JP5952470B1 - Adhesive composition for conductive member - Google Patents

Abstract

A pressure-sensitive adhesive composition for a viscous conductive member capable of preventing oxidative deterioration of an adherend when a conductive member such as an ITO film is bonded together even if the pressure-sensitive adhesive composition contains an acidic component such as a carboxyl group. Offer things. A pressure-sensitive adhesive composition containing a (meth) acrylic copolymer having a mass average molecular weight of 100,000 to 1,500,000, wherein the (meth) acrylic copolymer contains a carboxyl group ( It is a copolymer comprising a composition containing 1.2% by mass to 15% by mass of a meth) acrylate or vinyl monomer, and a phosphite compound is added to 100 parts by mass of the (meth) acrylic copolymer. Proposed is a pressure-sensitive adhesive composition for conductive members, comprising 1 × 10 −4 to 8 × 10 −1 parts by mass. [Selection] Figure 1

Description

  The present invention relates to an image display device using an image display panel such as a plasma display (PDP), a liquid crystal display (LCD), an organic EL display (OLED), an electrophoretic display (EPD), an interference modulation display (IMOD), etc. The present invention relates to a pressure-sensitive adhesive composition for a conductive member suitable for bonding conductive members such as a tin-doped indium oxide (referred to as “ITO”) film or an indium / gallium / zinc composite oxide (referred to as “IGZO”) film.

  Image display devices such as personal computers, mobile terminals (PDAs), game machines, televisions (TVs), car navigation systems, touch panels, and pen tablets, such as plasma displays (PDPs), liquid crystal displays (LCDs), organic EL displays (OLEDs), electrophoresis In an image display device using a flat or curved image display panel such as a display (EPD) or an interferometric modulation display (IMOD), no gap is provided between the constituent members for ensuring visibility and preventing damage. In addition, the constituent materials are bonded and integrated with an adhesive sheet or a liquid adhesive.

For example, in an image display device having a configuration in which a touch panel is interposed between the viewing side of the liquid crystal module and the surface protection panel, an adhesive sheet or liquid adhesive is provided between the surface protection panel and the viewing side of the liquid crystal module. The touch panel and other constituent members, for example, the touch panel and the liquid crystal module, and the touch panel and the surface protection panel are bonded and integrated.
The touch panel usually includes an upper electrode plate and a lower electrode plate having a transparent conductive film formed from a metal oxide such as ITO or IGZO. These metal oxide films are highly corrosive and corrode by the outgas of the adhesive material or the acid component derived from the elution component under high temperature or moist heat environment. In some cases, the electrode may be disconnected.

  By the way, when determining the composition and preparation method of pressure-sensitive adhesive sheets and liquid pressure-sensitive adhesives, in order to impart basic physical properties as pressure-sensitive adhesive materials such as adhesive strength and cohesive strength, high-polarity components such as carboxyl groups are added as copolymerization components or additions. It is generally carried out as an agent. However, since such highly polar components have an oxidizing action, the pressure-sensitive adhesive sheet may cause oxidative deterioration of the adherend due to an environment such as high temperature and high humidity or long-term storage. Such oxidative deterioration of the adherend has to be particularly noted when a conductive member having a portion made of a conductive member such as an ITO film or an IGZO film is bonded.

  Then, in view of such a problem, the proposal which suppresses the oxidative degradation of a to-be-adhered body is made | formed by not introduce | transducing acidic components, such as a carboxyl group, into an adhesive composition. For example, Patent Document 1 discloses an acrylic polymer having a mass average molecular weight of 400,000 to 1.6 million comprising an alkoxyalkyl acrylate (component A) and an acrylic monomer having a hydroxyl group (component B) as essential monomer components. A pressure-sensitive adhesive composition is disclosed.

Further, in Patent Document 2, a single amount of (meth) acrylic acid ester is based on the fact that the corrosion degradation of the adherend can be effectively suppressed by blending a specific acrylic polymer and a specific amine compound having polarity. An acrylic polymer obtained by polymerization or copolymerization as a body, and a formula (1) ·· CH ₂ ═CH (R ₁ ) —XN (R ₂ ) (R ₃ ) (wherein R ₁ is hydrogen or methyl R ₂ and R ₃ are each independently hydrogen or a hydrocarbon group having 1 to 6 carbon atoms, and X is C (═O) (R ₄ ), O (R ₄ ), COO (R ₄ ). , OCO (R ₄ ), CONH (R ₄ ), C (═O), O, COO, OCO, and CONH, wherein R 4 is a hydrocarbon group having 1 to 6 carbon atoms. Formed from a pressure-sensitive adhesive composition containing the amine compound represented Transparent double-sided pressure-sensitive adhesive sheet, wherein there is disclosed.

JP 2010-215923 A JP 2012-246407 A

  As disclosed in the above-mentioned Patent Document 1, if an acidic component such as a carboxyl group is not introduced into the pressure-sensitive adhesive composition, the pressure-sensitive adhesive property is lowered or the optical properties such as transparency are lowered. It has been difficult to maintain the characteristics of a conventional pressure-sensitive adhesive composition that contains an acidic component such as a carboxyl group.

  Therefore, the present invention provides an oxidation resistance capable of preventing oxidative deterioration of these adherends when a conductive member such as an ITO film is bonded even if the pressure-sensitive adhesive composition contains an acidic component such as a carboxyl group. It is intended to provide a new pressure-sensitive adhesive composition for viscous conductive members which is excellent in the above.

The present invention is a pressure-sensitive adhesive composition containing a (meth) acrylic copolymer having a mass average molecular weight of 100,000 to 1,500,000, and the (meth) acrylic copolymer contains a carboxyl group ( It is a copolymer comprising a composition containing 1.2% by mass to 15% by mass of a meth) acrylate or vinyl monomer, and a phosphite compound is added to 100 parts by mass of the (meth) acrylic copolymer. 1 × 10 ⁻⁴ to 8 × 10 ⁻¹ parts by mass A conductive composition pressure-sensitive adhesive composition is proposed.

