CN113474702B - flexible laminate - Google Patents

flexible laminate Download PDF

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Publication number
CN113474702B
CN113474702B CN202080016727.2A CN202080016727A CN113474702B CN 113474702 B CN113474702 B CN 113474702B CN 202080016727 A CN202080016727 A CN 202080016727A CN 113474702 B CN113474702 B CN 113474702B
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adhesive
layer
adhesive layer
meth
adhesive composition
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CN113474702A (en
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李昇祐
金正熙
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Sumitomo Chemical Co Ltd
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Sumitomo Chemical Co Ltd
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • 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
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/022—Mechanical properties
    • 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
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/023—Optical properties
    • 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
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • 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
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • 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
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3083—Birefringent or phase retarding elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • 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
    • 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
    • G09F9/30—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements in which the desired character or characters are formed by combining individual elements
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K59/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
    • H10K59/50—OLEDs integrated with light modulating elements, e.g. with electrochromic elements, photochromic elements or liquid crystal elements

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Nonlinear Science (AREA)
  • Theoretical Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Organic Chemistry (AREA)
  • Mathematical Physics (AREA)
  • Mechanical Engineering (AREA)
  • Human Computer Interaction (AREA)
  • Adhesives Or Adhesive Processes (AREA)
  • Laminated Bodies (AREA)
  • Adhesive Tapes (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)
  • Polarising Elements (AREA)

Abstract

The purpose of the present invention is to provide a flexible laminate which suppresses the generation of air bubbles and has excellent adhesion even when the front panel side is repeatedly bent inward. The invention provides a flexible laminate comprising, in order, a front panel, a 1 st adhesive layer formed using a 1 st adhesive composition, a polarizer layer, a 2 nd adhesive layer formed using a 2 nd adhesive composition, and a back panel, wherein the following relational expression (1) is satisfied if the shear recovery rate of the 1 st adhesive layer at 25 ℃ is R1[% ], and the shear recovery rate of the 2 nd adhesive layer at 25 ℃ is R2[% ]: r1 is less than or equal to R2 (1).

Description

Flexible laminate
Technical Field
The present invention relates to flexible laminates.
Background
Japanese patent application laid-open No. 2018-28573 (patent document 1) describes a laminate for a flexible image display device having a plurality of adhesive layers.
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open No. 2018-28573
Disclosure of Invention
In a display device including a laminate having a front panel and a plurality of adhesive layers, when the front panel side is repeatedly bent outward, air bubbles may be generated in the adhesive layers in the laminate. In addition, the adhesive force of the adhesive layer is weak, and floating or peeling may occur between the adhesive layer and the adherend.
The purpose of the present invention is to provide a flexible laminate which suppresses the generation of air bubbles and has excellent adhesion even when the front panel side is repeatedly bent to the outside.
The present invention provides the following flexible laminate.
A flexible laminate comprising, in order, a front panel, a 1 st adhesive layer formed using a 1 st adhesive composition, a polarizer layer, a 2 nd adhesive layer formed using a 2 nd adhesive composition, and a back panel,
the following relational expression (1) is satisfied if the shear recovery rate at 25 ℃ of the 1 st adhesive layer is set to R1[% ], and the shear recovery rate at 25 ℃ of the 2 nd adhesive layer is set to R2[% ]:
R1≤R2 (1)。
the flexible laminate according to [ 1 ], wherein if the shear recovery rate at 25℃of the 1 st reference adhesive layer having a thickness of 200 μm formed using the 1 st adhesive composition is defined as R 0 1[％]The shear recovery rate at 25℃of a 2 nd reference adhesive layer having a thickness of 200 μm formed using the 2 nd adhesive composition was defined as R 0 2[％]The following relationships (2) and (3) are satisfied:
5≤R 0 1≤50 (2)
5≤R 0 2≤50 (3)。
the flexible laminate according to [ 1 ] or [ 2 ], wherein the 1 st adhesive composition and the 2 nd adhesive composition each contain a (meth) acrylic polymer,
The weight average molecular weight (Mw) of the (meth) acrylic polymer is 20 to 150 tens of thousands.
The flexible laminate according to any one of [ 1 ] to [ 3 ], wherein 1 or more retardation layers are provided between the polarizer layer and the back plate.
The flexible laminate according to any one of [ 1 ] to [ 4 ], wherein the back plate is a touch sensor panel.
A display device comprising the flexible laminate according to any one of [ 1 ] to [ 5 ].
According to the present invention, a flexible laminate excellent in adhesion and capable of suppressing the generation of bubbles even when the front panel side is repeatedly bent to the outside can be provided.
Drawings
Fig. 1 is a schematic cross-sectional view showing an example of a laminate of the present invention.
Fig. 2 is a schematic cross-sectional view showing an example of the laminate of the present invention.
Fig. 3 is a schematic diagram for explaining a method of bending test.
Fig. 4 is a cross-sectional view schematically showing a method for producing a laminate of the present invention.
Detailed Description
Hereinafter, a flexible laminate (hereinafter, also simply referred to as "laminate") according to an embodiment of the present invention will be described with reference to the drawings.
< laminate >
Fig. 1 is a schematic cross-sectional view of a laminate according to an embodiment of the present invention. The laminate 100 includes a front panel 101, a 1 st adhesive layer 102, a polarizer layer 103, a 2 nd adhesive layer 104, and a back panel 105 in this order. The 1 st adhesive layer 102 is formed of the 1 st adhesive composition, and the 2 nd adhesive layer 104 is formed of the 2 nd adhesive composition. Hereinafter, the 1 st adhesive layer 102 and the 2 nd adhesive layer 104 may be collectively referred to as an adhesive layer.
The thickness of the laminate 100 is not particularly limited, and is, for example, 50 μm to 4000 μm, preferably 100 μm to 2000 μm, and more preferably 150 μm to 1000 μm, because it varies depending on the function required for the laminate, the use of the laminate, and the like.
The planar shape of the laminate 100 may be, for example, a square shape, preferably a square shape having long sides and short sides, and more preferably a rectangle. When the laminate 100 has a rectangular shape in the planar direction, the length of the long side may be, for example, 10mm to 1400mm, and preferably 50mm to 600mm. The length of the short side is, for example, 5mm to 800mm, preferably 30mm to 500mm, more preferably 50mm to 300mm. The layers constituting the laminate may be formed by chamfering the corners, or by notching or punching the ends.
The laminate 100 can be used for a display device or the like, for example. The display device is not particularly limited, and examples thereof include an organic electroluminescence (organic EL) display device, an inorganic electroluminescence (inorganic EL) display device, a liquid crystal display device, and an electroluminescent display device. The display device may have a touch panel function.
[ shear recovery Rate of adhesive layer ]
Regarding the laminate 100, if the shear recovery rate at 25 ℃ of the 1 st adhesive layer 102 is set to R1[% ], and the shear recovery rate at 25 ℃ of the 2 nd adhesive layer 104 is set to R2[% ], the following relational expression (1) is satisfied:
R1≤R2 (1)，
more preferably, the following relational expression (1') is satisfied:
R1＜R2 (1’)。
as to whether the relation (1) or (1') is satisfied, there are:
i) Method for breaking based on each value of R1 and R2, and
ii) a method of determining based on other combinations having the same magnitude relationship as the combination of R1 and R2.
For another combination of ii) above, for example, in the case where the 1 st adhesive layer 102 and the 2 nd adhesive layer 104 have the same thickness, it can be determined by comparing the 1 st reference adhesive layer formed of the 1 st adhesive composition with the 2 nd reference adhesive layer formed of the 2 nd adhesive composition. The shear recovery rate R at 25 ℃ of the 1 st reference adhesive layer is as high as the 1 st reference adhesive layer and the 2 nd reference adhesive layer are the same in thickness 0 1[％]And a shear recovery rate R of the 2 nd reference adhesive layer at 25 DEG C 0 2[％]Satisfies the following relation (1 a): r is R 0 1≤R 0 2 (1 a) can be regarded as satisfying the relation (1); satisfies the following relational expression (1' a): r is R 0 1＜R 0 2 (1 'a) can be regarded as satisfying the relation (1'). 1 st reference adhesive layer having a thickness of 200 μm and 2 nd reference adhesive layer having a shear recovery rate R at 25 DEG C 0 1、R 0 2 the measurement was performed according to the measurement method described in the example column below.
The laminate 100 can be bent with the front panel 101 side being the outer side. In a display device including a laminate, if the front panel side is repeatedly bent to the outside, air bubbles may be generated in the adhesive layer. The generation of the bubbles is particularly remarkable in the adhesive layer on the side away from the front panel, that is, the 2 nd adhesive layer 104 in the laminate 100. As a result of the study, the inventors of the present invention found that when the shear recovery rates of the 1 st adhesive layer 102 and the 2 nd adhesive layer 104 satisfy the relation (1), the occurrence of air bubbles in the adhesive layers in the laminate 100 can be suppressed even when the front panel 101 side is repeatedly bent to the outside. More specifically, it was found that even if the laminate 100 is repeatedly bent 2 ten thousand times so that the bending radius of the inner surface of the laminate 100 is 3mm, the generation of bubbles in the adhesive layer in the laminate 100 can be suppressed (hereinafter, also referred to as having excellent "normal temperature bendability"). The room temperature bendability can be evaluated by the evaluation method described in the example column. The laminate 100 may be bent with the front panel side inside. The display device to which the laminate 100 is applied can be used as a flexible display that can be bent, rolled, or the like. In the present specification, the bending includes a bending form in which a curved surface is formed at a bending portion, and a bending radius of an inner surface of the bending is not particularly limited. In addition, the bending also includes bending in which the bending angle of the inner surface is greater than 0 degrees and less than 180 degrees, and folding in which the bending radius of the inner surface is approximately zero or the bending angle of the inner surface is 0 degrees.
The shear recovery rate at 25℃of the 1 st reference adhesive layer having a thickness of 200 μm was defined as R 0 1[％]And the shear recovery rate at 25 ℃ of the 2 nd reference adhesive layer with a thickness of 200 μm is set as R 0 2[％]When it is fullThe following relationships (2) and (3) are followed:
5≤R 0 1≤50 (2)
5≤R 0 2≤50 (3)，
more preferably, the following relational expressions (2 a) and (3 a) are satisfied:
5≤R 0 1≤45 (2a)
5≤R 0 2≤45 (3a)。
examples of the method for preparing the 1 st adhesive composition and the 2 nd adhesive composition so that the shear recovery rate of the 1 st adhesive layer 102 and the 2 nd adhesive layer 104 satisfies the relation (1) include a method for forming an adhesive layer from an adhesive composition a described later, a method for changing the type of a monomer constituting the (meth) acrylic polymer a described later, a method for adjusting the molecular weight of the (meth) acrylic polymer a, or a method for containing a compound having a urethane group.
