JP2009251530A - Coating film for optical compensation, optical element and manufacturing method of coating film for optical compensation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating film for optical compensation for which a complicated step is not needed and by which control of the retardation to each wavelength of light is made easy. <P>SOLUTION: The coating film 1 for optical compensation is formed by applying a solution or a melted product of a liquid crystalline polymer on a substrate 10 while aligning the solution or the melted product in a direction parallel to the surface of the substrate 10. The surface of the coating film 1 for optical compensation has a projecting and recessed shape wherein recessed parts 2 and projecting parts 3 are repeated and when retardation values to light having 548 nm wavelength in the projecting part 3 are defined as r (nm)and retardation value to the light having 548 nm wavelength in the recessed part 2 are defined as r' (nm), respectively, r-r'≥10 is satisfied. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a coating film for optical compensation that can be suitably used for an optical device such as a liquid crystal display device and an optical pickup, an optical element using the coating film, and a manufacturing method thereof.

  Various optical devices such as liquid crystal display devices use various films together with a liquid crystal cell, a polarizer, and the like. In the specification of the present application, the term “film” refers to a layer formed directly on another substrate, a film taken off from the substrate, and a film formed by direct solution casting, melt casting, etc. Shall be included.

  In particular, a film for optical compensation for compensating birefringence caused by other configurations in the apparatus is generally used. Applications of such an optical compensation film include, for example, widening the viewing angle and preventing color leakage during black display. In addition, as a material for forming such an optical compensation film, for example, a polymer such as polycarbonate, polyester, polystyrene, polyamide, polyimide, polyethersulfone, or the like is used. The film is incorporated into various devices through a stretching process (retarding) and a bonding process. However, this method requires not only film formation but also labor for pasting the film, and a simpler method has been demanded.

  Therefore, as an alternative method for producing a film for optical compensation, a liquid crystalline acrylate is supported on a support subjected to an alignment treatment, and the monomer is polymerized by irradiation with radiation while maintaining the liquid crystal state. A method for forming a film has been proposed (see, for example, Patent Document 1). In addition, a method of forming a thin film having a phase difference by aligning liquid crystal without using an alignment film by applying a polymer liquid crystal while applying a shear stress has been proposed (see, for example, Patent Document 2). .

  By the way, in order to use the optical compensation film for preventing discoloration during display of a liquid crystal display device or the like, it is necessary to control the phase difference (wavelength dispersion of the phase difference) with respect to each wavelength of light. As an example of such, there is a retardation plate or the like whose phase difference is 1/4 of the wavelength for each wavelength of light. Examples of such a controlled phase difference in a wide band include, for example, (retardation in light with a wavelength of 450 nm) / (retardation in light with a wavelength of 550 nm) and films having different retardations and their optical axes intersect. In this state, there are retardation plates that are stacked in a state (see, for example, Patent Document 3).

Another example is a film composed of a polymer containing a polymer monomer unit having a positive refractive index anisotropy and a polymer monomer unit having a negative refractive index anisotropy ( For example, see Patent Document 4). Another example is a surface relief hologram using structural birefringence (see, for example, Patent Document 5).
JP-A-62-70406 (published on March 31, 1987) JP 62-227122 A (released on October 6, 1987) Japanese Patent Laid-Open No. 5-27118 (published February 5, 1993) International Publication No. WO 00/26705 (released on February 5, 2002) Japanese Patent Application Laid-Open No. Sho 62-212940 (published on September 18, 1987)

  However, in the techniques described in Patent Documents 3 to 5, in order to control the phase difference with respect to each wavelength of light, it is necessary to bother the pasting after filming or fine processing. Patent Documents 1 and 2 only describe a method for forming a retardation layer, and do not disclose controlling the phase difference for each wavelength of light.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a coating film for optical compensation that does not require a complicated process and can easily control the phase difference for each wavelength of light. There is to do.

The optical compensation coating film according to the present invention is formed by applying a solution or melt of a liquid crystalline polymer on a substrate while aligning it in a direction parallel to the surface of the substrate in order to solve the above-described problems. The coating film for optical compensation has a concavo-convex shape in which a concave portion and a convex portion are repeated, and a phase difference with respect to light having a wavelength of 548 nm in the convex portion is defined as r (nm). When the phase difference with respect to light having a wavelength of 548 nm is r ′ (nm), the following formula (1)
r−r ′ ≧ 10 Formula (1)
It is characterized by satisfying.

  According to the above configuration, since the liquid crystalline polymer solution or melt is formed on the substrate while being oriented in a direction parallel to the surface of the substrate, the coating film for optical compensation is a stretching step. In this case, birefringence is exhibited when viewed from a direction perpendicular to the substrate.

  The phase difference r (nm) with respect to light having a wavelength of 548 nm in the convex portion and the phase difference r ′ (nm) with respect to light having a wavelength of 548 nm in the concave portion satisfy Expression (1).

  The phase difference described here is a phase difference when viewed from a direction perpendicular to the surface of the optical compensation coating film. In this specification, when there is no particular reference to the angle with respect to the light incident surface, the “phase difference” means a phase difference when viewed from a direction perpendicular to the surface of the optical compensation coating film.

  According to the above configuration, when the distance between the optical compensation coating film and a person viewing the optical compensation coating film is ensured such that the convex portions and the concave portions are invisible to the human eye, The entire area including the recess is viewed macroscopically.

  At this time, the combined phase difference R of the entire region including the convex portion and the concave portion indicates a phase difference corresponding to the average birefringence of birefringence due to the phase differences r and r ′ of the convex portion and the concave portion. Therefore, the wavelength dependency of the phase differences r and r ′ in the convex portions and the concave portions is different from the wavelength dependency of the combined phase difference R in the entire region including all the convex portions and the concave portions.

  The wavelength dependence (wavelength dispersion) of the composite phase difference is determined by the difference in phase difference between the convex portion and the concave portion and the area ratio of the convex portion and the concave portion with respect to the entire region. Therefore, the chromatic dispersion of the composite phase difference can be easily controlled without being restricted by the material.

  As described above, according to the present invention, the liquid crystal polymer is applied while being oriented, and at this time, the optical phase with which the phase difference for each wavelength of light can be easily controlled by a simple process of simply forming an uneven shape on the surface. A compensation coating film can be provided.

Furthermore, the coating film for optical compensation of the present invention has the following mathematical formula (2), where R (λ) is the combined phase difference with respect to light having a wavelength of λ nm in the entire region including all the convex portions and concave portions.
R (548) ≦ 350 nm Formula (2)
It is preferable to satisfy.

  As a retardation film for optical compensation for a high-quality liquid crystal display device, it is necessary that the retardation is generally 350 nm or less. Therefore, it can be suitably used for a liquid crystal display device with the above configuration.

Furthermore, the coating film for optical compensation of the present invention has a phase difference with respect to light having a wavelength of λ nm at the convex portion as r (λ), and a phase difference with respect to light with a wavelength of λ nm in the concave portion as r ′ (λ). When the combined phase difference with respect to light of wavelength λ nm in the entire region including all of the portions and the recesses is R (λ), the following formulas (3), (4), and (5)
r (548) <r (447) Formula (3)
r ′ (548) <r ′ (447) Formula (4)
R (548) ≧ R (447) Formula (5)
It is preferable to satisfy.

  The phase difference when many liquid crystalline polymers are aligned shows positive wavelength dispersion. Therefore, since satisfying the formulas (3) and (4), many liquid crystalline polymers can be used, and the range of selection of materials is widened.

  On the other hand, as described above, the wavelength dependence (wavelength dispersion) of the composite phase difference R is determined by the difference in phase difference between the convex portion and the concave portion and the area ratio of the convex portion and the concave portion with respect to the entire region. These are easily controlled by appropriately selecting them. And when satisfy | filling Numerical formula (5), a synthetic | combination phase difference will show reverse wavelength dispersion. That is, the optical compensation coating film can be used as a retardation film exhibiting reverse wavelength dispersion.

