KR20130033437A - Adhesive for crystalline metal oxide conducting film and adhesive sheet for crystalline metal oxide conducting film using the same - Google Patents

Abstract

(A) 50-99 mass% of acrylic acid alkyl ester units whose C1-C20 alkyl group of (a-1) ester site | part, and (A-2) acrylic acid alkyl ester type copolymer containing 0.5-10 mass% of acrylic acid units The adhesive for crystalline metal oxide conductive film containing 0.01-2 mass parts of (B) metal chelate type crosslinking agents with respect to 100 mass parts of solid substances of the above. It is used to fix crystalline metal oxide conductive films such as tin-doped indium oxide (ITO) films and display devices such as LCDs, to suppress deterioration of conductive films such as ITO films as adherends, and to suppress an increase in electric resistance values. And a pressure-sensitive adhesive for a crystalline metal oxide conductive film, which is particularly suitable for a capacitive touch panel.

Description

Adhesive for crystalline metal oxide conductive film and adhesive sheet for crystalline metal oxide conductive film using the same {ADHESIVE FOR CRYSTALLINE METAL OXIDE CONDUCTING FILM AND ADHESIVE SHEET FOR CRYSTALLINE METAL OXIDE CONDUCTING FILM USING THE SAME}

The present invention relates to an adhesive for a crystalline metal oxide conductive film and an adhesive sheet for a crystalline metal oxide conductive film using the same. More specifically, the present invention provides a pressure-sensitive adhesive and an adhesive sheet used to fix a crystalline metal oxide conductive film such as a tin-doped indium oxide (ITO) film to a display device such as a liquid crystal display (LCD), which directly touches the adhesive face. It is possible to suppress deterioration of conductive films such as ITO films and to suppress an increase in electric resistance values, and is particularly preferable for crystalline metal oxide conductive films for capacitive touch panels, and adhesion for crystalline metal oxide conductive films using the same. It is about a sheet.

1 is a cross-sectional view showing an embodiment of a capacitive touch panel.

As shown in FIG. 1, the capacitive touch panel 16 has a surface material layer 1 such as a hard coat, a glass layer 2, a cosmetic printing layer 3, and an adhesive layer 4 for embedding on the surface side. , Glass layer 5, transparent conductive film 6, pressure-sensitive adhesive layer 7 for conductive film, and display device 8.

In the capacitive touch panel having such a configuration, when a weak voltage is applied to the transparent conductive film 6, electric charges are accumulated on the surface of the transparent conductive film 6 to form an electric field. When the surface material layer 1 is brought into contact with a conductor such as a finger or a touch pen, the electric field is changed and discharged. A weak current change flowing through four corners of the transparent conductive film 6 is calculated and detected to detect the contact position. Therefore, the adhesive which comprises the adhesive layer 7 for conductive films which fixes the transparent conductive film 6 and the display apparatus 8 requires the performance which does not change the capacitance (capacitance) of the transparent conductive film 6. . However, the conventional pressure-sensitive adhesive deteriorates the transparent conductive film in an environment of high temperature and high humidity, and increases the electrical resistance value. Therefore, it is not appropriate to use a capacitive touch panel.

On the other hand, about the adhesive composition for optical members used for transparent electrodes, such as a touch panel, since the acid component contained in an adhesive generally causes metal corrosion, a double-sided tape which does not use acidic groups, such as a carboxyl group, for an adhesive Was proposed (for example, refer patent document 1). Moreover, the (meth) acrylic-type polymer which contains 0.2-20 mass parts of carboxyl group-containing monomers as a copolymerization component with respect to 100 mass parts of alkyl (meth) acrylates which have a C4-C14 alkyl group as a monomer unit, and this (meth) The adhesive composition for optical members (for example, refer patent document 2) characterized by containing 0.02-2 mass parts of peroxides and 0.005-5 mass parts of epoxy type crosslinking agents as a crosslinking agent with respect to 100 mass parts of acrylic polymers. It is.

Patent Document 1: Japanese Patent Application Laid-Open No. 2005-325250 Patent Document 2: Japanese Patent Application Laid-Open No. 2009-242786

When the pressure-sensitive adhesive composition described in Patent Document 1 is adhered to an amorphous metal oxide conductive film, there is a problem that the resistance value is remarkably changed under an environment of high temperature and high humidity, and the punching processing ability is lowered due to the lack of cohesive force. .

Moreover, in the adhesive composition of the said patent document 2, although the carboxyl group-containing monomer is used as a monomer used as a crosslinking point, the metal chelate type crosslinking agent was not used as a crosslinking agent as a combination system of a peroxide and an epoxy type crosslinking agent.

Moreover, the objective of patent document 2 is the adhesive composition for optical members which can form the adhesive layer which can suppress the yellow change in high temperature, high temperature, high humidity environment, and can suppress foaming, peeling, etc. under high temperature, high temperature, high humidity environment. Since it is providing, it is not a technique which suppresses deterioration of a metal oxide conductive film.

