JP2010144002A - Double-sided sticky sheet for use in transparent electroconductive film fixation, transparent electroconductive film laminate, and touch panel device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double-sided sticky sheet which causes no corrosion of an electroconductive layer even when pasting directly to the surface of an electroconductive layer of a transparent electroconductive film and causes hardly the peeling under a condition of high temperatures and which is excellent in the cohesive force of an adhesive layer and in the durability. <P>SOLUTION: This double-sided sticky sheet for use in the transparent electroconductive film fixation of a double sided sticky sheet for pasting onto the electroconductive layer surface of a transparent electroconductive film, has an adhesive layer comprising an adhesive composition which includes (A) a carboxylic group-containing (meth)acrylate copolymer and (B) a nitrogen atom-containing (meth)acrylate copolymer, and the equivalent ratio of carboxylic groups of (A) the carboxylic group-containing (meth)acrylate copolymer to nitrogen atoms of (B) a nitrogen atom-containing (meth)acrylate copolymer is 1:0.05-1:0.5, consequently the containing of a specified amount of the nitrogen atom-containing component to the acid component permits lowering the corrosive property against the transparent electroconductive film and moreover permits reconciling the high cohesive force of the adhesive layer and the high adhesiveness to the transparent electroconductive film. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a double-sided pressure-sensitive adhesive sheet to be attached to a transparent conductive film, a transparent conductive film laminate using the double-sided pressure-sensitive adhesive sheet, and a touch panel device using the transparent conductive film laminate.

  In recent years, touch sensors have begun to be mounted on portable devices. Touch sensors for mobile devices are mainly equipped with a resistive touch panel that detects the pressure at the time of input and a capacitive touch panel that detects the input location by static electricity from the human body at the time of input. In view of the multi-functionality of the input method, the capacitive method is becoming mainstream. A transparent conductive film in which a conductive layer is provided on a transparent substrate or glass is used for the touch panel, and in the capacitive touch panel, the conductive layer surface of the transparent conductive film is a pressure-sensitive adhesive of a double-sided pressure-sensitive adhesive sheet. It is fixed so as to contact the surface of the layer.

  The conductive layer of the transparent conductive film is formed by depositing a metal having high transparency and conductivity, such as indium tin oxide, and a double-sided pressure-sensitive adhesive sheet is used so that the pressure-sensitive adhesive layer is in contact with the conductive layer surface of the conductive film. In the case of lamination, there is a problem that a metal oxidation reaction occurs due to the double-sided pressure-sensitive adhesive sheet and the conductive function is lowered. For this reason, high metal corrosion prevention property is requested | required by the double-sided adhesive sheet for transparent conductive film fixation.

  As a double-sided PSA sheet having metal corrosion prevention properties, a double-sided PSA sheet that does not contain an acid component (see, for example, Patent Document 1) or metal corrosion because the acid component contained in the PSA layer is a cause of metal corrosion. A double-sided PSA sheet containing an inhibitor (see, for example, Patent Document 2) has been proposed.

  These double-sided PSA sheets have metal corrosion prevention properties due to a specific PSA layer. However, the double-sided pressure-sensitive adhesive sheet containing no acid component has problems such as a decrease in punching processability due to insufficient cohesive force of the pressure-sensitive adhesive layer and peeling of the transparent conductive film due to insufficient adhesion to the adherend.

  Moreover, the double-sided pressure-sensitive adhesive sheet containing a metal corrosion inhibitor has a problem that the metal corrosion inhibitor is discolored in a durability test and optical properties are deteriorated.

JP 2005-325250 A JP 2006-45315 A

  The problem to be solved by the present invention is that the conductive layer is not corroded even if directly bonded to the conductive layer surface of the transparent conductive film, and the cohesive force of the pressure-sensitive adhesive layer is excellent, and peeling occurs under high temperature conditions. It is difficult to provide a double-sided pressure-sensitive adhesive sheet having excellent durability.

  In the present invention, the acid component of the pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet contains a specific amount of a nitrogen atom-containing component, thereby reducing the corrosiveness to the transparent conductive film, A double-sided PSA sheet that has both high adhesion to a transparent conductive film has been realized.

  That is, the present invention is a double-sided pressure-sensitive adhesive sheet to be bonded to a conductive layer surface of a transparent conductive film, wherein the pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet comprises a carboxyl group-containing (meth) acrylate copolymer (A) and a nitrogen atom. A pressure-sensitive adhesive composition having a (meth) acrylic acid ester copolymer (B), and a carboxyl group of the carboxyl group-containing (meth) acrylic acid ester copolymer (A) in the pressure-sensitive adhesive composition; Provided is a double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film, wherein the equivalent ratio of nitrogen atom-containing (meth) acrylic acid ester copolymer (B) to nitrogen atoms is 1: 0.05 to 1: 0.5. .

  In the double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film of the present invention, a specific amount of nitrogen-containing (meth) acrylic acid ester copolymer is blended with respect to the acid component in the pressure-sensitive adhesive layer. Corrosion of the conductive layer surface can be suppressed, cohesive force is increased, punching workability is excellent, adhesion to the transparent conductive film is increased, and peeling of the transparent conductive film can be suppressed.

  In the double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film of the present invention, the pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet comprises a carboxyl group-containing (meth) acrylate copolymer (A) and a nitrogen atom-containing (meth) acrylate ester. It comprises a pressure-sensitive adhesive composition having a polymer (B), the carboxyl group-containing (meth) acrylic acid ester copolymer (A) in the pressure-sensitive adhesive composition, and a nitrogen atom-containing (meth) acrylic acid. It is a double-sided pressure-sensitive adhesive sheet having an equivalent ratio with the nitrogen atom of the ester copolymer (B) of 1: 0.05 to 1: 0.5.