Further, when the combined phase difference with respect to light having a wavelength of λ nm in the entire region including all the convex portions and the concave portions is R (λ), the following formula (6)
R (628) ≧ R (548) ≧ R (447) Formula (6)
It is preferable to satisfy.

  This makes it possible to easily realize an optical compensation coating film exhibiting reverse wavelength dispersion and to control the degree of wavelength dispersion. Further, it is possible to easily realize an optical compensation coating film having a wavelength dispersion with a large inclination in a graph in which the vertical axis represents the phase difference and the horizontal axis represents the wavelength.

  Furthermore, in the coating film for optical compensation of the present invention, the liquid crystalline polymer is preferably a cellulose derivative.

  As a result, it is possible to reduce the thickness of the film to obtain the necessary phase difference, and it can be obtained at a low cost.

  Furthermore, the cellulose derivative is preferably a compound in which at least one of the hydrogen atoms of the hydroxyl group of cellulose is substituted with an alkyl group having 1 to 20 carbon atoms and / or a cyanoalkyl group having 1 to 20 carbon atoms. For example, at least one selected from methyl cellulose, ethyl cellulose, and cyanoethyl cellulose.

  Since these substances are excellent in stability of physical properties such as low hydrolyzability and low hygroscopicity, they have good durability when used as a coating film for optical compensation.

  In addition, an optical element of the present invention includes a light-transmitting substrate and the above-described optical compensation coating film formed on the light-transmitting substrate.

  Thereby, the coating film for optical compensation can be used without peeling from the substrate. A light-transmitting substrate can also be used as a part of an optical element (for example, a polarizing plate) in the optical device.

The method for producing an optical compensation coating film of the present invention is a method for producing an optical compensation coating film in which an optical compensation coating film is formed by a coating process of coating a liquid crystalline polymer solution or melt on a substrate. In the coating step, the liquid crystalline polymer is oriented in a direction parallel to the surface of the substrate, and the surface of the coating film for optical compensation has a concavo-convex shape in which a concave portion and a convex portion are repeated, The phase difference r (nm) for light having a wavelength of 548 nm in the convex portion and the phase difference r ′ (nm) for light having a wavelength of 548 nm in the concave portion are expressed by the following formula (1).
r−r ′ ≧ 10 Formula (1)
The liquid crystalline polymer solution or melt is applied so as to satisfy the above condition.

  According to the above configuration, since the liquid crystalline polymer solution or melt is formed on the substrate while being oriented in a direction parallel to the surface of the substrate, the coating film for optical compensation is a stretching step. In this case, birefringence is exhibited when viewed from a direction perpendicular to the substrate.

  And as above-mentioned, the synthetic | combination phase difference R of the whole area | region including a convex part and a recessed part shows the phase difference corresponding to the average birefringence of the birefringence by the phase difference r and r 'of a convex part and a recessed part. . Therefore, the wavelength dependence of the phase differences r and r ′ in each convex part and the concave part is different from the wavelength dependence of the combined phase difference R in the entire region including all convex parts and concave parts.

  The wavelength dependence (wavelength dispersion) of the composite phase difference is determined by the difference in phase difference between the convex portions and the concave portions and the area ratio of the convex portions and the concave portions with respect to the entire region. Therefore, the chromatic dispersion of the composite phase difference can be easily controlled without being restricted by the material.

  As described above, according to the present invention, the liquid crystal polymer is applied while being oriented, and at this time, the optical phase with which the phase difference for each wavelength of light can be easily controlled by a simple process of simply forming an uneven shape on the surface. A compensation coating film can be provided.

  Furthermore, the method for producing a coating film for optical compensation according to the present invention includes applying the solution or melt of the liquid crystalline polymer by applying a stress in a direction parallel to the surface of the substrate. Is preferably oriented in a direction parallel to the surface of the substrate.

  Thereby, the liquid crystalline polymer can be aligned without forming an alignment film or the like, and the manufacturing process can be simplified.

  Furthermore, in the method for producing an optical compensation coating film of the present invention, it is preferable to apply the liquid crystalline polymer solution or melt on the substrate in a plurality of times.

  According to the above configuration, when the coating is applied a plurality of times, stress is applied in a direction parallel to the surface of the substrate at the interface with the liquid crystal polymer solution or melt layer previously applied. . As a result, the liquid crystalline polymer can be easily aligned.

  Furthermore, the method for producing a coating film for optical compensation according to the present invention comprises the step of coating the surface of the coating film for optical compensation by coating the liquid crystalline polymer solution or melt with a coating member having a concavo-convex surface. The shape is preferred.

The coating film for optical compensation according to the present invention is a coating film for optical compensation formed by coating a liquid crystalline polymer solution or melt on a substrate while being oriented in a direction parallel to the surface of the substrate. The surface has a concavo-convex shape in which a concave portion and a convex portion are repeated, and a phase difference with respect to light with a wavelength of 548 nm at the convex portion is defined as r (nm), and a phase difference with respect to light with a wavelength of 548 nm in the concave portion is defined as When r ′ (nm), the following formula (1)
r−r ′ ≧ 10 Formula (1)
Meet.

  As a result, it is possible to provide an optical compensation coating film that does not require a complicated process and that can easily control the phase difference for each wavelength of light.

  One embodiment of the optical compensation coating film of the present invention will be described below with reference to FIGS.

(About structure)
The configuration of the optical compensation coating film according to this embodiment will be described with reference to FIG. 1A and 1B are diagrams illustrating an example of an optical compensation coating film according to the present embodiment, in which FIG. 1A is a perspective view and FIG. 1B is a cross-sectional view.

  As shown in FIG. 1, the optical compensation coating film 1 is a film formed by applying a solution in which a liquid crystalline polymer is dissolved in a solvent or a melt of the liquid crystalline polymer on a substrate 10. . In the optical compensation coating film 1, the liquid crystalline polymer is aligned in a direction parallel to the upper surface of the substrate 10. Thereby, when viewed from a direction perpendicular to the substrate 10, the optical compensation coating film 1 has a birefringence Δn. In the present embodiment, it is preferable that the birefringence Δn of the optical compensation coating film 1 with respect to light having a wavelength of 548 nm satisfies 0.001 ≦ Δn ≦ 0.35.

  Further, the optical compensation coating film 1 has a concavo-convex shape in which one surface thereof is alternately repeated with the concave portions 2 and the convex portions 3. In addition, in FIG.1 (b), although the cross-sectional sawtooth-shaped uneven | corrugated shape is shown, a shape is not limited to this, The recessed part 2 and the convex part 3 should just be repeated alternately. For example, the cross section may be a curve such as a trigonometric function.

  As described above, the optical compensation coating film 1 has birefringence when viewed from the vertical direction. The thicknesses of the concave portion 2 and the convex portion 3 are different. In general, the phase difference Re is expressed by Re = Δn × d from the birefringence Δn and the thickness d. Therefore, the phase difference is different between the concave portion 2 and the convex portion 3.

  In the present embodiment, the thickness of the concave portion 2 and the convex portion 3 is set so that the difference in phase difference between the adjacent concave portion 2 and the convex portion 3 with respect to light having a wavelength of 548 nm is 10 nm or more.

  Here, the boundary between the concave portion 2 and the convex portion 3 is determined as follows. That is, the position coordinates of the surface of the optical compensation coating film 1 are represented by coordinates on the X axis and the Y axis, which are two axes on the surface of the film, and the phase difference at the coordinates (x, y) is represented by r (x , Y) and when the total area of the film surface is A,

What is necessary is just to set the line which connects the coordinate which has the average phase difference _rAVE represented by these to the boundary of the recessed part 2 and the convex part 3. FIG. By performing such setting, a region having a phase difference r (x, y) greater than or equal to the average phase difference r _AVE and continuing along the film surface becomes the convex portion 3, which is less than the average phase difference r _AVE. A region having a phase difference r (x, y) of 2 and continuous along the film surface is the recess 2.

