JP2011180553A - Multilayer optical compensated film and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer optical compensated film that enhances the optical compensation performance by controlling the refractive index anisotropy. <P>SOLUTION: The multilayer optical compensated film 1 includes a base film 2, and an optical anisotropy layer 3, laminated at least on one side of the base film 2. The optical anisotropic layer 3 is formed of an aqueous solution or aqueous dispersion containing water soluble resin having lyotropic liquid crystal properties and an anionic surface activity compound constituting at least two sulfonate groups. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is an optical compensation laminated film having optical compensation performance, and is used in, for example, a liquid crystal display device and the like, and an optical compensation laminated film capable of improving the display image of the liquid crystal display device, and the optical The present invention relates to a method for producing a compensation laminated film.

  A liquid crystal display (LCD) is configured by adhering an optical film and a polarizing plate to a liquid crystal cell in which liquid crystal molecules are enclosed and electrodes are incorporated. As an operation method of the liquid crystal display device, there are a TN (Twisted Nematic) mode, an STN (Super Twisted Nematic) mode, a VA (Vertical Alignment) mode, an IPS (In-Plane Switching) mode, an OCB (Optically Compensated Bend, etc.). Various schemes mainly defined by the alignment form of liquid crystal molecules have been proposed. Each of these displays an image using the electro-optical characteristics of liquid crystal molecules.

  In the liquid crystal display device, optical films having various functions are used for the purpose of improving the image quality of the display viewed through the polarizing plate. The optical film needs to have various optical characteristics depending on applications, including transparency and optical compensation. In particular, optical anisotropy is applied as the above optical film in order to eliminate the optical distortion caused by the birefringence inherent in liquid crystals and the viewing angle dependency such as the coloration of the display depending on the visual direction. Compensation films are widely used.

  In large screen applications such as liquid crystal televisions and monitors, VA (vertical alignment) liquid crystal display devices tend to become mainstream because they are excellent in wide viewing angles and high contrast ratios. A VA liquid crystal display device has a structure in which liquid crystals are vertically aligned. For this reason, in order to compensate for the light that has passed through the liquid crystal layer, it is desirable that the refractive index ellipsoid is vertically short. Further, for the optical compensation film used in the VA liquid crystal display device, it is desirable that the refractive index ellipsoid has a long axis in the horizontal direction of the panel, is flat and has a positive intrinsic birefringence. The NZ coefficient of the optical compensation film is desirably 1.0 or more, and more desirably 1.3 or more.

  An IPS (horizontal electric field) liquid crystal display device displays an image by controlling the transmitted light by changing the orientation of liquid crystal molecules in a horizontal plane parallel to the panel substrate. An IPS liquid crystal display device has a wide viewing angle and a small change in color tone on the principle of operation. For this reason, IPS liquid crystal display devices are widely used for liquid crystal televisions, mobile terminal monitors, and the like. In the OCB type liquid crystal display device, liquid crystal molecules are aligned so as to be inclined with respect to the panel substrate, thereby controlling image display. In the IPS mode or OCB mode liquid crystal display device, the liquid crystal molecules are aligned so as to be horizontal or inclined with respect to the panel substrate. Therefore, the NZ coefficient of the optical compensation film is desirably 1.0 or less.

  In order to develop optical anisotropy and the like in the optical compensation film, a method of stretching the film by a heat stretching method and controlling the orientation of resin molecules is known.

  However, the heat stretching method cannot stretch the film uniformly over the entire width of the film. In addition, it is difficult to produce a large optical compensation film for use in a large liquid crystal display device, which is in great demand in recent years, by the heat stretching method.

  Further, as an example of the optical compensation film, in Patent Document 1 below, a homeotropic alignment side chain type liquid crystal polymer is applied on a substrate, and then the polymer is homeotropically aligned in a liquid crystal state. An optical compensation film obtained by fixing in a state where the state is maintained is disclosed.

  Patent Document 2 below discloses a solution containing a liquid crystal molecule having a nematic phase in the liquid crystal state and in a glass state at a temperature lower than the glass transition in order to control the alignment state of the liquid crystal molecules, Using a substrate having a regulating force, the liquid crystal molecules are aligned in the first direction by the orientation regulating force of the substrate, and an angle of 45 to 90 ° is formed with respect to the first direction by applying a magnetic field. An optical compensation film in which liquid crystal molecules are aligned in the direction 2 is disclosed.

  Patent Document 3 below discloses an optical compensation film in which a film layer formed using a liquid crystal material in which a liquid crystal compound is dissolved in an organic solvent is formed on a support such as a plastic film. .

JP 2003-149441 A JP 2007-55193 A JP 2007-152173 A

  In Patent Documents 1 to 3, the reproducibility of alignment control of liquid crystal molecules is insufficient, and the optical anisotropy of the optical compensation film is not always stable. In particular, the alignment pattern in the thickness direction often does not take a predetermined form, and biaxiality may become unstable.

  In addition, the selection of the solvent in the liquid crystal material is important. The solvent affects the alignment control of the liquid crystal molecules and the strength and uniformity of the coating film. As described in Patent Document 3, organic solvents are widely used as solvents for liquid crystal materials. A liquid crystal material containing an organic solvent has high wettability, and has a relatively good affinity with a substrate film to which the liquid crystal material is applied. For this reason, if a liquid crystal material containing an organic solvent is used, a uniform coating film can be easily obtained. However, it is desirable not to use an organic solvent as much as possible because of the demands of low pollution, resource saving and cost reduction, and the problem of the manufacturing environment.

  An object of the present invention is to provide an optical compensation laminated film capable of increasing the optical compensation performance by controlling the refractive index anisotropy, and a method for producing the optical compensation laminated film.

  A limited object of the present invention is an optical compensation laminated film having good front retardation and biaxiality and capable of improving the image display of a liquid crystal display device, and the production of the optical compensation laminated film Is to provide a method.

