WO2022045131A1

WO2022045131A1 - Adhesive agent composition, photocurable adhesive agent layer, and photocurable adhesive sheet

Info

Publication number: WO2022045131A1
Application number: PCT/JP2021/030989
Authority: WO
Inventors: 量子浅井; 武史仲野
Original assignee: 日東電工株式会社
Priority date: 2020-08-28
Filing date: 2021-08-24
Publication date: 2022-03-03
Also published as: TW202219227A; KR20230057442A; CN115989143A

Abstract

The purpose of the present invention is to provide an adhesive agent composition, an adhesive agent layer, and an adhesive sheet which exhibit superior conformability and workability, and are suited for producing emissive display devices such as mini/micro LED display devices which have an improved contrast and a function for preventing reflection from metallic wiring and the like. The present invention provides: an adhesive agent composition comprising a colorant and a polymer (A) having a benzophenone structure in a side chain thereof, or comprising a colorant and a mixture of monomer components that constitute the polymer (A) having a benzophenone structure in a side chain thereof or a partial polymer of the mixture of monomer components that constitute the polymer (A) having a benzophenone structure in a side chain thereof, wherein the maximum value for the transmittance of wavelengths in the range of 200-400 nm is greater than the maximum value for the transmittance of wavelengths in the range of 400-700 nm; a photocurable adhesive agent layer which is an adhesive agent layer formed from the cured product of the adhesive agent composition, wherein the cured product retains the benzophenone structure of the polymer (A) having a benzophenone structure in a side chain thereof; and a photocurable adhesive sheet that has the photocurable adhesive agent layer.

Description

Adhesive composition, photocurable adhesive layer, and photocurable adhesive sheet

The present invention relates to a pressure-sensitive adhesive composition, a photo-curable pressure-sensitive adhesive layer, and a photo-curable pressure-sensitive adhesive sheet. More specifically, the present invention relates to a pressure-sensitive adhesive composition suitable for sealing a light emitting element of a self-luminous display device such as a mini / micro LED, a photocurable pressure-sensitive adhesive layer, and a photo-curable pressure-sensitive adhesive sheet.

In recent years, as a next-generation display device, a self-luminous display device represented by a mini / micro LED display device (Mini / Micro Light Emitting Diode Display) has been devised. As a basic configuration of a mini / micro LED display device, a substrate in which a large number of minute LED light emitting elements (LED chips) are arranged at high density is used as a display panel, and the LED chips are sealed with a sealing material. A cover member such as a resin film or a glass plate is laminated on the outermost layer.

There are several self-luminous display devices such as mini / micro LED display devices, such as a white backlight system, a white emission color filter system, and an RGB system. The white emission color filter system and the RGB system are sealed. A black-colored pressure-sensitive adhesive may be used as the material (see, for example, Patent Documents 1 to 3).
The black adhesive contributes to color mixing prevention and contrast improvement by filling the space between the RGB LED chips arranged on the display panel substrate, and also contributes to the prevention of color mixing and the improvement of contrast, and also the metal wiring and ITO arranged on the display panel substrate. This is because it is possible to prevent reflection of metal oxides and the like.

In mini / micro LED display devices, LED chips are densely spread on the substrate, and there are many fine steps in the gaps between the LED chips, which can be used as a sealing material for mini / micro LED display devices. Is required to have the ability to fill these steps, that is, excellent step absorption (also referred to as "step followability"). Therefore, the black pressure-sensitive adhesive needs to be designed to exhibit high fluidity in order to improve step absorption.

On the other hand, although the adhesive showing high fluidity is excellent in step absorption, there is a problem that processability such as shape stability and handleability is deteriorated. For example, in a laminate having a pressure-sensitive adhesive layer showing high fluidity, adhesive chipping occurs during cutting, and the pressure-sensitive adhesive layer tends to protrude or sag from the edges during storage, and foreign matter adheres to the protruding pressure-sensitive adhesive layer. This may cause problems such as process contamination.

A photocurable pressure-sensitive adhesive (hybrid pressure-sensitive adhesive) is known as a pressure-sensitive adhesive that achieves both step absorption and processability (see, for example, Patent Document 4). With hybrid adhesives, it is possible to first make a semi-cured state with high fluidity and excellent step absorption so that it sufficiently follows the step, and then irradiate light to complete the curing and improve workability. Has advantages.

JP-A-2019-204905 Japanese Unexamined Patent Publication No. 2017-203810 Japanese Patent Publication No. 2018-523854 International Publication WO2016 / 170875

However, for example, when carbon black or the like is blended with a hybrid pressure-sensitive adhesive and colored black, there is a problem that light cannot pass through the pressure-sensitive adhesive, which hinders curing and makes it difficult to improve processability. Occurs.

The present invention has been conceived under the above circumstances, and an object of the present invention is to have an antireflection function such as metal wiring and self-luminous emission of a mini / micro LED display device having improved contrast. It is an object of the present invention to provide a pressure-sensitive adhesive composition, a pressure-sensitive adhesive layer, and a pressure-sensitive adhesive sheet, which are suitable for manufacturing a type display device and have excellent step absorption and processability.

As a result of diligent studies to achieve the above object, the present inventors have shown that the pressure-sensitive adhesive composition, the photo-curable pressure-sensitive adhesive layer, and the photo-curable pressure-sensitive adhesive sheet are absorbent in the visible light region, but are high in the ultraviolet region. It has been found that by coloring so as to have transparency, it can be cured by ultraviolet irradiation while exhibiting high light-shielding property against visible light. Further, as the pressure-sensitive adhesive composition, a pressure-sensitive adhesive composition containing a polymer having a benzophenone structure in a side chain, a mixture of monomer components constituting the polymer, or a partial polymer of a mixture of monomer components constituting the polymer. By using this, it is possible to provide a photocurable pressure-sensitive adhesive layer and a photocurable pressure-sensitive adhesive sheet that can achieve both excellent step absorption before photo-curing and excellent processability after photo-curing, in a self-luminous display device. It has been found that the antireflection function of metal wiring, etc., and the contrast are improved, and that excellent step absorption and workability can be achieved at the same time. The present invention has been completed based on these findings.

The first aspect of the present invention contains a colorant and a polymer (A) having a benzophenone structure in a side chain, and the maximum value of the transmittance at a wavelength of 200 to 400 nm is the maximum of the transmittance at a wavelength of 400 to 700 nm. Provided is a pressure-sensitive adhesive composition that is greater than the value.
The second aspect of the present invention is a mixture of a colorant and a monomer component constituting the polymer (A) having a benzophenone structure in the side chain, or a monomer component constituting the polymer (A) having a benzophenone structure in the side chain. Provided is a pressure-sensitive adhesive composition containing a partial polymer of a mixture, wherein the maximum value of the transmittance at a wavelength of 200 to 400 nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm. The pressure-sensitive adhesive composition according to the first aspect and the second aspect of the present invention may further contain the ethylenically unsaturated compound (B).

In the present specification, the pressure-sensitive adhesive compositions of the first and second aspects of the present invention may be collectively referred to as "pressure-sensitive adhesive composition (A)".
Further, in the present specification, the term "polymer (A) having a benzophenone structure in the side chain" or "BP polymer (A)" means "polymer (A) having a benzophenone structure in the side chain" and "polymer (A) having a benzophenone structure in the side chain" unless otherwise specified. It is intended to include "a mixture of monomer components constituting a polymer (A) having a benzophenone structure in a side chain or a partial polymer of a mixture of monomer components constituting a polymer (A) having a benzophenone structure in a side chain".

Further, the third aspect of the present invention is a pressure-sensitive adhesive layer formed by a cured product of the pressure-sensitive adhesive composition (A), wherein the cured product is a cured product in which the benzophenone structure remains. Provide a sex pressure-sensitive adhesive layer. Further, the fourth aspect of the present invention provides a photocurable pressure-sensitive adhesive sheet having the photocurable pressure-sensitive adhesive layer of the third aspect of the present invention.
In the present specification, the photocurable pressure-sensitive adhesive layer on the third aspect of the present invention may be referred to as "photo-curable pressure-sensitive adhesive layer (A)". Further, the photocurable pressure-sensitive adhesive sheet on the fourth side surface of the present invention may be referred to as "photo-curable pressure-sensitive adhesive sheet (A)".

The photocurable pressure-sensitive adhesive layer (A) is a cured product of the pressure-sensitive adhesive composition (A) and is formed of a cured product in which the benzophenone structure of the BP polymer (A) remains. This benzophenone structure can be cured by forming a crosslinked structure by irradiation with ultraviolet rays. The photocurable pressure-sensitive adhesive layer (A) before curing is in a semi-cured state with high fluidity and exhibits excellent step absorption. Therefore, when the photocurable pressure-sensitive adhesive layer (A) before curing is bonded to the display panel in which the light emitting elements (LED chips) are arranged at high density, the fine steps between the light emitting elements (LED chips) are sufficiently formed. It follows and adheres tightly without leaving any bubbles. On the other hand, the photocurable pressure-sensitive adhesive layer (A) after curing exhibits excellent processability. Therefore, when the laminated body containing the photocurable pressure-sensitive adhesive layer (A) after curing is cut, the adhesive is chipped, and when stored, the pressure-sensitive adhesive layer is suppressed from protruding from the end and dripping. As described above, according to the photocurable pressure-sensitive adhesive layer (A) composed of the cured product of the pressure-sensitive adhesive composition (A), excellent step absorption and processability can be suitably compatible.

In the pressure-sensitive adhesive composition (A), the maximum value of the transmittance at a wavelength of 200 to 400 nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm. Further, in the photocurable pressure-sensitive adhesive layer (A), it is preferable that the maximum value of the transmittance at a wavelength of 200 to 400 nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm. That is, the pressure-sensitive adhesive composition (A) and the photocurable pressure-sensitive adhesive layer (A) have high absorption to visible light (wavelength 400 to 700 nm) and excellent light-shielding properties. The structure in which the pressure-sensitive adhesive composition (A) and the photo-curable pressure-sensitive adhesive layer (A) are excellent in light-shielding property against visible light is such that the photo-curable pressure-sensitive adhesive layer is filled without gaps in minute steps between LED chips. A) is preferable in that it prevents reflection due to metal wiring or the like on the display panel, prevents color mixing between the arranged light emitting elements (LED chips), and improves contrast. On the other hand, the pressure-sensitive adhesive composition (A) and the photocurable pressure-sensitive adhesive layer (A) have high transparency to ultraviolet rays (wavelength 200 to 400 nm). In the configuration in which the pressure-sensitive adhesive composition (A) and the photocurable pressure-sensitive adhesive layer (A) have excellent transparency to ultraviolet rays, the curing reaction proceeds by irradiating the photo-curable pressure-sensitive adhesive layer (A) with ultraviolet rays. , It is preferable in that the processability of the photocurable pressure-sensitive adhesive layer (A) is improved. That is, the configuration in which the maximum value of the transmittance of the pressure-sensitive adhesive composition (A) and the photocurable pressure-sensitive adhesive layer (A) at a wavelength of 200 to 400 nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm is visible. It is preferable in that it can achieve both excellent light-shielding property against light and a curing reaction by irradiation with ultraviolet rays.

The colorant is preferably a colorant in which the maximum value of the transmittance at a wavelength of 200 to 400 nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm. In this configuration, the maximum value of the transmittance of the pressure-sensitive adhesive composition (A) and the photocurable pressure-sensitive adhesive layer (A) at a wavelength of 200 to 400 nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm. It is preferable to realize.
In the present specification, "a colorant in which the maximum value of the transmittance at a wavelength of 200 to 400 nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm" may be referred to as "colorant (A)".

The pressure-sensitive adhesive composition (A) preferably further contains a photopolymerization initiator (C) that absorbs ultraviolet rays having a wavelength of 300 nm to 500 nm to generate radicals. This configuration is preferable in that the pressure-sensitive adhesive composition (A) is cured on a cured product in which the benzophenone structure of the BP polymer (A) remains to obtain a photocurable pressure-sensitive adhesive layer (A).

The storage elastic modulus (G'b85) of the photocurable pressure-sensitive adhesive layer (A) before curing at 85 ° C. is preferably less than 65 kPa. This configuration is preferable because the photocurable pressure-sensitive adhesive layer (A) before curing exhibits excellent step absorption.

The storage elastic modulus (G'a10) of the photocurable pressure-sensitive adhesive layer (A) after curing at 10 ° C. and the storage elastic modulus (G'b85) of the photo-curable pressure-sensitive adhesive layer (A) before curing at 85 ° C. It is preferable to satisfy the following relational expression (1).
2.8 <G'a10 / G'b85 (1)
This configuration is preferable in that the photocurable pressure-sensitive adhesive layer (A) before curing exhibits excellent step absorption, and the photo-curable pressure-sensitive adhesive layer (A) after curing exhibits excellent processability.

The storage elastic modulus (G'a10) of the photocurable pressure-sensitive adhesive layer (A) after curing at 10 ° C. is preferably 90 kPa or more. This configuration is preferable in that the photocurable pressure-sensitive adhesive layer (A) after curing exhibits excellent processability.

It is preferable that the curing is performed by irradiation with ultraviolet rays having a wavelength of less than 300 nm and an integrated light amount of 3000 mJ / cm ² . This configuration is preferable in that the photocurable pressure-sensitive adhesive layer (A) is cured by forming a crosslinked structure of the benzophenone structure by irradiation with ultraviolet rays, and exhibits excellent processability.

Further, the fifth aspect of the present invention is a self-luminous display device including a display panel in which a plurality of light emitting elements are arranged on one side of a substrate and the photocurable adhesive sheet (A), and the display thereof. The light emitting element of the panel is sealed with the photocurable pressure-sensitive adhesive layer (A) of the photo-curable pressure-sensitive adhesive sheet (A), and the photo-curable pressure-sensitive adhesive layer (A) is cured. A type display device is provided. In the self-luminous display device according to the fifth aspect of the present invention, the display panel may be an LED panel in which a plurality of LED chips are arranged on one side of a substrate. In such a configuration, in the self-luminous display device on the fifth side surface of the present invention, the photocurable pressure-sensitive adhesive layer (A) in which the minute steps between the light-emitting elements (LED chips) are filled without gaps is formed on the substrate. It is preferable in that it can prevent reflection of metal wiring, prevent RGB color mixing, and improve contrast.

The self-luminous display device according to the fifth aspect of the present invention can be manufactured by a method including the following steps.
A photocurable pressure-sensitive adhesive layer (A) of a photo-curable pressure-sensitive adhesive sheet (A) is laminated on a display panel in which a plurality of light-emitting elements are arranged on one side of a substrate, and the light-emitting element is formed into a photo-curable pressure-sensitive adhesive layer (A). ), And the step of irradiating the photocurable pressure-sensitive adhesive layer (A) with ultraviolet rays to cure it.
Since the photocurable pressure-sensitive adhesive layer (A) before curing has excellent step absorption, it sufficiently follows the minute steps between the light emitting elements and adheres without leaving any bubbles. Then, the photocurable pressure-sensitive adhesive layer (A) is cured by irradiating it with ultraviolet rays, resulting in excellent processability.

In the method for manufacturing a self-luminous display device according to the fifth aspect of the present invention, the ultraviolet rays are preferably ultraviolet rays having a wavelength of less than 300 nm. This configuration is preferable in that the photocurable pressure-sensitive adhesive layer (A) is cured by forming a crosslinked structure of the benzophenone structure by irradiation with ultraviolet rays, and exhibits excellent processability.

The pressure-sensitive adhesive composition, the photo-curable pressure-sensitive adhesive layer, and the photo-curable pressure-sensitive adhesive sheet of the present invention have high light-shielding property against visible light and excellent step absorption. The steps between the plurality of light emitting elements are filled without gaps, the reflection from the metal wiring is prevented, the color mixing between the plurality of light emitting elements is suppressed, and the contrast is improved. In addition, it is cured by irradiation with ultraviolet rays to improve workability, and it is possible to suppress the occurrence of adhesive chipping during cutting, and the adhesive layer squeezing out and sagging from the edges during storage. Therefore, by using the pressure-sensitive adhesive composition, the photo-curable pressure-sensitive adhesive layer, and the photo-curable pressure-sensitive adhesive sheet of the present invention in the manufacture of a self-luminous display device, the antireflection function of metal wiring and the like, and the contrast are improved. The light emitting display device can be efficiently manufactured.

FIG. 1 is a diagram (cross-sectional view) schematically showing an embodiment of the photocurable pressure-sensitive adhesive sheet of the present invention. FIG. 2 is a diagram (cross-sectional view) schematically showing an embodiment of the photocurable pressure-sensitive adhesive sheet of the present invention. FIG. 3 is a diagram (cross-sectional view) schematically showing an embodiment of the photocurable pressure-sensitive adhesive sheet of the present invention. FIG. 4 is a schematic view (cross-sectional view) showing an embodiment of the self-luminous display device (mini / micro LED display device) of the present invention. FIG. 5 is a schematic view (cross-sectional view) showing a process for implementing an embodiment of the method for manufacturing a self-luminous display device (mini / micro LED display device) of the present invention.

The embodiments of the present invention will be described with reference to the drawings as necessary, but the present invention is not limited thereto and is merely an example.

As used herein, the term "acrylic polymer" refers to a polymer derived from a monomer component containing an acrylic monomer in an amount of more than 50% by weight (preferably more than 70% by weight, for example, more than 90% by weight). The acrylic monomer refers to a monomer derived from a monomer having at least one (meth) acryloyl group in one molecule. Further, in this specification, "(meth) acryloyl" means a comprehensively referring to acryloyl and methacryloyl. Similarly, "(meth) acrylate" means acrylate and methacrylate, and "(meth) acrylic" means acrylic and methacrylic, respectively.

As used herein, the term "ethylenically unsaturated compound" refers to a compound having at least one ethylenically unsaturated group in the molecule. Examples of the ethylenically unsaturated group include a (meth) acryloyl group, a vinyl group, an allyl group and the like. Hereinafter, a compound having one ethylenically unsaturated group may be referred to as a “monofunctional monomer”, and a compound having two or more ethylenically unsaturated groups may be referred to as a “polyfunctional monomer”. Further, among the polyfunctional monomers, a compound having X ethylenically unsaturated groups may be described as "X-functional monomer".

In this specification, the fact that the pressure-sensitive adhesive composition contains an ethylenically unsaturated compound means that the above-mentioned ethylenically unsaturated compound is contained in the form of a partial polymer, unless otherwise specified. Such a partial polymer usually contains the ethylenically unsaturated compound (unreacted monomer) in which the ethylenically unsaturated group is unreacted and the ethylenically unsaturated compound in which the ethylenically unsaturated group is polymerized. It is a mixture containing.

In the present specification, the entire monomer component constituting the pressure-sensitive adhesive composition refers to the monomer component constituting the polymer contained in the pressure-sensitive adhesive composition and the monomer contained in the pressure-sensitive adhesive composition in the form of an unreacted monomer. The total amount with the ingredients. The composition of the monomer component constituting the pressure-sensitive adhesive composition is usually substantially the same as the composition of the monomer component of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition and the composition of the monomer component constituting the photocured product.

In this specification, "active energy ray" is a concept including light such as ultraviolet rays, visible rays, and infrared rays, and radiation such as α rays, β rays, γ rays, electron rays, neutron rays, and X-rays. be.

