JP6911520B2 - Alignment film, and transparent conductive film using it, touch panel and display device - Google Patents

Description

The present invention relates to an alignment film, and a transparent conductive film using the alignment film, a touch panel, and a display device.

Conventionally, plastic films have been used in various fields. Plastic films are often stretched at the time of manufacture in order to increase their mechanical strength.
In the stretched plastic film, the polymers constituting the film are oriented to form an oriented film. Such an alignment film is used, for example, in a display device such as a liquid crystal display device (surface protection film, a base material of a transparent conductive film), an automobile member (heat shield film for a window, a front plate of an instrument panel), and the like. Has been done.

When polarized light is incident on the alignment film, the light emitted from the alignment film becomes a "rainbow-shaped striped pattern (hereinafter, may be referred to as" rainbow unevenness ")" due to the birefringence of the alignment film. May be observed. In particular, a biaxially stretched polyester film, which is a typical example of an industrial film, is useful in that it is excellent in transparency and mechanical strength, but it tends to cause iridescent unevenness due to the birefringence described above.
As a technique for eliminating such rainbow-shaped unevenness, the techniques described in Patent Documents 1 and 2 and the like have been proposed.

Japanese Unexamined Patent Publication No. 2011-59488 Japanese Unexamined Patent Publication No. 2011-107198

Patent Documents 1 and 2 propose to increase the retardation value (Re) of the oriented film (aligned polyester film) to eliminate rainbow unevenness. The retardation value is the refractive index in the slow axis direction, which is the direction in which the refractive index is the largest in the plane, as "n _x ", and the refractive index in the phase advance axis direction, which is the direction orthogonal to the slow axis direction in the plane. _{"n y",} the thickness of the film when used as a "d" is a parameter calculated by the formula _{"Re = (n x -n y)} × d ".
In order to increase the retardation value of the alignment film, there are _{means for increasing n x −} n _y and means for increasing the film thickness. The latter means of increasing the film thickness has problems of cost increase and material thickening. Therefore, the former means of increasing _{n x −} n _{y is preferable.} Therefore, an oriented film having a large retardation value (hereinafter, may be referred to as a “high retardation film”) is usually produced by uniaxial stretching in which any one direction of the film is excessively stretched.

However, the high retardation film produced by uniaxial stretching may be deformed by an external factor such as heat because the difference in physical properties between the stretching direction and the direction orthogonal to the stretching direction becomes large. For example, when a high retardation film as in Patent Documents 1 and 2 is used as a base material for a transparent conductive film, a step of crystallizing the transparent conductive layer and a step of firing a take-out electrode made of silver paste or the like on the transparent conductive layer. In some cases, the base material (high retardation film) may be deformed by heat.

Further, in recent years, light sources and display elements of display devices have been diversified in order to improve brightness, resolution, color gamut, and the like. For example, as a light source for a backlight of a liquid crystal display device, a white LED used in Patent Document 2 has been often used in the past. The white LED is characterized in that the shape of the intensity distribution of the RGB spectral spectrum is broad.
On the other hand, in recent display elements, the shape of the intensity distribution of the RGB spectral spectrum is sharpened in order to improve the color rendering property (to widen the color gamut). In such a liquid crystal display device having high color rendering properties, for example, a quantum dot or a KSF phosphor is used as a light source.
Here, even if the high retardation films of Patent Documents 1 and 2 are used for a display device in which the shape of the intensity distribution of the RGB spectral spectrum is sharp, the rainbow unevenness may not be eliminated.

In addition to the means of Patent Documents 1 and 2, as a means of suppressing rainbow unevenness, an alignment film having uniform orientation in all directions can be considered. Such an alignment film can theoretically be produced if it is stretched simultaneously and evenly in two directions (preferably stretched simultaneously and evenly in all directions). However, the film is cost-effective because it requires extremely large manufacturing equipment to stretch at least two directions simultaneously and evenly, quality control is difficult, and good yield cannot be expected. Without it, it is not realistic.

An object of the present invention is to provide an alignment film capable of suppressing deformation and rainbow unevenness due to heat while having excellent mechanical strength, and a transparent conductive film, a touch panel and a display device using the same.

The present invention provides the following [1] to [4].
[1] Alignment film, the alignment film contains birefringent particles, the alignment film has a retardation value of less than 400 nm in an arbitrary region, and the surface orientation of the alignment film calculated by the following method. An oriented film having a degree ratio of more than 1.0 and not more than 3.0.
<Surface orientation ratio>
The absorption intensity (I ₁₃₄₀ ^{) of the alignment film at 1340 cm-1} in the range of 0 ° to 170 °, starting from the slow axis direction (0 degree), which is the direction in which the refractive index is the largest in the region of the alignment film. ) And the absorption intensity (I ₁₄₁₀ ^{) at 1410 cm-1} are measured every 10 degrees. _Let I 1340 / I _{1410 be} the orientation parameter Y for each angle. The maximum value among the measured 18-point orientation parameters Y is Y _max , the minimum value is Y _min , and Y _max / Y _min is the surface orientation ratio of the alignment film.

[2] A transparent conductive film having a transparent conductive layer on a transparent base material, wherein the transparent base material is the alignment film according to the above [1].
[3] A touch panel having a transparent conductive film as a constituent member, wherein the transparent conductive film is the transparent conductive film according to the above [2].

[4] A display device having a polarizer and one or more optical films on the surface of the display element on the light emitting surface side, and _{when the light emitted in the vertical direction from the display element is L 1} , the above. A display device in which L ₁ satisfies the following condition 1 and at least one of the optical films is the alignment film according to the above [1].
<Condition 1>
The intensity of L ₁ is measured every 1 nm. The blue wavelength range is 400 nm or more and less than 500 nm, the green wavelength range is 500 nm or more and less than 600 nm, and the red wavelength range is 600 nm or more and 780 nm or less. Maximum intensity _{B max} of the blue wavelength region of the _{L 1,} the maximum intensity _{G max} of the green wavelength region of the _{L 1,} the maximum intensity in the wavelength range of red of said _{L 1} and _{R max.}
Let _{L 1 λ B be the} wavelength indicating the B _{max , L 1} λ _{G be the} wavelength indicating the G _{max , and L 1} λ _{R be the} wavelength indicating the R _max .
The _{B max} of less than 1/2 of the intensity a wavelength showing an _{L 1} lambda minimum wavelength + alpha located in the positive direction side of the _{B B,} a wavelength showing an intensity of 1/2 or less of the _{G max} L _The maximum wavelength located on the negative side of 1 λ _{G is −α G} , and the minimum wavelength located on the positive side of _{L 1} λ _{G is + α G} , which is a wavelength showing an intensity of 1/2 or less of the _{G max.} Let _{−α R be} the maximum wavelength that is 1/2 or less of the intensity of R _max and is located on the negative side of _{L 1 λ R.}
L ₁ λ _B , L ₁ λ _G , L ₁ λ _R , + α _B , −α _G , + α _G and −α _R satisfy the following relationships (1) to (4).
+ Α _B <L ₁ λ _G (1)
L ₁ λ _B <-α _G (2)
+ Α _G <L ₁ λ _R (3)
L ₁ λ _G <-α _R (4)

The alignment film of the present invention, and the transparent conductive film, touch panel, and display device using the same can suppress deformation and rainbow unevenness due to heat while having excellent mechanical strength.

It is sectional drawing which shows one Embodiment of the alignment film of this invention. It is sectional drawing which shows the other embodiment of the alignment film of this invention. It is sectional drawing which shows one Embodiment of the transparent conductive film of this invention. It is sectional drawing which shows one Embodiment of the touch panel of this invention. It is sectional drawing which shows the other embodiment of the touch panel of this invention. It is sectional drawing which shows one Embodiment of the display device of this invention. This is an example of the spectral spectrum of _{light (L 1} ) emitted in the vertical direction from a three-color independent organic EL display element having a microcavity structure. This is an example of the spectral spectrum of _{light (L 1} ) emitted in the vertical direction from the display element of the liquid crystal display device in which the display element is a liquid crystal display element and the light source of the backlight is a cold cathode fluorescent tube (CCFL). This is an example of the spectral spectrum of _{light (L 1} ) emitted in the vertical direction from the display element of the liquid crystal display device in which the display element is a liquid crystal display element and the light source of the backlight is a white LED. This is an example of the spectral spectrum of _{light (L 1} ) emitted in the vertical direction from a color filter type organic EL display element provided with a white light emitting layer and a color filter. In a display device in which the display element is a liquid crystal display element, the primary light source of the backlight is a blue LED, the secondary light source is a quantum dot, and a polarizer and an optical film are provided on the display element, the direction is vertical from the display element side. This is an example of the spectral spectrum of _{the light (L 1} ) emitted from the light source. In a display device in which the display element is a liquid crystal display element, the primary light source of the backlight is a blue LED, the secondary light source is a quantum dot, and a polarizer and an optical film are provided on the display element, the direction is vertical from the display element side. This is another example of the spectral spectrum of _{the light (L 1} ) emitted from the light source.

