TW201540794A - Adhesive agent and adhesive sheet - Google Patents

Abstract

Provided are: an adhesive agent to be used between two transparent conductive films or between a transparent conductive film and a covering material in a capacitive touch panel, the adhesive agent having a refractive index of 1.45 to 1.54 and a storage modulus at 80 DEG C of 0.02 to 0.10 MPa and including no component that has a carboxyl group; and an adhesive sheet (1) that includes an adhesive layer (11) composed of the adhesive agent. The adhesive agent and adhesive sheet (1) can make a circuit pattern of the transparent conductive film less visible, have excellent step conformability, and do not adversely affect the transparent conductive film with a carboxyl group.

Description

Adhesive and adhesive sheet

The present invention relates to an adhesive and an adhesive sheet which can be used for a touch panel or the like.

In recent years, in various mobile electronic devices such as smart phones and tablet computers, the use of a capacitive touch panel as a display has been increasing.

The capacitance type touch panel has a plurality of configurations. As a typical example, a display module including a liquid crystal module and a first thin film sensor laminated via an adhesive may be exemplified. The second thin film sensor is laminated on the first thin film sensor via an adhesive; and the cover material is laminated on the second thin film sensor via an adhesive.

Here, the frame-shaped printed layer may exist as a step on the display module side of the cover material. If the adhesive layer does not follow the step, the adhesive layer will float near the step, thereby causing light reflection loss. Therefore, step adhesion follow-up is required for the above adhesive layer.

On the other hand, in general, the above-described thin film sensor is composed of a base film and a transparent conductive film made of patterned tin-doped indium oxide (ITO). Here, if the adhesive of the adhesive layer in contact with the transparent conductive film contains a hydroxy acid (carboxyl group), the transparent conductive film is corroded or the resistance value of the transparent conductive film is changed. problem.

Further, in the touch panel having the transparent conductive film patterned as described above, there is a problem of so-called pattern visualization which affects the appearance due to the circuit pattern of the transparent conductive film being seen. When the touch panel is placed at a high temperature, there is a tendency to particularly cause this problem.

In order to solve the above problem of pattern visualization, Patent Document 1 proposes an adhesive which defines a storage elastic modulus at 23 ° C, and Patent Document 2 proposes to adhere a storage elastic modulus at 120 ° C and an adhesive force. Agent. Further, Patent Document 3 proposes an adhesive layer which uses a propylene-based adhesive composition containing a predetermined amount of a propylene-based polymer and a styrene-based oligomer, and defines a refractive index and a haze.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2012-128629

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2012-238467

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2013-116992

However, the adhesives of Patent Documents 1 to 3 do not sufficiently satisfy the effects of both the pattern visualization suppressing performance and the step followability. Further, since the propylene-based polymer of the adhesive used in the examples of Patent Document 2 has acrylic acid as a constituent monomer, it adversely affects the transparent conductive film.

The present invention has been made in view of the actual situation as described above. In the touch panel of the electrostatic capacitance type, an adhesive and an adhesive sheet which can make the circuit pattern of the transparent conductive film inconspicuous, have excellent step followability, and do not adversely affect the transparent conductive film by the carboxyl group.

In order to achieve the above object, a first invention of the present invention provides an adhesive which is used in a capacitive touch panel between two transparent conductive films or between a transparent conductive film and a cover material, wherein a refractive index It is 1.45 to 1.54, and has a storage elastic modulus of 0.02 to 0.10 MPa at 80 ° C, and does not contain a component having a carboxyl group (Invention 1).

According to the invention (Invention 1), by specifying the refractive index and the storage elastic modulus as described above, the circuit pattern of the transparent conductive film can be made inconspicuous in the capacitive touch panel, in particular, the touch panel is placed at 80 ° C. It can also exert its effects when it is at a high temperature. In addition, by setting the refractive index and the storage elastic modulus as described above, it is also excellent in the step-followability with respect to the printing step difference of the cover material. Further, since the component having a carboxyl group is not contained, it is possible to suppress corrosion of the transparent conductive film or change the resistance value of the transparent conductive film.

In the above invention (Invention 1), the adhesive is preferably formed by crosslinking an adhesive composition containing a (meth) acrylate copolymer (A) and a crosslinking agent (B). In the (meth) acrylate copolymer (A), the monomer unit constituting the polymer contains 5 to 30% by mass of the monomer having a hydroxyl group, and the glass transition temperature of the homopolymer is 70 ° C. The hard monomer of the above aromatic ring is 5 to 40% by mass, and does not contain a monomer having a carboxyl group (Invention 2).

In the above invention (Invention 2), the aforementioned (meth) acrylate The weight average molecular weight of the copolymer (A) is preferably from 200,000 to 1,000,000 (Invention 3).

In the above invention (Invention 2, 3), the (meth) acrylate copolymer (A) as a monomer unit constituting the polymer, that is, the hard monomer, is selected from the group consisting of methyl methacrylate and acrylic acid. At least one of the group consisting of borneol ester and propylene morpholine is preferred (Invention 4).

In the above invention (Inventions 2 to 4), it is preferred that the pressure-sensitive adhesive further contains a decane coupling agent (C) (Invention 5).

According to a second aspect of the present invention, there is provided an adhesive sheet for use in a subsequent one of two transparent conductive films in a capacitive touch panel or a transparent conductive film and a cover material, wherein two peeling sheets are included and The adhesive layer sandwiched by the peeling sheet in contact with the peeling surface of the two release sheets, the adhesive layer is composed of the above-mentioned adhesive (Inventions 1 to 5) (Invention 6).

In the above invention (Invention 6), it is preferred that the thickness of the pressure-sensitive adhesive layer is from 10 to 400 μm (Invention 7).

In the above invention (Inventions 6, 7), the adhesive layer is laminated on the surface of the layered body on the substrate made of a polyethylene terephthalate film having a thickness of 100 μm, and adhered to the surface of the layer of the adhesive layer. In the case of soda lime glass, it is preferred that the laminate has an adhesion to the soda lime glass of 5 to 50 N/25 mm (Invention 8).

According to the adhesive of the present invention and the adhesive layer of the adhesive sheet, the circuit pattern of the transparent conductive film can be made inconspicuous in the electrostatic capacitance type touch panel, and in particular, when the touch panel is placed at a high temperature of 80 ° C or the like, the touch panel can also be used. effect fruit. Further, the adhesive of the present invention and the adhesive layer of the pressure-sensitive adhesive sheet are excellent in step-followability, and since the component having a carboxyl group is not contained, corrosion of the transparent conductive film or change in the resistance value of the transparent conductive film can be suppressed.

1‧‧‧Adhesive film

11‧‧‧Adhesive layer

12a, 12b‧‧‧ peeling film

2‧‧‧ touch panel

3‧‧‧Display body module

4‧‧‧Adhesive layer

5a‧‧‧1st film sensor

5b‧‧‧2nd film sensor

51‧‧‧Substrate film

52‧‧‧Transparent conductive film

6‧‧‧Cover materials

7‧‧‧Printing layer

Fig. 1 is a cross-sectional view showing an adhesive sheet according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view showing a configuration example of a touch panel.

Hereinafter, embodiments of the present invention will be described.

[adhesive]

The adhesive of the present embodiment has a refractive index of 1.45 to 1.54, a storage elastic modulus at 80 ° C of 0.02 to 0.10 MPa, and does not contain a component having a carboxyl group. The adhesive is used between two transparent conductive films or between a transparent conductive film and a cover material in a capacitive touch panel.