[Adhesive composition (A)]
The pressure-sensitive adhesive composition of the first aspect of the present invention contains a colorant and a polymer (A) having a benzophenone structure in a side chain, and has a maximum transmittance of 200 to 400 nm at a wavelength of 400 to 700 nm. Greater than the maximum transmittance.
Further, the pressure-sensitive adhesive composition of the second aspect of the present invention comprises a mixture of a colorant and a monomer component constituting the polymer (A) having a benzophenone structure in the side chain, or the polymer (A) having a benzophenone structure in the side chain. It contains a partial polymer of a mixture of the constituent monomer components, and the maximum value of the transmittance at a wavelength of 200 to 400 nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm.
The pressure-sensitive adhesive composition (the pressure-sensitive adhesive composition (A)) of the first and second aspects of the present invention may further contain an ethylenically unsaturated compound (B).
In addition to the above, the pressure-sensitive adhesive composition (A) may contain a photopolymerization initiator (C) that absorbs ultraviolet rays having a wavelength of 300 nm to 500 nm and generates radicals, which will be described later, and other additives.
In the present specification, the above-mentioned "mixture of monomer components" includes a case of being composed of a single monomer component and a case of being composed of two or more kinds of monomer components. Further, the above-mentioned "partial polymer of a mixture of monomer components" means a composition in which one or more of the constituent monomer components of the above-mentioned "mixture of monomer components" are partially polymerized. do.

The pressure-sensitive adhesive composition (A) may have any form, for example, a solvent type, an emulsion type, a heat melt type (hot melt type), a solventless type (active energy ray curable type, for example, a monomer). A mixture, a monomer mixture and a partial polymer thereof, etc.) and the like can be mentioned. The pressure-sensitive adhesive composition (A) of the present invention is preferably an active energy ray-curable type from the viewpoint of obtaining a pressure-sensitive adhesive layer having excellent appearance. In the present specification, the pressure-sensitive adhesive composition means a composition used for forming a pressure-sensitive adhesive layer, and includes the meaning of a composition used for forming a pressure-sensitive adhesive.

The pressure-sensitive adhesive composition (A) is not particularly limited, but for example, a composition containing the BP polymer (A) as an essential component; a mixture of monomer components constituting the BP polymer (A) or a partial polymer thereof is an essential component. And the like. Although not particularly limited, the former includes, for example, a so-called solvent-type pressure-sensitive adhesive composition, an aqueous dispersion-type pressure-sensitive adhesive composition (emulsion-type pressure-sensitive adhesive composition), and the like, and the latter includes, for example, so-called active energy ray curing. Examples thereof include a mold pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition (A) may be a solvent type as described above. The solvent is not particularly limited as long as it is an organic compound used as a solvent, and for example, a hydrocarbon solvent such as cyclohexane, hexane, and heptane; an aromatic solvent such as toluene and xylene; ethyl acetate, methyl acetate, and the like. Ester-based solvents; ketone-based solvents such as acetone and methyl ethyl ketone; alcohol-based solvents such as methanol, ethanol, butanol and isopropyl alcohol may be mentioned. The solvent may be a mixed solvent containing two or more kinds of solvents.

The pressure-sensitive adhesive composition (A) is an acrylic pressure-sensitive adhesive composition in which more than 50% by weight (preferably more than 70% by weight, for example, more than 90% by weight) of the total monomer components constituting the pressure-sensitive adhesive composition is an acrylic-based monomer. It can be a thing.

In the pressure-sensitive adhesive composition (A), the maximum value of the transmittance at a wavelength of 200 to 400 nm (preferably a wavelength of 330 to 400 nm) is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm.

The pressure-sensitive adhesive composition (A) has low transparency to visible light (wavelength 400 to 700 nm), that is, has high light-shielding property. The photocurable pressure-sensitive adhesive layer (A) formed from the cured product of the pressure-sensitive adhesive composition (A) having excellent light-shielding property against visible light is the metal wiring layer of the self-luminous display device (mini / micro LED display device). By sealing the minute steps between the light emitting elements (LED chips) without gaps, reflection due to metal wiring or the like is prevented, color mixing of the light emitting elements (LED chips) is prevented, and image contrast is improved.

On the other hand, the pressure-sensitive adhesive composition (A) has a higher transmittance in the ultraviolet region (wavelength 200 to 400 nm, preferably wavelength 330 to 400 nm) than visible light. Therefore, in the photocurable pressure-sensitive adhesive layer (A) formed from the cured product of the pressure-sensitive adhesive composition (A), the benzophenone structure can be cured by forming a crosslinked structure by irradiating with ultraviolet rays. The photocurable pressure-sensitive adhesive layer (A) cured by irradiation with ultraviolet rays has improved workability, and suppresses adhesive chipping during cutting and protrusion and sagging of the pressure-sensitive adhesive layer from the edges during storage.

In the present specification, the "maximum value of the transmittance at a wavelength of 200 to 400 nm" means the highest transmittance in the range of the wavelength range of 200 to 400 nm. For example, when there is one maximum value of transmittance in the region of wavelength 200 to 400 nm, the maximum value is the maximum value of transmittance. When there is no maximum value of the transmittance in the region of the wavelength of 200 to 400 nm, the higher of the transmittance of the wavelength of 200 nm or 400 nm is the maximum value. The same applies to the "maximum value of the transmittance at a wavelength of 330 to 400 nm" and the "maximum value of the transmittance at a wavelength of 400 to 700 nm".

The maximum value of the transmittance of the pressure-sensitive adhesive composition (A) at a wavelength of 400 to 700 nm (visible light region) is, for example, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30%. Below, it may be 20% or less, 10% or less, or 5% or less.

Further, in a preferred embodiment of the present invention, the pressure-sensitive adhesive composition (A) has an average transmittance of a wavelength of 200 to 400 nm (preferably a wavelength of 330 to 400 nm) larger than an average transmittance of a wavelength of 400 to 700 nm. The average transmittance of the pressure-sensitive adhesive composition (A) at a wavelength of 400 to 700 nm (visible light region) is, for example, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, It may be 20% or less, 10% or less, or 5% or less.

[Colorant]
The pressure-sensitive adhesive composition (A) contains a colorant. The colorant is not particularly limited, but the maximum value of the transmittance at a wavelength of 200 to 400 nm (preferably a wavelength of 330 to 400 nm) is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm (colorant (A). )).

The structure in which the pressure-sensitive adhesive composition (A) has a maximum transmittance at a wavelength of 200 to 400 nm (preferably a wavelength of 330 to 400 nm) is larger than a maximum value of a transmittance at a wavelength of 400 to 700 nm is not particularly limited. The pressure-sensitive adhesive composition (A) can be realized by containing the colorant (A).

When the pressure-sensitive adhesive composition (A) contains the colorant (A), the transmittance to visible light (wavelength 400 to 700 nm) is lowered, that is, the light-shielding property is improved, while the ultraviolet region (wavelength) is higher than that of visible light. The transmittance is increased at 200 to 400 nm, preferably at a wavelength of 330 to 400 nm).

The maximum value of the transmittance of the colorant (A) at a wavelength of 400 to 700 nm (visible light region) is, for example, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less. , 20% or less, 10% or less, or 5% or less.

Further, in a preferred embodiment of the present invention, the colorant (A) has a larger average transmittance at a wavelength of 200 to 400 nm (preferably a wavelength of 330 to 400 nm) than an average transmittance at a wavelength of 400 to 700 nm. The average transmittance of the colorant (A) at a wavelength of 400 to 700 nm (visible light region) is, for example, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20. It may be% or less, 10% or less, or 5% or less.

The transmittance of the colorant is determined by using an appropriate solvent such as tetrahydrofuran (THF) or a dispersion medium (an organic solvent having a small absorption in the wavelength range of 200 to 700 nm) so that the transmittance at a wavelength of 400 nm is about 50 to 60%. It can be measured using a diluted solution or dispersion.

The colorant may be a dye or a pigment as long as it can be dissolved or dispersed in the pressure-sensitive adhesive composition (A). Dyes are preferable because low haze can be achieved even with a small amount of addition, and unlike pigments, they do not have sedimentation properties and can be easily distributed uniformly. In addition, pigments are also preferable because they have high color expression even when added in a small amount. When a pigment is used as a colorant, it preferably has low or no conductivity. When a dye is used, it is preferably used in combination with an antioxidant or the like.

Examples of the ultraviolet-transparent black pigment include "9500BLACK", "9256BLACK", "9170BLACK", "UVBK-0001" manufactured by Tokushiki, and "UB-1" manufactured by Mitsubishi Materials Electronics Co., Ltd. Examples of the ultraviolet-transparent black dye include "SOC-L-0123" manufactured by Orient Chemical Industries.

The content of the colorant in the pressure-sensitive adhesive composition (A) is, for example, about 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the pressure-sensitive adhesive composition (A). Yes, it may be appropriately set according to the type of the colorant, the color tone of the photocurable pressure-sensitive adhesive layer (A), the light transmittance, and the like. The colorant may be added as a solution or dispersion dissolved or dispersed in an appropriate solvent.

[Polymer (A) having a benzophenone structure in the side chain]
As the base polymer constituting the pressure-sensitive adhesive composition (A) of the present invention, a polymer (A) having a benzophenone structure in a side chain (BP polymer (A)) is included. That is, the pressure-sensitive adhesive composition (A) of the present invention is a pressure-sensitive adhesive composition containing the BP polymer (A) as a base polymer. The BP polymer (A) can be used alone or in combination of two or more.

The monomer component that can constitute the BP polymer (A) includes a compound having an ethylenically unsaturated group and a benzophenone structure in the molecule (hereinafter, may be referred to as “ethylenically unsaturated BP”), and further. , Ethylene unsaturated compounds that do not fall under ethylenically unsaturated BP (hereinafter, also referred to as “other ethylenically unsaturated compounds”) may be included.

A preferable example of the BP polymer (A) is an acrylic polymer having a benzophenone structure in the side chain. The BP polymer (A) is preferably a polymer that does not substantially contain an ethylenically unsaturated group.

As used herein, the term "benzophenone structure" refers to a diallyl ketone structure represented by the general formula: Ar ^1- (C = O) -Ar ^2- ; or -Ar ^3- (C = O) -Ar ^2- ; To say. Here, Ar ¹ in the above general formula is selected from phenyl groups which may have a substituent. Ar ² and Ar ³ in the above general formula are independently selected from phenylene groups which may have a substituent. Ar ² and Ar ³ may be the same or different. The benzophenone structure can be excited by irradiation with ultraviolet light, and in the excited state, hydrogen radicals can be extracted from other molecules or other parts of the molecules.

The photocurable pressure-sensitive adhesive layer (A) formed from the cured product of the pressure-sensitive adhesive composition (A) containing the BP polymer (A) may contain a benzophenone structure. The benzophenone structure can cure the photocurable pressure-sensitive adhesive layer (A) by forming a crosslinked structure by utilizing the extraction reaction of hydrogen radicals by exciting with ultraviolet irradiation.

As the BP polymer (A), Ar ¹ in the general formula: Ar ¹ − (C = O) − Ar ² −; is a phenyl group which may have a substituent, and Ar ² is a substituent. A polymer having a benzophenone structure, which is a phenylene group which may have a phenylene group, in the side chain is preferable. When at least one of Ar ¹ and Ar ² has one or more substituents, the substituents are independently alkoxy groups (for example, alkoxy groups having 1 to 3 carbon atoms, preferably methoxy groups). It can be selected from the group consisting of halogen atoms (eg, F, Cl, Br, etc., preferably Cl or Br), hydroxyl groups, amino groups and carboxyl groups.

The BP polymer (A) may have a benzophenone structure as described above having a side chain directly bonded to the main chain, for example, via one or more of an ester bond, an oxyalkylene structure, and the like. It may have a side chain bonded to the main chain. A preferred example of the BP polymer (A) is a polymer containing a repeating unit derived from an ethylenically unsaturated BP. The repeating unit may be a polymerization residue reacted with an ethylenically unsaturated group of the corresponding ethylenically unsaturated BP.

Examples of the ethylenically unsaturated BP include 4-acryloyloxybenzophenone, 4-acryloyloxy-4'-methoxybenzophenone, 4-acryloyloxyethoxy-4'-methoxybenzophenone, and 4-acryloyloxy-4'-bromobenzophenone. Acryloyloxybenzophenone, which may have a substituent, such as 2-hydroxy-4-acryloyloxybenzophenone; 4-[(2-acryloyloxy) ethoxy] benzophenone, 4-[(2-acryloyloxy) ethoxy]. Acryloyloxyalkoxybenzophenone which may have a substituent such as -4'-bromobenzophenone; 4-methacryloyloxybenzophenone, 4-methacryloyloxy-4'-methoxybenzophenone, 4-methacryloyloxy-4'-bromobenzophenone. , 4-Methacloyloxyethoxy-4'-bromobenzophenone, 2-hydroxy-4-methacryloyloxybenzophenone, and the like, which may have substituents; 4-[(2-methacryloyloxy) ethoxy] benzophenone. , 4-[(2-methacryloyloxy) ethoxy] -4'-methoxybenzophenone and the like, which may have a substituent, methacryloyloxyalkoxybenzophenone; 4-vinylbenzophenone, 4'-bromo-3-vinylbenzophenone, Examples thereof include, but are not limited to, vinylbenzophenone which may have a substituent, such as 2-hydroxy4-methoxy-4'-vinylbenzophenone. Ethylene unsaturated BP can be used alone or in combination of two or more for the preparation of the BP polymer (A). As the ethylenically unsaturated BP, a commercially available product can be used, and the ethylenically unsaturated BP can be synthesized by a known method. From the viewpoint of reactivity and the like, an ethylenically unsaturated BP having a (meth) acryloyl group, that is, an ethylenically unsaturated BP which is an acrylic monomer can be preferably adopted.

The BP polymer (A) has a repeating unit derived from an ethylenically unsaturated BP and a repeating unit derived from an ethylenically unsaturated compound (another ethylenically unsaturated compound) that does not correspond to the ethylenically unsaturated BP. It may be a copolymer. Such a BP polymer (A) can be a copolymer of a monomer component containing the ethylenically unsaturated BP and the other ethylenically unsaturated compound. Further, the BP polymer may also be a copolymer obtained by copolymerizing a partial polymer (prepolymer) of a monomer mixture composed of only the other ethylenically unsaturated compound and the ethylenically unsaturated BP. As the other ethylenically unsaturated compound, one or more acrylic monomers may be preferably adopted. As a preferable example of the BP polymer (A), an acrylic BP polymer in which more than 50% by weight (preferably more than 70% by weight, for example, more than 90% by weight) of the monomer component constituting the BP polymer (A) is an acrylic monomer. Can be mentioned.

The monomer component constituting the BP polymer (A) may contain one or more selected from (meth) acrylic acid alkyl esters having an alkyl group at the ester terminal as the other ethylenically unsaturated compound. Hereinafter, a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having an number of carbon atoms of X or more and Y or less at the ester terminal may be referred to as "(meth) acrylic acid C _XY alkyl ester". .. The monomer component constituting the BP polymer (A) preferably contains at least (meth) acrylic acid C _1-20 alkyl ester as the other monomer, and preferably contains (meth) acrylic acid C _4-20 alkyl ester. Is more preferable, and it is even more preferable to contain (meth) acrylic acid C _4-18 alkyl ester (for example, acrylic acid C _4-9 alkyl ester).

Non-limiting specific examples of (meth) acrylic acid C _1-20 alkyl ester include methyl (meth) acrylic acid, ethyl (meth) acrylic acid, propyl (meth) acrylic acid, isopropyl (meth) acrylic acid, (. N-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, (meth) Hexyl acrylate, (meth) heptyl acrylate, (meth) octyl acrylate, (meth) 2-ethylhexyl acrylate, (meth) isooctyl acrylate, (meth) nonyl acrylate, (meth) isononyl acrylate, (meth) ) Decyl acrylate, (meth) isodecyl acrylate, (meth) undecyl acrylate, (meth) dodecyl acrylate, (meth) tridecyl acrylate, (meth) tetradecyl acrylate, (meth) pentadecyl acrylate, (meth) Examples thereof include hexadecyl acrylate, heptadecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, nonadecil (meth) acrylate, and eicocil (meth) acrylate. Particularly preferable (meth) acrylic acid alkyl esters include n-butyl acrylate (BA), 2-ethylhexyl acrylate (2EHA), and isononyl acrylate. Other specific examples of the (meth) acrylic acid alkyl ester that can be preferably used include n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA), isostearyl acrylate (iSTA) and the like. The (meth) acrylic acid alkyl ester may be used alone or in combination of two or more. The monomer component constituting the BP polymer (A) may contain one or more selected from the copolymerizable monomers described later as the other ethylenically unsaturated compounds.

The pressure-sensitive adhesive composition (A) is a photocurable acrylic pressure-sensitive adhesive composition in which more than 50% by weight (preferably more than 70% by weight, for example, more than 90% by weight) of the total constituent monomer components are acrylic monomers. possible. The photocurable acrylic pressure-sensitive adhesive composition forms an acrylic photocurable product by photocuring.

The weight average molecular weight (Mw) of the BP polymer (A) is not particularly limited and may be, for example, about 0.5 × 10 ⁴ to 500 × 10 ⁴ . From the viewpoint of the cohesiveness of the photocurable pressure-sensitive adhesive layer (A) and the handleability of the photo-curable pressure-sensitive adhesive sheet (A), the Mw of the BP polymer (A) is usually 1 × 10 ⁴ or more. Is appropriate, and is preferably 5 × 10 ⁴ or more, 10 × 10 ⁴ or more, 15 × 10 ⁴ or more, or 20 × 10 ⁴ or more. Further, from the viewpoint of the step absorption of the photocurable pressure-sensitive adhesive layer (A), it is usually appropriate that the Mw of the BP polymer (A) is 200 × 10 ⁴ or less, and 150 × 10 ⁴ or less. It is preferable that it is 100 × 10 ⁴ or less, 70 × 10 ⁴ or less, or 50 × 10 ⁴ or less.
The weight average molecular weight (Mw) of the polymer means a value in terms of standard polystyrene obtained by gel permeation chromatography (GPC). As the GPC apparatus, for example, a model name “HLC-8320GPC” (column: TSKgelGMH-H (S), manufactured by Tosoh Corporation) can be used.

The glass transition temperature (Tg) of the BP polymer (A) is not particularly limited. The Tg of the BP polymer (A) may be, for example, −80 ° C. or higher and 150 ° C. or lower, −80 ° C. or higher and 50 ° C. or lower, or −80 ° C. or higher and 10 ° C. or lower. From the viewpoint of the step absorption of the photocurable pressure-sensitive adhesive layer (A), the Tg of the BP polymer (A) is preferably less than 0 ° C, preferably −10 ° C or lower, and preferably −20 ° C. It may be -30 ° C or lower, -40 ° C or lower, or -50 ° C or lower. Further, from the viewpoint of the cohesiveness of the photocurable pressure-sensitive adhesive layer (A) and the improvement of processability after photocuring, it is usually advantageous that the Tg of the BP polymer (A) is −75 ° C. or higher. It may be 70 ° C. or higher. In some embodiments, the Tg of the BP polymer (A) may be −55 ° C. or higher, or −45 ° C. or higher. The Tg of the BP polymer (A) can be adjusted by the type and amount of the monomer components constituting the BP polymer.

Here, the glass transition temperature (Tg) of the polymer means the glass transition temperature obtained by the Fox formula based on the composition of the monomer components constituting the polymer. As shown below, the Fox formula is a relational formula between the Tg of the copolymer and the glass transition temperature Tgi of the homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer.
1 / Tg = Σ (Wi / Tgi)
In the above Fox formula, Tg is the glass transition temperature (unit: K) of the copolymer, Wi is the weight fraction of the monomer i in the copolymer (copolymerization ratio based on the weight), and Tgi is the monomer i. Represents the glass transition temperature (unit: K) of the homopolymer.

