JP5982828B2 - Laminated film for optical compensation - Google Patents

Description

  The present invention relates to a laminated film for optical compensation, and more specifically, a film using a fumarate ester resin having a high out-of-plane retardation even in a thin film and a uniaxially stretched film are laminated, and the NZ coefficient is The present invention relates to a laminated film for optical compensation of 0.3 to 0.7.

  A liquid crystal display is widely used as a most important display device in a multimedia society, such as a mobile phone, a computer monitor, a notebook computer, and a television. Many optical films are used in liquid crystal displays to improve display characteristics. In particular, retardation films play a large role in improving contrast and compensating for color tone when viewed from the front or obliquely. As the conventional retardation film, polycarbonate or cyclic polyolefin is used, and these polymers are polymers having positive birefringence. Here, the sign of birefringence is defined as shown below.

  The optical anisotropy of the polymer film molecularly oriented by stretching or the like can be represented by a refractive index ellipsoid shown in FIG. Here, the refractive index in the fast axis direction in the film plane when the film is stretched is represented by nx, the refractive index in the film in-plane direction perpendicular thereto is represented by ny, and the refractive index in the thickness direction of the film is represented by nz. The fast axis indicates an axial direction having a low refractive index in the film plane.

  Negative birefringence means that the stretching direction is the fast axis direction, and positive birefringence means that the direction perpendicular to the stretching direction is the fast axis direction.

  That is, in the uniaxial stretching of the polymer having negative birefringence, the refractive index in the stretching axis direction is small (fast axis: stretching direction), and in the uniaxial stretching of the polymer having positive birefringence, the axial direction perpendicular to the stretching axis. Has a small refractive index (fast axis: direction perpendicular to the stretching direction).

  Many polymers have positive birefringence. As a polymer having negative birefringence, there are acrylic resin and polystyrene. However, acrylic resin has a small retardation, and the properties as a retardation film are not sufficient. Polystyrene has a large photoelastic coefficient in the constant temperature region, so the phase difference changes due to slight stress, the problem of stability of the phase difference, the problem of optical properties such as the large wavelength dependence of the phase difference, and heat resistance However, it is not used at present.

  Here, the wavelength dependence of the phase difference means that the phase difference changes depending on the measurement wavelength. The phase difference measured at the wavelength of 450 nm (R450) and the phase difference measured at the wavelength of 550 nm (R550). The ratio can be expressed as R450 / R550. In general, a polymer having an aromatic structure has a strong tendency to increase R450 / R550, and the contrast and viewing angle characteristics in a low wavelength region are deteriorated.

  Furthermore, generally, the refractive index magnitude relationship of a polymer uniaxially stretched film exhibiting positive birefringence is ny> nx = nz, and the refractive index magnitude relationship of a biaxially stretched film is ny ≧ nx> nz, The uniaxially stretched film of the polymer exhibiting negative birefringence has a refractive index magnitude relationship of ny = nz> nx, and the biaxially stretched film has a refractive index magnitude relationship of nz> ny ≧ nz. The relationship of the refractive index of the film to the compensation of viewing angle characteristics of liquid crystal displays such as super twist nematic type liquid crystal display (STN-LCD) and in-plane alignment type liquid crystal display (IPS-LCD) and the antireflection film of organic EL display Although a film satisfying ny> nz> nx is required, it is difficult to achieve with a general stretched film as described above.

  A method for producing a film has been proposed in which a polymer having positive birefringence is used to increase the refractive index in the thickness direction of the film. One is a treatment method in which a heat-shrinkable film is bonded to one or both sides of a polymer film, the laminate is heated and stretched, and a shrinkage force is applied in the film thickness direction of the polymer film (see, for example, Patent Documents 1 to 3). ). In addition, a method of uniaxial stretching in a plane while applying an electric field to a polymer film has been proposed (for example, see Patent Document 4).

  In addition, a retardation film composed of fine particles having negative optical anisotropy and a transparent polymer has been proposed (see, for example, Patent Document 5).

  However, the methods proposed in Patent Documents 1 to 4 have a problem that productivity is inferior because the manufacturing process becomes very complicated. In addition, the control of the uniformity of the phase difference and the like is significantly more difficult than the control by the conventional stretching.

  When polycarbonate is used as the base film, the photoelastic coefficient at room temperature is large and the phase difference is changed by a slight stress, so that there is a problem in the stability of the phase difference. Furthermore, there is a problem that the wavelength dependence of the phase difference is large.

  The retardation film obtained in Patent Document 5 is a retardation film in which the refractive index is controlled by adding fine particles having negative optical anisotropy. There is a need for a retardation film that is complicated to manufacture such as compounding with molecules, has problems in the stability and uniformity of retardation, and does not require addition of fine particles.

  Moreover, the film which shows the negative birefringence which consists of a fumaric-acid diester type-resin is proposed (for example, refer patent document 6). Although the optical compensation film obtained in Patent Document 6 has a certain amount of out-of-plane retardation, since the film thickness is thick, the film productivity is inferior, and when laminated, the optical compensation film becomes thick. There exists a subject that the laminated | multilayer film tends to warp and the laminated | multilayer film which has a high out-of-plane phase difference also in a thin film are calculated | required.

