JP7513690B2 - Pressure-sensitive adhesive composition for organic EL display devices, pressure-sensitive adhesive layer for organic EL display devices, polarizing film with pressure-sensitive adhesive layer for organic EL display devices, and organic EL display device - Google Patents

Description

The present invention relates to a pressure-sensitive adhesive composition for organic electroluminescence (EL) display devices (OLED). The present invention also relates to a pressure-sensitive adhesive layer for organic EL display devices formed from the pressure-sensitive adhesive composition for organic EL display devices, and a polarized film with a pressure-sensitive adhesive layer having the pressure-sensitive adhesive layer. Furthermore, the present invention relates to an organic EL display device using the pressure-sensitive adhesive layer and/or the polarized film.

In recent years, organic EL display devices equipped with organic EL panels have come to be widely used in various applications such as mobile phones, car navigation devices, PC monitors, and televisions. In organic EL display devices, a circular polarizer (such as a laminate of a polarizer and a quarter-wave plate) is usually placed on the viewing surface of the organic EL panel to prevent external light from being reflected by the metal electrode (cathode) and being viewed as a mirror surface. In addition, a decorative panel or the like may be further laminated on the circular polarizer laminated on the viewing surface of the organic EL panel. The components of the organic EL display device, such as the circular polarizer and the decorative panel, are usually laminated via a bonding material such as an adhesive layer or an adhesive layer.

In image display devices such as organic EL display devices, components within the image display device may deteriorate due to incident ultraviolet light, and it is known to provide a layer containing an ultraviolet absorber in order to suppress deterioration due to the ultraviolet light. Specifically, for example, a transparent double-sided adhesive sheet for image display devices that has at least one ultraviolet absorbing layer, has a light transmittance of 30% or less at a wavelength of 380 nm, and has a visible light transmittance of 80% or more at wavelengths longer than 430 nm (see, for example, Patent Document 1), and an adhesive sheet having an adhesive layer containing an acrylic polymer and a triazine ultraviolet absorber are known (see, for example, Patent Document 2).

In addition, organic EL display devices are used in combination with touch panels having electrostatic capacitance touch sensors. As electrostatic capacitance touch sensors become more widespread, higher performance is required. Therefore, high performance is also required for the adhesive layer applied to the electrostatic capacitance touch sensor. However, due to the thinning of modules in organic EL display devices, the large screen size, and the high definition of organic EL elements, there is a concern that the driving noise during display driving of the organic EL panel may adversely affect the sensing of the electrostatic capacitance touch sensor, causing malfunction. The malfunction due to the driving noise may occur if the dielectric constant of the adhesive layer is high. Therefore, as an adhesive for forming an adhesive layer with a low dielectric constant, for example, an adhesive based on a (meth)acrylic polymer mainly composed of an alkyl (meth)acrylate having a long-chain alkyl group has been proposed (for example, Patent Document 3). The adhesive layer with a low dielectric constant can reduce the influence of driving noise from the organic EL panel on the electrostatic capacitance touch sensor.

JP 2012-211305 A JP 2013-75978 A JP 2013-082880 A

The adhesive sheets described in Patent Documents 1 and 2 are capable of controlling the transmittance of light with a wavelength of 380 nm, but when used in an organic EL display device, the adhesive sheets are not sufficient because the organic EL elements may deteriorate over long periods of use. This is because the adhesive sheets described in Patent Documents 1 and 2 are capable of absorbing light with a wavelength of 380 nm, but do not sufficiently absorb light in the wavelength range (380 nm to 430 nm) that is shorter than the light-emitting region of the organic EL element (longer than 430 nm), and it is believed that deterioration occurs due to the transmitted light.

Therefore, in order to prevent deterioration of the organic EL element, it is necessary to use a layer in the organic EL display device that suppresses the transmission of light with wavelengths (380 nm to 430 nm) shorter than the light-emitting region of the organic EL element (longer than 430 nm), can ensure sufficient transmittance of visible light in the light-emitting region of the organic EL element, and has high transparency.

On the other hand, organic EL display devices are used for various purposes. For example, when used in modular devices for mobile applications, drop impact resistance is required. Therefore, the adhesive layer used in the organic EL display device is required to have resistance to peeling during a drop impact as drop impact resistance. In particular, the adhesive layer with a low dielectric constant described in Patent Document 3 has a high glass transition point (Tg), and therefore does not have sufficient drop impact resistance (resistance to peeling during a drop impact).

The present invention aims to provide an adhesive layer for an organic EL display device that can suppress deterioration of the organic EL element, has high transparency, and further has low dielectric properties that can reduce the effects of driving noise in the organic EL panel, and has excellent resistance to peeling when dropped.

The present invention also aims to provide a polarizing film with an adhesive layer, which has a polarizing film and the adhesive layer for an organic EL display device, and further aims to provide an organic EL display device that includes the adhesive layer and/or the polarizing film with an adhesive layer.

As a result of intensive research into solving the above problems, the inventors discovered the following adhesive layer for an organic EL display device, and completed the present invention.

That is, the present invention provides a pressure-sensitive adhesive layer for an organic EL display device, which is formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer and an ultraviolet absorber,
The (meth)acrylic polymer is obtained by polymerizing a monomer component including a monofunctional monomer component including an alkyl(meth)acrylate (A) having an alkyl group having 8 or less carbon atoms at an ester terminal and an alkyl(meth)acrylate (B) having an alkyl group having 12 to 24 carbon atoms at an ester terminal,
a ratio (a: weight %) of the alkyl (meth)acrylate (A) and a ratio (b: weight %) of the alkyl (meth)acrylate (B) in 100 weight % of the monofunctional monomer component satisfy the following formulas (1) and (2):
Formula (1): 60≦{(a)+(b)}
Formula (2): 1.4≦{(a)/(b)}≦2
And the pressure-sensitive adhesive layer is
The peak value of tan δ (Tg) when dynamic viscoelasticity is measured at a frequency of 1 Hz is −20 to −5° C.;
The transmittance at a wavelength of 380 nm is 10% or less, and the transmittance at a wavelength of 450 nm is 85% or more,
The present invention relates to a pressure-sensitive adhesive layer for an organic EL display device, characterized in that the total light transmittance is 85% or more and the haze is 1% or less.

In the adhesive layer for an organic EL display device, it is preferable that the maximum absorption wavelength of the absorption spectrum of the ultraviolet absorber is in the wavelength region of 300 to 400 nm.

In the adhesive layer for an organic EL display device, the monofunctional monomer component may further contain at least one aggregating monomer selected from a cyclic nitrogen-containing monomer and an alicyclic structure-containing monomer. The proportion of the aggregating monomer in the monofunctional monomer component is preferably 10 to 22% by weight.

In the adhesive layer for an organic EL display device, the monofunctional monomer component may further contain a hydroxyl group-containing monomer. The proportion of the hydroxyl group-containing monomer in the monofunctional monomer component is preferably 1.5 to 10% by weight.

In the adhesive layer for an organic EL display device, the monomer component may further contain 3 parts by weight or less of a polyfunctional monomer per 100 parts by weight of the monofunctional monomer component.

In the adhesive layer for an organic EL display device, the adhesive composition may further contain a dye compound whose absorption spectrum has a maximum absorption wavelength in the wavelength region of 380 to 430 nm.

In the adhesive layer for an organic EL display device, the adhesive composition may further contain 3 parts by weight or less of a crosslinking agent per 100 parts by weight of the monofunctional monomer component.

In the adhesive layer for an organic EL display device, the adhesive composition may further contain 3 parts by weight or less of a silane coupling agent per 100 parts by weight of the monofunctional monomer component.

In the adhesive layer for an organic EL display device, the adhesive composition may further contain a photopolymerization initiator.

The adhesive layer for an organic EL display device preferably has a relative dielectric constant of 3.5 or less at a frequency of 100 kHz.

The adhesive layer for an organic EL display device preferably has a gel fraction of 50 to 95% by weight.

The pressure-sensitive adhesive layer for an organic EL display device preferably has a 180-degree peel adhesive strength (peel speed 300 mm/min) to non-alkali glass of 7 N/20 mm or more.

It is preferable that the adhesive layer for an organic EL display device has a separator on at least one side.

The present invention also relates to a polarizing film with an adhesive layer for an organic EL display device, which comprises a polarizing film and the adhesive layer for an organic EL display device.

The polarizing film with an adhesive layer for an organic EL display device is a polarizing film having a transparent protective film on one side of a polarizer and a retardation film on the other side, and it is preferable that the adhesive layer for an organic EL display device is provided on the side of the retardation film opposite to the side that contacts the polarizer and/or the side of the transparent protective film opposite to the side that contacts the polarizer.

The pressure-sensitive adhesive layer-attached polarizing film for an organic EL display device is a pressure-sensitive adhesive layer-attached polarizing film having a first pressure-sensitive adhesive layer, a transparent protective film, a polarizer, a second pressure-sensitive adhesive layer, a retardation film, and a third pressure-sensitive adhesive layer in this order,
At least one of the first pressure-sensitive adhesive layer, the second pressure-sensitive adhesive layer, and the third pressure-sensitive adhesive layer is preferably the pressure-sensitive adhesive layer for an organic EL display device.

In the polarizing film with an adhesive layer for an organic EL display device, it is preferable that the retardation film is a quarter-wave plate and the polarizing film is a circular polarizing film.

The present invention also relates to an organic EL display device that uses at least one of the above-mentioned adhesive layer for an organic EL display device or the above-mentioned polarizing film with an adhesive layer for an organic EL display device.

The organic EL display device is a touch panel-equipped organic EL display device including an organic EL panel, a circularly polarizing film provided in this order from a viewing side of the organic EL panel, and a touch panel having at least one sensor film,
In a preferred embodiment, the pressure-sensitive adhesive layer for an organic EL display device is provided on the viewing side of the circularly polarizing film so as to be in contact with at least one sensor film.

As described above, the adhesive layer for the organic EL display device is suitable as an adhesive layer for a touch panel that is used to be in contact with at least one sensor film in the organic EL display device with a touch panel.

The adhesive composition forming the adhesive layer for an organic EL display device of the present invention is formed from an adhesive composition containing an ultraviolet absorber in addition to an acrylic polymer as a base polymer. The ultraviolet absorber prevents light in the near ultraviolet to ultraviolet region from passing through, thereby suppressing deterioration caused by ultraviolet light. The adhesive layer for an organic EL display device of the present invention also has high transparency, and can suppress deterioration of the organic EL element without interfering with the display performance of the organic EL element. Therefore, an organic EL display device using the adhesive layer for an organic EL display device of the present invention and/or a polarizing film with an adhesive layer including the adhesive layer for an organic EL display device has excellent weather deterioration resistance and can have a long life.

In addition, according to the Clausius-Mossotti formula, it is believed that the dielectric constant can be reduced by reducing the dipole moment of the molecule and increasing the molar volume. The acrylic polymer according to the present invention has an alkyl (meth)acrylate (B) having a long-chain alkyl group as a monomer unit, and can reduce the dielectric constant of the adhesive layer. Such an adhesive layer with a low dielectric constant can reduce the influence of malfunction due to the influence of driving noise from an organic EL panel on a capacitive touch sensor. Therefore, the adhesive layer of the present invention can be suitably applied to a touch sensor with a high response speed and high sensitivity.

The acrylic polymer according to the present invention contains monomer units of two types of (meth)acrylates (A) and (B) having different carbon numbers in the alkyl group at a predetermined ratio, and the adhesive layer of the present invention has a glass transition temperature (Tg) controlled to -5°C or less, despite having an alkyl (meth)acrylate (B) having a long-chain alkyl group as a monomer unit. Thus, according to the present invention, an adhesive layer having drop impact resistance (peel resistance upon drop impact) while maintaining the adhesive properties as an adhesive layer and having a low dielectric constant as described above can be obtained. The adhesive layer of the present invention can provide a mobile module device having excellent peel resistance upon drop impact by filling the gap between a printed glass (such as a cover glass), an optical film, or a capacitive touch sensor in an organic EL display device and an air layer above the organic EL display device.