As the glass transition temperature of the homopolymer used for calculating Tg, the value described in the publicly known material shall be used. For example, for the monomers listed below, the following values are used as the glass transition temperature of the homopolymer of the monomer.
2-Ethylhexyl acrylate: -70 ° C
n-Butyl acrylate: -55 ° C
Isostearyl acrylate: -18 ° C
Methyl methacrylate: 105 ° C
Methyl acrylate: 8 ° C
Cyclohexyl acrylate: 15 ° C
N-vinyl-2-pyrrolidone: 54 ° C
2-Hydroxyethyl acrylate: -15 ° C
4-Hydroxybutyl acrylate: -40 ° C
Isobornyl acrylate: 94 ° C
Acrylic acid: 106 ° C
Methacrylic acid: 228 ° C

For the glass transition temperature of homopolymers of monomers other than those exemplified above, the numerical values described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) shall be used. When multiple types of values are described in this document, the highest value is adopted. For the monomers for which the glass transition temperature of the homopolymer is not described in the Polymer Handbook, the values obtained by the measuring method described in JP-A-2007-51271 shall be used. For a polymer for which a nominal value of glass transition temperature is provided by a manufacturer or the like, the nominal value may be adopted.

The BP polymer (A) preferably contains a benzophenone structure in an amount of about 0.5 mg or more in terms of 4-benzoylphenyl acrylate, per 1 g of the polymer. Hereinafter, the value obtained by converting the number of benzophenone structures contained in 1 g of the BP polymer into the amount converted to 4-benzoylphenyl acrylate may be referred to as the BP equivalent (unit: mg / g) of the BP polymer. For example, if it contains 40 μmol of benzophenone structure per gram, the BP equivalent of the polymer is calculated to be 10 mg / g.

From the viewpoint of obtaining a higher photocuring effect (for example, the effect of enhancing processability by photocuring), in some embodiments, the BP equivalent of the BP polymer (A) is usually 0.1 mg / g or more. Appropriate, 0.5 mg / g or more, 1 mg / g or more, 5 mg / g or more, 8 mg / g or more, 10 mg / g or more, 15 mg / g or more, 20 mg / g It may be g or more. Further, in some embodiments, it is appropriate that the BP equivalent of the BP polymer (A) is usually 100 mg / g or less from the viewpoint of enhancing the impact resistance and peel strength of the joint portion due to the photocured product. It may be 80 mg / g or less, 60 mg / g or less, 40 mg / g or less, 25 mg / g or less, or 15 mg / g or less. The BP equivalent of the BP polymer (A) can be adjusted by the composition of the monomer components constituting the BP polymer (A).

In addition, from the viewpoint of reducing the peeling force by photocuring and performing rework or repair, the BP equivalent is preferably 50 mg / g or more, and may be 100 mg / g or more.

The weight ratio of the BP polymer (A) to the entire pressure-sensitive adhesive composition (A), that is, the weight fraction of the BP polymer in the pressure-sensitive adhesive composition (A) is not particularly limited, and the photocurable pressure-sensitive adhesive layer (A). ) Can be set so as to have a good balance between the step absorption property and the processability of the photo-cured product. In some embodiments, the weight fraction of the BP polymer (A) may be, for example, 1% by weight or more, usually 5% by weight or more, 10% by weight or more, and 15% by weight. It may be 50% by weight or more, 25% by weight or more, 35% by weight or more, 45% by weight or more, or 55% by weight or more. As the weight fraction of the BP polymer (A) increases, G'a10 / G'b85, which will be described later, tends to increase.
It can also be carried out in an embodiment in which the weight fraction of the BP polymer (A) in the pressure-sensitive adhesive composition (A) is substantially 100% by weight (for example, 99.5% by weight or more). Further, from the viewpoint of ease of adhesive performance, in some embodiments, the weight fraction of the BP polymer (A) in the pressure-sensitive adhesive composition (A) may be, for example, less than 99% by weight, less than 95% by weight. It may be less than 85% by weight, less than 70% by weight, less than 50% by weight, or less than 40% by weight.

It is preferable that 1 g of the pressure-sensitive adhesive composition (A) contains a benzophenone structure of, for example, about 0.1 mg or more in terms of 4-benzoylphenyl acrylate. Hereinafter, the weight of the benzophenone structure in terms of 4-benzoylphenyl acrylate contained in 1 g of the pressure-sensitive adhesive composition (A) may be referred to as the BP equivalent (unit: mg / g) of the pressure-sensitive adhesive composition. From the viewpoint of obtaining a higher photocuring effect (for example, the effect of enhancing processability by photocuring), in some embodiments, the BP equivalent of the pressure-sensitive adhesive composition is usually preferably 0.3 mg / g or more. It may be 0.5 mg / g or more, 1 mg / g or more, 5 mg / g or more, 10 mg / g or more, or 20 mg / g or more. Further, in some embodiments, the BP equivalent of the pressure-sensitive adhesive composition is usually preferably 100 mg / g or less from the viewpoint of impact resistance of the joint portion by the photo-cured product and suppression of strain in the photo-cured product. It may be 80 mg / g or less, 60 mg / g or less, 40 mg / g or less, 25 mg / g or less, or 15 mg / g or less.

[Ethylene unsaturated compound (B)]
The pressure-sensitive adhesive composition (A) may further contain an ethylenically unsaturated compound (B) in addition to the BP polymer (A). When the pressure-sensitive adhesive composition (A) is a solvent-free type (active energy ray-curable type) pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition (A) contains an ethylenically unsaturated compound (B). Is preferable. On the other hand, when the pressure-sensitive adhesive composition (A) is a solvent-type or emulsion-type pressure-sensitive adhesive composition, it does not have to contain the ethylenically unsaturated compound (B).

When the pressure-sensitive adhesive composition (A) contains a partial polymer of a mixture of monomer components constituting the BP polymer (A) or a mixture of the monomer components constituting the BP polymer (A), the monomer component thereof is used. Since it may contain the other ethylenically unsaturated compound described above, it does not necessarily have to contain the ethylenically unsaturated compound (B). When the pressure-sensitive adhesive composition (A) containing the mixture of the monomer components or a partial polymer thereof contains the ethylenically unsaturated compound (B), the ethylenically unsaturated compound (B) is the above-mentioned other ethylenically unsaturated compound. It may be the same as or different from the saturated compound.

Examples of the compound that can be used as the ethylenically unsaturated compound (B) include the above-mentioned (meth) acrylic acid alkyl ester and the above-mentioned ethylenically unsaturated BP. Of these, at least (meth) acrylic acid alkyl esters (eg, (meth) acrylic acid C _1-20 alkyl esters, more preferably (meth) acrylic acid C _4-18 alkyl esters, and even more preferably acrylic acid C _4-9 . Alkyl ester) is preferably used. Particularly preferred (meth) acrylic acid alkyl esters include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA). Other specific examples of the (meth) acrylic acid alkyl ester that may be preferably used include isononyl acrylate, n-butyl methacrylate (BMA), 2-ethylhexyl methacrylate (2EHMA), isostearyl acrylate (iSTA) and the like. Can be mentioned. The (meth) acrylic acid alkyl ester may be used alone or in combination of two or more. In some embodiments, the ethylenically unsaturated compound (B) preferably comprises either or both of n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA), with at least BA. It is more preferable to include it.

The ethylenically unsaturated compound (B) may contain acrylic acid C _4-9 alkyl ester in a proportion of 40% by weight or more. The ratio of acrylic acid C _4-9 alkyl ester to the monomer component may be, for example, 50% by weight or more, 60% by weight or more, or 65% by weight or more. Further, from the viewpoint of enhancing the cohesiveness of the photocurable pressure-sensitive adhesive layer (A), the ratio of acrylic acid C _4-9 alkyl ester to the ethylenically unsaturated compound (B) is usually 99.5% by weight or less. It may be 95% by weight or less, 85% by weight or less, 70% by weight or less, or 60% by weight or less.

As another example of the compound that can be used as the ethylenically unsaturated compound (B), there is an ethylenically unsaturated compound (copolymerizable monomer) copolymerizable with the (meth) acrylic acid alkyl ester. As the copolymerizable monomer, a monomer having a polar group (for example, a carboxy group, a hydroxyl group, a nitrogen atom-containing ring, etc.) can be preferably used. A monomer having a polar group can be useful, for example, to introduce a cross-linking point into a polymer containing a repeating unit derived from the monomer, or to enhance the cohesive force of the photocurable pressure-sensitive adhesive layer (A). The copolymerizable monomer may be used alone or in combination of two or more.

Non-limiting specific examples of the copolymerizable monomer include the following.
Monomer containing carboxy group: For example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid and the like.
Acid anhydride group-containing monomer: For example, maleic anhydride, itaconic anhydride.
Hydroxyl-containing monomers: For example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, (meth) acrylic. 4-Hydroxybutyl acid, 6-hydroxyhexyl (meth) acrylic acid, 8-hydroxyoctyl (meth) acrylic acid, 10-hydroxydecyl (meth) acrylic acid, 12-hydroxylauryl (meth) acrylic acid, (4-hydroxy) Methylcyclohexyl) Methyl (meth) acrylate and the like (meth) hydroxyalkyl acrylate and the like.
Monomer containing a sulfonic acid group or a phosphate group: for example, styrene sulfonic acid, allyl sulfonic acid, sodium vinyl sulfonic acid, 2- (meth) acrylamide-2-methyl propane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfo. Propyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid, 2-hydroxyethyl acryloyl phosphate, etc.
Epoxide group-containing monomer: For example, epoxy group-containing acrylate such as (meth) glycidyl acrylate and (meth) -2-ethyl glycidyl ether, allyl glycidyl ether, glycidyl ether (meth) acrylate and the like.
Cyano group-containing monomer: For example, acrylonitrile, methacrylonitrile, etc.
Isocyanate group-containing monomer: for example, 2- (meth) acryloyloxyethyl isocyanate, (meth) acryloyl isocyanate, m-isopropenyl-α, α-dimethylbenzyl isocyanate and the like.
Amide group-containing monomers: For example, (meth) acrylamide; N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N-diisopropyl (meth). N, N-dialkyl (meth) acrylamides such as acrylamide, N, N-di (n-butyl) (meth) acrylamide, N, N-di (t-butyl) (meth) acrylamide; N-ethyl (meth) acrylamide. , N-alkyl (meth) acrylamide such as N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, Nn-butyl (meth) acrylamide; N-vinylcarboxylic acid amides such as N-vinylacetamide; Monomers having a hydroxyl group and an amide group, such as N- (2-hydroxyethyl) (meth) acrylamide, N- (2-hydroxypropyl) (meth) acrylamide, N- (1-hydroxypropyl) (meth) acrylamide, N- (3-Hydroxypropyl) (meth) acrylamide, N- (2-hydroxybutyl) (meth) acrylamide, N- (3-hydroxybutyl) (meth) acrylamide, N- (4-hydroxybutyl) (meth) N-hydroxyalkyl (meth) acrylamide such as acrylamide; monomers having an alkoxy group and an amide group, for example, N-methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide. N-alkoxyalkyl (meth) acrylamide, etc .; In addition, N, N-dimethylaminopropyl (meth) acrylamide, N- (meth) acryloylmorpholine, etc.
Amino group-containing monomer: For example, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate. Monomers having an epoxy group: for example, glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, allyl glycidyl ether.
Monomers having a nitrogen atom-containing ring: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N- Vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N- (meth) acryloyl-2-pyrrolidone, N- (meth) acryloyl piperidine, N- (meth) acryloylpyrrolidin, N-vinylmorpholin, N-vinyl-3. -Morholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxadin-2-one, N-vinyl-3,5-morpholindione, N-vinylpyrazole, N-vinylisoxazole, N-vinyl Thiasol, N-vinylisothiazole, N-vinylpyridazine and the like (eg, lactams such as N-vinyl-2-caprolactam).
Monomers having a succinimide skeleton: for example, N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyhexamethylene succinimide and the like.
Maleimides: For example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide and the like.
Itaconimides: For example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-lauryl. Itaconimide, etc.
Aminoalkyl (meth) acrylates: For example, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, t (meth) acrylate. -Butyl aminoethyl.
Alkoxy group-containing monomers: for example, 2-methoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, (meth) acrylic acid. (Meta) Alkoxyalkyl (alkoxyalkyl (meth) acrylates) such as butoxyethyl, ethoxypropyl (meth) acrylate; (meth) methoxyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, (meth) (Meth) Alkoxyalkylene glycol acrylate (for example, alkoxypolyalkylene glycol (meth) acrylate) such as methoxypolykoxy glycol acrylate.
Alkoxysilyl group-containing monomers: for example 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane, 3- (meth) acryloxy Alkoxysilyl group-containing (meth) acrylates such as propylmethyldiethoxysilane, alkoxysilyl group-containing vinyl compounds such as vinyltrimethoxysilane and vinyltriethoxysilane, and the like.
Vinyl esters: For example, vinyl acetate, vinyl propionate, etc.
Vinyl ethers: For example, vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether.
Aromatic vinyl compounds: For example, styrene, α-methylstyrene, vinyltoluene and the like.
Olefins: For example, ethylene, butadiene, isoprene, isobutylene and the like.
(Meta) acrylic acid ester having an alicyclic hydrocarbon group: For example, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, adamantyl (meth) acrylate and the like. Alicyclic hydrocarbon group-containing (meth) acrylate.
(Meta) acrylic acid ester having an aromatic hydrocarbon group: An aromatic hydrocarbon group-containing (meth) acrylate such as, for example, phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, and benzyl (meth) acrylate.
In addition, heterocyclic-containing (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate, halogen atom-containing (meth) acrylates such as vinyl chloride and fluorine atom-containing (meth) acrylates, and silicon atom-containing silicone (meth) acrylates. (Meta) acrylate, (meth) acrylic acid ester obtained from terpene compound derivative alcohol, etc.

When such a copolymerizable monomer is used, the amount used is not particularly limited, but it is usually appropriate to use 0.01% by weight or more of the total amount of the monomer components constituting the pressure-sensitive adhesive composition (A). be. From the viewpoint of better exerting the effect of using the copolymerizable monomer, the amount of the copolymerizable monomer used (that is, the weight fraction of the copolymerizable monomer in the whole monomer component) is 0.1% by weight of the whole monomer component. It may be more than 0.5% by weight, and it may be 0.5% by weight or more. Further, from the viewpoint of facilitating the balance of the adhesive properties, the amount of the copolymerizable monomer used is usually preferably 50% by weight or less of the total monomer component, and preferably 40% by weight or less.

The copolymerizable monomer may include a monomer having a nitrogen atom. By using a monomer having a nitrogen atom, the cohesive force of the photocurable pressure-sensitive adhesive layer (A) can be enhanced, and the peel strength after photocuring can be preferably improved. A preferred example of a monomer having a nitrogen atom is a monomer having a nitrogen atom-containing ring. As the monomer having a nitrogen atom-containing ring, those exemplified above can be used, and for example, the general formula (1):

The N-vinyl cyclic amide represented by is used. Here, in the general formula (1), R ¹ is a divalent organic group, specifically − (CH ₂ ) _n −. n is an integer of 2 to 7 (preferably 2, 3 or 4). Among them, N-vinyl-2-pyrrolidone can be preferably adopted. Another preferred example of a monomer having a nitrogen atom is (meth) acrylamide.

When a monomer having a nitrogen atom (preferably a monomer having a nitrogen atom-containing ring such as N-vinyl cyclic amide) is used, the amount used is not particularly limited, and is, for example, 1% by weight or more of the total monomer component. It may be 2% by weight or more, 3% by weight or more, and further 5% by weight or more or 7% by weight or more. In one aspect, the amount of the nitrogen atom-containing monomer used may be 10% by weight or more, 15% by weight or more, or 20% by weight or more of the total monomer component. Further, it is appropriate that the amount of the nitrogen atom-containing monomer used is, for example, 40% by weight or less of the entire monomer component, 35% by weight or less, 30% by weight or less, or 25% by weight or less. good. In another aspect, the amount of the nitrogen atom-containing monomer used may be, for example, 20% by weight or less of the total monomer component, or 15% by weight or less. Alternatively, the nitrogen atom-containing monomer may not be used as the copolymerizable monomer.

The above copolymerizable monomer may contain a hydroxyl group-containing monomer. By using the hydroxyl group-containing monomer, the cohesive force of the photocurable pressure-sensitive adhesive layer (A) and the degree of cross-linking (for example, cross-linking with an isocyanate cross-linking agent) can be suitably adjusted. When a hydroxyl group-containing monomer is used, the amount used is not particularly limited, and may be, for example, 0.01% by weight or more, 0.1% by weight or more, or 0.5% by weight or more of the entire monomer component. It may be 1% by weight or more, 5% by weight or more, or 10% by weight or more. Further, from the viewpoint of suppressing water absorption of the photocurable pressure-sensitive adhesive layer (A) or the photocurable product thereof, in some embodiments, the amount of the hydroxyl group-containing monomer used is, for example, 40% by weight or less of the total monomer components. Is appropriate, and may be 30% by weight or less, 25% by weight or less, or 20% by weight or less. In another aspect, the amount of the hydroxyl group-containing monomer used may be, for example, 15% by weight or less of the total monomer component, 10% by weight or less, or 5% by weight or less. Alternatively, it is not necessary to use the hydroxyl group-containing monomer as the copolymerizable monomer.

The ratio of the carboxy group-containing monomer to the entire monomer component may be, for example, 2% by weight or less, 1% by weight or less, or 0.5% by weight or less (for example, less than 0.1% by weight). The pressure-sensitive adhesive composition (A) does not have to substantially contain a carboxy group-containing monomer as a constituent monomer component thereof. Here, the fact that the carboxy group-containing monomer is not substantially contained means that the carboxy group-containing monomer is not used at least intentionally. This can be advantageous from the viewpoint of the photocurable pressure-sensitive adhesive layer (A) formed from the pressure-sensitive adhesive composition (A) and the metal corrosion inhibitory property of the photo-curable product.

The above copolymerizable monomer may contain an alicyclic hydrocarbon group-containing (meth) acrylate. As a result, the cohesive force of the photocurable pressure-sensitive adhesive layer (A) can be enhanced, and the peel strength after photocuring can be improved. As the alicyclic hydrocarbon group-containing (meth) acrylate, those exemplified above can be used, and for example, cyclohexyl acrylate and isobornyl acrylate can be preferably adopted. When the alicyclic hydrocarbon group-containing (meth) acrylate is used, the amount used is not particularly limited, and may be, for example, 1% by weight or more, 3% by weight or more, or 5% by weight or more of the entire monomer component. In one aspect, the amount of the alicyclic hydrocarbon group-containing (meth) acrylate used may be 10% by weight or more of the total monomer component, or 15% by weight or more. It is appropriate that the upper limit of the amount of the alicyclic hydrocarbon group-containing (meth) acrylate used is approximately 40% by weight or less, for example, 30% by weight or less, and 25% by weight or less (for example, 15% by weight). % Or less, and even 10% by weight or less). Alternatively, the alicyclic hydrocarbon group-containing (meth) acrylate may not be used as the copolymerizable monomer.

The above copolymerizable monomer may contain an alkoxysilyl group-containing monomer. The alkoxysilyl group-containing monomer is typically an ethylenically unsaturated compound having at least one (preferably two or more, for example two or three) alkoxysilyl groups in one molecule, and examples thereof. Is as described above. The above-mentioned alkoxysilyl group-containing monomer may be used alone or in combination of two or more. By using the alkoxysilyl group-containing monomer, a crosslinked structure by a silanol group condensation reaction (silanol condensation) can be introduced into the photocurable pressure-sensitive adhesive layer (A).

The amount used when the alkoxysilyl group-containing monomer is used is not particularly limited. In some embodiments, the amount of the alkoxysilyl group-containing monomer used can be, for example, 0.005% by weight or more of the total monomer components constituting the pressure-sensitive adhesive composition (A), and usually 0.01% by weight. The above is appropriate, and may be 0.03% by weight or more, or 0.05% by weight or more. Further, from the viewpoint of step absorption of the pressure-sensitive adhesive composition (A), it is usually appropriate that the amount of the alkoxysilyl group-containing monomer used is 1.0% by weight or less of the total monomer component, and is 0.5. It may be 0% by weight or less, and may be 0.1% by weight or less.