  According to a wide aspect of the present invention, it comprises a base film and an optical anisotropic layer laminated on at least one side of the base film, and the optical anisotropic layer has a water-soluble resin having lyotropic liquid crystal properties, There is provided an optical compensation laminated film formed of an aqueous solution or an aqueous dispersion containing an anionic surfactant compound having two or more sulfonic acid groups.

  In a specific aspect of the optical compensation laminated film according to the present invention, the water-soluble resin is an aromatic polyamide resin.

  In another specific aspect of the optical compensation laminated film according to the present invention, the surface active compound is a polycyclic phenyl compound.

  In still another specific aspect of the optical compensation laminated film according to the present invention, the refractive index anisotropy of the surface active compound satisfies the following formula (1), and is defined as a front retardation R0 defined by the following formula (2). (Nm) is in the range of 50 to 500 nm, and the NZ coefficient defined by the following formula (3) is in the range of 0.0 to 5.0.

nx = ny> nz (1)
In the above formula (1), nx represents the maximum refractive index of the surface active compound, ny represents the refractive index in the direction orthogonal to the nx direction in the surface of the surface active compound, and nz is orthogonal to the nx direction and the ny direction. Refractive index in the direction of

R0 (nm) = | nx−ny | × d (2)
In the above formula (2), nx represents the maximum refractive index in the optical compensation laminated film surface, ny represents the refractive index in the direction perpendicular to the nx direction in the optical compensation laminated film surface, and d represents the optical compensation laminated film. Represents the average thickness (nm).

Nz coefficient = (nx−nz) / (nx−ny) (3)
In the above formula (3), nx represents the maximum refractive index in the optical compensation laminated film surface, ny represents the refractive index in the direction orthogonal to the nx direction in the optical compensation laminated film surface, and nz represents the nx direction and the ny direction. Represents the refractive index in the direction orthogonal to

  In the method for producing an optical compensation laminated film according to the present invention, an aqueous solution or an aqueous dispersion containing a water-soluble resin having lyotropic liquid crystallinity and an anionic surfactant compound having two or more sulfonic acid groups is used. The aqueous solution or the aqueous dispersion is applied to at least one surface of the material film at a coating speed of 100 mm / second or more to form an optically anisotropic layer.

  The optical compensation laminated film according to the present invention includes a water-soluble resin in which an optical anisotropic layer laminated on at least one surface of a base film has lyotropic liquid crystal properties, and an anionic surfactant compound having two or more sulfonic acid groups. Therefore, the refractive index anisotropy can be controlled, and the optical compensation performance can be enhanced.

  In the method for producing an optical compensation laminated film according to the present invention, an aqueous solution containing a water-soluble resin having lyotropic liquid crystal properties and an anionic surfactant compound having two or more sulfonic acid groups on at least one surface of a base film or Since the optically anisotropic layer is formed by coating the aqueous dispersion at a coating speed of 100 mm / second or more, an optical compensation laminated film having high optical compensation performance can be obtained by controlling the refractive index anisotropy. .

FIG. 1 is a cross-sectional view showing an optical compensation laminated film according to an embodiment of the present invention.

  Hereinafter, the present invention will be clarified by describing specific embodiments and examples of the present invention with reference to the drawings.

  In FIG. 1, the optical compensation laminated | multilayer film which concerns on one Embodiment of this invention is shown with sectional drawing.

  An optical compensation laminated film 1 shown in FIG. 1 includes a base film 2 and an optical anisotropic layer 3 laminated on the first surface 2 a of the base film 2. The optical anisotropic layer 3 is not laminated on the second surface 2 b opposite to the first surface 2 a of the base film 2. The optical anisotropic layer should just be laminated | stacked on the at least single side | surface of the base film 2, and the optical anisotropic layer 3 may be laminated | stacked also on the 2nd surface 2b.

  In this embodiment, the optically anisotropic layer 3 is formed using an aqueous solution or an aqueous dispersion containing a water-soluble resin having lyotropic liquid crystallinity and an anionic surfactant compound having two or more sulfonic acid groups. Yes. Specifically, for example, the first surface 2a of the base film 2 is coated with the above aqueous solution or aqueous dispersion, and then dried to remove water to form an optically anisotropic layer. .

  The main feature of the present invention is that the optically anisotropic layer is formed using an aqueous solution or aqueous dispersion containing a water-soluble resin having lyotropic liquid crystallinity and an anionic surfactant compound having two or more sulfonic acid groups. There is in being.

  The present inventor has identified a material constituting an optical anisotropic layer having a plurality of different optical anisotropies and formed of a water-soluble resin as means for controlling front retardation and biaxiality as optical compensation performance. In order to further improve the wettability of the constituent material, a surface active action is imparted to at least one of the constituent materials of the optical anisotropic layer, thereby improving the uniformity of the optical anisotropic layer. It was found that the optical compensation performance can be accurately controlled. By using an aqueous solution or aqueous dispersion having the above specific composition, the refractive index anisotropy can be controlled and the optical compensation performance can be improved. For example, the front retardation R0 and the NZ coefficient of the optical compensation laminated film can be improved.

  By using the optical compensation laminated film according to the present invention, the display image of the liquid crystal display device can be improved.

  Furthermore, the present inventor applied the aqueous solution or aqueous dispersion at a coating speed of 100 mm / second or more to form an optically anisotropic layer, thereby reducing coating film unevenness and making the optical system more uniform. It has been found that an anisotropic layer can be formed.

  In the optical compensation laminated film according to the present invention, the optically anisotropic layer is formed of an aqueous solution or aqueous dispersion containing a water-soluble resin having lyotropic liquid crystallinity and an anionic surfactant compound having two or more sulfonic acid groups. Has been. The aqueous solution or aqueous dispersion contains water as a solvent.

(Water-soluble resin)
In the present invention, a water-soluble resin having lyotropic liquid crystallinity is used. The water-soluble resin is water-soluble and has a property of being soluble in water. If it has such a property, the said water-soluble resin will not be specifically limited. As for the said water-soluble resin, only 1 type may be used and 2 or more types may be used together.

