JP2022093347A - Adhesive sheet, adhesive component, flexible image display device member, laminate and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel adhesive sheet which can strongly adhere to a member sheet having high polarity, has transparency and is also excellent in flexibility.

SOLUTION: There is provided an adhesive sheet which contains an adhesive having a urethane polymer chain having a polyether polyol component and a molecular chain having a urethane bond derived from an isocyanate component and an acrylic polymer chain having a molecular chain derived from an alkyl (meth)acrylate ester component, wherein (I) the storage elastic modulus at -20°C (G'(-20°C)) obtained by the dynamic viscoelasticity measurement in the shear mode at a frequency of 1 Hz is 300 kPa or less and (II) the storage elastic modulus at 60°C (G'(60°C)) obtained by the dynamic viscoelasticity measurement in the shear mode at a frequency of 1 Hz is 10 kPa or more.

SELECTED DRAWING: None

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to an adhesive sheet, a flexible image display device member, an adhesive component, a laminate, and an image display device. More specifically, the present invention uses an adhesive sheet, an adhesive layer, or an adhesive component that is suitably used for a bendable image display device and can firmly adhere to a member sheet constituting the image display device. It relates to a laminate, a flexible image display device member, or an image display device, and contributes to improving the reliability of a bendable image display device.

In recent years, flexible or bendable image display devices using organic light emitting diodes (OLEDs) and quantum dots (QDs) have been developed and are being widely commercialized.
In such an image display device, a plurality of member sheets are bonded together with a transparent adhesive sheet, and the member sheet is firmly held while having softness capable of absorbing distortion between the member sheets due to bending. There is a demand for an adhesive sheet that can be adhered.

The pressure-sensitive adhesive sheet widely used in conventional image display devices has been an acid-free acrylic pressure-sensitive adhesive sheet that does not substantially contain acid.
In recent years, a pressure-sensitive adhesive sheet having a low Tg (glass transition temperature), in which the acrylic polymer composition has been reviewed in order to correspond to an image display device for bending, has been proposed.

For example, Patent Document 1 discloses a pressure-sensitive adhesive containing a (meth) acrylic acid ester copolymer and a cross-linking agent, having a predetermined creep compliance value, and having improved stability.

Further, Patent Document 2 describes an assembly layer for a flexible device containing an adhesive composition, wherein the assembly layer has a frequency of about 2 MPa at a frequency of 1 Hz within a temperature range of about −30 ° C. to about 90 ° C. Shear storage elasticity not exceeding, and shear creep compliance (J) of at least about 6 × ^10-6 1 / Pa measured in 5 seconds with a shear stress of about 50 kPa to about 500 kPa, and about 5 kPa to about. An assembly layer is disclosed that has at least about 50% strain recovery within about 1 minute after release of the applied shear stress at at least one point loaded with shear stress within the range of 500 kPa.

Further, Patent Document 3 describes a laminated body for a flexible image display device including an adhesive layer and an optical film including at least a polarizing film, and the laminated body when the laminated body is bent with a bending radius of 3 mm. A laminate for a flexible image display device is disclosed, wherein the amount of deviation based on the pressure-sensitive adhesive layer at the end of the film is 100 to 600 μm.

Japanese Unexamined Patent Publication No. 2019-1238226 Japanese Patent Publication No. 2018-526469 International Pamphlet WO2019 / 026753 Gazette

With the advent of bendable image display devices, member sheets used for them are also being used that are compatible with bending. For example, a transparent polyimide film has been adopted as a front cover film.
However, since such a polyimide film has high polarity, there is a risk that the conventional adhesive sheet may be peeled off due to the stress of bending, or the display user may mistakenly think that it is a part of the protective film and peel it off. there were.

In addition, the demand for thinner image display devices and smaller radius of curvature is expected to become stricter year by year, and it is predicted that the need for stronger adhesiveness for adhesive sheets will increase accordingly.

Therefore, according to the present invention, a new pressure-sensitive adhesive sheet, a pressure-sensitive adhesive layer, a pressure-sensitive adhesive component, which can firmly adhere to a highly polar member sheet or a flexible member, has transparency, and is also excellent in flexibility. Further, the present invention provides a laminate, a flexible image display device member, and an image display device using these.

The present invention comprises a urethane polymer chain (hereinafter, also referred to as "urethane component segment") having a molecular chain having a urethane bond derived from a polyether polyol component and an isocyanate component, and a molecular chain derived from a (meth) acrylic acid alkyl ester component. We propose a pressure-sensitive adhesive sheet containing an acrylic polymer chain (hereinafter, also referred to as “acrylic component segment”) and a pressure-sensitive adhesive, which satisfies the following (I) and (II).
(I) The storage elastic modulus (G'(-20 ° C.)) at −20 ° C. obtained by dynamic viscoelasticity measurement in a shear mode with a frequency of 1 Hz is 300 kPa or less.
(II) The storage elastic modulus (G'(60 ° C.)) at 60 ° C. obtained by dynamic viscoelasticity measurement in a shear mode with a frequency of 1 Hz is 10 kPa or more.

The present invention also proposes an adhesive component used in a flexible device, which comprises an adhesive having a urethane component segment and an acrylic component segment.

The present invention is also a flexible image display device member having a structure in which two flexible members are bonded to each other via an adhesive layer, and the adhesive layer is a molecular chain having a urethane bond derived from a polyether polyol component and an isocyanate component. It has a urethane polymer chain having a urethane polymer chain (hereinafter referred to as “urethane component segment”) and an acrylic polymer chain having a molecular chain derived from a (meth) acrylic acid alkyl ester component (hereinafter referred to as “acrylic component segment”). Contains adhesive,
The adhesive layer proposes a flexible image display device member that satisfies the following (I) and (II).
(I) The storage elastic modulus (G'(-20 ° C.)) at −20 ° C. obtained by dynamic viscoelasticity measurement in a shear mode with a frequency of 1 Hz is 300 kPa or less.
(II) The storage elastic modulus (G'(60 ° C.)) at 60 ° C. obtained by dynamic viscoelasticity measurement in a shear mode with a frequency of 1 Hz is 10 kPa or more.
The form of the adhesive layer is not limited, and the flexible image display device may be formed by bonding a sheet-shaped adhesive product previously molded into a sheet shape to the flexible image display device member. The adhesive layer may be directly formed on the member.

The present invention is also a laminate in which the member sheet is provided on at least one side of the pressure-sensitive adhesive sheet, and the Hansen solubility parameter δp on the surface of the member sheet is 10 MPa ^0.5 or more and 20 MPa ^0.5 or less. We propose a featured laminate and an image display device provided with the laminate.

The adhesive sheet or adhesive layer of the present invention exhibits a large adhesive force even with a highly polar member sheet or a flexible member, has transparency, and further, even when stored at a high temperature in a bent state, such as delamination and foaming. The occurrence of defects can be suppressed.
Therefore, it can be suitably used for a bendable image display device.

Hereinafter, the present invention will be described in detail. However, the content of the present invention is not limited to the embodiments described below.

<< This adhesive sheet >>
The pressure-sensitive adhesive sheet (hereinafter referred to as “the present pressure-sensitive adhesive sheet”) according to an example of the embodiment of the present invention is a urethane polymer chain having a molecular chain having a urethane bond derived from a polyether polyol component and an isocyanate component (hereinafter, “urethane”). A pressure-sensitive adhesive having a (referred to as "component segment") and an acrylic polymer chain having a molecular chain derived from a (meth) acrylic acid alkyl ester component (hereinafter referred to as "acrylic component segment") (hereinafter referred to as "this pressure-sensitive adhesive"). ) Includes.

<< This flexible image display device member >>
The flexible image display device member according to an example of the embodiment of the present invention (hereinafter, may be referred to as "the present flexible image display device member") has a configuration in which two flexible members are bonded to each other via an adhesive layer. The flexible image display device member, the adhesive layer (hereinafter, may be referred to as "the present adhesive layer") contains the present adhesive.

The acrylic component segment, that is, "an acrylic polymer chain having a molecular chain derived from a (meth) acrylic acid alkyl ester component" means a molecular chain structure in which a (meth) acrylic acid alkyl ester is continuously polymerized. The acrylic component segment is a segment having the molecular chain structure.
On the other hand, the urethane component segment, that is, the "urethane polymer chain having a molecular chain having a urethane bond derived from the polyether polyol component and the isocyanate component" is polymerized by forming a urethane bond by the reaction of the polyether polyol and the polyisocyanate. The urethane component segment is a segment having the molecular chain structure.

<This adhesive>
By containing the urethane component segment, this pressure-sensitive adhesive makes it possible to increase δp in the HSP on the surface as compared with the pressure-sensitive adhesive sheet or the pressure-sensitive adhesive layer made of only an acrylic polymer, as will be described later. Therefore, the wettability with various display films (member sheets) having a large δp is improved, the interfacial adhesive strength is improved, and as a result, it is possible to contribute to the improvement of the adhesive strength in the peeling test.

In the present adhesive sheet or the present adhesive layer, the acrylic component segment in the present adhesive preferably has a larger mass ratio than the urethane component segment. Above all, the mass of the urethane component segment is preferably 0.3 to 40 parts by mass with respect to 100 parts by mass of the acrylic component segment, and above all, 0.5 parts by mass or more or 30 parts by mass or less, and 1 part by mass among them. It is more preferably more than 20 parts by mass or less.

Examples of the urethane component segment generally include those having a polyether chain, a polyester chain, a polycarbonate chain, or the like.
However, in the present invention, from the viewpoint of compatibility with the acrylic component, it is preferable that the urethane component segment is a polyether type having a polyether chain.
The urethane component segment is formed of a polyol and a polyfunctional isocyanate compound, and the polyol is preferably a polyether polyol.
Further, among the polyether polyols, those containing a component derived from polyether glycol are preferably selected, and among them, the polyether glycol is preferably selected as the main component.

