JP6182448B2 - Capacitive touch panel - Google Patents

Description

  The present invention relates to a capacitive touch panel, and more particularly to a capacitive touch panel that can shorten the time required for visual recognition and can be input by touching a finger.

  In recent years, touch panels are rapidly spreading as input devices that replace key switches. A touch panel inputs a signal to a device by touching a cover panel on which a sensor is arranged with a conductive material such as a finger or a pen. Among them, capacitive touch panels that detect changes in capacitance between the fingertip and the conductive film are various types of tablet-type mobile terminals such as smart phones, tablet-type personal computers, and automobiles. Widely used in car navigation systems and car audio systems.

A capacitive touch panel detects a position by detecting a change in electrostatic capacitance between a fingertip and a conductive film, and the touch panel is also used for car navigation systems, car audio systems, and the like for automobiles.
However, the surface of the touch panel is usually formed of a flat glass substrate or a flat transparent sheet such as polycarbonate resin, and it is necessary to operate with fingers while visually confirming the operation. For example, driving a car It is very dangerous to operate while viewing inside.

  For example, Patent Document 1 discloses a protective transparent substrate having an observation side surface and a display device side surface, and two polymer films with electrode layers for position detection disposed on the display device side surface of the protective transparent substrate. A capacitive touch panel has been proposed. And it is described that a glass base material, a polymethylmethacrylate base material, and a polycarbonate base material can be used as the said protective transparent base material, and it is preferable to use a glass base material from the point of rigidity. However, the glass substrate is heavy and has a problem that it is easily broken because of its thin thickness. On the other hand, the polymethyl methacrylate base and the polycarbonate base have advantages in terms of weight reduction, but particularly the polymethyl methacrylate base has a problem of poor impact resistance.

  Also, in car navigation systems and car audio touch panels for automobiles, separate operation buttons such as on / off are usually provided on the outer periphery, but if these can also be incorporated in the touch panel, the number of parts can be reduced. This is advantageous in terms of improving functionality or design. Further, by incorporating the operation button in the touch panel, there is an advantage that the problem of durability of the button is eliminated. In this case, it is conceivable that the conventional button portion has the same convex portion in the touch panel or a concave portion on the contrary.

  However, since the polymethyl methacrylate base and the polycarbonate base used for the protective transparent base are usually manufactured by extrusion molding, sheet molding, and film molding, only flat molded bodies can be manufactured. It has been difficult to impart a desired shape such as a recess to the cover panel of the base material. In order to give the cover panel a desired shape such as a convex part or a concave part, it may be possible to adopt an injection molding method instead of an extrusion molding method or the like. When injection molding is performed, the flow state of the molten resin changes at the stepped part of the convex part or the concave part, and birefringence is likely to occur due to shearing. On the touch panel, retardation unevenness due to birefringence is likely to occur, and display is performed. It tends to cause a reduction in image color balance and contrast. In the state where the birefringence is large, there is a problem that the screen is blacked out and cannot be visually recognized particularly when the screen is viewed with polarized sunglasses.

Japanese Unexamined Patent Publication No. 2012-033135

  The object (problem) of the present invention is that, as described above, there is no blackout due to birefringence when viewed through polarized sunglasses, the appearance is good, the time required for visual recognition can be shortened, and input can be made with the tactile sensation of fingers. The object is to provide a capacitive touch panel with excellent operability.

As a result of intensive studies in order to achieve the above-mentioned problems, the present inventors have obtained a copolymer component containing α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or a derivative thereof in polycarbonate resin. It was found that a capacitive touch panel having a cover panel having a convex part or a concave part, which was injection-molded with a polycarbonate resin composition containing a styrene-based resin, solved the above-mentioned problems, and completed the present invention. It was.
The present invention provides the following capacitive touch panel.

[1] A capacitive touch panel having a cover panel having a convex part and / or a concave part that allows the position of the touch sensor to be recognized by tactile sensation, wherein the cover panel is based on 100 parts by mass of the polycarbonate resin (A). , [Alpha], [beta] -unsaturated dicarboxylic acid, [alpha], [beta] -unsaturated dicarboxylic acid anhydride or a derivative thereof, a styrene-based resin (B) containing 30 to 230 parts by mass of a polycarbonate resin composition (C) Capacitive touch panel characterized by being formed by injection molding.
[2] In the above [1], the amount of α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or derivative thereof in the polycarbonate resin composition (C) is 1 to 10% by mass. The capacitive touch panel described.
[3] The above [1] or [3], wherein the amount of α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or derivative thereof in the styrene resin (B) is 1 to 35% by mass. 2].
[4] The capacitive touch panel according to any one of [1] to [3], wherein the polycarbonate resin (A) is a polycarbonate resin having a structural unit derived from bisphenol A.
[5] The electrostatic discharge according to any one of the above [1] to [4], wherein an injection speed when the polycarbonate resin composition (C) is injection-molded is 100 to 500 mm / second and a cylinder temperature is 240 to 300 ° C. Capacitive touch panel.

