CN115989143A - Adhesive composition, photocurable adhesive layer, and photocurable adhesive sheet - Google Patents

Adhesive composition, photocurable adhesive layer, and photocurable adhesive sheet Download PDF

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Publication number
CN115989143A
CN115989143A CN202180053034.5A CN202180053034A CN115989143A CN 115989143 A CN115989143 A CN 115989143A CN 202180053034 A CN202180053034 A CN 202180053034A CN 115989143 A CN115989143 A CN 115989143A
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China
Prior art keywords
adhesive layer
photocurable adhesive
less
photocurable
polymer
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CN202180053034.5A
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Chinese (zh)
Inventor
浅井量子
仲野武史
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Nitto Denko Corp
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Nitto Denko Corp
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Priority claimed from JP2021080520A external-priority patent/JP2022039946A/en
Application filed by Nitto Denko Corp filed Critical Nitto Denko Corp
Publication of CN115989143A publication Critical patent/CN115989143A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/02—Non-macromolecular additives
    • C09J11/04—Non-macromolecular additives inorganic
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
    • C09J11/02—Non-macromolecular additives
    • C09J11/06—Non-macromolecular additives organic
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J151/00—Adhesives based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers
    • C09J151/06—Adhesives based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Adhesives based on derivatives of such polymers grafted on to homopolymers or copolymers of aliphatic hydrocarbons containing only one carbon-to-carbon double bond
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J201/00—Adhesives based on unspecified macromolecular compounds
    • C09J201/02—Adhesives based on unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups
    • C09J201/06—Adhesives based on unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups containing oxygen atoms
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J4/00—Adhesives based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; adhesives, based on monomers of macromolecular compounds of groups C09J183/00 - C09J183/16
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J4/00—Adhesives based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond ; adhesives, based on monomers of macromolecular compounds of groups C09J183/00 - C09J183/16
    • C09J4/06—Organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond in combination with a macromolecular compound other than an unsaturated polymer of groups C09J159/00 - C09J187/00
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/30—Adhesives in the form of films or foils characterised by the adhesive composition
    • C09J7/38—Pressure-sensitive adhesives [PSA]
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/22—Absorbing filters
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/52—Encapsulations
    • H01L33/56—Materials, e.g. epoxy or silicone resin

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Manufacturing & Machinery (AREA)
  • Power Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Optics & Photonics (AREA)
  • Theoretical Computer Science (AREA)
  • Adhesives Or Adhesive Processes (AREA)

Abstract

The purpose of the present invention is to provide an adhesive composition, an adhesive layer, and an adhesive sheet that are suitable for manufacturing a self-light-emitting display device such as a mini/micro LED display device having an improved contrast and a function of preventing reflection of metal wiring or the like, and that have both excellent level difference absorption properties and excellent processability. The present invention provides: an adhesive composition which comprises a colorant and a partial polymer of a polymer (A) having a benzophenone structure in a side chain, or a mixture of monomer components constituting the polymer (A) having a benzophenone structure in a side chain, and which has a maximum value of transmittance at a wavelength of 200 to 400nm which is larger than a maximum value of transmittance at a wavelength of 400 to 700 nm; a photocurable adhesive layer formed from a cured product of the adhesive composition, wherein the cured product is a cured product in which a benzophenone structure possessed by the polymer (a) having a benzophenone structure in a side chain remains; a photocurable adhesive sheet has the photocurable adhesive layer.

Description

Adhesive composition, photocurable adhesive layer, and photocurable adhesive sheet
Technical Field
The invention relates to an adhesive composition, a photocurable adhesive layer and a photocurable adhesive sheet. More specifically, the present invention relates to an adhesive composition, a photocurable adhesive layer, and a photocurable adhesive sheet suitable for sealing a light-emitting element of a self-luminous display device such as a mini-or micro-LED.
Background
In recent years, as a next-generation Display device, a self-Light-Emitting Display device represented by a Mini/Micro Light Emitting Diode Display (Mini/Micro Light Emitting Diode Display) has been designed. As a basic configuration of a mini/micro LED display device, a substrate on which a large number of micro LED light emitting elements (LED chips) are arranged at high density is used as a display panel, the LED chips are sealed with a sealing material, and a covering member such as a resin film or a glass plate is laminated on an outermost layer.
Some self-luminous display devices such as mini/micro LED display devices include white backlight systems, white light emitting color filter systems, and RGB systems, and in the white light emitting color filter systems and the RGB systems, a black colored adhesive is used as a sealing material (see, for example, patent documents 1 to 3).
This is because the black adhesive fills in the gaps between the RGB LED chips arranged on the substrate of the display panel, thereby contributing to prevention of color mixing and improvement of contrast, and also can prevent reflection of metal wiring, metal oxide such as ITO, and the like arranged on the substrate of the display panel.
In a mini/micro LED display device, LED chips are densely packed on a substrate, and a large number of minute height differences exist between the LED chips, and a sealing material used for the mini/micro LED display device is required to have a performance of filling the height differences, that is, an excellent height difference absorbing property (also referred to as "height difference following property"). Therefore, in order to improve the level difference absorption property, the black adhesive needs to be designed to exhibit high fluidity.
On the other hand, a pressure-sensitive adhesive exhibiting high fluidity has a problem of poor processability such as shape stability and handling properties, although it is excellent in level difference absorption. For example, a laminate having a pressure-sensitive adhesive layer exhibiting high fluidity is likely to suffer from problems such as glue shortage during cutting, overflow and sagging of the pressure-sensitive adhesive layer from the edge during storage, and process contamination due to adhesion of foreign matter to the overflowing pressure-sensitive adhesive layer.
As an adhesive that achieves both the level difference absorption property and the processability, a photocurable adhesive (a mixed adhesive) is known (see, for example, patent document 4). For the hybrid binder, the following advantages are obtained: first, the fluidity is high, and the cured product is made into a semi-cured state with excellent level difference absorbability to sufficiently follow the level difference, and then, the curing is finished by irradiating light, so that the processability can be improved.
Documents of the prior art
Patent literature
Patent document 1: japanese patent laid-open publication No. 2019-204905
Patent document 2: japanese laid-open patent publication No. 2017-203810
Patent document 3: JP 2018-523854A
Patent document 4: international publication WO2016/170875
Disclosure of Invention
Problems to be solved by the invention
However, when the mixed binder is colored black by adding carbon black or the like, for example, light cannot transmit through the binder, and therefore, there is a problem that curing is suppressed and it is difficult to improve processability.
The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide an adhesive composition, an adhesive layer, and an adhesive sheet which are suitable for manufacturing a self-luminous display device such as a mini/micro LED display device having an improved function of preventing reflection of metal wiring and the like and an improved contrast, and which have both excellent level difference absorption and excellent processability.
Means for solving the problems
As a result of intensive studies to achieve the above object, the present inventors have found that an adhesive composition, a photocurable adhesive layer, and a photocurable adhesive sheet are colored so as to exhibit absorption in the visible region but have high transmittance in the ultraviolet region, thereby exhibiting high light-shielding properties against visible light and being curable by ultraviolet irradiation. Further, it has been found that by using a partial polymer containing a polymer having a benzophenone structure in a side chain, a mixture of monomer components constituting the polymer, or a mixture of monomer components constituting the polymer as the adhesive composition, a photocurable adhesive layer and a photocurable adhesive sheet which can achieve both of excellent level difference absorption before photocuring and excellent processability after photocuring can be provided, and a function of preventing reflection of metal wiring and the like in a self-luminous display device, an improvement in contrast, and both of excellent level difference absorption and processability can be achieved. The present invention has been completed based on these findings.
The 1 st aspect of the present invention provides an adhesive composition containing a colorant and a polymer (a) having a benzophenone structure in a side chain, the adhesive composition having a maximum value of transmittance at a wavelength of 200 to 400nm which is larger than a maximum value of transmittance at a wavelength of 400 to 700 nm.
The 2 nd aspect of the present invention provides an adhesive composition containing a colorant and a partial polymer of a mixture of monomer components constituting the polymer (a) having a benzophenone structure in a side chain or a mixture of monomer components constituting the polymer (a) having a benzophenone structure in a side chain, wherein the adhesive composition has a maximum value of transmittance at a wavelength of 200 to 400nm which is larger than a maximum value of transmittance at a wavelength of 400 to 700 nm. The adhesive compositions according to the 1 st and 2 nd aspects of the present invention may further contain an ethylenically unsaturated compound (B).
In the present specification, the pressure-sensitive adhesive compositions according to the 1 st and 2 nd aspects of the present invention may be collectively referred to as "pressure-sensitive adhesive composition (A)".
In the present specification, the term "polymer (a) having a benzophenone structure in a side chain" or "BP polymer (a)" includes "polymer (a) having a benzophenone structure in a side chain" and "partial polymer of a mixture of monomer components constituting polymer (a) having a benzophenone structure in a side chain or a mixture of monomer components constituting polymer (a) having a benzophenone structure in a side chain" unless otherwise specified.
The 3 rd aspect of the present invention provides a photocurable adhesive layer comprising a cured product of an adhesive composition (a), wherein the cured product is a cured product having the benzophenone structure remaining therein. The 4 th aspect of the present invention provides a photocurable adhesive sheet including the photocurable adhesive layer according to the 3 rd aspect of the present invention.
In the present specification, the photocurable adhesive layer on the 3 rd side of the present invention may be referred to as a "photocurable adhesive layer (a)". The photocurable adhesive sheet according to aspect 4 of the present invention may be referred to as a "photocurable adhesive sheet (a)".
The photocurable adhesive layer (a) is formed from a cured product of the adhesive composition (a) that leaves the benzophenone structure of the BP polymer (a) as a residue. The benzophenone structure can be cured by ultraviolet irradiation to form a crosslinked structure. The photocurable adhesive layer (a) before curing is in a semi-cured state with high fluidity, and exhibits excellent level difference absorption. Therefore, when the photocurable adhesive layer (a) before curing is bonded to a display panel in which light-emitting elements (LED chips) are arranged at a high density, the photocurable adhesive layer (a) sufficiently follows the fine height difference between the light-emitting elements (LED chips), and adheres to the display panel without leaving air bubbles and without leaving gaps. On the other hand, the photocurable adhesive layer (a) after curing exhibits excellent processability. Therefore, when the laminate including the cured photocurable adhesive layer (a) is cut, the occurrence of glue shortage can be suppressed, and the occurrence of protrusion and sagging of the adhesive layer from the end can be suppressed during storage. In this way, the photocurable adhesive layer (a) composed of the cured product of the adhesive composition (a) can suitably achieve both excellent level difference absorption properties and processability.
The maximum value of the transmittance at a wavelength of 200 to 400nm of the pressure-sensitive adhesive composition (A) is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm. The maximum value of the transmittance at a wavelength of 200 to 400nm of the photocurable adhesive layer (a) is preferably larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm. That is, the adhesive composition (a) and the photocurable adhesive layer (a) have high absorption of visible light (wavelength of 400 to 700 nm) and excellent light-shielding properties. The adhesive composition (a) and the photocurable adhesive layer (a) are preferable in that they have excellent light-shielding properties against visible light in terms of: the photocurable adhesive layer (a) filled in the fine height difference between the LED chips without a gap 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 adhesive composition (a) and the photocurable adhesive layer (a) have high transparency to ultraviolet rays (wavelength of 200 to 400 nm). The adhesive composition (a) and the photocurable adhesive layer (a) are preferably excellent in the ultraviolet light transmittance, because the photocurable adhesive layer (a) is irradiated with ultraviolet light to cause a curing reaction, thereby improving the workability of the photocurable adhesive layer (a). That is, the configuration in which the maximum value of the transmittance at a wavelength of 200 to 400nm of the adhesive composition (a) and the photocurable adhesive layer (a) is larger than the maximum value of the transmittance at a wavelength of 400 to 700nm is preferable from the viewpoint of being able to achieve both of the excellent light-shielding property against visible light and the curing reaction by ultraviolet irradiation.
The colorant is preferably a colorant having a maximum value of transmittance at a wavelength of 200 to 400nm which is larger than a maximum value of transmittance at a wavelength of 400 to 700 nm. This configuration is preferable in that the maximum value of the transmittance at a wavelength of 200 to 400nm is larger than the maximum value of the transmittance at a wavelength of 400 to 700nm in the pressure-sensitive adhesive composition (a) and the photocurable pressure-sensitive adhesive layer (a).
In the present specification, the "colorant having a maximum value of transmittance at a wavelength of 200 to 400nm larger than a maximum value of transmittance at a wavelength of 400 to 700 nm" may be referred to as "colorant (a)".
The adhesive composition (A) preferably further contains a photopolymerization initiator (C) which absorbs ultraviolet light having a wavelength of 300nm to 500nm and generates radicals. This configuration is preferable for obtaining the photocurable adhesive layer (a) by curing the adhesive composition (a) into a cured product in which the benzophenone structure of the BP polymer (a) remains.
The storage modulus (G' b 85) at 85 ℃ of the photocurable adhesive layer (a) before curing is preferably less than 65kPa. This configuration is preferable for the photocurable adhesive layer (a) before curing to exhibit excellent level difference absorption.
The storage modulus at 10 ℃ (G 'a 10) of the photocurable adhesive layer (a) after curing and the storage modulus at 85 ℃ (G' b 85) of the photocurable adhesive layer (a) before curing preferably satisfy the following relational expression (1).
2.8<G'a10/G'b85 (1)
This configuration is preferable in that the photocurable adhesive layer (a) before curing exhibits excellent level difference absorption and the photocurable adhesive layer (a) after curing exhibits excellent processability.
The storage modulus (G' a 10) of the photocurable adhesive layer (a) after curing at 10 ℃ is preferably 90kPa or more. This configuration is preferable in that the photocurable adhesive layer (a) after curing exhibits excellent processability.
The curing is preferably carried out at a wavelength of less than 300nm and a cumulative light quantity of 3000mJ/cm 2 Curing by ultraviolet irradiation. This structure is preferable in that the photocurable adhesive layer (a) is cured by forming a crosslinked structure in the benzophenone structure by the irradiation of the ultraviolet ray, and exhibits excellent processability.
In addition, the 5 th aspect of the present invention provides a self-luminous display device, comprising: a display panel in which a plurality of light-emitting elements are arranged on one surface of a substrate, and the photocurable adhesive sheet (a), wherein the light-emitting elements of the display panel are sealed by a photocurable adhesive layer (a) of the photocurable adhesive sheet (a), and the photocurable adhesive layer (a) is cured. In the self-luminous display device of claim 5, the display panel may be an LED panel in which a plurality of LED chips are arranged on one surface of a substrate. This constitution is preferable from the following points of view: in the self-luminous display device according to claim 5, the photocurable adhesive layer (a) filled in the fine level difference between the light emitting elements (LED chips) without a gap can prevent reflection of metal wiring or the like on the substrate, prevent color mixing of RGB, and improve contrast.
The self-luminous display device of the aforementioned 5 th aspect of the present invention can be manufactured by a method including the following steps.
A step of laminating a photocurable adhesive layer (a) of a photocurable adhesive sheet (a) on a display panel having a plurality of light-emitting elements arranged on one surface of a substrate, and sealing the light-emitting elements with the photocurable adhesive layer (a); and
and (c) curing the photocurable adhesive layer (a) by irradiating it with ultraviolet light.
Since the photocurable adhesive layer (a) before curing has excellent level difference absorption properties, it sufficiently follows the fine level difference between the light-emitting elements, and adheres without leaving air bubbles and without leaving gaps. The photocurable adhesive layer (a) is cured by irradiation with ultraviolet light, and thus has excellent processability.
In the method for manufacturing a self-luminous display device according to claim 5, the ultraviolet ray is preferably an ultraviolet ray having a wavelength of less than 300 nm. This structure is preferable in that the photocurable adhesive layer (a) is cured by ultraviolet irradiation to form a crosslinked structure in the benzophenone structure, thereby exhibiting excellent processability.
ADVANTAGEOUS EFFECTS OF INVENTION
The adhesive composition, the photocurable adhesive layer, and the photocurable adhesive sheet of the present invention have high light-shielding properties against visible light and excellent level difference absorption, and therefore, when used in the production of a self-luminous display device, they fill the level differences between a plurality of light-emitting elements without gaps, prevent reflection from metal wiring, suppress color mixing between a plurality of light-emitting elements, and improve contrast. Further, the curing by the irradiation of ultraviolet rays improves the workability, and the occurrence of glue shortage at the time of cutting and the occurrence of overflow and sagging of the adhesive layer from the end portion at the time of keeping can be suppressed. Therefore, by using the adhesive composition, the photocurable adhesive layer, and the photocurable adhesive sheet of the present invention for the production of a self-luminous display device, a self-luminous display device having an improved function of preventing reflection of metal wiring or the like and an improved contrast can be efficiently produced.
Drawings
Fig. 1 is a view (sectional view) schematically showing one embodiment of a photocurable adhesive sheet according to the present invention.
Fig. 2 is a view (sectional view) schematically showing one embodiment of the photocurable adhesive sheet of the present invention.
Fig. 3 is a view (sectional view) schematically showing one embodiment of the photocurable adhesive sheet of the present invention.
Fig. 4 is a schematic view (cross-sectional view) showing one embodiment of a self-luminous display device (mini/micro LED display device) of the present invention.
Fig. 5 is a schematic view (cross-sectional view) showing the steps of one embodiment of a method for manufacturing a self-luminous display device (mini/micro LED display device) according to the present invention.
Detailed Description
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 only exemplary.
In this specification, "acrylic polymer" refers to a polymer derived from a monomer component containing more than 50 wt% of an acrylic monomer (preferably more than 70 wt%, for example, more than 90 wt%). The acrylic monomer is a monomer derived from a monomer having at least 1 (meth) acryloyl group in 1 molecule. In this specification, "(meth) acryloyl group" is a generic name of acryloyl group and methacryloyl group. Likewise, "(meth) acrylate" is a generic term for both acrylate and methacrylate, and "(meth) acrylic acid" is a generic term for both acrylic acid and methacrylic acid.