[ adhesive composition ]
In one embodiment, the 1 st adhesive layer 102 and the 2 nd adhesive layer 104 are formed of an adhesive composition (hereinafter, also referred to as an adhesive composition a) containing a (meth) acrylic polymer. The adhesive composition a may be an active energy ray-curable type or a thermosetting type. In the present specification, "a" (meth) acrylic polymer "means at least 1 selected from the group consisting of an acrylic polymer and a methacrylic polymer. The same applies to other expressions labeled "(methyl)". When the 1 st adhesive composition and the 2 nd adhesive composition both contain a (meth) acrylic polymer, the (meth) acrylic polymers may be the same or different. Hereinafter, the (meth) acrylic polymer contained in the adhesive composition a is also referred to as a (meth) acrylic polymer a.
The weight average molecular weight (Mw) of the (meth) acrylic polymer a is preferably 20 to 150 ten thousand, more preferably 30 to 120 ten thousand, from the viewpoint that the obtained adhesive layer easily satisfies the relation (2) or the relation (3).
In the (meth) acrylic polymer a, the structural unit derived from the monomer having a reactive functional group is preferably less than 5% by mass based on the total mass of the polymer. Examples of the reactive functional group include a hydroxyl group, a carboxyl group, an amino group, an amide group, and an epoxy group. This increases the flexibility of the adhesive layer, and tends to easily suppress the generation of bubbles in the adhesive layer. In the (meth) acrylic polymer a, the structural unit derived from the monomer having a reactive functional group is more preferably 0.01 mass% or less based on the total mass of the polymer, even more preferably no structural unit derived from the monomer having a reactive functional group, even more preferably no hydroxyl group, carboxyl group, amino group, amide group and epoxy group, from the viewpoint of suppressing bubbles at the time of bending.
(1) Active energy ray-curable adhesive composition
When the adhesive composition a is an active energy ray-curable adhesive composition, the (meth) acrylic polymer a contained in the adhesive composition a may contain a structural unit derived from a (meth) acrylic monomer having a linear or branched alkyl group having 1 to 24 carbon atoms. Examples of the (meth) acrylic monomer having a linear or branched alkyl group having 1 to 24 carbon atoms include alkyl (meth) acrylate, and examples thereof include butyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, isooctyl (meth) acrylate, isodecyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isobornyl (meth) acrylate. The (meth) acrylic polymer a may be a polymer or copolymer containing 1 or 2 or more kinds of the above alkyl (meth) acrylate as monomers. The content of the (meth) acrylic polymer a in the adhesive composition a may be, for example, 50 to 100% by mass, preferably 80 to 99.5% by mass, and more preferably 90 to 99% by mass, relative to 100 parts by mass of the solid content of the adhesive composition a.
The weight average molecular weight (Mw) of the (meth) acrylic polymer a may be, for example, 20 to 80 tens of thousands, and is preferably 30 to 70 tens of thousands from the viewpoint of suppressing bubbles at the time of bending. The weight average molecular weight (Mw) can be measured according to the measurement method described in the example column below.
The adhesive composition a may contain 1 or 2 or more (meth) acrylic polymers a. The adhesive composition a may contain only the (meth) acrylic polymer a as a constituent component thereof, or may further contain a crosslinking agent. Examples of the crosslinking agent include metal ions having a valence of 2 or more which form a metal carboxylate with a carboxyl group; polyamine compounds forming an amide bond with carboxyl groups; polyepoxides or polyols which form ester bonds with carboxyl groups; and a polyisocyanate compound forming an amide bond with a carboxyl group. Among them, polyisocyanate compounds are preferable. When the adhesive composition a contains a crosslinking agent, the content of the crosslinking agent may be, for example, 5 parts by mass or less, preferably 1 part by mass or less, more preferably 0.5 part by mass or less, still more preferably 0.1 part by mass or less, relative to 100 parts by mass of the (meth) acrylic polymer a, and the adhesive composition a most preferably contains no crosslinking agent.
The active energy ray-curable adhesive composition refers to an adhesive composition having the following properties: the adhesive agent is cured by irradiation with active energy rays such as ultraviolet rays and electron beams, and has adhesion properties even before irradiation with active energy rays, and can adhere to an adherend such as a film, and the adhesive force can be adjusted by curing by irradiation with active energy rays.
The active energy ray-curable adhesive composition is preferably an ultraviolet ray-curable adhesive composition.
When the adhesive composition a is an active energy ray-curable adhesive composition, the adhesive composition a may further contain an active energy ray-polymerizable compound, a photopolymerization initiator, a photosensitizer, and the like.
Examples of the active energy ray-polymerizable compound include (meth) acrylate monomers having at least one (meth) acryloyloxy group in a molecule; (meth) acrylic compounds such as (meth) acryloyloxy group-containing compounds, such as (meth) acrylate oligomers having at least 2 (meth) acryloyloxy groups in the molecule, obtained by reacting 2 or more functional group-containing compounds. The adhesive composition a may contain 0.1 to 10 parts by mass of the active energy ray-polymerizable compound per 100 parts by mass of the solid content of the adhesive composition a.
Examples of the photopolymerization initiator include diphenyl (2, 4, 6-trimethylbenzoyl) phosphine oxide, benzil dimethyl ketal, and 1-hydroxycyclohexyl phenyl ketone. When the adhesive composition a contains a photopolymerization initiator, it may contain 1 or 2 or more. When the adhesive composition a contains a photopolymerization initiator, the total content thereof may be, for example, 0.01 to 1.0 parts by mass relative to 100 parts by mass of the solid content of the adhesive composition a.
The adhesive composition a preferably contains a compound having a urethane group. Preferably, at least one of the 1 st adhesive composition and the 2 nd adhesive composition is an adhesive composition a containing a compound having a urethane group. The 1 st reference adhesive layer and the 2 nd reference adhesive layer satisfying the above-described relational expressions (2) and (3) can be easily formed by the adhesive composition a containing the compound having the urethane group. The pressure-sensitive adhesive composition a may contain, for example, 0.1 to 10 parts by mass, preferably 1 to 5 parts by mass of a compound having a urethane group in 100 parts by mass of the solid content of the pressure-sensitive adhesive composition a. The content of the compound having a urethane group can be adjusted so as to satisfy the above-described relational expressions (2) and (3), and the shear recovery rate at 25 ℃ of the reference pressure-sensitive adhesive layer can be improved by increasing the content of the compound having a urethane group.
The urethane group-containing compound is not particularly limited as long as it has a urethane bond, and urethane acrylates and the like can be exemplified. Specific examples of the compound having a urethane group include aliphatic monofunctional urethane acrylates and the like.
The adhesive composition a may contain fine particles for imparting light scattering properties, beads (resin beads, glass beads, etc.), glass fibers, resins other than the base polymer, an adhesion imparting agent, a filler (metal powder, other inorganic powder, etc.), an antioxidant, an ultraviolet absorber, a dye, a pigment, a colorant, a defoaming agent, an anticorrosive agent, and other additives. From the viewpoint of preventing the problem of deterioration of durability due to residual solvents, it is preferable that the adhesive composition a contains no organic solvent.
When the adhesive layer is formed of the adhesive composition a, the adhesive layer may be formed by coating the adhesive composition a on a substrate. When the active energy ray-curable adhesive composition is used, a cured product having a desired degree of cure can be produced by irradiating the formed adhesive layer with active energy rays.
(2) Heat-curable adhesive composition
When the adhesive composition a is a thermosetting adhesive composition, the (meth) acrylic polymer a preferably contains an alkyl (meth) acrylate having an alkyl group with 2 to 20 carbon atoms and a monomer having a reactive functional group in the molecule (a monomer having a reactive functional group) as monomer units constituting the polymer.
The (meth) acrylic polymer a can exhibit a desirable adhesion property by containing an alkyl (meth) acrylate having 2 to 20 carbon atoms as an alkyl group as a monomer unit constituting the polymer. The alkyl (meth) acrylate having 2 to 20 carbon atoms as the alkyl group is preferably an alkyl (meth) acrylate having a glass transition temperature (Tg) of-40℃or lower (hereinafter, sometimes referred to as "low Tg alkyl acrylate") as a homopolymer. By containing the low Tg alkyl acrylate as a constituent monomer unit, the flexibility of the pressure-sensitive adhesive layer is improved, and the occurrence of bubbles during bending tends to be easily suppressed.
As the low Tg alkyl acrylate, for example, n-butyl acrylate (Tg of-55 ℃), n-octyl acrylate (Tg of-65 ℃), isooctyl acrylate (Tg of-58 ℃), 2-ethylhexyl acrylate (Tg of-70 ℃), isononyl acrylate (Tg of-58 ℃), isodecyl acrylate (Tg of-60 ℃), isodecyl methacrylate (Tg of-41 ℃), n-lauryl methacrylate (Tg of-65 ℃), tridecyl acrylate (Tg of-55 ℃), tridecyl methacrylate (-40 ℃), etc. are preferable. Among them, from the viewpoint of easy satisfaction of the relation (2) or the relation (3), the low Tg alkyl acrylate is more preferably an alkyl acrylate having a homopolymer Tg of-45 ℃ or less, particularly preferably an alkyl acrylate having a Tg of-50 ℃ or less. In particular, n-butyl acrylate and 2-ethylhexyl acrylate are particularly preferred. These may be used alone or in combination of 2 or more.
The (meth) acrylic polymer a preferably contains 85 mass% or more, more preferably 90 mass% or more, and still more preferably 95 mass% or more of the low Tg alkyl acrylate as the monomer unit constituting the polymer.
If the content is within such a range, the resulting adhesive layer easily satisfies the relational expression (2) or the relational expression (3).
The (meth) acrylic polymer a preferably contains 99.9 mass% or less, more preferably 99.5 mass% or less, and still more preferably 99 mass% or less of the low Tg alkyl acrylate, as the upper limit of the monomer units constituting the polymer. By containing 99.9 mass% or less of the low Tg alkyl acrylate, an appropriate amount of other monomer components (particularly, reactive functional group-containing monomers) can be introduced into the (meth) acrylic polymer a.
