JP2015122061A - Hard coat film for touch panel, and touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard coat film for a touch panel, which has excellent slippery property and can decrease a resistance value of a conductive layer.SOLUTION: The hard coat film for a touch panel includes an optical functional layer laminated on a light-transmitting substrate. The optical functional layer has a rugged pattern on a surface thereof, in which both a ten-point average roughness and an arithmetic average roughness of the rugged pattern of the optical functional layer, measured by use of a scanning white-light interference microscope in a 0.12 mm square measurement field of view, are larger than a ten-point average roughness and an arithmetic average roughness of the rugged pattern of the optical functional layer, measured by use of a scanning probe microscope in a 5 μm square measurement field of view.

Description

The present invention relates to a hard coat film for a touch panel and a touch panel.

Conventionally, a transparent conductive laminate in which a conductive film is formed on a light-transmitting substrate is a flat panel display such as a liquid crystal display device or an electroluminescence (EL) display, a transparent electrode of a touch panel, or the like. Widely used in field applications. In particular, in recent years, the demand for transparent conductive laminates has increased due to the spread of portable information terminals equipped with touch panels and notebook computers with touch panels.

As a transparent conductive laminate used for a touch panel, a structure in which a conductive film made of a conductive metal oxide such as ITO is formed on a light transmissive substrate made of a polymer material is known. From the viewpoint of preventing deterioration of transparency due to precipitation of low molecular weight components such as oligomers from the light transmissive substrate, curing is performed on the light transmissive substrate supporting the conductive layer for the purpose of preventing diffusion of the low molecular weight components. It is known to form a resin layer (undercoat layer) (see, for example, Patent Document 1 and Patent Document 2).

In addition, as a transparent conductive laminate used for a conventional touch panel, a structure in which a high refractive index layer and a low refractive index layer are laminated between a light-transmitting substrate and a conductive film to make the conductive film invisible Is also known (see, for example, Patent Document 3).
However, the transparent conductive laminate used in such a conventional touch panel has a problem that the slipperiness of the conductive film on the surface is inadequate, and the resistance value of the conductive film is increased due to inferior blocking resistance. There was a problem.

JP 2002-103504 A JP 2012-206275 A Patent No. 4661995

In view of the above situation, the present invention provides a hard coat film for a touch panel that is excellent in slipperiness and can reduce the resistance of the conductive layer when the conductive layer is formed, and the touch panel hardware. An object of the present invention is to provide a touch panel using a coat film.

The present invention is a hard coat film for a touch panel in which an optical functional layer is laminated on a light-transmitting substrate, and the optical functional layer has a concavo-convex shape on the surface, and a scanning white interference microscope is used. Using the scanning probe microscope, the ten-point average roughness and the arithmetic average roughness of the concavo-convex shape of the optical functional layer measured as a measurement visual field of 0.12 mm □ were measured as a measurement visual field of 5 μm □. A hard coat film for a touch panel, which is larger than the ten-point average roughness and the arithmetic average roughness of the irregular shape of the optical functional layer.

In the hard coat film for a touch panel of the present invention, the ten-point average roughness of the uneven shape of the upper optical functional layer measured with a scanning white interference microscope as a measurement visual field of 0.12 mm □ is 50 to 500 nm, and the optical function The arithmetic average roughness of the concavo-convex shape of the layer is preferably 0.5 to 10.0 nm, and the concavo-convex shape of the optical functional layer measured using a scanning probe microscope with a measurement field of view of 5 μm □. The ten-point average roughness is preferably 50 nm or less, and the arithmetic average roughness of the irregular shape of the optical functional layer is preferably 3.0 nm or less.
The optical functional layer preferably has at least an undercoat layer and a low refractive index layer, and the undercoat layer is preferably laminated on the light transmissive substrate.
The optical functional layer further has a high refractive index layer, and the undercoat layer, the high refractive index layer, and the low refractive index layer are preferably laminated in this order on the light transmissive substrate. .
The undercoat layer contains fine particles a, the high refractive index layer contains fine particles b, the low refractive index layer contains fine particles c, and the fine particles a have an average particle size of 0.1 to 0.1. The average particle diameter of 3.0 μm, the fine particles b is preferably 15 to 50 nm, and the average particle diameter of the fine particles c is preferably 5 nm or more and less than 30 nm.
The fine particles a contained in the undercoat layer are silica fine particles, the fine particles b contained in the high refractive index layer are zirconium oxide fine particles, and the fine particles c contained in the low refractive index layer are Silica fine particles are preferable.
The fine particles a contained in the undercoat layer are spherical silica fine particles or colloidal silica fine particles, and the fine particles b contained in the high refractive index layer are amorphous zirconium oxide fine particles, and the low refractive index layer The fine particles c contained in are preferably colloidal silica fine particles.
Moreover, it is preferable that a region where neither the fine particles b nor the fine particles c exist is formed at the interface between the high refractive index layer and the low refractive index layer.
In the hard coat film for a touch panel of the present invention, the refractive index of the undercoat layer is 1.45 to 1.60, the refractive index of the high refractive index layer is 1.55 to 1.75, and The refractive index of the low refractive index layer is 1.35 to 1.55, and each of the high refractive index layer, the undercoat layer, and the low refractive index layer satisfies the relationship of the following formula (2). It is preferable.
Refractive index of high refractive index layer> Refractive index of undercoat layer> Refractive index of low refractive index layer (2)
Moreover, it is preferable that the conductive layer is formed in the hard coat film for touchscreens of this invention on the opposite side to the high refractive index layer side of the said low refractive index layer.
In the hard coat film for a touch panel of the present invention, an inorganic layer is preferably formed between the low refractive index layer and the conductive layer.

The present invention is also a touch panel using the hard coat film for a touch panel of the present invention.
The present invention is described in detail below.

As a result of intensive studies on a hard coat film for a touch panel used in a touch panel in which an optical functional layer is laminated on one surface of a light-transmitting substrate, the present inventors have found that the surface of the optical functional layer has predetermined irregularities. By forming the shape, a hard coat film for a touch panel that is excellent in slipperiness and can reduce the resistance of the conductive layer when the conductive layer is formed on the optical functional layer is obtained. As a result, the present invention has been completed.

In the hard coat film for a touch panel of the present invention, an optical functional layer is laminated on a light-transmitting substrate.
In such a hard coat film for a touch panel of the present invention, the optical functional layer has a concavo-convex shape on the surface, and the measurement visual field is 0.12 mm □ (hereinafter referred to as a macro visual field) using a scanning white interference microscope. 10) The measured 10-point average roughness and arithmetic average roughness were measured using a scanning probe microscope as a measurement field of view of 5 μm □ (hereinafter also referred to as a micro field of view) It is larger than the arithmetic mean roughness value.
In the hard coat film for a touch panel of the present invention, the scanning white interference microscope specifically includes “Zygo New View 6300” and “Zygo New View 7300” manufactured by Zygo Corporation, and the like. Specific examples of the scanning probe microscope include SPM-9600 manufactured by Shimadzu Corporation.
The values of the ten-point average roughness and arithmetic average roughness measured in the macro field of view are parameters representing the state of large unevenness formed on the surface of the optical functional layer that affects the slipperiness, and the micro field of view. The ten-point average roughness and the arithmetic average roughness measured in (1) are parameters representing the state of a small uneven shape formed on the surface of the optical functional layer that contributes to lowering the resistance value of the conductive layer formed on the optical functional layer. In addition, since these parameters have the above relationship, the hard coat film for a touch panel of the present invention has excellent slipperiness, and the resistance value of the conductive layer to be formed can be improved.

