JP2013076017A - Adhesive composition for touch panel, adhesion type optical film for touch panel, optical member for touch panel, and touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED To provide an acrylic pressure-sensitive adhesive composition or a pressure-sensitive adhesive layer containing an acrylic pressure-sensitive adhesive composition and a dye in addition to achieving color display properties and high total light transmittance which have been difficult to achieve in the past. An object of the present invention is to provide a pressure-sensitive adhesive composition for a touch panel, a pressure-sensitive adhesive optical film for a touch panel, an optical member for a touch panel, and a touch panel that are less likely to deteriorate with time.
The present invention is a pressure-sensitive adhesive composition for a touch panel containing an acrylic pressure-sensitive adhesive and a porphyrin compound.
[Selection] Figure 1

Description

  The present invention relates to a pressure-sensitive adhesive composition for a touch panel excellent in color display properties and total light transmittance, a pressure-sensitive adhesive optical film for a touch panel, an optical member for a touch panel, and a touch panel.

  The touch panel is used on the front surface of a display such as a portable terminal, a portable game machine, and various fixed terminals. In recent years, environmentally conscious product development has been actively carried out, but there is an increasing interest in aiming at energy saving also in the touch panel or members constituting the touch panel. Increasing the total light transmittance can be cited as one that contributes to energy saving in the optical member used in the touch panel. Examples of the method for increasing the total light transmittance include a method of forming an antireflection layer on the back surface (display side) of the optical member. The antireflection layer utilizes the principle of optical interference, and is formed by alternately forming one or more high refractive index films and a thin low refractive index film, and disposing the thin low refractive index film on the observation surface side. is there. It is known that by forming the antireflection layer, the total light transmittance is improved by about several percent, depending on the type of the optical member.

There are various touch panel methods. For example, there are a resistive film method that specifies the input position by contacting the upper and lower electrodes, and a capacitance method that specifies the input position from the change in capacitance. A transparent conductive film is used for the method. Since this transparent conductive film is required to be transparent and conductive, indium tin oxide (ITO) is often used (for example, see Patent Document 1).

JP 2003-151358 A

However, since indium tin oxide used as a transparent conductive film exhibits a yellow color, the color display properties of the touch panel are impaired.
In order to solve this problem, the color display problem can be solved by laminating a blue layer on the transparent conductive film. However, when a general-purpose dye is used, a problem arises in that although the color display property is improved, the total light transmittance is lowered. That is, achieving both color display properties and high total light transmittance is in a trade-off relationship.
In addition, when a pressure-sensitive adhesive layer containing an acrylic pressure-sensitive adhesive composition is used as a blue color layer, there is a problem that a blue colorant deteriorates with time.

  Therefore, the present invention achieves color display properties and high total light transmittance that have been difficult to achieve in the past, and further contains a dye in the acrylic pressure-sensitive adhesive composition or the pressure-sensitive adhesive layer containing the acrylic pressure-sensitive adhesive composition. An object of the present invention is to provide a pressure-sensitive adhesive composition for a touch panel, a pressure-sensitive adhesive optical film for a touch panel, an optical member for a touch panel, and a touch panel that are less likely to deteriorate with time even if the dye is used.

The present invention has solved the above problems by the following technical configuration.

（式中、Ａ^１〜Ａ^８はそれぞれ独立に、水素原子、ハロゲン原子、ニトロ基、シアノ基、ヒドロキシ基、スルホン酸基、炭素数１〜２０のアルキル基、ハロゲノアルキル基、アルコキシ基、アルコキシアルコキシ基、アリールオキシ基、モノアルキルアミノ基、ジアルキルアミノ基、アラルキル基、アリール基、ヘテロアリール基、アルキルチオ基、又はアリールチオ基を表し、Ａ^１とＡ^２、Ａ^３とＡ^４、Ａ^５とＡ^６、Ａ^７とＡ^８はそれぞれ独立に、連結基を介して芳香族環を除く環を形成しても良く、Ｍは２個の水素原子、２価の金属原子、３価の１置換金属原子、４価の２置換金属原子、又はオキシ金属原子を表す。）
（３） 前記アクリル系粘着剤１００質量部に対して、前記ポルフィリン化合物を０.０００１質量部以上配合したことを特徴とする前記（１）記載のタッチパネル用粘着剤組成物。
（４） 透光性基体上に、直接または他の層を介して、前記（１）〜（３）のいずれか一項に記載のタッチパネル用粘着剤組成物を積層したことを特徴とするタッチパネル用粘着型光学フィルムである。
（５）透明導電膜上に、直接または他の層を介して、前記（１）〜（３）のいずれか一項に記載のタッチパネル用粘着剤組成物を積層したことを特徴とするタッチパネル用光学部材である。
（６）前記（４）に記載のタッチパネル用粘着型光学フィルムまたは前記（５）に記載のタッチパネル用光学部材を備えたことを特徴とするタッチパネルである。 (1) A pressure-sensitive adhesive composition for a touch panel containing an acrylic pressure-sensitive adhesive and a porphyrin compound.
(2) The pressure-sensitive adhesive composition for touch panel as described in (1) above, wherein the porphyrin compound is represented by the following general formula (1).

