JP2015016653A - Adhesive layer for transparent conductive film, transparent conductive film having adhesive layer and touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive layer for a transparent conductive film configured to be applied to a functional layer of a transparent conductive film having a transparent conductive thin film on one face of a transparent plastic film substrate and the functional layer on the other face, the adhesive layer having high sebum resistance, humidification white turbidness resistance, and low dielectric constant.SOLUTION: An adhesive layer for a transparent conductive film is produced from an adhesive agent including a (meth)acrylic polymer obtained by polymerizing monomer components containing monofunctional monomer components including: 30-75 wt.% of alkyl(meth) acrylate having an alkyl group having 10-24 carbon atoms at an ester end; and 20-50 wt.% of a cyclic nitrogen-containing monomer.

Description

  The present invention is a pressure-sensitive adhesive layer for a transparent conductive film, which is applied to the functional layer of a transparent conductive film having a transparent conductive thin film on one side of a transparent plastic film substrate and a functional layer on the other side. Further, the present invention relates to a pressure-sensitive adhesive layer for a transparent conductive film that has high sebum resistance and humid clouding resistance and can achieve a low dielectric constant.

  Moreover, this invention has the said transparent adhesive film adhesive layer for the said functional layer of the transparent conductive film which has a transparent conductive thin film on one side of a transparent plastic film base material, and a functional layer on the other side. It is related with the transparent conductive film with the adhesive layer provided. The pressure-sensitive adhesive layer for a transparent conductive film or the transparent conductive film with a pressure-sensitive adhesive layer of the present invention is suitable for use in the production of input devices such as an optical method, an ultrasonic method, a capacitance method, a resistance film method, etc. Can be used. In particular, it is suitably used for a capacitive touch panel.

  Moreover, the transparent conductive film with an adhesive layer of this invention is used for the transparent electrode in a touch panel etc., after an appropriate processing process is made. In particular, the transparent conductive film with an adhesive layer is suitably used for an electrode substrate of an input device of a capacitive touch panel by patterning a transparent conductive thin film.

  In recent years, an input device using a combination of an image display device such as a mobile phone or a portable music player and a touch panel has become widespread. In particular, capacitive touch panels are rapidly spreading due to their functionality.

  Currently, many transparent conductive films used for touch panels are known in which a transparent conductive thin film (ITO film) is laminated on a transparent plastic film substrate or glass. A transparent conductive film is laminated | stacked on another member through an adhesive layer. Various types of pressure-sensitive adhesive layers have been proposed (see Patent Documents 1 to 4).

  When the transparent conductive film is used for an electrode substrate of a capacitive touch panel, a film obtained by patterning the transparent conductive thin film is used. A transparent conductive film having such a patterned transparent conductive thin film is used by being laminated with an adhesive layer together with other transparent conductive films and the like. These transparent conductive films are suitably used for multi-touch type input devices that can be operated simultaneously with two or more fingers. In other words, the capacitive touch panel has a mechanism for sensing when the output signal of the position changes when the touch panel is touched with a finger or the like, and the amount of change of the signal exceeds a certain threshold.

  As described above, the dielectric constant of the member and film constituting the touch panel is an important numerical value because it relates to the response of the touch panel. On the other hand, with the spread of touch panels in recent years, higher performance is required for touch panels, and high performance is also required for transparent conductive films and pressure-sensitive adhesive layers that are constituent members, and thinning is one of them. is there. However, there is a problem that the designed capacitance value changes if the pressure-sensitive adhesive layer is simply thinned. In order to reduce the thickness of the pressure-sensitive adhesive layer without changing the value of the capacitance value, it is required to lower the dielectric constant of the pressure-sensitive adhesive layer. In addition, in order to improve visibility, an air layer of glass with printing or a film and an optical film or an air layer above the LCD may be filled with an adhesive layer, but on the other hand, If the dielectric constant is high, malfunction may occur. Also from the viewpoint of preventing such malfunction, the adhesive layer is required to have a low dielectric constant. Furthermore, the response speed and sensitivity of the touch panel are expected to be improved by reducing the dielectric constant of the adhesive layer. In addition, there is a problem that the adhesive layer becomes cloudy when a laminate obtained by laminating a transparent conductive film or glass via an adhesive layer is exposed to humidification conditions. It has been.

  It is described that the pressure-sensitive adhesive layer described in Patent Document 4 can improve the humid turbidity resistance by using a predetermined amount of a cyclic nitrogen-containing monomer as a monomer component constituting the (meth) acrylic polymer.

JP 2003-238915 A JP 2003-342542 A JP 2004-231723 A JP2013-082880A

  Moreover, since the said touch panel is used in the state which a bare hand always contacts, it is not avoided that the sebum of a hand transfers to a touch panel. The sebum transferred to the touch panel surface gradually moves to the pressure-sensitive adhesive layer inside the touch panel, and the pressure-sensitive adhesive layer swells due to sebum, and sebum resistance is required.

  However, conventionally, the swelling of the pressure-sensitive adhesive layer by sebum has not been sufficiently studied, and in Patent Documents 1 to 4, no investigation has been made on the swelling of the pressure-sensitive adhesive layer by sebum. Met.

  Moreover, although a transparent conductive film has a transparent conductive thin film on the single side | surface of a transparent plastic film base material, it may have functional layers, such as a hard-coat layer, on the other side.

  Therefore, the present invention has a transparent conductive film adhesive applied to the functional layer of a transparent conductive film having a transparent conductive thin film on one side of a transparent plastic film substrate and a functional layer on the other side. An object is to provide a pressure-sensitive adhesive layer having a sebum resistance, a high humidity resistance against cloudiness and a low dielectric constant.

  Moreover, this invention aims at providing the touchscreen which has the transparent conductive film with an adhesive layer which has the said adhesive layer for transparent conductive films, and also has the said transparent conductive film with an adhesive layer. To do.

  As a result of intensive studies to solve the above problems, the present inventors have found the following pressure-sensitive adhesive layer for transparent conductive film, and have completed the present invention.

That is, the present invention is a pressure-sensitive adhesive for transparent conductive film, which is applied to the functional layer of a transparent conductive film having a transparent conductive thin film on one side of a transparent plastic film substrate and a functional layer on the other side. Layer,
The pressure-sensitive adhesive layer includes a monofunctional monomer component containing 30 to 75% by weight of an alkyl (meth) acrylate having an alkyl group having 10 to 24 carbon atoms at an ester terminal and 20 to 50% by weight of a cyclic nitrogen-containing monomer. It is related with the adhesive layer for transparent conductive films characterized by including the (meth) acrylic-type polymer obtained by superposing | polymerizing a monomer component. The alkyl (meth) acrylate having an alkyl group having 10 to 24 carbon atoms at the ester end is preferably an alkyl group having a branched alkyl group. The alkyl (meth) acrylate having an alkyl group having 10 to 24 carbon atoms at the ester end is preferably alkyl methacrylate from the viewpoint of low dielectric constant, and is preferably alkyl acrylate from the viewpoint of productivity.

  In the transparent conductive film pressure-sensitive adhesive layer, the monofunctional monomer component may further contain 1% by weight or more of a hydroxyl group-containing monomer.

  In the transparent conductive film pressure-sensitive adhesive layer, the monofunctional monomer component further includes an alkyl (meth) acrylate having an alkyl group having 1 to 9 carbon atoms at the ester end and an alkyl having a cyclic alkyl group at the ester end ( At least one selected from (meth) acrylate can be contained in an amount of 0.5% by weight or more.

  In the transparent conductive film pressure-sensitive adhesive layer, the monomer component may further contain 3 parts by weight or less of a polyfunctional monomer with respect to 100 parts by weight of the monofunctional monomer component. The monofunctional monomer is a monomer having one polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group, and the polyfunctional monomer is a (meth) acryloyl group or A monomer having two or more polymerizable functional groups having an unsaturated double bond such as a vinyl group.

  The transparent conductive film pressure-sensitive adhesive layer preferably has a relative dielectric constant of 3.5 or less at a frequency of 100 kHz. Moreover, it is preferable that the gel fraction of the said adhesive layer for transparent conductive films is 20 to 98 weight%.

  Moreover, this invention has a transparent conductive thin film on the single side | surface of a transparent plastic film base material, The said one side of a transparent conductive film which has a functional layer on the other side is any one of Claims 1-6. It is related with the transparent conductive film with an adhesive layer provided with the adhesive layer for transparent conductive films as described in above.

  The present invention relates to a touch panel having at least one transparent conductive film with an adhesive layer.

  The (meth) acrylic polymer as the main component in the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer for transparent conductive film of the present invention is a cyclic nitrogen containing alkyl (meth) acrylate having a long-chain alkyl group and a cyclic nitrogen-containing monomer. It is obtained by polymerizing the monomer component containing the containing monomer. According to the pressure-sensitive adhesive of the present invention, a pressure-sensitive adhesive layer having a low dielectric constant and excellent in humid turbidity resistance is realized by the action of the long-chain alkyl group and the cyclic structure having a nitrogen atom of the cyclic nitrogen-containing monomer. It is possible to satisfy the adhesion performance. Moreover, even when the air layer is filled with an adhesive layer, malfunction can be prevented because the adhesive layer has a low dielectric constant.

  In order to lower the dielectric constant, it is considered that the molecular dipole moment is reduced and the molar volume is increased from the Clausius-Mossotti equation. The alkyl (meth) acrylate according to the main monomer unit constituting the (meth) acrylic polymer as the main component in the pressure-sensitive adhesive of the present invention has a long-chain alkyl group, and the monomer unit for copolymerization is a nitrogen atom. It is considered that the dielectric constant decreases because it has an annular structure having Further, it is considered that the humidified cloudiness resistance can be satisfied by the cohesiveness and hydrophilic action in the cyclic structure having a nitrogen atom.

  For example, the pressure-sensitive adhesive layer of the present invention satisfies the low dielectric constant of 3.5 or less at 100 kHz, thereby reducing the thickness of the pressure-sensitive adhesive layer of the present invention and using it for a capacitive touch panel. Even when used for adhesive layers applied to conductive films, it can be applied without changing the numerical value of the capacitance value designed with the capacitive touch panel, and it must satisfy the humid cloudiness resistance. Can do.