Hereinafter, embodiments of the present invention will be described.
[Orientation film]
The alignment film of the present invention is an alignment film, the alignment film contains birefringent particles, the alignment film has a retardation value of less than 400 nm in an arbitrary region, and the alignment is calculated by the following method. The surface orientation ratio of the film is more than 1.0 and 3.0 or less.
<Surface orientation ratio>
Absorption strength of the ^{alignment film at 1340 cm -1} in the range of 0 to 170 degrees starting from the slow axis direction (0 degree), which is the direction in which the refractive index is the largest in the region in the plane of the alignment film. (I ₁₃₄₀ ) and absorption intensity (I ₁₄₁₀ ^{) at 1410 cm-1} are measured every 10 degrees. _Let I 1340 / I _{1410 be} the orientation parameter Y for each angle. The maximum value among the measured 18-point orientation parameters Y is Y _max , the minimum value is Y _min , and Y _max / Y _min is the surface orientation ratio of the alignment film.

1 and 2 are cross-sectional views showing an embodiment of the alignment film 100 of the present invention.
The alignment film 100 of FIG. 1 has a single-layer structure of the core layer 10, but the alignment film 100 of FIG. 2 has surface layers 20 on both sides of the core layer 10.
Further, both the alignment films 100 of FIGS. 1 and 2 contain the polymer compounds 11 and 21 and the birefringent particles 12 and 22 in the core layer 10 and the surface layer 20.

The retardation value of the alignment film of the present invention is less than 400 nm. When the retardation value of the alignment film is 400 nm or more, rainbow unevenness cannot be suppressed.
The rainbow unevenness is a rainbow-colored unevenness that occurs in a striped shape that is observed when polarized light is incident on the alignment film and is emitted. It is clearly visible when observed.

The retardation value of the alignment film is preferably 300 nm or less, more preferably 250 nm or less. The lower limit of the retardation value of the oriented film is not particularly limited, but it is preferably 10 nm or more in terms of production control.

In the present specification, the “retention value (Re)” refers to the refractive index in the slow-phase axial direction, which is the direction in which the refractive index is the largest in the plane, as “n _x ”, in the direction orthogonal to the slow-phase axial direction in the plane. the refractive index of a fast axis direction "n _y", the thickness of the oriented film upon as "d (nm)", is calculated by the formula "(n x _{-n y)} × d", so-called " It is a parameter called "in-plane refraction". Further, in the present specification, the refractive index and the retardation value refer to the refractive index and the retardation value at a wavelength of 589 nm.
The retardation value can be measured by, for example, the trade names "KOBRA-WR" and "PAM-UHR100" manufactured by Oji Measuring Instruments Co., Ltd.

Further, the alignment film of the present invention has a surface orientation ratio of the alignment film calculated by the above method of more than 1.0 and 3.0 or less.
When the surface orientation ratio of the film does not exceed 1.0, it means that the film is substantially unstretched or the orientation in all directions is uniform. When the former film is substantially unstretched, the mechanical strength of the film is insufficient. On the other hand, the latter film, which has a uniform orientation in all directions, can be theoretically manufactured if it is stretched simultaneously and evenly in all directions, but it requires extremely large manufacturing equipment and quality control is difficult. Moreover, since good yield cannot be expected, it will not be cost-effective. Normally, when the surface orientation ratio exceeds 1.0, it is difficult to set the retardation value of the alignment film to less than 400 nm. However, in the present invention, the surface orientation is due to the inclusion of the birefringent particles described later. It is possible to make the retarding value of the alignment film less than 400 nm while the ratio is more than 1.0.
Further, when the surface orientation ratio of the film exceeds 3.0, it means that the film is a uniaxially stretched film in which any one direction of the film is excessively stretched. Therefore, when the surface orientation ratio of the film exceeds 3.0, the difference in physical properties between the stretching direction and the direction orthogonal to the stretching direction becomes large, and deformation due to external factors such as heat cannot be suppressed.

The surface orientation ratio of the alignment film is preferably 1.2 or more and 2.8 or less, more preferably 1.5 or more and 2.5 or less, and further preferably 1.7 or more and 2.3 or less. preferable.
The surface orientation ratio of the alignment film can be adjusted, for example, by changing the vertical and horizontal stretch ratios when the alignment film is produced by biaxial stretching. The biaxial stretching is preferably "sequential stretching" in which the stretching in the longitudinal direction and the stretching in the horizontal direction are performed at different timings. That is, the alignment film of the present invention is preferably an alignment film that is sequentially biaxially stretched.

The alignment film of the present invention may have a retardation value and a surface orientation ratio in an arbitrary region in the alignment film within the above ranges, but from the viewpoint of making the effects of the present invention more easily exhibited, any of the alignment films in the alignment film. Also in the region, the retardation value and the surface orientation ratio are preferably in the above ranges.

Birefringent particles are included in the alignment film. In the present invention, the alignment film contains birefringent particles, so that the retardation value of the alignment film can be set to less than 400 nm while having the above-mentioned surface orientation ratio.
When the alignment film has a multilayer structure, the birefringent particles may be contained only in an arbitrary layer, but from the viewpoint of facilitating the retardation value of less than 400 nm, it is preferably contained in a layer having a large film thickness. , It is more preferable that it is contained in all layers. Further, from the viewpoint of suppressing blocking, it is preferable that the birefringent particles are contained in the layer located on the surface side.

The birefringent particles are particularly limited as long as they are oriented in substantially the same direction as the orientation direction of the polymer compound constituting the alignment film, cancel the birefringence of the polymer compound, and the retardation value of the alignment film can be less than 400 nm. Can be used without being used.
Both organic and inorganic birefringent particles can be used, but since they are excellent in birefringence, the birefringence of the polymer compound can be canceled by adding a small amount, and the heat resistance is good. Inorganic ones are preferable.
Note that "alignment in substantially the same direction" does not mean that the axial direction of all the birefringent particles is the same as the orientation direction of the polymer compound, but that the inorganic particles are oriented in parallel in the axial direction. It also means that there are many substances.

The birefringent particles capable of canceling the birefringence of the polymer compound are those in which the birefringence of the polymer compound and the positive and negative are opposite. For example, if the polymer compound constituting the alignment film exhibits positive birefringence, the birefringent particles having negative birefringence can cancel the birefringence of the polymer compound. On the contrary, if the polymer compound constituting the alignment film exhibits negative birefringence, the birefringent particles having positive birefringence can cancel the birefringence of the polymer compound.
_{The polymer compound exhibiting positive birefringence is n 1A for} the refractive index in the orientation axis direction (main axis direction) of the polymer compound constituting the alignment film, _{and n 2A for} the refractive index in the direction orthogonal to the orientation axis direction. When, it means that the relationship of _{n 1A} > n _{2A is satisfied.} On the contrary, a polymer compound exhibiting negative birefringence means a compound that satisfies the relationship of _{n 1A} <n _2A.

When the polymer compound exhibits positive birefringence, it is preferable because it is easy to improve the mechanical strength of the alignment film. Examples of the polymer compound exhibiting positive birefringence include polyesters such as polyethylene terephthalate and polyethylene naphthalate, and polycarbonates. Among these, polyester is preferable because it is excellent in mechanical strength and has a small photoelastic coefficient, so that the refractive index (≈ retardation value) of the relevant portion does not easily change even when a local stress is applied to the alignment film. That is, the alignment film is preferably a polyester film.
Examples of the polymer compound exhibiting negative birefringence include acrylic and polystyrene.

Examples of the particles having negative birefringence include magnesium carbonate, zirconium carbonate, strontium carbonate, cobalt carbonate, manganese carbonate, calcium carbonate and the like. These are preferably used in combination with the above-mentioned polymer compounds exhibiting positive birefringence. Further, among the particles having negative birefringence, calcium carbonate and strontium carbonate are preferable. Calcium carbonate and strontium carbonate are suitable in that the difference in refractive index from the polymer compound can be reduced and the transparency can be easily improved.
Particles having a positive birefringence are not exemplified, but particles having a positive birefringence are preferably used in combination with the above-mentioned polymer compound exhibiting a negative birefringence.

The birefringent particles preferably have an elongated shape such as a rod shape, a needle shape, or a spindle shape in order to facilitate orientation in the alignment film, and among these, the needle shape is preferable. The aspect ratio of the birefringent particles is preferably 1.5 or more, preferably 2.0 or more (length of the birefringent particles in the major axis direction / diameter in the direction perpendicular to the major axis direction). Is more preferable, and 3.0 or more is further preferable.
The average particle size of the birefringent particles is preferably 200 nm or less, and more preferably 100 nm or less from the viewpoint of transparency.

The average particle size of the birefringent particles can be calculated by the following operations (1) to (3).
(1) The cross section of the alignment film of the present invention is imaged by TEM or STEM. The acceleration voltage of TEM or STEM is preferably 10 kv to 30 kV, and the magnification is preferably 50,000 to 300,000 times.
(2) Arbitrary 10 birefringent particles are extracted from the observation image, and the particle size of each birefringent particle is calculated. The particle size is measured as the distance between two straight lines in a combination of two straight lines that maximizes the distance between the two straight lines when the cross section of the birefringent particle is sandwiched between two arbitrary parallel straight lines. ..
(3) The same operation is performed 5 times on the observation image on another screen of the same sample, and the value obtained from the number average of the particle sizes of a total of 50 particles is defined as the average particle size of the birefringent particles.

The birefringent particles are preferably surface-treated with a compound having high dispersibility with respect to the polymer compound in order to improve the dispersibility in the polymer compound. Alternatively, the birefringent particles are preferably surface-treated with a compound having high dispersibility in the solvent in order to improve the dispersibility in the solvent in which the polymer compound is dissolved.