[Carboxyl group-containing (meth) acrylic acid ester copolymer (A)]
The carboxyl group-containing (meth) acrylic acid ester copolymer (A) used in the present invention is mainly composed of a (meth) acrylic acid ester monomer having 2 to 14 carbon atoms, and contains a carboxyl group-containing (meth) acrylic acid. It is a polymer in which an ester monomer is copolymerized. By using the (meth) acrylic acid ester having 2 to 14 carbon atoms as a main component, it is possible to impart adhesive force or optical characteristics necessary for fixing the transparent conductive film to the pressure-sensitive adhesive layer. Moreover, the cohesive force required in order to fix a transparent conductive film can be provided to an adhesive layer by copolymerizing a carboxyl group-containing (meth) acrylic acid ester monomer.

  In the present specification, acrylic acid and methacrylic acid are collectively referred to as (meth) acrylic acid, and these derivatives are also represented in the same manner.

  Specific examples of the (meth) acrylic acid ester monomer having 2 to 14 carbon atoms include ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, t-butyl acrylate, n -Hexyl acrylate, cyclohexyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, isodecyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate , Sec-butyl methacrylate, t-butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, - octyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, isononyl methacrylate, isodecyl methacrylate, lauryl methacrylate and the like.

  Among them, a methacrylic acid alkyl ester monomer having an alkyl side chain having 4 to 9 carbon atoms or an acrylic acid alkyl ester monomer having an alkyl side chain having 4 to 9 carbon atoms is preferable, and the carbon number is More preferred are alkyl acrylate monomers having 4 to 9 alkyl side chains. Of these, n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferable. By using a (meth) acrylic acid alkyl ester having an alkyl side chain with a carbon number within the above range, high adhesiveness can be imparted to the transparent conductive film.

  The content of the (meth) acrylic acid ester monomer having 2 to 14 carbon atoms in the carboxyl group-containing (meth) acrylic acid ester copolymer (A) is preferably 90 to 99% by mass, 90 to More preferably, it is 96 mass%. By making the content of the (meth) acrylic acid ester monomer having 2 to 14 carbon atoms in the carboxyl group-containing (meth) acrylic acid ester copolymer (A) within the above range, the adhesive layer has a transparent conductive property. Adhesiveness necessary for fixing the membrane can be suitably imparted.

  Examples of the carboxyl group-containing (meth) acrylic acid ester monomer include acrylic acid, methacrylic acid, itaconic acid, maleic acid, crotonic acid, acrylic acid dimer, and ethylene oxide-modified succinic acid acrylate. Of these, acrylic acid is preferred because of its high versatility.

  The content of the carboxyl group-containing (meth) acrylic acid ester monomer in the monomer component constituting the carboxyl group-containing (meth) acrylic acid ester copolymer (A) is a single amount constituting the copolymer. It is preferable to set it as 1-20 mass% with respect to the total amount of a body component, and it is more preferable to set it as 4-20 mass%. By setting the content in this range, a cohesive force necessary for fixing the transparent conductive film to the pressure-sensitive adhesive layer can be suitably imparted.

  It is also preferable to use a vinyl monomer having a functional group that reacts with the crosslinking agent in order to increase the cohesive force of the pressure-sensitive adhesive layer by suitably crosslinking with the crosslinking agent. The vinyl monomer having a functional group that reacts with the crosslinking agent is not particularly limited, and examples thereof include hydroxyl group-containing vinyl monomers such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and 4-hydroxybutyl acrylate. Of these, 4-hydroxybutyl acrylate is preferable. It is preferable that the usage-amount of the vinyl monomer which has a functional group is 0.01 mass%-1.0 mass% in the monomer component which comprises an acrylic copolymer, and it is 0.03-0.5 mass%. Is particularly preferred.

  The weight average molecular weight Mw of the carboxyl group-containing (meth) acrylic acid ester copolymer (A) is preferably 500,000 to 2,000,000, more preferably 600,000 to 1,800,000, and even more preferably 700,000 to 1,600,000. . When the weight average molecular weight Mw of the carboxyl group-containing (meth) acrylic acid ester copolymer (A) is within the above range, an adhesive force necessary for fixing the transparent conductive film can be suitably imparted.

In the present invention, the weight average molecular weight Mw of the carboxyl group-containing (meth) acrylic acid ester copolymer (A) can be measured by gel permeation chromatography (GPC). More specifically, as a GPC measurement device, “SC8020” manufactured by Tosoh Corporation can be used to measure and obtain the following GPC measurement conditions based on polystyrene conversion values.
(GPC measurement conditions)
Sample concentration: 0.5% by weight (tetrahydrofuran solution)
Sample injection volume: 100 μL
・ Eluent: Tetrahydrofuran (THF)
・ Flow rate: 1.0 mL / min
Column temperature (measurement temperature): 40 ° C
Column: “TSKgel GMHHR-H” manufactured by Tosoh Corporation
・ Detector: Differential refraction

[Nitrogen atom-containing (meth) acrylic acid ester copolymer (B)]
The nitrogen atom-containing (meth) acrylic acid ester copolymer (B) used in the present invention is mainly composed of a methacrylic acid ester monomer having 1 to 8 carbon atoms, and the nitrogen atom-containing copolymerizable monomer is It is a copolymerized polymer. By using the (meth) acrylic acid ester having 1 to 8 carbon atoms as a main component, it is possible to impart cohesive force and adhesiveness necessary for fixing the transparent conductive film. Moreover, by copolymerizing the nitrogen atom-containing copolymerizable monomer, compatibility with the carboxyl group-containing (meth) acrylic acid ester copolymer (A) is improved, and excellent optical properties can be imparted.

