JP2001235622A - Phase difference plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phase difference plate with high-performance in a wide band, which can be formed at a low cost from single material without needing laminating formation. SOLUTION: The phase difference plate is formed by using a composition containing a copolymer satisfying Δn (450)<Δn (550)<Δn (650), when the specific double refractivity value (Δn) in wavelength of 450 nm, wavelength of 550 nm and wavelength of 650 nm is defined as the Δn (450), the Δn (550) and the >=n(650), respectively, and has a chain showing the positive uniaxiality and a chain showing the negative uniaxiality, when a uniaxial orientation rule is given. It is preferable that the chain showing the positive uniaxiality is a norbornene chain, and the chain showing the negative uniaxiality is at least one kind selected from a styrene chain, a styrene/maleic anhydride copolymer chain, a styrene/acrylonitrile copolymer chain, a styrene/methyl metacrylate copolymer chain or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type liquid crystal display device which can be used as a display device in various fields such as a personal computer, an AV device, a portable information communication device, a game and a simulation device, and a vehicle navigation system. And a phase difference plate suitable for

[0002]

2. Description of the Related Art A λ / 4 plate whose retardation (Re) is ４ of the wavelength is used for many applications such as a reflection type LCD, an optical disk pickup, and an antiglare film. On the other hand, a λ / 2 plate whose retardation (Re) is １ ／ of the wavelength is used for a liquid crystal projector or the like. As the λ / 4 plate and the λ / 2 plate,
In each application, it is desired that the function is sufficiently exhibited for all incident light in a visible light region visible to human eyes. Examples of a wide-band retardation plate that functions as a λ / 4 plate or a λ / 2 plate for incident light in the entire visible light region include, for example, JP-A-5-27118 and JP-A-5-1001.
No. 14, JP-A-10-68816, JP-A-1
Japanese Patent Application Laid-Open No. 0-90521 and the like propose a laminate formed by laminating two polymer films having mutually different optical anisotropy.

However, in these cases, two types of chips obtained by cutting a stretched film stretched in one direction at directions different from each other with respect to the stretching direction are obtained, and these are laminated. Need to be laminated. In this λ / 4 plate, the optical anisotropy (tilt of the optical axis and slow axis) of each polymer film is determined by the angle at which the chip is cut with respect to the stretching direction of the stretching film. , Precise cutting technology is required. When bonding two chips, apply an adhesive,
Precise positioning is required, and the manufacturing process is complicated. In other words, it is necessary to carry out processes such as adhesive processing, chipping, bonding, and other cost-increase factors, which have an adverse effect on actual performance such as contamination of processing chips due to chipping, and variations in phase difference due to errors in bonding angles. Have a problem. Broadband λ / 4 having retardation of 波長 wavelength or 波長 wavelength in the entire visible light range and having durability to withstand use
At present, a technique for forming a plate and a broadband λ / 2 plate with a single material instead of laminating has not been provided yet.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to solve the following problems. SUMMARY OF THE INVENTION An object of the present invention is to provide a high-performance phase difference plate that can be formed at a low cost with a single material without the need for lamination.

[0005]