In this specification, "ethylenically unsaturated compound" means a compound having at least 1 ethylenically unsaturated group in the molecule. Examples of the ethylenically unsaturated group include a (meth) acryloyl group, a vinyl group, and an allyl group. Hereinafter, a compound having 1 ethylenically unsaturated group may be referred to as a "monofunctional monomer", and a compound having 2 or more ethylenically unsaturated groups may be referred to as a "polyfunctional monomer". In addition, a compound having X ethylenically unsaturated groups in the polyfunctional monomer may be sometimes referred to as "X functional monomer".
In this specification, the binder composition containing the ethylenically unsaturated compound means that the ethylenically unsaturated compound is contained in the form of a partial polymer unless otherwise specified. Such a partial polymer is usually a mixture comprising the above-mentioned ethylenically unsaturated compound (unreacted monomer) in which the ethylenically unsaturated group is unreacted and the above-mentioned ethylenically unsaturated compound in which the ethylenically unsaturated group is polymerized.
In this specification, the total monomer components constituting the adhesive composition means the total amount of the monomer components constituting the polymer contained in the adhesive composition and the monomer components contained in the adhesive composition in the form of unreacted monomers. The composition of the monomer component constituting the pressure-sensitive adhesive composition generally substantially matches the composition of the monomer component constituting the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition and the composition of the monomer component constituting the photo-cured product thereof.
In this specification, the "active energy ray" is a concept including light such as ultraviolet light, visible light, and infrared ray, radiation such as α ray, β ray, γ ray, electron ray, neutron ray, and X ray, and the like.
[ adhesive composition (A) ]
The adhesive composition according to claim 1, which contains a colorant and a polymer (a) having a benzophenone structure in a side chain, has a maximum value of transmittance at a wavelength of 200 to 400nm which is larger than a maximum value of transmittance at a wavelength of 400 to 700 nm.
The pressure-sensitive adhesive composition according to claim 2 of the present invention contains a colorant and a partial polymer of a mixture of monomer components constituting the polymer (a) having a benzophenone structure in a side chain or a mixture of monomer components constituting the polymer (a) having a benzophenone structure in a side chain, and the maximum value of transmittance at a wavelength of 200 to 400nm of the pressure-sensitive adhesive composition is larger than the maximum value of transmittance at a wavelength of 400 to 700 nm.
The adhesive composition according to aspects 1 and 2 of the present invention (adhesive composition (a)) may further contain an ethylenically unsaturated compound (B).
The pressure-sensitive adhesive composition (A) may contain, in addition to the above, a photopolymerization initiator (C) which absorbs ultraviolet light having a wavelength of 300 to 500nm 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 where the mixture is composed of a single monomer component and a case where the mixture is composed of 2 or more monomer components. The "partial polymer of a mixture of monomer components" refers to a composition in which 1 or 2 or more monomer components among the monomer components constituting the "mixture of monomer components" are partially polymerized.
The pressure-sensitive adhesive composition (a) may have any form, and examples thereof include a solvent type, an emulsion type, a hot-melt type (hot-melt type), a non-solvent type (an active energy ray-curable type, for example, a monomer mixture, or a monomer mixture and a partial polymer thereof). The pressure-sensitive adhesive composition (a) of the present invention is preferably an active energy ray-curable pressure-sensitive adhesive composition in view of obtaining a pressure-sensitive adhesive layer having excellent appearance. In the present specification, the adhesive composition refers to a composition for forming an adhesive layer, including a composition for forming an adhesive.
The pressure-sensitive adhesive composition (a) is not particularly limited, and examples thereof include: a composition comprising the BP polymer (A) as an essential component; and a composition containing a mixture of monomer components constituting the BP polymer (A) or a partial polymer thereof as an essential component. The former includes, for example, a so-called solvent-based pressure-sensitive adhesive composition and a water-dispersed pressure-sensitive adhesive composition (emulsion-based pressure-sensitive adhesive composition), and the latter includes, for example, a so-called active energy ray-curable pressure-sensitive adhesive composition.
The adhesive composition (a) may be a solvent-based one as described above. The solvent is not particularly limited as long as it is an organic compound that can be used as a solvent, and examples thereof include: hydrocarbon solvents such as cyclohexane, hexane, and heptane; aromatic solvents such as toluene and xylene; ester solvents such as ethyl acetate and methyl acetate; ketone solvents such as acetone and methyl ethyl ketone; and alcohol solvents such as methanol, ethanol, butanol, and isopropanol. The solvent may be a mixed solvent containing 2 or more solvents.
The adhesive composition (a) may be an acrylic adhesive composition in which more than 50 wt% (preferably more than 70 wt%, for example more than 90 wt%) of the total monomer components constituting the adhesive composition is an acrylic monomer.
The maximum value of the transmittance at a wavelength of 200 to 400nm (preferably 330 to 400 nm) of the pressure-sensitive adhesive composition (A) 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 permeability to visible light (wavelength of 400 to 700 nm), that is, has high light-shielding property. The photocurable adhesive layer (a) formed from a cured product of the adhesive composition (a) having excellent light-shielding properties against visible light seals a fine level difference between a metal wiring layer of a self-luminous display device (mini/micro LED display device) and a light-emitting element (LED chip) without a gap, thereby preventing reflection due to the metal wiring and the like, preventing color mixing of the light-emitting element (LED chip), and improving the contrast of an image.
On the other hand, the pressure-sensitive adhesive composition (A) has a higher transmittance in the ultraviolet region (wavelength of 200 to 400nm, preferably 330 to 400 nm) than in the visible light. Therefore, the photocurable adhesive layer (a) formed from the cured product of the adhesive composition (a) can form a crosslinked structure from a benzophenone structure by irradiation with ultraviolet rays and can be cured. The photocurable adhesive layer (a) cured by ultraviolet irradiation has improved processability, and can prevent the adhesive layer from overflowing from the edge and sagging during cutting and storage.
In the present specification, the "maximum value of transmittance at a wavelength of 200 to 400 nm" means the highest transmittance in a range of a wavelength of 200 to 400 nm. For example, when there is a maximum value of transmittance in a region of a wavelength of 200 to 400nm, the maximum value becomes the maximum value of transmittance. When the maximum value of the transmittance is not present in the region of the wavelength of 200 to 400nm, the higher transmittance among the transmittances at the wavelength of 200nm or 400nm becomes the maximum value. The same applies to "the maximum value of transmittance at a wavelength of 330 to 400 nm" and "the maximum value of transmittance at a wavelength of 400 to 700 nm".
The maximum value of the transmittance at a wavelength of 400 to 700nm (visible light region) of the pressure-sensitive adhesive composition (a) may be, for example, 80% or less, or 70% or less, or 60% or less, or 50% or less, or 40% or less, or 30% or less, or 20% or less, or 10% or less, or 5% or less.
In a preferred embodiment of the present invention, the average transmittance at a wavelength of 200 to 400nm (preferably 330 to 400 nm) of the pressure-sensitive adhesive composition (a) is higher than the average transmittance at a wavelength of 400 to 700 nm. The average transmittance of the pressure-sensitive adhesive composition (a) at a wavelength of 400 to 700nm (visible light region) is, for example, 80% or less, or 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.
[ coloring agent ]
The binder composition (a) comprises a colorant. The colorant is not particularly limited, and is preferably a colorant (a)) having a maximum value of transmittance at a wavelength of 200 to 400nm (preferably 330 to 400 nm) that is greater than a maximum value of transmittance at a wavelength of 400 to 700 nm.
The configuration in which the maximum value of the transmittance at a wavelength of 200 to 400nm (preferably 330 to 400 nm) of the pressure-sensitive adhesive composition (a) is larger than the maximum value of the transmittance at a wavelength of 400 to 700nm is not particularly limited, and can be preferably realized by including the colorant (a) in the pressure-sensitive adhesive composition (a).
When the binder composition (a) contains the colorant (a), the transmittance of visible light (wavelength of 400 to 700 nm) is reduced, that is, the light-shielding property is improved, while the transmittance in the ultraviolet region (wavelength of 200 to 400nm, preferably 330 to 400 nm) is higher than that of visible light.
The maximum value of the transmittance of the colorant (a) at a wavelength of 400 to 700nm (visible light region) may be, 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.
In a preferred embodiment of the present invention, the colorant (A) has an average transmittance at a wavelength of 200 to 400nm (preferably 330 to 400 nm) which is higher than the average transmittance at a wavelength of 400 to 700 nm. The colorant (A) may have an average transmittance at a wavelength of 400 to 700nm (visible light region) of, for example, 80% or less, or 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.
The transmittance of the colorant can be measured using a solution or dispersion diluted with an appropriate solvent or dispersion medium (an organic solvent with low absorption in the wavelength range of 200 to 700 nm) such as Tetrahydrofuran (THF) so that the transmittance at a wavelength of 400nm is about 50 to 60%.
The colorant may be a dye or a pigment as long as it can be dissolved or dispersed in the binder composition (a). The dye is preferable because it can realize low haze even when added in a small amount, has no sedimentation property like a pigment, and is easily uniformly distributed. Further, pigments are also preferable in that they have high color developability even when added in a small amount. When a pigment is used as the colorant, it is preferable that the conductivity is 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-transmitting BLACK pigment include "9050BLACK", "9256BLACK", "9170BLACK", "UVBK-0001" manufactured by TOKUSHIKI, "UB-1" manufactured by Mitsubishi Materials Electronic Chemicals Co., ltd. Examples of the black dye having ultraviolet light permeability include "SOC-L-0123" manufactured by Orient Chemical Industries Co., ltd.
The content of the colorant in the adhesive composition (a) may be, for example, about 0.01 to 20 parts by weight, preferably about 0.1 to 10 parts by weight, based on 100 parts by weight of the adhesive composition (a), and may be appropriately set according to the kind of the colorant, the color tone and the light transmittance of the photocurable adhesive layer (a), and the like. The colorant may be added in the form of a solution or dispersion obtained by dissolving or dispersing in an appropriate solvent.
[ Polymer (A) having a benzophenone Structure in the side chain ]
As the base polymer constituting the adhesive composition (a) of the present invention, a polymer (a) having a benzophenone structure in a side chain (BP polymer (a)) is contained. That is, the adhesive composition (a) of the present invention is an adhesive composition containing the BP polymer (a) as a base polymer. The BP polymer (a) may be used alone or in combination of 2 or more.
As the monomer component that can constitute the BP polymer (a), a compound having an ethylenically unsaturated group and a benzophenone structure in the molecule (hereinafter sometimes referred to as "ethylenically unsaturated BP") is contained, and an ethylenically unsaturated compound other than the ethylenically unsaturated BP (hereinafter sometimes referred to as "other ethylenically unsaturated compound") may be further contained.
Suitable examples of the BP polymer (a) include acrylic polymers having a benzophenone structure in a side chain. The BP polymer (a) is preferably a polymer substantially free of an ethylenically unsaturated group.
In this specification, "benzophenone structure" refers to the general formula: ar (Ar) 1 -(C＝O)-Ar 2 -, or-Ar 3 -(C＝O)-Ar 2 A diaryl ketone structure as shown. Here, ar in the above general formula 1 Selected from phenyl groups optionally having substituents. Ar in the above general formula 2 、Ar 3 Each independently selected from phenylene optionally having substituents. Ar (Ar) 2 And Ar 3 May be the same or different. The benzophenone structure can be excited by irradiation with ultraviolet rays, and in this excited state, hydrogen radicals can be abstracted from other molecules or other parts of the molecule.
The photocurable adhesive layer (a) formed from a cured product of the aforementioned adhesive composition (a) containing the BP polymer (a) may contain a benzophenone structure. The benzophenone structure is excited by ultraviolet irradiation, and can form a crosslinked structure by a hydrogen radical abstraction reaction, thereby curing the photocurable adhesive layer (a).
As the BP polymer (a), the above general formula: ar (Ar) 1 -(C＝O)-Ar 2 Ar in (E-Ar) 1 Is phenyl optionally having a substituent, and Ar 2 A polymer having a benzophenone structure in a side chain, which is a phenylene group optionally having a substituent. Ar above 1 And Ar 2 When at least one of (1) or more substituents is present, each substituent may be independently selected from the group consisting of an alkoxy group (e.g., an alkoxy group having 1 to 3 carbon atoms, preferably a methoxy group), a halogen atom (e.g., F, cl, br, etc., preferably Cl or Br), a hydroxyl group, an amino group, and a carboxyl group.
The BP polymer (a) may have a side chain in which the benzophenone structure is directly bonded to the main chain as described above, or may have a side chain in which one or more kinds of ester bonds, oxyalkylene structures, and the like are bonded to the main chain. Suitable examples of the BP polymer (a) include polymers comprising repeating units derived from an ethylenically unsaturated BP. The above repeating unit may be a polymerized residue obtained by reacting 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, 4-acryloyloxy-4 ' -bromobenzophenone, 2-hydroxy-4-acryloyloxybenzophenone and the like optionally having a substituent; acryloxy alkoxy benzophenones optionally having substituents such as 4- [ (2-acryloxy) ethoxy ] benzophenone, 4- [ (2-acryloxy) ethoxy ] -4' -bromobenzophenone and the like; methacryloyloxybenzophenone optionally having a substituent such as 4-methacryloyloxybenzophenone, 4-methacryloyloxy-4 ' -methoxybenzophenone, 4-methacryloyloxy-4 ' -bromobenzophenone, 4-methacryloyloxyethoxy-4 ' -bromobenzophenone, 2-hydroxy-4-methacryloyloxybenzophenone and the like; methacryloyloxyalkoxybenzophenones optionally having a substituent such as 4- [ (2-methacryloyloxy) ethoxy ] benzophenone, 4- [ (2-methacryloyloxy) ethoxy ] -4' -methoxybenzophenone and the like; and vinyl benzophenones optionally having substituents such as 4-vinyl benzophenone, 4 '-bromo-3-vinyl benzophenone, and 2-hydroxy 4-methoxy-4' -vinyl benzophenone, but are not limited thereto. The ethylenically unsaturated BP may be used singly or in combination of two or more for the preparation of the BP polymer (a). The ethylenically unsaturated BP can be synthesized by a known method, using a commercially available substance. From the viewpoint of reactivity and the like, an ethylenically unsaturated BP having a (meth) acryloyl group, that is, an ethylenically unsaturated BP belonging to an acrylic monomer can be preferably used.
The aforementioned BP polymer (a) may be a copolymer having a repeating unit derived from an ethylenically unsaturated BP and a repeating unit derived from an ethylenically unsaturated compound other than an ethylenically unsaturated BP (other ethylenically unsaturated compound). Such BP polymer (A) may be a copolymer of monomer components comprising the above-mentioned ethylenically unsaturated BP and the above-mentioned other ethylenically unsaturated compound. The BP polymer may be a copolymer obtained by copolymerizing a partial polymer (prepolymer) of a monomer mixture consisting only of the other ethylenically unsaturated compound with the ethylenically unsaturated BP. As the other ethylenically unsaturated compound, one or more acrylic monomers can be preferably used. Suitable examples of the BP polymer (a) include acrylic BP polymers in which more than 50 wt% (preferably more than 70 wt%, for example, more than 90 wt%) of the monomer components constituting the BP polymer (a) are acrylic monomers.
The monomer component constituting the BP polymer (a) may contain one or two or more kinds selected from alkyl (meth) acrylates having an alkyl group at the ester terminal as the above-mentioned other ethylenically unsaturated compound. Hereinafter, an alkyl (meth) acrylate having a linear or branched alkyl group having not less than X and not more than Y at the ester end may be referred to as "C (meth) acrylate X-Y Alkyl ester ". The monomer component constituting the BP polymer (A) preferably contains at least (meth) acrylic acid C 1-20 The alkyl ester as the other monomer more preferably contains (meth) acrylic acid C 4-20 Alkyl ester, further preferably (meth) acrylic acid C 4-18 Alkyl esters (e.g. acrylic acid C) 4-9 Alkyl esters).
As (meth) acrylic acid C 1-20 Non-limiting specific examples of the alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, nonadecyl (meth) acrylate, and eicosyl (meth) acrylate. Particularly preferred alkyl (meth) acrylates include n-Butyl Acrylate (BA), 2-ethylhexyl acrylate (2 EHA), isononyl acrylate, and the like. Other specific examples of the alkyl (meth) acrylate that can be preferably used include n-Butyl Methacrylate (BMA), 2-ethylhexyl methacrylate (2 EHMA), isostearyl acrylate (iSTA), and the like. The alkyl (meth) acrylate may be used singly in 1 kind or in combination of 2 or more kinds. The monomer component constituting the BP polymer (a) may contain one or two or more species selected from copolymerizable monomers described later as the other ethylenically unsaturated compound described above.
The adhesive composition (a) may be a photocurable acrylic adhesive composition in which more than 50% by weight (preferably more than 70% by weight, for example, more than 90% by weight) of all monomer components constituting the adhesive composition are acrylic monomers. The photocurable acrylic adhesive composition is photocured to form an acrylic photocured product.
The weight average molecular weight (Mw) of the BP polymer (A) is not particularly limited, and may be, for example, 0.5X 10 4 ～500×10 4 Left and right. The Mw of the BP polymer (A) is usually 1X 10 from the viewpoints of the cohesiveness of the photocurable adhesive layer (A), the handling properties of the photocurable adhesive sheet (A), and the like 4 The above is appropriate, and 5X 10 is preferable 4 Above, 10 × 10 4 Above, can be 15 × 10 4 Above, 20 × 10 may be used 4 The above. In addition, from the viewpoint of the level difference absorption of the photocurable adhesive layer (a), the Mw of the BP polymer (a) is usually 200 × 10 4 The following are suitable, and 150X 10 is preferable 4 May be 100X 10 or less 4 Hereinafter, it may be 70X 10 4 Hereinafter, the value may be 50 × 10 4 The following.