Here, the "main component" means the component having the highest mass ratio in the polyol, and preferably occupies 50% by mass or more in the polyol, particularly 70% by mass or more, and 80% by mass or more among them. Above all, it is preferable to occupy 90% by mass or more (including 100% by mass).

In the present adhesive sheet or the present adhesive layer, it is preferable that the acrylic component segment and the urethane component segment in the present adhesive are bonded by a covalent bond.

Further, the present pressure-sensitive adhesive preferably contains one or more of the following polymers (a) to (c).
Further, it is preferable that the acrylic component segment and the urethane component segment are covalently bonded. By including the polymer in which the acrylic component segment and the urethane component segment are covalently bonded, the acrylic component segment and the urethane component segment are easily compatible with each other, and the transparency of the present adhesive sheet or the present adhesive layer is improved.

(A) Block polymer in which both the urethane component segment and the acrylic component segment form the main chain (b) A graft in which the urethane component segment or the acrylic component segment constitutes the main chain and the other segment constitutes the side chain. Polymer (c) A crosslinked polymer in which one of the urethane component segment or the acrylic component segment and the other segment are crosslinked.

<First aspect>
Among the above, as a preferred embodiment of the pressure-sensitive adhesive sheet or the pressure-sensitive adhesive layer (hereinafter referred to as “first aspect”), the pressure-sensitive adhesive is a stem polymer made of an acrylic polymer and a branch polymer made of a polyether polyurethane (“first aspect”). An embodiment in which a graft polymer having a "graft chain") is contained as a main component resin can be mentioned.

The "main component resin" means a resin having the highest mass ratio among the resins constituting the present pressure-sensitive adhesive, and preferably occupies 50% by mass or more of the resin constituting the present pressure-sensitive adhesive. Among them, it is preferable to occupy 70% by mass or more, 80% by mass or more, and 90% by mass or more (including 100% by mass).

If a graft copolymer having a urethane component segment as a branch polymer is used as a main component resin, the Hansen solubility parameter (δp, δh, details described below) on the surface can be efficiently increased even if the amount of the polyurethane component is small. It is more preferable because it can be used.
The polyether type polyurethane is a polyurethane having a plurality of molecular chains having urethane bonds derived from the polyether polyol component, and the details will be described below.

The polyurethane of the branch polymer is preferably a (meth) acryloyl group-terminated polyurethane from the viewpoint of enhancing the compatibility with the acrylic polymer and the resilience after elongation.
That is, it is preferable that the graft polymer has (meth) acryloyl group-terminated polyurethane bonded as a branch component to the main chain made of an acrylic polymer.
This graft polymer has an acrylic component segment and a urethane component segment by itself.

The (meth) acryloyl group-terminated polyurethane is preferably a polyurethane in which a hydroxyl group-containing acrylate is added to the end of the polyurethane. Such polyurethane is available under the trade name UKW series of Taisei Fine Chemical Co., Ltd.

A graft polymer having an acrylic polymer as a trunk and polyurethane bonded as a branch component is a pressure-sensitive adhesive sheet having high δp and δh on the surface HSP because the polyurethane is exposed on the surface of the pressure-sensitive adhesive sheet.

The mass average molecular weight of the acrylic polymer as the main chain is preferably, for example, 50,000 to 1,300,000, and the mass average molecular weight of the polyurethane moiety of the branch component is, for example, 1,000 to 20,000. Is preferable.
Here, the mass average molecular weight is a value measured by gel permeation chromatography in terms of polystyrene.

In the first aspect, the pressure-sensitive adhesive is formed from a pressure-sensitive adhesive composition containing an initiator and / or a cross-linking agent, other resin components, and additives in addition to the polymers (a) to (c). You can also.
Among them, the pressure-sensitive adhesive composition is preferably a light or thermosetting pressure-sensitive adhesive composition, and in that case, it often contains an initiator and / or a cross-linking agent.

(Initiator)
The initiator is not particularly limited, and for example, those activated by heat and those activated by active energy rays can be used.
Further, those that generate radicals and cause radical reactions, and those that generate cations and anions and cause addition reactions can be used.

Specific examples thereof include organic peroxides and azo compounds.
Examples of the organic peroxide include lauroyl peroxide, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, t-hexylperoxypivalate, and t-butylperoxypivalate. , 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexane, t-hexylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, t -Butyl peroxyisobutyrate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate and the like can be mentioned.

Examples of the azo compound include azobisisobutyronitrile and azobiscyclohexanecarbonitrile. These initiators may be used alone or in combination of two or more.

In addition to the above, for example, a compound (so-called photoinitiator) that generates an active radical species by irradiating with light such as ultraviolet rays or visible light, more specifically, light having a wavelength of 200 nm to 780 nm is a preferable example. Can be mentioned.

As the photoinitiator, either a cleavage-type photoinitiator or a hydrogen-drawing-type initiator can be used, or both can be used in combination.

Examples of the cleavage-type photoinitiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexylphenylketone, and 2-hydroxy-2-methyl-1-phenyl-propane-1-. On, 1- (4- (2-hydroxyethoxy) phenyl) -2-hydroxy-2-methyl-1-propane-1-one, 2-hirodoxy-1- [4- {4- (2-hydroxy-2) -Methyl-propionyl) benzyl} phenyl] -2-methyl-propane-1-one, oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone), phenylglycoxylic Methyl acid, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butane-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1- On, 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone, bis (2,4,6-trimethylbenzoyl)- Phenylphosphinoxide, 2,4,6-trimethylbenzoyldiphenylphosphinoxide, (2,4,6-trimethylbenzoyl) ethoxyphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) 2,4,4-trimethylpentyl Phenyl oxide, or derivatives thereof, and the like can be mentioned.

When the cleavage-type photoinitiator is used, the photoinitiator changes its structure after the photoreaction is completed and is inactivated. Therefore, the photoinitiator does not remain as an active species after the curing reaction is completed, resulting in unexpected photodegradation and the like. It is preferable because there is no risk.

Examples of the hydrogen abstraction type photoinitiator include benzophenone, 4-methyl-benzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 4- (meth). Acryloyloxybenzophenone, Methyl 2-benzoylbenzoate, Methyl benzoylate, Bis (2-phenyl-2-oxoacetic acid) Oxybisethylene, 4- (1,3-Acryloyl-1,4,7,10,13-penta) Oxotridecyl) benzophenone, thioxanthone, 2-chlorothioxanthone, 3-methylthioxanthone, 2,4-dimethylthioxanthone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, or any of these. Derivatives and the like can be mentioned.

It is preferable to use the hydrogen abstraction type photoinitiator because the photoinitiator can also undergo a hydrogen abstraction reaction from various parts of the polymer, and thus a more complicated crosslinked structure can be formed.
Further, the hydrogen-extracting photoinitiator can function as an active species repeatedly by repeatedly irradiating with light even after being used for the photocuring reaction once.

In particular, in the present invention, when a photocuring reaction is carried out on a polymer in which polyurethane is bonded as a branch component to the main chain made of the acrylic polymer described above using a hydrogen-drawing type photoinitiator, a highly polar member sheet is subjected to. It can be a pressure-sensitive adhesive sheet or a pressure-sensitive adhesive layer having high bending resistance.

A thermal polymerization initiator can be used in addition to the photopolymerization initiator for forming the crosslinked structure.

Examples of the thermal polymerization initiator include azo compounds, quinine, nitro compounds, acyl halides, hydrazones, mercapto compounds, pyrylium compounds, imidazoles, chlorotriazines, benzoins, benzoin alkyl ethers, diketones, phenones, and dilauroyl peroxides and NOF Co. .. Can be mentioned from organic peroxides such as 1,1-di (t-hexylperoxy) -3,3,5-trimethylcyclohexane available as PERHEXA TMH.

(Crosslinking agent)
Crosslinking agents can be used to form the crosslinked structure.
Any high molecular weight component containing an active hydrogen group such as a hydroxyl group can be crosslinked with isocyanate, carbodiimide, or the like.

As the cross-linking agent, an isocyanate compound is preferable, and the isocyanate compound described in the following section on polyurethane can be preferably used.
Further, it is also preferable in the process of forming the pressure-sensitive adhesive sheet or the pressure-sensitive adhesive layer to further add a transition metal catalyst or the like in order to promote the cross-linking reaction.

The initiator is often used at a concentration of 0.01 to 10% by weight, or 0.01 to 5% by weight, based on the total mass of the pressure-sensitive adhesive. A mixture of initiators may be used.

(Other resin components)
In the first aspect, the pressure-sensitive adhesive may contain other resin components such as polyester, polyamide, polyolefin, and olefin-based monomers, if necessary, in addition to the above.

(Other additives)
In the first aspect, in addition to the above, the present pressure-sensitive adhesive may be used as other additives, for example, a tackifier, a curing accelerator, a filler, a coupling agent, an ultraviolet absorber, and an ultraviolet stabilizer. It may contain one or more of agents, antioxidants, stabilizers, pigments, rust preventives and the like.
The amount of these additives is typically selected so as not to adversely affect the curing of the pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer, or the physical properties of the pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer.

The tackifier may generally be any compound or mixture of compounds that enhances the tackiness of the pressure-sensitive adhesive composition.
The tackifier is not particularly limited, and conventionally known ones can be used. For example, terpene-based tackifiers, phenol-based tackifiers, rosin-based tackifiers, aliphatic petroleum resins, aromatic petroleum resins, copolymerized petroleum resins, alicyclic petroleum resins, xylene resins, epoxy-based Examples thereof include a tackifier, a polyamide-based tackifier, a ketone-based tackifier, an elastomer-based tackifier, and the like, and these can be used alone or in combination of two or more.