  Moreover, the monofunctional monomer component which concerns on the (meth) acrylic-type polymer in the adhesive of this invention contains the cyclic | annular nitrogen-containing monomer by the predetermined ratio (20-50 weight%), and cyclic | annular nitrogen-containing monomer is contained in this ratio. By containing, it is possible to realize a pressure-sensitive adhesive layer having good anti-humidity cloudiness and sebum resistance. In particular, the pressure-sensitive adhesive layer of the present invention can satisfy humidification cloudiness resistance even under heating conditions. For example, a transparent conductive film with a pressure-sensitive adhesive layer in which a pressure-sensitive adhesive layer is laminated on a functional layer of a transparent conductive film. The transparent conductive thin film can be crystallized in the form of a film.

It is a schematic sectional drawing which shows an example of the transparent conductive film with an adhesive layer to which the adhesive layer for transparent conductive films of this invention is applied. It is a figure which shows an example of the capacitive touch panel with which the adhesive layer for transparent conductive films of this invention is applied in relation to a transparent conductive film. It is a schematic sectional drawing of the test piece used by each test of humidification cloudiness resistance.

  The pressure-sensitive adhesive layer for a transparent conductive film of the present invention will be described below with reference to the drawings in the embodiment of the transparent conductive film with a pressure-sensitive adhesive layer.

  FIG. 1 is a cross-sectional view showing an embodiment in which the transparent conductive film pressure-sensitive adhesive layer 3 of the present invention is provided on a transparent conductive film 4. A transparent conductive film 4 shown in FIG. 1 has a transparent conductive thin film 6 on one surface of a transparent plastic film substrate 7. Further, the functional layer 8 is provided on the other side of the transparent plastic film substrate 7, that is, on the side opposite to the transparent conductive thin film 6. The adhesive layer 3 for transparent conductive film is provided on the functional layer 8.

  Although it does not restrict | limit especially as said transparent plastic film base material, The various plastic film which has transparency is used. The plastic film is formed of a single layer film. For example, the materials include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins. , Polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl alcohol resin, polyarylate resin, polyphenylene sulfide resin, and the like. Of these, polyester resins, polyimide resins and polyethersulfone resins are particularly preferable. The thickness of the film substrate is preferably 15 to 200 μm.

  The film base material is subjected to etching treatment or undercoating treatment such as sputtering, corona discharge, flame, ultraviolet irradiation, electron beam irradiation, chemical conversion, oxidation, etc. on the surface in advance, and a transparent conductive thin film or undercoat provided thereon You may make it improve the adhesiveness with respect to the said film base material of a layer. In addition, before providing the transparent conductive thin film or the undercoat layer, dust may be removed and cleaned by solvent cleaning or ultrasonic cleaning as necessary.

  The constituent material of the transparent conductive thin film is not particularly limited, and is selected from the group consisting of indium, tin, zinc, gallium, antimony, titanium, silicon, zirconium, magnesium, aluminum, gold, silver, copper, palladium, tungsten, cadmium. A metal oxide of at least one selected metal is used. The metal oxide may further contain a metal atom shown in the above group, if necessary. For example, although not particularly limited, for example, ITO (indium tin oxide), ZnO, SnO, CTO (cadmium tin oxide) and the like are preferably used, and ITO is particularly preferably used. As ITO, it is preferable to contain 80 to 99 weight% of indium oxide and 1 to 20 weight% of tin oxide. Although the thickness of a transparent conductive thin film is not specifically limited, It is about 10-200 nm, From the viewpoint of a thin film, it is more preferable that it is 15-40 nm, and it is more preferable that it is 20-30 nm.

  In addition, although not shown in FIG. 1, a transparent conductive thin film can be provided in a transparent plastic film base material through an undercoat layer. A plurality of undercoat layers can be provided. An oligomer migration preventing layer can be provided between the transparent plastic film substrate and the pressure-sensitive adhesive layer.

The undercoat layer can be formed of an inorganic material, an organic material, or a mixture of an inorganic material and an organic material. For example, NaF (1.3), Na ₃ AlF ₆ (1.35), LiF (1.36), MgF ₂ (1.38), CaF ₂ (1.4), BaF ₂ (1. 3), inorganic substances such as SiO ₂ (1.46), LaF ₃ (1.55), CeF ₃ (1.63), Al ₂ O ₃ (1.63) [the values in parentheses for the above materials are Is the refractive index of light. Of these, SiO ₂ , MgF ₂ , A1 ₂ O _{3 and the} like are preferably used. In particular, SiO ₂ is suitable. In addition to the above, a composite oxide containing about 10 to 40 parts by weight of cerium oxide and about 0 to 20 parts by weight of tin oxide with respect to indium oxide can be used.

  Examples of organic substances include acrylic resins, urethane resins, melamine resins, alkyd resins, siloxane polymers, and organic silane condensates. At least one of these organic substances is used. In particular, as the organic substance, it is desirable to use a thermosetting resin made of a mixture of a melamine resin, an alkyd resin, and an organosilane condensate.

  The thickness of the undercoat layer is not particularly limited, but is usually about 1 to 300 nm, preferably 5 to 300 nm, from the viewpoint of optical design and the effect of preventing oligomer generation from the film substrate. .

  As the functional layer, for example, an antiglare treatment (AG) layer or an antireflection (AR) layer for the purpose of improving visibility can be provided. The constituent material of the antiglare layer is not particularly limited, and for example, an ionizing radiation curable resin, a thermosetting resin, a thermoplastic resin, or the like can be used. The thickness of the antiglare treatment layer is preferably 0.1 to 30 μm. As the antireflection layer, titanium oxide, zirconium oxide, silicon oxide, magnesium fluoride, or the like is used. The antireflection layer can be provided with a plurality of layers.

  Moreover, a hard coat (HC) layer can be provided as a functional layer. As a material for forming the hard coat layer, for example, a cured film made of a curable resin such as a melamine resin, a urethane resin, an alkyd resin, an acrylic resin, or a silicone resin is preferably used. The thickness of the hard coat layer is preferably 0.1 to 30 μm. The thickness is preferably 0.1 μm or more for imparting hardness. Further, the antiglare treatment layer and the antireflection layer can be provided on the hard coat layer.

  The pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer for a transparent conductive film of the present invention is 30 to 75% by weight of an alkyl (meth) acrylate having an alkyl group having 10 to 24 carbon atoms at the ester terminal and 20 cyclic nitrogen-containing monomers. (Meth) acrylic-type polymer obtained by superposing | polymerizing the monomer component containing the monofunctional monomer component containing -50weight% is included. Alkyl (meth) acrylate refers to alkyl acrylate and / or alkyl methacrylate, and (meth) in the present invention has the same meaning.

  The Tg of the homopolymer related to the alkyl (meth) acrylate having an alkyl group having 10 to 24 carbon atoms at the ester end is preferably -80 to 0 ° C, more preferably -70 to -10 ° C, It is preferably −60 to −10 ° C. When the Tg of the homopolymer is less than −80 ° C., the elastic modulus of the pressure-sensitive adhesive at normal temperature may be excessively lowered, and when it exceeds 0 ° C., the adhesive force may be decreased. The Tg of the homopolymer is a value measured by TG-DTA. In addition, the alkyl group has 10 to 24 carbon atoms from the viewpoint of satisfying a low dielectric constant and an appropriate elastic modulus, but an alkyl having a preferable alkyl group depending on the method for producing a (meth) acrylic polymer ( A (meth) acrylate can be selected. The alkyl group preferably has 12 to 24 carbon atoms, more preferably 12 to 22 carbon atoms, further 12 to 20 carbon atoms, further 14 to 20 carbon atoms, and more preferably 14 to 18 carbon atoms. In addition, even if Tg of the homopolymer based on the alkyl (meth) acrylate is −80 to 0 ° C., the effect of lowering the dielectric constant of the pressure-sensitive adhesive layer is not great if the carbon number is 9 or less.

  In the alkyl (meth) acrylate, the alkyl group having 10 to 24 carbon atoms may be either linear or branched, but from the viewpoint of the effect of reducing the dielectric constant of the pressure-sensitive adhesive layer, Alkyl groups are preferred over linear alkyl groups. It is considered that the long-chain alkyl group of the alkyl (meth) acrylate has a molar volume that is increased due to the branching of the alkyl group, the dipole moment is decreased, and a pressure-sensitive adhesive layer having a balance between the two is obtained.

  Examples of the alkyl (meth) acrylate having a branched alkyl group having 10 to 24 carbon atoms at the ester terminal include, for example, isodecyl acrylate (carbon number 10, homopolymer Tg = −60 ° C., hereinafter simply abbreviated as Tg). ), Isodecyl methacrylate (carbon number 10, Tg = −41 ° C.), isomistyryl acrylate (carbon number 14, Tg = −56 ° C.), isocetyl acrylate (2-hexyl-decyl acrylate), isostearyl acrylate (carbon number) 18, Tg = −18 ° C., in the case of chemical formula 1 below), isostearyl acrylate (structural formula different from chemical formula 1 below, NK-ISA manufactured by Shin-Nakamura Chemical Co., Ltd.), 2-propylheptyl acrylate, isoun Decyl acrylate, isododecyl acrylate, isotridecyl acrylate, isopen Examples include tadecyl acrylate, isohexadecyl acrylate, isoheptadecyl acrylate, isononadecyl acrylate, isoheneicosyl acrylate, isodocosyl acrylate, and the methacrylate monomers exemplified above. These can be used alone or in combination of two or more.

Among the alkyl groups having 10 to 24 carbon atoms, those having a t-butyl group, in particular, have a pressure-sensitive adhesive layer having a balance between the two because the molar volume increases and the dipole moment decreases. It is preferable at the point considered to be obtained. As an alkyl (meth) acrylate having a t-butyl group and having an alkyl group having 10 to 24 carbon atoms, an isostearyl acrylate having 18 carbon atoms represented by the following formula (ISTA made by Osaka Organic Chemical Co., Ltd.) , NK-S1800A manufactured by Shin-Nakamura Chemical Co., Ltd.).

