JP2006227222A - Coating film for optical compensation, coating liquid for forming coating film, optical element manufactured by using the coating liquid and manufacturing method of optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost coating film for optical compensation having a characteristic; [(n<SB>x</SB>+n<SB>y</SB>)/2-n<SB>z</SB>]×d≥100, without requiring a troublesome filming process, and to provide an optical element having the characteristic without requiring a labor such as film sticking. <P>SOLUTION: The coating film for optical compensation includes a cellulose derivative which satisfies the following relation; [(n<SB>x</SB>+n<SB>y</SB>)/2-n<SB>z</SB>]×d≥100, where n<SB>x</SB>is the maximum refractive index and n<SB>y</SB>is the minimum refractive index among in-plane refractive indexes, n<SB>z</SB>is refractive index in the thickness direction and d is film thickness (nm) when being thinned. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention uses an optical compensation coating film for optical compensation of retardation by a liquid crystal cell, an optical compensation coating film forming coating solution suitable for forming the coating film, and the coating liquid. The present invention relates to an optical element manufactured by the method and a method for manufacturing the optical element.

In a liquid crystal display device, a phase difference film for optical compensation is used in order to compensate for a phase difference due to birefringence of a liquid crystal cell and to expand a viewing angle. For example, polymer casting methods such as polycarbonate, polyester, polyamide, polyimide, polyethersulfone, solution casting method, uniaxial stretching method of dried product after solution casting, biaxial stretching method of dried product after solution casting, extrusion method, extruded product And a film formed by a biaxial stretching method, an extrudate biaxial stretching method, a calendar method, or the like (see, for example, Patent Document 1). Recently, a liquid crystal cell such as a VA (Vertical Alignment) type has been developed to expand the viewing angle, but an optical compensation material is necessary as in the past. To compensate for the phase difference due to birefringence of the VA type liquid crystal cell is an optical compensation material having characteristics of n _x ≧ n _y> n _z is known to be effective, since the use of the film Requires a cumbersome film forming process, and also requires time and effort such as sticking to liquid crystal display component parts. In order to solve these problems, polyimide paste coating has been proposed (see, for example, Patent Document 2). However, polyimide is problematic in that the synthesis is complicated and the material cost is high.
JP-A-3-33719 JP 2001-290023 A

An object of the present invention is to provide an optical compensation coating film having a large thickness retardation of [(n _x + _ny ) / 2− _nz ] × d ≧ 100 without requiring a complicated film forming step. And it is providing the optical element which has the characteristic, without requiring effort, such as film sticking.

Such problems present inventors to solve is the result of intense research, largest of the n _x of the in-plane refractive index of the time of thinning, the smallest ones and n _y, in the thickness direction refraction For optical compensation, comprising a cellulose derivative satisfying a relationship of [(n _x + _ny ) / 2−n _z ] × d ≧ 100 when the rate is n _z and the film thickness is d (nm) The present inventors have found that the above problems can be solved by using a coating film, and have reached the present invention.

That is, the present invention
Of the in-plane refractive indexes when the film is thinned, the maximum one is _nx , the minimum one is _ny , the refractive index in the thickness direction is _nz , and the film thickness is d (nm). _x + _ny ) / 2- _nz ] × d ≧ 100, a coating film for optical compensation characterized by containing a cellulose derivative satisfying the relationship:
2. The optical compensation coating film according to claim 1, wherein the cellulose derivative is a compound in which at least one of hydroxyl groups of cellulose is substituted with an alkoxy group having 1 to 20 carbon atoms (claim 2).
It is a coating solution for forming an optical compensation coating film formed by containing the following (A) and (B) (claim 3),
(A) The cellulose derivative according to claim 1 or claim 2 (B) A solvent in which the component (A) is soluble After the coating liquid for forming an optical compensation coating film according to claim 3 is applied to a substrate, It is a method for producing an optical element (Claims 4 and 5), wherein the coating film is annealed and exposed to the vapor of the component (B) as necessary,
An optical element (Claim 6) obtained by coating the substrate with the coating liquid for forming an optical compensation coating film according to claim 3, and drying the substrate.
An optical element (Claim 7) manufactured using the manufacturing method according to any one of Claims 4 and 5.