The present invention has been made under such circumstances, and is an adhesive and an adhesive sheet used for fixing a crystalline metal oxide conductive film such as a tin-doped indium oxide (ITO) film and a display device such as an LCD. It is possible to suppress the deterioration of the conductive film, to suppress the increase in the electrical resistance value, and to provide a pressure-sensitive adhesive for the crystalline metal oxide conductive film, which is particularly suitable for a capacitive touch panel, and a pressure-sensitive adhesive sheet for the crystalline metal oxide conductive film using the same. For the purpose of

The inventors of the present invention, as a result of repeated studies to achieve the above object, an acrylic acid alkyl ester copolymer comprising acrylic alkyl ester units and acrylic acid units each having a predetermined number of carbon atoms of the alkyl group of the ester moiety in a specific ratio, and a metal It was found that the object can be attained by a pressure-sensitive adhesive containing a chelating crosslinking agent in a predetermined ratio, and particularly having a storage modulus at 65 ° C of 0.10 MPa or more. Based on this, the present invention has been completed.

That is,

[1] Acrylic acid alkyl ester containing 50 to 99 mass% of acrylic acid alkyl ester units having 1 to 20 carbon atoms and (a-2) acrylic acid unit, in which the alkyl group of the (A) (a-1) ester moiety is The adhesive for crystalline metal oxide conductive film containing 0.01-2 mass parts of (B) metal chelate type crosslinking agents with respect to 100 mass parts of solid materials of a system copolymer,

[2] The pressure sensitive adhesive for crystalline metal oxide conductive film according to the above [1], wherein the (a-1) acrylic acid alkyl ester unit is at least a butyl acrylate unit;

[3] The pressure-sensitive adhesive for crystalline metal oxide conductive film according to the above [1] or [2], wherein the storage modulus at 65 ° C. is 0.10 MPa or more.

[4] an adhesive sheet for a crystalline metal oxide conductive film, comprising a layer made of the pressure sensitive adhesive according to any one of [1] to [3].

[5] An adhesive sheet for a crystalline metal oxide conductive film, wherein only the layer made of the adhesive according to any one of [1] to [3] is sandwiched between two release sheets.

[6] The pressure-sensitive adhesive sheet for crystalline metal oxide conductive film according to the above [4] or [5], wherein the crystalline metal oxide conductive film to be adhered is crystalline tin-doped indium oxide.

[7] Adhesive sheet for crystalline metal oxide conductive film according to any one of [4] to [6], used as a member for a touch panel,

[8] A touch panel member comprising at least a layer made of the pressure-sensitive adhesive for crystalline metal oxide conductive film according to any one of [1] to [3] and a crystalline metal oxide conductive film;

[9] A touch panel member, which is laminated in order of a glass plate, a layer made of the pressure-sensitive adhesive for crystalline metal oxide conductive film according to any one of [1] to [3], and a crystalline metal oxide conductive film. , And

[10] The touch panel member according to the above [8] or [9], wherein the touch panel is a capacitive method.

According to the present invention, a pressure-sensitive adhesive and an adhesive sheet used for fixing a crystalline metal oxide conductive film such as a tin-doped indium oxide (ITO) film and a display device such as an LCD, are used to prevent deterioration of a conductive film such as an ITO film, which is an adherend. It is possible to suppress the increase in the electrical resistance value, and to provide a pressure-sensitive adhesive for crystalline metal oxide conductive film and a pressure-sensitive adhesive sheet for crystalline metal oxide conductive film, which are particularly suitable for capacitive touch panels.

1 is a cross-sectional view showing the configuration of an embodiment of a capacitive touch panel.
2 is a process explanatory diagram for sample preparation for resistance measurement.
3 is an explanatory diagram showing a method of measuring a resistance value between two points.
In the drawings, reference numeral 1 is a surface material layer, 2 is a glass layer, 3 is a cosmetic printing layer, 4 is a pressure-sensitive adhesive layer for embedding, 5 is a substrate for a conductive film, 6 is a transparent conductive film, 7 is a pressure-sensitive adhesive layer for a conductive film, 8 is a display device , 9 and 9 'are peeling sheets, 10 is slide glass, 11 is silver paste (electrode), 12 is ITO film, 13 is polyethylene terephthalate film, 14 is bonding tape, 15 is glass plate, 16 is capacitance Type of touch panel.

First, the pressure-sensitive adhesive for crystalline metal oxide conductive film of the present invention (hereinafter, abbreviated as "pressure-sensitive adhesive for conductive film") will be described.

The adhesive for conductive films of this invention is an adhesive for crystalline metal oxide conductive films, (A) 50-99 mass% of acrylic acid alkyl ester units whose alkyl group of a (a-1) ester site is C1-C20, (a-2) It is characterized by containing 0.01-2 mass parts of (B) metal chelate type crosslinking agents with respect to 100 mass parts of solid substances of the acrylic acid alkyl ester copolymer containing 0.5-10 mass% of acrylic acid units.

The pressure-sensitive adhesive for the conductive film of the present invention having such a composition can not only securely fix the crystalline metal oxide conductive film and the display device, but also suppress the deterioration of the crystalline metal oxide conductive film and increase the electrical resistance value. In particular, it exhibits a desirable effect for a capacitive touch panel.

