JP6970850B2 - Display device and base material laminate - Google Patents

Description

The present invention relates to a display device configured to be foldable and a base material laminate used in such a display device.

An organic EL display device integrated with a touch sensor is conventionally known, for example, as shown in Patent Document 1. In the organic EL display device of Patent Document 1, as shown in FIG. 1, an optical laminate 920 is provided on the visual side of the organic EL display panel 901, and a touch panel 930 is provided on the visual side of the optical laminate 920. ing. The optical laminate 920 includes a polarizing element 921 to which protective films 922-1 and 922-2 are bonded on both sides and a retardation film 923, and the polarizing element 921 is provided on the visual recognition side of the retardation film 923. Further, in the touch panel 930, the transparent conductive films 916-1 and 916-2 having a structure in which the base films 915-1 and 915-2 and the transparent conductive layers 912-1 and 912-2 are laminated are interposed via the spacer 917. It has an arranged structure.

On the other hand, in recent years, it is expected to realize a foldable organic EL display device, which is an organic EL display device having more excellent portability.

Japanese Unexamined Patent Publication No. 2014-157745

However, the conventional organic EL display device as shown in Patent Document 1, for example, is not designed with bending in mind. If a plastic film is used as the base material of the organic EL display panel, the organic EL display panel can be given flexibility. However, a layer vulnerable to bending such as a transparent conductive layer included in a touch sensor member constituting a conventional organic EL display device, a thin film sealing layer of an organic EL display panel, and a hard coat layer provided on the surface of a window member. However, when the organic EL display device is bent, it breaks.

Therefore, an object of the present invention is to realize a display device that can prevent a layer or member vulnerable to bending from breaking due to bending of the display device in a display device configured to be bendable. do.

One aspect of the present invention includes an optical film member, a first adhesive layer, a window member laminated on one surface of the optical film member via the first adhesive layer, a second adhesive layer, and the optical. A foldable display device having a laminated structure including a panel member laminated on the other surface of the film member via the second adhesive layer, wherein the laminated structure is a surface on the second adhesive layer side. In addition, it has a layer that is more easily broken than the window member and the optical film member when bent and deformed, and the display device is bent at an angle of 180 ° with the window member on the outside and 180 °. A direction orthogonal to the bending radial direction generated on one surface of the optical film member when the display device is bent and deformed so that the distance between the outermost surfaces facing each other in parallel in the state of being bent at an angle is 4 mm. The difference between the strain of A and the strain in the direction perpendicular to the bending radial direction generated on the surface of the window member facing the first adhesive layer is A. The optical film member and the window are made of a single layer, bent at an angle of 180 °, and bent at an angle of 180 ° so as to be the same as when the members are made to do so. When bending deformation is caused so that the distance between the outermost surfaces of the members facing each other in parallel is 4 mm, the strain in the direction orthogonal to the bending radial direction generated on the outer surface of the optical film member and the above-mentioned The difference from the strain in the direction orthogonal to the bending radial direction generated on the inner surface of the window member is A', the display device is bent at an angle of 180 ° with the window member on the outside, and at an angle of 180 °. Strain in the direction orthogonal to the bending radial direction generated on the other surface of the optical film member when the display device is bent and deformed so that the distance between the outermost surfaces facing each other in parallel in the bent state is 4 mm. The difference from the strain in the direction perpendicular to the bending radial direction generated on the surface of the laminated structure facing the second adhesive layer is B, and the outside and the inside when bending and deforming bend and deform the display device. The optical film member and the laminated structure are each in a single layer state, bent at an angle of 180 °, and bent at an angle of 180 ° so as to be the same as the time. Bend deformation is generated so that the distance between the outermost surfaces facing each other in parallel of the body is 4 mm. The difference between the strain in the direction orthogonal to the bending radius direction generated on the inner surface of the optical film member and the strain in the direction orthogonal to the bending radius direction generated on the outer surface of the laminated structure when squeezed. When B', it was bent and deformed by allowing the following equations (1), (2) and (3) to hold between the strain differences A, A', B and B'. The display device 0.3 <A / A'<1.2 ... (1), wherein the elongation of the fragile layer is suppressed to a value smaller than the elongation at break.
B / B'<1.7A / A'-0.15 ... (2)
0 <B / B'<1.25 ... (3)
Is to provide.

The window member may have a hardcourt layer on the surface opposite to the first adhesive layer.

The optical film member can be a circularly polarizing functional film laminate in which a retardation film is laminated on a polarizing film.

The polarizing film may be a laminated body in which a polarizing element protective film is laminated on at least one surface of a polarizing element and a polarizing element.

The polarizing element protective film may contain an acrylic resin.

The layer that is more easily broken than the window member and the optical film member can be a thin film sealing layer formed on the surface of the panel member on the side of the second adhesive layer.

The laminated structure forms a thin film encapsulating layer on the surface of the panel member on the side of the second adhesive layer, and touches the surface of the thin film encapsulating layer on the opposite side of the panel member via the third adhesive layer. The sensor members are laminated to form a transparent conductive layer on the surface of the touch sensor member opposite to the panel member, and the transparent conductive layer is used as a layer that is more easily broken than the window member and the optical film member. It can be laminated on the second adhesive layer.

It can be assumed that the relationship of the following equation (4) further holds between the differences A and A'with the strain.
0.8 <A / A'・ ・ ・ ・ (4)

The shear modulus of the second adhesive layer can be larger than the shear modulus of the first adhesive layer.

A fourth adhesive layer may be further provided on the surface of the panel member opposite to the second adhesive layer, and the protective member may be laminated via the fourth adhesive layer.

The shear modulus of the fourth adhesive layer may be smaller than the shear modulus of the second adhesive layer and smaller than the shear modulus of the third adhesive layer.

One aspect of the present invention is used for the display device, the optical film member, the window member laminated on one surface of the optical film member via the first adhesive layer, and the optical film member. It provides a base material laminate having a touch sensor member including the transparent conductive layer laminated on the other surface via the second adhesive layer.

According to the present invention, in a display device configured to be bendable, it is possible to realize a display device capable of suppressing breakage of a layer or member vulnerable to bending due to bending of the display device.

Hereinafter, embodiments of the display device according to the present invention will be described in detail with reference to the drawings.

It is sectional drawing which shows the conventional organic EL display device. It is sectional drawing which shows the display device by one Embodiment of this invention. It is sectional drawing which shows the display device by another embodiment of this invention. It is a figure which shows the manufacturing method of the retardation film used in one Example. It is a figure which shows the simulation method which concerns on embodiment of this invention. It is a figure explaining the strain orthogonal to the bending radius direction. It is a figure which shows the strain distribution in the stacking direction of an Example and a comparative example in which the shear elastic modulus G'of the 2nd adhesive layer was changed. It is a figure which shows the strain distribution in the stacking direction of the Example which changed the shear elastic modulus G'of the third adhesive layer. It is a figure which shows the strain distribution in the stacking direction of the Example which changed the shear elastic modulus G'of the 4th adhesive layer. It is a figure which shows the strain distribution in the stacking direction of the Example which changed the shear elastic modulus G'of the first adhesive layer. It is a figure which shows the relationship between A / A'and B / B'. It is a figure which shows the evaluation method of a crack.

[Optical film member]
The optical film member used in the display device of the present invention includes a polarizing element, a polarizing film, a film such as a protective film or a retardation film formed of a transparent resin material, and a part or a combination thereof, particularly a polarizing film. A circularly polarized light functional film laminate in which a retardation film is laminated can be used. The optical film member does not include an adhesive layer such as the first adhesive layer described later.

The thickness of the optical film member is preferably 92 μm or less, more preferably 60 μm or less, and further preferably 10 to 50 μm. If it is within the above range, it is a preferable embodiment without inhibiting bending.
<Polarizer>
As the polarizing element contained in the optical film member of the present invention, a polyvinyl alcohol (PVA) -based resin in which iodine is oriented, which has been stretched by a stretching step such as an air stretching (dry stretching) or a boric acid water stretching step, can be used. can.

As a method for producing a polarizing element, a production method including a step of dyeing a single layer of a PVA-based resin and a step of stretching, as described in Japanese Patent Application Laid-Open No. 2004-341515 (single-layer stretching method). ). Further, JP-A No. 51-06644, JP-A-2000-338329, JP-A-2001-343521, International Publication No. 2010/100917, JP-A-2012-073563, JP-A-2011-2816. A production method including a step of stretching a PVA-based resin layer and a resin base material for stretching in a laminated state and a step of dyeing, as described in 1. With this manufacturing method, even if the PVA-based resin layer is thin, it can be stretched without any trouble such as breakage due to stretching because it is supported by the stretching resin base material.

The thickness of the polarizing element is 20 μm or less, preferably 12 μm or less, more preferably 9 μm or less, still more preferably 1 to 8 μm, and particularly preferably 3 to 6 μm. If it is within the above range, it is a preferable embodiment without inhibiting bending.

<Polarizing film>
As long as the characteristics of the present invention are not impaired, the polarizing element may have a polarizing element protective film bonded to at least one side by an adhesive (layer) (not shown in the drawings). An adhesive can be used for the bonding process between the polarizing element and the polarizing element protective film. Examples of the adhesive include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based adhesives, and water-based polyesters. The adhesive is usually used as an adhesive consisting of an aqueous solution and usually contains 0.5 to 60% by weight of a solid content. In addition to the above, examples of the adhesive between the decoder and the protector protective film include an ultraviolet curable adhesive, an electron beam curable adhesive, and the like. The adhesive for an electron beam curable polarizing film exhibits suitable adhesiveness to the above-mentioned various polarizing element protective films. Further, the adhesive used in the present invention may contain a metal compound filler. In the present invention, a polarizing film in which a polarizing element and a polarizing element protective film are bonded together with an adhesive (layer) may be referred to as a polarizing film.

<Phase difference film>
The optical film member used in the present invention may include a retardation film, and the retardation film used is one obtained by stretching a polymer film or one in which a liquid crystal material is oriented and immobilized. Can be done. As used herein, a retardation film refers to a film having birefringence in the in-plane and / or thickness direction.

Examples of the retardation film include an antireflection retardation film (see JP-A-2012-133303 [0221], [0222], and [0228]) and a retardation film for viewing angle compensation (Japanese Patent Laid-Open No. 2012-133303 [Japanese Patent Laid-Open No. 2012-133303]. 0225], [0226]), tilt-oriented retardation film for viewing angle compensation (see Japanese Patent Application Laid-Open No. 2012-133303 [0227]) and the like.

The retardation film is not particularly limited as long as it has substantially the above-mentioned functions, for example, the retardation value, the arrangement angle, the three-dimensional birefringence, and whether it is a single layer or a multilayer, and is a known retardation film. Can be used.

The thickness of the retardation film is preferably 20 μm or less, more preferably 10 μm or less, still more preferably 1 to 9 μm, and particularly preferably 3 to 8 μm. If it is within the above range, it is a preferable embodiment without inhibiting bending.

As used herein, Re [550] refers to an in-plane phase difference value measured with light having a wavelength of 550 nm at 23 ° C. In Re [550], the refractive indexes in the slow axis direction and the phase advance axis direction of the retardation film at a wavelength of 550 nm are nx and ny, respectively, and d (nm) is the thickness of the retardation film. It can be obtained by [550] = (nx-ny) × d. The slow-phase axis refers to the direction in which the in-plane refractive index becomes maximum.

The in-plane birefringence Δn, which is nx-ny of the present invention, is 0.002 to 0.2, preferably 0.0025 to 0.15.

In the above retardation film, the in-plane retardation value (Re [550]) measured with light having a wavelength of 550 nm is preferably the in-plane retardation value (Re [450]) measured with light having a wavelength of 450 nm, preferably at 23 ° C. ]) Greater than. When the ratio of the retardation film having such a wavelength dispersion characteristic is in this range, the longer the wavelength, the more the retardation appears, and the ideal retardation characteristic can be obtained at each wavelength in the visible region. For example, when used for an organic EL display, a circularly polarizing plate or the like can be produced by producing a retardation film having such a wavelength dependence as a 1/4 wave plate and bonding it with a polarizing plate. It is possible to realize a neutral polarizing plate and a display device with less wavelength dependence of hue. On the other hand, when the ratio is out of this range, the wavelength dependence of the reflected hue becomes large, and a problem of coloring occurs in the polarizing plate and the display device.

The ratio of Re [550] to Re [450] (Re [450] / Re [550]) of the retardation film is 0.8 or more and less than 1.0, more preferably 0.8 to 0.95. ..

In the above retardation film, the in-plane retardation value (Re [550]) measured with light having a wavelength of 550 nm is preferably the in-plane retardation value (Re [650]) measured with light having a wavelength of 650 nm, preferably at 23 ° C. ]) Is smaller than. A retardation film having such wavelength dispersion characteristics has a constant retardation value in the red region. For example, when used in a liquid crystal display device, a phenomenon that light leakage occurs depending on the viewing angle and a red display image are displayed. It is possible to improve the phenomenon of taking on a taste (also called the redish phenomenon).

The ratio of Re [650] to Re [550] (Re [550] / Re [650]) of the retardation film is 0.8 or more and less than 1.0, preferably 0.8 to 097. By setting Re [550] / Re [650] in the above range, for example, when the retardation film is used for an organic EL display, even better display characteristics can be obtained.

Re [450], Re [550], and Re [650] can be measured using the product name "AxoScan" manufactured by Axometrics.

In one embodiment, the retardation film of the present invention is produced by stretching a polymer film to orient it.

