of Claims 1-4 whose said silica particle is a hollow silica particle.   The transparent laminated film in any one of Claims 1-5 whose minimum reflectance of the said upper layer surface is 2.0% or less. It is a method for producing a transparent laminated film having a functional layer on one side (A side) of a base film and having a back coat layer on the other side (B side) of the base film,
Having a step of laminating a functional layer on one side (A side) of the base film, and a step of laminating a backcoat layer on the other side (B side) of the base film,
In the step of laminating the back coat layer, at least a coating solution containing silica particles treated with a binder component, a fluorine compound, and a solvent is applied once onto a base film to form one coating layer. The coating layer is separated into layers, an upper layer containing silica particles treated with a fluorine compound is formed on the opposite side of the base film, and a lower layer mainly composed of components other than silica particles is formed on the base film side. A process for producing a transparent laminated film, characterized in that   The method for producing a transparent laminated film according to claim 7, wherein the coating solution further contains metal oxide particles.