  According to the present invention, it is possible to provide a capacitive touch panel that is free from problems of birefringence and poor appearance, can reduce the time required for visual recognition, and can be input with the sense of touch of a finger and has excellent operability.

  Hereinafter, the present invention will be described in detail with reference to embodiments and examples, but the present invention is not limited to the following embodiments and examples and the like, and is within the scope of the present invention. Any change can be made.

[Overview]
The capacitive touch panel of the present invention is a capacitive touch panel having a cover panel having a convex part and / or a concave part that enables the position of the touch sensor to be recognized by a tactile sense, and the cover panel includes a polycarbonate resin ( A) Polycarbonate containing 30 to 230 parts by mass of a styrene resin (B) containing α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic anhydride or a derivative thereof as a copolymerization component with respect to 100 parts by mass The resin composition (C) is formed by injection molding.

Capacitive touch panels include a surface type, a projection type, and the like, both of which detect a position by detecting a change in capacitance between a fingertip and a conductive film.
The surface type is basically composed of three layers of a transparent substrate such as a cover panel, a conductive film, and glass, the conductive film sticks on the transparent substrate, and electrodes are provided at the four corners of the transparent substrate. As a result, a uniform electric field is formed. When a finger touches the screen, a weak current from the driving circuit passes through the corner terminal, conductive film, and cover panel, and forms a closed circuit between the surrounding environment including the ground and the driving circuit via the finger. The position of the finger can be determined by measuring the ratio of the current amounts of the terminals at the four corners on the drive circuit side.
The projection type basically includes a cover panel, an electrode layer below it, and a substrate layer on which a control IC is mounted. In the electrode layer, a large number of mosaic electrode patterns composed of two layers in the vertical and horizontal directions are arranged on a glass or resin substrate by a transparent electrode such as ITO. When the finger touches, the position can be determined accurately by knowing the change in the capacitance of the nearby electrode from the two vertical and horizontal electrode rows. Multiple points can be detected by a large number of electrode rows running vertically and horizontally.

  In the touch panel of the present invention, the cover panel has a convex portion and / or a concave portion that enables the position of the touch sensor to be recognized by a tactile sense. The cover panel is basically a flat plate having a thickness of preferably 0.5 to 8 mm, and the thickness is preferably 1 to 5 mm, more preferably 1.5 to 4 mm. And the convex part or recessed part corresponding to the key position of a touch panel is formed in the surface. As a height or depth of a convex part or a recessed part, it is preferable that it is 0.1-5 mm, for example, More preferably, it is 0.2-3 mm, More preferably, it is 0.5-2 mm.

  In the present invention, as this cover panel, styrene containing α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or a derivative thereof as a copolymer component with respect to 100 parts by mass of the polycarbonate resin (A). A polycarbonate resin composition (C) containing 30 to 230 parts by mass of a resin based resin (B) is used.

[Polycarbonate resin (A)]
There is no restriction on the type of polycarbonate resin (A) used for the production of the cover panel, and one type of polycarbonate resin (A) may be used, or two or more types may be used in combination at any ratio and in any ratio. Also good.

  The polycarbonate resin is a polymer having a basic structure having a carbonic acid bond represented by the formula: — [— O—X—O—C (═O) —] —. In the formula, X is generally a hydrocarbon, but for imparting various properties, X into which a hetero atom or a hetero bond is introduced may be used.

  The polycarbonate resin can be classified into an aromatic polycarbonate resin in which carbon directly bonded to a carbonic acid bond is aromatic carbon and an aliphatic polycarbonate resin in which aliphatic carbon is aliphatic carbon, either of which can be used. Of these, aromatic polycarbonate resins are preferred from the viewpoints of heat resistance, mechanical properties, electrical characteristics, and the like.