As a method for stretching the polymer film, any appropriate stretching method can be adopted depending on the purpose. Examples of the stretching method suitable for the present invention include a horizontal uniaxial stretching method, a vertical and horizontal simultaneous biaxial stretching method, and a vertical and horizontal sequential biaxial stretching method. As the stretching means, any suitable stretching machine such as a tenter stretching machine, a biaxial stretching machine and the like can be used. Preferably, the stretching machine is provided with temperature control means. When the stretching is performed by heating, the internal temperature of the stretching machine may be continuously changed or may be continuously changed. The process may be divided into one time or two or more times. The stretching direction is preferably the film width direction (TD direction) or the diagonal direction.

In another embodiment, as the retardation film of the present invention, a retardation film formed by aligning and immobilizing a liquid crystal material can be used. Each retardation layer can be an orientation solidification layer of a liquid crystal compound. By using a liquid crystal compound, the difference between nx and ny of the obtained retardation layer can be significantly increased as compared with the non-liquid crystal material, so that the thickness of the retardation layer for obtaining a desired in-plane retardation can be obtained. Can be made much smaller. As a result, it is possible to further reduce the thickness of the circularly polarizing plate (eventually, the organic EL display device). As used herein, the term "aligned solidified layer" refers to a layer in which a liquid crystal compound is oriented in a predetermined direction within the layer and the oriented state is fixed. In the present embodiment, the rod-shaped liquid crystal compounds are typically oriented in a state of being aligned in the slow axis direction of the retardation layer (homogeneous orientation). Examples of the liquid crystal compound include a liquid crystal compound (nematic liquid crystal) in which the liquid crystal phase is a nematic phase. As such a liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer can be used. The liquid crystal expression mechanism of the liquid crystal compound may be either lyotropic or thermotropic. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination.

When the liquid crystal compound is a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer and a crosslinkable monomer. This is because the orientation state of the liquid crystal monomer can be fixed by polymerizing or cross-linking the liquid crystal monomer. After the liquid crystal monomers are oriented, for example, the liquid crystal monomers are polymerized or crosslinked with each other, whereby the oriented state can be fixed. Here, the polymer is formed by polymerization, and the three-dimensional network structure is formed by crosslinking, but these are non-liquid crystal. Therefore, the formed retardation layer does not undergo a transition to a liquid crystal phase, a glass phase, or a crystal phase due to a temperature change peculiar to a liquid crystal compound, for example. As a result, the retardation layer becomes an extremely stable retardation layer that is not affected by temperature changes.

The temperature range in which the liquid crystal monomer exhibits liquid crystallinity differs depending on the type. Specifically, the temperature range is preferably 40 ° C. to 120 ° C., more preferably 50 ° C. to 100 ° C., and most preferably 60 ° C. to 90 ° C.

As the liquid crystal monomer, any suitable liquid crystal monomer can be adopted. For example, the polymerizable mesogen compounds described in Special Tables 2002-533742 (WO00 / 37585), EP358208 (US5211877), EP66137 (US43884553), WO93 / 22397, EP0261712, DE19504224, DE4408171, and GB2280445 can be used. Specific examples of such a polymerizable mesogen compound include, for example, BASF's trade name LC242, Merck's trade name E7, and Wacker-Chem's trade name LC-Silicon-CC3767. As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferable.

Orientation of liquid crystal compound In the solidified layer, the surface of a predetermined base material is subjected to an orientation treatment, and a coating liquid containing the liquid crystal compound is applied to the surface to orient the liquid crystal compound in a direction corresponding to the orientation treatment. It can be formed by fixing the orientation state. In one embodiment, the substrate is any suitable resin film and the oriented solidified layer formed on the substrate can be transferred to the surface of the substituent. At this time, the angle formed by the absorption axis of the polarizing element and the slow axis of the liquid crystal oriented solidified layer is arranged so as to be 15 °. Further, the phase difference of the liquid crystal oriented solidified layer is λ / 2 (about 270 nm) with respect to the wavelength of 550 nm. Further, as described above, a liquid crystal oriented solidified layer having a wavelength of λ / 4 (about 140 nm) for a wavelength of 550 nm is formed on a transferable substrate, and 1 / of the laminate of the polarizing element and the 1/2 wave plate. It is laminated on the two-wave plate side so that the angle formed by the absorption axis of the polarizing element and the slow axis of the 1/4 wave plate is 75 °.

<Polarizer protective film>
The polarizing element protective film formed from the transparent resin material used in the display device of the present invention includes cycloolefin resins such as norbornene resins, olefin resins such as polyethylene and polypropylene, polyester resins, (meth) acrylic resins and the like. Can be used.

The thickness of the polarizing element protective film is preferably 5 to 60 μm, more preferably 10 to 40 μm, still more preferably 10 to 30 μm, and a surface treatment layer such as an antiglare layer or an antireflection layer is appropriately provided. Can be provided. If it is within the above range, it is a preferable embodiment without inhibiting bending.
The transmission humidity of the polarizing element protective film used in the optical laminate of the present invention is 200 g / m ² or less, preferably 170 g / m ² or less, more preferably 130 g / m ² or less, and particularly preferably 90 g / m ² or less. ..

[Window member]
The window member is arranged on the outermost surface on the visual side of the display device in order to prevent damage to the optical film member, the touch sensor member, and the panel member.

The window member usually comprises a window film or window glass. The window film or window glass may be provided with a hard coat layer. Examples of the window glass include a thin glass substrate. Optical laminates applied to foldable display devices are required to have high flexibility, high transparency, and high hardness. The material of the window film is not particularly limited as long as it satisfies these physical characteristics.

<Window film>
Examples of the window film include a transparent resin film. Examples of the resin constituting the transparent resin film include a polyimide resin, a polyamide resin, a polyester resin, a cellulose resin, an acetate resin, a styrene resin, a sulfone resin, an epoxy resin, a polyolefin resin, and a polyether. At least one selected from ether ketone resin, sulfide resin, vinyl alcohol resin, urethane resin, acrylic resin, and polycarbonate resin can be mentioned. However, the resin constituting the transparent resin film is not limited to these.

<Hard coat layer>
The hardcoat layer is formed by applying a curable coating agent to the surface of an underlying layer (for example, a window film) and curing it.

As the coating agent, for example, those used for optical films can be used. Examples of the coating agent include, but are not limited to, an acrylic coating agent, a melamine coating agent, a urethane coating agent, an epoxy coating agent, a silicone coating agent, and an inorganic coating agent.

The coating agent may contain additives. Additives include, for example, silane coupling agents, colorants, dyes, powders or particles (pigments, inorganic or organic fillers, particles of inorganic or organic materials, etc.), surfactants, plasticizers, antistatic agents. Examples thereof include, but are not limited to, agents, surface lubricants, leveling agents, antioxidants, light stabilizers, ultraviolet absorbers, polymerization inhibitors, antifouling materials, and the like.

[First adhesive layer]
The first adhesive layer used in the display device of the present invention is formed by laminating a window member on one surface of an optical film member.
The pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer used in the display device of the present invention includes an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a vinyl alkyl ether-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, and a polyamide-based pressure-sensitive adhesive. Examples thereof include agents, urethane-based adhesives, fluorine-based adhesives, epoxy-based adhesives, and polyether-based adhesives. The pressure-sensitive adhesive constituting the first pressure-sensitive adhesive layer may be used alone or in combination of two or more. However, from the viewpoints of transparency, processability, durability, adhesion, bending resistance, etc., it is preferable to use the acrylic pressure-sensitive adhesive alone.

<(Meta) acrylic polymer>
When an acrylic pressure-sensitive adhesive is used as the pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer, a (meth) acrylic-based monomer having a linear or branched alkyl group having 1 to 24 carbon atoms as a monomer unit. It is preferable to contain a (meth) acrylic polymer containing. By using the linear or branched (meth) acrylic monomer having an alkyl group having 1 to 24 carbon atoms, an adhesive layer having excellent flexibility can be obtained. The (meth) acrylic polymer in the present invention means an acrylic polymer and / or a methacrylic polymer, and the (meth) acrylate means an acrylate and / or a methacrylate.

Specific examples of the (meth) acrylic monomer having a linear or branched alkyl group having 1 to 24 carbon atoms constituting the main skeleton of the (meth) acrylic polymer include methyl (meth) acrylate and ethyl. (Meta) acrylate, n-butyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, n -Hexyl (meth) acrylate, isohexyl (meth) acrylate, isoheptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, Examples thereof include isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, and n-tetradecyl (meth) acrylate. In general, a monomer having a low glass transition temperature (Tg) becomes a viscoelastic body even in a high velocity region at the time of bending. Therefore, from the viewpoint of flexibility, a linear or branched alkyl having 4 to 8 carbon atoms. A (meth) acrylic monomer having a group is preferable. As the (meth) acrylic monomer, one kind or two or more kinds can be used.

The linear or branched (meth) acrylic monomer having an alkyl group having 1 to 24 carbon atoms is the main component of all the monomers constituting the (meth) acrylic polymer. Here, the main component is 80 to 100% by weight of a (meth) acrylic monomer having a linear or branched alkyl group having 1 to 24 carbon atoms among all the monomers constituting the (meth) acrylic polymer. %, More preferably 90 to 100% by weight, even more preferably 92 to 99.9% by weight, and particularly preferably 94 to 99.9% by weight.

When an acrylic pressure-sensitive adhesive is used as the pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer, it is preferable to contain a (meth) acrylic polymer containing a hydroxyl group-containing monomer having a reactive functional group as a monomer unit. .. By using the hydroxyl group-containing monomer, an adhesive layer having excellent adhesion and flexibility can be obtained. The hydroxyl group-containing monomer is a compound containing a hydroxyl group in its structure and containing a polymerizable unsaturated double bond such as a (meth) acryloyl group and a vinyl group.

Specific examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, and 8-hydroxy. Examples thereof include hydroxyalkyl (meth) acrylates such as octyl (meth) acrylates, 10-hydroxydecyl (meth) acrylates and 12-hydroxylauryl (meth) acrylates, and (4-hydroxymethylcyclohexyl) -methyl acrylates. Among the hydroxyl group-containing monomers, 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferable from the viewpoint of durability and adhesion. As the hydroxyl group-containing monomer, one kind or two or more kinds can be used.

Further, as the monomer unit constituting the (meth) acrylic polymer, it is possible to contain a monomer such as a carboxyl group-containing monomer having a reactive functional group, an amino group-containing monomer, and an amide group-containing monomer. The use of these monomers is preferable from the viewpoint of adhesion in a moist heat environment.

When an acrylic pressure-sensitive adhesive is used as the pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer, a (meth) acrylic polymer containing a carboxyl group-containing monomer having a reactive functional group can be contained as a monomer unit. .. By using the carboxyl group-containing monomer, an adhesive layer having excellent adhesion in a moist heat environment can be obtained. The carboxyl group-containing monomer is a compound containing a carboxyl group in its structure and containing a polymerizable unsaturated double bond such as a (meth) acryloyl group and a vinyl group.

Specific examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid and the like.

When an acrylic pressure-sensitive adhesive is used as the pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer, a (meth) acrylic polymer containing an amino group-containing monomer having a reactive functional group can be contained as a monomer unit. .. By using the amino group-containing monomer, an adhesive layer having excellent adhesion in a moist heat environment can be obtained. The amino group-containing monomer is a compound containing an amino group in its structure and containing a polymerizable unsaturated double bond such as a (meth) acryloyl group and a vinyl group.

Specific examples of the amino group-containing monomer include N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate and the like.

When an acrylic pressure-sensitive adhesive is used as the pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer, a (meth) acrylic polymer containing an amide group-containing monomer having a reactive functional group can be contained as a monomer unit. .. By using the amide group-containing monomer, an adhesive layer having excellent adhesion can be obtained. The amide group-containing monomer is a compound containing an amide group in its structure and containing a polymerizable unsaturated double bond such as a (meth) acryloyl group and a vinyl group.

Specific examples of the amide group-containing monomer include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-isopropylacrylamide, N-methyl (meth) acrylamide, and N. -Butyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylol-N-propane (meth) acrylamide, aminomethyl (meth) acrylamide, aminoethyl (meth) acrylamide, mercapto Acrylamide-based monomers such as methyl (meth) acrylamide and mercaptoethyl (meth) acrylamide; N-acrylloyl heterocyclic monomers such as N- (meth) acryloylmorpholin, N- (meth) acryloylpiperidin, and N- (meth) acryloylpyrrolidine; Examples thereof include N-vinyl group-containing lactam-based monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam.

As the monomer unit constituting the (meth) acrylic polymer, the blending ratio (total amount) of the monomers having the reactive functional group is 20% by weight or less in all the monomers constituting the (meth) acrylic polymer. Is preferable, 10% by weight or less is more preferable, 0.01 to 8% by weight is further preferable, 0.01 to 5% by weight is particularly preferable, and 0.05 to 3% by weight is most preferable. If it exceeds 20% by weight, the number of cross-linking points increases and the flexibility of the pressure-sensitive adhesive (layer) is lost, so that the stress relaxation property tends to be poor.

As the monomer unit constituting the (meth) acrylic polymer, in addition to the monomer having a reactive functional group, other copolymerizable monomers can be introduced as long as the effects of the present invention are not impaired. The blending ratio is not particularly limited, but is preferably 30% by weight or less, and more preferably not contained, in all the monomers constituting the (meth) acrylic polymer. If it exceeds 30% by weight, the number of reaction points with the film tends to decrease, and the adhesion tends to decrease, especially when a material other than the (meth) acrylic monomer is used.

