JP6977737B2 - Display device - Google Patents

Description

The present invention relates to a display device.

Display devices are installed in various electronic devices, from mobile devices to large TVs. Conventionally, as this display device, it has been common to use a liquid crystal display device. However, in recent years, mainly mobile devices such as notebook computers and mobile phones, electronic devices using an organic electroluminescence display device (hereinafter, may be appropriately referred to as an "organic EL display device") as a display device are increasing. It is in.

From the viewpoint of improving the design and portability of mobile devices, it is required to reduce the thickness and weight of the entire module of the mobile device. In addition, there is a demand for larger televisions. Further, in a display device, it is generally required to make the display screen highly delicate. Therefore, the optical films and polarizing plates used in these display devices are also required to be thinned, widened, and of high quality. Further, a touch panel is often used for the display window of the display device. Among several types of touch panels, the capacitive touch panel has excellent visibility and durability, as well as a multi-touch function that enlarges or reduces the image by tapping, flipping, and picking the screen with your fingertips. Touch panels are very popular. In order to meet such demands, various studies have been conducted as shown in Patent Documents 1 to 14.

International Publication No. 2016/31776 Japanese Unexamined Patent Publication No. 2014-191006 Japanese Unexamined Patent Publication No. 2010-76181 Japanese Patent No. 5821155 International Publication No. 2016/20956 International Publication No. 2014/185000 Japanese Unexamined Patent Publication No. 10-10523 Japanese Unexamined Patent Publication No. 1-204092 Japanese Unexamined Patent Publication No. 3-174512 Japanese Unexamined Patent Publication No. 2009-12454 Japanese Unexamined Patent Publication No. 2005-181615 Japanese Unexamined Patent Publication No. 2015-031753 Japanese Unexamined Patent Publication No. 05-100114 Japanese Unexamined Patent Publication No. 10-68816

Generally, in the manufacturing process of a display device, a polarizing plate is attached to a glass substrate of a display element via an adhesive or an adhesive. The polarizing plate is usually manufactured by laminating a polarizing element protective film on both sides of a polarizing element in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film. Cyclic olefin films and triacetyl cellulose films are typical examples of the polarizing element protective film. Further, the polarizing element protective film is usually laminated on both sides of the polarizing element via a liquid pressure-sensitive adhesive or an adhesive containing water or an organic solvent.

It is desirable that the polarizing plate is attached so as to reach the peripheral edge of the glass substrate of the display element. However, the polarizing element protective film may change in size due to the influence of the humidity and temperature of the external environment, the pressure-sensitive adhesive or the adhesive used, and the like. As a countermeasure against this dimensional change, a polarizing plate having a size larger than the peripheral edge of the display element is attached in advance, and then the polarizing plate protruding from the end of the glass substrate of the display element is cut without damaging the glass substrate. Is being done.

Further, it is required to freely cut the polarizing plate into a desired shape according to the screen size of the display device without damaging the glass substrate.

Further, in recent years, in particular, in the manufacturing process of a display device, a "roll-to-panel manufacturing method" in which a roll-shaped polarizing plate and a panel provided with a display element are directly bonded to each other has been adopted. The roll-shaped polarizing plate manufactured by such a roll-to-panel manufacturing method is cut to a desired size.

In addition, there is a demand for widening the width of the film as the screen size increases. In response to this requirement, a wide stretched film is manufactured by fixing the widthwise end portion of the roll-shaped raw film produced by the melt casting method, the solution casting method, etc. with a clip and laterally stretching the film. Has been done. However, since both ends of the stretched film have clip marks, it is usually required to cut the unnecessary portions.

On the other hand, the touch panel generally includes a translucent cover panel that is arranged in the display window and functions as a dielectric. A capacitive film sensor is usually adhered to the back surface of the cover panel via an adhesive layer or an adhesive layer. This film sensor is provided on the base material, the first electrode portion provided on the surface of one side (observer side) of the base material, and the surface of the other side (display device side) of the base material. It has a second electrode portion and the like. Then, in such a film sensor, a desired portion of one side surface and the other side surface of the base material is cut to form a routing wiring having conductivity.

Examples of the method for cutting the polarizing element protective film and the polarizing plate into a desired shape include a mechanical cutting method using a knife and a laser cutting method using a laser beam. However, mechanical cutting may result in invisible scratches and non-uniform residual stress. Under these circumstances, in recent years, the adoption of a laser cutting method is required.

Furthermore, with the demand for thinner, lighter, more flexible, higher quality and higher definition display devices, the polarizing plates used there are also required to be thinner, lighter, more flexible and have higher performance. ing. However, these requirements are difficult to achieve by simply thinning the components of the polarizing plate such as the polarizing element, the adhesive layer, the adhesive layer, and the polarizing element protective film. Specifically, when the constituent elements of the polarizing plate are made thin, the polarizing element is easily torn in the stretching direction, the polarizing element and the polarizing element protective film are deteriorated by the components of the pressure-sensitive adhesive or the adhesive, and the polarizing plate is curved. There was a tendency that the handleability at the time and when the polarizing plate was reworked was poor, and the tear strength was low and the peelability was poor. Under these circumstances, there is a demand for a polarizing plate that is thin and lightweight but has better durability than the current state.

However, depending on the type of material, sufficient durability may not be obtained depending on the usage environment (humidity, temperature, ultraviolet rays, etc.) and the usage mode (adhesive used for bonding, bending use, etc.). For example, if the usage environment or usage pattern is harsh, or if the usage environment or usage pattern fluctuates, the heat resistance, moisture resistance, light resistance, solvent resistance, diffraction resistance, and tear resistance of the polarizing plate may be affected. Properties such as properties and dimensional stability were not always sufficient.

In addition, it may be difficult to cut the polarizing element protective film with a laser beam. If it was forcibly cut with a laser beam, cutting residue might be mixed in the polarizing plate. In addition, the cut surface of the polarizing element protective film may be raised, and the polarizing element protective film layer may be lifted in the polarizing plate manufactured in this manner, resulting in a decrease in moisture resistance. Therefore, there is a problem in the processability of the polarizing element protective film.
The present invention has been devised in view of the above problems, and is a display device including a polarizing element protective film that can be cut by a laser beam and a polarizing plate having excellent durability against a usage environment and a usage pattern. The purpose is to provide.

As a result of diligent studies to solve the above problems, the present inventor has found that by providing a base material containing a laser absorber on the polarizing element protective film, the polarizing element protective film can be cut by laser light. , The present invention has been completed.
That is, the present invention includes the following.

[1] A display device including a polarizing element protective film, a polarizing element, a retardation film, and a display element in this order.
The polarizing element protective film contains a base material containing a laser absorber and capable of functioning as a λ / 4 plate.
A display device in which the in-plane retardation Re (550) of the retardation film at a wavelength of 550 nm is 90 nm to 150 nm.
[2] The substrate has a first substrate layer having an in-plane retardation Re (550) at a wavelength of 550 nm or less of 10 nm or less, and a second substrate having an in-plane retardation Re (550) at a wavelength of 550 nm of 90 nm to 150 nm. A base material layer and a conductive layer formed on at least one surface of the first base material layer are included.
The display device according to [1], wherein the laser absorber is contained in one or both of the first base material layer and the second base material layer.
[3] The base material is formed on at least one surface of the first base material layer that can function as a λ / 4 plate, the second base material layer that can function as a λ / 2 plate, and the first base material layer. It also contains a conductive layer and can function as a wideband λ / 4 plate.
The display device according to [1], wherein the laser absorber is contained in one or both of the first base material layer and the second base material layer.
[4] The display device according to [3], wherein the second base material layer is formed of a cured product of a liquid crystal composition containing a liquid crystal compound.
[5] One or both of the first base material layer and the second base material layer
With the first outer layer,
With the second outer layer,
The display device according to any one of [2] to [4], comprising the first outer layer and the intermediate layer provided between the second outer layers.
[6] The display device according to [5], wherein the intermediate layer contains an ultraviolet absorber.
[7] The first outer layer is formed of a first outer resin having _{a glass transition temperature Tg O1.}
The second outer layer is formed of a second outer resin having a glass transition temperature of Tg _O2.
The intermediate layer is formed of an intermediate resin having a glass transition temperature Tg _C.
The glass transition temperature Tg _O1 of the first outer resin is lower than the glass transition temperature Tg _{C of the intermediate resin.}
The display device according to [5] or [6], wherein the glass transition temperature Tg _O2 of the second outer resin is lower than the glass transition temperature Tg _{C of the intermediate resin.}
[8] The difference Tg _{C −} Tg _O1 between the glass transition temperature Tg _O1 of the first outer resin and the glass transition temperature Tg _C of the intermediate resin is 30 ° C. or higher.
The display device according to [7], wherein the difference Tg _{C −} Tg _O2 between the glass transition temperature Tg _O2 of the second outer resin and the glass transition temperature Tg _{C of the intermediate resin is 30 ° C. or higher.}
[9] The display device according to any one of [2] to [8], wherein the thickness of one or both of the first base material layer and the second base material layer is 10 μm to 60 μm.
[10] The display device according to any one of [1] to [9], wherein the slow axis of the base material and the transmission axis of the substituent intersect.
[11] The display device according to [10], wherein the crossing angle between the slow axis of the base material and the transmission axis of the polarizing element is 45 ° ± 5 °.
[12] The display device according to any one of [1] to [11], wherein the base material contains a polymer having crystallinity.
[13] The display device according to any one of claims [1] to [12], wherein the base material and the retardation film each contain an alicyclic structure-containing polymer.
[14] The display device according to any one of [1] to [13], wherein the base material and the retardation film each include a stretched film.
[15] The retardation film is formed of a cured product of a liquid crystal composition containing a liquid crystal compound.
The in-plane retardation Re (450) of the retardation film at a wavelength of 450 nm and the in-plane retardation Re (550) of the retardation film at a wavelength of 550 nm are Re (450) / Re (550) <1.0. The display device according to any one of [1] to [12], which satisfies the above conditions.
[16] The display device according to any one of [1] to [15], wherein the display element is a liquid crystal cell.
[17] The display device according to any one of [1] to [15], wherein the display element is an organic electroluminescence element.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a display device provided with a polarizing element protective film that can be cut by a laser beam and provided with a polarizing plate having excellent durability against a usage environment and a usage mode.

FIG. 1 is a cross-sectional view schematically showing a display device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of a resin layer that can be contained in a base material. FIG. 3 is a cross-sectional view schematically showing a base material as an example. FIG. 4 is a cross-sectional view schematically showing a base material as an example. FIG. 5 is a cross-sectional view schematically showing an example of a liquid crystal display device as a display device according to an embodiment of the present invention. FIG. 6 is a cross-sectional view schematically showing an example of an organic EL display device as a display device according to another embodiment of the present invention. FIG. 7 is a cross-sectional view schematically showing an example of an organic EL display device as a display device according to still another embodiment of the present invention. FIG. 8 is a cross-sectional view schematically showing an example of an organic EL display device as a display device according to still another embodiment of the present invention. FIG. 9 is a cross-sectional view schematically showing an example of an organic EL display device as a display device according to still another embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and may be arbitrarily modified and carried out without departing from the scope of claims of the present invention and the equivalent scope thereof.

In the following description, "ultraviolet rays" refer to light having a wavelength of 10 nm to 400 nm unless otherwise specified.

In the following description, the "long" shape means a shape having a length of 5 times or more, preferably 10 times or more, and specifically a roll. The shape of a film that has a length that allows it to be rolled up and stored or transported. The upper limit of the length of the long shape is not particularly limited, and may be, for example, 100,000 times or less with respect to the width.

In the following description, the in-plane retardation Re of the film and the layer is a value represented by Re = (nx-ny) × d unless otherwise specified. Further, the retardation Rth in the thickness direction of the film and the layer is a value represented by Rth = {(nx + ny) /2-nz} × d unless otherwise specified. Here, nx represents the refractive index in the direction perpendicular to the thickness direction of the film and the layer (in-plane direction) and in the direction giving the maximum refractive index. ny represents the refractive index of the film and the layer in the in-plane direction and orthogonal to the direction of nx. nz represents the refractive index of the film and the layer in the thickness direction. d represents the thickness of the film and the layer. The measurement wavelength is 550 nm unless otherwise specified.

In the following description, the front direction of a certain surface means the normal direction of the surface, and specifically, the direction of the polar angle 0 ° and the azimuth angle 0 ° of the surface, unless otherwise specified.

In the following description, unless otherwise specified, the "forward wavelength dispersion characteristic" means that the in-plane retardations Re (450) and Re (550) at wavelengths of 450 nm and 550 nm have a relationship of Re (450)> Re (550). Means to meet.

In the following description, unless otherwise specified, the "reverse wavelength dispersion characteristic" means that the in-plane retardations Re (450) and Re (550) at wavelengths of 450 nm and 550 nm have a relationship of Re (450) <Re (550). Means to meet.

In the following description, the slow axis of the film and the layer represents the slow axis in the plane of the film and the layer unless otherwise specified.

In the following description, the angle formed by the optical axes (polarization absorption axis, polarization transmission axis, slow phase axis, etc.) of each film or layer in a member having a plurality of films or layers is the above-mentioned film or layer unless otherwise specified. Represents the angle when viewed from the thickness direction.

In the following description, unless otherwise noted, the term "(meth) acryloyl group" includes acryloyl groups, methacryloyl groups and combinations thereof.

In the following description, the resin having a positive intrinsic birefringence value means a resin in which the refractive index in the stretching direction is larger than the refractive index in the direction orthogonal to the refractive index, unless otherwise specified. Further, the resin having a negative intrinsic birefringence value means a resin in which the refractive index in the stretching direction is smaller than the refractive index in the direction orthogonal to the refractive index unless otherwise specified. The intrinsic birefringence value can be calculated from the permittivity distribution.

In the following description, "polarizing plate", "λ / 2 plate" and "λ / 4 plate" are not only rigid members but also flexible like a resin film, unless otherwise specified. Also includes members to have.

[1. Overview]
FIG. 1 is a cross-sectional view schematically showing a display device 10 according to an embodiment of the present invention.
As shown in FIG. 1, the display device 10 according to the embodiment of the present invention includes a polarizing element protective film 110, a polarizing element 120, a retardation film 130, and a display element 140 in this order. Of these, the portion composed of the polarizing element protective film 110 and the polarizing element 120 functions as a polarizing plate.

The polarizing element protective film 110 includes a base material 111 capable of absorbing laser light. The base material 111 can absorb the laser light at the portion irradiated with the laser light and sublimate the material of the base material 111 at that portion. Further, when the polarizing element protective film 110 contains an arbitrary element (not shown) other than the base material 111, when the laser beam is irradiated, the arbitrary element is heated by the material of the sublimated base material 111 and melted or sublimated. Can occur. Therefore, the polarizing element protective film 110 can be easily cut by the laser beam. Further, when the polarizing element protective film 110 is cut in a state of being bonded to the polarizing element 120 and the retardation film 130, the polarizing element protective film is usually generated by the heat generated by the base material 111 absorbing the laser beam. Not only the 110 but also the polarizing element 120 and the retardation film 130 can be easily cut.

As described above, the display device 10 can be manufactured through a step of cutting the polarizing element protective film 110 by a laser beam. By cutting the polarizing element protective film 110 with a laser beam, it is possible to suppress the generation of cutting residue and smooth the cut surface. This makes it possible to improve the display quality in the display device 10 provided with the polarizing element protective film 110.

In order to evaluate the ease of cutting of the polarizing element protective film 110 with laser light, the cut surface is observed, and the cut surface can be evaluated by the following evaluation method.
The polarizing element protective film 110 and the polarizing element 120 are removed from the display device as an integral laminate without separating them. This laminate is bonded to a glass plate (for example, 0.7 mm thick) via an adhesive. After that, the laser beam is irradiated from the polarizing element protective film side. The cut surface can be evaluated by observing the cut surface of the polarizing element protective film under a microscope while irradiating the laser beam in this way.

[2. Polarizer protective film]
In order to enable absorption of laser light, the substrate contained in the polarizing element protective film contains a laser absorber. Further, the polarizing element protective film may contain any layer in combination with the base material.

[2.1. Base material]
As the base material, a film that can be cut by laser light can be used. Examples of the film that can be cut by laser light include 1) a film containing a polymer having a high average absorbance of laser light, and 2) a film containing a polymer having a low average absorbance of laser light and a laser absorber. Can be mentioned. However, in general, a polymer having a high average absorbance of laser light tends to have polarity and high hygroscopicity. Therefore, as the base material, a film containing a polymer having a low average absorbance of laser light and a laser absorber is preferable.

The absorbance of the laser beam can be measured using the "ATR method". The "ATR method" is a method of obtaining an absorption spectrum on the surface of a measurement target by irradiating the measurement target with a laser beam having an arbitrary wavelength and measuring the light totally reflected by the surface of the measurement target. .. The absorbance of light having an arbitrary wavelength within the wavelength range of the irradiated laser light can be determined as the average absorbance by measuring the absorbance of the light having an arbitrary wavelength by using the ATR method and calculating the average value of the obtained absorbances.

[2.1.1. Laser absorber contained in the base material]
As the laser absorber, a compound capable of absorbing the laser beam used for cutting can be used. In general, industrially, infrared laser light is often used as laser light. Here, the infrared laser light means a laser light having a wavelength in the infrared range of 760 nm or more and less than 1 mm. Therefore, as the laser absorber, it is preferable to use a compound capable of absorbing infrared laser light. _{In particular, as the infrared laser light, CO 2} laser light having a wavelength in the range of 9 μm to 11 μm is widely used because there are few cracks and chips on the cut surface and workability is good. _{There are two} types of CO 2 laser light, one with a wavelength of 10.6 μm and the other with a wavelength of 9.4 μm. In the cutting process of the polarizing element protective film and the polarizing plate, the one with a wavelength of 9.4 μm may be used. Recommended. For example, when cutting using a laser wavelength of 9.4 μm as compared to cutting using a laser wavelength of 10.6 μm, melt may protrude or melt and deform on the cut end face of the polarizing plate. Since this can be suppressed, the cut end face becomes smooth. Therefore, as the laser absorber, it is preferable to use a compound capable of absorbing laser light having a wavelength in the range of 9 μm to 11 μm. In particular, it is preferable to use compounds having absorption maximums at 9.4 μm and 10.6 μm.