In order to easily set the glass transition temperature (Tg) of the main polymer of the adhesive of the present embodiment within the above-described range, the content of the monomer (hereinafter, sometimes referred to as "hard monomer") having a glass transition temperature (Tg) exceeding 0 ℃ as a homopolymer is preferably reduced as much as possible. Specifically, in the (meth) acrylic polymer a, the content of the hard monomer is preferably 15 mass% or less, more preferably 10 mass% or less, and still more preferably 5 mass% or less, in terms of the upper limit value, of the monomer units constituting the polymer. The hard monomer also includes a reactive functional group-containing monomer described later.
Examples of the hard monomer include methyl acrylate (Tg of 10 ℃), methyl methacrylate (Tg of 105 ℃), ethyl methacrylate (Tg of 65 ℃), n-butyl methacrylate (Tg of 20 ℃), isobutyl methacrylate (Tg of 48 ℃), t-butyl methacrylate (Tg of 107 ℃), n-stearyl acrylate (Tg of 30 ℃), n-stearyl methacrylate (Tg of 38 ℃), cyclohexyl acrylate (Tg of 15 ℃), cyclohexyl methacrylate (Tg of 66 ℃), phenoxyethyl acrylate (Tg of 5 ℃), phenoxyethyl methacrylate (Tg of 54 ℃), benzyl methacrylate (Tg of 54 ℃), isobornyl acrylate (Tg of 94 ℃), isobornyl methacrylate (Tg of 180 ℃), acryloylmorpholine (Tg of 145 ℃), adamantyl acrylate (Tg of 115 ℃), adamantyl methacrylate (Tg of 141), acrylic acid (Tg of 103 ℃), dimethylacrylamide (Tg of 89 ℃), acrylamide (Tg of 15 ℃), vinyl acetate (Tg of 165), and the like, and vinyl acetate (of 32 ℃).
The (meth) acrylic polymer a has a crosslinked structure (three-dimensional network structure) by reacting a reactive functional group derived from a reactive functional group-containing monomer as a monomer unit constituting the polymer with a thermal crosslinking agent described later to form a crosslinked structure (three-dimensional network structure), thereby obtaining a pressure-sensitive adhesive having a desired cohesive force.
The reactive functional group-containing monomer contained in the (meth) acrylic polymer a as the monomer unit constituting the polymer may preferably be a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl group-containing monomer), a monomer having an amino group in the molecule (amino group-containing monomer), or the like. Among these, hydroxyl group-containing monomers are particularly preferred from the viewpoint of a large number of monomers having a glass transition temperature (Tg) of 0℃or lower.
Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. Among them, at least one of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate and 4-hydroxybutyl acrylate is preferable from the viewpoints of glass transition temperature (Tg), reactivity of hydroxyl groups in the obtained (meth) acrylic polymer a with a thermal crosslinking agent, and copolymerizability with other monomers. These may be used alone or in combination of 2 or more.
Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These may be used alone or in combination of 2 or more.
Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, n-butylaminoethyl (meth) acrylate, and the like. These may be used alone or in combination of 2 or more.
The (meth) acrylic polymer a preferably contains 0.1 mass% or more, particularly preferably 0.5 mass% or more, and further preferably 1 mass% or more of a reactive functional group-containing monomer, as a monomer unit constituting the polymer, in terms of the lower limit value. The content of the organic compound is preferably 10% by mass or less, particularly preferably 8% by mass or less, and further preferably less than 5% by mass, based on the upper limit. If the (meth) acrylic polymer a contains a reactive functional group-containing monomer, particularly a hydroxyl group-containing monomer, as a monomer unit in the above-described amount, the resulting adhesive layer easily satisfies the relationship (2) or the relationship (3).
The (meth) acrylic polymer a may contain no carboxyl group-containing monomer, particularly acrylic acid which is also a hard monomer, as a monomer unit constituting the polymer. Since the carboxyl group is an acid component, by not containing a carboxyl group-containing monomer, even when a member causing a problem due to acid, for example, a transparent conductive film such as tin-doped indium oxide (ITO), a metal film, a metal mesh, or the like is present in the object to be adhered of the adhesive, the problem (corrosion, change in resistance value, or the like) caused by acid can be suppressed.
The (meth) acrylic polymer a may contain other monomers as monomer units constituting the polymer, as desired. As the other monomer, a monomer having a reactive functional group is also preferably not contained so as not to interfere with the action of the reactive functional group-containing monomer. Examples of the other monomer include an alkoxyalkyl (meth) acrylate such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, and a monomer having a glass transition temperature (Tg) of more than-40 ℃ and not more than 0 ℃ as a homopolymer (hereinafter, sometimes referred to as a "medium Tg alkyl acrylate"). Examples of the alkyl acrylate having a medium Tg include ethyl acrylate (Tg of-20 ℃), isobutyl acrylate (Tg of-26 ℃), 2-ethylhexyl methacrylate (Tg of-10 ℃), n-lauryl acrylate (Tg of-23 ℃), and isostearyl acrylate (Tg of-18 ℃). These may be used alone or in combination of 2 or more.
The polymerization system of the (meth) acrylic polymer a may be a random copolymer or a block copolymer.
The lower limit of the weight average molecular weight of the (meth) acrylic polymer a is preferably 20 ten thousand or more, particularly preferably 30 ten thousand or more, and further preferably 40 ten thousand or more. If the lower limit of the weight average molecular weight of the (meth) acrylic polymer a is not less than the above, the adhesive bleeding and other defects can be suppressed. The weight average molecular weight in the present specification is a value in terms of standard polystyrene measured by Gel Permeation Chromatography (GPC).
The upper limit of the weight average molecular weight of the (meth) acrylic polymer a is preferably 150 ten thousand or less, particularly preferably 135 ten thousand or less, and further preferably 120 ten thousand or less. If the upper limit of the weight average molecular weight of the (meth) acrylate polymer (a) is not more than the above, the obtained adhesive layer easily satisfies the relation (2) or the relation (3).
In the pressure-sensitive adhesive composition a, 1 kind of the (meth) acrylic polymer a may be used alone, or 2 or more kinds may be used in combination.
If the adhesive composition A containing the thermal crosslinking agent is heated, the thermal crosslinking agent crosslinks the (meth) acrylic polymer A to form a three-dimensional network structure. Thus, the cohesive force of the obtained adhesive increases, and the obtained adhesive layer easily satisfies the relational expression (2) or the relational expression (3).
The thermal crosslinking agent may be one that reacts with the reactive group of the (meth) acrylic polymer a, and examples thereof include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, and aldehydes-based crosslinking agentsA cross-linking agent,An oxazoline-based crosslinking agent, a metal alkoxide-based crosslinking agent, a metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, an ammonium salt-based crosslinking agent, and the like. Among the above, when the reactive group of the (meth) acrylic polymer a is a hydroxyl group, an isocyanate-based crosslinking agent having excellent reactivity with the hydroxyl group is preferably used. The thermal crosslinking agent may be used alone or in combination of 1 or more than 2.
The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate, and hydrogenated diphenylmethane diisocyanate, and the like, and biuret and isocyanurate thereof, and adducts as reactants with low-molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among them, from the viewpoint of reactivity with hydroxyl groups, trimethylolpropane-modified aromatic polyisocyanates are preferred, and trimethylolpropane-modified toluene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are particularly preferred.
Examples of the epoxy-based crosslinking agent include 1, 3-bis (N, N-diglycidyl aminomethyl) cyclohexane, N' -tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine, and the like.
The content of the thermal crosslinking agent in the adhesive composition a is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, and still more preferably 0.1 mass% or more, relative to 100 mass% of the (meth) acrylic polymer a. The content is preferably 1% by mass or less, more preferably 0.8% by mass or less, and still more preferably 0.5% by mass or less. When the content of the thermal crosslinking agent is in the above range, the obtained adhesive layer easily satisfies the relational expression (2) or the relational expression (3).
The adhesive composition a preferably contains the above-mentioned silane coupling agent. Thus, the adhesion between the obtained adhesive layer and each member in the flexible laminate as an adherend is improved, and the durability against bending is further improved.
The silane coupling agent is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule, and has good compatibility with the (meth) acrylic polymer a and light transmittance.
Examples of the silane coupling agent include silicon compounds having a polymerizable unsaturated group such as vinyltrimethoxysilane, vinyltriethoxysilane, methacryloxypropyl trimethoxysilane, 3-glycidoxypropyl trimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, silicon compounds having an epoxy structure such as 3-mercaptopropyl trimethoxysilane, 3-mercaptopropyl triethoxysilane, 3-mercaptopropyl dimethoxymethylsilane, and silicon compounds having a mercapto group such as 3-aminopropyl trimethoxysilane, silicon compounds having an amino group such as N- (2-aminoethyl) -3-aminopropyl trimethoxysilane, N- (2-aminoethyl) -3-aminopropyl methyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-isocyanatopropyl triethoxysilane, and condensates of at least one of them with silicon compounds having an alkyl group such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, and ethyltrimethoxysilane. These may be used alone or in combination of 1 or more than 2.
The content of the silane coupling agent in the adhesive composition a is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, and still more preferably 0.1 mass% or more, relative to 100 mass% of the (meth) acrylic polymer a. The content is preferably 1% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.3% by mass or less. The content of the silane coupling agent in the above range makes the adhesion between the obtained adhesive layer and each member in the flexible laminate as an adherend more preferable.
The adhesive composition a may contain various additives as described above, as desired. The polymerization solvent and the dilution solvent are not included in the additives constituting the adhesive composition a.
The (meth) acrylic polymer a can be produced by polymerizing a mixture of monomers constituting the polymer by a usual radical polymerization method. The polymerization of the (meth) acrylic polymer a is preferably carried out by a solution polymerization method using a polymerization initiator as desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more of them may be used in combination.
The polymerization initiator may be an azo compound, an organic peroxide, or the like, and two or more kinds may be used in combination. As the azo-based compound, for example, examples thereof include 2,2' -azobisisobutyronitrile, 2' -azobis (2-methylbutyronitrile), 1' -azobis (cyclohexane 1-carbonitrile), 2' -azobis (2, 4-dimethylvaleronitrile), 2' -azobis (2, 4-dimethyl-4-methoxyvaleronitrile), and dimethyl 2,2' -azobis (2-methylpropionate), 4' -azobis (4-cyanovaleric acid), 2' -azobis (2-hydroxymethylpropionitrile), 2' -azobis [2- (2-imidazolin-2-yl) propane ], and the like.
