JP2020149065A - Laminate for organic el display device and organic el display device - Google Patents

Abstract

To obtain a laminate for an organic EL display device including such an optical laminate that has flexibility and is bendable while including a polarizing film, a protective film of the polarizing film, and a retardation film, and a bendable organic EL display device that includes the above laminate for an organic EL display device.SOLUTION: The laminate for an organic EL display device comprises an optical laminate and a first stress relief layer. The optical laminate includes: a polarizing film made of a polyvinyl alcohol resin having a thickness of 12 μm or less, in which a dichroic substance is oriented; a protective film made of a transparent resin material joined to a first surface of the polarizing film; and a retardation film joined to a second surface different from the first surface of the polarizing film. The first stress relief layer shows a storage modulus of 0.05 to 0.15 MPa at 25°C, and is disposed on an opposite side of the protective film to the retardation film. The optical laminate has a thickness of 120 μm or less, and is configured to be bendable.SELECTED DRAWING: Figure 2

Description

The present invention relates to a laminate for an organic EL display device including a foldable optical laminate having a polarizing film, and a foldable organic EL display device including such a laminate for an organic EL 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 film 921 and a retardation film 923 to which protective films 922-1 and 922-2 are bonded to both sides, and the polarizing film 921 is provided on the visible 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, the realization of a foldable organic EL display device, which is a more portable organic EL display device, is expected.

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, the polarizing film of the conventional organic EL display device, the protective film thereof, and the position laminated on the organic EL display panel. The optical laminate in which the retardation film is laminated hinders the flexibility of the organic EL display device.

Therefore, the present invention provides an optical laminate including a polarizing film, a protective film thereof, and a retardation film to be flexible and bendable, and a laminate for an organic EL display device including the optical laminate, and such a laminate. An object of the present invention is to realize a bendable organic EL display device including a laminate for an organic EL display device.

One aspect of the present invention includes an optical laminate and a first stress relaxation layer, wherein the optical laminate is a polarizing film made of a polyvinyl alcohol-based resin having a thickness of 12 μm or less in which a bicolor substance is oriented. A protective film made of a transparent resin material bonded to the first surface of the polarizing film and a retardation film bonded to a second surface different from the first surface of the polarizing film. The stress relaxation layer No. 1 has a storage elasticity at 25 ° C. of 0.05 to 0.15 MPa, is arranged on the opposite side of the protective film from the retardation film, and has a thickness of the optical laminate. The present invention provides a laminate for an organic EL display device, which is 120 μm or less and is characterized in that the optical laminate is foldable.

In one embodiment of the present embodiment, a bendable transparent conductive layer constituting the touch sensor can be further arranged on the opposite side of the retardation film from the protective film.

In this case, a second stress relaxation layer can be further arranged on the side opposite to the retardation film with respect to the transparent conductive layer.

In one embodiment of this aspect, a bendable transparent conductive layer constituting the touch sensor can be further arranged between the protective film and the first stress relaxation layer.

In this case, a second stress relaxation layer can be further arranged on the side opposite to the protective film with respect to the retardation film.

Another aspect of the present invention includes the above-mentioned laminate for an organic EL display device and an organic EL display panel configured to be foldable, and is for the organic EL display device on the visual side with respect to the organic EL display panel. It provides an organic EL display device in which a laminate is arranged and is configured to be foldable.

In one embodiment of the present embodiment, the window can be arranged on the visual side with respect to the laminated body for the organic EL display device.

According to the present invention, an optical laminate including a polarizing film, a protective film thereof, and a retardation film is made flexible and bendable, and a laminate for an organic EL display device including the optical laminate, and such a laminate. A foldable organic EL display device including a laminate for an organic EL display device can be realized.

Hereinafter, embodiments of the optical laminate 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 organic EL display device by one Embodiment of this invention. It is sectional drawing which shows the organic EL display device by another embodiment of this invention. It is sectional drawing which shows the organic EL display device by still 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 manufacturing method of the retardation film used in another Example. It is a figure which shows the measuring method of the folding resistance.

[Laminate for organic EL display device]
The laminate for an organic EL display device of the present invention includes an optical laminate and a first stress relaxation layer.

[Optical laminate]
The optical laminate of the present invention comprises a polarizing film made of a polyvinyl alcohol-based resin having a thickness of 12 μm or less in which a dichroic substance is oriented, and a protective film of a transparent resin material bonded to the first surface of the polarizing film. It includes a retardation film bonded to a second surface different from the first surface of the polarizing film.

The thickness of the optical laminate of the present invention is 120 μm or less.

The optical laminate of the present invention is configured to be bendable.

<Polarizing film>
As the polarizing film used in the optical laminate of the present invention, an iodine-oriented polyvinyl alcohol-based resin that has been stretched by a stretching step such as aerial stretching (dry stretching) or boric acid water stretching step can be used.

As a typical method for producing a polarizing film, a production method including a step of dyeing a single layer of a PVA-based resin and a step of stretching as described in JP-A-2004-341515 (single-layer stretching method). ). In addition, JP-A-51-06644, JP-A-2000-338329, JP-A-2001-343521, International Publication No. 2010/100917, JP-A-2012-073563, JP-A-2011-2816 Examples thereof include a manufacturing 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 problems such as breakage due to stretching because it is supported by the stretching resin base material.

The production method including the step of stretching in the state of the laminated body and the step of dyeing is as described in JP-A-51-069644, JP-A-2000-338329, and JP-A-2001-343521 described above. There is an aerial stretching (dry stretching) method. Then, in that it can be stretched at a high magnification and the polarization performance can be improved, a step of stretching in an aqueous boric acid solution as described in International Publication No. 2010/100917 and JP2012-0756363 is performed. A production method including the above is preferable, and a production method (two-stage stretching method) including a step of performing auxiliary stretching in the air before stretching in an aqueous boric acid solution as in JP-A-2012-0756363 is particularly preferable. Further, as described in Japanese Patent Application Laid-Open No. 2011-2816, a manufacturing method in which a PVA-based resin layer and a stretching resin base material are stretched in a laminated state, the PVA-based resin layer is excessively dyed, and then decolorized. (Excessive dyeing and decolorization method) is also preferable. The polarizing film used in the optical laminate of the present invention is made of a polyvinyl alcohol-based resin in which iodine is oriented as described above, and is a polarizing film stretched in a two-step stretching step consisting of auxiliary stretching in the air and stretching in boric acid in water. can do. Further, the polarizing film used for the optical laminate of the present invention is made of a polyvinyl alcohol-based resin in which iodine is oriented as described above, and the laminated body of the stretched PVA-based resin layer and the stretching resin base material is excessively dyed. Then, the polarizing film produced by decoloring can be obtained.

The thickness of the polarizing film used in the optical laminate of the present invention is 12 μm or less, preferably 9 μm or less, more preferably 6 μm or less, and further preferably 5 μm or less.

<Phase difference film>
As the retardation film used for the optical laminate of the present invention, one obtained by stretching a polymer film or one in which a liquid crystal material is oriented and immobilized can be used. In the present specification, the retardation film has birefringence in the in-plane and / or thickness direction.

Examples of the retardation film include an antireflection retardation film (see Japanese Patent Application Laid-Open No. 2012-133303 [0221] and [0222] [0228]) and a viewing angle compensation retardation film (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.

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

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

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 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 circular 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 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, even more excellent display characteristics can be obtained, for example, when the retardation film is used for an organic EL display.

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

In the present specification, NZ refers to the ratio of nx-nz, which is birefringence in the thickness direction, to nx-ny, which is birefringence in the plane (also referred to as Nz coefficient).

The NZ of the retardation film of the present invention is 0 to 1.3, preferably 0 to 1.25, and more preferably 0 to 1.2.

The refractive index anisotropy of the retardation film of the present invention preferably satisfies the relationship of nx> ny, preferably nx> ny ≧ nz.

For example, in the case of normal longitudinal stretching, width shrinkage occurs because the width direction is not fixed with respect to stretching in the longitudinal direction of the film. Therefore, the molecules are oriented in a more uniaxial direction, and the relationship of the refractive index is, for example, nx> ny = nz. In this case, the bending strength in the longitudinal direction of the film, which is the stretching direction, becomes strong, but the folding resistance in the width direction becomes very weak. In order to solve this, a state in which a force for regulating the width is generated in an angle direction intersecting the stretching direction (for example, in the case of lateral uniaxial stretching, in a direction perpendicular to the width direction of the film which is the stretching direction). A force is generated to make the length of a film constant in the longitudinal direction), and by stretching, the molecules can be oriented not only in the stretching direction but also in the angular direction that intersects the stretching direction. The relationship of the refractive index can be nx> ny> nz. As a result, both the folding resistance in the stretching direction and the folding resistance in the width direction can be achieved at a high level.