  In addition, as an alkyl (meth) acrylate having an alkyl group having 10 to 24 carbon atoms at the ester end, an alkyl methacrylate is more adhesive than an alkyl acrylate due to an increase in molar volume and a decrease in dipole moment. This is preferable in terms of the effect of lowering the dielectric constant. In the case of the alkyl methacrylate, even when the long-chain alkyl group is a linear alkyl group, the molar volume is increased, the dipole moment is decreased, and an adhesive layer having a balance between the two is obtained. On the other hand, alkyl acrylate is more preferable than alkyl methacrylate because it has better compatibility with cyclic nitrogen-containing monomers, and a (meth) acrylic polymer having good transparency can be obtained. This is preferable in that the polymerization time for producing the polymer can be shortened to improve productivity. In particular, when a (meth) acrylic polymer is produced by radiation polymerization, an alkyl acrylate is preferable.

  In the present invention, the alkyl (meth) acrylate having an alkyl group having 10 to 24 carbon atoms at the ester terminal is 30 to 75% by weight based on the total amount of the monofunctional monomer component forming the (meth) acrylic polymer. It is preferably 32 to 72% by weight, more preferably 33 to 70% by weight. Use of 30% by weight or more is preferable from the viewpoint of reducing the dielectric constant, and use of 75% by weight or less is preferable from the viewpoint of maintaining the adhesive strength.

  As the cyclic nitrogen-containing monomer, those having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a cyclic nitrogen structure can be used without particular limitation. The cyclic nitrogen structure preferably has a nitrogen atom in the cyclic structure. Examples of cyclic nitrogen-containing monomers include lactam vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinyl Examples thereof include vinyl monomers having a nitrogen-containing heterocyclic ring such as imidazole, vinyl oxazole and vinyl morpholine. Moreover, the (meth) acryl monomer containing heterocyclic rings, such as a morpholine ring, a piperidine ring, a pyrrolidine ring, a piperazine ring, is mentioned. Specific examples include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine and the like. Among the cyclic nitrogen-containing monomers, lactam vinyl monomers are preferable from the viewpoint of dielectric constant and cohesiveness.

  In the present invention, the cyclic nitrogen-containing monomer is 20 to 50% by weight, preferably 25 to 40% by weight, more preferably 25%, based on the total amount of the monofunctional monomer component forming the (meth) acrylic polymer. -35% by weight. It is preferable for the ratio of the cyclic nitrogen-containing monomer to be 20% by weight or more because all of the low dielectric constant, excellent sebum resistance, and excellent white turbidity resistance can be satisfied. In addition, when the proportion of the cyclic nitrogen-containing monomer exceeds 50% by weight, the elastic modulus of the (meth) acrylic polymer tends to be high, and the adhesive property tends to be reduced. This is not preferable because of the tendency to

  The monomer component forming the (meth) acrylic polymer of the present invention can contain a hydroxyl group-containing monomer as a monofunctional monomer component. As the hydroxyl group-containing monomer, a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a hydroxyl group can be used without particular limitation. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl ( Hydroxyalkyl (meth) acrylates such as (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate and the like; And hydroxyalkylcycloalkane (meth) acrylates such as 4-hydroxymethylcyclohexyl) methyl (meth) acrylate. Other examples include hydroxyethyl (meth) acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, and the like. These can be used alone or in combination. Of these, hydroxyalkyl (meth) acrylate is preferred.

  In the present invention, the hydroxyl group-containing monomer is preferably 1% by weight or more from the viewpoint of enhancing adhesive force and cohesive force with respect to the total amount of the monofunctional monomer component forming the (meth) acrylic polymer, Further, it is preferably 2% by weight or more, and more preferably 3% by weight or more. On the other hand, if the amount of the hydroxyl group-containing monomer is too large, the pressure-sensitive adhesive layer becomes hard and the adhesive strength may decrease, and the viscosity of the pressure-sensitive adhesive may become too high or gel. The hydroxyl group-containing monomer is preferably 30% by weight or less, more preferably 27% by weight or less, and further 25% by weight with respect to the total amount of the monofunctional monomer component forming the (meth) acrylic polymer. The following are preferable.

  In addition, the monomer component forming the (meth) acrylic polymer of the present invention can contain other functional group-containing monomers other than the hydroxyl group-containing monomer as a monofunctional monomer. Examples of other functional group-containing monomers include carboxyl group-containing monomers and monomers having a cyclic ether group.

  As the carboxyl group-containing monomer, a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and having a carboxyl group can be used without particular limitation. Examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. Can be used alone or in combination. These anhydrides can be used for itaconic acid and maleic acid. Among these, acrylic acid and methacrylic acid are preferable, and acrylic acid is particularly preferable. In addition, a carboxyl group-containing monomer can be arbitrarily used for the monomer component used for manufacture of the (meth) acrylic-type polymer of this invention, On the other hand, it is not necessary to use a carboxyl group-containing monomer. A pressure-sensitive adhesive containing a (meth) acrylic polymer obtained from a monomer component not containing a carboxyl group-containing monomer can form a pressure-sensitive adhesive layer in which metal corrosion caused by a carboxyl group is reduced.

  As the monomer having a cyclic ether group, a monomer having a polymerizable functional group having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group and a cyclic ether group such as an epoxy group or an oxetane group. It can be used without particular limitation. Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate glycidyl ether, and the like. Examples of the oxetane group-containing monomer include 3-oxetanylmethyl (meth) acrylate, 3-methyl-oxetanylmethyl (meth) acrylate, 3-ethyl-oxetanylmethyl (meth) acrylate, and 3-butyl-oxetanylmethyl (meth) acrylate. , 3-hexyl oxetanylmethyl (meth) acrylate, and the like. These can be used alone or in combination.

  In the present invention, the other functional group-containing monomer is 0.5% by weight or more from the viewpoint of enhancing adhesive force and cohesive force with respect to the total amount of the monofunctional monomer component forming the (meth) acrylic polymer. And more preferably 0.8% by weight or more. On the other hand, if the amount of the functional group-containing monomer is too large, the pressure-sensitive adhesive layer becomes hard and the adhesive strength may decrease, and the viscosity of the pressure-sensitive adhesive may become too high or gel. The other functional group-containing monomer is preferably 30% by weight or less, more preferably 27% by weight or less, and further 25% with respect to the total amount of the monofunctional monomer component forming the (meth) acrylic polymer. It is preferably not more than% by weight.

The monomer component that forms the (meth) acrylic polymer of the present invention may contain a copolymerization monomer other than the functional group-containing monomer. Examples of other copolymerizable monomers include CH ₂ ═C (R ¹ ) COOR ² (wherein R ¹ is hydrogen or a methyl group, R ² is an unsubstituted alkyl group having 1 to 9 carbon atoms or a substituted alkyl group). An alkyl (meth) acrylate represented by the following formula:

Here, the unsubstituted alkyl group having 1 to 9 carbon atoms or the substituted alkyl group as R ² represents a linear or branched alkyl group or a cyclic cycloalkyl group. Specific examples of R ² include a branched alkyl group having 3 to 9 carbon atoms and a cyclic alkyl group. In the case of a substituted alkyl group, the substituent is preferably an aryl group having 3 to 8 carbon atoms or an aryloxy group having 3 to 8 carbon atoms. The aryl group is not limited, but is preferably a phenyl group. As the alkyl (meth) acrylate, alkyl methacrylate is preferable to alkyl acrylate in terms of lowering the dielectric constant due to an increase in molar volume and a decrease in dipole moment.

Examples of such a monomer represented by CH ₂ ═C (R ¹ ) COOR ² include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and s-butyl (meth) acrylate. , T-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, isoamyl (meth) acrylate, 2- Ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, phenoxyethyl (meth) acrylate, benzyl (meth) acrylate, cyclohex Sil (meth) acrylate, 3,3,5-trimethylcyclohexyl (meth) acrylate, isobornyl (meth) acrylate. These can be used alone or in combination.

In the present invention, the (meth) acrylate represented by CH ₂ ═C (R ¹ ) COOR ² is 50% by weight or less based on the total amount of the monofunctional monomer component forming the (meth) acrylic polymer. 45% by weight or less is preferable. Furthermore, it is preferably 40% by weight or less, and more preferably 35% by weight or less. The (meth) acrylate represented by CH ₂ ═C (R ¹ ) COOR ² is preferably used in an amount of 10% by weight or more, and more preferably 15% by weight or more from the viewpoint of maintaining adhesive strength.

  Other copolymer monomers include vinyl acetate, vinyl propionate, styrene, α-methylstyrene; (meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol, (meth) acrylic acid methoxyethylene glycol, (meth) Glycol acrylic ester monomers such as methoxypolypropylene glycol acrylate; Acrylic ester monomers such as tetrahydrofurfuryl (meth) acrylate, fluorine (meth) acrylate, silicone (meth) acrylate and 2-methoxyethyl acrylate; Monomers, amino group-containing monomers, imide group-containing monomers, N-acryloylmorpholine, vinyl ether monomers and the like can also be used. Moreover, as a copolymerization monomer, the monomer which has cyclic structures, such as terpene (meth) acrylate and dicyclopentanyl (meth) acrylate, can be used.

  Furthermore, the silane type monomer containing a silicon atom, etc. are mentioned. Examples of the silane monomer include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, and 8-vinyloctyltrimethoxysilane. , 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane, and the like.

  The monomer component that forms the (meth) acrylic polymer of the present invention contains a polyfunctional monomer as necessary in order to adjust the cohesive strength of the pressure-sensitive adhesive, in addition to the monofunctional monomer exemplified above. be able to.

  The polyfunctional monomer is a monomer having at least two polymerizable functional groups having an unsaturated double bond such as a (meth) acryloyl group or a vinyl group, such as (poly) ethylene glycol di (meth) acrylate, (Poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,2-ethylene Glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,12-dodecanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylol methanetri (meth) acrylate Ester compounds of polyhydric alcohols such as carbonate and (meth) acrylic acid; allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di (meth) acrylate, hexyl di ( And (meth) acrylate. Among these, trimethylolpropane tri (meth) acrylate, hexanediol di (meth) acrylate, and dipentaerythritol hexa (meth) acrylate can be preferably used. A polyfunctional monomer can be used individually by 1 type or in combination of 2 or more types.

  The amount of the polyfunctional monomer used varies depending on the molecular weight, the number of functional groups, etc., but it is preferably used at 3 parts by weight or less, more preferably 2 parts by weight or less, with respect to a total of 100 parts by weight of the monofunctional monomer. 1 part by weight or less is more preferable. Moreover, it does not specifically limit as a lower limit, However It is preferable that it is 0 weight part or more, and it is more preferable that it is 0.001 weight part or more. Adhesive force can be improved when the usage-amount of a polyfunctional monomer exists in the said range.