The refractive index of the adhesive of the present embodiment and the storage elastic modulus at 80 ° C are within the above range, whereby the circuit pattern of the transparent conductive film can be made inconspicuous (not easily observed) in the capacitive touch panel. In particular, the touch panel can also exert its effect when placed at a high temperature such as 80 °C. Further, the refractive index of the adhesive of the present embodiment and the storage elastic modulus at 80 ° C are within the above range, and thus the step followability is also excellent. Therefore, even if the adhesive layer composed of the adhesive is adhered to the cover material having the step formed by the printed layer or the like, voids or bubbles are less likely to occur between the step and the adhesive layer. Further, even when the laminated body is placed at a high temperature such as 80 ° C, generation of bubbles or the like in the vicinity of the step can be prevented. Further, the adhesive of the present embodiment does not contain a component having a carboxyl group, and therefore It is possible to suppress corrosion of the transparent conductive film or change in the resistance value of the transparent conductive film.

If the refractive index of the adhesive is less than 1.45, the circuit pattern of the transparent conductive film is easily seen. On the other hand, if the refractive index of the adhesive exceeds 1.54, the step followability deteriorates. Further, if the storage elastic modulus at 80 ° C is less than 0.02 MPa, the circuit pattern of the transparent conductive film is easily seen, and in particular, it is clearly visible when placed at a high temperature such as 80 ° C. On the other hand, if the storage elastic modulus of the adhesive at 80 ° C exceeds 0.10 MPa, the step followability deteriorates.

From the above point of view, the refractive index of the adhesive is preferably 1.46 to 1.52, and particularly preferably 1.47 to 1.50. Further, the storage elastic modulus of the adhesive at 80 ° C is preferably 0.015 to 0.09 MPa, more preferably 0.02 to 0.07 MPa.

In addition, the refractive index in this specification is a value measured using the Abbe refractometer based on JIS K0062-1992. Further, the storage elastic modulus at 80 ° C is a value measured by a torsional shearing method shown in a test example described later.

The adhesive according to the present embodiment may be any one that satisfies the above properties, but an adhesive composition containing a (meth) acrylate copolymer (A), a crosslinking agent (B), and a decane coupling agent (C). (Hereinafter, it may be referred to as "adhesive composition P".) It is preferred to carry out crosslinking by forming an adhesive. In the above (meth) acrylate copolymer (A), it is a monomer unit constituting the polymer. 5 to 30% by mass of a monomer having a hydroxyl group (hydroxyl-containing monomer), and 5 to 40% of a hard monomer having no aromatic ring having a glass transition temperature (Tg) of 70 ° C or more as a homopolymer %, and does not contain a monomer having a carboxyl group. According to the adhesive, the above physical properties (refractive index and storage elastic modulus) can be satisfied. In the present specification, (meth)acrylic means both acrylic acid and methacrylic acid. Other similar terms are the same.

(1) (meth) acrylate copolymer (A)

The adhesive composition P preferably contains a (meth) acrylate copolymer (A) as a main adhesive. In the (meth) acrylate copolymer (A), the content of the hydroxyl group-containing monomer and the above hard monomer is within the above range, whereby the adhesive composition containing the (meth) acrylate copolymer (A) is used. The obtained adhesive easily satisfies the aforementioned refractive index and storage elastic modulus.

Further, the adhesive obtained from the adhesive composition P of the (meth) acrylate copolymer (A) having a content of the hydroxyl group-containing monomer in the above range is set under high temperature and high humidity conditions (for example, 85 ° C, 85). The whitening at the time of returning to normal temperature and normal humidity after 72 hours) under the condition of %RH is suppressed, that is, it is excellent in resistance to moist heat whitening. When the (meth) acrylate copolymer (A) contains a hydroxyl group-containing monomer as a monomer unit in the above amount, a predetermined amount of a hydroxyl group remains in the obtained adhesive. The hydroxyl group is a hydrophilic group. Therefore, if the above-mentioned quantitative hydrophilic group is present in the adhesive, even if the adhesive is placed under high temperature and high humidity conditions, under the high temperature and high humidity conditions, it is immersed in the adhesive. The compatibility of moisture is also good, and as a result, whitening of the adhesive is suppressed.

In the (meth) acrylate copolymer (A), when the content of the hydroxyl group-containing monomer as a monomer unit is less than 5% by mass, the wet heat whitening resistance may be lowered, and on the other hand, if the hydroxyl group-containing monomer is contained When the content is more than 30% by mass, the adhesion to the object may be lowered, the durability may be lowered, or the desired adhesive force may not be obtained.

Further, in the (meth) acrylate copolymer (A), if the content of the hard monomer as a monomer unit is less than 5% by mass, the refractive index and storage elastic modulus of the adhesive may be lower than the above range. On the other hand, if hard When the content of the monomer exceeds 40% by mass, the step followability is lowered or the desired adhesive force cannot be obtained.

From the above viewpoints, it is preferable that the (meth) acrylate copolymer (A) contains 5 to 30% by mass of the hydroxyl group-containing monomer as a monomer unit constituting the polymer, and particularly preferably 10 to 25% by mass. . In the (meth) acrylate copolymer (A), the monomer unit constituting the polymer preferably contains 5 to 50% by mass of the hard monomer, and more preferably 10 to 30% by mass.

The hydroxyl group-containing monomer may, for example, be 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate or (meth)acrylic acid. 2-hydroxybutyl ester, 3-hydroxybutyl (meth)acrylate, hydroxyalkyl (meth)acrylate such as 4-hydroxybutyl (meth)acrylate. Among them, from the viewpoint of reactivity with a hydroxyl group and a crosslinking agent (B) and copolymerization with other monomers in the obtained (meth) acrylate polymer (A), (meth)acrylic acid 2- Hydroxyethyl ester is preferred. These may be used singly or in combination of two or more.

The hard monomer is a monomer not containing an aromatic ring, and the glass transition temperature obtained by polymerizing only the hard monomer is 70 ° C or higher, preferably 75 to 200 ° C, and particularly preferably 80 to 180 ° C. good.

The hard monomer is preferably a propylene-based monomer, and examples thereof include methyl methacrylate (Tg 105 ° C), isobornyl acrylate (Tg 94 ° C), isobornyl methacrylate (Tg 180 ° C), and propylene. Anthraquinone (Tg 145 ° C), adamantyl acrylate (Tg 115 ° C), adamantyl methacrylate (Tg 141 ° C), dimethyl methacrylate (Tg 89 ° C), acrylamide (Tg 165 ° C) and the like. These may be used singly or in combination of two or more.

Among the above hard monomers, in particular, methyl methacrylate, isobornyl acrylate and propylene morpholine are preferred. That is, the (meth) acrylate copolymer (A) contains a group selected from methyl methacrylate, isobornyl acrylate, and propylene morpholine selected from the above-mentioned hard monomers constituting the monomer unit of the polymer. At least one of them is preferred.

In the (meth) acrylate polymer (A), the monomer unit constituting the polymer does not contain a carboxyl group-containing monomer. Thereby, even if the obtained adhesive adheres to the transparent conductive film, the trouble caused by the acid can be suppressed. For example, it is possible to suppress corrosion of the transparent conductive film or change in the resistance value of the transparent conductive film.