Means for solving the above problems are as follows. That is, <1> when a uniaxial orientation rule is given, a chain having a positive uniaxial property and a chain having a negative uniaxial property are provided.
The intrinsic birefringence values (Δn) at 50 nm, 550 nm, and 650 nm are represented by Δn (450) and Δn (55, respectively).
0) and Δn (650), Δn (450) <Δ
A retardation plate formed using a composition containing a copolymer that satisfies n (550) <Δn (650). <2> The retardation plate according to <1>, wherein the chain exhibiting positive uniaxiality is a norbornene chain. <3> The chain exhibiting negative uniaxiality is at least one selected from a styrene chain, a styrene / maleic anhydride copolymer chain, a styrene / acrylonitrile copolymer chain, and a styrene / methyl methacrylate copolymer chain. Some said <
It is a phase difference plate as described in <1> or <2>. <4> The copolymer is a graft copolymer having a main chain and a graft chain graft-bonded to the main chain, wherein the main chain is a norbornene chain, and the graft chain is a styrene compound chain. The retardation plate according to any one of <1> to <3>. <5> The value of (retardation (Re) / wavelength) at wavelengths of 450 nm, 550 nm, and 650 nm is 0.2.
<1> which is a broadband quarter-wave plate.
To <4>. <6> The value of (retardation (Re) / wavelength) at wavelengths of 450 nm, 550 nm, and 650 nm is 0.4.
5 to 0.55, which is a broadband half-wave plate.
A retardation plate according to any one of <1> to <4>.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The retardation plate of the present invention, when given a uniaxial orientation rule, has a positive uniaxial chain and a negative uniaxial chain, and has a wavelength of 450 nm. , Wavelength 55
The intrinsic birefringence values (Δn) at 0 nm and 650 nm are represented by Δn (450), Δn (550), and Δn (65, respectively).
0), Δn (450) <Δn (550) <Δ
It is formed using a composition containing a copolymer satisfying n (650). Here, the intrinsic birefringence indicates a birefringence that appears when the material is given complete uniaxiality. In a normal orientation, complete uniaxiality is rarely seen, and the following relationship exists between the birefringence and the intrinsic birefringence in an imperfect orientation. (Birefringence) = (degree of orientation) × (intrinsic birefringence) where (degree of orientation) = <(3 cos ² θ−1) / 2>
Is the angle between the stretching direction (average orientation direction) and the orientation direction of an arbitrary chain, and the above formula means the average value of the case of each chain. Since the degree of orientation is determined by the arrangement of molecules, it does not depend on the wavelength. Therefore, Δn (450) <Δn (550) <Δn (65) on the basis of intrinsic birefringence.
The expression 0) means that the birefringence in a general case where the orientation is incomplete is satisfied. The composition contains the copolymer, and may further contain, if necessary, other components appropriately selected within a range that does not impair the effects of the present invention.

[0007] The copolymer has a positive uniaxial chain and a negative uniaxial chain when given a uniaxial orientation rule. In the present invention, the copolymer is preferably a graft copolymer having a main chain and a graft chain graft-bonded to the main chain, and the main chain is a positive uniaxial chain. In particular, it is particularly preferable that the graft chain is a graft copolymer having the negative uniaxiality.

As the positive uniaxial chain, a norbornene chain is preferable, and specifically, the following structural formulas (I) to (I):
A chain containing a norbornane skeleton represented by any of (IV) is preferred.

[0009]

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[0010]

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[0011]

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[0012]

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In the above structural formula, A, B, D and E are
Represents a hydrogen atom, a halogen atom, or a hydrocarbon group. The hydrocarbon group has 1 to 12 carbon atoms and may be substituted with a substituent. Specific examples thereof include-(CH ₂ ) _n C
OOR ¹ , — (CH ₂ ) _n OCOR ¹ , — (CH ₂ ) _n O
_{^{R 1, - (CH 2)}} n CN, - (CH 2) n CONR 2 R 3,
— (CH ₂ ) _n X. B and D may combine with each other to form a ring, and in this case, the ring includes a cyclic alkylene group, -OC-O-CO-, -OC-NR ⁴
—CO—, and the like. R ¹ , R ² , R ³ and R
⁴ represents a hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a substituent. X represents SiR ⁵ _p Z _3p. R
⁵ represents a hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group may be substituted with a halogen atom. Z represents a halogen atom, —OCOR ⁶ or OR ⁶ . R ⁶ represents a hydrocarbon group having 1 to 10 carbon atoms. p represents an integer of 0 to 3. n represents an integer of 0 to 10.

The proportion of the positive uniaxial chains in the copolymer differs depending on the type of the monomers contained in the copolymer and cannot be specified unconditionally.
0 to 90% is preferable, and 30 to 80% is more preferable.

The chain exhibiting the negative uniaxiality is preferably a styrene compound chain, and specifically, a styrene chain, a styrene / maleic anhydride copolymer chain, a styrene / acrylonitrile copolymer chain, and a styrene / chain. At least one selected from methyl methacrylate copolymer chains is preferred.