  The optical compensation coating film 1 according to this embodiment may be used in a state where it is applied to the substrate 10 or may be used in a state where it is peeled off from the substrate 10. When the optical compensation coating film 1 is used while being applied to the substrate 10, the optical element 11 including the optical compensation coating film 1 and the substrate 10 is incorporated into the optical apparatus.

  The phase difference r (λ) nm of the convex portion 3 of the optical compensation coating film 1 is obtained as follows, for example.

A film having a phase difference r _ef (nm) is arranged between a pair of polarizing plates having parallel polarization directions so that the slow axis is deviated from the polarization direction of the polarizing plate by 45 °, and the wavelength λ (nm) from one polarizing plate The relationship between the transmittance I (λ) when the linearly polarized light passes through the film and the other polarizing plate and the phase difference _ref for the light of wavelength λ is
I (λ) = 1/2 + 1/2 · cos (2πr _ef / λ)
In the case of the optical compensation coating film 1 in which a plurality of concave portions 2 and a plurality of convex portions 3 exist along a direction parallel to the light incident surface, the phase difference r (λ) of the convex portions 3 is expressed. The resulting transmittance is obtained, the phase difference indicating the transmittance is calculated based on the above relational expression, and the value is set as the phase difference r (λ).

  Or when measuring the phase difference of a minute unit area, it can measure using a micro polarization spectrophotometer. For example, by using a liquid crystal cell gap measuring device (TFM-120AFT-PC) using a micro-polarization spectrophotometer manufactured by Oak Manufacturing Co., Ltd., it is possible to measure the phase difference of a minute region up to about 10 μm square. is there.

  As described above, the birefringence Δn of the optical compensation coating film 1 with respect to light having a wavelength of 548 nm preferably satisfies 0.001 ≦ Δn ≦ 0.35. That is, when the thickness of the convex portion 3 is dnm and the phase difference of the convex portion 3 is r (λ) nm, it is preferable that 0.001 ≦ r (λ) /d≦0.35. The thickness of the coating film 1 for optical compensation incorporated in an optical device such as a liquid crystal display device is generally 1 to 100 μm. When the optical compensation coating film 1 is used for optical compensation of a liquid crystal display device, a phase difference of 350 nm or less is generally suitable for optical compensation. Therefore, even if the coating film 1 for optical compensation is as thin as 1 μm, the birefringence Δn is preferably 0.35 or less in order to perform optical compensation. In addition, when the birefringence Δn is 0.001 or more, the use of the thick optical compensation coating film 1 such as 100 μm makes it possible to express a phase difference of 100 nm or more.

  Moreover, the shape of each recessed part 2 and the convex part 3 is not specifically limited, For example, each of the recessed part 2 and the convex part 3 is a rectangular shape, and even if it arrange | positions in stripe form by making a longitudinal direction parallel. Good. The optical compensation coating film 1 or the optical element 11 having such an arrangement is relatively easy to manufacture. Further, some of the plurality of unit regions may be elliptical or circular.

(About materials)
(Liquid crystal polymer)
In the present embodiment, the liquid crystalline polymer may be either a thermotropic type or a lyotropic type. Examples of such a liquid crystalline polymer include the following. That is, poly (γ-benzyl L-glutamate), Makromol. Chem. 179, 273-276 (1978), and liquid crystalline polymers such as polymethacrylate described in the same magazine. Among these, it is easy to obtain a large orientation birefringence when it is used as a coating film, that is, a liquid crystalline polymer that can be thinned to obtain a necessary phase difference, a cellulose derivative is preferable, and can be obtained at low cost. A cellulose derivative is more preferable. Among cellulose derivatives, ether-based derivatives of cellulose are preferable from the viewpoint of stability of physical properties such as low hydrolyzability and low hygroscopicity. Specifically, it is a compound in which at least one hydrogen atom of the hydroxyl group of cellulose is substituted with an alkyl group having 1 to 20 carbon atoms and / or a cyanoalkyl group having 1 to 20 carbon atoms. For example, methyl cellulose, Ethyl cellulose, propyl cellulose, butyl cellulose, pentyl cellulose, hexyl cellulose, heptyl cellulose, octyl cellulose, cyclopentyl cellulose, cyclohexyl cellulose, methyl ethyl cellulose, methyl propyl cellulose, methyl butyl cellulose, methyl pentyl cellulose, methyl hexyl cellulose, methyl heptyl cellulose, methyl Octylcellulose, methylcyclopentylcellulose, methylcyclohexylcellulose, ethylpropylcellulose, ethylbutylcellulose, Le Pen chill cellulose, ethylhexyl cellulose, ethyl heptyl cellulose, ethyl octyl cellulose, ethyl cyclopentyl cellulose, ethyl cyclohexyl cellulose, cyano methyl, cyano ethyl cellulose, and the like. These cellulose derivatives may be used alone or in combination of two or more.

  In addition, it is known that a cellulose derivative expresses liquid crystallinity (for example, Cellulose Society (ed.): Encyclopedia of Cellulose, 263-280, Asakura Shoten (2000)).

  Further, the lower limit of the number average molecular weight of the liquid crystalline polymer is preferably 5000, more preferably 8000, and still more preferably 10,000, and the upper limit is preferably 1000000, more preferably 500000, and further preferably 300000. When the number average molecular weight is less than 5,000, the strength of the coating film tends to decrease, and when the number average molecular weight is greater than 1,000,000, the workability tends to be inferior. The number average molecular weight is a value measured by gel permeation chromatography (GPC). In the present embodiment, two or more of the above-described polymers having different number average molecular weights may be used in combination, or may be used alone.

(solvent)
Next, a solvent for dissolving the liquid crystalline polymer used for forming the optical compensation coating film 1 according to this embodiment to form a coating solution will be described. The solvent is not particularly limited as long as the liquid crystalline polymer is soluble, but from the viewpoints of solubility, liquid crystallinity, etc., ether solvents, ketone solvents, halogenated hydrocarbon solvents, Carboxylic acid solvents are preferably used. Specific examples include ethyl ether, isopropyl ether, 1,3-dioxolane, 1,4-dioxane, tetrahydropyran, tetrahydrofuran, 1,2-dimethoxyethane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol. Ether solvents such as monopropyl ether and ethylene glycol monobutyl ether; ketone solvents such as acetone, 2-butanone, 4-methyl-2-pentanone and cyclohexanone; methylene chloride, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1,1,2-tetrachloroethane, 1,1,2,2-tetrachloroethane, pentachloroethane, hexachloroethane, 1-chloro Ropropane, 2-chloropropane, 1,1-dichloropropane, 1,2-dichloropropane, 1,3-dichloropropane, 2,2-dichloropropane, 1,2,3-trichloropropane, chlorobenzene, 1,2-di Halogenated hydrocarbon solvents such as chlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene Carboxylic acid solvents such as acetic acid, acrylic acid and methacrylic acid. Among these, from the viewpoint of drying of the film after coating, ethyl ether, isopropyl ether, 1,3-dioxolane, 1,4-dioxane, tetrahydropyran, tetrahydrofuran, 1,2-dimethoxyethane, acetone, 2-butanone 4-methyl-2-pentanone, cyclohexanone, methylene chloride, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane are preferably used. These solvents may be used alone or in combination of two or more.

  The amount of the solvent is preferably such that the ratio of the liquid crystalline polymer to the total weight of the liquid crystalline polymer and the solvent is in the range of 1% by weight at the lower limit and 70% by weight at the upper limit, and the lower limit is 2% by weight and the upper limit is 60%. % Is more preferable, and it is more preferable to use the lower limit of 3% by weight and the upper limit of 50% by weight. When the proportion of the liquid crystalline polymer is less than 1% by weight, the coating film thickness tends to be thin and the required film thickness tends to be difficult to obtain, and when it exceeds 70% by weight, the viscosity of the coating solution becomes too high. , Workability tends to be inferior.