In the hard coat film for a touch panel of the present invention, the ten-point average roughness in the macro visual field on the surface of the optical functional layer is preferably 50 to 500 nm, and the arithmetic average roughness is preferably 0.5 to 10.0 nm. If the 10-point average roughness in the macro field of view is less than 50 nm, the slipperiness may be insufficient and the blocking resistance may be deteriorated. If it exceeds 500 nm, a cloudiness (whitening) is observed and the transparency is high. May decrease. Further, if the arithmetic average roughness in the macro field of view is less than 0.5 nm, the slipperiness becomes insufficient and the blocking resistance may be deteriorated. If it exceeds 10.0 nm, the cloudiness (whitening) is observed. Transparency may be reduced. The more preferable lower limit of the ten-point average roughness in the macro field of view is 150 nm, and the more preferable upper limit is 400 nm. The more preferable lower limit of the arithmetic average roughness in the macro field of view is 1.0 nm, and the more preferable upper limit is 6.0 nm. .
The ten-point average roughness in the macro field of view is a value calculated by processing based on Rz defined in JIS B0601 (1994), and the arithmetic average roughness in the macro field of view is JIS B0601 (1994). These are values calculated by processing based on specified Ra, and all are values measured using a scanning white interference microscope as a measurement visual field of 0.05 to 0.3 mm □. Specific examples of the scanning white interference microscope include “Zygo New View 6300” and “Zygo New View 7300” manufactured by Zygo Corporation. The arithmetic average roughness and the ten-point average roughness in the macro field of view can be obtained by processing and calculating based on Ra and Rz _JIS defined in JIS B0601 (2001).
Moreover, it is preferable that the ten-point average roughness in the micro visual field on the surface of the optical functional layer is 50 nm or less, and the arithmetic average roughness is 3.0 nm or less. When the ten-point average roughness in the micro field of view exceeds 50 nm, the surface irregularities of the optical functional layer are likely to cause defects such as cracks during film formation of the conductive layer and uneven film thickness, and the conductive layer formed on the optical functional layer. It is difficult to reduce the resistance of the layer, and the variation in resistance value of the conductive layer may increase. When the arithmetic average roughness exceeds 3.0 nm, the surface of the optical functional layer is uneven. Defects such as cracks during film formation and uneven film thickness are likely to occur, and it is difficult to reduce the resistance of the conductive layer formed on the optical functional layer, and the resistance value of the conductive layer may vary greatly. In particular, in a capacitive touch panel, the conductive layer is patterned, but the pattern is thinned (for example, a line width of 1 mm or less) so that the pattern of the conductive layer is difficult to see. Since the pattern is thinned in this way, defects such as cracks during film formation of the conductive layer and uneven film thickness are likely to occur, and it is difficult to achieve low resistance. May not be removed.
A more preferable upper limit of the ten-point average roughness in the micro field of view is 1.0 nm, and a more preferable upper limit of the arithmetic average roughness in the micro field of view is 2.5 nm.
The ten-point average roughness in the micro field of view is a value calculated by processing based on Rz _JIS defined in JIS B0601 (2001), and the arithmetic average roughness in the micro field of view is JIS B0601 (2001). The values calculated by processing on the basis of the prescribed Ra, are all values measured in a measurement visual field of 1 to 10 μm □ using a scanning probe microscope. Specific examples of the scanning probe microscope include SPM-9600 manufactured by Shimadzu Corporation. The arithmetic average roughness and the ten-point average roughness in the micro field of view can be obtained by processing and calculating based on Ra and Rz defined in JIS B0601 (1994).
In the following description, the 10-point average roughness is expressed as “Rz” and the arithmetic average roughness is described as “Ra” in both the macro view and the micro view.

The light-transmitting substrate is not particularly limited, and examples thereof include polyester resins, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, and (meth) acrylic resins. Examples include resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl alcohol resins, polyarylate resins, polyphenylene sulfide resins, and the like. Of these, polyester resins, polycarbonate resins, and polyolefin resins are preferably used.

The thickness of the light transmissive substrate is preferably 15 to 200 μm. If it is less than 15 μm, wrinkles are likely to occur, and when manufacturing the hard coat film for a touch panel of the present invention, it may be difficult to continuously form an undercoat layer or the like on the light transmissive substrate. is there. On the other hand, when the thickness exceeds 200 μm, when the hard coat film for a touch panel of the present invention is produced, the light transmissive substrate cannot be formed into a roll well, which is disadvantageous for the thinning, weight reduction and cost reduction of the touch panel. Sometimes. The thickness of the light transmissive substrate is more preferably a lower limit of 50 μm and a more preferable upper limit of 125 μm.

The light-transmitting substrate may be subjected to an etching treatment or undercoating treatment such as sputtering, corona discharge, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation, etc. on the surface in advance. By performing these treatments in advance, the adhesion with the undercoat layer formed on the light-transmitting substrate can be improved. Moreover, before forming an undercoat layer or a conductive layer, the surface of the light-transmitting substrate may be dust-removed or cleaned by solvent cleaning, ultrasonic cleaning, or the like as necessary.

In the hard coat film for a touch panel of the present invention, the optical functional layer preferably has at least an undercoat layer and a low refractive index layer, and the undercoat layer is preferably laminated on the light transmissive substrate.
It is preferable that the optical functional layer further has a high refractive index layer, and the undercoat layer, the high refractive index layer, and the low refractive index layer are laminated in this order on a light-transmitting substrate.
Hereinafter, a configuration in which the undercoat layer, the high refractive index layer, and the low refractive index layer constituting the optical functional layer are laminated in this order on the light transmissive substrate will be described as a configuration of the present invention.

In the hard coat film for a touch panel of the present invention, the undercoat layer, the high refractive index layer, and the low refractive index layer preferably all contain fine particles.
When the fine particles contained in the undercoat layer are fine particles a, the fine particles contained in the high refractive index layer are fine particles b, and the fine particles contained in the low refractive index layer are fine particles c, the touch panel of the present invention. In the hard coat film, the fine particles a, the fine particles b, and the fine particles c preferably have an average particle diameter satisfying the relationship of the following formula (1).
Average particle size of fine particles a> Average particle size of fine particles b> Average particle size of fine particles c (1)
By satisfying the relationship of the above formula (1), the hard coat film for a touch panel of the present invention is extremely excellent in adhesion between the high refractive index layer and the low refractive index layer, and also excellent in film strength. Can do.
The high refractive index layer and the low refractive index layer contain appropriate amounts of fine particles b and fine particles c so as to have a desired refractive index. When the cross section of each layer is observed, the fine particles b have an average particle size larger than that of the fine particles c. Therefore, the cross-sectional area of the fine particles b appearing in the cross section of the high refractive index layer is the cross section of the low refractive index layer. It becomes smaller than the cross-sectional area of the fine particles c appearing in FIG. This is because the fine particles b in the high refractive index layer are contained more densely, and as a result, at the interface between the high refractive index layer and the low refractive index layer, the high refractive index layer will be described later. It is presumed that the binder resin b to be bonded has more portions in contact with the low refractive index layer, and the adhesion between the high refractive index layer and the low refractive index layer is excellent.
Moreover, since the low refractive index layer containing the fine particles c is a fine particle having the smallest average particle diameter from the above formula (1), the surface of the low refractive index layer (the surface opposite to the high refractive index layer side). The above-described values of Rz and Ra of the uneven shape caused by the fine particles c are small, and the smoothness is extremely excellent. When this low refractive index layer is smooth, when a conductive layer described later is formed, the film formation property of the conductive layer is improved, defects such as cracks and film thickness unevenness are less likely to occur, and resistance is easily reduced and resistance value is reduced. The variation of the can also be suppressed small.
Rz and Ra measured in the micro field of view represent parameters of the uneven shape of the surface of the low refractive index layer due to the fine particles c, and when a conductive layer is formed on the surface of the low refractive index layer, It is preferable that a concavo-convex shape that substantially maintains the concavo-convex shape of the surface of the low refractive index layer is formed on the surface of the conductive layer. The uneven shape caused by the fine particles c on the surface of the low refractive index layer (the surface opposite to the high refractive index layer side) was formed so that Rz and Ra measured in the micro field of view satisfy the relationship described above. In this case, since the smoothness becomes extremely excellent, the values of Rz and Ra of the concavo-convex shape caused by the fine particles c on the surface of the conductive layer are also reduced, and the smoothness is extremely excellent.
In addition, the above-mentioned `` maintenance of the concavo-convex shape on the surface of the low refractive index layer '' means that the parameter indicating the concavo-convex shape on the surface of the low refractive index layer and the parameter indicating the concavo-convex shape on the surface of the conductive layer It means almost the same value. Therefore, the surface of the low refractive index layer is provided with a concavo-convex shape that is equivalent to the concavo-convex shape of the surface of the conductive layer and optical performance such as transparency and interference fringe prevention.

