JPH08160222A - Substrate for optical compensating film - Google Patents

Abstract

PURPOSE: To obtain a substrate for optical compensating film having dimensional stability with excellent optical properties suitable for optical compensating film. CONSTITUTION: This substrate is composed of an aromatic polycarbonate, which is a copolymer of bisphenol A copolymerized with a bisphenol component constituted of a non-bisphenol A structure in the copolymerization ratio of 5-30mol% per bisphenol A and has >=30000 average molecular weight and >=150 deg.C glass transition point. The polymer film having intra-plane optical isotropy is used as the substrate for the optical compensating film obtained by forming the optical layer having optical compensating function on the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical compensation film in an optical compensation film formed by forming an optical layer having an optical compensation function, which is used for realizing a wide viewing angle and a high contrast in a liquid crystal display device or the like. And a substrate for forming the.

[0002]

2. Description of the Related Art Liquid crystal display elements have the great advantages of being thin and lightweight and of low power consumption. Therefore, it has been actively used in recent years in display devices such as personal computers, word processors, and portable electronic notebooks. Many principles of liquid crystal display devices have been proposed. Under such circumstances, most of the liquid crystal display elements that are currently widespread use twisted nematic liquid crystal. The display method using such a liquid crystal is roughly classified into a birefringence mode (hereinafter, STN method) and an optical rotation mode (hereinafter, TN method).

Since the STN system has steep electro-optical characteristics, it can be driven by a simple matrix. Therefore, it is supplied to the market at a relatively low price. However, in such a system, the incident light linearly polarized through the polarizing plate becomes elliptically polarized light due to birefringence by the liquid crystal cell. Therefore, when it is viewed through a polarizing plate, there is a problem that the display looks colored.

Therefore, in order to return the elliptically polarized light after passing through the liquid crystal cell to the linearly polarized light and prevent coloring, an F-STN (film compensation type STN) system in which an optical compensation film made of a stretched film or the like is interposed between the liquid crystal cell and the polarizing plate. Is proposed. An optical compensation film using this stretched film,
D-ST having a configuration in which a conventional compensation cell is overlaid on a drive cell
Since it is cheaper than N (double-cell STN), it has become widely used.

On the other hand, the TN method is excellent in that it has a high response speed of several tens of milliseconds, a high contrast ratio and a good gradation display property. Therefore, it is used as a liquid crystal display device in which a switching element such as a thin film transistor is provided for each pixel, in applications such as a liquid crystal television that requires high definition and high speed.

[0006]

The stretched film type optical compensation film is characterized in that it compensates the retardation of liquid crystal. However, with the recent demand for higher image quality in STN, not only the compensation of the phase difference but also the optical compensation film, the optical dispersion according to the wavelength, the liquid crystal phase difference change compensation according to the temperature, the refractive index control in the film thickness direction, etc. Various characteristics have come to be required. Solving those problems 1
As one means, one using a polymer liquid crystal having an optical compensation function has been proposed. Since the polymer liquid crystal that exhibits such optical characteristics is generally very thin, it is difficult to handle it as a film by itself, and it requires an optically isotropic and transparent substrate.

In addition, T combined with a switching element
The N-type liquid crystal display element also has a problem that it has a viewing angle dependency that the contrast ratio changes depending on the viewing direction. As a method for improving the viewing angle dependence, the three-dimensional refractive index (nx, ny, n
A method has been proposed in which z) is set to nx = ny ≠ nz to compensate only the phase difference of light obliquely entering the liquid crystal display device. As such an optical compensation film, for example, a method of using an inorganic layered compound has been proposed, but it is difficult to handle this inorganic layered compound alone as a film, and it requires an optically isotropic and transparent substrate.

As described above, in addition to the stretched film type optical compensation film, an optical compensation film having a higher optical function requires an optically isotropic and transparent substrate. Furthermore, even when used in liquid crystal display devices, etc., the dimensional stability withstands heat treatment in the manufacturing process,
Dimensional stability and durability that can withstand the operating temperature environment
There is a demand for such substrates. However, at present, no conventional substrate for an optical compensation film has such a characteristic.

It is an object of the present invention to solve the above problems and obtain a substrate for an optical compensation film having good optical characteristics suitable for the optical compensation film and having dimensional stability. That is, as the optical characteristics, the retardation value is 20 nm or less, the absolute value of the slow axis angle distribution is 15 ° or less, and the haze value is 0.8% or less, while the dimensional stability is 120 ° C. It is an object of the present invention to obtain an optical compensation film substrate having the characteristics that it is 0.10% or less even after heat treatment for 1 hour and 0.15% or less even after heat treatment at 150 ° C. for 30 minutes.

[0010]

The substrate for an optical compensation film of the present invention comprises a bisphenol component having a non-bisphenol A skeleton and a bisphenol A copolymerization ratio of 5 to 5.
An in-plane optically isotropic polymer film made of an aromatic polycarbonate having an average molecular weight of 30,000 or more and a glass transition temperature of 150 ° C. or more, which is a copolymer of bisphenol A copolymerized at 30 mol%, is formed on a substrate. It is characterized in that it is used as a substrate in an optical compensation film formed by forming an optical layer having an optical compensation function.