(In the formula, A ^{1 to} A ⁸ are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfonic acid group, an alkyl group having 1 to 20 carbon atoms, a halogenoalkyl group, an alkoxy group, an alkoxy group. Represents an alkoxy group, an aryloxy group, a monoalkylamino group, a dialkylamino group, an aralkyl group, an aryl group, a heteroaryl group, an alkylthio group, or an arylthio group, and A ¹ and A ² , A ³ and A ⁴ , A ⁵ and A ⁶ , A ⁷ and A ⁸ may each independently form a ring excluding an aromatic ring via a linking group, and M is two hydrogen atoms, a divalent metal atom, a trivalent mono-substitution Represents a metal atom, a tetravalent disubstituted metal atom, or an oxymetal atom.)
(3) The pressure-sensitive adhesive composition for a touch panel according to (1), wherein 0.0001 parts by mass or more of the porphyrin compound is blended with respect to 100 parts by mass of the acrylic pressure-sensitive adhesive.
(4) A touch panel in which the pressure-sensitive adhesive composition for a touch panel according to any one of (1) to (3) is laminated on a light-transmitting substrate directly or via another layer. It is a pressure-sensitive adhesive optical film.
(5) The touch panel pressure-sensitive adhesive composition according to any one of (1) to (3) above is laminated on the transparent conductive film directly or via another layer. It is an optical member.
(6) A touch panel comprising the adhesive optical film for a touch panel according to (4) or the optical member for a touch panel according to (5).

By laminating the pressure-sensitive adhesive composition for a touch panel according to the present invention and indium tin oxide, which is a transparent conductive film, an achromatic color can be obtained as a whole, and thus an optical member for a touch panel and a touch panel excellent in color display properties are provided. can do.
Moreover, since the adhesive composition for touchscreens of this invention contains the porphyrin compound which has an absorption maximum in the wavelength range of 570 nm-605 nm, the adhesive composition for touchscreens which show a high light transmittance, and the adhesive optical film for touchscreens An optical member for a touch panel and a touch panel can be provided.
In addition, since the present invention uses a porphyrin compound as a pigment to be contained in the acrylic pressure-sensitive adhesive, the pressure-sensitive adhesive composition for a touch panel, a pressure-sensitive adhesive optical film for a touch panel, an optical member for a touch panel, and a touch panel are used. Can be provided.

It is a figure showing the spectrum of the adhesion type optical film in Example 2.

<Adhesive composition for touch panel>
The pressure-sensitive adhesive composition for touch panels of the present invention contains an acrylic pressure-sensitive adhesive and a porphyrin compound. The pressure-sensitive adhesive composition for a touch panel of the present invention has a blue color, and its L * value is preferably in the range of 90.0 to 100.0 or less, and the a * value is -1. It is preferably in the range of 0 to 1.0, and the b * value is preferably in the range of -6.0 to -0.1.
Since the total light transmittance tends to increase as the L * value increases, the L * value is preferably as high as possible. More preferably, it is 95.0 or more, More preferably, it is 99.0 or more.
Although the a * value of the transparent conductive film exhibiting yellow depends on the material, film thickness, manufacturing method, and the like, the a * value of the pressure-sensitive adhesive composition for touch panels is preferably near zero. A more preferred lower limit is -0.8, and a more preferred lower limit is -0.5. On the other hand, a more preferable upper limit value is 0.8, and a more preferable upper limit value is 0.5.
A more preferable lower limit value of b * value is −3.0, and a more preferable lower limit value is −1.5.
When L *, a *, and b * are within the above ranges, it is preferable that the color is easily achromatic when laminated with a yellow transparent conductive film.
The L * a * b * color system is a value obtained by measurement according to the method defined in JIS Z8729-1994. As a measuring method of JIS Z8729-1994, there are a measuring method by reflection and a measuring method by transmission. In this embodiment, a value measured by transmission is used.

