JP2010097115A - Optical compensation film and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical compensation film made of a coating film having a large retardation in a film thickness direction by coating, low wavelength dependency of retardation and excellent mechanical characteristics such as elongation. <P>SOLUTION: In the optical compensation film to be the coating film comprising a maleimide resin and a plasticizer, when optional two axes orthogonal to each other in an in-plane of the coating film are defined as axis x and axis y and an out-of-plane direction is defined as axis z, and when a refractive index in an axis x direction, a refractive index in an axis y direction and a refractive index in an axis z direction are defined as nx, ny and nz, respectively, a relation of three dimensional refractive indices is specified to be nx≈ny>nz. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical compensation film excellent in optical characteristics such as wavelength dependency and mechanical characteristics such as elongation, and in particular, an optical compensation film for a liquid crystal display element having an optical compensation function even in an unstretched state after coating, and its production It is about the method.

  Liquid crystal displays are widely used as the most important display devices in the multimedia society, from mobile phones to computer monitors, notebook computers, and televisions. Many optical films are used in liquid crystal displays to improve display characteristics.

  In particular, the optical compensation film plays a major role in improving the contrast when viewed from the front or obliquely, compensating for the color tone, and the like. As a conventional optical compensation film, a stretched film of polycarbonate, cyclic polyolefin, or cellulose resin is used. However, these films have problems such as a need for a stretching process and difficulty in obtaining uniformity of retardation in the stretching process. In particular, in a large-area film, it becomes even more difficult to control the retardation produced by stretching.

  As a method for solving the problem due to stretching, studies have been made on an optical compensation film that exhibits an uncompensated optical compensation function by coating.

  Harris and Chen of Akron University have proposed an optical compensation film made of rigid rod-like polyimide, polyester, polyamide, poly (amide-imide), and poly (ester-imide) (see, for example, Patent Documents 1 and 2). Since these materials have spontaneous molecular orientation, they are characterized by developing a phase difference without undergoing a stretching process by coating.

  Furthermore, an optical compensation film made of polyimide with improved polyimide coating properties (solubility in a solvent) (see, for example, Patent Document 3), and a polarizing plate in which a protective film of a polarizing plate is coated with a discotic liquid crystal compound (for example, Patent Document 4) and the like have been proposed.

  Moreover, the stretched film (for example, refer patent document 5) which consists of a phenylmaleimide-isobutene copolymer is proposed.

US Pat. No. 5,344,916 Japanese National Patent Publication No. 10-508048 Japanese Patent Laid-Open No. 2005-070745 Japanese Patent No. 2565644 JP 2004-269842 A

  However, since the polymer used in the methods proposed in Patent Documents 1 to 3 is an aromatic polymer, the wavelength dependence of the retardation is large, and when used as an optical compensation film of a liquid crystal display element, image quality such as color shift is obtained. It had the subject of a fall.

  In addition, the method using the discotic liquid crystal compound proposed in Patent Document 4 not only has problems such as requiring uniform alignment of the liquid crystal compound, complicating the coating process, and large alignment unevenness. Since the liquid crystal compound is mainly composed of an aromatic compound, it also has a quality problem that the wavelength dependency of retardation is large.

  The stretched film obtained in Patent Document 5 does not develop a phase difference only by coating (nx = ny = nz).

  Therefore, the present invention aims to provide an optical compensation film having excellent optical characteristics. More specifically, the present invention exhibits an optical compensation function when applied, and the wavelength dependence of the phase difference. It is an object of the present invention to provide an optical compensation film that is small in size and excellent in optical properties such as elongation.

  As a result of intensive studies in view of the above problems, the present inventors have found that a coating film comprising a specific resin and a plasticizer has an optical compensation function, particularly a coating type optical compensation suitable for optical compensation for liquid crystal display elements. As a result, the present invention has been completed.

  That is, the present invention is a coating film composed of a maleimide resin and a plasticizer, and any two axes orthogonal in the plane of the coating film are x-axis and y-axis, and the out-of-plane direction is z-axis, Optical compensation characterized in that the three-dimensional refractive index relationship is nx≈ny> nz, where nx is the refractive index in the x-axis direction, ny is the refractive index in the y-axis direction, and nz is the refractive index in the z-axis direction. It relates to membranes.

  Hereinafter, the optical compensation film of the present invention will be described in detail.