(Additive)
Next, additives that can be added for the purpose of modifying the characteristics of the optical compensation coating film 1 of the present embodiment will be described. Additives include antioxidants (eg, hindered phenols such as IRGANOX 1010, IRGANOX 1135, IRGANOX 1330, etc. manufactured by Ciba Specialty Chemicals), processing stabilizers (eg, HP-136, IRGANOX manufactured by Ciba Specialty Chemicals). E201, IRGAFOS 168, etc.), light stabilizers (eg, hindered amines such as Sanol LS-765 and Sanol LS-770 manufactured by Sankyo Lifetech), ultraviolet absorbers (eg, TINUVIN P, TINUVIN 213 manufactured by Ciba Specialty Chemicals) Benzotriazoles such as TINUVIN 326), adhesion improvers (eg, silane cups such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane) ), Silanol condensation catalyst (for example, aluminum tris (ethyl acetoacetate) manufactured by Kawaken Fine Chemical, aluminum chelate M, etc.), plasticizer (for example, esters such as di-2-ethylhexyl phthalate, diisobutyl adipate) And surfactants (for example, fluorine compounds such as Fluorad FC-430 and Fluorad FC-4430 manufactured by Sumitomo 3M), antistatic agents (for example, IRGASTAT P18 and IRGASTAT P22 manufactured by Ciba Specialty Chemicals), and the like. These can be added as long as the objects and effects of the present invention are not impaired.

  The coating solution can be obtained, for example, by mixing the above-mentioned components at a temperature not lower than the melting point of the solvent and not higher than the boiling point, and after standing or stirring and mixing.

(substrate)
Next, the substrate 10 on which the optical compensation coating film 1 is formed on the surface will be described. As described above, the substrate 10 may be incorporated in an optical device such as a liquid crystal display device in a state where the optical compensation coating film 1 is applied. In such a case, the substrate 10 is preferably translucent. Various substrates can be used as the light-transmitting substrate 10. Specific examples of the compound include polycarbonate polymers; polyacrylates such as polymethyl acrylate and polymethyl methacrylate; adipine Condensation of dibasic acids such as acid, phthalic acid, isophthalic acid, terephthalic acid and 2,6-naphthalenedicarboxylic acid with glycols such as ethylene glycol, diethylene glycol, propylene glycol, tetramethylene glycol and neopentyl glycol, or the opening of lactones Polyester polymers obtained by ring polymerization; styrene polymers such as polystyrene and poly (α-methylstyrene); copolymers of acrylate and styrene; polyethylene, polypropylene, norbornene resins, cycloolefin polymers, poly Isoprene hydrogen Polyolefin polymers such as additives and hydrogenated polybutadiene; Cellulosic resins such as triacetyl cellulose and ethyl cellulose; Polyamides such as nylon 6 and nylon 66; Polyimide; Polyamide imide; Polyvinyl alcohol; Polyvinyl chloride; Polysulfone; Ether sulfone; polyarylate; epoxy resin; silicone resin; compounds described in International Publication No. 01/37007.

  In addition, these materials are formed by, for example, a solution casting method, a melt casting method, an extrusion method, a calendering method, and the like, and are contracted by using a non-stretching method, a uniaxial stretching method, a biaxial stretching method, or a shrinkable film. The light-transmitting substrate 10 can be stretched by a method (stretching in the thickness direction) or the like. On the other hand, a glass plate, a color filter, a liquid crystal cell or the like can be used as the light-transmitting substrate 10.

  As described above, the translucent substrate 10 used in the present embodiment is coated with a melt of a liquid crystalline polymer used for forming the optical compensation coating film 1 (either single-sided or double-sided coating). After forming the coating film, the optical element 11 in the laminated state may be incorporated in various optical devices as it is. In this case, the optical element 11 can be formed more easily. For example, a polarizing plate or the like having an optical compensation function, in which a light-transmitting substrate 10 itself is attached to a polarizer as a protective film, can be used.

  Alternatively, the optical compensation coating film 1 may be peeled off from the substrate 10 and the optical compensation coating film 1 itself may be incorporated into various optical devices. In this case, although it is inferior to the former in convenience at the time of manufacture, it is still excellent in convenience by using a transfer method or the like. In addition, since there is no concern that the solvent during coating damages the optical device, the selection range of the coating solution can be expanded.

(About wavelength dispersion of phase difference)
In the optical compensation coating film 1 of this embodiment, the entire optical compensation coating film 1 can be easily designed by appropriately designing the orientation degree of the liquid crystalline polymer to be used and the thicknesses of the concave portions 2 and the convex portions 3. The chromatic dispersion of the phase difference can be controlled. Therefore, how the wavelength dispersion of the entire retardation is determined in the optical compensation coating film 1 of the present embodiment will be described. The details of this principle are as described in the international application by the present inventors: PCT / JP2007 / 073246, and therefore will be described in a simplified manner.

  The coating film 1 for optical compensation of the present embodiment is composed of a plurality of concave portions 2 and convex portions 3 existing along a direction parallel to the surface of the substrate 10, and has a phase difference with respect to light having the same wavelength (here, 548 nm). Is different by 10 nm or more between the adjacent concave portion 2 and convex portion 3. And it utilizes that the wavelength dependence of the phase difference in each concave part 2 and each convex part 3 differs from the wavelength dependence of the synthetic phase difference R (λ) in the entire region including all the concave parts 2 and convex parts 3. Is.

  R (λ) is the phase difference of the convex portion 3 measured with light of wavelength λ (nm), and r ′ (λ) is the phase difference of the concave portion 2 measured with light of wavelength λ (nm), R (λ) is a combined phase difference in the film surface measured with light having a wavelength λ (nm). The phase difference described here is a phase difference when viewed from a direction perpendicular to the light incident surface (in this specification, “phase difference” means the light incident surface unless there is an angle with respect to the light incident surface). It means the phase difference when viewed from the direction perpendicular to. The composite phase difference is a phase difference when the entire region is viewed macroscopically. Furthermore, “use” means to use the wavelength dependence of the composite phase difference with the entire region as one element.

  At this time, the combined phase difference R (λ) indicates a phase difference corresponding to the average birefringence of the birefringence due to the phase difference between the concave portions 2 and the convex portions 3. Here, even if the phase difference is the same, different birefringence is exhibited if the wavelength of light incident thereon is different.

For example, as a characteristic quantity indicating birefringence, a film having a phase difference r _e (nm) between two polarizing plates in which the polarizing axes of the polarizing plates are parallel to each other (parallel Nicol state), and the slow axis thereof is Consider the transmittance I (θ, λ) at a wavelength λ (nm) when it is placed at an angle θ (rad) with the transmission axis of the polarizing plate. At this time, the transmittance is given by the following equation.

I (θ, λ) = cos ⁴ θ + sin ⁴ θ + 1/2 · cos (2πr _e / λ) · sin ² (2θ)
Here, when θ is π / 4 rad (= 45 °), the transmittance is given by the following equation and is represented by a trigonometric function.

I (π / 4, λ) = 1/2 + 1/2 · cos (2πr _e / λ)
However, the period differs depending on the wavelength. Even if the phase difference in each unit region has the same value regardless of the wavelength, the combined phase difference changes depending on the wavelength. On the contrary, even if the phase difference shows positive chromatic dispersion in each concave portion 2 and each convex portion 3, the combined phase difference may not change depending on the wavelength. In the present specification, “positive wavelength dispersion” is a long wavelength when the phase difference measured with light of a wavelength of 548 nm is 1 and the phase difference measured with light of another wavelength is expressed as its relative value. This means that the relative value becomes smaller. On the contrary, the case where the relative value becomes large is referred to as “reverse wavelength dispersion”.