  The pressure-sensitive adhesive composition for conductive members proposed by the present invention comprises a predetermined (meth) acrylic copolymer as a base resin, that is, 1.2% by mass to 15% of a (meth) acrylate or vinyl monomer containing a carboxyl group. By adding a predetermined amount of a phosphite compound to the (meth) acrylic copolymer contained by mass%, even if the pressure-sensitive adhesive composition contains an acidic component such as a carboxyl group, It is possible to prevent oxidative deterioration of the conductive member that is the adherend, and to exert a surprising corrosion inhibiting effect. Therefore, the pressure-sensitive adhesive composition for conductive members proposed by the present invention can be used as a pressure-sensitive adhesive composition suitable for bonding various conductive members.

It is a figure for demonstrating the evaluation test method of the corrosion-resistant reliability performed in the Example mentioned later, (A) is a top view of the ITO pattern of the ITO glass substrate for corrosion-resistant reliability evaluation, (B) is resistance-proof. The top view which showed the state which coat | covered the adhesive sheet on the ITO glass substrate for corrosion reliability evaluation, (C) is sectional drawing of the sample for corrosion resistance reliability evaluation.

  Next, a description will be given based on an embodiment for carrying out the present invention. However, the present invention is not limited to the embodiment described below.

<This pressure-sensitive adhesive composition>
The pressure-sensitive adhesive composition according to this embodiment (hereinafter referred to as “the pressure-sensitive adhesive composition”) includes a (meth) acrylic copolymer, a phosphite compound, and a crosslinking agent as necessary. It is a pressure-sensitive adhesive composition containing a crosslinking initiator as required and further containing other materials as necessary.

(Phosphite compound)
The phosphite compound itself is not corrosive in itself, but can stabilize acid components such as carboxyl groups, so this adhesive with a predetermined (meth) acrylic copolymer as the base resin. By blending a predetermined amount of a phosphite compound into the adhesive composition, even if the pressure-sensitive adhesive composition contains an acid component, it is possible to prevent oxidative deterioration of the conductive member that is the adherend. Of course, if the pressure-sensitive adhesive composition does not contain an acid component, it is possible to prevent oxidative deterioration of the conductive member as the adherend.

The phosphite compound contained in the present pressure-sensitive adhesive composition is preferably a phosphite compound represented by the following formula (1).
P [—OR] ₃ (wherein R is a hydrocarbon such as a substituted or unsubstituted aromatic, an alicyclic ring and an alkyl group. The plurality of R may be the same or different from each other) And a plurality of adjacent Rs may be bonded to each other to form a saturated or unsaturated ring structure.)
Further, it may be a compound containing two or more structural units represented by the above formula (1).

As a result of testing various pressure-sensitive phosphite compounds represented by the above formula (1) in a pressure-sensitive adhesive composition based on a predetermined (meth) acrylic copolymer, any phosphite It was confirmed that the compound also showed an effect of preventing oxidative degradation.
Among them, the phosphite compound contained in the present adhesive composition includes, for example, triphenyl phosphite, trisnonylphenyl phosphite, tricresyl phosphite, tristearyl phosphite, triethyl phosphite, phosphorus phosphite Tris (2-ethylhexyl) acid, tridecyl phosphite, trilauryl phosphite, tris phosphite (tridecyl) phosphite, trioleyl phosphite, diphenyl phosphite (2-ethylhexyl), diphenyl monodecyl phosphite, Diphenyl mono (tridecyl) phosphate, tetraphenyl dipropylene dipropylene glycol diphosphite, tetraphenyl (tetratridecyl) pentaerythritol tetraphosphite, tetra (C12-C15 alkyl) -4,4-isopropylidene diphenyl diphosphite , Phosphorous acid Lis (2,4-di-t-butylphenyl), tris (4-nonylphenyl) phosphite, 3,9-bis (nonylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5,5] Undecane, 3,9-bis (4-nonylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5,5] undecane, 3,9-bis (decyloxy)- 2,4,8,10-tetraoxa-3,9-diphosphaspiro [5,5] undecane, 3,9-bis (tridecyloxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5 , 5] undecane, 3,9-bis (stearyloxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5,5] undecane, 3,9-bis (2,6-di-tert) -Butyl-4-methylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5,5] undecane, 3,9-bis (2,4-di-tert-butylphenoxy) -2 , 4,8,10-tetraoxa-3,9-diphosphaspiro [5,5] undecane, 3,9-bis {2,4-bis (1-methyl-1-phenylethyl) phenoxy} -2,4,8 , 10-tetraoxa-3,9-diphosphaspiro [5,5] undecane, 2,2'-methylenebis (4,6-di-tert-butyl-1-phenyloxy) phosphite, 4,4'-isopropylidene Phenol C12-15 alcohol phosphite, distearyl pentaerythritol diphosphite, 2,4,8,10-tetrakis (1,1-dimethylethyl) -6- { 2-ethylhexyl) oxy} -12H-dibenzo [d, g] [1,3,2] dioxaphosphine, 2,4,8,10-tetrakis (1,1-dimethylethyl) -6- (tri Decyloxy) -12H-dibenzo [d, g] [1,3,2] dioxaphosphine, 1,1′-biphenyl-4,4′-diylbis [bis (2,4-di-phosphite) t-butylphenyl)], hydrogenated bisphenol A / pentaerythritol phosphite polymer, hydrogenated bisphenol A phosphite polymer, diethyl phosphite, bis (2-ethylhexyl) phosphite, dilauryl phosphite, dioleyl phosphite , Diphenyl phosphite, and the like are particularly preferable.