  The water-soluble resin can be coated on the base film in a state dissolved or dispersed in water. In addition, when water is used, the cost is lower than when an organic solvent is used, and it is particularly excellent in terms of occupational health and work. In addition, the use of the water-soluble resin facilitates the preparation of an aqueous solution or aqueous dispersion, increases the coating properties of the aqueous solution or aqueous dispersion on the surface of the substrate, and increases the productivity of the optical compensation laminated film. In particular, the sanitary aspect and the maintenance aspect are particularly improved. The aqueous solution or aqueous dispersion preferably does not contain an organic solvent. However, the aqueous solution or aqueous dispersion may contain an organic solvent. For example, a small amount of organic solvent contained in the raw material may be included. By using water instead of organic solvent as the main solvent, the residual amount of organic solvent can be reduced in the coating film where water is volatilized after coating an aqueous solution or aqueous dispersion, and the commercial value of the resulting optical compensation laminated film Can be high.

  The water-soluble resin has lyotropic liquid crystallinity. When the water-soluble resin has lyotropic liquid crystallinity, liquid crystal molecules can be aligned by shearing during application of the aqueous solution or aqueous dispersion onto the base film.

  In general, in order to apply a liquid crystal material on a substrate film and align liquid crystal molecules, a substrate film having an alignment film is usually used. The optical axis determined by the alignment direction is controlled by aligning liquid crystal molecules in a specific direction by the alignment film using the substrate film having the alignment film. However, in this case, it is necessary to form an alignment film, which is not economical.

  Further, when forming the alignment film, an undercoat layer made of polyimide or polyvinyl alcohol is formed on the surface of the base film, and a rubbing roll in which fiber bundles are radially attached to the undercoat layer is brought into contact with the surface of the base material. Then, a rubbing process for polishing may be performed. As a result, fine scratches are shaped in a specific direction. This fine scratch serves as an alignment starting point for liquid crystal molecules. In addition, in order to form alignment film, the surface of a base film may be directly rubbed.

  However, when such rubbing treatment is performed, fragments are often generated on the base film after the rubbing treatment. The generated debris remains in the optical compensation laminated film as a foreign substance and becomes an optical defect in the obtained optical compensation laminated film. For this reason, if a rubbing process is performed, the product value of an optical compensation laminated film will fall.

  Therefore, it is preferable that the base film does not have an alignment film. Furthermore, it is preferable that the base film is not rubbed. By using the above aqueous solution or aqueous dispersion having a specific composition, the optical compensation of the optically compensated laminated film, whether it is a base film having no alignment film or a base film not further rubbed, Performance can be increased.

  When the liquid crystal expression temperature is lower than 80 ° C., when applied to a liquid crystal display, the alignment state of the liquid crystalline polymer cannot be maintained depending on the use environment of the liquid crystal display, and the optical compensation performance may be lost. is there. If the liquid crystal expression temperature is too high, deformation or alteration may occur depending on the material of the substrate film, and the value as an optical compensation laminated film may be significantly impaired.

  The water-soluble resin is a polymer having a liquid crystallinity structure in the main chain (main chain polymer liquid crystal compound) or a polymer having a liquid crystal structure in the side chain (side chain polymer liquid crystal compound). Preferably there is. As for the said water-soluble resin, only 1 type may be used and 2 or more types may be used together.

  Examples of the main chain type polymer liquid crystal compound include polyamide, polyester, polycarbonate, polyimide, polyurethane, polybenzimidazole, polybenzoxazole, polybenzthiazole, polyazomethine, and polyesteramide. , Polymer liquid crystal compounds such as polyester carbonate type and polyester imide type, and mixtures thereof.

  Examples of the side-chain polymer liquid crystal compound include a skeleton having a linear or cyclic structure such as polyacrylate, polymethacrylate, polyvinyl, polysiloxane, polyether, polymalonate, and polyester. Examples thereof include a polymer liquid crystal compound having a mesogen group bonded as a chain, and a mixture thereof.

The water-soluble resin is preferably an aromatic polyamide resin. The aromatic polyamide resin is a polyamide resin having an aromatic ring group. The aromatic polyamide resin is preferably an aromatic polyamide resin having a structural unit represented by the following formula (11).

  In the above formula (11), R1 represents an aromatic ring group, R2 represents an aliphatic group, an alicyclic group, an aromatic ring group, or a heterocyclic group, and n represents a natural number.

  The above-mentioned aromatic polyamide resin, in particular, the polyamide resin having an aromatic ring group represented by the above formula (11) has a high melting point and glass transition temperature compared to general-purpose resins, and is excellent in heat resistance. Have Since the aromatic polyamide resin has an aromatic ring and an amide bond, it is excellent in rigidity, toughness and chemical resistance, and exhibits high adhesiveness. These resin characteristics act particularly advantageously in the optical compensation laminated film. When an optical compensation laminated film using the above aromatic polyamide resin is incorporated into a liquid crystal display device, stable optical compensation performance is exhibited and a display image can be maintained at a high quality. In particular, even if the panel is exposed to high temperature due to backlight or the like in the panel, the retardation value is difficult to change. Further, since the optical anisotropic layer is rigid and tough, the optical anisotropic layer is difficult to peel from the base film, and the optical anisotropic layer is not easily chipped. For this reason, the value of the optical compensation laminated film can be increased.

  The aromatic polyamide resin can be obtained, for example, by polycondensing an aromatic dicarboxylic acid or an ester-forming derivative thereof and an aromatic, alicyclic or aliphatic diamine compound.

  The aromatic dicarboxylic acid or its ester-forming derivative is not particularly limited. Examples of the aromatic dicarboxylic acid or ester-forming derivative thereof include terephthalic acid, isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, paraphenylene dicarboxylic acid, dimethyl terephthalate, dimethyl isophthalate, dimethyl orthophthalate, and dimethyl naphthalene dicarboxylate. , Aromatic dicarboxylic acid such as dimethyl paraphenylene dicarboxylate, terephthalic acid dichloride, isophthalic acid dichloride, orthophthalic acid dichloride, naphthalene dicarboxylic acid dichloride and paraphenylene dicarboxylic acid dichloride, and modified products thereof. It is done. As for the said aromatic dicarboxylic acid or its ester-forming derivative, only 1 type may be used and 2 or more types may be used together.