In the present invention, when the (meth) acrylic polymer is used, one having a weight average molecular weight (Mw) in the range of 1 million to 2.5 million is usually used. Considering durability, particularly heat resistance and flexibility, it is preferably 1.2 million to 2.2 million, more preferably 1.4 million to 2 million. When the weight average molecular weight is smaller than 1 million, in order to ensure durability, when cross-linking polymer chains, the number of cross-linking points is larger than that of a polymer chain having a weight average molecular weight of 1 million or more, and an adhesive (layer) is used. ) Is lost, so that the dimensional changes between the bending outer side (convex side) and the bending inner side (concave side) that occur between the films during bending cannot be alleviated, and the film is likely to break. Further, when the weight average molecular weight becomes larger than 2.5 million, a large amount of diluting solvent is required to adjust the viscosity for coating, which is not preferable because it increases the cost, and the obtained (meth) acrylic type. Since the entanglement of the polymer chains of the polymer becomes complicated, the flexibility is inferior and the film is liable to break at the time of bending. The weight average molecular weight (Mw) is a value measured by GPC (gel permeation chromatography) and calculated in terms of polystyrene.

For the production of such (meth) acrylic polymers, known production methods such as solution polymerization, bulk polymerization, emulsion polymerization, and various radical polymerizations can be appropriately selected. Further, the obtained (meth) acrylic polymer may be any of a random copolymer, a block copolymer, a graft copolymer and the like.

In the solution polymerization, for example, ethyl acetate, toluene and the like are used as the polymerization solvent. As a specific example of solution polymerization, a polymerization initiator is added under an inert gas stream such as nitrogen, and the polymerization is usually carried out at about 50 to 70 ° C. under reaction conditions of about 5 to 30 hours.

The polymerization initiator, chain transfer agent, emulsifier and the like used for radical polymerization are not particularly limited and can be appropriately selected and used. The weight average molecular weight of the (meth) acrylic polymer can be controlled by the amount of the polymerization initiator and the chain transfer agent used, and the reaction conditions, and the amount of the (meth) acrylic polymer used is appropriately adjusted according to these types.

Examples of the polymerization initiator include 2,2'-azobisisobutyronitrile, 2,2'-azobis (2-amidinopropane) dihydrochloride, and 2,2'-azobis [2- (5-methyl-). 2-imidazolin-2-yl) propane] dihydrochloride, 2,2'-azobis (2-methylpropionamidine) disulfate, 2,2'-azobis (N, N'-dimethyleneisobutyramidin), 2, Azo-based initiators such as 2'-azobis [N- (2-carboxyethyl) -2-methylpropionamidine] hydrate (trade name: VA-057, manufactured by Wako Pure Chemical Industries, Ltd.), potassium persulfate, Persulfate such as ammonium persulfate, di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxyneodeca Noate, t-hexylperoxypivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethyl Hexanoate, di (4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butylperoxyisobutyrate, 1,1-di (t-hexylperoxy) cyclohexane, t-butylhydroperoxide, peroxide Examples include peroxide-based initiators such as hydrogen, redox-based initiators in which a peroxide and a reducing agent such as a combination of persulfate and sodium hydrogen sulfite, and a combination of peroxide and sodium ascorbate are combined. Yes, but not limited to these.

The polymerization initiator may be used alone or in admixture of two or more, but the content as a whole is, for example, with respect to 100 parts by weight of all the monomers constituting the (meth) acrylic polymer. , 0.005 to 1 part by weight, more preferably about 0.02 to 0.5 part by weight.

Further, when a chain transfer agent, an emulsifier used for emulsion polymerization or a reactive emulsifier is used, conventionally known ones can be appropriately used. Further, the amount of these additions can be appropriately determined as long as the effects of the present invention are not impaired.

<Crosslinking agent>
The pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer may contain a cross-linking agent. As the cross-linking agent, an organic cross-linking agent or a polyfunctional metal chelate can be used. Examples of the organic cross-linking agent include an isocyanate-based cross-linking agent, a peroxide-based cross-linking agent, an epoxy-based cross-linking agent, and an imine-based cross-linking agent. A polyfunctional metal chelate is one in which a polyvalent metal is covalently or coordinated to an organic compound. Examples of the polyvalent metal atom include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti and the like. Can be mentioned. Examples of the atom in the organic compound to be covalently bonded or coordinated are an oxygen atom and the like, and examples of the organic compound include an alkyl ester, an alcohol compound, a carboxylic acid compound, an ether compound and a ketone compound. Among them, isocyanate-based cross-linking agents (particularly, trifunctional isocyanate-based cross-linking agents) are preferable in terms of durability, and peroxide-based cross-linking agents and isocyanate-based cross-linking agents (particularly, bifunctional isocyanate-based cross-linking agents) are preferable. Is preferable from the viewpoint of flexibility. Both peroxide-based crosslinkers and bifunctional isocyanate-based crosslinkers form flexible two-dimensional crosslinks, whereas trifunctional isocyanate-based crosslinkers form stronger three-dimensional crosslinks. At the time of bending, two-dimensional cross-linking, which is a more flexible cross-linking, is advantageous. However, since the durability is poor and the peeling is likely to occur only by the two-dimensional cross-linking, the hybrid cross-linking of the two-dimensional cross-linking and the three-dimensional cross-linking is good. It is a preferable embodiment to use or a bifunctional isocyanate-based cross-linking agent in combination.

The amount of the cross-linking agent used is, for example, preferably 0.01 to 10 parts by weight, more preferably 0.03 to 2 parts by weight, based on 100 parts by weight of the (meth) acrylic polymer. If it is within the above range, the bending resistance is excellent and it is a preferable embodiment.
<Other additives>
Further, the pressure-sensitive adhesive composition constituting the first pressure-sensitive adhesive layer may contain other known additives, for example, various silane coupling agents, polyether compounds of polyalkylene glycol such as polypropylene glycol, and coloring. Agents, powders such as pigments, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, antioxidants, light stabilizers, UV absorbers, polymerization prohibited Agents, antistatic agents (alkali metal salts and ionic liquids which are ionic compounds, etc.), inorganic or organic fillers, metal powders, particles, foils, etc. can be appropriately added depending on the intended use. .. Further, a redox system to which a reducing agent is added may be adopted within a controllable range.

[Other adhesive layers]
The second adhesive layer used in the display device of the present invention has a laminated structure laminated on the other surface of the optical film member.

In the third adhesive layer used in the display device of the present invention, the touch sensor member can be laminated on the surface of the thin film sealing layer opposite to the panel member.

The second pressure-sensitive adhesive layer, the third pressure-sensitive adhesive layer, and the other pressure-sensitive adhesive layer may have the same composition (same pressure-sensitive adhesive composition), the same characteristics, or different characteristics. , There are no particular restrictions.

<Formation of adhesive layer>
The plurality of pressure-sensitive adhesive layers in the present invention are preferably formed from the pressure-sensitive adhesive composition. Examples of the method for forming the pressure-sensitive adhesive layer include a method in which the pressure-sensitive adhesive composition is applied to a separator or the like that has been peeled off, and the polymerization solvent or the like is dried and removed to form the pressure-sensitive adhesive layer. Further, it can also be produced by a method of applying the pressure-sensitive adhesive composition to a polarizing film or the like and drying and removing a polymerization solvent or the like to form a pressure-sensitive adhesive layer on the polarizing film or the like. When applying the pressure-sensitive adhesive composition, one or more solvents other than the polymerization solvent may be newly added as appropriate.

As the peeling-treated separator, a silicone peeling liner is preferably used. When the pressure-sensitive adhesive composition of the present invention is applied onto such a liner and dried to form a pressure-sensitive adhesive layer, an appropriate method can be appropriately adopted as a method for drying the pressure-sensitive adhesive. Preferably, a method of heating and drying the coating film is used. The heating and drying temperature is, for example, preferably 40 to 200 ° C., more preferably 50 to 180 ° C., and particularly preferably 70 to 70 to 40 ° C. when preparing an acrylic pressure-sensitive adhesive using a (meth) acrylic polymer. It is 170 ° C. By setting the heating temperature in the above range, a pressure-sensitive adhesive having excellent pressure-sensitive properties can be obtained.

As the drying time, an appropriate time may be adopted as appropriate. The drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 when preparing an acrylic pressure-sensitive adhesive using a (meth) acrylic polymer, for example. Minutes.

Various methods are used as the method for applying the pressure-sensitive adhesive composition. Specifically, for example, roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Examples include the extrusion coating method.

The thickness of the adhesive layer used in the display device of the present invention is preferably 1 to 200 μm, more preferably 5 to 150 μm, and further preferably 10 to 100 μm. The adhesive layer may be a single layer or may have a laminated structure. Within the above range, it is a preferable embodiment without hindering bending and in terms of adhesion (retention resistance). Further, when a plurality of adhesive layers are provided, it is preferable that all the adhesive layers are within the above range.
The upper limit of the glass transition temperature (Tg) of the adhesive layer used in the laminated body for the flexible image display device of the present invention is preferably 0 ° C. or lower, more preferably −20 ° C. or lower, still more preferably −25 ° C. It is as follows. When the Tg of the adhesive layer is within such a range, the adhesive layer is less likely to become hard even in a high speed region at the time of bending, has excellent stress relaxation property, and can realize a flexible image display device that can be bent or folded.

[Panel member]
The panel member may include an image display panel and a panel base such as a substrate that holds the image display panel. A sealing member (thin film sealing layer, etc.) is arranged on the visual side of the image display panel. The substrate may be one that holds the image display panel and has appropriate strength and flexibility. As such a substrate, a resin sheet or the like is used. The material of the resin sheet is not particularly limited and can be appropriately selected according to the type of the panel.

As the image display panel, a known one is used. Examples of the image display panel include an organic electroluminescence (EL) panel. The image display panel is not limited to the organic EL panel, and may be a liquid crystal panel, an electrophoresis type display panel (electronic paper), or the like. For example, a bendable liquid crystal panel can be formed by using a flexible substrate such as a resin substrate as a transparent substrate that sandwiches the liquid crystal layer.

<Thin film sealing layer>
The thin film encapsulation (TFEE) has a function of preventing the image display panel from being exposed to moisture and / or air. The thin film sealing layer is formed of an inorganic / organic multilayer film in which a passivation film and a resin film are alternately laminated on a light emitting layer. Examples of the constituent material of the thin film encapsulating layer include materials having low water permeability, for example, inorganic materials such as silicon nitride, silicon oxynitride, carbon oxide, carbon nitride, and aluminum oxide, and resins.

[Touch sensor member]
As the touch sensor, for example, a touch sensor used in the field of an image display device or the like is used. Examples of the touch sensor include, but are not limited to, a resistance film type, a capacitance type, an optical type, or an ultrasonic type.

Capacitive touch sensors usually include a transparent conductive layer. Examples of such a touch sensor include a laminate of a transparent conductive layer and a transparent base material. Examples of the transparent substrate include a transparent film.

<Transparent conductive layer>
The transparent conductive layer is not particularly limited, but a conductive metal oxide, metal nanowires, or the like is used. Examples of the metal oxide include indium oxide (ITO: Indium Tin Oxide) containing tin oxide and tin oxide containing antimony. The transparent conductive layer may be a conductive pattern composed of a metal oxide or a metal. Examples of the shape of the conductive pattern include, but are not limited to, a striped shape, a square shape, and a grid shape.

<Transparent film>
As the transparent film, for example, a transparent resin film is used. The resins constituting the transparent film include polyester resin (including polyarylate resin), acetate resin, polyether sulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, and acrylic resin. Resin, polyvinyl chloride resin, vinylidene chloride resin, polystyrene resin, polyvinyl alcohol resin, sulfide resin (for example, polyphenylene sulfide resin), polyether ether ketone resin, cellulose resin, epoxy resin, Examples include urethane-based resins. The transparent film may contain one kind of these resins, or may contain two or more kinds of these resins. Of these resins, polyester-based resins, polyimide-based resins and polyether sulfone-based resins are preferable. However, the resins constituting the transparent film are not limited to these resins.

[Protective member]
The protective member is laminated on the surface side of the panel member opposite to the second adhesive layer via the fourth adhesive layer. The protective member serves as a reinforcing plate that is attached to the back surface of the flexible image display panel to reinforce the mechanical strength, and is a resin base material for protecting the flexible image display panel from scratches and impacts, and is formed in the form of a film. Has been done.

[Laminated structure]
The laminated structure of the present invention has a panel member. Further, in the display device, the laminated structure has a layer on the surface on the side of the second adhesive layer, which will be described later, which is more easily broken than the window member and the optical film member when bent and deformed.

[Display device]
The display device of the present invention includes an optical film member, a first adhesive layer, a window member laminated on one surface of the optical film member via the first adhesive layer, a second adhesive layer, and the other of the optical film members. It has a laminated structure laminated on the surface of the surface via a second adhesive layer, and is configured to be bendable.

FIG. 2 is a cross-sectional view showing one embodiment of the display device according to the present invention. The display device 100 includes an optical film member 110, a first adhesive layer 120, a window member 130 laminated on one surface of the optical film member 110 via the first adhesive layer 120, a second adhesive layer 140, and the like. The laminated structure 101 laminated on the other surface of the optical film member 110 via the second adhesive layer 140 is included. The laminated structure 101 includes a panel member 150. The display device 100 is configured to be foldable.

Optionally, the window member 130 may have a hardcourt layer 131 on a surface opposite to the first adhesive layer 120.