Preferred laser absorbers include ester compounds. Ester compounds are usually polar compounds and can effectively absorb laser light having a wavelength in the range of 9 μm to 11 μm. Examples of the ester compound include a phosphoric acid ester compound, a carboxylic acid ester compound, a phthalate ester compound, and an adipic acid ester compound. Of these, a carboxylic acid ester compound is preferable from the viewpoint of being able to absorb _{CO 2 laser light particularly efficiently.}

Among the above-mentioned ester compounds, those containing an aromatic ring in the molecule are preferable, and those in which an ester bond is bonded to the aromatic ring are particularly preferable. Such ester compounds can absorb laser light more efficiently. Therefore, among the above-mentioned ester compounds, aromatic carboxylic acid esters are preferable, and benzoic acid esters such as diethylene glycol dibenzoate and pentaerythritol tetrabenzoate are particularly preferable because they are excellent in absorption efficiency of laser light.
Examples of such ester compounds include those described in International Publication No. 2016/31776.

Further, the laser absorber is preferably one that can function as a plasticizer. In general, the plasticizer can easily penetrate between the polymer molecules in the resin. In particular, when a polar laser absorber is mixed with a substrate containing a polar polymer, it can be satisfactorily dispersed in a resin without forming a sea-island structure. Therefore, when the layer contained in the base material is formed of the resin, it is possible to suppress the local absorption of the laser light, so that it is possible to improve the ease of cutting the base material as a whole. Generally, when a polar substance and a non-polar substance are mixed, they are difficult to mix with each other, so that haze may occur as a whole base material.

As the laser absorber such as an ester compound, one type may be used alone, or two or more types may be used in any combination.

The molecular weight of the laser absorber is preferably 300 or more, more preferably 400 or more, particularly preferably 500 or more, preferably 2200 or less, more preferably 1800 or less, and particularly preferably 1400 or less. By setting the molecular weight of the laser absorber to be equal to or higher than the lower limit of the above range, bleed-out of the laser absorber can be suppressed. Further, by setting the value to the upper limit or less, the laser absorber can be made easier to function as a plasticizer, and the molecules of the laser absorber can be started to move faster after heat is applied, so that the polarizing element protective film can be cut. Can be facilitated.

The melting point of the laser absorber is preferably 20 ° C. or higher, more preferably 60 ° C. or higher, particularly preferably 100 ° C. or higher, preferably 180 ° C. or lower, more preferably 150 ° C. or lower, and particularly preferably 120 ° C. or lower. .. By setting the melting point of the laser absorber to be equal to or higher than the lower limit of the above range, bleed-out of the laser absorber can be suppressed. Further, by setting the value to the upper limit or less, the laser absorber can be made easier to function as a plasticizer, and the molecules of the laser absorber can be started to move faster after heat is applied, so that the polarizing element protective film can be cut. Can be facilitated.

The laser absorber may be uniformly contained in the thickness direction of the base material. For example, when the base material is a single-layer structure film containing only one layer, it is preferable that the base material uniformly contains the laser absorber. Further, when the base material is a film having a multi-layer structure including a plurality of layers, all the layers contained in the base material may contain a laser absorber.
Further, the laser absorber may be unevenly distributed in the thickness direction of the base material, and thus may be contained only in a part of the base material. For example, when the base material is a film having a multi-layer structure, only a part of the layers contained in the base material may contain a laser absorber.

The content of the laser absorber in the substrate can be arbitrarily set within a range in which the polarizing element protective film can be cut by the laser beam. Therefore, among the layers contained in the base material, the content of the laser absorber in the layer containing the laser absorber is preferably set appropriately within a range in which the polarizing element protective film can be cut by the laser beam. In particular, the content of the laser absorber in the base material is preferably set according to whether the polymer contained in the base material is non-polar or polar.

Specifically, when the polymer contained in the substrate is non-polar, the content of the laser absorber in the layer containing the laser absorber is preferably 0.1% by weight or more, more preferably 1% by weight or more. It is particularly preferably 2% by weight or more, preferably 10% by weight or less, more preferably 9% by weight or less, and particularly preferably 8% by weight or less. By setting the content of the laser absorber to the lower limit of the above range or more, it is possible to impart the property of being able to efficiently absorb the laser light to the base material without impairing the original optical characteristics and mechanical characteristics of the base material. Further, by setting the value to the upper limit or less, the haze of the base material can be lowered, so that the transparency of the polarizing element protective film can be improved. Further, when the polarizing element protective film is cut by laser light, it is possible to prevent the cross section of the cut polarizing element protective film from becoming locally hot and causing large deformation due to heat melting.

When the polymer contained in the base material is polar, the content of the laser absorber in the layer containing the laser absorber is higher than that in the case where the polymer contained in the base material is non-polar, although it depends on the mixing conditions. be able to. The laser absorber can impart the property of efficiently absorbing laser light to the base material. In addition, it is desirable not to add too much laser absorber from the viewpoint of making it difficult to impair the original characteristics of the base material (for example, in-plane retardation and dimensional stability).

The dimensional stability of the film can be evaluated by the following evaluation method.
A film cut into 150 mm × 150 mm is used as a test piece, and the dimensions of the long film in the MD direction (flow direction) and the TD direction (width direction) are measured. Then, the film is placed horizontally on a talc bath in a gear oven kept at 150 ° C., and the amount of deformation in the MD direction and the TD direction after heating for 30 minutes is measured. Dimensional stability can be evaluated by this amount of deformation.

[2.1.2. Polymers that can be contained in the substrate]
The substrate usually contains a polymer in combination with the laser absorbers described above. Specifically, the substrate is usually a film with one or more resin layers containing a polymer, and some or all of the above resin layers contain a laser absorber. At this time, the substrate preferably contains a polymer having crystallinity from the viewpoint of enhancing solvent resistance, diffraction resistance and tear strength. In particular, when a crystalline polymer film and an amorphous polymer film are cut with laser light of the same wavelength and the same output, the crystalline polymer film curls. Is unlikely to occur. Therefore, from this viewpoint as well, a polymer having crystallinity is preferable. Here, the polymer having crystallinity means a polymer having a melting point Mp. The polymer having a melting point Mp means a polymer whose melting point Mp can be observed with a differential scanning calorimeter (DSC).

Further, the substrate preferably contains a non-polar alicyclic structure-containing polymer as the polymer from the viewpoints of low hygroscopicity and low water vapor permeability. Therefore, the base material is preferably a film having a single-layer structure or a multi-layer structure including a resin layer containing an alicyclic structure-containing polymer.

The alicyclic structure-containing polymer is a polymer having an alicyclic structure in a repeating unit. Since the alicyclic structure-containing polymer is excellent in mechanical strength, the impact strength of the polarizing element protective film can be effectively increased. Further, since the alicyclic structure-containing polymer has low hygroscopicity, the water vapor transmittance of the polarizing element protective film can be effectively reduced. Further, the alicyclic structure-containing polymer is usually excellent in transparency, dimensional stability and light weight.

Examples of the alicyclic structure-containing polymer include a polymer obtained by a polymerization reaction using a cyclic olefin as a monomer or a hydrogenated product thereof. Further, as the alicyclic structure-containing polymer, either a polymer having an alicyclic structure in the main chain or a polymer having an alicyclic structure in the side chain can be used. Examples of the alicyclic structure include a cycloalkane structure and a cycloalkene structure, but the cycloalkane structure is preferable from the viewpoint of thermal stability and the like.

The number of carbon atoms contained in one alicyclic structure is preferably 4 or more, more preferably 5 or more, more preferably 6 or more, preferably 30 or less, and more preferably 20 or less. Particularly preferably, the number is 15 or less. When the number of carbon atoms contained in one alicyclic structure is within the above range, mechanical strength, heat resistance, and moldability are highly balanced.

The proportion of the repeating unit having an alicyclic structure in the alicyclic structure-containing polymer is preferably 30% by weight or more, more preferably 50% by weight or more, still more preferably 70% by weight or more, and particularly preferably 90% by weight. That is all. The heat resistance can be improved by increasing the ratio of the repeating unit having an alicyclic structure as described above.
Further, in the alicyclic structure-containing polymer, the balance other than the structural unit having the alicyclic structure is not particularly limited and may be appropriately selected depending on the purpose of use.

As the alicyclic structure-containing polymer, either one having crystallinity or one having no crystallinity may be used, or both may be used in combination. By using a crystalline alicyclic structure-containing polymer, the impact strength, solvent resistance, diffraction resistance, and tear strength of the polarizing element protective film can be particularly enhanced. Further, by using the alicyclic structure-containing polymer having no crystallinity, the production cost of the polarizing element protective film can be reduced.

Examples of the alicyclic structure-containing polymer having crystallinity include the following polymers (α) to polymers (δ). Among these, the polymer (β) is preferable as the alicyclic structure-containing polymer having crystallinity because it is easy to obtain a polarizing element protective film having excellent heat resistance.
Polymer (α): A ring-opening polymer of a cyclic olefin monomer having crystallinity.
Polymer (β): A hydrogenated product of the polymer (α), which has crystallinity.
Polymer (γ): An addition polymer of a cyclic olefin monomer having crystallinity.
Polymer (δ): A hydrogenated product of the polymer (γ), which has crystallinity.

Specifically, as the alicyclic structure-containing polymer having crystallinity, a ring-opening polymer of dicyclopentadiene having crystallinity and a hydrogenated product of the ring-opening polymer of dicyclopentadiene. The crystallinity is more preferable, and the hydrogenated additive of the ring-opening polymer of dicyclopentadiene, which has crystallinity, is particularly preferable. Here, in the open-ring polymer of dicyclopentadiene, the ratio of the structural unit derived from dicyclopentadiene to all the structural units is usually 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more. More preferably, it refers to a polymer of 100% by weight.

The alicyclic structure-containing polymer having crystallinity does not have to be crystallized before the polarizing element protective film is produced. However, after the polarizing element protective film is produced, the crystalline alicyclic structure-containing polymer contained in the substrate can usually have a high crystallinity by being crystallized. .. The specific range of crystallinity can be appropriately selected depending on the desired performance, but is preferably 10% or more, more preferably 15% or more. By setting the crystallinity of the alicyclic structure-containing polymer contained in the substrate to be equal to or higher than the lower limit of the above range, high heat resistance and solvent resistance can be imparted to the polarizing element protective film. The crystallinity can be measured by X-ray diffraction.

The heat resistance of the polarizing element protective film can be evaluated by the heat resistant temperature. The heat resistant temperature of the polarizing element protective film is usually 160 ° C. or higher, preferably 180 ° C. or higher, and more preferably 200 ° C. or higher. Since the higher the heat resistant temperature is, the more preferable it is, there is no limit to the upper limit of the heat resistant temperature, but in the case of a crystalline polymer, the melting point is Tm or less.

The heat resistant temperature of the film can be evaluated by the following evaluation method.
The film as a sample is left to stand for 10 minutes in an atmosphere of a certain temperature Tx without applying tension. After that, the surface condition of the film is visually confirmed. When unevenness cannot be confirmed in the shape of the surface of the film, it can be seen that the heat resistant temperature of the film is equal to or higher than the above temperature Tx.

The solvent resistance of the film can be evaluated by the following evaluation method.
A film (50 mm × 10 mm sample) as a sample is cut out, and 1 ml of a predetermined solvent is applied. One minute after application, the presence or absence of a change in the appearance of the film can be observed to evaluate the solvent resistance.

As the solvent to which the polarizing element protective film has resistance, the solvent used for the pressure-sensitive adhesive or the adhesive can be used. Specific examples of this solvent include aliphatic hydrocarbons such as hexane, cyclohexane and octane; aromatic hydrocarbons such as toluene and xylene; alcohols such as ethanol, 1-propanol, isopropanol, 1-butanol and cyclohexanol; methyl ethyl ketone. , Methylisobutylketones, ketones such as cyclohexanone; esters such as ethyl acetate, butylacetate, isobutylacetate; monocyclics such as limonene.

Generally, when a polarizing plate is manufactured, the polarizing element protective film and the polarizing element are bonded to each other with a pressure-sensitive adhesive or an adhesive containing a solvent. At this time, if the polarizing element protective film does not have resistance to the solvent, the quality of the polarizing plate may be deteriorated, and as a result, the display quality of the display device may be deteriorated. However, if a crystalline alicyclic structure-containing polymer is used, a polarizing element protective film having excellent solvent resistance can be obtained, so that the above-mentioned deterioration in quality can be suppressed.
Whether or not the polarizing plate obtained by bonding the polarizing element protective film and the polarizing element via an adhesive or an adhesive has deteriorated in quality is determined by arranging the two polarizing plates on a polarizing microscope. , It can be evaluated by the clarity of black and white and the presence or absence of light leakage when one of the polarizing plates is rotated.

The melting point Mp of the crystalline alicyclic structure-containing polymer is preferably 200 ° C. or higher, more preferably 230 ° C. or higher, and preferably 290 ° C. or lower. By using such a crystalline alicyclic structure-containing polymer having a melting point Mp, it is possible to obtain a polarizing element protective film having a better balance between moldability and heat resistance.

The crystalline alicyclic structure-containing polymer has excellent folding resistance. Therefore, the polarizing element protective film is preferably excellent in folding resistance. Specifically, the folding resistance of the polarizing element protective film can be expressed by the folding resistance. The folding resistance of the polarizing element protective film provided with the substrate containing the alicyclic structure-containing polymer having crystallinity is usually 2000 times or more, preferably 2200 times or more, and more preferably 2400 times or more. Since the higher the folding resistance is, the more preferable it is, there is no limit to the upper limit of the folding resistance, but the folding resistance is usually 100,000 times or less.

The fold resistance can be measured by the following method by the MIT fold resistance test based on JIS P8115 "Paper and Paperboard-Fold Strength Test Method-MIT Test Machine Method".
A test piece having a width of 15 mm ± 0.1 mm and a length of about 110 mm is cut out from the film as a sample. At this time, the test piece is prepared so that the direction in which the film is stretched more strongly is parallel to the side of about 110 mm of the test piece. Then, using a MIT folding resistance tester (“No. 307” manufactured by Yasuda Seiki Seisakusho), the load is 9.8 N, the curvature of the bent portion is 0.38 ± 0.02 mm, the bending angle is 135 ° ± 2 °, and the bending speed. Bend the test piece so that a crease appears in the width direction of the test piece under the condition of 175 times / minute. This bending is continued, and the number of reciprocating bendings until the test piece breaks is measured.

The alicyclic structure-containing polymer having crystallinity as described above can be produced, for example, by the method described in International Publication No. 2016/067893.

On the other hand, the non-crystalline alicyclic structure-containing polymer is, for example, (1) norbornene polymer, (2) monocyclic cyclic olefin polymer, (3) cyclic conjugated diene polymer, (4) vinyl. Examples thereof include alicyclic hydrocarbon polymers and hydrogen additives thereof. Among these, the norbornene polymer and its hydrogenated product are more preferable from the viewpoint of transparency and moldability.

Examples of the norbornene polymer include a ring-opening polymer of a norbornene monomer, a ring-opening copolymer of a norbornene monomer and another monomer capable of ring-opening copolymerization, and hydrogenating agents thereof; an addition polymer of a norbornene monomer. Examples thereof include an addition copolymer of a norbornene monomer and another copolymerizable monomer. Among these, a ring-opening polymer hydrogenated additive of norbornene monomer is particularly preferable from the viewpoint of transparency.
The above alicyclic structure-containing polymer is selected from, for example, the polymers disclosed in JP-A-2002-321302.

As a resin containing an alicyclic structure-containing polymer having no crystallinity, various commercial products are commercially available, and among them, those having desired characteristics can be appropriately selected and used. Examples of such commercially available products are the product names "ZEONOR" (manufactured by Zeon Corporation), "Arton" (manufactured by JSR Corporation), "Apel" (manufactured by Mitsui Chemicals Co., Ltd.), and "TOPAS" (manufactured by Polyplastics Co., Ltd.). ) Product group.

Among the above-mentioned polymers, those having low polarity and having a low average absorbance of laser light by the polymer alone are preferable from the viewpoint of low hygroscopicity and low water vapor permeability. When a polymer having a low average absorbance of laser light is used as described above, the dimensional stability due to low hygroscopicity and the effect of combining the laser absorber can be particularly effectively utilized. Examples of the polymer having such a low average absorbance of laser light include "ZEONOR" manufactured by Zeon Corporation. The average absorbance of the cyclic olefin film made of "ZEONOR" was measured at a wavelength of 9.2 μm to 10.8 μm and found to be 0.05.

As the polymer, one type may be used alone, or two or more types may be used in combination at any ratio.

The glass transition temperature Tg of the polymer is preferably 80 ° C. or higher, more preferably 85 ° C. or higher, further preferably 100 ° C. or higher, preferably 250 ° C. or lower, and more preferably 170 ° C. or lower. A polymer having a glass transition temperature in such a range is less likely to be deformed and stressed when used at a high temperature, and is excellent in durability.

The weight average molecular weight (Mw) of the polymer is preferably 1,000 or more, more preferably 2,000 or more, still more preferably 10,000 or more, particularly preferably 25,000 or more, and preferably 1,000, It is 000 or less, more preferably 500,000 or less, still more preferably 100,000 or less, particularly preferably 80,000 or less, and particularly preferably 50,000 or less. A polymer having such a weight average molecular weight has an excellent balance between molding processability and heat resistance.

The molecular weight distribution (Mw / Mn) of the polymer is preferably 1.0 or more, more preferably 1.2 or more, particularly preferably 1.5 or more, preferably 10 or less, and more preferably 4.0 or less. More preferably, it is 3.5 or less. Here, Mn represents a number average molecular weight. A polymer having such a molecular weight distribution is excellent in molding processability.

The weight average molecular weight (Mw) and the number average molecular weight (Mn) can be measured as polyisoprene or polystyrene-equivalent weight average molecular weight by gel permeation chromatography using cyclohexane as a solvent. However, if the sample is insoluble in cyclohexane, toluene may be used as the solvent for gel permeation chromatography.

The content of the polymer in the substrate can be arbitrarily set according to the characteristics required for the polarizing element protective film. Therefore, among the layers contained in the substrate, the content of the polymer in the layer containing the polymer is preferably set appropriately according to the characteristics required for the polarizing element protective film. Specifically, the content of the polymer in the layer containing the polymer is preferably 50% by weight or more, more preferably 70% by weight or more, still more preferably 80% by weight or more, and particularly preferably 90% by weight. That is all.

[2.1.3. Resin layer that can be contained in the base material]
FIG. 2 is a cross-sectional view schematically showing an example of a resin layer that can be contained in a base material. As shown in FIG. 2, the resin layer 200 contained in the base material is preferably between the first outer layer 210, the second outer layer 220, and the first outer layer 210 and the second outer layer 220. Includes the provided intermediate layer 230. The resin layer 200 may include any layer other than the first outer layer 210, the intermediate layer 230, and the second outer layer 220, if necessary, but from the viewpoint of reducing the thickness, any layer may be provided. It is preferable that the layer has a three-layer structure. In such a resin layer 200, the first outer layer 210 and the intermediate layer 230 are usually in direct contact with each other without interposing another layer, and the intermediate layer 230 and the second outer layer 220 are in direct contact with each other. Is in direct contact with the plastic without going through other layers.