In the hard coat film for a touch panel of the present invention, the average particle diameter of the fine particles a, b and c is a scanning transmission electron microscope (TEM, STEM) obtained by applying the fine particles themselves or a dispersion onto a PET film and drying it. The surface is observed, the arbitrary 10 particles are extracted, the long diameter is measured, the average value is calculated, the same operation is performed 5 times in another screen imaging of the same sample, and a total of 50 particles are measured. It means a value obtained from the number average particle size of the secondary particles. Note that the particle diameters of the high refractive index fine particles and the low refractive index fine particles are primary particles, and thus are obtained in the same manner.
Further, when the particles take the form of aggregated particles, the particle diameter of each aggregated particle is calculated from the average of the major axis and the minor axis of the aggregated particle, and the average is calculated. Specifically, any two aggregated particles from the surface or cross-sectional image of the functional film by an atomic force microscope (AFM) or the surface or cross-sectional image of the functional film by a scanning transmission electron microscope (TEM, STEM). (In the case of the surface, two particles can be selected at random, but in the case of the cross section, it is unclear where the particles are cut, so select the two particles that are as large as possible) Measure the major and minor diameters to calculate the particle size of each agglomerated particle, perform the same operation 9 times in another screen imaging of the same sample, the number average of the particle size of the aggregated particles for a total of 20 particles The value obtained from the above was defined as the average particle size of the aggregated particles. The major axis is the longest diameter on the aggregated particle screen. The minor axis is a distance between two points where a line segment perpendicular to the midpoint of the line segment constituting the major axis is drawn and the perpendicular line segment intersects with the aggregated particles.

In the hard coat film for a touch panel of the present invention, the undercoat layer containing the fine particles a is preferably laminated on the light transmissive substrate.
The fine particles a preferably have a larger average particle diameter than the fine particles b and c. The undercoat layer containing the fine particles a having such a large average particle diameter is laminated on the light-transmitting substrate, so that the hard coat film for a touch panel of the present invention has a low refractive index layer described later. An uneven shape a resulting from the fine particles a can be formed on the surface.
Such a concavo-convex shape a on the surface of the low refractive index layer preferably satisfies Rz and Ra in the macro field of view described above. Moreover, the slidability of the hard coat film for a touch panel of the present invention can be improved by forming the uneven shape a on the surface of the low refractive index layer. From the viewpoint of improving productivity at the time of molding of the hard coat film for touch panel of the present invention due to the excellent slidability of the hard coat film for touch panel of the present invention, the film overlapped when wound up into a roll It is possible to suitably prevent the occurrence of a phenomenon (so-called blocking) in which the two stick together.
Moreover, in the hard coat film for a touch panel of the present invention, even if a concavo-convex shape (high-frequency component) finer than the concavo-convex shape a described later exists on the surface on the undercoat layer, the high-frequency component of the concavo-convex shape. Is filled by forming the above-described high refractive index layer and low refractive index layer on the undercoat layer. For this reason, the uneven | corrugated shape resulting from the high frequency component of the surface of the said undercoat layer is not formed in the surface of the said low-refractive-index layer. Therefore, as described above, when the conductive layer is formed, it is possible to sufficiently obtain the effect that the film forming property is improved, the resistance is easily reduced, and the variation in the resistance value is suppressed to be small.
The fine particles a may be contained in the undercoat layer in the form of single particles, or may be contained in the undercoat layer in the state of aggregated particles, but in any state, The average particle diameter satisfies the above relationship.

The fine particles a are not particularly limited, and examples thereof include organic fine particles and / or inorganic fine particles.
The inorganic fine particles are not particularly limited. For example, inorganic oxide fine particles are suitably used. Examples of the inorganic oxide particles include silica fine particles, alumina fine particles, zirconia fine particles, titania fine particles, tin oxide fine particles, and ATO particles. Zinc oxide fine particles, colloidal silica fine particles, and the like.
As the inorganic fine particles, silica fine particles are more preferable from the viewpoint of heat-and-moisture stability of the undercoat layer, and the surface of the low refractive index layer described later can be formed into a concave and convex shape to easily impart easy slipping. Silica fine particles or colloidal silica fine particles are more preferable.
In addition, the above “spherical” includes, for example, a true spherical shape, an elliptical spherical shape and the like, and has a meaning excluding so-called indefinite shape.

The organic fine particles are not particularly limited, and examples thereof include high-density polyethylene, ultrahigh molecular weight polyethylene having a molecular weight of 300,000 or more, polypropylene, polycarbonate, polyamide, polyester, melamine resin, diallyl phthalate resin, acrylic resin, and co-polymers thereof. Fine particles such as polymers can be mentioned.

The fine particles a contained in the undercoat layer preferably have an average particle size of 0.1 to 3.0 μm. If it is less than 0.1 μm, it may not be possible to form a desired concavo-convex shape on the surface of the low refractive index layer, which will be described later, to impart easy slipping. The film thickness becomes too large with respect to the film thickness, resulting in a cloudy sensation and a loss of transparency. The more preferable lower limit of the average particle diameter of the fine particles a is 0.5 μm, and the more preferable upper limit is 2.0 μm. The average particle diameter of the fine particles a is preferably within the above range not only when the fine particles a are single particles but also when they are contained in the undercoat layer as aggregates.

The undercoat layer preferably contains a binder resin a and fine particles a, and preferably contains 0.05 to 10.0 parts by mass of fine particles a with respect to 100 parts by mass of the binder resin a. . If the amount is less than 0.05 parts by mass, a desired uneven shape may not be formed on the surface of the low refractive index layer to be described later, and slipperiness may not be imparted. The desired uneven shape may not be formed on the surface of the low refractive index layer, and the transparency of the undercoat layer may be lowered. The minimum with more preferable content of the said microparticles | fine-particles a is 0.1 mass part, and a more preferable upper limit is 5.0 mass parts.

The binder resin a is preferably a transparent one, for example, an ionizing radiation curable resin that is a resin curable by ultraviolet rays or an electron beam is preferably one cured by irradiation with ultraviolet rays or an electron beam.
In the present specification, “resin” is a concept including monomers, oligomers, polymers and the like unless otherwise specified.

Examples of the ionizing radiation curable resin include compounds having one or more unsaturated bonds such as compounds having functional groups such as acrylates. Examples of the compound having one unsaturated bond include ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, N-vinylpyrrolidone and the like. Examples of the compound having two or more unsaturated bonds include trimethylolpropane tri (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, and pentaerythritol. Tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) ) Acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, tripentaerythritol octa (meth) acrylate Rate, tetrapentaerythritol deca (meth) acrylate, isocyanuric acid tri (meth) acrylate, isocyanuric acid di (meth) acrylate, polyester tri (meth) acrylate, polyester di (meth) acrylate, bisphenol di (meth) acrylate, diglycerin Polyfunctional compounds such as tetra (meth) acrylate, adamantyl di (meth) acrylate, isoboronyl di (meth) acrylate, dicyclopentane di (meth) acrylate, tricyclodecane di (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate Etc. Among these, pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), and pentaerythritol tetraacrylate (PETTA) are preferably used. In the present specification, “(meth) acrylate” refers to methacrylate and acrylate. In the present invention, as the ionizing radiation curable resin, a compound obtained by modifying the above-described compound with PO, EO or the like can also be used.

In addition to the above compounds, relatively low molecular weight polyester resins having unsaturated double bonds, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, etc. It can be used as an ionizing radiation curable resin.

The ionizing radiation curable resin is used in combination with a solvent-drying resin (a thermoplastic resin or the like, which is a resin that forms a film only by drying the solvent added to adjust the solid content during coating). You can also By using the solvent-drying resin in combination, film defects on the coated surface of the coating liquid can be effectively prevented when the undercoat layer is formed.
The solvent-drying resin that can be used in combination with the ionizing radiation curable resin is not particularly limited, and a thermoplastic resin can be generally used.
The thermoplastic resin is not particularly limited. For example, a styrene resin, a (meth) acrylic resin, a vinyl acetate resin, a vinyl ether resin, a halogen-containing resin, an alicyclic olefin resin, a polycarbonate resin, or a polyester resin. Examples thereof include resins, polyamide-based resins, cellulose derivatives, silicone-based resins, rubbers, and elastomers. The thermoplastic resin is preferably amorphous and soluble in an organic solvent (particularly a common solvent capable of dissolving a plurality of polymers and curable compounds). In particular, from the viewpoint of transparency and weather resistance, styrene resins, (meth) acrylic resins, alicyclic olefin resins, polyester resins, cellulose derivatives (cellulose esters, etc.) and the like are preferable.