The content of the birefringent particles is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, and 1 to 10 parts by mass with respect to 100 parts by mass of the polymer compound. Is more preferable.
By setting the content of the birefringent particles to 0.1 parts by mass or more, the retardation value can be easily set to less than 400 nm. Further, by setting the content of the birefringence particles to 30 parts by mass or less, the aggregation of the birefringence particles is suppressed, the birefringence of the polymer compound is canceled, the retardation value is easily reduced to less than 400 nm, and the transparency is good. Can be made easy.

The thickness of the alignment film is not particularly limited, but is preferably 15 to 300 μm, more preferably 20 to 200 μm, from the viewpoint of improving handleability and mechanical strength and making it easier for the retardation value to be less than 400 nm. It is more preferably 25 to 100 μm.
The thickness of the alignment film can be measured by, for example, a micrometer (trade name: Digimatic Micrometer, manufactured by Mitutoyo Co., Ltd.).

_N x -n _y in the region of the alignment film, from the viewpoint of easily retardation value less than 400 nm, preferably 0.025 or less, more preferably 0.020 or less, 0.010 or less Is more preferable.

The retardation value (Rth) in the thickness direction of the alignment film is preferably less than 400 nm, more preferably 300 nm or less, and further preferably 250 nm or less from the viewpoint of suppressing rainbow unevenness. The lower limit of Rth of the alignment film is not particularly limited, but is about 10 nm.
Note that the thickness direction retardation value (Rth), the refractive index in the thickness direction of the alignment film when used as a _{n z, "Rth = (| n x -n z} | + | n y -n z | ) / 2 ”is a parameter calculated. In addition, _nz shall be measured in the center of the above-mentioned region.

_{The variation of the refractive index nz} in the thickness direction of the alignment film is preferably 0.01 or less, and more preferably 0.005 or less. By _{setting the variation of nz} to 0.002 or less, the variation of Rth can be reduced.

Oriented film, of the tensile strength of 23 ° C., a slow axis direction of the tensile strength T _L, the tensile strength of the fast-axis direction orthogonal to the slow axis direction upon a T _S, T _L it is preferable to satisfy the relationship / _{T S} ≦ 3.0. By the T L _/ T _S and 3.0 or less, it is possible to suppress the orientation film is easily torn in the fast axis direction.
T _L / _{T S} is more preferably 1.0 Ultra 2.5 or less, further preferably 1.2 to 2.0.
Further, _{T S} is preferably at least 100 MPa, more preferably 120～200MPa.

Oriented film, of the Young's modulus of 23 ° C., a slow axis direction of the Young's modulus E _L, a fast axis direction of the Young's modulus in the direction perpendicular to the slow axis direction upon an E _S, E _L / _E preferably satisfies the relationship of _S ≦ 1.7. By the E L _/ E _S is 1.7 or less, upon heating the oriented film, oriented film it can be prevented from being deformed.
E _L / _{E S} is more preferably 1.0 Ultra 1.5 or less, still more preferably greater than 1.0 to 1.3.
Also, _{E S} is preferably at least 2.0 GPa, more preferably 2.5～3.5GPa.

The alignment film may contain additives such as an ultraviolet absorber and a light stabilizer as long as the effects of the present invention are not impaired. When the alignment film has a multilayer structure, it is preferable to contain an ultraviolet absorber and a light stabilizer in the core layer from the viewpoint of suppressing bleed-out.

The alignment film preferably has a haze of JIS K7136: 2000 of 10% or less, and more preferably 5% or less.
Further, the alignment film preferably has a total light transmittance of JIS K7361-1: 1997 of 80% or more, and more preferably 85% or more.

The width of the alignment film is not particularly limited. For example, when the alignment film is in the form of a sheet, the width is usually about 10 to 3000 mm, preferably 50 to 2000 mm. When the alignment film is in the form of a roll, the width is usually 1000 mm or more, preferably 1200 to 4000 mm.
The length of the alignment film is also not particularly limited. For example, when the alignment film is in the form of a sheet, the length is usually about 10 to 3000 mm, preferably 50 to 2000 mm. When the alignment film is in the form of a roll, the length is usually 300 to 6000 m, preferably 1000 to 5000 m.

The oriented film of the present invention can be produced, for example, by the following steps (A1) to (A3) and steps (B1) to (B3).
<In the case of single layer structure>
(A1) A composition in which birefringent particles are dispersed in a polymer compound is obtained.
(A2) An unstretched film obtained by molding the composition into a sheet is obtained.
(A3) The unstretched film is stretched in the flow direction (longitudinal stretching) at a temperature equal to or higher than the glass transition temperature of the polymer compound, and then stretched in the width direction (horizontal direction).
After the step (A3), it is preferable to carry out the (A4) heat treatment step in order to suppress the shrinkage of the alignment film.

The composition of step (A1) can be obtained, for example, by the following methods (i) to (iii).
(I) A method of mixing birefringent particles before the start of the polymerization reaction for synthesizing a polymer compound or before the end of the polymerization reaction. That is, the composition of the step (A1) can be obtained by mixing birefringent particles that are not involved in the polymerization reaction of the monomer into the monomer that gives the polymer compound and sufficiently dispersing them, and then proceeding the polymerization reaction. can.
(Ii) A method of adding birefringent particles to a heated melt of a polymer compound and dispersing the birefringent particles in a matrix through a process of kneading the particles.
(Iii) A method of dispersing birefringent particles in a solution in which a polymer compound is dissolved in a solvent.

As a means for forming the composition into a sheet in the step (A2), a means for melting the composition obtained in the above (i) or (ii) and extruding it into a sheet, or a means obtained in the above (iii). Examples thereof include means for applying the obtained composition and evaporating the solvent.
The temperature at the time of stretching and the stretching ratio in the step (A3) may be adjusted according to the type of the polymer compound and the desired physical property values (tensile strength, Young's modulus) for the alignment film. For example, in the case of a polyester film, the temperature is preferably 80 to 130 ° C., the stretching ratio in the vertical direction is preferably 1.3 to 4 times, and the stretching ratio in the horizontal direction is preferably 1.3 to 6 times. The ratio of the vertical stretching ratio to the horizontal stretching ratio [horizontal stretching ratio / longitudinal stretching ratio] is 1.5 to 4.0 from the viewpoint of keeping the surface orientation ratio in the above range. It is preferably 1.5 to 2.5, and more preferably 1.5 to 2.5.
The temperature of the heat treatment in the step (A4) may be adjusted according to the type of the polymer compound. For example, in the case of a polyester film, 100 to 250 ° C. is preferable, and 180 to 245 ° C. is more preferable.

<In the case of multi-layer structure>
(B1) A composition in which birefringent particles and / or additives are dispersed in a polymer compound is obtained for each layer.
(B2) The composition of each layer is melted and extruded using two or more extruders, passed through one die, the layers are laminated, and cooled to obtain a multilayer unstretched film.
(B3) The multilayer unstretched film is stretched in the flow direction (longitudinal stretching) at a temperature equal to or higher than the glass transition temperature, and then stretched in the width direction (horizontal direction).
After the step (B3), it is preferable to carry out the (B4) heat treatment step in order to suppress the shrinkage of the alignment film.

By changing the composition of each layer in the step (B2), a multilayer oriented film in which layers having different compositions are laminated can be obtained. For example, the following configurations (a) to (c) can be mentioned. In addition, "/" means the interface of a layer, and the inside of parentheses means a component contained in each layer.
(A) Surface layer (polymer compound, birefringent particles) / core layer (polymer compound, birefringence particles, ultraviolet absorber) / surface layer (polymer compound, birefringence particles)
(B) Surface layer (polymer compound, birefringent particles, slipper) / core layer (polymer compound, birefringence particles) / surface layer (polymer compound, birefringence particles, slipper)
(C) Surface layer (polymer compound, birefringent particles, slipper) / core layer (polymer compound, birefringence particles, ultraviolet absorber) / surface layer (polymer compound, birefringence particles, slipper)

<Use of alignment film>
The alignment film of the present invention can suppress the observation of rainbow-shaped stripes (rainbow unevenness) when polarized light is incident on the alignment film and emitted. Further, the alignment film of the present invention has excellent mechanical strength and can suppress deformation due to heat. Therefore, the alignment film of the present invention is useful as a member of a display device having a polarizer. More specifically, it is useful to use the alignment film of the present invention as an optical film of a display device having a polarizer and an optical film on the surface of the display element on the light emitting surface side. In particular, a display device satisfying condition 1 described later has high color rendering properties, but it is difficult to suppress rainbow unevenness. However, the alignment film of the present invention suppresses rainbow unevenness even in a display device satisfying condition 1 described later. can.
Further, since the reflected light of sunlight has a large proportion of S-polarized light, the alignment film of the present invention is a member for an automobile (a base material for a film for attaching an automobile window, a base material for a surface film of a front plate of an instrument panel, etc.). ), It is also useful as a member for housing (base material for window-pasted film).
The alignment film of the present invention is also useful as a masking film for a process of being attached to the surface of a polarizing plate, the surface of a display device, or the like.