Patent Document 7 discloses a fumaric acid diester copolymer having a storage elastic modulus (E ′) of 2.0 × 10 ⁷ Pa or more obtained from dynamic viscoelasticity measurement at 200 ° C. and a frequency of 10 Hz. Examples are copolymers of diisopropyl acid and di-n-butyl fumarate or bis (2-ethylhexyl) fumarate. Patent Document 7 is an application relating to a fumaric acid diester copolymer having excellent transparency, heat resistance and mechanical properties, and an optical film comprising the copolymer, particularly a plastic film substrate. As a resin for a film, a resin having higher retardation is required.

Japanese Patent No. 2818983 JP-A-5-297223 JP-A-5-323120 JP-A-6-88909 JP 2005-156862 A JP 2008-112141 A JP 2008-120551 A

  An object of the present invention is to provide a laminated film for optical compensation that has excellent optical compensation characteristics such as an NZ coefficient of 0.3 to 0.7, high light transmittance, and low haze.

  As a result of intensive studies to solve the above problems, the present inventors have found that a film using a specific fumaric acid diester resin and a laminated film for optical compensation in which a uniaxially stretched film is laminated can solve the above problems. The headline and the present invention were completed. That is, the present invention relates to an optical film in which a film using a fumaric acid diester resin containing a fumaric acid diester residue unit having a diisopropyl fumarate residue unit and an alkyl group having 1 or 2 carbon atoms and a uniaxially stretched film are laminated. Compensation laminated film, and the absolute value of the relationship between the film thickness of the film layer and the out-of-plane retardation (Rth) measured at a wavelength of 550 nm indicated by a predetermined formula is 4.0 nm / film thickness (μm) The in-plane retardation (Re) measured at a wavelength of 550 nm indicated by the predetermined formula of the uniaxially stretched film layer is 50 to 300 nm, and NZ shown by the predetermined formula of the laminated film for optical compensation A laminated film for optical compensation characterized by a coefficient of 0.3 to 0.7.

  Hereinafter, the present invention will be described in detail.

  The laminated film for optical compensation of the present invention is obtained by laminating a film using a specific fumaric acid diester resin and a uniaxially stretched film.

  The specific fumaric acid diester resin used in the film laminated on the optical compensation laminated film of the present invention is a fumaric acid diester residue having a diisopropyl fumarate residue unit and an alkyl group having 1 or 2 carbon atoms. It is a fumaric acid diester resin containing units.

  Here, the alkyl group having 1 or 2 carbon atoms in the fumaric acid diester residue unit having an alkyl group having 1 or 2 carbon atoms is independent, and examples thereof include a methyl group and an ethyl group. These may be substituted with a halogen group such as fluorine or chlorine; an ether group; an ester group or an amino group. Examples of the fumaric acid diester residue unit having an alkyl group having 1 or 2 carbon atoms include a dimethyl fumarate residue unit and a diethyl fumarate residue unit. These may be contained alone or in combination of two or more.

  Examples of the fumaric acid diester resin include diisopropyl fumarate / dimethyl fumarate copolymer resin, diisopropyl fumarate / diethyl fumarate copolymer resin, and the like.

  The fumaric acid diester resin may contain other monomer residue units as long as it does not exceed the scope of the present invention. Examples of other monomer residue units include styrene residue units, Styrene residue units such as α-methylstyrene residue units; (meth) acrylic acid residue units; (meth) methyl acrylate residue units, (meth) ethyl acrylate residue units, (meth) acrylate butyl (Meth) acrylic acid ester residue units such as residue units; vinyl ester residue units such as vinyl acetate residue units and vinyl propionate residue units; acrylonitrile residue units; methacrylonylyl residue units; methyl Vinyl ether residue units such as vinyl ether residue units, ethyl vinyl ether residue units, butyl vinyl ether residue units; N-methylmaleimide residue units, N-cyclohexylma N-substituted maleimide residue units such as imide residue units and N-phenylmaleimide residue units; olefin residue units such as ethylene residue units and propylene residue units; or di-n-butyl fumarate residue units 1 type, or 2 or more types chosen from fumaric acid diester residue units other than the said fumaric acid diester residue units, such as a bis (2-ethylhexyl) fumarate residue unit, can be mentioned.

  The blending ratio of the fumaric acid diester resin is preferably 50 to 99 mol% of diisopropyl fumarate residue units and 1 to 50 mol% of fumaric acid diester residue units having an alkyl group having 1 or 2 carbon atoms. Fumarate comprising 60 to 95 mol% diisopropyl fumarate residue units and 5 to 40 mol% fumaric acid diester residue units having an alkyl group having 1 or 2 carbon atoms. Acid diester resins are particularly preferred.

  The fumaric acid diester resin preferably has a standard polystyrene equivalent number average molecular weight of 10,000 to 250,000 obtained from an elution curve measured by gel permeation chromatography (hereinafter referred to as GPC).

  The fumaric acid diester resin may be produced by any method as long as the fumaric acid diester resin is obtained. For example, fumaric acid having diisopropyl fumarate and an alkyl group having 1 or 2 carbon atoms. Diesters can be produced by radical polymerization.

  For the radical polymerization, any of known polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization, precipitation polymerization, and emulsion polymerization can be employed.

  Examples of the polymerization initiator used in the radical polymerization method include benzoyl peroxide, lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-t-butyl peroxide, t-butyl cumyl peroxide, and dicumyl peroxide. Organic peroxides such as oxide, t-butylperoxyacetate, t-butylperoxybenzoate; 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2-butyronitrile), Examples thereof include azo initiators such as 2,2′-azobisisobutyronitrile, dimethyl-2, 2′-azobisisobutyrate, and 1,1′-azobis (cyclohexane-1-carbonitrile).