Yet another example of the compound that can be used as the ethylenically unsaturated compound (B) is a polyfunctional monomer. According to the pressure-sensitive adhesive composition (A) containing a polyfunctional monomer, the polyfunctional monomer is reacted when the composition is cured to produce a photocurable pressure-sensitive adhesive layer (A). A photocurable pressure-sensitive adhesive layer (A) crosslinked with a functional monomer can be obtained. Examples of the polyfunctional monomer include 1,6-hexanediol di (meth) acrylate, 1,12-dodecanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, and polyethylene. Glycoldi (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, etc., 2 Functional Monomer; Polyfunctional Monomer with Trifunctionality or higher, such as Trimethylol Propanetri (Meta) Acrylate, Pentaerythritol Tri (Meta) Acrylate, Tetramethylol Methantri (Meta) Acrylate, Dipentaerythritol Hexa (Meta) Acrylate, etc. In addition, epoxy acrylate, polyester acrylate, urethane acrylate and the like; can be mentioned. Among them, preferred examples include 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipentaerythritol hexa (meth) acrylate. The polyfunctional monomer may be used alone or in combination of two or more.

When the polyfunctional monomer is used, the amount used is not particularly limited and may be less than 5.0% by weight of the total monomer component constituting the pressure-sensitive adhesive composition (A). This avoids the formation of an excessively crosslinked structure during the formation of the photocurable pressure-sensitive adhesive layer (A) (that is, at the stage before photo-curing), and the step of the photo-curable pressure-sensitive adhesive layer (A). Absorption can be enhanced. The amount of the polyfunctional monomer used may be, for example, 4.0% by weight or less of the total monomer component, 3.0% by weight or less, 2.0% by weight or less, or 1.0% by weight. It may be less than or equal to, 0.5% by weight or less, and may be 0.3% by weight or less. It is not necessary to use a polyfunctional monomer. Further, in some embodiments, the amount of the polyfunctional monomer used with respect to the entire monomer component is, for example, 0.001% by weight or more from the viewpoint of imparting appropriate cohesiveness to the photocurable pressure-sensitive adhesive layer (A). It may be 0.005% by weight or more, 0.01% by weight or more, or 0.03% by weight or more.

The weight ratio of the BP polymer (A) to the total amount of the BP polymer (A) and the ethylenically unsaturated compound (B) contained in the pressure-sensitive adhesive composition (A) is not particularly limited, and the pressure-sensitive adhesive composition is not particularly limited. It can be set so that the step absorption of the photocurable pressure-sensitive adhesive layer (A) formed from (A) and the processability of the photocurable product are suitably balanced. In some embodiments, the weight fraction of the BP polymer (A) may be, for example, 0.5% by weight or more, usually 1% by weight or more, preferably 1.5% by weight or more, more preferably 5. It is appropriate that it is 10% by weight or more, and from the viewpoint of enhancing the effect of photocuring, it may be 10% by weight or more, 15% by weight or more, 25% by weight or more, 35% by weight or more, or 45% by weight. The above may be sufficient, and 55% by weight or more may be used. Further, from the viewpoint of ease of preparation and coatability of the pressure-sensitive adhesive composition (A), in some embodiments, the weight ratio of the BP polymer (A) to the total amount is, for example, less than 99% by weight. It may be less than 95% by weight, less than 85% by weight, less than 70% by weight, less than 50% by weight, or less than 40% by weight.

The ratio of the weight of the organic solvent to the total weight of the pressure-sensitive adhesive composition (A) may be, for example, 30% by weight or less, preferably 20% by weight or less, and 10% by weight or less. It is preferable, and it is more preferable that it is 5% by weight or less. In some embodiments, the weight proportion of the organic solvent may be 3% by weight or less, 1% by weight or less, 0.5% by weight or less, 0.1% by weight or less, 0.05% by weight or less. % Or less, and it does not have to contain substantially an organic solvent.

The pressure-sensitive adhesive composition (A) is measured under the conditions of viscosity (BH type viscometer, No. 5 rotor, 10 rpm, measurement temperature of 30 ° C.) from the viewpoint of coatability in the normal temperature range. ) Is preferably 1000 Pa · s or less, preferably 100 Pa · s or less, and more preferably 50 Pa · s or less. The viscosity of the pressure-sensitive adhesive composition (A) may be, for example, 30 Pa · s or less, 20 Pa · s or less, 10 Pa · s or less, or 5 Pa · s or less. The lower limit of the viscosity of the pressure-sensitive adhesive composition (A) is not particularly limited, but is usually 0 from the viewpoint of suppressing the repelling of the pressure-sensitive adhesive composition within the coating range and the protrusion of the pressure-sensitive adhesive composition at the outer edge of the coating range. .1 Pa · s or more is appropriate, and may be 0.5 Pa · s or more, or 1 Pa · s or more.

The pressure-sensitive adhesive composition (A) contains at least a compound having one ethylenically unsaturated group (that is, a monofunctional monomer) (B1) as the ethylenically unsaturated compound (B). As the monofunctional monomer (B1), the corresponding compound can be selected and used from the above-mentioned examples of the ethylenically unsaturated compound (B). The monofunctional monomer may be used alone or in combination of two or more.

The weight ratio of the monofunctional monomer (B1) to the total amount of the BP polymer (A) and the ethylenically unsaturated compound (B) may be, for example, 1% by weight or more, or 5% by weight or more. It may be 15% by weight or more. In some embodiments, the weight ratio of the monofunctional monomer (B1) may be 25% by weight or more, or 35% by weight or more, from the viewpoint of ease of preparation and coatability of the pressure-sensitive adhesive composition (A). However, it may be 45% by weight or more. The weight ratio of the monofunctional monomer (B1) to the total amount is, for example, 99% by weight or less, usually 95% by weight or less, and 85% by weight or less. It may be 75% by weight or less, 65% by weight or less, 55% by weight or less, or 45% by weight or less.

In an embodiment in which the pressure-sensitive adhesive composition (A) contains a monofunctional monomer (B1), the glass transition temperature (Tg) determined by the Fox formula based on the composition of the monofunctional monomer (B1) is particularly limited. However, it can be, for example, −80 ° C. or higher and 250 ° C. or lower. The Tg based on the composition of the monofunctional monomer (B1) is usually preferably 150 ° C. or lower from the viewpoint of compatibility between the polymer derived from the monofunctional monomer (B1) and other components. It may be 100 ° C. or lower, 70 ° C. or lower, 50 ° C. or lower, or 30 ° C. or lower. In some embodiments, the Tg based on the composition of the monofunctional monomer (B1) is preferably less than 0 ° C., preferably −10 ° C., from the viewpoint of the step absorption of the photocurable pressure-sensitive adhesive layer (A). More preferably, it may be −20 ° C. or lower, −30 ° C. or lower, or −40 ° C. or lower. Further, from the viewpoint of the cohesiveness of the photocurable pressure-sensitive adhesive layer (A) and the processability after photocuring, it is usually advantageous that the Tg based on the composition of the monofunctional monomer (B1) is −60 ° C. or higher. It may be −54 ° C. or higher, −50 ° C. or higher, −45 ° C. or higher, −35 ° C. or higher, or −25 ° C. or higher. The Tg can be adjusted by the compound used as the monofunctional monomer and the usage ratio thereof.

In the pressure-sensitive adhesive composition (A) containing the BP polymer (A) and the monofunctional monomer (B1), the photocurable pressure-sensitive adhesive layer (A) formed from the pressure-sensitive adhesive composition, and the photo-cured product thereof, the BP polymer. The Tg (hereinafter, also referred to as Tg _B1 ) based on the monomer composition of the Tg (hereinafter referred to as “Tg _A ”) and the monofunctional monomer (B1) of (A) is Tg _B1 [° C.]-Tg _A [ The Tg difference [° C.] (hereinafter, also referred to as ΔTg) calculated by [° C.] can be set to be, for example, in the range of −50 ° C. or higher and 70 ° C. or lower. The fact that the absolute value of the Tg difference is not too large can be advantageous from the viewpoint of compatibility in the photocurable pressure-sensitive adhesive layer (A) and the photocurable product thereof. In some embodiments, ΔTg may be, for example, −10 ° C. or higher, preferably 0 ° C. or higher, 7 ° C. or higher, 10 ° C. or higher, 20 ° C. or higher, or 30 ° C. or higher. good.

The pressure-sensitive adhesive composition (A) may contain at least a compound having two or more ethylenically unsaturated groups (that is, a polyfunctional monomer) (B2) as the ethylenically unsaturated compound (B). The polyfunctional monomer (B2) can be used alone or in combination of two or more from the above-mentioned examples of the polyfunctional monomer. The amount of the polyfunctional monomer (B2) used can be set in the same manner as the ratio of the polyfunctional monomer to the entire monomer component constituting the pressure-sensitive adhesive composition (A).

In the embodiment in which the monofunctional monomer (B1) and the polyfunctional monomer (B2) are used in combination as the ethylenically unsaturated compound (B), the weight of the monofunctional monomer (B1) in the ethylenically unsaturated compound (B). The ratio may be, for example, 1% by weight or more, usually 25% by weight or more, 50% by weight or more, 75% by weight or more, 95% by weight or more, 99% by weight. It may be% or more. The weight ratio of the monofunctional monomer (B1) to the ethylenically unsaturated compound (B) may be, for example, 99.9% by weight or less, or 99.8% by weight or less.

In the pressure-sensitive adhesive composition (A), the ethylenically unsaturated compound (B) may be contained in the form of a partially polymerized product, or the entire amount thereof may be contained in the form of an unreacted monomer. The pressure-sensitive adhesive composition (A) according to a preferred embodiment contains the ethylenically unsaturated compound (B) in the form of a partial polymer. The polymerization method for partially polymerizing the ethylenically unsaturated compound (B) is not particularly limited, and for example: photopolymerization performed by irradiating light such as ultraviolet rays; radiation performed by irradiating radiation such as β-rays and γ-rays. Various conventionally known polymerization methods such as polymerization; thermal polymerization such as solution polymerization, emulsion polymerization, and bulk polymerization; can be appropriately selected and used. From the viewpoint of efficiency and convenience, the photopolymerization method can be preferably adopted. According to photopolymerization, the polymerization conversion rate (monomer conversion) can be easily controlled by the polymerization conditions such as the irradiation amount of light (light amount).

The polymerization conversion rate of the ethylenically unsaturated compound (B) in the above partial polymer is not particularly limited. From the viewpoint of ease of preparation and coatability of the pressure-sensitive adhesive composition (A), it is usually appropriate that the polymerization conversion rate is about 50% by weight or less, and about 40% by weight or less (for example, about 35% by weight). Weight% or less) is preferable. The lower limit of the polymerization conversion rate is not particularly limited, but is typically about 1% by weight or more, and usually about 5% by weight or more is appropriate.

The pressure-sensitive adhesive composition (A) containing a partial polymer of the ethylenically unsaturated compound (B) is, for example, a monomer mixture containing the entire amount of the ethylenically unsaturated compound (B) used in the preparation of the pressure-sensitive adhesive composition. It can be obtained by partial polymerization by an appropriate polymerization method (for example, a photopolymerization method). Further, the pressure-sensitive adhesive composition (A) containing a partial polymer of the ethylenically unsaturated compound (B) contains a part of the ethylenically unsaturated compound (B) used for preparing the pressure-sensitive adhesive composition. It may be a mixture of a partial polymer of a monomer mixture and the remaining ethylenically unsaturated compound (B) or a partial polymer thereof. In the present specification, the term "complete polymer" means that the polymerization conversion rate is more than 95% by weight.

The partial polymer can be prepared, for example, by irradiating the ethylenically unsaturated compound (B) with ultraviolet rays. When the partial polymer is prepared in the presence of the BP polymer (A), the ethylenically unsaturated group is reacted and the benzophenone structure is not photoexcited by setting the irradiation conditions of ultraviolet rays. A pressure-sensitive adhesive composition (A) containing a partial polymer of the compound (B) and a BP polymer (A) can be obtained. As the light source, a light source such as the above-mentioned black light or UV-LED lamp that does not contain a component having a wavelength of less than 300 nm or can irradiate ultraviolet rays having a small wavelength component can be preferably adopted.

Further, after preparing a partial polymer of the ethylenically unsaturated compound (B) in advance, the partial polymer and the BP polymer (A) may be mixed to prepare the pressure-sensitive adhesive composition (A). When the partial polymer is prepared by irradiating the ethylenically unsaturated compound (B) with ultraviolet rays in the absence of a benzophenone structure-containing component, the ultraviolet sources include a light source that does not excite the benzophenone structure and a light source that excites the benzophenone structure. Both can be used.

In the preparation of the partially polymer of the ethylenically unsaturated compound (B), the reaction of the ethylenically unsaturated group can be promoted by using a photopolymerization initiator. Examples of the photopolymerization initiator include a ketal-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, a benzoin ether-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, an α-ketol-based photopolymerization initiator, and an aromatic sulfonyl. Chloride-based photopolymerization initiator, photoactive oxime-based photopolymerization initiator, benzoin-based photopolymerization initiator, benzyl-based photopolymerization initiator, benzophenone-based photopolymerization initiator, alkylphenone-based photopolymerization initiator, thioxanthone-based photopolymerization initiator Agents and the like can be used. A photopolymerization initiator that absorbs light having a wavelength of 300 nm or more (for example, light having a wavelength of 300 nm or more and 500 nm or less) to generate radicals can be preferably adopted. As the photopolymerization initiator, one type may be used alone or two or more types may be used in combination as appropriate.

[Photopolymerization initiator]
The pressure-sensitive adhesive composition (A) may contain a photopolymerization initiator, if necessary, for the purpose of improving or imparting photocurability. When the pressure-sensitive adhesive composition (A) is a solvent-free type (active energy ray-curable type) pressure-sensitive adhesive composition, the pressure-sensitive adhesive composition (A) preferably contains a photopolymerization initiator. On the other hand, when the pressure-sensitive adhesive composition (A) is a solvent-type or emulsion-type pressure-sensitive adhesive composition, it does not have to contain a photopolymerization initiator.

Examples of the photopolymerization initiator include a ketal-based photopolymerization initiator, an acetophenone-based photopolymerization initiator, a benzoin ether-based photopolymerization initiator, an acylphosphine oxide-based photopolymerization initiator, an α-ketol-based photopolymerization initiator, and an aromatic sulfonyl. Chloride-based photopolymerization initiator, photoactive oxime-based photopolymerization initiator, benzoin-based photopolymerization initiator, benzyl-based photopolymerization initiator, benzophenone-based photopolymerization initiator, alkylphenone-based photopolymerization initiator, thioxanthone-based photopolymerization initiator Agents and the like can be used. As the photopolymerization initiator, one type may be used alone or two or more types may be used in combination as appropriate.

Specific examples of the ketal-based photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one and the like.
Specific examples of the acetophenone-based photopolymerization initiator include 1-hydroxycyclohexyl-phenyl-ketone, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1- [4- (2-hydroxyethoxy) -phenyl]. -2-Hydroxy-2-methyl-1-propane-1-one, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, methoxyacetophenone and the like are included.
Specific examples of the benzoin ether-based photopolymerization initiator include benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether and benzoin isobutyl ether, and substituted benzoin ethers such as anisole methyl ether.
Specific examples of the acylphosphine oxide-based photopolymerization initiator include bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -2,4-di-n-butoxy. Includes phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and the like.
Specific examples of the α-ketol-based photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1- [4- (2-hydroxyethyl) phenyl] -2-methylpropane-1-one and the like. Is done.
Specific examples of the aromatic sulfonyl chloride-based photopolymerization initiator include 2-naphthalene sulfonyl chloride and the like.
Specific examples of the photoactive oxime-based photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime and the like.
Specific examples of the benzoin-based photopolymerization initiator include benzoin and the like.
Specific examples of the benzyl-based photopolymerization initiator include benzyl and the like.
Specific examples of the benzophenone-based photopolymerization initiator include benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexylphenylketone and the like.
Specific examples of the thioxanthone-based photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and isopropylthioxanthone. , 2,4-Diisopropylthioxanthone, dodecylthioxanthone and the like.

As the photopolymerization initiator contained in the pressure-sensitive adhesive composition (A), a photopolymerization initiator that absorbs light having a wavelength of 300 nm or more (for example, light having a wavelength of 300 nm or more and 500 nm or less) to generate a radical (“photopolymerization initiator”). (C) ”) may be preferably adopted. When the pressure-sensitive adhesive composition (A) contains a photopolymerization initiator (C), it is preferable to cure the pressure-sensitive adhesive composition (A) into a cured product in which the benzophenone structure of the BP polymer (A) remains.

As the photopolymerization initiator, one type can be used alone or two or more types can be used in combination as appropriate. In some embodiments, a photopolymerization initiator that does not contain a phosphorus element in the molecule can be preferably adopted. The pressure-sensitive adhesive composition (A) may be substantially free of a photopolymerization initiator containing a phosphorus element in the molecule.

The content of the photopolymerization initiator in the pressure-sensitive adhesive composition (A) is not particularly limited, and can be set so as to appropriately exert the desired effect. In some embodiments, the content of the photopolymerization initiator can be, for example, approximately 0.005 parts by weight or more with respect to 100 parts by weight of the monomer component constituting the pressure-sensitive adhesive composition (A), and is usually used. It is appropriate to have 0.01 parts by weight or more, preferably 0.05 parts by weight or more, 0.10 parts by weight or more, 0.15 parts by weight or more, and 0.20 parts by weight. It may be more than a part. By increasing the content of the photopolymerization initiator, the photocurability of the pressure-sensitive adhesive composition (A) is improved. Further, the content of the photopolymerization initiator with respect to 100 parts by weight of the monomer component constituting the pressure-sensitive adhesive composition (A) is usually preferably 5 parts by weight or less, preferably 2 parts by weight or less. It may be 1 part by weight or less, 0.7 parts by weight or less, or 0.5 part by weight or less. It may be advantageous from the viewpoint of suppressing gelation of the pressure-sensitive adhesive composition (A) that the content of the photopolymerization initiator is not too large.

[Crosslinking agent]
The pressure-sensitive adhesive composition (A) may contain, for example, an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an oxazoline-based cross-linking agent, an aziridine-based cross-linking agent, a carbodiimide-based cross-linking agent, a melamine-based cross-linking agent, and a urea-based cross-linking agent. , A known cross-linking agent such as a metal alkoxide-based cross-linking agent, a metal chelate-based cross-linking agent, a metal salt-based cross-linking agent, a hydrazine-based cross-linking agent, and an amine-based cross-linking agent can be blended. Peroxide may be used as a cross-linking agent. When the pressure-sensitive adhesive composition (A) is a solvent-type or emulsion-type pressure-sensitive adhesive composition, it preferably contains a cross-linking agent.

The above-mentioned cross-linking agent can be used alone or in combination of two or more. The photocurable pressure-sensitive adhesive layer (A) formed from the pressure-sensitive adhesive composition (A) containing a cross-linking agent preferably contains the cross-linking agent mainly in the form after the cross-linking reaction. By using the cross-linking agent, the cohesive force of the photocurable pressure-sensitive adhesive layer (A) can be appropriately adjusted.

The amount used when a cross-linking agent is used (when two or more kinds of cross-linking agents are used, the total amount thereof) is not particularly limited. From the viewpoint of realizing a pressure-sensitive adhesive that exhibits a well-balanced adhesive property such as adhesive force and cohesive force, the amount of the cross-linking agent used is usually 100 parts by weight of the monomer component constituting the pressure-sensitive adhesive composition (A). It is appropriate that it is about 5 parts by weight or less, and it may be 3 parts by weight or less, 1 part by weight or less, 0.50 parts by weight or less, 0.30 parts by weight or less, and 0. It may be 20 parts by weight or less. The lower limit of the amount of the cross-linking agent used is not particularly limited, and may be more than 0 parts by weight with respect to 100 parts by weight of the monomer component constituting the pressure-sensitive adhesive composition (A). In some embodiments, the amount of the cross-linking agent used may be, for example, 0.001 part by weight or more, and 0.01 part by weight or more, based on 100 parts by weight of the monomer component constituting the pressure-sensitive adhesive composition (A). However, it may be 0.05 parts by weight or more, or 0.10 parts by weight or more.

