TWI769960B - Adhesive sheet, laminated body for image display device configuration, and image display device - Google Patents

Abstract

The present invention relates to a photocurable adhesive sheet containing an ultraviolet absorber, and provides a novel adhesive sheet with UV-resistant foamability without hindering the photocurable performance. The present invention provides an adhesive sheet, which is characterized by having an adhesive layer formed by an adhesive composition containing an ultraviolet absorber and a photoinitiator, and the absorption coefficient of the ultraviolet absorber at a wavelength of 340 nm is 1×10 ³ mL/(g·cm) or more, and the absorption coefficient at a wavelength of 380 nm is less than 1×10 ³ mL/(g·cm), and the ratio is 0.1 to 1.6% by mass relative to the total mass of the above-mentioned adhesive composition Contains UV absorbers.

Description

Adhesive sheet, laminated body for image display device configuration, and image display device

The present invention relates to an adhesive sheet having an adhesive layer formed from an adhesive composition containing an ultraviolet absorber and a photoinitiator, and more particularly, to an adhesive sheet with UV-resistant foamability.

Image display devices used in computers, mobile devices (PDAs), game consoles, televisions (TVs), car navigation systems, touch panels, handwriting pads, etc., for example, use plasma displays (PDPs), liquid crystal displays (LCDs), In image display devices such as organic EL (Electroluminescence) displays (OLEDs), electrophoretic displays (EPDs), interferometric modulation displays (IMODs) and other flat or curved image display panels, in order to ensure visibility or In order to prevent breakage and the like, no voids are provided between the constituent members, and the constituent materials are bonded together with an adhesive sheet or a liquid adhesive for integration.

For example, in an image display device having a structure in which a touch panel is inserted between the viewing side of the liquid crystal module and the surface protection panel, a liquid adhesive or an adhesive sheet is disposed between the surface protection panel and the viewing side of the liquid crystal module , the touch panel and other components such as the touch panel and the liquid crystal module, the touch panel and the surface protection panel are bonded and integrated.

As a method of filling the voids between the constituent members of the image display device with such an adhesive, Patent Document 1 discloses a method of irradiating the voids with a liquid adhesive resin composition containing an ultraviolet curable resin after filling the voids with ultraviolet rays A method of light-hardening it.

Moreover, the method of filling the space|gap between the structural members for image display apparatuses using an adhesive sheet is also known. For example, Patent Document 2 discloses a method of irradiating the adhesive sheet with ultraviolet rays twice through the image display device constituting member after bonding the adhesive sheet crosslinked by ultraviolet rays once to the image display device constituting member. hardening method.

However, regarding the optical member used in an image display apparatus, there is a real concern about deterioration by ultraviolet rays, and in order to prevent this, there is a case where ultraviolet absorbance is required for the adhesive sheet. For example, as such an adhesive sheet, Patent Document 3 and Patent Document 4 propose a transparent adhesive sheet containing an ultraviolet absorber in an adhesive layer. prior art literature Patent Literature

Patent Document 1: International Publication No. 2010/027041 Patent Document 2: Japanese Patent No. 4971529 Patent Document 3: Japanese Patent No. 5945393 Patent Document 4: Japanese Patent Laid-Open No. 2015-229759

[Problems to be Solved by Invention]

In the case of imparting ultraviolet absorbance to the adhesive sheet, there are various purposes. For example, the purpose of preventing deterioration of the optical member adjacent to the pressure-sensitive adhesive sheet due to long-term exposure to ultraviolet rays can be cited. However, for this purpose, it is necessary not only to contain a relatively large amount of the ultraviolet absorber, but also to block light in a wide wavelength region with a wavelength of 380 nm or more. Therefore, when the photocurable pressure-sensitive adhesive sheet contains such an ultraviolet absorber, in order not to hinder the photocurability due to the action of the ultraviolet absorber, it is considered to utilize a reaction in a wider region of the ultraviolet to visible light region. Sexual Light Initiator. However, when such a photoinitiator is used, for example, when the photocurable adhesive sheet is stored under a fluorescent lamp, there arises a problem that photocuring proceeds slowly.

On the other hand, ultraviolet rays degrade not only optical members but also the adhesive sheet itself, and there is a possibility that foaming or peeling may occur due to decomposition products (outgassing) generated by the degradation of the adhesive sheet. Therefore, resistance to foaming in the adhesive sheet caused by exposure to ultraviolet rays (referred to as "ultraviolet foam resistance") is required.

In order for the adhesive sheet to have such UV-resistant foaming properties, it is necessary to make the adhesive sheet after photocuring have sufficient cohesive force to resist outgassing. However, when the photocurable adhesive sheet contains an ultraviolet absorber, if the content of the ultraviolet absorber is only increased in order to reduce the influence of ultraviolet rays, the ultraviolet absorber acts as a plasticizer and prevents the photocuring of the adhesive sheet. the possibility of sexuality, and therefore needs to be studied from a viewpoint completely different from this idea.

Therefore, the present invention relates to a photocurable adhesive sheet containing an ultraviolet absorber, and provides a novel adhesive sheet with UV foam resistance without hindering the photocurable performance. [Technical means to solve problems]

The present invention provides an adhesive sheet, which is characterized by having an adhesive layer formed by an adhesive composition containing an ultraviolet absorber and a photoinitiator, and the absorption coefficient of the ultraviolet absorber at a wavelength of 340 nm is 1×10 ³ mL/(g·cm) or more, and the absorption coefficient at a wavelength of 380 nm is less than 1×10 ³ mL/(g·cm), the above-mentioned adhesive composition relative to the total mass of the adhesive composition is 0.1～1.6 The ratio of mass % contains the above-mentioned ultraviolet absorber. [Effect of invention]

The adhesive sheet proposed by the present invention can obtain the desired effect by using an ultraviolet absorber having a specific absorption coefficient in a specific wavelength region and specifying the content ratio of the ultraviolet absorber. That is, since the ultraviolet absorber prevents the transmission of ultraviolet rays on the short wavelength side, even if the adhesive sheet is exposed to ultraviolet rays, outgassing from the adhesive sheet can be reduced. In this case, by specifying the content of the ultraviolet absorber, the ultraviolet absorber itself can be prevented from acting as a plasticizer to reduce the cohesive force of the adhesive sheet, and heat-resistant foaming at high temperatures can also be obtained.

Furthermore, as the above-mentioned photoinitiator, by using one whose absorption coefficient at a wavelength of 405 nm is less than 10 mL/(g·cm), the photoinitiator will not be activated in the visible light wavelength region, so even if it is a fluorescent lamp Storage under moderate visible light exposure also prevents photohardening. In addition, by specifying the content ratio of the ultraviolet absorber and the metal corrosion inhibitor, in particular, by using a specific metal corrosion inhibitor, the photohardenability by the photoinitiator is not hindered, and the metal corrosion resistance can also be obtained. .

Hereinafter, an example of an embodiment of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

＜This adhesive sheet＞ An adhesive sheet (hereinafter referred to as "the present adhesive sheet") as an example of the embodiment of the present invention is formed of an adhesive composition (hereinafter referred to as "the present adhesive composition") containing an ultraviolet absorber and a photoinitiator the adhesive layer.

Furthermore, the adhesive sheet only needs to have at least one or more of the above-mentioned adhesive layers, and may be composed of two or more multilayers, and in the case of multiple layers, a so-called base material layer or the like may be interposed. other layers. In this case, all the adhesive layers may be formed from the present adhesive composition, or at least the outermost layer may be formed from the present adhesive composition.

(The thickness of this adhesive sheet) The thickness of the adhesive sheet is preferably 10 μm or more and 500 μm or less. By reducing the thickness of the sheet, it is possible to respond to the requirement of thinning. On the other hand, if the thickness of the sheet is too thin, it may not be able to follow sufficiently, or it may not be able to exert itself, for example, when the surface to be adhered has irregularities. A condition of sufficient adhesion. Therefore, from this viewpoint, the thickness of the adhesive sheet is preferably 10 μm or more and 500 μm or less, more preferably 15 μm or more or 400 μm or less, and particularly preferably 20 μm or more or 350 μm or less.

<This adhesive composition> This adhesive composition contains an ultraviolet absorber and a photoinitiator. In addition to this, a (meth)acrylate (co)polymer, a crosslinking agent, a metal corrosion inhibitor, and other components may be included as necessary. In addition, the term "(co)polymer" includes homopolymers and copolymers, and the term "(meth)acrylate" includes acrylates and methacrylates.

(Ultraviolet absorber) The above ultraviolet absorber preferably has an absorption coefficient of 1×10 ³ mL/(g·cm) or more at a wavelength of 340 nm, and an absorption coefficient of less than 1×10 ³ mL/( at a wavelength of 380 nm. g・cm). By making the ultraviolet absorber have such a light-absorbing property, that is, it has the property that the wavelength region of the ultraviolet light absorbed is narrow, and further, it has the property of blocking only the ultraviolet light of relatively short wavelength, and it is possible to suppress the blocking of the adhesive sheet from passing light. Hardening of the initiator. In addition, even if the content of the ultraviolet absorber is reduced, it is possible to have ultraviolet foam resistance. From this viewpoint, the above-mentioned ultraviolet absorber is more preferably an absorption coefficient at a wavelength of 340 nm of 2 × 10 ³ mL/(g·cm) or more, and more preferably 3 × 10 ³ mL/(g·cm) above, especially 3.5×10 ³ mL/(g·cm) or above. Moreover, the above-mentioned ultraviolet absorber is more preferably less than 8 × 10 ² mL/(g·cm), wherein the absorption coefficient under the wavelength of 380 nm is less than 7 × 10 ² mL/(g·cm), especially is less than 6×10 ² mL/(g·cm).

More preferably, the above-mentioned ultraviolet absorber has an absorption coefficient of less than 1×10 ² mL/(g·cm) at a wavelength of 405 nm. By making the absorption coefficient of the ultraviolet absorber in wavelength 405 nm into this range, the hue of this adhesive sheet, specifically, can suppress the yellow tone. Moreover, the hue change can also be suppressed. From this viewpoint, the above-mentioned ultraviolet absorber preferably has an absorption coefficient of less than 1 × 10 ² mL/(g·cm) at a wavelength of 405 nm, and more preferably less than 8 × 10 ¹ mL/(g·cm). cm), especially less than 5×10 ¹ mL/(g·cm).

The above-mentioned ultraviolet absorber further preferably has a melting point of 100°C or lower. When the melting point of the above-mentioned ultraviolet absorber is 100° C. or lower, the dispersibility at the time of mixing in the adhesive composition is excellent, and uniform mixing is easy. Therefore, it is more preferable that the said ultraviolet absorber has a melting point of 100°C or less, and more preferably -50°C or more or 50°C or less.

Examples of the above-mentioned ultraviolet absorber include those having a structure selected from the group consisting of a benzotriazole structure, a benzophenone structure, a trisulfan structure, a benzoate structure, an oxaniline structure, a salicylate structure, and a cyanoacrylate. As for one type or two or more types of structures in the group consisting of structures, those having a specific absorption coefficient may be selected from among them. Among them, those having a benzophenone structure are preferably selected from the viewpoints of adjustment of the above-mentioned absorption coefficient, compatibility with adhesives, and stability when added together with other various additives.