  Specific examples of the (meth) acrylic acid ester monomer having 1 to 8 carbon atoms include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, and t-butyl. Acrylate, n-hexyl acrylate, cyclohexyl acrylate, n-octyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, t- Butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate , 2-ethylhexyl methacrylate and the like.

  Among these, a methacrylic acid alkyl ester monomer having an alkyl side chain having 1 to 4 carbon atoms is preferable. Of these, methyl methacrylate is particularly preferable. By using a methacrylic acid alkyl ester monomer having an alkyl side chain having the carbon number within the above range, a cohesive force necessary for fixing the transparent conductive film can be suitably imparted.

  The content of the (meth) acrylic acid ester monomer having 1 to 8 carbon atoms in the monomer component constituting the nitrogen atom-containing (meth) acrylic acid ester copolymer (B) is 70 to 99% by mass. It is preferable to make it 90 to 98% by mass. Transparent to the pressure-sensitive adhesive layer by adjusting the content of the (meth) acrylic acid ester monomer having 1 to 8 carbon atoms in the nitrogen atom-containing (meth) acrylic acid ester copolymer (B) within the range. Adhesiveness and cohesive force necessary for fixing the conductive film can be suitably imparted.

  As the nitrogen atom-containing copolymerizable monomer, there is no problem as long as it contains a nitrogen atom and can be copolymerized with the (meth) acrylic acid ester monomer having 1 to 8 carbon atoms. Examples thereof include a group-containing monomer, an amide group-containing monomer, a nitrogen-based heterocycle-containing monomer, a cyano group-containing monomer, and an imide group-containing monomer. Examples of these monomers include amino group-containing monomers such as aminomethyl (meth) acrylate, aminoethyl (meth) acrylate, aminopropyl (meth) acrylate, and aminoisopropyl (meth) acrylate. (Meth) acrylic acid aminoalkyl and (meth) acrylic acid (N-substituted) aminoalkyl. Examples of the (meth) acrylic acid (N-substituted) aminoalkyl include (meth) acrylic acid N-alkylaminoalkyl such as N- (t-butyl) aminoethyl (meth) acrylate; (meth) acrylic acid Examples include N, N-dialkylaminoalkyl (meth) acrylates such as N, N-dimethylaminoethyl and N, N-dimethylaminopropyl (meth) acrylate.

  Of these, amino group-containing monomers and amide group-containing monomers are preferred. Of these, amino group-containing monomers are particularly preferred. By using the nitrogen-containing copolymerizable monomer, excellent optical properties can be imparted to the pressure-sensitive adhesive layer.

  Content of the nitrogen atom containing copolymerizable monomer in the monomer component which comprises a nitrogen atom containing (meth) acrylic acid ester copolymer (B) is 1-30 with respect to the total amount of the said copolymer. It is preferable to set it as weight%, and it is more preferable to set it as 1-20 mass%. In order to fix the transparent conductive film to the pressure-sensitive adhesive layer by adjusting the content of the nitrogen atom-containing copolymerizable monomer in the nitrogen atom-containing (meth) acrylic acid ester copolymer (B) in this range. Necessary cohesive force can be imparted.

  The weight average molecular weight Mw of the nitrogen atom-containing (meth) acrylic acid ester copolymer (B) is preferably 5,000 to 100,000, more preferably 5,000 to 80,000, and further preferably 5,000 to 50,000. When the weight average molecular weight Mw of the nitrogen atom-containing (meth) acrylic acid ester copolymer (B) is within the above range, an adhesive force necessary for fixing the transparent conductive film can be suitably imparted.

[Adhesive composition]
The pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film of the present invention comprises the carboxyl group-containing (meth) acrylic acid ester copolymer (A) and a nitrogen atom-containing (meth) acrylic acid. The carboxyl group of the carboxyl group-containing (meth) acrylic acid ester copolymer (A) in the pressure-sensitive adhesive composition and the nitrogen atom-containing (meth) acrylic acid ester copolymer having an ester copolymer (B) The equivalent ratio of (B) to nitrogen atoms is 1: 0.05 to 1: 0.5, preferably 1: 0.05 to 1: 0.3, and more preferably 1: 0.05 to 0.2. preferable. By blending the copolymers (A) and (B) within the above range, the corrosion of the conductive layer of the transparent conductive film can be controlled, and further, the double-sided pressure-sensitive adhesive sheet has excellent adhesion performance to the transparent conductive film. It can be given to the pressure-sensitive adhesive layer.

  Moreover, 1-50 mass% is preferable, and nitrogen atom containing (meth) acrylic acid ester copolymer (B) is preferable with respect to 100 mass% of carboxyl group-containing (meth) acrylic acid ester copolymer (A), 40 mass% is more preferable, and 5-30 mass% is further more preferable. By blending the copolymers (A) and (B) within the above range, excellent adhesive performance and cohesive force can be imparted to the double-sided PSA sheet.

  In the said adhesive composition, in order to raise the cohesion force of an adhesive layer as components other than the said copolymer (A) and (B), it is preferable to contain a crosslinking agent.