  The wavelength dependence (wavelength dispersion) of the combined phase difference is determined by the difference in phase difference between the concave portion 2 and the convex portion 3 and the area ratio of the concave portion 2 and the convex portion 3 with respect to the entire region. The difference in phase difference between the concave portion 2 and the convex portion 3 depends on the difference in thickness.

For example, when a polymer film having rectangular irregularities on the surface is formed of the same material, the ten-point average roughness is measured at the convex part 3 of the film with Rz _JIS (μm), a contact-type film thickness meter, etc. When the average film thickness is d (μm), the birefringence of the concave portion 2 and the convex portion 3 is equivalent, so the ratio of the average magnitude of the phase difference of the unit region is expressed by the ratio of the thickness of each part. Is done. That is,
(D-Rz _JIS ) / d = 1-Rz _JIS / d
It becomes. Therefore, the ratio of the phase difference between the concave portion 2 and the convex portion 3 can be controlled by controlling Rz _JIS / d.

R (548) -R (447)> r (548) -r (447) Formula A
From the viewpoint of obtaining the relationship, the lower limit of Rz _JIS / d is preferably 0.05, more preferably 0.1, and even more preferably 0.15. If Rz _JIS / d is smaller than 0.05, the difference in phase difference between adjacent unit regions may not be sufficiently obtained, and the relationship of Formula A tends to be not obtained. The upper limit is not particularly limited as long as it is smaller than 1. In the case of Rz _JIS / d = 1, since there is no single film, the upper limit needs to be smaller than 1.

  From the above, the wavelength dispersion of the composite phase difference can be easily controlled without being restricted by the material.

  Further, since the chromatic dispersion of the combined phase difference in the entire region can be controlled by the phase difference and area ratio of each unit region, there is no restriction by the material. That is, the material can be selected so that properties other than wavelength dispersion, for example, various physical properties such as glass transition temperature and photoelastic coefficient, are intended.

  Thus, the present invention utilizes the wavelength dependence of the combined phase difference R (λ) viewed macroscopically with the entire region as one element.

Further, the optical compensation coating film 1 has a wavelength dependency of the synthetic retardation R (λ).
R (447) ≦ R (548) ≦ R (628)
It may satisfy.

  Thereby, the coating film 1 for optical compensation which shows reverse wavelength dispersion can be easily realized, and the degree of wavelength dispersion can also be controlled. In addition, a larger inverse chromatic dispersion can be easily realized as compared with the case where the chromatic dispersion is controlled by a conventional material.

  Further, the present invention is used as an optical compensation of a liquid crystal display device having high image quality such as a TN (Twisted Nematic) system, a VA (Vertical Alignment) system, an IPS (In-Plane Switching) system, an OCB (Optically Compensated Birefringence) system, and the like. When the coating film 1 or the optical element 11 is used, the phase difference generally needs to be 350 nm or less. Therefore, the combined phase difference R (548) is preferably 350 nm or less.

In addition,
R (548) -R (447)> r (548) -r (447)
From the viewpoint of obtaining the relationship, the difference in phase difference between the adjacent concave portion 2 and the convex portion 3 is preferably 10 nm as the lower limit, more preferably 50 nm as the lower limit, and even more preferably 100 nm as the lower limit.

  Furthermore, since it is preferable that the optical axes of the concave portions 2 and the convex portions 3 are in the same direction, the variation of the optical axes is preferably within ± 5 degrees, more preferably within ± 3 degrees, and further within ± 1 degrees. preferable.

(Application example)
Next, a display device to which the optical compensation coating film 1 can be applied will be described. Examples of the display device include an EL display and a liquid crystal display. Examples of the liquid crystal display include a liquid crystal display configured in the order of light source / light guide plate / light diffusion plate / prism sheet / brightness enhancement film / polarizing plate / liquid crystal cell / polarizing plate. By mounting the optical compensation coating film 1 or the optical element 11 of the present invention on the side and / or the outgoing light side, a display device with optical compensation can be obtained. Examples of the liquid crystal cell method include a TN method, a VA method, an IPS method, and an OCB method.

  The optical compensation coating film 1 or the optical element 11 of the present invention can be used for expanding the viewing angle of a liquid crystal display using a liquid crystal cell such as a TN system, a VA system, an IPS system, and an OCB system. The optical compensation coating film 1 or the optical element 11 can be suitably used for liquid crystal display device manufacturing parts such as a video, a camera, a mobile phone, a personal computer, a television, a monitor, and an automobile instrument panel.

  The optical compensation coating film 1 desirably has a plurality of concave portions 2 and convex portions 3 in a region corresponding to a display cell of a display device to which these are applied. Although the preferred size varies depending on the state of presence, for example, when the concave portion 2 and the convex portion 3 are present in stripes, the upper limit is preferably 100 μm, more preferably 50 μm, and even more preferably 20 μm. That is, when the display device is actually visually recognized, the unit regions need to be averaged, and the absolute size thereof is not limited depending on the device to which the unit region is applied. Here, the display cell indicates the minimum display unit (dot) of the display device. For example, when one color is formed by superimposing any of the colors of three primary color (RGB) color filters on one liquid crystal cell, the three color liquid crystal cells are combined to form a single pixel. Each liquid crystal cell of R, G, B is called a display cell. The display cell may be an EL cell.

  As described above, the optical compensation coating film 1 may be used in a state where it is peeled off from the substrate, or may be used together with the substrate without being peeled off from the substrate. In this case, the optical element 11 including the substrate 10 and the optical compensation coating film 1 can be incorporated into various display devices as it is.

(Production method)
Next, a method for manufacturing the optical compensation coating film 1 according to this embodiment will be described. The manufacturing method according to the present embodiment applies a solution or melt of a liquid crystalline polymer to the surface of the substrate while applying stress in a direction parallel to the surface of the substrate using an application member such as a bar or roll having irregularities. It is a solution casting method or a melt casting method in which an unevenness is formed on the film surface during coating as well as coating.

  FIG. 2 is a diagram showing an example of an application member used in the present manufacturing method. As shown in FIG. 2, a bar coater 20 in which a metal wire 22 is wound around a coating bar 21 can be used as an application member. The bar coater 20 is moved in a direction perpendicular to the axis of the coating bar 21 to apply the solution onto the substrate 10.

  FIG. 3 is an enlarged view of the bar coater. As shown in FIG. 3, the distance from the axis of the coating bar 21 is the boundary between adjacent metal wires 22 (described as “A” in the drawing) and the central portion of the metal wire 22 (shown as “B” in the drawing). It is different from the description. Therefore, when the bar coater 20 is moved, the thickness of the boundary portion (A portion in the figure) of the metal wire 22 in the liquid crystalline polymer solution or melt is the central portion (B portion in the drawing) of the metal wire 22. ) Becomes thicker. However, if the viscosity of the liquid crystalline polymer solution or melt is too low, the solution will move until it is dried, and the melt will move so as to be uniform before being cooled. . Therefore, the viscosity of the liquid crystal polymer solution or melt is set so that the thickness does not become uniform before drying or cooling.

  In the state after the bar coater 20 is moved by drying in a drying step described later or by cooling to a glass state, that is, in the solution or melt of the liquid crystalline polymer, The state where the thickness of the portion where the A portion has passed is maintained to be thicker than the portion where the B portion has passed. As a result, the portion through which the A portion of the bar coater 20 has passed becomes the convex portion 3, and the portion through which the B portion has passed becomes the concave portion 2. Thus, by applying using the bar coater 20, it is possible to easily form an uneven shape in which the concave portion 2 and the convex portion 3 are repeated on the surface of the optical compensation coating film 1.

