JP2017102259A - Optical rotatory film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical rotatory film having excellent optical rotatory power and suppressing a hue when viewed in an oblique direction.SOLUTION: The optical rotatory film has a first retardation layer and a second retardation layer. At least one of the first retardation layer and the second retardation layer contains a liquid crystal compound that is twist-aligned along a helical axis extending in a thickness direction of the layer. An angle formed by an in-plane slow axis of the first retardation layer on a surface on the second retardation layer side and an in-plane slow axis of the second retardation layer on a surface on the first retardation layer side is 0 to 15°. Either a retardation value in the thickness direction of the first retardation layer at a wavelength of 550 nm or a retardation value in the thickness direction of the second retardation layer at a wavelength of 550 nm is a negative value, and the other is a positive value. A value represented by (Δnd min)/(Δnd max) ranges from 0.06 to 0.8.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical rotatory film.

The optical rotatory film has a function of converting (polarizing) linearly polarized light in one direction into another direction, and is applied to various uses.
For example, Patent Document 1 discloses an optical rotatory film made of a liquid crystal compound aligned at a predetermined twist angle.

Japanese Patent Laid-Open No. 06-075115

On the other hand, in recent years, in applications in which an optical rotation film is used, not only is optical rotation excellent, but further suppression of coloring when viewed from an oblique direction is required. In addition, although it explains in full detail behind, the said optical rotation property arrange | positions an optical rotatory film between the two polarizers arrange | positioned on a backlight, front luminance (luminance when viewing the optical rotatory film from the front direction) It can be evaluated by measuring. Further, the coloring is intended to have a color difference between the front direction and the diagonal direction.
When the present inventors performed performance evaluation of a conventionally known optical rotatory film, in particular, in view of coloring when viewed from an oblique direction, the present requirement level is not satisfied, and further improvement is necessary. I know that.

  In view of the above circumstances, an object of the present invention is to provide an optical rotatory film that is excellent in optical rotatory power and is suppressed in coloring even when viewed from an oblique direction.

As a result of intensive studies on the problems of the prior art, the present inventors have found that the above problem can be solved by using a retardation layer containing a twisted liquid crystal compound.
That is, it has been found that the above object can be achieved by the following configuration.

(1) An optical rotation film having a first retardation layer and a second retardation layer,
At least one of the first retardation layer and the second retardation layer includes a liquid crystal compound that is twist-aligned along a helical axis extending along the thickness direction thereof.
The angle formed by the in-plane slow axis on the surface of the first retardation layer on the second retardation layer side and the in-plane slow axis on the surface of the second retardation layer on the first retardation layer side is 0. ~ 15 °,
One of the retardation value in the thickness direction at a wavelength of 550 nm of the first retardation layer and the retardation value in the thickness direction at a wavelength of 550 nm of the second retardation layer is a negative value, and the other is a positive value,
The product Δn1d1 of the refractive index anisotropy Δn1 of the first retardation layer measured at a wavelength of 550 nm and the thickness d1 of the first retardation layer, and the refractive index anisotropy Δn2 of the second retardation layer measured at a wavelength of 550 nm Of the product Δn2d2 of the second retardation layer and the thickness d2 of the second retardation layer is Δnd · max, and the smaller value is Δnd · min, the range of Δnd · min / Δnd · max is 0.06. An optical rotatory film that is -0.8.
(2) In the layer X containing the twisted liquid crystal compound in the first retardation layer and the second retardation layer,
Δnd / θ, which is the ratio between the product Δnd of the refractive index anisotropy Δn of the layer X measured at a wavelength of 550 nm and the thickness d of the layer X, and the twist angle θ of the liquid crystal compound is 4.1 to 6.1. The optical rotation film according to (1).
(3) The optical rotatory film according to (1) or (2), wherein both the first retardation layer and the second retardation layer include a liquid crystal compound that is twisted and aligned along a helical axis extending along a thickness direction thereof. .
(4) The twist angle of the liquid crystal compound contained in one of the first retardation layer and the second retardation layer is in the range of 67.5 ± 10 °,
The optical rotation film according to (3), wherein the twist angle of the liquid crystal compound contained in the other of the first retardation layer and the second retardation layer is in the range of 22.5 ± 10 °.
(5) The optical rotation film according to any one of (1) to (4), wherein the sum of Δn1d1 and Δn2d2 is 400 to 520 nm.
(6) The optical rotation film according to any one of (1) to (5), wherein the range of Δnd · min / Δnd · max is 0.08 to 0.50.
(7) The optical rotation film according to any one of (1) to (6), wherein the range of Δnd · min / Δnd · max is 0.10 to 0.35.

  ADVANTAGE OF THE INVENTION According to this invention, while being excellent in optical rotation property, when it visually recognizes from the diagonal direction, the optical rotation film by which coloring was suppressed can be provided.

It is an example of the schematic sectional drawing of the 1st embodiment of the optical rotation film of this invention. It is a perspective view which shows the relationship of the in-plane slow axis of each of the 1st phase difference layer and the 2nd phase difference layer in the 1st embodiment of the circularly-polarizing plate of this invention. It is an example of the schematic sectional drawing of the 2nd embodiment of the optical rotation film of this invention. It is a perspective view which shows the relationship of each in-plane slow axis of a 1st phase difference layer and a 2nd phase difference layer in the 2nd embodiment of the circularly-polarizing plate of this invention. It is the schematic at the time of arrange | positioning an optical rotatory film between two polarizers.

  The present invention will be described below. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value. First, terms used in this specification will be described.

  Re (λ) and Rth (λ) represent the in-plane retardation value at the wavelength λ and the retardation value in the thickness direction, respectively. Re (λ), Rth (λ), and Δnd are measured by AXOSCAN (manufactured by AXOMETRICS).

In addition, in this specification, when there is no special mention about a measurement wavelength, a measurement wavelength is 550 nm.
In the present specification, the relationship between angles (“orthogonal”, “parallel”) includes a range of errors allowed in the technical field to which the present invention belongs. Specifically, it means that the angle is within a range of strict angle ± 10 °, and the error from the strict angle is preferably 5 ° or less, and more preferably 3 ° or less.