Although optional, the optical film member 110 can be a circularly polarizing functional film laminate 115 in which a retardation film 113 is laminated on a polarizing film 111. The circularly polarized light function film laminate 115, for example, generates circularly polarized light or adjusts the viewing angle in order to prevent light incident on the inside of the polarizing film 111 from the visible side from being internally reflected and emitted to the visible side. It is for compensation.

Although optional, the polarizing film 111 can be a laminate in which the polarizing element protective film 119 is laminated on at least one surface of the polarizing element 117 and the polarizing element 117.

Although optional, the polarizing element protective film 111 may contain an acrylic resin.

The laminated structure 101 has a layer on the surface on the side of the second adhesive layer 140 that is more easily broken than the window member 130 and the optical film member 110 when bent and deformed.

Although optional, the laminated structure 101 further has a third adhesive layer 160, forms a thin film sealing layer 151 on the surface of the panel member 150 on the second adhesive layer 140 side, and is a panel of the thin film sealing layer 151. The touch sensor member 170 is laminated on the surface opposite to the member 150 via the third adhesive layer 160, and the transparent conductive layer 171 is formed on the surface opposite to the panel member 150 of the touch sensor member 170. The layer 171 can be laminated on the second adhesive layer 140 as a layer that is more easily broken than the window member 130 and the optical film member 110.

Although optional, a fourth adhesive layer 180 may be further provided on the surface of the panel member 150 opposite to the third adhesive layer 160, and the protective member 190 may be laminated via the fourth adhesive layer 180.

In the display device 100, when the display device 100 is bent at an angle of 180 ° with the window member 130 on the outside and the display device 100 is bent at an angle of 180 °, the distance between the outermost surfaces of the display device 100 facing each other in parallel is large. When the optical film member 110 is bent and deformed to 4 mm, the strain in the direction parallel to the bending radial direction generated on one surface of the optical film member 110 and the bending radial direction generated on the surface of the window member 130 facing the first adhesive layer 120. The optical film member 110 and the window member 130 are each single layer so that the difference from the strain in the direction orthogonal to A is the same as when the display device is bent and deformed so that the outside and the inside when the display device is bent and deformed are the same. In the state of, when bent at an angle of 180 ° and bent at an angle of 180 °, the optical film member 110 and the window member 130 are bent and deformed so that the distance between the outermost surfaces facing each other in parallel is 4 mm. The difference between the strain in the direction orthogonal to the bending radial direction generated on the outer surface of the optical film member 110 and the strain in the direction parallel to the bending radial direction generated on the inner surface of the window member 130. A', the display device 100 is bent at an angle of 180 ° with the window member 130 on the outside, and the distance between the outermost surfaces of the display device 100 facing each other in parallel is 4 mm in a state of being bent at an angle of 180 °. When bent and deformed so as to be, the strain in the direction orthogonal to the bending radial direction generated on the other surface of the optical film 110 and the bending radial direction generated on the surface of the laminated structure 101 facing the second adhesive layer 140 The optical film member 110 and the laminated structure 101 are each made of a single layer so that the difference from the strain in the direction of bending is B, and the outside and the inside when the display device is bent and deformed are the same as when the display device is bent and deformed. In the state of being bent at an angle of 180 ° and bent at an angle of 180 °, the optical film member 110 and the laminated structure 101 are bent and deformed so that the distance between the outermost surfaces facing each other in parallel is 4 mm. The difference between the strain in the direction orthogonal to the bending radial direction generated on the inner surface of the optical film member 110 and the strain in the direction parallel to the bending radial direction generated on the outer surface of the laminated structure 101. When is B', bending deformation is performed by allowing the following equations (1), (2) and (3) to hold between the strain differences A, A', B and B'. The elongation of the fragile layer at the time of It is suppressed to a value smaller than the elongation at break.
0.3 <A / A'<1.2 ... (1)
B / B'<1.7A / A'-0.15 ... (2)
0 <B / B'<1.25 ... (3)

A is orthogonal to the bending radial direction generated on the outer surface of the optical film member 110 when the first adhesive layer 120 is bent between the optical film member 110 and the window member 130 to cause bending deformation. It is the difference between the strain in the direction of bending and the strain in the direction orthogonal to the bending radial direction generated on the inner surface of the window member 130, and A'bends the optical film member 110 and the window member 130 in a single layer state, respectively. The strain in the direction orthogonal to the bending radial direction generated on the outer surface of the optical film member 110 and the strain in the direction orthogonal to the bending radial direction generated on the inner surface of the window member 130 when the bending deformation is caused. Since the difference between A and A'is A', the harder the first adhesive layer 120, the smaller the value of A / A', that is, the hardness of the first adhesive layer 120 in the configuration of the display device 100. It is considered to be an index. Similarly, B / B'is considered to be an index regarding the hardness of the second adhesive layer 140 in the configuration of the display device 100, that is, the harder the second adhesive layer 140 is, the smaller the value of B / B'is.

In this regard, in a laminated body in which a plurality of layers and / or members are laminated via a plurality of adhesive layers, the bending displacement that occurs on the surfaces of the respective layers and / or the members facing each other via the respective adhesive layers is the respective adhesive layers. When the laminate is bent and deformed by appropriately selecting the hardness of the plurality of adhesive layers, paying attention to the fact that they influence each other through the above and affect the elongation generated in each layer and / or the member. In addition, the present inventors can suppress the elongation of the layer and / or the member vulnerable to bending contained in the laminated body, and suppress the breakage of the layer and / or the member vulnerable to bending. Found for the first time. Therefore, the hardness of each of the first adhesive layer 120 and the second adhesive layer 140 is determined by the formula (A / A', B / B', which defines the conditions for A / A'and B / B', using A / A'and B / B'. By appropriately selecting to satisfy 1) to (3), the elongation of the easily broken layer when bent and deformed is suppressed to a value smaller than the fracture elongation, and the easily broken layer is suppressed from breaking. can do.

Here, as a factor that determines the hardness of the adhesive layer, the shear modulus G'of the adhesive layer is the dominant factor, but the thickness of the adhesive layer is also a factor. The smaller the thickness of the adhesive layer, the harder the adhesive layer.

Although optional, the shear modulus G'of the second adhesive layer 140 can be larger than the shear modulus G'of the first adhesive layer 110. In this regard, in a laminated body in which a plurality of layers and / or members are laminated via a plurality of adhesive layers, when a certain adhesive layer is hardened, a layer laminated on the outside of the adhesive layer at the time of bending of the laminated body or The present inventors have found for the first time that the strain of the member shifts to the tension side, and the strain of the layer and the member laminated inside the adhesive layer shifts to the compression side. Since the shear modulus G'of the adhesive layer is the dominant factor of the hardness of the adhesive layer, such a configuration allows the fragile layer laminated inside the second adhesive layer 140. The tensile strain generated in a transparent conductive layer 171 or a thin film sealing layer 151 can be made smaller.

Although optional, the shear modulus G'of the fourth adhesive layer 180 is smaller than the shear modulus G'of the second adhesive layer 140 and smaller than the shear modulus G'of the third adhesive layer 160. can do. When the adhesive layer is softened, the strain of the layer or member laminated on the outside of the adhesive layer shifts to the compression side, and the strain of the layer or member laminated on the inside of the adhesive layer shifts to the tension side. Since the shear modulus G'of the adhesive layer is the dominant factor of the hardness of the adhesive layer, such a configuration allows the fragile layer laminated on the outside of the fourth adhesive layer 180. The tensile strain generated in a transparent conductive layer 171 or a thin film sealing layer 151 can be made smaller.

Although optional, the relationship of 0.8 <A / A'can be further established between the strain differences A and A'. When the adhesive layer is softened, the strain of the layer or member laminated on the outside of the adhesive layer shifts to the compression side, and the strain of the layer or member laminated on the inside of the adhesive layer shifts to the tension side. It is considered that the harder the first adhesive layer 120 is, the smaller the value of A / A'is. Therefore, with such a configuration, the hard coat layer which is a layer laminated on the outside of the first adhesive layer 120 is considered. The tensile strain generated in 131 can be made smaller.

As described above, in a laminate in which a plurality of layers and / or members are laminated via a plurality of adhesive layers, when a certain adhesive layer is hardened, it is laminated on the outside of the adhesive layer when the laminate is bent. The strain of the layer or member shifts to the tension side, and the strain of the layer or member laminated inside the adhesive layer shifts to the compression side. Therefore, when it is desired to suppress the breakage of a layer that is vulnerable to bending inside a certain adhesive layer, the hardness of the adhesive layer is changed to a larger one, and the layer that is vulnerable to bending outside a certain adhesive layer. If it is desired to suppress the breakage of the adhesive layer, the hardness of the adhesive layer may be changed to a smaller one.

For example, in the process of designing a display device, if the fragile layer of the laminated structure inside the first adhesive layer or the second adhesive layer is broken or predicted to be broken, the first adhesive layer or the first adhesive layer is used. (Ii) By changing the hardness of at least one of the adhesive layers to a larger one, it is possible to suppress the breakage of the easily broken layer. At this time, factors that determine the hardness of the adhesive layer include, for example, the shear elastic modulus G'of the adhesive layer and the thickness of the adhesive layer. Breaking of the fragile layer can be suppressed by changing to a smaller one or changing the elastic modulus of at least one of the first adhesive layer or the second adhesive layer to a higher one.

Further, at this time, since the fragile layer of the laminated structure is outside the third adhesive layer and the fourth adhesive layer, the hardness of at least one of the third adhesive layer or the fourth adhesive layer is changed to a smaller one. By, for example, changing the thickness of the third adhesive layer to a larger one and / or changing the shear elasticity G'of at least one of the third adhesive layer or the fourth adhesive layer to a lower one. , It is possible to suppress the breakage of the easily broken layer.

The display device shown in FIG. 3 is basically the same as that shown in FIG. 2, but the layer that is more easily broken than the window member 130 and the optical film member 110 is the second adhesive layer in the display device of FIG. In contrast to the transparent conductive layer 171 formed on the surface of the touch sensor member 170 laminated between the 140 and the panel member 150 on the surface opposite to the panel member 150, in the display device of FIG. 4, the panel member 150 The difference is that the thin film sealing layer 151 is formed on the surface of the second adhesive layer 140 side.

[Base material laminate]
In the base material laminate 103 of the present invention, a layer that is more easily broken than the window member and the optical film member is formed on the surface opposite to the touch sensor member panel member laminated between the second adhesive layer panel members. It is used for a display device that is a transparent conductive layer, and is used on one surface of an optical film member, the window member laminated on one surface of the optical film member via the first adhesive layer, and the other surface of the optical film member. It has a touch sensor member including a transparent conductive layer laminated via the second adhesive layer.

The display device and the base material laminate of the present invention will be further described with reference to the following examples. The display device and the base material laminate of the present invention are not limited to these examples.
[Example 1]

[Polarizer]
An amorphous polyethylene terephthalate (hereinafter, also referred to as “PET”) (IPA copolymerized PET) film (thickness: 100 μm) having 7 mol% of isophthalic acid unit was prepared as a thermoplastic resin base material, and the surface was treated with corona (thickness: 100 μm). 58 W / m2 / min) was applied. On the other hand, acetacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Gosefimer Z200 (average degree of polymerization: 1200, saponification degree: 98.5 mol%, acetacetylation degree: 5 mol%) Prepare PVA (polymerization degree 4200, saponification degree 99.2%) added in an amount of 1% by weight, prepare a coating solution of a PVA aqueous solution having a PVA-based resin of 5.5% by weight, and measure the thickness after drying. Was coated to 12 μm and dried in an atmosphere of 60 ° C. for 10 minutes by hot air drying to prepare a laminate having a layer of PVA-based resin on the substrate.

Next, this laminated body was first stretched 1.8 times at a free end at 130 ° C. in the air (aerial auxiliary stretching) to produce a stretched laminated body. Next, a step of insolubilizing the PVA layer in which the PVA molecules contained in the stretched laminate were oriented was performed by immersing the stretched laminate in a boric acid insoluble aqueous solution having a liquid temperature of 30 ° C. for 30 seconds. The boric acid insolubilized aqueous solution in this step had a boric acid content of 3 parts by weight with respect to 100 parts by weight of water. A colored laminate was produced by dyeing this stretched laminate. In the colored laminate, the stretched laminate is mixed with a dyeing solution containing iodine and potassium iodide at a liquid temperature of 30 ° C., so that the single transmittance of the PVA layer constituting the polarizing element finally produced is 40 to 44%. The PVA layer contained in the stretched laminate was stained with iodine by immersing it in an arbitrary time. In this step, the dyeing solution used water as a solvent and had an iodine concentration in the range of 0.1 to 0.4% by weight and a potassium iodide concentration in the range of 0.7 to 2.8% by weight. The ratio of iodine to potassium iodide concentrations is 1: 7. Next, a step of cross-linking the PVA molecules of the PVA layer on which iodine was adsorbed was performed by immersing the colored laminate in a boric acid cross-linked aqueous solution at 30 ° C. for 60 seconds. The boric acid crosslinked aqueous solution in this step had a boric acid content of 3 parts by weight with respect to 100 parts by weight of water and a potassium iodide content of 3 parts by weight with respect to 100 parts by weight of water.