Examples of the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxyethyl) peroxydicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxyvalerate, (3, 5-trimethylhexanoyl) peroxide, dipropyl peroxide, and diacetyl peroxide.
In the polymerization step, a chain transfer agent such as 2-mercaptoethanol is blended to adjust the weight average molecular weight of the obtained polymer.
After the (meth) acrylic polymer a is obtained, a thermal crosslinking agent, a silane coupling agent, and, if desired, an additive and a diluting solvent are added to the solution of the (meth) acrylic polymer a and thoroughly mixed to obtain a solvent-diluted adhesive composition a (coating solution).
In the case where a solid substance is used or where precipitation occurs when the solid substance is mixed with other components in an undiluted state, the components may be dissolved or diluted in a diluting solvent alone and then mixed with other components.
Examples of the diluent solvent include aliphatic hydrocarbons such as hexane, heptane and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and dichloroethane, alcohols such as methanol, ethanol, propanol, butanol and 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, cellosolve solvents such as ethyl cellosolve, and the like.
The concentration and viscosity of the coating solution thus prepared are not particularly limited as long as they are within a coatable range, and may be appropriately selected according to the situation. For example, the adhesive composition a is diluted so that the concentration thereof is 10 to 60 mass%. In addition, the addition of a diluting solvent or the like is not a necessary condition in obtaining the coating solution, and the diluting solvent may not be added as long as the adhesive composition a has a coatable viscosity or the like. In this case, the adhesive composition a is a coating solution in which the polymerization solvent of the (meth) acrylic polymer a is directly used as a diluting solvent.
The adhesive agent which is preferable as the adhesive agent of the present embodiment is obtained by crosslinking the adhesive agent composition a. Crosslinking of the adhesive composition a may be performed by a heat treatment. The heat treatment may be used in combination with a drying treatment when a diluting solvent or the like is volatilized from a coating film of the adhesive composition a applied to a desired object.
The heating temperature of the heating treatment is preferably 50 to 150 ℃, more preferably 70 to 120 ℃. The heating time is preferably 10 seconds to 10 minutes, more preferably 50 seconds to 2 minutes.
After the heat treatment, a curing period of about 1 to 2 weeks at normal temperature (for example, 23 ℃ C., 50% RH) may be set as needed. When the aging period is required, the adhesive is formed after the aging period, and when the aging period is not required, the adhesive is formed after the heat treatment is completed.
By the above-mentioned heat treatment (and curing), the (meth) acrylic polymer a is sufficiently crosslinked by the crosslinking agent to form a crosslinked structure, thereby obtaining the adhesive. The above adhesive easily satisfies the relation (2) or the relation (3) with respect to the obtained adhesive layer.
The adhesive sheet of the present invention comprises the above-described adhesive layer formed of the adhesive composition a of the present invention. The adhesive layer may be formed by coating the adhesive composition a on a substrate. When a thermosetting adhesive composition is used as the adhesive composition a, a cured product having a desired degree of cure can be produced by subjecting the formed adhesive layer to a heat treatment (and curing). The conditions for heat treatment and aging were as described above.
The substrate may be a release film subjected to a release treatment. The pressure-sensitive adhesive sheet can be produced by forming a layer of a pressure-sensitive adhesive on a release film in advance in a sheet form, and further laminating another release film on the pressure-sensitive adhesive layer.
As a method of applying the coating liquid of the adhesive composition a, for example, bar coating, knife coating, roll coating, blade coating, die coating, gravure coating, or the like can be used.
The adhesive composition a can be produced by mixing the components together by a known method, for example, using a mixer or the like.
[ front panel ]
The front panel 101 is not limited to a material and a thickness as long as it is a plate-like body that transmits light, and may be composed of only 1 layer or 2 or more layers. Examples thereof include a resin plate-like body (e.g., a resin plate, a resin sheet, a resin film, etc.), a glass plate-like body (e.g., a glass plate, a glass film, etc.), and a touch sensor panel described later. The front panel may constitute the outermost surface of the display device.
The thickness of the front panel 101 may be, for example, 10 μm to 500 μm, preferably 30 μm to 200 μm, and more preferably 50 μm to 100 μm. In the present invention, the thickness of each layer can be measured by the thickness measurement method described in examples described below.
When the front panel 101 is a resin plate-like body, the resin plate-like body is not limited as long as light can be transmitted therethrough. Examples of the resin constituting the resin plate-like body such as a resin film include films made of a polymer such as triacetylcellulose, cellulose acetate butyrate, ethylene-vinyl acetate copolymer, propionylcellulose, butyrylcellulose, levulinyl cellulose, polyester, polystyrene, polyamide, polyetherimide, poly (meth) acrylic acid, polyimide, polyethersulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyetherketone, polyetheretherketone, polyethersulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, and polyamideimide. These polymers may be used alone or in a mixture of 2 or more. From the viewpoint of improving strength and transparency, a resin film formed of a polymer such as polyimide, polyamide, or polyamideimide is preferable.
From the viewpoint of improving the hardness, the front panel 101 is preferably a film having a hard coat layer provided on at least one surface of a base film. As the base film, a film formed of the above resin can be used. The hard coat layer may be formed on one surface or both surfaces of the base film. By providing the hard coat layer, a resin film having improved hardness and scratch resistance can be produced. The hard coat layer is, for example, a cured layer of an ultraviolet curable resin. Examples of the ultraviolet curable resin include acrylic resins, silicone resins, polyester resins, urethane resins, amide resins, and epoxy resins. The hard coat layer may contain additives for improving hardness. The additive is not limited, and examples thereof include inorganic fine particles, organic fine particles, or a mixture thereof.
When the front panel 101 is a glass plate, the glass plate is preferably reinforced glass for display. The thickness of the glass plate may be, for example, 10 μm to 1000 μm. By using a glass plate, the front panel 101 having excellent mechanical strength and surface hardness can be constituted.
When the laminate 100 is used in a display device, the front panel 101 may be a front panel having not only a function of protecting the front surface (screen) of the display device (a function as a window film) but also a function as a touch sensor, a blue light cut-off function, a viewing angle adjustment function, and the like.
[ 1 st adhesive layer ]
The 1 st pressure-sensitive adhesive layer 102 is a layer interposed between the front panel 101 and the polarizer layer 103 and bonded to each other, and may be a layer made of a pressure-sensitive adhesive or an adhesive, or a layer obtained by subjecting the layer to a certain treatment. The 1 st adhesive layer may be an adhesive layer disposed at a position closest to the front panel among the adhesive layers constituting the laminate. Adhesives are also known as pressure sensitive adhesives. In the present specification, "adhesive" means an adhesive other than an adhesive (pressure-sensitive adhesive), and is clearly distinguished from an adhesive. The 1 st adhesive layer 102 may be composed of 1 layer, or may be composed of 2 or more layers, and preferably 1 layer.
The 1 st adhesive layer 20 may be formed directly from an adhesive composition, or may be formed using an adhesive sheet having an adhesive layer formed using an adhesive composition. The adhesive composition may be formed from adhesive composition a as described above.
The thickness of the 1 st pressure-sensitive adhesive layer 102 is, for example, preferably 3 μm to 100. Mu.m, more preferably 5 μm to 50. Mu.m, and may be 20 μm or more.
[ polarizer layer ]
Examples of the polarizer layer 103 include a stretched film or a stretched layer having a dichroic dye adsorbed thereto, and a layer obtained by applying a composition containing a dichroic dye and a polymerizable compound and curing the composition. As the dichroic dye, specifically, iodine or a dichroic organic dye can be used. The dichroic organic dye includes a dichroic direct dye composed of a disazo compound such as c.i. direct RED (c.i. direct RED) 39, and a dichroic direct dye composed of a compound such as trisazo or tetraazo.
Examples of the polarizer layer formed by applying and curing a composition containing a dichroic dye and a polymerizable compound include a polarizer layer containing a cured product of a polymerizable liquid crystal compound, such as a layer formed by applying and curing a composition containing a dichroic dye having liquid crystallinity or a composition containing a dichroic dye and a polymerizable liquid crystal.
A polarizer layer obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound is preferable because the bending direction is not limited as compared with a stretched film or a stretched layer to which the dichroic dye is adsorbed.
[ polarizer layer as stretched film or stretched layer ]
The polarizer layer as a stretched film having a dichroic dye adsorbed thereto can be generally produced by the following steps: a step of uniaxially stretching a polyvinyl alcohol resin film, a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol resin film with the dichroic dye, a step of treating the polyvinyl alcohol resin film adsorbed with the dichroic dye with an aqueous boric acid solution, and a step of washing with water after the treatment with the aqueous boric acid solution.
The thickness of the polarizer layer 103 is, for example, 2 μm to 40 μm. The thickness of the polarizer layer 103 may be 5 μm or more, or 20 μm or less, or more preferably 15 μm or less, and still more preferably 10 μm or less.
The polyvinyl alcohol resin can be obtained by saponifying a polyvinyl acetate resin. As the polyvinyl acetate-based resin, a copolymer of vinyl acetate and other monomers copolymerizable therewith may be used in addition to polyvinyl acetate which is a homopolymer of vinyl acetate. Examples of the other monomer copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth) acrylamides having an ammonium group.
The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with an aldehyde may be used. The polymerization degree of the polyvinyl alcohol resin is usually 1000 to 10000, preferably 1500 to 5000.
The polarizer layer as the stretched layer having the dichroic dye adsorbed thereto can be generally manufactured by the following process: a step of applying a coating liquid containing the polyvinyl alcohol resin onto a base film; a step of uniaxially stretching the obtained laminated film; a step of forming a polarizer layer by dyeing a polyvinyl alcohol resin layer of a uniaxially stretched laminate film with a dichroic dye to adsorb the dichroic dye, and a step of treating the film adsorbed with the dichroic dye with an aqueous boric acid solution; and a step of washing with water after the treatment with the aqueous boric acid solution.
The substrate film may be peeled off from the polarizer layer as needed. The material and thickness of the base film may be the same as those of the thermoplastic resin film described later.