  Examples of the crosslinking agent used include isocyanate crosslinking agents, epoxy crosslinking agents, chelating crosslinking agents, azirine crosslinking agents, and polyfunctional acrylates. Among them, an isocyanate-based crosslinking agent or an epoxy-based crosslinking agent that is highly reactive with the component (A) of the (meth) acrylic copolymer is preferable.

  0.1-5 mass parts is preferable, as for the compounding quantity of the crosslinking agent added to the adhesive layer of the said double-sided adhesive sheet, 0.1-3 mass parts is more preferable, and 0.1-1.5 mass parts is further preferable. By setting the content of the crosslinking agent in this range, it is easy to adjust the gel fraction of the pressure-sensitive adhesive layer to a suitable range.

[Double-sided adhesive sheet for fixing transparent conductive film]
Since the double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film of the present invention has a pressure-sensitive adhesive layer made of the above-mentioned pressure-sensitive adhesive composition, it can be suitably bonded to the conductive layer of the transparent conductive film, and corrosion of the conductive layer hardly occurs.

  The double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film of the present invention may be a double-sided pressure-sensitive adhesive sheet having only a pressure-sensitive adhesive layer without having a base material. Moreover, even if the adhesive layer consists of a single layer, multiple layers may be laminated | stacked. Especially, it is preferable that it is a double-sided adhesive sheet which does not have a base material but consists only of an adhesive layer from a viewpoint of ensuring transparency and shape followability.

  When the double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film of the present invention has a substrate, a transparent substrate can be used as the substrate. As the transparent substrate, for example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene film, polypropylene film, cellophane, diacetyl cellulose film, triacetyl cellulose film, acetyl cellulose butyrate film, polyvinyl chloride film, polyvinyl chloride Vinylidene film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyetheretherketone film, polyethersulfone film, polyetherimide film, polyimide film, fluorine Resin film, nylon film, acrylic resin film, etc. Rukoto can. Of these, an acrylic resin film is preferable. When the base material is used, for example, the refractive index of the acrylic resin film is 1.45 to 1.49, and the refractive index of the pressure-sensitive adhesive layer is about 1.47. The difference in refractive index between the two is low, and reflection loss between the pressure-sensitive adhesive layer and the transparent substrate is easily suppressed.

  In addition, for the purpose of improving the adhesiveness with the pressure-sensitive adhesive layer, the film substrate is subjected to surface unevenness treatment by sandblasting method or solvent treatment method, or corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, Surface treatment such as surface oxidation treatment such as ozone / ultraviolet irradiation treatment can be performed.

The pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film of the present invention preferably has a gel fraction represented by the following formula of 30 to 90% when immersed in toluene for 24 hours, and 40 to 80 % Is more preferable, and 50 to 80% is most preferable. When the gel fraction of the pressure-sensitive adhesive layer is within the above range, it is easy to suppress peeling over time in fixing the transparent conductive film, and it is easy to suppress stringing from the processed end face during punching.
Gel fraction (%) = [(mass after immersion of toluene in double-sided PSA sheet) / (mass before immersion of toluene in double-sided PSA sheet)] × 100

  The double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film of the present invention has a total light transmittance of 90% or more immediately after standing for 100 hours at 60 ° C. and 90% RH so that the transparency of the transparent conductive film is not impaired. It is preferable that it is 1.0% or less. If it is within the above range, the display equipped with the touch panel device using the double-sided pressure-sensitive adhesive sheet can easily maintain high definition even under high temperature and high humidity conditions. In order to make the total light transmittance and haze within the above ranges, it is easy to achieve by setting the amount of the copolymer (B) to 1 to 50% by mass relative to 100% by mass of the copolymer (A). .

  The water absorption rate of the pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film of the present invention is preferably 2.0% or less after standing at 60 ° C. and 90% RH. By controlling the water absorption rate of the double-sided PSA sheet within the above range, it is easy to maintain the double-sided PSA sheet transparent even under high-temperature and high-humidity conditions, and moisture is one of the causes of corrosion of the conductive layer of the transparent conductive film. Therefore, it is easy to suppress corrosion of the conductive film layer of the transparent conductive film. In order to make a water absorption into the said range, it is easy to achieve by making content of the carboxyl group in the said copolymer (A) into 1-20 mass%. When the content of the carboxyl group in the copolymer (A) is within the above range, water absorption due to the carboxyl group in the copolymer (A) is easily suppressed.

  The double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film of the present invention is bonded to an indium tin oxide film with a 2 kg roller in a temperature of 23 ° C. and a relative humidity of 50% RH in one reciprocation for one hour. The 180 ° peel adhesion at 300 mm / min after standing is preferably 5 to 15 N / 20 mm for the indium tin oxide film. Within the above range, it is easy to suppress peeling from the end face in fixing the transparent conductive film, and the double-sided pressure-sensitive adhesive sheet can be peeled off in a poorly bonded product in the manufacturing process.

  The thickness of the double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film of the present invention may be appropriately selected depending on the mode of use, but is preferably 5 to 200 μm. Especially, when adhering to a smooth surface, it is easy to make a touch panel apparatus thin by adjusting to 10-100 micrometers. Moreover, when sticking on the surface which has a level | step difference or an unevenness | corrugation, it is preferable that the thickness of an adhesive layer shall be 20 micrometers or more, and it is especially preferable to set it as 25-150 micrometers.