In addition, when the refractive index in the thickness direction is nz and the film thickness d is [(n _x + _ny ) / 2- _nz ] × d ≧ 100 is satisfied, and an optical compensation coating film is provided.

In the unstretched film formed by the solution casting method, nx is the maximum refractive index, ny is the minimum in-plane refractive index, nz is the refractive index in the thickness direction, and d is the film thickness [( _{n x + n y) / 2} -n z ] × to provide an optical compensation for coated film formed by containing a cellulose derivative satisfying the relationship d ≧ 100 (claim 9).

In the unstretched film formed by the solution casting method, nx is the maximum refractive index, ny is the minimum in-plane refractive index, nz is the refractive index in the thickness direction, and d is the film thickness [( _nx + _ny ) / 2- _nz ] × d ≧ 100 and a coating solution for forming an optical compensation coating film comprising a solvent capable of solubilizing the cellulose derivative. Item 10).

In the unstretched film formed by the solution casting method, nx is the maximum refractive index, ny is the minimum in-plane refractive index, nz is the refractive index in the thickness direction, and d is the film thickness [( _nx + _ny ) / 2- _nz ] × d ≧ 100 and a coating solution for forming an optical compensation coating film, which comprises a solvent capable of solubilizing the cellulose derivative, and applied to the substrate. In addition, the present invention provides a method for producing an optical element in which the cellulose derivative is annealed by being exposed to a vapor of a soluble solvent and then dried, as necessary (claims 11 and 12).

When the coating film for optical compensation of the present invention is used, the characteristic of [(n _x + _ny ) / 2−n _z ] × d ≧ 100 can be obtained without the need for complicated film forming steps and film sticking. The optical compensation layer can be obtained at a low cost, and an optical element can be manufactured, which is extremely useful industrially.

  Hereinafter, the present invention will be described in detail.

In the present invention when, largest of the n _x of the in-plane refractive index of the time of thinning, the smallest ones and n _y, the refractive index in the thickness direction n _z, where the film thickness as d (nm) , [(N _x + _ny ) / 2−n _z ] × d ≧ 100 or a non-stretched film formed by the solution casting method [(n _x + _ny ) / 2− _nz ] A cellulose derivative satisfying the relationship of xd ≧ 100 (hereinafter sometimes referred to as the component (A)), for example, by using cellulose obtained from various wood pulp, cotton linter, cotton lint, etc. as a raw material and chemically modifying Can be manufactured. For example, carboxylic acid ester derivatives such as cellulose formate, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose acetate propionate, cellulose butyrate, cellulose acetate butyrate, cellulose trifluoroacetate; cellulose sulfate, cellulose nitrate, cellulose phosphate And inorganic acid ester derivatives such as methyl cellulose, ethyl cellulose, propyl cellulose, butyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, cyanoethyl cellulose, carboxymethyl cellulose and the like.

  Of these, ether derivatives are preferred from the standpoint of physical properties such as low hydrolyzability and low hygroscopicity. More preferably, it is an ether derivative in which at least one hydroxyl group of cellulose is substituted with an alkoxy group having 1 to 20 carbon atoms, and more preferably, at least one of hydroxyl groups of cellulose is substituted with an alkoxy group having 1 to 10 carbon atoms. It is an ether derivative.

  Specific examples of the preferred component (A) include 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. , Methylpentylcellulose, methylhexylcellulose, methylheptylcellulose, methyloctylcellulose, methylcyclopentylcellulose, methylcyclohexylcellulose, ethylpropylcellulose, ethylbutylcellulose, ethylpentylcellulose, ethylhexylcellulose, ethylheptylcellulose, ethyloctylcellulose, ethylcyclopentyl cell Over scan, ethylcyclohexyl cellulose. These cellulose derivatives may be used alone or in combination of two or more.

  The ether derivative of cellulose can be produced, for example, by making alkali cellulose with sodium hydroxide or the like, adding an alkyl halide such as chlorinated alkyl, and stirring with heating. At this time, when two or more alkyl halides are used, an ether derivative substituted with two or more alkoxy groups can be obtained.