1A to 1C are cross-sectional views each showing a schematic diagram of one embodiment of a pressure-sensitive adhesive layer-attached polarizing film for an organic EL display device according to the present invention. 1 is a cross-sectional view illustrating an embodiment of an organic EL display device of the present invention. 1 is a cross-sectional view illustrating an embodiment of an organic EL display device of the present invention. 1 is a cross-sectional view illustrating an embodiment of an organic EL display device of the present invention.

1. Pressure-sensitive adhesive composition for organic EL display device The pressure-sensitive adhesive layer for an organic EL display device of the present invention is formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer and an ultraviolet absorbing agent.

(1) Partial Polymer of Monomer Component and (Meth)acrylic Polymer The (meth)acrylic polymer contained in the pressure-sensitive adhesive composition is obtained by polymerizing a partial polymer of a monomer component containing a monofunctional monomer component including an alkyl(meth)acrylate (A) having an alkyl group with 8 or less carbon atoms at the ester terminal and an alkyl(meth)acrylate (B) having an alkyl group with 12 to 24 carbon atoms at the ester terminal, and/or the monomer component. Note that "alkyl(meth)acrylate" refers to alkyl acrylate and/or alkyl methacrylate, and (meth) in the present invention has the same meaning.

The alkyl (meth)acrylate (A) and the alkyl (meth)acrylate (B) are used such that a ratio (a: weight %) of the alkyl (meth)acrylate (A) and a ratio (b: weight %) of the alkyl (meth)acrylate (B) in 100 weight % of the monofunctional monomer component in the monomer component satisfy the following formulas (1) and (2).
Formula (1): 60≦{(a)+(b)}
Formula (2): 1.4≦{(a)/(b)}≦2
By using the alkyl (meth)acrylate (A) and the alkyl (meth)acrylate (B) within the above ranges, these monomer units can be introduced into the (meth)acrylic polymer in a well-balanced manner, and the pressure-sensitive adhesive layer can be endowed with low dielectric properties and resistance to peeling during a drop impact.

The sum of the proportion (a) of the alkyl (meth)acrylate (A) and the proportion (b) of the alkyl (meth)acrylate (B) in the formula (1) {(a) + (b)} is 60% by weight or more relative to 100% by weight of the monofunctional monomer component in the monomer component. From the viewpoints of the ease of balancing the adhesive properties and the drop impact resistance, the sum is preferably 65% by weight or more, and more preferably 70% by weight or more. On the other hand, the sum may be 100% by weight, but from the viewpoints of ensuring cohesive strength and crosslinking points, ensuring elastic modulus at high temperatures, and wettability to the adherend, it is preferably 95% by weight or less, and more preferably 90% by weight or less.

In addition, the ratio (a)/(b) of the proportion (a) of the alkyl (meth)acrylate (A) to the proportion (b) of the alkyl (meth)acrylate (B) in formula (2) is in the range of 1.4 to 2, and from the viewpoint of achieving both a reduction in the dielectric constant and drop impact resistance, it is preferably 1.5 to 2, and more preferably 1.6 to 2.

The proportion (a) of the alkyl (meth)acrylate (A) is preferably 30 to 60% by weight, more preferably 30 to 56% by weight. The proportion (b) of the alkyl (meth)acrylate (B) is preferably 20 to 38% by weight, more preferably 22 to 36% by weight.

<Alkyl (meth)acrylate (A)>
The alkyl group having 8 or less carbon atoms in the alkyl (meth)acrylate (A) may be either linear or branched, but from the viewpoint of imparting adhesiveness to the adhesive layer and resistance to drop impact, the alkyl group preferably has 2 to 8 carbon atoms, more preferably 4 to 8 carbon atoms. The alkyl (meth)acrylate (A) is preferably an alkyl acrylate from the viewpoint of a relatively low glass transition point (Tg) and a relatively fast radical polymerization reactivity. The alkyl (meth)acrylate (A) preferably has a homopolymer Tg of -90 to -20°C, more preferably -85 to -30°C, and even more preferably -80 to -40°C, from the viewpoint of imparting adhesiveness to the adhesive layer. The Tg of the homopolymer is a value measured by simultaneous differential thermal analysis (TG-DTA) (the same applies below to the measurement of the Tg of the homopolymer).

Examples of the alkyl (meth)acrylate (A) include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, isoamyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, and n-nonyl (meth)acrylate. These can be used alone or in combination.

<Alkyl (meth)acrylate (B)>
The alkyl group having 12 to 24 carbon atoms in the alkyl (meth)acrylate (B) may be either linear or branched, but is preferably branched from the viewpoint of satisfying a low dielectric constant and an appropriate modulus of elasticity, and more preferably is a branched alkyl group having 14 to 22 carbon atoms. In the case of a linear alkyl group, it is preferable that the number of carbon atoms is 18 or more from the viewpoint of satisfying a low dielectric constant and an appropriate modulus of elasticity. It is considered that the long-chain alkyl group of the alkyl (meth)acrylate has a branched alkyl group, which increases the molar volume and reduces the dipole moment, thereby obtaining a pressure-sensitive adhesive layer having a balance between the two. The alkyl (meth)acrylate (B) is preferably an alkyl acrylate from the viewpoint of a relatively low glass transition point (Tg) and a relatively fast radical polymerization reactivity. From the viewpoint of imparting a low dielectric constant and an appropriate elastic modulus to the pressure-sensitive adhesive layer, the alkyl (meth)acrylate (B) preferably has a homopolymer Tg of −80 to 0° C., more preferably −75 to −5° C., and even more preferably −70 to −10° C.

Examples of the alkyl (meth)acrylate (B) include lauryl (meth)acrylate, isododecyl (meth)acrylate, tridecyl (meth)acrylate, isotridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, isopentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, isohexadecyl (meth)acrylate, isoheptadecyl (meth)acrylate, stearyl (meth)acrylate, and isostearyl (meth)acrylate.

<Copolymerization Monomer>
The monofunctional monomer in the monomer component may contain a copolymerizable monomer other than the alkyl (meth)acrylates (A) and (B). The copolymerizable monomer may be used as the remainder of the alkyl (meth)acrylates (A) and (B) in the monofunctional monomer.

The copolymerizable monomer may include, for example, at least one aggregating monomer selected from a cyclic nitrogen-containing monomer and an alicyclic structure-containing monomer. The aggregating monomer is preferable because its homopolymer has a high Tg, and can lower the dielectric constant, ensure cohesive force, and maintain a high elastic modulus at high temperatures (80°C). The Tg of the homopolymer of the aggregating monomer is preferably 0 to 200°C, more preferably 5 to 180°C, and even more preferably 10 to 160°C.

As the cyclic nitrogen-containing monomer, those having a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group and having a cyclic nitrogen structure can be used without any particular limitation. The cyclic nitrogen structure is preferably one having a nitrogen atom in the cyclic structure. Examples of the cyclic nitrogen-containing monomer include lactam-based vinyl monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; vinyl-based monomers having nitrogen-containing heterocycles such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine. In addition, (meth)acrylic monomers containing heterocycles such as morpholine ring, piperidine ring, pyrrolidine ring, and piperazine ring can be mentioned. Specifically, N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine can be mentioned. Among the cyclic nitrogen-containing monomers, lactam vinyl monomers are preferred.

As the alicyclic structure-containing monomer, those having a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group and having an alicyclic structure can be used without particular limitation. The alicyclic structure is a cyclic hydrocarbon structure, and from the viewpoint of reducing the dielectric constant, it preferably has 5 or more carbon atoms, preferably has 6 to 24 carbon atoms, more preferably has 8 to 20 carbon atoms, and even more preferably has 10 to 18 carbon atoms. Examples of the alicyclic structure-containing monomer include (meth)acrylic monomers such as cyclopropyl (meth)acrylate, cyclobutyl (meth)acrylate, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, cyclooctyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, HPMPA (chemical formula 1 below), TMA-2 (chemical formula 2 below), and HCPA (chemical formula 3 below). Of these, cyclohexyl (meth)acrylate, HPMPA, TMA-2 and HCPA are preferred, and cyclohexyl (meth)acrylate, HPMPA and TMA-2 are particularly preferred.

The proportion of the aggregating monomer is preferably 10 to 22% by weight, more preferably 12 to 20% by weight, based on the total amount of monofunctional monomer components.

In addition, the copolymerization monomer in the monofunctional monomer may contain a hydroxyl group-containing monomer. As the hydroxyl group-containing monomer, a monomer having a polymerizable functional group with an unsaturated double bond such as a (meth)acryloyl group or a vinyl group and having a hydroxyl group may be used without any particular limitation. Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate; and hydroxyalkyl cycloalkane (meth)acrylates such as (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Other examples include hydroxyethyl (meth)acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, etc. These can be used alone or in combination. Among these, hydroxyalkyl (meth)acrylates are preferred.

The proportion of the hydroxyl group-containing monomer is preferably in the range of 0.1 to 20% by weight based on the total amount of monofunctional monomers in order to enhance adhesive strength and cohesive strength. In particular, from the viewpoint of controlling the Tg of the adhesive layer within the range of the present invention to achieve good drop impact resistance (peel resistance upon drop impact), the proportion is preferably 1.5 to 10% by weight. The proportion of the hydroxyl group-containing monomer is more preferably 2% by weight or more, and even more preferably 3% by weight or more. The more hydroxyl groups there are, the more the adhesive strength (to glass) improves, the higher the elastic modulus can be maintained at high temperatures (80°C), and the more advantageous it is in preventing peeling during reliability tests. On the other hand, if the amount of the hydroxyl group-containing monomer is too large, the dielectric constant tends to increase, the adhesive layer may harden, and the adhesive strength may decrease. In addition, the adhesive may become too viscous or gel. Therefore, the amount of the hydroxyl group-containing monomer is preferably 9% by weight or less, more preferably 8% by weight or less, and even more preferably 7% by weight or less, based on the total amount of the monofunctional monomer components that form the (meth)acrylic polymer.

The copolymerizable monomer in the monofunctional monomer may contain a functional group-containing monomer other than those mentioned above, such as a carboxyl group-containing monomer or a monomer having a cyclic ether group.

As the carboxyl group-containing monomer, any monomer having a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and having a carboxyl group can be used without any particular restrictions. Examples of the carboxyl group-containing monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc., which can be used alone or in combination. Anhydrides of itaconic acid and maleic acid can be used. Among these, acrylic acid and methacrylic acid are preferred, and acrylic acid is particularly preferred. In addition, a carboxyl group-containing monomer can be used as the monomer component used in the production of the (meth)acrylic polymer of the present invention, and on the other hand, a carboxyl group-containing monomer may not be used.

As the monomer having a cyclic ether group, those having a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group, and having a cyclic ether group such as an epoxy group or an oxetane group, can be used without any particular restrictions. Examples of the epoxy group-containing monomer include glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, etc. Examples of the oxetane group-containing monomer include 3-oxetanylmethyl (meth)acrylate, 3-methyl-oxetanylmethyl (meth)acrylate, 3-ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate, 3-hexyl-oxetanylmethyl (meth)acrylate, etc. These can be used alone or in combination.

The ratio of the carboxyl group-containing monomer and the monomer having a cyclic ether group to the total amount of the monofunctional monomer is preferably 8% by weight or less, more preferably 5% by weight or less. When the pressure-sensitive adhesive layer of the present invention is also used in an embodiment in which it is brought into contact with a sensor film, it is preferable to adopt an embodiment in which the carboxyl group-containing monomer is not used.