  The pressure-sensitive adhesive sheet for fixing a transparent conductive film of the present invention can be prepared by a generally used method. For example, it can be produced by forming an adhesive layer on a film substrate or a release sheet. Specifically, the adhesive composition is directly applied to the base film and dried or cured / polymerized, or once applied on the release sheet and dried / cured / polymerized to form an adhesive layer. Similarly, it can be produced by a method of bonding to an adhesive layer or a base film prepared on a release sheet.

  It is preferable that the pressure-sensitive adhesive layer does not adhere to the end face of the release film after the punching process of the transparent conductive film fixing pressure-sensitive adhesive sheet of the present invention. If the pressure-sensitive adhesive layer does not adhere to the end face of the release film, the yield during processing tends to be improved.

  In order to prevent adhesion of the pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet to the end face of the release film, it is easy to achieve by adjusting the cohesive force, adhesiveness and the like of the pressure-sensitive adhesive layer to the optimum ranges. Specific examples of the method include use of a carboxyl group-containing monomer in the pressure-sensitive adhesive layer, adjustment of the gel fraction of the pressure-sensitive adhesive layer to the above range, and the like. Especially, it is preferable to use a carboxyl group-containing monomer for the pressure-sensitive adhesive layer that can easily provide cohesive force necessary for punching and adhesion necessary for fixing the transparent conductive film.

[Transparent conductive film laminate]
The transparent conductive film laminate of the present invention is a laminate in which the adhesive layer of the double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film is directly bonded to the conductive layer of the transparent conductive film to form a laminate of at least two layers. For example, a laminate (FIG. 1) composed of a transparent conductive film provided with a conductive layer on a base material and the above-mentioned double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film can be mentioned. Moreover, the laminated body (FIG. 2) by which the hard-coat layer was provided in the opposite surface of the conductive layer, and the laminated body by which the transparent conductive film which has a hard-coat layer on both surfaces of the said transparent conductive film fixing double-sided adhesive sheet ( FIG. 3) is also included. In order to prevent damage to the laminate, a laminate (FIGS. 2 and 3) provided with a hard coat layer is preferable.

  The transparent conductive film used for this invention should just have a conductive layer in the surface layer of at least one side, and can use the transparent conductive film by which the electrically conductive substance was provided in the surface layer of the transparent base material by vapor deposition or coating. Among these, a transparent conductive film having a conductive layer in which a conductive substance is formed by vapor deposition is preferable because it can be easily manufactured.

  The conductive material deposited or coated in the conductive layer of the transparent conductive film is not particularly limited, and specific examples include indium tin oxide, indium oxide, tin oxide, zinc oxide, cadmium oxide, gallium oxide, and titanium oxide. It is done. In particular, indium tin oxide having excellent transparency and conductivity is preferable.

  In the transparent conductive film, the substrate on which the conductive material is deposited or coated is not particularly limited, and examples thereof include glass and resin films.

  Examples of the resin film on which the transparent conductive material is deposited include, for example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene film, polypropylene film, cellophane, diacetyl cellulose film, triacetyl cellulose film, acetyl cellulose butyrate film, polychlorinated Vinyl film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyether ether ketone film, polyether sulfone film, polyetherimide film , Polyimide film, fluorine resin film, nylon film, It can be exemplified Lil resin film. Of these, polyethylene terephthalate having excellent transparency and durability is preferable.

  The transparency of the transparent conductive film is preferably such that the total light transmittance is 80% or more and the haze is 1.0% or less, the total light transmittance is 90% or more, and the haze is 0.5% or less. More preferred. When the transparency of the transparent conductive film is within the above range, the transparency of the display equipped with the touch panel device using the transparent conductive film is easily maintained.

  The thickness of the transparent conductive film laminate is preferably 0.1 mm to 2.0 mm. Within the above range, it is easy to make the touch panel device thin.

In the transparent conductive film laminate, the increase rate of the electrical resistance value of the conductive film layer represented by the following formula is preferably 20% or less after being left for 500 hours at 60 ° C. and 90% RH. Within the above range, the touch panel device manufactured using the transparent conductive film laminate operates normally.
Rate of increase in electric resistance value of conductive film layer (%) = [(electric resistance value after standing at 60 ° C., 90% RH for 500 hours) − (initial electric resistance value)] / (initial electric resistance value) × 100

[Touch panel device]
The touch panel device of the present invention is characterized by having a transparent conductive film laminate formed by bonding the double-sided pressure-sensitive adhesive sheet to a transparent conductive film. The configuration of the touch panel device of the present invention is not particularly limited, but is preferably a configuration of a capacitive touch panel.

  As a preferred configuration example of the touch panel device of the present invention, a transparent conductive film laminate in which a transparent conductive film is provided on one side of a double-sided pressure-sensitive adhesive sheet is provided in two layers between a display panel (transparent panel) and an image display module. The capacitive type touch panel device (FIG. 4) can be exemplified. Of the two transparent conductive films with pressure-sensitive adhesive layers, at least one layer may be the transparent conductive film laminate of the present invention, and the transparent conductive film with pressure-sensitive adhesive layer on the image display module side is transparent of the present invention. The structure which is an electrically conductive film laminated body, or the structure where all the two transparent conductive films with an adhesive layer are the transparent electrically conductive film laminated body of the said invention can be used as a preferable structure. As another preferred configuration example, a transparent conductive film laminate in which a transparent conductive film is provided on both sides of a double-sided pressure-sensitive adhesive sheet is fixed between a display panel and an image display module with a fixing tape or a fixing adhesive. A capacitive touch panel device (FIG. 5) can be exemplified. In the said structure, since a touch panel apparatus can be manufactured by fixing a display panel, a transparent conductive film laminated body, and an image display module using a fixing tape or a fixing adhesive, an assembly process becomes easy.