Here, "the component having no carboxyl group" and "the monomer having no carboxyl group" means that the component or monomer having a carboxyl group is not actually contained, except that the carboxyl group-containing component or monomer is not contained at all, The degree of corrosion of the transparent conductive film due to the carboxyl group is allowed to contain a carboxyl group-containing component or a monomer. Specifically, the (meth) acrylate polymer (A) is preferably contained in an amount of 0.1% by mass or less as a monomer unit, and is contained in an amount of 0.01% by mass or less.

In the (meth) acrylate copolymer (A), as a monomer unit constituting the polymer, an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms (except for the aforementioned hard monomer) Other than) is preferred. Thereby, the obtained adhesive can exhibit better adhesion.

The alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group may, for example, be methyl (meth)acrylate, ethyl (meth)acrylate or propyl (meth)acrylate, ( N-butyl methacrylate, n-amyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate Ester, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, tetradecyl (meth)acrylate, sixteen (meth)acrylate An alkyl ester, octadecyl (meth)acrylate, and the like. Among them, from the viewpoint of further improving the adhesion, a (meth) acrylate having an alkyl group having 2 to 8 carbon atoms is preferred, n-butyl (meth) acrylate and 2-ethyl (meth) acrylate. Hexyl ester is especially preferred. Further, these materials may be used singly or in combination of two or more.

In the (meth) acrylate copolymer (A), as a monomer unit constituting the polymer, the alkyl (meth) acrylate having an alkyl group having 2 to 20 carbon atoms is 10 to 90% by mass. Preferably, it is preferably from 20 to 85% by mass, and further preferably from 30 to 80% by mass.

In the (meth) acrylate copolymer (A), a monomer which can increase the refractive index of the obtained adhesive may be contained as a monomer unit constituting the polymer (hereinafter, sometimes referred to as "high refraction" Rate monomer".).

The monomer having an aromatic ring is preferable as the high refractive index monomer, and examples thereof include an aromatic monomer having one or more aromatic rings, a monomer having a polycyclic aromatic skeleton, and the like. Examples of the aromatic monomer containing one aromatic ring include benzyl (meth)acrylate, 2-phenoxyethyl acrylate, nonylphenoxy polyethylene glycol acrylate, and (methyl). Styrene acrylate and the like.

The aromatic monomer containing two or more aromatic rings may, for example, be a biphenyl group-containing monomer or a bisphenol A type monomer, and a biphenyl group-containing monomer is preferable from the viewpoint of handling. As the biphenyl group-containing monomer, a biphenyl group-containing acrylate is preferred. As such a biphenyl-containing monomer, ethoxylated o-phenylbenzene is exemplified. Phenolic acrylate, o-biphenyl (meth) acrylate, and the like.

The monomer having a polycyclic aromatic skeleton may, for example, be a naphthalene skeleton, an anthracene skeleton, a triphenylene skeleton, a benzofluorene skeleton, a naphthacene skeleton, a rhombo skeleton, an anthracene skeleton, a pentacene skeleton, and a hexacene. Monomers such as skeleton, heptabenzene skeleton, halobenzene skeleton, and kekuleene skeleton. From the viewpoint of handling, a monomer having a naphthalene skeleton or an anthracene skeleton as a polycyclic aromatic skeleton is preferable, and among them, a monomer having a naphthalene skeleton is more preferable.

The monomer having a naphthalene skeleton may, for example, be 1-naphthyl (meth) acrylate, 2-naphthyl (meth) acrylate or 2-(1-naphthyloxy) ethyl acrylate (4). -Methoxy-naphthylene)-1-acrylate, vinyl naphthalene, and the like.

Among the above high refractive index monomers, benzyl (meth) acrylate and ethoxylated o-phenyl phenol acrylate are particularly preferable from the viewpoint of exhibiting a high refractive index and obtaining desired adhesive applicability and handleability. . Further, the above-mentioned high refractive index monomers may be used alone or in combination of two or more.

When the (meth) acrylate copolymer (A) contains a high refractive index monomer as a monomer unit constituting the polymer, the content thereof is preferably from 1 to 30% by mass, more preferably from 2 to 20% by mass. good.

The (meth) acrylate copolymer (A) may contain other monomers as a monomer unit constituting the polymer, as needed. As the other monomer, a monomer which does not contain a reactive functional group without impairing the action of the hydroxyl group-containing monomer is preferred. The other monomer may, for example, be an alkoxyalkyl (meth)acrylate such as methoxyethyl (meth)acrylate or ethoxyethyl (meth)acrylate or a cyclohexyl (meth)acrylate. (meth) acrylate having an aliphatic ring such as ester, N,N-dimethylaminoethyl (meth) acrylate, (meth) propylene (meth)acrylate having a non-crosslinkable tertiary amino group such as acid-N,N-dimethylaminopropyl ester, vinyl acetate, styrene or the like. These may be used singly or in combination of two or more.

The polymerization state of the (meth) acrylate copolymer (A) may be a random copolymer or a block copolymer.

The (meth) acrylate copolymer (A) preferably has a weight average molecular weight of 200,000 to 1,000,000, more preferably 300,000 to 900,000, and more preferably 400,000 to 800,000. In addition, the weight average molecular weight in this specification is a polystyrene conversion value measured by the gel permeation chromatography (GPC) method.

Since the weight average molecular weight of the (meth) acrylate copolymer (A) is within the above range, the obtained adhesive easily satisfies the aforementioned storage elastic modulus.

Further, in the adhesive composition P, the (meth) acrylate copolymer (A) may be used alone or in combination of two or more.

(2) Crosslinking agent (B)

When the adhesive composition P is crosslinked, the crosslinking agent (B) is reacted with a hydroxyl group derived from a hydroxyl group-containing monomer constituting the (meth) acrylate copolymer (A). Thereby, the structure in which the (meth) acrylate copolymer (A) is crosslinked by the crosslinking agent (B) is formed.

The crosslinking agent (B) may be reacted with a reactive group (hydroxy group of a hydroxyl group-containing monomer as a monomer unit) of the (meth) acrylate copolymer (A), for example, isocyanate crosslinking. Agent, epoxy crosslinking agent, amine crosslinking agent, melamine crosslinking agent, nitrogen-acrylic ring crosslinking agent, hydrazine crosslinking agent, aldehyde crosslinking agent, oxazoline crosslinking agent, metal Alkoxide system crosslinker, metal chelate A crosslinking agent, a metal salt crosslinking agent, an ammonium salt crosslinking agent, etc. Among the above substances, an isocyanate crosslinking agent which is excellent in reactivity with a hydroxyl group is preferred. Further, the crosslinking agent (B) may be used alone or in combination of two or more.

The isocyanate crosslinking agent is a compound containing at least a polyisocyanate compound. The polyisocyanate compound may, for example, be an aromatic polyisocyanate such as toluene diisocyanate, diphenylmethane diisocyanate or xylene diisocyanate, or an aliphatic polyisocyanate such as hexamethylene diisocyanate or isophorone diisocyanate. An alicyclic polyisocyanate such as hydrogenated diphenylmethane diisocyanate, and the biuret and isocyanurate of the substance, in addition, ethylene glycol, propylene glycol, neopentyl glycol, and trishydroxyl The reactant of a low molecular weight active hydrogen compound such as propane or castor oil is also an adduct or the like. Among them, trimethylolpropane-modified aromatic polyisocyanate is preferred from the viewpoint of reactivity with a hydroxyl group, trimethylolpropane-modified toluene diisocyanate, and trimethylolpropane-modified xylene-diene Isocyanates are especially preferred.