Further, the obtained colored laminate was stretched 3.05 times in the same direction as the previous stretching in air (boric acid water stretching) at a stretching temperature of 70 ° C. in a boric acid aqueous solution, and finally. An optical film laminate having a draw ratio of 5.50 times was obtained. The optical film laminate was taken out from the boric acid aqueous solution, and the boric acid adhering to the surface of the PVA layer was washed with an aqueous solution having a potassium iodide content of 4 parts by weight based on 100 parts by weight of water. The washed optical film laminate was dried by a drying step with warm air at 60 ° C. The thickness of the polarizing element contained in the obtained optical film laminate was 5 μm.

[Polarizer protective film]
As the polarizing element protective film, a methacrylic resin pellet having a glutarimide ring unit was extruded, formed into a film, and then stretched. This polarizing element protective film was an acrylic film having a thickness of 40 μm and a moisture permeability of 160 g / m ^2.

[Polarizing film]
Next, the polarizing element and the polarizing element protective film were bonded together using the adhesive shown below to obtain a polarizing film.

As the adhesive (active energy ray-curable adhesive), each component is mixed according to the formulation table shown in Table 1, stirred at 50 ° C. for 1 hour, and the adhesive (active energy ray-curable adhesive A). Was prepared. The numerical value in the table is the blending amount (addition amount), which indicates the solid content or the solid content ratio (weight basis), and indicates the weight% when the total amount of the composition is 100% by weight. The components used are as follows.
HEAA: Hydroxyethylacrylamide M-220: ARONIX M-220, Tripropylene glycol diacrylate), ACMO: Acryloylmorpholin AAEM: 2-acetoacetoxyethyl methacrylate, UP-1190: ARUFON UP- 1190, Toagosei IRG907: IRGACURE907, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropane-1-one, BASF DETX-S: KAYACURE DETX-S, diethylthioxanthone, Nippon Kayaku Made by Yakusha

In the examples and comparative examples using the adhesive, the polarizing element protective film and the polarizing element are laminated via the adhesive, and then irradiated with ultraviolet rays to cure the adhesive and bond the adhesive. An agent layer was formed. For UV irradiation, gallium-filled metal halide lamp (Fusion UV Systems, Inc., trade name "Light HAMMER10", bulb: V bulb, peak illuminance: 1600 mW / cm ² , integrated irradiation dose 1000 / mJ / cm ² (wavelength) 380-440 nm))) was used.

[Phase difference film]
The retardation film (1/4 wavelength retardation plate) of this embodiment is composed of two layers, a retardation layer for a 1/4 wavelength plate and a retardation layer for a 1/2 wavelength plate in which a liquid crystal material is oriented and immobilized. It was a composed retardation film. Specifically, it was manufactured as follows.

(Liquid crystal material)
As a material for forming the retardation layer for 1/2 wave plate and the retardation layer for 1/4 wave plate, a polymerizable liquid crystal material showing a nematic liquid crystal phase (manufactured by BASF, trade name: Paliocolor LC242) was used. A photopolymerization initiator (manufactured by BASF, trade name: Irgacure 907) for the polymerizable liquid crystal material was dissolved in toluene. Further, for the purpose of improving the coatability, a megafuck series made by DIC was added in an amount of about 0.1 to 0.5% depending on the thickness of the liquid crystal to prepare a liquid crystal coating liquid. The liquid crystal coating liquid was applied onto the oriented substrate with a bar coater, dried by heating at 90 ° C. for 2 minutes, and then oriented and fixed by ultraviolet curing in a nitrogen atmosphere. As the base material, for example, PET, which can transfer the liquid crystal coating layer later, was used. Further, for the purpose of improving coatability, about 0.1% to 0.5% of a fluoropolymer, which is a Megafuck series made by DIC, is added depending on the thickness of the liquid crystal layer, and MIBK (methyl isobutyl ketone), cyclohexanone, or MIBK is added. A coating solution was prepared by dissolving the mixture in a solid content concentration of 25% using a mixed solvent of cyclohexanone and cyclohexanone. This coating liquid was applied to a base material with a wire bar to obtain a drying step of 3 minutes at a setting of 65 ° C., and the orientation was fixed by ultraviolet curing in a nitrogen atmosphere. As the base material, for example, PET, which can transfer the liquid crystal coating layer later, was used.

(Manufacturing process)
The manufacturing process of this embodiment will be described with reference to FIG. In this manufacturing step 20, the base material 14 is provided by a roll, and the base material 14 is supplied from the supply reel 21. In the manufacturing process 20, the coating liquid of the ultraviolet curable resin 10 was applied to the base material 14 by the die 22. In this manufacturing step 20, the roll plate 30 was a cylindrical mold for forming a concave-convex shape related to the alignment film for the 1/4 wave plate of the 1/4 wave plate on the peripheral side surface. In the manufacturing step 20, the base material 14 coated with the ultraviolet curable resin is pressed against the peripheral side surface of the roll plate 30 by the pressure roller 24, and the ultraviolet curable resin is produced by irradiation with ultraviolet rays by the ultraviolet irradiation device 25 composed of a high-pressure mercury lamp. It was cured. As a result, in the manufacturing process 20, the uneven shape formed on the peripheral side surface of the roll plate 30 was transferred to the base material 14 so as to be 75 ° with respect to the MD direction. Then, the base material 14 was peeled from the roll plate 30 integrally with the ultraviolet curable resin 10 cured by the peeling roller 26, and the liquid crystal material was applied by the die 29. After that, the liquid crystal material was cured by irradiation with ultraviolet rays by the ultraviolet irradiation device 27, and a configuration related to the retardation layer for a quarter wave plate was created by these.

Subsequently, in this step 20, the base material 14 is conveyed to the die 32 by the transfer roller 31, and the coating liquid of the ultraviolet curable resin 12 is applied onto the retardation layer for the 1/4 wave plate of the base material 14 by the die 32. bottom. In this manufacturing step 20, the roll plate 40 was a cylindrical mold for forming a concave-convex shape related to the alignment film for the 1/2 wave plate of the 1/4 wavelength retardation plate on the peripheral side surface. In the manufacturing process 20, the base material 14 coated with the ultraviolet curable resin is pressed against the peripheral side surface of the roll plate 40 by the pressure roller 34, and the ultraviolet curable resin is produced by irradiation with ultraviolet rays by the ultraviolet irradiation device 35 composed of a high-pressure mercury lamp. It was cured. As a result, in the manufacturing step 20, the uneven shape formed on the peripheral side surface of the roll plate 40 was transferred to the base material 14 so as to be 15 ° with respect to the MD direction. Then, the base material 14 was peeled from the roll plate 40 integrally with the ultraviolet curable resin 12 cured by the peeling roller 36, and the liquid crystal material was applied by the die 39. After that, the liquid crystal material is cured by irradiation with ultraviolet rays by the ultraviolet irradiation device 37, thereby creating a configuration related to the retardation layer for 1/2 wave plate, and the retardation layer for 1/4 wave plate and 1/2 wavelength. A phase difference film having a thickness of 7 μm composed of two layers of a wave plate retardation layer was obtained.

[Optical film member (circularly polarized light functional film laminate)]
The retardation film and the polarizing film obtained as described above are continuously bonded to each other by a roll-to-roll method using the above adhesive so that the axis angle between the slow phase axis and the absorption axis is 45 °. , A laminated film (circularly polarized light functional film laminated body) was produced.

[First adhesive layer]
The adhesive layer constituting the first adhesive layer of this example was produced by the following method.
<Preparation of acrylic oligomer>
<Oligomer A>
60 parts by weight of dicyclopentanyl methacrylate (DCPMA) and 40 parts by weight of methyl methacrylate (MMA) as a monomer component, 3.5 parts by weight of α-thioglycerol as a chain transfer agent, and 100 parts by weight of toluene as a polymerization solvent are mixed. Then, the mixture was stirred at 70 ° C. for 1 hour under a nitrogen atmosphere. Next, 0.2 parts by weight of 2,2'-azobisisobutyronitrile (AIBN) was added as a thermal polymerization initiator, and the mixture was reacted at 70 ° C. for 2 hours and then heated to 80 ° C. for 2 hours. It was reacted. Then, the reaction solution was heated to 130 ° C., and toluene, the chain transfer agent and the unreacted monomer were dried and removed to obtain a solid acrylic oligomer (oligomer A). The weight average molecular weight of the oligomer A was 5100, and the glass transition temperature (Tg) was 130 ° C.
<Oligomer B>
A solid acrylic oligomer (oligomer B) was obtained in the same manner as in the preparation of oligomer A, except that the monomer component was changed to 60 parts by weight of dicyclohexyl methacrylate (CHMA) and 40 parts by weight of butyl methacrylate (BMA). The weight average molecular weight of the oligomer B was 5000, and the glass transition temperature (Tg) was 44 ° C.

(Polymerization of prepolymer)
43 parts by weight of lauryl acrylate (LA), 44 parts by weight of 2-ethylhexyl acrylate (2EHA), 6 parts by weight of 4-hydroxybutyl acrylate (4HBA), and N-vinyl-2-pyrrolidone (NVP) as monomer components for prepolymer formation. ) 7 parts by weight and 0.015 parts by weight of BASF's "Irgacure 184" as a photopolymerization initiator were blended and polymerized by irradiating with ultraviolet rays to obtain a prepolymer composition (polymerization rate; about 10%). ..

(Preparation of adhesive composition)
To 100 parts by weight of the above prepolymer composition, 0.07 parts by weight of 1,6-hexanediol diacrylate (HDDA), 1 part by weight of the above oligomer A, and a silane coupling agent (Shin-Etsu Chemical) as post-addition components. Manufactured by "KBM403"): After adding 0.3 parts by weight, these were uniformly mixed to prepare a pressure-sensitive adhesive composition. Hereinafter, this pressure-sensitive adhesive composition is also referred to as a pressure-sensitive adhesive composition 1.

(Making an adhesive sheet)
A 75 μm-thick polyethylene terephthalate (PET) film (“Diafoil MRF75” manufactured by Mitsubishi Chemical Co., Ltd.) with a silicone-based release layer on the surface is used as a base material (cum-heavy release film), and the above-mentioned photocurable adhesive is applied on the base material. The agent composition was applied so as to have a thickness of 50 μm to form a coating layer. A PET film ("Diafoil MRE75" manufactured by Mitsubishi Chemical Corporation) having a thickness of 75 μm, one side of which was treated with silicone peeling, was bonded onto this coating layer as a cover sheet (also a light peeling film). The laminated body is photo-cured by irradiating it with ultraviolet rays from the cover sheet side with a black light whose position is adjusted so that the irradiation intensity on the irradiation surface directly under the lamp is 5 mW / cm ^2, and a pressure-sensitive adhesive sheet having a thickness of 50 μm is formed. Obtained. Hereinafter, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive composition 1 produced by the same method is also referred to as the pressure-sensitive adhesive layer 1.

[Second adhesive layer]
An adhesive layer constituting the second adhesive layer of this example was prepared under the same conditions as the first adhesive layer except that the thickness was 15 μm.

[Third adhesive layer]
The adhesive layer constituting the third adhesive layer of this example was produced by the following method.
<Preparation of (meth) acrylic polymer A1>
A four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler was charged with a monomer mixture containing 99 parts by weight of butyl acrylate (BA) and 1 part by weight of 4-hydroxybutyl acrylate (HBA). ..

Further, with respect to 100 parts by weight of the monomer mixture (solid content), 0.1 part by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator is charged together with ethyl acetate, and nitrogen gas is gently stirred. Was introduced and replaced with nitrogen, and then the polymerization reaction was carried out for 7 hours while keeping the liquid temperature in the flask at around 55 ° C. Then, ethyl acetate was added to the obtained reaction solution to prepare a solution of (meth) acrylic polymer A1 having a weight average molecular weight of 1.6 million, which was adjusted to a solid content concentration of 30%.

<Preparation of acrylic pressure-sensitive adhesive composition>
0.1 weight by weight of an isocyanate-based cross-linking agent (trade name: Takenate D110N, trimethylolpropane xylylene diisocyanate, manufactured by Mitsui Chemicals, Inc.) with respect to 100 parts by weight of the solid content of the obtained (meth) acrylic polymer A1 solution. , 0.3 parts by weight of benzoyl peroxide (trade name: Niper BMT, manufactured by Nippon Oil & Fats Co., Ltd.), which is a peroxide-based cross-linking agent, and silane coupling agent (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.). ) 0.08 parts by weight was blended to prepare an acrylic pressure-sensitive adhesive composition. Hereinafter, this pressure-sensitive adhesive composition is also referred to as a pressure-sensitive adhesive composition 2.

<Making an adhesive sheet>
The acrylic pressure-sensitive adhesive composition is uniformly coated on the surface of a 38 μm-thick polyethylene terephthalate film (PET film, transparent substrate, separator) treated with a silicone-based release agent with a fountain coater at 155 ° C. The film was dried in an air circulation type constant temperature oven for 2 minutes to form an adhesive layer (third adhesive layer) having a thickness of 20 μm on the surface of the substrate. A polyethylene terephthalate film (PET film, transparent base material, separator) having a thickness of 38 μm, one side of which was treated with silicone peeling, was bonded onto this coating layer as a cover sheet (also a light peeling film). Hereinafter, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive composition 2 produced by the same method is also referred to as the pressure-sensitive adhesive layer 2.

[Fourth adhesive layer]
An adhesive layer constituting the fourth adhesive layer of this example was produced under the same conditions as the first adhesive layer except that the thickness was 25 μm.

[Window member]
As the window member, an acrylic hard coat layer on one side of a transparent polyimide film as a window film (manufactured by KOLON, product name "C_50", thickness 50 μm (hereinafter, this window film is also referred to as “window film 1”)). The one provided with (thickness 10 μm) was used.