The copolymer is preferably obtained by graft-polymerizing the positive uniaxial chain with the negative uniaxial chain. The copolymer has a structure in which the positive uniaxial chain is a main chain, and the negative uniaxial chain is grafted to the main chain as a graft chain.

As the monomer constituting the positive uniaxial chain, a norbornene-based compound is preferably exemplified.
Examples of the positive uniaxial chain include a cyclic olefin-based resin having a norbornene skeleton. Examples of the cyclic olefin resin include, for example, JP-A-60-16
Nos. 8708 and 62-133413 and 63
JP-A-264626, JP-A-1-240517, JP-A-5-93079, JP-A-5-112474, JP-A-7-62028, JP-A-7-196736, JP-A-7-196779, Japanese Patent Publication No. 57-8815
And those described in Japanese Unexamined Patent Application Publication No. H10-174, etc. are preferred.

As the monomer constituting the negative uniaxial chain, styrene compounds are preferred. Examples of the styrene compound include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-nitrostyrene, p-aminostyrene, p-carboxystyrene, p-phenylstyrene, and 2,5- Dichlorostyrene, pt-butylstyrene, and the like are preferred.

The monomer constituting the negative uniaxial chain may contain other compounds in addition to the styrene compound. Examples of the compound include acrylonitrile and methacrylonitrile. , Α-chloroacrylonitrile, methyl methacrylate, ethyl methacrylate, methyl acrylate, ethyl acrylate, acrylic acid, butadiene, isoprene, maleic anhydride, vinyl acetate, ethylene, propylene and the like. These may be used alone or in combination of two or more.

The method of the graft polymerization is not particularly limited, and includes bulk polymerization, precipitation polymerization, emulsion polymerization, solution polymerization,
A known polymerization method such as suspension polymerization is preferably used.
Among these, suspension polymerization or solution polymerization is preferred.

As the method of the suspension polymerization, for example, referring to the method described in “Experimental Method for Polymer Synthesis” (Takashi Otsu and Masayoshi Kinoshita, Kagaku Dojinsha), p.130 and p.146-147. can do.

According to the suspension polymerization, the copolymer is
Particles of 50 μm or more are obtained by an addition polymerization reaction initiated by an oil-soluble initiator using an aqueous dispersion medium in the presence of an inorganic salt and / or a water-soluble polymer dispersant.

The above-mentioned inorganic salts are used for the purpose of stabilizing the dispersion, preventing the water-solubility of the monomer (monomer), etc., and include, for example, sodium chloride, potassium chloride, calcium chloride, magnesium chloride, ammonium chloride, potassium sulfate, sulfuric acid. Calcium, magnesium sulfate, ammonium sulfate, potassium aluminum sulfate, sodium carbonate, potassium carbonate, calcium hydrogen phosphate, and the like.

Examples of the water-soluble polymer dispersant include polyvinyl alcohol, sodium polyacrylate, an alkali hydrolyzate of a styrene-maleic anhydride copolymer (eg, “Isoban” manufactured by Kuraray Co., Ltd.), sodium alginate and Functional cellulose derivatives ("Mayprogat", "Kelco SCS", "Coar Gum", manufactured by Sanseki Co., Ltd., "MH-K", manufactured by Hoechst Japan K.K.).

In the present invention, calcium hydrogen phosphate, polyvinyl alcohol, sodium polyacrylate, an alkali hydrolyzate of a styrene / maleic anhydride copolymer or the like may be used alone or in combination with sodium chloride, chloride, or the like. It is preferable to use potassium, calcium chloride, magnesium sulfate and the like in combination.

As the polymerization initiator used in the suspension polymerization, a water-insoluble and oil-soluble polymerization initiator is preferable. For example, azobis (cyclohexane-1-carbonitrile), azobisisobutyronitrile, 2,2 '-Azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile), dimethyl 2,2'-azobisisobutyrate, benzoyl peroxide, lauroyl peroxide, T-butyl peroxide,
T-amyl peroxide, cumyl peroxide, t-butyl peroxide benzoate, t-butyl peroxide phenylacetate,
And the like. Among these, peroxide-based polymerization initiators are preferred.