  Cellulose has three hydroxyl groups per glucose residue as its constituent unit, and the degree of substitution per glucose residue (hereinafter sometimes referred to as DS) is 3 at the maximum, but the lower limit of the degree of substitution Is preferably 0.1, more preferably 0.5, still more preferably 1, and the upper limit is preferably 3, more preferably 2.95, and even more preferably 2.9. When the degree of substitution is lower than 0.1, it tends to be difficult to dissolve in a solvent. In the present invention, two or more cellulose derivatives having different degrees of substitution may be used in combination, or may be used alone.

  Furthermore, the lower limit of the number average molecular weight of the component (A) is preferably 5000, more preferably 8000, still more preferably 10,000, and the upper limit is preferably 300,000, more preferably 250,000, and even more preferably 200000. When the number average molecular weight is less than 5,000, the coating film strength tends to decrease, and when the number average molecular weight is more than 300,000, the coating film strength tends to be difficult to dissolve. The number average molecular weight is a value measured by a gel permeation chromatography (GPC) method. In the present invention, two or more cellulose derivatives having different number average molecular weights may be used in combination, or may be used alone.

  Moreover, in this invention, the various cellulose derivative illustrated as (A) component may be used independently, and 2 or more types may be used together.

  Hereinafter, a coating solution for forming an optical compensation coating film (hereinafter sometimes simply referred to as a coating solution) will be described. The coating liquid is preferably formed containing (A) the cellulose derivative and (B) a solvent in which the component (A) is soluble.

  The solvent for the component (B) is not particularly limited as long as the component (A) is soluble. Specific examples include benzene, toluene, o-xylene, m-xylene, and p-xylene. Hydrocarbon solvents such as isomer mixtures of ethylbenzene, isopropylbenzene and diethylbenzene; methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, furfuryl alcohol, Alcohol solvents such as benzyl alcohol; ether solvents such as ethyl ether, isopropyl ether, 1,3-dioxolane, 1,4-dioxane, tetrahydropyran, tetrahydrofuran; acetone, 2-butanone, 4-methyl-2-pentanone, Ketone solvents such as cyclohexanone; methyl chloride , Chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,1,1,2-tetrachloroethane, 1,1,2,2-tetra Chloroethane, pentachloroethane, hexachloroethane, 1-chloropropane, 2-chloropropane, 1,1-dichloropropane, 1,2-dichloropropane, 1,3-dichloropropane, 2,2-dichloropropane, 1,2,3- Trichloropropane, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3,5- Halogen solvents such as trichlorobenzene; methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, vinegar Examples include ester solvents such as butyl acid; amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, and 1-methyl-2-pyrrolidinone. These solvents may be used alone or in combination of two or more.

  In the present invention, the amount of the solvent is preferably such that the ratio of the component (A) to the total weight of the components (A) and (B) is 1% by weight lower limit and 70% by weight upper limit, More preferably, the upper limit is 60% by weight, and the lower limit is 3% by weight and the upper limit is 50% by weight. When the proportion of the component (A) 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 is greater than 70% by weight, the viscosity of the coating liquid increases. , Workability tends to be inferior.

  Next, resins that can be added for the purpose of modifying the properties of the coating film of the present invention will be described. The resins that can be added include polycarbonate resin, acrylic resin, polyester resin, polystyrene resin, polyolefin resin, polyamide resin, polyimide resin, polyvinyl alcohol resin, polyvinyl acetal resin, polyethersulfone resin, polyarylate resin, epoxy. Resins, silicone resins, phenol resins, urethane resins and the like are exemplified, but these can be added within a range that does not impair the object and effect of the present invention.

  Next, additives that can be added for the purpose of modifying the properties of the coating film and coating solution of the present invention 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 compounds such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane) Pulling agent), silanol condensation catalyst (eg, aluminum tris (ethyl acetoacetate) manufactured by Kawaken Fine Chemicals, aluminum chelate M, etc.), plasticizer (eg, 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 liquid of the present invention 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, after standing, stirring and mixing.

