JP2003294942A - Retardation film and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a retardation film which decreases the phase difference with the smaller measurement wavelength in a single film and which realizes λ/4 or λ/2, or λ/n (n>0) in a wide wavelength region. <P>SOLUTION: The retardation film and the method for manufacturing a retardation film satisfying λ/n (n>0) in a wide wavelength region in a single layer feature that a synthetic polymer film comprising three or more kinds of monomer components selected to satisfy specified conditions is oriented. For example, the synthetic polymer is a polycarbonate-based copolymer having bisphenol A, biscresol fluorene, styrene, and isopropenylphenol as monomer components. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a retardation film and a method for producing the same. More specifically, a retardation film useful for an optical element such as a liquid crystal display device, a light emitting device, an antiglare film, an optical recording device, and a polarization beam splitter, and a retardation film having a smaller retardation value at a wavelength of 400 to 700 nm, and a manufacturing method thereof. Regarding

[0002]

2. Description of the Related Art Retardation films are STNs for liquid crystal display devices.
(Super twisted nematic system), etc., and is used for solving problems such as color compensation and widening of viewing angle. Generally, polycarbonate, polyvinyl alcohol, polysulfone, polyether sulfone, amorphous polyolefin or the like is used as the material of the retardation film for color compensation, and a polymer in addition to the above-mentioned materials is used as the retardation film material for widening the viewing angle. Liquid crystals, alignment-cured discotic liquid crystals, and the like are used.

A quarter-wave plate which is one of retardation films can convert circularly polarized light into linearly polarized light and linearly polarized light into circularly polarized light. This is because the liquid crystal display device, in particular, the reflective liquid crystal display device with a single polarizing plate using the electrode on the back side as a reflection electrode when viewed from the observer side, and the combination of the polarizing plate and the quarter wavelength plate. And a reflection-type polarizing plate which is made of cholesteric liquid crystal or the like and reflects only one of clockwise and counterclockwise circularly polarized light.

The retardation film used in the reflection type liquid crystal display device or reflection type polarization plate of the above-mentioned one polarizing plate type has a measurement wavelength in the visible light region of 400 to 700 nm, preferably 40 nm.
It is necessary to have a function of converting linearly polarized light into circularly polarized light and converting circularly polarized light into linearly polarized light at 0 to 780 nm. If you try to realize this with one retardation film, the measurement wavelength λ = 400 to 70
0 nm, preferably 400 to 780 nm with a phase difference of λ / 4 (nm)
That is the ideal of the retardation film.

Generally, the above-mentioned retardation film materials for color compensation are used as the quarter-wave plate, and these materials have wavelength dispersion in birefringence. Generally, the birefringence (retardation) of a polymer oriented film used as a retardation film becomes larger as the measurement wavelength becomes shorter and becomes smaller as the measurement wavelength becomes longer. Therefore, with only one polymer oriented film, at the measurement wavelength λ = 400 to 700 nm, the ideal 4
It has been difficult to obtain a birefringence that becomes smaller as the measurement wavelength becomes shorter, such as a one-wave plate.

In order to obtain a film whose birefringence becomes smaller as the measurement wavelength becomes shorter, such as an ideal quarter-wave plate,
Japanese Unexamined Patent Application Publication No. 10-68816 discloses a technique in which a quarter-wave plate and a half-wave plate are attached to each other at an appropriate angle. According to this method, it is possible to obtain a quarter-wave plate and a half-wave plate having a broadband property close to ideal, but it is possible to stack two or more films while strictly adjusting the angle and phase difference. And must have an adhesive processing step. In addition, as a technique for achieving a quarter-wave plate by using one polymer film, Japanese Patent Laid-Open No. 2001-9
No. 1743, JP 2001-208913, in a wide wavelength region in the cellulose ester film, λ /
4, a technique for achieving λ / 2 is described. But,
In the cellulose ester film, hydrolysis, dimensional deformation, orientation relaxation, etc. occur due to its water absorption, and the retardation and its retardation wavelength dispersion cannot be maintained at a practical level for a long period of time. Is a member whose durability is a problem.

As a technique relating to a synthetic polymer oriented film, an oriented film made of a synthetic polymer composed of a norbornene chain and a styrene chain is disclosed in JP-A-2001-235622 and JP-A-2.
No. 001-194527. However, this is a technology based on a polymer composed of a two-component system, and it is true that λ is wider than chromatic dispersion in a normal single polymer.
Although it is possible to achieve / 4 and λ / 2, when the phase difference at the wavelength of 450 nm is set to λ / 4, the phase difference at the wavelength of 650 nm shows a low phase difference deviating from λ / 4, and vice versa. When the phase difference of λ / 4 is set to λ / 4, the phase difference at the wavelength of 450 nm shows a higher phase difference deviated. This is the same when an attempt is made to obtain a phase difference of λ / 2 in a wide band, and it is difficult to simultaneously satisfy λ / 4 and λ / 2 in both the short wavelength and the long wavelength. Furthermore, this is a synthetic polymer composed of a monomer composed of two components having a norbornene chain and a styrene chain, and the design of a broadband retarder made of a polymer composed of a monomer of three component system or more is not performed at all. I haven't been. Others include International Publication Number WO00 / 267
Japanese Patent Publication No. 05 discloses a technology relating to a polymer oriented film mainly composed of polycarbonate. However, regarding a retardation film having a broader band property, which is designed by a synthetic polymer composed of three or more component monomers, Not listed. Further, Japanese Patent Application Laid-Open No. 2001-42121 describes a retardation film composed of one polymer blend film composed of polyphenylene oxide and polystyrene. However, there is no specific description about a retardation film having a wider wavelength retardation wavelength dispersion characteristic.

[0008]

As described above, in JP-A-10-68816, by laminating two or more polymer films, λ / 4 or λ / 2 in a wide retardation region.
It is described that the above can be achieved. However, for example, in order to obtain λ / 4 or λ / 2 in a region where the retardation is wide with two or more polymer films, it is necessary to laminate them while strictly adjusting the angle and retardation of the two or more films. is there.

On the other hand, a λ / 4 plate or a λ / 2 plate made of one polymer film has also been proposed. However, there are almost no practically used films that have excellent retardance change due to excellent weather resistance and have a retardation of λ / 4 or λ / 2 in a wide wavelength range.

In the polymer film, 3
There is no known technique for obtaining a wavelength dispersion in retardation of λ / 4 or λ / 2 in a wider region in a synthetic polymer oriented film composed of monomers of component system or higher.

A main object of the present invention is to provide a near-ideal retardation film having a wide band of retardation of λ / 4 or λ / 2 by using one polymer film. is there.

Another object of the present invention is to provide a novel manufacturing method for manufacturing a retardation film having high weather resistance and practicality and having an ideal broad band property.

[0013]

In order to solve the above-mentioned problems, the present inventor diligently studied a polymer material or the like as a retardation film and found that the orientation of a synthetic polymer composed of at least three kinds of monomer components. Single layer of film (1 sheet)
Of the retardation film, wherein the retardation film has a wavelength
The phase differences at 450 nm, 550 nm, and 650 nm are expressed by the following formulas (5) and (6) R (450) <R (550) <R (650) (5) L = [((450/550) -R (450) / R (550)) ² + ((650/550) -R (650) / R (550)) ² ] ^1/2 <0.1 (6) (In the formula, R (450), R (550), R ( 650) is each wavelength 45
The present invention succeeded in providing a retardation film satisfying the in-plane retardation of the polymer oriented film at 0 nm, 550 nm and 650 nm.

That is, the present invention provides the following [1] to [8].
I was able to achieve more. [1] A method for producing a retardation film satisfying λ / n (n> 0) in a wide wavelength region in a single layer, which is selected so as to satisfy the following conditions (i) and (ii): A method for producing a retardation film, which comprises orienting a synthetic polymer film comprising three kinds of monomer components. (I) Two of the above-mentioned monomer components are polymers P _ab substantially composed of the monomer components.
And Q _cd both show positive refractive index anisotropy, and the polymer X _ef composed of other monomer components has negative refractive index anisotropy. (Ii) When the phase difference wavelength dispersion values of P _ab and Q _cd are (a, b) and (c, d), respectively, the phase difference wavelength dispersion value (e, f) of the polymer X _ef is expressed by the following formula ( 1) or (2)
Meet (650 / 550-b) / (450 / 550-a)> (650 / 550-f) / (450 / 550-e)> (650 / 550-d) / (450 / 550-c) (1) (650 / 550-b) / (450 / 550-a) <(650 / 550-f) / (450 / 550-e) <(650 / 550-d) / (450 / 550-c) (2) (Here, the phase difference wavelength dispersion values (a, b) (c, d) and (e, f) have wavelengths of 450 nm, 550 nm and 650 n.
The in-plane retardation of the retardation film at m is R (45
0), R (550), R (650)
(450) / R (550), R (650) / R (55
0)) is shown. )

[2] A method for producing a retardation film satisfying λ / n (n> 0) in a wide wavelength region with a single layer, selected so as to satisfy the following conditions (iii) and (iv) A method for producing a retardation film, which comprises orienting a film of a synthetic polymer composed of at least three types of monomer components thus prepared. (Iii) Two of the above-mentioned monomer components are polymers P ′ _ab and Q ′ _cd , which are substantially composed of the monomer components, respectively, and both of them show negative refractive index anisotropy, The refractive index anisotropy of the constituted polymer X ′ _ef is positive. (Iv)
When the retardation wavelength dispersion values of P ′ _ab and Q ′ _cd are (a ′, b ′) and (c ′, d ′), the retardation wavelength dispersion values of polymer X ′ _ef (e ′, f) ') Satisfies the following expression (3) or (4). (650 / 550-b ') / (450 / 550-a')> (650 / 550-f ') / (450 / 550-e')> (650 / 550-d ') / (450/55 0 -c ') (3) (650 / 550-b') / (450 / 550-a ') <(650 / 550-f') / (450 / 550-e ') <(650 / 550-d' ) / (450 / 550-c ') (4) (where, the phase difference wavelength dispersion value (a', b ') (c',
d ') and (e', f ') have wavelengths of 450 nm and 550
(R (450) / R (550), R (650) / R, where R (450), R (550), and R (650) are in-plane retardations of the retardation film at nm and 650 nm, respectively.
(550)) is shown. )

[3] The method for producing a retardation film according to the above [1] or [2], wherein one of the at least three kinds of monomer components has a fluorene ring.