The absolute value of the photoelastic coefficient of the retardation film at 23 ° C.; C (m ² / N) is 2 × 10 ^{-12 to} 100 × 10 ^-12 (m ² / N), preferably 2 × 10 ^-12 to. It is 50 × 10 ^-12 (m ² / N). Due to the shrinkage stress of the polarizing film, the heat of the display panel, and the surrounding environment (moisture resistance / heat resistance), a force is applied to the retardation film, and the change in the retardation value caused by this can be prevented, resulting in good results. It is possible to obtain a display panel device having various display uniformity. Preferably, the C of the retardation film is 3 × 10 ^{-12 to} 45 × 10 ^-12 , and particularly preferably 10 × 10 ^-12 to 40 × 10 ^-12 or less. By setting C in the above range, it is possible to reduce changes and unevenness in the retardation value that occur when a force is applied to the retardation film. Further, the photoelastic modulus and Δn tend to have a trade-off relationship, and within this photoelastic modulus range, it is possible to maintain the display quality without reducing the phase difference expression.

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 suitable stretching method can be adopted depending on the intended 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, or the like can be used. Preferably, the stretching machine is provided with temperature control means. When stretching 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.

Diagonal stretching involves continuously delivering the unstretched resin film in the longitudinal direction and continuously stretching the unstretched resin film in a direction forming an angle in the specific range with respect to the width direction. As a result, it is possible to obtain a long retardation film in which the angle (alignment angle θ) formed by the width direction of the film and the slow axis is in the specific range.

As a method of diagonally stretching, the unstretched resin film is continuously stretched in a direction forming an angle of the specific range with respect to the width direction of the unstretched resin film, and the slow axis is stretched in the specific range with respect to the width direction of the film. It is not particularly limited as long as it can be formed in an angled direction. Any suitable method can be adopted from such stretching methods previously known such as JP-A-2005-319660, JP-A-2007-30466, JP-A-2014-194482, Special Opening 2014-199483, JP-A-2014-199483 and the like. it can.

As the temperature at which the unstretched resin film is stretched (stretching temperature), an appropriate value can be appropriately selected depending on the intended purpose. Preferably, the stretching is carried out in the range of Tg-20 ° C. to Tg + 30 ° C. with respect to the glass transition temperature (Tg) of the polymer film. By selecting such a condition, the retardation value tends to be uniform, and the film is less likely to crystallize (white turbidity). Specifically, the stretching temperature is 90 ° C. to 210 ° C., more preferably 100 ° C. to 200 ° C., and particularly preferably 100 ° C. to 180 ° C. The glass transition temperature can be determined by the DSC method according to JIS K 7121 (1987).

Any suitable means can be adopted as the means for controlling the stretching temperature. Examples of the temperature control means include an air circulation type constant temperature oven in which hot air or cold air circulates, a heater using microwaves or far infrared rays, a roll heated for temperature control, a heat pipe roll, a metal belt, and the like. ..

The magnification for stretching the unstretched resin film (stretching magnification) can be appropriately selected depending on the intended purpose. The draw ratio is preferably more than 1 and 6 times or less, and more preferably more than 1.5 times and 4 times or less.

The feed rate during stretching is not particularly limited, but is preferably 0.5 m / min to 30 m / min, more preferably 1 m / min to 20 m / min, from the viewpoint of mechanical accuracy, stability, and the like. Under the above stretching conditions, not only the desired optical characteristics can be obtained, but also a retardation film having excellent optical uniformity can be obtained.

Also. As another embodiment, using a polycycloolefin film, a polycarbonate film, or the like, the angle between the absorption axis of the polarizing plate and the slow axis of the 1/2 wave plate is 15 °, and the absorption axis of the polarizing plate and 1 /. A retardation film laminated with a single-wafer using an acrylic pressure-sensitive adhesive may be used so that the angle formed by the slow axis of the four-wave plate is 75 °.

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 the liquid crystal compound, the difference between nx and ny of the obtained retardation layer can be made much larger than that of 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 (finally, the organic EL display device). As used herein, the term "oriented 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, if the liquid crystal monomers are polymerized or crosslinked with each other, the oriented state can be fixed. Here, the polymer is formed by polymerization, and the three-dimensional network structure is formed by cross-linking, 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 (US521187), EP66137 (US4388453), WO93 / 22397, EP02671712, DE19504224, DE4408171, GB2280445 and the like 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-Sillicon-CC3767. As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferable.

The alignment treatment of the liquid crystal compound is performed on the surface of a predetermined base material, 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 polarizing film. At this time, the angle formed by the absorption axis of the polarizing film and the slow axis of the liquid crystal oriented solidifying layer is arranged so as to be 15 °. The phase difference of the liquid crystal oriented solidified layer is λ / 2 (about 270 nm) with respect to a 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 film 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 film and the slow-phase axis of the 1/4 wave plate is 75 °.

As the orientation treatment, any appropriate orientation treatment can be adopted. Specific examples thereof include mechanical orientation treatment, physical orientation treatment, and chemical orientation treatment. Specific examples of the mechanical orientation treatment include a rubbing treatment and a stretching treatment. Specific examples of the physical orientation treatment include magnetic field orientation treatment and electric field orientation treatment. Specific examples of the chemical alignment treatment include an orthorhombic deposition method and a photoalignment treatment. As the treatment conditions for the various orientation treatments, any appropriate conditions can be adopted depending on the purpose.

The orientation of the liquid crystal compound is performed by treating at a temperature indicating the liquid crystal phase according to the type of the liquid crystal compound. By performing such temperature treatment, the liquid crystal compound takes a liquid crystal state, and the liquid crystal compound is oriented according to the orientation treatment direction of the substrate surface.

In one embodiment, the orientation state is fixed by cooling the liquid crystal compound oriented as described above. When the liquid crystal compound is a polymerizable monomer or a crosslinkable monomer, the orientation state is fixed by subjecting the liquid crystal compound oriented as described above to a polymerization treatment or a crosslinking treatment.

Specific examples of the liquid crystal compound and details of the method for forming the oriented solidified layer are described in JP-A-2006-163343. The description of this publication is incorporated herein by reference.

[Protective film]
As the protective film of the transparent resin material used in the optical laminate of the present invention, a cycloolefin resin such as norbornene resin, an olefin resin such as polyethylene or polypropylene, a polyester resin, a (meth) acrylic resin or the like may be used. it can.

The thickness of the protective film used for the optical laminate of the present invention is 10 to 50 μm, preferably 15 to 45 μm, and a surface treatment layer such as an antiglare layer or an antireflection layer can be appropriately provided.

The permeation humidity of the 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.

[First stress relaxation layer]
The first stress relaxation layer used in the laminate for an organic EL display device of the present invention is arranged on the opposite side of the protective film from the retardation film.

The pressure-sensitive adhesive layer constituting the first stress relaxation layer used in the laminate for the organic EL display device of the present invention is 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, or a polyester-based pressure-sensitive adhesive. Examples thereof include adhesives, polyamide-based adhesives, urethane-based adhesives, fluorine-based adhesives, epoxy-based adhesives, and polyether-based adhesives. The pressure-sensitive adhesives constituting the pressure-sensitive adhesive layer may be used alone or in combination of two or more. Acrylic adhesives are preferably used from the viewpoints of transparency, processability, durability and the like.

The thickness of the pressure-sensitive adhesive layer constituting the first stress relaxation layer used in the laminate for an organic EL display device of the present invention is 10 to 250 μm, preferably 10 to 150 μm, and even a single layer has a laminated structure. You may.

The total light transmittance (according to JIS K 7136) in the visible light wavelength region of the first stress relaxation layer used in the laminate for an organic EL display device of the present invention is preferably 85% or more, more preferably 90% or more. is there.

The haze of the first stress relaxation layer (according to JIS K 7136) used in the laminate for an organic EL display device of the present invention is 3.0% or less, more preferably 2.0% or less.