  The optical compensation film of the present invention is a coating film composed of a maleimide resin and a plasticizer, and any two axes orthogonal in the plane of the coating film are defined as an x-axis and a y-axis, and an out-of-plane direction is a z-axis. 3 when the refractive index in the x-axis direction is nx, the refractive index in the y-axis direction is ny (when nx and ny are different, the smallest refractive index is nx), and the refractive index in the z-axis direction is nz. The optical compensation film has a dimensional refractive index relationship of nx≈ny> nz.

  Examples of the maleimide resin used in the optical compensation film of the present invention include N-substituted maleimide polymer resin, N-substituted maleimide-maleic anhydride copolymer resin, and the like, and N-substituted resin constituting the maleimide resin. Examples of maleimide residue units include N-substituted maleimide residue units represented by the following general formula (1).

（ここで、Ｒ_１は、炭素数１〜１８の直鎖状アルキル基，分岐状アルキル基，環状アルキル基、ハロゲン基、エーテル基、エステル基、アミド基を示す。）
一般式（１）で示されるＮ−置換マレイミド残基単位におけるＲ_１は、炭素数１〜１８の直鎖状アルキル基，分岐状アルキル基，環状アルキル基、ハロゲン基、エーテル基、エステル基、アミド基であり、炭素数１〜１８の直鎖状アルキル基としては、例えばメチル基、エチル基、クロロエチル基、メトキシエチル基、ｎ−プロピル基、ｎ−ブチル基、ｎ−ヘキシル基、ｎ−オクチル基、ｎ−ラウリル基等が挙げられ、炭素数１〜１８の分岐状アルキル基としては、例えばイソプロピル基、イソブチル基、ｓ−ブチル基、ｔ−ブチル基等が挙げられ、炭素数１〜１８の環状アルキル基としては、例えばシクロヘキシル基等が挙げられ、ハロゲン基としては、例えば塩素、臭素、フッ素、ヨウ素等が挙げられる。これらの１種又は２種以上が挙げられ、特に位相差量が大きく、溶剤への溶解性、機械的強度に優れる光学補償膜となることから、ｎ−ブチル基、イソブチル基、ｓ−ブチル基、ｔ−ブチル基、ｎ−ヘキシル基、ｎ−オクチル基が好ましい。

(Here, R ₁ represents a linear alkyl group having 1 to 18 carbon atoms, a branched alkyl group, a cyclic alkyl group, a halogen group, an ether group, an ester group, or an amide group.)
R ₁ in the N-substituted maleimide residue unit represented by the general formula (1) is a linear alkyl group having 1 to 18 carbon atoms, a branched alkyl group, a cyclic alkyl group, a halogen group, an ether group, an ester group, Examples of the linear alkyl group having 1 to 18 carbon atoms that is an amide group include, for example, methyl group, ethyl group, chloroethyl group, methoxyethyl group, n-propyl group, n-butyl group, n-hexyl group, n- An octyl group, n-lauryl group, etc. are mentioned, As a C1-C18 branched alkyl group, an isopropyl group, an isobutyl group, s-butyl group, t-butyl group etc. are mentioned, for example, C1-C1 Examples of the 18 cyclic alkyl group include a cyclohexyl group, and examples of the halogen group include chlorine, bromine, fluorine, iodine and the like. One or more of these may be mentioned, and since the optical compensation film has a particularly large retardation amount and is excellent in solubility in a solvent and mechanical strength, n-butyl group, isobutyl group, s-butyl group , T-butyl group, n-hexyl group and n-octyl group are preferable.

  Specific examples of the N-substituted maleimide residue unit include, for example, an N-methylmaleimide residue unit, an N-ethylmaleimide residue unit, an N-chloroethylmaleimide residue unit, an N-methoxyethylmaleimide residue unit, Nn-propylmaleimide residue unit, N-isopropylmaleimide residue unit, Nn-butylmaleimide residue unit, N-isobutylmaleimide residue unit, Ns-butylmaleimide residue unit, Nt- 1 type or 2 types, such as a butyl maleimide residue unit, a Nn-hexyl maleimide residue unit, a N-cyclohexyl maleimide residue unit, a Nn-octyl maleimide residue unit, a Nn-lauryl maleimide residue unit In particular, since the optical compensation film has a large amount of retardation, excellent solubility in solvents, and mechanical strength, Nn-B Rumaleimide residue unit, N-isobutylmaleimide residue unit, Ns-butylmaleimide residue unit, Nt-butylmaleimide residue unit, Nn-hexylmaleimide residue unit, Nn-octylmaleimide residue Base units are preferred.