[4] The method for producing a retardation film according to any one of the above [1] to [3], wherein the synthetic polymer is polycarbonate.

[5] A retardation film in which a synthetic polymer film comprising at least three kinds of monomer components is oriented, and the retardation film is a single layer and has a wavelength of 450 n.
A retardation film having a retardation at m, 550 nm and 650 nm satisfying the following formulas (5) and (6). R (450) <R (550) <R (650) (5) L = [((450/550) -R (450) / R (550)) ² + ((650/550) -R (650) / R (550)) ² ] ^1/2 <0.1 (6) (where R (450), R (550), R (650)
Are wavelengths of 450 nm, 550 nm, and 650 nm, respectively.
Is the in-plane retardation of the retardation film in

[6] The retardation film of the above [5], wherein one of the at least three kinds of monomer components has a fluorene ring.

[7] The retardation film of the above [5] or [6], wherein the synthetic polymer is polycarbonate.

[8] A circularly polarizing film comprising a polarizing film and the retardation film of [5] above.

As a result of earnest research, the present inventor succeeded in producing a retardation film having a wide band property such as λ / 4 or λ / 2 in a wide wavelength region by searching for a material for a polymer film. . The retardation wavelength dispersion of a retardation film composed of one polymer film is considered to be due to the optical anisotropy of the monomers constituting the polymer, and in the polymer orientation film composed of at least three types of monomer components, the component By selecting the chromatic dispersion value of the polymer which is substantially composed of the monomer units, it becomes possible to control the chromatic dispersion in the retardation, and one retardation film having a wider band can be obtained. . That is, the retardation wavelength dispersion characteristics of the retardation film can be controlled by selecting at least three-component monomers in consideration of the optical anisotropy of the polymer forming the retardation film, and an ideal broadband retardation film. Can be obtained.

As a result, in the liquid crystal display device, conventionally, at least two retardation films were laminated for use in order to have a wide band property, whereas one retardation film of the present invention was used. It has become possible to use it, and it has become possible to perform color display equivalent to that of two or more retardation films with one retardation film. Furthermore, the strict adjustment of the angle when using two or more polymer films, and the bonding process became unnecessary. Thus, the retardation film of the present invention can achieve a wide band property such as λ / 4 or λ / 2 in a wide wavelength region with one sheet.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the present invention is directed to a single-layer synthetic polymer oriented film, which has a wavelength-independent λ / 4 plate and a λ /
In the process of seeking to obtain two plates, we succeeded in providing one synthetic polymer oriented film having a phase retardation smaller as the wavelength became shorter, and achieved the above-mentioned object, as well as having a phase difference with unprecedented characteristics. It is the one that provided the film.

Further, the present inventor has found that it is possible to satisfy the above formula (5) with one sheet of a polymer oriented film composed of two kinds of monomer components. However, according to the present invention, By using a single polymer oriented film composed of three or more types of monomer components, the retardation wavelength dispersion can be easily controlled according to the target value, and λ / 4 in a wider wavelength range. Alternatively, it is possible to find an ideal phase difference chromatic dispersion capable of achieving a wide band property such as λ / 2.

Phase difference (retardation) in the present invention
Means the phase difference value in the phase difference measurement, and the phase based on the difference in the traveling speed (refractive index) of the light in the orientation direction of the film and the direction perpendicular thereto when the light passes through the film of thickness d. It is known that it is represented by the product Δn · d of the difference Δn in the refractive index between the orientation direction and the direction perpendicular thereto and the film thickness d. Further, since the phase difference Δn · d is proportional to the birefringence Δn if the films are the same, the wavelength dispersion (wavelength dependence) of the phase difference can be expressed by the wavelength dispersion (wavelength dependence) of the birefringence Δn.

The orientation of the synthetic polymer oriented film in the present invention means a state in which polymer chains are mainly arranged in a specific direction. This orientation is usually caused by stretching a film formed of a synthetic polymer.

The retardation film of the present invention comprises at least 3
A film formed of a synthetic polymer composed of various kinds of monomer components is oriented by stretching or the like. A synthetic polymer composed of at least three types of monomer components is
Included are one copolymer, one or more homopolymers or a mixture of one or more copolymers, one or more homopolymers and one or more copolymers. However, at least three types of monomer components have positive refractive index anisotropy (sometimes called optical anisotropy).
And a monomer component having negative refractive index anisotropy (optical anisotropy), and they have different retardation wavelength dispersion characteristics. By appropriately selecting three or more kinds of such monomer components, it becomes possible to control the wavelength dispersion characteristic in the retardation of the obtained retardation film (retardation wavelength dispersion characteristic).

The monomer component used here represents the structure of the minimum unit (repeating unit) necessary for forming a polymer. For example, in the case of polystyrene, the styrene skeleton (—CH ₂ (C ₆ H ₅ ) CH ₂ —) serves as a monomer component, and in the case of polyethylene terephthalate, it is formed by polycondensation of terephthalic acid or dimethyl terephthalate and ethylene glycol. Unit Unit (-O
_{CH 2 CH 2 OCOC 6 H 4} CO-) it becomes. In the case of dihydric phenols (e.g., bisphenol A) polycarbonate obtained by reacting with phosgene or carbonic acid ester, the repeating units (-OC ₆ H ₄ containing carbonic acid ester bond
C and _{(CH 3) 2 C 6 H} 4 OCO-) as monomer components.

Further, the monomer component having positive optical anisotropy means that a retardation film obtained by orienting a film formed of a polymer substantially composed of the monomer component has positive refractive index anisotropy, that is, The component of a monomer that gives a film having a positive refractive index anisotropy in the plane of the film. When the film was oriented in a uniaxial direction by stretching, the refractive index in the stretching direction was positive when it was larger than the refractive index in the direction orthogonal to the stretching direction in the film plane, and negative when it was small.

The retardation wavelength dispersion characteristic means a wide wavelength region in the retardation film, for example, 400 to 700 n.
The property (behavior) of the dispersion (change) of the phase difference with respect to m. As will be described later in detail, in the present invention, such a characteristic is represented as a retardation wavelength dispersion value by a ratio of the retardation value in the plane of the retardation film at a specific wavelength to that at another wavelength.

It is to be noted that a polymer substantially composed of a monomer component exhibits a positive or negative refractive index anisotropy when the refractive index anisotropy of an oriented film formed from such a polymer is positive or negative. There is something. The definitions of positive and negative are the same as above.

In the oriented film of synthetic polymer, the purpose of combining three or more kinds of monomer components is to control the optical anisotropy, particularly the retardation wavelength dispersion characteristic of the retardation film. For this purpose, at least one material each having a monomer component having positive optical anisotropy and a monomer component having negative optical anisotropy is required,
And at least 3 with different phase difference chromatic dispersion characteristics
A synthetic polymer composed of various types of monomer components is a material suitable for controlling the retardation wavelength dispersion of a retardation film.

As described above, in the present invention, it is important that each of the monomer components has positive or negative optical anisotropy, and that the number of monomer components is three or more. In WO00 / 26705, this is (when the refractive index in the in-plane orientation direction of the polymer oriented film is larger than the refractive index in the direction orthogonal thereto, the optical anisotropy is positive and the optical direction is the opposite direction). Although the anisotropy is negative), in the polymer oriented film, the optical anisotropy in the combination of positive and negative polymers, R (450) <R (550) <R (650) (R (450), R (55
The conditions for 0) and R (650) to be the in-plane retardation of the polymer oriented film at respective wavelengths of 450 nm, 550 nm and 650 nm are shown. In this case, it is essential that a polymer having negative optical anisotropy be present at the same time as a polymer having positive optical anisotropy (polymer having negative optical anisotropy. For, a polymer having a positive optical anisotropy is an essential condition).

Here, before describing the case of combining three or more kinds of monomer components in the present invention under specific conditions, first, the case of comprising two kinds of monomer components will be described.

A retardation film (sometimes called a polymer oriented film) using a polymer (homopolymer) P composed of a monomer component having a positive optical anisotropy and a polymer (homopolymer) Q composed of a negative monomer component. ) Shows the possible values of the phase difference wavelength dispersion value.

First, it is generally known that the birefringence Δn of a polymer blend consisting of two components, a polymer P and a polymer Q, is expressed as follows. (H. Saito and T. Inou
e, J. Pol. Sci. Part B, 25, 1629 (1987)) Δn = Δn ⁰ _p・ f _p・ Φ _p + Δn ⁰ _q・ f _q・ Φ _q + Δn _F (a) where Δn ⁰ _p : intrinsic birefringence of polymer P, Δn ⁰ _q : intrinsic birefringence of polymer Q, f _p : orientation function of polymer P, f _q : orientation function of polymer Q, Φ _p : volume of polymer P Fraction, Φ _q : volume fraction of polymer Q (= 1-Φ _p ), Δn _F : structural birefringence.
Generally, the birefringence Δn is represented by Δn = f · Δn ⁰ . Also, Δ
n can be obtained by combining dichroic infrared spectroscopy and phase difference measurement.

In the equation (a), the change in polarizability due to the electronic interaction between the polymers P and Q is completely ignored, but this assumption will be adopted below. Further, in the application of retardation film as in the present invention, since it is required to be optically transparent, the blend is preferably a compatible blend, and in this case, Δn _F is very small and neglected. You can do it.