The undercoat layer may contain a thermosetting resin.
The thermosetting resin is not particularly limited. For example, phenol resin, urea resin, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin, aminoalkyd resin, melamine-urea cocondensation Examples thereof include resins, silicon resins, polysiloxane resins, and the like.

The undercoat layer containing the fine particles a and the binder resin a is obtained, for example, by applying the composition for an undercoat layer containing the fine particle a, the monomer component of the binder resin a and a solvent onto a light-transmitting substrate. The coating film formed by drying can be formed by curing by ionizing radiation irradiation or the like.

Examples of the solvent contained in the composition for the undercoat layer include alcohols (eg, methanol, ethanol, propanol, isopropanol, n-butanol, s-butanol, t-butanol, benzyl alcohol, PGME, ethylene glycol), ketones (Acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), ethers (dioxane, tetrahydrofuran, etc.), aliphatic hydrocarbons (hexane, etc.), alicyclic hydrocarbons (cyclohexane, etc.), aromatic hydrocarbons ( Toluene, xylene, etc.), halogenated carbons (dichloromethane, dichloroethane, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, etc.), cellosolve acetates, sulfur Kishido compound (dimethylsulfoxide), amides (dimethylformamide, dimethylacetamide, etc.) and the like can be exemplified, or a mixture thereof.

The undercoat layer composition preferably further contains a photopolymerization initiator.
The photopolymerization initiator is not particularly limited, and known ones can be used. Specific examples include, for example, acetophenones, benzophenones, Michler benzoylbenzoate, α-amyloxime ester, thioxanthones, propio Examples include phenones, benzyls, benzoins, and acylphosphine oxides. In addition, it is preferable to use a mixture of photosensitizers, and specific examples thereof include n-butylamine, triethylamine, poly-n-butylphosphine, and the like.

As the photopolymerization initiator, when the binder resin a is a resin system having a radical polymerizable unsaturated group, acetophenones, benzophenones, thioxanthones, benzoin, benzoin methyl ether, etc. are used alone or in combination. Is preferred. When the binder resin a is a resin system having a cationic polymerizable functional group, the photopolymerization initiator may be an aromatic diazonium salt, an aromatic sulfonium salt, an aromatic iodonium salt, a metallocene compound, a benzoin sulfonate ester. Etc. are preferably used alone or as a mixture.

It is preferable that content of the said photoinitiator in the said composition for undercoat layers is 0.5-10.0 mass parts with respect to 100 mass parts of said binder resins a. If it is less than 0.5 parts by mass, the hard coat performance of the undercoat layer to be formed may be insufficient, and if it exceeds 10.0 parts by mass, there is a possibility of inhibiting the curing. It is not preferable.

Although it does not specifically limit as a content rate (solid content) of the raw material in the said composition for undercoat layers, Usually, it is 20-70 mass%, and especially 20-60 from the coating appropriateness of the said composition for undercoat layers. It is preferable to set it as the mass%. The undercoat layer composition is applied to a thickness of several μm, so that if the solid content is too low (that is, the ratio of the solvent contained is high), it is difficult to dry the coating film, and the undercoat layer is formed. Film thickness unevenness is likely to occur. On the other hand, when the solid content of the composition for an undercoat layer is too high, leveling properties are poor, and film thickness unevenness and appearance deterioration tend to occur in the formed undercoat layer.

Depending on the purpose of increasing the hardness of the undercoat layer, suppressing curing shrinkage, controlling the refractive index, etc., the above-mentioned composition for undercoat layer may be a conventionally known dispersant, surfactant, antistatic agent, Silane coupling agent, thickener, anti-coloring agent, coloring agent (pigment, dye), antifoaming agent, leveling agent, flame retardant, UV absorber, adhesion-imparting agent, polymerization inhibitor, antioxidant, surface modification An agent or the like may be added.
As the leveling agent, for example, silicone oil, fluorine-based surfactant, and the like are preferable because the undercoat layer is prevented from having a Benard cell structure. When a resin composition containing a solvent is applied and dried, a surface tension difference or the like is generated between the coating film surface and the inner surface in the coating film, thereby causing many convections in the coating film. The structure generated by this convection is called a Benard cell structure, and causes a problem such as the skin and coating defects in the formed undercoat layer.
Moreover, the said Benard cell structure has a possibility that the unevenness | corrugation of the surface of an undercoat layer may become large too much, and may impair the external appearance of the hard-coat film for touchscreens of this invention. When the leveling agent as described above is used, this convection can be prevented, so that not only an undercoat layer free from defects and unevenness can be obtained, but also the uneven shape on the surface of the undercoat layer can be easily adjusted.

The method for preparing the composition for the undercoat layer is not particularly limited as long as each component can be uniformly mixed. For example, the composition can be performed using a known apparatus such as a paint shaker, a bead mill, a kneader, or a mixer.

The method for applying the undercoat layer composition onto the light-transmitting substrate is not particularly limited. For example, spin coating, dipping, spraying, die coating, bar coating, roll coater, meniscus coater And publicly known methods such as a method, a flexographic printing method, a screen printing method, and a pea coater method.
After applying the composition for an undercoat layer by any of the above methods, it is transported to a heated zone to dry the formed coating film, and the coating film is dried by various known methods to evaporate the solvent. Here, the distribution state of the aggregates of the fine particles a can be adjusted by selecting the solvent relative evaporation rate, solid content concentration, coating solution temperature, drying temperature, drying air speed, drying time, solvent atmosphere concentration in the drying zone, and the like. .
In particular, a method of adjusting the distribution state of the fine particles a by selecting drying conditions is simple and preferable. The specific drying temperature is preferably 30 to 120 ° C., and the drying wind speed is preferably 0.2 to 50 m / s, and the fine particles a can be obtained by performing drying treatment appropriately adjusted within this range once or plural times. Can be adjusted to a desired state.

In addition, as a method of irradiating ionizing radiation when curing the coating film after drying, for example, a light source such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc lamp, a black light fluorescent lamp, or a metal halide lamp is used. A method is mentioned.
Moreover, as a wavelength of an ultraviolet-ray, the wavelength range of 190-380 nm can be used. Specific examples of the electron beam source include various electron beam accelerators such as a cockcroft-wald type, a bandegraft type, a resonant transformer type, an insulated core transformer type, a linear type, a dynamitron type, and a high frequency type.

In the hard coat film for a touch panel of the present invention, for example, the undercoat layer has a hardness of HB or more and 4H or less in a pencil hardness test (load 4.9 N) according to JIS K5600-5-4 (1999). Is more preferable, and H or more is more preferable.
The thickness of the undercoat layer is preferably 0.5 to 8.0 μm. If the thickness is less than 0.5 μm, precipitation of low molecular weight components such as oligomers from the light-transmitting substrate cannot be sufficiently prevented, and the surface of the undercoat layer may be easily damaged, and 8.0 μm If it exceeds, not only the undercoat layer cannot be made thin, but the undercoat layer may be easily broken. A more preferable range of the thickness of the undercoat layer is 1.0 to 5.0 μm. In addition, the thickness of the said undercoat layer can be measured by cross-sectional microscope observation.
The undercoat layer preferably has a refractive index of 1.45 to 1.60. If the refractive index of the undercoat layer is out of the above range, the refractive index difference from the light-transmitting substrate or the like becomes significant, which may cause interference fringes.

The hard coat film for a touch panel of the present invention preferably has another undercoat layer on the side surface opposite to the undercoat layer side of the light transmissive substrate. By having the other undercoat layer, the occurrence of curling of the hard coat film for a touch panel of the present invention can be suppressed, and the generation of scratches in the production process can be reduced.
Moreover, it is also preferable that the functional layer mentioned later is laminated | stacked on the side opposite to the light transmissive base material side of said another undercoat layer.
Furthermore, it is preferable that the other undercoat layer has substantially the same surface asperity shape as the above-described undercoat layer.