The content of the crosslinking agent (B) in the adhesive composition P is preferably 0.01 to 2 parts by mass based on 100 parts by mass of the (meth) acrylate copolymer (A), and particularly preferably 0.05 to 1 part by mass, 0.1 to 0.1% by weight. 0.5 parts by mass is further preferred. If the content of the crosslinking agent (B) is within the above range, the obtained adhesive can easily satisfy the aforementioned refractive index and storage elastic modulus.

(3) decane coupling agent (C)

The adhesive composition P preferably contains a decane coupling agent (C) from the viewpoint of improving the adhesion of the obtained adhesive. As the decane coupling agent (C), an organic ruthenium compound having at least one alkoxyalkylene group in the molecule is preferable because it has good compatibility with the (meth) acrylate copolymer (A) and has light transmittance.

Examples of the decane coupling agent (C) include a fluorene compound containing a polymerizable unsaturated group such as vinyl trimethoxy decane, vinyl triethoxy decane or methacryl oxime, and 3-glycidyl ether C. Epoxy-based oxime compound such as trimethoxy decane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, 3-mercaptopropyltrimethoxydecane, 3-mercaptopropyltriethoxy A fluorenyl-containing hydrazine compound such as decane or 3-mercaptopropyldimethoxymethyl decane, 3-aminopropyltrimethoxydecane, N-(2-aminoethyl)-3-aminopropyltrimethoxydecane An aminoguanidine-containing compound such as N-(2-aminoethyl)-3-aminopropylmethyldimethoxydecane, 3-chloropropyltrimethoxydecane, 3-isocyanatepropyltriethoxydecane, Or at least one condensate of an alkyl group-containing compound such as methyltriethoxydecane, ethyltriethoxydecane, methyltrimethoxydecane or ethyltrimethoxydecane. These may be used alone or in combination of two or more.

The content of the decane coupling agent (C) in the adhesive composition P is preferably 0.01 to 1 part by mass, more preferably 0.05 to 0.5 part by mass, based on 100 parts by mass of the (meth) acrylate copolymer (A), and 0.1 or more. ~0.3 parts by mass is further preferred.

(4) Various additives

In the adhesive composition P, various additives generally used as a propylene-based adhesive can be added as needed, for example, a refractive index adjuster, an antistatic agent, a tackifier, an antioxidant, an ultraviolet absorber, a light stabilizer, and softening. Agents, fillers, etc.

The refractive index adjusting agent may, for example, be benzyl benzoate, diphenyl sulfide, triphenyl phosphate, n-butyl phthalate, diphenyl phthalate, biphenyl or diphenylmethane. , tricresyl phosphate, diphenyl sulfoxide, and the like.

When the adhesive composition P contains a refractive index adjuster, The content thereof is preferably 1 to 30 parts by mass, more preferably 5 to 20 parts by mass, per 100 parts by mass of the acrylate copolymer (A).

(5) Manufacture of adhesive composition

Producing a (meth) acrylate copolymer (A), adding a crosslinking agent (B) to the obtained (meth) acrylate copolymer (A), and adding a decane coupling agent (C) and an additive as needed, Thereby, the adhesive composition P can be manufactured.

The (meth) acrylate copolymer (A) can be produced by polymerizing a mixture of monomer units constituting the polymer by a usual radical polymerization method. The polymerization of the (meth) acrylate copolymer (A) can be carried out by a solution polymerization method or the like using a polymerization initiator as needed. The polymerization solvent may, for example, be ethyl acetate, n-butyl acetate, n-isobutyl acetate, toluene, acetone, hexane or methyl ethyl ketone, or two or more kinds thereof may be used in combination.

The polymerization initiator may, for example, be an azo compound or an organic peroxide, or two or more kinds thereof may be used in combination. As the azo compound, for example, 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane- 1-carboxonitrile, 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile ), 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxyl) Propionitrile, 2,2'-azobis[2-(2-imidazolin-2-yl)propane, and the like.

The organic peroxide may, for example, be benzoic acid benzoate, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate or di-N-propyl peroxydicarboxylate. Carbonate, bis(2-ethoxyethyl)peroxydicarbonate, tert-butyl peroxy neodecanoate, tert-butyl peroxypivalate, (3,5,5-trimethylhexyl) Peroxide, dipropene peroxide, diethylperoxide peroxide, and the like.

Further, in the above polymerization process, the weight average molecular weight of the obtained polymer can be adjusted by blending a chain transfer agent such as 2-mercaptoethanol.

After obtaining the (meth) acrylate copolymer (A), a crosslinking agent (B) is added to the (meth) acrylate copolymer (A) solution, and a decane coupling agent (C), a diluent solvent, and the like are added as needed. The additive is obtained by sufficiently mixing to obtain an adhesive composition P (coating solution) diluted with a solvent.

As the diluent solvent, for example, an aliphatic hydrocarbon such as hexane, heptane or cyclohexane, an aromatic hydrocarbon such as toluene or xylene, or a chlorinated hydrocarbon such as dichloromethane or dichloroethane, methanol or ethanol can be used. , propanol, butanol, 1-methoxy-2-propanol and other alcohols, acetone, methyl ethyl ketone, 2-pentanone, isophorone, cyclohexanone and other ketones, ethyl acetate, butyl citrate An ester such as an ester or a cellosolve such as an ethyl cellosolve is a solvent.

The concentration of the concentration of the coating solution thus prepared is not particularly limited as long as it is within the range that can be applied, and can be appropriately selected depending on the situation. For example, it is diluted so that the concentration of the adhesive composition P becomes 10 to 60% by mass. Further, when the coating solution is obtained, the addition of a diluent solvent or the like is not a requirement, and if the adhesive composition P is a coatable viscosity or the like, the diluent solvent may not be added. In this case, the adhesive composition P is a coating solution in which a polymerization solvent of the (meth)acrylate polymer (A) is directly used as a diluent solvent.

(6) Manufacture of adhesives

The adhesive of the present embodiment is preferably formed by crosslinking the adhesive composition P. The crosslinking of the adhesive composition P is usually carried out by heat treatment. In addition, the heat treatment can be used as the heat treatment by volatilizing the diluent solvent or the like of the adhesive composition P.

When the heat treatment is performed, the heating temperature is preferably from 50 to 150 ° C, and particularly preferably from 70 to 120 ° C. Further, the heating time is preferably from 30 seconds to 10 minutes, and particularly preferably from 50 seconds to 2 minutes. After the heat treatment, if necessary, it may be set to a normal temperature (for example, 23 ° C, 50% RH) and a curing period of about 1 to 2 weeks. When the curing period is required, the adhesive is formed after the passage of the curing period, and the adhesive is formed after the heat treatment is completed without the need for the curing period.

By the above heat treatment (and curing), the (meth) acrylate copolymer (A) is crosslinked well via the crosslinking agent (B), and the physical properties described above can be exhibited.