The aromatic dicarboxylic acid or ester-forming derivative thereof preferably has at least one sulfonic acid group represented by the following formula (12). The water solubility of the aromatic polyamide resin can be further enhanced by the sulfonic acid group represented by the following formula (12).

  In said formula (12), M represents a hydrogen ion, a metal ion, an ammonium ion, or its derivative (s).

  Examples of the aromatic dicarboxylic acid having at least one sulfonic acid group represented by the above formula (12) or an ester-forming derivative thereof include a sulfonic acid group in the molecule of the aromatic dicarboxylic acid or the ester-forming derivative described above. Examples thereof include sulfonated derivatives obtained by introduction. The sulfonic acid group is preferably introduced into the aromatic nucleus, and the aromatic group preferably has a sulfonic acid group.

  The diamine compound is not particularly limited. Examples of the diamine compound include paraphenylenediamine, metaphenylenediamine, orthophenylenediamine, benzidine, tolidine, biphenyldiamine, fluorenediamine, methylenebisaniline, ethylenediamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, and undecadium. Examples include methylene diamine and derivatives thereof. The diamine compound may be an aromatic diamine compound or an aliphatic diamine compound. As for the said diamine compound, only 1 type may be used and 2 or more types may be used together.

  The diamine compound preferably has at least one sulfonic acid group represented by the formula (12). The water solubility of the aromatic polyamide resin can be further enhanced by the sulfonic acid group represented by the formula (12).

(Anionic surfactant compound)
In the present invention, an anionic surfactant compound having two or more sulfonic acid groups is used. As for the said surface active compound, only 1 type may be used and 2 or more types may be used together.

  In order to form the optically anisotropic layer, when an aqueous solution or water dispersion using water as a solvent is coated on the base film, water has low wettability because it has a lower surface tension than an organic solvent. It becomes relatively low and the coating film tends to be non-uniform. For this reason, the transparency of the obtained optical compensation laminated film may be lowered, or the appearance may be locally deteriorated. In particular, when an aromatic polyamide resin is used, the aromatic polyamide resin has a high viscosity and does not have sufficient fluidity to obtain a uniform coating film. Defects are particularly likely.

  Moreover, in order to improve the wettability, it is difficult to sufficiently increase the wettability only by using a compound having a general hydrophilic group and having a surface activity.

  In contrast, in the present invention, since an anionic surfactant compound having two or more sulfonic acid groups is used, the wettability of the aqueous solution or aqueous dispersion containing the water-soluble resin can be effectively increased. it can. When the water-soluble resin is an aromatic polyamide resin, the wettability can be remarkably increased by using the surfactant compound. When the wettability of the aqueous solution or aqueous dispersion with respect to the base film is increased, appearance defects are less likely to occur in the resulting optical compensation laminated film, and the front retardation and biaxiality of the optical compensation laminated film can be improved. .

  The refractive index anisotropy of the anionic surfactant compound preferably satisfies the following formula (1). The anionic surfactant compound preferably has a refractive index balance called negative C.

nx = ny> nz (1)
In the above formula (1), nx represents the maximum refractive index of the surface active compound, ny represents the refractive index in the direction orthogonal to the nx direction in the surface of the surface active compound, and nz is orthogonal to the nx direction and the ny direction. Refractive index in the direction of

  When the refractive index anisotropy of the anionic surfactant compound satisfies the above formula (1), the front retardation R0 becomes small, while the thickness retardation Rth defined by the following formula (5) is constant. The value of will be shown. Therefore, an optical anisotropic layer formed of an aqueous solution or an aqueous dispersion containing the water-soluble resin and the anionic surfactant compound can exhibit various optical compensation performances. For this reason, it is possible to design various refractive index anisotropy balances corresponding to methods such as the VA method, IPS method, OCB method and the like, in particular, methods that generate optical anisotropy in the thickness direction. Refractive index anisotropy in a wide range by using a water-soluble resin having a refractive index anisotropy such as the aromatic polyamide resin and an anionic surfactant compound having a refractive index anisotropy satisfying the above formula (1). The optical compensation performance can be further improved.

Rth (nm) = ((nx + ny) / 2−nz) × d (5)
In the above formula (5), nx represents the maximum refractive index in the optical compensation laminated film surface, ny represents the refractive index in the direction orthogonal to the nx direction in the optical compensation laminated film surface, and nz represents the nx direction and the ny direction. Represents the refractive index in the direction perpendicular to, and d represents the average thickness (nm) of the optical compensation laminated film.

  The refractive index of the anionic surfactant compound can be evaluated as follows, for example.

  First, the intrinsic refractive index is measured using an Abbe refractometer (manufactured by Atago Co., Ltd., model number “IT”). Next, using an automatic birefringence measurement apparatus (manufactured by Oji Scientific Instruments, model number “KOBRA-WR”), the refractive index in three directions orthogonal to each other with the wavelength of the measurement light set to 550 nm from the measured intrinsic refractive index value. nx, ny and nz are measured.

  The anionic surfactant compound is preferably a polycyclic compound, preferably a polycyclic aromatic compound, and preferably a polycyclic phenyl compound. The polycyclic phenyl compound also includes a compound having a phenylene group. The polycyclic compound preferably has two or more aromatic rings or heterocyclic rings. The polycyclic compound preferably has two or more aromatic groups, more preferably has two or more phenyl groups or phenylene groups, and more preferably has two or more phenylene groups. By using these preferable surface active compounds, the refractive index anisotropy satisfies the above formula (1), the refractive index anisotropy can be controlled in a wide range, and the optical compensation performance can be further enhanced.

  The polycyclic compound is preferably a polycyclic compound represented by the following formula (21).

_{M1O 3 S- (X) n -SO} 3 M2 ··· formula (21)
In said formula (21), X represents an aromatic ring group, a heterocyclic group, or these derivative groups, M1 and M2 represent a hydrogen ion, a metal ion, an ammonium ion, or its derivative, respectively, and n shows a natural number. In the above formula (21), X is preferably an aromatic ring group, and more preferably a phenylene group.

