JP5463972B2 - Hard coat substrate for touch panel and touch panel using the same - Google Patents

Description

  The present invention relates to a hard coat substrate for a touch panel used for a resistive touch panel and the like, and more specifically, the generation of interference fringes is suppressed when the touch panel is pressed, and the transparency and visibility are excellent. The present invention relates to a hard coat substrate for a touch panel.

  The present invention relates to a hard coat substrate for a touch panel used for a resistive touch panel and the like, and more specifically, the generation of interference fringes is suppressed when the touch panel is pressed, and the transparency and visibility are excellent. The present invention relates to a hard coat substrate for a touch panel.

  2. Description of the Related Art In recent years, touch panels that are arranged on a display device such as a CRT or an LCD and can input data, instructions, and commands by pressing with a finger or a pen while watching the display have become widespread. The touch panel is classified into various methods such as a capacitance type based on its position detection principle, but a method called a resistance film type is mainly used because of its ease of mass production.

  The structure of a conventional resistive film type touch panel is shown in FIG. The upper substrate (1) comprises an insulating transparent upper substrate (11), a transparent conductive sheet comprising a hard coat layer (12) on one side and a transparent conductive film (13) on the other side. The lower substrate (2) is composed of a transparent conductive sheet composed of an insulating transparent lower substrate (21) and a transparent conductive film (22). Both base materials are arranged to face each other via an insulating spacer (3) to constitute a transparent touch switch. By pressing the touch panel configured in this way with a touch pen or a finger, the electrode surfaces come into contact with each other and are electrically connected, and position detection is performed from a change in the electrical resistance value.

  A transparent plastic such as polyethylene terephthalate is used for the upper substrate and the lower substrate, and a thin film of metal oxide such as a composite oxide of indium and tin (ITO) is used as the transparent conductive film. .

  Since the touch panel is disposed on the display device, high transparency is required. In addition, since the input surface is pressed by a plastic input pen resembling the shape of a ballpoint pen or the like, a finger with extended nails, etc., scratch resistance and high surface hardness (3H or more as measured by JIS-K5600-5-4) ) Is required. In general, sufficient transparency and hardness can be obtained by using an ultraviolet curable resin such as acrylate as the material of the hard coat.

  In such a resistive film type touch panel, when the touch panel is pressed, the distance between the upper base material and the lower base material becomes narrower continuously toward the point where the press is made. At this time, the surface reflection light of the upper base material and the surface reflection light of the lower base material interfere with each other, and interference fringes (Newton rings) are generated around the pressed point, and there is a problem that visibility is remarkably lowered. .

  As a method of suppressing such interference fringes, for example, as in Patent Document 1, Patent Document 2, or Patent Document 3, an interference-proof layer having a surface that is uneven using a filler such as silica particles is placed under the transparent conductive film. A method using a provided base material is known. A cross-sectional view thereof is shown in FIG. As shown in FIG. 2, the anti-interference base material (4) includes a substrate (41), an anti-interference layer (42) having particles (421) and a resin (422) on the substrate and having an uneven shape, and an anti-interference It consists of a transparent conductive film (43) provided on the layer surface. By using such a base material for either or both of the upper part and the lower part, it is possible to scatter light at the uneven part of the base material and suppress interference fringes.

JP 2004-151937 A JP 2005-262597 A JP 11-296303 A

  However, if this uneven shape is too small, the interference fringes are not suppressed, and if it is too large, the interference fringes can be suppressed, but the haze value (haze value) of the film surface increases, and the transmission sharpness decreases accordingly. there were. Furthermore, the unevenness of the surface becomes uneven due to the aggregation and dispersion of the particles used, and there is a problem that a bright spot called scintillation is generated and the visibility of the display screen is lowered, and interference fringe suppression ability In addition, a base material for a touch panel having high levels of transparency and visibility has not been obtained.

  An object of this invention is to provide the hard-coat base material for touchscreens in which generation | occurrence | production of the interference fringe was suppressed in view of said problem, and was excellent in transparency and visibility.