Further, since the alignment film of the present invention can suppress deformation due to heat, it can be suitably used as a member exposed to heat.
Examples of the member exposed to heat include a member of a display device (particularly an organic EL display device), a member for an automobile, and a base material of a transparent conductive film. In particular, since the base material of the transparent conductive film is exposed to an extremely high temperature, the oriented film of the present invention is preferably used. Further, the alignment film of the present invention is extremely useful as a base material for a transparent conductive film for a touch panel used in combination with a display element.

[Transparent conductive film]
The transparent conductive film of the present invention is a transparent conductive film having a transparent conductive layer on a transparent base material, and the transparent base material is the above-mentioned alignment film of the present invention.

The transparent conductive film is exposed to a high temperature in a step of crystallizing the transparent conductive layer and a step of firing a take-out electrode made of silver paste or the like on the transparent conductive layer.
When the transparent conductive film is exposed to a high temperature, the transparent base material of the transparent conductive film may be deformed. In particular, in the transparent conductive film for a touch panel, since the transparent conductive layer is patterned, the deformation of the transparent base material tends to be promoted. However, since the transparent conductive film of the present invention uses the above-mentioned alignment film of the present invention as the transparent base material, the transparent base material (alignment film) may be deformed in the above crystallization step and firing step. Can be suppressed.

FIG. 3 is a cross-sectional view showing an embodiment of the transparent conductive 300 of the present invention.
The transparent conductive film 300 of FIG. 3 has a transparent conductive layer 200 on the alignment film 100.

<Transparent conductive layer>
Examples of the material constituting the transparent conductive layer include metal oxides. Examples of the metal oxide include tin-doped indium oxide (ITO), antimon-doped tin oxide (ATO), phosphorus-doped tin oxide (PTO), fluorine-doped tin oxide (FTO), and indium-doped zinc oxide (IZO). Of these, tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), and indium-doped zinc oxide (IZO) are preferred. In particular, tin-doped indium oxide (ITO) is preferable because it is excellent in both transparency and conductivity.

There are various methods for forming the transparent conductive layer, such as a physical vapor deposition method such as a sputtering method, a vacuum vapor deposition method, and an ion plating method, a chemical vapor deposition method, other printing methods, and a coating method. From the viewpoint of characteristics, the physical vapor deposition method and the chemical vapor deposition method are preferable, and in particular, the physical vapor deposition method that can be processed at a lower temperature is more preferable than the chemical vapor deposition method.

Normally, tin-doped indium oxide (ITO) formed by a sputtering method is amorphous, but crystallization can be promoted by heating within the heat-resistant temperature range of the alignment film, and the heating time and the like are appropriately adjusted. As a result, 50% or more can be crystallized. By this crystallization, the surface resistivity of the ITO layer can be reduced. At the same time, the adhesion strength can be improved.
The thickness of the transparent conductive layer is usually about 10 to 200 nm.

The crystallization of the transparent conductive layer may be performed either before the pattern formation of the transparent conductive layer or after the pattern forming step of the transparent conductive layer, and is crystallized in two stages before and after the pattern formation of the transparent conductive layer. It may be crystallized.
The heating temperature at the time of crystallization varies depending on the metal oxide used and the heat resistant temperature of the alignment film, but is usually 130 to 170 ° C. The heating time is usually 5 minutes to 24 hours, and may be appropriately adjusted in consideration of production efficiency and crystallinity (affecting mechanical properties, surface resistivity value, etc.). The heating method is not particularly limited and can be performed by a known method, but when ITO is used as the metal oxide, it is preferably performed using a heating furnace, an infrared lamp heater, or the like in the air.

The take-out electrode is an electrode for connecting to the patterned transparent conductive layer.
The take-out electrode can be formed by, for example, forming an electrode pattern related to wiring with a conductive material such as silver paste by screen printing or the like, and then firing (sintering by heat treatment) at a high temperature.
The heat treatment conditions for firing are usually 10 to 60 minutes at a temperature lower than the crystallization temperature of the transparent conductive layer (about 125 to 150 ° C.). The heating method is not particularly limited, and a known method can be used. Usually, it is carried out using a heating furnace, a vacuum heating furnace, an infrared lamp heater, or the like.

<Functional layer>
A functional layer may be provided between the alignment film and the transparent conductive layer.
The functional layer includes an easy-adhesion layer for improving the adhesion between the alignment film and the transparent conductive layer, an oligomer prevention layer for suppressing the precipitation of oligomer components from the alignment film, and a patterned transparent conductive layer pattern. Examples thereof include an invisible layer for obscuring the shape.

[Touch panel]
The touch panel of the present invention is a touch panel having a transparent conductive film as a constituent member, and the transparent conductive film is the above-mentioned transparent conductive film of the present invention.

Examples of the touch panel include a resistive touch panel and a capacitance type touch panel.

In the resistive touch panel 500A, for example, as shown in FIG. 4, a spacer 40 is provided so that the transparent conductive layers 100 of the pair of upper and lower transparent conductive films 300 having the transparent conductive layer 100 on the transparent base material 400 face each other. A circuit (not shown) is connected to the basic configuration arranged via the wires.
In the case of a resistive touch panel, for example, a configuration in which the transparent conductive film 300 of the present invention is used as the upper and / or lower transparent conductive film can be mentioned.

Examples of the capacitance type touch panel include a surface type and a projection type, and the projection type is often used. The projection type capacitance type touch panel is formed by connecting a circuit to a basic configuration in which an X-axis electrode and a Y-axis electrode orthogonal to the X-axis electrode are arranged via an insulator. More specifically, the basic configuration will be described in a mode in which an X-axis electrode and a Y-axis electrode are formed on separate surfaces on one transparent base material, an X-axis electrode, an insulator layer, and a Y-axis on the transparent base material. A mode in which the electrodes are formed in this order, as shown in FIG. 5, a transparent conductive film formed by forming an X-axis electrode 50 on a transparent base material 400 and a Y-axis electrode 60 on another transparent base material 400. Examples thereof include a mode in which the formed transparent conductive film is laminated via an insulator layer 70 such as an adhesive layer. Further, in addition to these basic embodiments, there is an embodiment in which another transparent base material is laminated.
In the case of the capacitive touch panel 500B, for example, a configuration in which the transparent conductive film 300 of the present invention is used as the transparent conductive film having an X-axis electrode and / or the transparent conductive film having an X-axis electrode can be mentioned.

[Display device]
Display device of the present invention, on the surface of the light emission surface side of the display device, a display device having a polarizer and one or more optical films, a light emitted in a vertical direction from the display device and the L ₁ At that time _{, the display device in which the L 1} satisfies the following condition 1 and at least one of the optical films is the alignment film of the present invention described above.
<Condition 1>
The intensity of L ₁ is measured every 1 nm. The blue wavelength range is 400 nm or more and less than 500 nm, the green wavelength range is 500 nm or more and less than 600 nm, and the red wavelength range is 600 nm or more and 780 nm or less. Maximum intensity _{B max} of the blue wavelength region of the _{L 1,} the maximum intensity _{G max} of the green wavelength region of the _{L 1,} the maximum intensity in the wavelength range of red of said _{L 1} and _{R max.}
Let _{L 1 λ B be the} wavelength indicating the B _{max , L 1} λ _{G be the} wavelength indicating the G _{max , and L 1} λ _{R be the} wavelength indicating the R _max .
The _{B max} of less than 1/2 of the intensity a wavelength showing an _{L 1} lambda minimum wavelength + alpha located in the positive direction side of the _{B B,} a wavelength showing an intensity of 1/2 or less of the _{G max} L _The maximum wavelength located on the negative side of 1 λ _{G is −α G} , and the minimum wavelength located on the positive side of _{L 1} λ _{G is + α G} , which is a wavelength showing an intensity of 1/2 or less of the _{G max.} Let _{−α R be} the maximum wavelength that is 1/2 or less of the intensity of R _max and is located on the negative side of _{L 1 λ R.}
L ₁ λ _B , L ₁ λ _G , L ₁ λ _R , + α _B , −α _G , + α _G and −α _R satisfy the following relationships (1) to (4).
+ Α _B <L ₁ λ _G (1)
L ₁ λ _B <-α _G (2)
+ Α _G <L ₁ λ _R (3)
L ₁ λ _G <-α _R (4)

FIG. 6 is a cross-sectional view showing an embodiment of the display device of the present invention. The display device 900 of FIG. 6 has a polarizer 700 and an alignment film 100 on the light emitting surface of the display element 600. Further, the display device 900 of FIG. 6 uses an organic EL display element 600A as a display element.
When the display element of the display device is a liquid crystal display element, a backlight (not shown) is required on the back surface of the liquid crystal display element.

(Condition 1)
Condition 1 is a condition indicating that the RGB (red, green, blue) spectral spectrum of the display device is sharp. Condition 1 will be described more specifically by quoting a figure.