  The production of such a (meth) acrylic polymer can be appropriately selected from known production methods such as radiation polymerization such as solution polymerization and UV polymerization, various radical polymerizations such as bulk polymerization and emulsion polymerization. Further, the (meth) acrylic polymer obtained may be any of a random copolymer, a block copolymer, a graft copolymer, and the like.

  The polymerization initiator, chain transfer agent, emulsifier and the like used for radical polymerization are not particularly limited and can be appropriately selected and used. In addition, the weight average molecular weight of a (meth) acrylic-type polymer can be controlled by the usage-amount of a polymerization initiator and a chain transfer agent, and reaction conditions, The usage-amount is suitably adjusted according to these kinds.

  For example, in solution polymerization or the like, for example, ethyl acetate, toluene or the like is used as a polymerization solvent. As a specific example of solution polymerization, the reaction is performed under an inert gas stream such as nitrogen, and a polymerization initiator is added, and the reaction is usually performed at about 50 to 70 ° C. under reaction conditions of about 5 to 30 hours.

  Examples of thermal polymerization initiators used for solution polymerization include 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 2,2′-azobis (2 -Methylpropionic acid) dimethyl, 4,4'-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'-azobis [2- (5-Methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis (2-methylpropionamidine) disulfate, 2,2′-azobis (N, N′-dimethyleneisobutyl) Amidine), 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (manufactured by Wako Pure Chemical Industries, Ltd., VA-057). Azo initiators: persulfates such as potassium persulfate and ammonium persulfate, di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butylperoxy Dicarbonate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3 -Tetramethylbutylperoxy-2-ethylhexanoate, di (4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butylperoxyisobutyrate, 1,1-di (t-hexylperoxy) cyclohexane , T-butyl hydroperoxide, hydrogen peroxide, etc. System initiators, redox initiators combining peroxides and reducing agents such as combinations of persulfate and sodium bisulfite, peroxides and sodium ascorbate, etc. Is not to be done.

  The polymerization initiator may be used alone or in combination of two or more, but the total content is 0.005 to 1 part by weight with respect to 100 parts by weight of the monomer. Is preferably about 0.02 to 0.5 parts by weight.

  In order to produce the (meth) acrylic polymer having the weight average molecular weight using, for example, 2,2′-azobisisobutyronitrile as the polymerization initiator, the amount of the polymerization initiator used is a monomer. The amount is preferably about 0.06 to 0.2 part by weight, more preferably about 0.08 to 0.175 part by weight with respect to 100 parts by weight of the total amount of the components.

  Examples of the chain transfer agent include lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propanol. The chain transfer agent may be used alone or in combination of two or more, but the total content is 0.1 parts by weight with respect to 100 parts by weight of the total amount of monomer components. Less than or equal to

  Examples of the emulsifier used for emulsion polymerization include anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, ammonium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, and polyoxy Nonionic emulsifiers such as ethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, and polyoxyethylene-polyoxypropylene block polymer are exemplified. These emulsifiers may be used alone or in combination of two or more.

  Further, as reactive emulsifiers, as emulsifiers into which radical polymerizable functional groups such as propenyl groups and allyl ether groups are introduced, specifically, for example, Aqualon HS-10, HS-20, KH-10, BC-05 BC-10, BC-20 (all of which are manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adeka Soap SE10N (manufactured by ADEKA), and the like. Reactive emulsifiers are preferable because they are incorporated into the polymer chain after polymerization and thus have improved water resistance. The amount of the emulsifier used is more preferably 0.3 to 5 parts by weight and 0.5 to 1 part by weight from the viewpoint of polymerization stability and mechanical stability with respect to 100 parts by weight of the total amount of monomer components.

  In addition, when the (meth) acrylic polymer is produced by radiation polymerization, it can be produced by polymerizing the monomer component by irradiating with radiation such as electron beam or UV. When the radiation polymerization is performed with an electron beam, it is not particularly necessary to include a photopolymerization initiator in the monomer component. However, when the radiation polymerization is performed with UV polymerization, the polymerization time is particularly short. For example, a photopolymerization initiator can be contained in the monomer component because of the advantages that can be achieved. A photoinitiator can be used individually by 1 type or in combination of 2 or more types.

  The photopolymerization initiator is not particularly limited, but is not particularly limited as long as it initiates photopolymerization, and a commonly used photopolymerization initiator can be used. For example, benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, α-ketol photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, photoactive oxime photopolymerization initiator, benzoin photopolymerization initiator Agents, benzyl photopolymerization initiators, benzophenone photopolymerization initiators, ketal photopolymerization initiators, thioxanthone photopolymerization initiators, acylphosphine oxide photopolymerization initiators, and the like can be used.

  Specifically, examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane- 1-one [trade name: Irgacure 651, manufactured by BASF Corporation], anisole methyl ether and the like can be mentioned. Examples of the acetophenone photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone [trade name: Irgacure 184, manufactured by BASF], 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1- [4- ( 2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one [trade name: Irgacure 2959, manufactured by BASF Corp.], 2-hydroxy-2-methyl-1-phenyl-propane- 1-one [trade name: Darocur 1173, manufactured by BASF Corporation], methoxyacetophenone, and the like can be given. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1- [4- (2-hydroxyethyl) -phenyl] -2-hydroxy-2-methylpropane-1- ON etc. are mentioned. Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalene sulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime.

  The benzoin photopolymerization initiator includes, for example, benzoin. Examples of the benzyl photopolymerization initiator include benzyl. Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like. Examples of the ketal photopolymerization initiator include benzyl dimethyl ketal. Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone and the like are included.

  Examples of the acylphosphine photopolymerization initiator include bis (2,6-dimethoxybenzoyl) phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl) phosphine oxide, bis ( 2,6-dimethoxybenzoyl) -n-butylphosphine oxide, bis (2,6-dimethoxybenzoyl)-(2-methylpropan-1-yl) phosphine oxide, bis (2,6-dimethoxybenzoyl)-(1- Methylpropan-1-yl) phosphine oxide, bis (2,6-dimethoxybenzoyl) -t-butylphosphine oxide, bis (2,6-dimethoxybenzoyl) cyclohexylphosphine oxide, bis (2,6-dimethoxybenzoyl) octylphosphine Oxides, bis (2-mes Xylbenzoyl) (2-methylpropan-1-yl) phosphine oxide, bis (2-methoxybenzoyl) (1-methylpropan-1-yl) phosphine oxide, bis (2,6-diethoxybenzoyl) (2-methyl Propan-1-yl) phosphine oxide, bis (2,6-diethoxybenzoyl) (1-methylpropan-1-yl) phosphine oxide, bis (2,6-dibutoxybenzoyl) (2-methylpropane-1- Yl) phosphine oxide, bis (2,4-dimethoxybenzoyl) (2-methylpropan-1-yl) phosphine oxide, bis (2,4,6-trimethylbenzoyl) (2,4-dipentoxyphenyl) phosphine oxide Bis (2,6-dimethoxybenzoyl) benzylphosphine oxide, bis ( , 6-Dimethoxybenzoyl) -2-phenylpropylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2-phenylethylphosphine oxide, bis (2,6-dimethoxybenzoyl) benzylphosphine oxide, bis (2,6- Dimethoxybenzoyl) -2-phenylpropylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2-phenylethylphosphine oxide, 2,6-dimethoxybenzoylbenzylbutylphosphine oxide, 2,6-dimethoxybenzoylbenzyloctylphosphine oxide, Bis (2,4,6-trimethylbenzoyl) -2,5-diisopropylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2-methylphenylphosphine oxide, bis (2, , 6-Trimethylbenzoyl) -4-methylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,5-diethylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,3 , 5,6-tetramethylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis ( 2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) isobutylphosphine oxide, 2,6-dimethoxybenzoyl-2,4,6-trimethylbenzoyl -N-butylphosphine oxide, bis (2,4,6 Trimethylbenzoyl) phenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-dibutoxyphenylphosphine oxide, 1,10-bis [bis (2,4,6-trimethylbenzoyl) phosphine oxide] decane , Tri (2-methylbenzoyl) phosphine oxide, and the like.

  Although the usage-amount of a photoinitiator is not restrict | limited in particular, For example, 0.01-5 weight part with respect to 100 weight part of said monomer components, Preferably it is 0.05-3 weight part, More preferably, it is 0.05- 1.5 parts by weight, more preferably 0.1 to 1 part by weight

  If the amount of the photopolymerization initiator used is less than 0.01 parts by weight, the polymerization reaction may be insufficient. When the usage-amount of a photoinitiator exceeds 5 weight part, a photoinitiator may absorb an ultraviolet-ray and an ultraviolet-ray may not reach the inside of an adhesive layer. In this case, the polymerization rate is lowered, or the molecular weight of the produced polymer is reduced. And thereby, the cohesive force of the pressure-sensitive adhesive layer to be formed becomes low, and when the pressure-sensitive adhesive layer is peeled off from the film, a part of the pressure-sensitive adhesive layer may remain on the film and the film may not be reused. . In addition, a photopolymerization initiator can be used individually by 1 type or in combination of 2 or more types.

  The weight average molecular weight of the (meth) acrylic polymer of the present invention is preferably 400,000 to 2,500,000, more preferably 600,000 to 2,200,000. By making the weight average molecular weight larger than 400,000, it is possible to satisfy the durability of the pressure-sensitive adhesive layer, or to suppress the occurrence of adhesive residue due to the reduced cohesive force of the pressure-sensitive adhesive layer. On the other hand, when the weight average molecular weight is larger than 2.5 million, the bonding property and the adhesive strength tend to be lowered. Furthermore, in the solution system, the viscosity becomes too high, and coating may be difficult. The weight average molecular weight is a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene. In addition, it is difficult to measure the molecular weight of the (meth) acrylic polymer obtained by radiation polymerization.