  Therefore, as a result of intensive studies in view of the above-mentioned problems, the present inventor performed uneven processing on the film surface using two types of particles having a difference in refractive index with respect to the anti-interference layer within 0.05 and having different particle sizes. By applying, it was found that aggregation and localization of the particles were suppressed to form a favorable concavo-convex shape, and high interference fringe suppressing ability, transparency and visibility were obtained, and the present invention was achieved.

That is, in the invention according to claim 1, the front surface of the film is the first surface, the back surface is the second surface, the hard coating layer is formed on the first surface of the film, and the particles A, B and resin are formed on the second surface. In the hard coat film in which the interference preventing layer and the transparent conductive layer are laminated, the average film thickness of the interference preventing layer is 2.0 μm or more and 5.0 μm or less, and the refractive index of the particles A and the refractive index of the resin The difference is 0.05 or less, the difference between the refractive index of the particle B and the refractive index of the resin is 0.05 or less, and the average particle diameter of the particle A is divided by the average film thickness of the anti-interference layer. The value obtained by dividing the average particle diameter of the particles B by the average film thickness of the anti-interference layer is 0.1 or more and 0.3 or less . The average particle diameter is larger than the average particle diameter of the particles B , and the height of the protrusions on the surface of the transparent conductive layer is An average distance between protrusions of 0.3 μm or more is 20 μm or more and 100 μm or less, and the maximum height of the protrusions is 0.5 μm or more and 5 μm or less.

  The invention according to claim 2 is the hard coat substrate for a touch panel according to claim 1, wherein either one or both of the particles A and the particles B are subjected to a surface treatment.

  The invention according to claim 3 is the hard coat substrate for a touch panel according to claim 1 or 2, wherein the total light transmittance is 90% or more and the haze is 3% or less. .

  Moreover, as invention which concerns on Claim 4, it is a touch panel using the hard-coat base material for touch panels in any one of Claim 1 to 3.

  By setting it as the hard-coat film for touchscreens of the said structure, generation | occurrence | production of an interference fringe is suppressed and the hardcoat base material for touchscreens excellent in the permeability | transmittance and visibility can be obtained.

It is sectional drawing of a general resistive film type touch panel. It is a cross-sectional view of a conventional interference-proof substrate. It is sectional drawing of the hard-coat base material for touchscreens of this invention.

Hereinafter, the hard-coat base material for touchscreens of this invention is demonstrated using FIG.
The cross-sectional schematic diagram of the hard-coat base material for touchscreens of this invention was shown in FIG. The hard-coat base material (5) for touchscreens of this invention has a hard-coat layer (52) on one side of a transparent resin substrate (51), and an interference prevention layer (53) and a transparent conductive layer ( 54). The anti-interference layer (53) includes a resin (530), particles A (53A), and particles B (53B).

  The particle A is mainly used for forming a surface irregular shape, and the particle B is used for improving the dispersion of the particle A and forming a fine irregular shape on the surface. By adding the particles B, the probability that the particles A come into contact with each other can be reduced, and as a result, aggregation of the particles A can be suppressed. Further, when the particle B having a small particle diameter is added to the interference prevention layer, finer irregularities are formed and the interference fringe suppression ability is improved. By these effects, high interference fringe suppression ability can be realized without reducing transparency and visibility.

  In the present invention, the difference between the refractive index of the particle A and the refractive index of the resin is 0.05 or less, and the difference between the refractive index of the particle B and the refractive index of the resin is 0.05 or less. It is preferable. If the difference in refractive index exceeds 0.05, the internal haze in the interference-preventing layer increases, and transparency and visibility are deteriorated.

  Moreover, it is preferable that the value which remove | divided the average particle diameter of the said particle | grains A by the average film thickness of the said interference prevention layer is 0.5 or more and 0.8 or less. When the value obtained by dividing the average particle diameter of the particles A by the average film thickness of the interference preventing layer is smaller than 0.5, the formed irregularities are not so large and sufficient interference fringe suppression ability cannot be obtained. On the other hand, when the value obtained by dividing the average particle diameter of the particles A by the average film thickness of the anti-interference layer is larger than 0.8, the optical characteristics of the anti-interference layer to be formed is It changes sharply, and the probability of appearance defects and the like significantly increases.