The weight average molecular weight (Mw) of the polymer is a value in terms of standard polystyrene obtained by Gel Permeation Chromatography (GPC). As the GPC apparatus, for example, the 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, from-80 ℃ to 150 ℃, from-80 ℃ to 50 ℃ or lower, or from-80 ℃ to 10 ℃ or lower. From the viewpoint of the level difference absorption of the photocurable adhesive layer (A), the Tg of the BP polymer (A) is suitably lower than 0 ℃, and is preferably-10 ℃ or lower, may be-20 ℃ or lower, may be-30 ℃ or lower, may be-40 ℃ or lower, or may be-50 ℃ or lower. From the viewpoint of improving the cohesive property of the photocurable adhesive layer (a) and the processability after photocuring, the Tg of the BP polymer (a) is usually favorably not less than-75 ℃ but may be not less than-70 ℃. In some embodiments, the Tg of BP polymer (A) may be-55 ℃ or higher, or may be-45 ℃ or higher. The Tg of the BP polymer (A) can be adjusted by the kind and amount of the monomer components constituting the BP polymer.
Here, the glass transition temperature (Tg) of the polymer is a glass transition temperature determined by the Fox equation based on the composition of the monomer components constituting the polymer. The above-mentioned Fox formula is a relational expression between Tg of the copolymer and glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each monomer constituting the copolymer, as shown below.
1/Tg＝Σ(Wi/Tgi)
In the above Fox formula, tg represents the glass transition temperature (unit: K) of the copolymer, wi represents the weight fraction of the monomer i in the copolymer (copolymerization ratio on a weight basis), and Tgi represents the glass transition temperature (unit: K) of the homopolymer of the monomer i.
The glass transition temperature of the homopolymer used for calculation of Tg was determined by the values described in the publicly known data. For example, for the monomers listed below, the following values are used as the glass transition temperatures of the homopolymers of the monomers.
2-ethylhexyl acrylate: -70 deg.C
N-butyl acrylate: -55 deg.C
Isostearyl acrylate: -18 deg.C
Methyl methacrylate: 105 ℃ C
Methyl acrylate: 8 deg.C
Cyclohexyl acrylate: 15 deg.C
N-vinyl-2-pyrrolidone: 54 deg.C
2-hydroxyethyl acrylate: -15 deg.C
4-hydroxybutyl acrylate: -40 deg.C
Isobornyl acrylate: 94 deg.C
Acrylic acid: 106 deg.C
Methacrylic acid: 228 deg.C
For the glass transition temperature of a homopolymer of a monomer other than those exemplified above, the value described in "Polymer Handbook" (3 rd edition, john Wiley & Sons, inc., 1989) was used. When a plurality of values are described in this document, the highest value is used. As the monomer having a glass transition temperature of a homopolymer, which is not described in the above-mentioned Polymer Handbook, a value obtained by the measurement method described in Japanese patent application laid-open No. 2007-51271 is used. The nominal value of the glass transition temperature may be used for a polymer provided by a manufacturer or the like.
The BP polymer (a) is preferably: the polymer contains, for example, about 0.5mg or more of benzophenone structure in terms of 4-benzoylphenyl acrylate per 1g of the polymer. Hereinafter, the value obtained by converting the number of benzophenone structures contained in 1g of BP polymer into the amount of 4-benzoylphenyl acrylate is sometimes referred to as BP equivalent (unit: mg/g) of the BP polymer. For example, the BP equivalent of the polymer is calculated to be 10mg/g per 1g comprising 40. Mu. Mol of benzophenone structure.
From the viewpoint of obtaining a higher photocuring effect (for example, an effect of improving processability by photocuring), the BP equivalent of the BP polymer (a) is preferably 0.1mg/g or more in general, and may be 0.5mg/g or more, 1mg/g or more, 5mg/g or more, 8mg/g or more, 10mg/g or more, 15mg/g or more, or 20mg/g or more in some embodiments. In some embodiments, the BP equivalent of the BP polymer (a) is usually preferably 100mg/g or less, and may be 80mg/g or less, 60mg/g or less, 40mg/g or less, 25mg/g or less, or 15mg/g or less, from the viewpoint of improving the impact resistance and peel strength of a bonded portion formed of a cured product of light. 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 lowering the peeling force by photocuring, performing rework, and maintenance, the BP equivalent is preferably 50mg/g or more, and may be 100mg/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 may be set so that the level difference absorption of the photocurable pressure-sensitive adhesive layer (a) and the processability of a photocurable material thereof are appropriately balanced. In some embodiments, the weight fraction of the BP polymer (a) may be, for example, 1 wt% or more, and usually 5 wt% or more is suitable, and may be 10 wt% or more, 15 wt% or more, 25 wt% or more, 35 wt% or more, 45 wt% or more, or 55 wt% or more. When the weight fraction of the BP polymer (A) is increased, G 'a10/G' b85 described later tends to be increased.
The binder composition (a) may be used in such a manner that the weight fraction of the BP polymer (a) is substantially 100 wt% (for example, 99.5 wt% or more). In addition, from the viewpoint of ease of adhesive performance, the weight fraction of the BP polymer (a) in the adhesive composition (a) may be, for example, less than 99 wt%, less than 95 wt%, less than 85 wt%, less than 70 wt%, less than 50 wt%, or less than 40 wt% in some embodiments.
It is preferable to contain, for example, about 0.1mg or more of benzophenone structure per 1g of the adhesive composition (A) in terms of 4-benzoylphenyl acrylate. Hereinafter, the weight in terms of 4-benzoylphenyl acrylate having a benzophenone structure per 1g of the adhesive composition (A) may be referred to as BP equivalent (unit: mg/g) of the adhesive composition. From the viewpoint of obtaining a higher photocuring effect (for example, an effect of improving processability by photocuring), the BP equivalent of the pressure-sensitive adhesive composition is usually preferably 0.3mg/g or more, and may be 0.5mg/g or more, 1mg/g or more, 5mg/g or more, 10mg/g or more, or 20mg/g or more in some embodiments. In some embodiments, the BP equivalent weight of the adhesive composition is usually preferably 100mg/g or less, and may be 80mg/g or less, 60mg/g or less, 40mg/g or less, 25mg/g or less, or 15mg/g or less, from the viewpoint of impact resistance of a bonding portion formed from a cured product and suppression of strain in the cured product.
[ ethylenically unsaturated Compound (B) ]
The adhesive composition (A) may further contain an ethylenically unsaturated compound (B) in addition to the BP polymer (A). In the case where the adhesive composition (a) is a solventless (active energy ray-curable) adhesive composition, the adhesive composition (a) preferably contains the ethylenically unsaturated compound (B). On the other hand, when the pressure-sensitive adhesive composition (a) is a solvent-type or emulsion-type pressure-sensitive adhesive composition, the ethylenically unsaturated compound (B) may not be contained.
In addition, in the case where the adhesive composition (a) contains a partial polymer of the mixture of monomer components constituting the BP polymer (a) or the mixture of monomer components constituting the BP polymer (a), the above-mentioned other ethylenically unsaturated compound may be contained as the monomer component, and therefore, the ethylenically unsaturated compound (B) may not be necessarily contained. When the adhesive composition (A) containing the mixture of monomer components or a partial polymer thereof contains the ethylenically unsaturated compound (B), the ethylenically unsaturated compound (B) may be the same as or different from the other ethylenically unsaturated compounds described above.
Examples of the compound which can be used as the ethylenically unsaturated compound (B) include the above-mentioned alkyl (meth) acrylate and the above-mentioned ethylenically unsaturated BP. Of these, it is preferable to use at least an alkyl (meth) acrylate (e.g., C (meth) acrylate) 1-20 Alkyl esters, more preferably (meth) acrylic acid C 4-18 Alkyl ester, more preferably acrylic acid C 4-9 Alkyl esters). As particularly preferred alkyl (meth) acrylates, n-Butyl Acrylate (BA) and 2-ethylhexyl acrylate (2 EHA) may be mentioned. Other specific examples of the alkyl (meth) acrylate which can be preferably used include isononyl acrylate, n-Butyl Methacrylate (BMA), 2-ethylhexyl methacrylate (2 EHMA), isostearyl acrylate (iSTA), and the like. The alkyl (meth) acrylate may be used singly in 1 kind or in combination of 2 or more kinds. In some embodiments, the ethylenically unsaturated compound (B) preferably comprises either or both of n-Butyl Acrylate (BA) and 2-ethylhexyl acrylate (2 EHA), more preferably at least BA.
The ethylenically unsaturated compound (B) may contain acrylic acid C in a proportion of 40% by weight or more 4-9 An alkyl ester. Acrylic acid C 4-9 The ratio of the alkyl ester in the monomer component may be, for example, 50% by weight or more, 60% by weight or more, or 65% by weight or more.In addition, from the viewpoint of improving the cohesive property of the photocurable adhesive layer (a), acrylic acid C 4-9 The proportion of the alkyl ester in the ethylenically unsaturated compound (B) is usually preferably 99.5% by weight or less, and may be 95% by weight or less, 85% by weight or less, 70% by weight or less, or 60% by weight or less.
Other examples of the compound usable as the ethylenically unsaturated compound (B) include ethylenically unsaturated compounds (copolymerizable monomers) copolymerizable with the alkyl (meth) acrylate. As the copolymerizable monomer, a monomer having a polar group (for example, a carboxyl group, a hydroxyl group, a nitrogen atom-containing ring, etc.) can be suitably used. The monomer having a polar group may contribute to, for example, introduction of a crosslinking point into a polymer containing a repeating unit derived from the monomer, or increase the cohesive force of the photocurable adhesive layer (a). The copolymerizable monomers may be used singly or in combination of two or more.
Specific non-limiting examples of the copolymerizable monomer include the following.
Carboxyl group-containing monomer: such as 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: such as maleic anhydride, itaconic anhydride.
Hydroxyl group-containing monomer: examples of the (meth) acrylic acid include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, and (4-hydroxymethylcyclohexyl) methyl (meth) acrylate.
Sulfonic acid group-or phosphoric acid group-containing monomer: for example, styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2- (meth) acrylamido-2-methylpropanesulfonic acid, (meth) acrylamidopropanesulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalenesulfonic acid, 2-hydroxyethylacryloyl phosphate, and the like.
Epoxy group-containing monomer: examples of the epoxy group-containing acrylate include glycidyl (meth) acrylate, 2-ethylglycidyl (meth) acrylate, allyl glycidyl ether, and glycidyl (meth) acrylate.
A cyano group-containing monomer: such as acrylonitrile, methacrylonitrile, and the like.
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 monomer: such as (meth) acrylamide; n, N-dialkyl (meth) acrylamides such as N, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-dipropyl (meth) acrylamide, N-diisopropyl (meth) acrylamide, N-di (N-butyl) (meth) acrylamide, and N, N-di (tert-butyl) (meth) acrylamide; n-alkyl (meth) acrylamides such as N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, and N-N-butyl (meth) acrylamide; n-vinylcarboxylic acid amides such as N-vinylacetamide; a monomer having a hydroxyl group and an amide group, for example, N-hydroxyalkyl (meth) acrylamides 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, and N- (4-hydroxybutyl) (meth) acrylamide; monomers having an alkoxy group and an amide group, for example, N-alkoxyalkyl (meth) acrylamides such as N-methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, and N-butoxymethyl (meth) acrylamide; and N, N-dimethylaminopropyl (meth) acrylamide, N- (meth) acryloylmorpholine, and the like.
Amino group-containing monomers: for example, aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, tert-butylaminoethyl (meth) acrylate. Monomer having epoxy group: such as glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, allyl glycidyl ether.
Monomer having 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) acryloylpiperidine, N- (meth) acryloylpyrrolidine, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinodione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, N-vinylisothiazole, N-vinylpyridazine and the like (for example, lactams such as N-vinyl-2-caprolactam) can be mentioned.
Monomer having succinimide skeleton: for example, N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxohexamethylene succinimide, N- (meth) acryloyl-8-oxohexamethylene succinimide, etc.
Maleimide group: such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide, etc.
Itaconimides: such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-lauryl itaconimide, etc.
Aminoalkyl (meth) acrylates: such as aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, N-diethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate.
Alkoxy group-containing monomers: alkoxyalkyl (meth) acrylates (alkoxyalkyl (meth) acrylates) such as 2-methoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxypropyl (meth) acrylate, and the like; alkoxyalkylene glycol (meth) acrylates (for example, alkoxypolyalkylene glycol (meth) acrylates) such as methoxyethylene glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, and methoxypolypropylene glycol (meth) acrylate.
Alkoxysilyl group-containing monomer: for example, alkoxysilyl group-containing (meth) acrylates such as 3- (meth) acryloyloxypropyltrimethoxysilane, 3- (meth) acryloyloxypropyltriethoxysilane, 3- (meth) acryloyloxypropylmethyldimethoxysilane and 3- (meth) acryloyloxypropylmethyldiethoxysilane, and alkoxysilyl group-containing vinyl compounds such as vinyltrimethoxysilane and vinyltriethoxysilane.
Vinyl esters: such as vinyl acetate, vinyl propionate, and the like.
Vinyl ethers: examples of the vinyl alkyl ether include methyl vinyl ether and ethyl vinyl ether.
Aromatic vinyl compound: such as styrene, alpha-methylstyrene, vinyltoluene, and the like.
Olefins: such as ethylene, butadiene, isoprene, isobutylene, and the like.
(meth) acrylate having alicyclic hydrocarbon group: examples of the alicyclic hydrocarbon group-containing (meth) acrylates include cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and adamantyl (meth) acrylate.
(meth) acrylate having an aromatic hydrocarbon group: for example, aromatic hydrocarbon group-containing (meth) acrylates such as phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, and benzyl (meth) acrylate.
And heterocyclic ring-containing (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate, halogen atom-containing (meth) acrylates such as chloroethenyl-and fluorine atom-containing (meth) acrylates, silicon atom-containing (meth) acrylates such as silicone (meth) acrylates, and (meth) acrylates derived from terpene compound derivative alcohols.
When such a copolymerizable monomer is used, the amount thereof is not particularly limited, and is usually preferably 0.01% by weight or more of the total monomer components constituting the pressure-sensitive adhesive composition (a). From the viewpoint of more effectively exhibiting the effect of using the copolymerizable monomer, the amount of the copolymerizable monomer to be used (i.e., the weight fraction of the copolymerizable monomer in the entire monomer components) may be 0.1% by weight or more, or may be 0.5% by weight or more, based on the entire monomer components. From the viewpoint of easily obtaining the balance of adhesive properties, the amount of the copolymerizable monomer used is usually preferably 50% by weight or less, and more preferably 40% by weight or less, of the total monomer components.
The copolymerizable monomer may contain a monomer having a nitrogen atom. By using a monomer having a nitrogen atom, the cohesive force of the photocurable adhesive layer (a) can be increased, and the peel strength after photocuring can be preferably increased. As a suitable example of the monomer having a nitrogen atom, a monomer having a ring containing a nitrogen atom is mentioned. As the monomer having a nitrogen atom-containing ring, the above-exemplified ones can be used, and for example, an N-vinyl cyclic amide represented by the general formula (1) can be used.
Figure BDA0004096818070000231
Here, in the general formula (1), R 1 Is an organic radical having a valence of 2, in particular- (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 used. Other suitable examples of the monomer having a nitrogen atom include (meth) acrylamide.
The amount of the monomer having a nitrogen atom (preferably, a monomer having a nitrogen atom-containing ring such as an N-vinyl cyclic amide) used is not particularly limited, and may be, for example, 1% by weight or more, 2% by weight or more, 3% by weight or more, and further 5% by weight or more, or 7% by weight or more of the total monomer components. In one embodiment, 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 components. The amount of the nitrogen atom-containing monomer used is preferably 40% by weight or less of the total monomer components, and may be 35% by weight or less, 30% by weight or less, or 25% by weight or less. In another embodiment, the amount of the nitrogen atom-containing monomer used may be, for example, 20% by weight or less, or 15% by weight or less, based on the total monomer components. Alternatively, a nitrogen atom-containing monomer may not be used as the copolymerizable monomer.
The copolymerizable monomer may contain a hydroxyl group-containing monomer. By using the hydroxyl group-containing monomer, the cohesive force of the photocurable adhesive layer (a), the degree of crosslinking (for example, crosslinking based on an isocyanate crosslinking agent) can be appropriately adjusted. The amount of the hydroxyl group-containing monomer used is not particularly limited, and may be, for example, 0.01% by weight or more, 0.1% by weight or more, 0.5% by weight or more, 1% by weight or more, or 5% by weight or more or 10% by weight or more of the total monomer components. In some embodiments, the amount of the hydroxyl group-containing monomer used is preferably 40 wt% or less, for example, 30 wt% or less, 25 wt% or less, or 20 wt% or less of the total monomer components, from the viewpoint of suppressing water absorption of the photocurable adhesive layer (a) or a photocurable product thereof. In another embodiment, the amount of the hydroxyl group-containing monomer used may be, for example, 15% by weight or less, 10% by weight or less, or 5% by weight or less of the total monomer components. Alternatively, a hydroxyl group-containing monomer may not be used as the copolymerizable monomer.
The ratio of the carboxyl group-containing monomer to the total monomer components may be, for example, 2 wt% or less, 1 wt% or less, or 0.5 wt% or less (for example, less than 0.1 wt%). The pressure-sensitive adhesive composition (a) may not substantially contain a carboxyl group-containing monomer as a constituent monomer component thereof. Here, substantially free of the carboxyl group-containing monomer means that the carboxyl group-containing monomer is not used at least intentionally. This is advantageous from the viewpoint of metal corrosion resistance of the photocurable adhesive layer (a) formed from the adhesive composition (a) and the photocurable product thereof.
The copolymerizable monomer may contain a (meth) acrylate containing an alicyclic hydrocarbon group. This improves the cohesive force of the photocurable adhesive layer (a) and improves the peel strength after photocuring. 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 used. The amount of the alicyclic hydrocarbon group-containing (meth) acrylate 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 total monomer components. In one embodiment, the amount of the alicyclic hydrocarbon group-containing (meth) acrylate used may be 10% by weight or more, or 15% by weight or more of the total monomer components. The upper limit of the amount of the alicyclic hydrocarbon group-containing (meth) acrylate to be used is preferably about 40% by weight or less, and may be, for example, 30% by weight or less, or may be 25% by weight or less (for example, 15% by weight or less, further 10% by weight or less). Alternatively, the alicyclic hydrocarbon group-containing (meth) acrylate may not be used as the copolymerizable monomer.