  Although there is no restriction | limiting in the specific kind of polycarbonate resin, For example, the polycarbonate polymer formed by making a dihydroxy compound and a carbonate precursor react is mentioned. At this time, in addition to the dihydroxy compound and the carbonate precursor, a polyhydroxy compound or the like may be reacted. Further, a method of reacting carbon dioxide with a cyclic ether using a carbonate precursor may be used. The polycarbonate polymer may be linear or branched. Further, the polycarbonate polymer may be a homopolymer composed of one type of repeating unit or a copolymer having two or more types of repeating units. At this time, the copolymer can be selected from various copolymerization forms such as a random copolymer and a block copolymer. In general, such a polycarbonate polymer is a thermoplastic resin.

A preferred specific example of the polycarbonate resin (A) is 2,2-bis (4-hydroxyphenyl) propane, that is, a polycarbonate resin having a structural unit derived from bisphenol-A.
The polycarbonate resin having a structural unit derived from bisphenol-A may have a carbonate structural unit derived from another dihydroxy compound other than bisphenol-A. The copolymerization amount of structural units other than those derived from bisphenol-A is usually preferably less than 50 mol%, more preferably 40 mol% or less, even more preferably 30 mol% or less, and particularly preferably 20 mol% or less, and 10 mol% or less. Of these, 5 mol% or less is most preferable.

Examples of other dihydroxy compounds include the following aromatic dihydroxy compounds.
Bis (4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxyphenyl) -4-methyl Pentane, 1,1-bis (4-hydroxyphenyl) decane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, bis (4-hydroxy) Phenyl) phenylmethane, 1,1-bis (4-hydroxy-3-cyclohexylphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclooctane, 9,9-bis (4-hydroxyphenyl) fluorene, 4,4′-dihydroxybenzophenone, Examples include 4,4′-dihydroxyphenyl ether, 4,4′-dihydroxybiphenyl, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, and the like.

The viscosity average molecular weight (Mv) of the polycarbonate resin (A) is preferably 16,000 to 28,000. When the viscosity average molecular weight is within this range, a cover panel having good moldability and high mechanical strength can be easily obtained. When the viscosity average molecular weight is less than 16,000, the surface impact resistance is likely to be remarkably lowered, so that it can be used as a cover panel. When it exceeds 28,000, the melt viscosity increases and injection molding tends to be difficult. The lower limit of the molecular weight of the polycarbonate resin (A) is more preferably 17,000, still more preferably 18,000, and the upper limit is more preferably 27,000.
In the present specification, the viscosity average molecular weight (Mv) of the polycarbonate resin is obtained by using dichloromethane as a solvent, using an Ubbelohde viscometer, and determining the intrinsic viscosity ([η]) (unit dl / g) at a temperature of 20 ° C. This means a value calculated from the equation of Schnell's viscosity formula: η = 1.23 × 10 ⁻⁴ M ^0.83 .

  The method for producing the polycarbonate resin (A) is not particularly limited, and any known method can be adopted. Examples thereof include an interfacial polymerization method, a melt transesterification method, a pyridine method, a ring-opening polymerization method of a cyclic carbonate compound, and a solid phase transesterification method of a prepolymer. Among these, the interfacial polymerization method and the melt transesterification method are preferable.

[Styrene resin (B) containing α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or derivative thereof as a copolymerization component]
As the styrenic resin (B) having α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or a derivative thereof as a copolymerization component used in the present invention, a styrene monomer and α, It is a styrene resin copolymerized with β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or a derivative thereof. The form of copolymerization is not limited, and any form such as random copolymerization, block copolymerization, and graft copolymerization may be used.

  Examples of the styrene monomer include alkyl-substituted styrene exemplified by styrene, o-methylstyrene, p-methylstyrene, α-methylstyrene, o-butylstyrene, p-butylstyrene, 2,4-dimethylstyrene, and the like. And halogenated styrene such as chlorostyrene and bromostyrene. Of these, styrene is most preferred.

  The α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or derivative thereof, which is a copolymer component of the styrenic resin, includes (anhydrous) maleic acid and the alkyl or glycol having 1 to 20 carbon atoms. Ester, N-maleimide, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-phenylmaleimide, N-cyclohexylmaleimide, N-methylphenylmaleimide, N-chlorophenylmaleimide and other maleimides, chloro (anhydrous) Examples thereof include maleic acid halides such as maleic acid, (anhydrous) itaconic acid, (anhydrous) citraconic acid and their acid halides, amides, imides, C1-20 alkyl or glycol esters. Here, “(anhydrous)” means α, β-unsaturated dicarboxylic acid anhydride or α, β-unsaturated dicarboxylic acid. Among these, α, β-unsaturated dicarboxylic acid anhydride or α, β-unsaturated dicarboxylic acid is preferable, and α, β-unsaturated dicarboxylic acid anhydride is more preferable.