In the L * a * b * color system, the L * value represents lightness, and the a * value and b * value represent color and saturation. Specifically, the L * value is indicated by a numerical value from 0 to 100, and becomes darker as it approaches 0 and becomes brighter as it approaches 100. If the a * value is a positive sign, it indicates a red color, and if it is a negative sign, it indicates a green color. If the b * value is a positive sign, it is a yellow color, and if it is a negative sign, it is a blue color. Further, for both the a * value and the b * value, the larger the absolute value, the greater the saturation of the color, and the brighter the color. The smaller the absolute value, the smaller the saturation.
In order to make an achromatic color strictly, it is necessary to set both a * value and b * value to 0. However, in the present invention, “achromatic value” means an a * value of −2.0 to 1.0. It is in the range and the b * value is in the range of -1.0 to 3.0.

(Porphyrin compound)
Since the porphyrin compound in the present invention has an absorption maximum in the wavelength range of 570 nm to 605 nm, when laminated with a pressure-sensitive adhesive composition for a touch panel and a transparent conductive film exhibiting a yellow color, the porphyrin compound can be achromatic and high. Total light transmittance can be obtained.
The total light transmittance in the present invention refers to a value measured according to JIS K7361.

  When the porphyrin compound in the present invention is used in combination with an acrylic pressure-sensitive adhesive, it is difficult for the pigment to deteriorate. In particular, as a porphyrin compound, it is preferable to use what is represented by the following general formula (1).

（式中、Ａ^１〜Ａ^８はそれぞれ独立に、水素原子、ハロゲン原子、ニトロ基、シアノ基、ヒドロキシ基、スルホン酸基、炭素数１〜２０のアルキル基、ハロゲノアルキル基、アルコキシ基、アルコキシアルコキシ基、アリールオキシ基、モノアルキルアミノ基、ジアルキルアミノ基、アラルキル基、アリール基、ヘテロアリール基、アルキルチオ基、又はアリールチオ基を表し、Ａ^１とＡ^２、Ａ^３とＡ^４、Ａ^５とＡ^６、Ａ^７とＡ^８はそれぞれ独立に、連結基を介して芳香族環を除く環を形成しても良く、Ｍは２個の水素原子、２価の金属原子、３価の１置換金属原子、４価の２置換金属原子、又はオキシ金属原子を表す。）

(In the formula, A ^{1 to} A ⁸ are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfonic acid group, an alkyl group having 1 to 20 carbon atoms, a halogenoalkyl group, an alkoxy group, an alkoxy group. Represents an alkoxy group, an aryloxy group, a monoalkylamino group, a dialkylamino group, an aralkyl group, an aryl group, a heteroaryl group, an alkylthio group, or an arylthio group, and A ¹ and A ² , A ³ and A ⁴ , A ⁵ and A ⁶ , A ⁷ and A ⁸ may each independently form a ring excluding an aromatic ring via a linking group, and M is two hydrogen atoms, a divalent metal atom, a trivalent mono-substitution Represents a metal atom, a tetravalent disubstituted metal atom, or an oxymetal atom.)

  By using the porphyrin compound, the pressure-sensitive adhesive composition for a touch panel can obtain a high total light transmittance of 90% or more. In addition, the pressure-sensitive adhesive composition for a touch panel of the present invention can obtain a total light transmittance of 95% or more, and further 96% or more. This is because the porphyrin compound has a maximum absorption region in a relatively narrow wavelength region. On the other hand, dyes other than porphyrin compounds (general-purpose dyes) have dyes with an absorption maximum near 600 nm. It is difficult to keep the total light transmittance to 90% or more while maintaining it.

(Acrylic adhesive)
In the pressure-sensitive adhesive composition for a touch panel of the present invention, an acrylic pressure-sensitive adhesive is used. The acrylic pressure-sensitive adhesive can easily obtain a high total light transmittance, and can obtain preferable adhesiveness. The acrylic pressure-sensitive adhesive preferably contains the following acrylic polymer.

Acrylic polymer The acrylic polymer preferably contains at least an alkyl (meth) acrylate monomer, and contains a functional group-containing polymer (carboxyl group-containing monomer, hydroxyl group-containing monomer, amino group-containing monomer, amide group-containing monomer, and epoxy group). More preferably, it is obtained by polymerizing at least one selected from the containing monomers) and the alkyl (meth) acrylate monomer. Among these polymers, in consideration of direct contact with the transparent conductive film, an alkyl (meth) acrylate {(meth) acrylic acid alkyl ester} monomer having 4 to 12 carbon atoms and a hydroxyl group-containing monomer are included. It is preferable to use an acrylic polymer obtained by polymerization. The acrylic polymer is preferably contained in an amount of 50 parts by mass or more with respect to 100 parts by mass of the solid component of the pressure-sensitive adhesive composition, and more preferably in the range of 60 to 99.9 parts by mass.