[Chain transfer agent]
The pressure-sensitive adhesive composition (A) may contain various conventionally known chain transfer agents. As the chain transfer agent, mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, thioglycolic acid, and α-thioglycerol can be used. Alternatively, a chain transfer agent containing no sulfur atom (non-sulfur chain transfer agent) may be used. Specific examples of the non-sulfur chain transfer agent include anilines such as N, N-dimethylaniline and N, N-diethylaniline; terpenoids such as α-pinene and turpinolene; α-methylstyrene and α-methylstyrene dimer. Stylines such as; compounds having a benzidenyl group such as dibenzylidene acetone, cinnamyl alcohol, cinnamyl aldehyde; hydroquinones such as hydroquinone and naphthohydroquinone; quinones such as benzoquinone and naphthoquinone; 2,3-dimethyl-2-butene , 1,5-Cyclooctadiene and the like; alcohols such as phenol, benzyl alcohol and allyl alcohol; benzyl hydrogens such as diphenylbenzene and triphenylbenzene; and the like. The chain transfer agent may be used alone or in combination of two or more. When a chain transfer agent is used, the amount used may be, for example, about 0.01 to 1 part by weight with respect to 100 parts by weight of the monomer component. It can also be preferably carried out in an embodiment in which a chain transfer agent is not used.

Another component that can be contained in the pressure-sensitive adhesive composition (A) is a silane coupling agent. The use of a silane coupling agent can improve the peel strength against an adherend (eg, a glass plate). Further, the photocurable pressure-sensitive adhesive layer (A) can contain a silane coupling agent. The photocurable pressure-sensitive adhesive layer (A) containing a silane coupling agent can be suitably formed by using the pressure-sensitive adhesive composition (A) containing a silane coupling agent. The silane coupling agent may be used alone or in combination of two or more.

The pressure-sensitive adhesive composition (A) is, if necessary, a pressure-sensitive adhesive resin (for example, a rosin-based, petroleum-based, terpene-based, phenol-based, ketone-based or other tack-imparting resin), a viscosity modifier (for example, a thickener). , Leveling agents, antioxidants, plasticizers, fillers, stabilizers, preservatives, antioxidants and the like, which may include various additives common in the field of adhesives as other optional ingredients. As for such various additives, conventionally known additives can be used by a conventional method and do not particularly characterize the present invention, and therefore detailed description thereof will be omitted.

The pressure-sensitive adhesive composition (A) can exhibit good adhesive strength without using the above-mentioned pressure-sensitive adhesive resin. Therefore, in some embodiments, the content of the tackifier resin in the photocurable pressure-sensitive adhesive layer (A) or the pressure-sensitive adhesive composition (A) is, for example, 10 parts by weight with respect to 100 parts by weight of the monomer component. It can be less than, or even less than 5 parts by weight. The content of the tackifier resin may be less than 1 part by weight (for example, less than 0.5 parts by weight) or less than 0.1 parts by weight (0 parts by weight or more and less than 0.1 parts by weight). good. The photocurable pressure-sensitive adhesive layer (A) or the pressure-sensitive adhesive composition (A) may not contain a tackifier resin.

[Photo-curable adhesive layer (A)]
The photocurable pressure-sensitive adhesive layer (A) is a cured product of the pressure-sensitive adhesive composition (A) and is formed of a cured product in which a benzophenone structure remains. This benzophenone structure can form a crosslinked structure by irradiation with ultraviolet rays to cure the photocurable pressure-sensitive adhesive layer (A). The photocurable pressure-sensitive adhesive layer (A) before curing is in a semi-cured state with high fluidity and exhibits excellent step absorption. Therefore, when the photocurable pressure-sensitive adhesive layer (A) of the photo-curable pressure-sensitive adhesive sheet (A) is bonded to a display panel in which light-emitting elements (LED chips) are densely arranged, the space between the light-emitting elements (LED chips). It fully follows the minute steps of the LED and adheres without any gaps without leaving any bubbles. On the other hand, the photocurable pressure-sensitive adhesive layer (A) after curing exhibits excellent processability. Therefore, when the laminated body containing the photocurable pressure-sensitive adhesive layer (A) after curing is cut, the adhesive is chipped, and when stored, the pressure-sensitive adhesive layer is suppressed from protruding from the end and dripping. As described above, according to the photocurable pressure-sensitive adhesive layer (A) composed of the cured product of the pressure-sensitive adhesive composition (A), excellent step absorption and processability can be suitably compatible with each other. ..

The method for producing the photocurable pressure-sensitive adhesive layer (A) is not particularly limited, but it can be produced, for example, by irradiating the pressure-sensitive adhesive composition (A) with active energy rays, heating and drying, and the like. Specifically, the pressure-sensitive adhesive composition (A) may be applied (coated) on a base material or a release liner, and dried, cured, or dried and cured, if necessary.

A known coating method may be used for applying (coating) the pressure-sensitive adhesive composition (A). For example, a coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, or a direct coater may be used.

When the pressure-sensitive adhesive composition (A) is cured by irradiation with active energy rays, the ethylenically unsaturated group contained in the pressure-sensitive adhesive composition (A) is reacted and the photo-curable pressure-sensitive adhesive layer (A) is reacted. It is preferable that the benzophenone structure contained in the above is retained. As the active energy ray for forming the photocurable pressure-sensitive adhesive layer (A), ultraviolet rays are preferable, and ultraviolet rays containing no component having a wavelength of less than 300 nm or having a small wavelength component are more preferable.

When the pressure-sensitive adhesive composition (A) contains the BP polymer (A) and the ethylenically unsaturated compound (B), the photocurable pressure-sensitive adhesive layer (A) has the BP polymer (A) and the ethylenically unsaturated compound (B). It may contain a polymer (E) derived from the compound (B). In this embodiment, the pressure-sensitive adhesive composition (A) may have a composition in which the ethylenically unsaturated compound (B) does not contain the ethylenically unsaturated BP. According to the pressure-sensitive adhesive composition (A) having such a composition, the BP polymer (A) and the polymer (E) derived from the ethylenically unsaturated compound (B) are contained, and the polymer (E) has a benzophenone structure. A photocurable pressure-sensitive adhesive layer (A), which is a polymer (sometimes referred to as a [non-BP polymer]), can be produced.

On the other hand, when the pressure-sensitive adhesive composition (A) contains a mixture of the monomer components constituting the BP polymer (A) or a partial polymer of the mixture of the monomer components, the photocurable pressure-sensitive adhesive layer (A) has a monomer composition. Photocurable, which comprises two or more different polymers and at least one of the two or more polymers has a benzophenone structure in the side chain (sometimes referred to as "BP polymer (A')"). It can be a pressure-sensitive adhesive layer. The photocurable pressure-sensitive adhesive layer may contain only two or more types of BP polymers (A') as the two or more types of polymers, and may contain a combination of a non-BP polymer and a BP polymer (A'). You may be. The non-BP polymer can be formed by polymerizing the ethylenically unsaturated compound using a pressure-sensitive adhesive composition containing an ethylenically unsaturated compound having no benzophenone structure. The BP polymer (A') may be, for example, the BP polymer (A) contained in the pressure-sensitive adhesive composition (A), or may be a modified product thereof, and the pressure-sensitive adhesive composition (A). It may be formed by copolymerizing the ethylenically unsaturated BP contained in A) with another ethylenically unsaturated BP.
The above two or more kinds of polymers may or may not be chemically bonded. The photocurable pressure-sensitive adhesive layer (A) according to some embodiments may contain at least one BP polymer in a form that is not chemically bonded to a polymer other than the BP polymer.

It is preferable that the irradiation of the active energy ray for curing the pressure-sensitive adhesive composition (A) is carried out so as to react the ethylenically unsaturated group and leave the benzophenone structure. As the pressure-sensitive adhesive composition (A), a pressure-sensitive adhesive composition containing the BP polymer (A) and the ethylenically unsaturated compound (B) can be preferably used. The light source for curing the pressure-sensitive adhesive composition (A) to form a photocrosslinkable pressure-sensitive adhesive does not contain a component having a wavelength of less than 300 nm, such as the above-mentioned black light or UV-LED lamp, or the wavelength component is used. A light source capable of irradiating a small amount of ultraviolet rays can be preferably adopted.

In a preferred embodiment of the present invention, the photocurable pressure-sensitive adhesive layer (A) has a maximum transmittance at a wavelength of 200 to 400 nm (preferably a wavelength of 330 to 400 nm) and a maximum transmittance at a wavelength of 400 to 700 nm. Greater than. The photocurable adhesive layer (A), which has excellent light-shielding properties against visible light, has no gaps between the metal wiring layer of the self-luminous display device (mini / micro LED display device) and the light-emitting element (LED chip). By sealing, reflection due to metal wiring or the like is prevented, color mixing of the light emitting element (LED chip) is prevented, and image contrast is improved. On the other hand, in the photocurable pressure-sensitive adhesive layer (A) having a high transmittance in the ultraviolet region (wavelength 200 to 400 nm, preferably wavelength 330 to 400 nm), the benzophenone structure forms a crosslinked structure and is cured by irradiation with ultraviolet rays. As a result, the workability is improved, and the adhesive chipping during the cutting process and the protrusion and sagging of the adhesive layer from the end portion during storage are suppressed.

Further, in a preferred embodiment of the present invention, the maximum value of the transmittance of the photocurable pressure-sensitive adhesive layer (A) at a wavelength of 400 to 700 nm (visible light region) is, for example, 80% or less, 70% or less, 60. % Or less, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less.

Further, in a preferred embodiment of the present invention, the photocurable pressure-sensitive adhesive layer (A) has an average transmittance at a wavelength of 200 to 400 nm (preferably a wavelength of 330 to 400 nm) rather than an average transmittance at a wavelength of 400 to 700 nm. big. The average transmittance of the photocurable pressure-sensitive adhesive layer (A) at a wavelength of 400 to 700 nm (visible light region) is, for example, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, and 30%. Below, it may be 20% or less, 10% or less, or 5% or less.

The photocurable pressure-sensitive adhesive layer (A) preferably contains, for example, about 0.1 mg or more of a benzophenone structure in terms of 4-benzoylphenyl acrylate, per 1 g of the pressure-sensitive adhesive layer. Hereinafter, the weight of the benzophenone structure in terms of 4-benzoylphenyl acrylate contained in 1 g of the photocurable pressure-sensitive adhesive layer (A) may be referred to as the BP equivalent (unit: mg / g) of the pressure-sensitive adhesive layer. From the viewpoint of obtaining a higher photocuring effect (for example, the effect of enhancing processability by photocuring), the BP equivalent of the pressure-sensitive adhesive layer is usually preferably 0.3 mg / g or more, and is 0.5 mg / g. It may be g or more, 1 mg / g or more, 5 mg / g or more, 10 mg / g or more, or 20 mg / g or more. Further, from the viewpoint of impact resistance of the joint portion by the photo-cured product and suppression of strain in the photo-cured product, the BP equivalent of the pressure-sensitive adhesive layer is usually preferably 100 mg / g or less, and 80 mg / g or less. It may be 60 mg / g or less, 40 mg / g or less, 25 mg / g or less, or 15 mg / g or less.

(Storage modulus)
The storage elastic modulus (G'b85) of the photocurable pressure-sensitive adhesive layer (A) before curing at 85 ° C. is not particularly limited, but is, for example, preferably less than 65 kPa, more preferably 60 kPa or less, still more preferably 55 kPa or less. Particularly preferably, it may be 50 kPa or less, and further may be 45 kPa or less. Such a configuration is preferable in order to realize excellent step absorption of the photocurable pressure-sensitive adhesive layer (A) before curing. Further, G'b85 is not particularly limited, but is preferably 5 kPa or more, more preferably 10 kPa or more, still more preferably 15 kPa or more, for example, from the viewpoint of handleability and workability. The storage elasticity (G'b85) of the photocurable pressure-sensitive adhesive layer (A) before curing at 85 ° C. is the composition of the pressure-sensitive adhesive composition (A) (for example, Mw, Tg; BP polymer of the BP polymer (A)). The weight fraction of (A); the composition of the monomer components constituting the BP polymer (A) and the ethylenically unsaturated compound (B), the type and amount of the functional group; the type and amount of the cross-linking agent) can be adjusted. can.

The storage elastic modulus (G'a10) of the photocurable pressure-sensitive adhesive layer (A) after curing at 10 ° C. is not particularly limited, but is, for example, preferably 90 kPa or more, more preferably 100 kPa or more, and more preferably 110 kPa or more. It may be more preferably 120 kPa or more, more preferably 130 kPa or more, more preferably larger than 146 kPa, still more preferably 180 kPa or more, still more preferably 200 kPa or more, particularly preferably 250 kPa or more, further 300 kPa or more, or 350 kPa or more. Such a configuration is preferable in order to realize excellent processability of the photocurable pressure-sensitive adhesive layer (A) after curing. Further, G'a10 is not particularly limited, but is, for example, 5000 kPa or less, preferably 2500 kPa or less, and more preferably 1000 kPa or less from the viewpoint of adhesive reliability. The storage elasticity (G'a10) of the photocurable pressure-sensitive adhesive layer (A) after curing at 10 ° C. is the composition of the pressure-sensitive adhesive composition (A) (for example, Mw, Tg, BP equivalent of the BP polymer (A)). Adjusted by weight fraction of BP polymer (A); composition of monomer components constituting BP polymer (A) and ethylenically unsaturated compound (B), type and amount of functional group; type and amount of cross-linking agent), etc. can do.

The storage elastic modulus (G'a10) of the photocurable pressure-sensitive adhesive layer (A) after curing at 10 ° C. with respect to the storage elastic modulus (G'b85) of the photo-curable pressure-sensitive adhesive layer (A) before curing at 85 ° C. The ratio (G'a10 / G'b85) is not particularly limited, but is, for example, preferably larger than 2.8, more preferably 2.9 or more, still more preferably 3 or more, particularly preferably 3.1 or more, and further. Is 3.2 or more, 3.3 or more, greater than 3.3, 3.4 or more, 3.5 or more, 3.6 or more, 3.7 or more, 3.8 or more, 3.9 or more, 4 or more, It may be 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, or 11 or more. Such a configuration is preferable in that it can achieve both excellent step absorption of the photocurable pressure-sensitive adhesive layer (A) before curing and excellent processability of the photo-curable pressure-sensitive adhesive layer (A) after curing. The G'a10 / G'b85 is not particularly limited, but is preferably 100 or less, more preferably 50 or less, still more preferably 30 or less, for example, from the viewpoint of handleability, workability, and adhesive reliability. be. The storage elasticity (G'a10) of the photocurable pressure-sensitive adhesive layer (A) after curing at 10 ° C. with respect to the storage elasticity (G'b85) of the photocurable pressure-sensitive adhesive layer (A) before curing at 85 ° C. The ratio (G'a10 / G'b85) is the composition of the pressure-sensitive adhesive composition (A) (eg, Tg, Mw, BP equivalent of BP polymer (A); weight fraction of BP polymer (A); BP polymer (eg). It can be adjusted by the composition of the monomer component constituting A) and the ethylenically unsaturated compound (B), the type and amount of the functional group; the type and amount of the cross-linking agent) and the like.

The storage elastic modulus (G'b10) of the photocurable pressure-sensitive adhesive layer (A) before curing at 10 ° C. is not particularly limited, but is preferably, for example, 10 kPa or more from the viewpoint of handleability and workability. It may be preferably 50 kPa or more, more preferably 70 kPa or more, or 90 kPa or more, 100 kPa or more. Further, G'b10 is not particularly limited, but is, for example, 5000 kPa or less, preferably 2500 kPa or less, and more preferably 1000 kPa or less from the viewpoint of adhesive reliability. The storage elasticity (G'b10) of the photocurable pressure-sensitive adhesive layer (A) before curing at 10 ° C. is the composition of the pressure-sensitive adhesive composition (A) (for example, Mw, Tg; BP polymer of the BP polymer (A)). The weight fraction of (A); the composition of the monomer components constituting the BP polymer (A) and the ethylenically unsaturated compound (B), the type and amount of the functional group; the type and amount of the cross-linking agent) can be adjusted. can.

The storage elastic modulus (G'a85) of the photocurable pressure-sensitive adhesive layer (A) after curing at 85 ° C. is not particularly limited, but is preferably, for example, preferably 10 kPa or more from the viewpoint of handleability and workability. Is 20 kPa or more, more preferably 30 kPa or more. Further, G'a85 is not particularly limited, but is, for example, 1000 kPa or less, preferably 500 kPa or less, and more preferably 200 kPa or less from the viewpoint of adhesive reliability. The storage elasticity (G'a85) of the photocurable pressure-sensitive adhesive layer (A) after curing at 85 ° C. is the composition of the pressure-sensitive adhesive composition (A) (for example, Mw, Tg, BP equivalent of the BP polymer (A)). Adjusted by weight fraction of BP polymer (A); composition of monomer components constituting BP polymer (A) and ethylenically unsaturated compound (B), type and amount of functional group; type and amount of cross-linking agent), etc. can do.

The storage elastic modulus (G'a25) of the photocurable pressure-sensitive adhesive layer (A) after curing at 25 ° C. is not particularly limited, but is, for example, preferably 70 kPa or more, more preferably larger than 100 kPa, and more preferably 150 kPa or more. , More preferably 170 kPa or more. Such a configuration is preferable in order to realize excellent processability of the photocurable pressure-sensitive adhesive layer (A) after curing. The G'a25 is not particularly limited, but is, for example, 5000 kPa or less, preferably 2500 kPa or less, and more preferably 1000 kPa or less from the viewpoint of adhesive reliability. The storage elasticity (G'a25) of the photocurable pressure-sensitive adhesive layer (A) after curing at 25 ° C. is the composition of the pressure-sensitive adhesive composition (A) (for example, Mw, Tg, BP equivalent of the BP polymer (A)). Adjusted by weight fraction of BP polymer (A); composition of monomer components constituting BP polymer (A) and ethylenically unsaturated compound (B), type and amount of functional group; type and amount of cross-linking agent), etc. can do.

The storage elastic modulus (G'b25) of the photocurable pressure-sensitive adhesive layer (A) before curing at 25 ° C. is not particularly limited, but is, for example, 300 kPa or less, preferably 250 kPa or less, and more preferably 200 kPa or less. Such a configuration is preferable in order to realize excellent step absorption of the photocurable pressure-sensitive adhesive layer (A) before curing. Further, G'b25 is not particularly limited, but from the viewpoint of adhesive reliability, for example, it is preferably 10 kPa or more, more preferably 30 kPa or more, still more preferably 50 kPa or more. The storage elasticity (G'b25) of the photocurable pressure-sensitive adhesive layer (A) before curing at 25 ° C. is the composition of the pressure-sensitive adhesive composition (A) (for example, Mw, Tg; BP polymer of the BP polymer (A)). The weight fraction of (A); the composition of the monomer components constituting the BP polymer (A) and the ethylenically unsaturated compound (B), the type and amount of the functional group; the type and amount of the cross-linking agent) can be adjusted. can.