The total light transmittance and the haze can be measured using, for example, a haze meter (manufactured by Murakami Color Technology Research Institute, trade name "HM-150").

The storage elastic modulus (G') of the first stress relaxation layer used in the laminate for an organic EL display device of the present invention is 0.05 to 0.15 (MPa) at 25 ° C.

[Transparent conductive layer]
For the transparent conductive layer of the present invention, conductive nanowires or metal mesh can be used. When a conductive nanowire or a metal mesh is used as the transparent conductive layer, the transparent conductive layer is configured to be bendable because it has excellent bending resistance and the conductivity is not easily lost even if it is bent. The conductive nanowires may be protected by a protective film.

The thickness of the transparent conductive layer of the present invention is preferably 0.01 μm to 10 μm, more preferably 0.05 μm to 3 μm, and further preferably 0.1 μm to 1 μm.

The total light transmittance of the transparent conductive layer of the present invention is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more. For example, if conductive nanowires are used, a transparent conductive layer having openings can be formed, and a transparent conductive layer having high light transmittance can be obtained.

The density of the transparent conductive layer of the present invention is preferably from ^{1.0g / cm 3 ~10.5g / cm 3} , more preferably from ^{1.3g / cm 3 ~3.0g / cm 3} .

The surface resistance value of the transparent conductive layer of the present invention is preferably 0.1Ω / □ to 1000Ω / □, more preferably 0.5Ω / □ to 500Ω / □, and even more preferably 1Ω / □ to 250Ω /. □.

As the conductive nanowire, any suitable conductive nanowire can be used as long as the effect of the present invention can be obtained. The conductive nanowire is a conductive substance having a needle-like or thread-like shape and a diameter of nanometer size. The conductive nanowires may be linear or curved. By using a transparent conductive layer made of conductive nanowires, a conductive film having excellent bending resistance can be obtained. In addition, if a transparent conductive layer made of conductive nanowires is used, the conductive nanowires form gaps to form a mesh, so that even a small amount of conductive nanowires can provide a good electrical conduction path. It can be formed and a conductive film having low electrical resistance can be obtained. Further, since the conductive wire has a mesh shape, an opening can be formed in the gap between the meshes to obtain a conductive film having high light transmittance. Examples of the conductive nanowires include metal nanowires made of metal, conductive nanowires containing carbon nanotubes, and the like.

The ratio (aspect ratio: L / d) of the thickness d to the length L of the conductive nanowire is preferably 10 to 100,000, more preferably 50 to 100,000, and particularly preferably 100. ~ 10,000. When conductive nanowires having a large aspect ratio are used in this way, the conductive nanowires can intersect well, and a small amount of conductive nanowires can exhibit high conductivity. As a result, a conductive film having high light transmittance can be obtained. In the present specification, the "thickness of conductive nanowires" means the diameter of the conductive nanowires when the cross section is circular, and the minor diameter when the cross section of the conductive nanowires is elliptical. When it is a polygon, it means the longest diagonal line. The thickness and length of the conductive nanowires can be confirmed by a scanning electron microscope or a transmission electron microscope.

The thickness of the conductive nanowires is preferably less than 500 nm, more preferably less than 200 nm, particularly preferably 1 nm to 100 nm, and most preferably 1 nm to 50 nm. Within such a range, a transparent conductive layer having high light transmittance can be formed.

The length of the conductive nanowires is preferably 2.5 μm to 1000 μm, more preferably 10 μm to 500 μm, and particularly preferably 20 μm to 100 μm. Within such a range, a conductive film having high conductivity can be obtained.

As the metal constituting the metal nanowire, any suitable metal can be used as long as it is a highly conductive metal. The metal nanowires are preferably composed of one or more metals selected from the group consisting of gold, platinum, silver and copper. Of these, silver, copper or gold is preferable, and silver is more preferable, from the viewpoint of conductivity. Further, a material obtained by plating the metal (for example, gold plating) may be used.

Any suitable method can be adopted as the method for producing the metal nanowires. Examples thereof include a method of reducing silver nitrate in a solution, a method of applying an applied voltage or a current to the surface of the precursor from the tip of the probe, pulling out a metal nanowire at the tip of the probe, and continuously forming the metal nanowire. .. In the method of reducing silver nitrate in a solution, silver nanowires can be synthesized by liquid-phase reduction of a silver salt such as silver nitrate in the presence of a polyol such as ethylene glycol and polyvinylpyrrolidone. Uniform size silver nanowires are available, for example, in Xia, Y. et al. etal. , Chem. Mater. (2002), 14, 4736-4745, Xia, Y. et al. etal. , Nano letters (2003) 3 (7), 955-960, can be mass-produced.

As the carbon nanotube, any suitable carbon nanotube can be used. For example, so-called multi-walled carbon nanotubes, double-walled carbon nanotubes, single-walled carbon nanotubes, and the like are used. Among them, single-walled carbon nanotubes are preferably used because of their high conductivity. Any suitable method can be adopted as the method for producing the carbon nanotubes. Preferably, carbon nanotubes produced by the arc discharge method are used. Carbon nanotubes produced by the arc discharge method are preferable because they have excellent crystallinity.

For the transparent conductive layer containing the conductive nanowires, a dispersion liquid (conductive nanowire dispersion liquid) obtained by dispersing the conductive nanowires in a solvent is applied onto the retardation film, and then the coating layer is dried. Can be formed.

Examples of the solvent contained in the conductive nanowire dispersion liquid include water, alcohol-based solvent, ketone-based solvent, ether-based solvent, hydrocarbon-based solvent, aromatic solvent and the like. From the viewpoint of reducing the environmental load, it is preferable to use water.

The dispersion concentration of the conductive nanowires in the conductive nanowire dispersion liquid is preferably 0.1% by weight to 1% by weight. Within such a range, a transparent conductive layer having excellent conductivity and light transmission can be formed.

The conductive nanowire dispersion may further contain any suitable additive depending on the intended purpose. Examples of the additive include a corrosion inhibitor that prevents corrosion of conductive nanowires, a surfactant that prevents aggregation of conductive nanowires, and the like. The type, number and amount of additives used can be appropriately set according to the purpose. In addition, the conductive nanowire dispersion liquid may contain any suitable binder resin, if necessary, as long as the effects of the present invention can be obtained.

Any suitable method can be adopted as the method for applying the conductive nanowire dispersion liquid. Examples of the coating method include spray coating, bar coating, roll coating, die coating, inkjet coating, screen coating, dip coating, slot die coating, letterpress printing method, intaglio printing method, gravure printing method and the like. As a method for drying the coating layer, any suitable drying method (for example, natural drying, blast drying, heat drying) can be adopted. For example, in the case of heat drying, the drying temperature is typically 100 ° C. to 200 ° C., and the drying time is typically 1 minute to 10 minutes.

When the transparent conductive layer is composed of conductive nanowires, the thickness of the transparent conductive layer is preferably 0.01 μm to 10 μm, more preferably 0.05 μm to 3 μm, and further preferably 0.1 μm to 0.1 μm. It is 1 μm. Within such a range, a conductive film having excellent conductivity and light transmission can be obtained.

When the transparent conductive layer is composed of conductive nanowires, the total light transmittance of the transparent conductive layer is preferably 80% or more, more preferably 85% or more, still more preferably 90% or more. ..

When the conductive nanowire is a metal nanowire composed of silver, the density of the transparent conductive layer is preferably 1.0 g / cm3 to 10.5 g / cm3, and more preferably 1.3 g / cm3 to 3. It is 0 g / cm3. Within such a range, a conductive film having excellent conductivity and light transmission can be obtained.

The transparent conductive layer containing the conductive nanowires can be patterned in a predetermined pattern. The shape of the pattern of the transparent conductive layer is preferably a pattern that operates well as a touch panel (for example, a capacitive touch panel). For example, Japanese Patent Application Laid-Open No. 2011-511357, JP-A-2010-164938, JP-A-2008-310550. Examples thereof include the patterns described in Japanese Patent Publication No. 2003-511799 and Japanese Patent Publication No. 2010-541109. After the transparent conductive layer is formed on the transparent substrate, it can be patterned by a known method.

As the metal mesh, any suitable metal mesh can be used as long as the effects of the present invention can be obtained. For example, a metal wiring layer provided on a film base material having a mesh-like pattern can be used.