  Among these, in consideration of the physical properties of the phosphite compound contained in the present pressure-sensitive adhesive composition, for example, in consideration of compatibility with the acrylic resin composition, aliphatic phosphite esters (for example, phosphorous acid of Example 2) As the acid ester compound, tridecyl phosphite and 3,9-bis (decyloxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane of Example 3) are preferable. In consideration of hydrolysis resistance, an aromatic phosphite ester (for example, tris (2,4-di-t-butylphenyl) phosphite as the phosphite compound of Example 1) is preferable. In consideration of the balance between solubility and hydrolysis resistance, a compound having both an aliphatic ester group and an aromatic ester group such as diphenyl phosphite mono (tridecyl) is preferable.

In the present pressure-sensitive adhesive composition, the content ratio of the phosphite compound does not impair the pressure-sensitive adhesive performance, and from the viewpoint of more effectively suppressing the oxidative deterioration of a conductive member such as an ITO film, The phosphite compound is preferably contained in a proportion of 0.0001 (1 × 10 ⁻⁴ ) to 0.8 (8 × 10 ⁻¹ ) parts by mass with respect to 100 parts by mass of the (meth) acrylic copolymer. In particular, it is more preferably 0.0005 parts by mass or more and 0.7 parts by mass or less, and particularly preferably 0.001 part by mass or more or 0.6 parts by mass or less.

((Meth) acrylic copolymer)
In this pressure-sensitive adhesive composition, the (meth) acrylic copolymer as the base resin contains a linear or branched alkyl (meth) acrylate having 4 to 18 carbon atoms in the side chain and a carboxyl group (meth). A copolymer comprising a composition containing an acrylate or vinyl monomer, or a (meth) acrylate or vinyl monomer having 1 to 3 carbon atoms in the side chain and / or a (meth) acrylate or vinyl containing a hydroxyl group Mention may be made of a copolymer comprising a composition containing a monomer.

In this case, examples of the linear or branched alkyl (meth) acrylate having 4 to 18 carbon atoms in the side chain include n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t- Butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, neopentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, decyl (meth) acrylate, isodecyl ( Acrylate), undecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, isobornyl (meth) ) Acrylate, 3,5,5-trimethylcyclohexane (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.
The linear or branched alkyl (meth) acrylate having 4 to 18 carbon atoms in the side chain is preferably contained in an amount of 30 parts by mass or more and 90 parts by mass or less with respect to 100 parts by mass of the copolymer. Alternatively, it is more preferably 88 parts by mass or less, and particularly preferably 40 parts by mass or more or 85 parts by mass or less.

The (meth) acrylate or vinyl monomer containing a carboxyl group is 1.2 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the copolymer, and particularly 1.5 parts by mass or more from the viewpoint of obtaining excellent adhesive properties. Alternatively, it is preferably 10 parts by mass or less, particularly preferably 2 parts by mass or more or 8 parts by mass or less.
On the other hand, the (meth) acrylate or vinyl monomer containing a hydroxyl group is preferably contained in an amount of 0 to 30 parts by mass with respect to 100 parts by mass of the copolymer. Among these, it is more preferable to contain 0 part by mass or more and 20 parts by mass or less.

  Further, the (meth) acrylate or vinyl monomer having 1 to 3 carbon atoms in the side chain is preferably contained in an amount of 0 to 70 parts by mass with respect to 100 parts by mass of the copolymer. Alternatively, it is more preferably 65 parts by mass or less, particularly preferably 5 parts by mass or more or 60 parts by mass or less.

  In addition to the above, acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride, glycidyl (meth) acrylate, glycidyl α-ethyl acrylate, epoxy such as 3,4-epoxybutyl (meth) acrylate Group-containing monomer, amino group-containing (meth) acrylic acid ester monomer such as dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) acrylamide, Nt-butyl (meth) acrylamide, N-methylol Monomers containing amide groups such as (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone (meth) acrylamide, maleic acid amide, maleimide, vinyl pyrrolidone, vinyl pyridine, Vinylca Heterocyclic basic monomers such as vazole, and various vinyl monomers such as styrene, t-butylstyrene, α-methylstyrene, vinyltoluene, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate, and alkyl vinyl ether are also required. It can be used as appropriate.

  Specific examples of the (meth) acrylic copolymer include, for example, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, isostearyl (meth) acrylate, butyl (meth) acrylate, ethyl Monomer component (a) such as (meth) acrylate, methyl (meth) acrylate and the like, meth) acrylic acid having a carboxyl group, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxy Propylhexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxypropyl phthalic acid, 2- (meth) acryloyloxyethyl maleic acid, 2- (meth) acryloyloxypropyl maleic acid, 2- (Meth) acryloyloxy Hydroxyethyl (meth) acrylate having monomer components (b) such as ethyl succinic acid, 2- (meth) acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, and hydrophilic and organic functional groups , Hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, glycerol (meth) acrylate, (monomethyl maleate, monomethyl itaconate, vinyl acetate, glycidyl (meth) acrylate, (meth) acrylamide, (meth) acrylonitrile, fluorine Mention may be made of (meth) acrylic acid ester copolymers obtained by copolymerizing monomeric components (c) such as fluorinated (meth) acrylates and silicone (meth) acrylates.

  As a (meth) acrylic copolymer, acrylic acid is copolymerized such as a (meth) acrylic copolymer that is a copolymer of a monomer having a carboxyl group and a (meth) acrylic ester. When the (meth) acrylic copolymer formed is used, it is rich in cohesive strength and adhesive strength, and can exhibit suitable physical properties as an adhesive material. When applied to an adherend having a conductive member, the adherend may be oxidized and deteriorated. However, as described above, in the case of the present pressure-sensitive adhesive composition, since the phosphite compound is contained, the problem of such corrosion is reduced.