  And there is no restriction | limiting in particular as a solvent which can be used in a solution polymerization method, suspension polymerization method, precipitation polymerization method, emulsion polymerization method, For example, aromatic solvents, such as benzene, toluene, xylene; Methanol, ethanol, propanol, butanol, etc. Alcohol solvents; cyclohexane; dioxane; tetrahydrofuran; acetone; methyl ethyl ketone; dimethylformamide; isopropyl acetate; water and the like.

  Moreover, the polymerization temperature at the time of performing radical polymerization can be suitably set according to the decomposition temperature of a polymerization initiator, and generally it is preferable to carry out in the range of 30-150 degreeC.

  When the fumaric acid diester resin is used as a film, it is a film that has a high out-of-plane retardation even in a thin film and is excellent in optical properties such as wavelength dependency just by coating. In addition, this film is a film which has phase difference expression property, without adding microparticles | fine-particles.

  Since the film using the fumaric acid ester resin has a high out-of-plane retardation even in a thin film, the film thickness of the film layer using the fumaric acid diester resin and the wavelength represented by the following formula (a) 550 nm The absolute value of the relationship between the out-of-plane retardation (Rth) measured in (4) is 4.0 nm / film thickness (μm) or more, and preferably 4.5 nm / film thickness (μm) or more. The film thickness of the film using the fumarate ester resin is preferably 5 to 25 μm, more preferably 8 to 20 μm, and most preferably 10 to 15 μm.

Rth = ((nx1 + ny1) / 2−nz1) × d1 (a)
(In the formula, nx1 represents the refractive index in the fast axis direction in the film plane of the film layer using the fumarate ester resin, ny1 represents the refractive index in the orthogonal direction to nx1, and nz1 represents the thickness direction of the film. Refractive index is shown, d1 shows the thickness of a film.)
When the relationship between the film thickness and the out-of-plane retardation (Rth) measured at the wavelength of 550 nm indicated by the formula (a) is less than 4.0 nm / film thickness (μm) in absolute value, the film thickness is increased, The film productivity is poor, and the laminated film is warped or uneven.

  Moreover, since the laminated film for optical compensation of the present invention becomes an laminated film for optical compensation having more excellent optical characteristics, the out-of-plane retardation (Rth) measured at a wavelength of 550 nm represented by the above formula (a) is − It is preferably 50 to -300 nm, and particularly preferably -70 to -150 nm.

  In the film using the fumaric acid diester resin, an antioxidant is preferably blended in order to increase the thermal stability of the film itself or in the film itself. Examples of the antioxidant include hindered phenolic antioxidants, phosphorus antioxidants, and other antioxidants, and these antioxidants may be used alone or in combination. And since the antioxidant action is synergistically improved, it is preferable to use a hindered antioxidant and a phosphorus antioxidant in combination, and in that case, for example, with respect to 100 parts by weight of the hindered antioxidant, It is particularly preferable to use a phosphorus-based antioxidant mixed at 100 to 500 parts by weight. Moreover, as content of antioxidant, 0.01-10 weight part is preferable with respect to 100 weight part of fumaric acid diester type | system | group resin which comprises the film using this fumaric acid diester type-resin, Especially 0.5 part is preferable. -1 part by weight is preferred.

  Furthermore, the film using the fumaric acid diester resin may contain, for example, an ultraviolet absorber such as benzotriazole, benzophenone, triazine, or benzoate as the ultraviolet absorber.

  The film using the fumaric acid diester resin is within the range not exceeding the gist of the invention, other polymers, surfactants, polymer electrolytes, conductive complexes, inorganic fillers, pigments, antistatic agents, antiblocking agents, A lubricant or the like may be blended.

  There is no restriction | limiting in particular as a manufacturing method of the film using this fumaric-acid diester type-resin, For example, it can manufacture by methods, such as a solution cast method and a melt cast method.

  The solution casting method is a method of obtaining a film by casting a solution in which a fumaric acid diester resin is dissolved in a solvent (hereinafter referred to as a dope) on a support substrate and then removing the solvent by heating or the like. In this case, as a method for casting the dope on the support substrate, for example, a T-die method, a doctor blade method, a bar coater method, a roll coater method, a lip coater method, or the like is used. Particularly, industrially, a method of continuously extruding a dope from a die onto a belt-like or drum-like support substrate is most common. Examples of the support substrate used include a glass substrate, a metal substrate such as stainless steel and ferrotype, and a film such as polyethylene terephthalate. In the solution casting method, when forming a film having high transparency and excellent thickness accuracy and surface smoothness, the solution viscosity of the dope is a very important factor, preferably 10 to 20000 cPs. It is preferable that it is 100-10000 cPs.

  As described above, the coating thickness (film thickness) of the fumaric acid diester resin obtained by this film production method is preferably 5 to 25 μm after drying, more preferably 8 to 20 μm, and particularly preferably 10 to 15 μm. It is.

  The melt casting method is a molding method in which a fumaric acid diester resin is melted in an extruder, extruded into a film form from a slit of a T die, and then cooled while being cooled with a roll or air.