The ratio (G'a25) of the storage elastic modulus (G'a25) of the cured pressure-sensitive adhesive layer A at 25 ° C. to the storage elastic modulus (G'b85) of the photocurable pressure-sensitive adhesive layer (A) before curing at 85 ° C. / G'b85) is not particularly limited, but is, for example, preferably 0.3 or more, more preferably 0.5 or more, more preferably 1 or more, more preferably larger than 3, and preferably 3.5 or more. It is preferably 4 or more. Such a configuration is preferable in that both the excellent step absorption of the pressure-sensitive adhesive layer A before curing and the excellent processability of the pressure-sensitive adhesive layer A after curing can be achieved at the same time. The G'a25 / G'b85 is not particularly limited, but is, for example, 100 or less, preferably 50 or less, and more preferably 30 or less from the viewpoint of handleability, workability, and adhesive reliability. The ratio (G'a25) of the storage elasticity (G'a25) of the cured pressure-sensitive adhesive layer A at 25 ° C. to the storage elasticity (G'b85) of the photocurable pressure-sensitive adhesive layer (A) before curing at 85 ° C. / G'b85) is the composition of the pressure-sensitive adhesive composition (A) (eg, Mw, Tg, BP equivalent of BP polymer (A); weight fraction of BP polymer (A); BP polymer (A) and ethylenicity. It can be adjusted by the composition of the monomer component constituting the unsaturated compound (B), the type and amount of the functional group; the type and amount of the cross-linking agent) and the like.

The curing conditions in the above-mentioned "photocurable pressure-sensitive adhesive layer (A) after curing" are not particularly limited, but ultraviolet rays in which the pressure-sensitive adhesive layer (A) exhibits transparency are preferable. It is more preferably ultraviolet rays having a wavelength of 200 to 400 nm, and further preferably ultraviolet rays having a wavelength of less than 300 nm. As the light source for irradiating ultraviolet rays, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, a microwave-excited lamp, a metal halide lamp, a chemical lamp, a black light, or an LED can be used. In addition, the irradiation energy, irradiation time, and irradiation method of the radiation for curing should be appropriately set as long as the photocurable pressure-sensitive adhesive layer (A) can be cured and the adherend is not unduly affected. Can be done. For example, when ultraviolet rays are used as the curing radiation, the irradiation amount (integrated light amount) is preferably 1000 mJ / cm ² to 10000 mJ / cm ² , more preferably 2000 mJ / cm ² to 4000 mJ / cm ² , and further. It is preferably 3000 mJ / cm ² .
Further, the storage elastic modulus is measured by dynamic viscoelasticity measurement.

[VOC emission amount]
The amount of VOC (volatile organic compound) emitted from the photocurable pressure-sensitive adhesive layer (A) is not particularly limited. The VOC emission amount may be, for example, 5000 μg / g or less, 3000 μg / g or less, or 1000 μg / g or less. In some embodiments, the VOC emission amount of the photocurable pressure-sensitive adhesive layer (A) is preferably 500 μg / g or less, more preferably 300 μg / g or less, and more preferably 100 μg / g or less. More preferred. The photocurable pressure-sensitive adhesive layer (A) having a small VOC emission amount has a low odor and is preferable from the viewpoint of environmental hygiene. The small amount of VOC emitted from the photocurable pressure-sensitive adhesive layer (A) is also from the viewpoint of suppressing foaming due to volatile organic compounds (VOC) in the photo-curable pressure-sensitive adhesive layer (A) and low contamination. preferable. The amount of VOC emitted from the photocurable pressure-sensitive adhesive layer (A) is measured by the following method using an appropriate amount of the photo-curable pressure-sensitive adhesive layer (A) (for example, about 1 mg to 2 mg) as a measurement sample. The thickness of the measurement sample is preferably 1 mm or less.

[VOC measurement test]
Place the measurement sample in a 20 mL vial and seal it tightly. Next, the vial is heated at 80 ° C. for 30 minutes, and 1.0 mL (sample gas) of the heated gas is injected into a gas chromatograph (GC) measuring device using a headspace autosampler (HSS). Based on the obtained gas chromatogram, the amount of gas generated from the above-mentioned measurement sample is determined as an n-decane equivalent amount. From the obtained values, the VOC emission amount (μg / g) per 1 g of the measurement sample is determined. The n-decane conversion amount is obtained by regarding the detection intensity of the generated gas obtained by GC Mass as the detection intensity of n-decane and applying a calibration curve of n-decane prepared in advance. The settings of HSS and GC are as follows.
HSS: Agilent Technologies, model "7694"
Heating time: 30 minutes Pressurization time: 0.12 minutes Loop filling time: 0.12 minutes Loop equilibrium time: 0.05 minutes Injection time: 3 minutes Sample loop temperature: 160 ° C.
Transfer line temperature: 200 ° C
GC device: Made by Agilent Technologies, model "6890"
Column: J & W capillary column manufactured by GL Sciences, Ltd. Product name "DB-ffAP" (inner diameter 0.533 mm x length 30 m, film thickness 1.0 μm)
Column temperature: 250 ° C (heat up from 40 ° C to 90 ° C at 10 ° C / min, then heat up to 250 ° C at 20 ° C / min and hold for 5 minutes)
Column pressure: 24.3 kPa (constant flow mode)
Carrier gas: Helium (5.0 mL / min)
Injection: Split (split ratio 12: 1)
Injection port temperature: 250 ° C
Detector: FID
Detector temperature: 250 ° C

In general, examples of the volatile organic compound that can be a factor that increases the VOC emission amount of the pressure-sensitive adhesive include an organic solvent (for example, a residue of the organic solvent contained in the pressure-sensitive adhesive composition (A)) and the pressure-sensitive adhesive composition. Examples thereof include an unreacted product of an ethylenically unsaturated compound contained in the product (for example, an unpolymerized acrylic monomer; hereinafter, also referred to as “residual monomer”). The photocurable pressure-sensitive adhesive layer (A) may be such that the content of such an organic solvent or residual monomer is suppressed to such an extent that it satisfies any of the above-mentioned VOC emission amounts. Although the photocurable pressure-sensitive adhesive layer (A) has a structure in which the amount of residual monomers is limited as described above, it is possible to form a new crosslink in the system by utilizing the benzophenone structure of the BP polymer (A). This makes it possible to form a photo-cured product with improved workability.
In principle, the lower the VOC emission amount of the photocurable pressure-sensitive adhesive layer (A) disclosed here is, the more preferable it is. The emission amount may be, for example, 10 μg / g or more, 30 μg / g or more, 80 μg / g or more, 150 μg / g or more, or 200 μg / g or more.
The amount of VOC emitted from the photocurable pressure-sensitive adhesive layer (A) is determined by the composition of the pressure-sensitive adhesive composition (A) (for example, the composition of the monomer components constituting the BP polymer (A) and the ethylenically unsaturated compound (B), and the organic composition. It can be adjusted by the amount of the solvent), the curing conditions (heating conditions, ultraviolet irradiation conditions) of the pressure-sensitive adhesive composition (A), and the like.

(Gel fraction)
The gel fraction of the photocurable pressure-sensitive adhesive layer (A) is not particularly limited, but the cohesiveness of the photo-curable pressure-sensitive adhesive layer (A) and the handling of the pressure-sensitive adhesive sheet having the photo-curable pressure-sensitive adhesive layer (A). From the viewpoint of sex and the like, it is usually appropriate that it is 5% or more, preferably 15% or more, 25% or more, or 35% or more. The gel fraction of the photocurable pressure-sensitive adhesive layer (A) is 100% or less in principle. Further, from the viewpoint of step absorption with respect to the surface shape of the adherend, the gel fraction of the photocurable pressure-sensitive adhesive layer (A) is preferably less than 85%, may be less than 70%, or may be less than 55%. Well, it may be less than 40%.

The gel fraction is measured by the following method. That is, a measurement sample of about 0.5 g is precisely weighed, and the weight thereof is defined as W1. This measurement sample is wrapped in a porous PTFE (polytetrafluoroethylene) sheet, immersed in ethyl acetate for 1 week at room temperature, dried, and the weight W2 of the ethyl acetate insoluble matter is measured. formula:
Gel fraction (%) = W2 / W1 × 100;
Substitute in to calculate the gel fraction. As the porous PTFE sheet, the trade name "Nitoflon NTF1122" manufactured by Nitto Denko Co., Ltd. or an equivalent product thereof can be used.

In some embodiments of the photocurable pressure-sensitive adhesive layer (A), ultraviolet rays are applied to the photo-curable pressure-sensitive adhesive layer (A) under the conditions of an illuminance of 300 mW / cm ² and an integrated light amount of 10,000 mJ / cm ² using a high-pressure mercury lamp. The gel content of the photocured product obtained by irradiation may be, for example, 70% or more, preferably 90% or more, 95% or more, or 98% or more. In principle, the gel fraction of the photocured product is 100% or less. The gel fraction is measured by the method described above.
The gel fraction of the photocurable pressure-sensitive adhesive layer (A) is the composition of the pressure-sensitive adhesive composition (A) (for example, Mw, Tg, BP equivalent of the BP polymer (A); the weight fraction of the BP polymer (A); Composition of monomer components constituting BP polymer (A) and ethylenically unsaturated compound (B), type and amount of functional group; type and amount of cross-linking agent), pressure-sensitive adhesive composition (A), photocurable pressure-sensitive adhesive It can be adjusted by the curing conditions (heating conditions, ultraviolet irradiation conditions) of the layer (A) and the like.

The glass transition point (Tg) of the photocurable pressure-sensitive adhesive layer (A) is not particularly limited, but is preferably -60 to 20 ° C, more preferably -40 to 10 ° C, and even more preferably -40 to 10 ° C. It is -30 to 0 ° C. If the Tg is higher than 20 ° C, the adhesive strength cannot be exhibited at room temperature.

The Tg is not particularly limited, but can be measured in accordance with JIS K7121 by differential scanning calorimetry (DSC), for example, using the pressure-sensitive adhesive layer as a measurement sample. Specifically, for example, as a measuring device, a device name "Q-2000" manufactured by TA instruments can be used, and measurement can be performed from −80 ° C. to 80 ° C. under the condition of a heating rate of 10 ° C./min.

The thickness of the photocurable pressure-sensitive adhesive layer (A) is not particularly limited, and may be appropriately set so that the light emitting elements arranged on the display panel described later can be sufficiently sealed. For example, the thickness of the photocurable pressure-sensitive adhesive layer (A) is 1.0 to 4.0 times, preferably 1.1 to 3.0 times, more preferably 1.2 to 2 times the height of the light emitting element. It is adjusted to be 5.5 times, more preferably 1.3 to 2.0 times. By increasing the thickness to 1.0 times or more, the photocurable pressure-sensitive adhesive layer (A) can easily follow the step, and the step absorption property is improved. Further, by setting the thickness to 4.0 or less, the photocurable pressure-sensitive adhesive layer (A) is less likely to be deformed, and the workability is improved.

The thickness of the photocurable pressure-sensitive adhesive layer (A) is, for example, about 10 to 500 μm, and may be 20 μm or more, 30 μm or more, 40 μm or more, or 50 μm or more. The thickness of the photocurable pressure-sensitive adhesive layer (A) may be 400 μm or less, 300 μm or less, 250 μm or less, or 200 μm or less. By setting the thickness to 10 μm or more, the photocurable pressure-sensitive adhesive layer (A) can easily follow the step portion, and the step absorption property is improved. Further, by setting the thickness to 500 μm or less, the photocurable pressure-sensitive adhesive layer (A) is less likely to be deformed, and the workability is improved.

Since the photocurable pressure-sensitive adhesive layer (A) exhibits excellent light-shielding properties against visible light, even when a metal adherend is laminated on the photo-curable pressure-sensitive adhesive layer (A), reflection on the metal surface and Gloss can be prevented. The reflectance in the visible light region of 5 ° specular reflection when the metal adherend is laminated on the photocurable pressure-sensitive adhesive layer (A) is preferably 50% or less, more preferably 30% or less. It is preferably 15% or less, more preferably 10% or less, and particularly preferably 10% or less. The glossiness (based on JIS Z 8741-1997) when the metal adherend is laminated on the photocurable pressure-sensitive adhesive layer (A) is preferably 100% or less, and more preferably 80% or less. , 60% or less, more preferably 50% or less.
As the metal adherend, copper, aluminum, stainless steel, or the like can be used.

[Formation of photocured product]
The photocurable pressure-sensitive adhesive layer (A) can be photocrosslinked, for example, by irradiating the benzophenone structure with ultraviolet rays containing an excitable wavelength component. It is preferable to use a light source capable of irradiating ultraviolet rays containing a component having a wavelength of less than 300 nm. Examples of such a light source include, but are not limited to, high-pressure mercury lamps, low-pressure mercury lamps, metal halide lamps, super UV lamps, and the like. The light emitted by the light source may contain a component having a wavelength of 300 nm or more.

Examples of the light source that does not contain a wavelength component capable of exciting the benzophenone structure (for example, a component having a wavelength of less than 300 nm) or can irradiate ultraviolet rays having a small wavelength component include a black light and a UV-LED lamp. These light sources can be preferably adopted as a light source for advancing the reaction of ethylenically unsaturated groups (polymerization reaction or curing reaction) by light irradiation performed in the presence of a benzophenone structure. In ultraviolet irradiation for reacting an ethylenically unsaturated group, the above-mentioned photopolymerization initiator (C) can be used to promote the reaction.

The photocurable pressure-sensitive adhesive layer (A) may have a composition substantially free of a photopolymerization initiator that absorbs light having a wavelength of 300 nm or more and generates a radical, and is visible, for example, at 380 nm or more (particularly 400 nm or more). The composition may be substantially free of a photopolymerization initiator that absorbs light and generates radicals. This can be advantageous from the viewpoint of the optical properties of the photocurable pressure-sensitive adhesive layer (A). In addition, the above-mentioned photopolymerization initiator in a form capable of generating the above-mentioned radical (a form having a site to be cleaved by the above-mentioned light) does not contain the photopolymerization initiator that absorbs light having a wavelength of 300 nm or more and generates a radical. It means that it is not contained, and it is acceptable to contain the cleavage residue of the photopolymerization initiator. The photocurable pressure-sensitive adhesive layer (A) according to a preferred embodiment does not substantially contain a photopolymerization initiator containing a phosphorus element in the molecule. The photocurable pressure-sensitive adhesive layer (A) disclosed herein may be substantially free of any of the photopolymerization initiator containing a phosphorus element in the molecule and the cleavage residue of the photopolymerization initiator.

[Photo-curable adhesive sheet (A)]
The photocurable pressure-sensitive adhesive sheet (A) has a photo-curable pressure-sensitive adhesive layer (A).
The form of the photocurable pressure-sensitive adhesive sheet (A) is not particularly limited as long as it has an adhesive surface formed by the surface of the photo-curable pressure-sensitive adhesive layer (A). The photocurable pressure-sensitive adhesive sheet (A) may be a single-sided pressure-sensitive adhesive sheet having only one side as a pressure-sensitive adhesive surface, or may be a double-sided pressure-sensitive adhesive sheet having both sides having adhesive surfaces. When the photocurable pressure-sensitive adhesive sheet (A) is a double-sided pressure-sensitive adhesive sheet, the photo-curable pressure-sensitive adhesive sheet (A) has a form in which both pressure-sensitive adhesive surfaces are provided by the photo-curable pressure-sensitive adhesive layer (A). Alternatively, one adhesive surface is provided by the photocurable adhesive layer (A), and the other adhesive surface is provided by an adhesive layer (other adhesive layer) other than the photocurable adhesive layer (A). It may have a form to be used. From the viewpoint of adhering the adherends to each other, a double-sided pressure-sensitive adhesive sheet is preferable, and more preferably, a double-sided pressure-sensitive adhesive sheet in which both sides of the sheet are the surfaces of the photocurable pressure-sensitive adhesive layer (A).

The photocurable pressure-sensitive adhesive sheet (A) is a pressure-sensitive adhesive sheet having no base material (base material layer), that is, a so-called "base material-less type" pressure-sensitive adhesive sheet (sometimes referred to as "base material-less pressure-sensitive adhesive sheet"). It may be an adhesive sheet having a base material (sometimes referred to as "adhesive sheet with a base material"). The base material-less pressure-sensitive adhesive sheet in the present invention includes, for example, a double-sided pressure-sensitive adhesive sheet composed of only a photo-curable pressure-sensitive adhesive layer (A), and a photo-curable pressure-sensitive adhesive layer (A) and another pressure-sensitive adhesive layer (photo-curable). A double-sided pressure-sensitive adhesive sheet composed of a pressure-sensitive adhesive layer (a pressure-sensitive adhesive layer other than the pressure-sensitive adhesive layer (A)) can be mentioned. As the pressure-sensitive adhesive sheet with a base material in the present invention, for example, a single-sided pressure-sensitive adhesive sheet having a photocurable pressure-sensitive adhesive layer (A) on one side of the base material and a photo-curable pressure-sensitive adhesive layer (A) on both sides of the base material. Examples thereof include a double-sided pressure-sensitive adhesive sheet having a double-sided pressure-sensitive adhesive sheet and a double-sided pressure-sensitive adhesive sheet having a photocurable pressure-sensitive adhesive layer (A) on one surface side of the base material and another pressure-sensitive adhesive layer on the other surface side.

Among the above, from the viewpoint of improving optical properties such as transparency, a base material-less pressure-sensitive adhesive sheet is preferable, and more preferably, a double-sided pressure-sensitive adhesive sheet (base) having only a photocurable pressure-sensitive adhesive layer (A) and having no base material. Material-less double-sided adhesive sheet). Further, when the photocurable pressure-sensitive adhesive sheet (A) is a pressure-sensitive adhesive sheet having a base material, the photo-curable pressure-sensitive adhesive layer (A) is provided on both sides of the base material from the viewpoint of processability. It is preferably a double-sided pressure-sensitive adhesive sheet (double-sided pressure-sensitive adhesive sheet with a base material).
The above-mentioned "base material (base material layer)" means that when the photocurable pressure-sensitive adhesive layer (A) is used (attached) to an adherend (optical member or the like), it is adhered together with the pressure-sensitive adhesive layer. It is a part to be attached to the body and does not include a release film (separator) that is peeled off when the adhesive sheet is used (attached).

As described above, the photocurable adhesive sheet A may be an adhesive sheet with a base material. Examples of such a substrate include various optical films such as a plastic film, an antireflection (AR) film, a polarizing plate, and a retardation plate. Examples of the material such as the plastic film include polyester resins such as polyethylene terephthalate (PET), acrylic resins such as polymethylmethacrylate (PMMA), polycarbonates, triacetylcellulose (TAC), polysulfone, polyallylates, and polyimides. Polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, ethylene-propylene copolymer, trade name "Arton" (cyclic olefin polymer, manufactured by JSR Co., Ltd.), trade name "Zeonoa" (cyclic olefin polymer, Nippon Zeon Co., Ltd.) Examples thereof include plastic materials such as cyclic olefin-based polymers such as "manufactured by the company". In addition, these plastic materials may be used alone or in combination of 2 or more types.

The base material is preferably transparent. The total light transmittance (according to JIS K7361-1) in the visible light wavelength region of the base material is not particularly limited, but is preferably 85% or more, more preferably 88% or more. The haze of the base material (according to JIS K7136) is not particularly limited, but is preferably 1.5% or less, more preferably 1.0% or less. Examples of such a transparent base material include PET films and non-oriented films such as the trade name "Arton" and the trade name "Zeonoa".

The thickness of the base material is not particularly limited, but is preferably 12 to 75 μm. The base material may have either a single layer or a plurality of layers. Further, the surface of the base material is known to have, for example, antireflection treatment (AR treatment), antireflection treatment such as antiglare treatment, physical treatment such as corona discharge treatment and plasma treatment, and chemical treatment such as undercoating treatment. Conventional surface treatments may be appropriately applied.

As described above, the photocurable pressure-sensitive adhesive sheet (A) may have another pressure-sensitive adhesive layer (a pressure-sensitive adhesive layer other than the pressure-sensitive adhesive layer A). The other adhesive layer is not particularly limited, and is, for example, a urethane adhesive, an acrylic adhesive, a rubber adhesive, a silicone adhesive, a polyester adhesive, a polyamide adhesive, and an epoxy adhesive. , A pressure-sensitive adhesive layer formed from a known or commonly used pressure-sensitive adhesive such as a vinyl alkyl ether-based pressure-sensitive adhesive and a fluorine-based pressure-sensitive adhesive. The pressure-sensitive adhesive may be used alone or in combination of two or more.