The combination of the styrene monomer and the copolymerization component of α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or its derivative can be various combinations. Most preferred are styrene and maleic anhydride copolymers in combination with an acid.
As the styrenic resin (B), those produced by a known polymerization method such as bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization can be used. In these polymerization methods, a method in which necessary predetermined components are charged in advance during polymerization may be used, or a method in which predetermined components are sequentially added later may be used. In addition, after the polymerization reaction, a copolymer component that has been amidated or imidized may be used.

  The mass average molecular weight of the styrenic resin (B) is preferably 30,000 to 350,000, more preferably 35,000 to 300,000, and further preferably 40,000 to 270,000. preferable.

  The amount of α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic anhydride or derivative thereof used in the styrene resin (B) is 1 to 35 in 100% by mass of the styrene resin (B). It is preferable that it is mass%, More preferably, it is 2-30 mass%.

[Polycarbonate resin composition (C)]
In the present invention, the content of the styrenic resin (B) containing α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or a derivative thereof as a copolymerization component is 100 masses of the polycarbonate resin (A). 30 to 230 parts by mass with respect to parts. In such a range, the polycarbonate resin composition (C) containing the styrenic resin (B) has improved birefringence, and the cover panel obtained by injection molding of the polycarbonate resin composition (C) is in the step portion of the convex portion (or concave portion). However, birefringence hardly occurs, and an excellent cover panel having a convex portion or a concave portion is obtained.
The preferred content of the styrenic resin (B) is 40 parts by mass or more, more preferably 60 parts by mass or more, still more preferably 70 parts by mass or more, relative to 100 parts by mass of the polycarbonate resin (A). Preferably it is 200 mass parts or less, More preferably, it is 170 mass parts or less, More preferably, it is 150 mass parts or less.

The polycarbonate resin composition (C) contains other resin components in addition to the styrene resin (B) having α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or a derivative thereof as a copolymerization component. You may contain. Preferred examples of the other resin include styrene resins in which α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or derivatives thereof are not copolymerized. As such a styrene resin, a polystyrene resin is preferable. Moreover, you may contain acrylic resin in the range which does not impair the effect of this invention from the point of surface hardness.
When other resins are contained, the content is preferably 70 parts by mass or less, more preferably 60 parts by mass or less, and still more preferably 50 parts by mass or less with respect to 100 parts by mass of the polycarbonate resin (A).

In the polycarbonate resin composition (C), the amount of α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or derivative thereof in the polycarbonate resin composition (C) is 1 to 10% by mass. Preferably there is. By setting the amount of α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or derivative thereof in the polycarbonate resin composition (C) within such a range, the polycarbonate resin (A) and The compatibility of the styrene-based resin (B) is improved, and peeling between the resins and white turbidity can be suppressed. This amount includes the above-mentioned other resins other than the styrene resin (B) having α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or a derivative thereof as a copolymerization component. The same is true for.
The amount of α, β-unsaturated dicarboxylic acid anhydride, α, β-unsaturated dicarboxylic acid anhydride or derivative thereof in the polycarbonate resin composition (C) is more preferably 2% by mass or more, and 3% by mass or more. More preferably, it is 8 mass% or less, and more preferably 6 mass% or less.

[Other ingredients]
The polycarbonate resin composition (C) may contain other components other than those described above as needed, as long as the desired physical properties are not significantly impaired. Examples of other components include resins other than those described above and various resin additives.
Examples of the resin additive include an antioxidant, a heat stabilizer, a release agent, a flame retardant, a flame retardant aid, an ultraviolet absorber, a dye / pigment, an antistatic agent, an antifogging agent, a lubricant, an antiblocking agent, and a fluid. Examples include property improvers, plasticizers, dispersants, and antibacterial agents. In addition, 1 type may contain resin additive and 2 or more types may contain it by arbitrary combinations and a ratio.

[Production Method of Polycarbonate Resin Composition]
There is no restriction | limiting in the manufacturing method of polycarbonate resin composition (C), The manufacturing method of a well-known polycarbonate resin composition can be employ | adopted widely, polycarbonate resin (A), (alpha), (beta)-unsaturated dicarboxylic acid, (alpha), (beta) -unsaturated. After pre-mixing the styrene resin (B) having a dicarboxylic acid anhydride or derivative thereof as a copolymerization component, and other components to be blended as necessary, using various mixers such as a tumbler or a Henschel mixer And a melt kneading method using a mixer such as a Banbury mixer, a roll, a Brabender, a single-screw kneading extruder, a twin-screw kneading extruder, or a kneader.
The temperature for melt kneading is not particularly limited, but is usually in the range of 240 to 320 ° C.