  Moreover, when applying with the bar coater 20, it applies, applying a stress in the direction parallel to the surface of the board | substrate 10. FIG. Thereby, it can be made to orient in the direction which applied stress, or the direction substantially orthogonal to the direction, and an optical axis can be obtained in the orientation direction. That is, when the coating direction (bar coater moving direction) is a 0 degree direction and the counterclockwise direction is a positive angle, the orientation angle of the optical compensation coating film 1 is approximately 0 degrees (coating direction), approximately 90 degrees, or approximately −. A film of 90 degrees can be obtained, and the optical compensation coating film 1 having an optical axis in the direction can be obtained. From the viewpoint of facilitating the optical axis to be in the required relative positional relationship with other members in the apparatus, the orientation angle may be within a range of deflection within ± 5 degrees of the respective angles. Preferably, it is more preferably within the range of ± 3 degrees of deflection, and more preferably within the range of ± 1 degree of deflection. When such control is performed, when the other member is cut from a roll shape, for example, the optical axis of the optical compensation coating film 1 is set to the long side direction (MD Direction) or a short side direction (TD direction), and after pre-bonding with a roll-to-roll, it can be cut into a required size, and the manufacturing can be simplified, so the effect is great.

  In addition, in this way, the liquid crystalline polymer is oriented by applying it while applying stress to give the optical compensation coating film 1 birefringence. Therefore, it is not necessary to perform a stretching process, and the production can be simplified. Furthermore, since it is not necessary to perform a stretching process, the thicknesses of the concave portions 2 and the convex portions 3 on the surface of the optical compensation coating film 1 formed using the bar coater 20 are not changed by the stretching step. For this reason, control of the thickness of the recessed part 2 and the convex part 3 becomes easy.

  In order to easily apply stress to the solution or melt of the liquid crystal polymer, it is preferable to apply the solution or melt of the liquid crystal polymer a plurality of times. In this case, the solutions or melts penetrate each other at the interface with the previously applied liquid crystalline polymer solution or melt layer. As a result, a phenomenon appears as if it is adhered at the interface, and stress is easily generated in the coating direction. Thereby, the liquid crystalline polymer can be easily aligned.

  In the case where the liquid crystal polymer solution or melt is applied a plurality of times, the bar coater 20 may be used only for the last application, and an application member having a smooth surface may be used for the other application. This is because the surface of the optical compensation coating film 1 can be formed into an uneven shape by using the bar coater 20 only at the last coating.

  When the liquid crystalline polymer solution or melt is applied only once, the viscosity and shear rate (in this embodiment, related to the moving speed of the bar coater 20) may be increased. Thereby, the liquid crystalline polymer can be aligned even by a single application. In the case of coating only once, it is preferable to use a liquid crystalline polymer that easily exhibits liquid crystallinity.

  Then, after the solution casting, drying is performed. As this drying method, for example, a method in which a substrate coated with a liquid crystalline polymer solution is left (air dried) in an inert gas such as air or nitrogen, a method of heating and drying in a hot air oven, an infrared heating furnace, or the like, It can carry out by the method of drying under reduced pressure with a vacuum dryer etc., or combining these.

  As the drying temperature condition, either constant temperature or multistage temperature increase can be used. In the case of constant temperature, a temperature range of a lower limit of 10 ° C. and an upper limit of 200 ° C. is preferable, a lower limit of 15 ° C. and an upper limit of 180 ° C. are more preferable, and a lower limit of 20 ° C. and an upper limit of 160 ° C. are more preferable. When the drying temperature is lower than 10 ° C., the drying time tends to be longer, and when it is higher than 200 ° C., the coating film and the substrate tend to be thermally deteriorated. Although such constant temperature drying can be used, in order to dry effectively, it is preferable to raise the temperature in multiple stages, and from the economical viewpoint, primary drying and secondary drying are particularly preferable.

  When performing two-stage drying, the primary drying preferably has a temperature range of a lower limit of 10 ° C and an upper limit of 50 ° C, more preferably a lower limit of 15 ° C and an upper limit of 45 ° C, and even more preferably a lower limit of 20 ° C and an upper limit of 40 ° C. Primary drying is effective in suppressing foaming during secondary drying. When the primary drying temperature is lower than 10 ° C., the drying time required for suppressing foaming tends to be longer, and when it is higher than 50 ° C., foaming tends to occur easily.

  In secondary drying, a temperature range with a lower limit of 55 ° C. and an upper limit of 200 ° C. is preferred, a lower limit of 65 ° C. and an upper limit of 180 ° C. are more preferred, and a lower limit of 75 ° C. and an upper limit of 160 ° C. are more preferred. Secondary drying is effective to remove the solvent almost completely. If the secondary drying temperature is lower than 55 ° C, the drying time tends to be longer, and if it is higher than 200 ° C, thermal deterioration of the coating film or the substrate tends to occur.

  The unevenness on the surface of the optical compensation coating film 1 was viewed from a material having a relatively low phase difference (ideally 0 is preferable) relative to the phase difference of the film (that is, ideally perpendicular to the light incident surface). In this case, the surface of the optical compensation coating film 1 may be made uniform by filling with a material that does not exhibit birefringence: for example, a resin curable with ultraviolet rays or electron beams such as an acrylic resin. Thereby, scattering of light can be prevented.

  Other examples of such a low retardation material include the following unstretched polymers. Polycarbonate-based polymers; polyacrylic esters such as polymethyl acrylate and polymethyl methacrylate; dibasic acids such as adipic acid, phthalic acid, isophthalic acid, terephthalic acid, and 2,6-naphthalenedicarboxylic acid, ethylene glycol, and diethylene glycol Polyester polymers obtained by condensation with glycols such as propylene glycol, tetramethylene glycol and neopentyl glycol or ring-opening polymerization of lactones; styrene polymers such as polystyrene and poly (α-methylstyrene); acrylic acid Copolymer of ester and styrene; Polyolefin polymer such as polyethylene, polypropylene, norbornene resin, cycloolefin polymer, polyisoprene hydrogenated product, polybutadiene hydrogenated product; triacetyl cellulose Cellulose-based resins such as ethyl cellulose; polyamides such as nylon 6 and nylon 66; polyimides; polyamideimides; polyvinyl alcohol; polyvinyl chloride; polysulfone; polyethersulfone; polyarylate; Compounds described in the publication.

(Example according to this production method)
Examples are shown below to describe the present invention in more detail, but the present invention is not limited to these examples. First, a method for measuring various parameters will be described.

(1) Measurement of synthetic phase difference (R (447), R (548), R (628)) Using an automatic birefringence meter KOBRA-WR manufactured by Oji Scientific Instruments, light at a wavelength of 447 nm at a wavelength of 548 nm at 25 ° C. And light with a wavelength of 628 nm were measured under the condition of a spot of 5.8 mm square.

(2) Measurement of the orientation angle of the entire region Mounted on an automatic birefringence meter KOBRA-WR manufactured by Oji Scientific Instruments so that the direction of application of the liquid crystalline polymer solution is the 0 degree direction of the measuring device, and light with a wavelength of 590 nm Then, the orientation angle (angle formed by the 0 degree direction and the slow axis of the sample) was measured. In the case of a sample applied multiple times, the last application direction was set to 0 degree. The orientation angle is represented by a positive value for the counterclockwise angle from the 0 degree direction and a negative value for the clockwise angle.

(3) Measurement JIS ten point average roughness of the surface irregularities of the film _{(Rz JIS)} B0601: as measured in a vertical direction 2001 ten-point average roughness according to _{(Rz JIS)} with respect to the coating direction. In the case of a sample coated several times, measurement was performed in a direction perpendicular to the last coating direction.

(4) Measurement of phase difference between convex part and concave part of film Using a liquid crystal cell gap measuring device (TFM-120AFT-PC) using a micro polarized light spectrophotometer manufactured by Oak Manufacturing Co., Ltd., light having a wavelength of 447 nm under 25 ° C., Measurement with light having a wavelength of 548 nm was performed under the condition of a spot of 100 μm square. Note that r (447) and r (548) are phase differences with respect to light having a wavelength of 447 nm and a phase difference of 548 nm, respectively, at the convex portion 3 of the film, and r ′ (447) and r ′ (548) are respectively It is a phase difference for light having a wavelength of 447 nm and a phase difference of 548 nm in the concave portion 2 of the film. When measuring the phase difference of the convex part 3, it measured on the conditions that the center of a spot and the point with the thickest film thickness in the convex part 3 correspond. Moreover, when measuring the phase difference of the recessed part 2, it measured on the conditions that the center of a spot and the point with the thinnest film thickness in the recessed part 2 correspond. Moreover, the phase difference was measured about the convex part 3 located in the center vicinity of the coating film 1 for optical compensation, and the concave part 2 adjacent to the said convex part 3. FIG.