From this, assuming that the measurement wavelengths are 450, 550 and 650 nm, the formula (a) is as follows. Δn (450) = Δn ⁰ _p (450) ・ f _p・ Φ _p + Δn ⁰ _q (450) ・ f _q・
Φ _q Δn (550) = Δn ⁰ _p (550) ・ f _p・ Φ _p + Δn ⁰ _q (550) ・ f _q・
Φ _q Δn (650) = Δn ⁰ _p (650) ・ f _p・ Φ _p + Δn ⁰ _q (650) ・ f _q・
Φ _q Here, normalization is performed at the measurement wavelength of 550 nm, and Δn (45
Taking 0) / Δn (550) and Δn (650) / Δn (550) gives the following. Δn (450) / Δn (550) = (Δn ⁰ _p (450) ・ f _p・ Φ _p + Δn ⁰ _q (4
50) ・ f _q・ Φ _q ) / (Δn ⁰ _p (550) ・ f _p・ Φ _p + Δn ⁰ _q (550)
・ F _q・ Φ _q ) Δn (650) / Δn (550) = (Δn ⁰ _p (650) ・ f _p・ Φ _p + Δn ⁰ _q (6
50) ・ f _q・ Φ _q ) / (Δn ⁰ _p (550) ・ f _p・ Φ _p + Δn ⁰ _q (550)
・ F _q · Φ _q ) Since it is a compatible blend, assuming that f _p = f _q , α = Φ _q
Assuming / Φ _p , the above two equations are as follows. Δn (450) / Δn (550) = (Δn ⁰ _p (450) + Δn ⁰ _q (450) ・ α) / (Δn ⁰ _p (550) + Δn ⁰ _q (550) ・ α) (b) Δn ( 650) / Δn (550) = (Δn ⁰ _p (650) + Δn ⁰ _q (650) ・ α) / (Δn ⁰ _p (550) + Δn ⁰ _q (550) ・ α) (c) where ( If α is deleted from the equations (b) and (c), the following equation is obtained. Δn (650) / Δn (550) = (Δn ⁰ _p (550) ・ Δn ⁰ _q (650)-Δn
⁰ _p (650) ・ Δn ⁰ _q (550)) / (Δn ⁰ _p (550) ・ Δn ⁰ _q (450)-Δn
⁰ _p (450) ・ Δn ⁰ _q (550)) × Δn (450) / Δn (550) + (Δn ⁰ _p
(650) ・ Δn ⁰ _q (450)-Δn ⁰ _p (450) ・ Δn ⁰ _q (650)) / (Δn ⁰
_p (550) ・ Δn ⁰ _q (450)-Δn ⁰ _p (450) ・ Δn ⁰ _q (550))

In this equation, Δn ⁰ _p (450), Δn ⁰ _p (55
0), Δn ⁰ _p (650), Δn ⁰ _q (450), Δn ⁰ _q (550), Δn ⁰ _q (650)
Is the intrinsic birefringence of the polymer at each wavelength and can be treated as a constant term.

Δn (650) / Δn (550) = M × Δn (450) / Δn (550) + N (d) M = (Δn ⁰ _p (550) · Δn ⁰ _q (650)-Δn ⁰ _p ( 650) ・ Δn ⁰ _q (55
0)) / (Δn ⁰ _p (550) ・ Δn ⁰ _q (450)-Δn ⁰ _p (450) ・ Δn ⁰ _q (55
0) N = (Δn ⁰ _p (650) ・ Δn ⁰ _q (450)-Δn ⁰ _p (450) ・ Δn ⁰ _q (65
0)) / (Δn ⁰ _p (550) ・ Δn ⁰ _q (450)-Δn ⁰ _p (450) ・ Δn ⁰ _q (55
0))

For M and N, the numerator and denominator are Δn ⁰ _p (550) ·
Dividing by Δn ⁰ _q (550) gives M ′ and N ′, the values of the intrinsic birefringence of each polymer normalized at the wavelength of 550 nm, Δn ⁰ _p (450) / Δn ⁰ _p (550), Δn ⁰ _p (650) / Δn ⁰ _p (550),
It can be expressed as Δn ⁰ _q (450) / Δn ⁰ _q (550) and Δn ⁰ _q (650) / Δn ⁰ _q (550). M '= [Δn ⁰ _q (650) / Δn ⁰ _q (550)-Δn ⁰ _p (650) / Δn ⁰ _p (55
0)) / [Δn ⁰ _q (450) / Δn ⁰ _q (550)-Δn ⁰ _p (450) ・ Δn ⁰ _q (55
0)] N '= [Δn ⁰ _p (650) / Δn ⁰ _p (550) ・ Δn ⁰ _q (450) / Δn ⁰ _q (550)
-Δn ⁰ _p (450) / Δn ⁰ _p (550) ・ Δn ⁰ _q (650) / Δn ⁰ _q (550)] /
(Δn ⁰ _q (450) / Δn ⁰ _q (550)-Δn ⁰ _p (450) / Δn ⁰ _p (550))

The retardation of a polymer oriented film is the difference Δ in the refractive index between the orientation direction and the direction perpendicular to it.
The wavelength dispersion value R (450), R (550), R (650) in the retardation of the oriented film by the synthetic polymer in the two-component system is represented by the product Δn · d of n and the film thickness d. ) Can be expressed as the following equation (e). R (650) / R (550) = M '× R (450) / R (550) + N' (e)

Here, M '= [R_q(650) / R_q(550)-R_p(650) / R_p(550)] / [R
_q(450) / R_q(550)-R_p(450) ・ R_q(550)) N '= (R_p(650) / R_p(550)) ・ (R_q(450) / R_q(550))-(
R_p(450) / R_p(550) ・ R_q(650) / R_q(550))] / [R_q(45
0) / R_q(550)-R_p(450) / R_p(550)) (However, R_p(450), R_p(550), R_p(650), R_q(450), R
_q(550), R_q(650) is high in polymer oriented film.
The in-plane retardation of molecule P and polymer Q is shown. ) This above formula
The boundary condition in (e) is α = Φ_q / Φ_p= (1-Φ_p) /
Φ_p(: 0 ≦ Φ_pSince the range of ≦ 1) is 0 ≦ α ≦ ∞,
Equation (b) gives Δn (450) / Δn (550).
Multiplying the numerator by the film thickness d gives R (450) / R (550)
Since it can be transformed, depending on the range of α, R (450) /
It is possible to determine the range of R (550). R (450) / R (550) = Δn (450) / Δn (550) = (Δn⁰ _p(450) + Δn⁰ _q(450) ・ α) /                                   (Δn⁰ _p(550) + Δn⁰ _q(550) / α) (b) In the above formula (b), Δn⁰ _p(450), Δn⁰ _p(550), Δn⁰ _q(Four
50), Δn⁰ _qThe phase is classified into the possible conditions of the value of (550).
The chromatic dispersion value in the difference was examined. 2 components in Table 1
Positive and negative classification of intrinsic birefringence in a system, p_RAnd q_ROf Okozeki
Person (however, p_R= Δn⁰ _p(450) / Δn⁰ _p(550) = R_p(450) / R
_p(550), q_R= Δn⁰ _q(450) / Δn⁰ _q(550) = R _q(450) / R_q(55
0). ), And R for the volume fraction α at that time
Changes in the value of (450) / R (550) are shown in Figs.
The range of R (450) / R (550) is shown. Furthermore, R (450) / R (55
For the range of (0),
Axis R (650) / R (550), Horizontal axis R (450) / R (550)
11 shows.

[0045]

[Table 1]

(However, p_R= Δn⁰ _p(450) / Δn⁰ _p(550) = R_p
(450) / R_p(550), q_R= Δn⁰ _q(450) / Δn⁰ _q(550) = R_q(45
0) / R_q(550) ) As a specific example, in case of Table 1, the optical anisotropy of the polymer is
Positive and positive combination, case5: Optical anisotropy of polymer
Two combinations of positive and negative sex will be described.

In case 1, the optical anisotropy of the polymers P and Q is positive and positive. R (450) / R (550) of polymer P and Q
When p _R > q _R , the magnitude relation of R is (45) for the volume fraction α = Φ _q / Φ _p in the synthetic polymer composed of polymers P and Q.
The change of 0) / R (550) is shown in FIG. 1 from the above equation (b). At this time, when α = 0, it is positive (polymer P), and when α = ∞, it is also positive (polymer Q), and the optical anisotropy of the synthetic polymer is the polymer P whose optical anisotropy is positive. Since it is obtained by the combination of Q, the retardation wavelength dispersion value R (450) / R (550) changes only in the region where the optical anisotropy is positive. At this time, the region of change in R (450) / R (550) of the synthetic polymer due to the polymers P and Q is q _R <R (450) / R (550) <p _R from FIG. At this time, the locus of the equation (e) drawn is the vertical axis R (650) / R
(550), abscissa R (450) / R (550) is shown in FIG. 9, and the point on the straight line connecting the retardation wavelength dispersion values of the original polymer P and the polymer Q with a straight line It is understood that (however, q _R
<R (450) / R (550) <p _R ).

Next, in case 5 of Table 1, polymer P
The optical anisotropy of and Q is positive and negative. R of polymer P and Q (4
The relationship of 50) / R (550) is that when p _R > q _R , the polymer P
Volume fraction α = Φ _q / Φ _p in a synthetic polymer consisting of
The change of R (450) / R (550) with respect to is as shown in FIG. 5 from the above equation (b). At this time, when α = 0, it is positive (polymer P) and when α = ∞, it is negative (polymer Q), and the optical anisotropy of the synthetic polymer is positive to negative at a certain volume fraction ratio, It can be seen that it reverses from negative to positive. It can be seen from FIG. 5 that R (450) / R (550) diverges at a certain ratio α, and that the optical anisotropy is inverted before and after that ratio. From this, the range of change of R (450) / R (550) of the synthetic polymer by the polymers P and Q is R (450) / R (550) when the optical anisotropy of the synthetic polymer is positive. ) <p _R , and when the optical anisotropy is negative, R (450) / R (550) <q _R. At this time, the locus of the above equation (e) drawn is the vertical axis R (650) / R (55
0), the horizontal axis is R (450) / R (550) and is shown in FIG. 11, and points on a straight line connecting the phase difference wavelength dispersion values of the original polymer P and the polymer Q with a straight line (However, optical anisotropy: positive R (450) / R (550) <p _R , optical anisotropy: negative R
(450) / R (550) <q _R ).

In the other cases 1 to 8, the two-component system can be explained in the same manner as above.

From the above, in the case of the synthetic polymer oriented film composed of two kinds of monomer components, the possible retardation wavelength dispersion depends on the phase difference wavelength dispersion characteristics of the polymer composed of the two original monomer components. You know that it will be decided. Especially, the vertical axis R (650) / R (550) and the horizontal axis R (450) / R (55
9 to 11 shown in (0), the point on the line connecting the retardation wavelength dispersion values of the two original polymers is the retardation wavelength dispersion characteristic that the synthetic polymer oriented film can take. It became clear that there is.

In the present invention, the concept of this binary system is
Expand beyond the component system. In particular, for the sake of simplicity, the vertical axis R (650) / R (550) and the horizontal axis R (45
0) / R (550) shown in FIGS. 9 to 11 (hereinafter, plotting the phase difference chromatic dispersion value by setting this axis is called dispersion plot), and plotting the change of the phase difference chromatic dispersion value. The explanation is based on the trajectory.