  Examples of the N-substituted maleimide polymer resin include N-methylmaleimide polymer resin, N-ethylmaleimide polymer resin, N-chloroethylmaleimide polymer resin, N-methoxyethylmaleimide polymer resin, Nn- Propylmaleimide polymer resin, N-isopropylmaleimide polymer resin, Nn-butylmaleimide polymer resin, N-isobutylmaleimide polymer resin, Ns-butylmaleimide polymer resin, Nt-butylmaleimide polymer Examples thereof include resin, Nn-hexylmaleimide polymer resin, N-cyclohexylmaleimide polymer resin, Nn-octylmaleimide polymer resin, and Nn-laurylmaleimide polymer resin.

  Examples of the N-substituted maleimide-maleic anhydride copolymer resin include N-methylmaleimide-maleic anhydride copolymer resin, N-ethylmaleimide-maleic anhydride copolymer resin, and N-chloroethylmaleimide-anhydride. Maleic acid copolymer resin, N-methoxyethylmaleimide-maleic anhydride copolymer resin, Nn-propylmaleimide-maleic anhydride copolymer resin, N-isopropylmaleimide-maleic anhydride copolymer resin, N -N-butylmaleimide-maleic anhydride copolymer resin, N-isobutylmaleimide-maleic anhydride copolymer resin, Ns-butylmaleimide-maleic anhydride copolymer resin, Nt-butylmaleimide-anhydrous Maleic acid copolymer resin, Nn-hexylmaleimide-maleic anhydride copolymer resin, N- Black hexyl maleimide - maleic anhydride copolymer resin, N-n-octyl maleimide - maleic anhydride copolymer resin, N-n-lauryl maleimide - can be mentioned maleic anhydride copolymer resin.

  Among them, the Nn-butylmaleimide polymer resin, the Nn-butylmaleimide polymer resin, and the Nn-butylmaleimide polymer resin, which are particularly excellent in film forming properties during film formation and become an optical compensation film excellent in optical compensation function and heat resistance, Nn-octylmaleimide polymer resin and Nn-octylmaleimide-maleic anhydride copolymer resin are preferable.

  Further, the maleimide resin constituting the optical compensation film of the present invention contains a residue unit other than the N-substituted maleimide residue unit and the maleic anhydride residue unit without departing from the object of the present invention. The residue unit may be, for example, a styrene residue unit such as a styrene residue unit or an α-methylstyrene residue unit; an acrylic acid residue unit; a methyl acrylate residue unit, or an ethyl acrylate residue. Units, acrylate residue units such as butyl acrylate residue units; methacrylic acid residue units; methacrylic acid ester residues such as methyl methacrylate residue units, ethyl methacrylate residue units, butyl methacrylate residue units Unit: vinyl ester residue such as vinyl acetate residue and vinyl propionate residue; acrylonitrile residue; one or two of methacrylonitrile residue It can be mentioned more.

Moreover, as this maleimide-type resin, the number average molecular weight (Mn) of standard polystyrene conversion obtained from the elution curve measured by gel permeation chromatography (henceforth GPC) is 1 * 10 < ³ > or more. In particular, it is preferably 2 × 10 ⁴ or more and 2 × 10 ⁵ or less because it becomes an optical compensation film having excellent mechanical properties and excellent moldability during film formation.

  The maleimide resin constituting the optical compensation film of the present invention may be produced by any method as long as the maleimide resin is obtained. For example, N-substituted maleimides, maleic anhydride, and in some cases It can be produced by performing radical polymerization or radical copolymerization using a monomer copolymerizable with N-substituted maleimides. Examples of N-substituted maleimides include N-methylmaleimide, N-ethylmaleimide, N-chloroethylmaleimide, N-methoxyethylmaleimide, Nn-propylmaleimide, N-isopropylmaleimide, Nn- 1 such as butylmaleimide, N-isobutylmaleimide, Ns-butylmaleimide, Nt-butylmaleimide, Nn-hexylmaleimide, N-cyclohexylmaleimide, Nn-octylmaleimide, Nn-laurylmaleimide Examples of the copolymerizable monomer include styrenes such as styrene and α-methylstyrene; acrylic acid; acrylic esters such as methyl acrylate, ethyl acrylate, and butyl acrylate. Methacrylic acid; methyl methacrylate, methacrylate Methacrylic acid esters such as butyl methacrylate, vinyl acetate, vinyl propionate, vinyl pivalate, vinyl laurate, vinyl stearate, etc .; acrylonitrile; one or more of methacrylonitrile, etc. Can be mentioned.