<Second aspect>
As another preferable aspect of the pressure-sensitive adhesive sheet or the pressure-sensitive adhesive layer (hereinafter referred to as "second aspect"), the pressure-sensitive adhesive contains any one or more of the following (d) and (e). Aspects formed from the composition can be mentioned.

(D) Acrylic polymer and polyether type polyurethane (e) A mixture of monomer components constituting the acrylic polymer or a partial polymer thereof and a polyether type polyurethane

In the above (d), in the present pressure-sensitive adhesive, the acrylic component segment is formed by the acrylic polymer, and the urethane component segment is formed by the polyether type polyurethane.

In (e), in the present pressure-sensitive adhesive, an acrylic component segment is formed by a mixture of monomer components constituting an acrylic polymer or a partial polymer thereof, and a urethane component segment is formed by a polyether polyurethane.

The pressure-sensitive adhesive composition containing either (d) or (e) is an initiator and / or a cross-linking agent and other resin components other than the above (d) or (e) as in the first aspect. , Additives can be included.
The pressure-sensitive adhesive composition is preferably a light or thermosetting pressure-sensitive adhesive composition that cures with light or heat, in which case it often contains an initiator and / or a cross-linking agent.
Since the preferred embodiments of the initiator, the cross-linking agent, other resin components and the additive are the same as described above, they are omitted.

(Acrylic polymer)
In the first aspect and the second aspect, the acrylic polymer may be a polymer or a copolymer containing a (meth) acrylic acid alkyl ester as a monomer.

As the (meth) acrylic acid ester, for example, since the G'(-20 ° C.) of the present adhesive sheet or the present adhesive layer is 300 kPa or less, the monomer having a low Tg of −45 to −30 ° C. is used. Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-hexyl (meth) acrylate, (Meta) acrylic acid alkyl esters such as n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, isomiristyl (meth) acrylate, stearyl (meth) acrylate, and 4-hydroxybutyl (meth). (Meta) acrylic acid esters having hydroxyl groups such as acrylates and 2-hydroxyethyl (meth) acrylates, cyclohexyl (meth) acrylates, isobornyl (meth) acrylates, benzyl (meth) acrylates, 2-butoxyethyl (meth) acrylates, Examples thereof include 2-phenoxyethyl (meth) acrylate, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, polypropylene glycol mono (meth) acrylate, and 2-isocyanatoethyl (meth) acrylate. These (meth) acrylic acid esters may be used alone or in combination of two or more.

Further, as the monomer component constituting the acrylic polymer, various vinyl compounds and the like may be used in addition to the (meth) acrylic acid alkyl ester.

The vinyl compound is not particularly limited, and is, for example, a (meth) acrylamide compound such as N, N-dimethylacrylamide, N, N-diethylacrylamide, N-isopropylacrylamide, N-hydroxyethylacrylamide, acrylamide, N-vinylpyrrolidone, N. -Vinylcaprolactam, N-vinylacetamide, N-acrylamide, acrylonitrile, styrene, vinyl acetate and the like can be mentioned. These vinyl compounds may be used alone or in combination of two or more.

The hydroxyl value (mgKOH / g resin) of the acrylic polymer is preferably 5 to 200, and more preferably 20 or more or 180 or less.
The hydroxyl value of the acrylic polymer can be controlled by the polymerization composition ratio of the hydroxyl group-containing monomer component from the (meth) acrylic acid ester.
When the hydroxyl value is in the above range, it is possible to introduce a urethane component segment utilizing the reaction with the hydroxyl group.

The preferable lower limit of the mass average molecular weight (Mw) of the acrylic polymer is 400,000, and the preferable upper limit is 1.3 million.
When the mass average molecular weight (Mw) of the acrylic polymer is 400,000 or more, the stickiness of the pressure-sensitive adhesive sheet or the pressure-sensitive adhesive layer does not become too high, punching processability can be maintained, and both adhesive strength and resilience can be achieved. Will be.
On the other hand, when the mass average molecular weight (Mw) of the acrylic polymer is 1.3 million or less, it is possible to form an adhesive sheet or an adhesive layer having a smooth surface and a small haze.

To obtain the acrylic polymer, the monomer component may be radically reacted in the presence of an initiator.
Examples of the method of radically reacting the monomer components, that is, the polymerization method include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, bulk polymerization and the like. Of these, solution polymerization is preferable because the molecular weight distribution (Mw / Mn) can be controlled by adjusting the initiator, polymerization temperature, and the like.

When solution polymerization is used as the polymerization method, examples of the reaction solvent include ethyl acetate, toluene, methyl ethyl ketone, methyl sulfoxide, ethanol, acetone, diethyl ether and the like. These reaction solvents may be used alone or in combination of two or more.
When solution polymerization is used as the polymerization method, the polymerization temperature is preferably about 40 to 90 ° C.

(Polyester type polyurethane)
In the second aspect, the polyether polyurethane is a polyurethane having a plurality of molecular chains having a urethane bond obtained by reacting a polyether polyol with a polyfunctional isocyanate compound.
In the present invention, the polyether polyurethane preferably has two or more urethane bonds in the molecule.

Examples of the polyol that is usually a raw material for polyurethane include polyether polyols, polyester polyols, polycarbonate-based polyols, polyolefin polyols, acrylic polyols, and the like. In the present invention, it is particularly preferable to have the polyether polyols from the viewpoint of compatibility with the acrylic polymer.

The polyfunctional isocyanate compound is preferably diisocyanate.
Further, from the viewpoint of prevention of gelation and compatibility with the acrylic polymer, 4,4'-methylenebis (phenylisocyanate) (MDI); toluene diisocyanate (TDI); m-xylene diisocyanate (XDI); hexamethylene is particularly preferable. Diisocyanide (HDI); Methylenebis (4-cyclohexyldiisocyanate) (HDMI®); Naphthalene-1,5-diisocyanide (NDI); 3,3'-dimethyl-4,4'-biphenyldiisocyanate (TODI); 1 , 4-Di-Isocyanatobenzene (PPDI); phenyl-1,4-4-diisocyanate; trimethylhexamethyldiisocyanate (TDMI); isophorone diisocyanate (IPDI); 1,4-cyclohexyldiisocyanide (CHDI); diphenylether 4, From 4'-diisocyanides; p, p'-diphenyldiisocyanides; lysine diisocyanates (LDI); 1,3-bis (isocyanatomethyl) cyclohexane; polymethylpolyphenylisocyanides (PMDI); and isomers and / or mixtures thereof. It is selected from the group of.

The mass ratio of the polyether polyol, which is a component derived from the polyether polyol, to the polyfunctional isocyanate compound, which is a component derived from isocyanate, is the mass ratio (% by mass) of the polyether polyol from the viewpoint of compatibility with the acrylic polymer. Is preferably larger than the mass ratio (% by mass) of the polyfunctional isocyanate compound. In particular, the mass ratio (mass%) of the polyether glycols, which is a component derived from polyether glycol, is larger than the mass ratio (mass%) of the polyfunctional isocyanate compound, which is a component derived from isocyanate. Since the influence of the intermolecular hydrogen bond of the urethane component can be reduced while improving the solubility, it is also preferable from the viewpoint of enhancing the restorability after elongation.
Therefore, it is preferable that the mass ratio (mass%) of the component derived from polyether glycol is larger than the mass ratio (mass%) of the component derived from isocyanate.

In the second aspect, the pressure-sensitive adhesive is preferably formed by curing a pressure-sensitive adhesive composition containing at least one of the above (d) and (e). In particular, the pressure-sensitive adhesive composition is preferably cured by light or heat.
By curing the pressure-sensitive adhesive composition, the adhesive strength and cohesive power of the pressure-sensitive adhesive sheet or the pressure-sensitive adhesive layer can be enhanced.

From the above viewpoint, it is preferable that the polyether polyurethane has one or more acryloyl groups or methacryloyl groups in one molecule. By photocuring and using the pressure-sensitive adhesive composition having an acryloyl group or a methacryloyl group, the adhesive force and the cohesive force of the present pressure-sensitive adhesive sheet or the present pressure-sensitive adhesive layer can be enhanced.

Further, in the second aspect, by using a pressure-sensitive adhesive composition containing a polyether-type polyurethane having one or more acryloyl groups or methacryloyl groups in the one molecule and a hydrogen-drawing type photoinitiator. A crosslinked polymer that forms a crosslinked structure between the acrylic component segment and the urethane component segment is generated, and the adhesive force and the cohesive force of the present adhesive sheet or the present adhesive layer can be enhanced.

As a polyether type polyurethane having one or more acryloyl group or methacryloyl group (hereinafter collectively referred to as (meth) acryloyl group) in one molecule, for example, a (meth) acryloyl group is provided at one end or both ends. Examples thereof include a polyether type polyurethane having.
In addition, it may be a polyether type polyurethane having a hydroxyl group and a (meth) acryloyl group in one molecule, or a polyether type polyurethane having an isocyanate group and a (meth) acryloyl group in one molecule. There may be.

From the same viewpoint, it is preferable that the polyether polyurethane has one or more hydroxyl groups in one molecule. By thermally curing and using a pressure-sensitive adhesive composition containing a polyether polyurethane having a hydroxyl group and a cross-linking agent such as isocyanate, a cross-linked polymer forming a cross-linked structure between an acrylic component segment and a urethane component segment is produced. Therefore, the adhesive strength and cohesive strength of the present adhesive sheet or the present adhesive layer can be enhanced.
Examples of the polyether type polyurethane having one or more hydroxyl groups in one molecule include a polyether type polyurethane having hydroxyl groups at one end or both ends.