FIG. 7 shows a display device having a polarizer and an alignment film on a three-color independent organic EL display element having a microcavity structure, and when the display element is displayed in white, it is emitted in the vertical direction from the display element. This is an example of a spectral spectrum when the intensity of the light (L _{1) to be emitted is measured every 1 nm.} The spectral spectrum of FIG. 7 is a standardized intensity of each wavelength with a maximum intensity of 100.
In FIG. 7, B _max is the maximum intensity in the blue wavelength range (400 nm or more and less than 500 nm), G _max is the maximum intensity in the green wavelength range (500 nm or more and less than 600 nm), and R _max is the red wavelength range (600 nm or more and less than 780 nm). ) Indicates the maximum strength.
Further, in FIG. 7, L ₁ λ _B indicates a wavelength indicating B _{max , L 1} λ _G indicates a wavelength indicating G _{max , and L 1} λ _R indicates a wavelength indicating R _max.
Further, in FIG. 7, + α _B is a wavelength showing an intensity of 1/2 or less of _{B max} , and indicates the minimum wavelength located on the plus direction side of _{L 1} λ _B. −α _G is a wavelength showing an intensity of 1/2 or less of _{G max} , and indicates the maximum wavelength located on the negative side of _{L 1} λ _G. + Α _G is a wavelength indicating an intensity of 1/2 or less of _{G max} , and indicates the minimum wavelength located on the positive side of _{L 1} λ _G. −α _R is a wavelength showing an intensity of 1/2 or less of _{R max} , and indicates the maximum wavelength located on the negative side of _{L 1} λ _R.
The spectroscopic spectra of FIG. 7 are all sharp in RGB spectra, and L ₁ λ _B , L ₁ λ _G , L ₁ λ _R , + α _B , −α _G , + α _G and −α _R are as follows (1). The relationship of ~ (4) is satisfied.
+ Α _B <L ₁ λ _G (1)
L ₁ λ _B <-α _G (2)
+ Α _G <L ₁ λ _R (3)
L ₁ λ _G <-α _R (4)

FIG. 8 shows a display element in a display device in which the display element is a liquid crystal display element with a color filter, the light source of the backlight is a cold cathode fluorescent lamp (CCFL), and the display element has a polarizer and an alignment film. This is an example of a spectral spectrum when the intensity of _{light (L 1} ) emitted in the vertical direction from the display element side when displayed in white is measured every 1 nm. In FIG. 8, the spectroscopic spectra of RGB are all sharp and satisfy the above relationships (1) to (4). The spectral spectrum of FIG. 8 is a standardized intensity of each wavelength with a maximum intensity of 100.

FIG. 9 shows a display device in which the display element is a liquid crystal display element with a color filter, the light source of the backlight is a white LED, and the display element has a polarizer and an alignment film on the display element, and the display element is displayed in white. In addition, it is an example of the spectral spectrum of _{the light (L 1} ) emitted in the vertical direction from the display element side. In FIG. 9, since the spectral spectrum of B (blue) is sharp and the spectral spectrum of G (green) is relatively sharp, the relationship (1) to (3) above is satisfied, but R (red). Since the spectral spectrum of is broad, the relationship (4) above is not satisfied. The spectral spectrum of FIG. 9 is a standardized intensity of each wavelength with the maximum intensity set to 100.

FIG. 10 is an example of a spectroscopic spectrum similar to the spectroscopic spectrum of FIG. The spectral spectrum of FIG. 10 is obtained in the vertical direction from the display element when the display element is displayed in white in a display device having a polarizer and an alignment film on an organic EL display element provided with a white light emitting layer and a color filter. This is an example of a spectral spectrum when the intensity of the emitted light (L _{1) is measured every 1 nm.} In the spectroscopic spectrum of FIG. 10, the spectral spectrum of B (blue) is sharp, while the spectral spectrum of G (green) on the high wavelength side and the spectral spectrum of R (red) are broad. Therefore, the spectral spectrum of FIG. 10 satisfies the relationship of (1) and (2), but does not satisfy the relationship of (3) and (4). The spectral spectrum of FIG. 10 is a standardized intensity of each wavelength with a maximum intensity of 100.

FIG. 11 shows a display device in which the display element is a liquid crystal display element with a color filter, the primary light source of the backlight is a blue LED, the secondary light source is a quantum dot, and a polarizer and an alignment film are provided on the display element. It is an example of the spectral spectrum when the intensity of _{the light (L 1} ) emitted in the vertical direction from the display element side is measured every 1 nm when the display element is displayed in white. In FIG. 11, the spectroscopic spectra of RGB are all sharp and satisfy the above relationships (1) to (4). The spectral spectrum of FIG. 11 is a standardized intensity of each wavelength with a maximum intensity of 100.

Next, the relationship between the RGB spectral spectrum and the wide color gamut will be described.
The color gamut that can be reproduced by mixing the three colors of RGB is indicated by a triangle on the CIE-xy chromaticity diagram. The triangle is formed by defining the coordinates of the vertices of each color of RGB and connecting the vertices.
When each of the RGB spectral spectra is sharp, in the CIE-xy chromaticity diagram, the apex coordinate of R has a large value of x and a small value of y, and the coordinate of the apex of G has a small value of x and a value of y. As the coordinates of the vertices of B become larger, the value of x becomes smaller and the value of y becomes smaller. That is, when each of the RGB spectral spectra is sharp, the area of the triangle connecting the vertex coordinates of each of the RGB colors in the CIE-xy chromaticity diagram becomes large, and the width of the reproducible color gamut becomes wide. And, widening the width of the color gamut leads to the improvement of the power and presence of the moving image.
Examples of the standard representing the color gamut include "ITU-R Recommendation BT.2020 (hereinafter referred to as" BT.2020 ")" and the like. ITU-R is an abbreviation for "International Telecommunication Union-Radiocommunication Sector", and ITU-R Recommendation BT. 2020 is an international standard for the color gamut of Super Hi-Vision. BT. Based on the CIE-xy chromaticity diagram represented by the following formula. When the coverage rate of 2020 is within the range described later, it is possible to easily improve the power and presence of the moving image.
<BT. Formula for 2020 coverage>
[Out of the area of the CIE-xy chromaticity diagram of the _{L 1,} BT. Area overlapping with the area of the 2020 CIE-xy chromaticity diagram / BT. Area of CIE-xy chromaticity diagram of 2020] x 100 (%)

Next, the relationship between the RGB spectral spectrum and rainbow unevenness will be described.
Patent Document 2 (Japanese Unexamined Patent Publication No. 2011-107198) suppresses rainbow unevenness by using a white LED as a backlight source and using a film having a large retardation value (Re = 3000 to 30000 nm) as an optical film. be. Then, from the description of paragraphs 0017 to 0025, FIGS. 3 and 5 of Patent Document 2, a light source having a continuous spectral spectrum (≈ the spectral spectrum has a broad shape) such as a white LED is used, and the light source is optical. When a film having a retardation value of 3000 nm or more is used, the shape of the spectral spectrum of the light source can be approximated to the shape of the wrapping line of the spectral spectrum of the light passing through the optical film, so that rainbow unevenness is suppressed. I understand what I can do. On the other hand, from the description of the above-mentioned portion of Patent Document 2, when a cold cathode fluorescent lamp having a discontinuous spectral spectrum (≈ sharp spectral spectrum) is used as the light source, the retardation value of the optical film is high. It can be understood that rainbow unevenness cannot be suppressed because the shapes of the two spectral spectra cannot be approximated even if the one having a diameter of 3000 nm or more is used.
As described above, when the RGB spectral spectrum of the light source is sharp, it is difficult to suppress rainbow unevenness by increasing the retardation value of the optical film.
On the other hand, in the present invention, since an oriented film having a retardation value of less than 400 nm, which is less affected by double refraction, is used as the optical film, the spectrum of the light source is spectroscopic even if the spectral spectrum of the light source is sharp and satisfies the condition 1. The shape of the spectrum and the shape of the spectral spectrum of the light passing through the optical film can be made substantially the same, and rainbow unevenness can be suppressed.

In the present invention, _{the spectral spectrum of L 1} is preferably the spectral spectrum when the display element is displayed in white. These spectral spectra can be measured using a spectrophotometer. At the time of measurement, the receiver of the spectrophotometer is installed so as to be perpendicular to the light emitting surface of the display device, and the viewing angle is 1 degree. Further, the light to be measured is preferably light that passes through the center of the effective display area of the display device. The spectral spectrum can be measured by, for example, a spectral radiance meter CS-2000 manufactured by Konica Minolta.
In addition, BT. "Area of CIE-xy chromaticity diagram of the _{L 1"} that is required when calculating the coverage 2020, red (R) display, green (G) display, and blue (B) display during CIE- The x and y values of the Yxy color system are measured, respectively, and the "red (R) vertex coordinates", "green (G) vertex coordinates", and "blue (B) vertex coordinates" obtained from the measurement results are measured, respectively. Can be calculated from. The x-value and y-value of the CIE-Yxy color system can be measured by, for example, a spectral radiance meter CS-2000 manufactured by Konica Minolta.

(Preferable aspect of _{L 1)}
In the display device of the present invention, _{it is preferable that the spectral spectrum of L 1} satisfies one or more of the following conditions 2 to 5. Conditions 1 to 4 mainly contribute to the expansion of the color gamut by increasing the color purity, and condition 5 mainly contributes to the expansion of the color gamut in consideration of brightness.
By satisfying the condition 2, it becomes easier to suppress the rainbow unevenness.

<Condition 2>
_{Based on the spectral spectrum of L 1} obtained in the measurement of condition 1, _{the average value B Ave} of the intensity of the spectral spectrum in the blue wavelength region, the average value G Ave of the intensity of the spectral spectrum in the green wavelength region, and the average value G _{Ave in} the red wavelength region. _{The average value R Ave} of the intensity of the spectral spectrum is calculated. In the blue wavelength range, the wavelength range in which the intensity _{of L 1} continuously exceeds _{B Ave is B p} , and in the green wavelength range, the wavelength range in which the intensity _{of L 1} continuously exceeds _{G Ave is G p} , and the red wavelength range. _{Let R p} be the wavelength range in which the intensity of L _{1 continuously exceeds R Ave.} There is only one wavelength range indicating B _p , G _p, and R _p.