[(A) acrylic acid alkyl ester copolymer]

In the pressure-sensitive adhesive for conductive film of the present invention, the acrylic acid alkyl ester copolymer used as the component (A) includes 50 to 99 mass% of an acrylic acid alkyl ester unit having 1 to 20 carbon atoms as the alkyl group of the (a-1) ester site, ( a-2) It is a copolymer containing 0.5-10 mass% of acrylic acid units.

((a-1) acrylic acid alkyl ester unit)

The acrylic acid alkyl ester unit of the unit (a-1) constituting the acrylic acid alkyl ester copolymer is a unit derived from an acrylic acid alkyl ester having 1 to 20 carbon atoms in its alkyl group.

Here, examples of the acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, pentyl acrylate, hexyl acrylate, cyclohexyl acrylate, and 2-ethyl. Hexyl acrylate, isooctyl acrylate, decyl acrylate, dodecyl acrylate, myristyl acrylate, palmityl acrylate, stearyl acrylate and the like. These may be used alone or two or more kinds thereof may be used in combination, but among them, butyl acrylate is preferred from the viewpoint of adhesion development.

The content of the (a-1) acrylic acid alkyl ester unit in the acrylic acid alkyl ester copolymer is required from 50 to 99% by mass from the viewpoint of the effect of the present invention, preferably from 60 to 98.5% by mass, more preferably from 70 to 98 mass%.

((a-2) acrylic acid unit)

The acrylic acid unit of the (a-2) unit constituting the acrylic acid alkyl ester copolymer is derived from acrylic acid used as the monomer, and the content of the acrylic acid unit in the acrylic acid alkyl ester copolymer is from the viewpoint of the effect of the present invention. It is 0.5-10 mass%, Preferably it is 1-6 mass%, More preferably, it is 2-4 mass%.

(Other monomer unit)

In the said acrylic acid alkyl ester type copolymer, in addition to the said (a-1) unit and (a-2) unit, other monomeric units other than the said (a-1) unit can be contained in a suitable quantity as needed in the range which does not impair the effect of this invention.

Examples of other monomer units include units derived from methacrylic acid alkyl esters corresponding to the acrylic acid alkyl esters exemplified above, acrylamide, methacrylamide, N-methyl acrylamide, N-methyl methacrylamide, N-methylol acryl Acrylamides such as amide and N-methylol methacrylamide; (Meth) acrylic acid monoalkyl aminoalkyl, such as monomethyl aminoethyl (meth) acrylate, monoethyl aminoethyl (meth) acrylate, monomethyl aminopropyl (meth) acrylate, and monoethyl aminopropyl (meth) acrylate; And units derived from ethylenically unsaturated carboxylic acids such as methacrylic acid, crotonic acid, maleic acid, itaconic acid and citraconic acid.

Furthermore, vinyl esters, such as vinyl acetate and a vinyl propionate; Olefins such as ethylene, propylene and isobutylene; Halogenated olefins such as vinyl chloride and vinylidene chloride; Styrene monomers such as styrene and α-methyl styrene; Diene monomers such as butadiene, isoprene and chloroprene; Nitrile monomers such as acrylonitrile and methacrylonitrile; And units derived from N, N-dialkyl substituted acrylamides such as N, N-dimethyl acrylamide and N, N-dimethyl methacrylamide.

These other monomer units introduced as needed may introduce | transduce 1 type and may introduce 2 or more types.

The acrylic acid alkyl ester copolymer preferably has a weight average molecular weight of 600,000 or more. When this weight average molecular weight is less than 600,000, the adhesive durability under high temperature, high humidity is not enough, and it may float or peel. In consideration of adhesive durability, the weight average molecular weight is more preferably 650,000 to 2.2 million, particularly preferably 700,000 to 2 million.

In addition, the said weight average molecular weight is the polystyrene conversion value measured by the gel permeation chromatography (GPC) method.

[(B) Metal Chelate Crosslinking Agent]

In the pressure-sensitive adhesive for conductive films of the present invention, a metal chelate-based crosslinking agent is used as the component (B) from the viewpoint of increasing the elastic modulus of the pressure-sensitive adhesive.

Specific examples of this metal chelate-based crosslinking agent include tri-n-butoxy ethyl acetoacetate zirconium, di-n-butoxy bis (ethyl acetoacetate) zirconium, n-butoxy tris (ethyl acetoacetate) zirconium, tetrakis ( zirconium chelate-based crosslinking agents such as n-propyl acetoacetate) zirconium, tetrakis (acetyl acetoacetate) zirconium, and tetrakis (ethyl acetoacetate) zirconium; Titanium chelate crosslinking agents such as diisopropoxy bis (ethyl acetoacetate) titanium, diisopropoxy bis (acetyl acetate) titanium, diisopropoxy bis (acetyl acetone) titanium; Diisopropoxy ethyl acetoacetate aluminum, diisopropoxy acetyl acetonate aluminum, isopropoxy bis (ethyl acetoacetate) aluminum, isopropoxy bis (acetyl acetonate) aluminum, tris (ethyl acetoacetate) aluminum, tris ( Aluminum chelate crosslinking agents, such as acetyl acetonate) aluminum and monoacetyl acetonate bis (ethyl acetoacetate) aluminum, etc. are mentioned.