The copolymerizable monomer may contain an alkoxysilyl group-containing monomer. The alkoxysilyl group-containing monomer is typically an ethylenically unsaturated compound having at least 1 (preferably 2 or more, for example 2 or 3) alkoxysilyl groups in one molecule, which is specifically exemplified above. The above alkoxysilyl group-containing monomers may be used singly in 1 kind or in combination in 2 or more kinds. By using the alkoxysilyl group-containing monomer, a crosslinked structure based on a condensation reaction (silanol condensation) of silanol groups can be introduced into the photocurable adhesive layer (a).
The amount of the alkoxysilyl group-containing monomer used is not particularly limited. In some embodiments, the amount of the alkoxysilyl group-containing monomer used may be, for example, 0.005% by weight or more, and usually 0.01% by weight or more is suitable, and may be 0.03% by weight or more, and may be 0.05% by weight or more, of the total monomer components constituting the pressure-sensitive adhesive composition (a). In addition, from the viewpoint of the level difference absorbency of the pressure-sensitive adhesive composition (a), the amount of the alkoxysilyl group-containing monomer used is preferably 1.0% by weight or less, and may be 0.5% by weight or less, or may be 0.1% by weight or less, based on the total monomer components.
As still another example of the compound usable as the ethylenically unsaturated compound (B), a polyfunctional monomer is mentioned. When the curable adhesive layer (a) is produced by curing a pressure-sensitive adhesive composition (a) containing a polyfunctional monomer, the polyfunctional monomer is reacted to obtain the curable adhesive layer (a) crosslinked with the polyfunctional monomer. 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, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene and the like; polyfunctional monomers having 3 or more functionalities such as trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and the like; other epoxy acrylates, polyester acrylates, urethane acrylates, and the like. Preferred examples thereof include 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipentaerythritol hexa (meth) acrylate. The polyfunctional monomers may be used alone in 1 kind or in combination of 2 or more kinds.
The amount of the polyfunctional monomer used is not particularly limited, and may be less than 5.0% by weight of the total monomer components constituting the pressure-sensitive adhesive composition (a). This can avoid formation of an excessive crosslinked structure during formation of the photocurable adhesive layer (a) (i.e., at a stage before photocuring), and can improve the level difference absorption of the photocurable adhesive layer (a). The amount of the polyfunctional monomer used may be, for example, 4.0% by weight or less, 3.0% by weight or less, 2.0% by weight or less, 1.0% by weight or less, 0.5% by weight or less, or 0.3% by weight or less of the total monomer components. The polyfunctional monomer may not be used. In some embodiments, the amount of the polyfunctional monomer used may be, for example, 0.001 wt% or more, 0.005 wt% or more, 0.01 wt% or more, or 0.03 wt% or more with respect to the total monomer components, from the viewpoint of providing a proper cohesive property to the photocurable adhesive layer (a).
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 adhesive composition (a) is not particularly limited, and may be set so that the level difference absorption of the photocurable adhesive layer (a) formed from the adhesive composition (a) and the processability of a photocured product thereof are appropriately balanced. In some embodiments, the weight fraction of the BP polymer (a) may be, for example, 0.5 wt% or more, usually 1 wt% or more, preferably 1.5 wt% or more, and more preferably 5 wt% or more, and from the viewpoint of improving the effect of photocuring, may be 10 wt% or more, 15 wt% or more, 25 wt% or more, 35 wt% or more, 45 wt% or more, and 55 wt% or more. In some embodiments, the weight ratio of the BP polymer (a) in the total amount may be, for example, less than 99 wt%, less than 95 wt%, less than 85 wt%, less than 70 wt%, less than 50 wt%, or less than 40 wt%, from the viewpoints of ease of preparation, coatability, and the like of the adhesive composition (a).
The ratio of the weight of the organic solvent to the weight of the entire pressure-sensitive adhesive composition (a) may be, for example, 30 wt% or less, and is favorably 20 wt% or less, and is preferably 10 wt% or less, and more preferably 5 wt% or less. In some embodiments, the weight ratio of the organic solvent may be 3 wt% or less, may be 1 wt% or less, may be 0.5 wt% or less, may be 0.1 wt% or less, may be 0.05 wt% or less, or may not substantially contain an organic solvent.
From the viewpoint of coatability in the above-mentioned normal temperature region, etc., it is preferable that the viscosity (measured with a BH type viscometer, no.5 spindle, at 10rpm, at a measurement temperature of 30 ℃. The same applies hereinafter) of the pressure-sensitive adhesive composition (a) is 1000Pa · s or less, preferably 100Pa · s or less, more preferably 50Pa · s or less. The viscosity of the pressure-sensitive adhesive composition (a) may be, for example, 30Pa · s or less, 20Pa · s or less, 10Pa · s or less, or 5Pa · s or less. The lower limit of the viscosity of the pressure-sensitive adhesive composition (a) is not particularly limited, and is usually preferably 0.1Pa · s or more, and may be 0.5Pa · s or more, and may be 1Pa · s or more, from the viewpoint of suppressing shrinkage of the pressure-sensitive adhesive composition within the application range and overflow of the pressure-sensitive adhesive composition at the outer edge of the application range.
The adhesive composition (a) contains at least a compound having 1 ethylenically unsaturated group (i.e., a monofunctional monomer) (B1) as the ethylenically unsaturated compound (B). The monofunctional monomer (B1) can be used by selecting a corresponding compound from the above-mentioned examples of the ethylenically unsaturated compound (B). The monofunctional monomers may be used singly 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 wt% or more, 5 wt% or more, or 15 wt% or more. In some embodiments, the weight ratio of the monofunctional monomer (B1) may be 25 wt% or more, 35 wt% or more, or 45 wt% or more from the viewpoints of ease of preparation, coatability, and the like of the adhesive composition (a). The weight ratio of the monofunctional monomer (B1) in the total amount may be, for example, 99% by weight or less, usually 95% by weight or less, preferably 85% by weight or less, 75% by weight or less, 65% by weight or less, 55% by weight or less, or 45% by weight or less.
In the embodiment in which the adhesive composition (a) contains the monofunctional monomer (B1), the glass transition temperature (Tg) determined by the Fox equation based on the composition of the monofunctional monomer (B1) is not particularly limited, and may be, for example, from-80 ℃ to 250 ℃. From the viewpoint of compatibility of the polymer derived from the monofunctional monomer (B1) with other components, the Tg of the composition based on the monofunctional monomer (B1) is preferably 150 ℃ or lower, may be 100 ℃ or lower, may be 70 ℃ or lower, may be 50 ℃ or lower, or may be 30 ℃ or lower. In some embodiments, the Tg of the composition based on the monofunctional monomer (B1) is preferably less than 0 ℃, more preferably-10 ℃ or less, may be-20 ℃ or less, may be-30 ℃ or less, or may be-40 ℃ or less, from the viewpoint of the level difference absorption property of the photocurable adhesive layer (a), and the like. From the viewpoint of the cohesive property of the photocurable adhesive layer (a) and the processability after photocuring, the Tg of the composition based on the monofunctional monomer (B1) is usually favorably not less than-60 ℃, and may be not less than-54 ℃, not less than-50 ℃, not less than-45 ℃, not less than-35 ℃ or not less than-25 ℃. The Tg can be adjusted by the compound used as the monofunctional monomer and the ratio of the amount of the compound used.
In an adhesive composition (A) comprising a BP polymer (A) and a monofunctional monomer (B1), a photocurable adhesive layer (A) formed from the adhesive composition, and a photocurable cured product thereof, the Tg (hereinafter referred to as "Tg") of the BP polymer (A) A ". ) Tg (hereinafter referred to as "Tg") with a monomer composition based on a monofunctional monomer (B1) B1 ". ) May be such as to pass Tg B1 [℃]-Tg A [℃]Calculated Tg Difference [ deg.C ]](hereinafter also referred to as Δ Tg.) is set in a range of, for example, -50 ℃ or higher and 70 ℃ or lower. From the viewpoint of compatibility between the photocurable adhesive layer (a) and a photocurable material thereof, it is advantageous that the absolute value of the Tg difference is not excessively large. In some embodiments, Δ Tg may be, for example, -10 ℃ or higher, preferably 0 ℃ or higher, 7 ℃ or higher, 10 ℃ or higher, 20 ℃ or higher, or 30 ℃ or higher.
The adhesive composition (a) may contain at least a compound having 2 or more ethylenically unsaturated groups (i.e., a polyfunctional monomer) (B2) as the above ethylenically unsaturated compound (B). The polyfunctional monomer (B2) may be used alone or in combination of two or more from the above examples of the polyfunctional monomer. The amount of the polyfunctional monomer (B2) used may be set in the same manner as the ratio of the polyfunctional monomer to the total monomer components constituting the adhesive composition (a).
In the embodiment of using the monofunctional monomer (B1) and the polyfunctional monomer (B2) in combination as the ethylenically unsaturated compound (B), the weight ratio of the monofunctional monomer (B1) to the ethylenically unsaturated compound (B) may be, for example, 1 wt% or more, usually 25 wt% or more is suitable, and may be 50 wt% or more, 75 wt% or more, 95 wt% or more, or 99 wt% or more. The weight ratio of the monofunctional monomer (B1) to the ethylenically unsaturated compound (B) may be, for example, 99.9 wt% or less, or may be 99.8 wt% or less.
In the pressure-sensitive adhesive composition (a), the ethylenically unsaturated compound (B) may be contained in the form of a partial polymer, or may be contained in the form of unreacted monomers in the entire amount. The 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, the following can be appropriately selected and used: photopolymerization by irradiation with light such as ultraviolet rays; radiation polymerization by irradiation with radiation such as β -rays and γ -rays; thermal polymerization such as solution polymerization, emulsion polymerization, bulk polymerization, etc.; and various conventionally known polymerization methods. From the viewpoint of efficiency and simplicity, a photopolymerization method is preferably employed. By photopolymerization, the polymerization conversion rate (monomer conversion rate) can be easily controlled by polymerization conditions such as the irradiation amount (light amount) of light.
The polymerization conversion of the ethylenically unsaturated compound (B) in the partial polymer is not particularly limited. From the viewpoint of ease of production, coatability, and the like of the pressure-sensitive adhesive composition (a), the polymerization conversion rate is usually suitably about 50% by weight or less, and preferably about 40% by weight or less (for example, about 35% by weight or less). The lower limit of the polymerization conversion is not particularly limited, but is typically about 1% by weight or more, and is usually about 5% by weight or more.
The binder composition (a) comprising a partial polymer of the ethylenically unsaturated compound (B) can be obtained, for example, by: the entire amount of the monomer mixture containing the ethylenically unsaturated compound (B) used for the preparation of the adhesive composition is partially polymerized by a suitable polymerization method, such as a photopolymerization method. In addition, the binder composition (a) comprising a partial polymer of the olefinically unsaturated compound (B) may also be a mixture of a partial polymer of a monomer mixture comprising a part of the olefinically unsaturated compound (B) used in the preparation of the binder composition and the remaining olefinically unsaturated compound (B) or a partial polymer thereof. In the present specification, "complete polymer" means a polymerization conversion of more than 95% by weight.
The above 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 adhesive composition (a) comprising the partial polymer of the ethylenically unsaturated compound (B) and the BP polymer (a) can be obtained by setting the irradiation conditions of ultraviolet rays so that the ethylenically unsaturated group reacts and the benzophenone structure is not photoexcited. As the light source, a light source capable of irradiating ultraviolet rays containing no component having a wavelength of less than 300nm or containing a small amount of the component having the wavelength, such as the above-mentioned black light lamp or UV-LED lamp, can be preferably used.
Alternatively, the adhesive composition (A) may be prepared by preparing a partial polymer of the ethylenically unsaturated compound (B) in advance and then mixing the partial polymer with the BP polymer (A). When the ethylenically unsaturated compound (B) is irradiated with ultraviolet rays in the absence of a component having a benzophenone structure to prepare a partial polymer thereof, a light source which does not excite the benzophenone structure and a light source which does not excite the benzophenone structure can be used as the ultraviolet ray source.
In the preparation of the partial polymer of the ethylenically unsaturated compound (B), the reaction of the ethylenically unsaturated group can be promoted by using a photopolymerization initiator. As the photopolymerization initiator, ketal photopolymerization initiators, acetophenone photopolymerization initiators, benzoin ether photopolymerization initiators, acylphosphine oxide photopolymerization initiators, α -ketol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, photoactive oxime photopolymerization initiators, benzoin photopolymerization initiators, benzil photopolymerization initiators, benzophenone photopolymerization initiators, alkylphenone photopolymerization initiators, thioxanthone photopolymerization initiators, and the like can be used. It is preferable to use a photopolymerization initiator which absorbs light having a wavelength of 300nm or more (for example, light having a wavelength of 300nm or more and 500nm or less) and generates radicals. The photopolymerization initiator may be used alone in 1 kind or in an appropriate combination of 2 or more kinds.
[ photopolymerization initiator ]
The pressure-sensitive adhesive composition (a) may contain a photopolymerization initiator as necessary for the purpose of improving or imparting photocurability or the like. When the adhesive composition (a) is a solvent-free type (active energy ray-curable type) adhesive composition, the 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, the photopolymerization initiator may not be contained.
As the photopolymerization initiator, a ketal photopolymerization initiator, an acetophenone photopolymerization initiator, a benzoine ether photopolymerization initiator, an acylphosphine oxide photopolymerization initiator, an α -ketol photopolymerization initiator, an aromatic sulfonyl chloride photopolymerization initiator, a photoactive oxime photopolymerization initiator, a benzoine photopolymerization initiator, a benzil photopolymerization initiator, a benzophenone photopolymerization initiator, an alkylbenzene ketone photopolymerization initiator, a thioxanthone photopolymerization initiator, and the like can be used. The photopolymerization initiators may be used alone in 1 kind or in an appropriate combination of 2 or more kinds.
Specific examples of the ketal-based photopolymerization initiator include: 2,2-dimethoxy-1,2-diphenylethan-1-one, and the like.
Specific examples of the acetophenone-based photopolymerization initiator include: 1-hydroxycyclohexyl-phenyl-ketone, 4-phenoxydichloroacetophenone, 4-tert-butyl-dichloroacetophenone, 1- [4- (2-hydroxyethoxy) -phenyl ] -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, methoxyacetophenone and the like.
Specific examples of the benzoin ether-based photopolymerization initiator include: and substituted benzoin ethers such as benzoin ethers including benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, and benzoin isobutyl ether, and anisoin methyl ether.
Specific examples of the acylphosphine oxide-based photopolymerization initiator include: bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, and the like.
Specific examples of the α -ketol photopolymerization initiator include: 2-methyl-2-hydroxypropiophenone, 1- [4- (2-hydroxyethyl) phenyl ] -2-methylpropan-1-one, and the like.
Specific examples of the aromatic sulfonyl chloride-based photopolymerization initiator include 2-naphthalenesulfonyl chloride and the like.
Specific examples of the optically active 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 benzil-based photopolymerization initiator include benzil and the like.
Specific examples of the benzophenone-based photopolymerization initiator include: benzoylbenzoic acid, 3,3' -dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α -hydroxycyclohexyl phenyl ketone, 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, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, and the like.
As the photopolymerization initiator contained in the pressure-sensitive adhesive composition (a), a photopolymerization initiator (sometimes referred to as "photopolymerization initiator (C)") which absorbs light having a wavelength of 300nm or more (for example, light having a wavelength of 300nm or more and 500nm or less) and generates radicals can be preferably used. When the pressure-sensitive adhesive composition (a) contains the photopolymerization initiator (C), it is preferable from the viewpoint of curing the pressure-sensitive adhesive composition (a) to obtain a cured product in which the benzophenone structure of the BP polymer (a) remains.
The photopolymerization initiator may be used alone in 1 kind or in an appropriate combination of 2 or more kinds. In some embodiments, a photopolymerization initiator containing no phosphorus element in the molecule may be preferably used. The binder composition (a) may contain substantially no photopolymerization initiator containing a phosphorus element in its molecule.
The content of the photopolymerization initiator in the pressure-sensitive adhesive composition (a) is not particularly limited, and may be set so as to appropriately exhibit a desired effect. In some embodiments, the content of the photopolymerization initiator may be, for example, about 0.005 parts by weight or more, and usually 0.01 parts by weight or more is appropriate, and preferably 0.05 parts by weight or more, and may be 0.10 parts by weight or more, 0.15 parts by weight or more, or 0.20 parts by weight or more, relative to 100 parts by weight of the monomer components constituting the pressure-sensitive adhesive composition (a). By increasing the content of the photopolymerization initiator, the photocurability of the adhesive composition (a) is improved. The content of the photopolymerization initiator is preferably 5 parts by weight or less, more preferably 2 parts by weight or less, and may be 1 part by weight or less, 0.7 part by weight or less, or 0.5 part by weight or less, based on 100 parts by weight of the monomer component constituting the pressure-sensitive adhesive composition (a). From the viewpoint of suppressing gelation of the pressure-sensitive adhesive composition (a), it may be advantageous not to contain an excessive content of the photopolymerization initiator.
[ crosslinking agent ]
The pressure-sensitive adhesive composition (a) may contain, if necessary, a known crosslinking agent such as an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, a carbodiimide-based crosslinking agent, a melamine-based crosslinking agent, a urea-based crosslinking agent, a metal alkoxide-based crosslinking agent, a metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, a hydrazine-based crosslinking agent, or an amine-based crosslinking agent. As the crosslinking agent, a peroxide may also be used. When the pressure-sensitive adhesive composition (a) is a solvent-based or emulsion-based pressure-sensitive adhesive composition, it preferably contains a crosslinking agent.