  Further, as the radical polymerization method, it can be carried out by a known polymerization method, and for example, any of a bulk polymerization method, a solution polymerization method, a suspension polymerization method, a precipitation polymerization method, an emulsion polymerization method and the like can be adopted. .

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

  And there is no restriction | limiting in particular as a solvent which can be used in a solution polymerization method, a suspension polymerization method, a precipitation polymerization method, and an emulsion polymerization method, For example, aromatic solvents, such as benzene, toluene, xylene; Methanol, ethanol, propyl alcohol, butyl alcohol Alcohol solvents such as cyclohexane, dioxane, tetrahydrofuran (THF), acetone, methyl ethyl ketone, dimethylformamide, isopropyl acetate, water, N-methylpyrrolidone, and the like, and mixed solvents thereof.

  Moreover, the polymerization temperature at the time of performing radical polymerization can be suitably set according to the decomposition temperature of a polymerization initiator, and generally it is preferable to carry out in the range of 40-150 degreeC.

  The plasticizer used in the optical compensation film of the present invention is not particularly limited. For example, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dihexyl phthalate, dinormal octyl phthalate, 2-ethylhexyl phthalate, diisooctyl phthalate, dicapryl phthalate, dicap Nonyl phthalate, diisononyl phthalate, didecyl phthalate, diisodecyl phthalate, diundecyl phthalate, dilauryl phthalate, ditridecyl phthalate, dibenzyl phthalate, dicyclohexyl phthalate, butyl benzyl phthalate, octyl decyl phthalate, butyl octyl phthalate, octyl benzyl phthalate, normal hexyl Normal decyl phthalate, normal octyl normal decyl phthalate, di-2-ethyl Phthalate plasticizers such as xylisophthalate and di-2-ethylhexyl terephthalate; tricresyl phosphate, tri (2-ethylhexyl phosphate), trixylenyl phosphate, bisphenol A bis (diphenyl phosphate), triphenyl phosphate, 2 -Phosphate plasticizers such as ethylhexyl diphenyl phosphate, cresyl diphenyl phosphate, tricresyl phosphate, trimethyl phosphate, triethyl phosphate, tributyl phosphate, tris (butoxyethyl) phosphate; di-2-ethylhexyl adipate, diisodecyl adipate, normal Octyl-normal decyl adipate, normal heptyl-normal nonyl adipate, diisooctyl adipate, Adipate plasticizers such as iso-normal octyl adipate, di-normal octyl adipate, didecyl adipate; sebatate esters such as dibutyl sebacate, di-2-ethylhexyl sebacate, diisooctyl sebacate, butylbenzyl sebacate Plasticizer: azelaic acid ester plasticizer such as di-2-ethylhexyl azelate, dihexyl azelate, diisooctyl azelate; triethyl citrate, acetyl triethyl citrate, tributyl citrate, acetyl tributyl citrate, acetyl citrate Citric acid ester plasticizers such as tri (2-ethylhexyl); Glycolic acid ester plasticizers such as methyl phthalyl ethyl glycolate, ethyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate; Trimellitic acid such as tributyl trimellitate, tri-normal hexyl trimellitate, tri (2-ethylhexyl) trimellitate, tri-normal octyl trimellitate, tri-isoctyl trimellitate, tri-isodecyl trimellitate Ester plasticizers: tri (2-ethylhexyl) pyromellitate, tetrabutyl pyromellitate, tetra-normal hexyl pyromellitate, tetra (2-ethylhexyl) pyromellitate, tetra-normal octyl pyromellitate, tetra-isooctyl pyromellitate , Pyromellitic acid ester plasticizers such as tetra-isodecyl pyromellitate; ricinoleic acid ester plasticizers such as methyl acetyl ricinolate and butyl acetyl ricinolate; polypropylene adipate, polypropylene Polyester plasticizers such as bacates and their modified polyesters; epoxy plasticizers such as epoxidized soybean oil, epoxybutyl stearate, epoxy (2-ethylhexyl) stearate, epoxidized linseed oil, 2-ethylhexyl epoxy torate And acetate ester plasticizers such as glyceryl triacetate and 2-ethylhexyl acetate. Among these, phosphate ester plasticizers from the viewpoint of compatibility with maleimide resins, heat resistance and surface properties of the resulting optical compensation film, etc. Agents, trimellitic acid ester plasticizers, pyromellitic acid ester plasticizers are preferably used, and from the viewpoint of compatibility with maleimide resins, phosphoric acid ester plasticizers are particularly preferable, especially tricresyl phosphate, Tri (2-ethylhexyl) phosph Chromatography, trixylenyl phosphate, bisphenol A bis (diphenyl phosphate), tri-butyl trimellitate, tri (2-ethylhexyl) trimellitate, tri (2-ethylhexyl) pyromellitate are preferred. These may be used alone or in combination of two or more as required.