Example 1
40.0 g of methylene chloride was added to 10.0 g of ethyl cellulose (ETHOCEL STD type Premium FP grade, manufactured by Dow Chemical Co., Ltd., product number: 100, number average molecular weight: 63400, DS: 2.5) and dissolved at 25 ° C. This coating solution was designated as No. 7 Using a bar coater with a diameter of 180 μm, on a 150 μm thick glass substrate (average refractive index: 1.52, in-plane retardation: 0 nm), from the rear side to the front side of the glass substrate installation position After coating, the coating substrate was again applied again in the same direction to obtain a coated substrate composed of a glass substrate and a coating film. Thereafter, this coated substrate was dried in air at 25 ° C. for 5 minutes, and further dried in air at 100 ° C. for 5 minutes, thereby producing an optical element 11. The average film thickness (d (nm)) in the convex part 3 of the coating film 1 for optical compensation after drying is obtained by measuring the average thickness of the optical element 11 with a contact-type film thickness meter and subtracting the thickness of the glass substrate. Asked. Next, physical properties of the optical element 11 obtained as described above were measured. The results are shown in Table 1.

  In addition, number line No. 7 (a metal wire having a wire diameter of 180 μm) is used, the width of the concave portion 2 and the convex portion 3 is about 90 μm. Therefore, the measurement by the liquid crystal cell gap measuring device (TFM-120AFT-PC) performed under the condition of a spot of 100 μm square shows the phase difference between the concave portion 2 and the convex portion 3 almost accurately.

  In Table 1, R (447), R (548), and R (628) are combined phase differences of a region including a plurality of concave portions 2 and convex portions 3, and have a wavelength of 447 nm, a wavelength of 548 nm, and a wavelength of 628 nm, respectively. The phase difference with respect to light is shown. As described above, the composite phase difference is measured under the condition of a spot of 5.8 mm square. Moreover, the width | variety of the recessed part 2 and the convex part 3 is about 90 micrometers. Therefore, about 32 concave portions 2 and convex portions 3 are included in the spot. Therefore, the composite phase difference accurately indicates the phase difference when the plurality of concave portions 2 and convex portions 3 are viewed macroscopically. The same applies to Examples 2-8 below.

(Example 2)
The coating solution prepared in Example 1 was connected to the wire No. After applying from the back side to the front side from the position where the glass substrate was placed on a 150 μm thick glass substrate (average refractive index: 1.52, in-plane retardation: 0 nm) using a bar coater of No. 7, Application was repeated in the same direction, and then again applied again in the same direction to form a coated substrate. Thereafter, this coated substrate was dried in air at 25 ° C. for 5 minutes, and further dried in air at 100 ° C. for 5 minutes, thereby producing an optical element 11. The average film thickness (d (nm)) in the convex part 3 of the coating film 1 for optical compensation after drying is obtained by measuring the average thickness of the optical element 11 with a contact-type film thickness meter and subtracting the thickness of the glass substrate. Asked. Next, physical properties of the optical element 11 obtained as described above were measured. The results are shown in Table 1.

(Example 3)
The coating solution prepared in Example 1 was connected to the wire No. Using a 7 bar coater, instead of a glass substrate, apply to a 150 μm thick polyethylene naphthalate film parallel to the long side direction (MD direction) of the film, and then apply again in the same direction. A coated substrate was obtained. Thereafter, the coated substrate was dried in air at 25 ° C. for 5 minutes, and further dried in air at 100 ° C. for 5 minutes, and then the coating film 1 for optical compensation was peeled off from the polyethylene naphthalate film and used for optical compensation. The average film thickness (d (nm)) in the convex part 3 of the coating film 1 was measured with the contact-type film thickness meter. Next, physical properties were measured. The results are shown in Table 1.

Example 4
The coating solution prepared in Example 1 was connected to the wire No. After applying to the 150 μm thick polyethylene naphthalate film using the bar coater of No. 7 in the direction perpendicular to the long side direction (MD direction) of the film, that is, the short side direction (TD direction), and then again in the same direction. It was applied in layers to make a coated substrate. Thereafter, the coated substrate was dried in air at 25 ° C. for 5 minutes, and further dried in air at 100 ° C. for 5 minutes, and then the coating film 1 for optical compensation was peeled off from the polyethylene naphthalate film and used for optical compensation. The average film thickness (d (nm)) in the convex part 3 of the coating film 1 was measured with the contact-type film thickness meter. Next, physical properties were measured. The results are shown in Table 1. The orientation angle obtained here is almost the same as the result of Example 3, but the orientation of the polyethylene naphthalate film is different from that of Example 3 because the final coating direction is 90 degrees different from that of Example 3. This shows that the orientation direction of the optical compensation coating film 1 is substantially the same as the last coating direction without being affected by the surface shape or the like.

(Example 5)
The coating solution prepared in Example 1 was connected to the wire No. 7 was applied to a 150 μm thick polyethylene naphthalate film in parallel with the long side direction (MD direction) of the film to obtain a coated substrate. Thereafter, the coated substrate was dried in air at 25 ° C. for 5 minutes, and further dried in air at 100 ° C. for 5 minutes. Next, after coating again on this coated substrate in parallel with the long side direction (MD direction), it was dried in air at 25 ° C. for 5 minutes, and further dried in air at 100 ° C. for 5 minutes. Then, the coating film 1 for optical compensation was peeled off from the polyethylene naphthalate film, and the average film thickness (d (nm)) in the convex part 3 of the coating film 1 for optical compensation was measured with the contact-type film thickness meter. Next, physical properties were measured. The results are shown in Table 1.

(Example 6)
The coating solution prepared in Example 1 was connected to the wire No. 7 was applied to a 150 μm thick polyethylene naphthalate film in parallel with the long side direction (MD direction) of the film to obtain a coated substrate. Thereafter, the coated substrate was dried in air at 25 ° C. for 5 minutes, and further dried in air at 100 ° C. for 5 minutes. Next, the coating substrate is applied so as to be perpendicular to the long side direction (MD direction), that is, in the short side direction (TD direction), then dried in air at 25 ° C. for 5 minutes, and further at 100 ° C. After drying in the air for 5 minutes, the optical compensation coating film 1 is peeled off from the polyethylene naphthalate film, and the average film thickness (d (nm)) at the convex portion 3 of the optical compensation coating film 1 is measured by a contact-type film thickness meter. It was measured by. Next, physical properties were measured. The results are shown in Table 1. The orientation angle obtained here is almost the same as the result of Example 5, but the orientation is shifted by about 90 degrees from Example 5 because the final application direction is different by 90 degrees, and the application at the first application is performed. This shows that the orientation direction of the optical compensation coating film 1 is substantially the same as the last coating direction without being affected by the orientation of the film, the shape of the surface, and the like.

(Example 7)
The coating solution prepared in Example 1 was connected to the wire No. Using a 7 bar coater, a 60 μm thick cycloolefin polymer film (average refractive index: 1.53, in-plane retardation: 2 nm) was applied in parallel with the long side direction (MD direction) of the film, and coated substrate It was. Thereafter, the coated substrate was dried in air at 25 ° C. for 5 minutes, and further dried in air at 100 ° C. for 5 minutes. Next, this coating substrate is again applied in parallel with the long side direction (MD direction), dried in air at 25 ° C. for 5 minutes, and further dried in air at 100 ° C. for 5 minutes. The roll-shaped optical element 11 was produced by winding in the long side direction (MD direction). The average film thickness (d (nm)) and physical properties of the convex portion 3 of the optical compensation coating film 1 were measured in the same manner as described above after peeling from the cycloolefin polymer film. The results are shown in Table 1. From the measurement results, the alignment direction of the optical compensation coating film 1 was the long side direction (MD direction) of the winding roll.