The other undercoat layer can be formed using the same material as the above-described undercoat layer. By forming the other undercoat layer as described above, the effects of blocking resistance and slipperiness of the hard coat film for a touch panel of the present invention can be enhanced.

In the hard coat film for a touch panel of the present invention, a high refractive index layer containing fine particles b and a low refractive index layer containing fine particles c are preferably laminated in this order on the undercoat layer.
The hard coat film for a touch panel of the present invention preferably has a predetermined patterned conductive layer as will be described later. However, since it is a member used for a touch panel, the patterned conductive layer is made invisible. According to demand, the hard coat film for a touch panel of the present invention requires strict optical characteristics. For this reason, the high refractive index layer and the low refractive index layer are required to strictly control the thickness and refractive index. Specifically, the high refractive index layer preferably has a thickness of 10 to 100 nm and a refractive index of 1.55 to 1.75, and the low refractive index layer has a thickness of 10 to 100 nm and a refractive index of 1. It is preferable that it is 35-1.55. The thickness of the high refractive index layer and the low refractive index layer is more preferably 30 to 70 nm.
In the hard coat film for a touch panel of the present invention, the high refractive index layer, the undercoat layer, and the low refractive index layer preferably have a refractive index satisfying the relationship of the following formula (2). By satisfy | filling following formula (2), the invisibility of the conductive layer formed on the said low-refractive-index layer can be aimed at suitably.
Refractive index of high refractive index layer> Refractive index of undercoat layer> Refractive index of low refractive index layer (2)
In addition, the hard coat film for touch panels of this invention may have functional layers, such as an adhesion layer and an inorganic layer, directly under a conductive layer. The inorganic layer will be described in detail later.
The method for forming the high refractive index layer and the low refractive index layer can be broadly classified into a wet method and a dry method, but the wet method is preferably used because it is excellent in terms of production efficiency.

Examples of the high refractive index layer include those containing a binder resin b and fine particles b.
As the fine particles b, particles having a desired refractive index may be appropriately selected. Examples of particles having a relatively high refractive index include zinc oxide (1.90), titanium oxide (2.3 to 2.7), cerium oxide (1.95), and tin-doped indium oxide (1.95 to 2.95). 00), antimony-doped tin oxide (1.75 to 1.85), yttrium oxide (1.87), zirconium oxide (2.10) and the like. In addition, the inside of the said parenthesis shows the refractive index of the material of each particle. Among these, the fine particles b are preferably zirconium oxide fine particles, and the fine particles b are more preferably amorphous zirconium oxide fine particles from the viewpoint of inclusion in the high refractive index layer. Due to the amorphous zirconium oxide fine particles, it is difficult to close-pack in the high refractive index layer, the contact ratio between the binder resin a and the low refractive index layer in the high refractive index layer is increased, and the adhesion between these layers is increased. Leads to improvement.

The average particle diameter of the fine particles b is preferably 15 to 50 nm. If the thickness is less than 15 nm, the amount of the fine particles b added to increase the refractive index of the high refractive index layer may increase, and the fine particles b are uniformly dispersed in the high refractive index layer. Therefore, the interlaminar adhesion between the high refractive index layer and the low refractive index layer may be inferior. On the other hand, when the thickness exceeds 50 nm, a large uneven shape due to the fine particles b is formed on the surface of the high refractive index layer, and when a conductive layer described later is formed on the low refractive index layer, Defects such as cracks and film thickness unevenness are likely to occur, it is difficult to reduce resistance, and the variation in resistance value may increase. A more preferable lower limit of the average particle diameter of the fine particles b is 20 nm, and a more preferable upper limit is 35 nm.

The binder resin b is not particularly limited. For example, a thermoplastic resin can be used. From the viewpoint of increasing the surface hardness, a curable resin such as a thermosetting resin composition or an ionizing radiation curable resin composition. What is formed from a composition is preferable, and what is formed from an ionizing radiation curable resin composition among these is more preferable.
Examples of the thermosetting resin composition include curable resins such as acrylic resins, urethane resins, phenol resins, urea melamine resins, epoxy resins, unsaturated polyester resins, and silicone resins, and curing agents that are added as necessary. Or a monomer comprising the curable resin and a curing agent.

Examples of the ionizing radiation curable resin of the ionizing radiation curable resin composition include compounds having one or more unsaturated bonds, such as a compound having an acrylate or methacrylate functional group. Examples of such a compound include the same compounds as the ionizing radiation curable resin described as the binder resin for the undercoat layer.

In addition, these compounds may have a refractive index adjusted to be high by introducing an aromatic ring, a halogen atom other than fluorine, sulfur, nitrogen, phosphorus atoms, or the like.
In addition to the above compounds, relatively low molecular weight polyester resins having unsaturated double bonds, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, etc. Can also be used as an ionizing radiation curable resin composition.

When the ionizing radiation curable resin composition is cured by ultraviolet irradiation, it is preferable that the composition contains an additive such as a photopolymerization initiator or a photopolymerization accelerator.
Examples of the photopolymerization initiator include acetophenone, benzophenone, Michler ketone, benzoin, benzyl methyl ketal, benzoyl benzoate, α-acyl oxime ester, α-hydroxy ketone, and thioxanthone. In the present invention, from the viewpoint of increasing the hardness of the high refractive index layer and the low refractive index layer, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropionyl) benzyl] phenyl} -2- Methylpropan-1-one is preferred.
The photopolymerization accelerator is capable of reducing the polymerization obstacle due to air during curing and increasing the curing speed. For example, p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, etc. Is mentioned.

In the hard coat film for a touch panel of the present invention, the high refractive index layer preferably contains 100 to 300 parts by mass of fine particles b with respect to 100 parts by mass of the binder resin b. When the amount is less than 100 parts by mass, the refractive index of the high refractive index layer may be insufficient. When the amount exceeds 300 parts by mass, the fine particles are formed at the interface between the high refractive index layer and the low refractive index layer. In some cases, a region where neither b nor the above-mentioned fine particles c is present can be formed sufficiently, and the interlaminar adhesion between the high refractive index layer and the low refractive index layer may be inferior. Moreover, since there are few said binder resin b components, the coupling | bonding effect of binder resin b may become thin, a high refractive index layer may become easy to peel or hardness may become low. The more preferable lower limit of the content of the fine particles b is 150 parts by mass, and the more preferable upper limit is 250 parts by mass.

Examples of the low refractive index layer include those containing a binder resin c and fine particles c.
As the binder resin c, the binder resin b exemplified in the high refractive index layer can be used. Further, a resin having a low refractive index such as a resin into which fluorine atoms are introduced or organopolysiloxane may be mixed as the binder resin c.
Examples of the fine particles c used for the low refractive index layer include silica fine particles, magnesium fluoride fine particles, and hollow particles thereof. Silica fine particles are preferable, and colloidal silica fine particles are more preferable. Because of the colloidal silica fine particles, from the viewpoint of dispersion stability, a colloidal solution in which colloidal silica is dispersed in an organic solvent is preferably used when forming the low refractive index layer. From the viewpoint, reactive silica particles having a reactive functional group on the surface can be used. The reactive silica particles can form a crosslinked structure with the binder resin c, and the hardness of the low refractive index layer to be formed can be extremely excellent.

The average particle diameter of the fine particles c is preferably 5 nm or more and less than 30 nm. When the thickness is less than 5 nm, aggregation may easily occur, and it may be difficult to uniformly disperse in the composition for a low refractive index layer. On the other hand, when the thickness exceeds 30 nm, there may be a case where the uneven shape c that satisfies the parameters due to the fine particles c described above cannot be formed on the surface of the low refractive index layer. The more preferable lower limit of the average particle diameter of the fine particles c is 10 nm, and the more preferable upper limit is 15 nm.