<Storage modulus>
The adhesive sheet and the adhesive layer preferably have a storage elastic modulus (G'(-20 ° C)) of -20 ° C obtained by dynamic viscoelastic measurement in a shear mode with a frequency of 1 Hz of 300 kPa or less, preferably 200 kPa or less. Is more preferable.
By setting G'(-20 ° C.) in the above range, it is possible to prevent the member sheet from cracking when the member sheet described later is attached to the present adhesive sheet or the present adhesive layer and the bending operation is performed.
The adhesive sheet and the present adhesive layer used in the bendable image display device need to be softened at the folding speed (frequency), and in order to be flexible at high frequencies, the temperature of dynamic viscoelasticity- Since it is required that G'is low in the low temperature range, that is, the glass transition temperature Tg of the pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer is low by time conversion measurement, the storage elastic modulus at -20 ° C (G'(-20 ° C)). Is required to be 300 kPa or less.

In order to achieve the above G'(-20 ° C), the maximum value of the loss tangent (tan δ) obtained by dynamic viscoelasticity measurement in the shear mode with a frequency of 1 Hz is -20 ° C in the adhesive sheet and the adhesive layer. The following is preferable.
In order to adjust the storage elastic modulus (G'(-20 ° C.)) of -20 ° C in the pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer to the above range, an adhesive having a urethane component segment and an acrylic component segment is used as described above. The range may be adjusted, and it is particularly preferable to use the pressure-sensitive adhesive shown in the first aspect or the second aspect. However, the method is not limited to that method.

The adhesive sheet and the adhesive layer preferably have a storage shear elastic modulus (G'(60 ° C.)) of 60 ° C. obtained by dynamic viscoelasticity measurement in a shear mode at a frequency of 1 Hz of 10 kPa or more, preferably 20 kPa or more. Is more preferable.
By setting the storage shear modulus (G'(60 ° C.)) in the above range, for example, when the present adhesive sheet or the present adhesive layer is attached to a member sheet to form a laminated sheet, the laminated sheet is formed at room temperature to high temperature. It is possible to reduce the interlayer stress at the time of bending, and it is possible to suppress delamination and cracking of the member sheet.

In order to adjust the storage elastic modulus (G'(-20 ° C.)) of -20 ° C in the pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer to the above range, an adhesive having a urethane component segment and an acrylic component segment is used as described above. The range may be adjusted, and it is particularly preferable to use the pressure-sensitive adhesive shown in the first aspect or the second aspect.

<Loss tangent (tanδ)>
In the present adhesive sheet and the present adhesive layer, it is preferable that the maximum value of the loss tangent (tan δ) obtained by dynamic viscoelasticity measurement in a shear mode with a frequency of 1 Hz is −20 ° C. or lower.
This maximum value is more preferably −30 ° C. or lower, and even more preferably −40 ° C. or lower. The lower limit is not specified, but it is usually -70 ° C or higher.
This maximum temperature is a guideline for the glass transition temperature (Tg) of the adhesive sheet, and when this value is -20 ° C or lower, the storage elastic modulus at low temperature is sufficiently lowered, and stress due to bending operation is obtained. Can be reduced.
It is particularly preferable that the pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer have a peak of a maximum value of 0.1 or more for the loss tangent (tan δ) in shearing at a frequency of 1 Hz in the temperature range of −60 to −20 ° C.

In the present invention, the elastic modulus (storage elastic modulus) G'and the viscous modulus (loss elastic modulus) G'and the loss tangent (tan δ = G'/ G') at various temperatures can be measured using a strain leometer. can.

In order to adjust the maximum value of the loss tangent (tan δ) in the above range in the present adhesive sheet and the present adhesive layer, it may be adjusted in the above range by using an adhesive having a urethane component segment and an acrylic component segment. , It is preferable to use the pressure-sensitive adhesive shown in the first aspect or the second aspect. However, the method is not limited to these methods.

<Restoring force>
The adhesive sheet and the adhesive layer are stretched to a length four times the initial length by pulling both ends of the adhesive sheet or the adhesive layer in opposite directions, held in that state for 10 minutes, and then one end is released. The length after 20 minutes is preferably 1.0 to 1.6 times the initial length.
The above operation is related to the recoverability of the adhesive sheet or the laminate in which the adhesive layer is bonded to the member sheet, the flexible image display device member, and the image display device when unfolded after bending, and is within the above range. By the above, the creases of the laminated body, the present flexible image display device member, and the image display device can be made inconspicuous.

In the present adhesive sheet and the present adhesive layer, in order to adjust the restoring force within the above range, an adhesive having a urethane component segment and an acrylic component segment may be used to adjust the restoring force within the above range, and in particular, the first aspect described above. Alternatively, it is preferable to use the pressure-sensitive adhesive shown in the second aspect. However, the method is not limited to these methods.

<Haze>
The pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer preferably have a haze of less than 1.0%, more preferably less than 0.7%.
When the haze of the adhesive sheet and the adhesive layer is within the above range, it can be suitably used as an adhesive sheet and an adhesive layer for an image display device.
Here, the haze is measured according to JIS K7136.
When the adhesive sheet or the present adhesive layer is a laminated body bonded to the member sheet, the haze of the adhesive sheet and the present adhesive layer can be considered to be less than or equal to that value by measuring the haze of the laminated body. can.

In the present adhesive sheet and the present adhesive layer, in order to adjust the haze to the above range, an adhesive having a urethane component segment and an acrylic component segment may be used to adjust the haze to the above range. It is preferable to use the pressure-sensitive adhesive shown in the second aspect. However, the method is not limited to these methods.

<Total light transmittance>
The pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer preferably have a total light transmittance of 85% or more, more preferably 88% or more, and even more preferably 91% or more when the thickness is 100 μm.
Here, the total light transmittance is measured according to JIS K7361-1.

In the present adhesive sheet and the present adhesive layer, in order to adjust the total light transmittance to the above range, an adhesive having a urethane component segment and an acrylic component segment may be used to adjust the total light transmittance to the above range. It is preferable to use the pressure-sensitive adhesive shown in the above aspect or the second aspect. However, the method is not limited to these methods.

<Hansen solubility parameter>
In the adhesive sheet and the adhesive layer, the polar term δp is 2.0 MPa ^0.5 or more and the hydrogen bond term δh is 5 in the Hansen solubility parameter (δd, δp, δh) on the surface of the adhesive sheet or the adhesive layer. It is preferably 0.0 MPa ^0.5 or more.
By containing the urethane component segment in the pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer, it is possible to increase δp in the surface HSP as compared with the pressure-sensitive adhesive sheet or the pressure-sensitive adhesive layer composed of only the acrylic component segment.
Therefore, the wettability with various display films (member sheets) having a large δp is improved, the interfacial adhesive strength is improved, and as a result, it is possible to contribute to the improvement of the adhesive strength in the peeling test.

Here, the Hansen solubility parameter (HSP) is an index showing the solubility of a substance in another substance. The HSP is a three-dimensional space in which the solubility parameter introduced by Hildebrand is divided into three components, a dispersion term δd, a polarity term δp, and a hydrogen bond term δh.

The dispersion term δd is a value indicating the effect due to the London dispersion force, the polar term δp is a value indicating the effect due to the dipole interpole force, and the hydrogen bond term δh is a value indicating the effect due to the hydrogen bond force.
δd: Energy derived from the London dispersion force between molecules δp: Energy derived from the polar force between molecules δh: Energy derived from the hydrogen bonding force between molecules. (Here, each unit is MPa ^0.5 .)

The definition and calculation of HSP is described in the following literature.
Charles M. Hansen, Hansen Solubility Parameters: A Users Handbook (CRC Press, 2007).

The dispersion term reflects the London dispersion force, the polarity term reflects the dipole moment, and the hydrogen bond term reflects the action of water, alcohol, and the like. Then, it can be determined that the vectors having similar vectors by HSP have high solubility, and the similarity of the vectors can be determined by the distance of the Hansen solubility parameter (HSP distance). Alternatively, the solubility parameter of Nsen can be an index not only for determining the solubility but also for determining how easily one substance is present in another substance, that is, how good the dispersibility is.

In the present invention, the surface HSP [δd, δp, δh] is the Young-Dupre formula from the value of the contact angle 30 seconds after contacting 2 μL of droplets of various solvents known for HSP with the surface of the pressure-sensitive adhesive sheet or the pressure-sensitive adhesive layer. In addition, γ _SL was calculated from the equations of Hata / Kitazaki and Extended Hawks, and from the relationship between the Hansen solubility parameter and surface tension (Equation 1) (Hansen Solubility Parameters 50th anniversary conference, preprint 2017 ^PP.14-21 (2017)). , Ra and (γ _SL / (V _L ^1/3 )) ^1/2 are determined to be the most correlated.
(Equation 1) δd ² + δp ² + 0.068 δh ² = 13.9γ _SL (1 / (V _L ^1/3 ))

In the Hansen solubility parameter (δd, δp, δh) of the pressure-sensitive adhesive sheet or the surface of the pressure-sensitive adhesive layer, the polar term δp is preferably 2.0 MPa ^0.5 or more, and 3.0 MPa ⁰ . It is more preferably ^.5 or more.
The hydrogen bond term δh is preferably 5.0 MPa ^0.5 or more, and more preferably 6.0 MPa ^0.5 or more.
When the δp and δh of the adhesive sheet and the adhesive layer are in the above range, the wettability to high-polarity (optical) member sheets such as polyamide, polyimide, epoxy, polyester, and TAC film is improved, and the interfacial adhesive strength is increased. It is possible to increase the adhesive strength and improve the adhesive strength as compared with the conventional acrylic adhesive sheet.