[adhesive sheet]

As shown in Fig. 1, the adhesive sheet 1 of the present embodiment is sandwiched between the two release sheets 12a and 12b and the release sheets of the two release sheets 12a and 12b so as to be in contact with the release surfaces of the two release sheets 12a and 12b. The adhesive layer 11 in 12b is composed. In addition, the peeling surface of the peeling sheet in this specification is the surface which has the peeling property in the peeling sheet, and the surface which carried out the peeling process, and the surface which shows the peeling-

(1) Adhesive layer

The adhesive layer 11 is preferably composed of the above-mentioned adhesive, and is preferably composed of an adhesive formed by crosslinking the adhesive composition P.

The thickness of the adhesive layer 11 (value measured based on JIS K7130) depends on the height of the step, preferably 10 to 400 μm, more preferably 20 to 300 μm, and further preferably 25 to 250 μm. Since the thickness of the adhesive layer 11 is 10 μm or more, good step followability can be exerted, and due to the adhesive layer 11 Since the thickness is 400 μm or less, the workability is good. Further, the adhesive layer 11 may be formed in a single layer or may be formed by laminating a plurality of layers.

(2) peeling sheet

As the release sheets 12a and 12b, for example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, or a poly pair can be used. Ethylene phthalate film, polyethylene naphthalene diene film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene/(meth)acrylic copolymer film , an ethylene/(meth) acrylate copolymer film, a polystyrene film, a polycarbonate film, a polyimide film, a fluororesin film, or the like. Further, a crosslinked film of these materials can also be used. In addition, a laminated film of these materials may also be used.

The release surface of the release sheets 12a and 12b (particularly the surface in contact with the adhesive layer 11) is preferably subjected to a release treatment. The release agent to be used for the release treatment may, for example, be a release agent such as an alkyd type, an anthrone type, a fluorine type, an unsaturated polyester type, a polyolefin type, or a wax type. In the release sheets 12a and 12b, one of the release sheets is a heavy release type release sheet having a large peeling force, and the other release sheet is preferably a light release type release sheet having a small peeling force.

The thickness of the release sheets 12a and 12b is not particularly limited, and is usually about 20 to 150 μm.

(3) Manufacture of adhesive sheets

As a production example of the adhesive sheet 1, the coating liquid of the above-mentioned adhesive composition P is applied to the peeling surface of one of the release sheets 12a (or 12b), and heat treatment is performed to crosslink the adhesive composition P to form After coating the layer, peel the other side The peeling surface of the sheet 12b (or 12a) is superposed on the coating layer. In the case where a curing period is required, the coating layer is directly formed as the adhesive layer 11 when the curing period is not required in advance. Thereby, the above-mentioned adhesive sheet 1 can be obtained. The conditions regarding heat treatment and curing are as described above.

In another example of the production of the adhesive sheet 1, the coating liquid of the adhesive composition P is applied to the release surface of one of the release sheets 12a, and heat treatment is performed to crosslink the adhesive composition P to form a coating layer. A release sheet 12a with a coating layer was obtained. Then, the coating liquid of the adhesive composition P is applied onto the peeling surface of the other release sheet 12b, and heat-treated to crosslink the adhesive composition P to form a coating layer, thereby obtaining a coated layer. The sheet 12b is peeled off. Then, the release sheet 12a with the coating layer and the release sheet 12b with the coating layer are bonded so that the two coating layers are in contact with each other. In the case where a curing period is required, the coating layer of the above-mentioned laminated layer directly becomes the adhesive layer 11 when the curing period is not required in advance. Thereby, the above-mentioned adhesive sheet 1 can be obtained. According to this production example, even when the adhesive layer 11 is thick, it can be stably produced.

As a method of applying the coating liquid of the above-mentioned adhesive composition P, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used. .

(4) Adhesion

The adhesive layer 11 is laminated on the surface of the adhesive layer 11 of the laminate on the substrate made of a polyethylene terephthalate film having a thickness of 100 μm, and is adhered to an indium oxide doped with tin (ITO). In the case of the transparent conductive film of the transparent conductive film constituting the transparent conductive film, the adhesion of the laminate to the transparent conductive film is preferably 5 to 80 N/25 mm, more preferably 10 to 70 N/25 mm. 15~50N/25mm is further preferred. Since the adhesive force is within the above range, the constituent components of the touch panel can be reliably followed.

In addition, the term "adhesive force" as used herein refers to an adhesion measured by a 180° peeling method based on JIS Z0237:2009, and the measurement sample is set to have a width of 25 mm and a length of 100 mm, and the measurement sample is placed on the object. After sticking at 0.5 MPa and 50 ° C for 20 minutes and pasting, it was allowed to stand under normal pressure, 23 ° C, and 50% RH for 24 hours, and then measured at a peeling speed of 300 mm/min.

(5) Use of adhesive sheets

By using the above-described adhesive sheet 1, for example, the electrostatic capacitance type touch panel 2 shown in Fig. 2 can be manufactured. The touch panel 2 is configured to include a display body module 3; the first film sensor 5a is laminated on the display body module 3 via the adhesive layer 4; and the second film sensor 5b is laminated on the adhesive layer 11 The cover film 6 is laminated on the first film sensor 5b via the adhesive layer 11 on the first film sensor 5a.

The two adhesive layers 11 of the touch panel 2 are the adhesive layer 11 of the adhesive sheet 1.

Examples of the display body module 3 include a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module, and electronic paper.

The adhesive layer 4 can be formed by the adhesive layer 11 of the above-mentioned adhesive sheet 1, or can be formed by other adhesives or adhesive sheets. In the latter case, examples of the adhesive constituting the adhesive layer 4 include a propylene-based adhesive, a rubber-based adhesive, an anthrone-based adhesive, a urethane-based adhesive, a polyester-based adhesive, and a polyethylene. An ether-based adhesive or the like is preferred, and a propylene-based adhesive is preferred.

The first thin film sensor 5a and the second thin film sensor 5b are generally composed of a base film 51 and a patterned transparent conductive film 52, respectively. The base film 51 is not particularly limited, and for example, a polyethylene terephthalate film, a polycarbonate film, a polymethyl methacrylate film, a polycycloolefin film, a polyolefin film, or a cellulose triacetate film can be used. .

Examples of the transparent conductive film 52 include metals such as platinum, gold, silver, and copper, oxides such as tin oxide, indium oxide, cadmium oxide, zinc oxide, and zinc oxide, tin-doped indium oxide (ITO), and zinc oxide. Doped indium oxide, fluorine-doped indium oxide, antimony-doped tin oxide, fluorine-doped tin oxide, aluminum-doped zinc oxide and other composite oxides, chalcogenide, lanthanum hexaboride, titanium nitride, titanium carbide, etc. An oxidizing compound or the like, which is preferably composed of tin-doped indium oxide (ITO).

Usually, the transparent conductive film 52 of the first thin film sensor 5a and the transparent conductive film 52 of the second thin film sensor 5b constitute one circuit pattern in the X-axis direction, and the other constitutes a circuit pattern in the Y-axis direction.

In the second embodiment, the transparent conductive film 52 of the first thin film sensor 5a of the present embodiment is located on the upper side of the first thin film sensor 5a (on the side of the cover material 6), but the present invention is not limited thereto, and may be located at the first The lower side of the film sensor 5a (representing the module 3 side). In the second embodiment, the transparent conductive film 52 of the second thin film sensor 5b is located below the second thin film sensor 5b. However, the present invention is not limited thereto, and may be located on the upper side of the second thin film sensor 5b. .