When the resin layer 200 including the first outer layer 210, the second outer layer 220, and the intermediate layer 230 contains a laser absorber as shown in FIG. 2, the laser absorber is usually contained in the intermediate layer 230. Since the laser absorber contained in the intermediate layer 230 is prevented from moving by the first outer layer 210 and the second outer layer 220, the resin layer 200 can suppress the bleed-out of the laser absorber.

The intermediate layer 230 is usually formed of a resin containing a polymer. Hereinafter, the resin forming the intermediate layer 230 is appropriately referred to as an "intermediate resin". As the polymer contained in the intermediate resin, it is preferable to use a thermoplastic polymer because the resin layer 200 can be easily produced. As such a polymer, an alicyclic structure-containing polymer is preferable because it is excellent in mechanical properties, heat resistance, transparency, low hygroscopicity, dimensional stability and light weight. In addition, one type of polymer may be used alone, or two or more types may be used in combination at any ratio.
The content of the polymer in the intermediate layer 230 is preferably 80.0% by weight or more, more preferably 82.0% by weight or more, particularly preferably 85.0% by weight or more, and preferably 97.0% by weight or less. , More preferably 96.0% by weight or less, and particularly preferably 95.0% by weight or less.

Further, the intermediate layer 230 may contain a laser absorber as described above. The amount of the laser absorber in the intermediate layer 230 can be appropriately set from the above-mentioned range as the range of the content of the laser absorber in the layer containing the laser absorber among the layers contained in the base material. Specifically, the amount of the laser absorber in the intermediate layer 230 is preferably 0.1% by weight or more, particularly preferably 1.0% by weight or more, preferably 10.0% by weight or less, and particularly preferably 8.0. It is less than% by weight.

The intermediate layer 230 may further contain any component in combination with the polymer and the laser absorber. Optional components include, for example, UV absorbers. Since the intermediate layer 230 containing the ultraviolet absorber can prevent the transmission of ultraviolet rays, it is possible to suppress the deterioration of the members included in the display device due to ultraviolet rays. Therefore, it is possible to suppress the coloring of the polarizing element by the ultraviolet rays contained in the external light, or to suppress the ultraviolet rays from the backlight to achieve a long life of the display element. Further, when the intermediate layer 230 contains an ultraviolet absorber, it is possible to suppress the bleed-out of the ultraviolet absorber, so that the concentration of the ultraviolet absorber in the intermediate layer 230 can be increased or the type of the ultraviolet absorber can be selected. You can widen the width. Therefore, even if the thickness of the resin layer 200 is thin, it is possible to enhance the ability to suppress the transmission of ultraviolet rays.

Further, by combining the laser absorber and the ultraviolet absorber, it is possible to suppress changes in characteristics such as the in-plane retardation of the resin and the cut-out dimensions, and to impart the property of efficiently absorbing the laser light to the base material. In addition, changes in the physical properties of the base material (in-plane retardation, dimensional change, internal haze, etc.) can be suppressed. Further, the film thickness unevenness can be reduced in the film forming process. In particular, when a polymer having crystallinity is combined with a laser absorber and an ultraviolet absorber, the above-mentioned effects such as suppression of changes in physical properties can be remarkably obtained. In general, even if a non-polar polymer having a low average absorbance of laser light (for example, an alicyclic structure-containing polymer) is mixed with a polar compound (for example, an ester compound), the dispersibility becomes insufficient, and the above-mentioned It was the technical recognition of those skilled in the art that physical properties tended to change easily. Therefore, the above-mentioned action is unexpected from the conventional common general technical knowledge. The reason why such an effect can be obtained by using a laser absorber and an ultraviolet absorber in combination is not well understood, but an appropriate laser absorber and an ultraviolet absorber are used in the intermediate layer 230 like a plasticizer. It is considered that it works and has an advantageous effect on the film-forming protease.

The total amount of the laser absorber and the ultraviolet absorber in the intermediate layer 230 is preferably 8.0% by weight or more, particularly preferably 10.0% by weight or more, preferably 20.0% by weight or less, and particularly preferably 16.0. It is less than% by weight. By keeping the total amount of the laser absorber and the ultraviolet absorber within the above range, changes in physical properties such as resin retardation are suppressed, leakage from the die during compound production is small, fish eye generation is suppressed, and resin burning is suppressed. can do.

As the ultraviolet absorber, a compound capable of absorbing ultraviolet rays can be used. Usually, an organic compound is used as such an ultraviolet absorber. Hereinafter, the ultraviolet absorber as an organic compound may be referred to as an "organic ultraviolet absorber". By using an organic ultraviolet absorber, it is usually possible to increase the light transmittance of the substrate at a visible wavelength and reduce the haze of the substrate. Therefore, the display performance of the display device can be improved.

Examples of the organic UV absorber include triazine-based UV absorbers, benzophenone-based UV absorbers, benzotriazole-based UV absorbers, acrylonitrile-based UV absorbers, salicylate-based UV absorbers, cyanoacrylate-based UV absorbers, and azomethine-based UV absorbers. Examples thereof include an absorbent, an indole-based ultraviolet absorber, a naphthalimide-based ultraviolet absorber, and a phthalocyanine-based ultraviolet absorber.

As the triazine-based ultraviolet absorber, for example, a compound having a 1,3,5-triazine ring is preferable. Specific examples of the triazine-based UV absorber include 2- (4,6-diphenyl-1,3,5-triazine-2-yl) -5-[(hexyl) oxy] -phenol, 2,4-bis. (2-Hydroxy-4-butoxyphenyl) -6- (2,4-dibutoxyphenyl) -1,3,5-triazine and the like can be mentioned. Examples of commercially available products of such triazine-based ultraviolet absorbers include "Chinubin 1577" manufactured by Ciba Specialty Chemicals, "LA-F70" and "LA-46" manufactured by ADEKA.

Examples of the benzotriazole-based ultraviolet absorber include 2,2'-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazole-2-yl) phenol], 2 -(3,5-di-tert-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (2H-benzotriazole-2-yl) -p-cresol, 2- (2H-benzotriazole-2) -Il) -4,6-bis (1-methyl-1-phenylethyl) phenol, 2-benzotriazole-2-yl-4,6-di-tert-butylphenol, 2- [5-chloro (2H)- Benzotriazole-2-yl] -4-methyl-6- (tert-butyl) phenol, 2- (2H-benzotriazole-2-yl) -4,6-di-tert-butylphenol, 2- (2H-benzo Triazole-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol, 2- (2H-benzotriazole-2-yl) -4-methyl-6- (3,4,5,5) 6-Tetrahydrophthalimidylmethyl) phenol, methyl 3- (3- (2H-benzotriazole-2-yl) -5-tert-butyl-4-hydroxyphenyl) propionate / polyethylene glycol 300 reaction product, 2- Examples thereof include (2H-benzotriazole-2-yl) -6- (linear and side chain dodecyl) -4-methylphenol. Examples of commercially available products of such triazole-based ultraviolet absorbers include "ADEKA STAB LA-31" manufactured by ADEKA and "TINUVIN 326" manufactured by Ciba Specialty Chemicals.

Examples of the azomethine-based ultraviolet absorber include the materials described in Japanese Patent No. 3366697, and examples of commercially available products include "BONASORB UA-3701" manufactured by Orient Chemical Co., Ltd.

Examples of the indole-based ultraviolet absorber include the materials described in Japanese Patent No. 2846091, and examples of commercially available products include "BONASORB UA-3911" and "BONASORB UA-3912" manufactured by Orient Chemical Co., Ltd. And so on.

Examples of the phthalocyanine-based ultraviolet absorber include the materials described in Japanese Patent No. 4403257 and Japanese Patent No. 3286905, and examples of commercially available products include "FDB001" and "FDB002" manufactured by Yamada Chemical Industry Co., Ltd. "And so on.

Particularly preferable UV absorbers are "LA-F70" manufactured by ASDEKA, which is a triazine-based UV absorber; Oriental Chemical Industry "UA-3701", which is an azomethine-based UV absorber; and a benzotriazole-based UV absorber. Examples thereof include "Tinuvin 326" manufactured by BASF and "LA-31" manufactured by ADEKA. Since these are particularly excellent in ultraviolet absorbing ability, it is possible to obtain a resin layer 200 having high ultraviolet blocking ability even if the amount is small.

As the ultraviolet absorber, one type may be used alone, or two or more types may be used in combination at any ratio.

The amount of the ultraviolet absorber in the intermediate layer 230 is preferably 3% by weight or more, more preferably 4% by weight or more, particularly preferably 5% by weight or more, preferably 20% by weight or less, and more preferably 18% by weight or less. Particularly preferably, it is 16% by weight or less. When the amount of the ultraviolet absorber is not less than the lower limit of the above range, the resin layer 200 can effectively suppress the transmission of ultraviolet rays. Further, when the amount of ultraviolet rays is not more than the upper limit of the above range, it is easy to increase the light transmittance of the resin layer 200 at the visible wavelength. Further, since the gelation of the resin due to the ultraviolet absorber can be suppressed during the production of the resin layer 200, it is easy to suppress the generation of fish eyes in the resin layer 200. Here, the fisheye refers to a foreign substance that may occur inside the layer.

Further, as another example of any component, for example, a colorant such as a pigment or a dye; a plasticizer; a fluorescent whitening agent; a dispersant; a lubricant; a heat stabilizer; a light stabilizer; an antistatic agent; an antioxidant; ; Examples include compounding agents such as surfactants. One of these may be used alone, or two or more of them may be used in combination at any ratio.

The glass transition temperature Tg _C of the intermediate resin is preferably 100 ° C. or higher, more preferably 120 ° C. or higher, particularly preferably 140 ° C. or higher, preferably 180 ° C. or lower, more preferably 170 ° C. or lower, and particularly preferably 165 ° C. It is as follows. By keeping the glass transition temperature Tg _C of the intermediate resin within the above range, changes in physical properties such as retardation of the intermediate layer 230 can be suppressed, and the film thickness can be stabilized during the production of the intermediate layer 230 to form a film with less film thickness unevenness. Can be made possible.

The thickness _{T 230} of the intermediate layer 230, the ratio _T 230 _{/ T 200} thickness _{T 230} of the intermediate layer 230 to the thickness _{T 200} of the resin layer 200 is preferably set to fall in a predetermined range. Specifically, the thickness ratio T ₂₃₀ / T ₂₀₀ is preferably 1/4 or more, more preferably 2/4 or more, preferably 80/82 or less, more preferably 79/82 or less, and particularly preferably. Is 78/82 or less. When the thickness ratio is equal to or higher than the lower limit, the resin layer 200 can effectively absorb the laser beam. Further, when the intermediate layer 230 contains an ultraviolet absorber, the transmission of ultraviolet rays can be effectively suppressed. Further, when the thickness ratio is not more than the upper limit value, the first outer layer 210 and the second outer layer 220 can be made thicker, so that the bleed-out of the laser absorber and the ultraviolet absorber can be stably suppressed, or the resin can be suppressed. The layer 200 can be easily manufactured.

The thickness of each layer in the resin layer including a plurality of layers can be measured by the following method. A sample piece is prepared by embedding the resin layer with epoxy resin. This sample piece is sliced to a thickness of 0.05 μm using a microtome. Then, by observing the cross section appeared by the slice with a microscope, the thickness of each layer contained in the resin layer can be measured.

The first outer layer 210 is usually formed of a resin containing a polymer. Hereinafter, the resin forming the first outer layer 210 is appropriately referred to as “first outer resin”. The first outer resin preferably has a lower content of the laser absorber than the intermediate resin contained in the intermediate layer 230, and more preferably does not contain the laser absorber. Further, the first outer resin preferably has a lower content of the ultraviolet absorber than the intermediate resin contained in the intermediate layer 230, and more preferably does not contain the ultraviolet absorber.

As the polymer contained in the first outer resin, it is preferable to use the same polymer as the polymer contained in the intermediate resin. This makes it easy to increase the adhesive strength between the intermediate layer 230 and the first outer layer 210 and suppress the reflection of light at the interface between the intermediate layer 230 and the first outer layer 210.
The amount of the polymer in the first outer layer 210 is preferably 90.0% by weight to 100% by weight, more preferably 95.0% by weight to 100% by weight.

The first outer resin may further contain any component in combination with the polymer. As the optional component, for example, the same component as mentioned as an arbitrary component that can be contained in the intermediate layer 230 can be mentioned.

The glass transition temperature Tg _O1 of the first outer resin is preferably lower than the glass transition temperature Tg _{C of the intermediate resin.} Further, the difference Tg _{C −} Tg _O1 between the glass transition temperature Tg _O1 of the first outer resin and the glass transition temperature Tg _C of the intermediate resin is preferably 30 ° C. or higher, more preferably 33 ° C. or higher, and particularly preferably 35 ° C. or higher. Is. When the difference in glass transition temperature Tg _{C −} Tg _O1 is within the above range, the amount of bleeding of the additive contained in the intermediate resin to the first outer resin can be suppressed. The upper limit of the difference in glass transition temperature Tg _{C −} Tg _O1 is preferably 55 ° C. or lower, more preferably 50 ° C. or lower, and particularly preferably 45 ° C. or lower. _{When the difference Tg C −} Tg _O1 of the glass transition temperature is not more than the above upper limit value, the adhesion between the first outer resin and the intermediate resin can be improved.

The method for adjusting the difference in glass transition temperature Tg _{C −} Tg _O1 under the above-mentioned conditions is not particularly limited. For example, when the intermediate resin contains a component other than the polymer (for example, a laser absorber, an arbitrary component), the glass transition temperature Tg _C of the intermediate resin can be adjusted by the type and amount of the component other than the polymer. _{Therefore, the difference Tg C −} Tg _O1 in the glass transition temperature may be adjusted by adjusting the type and amount of the components other than the polymer contained in the intermediate resin.

The thickness of the first outer layer 210 is preferably 3 μm or more, more preferably 5 μm or more, particularly preferably 7 μm or more, preferably 15 μm or less, more preferably 13 μm or less, and particularly preferably 10 μm or less. When the thickness of the first outer layer 210 is equal to or greater than the lower limit of the above range, bleed-out of the components contained in the intermediate layer 230 can be effectively suppressed. Further, when the thickness of the first outer layer 210 is not more than the upper limit of the above range, the resin layer 200 can be thinned.

The second outer layer 220 is usually formed of a resin containing a polymer. Hereinafter, the resin forming the second outer layer 220 is appropriately referred to as “second outer resin”. As the second outer resin, any resin selected from the range of resins described as the first outer resin can be used. Therefore, the component contained in the second outer resin can be selected and applied from the range described as the component contained in the first outer resin. Thereby, the same advantages as described in the description of the first outer layer 210 can be obtained.

The glass transition temperature Tg _O2 of the second outer resin is preferably lower than the glass transition temperature Tg _{C of the intermediate resin.} Further, the difference Tg _{C −} Tg _O2 between the glass transition temperature Tg _O2 of the second outer resin and the glass transition temperature Tg _C of the intermediate resin is preferably 30 ° C. or higher, more preferably 33 ° C. or higher, and particularly preferably 35 ° C. or higher. Is. As a result, the amount of bleeding of the additive contained in the intermediate resin to the second outer resin can be suppressed. The upper limit of the difference in glass transition temperature Tg _{C −} Tg _O2 is preferably 55 ° C. or lower, more preferably 50 ° C. or lower, and particularly preferably 45 ° C. or lower. _{When the difference Tg C −} Tg _O2 of the glass transition temperature is not more than the above upper limit value, the adhesion between the second outer resin and the intermediate resin can be improved.
The above-mentioned difference in glass transition temperature Tg _C- Tg _O2 can be adjusted in the same manner as, for example, the difference in glass transition temperature Tg _C- Tg _O1.

The second outer resin may be a resin different from the first outer resin, or may be the same resin as the first outer resin. Above all, it is preferable to use the same resin as the first outer resin and the second outer resin. By using the same resin as the first outer resin and the second outer resin, it is possible to suppress the manufacturing cost of the resin layer 200 and suppress the curl of the base material.

The thickness of the second outer layer 220 can be any thickness selected from the range described as the range of thickness of the first outer layer 210. Thereby, the same advantages as described in the description of the thickness of the first outer layer 210 can be obtained. Above all, in order to suppress the curl of the base material, it is preferable that the thickness of the second outer layer 220 is the same as that of the first outer layer 210.

Further, the resin layer contained in the base material is not limited to a multi-layer structure including two or more layers as in the resin layer 200 shown in FIG. 2, but is a single-layer structure including only one layer. You may. For example, the resin layer may be a single-layered layer containing a polymer and a laser absorber, and if necessary, a resin containing an arbitrary component such as an ultraviolet absorber. As a specific example, the above-mentioned intermediate layer itself may be used alone as a resin layer.

The amount of the volatile component contained in the resin layer is preferably 0.1% by weight or less, more preferably 0.05% by weight or less, still more preferably 0.02% by weight or less. When the amount of the volatile component is within the above range, the dimensional stability of the resin layer is improved, and the change over time of optical properties such as retardation can be reduced. Furthermore, deterioration of the polarizing element and the display device can be suppressed, and the display of the display device can be kept stable and good for a long period of time. Here, the volatile component is a substance having a molecular weight of 200 or less. Examples of the volatile component include residual monomers and solvents. The amount of volatile components can be quantified by analysis by gas chromatography as the total of substances having a molecular weight of 200 or less.

The saturated water absorption rate of the resin layer is preferably 0.05% or less, more preferably 0.03% or less, particularly preferably 0.01% or less, and ideally 0%. With such a low saturated water absorption rate of the resin layer, it is possible to suppress changes in the optical properties of the resin layer over time.

The saturated water absorption rate of the resin layer can be measured by the following procedure according to JIS K7209.
The resin layer is dried at 50 ° C. for 24 hours and allowed to cool in a desiccator. Next, the weight (M1) of the dried resin layer is measured.
This resin layer is immersed in water for 24 hours in a room having a temperature of 23 ° C. and a relative humidity of 50%, and the resin layer is saturated with water. Then, the resin layer is taken out from water, and the weight (M2) of the resin layer after immersion for 24 hours is measured.
From these measured values of weight, the saturated water absorption rate of the resin layer can be obtained by the following equation.
Saturated water absorption rate (%) = [(M2-M1) / M1] x 100 (%)

The thickness of the resin layer is preferably 15 μm or more, more preferably 20 μm or more, particularly preferably 25 μm or more, preferably 50 μm or less, more preferably 45 μm or less, and particularly preferably 40 μm or less.