  The uniaxially stretched film laminated on the optical compensation laminated film of the present invention is a film obtained by stretching a polymer exhibiting positive birefringence in at least the film length direction or the film width direction, and exhibits positive birefringence. Examples of the polymer include cellulose resin, cyclic polyolefin, acrylic resin, polyester, polycarbonate, polyamide, polyimide, and the like. Of these, cellulose resins and cyclic polyolefins are preferred because of their low retardation and wavelength dependency. Examples of the cellulose resin include cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose propionate, and cellulose butyrate. Examples of the cyclic polyolefin include a copolymer of norbornene and ethylene, a hydrogenated product of a ring-opening polymer of norbornene, and the like. You may add a plasticizer, a ultraviolet absorber, etc. to these resin. The uniaxially stretched film can be produced by forming the polymer exhibiting positive birefringence into a film by solution casting or melt extrusion, and then stretching it at least uniaxially by a roll, a tenter or the like. As for the film thickness of a uniaxially stretched film, 10-200 micrometers and 20-150 micrometers are preferable. The draw ratio is set depending on the target phase difference and the like, but is preferably 1.1 to 5 times and 1.2 to 2 times. The stretching temperature is preferably a polymer glass transition temperature of −30 to + 30 ° C., particularly preferably −20 to + 20 ° C.

  The in-plane retardation (Re) measured at a wavelength of 550 nm represented by the following formula (b) of the uniaxially stretched film layer in the present invention is 50 to 300 nm, and particularly preferably 80 to 260 nm.

Re = (ny2-nx2) * d2 (b)
(In the formula, nx2 represents the refractive index in the fast axis direction in the film plane of the uniaxially stretched film layer, ny2 represents the refractive index in the orthogonal direction to nx2, and d2 represents the thickness of the uniaxially stretched film.)
When the in-plane retardation (Re) is less than 50 nm, the optical compensation performance is insufficient, and when it exceeds 300 nm, color misregistration or the like becomes large.

  In the laminated film for optical compensation of the present invention, the NZ coefficient represented by the following formula (c) is 0.3 to 0.7, and preferably 0.4 to 0.6.

NZ coefficient = (ny3-nz3) / (ny3-nx3) (c)
(Wherein nx3 represents the average refractive index in the fast axis direction in the film plane of the optical compensation laminated film, ny3 represents the average refractive index in the direction perpendicular to nx3, and nz3 represents the thickness direction of the optical compensation laminated film) The average refractive index of.
When the NZ coefficient satisfies 0.3 to 0.7, a laminated film for optical compensation excellent in viewing angle compensation performance such as STN-LCD and IPS-LCD and antireflection characteristics such as organic EL display is obtained. .

  The wavelength dependence of the phase difference can be expressed as a ratio R450 / R550 of the phase difference (R450) measured at a wavelength of 450 nm and the phase difference (R550) measured at a wavelength of 550 nm. In the laminated film for optical compensation of the present invention, since the image quality of the display, particularly the color change is small and the contrast is improved, the R450 / R550 is preferably 1.1 or less, more preferably 1.08 or less. 05 or less is preferable.

  The laminated film for optical compensation of the present invention has good image quality characteristics when used in a liquid crystal display element, so that the light transmittance is preferably 85% or more, particularly 90% or more. Is preferred. Further, the haze (cloudiness) of the laminated film for optical compensation is preferably 2% or less, and particularly preferably 1% or less.

  The laminated film for optical compensation of the present invention may be laminated with a glass substrate as a base material and other optical films in addition to the above-described film using a fumarate ester resin and a uniaxially stretched film.

  The laminated film for optical compensation of the present invention can be laminated with a polarizing plate and used as a circular or elliptical polarizing plate, or laminated with a polarizer made of polyvinyl alcohol / iodine or the like to form a polarizing plate. Is possible. Furthermore, it can also laminate | stack with the laminated films for optical compensation of this invention, or another retardation film.

  The laminated film for optical compensation of the present invention can be produced by laminating a film using the above fumarate ester resin and a uniaxially stretched film, or casting the fumarate ester resin on the uniaxially stretched film. Can also be manufactured.

  The present invention relates to a laminated film for optical compensation, and more specifically, a film using a fumarate ester resin having a high out-of-plane retardation even in a thin film and a uniaxially stretched film are laminated, and the NZ coefficient is The present invention relates to a laminated film for optical compensation of 0.3 to 0.7.

  The laminated film for optical compensation of the present invention is a laminated film for optical compensation in which a film using a fumarate ester resin having a high out-of-plane retardation even in a thin film and a uniaxially stretched film are laminated, and the NZ coefficient is 0. It is excellent in optical compensation characteristics such as high light transmittance and low haze.

It is a figure which shows the change of the refractive index ellipsoid by extending | stretching.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.

  In addition, the various physical properties shown by an Example were measured with the following method.

~ Composition of fumaric acid diester resin ~
Using a nuclear magnetic resonance measuring apparatus (manufactured by JEOL, trade name JNM-GX270), it was determined by proton nuclear magnetic resonance spectroscopy ( ¹ H-NMR) spectrum analysis.

~ Measurement of number average molecular weight ~
Using a gel permeation chromatography (GPC) apparatus (manufactured by Tosoh Corporation, trade name CO-8011 (equipped with column GMHHR-H)), tetrahydrofuran was used as a solvent, and measurement was performed at 40 ° C. to obtain a standard polystyrene equivalent value.

~ Transparency evaluation method ~
The total light transmittance and haze of the film were measured using a haze meter (trade name NDH5000, manufactured by Nippon Denshoku Industries Co., Ltd.).