In addition, examples of copolymerizable monomers in the monofunctional monomer include alkyl (meth)acrylates represented by CH ₂ ═C(R ¹ )COOR ² (wherein R ¹ represents hydrogen or a methyl group, and R ² represents an alkyl group having 9 to 11 carbon atoms, a substituted alkyl group having 1 to 3 carbon atoms, or a cyclic cycloalkyl group).

Here, the substituent of the substituted alkyl group having 1 to 3 carbon atoms as ^R2 is preferably an aryl group having 3 to 8 carbon atoms or an aryloxy group having 3 to 8 carbon atoms. The aryl group is not limited, but a phenyl group is preferable.

Examples of such monomers represented by CH ₂ ═C(R ¹ )COOR ² include phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, isobornyl (meth)acrylate, etc. These can be used alone or in combination.

The proportion of the (meth)acrylate represented by the formula CH ₂ ═C(R ¹ )COOR ² is preferably 10% by weight or less based on the total amount of the monofunctional monomers.

Other copolymerizable monomers that can be used include vinyl acetate, vinyl propionate, styrene, α-methylstyrene; glycol-based acrylic ester monomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; acrylic ester monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, and 2-methoxyethyl acrylate; amide group-containing monomers, amino group-containing monomers, imide group-containing monomers, and vinyl ether monomers.

Further examples include silane-based monomers containing silicon atoms. Examples of silane-based monomers include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, 10-acryloyloxydecyltriethoxysilane, and 10-acryloyloxydecyltriethoxysilane.

In addition to the monofunctional monomers exemplified above, the monomer components forming the (meth)acrylic polymer of the present invention may contain polyfunctional monomers as necessary to adjust the cohesive strength of the adhesive.

A polyfunctional monomer is a monomer having at least two polymerizable functional groups having an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and examples thereof include (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and 1,2-ethylene glycol di(meth)acrylate. , 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, and other polyhydric alcohol and (meth)acrylic acid ester compounds; allyl (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butylene di(meth)acrylate, hexylene di(meth)acrylate, and the like. Among these, trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, and dipentaerythritol hexa(meth)acrylate can be preferably used. The polyfunctional monomer can be used alone or in combination of two or more.

The amount of polyfunctional monomer used varies depending on its molecular weight, number of functional groups, etc., but is preferably 3 parts by weight or less, more preferably 2 parts by weight or less, and even more preferably 1 part by weight or less, per 100 parts by weight of monofunctional monomers in total. The lower limit is not particularly limited, but is preferably 0 parts by weight or more, and more preferably 0.001 parts by weight or more. By using the polyfunctional monomer in an amount within the above range, the adhesive strength can be improved.

The (meth)acrylic polymer can be produced by any known production method, such as solution polymerization, radiation polymerization such as ultraviolet (UV) polymerization, bulk polymerization, emulsion polymerization, and other radical polymerization methods. The resulting (meth)acrylic polymer may be any of a random copolymer, a block copolymer, a graft copolymer, and the like.

In addition, in the present invention, partial polymers of the above monomer components can also be suitably used.

When the (meth)acrylic polymer is produced by radical polymerization, a polymerization initiator, a chain transfer agent, an emulsifier, etc. used in radical polymerization can be appropriately added to the monomer components to carry out polymerization. The polymerization initiator, the chain transfer agent, the emulsifier, etc. used in the radical polymerization are not particularly limited and can be appropriately selected and used. The weight average molecular weight of the (meth)acrylic polymer can be controlled by the amount of polymerization initiator and the chain transfer agent used and the reaction conditions, and the amount used is appropriately adjusted depending on the type of these.

For example, in solution polymerization, ethyl acetate, toluene, etc., are used as the polymerization solvent. In a specific example of solution polymerization, the reaction is carried out under a stream of inert gas such as nitrogen, with the addition of a polymerization initiator, usually at about 50 to 70°C, for about 5 to 30 hours.

Examples of thermal polymerization initiators used in solution polymerization include 2,2'-azobisisobutyronitrile, 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2-methylpropionic acid) dimethyl, 4,4'-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis[2-(5-methyl-2-imidazoline-2-isopropyl]acetate, azo initiators such as 2,2'-azobis(N,N'-dimethyleneisobutylamidine)dihydrochloride, 2,2'-azobis(2-methylpropionamidine)disulfate, 2,2'-azobis(N,N'-dimethyleneisobutylamidine), and 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]hydrate (VA-057, manufactured by Wako Pure Chemical Industries, Ltd.); persulfates such as potassium persulfate and ammonium persulfate, and di(2-ethylhexyl)peroxydiamine; Examples of initiators include, but are not limited to, peroxide initiators such as carbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxyneodecanoate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, di(4-methylbenzoyl)peroxide, dibenzoyl peroxide, t-butylperoxyisobutyrate, 1,1-di(t-hexylperoxy)cyclohexane, t-butyl hydroperoxide, and hydrogen peroxide; and redox initiators that combine a peroxide and a reducing agent, such as a combination of a persulfate and sodium hydrogen sulfite, or a combination of a peroxide and sodium ascorbate.

The polymerization initiator may be used alone or in a mixture of two or more kinds, but is preferably used in an amount of about 1 part by weight or less, more preferably about 0.005 to 1 part by weight, and even more preferably about 0.02 to 0.5 parts by weight, per 100 parts by weight of the total amount of the monomer components.

When 2,2'-azobisisobutyronitrile is used as the polymerization initiator, the amount of the polymerization initiator used is preferably about 0.2 parts by weight or less, and more preferably about 0.06 to 0.2 parts by weight, per 100 parts by weight of the total amount of the monomer components.

Examples of chain transfer agents include lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, and 2,3-dimercapto-1-propanol. The chain transfer agents may be used alone or in combination of two or more, but the total content is about 0.3 parts by weight or less per 100 parts by weight of the total amount of the monomer components.

Examples of emulsifiers used in emulsion polymerization include anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, polyoxyethylene alkyl ether ammonium sulfate, and sodium polyoxyethylene alkyl phenyl ether sulfate, and nonionic emulsifiers such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, and polyoxyethylene-polyoxypropylene block polymer. These emulsifiers may be used alone or in combination of two or more.

Furthermore, examples of reactive emulsifiers that have radically polymerizable functional groups such as propenyl groups and allyl ether groups introduced therein include Aqualon HS-10, HS-20, KH-10, BC-05, BC-10, and BC-20 (all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and Adeka Reasoap SE10N (manufactured by ADEKA Corporation). The amount of emulsifier used is preferably 5 parts by weight or less per 100 parts by weight of the total amount of monomer components.

When the (meth)acrylic polymer is produced by radiation polymerization, the monomer component can be polymerized by irradiating it with radiation such as electron beams or ultraviolet (UV) rays. Among these, ultraviolet polymerization is preferred. Below, ultraviolet polymerization, which is a preferred form of radiation polymerization, will be described.

When carrying out ultraviolet polymerization, it is preferable to include a photopolymerization initiator in the monomer component, because of the advantage of being able to shorten the polymerization time. Therefore, when carrying out ultraviolet polymerization, it is preferable to form, for example, by ultraviolet polymerization of a monomer component containing a monofunctional monomer component containing the alkyl (meth)acrylates (A) and (B) and/or a partial polymer of the monomer component, an ultraviolet absorber, and an ultraviolet curing acrylic adhesive composition containing a photopolymerization initiator. The adhesive layer formed by ultraviolet polymerization of the ultraviolet curing acrylic adhesive composition can be formed to a thickness of 150 μm or more, and is preferable because an adhesive layer of a wide range of thicknesses can be formed.

The photopolymerization initiator is not particularly limited, but preferably contains a photopolymerization initiator (A) having an absorption band at wavelengths of 400 nm or more. When the adhesive composition contains an ultraviolet absorber, ultraviolet light is absorbed by the ultraviolet absorber when ultraviolet polymerization is performed, and sufficient polymerization cannot be achieved. However, photopolymerization initiator (A) having an absorption band at wavelengths of 400 nm or more is preferable because sufficient polymerization can be achieved despite the inclusion of an ultraviolet absorber.

Examples of photopolymerization initiators (A) that have an absorption band at wavelengths of 400 nm or more include bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (Irgacure 819, manufactured by BASF) and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (LUCIRIN TPO, manufactured by BASF).

The photopolymerization initiator (A) having an absorption band at wavelengths of 400 nm or more may be used alone or in combination of two or more.

The amount of photopolymerization initiator (A) having an absorption band at wavelengths of 400 nm or more added is not particularly limited, but is preferably less than the amount of ultraviolet absorber added, described below, and is preferably 2 parts by weight or less, more preferably about 0.005 to 1 part by weight, and even more preferably about 0.02 to 0.8 parts by weight, per 100 parts by weight of the monofunctional monomer component that forms the (meth)acrylic polymer. It is preferable that the amount of photopolymerization initiator (A) added is within the above range, since ultraviolet polymerization can proceed sufficiently.

The photopolymerization initiator may contain a photopolymerization initiator (B) having an absorption band at a wavelength of less than 400 nm. The photopolymerization initiator (B) is not particularly limited as long as it generates radicals by ultraviolet light and initiates photopolymerization and has an absorption band at a wavelength of less than 400 nm, and any commonly used photopolymerization initiator may be suitably used. For example, benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, etc. may be used.

Specific examples of benzoin ether-based photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethan-1-one, and anisoin methyl ether.

Examples of acetophenone-based photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, and 4-t-butyldichloroacetophenone.

Examples of α-ketol photopolymerization initiators include 2-methyl-2-hydroxypropiophenone, 1-[4-(2-hydroxyethyl)phenyl]-2-hydroxy-2-methylpropan-1-one, etc.

Examples of photoactive oxime-based photopolymerization initiators include 1-phenyl-1,2-propanedione-2-(O-ethoxycarbonyl)-oxime.

Benzoin-based photopolymerization initiators include, for example, benzoin.

Benzyl-based photopolymerization initiators include, for example, benzyl.

Benzophenone-based photopolymerization initiators include, for example, benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, etc.

Ketal-based photopolymerization initiators include benzyl dimethyl ketal, etc.

Thioxanthone-based photopolymerization initiators include, for example, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, etc.

Acylphosphine oxide photopolymerization initiators include, for example, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, etc.

The photopolymerization initiator (B) having an absorption band at a wavelength of less than 400 nm may be used alone or in combination of two or more kinds. The photopolymerization initiator (B) having an absorption band at a wavelength of less than 400 nm may be added in an amount that does not impair the effects of the present invention, and the amount added is preferably about 0.005 to 0.5 parts by weight, and more preferably about 0.02 to 0.2 parts by weight, per 100 parts by weight of the monofunctional monomer component that forms the (meth)acrylic polymer.

In the present invention, when the monomer components are polymerized by ultraviolet light, it is preferable to first add a photopolymerization initiator (B) having an absorption band at a wavelength of less than 400 nm to the monomer components, and then add a photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more and an ultraviolet absorber to the partially polymerized monomer components (prepolymer composition) that have been partially polymerized by ultraviolet light irradiation, and then polymerize by ultraviolet light. When adding a photopolymerization initiator (A) having an absorption band at a wavelength of 400 nm or more to the partially polymerized monomer components (prepolymer composition) that have been partially polymerized by ultraviolet light irradiation, it is preferable to add the photopolymerization initiator after dissolving it in the monomer.