From the above, in the synthetic polymer oriented film consisting of two kinds of monomer components, in the dispersion plot,
It can be seen that only points on the straight line connecting the retardation wavelength dispersion values of the polymer composed of the two original monomer units can be taken. Here, assuming that the synthetic polymer oriented film is composed of, for example, three types of monomer components, a synthetic polymer composed of two types of monomer components in which refractive index anisotropy is a combination of positive and positive or negative and negative out of three types. The phase difference chromatic dispersion value of is a point on a straight line in the dispersion plot as shown in FIG. 9 as described above. On the other hand, since only one type of monomer component is left, the range of the retardation wavelength dispersion value of the synthetic polymer oriented film composed of three types of monomer components is shown in the dispersion plot as two types of monomer components. It is a point on a straight line connecting the arbitrary point on the straight line of the retardation wavelength dispersion value obtained from the above and the point of the retardation wavelength dispersion value of the polymer composed of the remaining one kind of monomer unit.
Therefore, the possible range of the retardation wavelength dispersion value obtained with the three-component synthetic polymer is given by the area connecting the straight line and the point on the dispersion plot, that is, the point on the area represented by the surface. That is, in a synthetic polymer oriented film composed of three or more kinds of monomer components, one point on the straight line of the retardation wavelength dispersion value that can be taken by the polymer composed of two kinds of monomer units in the dispersion plot. , The phase difference wavelength dispersion value can be obtained on the straight line connecting the phase difference wavelength dispersion value of the remaining one component, and the optical anisotropy always includes the opposite sign.
As long as it is a polymer composed of different types of monomer components, the range of possible retardation wavelength dispersion characteristics is not limited to a straight line,
We show that it is possible to take in-plane regions in the scatter plot. This is a technology that makes it possible to control retardation wavelength dispersion characteristics in a wider area than in a two-component system in a synthetic polymer oriented film composed of three or more kinds of monomer components in the synthetic polymer oriented film. Is shown.

In the present invention, three or more kinds of monomers necessary for achieving a single retardation film of λ / 4, λ / 2, etc., which can be suitably used for a circularly polarizing plate or an elliptically polarizing plate. It clearly shows how to combine units.

The values of R (650) / R (550) and R (450) / R (550) taken by the ideal retardation film of λ / 4, λ / 2, etc. are 550 nm as they are at 650 nm and 450 nm. It is the value divided by. R (450) / R (550) = 450/550 = 0.8181 ... (λ / 4,
λ / 2 etc, λ / n: n> 0) R (450) / R (550) = 650/550 = 1.18181 ・ ・ ・ Synthetic polymer orientation film 1 sheet (single layer) consisting of 3 or more kinds of monomer components Therefore, in order to approach an ideal retardation film such as a λ / 4 film or a λ / 2 film, it is necessary to find a combination of polymers composed of three or more types of monomer components that can take this retardation wavelength dispersion value. Indispensable. For example, when the combination of three types of monomer components is divided by optical anisotropy, it may be positive + positive + negative or positive + negative + negative. Here, λ / 4, the conditions that the retardation wavelength dispersion value of the monomer component necessary to obtain an ideal retardation film such as λ / 2 must be satisfied,
The modeled scatter plot is shown in FIG. First, positive +
The region that can be taken by the synthetic polymer oriented film of the positive or negative + negative two-component system is shown in FIG.
As shown in 2, the phase difference wavelength dispersion value of a polymer composed of two kinds of monomer components is a point on a straight line connecting points P and Q.
At this time, the optical anisotropy of the obtained synthetic polymer oriented film matches the optical anisotropy of the monomer component. Where λ
In order to obtain an ideal retardation film of / 4, λ / 2, etc., in the dispersion plot, the ideal point I and the retardation wavelength dispersion value P and Q of each polymer composed of two types of monomer units are connected. The retardation wavelength dispersion value (point X) of the two types of monomer components and the third type of monomer component having a different optical anisotropy must exist on a straight line connecting one point on the straight line. Becomes Here, the condition that the phase difference wavelength dispersion value X point of the third type of monomer component must satisfy is that the ideal point I is a fixed point, and therefore the straight line I-P connecting the ideal point I and the point P The slope of the straight line I-X connecting the ideal points I and X is larger than the slope of I and is smaller than the slope of the straight line IQ connecting the ideal points I and Q.

Inclination of the straight line IP> Inclination of the straight line IX> Inclination of the straight line IQ (f) In the phase difference wavelength dispersion value of the polymers P, Q, and X composed of monomer components (R (450) / R (550), R (650) / R (55
0)) values are P (a, b), Q (c, d), X, respectively.
(E, f), the ideal point I is I (450/550, 650/55
Since it is given by (0), rewriting the above formula (f) gives the following formula (g) (650 / 550-b) / (450 / 550-a)> (650 / 550-f) / (450 / 550-e)> (650 / 550-d) / (450/550 -c) (g) Model In FIG. 12, the slope of the straight line I-P> the slope of the straight line I-Q is shown. , Q depending on the possible positions, the slope of the straight line I> P may be greater than the slope of the straight line IQ. In this case, the following formulas (h) and (i) may be satisfied.

Slope of straight line <Slope of straight line IX <Slope of straight line IQ (h) (650 / 550-b) / (450 / 550-a) <(650 / 550-f) / (450 / 550-e) <(650 / 550-d) / (450/550 -c) (i) In other words, it can be an ideal retardation film of λ / 4, λ / 2, etc. for three component systems or more. Is positive + when the combination of three or more types of monomer components is divided by optical anisotropy.
Positive + negative or positive + negative + negative, and the above formula
It is necessary to satisfy (g) or (i) at the same time.

The conditions will be described in detail below. (I) Two of the three monomer components are composed of the remaining third monomer component, in which the two polymers substantially composed of the monomer component each exhibit positive refractive index anisotropy. The polymer has negative refractive index anisotropy, and the wavelength dispersion value (e, f) of the polymer having negative refractive index anisotropy is represented by the following formula (1) or (2):
Exists in the area that satisfies.

(650 / 550-b) / (450 / 550-a)> (650 / 550-f) / (450 / 550-e)> (650 / 550-d) / (450/550 -c) (1) (650 / 550-b) / (450 / 550-a) <(650 / 550-f) / (450 / 550-e) <(650 / 550-d) / (450/550 -c) (2) [wherein (a, b) and (c, d) are (R in the retardation wavelength dispersion value of the polymer composed of two component monomer units having positive birefringence anisotropy) (450) / R (550), R
(650) / R (550)), and (e, f) are the retardation wavelength dispersion values (R (450) / R) of the polymer composed of the remaining components and having negative refractive index anisotropy. (550), R (650) / R (550)), where R (450), R (550), and R (650) are respectively at wavelengths of 450 nm, 550 nm, and 650 nm. It represents the in-plane retardation of the retardation film. ]

(II) Two of the three monomer components are composed of the remaining third monomer component, in which the polymer substantially composed of the monomer component exhibits negative refractive index anisotropy. Where the anisotropy of the refractive index of the polymer is positive and the wavelength dispersion value (e ', f') of the polymer having a positive refractive index anisotropy satisfies the following formula (3) or (4): Exists in.

(650 / 550-b ') / (450 / 550-a')> (650 / 550-f ') / (450 / 550-e')> (650 / 550-d ') / (4 50 / 550-c ') (3) (650 / 550-b') / (450 / 550-a ') <(650 / 550-f') / (450 / 550-e ') <(650/550 -d ') / (4 50 / 550-c') (4) [wherein (a ', b') and (c ', d') are two having positive birefringence anisotropy (R (450) / R in the retardation wavelength dispersion value of the polymer substantially composed of the monomer component of the component
(550), R (650) / R (550)), where (e ', f') is the retardation wavelength dispersion value of the polymer with negative refractive index anisotropy composed of the remaining components. (R (450) / R (550), R (650) / R (55
0)), where R (450), R (550), R (6
50) represents the in-plane retardation of the retardation film at wavelengths of 450 nm, 550 nm and 650 nm, respectively. ] When these regions are shown by a diagram based on a dispersion plot for each of these combinations, the combination of optical anisotropy is
In the case of (I) positive + positive + negative, FIG. 13 shows (II) negative + negative +
The positive case can be represented in FIG.

This is R (450) / R (550) = 450/550,
When R (450) / R (550) = 650/550 is regarded as a fixed point, in order to fill an ideal retardation film such as λ / 4 and λ / 2 with a single layer synthetic polymer, the above formula is used. It is defined in M'which is the slope of (e), that is, when the above equation (e) is viewed as a straight line passing through the ideal point as the retardation film in the dispersion plot, λ / 4, λ / 2, etc. The region where the retardation wavelength dispersion value of the ideal retardation film of
A straight line with (450) / R (550) = 450/550 and R (450) / R (550) = 650/550 as fulcrums, and by designating the range of its inclination M ', λ / 4, λ The area where the retardation wavelength dispersion value of an ideal retardation plate such as / 2 can be taken is determined. That is, in the case of a three-component system, if the monomer component in the region satisfying this condition is selected, λ
This means that a synthetic polymer capable of providing an ideal retardation film such as / 4 and λ / 2 in a single layer can be obtained.

As described above, when a synthetic polymer composed of three kinds of monomer components is used, by selecting such that the original monomer component satisfies a specific condition, a wide single-layer polymer film can be obtained. Λ / 4 in the wavelength range
Alternatively, it becomes possible to provide a retardation film that achieves λ / 2.

The combination of the optical anisotropy of the three types of monomer components is (positive, positive, negative), or
A combination of (negative, negative, positive) is possible. Where 3
When it is a component of two types, the optical anisotropy is positive 2 types and negative 1
There are two types of combinations, positive one type and negative two types, and any combination thereof may be used.

The combination of the optical anisotropy of four or more kinds of monomer components is (positive, positive, negative), or
A combination of a plurality of components of four or more types including (negative, negative, positive) is conceivable. At this time, regarding the optical anisotropy of the monomer component composed of four or more kinds, the synthetic polymer oriented film obtained by applying the above-mentioned idea has λ / 4, λ
It is also possible to find enough conditions to obtain the retardation wavelength dispersion value of an ideal retardation film such as / 2. In the case of n (n is a natural number) component, when the (n-1) component is known, It is also possible to derive a specific condition to be satisfied by the remaining one component. However, in the n-component, showing the specific condition requires showing the cases where the (n-1) component can be divided into many, which is a very complicated condition and (n-1) It is difficult to specify the retardation wavelength dispersion value of a polymer substantially composed of each monomer component of the component, and there are cases where it is not possible to form a transparent polymer film with a single component, which is difficult. There are also cases.