<Measurement of weight average molecular weight>
The weight average molecular weight of the obtained (meth) acrylic polymer was measured by GPC (gel permeation chromatography). The sample used was a filtrate obtained by dissolving the sample in tetrahydrofuran to make a 0.1 wt% solution, which was allowed to stand overnight, and then filtered through a 0.45 μm membrane filter.
・ Analyzer: HLC-8120GPC manufactured by Tosoh Corporation
Column: Tosoh Corporation, (meth) acrylic polymer: GM7000H _XL + GMH _XL + GMH _XL
Aromatic polymer: G3000HXL + 2000HXL + G1000HXL
・ Column size: 7.8mmφ × 30cm each 90cm in total
・ Eluent: Tetrahydrofuran (concentration 0.1% by weight)
・ Flow rate: 0.8ml / min
・ Inlet pressure: 1.6 MPa
・ Detector: Differential refractometer (RI)
-Column temperature: 40 ° C
・ Injection volume: 100 μl
・ Eluent: Tetrahydrofuran ・ Detector: Differential refractometer ・ Standard sample: Polystyrene

  The pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer for transparent conductive film of the present invention can contain a crosslinking agent. Examples of crosslinking agents include isocyanate crosslinking agents, epoxy crosslinking agents, silicone crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, silane crosslinking agents, alkyletherified melamine crosslinking agents, metal chelate crosslinking agents, Crosslinkers such as oxides are included. A crosslinking agent can be used alone or in combination of two or more. As said crosslinking agent, an isocyanate type crosslinking agent and an epoxy-type crosslinking agent are used preferably.

  The crosslinking agent may be used alone or in combination of two or more, but the total content is 100 parts by weight of the (meth) acrylic polymer. It can contain in 5 weight part or less of range. The content of the crosslinking agent is preferably 0.01 to 5 parts by weight, more preferably 0.01 to 4 parts by weight, and further preferably 0.02 to 3 parts by weight.

  The isocyanate-based crosslinking agent refers to a compound having two or more isocyanate groups in a molecule (including isocyanate-regenerating functional groups in which isocyanate groups are temporarily protected by a blocking agent or quantification).

  Examples of the isocyanate-based crosslinking agent include aromatic isocyanates such as tolylene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

  More specifically, for example, lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate, alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate, 2,4-tolylene diisocyanate, Aromatic diisocyanates such as 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, polymethylene polyphenyl isocyanate, trimethylolpropane / tolylene diisocyanate trimer adduct (trade name Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.), tri Methylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name Coronate HL), hexamethylene diiso Isocyanurate of anate (made by Nippon Polyurethane Industry Co., Ltd., trade name Coronate HX), etc., xylylene diisocyanate trimethylolpropane adduct (Mitsui Chemicals, trade name D110N), hexamethylene diisocyanate trimethylolpropane Additives (Mitsui Chemicals, trade name D160N); polyether polyisocyanate, polyester polyisocyanate, adducts of these with various polyols, polyfunctionalized polyisocyanate, burette, allophanate, etc. An isocyanate etc. can be mentioned. Of these, it is preferable to use an aliphatic isocyanate because of its high reaction rate.

  The isocyanate-based crosslinking agent may be used alone or in combination of two or more, but the total content is 100 parts by weight of the (meth) acrylic polymer. On the other hand, it is preferable to contain 0.01-5 weight part of the said isocyanate type crosslinking agent, Furthermore, it is preferable to contain 0.01-4 weight part, Furthermore, it is preferable to contain 0.02-3 weight part. . It can be appropriately contained in consideration of cohesive force and prevention of peeling in a durability test.

  In addition, in the aqueous dispersion of the modified (meth) acrylic polymer prepared by emulsion polymerization, it is not necessary to use an isocyanate-based crosslinking agent. However, if necessary, it is blocked because it easily reacts with water. Isocyanate-based crosslinking agents can also be used.

  The said epoxy type crosslinking agent says the polyfunctional epoxy compound which has 2 or more of epoxy groups in 1 molecule. Examples of the epoxy crosslinking agent include bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, N, N, N ′, N′-tetraglycidyl-m-xylenediamine, diglycidylaniline, diamine glycidylamine, 1 , 3-bis (N, N-diglycidylaminomethyl) cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether , Polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether Glycerin diglycidyl ether, glycerin triglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris (2-hydroxy Ethyl) isocyanurate, resorcin diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having two or more epoxy groups in the molecule. Examples of the epoxy-based crosslinking agent include commercially available products such as trade names “Tetrad C” and “Tetrad X” manufactured by Mitsubishi Gas Chemical Company.

  The epoxy crosslinking agent may be used alone or in combination of two or more. However, the total content is 100 parts by weight of the (meth) acrylic polymer. On the other hand, it is preferable to contain 0.01-5 weight part of the said epoxy type crosslinking agent, Furthermore, it is preferable to contain 0.01-4 weight part, Furthermore, it is preferable to contain 0.02-3 weight part. . It can be appropriately contained in consideration of cohesive force and prevention of peeling in a durability test.

  The peroxide crosslinking agent can be used as appropriate as long as it generates radical active species by heating to cause the crosslinking of the base polymer of the pressure-sensitive adhesive, but in consideration of workability and stability, 1 It is preferable to use a peroxide having a minute half-life temperature of 80 ° C to 160 ° C, and it is more preferable to use a peroxide having a temperature of 90 ° C to 140 ° C.

  Examples of the peroxide that can be used include di (2-ethylhexyl) peroxydicarbonate (1 minute half-life temperature: 90.6 ° C.), di (4-t-butylcyclohexyl) peroxydicarbonate (1 Minute half-life temperature: 92.1 ° C.), di-sec-butyl peroxydicarbonate (1 minute half-life temperature: 92.4 ° C.), t-butyl peroxyneodecanoate (1 minute half-life temperature: 103 0.5 ° C), t-hexyl peroxypivalate (1 minute half-life temperature: 109.1 ° C), t-butyl peroxypivalate (1 minute half-life temperature: 110.3 ° C), dilauroyl peroxide ( 1 minute half-life temperature: 116.4 ° C), di-n-octanoyl peroxide (1 minute half-life temperature: 117.4 ° C), 1,1,3,3-tetramethylbutylper Xyl-2-ethylhexanoate (1 minute half-life temperature: 124.3 ° C), di (4-methylbenzoyl) peroxide (1 minute half-life temperature: 128.2 ° C), dibenzoyl peroxide (half-minute for 1 minute) Period temperature: 130.0 ° C.), t-butyl peroxyisobutyrate (1 minute half-life temperature: 136.1 ° C.), 1,1-di (t-hexylperoxy) cyclohexane (1 minute half-life temperature: 149.2 ° C.). Especially, since the crosslinking reaction efficiency is excellent, di (4-t-butylcyclohexyl) peroxydicarbonate (1 minute half-life temperature: 92.1 ° C.), dilauroyl peroxide (1 minute half-life temperature: 116. 4 ° C), dibenzoyl peroxide (1 minute half-life temperature: 130.0 ° C) and the like are preferably used.

  The peroxide half-life is an index representing the decomposition rate of the peroxide, and means the time until the remaining amount of peroxide is reduced to half. The decomposition temperature for obtaining a half-life at an arbitrary time and the half-life time at an arbitrary temperature are described in the manufacturer's catalog, for example, “Organic peroxide catalog 9th edition of Nippon Oil & Fats Co., Ltd.” (May 2003) ".

  The peroxide may be used alone or as a mixture of two or more, but the total content is based on 100 parts by weight of the (meth) acrylic polymer. The peroxide is 0.02 to 2 parts by weight, preferably 0.05 to 1 part by weight. In order to adjust processability, reworkability, cross-linking stability, peelability, and the like, it is appropriately selected within this range.

  In addition, as a measuring method of the peroxide decomposition amount which remained after the reaction process, it can measure by HPLC (high performance liquid chromatography), for example.

  More specifically, for example, about 0.2 g of the pressure-sensitive adhesive after the reaction treatment is taken out, immersed in 10 ml of ethyl acetate, extracted with shaking at 25 ° C. and 120 rpm for 3 hours, and then at room temperature. Let stand for days. Next, 10 ml of acetonitrile was added, shaken at 120 rpm at 25 ° C. for 30 minutes, and about 10 μl of the extract obtained by filtration through a membrane filter (0.45 μm) was injected into the HPLC for analysis. The amount of peroxide can be set.

  Moreover, you may use together an organic type crosslinking agent and a polyfunctional metal chelate as a crosslinking agent. A polyfunctional metal chelate is one in which a polyvalent metal is covalently or coordinately bonded to an organic compound. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti, and the like. Can be mentioned. Examples of the atom in the organic compound that is covalently bonded or coordinated include an oxygen atom, and examples of the organic compound include an alkyl ester, an alcohol compound, a carboxylic acid compound, an ether compound, and a ketone compound.

  In order to improve the adhesive force, the (meth) acrylic oligomer can be contained in the pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer for transparent conductive film of the present invention. The (meth) acrylic oligomer is preferably a polymer having a Tg higher than that of the (meth) acrylic polymer of the present invention and a small weight average molecular weight. Such a (meth) acrylic oligomer functions as a tackifying resin and has the advantage of increasing the adhesive force without increasing the dielectric constant.

  The (meth) acrylic oligomer preferably has a Tg of about 0 ° C. or higher and 300 ° C. or lower, preferably about 20 ° C. or higher and 300 ° C. or lower, more preferably about 40 ° C. or higher and 300 ° C. or lower. When the Tg is less than about 0 ° C., the cohesive force of the pressure-sensitive adhesive layer at room temperature or higher is lowered, and the holding characteristics and the adhesiveness at high temperature may be lowered. The Tg of the (meth) acrylic oligomer is a theoretical value calculated based on the Fox equation, similar to the Tg of the (meth) acrylic polymer.

  The weight average molecular weight of the (meth) acrylic oligomer is 1000 or more and less than 30000, preferably 1500 or more and less than 20000, and more preferably 2000 or more and less than 10,000. If the weight average molecular weight is 30000 or more, the effect of improving the adhesive strength may not be sufficiently obtained. On the other hand, if the molecular weight is less than 1000, the molecular weight may be low, which may cause a decrease in adhesive strength and retention characteristics. In this invention, the measurement of the weight average molecular weight of a (meth) acrylic-type oligomer can be calculated | required in polystyrene conversion by GPC method. Specifically, TSKgelGMH-H (20) × 2 columns are used in HPLC 8020 manufactured by Tosoh Corporation, and the measurement is performed with a tetrahydrofuran solvent at a flow rate of about 0.5 ml / min.