The polymerization temperature at the time of the graft polymerization differs depending on the type of the monomer to be subjected to the graft polymerization, the boiling point, the ceiling temperature (the temperature at which the polymerization and the depolymerization reach an equilibrium), and the like, and are generally defined. Can not, but usually
It is 0-100 degreeC, and 40-90 degreeC is preferable.

In the case of the suspension polymerization, first, the monomer constituting the negative uniaxial chain or the monomer constituting the negative uniaxial chain is combined with the positive uniaxial chain. A mixture with the indicated chain (polymer) is dissolved in a solvent to prepare a solution. Examples of the solvent include halogenated organic solvents such as chloroform and carbon tetrachloride, aromatic hydrocarbon solvents such as benzene and toluene, ethyl acetate, acetone, and the like. Next, the positive uniaxial chain (polymer) is dissolved in the solution to prepare a mixed solution. Then, the inorganic salt and / or the water-soluble polymer dispersant are mixed and dispersed in the mixed solution, and further, in the presence of the polymerization initiator,
It can be performed under good stirring conditions.

In the case of the solution polymerization, first, the chain (polymer) having the positive uniaxiality is dissolved in a solvent to prepare a solution. Examples of the solvent include halogenated organic solvents such as chloroform and carbon tetrachloride, aromatic hydrocarbon solvents such as benzene and toluene, ethyl acetate, acetone, and the like. To this, a monomer constituting the negative uniaxial chain is mixed to prepare a mixed solution. Then, the polymerization initiator is added to the mixed solution, and the mixture can be performed under good stirring conditions. The temperature of the solution polymerization varies depending on the type of the solvent used and cannot be specified unconditionally, but is preferably 40 ° C. or higher.

In the suspension polymerization or the solution polymerization, the monomer constituting the difference exhibiting the negative uniaxiality is mixed in advance with the chain (polymer) exhibiting the positive uniaxiality in a total amount. May be included, a part of them may be mixed,
They may be separated without mixing. Alternatively, the entirety of the positive uniaxial chain (polymer) may be charged into a reaction vessel, and the monomer constituting the negative uniaxial chain may be dropped therein. The polymerization initiator may be added in its entirety to the reaction vessel in advance, may be added in portions, or may be dissolved in a solution and then dropped into the reaction vessel.

Hereinafter, a synthesis example of the copolymer will be described. The method for synthesizing the copolymer is not limited to the synthesis example.

(Synthesis Example 1) According to Reference Example 1 described in JP-A-7-62028, 8-methyl-8-carboxyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-
Solution polymerization in a toluene solution using dodecene and 1-hexene was performed by changing the ratio of 1-hexene to dodecene monomer, and three kinds of polymers having different molecular weights, polynorbornene (I) ( Mw = 133,000), polynorbornene (II) (Mw = 95,000), and polynorbornene (III) (Mw = 46,000). In addition, these three types of polymers are chains (polymers) exhibiting the positive uniaxiality.

Next, 1.5 g of sodium polyacrylate (number average degree of polymerization: 15,000) and 2 g of sodium bisulfite were placed in a two-liter three-necked flask equipped with a stirrer and a reflux condenser, and 800 ml of distilled water was added. Dissolved.
On the other hand, 140 g of the polynorbornene (I) and styrene 48 as a monomer constituting the negative uniaxial chain are used.
g and acrylonitrile 12 g were dissolved in 1,2-dichloroethane 200 ml to prepare a mixed solution. 10% by volume of the prepared mixed solution was further added to the two-liter three-necked flask, and the mixture was heated at 65 ° C. under a nitrogen stream.
And stirred vigorously.