By the way, in the case of a synthetic polymer, a copolymer or a mixture of which the composition ratio is constant,
The phase difference wavelength dispersion value is also constant. Utilizing this fact,
In the optical anisotropy of four or more kinds of monomer components, the component having a constant composition ratio in the synthetic polymer is 1
It is regarded as a component, and a monomer component composed of four or more kinds is treated as a monomer component composed of three kinds in a pseudo manner, so that it is simply applied to a system of a monomer component composed of three kinds. For example, when the synthetic polymer is composed of four kinds of monomer components A, B, C and D, it can be considered as the following 12 cases. A specific example using this idea will be described in detail below using the first embodiment.

[0066]

[Table 2]

In Example 1, positive, negative and negative combinations are shown as the combinations of the optical anisotropies of the monomer components constituting the synthetic polymer. In this case, according to the definition of the above-mentioned monomer component, when the monomer component represents the structure of the minimum unit necessary for forming a polymer, the monomer components are [A], [B], [C] and [D]. ] Can be considered as four components. Here, in consideration of the above, the four components are treated as pseudo three component (three types) of monomer components. Here, it is practically easy to obtain a copolymer of [A] + [B] or a copolymer of [C] + [D], and which copolymer is regarded as one component. Since the results are the same, here, the pseudo three kinds of components are considered as combinations of [A], [B], and [C] + [D]. (At this time, the copolymerization ratio of [C] + [D] is made to coincide with the existing ratio of [C] and [D] present in the synthetic polymer film.) Thereby, the optical difference of the polymer [A] Positiveness,
The optical anisotropy of the polymer [B] is classified as negative, and the optical anisotropy of the styrene-isopropenylphenol copolymer [C] + [D] is classified as negative. The combination of is a combination of (negative, negative, positive).

Considering the above expressions (b) and (c), the present invention cannot be applied when the positive and negative polymers have completely equal retardation wavelength dispersion coefficients.

The above consideration is based on the above equation (a), but since this idea is very well established in an actual system as in the embodiment described later, this idea is correct in the embodiment as well. To be proven. [Regarding Synthetic Polymer] The retardation film in the present invention is an oriented film obtained by orienting a synthetic polymer film by stretching or the like. By the way, according to the study by the present inventors, TAC (triacetyl cellulose-based polymer) which is a natural polymer is considered to be useful as a retardation film, but there is a difficulty in practical weather resistance, and this weather resistance is It is difficult that the phase difference does not change while it is held.
However, in the present invention, a synthetic polymer satisfying the above relationship and composed of at least three kinds of monomer components can be used. Such synthetic polymer is
For example, a mixture of two or more polymers (blend) is 1
It may be a copolymer of more than one kind or a mixture thereof.

Since a polymer blend needs to be optically transparent, it is preferable that the mixture of two or more kinds of polymers (compatibility blend system) or each of the polymers to be used has substantially the same refractive index. Specific combinations of polymer blends include poly (methyl methacrylate) as a polymer having negative optical anisotropy and poly (vinylidene fluoride) or poly (ethylene) as a polymer having positive optical anisotropy. Oxide), poly (vinylidene fluoride-co-trifluoroethylene), poly (phenylene oxide) as a polymer having positive optical anisotropy, polystyrene having negative optical anisotropy, and poly (styrene- (Co-lauroyl maleimide),
Combination of poly (styrene-co-cyclohexylmaleimide), poly (styrene-co-phenylmaleimide), poly (styrene-co-maleic anhydride) with negative optical anisotropy and positive optical anisotropy Polycarbonate, and poly (acrylonitrile-co-butadiene) having a positive optical anisotropy and poly (acrylonitrile-co-styrene) having a negative optical anisotropy are preferably used, but are not limited thereto. Not a thing.

The copolymer may be a polymer exhibiting negative refractive index anisotropy, such as polystyrene-based polymer, polyacrylonitrile-based polymer, polymethylmethacrylate-based polymer, cellulose ester-based polymer (in which the intrinsic birefringence is positive. (Excluding some), but examples include poly (butadiene-co-polystyrene),
Examples thereof include poly (ethylene-co-polystyrene), poly (acrylonitrile-co-butadiene), and poly (acrylonitrile-co-butadiene-co-styrene).
Further, a segment having a fluorene ring as a polymer skeleton is preferable because it can be a polymer exhibiting negative optical anisotropy. For example, a polycarbonate copolymer having a fluorene ring, a polyester copolymer, a polyester carbonate copolymer, a polyarylate copolymer or the like, which has a negative intrinsic birefringence, is more preferably used. As the polymer exhibiting positive optical anisotropy, it is possible to use a polycarbonate copolymer, a polyester copolymer, a polyester carbonate copolymer, a polyarylate copolymer or the like having a positive intrinsic birefringence.

A polycarbonate copolymer produced by reacting a bisphenol with a carbonic acid ester-forming compound such as phosgene or diphenyl carbonate is excellent in transparency, heat resistance and productivity and can be particularly preferably used. The polycarbonate copolymer has the following formula (I)
A copolymer containing a structure (I) having a fluorene skeleton having a repeating unit represented by and a repeating unit represented by the following formula (II) is preferable. Further, the component (I) is preferably contained in an amount of 1 to 99 mol%.

[0073]

[Chemical 1]

In the above formula (I), R _{1 to} R ₈ are each independently selected from a hydrogen atom, a halogen atom and a hydrocarbon group having 1 to 6 carbon atoms, and X is the following formula:

[0075]

[Chemical 2]

It is

[0077]

[Chemical 3]

In the above formula (II), R _{9 to} R ₁₆ are each independently a hydrogen atom, a halogen atom and a carbon number of 1 to 22.
And a Y is selected from the following formula group.

[0079]

[Chemical 4]

Here, R _{17 to} R ₁₉ , R ₂₁ , and R ₂₂ in Y are each independently a hydrogen atom, a halogen atom, and a carbon number of 1 to 1.
22 hydrocarbon groups, R ₂₀ and R ₂₃ are selected from hydrocarbon groups having 1 to 20 carbon atoms, and Ar is selected from aryl groups having 6 to 10 carbon atoms.

The above synthetic polymer can be produced by a known method. For the polycarbonate copolymer, a method by polycondensation of a dihydroxy compound and phosgene, a melt polycondensation method and the like are preferably used.

Specific examples of the above-mentioned synthetic polymer include, for example, preferably polycarbonates containing bisphenol having a fluorene ring as a polymer skeleton as a monomer component. Further, as the polycarbonate, a polycarbonate containing styrene or a styrene derivative as a monomer component and containing a block component can be exemplified.

Further, in the retardation film of the present invention, a polymer modifier such as a heat resistance stabilizer, an antioxidant, an ultraviolet absorber, a light stabilizer, a transparent nucleating agent, a permanent antistatic agent, an optical brightener is used. It may be present in the film at the same time.

The retardation film of the present invention is preferably transparent and has a haze value of 5% or less and a total light transmittance of 85.
% Or more is preferable. The glass transition temperature is preferably 90 ° C or higher.

[Method for producing retardation film] The method for producing the retardation film of the present invention will be described. In the present invention, the above-mentioned synthetic polymer is subjected to a film forming step of forming a film, and then subjected to a stretching step of increasing orientation in a plane direction by a stretching operation or the like.

In the film forming step, any existing film forming method may be used as a forming method. For example, a solvent casting method of dissolving in a solvent and casting, an extrusion molding method of kneading in a solid state to form an extruded film from a die, a calendering method of kneading in a solid state and then forming a film with a calender roll, a press forming a film with a press, etc. A molding method and the like can be mentioned. Among these, the solvent casting method, which is excellent in film thickness accuracy, is particularly preferable. As the solvent in the solvent casting method, methylene chloride, dioxolane and the like are used, but the solvent is not limited thereto. Although there is no limitation on the thickness of the film after film formation, it is preferably 20 to 300 μm, more preferably 50 to 150 μm from the viewpoint of handling and cost of the film. The addition of the specific compound in the solvent casting is preferably performed at the time of forming the film forming solution from the viewpoint of uniform mixing.

The film obtained above is then usually uniaxially stretched in a stretching step. As the stretching method, any known method may be used. Examples thereof include a tenter stretching method and a roll-to-roll compression stretching method. From the viewpoint of the controllability of the refractive index in the thickness direction and the uniformity of the in-plane retardation of the film, the method of uniaxially stretching by the inter-roll stretching method or the tenter stretching method is preferable. The stretching ratio is appropriately determined so as to obtain the desired retardation. (For example, in the case of polycarbonate, the stretching temperature is usually 150.
˜170 ° C., and the draw ratio is 1.01 to 1.10 times. The stretching temperature of the polymer film for obtaining the retardation film is approximately ± 50 ° C. around the glass transition temperature of the polymer, and the stretching ratio is 1.01 to 4.0 times. ) In the retardation film, for the purpose of improving stretchability, phthalic acid esters such as dimethyl phthalate and dibutyl phthalate, which are known plasticizers, phosphoric acid esters such as tributyl phosphate, aliphatic dibasic esters, and glycerin. Derivatives, glycol derivatives and the like may be contained, and the present invention is not limited to these. The organic solvent used during the film formation described above may be left in the film and stretched. The organic solvent is preferably 1 to 20% by weight based on the polymer solid content.

[Retardation Film, Circularly Polarized Film, Elliptical Polarized Film, and Liquid Crystal Display Element or Optical Device Using the Same] Thus, according to the present invention, an ideal broadband retardation film is provided. Such a retardation film is a good 1 / n wavelength plate (λ / n plate) having a small wavelength dependence, particularly preferably a 1/4 wavelength film having a film (orientation film) in which a synthetic polymer is oriented. Plate (λ
/ 4 plate) or a half-wave plate (λ / 2 plate), but for use as a λ / 4 plate, 100 nm ≦ R (550) ≦ 180 nm, λ For use as a 1/2 plate, it is preferable that 220 ≦ R (550) ≦ 330 nm.

The retardation film of the present invention can be used as a wide band λ / 4 plate and a wide band λ / 2 plate in one piece, and therefore, the phase difference wavelength dispersion is represented by the following formula: 0.60 <R (450) / R (550) <0.97 and 1.01 <R (650) / R
(550) <1.40, more preferably 0.65 <R (450) / R (550) <0.92 and 1.03 <R (650) / R
(550) <1.30 More preferably 0.70 <R (450) / R (550) <0.87 and 1.04 <R (650) / R
It is preferably within the range of (550) <1.25.