Alternatively, in the substrate for an optical compensation film of the present invention, a copolymerization ratio of terephthalic acid, isophthalic acid or a mixture thereof with bisphenol A is 5 to 45 m.
The in-plane optically isotropic polymer film made of an aromatic polyester carbonate having an average molecular weight of 30,000 or more and a glass transition temperature of 150 ° C. or more, which is a copolymer of bisphenol A copolymerized with ol%, is used as a substrate. A substrate for an optical compensation film, which is characterized in that it is used as a substrate in an optical compensation film having an optical layer having an optical compensation function thereon, or a substrate for an optical compensation film of the present invention is a bisphenol component composed of a perhydroisophorone skeleton or a fluorene skeleton, and Aromatic terephthalic acid, isophthalic acid, or a mixture thereof, which is copolymerized with bisphenol A at a copolymerization ratio of 5 to 30 mol% and has an average molecular weight of 30,000 or more and a glass transition temperature of 150 ° C or more. Polyester carbonate The Rimmer films, characterized by using as the substrate.

By the way, the optical compensation film substrate of the present invention is required to have dimensional stability as heat resistance. This is because the dimensional stability that can withstand high-temperature treatment in the manufacturing process of forming an optical compensation layer such as a polymer liquid crystal on the substrate, and the size under a temperature environment when used in a liquid crystal display device or the like. Stability. And this dimensional stability,
There is a demand to achieve it while providing the required optical properties.

When the physical properties required for the substrate for the optical compensation film to satisfy the required characteristics were examined,
It has been found that the required properties are satisfied when the glass transition temperature of the polycarbonate is 150 ° C. or higher. That is, the glass transition temperature of the substrate for the optical compensation film is 15
If the temperature is 0 ° C. or higher, it can sufficiently withstand the step of coating an optical layer such as a polymer liquid crystal on a substrate and the heat treatment step in the optical compensation film manufacturing process. Furthermore, it can withstand the environment when used in a liquid crystal display device or the like.

For that purpose, the substrate for the optical compensation film comprises a bisphenol component having a non-bisphenol A skeleton and a bisphenol A copolymerization ratio of 5 to 30 m.
It is necessary to be an in-plane optically isotropic polymer film made of an aromatic polycarbonate having an average molecular weight of 30,000 or more, which is a copolymer of bisphenol A copolymerized with ol%.

Alternatively, the substrate for the optical compensation film contains terephthalic acid, isophthalic acid, or a mixture thereof.
An in-plane optically isotropic polymer film comprising an aromatic polyester carbonate having an average molecular weight of 30,000 or more, which is a copolymer of bisphenol A copolymerized with bisphenol A at a copolymerization ratio of 5 to 45 mol%. It is necessary to have it.

Alternatively, the optical compensation film substrate is obtained by copolymerizing a bisphenol component having a perhydroisophorone skeleton or a fluorene skeleton, and terephthalic acid or isophthalic acid or a mixture thereof with a bisphenol A copolymerization ratio of 5 to 30 mol%. In addition, it is necessary to use a polymer film of an aromatic polyester carbonate having an average molecular weight of 30,000 or more, which is made of a bisphenol A copolymer.

At that time, when the average molecular weight is less than 30,000,
It is difficult to set the glass transition temperature to 150 ° C. or higher, resulting in a problem in thermal durability. The average molecular weight in the present invention is a number average molecular weight,
It is determined by a known measuring means such as GPC. Here, only the maximum distribution of the number average molecular weight is determined as the average molecular weight, and there is no restriction on the distribution state of the molecular weight.

The above-mentioned aromatic polycarbonate copolymer has 5 repeating units represented by the following general formula (1).
˜30 mol% and 95 to 70 mol% of the repeating unit represented by the following general formula (2).

[0019]

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[0020]

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However, in the general formula (1), R ¹ to
R ⁴ is a hydrogen atom or a methyl group. This methyl group has the effect of increasing the solubility without lowering the glass transition temperature. X is a cycloalkylene group having 5 to 10 carbon atoms, an araalkylene group having 7 to 15 carbon atoms, or a haloalkylene group having 1 to 5 carbon atoms.

More specifically, X is, as a cycloalkylene group, 1,1-cyclopentylene, 1,1-cyclohexylene, 1,1- (3,3,5-trimethyl) cyclohexylene, norbornane-2. , 2-diyl and the like, araalkylene groups include phenylmethylene, diphenylmethylene, 1,1- (1-phenyl) ethylene, 9,9.
-As a haloalkylene group such as fluorenylene, 2,
2-hexafluoropropylene, 2,2- (1,1,
3,3-Tetrafluoro-1,3-dichloro) propylene and the like are preferably used. These may be one kind or two or more kinds.