  Although it does not restrict | limit especially as alkyl (meth) acrylate (alkyl acrylate, alkyl methacrylate), For example, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl ( (Meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl ( Examples include meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, and dodecyl (meth) acrylate. In addition, the alkyl (meth) acrylate as a monomer component can be used individually or in combination of 2 or more types. Of these acrylates, n-butyl (meth) acrylate alone is particularly suitable. Although content of alkyl (meth) acrylate should just be 1-100 mass% in 100 mass parts of acrylic polymers, 50-99 mass% is suitable, and 70-98 mass% is still more suitable.

  Although it does not specifically limit as a carboxyl group-containing monomer, For example, (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, etc. are mentioned. In addition, anhydrides of these carboxyl group-containing monomers can also be used as the carboxyl group-containing monomer.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, and acrylic. 4-hydroxybutyl acid, 4-hydroxybutyl methacrylate, 2-hydroxy-3-chloropropyl acrylate, 2-hydroxy-3-chloropropyl methacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-methacrylic acid 2- And hydroxy-3-phenoxypropyl.

  Examples of the amino group-containing monomer include dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, and the like.

  Examples of the amide group-containing monomer include acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide and the like.

  Examples of the epoxy group-containing monomer include glycidyl acrylate, glycidyl methacrylate, acrylate-2-ethyl glycidyl ether, and methacrylic acid-2-glycidyl ether.

  The carboxyl group-containing monomer, the hydroxyl group-containing monomer, the amino group-containing monomer, the amide group-containing monomer, and the epoxy group-containing monomer act as a crosslinking point with the crosslinking agent. The monomer containing these functional groups is used in a proportion of 0.1 to 15% by mass. A hydroxyl group-containing monomer that does not corrode the transparent conductive film as a crosslinking point is preferably used.

  The acrylic polymer can be produced by a known polymerization method, and examples thereof include a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a polymerization method by ultraviolet irradiation. In addition, known polymerization initiators, chain transfer agents, and the like used in the polymerization can be appropriately used.

  The weight average molecular weight of the acrylic polymer is preferably 100,000 to 2,000,000, more preferably 300,000 to 1,500,000, and even more preferably 400,000 to 1,200,000.

  The acrylic polymer preferably has a glass transition temperature of less than 0 ° C., and is preferably less than −20 ° C. because the adhesiveness is further improved. The glass transition temperature is a shoulder value measured by a differential scanning calorimeter (DSC).

The acid value of the acrylic polymer is preferably from 0 to 300 mgKOH / g.
When directly laminating the pressure-sensitive adhesive composition for a touch panel according to the present invention and a transparent conductive film, the closer the acid value of the acrylic polymer constituting the pressure-sensitive adhesive composition is to 0, the more difficult it is to corrode the transparent conductive film, which is preferable. . Specifically, it is preferably 1 mg KOH / g or less. If it exceeds 1 mg KOH / g, the conductivity or transparency of the transparent conductive film is deteriorated, which is not preferable. When the acid value is 0, there is an advantage that the transparent conductive film is not corroded in the structure in contact with the transparent conductive film, and when the acid value is more than 300 mgKOH / g, the dye is likely to be deteriorated.

Various other known additives can be added to the adhesive composition for the optional component touch panel, but crosslinking agents, tackifiers, plasticizers, glass fibers, glass beads, metal powders, other inorganic powders, etc. It is also possible to use fillers, pigments, colorants, fillers, antioxidants, ultraviolet absorbers, and the like. Moreover, it is good also as a near-infrared absorption adhesive layer etc. which contain microparticles | fine-particles and show light diffusivity. Other near-infrared absorbing dyes may be added to the pressure-sensitive adhesive composition according to the present invention. Further, a visible light absorbing dye may be added to adjust the color tone. In addition, it is preferable that a rust inhibitor is added.

Crosslinking agent Moreover, it is suitable for the adhesive composition for touchscreens to contain the crosslinking agent. Examples of the crosslinking agent include an epoxy crosslinking agent, an isocyanate crosslinking agent, an imine crosslinking agent, and a peroxide crosslinking agent. Among these, an epoxy-based crosslinking agent and an isocyanate-based crosslinking agent are preferable.

  The epoxy-based crosslinking agent contains an epoxy compound, and examples of the epoxy compound include glycerin diglycidyl ether. The amount of the epoxy crosslinking agent used is 0.001 to 2 parts by mass, preferably 0.01 to 1 part by mass, and more preferably 0.02 to 0.5 parts by mass with respect to 100 parts by mass of the acrylic polymer. is there. When the amount of the epoxy compound used is less than 0.001 part by mass, it is not preferable in terms of adhesion to the optical film and durability.