  In the polycyclic compound represented by the above formula (21), a hydrophilic sulfonic acid group is introduced into an aromatic ring group, a heterocyclic group or a derivative group thereof having high hydrophobicity. For this reason, the surface activity of the polycyclic compound represented by the above formula (21) is extremely high. When an aqueous solution or aqueous dispersion containing a polycyclic compound such as the above polycyclic phenyl compound is applied on a base film, the main surface of the base film and the aromatic ring surface are generally aligned in parallel (so-called plane orientation). The refractive index balance is such that the refractive index in the thickness direction of the obtained optical compensation laminated film becomes small. The anionic surfactant compound preferably has a reference structure in which aromatic rings or heterocyclic rings constituting the molecule are arranged isotropically. In such an anionic surfactant compound having a molecular structure with geometric contrast, intramolecular polarization does not occur in the molecular plane. Therefore, the optical anisotropy of the anionic surfactant compound can satisfy the above formula (1), and a more desirable optical anisotropy can be expressed.

  Examples of the polycyclic compound in which X in the above formula (21) is an aromatic ring group include, for example, a sulfonic acid at an aromatic nucleus located at both molecular terminals of a biphenyl group, a terphenyl group, a quaterphenyl group, or a derivative group thereof. Derivatives (modified products) into which a group has been introduced are exemplified. The polycyclic compound preferably has a biphenyl group, a terphenyl group, a quaterphenyl group, or a derivative group thereof. The polycyclic compound is, for example, a neutralized salt. The polycyclic compound may have various functional groups. When the polycyclic compound has various functional groups, the polycyclic compound preferably has various functional groups as long as intramolecular polarization is not caused.

(Aqueous solution or aqueous dispersion)
The aqueous solution or aqueous dispersion for forming the optically anisotropic layer contains the water-soluble resin and the anionic surfactant compound.

  In the aqueous solution or dispersion, the content of the anionic surfactant compound is preferably 0.1 to 500 parts by weight with respect to 100 parts by weight of the water-soluble resin. The more preferable lower limit of the content of the anionic surfactant compound is 1 part by weight, the still more preferable lower limit is 5 parts by weight, the more preferable upper limit is 300 parts by weight, and the particularly preferable upper limit is 100 parts by weight relative to 100 parts by weight of the water-soluble resin. Parts by weight. When the content of the anionic surfactant compound satisfies the above lower limit, the wettability of the aqueous solution or aqueous dispersion is further increased, coat spots are less likely to occur during coating, and the appearance of the coating film is improved. The uniformity of the optically anisotropic layer is improved. For this reason, the optical compensation performance is further enhanced. When the content of the anionic surfactant compound satisfies the above upper limit, the front retardation R0 defined by the formula (2) and the NZ coefficient defined by the formula (3) can be easily controlled within a desired range, and more An optical compensation laminated film having more desirable optical compensation performance can be obtained.

  In the aqueous solution or aqueous dispersion, the content of the anionic surfactant compound is preferably 0.1% by weight or more in a total of 100% by weight of the water-soluble resin and the anionic surfactant compound. It is more preferably 1% by weight or more, and preferably 70% by weight or less. Correspondingly, in 100% by weight of the optically anisotropic layer, the content of the anionic surfactant compound is preferably 0.1% by weight or more, more preferably 1% by weight or more, and 70% by weight. % Or less is preferable. When the content of the anionic surfactant compound satisfies the above lower limit, the wettability of the aqueous solution or aqueous dispersion is further increased, coat spots are less likely to occur during coating, and the appearance of the coating film is improved. The uniformity of the optically anisotropic layer is improved. For this reason, the optical compensation performance is further enhanced. When the content of the anionic surfactant compound satisfies the above upper limit, the front retardation R0 defined by the formula (2) and the NZ coefficient defined by the formula (3) can be easily controlled within a desired range, and more An optical compensation laminated film having more desirable optical compensation performance can be obtained.

  Since the aqueous solution or aqueous dispersion has lyotropic liquid crystallinity, it is molecularly oriented by coating shear force. Therefore, the solid content concentration that affects the viscosity of the aqueous solution or aqueous dispersion is important. The solid concentration in the aqueous solution or aqueous dispersion is preferably 1 to 30% by weight. The more preferable lower limit of the solid content concentration in the aqueous solution or the aqueous dispersion is 3% by weight, and the more preferable upper limit is 20% by weight. When the solid content concentration satisfies the lower limit, it is possible to obtain an optical compensation laminated film having sufficient molecular anisotropy and more desirable optical anisotropy by coating shear force. When the solid content concentration satisfies the above upper limit, the fluidity after coating increases, and the wettability of the aqueous solution or aqueous dispersion with respect to the base film is further increased.

  In the above aqueous solution or aqueous dispersion, an antistatic agent, an antioxidant, an inorganic lubricant, an organic lubricant, an emulsifier, a pH adjuster, an ultraviolet absorber, an antifoaming agent, a facial dye and Various additives such as a crystal nucleating agent may be blended.

(Base film)
The base film is preferably optically transparent and has little residual retardation. Examples of the material for the base film include acrylic, polyester, polypropylene, triacetyl cellulose, cycloolefin, polycarbonate, polysulfone, polyarylate, and glass.

  The average thickness of the base film is not particularly limited. In consideration of the weight reduction of a member that is important when laminated on a liquid crystal display device so that the predetermined optical compensation performance is not impaired and has a certain mechanical strength, the above base film The thickness of is appropriately set. The average thickness of the substrate film is preferably 20 to 200 μm. The minimum with more preferable average thickness of the said base film is 40 micrometers, and a more preferable upper limit is 100 micrometers.

  The surface of the base film may be subjected to surface activation treatment such as corona treatment, plasma treatment, ultraviolet irradiation or various chemical treatments. Further, by performing various functional coatings or laminations by coating or vapor deposition, various performances can be added to the base film, and the utility value of the base film can be further improved.