The polycarbonate obtained from the above-mentioned bisphenol has the effect of raising the glass transition temperature because of the rigidity derived from the ring structure.

As a result of these, as optical characteristics, the retardation value is 20 nm or less, the absolute value of the slow axis angle distribution is 15 ° or less, and the haze value is 0.8% or less. Is 0.10% or less even after heat treatment at 120 ° C for 1 hour, and at 30 ° C at 30 ° C.
Even after the heat treatment for a minute, it is possible to obtain the characteristic of being 0.15% or less.

The retardation is the product of the refractive index anisotropy Δn in the film plane and the film thickness d (nm) Δn ·
It is represented by d (nm). Usually, a polymer film has wavelength dependence of retardation, and it is preferable that the retardation value and the slow axis angle distribution are in the measurement wavelength of 400 nm to 800 nm. However, the value in the present invention depends on the value measured at 590 nm. Defined.

The retardation value and the slow axis angle distribution are measured by a known measuring technique such as a rotation analyzer method and a polarization modulation method. In this measurement, since a low retardation value is handled, the low retardation value is handled. It is preferable to select an accurate measurement method for the values. In this measurement, a multi-wavelength birefringence measuring device M-150 manufactured by JASCO Corporation, which uses the polarization modulation method as a measurement principle, was used.

The dimensional stability is 1 cm in width and 10 c in length.
m size film samples are cut in the film flow direction and width direction respectively, the length is precisely measured with an electronic micrometer, and the length is precisely measured by processing at a predetermined temperature and time. The difference in length was divided by the original length, and the value was expressed as% and defined as dimensional stability.

The above-mentioned non-bisphenol A in the present invention
The bisphenol component having a skeleton preferably has a perhydroisophorone skeleton or a fluorene skeleton. Particularly preferred monomer structures for forming the perhydroisophorone skeleton and the fluorene skeleton are shown in the following general formulas (3) and (4).

[0029]

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[0030]

[Chemical 4]

The polycarbonate copolymer having a perhydroisophorone skeleton is excellent in transparency because it has a smaller absorption coefficient in a short wavelength region than the polycarbonate copolymer having a fluorene skeleton particularly in optical characteristics. On the other hand, the polycarbonate copolymer having a fluorene skeleton is superior to the polycarbonate copolymer having a perhydroisophorone skeleton particularly in heat resistance. These choices are selected according to the required characteristics.

The optical compensation film substrate has an optical layer of polymer liquid crystal or the like formed on the substrate. Therefore, it is desired that the optical layer is not affected optically. That is, it is preferable that there is less anisotropy and that it is more transparent. That is, the retardation in the plane of the film is more preferably 15 nm or less. It is known that if the retardation in the film surface is 15 nm or less, it is below the limit that can be visually discriminated by humans. And even more preferably, the retardation value is 10 nm or less.

In addition, for example, when the optical axis of the optical layer such as a polymer liquid crystal is aligned with the slow axis of the substrate for the optical compensation film of the present invention at an appropriate angle, a higher optical property may be exhibited. In the case of using at least two or more optical compensation films in one liquid crystal display device, the direction of the slow axis of the substrate for the optical compensation film becomes a very important optical characteristic.

For example, when the optical compensation films using the two optical compensation film substrates are laminated so that the slow axes are parallel to each other, the influence of the two optical compensation film substrates on the optical characteristics is as follows. The result is to give the sum of retardations on each of the substrates. On the contrary, when the slow axis is made orthogonal, it is represented by the difference. That is, even if they have the same in-plane retardation, different results are given depending on the bonding angle with other optical elements.
That is, even if the retardation is the same, if the slow axes are locally different in the plane, the optical characteristics cannot be made uniform in the plane.

Further, since the substrate for the optical compensation film is usually cut into a suitable size according to the application, it is used.
In order to minimize the loss in cutting, it is preferable that the slow axes are more aligned within a certain range.

Such a slow axis angle distribution does not have to have the above-mentioned swing width around the film flow direction, but may have the above-mentioned swing width around a certain direction in the film plane.
This direction is usually determined by the tension applied to the film in the film forming process, particularly in the drying process. This is because the film is cut into an appropriate size and used in the subsequent step. In the slow axis angle distribution of ± 10 ° or more, even if the retardation is 15 nm or less, in-plane nonuniformity may be noticeable depending on the usage. Therefore, the slow axis angle distribution is more preferably ± 10 ° or less, and even more preferably the slow axis angle distribution is ± 7.5 nm or less.

The optical characteristics of the optical compensation film substrate are required to be transparent. Transparency is evaluated by the transmittance and the haze value. This haze value also expresses the scattering of light on the substrate for the optical compensation film.
However, multiple scattering due to impurities in the film cancels the polarized light. In particular, when it is used in a liquid crystal display device using a polarizing plate, the polarization characteristics are changed. Therefore, it is preferable to keep the haze value as low as possible. That is, the haze value is more preferably 0.6% or less.

