CN110997849B - Adhesive sheet, laminate for image display device construction, and image display device - Google Patents

Abstract

Disclosed is a photocurable adhesive sheet containing an ultraviolet absorber, which is characterized by being provided with: a novel adhesive sheet having ultraviolet ray foamability resistance without impairing photocurability. A pressure-sensitive adhesive sheet characterized by having a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing an ultraviolet absorber and a photoinitiator, wherein the ultraviolet absorber has an absorption coefficient of 1 x 10 at a wavelength of 340nm ³ mL/(g cm) or more and an absorption coefficient at a wavelength of 380nm of less than 1X 10 ³ mL/(g cm), the adhesive composition contains an ultraviolet absorber in a ratio of 0.1 to 1.6 mass% relative to the total mass of the adhesive composition.

Description

Adhesive sheet, laminate for image display device construction, and image display device

Technical Field

The present invention relates to: disclosed is a pressure-sensitive adhesive sheet, particularly a pressure-sensitive adhesive sheet having ultraviolet ray foamability resistance, which comprises a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing an ultraviolet ray absorber and a photoinitiator.

Background

In image display devices such as personal computers, mobile terminals (PDAs), game machines, televisions (TVs), car navigation systems, touch panels, and tablet personal computers, for example, in image display devices using flat or curved image display panels such as Plasma Display Panels (PDPs), liquid Crystal Displays (LCDs), organic EL displays (OLEDs), electrophoretic displays (EPDs), and Interferometric Modulators (IMODs), the following operations are performed in order to ensure visibility and prevent breakage: the components are bonded and integrated by an adhesive sheet or a liquid adhesive without providing a gap between the components.

For example, in an image display device having a configuration in which a touch panel is inserted between a visible side of a liquid crystal module and a surface protection panel, the following operations are performed: a liquid adhesive or an adhesive sheet is disposed between the surface protection panel and the visible side of the liquid crystal module, and the touch panel is bonded and integrated with other components, for example, the touch panel and the liquid crystal module, and the touch panel and the surface protection panel.

As a method for filling the gap between the constituent members for an image display device with such an adhesive, patent document 1 discloses the following method: after filling the gap with a liquid adhesive resin composition containing an ultraviolet curable resin, ultraviolet rays are irradiated to cure the composition.

Further, a method of filling a gap between constituent members for an image display device with an adhesive sheet is also known. For example, patent document 2 discloses the following method: after the pressure-sensitive adhesive sheet crosslinked 1 time by ultraviolet rays was attached to an image display device constituting member, the pressure-sensitive adhesive sheet was cured 2 times by ultraviolet irradiation through the image display device constituting member.

However, there is a concern about deterioration by ultraviolet rays in an optical member used in an image display device, and ultraviolet absorbability is sometimes required for an adhesive sheet for the purpose of preventing the deterioration.

For example, as such a pressure-sensitive adhesive sheet, patent documents 3 and 4 propose a transparent pressure-sensitive adhesive sheet in which an ultraviolet absorber is contained in a pressure-sensitive adhesive layer.

Documents of the prior art

Patent document

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 laid-open patent publication No. 2015-229759

Disclosure of Invention

Problems to be solved by the invention

Various purposes exist for imparting ultraviolet absorptivity to a pressure-sensitive adhesive sheet.

For example, the following objects can be mentioned: the optical member adjacent to the adhesive sheet is prevented from being deteriorated due to long-term exposure to ultraviolet rays.

However, for this purpose, it is necessary to contain a large amount of an ultraviolet absorber and to have light shielding properties in a wide wavelength range of 380nm or more.

Therefore, when such an ultraviolet absorber is contained in the photocurable adhesive sheet, it is considered that the photocurability thereof is not inhibited by the action of the ultraviolet absorber by using a photoinitiator having reactivity in a wide range from the ultraviolet to visible light regions.

However, if such a photoinitiator is used, there is a problem that photocuring proceeds slowly when the photocurable adhesive sheet is stored under a fluorescent lamp, for example.

On the other hand, ultraviolet rays deteriorate not only the optical member but also the adhesive sheet itself, and there is a possibility that foaming or peeling occurs due to decomposition products (outgassing) generated by deterioration of the adhesive sheet. Therefore, a property of withstanding foaming in the adhesive sheet caused by exposure to ultraviolet rays (referred to as "ultraviolet ray foaming resistance") is required.

In order for the adhesive sheet to have such ultraviolet ray foaming resistance, the adhesive sheet after photocuring needs to have sufficient cohesive force to withstand exhaust gas.

However, when an ultraviolet absorber is contained in a photocurable adhesive sheet, if the content of the ultraviolet absorber is simply increased in order to reduce the influence of ultraviolet rays, the ultraviolet absorber may act as a plasticizer and interfere with the photocuring of the adhesive sheet, and therefore, it is necessary to make studies from a viewpoint completely different from such a viewpoint.

Accordingly, the present invention relates to a photocurable pressure-sensitive adhesive sheet containing an ultraviolet absorber, and provides: a novel adhesive sheet having ultraviolet ray foamability resistance without impairing photocurable properties.

Means for solving the problems

The invention provides a pressure-sensitive adhesive sheet characterized by comprising a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing an ultraviolet absorber and a photoinitiator, wherein the ultraviolet absorber has an absorption coefficient of 1 x 10 at a wavelength of 340nm ³ mL/(g cm) or more and an absorption coefficient at a wavelength of 380nm of less than 1X 10 ³ mL/(g cm), the pressure-sensitive adhesive composition contains the ultraviolet absorber in a ratio of 0.1 to 1.6% by mass relative to the total mass of the pressure-sensitive adhesive composition.

ADVANTAGEOUS EFFECTS OF INVENTION

The pressure-sensitive adhesive sheet proposed by the present invention can enjoy a desired effect by using an ultraviolet absorber having a specific absorption coefficient in a specific wavelength region and by limiting the content ratio of the ultraviolet absorber. That is, the ultraviolet absorber prevents transmission of ultraviolet rays on the short wavelength side, and therefore, even if the adhesive sheet is exposed to ultraviolet rays, the outgas generated from the adhesive sheet can be reduced. In this case, by limiting the content of the ultraviolet absorber, the ultraviolet absorber itself functions as a plasticizer, and a decrease in the cohesive force of the adhesive sheet can be prevented, and heat-resistant foaming properties at high temperatures can be obtained.

Further, by using a substance having an absorption coefficient at a wavelength of 405nm of less than 10 mL/(g · cm) as the photoinitiator, the photoinitiator is not activated in the visible light wavelength region, and therefore, photocuring can be prevented even when stored in a visible light exposure environment such as under a fluorescent lamp.

Further, by limiting the content ratio of the ultraviolet absorber and the metal corrosion inhibitor, particularly by using a specific metal corrosion inhibitor, it is possible to obtain metal corrosion resistance without inhibiting photocuring by the photoinitiator.

Drawings

Fig. 1 is a diagram for explaining a test method for evaluating reliability against silver corrosion in examples described later, (a) is a plan view of a sample for evaluating reliability against silver corrosion, and (B) is a cross-sectional view of the sample for evaluating reliability against silver corrosion.

Detailed Description

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

< present pressure-sensitive adhesive sheet >

A pressure-sensitive adhesive sheet according to an embodiment of the present invention (hereinafter referred to as "the present pressure-sensitive adhesive sheet") has a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing an ultraviolet absorber and a photoinitiator (hereinafter referred to as "the present pressure-sensitive adhesive composition").

The present adhesive sheet may have a multilayer structure of at least 1 or more layers of the adhesive layer, and may have a multilayer structure of at least 2 layers, and in the case of a multilayer structure, another layer such as a base layer may be interposed. In the above case, all the adhesive layers may be formed of the present adhesive composition as long as at least the outermost layer is formed of the present adhesive composition.

(thickness of the adhesive sheet)

The thickness of the adhesive sheet is preferably 10 μm or more and 500 μm or less.

The thickness reduction can satisfy the demand for the reduction in thickness, while if the thickness is excessively reduced, for example, when the surface to be bonded has irregularities, the adhesion may not sufficiently follow the irregularities or may not exhibit sufficient adhesive force.

From this viewpoint, the thickness of the present pressure-sensitive 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 more preferably 20 μm or more or 350 μm or less.

< present adhesive composition >

The adhesive composition contains an ultraviolet absorber and a photoinitiator. In addition to these, a (meth) acrylate (co) polymer, a crosslinking agent, a metal corrosion inhibitor and other components may be contained as necessary.

It is to be noted that the term "(co) polymer" is used in a meaning including homopolymers and copolymers, and the term "(meth) acrylate" is used in a meaning including acrylates and methacrylates.

(ultraviolet absorber)

The ultraviolet absorber preferably has an absorption coefficient of 1X 10 at a wavelength of 340nm ³ mL/(g cm) or more and an absorption coefficient at a wavelength of 380nm of less than 1X 10 ³ mL/(g·cm)。

The ultraviolet absorber has such light absorption characteristics that the wavelength region of absorbed ultraviolet rays is narrow, and further, has such a property that ultraviolet rays of only shorter wavelengths are shielded, and hence curing by the photoinitiator which interferes with the adhesive sheet can be suppressed.

Further, even if the content of the ultraviolet absorber is reduced, the ultraviolet-ray-resistant foamability can be obtained.

From the above viewpoint, the absorption coefficient of the ultraviolet absorber at a wavelength of 340nm is more preferably 2X 10 ³ mL/(g.cm) or more, wherein 3X 10 ³ mL/(g.cm) or more, more preferably 3.5X 10 ³ mL/(g cm) or more.

Further, the absorption coefficient of the ultraviolet absorber at a wavelength of 380nm is more preferably less than 8X 10 ² mL/(g cm), wherein it is less than 7X 10 ² mL/(g.cm), among others, more preferably less than 6X 10 ² mL/(g·cm)。

More preferably, the ultraviolet absorber has an absorption coefficient at a wavelength of 405nm of less than 1X 10 ² mL/(g·cm)。

The absorption coefficient of the ultraviolet absorber having a wavelength of 405nm is in this range, whereby the color tone, specifically, the yellow color tone of the adhesive sheet can be suppressed. In addition, the change in color tone can be suppressed.