(Film base material)
The film base material that supports the metal wiring layer may be a single layer or a plurality of layers. The thickness of the film base material is preferably 20 μm to 200 μm from the viewpoint of transparency and handleability.

The film base material has a plurality of protrusions on both sides on which a metal wiring layer is formed. By providing a plurality of protrusions on the surface of the film base material, the film base material is provided with slipperiness and abrasion resistance, and when the metal wiring layer is continuously formed, the quality is maintained high. The film formation rate can be increased to improve productivity.

The protrusions have an outer diameter D of more than 0 and 3 μm or less, preferably 0.1 μm to 2 μm, in a plan view of the surface of the film base material on the side where the metal wiring layer is formed. The outer diameter of the protrusion can be measured, for example, by observing the surface of the film base material on the side where the metal wiring layer is formed at a predetermined magnification. When the outer diameter D is 3 μm or less, it is possible to reliably prevent the metal wiring from being broken near the boundary between the surface of the film base material and the surface of the protrusion.

The height of the protrusions is preferably more than 0 and 3 μm or less, more preferably 0.1 μm to 2 μm, based on the flat surface of the film substrate.

The shape of the protrusion is substantially dome-shaped in the present embodiment, the cross section of the film base material in the surface direction is substantially circular, and the cross section in the thickness direction is substantially semicircular. However, the protrusions in the present invention are other than the dome type as long as they impart slipperiness and abrasion resistance to the film base material and can form a high-quality metal wiring layer continuously and at a high speed. It may have other shapes.

Examples of means for providing the protrusions on the film base material include a method of dispersing the lubricant inside the film base material, a method of applying a binder in which a plurality of particles are dispersed, and the like on the film surface.

The film constituting the film base material is preferably a polymer film having optically isotropic properties. In the present invention, "optically isotropic" means that the in-plane retardation value measured at a wavelength of 590 nm is less than 10 nm. If such a polymer film is used, when external light is incident on the touch sensor, the phase change of the light between the two metal wiring layers is small, so that the light reflected by each metal wiring layer is reflected by the circular polarizing film. It can be effectively blocked. This polymer film is, for example, a non-stretched film that has not been stretched.

The polymer film is, for example, a polycycloolefin film or a polycarbonate film. This polymer film can be obtained from, for example, Nippon Zeon Corporation, Teijin Chemicals Ltd., and the like.

(Metal wiring layer)
The metal wiring layer is, for example, a mesh-like pattern formed in order to impart translucency. The mesh pattern of the metal wiring layer is not particularly limited, and is, for example, a square lattice, a rhombus lattice, or a polygonal lattice.

The material for forming the metal wiring layer is not limited as long as it has electrical conductivity, but is preferably silver, copper or an alloy thereof, and more preferably copper.

The line width of the metal wiring layer is more than 5 μm and less than 8 μm, preferably more than 5.5 μm and less than 7 μm. Within such a line width range, it is possible to prevent disconnection due to protrusions on the film base material. When the wire width is 5 μm or less, the mesh pattern of the metal wiring layer becomes difficult to see, but the protrusions on the film base material increase the frequency of disconnection of the metal wiring, and mass production improves quality and reliability. It gets lower. On the other hand, when the line width is 8 μm or more, the mesh pattern of the metal wiring layer is remarkably visually recognized.

The thickness of the metal wiring layer is 0.1 μm or more and less than 0.5 μm, preferably more than 0.1 μm and 0.4 μm or less, and more preferably 0.15 μm to 0.35 μm. By making the thickness of the metal wiring layer thinner than, for example, 2 μm, the mesh pattern is further prevented from being visually recognized. In such a configuration, when external light is incident on the touch sensor from an oblique direction, the side surface of the metal wiring layer does not shine and is difficult to see.

The metal wiring layer is characterized in that it has a flat shape, and the ratio of the line width to the thickness (line width / thickness) is preferably 10 or more and less than 80, and more preferably 15 to 50. A touch sensor that satisfies such a relationship is excellent in productivity, does not cause disconnection of the metal wiring, and it is difficult to visually recognize the mesh pattern of the metal wiring layer.

Sectional area of the metal wiring layer, in order to obtain the electrical conductivity required for a touch panel sensor, preferably 0.5μm ² ~4μm ^2, more preferably from 0.5μm ² ~3.2μm ^2, particularly preferably is a 0.5μm ² ~2.5μm ^2.

The pitch interval of the metal wiring layer is preferably 200 μm to 800 μm, and more preferably 350 μm to 650 μm in order to obtain sufficient translucency. The aperture ratio of the metal wiring layer is preferably 95% to 99%, more preferably 96% to 99%.

As a method of forming the metal wiring layer, for example, after forming a metal layer on the entire surface of a film substrate, a predetermined resist pattern is laminated on the metal layer, and etching is performed. A method is used in which the resist is peeled off after removing the metal layer in an unnecessary region so that a mesh-like metal wiring layer is formed. The metal layer can be formed by, for example, a sputtering method, a plating method, or a combination thereof.

The transparent conductive layer of the present invention constitutes a touch sensor and is configured to be bendable.

The transparent conductive layer of the present invention can be arranged on the opposite side of the retardation film from the protective film.

The transparent conductive layer of the present invention can be arranged between the protective film and the first stress relaxation layer.

[Second stress relaxation layer]
The second stress relaxation layer used in the laminated body for an organic EL display device of the present invention relates to the transparent conductive layer when the transparent conductive layer is arranged on the side opposite to the protective film with respect to the retardation film. It can be arranged on the opposite side of the retardation film.

When the transparent conductive layer is arranged between the protective film and the first stress relaxation layer, the second stress relaxation layer used for the laminated body for the organic EL display device of the present invention has a reference to the retardation film. It can be arranged on the opposite side of the protective film.

[Organic EL display device]
The organic EL display device of the present invention includes the above-mentioned laminated body for an organic EL display device and an organic EL display panel configured to be foldable, and the organic EL display device is laminated on the visual side with respect to the organic EL display panel. The body is arranged and configured to be foldable.

Although optional, a window can be arranged on the visual side with respect to the laminated body for the organic EL display device.

FIG. 2 is a cross-sectional view showing one embodiment of the organic EL display device according to the present invention. The organic EL display device 100 includes a laminate 110 for an organic EL display device and an organic EL display panel 101 configured to be foldable. Then, the laminated body 110 for the organic EL display device is arranged on the visual side with respect to the organic EL display panel 101, and the organic EL display device 100 is configured to be bendable.

Although optional, a transparent window 102 can be arranged on the visual side with respect to the laminated body 110 for the organic EL display device.

The laminated body 110 for an organic EL display device includes an optical laminated body 120 and an adhesive layer constituting the first stress relaxation layer 111.

The optical laminate 120 includes a polarizing film 121, a protective film 122 made of a transparent resin material, and a retardation film 123. The protective film 122 made of a transparent resin material is joined to the first surface of the polarizing film 121 on the visible side. The retardation film 123 is joined to a second surface different from the first surface of the polarizing film 121. The polarizing film 121 and the retardation film 123, for example, generate circularly polarized light or have a viewing angle in order to prevent light incident inside from the viewing side of the polarizing film 121 from being internally reflected and emitted to the viewing side. It is for compensating for.

In the present embodiment, the protective film is provided on both sides of the conventional polarizing film, whereas the protective film is provided on only one side, and the polarizing film itself is also used in the conventional organic EL display device. The thickness of the optical laminate 120 is reduced by using a polarizing film having a thickness of 12 μm or less, which is much thinner than the polarizing film. Further, since the polarizing film 121 is much thinner than the polarizing film used in the conventional organic EL display device, the stress due to expansion and contraction generated under temperature or humidity conditions becomes extremely small. Therefore, the possibility that the stress generated by the shrinkage of the polarizing film causes deformation such as warpage in the adjacent organic EL display panel 101 is greatly reduced, and the display quality is significantly deteriorated and the panel encapsulating material is significantly destroyed due to the deformation. Can be suppressed.

The storage elastic modulus of the first stress relaxation layer 111 at 25 ° C. is 0.05 to 0.15 MPa, and is arranged on the side opposite to the retardation film 123 with respect to the protective film 122.