  The isocyanate-based crosslinking agent contains an isocyanate compound. Examples of the isocyanate compound include tolylene diisocyanate, chlorophenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, water. Added isocyanate monomers such as diphenylmethane diisocyanate, adduct isocyanate compounds obtained by adding these isocyanate monomers with polyhydric alcohols such as trimethylolpropane, isocyanurate compounds, burette type compounds, and further known polyether polyols, polyester polyols, acrylics Polyol, polybutadiene polyol, polyisoprene polyol, etc. Such an addition-reacted urethane prepolymer type isocyanate. Among these isocyanate compounds, adduct isocyanate compounds such as xylylene diisocyanate are preferable from the viewpoint of improving the adhesion to the translucent substrate.

  The amount of the isocyanate crosslinking agent used is 0.001 to 5 parts by mass, preferably 0.01 to 3 parts by mass, and more preferably 0.02 to 2.5 parts by mass with respect to 100 parts by mass of the acrylic polymer. is there. When the amount of the isocyanate compound used is less than 0.001 part by mass, it is not preferable in terms of adhesion to the optical film and durability.

  In the pressure-sensitive adhesive composition for a touch panel of the present invention, the content of the porphyrin compound is preferably 0.0001 part by mass or more, more preferably 0.001 part by mass with respect to 100 parts by mass of the solid component of the acrylic adhesive. It is 0005 to 1 part by mass, and more preferably 0.001 to 0.5 part by mass. If it is less than the lower limit, it is difficult to obtain a preferable b * value, and if it exceeds the upper limit, the total light transmittance tends to be less than 90%.

<Adhesive optical film for touch panel>
By laminating the above-mentioned pressure-sensitive adhesive composition for a touch panel on a translucent substrate, a pressure-sensitive adhesive optical film for a touch panel can be obtained. The light-transmitting substrate and the pressure-sensitive adhesive composition may be laminated adjacent to each other, or may have another layer between the light-transmitting substrate and the pressure-sensitive adhesive composition. May have other layers. Moreover, you may laminate | stack a translucent base | substrate on both surfaces of an adhesive composition.
Here, as other layers, for example, a hard coat layer, a polarizing layer, a light diffusion layer, a low reflection layer, an antifouling layer, an antistatic layer, an ultraviolet / near infrared (NIR) absorption layer, an electromagnetic wave shielding layer, an adhesive layer ( Adhesive layer).
When laminating the pressure-sensitive adhesive composition adjacent to the light-transmitting substrate, the acrylic pressure-sensitive adhesive, porphyrin compound and other optional components were mixed and coated on the light-transmitting substrate as a paint (adhesive layer forming paint). Then, after drying the paint, a pressure-sensitive adhesive optical film for a touch panel can be formed by applying a curing treatment (heat or ionizing radiation) as necessary.

  As a method for applying the adhesive layer-forming coating material on the translucent substrate, a normal coating method or printing method is applied. Specifically, air doctor coating, bar coating, blade coating, knife coating, reverse coating, transfer roll coating, gravure roll coating, kiss coating, cast coating, spray coating, slot orifice coating, calendar coating, dam coating, dip coating Coating such as die coating, intaglio printing such as gravure printing, printing such as stencil printing such as screen printing, and the like can be used.

(Translucent substrate)
The translucent substrate according to the best mode is not particularly limited as long as it is translucent, and glass such as quartz glass and soda glass can also be used. Polyethylene terephthalate (PET), triacetyl cellulose (TAC) , Polyethylene naphthalate (PEN), polymethyl methacrylate (PMMA), polycarbonate (PC), polyimide (PI), polyethylene (PE), polypropylene (PP), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), cycloolefin Various resin films such as a copolymer (COC), a norbornene-containing resin, an acrylic resin, polyethersulfone, cellophane, and aromatic polyamide can be suitably used.
A release layer can also be provided on the surface (one side or both sides) of these various resin films.

The higher the transparency of these translucent substrates, the better. However, the total light transmittance (JIS K7105) is 80% or more, more preferably 90% or more. Further, the thickness of the translucent substrate is preferably thin from the viewpoint of weight reduction, but considering the productivity and handling property, the one in the range of 1 to 700 μm, preferably 25 to 250 μm is used. Is preferred.

It is also possible to apply treatments such as alkali treatment, corona treatment, plasma treatment and sputtering treatment, primer coating such as surfactant and silane coupling agent, and thin film dry coating such as Si deposition on the surface of the translucent substrate. is there.