The hardcoat layer was formed using a coating agent for the hardcoat layer. More specifically, first, a coating agent was applied to one side of the transparent polyimide film to form a coating layer, and the coating layer was heated together with the transparent polyimide film at 90 ° C. for 2 minutes. Next, a hard coat layer was formed by irradiating the coated layer with ultraviolet rays using a high-pressure mercury lamp at an integrated light amount of 300 mJ / cm ^2. The window member was manufactured in this way.

The coating agent for the hard coat layer is 100 parts by mass of a polyfunctional acrylate (manufactured by Aika Kogyo Co., Ltd., product name "Z-850-16") as a base resin, and a leveling agent (manufactured by DIC Corporation, product name: GRANDIC PC). -4100) Mix 5 parts by mass and 3 parts by mass of the photopolymerization initiator (manufactured by Ciba Japan, trade name: Irgacure 907) and dilute with methylisobutylketone so that the solid content concentration becomes 50% by mass. Prepared by

[Touch sensor member]
As a transparent resin base material, a cycloolefin-based resin base material (“ZEONOR” manufactured by Nippon Zeon Co., Ltd., thickness 25 μm, in-plane birefringence 0.0001) was prepared.

Next, a diluted solution of the hard coat composition composed of the binder resin is applied to the upper surface of the transparent resin base material, and the diluted solution of the hard coat composition containing the binder resin and a plurality of particles is applied to the lower surface of the transparent resin base material. After coating and then drying these, both sides were irradiated with ultraviolet rays to cure the hardcourt composition. As a result, a first cured resin layer (thickness 1 μm) containing no particles was formed on the upper surface of the transparent resin base material, and a second cured resin layer (thickness 1 μm) containing particles was formed on the lower surface of the transparent resin base material.

As the particles, crosslinked acrylic / styrene resin particles (“SSX105” manufactured by Sekisui Jushi Co., Ltd., diameter 3 μm) were used. Urethane-based polyfunctional polyacrylate (“UNIDIC” manufactured by DIC Corporation) was used as the binder resin.

Next, a diluted solution of an optical adjustment composition containing zirconia particles and an ultraviolet curable resin (“Opstar Z7412” manufactured by JSR Corporation, refractive index 1.62) was applied to the upper surface of the first cured resin layer, and the temperature was 80 ° C. After drying for 3 minutes in, it was irradiated with ultraviolet rays. As a result, an optical adjustment layer (thickness 0.1 μm) was formed on the upper surface of the first cured resin layer.

Next, an ITO layer (thickness 40 nm), which is an amorphous transparent conductive layer, was formed on the upper surface of the optical adjustment layer by sputtering.

As a result, an amorphous transparent conductive film including a second cured resin layer, a transparent resin base material, a first cured resin layer, an optical adjustment layer, and an amorphous transparent conductive layer was produced.

Next, the obtained amorphous transparent conductive film was heat-treated at 130 ° C. for 90 minutes to crystallize the ITO layer.

[Panel member]
As a panel base, a polyimide resin film (“UPILEX” manufactured by Ube Industries, Ltd., thickness 25 μm) made from BPDA (biphenyltetracarboxylic dianhydride) was prepared.

Next, an ITO layer (thickness 40 nm), which is an amorphous transparent conductive layer, was formed on the upper surface of the polyimide resin film by sputtering.

Next, the obtained amorphous transparent conductive film was heat-treated at 130 ° C. for 90 minutes to crystallize the ITO layer.

Then, the obtained ITO layer and the transparent conductive film with the ITO layer were used as a dummy for the thin film sealing layer and the panel member, respectively. Hereinafter, the dummy ITO layer of the thin film encapsulation layer is also referred to as "thin film encapsulation layer alternative ITO layer" or "alternative ITO layer".

[Protective member]
As the protective member of this example, a polyimide resin base material (“UPILEX” manufactured by Ube Industries, Ltd., thickness 50 μm) made from BPDA (biphenyltetracarboxylic dianhydride) was used.

Various evaluations were performed on each of the obtained members, layers, and films as follows. The characteristics of each of the obtained adhesive layers, hard coat layers, polarizing element protective films, ITO layers, and alternative ITO layers are shown in Tables 2-1 to 2-3.

[Example 2]
Each member, layer, film, and laminate were manufactured and produced under the same conditions as in Example 1 except that the pressure-sensitive adhesive composition 2 was used as the pressure-sensitive adhesive composition of the pressure-sensitive adhesive layer constituting the second pressure-sensitive adhesive layer. , Various evaluations were performed as follows. The characteristics of each of the obtained adhesive layers, hard coat layers, polarizing element protective films, ITO layers, and alternative ITO layers are shown in Tables 2-1 to 2-3.

[Example 3]
Each member, layer, film, and laminate were manufactured and manufactured under the same conditions as in Example 1 except that the following adhesive layer was used as the adhesive layer constituting the second adhesive layer, and various types were produced as follows. Evaluation was performed. The characteristics of each of the obtained adhesive layers, hard coat layers, polarizing element protective films, ITO layers, and alternative ITO layers are shown in Tables 2-1 to 2-3.

The adhesive layer constituting the second adhesive layer of this example was produced by the following method.
<Preparation of (meth) acrylic polymer A3>
Except that the polymerization reaction was carried out so that the mixing ratio (weight ratio) of ethyl acetate and toluene was 95/5 when the polymerization reaction was carried out for 7 hours while keeping the liquid temperature in the flask at around 55 ° C. Was carried out in the same manner as in the preparation of the (meth) acrylic polymer A1.
<Preparation of acrylic pressure-sensitive adhesive composition>
To 100 parts by weight of the solid content of the obtained (meth) acrylic polymer A1 solution, 0.15 parts by weight of trimethylolpropane / tolylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Coronate L) and a silane cup An acrylic pressure-sensitive adhesive composition was prepared by blending 0.08 parts by weight of a ring agent (trade name: KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.). Hereinafter, this pressure-sensitive adhesive composition is also referred to as a pressure-sensitive adhesive composition 3.

<Making an adhesive sheet>
The acrylic pressure-sensitive adhesive composition is uniformly coated on the surface of a 38 μm-thick polyethylene terephthalate film (PET film, transparent substrate, separator) treated with a silicone-based release agent with a fountain coater at 155 ° C. The film was dried in an air circulation type constant temperature oven for 2 minutes to form an adhesive layer (second adhesive layer) having a thickness of 15 μm on the surface of the substrate. Then, a polyethylene terephthalate film (PET film, transparent base material, separator) having a thickness of 38 μm, one side of which was treated with silicone peeling as a cover sheet (and a light peeling film), was bonded onto this coating layer. Hereinafter, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive composition 3 produced by the same method is also referred to as the pressure-sensitive adhesive layer 3.

[Example 4]
Each under the same conditions as in Example 1, except that the following adhesive layer was used as the adhesive layer constituting the second adhesive layer, and the display device and the base material laminate were produced as described below. Members, layers, films, and laminates were manufactured and manufactured, and various evaluations were performed as follows. The characteristics of each of the obtained adhesive layers, hard coat layers, polarizing element protective films, ITO layers, and alternative ITO layers are shown in Tables 2-1 to 2-3.

The adhesive layer constituting the second adhesive layer of this example was produced by the following method.

2-Ethylhexyl acrylate (2EHA) as a monomer component: 63 parts by weight, N-vinyl-2-pyrrolidone (NVP): 15 parts by weight, methyl methacrylate (MMA): 9 parts by weight, 2-hydroxyethyl acrylate ( HEA): 13 parts by weight, 2,2'-azobisisobutyronitrile as a polymerization initiator: 0.2 parts by weight, and 133 parts by weight of ethyl acetate as a polymerization solvent were put into a separable flask. The mixture was stirred for 1 hour while introducing nitrogen gas. After removing oxygen in the polymerization system in this manner, the temperature was raised to 65 ° C. and reacted for 10 hours, and then ethyl acetate was added to obtain an acrylic polymer solution having a solid content concentration of 30% by weight. The weight average molecular weight of the acrylic polymer in the above-mentioned acrylic polymer solution was 800,000.

Next, in the above acrylic polymer solution, an isocyanate-based cross-linking agent (trade name "Takenate D110N", manufactured by Mitsui Kagaku Co., Ltd.) was added to 100 parts by weight of the acrylic polymer (solid content) by 1.1 weight in terms of solid content. A pressure-sensitive adhesive composition was prepared by adding the portions in portions and mixing them. Hereinafter, this pressure-sensitive adhesive composition is also referred to as a pressure-sensitive adhesive composition 4.
<Making an adhesive sheet>
The pressure-sensitive adhesive composition 4 was uniformly coated on the surface of a 38 μm-thick polyethylene terephthalate film (PET film, transparent substrate, separator) treated with a silicone-based release agent with a fountain coater, and then a PET group was applied. The material having the coating layer formed on the material was put into an oven, and the coating layer was dried at 130 ° C. for 3 minutes to form an adhesive sheet having an adhesive layer having a thickness of 15 μm on one surface of the PET substrate. A polyethylene terephthalate film (PET film, transparent base material, separator) having a thickness of 38 μm, one side of which was treated with silicone peeling, was bonded onto this coating layer as a cover sheet (also a light peeling film).
Hereinafter, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive composition 4 produced by the same method is also referred to as the pressure-sensitive adhesive layer 4.

The display device and the base material laminate of this example were produced by the following methods.

The adhesive layer was transferred from the release film to one of the members holding each adhesive layer, and each member was laminated so as to sandwich the adhesive layer and crimped with a hand roller. A rectangular sample having a width of 30 mm and a length of 100 mm was cut from the obtained laminate to prepare an evaluation sample in which each member was laminated via an adhesive layer.

[Examples 5 to 7, 9, 10, 12, 13, 19, 22, 27, 28, Comparative Example 3]
The combinations of the types of the adhesive layers (adhesive layers 1 to 4) constituting the first adhesive layer, the second adhesive layer, the third adhesive layer, and the fourth adhesive layer were changed as shown in Tables 2-1 to 2-3. Except for this, each member, layer, film, and laminate were manufactured and manufactured under the same conditions as in Example 1, and various evaluations were performed as follows. The characteristics of each of the obtained adhesive layers, hard coat layers, polarizing element protective films, ITO layers, and alternative ITO layers are shown in Tables 2-1 to 2-3.

[Examples 21 and 23]
The combinations of the types of the adhesive layers (adhesive layers 1 to 4) constituting the first adhesive layer, the second adhesive layer, the third adhesive layer, and the fourth adhesive layer were changed as shown in Tables 2-1 to 2-3. Each member, layer, film, and laminate were manufactured and manufactured under the same conditions as in Example 1 except that the thickness of the first adhesive layer was 25 μm, and various evaluations were performed as follows. rice field. The characteristics of each of the obtained adhesive layers, hard coat layers, polarizing element protective films, ITO layers, and alternative ITO layers are shown in Tables 2-1 to 2-3.

[Examples 8, 11, 14, 15-18, 20, 24-26, Comparative Examples 1, 2, 4, 5]
The combinations of the types of the adhesive layers (adhesive layers 1 to 4) constituting the first adhesive layer, the second adhesive layer, the third adhesive layer, and the fourth adhesive layer were changed as shown in Tables 2-1 to 2-3. Except for this, each member, layer, film, laminate, display device, and substrate laminate were manufactured and manufactured under the same conditions as in Example 4, and various evaluations were performed as follows. The characteristics of each of the obtained adhesive layers, hard coat layers, polarizing element protective films, ITO layers, and alternative ITO layers are shown in Tables 2-1 to 2-3.

[Examples 29 to 31, Comparative Example 5]
The combinations of the types of the adhesive layers (adhesive layers 1 to 4) constituting the first adhesive layer, the second adhesive layer, the third adhesive layer, and the fourth adhesive layer were changed as shown in Tables 2-1 to 2-3. As a transparent polyimide film as a window film for window members, a product name "Capton (registered trademark) H type" (hereinafter, this window film is also referred to as "window film 2") manufactured by Toray DuPont Co., Ltd. was used. Except for this, each member, layer, film, and laminate were manufactured and manufactured under the same conditions as in Example 1, and various evaluations were performed as follows. The characteristics of each of the obtained adhesive layers, hard coat layers, polarizing element protective films, ITO layers, and alternative ITO layers are shown in Tables 2-1 to 2-3.

[evaluation]
(Measurement of thickness)
The thicknesses of the polarizing element, the polarizing element protective film, the retardation film, each adhesive layer, the transparent film, the window film, the protective member, and the like were measured using a dial gauge (manufactured by Mitutoyo). The thickness of the ITO layer and the alternative ITO layer was measured based on an image taken with a transmission electron microscope (TEM).
(Measurement of shear modulus G'of adhesive layer)
The separator was peeled off from the pressure-sensitive adhesive sheets of each Example and Comparative Example, and a plurality of pressure-sensitive adhesive sheets were laminated to prepare a test sample having a thickness of about 1.5 mm. This test sample is punched into a disk shape with a diameter of 7.9 mm, sandwiched between parallel plates, and dynamic viscoelasticity measurement is performed and measured under the following conditions using "Advanced Shear modulus Exhibition System (ARES)" manufactured by Shearometric Scientific. The shear modulus G'was read from the result.