Further, a solution prepared by dissolving 0.9 g of benzoyl peroxide in 30 ml of isopropyl alcohol as a polymerization initiator was added thereto, followed by heating and stirring for 1 hour, and then the remaining mixed solution was dropped at a constant speed over 2 hours. . After dropping,
After one hour, 10 ml of isopropyl alcohol in which 0.9 g of benzoyl peroxide was dissolved was added. Thereafter, the internal temperature was raised to 75 ° C., and heating was continued for 4 hours, and then the organic solvent was distilled off under reduced pressure. After cooling, the obtained dispersion was separated by centrifugal filtration, washed sufficiently with water and methanol, and dried. From the above, 195 g of the above-mentioned graft copolymer P-1 was obtained. The average molecular weight of the obtained graft copolymer P-1 was 180,000.

Similarly, the following graft copolymer P-2
~ 15 were synthesized. In the following, "(A)"
Represents a positive uniaxial chain (main chain);
“(B)” is a chain showing the negative uniaxiality (graft chain).
Represents The obtained graft copolymers P-2 to P-15 have a structure in which the graft chain (B) is graft-bonded to the main chain (A). The values in parentheses indicate the copolymerization ratio (mass) of each monomer, and the values of “(A) / (B)” indicate the mass percentage ratio.

(Graft copolymer P-2) (A) Polynorbornene (I) (B) Styrene / acrylonitrile (75/25) (A): (B) = 70/30 (Graft copolymer P-3) (A) Polynorbornene (I) (B) Styrene / acrylonitrile / α-methylstyrene (60/20/20) (A): (B) = 70/30

(Graft copolymer P-4) (A) Polynorbornene (I) (B) Styrene (A): (B) = 75/25 (Graft copolymer P-5) (A) Polynorbornene ( II) (B) Styrene / acrylonitrile (75/25) (A): (B) = 70/30

(Graft copolymer P-6) (A) Polynorbornene (II) (B) Styrene / acrylonitrile (75/25) (A): (B) = 50/50 (Graft copolymer P-7) (A) Polynorbornene (II) (B) Styrene / acrylonitrile (75/25) (A): (B) = 30/70 (graft copolymer P-8) (A) Polynorbornene (II) (B ) Styrene / acrylonitrile (75/25) (A): (B) = 20/80

(Graft copolymer P-9) (A) Polynorbornene (II) (B) Styrene / maleic anhydride (50/50) (A): (B) = 50/50 (Graft copolymer P -10) (A) Polynorbornene (II) (B) Styrene / p-methylstyrene (75/25) (A): (B) = 80/20

(Graft copolymer P-11) (A) Polynorbornene (III) (B) Styrene / acrylonitrile (75/25) (A): (B) = 70/30 (Graft copolymer P-12) (A) Polynorbornene (III) (B) Styrene / methyl methacrylate (60/40) (A): (B) = 65/35

(Graft copolymer P-13) (A) Polynorbornene (III) (B) Styrene / methacrylonitrile (75/25) (A): (B) = 70/30 (Graft copolymer P -14) (A) polynorbornene (III) (B) styrene / t-butyl methacrylate (80/2
0) (A): (B) = 70/30 (Graft copolymer P-15) (A) Polynorbornene (III) (B) Styrene / acrylonitrile / α-methylstyrene (70/15 · 15) (A ): (B) = 75/25

The retardation plate of the present invention may be formed using a composition containing the copolymer alone, or using a composition containing two or more copolymers. Alternatively, the copolymer, a norbornene chain (a polymer containing a norbornene-based compound as a monomer) as the main chain, and a styrene-based compound chain (a styrene-based compound) as the graft chain may be formed. (A polymer containing as a monomer).

The content of the copolymer in the composition is preferably from 1 to 100% by mass, more preferably from 5 to 100% by mass.

The molecular weight of the copolymer is not particularly limited and may be appropriately selected depending on the intended purpose. However, when the composition is made into a solution to form a retardation plate, the weight average molecular weight may be reduced. It is preferably from 5,000 to 1,000,000, and more preferably from 10,000 to 500,000.