  The blending ratio of the maleimide resin and the plasticizer in the optical compensation film of the present invention is such that an optical compensation film having excellent mechanical properties such as film elongation can be obtained. The amount is preferably 1 to 40 parts by weight, more preferably 1 to 20 parts by weight, and particularly preferably 3 to 10 parts by weight.

  Moreover, there is no restriction | limiting in particular as a compounding method of a maleimide-type resin and a plasticizer, For example, it can carry out by adding a plasticizer to the solution which melt | dissolved the maleimide-type resin in the soluble solvent. In this case, the soluble solvent of the maleimide resin is not particularly limited, and examples thereof include benzene, toluene, xylene, ethylbenzene, cumene, chlorobenzene and the like as aromatic solvents; acetone, methyl ethyl ketone, methyl isobutyl ketone, non-aromatic solvents, Examples thereof include ketone solvents such as diisopropyl ketone and diisobutyl ketone, ester solvents such as methyl acetate, ethyl acetate, isopropyl acetate, butyl acetate and isobutyl acetate, ether solvents such as tetrahydrofuran, dioxane and 1,3-dioxolane. Among these solvents, a mixture of an aromatic solvent and a non-aromatic solvent is preferable, and a mixture of toluene and methyl ethyl ketone is particularly preferable.

  The optical compensation film of the present invention is a coating film composed of the maleimide resin and a plasticizer, and particularly has an excellent optical compensation function when used as an optical compensation film. When a film made of a polymer is used as an optical compensation film, the three-dimensional refractive index of the film is generally controlled by stretching the film. However, the stretching process may complicate the manufacturing process and quality control. There is a problem such as. On the other hand, the optical compensation film of the present invention is a coating film composed of a maleimide resin and a plasticizer, and any two axes orthogonal in the plane of the coating film are x-axis and y-axis, and the out-of-plane direction. Is the z-axis, the refractive index in the x-axis direction is nx, the refractive index in the y-axis direction is ny (if nx and ny are different, the smallest refractive index is nx), and the refractive index in the z-axis direction is nz. The optical compensation film is characterized in that the relationship of the three-dimensional refractive index at the time is nx≈ny> nz, and has been found to exhibit a unique behavior in which the refractive index in the thickness direction of the film becomes small without being stretched. .

Further, the out-of-plane retardation amount (Rth) of the optical compensation film of the present invention can be easily controlled by the thickness of the coating film composed of the maleimide resin and the plasticizer, and can be used as a retardation film. Therefore, the out-of-plane retardation (Rth) represented by the following formula (2) when measured with light having a measurement wavelength of 589 nm is preferably in the range of 30 to 2000 nm. The thickness is preferably from 50 to 1000 nm, and particularly preferably from 80 to 500 nm because the optical compensation film is excellent in the viewing angle improvement effect of the liquid crystal display element.
Rth = ((nx + ny) / 2−nz) × d (2)
(Here, d represents the film thickness (nm) of the optical compensation film.)
Since the optical compensation film of the present invention is a liquid crystal display element having a small color shift when used in a liquid crystal display element, it is preferable that the wavelength dependence of the phase difference amount is small. The wavelength dependency (R450 / R589) of the phase difference amount indicated by the ratio of the phase difference amount (R450) measured with light having a measurement wavelength of 450 nm and the phase difference amount (R589) measured with light having a measurement wavelength of 589 nm is 1 .1 or less is preferable, and 1.08 or less is particularly preferable.