The crosslinking agent can be used alone or in combination of 2 or more. The photocurable adhesive layer (a) formed from the adhesive composition (a) containing a crosslinking agent preferably contains the crosslinking agent mainly in a form after a crosslinking reaction. By using the crosslinking agent, the cohesive force and the like of the photocurable adhesive layer (a) can be appropriately adjusted.
The amount of the crosslinking agent used (the total amount of 2 or more crosslinking agents used) is not particularly limited. From the viewpoint of achieving an adhesive agent that exhibits adhesive properties such as adhesive strength and cohesive strength in a well-balanced manner, the amount of the crosslinking agent used is usually about 5 parts by weight or less, and 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, or 0.20 parts by weight or less, based on 100 parts by weight of the monomer components constituting the adhesive agent composition (a). The lower limit of the amount of the crosslinking agent to be used is not particularly limited, and may be an amount of more than 0 part by weight based on 100 parts by weight of the monomer component constituting the adhesive composition (a). In some embodiments, the amount of the crosslinking agent used may be, for example, 0.001 parts by weight or more, 0.01 parts by weight or more, 0.05 parts by weight or more, or 0.10 parts by weight or more, relative to 100 parts by weight of the monomer component constituting the adhesive composition (a).
[ chain transfer agent ]
The 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 (non-sulfur chain transfer agent) containing no sulfur atom may be used. Specific examples of the non-sulfur chain transfer agent include: anilines such as N, N-dimethylaniline and N, N-diethylaniline; terpenes such as α -pinene and terpinolene; styrenes such as α -methylstyrene and α -methylstyrene dimer; compounds having benzylidene group such as dibenzylidene acetone, cinnamyl alcohol and cinnamyl aldehyde; hydroquinone, such as 1,4-dihydroxynaphthalene; quinones such as benzoquinone and naphthoquinone; 2,3-dimethyl-2-butene, 1,5-cyclooctadiene and other olefins; alcohols such as phenol, benzyl alcohol, and allyl alcohol; benzyl hydrides such as diphenylbenzene and triphenylbenzene; and the like. The chain transfer agent may be used alone in 1 kind or in combination of 2 or more kinds. When a chain transfer agent is used, the amount thereof to be used may be, for example, about 0.01 to 1 part by weight per 100 parts by weight of the monomer component. It may also be preferably carried out without using a chain transfer agent.
Examples of other components that may be contained in the adhesive composition (a) include a silane coupling agent. By using the silane coupling agent, the peel strength to an adherend (e.g., a glass plate) can be improved. The photocurable adhesive layer (a) may contain a silane coupling agent. The photocurable adhesive layer (a) containing a silane coupling agent can be suitably formed using an adhesive composition (a) containing a silane coupling agent. The silane coupling agent may be used alone in 1 kind or in combination of 2 or more kinds.
The pressure-sensitive adhesive composition (a) may contain, as other optional components, various additives that are conventional in the field of pressure-sensitive adhesives, such as a tackifier resin (e.g., rosin-based, petroleum-based, terpene-based, phenol-based, ketone-based, etc.), a viscosity modifier (e.g., a tackifier), a leveling agent, an antioxidant, a plasticizer, a filler, a stabilizer, a preservative, an anti-aging agent, etc., as required. The various additives can be conventionally known additives, and the present invention is not particularly characterized, and therefore, detailed description thereof is omitted.
The pressure-sensitive adhesive composition (a) can exhibit good adhesive strength without using the above tackifier resin. Therefore, in some embodiments, the content of the tackifier resin in the photocurable adhesive layer (a) or the adhesive composition (a) may be, for example, less than 10 parts by weight, and further less than 5 parts by weight, relative to 100 parts by weight of the monomer component. The content of the tackifier resin may be less than 1 part by weight (for example, less than 0.5 part by weight), or less than 0.1 part by weight (not less than 0 part by weight and less than 0.1 part by weight). The photocurable adhesive layer (a) or the adhesive composition (a) may not contain a tackifier resin.
[ Photocurable adhesive layer (A) ]
The photocurable adhesive layer (a) is formed from a cured product of the adhesive composition (a) with a benzophenone structure remaining. The benzophenone structure can form a crosslinked structure by ultraviolet irradiation, and can cure the photocurable adhesive layer (a). The photocurable adhesive layer (a) before curing is in a semi-cured state with high fluidity, and exhibits excellent level difference absorption. Therefore, when the photocurable adhesive layer (a) of the photocurable adhesive sheet (a) is bonded to a display panel in which light-emitting elements (LED chips) are arranged at a high density, the photocurable adhesive layer (a) sufficiently follows the fine height difference between the light-emitting elements (LED chips), and the light-emitting elements (LED chips) adhere to each other without leaving air bubbles and without leaving gaps. On the other hand, the photocurable adhesive layer (a) after curing exhibits excellent processability. Therefore, when the laminate including the cured photocurable adhesive layer (a) is cut, the occurrence of glue shortage can be suppressed, and the occurrence of overflow and sagging of the adhesive layer from the end portion can be suppressed during storage. In this way, the photocurable adhesive layer (a) composed of the cured product of the adhesive composition (a) can suitably achieve both excellent level difference absorption properties and processability.
The method for producing the photocurable adhesive layer (a) is not particularly limited, and for example, the photocurable adhesive layer (a) can be produced by irradiating the adhesive composition (a) with an active energy ray, heating, drying, or the like. Specifically, there may be mentioned: the adhesive composition (a) is coated on a substrate or a release liner, and dried, cured, or dried and cured as necessary.
The coating (application) of the adhesive composition (a) may be performed by a known coating method. For example, coaters such as gravure roll coater, reverse roll coater, roll lick coater, dip roll coater, bar coater, knife coater, spray coater, comma coater, and direct coater can be used.
When the adhesive composition (a) is cured by irradiation with an active energy ray, it is preferable to carry out the curing in such a manner that the ethylenically unsaturated group contained in the adhesive composition (a) reacts and the benzophenone structure contained in the photocurable adhesive layer (a) remains. The active energy ray for forming the photocurable adhesive layer (a) is preferably ultraviolet light, and more preferably ultraviolet light containing no or little components having a wavelength of less than 300 nm.
When the adhesive composition (a) contains the BP polymer (a) and the ethylenically unsaturated compound (B), the photocurable adhesive layer (a) may contain the BP polymer (a) and the polymer (E) derived from the ethylenically unsaturated compound (B). In this embodiment, the adhesive composition (a) may be a composition in which the above-mentioned ethylenically unsaturated compound (B) does not contain an ethylenically unsaturated BP. According to the adhesive composition (a) of such a composition, a photocurable adhesive layer (a) comprising the BP polymer (a) and the polymer (E) derived from the ethylenically unsaturated compound (B), the above-mentioned polymer (E) being a polymer having no benzophenone structure (sometimes referred to as "non-BP polymer") can be produced.
On the other hand, when the adhesive composition (a) contains a mixture of monomer components constituting the BP polymer (a) or a partial polymer of the mixture of monomer components, the photocurable adhesive layer (a) may be a photocurable adhesive layer containing 2 or more polymers having different monomer compositions, and at least 1 of the 2 or more polymers may be a polymer having a benzophenone structure in a side chain (sometimes referred to as "BP polymer (a')"). The photocurable adhesive layer may contain only 2 or more BP polymers (a ') as the 2 or more polymers, or may contain a non-BP polymer and a BP polymer (a') in combination. The non-BP polymer may be formed by using an adhesive composition comprising an ethylenically unsaturated compound having no benzophenone structure and polymerizing the ethylenically unsaturated compound. The BP polymer (a') may be, for example, the BP polymer (a) contained in the pressure-sensitive adhesive composition (a), a modified product thereof, or a product obtained by copolymerizing an ethylenically unsaturated BP contained in the pressure-sensitive adhesive composition (a) with another ethylenically unsaturated compound.
The 2 or more polymers may be chemically bonded or not bonded. Some forms of the photocurable adhesive layer (a) may include at least 1 BP polymer in a form that is not chemically bonded to a polymer other than the BP polymer.
The irradiation with active energy rays for curing the adhesive composition (a) is preferably carried out in such a manner that ethylenically unsaturated groups are reacted and a benzophenone structure is left. As the above-mentioned adhesive composition (a), an adhesive composition comprising a BP polymer (a) and an ethylenically unsaturated compound (B) can be preferably used. As the light source for curing the adhesive composition (A) to form the photo-crosslinkable adhesive, a light source capable of irradiating ultraviolet rays containing no component having a wavelength of less than 300nm or containing a small amount of the component having the wavelength, such as the above-mentioned black light lamp or UV-LED lamp, is preferably used.
In a preferred embodiment of the present invention, the maximum value of the transmittance at a wavelength of 200 to 400nm (preferably, 330 to 400 nm) of the photocurable adhesive layer (a) is larger than the maximum value of the transmittance at a wavelength of 400 to 700 nm. The photocurable adhesive layer (a) having excellent light-shielding properties against visible light seals a fine level difference between a metal wiring layer of a self-luminous display device (mini/micro LED display device) and a light-emitting element (LED chip) without a gap, thereby preventing reflection due to metal wiring or the like, preventing color mixing of the light-emitting element (LED chip), and improving the contrast of an image. On the other hand, the photocurable adhesive layer (a) having a high transmittance in the ultraviolet region (wavelength of 200 to 400nm, preferably 330 to 400 nm) is cured by irradiating ultraviolet rays to form a cross-linked benzophenone structure, thereby improving the workability and suppressing the occurrence of gel shortage during cutting and the occurrence of overflow and sagging of the adhesive layer from the end during storage.
In a preferred embodiment of the present invention, the maximum value of the transmittance at a wavelength of 400 to 700nm (visible light region) of the photocurable adhesive layer (a) is, for example, 80% or less, or 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.
In a preferred embodiment of the present invention, the average transmittance at a wavelength of 200 to 400nm (preferably, 330 to 400 nm) of the photocurable adhesive layer (a) is larger than the average transmittance at a wavelength of 400 to 700 nm. The average transmittance of the photocurable adhesive layer (a) at a wavelength of 400 to 700nm (visible light region) is, for example, 80% or less, or 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.
The photocurable adhesive layer (a) preferably contains, for example, about 0.1mg or more of benzophenone structure per 1g of the adhesive layer in terms of 4-benzoylphenyl acrylate. Hereinafter, the weight of the benzophenone-structured 4-benzoylphenyl acrylate contained in 1g of the photocurable adhesive layer (A) in terms of weight is sometimes referred to as BP equivalent (unit: mg/g) of the adhesive layer. From the viewpoint of obtaining a higher photocuring effect (for example, an effect of improving processability by photocuring), the BP equivalent weight of the pressure-sensitive adhesive layer is usually suitably 0.3mg/g or more, and may be 0.5mg/g or more, 1mg/g or more, 5mg/g or more, 10mg/g or more, or 20mg/g or more. From the viewpoint of impact resistance of the joined portion formed from the photocurable material and suppression of strain in the photocurable material, the BP equivalent weight of the pressure-sensitive adhesive layer is usually preferably 100mg/g or less, and may be 80mg/g or less, 60mg/g or less, 40mg/g or less, 25mg/g or less, or 15mg/g or less.
(storage modulus)
The storage modulus (G' b 85) at 85 ℃ of the photocurable adhesive layer (A) before curing is not particularly limited, but is, for example, preferably less than 65kPa, more preferably 60kPa or less, still more preferably 55kPa or less, particularly preferably 50kPa or less, and further may be 45kPa or less. Such a configuration is preferable for achieving excellent level difference absorption of the photocurable adhesive layer (a) before curing. The G' b85 is not particularly limited, but is, for example, preferably 5kPa or more, more preferably 10kPa or more, and still more preferably 15kPa or more, from the viewpoint of handling properties and workability. The storage modulus (G' B85) at 85 ℃ of the photocurable adhesive layer (A) before curing can be adjusted by the composition of the adhesive composition (A) (e.g., mw, tg of the BP polymer (A; weight fraction of the BP polymer (A); the composition of the monomer components constituting the BP polymer (A) and the ethylenically unsaturated compound (B), the kind and amount of the functional group; the kind and amount of the crosslinking agent), and the like.
The storage modulus (G' a 10) at 10 ℃ of the photocurable adhesive layer (a) after curing is not particularly limited, but is, for example, preferably 90kPa or more, more preferably 100kPa or more, more preferably 110kPa or more, more preferably 120kPa or more, more preferably 130kPa or more, more preferably greater than 146kPa, more preferably 180kPa or more, further preferably 200kPa or more, particularly preferably 250kPa or more, and further may be 300kPa or more, or 350kPa or more. Such a configuration is preferable for achieving excellent processability of the photocurable adhesive layer (a) after curing. The G' a10 is not particularly limited, but is, for example, 5000kPa or less, preferably 2500kPa or less, and more preferably 1000kPa or less, from the viewpoint of adhesion reliability. The storage modulus (G' a 10) at 10 ℃ of the photocurable adhesive layer (A) after curing can be adjusted by the composition of the adhesive composition (A) (e.g., mw, tg, BP equivalent of the BP polymer (A); weight fraction of the BP polymer (A); composition of the monomer components constituting the BP polymer (A) and the ethylenically unsaturated compound (B), kind and amount of functional group; kind and amount of crosslinking agent), and the like.
The ratio (G 'a10/G' b 85) of the storage modulus (G 'a 10) at 10 ℃ of the photocurable adhesive layer (a) after curing to the storage modulus (G' b 85) at 85 ℃ of the photocurable adhesive layer (a) before curing is not particularly limited, and is, for example, preferably greater than 2.8, more preferably 2.9 or more, further preferably 3 or more, particularly preferably 3.1 or more, and further may be 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, 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 view of being able to achieve both of excellent level difference absorption of the photocurable adhesive layer (a) before curing and excellent processability of the photocurable 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, and even more preferably 30 or less, from the viewpoint of handling property, and adhesion reliability, for example. The ratio (G 'a10/G' B85) of the storage modulus (G 'a 10) at 10 ℃ of the photocurable adhesive layer (A) after curing to the storage modulus (G' B85) at 85 ℃ of the photocurable adhesive layer (A) before curing can be adjusted by the composition of the adhesive composition (A) (for example, tg, mw, BP equivalent of the BP polymer (A; weight fraction of the BP polymer (A); composition and kind and amount of functional group of monomer components constituting the BP polymer (A) and the ethylenically unsaturated compound (B); kind and amount of crosslinking agent) and the like.
The storage modulus (G' b 10) at 10 ℃ of the photocurable adhesive layer (a) before curing is not particularly limited, but is, for example, preferably 10kPa or more, more preferably 50kPa or more, further preferably 70kPa or more, or may be 90kPa or more and 100kPa or more, from the viewpoint of handling properties and workability. The G' b10 is not particularly limited, but is, for example, 5000kPa or less, preferably 2500kPa or less, and more preferably 1000kPa or less, from the viewpoint of adhesion reliability. The storage modulus (G' B10) at 10 ℃ of the photocurable adhesive layer (A) before curing can be adjusted by the composition of the adhesive composition (A) (e.g., mw, tg of the BP polymer (A; weight fraction of the BP polymer (A); the composition of the monomer components constituting the BP polymer (A) and the ethylenically unsaturated compound (B), the kind and amount of the functional group; the kind and amount of the crosslinking agent), and the like.
The storage modulus (G' a 85) at 85 ℃ of the photocurable adhesive layer (a) after curing is not particularly limited, but is, for example, preferably 10kPa or more, preferably 20kPa or more, and more preferably 30kPa or more, from the viewpoint of handling properties and workability. The G' a85 is not particularly limited, but is, for example, 1000kPa or less, preferably 500kPa or less, and more preferably 200kPa or less, from the viewpoint of adhesion reliability. The storage modulus (G' a 85) at 85 ℃ of the photocurable adhesive layer (A) after curing can be adjusted by the composition of the adhesive composition (A) (e.g., mw, tg, BP equivalent of the BP polymer (A); weight fraction of the BP polymer (A); composition of the monomer components constituting the BP polymer (A) and the ethylenically unsaturated compound (B), kind and amount of functional group; kind and amount of crosslinking agent), and the like.
The storage modulus (G' a 25) at 25 ℃ of the photocurable adhesive layer (A) after curing is not particularly limited, but is preferably 70kPa or more, more preferably more than 100kPa, more preferably 150kPa or more, and further preferably 170kPa or more, for example. Such a configuration is preferable for achieving excellent processability of the photocurable adhesive layer (a) after curing. The G' a25 is not particularly limited, but is, for example, 5000kPa or less, preferably 2500kPa or less, and more preferably 1000kPa or less, from the viewpoint of adhesion reliability. The storage modulus (G' a 25) at 25 ℃ of the photocurable adhesive layer (A) after curing can be adjusted by the composition of the adhesive composition (A) (e.g., mw, tg, BP equivalent of the BP polymer (A); weight fraction of the BP polymer (A); composition of the monomer components constituting the BP polymer (A) and the ethylenically unsaturated compound (B), kind and amount of functional group; kind and amount of crosslinking agent), and the like.
The storage modulus (G' b 25) at 25 ℃ of the photocurable adhesive layer (A) before curing is not particularly limited, but is, for example, 300kPa or less, preferably 250kPa or less, and more preferably 200kPa or less. Such a configuration is preferable for achieving excellent level difference absorption of the photocurable adhesive layer (a) before curing. In addition, G' b25 is not particularly limited, and is, for example, preferably 10kPa or more, more preferably 30kPa or more, and still more preferably 50kPa or more, from the viewpoint of adhesion reliability. The storage modulus (G' B25) at 25 ℃ of the photocurable adhesive layer (A) before curing can be adjusted by the composition of the adhesive composition (A) (e.g., mw, tg of the BP polymer (A; weight fraction of the BP polymer (A); the composition of the monomer components constituting the BP polymer (A) and the ethylenically unsaturated compound (B), the kind and amount of the functional group; the kind and amount of the crosslinking agent), and the like.