~ Measurement of refractive index and average refractive index ~
The refractive index was measured according to JIS K 7142 (1981 version) using an Abbe refractometer (manufactured by Atago). The average refractive index was calculated from the refractive index and film thickness of each film.

-Measurement of out-of-plane retardation (Rth) of film, in-plane retardation (Re) of uniaxially stretched film, and NZ coefficient of laminated film for optical compensation-
Measurement was performed using a fully automatic birefringence meter (trade name KOBRA-WR, manufactured by Oji Scientific Instruments).

Production Example 1 (Production of Fumarate Diester Resin (Diisopropyl Fumarate / Diethyl Fumarate Copolymer Resin))
In a 1 L autoclave equipped with a stirrer, a condenser tube, a nitrogen inlet tube and a thermometer, 2 g of hydroxypropyl methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd., trade name Metrose 60SH-50), 600 g of distilled water, 365 g of diisopropyl fumarate, 35 g of diethyl fumarate, Then, 3 g of t-butyl peroxypivalate as a polymerization initiator was added, nitrogen bubbling was performed for 1 hour, and then the suspension was kept at 45 ° C. for 24 hours while stirring at 400 rpm to perform radical suspension polymerization. After cooling to room temperature, the resulting suspension containing polymer particles was filtered off and washed with distilled water and methanol to obtain a fumaric acid diester resin (yield: 65%).

The number average molecular weight of the obtained fumaric acid diester resin was 132,000. Further, ¹ H-NMR measurement confirmed that the resin composition was diisopropyl fumarate residue unit / diethyl fumarate residue unit = 91/9 (mol%).

Production Example 2 (Production of Fumarate Diester Resin (Diisopropyl Fumarate / Diethyl Fumarate Copolymer Resin))
In a 1 L autoclave equipped with a stirrer, a condenser tube, a nitrogen inlet tube and a thermometer, 2 g of hydroxypropyl methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd., trade name Metrose 60SH-50), 600 g of distilled water, 330 g of diisopropyl fumarate, 70 g of diethyl fumarate, Then, 3 g of t-butyl peroxypivalate as a polymerization initiator was added, nitrogen bubbling was performed for 1 hour, and then the suspension was kept at 50 ° C. for 24 hours while stirring at 400 rpm to perform radical suspension polymerization. After cooling to room temperature, the resulting suspension containing polymer particles was filtered off and washed with distilled water and methanol to obtain a fumaric acid diester resin (yield: 75%).

The number average molecular weight of the obtained fumaric acid diester resin was 120,000. Further, ¹ H-NMR measurement confirmed that the resin composition was diisopropyl fumarate residue unit / diethyl fumarate residue unit = 84/16 (mol%).

Production Example 3 (Production of Fumarate Diester Resin (Diisopropyl Fumarate / Diethyl Fumarate Copolymer Resin))
In a 1 L autoclave equipped with a stirrer, a condenser tube, a nitrogen introduction tube and a thermometer, 2 g of hydroxypropyl methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd., trade name Metrose 60SH-50), 600 g of distilled water, 255 g of diisopropyl fumarate, 145 g of diethyl fumarate, Then, 3 g of t-butyl peroxypivalate as a polymerization initiator was added, nitrogen bubbling was performed for 1 hour, and then the suspension was held at 45 ° C. for 36 hours while stirring at 400 rpm to perform radical suspension polymerization. After cooling to room temperature, the resulting suspension containing polymer particles was filtered and washed with distilled water and methanol to obtain a fumaric acid diester resin (yield: 60%).

The number average molecular weight of the obtained fumaric acid diester resin was 100,000. Further, ¹ H-NMR measurement confirmed that the resin composition was diisopropyl fumarate residue unit / diethyl fumarate residue unit = 70/30 (mol%).

Production Example 4 (Production of Fumarate Diester Resin (Diisopropyl Fumarate / Dimethyl Fumarate Copolymer Resin))
In a 1 L autoclave equipped with a stirrer, a condenser tube, a nitrogen inlet tube and a thermometer, 3 g of hydroxypropyl methylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd., trade name Metrose 60SH-50), 600 g of distilled water, 380 g of diisopropyl fumarate, 20 g of dimethyl fumarate, Then, 3 g of t-butyl peroxypivalate as a polymerization initiator was added, nitrogen bubbling was performed for 1 hour, and then the suspension was kept at 50 ° C. for 24 hours while stirring at 400 rpm to perform radical suspension polymerization. After cooling to room temperature, the resulting suspension containing polymer particles was filtered off and washed with distilled water and methanol to obtain a fumaric acid diester resin (yield: 76%).

The number average molecular weight of the obtained fumaric acid diester resin was 120,000. Further, ¹ H-NMR measurement confirmed that the resin composition was diisopropyl fumarate residue unit / dimethyl fumarate residue unit = 94/6 (mol%).

Production Example 5 (Production of fumaric acid diester resin (diisopropyl fumarate / di-n-butyl fumarate copolymer resin))
In a 1 L autoclave equipped with a stirrer, a condenser tube, a nitrogen inlet tube and a thermometer, 1.6 g of hydroxypropylmethylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd., trade name Metrose 60SH-50), 520 g of distilled water, 230 g of diisopropyl fumarate, difumarate di After adding 50 g of n-butyl and 2.1 g of t-butyl peroxypivalate which is a polymerization initiator and carrying out nitrogen bubbling for 1 hour, the suspension is kept at 50 ° C. for 24 hours while stirring at 400 rpm. Polymerization was performed. After cooling to room temperature, the resulting suspension containing polymer particles was filtered off and washed with distilled water and methanol to obtain a fumaric acid diester resin (yield: 80%).