From the above viewpoint, the absorption coefficient of the ultraviolet absorber at a wavelength of 405nm is preferably less than 1X 10 ² mL/(g cm), wherein it is less than 8X 10 ¹ mL/(g.cm), among others, more preferably less than 5X 10 ¹ mL/(g·cm)。

The melting point of the ultraviolet absorber is preferably 100 ℃ or lower.

When the melting point of the ultraviolet absorber is 100 ℃ or lower, the dispersibility when it is mixed into the adhesive composition is excellent, and the uniform mixing is facilitated.

Accordingly, the ultraviolet absorber preferably has a melting point of 100 ℃ or lower, more preferably-50 ℃ or higher or 50 ℃ or lower.

Examples of the ultraviolet absorber include those having 1 or 2 or more structures selected from the group consisting of a benzotriazole structure, a benzophenone structure, a triazine structure, a benzoate structure, an oxanilide structure, a salicylate structure, and a cyanoacrylate structure, and those having a predetermined absorption coefficient may be selected from these structures.

Among them, from the viewpoints of adjustment of the above absorption coefficient, compatibility with a binder, stability when added together with other various additives, and the like, it is preferable to select one having a benzophenone structure.

The absorption coefficient at a measurement wavelength of 340nm can be measured as follows: for example, the absorbance of a solution diluted with a solvent (acetonitrile or acetone) which does not absorb light of a measurement wavelength can be measured by placing the solution in a quartz cuvette and measuring the absorbance. The absorption coefficient can be obtained from the following equation.

α340＝A340×d/c

α 340: absorption coefficient at wavelength of 340nm [ mL/(g cm) ]

A340: absorbance at wavelength of 340nm

c: concentration of solution [ g/mL ]

d: optical path length (of quartz cuvette) [ cm ]

In addition, when calculating the absorption coefficient, absorbance converted from the measurement result of the transmittance may be used.

A340＝-Log(T340/100)

T340: light transmittance [% ] at wavelength of 340nm

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

The pressure-sensitive adhesive composition preferably contains the ultraviolet absorber in a proportion of 0.1 to 1.6% by mass relative to the total mass of the pressure-sensitive adhesive composition.

By containing the ultraviolet absorber in the above ratio, the adhesive sheet is free from the fear of curing inhibition during photocuring, and moreover, sufficient cohesive force can be imparted to the adhesive sheet without plasticizing the adhesive more than necessary by the ultraviolet absorber, so that the adhesive sheet can have excellent ultraviolet foamability resistance.

From the above-mentioned viewpoint, the ultraviolet absorber is preferably contained in a ratio of 0.1 to 1.6% by mass, more preferably 0.2% by mass or more or 1.4% by mass or less, particularly 0.3% by mass or more or 1.0% by mass or less, and further particularly 0.4% by mass or more or 0.9% by mass or less, based on the total mass (100% by mass) of the adhesive composition.

From the above, the ultraviolet absorber is contained preferably at a ratio of 0.1 to 1.4% by mass, 0.1 to 1.0% by mass, or 0.1 to 0.9% by mass, more preferably at a ratio of 0.2 to 1.6% by mass, 0.2 to 1.4% by mass, 0.2 to 1.0% by mass, or 0.2 to 0.9% by mass, further preferably at a ratio of 0.3 to 1.6% by mass, 0.3 to 1.4% by mass, 0.3 to 1.0% by mass, or 0.3 to 0.9% by mass, and most preferably at a ratio of 0.4 to 1.6% by mass, 0.4 to 1.4% by mass, 0.4 to 1.0% by mass, or 0.4 to 0.9% by mass, relative to the total mass (100% by mass) of the adhesive composition.

From the same viewpoint, the ultraviolet absorber is preferably contained in a proportion of 30 to 100 parts by mass, more preferably 40 parts by mass or more or 95 parts by mass or less, and further preferably 50 parts by mass or more or 90 parts by mass or less, based on 100 parts by mass of the photoinitiator in the adhesive composition.

(photoinitiator)

As the photoinitiator, a photoinitiator having an absorption coefficient at a wavelength of 405nm of less than 10 mL/(g.cm) is particularly preferable.

Since the photoinitiator having such an absorption coefficient has low activity in the visible light region, the possibility of photocuring is low even when stored in a fluorescent lamp, and a pressure-sensitive adhesive sheet having excellent storage stability can be obtained.

From the above-mentioned viewpoints, it is more preferable to use a photoinitiator having an absorption coefficient at a wavelength of 405nm of less than 8 mL/(g.cm), and it is particularly preferable to use a photoinitiator having an absorption coefficient at a wavelength of 405nm of 5 mL/(g.cm) or less.

Photoinitiators are roughly classified into 2 types according to the mechanism of radical generation, roughly: a cleavage type photoinitiator which can generate a radical by cleaving and decomposing a single bond of the photoinitiator itself; and a hydrogen abstraction initiator, wherein the initiator after photoexcitation forms an excited complex with a hydrogen donor in the system, and hydrogen of the hydrogen donor can be transferred.

Among these, the photoinitiator contained in the adhesive composition is preferably a hydrogen abstraction type initiator.

In the case of the hydrogen abstraction type, the cohesive force after photocuring is easily obtained, and the durability such as heat-resistant foaming property is excellent.

Further, unlike the cracking type, since there is no fear that the decomposition product may adversely affect the corrosion, it is easy to balance the metal corrosion resistance, and it is possible to perform the photo-curing even in a state where the photo-curing property remains.

Examples of the cleavage type photoinitiators include 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- (4- (2-hydroxyethoxy) phenyl) -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1- [4- {4- (2-hydroxy-2-methylpropiono) benzyl } phenyl ] -2-methyl-propan-1-one, oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone), phenylglyoxylic acid methyl ester, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butan-1-one, 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one, 2- (dimethylamino) -2- [ (4-methylphenyl) methyl) -1- [4- (morpholinophenyl ] -354-morpholinophenyl ] -3532-trimethylbenzoylphenylphosphine oxide, 3425-benzoylbenzoylphenylphosphine oxide, and the like, (2,4,6-trimethylbenzoyl) ethoxyphenylphosphine oxide, their derivatives, and the like.

Among them, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide and 2,4,6-trimethylbenzoyl diphenylphosphine oxide are particularly preferable.

Examples of the hydrogen abstraction photoinitiator include benzophenone, michler's ketone, 2-ethylanthraquinone, thioxanthone, and derivatives thereof.

Among the above photoinitiators, a hydrogen abstraction photoinitiator having an absorption coefficient at a wavelength of 405nm of less than 10 mL/(g cm) is particularly preferable in terms of easier achievement of cohesive force after photocuring as compared with a cleavage type photoinitiator.

< (meth) acrylate (co) Polymer >

The present adhesive composition may comprise a (meth) acrylate (co) polymer.

Examples of the (meth) acrylate (co) polymer include, in addition to homopolymers of alkyl (meth) acrylates: a copolymer obtained by polymerizing the monomer component with copolymerizability.

More preferable (meth) acrylate (co) polymers include: a copolymer comprising, as a structural unit, an alkyl (meth) acrylate and at least one monomer selected from the group consisting of a hydroxyl group-containing monomer copolymerizable therewith, an amino group-containing monomer, an epoxy group-containing monomer, an amide group-containing monomer and another vinyl monomer.

Among them, if a highly polar component such as a carboxyl group is used as a copolymerization component, an adherend, particularly, a conductive member such as an ITO film or an IGZO film is oxidatively deteriorated due to its oxidation, and therefore, in order to suppress corrosion of a metal member, a (meth) acrylate (co) polymer containing no carboxyl group-containing monomer as a structural unit is preferable.

The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition containing such a (meth) acrylate (co) polymer is preferably photo-cured by light irradiation.

The phrase "does not contain a carboxyl group-containing monomer as a structural unit" means "does not substantially contain", that is, means "does not intend to contain". Among them, there are cases where inclusion is unavoidable, and therefore, not only the case where inclusion is completely excluded, but also the case where the copolymerizable monomer a is included in the (meth) acrylate (co) polymer at less than 0.5 mass%, preferably less than 0.1 mass%.

The (meth) acrylate (co) polymer can be produced by a conventional method using the following exemplified monomers and the like, if necessary, a polymerization initiator.

Examples of more specific (meth) acrylate (co) polymers include: a copolymer comprising a (meth) acrylate having a linear or branched alkyl group having 4 to 18 carbon atoms in the side chain (hereinafter also referred to as "copolymerizable monomer A") and at least one monomer component copolymerizable therewith selected from the group consisting of B to E.

Macromonomer (hereinafter also referred to as "copolymerizable monomer B")

(meth) acrylate having 1 to 3 carbon atoms in the side chain (hereinafter also referred to as "copolymerizable monomer C")

Hydroxyl group-containing monomer (hereinafter also referred to as "copolymerizable monomer D")

Other vinyl monomer (hereinafter, also referred to as "copolymerizable monomer E")

Among them, examples of the (meth) acrylate (co) polymer include (a) a copolymer composed of monomer components including a copolymerizable monomer a and a copolymerizable monomer B; (b) A copolymer composed of monomer components including a copolymerizable monomer a, a copolymerizable monomer C, and a copolymerizable monomer D and/or a copolymerizable monomer E is a suitable example.

(copolymerizable monomer A)

Examples of the (meth) acrylate having a linear or branched alkyl group having 4 to 18 carbon atoms in the side chain (copolymerizable monomer A) include n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (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, isooctyl (meth) acrylate, 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, hexadecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, behenyl (meth) acrylate, isobornyl (meth) acrylate, zxft 8978-trimethylcyclohexyl (meth) acrylate, dicyclopentyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, benzyl (meth) acrylate, and the like. These can be used in 1 kind or in combination of 2 or more kinds.

The copolymerizable monomer a is contained in an amount of preferably 30 to 90% by mass, more preferably 35 to 88% by mass, and particularly preferably 40 to 85% by mass, based on the total monomer components of the copolymer.

(copolymerizable monomer B)

The macromonomer (copolymerizable monomer B) is a monomer having a side chain of 20 or more carbon atoms when a (meth) acrylate (co) polymer is formed by polymerization. By using the copolymerizable monomer B, the (meth) acrylate (co) polymer can be formed 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 of the copolymerizable monomer B, and monomers other than the copolymerizable monomer B, and the compounding ratio.