The evaluation can be made by the transmittance, but in this case, the transmittance is preferably 85% or more, more preferably 90% or more in the measurement wavelength of 400 nm to 800 nm.

As a method for forming a film from polycarbonate, two methods, a melt extrusion method and a solution casting film forming method, are generally well known. The solution casting film formation method is inferior to the melt extrusion method in productivity. However, it is far superior to the melt-extrusion method in that it has few defects in the formed film. In addition, the defect here mainly refers to an abnormality such as a foreign substance that becomes a defect in appearance. For example, die lines, gelled products, fish eyes, and carbides can be said to be defects inherent in melt-extruded films, and it is desired that such defects be small for use as a substrate for an optical compensation film as in the present invention. Therefore, the polymer film in the optical compensation film substrate of the present invention is preferably formed by a solution casting method.

The solution casting method is a method in which a polymer is dissolved in a solvent and cast from a die onto a flat substrate to form a film.
Most polymers can be formed into a film if they are soluble in a solvent. Therefore, if the solution casting method is used, the average molecular weight of the polycarbonate copolymer is about 800
A resin of about 00 can be formed into a film. Increasing the average molecular weight raises the glass transition temperature and gives favorable results such as thermal durability. Further, in the manufacturing process, the melt extrusion method has a drawback that heat and tension act on the film to a large extent and the birefringence becomes large, but the solution casting method has a small influence and can suppress the birefringence to a low level. is there.

Factors that control the birefringence in the solution casting method include the characteristics of the die, the condition of the belt, the drying conditions, the film tension and the transport conditions, and the like. Since the resin can be used and the temperature condition is relatively mild, it is possible to manufacture a polymer film having excellent birefringence characteristics with good productivity.

Further, according to this method, even when additives such as an ultraviolet absorber and an antistatic agent are added to the film, if necessary, a material soluble in the film-forming solvent is selected and mixed in an appropriate amount. It is also possible to add a function to the film. In this case, the additive does not have to be one kind and may be two or more kinds.

When the above-mentioned polycarbonate copolymer is formed by solution film formation, the solvent used for film formation may remain in the film. The residual solvent plasticizes the film, resulting in a decrease in glass transition temperature and a decrease in mechanical properties. Therefore, it is preferable to completely remove the residual solvent, but from the viewpoint of productivity, the residual solvent amount is preferably 0.3% by weight or less.

As the solvent, known ones such as methylene chloride can be used. However, in this case, it is necessary to select a solvent in consideration of solution stability, film forming property and the like. The method of reducing the amount of residual solvent is mainly heat treatment, but in consideration of effects and economy, it is preferable to use a low boiling point solvent such as methylene chloride as the main solvent for solution casting.

As a method for measuring the residual solvent, a known method can be used. For example, a weight method in which a film is completely dried and a weight change is measured, and a nuclear magnetic resonance spectrum method (NMR) is used.
Method) etc.

If the glass transition temperature of the substrate for the optical compensation film is 150 ° C. or higher, the step of coating the optical layer such as polymer liquid crystal on the substrate in the optical compensation film manufacturing process,
And it can endure a heat treatment process etc. sufficiently. Furthermore, it can withstand the environment when used in a liquid crystal display device or the like.

In addition, the dimensional stability required in the optical compensation film manufacturing process is such that at the temperature of 100 ° C. or higher, the film is heat-shrinked uniformly in the machine direction and the width direction. The dimensional stability of the substrate is 120 ° C.
After heat treatment for 1 hour, the flow direction and width direction of the film are each 0.05% or less, and after heat treatment at 150 ° C. for 30 minutes, the flow direction and width direction of the film are both 0.
It is more preferably 1%. In order to uniformly obtain an optical layer having good characteristics on the substrate in the case of using a manufacturing process in which an optical layer is formed on the substrate for an optical compensation film by roll-to-roll by coating or transfer, etc., this condition is required. It becomes important.

Moisture resistance is not specified because the film is used by bonding it to other optical elements such as a polarizing plate, but after treatment for 1 hour in an environment of a temperature of 60 ° C. and a humidity of 90%, The dimensional change of the substrate preferably satisfies the above characteristics.

Further, the thickness of the above-mentioned polycarbonate copolymer film which is the substrate for the optical compensation film has a handling property in the process of manufacturing the optical compensation film and the step of laminating with another retardation plate, a polarizing plate or a liquid crystal cell,
Considering the size of the retardation, etc.
It is preferably 200 μm.

When the thickness is less than 50 μm, the tension of the film is lowered, which may cause difficulties in the optical compensation film manufacturing process and the subsequent laminating process with a polarizing plate or the like. If it is thicker than 200 μm, it becomes difficult to reduce optical properties such as retardation.
Further, the solvent drying step by the solution casting method may take a long time, which may reduce the productivity.