  Since the optical compensation film of the present invention has good image quality characteristics when used in a liquid crystal display element, the optical transmittance of the optical compensation film measured according to JIS K 7361-1 (1997 edition) is high. It is preferably 85% or more, and particularly preferably 90% or more. Further, the haze (haze) of the optical compensation film measured in accordance with JIS K 7136 (2000 version) is preferably 2% or less, and particularly preferably 1% or less.

  The optical compensation film of the present invention is excellent in mechanical properties such as elongation. Specifically, the maximum point elongation is preferably 3 to 25%, particularly 5 to 20%. preferable. Further, the maximum point stress is preferably 30 to 200 MPa, and particularly preferably 40 to 160 MPa.

  The optical compensation film of the present invention preferably has high heat resistance from the stability of quality when used in a liquid crystal display element, and preferably has a glass transition temperature of 100 ° C. or higher, particularly 120 ° C. or higher. Some are preferred, and those having a temperature of 135 ° C. or higher are preferred.

  The optical compensation film of the present invention is characterized by comprising a coating film comprising a maleimide resin and a plasticizer. As a preferred production method, a glass substrate; a film such as triacetyl cellulose or polyethylene terephthalate (PET); Examples of the maleimide resin include a maleimide resin comprising a maleimide residue unit represented by the general formula (1). A resin is preferred. The coating method is a method in which a solution obtained by dissolving a maleimide resin and a plasticizer in a solvent is coated on a glass substrate or film, and then the solvent is removed by heating or the like. Examples of the coating method used here include a doctor blade method, a bar coater method, a gravure coater method, a slot die coater method, a lip coater method, and a comma coater method. In industry, the gravure coater method is generally used for thin film coating, and the comma coater method is generally used for thick film coating. There are no particular restrictions on the solvent used, for example, aromatic solvents such as toluene, xylene, chlorobenzene, nitrobenzene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone; dimethyl ether, diethyl ether, methyl-t-butyl ether Ether solvents such as tetrahydrofuran, dioxane, etc .; acetate solvents such as methyl acetate, ethyl acetate, acetic acid-n-propyl, isopropyl acetate, butyl acetate; chlorine systems such as carbon tetrachloride, chloroform, methylene chloride, dichloroethane, trichloroethane, etc. Solvents; Amide solvents such as dimethylformamide and dimethylacetamide; N-methylpyrrolidone and the like can be mentioned, and these can be used in combination of two or more. In solution coating, since an optical compensation film having higher transparency and excellent thickness accuracy and surface smoothness can be obtained, the solution viscosity is preferably 10 to 10000 cps, particularly 10 to 5000 cps. It is preferable to

  In this case, the coating thickness of the film composed of the maleimide resin and the plasticizer is determined by the amount of retardation in the thickness direction of the coating film, and among them, an optical compensation film having excellent surface smoothness and viewing angle improving effect is obtained. Since it is obtained, it is preferably 1 to 200 μm after drying, more preferably 5 to 100 μm, and particularly preferably 10 to 50 μm.

  The optical compensation film of the present invention can be used after being peeled off from the base material, and can also be used as a laminate with the base material.

  The optical compensation film of the present invention can be used by being laminated with a polarizing plate.

  Further, the optical compensation film of the present invention may contain an antioxidant in order to improve the thermal stability. Examples of the antioxidant include hindered phenol antioxidants, phosphorus antioxidants, and other antioxidants. These antioxidants may be used alone or in combination. And since an antioxidant effect | action improves synergistically, it is preferable to use together and use a hindered phenolic antioxidant and phosphorus antioxidant, for example, 100 weight part of hindered phenolic antioxidants in that case It is particularly preferable to use a phosphorous antioxidant mixed in an amount of 100 to 500 parts by weight. Further, the addition amount of the antioxidant is preferably 0.01 to 10 parts by weight, particularly in the range of 0.5 to 1 part by weight with respect to 100 parts by weight of the maleimide resin constituting the optical compensation film of the present invention. Preferably there is.

  Furthermore, as an ultraviolet absorber, for example, an ultraviolet absorber such as benzotriazole, benzophenone, triazine, or benzoate may be blended as necessary.

  The optical compensation film of the present invention includes other polymers, surfactants, polymer electrolytes, conductive complexes, inorganic fillers, pigments, dyes, antistatic agents, antiblocking agents, lubricants and the like within the scope of the invention. It may be blended.