The macromonomer (copolymerizable monomer B) is preferably composed of an acrylate copolymer or a vinyl polymer as a backbone component.

Examples of the backbone component of the macromonomer include the copolymerizable monomer a, the copolymerizable monomer C described below, and the copolymerizable monomer D described below, and these can be used alone or in combination of 2 or more.

The macromonomer has a radical polymerizable group or a functional group such as a hydroxyl group, an isocyanate group, an epoxy group, a carboxyl group, an amino group, an amide group, or a mercapto group.

The macromonomer preferably has a radical polymerizable group copolymerizable with other monomers. The radical polymerizable group may contain one or more, and among them, one is particularly preferable. When the macromonomer has a functional group, the functional group may contain one or more, and among them, one is particularly preferable. The radical polymerizable group and the functional group may contain either one or both of them.

The number average molecular weight of the copolymerizable monomer B is preferably 500 to 2 ten thousand, more preferably 800 or more and 8000 or less, particularly 1000 or more and 7000 or less.

As the macromonomer, a general manufacturer (for example, a macromonomer manufactured by Toyo Synthesis Co., ltd.) can be suitably used.

The copolymerizable monomer B is preferably contained in an amount of 5 to 30% by mass, particularly 6 to 25% by mass, and particularly 8 to 20% by mass, of the total monomer components of the copolymer.

Examples of the (meth) acrylate (co) polymer composed of the copolymerizable monomer B include: a (meth) acrylate copolymer (a-1) comprising a graft copolymer having a macromonomer as a branched component.

When the pressure-sensitive adhesive layer is formed of such a (meth) acrylate copolymer (a-1), the pressure-sensitive adhesive layer can be maintained in a sheet form at room temperature and exhibits self-adhesiveness, has a hot-melt property of melting or flowing when heated, can be further photo-cured, and can be bonded by exhibiting excellent cohesive force after photo-curing.

Thus, when the (meth) acrylate copolymer (a-1) is used, it exhibits adhesiveness at room temperature (20 ℃) even in an uncrosslinked state, and can have the property of softening or fluidizing when heated to a temperature of 50 to 100 ℃, more preferably 60 ℃ or higher or 90 ℃ or lower.

Since the glass transition temperature of the copolymer component constituting the dry component of the (meth) acrylate copolymer (a-1) has an influence on the flexibility of the pressure-sensitive adhesive layer in a room temperature state and the wettability of the pressure-sensitive adhesive layer to an adherend, i.e., the adhesiveness, the glass transition temperature is preferably-70 ℃ to 0 ℃, particularly preferably-65 ℃ or more or-5 ℃ or less, and particularly preferably-60 ℃ or more or-10 ℃ or less, in order to obtain a proper adhesiveness (tackiness) of the pressure-sensitive adhesive sheet 1 in a room temperature state.

However, even if the glass transition temperature of the copolymer component is the same, the viscoelasticity can be adjusted by adjusting the molecular weight. For example, by reducing the molecular weight of the copolymer component, further softening is possible.

(copolymerizable monomer C)

Examples of the (meth) acrylate having 1 to 3 carbon atoms in the side chain (the copolymerizable monomer C) include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and the like. These may be 1 or 2 or more in combination.

The copolymerizable monomer C is contained in the total monomer components of the copolymer in an amount of preferably 0 to 70 mass%, more preferably 3 to 65 mass%, and particularly preferably 5 to 60 mass%.

(copolymerizable monomer D)

Examples of the hydroxyl group-containing monomer (copolymerizable monomer D) include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate. These may be 1 or 2 or more in combination.

The copolymerizable monomer D is preferably contained in an amount of 0 to 30% by mass, more preferably 0 to 25% by mass, and particularly preferably 0 to 20% by mass, based on the total monomer components of the copolymer.

(copolymerizable monomer E)

Examples of the other vinyl monomer (copolymerizable monomer E) include compounds having a vinyl group in the molecule other than the copolymerizable monomers a to D.

As such a compound, there can be exemplified: functional monomers having a functional group such as an amide group or an alkoxyalkyl group in the molecule, polyalkylene glycol di (meth) acrylates, vinyl ester monomers such as vinyl acetate, vinyl propionate and vinyl laurate, and aromatic vinyl monomers such as styrene, chlorostyrene, chloromethylstyrene, α -methylstyrene and other substituted styrenes. These may be 1 or 2 or more in combination.

The copolymerizable monomer E is contained in an amount of preferably 0 to 30% by mass, more preferably 0 to 25% by mass, and particularly preferably 0 to 20% by mass, based on the total monomer components of the copolymer.

In addition to those described above, the following may be used as appropriate as necessary: epoxy group-containing monomers such as glycidyl (meth) acrylate, glycidyl alpha-ethacrylate, and (meth) acrylic acid-3,4-epoxybutyl ester; amino group-containing (meth) acrylate monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; amide group-or imide group-containing monomers such as (meth) acrylamide, N-t-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone (meth) acrylamide, maleimide, and the like; and heterocyclic basic monomers such as vinylpyrrolidone, vinylpyridine, and vinylcarbazole.

Among the above, suitable examples of the (meth) acrylate (co) polymer include: the (meth) acrylate copolymer is obtained by copolymerizing monomer components including a monomer component (a) selected from any 1 or more selected from the group consisting of 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, decyl (meth) acrylate, isostearyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, butyl (meth) acrylate, ethyl (meth) acrylate, and methyl (meth) acrylate, and a monomer component (b) selected from any 1 or more selected from the group consisting of hydroxyethyl (meth) acrylate having an organic functional group or the like, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, glycerol (meth) acrylate, glycidyl (meth) acrylate, meth) acrylamide, meth) acrylonitrile, fluorinated (meth) acrylate, and silicone (meth) acrylate.

Further, examples of preferable (meth) acrylate (co) polymers include: a chemical bond formed by a combination of a hydroxyl group and an isocyanate group or an amino group and any functional group of the isocyanate groups; or a graft copolymer having a macromonomer as a branch component.

The mass average molecular weight of the (meth) acrylate (co) polymer is preferably 10 ten thousand or more and 150 ten thousand or less, particularly 15 ten thousand or more or 130 ten thousand or less, and particularly 20 ten thousand or more or 120 ten thousand or less.

In the case of obtaining an adhesive composition having a high cohesive force, the mass average molecular weight of the (meth) acrylate (co) polymer is preferably 70 to 150 ten thousand, particularly 80 to 130 ten thousand, from the viewpoint that the higher the molecular weight, the more the cohesive force can be obtained by entanglement of the molecular chains.

On the other hand, when an adhesive composition having high fluidity and stress relaxation property is desired, the mass average molecular weight is preferably 10 to 70 ten thousand, particularly 15 to 60 ten thousand.

On the other hand, when a solvent is not used in molding into an adhesive sheet or the like, it is difficult to use a polymer having a large molecular weight.

Thus, the mass average molecular weight of the (meth) acrylate (co) polymer is more preferably 10 to 70 ten thousand, particularly 15 to 60 ten thousand, particularly 20 to 50 ten thousand.

(crosslinking agent)

The present adhesive composition may contain a crosslinking agent as needed.

By adding the crosslinking agent, the degree of crosslinking, in other words, the gel fraction can be increased, and the cohesive force can be increased.

For example, the following methods can be mentioned as a method for crosslinking the (meth) acrylate (co) polymer: a method of adding a crosslinking agent capable of chemically bonding to a reactive group such as a hydroxyl group or a carboxyl group introduced into the (meth) acrylate (co) polymer, and reacting the resulting mixture by heating or aging; a method of adding a polyfunctional (meth) acrylate having 2 or more (meth) acryloyl groups as a crosslinking agent and a reaction initiator such as a photoinitiator, and crosslinking the resulting mixture by ultraviolet irradiation or the like.

Among them, a crosslinking method by irradiation with light such as ultraviolet light is preferable from the viewpoint that the polar functional group in the adhesive composition is not consumed by the reaction and high cohesive force derived from the polar component and adhesive properties can be maintained.

Examples of the crosslinking agent include crosslinking agents having at least 1 crosslinkable functional group selected from 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, a vinyl group, an amino group, an imino group, an amide group, an N-substituted (meth) acrylamide group, and an alkoxysilyl group, and 1 kind or a combination of 2 or more kinds of the crosslinking agents can be used.

The crosslinkable functional group may be protected with a protecting group capable of deprotection.

Among them, polyfunctional (meth) acrylates are preferable from the viewpoint of ease of control of the crosslinking reaction.

Examples of such polyfunctional (meth) acrylates include ultraviolet-curable polyfunctional monomers such as 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, polyalkylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, glycerol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaerythritol penta (meth) acrylate, trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, and the like, and further include: polyfunctional acrylic oligomers such as polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, and polyether (meth) acrylate, and polyfunctional acrylamides.

Examples of the crosslinking agent having 2 or more crosslinkable functional groups include: epoxy group-containing monomers such as glycidyl (meth) acrylate, glycidyl alpha-ethacrylate, 3,4-epoxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate glycidyl ether, and the like; isocyanate group-containing or blocked isocyanate group-containing monomers such as 2-isocyanatoethyl (meth) acrylate, 2- (2- (meth) acryloyloxyethyloxy) ethyl isocyanate, 2- (0- [1' -methylpropylideneamino ] carboxyamino) ethyl (meth) acrylate, and 2- [ (3,5-dimethylpyrazolyl) carbonylamino ] ethyl (meth) acrylate; various silane coupling agents such as vinyltrimethoxysilane, vinyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3- (meth) acryloyloxypropylmethyldiethoxysilane, 3- (meth) acryloyloxypropyltriethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane and 3-isocyanatopropyltriethoxysilane.

The crosslinking agent having 2 or more crosslinkable functional groups may have the following structure: a structure obtained by reacting and bonding a functional group with a (meth) acrylate (co) polymer to a (meth) acrylate (co) polymer. By adopting such a structure, a bifunctional crosslinking functional group such as a (meth) acryloyl group or a vinyl group can be chemically bonded to the (meth) acrylate (co) polymer.