The cover material 6 is usually made of a glass plate or a plastic plate. The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, bismuth-containing glass, yttrium aluminate glass acid, and lead glass. Boric acid glass, barium borate glass, and the like. The plastic plate is not particularly limited, and examples thereof include an acrylic plate made of polymethyl methacrylate or the like, a polycarbonate plate, and the like.

Further, on one or both sides of the glass plate or the plastic plate, a functional layer such as a hard coat layer, an antireflection layer, or an antiglare layer may be provided, and an optical component such as a hard coat film, an antireflection film, or an antiglare film may be laminated.

In the present embodiment, the cover material 6 has a step on the surface on the side of the adhesive layer 11, and specifically has a step formed by the presence or absence of the printed layer 7. The printed layer 7 is generally formed in a frame shape on the side of the adhesive layer 11 in the cover material 6.

The material constituting the printing layer 7 is not particularly limited, and a known material for printing can be used. The thickness of the printed layer 7, that is, the step height of 3 to 45 μm is preferable, 5 to 35 μm is more preferable, 7 to 25 μm is particularly preferable, and 7 to 15 μm is further preferable.

Further, the thickness (step height) of the printed layer 7 is preferably from 3 to 30% of the thickness of the adhesive layer 11, particularly preferably from 3.2 to 20%, and further preferably from 3.5 to 15%. As a result, the adhesive layer 11 satisfactorily follows the step formed by the printed layer 7, and it is possible to suppress the occurrence of floating, bubbles, and the like in the vicinity of the step.

An example of the method of manufacturing the touch panel 2 described above will be described below.

One of the release sheets 12a (or 12b) is peeled off from the adhesive sheet 1, and the exposed adhesive layer 11 is attached to the film sensor 5a so as to be in contact with the patterned transparent conductive film 52 of the film sensor 5a. Next, the other release sheet 12b (or 12a) is peeled off from the adhesive sheet 1, and the exposed adhesive layer 11 is attached to the film in contact with the patterned transparent conductive film 52 of the film sensor 5b. Sensor 5b. Thereby, a laminated body in which the thin film sensor 5a, the adhesive layer 11, and the thin film sensor 5b are laminated in this order can be obtained.

Next, the adhesive layer 4 provided on the release sheet is bonded to the surface of the laminate on the side of the thin film sensor 5a (the exposed surface of the base film 51 of the film sensor 5a). Further, an adhesive sheet 1 different from the above-described adhesive sheet 1 is prepared, and one of the release sheets 12a (or 12b) is peeled off from the adhesive sheet 1, and the exposed adhesive layer 11 is bonded to the laminated body in which the adhesive layer 4 is laminated. The surface on the opposite side of one side (the exposed surface of the base film 51 of the film sensor 5b).

Thereafter, the other release sheet 12b (or 12a) is peeled off from the other adhesive sheet 1, and the cover material 6 is attached to the exposed surface so that the printed layer 7 side of the cover material 6 comes into contact with the adhesive layer 11. Adhesive layer 11. Thereby, the cover material 6, the adhesive layer 11, the film sensor 5b, the adhesive layer 11, the film sensor 5a, the adhesive layer 4, and the peeling sheet can be obtained by laminating in order.

Finally, the release sheet is peeled off from the above-mentioned constituent body, and the exposed adhesive layer 4 is brought into contact with the display module 3 to bond the constituent body to the display module 3. Thereby, the touch panel 2 shown in FIG. 2 can be manufactured.

In the above-described process, when the adhesive layer 11 and the cover material 6 are bonded, since the adhesion layer 11 has excellent step followability, the gap formed by the printed layer 7 and the adhesive layer 11 are less likely to be voided. The adhesive layer 11 is capable of filling the step.

In the above touch panel 2, the adhesive layer 11 has a predetermined folding The transmittance and the storage elastic modulus are such that the circuit pattern of the transparent conductive film 52 is not conspicuous, and in particular, the touch panel 2 can be exerted at a high temperature such as 80 ° C. Further, in the touch panel 2 described above, the adhesion layer 11 has excellent step followability. Therefore, voids or air bubbles are less likely to be generated between the step formed by the printed layer 7 and the adhesive layer 11, and when the touch panel 2 is placed under high temperature and high humidity conditions, bubbles may be prevented from occurring in the vicinity of the step. . Further, in the touch panel 2, since the adhesive layer 11 does not contain a component having a carboxyl group, it is possible to suppress corrosion of the transparent conductive film 52 in contact with the adhesive layer 11, or to change the resistance value of the transparent conductive film 52. Further, when the adhesive layer 11 is formed by crosslinking the adhesive composition P, the adhesive layer 11 is excellent in moist heat whitening property, and the touch panel 2 is placed under high temperature and high humidity conditions to be restored. Whitening at normal temperature is suppressed. Further, in the case where the cover material 6 is a plastic plate, since the adhesive layer 11 has the aforementioned storage elastic modulus and has a cohesive force derived from the hard monomer in the (meth) acrylate copolymer (A), The foaming or bubble mixing (bubble) of the adhesive layer 11 due to degassing or the like which is generated from the cover material 6 is suppressed.

The embodiments described above are described in order to facilitate the understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design changes or equivalents falling within the technical scope of the invention.

For example, either one of the release sheets 12a and 12b in the adhesive sheet 1 may be omitted.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples, but the scope of the present invention is not limited to the examples and the like.

[Example 1]

1. Preparation of (meth) acrylate copolymer

Copolymerization of 30 parts by mass of butyl acrylate, 30 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of methyl methacrylate, and 20 parts by mass of 2-hydroxyethyl acrylate to prepare (meth) acrylate copolymerization (A). The molecular weight of the (meth) acrylate copolymer (A) was measured by the method described later, and the weight average molecular weight (Mw) was 600,000.

2. Preparation of adhesive composition

100 parts by mass of the (meth) acrylate copolymer (A) obtained in the above process (1) (converted solid content; the same applies hereinafter), trimethylolpropane-modified toluene as a crosslinking agent (B) Diisocyanate (manufactured by Soken Chemical & Engineering Co., Ltd., product name "L-45") 0.25 parts by mass, 3-glycidyl ether propyl trimethoxy decane as a decane coupling agent (Shin-Etsu Chemical Co., The product name "KBM-403", 0.2 parts by mass, was mixed and stirred, and diluted with methyl ethyl ketone to obtain a coating solution of an adhesive composition having a solid content concentration of 40% by mass.

Here, the adhesion of the adhesive composition is shown in Table 1. In addition, the detailed description of the abbreviations and the like described in Table 1 is as follows.

[(Meth)acrylate copolymer (A)]

BA: n-butyl acrylate

2EHA: 2-ethylhexyl acrylate

MMA: methyl methacrylate (hard monomer)

HEA: 2-hydroxyethyl acrylate

IBXA: isobornyl acrylate (hard monomer)

ACMO: propylene morpholine (hard monomer)

A-LEN: ethoxylated o-phenylphenol acrylate (Shin-Nakamura Chemical Industry Co., Ltd.)