(Measurement condition)
Deformation mode: Torsion measurement temperature: -40 ° C to 150 ° C
Temperature rise rate: 5 ° C / min Measurement frequency: 1Hz

(Measurement of strain and stress)
An optical film member, a laminate of a retardation film, a polarizing element, and a polarizing element protective film, a laminate of a stator and a polarizing element protective film, a transparent resin base material with an ITO layer, which is a touch sensor member, and a touch sensor member. A transparent resin base material, an alternative transparent resin base material with an alternative ITO layer corresponding to a panel member, an alternative transparent resin base material for a panel member, and a film for a protective member, and a obtained window film, a polarizing element, and a polarizing element protective film. , A sample having a width of 10 mm and a length of 100 mm was cut out from the adhesive layer 1, the adhesive layer 2, the adhesive layer 3, and the adhesive layer 4. Each of the obtained samples was installed in a tensile tester (product name "Autograph AG-IS" manufactured by Shimadzu Corporation), and the strain and stress when pulled at 200 mm / min were measured to obtain a strain-stress curve. .. The stress was converted into Pa units from the thickness and width. Further, each adhesive layer was obtained by laminating a plurality of adhesive layers to prepare an adhesive layer having a thickness of 100 μm.

When it is difficult to produce an adhesive layer having a thickness of 100 μm, a strain-stress curve can also be obtained by the following method.
1. 1. For a sample, the strain-stress curve is obtained in advance by the above method, and the curve is divided by the tensile modulus calculated from the slope of the curve in the range of 0.05% to 0.25% strain. This creates a standardized strain-stress curve.
2. 2. The shear modulus G'of the sample to be measured is measured and obtained by the above method.
3. 3. Measure the components of the sample to be measured and obtain the Poisson ratio ν.
4. E'= 2G'(1 + ν) for tensile modulus E'and shear modulus G'
Since the relational expression of 2. above holds. And 3. Calculate E'from G'and ν measured in.
5. Above 1. In the standardized strain-stress curve created in 4. above. By multiplying the tensile elastic modulus E'obtained in the above, the strain-stress curve of the sample to be measured can be obtained.

(Simulation of strain difference in the direction orthogonal to the bending radius direction)
Based on the obtained strain-stress curve of each member and film, the strain in the direction orthogonal to the bending radius direction of each member, layer and film when the bending deformation of each example and each comparative example is obtained by simulation. , A / A', B / B', 1.7A / A'-0.15 were calculated. The results are shown in Tables 2-1 to 2-3.

<Computer simulation software>
As the simulation software, Marc manufactured by MSC Software, which is nonlinear finite element analysis software, was used.

<Model>
1. 1. The layer structure of the layer structure model is the same as the cross-sectional structure of the display device of the embodiment of FIG.
2. 2. Model size The length was 100 mm, the thickness was the total thickness of each member having the cross-sectional structure shown in FIG. 12, and a mesh was created in two dimensions of thickness and length.
3. 3. Bending method As shown in Fig. 5, a curve with a length of 48 mm is set at both ends, the end 10 mm of the mesh is fixed to the curve (rigid body model), the curve on the left side is rotated 180 °, and the outermost surface of the mesh is on the outside. I bent it so that it became. The bending diameter was 4 mm, which was the distance between the outermost surfaces of the mesh facing each other in parallel when the curve on the left side was rotated by 180 °.
4. Input of physical property values of each layer For window film, polarizing element protective film, polarizing element, transparent resin base material for touch sensor member, alternative transparent resin base material for panel member, protective member), the strain-strain of the tensile test of each member The strain and stress of the curve data were converted to true strain (ln (strain +1), true stress (stress × (strain +1)), respectively, and the type was entered in the table as signed_eq_mechanical_Strain. Selected the stress-strain curve of the material in question from the table, with the type subelastic.

ここで、γ＝ε＋１であり、ｆは公称応力、εは公称ひずみである。 For the adhesive layer, first, the strain-stress curve data of the tensile test was fitted by the following Mooney-Rivlin equation, and the coefficients C10, C01, and C11 were calculated. Then, the type of the material property of the corresponding part of the mesh was set to Mooney, and the calculated coefficients C10, C01, and C11 were input.

Here, γ = ε + 1, f is the nominal stress, and ε is the nominal strain.

For the retardation film, the type of material property of the relevant part of the mesh is isotropic elasto-plastic, and the laminate of the retardation film, the polarizing element, and the polarizing element protection film, which are the optical film members obtained by the tensile test. Strain-test force curve data and strain-test force curve data of the laminate of the stator and protector protective film obtained in the tensile test-strain of the retardation film-test force The strain in the range of 0.05% to 0.25% in the curve corresponding to the strain-stress curve of the retardation film obtained by dividing the value of the curve corresponding to the curve by the cross-sectional area (width x thickness) of the retardation film. The slope of the curve in was calculated, and this was input as the elastic modulus of the retardation film.

Similarly, for the ITO layer, the alternative ITO layer, and the hard coat layer, the material property type of the corresponding part of the mesh is isotropic elasto-plastic, and the transparent resin group with the ITO layer, which is a touch sensor member obtained by the tensile test, is used. Material strain-Strain of test force curve and transparent resin base material of touch sensor member-Difference between test force curve data, strain of alternative transparent resin base material with alternative ITO layer, which is a panel member obtained by tensile test-Test The difference between the force curve and the strain of the transparent resin base material that substitutes for the panel member-the test force curve, the strain of the window film with a hard coat layer obtained in the tensile test-the test force curve and the strain of the window film-the test force curve The elasticity calculated based on the difference was input.

<Simulation result>
For each member of each Example and each Comparative Example, the strain (Elastic Strain in Preferred Sys) (see FIG. 6) in the direction orthogonal to the bending radius direction of the bent portion was calculated. The strain in the direction orthogonal to the bending radius direction of the bent portion calculated for Comparative Examples 1 and 9 to 11, Examples 28, 4, 8 and 11, Examples 8 and 14 to 16, and Examples 17 to 20 is applied. The distribution in the stacking direction is shown in FIGS. 8 to 11.

Further, with respect to the hard coat layer, the polarizing element protective film, the ITO layer, and the thin film encapsulating layer alternative ITO layer of each Example and each Comparative Example, the most of the strains in the direction orthogonal to the bending radius direction of the bent portion is calculated. Tables 2-1 to 2-3 show the values of the outer layer and whether or not the elongation of each layer and the film was less than the elongation at break.

Further, for each Example and each Comparative Example, A / A', 1.7A / A'-0.15-B / B', which was obtained from the calculated strain in the direction orthogonal to the bending radius direction of the bent portion. Each value of B / B'is shown in Tables 2-1 to 2-3. Further, FIG. 11 shows a diagram showing the relationship between A / A'and B / B.

(Evaluation of crack occurrence)
For the samples of the dummy display devices obtained in Examples 4, 8, 11, 14-18, 20, 24 to 26, and Comparative Examples 1, 2 and 4, the hard coat layer, the polarizing element protective film, and ITO were obtained at the time of bending. It was confirmed whether or not cracks occurred in the layer and the ITO layer instead of the thin film sealing layer.

Specifically, as shown in FIG. 12, the display device is bent 180 degrees, the outside of the bent display device is pressed by a glass plate, and a 4 mm plate is inserted between the glass plates to make the display device parallel. The bent state was maintained so that the distance between the outermost surfaces facing each other was maintained at 4 mm, and cracks in each layer and film were evaluated. Similar to the simulation model, the bending diameter was set to 4 mm as the distance between the outermost surfaces of the display device facing each other in parallel when the display device was bent at an angle of 180 °.

For the ITO layer and the thin film encapsulating layer alternative ITO layer, the occurrence of cracks was evaluated based on whether or not the resistance value of the ITO layer increased after bending. For the resistance value, a conductive tape (strip-shaped terminal) was attached to the surface of the ITO layer, arranged so that the resistance could be measured from the outside of the display device, and the resistance value was measured with a tester. The ITO layer used had a sheet resistance of 50 Ω / □, and the resistance value between the strip-shaped terminals before bending was about 165 Ω, but the resistance value in the bent state was 1. It was evaluated that cracks occurred in those that became 1 times or more.

For the hard coat layer and the polarizing element protective film, the occurrence of cracks was evaluated by microscopic observation after bending or cross-sectional SEM observation.

The crack evaluation results of each Example and each Comparative Example are shown in Tables 2-1 to 2-3.

(Calculation of breaking elongation)
Regarding the breaking elongation of the polarizing element protective film, the breaking elongation was calculated as follows. First, a bending test similar to the bending test used in the above-mentioned crack generation evaluation was performed with different bending diameters, and the bending diameter at which cracks occurred was confirmed. Then, using the bending diameter at which the crack occurs as the bending diameter and the polarizing element protective film single layer as a model, the same simulation as the above simulation is performed, and the strain in the direction orthogonal to the bending radius of the bending portion is calculated and calculated. It was set to break elongation.

Regarding the breaking elongation of the hard coat layer, the ITO layer, and the alternative ITO layer, the breaking elongation of the window film, the transparent resin base material, and the alternative transparent resin base material on which the hard coat layer is laminated is the breaking elongation of the polarizing element protective film. It was calculated by the same calculation method as the elongation calculation method, and this was taken as each breaking elongation.

Tables 2-1 to 2-3 show the calculated elongation at break of the hard coat layer, the polarizing element protective film, the ITO layer, and the alternative ITO layer of each Example and each Comparative Example.

(evaluation)
From Tables 2-1 to 2-3 and FIG. 11, the following was found. That is, 0.3 <A / A'<1.2 ... (1), B / B'<1.7A / A'-0.15 ... (2), 0 <B / B'< 1.25 ... In the display devices of Comparative Examples 1 to 5 that do not satisfy (3), the elongation of the ITO layer when bent and deformed calculated by simulation is 1.50, which is the breaking elongation of the ITO layer. Was exceeded. That is, it was shown that the ITO layer was broken. Even in the display devices of Comparative Examples 1, 2 and 4 actually manufactured, cracks occurred in the ITO layer. On the other hand, in the display devices of Examples 1 to 31 satisfying the above formulas (1) to (3), the elongation of the ITO layer when bent and deformed calculated by simulation is the breaking elongation of the ITO layer. It was below a certain 1.50%. That is, it was shown that the ITO layer did not break. No cracks were observed in the ITO layer even in the actually produced display devices of Examples 4, 8, 11, 14-18, 20, 24 and 26. As described above, the simulation results of the examples and the comparative examples and the presence or absence of cracks in the actually prepared examples and the comparative examples were in good agreement. Therefore, in the display device of each embodiment, the elongation of the ITO layer when bent and deformed is made smaller than the elongation at break of the ITO layer by configuring the display device to satisfy the above formulas (1) to (3). That is, it was found that the breakage of the ITO layer can be suppressed.

Further, in the display devices of Examples 1 to 31, the elongation of the polarizing element protective film calculated by the simulation was also less than the elongation at break (4.00%), and the actually produced Examples 4, 8, 11, 14 to 18 were obtained. No cracks were observed in the polarizing element protective film even in the display devices of Nos. 20, 24 to 26. As described above, the simulation results of the examples and the comparative examples and the presence or absence of cracks in the actually prepared examples and the comparative examples were in good agreement. Therefore, in the display device of each embodiment, by configuring so as to satisfy the above formulas (1) to (3), the elongation of the polarizing element protective film when bent and deformed is increased from the breaking elongation of the polarizing element protective film. It was found that the size can be reduced, that is, the breakage of the polarizing element protective film can be suppressed.

Further, in the display devices of Examples 1 to 14, 19 to 24, 27, 29 to 31, the elongation of the ITO layer calculated by the simulation was less than the elongation at break, and the alternative ITO layer calculated by the simulation was obtained. The elongation was also less than the elongation at break (0.65%), and no cracks were observed in the alternative ITO layer even in the actually manufactured display devices of Examples 4, 8, 11, 14, 20, and 24. As described above, the simulation results of the examples and the comparative examples and the presence or absence of cracks in the actually prepared examples and the comparative examples were in good agreement. Therefore, in the display devices of Examples 1 to 14, 19 to 24, 27, 29 to 31, the elongation of the alternative ITO layer when bent and deformed is also smaller than the elongation of the alternative ITO layer, that is, the alternative ITO layer. It was found that the breakage of the

Further, in the display devices of Examples 1 to 17, 21, 23, 25, 26, 28 to 31, the elongation of the ITO layer calculated by the simulation was less than the elongation at break, and the hardware calculated by the simulation. The elongation of the coat layer was also lower than the elongation at break (4.00%), and no cracks were observed in the hard coat layer even in the display devices of Examples 4, 8, 11, 14 to 17, 25, and 26 actually produced. rice field. As described above, the simulation results of the examples and the comparative examples and the presence or absence of cracks in the actually prepared examples and the comparative examples were in good agreement. Therefore, in the display devices of Examples 1 to 17, 21, 23, 25, 26, 28 to 31, 0.8 <A / A'<1.2 and 0 <B / B'<0.9 are satisfied. It was found that the elongation of the hard coat layer when bent and deformed can be made smaller than the elongation of the hard coat layer, that is, the breakage of the hard coat layer can be suppressed.