As described above, since the pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer contain a urethane component segment having a high component of δp, δh, δp, δh at the surface HSP is higher than that of a pressure-sensitive adhesive sheet consisting of only an acrylic component segment. Can be increased.
Further, in order to increase δp and δh in the HSP of the surface, the blending amount is adjusted so that the urethane component segment is exposed on the surface of the pressure-sensitive adhesive sheet, or it is shown in the first or second aspect. It is preferable to use a pressure-sensitive adhesive to form the main pressure-sensitive adhesive sheet and the main pressure-sensitive adhesive layer.

<Gel fraction>
The gel fraction of the present adhesive sheet and the present adhesive layer is preferably 55% or more, more preferably 60% or more, and even more preferably 65% or more.
When the gel fraction of the present adhesive sheet and the present adhesive layer is 55% or more, the shape can be sufficiently maintained.

In order to adjust the gel content in the pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer within the above range, in the manufacturing process of the pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer, for example, when the pressure-sensitive adhesive composition is cured by light or heat as described later. , The degree of cross-linking may be adjusted. For example, in the case of photocrosslinking a polyether type polyurethane and an acrylic polymer, the degree of crosslinking can be adjusted by adjusting the irradiation amount of light or the like, and the gel fraction can be adjusted. However, the method is not limited to this method.

<Thickness>
The thickness of the adhesive sheet and the adhesive layer is not particularly limited. It is preferably 0.005 mm or more, more preferably 0.010 mm or more, still more preferably 0.150 mm or more.
On the other hand, the upper limit is preferably 1.000 mm or less, more preferably 0.700 mm or less, still more preferably 0.500 mm or less.
When the thickness is 0.005 mm or more, the handleability is good, and when the thickness is 1.000 mm or less, it can contribute to the thinning of the laminated body to which the member sheets are bonded.

<Preferable use of this adhesive sheet>
The present adhesive sheet is preferably used for bonding members constituting the display member (also referred to as "display member"), in particular, a flexible member for a display used for producing a display, and for producing a flexible display. It is particularly preferable to use it as an adhesive component for a flexible display used in the above.
As the flexible member, the same flexible member as those described later can be used.

<Components of this flexible image display device member>
Next, among the constituent elements of the flexible image display device member, elements other than the adhesive layer will be described.

<Flexible member>
Examples of the flexible member constituting the flexible image display device include a flexible display such as an organic electroluminescence (EL) display, a cover lens (cover film), a polarizing plate, a splitter, a retardation film, a barrier film, and a viewing angle compensation. Examples thereof include flexible members for displays such as films, brightness improving films, contrast improving films, diffusion films, transflective reflective films, electrode films, transparent conductive films, metal mesh films, and touch sensor films. Any one of these or two of the two may be used in combination. For example, a combination of a flexible display and other flexible members, or a combination of a cover lens and other flexible members can be mentioned.

The flexible member means a member that can be bent, in particular, a member that can be repeatedly bent. In particular, a member capable of fixing to a curved shape having a bending radius of 25 mm or more, particularly a member capable of withstanding repeated bending actions with a bending radius of less than 25 mm, more preferably a bending radius of less than 3 mm is preferable.

<HSP of flexible member>
Further, for the reason described below, the HSP on the surface of at least one of the above two flexible members preferably has a δp of 10.0 MPa ^0.5 or more and 20.0 MPa ^0.5 or less. Polyamide, polyimide, polyester, epoxy resin, etc. are usually in this range, but by adjusting to the above range by corona treatment, plasma treatment, primer treatment, etc., the interfacial adhesive strength with the adhesive layer can be enhanced. Can be done.

<HSP distance (Ra)>
Further, for the same reason as described below, in the flexible image display device member, the HSP distance (Ra) between the Hansen solubility parameter on the surface of the flexible member and the Hansen solubility parameter on the surface of the adhesive layer is 17.0 or less. It is preferably 16.0 or less, more preferably 15.0 or less, and even more preferably 15.0 or less.
Further, the method of calculating the HSP distance (Ra) is also as described below.

For the reasons described below, for example, the 180 degree peel strength (JIS Z 0237) of the adhesive layer for the flexible member, particularly the flexible member made of a highly polar film, at a peel rate of 300 mm / min at 60 ° C. is 8N / 25 mm. The above can be achieved, and more preferably 10 N / 25 mm or more.
When the adhesive force between the flexible member and the present adhesive layer is within the above range, the reliability of the image display device can be improved without the flexible member being peeled off due to stress at the time of bending.

The flexible member means a member that can be bent, in particular, a member that can be repeatedly bent, and in particular, a member having a bending radius of 25 mm or more and capable of a curved fixed shape, particularly a bending radius of less than 25 mm. Preferably, it refers to a member capable of withstanding repeated bending actions with a bending radius of less than 3 mm.

<< Adhesive parts >>
The adhesive component according to an example of the embodiment of the present invention (hereinafter referred to as “the present component”) includes the adhesive having the urethane component segment and the acrylic component segment described above (the present adhesive described above), and is wearable, for example. It can be suitably used for flexible devices such as electronic devices and foldable displays.

This component preferably has one or more of the above-mentioned predetermined properties (storage elastic modulus, loss tangent (Tanδ), restoring force, haze, total light transmittance, Hansen solubility parameter and gel fraction). ..
Above all, in the Hansen solubility parameter (δd, δp, δh) on the surface of this component, the polar term δp is 2.0 MPa ^0.5 or more and the hydrogen bond term δh is 5.0 MPa ^0.5 or more. It is preferable to have it.

With the advent of bendable image display devices, member sheets used for them are also being used that are compatible with bending. For example, as a front cover film, a transparent polyimide film that is resistant to tensile stress due to bending, is difficult to whiten, has high high temperature reliability, and has excellent scratch resistance has been adopted.
Such a transparent polyimide film contains a large amount of an aromatic skeleton and an imide group and / or an amide group in order to achieve both high temperature reliability and transparency, and depending on the type, contains a fluorine-based functional group. Sometimes there is.
Therefore, it is an extremely polar film, and the adhesive parts used in conventional displays cannot adhere firmly when applied to flexible devices, and can be peeled off due to bending stress or displayed. There is a problem that the user may mistakenly think that it is a part of the protective film and peel it off.

Further, the polarizing plate assembly is becoming thinner and thinner, and a thin member sheet having a highly polar outermost surface is obtained by laminating a coating type liquid crystal layer or a TAC film (cellulose triacetate film) on the outermost surface. With the advent, it has been difficult for such member sheets to adhere firmly with conventional adhesive parts.

On the other hand, when the Hansen solubility parameters (δp and δh) on the surface of this component are within the above range, wetting of highly polar (optical) member sheets such as polyamide, polyimide, epoxy, polyester, and TAC film is possible. It improves, the interfacial adhesive strength is increased, and the adhesive strength can be improved as compared with the conventional acrylic adhesive parts.

<< This laminated body >>
The laminate according to an example of the embodiment of the present invention (hereinafter, may be referred to as “the present laminate”) is the above-mentioned adhesive sheet or the laminate having a member sheet on at least one surface of the present adhesive layer.

The laminated body may be referred to as a member sheet (hereinafter sometimes referred to as "first member sheet"), the present adhesive sheet or the present adhesive layer, and an arbitrary member sheet (hereinafter referred to as "second member sheet"). (A) and may be a laminated sheet having a structure in which they are laminated in this order.
At this time, the first member sheet and the second member sheet may be the same or different.

<Material sheet>
Examples of the main component of the adhesive sheet or the member sheet to be the adherend of the adhesive layer include polycycloolefin, triacetylcellulose, polymethylmethacrylate, polyester, epoxy resin, polyimide, polyamide and the like. It may be one kind of resin or two or more kinds of resins.
Here, the "main component" means a component that occupies the largest mass ratio, and specifically, occupies 50% by mass or more of a member sheet or a composition forming the member sheet. It is more preferable to occupy 55% by mass or more, particularly 60% by mass or more (including 100% by mass).

Further, the member sheet may be ultra-thin glass (UTG). Here, the ultra-thin film refers to chemically strengthened glass having a thickness of 70 μm or less.

Among them, the member sheet containing one or more kinds of resins selected from the group consisting of polyamide, polyimide, epoxy resin, triacetyl cellulose and polyester as a main component is particularly highly polar, but this adhesive sheet has δp. Since δh is high, a particular effect can be found.

Among them, a polyimide film containing polyimide as a main component is suitably used as a member sheet for a flexible display because it has a high Tg, a low coefficient of linear expansion, excellent high-temperature reliability, high tensile strength, and is unlikely to cause whitening due to bending. To. Although ordinary polyimide is often brown, a transparent polyimide film in which the chemical structures of the diamine component and the dicarboxylic acid component are appropriately selected and the band gap is adjusted is particularly preferable.

<Thickness>
The thickness of the laminated body is not particularly limited. For example, as an example when used in an image display device, the present laminate is in the form of a sheet, and if the thickness is 0.01 mm or more, the handleability is good, and if the thickness is 1.0 mm or less. If there is, it can contribute to the thinning of the laminated body.
Therefore, the thickness of the present laminate is preferably 0.01 mm or more, and more preferably 0.03 mm or more, particularly 0.05 mm or more. On the other hand, the upper limit is preferably 1.0 mm or less, and more preferably 0.7 mm or less, particularly 0.5 mm or less.