  The protective panel of the touch panel device of the present invention is not particularly limited, and examples thereof include (meth) acrylic resin, polycarbonate resin, glass, and polyethylene terephthalate resin. Of these, a (meth) acrylic resin excellent in transparency and lightness is preferable.

  The display panel of the touch panel device of the present invention may have a decorative portion. Specific examples of the decorative part include characters and figures visually recognized around the image display part of the portable electronic terminal, or a black or white background provided on the back face thereof. These decorative portions are preferably provided in order to impart designability to the portable electronic terminal.

  The thickness of the touch panel device excluding the image display module is preferably 0.3 mm to 3.0 mm. Within the above range, the electronic device in which the touch panel device is incorporated can be easily made thin.

  In addition, when making the transparent conductive film with an adhesive layer by the side of an image display module into the transparent conductive film laminated body of the said invention, the thickness of the double-sided adhesive sheet of the said transparent conductive film laminated body shall be 5-200 micrometers. Is preferable, and 10 to 100 μm is particularly preferable. In addition, when the transparent conductive film with the pressure-sensitive adhesive layer on the side to be bonded to the display panel is used as the transparent conductive film laminate of the present invention, the thickness of the double-sided pressure-sensitive adhesive sheet is provided when a decorative part is provided on the display panel. Is preferably 25 to 200 μm, and more preferably 25 to 150 μm. Within the above range, the double-sided PSA sheet easily follows the decorative part of the display panel.

  The image display module used for the touch panel device is not particularly limited, and an LCD module or an organic EL module usually used for a small electronic terminal can be used.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

[Preparation of acrylic copolymer]
<Acrylic copolymer (1)>
Preparation of acrylic copolymer In a reaction vessel equipped with a stirrer, cold flow cooler, thermometer, dropping funnel and nitrogen gas inlet, 91.5 parts by weight of n-butyl acrylate, 0.5 parts by weight of 2-hydroxyethyl acrylate, 8.0 parts by weight of acrylic acid and 0.2 parts of 2,2′-azobisisobutylnitrile as a polymerization initiator are dissolved in 100 parts by weight of ethyl acetate, and after substitution with nitrogen, polymerization is carried out at 80 ° C. for 8 hours to obtain a weight average. An acrylic copolymer (1) having a molecular weight of 800,000 was obtained.
<Acrylic copolymer (2)>
Preparation of acrylic copolymer In a reaction vessel equipped with a stirrer, cold flow cooler, thermometer, dropping funnel and nitrogen gas inlet, 81.5 parts by weight of n-butyl acrylate, 10.0 parts by weight of silohexyl methacrylate, 2- After dissolving 0.5 parts by weight of hydroxyethyl acrylate, 8.0 parts by weight of acrylic acid and 0.2 part of 2,2′-azobisisobutylnitrile as a polymerization initiator in 100 parts by weight of ethyl acetate, 80% after substitution with nitrogen, Polymerization was performed at 0 ° C. for 8 hours to obtain an acrylic copolymer (2) having a weight average molecular weight of 850,000.

<Acrylic copolymer (3)>
Acrylic copolymer (3) having a weight average molecular weight of 800,000 in the same manner as acrylic acid copolymer (1) except that 95.5 parts by weight of n-butyl acrylate and 4.0 parts by weight of acrylic acid are used. Got.

<Acrylic copolymer (4)>
Preparation of acrylic copolymer In a reaction vessel equipped with a stirrer, cold flow cooler, thermometer, dropping funnel and nitrogen gas inlet, 96.5 parts by weight of n-butyl acrylate, 0.5 parts by weight of 2-hydroxyethyl acrylate, Dissolve 3.0 parts by weight of dimethylaminoethyl methacrylate and 0.2 part of 2,2′-azobisisobutylnitrile as a polymerization initiator in 100 parts by weight of ethyl acetate, and after purging with nitrogen, polymerize at 80 ° C. for 8 hours. An acrylic copolymer (4) having a weight average molecular weight of 300,000 was obtained.

<Acrylic copolymer (5)>
Preparation of acrylic copolymer In a reaction vessel equipped with a stirrer, cold flow cooler, thermometer, dropping funnel and nitrogen gas inlet, 95.0 parts by weight of methyl methacrylate, 5.0 parts by weight of dimethylaminoethyl methacrylate and a polymerization initiator As follows, 1.0 part by weight of 2,2′-azobisisobutylnitrile is dissolved in 100 parts by weight of ethyl acetate, and after substitution with nitrogen, polymerization is carried out at 80 ° C. for 8 hours to give a methacrylic copolymer having a weight average molecular weight of 20,000 (5 )

<Adhesive A>
20 parts by weight of the acrylic copolymer (5) was added to 100 parts by weight of the acrylic copolymer (1), and diluted with ethyl acetate to obtain an adhesive A having a resin solid content of 30%. In addition, the equivalent ratio of the carboxyl group of the acrylic copolymer (1) and the nitrogen atom of the acrylic copolymer (5) is 1: 0.0625.