  Moreover, it is preferable that the value which remove | divided the average particle diameter of the said particle | grains B by the average film thickness of the said interference prevention layer is 0.1 or more and 0.3 or less. When the value obtained by dividing the average particle diameter of the particles B by the average film thickness of the interference preventing layer is smaller than 0.1, the effect of adding the particles is not obtained because the particles are too small. On the other hand, when larger than 0.3, aggregation of the particles A cannot be prevented.

  In the present invention, the average distance between protrusions having a height of 0.3 μm or more is preferably 20 μm or more and 100 μm or less, and the maximum height of the protrusions is preferably 0.5 μm or more and 5 μm or less. Here, the protrusion means a convex shape on the surface of the transparent conductive layer formed by the particles A and the particles B included in the interference preventing layer. When the average distance between protrusions having a height of 0.3 μm or more is less than 10 μm, the transmittance of the film is lowered, so that the visibility is lowered. On the other hand, when it exceeds 100 μm, the interference fringe suppressing ability cannot be obtained. On the other hand, when the maximum height of the protrusion exceeds 5 μm, the texture becomes rough and the visibility becomes low. On the other hand, when it is less than 0.5 μm, the interference fringe suppressing ability cannot be obtained.

  Regarding the average distance of the protrusions, when the roughness curve (JIS-B-0601) of the rough surface obtained with a stylus roughness meter or the like is measured length L and the number of protrusions exceeding a predetermined height is N , L / N. In addition, the maximum height of the rough surface is measured based on JIS-B-0601.

  In the present invention, either or both of the particles A and the particles B are preferably subjected to a surface treatment such as a hydrophobic treatment. Thereby, aggregation of particles can be prevented.

  Then, the manufacturing method of this invention is demonstrated.

  The transparent resin substrate used in the present invention is not particularly limited, and can be appropriately selected from known plastic films. Specifically, polyethylene film, polypropylene film, polyester film, polyvinyl chloride film, cellophane, nylon film, polyvinyl alcohol film, polycarbonate film, polyvinylidene chloride film, polyacetate film, polystyrene film, acrylic film, heat resistance -Plastic films such as engineering plastic films, fluororesin films, and triacetyl cellulose films.

  Although the thickness of the said transparent resin base material is not specifically limited, Preferably they are 50 micrometers or more and 500 micrometers or less, More preferably, they are 100 micrometers or more and 400 micrometers or less.

  The main component of the hard coat agent used when forming the hard coat layer and the interference prevention layer of the present invention is preferably an acrylate from the viewpoint of transparency and surface hardness. Although not particularly limited, a resin that can withstand the temperature during transparent conductive layer lamination and maintain transparency is preferable. In addition to the mechanical properties and transparency after curing, chemical resistance, and heat resistance, as well as various physical properties such as low viscosity during coating processing, specifically, more than three functionalities that can be expected to achieve three-dimensional crosslinking An ultraviolet curable resin obtained by crosslinking a monomer or oligomer mainly composed of acrylate may be used. Examples of the trifunctional or higher acrylate include trimethylolpropane triacrylate, isocyanuric acid EO-modified triacrylate, and the like. These may be used alone or in combination of two or more. These resins are preferably those that can be cured within 5 minutes in consideration of industrial production regardless of which coating method is used.

  Examples of the base curable resin include compounds having at least one crosslinkable double bond in one molecule. For example, the photocurable resin is preferably an acrylic resin such as polyurethane acrylate, epoxy acrylate, or polyol acrylate. Specifically, it contains a crosslinkable oligomer, a monofunctional or polyfunctional monomer, a photopolymerization initiator, a photoinitiator auxiliary agent, and the like.

  As the crosslinkable oligomer, acrylic oligomers such as polyester (meth) acrylate, polyether (meth) acrylate, polyurethane (meth) acrylate, epoxy (meth) acrylate, and silicone (meth) acrylate are preferable. Specific examples include polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, bisphenol A type epoxy acrylate, polyurethane diacrylate, cresol novolac type epoxy (meth) acrylate, and the like.