  Next, the substrate for the optical element will be described. Various substrates can be used as the substrate, but it is preferable that the substrate is transparent particularly from the viewpoint of use. Specific examples include polycarbonate polymers produced by polycondensation from bisphenol A and carbonyl chloride; polyacrylic acid esters such as polymethyl acrylate and polymethyl methacrylate; adipic acid, phthalic acid, isophthalic acid, Polyester polymers obtained by condensation of dibasic acids such as terephthalic acid and glycols such as ethylene glycol, diethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, or ring-opening polymerization of lactones; polystyrene, poly (α- Styrene polymers such as methylstyrene); copolymers of acrylic acid ester and styrene; polyolefin polymers such as polyethylene, polynorbornene, hydrogenated polyisoprene, and hydrogenated polybutadiene; triacetyl cellulose Cellulose-based resins: polyamides such as nylon 6 and nylon 66; polyimides; polyamide-imides; polyvinyl alcohol; vinyl chloride; polyethersulfone; epoxy resins: silicone resins: compounds described in WO 01/37007 Polymer casting method, solution casting uniaxial stretching method, solution casting dried product biaxial stretching method, extrusion method, extruded product uniaxial stretching method, extruded product biaxial stretching method, calendar method And the like, films obtained by attaching these films to polarizing plates, glass plates, color filters, liquid crystal cells, and the like.

  Next, a method for manufacturing an optical element will be described. The optical element can be produced by coating the coating liquid of the present invention on one side or both sides of the substrate, followed by drying; or after coating, annealing and drying. As coating methods, gravure roll coating method, Mayer bar coating method, doctor blade coating method, reverse roll coating method, dip coating method, air knife coating method, calendar coating method, skies coating method, kiss coating method, bar coating method , Slot die coating method, spin coating method and the like.

  As a drying method, it can be carried out by leaving it in air or in an inert gas such as nitrogen (air drying), heat drying in a hot air oven, an infrared heating furnace or the like, or drying under reduced pressure in a vacuum dryer or the like. Although various drying temperatures can be set, a temperature range of a lower limit of −30 ° C. and an upper limit of 300 ° C. is preferable, a lower limit of 0 ° C. and an upper limit of 280 ° C. are more preferable, and a lower limit of 10 ° C. and an upper limit of 260 ° C. are more preferable. When the drying temperature is lower than −30 ° C., the drying time tends to be longer, and when it is higher than 300 ° C., the coating film and the substrate tend to be thermally deteriorated.

  Annealing is preferably performed for improving the leveling property of the coating film, stress relaxation, and the like, and is effective for, for example, reducing in-plane retardation and reducing in-plane retardation fluctuation. In the present invention, the annealing is preferably performed in the vapor of the component (B) with the coating film of the coating substrate facing up and left still horizontally. The temperature at the time of annealing can be variously set, but the lower limit is preferably −30 ° C. and the upper limit [(B) component boiling point (° C.)], and the lower limit is −15 ° C. and the upper limit [(B) component boiling point (° C.) −5 ° C.] is more preferable, and the lower limit is 0 ° C., and the upper limit [(B) component boiling point (° C.) − 10 ° C.] is more preferable. If the annealing temperature is lower than −30 ° C., the annealing time tends to be longer, and if the annealing temperature is higher than the boiling point (° C.) of the component (B), the coating film tends to flow out from the substrate. There is. The pressure at the time of annealing can also be set variously, and it can carry out under atmospheric pressure, pressurization, or pressure reduction, but atmospheric pressure is preferred at the point of workability.

  Next, the optical characteristics of the optical compensation coating film in the present invention will be described.

The coating film for optical compensation of the present invention preferably has a characteristic of [(n _x + _ny ) / 2− _nz ] × d ≧ 100. When the thickness of the optical compensation for coated film and d (nm), the in-plane retardation is represented by _{(n x -n y) × d} , the thickness retardation, _{[(n x + n y) /} 2- n _z ] × d, the in-plane retardation is preferably 0 nm lower limit and 100 nm upper limit, more preferably 0 nm lower limit and 80 nm upper limit, and still more preferably 0 nm lower limit and 60 nm upper limit. If the in-plane retardation is larger than 100 nm, it tends to be difficult to compensate for the retardation due to the birefringence of the liquid crystal cell. Moreover, the lower limit of the thickness retardation is preferably 1 nm and the upper limit of 1000 nm, more preferably the lower limit of 10 nm and the upper limit of 800 nm, and still more preferably the lower limit of 20 nm and the upper limit of 600 nm. If the thickness retardation is larger than 1000 nm, it tends to be difficult to compensate for the retardation due to the birefringence of the liquid crystal cell.