In the hard coat film for a touch panel of the present invention, the low refractive index layer preferably contains 50 to 150 parts by mass of fine particles c with respect to 100 parts by mass of the binder resin c. If it is less than 50 parts by mass, the refractive index of the low refractive index layer may be insufficient. On the other hand, when it exceeds 150 parts by mass, defects such as cracks during film formation of the low refractive index layer and film thickness unevenness tend to occur, and it is difficult to reduce the resistance of the conductive layer formed on the low refractive index layer. In some cases, the variation in resistance value of the conductive layer also increases. Further, since the binder resin c component in the low refractive index layer is small, the binding effect of the binder resin c is weakened, the low refractive index layer is easily peeled off (does not become a low refractive index layer), and the hardness may be low. .
The minimum with more preferable content of the said fine particle c is 75 mass parts, and a more preferable upper limit is 125 mass parts.

In the hard coat film for a touch panel of the present invention, a conductive layer is preferably formed on the side surface of the low refractive index layer opposite to the high refractive index layer.
The material constituting the conductive layer is not particularly limited, and for example, selected from the group consisting of indium, tin, zinc, gallium, antimony, titanium, silicon, zirconium, magnesium, aluminum, gold, silver, copper, palladium, and tungsten. A metal or metal oxide containing at least one metal element is preferably used. The metal oxide may further contain a metal atom shown in the above group, if necessary. For example, indium oxide (ITO) containing tin oxide and tin oxide (ATO) containing antimony are preferably used.

The thickness of the conductive layer is not particularly limited, but it is preferably 10 nm or more, more preferably 15 nm or more from the viewpoint of securing good conductivity, preferably 300Ω / □ or less, more preferably 150Ω / □ or less. 20 nm or more is more preferable. On the other hand, if the thickness of the conductive layer becomes too large, the above-described effect of invisibility by the high refractive index layer and the low refractive index layer may be reduced, and inconvenience that transparency may be reduced may occur. The thickness of the layer is preferably 60 nm or less, more preferably 50 nm or less, and still more preferably 40 nm or less.

In the hard coat film for a touch panel of the present invention, when the conductive layer is made of the metal oxide described above, the refractive index of the conductive layer is preferably 1.81 or more, more preferably 1.85 or more. More preferably, 90 or more. The upper limit of the refractive index of the conductive film is preferably 2.20 or less, and more preferably 2.10 or less.

It does not specifically limit as a formation method of the said conductive layer, 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. In addition, an appropriate method can be adopted depending on the required film thickness.
In the hard coat film for a touch panel of the present invention, the conductive layer is laminated on the low refractive index layer (or an inorganic layer having an uneven surface shape that substantially maintains the uneven shape of the low refractive index layer). For example, when the conductive layer is formed on the low refractive index layer or the like by a dry process such as sputtering, the surface of the formed conductive layer satisfies the relationship of Rz and Ra described above. It is possible to have a concavo-convex shape a resulting from the fine particles a contained in. Therefore, sufficient slipperiness can be imparted to the surface of the conductive layer formed on the low refractive index layer or the like.
In addition, when the surface of the low refractive index layer has a concavo-convex shape c that satisfies the parameters due to the fine particles c, the film strength of the low refractive index layer is excellent. The resistance of the conductive layer can be reduced. The reason for this will be described later.

Since the hard coat film for a touch panel of the present invention is suitably used for a capacitive touch panel, the conductive layer is preferably patterned. Such a patterned conductive layer can be obtained, for example, by patterning the conductive layer formed by the above-described method.
Note that pattern portions and non-pattern portions are formed by patterning the conductive layer. Examples of the shape of the pattern portion include a stripe shape and a lattice shape.

The patterning of the conductive layer is generally performed by etching. For example, the conductive layer is patterned by forming a patterned etching resist film on the conductive layer by a photolithography method, a laser exposure method, or a printing method and then performing an etching process.

A conventionally well-known thing is used as said etching liquid. For example, an inorganic acid such as hydrogen chloride, hydrogen bromide, sulfuric acid, nitric acid or phosphoric acid, an organic acid such as acetic acid, a mixture thereof, an aqueous solution thereof, or the like is used.

The conductive layer can be crystallized by heat treatment, if necessary.
By crystallizing the conductive layer, the resistance of the conductive layer is reduced, and transparency and durability are improved.
Note that when the conductive layer is patterned by the above-described etching, if the conductive layer is crystallized first, patterning by etching may be difficult. For this reason, the heat annealing treatment of the conductive layer is preferably performed after patterning the conductive layer.

In the hard coat film for a touch panel of the present invention, the film thickness of the low refractive index layer, the high refractive index layer and the conductive layer is selected from any two points in the TEM and STEM cross-sectional observation photographs, and the thickness is measured. The same operation is performed nine times on different screens of the same sample, and the average value of film thicknesses for a total of 10 points is calculated as the film thickness value (nm).
The film thicknesses other than the low refractive index layer, the high refractive index layer, and the conductive layer (thickness of a hard coat film, etc.) are also measured using the measurement method described above if the film is a thin film of the order of nm. Is calculated.
In the hard coat film for a touch panel of the present invention, the refractive indexes of the low refractive index layer and the high refractive index layer were measured with a spectrophotometer when the refractive index in the wavelength region of 380 nm to 780 nm was constant. It is calculated by fitting the reflection spectrum and the spectrum calculated from the optical model of the thin film using the Fresnel equation.

Here, in the hard coat film for a touch panel of the present invention, it is preferable that the concavo-convex shape c resulting from the fine particles c formed on the surface of the low refractive index layer satisfies the predetermined parameter described above. Since the uneven shape c satisfying such parameters is excellent in smoothness, when an inorganic layer is formed on the low refractive index layer, the film formation uniformity of the inorganic layer is high and flat. It will be a thing. Such a flat inorganic layer with high uniformity of film formation has extremely excellent gas barrier properties, and the conductive layer laminated on the inorganic layer is less likely to cause unevenness when the conductive layer is formed. As a result, the in-plane distribution of the resistance value of the conductive layer becomes good, and the resistance of the conductive layer can be reduced.

In the hard coat film for a touch panel of the present invention, the conductive layer may be provided on both sides of the light transmissive substrate. In this case, one conductive layer is provided on the light-transmitting substrate via a low refractive index layer having a predetermined uneven shape on the surface, but the other conductive layer is formed on the light-transmitting substrate. It may be directly provided on the light-transmitting substrate, or may be provided on the light-transmitting substrate via the other undercoat layer. That is, the other conductive layer may be provided directly on the side opposite to the low refractive index layer side having a predetermined uneven shape on the above-described surface of the light-transmitting substrate. The coating layer may be provided on the side surface opposite to the light transmissive substrate.
Here, when the hard coat film for a touch panel of the present invention is a wound body in which a long sheet as described later is wound in a roll shape, the one conductive layer and the other conductive layer are in direct contact with each other. It will be in the state. When the conductive layers are in direct contact with each other in this way, there is a problem of adhesion between the conductive layers (blocking property or easy slipperiness) or scratching of the conductive layer when the conductive layer is made of a metal material. On the other hand, in the hard coat film for a touch panel of the present invention, a predetermined uneven shape is formed on the surface of the conductive layer, and excellent blocking resistance and slipperiness are imparted. Even in this case, adhesion between the conductive layers provided on both sides of the light-transmitting substrate (blocking property and easy slipperiness) does not become a problem, and the problem of scratches on the conductive layer is also effectively prevented. it can.

In the hard coat film for a touch panel of the present invention, an inorganic layer is preferably formed between the low refractive index layer side and the conductive layer.
The inorganic layer serves to prevent gas (such as water vapor) contained in the above-described undercoat layer, high refractive index layer, and low refractive index layer from being transferred to the conductive layer during the production of the hard coat film for a touch panel of the present invention. It is a layer that functions as a layer that fulfills. Since the hard coat film for a touch panel of the present invention has the inorganic layer, a gas such as water vapor contained in the low refractive index layer or the like in the conductive layer affects the conductive layer, and the resistance value of the conductive layer Can be suitably prevented. In addition, when the said inorganic layer is formed, it is preferable that the uneven | corrugated shape which substantially maintained the uneven | corrugated shape of the surface of the said low refractive index layer is formed in the surface of this inorganic layer.
As described above, “the uneven shape on the surface of the low refractive index layer is substantially maintained”.

In the hard coat film for a touch panel of the present invention, the material constituting the inorganic layer is not particularly limited, and a conventionally known material can be used, and examples thereof include silica and magnesium fluoride. Of these, silica is preferably used.
Moreover, the said inorganic layer can be formed in the surface on the opposite side to the high refractive index layer side of the said low refractive index layer by a conventionally well-known method, The thickness etc. are not specifically limited.