<HSP of member sheet>
In this laminated body, the HSP on the surface of the member sheet preferably has δp of 10.0 MPa ^0.5 or more and 20.0 MPa ^0.5 or less. Polyamide, polyimide, polyester, epoxy resin, etc. are usually in this range, but by adjusting to the above range by corona treatment, plasma treatment, primer treatment, etc., the interfacial adhesive strength with the adhesive sheet can be enhanced. Can be done.

<HSP distance (Ra)>
The adhesive force between the member sheet and the adhesive sheet or the present adhesive layer is determined by the viscoelastic element such as the magnitude of the loss elastic modulus (G ") at the peeling frequency (speed) and the interfacial adhesive force element such as wetting. Is normal.
However, there is a high possibility that a low Tg adhesive sheet or adhesive layer for bending cannot be expected to be significantly improved due to restrictions on viscoelasticity, and the surface HSP of the adhesive sheet or adhesive layer is controlled to improve the interfacial adhesive strength. It has been found that the adhesive strength can be effectively increased.

Therefore, in the present laminated body, the HSP distance (Ra) between the Hansen solubility parameter on the surface of the member sheet and the Hansen solubility parameter on the surface of the adhesive sheet or the adhesive layer is preferably 17 or less, preferably 16 or less. It is more preferable, and it is further preferable that it is 15 or less.

Here, the HSP distance (Ra) is calculated by (Equation 2).
(Equation 2) HSP distance (Ra) = {4 × (δd _A − δd _S ) ² + (δp _A − δp _S ) ² + (δh _A − δh _S ) ² } ^0.5
In Equation 2, δd _A , δp _A , and δh _A indicate δd, δp, and δh of the present adhesive sheet, respectively, and δd _S , δp _S , and δh _S indicate δd, δp, and δh of the present member sheet, respectively. show.

By setting the HSP distance (Ra) in the above range, the adhesive strength between the member sheet and the present adhesive sheet or the present adhesive layer can be sufficiently increased.
There are various methods for evaluating the adhesive strength. For example, the adhesive strength of this adhesive sheet for a member sheet, particularly a member sheet made of a highly polar film, at a peeling speed of 300 mm / min at 60 ° C. (JIS Z 0237). Can be 8N / 25mm or more, and more preferably 10N / 25mm or more.
When the adhesive force between the member sheet and the present adhesive sheet or the present adhesive layer is within the above range, the reliability of the image display device can be improved without the member sheet peeling off due to stress at the time of bending.

In order to make the HSP distance within the above range, for example, the urethane component of the adhesive sheet or the adhesive layer may be increased to increase δp and δh, or the HSP on the member sheet side may be close to the HSP of the adhesive sheet or the adhesive layer. It may be possible to apply a primer having the above. However, the method is not limited to these methods.

<Haze of laminated body>
The laminate preferably has a haze of less than 1.0%, more preferably less than 0.7%.
When the haze of this laminated body is within the above range, it can be suitably used as a constituent member for an image display device.
Here, the haze is measured according to JIS K7136.

<< Manufacturing method of this adhesive sheet and this adhesive layer >>
As an example of the method for producing the present adhesive sheet, an adhesive containing "polyether type polyurethane forming the urethane component segment in the present adhesive sheet" and "acrylic polymer forming the acrylic component segment in the present adhesive sheet". Examples thereof include a method of producing the present adhesive sheet by molding the composition into a sheet, curing the composition with light or heat, and appropriately processing the composition as necessary. However, the method is not limited to this method.

As another example of the method for producing the present pressure-sensitive adhesive sheet, a composition containing a graft polymer having a stem polymer made of an acrylic polymer and a branch polymer made of polyether-type polyurethane (also referred to as “graft chain”) as a main component resin. A method of producing the present pressure-sensitive adhesive sheet can be mentioned by molding the pressure-sensitive adhesive composition into a sheet shape, curing the pressure-sensitive adhesive composition with light or heat, and appropriately processing the pressure-sensitive adhesive composition as necessary. However, the method is not limited to this method.

As an example of the method for producing the present pressure-sensitive adhesive layer, the pressure-sensitive adhesive composition is prepared in the same manner as described above, and then the pressure-sensitive adhesive composition is coated on a member sheet or a flexible member, and the resin composition is cured by light or heat. Therefore, the present adhesive layer can be formed. However, the method is not limited to this method.

By further reacting the pressure-sensitive adhesive composition with light or heat, a structure in which the acrylic component segment and the urethane component segment are bonded is obtained as a result, so that the viscoelasticity of the pressure-sensitive adhesive sheet or the present pressure-sensitive adhesive layer is within the above range. It is considered that the present adhesive sheet adjusted to the above can be obtained.

However, these manufacturing methods are examples of methods for manufacturing the pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer are not limited to those manufactured by such a manufacturing method.

<Mixing and kneading of raw materials>
When preparing the pressure-sensitive adhesive composition, the above raw materials are kneaded using a temperature-adjustable kneader (for example, a dispenser, a single-screw extruder, a twin-screw extruder, a planetary mixer, a twin-screw mixer, a pressure kneader, etc.). Just do it.
When mixing various raw materials, various additives such as silane coupling agent and antioxidant may be blended with the resin in advance and then supplied to the kneader, or all the materials are melt-mixed in advance. It may be supplied after that, or a master batch in which only the additive is concentrated in a resin in advance may be prepared and supplied.

<Molding>
As a method for forming the pressure-sensitive adhesive composition into a sheet, known methods such as wet lamination, dry lamination, extrusion casting method using T-die, extrusion laminating method, calendar method, inflation method, injection molding, and liquid injection curing method. Etc. can be adopted. Above all, when producing a sheet, the wet lamination method, the extrusion casting method, and the extrusion laminating method are preferable.

<Curing>
In order to cure the pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer, the pressure-sensitive adhesive composition may be applied to a member sheet such as a release sheet and polymerized, or after the pressure-sensitive adhesive composition is polymerized and cured. It may be attached to a member sheet or the like.

When the pressure-sensitive adhesive composition contains an initiator, a cured product can be produced by irradiating with heat and / or active energy rays to cure the composition. In particular, the present pressure-sensitive adhesive sheet and the present pressure-sensitive adhesive layer can be produced by irradiating a molded body of the pressure-sensitive adhesive composition with heat and / or active energy rays.

Here, examples of the active energy rays to be irradiated include ionizing radiation such as α-rays, β-rays, γ-rays, neutron rays, and electron beams, ultraviolet rays, visible rays, etc. Ultraviolet rays are preferable from the viewpoint of reaction control.
Further, the irradiation energy of the active energy ray, the irradiation time, the irradiation method, and the like are not particularly limited.

<Another method>
As another embodiment of the method for producing the present pressure-sensitive adhesive sheet and the present pressure-sensitive adhesive layer, the pressure-sensitive adhesive composition may be dissolved in an appropriate solvent and carried out by using various coating methods.
When the coating method is used, the present pressure-sensitive adhesive sheet can be obtained by heat-curing in addition to the above-mentioned active energy ray irradiation curing.

In the case of coating, the thickness of the adhesive sheet can be adjusted by the coating thickness and the solid content concentration of the coating liquid.

<Surface treatment>
From the viewpoint of preventing blocking and foreign matter adhesion, it is preferable to laminate a protective film on at least one surface of the adhesive sheet or the adhesive layer.
Further, if necessary, at least one surface of the adhesive sheet or the adhesive layer may be embossed or various irregularities (cone, pyramid shape, hemispherical shape, etc.) may be processed.
Further, for the purpose of improving the adhesiveness to various adherend members, various surface treatments such as corona treatment, plasma treatment and primer treatment may be performed on the surface of the pressure-sensitive adhesive sheet.

In particular, the present adhesive sheet or the present adhesive layer may be a laminated body in which a release film is laminated on at least one side thereof.
Here, as the release film, it is preferable to use a release-treated polyethylene terephthalate (PET) film from the viewpoint of light transmission and cost.

<Manufacturing method of this flexible image display device member>
The method for manufacturing the flexible image display device member is not particularly limited, and as described above, the resin composition for forming the adhesive layer may be applied onto the flexible member to form the flexible image display device member in advance. After forming into a sheet using the resin composition, it may be bonded to a flexible member.

<< This image display device >>
By incorporating the present laminate, for example, by laminating the present laminate on another image display device constituent member, it is possible to form an image display device (also referred to as "the present image display device") provided with the present laminate. can.
In particular, the present laminated body can prevent delamination and cracking of the laminated sheet even when folded in an environment of low temperature and high temperature, and has good resilience, so that a flexible image display device can be formed.

The flexible image display device is more specifically a member capable of being fixed to a curved shape having a bending radius of 25 mm or more, particularly, for repeated bending actions with a bending radius of less than 25 mm, more preferably a bending radius of less than 3 mm. An image display device made of a member that can withstand.

Examples of the other image display device components include the above-mentioned optical films such as a cover lens protective film, a cover lens, a polarizing film, and a retardation film, a liquid crystal material, and a flexible member such as a backlight panel.

<< Explanation of words and phrases >>
In the present invention, the term "film" shall include a "sheet", and the term "sheet" shall include a "film".
Further, when the term "panel" is used, such as an image display panel or a protective panel, it includes a plate, a sheet, and a film.

In the present specification, when "X to Y" (X, Y are arbitrary numbers) is described, it means "X or more and Y or less" and "preferably larger than X" or "preferably larger than X", unless otherwise specified. It also includes the meaning of "smaller than Y".
Further, when described as "X or more" (X is an arbitrary number), it includes the meaning of "preferably larger than X" and is described as "Y or less" (Y is an arbitrary number). In this case, unless otherwise specified, it also includes the meaning of "preferably smaller than Y".