Below, the suitable aspect of the optical rotation film of this invention is explained in full detail.
The optical rotatory film of the present invention is a two-layer optical rotatory film including at least one retardation layer including a twisted liquid crystal compound. One of the characteristic points is that the ratio of Δnd of the first retardation layer and Δnd of the second retardation layer included in the optical rotation film is adjusted to a predetermined range.
More specifically, there is an idea that pays attention to Rth of the retardation layer as a method for improving the viewing angle characteristics in the oblique direction, but the present inventors have found that this idea cannot be applied to an optical rotation film. It has been found that a desired effect can be obtained by adjusting the ratio of Δnd of the first retardation layer and Δnd of the second retardation layer to a predetermined range.

<First Embodiment>
Below, the 1st embodiment of the optical rotation film of this invention is demonstrated with reference to drawings. In FIG. 1, the schematic sectional drawing of the 1st embodiment of the optical rotation film of this invention is shown.
The optical rotatory film 10a includes a first retardation layer 12a and a second retardation layer 14a. The first retardation layer 12a and the second retardation layer 14a each include a liquid crystal compound that is twisted and aligned along a helical axis that extends along the thickness direction (a liquid crystal compound that is twisted and aligned with the thickness direction being a helical axis). .
Note that the twisted orientation of the liquid crystal compound means that the thickness direction of the first retardation layer 12a (or the second retardation layer 14a) is the axis (spiral axis) and the first retardation layer 12a (or the second retardation layer). It is intended that the liquid crystal compound from one main surface of the layer 14a) to the other main surface is twisted. Accordingly, the alignment direction (in-plane slow axis direction) of the liquid crystal compound varies depending on the position in the thickness direction of the first retardation layer 12a (or the second retardation layer 14a).
The first retardation layer 12a and the second retardation layer 14a preferably exhibit a chiral nematic phase having a so-called helical structure, a cholesteric phase, or the like. The liquid crystal compound will be described in detail later, but as the liquid crystal compound used in the first retardation layer 12a and the second retardation layer 14a, a liquid crystal compound exhibiting a nematic liquid crystal phase is preferably used. In addition, when forming the said phase, it is preferable to use what mixed the liquid crystal compound which shows a nematic liquid crystal phase, and the chiral agent mentioned later.

Next, the relationship between the in-plane slow axes in the first retardation layer 12a and the second retardation layer 14a will be described in detail with reference to FIG. The black arrow in each layer shown in FIG. 2 intends the in-plane slow axis.
The twist direction of the liquid crystal compound in the first retardation layer 12a and the twist direction of the liquid crystal compound in the second retardation layer 14a are the same. For example, if the twist direction of the liquid crystal compound in the first retardation layer 12a is right twist, the twist direction of the liquid crystal compound in the second retardation layer 14a is also right twist. In FIG. 2, both the first retardation layer 12a and the second retardation layer 14a show a right twist, but both may be a left twist.
Note that the twist direction of the liquid crystal compound in the first retardation layer 12a is observed from the optical retardation film 10a from the first retardation layer 12a side, as indicated by the white arrow in FIG. 2, and the first retardation layer 12a. A right twist (clockwise) or a left twist (counterclockwise) is determined on the basis of the in-plane slow axis on the surface 112a on the front side (the opposite side to the second retardation layer 14a side). Similarly to the above, the twist direction of the liquid crystal compound in the second retardation layer 14a is also observed on the optical rotation film 10a from the first retardation layer 12a side, and the front side in the second retardation layer 14a (first side) A right twist (clockwise) or a left twist (counterclockwise) is determined based on the in-plane slow axis on the surface 114a of the phase difference layer 12a side.

An in-plane slow axis on the surface 212a of the first retardation layer 12a on the second retardation layer 14a side, and an in-plane slow axis on the surface 114a of the second retardation layer 14a on the first retardation layer 12a side. The angle θ formed by In FIG. 2, the in-plane slow axis on the surface 212a of the first retardation layer 12a on the second retardation layer 14a side, and the surface 114a of the second retardation layer 14a on the first retardation layer 12a side. 2 shows a mode in which the in-plane slow axis at is parallel (that is, the angle formed is 0 °).
The preferred range of the angle θ is preferably 0 to 10 °, more preferably 0 to 5 °, in that the effect of the present invention is more excellent.

The ranges of the twist angle θ1 of the liquid crystal compound in the first retardation layer 12a and the twist angle θ2 of the liquid crystal compound in the second retardation layer 14a are not particularly limited, and vary depending on the degree of rotation of linearly polarized light. When the linearly polarized light is rotated by 90 °, the total value of the twist angle θ1 and the twist angle θ2 is preferably 60 to 120 °, and more preferably 80 to 100 °.
When linearly polarized light is rotated by 90 °, one range of the twist angle θ1 and the twist angle θ2 is preferably 20 to 115 °, and the other range is preferably 5 to 40 °. In particular, one range of the twist angle θ1 and the twist angle θ2 is more preferably 67.5 ± 10 °, and the other range is more preferably 22.5 ± 10 °.
The twist angle θ1 is determined by the in-plane slow axis on the surface 112a of the first retardation layer 12a opposite to the second retardation layer 14a, and the second retardation layer 14a of the first retardation layer 12a. The twist angle θ2 corresponds to an angle formed with the in-plane slow axis on the surface 212a on the side, and the in-plane slow axis on the surface 114a on the first retardation layer 12a side of the second retardation layer 14a, This corresponds to the angle formed by the in-plane slow axis on the surface 214a on the opposite side of the second retardation layer 14a from the first retardation layer 12a side.
The twist angle (twist angle in the alignment direction of the liquid crystal compound) is measured using an Axoscan (polarimeter) apparatus manufactured by Axometrics, using the attached apparatus analysis software.

One of the retardation value (Rth (550)) in the thickness direction at a wavelength of 550 nm of the first retardation layer 12a and the retardation value (Rth (550)) in the thickness direction at a wavelength of 550 nm of the second retardation layer 14a are negative. And the other of the retardation value in the thickness direction at the wavelength 550 nm of the first retardation layer 12a and the retardation value in the thickness direction at the wavelength 550 nm of the second retardation layer 14a is a positive value.
As described above, both the first retardation layer 12a and the second retardation layer 14a contain a liquid crystal compound, and the layer in which Rth (550) shows a positive value contains a rod-like liquid crystal compound. The layer in which Rth (550) shows a negative value preferably contains a discotic liquid crystal compound.