There are no restrictions on the method of manufacturing the resin layer. For example, the resin layer 200 including the first outer layer 210, the intermediate layer 230, and the second outer layer 220 as shown in FIG. 2 is manufactured by a manufacturing method including a step of forming a resin for forming each layer into a film. , Can be manufactured. Examples of the resin molding method include a coextrusion method and a cocurrent spreading method. Among these molding methods, the coextrusion method is preferable because it has excellent production efficiency and it is difficult for volatile components to remain in the obtained resin layer.

Further, the resin layer contained in the base material may be a stretched film. Therefore, for example, the resin layer 200 provided with the first outer layer 210, the intermediate layer 230, and the second outer layer 220 as shown in FIG. 2 is formed into a film by the above-mentioned method and then subjected to a stretching treatment. It may be a plastic one. The stretched film is a film that has been stretched, and the polymer in the film is usually oriented by the stretching treatment. Therefore, since the stretched film can have optical properties according to the orientation of the polymer, the optical properties such as retardation can be easily adjusted. In addition, the stretched film can usually be thinned by stretching, a wide film can be obtained, and the mechanical strength can be improved. Therefore, by using a stretched film as the resin layer, a base material having suitable attributes can be easily obtained.

[2.1.4. Optically anisotropic layer that can be contained in the substrate]
The substrate may include an optically anisotropic layer formed of a cured product of a liquid crystal composition containing a liquid crystal compound. Here, the term "liquid crystal composition" includes not only a material containing two or more kinds of components but also a material containing only one kind of liquid crystal compound. Usually, the cured product of the liquid crystal composition has optical anisotropy depending on the liquid crystal compound, so that the optically anisotropic layer formed of the cured product has a predetermined in-plane retardation. In the following description, the optically anisotropic layer contained in the substrate may be referred to as a "first optically anisotropic layer" in order to distinguish it from the optically anisotropic layer that may be contained in the retardation film.

The liquid crystal compound is a compound capable of exhibiting a liquid crystal phase when blended in a liquid crystal composition and oriented. As such a liquid crystal compound, a polymerizable liquid crystal compound is usually used. Here, the polymerizable liquid crystal compound is a liquid crystal compound that can be polymerized in a liquid crystal composition in a state of exhibiting a liquid crystal phase and can become a polymer while maintaining the orientation of molecules in the liquid crystal phase.

Examples of the polymerizable liquid crystal compound include a liquid crystal compound having a polymerizable group, a compound capable of forming a side chain type liquid crystal polymer, and a disk-shaped liquid crystal compound. Among them, light such as visible light, ultraviolet rays, and infrared rays. A photopolymerizable compound that can be polymerized by irradiating with is preferable. Examples of the liquid crystal compound having a polymerizable group include JP-A-11-513360, JP-A-2002-030042, JP-A-2004-204190, JP-A-2005-263789, and JP-A-2007-119415. Examples thereof include rod-shaped liquid crystal compounds having a polymerizable group described in JP-A-2007-186430. Examples of the side-chain type liquid crystal polymer compound include the side-chain type liquid crystal polymer compound described in JP-A-2003-177242. Further, examples of preferable liquid crystal compounds by product name include "LC242" manufactured by BASF. Specific examples of the disk-shaped liquid crystal compound include JP-A-8-50206, Ref. (C. Destrade et al., Mol. Cryst. Liq. Cryst., Vol. 71, page 111 (1981); ed. , Quarterly Chemistry Review, No.22, Liquid Crystal Chemistry, Chapter 5, Chapter 10, Section 2 (1994); J. Zhang et al., J. Am. Chem. Soc., Vol. 116, page 2655 ( 1994)); J. Lehn et al., J. Chem. Soc., Chem. Communi., Page 1794 (1985). As the liquid crystal compound, one type may be used alone, or two or more types may be used in combination at any ratio.

The liquid crystal compound may be a reverse wavelength dispersible liquid crystal compound. Here, the reverse wavelength dispersible liquid crystal compound refers to a liquid crystal compound that exhibits reverse wavelength dispersion characteristics when homogenically oriented. Homogeneous alignment of a liquid crystal compound means that a layer containing the liquid crystal compound is formed, and the major axis direction of the mesogen of the molecule of the liquid crystal compound in the layer is oriented in one direction parallel to the plane of the layer. It means to let you. When the liquid crystal compound contains a plurality of types of mesogens having different orientation directions, the direction in which the longest type of mesogens is oriented is the orientation direction. Whether or not the liquid crystal compound is homogeneously oriented, and the orientation direction thereof are measured in the slow phase axial direction using a phase difference meter as represented by AxoScan (manufactured by Axometrics) and the incident angle in the slow phase axial direction. It can be confirmed by measuring the retardation distribution for each. By using the reverse wavelength dispersible liquid crystal compound as a part or all of the liquid crystal compound contained in the liquid crystal composition, the first optically anisotropic layer exhibiting the reverse wavelength dispersion characteristic can be easily obtained.

For example, a compound containing a main chain mesogen and a side chain mesogen bonded to the main chain mesogen in the molecule of the compound is preferably used as a liquid crystal compound, and more preferably used as a reverse wavelength dispersible liquid crystal compound. .. In the above-mentioned reverse wavelength dispersive liquid crystal compound containing the main chain mesogen and the side chain mesogen, the side chain mesogen may be oriented in a direction different from that of the main chain mesogen in the state where the reverse wavelength dispersive liquid crystal compound is oriented. In such a case, birefringence is expressed as the difference between the refractive index corresponding to the main chain mesogen and the refractive index corresponding to the side chain mesogen, and as a result, the inverse wavelength dispersible liquid crystal compound is homogenically oriented. It can show the reverse wavelength dispersion characteristic.

Examples of the polymerizable reverse wavelength dispersible liquid crystal compound include a compound represented by the following formula (I).

In the above formula (I), Y ^{1 to Y 8} are independently chemically single bonds, −O−, −S−, −OC (= O) −, −C (= O) −. O-, -O-C (= O) -O-, -NR ^1- C (= O)-, -C (= O) -NR ^1- , -O-C (= O) -NR ^1- , -NR ^1- C (= O) -O-, -NR ^1- C (= O) -NR ^1- , -O-NR ^1- , or -NR ^1- O-. Here, R ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

In the formula (I), G ¹ and G ² each represent a divalent aliphatic group having 1 to 20 carbon atoms, which may independently have a substituent. Further, the aliphatic group includes one or more -O-, -S-, -OC (= O)-, -C (= O) -O-, -O-C per aliphatic group. ^{(= O) -O -, -} NR 2 -C (= O) -, - C (= O) -NR 2 -, - NR 2 -, or, -C (= O) - is be interposed good. However, this excludes cases where two or more -O- or -S- are adjacent to each other. Here, R ² represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

In the formula (I), Z ¹ and Z ² each independently represent an alkenyl group having 2 to 10 carbon atoms which may be substituted with a halogen atom.

In the formula (I), A ^x has at least one aromatic ring selected from the group consisting of an aromatic hydrocarbon ring and aromatic heterocycle represents an organic group having 2 to 30 carbon atoms. The "aromatic ring" is a cyclic structure having aromaticity in a broad sense according to Huckel's rule, that is, a cyclic conjugated structure having (4n + 2) π electrons, and sulfur, oxygen, represented by thiophene, furan, benzothiazole and the like. It means a cyclic structure in which an isolated electron pair of a heteroatom such as nitrogen participates in a π-electron system and exhibits aromaticity.

In the formula (I), ^Ay is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, and an alkenyl group having 2 to 20 carbon atoms which may have a substituent. A cycloalkyl group having 3 to 12 carbon atoms which may have a substituent, an alkynyl group having 2 to 20 carbon atoms which may have a substituent, -C (= O) -R ³ , -SO ₂ -R ⁴ , -C (= S) NH-R ⁹ , or an organic group having 2 to 30 carbon atoms and having at least one aromatic ring selected from the group consisting of an aromatic hydrocarbon ring and an aromatic heterocycle. show. Here, R ³ has an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkenyl group having 2 to 20 carbon atoms which may have a substituent, and a substituent. It also represents a cycloalkyl group having 3 to 12 carbon atoms or an aromatic hydrocarbon ring group having 5 to 12 carbon atoms. R ⁴ is an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a phenyl group, or a 4-methylphenyl group. R ⁹ has an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkenyl group having 2 to 20 carbon atoms which may have a substituent, and a carbon which may have a substituent. It represents a cycloalkyl group having a number of 3 to 12, or an aromatic group having 5 to 20 carbon atoms which may have a substituent. Aromatic ring wherein A ^x and A ^y has may have a substituent. Further, the A ^x and A ^y may be combined to form a ring.

In the formula (I), A ¹ represents a trivalent aromatic group which may have a substituent.
In the formula (I), A ² and A ³ each independently represent a divalent alicyclic hydrocarbon group having 3 to 30 carbon atoms which may have a substituent.
In the formula (I), A ⁴ and A ⁵ are each independently, may have a substituent, a divalent aromatic group having 6 to 30 carbon atoms.
In the formula (I), Q ¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms which may have a substituent.
In the formula (I), m independently represents 0 or 1, respectively.

Examples of the liquid crystal compound represented by the formula (I) include the compounds described in International Publication No. 2014/069515, International Publication No. 2015/064511 and the like.

Further, the liquid crystal compound may be a forward wavelength dispersible liquid crystal compound. Here, the forward wavelength dispersible liquid crystal compound means a liquid crystal compound exhibiting forward wavelength dispersion characteristics when homogenically oriented. By using a forward wavelength dispersible liquid crystal compound as a part or all of the liquid crystal compound contained in the liquid crystal composition, a first optically anisotropic layer having a forward wavelength dispersion characteristic can be easily obtained.

Examples of the polymerizable forward wavelength dispersible liquid crystal compound include a compound represented by the following formula (II).
R ^3x- C ^3x- D ^3x- C ^5x- M ^x- C ^6x- D ^4x- C ^4x- R ^4x equation (II)

In formula (II), R ^3x and R ^4x each independently represent a reactive group. R ^3x and R ^4x are, for example, (meth) acryloyl group, epoxy group, thioepoxy group, oxetane group, thietanyl group, aziridinyl group, pyrrole group, fumarate group, cinnamoyl group, isocyanate group, isothiocyanate group, amino group, hydroxyl group. Examples thereof include a group, a carboxyl group, an alkoxysilyl group, an oxazoline group, a mercapto group, a vinyl group, an allyl group and the like.

In formula (II), D ^3x and D ^4x are independently single-bonded, linear or branched alkylene groups having 1 to 20 carbon atoms, and direct chains having 1 to 20 carbon atoms. Represents a group selected from the group consisting of chain or branched alkylene oxide groups.

In formula (II), C ^{3x to} C ^6x are independently single-bonded, -O-, -S-, -S-S-, -CO-, -CS-, -OCO-, -CH _{2. -, - OCH 2 -, -} CH = N-N = CH -, - NHCO -, - OCOO -, - CH 2 COO-, and represents a group selected from the group consisting of _-CH 2 OCO-.

In formula (II), M ^x represents a mesogen group. Preferred mesogenic groups M ^x may have a unsubstituted or substituted group, azomethines, azoxy compounds, phenyls, biphenyls, terphenyls, naphthalenes, anthracenes, benzoic acid esters, cyclohexanecarboxylic Two to four skeletons selected from the group consisting of acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidins, alkoxy-substituted phenylpyrimidins, phenyldioxans, trans, and alkenylcyclohexylbenzonitriles- O-, -S-, -S-S-, -CO-, -CS-, -OCO-, -CH _2- , -OCH _2- , -CH = N-N = CH-, -NHCO-,- OCOO _-, - CH 2 _COO-, and is formed are joined by a linking group of _-CH 2 OCO- or the like.

Examples of the substituent which the mesogenic group ^{M x} may have, for example, a halogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, a cyano group, a nitro ^{group, -O-R} 5x, -O- C (= O) -R ^5x , -C (= O) -O-R ^5x , -OC (= O) -OR ^5x , -NR ^5x- C (= O) -R ^5x , -C (= O) -NR ^5x R ^7x , or -OC (= O) -NR ^5x R ^7x can be mentioned. Here, R ^5x and R ^7x represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. When R ^5x and R ^7x are alkyl groups, the alkyl groups include -O-, -S-, -O-C (= O)-, -C (= O) -O-, -O-C. ^{(= O) -O -, -} NR 6x -C (= O) -, - C (= O) -NR 6x -, - NR 6x -, or -C (= O) - may be interposed (However, this does not apply when two or more -O- and -S- are adjacent to each other.) Here, R ^6x represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

Examples of the substituent in the above-mentioned "alkyl group having 1 to 10 carbon atoms which may have a substituent" include a halogen atom, a hydroxyl group, a carboxyl group, a cyano group, an amino group and 1 to 6 carbon atoms. Alkoxy group, alkoxyalkoxy group having 2 to 8 carbon atoms, alkoxyalkoxyalkoxy group having 3 to 15 carbon atoms, alkoxycarbonyl group having 2 to 7 carbon atoms, alkyl having 2 to 7 carbon atoms. Examples thereof include a carbonyloxy group and an alkoxycarbonyloxy group having 2 to 7 carbon atoms.

Examples of the liquid crystal compound represented by the formula (II) include rod-shaped liquid crystal compounds described in International Publication No. 2016/002765.

In addition, one type of liquid crystal compound may be used alone, or two or more types may be used in combination at any ratio.

The amount of the liquid crystal compound in the liquid crystal composition can be arbitrarily set within a range in which the desired first optically anisotropic layer can be obtained, and is preferably 1% by weight or more, more preferably 5% by weight or more, and particularly preferably 10% by weight. Further, it is preferably 100% by weight or less, more preferably 80% by weight or less, and particularly preferably 60% by weight or less.

The liquid crystal composition may contain any component in combination with the liquid crystal compound. Optional components include, for example, polymerization initiators, surfactants, solvents, metals, metal complexes, dyes, pigments, fluorescent materials, phosphorescent materials, leveling agents, thixo agents, gelling agents, polysaccharides, infrared absorbers, etc. Examples thereof include antioxidants, ion exchange resins, metal oxides such as titanium oxide, and the like. For any component, International Publication No. 2015/064511 may be referred to.

The first optically anisotropic layer is a layer formed of a cured product of a liquid crystal composition containing the above liquid crystal compound, and usually contains a cured liquid crystal molecule obtained from the liquid crystal compound. Here, the "cured liquid crystal molecule" means a molecule of the compound when the compound capable of exhibiting a liquid crystal phase is made into a solid while exhibiting the liquid crystal phase. The cured liquid crystal molecule contained in the first optically anisotropic layer is usually a polymer obtained by polymerizing a liquid crystal compound. Therefore, the first optically anisotropic layer usually contains a polymer obtained by polymerizing a liquid crystal compound, and is a layer of a resin that can contain an arbitrary component if necessary. Then, such a first optically anisotropic layer may have optical anisotropy according to the orientation state of the cured liquid crystal molecule. The optical anisotropy of the first optically anisotropy layer can be represented by in-plane retardation. The specific in-plane retardation of the first optically anisotropic layer can be set according to the in-plane retardation that the first optically anisotropic layer should have.

The thickness of the first optically anisotropic layer can be appropriately adjusted so that the optical properties such as retardation can be adjusted to a desired range, and is preferably 0.5 μm or more, more preferably 1.0 μm or more, and preferably 10 μm or less. , More preferably 7 μm or less, and particularly preferably 5 μm or less.

The first optically anisotropic layer is usually manufactured including a step of forming a layer of a liquid crystal composition on a support and a step of curing the layer of the liquid crystal composition to obtain a first optically anisotropic layer. It can be manufactured by the method.

In this manufacturing method, a support is prepared, and a layer of the liquid crystal composition is formed on the surface of the support. A resin film is usually used as the support. As the resin, a thermoplastic resin can be used. Among them, a resin containing an alicyclic structure-containing polymer and a cellulose ester resin are preferable from the viewpoints of transparency, low hygroscopicity, dimensional stability and light weight.

In order to promote the orientation of the liquid crystal compound in the layer of the liquid crystal composition, the surface of the support may be subjected to a treatment for imparting an orientation restricting force. Here, the orientation regulating force of a certain surface refers to the property of the surface that can orient the liquid crystal compound in the liquid crystal composition.

Examples of the treatment for imparting the orientation regulating force include a rubbing treatment, an alignment layer forming treatment, an ion beam alignment treatment, a stretching treatment, and the like, and among them, the stretching treatment is preferable. By applying the stretching treatment to the support under appropriate conditions, the molecules of the polymer contained in the support can be oriented. As a result, it is possible to impart an orientation restricting force for orienting the liquid crystal compound in the orientation direction of the polymer molecules contained in the support to the surface of the support.

It is preferable to extend the support by imparting anisotropy to the support so that the support can develop a slow phase axis. As a result, an orientation restricting force that orients the liquid crystal compound in a direction parallel to or perpendicular to the slow axis of the support is usually applied to the surface of the support. For example, when a resin having a positive intrinsic birefringence value is used as the material of the support, the slow axis parallel to the stretching direction is usually formed by orienting the polymer molecules contained in the support in the stretching direction. Since it is expressed, an orientation restricting force for orienting the liquid crystal compound in a direction parallel to the slow phase axis of the support is imparted to the surface of the support. Therefore, the stretching direction of the support can be set according to the desired orientation direction in which the liquid crystal compound is to be oriented.

The stretching ratio can be set so that the birefringence Δn of the support after stretching is in a desired range. The birefringence Δn of the support after stretching is preferably 0.000050 or more, more preferably 0.000070 or more, preferably 0.007500 or less, and more preferably 0.007000 or less. When the birefringence Δn of the support after stretching is at least the lower limit of the above range, a good orientation restricting force can be imparted to the surface of the support. The stretching can be performed using a stretching machine such as a tenter stretching machine.

As the support as described above, it is preferable to use a long film. By using a long film as the support, the productivity of the first optically anisotropic layer can be improved. At this time, the thickness of the support is preferably 1 μm or more, more preferably 5 μm or more, particularly preferably 30 μm or more, and preferably 1000 μm or less, from the viewpoint of facilitating productivity improvement, thinning and weight reduction. It is more preferably 300 μm or less, and particularly preferably 100 μm or less.

Further, as the support, the above-mentioned resin layer may be used. By using the resin layer to be contained in the base material as the support, it is not necessary to prepare the support separately from the material of the base material, so that the manufacturing cost of the base material can be reduced.