Furthermore, the absorption coefficient at the measurement wavelength of 340 nm can be measured, for example, by adding a solution diluted with a solvent (acetonitrile, acetone) that does not absorb light of the measurement wavelength into a quartz cell, and measuring its absorbance. The absorption coefficient can be obtained by the following formula. α340=A340×d/c α340: Absorption coefficient at wavelength 340 nm [mL/(g・cm)] A340: Absorbance at wavelength 340 nm c: solution concentration [g/mL] d: (of quartz pool) optical path length [cm]

In addition, when calculating the absorbance coefficient, the absorbance converted from the measurement result of the transmittance can also be used. A340=-Log(T340/100) T340: Transmittance at wavelength 340 nm [%]

The absorption coefficient at a wavelength of 380 nm or 405 nm can also be obtained by the same method as above.

It is preferable that the said adhesive composition contains the said ultraviolet absorber in the ratio of 0.1-1.6 mass % with respect to the total mass of this adhesive composition. By containing the ultraviolet absorber in this ratio, there is no possibility of hindering curing when the adhesive sheet is photocured, and the ultraviolet absorber does not plasticize the adhesive more than necessary to impart sufficient cohesive force to the adhesive sheet. The adhesive sheet can have excellent UV foam resistance. From this viewpoint, the ultraviolet absorber is preferably contained in a ratio of 0.1 to 1.6 mass % with respect to the total mass (100 mass %) of the adhesive composition, and more preferably 0.2 mass % or more or 1.4 mass %. Mass % or less, especially 0.3 mass % or more or 1.0 mass % or less, and more especially 0.4 mass % or more or 0.9 mass % or less are contained in the ratio. In view of the above, the ultraviolet absorber is preferably contained in a ratio of 0.1 to 1.4 mass %, 0.1 to 1.0 mass %, or 0.1 to 0.9 mass % with respect to the total mass (100 mass %) of the adhesive composition, more preferably It is contained in a ratio of 0.2 to 1.6 mass %, 0.2 to 1.4 mass %, 0.2 to 1.0 mass %, or 0.2 to 0.9 mass %, more preferably 0.3 to 1.6 mass %, 0.3 to 1.4 mass %, 0.3 to 1.0 mass % % or a ratio of 0.3 to 0.9 mass %, preferably 0.4 to 1.6 mass %, 0.4 to 1.4 mass %, 0.4 to 1.0 mass %, or 0.4 to 0.9 mass %.

From the same viewpoint, in the present adhesive composition, the ultraviolet absorber is preferably contained in a ratio of 30 to 100 parts by mass with respect to 100 parts by mass of the photoinitiator, more preferably 40 parts by mass or more and Or 95 mass parts or less, especially 50 mass parts or more or 90 mass parts or less are contained in the ratio.

(photoinitiator) As the photoinitiator, a photoinitiator whose absorption coefficient at a wavelength of 405 nm is less than 10 mL/(g·cm) is particularly preferred. Since the photoinitiator having such an absorption coefficient has low activity in the visible light region, it is possible to obtain an adhesive sheet having a low possibility of photocuring and excellent storage stability even when stored under a fluorescent lamp. From this viewpoint, it is more preferable to use a photoinitiator whose absorption coefficient at a wavelength of 405 nm is less than 8 mL/(g·cm), and it is particularly preferable to use a photoinitiator whose absorption coefficient at a wavelength of 405 nm is 5 mL/(g).・cm) or less photoinitiator.

Photoinitiators are roughly classified into two categories according to the mechanism of free radical generation, and are roughly divided into cleavage-type photoinitiators that can generate free radicals by cleavage of the single bond of the photoinitiator itself, and photoinitiators that are excited by light. Formation of excited complexes with hydrogen donors in the system enables hydrogen abstraction type initiators for hydrogen transfer of hydrogen donors. Among them, the photoinitiator contained in the adhesive composition is preferably a hydrogen abstraction type initiator. The hydrogen abstraction type is more likely to obtain cohesion after photocuring, and is excellent in durability such as heat-resistant foaming properties. In addition, unlike the cracking type, there is no possibility that the decomposition product will adversely affect corrosion, so it is not only easy to balance with metal corrosion resistance, but also can be photocured to a state in which photocurability remains.

Among these, the cleavage-type photoinitiator includes, for example, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2- Hydroxy-2-methyl-1-phenyl-propan-1-one, 1-(4-(2-hydroxyethoxy)phenyl)-2-hydroxy-2-methyl-1-propane-1- ketone, 2-hydroxy-1-[4-{4-(2-hydroxy-2-methyl-propionyl)benzyl}phenyl]-2-methyl-propan-1-one, oligo(2 -Hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)acetone), methyl phenylglyoxylate, 2-benzyl-2-dimethylamino-1- (4-Morpholinylphenyl)butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-(bis Methylamino)-2-[(4-methylphenyl)methyl)-1-[4-(4-morpholinyl)phenyl]-1-butanone, bis(2,4,6- Trimethylbenzyl)-phenylphosphine oxide, 2,4,6-trimethylbenzyldiphenylphosphine oxide, (2,4,6-trimethylbenzyl)ethoxy phenylphosphine oxide, or derivatives thereof, etc. Among these, bis(2,4,6-trimethylbenzyl)-phenylphosphine oxide and 2,4,6-trimethylbenzyldiphenylphosphine oxide are particularly preferred.

Moreover, as a hydrogen abstraction type photoinitiator, benzophenone, Michler's ketone, 2-ethylanthraquinone, thioxanthone, its derivative(s), etc. are mentioned, for example.

Among the above-mentioned photoinitiators, in terms of easier to obtain cohesive force after photohardening than cracked photoinitiators, the absorption coefficient at a wavelength of 405 nm is less than 10 mL/(g·cm). Hydrogen light initiator.

<(Meth)acrylate (co)polymer> The present adhesive composition may comprise (meth)acrylate (co)polymers.

As the (meth)acrylate (co)polymer, for example, in addition to a homopolymer of an alkyl (meth)acrylate, a copolymer obtained by polymerizing with a monomer component having copolymerizability therewith can also be mentioned. thing.

More preferable (meth)acrylate (co)polymers include alkyl (meth)acrylates and copolymerizable ones selected from the group consisting of hydroxyl group-containing monomers, amine group-containing monomers, epoxy group-containing monomers A copolymer in which any one or more of monomers, amide group-containing monomers and other vinyl monomers are used as structural units. In particular, if a highly polar component such as a carboxyl group is used as a copolymerization component, the adherend is especially a conductive member such as an ITO (Indium Tin Oxides, indium tin oxide) film or an IGZO (Indium Gallium Zinc Oxide, indium gallium zinc oxide) film and the like. Oxidative deterioration is caused by the oxidative action, so in order to suppress corrosion of the metal member, a (meth)acrylate (co)polymer which does not contain a carboxyl group-containing monomer as a structural unit is preferable. Moreover, it is preferable that the adhesive layer formed from the present adhesive composition containing such a (meth)acrylate (co)polymer is photocured by light irradiation. In addition, "does not contain a carboxyl group-containing monomer as a structural unit" means "does not contain substantially", that is, means "does not contain intentionally". However, there are cases where it is unavoidably contained, so not only the case of not containing it at all, but also the (meth)acrylate (co)polymer contained in the (meth)acrylate (co)polymer in less than 0.5 mass %, preferably less than 0.1 mass %. The case of sexual monomer A.

The (meth)acrylate (co)polymer can be produced by a conventional method by using a polymerization initiator as necessary, such as monomers exemplified below.

As an example of a more specific (meth)acrylate (co)polymer, a linear or branched alkyl (meth)acrylate (hereinafter also referred to as "copolymerization") having a carbon number of 4 to 18 in a side chain can be mentioned. A copolymer of monomer components selected from any one or more selected from the group consisting of the following B to E which can be copolymerized therewith.

・Macromonomer (hereinafter also referred to as "co-monomer B") ・(Meth)acrylate having 1 to 3 carbon atoms in the side chain (hereinafter also referred to as "co-monomer C") ・Hydroxy-containing monomer (hereinafter also referred to as "co-monomer D") ・Other vinyl monomers (hereinafter also referred to as "co-monomer E")

Among them, as an example of the (meth)acrylate (co)polymer, a copolymer containing a monomer component containing (a) a comonomer A and a comonomer B, or a copolymer containing a (b) copolymer can be mentioned. A preferred example is a copolymer of the monomer components of the comonomer A, the comonomer C, the comonomer D and/or the comonomer E.

(Comonomer A) Examples of linear or branched alkyl (meth)acrylates (co-monomer A) having 4 to 18 carbon atoms in the side chain include n-butyl (meth)acrylate and isobutyl (meth)acrylate. Butyl, second butyl (meth)acrylate, 3rd butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, neopentyl (meth)acrylate, ( Hexyl (meth)acrylate, cyclohexyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, (meth)acrylic acid Isooctyl, nonyl (meth)acrylate, isononyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate , Undecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, cetyl (meth)acrylate , stearyl (meth)acrylate, isostearyl (meth)acrylate, behenyl (meth)acrylate, iso(meth)acrylate, 3,5,5-(meth)acrylate Trimethylcyclohexyl, dicyclopentyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, benzyl (meth)acrylate, etc. . These can be used alone or in combination of two or more.

The above-mentioned copolymerizable monomer A is preferably contained in the total monomer component of the copolymer in an amount of 30% by mass or more and 90% by mass or less, more preferably 35% by mass or more or 88% by mass or less, and especially It is contained in the range of 40 mass % or more or 85 mass % or less.

(Comonomer B) The above-mentioned macromonomer (co-monomer B) is a monomer having a carbon number of a side chain of 20 or more when it is polymerized into a (meth)acrylate (co)polymer. By using the comonomer B, the (meth)acrylate (co)polymer can be made into a graft copolymer. Therefore, the characteristics of the main chain and the side chain of the graft copolymer can be changed by the selection or compounding ratio of the copolymerizable monomer B and other monomers.

As the aforementioned macromonomer (co-monomer B), it is preferable that the skeleton component contains an acrylate copolymer or a vinyl-based polymer. Examples of the skeleton component of the macromonomer include those exemplified by the above-mentioned comonomer A, the comonomer C described below, and the comonomer D described below, and these can be used alone or in combination. Use in combination of 2 or more.

The macromonomer is one having a radically polymerizable group or a functional group such as a hydroxyl group, an isocyanate group, an epoxy group, a carboxyl group, an amine group, an amide group, and a thiol group. The macromonomer is preferably one having a radically polymerizable group that can be copolymerized with other monomers. One or two or more radically polymerizable groups may be contained, and one of them is particularly preferred. When the macromonomer has a functional group, the functional group may also contain one or two or more, and one of the functional groups is particularly preferred. Moreover, about a radical polymerizable group and a functional group, either one may be contained, and both may be contained.