<Optical member for touch panel>
By laminating the pressure-sensitive adhesive composition for a touch panel according to the present invention with a transparent conductive film exhibiting yellow, an optical member for a touch panel can be obtained. The pressure-sensitive adhesive composition for touch panel and the transparent conductive film may be laminated adjacent to each other, or another layer may be provided between the pressure-sensitive adhesive composition for touch panel and the transparent conductive film.
Here, as the other layers, the same layers as those exemplified for the pressure-sensitive adhesive optical film for touch panels can be used.
The transparent conductive film that can be made achromatic by the pressure-sensitive adhesive composition for a touch panel of the present invention has an a * value of −2.0 to 1.0 and a b * value of 0.1 to 6.0. It is what.
When the pressure-sensitive adhesive composition for a touch panel according to the present invention and a transparent conductive film exhibiting yellow are laminated, the L * value is 80.0 or more, the a * value is in the range of -1.0 to 1.0, The b * value is preferably in the range of -1.0 to 3.0. A more preferable L * value is 85.0 or more, and further preferably 90.0 or more. A more preferable a * value is −0.5 or more and 0.5 or less.
A more preferred b * value is 0.1 to 3.0.

(Transparent conductive film)
Examples of the material of the transparent conductive film having the a * value and the b * value as described above include indium oxide, tin oxide, zinc oxide, indium tin oxide, tin-antimony composite oxide, zinc-aluminum composite oxide, indium- Examples thereof include a zinc composite oxide, silver and silver alloy, copper and copper alloy, gold and the like having a single layer or a laminated structure of two or more layers. Among these, indium tin oxide exhibits the above-mentioned color as a single layer or a single layer.

The thickness of the transparent conductive film is preferably in the range of 4 to 200 nm, particularly preferably 5 to 100 nm. When the film thickness of the transparent conductive film is less than 4 nm, it tends to be difficult to form a continuous thin film and to exhibit good conductivity. On the other hand, when it is thicker than 200 nm, it is difficult to achieve both color display properties and transparency when incorporated in a display.

As a method for forming a transparent conductive film, a vacuum deposition method, a sputtering method, a CVD method, an ion plating method, a spray method, and the like are known, and the above method is appropriately used according to a required film thickness. Can do.

For example, in the case of the sputtering method, a normal sputtering method using an oxide target, a reactive sputtering method using a metal target, or the like is used. At this time, oxygen, nitrogen, or the like may be introduced as a reactive gas, or means such as ozone addition, plasma irradiation, or ion assist may be used in combination. In addition, a bias such as direct current, alternating current, and high frequency may be applied to the substrate as long as the object of the present invention is not impaired.

<Touch panel>
By using the pressure-sensitive adhesive composition for a touch panel according to the present invention for a touch panel using a transparent conductive film, the touch panel can be brought close to an achromatic color. Examples of such a touch panel include a resistance film method and a capacitance method.
Moreover, as long as the light radiate | emitted to an observation surface side should be achromatic, the lamination | stacking position of the adhesive composition for touchscreens is not limited, For example, you may provide in an observation surface side, and a light source It may be provided on the side.

Hereinafter, the present invention will be described using examples.

(Preparation of acrylic adhesive)
As monomers, butyl acrylate (427.3 g), ethyl acrylate (171.2 g), 4-hydroxybutyl (meth) acrylate (1.5 g) were weighed and mixed thoroughly to obtain a polymerizable monomer mixture (a1). . Next, 300 g of this polymerizable monomer mixture (a1) and 160 g of ethyl acetate were placed in a flask. Also, add 300 g of the polymerizable monomer mixture (a1), 16 g of ethyl acetate and 0.15 g of 2,2′-azobis (4-methoxy-2,4-dimethyl) valeronitrile in the dropping funnel and mix well. A dropping mixture (a2) was prepared.

  Next, while flowing nitrogen gas at a rate of 20 ml / min, the internal temperature of the flask was raised to 95 ° C., and 2,2′-azobis (4-methoxy-2,4-dimethyl) valeronitrile as a polymerization initiator. (0.15 g) was charged into the flask to initiate the polymerization reaction. And the mixture (a2) for dripping was dripped at this flask over 90 minutes from the dropping funnel. After completion of the dropwise addition of the mixture for dropping (a2), the mixture was aged for 6 hours while being diluted with ethyl acetate as the viscosity increased. After completion of the reaction, an acrylic pressure-sensitive adhesive a3 having a weight average molecular weight of 600,000 and an acid value of 0 mgKOH / g was obtained.

Example 1
Dye PD-320 (manufactured by Yamamoto Kasei Co., Ltd., having a maximum absorption in the wavelength range of 570 nm to 605 nm) is dissolved in methyl ethyl ketone (hereinafter referred to as MEK) to prepare a dye solution A4 having a solid content of 1%. did.
Furthermore, isocyanate type curing agent Coronate L (manufactured by Nippon Polyurethane Industry) was dissolved in MEK as a crosslinking agent to prepare a crosslinking agent solution B5 having a solid content of 10%.
Then, in 100 parts by mass of the above acrylic pressure-sensitive adhesive a3, 0.015 parts by mass of the dye solution A4 and 0.9 part by mass of the cross-linking agent solution B5 are added and mixed in a solid content ratio, and the pressure-sensitive adhesive a1 Got.