Further, the crosslinking agent is bonded to the (meth) acrylate (co) polymer, and therefore bleeding of the crosslinking agent and unexpected plasticization of the adhesive sheet tend to be suppressed.

Further, since the crosslinking agent bonds to the (meth) acrylate (co) polymer and can accelerate the reaction efficiency of the photocrosslinking reaction, a cured product having a higher cohesive force tends to be obtained.

The adhesive composition may further contain a monofunctional monomer reactive with the crosslinkable functional group of the crosslinking agent. Examples of such monofunctional monomers include: alkyl (meth) acrylates such as methyl acrylate; hydroxyl group-containing (meth) acrylates such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, and polyalkylene glycol (meth) acrylate; ether group-containing (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate and methoxypolyethylene glycol (meth) acrylate; (meth) acrylamide monomers such as (meth) acrylamide, dimethyl (meth) acrylamide, diethyl (meth) acrylamide, (meth) acryloylmorpholine, isopropyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, phenyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide and N-butoxymethyl (meth) acrylamide.

Among them, hydroxyl group-containing (meth) acrylates and (meth) acrylamide monomers are preferably used from the viewpoint of improving the adhesion to an adherend and the effect of suppressing whitening due to moist heat.

The content of the crosslinking agent is preferably 0.01 to 10 parts by mass, particularly preferably 0.05 to 8 parts by mass, particularly preferably 0.1 to 5 parts by mass, based on 100 parts by mass of the (meth) acrylate (co) polymer, from the viewpoint of balancing flexibility and cohesive force of the adhesive composition.

When the adhesive sheet is a multilayer, the content of the crosslinking agent in the layers constituting the adhesive sheet, the intermediate layer, and the layer serving as a substrate may be more than the above range.

The content of the crosslinking agent in the intermediate layer and the layer to be a base material is preferably 0.01 to 40 parts by mass, particularly 1 to 30 parts by mass, and particularly preferably 2 to 25 parts by mass, based on 100 parts by mass of the (meth) acrylate (co) polymer.

(other Components)

The adhesive composition may contain other components as required in addition to the above (meth) acrylate (co) polymer, ultraviolet absorber, photoinitiator, and crosslinking agent.

Examples of the other components include: various additives such as a light stabilizer, a metal deactivator, a metal corrosion inhibitor, an anti-aging agent, an antistatic agent, a moisture absorbent, a foaming agent, an antifoaming agent, inorganic particles, a viscosity modifier, a tackifier resin, a photosensitizer, and a fluorescent agent, and a reaction catalyst (a tertiary amine compound, a quaternary ammonium compound, a tin laurate compound, and the like). In addition, known components blended in a general adhesive composition may be appropriately contained.

In addition, 2 or more of each component may be used in combination.

Among the above, the light stabilizer is particularly preferably contained.

By using a light stabilizer in combination with the ultraviolet absorber, ultraviolet resistance to foaming can be further improved. Among the above light stabilizers, a hindered amine compound (HALS) is particularly preferable.

(method for producing the adhesive composition)

The adhesive composition can be obtained by mixing a photoinitiator, an ultraviolet absorber and other components in predetermined amounts.

The mixing method in this case is not particularly limited, and the order of mixing the components is not particularly limited.

The apparatus used in the mixing is not particularly limited, and examples thereof include a universal mixer, a planetary mixer, a Banbury mixer, a kneader, a gate mixer, a pressure kneader, a three-roll mixer, and a two-roll mixer. If necessary, a solvent may be used for mixing. The adhesive composition can be used as a solvent-free system containing no solvent. By using the resin as a solvent-free system, the resin has an advantage of improving heat resistance and light resistance without leaving a solvent.

In addition, the production of the present adhesive composition may be conducted through a heat treatment step, and in the above case, it is desirable to mix the components of the present adhesive composition in advance and then perform heat treatment. The various components to be mixed may be concentrated and masterbatched.

< adhesive layer >

The adhesive sheet has an adhesive layer formed from the adhesive composition, and the adhesive layer may be completely cured, may have a curing margin, or may be in an uncured state. Among them, the pressure-sensitive adhesive layer preferably has a property of being photo-cured by light irradiation.

In addition, the pressure-sensitive adhesive layer preferably contains, as the present pressure-sensitive adhesive composition, a (meth) acrylate (co) polymer containing no carboxyl group-containing monomer in addition to the ultraviolet absorber and the photoinitiator.

In this way, the present adhesive sheet can be suitably used for bonding of a constituent member for an image display device including various conductive members such as a conductive member having a conductor pattern formed of a metal material.

< the photocurable adhesive sheet >

The present pressure-sensitive adhesive sheet has a property of being photo-cured by light irradiation, that is, a photo-curable pressure-sensitive adhesive sheet (hereinafter referred to as "the present photo-curable pressure-sensitive adhesive sheet") is capable of being photo-cured by light irradiation after being bonded to an adhesive member. The photocurable adhesive sheet can achieve both level difference absorbability when the adhesive member is adhered and foam resistance reliability after the adhesive member is adhered.

The photocurable pressure-sensitive adhesive sheet preferably has a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition containing an ultraviolet absorber having an absorption coefficient of 1X 10 at a wavelength of 340nm, a photoinitiator, and a (meth) acrylate (co) polymer containing no carboxyl group-containing monomer ³ mL/(g cm) or more and an absorption coefficient at a wavelength of 380nm of less than 1X 10 ³ mL/(g · cm), the pressure-sensitive adhesive composition contains an ultraviolet absorber in a ratio of 30 to 100 parts by mass relative to 100 parts by mass of the photoinitiator, and the pressure-sensitive adhesive layer has a property of being photo-cured by light irradiation.

The photocurable pressure-sensitive adhesive sheet may be cured (also referred to as "precure") with a room for photocuring, or may not be precured at all.

In the above case, the gel fraction of the photocurable pressure-sensitive adhesive sheet without precuring at all is preferably 5% or less.

On the other hand, the gel fraction of the photocurable pressure-sensitive adhesive sheet after precuring is preferably 80% or less, more preferably 5% or more or 70% or less, particularly 10% or more or 60% or less.

The gel fraction of the photocurable pressure-sensitive adhesive sheet after final photocuring (simply referred to as "photocuring" or "main curing") is preferably 30% or more, particularly preferably 40% or more, and particularly preferably 50% or more. By photocuring the photocurable adhesive sheet in such a range, the photocurable adhesive sheet can have a high cohesive force even in a severe high-temperature and high-humidity environment, and the foaming resistance reliability can be improved.

As a preferred method for forming the pressure-sensitive adhesive layer included in the photocurable pressure-sensitive adhesive sheet, the following (1) or (2) can be mentioned.

(1) In the production of the photocurable adhesive sheet, the sheet shape is maintained in a precured (1-time crosslinking) state, and a pressure-sensitive adhesive layer having a photocurable (photoactive) state is formed.

(2) In the production of the photocurable adhesive sheet, the adhesive layer is formed in a state of photocurability (photoactivity) while maintaining the sheet shape in an uncured (crosslinked) state.

Specific examples of the above (1) include a method of forming an adhesive layer by heating or curing a composition (adhesive) containing: a photopolymerization initiator; (meth) acrylate (co) polymers having functional group (i); a compound having a functional group (ii) reactive with the functional group (i); and, further, a polyfunctional (meth) acrylate having 2 or more (meth) acryloyl groups as necessary.

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 curing (crosslinking) to form an adhesive layer. The adhesive layer is formed such that the photopolymerization initiator can be present in the adhesive layer with activity.

In this case, as the photopolymerization initiator, the above-mentioned cleavage type photoinitiator and hydrogen abstraction type photoinitiator may be used.

The combination of the functional group (i) and the functional group (ii) is preferably, 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. Among them, a combination of a hydroxyl group (functional group (i)) and an isocyanate group (functional group (ii)) or an amino group (functional group (i)) and an isocyanate group (functional group (ii)) is particularly preferable. More specifically, the (meth) acrylate copolymer having a hydroxyl group is particularly suitable when a (meth) acrylate copolymer is used as a copolymer containing a monomer component of the hydroxyl group-containing monomer (copolymerizable monomer D), and the compound has an isocyanate group.

The compound having the functional group (ii) may further have a radical polymerizable functional group such as a (meth) acryloyl group. This makes it possible to form the pressure-sensitive adhesive layer while maintaining the photocurability (crosslinking) of the (meth) acrylate (co) polymer having a radical polymerizable functional group. More specifically, when the (meth) acrylate (co) polymer has a hydroxyl group, for example, a (meth) acrylate copolymer which is a copolymer of monomer components including the hydroxyl group-containing monomer is used, and the compound has a (meth) acryloyl group, for example, a case where the compound is 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, 1,1- (bisacryloxymethyl) ethyl isocyanate, or the like is particularly suitable.

In this way, by utilizing the crosslinking reaction between the (meth) acrylate (co) polymers based on the radical polymerizable functional group, even if a polyfunctional (meth) acrylate having 2 or more (meth) acryloyl groups is not used, the cohesive force after photocuring (crosslinking) is easily and efficiently improved, and there are advantages such as excellent reliability, and the like, and therefore, more preferable is the case.

As another specific example of the above (1), there can be mentioned, for example, a method using the above hydrogen abstraction type initiator as a photopolymerization initiator. The hydrogen abstraction initiator is returned to the ground state even when it is excited once, and therefore, it can be reused as a photopolymerization initiator. By using the hydrogen abstraction photoinitiator in this manner, photocurability (crosslinking) by the photopolymerization initiator can be maintained even after the production of the adhesive sheet.

Specific examples of (2) include: a method of using the above-mentioned macromonomer as a monomer component constituting the (meth) acrylate copolymer. More specifically, there may be mentioned: a method of using a graft copolymer having a macromonomer as a branch component. By using such a macromonomer, the branch components attract each other at room temperature, and the physically crosslinked state as a composition (binder) can be maintained.

Therefore, the sheet state can be maintained without curing (crosslinking), and an adhesive sheet having an adhesive layer containing a photoinitiator that generates radicals if receiving light can be produced. In this case, the above-mentioned cleavage type photoinitiator and hydrogen abstraction type photoinitiator may be used as the photopolymerization initiator.