The ratio (G ' a25/G ' b 85) of the storage modulus (G ' a 25) at 25 ℃ of the cured adhesive layer a to the storage modulus (G ' b 85) at 85 ℃ of the photocurable adhesive layer (a) before curing (G ' a) is not particularly limited, and is, for example, preferably 0.3 or more, more preferably 0.5 or more, more preferably 1 or more, more preferably more than 3, preferably 3.5 or more, and more preferably 4 or more. Such a configuration is preferable in view of being able to achieve both of excellent level difference absorbability of the pressure-sensitive adhesive layer a before curing and excellent processability of the pressure-sensitive adhesive layer a after curing. The ratio G 'a25/G' b85 is not particularly limited, and is, for example, 100 or less, preferably 50 or less, and more preferably 30 or less from the viewpoint of handling property, workability, and adhesion reliability. The ratio (G 'a25/G' B85) of the storage modulus (G 'a 25) at 25 ℃ of the cured adhesive layer A to the storage modulus (G' B85) at 85 ℃ of the photocurable adhesive layer (A) before curing (G 'a25/G' B85) can be adjusted by the composition of the adhesive composition (A) (e.g., mw, tg, BP equivalent of the BP polymer (A; weight fraction of the BP polymer (A); composition of the monomer components constituting the BP polymer (A) and the ethylenically unsaturated compound (B), kind and amount of the functional group; kind and amount of the crosslinking agent), etc.
The curing conditions in the "photocurable adhesive layer (a) after curing" are not particularly limited, and the adhesive layer (a) is preferably ultraviolet rays that exhibit transparency. More preferably, ultraviolet rays having a wavelength of 200 to 400nm, and still more preferably having a wavelength of less than 300 nm. As the light source for ultraviolet irradiation, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, a microwave excitation type lamp, a metal halide lamp, a chemical lamp, a black light lamp, or an LED can be used. The irradiation energy, irradiation time, and irradiation method of the curing radiation can be appropriately set as long as the photocurable pressure-sensitive adhesive layer (a) can be cured without adversely affecting the adherend. For example, when ultraviolet rays are used as the curing radiation, the irradiation dose (cumulative light dose) is preferably 1000mJ/cm 2 ～10000mJ/cm 2 More preferably 2000mJ/cm 2 ～4000mJ/cm 2 More preferably 3000mJ/cm 2 。
The storage modulus is a value measured by dynamic viscoelasticity measurement.
[ VOC emission amount ]
The VOC (volatile organic compound) emission amount of the photocurable adhesive layer (a) is not particularly limited. The VOC emission may be, for example, 5000. Mu.g/g or less, 3000. Mu.g/g or less, or 1000. Mu.g/g or less. In some embodiments, the VOC emission amount of the photocurable adhesive layer (A) is preferably 500. Mu.g/g or less, more preferably 300. Mu.g/g or less, and still more preferably 100. Mu.g/g or less. The photocurable adhesive layer (a) having a small VOC emission amount is low in odor and is preferable from the viewpoint of environmental hygiene. A small amount of VOC emission from the photocurable adhesive layer (a) is also preferable from the viewpoint of suppressing foaming due to Volatile Organic Compounds (VOC) in the photocurable adhesive layer (a) and reducing contamination. The VOC emission amount of the photocurable adhesive layer (a) is measured by the following method using an appropriate amount (for example, about 1mg to 2 mg) of the photocurable adhesive layer (a) as a measurement sample. The thickness of the measurement sample is preferably 1mm or less.
[ VOC measurement test ]
The assay sample was placed in a 20mL vial and capped tightly. Next, the vial was heated at 80 ℃ for 30 minutes, and 1.0mL (sample gas) of the heated gas was injected into a Gas Chromatography (GC) measuring apparatus using a headspace autosampler (HSS). Based on the obtained gas chromatogram, the amount of gas generated from the measurement sample was obtained in the form of n-decane conversion. From the obtained values, the emission amount of VOC (. Mu.g/g) per 1g of the measurement sample was determined. The amount of n-decane conversion was determined by using a previously prepared standard curve of n-decane, taking the detection intensity of produced gas obtained from GC Mass as the detection intensity of n-decane. The settings of HSS and GC are as follows.
HSS: model "7694" made by Agilent Technologies Inc "
Heating time: 30 minutes
Pressurizing time: 0.12 minute
Ring filling time: 0.12 minute
Ring balance time: 0.05 minute
Injection time: 3 minutes
Sample loop temperature: 160 deg.C
Temperature of the conveying line: 200 deg.C
A GC device: model number "6890" made by Agilent Technologies "
Column: the trade name of the capillary column J & W manufactured by GL Science corporation is "DB-ffaP" (inner diameter 0.533 mm. Times. Length 30m, film thickness 1.0 μm)
Column temperature: 250 deg.C (10 deg.C/min from 40 deg.C to 90 deg.C, then 20 deg.C/min to 250 deg.C, holding for 5 min)
Column pressure: 24.3kPa (constant current mode)
Carrier gas: helium (5.0 mL/min)
Filling port: split flow (split ratio 12
Injection port temperature: 250 deg.C
A detector: FID
Detector temperature: 250 ℃ C
In general, as volatile organic compounds that can be factors for increasing the VOC emission amount of the binder, there can be mentioned organic solvents (for example, residues of organic solvents contained in the binder composition (a)), unreacted materials of ethylenically unsaturated compounds contained in the binder composition (for example, unpolymerized acrylic monomers, hereinafter referred to as "residual monomers"), and the like. The photocurable adhesive layer (a) can suppress the content of such organic solvent and residual monomer to a level that satisfies any of the above VOC emission amounts. The photocurable adhesive layer (a) has such a constitution that the amount of residual monomers is limited, and a new crosslink can be formed in the system by utilizing the benzophenone structure of the BP polymer (a), whereby a photocurable material having improved processability can be formed.
The lower the VOC emission amount of the photocurable adhesive layer (a) disclosed herein is in principle, the more preferable, but from the practical viewpoint of productivity, cost, and the like, in some embodiments, the VOC emission amount may be, for example, 10 μ g/g or more, 30 μ g/g or more, 80 μ g/g or more, 150 μ g/g or more, or 200 μ g/g or more.
The VOC emission amount of the photocurable adhesive layer (a) can be adjusted by the composition of the adhesive composition (a) (for example, the composition of the monomer components constituting the BP polymer (a) and the ethylenically unsaturated compound (B), the amount of the organic solvent), the curing conditions (heating conditions, ultraviolet irradiation conditions) of the adhesive composition (a), and the like.
(gel fraction)
The gel fraction of the photocurable adhesive layer (a) is not particularly limited, but is usually preferably 5% or more, preferably 15% or more, and may be 25% or more, and may be 35% or more, from the viewpoints of the cohesiveness of the photocurable adhesive layer (a), the handling properties of an adhesive sheet having the photocurable adhesive layer (a), and the like. The gel fraction of the photocurable adhesive layer (a) is 100% or less in principle. From the viewpoint of the level difference absorption property with respect to the surface shape of an adherend, the gel fraction of the photocurable pressure-sensitive adhesive layer (a) is preferably less than 85%, may be less than 70%, may be less than 55%, or may be less than 40%.
The gel fraction was measured by the following method. That is, about 0.5g of the measurement sample was accurately weighed and the weight thereof was set to W1. The measurement sample was wrapped in a porous PTFE (polytetrafluoroethylene) sheet, immersed in ethyl acetate at room temperature for 1 week, dried, and the weight W2 of the ethyl acetate-insoluble component was measured, and the gel fraction was calculated by substituting W1 and W2 into the following formula.
Gel fraction (%) = W2/W1 × 100;
as the porous PTFE sheet, a product name "NITOFLON NTF1122" manufactured by ritong electrical corporation or a product equivalent thereof can be used.
In some embodiments of the photocurable adhesive layer (A), the photocurable adhesive layer (A) is irradiated with a high-pressure mercury lamp at an illuminance of 300mW/cm 2 And a cumulative light amount of 10000mJ/cm 2 The gel fraction of the photo-cured product obtained by irradiating the photo-cured product with ultraviolet light under the conditions (1) may be, for example, 70% or more, preferably 90% or more, 95% or more, or 98% or more. The gel fraction of the photo-cured product is 100% or less in principle. The gel fraction was measured in the same manner as described above.
The gel fraction of the photocurable adhesive layer (a) can be adjusted by the composition of the adhesive composition (a) (e.g., mw, tg, BP equivalent of the BP polymer (a); the weight fraction of the BP polymer (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 crosslinking agent), the curing conditions (heating conditions, ultraviolet irradiation conditions) of the adhesive composition (a) and the photocurable adhesive layer (a), and the like.
The glass transition temperature (Tg) of the photocurable adhesive layer (A) is not particularly limited, but is preferably-60 to 20 ℃, more preferably-40 to 10 ℃, and still more preferably-30 to 0 ℃. When the Tg is higher than 20 ℃, the adhesive force at room temperature cannot be developed.
The Tg is not particularly limited, and can be measured, for example, by Differential Scanning Calorimetry (DSC) using the pressure-sensitive adhesive layer as a sample for measurement in accordance with JIS K7121. Specifically, the measurement can be carried out, for example, using a measuring apparatus having the apparatus name "Q-2000" manufactured by TA instruments under the conditions of-80 ℃ to 80 ℃ and a temperature rise rate of 10 ℃/min.
The thickness of the photocurable adhesive layer (a) is not particularly limited, and may be appropriately set so that light-emitting elements arranged on a display panel, which will be described later, can be sufficiently sealed. For example, the thickness of the photocurable adhesive layer (a) is adjusted to be 1.0 to 4.0 times, preferably 1.1 to 3.0 times, more preferably 1.2 to 2.5 times, and still more preferably 1.3 to 2.0 times the height of the light-emitting element. When the thickness is 1.0 times or more, the photocurable adhesive layer (a) easily follows the level difference, and the level difference absorption property is improved. Further, by setting the thickness to 4.0 or less, the photocurable adhesive layer (a) is less likely to be deformed, and the workability is improved.
The thickness of the photocurable adhesive layer (A) may be, for example, about 10 to 500. Mu.m, or 20 μm or more, 30 μm or more, 40 μm or more, or 50 μm or more. The thickness of the photocurable adhesive layer (A) may be 400 μm or less, 300 μm or less, 250 μm or less, or 200 μm or less. When the thickness is 10 μm or more, the photocurable adhesive layer (a) easily follows the level difference portion, and the level difference absorption property is improved. Further, by setting the thickness to 500 μm or less, the photocurable 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 photocurable pressure-sensitive adhesive layer (a), reflection and gloss on the metal surface can be prevented. The reflectance in the visible light region of 5 ° regular reflection when a metal adherend is laminated on the photocurable pressure-sensitive adhesive layer (a) is preferably 50% or less, more preferably 30% or less, still more preferably 15% or less, and particularly preferably 10% or less. The gloss (based on JIS Z8741-1997) when a metal adherend is laminated on the photocurable pressure-sensitive adhesive layer (a) is preferably 100% or less, more preferably 80% or less, further preferably 60% or less, and particularly preferably 50% or less.
As the metal adherend, copper, aluminum, stainless steel, or the like can be used.
[ formation of photo-cured product ]
The photocurable adhesive layer (a) can be photocrosslinked by, for example, irradiating ultraviolet rays containing a wavelength component that can excite a benzophenone structure. It is preferable to use a light source that can irradiate ultraviolet rays containing components having a wavelength of less than 300 nm. Examples of the light source include, but are not limited to, a high-pressure mercury lamp, a low-pressure mercury lamp, a metal halide lamp, and a super UV lamp. The light irradiated from the light source may contain a component having a wavelength of 300nm or more.
Examples of the light source capable of irradiating ultraviolet rays not containing or containing a wavelength component capable of exciting a benzophenone structure (for example, a component having a wavelength of less than 300 nm) include a black light lamp and a UV-LED lamp. These light sources can be preferably employed as a light source for advancing the reaction (polymerization reaction or curing reaction) of the ethylenically unsaturated group by light irradiation conducted in the presence of the benzophenone structure. In the ultraviolet irradiation for reacting an ethylenically unsaturated group, the photopolymerization initiator (C) can be used to accelerate the reaction.
The photocurable adhesive layer (a) may be a composition that does not substantially contain a photopolymerization initiator that generates radicals by absorbing light having a wavelength of 300nm or more, and for example, may be a composition that does not substantially contain a photopolymerization initiator that generates radicals by absorbing visible light having a wavelength of 380nm or more (particularly, 400nm or more). This may be advantageous from the viewpoint of optical characteristics of the photocurable adhesive layer (a). The photopolymerization initiator which does not contain a radical generating substance by absorbing light having a wavelength of 300nm or more means the photopolymerization initiator which does not contain a form capable of generating the radical (a form having a site cleaved by the light), and a cleavage residue of the photopolymerization initiator may be allowed to be contained. In a preferred embodiment, the photocurable adhesive layer (a) does not substantially contain a photopolymerization initiator containing a phosphorus element in its molecule. The photocurable adhesive layer (a) disclosed herein may be substantially free of any of a photopolymerization initiator containing a phosphorus element in its molecule and a cleavage residue of the photopolymerization initiator.
[ Photocurable adhesive sheet (A) ]
The photocurable adhesive sheet (a) has a photocurable adhesive layer (a).
The form of the photocurable pressure-sensitive adhesive sheet (a) is not particularly limited as long as it has a pressure-sensitive adhesive surface formed on the surface of the photocurable pressure-sensitive adhesive layer (a). The photocurable adhesive sheet (a) may be a single-sided adhesive sheet having only one side as an adhesive side, or may be a double-sided adhesive sheet having both sides as adhesive sides. In the case where the photocurable adhesive sheet a is a double-sided adhesive sheet, the photocurable adhesive sheet (a) may have a form in which both adhesive surfaces are provided by the photocurable adhesive layer (a), or may have a form in which 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). From the viewpoint of bonding adherends to each other, a double-sided pressure-sensitive adhesive sheet is preferred, and 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) is more preferred.
The photocurable pressure-sensitive adhesive sheet (a) may be a pressure-sensitive adhesive sheet without a substrate (base layer), that is, a so-called "substrate-free type" pressure-sensitive adhesive sheet (sometimes referred to as "substrate-free pressure-sensitive adhesive sheet") or a pressure-sensitive adhesive sheet with a substrate (sometimes referred to as "substrate-attached pressure-sensitive adhesive sheet"). Examples of the substrate-free pressure-sensitive adhesive sheet in the present invention include: a double-sided adhesive sheet composed only of the photocurable adhesive layer (a), and a double-sided adhesive sheet formed of the photocurable adhesive layer (a) and other adhesive layers (adhesive layers other than the photocurable adhesive layer (a)). Examples of the substrate-attached pressure-sensitive adhesive sheet of the present invention include: a single-sided pressure-sensitive adhesive sheet having a photocurable pressure-sensitive adhesive layer (a) on one side of a substrate, a double-sided pressure-sensitive adhesive sheet having a photocurable pressure-sensitive adhesive layer (a) on both sides of a substrate, and a double-sided pressure-sensitive adhesive sheet having a photocurable pressure-sensitive adhesive layer (a) on one side of a substrate and another pressure-sensitive adhesive layer on the other side.
Among the above, from the viewpoint of improving optical properties such as transparency, a substrate-less pressure-sensitive adhesive sheet is preferable, and a double-sided pressure-sensitive adhesive sheet (substrate-less double-sided pressure-sensitive adhesive sheet) having no substrate and composed of only the photocurable pressure-sensitive adhesive layer (a) is more preferable. In addition, when the photocurable adhesive sheet (a) is an adhesive sheet having a substrate, from the viewpoint of processability, a double-sided adhesive sheet (substrate-attached double-sided adhesive sheet) having a photocurable adhesive layer (a) on both sides of the substrate is preferable, though not particularly limited.
The "substrate (base layer)" refers to a portion to be bonded to an adherend (optical member or the like) together with the pressure-sensitive adhesive layer when the photocurable pressure-sensitive adhesive layer (a) is used for (bonded to) the adherend, and does not include a release film (separator) that is peeled off when the pressure-sensitive adhesive sheet is used (bonded).
The photocurable adhesive sheet a may be a substrate-attached adhesive sheet as described above. Examples of such a substrate include various optical films such as a plastic film, an anti-reflection (AR) film, a polarizing plate, and a retardation plate. Examples of the material of the plastic film and the like include plastic materials such as polyester resins such as polyethylene terephthalate (PET), acrylic resins such as polymethyl methacrylate (PMMA), polycarbonate, triacetyl cellulose (TAC), polysulfone, polyarylate, polyimide, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, ethylene-propylene copolymers, cyclic olefin polymers such as "Arton" (a cyclic olefin polymer, manufactured by JSR corporation) and "ZEONOR" (a cyclic olefin polymer, manufactured by japan patent Weng Zhushi) and the like. These plastic materials may be used alone or in combination of 2 or more.
The substrate is preferably transparent. The total light transmittance of the substrate in the visible light wavelength region (according to JIS K7361-1) is not particularly limited, but is preferably 85% or more, and more preferably 88% or more. The haze (according to JIS K7136) of the substrate is not particularly limited, but is preferably 1.5% or less, and more preferably 1.0% or less. Examples of such transparent substrates include PET films and non-oriented films such as "Arton" trade name and "ZEONOR" trade name.
The thickness of the substrate is not particularly limited, but is preferably 12 to 75 μm. The substrate may have any form of a single layer or a plurality of layers. The surface of the substrate may be appropriately subjected to known and conventional surface treatments such as 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.
The photocurable adhesive sheet (a) may have another adhesive layer (an adhesive layer other than the adhesive layer a) as described above. The other pressure-sensitive adhesive layer is not particularly limited, and examples thereof include pressure-sensitive adhesive layers formed of known and conventional pressure-sensitive adhesives such as urethane-based pressure-sensitive adhesives, acrylic-based pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, polyester-based pressure-sensitive adhesives, polyamide-based pressure-sensitive adhesives, epoxy-based pressure-sensitive adhesives, vinyl alkyl ether-based pressure-sensitive adhesives, and fluorine-based pressure-sensitive adhesives. The above-mentioned binders may be used singly or in combination of 2 or more.