The polarizer layer as a stretched film or a stretched layer may be assembled in a laminate in such a manner that a thermoplastic resin film is bonded to one or both surfaces thereof. The thermoplastic resin film may function as a protective film or a retardation film for the polarizer layer 103. The thermoplastic resin film may be a polyolefin resin such as a chain polyolefin resin (polypropylene resin or the like) or a cyclic polyolefin resin (norbornene resin or the like); cellulose resins such as triacetyl cellulose; polyester resins such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate; a polycarbonate resin; (meth) acrylic resins; or a mixture thereof, or the like.
From the viewpoint of thickness reduction, the thickness of the thermoplastic resin film is usually 300 μm or less, preferably 200 μm or less, more preferably 100 μm or less, still more preferably 80 μm or less, still more preferably 60 μm or less, and further usually 5 μm or more, preferably 20 μm or more.
The thermoplastic resin film may or may not have a retardation.
The thermoplastic resin film may be bonded to the polarizer layer 103 using an adhesive layer, for example.
[ polarizer layer obtained by applying and curing a composition containing a dichroic dye and a polymerizable compound ]
Examples of the polarizer layer formed by applying and curing a composition containing a dichroic dye and a polymerizable compound include a polarizer layer containing a cured product of a polymerizable liquid crystal compound, such as a layer obtained by applying and curing a composition containing a dichroic dye having liquid crystallinity or a composition containing a dichroic dye and a polymerizable liquid crystal to a base film.
The substrate film may be peeled off from the polarizer layer as needed. The material and thickness of the base film may be the same as those of the thermoplastic resin film described above. The polarizer layer may be provided with an alignment film. The orientation film may be peeled off.
The polarizer layer obtained by applying and curing the composition containing the dichroic dye and the polymerizable compound may be incorporated into the optical laminate in a state in which a thermoplastic resin film is bonded to one or both surfaces thereof. As the thermoplastic resin film, the same film as that which can be used in the polarizer layer as the stretched film or the stretched layer can be used. The thermoplastic resin film may be bonded to the polarizer layer using an adhesive layer, for example.
The polarizer layer formed by applying and curing a composition containing a dichroic dye and a polymerizable compound may have an Overcoat (OC) layer formed on one or both sides thereof as a protective layer. Examples thereof include photocurable resins and water-soluble polymers. Examples of the photocurable resin include (meth) acrylic resins, urethane resins, (meth) acrylic urethane resins, epoxy resins, and silicone resins. Examples of the water-soluble polymer include poly (meth) acrylamide polymers; polyvinyl alcohol, and vinyl alcohol polymers such as ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, and (meth) acrylic acid or acid anhydride-vinyl alcohol copolymer; carboxyvinyl polymers; polyvinylpyrrolidone; starches; sodium alginate; polyethylene oxide polymers, and the like. The thickness of the OC layer is preferably 20 μm or less, more preferably 15 μm or less, still more preferably 10 μm or less, and may be 5 μm or less, and further 0.05 μm or more, and may be 0.5 μm or more.
The thickness of the polarizer layer obtained by applying and curing the composition containing the dichroic dye and the polymerizable compound is usually 10 μm or less, preferably 0.5 μm to 8 μm, and more preferably 1 μm to 5 μm.
[ adhesive layer 2 ]
The 2 nd adhesive layer 104 is an adhesive layer disposed between the polarizer layer 103 and the back plate 105. The 2 nd adhesive layer may be an adhesive layer disposed at a position closest to the back surface plate among the adhesive layers constituting the laminate. The 2 nd adhesive layer 104 may be 1 layer, or may be composed of 2 or more layers, and is preferably 1 layer.
The composition and components of the adhesive composition constituting the 2 nd adhesive layer 104, the type of the adhesive composition (whether or not it is an active energy ray-curable type, a thermosetting type, or the like), additives that can be incorporated in the adhesive composition, the method for producing the 2 nd adhesive layer, and the thickness of the 2 nd adhesive layer are the same as those shown in the description of the 1 st adhesive layer 102.
The 2 nd adhesive layer 104 may be different from the 1 st adhesive layer 102 in terms of the composition, the compounding ingredients, the thickness, and the like of the adhesive composition.
[ Back plate ]
As the back plate 105, a plate-like body that can transmit light, a component used in a general display device, or the like can be used.
The thickness of the back plate 105 may be, for example, 5 μm to 2000 μm, preferably 10 μm to 1000 μm, and more preferably 15 μm to 500 μm.
The plate-like body used for the back plate 105 may be composed of only 1 layer, or may be composed of 2 layers or more, and the plate-like body exemplified by the plate-like body described in the front plate 101 may be used.
Examples of the components used in a normal display device used for the back plate 105 include a spacer, a touch sensor panel, and an organic EL display element. Examples of the lamination order of the constituent elements in the display device include a front panel/circularly polarizing plate/spacer, a front panel/circularly polarizing plate/organic EL display device, a front panel/circularly polarizing plate/touch sensor panel/organic EL display element, a front panel/touch sensor panel/circularly polarizing plate/organic EL display element, and the like.
(touch sensor Panel)
The touch sensor panel is not limited as long as it is a sensor capable of detecting a touched position, and examples thereof include a resistive film type, a capacitive coupling type, a photo sensor type, an ultrasonic type, an electromagnetic induction coupling type, and a surface acoustic wave type. In view of low cost, a touch sensor panel using a resistive film system or a capacitive coupling system is preferable.
An example of a resistive touch sensor panel is composed of a pair of substrates disposed opposite to each other, an insulating spacer sandwiched between the pair of substrates, a transparent conductive film provided as a resistive film on the front surface of the inner side of each substrate, and a touch position detection circuit. In an image display device provided with a resistive film type touch sensor panel, if the surface of a front panel is touched, the opposing resistive film is shorted, and a current flows through the resistive film. The touch position detection circuit detects a change in voltage at this time, and thereby detects a touched position.
An example of a capacitive-coupling type touch sensor panel is composed of a substrate, a transparent electrode for detecting a position provided on the entire surface of the substrate, and a touch position detection circuit. In an image display device provided with a capacitive coupling type touch sensor panel, if the surface of the front panel is touched, at the point of touch, the transparent electrode is grounded via the capacitance of the human body. The touch position detection circuit detects the grounding of the transparent electrode, thereby detecting the touched position.
The thickness of the touch sensor panel may be, for example, 5 μm to 2000 μm or 5 μm to 100 μm.
[ phase-difference layer ]
The laminate 100 may further include 1 layer or 2 or more retardation layers. The retardation layer is typically disposed between the polarizer layer 103 and the back plate 105. The retardation layer may be laminated on the 1 st adhesive layer 102 and the 2 nd adhesive layer 104, or may be laminated on other layers (including other retardation layers) via a layer (hereinafter also referred to as a bonding layer) made of an adhesive or an adhesive other than these layers.
[ adhesive layer ]
The adhesive layer is a layer disposed between the 1 st adhesive layer 102 and the 2 nd adhesive layer 104, and is a layer made of an adhesive or an adhesive. The adhesive constituting the adhesive layer may be the same adhesive as exemplified for the adhesive composition constituting the 1 st adhesive layer 102 or the 2 nd adhesive layer, or may be other adhesives such as (meth) acrylic adhesives, styrene adhesives, silicone adhesives, rubber adhesives, urethane adhesives, polyester adhesives, epoxy copolymer adhesives, and the like.
The adhesive constituting the adhesive layer may be formed by combining 1 or 2 or more kinds of aqueous adhesives, active energy ray-curable adhesives, and the like, for example. Examples of the aqueous adhesive include an aqueous polyvinyl alcohol resin solution and an aqueous two-part urethane emulsion adhesive. The active energy ray-curable adhesive is an adhesive cured by irradiation with active energy rays such as ultraviolet rays, and examples thereof include adhesives containing a polymerizable compound and a photopolymerization initiator, adhesives containing a photoreactive resin, adhesives containing a binder resin and a photoreactive crosslinking agent, and the like. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers, and photocurable urethane monomers, and oligomers derived from these monomers. Examples of the photopolymerization initiator include those containing active species such as neutral radicals, anionic radicals, and cationic radicals generated by irradiation with active energy rays such as ultraviolet rays.
The thickness of the bonding layer may be, for example, 1 μm or more, preferably 1 μm to 25 μm, more preferably 2 μm to 15 μm, and still more preferably 2.5 μm to 5 μm.
The laminate 200 shown in fig. 2 includes a front plate 101, a 1 st adhesive layer 102, a polarizer layer 103, a bonding layer 108, and a back plate 105, and further includes a 1 st retardation layer 106, a bonding layer 109, a 2 nd retardation layer 107, and a 2 nd adhesive layer 104.
Examples of the retardation layer include positive a plates such as λ/4 plates and λ/2 plates, and positive C plates.
The retardation layer may be, for example, a retardation film that can be formed of the thermoplastic resin film described above, or a layer obtained by curing a polymerizable liquid crystal compound, that is, a layer containing a cured product of a polymerizable liquid crystal compound, but the latter is preferable.
The thickness of the retardation film may be the same as that of the thermoplastic resin film described above. The thickness of the retardation layer obtained by curing the polymerizable liquid crystal compound is, for example, 0.1 μm to 10. Mu.m, preferably 0.5 μm to 8. Mu.m, more preferably 1 μm to 6. Mu.m.
The retardation layer obtained by curing the polymerizable liquid crystal compound can be formed by applying a composition containing the polymerizable liquid crystal compound to a base film and curing the composition. An alignment layer may be formed between the substrate film and the coating layer. The material and thickness of the base film may be the same as those of the thermoplastic resin film described above.
The retardation layer obtained by curing the polymerizable liquid crystal compound may be incorporated into the laminate 100 in the form of an alignment layer and/or a base film. The back panel 105 may be a substrate film coated with the above composition.
As described above, the adhesive layer 108 may be an adhesive or an adhesive. The adhesive may be the adhesive composition a described above.
As the adhesive, an aqueous adhesive or an active energy ray-curable adhesive can be used. Examples of the aqueous adhesive include an adhesive composed of an aqueous polyvinyl alcohol resin solution, an aqueous two-part urethane emulsion adhesive, and the like.
The active energy ray-curable adhesive is an adhesive cured by irradiation with active energy rays such as ultraviolet rays, and examples thereof include adhesives containing a polymerizable compound and a photopolymerization initiator, adhesives containing a photoreactive resin, adhesives containing a binder resin and a photoreactive crosslinking agent, and the like.