When the optical laminate 120 is bent with the protective film 122 side as the inside, the thickness of the optical laminate 120 is reduced to 120 μm or less, and the first stress relaxation layer 111 having the storage elastic modulus as described above is formed on the protective film 122. On the other hand, by arranging it on the side opposite to the retardation film 123, it is possible to reduce the stress applied to the optical laminate 120, whereby the optical laminate 120 can be bent. Further, therefore, an appropriate storage elastic modulus range may be set according to the environmental temperature in which the organic EL display device is used. For example, when the assumed operating environment temperature is 0 ° C. to 80 ° C., a first stress relaxation layer can be used so that the storage elastic modulus at 0 ° C. and the storage elastic modulus at 80 ° C. are in an appropriate numerical range.

Although optional, a bendable transparent conductive layer 112 constituting the touch sensor can be further arranged on the opposite side of the retardation film 123 from the protective film 122. The transparent conductive layer 112 is configured to be directly bonded to the retardation film 123 by, for example, a manufacturing method as shown in Japanese Patent Application Laid-Open No. 2014-219667, whereby the thickness of the optical laminate 120 is reduced, and the optical laminate 120 is reduced. It is possible to further reduce the stress applied to the optical laminate 120 when the product is bent.

Although optional, an adhesive layer constituting the second stress relaxation layer 113 can be further arranged on the side opposite to the retardation film 123 with respect to the transparent conductive layer 112. In the present embodiment, the second stress relaxation layer 113 is directly bonded to the transparent conductive layer 112. By providing the second stress relaxation layer 113, the stress applied to the optical laminate 120 when the optical laminate 120 is bent can be further reduced.

The organic EL display device shown in FIG. 3 is basically the same as that shown in FIG. 2, but the transparent conductive layer 112 is not directly bonded to the retardation film 123, and optics such as a polycycloolefin or a polycarbonate film are used. The difference is that the transparent conductive layer 112 provided on the film substrate 114 having an isotropic property is bonded to the retardation film 123.

The organic EL display device shown in FIG. 4 is almost the same as that shown in FIG. 2, but in the organic EL display device shown in FIG. 2, the touch sensor is on the opposite side of the retardation film 123 from the protective film 122. In contrast to the foldable transparent conductive layer 112 that constitutes the above, in the organic EL display device of FIG. 4, a touch sensor is formed between the protective film 122 and the first stress relaxation layer 123. The difference is that the foldable transparent conductive layer 112 is arranged. Further, in the organic EL display device of FIG. 2, the second stress relaxation layer 113 is arranged on the side opposite to the retardation film 123 with respect to the transparent conductive layer 112, whereas the organic EL of FIG. 4 is arranged. The display device differs in that it is arranged on the opposite side of the retardation film 123 from the protective film 122.

The optical laminate of the present invention will be further described with reference to the following examples. The optical laminate of the present invention is not limited to these examples.

[Example 1]
[Polarizing film]
As a thermoplastic resin base material, an amorphous polyethylene terephthalate (hereinafter, also referred to as “PET”) (IPA copolymer PET) film (thickness: 100 μm) containing 7 mol% of isophthalic acid units was prepared, and the surface was corona-treated (thickness: 100 μm). 58 W / m ² / min) was applied. On the other hand, 1 wt of acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name: Gosefimer Z200 (average degree of polymerization: 1200, saponification degree: 98.5 mol%, acetoacetylation degree: 5 mol%)) % PVA (polymerization degree 4200, saponification degree 99.2%) was prepared, and a coating liquid of a PVA aqueous solution having a PVA-based resin of 5.5 wt% was prepared, and the film thickness after drying was 12 μm. It was coated so as to be, and dried in an atmosphere of 60 ° C. by hot air drying for 10 minutes to prepare a laminate having a layer of PVA-based resin on the base material.

Next, this laminate was first stretched 1.8 times at a free end in air at 130 ° C. (auxiliary stretching in the air) to produce a stretched laminate. 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 based on 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., and the single transmittance of the PVA layer constituting the polarizing film finally formed is 40 to 44%. The PVA layer contained in the stretched laminate was stained with iodine by immersing it in the stretched laminate for 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 at a stretching temperature of 70 ° C. in an aqueous boric acid solution (stretching in boric acid water) to finally complete the stretching. 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 film contained in the obtained optical film laminate was 5 μm.

[Phase difference film]
Polymerization was carried out using a batch polymerization apparatus consisting of two vertical reactors equipped with a stirring blade and a reflux condenser controlled at 100 ° C. 9,9- [4- (2-Hydroxyethoxy) phenyl] fluorene (BHEPF), isosorbide (ISB), diethylene glycol (DEG), diphenyl carbonate (DPC), and magnesium acetate tetrahydrate in a molar ratio of BHEPF / ISB / DEG / DPC / magnesium acetate = 0.348 / 0.490 / 0.162 / 1.005 / 1.00 × 10 ^-5 . After sufficiently replacing the inside of the reactor with nitrogen (oxygen concentration 0.0005 to 0.001 vol%), heating was performed with a heat medium, and stirring was started when the internal temperature reached 100 ° C. The internal temperature was brought to 220 ° C. 40 minutes after the start of the temperature rise, and the depressurization was started at the same time as controlling to maintain this temperature, and the temperature was 13.3 kPa 90 minutes after reaching 220 ° C. The phenol vapor produced as a by-product of the polymerization reaction was guided to a reflux condenser at 100 ° C., the monomer component contained in a small amount in the phenol vapor was returned to the reactor, and the uncondensed phenol vapor was guided to a condenser at 45 ° C. for recovery.

After introducing nitrogen into the first reactor and once restoring the pressure to atmospheric pressure, the oligomerized reaction solution in the first reactor was transferred to the second reactor. Then, the temperature rise and depressurization in the second reactor were started, and the internal temperature was 240 ° C. and the pressure was 0.2 kPa in 50 minutes. Then, the polymerization was allowed to proceed until the stirring power became a predetermined value. When the predetermined power is reached, nitrogen is introduced into the reactor to repressurize, the reaction solution is extracted in the form of strands, pelletized with a rotary cutter, and BHEPF / ISB / DEG = 34.8 / 49.0 /. A polycarbonate resin A having a copolymerization composition of 16.2 [mol%] was obtained. The reduced viscosity of this polycarbonate resin was 0.430 dL / g, and the glass transition temperature was 128 ° C.

After vacuum-drying the obtained polycarbonate resin at 80 ° C. for 5 hours, a single-screw extruder (manufactured by Isuzu Kakoki Co., Ltd., screw diameter 25 mm, cylinder set temperature: 220 ° C.), T-die (width 900 mm, set temperature: 220). A polycarbonate resin film having a thickness of 150 μm was produced using a film-forming device equipped with a chill roll (set temperature: 120 to 130 ° C.) and a winder.

The polycarbonate resin film obtained as described above was subjected to preheat treatment, first diagonal stretching and second diagonal stretching treatment to obtain a long retardation film. Specifically, it is as follows.

With reference to FIG. 5, a polycarbonate resin film (thickness 150 μm, width (W1) 765 mm) was conveyed while being gripped by the left and right clips 1 (grasping zone A), and preheated to 145 ° C. in the preheating zone B of the stretching apparatus. .. In the preheating zone B, the clip pitch (P1) of the left and right clips was 125 mm. Next, as soon as the film entered the first oblique stretching zone C, the clip pitch of the right side clip was increased and the clip pitch of the left side clip was decreased. The rate of change in the clip pitch (P2 / P1) of the right clip at the end of the first diagonally stretched zone C is 1.42, and the rate of change in the clip pitch of the left clip (P3 / P1) is 0.72. It was. The first diagonal stretching was performed at 138 ° C. The film width (W2) after the first diagonal stretching was 1092 mm (TD stretching ratio (W2 / W1) = 1.45 times). Next, as soon as the film entered the second diagonally stretched zone D, the clip pitch of the left clip was started to increase, increasing from P3 to P2. The rate of change (P2 / P3) of the clip pitch of the left clip in the second diagonally stretched zone D was 1.97. On the other hand, the clip pitch of the right clip was maintained at P2 in the second oblique stretching zone D. The second diagonal stretching was performed at 138 ° C. The film width (W3) after the second diagonal stretching was 1419 mm. Further, the stretching ratio (W3 / W1) in the width direction in the first diagonal stretching step and the second diagonal stretching step was 1.9 times.

Then, in the release zone, the film was held at 125 ° C. for 60 seconds for heat fixation. After cooling the heat-fixed film to 100 ° C., the left and right clips were opened (open zone E).