The number average molecular weight of the obtained fumaric acid diester resin was 150,000. Further, ¹ H-NMR measurement confirmed that the resin composition was diisopropyl fumarate residue unit / di-n-butyl fumarate residue unit = 87/13 (mol%).

Production Example 6 (Production of Fumarate Diester Resin (Diisopropyl Fumarate / Bis-2-ethylhexyl Fumarate Copolymer Resin))
In a 1 L autoclave equipped with a stirrer, a condenser tube, a nitrogen inlet tube and a thermometer, 1.6 g of hydroxypropylmethylcellulose (manufactured by Shin-Etsu Chemical Co., Ltd., trade name Metrose 60SH-50), 520 g of distilled water, 196 g of diisopropyl fumarate, bis of fumarate 84 g of 2-ethylhexyl and 1.9 g of t-butyl peroxypivalate as a polymerization initiator were added, nitrogen bubbling was performed for 1 hour, and then the suspension was kept at 50 ° C. for 24 hours while stirring at 400 rpm. Polymerization was performed. After cooling to room temperature, the resulting suspension containing polymer particles was filtered off and washed with distilled water and methanol to obtain a fumaric acid diester resin (yield: 66%).

The number average molecular weight of the obtained fumaric acid diester resin was 86,000. Further, ¹ H-NMR measurement confirmed that the resin composition was diisopropyl fumarate residue unit / bis-2-ethylhexyl fumarate residue unit = 84/16 (mol%).

Production Example 7 (Production of uniaxially stretched film (cellulose acetate propionate))
As a cellulose resin, 50 g of cellulose acetate propionate (Eastman Chemical) was dissolved in 250 g of methylene chloride, and the resulting solution was cast on a PET film substrate using a bar coater and dried at 40 ° C. for 5 minutes. The film was dried at 60 ° C. for 5 minutes and at 120 ° C. for 5 minutes to obtain a film having a thickness of 110 μm. The obtained film was peeled from the PET film substrate, and uniaxially stretched 1.8 times at 130 ° C. using a stretching machine (thickness 82 μm). The in-plane retardation (Re) of the obtained uniaxially stretched film was 139 nm (nx2 = 1.4803, ny2 = 1.4820).

Production Example 8 (Production of uniaxially stretched film (cellulose acetate butyrate))
As a cellulose resin, 50 g of cellulose acetate butyrate (manufactured by Eastman Chemical) was dissolved in 250 g of methylene chloride, and the resulting solution was cast on a PET film substrate using a bar coater and dried at 40 ° C. for 5 minutes. The film was dried at 60 ° C. for 5 minutes and at 120 ° C. for 5 minutes to obtain a film having a thickness of 160 μm. The obtained film was peeled from the PET film substrate and uniaxially stretched 2.0 times at 125 ° C. using a stretching machine (thickness 113 μm). The in-plane retardation (Re) of the obtained uniaxially stretched film was 215 nm (nx2 = 1.4720, ny2 = 1.4739).

Production Example 9 (Production of uniaxially stretched film (cyclic polyolefin))
As a cyclic polyolefin, 100 g of 8-methyl-8-carboxymethyltetracyclo-3-dodecene, 400 mL of 1,2-dichloroethane, 0.76 g of a molecular weight regulator, 0.76 g of a molecular weight regulator, and WCl6 as a catalyst in a nitrogen-substituted reactor. 18.32 mL of 0.05 M / L chlorobenzene solution, 13.74 mL of 1,2-dichloroethane solution of 0.1 M / L paraaldehyde and 7.4 mL of 0.5 M / L toluene solution of triisobutylaluminum Was added and reacted at 60 ° C. for 10 hours to obtain 90 g of a polymer. 80 g of this polymer was dissolved in 1600 mL of toluene, 100 g of nickel naphthenate and 256 mL of a toluene solution of triethylaluminum having a concentration of 1 M / L were added, hydrogen gas pressure was 50 kg / cm 2, and hydrogenation reaction was performed at 60 ° C. for 15 hours. The obtained polymer was poured into a large excess of hydrochloric acid acidic methanol, the catalyst was decomposed and removed, the polymer was recovered and dried, and a hydrogenated 8-methyl-8-carboxymethyltetracyclo-3-dodecene ring-opened polymer was obtained. Obtained. 50 g of the obtained polymer was dissolved in 250 g of methylene chloride, and the resulting solution was cast on a PET film substrate using a bar coater and dried at 40 ° C. for 5 minutes, 60 ° C. for 5 minutes, and 120 ° C. for 5 minutes. The film was dried to obtain a film having a thickness of 100 μm. The obtained film was peeled from the PET film substrate, and uniaxially stretched 1.6 times at 160 ° C. using a stretching machine (thickness 79 μm). The in-plane retardation (Re) of the obtained uniaxially stretched film was 119 nm (nx2 = 1.5087, ny2 = 1.5102).

Example 1
The fumaric acid diester resin obtained in Production Example 1 was dissolved in methyl isobutyl ketone to give a 15% by weight resin solution, cast on a polyethylene terephthalate film with a coater, and dried at 130 ° C. for 10 minutes to obtain a thickness. A film using 15 μm fumaric acid diester resin was obtained.