Examples of the polymerizable compound include a photopolymerizable monomer such as a photocurable epoxy monomer, a photocurable (meth) acrylic monomer, and a photocurable urethane monomer, and an oligomer derived from the photopolymerizable monomer.
The photopolymerization initiator includes those containing active species such as neutral radicals, anionic radicals, and cationic radicals generated by irradiation with active energy rays such as ultraviolet rays. As the active energy ray-curable adhesive containing a polymerizable compound and a photopolymerization initiator, an active energy ray-curable adhesive containing a photocurable epoxy monomer and a photocationic polymerization initiator can be preferably used.
[ method for producing laminate ]
The laminate 100 can be manufactured by a method including a step of bonding layers constituting the laminate 100 to each other via an adhesive layer or further via an adhesive layer. When the layers are bonded to each other via the pressure-sensitive adhesive layer and the adhesive layer, one or both of the bonding surfaces is/are preferably subjected to a surface activation treatment such as corona treatment in order to improve adhesion.
The polarizer layer 103 may be directly formed on a thermoplastic resin film or a base film, which may be incorporated in the laminate 100, or may be peeled off from the polarizer layer 103 without being a constituent of the laminate.
< display device >)
The display device of the present invention includes the laminate 100 of the present invention described above. The display device is not particularly limited, and examples thereof include image display devices such as organic EL display devices, inorganic EL display devices, liquid crystal display devices, and electroluminescent display devices. The display device may have a touch panel function. The optical laminate is suitable for a display device having flexibility, such as being bendable or bendable.
In the display device, the optical laminate is arranged such that the front panel faces outward (i.e., on the side opposite to the display element side, i.e., on the viewing side) on the viewing side of the display element included in the display device.
The display device of the invention can be used as mobile devices such as smart phones, tablet computers and the like, televisions, digital photo frames, electronic labels, measuring devices, instruments, office equipment, medical equipment, computer equipment and the like.
< adhesive composition >
The adhesive composition of the present invention is preferably the adhesive composition a described above. The adhesive composition of the present invention can be produced by mixing the components together by a known method, for example, using a mixer or the like.
< adhesive sheet >
The adhesive sheet of the present invention preferably comprises an adhesive layer formed of the adhesive composition a. The adhesive layer may be formed by coating the adhesive composition on the substrate. When the active energy ray-curable adhesive composition is used as the adhesive composition, a cured product having a desired degree of cure can be produced by irradiating the formed adhesive layer with active energy rays. When the thermosetting adhesive composition is used as the adhesive composition, the formed adhesive layer can be subjected to heat treatment (and curing) to produce a cured product having a desired degree of cure.
The substrate may be a release film subjected to a release treatment. The pressure-sensitive adhesive sheet can be produced by forming a layer of a pressure-sensitive adhesive on a release film in advance in a sheet form, and further laminating another release film on the pressure-sensitive adhesive layer.
The adhesive layer of the adhesive sheet of the present invention has excellent adhesive durability under the environment. The shear recovery rate at 25℃of a 200 μm thick reference adhesive layer formed from an adhesive composition used for the formation of the adhesive layer was defined as R 0 [％]In this case, the following relational expression (4) is preferably satisfied:
5≤R 0 ≤50 (4)，
more preferably, the following relational expression (4 a) is satisfied:
10≤R 0 ≤45 (4a)。
the present invention will be described in further detail with reference to examples, but the present invention is not limited to these examples.
Examples
[ adhesive sheet Using Heat-curable adhesive composition ]
[1] Production of adhesive sheet A11
(1) Preparation of (meth) acrylic polymers
54 parts by mass of n-butyl acrylate, 45 parts by mass of 2-ethylhexyl acrylate and 1 part by mass of 4-hydroxybutyl acrylate were copolymerized to prepare a (meth) acrylic polymer. The molecular weight of the (meth) acrylic polymer was measured by a method described later, and as a result, the weight average molecular weight (Mw) was 80 ten thousand.
(2) Preparation of adhesive composition
100 parts by mass (solid content equivalent; the same applies hereinafter) of the (meth) acrylic polymer obtained in the above-described step, 0.25 part by mass of trimethylolpropane-modified xylylene diisocyanate (product name "TD-75" manufactured by Zodiac chemical Co., ltd.) as a thermal crosslinking agent, and 0.2 part by mass of 3-glycidoxypropyl trimethoxysilane (product name "KBM403" manufactured by Xinyue chemical Co., ltd.) as a silane coupling agent were mixed and stirred thoroughly, and diluted with methyl ethyl ketone, whereby a coating solution of the adhesive composition was obtained. Table 1 shows the respective blends (solid content conversion values) of the adhesive composition when 100 parts by mass (solid content conversion values) of the (meth) acrylic polymer were used. The abbreviations and the like described in table 1 indicate the following meanings.
BA: acrylic acid n-butyl ester
2EHA: 2-ethylhexyl acrylate
4HBA: acrylic acid 4-hydroxybutyl ester
(3) Production of adhesive sheet A11
The resulting coating solution of the adhesive composition was applied to the release treated surface of a light separator (manufactured by Lintec Corporation, product name "SP-PET 752150") by a knife coater. Then, the coating layer was subjected to a heat treatment at 90 ℃ for 1 minute to form a coating layer. Next, the coating layer on the light separator and the heavy separator (manufactured by Lintec Corporation, product name "SP-PET 382120") obtained above were bonded so that the release treated surface of the separator was in contact with the coating layer, and cured under conditions of 23 ℃ and 50% rh for 7 days, thereby producing an adhesive sheet a11 having an adhesive layer with a thickness of 25 μm, that is, an adhesive sheet a11 composed of a structure of light separator/adhesive layer (thickness: 25 μm)/heavy separator. The adhesive layer of the adhesive sheet a11 was used as the adhesive layer a11. The shear recovery rate measured for the adhesive sheet a11 is shown in table 1. The thickness and shear recovery rate of the adhesive layer a11 were measured by the method described later.
[2] Production of pressure-sensitive adhesive sheets A12 to A16
(1) Preparation of (meth) acrylic polymers
The proportions of the monomers constituting the (meth) acrylic polymer shown in table 1 were determined in the same manner as in the production process of the adhesive sheet a11, and the (meth) acrylic polymer having the weight average molecular weight (Mw) shown in table 1 was produced.
(2) Preparation of adhesive composition
100 parts by mass of the (meth) acrylic polymer obtained in the above-described step, trimethylolpropane-modified xylylene diisocyanate (product name "TD-75" manufactured by Son chemical Co., ltd.) as a thermal crosslinking agent, and 3-glycidoxypropyl trimethoxysilane (product name "KBM403" manufactured by Son chemical Co., ltd.) as a silane coupling agent were mixed in the mixing ratio shown in Table 1, and the mixture was sufficiently stirred and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition.
(3) Production of pressure-sensitive adhesive sheets A12 to A16
The adhesive sheets a12 to a16 were produced in the same manner as the production process of the adhesive sheet a11 using the coating solution of the obtained adhesive composition. The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets a12 to a16 were used as the pressure-sensitive adhesive layers a12 to a16. The thicknesses and shear recovery rates of the pressure-sensitive adhesive layers a12 to a16 measured by the method described later are shown in table 1.
TABLE 1
[ adhesive sheet Using active energy ray-curable adhesive composition ]
[1] Production of adhesive sheet A21
(1) Preparation of (meth) acrylic Polymer A21
A monomer mixture composed of 97.9 mass% of 2-ethylhexyl acrylate (2-EHA) monomer and 2 mass% of Butyl Acrylate (BA) monomer was charged into a 1L reactor equipped with a cooling device for refluxing nitrogen gas to easily adjust the temperature, and then, the nitrogen gas was refluxed for 1 hour to remove oxygen, and then, maintained at 80 ℃. After the monomer mixture was uniformly mixed, 0.05 mass% of benzildimethylketal (I-651) and 0.05 mass% of 1-hydroxycyclohexyl phenyl ketone (I-184) were charged as photopolymerization initiators. Subsequently, a UV lamp (10 mW) was irradiated while stirring, and a (meth) acrylic polymer a21 having a weight average molecular weight (mW) of 46 ten thousand was produced.
The ratio of each monomer to each component of the acrylic polymer a21 is shown in table 2. Abbreviations and the like described in table 2 indicate the following meanings.
2-EHA: 2-ethylhexyl acrylate (Tokyo chemical industry Co., ltd., japan),
BA: butyl acrylate (tokyo chemical industry Co., ltd., japan),
2-HEA: 2-hydroxyethyl acrylate (Tokyo chemical industry Co., ltd., japan),
LA: lauryl acrylate (tokyo chemical industry co., japan),
i-651: benzil dimethyl ketal (photopolymerization initiator, BASF, germany),
i-184: 1-hydroxycyclohexyl phenyl ketone (photopolymerization initiator, BASF, germany).
(2) Preparation of adhesive composition
The (meth) acrylic polymer obtained in the above step was mixed with 95 mass% (solid content equivalent; hereinafter the same), 1 mass% of isodecyl acrylate (IDA, miwon specialty chemical, korea) as an additive, 3 mass% of aliphatic monofunctional urethane acrylate (MU 9001, miramer MU9001, miwon specialty chemical, korea), 0.5 mass% of diphenyl (2, 4, 6-trimethylbenzoyl) phosphine oxide (TPO, tokyo chemical industry co., japan) as a photopolymerization initiator, and 0.5 mass% of 1-hydroxycyclohexyl phenyl ketone (I-184, basf, germany) as a photopolymerization initiator, and stirred thoroughly, to thereby obtain a coating solution of the adhesive composition. Table 3 shows the blending (solid content conversion value) of each adhesive composition. Abbreviations and the like described in table 3 indicate the following meanings.