The number average molecular weight of the comonomer B is preferably 500 to 20,000, and among them, 800 or more or 8,000 or less, especially 1,000 or more or 7,000 or less is preferable. As the megamonomer, a commonly produced one (eg, a megamonomer manufactured by Toa Gosei Corporation, etc.) can be appropriately used. The above-mentioned copolymerizable monomer B is preferably 5 mass % or more and 30 mass % or less, 6 mass % or more or 25 mass % or less, especially 8 mass % or more in the total monomer component of the copolymer. It is contained within the range of 20 mass % or less.

Examples of the (meth)acrylate (co)polymer containing the comonomer B include (meth)acrylate copolymer (a-1) containing a graft copolymer having a macromonomer as a branch component. .

When such a (meth)acrylate copolymer (a-1) is used to form an adhesive layer, the adhesive layer can maintain a sheet-like form at room temperature and exhibit self-adhesiveness, and when heated, melt or flow The hot-melt property can further be light-hardened, and after light-hardening, it can exert excellent cohesive force for bonding. Therefore, if the above-mentioned (meth)acrylate copolymer (a-1) is used, even if it is in an uncrosslinked state, it exhibits tackiness at room temperature (20°C), and if it is heated to 50 to 100°C, the Preferably, the temperature is 60°C or higher or 90°C or lower, so that it can have softening or fluidizing properties.

Since the glass transition temperature of the copolymer component constituting the main component of the (meth)acrylate copolymer (a-1) will affect the flexibility of the adhesive layer at room temperature, or the adhesion of the adhesive layer to the adherend The wettability, that is, the adhesiveness, has an influence. Therefore, in order to obtain the appropriate adhesiveness (tackiness) of the adhesive sheet 1 at room temperature, the glass transition temperature is preferably -70°C to 0°C, and particularly preferably -65°C or higher or -5°C or lower, especially -60°C or higher or -10°C or lower. However, even if the glass transition temperature of the copolymer component is the same temperature, the viscoelasticity can be adjusted by adjusting the molecular weight. For example, it can be made softer by reducing the molecular weight of the copolymer component.

(Comonomer C) Examples of the (meth)acrylate (co-monomer C) having 1 to 3 carbon atoms in the side chain include methyl (meth)acrylate, ethyl (meth)acrylate, and (meth)acrylic acid. n-propyl ester, isopropyl (meth)acrylate, etc. These can be combined 1 type or 2 or more types.

The above-mentioned copolymerizable monomer C is preferably contained in the total monomer component of the copolymer in an amount of 0 mass % or more and 70 mass % or less, more preferably 3 mass % or more or 65 mass % or less, and especially It is contained in the range of 5 mass % or more or 60 mass % or less.

(Comonomer D) Examples of the hydroxyl group-containing monomer (co-monomer D) include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, hydroxypropyl 3-(meth)acrylate, Hydroxyalkyl (meth)acrylates such as 2-hydroxybutyl (meth)acrylate. These can be combined 1 type or 2 or more types.

The above-mentioned copolymerizable monomer D is preferably contained in the total monomer component of the copolymer in an amount of 0 mass % or more and 30 mass % or less, more preferably 0 mass % or more or 25 mass % or less, and especially It is contained in the range of 0 mass % or more or 20 mass % or less.

(Comonomer E) As said other vinyl monomer (copolymerizable monomer E), the compound which has a vinyl group in a molecule|numerator other than the copolymerizable monomer A-D is mentioned. Examples of such compounds include functional monomers having functional groups such as amide groups and alkoxyalkyl groups in the molecule, polyalkylene glycol di(meth)acrylates, vinyl acetate, propylene Vinyl ester monomers such as vinyl acetate and vinyl laurate, and aromatic vinyl monomers such as styrene, chlorostyrene, chloromethylstyrene, α-methylstyrene and other substituted styrenes. These can be combined 1 type or 2 or more types.

The above-mentioned copolymerizable monomer E is preferably contained in the total monomer component of the copolymer in an amount of 0 mass % or more and 30 mass % or less, more preferably 0 mass % or more or 25 mass % or less, and especially It is contained in the range of 0 mass % or more or 20 mass % or less.

In addition to those disclosed above, epoxy-containing groups such as glycidyl (meth)acrylate, glycidyl α-ethylacrylate, and 3,4-epoxybutyl (meth)acrylate can also be appropriately used as required. Monomers; (meth)acrylic acid dimethylaminoethyl ester, (meth)acrylic acid diethylaminoethyl ester and other amino group-containing (meth)acrylate monomers; (meth)acrylamide, N- Tertiary butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (methyl) ) monomers containing amide group or amide group, such as acrylamide, diacetone (meth) acrylamide, maleic acid amide, maleimide, etc.; vinylpyrrolidone, Heterocyclic basic monomers such as vinylpyridine and vinylcarbazole, etc.

Among the above, as a preferable example of the (meth)acrylate (co)polymer, for example, a polymer selected from the group consisting of 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, (methyl) base) decyl acrylate, isostearyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, butyl (meth)acrylate, ethyl (meth)acrylate , any one or more monomer components (a) from the group consisting of methyl (meth)acrylate, and selected from the group consisting of hydroxyethyl (meth)acrylate and hydroxy (meth)acrylate having organic functional groups, etc. Propyl ester, hydroxybutyl (meth)acrylate, glycerol (meth)acrylate, glycidyl (meth)acrylate, (meth)acrylamide, (meth)acrylonitrile, fluorinated (meth) A (meth)acrylate copolymer obtained by copolymerizing any one or more monomer components of the monomer component (b) in the group consisting of acrylate and polysiloxane (meth)acrylate. In addition, as an example of a preferable (meth)acrylate (co)polymer, a chemical bond formed by the combination of any functional group of a hydroxyl group and an isocyanate group or an amine group and an isocyanate group can be cited, or one with a macromolecule A graft copolymer in which the monomer acts as a branch component.

The mass average molecular weight of the (meth)acrylate (co)polymer is 100,000 or more and 1.5 million or less, among them, 150,000 or more or 1.3 million or less, and particularly preferably 200,000 or more or 1.2 million or less. In the case of obtaining an adhesive composition with a higher cohesive force, the mass average molecular weight of the (meth)acrylate (co)polymer is from the viewpoint that the larger the molecular weight, the more cohesive force is obtained by the cross-linking of the molecular chain. It is preferably 700,000 or more and 1.5 million or less, especially 800,000 or more or 1.3 million or less. On the other hand, in the case of obtaining an adhesive composition with high fluidity or stress relaxation, the mass average molecular weight is preferably 100,000 or more and 700,000 or less, especially 150,000 or more or 600,000 or less. On the other hand, when a solvent is not used when forming an adhesive sheet or the like, it is difficult to use a polymer having a relatively large molecular weight. Therefore, the mass average molecular weight of the (meth)acrylate (co)polymer is 100,000 or more and 700,000 or less, especially 150,000 or more or 600,000 or less, especially 200,000 or more or 500,000 or less, and more preferably.

(crosslinking agent) The present adhesive composition may optionally contain a crosslinking agent. By adding a crosslinking agent, the degree of crosslinking can be increased, in other words, the gel fraction can be increased, and the cohesive force can be increased. For example, as a method of crosslinking the above-mentioned (meth)acrylate (co)polymer, the addition of a reactive group such as a hydroxyl group or a carboxyl group which can be introduced into the (meth)acrylate (co)polymer can be mentioned. A method of chemically bonding a crosslinking agent and reacting it by heating or curing, or adding a polyfunctional (meth)acrylate having two or more (meth)acryloyl groups as a crosslinking agent, and a photoinitiator A method in which a reaction initiator is used and the crosslinking is carried out by ultraviolet irradiation or the like. Among them, from the viewpoint of not depleting the polar functional groups in the adhesive composition due to the reaction, and being able to maintain high cohesive force or adhesive physical properties derived from the polar components, it is preferable to irradiate with light such as ultraviolet rays. connection method.

Examples of the above-mentioned crosslinking agent include a group selected from the group consisting of a (meth)acryloyl group, an epoxy group, an isocyanate group, a carboxyl group, a hydroxyl group, a carbodiimide group, an oxazoline group, an aziridine group, and a vinyl group. , amine group, imino group, amide group, N-substituted (meth)acrylamido group, alkoxysilyl group at least one kind of crosslinking functional group crosslinking agent, you can use one kind or combine Use in combination of 2 or more. Furthermore, the crosslinkable functional group may be protected by a protecting group capable of deprotection.

Among them, polyfunctional (meth)acrylates are preferred from the viewpoint of the ease of controlling the crosslinking reaction. Examples of such polyfunctional (meth)acrylates include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol Alcohol di(meth)acrylate, polyalkylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, glycerol di(meth)acrylate, neotaerythritol tri(meth)acrylate Meth)acrylate, Neotaerythritol tetra(meth)acrylate, Dipivalerythritol hexa(meth)acrylate, Tripentaerythritol penta(meth)acrylate, Trimethylolpropane tri(methyl)acrylate ) acrylates, tris(acryloyloxyethyl)isocyanurate and other UV-curable polyfunctional monomers, polyester (meth)acrylates, epoxy (meth)acrylates , polyfunctional acrylate oligomers such as urethane (meth)acrylate and polyether (meth)acrylate, or polyfunctional acrylamide, etc.

Moreover, as a crosslinking agent which has two or more types of crosslinkable functional groups, for example, glycidyl (meth)acrylate, glycidyl α-ethylacrylate, and (meth)acrylic acid-3,4-ring are exemplified. Epoxy-containing monomers such as oxybutyl ester, 4-hydroxybutyl (meth)acrylate glycidyl ether, etc.; (meth)acrylate 2-isocyanatoethyl ester, isocyanate 2-(2-(methyl) Acryloyloxyethyloxy)ethyl ester, 2-(0-[1'-methylpropylideneamino]carboxyamino)ethyl (meth)acrylate, 2-[(3,5-diethyl) Methylpyrazolyl)carbonylamino](meth)ethyl acrylate and other monomers containing isocyanate groups or blocked isocyanate groups; vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxy propylpropyltrimethoxysilane, 3-(meth)acryloyloxypropylmethyldiethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, N-2- Various silane coupling agents such as (aminoethyl)-3-aminopropylmethyldimethoxysilane and 3-isocyanatopropyltriethoxysilane.

The crosslinking agent having two or more types of crosslinkable functional groups may take a structure in which a functional group reacts with the (meth)acrylate (co)polymer to bond with the (meth)acrylate (co)polymer . By adopting such a structure, for example, a double-bonded crosslinkable functional group such as a (meth)acryloyl group or a vinyl group can be chemically bonded to the (meth)acrylate (co)polymer. Moreover, by making a crosslinking agent couple|bond with a (meth)acrylate (co)polymer, there exists a tendency which can suppress the bleed-out of a crosslinking agent, or the unintended plasticization of this adhesive sheet. Moreover, since the reaction efficiency of a photocrosslinking reaction can be accelerated|stimulated by making a crosslinking agent and a (meth)acrylate (co)polymer couple|bond, there exists a tendency for the hardened|cured material with higher cohesion to be obtained.