<Adhesive B>
20 parts by weight of the acrylic copolymer (5) was added to 100 parts by weight of the acrylic copolymer (2), and diluted with ethyl acetate to obtain an adhesive B having a resin solid content of 30%. In addition, the equivalent ratio of the carboxyl group of the acrylic copolymer (2) and the nitrogen atom of the acrylic copolymer (5) is 1: 0.0625.

<Adhesive C>
20 parts by weight of the acrylic copolymer (5) was added to 100 parts by weight of the acrylic copolymer (3), and diluted with ethyl acetate to obtain an adhesive C having a resin solid content of 30%. In addition, the equivalent ratio of the carboxyl group of the acrylic copolymer (3) and the nitrogen atom of the acrylic copolymer (5) is 1: 0.125.

<Adhesive D>
100 parts by weight of the acrylic copolymer (1) was diluted with ethyl acetate to obtain a pressure-sensitive adhesive D having a resin solid content of 30%.

<Adhesive E>
100 parts by weight of the acrylic copolymer (4) was diluted with ethyl acetate to obtain an adhesive E having a resin solid content of 30%.

<Adhesive F>
5 parts by weight of a metal deactivator BTZM (manufactured by Kyodo Chemical Co., Ltd.) was added to 100 parts by weight of the acrylic copolymer (1), and diluted with ethyl acetate to obtain an adhesive F having a resin solid content of 30%. .

Example 1
0.7 parts by weight of an isocyanate-based crosslinking agent (Nihon Polyurethane Coronate L-45, solid content 45%) was added to 100 parts by weight of the above-mentioned pressure-sensitive adhesive A, and the resulting mixture was stirred for 15 minutes. The polyester film (hereinafter referred to as # 75 release film) was coated so that the thickness after drying was 25 μm, and dried at 75 ° C. for 5 minutes. The obtained pressure-sensitive adhesive sheet and a 38 μm-thick polyester film (hereinafter referred to as # 38 release film) having one surface peel-treated with a silicone compound were bonded together. Thereafter, it was aged at 23 ° C. for 5 days to obtain a substrate-less pressure-sensitive adhesive sheet having a thickness of 25 μm and a gel fraction of 70%.

(Example 2)
A pressure-sensitive adhesive sheet having a gel fraction of 75% was obtained in the same manner as in Example 1 except that 100 parts by weight of the pressure-sensitive adhesive A was changed to 100 parts by weight of the pressure-sensitive adhesive B.

(Example 3)
An adhesive sheet having a gel fraction of 71% was obtained in the same manner as in Example 1 except that 100 parts by weight of the adhesive A was changed to 100 parts by weight of the adhesive C.

(Comparative Example 1)
A pressure-sensitive adhesive sheet having a gel fraction of 85% was obtained in the same manner as in Example 1 except that 100 parts by weight of the pressure-sensitive adhesive A was changed to 100 parts by weight of the pressure-sensitive adhesive D.

(Comparative Example 2)
A pressure-sensitive adhesive sheet having a gel fraction of 80% was obtained in the same manner as in Example 1 except that 100 parts by weight of the pressure-sensitive adhesive A was changed to 100 parts by weight of the pressure-sensitive adhesive E.

(Comparative Example 3)
A pressure-sensitive adhesive sheet having a gel fraction of 70% was obtained in the same manner as in Example 1 except that 100 parts by weight of the pressure-sensitive adhesive A was changed to 100 parts by weight of the pressure-sensitive adhesive F.

(Measurement of electrical resistance of indium tin oxide film)
After bonding to a PET film (100 μm) on one side of the double-sided PSA sheet, it is cut to 50 mm × 50 mm and bonded to the indium tin oxide film surface of the 100 mm × 100 mm indium tin oxide-deposited PET film. The electrical resistance value measuring device “Lorestar GP” manufactured by Mitsubishi Chemical Corporation was used at both ends of the bonded adhesive sheet, and the initial electrical resistance value (R1) was measured. The indium tin oxide-deposited PET film to which the adhesive sheet was bonded was left at 90 ° C. for 500 hours and left at 23 ° C. and 50% RH for 1 hour. The resistance value (R2) was measured. The increase rate of the electric resistance value of the indium tin oxide film was calculated by the following formula.
Increasing rate of electric resistance value of indium tin oxide film (%) = ((R2-R1) / R1) × 100

(Total light transmittance and haze measurement)
After the pressure-sensitive adhesive sheet was allowed to stand for 100 hours under conditions of 60 ° C. and 90% RH, a test sample was prepared by laminating in the order of PET film and glass. Using the “HR-100 Model” manufactured by Murakami Color Research Laboratory Co., Ltd., the total light transmittance and haze (%) of the adjusted sample were measured.

(Color difference measurement)
The pressure-sensitive adhesive sheet was bonded in the order of PET film and glass to prepare a test sample. Using a “spectral colorimeter CM3500d” manufactured by Konica Minolta Sensing Co., Ltd., L1 ^* , a1 ^* , and b1 ^* of the adjusted sample were measured. Thereafter, the adjusted sample was left at 85 ° C. for 100 hours, and L2 ^* , a2 ^* , and b2 ^* were measured. The color difference ΔE ^* ab was calculated from the following formula, and the discoloration of the pressure-sensitive adhesive sheet was evaluated.
Color difference ΔE ^* ab = [(L2 ^* −L1 ^* ) ² + (a2 ^* −a1 ^* ) ² + (b2 ^* −b1 ^* ) ² ] ^1/2
○: ΔE ^* ab 0-0.5
Δ: ΔE ^* ab 0.5 to 1.5
×: ΔE ^* ab 1.5 or more