  Further, the optical compensation coating film of the present invention, the coating film forming coating liquid and the optical element produced using the coating liquid are used in video, camera, mobile phone, personal computer, TV, monitor, automobile, etc. It can be used suitably for liquid crystal display device manufacturing parts such as instrument panels.

  Examples are shown below to describe the present invention in more detail, but the present invention is not limited to these examples.

Example 1
80.0 g of chloroform was added to 20.0 g of ethyl cellulose (ETHOCEL STD-100 manufactured by Dow Chemical Co., Ltd., number average molecular weight: 63400, DS: 2.5) and dissolved at 25 ° C. Next, this coating solution was applied to a 150 μm-thick glass substrate (average refractive index: 1.52, in-plane retardation: 0 nm, thickness retardation: 1 nm) using a bar coater, and then 6 ° C. at 25 ° C. The optical element was produced by air-drying in air for a period of time. The coating thickness after drying (d (nm)) was determined by measuring the thickness of the entire optical element and subtracting the thickness of the glass substrate. Next, the physical properties of the optical element obtained as described above were measured by the following method, and the results are shown in Table 1. Here, _{[(n x + n y) /} 2-n z ] × d ≧ 100 (Note, n _x = was n _y) optical element was obtained.

(1) Refractive index _{(n x, n y, n} z) using the measured Oji Scientific Instruments Ltd. automatic birefringence meter KOBRA-21ADH of, the refractive index was measured at 590nm light under 25 ° C.. From the results obtained, it was determined plane retardation by _{(n x -n y) × d} . In addition, the thickness retardation was determined by [( _nx + _ny ) / 2- _nz ] × d.

(Example 2)
Using the coating solution prepared in Example 1, the pressure applied to the bar coater was reduced and applied to a 150 μm thick glass substrate (average refractive index: 1.52, in-plane retardation: 0 nm, thickness retardation: 1 nm). After the processing, it was air-dried at 25 ° C. for 6 hours to produce an optical element. The coating thickness after drying (d (nm)) was determined by measuring the thickness of the entire optical element and subtracting the thickness of the glass substrate. Next, the physical properties of the optical element obtained as described above were measured by the method described in Example 1, and the results are shown in Table 1. Here, _{[(n x + n y) /} 2-n z ] × d ≧ 100 (Note, n _x> was n _y) optical element was obtained.

(Example 3)
Using the coating solution prepared in Example 1, the pressure applied to the bar coater was reduced and applied to a 150 μm thick glass substrate (average refractive index: 1.52, in-plane retardation: 0 nm, thickness retardation: 1 nm). Then, the coated substrate was placed in a glass container filled with chloroform vapor at atmospheric pressure, sealed, and then annealed at 25 ° C. for 72 hours. Thereafter, the coated substrate was taken out and air-dried at 25 ° C. for 6 hours to produce an optical element. The coating thickness after drying (d (nm)) was determined by measuring the thickness of the entire optical element and subtracting the thickness of the glass substrate. Next, the physical properties of the optical element obtained as described above were measured by the method described in Example 1, and the results are shown in Table 1. In Example 2, the in-plane retardation also increased at the same time as the thickness retardation increased. However, here, the in-plane retardation is 0 nm, that is, the in-plane retardation is 0 nm, that is, [(n _{x + n y) / 2-} n z ] × d ≧ 100 (Incidentally, the optical element of the n _x = was n _y) is obtained, the presence or absence of annealing, there can be manufactured of different optical compensation layer characteristics It was.

Example 4
80.0 g of methylene chloride was added to 20.0 g of ethyl cellulose (ETHOCEL STD-100 manufactured by Dow Chemical Co., Ltd., number average molecular weight: 63400, DS: 2.5), and dissolved at 25 ° C. Next, this coating solution was applied to a 150 μm-thick glass substrate (average refractive index: 1.52, in-plane retardation: 0 nm, thickness retardation: 1 nm) using a bar coater, and then 6 ° C. at 25 ° C. The optical element was produced by air-drying in air for a period of time. The coating thickness after drying (d (nm)) was determined by measuring the thickness of the entire optical element and subtracting the thickness of the glass substrate. Next, the physical properties of the optical element obtained as described above were measured by the method described in Example 1, and the results are shown in Table 1. Here, _{[(n x + n y) /} 2-n z ] × d ≧ 100 (Note, n _x> was n _y) optical element was obtained.