Among these metal chelate crosslinking agents, an aluminum chelate crosslinking agent is preferable from the viewpoint of the effect of increasing the elastic modulus of the pressure-sensitive adhesive and economical efficiency. These metal chelate crosslinking agents may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, it can use together with another crosslinking agent in the range which does not impair the effect of this invention.

The content of the metal chelate-based crosslinking agent as the component (B) in the pressure-sensitive adhesive for conductive film of the present invention is to increase the elastic modulus of the pressure-sensitive adhesive and also to express the adhesive force. 0.01-2 mass parts is needed with respect to a mass part, Preferably it is 0.05-1.6 mass parts, More preferably, it is 0.1-1.2 mass parts.

[Optional component]

The pressure-sensitive adhesive for conductive films of the present invention may contain a silane coupling agent for the purpose of improving adhesion and durability. It may also contain other known additives, for example, powders such as colorants, pigments, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, antioxidants, light stabilizers, A ultraviolet absorber, a polymerization inhibitor, etc. can also be contained.

(Silane coupling agent)

Specific examples of the silane coupling agent include polymerizable unsaturated group-containing silicon compounds such as vinyl trimethoxysilane, vinyl triethoxysilane and methacryloxypropyl trimethoxysilane, 3-glycidoxypropyl trimethoxysilane, and 2- Silicon compounds having an epoxy structure such as (3,4-epoxycyclohexyl) ethyl trimethoxysilane, 3-aminopropyl trimethoxysilane, N- (2-aminoethyl) -3-aminopropyl trimethoxysilane, And amino group-containing silicon compounds such as N- (2-aminoethyl) -3-aminopropyl methyldimethoxysilane, 3-chloropropyl trimethoxysilane, and the like. These may be used singly or in combination of two or more.

The content of this silane coupling agent is preferably in the range of 0.001 to 10 parts by mass, and more preferably in the range of 0.005 to 5 parts by mass with respect to 100 parts by mass of the acrylic acid alkyl ester copolymer of the component (A) described above.

It is preferable that the adhesive for conductive films of this invention is 0.10 Mpa or more of storage elastic modulus of an adhesive at 65 degreeC, and when storage elastic modulus is less than 0.10 MPa, it is difficult to support the interface of an adherend and an adhesive in an environment of high temperature, high humidity, and a metal oxide conductive film This is undesirable because cracks on the surface increase the electrical resistance value. In addition, in this application, the storage elastic modulus of an adhesive at 65 degreeC shall be measured in accordance with the method as described in (2) of an Example.

The pressure-sensitive adhesive of the present invention is for a crystalline metal oxide conductive film, and is preferable as the crystalline metal oxide because it has a high effect on suppression of an increase in the electrical resistance value with respect to a metal oxide having high crystallinity. (ITO), zinc oxide, tin oxide, titanium oxide, IZO, GZO, ATO, etc. are mentioned.

Although it does not restrict | limit otherwise as a formation method of a conductive film, The formation method by the sputtering method is preferable from a viewpoint of transparency or the performance of an electrical resistance value. As the conductive film, one in which a metal oxide having a film thickness of 1 µm or less is sputtered onto a substrate for a conductive film such as a plastic film or a glass plate.

When the substrate for the conductive film is a glass plate, glass may include soda glass, lead oxide glass, borosilicate glass, quartz glass, and the like. Examples of the main component of the glass include silicon dioxide and aluminum oxide, sodium oxide, magnesium oxide, calcium oxide, boron oxide, phosphorus oxide, iron oxide, potassium oxide, titanium oxide, zinc oxide and the like.

When the substrate for the conductive film is a plastic film, the plastic film may be a transparent film, for example, a polyester resin such as polyethylene telephthalate or polyethylene naphthalate, an acetate resin, a polyether sulfone resin, a polycarbonate resin, or poly Amide resin, polyimide resin, polyolefin resin, polycycloolefin resin, (meth) acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl alcohol resin, polyarylene Resin, polyphenylene sulfide resin, and the like. Among these, particularly preferred examples thereof include polyester resins, polyimide resins, and polyether sulfone resins.

 Next, the adhesive sheet for a crystalline metal oxide conductive film of the present invention (hereinafter abbreviated as "adhesive sheet for conductive film") will be described.

In the pressure-sensitive adhesive sheet for a conductive film of the present invention, the pressure-sensitive adhesive sheet I for a crystalline metal oxide conductive film having the above-described layer of the pressure-sensitive adhesive for a conductive film on one side of the base sheet, the layer of the pressure-sensitive adhesive for the conductive film of the present invention There are three forms of the adhesive sheet II for the crystalline metal oxide conductive film which has both surfaces, and the adhesive sheet III for the crystalline metal oxide conductive film which inserted only the layer which consists of the adhesive agent for conductive films of this invention mentioned above between two peeling sheets.