The weight average molecular weight of the (meth) acrylic copolymer is preferably 100,000 to 1,500,000, more preferably 150,000 or more and 1.3 million or less, and particularly preferably 200,000 or more or 1,200,000 or less.
In order to obtain a pressure-sensitive adhesive composition having a high cohesive force, the mass average molecular weight is 700,000 to 1,500,000, particularly 800,000 or more, or 1.3 million from the viewpoint of obtaining cohesive force due to entanglement of molecular chains as the molecular weight of the base polymer increases. It is preferable that: On the other hand, when it is desired to obtain an adhesive composition having high fluidity and stress relaxation properties, the mass average molecular weight is preferably 100,000 to 700,000, particularly 200,000 or more or 600,000 or less.
In addition, when a solvent is not used when molding an adhesive sheet or the like, it is difficult to use a base polymer having a large molecular weight, so the mass average molecular weight of the (meth) acrylic copolymer is 100,000 to 700,000. In particular, it is preferably 200,000 or more or 600,000 or less, and particularly preferably 250,000 or more or 500,000 or less.

(Crosslinking agent, crosslinking initiator)
The present pressure-sensitive adhesive composition can be prepared so as to crosslink the (meth) acrylic copolymer by blending a crosslinking agent or a crosslinking initiator as necessary.
For example, when the above (meth) acrylic acid ester (co) polymer is cross-linked, a cross-linking agent capable of chemically bonding with a reactive group such as a hydroxyl group or a carboxyl group introduced into the acrylic acid ester (co) polymer. And adding a reaction initiator such as a polyfunctional (meth) acrylate having two or more (meth) acryloyl groups as a crosslinking agent and a photocrosslinking initiator as a crosslinking agent, ultraviolet irradiation, etc. A method of cross-linking can be mentioned.
Among them, a crosslinking method by irradiation with light such as ultraviolet rays is preferable from the viewpoint that the polar functional group such as a carboxyl group in the pressure-sensitive adhesive composition is not reacted and consumed and a high cohesive force derived from the polar component and the pressure-sensitive adhesive properties can be maintained.

  Examples of the crosslinking agent include at least one selected from (meth) acryloyl group, epoxy group, isocyanate group, carboxyl group, hydroxyl group, carbodiimide group, oxazoline group, aziridine group, vinyl group, amino group, imino group, and amide group. The crosslinking agent which has these crosslinking | crosslinked functional groups can be mentioned, You may use combining 1 type (s) or 2 or more types. The crosslinkable functional group may be protected with a deprotectable protecting group.

Moreover, when performing bridge | crosslinking by light irradiation, it is preferable to contain a photoinitiator.
Radical generation mechanisms by photopolymerization initiators are roughly classified into two types: α-cleavage type that cleaves and decomposes its own single bond to generate radicals, and hydrogen abstraction that excites hydrogen from compounds in the system to generate radicals. There is a type. Among these, it is preferable to use a hydrogen abstraction type photocrosslinking initiator.

The content of the crosslinking agent is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the (meth) acrylic copolymer from the viewpoint of balancing the flexibility and cohesive force of the pressure-sensitive adhesive composition. Of these, 0.05 parts by mass or more and 8 parts by mass or less, and particularly preferably 0.1 parts by mass or more and 5 parts by mass or less.
When an organic crosslinking agent having a (meth) acryloyl group is used, it is preferable to further add a photopolymerization initiator. This is because radicals are generated by light irradiation and become the starting point of the polymerization reaction in the system.

  The addition amount of the photopolymerization initiator is not particularly limited, and is generally 0.1 to 10 parts by mass, particularly 0.2 parts by mass or more with respect to 100 parts by mass of the (meth) acrylic copolymer. Alternatively, it is particularly preferably adjusted at a ratio of 5 parts by mass or less, and more preferably 0.5 parts by mass or more or 3 parts by mass or less. However, this range may be exceeded in balance with other elements.

In addition to the above, an antioxidant may be added as necessary. Examples of the antioxidant include 2,2′-methylenebis (4-methyl-6-tert-butylphenol), hexamethylene glycol-bis (3,5-di-tert-butyl-4-hydroxyhydrocinnamate), tetrakis [Methylene (3,5-di-tert-butyl-4-hydroxyhydrocinnamate)] methane, triethylene glycol-bis-3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionate, 1 , 3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxy-benzyl) benzene, n-octadecyl-3- (4′-hydroxy-3 ′, 5 ′ -Di-t-butylphenol) propionate, 4,4'-methylenebis (2,6-di-t-butylphenol), 4,4'-butylidene-bis- (6-t- Chill -3-methyl - phenol) and hindered phenol antioxidants such as, sulfur-based, include various antioxidants amine and the like.
Furthermore, you may contain the well-known component mix | blended with a normal adhesive composition suitably. For example, light stabilizer, ultraviolet absorber, metal deactivator, rust inhibitor, anti-aging agent, hygroscopic agent, foaming agent, antifoaming agent, inorganic particles, viscosity modifier, tackifier resin, photosensitizer Various additives such as fluorescent agents and reaction catalysts (tertiary amine compounds, quaternary ammonium compounds, tin laurate compounds, etc.) can be appropriately contained.

The pressure-sensitive adhesive composition can be prepared using a solvent, but can also be prepared as a hot-melt pressure-sensitive adhesive composition that does not use a solvent.
A hot-melt pressure-sensitive adhesive composition that does not use a solvent can be thicker than a pressure-sensitive adhesive composition that uses a solvent, and therefore fills the gaps between the constituent members of the image display device. Can be thick enough.
The method for forming the pressure-sensitive adhesive sheet is not particularly limited. For example, the melted pressure-sensitive adhesive composition can be formed into a sheet using coating, cast molding, rolling molding, or the like. After the mixture of the pressure-sensitive adhesive composition and the organic solvent is applied to the substrate, it may be formed into a sheet using a method of removing the solvent.

<Features>
This pressure-sensitive adhesive composition has an effect of preventing oxidative degradation. Therefore, the rate of change [((Ω / Ω ₀ ) -1) × 100] of the ITO resistance value measured by the following methods (1) to (2) can be less than 5%, particularly less than 3%. .