(Measurement of water absorption)
A 100 mm × 100 mm double-sided PSA sheet is allowed to stand at 60 ° C. and 90% RH for 100 hours, and then immediately peeled off the double-sided PSA sheet and bonded to a 150 mm × 150 mm aluminum foil and weighed (this) Weight is W1). The other release film of the double-sided PSA sheet is peeled off and dried at 105 ° C. for 2 hours, and then weighed (this weight is designated as W2). The water absorption rate of the double-sided PSA sheet was calculated by the following formula.
Water absorption of double-sided PSA sheet (%) = (W1−W2) / W2 × 100

(Evaluation of peeling resistance)
After adhering the PET film surface of a 45 mm x 35 mm PET film with a hard coat layer and 50 mm x 40 mm glass with an adhesive sheet, leave it at 85 ° C for 500 hours and visually peel off the PET film with a hard coat. evaluated.
○: No peeling ×: There is peeling

  As described above, the double-sided pressure-sensitive adhesive sheets of Examples 1 to 3 were subjected to a high humidity environment test even when a carboxyl group-containing (meth) acrylic acid ester copolymer capable of realizing suitable peeling resistance was used. The increase rate of the electrical resistance value of the conductive layer of the transparent conductive film can be suitably suppressed, and the visibility is not deteriorated due to discoloration. Moreover, the transparency and haze required when used for an image display device such as a touch panel were also suitable. On the other hand, in the structure of the comparative example 1 which does not use a nitrogen atom containing (meth) acrylic acid ester copolymer, the electrical resistance value was significantly increased by a high humidity environment test. Further, the configuration of Comparative Example 2 that does not use a carboxyl group-containing (meth) acrylic acid ester copolymer cannot realize suitable peeling resistance, and the configuration of Comparative Example 3 that uses a conventional metal corrosion inhibitor is visually recognized by discoloration. Sexual deterioration occurred.

It is a conceptual diagram which shows an example of the transparent conductive film laminated body by which the double-sided adhesive sheet for transparent conductive film fixation of this invention and the transparent conductive film were laminated | stacked. It is a conceptual diagram which shows an example of the transparent conductive film laminated body by which the double-sided adhesive sheet for transparent conductive film fixation of this invention and the transparent conductive film were laminated | stacked. It is a conceptual diagram which shows an example of the transparent conductive film laminated body by which the double-sided adhesive sheet for transparent conductive film fixation of this invention and the transparent conductive film were laminated | stacked. It is a conceptual diagram of the electrostatic capacitance type touch panel device using the transparent conductive film laminated body by which the double-sided adhesive sheet for transparent conductive film fixation of this invention and the transparent conductive film were laminated | stacked. It is a conceptual diagram of the electrostatic capacitance type touch panel device using the transparent conductive film laminated body by which the double-sided adhesive sheet for transparent conductive film fixation of this invention and the transparent conductive film were laminated | stacked.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent conductive film laminated body 2 Double-sided adhesive sheet for transparent conductive film fixation 3 Conductive layer 4 Transparent base material 5 Hard-coat layer 6 Protection panel 7 Decoration layer 8 Transparent conductive film with an adhesive layer 9 Fixing tape 10 Image display module

Claims (7)

A double-sided pressure-sensitive adhesive sheet to be bonded to a conductive layer surface of a transparent conductive film, wherein the pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet comprises a carboxyl group-containing (meth) acrylic acid ester copolymer (A) and a nitrogen atom-containing (meth) acrylic. It comprises a pressure-sensitive adhesive composition having an acid ester copolymer (B), a carboxyl group-containing (meth) acrylic acid ester copolymer (A) in the pressure-sensitive adhesive composition, and a nitrogen atom-containing (meta ) A double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film, wherein the equivalent ratio of the acrylic ester copolymer (B) to the nitrogen atom is from 1: 0.05 to 1: 0.5. The carboxyl group-containing (meth) acrylic acid ester copolymer (A) has a weight average molecular weight of 500,000 to 2,000,000, and the nitrogen atom-containing (meth) acrylic acid ester copolymer (B) has a weight average molecular weight of 5000. The double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film according to claim 1, which is 100,000 to 100,000. The transparent according to claim 1 or 2, wherein the total light transmittance measured after standing at 60 ° C and 90% RH for 100 hours is 90% or more and the haze is 1.0% or less. Double-sided pressure-sensitive adhesive sheet for fixing conductive films. The double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film according to any one of claims 1 to 3, wherein the water absorption after standing at 60 ° C and 90% RH for 100 hours is 2.0% or less. The nitrogen atom-containing (meth) acrylic acid ester copolymer (B) is a monomer component comprising a (meth) acrylic acid ester monomer having 1 to 8 carbon atoms and a nitrogen atom-containing copolymerizable monomer. The nitrogen atom-containing copolymerizable monomer is an amino group-containing monomer, an amide group-containing monomer, a nitrogen-based heterocyclic ring-containing monomer, a cyano group-containing monomer, and an imide group-containing monomer. The double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film according to any one of claims 1 to 4, which is at least one of the monomers. A transparent conductive film laminate in which the double-sided pressure-sensitive adhesive sheet for fixing a transparent conductive film according to claim 1 is bonded to a transparent conductive film, and the transparent conductive film after being left for 500 hours under conditions of 60 ° C and 90% RH The increase rate of the electrical resistance value is 20% or less from the electrical resistance value at the initial stage of application. A touch panel device comprising the transparent conductive film laminate according to claim 6.

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