[Adhesive Sheets I and II for Conductive Films]

The adhesive sheet I for conductive films of this invention has a layer which consists of the adhesive agent for conductive films of this invention mentioned above on one side of a base material sheet. Moreover, the adhesive sheet II for a crystalline metal oxide conductive film is characterized by having the layer which consists of the adhesive for conductive films of this invention mentioned above on both surfaces of a base material sheet.

In the adhesive sheets I and II for conductive films of this invention, the thickness of the layer which consists of adhesives for conductive films is 5-500 micrometers normally, Preferably it is 10-300 micrometers, Especially preferably, it is 20-200 micrometers.

(Base sheet)

The substrate sheet is not particularly limited as long as it has transparency, and examples thereof include polyester films such as polyethylene telephthalate, polybutylene telephthalate and polyethylene naphthalate, polyethylene films, polypropylene films, polyvinyl chloride films, and polyvinylidene. Chloride film, polyvinyl alcohol film, ethylene vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyether ether ketone film, polyether sulfone film, polyphenylene sulfide film, polyether Plastic films, such as a mid film, a polyimide film, a fluororesin film, a polyamide film, an acrylic resin film, a norbornene-type resin film, and a cycloolefin resin film, are mentioned.

The thickness of the said plastic film is about 10-300 micrometers normally, Preferably it is 20-200 micrometers.

In addition, the plastic film can be subjected to surface treatment or primer treatment on one or both surfaces by an oxidation method, concavities and convexities, etc., as desired, for the purpose of improving adhesion with the pressure-sensitive adhesive layer formed on the surface thereof. Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromic acid treatment (wet), flame treatment, hot air treatment, ozone ultraviolet irradiation treatment, and the like. Method, solvent treatment method, and the like. Although these surface treatment methods can be suitably selected according to the kind of plastic film, in general, a corona discharge treatment method is used preferably from a viewpoint of an effect, operability, etc.

(Peeling sheet)

The release sheet is formed by applying a release agent such as silicone resin to a plastic film such as a polyester film such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, or a polyolefin film such as polypropylene or polyethylene. Etc. can be mentioned. Although it does not restrict | limit otherwise about the thickness of this peeling sheet, Usually, it is about 20-150 micrometers.

(Production of Adhesive Sheets I and II for Conductive Films)

In preparation of the adhesive sheet I for electrically conductive films, the coating liquid for adhesive layer formation is prepared first. There is no restriction | limiting in particular in the preparation method of this coating liquid, For example, (A) component, (B) component which were mentioned above in a solution, and other arbitrary components are added as needed, and the mixing solution for adhesive layer formation is added by stirring and mixing. To prepare.

Examples of the solvent include aliphatic hydrocarbons such as hexane and heptane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone. Esters such as ketones, ethyl acetate and butyl acetate, cellosolve solvents such as ethyl cellosolve, glycol ether solvents such as propylene glycol monomethyl ether, and the like. These solvent may be used individually by 1 type, and may mix and use 2 or more types.

The concentration of the solid substance in this coating liquid is not otherwise limited as long as the coating liquid is a viscosity suitable for coating.

Next, on the release layer of the release sheet, the coating liquid for pressure-sensitive adhesive layer formation is, 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. It is apply | coated using and dried, and an adhesive layer is formed. Next, the adhesive sheet I for conductive films of this invention is obtained by sticking the adhesive layer with this peeling sheet to one side of the base material sheet mentioned above through this adhesive layer.

Moreover, after apply | coating the coating liquid for adhesive layer formation adjusted as mentioned above on the peeling layer of another peeling sheet similarly, and drying to form an adhesive layer, this adhesive layer is the base material sheet of the adhesive sheet I for conductive films mentioned above. By bonding to a surface, the adhesive sheet II for conductive films of this invention is obtained.

On the other hand, in the case where the pressure-sensitive adhesive layer with the release sheet is adhered to both sides of the base sheet, a pressure-sensitive adhesive layer with a heavy peeling type release sheet (also referred to as a heavy peeling sheet) is attached to one side, and a light ( (Iii) A pressure-sensitive adhesive layer with a peelable release sheet (also referred to as a light peeling sheet) can be attached.

[Adhesive Sheet III for Conductive Film]

The adhesive sheet III for conductive films of this invention is characterized by sandwiching only the layer which consists of the adhesive agent for conductive films of this invention mentioned above between two peeling sheets. The adhesive sheet III for conductive films does not have a base sheet like the adhesive sheets I and II for conductive films described above.

(Production of Adhesive Sheet III for Conductive Films)

The adhesive sheet III for conductive films of this invention can be produced, for example by the method described below.

First, on the peeling layer of a heavy peeling type peeling sheet, the coating liquid for adhesive layer formation is apply | coated and dried similarly to manufacture of the adhesive sheet I for conductive films mentioned above, and an adhesive layer is formed. Subsequently, the adhesive sheet III for conductive films of the present invention can be obtained by adhering the light-peelable release sheet to the adhesive layer surface such that the release layer is in contact with the adhesive layer.