  Examples of the monomer constituting the (meth) acrylic oligomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, and isobutyl (meth) acrylate. , S-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, octyl (Meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undeci Alkyl (meth) acrylates such as (meth) acrylate and dodecyl (meth) acrylate; (meth) acrylic acid and alicyclic such as cyclohexyl (meth) acrylate, isobornyl (meth) acrylate and dicyclopentanyl (meth) acrylate An ester with a group alcohol; an aryl (meth) acrylate such as phenyl (meth) acrylate and benzyl (meth) acrylate; a (meth) acrylate obtained from a terpene compound derivative alcohol; and the like. Such (meth) acrylates can be used alone or in combination of two or more.

  Examples of (meth) acrylic oligomers include alkyl (meth) acrylates in which alkyl groups such as isobutyl (meth) acrylate and t-butyl (meth) acrylate have a branched structure; cyclohexyl (meth) acrylate and isobornyl (meth) Esters of (meth) acrylic acid and alicyclic alcohols such as acrylate and dicyclopentanyl (meth) acrylate; cyclic structures such as aryl (meth) acrylate such as phenyl (meth) acrylate and benzyl (meth) acrylate It is preferable that an acrylic monomer having a relatively bulky structure typified by (meth) acrylate having a monomer content is included as a monomer unit. By giving such a bulky structure to the (meth) acrylic oligomer, the adhesiveness of the pressure-sensitive adhesive layer can be further improved. In particular, those having a ring structure in terms of bulkiness are highly effective, and those having a plurality of rings are more effective. In addition, when ultraviolet rays (ultraviolet rays) are employed in the synthesis of the (meth) acrylic oligomer or in the production of the pressure-sensitive adhesive layer, those having a saturated bond are preferred in that they are less likely to cause polymerization inhibition. An alkyl (meth) acrylate having an alkyl group having a branched structure or an ester with an alicyclic alcohol can be suitably used as a monomer constituting the (meth) acrylic oligomer.

  From this point, suitable (meth) acrylic oligomers include, for example, a copolymer of cyclohexyl methacrylate (CHMA) and isobutyl methacrylate (IBMA), and a copolymer of cyclohexyl methacrylate (CHMA) and isobornyl methacrylate (IBXMA). Polymer, copolymer of cyclohexyl methacrylate (CHMA) and acryloylmorpholine (ACMO), copolymer of cyclohexyl methacrylate (CHMA) and diethylacrylamide (DEAA), copolymer of 1-adamantyl acrylate (ADA) and methyl methacrylate (MMA) Polymer, copolymer of dicyclopentanyl methacrylate (DCPMA) and isobornyl methacrylate (IBXMA), cyclopentanyl methacrylate (DCPMA) and methyl Copolymer of acrylate (MMA), dicyclopentanyl methacrylate (DCPMA), cyclohexyl methacrylate (CHMA), isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA), dicyclopentanyl acrylate (DCPA), 1 -Adamantyl methacrylate (ADMA), 1-adamantyl acrylate (ADA) homopolymers, and the like. In particular, an oligomer containing CHMA as a main component is preferable.

  In the pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer for transparent conductive film of the present invention, when the (meth) acrylic oligomer is used, its content is not particularly limited, but with respect to 100 parts by weight of the (meth) acrylic polymer. It is preferably 70 parts by weight or less, more preferably 1 to 70 parts by weight, further preferably 2 to 50 parts by weight, and further preferably 3 to 40 parts by weight. When the added amount of the (meth) acrylic oligomer exceeds 70 parts by weight, there is a problem that the elastic modulus is increased and the adhesiveness at low temperature is deteriorated. In addition, it is effective from the point of the improvement effect of adhesive force, when mix | blending 1 weight part or more of (meth) acrylic-type oligomers.

  Furthermore, the pressure-sensitive adhesive of the present invention may contain a silane coupling agent in order to increase the water resistance at the interface when applied to a hydrophilic adherend such as glass of the pressure-sensitive adhesive layer. The amount of the silane coupling agent is preferably 1 part by weight or less, more preferably 0.01 to 1 part by weight, still more preferably 0.02 to 0 parts per 100 parts by weight of the (meth) acrylic polymer. .6 parts by weight. If the amount of the silane coupling agent is too large, the adhesion to the glass increases and the removability is poor, and if it is too small, the durability decreases, which is not preferable.

  Examples of the silane coupling agent that can be preferably used include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2- (3,4 epoxy cyclohexyl). ) Epoxy group-containing silane coupling agent such as ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1 , 3-dimethylbutylidene) propylamine, amino group-containing silane coupling agents such as N-phenyl-γ-aminopropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, etc. (Meta) Acry Group-containing silane coupling agents, such as isocyanate group-containing silane coupling agents such as 3-isocyanate propyl triethoxysilane and the like.

  Furthermore, the pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer for a transparent conductive film of the present invention may contain other known additives, for example, powders such as rust preventives, colorants, pigments, Dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers , Metal powders, particles, foils, etc. can be added as appropriate according to the intended use. The ratio of the additive is appropriately adjusted within a range of 30 parts by weight or less with respect to 100 parts by weight of the (meth) acrylic polymer.

  As said additive, a rust preventive agent is suitable, for example. By containing the rust preventive agent, for example, when the adherend of the pressure-sensitive adhesive layer is a metal, it has an excellent corrosion prevention effect on the adherend. In particular, when the (meth) acrylic polymer is a (meth) acrylic polymer obtained from a monomer component not containing a carboxy group-containing monomer, the metal corrosion of the adherend is more effectively reduced. be able to.

  The said rust preventive agent contains the compound which prevents the rust (rust) and corrosion of a metal. Although it does not specifically limit as a rust preventive agent, For example, an amine compound, a benzotriazole type compound, nitrites, etc. are mentioned. In addition, ammonium benzoate, ammonium phthalate, ammonium stearate, ammonium palmitate, ammonium oleate, ammonium carbonate, dicyclohexylamine benzoate, urea, urotropine, thiourea, phenyl carbamate, cyclohexylammonium-N-cyclohexyl And carbamate (CHC). In addition, a rust preventive agent can be used individually or in combination of 2 or more types.

  Examples of the amine compound include 2-amino-2-methyl-1-propanol, monoethanolamine, monoisopropanolamine, diethylethanolamine, hydroxy group-containing amine compounds such as ammonia and aqueous ammonia; cyclic amines such as morpholine; cyclohexyl And cyclic alkylamine compounds such as amines; and linear alkylamines such as 3-methoxypropylamine. Examples of the nitrites include dicyclohexylammonium nitrite (DICHAN), diisopropylammonium nitrite (DIPAN), sodium nitrite, potassium nitrite, and calcium nitrite.

  Among the above rust preventives, from the viewpoint of compatibility with (meth) acrylic polymer and transparency, when (meth) acrylic polymer is reacted after addition, reaction of (meth) acrylic polymer (crosslinking, polymerization) A benzotriazole-based compound is preferable because it is difficult to inhibit this. In addition, a benzotriazole-based compound is preferable as a rust preventive from the viewpoint that adhesion reliability, transparency, and corrosion prevention characteristics can be obtained at a high level in a balanced manner and an excellent appearance can be obtained.

  The rust preventive may be used alone or in combination of two or more, but the total content is based on 100 parts by weight of the (meth) acrylic polymer. And can be contained in the range of 30 parts by weight or less. The content of the crosslinking agent is preferably 0.005 to 30 parts by weight, more preferably 0.005 to 20 parts by weight, and still more preferably 0.01 to 15 parts by weight. When the content is 0.02 part by weight or more, good corrosion prevention performance is easily obtained. On the other hand, when the content is 30 parts by weight or less, it is easy to ensure transparency, and it is easy to ensure adhesion reliability such as anti-foaming peelability.

  When a benzotriazole-based compound is used as the rust inhibitor, the content thereof is preferably 0.02 to 3 parts by weight, more preferably 0.02 to 100 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. 2.5 parts by weight, more preferably 0.02 to 2 parts by weight.

（但し、上記式（１）において、Ｒ^１及びＲ^２は同一又は異なって、Ｒ^１はベンゼン環上の置換基であって、炭素数１〜６のアルキル基、炭素数１〜６のアルコキシ基、炭素数６〜１４のアリール基、アミノ基、モノ又はジＣ_１−１０アルキルアミノ基、アミノ−Ｃ_１−６アルキル基、モノ又はジＣ_１−１０アルキルアミノ−Ｃ_１−６アルキル基、メルカプト基、炭素数１〜６のアルコキシカルボニル基、又は炭素数１〜６のアルコキシ基等の置換基を示し、ｎは０〜４の整数であって、ｎが２以上である場合は、ｎ個のＲ^１は同一であっても、異なっていても良く、Ｒ^２は、水素原子、炭素数１〜１２のアルキル基、炭素数１〜１２のアルコキシ基、炭素数６〜１４のアリール基、アミノ基、モノ又はジＣ_１−１０アルキルアミノ基、アミノ−Ｃ_１−６アルキル基、モノ又はジＣ_１−１０アルキルアミノ−Ｃ_１−６アルキル基、メルカプト基、炭素数１〜１２のアルコキシカルボニル基、又は炭素数１〜１２のアルコキシ基等の置換基を示す。） The benzotriazole-based compound is not particularly limited as long as it is a compound having a benzotriazole skeleton, but having a structure represented by the following formula (1) provides a more excellent corrosion prevention effect. preferable.

(In the above formula (1), R ¹ and R ² are the same or different, and R ¹ is a substituent on the benzene ring, which is an alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 6 carbon atoms. Group, aryl group having 6 to 14 carbon atoms, amino group, mono- or di-C _1-10 alkylamino group, amino-C _1-6 alkyl group, mono- or di-C _1-10 alkylamino-C _1-6 alkyl group Represents a substituent such as a mercapto group, an alkoxycarbonyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, where n is an integer of 0 to 4 and n is 2 or more, n pieces of R ¹ may be the same or different, and R ² is a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or an aryl having 6 to 14 carbon atoms. Group, amino group, mono or di C _1-10 alkylamino group An amino-C _1-6 alkyl group, a mono- or di-C _1-10 alkylamino-C _1-6 alkyl group, a mercapto group, an alkoxycarbonyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, or the like Represents a substituent of

From the viewpoint of obtaining a more excellent corrosion prevention effect, R ¹ is preferably an alkyl group having 1 to 3 carbon atoms, an alkoxycarbonyl group, or the like, and more preferably a methyl group or the like. N is preferably 0 or 1. From the same viewpoint, R ² is preferably a hydrogen atom, a mono- or di-C _1-10 alkylamino-C _1-6 alkyl group, etc., and a hydrogen atom, a di-C _1-8 alkylamino C _1-4 alkyl group, etc. Is more preferable.