  The base film is preferably not rubbed. However, the base film may be rubbed. Since the water-soluble resin has lyotropic liquid crystallinity, the water-soluble resin can be oriented by a coating shear force during coating even if the base film is not rubbed. Therefore, in order to control the liquid crystal alignment, the base film does not need to have a layer such as an alignment film, and the base film does not need to be rubbed. As a result, an optical compensation laminated film that hardly causes optical defects can be obtained.

(Optical anisotropic layer and optical anisotropic layer forming method)
The method for applying the aqueous solution or aqueous dispersion on the base film is not particularly limited. As the coating method, various coating methods capable of forming an optically transparent and homogeneous film are appropriately used. Examples of the coating method include die coating method, bar coating method, roll coating method, knife coating method, gravure coating method, micro gravure coating method, offset gravure coating method, lip coating method, dipping method, spray coating method and spin coating method. Examples thereof include a coating method. One of these coating methods may be used, or two or more methods may be used. In order to impart sufficient shearing force to the coating film during coating and to effect molecular orientation effectively by the coating shearing force, a die coating method, a bar coating method or a spray coating method is preferred.

  The coating speed when the aqueous solution or aqueous dispersion is applied on the base film is preferably 100 mm / second or more. In order to obtain an optical compensation laminated film according to the present invention, an optically anisotropic layer is formed by applying the aqueous solution or aqueous dispersion at a coating speed of 100 mm / second or more on at least one surface of the base film. Is preferred. Since the water-soluble resin having lyotropic liquid crystallinity is molecularly oriented by coating shear force, the orientation of liquid crystal resin molecules can be precisely controlled by increasing the coating speed as much as possible.

  The coating speed can be controlled and defined by the running speed of the base film during coating. When the coating speed is 100 mm / second or more, the liquid crystal resin molecules are sufficiently aligned, and as a result, high optical anisotropy is obtained, and the optical compensation performance such as front retardation R 0 can be further enhanced. Further, the optical axis accuracy can be sufficiently expressed, and as a result, display unevenness is hardly generated, and the display quality of the liquid crystal display device can be improved. The optical axis accuracy is one of the optical performances that greatly affects the liquid crystal display device, particularly the viewing angle characteristics and contrast.

  The coating speed is preferably 5000 mm / second or less, more preferably 2000 mm / second or less, and still more preferably 1000 mm / second or less. In this case, uneven coating is less likely to occur, and the uniformity of the optically anisotropic layer can be further enhanced.

  An optically anisotropic layer can be formed by applying the aqueous solution or aqueous dispersion on the base film and then drying and removing the water in the coating film. The drying temperature is preferably not higher than the glass transition temperature of the substrate film and not higher than the boiling point of water as a solvent. It is preferable to dry so as not to break the orientation of the liquid crystal resin molecules after coating. The drying temperature is preferably 10 to 100 ° C. The preferable lower limit of the drying temperature is 20 ° C, and the preferable upper limit is 60 ° C.

  In the case of drying by applying hot air or the like to the coating film, the wind pressure is not disturbed by the mechanical load on the undried coating film, and the thermal load on the base film and coating film is not disturbed. It is set appropriately so as not to become too large. The wind pressure is preferably 0.1 to 1.0 MPa. The preferable lower limit of the wind pressure is 0.3 MPa, and the preferable upper limit is 0.8 MPa.

  The drying time is preferably 5 seconds to 1 hour. A more preferable lower limit of the drying temperature is 10 seconds, a further preferable lower limit is 20 seconds, a more preferable upper limit is 30 minutes, and a still more preferable upper limit is 10 minutes. If the drying time is too short, the solvent becomes insufficiently volatilized and the coating film becomes brittle. If the drying time is too long, the orientation of the liquid crystal resin molecules constituting the optical anisotropic layer is relaxed, and the optical compensation performance tends to be lowered.

(Optical compensation laminated film)
The optical compensation laminated film according to the present invention preferably has a front retardation R0 (nm) defined by the following formula (2) of 50 to 500 nm.

R0 (nm) = | nx−ny | × d (2)
In the above formula (2), nx represents the maximum refractive index in the optical compensation laminated film surface, ny represents the refractive index in the direction perpendicular to the nx direction in the optical compensation laminated film surface, and d represents the optical compensation laminated film. Represents the average thickness (nm).

  When the front retardation R0 is 50 to 500 nm, when the optical compensation laminated film is incorporated in a liquid crystal display device, a display image can be made high quality. When the front retardation R0 deviates from the range of 50 to 500 nm, birefringence when passing through the liquid crystal cannot be fully compensated, and the commercial value as an optical compensation laminated film is lowered.

  In the optical compensation laminated film according to the present invention, the NZ coefficient defined by the following formula (3) is preferably 0.0 to 5.0.

Nz coefficient = (nx−nz) / (nx−ny) (3)
In the above formula (3), nx represents the maximum refractive index in the optical compensation laminated film surface, ny represents the refractive index in the direction orthogonal to the nx direction in the optical compensation laminated film surface, and nz represents the nx direction and the ny direction. Represents the refractive index in the direction orthogonal to

  When the optical compensation laminated film is incorporated in a liquid crystal display device having an NZ coefficient of 0.0 to 5.0, the viewing angle of the liquid crystal display device can be widened and the contrast can be increased. Therefore, the display image of the liquid crystal display device can be improved.

  In the optical compensation laminated film according to the present invention, the optical axis with respect to the width direction of the optical compensation laminated film is preferably within 0.5 °. When an optical compensation laminated film having an optical axis of 0.5 ° or less is incorporated in a liquid crystal display device, high viewing angle compensation performance is exhibited, display unevenness is eliminated, and a display image can be stabilized.

  The haze value of the optical compensation laminated film is preferably 5% or less, more preferably 3% or less, and particularly preferably 1% or less. As the haze value is lower, light leakage or the like is less likely to occur when the optical compensation laminated film is used for a polarizing plate protective film or the like.