The present adhesive composition may further contain a monofunctional monomer that reacts with the crosslinkable functional group of the crosslinking agent. Examples of such monofunctional monomers include alkyl (meth)acrylates such as methyl acrylate; hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate. , Polyalkylene glycol (meth)acrylate and other hydroxyl-containing (meth)acrylates; (meth)acrylate tetrahydrofurfuryl, methoxypolyethylene glycol (meth)acrylate and other ether group-containing (Meth)acrylate; (meth)acrylamide, dimethyl (meth)acrylamide, diethyl (meth)acrylamide, (meth)acrylamide, isopropyl (meth)acrylamide Meth) acrylamide, dimethylaminopropyl (meth) acrylamide, phenyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butyl (meth)acrylamide-based monomers such as oxymethyl (meth)acrylamide and the like. In particular, it is preferable to use a hydroxyl group-containing (meth)acrylate or a (meth)acrylamide-based monomer from the viewpoint of improving the adhesion to an adherend or the effect of suppressing wet-heat whitening.

The content of the crosslinking agent is preferably 0.01 or more with respect to 100 parts by mass of the above-mentioned (meth)acrylate (co)polymer from the viewpoint of balancing the flexibility and cohesive force of the adhesive composition. The ratio of 10 parts by mass or less is blended, and among them, it is preferably 0.05 parts by mass or more or 8 parts by mass or less, especially 0.1 parts by mass or more or 5 parts by mass or less.

Furthermore, when the present adhesive sheet is a multilayer, the content of the crosslinking agent in the layers constituting the adhesive sheet, regarding the intermediate layer or the layer that becomes the base material, may exceed the above-mentioned range. The content of the crosslinking agent in the intermediate layer or the layer to be the base material is preferably adjusted at a ratio of 0.01 to 40 parts by mass relative to 100 parts by mass of the (meth)acrylate (co)polymer, and particularly preferred It is 1 mass part or more or 30 mass parts or less, especially 2 mass parts or more or 25 mass parts or less.

(other ingredients) In addition to the above-mentioned (meth)acrylate (co)polymer, an ultraviolet absorber, a photoinitiator, and a crosslinking agent, this adhesive composition may contain other components as needed. Examples of other components include light stabilizers, metal inerts, metal corrosion inhibitors, antiaging agents, antistatic agents, moisture absorbing agents, foaming agents, defoaming agents, inorganic particles, viscosity modifiers, and adhesion imparting resins. , various additives such as photosensitizers, fluorescent agents, reaction catalysts (tertiary amine compounds, quaternary ammonium compounds, tin laurate compounds, etc.), etc. In addition to this, well-known components which are compounded in a normal adhesive composition can also be contained suitably. Moreover, each component may be used in combination of 2 or more types.

Among the above, it is particularly preferable to contain a light stabilizer. By using a light stabilizer in combination with the above-mentioned ultraviolet absorber, the ultraviolet ray resistance foaming property can be further improved. Among the above-mentioned light stabilizers, hindered amine compounds (HALS) are particularly preferred.

(Manufacturing method of this adhesive composition) The present adhesive composition can be obtained by mixing a photoinitiator, an ultraviolet absorber, and other components in specific amounts, respectively.

The mixing method at this time is not particularly limited, and the mixing order of each component is also not particularly limited. The apparatus for mixing is also not particularly limited, and for example, a universal kneader, a planetary mixer, a Banbury mixer, a kneader, a frame mixer, a pressure kneader, a three-roll mill, and a two-roll mill can be used. A solvent can also be used for mixing if desired. Moreover, this adhesive composition can be used as a solvent-free system which does not contain a solvent. By using it as a solvent-free system, it has the advantages of no residual solvent and improved heat resistance and light resistance.

In addition, a heat treatment step may be added when the present adhesive composition is produced, and in this case, it is preferable to perform heat treatment after mixing each component of the present adhesive composition in advance. It is also possible to use a master batch by concentrating various mixed components.

<Adhesive layer> The adhesive sheet has an adhesive layer formed from the adhesive composition, and the adhesive layer may be cured completely, or may be in a state with room for curing or an uncured state. Among these, it is preferable that the adhesive layer has a property of being photohardened by light irradiation. In addition, the adhesive layer preferably contains a UV absorber and a photoinitiator, and a (meth)acrylate (co) without a carboxyl group-containing monomer in the (meth)acrylate (co)polymer described above. polymer as the present adhesive composition. In this way, the present adhesive sheet can be favorably used for bonding of constituent members for image display devices including various conductive members, such as a conductive member having a conductive pattern formed of a metal material.

<This photocurable adhesive sheet> Among the present adhesive sheets, which has the property of being photocured by light irradiation, that is, a photocurable adhesive sheet (hereinafter referred to as "this photocurable adhesive sheet") can be subjected to light irradiation after being attached to a member to be adhered. Light hardening. If it is such a photocurable adhesive sheet, it is possible to simultaneously realize the level difference absorption when it is attached to the adherend member and the foaming resistance reliability after the adherend member.

As the photocurable adhesive sheet, it is preferable to have the present adhesive composition containing an ultraviolet absorber, a photoinitiator, and a (meth)acrylate (co)polymer that does not contain a carboxyl group-containing monomer. The above-mentioned UV absorber has an absorption coefficient of 1×10 ³ mL/(g・cm) or more at a wavelength of 340 nm, and an absorption coefficient of less than 1×10 ³ mL/(g・cm) at a wavelength of 380 nm. cm), the above-mentioned adhesive composition contains an ultraviolet absorber in a ratio of 30-100 parts by mass relative to 100 parts by mass of the photoinitiator, and the adhesive layer has the property of being photohardened by light irradiation.

The photocurable adhesive sheet may be cured (also referred to as "pre-curing") to a state that leaves room for photo-curing, or may be completely unpre-cured. In this case, the gel fraction of the photocurable adhesive sheet without pre-curing is preferably 5% or less. On the other hand, the gel fraction of the pre-cured photocurable adhesive sheet is preferably 80% or less, more preferably 5% or more or 70% or less, especially 10% or more or 60% or less. The gel fraction after the photocurable adhesive sheet is finally photocured (referred to as "photocuring" or "formal curing") is preferably 30% or more, especially 40% or more, especially 50% or more. By photo-curing the photo-curable adhesive sheet in such a range, even if the photo-curable adhesive sheet is placed in a severe high temperature and high humidity environment, the cohesive force becomes high, and the foaming resistance reliability can be improved.

As a preferable formation method of the adhesive bond layer with which this photocurable adhesive sheet is equipped, the following (1) or (2) are mentioned.

(1) In the production of the photocurable adhesive sheet, an adhesive layer in a state in which the shape of the sheet is maintained in a pre-cured (primary cross-linking) state and has photocurability (photoactivity) is formed. (2) In the production of the photocurable adhesive sheet, an adhesive layer is formed that maintains the shape of the sheet in an uncured (crosslinked) state and has a photohardening (photoactive) state.

As a specific example of the above-mentioned (1), for example, the following method is mentioned. The compound of the reacted functional group (ii) and, if necessary, the composition (adhesive) of a polyfunctional (meth)acrylate having two or more (meth)acryloyl groups are heated or cured to form an adhesive agent layer. According to this method, the functional group (i) in the (meth)acrylate (co)polymer reacts with the functional group (ii) in the compound to form a chemical bond, thereby hardening (crosslinking) to form an adhesive layer . By forming the adhesive layer in this way, the photopolymerization initiator can be kept active and present in the adhesive layer. In addition, in this case, as the photopolymerization initiator, any one of the above-mentioned cleavage type photoinitiator and hydrogen abstraction type photoinitiator can be used.

As the combination of the functional group (i) and the functional group (ii), for example, a carboxyl group and an epoxy group, a carboxyl group and an aziridine group, a carboxyl group and an isocyanate group, a hydroxyl group and an isocyanate group, or an amino group and an isocyanate group are preferred. Among these, a combination of a hydroxyl group (functional group (i)) and an isocyanate group (functional group (ii)) or an amine group (functional group (i)) and an isocyanate group (functional group (ii)) is particularly preferred. More specifically, the case where the above-mentioned (meth)acrylate copolymer has a hydroxyl group is a particularly preferable example, and for example, ( Meth)acrylate copolymer, and the above-mentioned compound has an isocyanate group.

Moreover, the compound which has the said functional group (ii) may further have radically polymerizable functional groups, such as a (meth)acryloyl group. Thereby, the photohardening (crosslinking) property of the (meth)acrylate (co)polymer obtained by this radically polymerizable functional group can be maintained, and an adhesive layer can be formed. More specifically, the case where the above-mentioned (meth)acrylate (co)polymer has a hydroxyl group is a particularly preferable example, and for example, (meth)acrylic acid as a copolymer containing the monomer component of the above-mentioned hydroxyl group-containing monomer is used. ester copolymer, and the above-mentioned compound has a (meth)acryloyl group, for example, the above-mentioned compound is 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate or isocyanate 1 , 1-(bisacryloyloxymethyl) ethyl ester, etc. In this way, by utilizing the cross-linking reaction between (meth)acrylate (co)polymers caused by the radically polymerizable functional groups, it is possible to avoid using polyfunctional polyfunctional groups having two or more (meth)acryloyl groups. (Meth)acrylate also has the advantages that the cohesion force after photocuring (crosslinking) is easily improved efficiently, and the reliability is excellent, so it is more preferable.

As another specific example of said (1), the method of using the said hydrogen abstraction type initiator as a photopolymerization initiator is mentioned, for example. The hydrogen abstraction type initiator can be reused as a photopolymerization initiator because it returns to the base state even if it is excited once. In this way, by using the hydrogen abstraction type photoinitiator, the photohardening (crosslinking) property obtained by the photopolymerization initiator can be maintained even after the production of the adhesive sheet.

As a specific example of said (2), the method of using the said macromonomer as a monomer component which comprises a (meth)acrylate copolymer is mentioned, for example. More specifically, a method of utilizing a graft copolymer having a macromonomer as a branch component can be mentioned. By using such a macromonomer, it is possible to maintain a state in which the branch components are attracted to each other and physically cross-linked in the form of a composition (adhesive) at room temperature. Therefore, the sheet state can be maintained without being cured (crosslinked), and an adhesive sheet having an adhesive layer containing a photoinitiator that generates radicals when light is received can be produced. In addition, in this case, as the photopolymerization initiator, any one of the above-mentioned cleavage type photoinitiator and hydrogen abstraction type photoinitiator can be used.

The photocurable adhesive sheet preferably has the following spectroscopic properties. That is, the light transmittance at a wavelength of 320 nm of the present photocurable adhesive sheet is preferably 10% or less, preferably 5% or less, and particularly preferably 3% or less. The light transmittance at a wavelength of 340 nm is preferably 20% or less, preferably 10% or less, and more preferably 5% or less. By having the said light transmittance, generation|occurrence|production of foaming, peeling, etc. accompanying the deterioration of an adhesive sheet itself can be suppressed.