IDA: isodecyl acrylate (Miwon specialty chemical, korea)
MU9001: aliphatic monofunctional urethane acrylates (Miramer MU9001, miwon specialty chemical, korea)
TPO: diphenyl (2, 4, 6-trimethylbenzoyl) phosphine oxide (tokyo chemical industry Co., ltd., japan)
I-184: 1-hydroxycyclohexyl phenyl ketone (BASF, germany)
(3) Production of adhesive sheet A21
The coating solution of the obtained adhesive composition was applied to the release treated surface of a light separator (polyethylene terephthalate film, thickness 38 μm) with a blade coater. Next, the coating layer on the light separator and the heavy separator (polyethylene terephthalate film, thickness 38 μm) obtained above were bonded so that the release treated surface of the separator was in contact with the coating layer, and UV irradiation was performed to prepare an adhesive sheet a21 having an adhesive layer with a thickness of 25 μm, that is, an adhesive sheet a21 composed of a light separator/adhesive layer (thickness: 25 μm)/heavy separator structure. The adhesive layer of the adhesive sheet a21 was used as the adhesive layer a21. The shear recovery rate measured for the adhesive sheet a21 is shown in table 3. The thickness and shear recovery rate of the adhesive layer a21 were measured by the method described later.
[2] Production of pressure-sensitive adhesive sheets A22, A23
(1) Preparation of (meth) acrylic polymers A22, A23
The proportions of the monomers constituting the (meth) acrylic polymer were prepared as shown in table 2, and the (meth) acrylic polymers a22 and a23 having weight average molecular weights (Mw) shown in table 2 were prepared in the same manner as the production process of the adhesive sheet a 21.
(2) Preparation of adhesive composition
The (meth) acrylic polymer obtained in the above step and the additive were mixed in the mixing ratio shown in table 3, and the mixture was sufficiently stirred and diluted with methyl ethyl ketone to obtain a coating solution of the adhesive composition.
(3) Production of pressure-sensitive adhesive sheets A22, A23
The adhesive sheets a22 and a23 were produced in the same manner as the production process of the adhesive sheet a21 using the coating solution of the obtained adhesive composition. The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets a22 and a23 were used as the pressure-sensitive adhesive layers a22 and a23. The thicknesses and shear recovery rates of the pressure-sensitive adhesive layers a22 and a23 measured by the methods described later are shown in table 3 for the pressure-sensitive adhesive sheets a22 and a23.
TABLE 2
TABLE 3
< determination of weight average molecular weight (Mw) >)
The weight average molecular weight (Mw) of the (meth) acrylic polymer was determined by Size Exclusion Chromatography (SEC) described below using tetrahydrofuran as the mobile phase, as the number average molecular weight (Mn) in terms of polystyrene.
The measured (meth) acrylic polymer was dissolved in tetrahydrofuran at a concentration of about 0.05 mass%, and 10. Mu.L was injected into SEC. The mobile phase was flowed at a flow rate of 1.0 mL/min. The column used was PLgel MIXED-B (manufactured by Polymer Laboratories). The detector used was a UV-VIS detector (trade name: agilent GPC).
< thickness of layer >
The measurement was performed using a contact film thickness measuring apparatus (MS-5C, nikon Co., ltd.).
Among them, the polarizer layer and the alignment film were measured using a laser microscope (OlS 3000 manufactured by Olympic Co., ltd.).
< shear recovery Rate >)
Shear recovery was measured using a viscoelasticity measuring device (MCR-301, anton Paar Co.). The pressure-sensitive adhesive sheet was cut into pieces having a width of 20mm and a length of 20mm, and the release film was peeled off, and 8 pieces of the pressure-sensitive adhesive sheet were laminated to a thickness of 200 μm and bonded to a glass plate. The measurement was performed at 25℃under conditions of a Normal force (Normal force) of 1N and a Torque (Torque) of 1200. Mu.Nm in a state of being bonded to the measurement chip, and after measuring the shear deformation amount for 1200 seconds, the measurement was continued under conditions of changing to a Torque of 0. Mu.Nm, and the shear deformation amount for 1206 seconds was measured. Based on these measured values, the shear recovery rate R is calculated from the following formula 0 。
R 0 = (1200 seconds shear deformation amount-1206 seconds shear deformation amount)/1200 seconds shear deformation amount x 100[%]
Front panel (Window film)
As the front panel, a polyimide film (thickness 50 μm) having a hard coat layer (thickness 10 μm) on one side was prepared.
[ polarizer layer ]
1. The following materials were prepared.
1) TAC film with thickness of 25 μm.
2) Composition for forming an alignment film.
< Polymer 1 >)
A polymer 1 having a photoreactive group constituted of the following structural units was prepared.
A solution in which polymer 1 was dissolved in cyclopentanone at a concentration of 5 mass% was used as the composition for forming an alignment film [ hereinafter, also referred to as composition (D-1) ].
3) Composition for forming polarizer layer
< polymerizable liquid Crystal Compound >
The polymerizable liquid crystal compound represented by the formula (1-1) [ hereinafter also referred to as compound (1-1) ] and the polymerizable liquid crystal compound represented by the formula (1-2) [ hereinafter also referred to as compound (1-2) ].
Compound (1-1) and compound (1-2) were synthesized by the method described in Lub et al, recl. Trav. Chim. Pays-Bas,115, 321-328 (1996).
< dichroic dye >)
As the dichroic dye, an azo dye described in examples of Japanese patent application laid-open No. 2013-101328 represented by the following formulas (2-1 a), (2-1 b) and (2-3 a) is used.
/>
The composition for forming a polarizer layer [ hereinafter, also referred to as composition (a-1) ] was prepared by mixing 75 parts by mass of compound (1-1), 25 parts by mass of compound (1-2), 2.5 parts by mass of each of the azo pigments represented by the above-mentioned formulas (2-1 a), (2-1 b) and (2-3 a) as dichroic dyes, 6 parts by mass of 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butane-1-one (Irgacure 369, manufactured by BASF Japan) as a polymerization initiator, and 1.2 parts by mass of a polyacrylate compound (BYK-361 n, manufactured by BYK-Chemie) as a leveling agent in 400 parts by mass of toluene as a solvent, and stirring the resultant mixture at 80 ℃ for 1 hour.
4) Composition for forming protective layer (OC layer)
Composition for forming protective layer (OC layer) [ hereinafter, also referred to as composition (E-1) ] is prepared by mixing water: 100 parts by mass of a polyvinyl alcohol resin powder (manufactured by Kuraray Co., ltd., average polymerization degree 18000, trade name: KL-318): 3 parts by mass of a polyamide epoxy resin (crosslinking agent, trade name: SR650 (30)) manufactured by Sumika Chemtex Co., ltd.): 1.5 parts by mass.
2. Manufacturing method
1) The composition for forming an alignment film was applied to the TAC film side as follows.
First, the TAC film side was subjected to corona treatment 1 time. The conditions for the corona treatment were 0.3kW output and a treatment speed of 3 m/min. Thereafter, the composition (D-1) obtained above was coated on the TAC by a bar coating method, and dried by heating in a drying oven at 80℃for 1 minute. The obtained dried film was subjected to a polarized UV irradiation treatment to form a 1 st alignment film (AL 1). The polarized light UV treatment was performed by passing light irradiated from a UV irradiation apparatus (SPOTCURE SP-7; manufactured by Ushio Electric Co., ltd.) through a wire grid (UIS-27132 #, manufactured by Ushio Electric Co., ltd.) and measuring the cumulative light quantity at a wavelength of 365nm at 100mJ/cm 2 Is carried out under the condition of (2). The 1 st alignment film (AL 1) has a thickness of 100nm.
2) The composition for forming the polarizer layer was applied to the alignment film side as follows.
The composition (A-1) was first applied to the 1 st orientation film (AL 1) formed by the bar coating method, and after drying by heating in a drying oven at 120℃for 1 minute, it was cooled to room temperature. Using the above UV irradiation apparatus to accumulate a light quantity of 1200mJ/cm 2 Ultraviolet rays were irradiated to the dried film (365 nm basis), thereby forming a polarizer layer (pol). The thickness of the polarizer layer (pol) was measured by a laser microscope (OLS 3000, olympic Co., ltd.) and found to be 1.8. Mu.m. Thus, a laminate composed of "TAC/AL1/pol" was obtained.
3) The composition for forming the protective layer (OC layer) was applied to the polarizer layer side as follows.
The composition (E-1) was applied to the polarizer layer (pol) formed by the bar coating method, and the composition was dried at 80℃for 3 minutes so that the thickness of the composition after drying was 1.0. Mu.m. Thus, a laminate composed of "TAC film/cPL (Al1+pol+protective layer)" was obtained.
[ phase-difference layer ]
1. Material preparation
The following materials were prepared.
1) A PET film having a thickness of 100 μm.
2) Composition for forming an alignment film.
< Polymer 1 >)
A polymer 1 having a photoreactive group constituted of the following structural units was prepared.
A solution in which polymer 1 was dissolved in cyclopentanone at a concentration of 5 mass% was used as the composition for forming an alignment film [ hereinafter, also referred to as composition (D-1) ].
3) Composition for forming retardation layer
The following components were mixed, and the resulting mixture was stirred at 80℃for 1 hour, thereby obtaining a composition (B-1).
A compound b-1 represented by the following formula: 80 parts by mass
A compound b-2 represented by the following formula: 20 parts by mass
Polymerization initiator (Irgacure 369, 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) butan-1-one, manufactured by BASF Japan Co., ltd.): 6 parts by mass
Leveling agent (BYK-361N, polyacrylate Compound, BYK-Chemie): 0.1 part by mass
Solvent (cyclopentanone): 400 parts by mass
2. Manufacturing method
1) The composition for forming an alignment film was applied to a PET film as follows.
A polyethylene terephthalate film (PET) having a thickness of 100 μm was prepared as a base material, and the composition (D-1) was applied to the film by a bar coating method, and dried by heating in a drying oven at 80℃for 1 minute. Subjecting the obtained dried film to UV irradiation treatment with polarized light to formForming a 2 nd orientation film (AL 2). The polarized light UV treatment was carried out by using the above UV irradiation apparatus, and the cumulative light amount measured at 365nm wavelength was 100mJ/cm 2 Is carried out under the condition of (2). The polarization direction of the polarized light UV was 45 ° with respect to the absorption axis of the polarizer layer. Thus, a laminate composed of "substrate (PET)/2 nd orientation film (AL 2)" was obtained.
2) The composition for forming the retardation layer was applied to the alignment film side of the PET film as follows.