The adhesive sheets I, II, and III for the conductive film of the present invention are preferably crystalline tin-doped indium oxide (ITO) for the crystalline metal oxide conductive film to be adhered, and also for touch panels, in particular, capacitive touch panel members. It is preferably used as.

The touch panel member of the present invention has a structure in which the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for a conductive film mentioned above is bonded to face the surface of the crystalline metal oxide conductive film formed on the substrate for a conductive film described above. The member for a touch panel of the present invention is also an adherend through the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for the conductive film on the side opposite to the surface of the pressure-sensitive adhesive sheet for the conductive film that is in contact with the crystalline metal oxide conductive film or through another pressure-sensitive adhesive layer. (Hereinafter, also referred to as an adherend on the opposite side of the metal oxide conductive film in the present invention). Examples of the adherend on the opposite side of the metal oxide conductive film include a glass plate, a transparent plastic plate such as polycarbonate and a (meth) acrylic resin, and the like, but a glass plate is preferable from the viewpoint of suppressing the resistance increase rate. These adherends can be used as a protection panel of the outermost surface part of a touch panel, for example among members for touch panels.

Example

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

On the other hand, the electric resistance value measuring method of ITO and the measuring method of storage elastic modulus are performed according to the method described below.

(1) How to measure the electrical resistance of ITO

With reference to FIG. 2, the sample for resistance value measurement used for an electrical resistance value measurement test is demonstrated. By sputtering, the polyethylene telephthalate film 13 having the ITO film 12 formed on the surface is prepared, and the glass plate 15 is bonded to the side where the ITO film 12 of the polyethylene telephthalate film 13 is not formed. It bonded by the tape 14 (LINTEC Corporation make, product name 'tack liner TL-70'). Subsequently, a conductive resin material (manufactured by FUJIKURAKASEI CO.LTD., Product name 'FA-301CA' DOTITE touch panel circuit type) containing silver on the surface of the ITO film 12 was used. It apply | coated and heated and dried at 80 degreeC for 20 minutes, and produced two electrodes 11 which become a measuring point of a resistance value. At this time, the position was adjusted so that the distance between two points might be 26 mm.

The conductive sheet adhesive sheet III (FIG. 2 (A)) obtained in Examples and Comparative Examples was cut to a size of 26 mm x 250 mm, and the peeling sheet 9 'was peeled off from the adhesive sheet III for conductive films to form an electrode on the ITO sputtering surface. Adhesion was carried out along two points of (11) (not to be in close contact). Subsequently, the other peeling sheet 9 of the adhesive sheet III for conductive films III of FIG. 2 (B) was peeled off, and slide glass 10 [Matsunami Glass Co., Ltd.] of 1.0 mm in thickness and 26 mm in width | variety as an opposite adherend of a metal oxide conductive film. The sample for resistance measurement of FIG. 2 (C) was made by joining "MICRO SLIDE GLASS" made by Matsunami Glass Ind., Ltd ..

Next, to measure the digital tester high initial resistance R ₀ between [manufactured by Hioki Denki right or wrong (HIOKI EE CORPORATION) first, "3802-50"] using the electrode 11 as shown in Fig. After leaving the sample for resistance measurement for 500 hours in an environment of a temperature of 65 ° C. and a humidity of 95%, the resistance value R was measured after acceleration of moist heat. The resistance increase rate was calculated as follows. If this resistance value increase rate is less than 20%, it is a pass.

% Increase in resistance value = {(RR ₀ ) / R ₀ } x 100

(2) Measurement method of storage modulus

The peeling sheet of the adhesive sheet III for electrically conductive films obtained by the Example and the comparative example was removed, and several sheets were piled up and the sheet sample of thickness 2.0mm was formed. The formed sheet sample was measured for storage elastic modulus at 65 ° C. at a measurement frequency of 1 Hz using a viscoelasticity measuring device (trade name 'RDAII' manufactured by Rheometry Scientific Co., Ltd.).

Example 1

Isocyanate-based crosslinking agent [to 100 parts by mass of toluene solution of acrylic ester copolymer (butyl acrylate: methyl acrylate: acrylic acid (mass part) = 77: 20: 3, weight average molecular weight Mw = 800,000, concentration 28 mass%) TOKYO INK CO.LTD., [BHS-8515] concentration 37.5 mass%] 1.75 mass parts and aluminum chelate crosslinking agent [Soken Chemical Engineering Co., Ltd. ), 'M-5A' concentration 4.95 mass%] A heavy peeling sheet [made by Lintec Co., Ltd. product name] SP-PET38 T103-1 so that the film thickness after drying the acrylic adhesive solution prepared by mixing 1.75 mass parts was prepared to be 25 micrometers. After apply | coating to "] and heating at 120 degreeC for 2 minutes, the light peeling sheet (The product made by Lintec, product name" SP-PET38 1031 '") was bonded to the adhesive surface, and the adhesive sheet III for conductive films was obtained.

At this time, the addition amount of the aluminum chelate crosslinking agent with respect to 100 mass parts of solid materials of the acrylic ester copolymer was 0.31 mass part.