The photocurable pressure-sensitive adhesive sheet (a) may have other layers (for example, an intermediate layer, an undercoat layer, and the like) in addition to the photocurable pressure-sensitive adhesive layer (a), the substrate, and the other pressure-sensitive adhesive layer, within a range in which the effects of the present invention are not impaired.
The photocurable pressure-sensitive adhesive sheet (a) may be used by providing a release film (separator) on the pressure-sensitive adhesive surface until the time of use. The form in which the pressure-sensitive adhesive surface of the photocurable pressure-sensitive adhesive sheet (a) is protected by the release film is not particularly limited, and may be a form in which each pressure-sensitive adhesive surface is protected by 2 sheets of release film, or a form in which each pressure-sensitive adhesive surface is protected by 1 sheet of release film whose both surfaces are release surfaces by winding up in a roll. The release film is used as a protective material for the pressure-sensitive adhesive layer and is released when attached to an adherend. In the photocurable pressure-sensitive adhesive sheet (a), the release film also functions as a support for the pressure-sensitive adhesive layer. The release film need not be provided.
The thickness (total thickness) of the photocurable pressure-sensitive adhesive sheet (a) is not particularly limited, but is preferably 10 μm to 1mm, more preferably 100 to 500 μm, and still more preferably 150 to 350 μm. When the thickness is 10 μm or more, the photocurable adhesive layer (a) can easily follow the level difference portion, and the level difference absorbability can be improved. The thickness of the photocurable adhesive sheet (a) does not include the thickness of the release film.
The photocurable adhesive sheet (a) contains the photocurable adhesive layer (a) described above, and therefore has light absorption properties with respect to visible light. The photocurable adhesive sheet (a) may have a total light transmittance of, for example, 80% or less, or 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.
The photocurable adhesive sheet (a) has excellent level difference absorption before curing because it has the photocurable adhesive layer (a). For example, the level difference absorbability is excellent for a high level difference exceeding 40 μm in addition to a level difference of 5 to 10 μm. Further, the film also has a level difference absorbability against a level difference exceeding 80 μm.
Further, since the photocurable adhesive sheet (a) has the photocurable adhesive layer (a), it has excellent workability after curing, and can suppress the occurrence of glue shortage during cutting and the occurrence of overflow and sagging of the adhesive layer from the edge during storage.
Further, since the photocurable adhesive sheet (a) has the photocurable adhesive layer (a), the adhesion reliability is also excellent.
Fig. 1 to 3 are views (sectional views) schematically showing one embodiment of a photocurable adhesive sheet (a) according to the present invention.
Fig. 1 shows an embodiment of a photocurable pressure-sensitive adhesive sheet (a). The photocurable adhesive sheet 1A is configured as a one-sided adhesive photocurable adhesive sheet, which includes: the photocurable pressure-sensitive adhesive layer 10 has one surface 10A serving as a bonding surface (pressure-sensitive adhesive surface) to an adherend, and the substrate S1 laminated on the other surface 10B of the photocurable pressure-sensitive adhesive layer 10. The photocurable adhesive layer 10 is bonded to the one surface S1A of the substrate S1. As the substrate S1, for example, a plastic film such as a polyester film can be used. The substrate S1 may be an optical film such as a polarizing plate or a cover member. In the embodiment shown in fig. 1, the photocurable adhesive layer 10 has a single-layer structure. As shown in fig. 1, for example, the psa sheet 1A before use (before application to an adherend) may be in the form of a psa sheet 50 with a release film, in which the psa surface 10A is protected by a release film S2 that forms a releasable surface (release surface) at least on the psa layer side. Alternatively, the second surface S1B (the surface opposite to the first surface S1A, also referred to as the back surface) of the substrate S1 may be a release surface, and the adhesive surface 10A may be protected by being wound or laminated so that the adhesive surface 10A abuts against the second surface S1B of the substrate S1.
The release film is not particularly limited, and examples thereof include a release film obtained by subjecting the surface of a film base such as a resin film or paper to a release treatment, and a release film formed of a low-adhesion material such as a fluorine-based polymer (polytetrafluoroethylene or the like) or a polyolefin-based resin (polyethylene, polypropylene or the like). For example, a silicone-based or long chain alkyl-based release agent can be used for the release treatment. In some embodiments, a resin film subjected to a peeling treatment may be preferably used as the peeling film.
The photocurable adhesive sheet (a) may be a substrate-less double-sided adhesive sheet comprising the photocurable adhesive layer (a). As shown in fig. 2, the substrate-less double-sided psa sheet 1B may be in a form in which the respective surfaces 10A, 10B of the psa layer 10 are protected before use by release films S3, S4 that form releasable surfaces (release surfaces) at least on the psa layer side. Alternatively, the back surface (the surface opposite to the pressure-sensitive adhesive side) of the release film S4 may be a release surface, and the pressure- sensitive adhesive surfaces 10A and 10B may be protected by winding or laminating the release film so that the pressure-sensitive adhesive surface 10B contacts the back surface of the release film S4. Such a substrate-free double-sided pressure-sensitive adhesive sheet can be used, for example, by bonding a substrate to any one surface of the pressure-sensitive adhesive layer.
The photocurable adhesive sheet (a) may be a component of an optical member with an adhesive sheet in which an optical member is bonded to one surface of an adhesive layer. For example, the photocurable adhesive sheet 1A shown in fig. 1 may be a component of an optical member with adhesive sheet 100 in which an optical member S5 is bonded to one surface 10A of an adhesive layer 10 as shown in fig. 3. 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 adhesive layer (a) constituting the photocurable adhesive sheet (a) may be a cured layer of the corresponding adhesive composition (a). For example, the photocurable adhesive layer (a) may be obtained by applying (for example, coating) the adhesive composition (a) to an appropriate surface and then curing the adhesive composition (a). The curing of the adhesive composition (a) may be preferably performed by irradiation with active energy rays. The active energy ray for forming the photocurable adhesive layer (a) is preferably ultraviolet ray, and more preferably ultraviolet ray containing no component having a wavelength of 300nm or less or containing a small amount of the component.
The adhesive composition (a) can be applied using a conventional coating machine such as a gravure roll coater, a reverse roll coater, a roll-lick coater, a dip roll coater, a bar coater, a knife coater, or a spray coater. In the photocurable adhesive sheet (a) having the form of a substrate, as a method for providing the photocurable adhesive layer (a) on the substrate, a direct method of forming the photocurable adhesive layer (a) by directly applying the adhesive composition (a) to the substrate may be used, or a transfer method of transferring the photocurable adhesive layer (a) formed on the release surface to the substrate may be used.
< self-luminous display device >
The self-luminous display device of the 5 th side of the present invention is a display device as follows: a large number of minute light-emitting elements are arranged on a wiring board, and visual information such as characters, images, and videos is directly displayed on a display screen by blinking of each light-emitting element by selectively emitting light from each light-emitting element by a light-emission control means connected thereto. Examples of the self-luminous display device include a mini/micro LED display device and an organic EL (electroluminescence) display device. The photocurable adhesive sheet a according to aspect 1 of the present invention is particularly suitable for use in the production of mini/micro LED display devices.
Fig. 4 is a schematic view (cross-sectional view) showing one embodiment of a self-light emitting display device (mini/micro LED display device) of the 5 th aspect of the present invention.
In fig. 4, the mini/micro LED display device 200A is composed of: a display panel in which a plurality of LED chips 23 are arranged on one surface of a substrate 21 via a metal wiring layer 22, an adhesive layer 20 laminated on the display panel and sealing the metal wiring layer 22 and the plurality of LED chips 23, and a cover member 24 laminated on an upper portion (image display side) of the adhesive layer 20. The covering member 24 is not particularly limited, and may be made of the same material as the above-described "base material".
In the mini/micro LED display device 200A of the present embodiment, a metal wiring layer 22 for transmitting a light emission control signal to each LED chip 23 is laminated on a substrate 21 of a display panel. The LED chips 23 emitting light of red (R), green (G), and blue (B) colors are alternately arranged on the substrate 21 of the display panel via the metal wiring layer 22. The metal wiring layer 22 is formed of a metal such as copper, and reflects light emitted from each LED chip 23 to reduce visibility of an image. Further, light emitted from each LED chip 23 of RGB colors 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 adhesive layer 20 is composed of a cured product of the photocurable adhesive layer (a) of the present invention. The adhesive layer 20 sufficiently follows the fine level difference between the LED chips 23, and is sealed without a gap.
The adhesive layer 20 has sufficient light-shielding properties in the visible light region. Since the minute level differences between the LED chips 23 are sealed by the adhesive layer 20 having high light-shielding properties without any gap, reflection by the metal wiring layer 22 can be prevented, color mixing between the LED chips 23 can be prevented, and contrast can be improved.
The pressure-sensitive adhesive layer 20 is a cured product of the photocurable pressure-sensitive adhesive layer (a), and therefore has excellent processability. Therefore, the mini/micro LED display device 200A of the present embodiment can be prevented from being short of glue during the cutting process and from protruding or hanging from the end of the adhesive layer 20 during storage.
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 includes a member (e.g., an appearance film, a decorative film, and a surface protection plate) that retains visibility of the display device and the input device and plays a role of decoration and protection.
The self-luminous display device (mini/micro LED display device) of the present embodiment is not particularly limited, and can be preferably manufactured by a method including the following steps.
(1) And a step of laminating the photocurable adhesive layer (A) of the photocurable adhesive sheet (A) on a display panel having a plurality of light-emitting elements arranged on one surface of a substrate, and sealing the light-emitting elements with the photocurable adhesive layer (A).
(2) And (c) curing the photocurable adhesive layer (a) by irradiating it with ultraviolet light.
Fig. 5 is a view schematically showing the steps of one embodiment of a method for manufacturing a self-luminous display device (mini/micro LED display device) according to the 5 th aspect of the present invention. In the present embodiment, as shown in fig. 5 (a), the photocurable adhesive sheet 1C according to side 4 of the present invention and a display panel in which a plurality of light-emitting elements (LED chips) 23 are arranged on one surface of a substrate 21 with a metal wiring layer 22 interposed therebetween are used.
In the present embodiment, the photocurable adhesive sheet 1C is composed of a photocurable adhesive layer 10 and a cover member 24. In the present embodiment, the photocurable adhesive sheet 1C has the covering member 24, but the covering member 24 may not be provided. The cover member 24 is not particularly limited, and may be formed of the same material as the "base material" or may be a release film (separator).
Next, as shown in fig. 5 (b), the main surface 10A of the cover member 24 is not laminated in the photocurable adhesive layer 10 in which the photocurable adhesive sheet 1C is laminated on the surface of the display panel on which the plurality of LED chips are arranged, and the LED chips 23 and the metal wiring layer 22 are sealed with the photocurable adhesive layer 10. The lamination can be performed by a known method, for example, under a heating and pressurizing condition using an autoclave. The photocurable adhesive layer 10 of the photocurable adhesive sheet 1C has high fluidity and exhibits excellent level difference absorption. Therefore, the photocurable adhesive layer 10 is sealed so as to fill the height difference between the metal wiring layer 22 and the plurality of LED chips 23 without a gap.
Next, as shown in fig. 5 (c), the photocurable adhesive layer 10 is irradiated with ultraviolet rays and cured. Upon irradiation with ultraviolet rays, the benzophenone structure contained in the photocurable adhesive layer 10 is excited, and a crosslinked structure is formed by a hydrogen radical abstraction reaction, and a curing reaction is started. The ultraviolet ray is not particularly limited as long as it excites the benzophenone structure to cure the photocurable adhesive layer 10, and is preferably an ultraviolet ray that allows the photocurable adhesive layer 10 to transmit. That is, since the photocurable adhesive layer 10 has high light-shielding properties against visible light and high transparency to ultraviolet light, the photocurable adhesive layer 10 can be cured by ultraviolet light. Fig. 5 (c) shows an embodiment in which the photocurable adhesive layer 10 is cured by irradiation with ultraviolet light U.
The ultraviolet ray preferably has a wavelength of 200 to 400nm, more preferably a wavelength of less than 300 nm.
As the light source for ultraviolet irradiation, for example, a high-pressure mercury lamp, a low-pressure mercury lamp, a microwave excitation type lamp, a metal halide lamp, a chemical lamp, a black light lamp, or an LED can be used. The irradiation time and irradiation method of the ultraviolet ray can be appropriately set as long as the photocurable adhesive layer 10 can be cured without adversely affecting the display panel and the photocurable adhesive layer 10 is cured to exhibit sufficient workability. For example, the dose of ultraviolet radiation (cumulative light amount) is preferably 1000mJ/cm 2 ～10000mJ/cm 2 More preferably 2000mJ/cm 2 ～4000mJ/cm 2 More preferably 3000mJ/cm 2 。
By curing the photocurable adhesive layer 10, as shown in fig. 5 (d), a self-luminous display device (mini/micro LED display device) 200B can be obtained. In fig. 5 (d), 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) according to the 5 th aspect of the present invention.
The adhesive layer 20 has improved workability, and can prevent the adhesive layer from running out and sagging from the end during cutting and storage. The pressure-sensitive adhesive layer 20 can suppress the generation of gas such as carbon dioxide gas due to heating of the display panel, prevent the generation of bubbles, and improve the adhesion reliability.
Examples
The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.
[ example 1]
(preparation of adhesive composition)
An acrylic copolymer having a benzophenone structure in a side chain (product name "acResin A260UV", manufactured by BASF Co., ltd., tg: -39 ℃ C., mw: 19X 10) was put in a separable flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas inlet 4 BP equivalent: 2 mg/g) 50 parts by weight, 26 parts by weight of Butyl Acrylate (BA), 8 parts by weight of N-vinyl-2-pyrrolidone (NVP), 16 parts by weight of isobornyl acrylate (IBXA) and 0.2 part by weight of a photopolymerization initiator (product of IGM registers, trade name "Omnirad 184") having an absorption peak at a wavelength of 300nm to 500nm were mixed to prepare an adhesive composition A.
(preparation of Black adhesive composition)
To 100 parts by weight of the above adhesive composition A, 0.5 part by weight of a 20% dispersion of a BLACK pigment ("9256 BLACK" manufactured by TOKUSHIKI) was added to prepare a BLACK adhesive composition B1.
(preparation of Photocurable adhesive sheet)
The black pressure-sensitive adhesive composition B1 prepared above was applied to the release surface of a release film R1 (MRF #38, manufactured by Mitsubishi resin corporation) having a thickness of 38 μm and having a release surface on one side of the polyester film, and the air was blocked by covering a release film R2 (MRE #38, manufactured by Mitsubishi resin corporation) having a release surface on one side of the polyester film. From one side of the laminate, a black light lamp (product name FL15BL, toshiba Co., ltd.) was used to irradiate at an illuminance of 5mW/cm 2 1300mJ/cm of accumulated light amount 2 The condition (2) is irradiated with ultraviolet rays. Thus, a photocurable adhesive having a thickness of about 100 μm as a cured product of the black adhesive composition B1 was obtained in the form of a substrate-less double-sided adhesive sheetAnd a photocurable adhesive sheet D1 having the adhesive layer C1 sandwiched between the release films R1 and R2.
The illuminance value of the black light lamp was measured by an industrial UV inspection apparatus (manufactured by TOPCON, trade name: UVR-T1, light receiving part model UD-T36) having a peak sensitivity wavelength of about 350 nm.
[ example 2]
A photocurable adhesive sheet D2 having a photocurable adhesive layer C2 of a thickness of about 100 μm sandwiched between release films R1 and R2 as a cured product of the BLACK adhesive composition B2 was obtained in the same manner as in example 1, except that 1 part by weight of a 20% dispersion of a BLACK pigment (9256 BLACK, manufactured by TOKUSHIKI) was added to 100 parts by weight of the adhesive composition a to prepare a BLACK adhesive composition B2.
[ example 3]
A photocurable adhesive sheet D3 having a photocurable adhesive layer C3 of a thickness of about 100 μm sandwiched between release films R1 and R2 as a cured product of the BLACK adhesive composition B3 was obtained in the same manner as in example 1, except that 2 parts by weight of a 20% dispersion of a BLACK pigment (9256 BLACK, manufactured by TOKUSHIKI) was added to 100 parts by weight of the adhesive composition a to prepare a BLACK adhesive composition B3.
[ example 4]
A photocurable adhesive sheet D4 having a photocurable adhesive layer C4 of a thickness of about 100 μm sandwiched between release films R1 and R2 as a cured product of the BLACK adhesive composition B4 was obtained in the same manner as in example 1, except that 4 parts by weight of a 20% dispersion of a BLACK pigment (9256 BLACK, manufactured by TOKUSHIKI) was added to 100 parts by weight of the adhesive composition a to prepare a BLACK adhesive composition B4.
Comparative example 1
A photocurable adhesive sheet D5 having a photocurable adhesive layer C5 of a thickness of about 100 μm sandwiched between release films R1 and R2 as a cured product of the adhesive composition a was obtained as a substrate-less double-sided adhesive sheet in the same manner as in example 1, except that no black pigment was added to 100 parts by weight of the adhesive composition a.
Comparative example 2
(preparation of prepolymer)
67 parts by weight of Butyl Acrylate (BA), 14 parts by weight of cyclohexyl acrylate (CHA), 19 parts by weight of 4-hydroxybutyl acrylate (4-HBA), 0.09 parts by weight of a photopolymerization initiator (product name "Irgacure 184" manufactured by BASF) and 0.09 parts by weight of a photopolymerization initiator (product name "Irgacure 651" manufactured by BASF) were put into a separable flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen gas inlet tube as monomer components, and then nitrogen gas was passed through the flask and nitrogen substitution was carried out for about 1 hour while stirring. Then, at 5mW/cm 2 UVA is irradiated for polymerization, and the reaction rate is adjusted to be 5-15%, so that an acrylic prepolymer solution is obtained.