The spectroscopic spectra of FIGS. 7, 9 and 11 all have one wavelength range indicating _{B p} , G _p and R _{p, and satisfy condition 2.} On the other hand, the spectroscopic spectrum of FIG. 8 _{has two wavelength ranges showing B p} , G _p, and does not satisfy the condition 2.

<Condition 3>
The + α _B , the −α _G , the + α _G, and the −α _R satisfy the following relationships (5) to (6).
+ Α _B <-α _G (5)
+ Α _G <-α _R (6)

The spectral spectra of FIGS. 7, 8 and 11 satisfy the relationships of (5) and (6), and satisfy condition 3. On the other hand, the spectral spectrum of FIG. 9 does not satisfy the relationship (6) and does not satisfy the condition 3.

<Condition 4>
The _{B max} of 1/3 or less of the intensity a wavelength showing an _{L 1} lambda beta minimum wavelength + positioned on the positive direction side of the _{B B,} a wavelength showing an intensity of 1/3 or less of the _{G max} L _The maximum wavelength located on the negative side of 1 λ _{G is −β G} , and the minimum wavelength located on the positive side of _{L 1} λ _{G is + β G} , which is a wavelength showing an intensity of 1/3 or less of the _{G max.} Let _{−β R be} the maximum wavelength that is 1/3 or less of the intensity of R _max and is located on the negative side of _{L 1 λ R.}
The + β _B , the −β _G , the + β _G, and the −β _R satisfy the following relationships (7) to (8).
+ Β _B <-β _G (7)
+ Β _G <-β _R (8)

The spectroscopic spectra of FIGS. 7, 8 and 11 all satisfy the relationship of (7) and (8), and satisfy the condition 4. On the other hand, the spectral spectrum of FIG. 9 does not satisfy the relationship (8) and does not satisfy the condition 4.

<Condition 5>
The maximum intensity of the B _max , the G _max, and the R _{max is defined} as L 1 max. B _max / L _1max , G _max / L _1max and R _max / L _1max are 0.27 or more, respectively.

In the spectroscopic spectra of FIGS. 7, 8 and 11, B _max / L _1max , G _max / L _1max and R _max / L _1max are 0.27 or more, respectively, and conditions 1-5 are satisfied. On the other hand, spectrum of Figure _9, R _{max / L 1max} are each less than 0.27, does not satisfy the condition 5.
Under condition 5, B _max / L _1max , G _max / L _1max, and R _max / L _1max are more preferably 0.30 or more, respectively.

In the spectroscopic spectrum of _{L 1} , the difference [+ β _R − ( _{−β R )] between the + β R} and the −β _R is preferably 15 to 90 nm, more preferably 30 to 85 nm, and 50. It is more preferably ~ 80 nm. Also, the + beta _G and the-beta _G difference between _{[+ β G - (- β} G)] is preferably from 20 to 80 nm, more preferably from 25 to 60 nm, it is 30~55nm Is even more preferable. Also, the + beta _B and the-beta _B and the difference that _{[+ β B - - (β} B)] is preferably 15 to 50 nm, more preferably from 20 to 40 nm, a 20~30nm Is even more preferable.

In the spectroscopic spectrum of _{L 1} , the difference [+ α _R − (−α _{R )] between the + α R} and the −α _R is preferably 10 to 70 nm, more preferably 20 to 60 nm. It is more preferably 30 to 55 nm. The difference [+ α _G − (−α _G )] between the + α _G and the −α _G is preferably 10 to 60 nm, more preferably 15 to 50 nm, and 20 to 40 nm. Is even more preferable. The difference [+ α _B − (−α _B )] between the + α _B and the −α _B is preferably 10 to 30 nm, more preferably 15 to 25 nm, and 15 to 20 nm. Is even more preferable.

Display devices with extremely sharp spectral spectra of L ₁ include a three-color independent organic EL display device, a liquid crystal display device using quantum dots for the backlight, and a liquid crystal display device using a KSF phosphor for the backlight. Can be mentioned.

(Display element)
Examples of the display element include a liquid crystal display element, an organic EL display element, an inorganic EL display element, a plasma display element, and the like. The liquid crystal display element may be an in-cell touch panel liquid crystal display element having a touch panel function inside the element.
Among these display elements, the three-color independent organic EL display element _{tends to have a sharp spectral spectrum of L 1} , and the effect of the present invention is likely to be effectively exhibited. Further, the light extraction efficiency of the organic EL display element is an issue, and in order to improve the light extraction efficiency, the organic EL element of the three-color independent system is provided with a microcavity structure. The organic EL device of the three-color independent method with a micro-cavity structure, since the spectrum of the higher L ₁ makes it caused to improve the light extraction efficiency tends to be sharp, the effect is effectively exhibited easily to the present invention.
Further, the display device is a liquid crystal display device, even when using a quantum dot or KSF phosphor as a backlight, the spectrum of the L ₁ tends to be sharp, the effect is effectively exhibited easily to the present invention.

The display element is a BT. The coverage rate of 2020 is preferably 60% or more, and more preferably 65% or more.

(Polarizer)
The polarizer is installed on the exit surface of the display element.
Examples of the polarizer include sheet-type polarizers such as polyvinyl alcohol film, polyvinyl formal film, polyvinyl acetal film, ethylene-vinyl acetate copolymerization system saponified film dyed and stretched with iodine and the like, and a large number arranged in parallel. Examples thereof include a wire grid type polarizing element made of the above metal wire, a lyotropic liquid crystal, a coated type polarizing element coated with a bicolor guest-host material, and a multilayer thin film type polarizing element. Note that these polarizers may be reflective polarizers having a function of reflecting a polarizing component that does not transmit.
Both sides of the polarizer are preferably covered with a transparent protective plate such as a plastic film or glass. It is also possible to use the alignment film of the present invention as the transparent protective plate.

The polarizer is used, for example, to impart antireflection properties in combination with a 1 / 4λ plate. When the display element is a liquid crystal display element, a rear polarizer is installed on the light incident surface side of the liquid crystal display element, and is located above the liquid crystal display element and below the liquid crystal display element. It is used to impart the function of a liquid crystal shutter by arranging the absorption axis of the rear polarizing element perpendicular to the absorption axis.

Since polarized sunglasses absorb S-polarized light in principle, the direction of the absorption axis of the polarizer of polarized sunglasses is also horizontal in principle. Therefore, it is preferable to install the display device so that the angle in the direction of the absorption axis of the polarizer is within a range of less than ± 10 ° with respect to the horizontal direction of the display device. The angle is more preferably in the range of less than ± 5 °.

(Optical film)
One or more optical films are installed on the surface of the display element on the light emitting surface side. In the display device of the present invention, the alignment film of the present invention described above is used as at least one of the optical films.

The alignment film of the present invention may be placed closer to the display element than the polarizing element, but from the viewpoint of effectively exerting the effect of the present invention, it is preferable to place the alignment film on the side opposite to the display element of the polarizer. .. This is because rainbow unevenness is likely to occur when polarized light enters and exits the alignment film.

When a plurality of optical films are present on the display element, the above-mentioned alignment film of the present invention may be used as at least one of the optical films, but it is preferable to use the above-mentioned alignment film of the present invention as all the optical films. ..

The optical film may have a functional layer on the alignment film. Examples of the functional layer include a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, an antifouling layer and the like.

(Backlight)
When the display device is a liquid crystal display device, a backlight is arranged on the back surface of the display element.
As the backlight, either an edge light type backlight or a direct type backlight can be used.
The light source of the backlight, LED, although CCFL and the like, a backlight using quantum dots as light sources, and backlight using the KSF phosphor as the light source, the spectrum of the L ₁ tends to be sharp, the The effect of the invention is likely to be effectively exerted.

A backlight using quantum dots as a light source is composed of at least a primary light source that emits primary light and a secondary light source that is composed of quantum dots that absorb primary light and emit secondary light.
When the primary light source emits primary light having a wavelength corresponding to blue, the quantum dots that are secondary light sources are the first quantum dots that absorb the primary light and emit secondary light having a wavelength corresponding to red, and the primary light. It preferably contains at least one type of second quantum dot that absorbs light and emits secondary light having a wavelength corresponding to green, and more preferably contains both the first quantum dot and the second quantum dot.

Quantum dots are semiconductor nanometer-sized fine particles that are uniquely optically and electrically due to the quantum confinement effect (quantum size effect) in which electrons and exciters are confined in small nanometer-sized crystals. It exhibits properties and is also called semiconductor nanoparticles or semiconductor nanocrystals.
Quantum dots are nanometer-sized fine particles of a semiconductor, and are not particularly limited as long as they are materials that produce a quantum confinement effect (quantum size effect).
Quantum dots may be contained in the alignment film constituting the backlight.