Further, in particular, the retardation film can be obtained in accordance with the above concept, and R (450) /
The area that the two points of R (550) and R (650) / R (550) satisfy is L = [((450/550) -R (450) / R (550)) ² + ((650/550) -R (650) /
R (550)) ² ] ^1/2 <0.1 is close to the ideal. More preferably L = [((450/550) -R (450) / R (550)) ² + ((650/550) -R (650) /
R (550)) ² ] ^1/2 <0.07 More preferably L = [((450/550) -R (450) / R (550)) ² + ((650/550) -R (650) /
R (550)) ² ] ^1/2 <0.05.

When the retardation film of the present invention is used as a λ / 4 plate, for example, when it is used in a reflection type liquid crystal display device in which only one polarizing plate is used and the back electrode also serves as a reflection electrode, It is possible to obtain a reflection type display device having excellent characteristics. It is also possible to use this retardation film on the back surface side of an observer of the guest-host type liquid crystal layer. In these cases, the role of the retardation film is
It is to convert linearly polarized light into circularly polarized light and circularly polarized light into linearly polarized light in the visible light region, and the retardation film of the present invention can satisfy such an object.

Thus, as one of the preferred embodiments of the present invention, a reflection type liquid crystal having a liquid crystal cell including a liquid crystal layer between two substrates having a polarizing plate, a λ / 4 plate and a transparent electrode in this order. A display device, wherein the λ / 4 plate is a retardation film composed of a single polymer oriented film,
The phase difference at wavelengths of 450 nm and 550 nm is expressed by the following formula (5),
(6) R (450) <R (550) <R (650) (5) L = [((450/550) -R (450) / R (550)) ² + ((650/550) -R (650) / R (550)) ² ] ^1/2 <0.1 (6) [wherein R (450), R (550) and R (650) are wavelengths 4 respectively.
It is the in-plane retardation of the polymer oriented film at 50 nm, 550 nm and 650 nm. ] And R (550) is 100-18
Provided is a reflective liquid crystal display device using a retardation film having a thickness of 0 nm.

Further, it can be similarly used as an element for converting circularly polarized light into linearly polarized light of a reflection type polarizing plate composed of cholesteric liquid crystal or the like which reflects only one of the left and right circularly polarized light.

The retardation film of the present invention may be laminated with a polarizing film via an adhesive layer or an adhesive layer to form a circularly polarizing film or an elliptically polarizing film, or the retardation film may be coated with any material. The wet heat durability may be improved or the solvent resistance may be improved.

The retardation film of the present invention has been particularly developed for obtaining an ideal λ / 4 plate or λ / 2 plate having a smaller birefringence as the wavelength becomes shorter with one polymer oriented film. However, since a polymer orientation film having a smaller birefringence as the wavelength becomes shorter is newly provided, the retardation films of the present invention are laminated, or the retardation film of the present invention and another optical film (transparent film, By laminating a transparent conductive film, a retardation film, a polarizing plate, an optical compensation plate, etc.), a wider variety of types can be produced, such as producing ideal λ / 4 plates or λ / 2 plates in a wider wavelength range. It is possible to obtain a retardation film or an optical film suitable for the above-mentioned application.

The K value is an index of the three-dimensional refractive index anisotropy of the retardation film, but it also changes depending on the R value and the film thickness.
Furthermore, the optimum value differs depending on the application. Here, K
Nz which is another index of three-dimensional refractive index anisotropy instead of the value
When a preferable range is described as = (nx-nz) / (nx-ny), it is preferably 0.3 to 1.5 in the case of a retardation film such as a λ / 4 plate and a λ / 2 plate. Particularly when Nz = 0.5, the retardation hardly changes even when the angle of incidence on the retardation film changes from front incidence. Two
If it is an axially stretched product, it is preferably -100 to 100.
As the three-dimensional refractive index nx, ny, nz of Nz, the one used in the calculation of the K value is used.

Further, by using such a retardation film in a liquid crystal display device, particularly in a single polarizing plate type reflection type liquid crystal display device, a display device excellent in image quality can be obtained.
The reflection type liquid crystal display device includes a polarizing plate, a retardation film, a substrate with a transparent electrode, a liquid crystal layer, a substrate with a scattering / reflection electrode, a polarizing plate, a scattering plate, a retardation film, and a transparent electrode. Examples include a substrate, a liquid crystal layer, a substrate with a specular reflection electrode, a polarizing plate, a retardation film, a substrate with a transparent electrode, a liquid crystal layer, a substrate with a transparent electrode, and a reflection layer. . Further, the λ / 4 plate can be used in a liquid crystal display device having both a transmission type and a reflection type. Examples of the structure of the liquid crystal display device include a polarizing plate, a retardation film, a substrate with a transparent electrode, a liquid crystal layer, a substrate with a reflective / transmissive electrode, a retardation film, a polarizing plate, and a backlight system. Further, for example, in a reflective polarizing plate which is made of cholesteric liquid crystal and reflects only left or right circularly polarized light, when used as an element for converting circularly polarized light into linearly polarized light, excellent linearly polarized light in a wide band can be obtained.

Furthermore, the retardation film of the present invention is
It can also be used as a λ / 4 plate used in an optical head of an optical recording device. In particular, since such a retardation film can give a retardation of a quarter wavelength to multiple wavelengths, it contributes to reduce the number of retardation plates in an optical head using a plurality of laser light sources. be able to.

As the optical member in a liquid crystal projector or the like, for example, the retardation film of the present invention may be used for a polarization conversion element, a polarization beam splitter or the like such as a λ / 4 plate or a λ / 2 plate.

Further, the organic or inorganic electroluminescence element which is a light emitting element uses a metal electrode on the back side of the light emitting layer. Since this metal electrode reflects light, the contrast is lowered in the presence of outside light. , The visibility is significantly reduced. In order to prevent this, a circular polarizing film by combining the retardation film of the present invention with a polarizing film,
You may use as an antireflection film. Since this circularly polarizing film uses the retardation film of the present invention capable of having a retardation of ¼ wavelength in a wide wavelength range of visible light, reflection can be prevented in a broadband wavelength,
It is possible to provide an element which is less colored in reflected light and has excellent visibility. It may also be used as a touch panel,
It may be used for CRT and PDP.

Furthermore, the retardation film of the present invention can be used as an image quality improving film for improving the color tone of a transmissive liquid crystal display device and enlarging the viewing angle. Examples of the liquid crystal display device include a twist nematic mode, a vertical alignment mode, an OCB (Optically compensated bend) alignment mode, and an in-plane switching mode.

The retardation film of the present invention is
For example, two or more liquid crystal display devices may be used depending on the purpose. Further, it may be used at the same time as an optical compensation film such as another retardation film or a viewing angle widening film (for example, a viewing angle widening film in which a discotic liquid crystal or polymer liquid crystal layer is oriented in the film thickness direction). Such,). Furthermore, as a liquid crystal display device, a ferroelectric liquid crystal,
The retardation film of the present invention may be used for an antiferroelectric liquid crystal.

[0103]

EXAMPLES Material property values and the like described in this specification are obtained by the following evaluation methods. (1) Measurement of R value The retardation value R, which is the product of the birefringence Δn and the film thickness d, is the spectroscopic ellipsometer, trade name “JASCO M-” manufactured by JASCO Corporation.
150 Polarization Modulated Spectroscopic Ellipsome
ter ”. R is measured with the incident light ray and the surface of the film perpendicular to each other, and R = Δn
* D = (nx-ny) * d. The unit of R value is nm
Is. nx, ny, and nz are defined here as follows. nx: Refractive index in the main stretching direction in the film plane ny: Refractive index in the direction orthogonal to the main stretching direction in the film plane nz: Refractive index in the normal direction to the film surface (the main stretching direction is uniaxial stretching Means the direction of stretching so as to increase the degree of orientation in the case of biaxial stretching, and refers to the orientation direction of the polymer main chain in terms of chemical structure.) (2) Total light transmittance And haze measurement The haze was measured with an integrating sphere type light transmittance measuring device in accordance with Japanese Industrial Standard JIS K 7105 "Plastic Optical Property Test Method". As the evaluation device, a color difference / turbidity measuring instrument manufactured by Nippon Denshoku Industries Co., Ltd .: trade name “COH-300A” was used. (3) Measurement of polymer copolymerization ratio Proton NMR of JEOL brand name "JNM-alpha600"
It was measured by. Particularly in the case of a copolymer of bisphenol A and biscresolfluorene, deuterated benzene was used as a solvent, and the calculation was made from the proton intensity ratio of each methyl group. (4) Polymerization Method of Polymer Monomer components (repeating units) constituting the polycarbonate used in Examples and Reference Examples, polystyrene, polyisopropenylphenol, and styrene-
The monomer component (repeating unit) constituting the isopropenylphenol copolymer is shown.

[0104]

[Chemical 5]

[0105]

[Chemical 6]

[0106]

[Chemical 7]

[0107]

[Chemical 8]

[0108]

[Chemical 9]

The styrene-isopropenylphenol copolymer [C] + [D] having the above structure has a molar ratio of styrene: isopropenyl = 50: 50 (mol%).
And the composition ratio was almost the same as the charged amount of the monomer.

Next, the monomer component having the above structure
[A] and [B] and styrene-isopropenylphenol copolymer [C] + [D] were respectively added to X: Y: Z (mol%, X +
Y + Z = 100, where X, Y, and Z represent the molar ratio of the monomer components, and Z is the total amount [C] of the polystyrene monomer component [C] and the polyisopropenyl monomer component [D] used during the synthesis. ] + [D] is treated as the amount of the monomer component) and the copolymerization is performed by the phosgene method.
A polycarbonate-polystyrene copolymer was obtained. The composition ratio of the obtained copolymer was equivalent to the charged amount of the monomer.

[Example 1] Monomer components [A] and [B] and a monomer component (styrene-isopropenylphenol copolymer) [C] + [D] were added to X: Y; Z = 40: 30: Thirty
A polycarbonate-polystyrene copolymer copolymerized at a ratio of (mol%) was used. This polycarbonate-
Polystyrene copolymer dissolved in methylene chloride 18
A wt% dope was created. A cast film was prepared from this dope solution and stretched at a temperature of 175 ° C. in a width-free uniaxial manner at a ratio of 2.6 to obtain a retardation film.