Further, in the display devices of Examples 1 to 14, 21, 23, 29 to 31, bending deformation calculated by simulation for all of the ITO layer, the polarizing element protective film, the thin film encapsulating layer alternative ITO layer, and the hard coat layer. The elongation at the time of making the film is less than the elongation at break, and even in the actually manufactured display devices of the fourth, eighth, eleventh, and fourteenth embodiments, the ITO layer, the polarizing element protective film, the thin film encapsulating layer alternative ITO layer, and the hard coat layer are all provided. , No cracks were found. As described above, the simulation results of the examples and the comparative examples and the presence or absence of cracks in the actually prepared examples and the comparative examples were in good agreement. Therefore, in the display devices of Examples 1 to 14, 21, 23, 29 to 31, the display devices are configured to satisfy 0.8 <A / A'<0.975 and 0.3 <B / B'<0.9. By doing so, all the elongations of the ITO layer, the polarizing element protective film, the thin film encapsulating layer alternative ITO layer, and the hard coat layer when bent and deformed are made smaller than each layer and film, that is, each layer and film are broken. It was found that it was possible to suppress.

Table 3 shows Comparative Examples 1 and 9 to 11, Comparative Examples 2 and 12 to 14, Comparative Examples 5 and 29 to 31 of Tables 2-1 to 2-3 for easy comparison. Is a rearrangement. From Tables 2-1 to 2-3, Table 3 and FIG. 7, the following was found.

The display devices of Examples 1 to 4 were display devices having the same configuration except for the second adhesive layer, and the shear modulus G'of the second adhesive layer was larger in order, but the elongation of the ITO layer and The elongation of the ITO layer instead of the thin film sealing layer became smaller in order.

Further, the display devices of Examples 5 to 8 have the same configuration except for the second adhesive layer, and the third adhesive layer is not the adhesive layer 1 of Examples 1 to 4 but the adhesive layer 2. The shear modulus G'of the second adhesive layer was larger in order, but the elongation of the ITO layer and the elongation of the thin film encapsulating layer alternative ITO layer were smaller in order.

Further, the display devices of Comparative Examples 1 and 9 to 11 have the same configuration except for the second adhesive layer, and the third adhesive layer is the adhesive of the adhesive layers 2 of Examples 1 to 4 and the adhesive of Examples 5 to 8. It was a display device that was not the layer 3 but the adhesive layer 4, and the shear modulus G'of the second adhesive layer was larger in order, but the elongation of the ITO layer and the elongation of the thin film encapsulating layer alternative ITO layer were It became smaller in order.

Further, the display devices of Comparative Examples 2 and 12 to 14 have the same configuration except for the second adhesive layer, and the third adhesive layer is the adhesive of the adhesive layers 1 of Examples 1 to 4 and the adhesive of Examples 5 to 8. It is a display device that was not the adhesive layer 1 of the layer 2, Comparative Example 1, and Examples 9 to 11, but the adhesive layer 2, and the shear modulus G'of the second adhesive layer was larger in order. The elongation of the layer and the elongation of the ITO layer instead of the thin film sealing layer became smaller in order.

Further, the display devices of Comparative Example 5 and Examples 29 to 31 have the same configuration except for the second adhesive layer, and the first adhesive layer, the third adhesive layer, and the fourth adhesive layer are Comparative Example 2 and Example 12. The window film of the window member is not the window film 1 of Examples 1 to 14 and Comparative Examples 1 and 2, but the window film 2, and the shear elastic modulus of the second adhesive layer is the same as that of the window film 2. Where G'was larger in order, the elongation of the ITO layer and the elongation of the thin film encapsulating layer alternative ITO layer became smaller in order.

From the above, by increasing the shear modulus G'of the second adhesive layer, the elongation of the ITO layer and the elongation of the thin film encapsulating layer alternative ITO layer when bent and deformed can be reduced, that is, the ITO layer and the thin film sealing. It was found that the breakage of the ITO layer instead of the stop layer can be suppressed.

Table 4 is a rearrangement of Examples 28, 4, 8 and 11 of Tables 2-1 to 2-3 for ease of comparison. The following was found from Tables 2-1 to 2-3, Table 4, and FIG.

The display devices of Examples 28, 4, 8 and 11 were display devices having the same configuration except for the third adhesive layer, and the shear modulus G'of the third adhesive layer was larger in order. The elongation of the layer became larger in order.

Therefore, it was found that by reducing the shear modulus G'of the third adhesive layer, the elongation of the ITO layer when it is bent and deformed can be reduced, that is, the fracture of the ITO layer can be suppressed.

Table 5 is a rearrangement of Examples 8 and 14-16 in Tables 2-1 to 2-3 for ease of comparison. The following was found from Tables 2-1 to 2-3, Table 5, and FIG.

The display devices of Examples 8 and 14 to 16 had the same configuration except for the fourth adhesive layer, and the shear modulus G'of the fourth adhesive layer was larger in order, but the ITO layer. The elongation and the elongation of the ITO layer alternative to the thin film sealing layer became larger in order.

Therefore, by reducing the shear modulus G'of the fourth adhesive layer, the elongation of the ITO layer and the elongation of the thin film encapsulating layer alternative ITO layer when bent and deformed are reduced, that is, the ITO layer and the thin film encapsulation. It was found that the breakage of the layer-substituting ITO layer can be suppressed.

Table 6 is a rearrangement of Examples 8 and 21 to 22, Examples 11 and 23 to 24 in Table 1 for ease of understanding. From Tables 2-1 to 2-3, Table 6 and FIG. 10, the following was found.

The display devices of Examples 17 to 20 are display devices having the same configuration except for the first adhesive layer, and the shear modulus G'of the first adhesive layer is larger in order, but the elongation of the hard coat layer is increased. Became larger in order.

Further, the display devices of Examples 8, 21, and 22 have the same configuration except for the first adhesive layer, and the third adhesive layer is not the adhesive layer 3 of Examples 17 to 20 but the adhesive layer 4, and the fourth adhesive layer. This is a display device in which the layer is not the adhesive layer 4 of Examples 17 to 20 but the adhesive layer 1. The shear modulus G'of the first adhesive layer of Examples 8 and 21 is the same, but the thickness of the first adhesive layer of Example 21 is smaller than the thickness of the first adhesive layer of Example 8. Therefore, the hardness of the first adhesive layer is higher in Example 21 than in Example 8. Further, as described above, the shear modulus G'of the adhesive layer is the dominant factor for determining the hardness of the adhesive layer, whereas the shear modulus G'of Example 22 is the factor of Example 21. Since the shear modulus is more than twice as large as that of G', the hardness of the first adhesive layer is larger in Example 22 than in Example 21. Therefore, the hardness of the first adhesive layer was higher in order, but the elongation of the hard coat layer was higher in order.

Further, the display devices of Examples 11, 23, and 24 have the same configuration except for the first adhesive layer, and the fourth adhesive layer is not the adhesive layer 3 of Examples 17 to 20 but the adhesive layer 4. The hardness of the first adhesive layer was higher in order, but the elongation of the hard coat layer was higher in order.

From the above, it was found that by reducing the hardness of the first adhesive layer, it is possible to reduce the elongation of the hardcoat layer when it is bent and deformed, that is, to suppress the breakage of the hardcoat layer.

The arrows in the strain distribution charts of FIGS. 7 to 10 indicate whether the strain shifts in the tensile direction or the compression direction for the corresponding layer and film when the hardness of the corresponding adhesive layer is increased. It is a thing. Further, the broken line indicates the breaking elongation of each corresponding layer and film.

From FIGS. 7 to 10, in the display device of each example and each comparative example in which a plurality of layers and members are laminated via the plurality of adhesive layers, when a certain adhesive layer is made hard, the display device is bent at the time of bending. It was found that the strains of the layers and members laminated on the outside of the adhesive layer shift in the tensile direction, and the strains of the layers and members laminated on the inside of the adhesive layer shift in the compression direction.

For example, with respect to Comparative Example 1 and Examples 9 to 11, referring to FIG. 7, the shear modulus G'of the second adhesive layer is increasing in order, that is, the hardness of the second adhesive layer is increasing. As the hardness of the second adhesive layer increases, the strain on the outer layer or member of the second adhesive layer shifts in the tensile direction, and the strain on the inner layer or member of the second adhesive layer shifts in the compression direction. Was there. The same was true for the set of Examples and / or Comparative Examples of FIGS. 8 to 10.

Although the present invention has been described above with reference to the drawings for a specific embodiment, the present invention can be modified in many ways other than the configurations shown and described. Therefore, the present invention is not limited to the configurations illustrated and described, and its scope should be defined only by the appended claims and their equivalents.

100 Display device 101 Laminated structure 103 Substrate laminated body 110 Optical film member 111 Polarizing film 113 Phase difference film 115 Circularly polarized light function film Laminated body 117 Polarizer 119 Polarizer protective film 120 First adhesive layer 130 Window member 131 Hard coat layer 133 Window film 140 Second adhesive layer 150 Panel member 151 Thin film sealing layer 153 Panel base 160 Third adhesive layer 170 Touch sensor member 171 Transparent conductive layer 173 Transparent film 180 Fourth adhesive layer 190 Protective member 901 Organic EL display panel 912- 1, 912-2 Transparent conductive layer 915-1, 915-2 Base film 916-1, 916-2 Transparent conductive film 917 Spacer 920 Optical laminate 921 Polarizer 922-1, 922-2 Protective film 923 Phase difference layer 930 touch panel

Claims (9)

The optical film member, the first adhesive layer, the window member laminated on one surface of the optical film member via the first adhesive layer, the second adhesive layer, and the other surface of the optical film member. A laminated structure including a panel member laminated via a second adhesive layer, a fourth adhesive layer on the surface of the panel member opposite to the second adhesive layer, and protection laminated via the fourth adhesive layer. A foldable display device with members
The laminated structure has a layer on the surface on the side of the second adhesive layer that is more easily broken than the window member and the optical film member when bent and deformed.
The laminated structure forms a thin film encapsulating layer on the surface of the panel member on the side of the second adhesive layer, and touches the surface of the thin film encapsulating layer on the opposite side of the panel member via the third adhesive layer. The sensor members are laminated to form a transparent conductive layer on the surface of the touch sensor member opposite to the panel member.
The transparent conductive layer is laminated on the second adhesive layer as a layer that is more easily broken than the window member and the optical film member when bent and deformed.
The shear modulus of the fourth adhesive layer is smaller than the shear modulus of the second adhesive layer and smaller than the shear modulus of the third adhesive layer.
The breaking elongation of the fragile layer is larger than 1.27%.
The display device is bent at an angle of 180 ° with the window member on the outside, and the distance between the outermost surfaces of the display device facing each other in parallel is 4 mm in a state of being bent at an angle of 180 °. The strain in the direction orthogonal to the bending radial direction generated on one surface of the optical film member when bent and deformed, and the direction orthogonal to the bending radial direction generated on the surface of the window member facing the first adhesive layer. The difference from the strain of A,
The optical film member and the window member are each made of a single layer, bent at an angle of 180 °, and 180 so that the outside and the inside when bent and deformed are the same as when the display device is bent and deformed. The outside of the optical film member when the optical film member and the window member are bent and deformed so that the distance between the outermost surfaces facing each other in parallel is 4 mm in a state of being bent at an angle of °. The difference between the strain in the direction orthogonal to the bending radial direction generated on the surface of the window member and the strain in the direction orthogonal to the bending radial direction generated on the inner surface of the window member is A',
The display device is bent at an angle of 180 ° with the window member on the outside, and the distance between the outermost surfaces of the display device facing each other in parallel is 4 mm in a state of being bent at an angle of 180 °. The strain in the direction orthogonal to the bending radial direction generated on the other surface of the optical film member when bent and deformed, and the direction orthogonal to the bending radial direction generated on the surface of the laminated structure facing the second adhesive layer. The difference from the strain of B,
The optical film member and the laminated structure are each made of a single layer and bent at an angle of 180 ° so that the outside and the inside when the display device is bent and deformed are the same as when the display device is bent and deformed. When the optical film member is bent and deformed so that the distance between the outermost surfaces of the optical film member and the laminated structure facing each other in parallel is 4 mm in a state of being bent at an angle of 180 °, the optical film member is formed. When the difference between the strain in the direction orthogonal to the bending radial direction generated on the inner surface of the laminated structure and the strain in the direction orthogonal to the bending radial direction generated on the outer surface of the laminated structure is B', the strain is By allowing the following equations (1), (2) and (3) to hold between the differences A, A', B and B', the elongation of the easily broken layer when bent and deformed is increased. , A display device characterized by being suppressed to a value smaller than the elongation at break.
0.3 <A / A'<1.2 ... (1)
B / B'<1.7A / A'-0.15 ... (2)
0 <B / B'<1.25 ... (3) The display device according to claim 1, wherein the window member has a hard coat layer on a surface opposite to the first adhesive layer. The display device according to claim 1 or 2, wherein the optical film member is a circularly polarizing functional film laminate in which a retardation film is laminated on a polarizing film. The display device according to claim 3, wherein the polarizing film is a laminate in which a polarizing element protective film is laminated on at least one surface of a polarizing element and a polarizing element. The display device according to claim 4, wherein the polarizing element protective film contains an acrylic resin. The display device according to any one of claims 1 to 5, wherein the layer that is more easily broken than the window member and the optical film member is a thin film sealing layer formed on the surface of the panel member on the side of the second adhesive layer. The display device according to any one of claims 2 to 6 , wherein the relationship of the following formula (4) further holds between the differences A and A'with the strain.
0.8 <A / A'・ ・ ・ ・ (4) The display device according to any one of claims 1 to 7 , wherein the shear modulus of the second adhesive layer is larger than the shear modulus of the first adhesive layer. Used in the display device according to any one of claims 1 to 8.
With the optical film member
The window member laminated on one surface of the optical film member via the first adhesive layer, and the window member.
A touch sensor member including the transparent conductive layer laminated on the other surface of the optical film member via the second adhesive layer.
Base material laminate having.

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