The formation of the layer of the liquid crystal composition is usually carried out by a coating method. Specifically, the liquid crystal composition is applied to the surface of the support to form a layer of the liquid crystal composition. Examples of the coating method include curtain coating method, extrusion coating method, roll coating method, spin coating method, dip coating method, bar coating method, spray coating method, slide coating method, print coating method, gravure coating method, and die coating. Methods, gap coating methods, and dipping methods can be mentioned. The thickness of the layer of the liquid crystal composition to be coated can be appropriately set according to the desired thickness required for the first optically anisotropic layer.

After forming the layer of the liquid crystal composition, a step of drying the layer of the liquid crystal composition may be performed, if necessary. Such drying can be achieved by a drying method such as natural drying, heat drying, vacuum drying, and vacuum heating drying. By such drying, the solvent can be removed from the layer of the liquid crystal composition.

Further, after forming the layer of the liquid crystal composition, a step of orienting the liquid crystal compound contained in the layer may be performed, if necessary. In this step, usually, the layer of the liquid crystal composition is subjected to an orientation treatment to orient the liquid crystal compound in a direction corresponding to the orientation restricting force of the surface of the support. The alignment treatment is usually performed by heating the layer of the liquid crystal composition to a predetermined alignment temperature. The conditions for this orientation treatment can be appropriately set according to the properties of the liquid crystal composition used. To give a specific example of the alignment treatment conditions, the treatment may be performed for 30 seconds to 5 minutes at a temperature condition of 50 ° C. to 160 ° C.

However, the orientation of the liquid crystal compound may be achieved immediately by coating the liquid crystal composition. Therefore, even when it is desired to orient the liquid crystal compound, the orientation treatment does not necessarily have to be applied to the layer of the liquid crystal composition.

If necessary, after drying the layer of the liquid crystal composition and orienting the liquid crystal compound, the layer of the liquid crystal composition is cured to obtain a first optically anisotropic layer. In this step, the liquid crystal compound is usually polymerized to cure the layer of the liquid crystal composition. As the method for polymerizing the liquid crystal compound, a method suitable for the properties of the components contained in the liquid crystal composition can be selected. Examples of the polymerization method include a method of irradiating with active energy rays and a thermal polymerization method. Above all, the method of irradiating with active energy rays is preferable because heating is not required and the polymerization reaction can proceed at room temperature. Here, the activated energy rays to be irradiated may include light such as visible light, ultraviolet rays, and infrared rays, and arbitrary energy rays such as electron beams.

Among them, a method of irradiating light such as ultraviolet rays is preferable because the operation is simple. The temperature at the time of irradiation with ultraviolet rays is preferably not more than the glass transition temperature of the support, preferably 150 ° C. or less, more preferably 100 ° C. or less, and particularly preferably 80 ° C. or less. The lower limit of the temperature at the time of irradiation with ultraviolet rays may be 15 ° C. or higher. The irradiation intensity of ultraviolet rays is preferably 0.1 mW / cm ² or more, more preferably 0.5 mW / cm ² or more, preferably 1000 mW / cm ² or less, more preferably 600 mW / cm ² or less.

The first optically anisotropic layer thus obtained may be peeled off from the support and used if necessary.

[2.1.5. Conductive layer that can be contained in the base material]
The base material may include a conductive layer in combination with the resin layer. The conductive layer is usually provided on one side or both sides of the resin layer contained in the base material. Since the resin layer is generally excellent in flexibility, it is possible to realize a touch panel in which input with a finger is smooth by using a base material having a conductive layer on the resin layer. In particular, in a substrate containing an alicyclic structure-containing polymer, the excellent heat resistance and low hygroscopicity of the alicyclic structure-containing polymer can be utilized, so that deformation such as curl occurs in a high temperature or high humidity environment. hard.

As the conductive layer, for example, a layer containing at least one conductive material selected from the group consisting of conductive metal oxides, conductive nanowires, metal meshes and conductive polymers can be used.

Examples of the conductive metal oxide include ITO (indium tin oxide), IZO (indium zinc oxide), ZnO (zinc oxide), IWO (indium tungsten oxide), ITOO (indium titanium oxide), and AZO (aluminum zinc oxide). , GZO (gallium zinc oxide), XZO (zinc-based special oxide), IGZO (indium gallium zinc oxide) and the like. Among these, ITO is particularly preferable from the viewpoint of light transmission and durability. One of these may be used alone, or two or more of them may be used in combination at any ratio.

The conductive layer containing a conductive metal oxide includes a vapor deposition method, a sputtering method, an ion plating method, an ion beam assist vapor deposition method, an arc discharge plasma vapor deposition method, a thermal CVD method, a plasma CVD method, a plating method, and a combination thereof. It can be formed by the film forming method of. Among these, the vapor deposition method and the sputtering method are preferable, and the sputtering method is particularly preferable. In the sputtering method, since the conductive layer having a uniform thickness can be formed, it is possible to suppress the generation of locally thin portions in the conductive layer.

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. In such conductive nanowires, the conductive nanowires form gaps to form a mesh, so that even a small amount of conductive nanowires can form a good electric conduction path, and electric resistance can be obtained. A small conductive layer can be realized. Further, since the conductive wire has a mesh shape to form an opening in the gap between the meshes, a conductive layer having high light transmittance can be obtained. Furthermore, by using a conductive layer containing conductive nanowires, it is usually possible to obtain a base material having excellent bending resistance.

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 to 100. It is 10,000. When conductive nanowires having a large aspect ratio are used in this way, the conductive nanowires can cross each other well, and a small amount of conductive nanowires can exhibit high conductivity. As a result, a base material having excellent transparency can be obtained. Here, the "thickness of the conductive nanowire" means the diameter of the conductive nanowire when the cross section is circular, the minor diameter of the conductive nanowire when it is elliptical, and when it is polygonal. Means the longest diagonal. The thickness and length of the conductive nanowires can be measured 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, still more preferably 10 nm to 100 nm, and particularly preferably 10 nm to 50 nm. This makes it possible to increase the transparency of the conductive layer.

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. This makes it possible to increase the conductivity of the conductive layer.

Examples of the conductive nanowires include metal nanowires made of metal, conductive nanowires containing carbon nanotubes, and the like.

The content of the conductive nanowires in the conductive layer is preferably 80% by weight to 100% by weight, more preferably 85% by weight to 99% by weight, based on the total weight of the conductive layer. This makes it possible to obtain a conductive layer having excellent conductivity and light transmission.

The conductive layer containing the conductive nanowires can be produced by applying and drying a conductive nanowire dispersion liquid obtained by dispersing the conductive nanowires in a solvent.

The metal mesh is a thin metal wire formed in a grid pattern. As the metal contained in the metal mesh, a metal having high conductivity is preferable. Examples of suitable metals include gold, platinum, silver and copper, with silver, copper and gold being preferred, and silver being more preferred. One of these metals may be used alone, or two or more of these metals may be used in combination at any ratio.

The conductive layer containing the metal mesh can be formed, for example, by applying a composition for forming a conductive layer containing a silver salt and forming fine metal lines in a predetermined lattice pattern by exposure treatment and development treatment. Further, the conductive layer containing the metal mesh can also be formed by printing a composition for forming a conductive layer containing metal fine particles on a predetermined pattern. For details of such a conductive layer and a method for forming the same, Japanese Patent Application Laid-Open No. 2012-18634 and Japanese Patent Application Laid-Open No. 2003-331654 can be referred to.

Examples of the conductive polymer include polythiophene-based polymers, polyacetylene-based polymers, polyparaphenylene-based polymers, polyaniline-based polymers, polyparaphenylene vinylene-based polymers, polypyrrole-based polymers, polyphenylene-based polymers, and polyester-based polymers modified with acrylic polymers. Examples include polymers. Of these, polythiophene-based polymers, polyacetylene-based polymers, polyparaphenylene-based polymers, polyaniline-based polymers, polyparaphenylene vinylene-based polymers, and polypyrrole-based polymers are preferable. Among them, a polythiophene-based polymer is particularly preferable. By using a polythiophene-based polymer, a conductive layer having excellent transparency and chemical stability can be obtained. Specific examples of the polythiophene-based polymer include polythiophene; poly (3-C _1-8 alkyl-thiophene) such as poly (3-hexylthiophene); poly (3,4-ethylenedioxythiophene), and poly (3,4). -Polypropylene dioxythiophene), poly [3,4- (1,2-cyclohexylene) dioxythiophene] and other polys (3,4- (cyclo) alkylenedioxythiophene); polythienylene binylene and the like. ..
In addition, one type of the above-mentioned conductive polymer may be used alone, or two or more types may be used in combination at any ratio.

The conductive layer containing the conductive polymer can be formed, for example, by applying a conductive composition containing the conductive polymer and drying it. For the conductive layer containing the conductive polymer, Japanese Patent Application Laid-Open No. 2011-175601 can be referred to.

The conductive layer may be formed on the entire surface of the base material in the in-plane direction, or may be patterned in a predetermined pattern. The shape of the pattern of the conductive layer is preferably a pattern that operates well as a touch panel (for example, a capacitive touch panel). Examples thereof include the patterns described in Japanese Patent Publication No. 2003-511799, and Japanese Patent Publication No. 2010-541109.

The surface resistance value of the conductive layer is preferably 2000 Ω / □ or less, more preferably 1500 Ω / □ or less, and particularly preferably 1000 Ω / □ or less. With such a low surface resistance value of the conductive layer, a high-performance touch panel can be realized by using a base material. There is no particular limitation on the lower limit of the surface resistance value of the conductive layer, but it is preferably 100 Ω / □ or more, more preferably 200 Ω / □ or more, and particularly preferably 300 Ω / □ or more because it is easy to manufacture.

The light transmittance in the wavelength range of 400 nm to 700 nm of the conductive layer is preferably 85% or more, more preferably 90% or more, still more preferably 95% or more.

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

[2.1.6. Optical properties and thickness of substrate]
The substrate described above can usually function as a λ / 4 plate. Here, the λ / 4 plate refers to a member having an in-plane retardation in a predetermined range at a wavelength of 550 nm. Specifically, the in-plane retardation of the λ / 4 plate at a wavelength of 550 nm is usually 110 nm or more, preferably 120 nm or more, more preferably 125 nm or more, and usually 165 nm or less, preferably 155 nm or less, more preferably 150 nm or less. Is. Therefore, the base material that can function as a λ / 4 plate is a base material having an in-plane retardation in the above range at a wavelength of 550 nm. A circular polarizing plate can be obtained by combining a base material that can function as a λ / 4 plate with a polarizing element.

The base material preferably has a high light transmittance at a visible wavelength from the viewpoint of improving the display quality of the display device. For example, the light transmittance of the substrate in the wavelength range of 400 nm to 700 nm is preferably 85% to 100%, more preferably 87% to 100%, and particularly preferably 90% to 100%.

The base material preferably has a small haze from the viewpoint of enhancing the image sharpness of the display device. The specific haze of the base material is preferably 1% or less, more preferably 0.8% or less, and particularly preferably 0.5% or less. Haze can be measured using a turbidity meter according to JIS K7361-1997.

When the base material is a single layer, the thickness of the base material is preferably 10 μm or more, more preferably 15 μm or more, particularly preferably 20 μm or more, preferably 100 μm or less, more preferably 80 μm or less, and particularly preferably 60 μm or less. Is. When the base material is a plurality of layers, the thickness of each layer is preferably 10 μm or more, more preferably 15 μm or more, particularly preferably 20 μm or more, preferably 100 μm or less, more preferably 80 μm or less, and particularly preferably 60 μm or less. ..

[2.1.7. First configuration example of the base material]
Hereinafter, a specific configuration example of the base material will be described with reference to the drawings.
FIG. 3 is a cross-sectional view schematically showing the base material 300 as an example. As shown in FIG. 3, the base material 300 according to this example has a first base material layer 310 having a small in-plane retardation Re (550) at a wavelength of 550 nm and a large in-plane retardation Re (550) at a wavelength of 550 nm. It includes a second base material layer 320 and a conductive layer 330 formed on at least one surface 310U of the first base material layer 310. The laser absorber is contained in one or both of the first base material layer 310 and the second base material layer 320. FIG. 3 shows an example in which the conductive layer 330 is formed on one surface 310U of the first base material layer 310, but the conductive layer 330 is formed on the other surface 310D of the first base material layer 310. It may be formed on both surfaces 310U and 310D of the first base material layer 310.

The first substrate layer 310 is preferably an optically isotropic layer. Therefore, it is preferable that the in-plane retardation Re (550) and the thickness direction retardation Rth (550) of the first base material layer 310 at a wavelength of 550 nm of the first base material layer are small. Specifically, the in-plane retardation Re (550) of the first substrate layer 310 at a wavelength of 550 nm is preferably 10 nm or less, more preferably 5 nm or less, particularly preferably 4 nm or less, and ideally 0 nm. be. The thickness direction retardation Rth (550) of the first substrate layer 310 at a wavelength of 550 nm is preferably 15 nm or less, more preferably 13 nm or less, and particularly preferably 10 nm or less. The lower limit is not particularly limited and is ideally 0 nm, but is usually 5 nm or more. Since the first base material layer 310 is optically isotropic in this way, it is possible to suppress coloring of the display screen and improve the viewing angle characteristics when used in a display device. The first base material layer 310 may have a single-layer structure or a multi-layer structure. Examples of the first base material layer 310 include an alicyclic structure-containing polymer film (for example, Zeonoa film (manufactured by Zeon Corporation)) and a triacetyl cellulose (TAC) film.

The in-plane retardation Re (550) of the second substrate layer 320 at a wavelength of 550 nm is preferably 90 nm or more, more preferably 100 nm or more, particularly preferably 110 nm or more, preferably 150 nm or less, and more preferably 145 nm. Below, it is particularly preferably 140 nm or less. Examples of the second base material layer include diagonally stretched films (Zeonoa film ZD series, manufactured by Zeon Corporation).
By combining the first base material layer 310 and the second base material layer 320 having such a retardation, the base material 300 that can function as a λ / 4 plate can be realized.

As a preferred embodiment of the base material 300, one or both of the first base material layer 310 and the second base material layer 320 are the first outer layer, the second outer layer, and the first outer layer and the first outer layer. It is a resin layer having a multi-layer structure including an intermediate layer provided between the two outer layers (see FIG. 2). In such a resin layer, the components contained in the intermediate layer are unlikely to cause bleed-out. Therefore, when the intermediate layer contains a component that easily causes bleed-out, the base material 300 can be manufactured while suppressing the contamination of the manufacturing equipment due to the bleed-out. Therefore, it is preferable that the laser absorber and the ultraviolet absorber as an arbitrary component are contained in the intermediate layer.

In the above-mentioned base material 300, the thickness of one or both of the first base material layer 310 and the second base material layer 320 is preferably 10 μm to 60 μm, more preferably 15 μm to 55 μm, and particularly preferably 20 μm to 50 μm. When the thickness of one or both of the first base material layer 310 and the second base material layer 320 falls within the above range, the self-supporting property of the polarizing element protective film itself can be maintained, and the rigidity of the polarizing element protective film can be maintained. Can be maintained.

[2.1.8. Second configuration example]
Hereinafter, another specific configuration example of the base material will be described with reference to the drawings.
FIG. 4 is a cross-sectional view schematically showing the base material 400 as an example. As shown in FIG. 4, the base material 400 according to this example includes a first base material layer 410 that can function as a λ / 4 plate, a second base material layer 420 that can function as a λ / 2 plate, and a first base material. It includes a conductive layer 430 formed on at least one surface 410U of the layer 410. The laser absorber is contained in one or both of the first base material layer 410 and the second base material layer 420. FIG. 4 shows an example in which the conductive layer 430 is formed on one surface 410U of the first base material layer 410, but the conductive layer 430 is formed on the other surface 410D of the first base material layer 410. It may be formed on both surfaces 410U and 410D of the first substrate layer 410.

The first base material layer 410 is a layer that can function as a λ / 4 plate. Therefore, the first substrate layer 410 has an in-plane retardation in a predetermined range at a wavelength of 550 nm. Specifically, the in-plane retardation of the first substrate layer 410 at a wavelength of 550 nm is usually 110 nm or more, preferably 120 nm or more, more preferably 125 nm or more, usually 165 nm or less, preferably 155 nm or less, more preferably. It is 150 nm or less.

The second base material layer 420 is a layer that can function as a λ / 2 plate. Here, the λ / 2 plate refers to a layer having an in-plane retardation in a predetermined range at a wavelength of 550 nm. Specifically, the in-plane retardation of the λ / 2 plate at a wavelength of 550 nm is usually 240 nm or more, preferably 250 nm or more, usually 300 nm or less, preferably 280 nm or less, and particularly preferably 265 nm or less. Therefore, the second base material layer 420 that can function as a λ / 2 plate is a layer having an in-plane retardation in the above range at a wavelength of 550 nm.

By including the first base material layer 410 that can function as a λ / 4 plate and the second base material layer 420 that can function as a λ / 2 plate in combination, the base material 400 can function as a wideband λ / 4 plate. Here, the wideband λ / 4 plate means a λ / 4 plate exhibiting reverse wavelength dispersion characteristics. Since the wideband λ / 4 board can function as a λ / 4 board in a wide wavelength range, a display device including a base material 400 that can function as a wideband λ / 4 board is particularly intended for an image observed from the front direction. It is possible to suppress coloring that does not occur. Further, by combining a polarizing element protective film containing a base material 400 that can function as a wideband λ / 4 plate with a polarizing element, a circular polarizing plate that can function in a wide wavelength range can be realized.

However, in order to enable the base material 400 to function as a broadband λ / 4 plate, the crossing angle formed by the slow phase axis of the first base material layer 410 and the slow phase axis of the second base material layer 420 is appropriate. It is preferable to adjust to the range.
Generally, a λ / 4 plate having a slow axis having an angle θ (λ / 4) with respect to a certain reference direction and a λ / having a slow axis having an angle θ (λ / 2) with respect to the reference direction. When the multi-layer film in which the two plates are combined satisfies the formula (X): "θ (λ / 4) = 2θ (λ / 2) + 45 °", the multi-layer film is the multi-layer film in a wide wavelength range. It is a wideband λ / 4 plate capable of imparting an in-plane retardation of approximately 1/4 wavelength of the wavelength of the light passing through the film in the front direction (see JP-A-2007-004120). Therefore, from the viewpoint of obtaining a base material 400 that can function as a wideband λ / 4 plate by combining the first base material layer 410 that can function as a λ / 4 plate and the second base material layer 420 that can function as a λ / 2 plate. It is represented by the above formula (X) between the slow axis of the first base material layer 410 that can function as a λ / 4 plate and the slow axis of the second base material layer 420 that can function as a λ / 2 plate. It is preferable to satisfy the relationship close to. From this point of view, the crossing angle formed by the slow axis of the first base material layer 410 that can function as a λ / 4 plate and the slow axis of the second base material layer 420 that can function as a λ / 2 plate is preferable. Is 55 ° or more, more preferably 57 ° or more, particularly preferably 59 ° or more, preferably 65 ° or less, more preferably 63 ° or less, and particularly preferably 61 ° or less.