The weight-average molecular weight of the (meth)acrylic polymer of the present invention is preferably 400,000 to 3,000,000, more preferably 600,000 to 2,500,000. By making the weight-average molecular weight greater than 400,000, the durability of the adhesive layer can be satisfied, and the adhesive layer can be prevented from having a small cohesive force, which reduces the occurrence of adhesive residue. On the other hand, if the weight-average molecular weight is greater than 3,000,000, the adhesion and adhesive strength tend to decrease. Furthermore, in a solution system, the viscosity of the adhesive may become too high, making coating difficult. The weight-average molecular weight refers to a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene. It is difficult to measure the molecular weight of a (meth)acrylic polymer obtained by radiation polymerization.

<Measurement of weight average molecular weight>
The weight average molecular weight of the obtained (meth)acrylic polymer was measured by GPC (gel permeation chromatography). The sample was prepared by dissolving the sample in tetrahydrofuran to prepare a 0.1 wt % solution, leaving the solution overnight, and filtering the solution through a 0.45 μm membrane filter.
Analytical equipment: Tosoh Corporation, HLC-8120GPC
Column: Tosoh Corporation: GM7000HXL + GMHXL + GMHXL
Column size: 7.8 mm diameter x 30 cm, total 90 cm
Eluent: tetrahydrofuran (concentration 0.1% by weight)
Flow rate: 0.8 ml/min
Inlet pressure: 1.6 MPa
Detector: differential refractometer (RI)
Column temperature: 40°C
Injection volume: 100 μl
Eluent: Tetrahydrofuran Detector: Differential refractometer Standard sample: Polystyrene

(2) UV absorber The UV absorber is not particularly limited, but can be, for example, triazine UV absorber, benzotriazole UV absorber, benzophenone UV absorber, oxybenzophenone UV absorber, salicylic acid ester UV absorber, cyanoacrylate UV absorber, etc., and can be used alone or in combination of two or more. Among these, triazine UV absorber and benzotriazole UV absorber are preferred, and at least one UV absorber selected from the group consisting of triazine UV absorber having two or less hydroxyl groups in one molecule and benzotriazole UV absorber having one benzotriazole skeleton in one molecule is preferred because it has good solubility in the monomer used to form the acrylic pressure-sensitive adhesive composition and has high UV absorption ability at a wavelength of around 380 nm.

Specific examples of triazine-based UV absorbers having two or less hydroxyl groups per molecule include 2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (Tinosorb S, manufactured by BASF), 2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3,5-triazine (TINUVIN), 460, manufactured by BASF), reaction products of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-hydroxyphenyl with [(C10-C16 (mainly C12-C13) alkyloxy)methyl]oxirane (TINUVIN 400, manufactured by BASF), 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-[3-(dodecyloxy)-2-hydroxypropoxy]phenol), 2-(2,4-dihydroxyf Reaction product of 2-(4,6-diphenyl-1,3,5-triazine and (2-ethylhexyl)-glycidic acid ester (TINUVIN 405, manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[(hexyl)oxy]-phenol (TINUVIN 1577, manufactured by BASF), 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[2-(2-ethylhexanoyloxy)ethoxy]-phenol (ADK Examples include STAB LA46, manufactured by ADEKA, and 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine (TINUVIN479, manufactured by BASF).

In addition, examples of benzotriazole-based UV absorbers having one benzotriazole skeleton per molecule include 2-(2H-benzotriazole-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN 928, manufactured by BASF), 2-(2-hydroxy-5-tert-butylphenyl)-2H-benzotriazole (TINUVIN PS, manufactured by BASF), ester compound of benzenepropanoic acid and 3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy (C7-9 side chain and linear alkyl) (TINUVIN384-2, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN900, manufactured by BASF), 2-(2H-benzotriazol-2-yl )-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN 928, manufactured by BASF), reaction product of methyl-3-(3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl)propionate/polyethylene glycol 300 (TINUVIN 1130, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-p-cresol (TINUVIN P, manufactured by BASF), 2(2H-benzotriazol-2-yl)-4-6-bis(1-methyl-1-phenylethyl)phenol (TINUVIN 234, manufactured by BASF), 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-(tert-butyl)phenol (TINUVIN 326, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (TINUVIN 328, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (TINUVIN N329, manufactured by BASF), reaction product of methyl 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate and polyethylene glycol 300 (TINUVIN 213, manufactured by BASF), 2-(2H-benzotriazol-2-yl)-6-dodecyl-4-methylphenol (TINUVIN 571, manufactured by BASF), 2-[2-hydroxy-3-(3,4,5,6-tetrahydrophthalimido-methyl)-5-methylphenyl]benzotriazole (Sumisorb 250, manufactured by Sumitomo Chemical Co., Ltd.), etc.

In addition, examples of the benzophenone-based ultraviolet absorbers (benzophenone-based compounds) and oxybenzophenone-based ultraviolet absorbers (oxybenzophenone-based compounds) include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid (anhydrous and trihydrate), 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, and 2,2'-dihydroxy-4,4-dimethoxybenzophenone.

Examples of the salicylic acid ester-based ultraviolet absorber (salicylic acid ester-based compound) include phenyl-2-acryloyloxybenzoate, phenyl-2-acryloyloxy-3-methylbenzoate, phenyl-2-acryloyloxy-4-methylbenzoate, phenyl-2-acryloyloxy-5-methylbenzoate, phenyl-2-acryloyloxy-3-methoxybenzoate, phenyl-2-hydroxybenzoate, phenyl-2-hydroxy-3-methylbenzoate, phenyl-2-hydroxy-4-methylbenzoate, phenyl-2-hydroxy-5-methylbenzoate, phenyl-2-hydroxy-3-methoxybenzoate, 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate (TINUVIN120, manufactured by BASF), and the like.

Examples of the cyanoacrylate-based ultraviolet absorber (cyanoacrylate-based compound) include alkyl-2-cyanoacrylate, cycloalkyl-2-cyanoacrylate, alkoxyalkyl-2-cyanoacrylate, alkenyl-2-cyanoacrylate, and alkynyl-2-cyanoacrylate.

The maximum absorption wavelength of the absorption spectrum of the ultraviolet absorber is preferably in the wavelength region of 300 to 400 nm, and more preferably in the wavelength region of 320 to 380 nm. The method for measuring the maximum absorption wavelength is the same as the method for measuring the dye-based compound described below.

The ultraviolet absorbers may be used alone or in combination of two or more kinds, but the total content is preferably about 0.1 to 5 parts by weight, and more preferably about 0.5 to 3 parts by weight, per 100 parts by weight of the monofunctional monomer component that forms the (meth)acrylic polymer. By setting the amount of ultraviolet absorber added within the above range, the ultraviolet absorbing function of the adhesive layer can be fully exerted, and if ultraviolet polymerization is performed, it is preferable because the polymerization is not hindered.

(3) Dye Compound The pressure-sensitive adhesive composition of the present invention may further contain a dye compound having a maximum absorption wavelength in the wavelength region of 380 to 430 nm in the absorption spectrum. Here, the maximum absorption wavelength means the absorption maximum wavelength showing the maximum absorbance among multiple absorption maxima in the spectroscopic absorption spectrum in the wavelength region of 300 to 460 nm.

The dye compound used in the present invention is not particularly limited as long as it has a maximum absorption wavelength in the wavelength range of 380 to 430 nm. It is more preferable that the maximum absorption wavelength of the absorption spectrum of the dye compound is in the wavelength range of 380 to 420 nm. In the present invention, by using such a dye compound in combination with the ultraviolet absorber, it is possible to sufficiently absorb light in a range (wavelength 380 nm to 430 nm) that does not affect the emission of the organic EL element, and to sufficiently transmit light in the emission range of the organic EL element (wavelength side longer than 430 nm), thereby suppressing deterioration of the organic EL element due to external light. In addition, the dye compound is not particularly limited as long as it has the above-mentioned wavelength characteristics, but it is preferable that the material does not have fluorescent or phosphorescent properties (photoluminescence) so as not to inhibit the display properties of the organic EL element.

The half-width of the dye compound is not particularly limited, but is preferably 80 nm or less, more preferably 5 to 70 nm, and even more preferably 10 to 60 nm. The half-width of the dye compound within the above range is preferable because it enables control so that light in a region that does not affect the light emission of the organic EL element is sufficiently absorbed while light on the longer wavelength side than 430 nm is sufficiently transmitted. The half-width is measured by the method described below.
<Method of measuring half-value width>
The half-width of the dye compound was measured from the transmission absorption spectrum of a solution of the dye compound under the following conditions using an ultraviolet-visible spectrophotometer (U-4100, Hitachi High-Tech Science Corp.). The half-width of the dye compound was determined as the wavelength interval (full width at half maximum) between two points that were 50% of the peak value from the spectrum measured by adjusting the concentration so that the absorbance at the maximum absorption wavelength was 1.0.
(Measurement condition)
Solvent: toluene or chloroform Cell: quartz cell Optical path length: 10 mm

The dye compound may be any compound whose absorption spectrum has a maximum absorption wavelength in the wavelength region of 380 to 430 nm, and its structure, etc., is not particularly limited. Examples of the dye compound include organic dye compounds and inorganic dye compounds, but among these, organic dye compounds are preferred from the viewpoints of maintaining dispersibility in resin components such as base polymers and transparency.

Examples of the organic dye compounds include azomethine compounds, indole compounds, cinnamic acid compounds, pyrimidine compounds, and porphyrin compounds.

As the organic dye compound, commercially available products can be suitably used. Specifically, examples of the indole-based compounds include BONASORB UA3911 (trade name, maximum absorption wavelength in the absorption spectrum: 398 nm, half-width: 48 nm, manufactured by Orient Chemical Industry Co., Ltd.) and BONASORB UA3912 (trade name, maximum absorption wavelength in the absorption spectrum: 386 nm, half-width: 53 nm, manufactured by Orient Chemical Industry Co., Ltd.), examples of the cinnamic acid-based compounds include SOM-5-0106 (trade name, maximum absorption wavelength in the absorption spectrum: 416 nm, half-width: 50 nm, manufactured by Orient Chemical Industry Co., Ltd.), and examples of the porphyrin-based compounds include FDB-001 (trade name, maximum absorption wavelength in the absorption spectrum: 420 nm, half-width: 14 nm, manufactured by Yamada Chemical Industry Co., Ltd.).

The dye compounds may be used alone or in combination of two or more kinds, but the total content is preferably about 0.01 to 10 parts by weight, and more preferably about 0.02 to 5 parts by weight, relative to 100 parts by weight of the monofunctional monomer component forming the (meth)acrylic polymer. By setting the amount of the dye compounds to be added within the above range, light in a region that does not affect the light emission of the organic EL element can be sufficiently absorbed, and the use of an adhesive layer formed from the adhesive composition is preferable because it is possible to suppress deterioration of the organic EL element.

(4) Silane Coupling Agent The pressure-sensitive adhesive composition of the present invention may further contain a silane coupling agent. The amount of the silane coupling agent is preferably 3 parts by weight or less, more preferably 1 part by weight or less, more preferably 0.01 to 1 part by weight, and even more preferably 0.02 to 0.6 parts by weight, based on 100 parts by weight of the monofunctional monomer component forming the (meth)acrylic polymer.

Examples of the silane coupling agent include epoxy group-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, and N-phenyl-γ-aminopropyltrimethoxysilane; (meth)acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; and isocyanate group-containing silane coupling agents such as 3-isocyanatepropyltriethoxysilane.

(5) Crosslinking Agent The pressure-sensitive adhesive composition of the present invention may contain a crosslinking agent. Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, silicone-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, silane-based crosslinking agents, alkyl etherified melamine-based crosslinking agents, metal chelate-based crosslinking agents, and peroxide-based crosslinking agents. The crosslinking agents may be used alone or in combination of two or more. Among these, isocyanate-based crosslinking agents are preferably used.