  As the monofunctional or polyfunctional monomer, acrylic monomers such as (meth) acrylic acid esters are preferable. Specific examples of the bifunctional (meth) acrylic acid ester include tripropylene glycol di (meth) acrylate, 1,6-hexanediol diacrylate, and tetraethylene glycol di (meth) acrylate. Examples of the trifunctional (meth) acrylic acid ester include trimethylolpropane tri (meth) acrylate and pentaerythritol tri (meth) acrylate. Examples of tetrafunctional (meth) acrylic acid esters include tetramethylolmethane tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate. Examples of hexafunctional (meth) acrylic acid esters include dipentaerythritol hexaacrylate.

  In addition, the average film thickness of the anti-interference layer is 2.0 μm or more and 5.0 μm or less in consideration of the curl strength of the hard coat layer on the opposite surface through the transparent resin substrate, the particle size of the particles used, etc. It is preferable to do.

  In the present invention, when the active energy ray is ultraviolet light, it is necessary to add a photosensitizer (photopolymerization initiator), and benzoin, benzoin methyl ether, benzoin ethyl ether are used as radical-generating photopolymerization initiators. Benzoins such as benzoin isopropyl ether and benzyl methyl ketal and their alkyl ethers; acetophenones such as acetophenone, 2,2, -dimethoxy-2-phenylacetophenone and 1-hydroxycyclohexyl phenyl ketone; methyl anthraquinone and 2-ethylanthraquinone Anthraquinones such as 2-amylanthraquinone; thioxanthones such as thioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; acetophenone dimethyl ketal; Ketals such as emissions Jill dimethyl ketal; benzophenone, and the like 4,4-bis benzophenones such as methylamino benzophenone and azo compounds. These can be used alone or as a mixture of two or more thereof, and further, tertiary amines such as triethanolamine and methyldiethanolamine; benzoic acid derivatives such as 2-dimethylaminoethylbenzoic acid and ethyl 4-dimethylaminobenzoate, etc. It can be used in combination with a photoinitiator aid or the like.

  The addition amount of the photopolymerization initiator is 0.1 to 5 parts by weight, preferably 0.5 to 3 parts by weight with respect to the main component acrylate. Less than the lower limit is not preferable because the hard coat layer is insufficiently cured. Moreover, when exceeding an upper limit, since yellowing of a hard-coat layer arises or a weather resistance falls, it is unpreferable.

  The light used for curing the photocurable resin is ultraviolet rays, electron beams, or gamma rays, and in the case of electron beams or gamma rays, it is not always necessary to contain a photopolymerization initiator or a photoinitiating aid. As these radiation sources, high pressure mercury lamps, xenon lamps, metal halide lamps, accelerated electrons, and the like can be used.

  The solvent is not particularly limited as long as it dissolves the main component acrylate. Specifically, ethanol, isopropyl alcohol, isobutyl alcohol, benzene, toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, n-butyl acetate, isoamyl acetate, ethyl lactate, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl Examples include cellosolve acetate and propylene glycol monomethyl ether acetate. These solvents may be used alone or in combination of two or more.

  The particles used in the present invention include organic particles such as acrylic resin, polystyrene resin, polyester resin, polyolefin resin, polyamide resin, polycarbonate resin, polyurethane resin, silica, talc, various aluminosilicates, kaolin clay, MgAl hydrotalcite, etc. It is appropriately selected that the difference between the inorganic particles and the refractive index of the resin of the interference prevention layer to be used is within 0.05. These may be copolymers obtained by copolymerizing two or more types of monomers. Further, as described above, it is desirable to use particles A and particles B whose surfaces have been subjected to a surface treatment such as a hydrophobic treatment.

  The coating method on the film substrate is not particularly limited, but practically a die coater, curtain flow coater, roll coater, reverse roll coater, gravure coater, knife coater, bar coater, spin coater, micro Coating with a gravure coater or the like is common.