  The obtained film has an out-of-plane retardation (Rth) of −81 nm (nx1 = 1.4688, ny1 = 1.4688, nz1 = 1.4742), and the absolute value of the relationship between the film thickness and the out-of-plane retardation. Was 5.4 nm / film thickness (μm).

A laminated film was produced by pasting the obtained film on the uniaxially stretched film produced in Production Example 7 with an acrylic adhesive, and the characteristics were evaluated. The obtained results are shown in Table 1.

  From these results, the obtained laminated film has a target NZ coefficient, high light transmittance, low haze, and excellent optical properties such as low retardation wavelength dependence. It was suitable as a film.

Example 2
The methyl isobutyl ketone solution of the fumaric acid diester resin obtained in Example 1 was cast on the uniaxially stretched film produced in Production Example 7 using a coater, and dried at 130 ° C. for 10 minutes to produce a laminated film. The thickness of the film layer using the fumaric acid diester resin of the laminated film is 15 μm, and the out-of-plane retardation (Rth) is −81 nm (nx1 = 1.4688, ny1 = 1.4688, nz1 = 1.742). ), The absolute value of the relationship between the film thickness and the out-of-plane retardation was 5.4 nm / film thickness (μm).

  The characteristics of the obtained laminated film were evaluated. The obtained results are shown in Table 1. The obtained laminated film had good adhesiveness between the film made of a fumaric acid diester resin and the uniaxially stretched film, and no warpage was observed.

  From these results, the obtained laminated film has a target NZ coefficient, high light transmittance, low haze, and excellent optical properties such as low retardation wavelength dependence. It was suitable as a film.

Example 3
The fumaric acid diester resin obtained in Production Example 2 was dissolved in methyl isobutyl ketone to give a 15% by weight resin solution, cast on a polyethylene terephthalate film using a coater, and dried at 130 ° C. for 10 minutes. A film using a fumaric acid diester resin having a thickness of 14 μm was obtained.

  The obtained film has an out-of-plane retardation (Rth) of −71 nm (nx1 = 1.6944, ny1 = 1.4694, nz1 = 1.4745), and the absolute value of the relationship between the film thickness and the out-of-plane retardation. Was 5.1 nm / film thickness (μm).

  A laminated film was produced by pasting the obtained film on the uniaxially stretched film produced in Production Example 7 with an acrylic adhesive, and the characteristics were evaluated. The obtained results are shown in Table 1.

  From these results, the obtained laminated film has a target NZ coefficient, high light transmittance, low haze, and excellent optical properties such as low retardation wavelength dependence. It was suitable as a film.

Example 4
Dissolve the fumaric acid diester resin obtained in Production Example 3 in a methyl isobutyl ketone solvent to give a 15% by weight resin solution, cast on a polyethylene terephthalate film using a coater, and dry at 130 ° C. for 10 minutes. Thus, a film using a fumarate diester resin having a thickness of 15 μm was obtained.

  The obtained film has an out-of-plane retardation (Rth) of −68 nm (nx1 = 1.4720, ny1 = 1.4720, nz1 = 1.4765), and the absolute value of the relationship between the film thickness and the out-of-plane retardation. Was 4.5 nm / film thickness (μm).

  A laminated film was produced by pasting the obtained film on the uniaxially stretched film produced in Production Example 7 with an acrylic adhesive, and the characteristics were evaluated. The obtained results are shown in Table 1.

  From these results, the obtained laminated film has a target NZ coefficient, high light transmittance, low haze, and excellent optical properties such as low retardation wavelength dependence. It was suitable as a film.

Example 5
The fumaric acid diester resin obtained in Production Example 4 was dissolved in methyl isobutyl ketone to give a 15% by weight resin solution, cast on a polyethylene terephthalate film with a coater, and dried at 130 ° C. for 10 minutes to obtain a thickness. A film using 15 μm fumaric acid diester resin was obtained.

  The obtained film has an out-of-plane retardation (Rth) of −86 nm (nx1 = 1.4696, ny1 = 1.4696, nz1 = 1.4753), and the absolute value of the relationship between the film thickness and the out-of-plane retardation. Was 5.7 nm / film thickness (μm).

  A laminated film was produced by pasting the obtained film on the uniaxially stretched film produced in Production Example 8 with an acrylic adhesive, and the characteristics were evaluated. The obtained results are shown in Table 1.

  From these results, the obtained laminated film has a target NZ coefficient, high light transmittance, low haze, and excellent optical properties such as low retardation wavelength dependence. It was suitable as a film.

Example 6
The fumaric acid diester resin obtained in Production Example 4 was dissolved in methyl isobutyl ketone to give a 15% by weight resin solution, cast on a polyethylene terephthalate film with a coater, and dried at 130 ° C. for 10 minutes to obtain a thickness. A film using 11 μm fumaric acid diester resin was obtained.

  The obtained film has an out-of-plane retardation (Rth) of −63 nm (nx1 = 1.4696, ny1 = 1.4696, nz1 = 1.4753), and the absolute value of the relationship between the film thickness and the out-of-plane retardation. Was 5.7 nm / film thickness (μm).

  A laminated film was produced by pasting the obtained film on the uniaxially stretched film produced in Production Example 9 with an acrylic adhesive, and the characteristics were evaluated. The obtained results are shown in Table 1.