The photocurable pressure-sensitive adhesive sheet preferably has the following spectroscopic characteristics.

That is, the light transmittance at a wavelength of 320nm of the photocurable adhesive sheet is preferably 10% or less, more preferably 5% or less, and still more preferably 3% or less. The light transmittance at a wavelength of 340nm is preferably 20% or less, more preferably 10% or less, and still more preferably 5% or less.

By having the above light transmittance, the occurrence of foaming, peeling, and the like associated with deterioration of the pressure-sensitive adhesive sheet itself can be suppressed.

The light transmittance of the present photocurable pressure-sensitive adhesive sheet at a wavelength of 365nm is preferably 10% or more, more preferably 15% or more or 90% or less, and still more preferably 20% or more and 80% or less.

The light transmittance of the present photocurable pressure-sensitive adhesive sheet at a wavelength of 380nm is preferably 20% or more, more preferably 30% or more or 95% or less, and still more preferably 40% or more and 90% or less.

The light transmittance of the present photocurable pressure-sensitive adhesive sheet at a wavelength of 395nm is preferably 50% or more, more preferably 70% or more, and still more preferably 80% or more.

By having the light transmittance, the photoinitiator is easily activated, and therefore, the cohesive force of the adhesive after photocuring can be sufficiently obtained, and reliability can be easily obtained.

The present photocurable pressure-sensitive adhesive sheet may be suitably selected and applied in the same manner as the present pressure-sensitive adhesive sheet described above, and a preferred embodiment of the present pressure-sensitive adhesive sheet and a preferred embodiment of the present photocurable pressure-sensitive adhesive sheet may be replaced with each other.

(Metal corrosion inhibitor)

Therefore, when the photocurable pressure-sensitive adhesive sheet is formed from the pressure-sensitive adhesive composition containing as a main component a (co) polymer containing no monomer component containing a carboxyl group-containing monomer, the sheet has excellent corrosion resistance to metals.

However, as a result of studies on corrosion of a metal material when a photocurable adhesive sheet is attached to a conductive member formed of a specific metal, for example, a metal material containing silver and photocured, it has been found that a photoinitiator contained in the adhesive sheet is activated by light to generate radicals, and the radicals react with silver in the metal material, so that corrosion of the metal material containing silver may proceed.

In order to solve the above problems, the following proposals are made: the photocurable pressure-sensitive adhesive sheet contains a metal corrosion inhibitor and forms a protective film on the silver of the conductive member, thereby inhibiting the reaction of radicals generated by the photoinitiator by the irradiation with light with the silver of the conductive member.

From the above viewpoint, the photocurable pressure-sensitive adhesive sheet preferably has a pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition containing a metal corrosion inhibitor.

In the present binder composition, the metal corrosion inhibitor is preferably contained in a proportion of 0.05 to 2.0 mass% with respect to the total mass of the present binder composition.

In the adhesive composition, the metal corrosion inhibitor is preferably contained in a proportion of 10 to 200 parts by mass with respect to 100 parts by weight of the photoinitiator.

By containing the metal compound at such a ratio, the effect of the metal corrosion inhibitor can be exhibited to the maximum extent without inhibiting the curing by the photoinitiator.

From such a viewpoint, the metal corrosion inhibitor is preferably contained in a ratio of 10 to 200 parts by mass, more preferably 12 parts by mass or more or 80 parts by mass or less, further preferably 15 parts by mass or more or 70 parts by mass or less, and further preferably 20 parts by mass or more or 50 parts by mass or less, based on 100 parts by mass of the photoinitiator.

The metal corrosion inhibitor is preferably used in such a manner that the photoreaction of the adhesive composition is not inhibited by the metal corrosion inhibitor contained therein, and the absorption coefficient at 365nm is particularly preferably 20 mL/(g cm) or less, particularly 10 mL/(g cm) or less, particularly 5 mL/(g cm) or less, particularly 1 mL/(g cm) or less.

As the metal corrosion inhibitor having such characteristics, a metal corrosion inhibitor not contained in any of a naphthalene skeleton, an anthracene skeleton, a thiazole skeleton, and a thiadiazole skeleton is preferable. The metal corrosion inhibitor does not have such a skeleton and thus may have an absorption coefficient in the above range.

In addition, the metal corrosion inhibitor is preferably a hydrophilic compound.

Since the metal corrosion inhibitor is easily moved in the pressure-sensitive adhesive layer using a (meth) acrylic (co) polymer as a base resin, which is also hydrophilic, if it is hydrophilic, it can form a protective coating by chemically bonding with, for example, silver atoms, and can suppress attack (reaction) of radicals generated from a photoinitiator by light irradiation on a metal member, particularly silver.

From the above-mentioned viewpoint, the water solubility of the metal corrosion inhibitor at 25 ℃ is preferably 20g/L or more, particularly preferably 50g/L or more, particularly 100g/L or more.

From the above-mentioned viewpoints, as the metal corrosion inhibitor, a triazole-based compound is preferable among metal corrosion inhibitors having an absorption coefficient of 365nm of 20 mL/(g · cm) or less and comprising a hydrophilic compound, and a mixture of 1 or 2 or more selected from benzotriazole, 1,2,3-triazole and 1,2,4-triazole is particularly preferable among them.

The benzotriazole may be any substituted or unsubstituted benzotriazole, and examples thereof include alkylbenzotriazoles such as 1,2,3-benzotriazole and methyl-1H-benzotriazole, carboxybenzotriazole, 1-hydroxybenzotriazole, 5-aminobenzotriazole, 5-phenylmercaptobenzotriazole, 5-methoxybenzotriazole, nitrobenzotriazole, chlorobenzotriazole, bromobenzotriazole and fluorobenzotriazole, halogenated benzotriazoles such as copper benzotriazole, silver benzotriazole and benzotriazole silane compounds. Among them, from the viewpoint of dispersibility in the adhesive composition, ease of addition, and effect of preventing metal corrosion, it is preferable to use any 1 or 2 or more selected from the group consisting of 1,2,3-benzotriazole, 1- [ N, N-bis (2-ethylhexyl) aminomethyl ] methylbenzotriazole, and 2,2' - [ [ (methyl-1H-benzotriazol-1-yl) methyl ] imino ] diethanol.

Furthermore, 1,2,4-triazole is a solid with a melting point of about 120 ℃, while 1,2,3-triazole has a melting point of about 20 ℃ and is substantially liquid at room temperature. Thus, 1,2,3-triazole is excellent in dispersibility when mixed in an adhesive composition, can be uniformly mixed, and is easy to master batch.

< physical Properties of the pressure-sensitive adhesive sheet >

The present adhesive sheet is preferably optically transparent. That is, a transparent adhesive sheet is preferable. Here, "optically transparent" means that the total light transmittance is intended to be 80% or more, preferably 85% or more, more preferably 90% or more.

< use form of the pressure-sensitive adhesive sheet >

The pressure-sensitive adhesive sheet can be used by directly applying the pressure-sensitive adhesive composition to an adherend to form a sheet, or can be formed into a single-layer or multi-layer sheet-like pressure-sensitive adhesive sheet with a release film on a release film. That is, a release film sheet-equipped psa sheet can be formed by laminating a release film on at least the front and back sides of the psa sheet.

Examples of the material of the release film include a polyester film, a polyolefin film, a polycarbonate film, a polystyrene film, an acrylic film, a cellulose triacetate film, and a fluororesin film. Among them, polyester films and polyolefin films are particularly preferable.

The light transmittance of the release film for light having a wavelength of 410nm or less is preferably 40% or less.

By laminating a release film having a light transmittance of 40% or less at a wavelength of 410nm or less on at least one surface of the adhesive sheet, photopolymerization by irradiation with visible light can be effectively prevented even when a photoinitiator active in the visible light wavelength range is used.

From the above-described viewpoint, the light transmittance of light having a wavelength of 410nm or less is preferably 40% or less, more preferably 30% or less, particularly 20% or less, with respect to the release film laminated on one or both surfaces of the present adhesive sheet.

Here, examples of the release film having a light transmittance of light having a wavelength of 410nm or less of 40% or less, that is, a film having an effect of shielding transmission of part of visible light and ultraviolet light include: a laminated film having an ultraviolet absorbing layer, which is formed by coating a releasable micro-adhesive resin on one surface of a polyester, polypropylene or polyethylene cast film or a stretched film and coating a coating material containing an ultraviolet absorber on the other surface.

In addition, there may be mentioned: a removable micro-adhesive resin mixed with an ultraviolet absorber is coated on one surface of a polypropylene-based, polyethylene-based cast film or a stretched film.

In addition, there may be mentioned: and a method for producing the same, wherein a slightly adhesive resin having removability is applied to a casting film or a stretched film made of a polyester, polypropylene or polyethylene resin containing an ultraviolet absorber.

In addition, there may be mentioned: and a multilayer cast film or a multilayer stretched film formed by molding a layer made of a resin not containing an ultraviolet absorber on one or both surfaces of a layer made of a polyester, polypropylene or polyethylene resin containing an ultraviolet absorber, and coating a releasable micro adhesive resin on one surface of the obtained multilayer cast film or stretched film.

In addition, there may be mentioned: an ultraviolet absorbing layer is formed by coating one surface of a casting film or a stretched film made of polyester, polypropylene or polyethylene resins with a coating containing an ultraviolet absorber, and a micro-adhesive resin having removability is further coated on the ultraviolet absorbing layer.

In addition, there may be mentioned: the ultraviolet absorbing layer is formed by coating one surface of a casting film or a stretched film made of polyester, polypropylene or polyethylene resins with a coating containing an ultraviolet absorber, and the other surface is coated with a removable micro-adhesive resin. In addition, there may be mentioned: and a resin film formed by coating a polyester, polypropylene or polyethylene resin having a removable micro adhesive resin on one surface thereof, and a separately prepared resin film laminated on the other surface thereof via an adhesive layer or a pressure-sensitive adhesive layer containing an ultraviolet absorber.

The film may have an antistatic layer, a hard coat layer, an anchor layer, and the like, as other layers as necessary.

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

The present pressure-sensitive adhesive sheet may be produced by the following method using an adherend or a release film, as described above: a method of directly extruding the adhesive composition and a method of injecting the adhesive composition into a mold to form the adhesive composition. Further, the adhesive composition can be directly filled between members such as a conductive member to form an adhesive sheet.