Example 2

Aluminum chelate crosslinking agent in 100 mass parts of toluene solution of acrylic ester copolymer (butyl acrylate: ethyl acrylate: acrylic acid (mass part) = 77: 20: 3, weight average molecular weight Mw = 900,000, concentration 30 mass%) [Made by Soken Kagaku Co., Ltd., 4.95 mass% in concentration of 'M-5A'] A pressure-sensitive adhesive sheet III for a conductive film was obtained in the same manner as in Example 1 except that an acrylic pressure-sensitive adhesive solution prepared by mixing 4 parts by mass was used.

At this time, the addition amount of the aluminum chelate crosslinking agent with respect to 100 mass parts of solid substances of the acrylic ester copolymer was 0.66 mass part.

Comparative Example 1

100 parts by mass of toluene solution of acrylic ester copolymer (butyl acrylate: methyl acrylate: 4-hydroxybutyl acrylate (mass part) = 79: 20: 1, weight average molecular weight Mw = 900,000, concentration 30 mass%) 0.05 part by mass of an isocyanate-based crosslinking agent [manufactured by Soken Kagaku KK, 'TD-75' concentration 75% by mass] and a silane coupling agent [Shin-Etsu Chemical Co., Ltd.) First, 'KBM403' concentration 100%] A pressure-sensitive adhesive sheet III for conductive films was obtained in the same manner as in Example 1 except that an acrylic pressure-sensitive adhesive solution prepared by mixing 0.15 parts by mass was used.

Comparative Example 2

Acrylic ester copolymer (butyl acrylate: methyl acrylate: 2-hydroxyethyl acrylate: acryloyl morpholine (mass part) = 79: 2: 2: 2: 17, weight average molecular weight Mw = 900,000, concentration 35.1 mass Example 1 except that the acrylic pressure-sensitive adhesive solution prepared by mixing 0.5 parts by mass of an isocyanate-based crosslinking agent (37.5 mass% of 'BHS-8515' concentration of 'BHS-8515' manufactured by Toyo Ink Co., Ltd.) with 100 parts by mass of the toluene solution of%) was used. In the same manner, PSA sheet III for a conductive film was obtained.

Comparative Example 3

Isocyanate to 100 parts by mass of toluene solution of acrylic ester copolymer (2-ethylhexyl acrylate: cyclohexyl acrylate: acrylic acid (mass part) = 59.7: 40: 0.3, weight average molecular weight Mw = 800,000, concentration 40 mass%) A pressure-sensitive adhesive sheet III for conductive films was obtained in the same manner as in Example 1, except that an acrylic pressure-sensitive adhesive solution prepared by mixing 0.5 parts by weight of a cross-linking agent [Toyo Inky Co., Ltd., 'BHS-8515' concentration 37.5 mass%] was prepared. .

Comparative Example 4

Isocyanate type crosslinking agent to 100 mass parts of toluene solution of acrylic ester copolymer (butyl acrylate: isobutyl acrylate: acrylic acid (mass part) = 49.125: 49.125: 1.75, weight average molecular weight Mw = 500,000, concentration 32 mass%) [A Toyo Ink Co., Ltd. make, BHS-8515 'concentration 37.5 mass%] The adhesive sheet III for conductive films was obtained by the same method as Example 1 except having used the acrylic adhesive solution prepared by mixing 3 mass parts.

Comparative Example 5

Acrylic acid ester copolymer (butyl acrylate: methyl acrylate: 2-hydroxyethyl acrylate: acryloyl morpholine (mass part) = 83.5: 2: 0.5: 14, weight average molecular weight Mw = 700,000, concentration 35.1 mass Example 1 except that the acrylic pressure-sensitive adhesive solution prepared by mixing 1.8 parts by weight of an isocyanate-based crosslinking agent (37.5 mass% of 'BHS-8515' concentration, manufactured by Toyo Inky Co., Ltd., with a concentration of 37.5 mass% of 'BHS-8515') was used. In the same manner, PSA sheet III for a conductive film was obtained.

Comparative Example 6

Isocyanate crosslinking agent [Toyo Inky Co., Ltd. product] to 100 mass parts of toluene solutions of acrylic ester copolymer (butyl acrylate: acrylic acid (mass part) = 91: 9, weight average molecular weight Mw = 600,000, concentration 30 mass%)) , 'BHS-8515' concentration 37.5 mass%] A pressure-sensitive adhesive sheet III for conductive films was obtained in the same manner as in Example 1, except that an acrylic pressure-sensitive adhesive solution prepared by mixing 2 parts by mass was used.

Comparative Example 7

The toluene solution of the acrylic ester copolymer (butyl acrylate: acrylic acid (mass part) = 90: 10, weight average molecular weight Mw = 400,000, concentration 35 mass%) was used as the acrylic adhesive solution, and the crosslinking agent was not used. Except for the conductive film adhesive sheet III in the same manner as in Example 1.