The light transmittance of the photocurable adhesive sheet at a wavelength of 365 nm is preferably 10% or more, preferably 15% or more or 90% or less, especially more preferably 20% or more and 80% or less. The light transmittance of the photocurable adhesive sheet at a wavelength of 380 nm is preferably more than 20%, preferably more than 30% or less than 95%, especially more preferably more than 40% and less than 90%. The light transmittance of the photocurable adhesive sheet at a wavelength of 395 nm is preferably 50% or more, preferably 70% or more, especially more preferably 80% or more. By having the above-mentioned light transmittance, the photoinitiator is easily activated, so that the cohesive force of the adhesive after photocuring can be sufficiently obtained, and the reliability can be easily obtained.

The preferred embodiment of the photo-curable adhesive sheet is the same as the above-mentioned adhesive sheet, and these can be appropriately selected and applied. Moreover, the preferred embodiment of the present adhesive sheet and the preferred embodiment of the photo-curable adhesive sheet can be mutually replacement.

(metal corrosion inhibitor) However, when the present photocurable adhesive sheet is formed from the present adhesive composition mainly composed of a (co)polymer containing no monomer component containing a carboxyl group, the corrosion resistance to metal good. However, studies have been conducted on the corrosion of the metal material when the photo-hardening adhesive sheet is attached to a conductive member formed of a metallic material containing a specific metal such as silver and photo-hardened, and as a result, the light contained in the adhesive sheet has been studied. The initiator is activated by light to generate free radicals, and since the free radicals react with silver in the metal material, it is known that there is a possibility of corrosion of the metal material containing silver. In order to solve this problem, it is proposed to form a protective film on the silver of the conductive member by including a metal corrosion inhibitor in the photocurable adhesive sheet, thereby suppressing the above-mentioned free radicals generated from the photoinitiator due to light irradiation and The silver of the conductive member reacts. From the above viewpoints, it is preferable that the present photocurable adhesive sheet has an adhesive layer formed from the present adhesive composition containing a metal corrosion inhibitor.

In the present adhesive composition, the metal corrosion inhibitor is preferably contained in a ratio of 0.05 to 2.0 mass % with respect to the total mass of the present adhesive composition. Moreover, in this adhesive composition, it is preferable to contain a metal corrosion inhibitor in the ratio of 10-200 mass parts with respect to 100 weight part of photoinitiators. By containing in such a mixing ratio, the hardening by the photoinitiator is not inhibited, and the effect of the metal corrosion inhibitor can be utilized to the maximum. From such a viewpoint, the metal corrosion inhibitor is preferably contained in a ratio of 10 to 200 parts by mass with respect to 100 parts by weight of the photoinitiator, and more preferably 12 parts by mass or more or 80 parts by mass or less, especially 15 parts by mass. It is contained in a ratio of not less than 70 parts by mass or not more than 70 parts by mass, especially not less than 20 parts by mass or not more than 50 parts by mass.

The above-mentioned metal corrosion inhibitor has an absorption coefficient at 365 nm of 20 mL/(g·cm) or less, in which 10 mL/(g・cm) or less, especially 5 mL/(g・cm) or less, especially 1 mL/(g・cm) or less is preferable. As a metal corrosion inhibitor having this characteristic, a metal corrosion inhibitor which does not have any skeleton selected from the group consisting of a naphthalene skeleton, an anthracene skeleton, a thiazole skeleton, and a thiadiazole skeleton is preferable. By not having such a skeleton, the metal corrosion inhibitor can have an absorption coefficient in the above-mentioned range.

In addition, the above-mentioned metal corrosion inhibitor is preferably a hydrophilic compound. If the metal corrosion inhibitor is hydrophilic, it is easy to function in an adhesive layer using a (meth)acrylic (co)polymer that is also hydrophilic as a base resin, and thus, for example, it can chemically bond with silver atoms to form It protects the film and suppresses damage (reaction) to metal members, especially silver, by radicals generated from photoinitiators due to light irradiation. From this viewpoint, the water solubility of the metal corrosion inhibitor at 25°C is preferably 20 g/L or more, more preferably 50 g/L or more, especially 100 g/L or more.

From the above viewpoints, as the above-mentioned metal corrosion inhibitor, among metal corrosion inhibitors containing a hydrophilic compound having an absorption coefficient at 365 nm of 20 mL/(g·cm) or less, a triazole-based compound is preferred. Among them, one kind or a mixture of two or more kinds selected from benzotriazole, 1,2,3-triazole and 1,2,4-triazole is particularly preferred. In addition, any substituted or unsubstituted benzotriazole may be used as the benzotriazole, and examples thereof include alkanes such as 1,2,3-benzotriazole and methyl-1H-benzotriazole. benzotriazole, carboxybenzotriazole, 1-hydroxybenzotriazole, 5-aminobenzotriazole, 5-phenylthiol benzotriazole, 5-methoxybenzotriazole , nitrobenzotriazole, chlorobenzotriazole, bromobenzotriazole, fluorobenzotriazole and other halogenated benzotriazoles, copper benzotriazole, silver benzotriazole, benzotriazole silane compounds, etc. Among these, from the viewpoint of dispersibility in the adhesive composition, ease of addition, and metal corrosion prevention effect, those selected from 1,2,3-benzotriazole, 1-[N, N-bis(2-ethylhexyl)aminomethyl]benzotriazole, 1-[N,N-bis(2-ethylhexyl)aminomethyl]methylbenzotriazole, 2,2 '-[[(methyl-1H-benzotriazol-1-yl)methyl]imino]bisethanol, any one or a mixture of two or more of them. Furthermore, 1,2,4-triazole is a solid with a melting point of about 120°C, while 1,2,3-triazole is a substantially liquid state with a melting point of about 20°C and room temperature. Therefore, 1,2,3-triazole has excellent advantages in that it is excellent in dispersibility when mixed in an adhesive composition, can be uniformly mixed, and is easy to be master batched.

＜Properties of this adhesive sheet＞ The adhesive sheet is preferably optically transparent. That is, a transparent adhesive sheet is preferable. Here, "optically transparent" means that the total light transmittance is 80% or more, preferably 85% or more, and more preferably 90% or more.

<Usage form of this adhesive sheet> In addition to directly coating the adhesive composition on the adherend to form a sheet, the adhesive sheet can also be used to form a single-layer or multi-layer sheet-like adhesive sheet with a release film on the release film. . That is, it can be made into an adhesive sheet with a release film sheet which is formed by laminating a release film on at least the front side or the back side of the adhesive sheet.

As a material of the said release film, a polyester film, a polyolefin film, a polycarbonate film, a polystyrene film, an acrylic film, a triacetylcellulose film, a fluororesin film etc. are mentioned, for example. Among these, a polyester film and a polyolefin film are especially preferable.

The above-mentioned release film is preferably one with a transmittance of 40% or less of light with a wavelength of 410 nm or less. At least one area layer of the adhesive sheet has a release film with a transmittance of 40% or less for light with a wavelength of 410 nm or less. Prevent photopolymerization by exposure to visible light. From this point of view, the release film laminated on one or both sides of the adhesive sheet preferably has a light transmittance with a wavelength of 410 nm or less of 40% or less, more preferably 30% or less, especially 20%. the following.

Here, as a release film having a transmittance of 40% or less of light with a wavelength of 410 nm or less, that is, a film having a function of partially blocking the transmission of visible light and ultraviolet light, for example, there are exemplified Propylene-based, polyethylene-based cast film or stretched film is a laminated film formed by coating a micro-adhesive resin with releasability on one side and coating the other side with a coating containing an ultraviolet absorber to form a UV-absorbing layer. Moreover, the micro-adhesive resin which has releasability and which mix|blended with an ultraviolet absorber can be mentioned on one surface of a polypropylene-type, polyethylene-type cast film, or stretched film. Moreover, the micro-adhesive resin which has releasability is applied to a cast film or stretched film containing a polyester-based, polypropylene-based, and polyethylene-based resin prepared with an ultraviolet absorber. In addition, it can be mentioned in the multi-layer casting in which a layer containing a resin containing no ultraviolet absorber is formed on one side or both sides of a layer containing a polyester-based, polypropylene-based, and polyethylene-based resin blended with an ultraviolet absorber. One side of the film or stretched film is coated with releasable micro-adhesive resin. In addition, it is possible to apply a coating containing an ultraviolet absorber to one surface of a cast film or a stretched film containing polyester-based, polypropylene-based, and polyethylene-based resins to provide an ultraviolet-absorbing layer, and further coat the ultraviolet-absorbing layer. Micro-adhesive resin with re-peelability. In addition, it is possible to apply a coating containing an ultraviolet absorber on one side of a cast film or stretched film containing a polyester-based, polypropylene-based, and polyethylene-based resin to provide an ultraviolet absorbing layer, and to coat the other side with releasability. The micro-adhesive resin. In addition, the other surface of a resin film containing polyester-based, polypropylene-based, and polyethylene-based resins coated with a releasable micro-adhesive resin on one side and a separately prepared resin film can be exemplified by containing an ultraviolet absorber. The adhesive layer or the adhesive layer is laminated, etc. The above-mentioned film may have an antistatic layer or other layers such as a hard coat layer, an anchor layer and the like as required.

The thickness of the release film is not particularly limited. Among them, for example, from the viewpoint of workability and handleability, it is preferably 25 μm to 500 μm, and more preferably 38 μm or more or 250 μm or less, especially 50 μm or more or 200 μm or less.

Furthermore, the present pressure-sensitive adhesive sheet can also be formed by a method of directly extruding the present adhesive composition without using an adherend or a release film as described above, or by injecting it into a mold. Furthermore, it can also be set as the form of an adhesive sheet by directly filling this adhesive composition between members, such as a conductive member.

<Application of this adhesive sheet> The adhesive sheet is suitable for image display devices such as personal computers, mobile device terminals (PDA), game consoles, televisions (TV), car navigation systems, touch panels, handwriting pads, etc. The image display device that will constitute the image display device of the image display panel such as liquid crystal display (LCD), organic EL display (OLED), inorganic EL display, electrophoretic display (EPD), interferometric modulation display (IMOD), etc. Glue with constituent members. Moreover, it is especially suitable for bonding the conductive member which consists of the transparent conductive layer which consists of a metal material containing silver. In this case, the conductive member may have an insulating protective film (passivation film).

The adhesive sheet can be used by being attached to a conductive member having a metallic material containing silver, such as a conductive layer of a transparent conductive layer. In this case, any adhesive layer of the adhesive sheet and the conductive layer of the transparent conductive layer may be bonded together. In the case where the adhesive sheet is a double-sided adhesive sheet, the laminated body can be a structure in which two adhesive layers of the adhesive sheet and the conductive layer of the transparent conductive layer are bonded together.