A backlight using a KSF phosphor as a light source is composed of a blue light emitting diode, a red phosphor, and a green and / or yellow phosphor.
In the backlight using the KSF phosphor, the blue light emitting diode emits blue light, the blue light is wavelength-converted by the green and / or yellow phosphor to emit green light and / or yellow light, and the blue light is red. The phosphor converts the wavelength to emit red light, and the blue light, the green light and / or the yellow light, and the red light are mixed to obtain white light.
As the red phosphor, it is preferable to use ^{Mn 4+ activated fluoride complex phosphor.} Mn ⁴⁺ -activated fluoride complex phosphor has the formula _K 2 _SiF 6: It is preferred that the red phosphor Mn.

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" are based on mass.

1. 1. Measurement and Evaluation The following measurements and evaluations were performed on the alignment films obtained in Examples and Comparative Examples. The results are shown in Table 1.
1-1. Measurement of retardation value A measurement sample A was prepared by cutting the central portion of the alignment film obtained in Examples and Comparative Examples into a size of 40 mm in length × 40 mm in width. Using the trade name "KOBRA-WR (measurement spot: diameter 5 mm)" manufactured by Oji Measuring Instruments Co., Ltd., the retardation value of the central portion of the measurement sample A at a wavelength of 589 nm was measured. The atmosphere at the time of measurement was a temperature of 23 ° C. ± 5 ° C. and a humidity of 50% ± 10%.

1-2. Measurement of surface orientation ratio By infrared absorption spectrum analysis in one reflection of FTIR-S polarized ATR method using FT-IR measuring device (trade name: UVIR FTS600, measurement spot: diameter 2 mm) manufactured by Bio-Rad. The absorption intensity (I ₁₃₄₀ ) at ^{1340 cm -1} of the central portion of the measurement sample A in the range of 0 to 170 degrees starting from the slow axis direction of the measurement sample A, and The absorption intensity (I ₁₄₁₀ ) at 1410 cm- ¹ was measured every 10 degrees. _Let I 1340 / I _{1410 be} the orientation parameter Y for each angle. Among the 18 measured orientation parameters Y, the maximum value was Y _max , the minimum value was Y _min , and Y _max / Y _min was the surface orientation ratio of each measurement sample A.
The absorption band of 1340 cm ^-1 _{indicates the presence of a trans body by ωCH 2} pitching vibration, and its intensity quantitatively indicates the concentration of the trans body, that is, the state in which the polyester molecule is stretched and strongly oriented. Is. On the other hand, ^{the absorption band of 1410 cm -1} is for standardizing the absorption intensity as a reference band because the absorption intensity in in-plane rotation becomes constant due to C = C expansion and contraction vibration. The atmosphere at the time of measurement was a temperature of 23 ° C. ± 5 ° C. and a humidity of 50% ± 10%.

1-3. Measurement of tensile strength For measurement sample B in which the central portion of the alignment film obtained in Examples and Comparative Examples was cut into a size of 2 mm in length × 15 cm in width, and for measurement in which the central portion was cut into a size of 15 cm in length × 2 mm in width. Sample C was prepared. According to JIS K7127: 1999, the tensile strength of the measurement sample B (lateral direction, TD direction, slow axis direction) at 23 ° C., and the measurement sample C under the conditions of a chuck-to-chuck distance of 50 mm and a tensile speed of 25 mm / min. The tensile strength at 23 ° C. (longitudinal direction, MD direction, phase advance axis direction) was measured.
If the tensile strength in both the vertical and horizontal directions is 100 MPa or more and the vertical-horizontal strength ratio is 3.0 or less, the strength and strength balance are good. A ”. On the other hand, those having a tensile strength of less than 100 MPa in either the vertical direction or the horizontal direction and / or having a vertical-horizontal strength ratio of 3.0 or more are considered to be inferior in strength and / or strength balance, and have tensile strength. The overall evaluation of was "C".

1-4. Calculation of Young's modulus The Young's modulus was calculated from the load-strain curve obtained in the measurement of "1-3" above.

1-5. Rainbow unevenness As the optical films of the display devices A to E described later, the alignment films of Examples and Comparative Examples were arranged, and the screen of the display device was displayed in color. The screen was observed from all angles while wearing polarized sunglasses, and it was evaluated whether or not a striped rainbow pattern (rainbow unevenness) was observed. As a result, those in which no rainbow unevenness was observed were designated as "A", those in which rainbow unevenness was slightly observed were designated as "B", and those in which rainbow unevenness was severely observed were designated as "C".

1-6. Thermal deformation The alignment films of Examples and Comparative Examples were heat-treated at 150 ° C. for 30 minutes. As a result, the one in which the alignment film was not deformed or the one in which the alignment film was slightly deformed but had no problem in practical use was designated as "A", and the one in which the alignment film was severely deformed and had a problem in practical use was designated as "C". It should be noted that 30 minutes at 150 ° C. is a heat treatment condition corresponding to crystallization of ITO.

2. Preparation of dispersion of birefringent particles (needle-shaped strontium carbonate particles) 2-1. Production of needle-shaped strontium carbonate particle aqueous slurry 366 g of strontium hydroxide octahydrate (special grade reagent, purity: 96% or more) was added to 3 L of pure water at a water temperature of 10 ° C., and mixed to produce water having a concentration of 5.6% by mass. An aqueous suspension of strontium oxide was prepared. DL-tartaric acid (special grade reagent, purity: 99% or more) was added to the aqueous suspension of strontium hydroxide, and the mixture was stirred and dissolved in the aqueous suspension. Then, while maintaining the liquid temperature of the aqueous suspension of strontium hydroxide at 10 ° C. and continuing stirring, a flow rate of 3.75 L / min of carbon dioxide gas was added to the aqueous suspension (22 mL per 1 g of strontium hydroxide). The aqueous suspension was blown at a flow rate of / min) until the pH of the aqueous suspension reached 7, to generate strontium carbonate particles, and then stirring was continued for another 30 minutes to obtain an aqueous suspension of strontium carbonate particles. .. The obtained aqueous suspension of strontium carbonate particles is placed in a stainless steel tank, and the aqueous suspension is heat-treated at a temperature of 80 ° C. for 24 hours to grow strontium carbonate particles in a needle shape, and then released to room temperature. It was cooled to produce an aqueous slurry of acicular strontium carbonate particles.

2-2. Surface treatment of needle-shaped strontium carbonate particles 3500 g of needle-shaped strontium carbonate particles aqueous slurry (concentration: 5.8% by mass) was put into a homomixer (TK Homomixer MarkII manufactured by Primix Corporation), and the homomixer was used. While stirring by rotating the stirring blade at a peripheral speed of 7.85 m / sec, an anhydride of polycarboxylic acid having a polyoxyalkylene group in the side chain (Marialim KM-0521, manufactured by Nichiyu Co., Ltd.) was added to the aqueous slurry. ) To 12.2 g (6 parts by mass with respect to 100 parts by mass of strontium carbonate particles) to dissolve the polymer in an aqueous slurry, followed by polyoxyethylene-stearylamine (Nymine S204, HLB = 8.0, day). 30.5 g (15 parts by mass with respect to 100 parts by mass of strontium carbonate particles) (manufactured by Oil Co., Ltd.) was added, and then stirring and mixing was continued for 1 hour. The aqueous slurry of strontium carbonate particles after stirring and mixing was sprayed onto a stainless steel plate heated to 120 to 130 ° C., and the aqueous slurry was dried to obtain fine powder of strontium carbonate.
As a result of observing the obtained strontium carbonate fine powder using an electron microscope, it was confirmed that the fine powder was a fine powder of acicular particles (average particle size: 64 nm, average aspect ratio: 2.7). .. The surface of the needle-shaped particles was analyzed by a single reflection ATR method (diamond 45 °, resolution 4 cm ^{-1) using a Fourier transform infrared spectrophotometer (FT-IR).} As a result, an infrared absorption peak caused by a polycarboxylic acid anhydride having a polyoxyalkylene group in the side chain and an infrared absorption peak caused by polyoxyethylene-stearylamine were detected.

2-3. Dispersion of Strontium Carbonate Fine Powder 0.2 g of needle-shaped strontium carbonate fine powder was added to 20 g of methylene chloride and dispersed for 5 minutes using an ultrasonic homogenizer to obtain needle-shaped strontium carbonate particles having a concentration of 1% by mass of strontium carbonate particles. A dispersion was obtained.

3. 3. Preparation of Aligned Film [Example 1]
Polyethylene terephthalate was dissolved in the needle-shaped strontium carbonate particle dispersion obtained in "1-3" above to prepare an alignment film coating liquid. The content of acicular strontium carbonate particles in the alignment film coating liquid was 5 parts by mass with respect to 100 parts by mass of polyethylene terephthalate.
The alignment film coating liquid was applied onto a glass plate using a knife coater and left in a container with low airtightness to gently evaporate the solvent. A film-like sample (film thickness: 500 μm) was peeled off from the glass plate and further dried under reduced pressure in a desiccator for about 50 hours to obtain an unstretched film of 10 cm × 10 cm.
The unstretched film is preheated at 120 ° C. for 1 minute in a biaxial stretching test device (Toyo Seiki Co., Ltd.), stretched 2.5 times in the longitudinal direction (MD direction) at 120 ° C., and then stretched 2.5 times in the transverse direction (TD direction). ) Was stretched 4.0 times to obtain an oriented film of Example 1 (30 cm × 30 cm, film thickness: 50 μm).