< uses of the adhesive sheet >

The adhesive sheet is suitable for bonding constituent members for image display devices, such as personal computers, mobile terminals (PDAs), game machines, televisions (TVs), car navigation system gate systems, touch panels, and image display devices using image display panels, such as Plasma Displays (PDPs), liquid Crystal Displays (LCDs), organic EL displays (OLEDs), inorganic EL displays, electrophoretic displays (EPDs), and interferometric modulation displays (IMODs).

Among them, a conductive member having a transparent conductive layer formed of a metal material containing silver is suitable for lamination. At this time, the aforementioned conductive member may have an insulating protective film (passivation film).

The present adhesive sheet can be used by being bonded to a conductive layer surface provided with a conductive member made of a metal material containing silver, for example, a transparent conductive layer.

In this case, the adhesive sheet may have a structure in which any one of the adhesive layer surfaces and the conductive layer surface of the transparent conductive layer are bonded.

When the present pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet, the laminate may have a structure in which two pressure-sensitive adhesive layer surfaces of the present pressure-sensitive adhesive sheet and a conductive layer surface of the transparent conductive layer are bonded to each other.

< laminate for constituting image display device >

The adhesive sheet can be bonded to 1 or more image display device constituent members to form a laminate for image display device constituent. Among these, the laminate for constituting an image display device (referred to as "laminate for constituting an image display device") is preferably formed by laminating a constituent member for an image display device including a conductive member formed of a metal material containing silver and another constituent member for an image display device via the present adhesive sheet.

When the laminate for image display device construction is produced using the photocurable adhesive sheet, the laminate for image display device construction can be produced by laminating the 2 image display device constituent members via the photocurable adhesive sheet, and then irradiating light from at least one image display device constituent member side to photocure the photocurable adhesive sheet.

Specific examples of the laminate for constituting the image display device include: a release film/the present adhesive sheet/a touch panel, an image display panel/the present adhesive sheet/the touch panel/the present adhesive sheet/a protective panel, a polarizing film/the present adhesive sheet/the touch panel/the present adhesive sheet/the protective panel, and the like.

Further, the touch panel includes: the protective panel incorporates a structure having a touch panel function, and the image display panel incorporates a structure having a touch panel function.

Therefore, the laminate for constituting the image display device may be, for example, a release film, an adhesive sheet, a protective panel, a release film, an adhesive sheet, an image display panel, an adhesive sheet, a protective panel, or the like.

In addition, the above configuration includes: the conductive layer is interposed between the adhesive sheet and members adjacent thereto, such as a touch panel, a protective panel, an image display panel, and a polarizing film. However, the present invention is not limited to these examples.

The touch panel may be of a resistive film type, a capacitive type, an electromagnetic induction type, or the like. Among them, the electrostatic capacitance system is preferable.

The surface protective panel may be made of, in addition to glass, plastic such as alicyclic polyolefin resin such as acrylic resin, polycarbonate resin, or cycloolefin polymer, styrene resin, polyvinyl chloride resin, phenol resin, melamine resin, or epoxy resin.

The surface protective panel may be made of, in addition to glass, plastic such as alicyclic polyolefin resin such as acrylic resin, polycarbonate resin, or cycloolefin polymer, styrene resin, polyvinyl chloride resin, phenol resin, melamine resin, or epoxy resin.

The image display panel is composed of a polarizing film, another optical film such as a retardation film, a liquid crystal material, and a backlight system (generally, the surface of the adhesive composition or the adhesive article to be bonded to the image display panel is an optical film), and the control method of the liquid crystal material includes an STN method, a VA method, an IPS method, and the like, and any method is possible.

The laminate for constituting an image display device can be used as a constituent member of an image display device such as a liquid crystal display, an organic EL display, an inorganic EL display, an electronic paper, a plasma display, and a Micro Electro Mechanical System (MEMS) display.

The image display panel is composed of a polarizing film, another optical film such as a retardation film, a liquid crystal material, and a backlight system (generally, the surface of the adhesive composition or the adhesive article to be bonded to the image display panel is an optical film), and the control method of the liquid crystal material includes an STN method, a VA method, an IPS method, and the like, and any method is possible.

< description of terms >

In the present specification, when "X to Y" (X, Y is an arbitrary number), the meaning of "X or more and Y or less" is included, and the meaning of "preferably more than X" or "preferably less than Y" is also included, unless otherwise specified.

In addition, when the expression "X or more" (X is an arbitrary number) or "Y or less" (Y is an arbitrary number), the meaning of "preferably more than X" or "preferably less than Y" is also included.

Examples

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following examples.

< example 1>

A graft copolymer (A-1, mass average molecular weight 30 ten thousand, tg-12 ℃) comprising 15 parts by mass of a macromonomer (number average molecular weight 2500) comprising methyl methacrylate as a branched component and 81 parts by mass of n-butyl acrylate as a dry component per 4 parts by mass of acrylic acid as a (meth) acrylate (co) polymer (a), 1kg of 2-hydroxy-4-n-octyloxybenzophenone (B-1, molecular weight 326.4, melting point 48 ℃) as an ultraviolet absorber (B), 5g of a mixture (C-1) of 2,4,6-trimethylbenzophenone and 4-methylbenzophenone as a photoinitiator (C), 100g of propoxylated pentaerythritol triacrylate (D-1) as a crosslinking agent (D), 2,2,6,6-tetramethyl-1-octyloxy-4-piperidin-4-yl) (E-1) 2g as a light-resistant stabilizer (E), 3425 zxft (3425-triazole (F-1) as a metal (F) as an anticorrosive (F) were uniformly melted and kneaded to prepare a corrosion inhibitor (a resin composition.

The metal corrosion inhibitor 1,2,3-triazole (F-1) has an absorption coefficient of 0.3 mL/(g cm) at 365nm and a water solubility of >1000g/L at 25 ℃.

This resin composition 1 was sandwiched by 2 peeled polyethylene terephthalate films ("DIAFOIL MRF" manufactured by Mitsubishi chemical corporation, thickness 75 μm/DIAFOIL MRT "manufactured by Mitsubishi chemical corporation, thickness 38 μm), and formed into a sheet shape at 80 ℃ so that the thickness became 100 μm, to prepare a transparent double-sided adhesive sheet 1.

The pressure-sensitive adhesive layer in the transparent double-sided pressure-sensitive adhesive sheet 1 is in an uncured state and has a property of being photo-cured by light irradiation.

< example 2>

The branched component of the (meth) acrylate (co) polymer (a) is isobornyl methacrylate: methyl methacrylate =1: 1.5 parts by mass of a macromonomer (number average molecular weight 3000), 1kg of a copolymer (A-2 having a mass average molecular weight of 16 ten thousand) comprising 43.7 parts by mass of lauryl acrylate/40 parts by mass of 2-ethylhexyl acrylate/2.8 parts by mass of acrylamide as a dry component, (B-1) 5g of an ultraviolet absorber (B), 10g of a photoinitiator (C), (D-1) 100g of a crosslinking agent (D), and (E-1) 2g of a light-resistant stabilizer (E) were uniformly melt-kneaded to prepare a resin composition 2.

This resin composition 2 was sandwiched by 2 polyethylene terephthalate films (DIAFOIL MRF, thickness 75 μm/DIAFOIL MRT, thickness 38 μm, manufactured by Mitsubishi chemical corporation) which had been subjected to a peeling treatment, and was formed into a sheet shape at a temperature of 80 ℃ so that the thickness became 100 μm, thereby producing a transparent double-sided adhesive sheet 2.

The pressure-sensitive adhesive layer in the transparent double-sided pressure-sensitive adhesive sheet 2 is in an uncured state and has a property of being photo-cured by light irradiation.

< example 3>

1kg of a copolymer (A-3) comprising 55 parts by mass of 2-ethylhexyl acrylate/20 parts by mass of vinyl acetate/5 parts by mass of acrylic acid as a (meth) acrylate (co) polymer (a), 5g of (B-1) as an ultraviolet absorber (B), 8g of (C-1) as a photoinitiator (C), 30g of (D-1) as a crosslinking agent (D), and 2g of (E-1) as a light stabilizer (E) were uniformly melt-kneaded to prepare a resin composition 3.

The resin composition 3 was sandwiched by 2 polyethylene terephthalate films (DIAFOIL MRF manufactured by Mitsubishi chemical corporation, thickness 75 μm/DIAFOIL MRT manufactured by Mitsubishi chemical corporation, thickness 38 μm) which had been subjected to a peeling treatment, and the resin composition was formed into a sheet shape at a temperature of 60 ℃ so that the thickness became 100 μm, and the cumulative light amount at a wavelength of 365nm became 1500mJ/cm from one side of the polyethylene terephthalate film ² The transparent double-sided adhesive sheet 3 was prepared by irradiating light with a high-pressure mercury lamp to precure the sheet.

The pressure-sensitive adhesive layer in the transparent double-sided pressure-sensitive adhesive sheet 3 leaves room for photocuring by light irradiation.

< example 4>

1kg of (A-2) as a (meth) acrylate (co) polymer (a), 5g of (B-1) as an ultraviolet absorber (B), 10g of (C-1) as a photoinitiator (C), 100g of (D-1) as a crosslinking agent (D), and 2g of (F-1) as a metal corrosion inhibitor (F) were uniformly melt-kneaded to prepare a resin composition 4.

This resin composition 4 was sandwiched by 2 polyethylene terephthalate films (DIAFOIL MRF, thickness 75 μm/DIAFOIL MRT, thickness 38 μm, manufactured by Mitsubishi chemical corporation) which had been subjected to a peeling treatment, and was formed into a sheet shape at a temperature of 80 ℃ so that the thickness became 100 μm, thereby producing a transparent double-sided adhesive sheet 4.

The pressure-sensitive adhesive layer in the transparent double-sided pressure-sensitive adhesive sheet 4 is in an uncured state and has a property of being photo-cured by light irradiation.

< example 5>

1kg of (A-2) as a (meth) acrylate (co) polymer (a), 8g of (B-1) as an ultraviolet absorber (B), 8g of (C-1) as a photoinitiator (C), and 100g of (D-1) as a crosslinking agent (D) were uniformly melt-kneaded to prepare a resin composition 5.