The ranges of Rth (550) of the first retardation layer 12a and Rth (550) of the second retardation layer 14a are not particularly limited. However, the optical rotation is more excellent and / or coloring is further suppressed (hereinafter referred to as “coloring”). The sum of the absolute value of Rth (550) of the first retardation layer 12a and the absolute value of Rth (550) of the second retardation layer 14a is 150. ˜300 nm is preferable, and 200 to 250 nm is more preferable.
In addition, in terms of more excellent effects of the present invention, one range of the absolute value of Rth (550) of the first retardation layer 12a and the absolute value of Rth (550) of the second retardation layer 14a is 5 to 100 nm. Is preferable, and 30-70 nm is more preferable.
The other range of the absolute value of Rth (550) of the first retardation layer 12a and the absolute value of Rth (550) of the second retardation layer 14a is 50 to 295 nm in that the effect of the present invention is more excellent. Is preferable, and 130-210 nm is more preferable.

The product Δn1d1 of the refractive index anisotropy Δn1 of the first retardation layer 12a measured at a wavelength of 550 nm and the thickness d1 of the first retardation layer 12a, and the refractive index difference of the second retardation layer 14a measured at a wavelength of 550 nm. Of the product Δn2d2 of the directivity Δn2 and the thickness d2 of the second retardation layer 14a, the larger value is Δnd · max, and the smaller value is Δnd · min, the range of Δnd · min / Δnd · max Is 0.06 to 0.8, and 0.08 to 0.50 is preferable and 0.10 to 0.35 is more preferable in that the effect of the present invention is more excellent.
When the range of Δnd · min / Δnd · max is less than 0.06 and more than 0.8, a desired effect cannot be obtained.
The refractive index anisotropy Δn means the refractive index anisotropy of the retardation layer.
The Δnd is measured using an Axoscan (polarimeter) apparatus manufactured by Axometrics and using the apparatus analysis software of the same company as the method for measuring the twist angle.

The range of Δn1d1 and Δn2d2 is not particularly limited, and the above-described Δnd · min / Δnd · max may be within a predetermined range. Is preferably 400 to 520 nm, and more preferably 430 to 490 nm.
The respective ranges of Δn1d1 and Δn2d2 are not particularly limited, but one of Δn1d1 and Δn2d2 is preferably from 20 to 160 nm, more preferably from 80 to 140 nm, and the other range is from 240 to 240 in that the effects of the present invention are more excellent. 500 nm is preferable and 290 to 410 nm is more preferable.

The first retardation layer 12a and the second retardation layer 14a are both layers containing a twisted liquid crystal compound, but in at least one of the layers X, the effect of the present invention is more excellent. Δnd / θ (nm /) which is the ratio of the product Δnd of the refractive index anisotropy Δn of the layer X measured at a wavelength of 550 nm and the thickness d of the layer X to the twist angle θ (°) of the liquid crystal compound in the layer X Is preferably 4.1 to 6.1, more preferably greater than 4.1 and less than 6.1, and even more preferably 4.5 to 5.7 in that the optical rotation of the optical rotation film is more excellent.
When both the first retardation layer 12a and the second retardation layer 14a are layers containing a twisted liquid crystal compound, it is preferable that at least one of the two satisfies the range of Δnd / θ. It is more preferable that both satisfy the range of Δnd / θ.

  The kind of liquid crystal compound used for forming the first retardation layer 12a and the second retardation layer 14a is not particularly limited. As the first retardation layer 12a and the second retardation layer 14a, for example, a retardation layer obtained by forming a low-molecular liquid crystal compound in a nematic orientation in a liquid crystal state and then fixing it by photocrosslinking or thermal crosslinking, or a polymer It is also possible to use a retardation layer obtained by forming a liquid crystal compound in a nematic alignment in a liquid crystal state and then cooling it to fix the alignment.

In general, liquid crystal compounds can be classified into rod-shaped types (rod-shaped liquid crystal compounds) and disk-shaped types (disk-shaped liquid crystal compounds, discotic liquid crystal compounds) based on their shapes. Furthermore, there are a low molecular type and a high molecular type, respectively. Polymer generally refers to a polymer having a degree of polymerization of 100 or more (Polymer Physics / Phase Transition Dynamics, Masao Doi, 2 pages, Iwanami Shoten, 1992). In the present invention, any liquid crystal compound can be used. Two or more rod-like liquid crystal compounds, two or more disc-like liquid crystal compounds, or a mixture of a rod-like liquid crystal compound and a disc-like liquid crystal compound may be used.
In addition, as the rod-like liquid crystal compound, for example, those described in claim 1 of JP-A No. 11-53019 and paragraphs [0026] to [0098] of JP-A-2005-289980 can be preferably used. As the discotic liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP-A-2007-108732 and paragraphs [0013] to [0108] of JP-A-2010-244038 are preferably used. However, it is not limited to these.
The first retardation layer 12a and the second retardation layer 14a can be formed by using a rod-like liquid crystal compound having a polymerizable group or a discotic liquid crystal compound having a polymerizable group, since temperature change and humidity change can be reduced. It is more preferable. The liquid crystal compound may be a mixture of two or more, and in that case, at least one of them preferably has two or more polymerizable groups.
That is, the first retardation layer 12a and the second retardation layer 14a are preferably layers formed by fixing a rod-like liquid crystal compound having a polymerizable group or a discotic liquid crystal compound having a polymerizable group by polymerization. In this case, it is no longer necessary to exhibit liquid crystallinity after forming a layer.
The kind of the polymerizable group contained in the rod-like liquid crystal compound and the discotic liquid crystal compound is not particularly limited, and a functional group capable of addition polymerization reaction is preferable, and a polymerizable ethylenically unsaturated group or a ring polymerizable group is preferable. More specifically, a (meth) acryloyl group, a vinyl group, a styryl group, an allyl group, and the like are preferable, and a (meth) acryloyl group is more preferable.