（式中、Ａ^１〜Ａ^８はそれぞれ独立に、水素原子、ハロゲン原子、ニトロ基、シアノ基、ヒドロキシ基、スルホン酸基、炭素数１〜２０のアルキル基、ハロゲノアルキル基、アルコキシ基、アルコキシアルコキシ基、アリールオキシ基、モノアルキルアミノ基、ジアルキルアミノ基、アラルキル基、アリール基、ヘテロアリール基、アルキルチオ基、又はアリールチオ基を表し、Ａ^１とＡ^２、Ａ^３とＡ^４、Ａ^５とＡ^６、Ａ^７とＡ^８はそれぞれ独立に、連結基を介して芳香族環を除く環を形成しても良く、Ｍは２個の水素原子、２価の金属原子、３価の１置換金属原子、４価の２置換金属原子、又はオキシ金属原子を表す。）

(In the formula, A ^{1 to} A ⁸ are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfonic acid group, an alkyl group having 1 to 20 carbon atoms, a halogenoalkyl group, an alkoxy group, an alkoxy group. Represents an alkoxy group, an aryloxy group, a monoalkylamino group, a dialkylamino group, an aralkyl group, an aryl group, a heteroaryl group, an alkylthio group, or an arylthio group, and A ¹ and A ² , A ³ and A ⁴ , A ⁵ and A ⁶ , A ⁷ and A ⁸ may each independently form a ring excluding an aromatic ring via a linking group, and M is two hydrogen atoms, a divalent metal atom, a trivalent mono-substitution Represents a metal atom, a tetravalent disubstituted metal atom, or an oxymetal atom.)

The pressure-sensitive adhesive a1 prepared as described above was applied to release PET (product name: PET38C, manufactured by Lintec) with an applicator. The thickness at the time of coating was adjusted so that the thickness of the adhesive after drying was 25 μm. Subsequently, it was dried in an oven at 80 ° C. for 2 minutes. A release film (manufactured by Lintec, trade name: PET3801) was bonded to the layer made of the adhesive a, and cured at room temperature for 7 days to produce an adhesive optical film of Example 1.
The pressure-sensitive adhesive optical film of Example 1 is obtained by laminating the pressure-sensitive adhesive composition for a touch panel of the present invention on a translucent substrate.

[Example 2]
Instead of the adhesive a1, an adhesive prepared by adding and mixing the pigment solution A4 in a solid content ratio of 0.010 parts by mass and the cross-linking agent solution B5 in 0.9 parts by mass in 100 parts by mass of the acrylic adhesive a3 A pressure-sensitive adhesive optical film of Example 2 was obtained in the same manner as Example 1 except that the agent a2 was used.
The pressure-sensitive adhesive optical film of Example 2 is obtained by laminating the pressure-sensitive adhesive composition for a touch panel of the present invention on a translucent substrate.

[Example 3]
In place of the pressure-sensitive adhesive a1, a pressure-sensitive adhesive prepared by adding and mixing 100 parts by mass of an acrylic pressure-sensitive adhesive a3 in a solid content ratio of 0.005 parts by mass of the dye solution A4 and 0.9 parts by mass of the cross-linking agent solution B5 A pressure-sensitive adhesive optical film of Example 3 was obtained in the same manner as in Example 1 except that the agent a3 was used.
The pressure-sensitive adhesive optical film of Example 3 is obtained by laminating the pressure-sensitive adhesive composition for a touch panel of the present invention on a translucent substrate.

[Example 4]
In place of the pressure-sensitive adhesive a1, a pressure-sensitive adhesive prepared by adding and mixing the pigment solution A4 in 0.002 parts by mass and the cross-linking agent solution B5 in 0.9 parts by mass in 100 parts by mass of the acrylic pressure-sensitive adhesive a3 A pressure-sensitive adhesive optical film of Example 4 was obtained in the same manner as in Example 1 except that the agent a4 was used.
The pressure-sensitive adhesive optical film of Example 4 is obtained by laminating the pressure-sensitive adhesive composition for a touch panel of the present invention on a translucent substrate.

Table 1 shows the type and amount of the dye solution contained in each pressure-sensitive adhesive used in the above-mentioned pressure-sensitive adhesive optical film and the amount of the crosslinking agent solution.