As a preferred embodiment of the base material 400, the second base material layer 420 is preferably a first optically anisotropic layer formed of a cured product of a liquid crystal composition containing a liquid crystal compound. Usually, a cured product of a liquid crystal composition can increase durability, and even if it is thin, it is easy to obtain a large retardation. Therefore, by using the first optically anisotropic layer as the second base material layer 420, a thin base material layer 400 having particularly excellent heat resistance can be obtained.
When the first optically anisotropic layer is used as the second base material layer 420, a resin layer containing a laser absorber is usually used as the first base material layer 410.

Further, as another preferred embodiment of the base material 400, one or both of the first base material layer 410 and the second base material layer 420 may be the first outer layer, the second outer layer, and the first one. A resin layer having a multi-layer structure including an intermediate layer provided between the outer layer and the second outer layer is preferable (see FIG. 2). In such a resin layer, from the viewpoint of suppressing bleed-out, it is preferable that the laser absorber and the ultraviolet absorber as an arbitrary component are contained in the intermediate layer.

In the above-mentioned base material 400, the thickness of one or both of the first base material layer 410 and the second base material layer 420 is preferably 10 μm to 60 μm, as in the first configuration example of the base material.

[2.2. Any layer]
The polarizing element protective film may further contain any layer in combination with the substrate. Examples of the optional layer include an adhesive layer, an adhesive layer, a hard coat layer, an index matching layer, an easy adhesive layer, an antiglare layer, an antireflection layer and the like.

[2.3. Characteristics and thickness of polarizing element protective film]
The polarizing element protective film preferably has a high light transmittance at a visible wavelength from the viewpoint of improving the display quality of the display device. For example, the light transmittance of the polarizing element protective film in the wavelength range of 400 nm to 700 nm is preferably 85% to 100%, more preferably 87% to 100%, and particularly preferably 90% to 100%.

Further, in order to suppress deterioration of the polarizing element due to external light and ultraviolet rays from the backlight, the light transmittance at a wavelength of 380 nm is preferably 1% or less, more preferably 0.5% or less, and particularly preferably 0.05. % Or less. The light transmittance can be controlled by an ultraviolet absorber.

The polarizing element protective film preferably has a small haze from the viewpoint of enhancing the image sharpness of the display device. The haze of the polarizing element protective film is preferably 1% or less, more preferably 0.8% or less, and particularly preferably 0.5% or less.

The thickness of the polarizing element protective film is not particularly limited, but is preferably 10 μm or more, more preferably 15 μm or more, particularly preferably 20 μm or more, preferably 100 μm or less, more preferably 80 μm or less, and particularly preferably 60 μm or less. Is.

[3. Polarizer]
The polarizing element is an optical member having a polarization transmitting axis and a polarization absorbing axis. This polarizing element can absorb linearly polarized light having a vibration direction parallel to the polarization absorption axis and pass linearly polarized light having a vibration direction parallel to the polarization transmission axis. Here, the vibration direction of linearly polarized light means the vibration direction of an electric field of linearly polarized light.

Examples of the polarizing element include dyeing, stretching, and cross-linking a film of an appropriate vinyl alcohol-based polymer such as polyvinyl alcohol and partially formalized polyvinyl alcohol with a dichroic substance such as iodine and a dichroic dye. Films that have been subjected to the appropriate treatments in the appropriate order and method can be used. The linear polarizing element is preferably one having an excellent degree of polarization. The thickness of the linear polarizing element is generally, but is not limited to, 5 μm to 80 μm.

From the viewpoint of obtaining a circular polarizing plate by combining a polarizing element protective film containing a base material that can function as a λ / 4 plate and a polarizing element, the slow axis of the base material of the polarizing element protective film and the transmission axis of the polarizing element are It is preferable that they intersect. At this time, it is preferable that the crossing angle between the slow axis of the base material and the transmission axis of the substituent is within a predetermined range. The specific range of the intersection angle is preferably 45 ° ± 5 °, more preferably 45 ° ± 3 °, and particularly preferably 45 ° ± 1 °. When the crossing angle is adjusted to the above range, the linearly polarized light that has passed through the polarizing element and entered the polarizing element protective film can be converted into circularly polarized light by a base material that can function as a λ / 4 plate. By converting the linearly polarized light that has passed through the polarizing element and entered the polarizing element protective film into circularly polarized light, the display device with the polarizing element protective film placed on the visual side deteriorates the display quality even when viewed through polarized sunglasses. You can see the display device without.

[4. Phase difference film]
The retardation film is a film having an in-plane retardation Re (550) at a wavelength of 550 nm of 90 nm to 150 nm. More specifically, the in-plane retardation Re (550) of the retardation film at a wavelength of 550 nm is preferably 90 nm or more, more preferably 95 nm or more, particularly preferably 100 nm or more, preferably 150 nm or less, and more preferably 145 nm. Below, it is particularly preferably 140 nm or less. A retardation film having an in-plane retardation Re (550) in such a range can function as a λ / 4 plate. Therefore, a circularly polarizing plate can be obtained by combining a retardation film and a polarizing element.

From the viewpoint of obtaining a circularly polarizing plate by combining a retardation film and a polarizing element, it is preferable that the slow axis of the retardation film and the transmission axis of the polarizing element intersect with each other. At this time, it is preferable that the crossing angle between the slow axis of the retardation film and the transmission axis of the polarizing element is within a predetermined range. The specific range of the intersection angle is preferably 45 ° ± 5 °, more preferably 45 ° ± 3 °, and particularly preferably 45 ° ± 1 °. When the crossing angle is adjusted to the above range, the linearly polarized light that has passed through the polarizing element and entered the retardation film can be converted into circularly polarized light by the retardation film.

As the retardation film, for example, a film formed of a resin can be used. As the resin for forming the retardation film, a polymer and, if necessary, a resin containing an arbitrary component other than the polymer can be used. Therefore, as the retardation film, a film containing a polymer and, if necessary, an arbitrary component can be used. As this film, a single-layer structure film may be used, or a multi-layer structure film may be used.

As the polymer, for example, any polymer selected from the range described as the polymer that can be contained in the substrate can be used, and among them, the alicyclic structure-containing polymer is preferable. By using the retardation film containing the alicyclic structure-containing polymer, it is possible to obtain a display device having excellent durability by utilizing the excellent properties of the alicyclic structure-containing polymer.
The amount of the polymer in the retardation film is preferably 90.0% by weight to 100% by weight, more preferably 95.0% by weight to 100% by weight. By setting the amount of the polymer in the above range, the moisture resistance and mechanical strength of the retardation film can be effectively increased.
Moreover, as an arbitrary component, for example, the same component as mentioned as an arbitrary component which can be contained in a substrate can be mentioned.

The retardation film preferably includes a stretched film. This stretched film is a film obtained by subjecting a resin film to a stretching treatment, and the stretched film itself can usually be used as a retardation film. By using the stretched film, a retardation film can be easily obtained.

Further, as the retardation film, for example, an optically anisotropic layer formed of a cured product of a liquid crystal composition containing a liquid crystal compound may be used. In the following description, the optically anisotropic layer as the retardation film may be referred to as a "second optically anisotropic layer" in order to distinguish it from the first optically anisotropic layer that may be contained in the substrate. As the second optically anisotropic layer, a layer included in the range described as the first optically anisotropic layer can be arbitrarily used. Usually, according to a cured product of a liquid crystal composition, durability can be improved and a large retardation can be easily obtained even if it is thin. Therefore, by using a second optically anisotropic layer as a retardation film, a display device can be used. Achieves thinning.

When the retardation film is the second optically anisotropic layer, the in-plane retardation Re (450) of the retardation film at a wavelength of 450 nm and the in-plane retardation Re (550) of the retardation film at a wavelength of 550 nm are It is preferable to satisfy Re (450) / Re (550) <1.0. A retardation film having a retardation satisfying Re (450) / Re (550) <1.0 can function as a wideband λ / 4 plate. Therefore, it is possible to obtain a circularly polarizing plate that can function in a wide wavelength range by combining a retardation film and a polarizing element. For the retardation film having a retardation satisfying Re (450) / Re (550) <1.0, for example, by using a liquid crystal composition containing a reverse wavelength dispersion liquid crystal as the material of the second optically anisotropic layer. Obtainable.

The thickness of the retardation film can be appropriately adjusted so that the optical properties such as retardation can be adjusted to a desired range, and is preferably 1.0 μm or more, more preferably 3.0 μm or more, and particularly preferably 5.0 μm or more. It is preferably 100 μm or less, more preferably 80 μm or less, and particularly preferably 55 μm or less.

[5. Display element]
There are various display elements depending on the type of display device. Examples of typical display elements include liquid crystal cells and organic electroluminescence devices (hereinafter, may be appropriately referred to as "organic EL devices").

The liquid crystal cell has, for example, in-plane switching (IPS) mode, vertical alignment (VA) mode, multi-domain vertical alignment (MVA) mode, continuous spin wheel alignment (CPA) mode, hybrid alignment nematic (HAN) mode, twisted nematic. The liquid crystal cell of any mode such as (TN) mode, super twisted nematic (STN) mode, optical compensated bend (OCB) mode can be used. Such a liquid crystal cell is usually provided as a display element in a liquid crystal display device.

The organic EL element usually includes a transparent electrode layer, a light emitting layer, and an electrode layer in this order, and the light emitting layer can generate light by applying a voltage from the transparent electrode layer and the electrode layer. Examples of the materials constituting the organic light emitting layer include polyparaphenylene vinylene-based materials, polyfluorene-based materials, and polyvinylcarbazole-based materials. Further, the light emitting layer may have a laminate of a plurality of layers having different emission colors, or a mixed layer in which a layer of a certain dye is doped with different dyes. Further, the organic EL element may include functional layers such as a barrier layer, a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, an equipotential surface forming layer, and a charge generation layer. Such an organic EL element is usually provided as a display element in an organic EL display device.

[6. Any member]
If necessary, the display device may include any member other than the above-mentioned polarizing element protective film, polarizing element, retardation film, and display element.
Examples of the optional member include a protective film; an optical compensation film for a liquid crystal cell; an adhesive layer and an adhesive layer for adhering members to each other included in a display device.

[7. Production method]
The above-mentioned display device is usually a step of preparing a polarizing element protective film; a step of bonding a polarizing element protective film and a polarizing element directly or via an arbitrary layer; a polarizing element and a retardation film directly or By a manufacturing method including a step of bonding the retardation film and the display element directly or via an arbitrary layer; a step of cutting the polarizing element protective film with a laser beam; Can be manufactured.

In the above-mentioned manufacturing method, the order of each step is arbitrary. For example, after the step of cutting the polarizing element protective film alone, a step of bonding the polarizing element protective film and the polarizing element may be performed. Further, for example, after the step of bonding the polarizing element protective film and the polarizing element and the step of bonding the polarizing element and the retardation film, a step of cutting the polarizing element protective film at the same time as the decoder and the retardation film. May be done.

As described above, the display device can usually be manufactured by a manufacturing method including a step of cutting the polarizing element protective film by a laser beam. While some conventional polarizing element protective films do not absorb enough laser light to be cut, a polarizing element protective film having a substrate containing a laser absorber can be used alone or in a single state. It can be cut by laser light in a state of being bonded to other members such as a polarizing element and a retardation film. Therefore, it is possible to suppress the generation of cutting residue and smooth the cut surface, so that it is possible to obtain a display device having excellent display quality. Further, since the polarizing element protective film has heat resistance, the dimensional change is small even when the film is cut by a laser beam, and a display device having excellent display quality can be obtained. Further, since the polarizing element protective film has solvent resistance, deterioration of the polarizing element protective film is small even when the film is bonded via an adhesive, and a display device having excellent display quality can be obtained.

As the laser light, a laser light having a wavelength that can be absorbed by the laser absorber can be used. Among them, laser light having a wavelength in the infrared region is preferable because it is widely used as industrial equipment. Among them, laser light having a wavelength in the range of 9 μm to 12 μm is preferable because an output suitable for cutting the polarizing element protective film can be efficiently obtained and can be introduced at a relatively low cost. In particular, laser light having a wavelength of 9 μm to 11 μm is more preferable, and laser light having a wavelength of 9 μm or more and 9.5 μm or less is particularly preferable. Laser light having such a wavelength can be stably output when a carbon dioxide laser device is used as the laser device.

As the laser light, a Gaussian mode laser light may be used, or a laser light having a top hat-like energy distribution may be used. Above all, as the laser light, it is preferable to use a laser light showing a top hat-like energy distribution in at least one direction. By using a laser beam having a top hat-like energy distribution, the cut surface of the polarizing element protective film can usually be a steep surface close to perpendicular to the main surface of the polarizing element protective film. Further, when a laser beam showing a top hat-shaped energy distribution is used, it is usually possible to suppress the swelling of the resin of the film in the vicinity of the cut surface.

The laser light may be continuous laser light or pulsed laser light, but pulsed laser light is preferable from the viewpoint of suppressing heat generation and performing cutting processing.

At the time of cutting, the laser beam is usually irradiated so that the irradiation point of the laser beam scans the surface of the polarizing element protective film along a desired line. This makes it possible to cut the polarizing element protective film into the shape to be cut. At this time, in order to move the surface of the polarizing element protective film to the irradiation point of the laser light, the laser light irradiation device may be moved, the polarizing element protection film may be moved, and the irradiation device and the polarizing element protection may be moved. Both of the films may be moved.

[8. Specific Embodiment of the display device]
Hereinafter, a more specific embodiment of the display device will be described, but the structure of the display device is not limited to the following embodiments.

FIG. 5 is a cross-sectional view schematically showing an example of a liquid crystal display device 50 as a display device according to an embodiment of the present invention.
As shown in FIG. 5, the liquid crystal display device 50 includes a light source 510; a light source side polarizing element 520; a liquid crystal cell 530 as a display element; a retardation film 540; a visible side polarizing element 550; and a laser absorber and λ. A polarizing element protective film 570; including a base material 560 that can function as a / 4 plate is provided in this order. Further, in FIG. 5, the base material 560 is a second base material layer 561 as a first optically anisotropic layer formed of a cured product of the liquid crystal composition; a first outer layer 562, and an intermediate layer containing a laser absorber. An example is shown in which the first base material layer 565 having the 563 and the second outer layer 564 in this order; and the conductive layer 566; are provided in this order from the viewing side polarizing element 550 side, but the base material layer 560. The structure is not limited to this example.

In the liquid crystal display device 50, a polarizing element including a light source side polarizing element 520, a liquid crystal cell 530, a retardation film 540, a viewing side polarizing element 550, and a base material 560 that can function as a λ / 4 plate, which is emitted from a light source 510. The image is displayed by the light that has passed through the protective film 570. Since optical compensation is performed by the retardation film 540, a sufficiently wide viewing angle can be obtained with the liquid crystal display device 50. Further, the light for displaying an image is linearly polarized light when it passes through the viewing side polarizing element 550, but is converted into circularly polarized light by passing through the base material 560 of the polarizing element protective film 570. Therefore, in the liquid crystal display device 50, since the image is displayed by circularly polarized light, it is possible to visually recognize the image when viewed through polarized sunglasses.

Further, in the liquid crystal display device 50, the conductive layer 566 can function as a circuit member such as electrodes and wiring for a touch panel. Therefore, it is possible to realize a liquid crystal display device 50 provided with a touch panel. Here, the touch panel is provided on the display device so that the user can input information by touching a predetermined place while referring to the image displayed on the display surface of the display device as needed. It is an input device. Examples of the operation detection method of the touch panel include a resistance film method, an electromagnetic induction method, a capacitance method, and the like, and a capacitance type touch panel is particularly preferable. In the example shown in FIG. 5, since the conductive layer 566 is provided at a position outside (visual recognition side) of the viewing side polarizing element 550 of the liquid crystal display device 50, an out-cell type touch panel can be obtained.

In the liquid crystal display device 50 described above, the polarizing element protective film 570 has a base material 560 containing a laser absorber. Therefore, the liquid crystal display device 50 can be manufactured by a manufacturing method including a step of cutting the polarizing element protective film 570 with a laser beam. Therefore, when the polarizing element protective film 570 is cut, the generation of cutting residue can be suppressed and the cut surface can be smoothed, so that excellent display quality can be realized.

FIG. 6 is a cross-sectional view schematically showing an example of an organic EL display device 60 as a display device according to another embodiment of the present invention.
As shown in FIG. 6, the organic EL display device 60 is an organic EL element 610 as a display element; a retardation film 620 having a predetermined in-plane retardation and capable of functioning as a λ / 4 plate; , A polarizing element protective film 650 containing a base material 640 containing a laser absorber and capable of functioning as a λ / 4 plate; in this order. Further, in FIG. 6, the base material 640 includes a first outer layer 641, an intermediate layer 642 containing a laser absorber, and a second outer layer 643 in this order; a second base material layer 644; a first outer layer 645, laser absorption. An example is shown in which an intermediate layer 646 containing an agent, a first base material layer 648 having a second outer layer 647 in this order; and a conductive layer 649; are provided in this order from the polarizing element 630 side. The structure of layer 640 is not limited to this example.

In the organic EL display device 60, the light incident from the outside of the device is circularly polarized light when only a part of the linearly polarized light passes through the polarizing element 630 and passes through the retardation film 620. Circularly polarized light is reflected by a component that reflects light in the display device (a reflective electrode (not shown) in the organic EL element 610, etc.) and passes through the retardation film 620 again to obtain the incident linearly polarized light. It becomes linearly polarized light having a vibration direction orthogonal to the vibration direction and does not pass through the modulator 630. Thereby, the antireflection function is achieved (for the principle of antireflection in the organic EL display device, refer to Japanese Patent Application Laid-Open No. 9-127885).

Further, in the organic EL display device 60, the light emitting from the organic EL element 610 has passed through a polarizing element protective film 650 including a retardation film 620, a polarizing element 630, and a base material 640 that can function as a λ / 4 plate. The light displays the image. The light displaying the image is linearly polarized light when it passes through the polarizing element 630, but is converted into circularly polarized light by passing through the base material 640 of the polarizing element protective film 650. Therefore, in the organic EL display device 60, since the image is displayed by circularly polarized light, it is possible to visually recognize the image when viewed through polarized sunglasses.