  It is also possible to further increase the film strength or appearance of the optically anisotropic layer by immersing the optical compensation laminated film in various treatment liquids and performing chemical treatment. The surface of the optical compensation laminated film may be subjected to surface activation treatment such as corona treatment, plasma treatment, ultraviolet irradiation, and various chemical treatments. By applying various functional coatings or laminations by coating or vapor deposition to the surface of the optical compensation laminated film, various performances can be added to the optical compensation laminated film, and the utility value of the optical compensation laminated film can be further improved. it can.

  Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to these examples.

(Example 1 of preparation of aqueous solution or aqueous dispersion containing water-soluble resin and surfactant compound)
Aromatic polyamide resin (polycondensate of 50 mol% of terephthalate component and 50 mol% of disulfonylbenzidine component) was added to ion-exchanged water to obtain an aqueous solution containing 10 wt% of aromatic polyamide resin. The solution was stirred for 30 minutes while keeping the temperature at 50 ° C. using an ultrasonic stirring device. Thereafter, diammonium terphenyl disulfonate (refractive index: nx = 1.69, ny = 1.69, nz = 1.56) was added to the solution, and the terphenyl disulfonic acid diamide with respect to 100 parts by weight of the aromatic polyamide resin. It added so that the addition amount of ammonium might be 30 weight part, and also stirred for 30 minutes, keeping solution at 50 degreeC, and obtained aqueous solution (1).

(Example 2 of preparation of aqueous solution or aqueous dispersion containing water-soluble resin and surfactant compound)
Except that the amount of diammonium terphenyl disulfonate was changed so that the amount of diammonium terphenyl disulfonate relative to 100 parts by weight of the aromatic polyamide resin was 10 parts by weight, the same procedure as in Preparation Example 1 was performed. An aqueous solution (2) was obtained.

(Example 3 of preparation of aqueous solution or aqueous dispersion containing water-soluble resin and surfactant compound)
Except that the amount of diammonium terphenyl disulfonate was changed so that the amount of diammonium terphenyl disulfonate was 50 parts by weight with respect to 100 parts by weight of the aromatic polyamide resin, the same procedure as in Preparation Example 1 was performed. To obtain an aqueous solution (3).

(Example 4 of preparation of aqueous solution or aqueous dispersion containing water-soluble resin and surfactant compound)
An aqueous solution in the same manner as in Preparation Example 1, except that diammonium terphenyl disulfonate was changed to diammonium biphenyl disulfonate (refractive index: nx = 1.70, ny = 1.70, nz = 1.55). (4) was obtained.

(Example 5 of preparation of aqueous solution or aqueous dispersion containing water-soluble resin and surfactant compound)
Except that diammonium terphenyl disulfonate was changed to diammonium quaterphenyl disulfonate (refractive index: nx = 1.67, ny = 1.67, nz = 1.58), the same as adjustment example 1 To obtain an aqueous solution (5).

(Example 6 of preparation of aqueous solution or aqueous dispersion containing water-soluble resin and surfactant compound)
Except that the amount of diammonium terphenyl disulfonate was changed so that the amount of diammonium terphenyl disulfonate relative to 100 parts by weight of the aromatic polyamide resin was 300 parts by weight, the same procedure as in Preparation Example 1 was performed. To obtain an aqueous solution (6).

(Example 7 of preparation of aqueous solution or aqueous dispersion containing water-soluble resin)
An aqueous solution (7) was obtained in the same manner as in Preparation Example 1 except that diammonium terphenyl disulfonate was not added.

(Preparation example 8 of aqueous solution or aqueous dispersion containing water-soluble resin and surfactant compound)
An aqueous solution (8) was obtained in the same manner as in Preparation Example 1 except that the aromatic polyamide resin was changed to a sulfonated poly-ε-capramide (not having lyotropic liquid crystallinity), which is an aliphatic polyamide resin. .

(Preparation example 9 of aqueous solution or aqueous dispersion containing water-soluble resin and surfactant compound)
An aqueous solution (9) is obtained in the same manner as in Preparation Example 1 except that the aromatic polyamide resin is changed to a sulfonated product of polyhexamethylene adipamide (which does not have lyotropic liquid crystallinity), which is an aliphatic polyamide resin. It was.

(Preparation example 10 of aqueous solution or aqueous dispersion containing water-soluble resin and surfactant compound)
An aqueous solution (10) was obtained in the same manner as in Preparation Example 1, except that the aromatic polyamide resin was changed to a sulfonated product of polybutylene isophthalate, which is an aromatic polyester resin (not having lyotropic liquid crystallinity).

(Preparation Example 11 of aqueous solution or aqueous dispersion containing water-soluble resin and surfactant compound)
An aqueous solution (12) was obtained in the same manner as in Preparation Example 1 except that diammonium terphenyl disulfonate was changed to an acetylene glycol surfactant (trade name “Olfin E1004”, manufactured by Nissin Chemical Industry Co., Ltd.). .

(Preparation example 1 of base film)
A polyethylene terephthalate resin (melting point: 259 ° C., glass transition temperature: 69 ° C., manufactured by Unitika Ltd., hereinafter sometimes referred to as PET) was prepared. This polyethylene terephthalate resin was supplied to a uniaxial melt extrusion molding apparatus at 280 ° C., melt-kneaded, and melt-extruded into a film form from a T die attached to the tip of the extrusion apparatus. The melt-extruded film was brought into close contact with a 20 ° C. rotating drum by a pinning wire method and quenched. Thereafter, a 25-μm-thick biaxially stretched PET film (Mitsubishi Chemical Polyester Film Co., Ltd.) is wound into a roll while being laminated as an anti-blocking sandwich paper, and a base film (A) having a width of 650 mm and an average thickness of 100 μm ( An unstretched PET film) was obtained. In the production of the base film, the surface of the base film was not rubbed.

(Production Example 2 of base film)
The polyethylene terephthalate resin was changed to a norbornene-based resin (trade name “ZEONOR 1600”, glass transition temperature: 168 ° C., manufactured by Nippon Zeon Co., Ltd., hereinafter sometimes referred to as COP), and the extrusion temperature was changed from 280 ° C. to 300 ° C. A base film (B) (unstretched COP film) having a width of 650 mm and an average thickness of 80 μm was produced in the same manner as in Production Example 1 except that the temperature was changed to ° C.