The above crosslinking agents may be used alone or in combination of two or more. The total content is preferably 5 parts by weight or less, more preferably 0.01 to 5 parts by weight, even more preferably 0.01 to 4 parts by weight, and particularly preferably 0.02 to 3 parts by weight, relative to 100 parts by weight of the monofunctional monomer component that forms the (meth)acrylic polymer.

An isocyanate-based crosslinking agent is a compound that has two or more isocyanate groups (including isocyanate regenerating functional groups in which the isocyanate group is temporarily protected by a blocking agent or oligomerization) in one molecule. Examples of isocyanate-based crosslinking agents include aromatic isocyanates such as tolylene diisocyanate and xylylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

More specifically, for example, lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate, alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate, aromatic diisocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate and polymethylene polyphenyl isocyanate, trimethylolpropane/tolylene diisocyanate trimer adduct (product name: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane/hexamethylene diisocyanate trimer adduct (product name: Examples of such polyisocyanates include isocyanate adducts such as Coronate HL, manufactured by Nippon Polyurethane Industry Co., Ltd., isocyanurate of hexamethylene diisocyanate (product name: Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane adduct of xylylene diisocyanate (product name: D110N, manufactured by Mitsui Chemicals, Inc.), trimethylolpropane adduct of hexamethylene diisocyanate (product name: D160N, manufactured by Mitsui Chemicals, Inc.); polyether polyisocyanates, polyester polyisocyanates, and adducts of these with various polyols, polyisocyanates multifunctionalized with isocyanurate bonds, biuret bonds, allophanate bonds, etc.

(6) Other Additives In addition to the above components, the adhesive composition of the present invention may contain appropriate additives depending on the application. For example, tackifiers (e.g., rosin derivative resins, polyterpene resins, petroleum resins, oil-soluble phenolic resins, etc., which are solid, semi-solid, or liquid at room temperature); fillers such as hollow glass balloons; plasticizers; anti-aging agents; light stabilizers (HALS); antioxidants, etc. are included. Furthermore, it is preferable to contain a rust inhibitor (benzotriazole-based compound, etc.) for the purpose of suppressing corrosion of conductive metals, wiring, etc. These additives are preferably contained in an amount of 1 part by weight or less relative to 100 parts by weight of the monofunctional monomer component.

In the present invention, the adhesive composition is preferably adjusted to a viscosity suitable for application to a substrate. The viscosity of the adhesive composition is adjusted, for example, by adding various polymers such as thickening additives or polyfunctional monomers, or by partially polymerizing the monomer components in the adhesive composition. The partial polymerization may be performed before or after adding various polymers such as thickening additives or polyfunctional monomers. Since the viscosity of the adhesive composition varies depending on the amount of additives, the polymerization rate when the monomer components in the adhesive composition are partially polymerized cannot be uniquely determined, but as a guideline, it is preferably about 20% or less, more preferably about 3 to 20%, and even more preferably about 5 to 15%. If it exceeds 20%, the viscosity becomes too high, making it difficult to apply to a substrate.

2. Pressure-sensitive adhesive layer for organic EL display device The pressure-sensitive adhesive layer for organic EL display device of the present invention is formed from the pressure-sensitive adhesive composition for organic EL display device.

From the viewpoint of ensuring the function of absorbing light having a wavelength of less than 430 nm, the thickness of the adhesive layer of the present invention is preferably 12 μm or more, more preferably 50 μm or more, even more preferably 100 μm or more, and particularly preferably 150 μm or more. The upper limit of the thickness of the adhesive layer is not particularly limited, but is preferably 1 mm or less, more preferably 300 μm or less, and even more preferably 250 μm or less. If the thickness of the adhesive layer exceeds 1 mm, it becomes difficult for ultraviolet light to pass through, and polymerization of the monomer component takes time, and problems arise in processability, winding and transportability in the process, which may result in poor productivity, and is therefore undesirable.

The pressure-sensitive adhesive layer of the present invention has a peak tan δ (Tg) value when dynamic viscoelasticity is measured at a frequency of 1 Hz of -20°C to -5°C, preferably -19°C to -6°C, and more preferably -18°C to -7°C. If the Tg is higher than -5°C, the pressure-sensitive adhesive layer will be hard and lack flexibility, and will not be able to satisfy the peel resistance required when subjected to a drop impact. On the other hand, if the Tg is lower than -20°C, the layer will be too soft, making it difficult to ensure the elastic modulus at high temperatures.

The adhesive layer of the present invention also has a transmittance of 10% or less at a wavelength of 380 nm and a transmittance of 85% or more at a wavelength of 450 nm.

The transmittance of the adhesive layer at a wavelength of 380 nm is preferably 5% or less, and more preferably 2% or less. When the transmittance of the adhesive layer is within the above range, light in an area that does not affect the light emission of the organic EL element can be sufficiently absorbed, and deterioration of the organic EL element can be suppressed.

The transmittance of the adhesive layer at a wavelength of 450 nm is preferably 88% or more, more preferably 89% or more, and even more preferably 90% or more. When the transmittance of the adhesive layer is within the above range, light can be sufficiently transmitted in the light-emitting region of the organic EL element (wavelengths longer than 430 nm), and an organic EL display device using the adhesive layer can emit sufficient light.

Furthermore, by having the above-mentioned transmittance, the pressure-sensitive adhesive layer of the present invention can sufficiently absorb light in a region that does not affect the light emission of the organic EL element, and can sufficiently transmit light in the light-emitting region of the organic EL element (wavelengths longer than 430 nm) , thereby suppressing deterioration of the organic EL element due to external light.

The adhesive layer of the present invention has a total light transmittance of 85% or more. The total light transmittance is preferably 88% or more, more preferably 89% or more, and even more preferably 90% or more. The haze is 0 to 1%, preferably 0.8% or less, and even more preferably 0.6% or less. The total light transmittance and haze being within the above ranges, the adhesive layer has high transparency. Regardless of the thickness of the adhesive layer of the present invention, it is preferable that the total light transmittance and haze satisfy the above ranges, and it is preferable that the thickness of the adhesive layer is 12-250 μm, which satisfies the above range, and it is particularly preferable that the thickness of the adhesive layer is 12 μm to 1 mm, which satisfies the above range.

The pressure-sensitive adhesive layer of the present invention preferably has a relative dielectric constant at a frequency of 100 kHz of 3.5 or less, more preferably 3.3 or less, even more preferably 3.2 or less, and even more preferably 3.0 or less.

The gel fraction of the adhesive layer of the present invention is not particularly limited, but is preferably 50 to 95% by weight. The gel fraction is more preferably 75% or more, and even more preferably 85% or more. By adjusting the gel fraction of the adhesive layer to within the above range, the cohesive force of the adhesive layer can be ensured, which is preferable in terms of processability and handleability.

The adhesive layer of the present invention preferably has a 180-degree peel adhesive strength (peel speed 300 mm/min) of 7 N/20 mm or more against alkali-free glass in terms of preventing peeling of the film in reliability tests and peeling upon impact from being dropped. The adhesive strength is preferably 8 N/20 mm or more, more preferably 10 N/20 mm or more. On the other hand, the adhesive strength is preferably 30 N/20 mm or less, more preferably 28 N/20 mm or less, in terms of adhesion to the blade during processing, making processing difficult, and the resulting adhesive fragments contaminating the process.

The method for forming the pressure-sensitive adhesive layer is not particularly limited, and the pressure-sensitive adhesive layer can be formed by a method commonly used in this field. Specifically, the pressure-sensitive adhesive composition is applied to at least one surface of a substrate, and a coating film formed from the pressure-sensitive adhesive composition is dried to form the pressure-sensitive adhesive layer, or the pressure-sensitive adhesive layer can be formed by irradiating the substrate with active energy rays such as ultraviolet rays.

The substrate is not particularly limited, and various substrates such as release films and transparent resin film substrates, as well as polarizing films described below, can be suitably used as the substrate. A conductive layer for the purpose of preventing static electricity can be provided on the surface and/or back surface of the substrate on which the pressure-sensitive adhesive layer is provided.

The adhesive layer formed on the release film (separator) can also be used as a sheet-like product with a further release film (separator) in the form of release film (separator)/adhesive layer/release film (separator).

Examples of materials that can be used for the release film include resin films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films; porous materials such as paper, cloth, and nonwoven fabrics; nets, foam sheets, metal foils, and laminates of these materials; and other suitable thin materials. Resin films are preferably used because of their excellent surface smoothness.

Examples of such resin films include polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polyethylene terephthalate films, polybutylene terephthalate films, polyurethane films, and ethylene-vinyl acetate copolymer films.

The thickness of the release film is usually 5 to 200 μm, and preferably about 5 to 100 μm. If necessary, the release film can be subjected to a release and antifouling treatment using a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent, silica powder, etc., or an antistatic treatment such as a coating type, kneading type, or deposition type. In particular, by appropriately performing a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the release film, the releasability from the pressure-sensitive adhesive layer can be further improved.

As the transparent resin film substrate, although there is no particular limitation, various resin films having transparency can be used. The resin film is formed of a single layer of film. For example, the material can be polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate, acetate-based resins, polyethersulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, polyolefin-based resins, (meth)acrylic-based resins, polyvinyl chloride-based resins, polyvinylidene chloride-based resins, polystyrene-based resins, polyvinyl alcohol-based resins, polyarylate-based resins, polyphenylene sulfide-based resins, etc. Among these, polyester-based resins, polyimide-based resins, and polyethersulfone-based resins are particularly preferred.

The thickness of the film substrate is preferably 15 to 200 μm, and more preferably 25 to 188 μm.

The method for applying the pressure-sensitive adhesive composition to the substrate is not particularly limited, and any suitable known method may be used, such as roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, or die coating.

When the pressure-sensitive adhesive layer is formed by drying a coating film formed from the pressure-sensitive adhesive composition, the drying conditions (temperature, time) are not particularly limited and can be set appropriately depending on the composition, concentration, etc. of the pressure-sensitive adhesive composition, but are, for example, about 60 to 170°C, preferably 60 to 150°C, for 1 to 60 minutes, preferably 2 to 30 minutes.

When the pressure-sensitive adhesive composition is an ultraviolet-curable pressure-sensitive adhesive composition and a coating film formed from the ultraviolet-curable pressure-sensitive adhesive composition is irradiated with ultraviolet light, the illuminance of the irradiated ultraviolet light is preferably 5 mW/cm ² or more. If the illuminance of the ultraviolet light is less than 5 mW/cm ² , the polymerization reaction time may be long, and the productivity may be poor. The illuminance of the ultraviolet light is preferably 200 mW/cm ² or less. If the illuminance of the ultraviolet light exceeds 200 mW/cm ² , the photopolymerization initiator is rapidly consumed, so that the molecular weight of the polymer may be reduced, and the retention force may be reduced, especially at high temperatures. The integrated light amount of the ultraviolet light is preferably 100 mJ/cm ² to 5000 mJ/cm ² .

The ultraviolet lamp used in the present invention is not particularly limited, but an LED lamp is preferable. LED lamps emit less heat than other ultraviolet lamps, so the temperature during polymerization of the adhesive layer can be suppressed. This prevents the polymer from becoming low molecular weight, prevents a decrease in the cohesive strength of the adhesive layer, and increases the holding power at high temperatures when made into an adhesive sheet. It is also possible to combine multiple ultraviolet lamps. It is also possible to irradiate ultraviolet light intermittently, providing a light period during which ultraviolet light is irradiated and a dark period during which ultraviolet light is not irradiated.