As described above, a long retardation film (thickness 55 μm, width 1419 mm) having an orientation angle of 48 ° was obtained.

[First stress relaxation layer]
The pressure-sensitive adhesive layer constituting the first stress relaxation layer of this example was prepared by the following method.
Butyl acrylate (BA): 67 parts by weight, cyclohexyl acrylate (CHA): 14 parts by weight, 4-hydroxybutyl acrylate (4HBA): 27 parts by weight, hydroxyethyl acrylate (HEA): 9 parts by weight, 2,2-dimethoxy- 1,2-Diphenyl-1-one (trade name "Irgacure 651", manufactured by BASF Japan): 0.05 parts by weight, and 1-hydroxy-cyclohexyl-phenyl-ketone (trade name "Irgacure 184", manufactured by BASF Japan) (Manufactured): A partial polymer (monomer syrup) having a polymerization rate of 10% was obtained by putting 0.05 parts by weight into a four-necked flask and exposing it to ultraviolet rays in a nitrogen atmosphere to partially photopolymerize it. .. To 100 parts by weight of this partial polymer, 0.1 part by weight of an isocyanate compound (trade name "Coronate L", manufactured by Nippon Polyurethane Industry Co., Ltd., solid content 75% by weight) was added in terms of solid content, and then these were uniformly mixed. To prepare a photopolymerizable composition.

This photopolymerizable composition is applied by applying it on the peeling surface of a release liner (a type in which one side of a polyethylene terephthalate film is peeled, a thickness of 38 μm, trade name “MRF38”, manufactured by Mitsubishi Resin Co., Ltd.). After forming the layer, a similar release liner was provided on the coating layer.

Next, a black light is used to irradiate ultraviolet rays with an intensity of 5 mW / cm ² and polymerize until the light is irradiated at 3600 mJ / cm ² , and an adhesive sheet (base material) provided with separators on both sides of the adhesive layer. A less type, thickness of adhesive layer: 100 μm) was prepared.

The weight average molecular weight of the acrylic polymer as the base polymer of the pressure-sensitive adhesive layer was 2 million.

[Optical laminate]
The long retardation film having a slow axis in the oblique direction obtained as described above and the long polarizing film having an absorption axis in the longitudinal direction obtained as described above are continuously connected by a roll-to-roll method. A long laminated film was prepared so that the axis angle between the slow-phase axis and the absorption axis was 45 °.

Next, the obtained long film was cut into 15 cm × 1 cm to prepare a circularly polarizing plate.

An (meth) acrylic resin film serving as a protective film was bonded to the obtained circularly polarizing plate via an adhesive to prepare an optical laminate. Further, by peeling the separator from the adhesive sheet obtained as described above and adhering the adhesive constituting the first stress relaxation layer to the (meth) acrylic resin film serving as the protective film, the organic EL display device. A laminate for use was prepared. If this adhesive layer is exposed, it will be difficult to perform the 180 ° folding resistance test described later. Therefore, PET having a thickness of 38 μm is placed on the adhesive layer of the laminate for the organic EL display device. The base materials were bonded together.

Various evaluations were performed on the obtained polarizing film, retardation film, optical laminate, pressure-sensitive adhesive layer constituting the first stress relaxation layer, and laminate for an organic EL display device as follows. Table 1 shows the characteristics of the obtained polarizing film, retardation film, optical laminate, pressure-sensitive adhesive layer constituting the first stress relaxation layer, and laminate for an organic EL display device.

[Example 2]
Except for the following differences, a polarizing film, a pressure-sensitive adhesive layer constituting the first stress relaxation layer, and a laminate for an organic EL display device were manufactured and manufactured under the same conditions as in Example 1, and various evaluations were performed as follows. Was done. The difference lies in the configuration of the retardation film. The retardation film of Example 1 was a one-layer retardation film manufactured by the oblique stretching method, but in the retardation film of this example (1/4 wavelength waveplate 6), the liquid crystal material is oriented. It was a retardation film composed of two layers, a fixed retardation layer 8 for a 1/4 wave plate and a retardation layer 9 for a 1/2 wavelength plate. Specifically, it was manufactured as follows.
(Liquid crystal material)
A polymerizable liquid crystal material exhibiting a nematic liquid crystal phase as a material for forming the retardation layer 9 for a 1/2 wave plate and the retardation layer 8 for a 1/4 wave plate (manufactured by BASF, trade name: P aliocolor LC 2 4 2). Was used. A photopolymerization initiator for the polymerizable liquid crystal material (manufactured by BASF, trade name: Irgacure 907) 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, a material such as PET, which can transfer the liquid crystal coating layer later, was used. Furthermore, 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. And cyclohexanone mixed solvent was used to dissolve in a solid content concentration of 25% to prepare a coating solution. 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, a material such as 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 process 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 process 20, the roll plate 30 is a cylindrical molding die in which an uneven shape related to the alignment film 11 for the 1/4 wave plate 6 of the 1/4 wavelength retardation plate 6 is formed on the peripheral side surface. It was. 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 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 8 for the 1/4 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 8 for the 1/4 wave plate of the base material 14 by the die 32. It was applied. In this manufacturing process 20, the roll plate 40 is a cylindrical molding die in which the uneven shape of the 1/4 wavelength retardation plate 6 related to the alignment film 13 for the 1/2 wavelength plate is formed on the peripheral side surface. It was. 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 irradiating the ultraviolet rays with the ultraviolet irradiation device 35 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 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 was cured by irradiation with ultraviolet rays by the ultraviolet irradiation device 37, and a configuration related to the retardation layer 9 for a 1/2 wavelength plate was created by these.

Various evaluations were performed on the obtained polarizing film, retardation film, optical laminate, pressure-sensitive adhesive layer constituting the first stress relaxation layer, and laminate for an organic EL display device as follows.

Table 1 shows the characteristics of the obtained polarizing film, retardation film, optical laminate, pressure-sensitive adhesive layer constituting the first stress relaxation layer, and laminate for an organic EL display device.

[Example 3]
A polarizing film, a retardation film, and optics under the same conditions as in Example 1 except that a pressure-sensitive adhesive having a storage elastic modulus at 25 ° C. of 0.05 MPa is used as the pressure-sensitive adhesive material of the pressure-sensitive adhesive layer constituting the first stress relaxation layer. Laminates and laminates for organic EL display devices were manufactured and manufactured, and various evaluations were performed as follows.

The pressure-sensitive adhesive layer constituting the first stress relaxation layer of this example was prepared by the following method.

By mixing 50 parts by weight of lauryl acrylate (LA), 32 parts by weight of 2-ethylhexyl acrylate (2EHA), 8 parts by weight of 4-hydroxybutyl acrylate (HBA) and 10 parts by weight of N-vinyl-2-pyrrolidone (NVP). A mixture (monomer mixture) was obtained. Next, 100 parts by weight of the above mixture, 0.05 part by weight of 1-hydroxy-cyclohexyl-phenyl-ketone (trade name "Irgacure 184", manufactured by BASF Japan Co., Ltd., photopolymerization initiator) and 2,2-dimethoxy-1, Add 0.05 parts by weight of 2-diphenylethane-1-one (trade name "Irgacure 651", manufactured by BASF Japan Co., Ltd., photopolymerization initiator) into a four-port flask and add viscosity (BH viscosity) under a nitrogen atmosphere. A partially polymerized monomer syrup (partially polymerized monomer component) was obtained by irradiating with ultraviolet rays until the system No. 5 rotor (10 rpm, temperature 30 ° C.) reached about 15 Pa · s and photopolymerizing.

In addition to 100 parts by weight of this partially polymerized monomer syrup, 0.04 parts by weight of 1,6-hexanediol diacrylate (HDDA, polyfunctional monomer), 1-hydroxy-cyclohexyl-phenyl-ketone (trade name "Irgacure 184", BASF Japan) Photopolymerization initiator (additional initiator) manufactured by Co., Ltd., 0.05 parts by weight and 2,2-dimethoxy-1,2-diphenylethane-1-one (trade name "Irgacure 651", manufactured by BASF Japan Co., Ltd., 0.05 parts by weight of photopolymerization initiator (additional initiator) and 0.3 parts by weight of silane coupling agent (trade name "KBM-403", manufactured by Shin-Etsu Chemical Industry Co., Ltd.) are uniformly mixed to prepare an adhesive. The composition was obtained. The above pressure-sensitive adhesive composition is applied onto the peel-treated surface of a release film (trade name "MRF # 38", manufactured by Mitsubishi Resin Co., Ltd.) so that the thickness after forming the pressure-sensitive adhesive layer is 100 μm. , The pressure-sensitive adhesive composition layer was formed, and then a release film (trade name "MRN # 38", manufactured by Mitsubishi Resin Co., Ltd.) was attached to the surface of the pressure-sensitive adhesive composition layer. After that, ultraviolet irradiation was performed under the conditions of illuminance: 4 mW / cm2 and light intensity: 1200 mJ / cm2 to photo-cure the pressure-sensitive adhesive composition layer, and a pressure-sensitive adhesive sheet (base material-less) provided with separators on both sides of the pressure-sensitive adhesive layer. Type, thickness of adhesive layer: 100 μm) was prepared.