Further, in the organic EL display device 60, the conductive layer 649 can function as a circuit member such as electrodes and wiring for a touch panel. Therefore, it is possible to realize an organic EL display device 60 provided with a touch panel.

In the above-mentioned organic EL display device 60, the polarizing element protective film 650 has a base material 640 containing a laser absorber. Therefore, the organic EL display device 60 can be manufactured by a manufacturing method including a step of cutting the polarizing element protective film 650 with a laser beam, and thus has excellent display quality as in the liquid crystal display device 50. It is possible to realize.

FIG. 7 is a cross-sectional view schematically showing an example of an organic EL display device 70 as a display device according to still another embodiment of the present invention.
As shown in FIG. 7, the organic EL display device 70 is provided in the same manner as the organic EL display device 60 shown in FIG. 6, except that the polarizing element protective film 700 is provided instead of the polarizing element protective film 650. .. Specifically, the organic EL display device 70 shown in FIG. 7 is an organic EL element 610 as a display element; a retardation film 620 having a predetermined in-plane retardation and capable of functioning as a λ / 4 plate; a polarizing element 630. And a polarizing element protective film 700 containing a base material 710 containing a laser absorber and capable of functioning as a λ / 4 plate; in this order.

Further, the base material 710 includes a first outer layer 721, an intermediate layer 722 containing a laser absorber, and a second outer layer 723 in this order; a second base material layer 720; a first base material layer 730 containing a laser absorber; Further, the conductive layer 740; is provided in this order from the polarizing element 630 side. The second base material layer 720 preferably has a large in-plane retardation Re (550) as described in the first configuration example of the base material, and among them, the second base material layer 720 is a λ / 4 plate. It is particularly preferable to have an in-plane retardation Re (550) capable of functioning as. Further, the first base material layer 730 preferably has a small in-plane retardation Re (550) as described in the first configuration example of the base material, and among them, the first base material layer 730 is optically or the like. It is preferable to have an in-plane retardation Re (550) of 10 nm or less so that it can function as an anisotropic layer. Such an organic EL display device 70 can obtain the same advantages as the organic EL display device 60 shown in FIG.

FIG. 8 is a cross-sectional view schematically showing an example of an organic EL display device 80 as a display device according to still another embodiment of the present invention.
As shown in FIG. 8, the organic EL display device 80 is provided in the same manner as the organic EL display device 60 shown in FIG. 6, except that the polarizing element protective film 800 is provided instead of the polarizing element protective film 650. .. Specifically, the organic EL display device 80 is an organic EL element 610 as a display element; a retardation film 620 having a predetermined in-plane retardation and capable of functioning as a λ / 4 plate; a polarizing element 630; and a laser. A polarizing element protective film 800; which contains an absorbent and contains a substrate 810 which can function as a λ / 4 plate; is provided in this order.

Further, the base material 810 has an organic EL display shown in FIG. 7, except that a third base material layer 850 containing a laser absorber is provided between the first base material layer 730 and the second base material layer 720. It is provided in the same manner as the base material 710 of the device 70. Specifically, the base material 810 is a second base material layer 720 including a first outer layer 721, an intermediate layer 722 containing a laser absorber, and a second outer layer 723 in this order; a third base material containing a laser absorber. The layer 850; the first base material layer 730 containing the laser absorber; and the conductive layer 740; are provided in this order from the polarizing element 630 side. The third base material layer 850 is similar to the first base material layer described in the first configuration example of the base material so that the third base material layer 850 can function as an optically isotropic layer. It is preferable to have an in-plane retardation Re (550) of 10 nm or less. Such an organic EL display device 80 can obtain the same advantages as the organic EL display device 60 shown in FIG.

FIG. 9 is a cross-sectional view schematically showing an example of an organic EL display device 90 as a display device according to still another embodiment of the present invention.
As shown in FIG. 9, the organic EL display device 90 is provided in the same manner as the organic EL display device 60 shown in FIG. 6, except that the polarizing element protective film 900 is provided instead of the polarizing element protective film 650. .. Specifically, the organic EL display device 90 is an organic EL element 610 as a display element; a retardation film 620 having a predetermined in-plane retardation and capable of functioning as a λ / 4 plate; a polarizing element 630; and a laser. A polarizing element protective film 900; which contains an absorbent and contains a substrate 910 which can function as a λ / 4 plate; is provided in this order.

Further, the base material 910 is provided with a fourth base material layer 960 containing a laser absorber on the side opposite to the first base material layer 730 of the second base material layer 720, except that the organic EL shown in FIG. 7 is provided. It is provided in the same manner as the base material 710 of the display device 70. Specifically, the base material 910 includes a first outer layer 961, an intermediate layer 962 which may contain a laser absorber, and a second outer layer 963 in this order; a fourth base material layer 960; a first outer layer 721. , An intermediate layer 722 containing a laser absorber, a second base material layer 720 including a second outer layer 723 in this order; a first base material layer 730 containing a laser absorber; and a conductive layer 740; Prepare in this order. Such an organic EL display device 90 can obtain the same advantages as the organic EL display device 60 shown in FIG. In particular, in this organic EL display device 90, in order to enable the combination of the second base material layer 720 and the fourth base material layer 960 to exhibit the function as a broadband λ / 4 plate, the second base material layer 720 Can function as a λ / 4 plate, and the fourth base material layer 960 can function as a λ / 2 plate. At this time, the crossing angle formed by the in-plane retardation and the slow axis of the second base material layer 720 and the fourth base material layer 960 is the first base material layer 410 and the second base in the second configuration example of the base material. It can be similar to the material layer 420 (see FIG. 4).

Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the examples shown below, and may be arbitrarily modified and carried out without departing from the scope of claims of the present invention and the equivalent scope thereof.

In the following description, "%" and "part" representing quantities are based on weight unless otherwise specified. Further, the operations described below were performed in the air at normal temperature and pressure unless otherwise specified.

[Measurement method of letteration]
The in-plane retardation was measured using a phase difference meter (“AxoScan” manufactured by Axometrics).

[Evaluation method of processability by laser light]
The circularly polarizing plate or the polarizing plate produced in the examples or comparative examples was placed on a slider as an evaluation sample. _{A CO 2} laser beam having a wavelength of 9.4 μm was applied to the surface of the evaluation sample on the side of the protector protective film. The output of the laser beam was adjusted so that the part other than the glass plate of the evaluation sample could be cut. Specifically, the output of the laser light is initially set to a low output and then gradually increased, and the laser light is irradiated when the part other than the glass plate of the evaluation sample can be cut or when the glass plate is broken. It stopped. After irradiating the laser beam as described above, the evaluation sample was observed and evaluated according to the following criteria.
"A": The portion other than the glass plate of the evaluation sample could be cut without damaging the glass plate, and the cut surface was flat and in a good cutting state.
"B": The part other than the glass plate of the evaluation sample could be cut without damaging the glass plate. However, the cut surface of the polarizing element included in the evaluation sample had irregularities due to heat melting or swelling of the resin.
"C": The evaluation sample could not be cut, or the glass plate was broken.

[Durability evaluation method by heat cycle test of circularly polarizing plate and polarizing plate]
A heat cycle test was performed using a circular polarizing plate or a polarizing plate manufactured in Examples or Comparative Examples as an evaluation sample using a thermal shock device (“TSA-71L-A” manufactured by ESPEC CORPORATION). In this heat cycle test, a continuous operation of cooling at a temperature of −45 ° C. for 30 minutes and then heating at a temperature of 85 ° C. for 30 minutes was defined as one cycle, and 50 cycles of cooling and heating were performed. After this heat cycle test, the crack generation state over the entire length of the circular polarizing plate or the polarizing plate as the evaluation sample was visually observed and evaluated according to the following criteria.
"A": There were no cracks or cracks in the polarizing element forming the polarizing plate.
"B": There were 20 or less cracks in the polarizing element forming the polarizing plate.
"C": There were 20 or more cracks in the polarizing element forming the polarizing plate.

[Manufacturing example 1. Manufacture of thermoplastic resin (J1)]
Pellets of a thermoplastic resin (J0) as a norbornene polymer (manufactured by Zeon Corporation, glass transition temperature Tg = 126 ° C.) were dried at 100 ° C. for 5 hours. 100 parts of the dried pellets and 5.0 parts of a laser absorber (pentaerythritol tetrabenzoate, molecular weight 552, melting point 102.0 ° C to 106.0 ° C) were mixed by a twin-screw extruder. The obtained mixture was put into a hopper connected to a single-screw extruder and extruded by melting from the single-screw extruder to obtain a thermoplastic resin (J1). The glass transition temperature Tg of this thermoplastic resin (J1) was 105 ° C.

[Manufacturing example 2. Manufacture of thermoplastic resin (J3)]
Instead of the thermoplastic resin (J0) used in Production Example 1, a thermoplastic resin (J2) as a norbornene polymer (manufactured by Zeon Corporation, glass transition temperature Tg = 163 ° C.) was used. Further, in addition to the laser absorber, 12.0 parts of a benzotriazole-based ultraviolet absorber (“LA-31” manufactured by ADEKA Corporation) was further added. Except for the above items, a thermoplastic resin (J3) was obtained in the same manner as in Production Example 1. The glass transition temperature Tg of this thermoplastic resin (J3) was 126 ° C.

[Manufacturing example 3. Manufacture of λ / 4 plate (Q1)]
The thermoplastic resin (J3) produced in Production Example 2 was dried at 100 ° C. for 5 hours. The dried thermoplastic resin (J3) was supplied to the extruder and melted in the extruder. The molten thermoplastic resin (J3) was extruded from the T-die onto the casting drum in the form of a sheet through a polymer pipe and a polymer filter. The extruded thermoplastic resin (J3) was cooled to obtain a pre-stretched substrate (Q0) having a thickness of 145 μm and an in-plane retardation Re (550) of 8 nm. The obtained pre-stretched substrate (Q0) was wound up to obtain a roll.

Next, the pre-stretched base material (Q0) was pulled out from the roll of the pre-stretched base material (Q0). The drawn out pre-stretching base material (Q0) was supplied to a tenter stretching machine and subjected to diagonal stretching treatment to obtain a stretched film. The diagonal stretching process refers to a stretching process in an oblique direction that is neither parallel nor perpendicular to the width direction of the film. The stretching ratio in this diagonal stretching treatment was 4.0 times, and the stretching temperature was 155 ° C. The angle of the slow axis of the obtained stretched film with respect to the width direction of the stretched film was 45 °. The in-plane retardation Re (550) of the stretched film was 125 nm and the thickness was 36 μm. The obtained stretched film was wound up as a λ / 4 plate (Q1) and recovered.

[Manufacturing example 4. Manufacture of λ / 4 plate (Q3)]
A double-flight single-screw extruder (screw diameter D = 50 mm, effective screw length L to screw diameter D ratio L / D = 28) equipped with a leaf disk-shaped polymer filter with a mesh opening of 3 μm is available. did. The thermoplastic resin (J3) produced in Production Example 2 was introduced into this single-screw extruder as a resin for forming an intermediate layer and melted. The molten thermoplastic resin (J3) was supplied to the single-layer die via the feed block under the conditions of an extruder outlet temperature of 260 ° C. and an extruder gear pump rotation speed of 10 rpm. The arithmetic mean roughness Ra of the die slip of this single-layer die was 0.1 μm.

On the other hand, a single-screw extruder (screw diameter D = 50 mm, effective screw length L to screw diameter D ratio L / D = 28) equipped with a leaf disk-shaped polymer filter having an opening of 3 μm was prepared. .. A thermoplastic resin (J0) was introduced into this single-screw extruder as a thermoplastic resin for forming the first outer layer and the second outer layer, and melted. The molten thermoplastic resin (J0) was supplied to the single-layer die via a feed block under the conditions of an extruder outlet temperature of 285 ° C. and an extruder gear pump rotation speed of 4 rpm.

Next, the above-mentioned film is discharged so as to include three layers of a resin layer for forming a first outer layer, a resin layer for forming an intermediate layer, and a resin layer for forming a second outer layer. The thermoplastic resins (J0) and (J3) were co-extruded from the single layer die at 280 ° C. Then, the thermoplastic resins (J0) and (J3) discharged from the single-layer die were cast on a cooling roll whose temperature was adjusted to 150 ° C. to obtain a pre-stretched substrate (Q2) having a thickness of 70 μm. The pre-stretched substrate (Q2) is a first outer layer (thickness 17.5 μm) made of a thermoplastic resin (J0) / an intermediate layer (thickness 35 μm) made of a thermoplastic resin (J3) / a thermoplastic resin (J0). It was a film composed of two types and three layers of a second outer layer (thickness 17.5 μm). Here, the two-kind three-layer represents the structure of a three-layer film made of two kinds of resins. The obtained pre-stretched substrate (Q2) was wound up to obtain a roll.

Next, the pre-stretched base material (Q2) was pulled out from the roll of the pre-stretched base material (Q2). The pulled-out pre-stretching base material (Q2) was supplied to a tenter stretching machine and subjected to diagonal stretching treatment to obtain a stretched film. The stretching ratio in this diagonal stretching treatment was 1.47 times, and the stretching temperature was 140 ° C. The angle of the slow axis of the obtained stretched film with respect to the width direction of the stretched film was 45 °. The in-plane retardation Re (550) of the diagonally stretched film was 104 nm and the thickness was 48 μm. The obtained stretched film was wound up as a λ / 4 plate (Q3) and recovered.

[Manufacturing example 5. Manufacture of λ / 2 plate (H1)]
The thermoplastic resin (J0) used in Production Example 1 was dried at 100 ° C. for 5 hours. The dried thermoplastic resin (J0) was supplied to the extruder and melted in the extruder. The molten thermoplastic resin (J0) was extruded from the T-die onto the casting drum in the form of a sheet through a polymer pipe and a polymer filter. The extruded thermoplastic resin (J0) was cooled to obtain a pre-stretched substrate (H0) having a thickness of 70 μm. The obtained pre-stretched substrate (H0) was wound up to obtain a roll.

Next, the pre-stretched base material (H0) was pulled out from the roll of the pre-stretched base material (H0). The drawn out pre-stretching base material (H0) was supplied to a tenter stretching machine and subjected to diagonal stretching treatment to obtain an intermediate film. The stretching ratio in this diagonal stretching treatment was 1.65 times, and the stretching temperature was 140 ° C. The obtained intermediate film was subjected to a longitudinal stretching treatment while being continuously conveyed in the longitudinal direction to obtain a stretched film. The longitudinal stretching process means a stretching process in the longitudinal direction of the film. The stretching ratio in this longitudinal stretching treatment was 1.45 times, and the stretching temperature was 135 ° C. The angle between the slow axis of the obtained stretched film with respect to the width direction of the stretched film was 75 °. The in-plane retardation Re (550) of the stretched film was 245 nm and the thickness was 30 μm. The obtained stretched film was wound as a λ / 2 plate (H1) and recovered.

[Manufacturing example 6. Manufacture of λ / 2 plate (H2)]
The pre-stretched base material (Q2) was pulled out from the roll of the pre-stretched base material (Q2) obtained in Production Example 4. The pulled-out pre-stretching base material (Q2) was supplied to a tenter stretching machine and subjected to diagonal stretching treatment to obtain an intermediate film. The stretching ratio in this diagonal stretching treatment was 1.7 times, and the stretching temperature was 131 ° C. The obtained intermediate film was subjected to a longitudinal stretching treatment while being continuously conveyed in the longitudinal direction to obtain a stretched film. The stretching ratio in this longitudinal stretching treatment was 1.5 times, and the stretching temperature was 125 ° C. The angle between the slow axis of the obtained stretched film with respect to the width direction of the stretched film was 75 °. The in-plane retardation Re (550) of the stretched film was 245 nm and the thickness was 27 μm. The obtained stretched film was wound up as a λ / 2 plate (H2) and recovered.

[Manufacturing example 7. Manufacture of λ / 2 plate (H3)]
A polymerizable liquid crystal compound represented by the following formula (A1) was prepared. This liquid crystal compound is a reverse wavelength dispersible liquid crystal compound. 21.25 parts of the liquid crystal compound represented by this formula (A1), 0.11 parts of the surfactant (“Surflon S420” manufactured by AGC Seimi Chemical Co., Ltd.), 0.64 parts of the polymerization initiator (“IRGACURE379” manufactured by BASF). , And 78.00 parts of a solvent (cyclopentanone, manufactured by Nippon Zeon Co., Ltd.) were mixed to prepare a liquid crystal composition A.

As a support, a λ / 2 plate (H1) as a stretched film obtained in Production Example 5 was prepared. The support was unwound from the roll and conveyed in its longitudinal direction at room temperature of 25 ° C. The liquid crystal composition A was directly applied onto the conveyed support using a die coater to form a layer of the liquid crystal composition A. The layer of the liquid crystal composition A was subjected to an orientation treatment at 110 ° C. for 2.5 minutes. Then, under a nitrogen atmosphere (oxygen concentration of 0.1% or less), ^{the liquid crystal composition A is subjected to ultraviolet rays having an integrated light intensity of 1000 mJ / cm 2 on} the side opposite to the layer of the liquid crystal composition A of the support. The layer was irradiated. The layer of the liquid crystal composition A was cured by irradiation with ultraviolet rays to form an optically anisotropic layer having a dry film thickness of 4.4 μm. As a result, a multi-layer film including the support and the optically anisotropic layer formed on the support was obtained. The optically anisotropic layer was a layer formed of a cured product of the liquid crystal composition A, and contained homogenically oriented cured liquid crystal molecules. The angle formed by the slow axis of the optically anisotropic layer with respect to the width direction of the film was 75 °. Further, the optically anisotropic layer had an in-plane retardation Re (550) having a wavelength of 240 nm and functioned as a λ / 2 plate. Therefore, this optically anisotropic layer was designated as a λ / 2 plate (H3).

[Manufacturing example 8. Manufacture of λ / 4 plate (Q4)]
A commercially available diagonally stretched film made of an alicyclic structure-containing polymer (the angle formed by the slow axis with respect to the width direction is 45 °, the thickness is 60 μm, and the in-plane retardation Re (550) is 141 nm) was prepared. This commercially available diagonally stretched film was used as a support instead of the λ / 2 plate (H1) used in Production Example 7. Further, the thickness of the layer of the liquid crystal composition A formed on the support was changed so that an optically anisotropic layer having a dry film thickness of 2.2 μm could be obtained. Except for the above items, a multilayer film including a support and an optically anisotropic layer formed on the support was obtained in the same manner as in Production Example 7. The optically anisotropic layer was a layer formed of a cured product of the liquid crystal composition A, and contained homogenically oriented cured liquid crystal molecules. The angle formed by the slow axis of the optically anisotropic layer with respect to the width direction of the film was 45 °. Further, the optically anisotropic layer had an in-plane retardation Re (550) of 139 nm and functioned as a λ / 4 plate. The Re (450) / Re (550) of this optically anisotropic layer was 0.83. Therefore, this optically anisotropic layer was designated as a λ / 4 plate (Q4).