In the present invention, the final polymerization rate of the monomer components in the ultraviolet-curable adhesive composition is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

In the present invention, the peak wavelength of the ultraviolet light irradiated to the ultraviolet-curable adhesive composition is preferably in the range of 200 to 500 nm, and more preferably in the range of 300 to 450 nm. If the peak wavelength of the ultraviolet light exceeds 500 nm, the photopolymerization initiator may not decompose and the polymerization reaction may not start. If the peak wavelength of the ultraviolet light is less than 200 nm, the polymer chain may be broken, resulting in a decrease in adhesive properties.

The reaction is inhibited by oxygen in the air, so in order to block oxygen, it is preferable to form a release film or the like on the coating film formed from the ultraviolet-curable acrylic adhesive composition, or to carry out the photopolymerization reaction in a nitrogen atmosphere. Examples of the release film include those mentioned above. When a release film is used, the release film can be used as it is as a separator for the polarizing film with the adhesive layer.

In addition, when the ultraviolet-curable pressure-sensitive adhesive composition used in the present invention contains a photopolymerization initiator (B), a monomer component containing an alkyl (meth)acrylate and the photopolymerization initiator (B) are
It is preferable to irradiate a composition containing a photopolymerization initiator (sometimes referred to as a "pre-addition polymerization initiator") with ultraviolet light to form a partial polymer of the monomer component, and then add an ultraviolet absorber and a photopolymerization initiator (A) (sometimes referred to as a "post-addition polymerization initiator") having an absorption band at a wavelength of 400 nm or more to the partial polymer of the monomer component to prepare an ultraviolet-curable pressure-sensitive adhesive composition. The polymerization rate of the partial polymer is preferably about 20% or less, more preferably about 3 to 20%, and even more preferably about 5 to 15%. The ultraviolet light irradiation conditions are as described above.

As described above, when forming an adhesive layer from an ultraviolet-curable adhesive composition containing a photopolymerization initiator (B), the polymerization rate of the monomer components can be increased by carrying out the two-stage polymerization as described above, and the ultraviolet absorbing function of the finally produced adhesive layer can be improved.

3. Polarizing Film with Adhesive Layer for Organic EL Display Device The polarizing film with an adhesive layer for organic EL display device of the present invention is characterized by having a polarizing film and the above-mentioned adhesive layer for organic EL display device.

As the adhesive layer for an organic EL display device, the above-mentioned ones can be suitably used. Furthermore, when the adhesive layer is formed on a substrate other than a polarizing film, the adhesive layer can be transferred by being attached to the polarizing film. Furthermore, the release film can be used as it is as a separator for the polarizing film with the adhesive layer, which can simplify the process.

The polarizing film is not particularly limited, but may be one having a polarizer and a transparent protective film on at least one side of the polarizer.

(1) Polarizer The polarizer is not particularly limited, and various polarizers can be used. Examples of polarizers include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene-vinyl acetate copolymer films, which are uniaxially stretched after adsorbing a dichroic substance such as iodine or a dichroic dye, and polyene-based oriented films such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride. Among these, polarizers made of a polyvinyl alcohol film and a dichroic substance such as iodine are suitable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and stretching it uniaxially can be produced, for example, by immersing the polyvinyl alcohol-based film in an aqueous solution of iodine to dye it and stretching it to 3 to 7 times its original length. If necessary, it can also be immersed in an aqueous solution of potassium iodide or the like which may contain boric acid, zinc sulfate, zinc chloride, or the like. Furthermore, if necessary, the polyvinyl alcohol-based film can be immersed in water and washed before dyeing. Washing the polyvinyl alcohol-based film with water can wash off dirt and blocking inhibitors on the surface of the polyvinyl alcohol-based film, and also has the effect of preventing unevenness such as uneven dyeing by swelling the polyvinyl alcohol-based film. Stretching can be performed after dyeing with iodine, or it can be stretched while dyeing, or it can be dyed with iodine after stretching. Stretching can be performed in an aqueous solution of boric acid, potassium iodide, or the like, or in a water bath.

In addition, in the present invention, a thin polarizer having a thickness of 10 μm or less can also be used. From the viewpoint of thinning, the thickness is preferably 1 to 7 μm. Such a thin polarizer has little thickness unevenness, excellent visibility, and excellent durability due to little dimensional change, and is also preferable in that the thickness of the polarizing film can be made thin.

Representative examples of thin polarizers include the thin polarizing films described in JP-A-51-069644, JP-A-2000-338329, WO-A-2010/100917, WO-A-2010/100917, or Japanese Patent No. 4751481 and JP-A-2012-073563. These thin polarizing films can be obtained by a manufacturing method including a step of stretching a polyvinyl alcohol-based resin (hereinafter also referred to as PVA-based resin) layer and a resin substrate for stretching in a laminated state, and a step of dyeing. With this manufacturing method, even if the PVA-based resin layer is thin, it can be stretched without problems such as breakage due to stretching because it is supported by the resin substrate for stretching.

As the thin polarizing film, among the manufacturing methods including the steps of stretching and dyeing the laminate, those obtained by a manufacturing method including a step of stretching in an aqueous boric acid solution as described in WO 2010/100917, WO 2010/100917, or Japanese Patent No. 4751481 and JP 2012-073563 are preferred, because they can be stretched at a high ratio and have improved polarization performance. In particular, those obtained by a manufacturing method including a step of auxiliary air-stretching before stretching in an aqueous boric acid solution as described in Japanese Patent No. 4751481 and JP 2012-073563 are preferred.

(2) Transparent protective film As for the transparent protective film, a conventionally used one can be appropriately used. Specifically, a transparent protective film formed from a material excellent in transparency, mechanical strength, thermal stability, moisture blocking property, isotropy, etc. is preferable, and examples thereof include polyester-based polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose-based polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers such as polymethyl methacrylate, styrene-based polymers such as polystyrene and acrylonitrile-styrene copolymer (AS resin), polycarbonate-based polymers, etc. Examples of the polymer forming the transparent protective film include polyethylene, polypropylene, polyolefins having a cyclo- or norbornene structure, polyolefin-based polymers such as ethylene-propylene copolymers, vinyl chloride-based polymers, amide-based polymers such as nylon and aromatic polyamides, imide-based polymers, sulfone-based polymers, polyethersulfone-based polymers, polyetheretherketone-based polymers, polyphenylene sulfide-based polymers, vinyl alcohol-based polymers, vinylidene chloride-based polymers, vinyl butyral-based polymers, arylate-based polymers, polyoxymethylene-based polymers, epoxy-based polymers, and blends of the above polymers. The transparent protective film can also be formed as a cured layer of a thermosetting or ultraviolet-curing resin such as an acrylic, urethane, acrylic urethane, epoxy, or silicone.

The thickness of the transparent protective film can be determined as appropriate, but is generally about 1 to 500 μm, taking into consideration strength, ease of handling, thinness, etc.

The polarizer and the transparent protective film are preferably adhered to each other via a water-based adhesive or the like. Examples of water-based adhesives include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl latex-based adhesives, water-based polyurethanes, water-based polyesters, and the like. In addition to the above, examples of adhesives between the polarizer and the transparent protective film include ultraviolet-curing adhesives and electron beam-curing adhesives. Electron beam-curing polarizing film adhesives exhibit suitable adhesion to the various types of viewing-side transparent protective films described above. The adhesive used in the present invention may also contain a metal compound filler.

The surface of the transparent protective film to which the polarizer is not attached may be provided with a hard coat layer, anti-reflection treatment, anti-sticking treatment, or treatment for diffusion or anti-glare purposes.

In addition, any of the transparent protective films that have a phase difference and can function as an optical compensation layer can be used as the transparent protective film. When a transparent protective film having a phase difference is used, the phase difference characteristics can be appropriately adjusted to a value required for optical compensation. As such a phase difference film, a stretched film can be suitably used. The phase difference film is selected and used according to various applications from those that satisfy the following relationships: nx = ny > nz, nx > ny > nz, nx > ny = nz, nx > nz > ny, nz = nx > ny, nz > nx > ny, and nz > nx = ny, where nx is the refractive index in the slow axis direction, ny is the refractive index in the in-plane fast axis direction, and nz is the refractive index in the thickness direction. Note that nx = ny includes not only the case where nx and ny are completely identical, but also the case where nx and ny are substantially the same. In addition, ny = nz includes not only the case where ny and nz are completely identical, but also the case where ny and nz are substantially the same.

When the polarizing film used in the present invention is used as a circular polarizing plate for preventing reflection in an organic EL display device, the retardation film is preferably a 1/4 wavelength plate in which the front retardation of the transparent protective film is 1/4 wavelength (approximately 100 to 170 nm).

When a retardation film is used as the transparent protective film, it is preferable to use one having a transparent protective film on one side of a polarizer and a retardation film on the other side. In this case, the location of the pressure-sensitive adhesive layer is not particularly limited, and it may be provided on the side of the transparent protective film opposite to the side in contact with the polarizer, or on the side of the retardation film opposite to the side in contact with the polarizer. However, from the viewpoint of suppressing deterioration of the organic EL element, it is preferable that the pressure-sensitive adhesive layer is provided on at least one side or both sides.

An example of a specific configuration of the polarizing film with an adhesive layer for an organic EL display device of the present invention is shown in Figures 1(a) to (c). As shown in Figure 1(a), the adhesive layer 2/transparent protective film 3/polarizer 4/retardation film 5; as shown in Figure 1(b), the transparent protective film 3/polarizer 4/retardation film 5/adhesive layer 2; as shown in Figure 1(c), the adhesive layer 2/transparent protective film 3/polarizer 4/retardation film 5/adhesive layer 2; the adhesive layer 2; the adhesive layer 2; the transparent protective film 3/polarizer 4/retardation film 5/adhesive layer 2; the adhesive ... In addition, in FIG. 1, the polarizing film 6 is a single-protected polarizing film composed of a polarizer 4 and a transparent protective film 3, but this is not limited thereto, and it may be a double-protected polarizing film having a transparent protective film between the polarizer 4 and the retardation film 5. Also, as described above, various functional layers such as a hard coat layer can be formed on the surface of the transparent protective film 3 that is not in contact with the polarizer 4.

In addition, when the retardation film is laminated on the polarizer via a pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer may be the pressure-sensitive adhesive layer for an organic EL display device of the present invention. That is, the pressure-sensitive adhesive layer-attached polarizing film for an organic EL display device has a first pressure-sensitive adhesive layer, a transparent protective film, a polarizer, a second pressure-sensitive adhesive layer, a retardation film, and a third pressure-sensitive adhesive layer in this order,
At least one of the first pressure-sensitive adhesive layer, the second pressure-sensitive adhesive layer, and the third pressure-sensitive adhesive layer may be the pressure-sensitive adhesive layer for an organic EL display device.

4. Organic EL Display Device The organic EL display device of the present invention is characterized by using at least one pressure-sensitive adhesive layer for an organic EL display device of the present invention and/or at least one polarizing film with a pressure-sensitive adhesive layer for an organic EL display device of the present invention.

As an example of a specific configuration of an organic EL display device, for example, as shown in Figures 2 and 3, there can be mentioned an organic EL display device in which each layer is laminated in the following order: cover glass or cover plastic 7/adhesive layer 2b/transparent protective film 3/polarizer 4/retardation film 5/adhesive layer 2a/organic EL display panel (OLED element panel) 8 (Figure 2); or cover glass or cover plastic 7/adhesive layer 9/transparent protective film 3/polarizer 4/retardation film 5/adhesive layer 2a/organic EL display panel 8 (Figure 3).

The organic EL display device can also be used as an organic EL display device with a touch panel, which further has a touch panel having at least one sensor film. For example, as shown in FIG. 4, an organic EL display device can be used in which the layers are laminated in this order: cover glass or cover plastic 7/adhesive layer 2c/sensor film 10/adhesive layer 2b/transparent protective film 3/polarizer 4/retardation film 5/adhesive layer 2a/organic EL display panel 8 (FIG. 4).