Although the optical rotatory film 10a includes at least the first retardation layer 12a and the second retardation layer 14a described above, other members may be included as long as the effects of the present invention are not impaired.
For example, the optical rotation film 10a may include an alignment film. However, as shown in FIG. 1, the first retardation layer 12a and the second retardation layer 14a are adjacent to each other, and the alignment film is substantially interposed between the first retardation layer 12a and the second retardation layer 14a. It is preferable not to have. In the case where there is substantially no alignment film between the first retardation layer 12a and the second retardation layer 14a, a covalent bond between the compounds contained in the respective retardation layers can be used, and thus the adhesion is excellent.
In this specification, “substantially no alignment film” means that a film formed only for functioning as an alignment film is not included.

Further, the optical rotation film 10a may include a support.
As the support, a known support (preferably a transparent support) can be used. For example, as a material for forming the support, a cellulose resin represented by triacetyl cellulose (hereinafter referred to as cellulose acylate) is used. Rate), thermoplastic norbornene resins (ZEONEX, ZEONOR manufactured by Nippon Zeon Co., Ltd., Arton manufactured by JSR Co., Ltd.), acrylic resins, and polyester resins can be used.
As the support, it is preferable to use a transparent support having substantially no optical anisotropy, and it is more preferable to use a transparent support having an in-plane retardation value of 0 to 10 nm at a wavelength of 550 nm.

(Manufacturing method of optical rotation film)
The optical rotation film of the present invention can be produced by various methods. One example is as follows.
First, a support is prepared, an alignment film is formed thereon, a liquid crystal compound having a polymerizable group on the alignment film surface, and a first retardation layer forming composition containing an additive such as a chiral agent as required. Apply to form a coating. This coating film is heated as desired to twist and align the liquid crystal compound in the coating film. Thereafter, the film is cooled to a temperature at which the orientation is solidified, and the coating film is subjected to a curing treatment (ultraviolet irradiation (light irradiation treatment) or heat treatment) to advance the polymerization to fix the twisted orientation, and the first phase difference Get a layer. Next, a second retardation layer forming composition containing a liquid crystal compound having a polymerizable group and optionally an additive such as a chiral agent is applied to the surface of the obtained first retardation layer to form a coating film. Then, the second retardation layer is obtained according to the same procedure as that for the first retardation layer.
The following method will be described in detail.

[Alignment film]
In the present invention, the liquid crystal compound may be aligned by applying a composition for forming a retardation layer on the surface of the alignment film. Since the alignment film has a function of defining the alignment direction of the liquid crystal compound, it is preferably used for realizing a preferred embodiment of the present invention. However, if the alignment state is fixed after the alignment of the liquid crystal compound, the alignment film plays the role and is not necessarily an essential component of the present invention.
The alignment film is an organic compound (eg, ω-tricosane) formed by rubbing treatment of an organic compound (preferably polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodgett method (LB film). Acid, dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, a method of forming an alignment film by applying an electric field, applying a magnetic field, or irradiating light (preferably polarized light) is also known.
The alignment film is preferably formed by rubbing a polymer film.

  Examples of the polymer used for forming the alignment film include, for example, methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohols and modified polymers described in paragraph [0022] of JP-A-8-338913. Examples include polyvinyl alcohol, poly (N-methylolacrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, and polycarbonate.

For example, the alignment film is formed by applying a solution containing the polymer as an alignment film forming material and an optional additive (for example, a cross-linking agent) on a support, and then drying (crosslinking) the coating film by heating. It can be formed by rubbing the film.
For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process of an LCD (liquid crystal display) can be applied. That is, a method of obtaining an alignment film by rubbing the surface of the coating film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. In general, the rubbing treatment is performed by rubbing about several times using a cloth in which fibers having a uniform length and thickness are flocked on average.

Arbitrary components, such as a liquid crystal compound and a chiral agent, may be contained in the composition for 1st phase difference layer formation and the composition for 2nd phase difference layer formation.
The description of the liquid crystal compound is as described above.
Hereinafter, typical arbitrary components will be described in detail.

[Chiral agent]
When forming the first retardation layer and the second retardation layer, if necessary, a chiral agent may be used together with the liquid crystal compound. The chiral agent is added to twist and align the liquid crystal compound. Of course, when the liquid crystal compound is an optically active compound such as having an asymmetric carbon in the molecule, the use of the chiral agent is unnecessary. is there. Note that the use of a chiral agent is not required depending on the production method or the twist angle.
The chiral agent is not particularly limited as long as it is compatible with the liquid crystal compound used in combination. Known chiral agents (for example, “Liquid Crystal Device Handbook” edited by Japan Society for the Promotion of Science 142nd Committee, Chapter 3-4-3, TN (twisted nematic), chiral agent for STN (Super Twisted Nematic), page 199, 1989 Can be used. A chiral agent generally contains an asymmetric carbon atom, but an axially asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom can also be used as the chiral agent. Examples of the axial asymmetric compound or the planar asymmetric compound include binaphthyl, helicene, paracyclophane, and derivatives thereof. Moreover, the chiral agent may have liquid crystallinity.

[Other additives]
Along with the above liquid crystal compound, a surfactant, a polymerizable monomer, a polymer, a plasticizer, and the like can be used in combination to improve the uniformity of the coating film, the strength of the retardation layer, the orientation of the liquid crystal compound, and the like. These additives are preferably compatible with the liquid crystal compound and do not inhibit the alignment.
Moreover, in order to make a liquid crystal compound into a horizontal alignment state or a vertical alignment state, you may use the additive (alignment control agent) which accelerates | stimulates horizontal alignment or vertical alignment.

  Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. For example, compounds described in paragraph numbers [0028] to [0056] in JP 2001-330725 A, compounds described in paragraph numbers [0069] to [0126] in Japanese Patent Application No. 2003-295212 Is mentioned.

  Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer and is preferably copolymerizable with the above-described polymerizable group-containing liquid crystal compound. Examples thereof include those described in paragraph numbers [0018] to [0020] in JP-A No. 2002-296423.

  The polymer used with the liquid crystal compound is preferably capable of thickening the coating solution. A cellulose ester can be mentioned as an example of a polymer. Preferable examples of the cellulose ester include those described in paragraph [0178] of JP-A No. 2000-155216.