The present invention will be further described with reference to the following examples. However, the examples are not intended to limit the invention in any way.

<Raw materials>
(A-1): Acrylic polymer Akrit 6HY-3030 (Taisei Fine Chemical Co., Ltd. trade name, copolymer of butyl acrylate and 2-hydroxyethyl acrylate, mass average molecular weight: about 600,000, hydroxyl value 24 [KOH · mg] / G])

(A & B): Acrylic polymer-graft-polyurethane (a copolymer of butyl acrylate and 2-hydroxyethyl acrylate is used as a stem polymer, and polyurethane having a molecular weight of 8600 (one-ended acryloyl group) is contained in an amount of 1.2 wt% as a graft chain. Acrylic polymer, mass average molecular weight: about 700,000)

(B-1): Polyurethane composed of acryloyl group-terminated polyurethane (hexamethylene diisocyanate (HDI) and polypropylene glycol (PPG), polyurethane having hydroxyethyl acrylate (HEA) added to both ends, mass average molecular weight: about 8,000. , PPG mass ratio (polyurethane 100 wt%): approx. 69 wt%)

(B-2): OH group-terminated polyurethane (hexamethylene diisocyanate (HDI) 19 wt%, isophorone diisocyanate 5 wt%, polypropylene glycol (PPG) 76 wt%, mass average molecular weight: about 600,000)

(C); Other resin: Urethane acrylate: Shikou UV-3700B (Mitsubishi Chemical Corporation trade name, bifunctional urethane acrylate)

(D): Photopolymerization Initiator Esacure TZT (IGM, Photopolymerization Initiator, Mixture of 2,4,6-trimethylbenzophenone and 4-Methylbenzophenone)

(E): Cross-linking agent Coronate L; manufactured by Tosoh Corporation, isocyanate-based cross-linking agent (F): catalyst Nacella aluminum; acetylacetone metal complex, manufactured by Nippon Chemical Industry Co., Ltd.

<Manufacturing method of adhesive sheet>
The coating liquid was adjusted by uniformly mixing the mixture so as to have the composition (solid content) shown in Table 1 and adding ethyl acetate so that the solid content was 30 wt%.
Next, a liquid was developed on a mold-released polyethylene terephthalate film (Mitsubishi Chemical Corporation, Diafoil MRV (V03) thickness: 100 μm) using a bird film applicator manufactured by Elcometer, and the temperature was 90 ° C. It was dried in the oven for 10 minutes.

Regarding Example 5 and Comparative Example 1, a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, Diafoil MRQ thickness: 50 μm) which was heat-crosslinked by heat treatment at 120 ° C. for 3 minutes and then released from above. Was laminated with a hand roll and cured at 50 ° C. for 24 hours to obtain an adhesive sheet sandwiched between the release films.

On the other hand, for Examples 1 to 4 and Comparative Example 2 containing a photopolymerization initiator, a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Co., Ltd., diafoil MRQ thickness: 50 μm) that has been dried and then mold-released is hand-rolled. In a state where both sides were laminated with a release PET film, UV of 0.7 J / cm ² was irradiated with a high-pressure mercury lamp to cure the film.

The thickness of the adhesive sheet was set as shown in Table 1 by adjusting the gap of each applicator.

<Evaluation test of adhesive sheet>
(Gel fraction)
The following measurements were carried out for the adhesive sheets prepared in Examples and Comparative Examples from which the release film was removed.
1) Weigh about 150 mg of the adhesive sheet (W1) and wrap it in a 200 mesh SUS (stainless steel) mesh (W0) that has been weighed in advance.
2) Immerse the SUS mesh in 100 mL of ethyl acetate for 24 hours.
3) Take out the SUS mesh and dry it at 75 ° C. for 4 and a half hours.
4) Obtain the mass (W2) after drying, and measure the gel fraction of the pressure-sensitive adhesive sheet from the following formula.
Gel fraction (%) = 100 × (W2-W0) / W1

(Surface HSP, HSP distance (Ra))
The HSP on the surface of the adhesive sheet was measured as follows.
The release PET film of the adhesive sheet is peeled off on one side to expose the adhesive sheet, and a droplet of 2.0 μL of 11 kinds of HSP-known solvents is dropped onto the adhesive sheet, and the contact angle after 30 seconds is recorded, and the contact angle value is recorded. From, γ _SL is calculated from the Young-Dupre equation and the Hata / Kitazaki and Extended Hawks equations, and the relationship between the Hansen solubility parameter and surface tension (Equation 1) (Hansen Solubility Parameters 50 ^th anniversary conference, preprint 2017 PP.14 From -21 (2017)), it is determined that Ra and (γ _SL / (V _L ^1/3 )) ^1/2 are most correlated.
(Equation 1) δd ² + δp ² + 0.068 δh ² = 13.9γ _SL (1 / (V _L ^1/3 ))

Further, regarding the surface of the member sheet, the HSP was determined by the same procedure. The results are shown in Table 1.
Further, the HSP distance (Ra) was calculated from the values of the surface HSP of the adhesive sheet and the surface HSP of the member sheet measured above.

(Dynamic viscoelasticity)
By peeling off the release films on both sides of the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples and stacking a plurality of pressure-sensitive adhesive sheets, a sheet having a thickness of about 0.8 mm was produced and punched into a circle with a diameter of 8 mm. Adhesive jig: Φ8mm parallel plate, distortion: 0.1%, frequency: 1Hz, temperature: -70-100 ° C using a reometer (DHR-2, manufactured by TA Instruments Japan Co., Ltd.) The storage elastic modulus (G'), the loss elastic modulus (G "), and the loss tangent (tan δ) of the pressure-sensitive adhesive sheet were obtained by measuring under the condition of temperature rising rate: 3 ° C./min. The results are shown in Table 1. show.

(Recovery characteristics)
The adhesive sheets obtained in Examples and Comparative Examples were cut into strips having a length of 70 mm and a width of 10 mm, and paper was attached to both sides of 10 mm × 10 mm at both ends to use them as handles. (The part without a handle is 50 mm long x 10 mm wide)
Grasp the handle, extend it in the longitudinal direction until it becomes four times the distance between the handles (200 mm), hold it for 10 minutes, then release one end and measure the length after 20 minutes, as shown below. Judged.

〇: The length between the handles after the test is 1.0 to 1.6 times the initial length.
X: The length between the handles after the test is more than 1.6 times the initial length.

<Manufacturing of laminated body>
One of the release films of the pressure-sensitive adhesive sheets produced in Examples and Comparative Examples was peeled off, the pressure-sensitive adhesive sheet was rolled and bonded to a CPI (50 μm) manufactured by KOLON, and the remaining mold-release film was peeled off, and the other release film was peeled off. The manufactured CPI (50 μm) was attached to the pressure-sensitive adhesive sheet. This laminated body was autoclaved (60 ° C., gauge pressure 0.2 MPa, 20 minutes) and finished and pasted to obtain a laminated body.
In Example 4, as the member sheet, a member sheet in which the surface of the CPI manufactured by KOLON was subjected to O ₂ plasma treatment was used.

(Dynamic bending test Dynamic Folding)
The obtained laminate was cut into 40 mm × 100 mm to prepare a sample for evaluation of bending storage property. The evaluation sample was repeatedly U-shaped bent according to IEC 63715 using DLDMLH-FS manufactured by Yuasa System. The test conditions were −30 ° C., frequency 1 Hz, radius of curvature r: 3 mm, 100,000 cycles, and the bendability was evaluated according to the following criteria.
◯: No change in appearance is observed in the laminated body after bending 100,000 times.
X: After bending 100,000 times, abnormalities such as breakage, peeling (delamination), air bubbles, and foaming are observed in the laminated body.

(Haze)
A laminate prepared by laminating member sheets on both sides was used as an evaluation sample. The haze value was measured using a haze meter (“NDH5000” manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with JIS K7136. The results are shown in Table 1.

(Adhesive force)
CPI (50 μm) manufactured by KOLON is attached to the SUS plate as a member sheet with double-sided tape, and the release PET film of the adhesive sheet is peeled off on one side to expose the adhesive sheet, and one of the release films of the adhesive sheet is peeled off to form a backing film. A polyethylene terephthalate film (“Diafoil S-100” manufactured by Mitsubishi Chemical Co., Ltd., thickness 50 μm) was roll-bonded with a hand roller. This was cut into strips having a width of 25 mm and a length of 150 mm, and the remaining release film was peeled off and the exposed adhesive surface was rolled and attached to a CPI (50 μm) manufactured by KOLON as a member sheet using a hand roller. The member sheet surface is attached to a SUS plate with double-sided tape to create a laminate consisting of a SUS plate / double-sided tape / member sheet (CPI) / adhesive sheet / backing film (PET), and the laminate is autoclaved (60 ° C.). , Gauge pressure 0.2 MPa, 20 minutes), and finish-pasted to prepare a sample for measuring the adhesive force between the adhesive sheet / member sheet.

While pulling the backing film at an angle of 180 ° at a peeling speed of 300 mm / min, the backing film is peeled from the member sheet, the tensile strength is measured with a load cell, and the 180 ° peel strength of the adhesive sheet with respect to the member sheet. (N / 25 mm) was measured. Table 1 shows the results.

Table 1 shows the adhesive sheet formulation, the gel fraction of the adhesive sheet, the dynamic viscoelasticity of the adhesive sheet, the surface HSP of the adhesive sheet, the HSP distance between the adhesive sheet and the member sheet, the adhesive strength, and the results of the dynamic bending test. rice field.