(preparation of adhesive composition)
To the acrylic prepolymer solution a obtained above (the total amount of the prepolymer was taken as 100 parts by weight), 9 parts by weight of 2-hydroxyethyl acrylate (HEA), 8 parts by weight of 4-hydroxybutyl acrylate (4-HBA), 0.02 part by weight of dipentaerythritol hexaacrylate (trade name "KAYARAD DPHA" manufactured by shinkamura chemical) as a polyfunctional monomer, 0.35 part by weight of 3-glycidoxypropyltrimethoxysilane as a silane coupling agent, and 0.45 part by weight of a polymerization initiator (Irgacure 651 "manufactured by BASF corporation) were added to obtain an adhesive composition.
(preparation of Black adhesive composition)
To 100 parts by weight of the above adhesive composition, 5.8 parts by weight of a 20% dispersion of a BLACK pigment (9256 BLACK manufactured by TOKUSHIKI corporation) and 0.2 part by weight of an additional photopolymerization initiator (Irgacure 651 manufactured by BASF corporation) were added to obtain a BLACK adhesive composition.
(preparation of adhesive sheet)
The black pressure-sensitive adhesive composition prepared above was applied to the release surface of a release film R1 (MRF #38, manufactured by Mitsubishi resin Co., ltd.) having a thickness of 38 μm and having a release surface on one side of a polyester film, and the polyester film was covered on one side to be releasedThe off-plane release film R2 (MRE #38, mitsubishi resin) blocks air. From one side of the laminate, a black light lamp (product name FL15BL, toshiba Co., ltd.) was used to irradiate at an illuminance of 5mW/cm 2 1300mJ/cm of accumulated light amount 2 The condition (2) is ultraviolet ray irradiation. Thus, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer of about 50 μm thickness sandwiched between the release films R1 and R2 as a cured product of the black pressure-sensitive adhesive composition was obtained as a substrate-less double-sided pressure-sensitive adhesive sheet.
[ example 5]
(preparation of Black adhesive composition)
To 100 parts by weight of the pressure-sensitive adhesive composition prepared in comparative example 2 were added 4 parts by weight of a 20% dispersion of a BLACK pigment (9256 BLACK, manufactured by TOKUSHIKI) and 0.2 part by weight of an additional photopolymerization initiator (Irgacure 651, manufactured by BASF) and 1 part by weight of 4-acryloyloxybenzophenone, manufactured by Ark Pharm, to obtain a BLACK pressure-sensitive adhesive composition.
(preparation of photocurable adhesive sheet)
The black pressure-sensitive adhesive composition prepared above was applied to the release surface of a release film R1 (MRF #38, manufactured by mitsubishi resin corporation) having a thickness of 38 μm and having a release surface on one side of the polyester film, and the release film R2 (MRE #38, manufactured by mitsubishi resin corporation) having a release surface on one side of the polyester film was covered to block air. From one side of the laminate, a black light lamp (product name FL15BL, toshiba Co., ltd.) was used to irradiate at an illuminance of 5mW/cm 2 1300mJ/cm of accumulated light amount 2 The condition (2) is ultraviolet ray irradiation. Thus, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer of about 100 μm thickness sandwiched between the release films R1 and R2 was obtained as a cured product of the black pressure-sensitive adhesive composition in the form of a substrate-less double-sided pressure-sensitive adhesive sheet.
The illuminance value of the black light lamp was measured by an industrial UV inspection apparatus (manufactured by TOPCON, inc.: UVR-T1, light receiving part model UD-T36) having a peak sensitivity wavelength of about 350 nm.
[ example 6]
A photocurable adhesive sheet was produced in the same manner as in example 5, except that 2 parts of 4-acryloyloxybenzophenone was used.
(evaluation)
The adhesive sheets obtained in the above examples and comparative examples were used for the following evaluations. The evaluation method is shown below. The results are shown in Table 1.
[ evaluation of transmittance ]
The release film on one side was peeled from the adhesive sheet, and the alkali-free glass was bonded to the exposed surface. Then, the release film on the other side was peeled from the adhesive sheet to obtain a sample in which the adhesive sheet was bonded to an alkali-free glass plate.
The total light transmittance was measured by a haze meter (product name "HN-150" manufactured by Nikkiso K.K.) according to the method defined in JIS K7361.
[ evaluation of storage modulus ]
Evaluation was performed using ARES GII from TA Instruments.
The adhesive sheets laminated to a thickness of about 1mm were sandwiched between 8mm parallel plates, and the storage modulus G ' at 10 ℃, 25 ℃ and 85 ℃ measured at-50 ℃ to 100 ℃ at an initial strain of 1%, a frequency of 1Hz, and a temperature rise rate of 5 ℃/min was read as the storage modulus G ' (G ' b10, G ' b25, G ' b 85) before curing.
Regarding the storage modulus G' after curing, the cumulative light amount will be 3000mJ/cm 2 The pressure-sensitive adhesive sheet sandwiched between the release films was irradiated with a high-pressure mercury lamp to obtain a laminate having a thickness of about 1mm, and evaluated as storage modulus G '(G' a10, G 'a25, G' a 85) after curing in the same manner as described above.
The accumulated light amount was measured by an industrial UV inspection apparatus (manufactured by TOPCON, trade name: UVR-T1, light receiving part model UD-T36) having a peak sensitivity wavelength of about 350 nm.
The pressure-sensitive adhesive sheet of comparative example 2 did not exhibit photocurability, and therefore the storage modulus G' after curing was not evaluated.
[ evaluation of the following Properties for height Difference ]
(preparation of uneven adherend)
A laminate of a TAC film (thickness 60 μm) and an adhesive (thickness 20 μm) was adhered to a 45mm X50 mm glass plate, and then CO was used 2 Laser (wavelength)10.6 μm/laser diameter good μm), and linear etching was performed at a pitch of 150 μm in the longitudinal direction/225 μm in the transverse direction within a range of 10mm × 10mm at the center, thereby obtaining an adherend a in which a TAC film and an adhesive layer were processed into a lattice-like uneven shape.
The adherend a simulates an LED panel in which a plurality of LED films are arranged on a substrate.
(preparation of adhesive sheet)
The pressure-sensitive adhesive sheets prepared in examples 1 to 4 and comparative example 1 were laminated to 2 sheets to have a thickness of about 200 μm. The pressure-sensitive adhesive sheet produced in comparative example 2 was laminated by 5 sheets to have a thickness of about 250 μm. The release film on one side of these laminated adhesive sheets was peeled off, and a PET film having a thickness of 75 μm was laminated on the exposed side.
(vacuum bonding)
The pressure-sensitive adhesive surface exposed by peeling the release film on the other surface of the laminated pressure-sensitive adhesive sheet obtained above was bonded to the processed surface of the adherend a with a precision within a processing range in which the pressure-sensitive adhesive sheet could completely cover the adherend a using a vacuum bonding apparatus (SE 340aaH, manufactured by CRIMB Products corporation), and samples for evaluation formed of a PET film/laminated pressure-sensitive adhesive sheet/adherend a were obtained, respectively. Further, autoclave treatment (50 ℃ C./0.5 MPa for 60 minutes) was performed to achieve adhesion.
(evaluation of following-up to height)
In the evaluation sample, when the pressure-sensitive adhesive sheet can follow the pattern portion of the uneven shape, the processed portion of the adherend a is recognized as transparent and the portion which cannot be followed is recognized as white, and the area of the white portion is calculated by the fixed point camera imaging, and the level difference following property is evaluated.
Height difference following Property (%) = area of white portion at evaluation of 100- { []/[ area of white part before bonding =1cm 2 ]×100}
[ evaluation of processability ]
(preparation of laminate for evaluation of processability)
The release film of the laminated adhesive sheet produced in the evaluation of the level difference following property was peeled off and bonded to fr-4 substrate (thickness 1.2 mm) manufactured by MISUMI Corporation. Autoclave treatment (50 ℃/0.5 MPa)Conditions 15 minutes), examples 1 to 4 and comparative example 1, which showed photocurability, were irradiated with ultraviolet light. The irradiation conditions of the ultraviolet light were set to a high-pressure mercury lamp, and the cumulative light amount was 3000mJ/cm 2 . The cumulative light amount was measured by an industrial UV inspection apparatus (manufactured by TOPCON, trade name: UVR-T1, light receiving part model UD-T36) having a peak sensitivity wavelength of about 350 nm.
(processing)
The laminate for evaluation of processability obtained above was cut using DTF6450 manufactured by Disco corporation. The cutting conditions were blade type P1A861 (abrasive grain # 400), spindle 30krpm, speed 30mm/s, and cooling water 1L/min.
(evaluation of processability)
The cut end portion was observed from the laminated pressure-sensitive adhesive sheet side with a solid microscope, and the workability was evaluated by the amount of glue bleeding from the cut end portion. The evaluation criteria are as follows.
○：0～150μm
△：150～200μm
X: 200 μm or more
[ evaluation of reflectance ]
A black acrylic plate was laminated with aluminum foil adhered thereto. The release film on one side 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 laminated on the exposed surface. The other surfaces of these sheets were peeled off from the release film, and the exposed adhesive surface was laminated on the aluminum foil side of the above-mentioned sheet to obtain a sample. For the obtained sample, reflectance (%) in the visible light region of 5 ° regular reflection was measured with the PET film set to the light source side in spectrophotometer U4100 (manufactured by Hitachi High-Technologies Corporation).
[ Table 1]
Figure BDA0004096818070000601
Examples 1 to 6, which are photocurable adhesive sheets, show excellent level difference following properties (level difference absorption properties) and processability, and also show suppressed transmittance and reflectance, and when used as a sealing material for LED panels, excellent antireflection effects and improvement in 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 level difference following properties (level difference absorption properties) and processability, but has high transmittance and reflectance, and cannot expect improvement in antireflection effect and contrast when used as a sealing material for an LED panel. Comparative example 2, which is a pressure-sensitive adhesive sheet containing a colorant but not exhibiting photocurability, exhibited poor level difference following properties (level difference absorption properties), but had poor processability.
Variations of the present invention are noted below.
[ supplementary note 1] an adhesive composition comprising a colorant and a polymer (A) having a benzophenone structure in a side chain,
the adhesive composition has a maximum value of transmittance at a wavelength of 200 to 400nm which is greater than a maximum value of transmittance at a wavelength of 400 to 700 nm.
[ additional note 2] an adhesive composition comprising a colorant and a partial polymer which is a mixture of monomer components constituting a polymer (A) having a benzophenone structure in a side chain or a mixture of monomer components constituting a polymer (A) having a benzophenone structure in a side chain,
the adhesive composition has a maximum value of transmittance at a wavelength of 200 to 400nm which is greater than a maximum value of transmittance at a wavelength of 400 to 700 nm.
[ appendix 3] the adhesive composition according to appendix 1 or 2, wherein the colorant is a colorant having a maximum value of transmittance at a wavelength of 200 to 400nm that is greater than a maximum value of transmittance at a wavelength of 400 to 700 nm.
[ appendix 4] the adhesive composition according to any one of appendix 1 to 3, further comprising an ethylenically unsaturated compound (B).
[ appendix 5] the adhesive composition according to any one of appendix 1 to 4, further comprising a photopolymerization initiator (C) that absorbs ultraviolet light having a wavelength of 300nm to 500nm and generates radicals.
[ supplementary note 6] A photocurable adhesive layer comprising a cured product of the adhesive composition according to any one of supplementary notes 1 to 5,
the cured product is a cured product in which the benzophenone structure of the polymer (A) having a benzophenone structure in a side chain remains.
[ additional notes 7] the photocurable adhesive layer according to additional note 6, wherein the maximum value of transmittance at a wavelength of 200 to 400nm is greater than the maximum value of transmittance at a wavelength of 400 to 700 nm.
[ additional character 8] the photocurable adhesive layer according to additional character 6 or 7, wherein the storage modulus (G' b 85) at 85 ℃ of the photocurable adhesive layer before curing is less than 65kPa.
[ appendix 9] the photocurable adhesive layer according to any one of appendixes 6 to 8, wherein a storage modulus (G 'a 10) of the photocurable adhesive layer at 10 ℃ after curing and a storage modulus (G' b 85) of the photocurable adhesive layer at 85 ℃ before curing satisfy the following relational expression (1).
2.8<G'a10/G'b85 (1)
[ additional notes 10] the photocurable adhesive layer according to any one of the additional notes 6 to 9, wherein the storage modulus (G' a 10) at 10 ℃ of the photocurable adhesive layer after curing is 90kPa or more.
[ attached notes 11 ]]The photocurable adhesive layer according to any one of supplementary notes 6 to 10, wherein the curing is based on a wavelength of less than 300nm and a cumulative light amount of 3000mJ/cm 2 Curing by ultraviolet irradiation.
[ additional note 12] A photocurable adhesive sheet having the photocurable adhesive layer according to any one of additional notes 6 to 11.
[ additional note 13] a self-light-emitting display device, comprising:
display panel having a plurality of light-emitting elements arranged on one surface of substrate, and
the photocurable adhesive sheet according to item 12 above,
the light-emitting element of the display panel is sealed by the photocurable adhesive layer of the photocurable adhesive sheet,
the photocurable adhesive layer is cured.
[ additional notes 14] the self-luminous display device according to additional notes 13, wherein the display panel is an LED panel having a plurality of LED chips arranged on one surface of a substrate.
[ additional character 15] A method for manufacturing the self-luminous display device of the additional character 13 or 14, comprising the steps of:
laminating the photocurable adhesive layer of the photocurable adhesive sheet described in reference 12 on a display panel having a plurality of light-emitting elements arranged on one surface of a substrate, and sealing the light-emitting elements with the photocurable adhesive layer; and
and a step of irradiating the photocurable adhesive layer with ultraviolet rays to cure the layer.
[ appendix 16] the method according to appendix 15, wherein the ultraviolet light is ultraviolet light having a wavelength of less than 300 nm.
Industrial applicability
The photocurable adhesive sheet of the present invention is suitable for sealing a light emitting element of a self-luminous display device such as a mini/micro LED.
Description of the reference numerals
1A-1C photocurable adhesive sheet
10. Photocurable adhesive layer
10A one surface (adhesive surface)
10B another surface
S1 base material
S1A first side
S1B second face (Back)
S2-S4 peeling film
S5 optical component
50. Pressure-sensitive adhesive sheet with release film
100. Adhesive sheet-attached member
200A, 200B self-luminous display device (Mini/minitype LED display device)
20. Adhesive layer (after curing)
21. Substrate board
22. Metal wiring layer
23. Luminous element (LED chip)
24. Covering member

Claims (16)

1. An adhesive composition comprising a colorant and a polymer (A) having a benzophenone structure in a side chain,
the adhesive composition has a maximum value of transmittance at a wavelength of 200 to 400nm that is greater than a maximum value of transmittance at a wavelength of 400 to 700 nm.
2. An adhesive composition comprising a colorant and a partial polymer which is a mixture of monomer components constituting a polymer (A) having a benzophenone structure in a side chain or a mixture of monomer components constituting a polymer (A) having a benzophenone structure in a side chain,
the adhesive composition has a maximum value of transmittance at a wavelength of 200 to 400nm that is greater than a maximum value of transmittance at a wavelength of 400 to 700 nm.
3. The adhesive composition according to claim 1 or 2, wherein the colorant is a colorant in which the maximum value of transmittance at a wavelength of 200 to 400nm is larger than the maximum value of transmittance at a wavelength of 400 to 700 nm.
4. The adhesive composition according to any one of claims 1 to 3, further comprising an ethylenically unsaturated compound (B).
5. The adhesive composition according to any one of claims 1 to 4, further comprising a photopolymerization initiator (C) which absorbs ultraviolet light having a wavelength of 300nm to 500nm to generate radicals.
6. A photocurable adhesive layer formed from a cured product of the adhesive composition according to any one of claims 1 to 5,
the cured product is a cured product in which the benzophenone structure of the polymer (a) having a benzophenone structure in a side chain remains.
7. The photocurable adhesive layer according to claim 6, wherein the maximum value of transmittance at a wavelength of 200 to 400nm is larger than the maximum value of transmittance at a wavelength of 400 to 700 nm.
8. The photocurable adhesive layer according to claim 6 or 7, wherein the storage modulus (G' b 85) at 85 ℃ of the photocurable adhesive layer before curing is lower than 65kPa.
9. The photocurable adhesive layer according to any one of claims 6-8, wherein a storage modulus at 10 ℃ (G 'a 10) of the photocurable adhesive layer after curing and a storage modulus at 85 ℃ (G' b 85) of the photocurable adhesive layer before curing satisfy the following relational expression (1),
2.8<G'a10/G'b85 (1)。
10. the photocurable adhesive layer according to any one of claims 6-9, wherein the storage modulus (G' a 10) at 10 ℃ of the photocurable adhesive layer after curing is 90kPa or more.
11. The photocurable adhesive layer according to any one of claims 6-10, wherein the curing is based on a wavelength of less than 300nm and a cumulative light amount of 3000mJ/cm 2 Curing by ultraviolet irradiation.
12. A photocurable adhesive sheet having the photocurable adhesive layer according to any one of claims 6 to 11.
13. A self-luminous display device, comprising:
display panel having a plurality of light-emitting elements arranged on one surface of substrate, and
the photocurable adhesive sheet according to claim 12,
the light emitting element of the display panel is sealed by the photocurable adhesive layer of the photocurable adhesive sheet,
the photocurable adhesive layer is cured.
14. 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 surface of a substrate.
15. A method for manufacturing the self-luminous display device according to claim 13 or 14, comprising the steps of:
laminating the photocurable adhesive layer of the photocurable adhesive sheet according to claim 12 on a display panel having a plurality of light-emitting elements arranged on one surface of a substrate, and sealing the light-emitting elements with the photocurable adhesive layer; and
and a step of irradiating the photocurable adhesive layer with ultraviolet rays to cure the layer.
16. The manufacturing method according to claim 15, wherein the ultraviolet rays are ultraviolet rays having a wavelength of less than 300 nm.
CN202180053034.5A 2020-08-28 2021-08-24 Adhesive composition, photocurable adhesive layer, and photocurable adhesive sheet Pending CN115989143A (en)

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