  As the solvent used for the preparation of the first retardation layer forming composition and the second retardation layer forming composition, an organic solvent is preferable. Examples of the organic solvent include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane), esters (eg, methyl acetate, ethyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Of these, alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

  The aligned (preferably vertically aligned) liquid crystal compound is preferably fixed while maintaining the alignment state. The immobilization is preferably carried out by a polymerization reaction of a polymerizable group introduced into the liquid crystal compound using a polymerization initiator. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator, and a photopolymerization reaction is preferred.

  Application of the first retardation layer forming composition and the second retardation layer forming composition may be performed by a known method (for example, wire bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating). Law). Moreover, you may form a coating film by discharging the composition for phase difference layer formation using an inkjet apparatus.

<Second Embodiment>
Below, the 2nd embodiment of the optical rotation film of this invention is described with reference to drawings. In FIG. 3, the schematic sectional drawing of the 2nd embodiment of the optical rotation film of this invention is shown.
The optical rotatory film 10b includes a first retardation layer 12b and a second retardation layer 14b. The first retardation layer 12b is a polymer film (particularly, a polymer film that has been subjected to stretching treatment) and does not include a liquid crystal compound. The second retardation layer 14b includes a twisted liquid crystal compound with the thickness direction as a helical axis.
The optical rotatory film 10b is composed of two retardation layers in the same manner as the optical rotatory film 10a, except that a polymer film is used as the first retardation layer 12b.
Below, the structure of each layer is explained in full detail.

The first retardation layer 12b is a so-called polymer film (particularly, a polymer film that has been subjected to stretching treatment), and is a layer composed of a polymer.
Examples of the polymer film that can be used as the first retardation layer 12b include cellulose acylate films (for example, cellulose triacetate film (refractive index 1.48), cellulose diacetate film, cellulose acetate butyrate film, cellulose acetate). Propionate film), polyolefin film such as polyethylene and polypropylene, polyester film such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone film, poly (meth) acrylic film such as polymethyl methacrylate, polyurethane film, Polycarbonate film, Polysulfone film, Polyether film, Polymethylpentene film, Polyether ketone film Irumu, polystyrene films, and the like (meth) acrylonitrile based film. Specific products include, for example, a polymer having an alicyclic structure (a film of norbornene-based resin (Arton: trade name, manufactured by JSR)), amorphous polyolefin (ZEONEX: trade name, manufactured by Nippon Zeon)) The film etc. are mentioned.

The thickness of the first retardation layer 12b is not particularly limited, but is preferably 10 μm to 200 μm, more preferably 10 μm to 100 μm, and further preferably 20 μm to 90 μm.
The first retardation layer 12b may contain various additives (for example, fine particles, plasticizers, ultraviolet inhibitors, deterioration inhibitors, release agents, etc.).

  The second retardation layer 14b is a layer containing a liquid crystal compound that is twisted and oriented with the thickness direction as a helical axis, similarly to the second retardation layer 14a described above, and the aspect is as described above.

Next, the relationship between the in-plane slow axes in the first retardation layer 12b and the second retardation layer 14b will be described in detail with reference to FIG. The black arrow in each layer shown in FIG. 4 intends the in-plane slow axis.
As shown in FIG. 4, the first retardation layer 12 is composed of a polymer film, and an in-plane slow axis on the surface 112b of the first retardation layer 12b opposite to the second retardation layer 14b side. And the in-plane slow axis on the surface 212b on the second retardation layer 14b side are parallel to each other. The second retardation layer 14b is the same as the above-described second retardation layer 14a, and the in-plane slow axis on the surface 114b on the first retardation layer 12a side is opposite to the first retardation layer 12a side. An in-plane slow axis on the surface 214b of the surface forms a predetermined angle.
An in-plane slow axis on the surface 212b of the first retardation layer 12b on the second retardation layer 14b side, and an in-plane slow axis on the surface 114b of the second retardation layer 14b on the first retardation layer 12b side. Is the same as in the first embodiment and is 0 to 15 °, and the preferred range is also as described above.
The twist direction of the liquid crystal compound in the second retardation layer 14b may be right-handed or left-handed.
Note that the twist direction of the liquid crystal compound in the second retardation layer 14b is determined by observing the optical rotatory film 10b from the first retardation layer 12a side as shown by the white arrow in FIG. A right twist (clockwise) or a left twist (counterclockwise) is determined based on the in-plane slow axis on the front surface 114b on the front side (the first retardation layer 12a side).

The range of the twist angle θ3 of the liquid crystal compound in the second retardation layer 14b is not particularly limited, and varies depending on the degree of rotation of the linearly polarized light. However, when the linearly polarized light is rotated 90 ° by the optical rotation film, 60 to 120 ° is preferable.
Note that the twist angle θ3 is opposite to the in-plane slow axis on the surface 114b of the second retardation layer 14b on the first retardation layer 12b side and the first retardation layer 12b side of the second retardation layer 14b. This corresponds to the angle formed with the in-plane slow axis at the surface 214b on the side.

  One of the retardation value (Rth (550)) in the thickness direction at a wavelength of 550 nm of the first retardation layer 12b and the retardation value (Rth (550)) in the thickness direction at a wavelength of 550 nm of the second retardation layer 14b are negative. And the other of the retardation value in the thickness direction at the wavelength 550 nm of the first retardation layer 12b and the retardation value in the thickness direction at the wavelength 550 nm of the second retardation layer 14b is a positive value.

The ranges of Rth (550) of the first retardation layer 12b and Rth (550) of the second retardation layer 14b are not particularly limited, but the absolute value and the second retardation of Rth (550) of the first retardation layer 12b are not limited. The sum of absolute values of Rth (550) of the layer 14b is the absolute value of Rth (550) of the first retardation layer 12a and the absolute value of Rth (550) of the second retardation layer 14a described in the first embodiment. A range of the total value is preferred.
Further, the preferred ranges of the absolute value of Rth (550) of the first retardation layer 12b and the absolute value of Rth (550) of the second retardation layer 14b are the first phase differences described in the first embodiment. The absolute value of Rth (550) of the layer 12a and the absolute value of Rth (550) of the second retardation layer 14a are the same as the respective preferable ranges of one range and the other range.