<Evaluation 1-1>
The light release side release PET was peeled off from each of the above adhesive optical films, and was bonded to easy-adhesion-treated optical PET (trade name: Cosmo Shine A4300, manufactured by Toyobo Co., Ltd.). Furthermore, the heavy release side release PET was peeled off from each adhesive optical film to obtain an adhesive optical film for evaluation test.
The transmission spectrum and the color tone were measured with a spectrophotometer (manufactured by Shimadzu Corporation, trade name: UV3150) for each of the obtained adhesive optical films for evaluation tests. The color tone was measured according to JIS Z8729-1994.
The transmission spectrum of the adhesive optical film of Example 2 is shown in FIG. 1, and the color tone of each Example is shown in Table 2. As is clear from FIG. 1, the adhesive optical film of Example 2 has an absorption maximum in the wavelength range of 570 nm to 605 nm.

<Evaluation 1-2>
Further, the total light transmittance of the pressure-sensitive adhesive optical film for the evaluation test was measured with a haze meter (manufactured by Nippon Denshoku Co., Ltd., trade name: NDH2000) according to JIS K7361. The respective measurement results are shown in Table 2.
In addition, the measurement measured the adhesive film for evaluation tests after performing a baseline measurement with the easy-adhesion-processed optical PET alone.

<Evaluation 2>
The light release PET is peeled off from each of the adhesive optical films of Examples 1 to 4, the exposed adhesive layer surface is bonded to the transparent conductive film surface of an ITO film (trade name TT115, manufactured by Toyobo Co., Ltd.), and the heavy release side release PET is further removed. It peeled and it was set as the optical member for touchscreens of Examples 5-8.
With respect to each obtained optical member, a transmission spectrum and a color tone were measured with a spectrophotometer (manufactured by Shimadzu Corporation, trade name: UV3150), and a haze meter (manufactured by Nippon Denshoku, trade name: NDH2000) was measured according to JIS K7361. Were used to measure the total light transmittance, and the measurement results are shown in Table 3. The color tone was measured according to JIS Z8729-1994.

The pressure-sensitive adhesive optical films of Examples 1 to 4 using the pressure-sensitive adhesive composition for a touch panel of the present invention have a blue color and have an absorption maximum in the region of 570 nm to 605 nm. High total light transmittance can be achieved. Moreover, the optical member of Examples 5-8 using the adhesive composition for touchscreens of this invention has a * value in the range of -2.0-1.0, and b * value is -2. Since it exists in the range of 0-3.0, it can be brought closer to an achromatic color and the touch panel which is excellent in color display property can be provided.
In addition, since the present invention uses a porphyrin compound as a pigment to be contained in the acrylic pressure-sensitive adhesive, the pressure-sensitive adhesive composition for a touch panel, a pressure-sensitive adhesive optical film for a touch panel, an optical member for a touch panel, and a touch panel are used. Can be provided.

Claims (6)

  A pressure-sensitive adhesive composition for a touch panel containing an acrylic pressure-sensitive adhesive and a porphyrin compound. The pressure-sensitive adhesive composition for a touch panel according to claim 1, wherein the porphyrin compound is represented by the following general formula (1).

(In the formula, A ^{1 to} A ⁸ are each independently a hydrogen atom, a halogen atom, a nitro group, a cyano group, a hydroxy group, a sulfonic acid group, an alkyl group having 1 to 20 carbon atoms, a halogenoalkyl group, an alkoxy group, an alkoxy group. Represents an alkoxy group, an aryloxy group, a monoalkylamino group, a dialkylamino group, an aralkyl group, an aryl group, a heteroaryl group, an alkylthio group, or an arylthio group, and A ¹ and A ² , A ³ and A ⁴ , A ⁵ and A ⁶ , A ⁷ and A ⁸ may each independently form a ring excluding an aromatic ring via a linking group, and M is two hydrogen atoms, a divalent metal atom, a trivalent mono-substitution Represents a metal atom, a tetravalent disubstituted metal atom, or an oxymetal atom.)   The pressure-sensitive adhesive composition for a touch panel according to claim 1, wherein 0.0001 parts by mass or more of the porphyrin compound is blended with respect to 100 parts by mass of the acrylic pressure-sensitive adhesive.   A pressure-sensitive adhesive optical film for a touch panel, wherein the pressure-sensitive adhesive composition for a touch panel according to any one of claims 1 to 3 is laminated directly or via another layer on a translucent substrate.   An optical member for a touch panel, wherein the adhesive composition for a touch panel according to any one of claims 1 to 3 is laminated directly or via another layer on a transparent conductive film. A touch panel comprising the adhesive optical film for a touch panel according to claim 4 or the optical member for a touch panel according to claim 5.

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