Table 1 shows the characteristics of the obtained polarizing film, retardation film, optical laminate, pressure-sensitive adhesive layer constituting the first stress relaxation layer, and laminate for an organic EL display device.

[Comparative Example 1]
[Polarizing film]
A polyvinyl alcohol film having a thickness of 50 μm is immersed in the following 5 baths [1] to [5] through a plurality of sets of rolls having different peripheral speeds while sequentially applying tension in the longitudinal direction of the film, and the final draw ratio is the film. It was stretched so as to be 6.0 times the original length. This film was dried in an oven at 50 ° C. for 4 minutes to obtain a polarizing film having a thickness of 22 μm.
[1] Swelling bath: Pure water at 30 ° C. [2] Dyeing bath: The iodine concentration is in the range of 0.02 to 0.2% by weight and the potassium iodide concentration is 0.14 to 0.2% by weight with respect to 100 parts by weight of water. It was within the range of 1.4% by weight. The ratio of iodine to potassium iodide concentrations is 1: 7. The final polarizing film was immersed in an aqueous solution containing these at 30 ° C. for an arbitrary time so that the single transmittance of the polarizing film was 40 to 44%.
[3] First cross-linking bath: An aqueous solution at 40 ° C. containing 3% by weight of potassium iodide and 3% by weight of boric acid.
[4] Second cross-linking bath: An aqueous solution at 60 ° C. containing 5% by weight of potassium iodide and 4% by weight of boric acid.
[5] Washing bath: An aqueous solution at 25 ° C. containing 3% by weight of potassium iodide.

[Phase difference film]
Isosorbide (hereinafter, may be abbreviated as "ISB") may be abbreviated as 445.1 parts by weight, 9,9- (4- (2-hydroxyethoxy) phenyl) fluorene (hereinafter, may be abbreviated as "BHEPF"). ) Is 906.2 parts by weight, polyethylene glycol having a molecular weight of 1000 (hereinafter, may be abbreviated as “PEG # 1000”) 15.4 parts by weight, diphenyl carbonate (hereinafter, may be abbreviated as “DPC”). ) Is 1120.4 parts by weight, and 6.27 parts by weight of cesium carbonate (0.2 wt% aqueous solution) is charged into the reactor as a catalyst, and the first step of the reaction is carried out under a nitrogen atmosphere. The temperature of the heat medium of the reaction vessel was set to 150 ° C., and the raw materials were dissolved while stirring as necessary (about 15 minutes). Next, the pressure inside the reaction vessel was changed from normal pressure to 13.3 kPa, and the heat medium temperature of the reaction vessel was raised to 190 ° C. in 1 hour, and the generated phenol was extracted from the reaction vessel.

After maintaining the temperature inside the reaction vessel at 190 ° C. for 15 minutes, as the second step, the pressure inside the reaction vessel was set to 6.67 kPa, and the heat medium temperature of the reaction vessel was raised to 230 ° C. in 15 minutes. The generated phenol was extracted from the reaction vessel. Since the stirring torque of the stirrer increased, the temperature was raised to 250 ° C. in 8 minutes, and the pressure in the reaction vessel was reduced to 200 Pa or less in order to remove the generated phenol. After reaching the predetermined stirring torque, the reaction is terminated, the produced reaction product is extruded into water, and then pelletized, and BHEPF / ISB / PEG # 1000 = 40.3 mol% / 59.4 mol% / 0. A 3 mol% polycarbonate resin A was obtained.

After vacuum-drying the obtained polycarbonate resin A at 80 ° C. for 5 hours, a single-screw extruder (manufactured by Isuzu Kakoki Co., Ltd., screw diameter 25 mm, cylinder set temperature: 220 ° C.), T-die (width 200 mm, set temperature: 220). A film-forming device equipped with a chill roll (set temperature: 120 to 130 ° C.) and a winder was used to prepare a raw film having a thickness of 110 μm. A sample having a width of 6 cm and a length of 6 cm was cut out from this raw film, and the thickness unevenness was measured. This sample was stretched at a stretching rate of 720 mm / min (strain rate) so that R1 (550) was 130 ± 20 nm while adjusting the stretching temperature at 127 to 177 ° C. using a batch type biaxial stretching device (manufactured by Toyo Seiki Co., Ltd.). A 1 × 2.0 times uniaxial stretching was performed at 1200% / min) to obtain a retardation film. At this time, in the direction perpendicular to the stretching direction, stretching was performed in a holding state (stretching ratio 1.0). As described above, a long retardation film having a thickness of 55 μm was obtained.

[First stress relaxation layer]
The pressure-sensitive adhesive layer constituting the first stress relaxation layer of this comparative example was prepared by the following method.

(Acrylic polymer)
60 parts by weight of dicyclopentanyl acrylate (DCPMA, dicyclopentanyl methacrylate), 40 parts by weight of methyl methacrylate (MMA, methyl methacrylate), 3.5 parts by weight of α-thioglycerol as a chain transfer agent, and as a polymerization solvent. 100 parts by weight of toluene was put into a four-necked flask, and these were stirred at 70 ° C. for 1 hour in a nitrogen atmosphere. Next, 0.2 parts by weight of 2,2'-azobisisobutyronitrile as a polymerization initiator was put into a four-necked flask and reacted at 70 ° C. for 2 hours, followed by a reaction at 80 ° C. for 2 hours. I let you. Then, the reaction solution was put into a temperature atmosphere of 130 ° C., and toluene, the chain transfer agent and the unreacted monomer were dried and removed to obtain a solid acrylic polymer. The weight average molecular weight of the acrylic polymer (Mw) was 5.1 × 10 ^3.

(Stress relaxation glue)
In a monomer mixture composed of 68 parts by weight of 2-ethylhexyl acrylate (2EHA), 14.5 parts by weight of N-vinyl-2-pyrrolidone (NVP) and 17.5 parts by weight of 2-hydroxyethyl acrylate (HEA). After blending 0.035 parts by weight of a photopolymerization initiator (trade name "Irgacure 184", manufactured by BASF) and 0.035 parts by weight of a photopolymerization initiator (trade name "Irgacure 651", manufactured by BASF), the viscosity ( A prepolymer composition in which a part of the above-mentioned monomer components was polymerized was obtained by irradiating ultraviolet rays until the BH viscometer No. 5 rotor (10 rpm, measurement temperature 30 ° C.) reached about 20 Pa · s.

Next, the prepolymer composition contains 5 parts by weight of the acrylic polymer, 0.30 parts by weight of hexanediol diacrylate (HDDA), a silane coupling agent (trade name "KBM-403", manufactured by Shin-Etsu Chemical Industry Co., Ltd.). ) 0.3 parts by weight was added and mixed to obtain an acrylic pressure-sensitive adhesive composition. The above pressure-sensitive adhesive composition is applied onto the peel-treated surface of a release film (trade name "MRF # 38", manufactured by Mitsubishi Resin Co., Ltd.) so that the thickness after forming the pressure-sensitive adhesive layer is 100 μm. , The pressure-sensitive adhesive composition layer was formed, and then a release film (trade name "MRN # 38", manufactured by Mitsubishi Resin Co., Ltd.) was attached to the surface of the pressure-sensitive adhesive composition layer. After that, ultraviolet irradiation was performed under the conditions of illuminance: 5 mW / cm2 and light amount: 1500 mJ / cm2 to photo-cure the pressure-sensitive adhesive composition layer to form a pressure-sensitive adhesive layer, and separators were provided on both sides of the pressure-sensitive adhesive layer. A pressure-sensitive adhesive sheet (base material-less type, thickness of pressure-sensitive adhesive layer: 100 μm) was prepared.