Initial resistance value R using the adhesive sheet III for electrically conductive films obtained by Examples 1 and 2 and Comparative Examples 1-7, according to the measuring method of the electrical resistance of ITO of above (1), and the storage elastic modulus of (2). The resistance value R after ₀ and 500 hours was measured, the resistance value increase rate was calculated | required, and the storage elastic modulus at 65 degreeC was also measured.

These results are shown in Table 1.

In addition, when measuring the electrical resistance value of ITO of said (1) using the adhesive sheet III for electrically conductive films obtained in Example 1, the result measured using amorphous ITO instead of crystalline ITO was compared as a comparative example 1. Table 1 shows. Similarly, Example 2 is also shown in Table 1 as Control Example 2.

In addition, when measuring the electrical resistance value of ITO of said (1) using the adhesive sheet III for electrically conductive films obtained in Examples 1 and 2, instead of the slide glass 10 which is an adherend on the opposite side of a metal oxide conductive film, an acrylic resin plate was used. The results measured using are shown in Table 1 as Control Examples 3 and 4, respectively.

In addition, in the comparative examples 3 and 4, the results measured using the polycarbonate resin plate instead of the acrylic resin plate are shown in Table 1 as the control examples 5 and 6, respectively.

[Table 1]

[week]

BA: Butyl acrylate

2EHA: 2-ethylhexyl acrylate

iBA: isobutyl acrylate

MA: methyl acrylate

CHA: cyclohexyl acrylate

ACMO: acryloyl morpholine

AAc: acrylic acid

HEA: 2-hydroxyethyl acrylate

4HBA: 4-hydroxybutyl acrylate

ITO: tin doped indium oxide

From Table 1, Examples 1 and 2 are the adhesives containing 0.5-10% of acrylic acid units, and since the metal chelate type crosslinking agent is used, the resistance increase rate becomes less than 20%, and is preferable. Comparative Examples 3, 4, and 6 are pressure-sensitive adhesives containing acrylic acid units, but since the storage elastic modulus at 65 ° C is less than 0.1 MPa without the use of an aluminum chelate crosslinking agent, the increase in resistance value is not less than 20%, which is not preferable. Can not do it. Comparative Examples 1, 2, and 5 are pressure-sensitive adhesives containing no acrylic acid unit, and the resistance value increase rate is 20% or more. In addition, Comparative Example 7 is not preferable because the pressure-sensitive adhesive containing an acrylic acid unit or crosslinking agent is not used, and the increase in resistance value is 20% or more since the storage elastic modulus at 65 ° C is less than 0.1 MPa.

In addition, as the results of Comparative Examples 3 to 6 suggest, when the adherend on the opposite side of the metal oxide conductive film is an acrylic resin plate or a polycarbonate resin plate, the increase in resistance value is higher than that in the glass plate, and the superiority of the glass plate is recognized. do.

[Industrial Availability]

The adhesive for the crystalline metal oxide conductive film of the present invention and the adhesive sheet for the crystalline metal oxide conductive film using the same are used for fixing a crystalline metal oxide conductive film such as tin-doped indium oxide (ITO) film and a display device such as an LCD. As the pressure sensitive adhesive and the pressure sensitive adhesive sheet, deterioration of conductive films such as an ITO film, which is an adherend, can be suppressed, and an increase in electric resistance value can be suppressed, and is particularly suitable for a capacitive touch panel.

Claims (10)

(A) 50-99 mass% of acrylic acid alkyl ester units whose C1-C20 alkyl group of (a-1) ester site | part, and (A-2) acrylic acid alkyl ester type copolymer containing 0.5-10 mass% of acrylic acid units The adhesive for crystalline metal oxide conductive film containing 0.01-2 mass parts of (B) metal chelate type crosslinking agents with respect to 100 mass parts of solid substances of the above. The adhesive for crystalline metal oxide conductive film of Claim 1 whose (a-1) acrylic-acid alkyl ester unit is at least a butyl acrylate unit. The pressure-sensitive adhesive for crystalline metal oxide conductive film according to claim 1 or 2, wherein the storage modulus at 65 ° C is 0.10 MPa or more. The adhesive sheet for crystalline metal oxide conductive films which has a layer which consists of an adhesive in any one of Claims 1-3. An adhesive sheet for a crystalline metal oxide conductive film, wherein only the layer made of the adhesive according to any one of claims 1 to 3 is sandwiched between two release sheets. The pressure-sensitive adhesive sheet for crystalline metal oxide conductive film according to claim 4 or 5, wherein the crystalline metal oxide conductive film to be tackified is crystalline tin-doped indium oxide. The adhesive sheet for crystalline metal oxide conductive film of any one of Claims 4-6 used as a member for touch panels. A member for a touch panel comprising at least a layer made of the pressure-sensitive adhesive for a crystalline metal oxide conductive film according to any one of claims 1 to 3 and a crystalline metal oxide conductive film. A touch panel member, which is laminated in order of a glass plate, a layer made of the pressure-sensitive adhesive for a crystalline metal oxide conductive film according to any one of claims 1 to 3, and a crystalline metal oxide conductive film. The member for a touch panel according to claim 8 or 9, wherein the touch panel is capacitive.

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