[Cover panel injection molding]
The cover panel of the present invention is manufactured using the polycarbonate resin composition (C) described above. The molding is performed by an injection molding method. For example, the injection molding is performed using a known injection molding machine such as an injection molding machine, an ultra-high speed injection molding machine, or an injection compression molding machine.
The cylinder temperature of the injection molding machine at the time of injection molding is preferably 240 to 340 ° C, and more preferably 260 to 300 ° C. Moreover, the injection speed at the time of injection molding is preferably 60 to 1000 mm / second, more preferably 100 to 500 mm / second, and 150 to 400 mm / second.

  As described above, the cover panel is, for example, a flat plate having a thickness of 0.5 to 8 mm, and the thickness is preferably 1 to 5 mm, more preferably 1.5 to 4 mm. Corresponding convex part or concave part is provided. The concave portion or the convex portion is provided by an uneven portion formed on a part of the surface of the mold during injection molding. As height (or depth) of a convex part (or recessed part), it is 0.1-5 mm, More preferably, it is 0.2-3 mm, More preferably, it is 0.5-2 mm, but above-mentioned polycarbonate resin composition By using the object (C), a cover panel having such a step can be injection molded without problems of birefringence and poor appearance. In addition, the height (or depth) of said convex part (or recessed part) means the longest height (or depth) of a height (or depth) direction.

There is no limitation in particular in the shape of the convex part or recessed part provided on the surface of a cover panel. As the convex part or concave part shape in the cover panel thickness direction in the convex part or concave part, for example, a substantially semi-circular shape, a substantially semi-elliptical shape, a substantially semi-oval shape, a substantially triangular shape, a substantially rectangular shape, a substantially square shape, an arc shape, a tapered shape, The shape etc. which combined taper shape and circular arc shape are mentioned. As the shape in the plane direction perpendicular to the cover panel thickness direction in the convex portion or the concave portion, for example, a substantially circular shape, a semi-circular shape, a substantially elliptical shape, a substantially semi-elliptical shape, a substantially oval shape, a substantially semi-oval shape, a substantially triangular shape, Examples include a substantially rectangular shape and a substantially square shape.
The area of one convex portion or concave portion is preferably 1～400Mm ^2, more preferably 25～350Mm ^2, more preferably a 50 to 300 mm ^2. By making the shape and area of the convex portion or concave portion as described above, it is preferable that the key position is easily recognized when the cover panel surface is touched by hand.

[Capacitive touch panel]
As described above, the cover panel obtained above is assembled together with the electrode layer, the substrate layer on which the control IC is mounted, and the like, and has electrostatic and convex portions and / or concave portions that can recognize the position of the touch sensor by touch. It becomes a capacitive touch panel.
The capacitive touch panel of the present invention is suitable for various tablet-type mobile terminals such as smart phones, tablet-type personal computers, car navigation systems, car audio systems, and the like, and can be operated while reducing the time required for visual recognition. It is particularly suitable for automobiles and for visually impaired people.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples, and can be arbitrarily modified and implemented without departing from the gist of the present invention.
Each raw material component used in the following Examples and Comparative Examples is as shown in Table 1 below.

(Examples 1-4, Comparative Example 1)
Each component described in Table 1 above was blended in the proportions shown in Table 2 below (all expressed in parts by mass) and mixed uniformly with a tumbler mixer, and then a twin screw extruder (TEX30HSST manufactured by Nippon Steel Works). ) Was fed to the extruder from the barrel upstream of the extruder at a cylinder temperature of 260 ° C., a screw speed of 200 rpm, and a discharge rate of 20 kg / hr, and melt-kneaded to obtain a pellet of a polycarbonate resin composition.

[Flow value (Q value, unit: x 0.01 cc / sec)]
After drying the pellets obtained by the above production method at 100 ° C. for 5 hours, the amount of effluent per unit time (Q value, 280 ° C., load 160 kgf) using an elevated flow tester (Unit: x 0.01 cc / sec) was measured to evaluate the fluidity. An orifice having a diameter of 1 mm and a length of 10 mm was used.