  As a general method for forming the transparent conductive layer, there are a PVD method such as a sputtering method, a vacuum deposition method, and an ion plating method, a CVD method, a coating method, a printing method, and the like. The material for forming the transparent conductive layer is not particularly limited, and examples thereof include indium-tin composite oxide (ITO), tin oxide, copper, aluminum, nickel, and chromium. May be formed. In order to improve adhesion, a metal layer made of a single metal element or an alloy of two or more metal elements may be provided between the undercoat layer and the base film. It is desirable to use a metal selected from the group consisting of silicon, titanium, tin and zinc for the metal layer.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[Example 1]
(1) Application of hard coat layer The following coating liquid for hard coat layer is applied to one surface of a polyethylene terephthalate (PET) film (manufactured by Teijin Ltd., 125 μm thick) with a wire bar, dried, and then irradiated with ultraviolet light using a high-pressure mercury lamp. A hard coat layer having a thickness of 5 μm was formed by irradiation. Subsequently, the other surface was coated with an anti-interference layer coating solution of the following formulation with a wire bar and dried, and an anti-interference layer having a thickness of 5 μm was formed by ultraviolet irradiation with a high-pressure mercury lamp to prepare a hard coat film.

<Coating liquid for hard coat layer>
Ionizing radiation curable resin (acrylic resin)
(Purple light UV-7605B: Nippon Synthetic Chemical Co., Ltd .: refractive index 1.49) 49 parts by weight Photopolymerization initiator (Irgacure 184: Ciba Specialty Chemicals) 2 parts by weight Methyl acetate 49 parts by weight

<Coating solution for interference prevention layer>
Ionizing radiation curable resin (acrylic resin)
(Violet UV-7605B: Nippon Synthetic Chemical Co., Ltd .: Refractive index 1.49) 39 parts by weight Photopolymerization initiator (Irgacure 184: Ciba Specialty Chemicals Co., Ltd.) 2 parts by weight Acrylic resin (MX-350: Soken Chemical Co., Ltd .: Particle size 3 0.5 μm: Refractive index 1.49) 10 parts by weight Silica particles (SS50F: Tosoh Silica Industry: Particle size 1.1 μm: Refractive index 1.44) 10 parts by weight Methyl acetate 39 parts by weight

(2) ITO film formation A 20 nm thick ITO conductive film was formed by sputtering on the surface of the hard coat film on the anti-interference layer to produce a hard coat substrate for a touch panel of the present invention.

[Comparative Example 1]
In Example 1, the silica particles used in the anti-interference layer were the same as in Example 1 except that 10 parts by weight of styrene resin (SX-350H: Soken Chemical Co., Ltd .: particle size 3.5 μm: refractive index 1.59) was used. The hard-coat base material for touchscreens of the comparative example 1 was produced.

[Comparative Example 2]
In Example 1, the same procedure as in Example 1 was used except that the particles used for the anti-interference layer were 20 parts by weight of acrylic resin (MX-350: Soken Chemical Co., Ltd .: particle size 3.5 μm: refractive index 1.49). A hard coat substrate for a touch panel of Comparative Example 2 was produced.

[Comparative Example 3]
In Example 1, the particles used for the anti-interference layer were the same as in Example 1 except that only 20 parts by weight of silica particles (SS50F: Tosoh Silica Industry: particle size 1.1 μm: refractive index 1.44) were compared. The hard coat substrate for touch panel of Example 3 was produced.

[Comparative Example 4]
In Example 1, the hard-coat base material for touchscreens of the comparative example 4 was produced like Example 1 except not containing particle | grains in an interference prevention layer.

  Using the hard coat films obtained in Examples and Comparative Examples, interference fringe prevention ability, transparency, visibility, and surface roughness were evaluated. The evaluation results are shown in Table 1.

(1) Interference fringe suppression ability Two hard coat films of Examples and Comparative Examples were used, the interference-proof layer surfaces were brought into close contact with each other and pressurized at 1 kg / 25 cm ² , and no interference fringes were generated. The resulting product was designated as “x”.

(2) Transparency The haze of the hard coat films of Examples and Comparative Examples was measured using a haze meter (NDH2000: Nippon Denshoku Co., Ltd.) based on JIS-K7136: 1997, and the measured value was 3.0%. What was less than "○" was assigned, and what was 3.0% or more was assigned "X". In the measurement, light was incident from the surface having the conductive layer.