Further, since the unevenness of the thickness of the substrate affects the thickness of the optical layer such as polymer liquid crystal formed on the substrate,
It is preferable to minimize the thickness unevenness of the substrate. That is, the thickness unevenness is preferably within ± 5%. Even more preferably, it is within ± 2.5%. Further, it is not preferable that the unevenness of the film thickness locally and rapidly changes. The film thickness can be measured by an optical non-contact measurement method or a mechanical contact measurement method, but any method can be used as long as it can be accurately measured.

The properties of the polycarbonate copolymer films described thus far must be achieved not only on certain parts of the film, but on the entire surface of the film. Uniformity of the properties in the film flow direction and width direction is an important item for this application. When using it as a substrate for an optical compensation film, which is this application, it is necessary to cut it according to the size of the liquid crystal panel, and the uniformity in the film flow direction and width direction greatly affects productivity. Because.

Various optical layers can be formed on the substrate for the optical compensation film. For example, a polymer liquid crystal that is nematically aligned in a liquid crystal state may be formed on the substrate. Furthermore, an inorganic layered compound composed of a clay mineral may be dispersed on a nonionic hydrophilic resin such as polyvinyl alcohol to form it on the substrate.

When a solvent is used to form such an optical layer, if a solvent resistance is desired to be imparted to the polycarbonate copolymer film, a solvent resistant layer may be formed on at least one of the optical compensation film substrates. preferable. This solvent resistant layer can be formed by a known coating and curing method using a known material, for example, a material having a silicone resin-based crosslinked structure, an acrylic resin-based crosslinked structure, an epoxy resin-based crosslinked structure, or the like. Solvent resistance is intended to impart durability to solvents and other chemicals in the process of forming an optical layer on an optical compensation film substrate, and stability to organic chemicals such as methylene chloride, acetone and N-methylpyrrolidone. It is preferable to set materials and curing conditions that can sufficiently secure the above.

Further, when forming the above-mentioned optical layer and the like, it is preferable to provide an adhesive layer on at least one side of the substrate in order to improve the adhesiveness to the substrate. A known adhesive layer can be used as this adhesive layer, but this is appropriately selected depending on the material used for the optical layer. Further, in order to improve the adhesiveness, the surface property may be modified by chemicals, UV, ozone, plasma treatment or the like.

Further, in order to orient the optical layer, it is preferable to form an orientation film. This alignment film may be formed on the solvent resistant layer described above or may be formed directly on the substrate. This alignment film is formed by forming a known material such as polyimide or polyvinyl alcohol by a known method such as a spin coating method and performing a rubbing treatment or the like.

That is, in the substrate for an optical compensation film of the present invention, it is preferable that at least one surface of the polymer film is provided with a solvent resistant layer and / or an adhesive layer and / or an alignment film.

[0058]

Example 1 Bisphenol A and bisphenol having a perhydroisophorone skeleton were copolymerized by a phosgene method to obtain an aromatic polycarbonate resin having an average molecular weight of 35,000. The copolymerization ratio at that time was 15 mol% of bisphenol having a perhydroisophorone skeleton with respect to the bisphenol A component. The glass transition temperature of the obtained resin was 164 ° C.

20% by weight of this resin was dissolved in methylene chloride. This solution is die-coated,
It was cast on a polyester film having a thickness of 175 μm.
This was dried in a drying oven until the residual solvent was close to 14% by weight, and at that time, it was peeled from the polyester film. The peeled film was adjusted to 0.0% residual solvent in a drying oven at a temperature of 125 ° C. while keeping the vertical and horizontal tension balance.
Dry to 9%.

The thickness of the film thus obtained is 106.
The thickness unevenness in the width direction was ± 3 μm. The haze value of the film is 0.5 as measured by a haze meter.
%Met. The dimensional stability was 0.02% after heat treatment at 120 ° C. for 1 hour and 0.06% after heat treatment at 150 ° C. for 30 minutes. The retardation value in the measurement light of 590 nm was 7 ± 2 nm in the width direction, and the distribution of the slow axis based on the flow direction was ± 6 °.

A silicone resin was applied and dried on the film substrate using a reverse roll coater. Further, an alignment film made of polyimide was formed thereon, and a rubbing treatment was performed in the film flow direction.

Next, 7% by weight of a polyester type polymer liquid crystal which is a main chain type polymer liquid crystal was dissolved in phenol / tetrachloroethane (weight ratio 60/5). This solution
It was applied on the above-mentioned substrate with an alignment film. After application, 140
It heat-processed at 1 degreeC for 1 hour. It was then cooled to immobilize the uniform monodomain twisted nematic structure.

When the optical element thus obtained was measured by ellipsometry, the twist angle was 250 °. Further, a heat resistance test at 80 ° C. for 100 hours was carried out, and observation under a polarizing microscope and the like were carried out. As a result, it had a uniform monodomain twisted nematic structure and showed almost no change from the initial value.

[0064]

Example 2 Bisphenol A and bisphenol having a fluorene skeleton were copolymerized by the phosgene method to obtain an aromatic polycarbonate resin having an average molecular weight of 36000. The copolymerization ratio at that time was 1 for bisphenol having a fluorene skeleton with respect to bisphenol A component.
It was 6 mol%. The glass transition temperature of the obtained resin was 170 ° C.