It was confirmed that the shorter the wavelength at the measurement wavelength of this film, the smaller the retardation, the largest in-plane refractive index in the stretching direction, and the positive refractive index anisotropy. Incidentally, R (550) = 137.3 nm, R (4
50) / R (550) and R (650) / R (550)
Were 0.82 and 1.14, respectively. Further, in the following formula, the inequality sign is satisfied. L = [((450/550) -R (450) / R (550)) ² + ((650/550) -R (650) /
R (550)) ² ) ^1/2 = 0.04 <0.1

The combination of the polymers is negative + negative + positive as follows. Monomer component [A] Optical anisotropy: positive monomer component [B] Optical anisotropy: negative monomer component [C] + [D] Optical anisotropy: negative Furthermore, retardation wavelength dispersion equation (4) is satisfied. . (650 / 550-b ') / (450 / 550-a') <(650 / 550-f ') / (450 / 550-e') <(650 / 550-d ') / (450 / 550- c ') (4) Monomer component [C] + [D] -0.88 <Monomer component [A] -0.85
<Monomer component [B] -0.73

Accordingly, when a synthetic polymer composed of three or more kinds of monomer components satisfying a specific condition is used, when a synthetic polymer composed of two kinds of monomer components having positive and negative optical anisotropy is used. It was confirmed that a retardation film having a broadband property of λ / 4 or λ / 2, which cannot be achieved, can be obtained.

As a weather resistance test of this retardation film, 10% humidity at 60 ° C. and 90% humidity DRY was used.
Although it was held for 00 hours, no change in retardation or change in retardation wavelength dispersion characteristic was observed, and it could be confirmed that the film can be used as a retardation film having good weather resistance.

A circularly polarizing plate was prepared by laminating this retardation film with the slow axis of the retardation film inclined by 45 ° with respect to the transmission axis of the polarizing plate.
In the visible region, extremely good circular polarization characteristics were obtained.

[Example 2] Monomer components [A] and [B], and a styrene-isopropenylphenol copolymer [C] were used.
A polycarbonate-polystyrene copolymer copolymerized at a ratio of X: Y; Z = 40: 30: 30 (mol%) was used. This polycarbonate-polystyrene copolymer was dissolved in methylene chloride to prepare an 18 wt% dope. A cast film was prepared from this dope solution and stretched at a temperature of 175 ° C. in a width-free uniaxial direction at a magnification of 1.5 to obtain a retardation film.

It was confirmed that the shorter the wavelength at the measurement wavelength, the smaller the retardation of this film, the largest in-plane refractive index in the stretching direction, and the positive refractive index anisotropy. In addition, R (550) = 18.5 nm, R (45
The values of 0) / R (550) and R (650) / R (550) were 0.82 and 1.14, respectively. The value of L shown below was 0.04. In the formula, the inequality sign is satisfied. L = [((450/550) -R (450) / R (550)) ² + ((650/5
50) -R (650) / R (550)) ² ) ^1/2 = 0.04 <0.1

The combination of the polymers is negative + negative + positive as follows. Monomer [A] Optical anisotropy: positive monomer [B] Optical anisotropy: negative Monomer component [C] + [D] Optical anisotropy: negative As a result, the retardation value is R (550) = 18.5 nm. Even when the value of is low, there is no change in the phase difference chromatic dispersion value,
It was confirmed that a retardation film having a wide band property of λ / n was obtained.

Therefore, when a synthetic polymer composed of three or more kinds of monomer components satisfying a specific condition is used, when a synthetic polymer composed of two kinds of monomer components having positive and negative optical anisotropy is used. It was confirmed that a retardation film having a broadband property of λ / 4 or λ / 2, which cannot be achieved, can be obtained.

As a weather resistance test of this retardation film, 10 ° C., 90% humidity and 90 ° C. humidity DRY were used.
Although it was held for 00 hours, no change in retardation or change in retardation wavelength dispersion characteristic was observed, and it could be confirmed that the film can be used as a retardation film having good weather resistance.

Reference Example 1 A polycarbonate polymerized with 100 (mol%) of the monomer component [A] was used. 18 wt% by dissolving this polycarbonate in methylene chloride
I made a dope. A cast film was prepared from this dope solution and stretched 1.8 times at a temperature of 165 degrees in a width-free uniaxial manner to obtain a retardation film.

This film is R (450) / R (55
The values of 0) and R (650) / R (550) were 1.08 and 0.96, respectively.

It was confirmed that this film had the largest in-plane refractive index in the stretching direction, and the refractive index anisotropy was positive. The shorter the measurement wavelength, the larger the phase difference.

Further, the film does not have the inequality sign in the following formula. L = [((450/550) -R (450) / R (550)) ² + ((650/550) -R (650) /
R (550)) ² ] ^1/2 = 0.34> 0.1

This result shows that in the homopolymer composed of the above-mentioned single monomers, the retardation wavelength dispersion has a wide band of λ.
It shows that the retardation film such as / 4 and λ / 2 cannot be satisfied.

Reference Example 2 A synthetic polymer obtained by polymerizing 100 (mol%) of the monomer component [B] was used. This synthetic polymer was dissolved in chloroform to prepare a 10 wt% dope. A cast film was prepared from this dope solution and stretched 1.8 times at a temperature of 245 ° C. in a width-free uniaxial manner to obtain a retardation film.

This film is R (450) / R (55
The values of 0) and R (650) / R (550) were 1.15 and 0.94, respectively.

It was confirmed that this film had the largest in-plane refractive index in the direction perpendicular to the stretching direction and the negative refractive index anisotropy. The shorter the measurement wavelength, the larger the phase difference.

In the formula below, the inequality sign was not applied. L = [((450/550) -R (450) / R (550)) ² + ((650/550) -R (650)
/ R (550)) ² ) ^1/2 = 0.41> 0.1

Similar to Reference Example 1, the result is that the homopolymer consisting of the above-mentioned single monomer cannot satisfy the retardation film such as λ / 4 and λ / 2 having the broadband retardation wavelength dispersion. Is shown.

[Reference Example 3] Styrene as a monomer component
-Isopropenylphenol copolymer [C] + [D] was used. 18 wt% by dissolving this copolymer in methylene chloride
% Dope was created. A cast film was prepared from this dope solution, and the width was freely set at a temperature of 110 degrees and 1.8 times.
Axial stretching was performed to obtain a retardation film.

This film is R (450) / R (55
The values of 0) and R (650) / R (550) were 1.07 and 0.96, respectively.

It was confirmed that this film had the largest in-plane refractive index in the direction perpendicular to the stretching direction and the negative refractive index anisotropy. The shorter the measurement wavelength, the larger the phase difference.

In the equation below, the inequality sign was not applied. L = [((450/550) -R (450) / R (550)) ² + ((650/550) -R (650) /
R (550)) ² ] ^1/2 = 0.34> 0.1

Similar to Reference Example 1, the result is that the homopolymer consisting of the above-mentioned single monomer cannot satisfy the retardation film such as λ / 4 and λ / 2 having the broadband retardation wavelength dispersion. Is shown.

[Reference Example 4] 3 parts of the monomer components [A] and [B] were used.
A polycarbonate copolymer copolymerized at a ratio of 3:67 (mol%) was used. This modified polycarbonate copolymer was dissolved in methylene chloride to prepare a 18 wt% dope. A cast film was prepared from this dope solution and stretched at a temperature of 230 ° C. in a widthwise uniaxial direction at 1.8 times to obtain a retardation film.

It was confirmed that the shorter the wavelength at the measuring wavelength, the smaller the retardation of this film, the largest in-plane refractive index in the stretching direction, and the positive refractive index anisotropy. In addition, R (450) / R (550) and R (6
50) / R (550) are 0.81 and 1.0, respectively.
It was 6.

This film did not have the inequality sign in the following formula as in the above Reference Example. L = [((450/550) -R (450) / R (550)) ² + ((650/550) -R (650) /
R (550)) ² ] ^1/2 = 0.12> 0.1

The results show that the two kinds of positive and negative polymers cannot be said to have extremely high broadband properties as retardation films of λ / 4, λ / 2, etc.

[Reference Example 5] Styrene as a monomer component
A polycarbonate-polystyrene copolymer obtained by copolymerizing -isopropenylphenol copolymer [C] + [D] and a monomer component [A] in a ratio of α: β = 40: 60 was used.
This polycarbonate-polystyrene copolymer was dissolved in methylene chloride to prepare an 18 wt% dope. A cast film was prepared from this dope solution and the temperature was adjusted to 13
Width-free uniaxial stretching was performed at 0 ° with a magnification of 1.8 to obtain a retardation film.

It was confirmed that this film had the largest in-plane refractive index in the stretching direction, and the refractive index anisotropy was positive. The shorter the measurement wavelength, the larger the phase difference. In addition, R (450) / R (550) and R (65
0) / R (550) values are 1.09 and 0.97, respectively.
Met.

This film did not have the inequality sign in the following formula. L = [((450/550) -R (450) / R (550)) ² + ((650/550) -R (650) /
R (550)) ² ] ^1/2 = 0.34> 0.1 This result shows that for these two types of positive and negative polymers, λ /
4 shows that the film having a λ / 2 retardation and the like does not have a sufficiently wide band.

[0144]

[Table 3]

[0145]

According to the present invention, a retardation film having a smaller retardation as the wavelength becomes shorter can be easily obtained.
It became possible to obtain a more ideal wide band property as a retardation film of λ / 2 or the like or λ / n (n> 0) with one retardation film. This retardation film can easily control the wavelength dispersion characteristic of the retardation by selecting the retardation wavelength dispersion value of three or more kinds of monomer components as the synthetic polymer that provides the material. A retardation film having such a retardation wavelength dispersion property and a retardation of λ / 4 can be combined with a polarizing film to provide a circularly polarizing film having excellent antireflection properties. Type liquid crystal display device, anti-transflective liquid crystal display device, transmissive liquid crystal display device, etc., can be contributed to the improvement of image quality.