This resin composition 5 was sandwiched by 2 polyethylene terephthalate films (DIAFOIL MRF, thickness 75 μm/DIAFOIL MRT, thickness 38 μm, manufactured by Mitsubishi chemical corporation) which had been subjected to a peeling treatment, and was formed into a sheet shape at a temperature of 80 ℃ so that the thickness became 100 μm, thereby producing a transparent double-sided adhesive sheet 5.

The pressure-sensitive adhesive layer in the transparent double-sided pressure-sensitive adhesive sheet 5 is in an uncured state and has a property of being photo-cured by light irradiation.

< example 6>

1kg of (A-2) as a (meth) acrylate (co) polymer (a), 8g of (B-1) as an ultraviolet absorber (B), 8g of a mixture (C-2) of 50 parts by weight of (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) acetone) oligomer as a photoinitiator (C), 46 parts by weight of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide/2,4,6-trimethylbenzophenone, 3.2 parts by weight of 4-methylbenzophenone and 0.8 part by weight of (D-1) as a crosslinking agent (D) were uniformly melt-kneaded to prepare a resin composition 6.

This resin composition 6 was sandwiched by 2 polyethylene terephthalate films (DIAFOIL MRF, thickness 75 μm/DIAFOIL MRT, thickness 38 μm, manufactured by Mitsubishi chemical corporation) which had been subjected to a peeling treatment, and was formed into a sheet shape at a temperature of 80 ℃ so that the thickness became 100 μm, thereby producing a transparent double-sided adhesive sheet 6.

The pressure-sensitive adhesive layer in the transparent double-sided pressure-sensitive adhesive sheet 6 is in an uncured state and has a property of being photo-cured by light irradiation.

< example 7>

1kg of (A-1) as a (meth) acrylate (co) polymer (a), 18g of (B-1) as an ultraviolet absorber (B), 20g of (C-1) as a photoinitiator (C), and 120g of (D-1) as a crosslinking agent (D) were uniformly melt-kneaded to prepare a resin composition 7.

This resin composition 7 was sandwiched by 2 polyethylene terephthalate films (DIAFOIL MRF, thickness 75 μm/DIAFOIL MRT, thickness 38 μm, manufactured by Mitsubishi chemical corporation) which had been subjected to a peeling treatment, and was formed into a sheet shape at a temperature of 80 ℃ so that the thickness became 100 μm, thereby producing a transparent double-sided adhesive sheet 7.

The pressure-sensitive adhesive layer in the transparent double-sided pressure-sensitive adhesive sheet 7 is in an uncured state and has a property of being photo-cured by light irradiation.

< comparative example 1>

1kg of (A-2) as a (meth) acrylate (co) polymer (a), 5g of 2,2-dihydroxy-4-methoxybenzophenone (B-2, molecular weight 244.2, melting point 73 ℃ C.) as an ultraviolet absorber (B), 10g of (C-1) as a photoinitiator (C), 100g of (D-1) as a crosslinking agent (D), and 2g of (E-1) as a light-resistant stabilizer (E) were uniformly melt-kneaded to prepare a resin composition 8.

This resin composition 8 was sandwiched by 2 polyethylene terephthalate films (DIAFOIL MRF, thickness 75 μm/DIAFOIL MRT, thickness 38 μm, manufactured by Mitsubishi chemical corporation) which had been subjected to a peeling treatment, and was formed into a sheet shape at a temperature of 80 ℃ so that the thickness became 100 μm, thereby producing a transparent double-sided adhesive sheet 8.

The pressure-sensitive adhesive layer in the transparent double-sided pressure-sensitive adhesive sheet 8 is in an uncured state and has a property of being photo-cured by light irradiation.

< comparative example 2>

1kg of (A-1) as a (meth) acrylate (co) polymer (a), 20g of (B-1) as an ultraviolet absorber (B), 15g of (C-1) as a photoinitiator (C), and 100g of (D-1) as a crosslinking agent (D) were uniformly melt-kneaded to prepare a resin composition 9.

This resin composition 9 was sandwiched by 2 polyethylene terephthalate films (DIAFOIL MRF, thickness 75 μm/DIAFOIL MRT, thickness 38 μm, manufactured by Mitsubishi chemical corporation) which had been subjected to a peeling treatment, and was formed into a sheet shape at a temperature of 80 ℃ so that the thickness became 100 μm, thereby producing a transparent double-sided adhesive sheet 9.

The pressure-sensitive adhesive layer in the transparent double-sided pressure-sensitive adhesive sheet 9 is in an uncured state and has a property of being photo-cured by light irradiation.

< comparative example 3>

1kg of (A-3) as a (meth) acrylate (co) polymer (a), 8g of (C-1) as a photoinitiator (C), and 30g of (D-1) as a crosslinking agent (D) were uniformly melt-kneaded to prepare a resin composition 10. No ultraviolet absorber (b) was added.

The resin composition 10 was sandwiched by 2 polyethylene terephthalate films (DIAFOIL MRF, thickness 75 μm/DIAFOIL MRT, thickness 38 μm, manufactured by Mitsubishi chemical corporation) which had been subjected to a peeling treatment, and was formed into a sheet shape at a temperature of 60 ℃ so that the thickness became 100 μm, and the cumulative light amount at a wavelength of 365nm became 1000mJ/cm from one side of the polyethylene terephthalate film ² The transparent double-sided adhesive sheet 10 was prepared by irradiating light with a high-pressure mercury lamp to precure the sheet.

The pressure-sensitive adhesive layer in the transparent double-sided pressure-sensitive adhesive sheet 10 has a room for photo-curing by light irradiation.

[ evaluation of physical Properties ]

The physical properties of the transparent double-sided pressure-sensitive adhesive sheets obtained in examples/comparative examples were measured as follows.

< gel fraction >

The release films of the transparent double-sided adhesive sheets 1 to 10 were peeled off from each other on both sides, and about 0.4g of each of the transparent double-sided adhesive sheets 1 to 10 was collected, and the resultant was wrapped in a bag shape with an SUS sieve (# 200) whose mass (X) was measured in advance, and the bag mouth was folded and sealed, and the mass (Y) of the bag was measured. Thereafter, the packet was immersed in 50mL of ethyl acetate for 24 hours, taken out, vacuum-dried at 70 ℃ for 4.5 hours to evaporate the adhered ethyl acetate, and the mass (Z) of the dried packet was measured and the mass thus obtained was substituted into the following formula.

Gel fraction [% ] = [ (Z-X)/(Y-X) ]. Times.100

The transparent double-sided adhesive sheets 1 to 10 were directly used as measurement samples before photocuring (main curing). As for the measurement sample after photocuring (main curing), the following were set as measurement samples: the transparent double-sided adhesive sheets 1 to 10 were passed through a release film and were irradiated with a high-pressure mercury lamp at a cumulative light amount of 365nm of 3000mJ/cm ² The method (4) is performed by irradiating light, and then aging is performed at room temperature for 12 hours.

< spectroscopic characteristics >

The transparent double-sided adhesive sheets 1 to 10 were cut into 50 × 80mm with a thomson punch while maintaining the state in which the release film was laminated. One side of the release film was peeled off, and the exposed adhesive surface was bonded to soda-lime glass (54X 82mm, t0.6mm) with a hand roller. Thereafter, the glass was pressed and bonded to another 1 sheet of soda-lime glass (same as above) under vacuum (pressing pressure 0.1MPa at 23 ℃ for 1 minute). Then, the glass was subjected to autoclave treatment (60 ℃ C., gauge pressure 0.2MPa, 20 minutes) to effect processing and bonding, and a high-pressure mercury lamp was used from one glass side to obtain a cumulative light amount at 365nm of 3000mJ/cm ² The adhesive sheet was cured by light irradiation and aged at room temperature for 12 hours to prepare a sample for spectroscopic characteristic measurement. Using these, the spectroscopic properties of the transparent double-sided adhesive sheets 1 to 10 were measured under the following conditions.

< device > UV-2450 (manufactured by Shimadzu corporation)

< wavelength > 300-400 nm (light transmittance at measurement wavelengths 320nm, 340nm, 365nm, 380nm, 395 nm)

< storage stability >

The transparent double-sided adhesive sheets 1 to 10 were cut into 50 × 50mm with a thomson punch while maintaining the state in which the release film was laminated. These adhesive sheets were left to stand with the DIAFOIL MRT (release film) on the upper side, and irradiated with light of an illuminance of 1100Lx for 24 hours by a 3-wavelength fluorescent lamp, and the gel fraction before and after irradiation was measured by the above-mentioned method, thereby calculating the change in gel fraction before and after a storage test under a strong fluorescent lamp.

Then, storage stability was determined by the following criteria.

After the test, the adhesive sheet was judged to have a significantly increased gel fraction, a change in gel fraction of 20% or more as "x (pore)", a change in gel fraction of 10% or more but less than 20% as "good", and a change in gel fraction of less than 10% as "very good".

< Heat resistant foamability >

The transparent double-sided adhesive sheets 1 to 10 were cut into 50 × 80mm with a thomson punch while maintaining the state in which the release film was laminated. One side of the release film was peeled off, and the exposed adhesive surface was bonded to soda-lime glass 1 (54X 82mm, t0.6mm) with a hand roller. Next, the release film on the adhesive side of the polarizing plate (VLC 2 manufactured by Sanritz co., ltd) with adhesive was peeled off, and the exposed adhesive surface was bonded to soda-lime glass 2 (54 × 82mm, t0.6 mm) with a hand roller. Further, the protective film on the polarizing plate side was peeled off, and 6 glass beads (diameter: 40 μm) were arranged on the polarizing plate. On the polarizing plate side, the other release film of the transparent double-sided adhesive sheets 1 to 10 attached to the soda-lime glass 1 was peeled off, and was bonded to the polarizing plate on which glass beads were arranged by a hand roller.

Then, the resultant was subjected to autoclave treatment (60 ℃ C., gauge pressure 0.2MPa, 20 minutes) to effect processing and bonding, and the cumulative light amount at 365nm from the soda-lime glass 1 side was 3000mJ/cm using a high-pressure mercury lamp ² The adhesive sheet was cured by light irradiation and aged at room temperature for 12 hours to prepare a sample for evaluating thermal expansion resistance (soda lime glass 1/transparent double-sided adhesive sheet/polarizing plate with adhesive/soda lime glass 2).