(Example 8)
The coating solution prepared in Example 1 was connected to the wire No. Using a 7 bar coater, a 60 μm thick cycloolefin polymer film (average refractive index: 1.53, in-plane retardation: 2 nm) was applied in parallel with the long side direction (MD direction) of the film, and coated substrate It was. Thereafter, the coated substrate was dried in air at 25 ° C. for 5 minutes, and further dried in air at 100 ° C. for 5 minutes. Next, the coating substrate is applied in a direction perpendicular to the long side direction (MD direction), that is, in the short side direction (TD direction), dried in air at 25 ° C. for 5 minutes, and further at 100 ° C. for 5 minutes. After drying for a minute in the air, the roll-shaped optical element 11 was produced by winding in the long side direction (MD direction). The average film thickness (d (nm)) and physical properties of the convex portion 3 of the optical compensation coating film 1 were measured in the same manner as described above after peeling from the cycloolefin polymer film. The results are shown in Table 1. From the measurement results, the orientation direction of the coating film 1 for optical compensation was the short side direction (TD direction) of the winding roll.

(Comparative Example 1)
The coating solution prepared in Example 1 was coated on a 50 μm-thick polyethylene terephthalate film in parallel with the long side direction (MD direction) of the film using a stainless steel bar having a smooth surface of 8 mm in diameter. It was. Thereafter, the coated substrate was dried in air at 25 ° C. for 5 minutes, and further dried in air at 100 ° C. for 5 minutes. Next, after stretching in the long side direction 1.3 times at 150 ° C., the coating film was peeled off from the polyethylene terephthalate film, and the average film thickness (d (nm)) and physical properties of the coating film were measured. The results are shown in Table 1.

  As shown in Table 1, even when the coating is performed a plurality of times, it can be seen that the film is oriented in the coating direction when the last coating is performed. Further, in Example 1-8, both the phase difference r (λ) of the convex portion 3 and the phase difference r ′ (λ) of the concave portion 2 are greater with respect to light with a wavelength of 548 nm than with light with a wavelength of 447 nm. Greater than the value. That is, it shows positive chromatic dispersion. However, it was confirmed that the composite phase difference R (λ) was larger for the light with a wavelength of 548 nm than for the light with a wavelength of 447 nm, and showed reverse wavelength dispersion. On the other hand, in the comparative example, the thickness variation is small, and the chromatic dispersion in the entire region remains positive.

  As described above, this is because the concave portion 2 and the convex portion 3 which are regions having different thicknesses are provided, and the difference in phase difference between them is 10 nm or more, so that the total phase difference when the entire region is viewed macroscopically. However, it utilizes the fact that it can be made different from the wavelength dispersion of the phase difference of the respective regions of the concave portion 2 and the convex portion 3. And since the wavelength dispersion of the synthetic | combination phase difference of the whole area | region can be controlled with the phase difference and area ratio of each unit area | region, there is no restriction | limiting by a material.

(Other manufacturing methods)
An alignment film may be formed on the surface of the substrate, and a liquid crystalline polymer solution may be applied thereon. In this case, the liquid crystalline polymer can be easily aligned even if the stress in the direction parallel to the surface of the substrate is small. Even in this case, in order to form the concave portion 2 and the convex portion 3 on the surface of the optical compensation coating film 1, a method such as using a bar coater 20 having an uneven shape as the coating member is necessary.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The optical element of the present invention can be applied as a retardation film for a display device such as a liquid crystal display or an EL display.

It is a figure which shows an example of the coating film for optical compensation which concerns on one Embodiment of this invention, (a) is a perspective view, (b) is sectional drawing. It is a figure which shows an example of the application member used with the manufacturing method which concerns on this embodiment. FIG. 3 is an enlarged view of FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coating film for optical compensation 2 Concave part 3 Convex part 10 Substrate 20 Bar coater 21 Bar 22 for coating Metal wire

Claims (12)

A coating film for optical compensation formed by applying a liquid crystal polymer solution or melt on a substrate while being oriented in a direction parallel to the surface of the substrate,
The surface has a concavo-convex shape in which a concave portion and a convex portion are repeated,
The following formula (1) is satisfied, where r (nm) is a phase difference with respect to light having a wavelength of 548 nm in the convex portion, and r ′ (nm) is a phase difference with respect to light having a wavelength of 548 nm in the concave portion. Optical compensation coating film.
r−r ′ ≧ 10 Formula (1) 2. The optical compensation according to claim 1, wherein the following equation (2) is satisfied, where R (λ) is a combined phase difference with respect to light having a wavelength of λ nm in the entire region including all of the convex and concave portions. Coating film.
R (548) ≦ 350 nm Formula (2) Let r (λ) be the phase difference with respect to light having a wavelength λ nm at the convex portion, and let r ′ (λ) be the phase difference with respect to light with wavelength λ nm in the concave portion, and the wavelength λ nm in the entire region including all the convex portions and concave portions. 3. The coating film for optical compensation according to claim 1, wherein the following formulas (3), (4), and (5) are satisfied, where R (λ) is a combined phase difference with respect to light:
r (548) <r (447) Formula (3)
r ′ (548) <r ′ (447) Formula (4)
R (548) ≧ R (447) Formula (5) The following formula (6) is satisfied, where R (λ) is a combined phase difference with respect to light having a wavelength of λ nm in the entire region including all of the convex portions and concave portions. 2. The coating film for optical compensation according to item 1.
R (628) ≧ R (548) ≧ R (447) Formula (6)   The coating film for optical compensation according to any one of claims 1 to 4, wherein the liquid crystalline polymer is a cellulose derivative.   The cellulose derivative is a compound in which at least one hydrogen atom of a hydroxyl group of cellulose is substituted with an alkyl group having 1 to 20 carbon atoms and / or a cyanoalkyl group having 1 to 20 carbon atoms. Item 6. The coating film for optical compensation according to Item 5.   7. The coating film for optical compensation according to claim 5, wherein the cellulose derivative is at least one selected from methyl cellulose, ethyl cellulose, and cyanoethyl cellulose. A translucent substrate;
An optical element comprising: the optical compensation coating film according to claim 1, which is formed on the light-transmitting substrate. A method for producing an optical compensation coating film, wherein an optical compensation coating film is formed by a coating step of coating a liquid crystalline polymer solution or melt on a substrate,
In the application step,
While aligning the liquid crystalline polymer in a direction parallel to the surface of the substrate,
The surface of the coating film for optical compensation has a concavo-convex shape in which a concave portion and a convex portion are repeated, and a phase difference r (nm) with respect to light having a wavelength of 548 nm in the convex portion and a phase difference r ′ with respect to light with a wavelength of 548 nm in the concave portion. A method for producing a coating film for optical compensation, wherein the solution or melt of the liquid crystalline polymer is applied so that (nm) satisfies the following formula (1).
r−r ′ ≧ 10 Formula (1)   The liquid crystalline polymer is oriented in a direction parallel to the surface of the substrate by applying a solution or a melt of the liquid crystalline polymer by applying a stress in a direction parallel to the surface of the substrate. The manufacturing method of the coating film for optical compensation of Claim 9.   11. The method for producing a coating film for optical compensation according to claim 10, wherein the solution or melt of the liquid crystalline polymer is applied to the substrate in a plurality of times.   12. The surface of the coating film for optical compensation is formed into a concavo-convex shape by applying the liquid crystalline polymer solution or melt with a coating member having a concavo-convex surface. 2. A method for producing a coating film for optical compensation according to claim 1.

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