BzA: benzyl acrylate

AA: Acrylic

V-3F: 2,2,2-trifluoroethyl acrylate

[Crosslinking agent (B)]

TDI: Trimethylolpropane modified toluene diisocyanate (manufactured by Soken Chemical & Engineering Co., Ltd., product name "L-45")

XDI: Trimethylolpropane modified xylylene diisocyanate (manufactured by Soken Chemical & Engineering Co., Ltd., product name "TD-75")

Epoxy: 1,3-bis(glycidyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Company Inc., product name "TETRAD-C")

3. Manufacture of adhesive sheets

The coating solution of the obtained adhesive composition was applied to the polyethylene terephthalate film with an anthrone-based release agent by a knife coater so that the thickness after drying became 25 μm. The peeling-treated surface of the heavy-peelable release sheet (product name "SP-PET752150" manufactured by Lintec Corporation) which was subjected to the release treatment was heat-treated at 100 ° C for 4 minutes to form a coating layer. Similarly, the coating solution of the obtained adhesive composition was applied to the polyethylene terephthalate using an anthrone-based release agent by a knife coater so that the thickness after drying became 25 μm. The peeling-treated surface of the light-peelable release sheet (manufactured by Lintec Corporation, product name "SP-PET382120") which was subjected to the release treatment on one side of the ester film was heat-treated at 100 ° C for 4 minutes to form a coating layer.

Next, the heavy peeling type of the coated layer obtained above is peeled off. The sheet and the light-peelable release sheet with the coating layer obtained above were bonded in such a manner that the two coating layers were in contact with each other, and cured at 23 ° C and 50% RH for 7 days, thereby producing An adhesive sheet composed of a structure of a heavy release type release sheet/adhesive layer (thickness: 50 μm)/light release type release sheet was used. In addition, the thickness of the adhesive layer is a value measured by a constant pressure thickness measuring instrument (product name "PG-02" by TECLOCK Company Inc.) based on JIS K7130.

[Examples 2 to 24, Comparative Examples 1 to 4]

The type, ratio, and polymerization average molecular weight (Mw) of each monomer constituting the (meth) acrylate copolymer (A), the type and amount of the crosslinking agent (B), and the blending of the decane coupling agent (C) An adhesive sheet was produced in the same manner as in Example 1 except that the amounts were changed as shown in Table 1. Further, in Examples 7 to 9, benzyl benzoate (manufactured by Tokyo Chemical Industry Co., Ltd.) as a refractive index adjusting agent was further blended in the adhesive composition. The amount of compounding is shown in Table 1.

Here, the weight average molecular weight (Mw) is a polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement).

<Measurement conditions>

‧GPC measuring device: manufactured by Tosoh Corporation, HLC-8020

‧GPC column (passed in the following order): manufactured by Tosoh Corporation

TSK guard column HXL-H

TSK gel GMHXL (×2)

TSK gel G2000HXL

‧ Determination of solvent: tetrahydrofuran

‧Measurement temperature: 40 ° C

[Test Example 1] (Measurement of adhesion)

The adhesive sheet obtained from the examples and the comparative examples was peeled off from the light release type release sheet, and the exposed adhesive layer was bonded to a polyethylene terephthalate film having an easy adhesion layer (manufactured by Toyobo Co., Ltd. , PETA4300, thickness: 100 μm) easy adhesion layer. The laminate was cut into a width of 25 mm and a length of 100 mm to prepare a sample.

On the other hand, a transparent conductive film (Oike Industry Co) in which a transparent conductive film (ITO film) made of tin-doped indium oxide (ITO) is formed on one side of a polyethylene terephthalate (PET) film (Oike Industry Co) , ITO film, thickness: 125 μm), fixed to the glass plate with the PET film side in contact with the glass plate.

The heavy release type release sheet was peeled off from the sample, and the exposed adhesive layer was bonded to the transparent conductive film. The above-mentioned sticking was carried out by pressurizing at a temperature of 50 ° C under a pressure of 0.5 MPa for 20 minutes.

Thereafter, it was allowed to stand under normal pressure, 23 ° C, and 50% RH for 24 hours, and then subjected to a tensile tester (Tensilon, manufactured by Orientec Company Inc.) to JIS Z0237:2009 at a peeling speed of 300 mm/min. The adhesion (N/25 mm) was measured under the conditions of a peeling angle of 180°. The results are shown in Table 2.

[Test Example 2] (Measurement of storage elastic modulus)

The release sheets were peeled off from the adhesive sheets obtained in the examples and the comparative examples, and a plurality of layers were laminated in such a manner that the adhesive layer became 3 mm thick. A cylindrical body (having a height of 3 mm) having a diameter of 8 mm was punched out from the laminated body of the obtained adhesive layer as a sample.

With respect to the above sample, the storage elastic modulus (MPa) was measured by a torsional shear method under the following conditions using a viscoelasticity measuring instrument (DYNAMIC ANALAYZER, manufactured by REOMETRIC Co., Ltd.) based on JIS K7244-6. The results are shown in Table 2.

Measurement frequency: 1 Hz

Measuring temperature: 80 ° C

[Test Example 3] (Measurement of refractive index)

Using an Abbe refractometer (Atago, Company Inc., product name "Abbe refractometer DR-M2", Na light source, wavelength: 589 nm), based on JIS K0062-1992, obtained in the examples and comparative examples. The refractive index of the adhesive layer of the adhesive sheet was measured. The results are shown in Table 2.

[Test Example 4] (Evaluation of pattern identification)

An ITO film of a transparent conductive film (ITO film made of Oike Industry Co., Ltd.) made of a transparent conductive film (ITO film) made of tin-doped indium oxide (ITO) is provided on one surface of a PET film having a thickness of 125 μm. On the top, a plurality of polyimine imide tapes (width 1 cm) were attached in parallel at intervals of 1 cm.

The obtained laminate was immersed in hydrochloric acid adjusted to 1 mol/l for 2 minutes, and the ITO film portion to which the above-mentioned polyimide adhesive tape was not adhered was etched. Next, the laminate was sufficiently washed with ion-exchanged water, and then dried at 120 ° C for 10 minutes, and then the polyimide film was peeled off from the transparent conductive film. Thus, a transparent conductive film in which an ITO film was patterned in such a manner that the ITO film portion having a width of 1 cm and the non-existing portion of the ITO film having a width of 1 cm were alternately alternated were obtained.

Next, the transparent conductive film in which the ITO film was patterned as described above was annealed at 150 ° C for 90 minutes to pattern The ITO film is crystallized.

On the other hand, the light release sheet was peeled off from the adhesive sheets obtained in the examples and the comparative examples, and the exposed adhesive was laminated on a PET film having a thickness of 100 μm. Then, the heavy release-type release sheet was peeled off from the adhesive layer laminated on the PET film (thickness: 100 μm), and the exposed adhesive layer was bonded to the patterned ITO film of the above-mentioned transparent conductive film (crystallization) ()). Thus, an evaluation sample composed of a PET film (thickness: 125 μm)/patterned ITO film/adhesive layer/PET film (thickness: 100 μm) was obtained.

From the side of the transparent conductive film of the obtained evaluation sample, that is, the PET film side having a thickness of 125 μm, the patterned ITO film was visually observed under a fluorescent lamp, and thus, the pattern identification of the adhesive layer was evaluated based on the following criteria. Sex (the apparentness of the pattern of the transparent conductive film). The results are shown in Table 2.

◎: The graphic is not visible.

○: The graphic is faintly visible.

×: The graphic is visible.