[Brief description of drawings]

FIG. 1 is a polymer blend consisting of two components, polymer P and polymer Q, in which R (450) / R (550) with respect to volume fraction α.
Correlation diagram showing changes in the value of. (Polymer P and polymer Q both show positive optical anisotropy, and Rp (450) / Rp (550)> Rq (45
When there is a magnitude relationship of 0) / Rq (550). Where Rp (450), R
p (550), Rq (450) and Rq (550) are the in-plane retardation of the polymer oriented film at wavelengths 450 nm, 550 nm and 650 nm of polymer P and polymer Q, respectively. )

FIG. 2 is a polymer blend consisting of two components, polymer P and polymer Q, in which R (450) / R (550) with respect to volume fraction α.
Correlation diagram showing changes in the value of. (Polymer P and polymer Q both show positive optical anisotropy, and Rp (450) / Rp (550) <Rq (45
When there is a magnitude relationship of 0) / Rq (550). Where Rp (450), R
p (550), Rq (450) and Rq (550) are the in-plane retardation of the polymer oriented film at wavelengths 450 nm, 550 nm and 650 nm of polymer P and polymer Q, respectively. )

FIG. 3 is a polymer blend consisting of two components, polymer P and polymer Q, where R (450) / R (550) with respect to volume fraction α.
Correlation diagram showing changes in the value of. (Polymer P and polymer Q both show negative optical anisotropy, and Rp (450) / Rp (550)> Rq (4
50) / Rq (550). Where Rp (450),
Rp (550), Rq (450), and Rq (550) are in-plane retardation of the polymer oriented film at wavelengths 450 nm, 550 nm, and 650 nm of polymer P and polymer Q, respectively. )

4 is a polymer blend consisting of two components, polymer P and polymer Q, in which R (450) / R (550) with respect to volume fraction α.
Correlation diagram showing changes in the value of. (Polymer P and polymer Q both show negative optical anisotropy, and Rp (450) / Rp (550) <Rq (45
When there is a magnitude relationship of 0) / Rq (550). Where Rp (450), R
p (550), Rq (450) and Rq (550) are the in-plane retardation of the polymer oriented film at wavelengths 450 nm, 550 nm and 650 nm of polymer P and polymer Q, respectively. )

5 is a polymer blend consisting of two components, polymer P and polymer Q, R (450) / R (550) with respect to volume fraction α.
Correlation diagram showing changes in the value of. (Polymer P exhibits positive optical anisotropy, polymer Q exhibits negative optical anisotropy, and Rp (45
When the relationship is 0) / Rp (550)> Rq (450) / Rq (550).
Here, Rp (450), Rp (550), Rq (450), and Rq (550) are wavelengths 450 nm, 550 nm, and 650 nm of the polymers P and Q, respectively.
2 is an in-plane retardation of the polymer oriented film in FIG. )

6 is a polymer blend consisting of two components, polymer P and polymer Q, in which R (450) / R (550) with respect to volume fraction α.
Correlation diagram showing changes in the value of. (Polymer P exhibits positive optical anisotropy, polymer Q exhibits negative optical anisotropy, and Rp (45
When the relation of 0) / Rp (550) <Rq (450) / Rq (550) is satisfied.
Here, Rp (450), Rp (550), Rq (450), and Rq (550) are wavelengths 450 nm, 550 nm, and 650 nm of the polymers P and Q, respectively.
2 is an in-plane retardation of the polymer oriented film in FIG. )

7 is a polymer blend consisting of two components, polymer P and polymer Q, in which R (450) / R (550) with respect to volume fraction α.
Correlation diagram showing changes in the value of. (Polymer P exhibits negative optical anisotropy, polymer Q exhibits positive optical anisotropy, and Rp (45
When the relationship is 0) / Rp (550)> Rq (450) / Rq (550).
Here, Rp (450), Rp (550), Rq (450), and Rq (550) are wavelengths 450 nm, 550 nm, and 650 nm of the polymers P and Q, respectively.
2 is an in-plane retardation of the polymer oriented film in FIG. )

8 is a polymer blend consisting of two components, polymer P and polymer Q, R (450) / R (550) with respect to volume fraction α.
Correlation diagram showing changes in the value of. (Polymer P exhibits negative optical anisotropy, polymer Q exhibits positive optical anisotropy, and Rp (45
When the relation of 0) / Rp (550) <Rq (450) / Rq (550) is satisfied.
Here, Rp (450), Rp (550), Rq (450), and Rq (550) are wavelengths 450 nm, 550 nm, and 650 nm of the polymers P and Q, respectively.
2 is an in-plane retardation of the polymer oriented film in FIG. )

FIG. 9 shows the values of R (450) / R (550) and R (650) / R (55) in a polymer blend consisting of two components, polymer P and polymer Q.
The correlation diagram showing the change of the value of (0). (When both polymer P and polymer Q exhibit positive or negative optical anisotropy.)

FIG. 10 shows the values of R (450) / R (550) and R (650) / R in a polymer blend consisting of two components, polymer P and polymer Q.
Correlation diagram showing changes in the value of (550). (When the polymer P exhibits positive optical anisotropy and the polymer Q exhibits negative optical anisotropy.)

FIG. 11 shows the values of R (450) / R (550) and R (650) / R in a polymer blend consisting of polymer P and polymer Q.
Correlation diagram showing changes in the value of (550). (When the polymer P exhibits negative optical anisotropy and the polymer Q exhibits positive optical anisotropy.)

FIG. 12: R (450) / R (550) required for polymer X to obtain ideal point I in a polymer blend consisting of polymer P, polymer Q and polymer X Value and R (65
The model figure showing the area | region of the value of 0) / R (550). (When both polymer P and polymer Q exhibit positive or negative optical anisotropy.)

FIG. 13: R (450) / R (550) required for polymer X to obtain ideal point I in a polymer blend consisting of polymer P, polymer Q and polymer X Value and R (65
The figure showing the area | region of the value of 0) / R (550). (Polymer P, Polymer Q
Both show positive optical anisotropy, and the polymer X shows negative optical anisotropy. )

FIG. 14: R (450) / R (550) required for polymer X to obtain ideal point I in a polymer blend consisting of polymer P, polymer Q and polymer X Value and R (65
The figure showing the area | region of the value of 0) / R (550). (Polymer P, Polymer Q
Both show negative optical anisotropy, and the polymer X shows positive optical anisotropy. )

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H049 BA03 BA06 BA25 BB44 BB46                       BB47 BB49 BB51 BB62 BC03                       BC09 BC14 BC22                 4F071 AA12 AA22 AA26 AA33 AA34                       AA50 AA60 AF30 AF35 BB02                       BB03 BB04 BB06 BB07 BC01                       BC02                 4J029 AA09 AB07 AC02 BB13A                       HC01 HC05 KE09                 5D119 AA05 EC47 FA08 JA32 NA05                 5D789 AA05 EC47 FA08 JA32 NA05

Claims (8)

[Claims] 1. A method for producing a retardation film which satisfies λ / n (n> 0) in a wide wavelength region in a single layer, and is selected so as to satisfy the following conditions (i) and (ii). A method for producing a retardation film, which comprises orienting a synthetic polymer film comprising at least three kinds of monomer components. (I) Two of the above-mentioned monomer components are polymers P _ab substantially composed of the monomer components.
And Q _cd both show positive refractive index anisotropy, and the polymer X _ef composed of other monomer components has negative refractive index anisotropy. (Ii) When the phase difference wavelength dispersion values of P _ab and Q _cd are (a, b) and (c, d), respectively, the phase difference wavelength dispersion value (e, f) of the polymer X _ef is expressed by the following formula ( 1) or (2)
Meet (650 / 550-b) / (450 / 550-a)> (650 / 550-f) / (450 / 550-e)> (650 / 550-d) / (450 / 550-c) (1) (650 / 550-b) / (450 / 550-a) <(650 / 550-f) / (450 / 550-e) <(650 / 550-d) / (450 / 550-c) (2) (Here, the phase difference wavelength dispersion values (a, b) (c, d) and (e, f) have wavelengths of 450 nm, 550 nm and 650 n.
The in-plane retardation of the retardation film at m is R (45
0), R (550), R (650)
(450) / R (550), R (650) / R (55
0)) is shown. ) 2. A method for producing a retardation film which satisfies λ / n (n> 0) in a wide wavelength region in a single layer, and is selected so as to satisfy the following conditions (iii) and (iv). A method for producing a retardation film, which comprises orienting a synthetic polymer film comprising at least three kinds of monomer components. (Iii) Two of the above-mentioned monomer components are polymers P ′ _ab and Q ′ _cd , which are substantially composed of the monomer components, respectively, and both have negative refractive index anisotropy
The refractive index anisotropy of the polymer _X'ef composed of other monomer components is positive. (Iv) The phase difference chromatic dispersion values of P ′ _ab and Q ′ _cd are (a ′, b ′), (c ′,
d ′), the retardation wavelength dispersion value (e ′, f ′) of the polymer X ′ _ef satisfies the following formula (3) or (4). (650 / 550-b ') / (450 / 550-a')> (650 / 550-f ') / (450 / 550-e')> (650 / 550-d ') / (450/55 0 -c ') (3) (650 / 550-b') / (450 / 550-a ') <(650 / 550-f') / (450 / 550-e ') <(650 / 550-d' ) / (450 / 550-c ') (4) (where, the phase difference wavelength dispersion value (a', b ') (c',
d ') and (e', f ') have wavelengths of 450 nm and 550
(R (450) / R (550), R (650) / R, where R (450), R (550), and R (650) are in-plane retardations of the retardation film at nm and 650 nm, respectively.
(550)) is shown. ) 3. The method for producing a retardation film according to claim 1, wherein one of the at least three kinds of monomer components has a fluorene ring. 4. The synthetic polymer is polycarbonate.
The manufacturing method of the retardation film in any one of Claims 1-3. 5. A retardation film obtained by orienting a synthetic polymer film comprising at least three kinds of monomer components. The retardation film is a single layer and has a wavelength of 450 nm and 55
A retardation film having retardations at 0 nm and 650 nm satisfying the following formulas (5) and (6). R (450) <R (550) <R (650) (5) L = [((450/550) -R (450) / R (550)) ² + ((650/550) -R (650) / R (550)) ² ] ^1/2 <0.1 (6) (where R (450), R (550), R (650)
Are wavelengths of 450 nm, 550 nm, and 650 nm, respectively.
Is the in-plane retardation of the retardation film in 6. The retardation film according to claim 5, wherein one of the at least three kinds of monomer components has a fluorene ring. 7. The retardation film according to claim 5, wherein the synthetic polymer is polycarbonate. 8. A circularly polarizing film comprising the polarizing film and the retardation film according to claim 5.