20% by weight of this resin was dissolved in methylene chloride. This solution is die-coated,
It was cast on a polyester film having a thickness of 175 μm.
This was dried in a drying oven until the residual solvent was close to 12% by weight, at which point it was peeled from the polyester film. The peeled film was adjusted to 0.0% residual solvent in a drying oven at a temperature of 124 ° C. while balancing the vertical and horizontal tensions.
Dry to 6%.

The thickness of the film thus obtained is 99 μm.
The thickness unevenness in the width direction was ± 3 μm. The haze value of the film is 0.4% as measured by a haze meter.
Met. The dimensional stability was 0.03% after heat treatment at 120 ° C. for 1 hour and 0.07% after heat treatment at 150 ° C. for 30 minutes. The retardation value in the measurement light of 590 nm was 8 ± 2 nm in the width direction, and the distribution of the slow axis based on the flow direction was ± 7 °.

A silicone resin was applied and dried on the film substrate using a reverse roll coater. Further, an alignment film made of polyvinyl alcohol was formed thereon and rubbed in the film flow direction.

Next, 8% by weight of a polyester type polymer liquid crystal which is a main chain type polymer liquid crystal was dissolved in phenol / tetrachloroethane (weight ratio 60/12). This solution was applied onto the above-mentioned substrate with an alignment film. After application 1
It heat-processed at 50 degreeC for 1 hour. It was then cooled to immobilize the uniform monodomain twisted nematic structure.

The optical element thus obtained was measured by an ellipsometry at a measurement wavelength of 633 nm, and the retardation was 360 nm. Also, 80 ℃ 100
A heat resistance test was conducted for a period of time, and observation with a polarizing microscope was conducted. As a result, it had a uniform monodomain twisted nematic structure and showed almost no change from the initial value.

[0070]

Example 3 Bisphenol A and terephthalic acid were copolymerized to obtain an aromatic polyester carbonate resin having an average molecular weight of 33,000. The copolymerization ratio at that time was 23 mol% of the terephthalic acid component with respect to the bisphenol A component.
And The glass transition temperature of the obtained resin is 1
It was 66 ° C.

20% by weight of this resin was dissolved in methylene chloride. This solution is die-coated,
It was cast on a polyester film having a thickness of 175 μm.
This was dried in a drying oven until the residual solvent was close to 15% by weight, at which point it was peeled from the polyester film. The peeled film was adjusted to a residual solvent content of 0.0 in a drying oven at a temperature of 127 ° C. while maintaining a vertical and horizontal tension balance.
Dry to 5%.

The thickness of the film thus obtained is 109
The thickness unevenness in the width direction was ± 3 μm. The haze value of the film is 0.4 as measured by a haze meter.
%Met. The dimensional stability was 0.04% after heat treatment at 120 ° C. for 1 hour and 0.08% after heat treatment at 150 ° C. for 30 minutes. The retardation value in the measurement light of 590 nm was 6 ± 2 nm in the width direction, and the distribution of the slow axis based on the flow direction was ± 6 °.

A silicone resin was applied and dried on the film substrate using a reverse roll coater. Further, an alignment film made of polyimide was formed thereon, and a rubbing treatment was performed in the film flow direction.

Next, 9% by weight of a polyester type polymer liquid crystal which is a main chain type polymer liquid crystal was dissolved in phenol / tetrachloroethane (weight ratio 60/10). This solution was applied onto the above-mentioned substrate with an alignment film. After application 1
It heat-processed at 50 degreeC for 1 hour. It was then cooled to immobilize the uniform monodomain twisted nematic structure.

When the optical element thus obtained was measured by ellipsometry, the twist angle was 260 °. Further, a heat resistance test at 80 ° C. for 100 hours was carried out, and observation under a polarizing microscope and the like were carried out. As a result, it had a uniform monodomain twisted nematic structure and showed almost no change from the initial value.

[0076]

Example 4 Bisphenol A and isophthalic acid were copolymerized to obtain an aromatic polyester carbonate resin having an average molecular weight of 36000. The copolymerization ratio at that time was 20 mol% of the isophthalic acid component with respect to the bisphenol A component.
And The glass transition temperature of the obtained resin is 1
It was 68 ° C.

20% by weight of this resin was dissolved in methylene chloride. This solution is die-coated,
It was cast on a polyester film having a thickness of 175 μm.
This was dried in a drying oven until the residual solvent was close to 14% by weight, at which point it was peeled from the polyester film. The peeled film was treated with a residual solvent of 0.0% in a drying oven at a temperature of 128 ° C. while balancing the vertical and horizontal tensions.
Dry to 4%.