In the second embodiment, the product Δn1d1 of the refractive index anisotropy Δn1 of the first retardation layer 12b measured at a wavelength of 550 nm and the thickness d1 of the first retardation layer 12b, and the first measured at a wavelength of 550 nm. Of the product Δn2d2 of the refractive index anisotropy Δn2 of the two retardation layer 14b and the thickness d2 of the second retardation layer 14b, the larger value is Δnd · max, and the smaller value is Δnd · min. The range of Δnd · min / Δnd · max is the same as that of the first embodiment described above.
The preferred ranges of Δn1d1 and Δn2d2 are also synonymous with those of the first embodiment.

  The second retardation layer 14b is a layer containing a liquid crystal compound that is twisted and aligned. However, the second retardation layer 14b has a refractive index anisotropy Δn measured at a wavelength of 550 nm and a second value because the effect of the present invention is more excellent. The ratio Δnd / θ, which is the ratio of the product Δnd with the thickness d of the retardation layer 14b to the twist angle θ (°) of the liquid crystal compound in the second retardation layer 14b, is preferably 4.1 to 6.1. From the point that the optical rotation of the optical rotatory film is more excellent, it is more preferably more than 4.1 and less than 6.1, and more preferably 4.5 to 5.7.

  The optical rotatory film 10b includes at least the first retardation layer 12b and the second retardation layer 14b described above, but includes other members such as an alignment film and a support as in the first embodiment. It may be.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Accordingly, the scope of the present invention should not be construed as being limited by the specific examples shown below.

<Preparation of support and formation of alignment film>
(Alkaline saponification treatment)
A commercially available cellulose acetate film Z-TAC (manufactured by FUJIFILM Corporation) was passed through a dielectric heating roll having a temperature of 60 ° C., and the film surface temperature was raised to 40 ° C. Next, an alkali solution having the composition shown below was applied to one surface of the heated film using a bar coater at a coating amount of 14 ml / m ² , and then the film was heated to 110 ° C. Next, the obtained film was transported for 10 seconds under a steam far infrared heater manufactured by Noritake Company Limited. Next, using a bar coater, 3 ml / m ^{2 of} pure water was applied onto the film surface on which the alkaline solution was applied. Next, the obtained film was repeatedly washed with a fountain coater and drained with an air knife three times, and then the film was transported to a drying zone at 70 ° C. for 10 seconds to be dried and subjected to alkali saponification treatment. A cellulose acylate film was prepared.

──────────────────────────────────
Composition of alkaline solution ──────────────────────────────────
Potassium hydroxide 4.7 parts by weight Water 15.8 parts by weight Isopropanol 63.7 parts by weight Surfactant SF-1: C ₁₄ H ₂₉ O (CH ₂ CH ₂ O) ₂₀ H 1.0 part by weight Propylene glycol 14. 8 parts by mass ──────────────────────────────────

(Preparation of alignment film)
On the long cellulose acetate film subjected to alkali saponification treatment as described above, an alignment film coating solution having the following composition was continuously applied with a # 14 wire bar. Subsequently, the film coated with the alignment film coating solution was subjected to a drying process for 60 seconds with hot air at 60 ° C., and further, a drying process for 120 seconds with warm air at 100 ° C. Subsequently, the coating film obtained on the cellulose acetate film was continuously rubbed to produce an alignment film. At this time, the longitudinal direction of the long cellulose acetate film was parallel to the transport direction, and the rotation axis of the rubbing roller was parallel to the longitudinal direction of the film.
──────────────────────────────────
Composition of alignment film coating solution ──────────────────────────────────
Modified polyvinyl alcohol 1 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Glutaraldehyde 0.5 parts by weight Photopolymerization initiator (Irgacure 2959, manufactured by BASF) 0.3 parts by weight ───────── ────────────────────────

<Example 1>
(Production of retardation layer using discotic liquid crystal compound)
On the surface of the alignment film on the cellulose acetate film prepared above, coating liquid B11 containing a discotic liquid crystal compound having the following composition was continuously applied to form a coating film. In applying the coating liquid B11, the coating amount of the coating liquid B11 was prepared and applied so that the first retardation layer having the thickness shown in Table 1 was obtained.
Subsequently, the coating film was subjected to a drying treatment at 70 ° C. for 1 minute to evaporate the solvent in the coating film, and then subjected to a heat aging treatment at 115 ° C. for 3 minutes. A uniform alignment state of the liquid crystal compound was obtained.
Thereafter, this coating film is kept at 30 ° C., and under a nitrogen atmosphere, the coating film is irradiated with ultraviolet rays (200 mJ / cm ² ) using a high-pressure mercury lamp to fix the orientation of the discotic liquid crystal compound. 1 retardation layer was produced.

──────────────────────────────────
Composition of coating liquid B11 containing discotic liquid crystal compound ――――――――――――――――――――――――――――――――――
Discotic liquid crystal compound (Compound 101) 80 parts by mass Discotic liquid crystal compound (Compound 102) 20 parts by mass Polymerizable monomer 1 10 parts by mass MegaFick F444 0.20 parts by mass Chiral agent 1 0.123 parts by mass Polymerization start Agent 1 3 parts by weight methyl ethyl ketone 196 parts by weight cyclohexanone 25 parts by weight t-butanol 25 parts by weight ――――――――――――――――――――――――――――――― ―――

(Production of retardation layer using rod-like liquid crystal compound)
On the 1st phase difference layer obtained above, the coating liquid B12 containing the rod-shaped liquid crystal compound of the following composition was apply | coated continuously, and the coating film was formed. In applying the coating liquid B12, the coating amount of the coating liquid B12 was prepared and applied so that a second retardation layer having a film thickness shown in Table 1 was obtained. The film conveyance speed (V) was 20 m / min.
Subsequently, the coating film was subjected to a heat treatment with hot air at 85 ° C. for 120 seconds for drying and removing the solvent in the coating liquid and for alignment aging of the rod-like liquid crystal compound. Subsequently, the coating film was irradiated with ultraviolet rays (300 mJ / cm ² ) at 80 ° C., the orientation of the rod-like liquid crystal compound was fixed, the second retardation layer was formed, and an optical rotation film was produced.