(1) An adhesive ITO composition for conductive members is formed into a sheet having a thickness of 150 μm to form an adhesive sheet, and an ITO glass substrate for evaluation in which an ITO wiring made of indium oxide (ITO) is formed on a glass substrate. The adhesive sheet is bonded to create an ITO wiring with an adhesive sheet.
(2) The resistance value (Ω ₀ ) at room temperature of the ITO wiring in the ITO wiring with the adhesive sheet is measured in advance, and the ITO wiring with the adhesive sheet is stored in an environment of 65 ° C. and 90% RH for 800 hours. The resistance value (Ω) after the storage of the ITO wiring in the ITO wiring with the adhesive sheet is measured.

<Form of the present adhesive composition>
The pressure-sensitive adhesive composition may be liquid, gel, or paste. Moreover, a sheet form may be sufficient.

The pressure-sensitive adhesive sheet obtained by forming the pressure-sensitive adhesive composition into a film (“the pressure-sensitive adhesive sheet”) can be produced as follows.
For example, the pressure-sensitive adhesive composition is formed on the release-treated surface of a release film for a process such as a release PET so as to have a desired thickness, and subjected to a treatment such as heating or ultraviolet irradiation as necessary for crosslinking. It can be obtained by advancing the reaction.

The pressure-sensitive adhesive sheet is preferably optically transparent. That is, it is preferably a transparent adhesive sheet. Here, “optically transparent” means that the total light transmittance is 80% or more, preferably 85% or more, and more preferably 90% or more.
The thickness of the pressure-sensitive adhesive sheet is preferably 10 μm to 500 μm, more preferably 15 μm or more and 400 μm or less, and particularly preferably 20 μm or more or 350 μm or less.

  Thus, this pressure-sensitive adhesive sheet can also be used as a pressure-sensitive adhesive sheet laminate having a configuration in which release films are laminated on both sides of the sheet.

<Uses of the present adhesive composition>
The pressure-sensitive adhesive composition is, for example, an image display device such as a personal computer, a mobile terminal (PDA), a game machine, a television (TV), a car navigation system, a touch panel, a pen tablet, such as a plasma display (PDP), a liquid crystal display (LCD), an organic In an image display device using an image display panel such as an EL display (OLED), an electrophoretic display (EPD), an interferometric modulation display (IMOD), etc., each component member, particularly a conductive member, particularly a conductive material including ITO (indium oxide). It is suitable for bonding the structural member provided with the member. Among these, from the viewpoint of corrosion reliability that does not cause oxidative degradation of the adherend, it is particularly suitable for bonding a touch panel having electrodes that are susceptible to oxidative degradation, such as a transparent conductive material such as an ITO film or an IGZO film.
For example, the transparent conductive laminated body for touchscreens using this adhesive sheet can be produced.

  Specifically, in an image display device having a configuration in which a touch panel is interposed between the viewing side of the liquid crystal module and the surface protection panel, the liquid crystal module is disposed between the surface protection panel and the viewing side of the liquid crystal module, It is particularly useful for bonding a touch panel and other components such as a touch panel and a liquid crystal module, or a touch panel and a surface protection panel. That is, it is preferably disposed between the surface protection panel in the image display device and the viewing side of the liquid crystal module, and used for adhering and integrating the two members. More preferably, at least one member is a touch panel.

Incidentally, a normal touch panel is provided with an upper electrode plate and a lower electrode plate having a transparent conductive film formed from a metal oxide such as ITO or IGZO. These metal oxide films are highly corrosive and corrode by the outgas of the adhesive material or the acid component derived from the elution component under high temperature or moist heat environment. In some cases, the electrode may be disconnected.
However, as described above, since this adhesive sheet has a reduced corrosive action, it is attached so that one surface is in contact with the touch panel, and is attached to another member on the other surface. It is preferable to use it.

  As the surface protection panel, synthetic resin plates made of polycarbonate resin, acrylic resin, alicyclic polyolefin resin, styrene resin, polyvinyl chloride resin, phenol resin, melamine resin, epoxy resin, etc. And a glass plate.

  For example, an image display device having a configuration in which a touch panel is interposed between the viewing side of the liquid crystal module and the surface protection panel, and the touch panel is bonded to another component using the present adhesive sheet An image display device (referred to as “the present image display device”) having the following configuration can be configured.

  As described above, the image display device has a configuration in which the adhesive sheet with reduced corrosive action is adhered and integrated so as to come into contact with the touch panel, so that a metal such as ITO or IGZO is used. The transparent conductive film made of an oxide has an advantage that there is no fear that the electrode is broken due to corrosion by an acid component derived from the pressure-sensitive adhesive sheet.

<Explanation of phrases>
“Sheet” generally refers to a product that is thin by definition in JIS and has a thickness that is small and flat for the length and width. In general, “film” is thicker than the length and width. A thin flat product with an extremely small thickness and an arbitrarily limited maximum thickness, usually supplied in the form of a roll (Japanese Industrial Standard JISK6900). However, since the boundary between the sheet and the film is not clear and it is not necessary to distinguish the two in terms of the present invention, in the present invention, even when the term “film” is used, the term “sheet” is included and the term “sheet” is used. In some cases, “film” is included.
In addition, the expression “panel” such as an image display panel and a protection panel includes a plate, a sheet, and a film.

In the present specification, when “X to Y” (X and Y are arbitrary numbers) is described, it means “preferably greater than X” or “preferably,” with the meaning of “X to Y” unless otherwise specified. The meaning of “smaller than Y” is also included.
Further, when described as “X or more” (X is an arbitrary number), it means “preferably larger than X” unless otherwise specified, and described as “Y or less” (Y is an arbitrary number). In the case, unless otherwise specified, the meaning of “preferably smaller than Y” is also included.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to these.