[Test Example 5] (segment difference follow-up evaluation)

(a) Production of samples for evaluation

The surface of a glass plate (manufactured by NSG Precision Company Inc., product name "Corning Glass Eagle XG", longitudinal length 90 mm × horizontal length 50 mm × thickness 0.5 mm) was applied in a thickness of 5 μm, 10 μm, 15 μm, and 20 μm. An ultraviolet curable ink (manufactured by Teikoku Ink Mfg. Co., Ltd., product name "POS-911 ink") was screen-printed in a frame shape (outer shape: vertical length 90 mm × horizontal length 50 mm, width 5 mm). Next, ultraviolet rays (80 W/cm ² , two metal halide lamps, a lamp height of 15 cm, and a belt speed of 10 to 15 m/min) were irradiated, and the above-mentioned ultraviolet curable ink was hardened by printing to produce a step difference based on printing (step height) : 5 μm, 10 μm, 15 μm, and 20 μm) with a stepped glass plate.

The light release sheet was peeled off from the adhesive sheets obtained in the examples and the comparative examples, and the exposed adhesive layer was attached to a polyethylene terephthalate film having an easy adhesion layer (Toyobo Co., Ltd. System, PET100A4300, thickness: 100μm) easy adhesion layer. Next, the heavy release type release sheet was peeled off to expose the adhesive layer. Further, the laminate was laminated on each of the stepped glass sheets by means of a laminator (manufactured by Fujipura Company Inc., product name "LPD3214") so that the entire printing surface of the frame was covered with the adhesive layer, by hot pressing A sample for evaluation was obtained by treatment (50 ° C, 0.5 MPa, 30 minutes).

(b) Evaluation of samples for evaluation

Regarding the sample for evaluation described above, first, the step difference followability of the sample segment for evaluation was evaluated as "initial". The step followability is judged by whether or not the printing step is completely filled by the adhesive layer. When a gap or a bubble is observed at the interface between the printing step and the adhesive layer, it is judged that the printing step cannot be followed. Here, the step followability is evaluated as the step follow rate (%) according to the following criteria.

Next, the sample for evaluation was placed in an environment of 85 ° C and 85% RH for 72 hours. Thereafter, the film was returned to a normal temperature and a normal humidity state of 23° C. and 50% RH, and the step followability of the sample for evaluation was evaluated as “after durability” in the same manner as described above. The results of each evaluation are shown in Table 2.

Segment following rate %={(printing step height without gaps and bubbles and being filled (μm)) / (thickness of adhesive layer: 50 μm)}×100

◎: step follow rate of 40%

○: Step follow rate of 10%~30%

×: The step follow rate is less than 10%

[Test Example 6] (Evaluation of moisture and heat resistance)

The adhesive layer of the adhesive sheet obtained in the examples and the comparative examples was sandwiched between two pieces of soda lime glass (thickness: 1.1 mm) to obtain a laminate. The haze value (%) was measured by a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH2000") based on JIS K7136:2000.

Next, the laminate was stored under the damp heat conditions of 85 ° C and 85% RH for 72 hours. After that, it was returned to normal temperature and humidity of 23 ° C and 50% RH, and a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH2000") was used as a reference for JIS K7136:2000. The haze value (%) was measured. Further, the haze value was measured within 30 minutes after returning the laminate to normal temperature and normal humidity.

Based on the above results, the haze value before the moist heat condition was subtracted from the haze value after the moist heat condition, and the haze value after the moist heat condition was calculated to increase (point). When the haze value after the wet heat condition was increased by less than 1.0, the wet heat whitening property was evaluated as good (?), and the haze value after the wet heat condition was increased by 1.0 or more and less than 5.0, and it was evaluated as the moisture heat whitening suitability value. (○), when the haze value after the wet heat condition was increased to 5.0 or more, it was evaluated as poor wet heat whitening property (×). The results are shown in Table 2.

[Test Example 7] (Evaluation of blister resistance)

The adhesive layer of the adhesive sheet obtained in the examples and the comparative examples was used for a transparent conductive film (Oike Industry Co., which was provided with a transparent conductive film made of tin-doped indium oxide (ITO) on one side of the PET film. Ltd., ITO thin A transparent conductive film of a film having a thickness of 125 μm and a polycarbonate plate (manufactured by Mitsubishi Gas Chemical Company, Jupilon Sheet MR58, thickness: 1 mm) were sandwiched to obtain a laminate.

The obtained laminate was subjected to hot press treatment at 50 ° C and 0.5 MPa for 30 minutes, and then left for 15 hours. Subsequently, it was stored under the endurance conditions of 85 ° C and 85% RH for 72 hours. Thereafter, it was confirmed by visual observation whether or not bubbles, floating or peeling were present in the adhesive layer. As a result, those who were completely free of air bubbles, floated, and peeled were evaluated as ◎, those who produced only bubbles having a diameter of 0.2 mm or less were evaluated as ○, and those whose diameters exceeded 0.2 mm were evaluated as × (resistant) Evaluation of foaming)). The results are shown in Table 2.

【Table 1】

【Table 2】

As can be seen from Table 2, according to the adhesive sheet obtained in the examples, the pattern of the transparent conductive film was not conspicuous, and excellent step followability and blister resistance were achieved. In particular, the adhesive sheets obtained in Examples 1 to 23 were also excellent in moist heat whitening resistance, and the adhesive sheets obtained in Examples 1 to 22 and 24 also had excellent adhesion.

[Industrial availability]

The adhesive and the adhesive sheet of the present invention are very useful for forming an adhesive layer used in a touch panel of an electrostatic capacitance type.

1‧‧‧Adhesive film

11‧‧‧Adhesive layer

12a, 12b‧‧‧ peeling film

Claims (8)

An adhesive for use in an electrostatic capacitance type touch panel between two transparent conductive films or between a transparent conductive film and a cover material, characterized by a refractive index of 1.45 to 1.54 and storage at 80 ° C The modulus of elasticity is 0.02 to 0.10 MPa, and does not contain a component having a carboxyl group. The adhesive according to claim 1, wherein the adhesive is crosslinked by an adhesive composition containing the (meth) acrylate copolymer (A) and the crosslinking agent (B). In the (meth) acrylate copolymer (A), the monomer unit constituting the polymer contains 5 to 30% by mass of a monomer having a hydroxyl group, and does not have a glass transition as a homopolymer. The hard monomer having an aromatic ring having a temperature of 70 ° C or more is 5 to 40% by mass, and does not contain a monomer having a carboxyl group. The adhesive according to claim 2, wherein the (meth) acrylate copolymer (A) has a weight average molecular weight of 200,000 to 1,000,000. The adhesive according to claim 2, wherein in the (meth) acrylate copolymer (A), the monomer unit constituting the polymer, that is, the hard monomer, is selected from the group consisting of At least one of the group consisting of methyl acrylate, isobornyl acrylate, and acrylomorpholine. The adhesive according to claim 2, wherein the adhesive further contains a decane coupling agent (C). An adhesive sheet for use in a subsequent one of two transparent conductive films in a capacitive touch panel or a transparent conductive film and a cover material, The invention comprises: two release sheets; and an adhesive layer sandwiched by the release sheet in contact with the peeling surface of the two release sheets, wherein the adhesive layer is in the first to fifth aspects of the patent application. Any of the adhesive compositions described. The adhesive sheet according to claim 6, wherein the adhesive layer has a thickness of 10 to 400 μm. The adhesive sheet according to claim 6, wherein the adhesive layer is laminated on the adhesive layer side of the laminate on the substrate made of a polyethylene terephthalate film having a thickness of 100 μm. In the case where the surface is adhered to the soda lime glass, the adhesion of the laminate to the soda lime glass is 5 to 50 N/25 mm.