The copolymer has a wavelength of 450 nm and 550 nm.
The values of the retardation (Re) at nm and 650 nm are Re (450), Re (550), and Re, respectively.
(650), these are represented by the following formula: Re (450)
It is necessary to satisfy <Re (550) <Re (650).

The method for producing the retardation plate of the present invention is not particularly limited, and can be appropriately selected according to the purpose. For example, it can be manufactured as follows.
That is, a retardation plate according to a solution film forming method in which a composition containing the copolymer is formed into a solution by applying a solution, followed by drying, or an extrusion forming method in which a composition is pelletized and melt-extruded to form a film, or the like. Can be manufactured.

The retardation film obtained above has a wavelength of 45
The values of the retardation (Re) at 0 nm, 550 nm, and 650 nm are represented by Re (450) and Re, respectively.
(550) and Re (650), these are represented by the following formula: Re (450) <Re (550) <Re (65)
0)) can be used as it is, but when the above formula is not satisfied, by changing conditions such as the composition ratio and the stretching temperature, the retardation ( Re) can be controlled.

The stretching preferably includes longitudinal uniaxial stretching in the mechanical flow direction and transverse uniaxial stretching (eg, tenter stretching) in the direction perpendicular to the mechanical flow direction. Biaxial stretching may be performed as long as the film has anisotropy.

The retardation plate of the present invention has a wavelength of 450 nm,
(Retardation (R) at 50 nm and 650 nm
e) / wavelength) having a value of 0.2 to 0.3 can be used as a broadband quarter-wave plate,
A value of 0.55 can be used as a broadband half-wave plate.

-Applications- Since the retardation plate of the present invention exhibits desired characteristics in a single molded body, it is not necessary to laminate two or more sheets, it can be manufactured at low cost, and a wide band λ / 4 It can be used as a board, a broadband λ / 2 board, etc. and exhibits high performance in a wide band, so it can be used in various fields such as personal computers, AV equipment, portable information communication equipment, games and simulation equipment, and in-car navigation systems. It can be suitably used for a reflection type liquid crystal display device and the like which can be used as a display device of the invention.

[0051]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Example 1) As the copolymer, the graft copolymer P-1 was dissolved in a methylene chloride solution to prepare a coating solution (25% by weight). The coating solution was cast on a glass plate using a doctor blade, dried,
A transparent film having a thickness of 104 μm was formed. This transparent film was uniaxially stretched at 150 ° C. for 23% to obtain a retardation plate. The wavelength dispersion of the Re value of the retardation plate was measured using a retardation measuring device (KOBRA21DH, manufactured by Oji Scientific Instruments). The result is shown in FIG. As shown in FIG. 1, the retardation plate has a wavelength of 450 n.
m, 550 nm, and 650 nm, the values of the retardation (Re) were Re (450) and Re (55), respectively.
0) and Re (650), these are represented by the following formula:
(450) <Re (550) <Re (650), and exhibited a quarter-wave plate characteristic over a wide band.

Comparative Example 1 In Example 1, the copolymer was changed to the polynorbornene (I), the thickness of the transparent film was 105 μm, and the transparent film was 155 ° C.
, A retardation plate was produced in the same manner as in Example 1, except that the wavelength dispersion of the Re value was measured in the same manner as in Example 1. The result is shown in FIG. As shown in FIG. 1, the retardation plate did not exhibit broadband quarter-wave plate characteristics.

Comparative Example 2 The procedure of Example 1 was repeated except that the copolymer was changed to styrene / acrylonitrile (80/20), the thickness of the transparent film was 97 μm, and the transparent film was uniaxially stretched at 110 ° C. by 17%. A phase difference plate was manufactured in the same manner as in Example 1, and the wavelength dispersion of the Re value was measured in the same manner as in Example 1. The result is shown in FIG. FIG.
As shown in the figure, the retardation plate did not show the characteristics of a wide-band quarter-wave plate.