  Moreover, the total light transmittance of the hard coat film of an Example and a comparative example is measured using a haze meter (NDH2000: Nippon Denshoku Co., Ltd.) based on JIS-K7361: 2000, and a measured value is 90% or more. What was there was “◯”, and what was less than 90% was “x”. In the measurement, light was incident from the surface having the conductive layer.

(3) Visibility About the hard coat film of the example and the comparative example, based on JIS-K7105, using an image clarity measuring device (ICM-1DP: Suga Test Instruments Co., Ltd.), an optical comb image clarity of 2.0 mm is obtained. The measurement value was 90% or more, and “◯” was given, and the measurement value was less than 90% was taken as “X”. In the measurement, light was incident from the surface having the hard coat layer.

  Also, the display screen of the CRT display is displayed in 100% green, and the hard coat surfaces of the hard coat films of the examples and comparative examples are brought into close contact with the display screen. "X" was used.

(4) Surface roughness The distance between the protrusions on the rough surface was calculated by obtaining a roughness curve using a surface roughness meter (Kosaka Laboratory SE30K) based on JIS-B-0601. The maximum height of the rough surface was measured using the same surface roughness meter based on JIS-B-0601.

  As is clear from Table 1, the hard coat substrate for touch panel of Example 1 had sufficient interference fringe suppressing ability, transparency, and visibility, with sufficient irregularities formed in the anti-interference layer.

  Since the hard coat film of Comparative Example 1 used styrene particles having a refractive index difference of 0.10 between the particles A and the anti-interference layer, the image sharpness was low.

  Since the hard coat film of Comparative Example 2 did not contain silica particles having a small particle size, the dispersion of acrylic particles was poor and the interference fringe prevention ability was high, but there were problems with transparency and visibility.

  Since the hard coat film of Comparative Example 3 used only silica particles having a small particle size, sufficient irregularities were not formed and the interference fringe preventing ability was not exhibited.

  The hard coat film of Comparative Example 4 did not have irregularities and did not exhibit interference fringe suppression ability.

  The hard coat substrate of the present invention is used as an upper substrate or a lower substrate for a touch panel.

DESCRIPTION OF SYMBOLS 1 Upper base material 11 Upper substrate 12 Hard coat layer 13 Transparent conductive film 2 Lower electrode 21 Lower substrate 22 Transparent conductive film 3 Insulating spacer 4 Interference-proof base material 41 Substrate 42 Anti-interference layer 421 Particle 422 Resin 43 Transparent conductive film 5 Touch panel Hard coat substrate 51 Transparent resin substrate 52 Hard coat layer 53 Anti-interference layer 531 Hard coat resin 53A Particle A
53B Particle B
54 Transparent conductive layer

Claims (4)

The film surface was the first surface, the back surface was the second surface, a hard coat layer was laminated on the first surface of the film, and an anti-interference layer having particles A, particles B and a resin and a transparent conductive layer were laminated on the second surface. In hard coat film,
The average film thickness of the anti-interference layer is 2.0 μm or more and 5.0 μm or less,
The difference between the refractive index of the particle A and the refractive index of the resin is 0.05 or less,
The difference between the refractive index of the particle B and the refractive index of the resin is 0.05 or less,
A value obtained by dividing the average particle diameter of the particles A by the average film thickness of the interference preventing layer is 0.5 or more and 0.8 or less,
The value obtained by dividing the average particle diameter of the particles B by the average film thickness of the anti-interference layer is 0.1 or more and 0.3 or less,
The average particle size of the particles A is larger than the average particle size of the particles B,
Of the protrusions on the surface of the transparent conductive layer, the average distance between protrusions having a height of 0.3 μm or more is 20 μm or more and 100 μm or less,
The hard coat substrate for a touch panel, wherein the maximum height of the protrusion is 0.5 μm or more and 5 μm or less.   The hard coat substrate for a touch panel according to claim 1, wherein one or both of the particles A and the particles B are subjected to a surface treatment.   The hard coat substrate for a touch panel according to claim 1 or 2, wherein the total light transmittance is 90% or more and the haze is 3% or less.   The touch panel using the hard-coat base material for touchscreens in any one of Claim 1 to 3.

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