The hard coat film for a touch panel of the present invention can be a wound body in which a long sheet is wound in a roll shape. The wound body of the long sheet of the hard coat film for a touch panel of the present invention uses a roll-shaped wound body of a long sheet as a light-transmitting substrate, and the undercoat layer, the high refractive index layer, and the low refractive index layer. The conductive layer can be formed by a roll-to-roll method. In forming such a wound body, a protective film provided with a weak adhesive layer may be bonded to the surface of the hard coat film for a touch panel as a separator and then wound into a roll shape. Since the hard coat film for a touch panel can improve the blocking resistance and the slipperiness, it is possible to form a wound body of a long sheet of the hard coat film for a touch panel without using the protective film.

The hard coat film for a touch panel of the present invention can be applied to, for example, an optical system, an ultrasonic system, a capacitive system, a resistive film type touch panel, etc., among which can be suitably applied to a capacitive touch panel.
Such a touch panel using the hard coat film for a touch panel of the present invention is also one aspect of the present invention.

In forming the touch panel of the present invention, another transparent substrate such as glass or a polymer film can be bonded to one or both main surfaces of the hard coat film for a touch panel of the present invention via an adhesive layer. For example, you may form the laminated body by which the transparent base | substrate was bonded together through the transparent adhesion layer on the surface in which the low-refractive-index layer and the conductive layer are not formed in the hard-coat film for touchscreens. The transparent substrate may be composed of a single substrate film, or may be a laminate of two or more substrate films (for example, laminated via a transparent adhesive layer). Moreover, a hard-coat layer can also be provided in the outer surface of the transparent base | substrate bonded to the hard-coat film for touch panels.

The adhesive layer used for bonding the hard coat film for touch panel and the transparent substrate is not particularly limited as long as it has transparency. Specifically, for example, acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyvinyl ethers, vinyl acetate / vinyl chloride copolymers, modified polyolefins, epoxy systems, fluorine systems, natural rubbers, rubbers such as synthetic rubbers, etc. Those having the above polymer as a base polymer can be appropriately selected and used. In particular, an acrylic pressure-sensitive adhesive is preferably used from the viewpoint that it is excellent in optical transparency, exhibits adhesive properties such as appropriate wettability, cohesiveness and adhesiveness, and is excellent in weather resistance and heat resistance.

Since the hard coat film for a touch panel of the present invention can be excellent in blocking resistance and slipperiness as described above, it can be efficiently produced by a roll-to-roll method. Furthermore, since the low refractive index layer in the hard coat film for a touch panel of the present invention has a very smooth shape on the surface, the conductive layer laminated thereon is less likely to cause unevenness during film formation. The in-plane distribution of the resistance value of the conductive layer becomes good.

Since the hard-coat film for touchscreens of this invention consists of an above-described structure, while being excellent in blocking resistance and slipperiness | lubricity, it can aim at the low resistance value of a conductive layer.
For this reason, the hard-coat film for touchscreens of this invention can be applied suitably for a touchscreen, especially an electrostatic capacitance type touchscreen.

The contents of the present invention will be described with reference to the following examples, but the contents of the present invention should not be construed as being limited to these embodiments.

<Measurement and evaluation of physical properties of hard coat film for touch panel>
The physical property measurement and evaluation of the hard coat film for touch panels obtained in Examples, Comparative Examples and Reference Examples were performed as follows. The results are shown in Table 1.

[Surface shape]
When the measurement field of view (measurement area) is 0.12 mm □, the low refractive index of the obtained optical laminate is based on the data of the surface shape measured with a scanning white interference microscope (trade name New View 6300, manufactured by Zygo). Ra and Rz of the rate layer were calculated. Table 1 shows the average values of the measured values at 10 locations. In the case of a measurement field of view (measurement area) of 5 μm □, the Ra of the low refractive index layer of the obtained optical laminate is obtained based on the surface shape data measured with a scanning probe microscope (SPM-9600, manufactured by Shimadzu Corporation). And Rz were calculated. Table 1 shows the average values of the measured values at 10 locations.

[Blocking resistance]
The hard coat film for a touch panel obtained in each example, comparative example and reference example was cut into a size of 5 cm × 5 cm. One side of the hard coat film for touch panel provided with only the undercoat layer and the other side of the hard coat film for touch panel are overlapped so as to face each other, and the pressure is 3.0 kgf / cm ² , 50 After adhesion for 30 hours under the condition of ° C., the following criteria were evaluated.
○: Without sticking ×: With sticking

[Ease of slipperiness]
The hard coat film for a touch panel obtained in each example, comparative example and reference example was cut into a size of 10 cm × 10 cm. Check the slipperiness by overlaying and rubbing the side of the hard coat film for one touch panel with the undercoat layer only on the side of the low refractive index layer of the other hard coat film for the touch panel. The slipperiness was evaluated according to the following criteria.
○: Good slipperiness, no sticking, and good slipperiness.
X: The slipperiness was insufficient, sticking occurred in part, and the slipperiness was poor.

[Surface resistivity]
A transparent conductive film (thickness 25 nm) made of indium tin oxide (ITO) by sputtering under the following conditions on the low refractive index layer of the hard coat film for touch panel obtained in each example, comparative example and reference example. Formed. Thereafter, an annealing treatment is performed at 150 ° C. for 30 minutes to form a conductive layer. Using a surface resistance meter (Loresta MCP: four-terminal probe) manufactured by Mitsubishi Chemical Corporation, JIS R1637 (Resistivity test method for fine ceramic thin film: The surface resistivity was measured based on the 4-probe method) and evaluated according to the following criteria.
○: Surface resistivity is less than 150Ω / □ ×: Surface resistivity is 150Ω / □ or more

[Visibility (cloudiness)]
The surface opposite to the low refractive index layer of each touch panel hard coat film obtained in each Example, Comparative Example and Reference Example was attached to a black acrylic plate via a transparent adhesive, and a table stand (3 The cloudiness was observed under the wavelength fluorescent lamp tube) and evaluated according to the following criteria.
○: Whiteness was not observed.
X: Whiteness was observed.

Example 1
On one surface of a biaxially stretched polyester film (Toyobo Co., Ltd., A4300; with a primer layer) having a thickness of 100 μm, an undercoat layer coating solution having the following formulation was applied so that the thickness after drying was 1.5 μm. Then, the coating film was dried and irradiated with ultraviolet rays to form an undercoat layer (refractive index 1.52 pencil hardness H). The irradiation amount of ultraviolet rays was 300 mJ / cm ² , and the drying conditions of the coating film were 70 ° C. and 60 seconds.
Moreover, on the other surface of the biaxially stretched polyester film, using an undercoat layer coating solution of the following formulation, an undercoat layer is formed under the same conditions as the undercoat layer formed on the one surface, Next, a high refractive index layer (thickness 50 nm, refractive index 1.66) and a low refractive index layer (thickness 30 m, refractive index 1.49) were continuously formed inline on the other surface of the biaxially stretched polyester film. It formed on the undercoat layer and the hard-coat film for touchscreens was obtained.
In addition, the following were used for the coating liquid of the high refractive index layer and the low refractive index layer.
The drying conditions for the high refractive index layer were 50 ° C. and 60 seconds, and the drying conditions for the low refractive index layer were 50 ° C. and 60 seconds. Further, after drying the undercoat layer, the high refractive index layer, and the low refractive index layer, each was irradiated with ultraviolet rays (100 mJ / cm ² ).

(Sputtering conditions)
A thickness of 25 nm by reactive sputtering at a discharge output of 5 W / cm ² while heating at a temperature of 100 ° C. in an atmosphere of 0.5 Pa composed of 99 vol% argon gas and 1 vol% oxygen gas. A transparent conductive film (with a refractive index of light of 2.00) was formed.