  From these results, the obtained laminated film has a target NZ coefficient, high light transmittance, low haze, and excellent optical properties such as low retardation wavelength dependence. It was suitable as a film.

Comparative Example 1
The fumaric acid diester resin obtained in Production Example 5 was dissolved in a methyl isobutyl ketone solvent to give a 20 wt% resin solution, which was cast on a polyethylene terephthalate film by a coater, 10 minutes at 70 ° C., 10 minutes at 130 ° C. By partially drying, a film having a thickness of 15 μm was obtained.

  Since the obtained film did not use the fumaric acid diester resin containing the diisopropyl fumarate residue unit and the fumaric acid diester residue unit having an alkyl group having 1 or 2 carbon atoms, the out-of-plane retardation (Rth) is -35 nm (nx1 = 1.4693, ny1 = 1.4693, nz1 = 1.4716), and the absolute value of the relationship between the film thickness and the out-of-plane retardation is as small as 2.3 nm / film thickness (μm). Met.

  A laminated film was produced by pasting the obtained film on the uniaxially stretched film produced in Production Example 7 with an acrylic adhesive, and the characteristics were evaluated. The obtained results are shown in Table 1.

  From these results, since the obtained laminated film did not have the target NZ coefficient, it was unsuitable as a laminated film for optical compensation.

Comparative Example 2
The fumaric acid diester resin obtained in Production Example 6 was dissolved in a toluene / methyl ethyl ketone = 50/50 mixed solvent to form a 20% by weight resin solution, which was cast on a polyethylene terephthalate film by a coater, and then at 70 ° C. for 15 minutes. A film having a thickness of 15 μm was obtained by drying.

  Since the obtained film did not use the fumaric acid diester resin containing the diisopropyl fumarate residue unit and the fumaric acid diester residue unit having an alkyl group having 1 or 2 carbon atoms, the out-of-plane retardation (Rth) is -23 nm (nx1 = 1.46889, ny1 = 1.46889, nz1 = 1.4704), and the absolute value of the relationship between the film thickness and the out-of-plane retardation is as small as 1.5 nm / film thickness (μm). Met.

  A laminated film was produced by pasting the obtained film on the uniaxially stretched film produced in Production Example 7 with an acrylic adhesive, and the characteristics were evaluated. The obtained results are shown in Table 1.

  From these results, since the obtained laminated film did not have the target NZ coefficient, it was unsuitable as a laminated film for optical compensation.

  nx: Refractive index in the fast axis direction in the film plane.

  ny: Refractive index in the film in-plane direction orthogonal to nx.

  nz: The refractive index in the thickness direction of the film.

Claims (4)

A film using a fumaric acid diester resin containing 1 to 16 mol% of a fumaric acid diester residue unit having 84 to 99 mol% of a diisopropyl fumarate residue unit and an alkyl group having 1 or 2 carbon atoms is laminated with a uniaxially stretched film. An optical compensation laminated film, and the absolute value of the relationship between the film thickness of the film layer and the out-of-plane retardation (Rth) measured at a wavelength of 550 nm represented by the following formula (a): 5.1 nm / The film thickness (μm) or more, the in-plane retardation (Re) measured at a wavelength of 550 nm indicated by the following formula (b) of the uniaxially stretched film layer is 50 to 300 nm, and a laminated film for optical compensation An NZ coefficient represented by the following formula (c) is 0.3 to 0.7, and a laminated film for optical compensation.
Rth = ((nx1 + ny1) / 2−nz1) × d1 (a)
(In the formula, nx1 represents the refractive index in the fast axis direction in the film plane of the film layer using the fumarate ester resin, ny1 represents the refractive index in the orthogonal direction to nx1, and nz1 represents the thickness direction of the film. Refractive index is shown, d1 shows the thickness of a film.)
Re = (ny2-nx2) * d2 (b)
(In the formula, nx2 represents the refractive index in the fast axis direction in the film plane of the uniaxially stretched film layer, ny2 represents the refractive index in the orthogonal direction to nx2, and d2 represents the thickness of the uniaxially stretched film.)
NZ coefficient = (ny3-nz3) / (ny3-nx3) (c)
(Wherein nx3 represents the average refractive index in the fast axis direction in the film plane of the optical compensation laminated film, ny3 represents the average refractive index in the direction perpendicular to nx3, and nz3 represents the thickness direction of the optical compensation laminated film) The average refractive index of. The laminated film for optical compensation according to claim 1, wherein the film layer using the fumaric acid diester resin has a thickness of 5 to 25 μm. The out-of-plane retardation (Rth) measured at a wavelength of 550 nm represented by the following formula (a) of a film layer using a fumaric acid diester resin is -50 to -300 nm. Item 3. The laminated film for optical compensation according to Item 2.
Rth = ((nx1 + ny1) / 2−nz1) × d1 (a)
(In the formula, nx1 represents the refractive index in the fast axis direction in the film plane of the film layer using the fumarate-based resin, ny1 represents the refractive index in the perpendicular direction to nx1, and nz1 represents the refractive index in the film thickness direction. And d1 indicates the thickness of the film.) The ratio (R450 / R550) of the retardation (R450) in the optical compensation laminated film surface measured at a wavelength of 450 nm to the retardation (R550) in the optical compensation laminated film surface measured at 550 nm is 1.1 or less. The laminated film for optical compensation according to any one of claims 1 to 3, wherein:

Images