Example 2 As the copolymer, a coating solution (25% by weight) was prepared by dissolving the graft copolymer P-1 in a methylene chloride solution. The coating solution was cast on a glass plate using a doctor blade, dried,
A transparent film having a thickness of 210 μm was formed. This transparent film was uniaxially stretched at 150 ° C. for 23% to obtain a retardation plate. The wavelength dispersion of the Re value of the retardation plate was measured using a retardation measuring device (KOBRA21DH, manufactured by Oji Scientific Instruments). The result is shown in FIG. As shown in FIG. 2, the retardation plate has a wavelength of 450 n.
m, 550 nm, and 650 nm, the values of the retardation (Re) were Re (450) and Re (55), respectively.
0) and Re (650), these are represented by the following formula:
(450) <Re (550) <Re (650), and the half-wave plate characteristic was exhibited in a wide band.

Comparative Example 3 In Example 2, the copolymer was changed to polynorbornene (I), the thickness of the transparent film was set to 219 μm, and the transparent film was heated at 155 ° C. for 3 hours.
A retardation plate was prepared in the same manner as in Example 1 except that the film was uniaxially stretched by 5%, and the wavelength dispersion of the Re value was measured in the same manner as in Example 2. The result is shown in FIG. As shown in FIG. 2, the retardation plate did not exhibit broadband half-wave plate characteristics.

Comparative Example 4 In Example 2, except that the copolymer was changed to styrene / acrylonitrile (75/25), the thickness of the transparent film was changed to 127 μm, and the transparent film was uniaxially stretched at 110 ° C. by 24%. Example 1
In the same manner as in Example 2, a retardation plate was produced.
The chromatic dispersion of the value was measured. The result is shown in FIG. As shown in FIG. 2, the retardation plate did not exhibit broadband half-wave plate characteristics.

[0058]

According to the present invention, it is possible to solve the above-mentioned conventional problems, and it is possible to form a phase difference plate that can be formed at a low cost with a single material without the necessity of lamination, and has a high performance in a wide band. Can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing the measurement results of the wavelength dispersion characteristics of the Re value in the visible light region of the retardation films manufactured in Example 1 and Comparative Examples 1 and 2.

FIG. 2 is a diagram showing the measurement results of the wavelength dispersion characteristics of the Re value in the visible light region of the retardation films manufactured in Example 2 and Comparative Examples 3 and 4.

Continued on the front page F term (reference) 2H049 BA06 BA07 BB46 BB47 BB48 BB50 BC22 2H091 FA11X FA11Z FB02 FC08 LA12 LA16 4F071 AA21 AA21X AA22X AA33X AA34X AA36X AA77 AF29 AF31Y AH12 AH19 BB01 BB06

Claims (6)

[Claims] When a uniaxial orientation rule is given, a chain having a positive uniaxiality and a chain having a negative uniaxiality are provided,
The intrinsic birefringence values (Δn) at wavelengths of 450 nm, 550 nm, and 650 nm are represented by Δn (450) and Δn, respectively.
(550) and Δn (650), Δn (45)
0) A retardation plate formed using a composition containing a copolymer satisfying <Δn (550) <Δn (650). 2. The retardation plate according to claim 1, wherein the positive uniaxial chain is a norbornene chain. 3. A chain exhibiting negative uniaxiality is at least one selected from a styrene chain, a styrene / maleic anhydride copolymer chain, a styrene / acrylonitrile copolymer chain, and a styrene / methyl methacrylate copolymer chain. The retardation plate according to claim 1 or 2, which is a seed. 4. The copolymer is a graft copolymer having a main chain and a graft chain graft-bonded to the main chain, wherein the main chain is a norbornene chain, and the graft chain is a styrene compound chain. The retardation plate according to any one of claims 1 to 3, wherein 5. Wavelength 450 nm, 550 nm, 650 n
The retardation plate according to any one of claims 1 to 4, wherein the value of (retardation (Re) / wavelength) at m is 0.2 to 0.3, and the plate is a broadband quarter-wave plate. 6. Wavelength 450 nm, 550 nm, 650 n
The retardation plate according to any one of claims 1 to 4, wherein a value of (retardation (Re) / wavelength) at m is 0.45 to 0.55, and the plate is a broadband half-wave plate.