  The adhesive layer for transparent conductive films of this invention is formed from the said adhesive. The thickness in particular of an adhesive layer is not restrict | limited, For example, it is about 1-400 micrometers. Moreover, the thickness of the said adhesive layer can set a preferable range suitably according to the manufacturing method of the (meth) acrylic-type polymer used for an adhesive. For example, when producing a (meth) acrylic polymer by solution polymerization or the like, the thickness of the pressure-sensitive adhesive layer is preferably 1 to 100 μm, more preferably 2 to 50 μm, still more preferably 2 to 40 μm, More preferably, it is 5-35 micrometers. Moreover, when manufacturing a (meth) acrylic-type polymer by radiation polymerization etc., the thickness of the said adhesive layer has preferable 50-400 micrometers, More preferably, it is 75-300 micrometers, More preferably, it is 100-200 micrometers. .

  The pressure-sensitive adhesive layer for transparent conductive film of the present invention preferably has a relative dielectric constant of 3.5 or less at a frequency of 100 kHz, more preferably 3.3 or less, still more preferably 3.2 or less, Preferably it is 3.0 or less.

  Moreover, it is preferable that the gel fraction of the adhesive layer for transparent conductive films of this invention is 20 to 98 weight%. The gel fraction of the pressure-sensitive adhesive layer is more preferably 30 to 98% by weight, still more preferably 40 to 95% by weight. When the pressure-sensitive adhesive contains a cross-linking agent, the gel fraction can be controlled by adjusting the addition amount of the entire cross-linking agent and sufficiently considering the influence of the cross-linking temperature and the cross-linking time. When the gel fraction is small, the cohesive force is poor, and when it is too large, the adhesive force may be poor. The pressure-sensitive adhesive layer having such a gel fraction has a very small increase in adhesive force after being applied to an adherend, and exhibits the characteristics that it can be easily re-peeled without any adhesive residue even after being applied for a long time. The

  The pressure-sensitive adhesive layer for transparent conductive film of the present invention preferably has a haze value of 2% or less when the thickness of the pressure-sensitive adhesive layer is 25 μm. If the haze is 2% or less, the transparency required when the pressure-sensitive adhesive layer is used in an optical member can be satisfied. The haze value is preferably 0 to 1.5%, and more preferably 0 to 1%. In addition, if a haze value is 2% or less, it can be satisfied as an optical use. If the haze value exceeds 2%, white turbidity occurs, which is not preferable for optical film applications.

  It is considered that the transparency of the pressure-sensitive adhesive layer is determined by the total amount of the cyclic nitrogen-containing monomer and the copolymerized monomer (particularly, the hydroxyl group-containing monomer) with respect to the total amount of the monofunctional monomer in the monomer component. If the total amount is large, the transparency is excellent, but if it is too large, other properties may be adversely affected. Therefore, when the ratio of the cyclic nitrogen-containing monomer is small, the transparency can be controlled by using, for example, a hydroxyl group-containing monomer as a copolymerization monomer.

  The pressure-sensitive adhesive layer can be formed as a pressure-sensitive adhesive sheet by, for example, applying the pressure-sensitive adhesive to a support and drying and removing a polymerization solvent and the like. In applying the adhesive, one or more solvents other than the polymerization solvent may be added as appropriate.

  Various methods are used as a method of applying the adhesive. Specifically, for example, roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Examples thereof include an extrusion coating method.

  The heating and drying temperature is preferably 40 ° C to 200 ° C, more preferably 50 ° C to 180 ° C, and particularly preferably 70 ° C to 170 ° C. By setting the heating temperature in the above range, an adhesive layer having excellent adhesive properties can be obtained. As the drying time, an appropriate time can be adopted as appropriate. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

  The pressure-sensitive adhesive layer is formed by manufacturing the (meth) acrylic polymer of the present invention by polymerizing the monomer component by irradiating the monomer component with ultraviolet rays. At the same time, an adhesive layer can be formed. The monomer component can contain a material that can be appropriately blended with the pressure-sensitive adhesive such as a crosslinking agent. As the monomer component, a part of the monomer component previously polymerized into a syrup can be used for ultraviolet irradiation. For ultraviolet irradiation, a high pressure mercury lamp, a low pressure mercury lamp, a metal halide lamp, or the like can be used.

  As the support, for example, a release-treated sheet can be used. A silicone release liner is preferably used as the release-treated sheet.

  When the pressure-sensitive adhesive layer is exposed on the release-treated sheet, the pressure-sensitive adhesive layer may be protected with a release-treated sheet (separator) until practical use. . In practical use, the peeled sheet is peeled off.

  Examples of the constituent material of the separator include, for example, plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films, porous materials such as paper, cloth, and nonwoven fabric, nets, foam sheets, metal foils, and laminates thereof. Although a thin leaf body etc. can be mentioned, a plastic film is used suitably from the point which is excellent in surface smoothness.

  The plastic film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. For example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, and a vinyl chloride co-polymer are used. Examples thereof include a polymer film, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyurethane film, and an ethylene-vinyl acetate copolymer film.

  The thickness of the separator is usually about 5 to 200 μm, preferably about 5 to 100 μm. For the separator, if necessary, mold release and antifouling treatment with a silicone type, fluorine type, long chain alkyl type or fatty acid amide type release agent, silica powder, etc., coating type, kneading type, vapor deposition type It is also possible to carry out antistatic treatment such as. In particular, when the surface of the separator is appropriately subjected to a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment, the peelability from the pressure-sensitive adhesive layer can be further improved.

  The pressure-sensitive adhesive layer for transparent conductive film of the present invention is applied to the functional layer of the transparent conductive film and used as a transparent conductive film with a pressure-sensitive adhesive layer.

  The pressure-sensitive adhesive layer can be formed directly on the functional layer of the transparent conductive film, and the pressure-sensitive adhesive layer can be formed on the optical member by drying and removing the polymerization solvent. Moreover, the adhesive layer formed in the separator which carried out the peeling process can be appropriately transcribe | transferred to the functional layer of a transparent conductive film, and a transparent conductive film with an adhesive layer can be formed.

  In addition, the sheet | seat which carried out the peeling process used in preparation of said transparent conductive film with an adhesive layer can be used as a separator of an optical member with an adhesive layer as it is, and can simplify in a process surface.

  Further, in the transparent conductive film with the pressure-sensitive adhesive layer, in forming the pressure-sensitive adhesive layer, after forming an anchor layer on the surface of the optical member or performing various easy adhesion treatments such as corona treatment and plasma treatment. An adhesive layer can be formed. Moreover, you may perform an easily bonding process on the surface of an adhesive layer.

  The said transparent conductive film with an adhesive layer is used in formation of various apparatuses, such as a touch panel and a liquid crystal display. In particular, it can be preferably used as an electrode plate for a touch panel. The touch panel is suitably used for various detection methods (for example, a resistance film method, a capacitance method, etc.).

  In a capacitive touch panel, a transparent conductive film provided with a transparent conductive thin film having a predetermined pattern shape is usually formed on the entire surface of the display unit.

  An example of a capacitive touch panel in which the transparent conductive film with an adhesive layer of the present invention is used is shown in FIG. In FIG. 2, 1 is a capacitive touch panel, 2 is a decorative panel, 3 is an adhesive layer or an adhesive sheet, 4 is a transparent conductive film, and 5 is a hard coat film. The decorative panel 2 is preferably a glass plate or a transparent acrylic plate (PMMA plate). The hard coat film 5 is preferably a transparent plastic film such as a PET film subjected to a hard coat treatment.

  For example, in FIG. 2, the pressure-sensitive adhesive layer 3 sandwiched between two transparent conductive films 4 corresponds to the pressure-sensitive adhesive layer 3 for transparent conductive film of the present invention shown in FIG. In FIG. 2, the two transparent conductive films 4 are provided such that both functional layers 8 are on the pressure-sensitive adhesive layer 3 side.

  In addition, in FIG. 2, although the case where the functional layer 8 of the transparent conductive film 4 was arrange | positioned on both sides of the adhesive layer 3 for transparent conductive films was demonstrated, the adhesive layer 3 for transparent conductive films of this invention. If the functional layer of the transparent conductive film with the pressure-sensitive adhesive layer is disposed on one side, the other side of the pressure-sensitive adhesive layer 3 is not particularly limited. The conductive thin film 6 can be disposed. Since the capacitive touch panel 1 uses the pressure-sensitive adhesive layer 3 for a transparent conductive film of the present invention, it has high sebum resistance, can be made thin, and is excellent in operational stability. Also, the appearance and visibility are good.

Moreover, the adhesive layer for transparent conductive films of this invention can be used also in touch panels other than the said structure. Specifically, transparent substrate (for example, glass) / adhesive layer (or adhesive sheet) / transparent conductive film / adhesive layer (or adhesive sheet) / transparent conductive film / adhesive layer (or adhesive sheet) / Liquid crystal display (LCD);
Configuration of transparent substrate with transparent conductive thin film such as ITO (for example, glass) / adhesive layer (or adhesive sheet) / transparent conductive film / adhesive layer (or adhesive sheet) / liquid crystal display (LCD); Can be applied.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, all the parts and% in each example are based on weight. Evaluation items in Examples and the like were measured as follows.

Example 1
<Preparation of monofunctional monomer component>
2-ethylhexyl acrylate (2EHA) 37 parts by weight, isostearyl acrylate (ISA) 37 parts by weight, N-vinyl-2-pyrrolidone (NVP) 22 parts by weight, 4-hydroxybutyl acrylate (HBA) 4 parts by weight, 0.05 parts by weight of a photopolymerization initiator (trade name: Irgacure 184, manufactured by BASF) and 0.05 part by weight of a photopolymerization initiator (trade name: Irgacure 651, manufactured by BASF) were charged into a four-necked flask. A monomer mixture was prepared. Next, the monomer mixture was partially photopolymerized by exposing it to ultraviolet rays under a nitrogen atmosphere to obtain a partially polymerized product (acrylic polymer syrup) having a polymerization rate of about 10% by weight.

  After adding 0.035 part by weight of trimethylolpropane triacrylate (TMPTA) and 0.3 part of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd .: KBM-403) to 100 parts by weight of the acrylic polymer syrup described above. These were uniformly mixed to prepare monomer components.