The thickness of the film thus obtained is 101.
The thickness unevenness in the width direction was ± 3 μm. The haze value of the film is 0.3 as measured by a haze meter.
%Met. The dimensional stability was 0.03% after heat treatment at 120 ° C. for 1 hour and 0.07% after heat treatment at 150 ° C. for 30 minutes. The retardation value in the measurement light of 590 nm was 7 ± 2 nm in the width direction, and the distribution of the slow axis based on the flow direction was ± 8 °.

A silicone resin was applied and dried on the film substrate using a reverse roll coater. Further, an alignment film made of polyimide was formed thereon, and a rubbing treatment was performed in the film flow direction.

Next, a polyester type polymer liquid crystal as a main chain type polymer liquid crystal was dissolved in 9% by weight in phenol / tetrachloroethane (weight ratio 60/11). This solution was applied onto the above-mentioned substrate with an alignment film. After application 1
It heat-processed at 50 degreeC for 1 hour. It was then cooled to immobilize the uniform monodomain twisted nematic structure.

When the optical element thus obtained was measured by ellipsometry, the twist angle was 245 °. Further, a heat resistance test at 80 ° C. for 100 hours was carried out, and observation under a polarizing microscope and the like were carried out. As a result, it had a uniform monodomain twisted nematic structure and showed almost no change from the initial value.

[0082]

Example 5 A bisphenol having a perhydroisophorone skeleton, terephthalic acid, and bisphenol A were copolymerized to obtain an aromatic polyester carbonate resin having an average molecular weight of 38,000. The copolymerization ratio at that time was 5: 5: 90 (mol%), respectively. The glass transition temperature of the obtained resin was 166 ° C.

20% by weight of this resin was dissolved in methylene chloride. This solution is die-coated,
It was cast on a polyester film having a thickness of 175 μm.
This was dried in a drying oven until the residual solvent was close to 17% by weight, at which point it was peeled from the polyester film. The peeled film was adjusted to 0.0% residual solvent in a drying oven at a temperature of 129 ° C. while maintaining a vertical and horizontal tension balance.
Dry to 4%.

The thickness of the film thus obtained is 107.
The thickness unevenness in the width direction was ± 3 μm. The haze value of the film is 0.3 as measured by a haze meter.
%Met. The dimensional stability was 0.03% after the heat treatment at 120 ° C. for 1 hour and 0.08% after the heat treatment at 150 ° C. for 30 minutes. The retardation value in the measurement light of 590 nm was 5 ± 2 nm in the width direction, and the distribution of the slow axis based on the flow direction was ± 8 °.

A silicon resin was applied and dried on the film substrate using a reverse roll coater. Further, an alignment film made of polyimide was formed thereon, and a rubbing treatment was performed in the film flow direction.

Next, a polyester type polymer liquid crystal which is a main chain type polymer liquid crystal was dissolved in 10% by weight in phenol / tetrachloroethane (weight ratio 60/10). This solution was applied onto the above-mentioned substrate with an alignment film. After application 1
It heat-processed at 50 degreeC for 1 hour. It was then cooled to immobilize the uniform monodomain twisted nematic structure.

When the optical element thus obtained was measured by ellipsometry, the twist angle was 265 °. Further, a heat resistance test at 80 ° C. for 100 hours was carried out, and observation under a polarizing microscope and the like were carried out. As a result, it had a uniform monodomain twisted nematic structure and showed almost no change from the initial value.

[0088]

Example 6 Bisphenol having a fluorene skeleton,
By copolymerizing isophthalic acid and bisphenol A, an aromatic polyester carbonate resin having an average molecular weight of 39000 was obtained. The copolymerization ratio in that case is 7: respectively.
It was set to 5:88 (mol%). The glass transition temperature of the obtained resin was 168 ° C.

20% by weight of this resin was dissolved in methylene chloride. This solution is die-coated,
It was cast on a polyester film having a thickness of 175 μm.
This was dried in a drying oven until the residual solvent was close to 17% by weight, at which point it was peeled from the polyester film. The peeled film was adjusted to 0.0% residual solvent in a drying oven at a temperature of 130 ° C. while balancing the vertical and horizontal tensions.
Dry to 4%.

The thickness of the film thus obtained is 104.
The thickness unevenness in the width direction was ± 4 μm. The haze value of the film is 0.4 as measured by a haze meter.
%Met. The dimensional stability was 0.02% after heat treatment at 120 ° C. for 1 hour and 0.08% after heat treatment at 150 ° C. for 30 minutes. The retardation value in the measurement light of 590 nm was 6 ± 2 nm in the width direction, and the distribution of the slow axis based on the flow direction was ± 7 °.

A silicone resin was applied and dried on the film substrate using a reverse roll coater. Further, an alignment film made of polyimide was formed thereon, and a rubbing treatment was performed in the film flow direction.

Next, a polyester type polymer liquid crystal which is a main chain type polymer liquid crystal was dissolved in 10% by weight with respect to phenol / tetrachloroethane (weight ratio 50/10). This solution was applied onto the above-mentioned substrate with an alignment film. After application 1
It heat-processed at 50 degreeC for 1 hour. It was then cooled to immobilize the uniform monodomain twisted nematic structure.