(Production Example 3 of Base Film)
After rubbing the surface of the base film (A) obtained in Production Example 1 with nylon 6 felt, the treated surface was washed with shower jet water, and residual moisture on the surface was removed with compressed air. A base film (C) (unstretched PET film) was prepared.

Example 1
A slot die coat in which the substrate film (A) is corona-treated at an output of ² kW / m ² while being continuously unwound by roll conveyance at a constant speed of 500 mm / second, and then the flow rate is adjusted to a coating liquid discharge rate of 30 g / min. The aqueous solution (1) was applied onto the base film at a coating speed of 500 mm / sec using a coating film to form a coating film. Thereafter, the base film on which the coating film was formed was immediately introduced into a heating furnace, and the surface of the coating film was subjected to a drying treatment for 20 seconds with hot air compressed at a temperature of 50 ° C. and a wind pressure of 0.5 Mpa. After cooling to room temperature, it was wound up in a roll shape on a winding core at a winding tension of 100 N / m to obtain an optical compensation laminated film.

(Examples 2-12 and Comparative Examples 1-5)
Example 1 except that the type of the base film was changed as shown in Table 1 below, and the type of the aqueous solution coated on the base film and the transport speed (coating speed) of the base film were changed as shown in Table 1 below. Similarly, an optical compensation laminated film was obtained.

(Evaluation)
(1) Coating property When the aqueous solution was coated on the base film, the appearance of the coating film was visually observed, and the coating property was evaluated according to the following criteria.

[Criteria for coating properties]
○: Coating streaks and repelling did not occur, and coating could be applied uniformly without causing poor coating appearance. ×: Coating streaks or repelling occurred, resulting in poor coating appearance and stable. It was difficult to apply

(2) Appearance of optical compensation laminated film The obtained optical compensation laminated film was sandwiched between polarizing plates arranged in crossed Nicols and observed visually, and the appearance of the optical compensation laminated film was evaluated according to the following criteria.

[Appearance of optical compensation laminated film]
○: Color unevenness and light leakage of any shape of dot shape, line shape, and planar shape were not recognized, and the appearance was homogeneous. ×: At least within point shape, line shape or surface color unevenness and light leakage. One was confirmed and had a partially heterogeneous appearance

(3) Front retardation value R0 of optical compensation laminated film
Using an automatic birefringence measuring device (manufactured by Oji Scientific Instruments, model number “KOBRA-WR”), the wavelength of the measuring light is set to 550 nm, and the axis perpendicular to the longitudinal direction of the optical compensation laminated film is used as the reference axis. The film was measured at intervals of 50 mm in the width direction, and the average value was calculated as the front retardation value R0 of the optical compensation laminated film.

(4) NZ coefficient of the optical compensation laminated film Using an automatic birefringence measuring apparatus (manufactured by Oji Scientific Instruments, model number “KOBRA-WR”), the wavelength of the measuring light is set to 550 nm and orthogonal to the longitudinal direction of the optical compensation laminated film. The optical compensation laminated film was measured at intervals of 50 mm in the width direction, and the average value was calculated as the NZ coefficient of the optical compensation laminated film.

(5) Haze of optical compensation laminated film Using an haze meter (manufactured by Tokyo Denshoku Co., Ltd., model number “TC-H3DPK”), the optical compensation laminated film is measured at intervals of 50 mm in the width direction, and an average value is calculated. And the haze of the optical compensation laminated film.

  The results are shown in Tables 1 and 2 below.

DESCRIPTION OF SYMBOLS 1 ... Optical compensation laminated film 2 ... Base film 2a ... 1st surface 2b ... 2nd surface 3 ... Optical anisotropic layer

Claims (5)

A base film;
An optically anisotropic layer laminated on at least one side of the base film,
An optical compensation laminated film, wherein the optical anisotropic layer is formed of an aqueous solution or an aqueous dispersion containing a water-soluble resin having lyotropic liquid crystallinity and an anionic surfactant compound having two or more sulfonic acid groups.   The optical compensation laminated film according to claim 1, wherein the water-soluble resin is an aromatic polyamide resin.   The optical compensation laminated film according to claim 1, wherein the surface active compound is a polycyclic phenyl compound. The refractive index anisotropy of the surface active compound satisfies the following formula (1),
The front retardation R0 (nm) defined by the following formula (2) is in the range of 50 to 500 nm, and
The optical compensation laminated film according to any one of claims 1 to 3, wherein an NZ coefficient defined by the following formula (3) is within a range of 0.0 to 5.0.
nx = ny> nz (1)
In the above formula (1), nx represents the maximum refractive index of the surfactant compound, ny represents the refractive index in the direction orthogonal to the nx direction in the surface of the surfactant compound, and nz is orthogonal to the nx direction and the ny direction. Refractive index in the direction of
R0 (nm) = | nx−ny | × d (2)
In the above formula (2), nx represents the maximum refractive index in the optical compensation laminated film surface, ny represents the refractive index in the direction perpendicular to the nx direction in the optical compensation laminated film surface, and d represents the optical compensation laminated film. Represents the average thickness (nm).
Nz coefficient = (nx−nz) / (nx−ny) (3)
In the above formula (3), nx represents the maximum refractive index in the optical compensation laminated film surface, ny represents the refractive index in the direction orthogonal to the nx direction in the optical compensation laminated film surface, and nz represents the nx direction and the ny direction. Represents the refractive index in the direction orthogonal to A method for producing the optical compensation laminated film according to any one of claims 1 to 4,
Using an aqueous solution or aqueous dispersion containing a water-soluble resin having lyotropic liquid crystallinity and an anionic surfactant compound having two or more sulfonic acid groups,
The manufacturing method of the optical compensation laminated | multilayer film which apply | coats the said aqueous solution or aqueous dispersion to the at least single side | surface of a base film at a coating speed of 100 mm / sec or more, and forms an optical anisotropic layer.

Images