They were left standing at 85 ℃ for 300 hours, and the presence or absence of foaming was visually observed.

The one with bubbles at the interface between the polarizing plate and the transparent double-sided adhesive sheet was judged as "x (hole)", and the one with no bubbles and good appearance was judged as "good".

< ultraviolet ray resistance to foaming >

The transparent double-sided adhesive sheets 1 to 10 were cut into 200 × 150mm with a thomson punch while maintaining the state in which the release film was laminated. Of a transparent double-sided adhesive sheetThe release film was peeled off, and the exposed adhesive surface was bonded to the entire surface of soda-lime glass (200X 150mm, t0.6mm) by a hand roller. Then, the other release film was peeled off, and the exposed adhesive surface was pressure-bonded to another 1-sheet soda-lime glass (200X 150mm, t0.6 mm) by vacuum pressing (23 ℃ C., pressing pressure 0.1MPa, 1 minute). Then, the glass was subjected to autoclave treatment (60 ℃ C., gauge pressure 0.2MPa, 20 minutes) to effect processing and bonding, and a high-pressure mercury lamp was used from one glass side to obtain a cumulative light amount at 365nm of 3000mJ/cm ² The adhesive sheet was cured by light irradiation and aged at room temperature for 12 hours to prepare a sample for evaluation of UV foaming resistance.

These were left to stand for 8 hours/24 hours in the following environment, and the presence or absence of foaming or fine bubbles in the strong UV irradiation environment was visually observed over time.

< device > Suntest CPS + (manufactured by Toyo Seiki Seiko Co., ltd.)

< light source > xenon arc lamp (air cooling type, wavelength 270nm cut-off filter)

< illuminance by radiation>765W/m ² (wavelength 800nm or less)

(temperature > BST63℃)

Then, the ultraviolet ray foamability resistance was judged by the following criteria.

The case where a large amount of large foams or fine cells were generated after 3 hours of standing was judged as "x (pore)", the case where the appearance was good after 3 hours of standing and the foams or fine cells were generated after 8 hours of standing was judged as "Δ (usual)", the case where the appearance was good after 8 hours of standing and the foams or fine cells were generated after 24 hours of standing was judged as "good" (good) ", and the case where the appearance was good after 24 hours was judged as" excellent "(very good)".

< resistance to silver Corrosion >

As a conductive member containing silver, a silver nanowire film (ActivegRIdFilm manufactured by C3nano, polyethylene terephthalate (thickness 50 μm) was prepared as a substrate, surface resistance value 50. Omega./□, protective layer-attached total light transmittance of 91%, haze of 0.9% or less, b.ang. Or less 1.3) was prepared.

As shown in FIG. 1, a silver nanowire film was cut into a length of 45X a width of 80mm, a silver paste (dot D-550 manufactured by Kabushiki Kaisha) was applied in the length direction to a width of about 3 to 5mm so that the width between the electrodes became 50mm, and after drying, the silver nanowire film was cut into a width of 9mm in the width direction. The 9mm × 80mm × 5 silver nanowire films with silver paste electrodes were arranged in parallel on soda-lime glass.

On the adhesive sheet, a 50mm wide double-sided adhesive sheet was cut, the single-sided release film was peeled off, the adhesive sheet was bonded with a roll so that the adhesive sheet was positioned between electrodes, autoclave treatment (60 ℃ C., gauge pressure 0.2MPa, 20 minutes) was performed, the adhesive sheet was processed and attached, and light was irradiated from the adhesive sheet side with the release film with a high-pressure mercury lamp and photocured so that the cumulative light amount at a wavelength of 365nm became 3000mJ/cm ² 。

The samples were subjected to an environmental test in a hot and humid environment of 65 ℃ 90% RH X300 h, and the increase in the resistance value between the electrodes was confirmed.

In the above-described environmental test, a case in which the resistance value increase exceeds 10% is determined as "Δ (usual)", a case in which the resistance value increase is suppressed to 10% or less is determined as "o (good)", and a case in which the resistance value increase is suppressed to 1% or less is determined as "excellent (very good)".

The evaluation results of the examples and comparative examples are shown in table 1.

In the examples and comparative examples in table 1, the numerical values described in the items of the (meth) acrylic copolymer (a), the ultraviolet absorber (B), the photoinitiator (C), the crosslinking agent, the light-resistant stabilizer, and the metal corrosion inhibitor are parts by mass.

[ Table 1]

The transparent double-sided adhesive sheets of examples 1 to 7 were able to suppress deterioration of the adhesive sheet itself under exposure conditions without hindering photocuring by using an ultraviolet absorber and a photoinitiator having specific absorption coefficients and controlling the amounts of addition thereof, and therefore were able to suppress deterioration of the adhesive sheet itself particularly under UV irradiation conditions and were excellent in ultraviolet ray foaming resistance.

In particular, in the transparent double-sided adhesive sheets of examples 1 to 5 and 7, since the absorption coefficient at 405nm of the photoinitiator was small, photocuring of the adhesive was not easily performed even when stored in a fluorescent lamp under high illumination, and the storage stability was excellent.

Further, in examples 1 and 4, a metal corrosion inhibitor was added, and the silver metal corrosion resistance was excellent. Among them, example 4, in which no carboxylic acid was contained in the (meth) acrylate (co) polymer (a), was extremely excellent in silver corrosion resistance, and was particularly suitable for use in the case of being attached to a conductive member formed of a metal material containing silver.

On the other hand, the transparent double-sided adhesive sheet 7 of comparative example 1 used an ultraviolet absorber having a high absorption coefficient at a wavelength of 380nm, which inhibited activation of the photoinitiator, and the transparent adhesive sheet did not sufficiently undergo photocuring even when irradiated with light, and had poor heat-resistant reliability and UV-resistant reliability. In comparative example 2 in which the photoinitiator was added with a larger amount of the ultraviolet absorber, the ultraviolet absorber itself plasticized the adhesive sheet, or inhibited activation of the photoinitiator to some extent, and the cohesive force after photocuring was lowered, and therefore, the heat resistance reliability and UV resistance reliability were poor.

In the case of the transparent double-sided pressure-sensitive adhesive sheet containing no ultraviolet absorber as in comparative example 3, deterioration of the pressure-sensitive adhesive sheet itself was not suppressed during exposure to ultraviolet light, and a large amount of decomposed products (outgas) were generated from the pressure-sensitive adhesive sheet, and therefore, foaming and peeling were generated in the ultraviolet ray foaming resistance test.

Industrial applicability

The pressure-sensitive adhesive sheet of the present invention is excellent in thermal expansion resistance, ultraviolet expansion resistance, storage stability and corrosion resistance, and therefore can be used for optical applications, particularly for image display devices.

Claims (19)

1. An adhesive sheet having an adhesive layer formed from an adhesive composition containing: (meth) acrylate (co) polymers free of carboxyl group-containing monomers as structural units, UV absorbers, photoinitiators and metal corrosion inhibitors,

the ultraviolet absorbent has an absorption coefficient of 1 × 10 at a wavelength of 340nm ³ mL/(g cm) or more and an absorption coefficient at a wavelength of 380nm of less than 1X 10 ³ mL/(g·cm)，

The adhesive composition contains the ultraviolet absorber in a ratio of 0.1 to 1.6% by mass relative to the total mass of the adhesive composition,

the water solubility of the metal corrosion inhibitor at 25 ℃ is more than 50g/L,

the adhesive layer formed from the adhesive composition has a property of being photo-cured by light irradiation,

the gel fraction of the pressure-sensitive adhesive sheet before main curing is 5% or less.

2. The adhesive sheet according to claim 1, wherein the adhesive composition contains the ultraviolet absorber in a ratio of 0.1 to 1.4% by mass relative to the total mass of the adhesive composition.

3. The 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 relative to 100 parts by mass of the photoinitiator.

4. The adhesive sheet according to claim 1 or 2, wherein the photoinitiator has an absorption coefficient at a wavelength of 405nm of less than 10 mL/(g-cm).

5. The adhesive sheet according to claim 1 or 2, wherein the photoinitiator is a hydrogen abstraction type photoinitiator.

6. The adhesive sheet according to claim 1 or 2, wherein the gel fraction of the adhesive sheet after main curing is 30% or more.

7. The adhesive sheet according to claim 1, wherein the (meth) acrylate (co) polymer is formed with a chemical bond based on a combination of any functional group of a hydroxyl group and an isocyanate group, or an amino group and an isocyanate group.

8. The adhesive sheet according to claim 1, wherein the (meth) acrylate (co) polymer further has a radical polymerizable functional group.

9. The adhesive sheet according to claim 1, wherein the (meth) acrylate (co) polymer is a graft copolymer having a macromonomer as a branching component.

10. The adhesive sheet according to claim 1, wherein the metal corrosion inhibitor has an absorption coefficient of 365nm of 20 mL/(g-cm) or less.

11. The adhesive sheet according to claim 1, wherein the adhesive composition further comprises a light stabilizer.

12. The adhesive sheet according to claim 1, wherein the metal corrosion inhibitor is a triazole-based compound.

13. The adhesive sheet according to claim 1, 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.

14. The adhesive sheet according to claim 1, wherein the adhesive composition contains a metal corrosion inhibitor in a ratio of 10 to 200 parts by mass relative to 100 parts by mass of the photoinitiator.

15. The adhesive sheet according to claim 1, wherein the adhesive composition comprises a cleavage type photoinitiator as the photoinitiator.

16. A release film-equipped adhesive sheet comprising: the adhesive sheet according to any one of claims 1 to 15; and a release film which is laminated on at least the front and back surfaces of the pressure-sensitive adhesive sheet and has a light transmittance of 40% or less for light having a wavelength of 410nm or less.

17. A laminate for image display device construction, which is formed using the adhesive sheet according to any one of claims 1 to 15 and 1 or more image display device constituent members.

18. The laminate for image display device formation according to claim 17, wherein the image display device-forming member is a conductive member having a transparent conductive layer.

19. An image display device formed using the laminate for image display device construction according to claim 18.

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