Further, the photocurable pressure-sensitive adhesive sheet (A) is not limited to the photo-curable pressure-sensitive adhesive layer (A), the base material, and the other pressure-sensitive adhesive layer, but also other layers (for example, other than the photo-curable pressure-sensitive adhesive layer (A), as long as the effects of the present invention are not impaired. It may have an intermediate layer, an undercoat layer, etc.).

The photocurable adhesive sheet (A) may be provided with a release film (separator) on the adhesive surface until use. The form in which the adhesive surface of the photocurable adhesive sheet (A) is protected by the release film is not particularly limited, but the form in which the respective adhesive surfaces are protected by the two release films may be used, or may be in the form of a roll. A single release film having both sides of the release surface by being wound around the film may be in a form in which each adhesive surface is protected. The release film is used as a protective material for the pressure-sensitive adhesive layer and is peeled off when it is attached to an adherend. In the photocurable pressure-sensitive adhesive sheet (A), the release film also serves as a support for the pressure-sensitive adhesive layer. The release film does not necessarily have to be provided.

The thickness (total thickness) of the photocurable pressure-sensitive adhesive sheet (A) is not particularly limited, but is preferably 10 μm to 1 mm, more preferably 100 to 500 μm, and further preferably 150 to 350 μm. By setting the thickness to 10 μm or more, the photocurable pressure-sensitive adhesive layer (A) can easily follow the step portion, and the step absorption can be improved. The thickness of the photocurable pressure-sensitive adhesive sheet (A) does not include the thickness of the release film.

Since the photocurable pressure-sensitive adhesive sheet (A) contains the photo-curable pressure-sensitive adhesive layer (A), it has light absorption with respect to visible light. The total light transmittance of the photocurable adhesive sheet (A) is, for example, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less or. It may be 5% or less.

Since the photocurable pressure-sensitive adhesive sheet (A) has the photo-curable pressure-sensitive adhesive layer (A), it has excellent step absorption before curing. For example, in addition to a step of 5 to 10 μm, it is excellent in step absorption even for a high step exceeding 40 μm. Furthermore, it has step absorption even for high steps exceeding 80 μm.

Further, since the photocurable pressure-sensitive adhesive sheet (A) has a photo-curable pressure-sensitive adhesive layer (A), it has excellent processability after curing, chipping of glue during cutting, and from the end during storage. The sticking out and sagging of the adhesive layer are suppressed.
Further, since the photocurable pressure-sensitive adhesive sheet (A) has the photo-curable pressure-sensitive adhesive layer (A), the adhesive reliability is also excellent.

1 to 3 are views (cross-sectional views) schematically showing an embodiment of the photocurable pressure-sensitive adhesive sheet (A) of the present invention.
An embodiment of the photocurable pressure-sensitive adhesive sheet (A) is shown in FIG. The photocurable pressure-sensitive adhesive sheet 1A has a photo-curable pressure-sensitive adhesive layer 10 in which one surface 10A is a surface (adhesive surface) to be attached to an adherend, and the other surface 10B of the photo-curable pressure-sensitive adhesive layer 10. It is configured as a single-sided adhesive photocurable pressure-sensitive adhesive sheet containing the base material S1 laminated on the above. The photocurable pressure-sensitive adhesive layer 10 is bonded to one surface S1A of the base material S1. As the base material S1, a plastic film such as a polyester film can be used. The base material S1 may be, for example, an optical film such as a polarizing plate or a cover member. In the embodiment shown in FIG. 1, the photocurable pressure-sensitive adhesive layer 10 has a single-layer structure. The pressure-sensitive adhesive sheet 1A before use (before sticking to the adherend) has, for example, as shown in FIG. 1, a peeling film S2 in which the pressure-sensitive adhesive surface 10A has at least the pressure-sensitive adhesive layer side as a peelable surface (peeling surface). It may be in the form of an adhesive sheet 50 with a release film, protected by. Alternatively, the second surface S1B of the base material S1 (the surface opposite to the first surface S1A and also referred to as the back surface) is a peeling surface, and the adhesive surface 10A is on the second surface S1B of the base material S1. The adhesive surface 10A may be protected by being wound or laminated so as to be in contact with each other.

The release film is not particularly limited, and for example, a release film in which the surface of a film base material such as a resin film or paper has been peeled off, a fluoropolymer (polytetrafluoroethylene, etc.), a polyolefin resin (polyethylene, polypropylene, etc.), etc. ), A release film made of a low-adhesion material or the like can be used. For the peeling treatment, for example, a silicone-based or long-chain alkyl-based peeling treatment agent may be used. In some embodiments, the release-treated resin film can be preferably used as the release film.

The photocurable pressure-sensitive adhesive sheet (A) may be in the form of a base-less double-sided pressure-sensitive adhesive sheet composed of the photo-curable pressure-sensitive adhesive layer (A). As shown in FIG. 2, in the base material-less double-sided pressure-sensitive adhesive sheet 1B, before use, each

side surface

10A and 10B of the pressure-sensitive adhesive layer 10 has at least a peelable surface (peeling surface) on the pressure-sensitive adhesive layer side. It may be in the form protected by the films S3 and S4. Alternatively, the back surface of the release film S4 (the surface opposite to the adhesive side) is the release surface, and the adhesive surface is wound or laminated so that the adhesive surface 10B abuts on the back surface of the release film S4. 10A and 10B may be in a protected form. Such a base material-less double-sided pressure-sensitive adhesive sheet can be used, for example, by bonding a base material to the surface of either one of the pressure-sensitive adhesive layers.

The photocurable pressure-sensitive adhesive sheet (A) can be a component of an optical member with a pressure-sensitive adhesive sheet to which an optical member is bonded to one surface of the pressure-sensitive adhesive layer. For example, the photocurable pressure-sensitive adhesive sheet 1A shown in FIG. 1 can be a component of the optical member 100 with a pressure-sensitive adhesive sheet to which the optical member S5 is bonded to one surface 10A of the pressure-sensitive adhesive layer 10, as shown in FIG. .. The optical member may be, for example, a glass plate, a resin film, a metal plate, an LED panel described later, or the like.

The photocurable pressure-sensitive adhesive layer (A) constituting the photo-curable pressure-sensitive adhesive sheet (A) can be a cured layer of the corresponding pressure-sensitive adhesive composition (A). For example, the photocurable pressure-sensitive adhesive layer (A) may be one in which the pressure-sensitive adhesive composition (A) is applied (for example, applied) to an appropriate surface and then the pressure-sensitive adhesive composition (A) is cured. Curing of the pressure-sensitive adhesive composition (A) can be preferably performed by irradiation with active energy rays. As the active energy ray for forming the photocurable pressure-sensitive adhesive layer (A), ultraviolet rays are preferable, and ultraviolet rays containing no component having a wavelength of 300 nm or less or having a small wavelength component are more preferable.

The application of the pressure-sensitive adhesive composition (A) can be carried out using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater. .. In the photocurable pressure-sensitive adhesive sheet (A) having a base material, the pressure-sensitive adhesive composition (A) is directly applied to the base material as a method of providing the photo-curable pressure-sensitive adhesive layer (A) on the base material. A direct method for forming the photocurable pressure-sensitive adhesive layer (A) may be used, or a transfer method for transferring the photo-curable pressure-sensitive adhesive layer (A) formed on the peeling surface to a substrate may be used.

<Self-luminous display device>
In the self-luminous display device according to the fifth aspect of the present invention, a small and large number of light emitting elements are arranged on a wiring substrate, and each light emitting element is selectively emitted by a light emitting control means connected thereto. , A display device capable of displaying visual information such as characters, images, and moving images directly on a display screen by blinking each light emitting element. Examples of the self-luminous display device include a mini / micro LED display device and an organic EL (electroluminescence) display device. The photocurable pressure-sensitive adhesive sheet A according to the first aspect of the present invention is particularly preferably used for manufacturing a mini / micro LED display device.

FIG. 4 is a schematic view (cross-sectional view) showing an embodiment of a self-luminous display device (mini / micro LED display device) on the fifth side surface of the present invention.
In FIG. 4, the mini / micro LED display device 200A includes a display panel in which a plurality of LED chips 23 are arranged via a metal wiring layer 22 on one side of a substrate 21, and a display panel laminated on the display panel to form a metal wiring layer 22. It is composed of a pressure-sensitive adhesive layer 20 for sealing a plurality of LED chips 23 and a cover member 24 laminated on the upper portion (image display side) of the pressure-sensitive adhesive layer 20. The cover member 24 is not particularly limited, but can be made of the same material as the above-mentioned "base material".

In the mini / micro LED display device 200A of the present embodiment, a metal wiring layer 22 for sending a light emission control signal to each LED chip 23 is laminated on the substrate 21 of the display panel. The LED chips 23 that emit light of each color of red (R), green (G), and blue (B) are alternately arranged on the substrate 21 of the display panel via the metal wiring layer 22. The metal wiring layer 22 is made of a metal such as copper, and reflects the light emitted from each LED chip 23 to reduce the visibility of the image. Further, the light emitted from each LED chip 23 of each color of RGB is mixed, and the contrast is lowered.

In the mini / micro LED display device 200A of the present embodiment, each LED chip 23 arranged on the display panel is sealed by the adhesive layer 20. The pressure-sensitive adhesive layer 20 is composed of a cured product of the photocurable pressure-sensitive adhesive layer (A) of the present invention. The pressure-sensitive adhesive layer 20 sufficiently follows the minute steps between the plurality of LED chips 23 and is sealed without gaps.

The pressure-sensitive adhesive layer 20 has sufficient light-shielding properties in the visible light region. Since the fine step between the LED chips 23 is sealed without gaps by the adhesive layer 20 having a high light-shielding property, it is possible to prevent reflection by the metal wiring layer 22 and prevent color mixing between the LED chips 23. And the contrast can be improved.

Further, since the pressure-sensitive adhesive layer 20 is a cured product of the photocurable pressure-sensitive adhesive layer (A), it is excellent in processability. Therefore, the adhesive chipping during the cutting process of the mini / micro LED display device 200A of the present embodiment, and the protrusion and sagging of the adhesive layer 20 from the end portion during storage are suppressed.

The self-luminous display device (mini / micro LED display device) of the present embodiment may include an optical member other than the display panel, the adhesive layer, and the cover member. The optical member is not particularly limited, and examples thereof include a polarizing plate, a retardation plate, an antireflection film, a viewing angle adjusting film, and an optical compensation film. The optical member shall also include a member (design film, decorative film, surface protective plate, etc.) that plays a role of decoration and protection while maintaining the visibility of the display device and the input device.

The self-luminous display device (mini / micro LED display device) of the present embodiment is not particularly limited, but can be preferably manufactured by a method including the following steps.
(1) A photocurable pressure-sensitive adhesive layer (A) of a photo-curable pressure-sensitive adhesive sheet (A) is laminated on a display panel in which a plurality of light-emitting elements are arranged on one side of a substrate, and the light-emitting element is made of a photo-curable pressure-sensitive adhesive. The step of sealing with the layer (A).
(2) A step of irradiating the photocurable pressure-sensitive adhesive layer (A) with ultraviolet rays to cure the photocurable pressure-sensitive adhesive layer (A).

FIG. 5 is a diagram schematically showing a process for carrying out one embodiment of a method for manufacturing a self-luminous display device (mini / micro LED display device) according to the fifth aspect of the present invention. In the present embodiment, as shown in FIG. 5A, a plurality of light emitting elements (1C) on the fourth side surface of the present invention and a plurality of light emitting elements (on one side of the substrate 21) via the metal wiring layer 22. A display panel in which the LED chips) 23 are arranged is used.

In this embodiment, the photocurable pressure-sensitive adhesive sheet 1C is composed of a photo-curable pressure-sensitive adhesive layer 10 and a cover member 24. In this embodiment, the photocurable pressure-sensitive adhesive sheet 1C has a cover member 24, but the cover member 24 may not be present. The cover member 24 is not particularly limited, but may be made of the same material as the above-mentioned "base material", and may be a release film (separator).

Next, as shown in FIG. 5B, the cover member 24 of the photocurable adhesive layer 10 of the photocurable adhesive sheet 1C is not laminated on the surface of the display panel on which the plurality of LED chips are arranged. The surfaces 10A are laminated, and the LED chip 23 and the metal wiring layer 22 are sealed with the photocurable pressure-sensitive adhesive layer 10. The lamination can be carried out by a known method, for example, under heating and pressurizing conditions using an autoclave. The photocurable pressure-sensitive adhesive layer 10 of the photo-curable pressure-sensitive adhesive sheet 1C has high fluidity and exhibits excellent step absorption. Therefore, the photocurable pressure-sensitive adhesive layer 10 is sealed so as to fill the step between the metal wiring layer 22 and the plurality of LED chips 23 without gaps.

Next, as shown in FIG. 5C, the photocurable pressure-sensitive adhesive layer 10 is irradiated with ultraviolet rays to be cured. When the benzophenone structure contained in the photocurable pressure-sensitive adhesive layer 10 is excited by irradiation with ultraviolet rays, a crosslinked structure is formed by utilizing the extraction reaction of hydrogen radicals, and the curing reaction is started. The ultraviolet rays are not particularly limited as long as the photocurable pressure-sensitive adhesive layer 10 is cured by exciting the benzophenone structure, but ultraviolet rays in which the photo-curable pressure-sensitive adhesive layer 10 exhibits transparency are preferable. That is, since the photocurable pressure-sensitive adhesive layer 10 has high light-shielding property against visible light and high transparency to ultraviolet rays, the photo-curable pressure-sensitive adhesive layer 10 can be cured by ultraviolet rays. FIG. 5C is an embodiment in which the photocurable pressure-sensitive adhesive layer 10 is irradiated with ultraviolet rays U to be cured.

The ultraviolet rays are preferably ultraviolet rays having a wavelength of 200 to 400 nm, and more preferably ultraviolet rays having a wavelength of less than 300 nm.

As the light source for irradiating ultraviolet rays, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, a microwave-excited lamp, a metal halide lamp, a chemical lamp, a black light, or an LED can be used. Regarding the irradiation time and irradiation method of ultraviolet rays, the photocurable pressure-sensitive adhesive layer 10 can be cured without unreasonably affecting the display panel, and the photo-curable pressure-sensitive adhesive layer 10 is cured to provide sufficient processability. As long as it is shown, it can be set as appropriate. For example, the irradiation amount (integrated light amount) of ultraviolet rays is preferably 1000 mJ / cm ² to 10000 mJ / cm ² , more preferably 2000 mJ / cm ² to 4000 mJ / cm ² , and further preferably 3000 mJ / cm ² . ..

By curing the photocurable pressure-sensitive adhesive layer 10, a self-luminous display device (mini / micro LED display device) 200B can be obtained as shown in FIG. 5 (d). In FIG. 5D, the pressure-sensitive adhesive layer 20 is a pressure-sensitive adhesive layer obtained by curing the photocurable pressure-sensitive adhesive layer 10. The self-luminous display device (mini / micro LED display device) 200B is an embodiment showing an example of the self-luminous display device (mini / micro LED display device) on the fifth aspect of the present invention.

The adhesive layer 20 has improved workability, and it is possible to prevent adhesive chipping during cutting processing and protrusion and sagging of the adhesive layer from the edges during storage. Further, the pressure-sensitive adhesive layer 20 suppresses the generation of gas such as carbon dioxide due to the heating of the display panel, can prevent the generation of bubbles, and improves the adhesion reliability.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

[Example 1]
(Preparation of adhesive composition)
An acrylic copolymer having a benzophenone structure on the side chain in a separable flask equipped with a thermometer, a stirrer, a reflux cooling tube and a nitrogen gas introduction tube (manufactured by BASF, trade name "acResin A260UV", Tg: -39 ° C. , Mw: 19 × 104, BP equivalent: ² mg / g) 50 parts by weight, butyl acrylate (BA) 26 parts by weight, N-vinyl-2-pyrrolidone (NVP) 8 parts by weight, isobornyl acrylate (IBXA) 16 0.2 parts by weight and 0.2 parts by weight of a photopolymerization initiator (manufactured by IGM Regins, trade name "Omnirad 184") having an absorption peak in the wavelength range of 300 nm to 500 nm are charged and mixed to obtain the pressure-sensitive adhesive composition A. Prepared.

(Preparation of black adhesive composition)
To 100 parts by weight of the pressure-sensitive adhesive composition A, 0.5 part by weight of a 20% dispersion of a black pigment (“9256BLACK” manufactured by Tokushiki) was added to prepare a black pressure-sensitive adhesive composition B1.

(Preparation of photocurable adhesive sheet)
The black pressure-sensitive adhesive composition B1 prepared above is applied to the peeling surface of a release film R1 (MRF # 38, manufactured by Mitsubishi Resin Co., Ltd.) having a thickness of 38 μm in which one side of the polyester film is a peeling surface, and one side of the polyester film is applied. Was covered with a release film R2 (MRE # 38 manufactured by Mitsubishi Resin Co., Ltd.) having a release surface to block air. Ultraviolet rays were irradiated from one side of this laminate using a black light (manufactured by Toshiba Corporation, trade name FL15BL) under the conditions of an illuminance of 5 mW / cm ² and an integrated light amount of 1300 mJ / cm ² . As a result, the photocurable pressure-sensitive adhesive layer C1 having a thickness of about 100 μm, which is a cured product of the black pressure-sensitive adhesive composition B1, is sandwiched between the release films R1 and R2, and the photo-curable pressure-sensitive adhesive sheet D1 is adhered to both sides without a base material. Obtained in the form of a sheet.
The illuminance value of the black light is a measured value by an industrial UV checker (manufactured by Topcon, trade name: UVR-T1, light receiving unit model UD-T36) having a peak sensitivity wavelength of about 350 nm.

[Example 2]
The same as in Example 1 except that 1 part by weight of a 20% dispersion of a black pigment (“9256BLACK” manufactured by Tokushiki) was added to 100 parts by weight of the pressure-sensitive adhesive composition A to prepare a black pressure-sensitive adhesive composition B2. By the method, a photocurable pressure-sensitive adhesive layer C2 having a thickness of about 100 μm, which is a cured product of the black pressure-sensitive adhesive composition B2, is sandwiched between the release films R1 and R2 to obtain a base-less double-sided pressure-sensitive adhesive sheet D2. Obtained in the form of a sheet.

[Example 3]
The same as in Example 1 except that 2 parts by weight of a 20% dispersion of a black pigment (“9256BLACK” manufactured by Tokushiki) was added to 100 parts by weight of the pressure-sensitive adhesive composition A to prepare a black pressure-sensitive adhesive composition B3. By the method, a photocurable pressure-sensitive adhesive layer C3 having a thickness of about 100 μm, which is a cured product of the black pressure-sensitive adhesive composition B3, is sandwiched between the release films R1 and R2 to obtain a base-less double-sided pressure-sensitive adhesive sheet D3. Obtained in the form of a sheet.

[Example 4]
The same as in Example 1 except that 4 parts by weight of a 20% dispersion of a black pigment (“9256BLACK” manufactured by Tokushiki) was added to 100 parts by weight of the pressure-sensitive adhesive composition A to prepare a black pressure-sensitive adhesive composition B4. By the method, a photocurable pressure-sensitive adhesive layer C4 having a thickness of about 100 μm, which is a cured product of the black pressure-sensitive adhesive composition B4, is sandwiched between the release films R1 and R2 to obtain a base-less double-sided pressure-sensitive adhesive sheet D4. Obtained in the form of a sheet.

[Comparative Example 1]
A photocurable pressure-sensitive adhesive having a thickness of about 100 μm, which is a cured product of the pressure-sensitive adhesive composition A, by the same method as in Example 1 except that a black pigment was not added to 100 parts by weight of the pressure-sensitive adhesive composition A. A photocurable pressure-sensitive adhesive sheet D5 in which the agent layer C5 was sandwiched between the release films R1 and R2 was obtained in the form of a substrate-less double-sided pressure-sensitive adhesive sheet.