(Comparative Example 1)
By attaching a commercially available triacetylcellulose film (= cellulose triacetate film) having a thickness of 40 μm to a glass substrate having a thickness of 150 μm (average refractive index: 1.52, in-plane retardation: 0 nm, thickness retardation: 1 nm) An optical element was produced. The results obtained measuring physical properties of the optical elements was carried out by the method described in Example 1, the in-plane retardation is 0 nm, the thickness retardation is 37 nm, _{[(n x + n y) /} 2-n z ] × d The relationship of ≧ 100 was not satisfied (the thickness retardation was low).

(Comparative Example 2)
By attaching a commercially available triacetyl cellulose film (= cellulose triacetate film) having a thickness of 80 μm to a glass substrate having a thickness of 150 μm (average refractive index: 1.52, in-plane retardation: 0 nm, thickness retardation: 1 nm). An optical element was produced. The physical properties of the obtained optical element were measured by the method described in Example 1. As a result, the in-plane retardation was 1 nm and the thickness retardation was 70 nm, and [(n _x + _ny ) / 2−n _z ] × d The relationship of ≧ 100 was not satisfied (the thickness retardation was low).

  In Comparative Examples 1 and 2, troublesome film forming steps (replaced by purchasing the film) and film pasting were required.

Claims (12)

Of the in-plane refractive indexes when the film is thinned, the maximum one is _nx , the minimum one is _ny , the refractive index in the thickness direction is _nz , and the film thickness is d (nm). _x + _ny ) / 2- _nz ] × d ≧ 100, a cellulose derivative satisfying the relationship:   2. The coating film for optical compensation according to claim 1, wherein the cellulose derivative is a compound in which at least one hydroxyl group of cellulose is substituted with an alkoxy group having 1 to 20 carbon atoms. A coating solution for forming an optical compensation coating film formed by containing the following (A) and (B).
(A) Cellulose derivative according to claim 1 or claim 2 (B) A solvent in which component (A) is soluble   A method for producing an optical element, wherein the optical compensation coating film-forming coating solution according to claim 3 is coated on a substrate and then dried.   A method for producing an optical element, comprising: coating a substrate with the coating solution for forming an optical compensation coating film according to claim 3; exposing the coating film to vapor of component (B); and further drying the coating film.   An optical element obtained by applying the coating solution for forming an optical compensation coating film according to claim 3 to a substrate and drying the substrate.   The optical element manufactured using the manufacturing method of any one of Claim 4 or Claim 5. When the refractive index in the thickness direction is nz and the film thickness is d, [(n _x + n _y ) / 2- _nz ] × d ≧ 100 is satisfied, A coating film for optical compensation. Nx the largest of the refractive index in the plane, the smallest ones ny, and the refractive index in the thickness direction nz, when the film thickness is d, the unstretched film was formed into a film by a solution casting method [(n _x + _Ny ) / 2- _nz ] × d ≧ 100, a coating film for optical compensation formed by containing a cellulose derivative satisfying the relationship. Nx the largest of the refractive index in the plane, the smallest ones ny, and the refractive index in the thickness direction nz, when the film thickness is d, the unstretched film was formed into a film by a solution casting method [(n _x + _Ny ) / 2- _nz ] × d ≧ 100, a coating solution for forming an optical compensation coating film, which comprises a cellulose derivative satisfying the relationship: and a solvent capable of dissolving the cellulose derivative. Nx the largest of the refractive index in the plane, the smallest ones ny, and the refractive index in the thickness direction nz, when the film thickness is d, the unstretched film was formed into a film by a solution casting method [(n _x + _Ny ) / 2- _nz ] × d ≧ 100 and a coating solution for forming an optical compensation coating film comprising a solvent capable of solubilizing the cellulose derivative is applied to the substrate. A method for producing an optical element to be dried.   The method for producing an optical element according to claim 11, further comprising an annealing step of exposing the cellulose derivative to a vapor of a soluble solvent.