<Laminated body for the constitution of the present image display device> This pressure-sensitive adhesive sheet can be bonded to one or more image display device configuration members to form a layered product for image display device configuration. In particular, it is suitable for forming a laminate for image display device construction by laminating between a constituent member for an image display device including a conductive member formed of a metal material including silver and other constituent members for an image display device via the adhesive sheet body (referred to as the "layered body for configuring this image display device").

In the case of producing the present layered product for image display device configuration using the present photocurable adhesive sheet, the present layered product for image display device configuration can be produced as follows: the above-mentioned two The image display device constituting members are laminated, and then light is irradiated from the side of at least one image display device constituting member to photocur the above-mentioned photocurable pressure-sensitive adhesive sheet.

As a specific example of the laminated body for this image display device structure, a release film/this adhesive sheet/touch panel, an image display panel/this adhesive sheet/touch panel, an image display panel/this adhesive sheet are mentioned, for example /touch panel/this adhesive sheet/protective panel, polarizing film/this adhesive sheet/touch panel, polarizing film/this adhesive sheet/touch panel/this adhesive sheet/protective panel, etc.

Moreover, as the said touch panel, the structure which provided the touch panel function in a protective panel, or the structure which provided the touch panel function in an image display panel is one which contains. Therefore, the layered product for constituting the image display device may be, for example, a release film/the present adhesive sheet/protective panel, a release film/the present adhesive sheet/image display panel, an image display panel/the present adhesive sheet/protective panel, and the like constitute. In addition, among the above-mentioned structures, all structures in which the above-mentioned conductive layers are interposed between the adhesive sheet and adjacent members such as touch panels, protective panels, image display panels, polarizing films, etc., can be mentioned. However, it is not limited to these laminated examples.

In addition, as said touch panel, the thing, such as a resistive film system, an electrostatic capacitance system, and an electromagnetic induction system, is mentioned. In particular, the electrostatic capacitance method is preferable.

As the material of the surface protection panel, in addition to glass, alicyclic polyolefin-based resins such as acrylic resins, polycarbonate-based resins, and cycloolefin polymers, styrene-based resins, polyvinyl chloride-based resins, and phenol-based resins may be used. Resin, melamine resin, epoxy resin and other plastics. As the material of the surface protection panel, in addition to glass, alicyclic polyolefin-based resins such as acrylic resins, polycarbonate-based resins, and cycloolefin polymers, styrene-based resins, polyvinyl chloride-based resins, and phenol-based resins may be used. Resin, melamine resin, epoxy resin and other plastics.

The image display panel includes other optical films such as polarizing film and retardation film, liquid crystal material and backlight system (usually, the adhesive composition or the adhesive article becomes an optical film relative to the adhered surface of the image display panel), according to the The control method of liquid crystal material includes STN (Super Twisted Nematic) method, VA (Vertical Aligned, vertical alignment) method, IPS (In-Plane Switching, lateral electric field effect) method, etc., any method can be used. .

The layered product for forming an image display device can be used, for example, as a constituent member of image display devices such as liquid crystal displays, organic EL displays, inorganic EL displays, electronic paper, plasma displays, and microelectromechanical systems (MEMS) displays. The image display panel includes other optical films such as polarizing film and retardation film, liquid crystal material and backlight system (usually, the adhered surface opposite to the image display panel of the adhesive composition or the adhered article becomes the optical film), Depending on the control method of the liquid crystal material, there are an STN method, a VA method, an IPS method, and the like, and any method may be used.

＜Explanation of words and phrases＞ When expressed as "X to Y" (X and Y are arbitrary numbers) in this specification, unless otherwise stated, the meaning of "more than X and less than Y" is included, and "preferably greater than X" is also included. ” or “preferably less than Y”. In addition, when it is expressed as "more than X" (X is an arbitrary number) or "less than Y" (Y is an arbitrary number), it is also intended to include "preferably greater than X" or "preferably less than Y" meaning. [Example]

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is by no means limited by the following examples.

<Example 1> As the (meth)acrylate (co)polymer (a), 15 parts by mass of a macromonomer (number average molecular weight 2,500) containing a branch component of methyl methacrylate and a main component of 81 mass parts of n-butyl acrylate parts/4 parts by mass of acrylic acid graft copolymer (A-1, mass average molecular weight 300,000, Tg-12°C) 1 kg, 2-hydroxy-4-n-octyloxydiol as ultraviolet absorber (b) Benzophenone (B-1, molecular weight 326.4, melting point 48°C) 5 g, as the photoinitiator (c), the mixture of 2,4,6-trimethylbenzophenone and 4-methylbenzophenone 15 g of mixture (C-1), 100 g of propoxylated pentaerythritol triacrylate (D-1) as crosslinking agent (d), bis(2,2,6, sebacic acid) as lightfast stabilizer (e) 6-Tetramethyl-1-octyloxy-4-piperidin-4-yl) (E-1) 2 g, and 1,2,3-triazole (F) as a metal corrosion inhibitor (f) -1) 2 g was uniformly melt-kneaded to prepare resin composition 1. Furthermore, regarding 1,2,3-triazole (F-1) as a metal corrosion inhibitor, the absorption coefficient at 365 nm is 0.3 mL/(g·cm), and the water solubility at 25°C is more than 1000 g/ L.

Two polyethylene terephthalate films (“DIAFOIL MRF” manufactured by Mitsubishi Chemical Co., Ltd., thickness 75 μm) were used for the resin composition 1, and the thickness was 38 μm (“DIAFOIL MRT” manufactured by Mitsubishi Chemical Co., Ltd. ) was sandwiched and shaped into a sheet shape at a temperature of 80° C. so that the thickness would be 100 μm, and a transparent double-sided adhesive sheet 1 was produced. Furthermore, the adhesive layer of the transparent double-sided adhesive sheet 1 is in an uncured state, and has the property of being photocured by light irradiation.

<Example 2> The macromonomer (number average molecular weight 3,000) 13.5 containing the branch component as the (meth)acrylate (co)polymer (a) is iso-(methyl methacrylate: methyl methacrylate = 1:1) 13.5 Copolymer (A-2, mass-average molecular weight 160,000) 1 kg in parts by mass and the main component is 43.7 parts by mass of lauryl acrylate/40 parts by mass of 2-ethylhexyl acrylate/2.8 parts by mass of acrylamide, as an ultraviolet absorber 5 g of (B-1) as agent (b), 10 g of (C-1) as photoinitiator (c), 100 g of (D-1) as cross-linking agent (d), and as light-resistant stabilizer 2 g of (E-1) of the agent (e) was uniformly melt-kneaded to prepare a resin composition 2. The resin composition 2 was treated with two polyethylene terephthalate films ("DIAFOIL MRF" manufactured by Mitsubishi Chemical Co., Ltd., thickness 75 μm / "DIAFOIL MRT" manufactured by Mitsubishi Chemical Co., Ltd., thickness 38 μm). ) was sandwiched and shaped into a sheet shape at a temperature of 80°C so as to have a thickness of 100 μm to produce a transparent double-sided adhesive sheet 2 . Furthermore, the adhesive layer of the transparent double-sided adhesive sheet 2 is in an uncured state, and has the property of being photocured by light irradiation.

<Example 3> As the (meth)acrylate (co)polymer (a), a copolymer (A) containing 55 parts by mass of 2-ethylhexyl acrylate/20 parts by mass of vinyl acetate/5 parts by mass of acrylic acid was used. -3, mass average molecular weight 400,000) 1 kg, (B-1) 5 g as ultraviolet absorber (b), (C-1) 8 g as photoinitiator (c), and crosslinking agent ( 30 g of (D-1) of d) and 2 g of (E-1) as light resistance stabilizer (e) were uniformly melt-kneaded to prepare resin composition 3. Two polyethylene terephthalate films (“DIAFOIL MRF” manufactured by Mitsubishi Chemical Co., Ltd., thickness 75 μm) were used for the resin composition 3, and the thickness was 38 μm (“DIAFOIL MRT” manufactured by Mitsubishi Chemical Co., Ltd. ) was sandwiched and shaped into a sheet at a temperature of 60°C so as to have a thickness of 100 μm, and was used from a polyethylene terephthalate film side so that the cumulative light intensity at a wavelength of 365 nm became 1500 mJ/cm ² A high-pressure mercury lamp is irradiated with light to pre-harden it, and a transparent double-sided adhesive sheet 3 is produced. Furthermore, the adhesive layer of the transparent double-sided adhesive sheet 3 has room for photohardening by light irradiation.

<Example 4> 1 kg of (A-2) as the (meth)acrylate (co)polymer (a), 5 g of (B-1) as the ultraviolet absorber (b), and 5 g of the photoinitiator (c) 10 g of (C-1), 100 g of (D-1) as a crosslinking agent (d), and 2 g of (F-1) as a metal corrosion inhibitor (f) were uniformly melt-kneaded to prepare a resin Composition 4. Two polyethylene terephthalate films ("DIAFOIL MRF" manufactured by Mitsubishi Chemical Co., Ltd., thickness 75 μm) were used for the resin composition 4, and the thickness was 38 μm manufactured by Mitsubishi Chemical Co., Ltd. ) was sandwiched and shaped into a sheet shape at a temperature of 80° C. so that the thickness would be 100 μm, and a transparent double-sided adhesive sheet 4 was produced. Furthermore, the adhesive layer of the transparent double-sided adhesive sheet 4 is in an uncured state, and has the property of being photocured by light irradiation.

<Example 5> 1 kg of (A-2) as the (meth)acrylate (co)polymer (a), 8 g of (B-1) as the ultraviolet absorber (b), and 8 g of the photoinitiator (c) 8 g of (C-1) and 100 g of (D-1) as a crosslinking agent (d) were uniformly melt-kneaded to prepare a resin composition 5. Two polyethylene terephthalate films ("DIAFOIL MRF" manufactured by Mitsubishi Chemical Co., Ltd., thickness 75 μm) were used for the resin composition 5, and the thickness was 38 μm manufactured by Mitsubishi Chemical Co., Ltd. ) was sandwiched and shaped into a sheet shape at a temperature of 80° C. so as to have a thickness of 100 μm to produce a transparent double-sided adhesive sheet 5 . Furthermore, the adhesive layer of the transparent double-sided adhesive sheet 5 is in an uncured state, and has the property of being photocured by light irradiation.

<Example 6> 1 kg of (A-2) as the (meth)acrylate (co)polymer (a), 8 g of (B-1) as the ultraviolet absorber (b), and 8 g of the photoinitiator (c) (2-hydroxy-2-methyl-1-(4-(1-methylvinyl)phenyl)acetone) oligomer 50 parts by weight/2,4,6-trimethylbenzyl-di 8 g of mixture (C-2) of 46 parts by mass of phenyl-phosphine oxide/3.2 parts by mass of 2,4,6-trimethylbenzophenone/0.8 part by mass of 4-methylbenzophenone, and as 100 g of (D-1) of the crosslinking agent (d) were uniformly melt-kneaded, and a resin composition 6 was produced. Two polyethylene terephthalate films (“DIAFOIL MRF” manufactured by Mitsubishi Chemical Co., Ltd., thickness 75 μm) were used for the resin composition 6, and the thickness was 38 μm “DIAFOIL MRT” manufactured by Mitsubishi Chemical Co., Ltd. ) was sandwiched and shaped into a sheet shape at a temperature of 80° C. so that the thickness would be 100 μm, and a transparent double-sided adhesive sheet 6 was produced. Furthermore, the adhesive layer of the transparent double-sided adhesive sheet 6 is in an uncured state, and has the property of being photocured by light irradiation.