──────────────────────────────────
Composition of coating liquid B12 containing rod-shaped liquid crystal compound ――――――――――――――――――――――――――――――
Rod-like liquid crystal compound 201 83 parts by weight Rod-like liquid crystal compound 202 15 parts by weight Rod-like liquid crystal compound 203 2 parts by weight polyfunctional monomer A-TMMT (manufactured by Shin-Nakamura Chemical Co., Ltd.) 1 part by weight polymerization initiator IRGACURE819 (manufactured by BASF) 4 parts by weight chiral agent 1 0.136 parts by weight surfactant 2 0.05 parts by weight surfactant 3 0.01 parts by weight methyl ethyl ketone 165 parts by weight cyclohexanone 10 parts by weight ――――――――――――― ―――――――――――――――――――――

<Example 2>
According to the procedure of Example 1 (Production of retardation layer using rod-like liquid crystal compound), a first retardation layer was produced on the surface of the alignment film on the cellulose acetate film, and the produced first According to the same procedure as in Example 1, except that the second retardation layer was prepared according to the procedure of (implementation of retardation layer using discotic liquid crystal compound) performed in Example 1 on the retardation layer. An optical rotatory fill was produced.

<Example 3>
An optical rotation film was produced according to the same procedure as in Example 2, except that the thickness of the first retardation layer and the thickness of the second retardation layer were changed to the values shown in Table 1.

<Example 4>
An optical rotation film was produced according to the same procedure as in Example 1 except that the thickness of the first retardation layer and the thickness of the second retardation layer were changed to the values shown in Table 1.

<Example 5>
An optical rotation film was produced according to the same procedure as in Example 1 except that the thickness of the first retardation layer and the thickness of the second retardation layer were changed to the values shown in Table 1.

<Example 6>
An optical rotation film was produced according to the same procedure as in Example 1 except that the thickness of the first retardation layer and the thickness of the second retardation layer were changed to the values shown in Table 1.

<Example 7>
(Production of polystyrene film)
G9504 manufactured by PS Japan Co., Ltd. was dissolved in dichloromethane so as to have a solid concentration of 35% by mass to prepare a solution. The obtained solution was cast to form a cast film, and the cast film was dried. Subsequently, the cast film thus obtained was subjected to a stretching treatment (heating temperature: 110 ° C., stretching speed: 100% / min) at a stretching ratio of 100% to produce a long polystyrene film.

Next, on the obtained long polystyrene film, an alignment film was prepared according to the procedure of (preparation of alignment film) carried out in Example 1 and further carried out in Example 1 (using a rod-like liquid crystal compound). The phase difference layer was produced according to the procedure of the production of the phase difference layer, and an optical rotation film was produced.
When the alignment film was produced, the longitudinal direction of the long polystyrene film was parallel to the transport direction, and the rotation axis of the rubbing roller was 11.5 ° relative to the longitudinal direction of the film. In addition, when the polystyrene film is observed from the coating surface side of the alignment film coating solution of the polystyrene film, the angle of the rotation axis is a negative angle value when the longitudinal direction of the polystyrene film is 0 ° and clockwise (clockwise). Represented by

<Example 8>
The amount of chiral agent 1 added to coating liquid B11 containing a discotic liquid crystal compound is changed from 0.123 parts by mass to 0.152 parts by mass, and the amount of chiral agent 1 added to coating liquid B12 containing a rod-like liquid crystal compound is changed. An optical rotation film was produced according to the same procedure as in Example 1 except that the amount was changed from 0.136 parts by mass to 0.170 parts by mass.

<Example 9>
The amount of chiral agent 1 added to coating liquid B11 containing a discotic liquid crystal compound is changed from 0.123 parts by mass to 0.103 parts by mass, and the amount of chiral agent 1 added to coating liquid B12 containing a rod-like liquid crystal compound is changed. An optical rotation film was produced according to the same procedure as in Example 1 except that the amount was changed from 0.136 parts by mass to 0.113 parts by mass.

<Comparative Example 1>
(Preparation of retardation layer using discotic liquid crystal compound) is not carried out, and the thickness of the retardation layer becomes the value shown in Table 1 in (Preparation of retardation layer using rod-like liquid crystal compound). An optical rotation film was produced according to the same procedure as in Example 1 except that the change was made.

<Comparative example 2>
(Preparation of retardation layer using rod-like liquid crystal compound) is not carried out, and the thickness of the retardation layer becomes the value shown in Table 1 in (Preparation of retardation layer using discotic liquid crystal compound). An optical rotation film was produced according to the same procedure as in Example 1 except that the change was made.

<Comparative Example 3>
An optical rotation film was produced according to the same procedure as in Example 1 except that the thickness of the first retardation layer and the thickness of the second retardation layer were changed to the values shown in Table 1.

The optical rotation film produced in the said Example and comparative example was arrange | positioned between two polarizers, the evaluation sample was produced, and the following evaluation was implemented on the backlight for liquid crystal displays.
In addition, when arrange | positioning an optical rotation film between two polarizers, as shown in FIG. 5, the cellulose acetate film 20, the 1st phase difference layer 12c, and the 2nd phase difference layer 14c are included. The optical rotatory film 10c was disposed between the first polarizer 30a and the second polarizer 30b. The backlight was placed below the second polarizer 30b in FIG. 5 (on the side opposite to the first polarizer 30a side) for evaluation.
As shown in FIG. 5, the absorption axis of the first polarizer 30a (arrow in the first polarizer 30a), the absorption axis of the second polarizer 30b (arrow in the second polarizer 30b), and Are arranged so as to be orthogonal, the direction of the absorption axis of the second polarizer 30b is 0 °, and the direction of the absorption axis of the first polarizer 30a is 90 °.
Further, when the optical rotatory films of the respective examples and comparative examples are disposed between the first polarizer 30a and the second polarizer 30b, the in-plane slow axis (upper surface of the first retardation layer) is obtained. The angle of the in-plane slow axis and the in-plane slow axis of the lower surface and the angle of the in-plane slow axis of the second retardation layer (the in-plane slow axis of the upper surface and the in-plane slow axis of the lower surface) are The second polarizer 30b was arranged so as to have the values shown in Table 1 with reference to the absorption axis of the second polarizer 30b. The “in-plane slow axis on the upper surface” of the first retardation layer is intended to be the in-plane slow axis on the surface opposite to the second retardation layer, and the first retardation The “in-plane slow axis of the lower surface” of the layer means an in-plane slow axis on the surface on the second retardation layer side. Further, the “in-plane slow axis on the upper surface” of the second retardation layer is intended to be an in-plane slow axis on the surface on the first retardation layer side, and the “lower surface of the second retardation layer” The term “in-plane slow axis” means an in-plane slow axis on the surface opposite to the first retardation layer side.
Note that the above-mentioned angle is set such that the direction of the absorption axis of the second polarizer 30b is 0 ° when the evaluation sample is observed from the first polarizer 30a side (the white arrow side in FIG. 5). The rotation (counterclockwise) is represented by a positive angle value.