[Comparative Example 1]
Polyethylene terephthalate was melted at 290 ° C., extruded into a sheet through a film forming die, and cooled by being brought into close contact with a water-cooled rotary quenching drum to prepare an unstretched film. This unstretched film is preheated at 120 ° C. for 1 minute in a biaxial stretching test apparatus (Toyo Seiki Co., Ltd.), stretched 1.5 times in the longitudinal direction (MD direction) at 120 ° C., and then stretched 1.5 times in the lateral direction (TD). The film was stretched 4.5 times in the direction) to obtain an oriented film (30 cm × 30 cm, film thickness: 50 μm) of Comparative Example 1.

[Comparative Example 2]
As the alignment film of Comparative Example 2, a biaxially stretched polyethylene terephthalate film (trade name: Cosmoshine A4100, thickness 50 μm) manufactured by Toyobo Co., Ltd. was prepared.

As shown in Table 1, it can be confirmed that the oriented film of Example 1 is excellent in strength (tensile strength) and can suppress deformation and rainbow unevenness due to heat.
Although not evaluated in the table, the alignment film of Example 1 has a retardation value of less than 400 nm and a surface orientation ratio of more than 1.0 even in a measurement sample cut from a portion other than the central portion. It was 3.0 or less, and while being excellent in strength, it was able to suppress deformation and rainbow unevenness due to heat.

4. Details of Display Devices A to E 4-1. Measurement of spectral spectrum of L _{1 When} the following display devices A to E are displayed in white with a viewing angle of 1 degree using a spectrophotometer, the intensity of light (L ₁ ) emitted in the vertical direction from the display element. Was measured every 1 nm. The measurement location was the center of the effective display area of the display device. Display device 7 a spectrum of L ₁ of A, the display device 8 a spectrum of L ₁ of B, the display device C of FIG. 9 the spectrum of L _1, figure spectrum of L ₁ of the display device D 11, FIG. 12 shows the spectrum of the _{L 1} of the display device E. Table 2 shows the numerical values related to the conditions 1 to 5 calculated based on the measurement results. Further, those satisfying the conditions 1 to 5 are designated as "A", and those not satisfying the conditions are designated as "C", which are also shown in Table 2.

In the display devices A to E, the angle formed by the absorption axis of the polarizer (vibration direction of linearly polarized light) and the slow axis of the alignment film is 45 degrees.
<Display device A>
A commercially available display device having a polarizer and an alignment film on a three-color independent organic EL display element having a microcavity structure. BT. Based on the CIE-xy chromaticity diagram. Coverage rate for 2020: 77%.
<Display device B>
A commercially available display device in which the display element is a liquid crystal display element with a color filter, the light source of the backlight is a cold cathode fluorescent tube (CCFL), and a polarizer and an alignment film are provided on the display element.
<Display device C>
A commercially available display device in which the display element is a liquid crystal display element with a color filter, the light source of the backlight is a white LED, and a polarizer and an alignment film are provided on the display element. BT. Based on the CIE-xy chromaticity diagram. Coverage rate for 2020: 49%.
<Display device D (Display device 1 using quantum dots)>
A commercially available display device in which the display element is a liquid crystal display element with a color filter, the primary light source of the backlight is a blue LED, the secondary light source is a quantum dot, and a polarizer and an alignment film are provided on the display element. BT. Based on the CIE-xy chromaticity diagram. Coverage rate for 2020: 68%.
<Display device E (Display device 2 using quantum dots)>
A commercially available display device in which the display element is a liquid crystal display element with a color filter, the primary light source of the backlight is a blue LED, the secondary light source is a quantum dot, and a polarizer and an alignment film are provided on the display element. BT. Based on the CIE-xy chromaticity diagram. Coverage rate for 2020: 52%.

4-2. Realism of video The screen of the display device was set to a color video display, and the screen was observed with the polarized sunglasses removed, and the presence of the video was visually evaluated.
A: I feel a strong sense of presence.
B: I feel a sense of reality.
C: The sense of presence is unsatisfactory.

From the results in Table 2, it can be confirmed that the display devices (display devices A, B, D, E) satisfying the condition 1 are excellent in the realistic sensation of moving images because they have a wide color gamut. In particular, BT. It can be confirmed that the display devices (display devices A and D) having a coverage rate of 60% or more in 2020 have a more excellent sense of presence in the moving image.

11, 21: Polymer compound, 12, 22: Double refracting particles, 10: Core layer, 20: Surface layer, 40: Spacer, 50: X-axis electrode, 60: Y-axis electrode, 70: Insulator layer, 100: Alignment film, 200: Transparent conductive layer, 300: Transparent conductive film, 400: Transparent substrate, 500A: Resistive film type touch panel, 500B: Capacitive touch panel, 600: Display element, 700: Polarizer, 900: Display Device

Claims (9)

The alignment film has a single-layer structure and contains birefringent particles, and the alignment film has a retardation value of less than 400 nm in an arbitrary region and is calculated by the following method. An alignment film having a surface orientation ratio of more than 1.0 and 3.0 or less.
<Surface orientation ratio>
The absorption intensity (I ₁₃₄₀ ^{) of the alignment film at 1340 cm-1} in the range of 0 ° to 170 °, starting from the slow axis direction (0 degree), which is the direction in which the refractive index is the largest in the region of the alignment film. ) And the absorption intensity (I ₁₄₁₀ ^{) at 1410 cm-1} are measured every 10 degrees. _Let I 1340 / I _{1410 be} the orientation parameter Y for each angle. The maximum value among the measured 18-point orientation parameters Y is Y _max , the minimum value is Y _min , and Y _max / Y _min is the surface orientation ratio of the alignment film. The alignment film has a three-layer structure of a surface layer, a core layer, and a surface layer, and all of the three layers contain birefringent particles, and the alignment film has a retardation value of 400 nm in any region. An alignment film having a surface orientation ratio of less than 1.0 and having a surface orientation ratio of more than 1.0 and 3.0 or less calculated by the following method.
<Surface orientation ratio>
The alignment film is 1340 cm in the range of 0 to 170 degrees, starting from the slow axis direction (0 degree), which is the direction in which the refractive index is the largest in the region of the alignment film. ^-1 Absorption strength in (I ₁₃₄₀ ) And 1410 cm ^-1 Absorption strength in (I ₁₄₁₀ ) Is measured every 10 degrees. I ₁₃₄₀ / I ₁₄₁₀ Let be the orientation parameter Y for each angle. The maximum value among the measured 18-point orientation parameters Y is Y. _max , Minimum value is Y _min As Y _max / Y _min Is the surface orientation ratio of the alignment film. Of the tensile strength of 23 ° C. of the alignment film, when the slow the axis direction of the tensile strength T _L, wherein the fast axis direction of the tensile strength in the direction perpendicular to the slow axis direction is T _S, satisfy the relationship of _{T L} / T _S ≦ 3.0, the orientation film according to claim 1 or 2. Of 23 ° C. Young's modulus of the oriented film, the slow axis direction of the Young's modulus E _L, when the fast axis direction Young's modulus in the direction perpendicular to the slow axis direction is E _S, satisfy the relationship of _{E L} / E _S ≦ 1.7, the orientation film according to any one of claims 1-3. The alignment film according to any one of claims 1 to 4 , wherein the alignment film is a polyester-based film. The alignment film according to any one of claims 1 to 5 , wherein the alignment film has a width of 1000 mm or more. A transparent conductive film having a transparent conductive layer on a transparent base material, wherein the transparent base material is an alignment film according to any one of claims 1 to 6. A touch panel having a transparent conductive film as a constituent member, wherein the transparent conductive film is the transparent conductive film according to claim 7 . In a display device having a polarizer and one or more optical films on the surface of the display element on the light emitting surface side, when the light emitted in the vertical direction from the display element is L ₁ , the L ₁ is A display device that satisfies the following condition 1 and in which at least one of the optical films is the alignment film according to any one of claims 1 to 5.
<Condition 1>
The intensity of L ₁ is measured every 1 nm. The blue wavelength range is 400 nm or more and less than 500 nm, the green wavelength range is 500 nm or more and less than 600 nm, and the red wavelength range is 600 nm or more and 780 nm or less. Maximum intensity _{B max} of the blue wavelength region of the _{L 1,} the maximum intensity _{G max} of the green wavelength region of the _{L 1,} the maximum intensity in the wavelength range of red of said _{L 1} and _{R max.}
Let _{L 1 λ B be the} wavelength indicating the B _{max , L 1} λ _{G be the} wavelength indicating the G _{max , and L 1} λ _{R be the} wavelength indicating the R _max .
The _{B max} of less than 1/2 of the intensity a wavelength showing an _{L 1} lambda minimum wavelength + alpha located in the positive direction side of the _{B B,} a wavelength showing an intensity of 1/2 or less of the _{G max} L _The maximum wavelength located on the negative side of 1 λ _{G is −α G} , and the minimum wavelength located on the positive side of _{L 1} λ _{G is + α G} , which is a wavelength showing an intensity of 1/2 or less of the _{G max.} Let _{−α R be} the maximum wavelength that is 1/2 or less of the intensity of R _max and is located on the negative side of _{L 1 λ R.}
L ₁ λ _B , L ₁ λ _G , L ₁ λ _R , + α _B , −α _G , + α _G and −α _R satisfy the following relationships (1) to (4).
+ Α _B <L ₁ λ _G (1)
L ₁ λ _B <-α _G (2)
+ Α _G <L ₁ λ _R (3)
L ₁ λ _G <-α _R (4)

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