<Example 7> 1 kg of (A-1) as the (meth)acrylate (co)polymer (a), 18 g of (B-1) as the ultraviolet absorber (b), and 18 g of the photoinitiator (c) 20 g of (C-1) and 120 g of (D-1) as a crosslinking agent (d) were uniformly melt-kneaded to prepare a resin composition 7. Two polyethylene terephthalate films ("DIAFOIL MRF" manufactured by Mitsubishi Chemical Co., Ltd., thickness 75 μm) were used for the resin composition 7, and the thickness was 38 μm manufactured by Mitsubishi Chemical Co., Ltd. ) was sandwiched and shaped into a sheet shape at a temperature of 80° C. so that the thickness would be 100 μm, and a transparent double-sided adhesive sheet 7 was produced. Furthermore, the adhesive layer of the transparent double-sided adhesive sheet 7 is in an uncured state, and has the property of being photocured by light irradiation.

<Comparative Example 1> 1 kg of (A-2) as the (meth)acrylate (co)polymer (a) and 2,2-dihydroxy-4-methoxybenzophenone ( B-2, molecular weight 244.2, melting point 73°C) 5 g, (C-1) 10 g as photoinitiator (c), (D-1) 100 g as crosslinking agent (d), and light fastness The stabilizer (e) (E-1) 2 g was melt-kneaded uniformly, and the resin composition 8 was produced. Two polyethylene terephthalate films (“DIAFOIL MRF” manufactured by Mitsubishi Chemical Co., Ltd., thickness 75 μm) were used for the resin composition 8, and the thickness was 38 μm (“DIAFOIL MRT” manufactured by Mitsubishi Chemical Co., Ltd. ) was sandwiched and shaped into a sheet shape at a temperature of 80° C. so that the thickness would be 100 μm, and a transparent double-sided adhesive sheet 8 was produced. Furthermore, the adhesive layer of the transparent double-sided adhesive sheet 8 is in an uncured state, and has the property of being photocured by light irradiation.

<Comparative Example 2> 1 kg of (A-1) as the (meth)acrylate (co)polymer (a), 20 g of (B-1) as the ultraviolet absorber (b), and 20 g of the photoinitiator (c) 15 g of (C-1) and 100 g of (D-1) as a crosslinking agent (d) were uniformly melt-kneaded to prepare a resin composition 9. Two polyethylene terephthalate films (“DIAFOIL MRF” manufactured by Mitsubishi Chemical Co., Ltd., thickness 75 μm) were used for the resin composition 8, and the thickness was 38 μm (“DIAFOIL MRT” manufactured by Mitsubishi Chemical Co., Ltd. ) was sandwiched and shaped into a sheet shape at a temperature of 80° C. so that the thickness would be 100 μm, and a transparent double-sided adhesive sheet 9 was produced. Furthermore, the adhesive layer of the transparent double-sided adhesive sheet 9 is in an uncured state, and has the property of being photocured by light irradiation.

<Comparative Example 3> 1 kg of (A-3) as the (meth)acrylate (co)polymer (a), 8 g of (C-1) as the photoinitiator (c), and 30 g of (D-1) of the agent (d) was uniformly melt-kneaded, and the resin composition 10 was produced. The ultraviolet absorber (b) was not added. Two polyethylene terephthalate films (“DIAFOIL MRF” manufactured by Mitsubishi Chemical Co., Ltd., thickness 75 μm) were used for the resin composition 10, and the thickness was 38 μm “DIAFOIL MRT” manufactured by Mitsubishi Chemical Co., Ltd. ) was sandwiched, shaped into a sheet at a temperature of 60°C so as to have a thickness of 100 μm, and used from a polyethylene terephthalate film side so that the cumulative light intensity at a wavelength of 365 nm became 1000 mJ/cm ² The high-pressure mercury lamp is irradiated with light to pre-harden it, and a transparent double-sided adhesive sheet 10 is produced. Furthermore, the adhesive layer of the transparent double-sided adhesive sheet 10 has room for photohardening by light irradiation.

[Evaluation of physical properties] The physical properties of the transparent double-sided adhesive sheets obtained in Examples and Comparative Examples were measured as follows.

<Gel fraction> The release films of the transparent double-sided adhesive sheets 1 to 10 were peeled off on both sides, and about 0.4 g of the transparent double-sided adhesive sheets 1 to 10 were respectively taken, using SUS (Steel Use Stainless, Japan) whose mass (X) had been measured in advance. A stainless steel standard) mesh (#200) was wrapped into a bag, the bag mouth was folded and sealed, and the mass (Y) of the package was measured. Then, the wrap was immersed in 50 mL of ethyl acetate for 24 hours, then taken out and vacuum-dried at 70° C. for 4.5 hours, the adhered ethyl acetate was evaporated, and the mass (Z) of the dried wrap was measured. , and the obtained mass is obtained by substituting the obtained mass into the following formula. Gel fraction [%]=[(Z-X)/(Y-X)]×100

The measurement samples before photohardening (mainly hardening) used the transparent double-sided adhesive sheets 1 to 10 as the measurement samples as they were. The measurement sample after photocuring (mainly hardening) is to irradiate the transparent double-sided adhesive sheets 1 to 10 with a high-pressure mercury lamp through the release film so that the cumulative light intensity of 365 nm becomes 3000 mJ/cm ² at room temperature. The thing obtained by under-aging for 12 hours was used as a measurement sample.

<Spectroscopic properties> The transparent double-sided adhesive sheets 1 to 10 were directly cut into 50×80 mm using a Thomson punching machine with a release film laminated thereon. The release film on one side was peeled off, and the exposed adhesive surface was manually attached to soda lime glass (54×82 mm, t 0.6 mm). After that, it was vacuum pressure-bonded with another piece of soda lime glass (same as above) (23° C., pressure 0.1 MPa, 1 minute). Then, autoclave treatment (60°C, gauge pressure 0.2 Mpa, 20 minutes) was performed for final processing and bonding, and a high-pressure mercury lamp was used from one glass side to irradiate light in such a way that the cumulative light intensity of 365 nm became 3000 mJ/cm ² to make adhesion. The sheet was photocured and cured at room temperature for 12 hours to prepare a sample for measuring spectroscopic properties. Using these, the spectral characteristics of the transparent double-sided adhesive sheets 1 to 10 were measured under the following conditions. <Apparatus> UV-2450 (manufactured by Shimadzu Corporation) <Wavelength> 300 to 400 nm (measures light transmittance at wavelengths of 320 nm, 340 nm, 365 nm, 380 nm, and 395 nm)

<Storage stability> The transparent double-sided adhesive sheets 1 to 10 were directly cut into 50×50 mm using a Thomson punching machine under the condition that the release film was laminated. These adhesive sheets were allowed to stand still with DIAFOIL MRT (release film) on the upper side, and were irradiated with light with an illuminance of 1100 Lx using a three-wavelength fluorescent lamp for 24 hours. This calculates the change in the gel fraction before and after the storage test under a strong fluorescent lamp.

Next, the storage stability was determined according to the following criteria. After the test, the gel fraction of the adhesive sheet increased significantly, and the gel fraction changed to 20% or more, and it was judged as "X (poor, poor)", and the gel fraction was suppressed to 10% or more and less than 20%. It was judged as "○ (good, good)", and the change in the gel fraction was suppressed to less than 10%, and it was judged as "◎ (very good, very good)".

<Heat-resistant foamability> The transparent double-sided adhesive sheets 1 to 10 were directly cut into 50×80 mm using a Thomson punching machine with a release film laminated thereon. Peel off the release film on one side, and manually attach the exposed adhesive surface to soda lime glass 1 (54×82 mm, t 0.6 mm). Then, peel off the release film on the adhesive side of the adhered polarizer (VLC2 manufactured by Sanritz Company), and manually attach the exposed adhesive surface to soda lime glass 2 (54×82 mm, t 0.6 mm). Furthermore, the protective film on the polarizing plate side was peeled off, and six glass beads (40 μm in diameter) were arranged on the polarizing plate. On the polarizer side, peel off the other release films of the transparent double-sided adhesive sheets 1 to 10 attached to the soda lime glass 1, and manually attach them to the polarizer on which the glass beads are arranged. Next, autoclave treatment (60°C, gauge pressure 0.2 MPa, 20 minutes) was performed for final processing and lamination, and light was irradiated from the soda lime glass 1 side using a high-pressure mercury lamp with a cumulative light intensity of 365 nm to 3000 mJ/cm ² . The adhesive sheet was photocured and cured at room temperature for 12 hours, thereby producing a sample for heat-resistant foamability evaluation (soda-lime glass 1/transparent double-sided adhesive sheet/adhering polarizer/soda-lime glass 2).

This was left to stand for 300 hours in an environment equal to 85°C, and the presence or absence of foaming was visually observed. Those with bubbles at the interface of the polarizing plate/transparent double-sided adhesive sheet etc. were judged as "x (poor)", and those with no bubbles and good appearance were judged as "○ (good)".

<Ultraviolet foam resistance> The transparent double-sided adhesive sheets 1 to 10 were directly cut into 200×150 mm using a Thomson punching machine with a release film laminated thereon. Peel off the release film on one side of the transparent double-sided adhesive sheet, and manually attach the exposed adhesive surface to the entire surface of soda lime glass (200×150 mm, t 0.6 mm). Then, the other release film was peeled off, and the exposed adhesive surface was vacuum pressure-bonded with another piece of soda lime glass (200×150 mm, t 0.6 mm) (23°C, pressing pressure 0.1 MPa, 1 minute). Then, autoclave treatment (60°C, gauge pressure 0.2 MPa, 20 minutes) was carried out for final processing and bonding, and a high-pressure mercury lamp was used from one glass side to irradiate light so that the cumulative light intensity of 365 nm became 3000 mJ/cm ² to make adhesion. The sheet was photocured and cured at room temperature for 12 hours, whereby a sample for evaluation of UV (ultraviolet) foaming property was prepared. This was left to stand for 8 hours/24 hours in the following environment, and the presence or absence of foaming or micro-bubbles under the intense UV irradiation environment was visually observed over time. <Apparatus> SUNTEST CPS+ (manufactured by Toyo Seiki Co., Ltd.) <Light source> Xenon arc lamp (air-cooled, wavelength 270 nm cut-off filter) <Irradiance> 765 W/m ² (wavelength 800 nm or less) <Temperature> BST 63°C

Next, the UV-resistant foamability was judged according to the following criteria. Those with a lot of large foam or micro-bubbles after standing for 3 hours are judged as "X (poor)", the appearance will be good after standing for 3 hours, and there will be foaming or micro-bubbles after standing for 8 hours Those with bubbles were judged as "△ (usual, normal)", those with good appearance after standing for 8 hours and foaming or micro-bubbles after standing for 24 hours were judged as "○ (good)", and those with good appearance after standing for 24 hours were judged as "○ (good)", Those with good appearance were judged as "◎ (very good)".