From Table 1, the formulation containing both the acrylic component segment and the urethane component segment (Examples 1 to 5) was able to achieve both recovery characteristics and adhesive strength.
Further, it was confirmed that when the urethane component segment was contained, δp and δh tended to be larger, and the HSP distance from the member sheet tended to be smaller.
It was suggested that the adhesive strength at 60 ° C was affected by both G'(60 ° C) and HSP distance. In particular, it was found that those containing the photopolymerizable urethane component of Examples 1 to 3 had a good balance of performance including haze.
In another test, instead of (B-1) in Example 3, polycaprolactone type polyurethane (dicyclohexylmethanediisocyanate 47.8 wt%, polycaprolactone 34.8 wt%, neopentyl glycol 4.2 wt%, 1,4 -When an oligomer having a composition of 13.2 wt% butanediol) was used, the urethane component segment such as polycaprolactone type and the acrylic component segment were incompatible, and the haze was aggravated. On the other hand, the polyether component segment and the acrylic component segment were found to have a certain degree of compatibility, and based on the above results, it was found that they are adhesive sheets and laminates that can be suitably used for image display devices. rice field.

Claims (29)

A urethane polymer chain having a molecular chain having a urethane bond derived from a polyether polyol component and an isocyanate component (hereinafter referred to as "urethane component segment") and
It has an acrylic polymer chain (hereinafter referred to as "acrylic component segment") having a molecular chain derived from the (meth) acrylic acid alkyl ester component, and the mass average molecular weight (Mw) of the acrylic polymer is 400,000 to 1.3 million. Contains some adhesive,
An adhesive sheet that satisfies the following (I) and (II).
(I) The storage elastic modulus (G'(-20 ° C.)) at −20 ° C. obtained by dynamic viscoelasticity measurement in a shear mode with a frequency of 1 Hz is 300 kPa or less.
(II) The storage elastic modulus (G'(60 ° C.)) at 60 ° C. obtained by dynamic viscoelasticity measurement in a shear mode with a frequency of 1 Hz is 10 kPa or more. The pressure-sensitive adhesive sheet according to claim 1, wherein the polyether polyol contains a component derived from polyether glycol. The pressure-sensitive adhesive sheet according to claim 2, wherein the mass ratio (mass%) of the component derived from the polyether glycol is larger than the mass ratio (mass%) of the component derived from the isocyanate. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive is a urethane component segment and an acrylic component segment bonded by a covalent bond. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive contains one or more of the polymers according to any one of the following (a) to (c).
(A) Block polymer in which the urethane component segment and the acrylic component segment form a main chain (b) A graft polymer in which the urethane component segment or the acrylic component segment constitutes the main chain and the other segment constitutes the side chain. (C) A crosslinked polymer in which one of the urethane component segment or the acrylic component segment and the other segment are crosslinked. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive is formed from a pressure-sensitive adhesive composition containing any one or more of the following (d) and (e).
(D) Acrylic polymer and polyether type polyurethane (e) A mixture of monomer components constituting the acrylic polymer or a partial polymer thereof and a polyether type polyurethane The pressure-sensitive adhesive sheet according to claim 6, wherein the pressure-sensitive adhesive composition is a light or thermosetting pressure-sensitive adhesive composition that is cured by light or heat. The pressure-sensitive adhesive sheet according to claim 6 or 7, wherein the polyether type polyurethane has a (meth) acryloyl group or a hydroxyl group. The pressure-sensitive adhesive sheet according to any one of claims 1 to 8, wherein the pressure-sensitive adhesive contains an initiator and / or a cross-linking agent. The adhesive sheet according to any one of claims 1 to 9, wherein the haze is less than 1.0%. The adhesive sheet according to any one of claims 1 to 10, further satisfying (III).
(III) Pull both ends of the adhesive sheet in the opposite direction to extend it to four times the initial length, hold it for 10 minutes, then release one end and the length after 20 minutes has passed. It is 1.0 to 1.6 times the initial length. In the Hansen solubility parameter (δd, δp, δh) of the adhesive sheet surface measured by the contact angle method, the polar term δp is 2.0 MPa0.5 or more and the hydrogen bond term δh is 5.0 MPa0.5 or more. The adhesive sheet according to any one of claims 1 to 11. A urethane polymer chain having a molecular chain having a urethane bond derived from a polyether polyol component and an isocyanate component (hereinafter referred to as "urethane component segment") and
The acrylic having a molecular chain derived from a (meth) acrylic acid alkyl ester component and having an acrylic polymer chain having a mass average molecular weight (Mw) of 400,000 to 1.3 million (hereinafter referred to as "acrylic component segment"). An adhesive component used in a flexible device, which comprises an adhesive having a polymer mass average molecular weight (Mw) of 400,000 to 1.3 million. The adhesive component used in the flexible device according to claim 13, wherein the polyether polyol contains a component derived from polyether glycol. The adhesive component used for the flexible device according to claim 14, wherein the mass ratio (mass%) of the component derived from the polyether glycol is larger than the mass ratio (mass%) of the component derived from the isocyanate. The adhesive component is an adhesive component used for a flexible device according to any one of claims 13 to 15, wherein the urethane component segment and the acrylic component segment are covalently bonded. The pressure-sensitive adhesive component according to any one of claims 13 to 16, wherein the pressure-sensitive adhesive contains one or more of the polymers according to any one of the following (a) to (c).
(A) Block polymer in which the urethane component segment and the acrylic component segment form a main chain (b) A graft polymer in which the urethane component segment or the acrylic component segment constitutes the main chain and the other segment constitutes the side chain. (C) A crosslinked polymer in which one of the urethane component segment or the acrylic component segment and the other segment are crosslinked. The pressure-sensitive adhesive is used in the flexible device according to any one of claims 13 to 16, which comprises a cured product of a pressure-sensitive adhesive composition containing any one or more of the following (d) and (e). Adhesive parts to be used.
(D) Acrylic polymer and polyether type polyurethane (e) A mixture of monomer components constituting the acrylic polymer or a partial polymer thereof and a polyether type polyurethane The pressure-sensitive adhesive component used in the flexible device according to claim 18, wherein the pressure-sensitive adhesive composition is a light or thermosetting pressure-sensitive adhesive composition that is cured by light or heat. The adhesive component used for the flexible device according to claim 18 or 19, wherein the polyether type polyurethane has a (meth) acryloyl group and / or a hydroxyl group. The pressure-sensitive adhesive component used in the flexible device according to any one of claims 13 to 20, wherein the pressure-sensitive adhesive contains an initiator and / or a cross-linking agent. A flexible image display device member having a structure in which two flexible members are bonded together via an adhesive layer.
The Hansen solubility parameter δp on the surface of at least one of the two flexible members is 10.0 MPa0.5 or more and 20.0 MPa0.5 or less.
The adhesive layer has a urethane polymer chain (hereinafter referred to as "urethane component segment") having a molecular chain having a urethane bond derived from a polyether polyol component and an isocyanate component, and a molecular chain derived from a (meth) acrylic acid alkyl ester component. It contains an adhesive having an acrylic polymer chain (hereinafter referred to as “acrylic component segment”) and having a mass average molecular weight (Mw) of the acrylic polymer of 400,000 to 1.3 million.
The adhesive layer is a flexible image display device member that satisfies the following (I) and (II).
(I) The storage elastic modulus (G'(-20 ° C.)) at −20 ° C. obtained by dynamic viscoelasticity measurement in a shear mode with a frequency of 1 Hz is 300 kPa or less.
(II) The storage elastic modulus (G'(60 ° C.)) at 60 ° C. obtained by dynamic viscoelasticity measurement in a shear mode with a frequency of 1 Hz is 10 kPa or more. The flexible image display device member according to claim 22, wherein the adhesive layer with respect to the flexible member has a 180-degree peel strength at a peel rate of 300 mm / min at 60 ° C. of 8 N / 25 mm or more. A laminated body provided with a member sheet on at least one side of the adhesive sheet according to any one of claims 1 to 12.
A laminate in which the Hansen solubility parameter δp on the surface of the member sheet is 10.0 MPa0.5 or more and 20.0 MPa0.5 or less. A laminate having a member sheet on at least one side of the adhesive layer.
The adhesive layer has a urethane polymer chain (hereinafter referred to as "urethane component segment") having a molecular chain having a urethane bond derived from a polyether polyol component and an isocyanate component, and a molecular chain derived from a (meth) acrylic acid alkyl ester component. It contains an adhesive having an acrylic polymer chain (hereinafter referred to as “acrylic component segment”) and having a mass average molecular weight (Mw) of the acrylic polymer of 400,000 to 1.3 million.
Satisfying the following (I) and (II),
A laminate in which the Hansen solubility parameter δp on the surface of the member sheet is 10.0 MPa0.5 or more and 20.0 MPa0.5 or less.
(I) The storage elastic modulus (G'(-20 ° C.)) at −20 ° C. obtained by dynamic viscoelasticity measurement in a shear mode with a frequency of 1 Hz is 300 kPa or less.
(II) The storage elastic modulus (G'(60 ° C.)) at 60 ° C. obtained by dynamic viscoelasticity measurement in a shear mode with a frequency of 1 Hz is 10 kPa or more. The laminate according to claim 24 or 25, wherein the haze is less than 1.0%. The laminate according to any one of claims 24 to 26, wherein the pressure-sensitive adhesive sheet or the pressure-sensitive adhesive layer with respect to the member sheet has a 180-degree peel strength at a peeling speed of 300 mm / min at 60 ° C. of 8 N / 25 mm or more. The laminate according to any one of claims 24 to 27, wherein the member sheet is made of one or more resins selected from the group consisting of polyamide, polyimide, epoxy resin, triacetyl cellulose and polyester. An image display device comprising the laminate according to any one of claims 24 to 28.