[Molding of average retardation measurement specimen]
The pellets obtained by the above production method are dried at 100 ° C. for 5 hours, and then an injection molding machine (“J55-60H” manufactured by Nippon Steel Works) is used. The cylinder set temperature is 280 ° C., the mold temperature is 80 ° C., and the injection speed is 200 mm. / Sec, injection molding under the conditions of a molding cycle of 40 seconds, and a flat test piece (90 mm × 60 mm × thickness 2 mm) for measuring an average retardation and a thickness of 90 mm × 50 mm for measuring an average retardation of a step portion. Two-stage plates of 2 mm and 3 mm were injection molded.

[Measurement of average retardation (unit: nm)]
For measuring the average retardation obtained by the above method by three-wavelength measurement (wavelength: 523, 543, 575 nm) using a wide-range two-dimensional birefringence evaluation system (Photonic Lattice, model: WPA-100) The phase difference of the flat gate test piece (90 mm × 60 mm × thickness 2 mm) in the 45 mm × 60 mm square anti-gate portion was subjected to area analysis, and the average value (unit: nm) was obtained.

[Measurement of average retardation of step (unit: nm)]
Thicknesses of 2 mm and 3 mm obtained by the above method by three-wavelength measurement (wavelength 523, 543, 575 nm) using a wide-range two-dimensional birefringence evaluation system (Photonic Lattice, model: WPA-100) The phase difference in a 10 mm × 10 mm square region of 2 mm thick part from the center of the boundary line between the 2 mm thick part and 3 mm thick part of the corrugated plate was subjected to area analysis, and the average value (unit: nm) was obtained.

[Transparency evaluation (total light transmittance) (unit:%)]
After the pellets obtained by the above production method were dried at 100 ° C. for 5 hours, a cylinder temperature of 280 ° C., a mold temperature of 80 ° C., and a molding cycle of 35 seconds were used using a NEX80 injection molding machine manufactured by Nissei Plastic Industries. , Injection molding under the conditions of an injection speed of 200 mm / second, a flat test piece (90 mm × 50 mm × 3 mm thickness) was formed, and an NDH-2000 type haze meter manufactured by Nippon Denshoku Industries Co., Ltd. according to JIS K 7105 The total light transmittance (unit:%) was measured.

[Visibility of touch panel]
The two-step plate having step portions having a thickness of 2 mm and 3 mm obtained by the above method was placed on the touch panel of the smartphone so that the step portion became the center of the screen. The visibility of characters displayed on the screen was evaluated from a distance of 50 cm above the touch panel on which the two-stage plate was placed, with the polarizing plate in a parallel Nicol state approaching the eyes.
Of the 23 rows and 14 columns of characters (322) displayed in the center 90mm x 40mm of the screen, those that are clearly visible in 90% or more are "A", and those that are 75% or more and less than 90% are clearly visible. “B” was determined as “B”, “C” when 60% or more and less than 75% could be clearly seen, and “D” when less than 60% was clearly visible.
The above evaluation results are shown in Table 2 below.

  The capacitive touch panel of the present invention has no problem of birefringence or poor appearance, can reduce the time required for visual recognition, and is an excellent capacitive operability that can be input by touching a finger. It is suitable for various tablet-type portable terminals, tablet-type personal computers, car navigation systems, car audio systems, and the like, and has high industrial applicability.

Claims (5)

  A capacitive touch panel having a cover panel having a convex part and / or a concave part that enables a touch sensor to recognize the position of the touch sensor, wherein the cover panel is α, with respect to 100 parts by mass of the polycarbonate resin (A). Injection molding of a polycarbonate resin composition (C) containing 30 to 230 parts by mass of a styrene resin (B) having a copolymer component of β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or a derivative thereof. Capacitive touch panel characterized by being made.   2. The electrostatic according to claim 1, wherein the amount of α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or derivative thereof in the polycarbonate resin composition (C) is 1 to 10% by mass. Capacitive touch panel.   The amount of α, β-unsaturated dicarboxylic acid, α, β-unsaturated dicarboxylic acid anhydride or derivative thereof in the styrenic resin (B) is 1 to 35% by mass. Capacitive touch panel.   The capacitive touch panel according to any one of claims 1 to 3, wherein the polycarbonate resin (A) is a polycarbonate resin having a structural unit derived from bisphenol A.   The capacitive touch panel according to any one of claims 1 to 4, wherein an injection speed when the polycarbonate resin composition (C) is injection-molded is 100 to 500 mm / second, and a cylinder temperature is 240 to 300 ° C.