[Comparative Example 2]
(Preparation of prepolymer)
In a separable flask equipped with a thermometer, a stirrer, a reflux cooling tube and a nitrogen gas introduction tube, 67 parts by weight of butyl acrylate (BA), 14 parts by weight of cyclohexyl acrylate (CHA) and 4-hydroxybutyl acrylate (4) were added as monomer components. -HBA) 19 parts by weight, photopolymerization initiator (BASF, trade name "Irgacure 184") 0.09 parts by weight, and photopolymerization initiator (BASF, trade name "Irgacure 651") 0.09 weight After charging the parts, nitrogen gas was flowed and nitrogen substitution was performed for about 1 hour while stirring. Then, UVA was irradiated at 5 mW / cm ² to carry out polymerization, and the reaction rate was adjusted to 5 to 15% to obtain an acrylic prepolymer solution.

(Preparation of adhesive composition)
In the acrylic prepolymer solution obtained above (the total amount of the prepolymer is 100 parts by weight), 9 parts by weight of 2-hydroxyethyl acrylate (HEA), 8 parts by weight of 4-hydroxybutyl acrylate (4-HBA), and many. 0.02 parts by weight of dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Kogyo Kagaku, trade name "KAYARAD DPHA") as a functional monomer, and 0.35 parts by weight of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent, and 0.45 parts by weight of a polymerization initiator (BASF "Irgacure 651") was added to obtain a pressure-sensitive adhesive composition.

(Preparation of black adhesive composition)
To 100 parts by weight of the pressure-sensitive adhesive composition, 5.8 parts by weight of a 20% dispersion of black pigment (“9256BLACK” manufactured by Tokushiki) and 0.2 parts by weight of an additional photopolymerization initiator (“Irgacure 651” manufactured by BASF). Addition gave a black pressure-sensitive adhesive composition.

(Making an adhesive sheet)
The black pressure-sensitive adhesive composition prepared above is applied to the peeling surface of a release film R1 (MRF # 38, manufactured by Mitsubishi Resin Co., Ltd.) having a thickness of 38 μm in which one side of the polyester film is a peeling surface, and one side of the polyester film is formed. The peeling film R2 (MRE # 38 manufactured by Mitsubishi Resin Co., Ltd.), which is the peeling surface, was covered to shut off the air. Ultraviolet rays were irradiated from one side of this laminate using a black light (manufactured by Toshiba Corporation, trade name FL15BL) under the conditions of an illuminance of 5 mW / cm ² and an integrated light amount of 1300 mJ / cm ² . As a result, a pressure-sensitive adhesive sheet having a thickness of about 50 μm, which is a cured product of the black pressure-sensitive adhesive composition, sandwiched between the release films R1 and R2 was obtained in the form of a base-less double-sided pressure-sensitive adhesive sheet.

[Example 5]
(Preparation of black adhesive composition)
In 100 parts by weight of the pressure-sensitive adhesive composition prepared in Comparative Example 2, 4 parts by weight of a 20% dispersion of black pigment (“9256BLACK” manufactured by Tokushiki) and an additional photopolymerization initiator (“Irgacure 651” manufactured by BASF) 0. 2 parts by weight and 1 part of 4-acryloyloxybenzophenone manufactured by Ark Polymer were added to obtain a black pressure-sensitive adhesive composition.

(Preparation of photocurable adhesive sheet)
The black pressure-sensitive adhesive composition prepared above is applied to the peeling surface of a release film R1 (MRF # 38, manufactured by Mitsubishi Resin Co., Ltd.) having a thickness of 38 μm in which one side of the polyester film is a peeling surface, and one side of the polyester film is formed. The peeling film R2 (MRE # 38 manufactured by Mitsubishi Resin Co., Ltd.), which is the peeling surface, was covered to shut off the air. Ultraviolet rays were irradiated from one side of this laminate using a black light (manufactured by Toshiba Corporation, trade name FL15BL) under the conditions of an illuminance of 5 mW / cm ² and an integrated light amount of 1300 mJ / cm ² . As a result, a pressure-sensitive adhesive sheet having a thickness of about 100 μm, which is a cured product of the black pressure-sensitive adhesive composition, sandwiched between the release films R1 and R2 was obtained in the form of a base-less double-sided pressure-sensitive adhesive sheet.
The illuminance value of the black light is a measured value by an industrial UV checker (manufactured by Topcon, trade name: UVR-T1, light receiving unit model UD-T36) having a peak sensitivity wavelength of about 350 nm.

[Example 6]
A photocurable pressure-sensitive adhesive sheet was prepared in the same manner as in Example 5 except that 4-acryloyloxybenzophenone was added to two parts.

(evaluation)
The following evaluations were performed using the adhesive sheets obtained in the above Examples and Comparative Examples. The evaluation method is shown below. The results are shown in Table 1.

[Evaluation of transmittance]
The release film on one side was peeled off from the adhesive sheet, and non-alkali glass was attached to the exposed surface. Then, the release film on the other surface was peeled off from the pressure-sensitive adhesive sheet to obtain a sample in which the pressure-sensitive adhesive sheet was bonded on a non-alkali glass plate.
The total light transmittance was measured using a haze meter (manufactured by Murakami Color Science Laboratory Co., Ltd., trade name "HN-150") by the method specified by JIS K7361.

[Evaluation of storage elastic modulus]
Evaluation was performed using ARES GII manufactured by TA Instruments.
An adhesive sheet laminated to a thickness of about 1 mm was sandwiched between 8 mm parallel plates, and measured at an initial strain of 1%, a frequency of 1 Hz, and a heating rate of 5 ° C./min from -50 ° C to 100 ° C. The storage elastic modulus G'at 25 ° C. and 85 ° C. was read and used as the storage elastic modulus G'(G'b10, G'b25, G'b85) before curing.
Regarding the storage elastic modulus G'after curing, a high-pressure mercury lamp irradiated with a high-pressure mercury lamp so as to have an integrated light amount of 3000 mJ / cm ² is laminated on an adhesive sheet sandwiched between release films so as to have a thickness of about 1 mm. Then, it was evaluated in the same manner as above, and the storage elastic modulus after curing was G'(G'a10, G'a25, G'a85).
This integrated light quantity is a measured value by an industrial UV checker (manufactured by Topcon, trade name: UVR-T1, light receiving unit model UD-T36) having a peak sensitivity wavelength of about 350 nm.
Since the pressure-sensitive adhesive sheet of Comparative Example 2 does not show photocurability, the storage elastic modulus G'after curing has not been evaluated.

[Evaluation of step followability]
(Making uneven adherend)
After laminating a laminate of TAC film (thickness 60 μm) and adhesive (thickness 20 μm) on a glass plate of 45 mm × 50 mm, a CO ₂ laser (wavelength 10.6 μm, laser diameter 〇 μm) is used to central 10 mm ×. By performing linear etching processing within a range of 10 mm at a pitch of 150 μm in the vertical direction and a pitch of 225 μm in the horizontal direction, an adherend A in which the TAC film and the pressure-sensitive adhesive layer were processed into a grid-like uneven shape was obtained.
The adherend A imitates an LED panel in which a plurality of LED films are arranged on a substrate.
(Making an adhesive sheet)
The pressure-sensitive adhesive sheets produced in Examples 1 to 4 and Comparative Example 1 were stacked to have a thickness of about 200 μm, and the pressure-sensitive adhesive sheets produced in Comparative Example 2 were stacked to have a thickness of about 250 μm. The release film on one surface of these laminated pressure-sensitive adhesive sheets was peeled off, and a PET film having a thickness of 75 μm was attached to the exposed surface.
(Vacuum bonding)
The adhesive surface exposed by peeling off the other release film of the laminated adhesive sheet obtained above and the processed surface of the adherend A are adhered using a vacuum bonding device (SE340aaH manufactured by CRIMB Products). The processing range of the body A was bonded with an accuracy that allows the pressure-sensitive adhesive sheet to be completely covered, and an evaluation sample consisting of a PET film, a laminated pressure-sensitive adhesive sheet, and an adherend A was obtained. Further, they were brought into close contact by autoclaving (60 minutes under the conditions of 50 ° C. and 0.5 MPa).
(Evaluation of step followability)
In the above evaluation sample, when the adhesive sheet can follow the uneven pattern portion, the processed portion of the adherend A is visually recognized transparently, and the portion that cannot be followed is visually recognized as white. The area of the white part was calculated by shooting with a fixed point camera to evaluate the step followability.

Step followability (%) = 100- {[Area of white part at the time of evaluation] / [Area of white part before bonding = 1 cm ² ] × 100}

[Evaluation of workability]
(Manufacturing of laminated products for workability evaluation)
The release film of the laminated adhesive sheet produced in the section of evaluation of step followability was peeled off and bonded to a fr-4 substrate (thickness 1.2 mm) manufactured by Misumi Corporation. After autoclaving (15 minutes under the conditions of 50 ° C. and 0.5 MPa), the photocurable Examples 1 to 4 and Comparative Example 1 were irradiated with ultraviolet rays. The ultraviolet irradiation conditions were a high-pressure mercury lamp and an integrated light intensity of 3000 mJ / cm ² . The integrated light quantity is a value measured by an industrial UV checker (manufactured by Topcon, trade name: UVR-T1, light receiving unit model UD-T36) having a peak sensitivity wavelength of about 350 nm.
(processing)
Using DTF6450 manufactured by Disco Corporation, the laminate for evaluation of processability obtained above was cut. The cutting conditions were blade type P1A861 (abrasive grain # 400 count), spindle 30 kHz, speed 30 mm / s, and cooling water 1 L / min.
(Evaluation of workability)
The cut end portion was observed from the laminated adhesive sheet side with a stereomicroscope, and the processability was evaluated by the amount of glue squeezed out from the cut end portion. The evaluation criteria are as follows.
◯: 0 to 150 μm
Δ: 150 to 200 μm
×: 200 μm or more

[Evaluation of reflectance]
An aluminum foil was attached to a black acrylic plate to prepare a laminated plate. The release film on one surface of the pressure-sensitive adhesive sheets produced in Examples 1 to 4 and Comparative Examples 1 and 2 was peeled off, and a PET film having a thickness of 75 μm was attached to the exposed surface. The adhesive surface exposed by peeling off the other release film was laminated on the aluminum foil side of the plate to prepare a sample. The obtained sample was placed on a spectrophotometer U4100 (manufactured by Hitachi High-Technology Co., Ltd.) with a PET film on the light source side, and the reflectance (%) in the visible light region of 5 ° specular reflection was measured.

Examples 1 to 6, which are photocurable adhesive sheets, show excellent step followability (step absorption) and workability, and have suppressed transmittance and reflectance, and were used as a sealing material for LED panels. In some cases, excellent antireflection effect and improvement of contrast can be expected. On the other hand, Comparative Example 1, which is a photocurable adhesive sheet but does not contain a colorant, exhibits excellent step followability (step absorption) and workability, but has high transmittance and reflectance, and seals the ED panel. When used as a stop material, the antireflection effect and the improvement of contrast could not be expected. Comparative Example 2, which is an adhesive sheet containing a colorant but not showing photocurability, showed excellent step followability (step absorption), but was inferior in processability.

Variations of the present invention are described below.
[Appendix 1] A colorant and a polymer (A) having a benzophenone structure in the side chain are contained.
A pressure-sensitive adhesive composition in which the maximum value of the transmittance at a wavelength of 200 to 400 nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm.
[Appendix 2] A partial polymer of a colorant and a mixture of monomer components constituting the polymer (A) having a benzophenone structure in the side chain or a mixture of monomer components constituting the polymer (A) having a benzophenone structure in the side chain. Contains,
A pressure-sensitive adhesive composition in which the maximum value of the transmittance at a wavelength of 200 to 400 nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm.
[Appendix 3] The pressure-sensitive adhesive composition according to Appendix 1 or 2, wherein the colorant is a colorant in which the maximum value of the transmittance at a wavelength of 200 to 400 nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm. ..
[Appendix 4] The pressure-sensitive adhesive composition according to any one of Supplementary note 1 to 3, further comprising an ethylenically unsaturated compound (B).
[Appendix 5] The pressure-sensitive adhesive composition according to any one of Supplementary note 1 to 4, further comprising a photopolymerization initiator (C) that absorbs ultraviolet rays having a wavelength of 300 nm to 500 nm to generate radicals.
[Appendix 6] A pressure-sensitive adhesive layer formed by a cured product of the pressure-sensitive adhesive composition according to any one of Supplementary note 1 to 5.
A photocurable pressure-sensitive adhesive layer, wherein the cured product is a cured product in which the benzophenone structure of the polymer (A) having the benzophenone structure in the side chain remains.
[Appendix 7] The photocurable pressure-sensitive adhesive layer according to Appendix 6, wherein the maximum value of the transmittance at a wavelength of 200 to 400 nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm.
[Appendix 8] The photocurable pressure-sensitive adhesive layer according to Supplementary note 6 or 7, wherein the photocurable pressure-sensitive adhesive layer before curing has a storage elastic modulus (G'b85) of less than 65 kPa at 85 ° C.
[Appendix 9] The storage elastic modulus (G'a10) of the photocurable pressure-sensitive adhesive layer after curing at 10 ° C. and the storage elastic modulus (G'b85) of the photo-curable pressure-sensitive adhesive layer before curing at 85 ° C. The photocurable pressure-sensitive adhesive layer according to any one of Supplementary note 6 to 8, which satisfies the following relational expression (1).
2.8 <G'a10 / G'b85 (1)
[Appendix 10] The photocurable pressure-sensitive adhesive according to any one of Supplementary note 6 to 9, wherein the photocurable pressure-sensitive adhesive layer after curing has a storage elastic modulus (G'a10) of 90 kPa or more at 10 ° C. layer.
[Appendix 11] The photocurable pressure-sensitive adhesive layer according to any one of Supplementary note 6 to 10, wherein the curing is performed by irradiation with ultraviolet rays having a wavelength of less than 300 nm and an integrated light amount of 3000 mJ / cm ² .
[Appendix 12] A photocurable pressure-sensitive adhesive sheet having the photo-curable pressure-sensitive adhesive layer according to any one of Supplementary note 6 to 11.
[Appendix 13] A display panel in which a plurality of light emitting elements are arranged on one side of a substrate, and
A self-luminous display device comprising the photocurable adhesive sheet according to Appendix 12.
The light emitting element of the display panel is sealed with the photocurable pressure-sensitive adhesive layer of the photo-curable pressure-sensitive adhesive sheet.
A self-luminous display device in which the photocurable pressure-sensitive adhesive layer is cured.
[Appendix 14] The self-luminous display device according to Annex 13, wherein the display panel is an LED panel in which a plurality of LED chips are arranged on one side of a substrate.
[Appendix 15] A photocurable pressure-sensitive adhesive layer of the photocurable pressure-sensitive adhesive sheet according to Appendix 12 is laminated on a display panel in which a plurality of light-emitting elements are arranged on one side of a substrate, and the light-emitting element is coated with a photocurable pressure-sensitive adhesive. The method for manufacturing a self-luminous display device according to Appendix 13 or 14, comprising a step of sealing with a layer and a step of irradiating the photocurable pressure-sensitive adhesive layer with ultraviolet rays to cure the light-curable pressure-sensitive adhesive layer.
[Appendix 16] The manufacturing method according to Annex 15, wherein the ultraviolet rays are ultraviolet rays having a wavelength of less than 300 nm.

The photocurable adhesive sheet of the present invention is suitable for encapsulating a light emitting element of a self-luminous display device such as a mini / micro LED.

1A-1C Photocurable Adhesive Sheet 10 Photocurable Adhesive Layer 10A One surface (adhesive surface)
10B Another surface S1 Base material S1A First surface S1B Second surface (back surface)
S2 to S4 Peeling film S5 Optical member 50 Adhesive sheet with peeling film 100 Member with

adhesive sheet

200A, 200B Self-luminous display device (mini / micro LED display device)
20 Adhesive layer (after curing)
21 Board 22 Metal wiring layer 23 Light emitting element (LED chip)
24 Cover member

Claims

Contains a colorant and a polymer (A) having a benzophenone structure in the side chain,
A pressure-sensitive adhesive composition in which the maximum value of the transmittance at a wavelength of 200 to 400 nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm.
It contains a colorant and a partial polymer of a mixture of monomer components constituting the polymer (A) having a benzophenone structure in the side chain or a mixture of monomer components constituting the polymer (A) having a benzophenone structure in the side chain.
A pressure-sensitive adhesive composition in which the maximum value of the transmittance at a wavelength of 200 to 400 nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm.
The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the colorant is a colorant in which the maximum value of the transmittance at a wavelength of 200 to 400 nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm.
The pressure-sensitive adhesive composition according to any one of claims 1 to 3, further containing an ethylenically unsaturated compound (B).
The pressure-sensitive adhesive composition according to any one of claims 1 to 4, further comprising a photopolymerization initiator (C) that absorbs ultraviolet rays having a wavelength of 300 nm to 500 nm to generate radicals.
A pressure-sensitive adhesive layer formed by a cured product of the pressure-sensitive adhesive composition according to any one of claims 1 to 5.
A photocurable pressure-sensitive adhesive layer, wherein the cured product is a cured product in which the benzophenone structure of the polymer (A) having the benzophenone structure in the side chain remains.
The photocurable pressure-sensitive adhesive layer according to claim 6, wherein the maximum value of the transmittance at a wavelength of 200 to 400 nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm.
The photocurable pressure-sensitive adhesive layer according to claim 6 or 7, wherein the photocurable pressure-sensitive adhesive layer before curing has a storage elastic modulus (G'b85) of less than 65 kPa at 85 ° C.
The relationship between the storage elastic modulus (G'a10) of the photocurable pressure-sensitive adhesive layer after curing at 10 ° C. and the storage elastic modulus (G'b85) of the photo-curable pressure-sensitive adhesive layer before curing at 85 ° C. is as follows. The photocurable pressure-sensitive adhesive layer according to any one of claims 6 to 8, which satisfies (1).
2.8 <G'a10 / G'b85 (1)
The photocurable pressure-sensitive adhesive layer according to any one of claims 6 to 9, wherein the photo-curable pressure-sensitive adhesive layer after curing has a storage elastic modulus (G'a10) at 10 ° C. of 90 kPa or more.
The photocurable pressure-sensitive adhesive layer according to any one of claims 6 to 10, wherein the curing is performed by irradiation with ultraviolet rays having a wavelength of less than 300 nm and an integrated light amount of 3000 mJ / cm 2 .
A photocurable pressure-sensitive adhesive sheet having the photo-curable pressure-sensitive adhesive layer according to any one of claims 6 to 11.
A display panel with multiple light emitting elements arranged on one side of the board,
A self-luminous display device comprising the photocurable adhesive sheet according to claim 12.
The light emitting element of the display panel is sealed with the photocurable pressure-sensitive adhesive layer of the photo-curable pressure-sensitive adhesive sheet.
A self-luminous display device in which the photocurable pressure-sensitive adhesive layer is cured.
The self-luminous display device according to claim 13, wherein the display panel is an LED panel in which a plurality of LED chips are arranged on one side of a substrate.
The photocurable pressure-sensitive adhesive layer of the photo-curable pressure-sensitive adhesive sheet according to claim 12 is laminated on a display panel in which a plurality of light-emitting elements are arranged on one side of a substrate, and the light-emitting element is sealed with the photo-curable pressure-sensitive adhesive layer. The method for manufacturing a self-luminous display device according to claim 13, which comprises a step of stopping and a step of irradiating the photocurable pressure-sensitive adhesive layer with ultraviolet rays to cure the photo-curable pressure-sensitive adhesive layer.
The manufacturing method according to claim 15, wherein the ultraviolet rays are ultraviolet rays having a wavelength of less than 300 nm.