[Optical laminate]
A laminated long film was produced by laminating these so that the angle formed by the slow axis of the obtained retardation film and the absorption axis of the obtained polarizing film was 45 °.

Next, the obtained laminated long film was cut into a size of 15 cm × 1 cm to prepare a circularly polarizing plate.

An (meth) acrylic resin film serving as a protective film was bonded to both sides of the obtained circularly polarizing plate with an adhesive to prepare an optical laminate. Further, the separator is peeled off from the pressure-sensitive adhesive sheet obtained as described above, and the pressure-sensitive adhesive constituting the first stress relaxation layer is attached to the (meth) acrylic resin film serving as a protective film to display an organic EL. A laminate for the device was produced. If the adhesive layer is exposed, it becomes difficult to perform the 180 ° folding resistance test described later. Therefore, a PET group having a thickness of 38 μm is placed on the adhesive layer of the laminate for the organic EL display device. The materials were pasted together.

Various evaluations were performed on the obtained polarizing film, retardation film, optical laminate, pressure-sensitive adhesive layer constituting the first stress relaxation layer, and laminate for an organic EL display device as follows. Table 1 shows the characteristics of the obtained polarizing film, retardation film, optical laminate, pressure-sensitive adhesive layer constituting the first stress relaxation layer, and laminate for an organic EL display device.

[Comparative Example 2]
A polarizing film, a retardation film, and optics under the same conditions as in Comparative Example 1 except that a pressure-sensitive adhesive having a storage elastic modulus at 25 ° C. of 0.20 MPa is used as the pressure-sensitive adhesive material of the pressure-sensitive adhesive layer constituting the first stress relaxation layer. Laminates and laminates for organic EL display devices were manufactured and manufactured, and various evaluations were performed as follows.

The pressure-sensitive adhesive layer constituting the first stress relaxation layer of this comparative example was prepared by the following method.

32-weight part of 2-ethylhexyl acrylate (2EHA), 48 parts by weight of isostearyl acrylate (ISTA), 20 parts by weight of 2-hydroxypropyl acrylate (2HPA), two photopolymerization initiators (trade name: Irgacure 184, manufactured by BASF) A monomer mixture was prepared by charging 0.05 parts by weight of 0.05 parts by weight and 0.05 parts by weight of a photopolymerization initiator (trade name: Irgacure 651, manufactured by BASF) into a four-necked flask. Then, the monomer mixture was exposed to ultraviolet rays in a nitrogen atmosphere and partially photopolymerized to obtain a partial polymer (acrylic polymer syrup) having a polymerization rate of about 10% by weight. To 100 parts by weight of the obtained acrylic polymer syrup, 0.02 part by weight of trimethylolpropane triacrylate (TMPTA) and a silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added. After adding 3 parts, these were uniformly mixed to prepare a monomer component.

Next, the monomer component prepared above was peeled off on one side of a polyester film having a thickness of 38 μm (trade name: Diafoil MRF, manufactured by Mitsubishi Resin Co., Ltd.) to a final thickness of 100 μm. To form a coating layer. Next, a polyester film (trade name: Diafoil MRE, manufactured by Mitsubishi Resin Co., Ltd.) having a thickness of 38 μm, one side of which was peeled off with silicone, was applied to the surface of the coated monomer component, and the peeled surface of the film was on the coated layer side. It was coated so as to be. As a result, the coating layer of the monomer component was shielded from oxygen. Using a chemical light lamp (manufactured by Toshiba Corporation), ultraviolet rays with an illuminance of 5 mW / cm2 (measured with Topcon UVR-T1 having the maximum sensitivity at about 350 nm) are applied to the sheet having the coating layer thus obtained for 360 seconds. By irradiating, the coating layer was cured to form a pressure-sensitive adhesive layer, and a pressure-sensitive adhesive sheet (base material-less type, thickness of pressure-sensitive adhesive layer: 100 μm) provided with separators on both sides of the pressure-sensitive adhesive layer was prepared.

Table 1 shows the characteristics of the obtained polarizing film, retardation film, optical laminate, pressure-sensitive adhesive layer constituting the first stress relaxation layer, and laminate for an organic EL display device.

[Evaluation]
(Measurement of thickness)
The thicknesses of the polarizing film, the retardation film, the protective film, and the optical laminate were measured using a dial gauge (manufactured by Mitutoyo).

(Measurement of storage elastic modulus of the first stress relaxation 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 Rheometric Expansion System (ARES)" manufactured by Rheometric Scientific. The storage elastic 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 folding strength (times))
FIG. 7 shows a schematic view of a 180 ° folding resistance tester (manufactured by Imoto Seisakusho). This device has a mechanism in which the chuck on one side repeatedly bends 180 ° across the mandrel in a constant temperature bath, and the bending radius can be changed according to the diameter of the mandrel. The mechanism is such that the test stops when the film breaks. In the test, the 1 cm × 15 cm optical laminates obtained in each Example and Comparative Example were set in the apparatus, and the conditions were a temperature of 25 ° C., a bending angle of 180 °, a bending radius of 5 mm, a bending speed of 2 seconds / time, and a weight of 100 g. It was carried out in. The folding resistance was evaluated by the number of times until the optical laminate was broken. Here, when the number of bends reached 100,000, the test was terminated.

(Evaluation)
The following was found from Table 1. In Examples 1 to 3, the folding resistance of the optical laminate exceeded 100,000 times, but in Comparative Examples 1 and 2, the folding resistance was significantly lower than 40,000 times, 20,000 times, and 100,000 times, respectively. That is, in the optical laminate of each embodiment, the stress applied to the optical laminate can be effectively suppressed, the thickness of the optical laminate is 120 μm or less, and the first stress relaxation layer is stored at 25 ° C. When the elastic modulus is 0.05 to 0.15 MPa, the folding resistance is sufficiently large, the thickness of the optical laminate exceeds 120 μm, and the storage elastic modulus of the first stress relaxation layer at 25 ° C. is 0.15 MPa. It was found that if it exceeds, the folding resistance is significantly reduced.

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 Organic EL display device 101 Organic EL display panel 102 Window 110 Laminate for organic EL display device 111 First stress relaxation layer 112 Transparent conductive layer 113 Second stress relaxation layer 114 Base material 115 Base material 120 Optical laminate 121 Polarized light Film 122 Protective film 123 Phase difference layer 900 Organic EL display device 901 Organic EL display panel 912-1, 912-2 Transparent conductive layers 915-1, 915-2 Base film 916-1, 916-2 Transparent conductive film 917 spacer 920 Optical laminate 921 Polarizing film 922-1, 922-2 Protective film 923 Phase difference layer 930 Touch panel

Claims (7)

Optical laminate and
The first stress relaxation layer and
Including
The optical laminate is
A polarizing film made of a polyvinyl alcohol-based resin having a thickness of 12 μm or less in which a dichroic substance is oriented, and
A protective film made of a transparent resin material bonded to the first surface of the polarizing film,
A retardation film bonded to a second surface different from the first surface of the polarizing film,
Including
The first stress relaxation layer has a storage elastic modulus at 25 ° C. of 0.05 to 0.15 MPa, and is arranged on the opposite side of the protective film from the retardation film.
The thickness of the optical laminate was 120 μm or less, and the optical laminate was configured to be bendable.
A laminate for an organic EL display device. The laminate for an organic EL display device according to claim 1, wherein a bendable transparent conductive layer constituting a touch sensor is further arranged on the opposite side of the retardation film from the protective film. The laminate for an organic EL display device according to claim 2, wherein a second stress relaxation layer is further arranged on the side opposite to the retardation film with respect to the transparent conductive layer. The laminate for an organic EL display device according to claim 1, wherein a bendable transparent conductive layer constituting a touch sensor is further arranged between the protective film and the first stress relaxation layer. The laminate for an organic EL display device according to claim 4, wherein a second stress relaxation layer is further arranged on the side opposite to the protective film with respect to the retardation film. The laminate for an organic EL display device according to any one of claims 1 to 5,
An organic EL display panel that is foldable and
Including
The laminated body for the organic EL display device is arranged on the visual side with respect to the organic EL display panel, and is configured to be foldable.
Organic EL display device. The organic EL display device according to claim 6, wherein a window is arranged on the visual side with respect to the laminated body for the organic EL display device.

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