At least one of the adhesive layers 2 in each of the above configurations may be the adhesive layer of the present invention, and all of the adhesive layers 2 may be the adhesive layers of the present invention. The organic EL display device of the present invention may also include various functional layers such as a protective film and a hard coat layer in addition to the above. In addition, adhesive layers and/or adhesive layers can be used as appropriate in laminating each layer. As adhesive layers other than the adhesive layer of the present invention, ordinary adhesive layers used in this field can be used as appropriate.

The adhesive layer for an organic EL display device of the present invention is preferably applied to an organic EL display device with a touch panel, which has an organic EL panel, a circularly polarizing film arranged in order from the viewing side of the organic EL panel, and a touch panel having at least one sensor film, as shown in FIG. 4. In particular, the adhesive layer for an organic EL display device of the present invention is preferably applied when it is arranged on the viewing side of the circularly polarizing film and in contact with at least one sensor film forming the touch panel. In FIG. 4, the adhesive layer for an organic EL display device of the present invention is preferably applied as the adhesive layer 2c and/or adhesive layer 2b in contact with the sensor film 10, and is particularly preferably used as the adhesive layer 2b. The adhesive layer 2b may be applied as a polarizing film with an adhesive layer as shown in FIG. 1(a), or as an adhesive layer between the sensor film and the circularly polarizing film.

In addition, in FIG. 4, the adhesive layer for an organic EL display device of the present invention is also preferably applied when two or more sensor films 10 are used. For example, in the configuration of cover glass or cover plastic 7/adhesive layer 2c/sensor film 10/adhesive layer 2b'/sensor film 10'/adhesive layer 2b/transparent protective film 3/polarizer 4/retardation film 5/adhesive layer 2a/organic EL display panel 8, in addition to adhesive layer 2c and/or adhesive layer 2b, adhesive layer 2b' is also preferably applied as the adhesive layer for an organic EL display device of the present invention.

The sensor film 10 in FIG. 4 is a capacitive touch sensor (film), which is a transparent conductive film in which a transparent conductive layer is provided on a glass plate or a transparent plastic film (particularly a PET film). The adhesive layer for an organic EL display device comes into contact with the sensor film means that it comes into contact with the transparent conductive layer.

Examples of the transparent conductive layer include a thin film of ITO (indium tin oxide), ZnO, SnO, or CTO (cadmium tin oxide). Other transparent conductive layers can be made of silver, copper, CNT (carbon nanotube), or the like. Metal mesh sensors such as Ag nanowires and Ag/Cu can also be used as the transparent conductive layer. In addition, in FIG. 4, a capacitive touch panel using at least one sensor film 10 can also have wiring formed of thin copper or silver paste at the end of the sensor film.

As described above, the adhesive layer for an organic EL display device of the present invention can be used as an adhesive layer that is used to be in contact with at least one sensor film in a touch panel of an organic EL display device having the above configuration, and can also be used as an adhesive layer for a touch panel that is used to be in contact with at least one sensor film in a touch panel, not limited to organic EL display devices.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Note that all parts and percentages in each example are by weight.

Example 1
(Preparation of Acrylic Pressure-Sensitive Adhesive Composition)
A monomer mixture consisting of 49 parts by weight of 2-ethylhexyl acrylate (2EHA), 30 parts by weight of isostearyl acrylate (ISTA), 18 parts by weight of N-vinyl-2-pyrrolidone (NVP), and 3 parts by weight of 4-hydroxybutyl acrylate (4HBA) was mixed with 1-hydroxycyclohexyl phenyl ketone (product name: Irgacure 184, having an absorption band at wavelengths of 200 to 370 nm, manufactured by BASF Corporation) as a photopolymerization initiator. Then, 0.035 parts by weight of 2,2-dimethoxy-1,2-diphenylethan-1-one (trade name: Irgacure 651, having an absorption band at wavelengths of 200 to 380 nm, manufactured by BASF Corporation) were mixed, and the mixture was irradiated with ultraviolet light until the viscosity (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30° C.) reached about 20 Pa s, thereby obtaining a prepolymer composition (polymerization rate: 9%) in which a portion of the monomer mixture was polymerized. Next, 0.065 parts by weight of hexanediol diacrylate (HDDA), 0.3 parts by weight of a silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.), 0.8 parts by weight (solid content weight) of 2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (trade name: Tinosorb S ultraviolet absorber (a)" manufactured by BASF Japan Ltd.) dissolved in a monomer mixture of the same ratio as above to a solid content of 10%, and 0.10 parts by weight of bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (trade name: Irgacure 819, manufactured by BASF Japan Ltd.) were added to the prepolymer composition relative to 100 parts by weight of the monofunctional monomer component in the obtained acrylic pressure-sensitive adhesive composition, and the mixture was stirred to obtain an acrylic pressure-sensitive adhesive composition.

(Formation of Pressure-Sensitive Adhesive Layer)
The acrylic adhesive composition was applied onto a release-treated film of a release film so that the thickness of the adhesive layer after formation was 100 μm, and then a release film was attached to the surface of the adhesive composition layer. Thereafter, the adhesive composition layer was photocured by irradiating it with ultraviolet light under the conditions of illuminance: 6.5 mW/cm ² , light amount: 1500 mJ/cm ² , and peak wavelength: 350 nm to form an adhesive layer.

Examples 2 to 4 and Comparative Examples 1 to 3
An acrylic pressure-sensitive adhesive composition was prepared in the same manner as in Example 1, except that the type and amount of each component in the preparation of the acrylic pressure-sensitive adhesive composition was changed as shown in Table 1. In addition, a pressure-sensitive adhesive layer was formed using the acrylic pressure-sensitive adhesive composition in the same manner as in Example 1, except that the thickness of the pressure-sensitive adhesive layer was changed as shown in Table 1.

(Production of Polarizing Film (P))
A cycloolefin polymer (COP) film having a thickness of 25 μm was attached to the viewing side of a polarizer made of a 5 μm-thick stretched polyvinyl alcohol film impregnated with iodine using a polyvinyl alcohol-based adhesive, and a retardation film (thickness: 56 μm, material: polycarbonate) was laminated to the organic EL display panel side surface of the polarizer using a polyvinyl alcohol-based adhesive to obtain a polarizing film (P). The polarization degree of the polarizing film was 99.995%.

(Production of polarizing film with adhesive layer)
The pressure-sensitive adhesive layer obtained in the Examples or Comparative Examples was laminated on the viewing side of the polarizing film (P) (i.e., the surface of the 25 μm-thick cycloolefin polymer (COP) film) to form a polarizing film with a pressure-sensitive adhesive layer.

The following evaluations were carried out on the adhesive layers and polarizing films with adhesive layers obtained in the Examples and Comparative Examples. The results are shown in Table 1.

<Measurement of Tg of Pressure-Sensitive Adhesive Layer by Dynamic Viscoelasticity>
The pressure-sensitive adhesive layers obtained in the Examples and Comparative Examples were laminated to obtain a pressure-sensitive adhesive laminate layer having a thickness of about 2 mm. The pressure-sensitive adhesive laminate layer was punched out into a disk shape having a diameter of 7.9 mm, which was sandwiched and fixed between parallel plates, and the loss modulus G'' and storage modulus G' were measured under the measurement conditions described below using a dynamic viscoelasticity measuring device (ARES, manufactured by Rheometrics). The peak value of the ratio of the loss modulus to the storage modulus (G''/G') = Tan δ was read as the Tg of the pressure-sensitive adhesive layer.
Measurement: Shear mode Temperature range: -50°C to 150°C
Heating rate: 5°C/min
Frequency: 1Hz
The storage elastic modulus G' (25°C) is preferably 5.0 x 10 ⁴ Pa or more and 2.5 x 10 ⁵ Pa or less. The storage elastic modulus G' (80°C) is preferably 1.2 x 10 ⁴ Pa or more and 1.0 x 10 ⁵ Pa or less. The storage elastic modulus G' (25°C) of 5.0 x 10 ⁴ Pa or more is preferable in terms of ensuring the processability during punching, and the storage elastic modulus G' (25°C) of 2.5 x 10 ⁵ Pa or less is preferable in terms of ensuring the conformability to the printing step of the decorative printing of the cover glass or the like. The storage elastic modulus G' (80°C) of 1.2 x 10 ⁴ Pa or more is preferable in terms of suppressing peeling of the film or the like when put into high temperature reliability, and the storage elastic modulus G' (80°C) of 1.0 x 10 ⁵ Pa or less is preferable in terms of removing air bubbles generated by lamination during autoclave (pressure defoaming) treatment.

<Measurement of transmittance and hue of adhesive layer containing dye compound and UV absorber>
From the adhesive layer obtained in the Examples or Comparative Examples, one release film was peeled off and attached to a slide glass (product name: White Polishing No. 1, thickness: 0.8-1.0 mm, total light transmittance: 92%, haze: 0.2%, manufactured by Matsunami Glass Industry Co., Ltd.). The other release film was peeled off and the same slide glass was attached, and a test piece having a layer structure of slide glass/adhesive layer/slide glass was prepared through autoclave treatment (50°C, 0.5 MPa, 15 minutes). The prepared test piece was measured with a spectrophotometer (product name: U4100, manufactured by Hitachi High-Technologies Corporation). The transmittance was measured in the wavelength range of 350 nm to 780 nm. The transmittance at wavelengths of 380 nm and 450 nm is shown in Table 1.

<Total light transmittance, haze>
One release film was peeled off from the adhesive layer obtained in the Examples or Comparative Examples, and the adhesive layer was attached to a slide glass (product name: White Polish No. 1, thickness: 0.8 to 1.0 mm, total light transmittance: 92%, haze: 0.2%, manufactured by Matsunami Glass Industry Co., Ltd.). The other release film was peeled off to prepare a test piece having a layer structure of adhesive layer/slide glass. The total light transmittance and haze value in the visible light region of the test piece were measured using a haze meter (device name: HM-150, manufactured by Murakami Color Research Institute Co., Ltd.).

<Dielectric constant evaluation>
The pressure-sensitive adhesive layer (the silicone-treated PET film was peeled off from the pressure-sensitive adhesive sheet) obtained in the Examples or Comparative Examples was sandwiched between a copper foil and an electrode, and the dielectric constant at a frequency of 100 kHz was measured using the following device. Three samples were prepared for the measurement, and the average of the measured values for the three samples was taken as the dielectric constant.
The relative dielectric constant of the pressure-sensitive adhesive layer at a frequency of 100 kHz was measured in accordance with JIS K 6911 under the following conditions.
Measurement method: capacitance method (apparatus: Agilent Technologies 4294A Precision Impedance Analyzer)
Electrode configuration: 12.1 mm diameter, 0.5 mm thick aluminum plate Counter electrode: 3 oz copper plate Measurement environment: 23 ± 1 ° C, 52 ± 1% RH

<Measurement of Gel Fraction>
A predetermined amount (initial weight W1) was taken from the adhesive layer obtained in each Example or Comparative Example, immersed in an ethyl acetate solution, and left at room temperature for one week. After that, the insoluble matter was removed and the dried weight (W2) was measured and calculated as follows:
Gel fraction (%)=(W2/W1)×100

<Adhesiveness>
A sheet piece having a length of 100 mm and a width of 20 mm was cut out from the adhesive layer obtained in the Examples or Comparative Examples. Next, one release film of the adhesive layer was peeled off, and a PET film (trade name: Lumirror S-10, thickness: 25 μm, manufactured by Toray Industries, Inc.) was attached (backed). Next, the other release film was peeled off, and the test plate was pressed onto a glass plate (trade name: Soda Lime Glass #0050, manufactured by Matsunami Glass Industry Co., Ltd.) using a 2 kg roller and pressure bonding under pressure bonding conditions of one round trip to prepare a sample consisting of test plate/adhesive layer/PET film. The obtained sample was autoclaved (50° C., 0.5 MPa, 15 minutes), and then allowed to cool for 30 minutes under an atmosphere of 23° C. and 50% RH. After cooling, the pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer/PET film) was peeled off from the test plate using a tensile tester (apparatus name: Autograph AG-IS, manufactured by Shimadzu Corporation) in accordance with JIS Z0237 under conditions of an atmosphere of 23° C. and 50% RH, a pulling speed of 300 mm/min, and a peel angle of 180°, and the 180° peel adhesion strength (N/20 mm) was measured.