[Example 1]
Tris phosphite as a phosphite compound for 1 kg of a copolymer consisting of 76 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of vinyl acetate and 4 parts by mass of acrylic acid (A-1, mass average molecular weight 400,000) 5 g of (2,4-di-t-butylphenyl) (B-1) (“Irgaphos 168” manufactured by BASF) and 20 g of 4-methylbenzophenone as a photopolymerization initiator were added and mixed uniformly to form an adhesive composition. Product 1 was obtained. The copolymer (A-1) was a copolymer containing 4% by mass of a (meth) acrylate or vinyl monomer containing a carboxyl group.
Next, a release-treated polyethylene terephthalate film (Mitsubishi Resin, Diafoil MRV, thickness 100 μm) and a release-treated polyethylene terephthalate film (Mitsubishi Resin, Diafoil MRQ, thickness 75 μm) The pressure-sensitive adhesive composition 1 was sandwiched and shaped into a sheet using a laminator to a thickness of 150 μm.
The pressure-sensitive adhesive composition 1 was cured by irradiating the pressure-sensitive adhesive composition 1 with ultraviolet light so that the light having a wavelength of 365 nm reached 2000 mJ / cm ² through the peeled polyethylene terephthalate film. .

[ Reference Example 1 ]
Tridecyl phosphite (B-) as a phosphite compound is used for 1 kg of a copolymer consisting of 81 parts by mass of butyl acrylate, 15 parts by mass of methyl methacrylate and 4 parts by mass of acrylic acid (A-2, mass average molecular weight 300,000). 2) 1 g (“Adeka Stub 3010” manufactured by Adeka), 50 g of glycerin dimethacrylate (C-1) (manufactured by Shin-Nakamura Chemical Co., Ltd., NK ester 701) as a crosslinking agent, Irgacure 184 (manufactured by BASF) as a photopolymerization initiator 10 g and 2 g of Irganox 1010 (manufactured by BASF) as an antioxidant were added and mixed uniformly to obtain an adhesive composition 2. The copolymer (A-2) was a copolymer containing 4% by mass of a (meth) acrylate or vinyl monomer containing a carboxyl group.
Next, the pressure-sensitive adhesive composition 2 was molded into a sheet shape so as to have a thickness of 150 μm on a polyethylene terephthalate film (Mitsubishi Resin, Diafoil MRV, thickness 100 μm) subjected to release treatment, and then subjected to release treatment. A terephthalate film (manufactured by Mitsubishi Plastics, Diafoil MRQ, thickness 75 μm) was coated. The pressure-sensitive adhesive composition was cured by irradiating it with ultraviolet rays so that light having a wavelength of 365 nm reached 1000 mJ / cm ² through the polyethylene terephthalate film subjected to the release treatment, and pressure-sensitive adhesive sheet 2 was obtained.

[ Reference Example 2 ]
With respect to 1 kg of solid content of an ethyl acetate diluted solution of acrylic copolymer (A-3, mass average molecular weight 500,000) consisting of 74 parts by mass of butyl acrylate, 24 parts by mass of 2-ethylhexyl acrylate, and 2 parts by mass of acrylic acid, 3,9-bis (decyloxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane (B-3) (“JPE-10” manufactured by Johoku Chemical Co., Ltd.) ) And 0.5 g of TETRAD-X (C-2) (Mitsubishi Gas Chemical Co., Ltd.) as an amine-based crosslinking agent were added and mixed uniformly to prepare an adhesive composition 3. The copolymer (A-3) was a copolymer containing 2% by mass of a (meth) acrylate or vinyl monomer containing a carboxyl group.
Next, the adhesive composition 3 was applied on a polyethylene terephthalate film (Mitsubishi Resin, Diafoil MRV, thickness 100 μm) subjected to a release treatment so that the thickness after drying was 50 μm, and then at 70 ° C. It was dried for 5 minutes to obtain a sheet-like pressure-sensitive adhesive composition having a thickness of 50 μm. After three layers were laminated to a thickness of 150 μm, a peeled polyethylene terephthalate film (manufactured by Mitsubishi Plastics, Diafoil MRQ, thickness 75 μm) was coated. This was cured at room temperature (23 ° C.) for 7 days to react with the cross-linking agent, and the pressure-sensitive adhesive sheet 3 was prepared.

[Example 4]
Phosphorous acid with respect to 1 kg of solid content of a pressure-sensitive adhesive solution (manufactured by Soken Chemical Co., Ltd., SK Dyne 1882, solid content concentration of about 17%) made of a commercially available acrylic copolymer (A-4, mass average molecular weight 1.3 million) 0.7 g of tris (2,4-di-t-butylphenyl) phosphite (B-1) (BASF “Irgaphos 168”) as an ester compound and L-45 (C-3 as an isocyanate-based crosslinking agent) ) (Manufactured by Soken Chemical Co., Ltd.) 1.85 g and 0.5 g of E-5XM (C-4) (manufactured by Soken Chemical Co., Ltd.) as an epoxy crosslinking agent were added and mixed uniformly to prepare an adhesive composition 4. . The copolymer (A-4) was a copolymer containing 3 ± 1% by mass of a (meth) acrylate or vinyl monomer containing a carboxyl group.
Next, the adhesive composition 4 was applied on a polyethylene terephthalate film (Mitsubishi Resin, Diafoil MRV, thickness 100 μm) subjected to a release treatment so that the thickness after drying was 50 μm, and then at 70 ° C. It was dried for 5 minutes to obtain a sheet-like pressure-sensitive adhesive composition having a thickness of 50 μm. After three layers were laminated to a thickness of 150 μm, a peeled polyethylene terephthalate film (manufactured by Mitsubishi Plastics, Diafoil MRQ, thickness 75 μm) was coated. This was cured at room temperature (23 ° C.) for 7 days to react with the cross-linking agent, and the pressure-sensitive adhesive sheet 4 was prepared.