<Silver Corrosion Resistance> Prepare a silver nanowire film (Activegrid Film manufactured by C3nano, substrate polyethylene terephthalate (thickness 50 μm), surface resistance value 50 Ω/□, with outer coating, full Light transmittance>91%, haze≦0.9%, b*≦1.3) as a conductive member containing silver. As shown in Fig. 1, the silver nanowire film was cut into 45 mm vertical × 80 mm horizontal, and a silver paste (Dotite D manufactured by Fujikura Chemical Co., Ltd., manufactured by Fujikura Chemical Co., Ltd.) was applied vertically with a width of about 3 to 5 mm so that the gap between the electrodes was 50 mm. -550) and dried, and then cut transversely so that the longitudinal width of the sheet becomes 9 mm. The 9 mm×80 mm×5 silver nanowire films with silver paste electrodes were arranged in parallel on soda lime glass. The single-sided release film of the double-sided adhesive sheet cut into a width of 50 mm was peeled off, and the adhesive sheet was placed between the electrodes by means of a roller to stick to it. 20 minutes) for final processing and lamination, and from the side of the adhesive sheet with the release film, the light is irradiated with a high-pressure mercury lamp so that the cumulative light intensity at a wavelength of 365 nm becomes 3000 mJ/cm ² to be photocured.

For this sample, an environmental test was carried out in a humid heat environment of 65°C 90% RH×300 h, and it was confirmed that the resistance value between the electrodes increased. The resistance value increased by more than 10% in the above environmental test was judged as "△ (usual)", and the resistance value increase was suppressed to 10% or less as "○ (good)", and the resistance value increase was further suppressed to 1. % or less is judged as "◎(very good)".

Table 1 shows the evaluation results of Examples and Comparative Examples. Furthermore, in each Example and Comparative Example of Table 1, the (meth)acrylic copolymer (A), the ultraviolet absorber (B), the photoinitiator (C), the crosslinking agent, and the light resistance stabilizer The numerical values described in each item of the metal corrosion inhibitor are parts by mass.

[Table 1] adhesive composition Absorptivity (mL/g・cm) Example Comparative example 340 nm 380 nm 405nm 1 2 3 4 5 6 7 1 2 3 (Meth)acrylic copolymer (A) A-1 - - - 100 - - - - - 100 - 100 - A-2 - - - - 100 - 100 100 100 - 100 - - A-3 - - - - - 100 - - - - - - 100 UV Absorber (B) B-1 5.0E+03 5.8E+02 1.3E+01 0.5 0.5 0.5 0.5 0.8 0.5 1.8 - 2 - B-2 5.0E+03 3.1E+03 4.2E+02 - - - - - - - 0.5 - - Photoinitiator (C) C-1 4.4E+02 8.8E+01 4.0E+00 1.5 1 0.8 1 0.8 - 2 1 1.5 0.8 C-2 4.6E+02 6.2E+02 2.2E+02 - - - - - 0.8 - - - - cross-linking agent D-1 - - - 10 10 3 10 10 10 12 10 10 3 Lightfast Stabilizer E-1 - - - 0.2 0.2 0.2 - - - - 0.2 - - Metal corrosion inhibitor F-1 - - - 0.2 - - 0.2 - - - - - - (B) content in composition quality% 0.4 0.4 0.5 0.4 0.7 0.4 1.6 0.4 1.8 0 ((B)/(C))×100 quality% 33 50 63 50 100 63 90 50 133 0 Cumulative light intensity during pre-hardening - - 1.5 J/cm ² - - - - - - 1 J/cm ² Cumulative amount of light during full hardening 3 J/cm ² 3 J/cm ² 3 J/cm ² 3 J/cm ² 3 J/cm ² 3 J/cm ² 3 J/cm ² 3 J/cm ² 3 J/cm ² 3 J/cm ² adhesive sheet Gel fraction (%) Before formal hardening <5 <5 57 <5 <5 <5 <5 <5 <5 60 After hardening 41 57 69 59 54 32 30 <5 15 74 Spectral Characteristics (Transmittance%) Wavelength 320 nm 0 0 0 0 0 0 0 0 0 37 Wavelength 340 nm 2 2 1 1 0 2 0 0 0 66 Wavelength 365 nm 36 38 39 36 twenty two 38 9 1 5 81 Wavelength 380 nm 64 64 65 65 55 64 41 11 35 86 Wavelength 395 nm 83 84 85 84 81 84 77 52 75 90 Storage stability ◎ ◎ ◎ ◎ ◎ 〇(18) ◎ ◎ ◎ ◎ Heat-resistant foamability 〇 〇 〇 〇 〇 〇 〇 × × 〇 UV resistant foaming 〇 ◎ 〇 ◎ ◎ ◎ △ × × × Silver corrosion resistance 〇 △ △ ◎ △ △ △ △ △ △

Regarding the transparent double-sided adhesive sheets of Examples 1 to 7, by using an ultraviolet absorber and a photoinitiator having a specific absorption coefficient and controlling the amount of these additions, it is possible to suppress exposure to light without inhibiting photohardening. Deterioration of the adhesive sheet itself can be suppressed, especially in a UV irradiation environment, and it is excellent in UV foam resistance. Especially the transparent double-sided adhesive sheets of Examples 1 to 5 and 7, since the light absorption coefficient of the photoinitiator at 405 nm is small, it is not easy for the adhesive to photoharden even when stored under a fluorescent lamp with high illuminance. , and those with excellent storage stability. Furthermore, in Examples 1 and 4, a metal corrosion inhibitor was added, and they were excellent in resistance to silver metal corrosion. Among them, Example 4, which does not contain carboxylic acid in the (meth)acrylate (co)polymer (a), is extremely excellent in silver corrosion resistance, when it is attached to a conductive member formed of a metal material containing silver can also be used optimally.

In contrast, the transparent double-sided adhesive sheet 7 of Comparative Example 1 uses an ultraviolet absorber with a high absorption coefficient at a wavelength of 380 nm, which hinders the activation of the photoinitiator. It also does not fully photo-harden, and is poor in heat-resistant reliability or UV-resistant reliability. In Comparative Example 2 in which more ultraviolet absorbers were added to the photoinitiators, the ultraviolet absorbers themselves plasticized the adhesive sheet or hindered the activation of the photoinitiators to a certain extent, and the agglomeration after photohardening occurred. The force will be lower, so it is inferior to heat-resistant reliability or UV-resistant reliability. The transparent double-sided adhesive sheet that does not contain an ultraviolet absorber such as Comparative Example 3 cannot suppress the deterioration of the adhesive sheet itself when exposed to ultraviolet rays, and a large amount of decomposition products (outgassing) are generated from the adhesive sheet. Foaming or peeling occurred in the foam test. [Industrial Availability]

Since the pressure-sensitive adhesive sheet of the present invention is excellent in heat-resistant foaming property or ultraviolet-resistant foaming property, storage stability, and corrosion resistance, it can be applied to optical applications, especially image display device applications.

1 is a diagram for explaining the evaluation test method for the reliability of silver corrosion resistance in the examples described below, (A) is a plan view of a sample for evaluating the reliability of silver corrosion resistance, (B) is the reliability of silver corrosion resistance Cross-sectional view of the sample for evaluation.

Claims (18)

A photocurable adhesive sheet, characterized in that it has an adhesive layer formed from an adhesive composition containing an ultraviolet absorber and a photoinitiator, wherein the absorption coefficient of the ultraviolet absorber at a wavelength of 340 nm is 1×10 ³ mL/(g·cm) or more, and the absorption coefficient at a wavelength of 380 nm is less than 1×10 ³ mL/(g·cm), the above-mentioned adhesive composition relative to the total mass of the adhesive composition is 0.1～1.6 The ratio by mass % contains the above-mentioned ultraviolet absorber, and the gel fraction of the adhesive sheet is 5% or less. The photocurable adhesive sheet according to claim 1, wherein the adhesive composition contains the ultraviolet absorber in a ratio of 0.1 to 1.4 mass % with respect to the total mass of the adhesive composition. The photocurable adhesive sheet according to claim 1 or 2, wherein the adhesive composition contains the ultraviolet absorber in a ratio of 30 to 100 parts by mass with respect to 100 parts by mass of the photoinitiator. The photocurable adhesive sheet of claim 1 or 2, wherein the absorption coefficient of the above-mentioned photoinitiator at a wavelength of 405 nm is less than 10 mL/(g·cm). The photocurable adhesive sheet according to claim 1 or 2, wherein the photoinitiator is a hydrogen abstraction type photoinitiator. The photocurable adhesive sheet of claim 1 or 2, wherein the adhesive composition further comprises a (meth)acrylate (co)polymer that does not contain a carboxyl group-containing monomer as a structural unit. The photocurable adhesive sheet according to claim 6, wherein the (meth)acrylate (co)polymer has a chemical bond formed by a combination of a hydroxyl group and an isocyanate group, or an amine group and an isocyanate group. . The photocurable adhesive sheet according to claim 7, wherein the (meth)acrylate (co)polymer further has a radically polymerizable functional group. The photocurable adhesive sheet according to claim 6, wherein the (meth)acrylate (co)polymer is a graft copolymer having a macromonomer as a branch component. The photocurable adhesive sheet according to claim 1 or 2, wherein the adhesive composition further contains a metal corrosion inhibitor. The photocurable adhesive sheet of claim 10, wherein the absorption coefficient at 365 nm of the above-mentioned metal corrosion inhibitor is 20 mL/(g·cm) or less. The photocurable adhesive sheet of claim 10, wherein the water solubility of the metal corrosion inhibitor at 25°C is 20 g/L or more. The photocurable adhesive sheet according to claim 10, wherein the metal corrosion inhibitor is a triazole-based compound. The photocurable adhesive sheet according to claim 10, wherein the adhesive composition contains the metal corrosion inhibitor in a ratio of 0.05 to 2.0 mass % with respect to the total mass of the adhesive composition. The photocurable adhesive sheet according to claim 10, wherein the adhesive composition contains a metal corrosion inhibitor in a ratio of 10 to 200 parts by mass with respect to 100 parts by mass of the photoinitiator. An adhesive sheet with a release film, comprising the photocurable adhesive sheet as claimed in any one of claims 1 to 15, and a light transmittance layered on at least the front side or the back side of the adhesive sheet and having a wavelength below 410 nm A release film with a light rate of less than 40%. A laminated body for image display device construction, which is formed using the photocurable adhesive sheet according to any one of claims 1 to 15, and one or more image display device construction members. An image display device formed using the layered body for forming an image display device as claimed in claim 17.

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