When the optical element thus obtained was measured by ellipsometry, the twist angle was 275 °. Further, a heat resistance test at 80 ° C. for 100 hours was carried out, and observation under a polarizing microscope and the like were carried out. As a result, it had a uniform monodomain twisted nematic structure and showed almost no change from the initial value.

[0094]

[Comparative Example 1] A polycarbonate resin having a thickness of 125 µm was formed from a polycarbonate resin made of bisphenol A (average molecular weight 24000) by a melt extrusion method.

The retardation value of such a film measured with measuring light of 590 nm is about 3 as an average value in the width direction.
0 nm, and the slow axis distribution based on the flow direction is ±
It was 20 °. This film was placed under crossed Nicols, and the film flow direction was observed. It was visually observed that light leaked at some places.

Further, an attempt was made to perform the same processing as in Example 1 on such a film. However, when heat-treated at 140 ° C. after application of the polymer liquid crystal, the substrate film contracted and wavy, which made it difficult to form a uniform monodomain twisted nematic structure.

[0097]

INDUSTRIAL APPLICABILITY The present invention uses a polycarbonate film having a specified physical property value and a specified copolymerization composition as a substrate for an optical compensation film in an optical compensation film exhibiting an excellent optical compensation effect in a liquid crystal display device. As a result, there is an effect that it is possible to provide an optical compensation film having very good characteristics and excellent economical efficiency. That is, as the optical characteristics, the retardation value is 20 nm or less, the absolute value of the slow axis angle distribution is 15 ° or less, and the haze value is 0.8% or less, while the dimensional stability is 120 ° C. It is possible to obtain a substrate for an optical compensation film having the characteristics that it is 0.10% or less even after heat treatment for 1 hour and 0.15% or less even after heat treatment at 150 ° C. for 30 minutes.

Claims (11)

[Claims] 1. A copolymerization ratio of a bisphenol component consisting of a non-bisphenol A skeleton to bisphenol A is 5
A bisphenol A copolymerized with 30 mol% to 30 mol%, an in-plane optically isotropic polymer film made of an aromatic polycarbonate having an average molecular weight of 30,000 or more and a glass transition temperature of 150 ° C. or more as a substrate. A substrate for an optical compensation film, which is used as a substrate in an optical compensation film having an optical layer having an optical compensation function formed thereon. 2. The substrate for an optical compensation film according to claim 1, wherein the bisphenol component having a non-bisphenol A skeleton has a perhydroisophorone skeleton. 3. The substrate for an optical compensation film according to claim 1, wherein the bisphenol component having a non-bisphenol A skeleton has a fluorene skeleton. 4. A copolymer of bisphenol A obtained by copolymerizing terephthalic acid, isophthalic acid or a mixture thereof with bisphenol A at a copolymerization ratio of 5 to 45 mol%, having an average molecular weight of 30,000 or more and a glass transition. An in-plane optically isotropic polymer film made of an aromatic polyester carbonate having a point temperature of 150 ° C. or higher is used as a substrate in an optical compensation film formed by forming an optical layer having an optical compensation function on the substrate. Substrate for optical compensation film. 5. A copolymer of bisphenol A obtained by copolymerizing a bisphenol component having a perhydroisophorone skeleton or a fluorene skeleton and terephthalic acid, isophthalic acid or a mixture thereof with a bisphenol A copolymerization ratio of 5 to 30 mol%. A substrate for an optical compensation film, comprising a polymer film of an aromatic polyester carbonate having an average molecular weight of 30,000 or more and a glass transition temperature of 150 ° C. or more made of a polymer as a substrate. 6. The polymer film used as the substrate is
The retardation value is 15 nm or less, the slow axis angle distribution is ± 10 ° or less, and the haze value is 0.6% or less, and the substrate for an optical compensation film according to any one of claims 1 to 5. . 7. The polymer film used as the substrate is
The film is formed by a solution casting method.
The substrate for an optical compensation film according to any one of 1. 8. The polymer film used as the substrate is
The optical compensation film substrate according to claim 1, wherein the residual solvent concentration is 0.3% by weight or less. 9. The polymer film used as the substrate is
After heat treatment at 120 ° C. for 1 hour, the dimensional stability of the film is 0.05% or less in each of the flow direction and the width direction, and 15
The substrate for optical compensation film according to any one of claims 1 to 8, which has a dimensional stability of 0.1% or less in each of a flow direction and a width direction of the film after heat treatment at 0 ° C for 30 minutes. . 10. The polymer film used as a substrate has a thickness of 50 to 200 μm and a thickness unevenness of ± 5%.
It is within the limits, The board | substrate for optical compensation films in any one of Claims 1-9 characterized by the above-mentioned. 11. The polymer film used as a substrate is provided with a solvent resistant layer and / or an adhesive layer and / or an alignment film on at least one surface thereof. Substrate for optical compensation film.