[Comparative Example 1]
An adhesive composition 5 and an adhesive sheet 5 were prepared in the same manner as in Example 1 except that the phosphite compound (B-1) was not added.

[Comparative Example 2]
A pressure-sensitive adhesive composition 6 and a pressure-sensitive adhesive sheet 6 were prepared in the same manner as in Reference Example 1 , except that the amount of the phosphite compound (B-2) (“Adeka Stub 3010” manufactured by Adeka Corporation) was 10 g.

[Comparative Example 3]
Instead of the phosphite compound (B-1), a mixture (B-4) of dihydrogen phosphate octadecyl phosphate and bisoctadecyl phosphate (“ADEKA STAB AX-71” manufactured by Adeka Corporation), which is a phosphate ester compound. Except having used, the adhesive composition 7 and the adhesive sheet 7 were created similarly to Example 1. FIG.

[Comparative Example 4]
Glycerin dimethacrylate (C-1) (Shin Nakamura Chemical Co., Ltd.) as a cross-linking agent for 1 kg of a copolymer (A-5, mass average molecular weight 700,000) consisting of 70 parts by mass of 2-ethylhexyl acrylate and 30 parts by mass of vinyl acetate 50 g of NK ester 701) and 10 g of Irgacure 184 as a photopolymerization initiator were added and mixed uniformly to obtain an adhesive composition 8.
The pressure-sensitive adhesive composition 8 was formed into a sheet shape having a thickness of 150 μm on a peel-treated polyethylene terephthalate film (Mitsubishi Resin, Diafoil MRV, thickness 100 μm), and then peel-treated polyethylene terephthalate film (Mitsubishi). Resin Co., Ltd., Diafoil MRQ, thickness 75 μm) was coated. The pressure-sensitive adhesive composition was cured by irradiating it with ultraviolet rays so that light having a wavelength of 365 nm reached 1000 mJ / cm ² through the polyethylene terephthalate film subjected to the release treatment, whereby a pressure-sensitive adhesive sheet 8 was obtained.

[Comparative Example 5]
Samples were prepared with reference to the examples of JP2013-18892A. That is, the solid content of the ethyl acetate dilution liquid (A-6) of a copolymer comprising 60 parts by mass of methoxyethyl acrylate, 34 parts by mass of butyl acrylate, 4 parts by mass of 2-hydroxyethyl acrylate, and 2 parts by mass of dimethylaminoethyl acrylate 3 g of trimethylolpropane adduct type hexamethylene diisocyanate (C-5) was mixed as a crosslinking agent with respect to 1 kg to obtain a pressure-sensitive adhesive composition 9.
The obtained pressure-sensitive adhesive composition 9 was applied onto a polyethylene terephthalate film (Mitsubishi Resin Co., Ltd., Diafoil MRV, thickness: 100 μm) subjected to a release treatment so that the thickness after drying was 50 μm, at 80 ° C. The solvent was removed by drying for 2 minutes to form an adhesive layer. After three layers were laminated to a thickness of 150 μm, a peeled polyethylene terephthalate film (manufactured by Mitsubishi Plastics, Diafoil MRQ, thickness 75 μm) was coated. The pressure-sensitive adhesive sheet 9 was prepared by curing at 23 ° C. for 7 days.

<Evaluation>
[Adhesive force]
For the pressure-sensitive adhesive sheets prepared in Examples and Comparative Examples, one release film was peeled off, and a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd .; trade name “Cosmo Shine A4300”, thickness 100 μm) was roll-bonded with a hand roller as a backing film. . This was cut into a 10 mm wide × 100 mm long strip, and the remaining peeled film was peeled off, and the adhesive surface exposed by roll-sticking to soda lime glass using a hand roller. After normal curing for 24 hours, the pressure-sensitive adhesive sheet was peeled from the glass while pulling the backing film at an angle of 180 ° at a peeling speed of 60 mm / min, and the tensile strength was measured with a load cell. The peel strength was measured and shown in Table 1 as “Glass Adhesive Strength”.

[Optical reliability]
The release film on one side of the pressure-sensitive adhesive sheet prepared in Examples and Comparative Examples was peeled off, and a PET film (Toyobo Co., Ltd., Cosmo Shine A4300, 100 μm) was attached to the exposed surface with a hand roller. Next, after cutting out the said adhesive sheet to 50 mm x 80 mm, the remaining peeling film was peeled off, it stuck on the soda-lime glass of thickness 0.5mm with the hand roller, and the sample for optical reliability evaluation was created.
About the said sample for evaluation, the total light transmittance was measured according to JISK7361-1 using the haze meter NDH5000 (made by Nippon Denshoku Industries Co., Ltd.).

Further, the sample for evaluation was stored for 3 days under moist and heat conditions of 65 ° C. and 90% RH, taken out, and a sample for optical reliability evaluation after 2 hours was used with a haze meter NDH5000 (manufactured by Nippon Denshoku Industries Co., Ltd.). The haze value was measured according to K7136, and is shown in Table 1 as “wet heat haze”.
A sample having a haze value exceeding 10% was determined as “× (poor)”, and a sample having a haze value of 10% or less was determined as “◯ (good)”.

[Corrosion resistance reliability]
On a glass substrate (60 mm × 45 mm), a reciprocal line of indium oxide (ITO) is formed so as to reciprocate 10.5 with a thickness of 15 to 20 nm, a line width of 70 μm, a line length of 46 mm, and a line interval of 30 μm. A 2 mm square made of ITO was formed on both ends of the reciprocating line to form an ITO pattern (length: about 97 cm), and an ITO glass substrate for corrosion resistance reliability evaluation was created (see FIG. 1A). .
The release film on one side of the pressure-sensitive adhesive sheets 1 to 9 (thickness 150 μm) prepared in Examples and Comparative Examples is peeled off, and a PET film (manufactured by Toyobo Co., Ltd., Cosmo Shine A4100, 125 μm) is attached to the exposed surface with a hand roller. I wore it. Next, after cutting out the pressure-sensitive adhesive sheet to 40 mm × 45 mm, the remaining release film is peeled off, and as shown in FIG. 1B, the corrosion resistance reliability evaluation is performed so as to cover the length of 40 mm on the ITO reciprocating line. An adhesive sheet was adhered to the ITO glass substrate for use with a hand roller to prepare a corrosion resistance reliability evaluation sample (ITO wiring with adhesive sheet) (see FIG. 1 (C)).