(Optical rotation evaluation (front luminance measurement))
In the same manner as described in paragraph 0180 of JP-A-2009-93166, using a measuring device (EZ-Contrast 160D, manufactured by ELDIM), the front luminance of the evaluation sample placed on the backlight for the liquid crystal display is measured, Evaluation was made according to the following criteria. Practically, A or B is preferable.
A: Equivalent to the front luminance of Example 1 (95% or more of the front luminance).
B: 85% or more and less than 95% of the front luminance of Example 1.
C: Less than 85% of the front luminance of Example 1.

(Measurement of color when viewed from an oblique direction (diagonal color))
Using a measuring device (EZ-Contrast 160D, manufactured by ELDIM), the color u′v ′ in the front direction and the diagonal direction of the evaluation sample arranged on the backlight for the liquid crystal display is measured, and the diagonal color difference Δu′v ′. Was calculated.
As a method of calculating Δu′v ′, first, the color in the front direction is measured. Next, the color of the diagonal direction from three directions is measured, respectively. Specifically, the three azimuths include azimuth 1 with azimuth angle 225 degrees polar angle 60 degrees, azimuth 2 with azimuth angle 270 degrees polar angle 60 degrees, and azimuth 3 with azimuth angle 315 degrees polar angle 60 degrees, The color when the optical rotatory film is observed from each of the directions is measured. Next, a color difference Δu′v′1 that is the difference between the color in the front direction and the color in the direction 1, a color difference Δu′v′2 that is the difference between the color in the front direction and the color in the direction 2, and The color difference Δu′v′3, which is the difference between the color in the front direction and the color in direction 3, was obtained, and the three color differences were arithmetically averaged to obtain the oblique color difference Δu′v ′.
Based on the value of the obtained oblique color difference Δu′v ′, the evaluation was made according to the following criteria. Practically, A or B is preferable.
A: Δu′v ′ is less than 0.01: the color difference is not noticeable.
B: Δu′v ′ is 0.01 or more and less than 0.02: The color difference is hardly noticeable visually.
C: Δu′v ′ is 0.02 or more and less than 0.3: The color difference is slightly noticeable visually.
D: Δu′v ′ is 0.03 or more: The color difference is noticeable visually.

In Table 1, “DLC” intends a discotic liquid crystal compound, and “RLC” intends a rod-like liquid crystal compound.
In addition, the “angle” column in Table 1 indicates the in-plane slow axis on the surface of the first retardation layer on the second retardation layer side and the surface of the second retardation layer on the first retardation layer side. The angle formed by the in-plane slow axis is intended.

As shown in Table 1, it was confirmed that the desired effect was obtained in the optical rotation film of the present invention.
In particular, as can be seen from the comparison between Examples 1 to 7 and Examples 8 to 9, it was confirmed that when Δnd / θ is more than 4.1 and less than 6.1, the optical rotation is more excellent.
Further, as can be seen from the comparison between Examples 1 to 4 and Examples 5 to 6, it is confirmed that coloring is further suppressed when the range of Δnd · min / Δnd · max is 0.08 to 0.50. It was done.

10a, 10b, 10c Optical rotatory films 12a, 12b, 12c First retardation layer 14a, 14b, 14c Second retardation layer

Claims (7)

An optical rotatory film having a first retardation layer and a second retardation layer,
At least one of the first retardation layer and the second retardation layer includes a liquid crystal compound that is twisted and aligned along a helical axis extending along a thickness direction thereof.
An in-plane slow axis on the surface of the first retardation layer on the second retardation layer side, and an in-plane slow axis on the surface of the second retardation layer on the first retardation layer side The formed angle is 0-15 °,
One of the retardation value in the thickness direction at a wavelength of 550 nm of the first retardation layer and the retardation value in the thickness direction at a wavelength of 550 nm of the second retardation layer is a negative value, and the other is a positive value. Yes,
The product Δn1d1 of the refractive index anisotropy Δn1 of the first retardation layer measured at a wavelength of 550 nm and the thickness d1 of the first retardation layer, and the refractive index difference of the second retardation layer measured at a wavelength of 550 nm. Of the products Δn2d2 of the directivity Δn2 and the thickness d2 of the second retardation layer, the larger value is Δnd · max, and the smaller value is Δnd · min, the range of Δnd · min / Δnd · max Is an optical rotatory film. In the layer X containing the twisted liquid crystal compound among the first retardation layer and the second retardation layer,
Δnd / θ, which is the ratio between the product Δnd of the refractive index anisotropy Δn of the layer X measured at a wavelength of 550 nm and the thickness d of the layer X, and the twist angle θ of the liquid crystal compound is 4.1 to 6 The optical rotation film according to claim 1, which is .1.   3. The optical rotatory film according to claim 1, wherein both of the first retardation layer and the second retardation layer include a liquid crystal compound twisted and aligned along a helical axis extending along a thickness direction thereof. The twist angle of the liquid crystal compound contained in one of the first retardation layer and the second retardation layer is in a range of 67.5 ± 10 °;
The optical rotation film according to claim 3, wherein the twist angle of the liquid crystal compound contained in the other layer of the first retardation layer and the second retardation layer is in the range of 22.5 ± 10 °.   The optical rotation film according to any one of claims 1 to 4, wherein a sum of the Δn1d1 and the Δn2d2 is 400 to 520 nm.   The optical rotation film according to any one of claims 1 to 5, wherein a range of Δnd · min / Δnd · max is 0.08 to 0.50.   The optical rotation film of any one of Claims 1-6 whose range of said (DELTA) nd * min / (DELTA) nd * max is 0.10-0.35.