<Preparation of adhesive layer>
Next, the final thickness of the monomer component prepared above is 100 μm on the release-treated surface of a 38 μm-thick polyester film (trade name: Diafoil MRF, manufactured by Mitsubishi Plastics Co., Ltd.) whose one side is peel-treated with silicone. The coating layer was formed by coating as described above. Next, a 38 μm thick polyester film (trade name: Diafoil MRE, manufactured by Mitsubishi Plastics Co., Ltd.) having one surface peeled with silicone on the surface of the applied monomer component, the peel-treated surface of the film is on the coating layer side. It was coated as follows. Thereby, the coating layer of the monomer component was shielded from oxygen. Using a chemical light lamp (manufactured by Toshiba Corporation) on the sheet having the coating layer thus obtained, ultraviolet rays having an illuminance of 5 mW / cm ² (measured with Topcon UVR-T1 having a maximum sensitivity at about 350 nm) are applied for 360 seconds. Irradiation was performed to cure the coating layer to form an adhesive layer, and an adhesive sheet was prepared. The polyester film coated on both sides of the pressure-sensitive adhesive layer functions as a release liner.

Examples 2 to 10 and Comparative Examples 1 to 4
In Example 1, the type and composition ratio of the monofunctional monomer used for the preparation of the monomer component, the type and blending amount of the polyfunctional monomer, and the thickness of the pressure-sensitive adhesive layer were changed as shown in Table 1. Performed the same operation as Example 1, and created the adhesive sheet.

  The following evaluation was performed about the adhesive sheet (sample) obtained by the said Example and comparative example. The evaluation results are shown in Table 1.

<Measurement of gel fraction>
A predetermined amount (initial weight W1) is taken out from the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet, immersed in an ethyl acetate solution and allowed to stand at room temperature for one week, then insoluble matter is taken out, and the dried weight (W2) is measured. It was calculated as follows.
Gel fraction = (W2 / W1) × 100

<Sebum resistance>
(Adjustment of sebum fluid)
41 parts by weight of triglyceride (trade name: Lexol GT-865, manufactured by INOLEX), 16.4 parts by weight of isostearic acid (manufactured by Wako Pure Chemical Industries, Ltd.), 12 parts by weight of squalane (manufactured by Wako Pure Chemical Industries, Ltd.) It mixed uniformly and produced sebum liquid.
(Measurement of sebum swelling degree)
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut out to 3 cm × 3 cm, one of the silicone-treated PET films was peeled off, and the pressure-sensitive adhesive surface was attached to one side of a 100 μm PET film with a hand roller. The PET film subjected to the silicone treatment was peeled off, and the pressure-sensitive adhesive surface was attached to one surface of alkali glass to obtain a test piece (100 μm PET film / pressure-sensitive adhesive layer / alkali glass). The obtained test piece was immersed in the prepared sebum for 120 hours under conditions of 50 ° C. and 95% RH, and the area (cm ² ) after swelling was measured. The degree of sebum swelling was determined by the following method.

<Humidification cloudiness resistance 1>
A film having a layer structure of transparent conductive film (HC (clear hard coat layer) / PET layer (PET base material layer) / ITO layer) is peeled off from the pressure-sensitive adhesive sheet on which one silicone treatment is applied. ) Were bonded so that the HC surface (clear hard coat surface) was in contact with each other to obtain a laminated structure (having a layer structure of “adhesive sheet (adhesive layer) / transparent conductive film”).

  The obtained laminated structure was allowed to stand in a temperature environment of 140 ° C. for 90 minutes to crystallize ITO. Next, the other adhesive surface of the laminated structure and glass (trade name “MICRO SLIDE GLASS”, product number “S-1111”, manufactured by Matsunami Glass Co., Ltd.) were bonded to obtain a test piece. In addition, the schematic sectional drawing of this test piece consists of ITO layer 6 / PET base material layer 7 / HC layer 8 / adhesive layer 3 / glass 9 as shown in FIG.

  The haze of the test piece was measured using a haze meter (trade name “HM-150”, manufactured by Murakami Color Research Laboratory Co., Ltd.) in an environment of 23 ° C. and 50% RH. And it confirmed that haze (initial haze) was 2.0% or less.

Next, the test piece was stored in an environment of 60 ° C. and 95% RH (in a moist heat environment) for 500 hours, and then taken out in an environment of 23 ° C. and 50% RH. It measured similarly.
And it evaluated by the following reference | standard.
A: Haze of test piece immediately after removal is less than 2.0% (very good)
◯: The haze of the test piece immediately after removal is 2.0% or more and less than 5.0% (good)
X: Haze of test piece immediately after taking out is 5.0% or more (defect)

<Humidity resistance 2>
The transparent conductive film (film having a layer structure of HC (clear hard coat) layer / PET base material layer / ITO layer) was left in a temperature environment of 140 ° C. for 90 minutes to crystallize the ITO layer.

  One of the adhesive-treated PET films subjected to silicone treatment was peeled off and bonded so that the HC layer surface of the transparent conductive film was in contact with the adhesive surface. And from the obtained laminated structure (silicone-treated PET film / adhesive layer / transparent conductive film), the silicone-treated PET film is peeled, and the adhesive surface and glass (trade name: MICRO SLIDE GLASS) , Product number: S-1111, manufactured by Matsunami Glass Co., Ltd.) was used as a test piece. As shown in FIG. 3, the schematic cross-sectional view of the test piece is composed of ITO layer 6 / PET base material layer 7 / HC layer 8 / adhesive layer 3 / glass 9.

  The haze of the test piece was measured using a haze meter (trade name: HM-150, manufactured by Murakami Color Research Laboratory Co., Ltd.) in an environment of 23 ° C. and 50% RH. And it confirmed that haze (initial haze) was 2.0% or less.

Next, the test piece was stored in an environment of 60 ° C. and 95% RH (in a moist heat environment) for 500 hours, and then taken out in an environment of 23 ° C. and 50% RH. Measurements were similarly made and evaluated according to the following criteria.
A: Haze of test piece immediately after removal is less than 2.0% (very good)
◯: The haze of the test piece immediately after removal is 2.0% or more and less than 5.0% (good)
X: Haze of test piece immediately after taking out is 5.0% or more (defect)

<Dielectric constant>
A pressure-sensitive adhesive layer (a film obtained by peeling a silicone-treated PET film from a pressure-sensitive adhesive sheet) was sandwiched between a copper foil and an electrode, and a relative dielectric constant at a frequency of 100 kHz was measured by the following apparatus. Three samples were prepared for measurement, and the average of the measured values of these three samples was taken as the dielectric constant.
The relative dielectric constant of the pressure-sensitive adhesive layer at a frequency of 100 kHz was measured according to JIS K 6911 under the following conditions.
Measurement method: Capacity method (apparatus: using Agilent Technologies 4294A Precision Impedance Analyzer)
Electrode configuration: 12.1 mmφ, 0.5 mm thick aluminum plate Counter electrode: 3 oz copper plate Measurement environment: 23 ± 1 ° C., 52 ± 1% RH

前記皮脂膨潤度が１．１未満である場合は◎（耐皮脂性が極めて良好）であり、１．１以上１．２未満は○（耐皮脂性が良好）であり、１．２以上は×（耐皮脂性が不良）として評価した。

When the degree of sebum swelling is less than 1.1, it is ◎ (very good sebum resistance), 1.1 or more but less than 1.2 is ◯ (good sebum resistance), and 1.2 or more Evaluation was made as x (poor sebum resistance).

In Table 12,
BA is butyl acrylate;
2EHA is 2-ethylhexyl acrylate;
ICA is isocetyl acrylate;
NK-ISA is isostearyl acrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.);
ISTA is isostearyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.);
NVP is N-vinyl-2-pyrrolidone;
HBA is 4-hydroxybutyl acrylate;
TMPTA indicates trimethylolpropane triacrylate.

DESCRIPTION OF SYMBOLS 1 Capacitive touch panel 2 Decorative panel 3 Adhesive layer for transparent conductive film 4 Transparent conductive film 5 Hard coat film 6 Transparent conductive thin film: ITO layer 7 Base material layer 8 Functional layer (clear hard coat layer)
9 Glass

Claims (8)

A transparent conductive film pressure-sensitive adhesive layer applied to the functional layer of the transparent conductive film having a transparent conductive thin film on one side of the transparent plastic film substrate and a functional layer on the other side,
The pressure-sensitive adhesive layer includes a monofunctional monomer component containing 30 to 75% by weight of an alkyl (meth) acrylate having an alkyl group having 10 to 24 carbon atoms at an ester terminal and 20 to 50% by weight of a cyclic nitrogen-containing monomer. A pressure-sensitive adhesive layer for a transparent conductive film, obtained from a pressure-sensitive adhesive containing a (meth) acrylic polymer obtained by polymerizing a monomer component.   The pressure-sensitive adhesive layer for a transparent conductive film according to claim 1, wherein the monofunctional monomer component is a monomer component further containing 1% by weight or more of a hydroxyl group-containing monomer.   The monofunctional monomer component is further at least one selected from alkyl (meth) acrylates having an alkyl group having 1 to 9 carbon atoms at the ester end and alkyl (meth) acrylates having a cyclic alkyl group at the ester end The pressure-sensitive adhesive layer for a transparent conductive film according to claim 1, wherein the pressure-sensitive adhesive layer is a monomer component containing 0.5% by weight or more.   The transparent conductive material according to claim 1, wherein the monomer component further contains 3 parts by weight or less of a polyfunctional monomer with respect to 100 parts by weight of the monofunctional monomer component. Film adhesive layer.   The pressure-sensitive adhesive layer for a transparent conductive film according to any one of claims 1 to 4, wherein a relative dielectric constant at a frequency of 100 kHz is 3.5 or less.   The pressure-sensitive adhesive layer for a transparent conductive film according to any one of claims 1 to 5, wherein the gel fraction is 20 to 98% by weight.   The transparent conductive film according to any one of claims 1 to 6, wherein the transparent conductive film has a transparent conductive thin film on one side and a functional layer on the other side of the transparent conductive film. A transparent conductive film with an adhesive layer, wherein an adhesive layer for an adhesive film is provided.   A touch panel comprising at least one transparent conductive film with an adhesive layer according to claim 7.

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