<Drop impact resistance test>
A cycloolefin polymer (COP) film (thickness 55 μm) having a conductive ITO layer on one side was attached to the entire surface of one side of chemically strengthened glass (length 100 mm, width 100 mm, thickness 1.3 mm) via an acrylic adhesive layer of the same size and thickness 25 μm. Furthermore, the adhesive layer prepared in the examples and comparative examples was cut to a size of length 50 mm and width 50 mm, and laminated so that the center of the adhesive layer overlaps with the center of the ITO layer side of the COP film with the conductive ITO layer, and then the center of a black acrylic plate (length 110 mm, width 120 mm, thickness 1 mm) was attached to the center to prepare a test piece (chemically strengthened glass / adhesive layer / COP film with conductive ITO layer (thickness 55 μm) / adhesive layer of the example or comparative example / acrylic plate). The obtained test piece was autoclaved (50°C, 0.5 MPa, 15 minutes), and then cooled for 24 hours under an atmosphere of 23°C and 50% R.H. The test piece thus prepared was fixed on both sides of the acrylic plate to a horizontally placed base so that the length and width were vertical. Meanwhile, a fulcrum was set above the test piece (53 cm above the center of the test piece), and one end of a 53 cm long string was fixed to the fulcrum, and a 113 g lead ball was fixed to the other end.
The drop impact resistance test was performed by dropping the lead ball from the same height as the fulcrum in a pendulum manner to collide with the acrylic plate side (the center of the vertical and horizontal planes) of the fixed test piece. The peeling distance was measured after 20 collisions. The peeling distance was the distance at which peeling was observed from the edge or corner of the adhesive layer of the example or comparative example of the test piece. The maximum peeling distance of 5 mm or less was considered to be acceptable.

In Table 1,
2EHA is 2-ethylhexyl acrylate;
ISTA is isostearyl acrylate;
NVP is N-vinyl-2-pyrrolidone;
4HBA is 4-hydroxybutyl acrylate;
HEA is 2-hydroxyethyl acrylate;
HDDA is hexanediol diacrylate;
DPHA is dipentaerythritol hexaacrylate;
TMPTA is trimethylolpropane triacrylate;
The ultraviolet absorber a is 2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (trade name: Tinosorb S, maximum absorption wavelength of the absorption spectrum: 346 nm, manufactured by BASF Japan Ltd.);
The ultraviolet absorber b is 2-(2H-benzotriazol-2-yl)-6-(1-methyl-1-phenylethyl)-4-(1,1,3,3-tetramethylbutyl)phenol (trade name: Tinuvin 928, maximum absorption wavelength of the absorption spectrum: 349 nm, manufactured by BASF Japan Ltd.);
Dye compound c is BONASORB UA3911 (trade name, indole compound, maximum absorption wavelength of absorption spectrum: 398 nm, half width: 48 nm, manufactured by Orient Chemical Industry Co., Ltd.);
Irg819 is bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (trade name: Irgacure 819, manufactured by BASF Japan);
KBM-403 indicates a silane coupling agent (product name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.).

1 Polarizing film with adhesive layer for organic EL display device 2 Adhesive layer (a, b, c)
3 Transparent protective film 4 Polarizer 5 Retardation film 6 Polarizing film 7 Cover glass or cover plastic 8 Organic EL panel 9 Adhesive layer 10 Sensor film

Claims (22)

A pressure-sensitive adhesive layer for an organic electroluminescence display device, which is formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer and an ultraviolet absorber,
The (meth)acrylic polymer is obtained by polymerizing a monomer component including a monofunctional monomer component including an alkyl(meth)acrylate (A) having an alkyl group having 8 or less carbon atoms at an ester terminal and an alkyl(meth)acrylate (B) having an alkyl group having 12 to 24 carbon atoms at an ester terminal,
the ultraviolet absorber is at least one selected from the group consisting of triazine-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, oxybenzophenone-based ultraviolet absorbers, salicylic acid ester-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers, and is contained in an amount of 0.1 to 5 parts by weight per 100 parts by weight of a monofunctional monomer component forming a (meth)acrylic polymer;
a ratio (a: weight %) of the alkyl (meth)acrylate (A) and a ratio (b: weight %) of the alkyl (meth)acrylate (B) in 100 weight % of the monofunctional monomer component satisfy the following formulas (1) and (2):
Formula (1): 60≦{(a)+(b)}
Formula (2): 1.4≦{(a)/(b)}≦2
And the pressure-sensitive adhesive layer is
The peak value of tan δ (Tg) when dynamic viscoelasticity is measured at a frequency of 1 Hz is −20 to −5° C.;
The transmittance at a wavelength of 380 nm is 10% or less, and the transmittance at a wavelength of 450 nm is 85% or more,
A pressure-sensitive adhesive layer for an organic electroluminescence display device, characterized in that the layer has a total light transmittance of 85% or more and a haze of 1% or less. A pressure-sensitive adhesive layer for an organic electroluminescence display device, which is formed from a pressure-sensitive adhesive composition containing a (meth)acrylic polymer and an ultraviolet absorber,
The (meth)acrylic polymer is obtained by polymerizing a monomer component including a monofunctional monomer component that includes an alkyl(meth)acrylate (A) having an alkyl group having 8 or less carbon atoms at an ester terminal and an alkyl(meth)acrylate (B) having an alkyl group having 12 to 24 carbon atoms at an ester terminal, and that includes at least one polyfunctional monomer selected from the group consisting of trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, and dipentaerythritol hexa(meth)acrylate;
a ratio (a: weight %) of the alkyl (meth)acrylate (A) and a ratio (b: weight %) of the alkyl (meth)acrylate (B) in 100 weight % of the monofunctional monomer component satisfy the following formulas (1) and (2):
Formula (1): 60≦{(a)+(b)}
Formula (2): 1.4≦{(a)/(b)}≦2
And the pressure-sensitive adhesive layer is
The peak value of tan δ (Tg) when dynamic viscoelasticity is measured at a frequency of 1 Hz is −20 to −5° C.;
The transmittance at a wavelength of 380 nm is 10% or less, and the transmittance at a wavelength of 450 nm is 85% or more,
A pressure-sensitive adhesive layer for an organic electroluminescence display device, characterized in that the layer has a total light transmittance of 85% or more and a haze of 1% or less. 3. The pressure-sensitive adhesive layer for an organic EL display device according to claim 1, wherein the maximum absorption wavelength of the absorption spectrum of the ultraviolet absorber is in the wavelength region of 300 to 400 nm. 3. The pressure-sensitive adhesive layer for an organic EL display device according to claim 1, wherein the monofunctional monomer component further comprises at least one cohesive monomer selected from the group consisting of cyclic nitrogen-containing monomers and alicyclic structure-containing monomers. 5. The pressure-sensitive adhesive layer for an organic electroluminescence display device according to claim 4 , wherein the ratio of the cohesive monomer in the monofunctional monomer component is 10 to 22% by weight. The pressure-sensitive adhesive layer for an organic electroluminescence display device according to any one of claims 1 to 5 , wherein the monofunctional monomer component further contains a hydroxyl group-containing monomer. 7. The pressure-sensitive adhesive layer for an organic electroluminescence display device according to claim 6 , wherein the ratio of the hydroxyl group-containing monomer in the monofunctional monomer component is 1.5 to 10% by weight. 3. The pressure-sensitive adhesive layer for an organic electroluminescence display device according to claim 2 , wherein the polyfunctional monomer is contained in an amount of 3 parts by weight or less based on 100 parts by weight of the monofunctional monomer component. The pressure-sensitive adhesive layer for an organic electroluminescence display device according to any one of claims 1 to 8 , characterized in that the pressure-sensitive adhesive composition further contains a dye compound having a maximum absorption wavelength in an absorption spectrum in a wavelength region of 380 to 430 nm. The pressure-sensitive adhesive layer for an organic electroluminescence display device according to any one of claims 1 to 9 , characterized in that the pressure-sensitive adhesive composition further contains 3 parts by weight or less of a silane coupling agent based on 100 parts by weight of the monofunctional monomer component. The pressure-sensitive adhesive layer for an organic electroluminescence display device according to any one of claims 1 to 10 , characterized in that the pressure-sensitive adhesive composition further contains 3 parts by weight or less of a crosslinking agent based on 100 parts by weight of the monofunctional monomer component. The pressure-sensitive adhesive layer for an organic EL display device according to any one of claims 1 to 11 , wherein the pressure-sensitive adhesive composition further contains a photopolymerization initiator. The pressure-sensitive adhesive layer for an organic EL display device according to any one of claims 1 to 12 , characterized in that the pressure-sensitive adhesive layer has a relative dielectric constant of 3.5 or less at a frequency of 100 kHz. The adhesive layer for an organic EL display device according to any one of claims 1 to 13, characterized in that the adhesive layer has a 180-degree peel adhesion strength (peel speed 300 mm/min) to non-alkali glass of 7 N/20 mm or more. The adhesive layer for an organic EL display device according to any one of claims 1 to 14, characterized in that it has a separator on at least one side. A polarizing film with an adhesive layer for an organic EL display device, comprising a polarizing film and an adhesive layer for an organic EL display device according to any one of claims 1 to 15. The polarizing film with an adhesive layer for an organic EL display device according to claim 16, characterized in that the polarizing film has a transparent protective film on one side of a polarizer and a retardation film on the other side, and the adhesive layer for an organic EL display device is provided on the side of the retardation film opposite to the side in contact with the polarizer and/or the side of the transparent protective film opposite to the side in contact with the polarizer. A polarizing film with a pressure-sensitive adhesive layer, comprising a first pressure-sensitive adhesive layer, a transparent protective film, a polarizer, a second pressure-sensitive adhesive layer, a retardation film, and a third pressure-sensitive adhesive layer in this order,
17. The polarizing film with an adhesive layer for an organic electroluminescence display device according to claim 16, wherein at least one of the first adhesive layer, the second adhesive layer, and the third adhesive layer is the adhesive layer for the organic electroluminescence display device. The polarizing film with an adhesive layer for an organic EL display device according to claim 17 or 18, characterized in that the retardation film is a quarter-wave plate and the polarizing film is a circular polarizing film. An organic EL display device comprising at least one pressure-sensitive adhesive layer for an organic EL display device according to any one of claims 1 to 14, or at least one polarizing film with a pressure-sensitive adhesive layer for an organic EL display device according to any one of claims 16 to 19. The organic EL display device is a touch panel-equipped organic EL display device including an organic EL panel, a circularly polarizing film provided in this order from a viewing side of the organic EL panel, and a touch panel having at least one sensor film,
The organic EL display device according to claim 20, characterized in that the pressure-sensitive adhesive layer for an organic EL display device according to any one of claims 1 to 14 is provided on the viewing side of the circularly polarizing film in contact with at least one sensor film. The adhesive layer for an organic EL display device according to any one of claims 1 to 15, which is used to be in contact with at least one sensor film in the touch panel of the organic EL display device according to claim 21.