<Undercoat layer coating solution>
Dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd., DPHA) 50 parts photopolymerization initiator (manufactured by BASF, Irgacure 184) 2 parts silicone leveling agent (manufactured by Daiichi Seika Kogyo Co., Ltd., Seika Beam 10-28, solid content 10) %) 0.1 part fine particle a-containing liquid 0.3 part methyl isobutyl ketone 60 parts cyclohexanone 15 parts Note that the fine particle a-containing liquid is acrylic resin fine particles (MX-180TA, manufactured by Soken Chemical Co., Ltd., average particle diameter 1.8 μm). ) Is dispersed in methyl isobutyl ketone to a solid content of 15%.

<High refractive index layer coating solution>
Pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD-PET-30) 10 parts photopolymerization initiator (manufactured by BASF, Irgacure 127) 0.7 parts silicone leveling agent (manufactured by Dainichi Seika Kogyo Co., Ltd., Seika Beam 10- 28, solid content 10%) 0.3 parts fine particle b-containing liquid 50 parts methyl isobutyl ketone 500 parts cyclohexanone 250 parts methyl ethyl ketone 500 parts The fine particle b-containing liquid is a zirconium oxide dispersion (Sumitomo Osaka Cement Co., Ltd., solid content 32). 0.5%, average particle size 27 nm).

<Low refractive index layer coating solution>
Pentaerythritol triacrylate (manufactured by Nippon Kayaku Co., Ltd., KAYARAD-PET-30) 5 parts photopolymerization initiator (manufactured by BASF, Irgacure 127) 1 part silicone leveling agent (manufactured by Daiichi Seika Kogyo Co., Ltd., Seika Beam 10-28) (Solid content 10%) 0.2 parts fine particle c-containing liquid 15 parts methyl isobutyl ketone 1000 parts cyclohexanone 250 parts In addition, the fine particle c-containing liquid is a colloidal silica fine particle dispersion (manufactured by Nissan Chemical Industries, solid content 30%, average particle Diameter 10-15 nm) was used.

(Example 2)
A hard coat film for a touch panel was obtained in the same manner as in Example 1 except that the amount of fine particles a in Example 1 was changed to 1.0 part.

(Example 3)
The fine particle a in Example 1 was changed to a colloidal silica fine particle dispersion (manufactured by Nissan Chemical Industries, solid content 30%, average particle size 45 nm) with methyl isobutyl ketone to a solid content of 15%, and the blending amount was 17 A hard coat film for a touch panel was obtained in the same manner as in Example 1 except that the part was changed to the part.

Example 4
A hard coat film for a touch panel was obtained in the same manner as in Example 1 except that the amount of the fine particles a in Example 3 was changed to 34 parts.

(Comparative Example 1)
The fine particle a was removed from the undercoat layer coating solution of Example 1, and the silica fine particle dispersion (manufactured by CIK Nanotech Co., Ltd., solid content 30%, average particle size 30 nm, average aggregate size 150) was added to the high refractive index coating solution. A hard coat film for a touch panel was obtained in the same manner as in Example 1 except that 1.4 parts of (100 to 200) nm) were added.

(Reference Example 1)
The fine particle a of Example 1 was changed to a colloidal silica fine particle dispersion (manufactured by Nissan Chemical Industries, solid content 30%, average particle size 45 nm) with methyl isobutyl ketone to a solid content of 15%, and the blending amount was 100. A hard coat film for a touch panel was obtained in the same manner as in Example 1 except that the part was changed to the part.

As shown in Table 1, the hard coat film for a touch panel according to the example has an arithmetic average roughness (Ra) of 0.5 to 10.0 nm and a ten-point average roughness in a macro view (0.12 mm □ view). (Rz) is in the range of 50 to 500 nm, Ra in the micro field of view (5 μm square field) is 3.0 nm or less, Rz is 50 nm or less, and Ra and Rz in the macro field are both Ra and Rz in the micro field. Since it was larger than the above, it has excellent blocking resistance without impairing the cloudiness, and the conductive layer has good film formability, no defects such as cracks and uneven film thickness, and low resistance. Met.
On the other hand, since the hard coat film for a touch panel according to Comparative Example 1 did not contain the fine particles a, the uneven shape (uneven shape a) in the macro view (0.12 mm □ view) was not sufficiently formed on the surface of the conductive layer. Ra and Rz in the macro field of view were smaller than Ra and Rz in the micro field of view (5 μm □ field of view), and blocking resistance, easy slipping, and low resistance could not be achieved.
In addition, the hard coat film for touch panel according to Reference Example 1 has large Ra and Rz of 10.5 nm and 543 nm in the macro field of view (0.12 mm □ field of view), respectively, and Ra in the micro field of view (5 μm □ field of view). Since the film thickness was 4.5 nm, the film-forming property of the conductive layer deteriorated, and defects such as cracks and film thickness unevenness occurred. As a result, the resistance could not be reduced, and the visibility was poor. It was.

The hard coat film for a touch panel of the present invention can be suitably applied to a touch panel, particularly a capacitive touch panel.

Claims (13)

A hard coat film for a touch panel in which an optical functional layer is laminated on a light-transmitting substrate,
The optical functional layer has an uneven shape on the surface,
Using a scanning white interference microscope, the ten-point average roughness and arithmetic average roughness values of the concave and convex shapes of the optical functional layer measured as a measuring field of 0.12 mm □ are both measured using a scanning probe microscope. A hard coat film for a touch panel, which is larger than the values of the ten-point average roughness and arithmetic average roughness of the irregular shape of the optical functional layer measured as 5 μm □. The ten-point average roughness of the concave and convex shape of the optical functional layer measured using a scanning white interference microscope with a measurement visual field of 0.12 mm □ is 50 to 500 nm, and the arithmetic average roughness of the concave and convex shape of the optical functional layer is 0 The hard coat film for a touch panel according to claim 1, which has a thickness of 5 to 10.0 nm. The ten-point average roughness of the irregular shape of the optical functional layer measured using a scanning probe microscope with a measurement field of view of 5 μm □ is 50 nm or less, and the arithmetic average roughness of the irregular shape of the optical functional layer is 3. The hard coat film for a touch panel according to claim 1, which is 0 nm or less. The hard coat film for a touch panel according to claim 1, wherein the optical functional layer has at least an undercoat layer and a low refractive index layer, and the undercoat layer is laminated on the light-transmitting substrate. The hard coat for a touch panel according to claim 4, wherein the optical functional layer further has a high refractive index layer, and an undercoat layer, a high refractive index layer, and a low refractive index layer are laminated in this order on a light-transmitting substrate. the film. The undercoat layer contains fine particles a, the high refractive index layer contains fine particles b, the low refractive index layer contains fine particles c,
The touch panel hardware according to claim 5, wherein the fine particles a have an average particle size of 0.1 to 3.0 μm, the fine particles b have an average particle size of 15 to 50 nm, and the fine particles c have an average particle size of 5 nm or more and less than 30 nm. Coat film. The fine particles a contained in the undercoat layer are silica fine particles, the fine particles b contained in the high refractive index layer are zirconium oxide fine particles, and the fine particles c contained in the low refractive index layer are silica fine particles. The hard coat film for a touch panel according to claim 6. Fine particles a contained in the undercoat layer are spherical silica fine particles or colloidal silica fine particles, and fine particles b contained in the high refractive index layer are amorphous zirconium oxide fine particles, and fine particles contained in the low refractive index layer. The hard coat film for a touch panel according to claim 7, wherein c is a colloidal silica fine particle. The hard coat film for a touch panel according to claim 6, 7 or 8, wherein a region where neither fine particles b nor fine particles c exist is formed at an interface between the high refractive index layer and the low refractive index layer. The refractive index of the undercoat layer is 1.45 to 1.60, the refractive index of the high refractive index layer is 1.55 to 1.75, and the refractive index of the low refractive index layer is 1.35 to 1.55. And
The hard coat film for a touch panel according to claim 5, 6, 7, 8, or 9, wherein each of the high refractive index layer, the undercoat layer, and the low refractive index layer satisfies a relationship represented by the following formula (2). .
Refractive index of high refractive index layer> Refractive index of undercoat layer> Refractive index of low refractive index layer (2) The hard coat film for a touch panel according to claim 5, wherein a conductive layer is formed on a side surface of the low refractive index layer opposite to the high refractive index layer side. The hard coat film for a touch panel according to claim 11, wherein an inorganic layer is formed between the low refractive index layer and the conductive layer. A touch panel comprising the hard coat film for a touch panel according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12.