The resistance value (Ω ₀ ) at room temperature of the ITO wiring in this corrosion resistance reliability evaluation sample (ITO wiring with adhesive sheet) was measured in advance.
On the other hand, the corrosion resistance reliability evaluation sample (ITO wiring with adhesive sheet) is stored in an environment of 65 ° C. and 90% RH for 800 hours, and after storage, in the corrosion resistance reliability evaluation sample (ITO wiring with adhesive sheet) The resistance value (Ω) of the ITO wiring was measured.
Then, the change rate (%) [((Ω / Ω ₀ ) −1) × 100] of the ITO resistance value, that is, the resistance value between line ends was calculated, and is shown in Table 1 as “resistance value change”.
A resistance value change rate of 5% or more was judged as “× (poor)”, and less than 5% was judged as “good”.

[Discussion]
The pressure-sensitive adhesive compositions 1 and 4 obtained in Examples 1 and 4 had excellent adhesion characteristics and contained a phosphite compound, and thus were excellent in corrosion resistance reliability.
On the other hand, Comparative Example 1 was inferior in corrosion resistance reliability because it did not contain a phosphite compound.
In Comparative Example 2, since an excessive amount of the phosphite compound was added, the corrosion resistance reliability was impaired. Moreover, the optical reliability also tends to be slightly deteriorated by excessive addition of the phosphite compound.
In Comparative Example 3, a phosphate ester compound was added instead of the phosphite ester compound. In Comparative Example 3, the effect of suppressing the increase in resistance value of the ITO wiring as in the example was not obtained.
Comparative Example 4 is a pressure-sensitive adhesive composition that does not contain polar groups that cause electrode corrosion instead of adding a phosphite compound in order to ensure corrosion resistance reliability. Although the corrosion resistance reliability can be obtained by not having a polar group, the adhesive strength and the heat-and-moisture resistance cannot be obtained.
In Comparative Example 5, the polar group other than the acidic group was intended to achieve both corrosion resistance and wet heat whitening resistance, but the adhesion was inferior to that of the example.

From the said Example and the test result which this inventor performed so far, predetermined | prescribed (meth) acrylic-type copolymer, ie, (meth) acrylate or a vinyl monomer containing a carboxyl group, is 1.2 mass%-15 mass. % Of the (meth) acrylic copolymer contained in a proportion of 1 × 10 ⁻⁴ to 8 × 10 ⁻¹ parts by mass of the phosphite compound with respect to 100 parts by mass of the (meth) acrylic copolymer. It was found that oxidative deterioration can be prevented even if the pressure-sensitive adhesive composition contains an acid component.

In addition, it was also found that a more preferable effect can be obtained if the phosphite compound at this time is a phosphite compound represented by the following formula (1).
P [—OR] ₃ (wherein R is a hydrocarbon such as a substituted or unsubstituted aromatic, an alicyclic ring and an alkyl group. The plurality of R may be the same or different from each other) And a plurality of adjacent Rs may be bonded to each other to form a saturated or unsaturated ring structure.)

Claims (3)

A pressure-sensitive adhesive composition containing a (meth) acrylic copolymer having a mass average molecular weight of 100,000 to 1,500,000,
The (meth) acrylic copolymer is a copolymer having a composition containing 1.2% by mass to 15% by mass of a (meth) acrylate or vinyl monomer containing a carboxyl group,
ITO resistance value measured by the following method containing 1 × 10 ⁻⁴ to 8 × 10 ⁻¹ parts by mass of an aromatic phosphite compound with respect to 100 parts by mass of the (meth) acrylic copolymer. The rate of change [((Ω / Ω ₀ ) -1) × 100] of the conductive material is less than 5%.
(Measurement method of change rate of ITO resistance)
The pressure-sensitive adhesive composition for a conductive member is formed into a sheet having a thickness of 150 μm to form a pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive is applied to the ITO glass substrate for evaluation in which an ITO wiring made of indium oxide (ITO) is formed on the glass substrate. An ITO wiring with an adhesive sheet is created by laminating the sheets. Next, the resistance value (Ω ₀ ) of the ITO wiring at room temperature in the ITO wiring with the adhesive sheet is measured in advance, and the ITO wiring with the adhesive sheet is stored in a 65 ° C. 90% RH environment for 800 hours. The resistance value (Ω) after the storage of the ITO wiring in the ITO wiring with the adhesive sheet is measured, and the change rate [((Ω / Ω ₀ ) −1) × 100] of the ITO resistance value is calculated. The pressure-sensitive adhesive composition for a conductive member according to claim 1, wherein the conductive member of the pressure-sensitive adhesive composition for a conductive member is a transparent conductive film containing ITO (tin-doped indium oxide). The (meth) acrylic copolymer is a (meth) acrylate containing 30 to 90 parts by mass of a linear or branched alkyl (meth) acrylate having 4 to 18 carbon atoms in the side chain and a carboxyl group. Or it consists of a composition containing 1.2 mass parts or more and 15 mass parts or less of vinyl monomers, and 3 to 70 mass parts of (meth) acrylate or vinyl monomers having 1 to 3 carbon atoms in the side chain. It is a copolymer, The adhesive composition for electrically-conductive members of Claim 1 or 2 characterized by the above-mentioned.

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