The composition (B-1) was applied to the 2 nd orientation film (AL 2) of the 1 st substrate thus obtained by the bar coating method, and the resultant was dried by heating in a drying oven at 120℃for 1 minute, and then cooled to room temperature. The obtained dried film was irradiated with the accumulated light of 1000mJ/cm using the above UV irradiation apparatus 2 Ultraviolet rays (365 nm basis), thereby forming a retardation layer. The thickness of the retardation layer was measured by a laser microscope (OLS 3000, olympic Co., ltd.) and found to be 2.0. Mu.m. The retardation layer is a lambda/4 plate (QWP) exhibiting a retardation value of lambda/4 in the in-plane direction. Thus, a laminate composed of "substrate (PET)/AL 2/QWP" was obtained.
[ common adhesive sheet ]
1) Polymerization of acrylic resins
The following components were reacted at 55℃while stirring them under a nitrogen atmosphere to obtain an acrylic resin.
Butyl acrylate: 70 parts by mass
Methyl acrylate: 20 parts by mass
Acrylic acid: 2.0 parts by mass
Radical polymerization initiator (2, 2' -azobisisobutyronitrile): 0.2 part by mass
2) Liquid conditioning of adhesive composition
The following ingredients were mixed to obtain an adhesive composition.
Acrylic resin: 100 parts by mass
Crosslinking agent (Coronate L, tosoh Co.): 1.0 part by mass
Silane coupling agent (Xinyue silicon Co., ltd. "X-12-981"): 0.5 part by mass
Ethyl acetate was added so that the total solid content concentration was 10 mass%, to obtain an adhesive composition.
3) Production of adhesive sheet
The obtained adhesive composition was applied to the release treated surface of a release treated polyethylene terephthalate film (heavy separator, thickness 38 μm) with an applicator so that the thickness after drying was 5 μm. The coating layer was dried at 100℃for 1 minute to obtain a film having an adhesive layer. Thereafter, another polyethylene terephthalate film (light separator, thickness 38 μm) subjected to release treatment was laminated on the exposed surface of the adhesive layer. Thereafter, the mixture was cured at a temperature of 23℃and a relative humidity of 50% RH for 7 days to obtain a light separator/common adhesive layer/heavy separator.
Example 1
A laminate was produced in the order shown in fig. 4 (a) to (e). First, a laminate 410 including the above-described polarizer layer [ tac film 301/cPL ((al1+pol) 302/OC layer 303) ] and the above-described common adhesive sheet 420 (light separator 304/common adhesive layer 305/heavy separator 306) ] are prepared (fig. 4 (a)). The OC layer 303 side of the laminate 410 including the polarizer layer and the surface of the common pressure-sensitive adhesive sheet 420 from which the light separator 304 was peeled were subjected to corona treatment (output 0.3KW, speed 3 m/min), and then bonded to each other, to obtain a laminate a430. The retardation layer 440 described above [ substrate (PET) 308/AL2/QWP307] was prepared. (fig. 4 (b)).
Next, the QWP307 side of the retardation layer 440 and the surface of the laminate a430 from which the heavy separator 306 was peeled were subjected to corona treatment (output 0.3KW, speed 3 m/min), and then bonded to obtain a laminate b450. Thereafter, the adhesive sheet a11 produced as described above was prepared as the adhesive sheet 460 (light separator 309/adhesive layer 310/heavy separator 311) (fig. 4 (c)). The adhesive layer 310 of the adhesive sheet 460 corresponds to the 2 nd adhesive layer.
After corona treatment (output of 0.3KW, speed of 3 m/min) was applied to the surface of laminate b450 from which base material (PET) 308 was peeled off and the surface of adhesive sheet 460 from which light separator 309 was peeled off, lamination was performed to obtain laminate c470. Then, the adhesive sheet a12 thus produced was prepared as an adhesive sheet 490 (light separator 314/adhesive layer 315/heavy separator 316), and the surface from which the light separator 314 was peeled off and the polyimide film 313 side of the front panel 480 (polyimide film 313/hard coat layer 312) were subjected to corona treatment (output 0.3KW, speed 3 m/min), and then bonded to obtain a laminate d500 (fig. 4 (d)). The adhesive layer 315 of the adhesive sheet 490 corresponds to the 1 st adhesive layer.
The surface of laminate d500 from which heavy separator 316 was peeled off and TAC301 side of laminate c470 were subjected to corona treatment (output 0.3KW, speed 3 m/min), and then laminated to obtain laminate 300 of example 1 (fig. 4 (e)). The laminate of example 1 was evaluated for normal temperature bendability and normal temperature adhesion durability by the method described below. The results are shown in Table 4.
Examples 2 to 6 and comparative examples 1 and 2
Laminates of examples 2 to 6 and comparative examples 1 and 2 were produced in the same manner as in example 1, except that the adhesive sheets a12 and a11 were replaced with the adhesive sheets having the adhesive layers shown in table 4 in example 1. The laminates of examples 2 to 6 and comparative examples 1 and 2 were evaluated for normal temperature bendability and normal temperature adhesion durability by the method described below. The results are shown in Table 4.
< bending at Normal temperature >
The laminate obtained in each example and each comparative example was subjected to an evaluation test for confirming normal temperature flexibility using a bending apparatus (STS-VRT-500, manufactured by Science Town Co.).
The heavy separator 311 was peeled off and bonded to a PET film having a thickness of 100 μm to obtain a laminate. The PET film corresponds to the back plate. Fig. 3 is a diagram schematically showing a method of the evaluation test. As shown in fig. 3, 2 tables 501 and 502 capable of moving independently are arranged so that the gap C is 6.0mm (3R), and the laminate is fixedly arranged so that the center in the width direction is positioned at the center of the gap C and the hard coat layer 312 is positioned at the lower side (fig. 3 a). Then, the 2 tables 501 and 502 are rotated upward by 90 degrees about the center of the rotation axis at positions P1 and P2, and bending force is applied to the region of the laminate corresponding to the gap C between the tables (bending force for bringing the front panel 480 to the outside) (fig. 3 (b)). Thereafter, the 2 mounting tables 501 and 502 are returned to the original positions (fig. 3 (a)). The above series of operations was completed, and the number of times of application of the bending force was counted as 1. After repeating this at a temperature of 25 ℃, it was confirmed whether or not air bubbles were generated in the adhesive layer in the region corresponding to the gap C between the stages 501 and 502 of the laminate. The movement speed of the tables 501 and 502 and the bending force application step were the same conditions in the evaluation test for each laminate. The "adhesive peeling" means that the adhesive layer oozes out from the end portion of the laminate.
A: no bubbles were generated even when the bending force was applied 10 ten thousand times.
B: the number of times of application of the bending force is 5 ten thousand or more and less than 10 ten thousand, and bubbles are generated.
C: the number of times of application of the bending force is 2 ten thousand or more and less than 5 ten thousand, and bubbles are generated.
D: the number of times of application of the bending force is 1 ten thousand or more and less than 2 ten thousand, and bubbles are generated.
E: the number of bending force applications is less than 1 ten thousand times to generate bubbles/adhesive shedding.
< room temperature adhesion durability >)
The laminate obtained in each example and each comparative example was cut into a width of 100mm×a length of 100mm. The heavy separator 311 was peeled off and bonded to alkali-free glass. The pressure-bonding treatment was performed in an autoclave (50 ℃ C., 5 atm) for about 20 minutes, and the pressure-bonding treatment was maintained under constant temperature and humidity conditions (23 ℃ C., 50% RH) for 4 hours. The sample was placed in an oven at 25℃for 250 hours and then judged to be floating, peeling, and air bubbles. The alkali-free glass in the laminated body corresponds to the back plate.
O: there was little change in appearance such as floating, flaking, foaming, etc.
Delta: the appearance changes such as floating, flaking, foaming, etc. are slightly noticeable.
X: the appearance changes of floating, flaking, foaming and the like are obvious.
TABLE 4
Examples 1 to 6 satisfy "R 0 1≤R 0 2", and the 1 st adhesive layer and the 2 nd adhesive layer have the same thickness, it can be determined that the relationship of" R1. Ltoreq.R2 "is satisfied. On the other hand, comparative examples 1 and 2 were "R 0 1＞R 0 2", the thickness of the 1 st adhesive layer and the 2 nd adhesive layer are the same, and thus it can be judged that" R1 > R2 ".
Symbol description
100. 200 laminated body, 101 front panel, 102 1 st adhesive layer, 103 polarizer layer, 104 nd adhesive layer, 105 back panel, 106 1 st phase difference layer, 107 nd phase difference layer, 108, 109 lamination layer, 301TAC film, 302pol,303oc layer, 305 common adhesive layer, 306, 311, 316 heavy separator, 307qwp,308 base material, 304, 309, 314 light separator, 310, 315 adhesive layer, 312 hard coat layer, 313 polyimide film, 410 laminated body including polarizer layer, 420 common adhesive sheet, 430 laminated body a,440 phase difference layer, 450 laminated body b,460, 490 adhesive sheet, 470 laminated body c,500 laminated body d,501, 502 mounting table.

Claims (5)

1. A flexible laminate comprising, in order, a front panel, a 1 st adhesive layer formed using a 1 st adhesive composition, a polarizer layer, a 2 nd adhesive layer formed using a 2 nd adhesive composition, and a back panel,
if the shear recovery rate of the 1 st adhesive layer at 25 ℃ is set to be R1[% ], and the shear recovery rate of the 2 nd adhesive layer at 25 ℃ is set to be R2[% ], the following relational expression (1') is satisfied:
R1＜R2(1’)
If the shear recovery rate at 25℃of the 1 st reference adhesive layer having a thickness of 200 μm formed using the 1 st adhesive composition is set to R 0 1[％]The shear recovery rate at 25℃of a 2 nd reference adhesive layer having a thickness of 200 μm formed using the 2 nd adhesive composition was defined as R 0 2[％]The following relationships (2) and (3) are satisfied:
5≤R 0 1≤30 (2)
33≤R 0 2≤50 (3)。
2. the flexible laminate according to claim 1, wherein the 1 st adhesive layer and the 2 nd adhesive layer each contain a (meth) acrylic polymer,
the weight average molecular weight (Mw) of the (meth) acrylic polymer is 20 to 150 ten thousand.
3. The flexible laminate according to claim 1 or 2, wherein a retardation layer of 1 layer or more is provided between the polarizer layer and the back plate.
4. A flexible laminate according to any one of claims 1 to 3, wherein the back panel is a touch sensor panel.
5. A display device comprising the flexible laminate of any one of claims 1 to 4.
CN202080016727.2A 2019-02-27 2020-02-07 flexible laminate Active CN113474702B (en)

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