[Manufacturing example 9. Manufacture of λ / 4 plate (Q6)]
As the thermoplastic resin for forming the first outer layer and the second outer layer, a thermoplastic resin (J2) was used instead of the thermoplastic resin (J0). Except for the above items, a pre-stretched base material (Q5) having a thickness of 70 μm was obtained in the same manner as in the method for producing the pre-stretched base material (Q2) in Production Example 4. The pre-stretched substrate (Q5) is a first outer layer (thickness 17.5 μm) made of a thermoplastic resin (J2) / an intermediate layer (thickness 35 μm) made of a thermoplastic resin (J3) / a thermoplastic resin (J2). It was a film composed of two types and three layers of a second outer layer (thickness 17.5 μm). The obtained pre-stretched substrate (Q5) was wound up to obtain a roll.

Next, the pre-stretched base material (Q5) was pulled out from the roll of the pre-stretched base material (Q5). The pulled-out pre-stretching base material (Q5) was supplied to a tenter stretching machine and subjected to diagonal stretching treatment to obtain a stretched film. The stretching ratio in this diagonal stretching treatment was 2.0 times, and the stretching temperature was 180 ° C. The angle of the slow axis of the obtained stretched film with respect to the width direction of the stretched film was 45 °. The in-plane retardation Re (550) of the diagonally stretched film was 130 nm and the thickness was 35 μm. The obtained stretched film was wound up as a λ / 4 plate (Q6) and recovered.

[Example 1]
As the polarizing element protective film, the λ / 4 plate (Q1) manufactured in Production Example 3 was prepared. This polarizing element protective film, adhesive (“CS9621T” manufactured by Nitto Denko Corporation), polarizing element (“HLC2-5618S” manufactured by Sanritz Co., Ltd., thickness 180 μm, having a transmission axis in the direction of 0 ° with respect to the width direction), A pressure-sensitive adhesive (“CS9621T” manufactured by Nitto Denko Corporation) and a glass plate (thickness 0.7 mm) were laminated in this order to produce a circularly polarizing plate (P1). In the obtained circularly polarizing plate (P1), the crossing angle between the slow axis of the λ / 4 plate (Q1) and the transmission axis of the polarizing element was 45 °. As a result of evaluating the processability of this circularly polarizing plate (P1) by laser light, it was based on "A". Moreover, as a result of evaluating the durability by the heat cycle test, it was the "A" standard.

[Example 2]
As the polarizing element protective film, the λ / 4 plate (Q3) manufactured in Production Example 4 was used instead of the λ / 4 plate (Q1) used in Example 1. A circularly polarizing plate (P2) was manufactured in the same manner as in Example 1 except for the above items. In the obtained circularly polarizing plate (P2), the crossing angle between the slow axis of the λ / 4 plate (Q3) and the transmission axis of the polarizing element was 45 °. As a result of evaluating the processability of this circularly polarizing plate (P2) by laser light, it was based on "B". Moreover, as a result of evaluating the durability by the heat cycle test, it was the "B" standard.

[Example 3]
The pre-stretched substrate (Q0) having optical isotropic properties obtained in Production Example 3 and the λ / 4 plate (Q1) obtained in Production Example 3 are bonded via an adhesive (“CS9621T” manufactured by Nitto Denko KK). And pasted together to obtain a laminated body. This laminated body was used as a polarizing element protective film instead of the λ / 4 plate (Q1) used in Example 1. A circularly polarizing plate (P3) was manufactured in the same manner as in Example 1 except for the above items. In the obtained circularly polarizing plate (P3), the crossing angle between the slow axis of the λ / 4 plate (Q1) of the laminated body and the transmission axis of the polarizing element was 45 °. As a result of evaluating the processability of this circularly polarizing plate (P3) by laser light, it was based on "A". Moreover, as a result of evaluating the durability by the heat cycle test, it was the "A" standard.

[Example 4]
The λ / 4 plate (Q1) obtained in Production Example 3 and the λ / 2 plate (H1) obtained in Production Example 5 are bonded together via an adhesive (“CS9621T” manufactured by Nitto Denko Corporation) to form a wide band. A λ / 4 plate was obtained. This wideband λ / 4 plate was used as a polarizing element protection film instead of the λ / 4 plate (Q1) used in Example 1. A circularly polarizing plate (P4) was manufactured in the same manner as in Example 1 except for the above items. In the obtained circularly polarizing plate (P4), the crossing angle between the slow axis of the λ / 4 plate (Q1) of the broadband λ / 4 plate and the slow axis of the λ / 2 plate (H1) was 60 °. .. The crossing angle between the slow axis of the λ / 2 plate (H1) and the transmission axis of the polarizing element was 15 °. As a result of evaluating the processability of this circularly polarizing plate (P4) by laser light, it was based on "A". Moreover, as a result of evaluating the durability by the heat cycle test, it was the "A" standard.

[Example 5]
The λ / 4 plate (Q1) obtained in Production Example 3 and the λ / 2 plate (H2) obtained in Production Example 6 are bonded together via an adhesive (“CS9621T” manufactured by Nitto Denko Corporation) to form a wide band. A λ / 4 plate was obtained. This wideband λ / 4 plate was used as a polarizing element protection film instead of the λ / 4 plate (Q1) used in Example 1. A circularly polarizing plate (P5) was manufactured in the same manner as in Example 1 except for the above items. In the obtained circularly polarizing plate (P5), the crossing angle between the slow axis of the λ / 4 plate (Q1) of the wideband λ / 4 plate and the slow axis of the λ / 2 plate (H2) was 60 °. .. The crossing angle between the slow axis of the λ / 2 plate (H2) and the transmission axis of the polarizing element was 15 °. As a result of evaluating the processability of this circularly polarizing plate (P5) by laser light, it was based on "A". Moreover, as a result of evaluating the durability by the heat cycle test, it was the "A" standard.

[Example 6]
The λ / 4 plate (Q1) obtained in Production Example 3 and the λ / 2 plate (H3) as the optically anisotropic layer of the multi-layer film obtained in Production Example 7 were used as an adhesive (Nitto Denko Corporation). It was pasted together via "CS9621T"). Then, the support of the multilayer film was peeled off to obtain a wide-wavelength λ / 4 plate provided with a λ / 4 plate (Q1), an adhesive and a λ / 2 plate (H3) in this order. This wideband λ / 4 plate was used as a polarizing element protection film instead of the λ / 4 plate (Q1) used in Example 1. A circularly polarizing plate (P6) was manufactured in the same manner as in Example 1 except for the above items. In the obtained circularly polarizing plate (P6), the crossing angle between the slow axis of the λ / 4 plate (Q1) of the wideband λ / 4 plate and the slow axis of the λ / 2 plate (H3) was 60 °. The crossing angle between the slow axis of the λ / 2 plate (H3) and the transmission axis of the polarizing element was 15 °. As a result of evaluating the processability of this circularly polarizing plate (P6) by laser light, it was based on "A". Moreover, as a result of evaluating the durability by the heat cycle test, it was the "A" standard.

[Example 7]
As the polarizing element protective film, the λ / 4 plate (Q6) manufactured in Production Example 9 was used instead of the λ / 4 plate (Q1) used in Example 1. A circularly polarizing plate (P7) was manufactured in the same manner as in Example 1 except for the above items. In the obtained circularly polarizing plate (P7), the crossing angle between the slow axis of the λ / 4 plate (Q6) and the transmission axis of the polarizing element was 45 °. As a result of evaluating the processability of this circularly polarizing plate (P7) by laser light, it was based on "B". Moreover, as a result of evaluating the durability by the heat cycle test, it was the "A" standard.

[Comparative Example 1]
As the polarizing element protective film, instead of the λ / 4 plate (Q1) used in Example 1, a pre-stretched film containing no laser absorber (Zeon Corporation "Zeonoa Film ZF14-100", thickness 100 μm, resin). Glass transition temperature 136 ° C.) was used. This pre-stretched film was an optically isotropic film made of a resin containing an alicyclic structure-containing polymer. Except for the above items, a polarizing plate (P7) was manufactured in the same manner as in Example 1. As a result of evaluating the processability of this polarizing plate (P7) by laser light, it was based on "C". Moreover, as a result of evaluating the durability by the heat cycle test, it was a "C" standard.

[Comparative Example 2]
As a polarizing element protective film, instead of the λ / 4 plate (Q1) used in Example 1, a diagonally stretched film containing no laser absorber (Zeon Corporation "diagonally stretched retardation film", thickness 47 μm, in-plane Lettering Re (550) was 125 nm, and the angle formed by the slow axis with respect to the width direction of the film was 45 °). This diagonally stretched film was a commercially available film made of a resin containing an alicyclic structure-containing polymer. A circularly polarizing plate (P8) was manufactured in the same manner as in Example 1 except for the above items. As a result of evaluating the processability of this circularly polarizing plate (P8) by laser light, it was based on "C". Moreover, as a result of evaluating the durability by the heat cycle test, it was a "C" standard.

[Example 8]
Λ manufactured in Production Example 4 via an adhesive (“CS9621T” manufactured by Nitto Denko Corporation) on the surface of the circularly polarizing plate (P1) manufactured in Example 1 opposite to the λ / 4 plate (Q1). A / 4 plate (Q3) was bonded as a retardation film. As a result, a visible side member (T1) including a polarizing element protective film, a pressure-sensitive adhesive, a polarizing element, a pressure-sensitive adhesive, a glass plate, a pressure-sensitive adhesive, and a retardation film was manufactured in this order. In the obtained visual recognition side member (T1), the crossing angle between the transmission axis of the polarizing element and the slow axis of the retardation film was 45 °.

(Manufacturing of image display device)
Two commercially available liquid crystal display devices (“iPad” (registered trademark) manufactured by Apple Inc.) equipped with a viewing side polarizing plate, a liquid crystal cell, a light source side polarizing plate, and a light source in this order were prepared.
The display surface portion of one of the liquid crystal display devices was disassembled, the viewing side polarizing plate of the liquid crystal display device was peeled off, and a viewing side member (T1) was attached instead. The viewing side member (T1) was attached so that the polarizing element protective film faced the viewing side. As a result, a liquid crystal display device including a visual recognition side member (T1), a liquid crystal cell as an image display element, a light source side polarizing plate, and a light source in this order was obtained from the visual recognition side.

(Naked eye observation)
The color and brightness of the display screen of one of the liquid crystal display devices to which the visual recognition side member (T1) was attached were visually observed with the naked eye. Further, with respect to the other liquid crystal display device to which the visual recognition side member (T1) was not attached, the color and brightness of the display screen were visually observed with the naked eye. The above observation was performed in the front direction of the display screen. As a result, the difference between the two liquid crystal displays could hardly be discerned.

(Observation of polarized sunglasses)
For one of the liquid crystal display devices to which the visual recognition side member (T1) was attached, polarized sunglasses were worn and the display screen was observed. Further, regarding the other liquid crystal display device to which the visual recognition side member (T1) was not attached, polarized sunglasses were worn and the display screen was observed. The above observation was performed in the tilting direction of the display screen. The tilting direction of a surface represents a direction that is neither parallel nor perpendicular to the surface. As a result, the brightness of one of the liquid crystal display devices to which the visual recognition side member (T1) was attached hardly changed even in the tilting direction as compared with the front direction of the display screen. On the other hand, in the other liquid crystal display device to which the visual recognition side member (T1) is not attached, the brightness changes and becomes darker in the tilting direction as compared with the front direction of the display screen.

[Example 9]
Λ manufactured in Production Example 8 via an adhesive (“CS9621T” manufactured by Nitto Denko Corporation) on the surface of the circularly polarizing plate (P1) manufactured in Example 1 opposite to the λ / 4 plate (Q1). A / 4 plate (Q4) was bonded as a retardation film. As a result, a visible side member (T2) including a polarizing element protective film, an adhesive, a polarizing element, an adhesive, a glass plate, an adhesive, and a retardation film was manufactured in this order. In the obtained visual recognition side member (T2), the crossing angle between the transmission axis of the polarizing element and the slow axis of the retardation film was 45 °.

(Manufacturing of image display device)
A commercially available OLED smartphone (“G FlexLGL23” manufactured by LG Electronics) equipped with a polarizing plate on the viewing side and an organic EL display element in this order was prepared.
The viewing side polarizing plate of this smartphone was peeled off, and a viewing side member (T2) was attached instead. The viewing side member (T2) was attached so that the polarizing element protective film was facing the viewing side. As a result, an organic EL display device including a circularly polarizing plate was obtained. The luminance of this organic EL display device at the time of black display and white display was 6.2 cd / m ² and 305 cd / m ² , respectively.

The display screen was visually observed from the front with the organic EL display device displayed in black under outside light on a sunny day. As a result, there was no reflection of external light on the display screen, and the display screen was black. Further, when the display screen was visually observed from an oblique direction (extreme angle 45 °, omnidirectional), no change in reflectance and color due to the azimuth was observed.

10 Display device 50 Liquid crystal display device 60 Organic EL display device 110 Polarizer protective film 111 Base material 120 Polarizer 130 Phase difference film 140 Display element 200 Resin layer 210 First outer layer 220 Second outer layer 230 Intermediate layer 300 Base material 310 First base material layer 320 Second base material layer 330 Conductive layer 400 Base material 410 First base material layer 420 Second base material layer 430 Conductive layer 510 Light source 520 Light source side polarizing element 530 Liquid crystal cell 540 Phase difference film 550 Visually visible side polarized light Child 560 Base material 561 Second base material layer 562 First outer layer 563 Intermediate layer 564 Second outer layer 565 First base material layer 566 Conductive layer 570 Polarizer protective film 610 Organic EL element 620 Phase difference film 630 Polarizer 640 units Material 641 First outer layer 642 Intermediate layer 643 Second outer layer 644 Second base material layer 645 First outer layer 646 Intermediate layer 647 Second outer layer 648 First base material layer 649 Conductive layer 650 Polarizer protective film

Claims (13)

A display device including a polarizing element protective film, a polarizing element, a retardation film, and a display element in this order.
The polarizing element protective film contains a base material containing a laser absorber and capable of functioning as a λ / 4 plate.
The phase difference in-plane retardation Re at a wavelength of 550nm of the film (550), Ri 90nm~150nm der,
The substrate is a first substrate layer having an in-plane retardation Re (550) at a wavelength of 550 nm of 10 nm or less, and a second substrate layer having an in-plane retardation Re (550) at a wavelength of 550 nm of 90 nm to 150 nm. And a conductive layer formed on at least one surface of the first base material layer.
The laser absorber is contained in one or both of the first base material layer and the second base material layer.
One or both of the first base material layer and the second base material layer are provided between the first outer layer, the second outer layer, and the first outer layer and the second outer layer. And, including
The first outer layer is formed of a first outer resin having a glass transition temperature of Tg _O1.
The second outer layer is formed of a second outer resin having a glass transition temperature of Tg _O2.
The intermediate layer is formed of an intermediate resin having a glass transition temperature Tg _C.
The difference Tg _{C −} Tg _O1 between the glass transition temperature Tg _O1 of the first outer resin and the glass transition temperature Tg _C of the intermediate resin is 30 ° C. or higher.
A display device in which the difference Tg _{C −} Tg _O2 between the glass transition temperature Tg _O2 of the second outer resin and the glass transition temperature Tg _C of the intermediate resin is 30 ° C. or higher. A display device including a polarizing element protective film, a polarizing element, a retardation film, and a display element in this order.
The polarizing element protective film contains a base material containing a laser absorber and capable of functioning as a λ / 4 plate.
The in-plane retardation Re (550) of the retardation film at a wavelength of 550 nm is 90 nm to 150 nm, and the base material can function as a λ / 4 plate and a first base material layer that can function as a λ / 2 plate. It includes a two-base material layer and a conductive layer formed on at least one surface of the first base material layer, and can function as a broadband λ / 4 plate.
The laser absorber is contained in one or both of the first base material layer and the second base material layer .
One or both of the first base material layer and the second base material layer are provided between the first outer layer, the second outer layer, and the first outer layer and the second outer layer. And, including
The first outer layer is formed of a first outer resin having a glass transition temperature of Tg _O1.
The second outer layer is formed of a second outer resin having a glass transition temperature of Tg _O2.
The intermediate layer is formed of an intermediate resin having a glass transition temperature Tg _C.
The difference Tg _{C −} Tg _O1 between the glass transition temperature Tg _O1 of the first outer resin and the glass transition temperature Tg _C of the intermediate resin is 30 ° C. or higher.
A display device in which the difference Tg _{C −} Tg _O2 between the glass transition temperature Tg _O2 of the second outer resin and the glass transition temperature Tg _C of the intermediate resin is 30 ° C. or higher. The display device according to claim 2 , wherein the second base material layer is formed of a cured product of a liquid crystal composition containing a liquid crystal compound. The display device according to any one of claims 1 to 3, wherein the intermediate layer contains an ultraviolet absorber. The display device according to any one of claims 1 to 4 , wherein the thickness of one or both of the first base material layer and the second base material layer is 10 μm to 60 μm. The display device according to any one of claims 1 to 5 , wherein the slow axis of the base material and the transmission axis of the substituent intersect. The display device according to claim 6 , wherein the crossing angle between the slow axis of the base material and the transmission axis of the polarizing element is 45 ° ± 5 °. The display device according to any one of claims 1 to 7 , wherein the base material contains a polymer having crystallinity. The display device according to any one of claims 1 to 8 , wherein the base material and the retardation film each contain an alicyclic structure-containing polymer. The display device according to any one of claims 1 to 9 , wherein the base material and the retardation film each include a stretched film. The retardation film is formed of a cured product of a liquid crystal composition containing a liquid crystal compound.
The in-plane retardation Re (450) of the retardation film at a wavelength of 450 nm and the in-plane retardation Re (550) of the retardation film at a wavelength of 550 nm are Re (450) / Re (550) <1.0. The display device according to any one of claims 1 to 8 , which satisfies the above conditions. The display device according to any one of claims 1 to 11 , wherein the display element is a liquid crystal cell. The display device according to any one of claims 1 to 11 , wherein the display element is an organic electroluminescence element.

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