  The optical compensation film of the present invention comprises a maleimide resin that exhibits an optical compensation function only by coating, and a plasticizer. Since the control of the optical compensation function is easy, a liquid crystal display element, particularly VA- It is useful as an optical compensation film effective for improving the contrast and viewing angle characteristics of a liquid crystal television in a mode.

  EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

-Measurement of number average molecular weight (Mn) and weight average molecular weight (Mw)-
Using gel permeation chromatography (GPC) (manufactured by Tosoh Corporation, trade name HLC-802A), dimethylformamide was used as a solvent to obtain a standard polystyrene equivalent value.

~ Measurement of glass transition temperature ~
A differential scanning calorimeter (manufactured by Seiko Denshi Kogyo Co., Ltd., trade name DSC2000) was used and the temperature was 10 ° C./min. It measured at the temperature increase rate of.

~ Measurement of light transmittance ~
As an evaluation of transparency, light transmittance was measured in accordance with JIS K 7361-1 (1997 edition).

~ Measurement of haze ~
As an evaluation of transparency, haze was measured according to JIS K 7136 (2000 version).

~ Measurement of refractive index ~
It measured using the Abbe refractometer (product made from Atago) based on JISK7142 (1981 edition).

~ Calculation of 3D refractive index ~
Using a sample tilt type automatic birefringence meter (trade name KOBRA-WR, manufactured by Oji Scientific Instruments Co., Ltd.), the elevation angle was changed and the three-dimensional refractive index was measured with light having a measurement wavelength of 589 nm. Further, the out-of-plane retardation (Rth) was calculated from the three-dimensional refractive index.

  The wavelength dependence (R450 / R589) of the retardation amount is determined by tilting the coating film by 40 degrees and measuring the retardation amount (R450) measured with light having a measurement wavelength of 450 nm and the retardation amount measured with light having a measurement wavelength of 589 nm (R589). ) Ratio.

~ Measurement of film strength ~
A test piece punched out to 10 mm × 100 mm (SSK1874-1) was pulled at a speed of 5 mm / min with a Tensilon type tensile tester (product name: UTM-2.5T, manufactured by Orientec Co., Ltd.). The point stress was determined.

Synthesis Example 1 (Example of production of Nn-butylmaleimide polymer resin)
A glass sealed tube was charged with 32.4 g of Nn-butylmaleimide and 0.054 g of dimethyl-2,2′-azobisisobutyrate as a polymerization initiator, and after substitution with nitrogen, a polymerization temperature of 60 ° C. and a polymerization time of 5 The radical polymerization reaction was performed under time conditions. After the reaction, chloroform was added to form a polymer solution, and the polymer was precipitated by mixing with excess methanol. The obtained polymer was filtered, washed sufficiently with methanol and dried at 80 ° C. to obtain 20 g of Nn-butylmaleimide polymer resin. The number average molecular weight of the obtained Nn-butylmaleimide polymer resin was 120,000.

Synthesis Example 2 (Production Example of Nn-Hexylmaleimide Polymer Resin)
In a glass sealed tube, 40 g of Nn-hexylmaleimide and 0.05 g of dimethyl-2,2′-azobisisobutyrate as a polymerization initiator are charged, and after nitrogen substitution, a polymerization temperature of 60 ° C. and a polymerization time of 5 hours. The radical polymerization reaction was performed under the following conditions. After the reaction, chloroform was added to form a polymer solution, and the polymer was precipitated by mixing with excess methanol. The obtained polymer was filtered, sufficiently washed with methanol, and dried at 80 ° C. to obtain 32 g of Nn-hexylmaleimide polymer resin. The number average molecular weight of the obtained Nn-hexylmaleimide polymer resin was 160000.

Synthesis Example 3 (Production Example of Nn-Octylmaleimide Polymer Resin)
In a glass sealed tube, 28 g of Nn-octylmaleimide and 0.032 g of dimethyl-2,2′-azobisisobutyrate as a polymerization initiator were charged, and after nitrogen substitution, a polymerization temperature of 60 ° C. and a polymerization time of 5 hours The radical polymerization reaction was performed under the following conditions. After the reaction, chloroform was added to form a polymer solution, and the polymer was precipitated by mixing with excess methanol. The obtained polymer was filtered, washed sufficiently with methanol, and dried at 80 ° C. to obtain 15 g of Nn-octylmaleimide polymer resin. The number average molecular weight of the obtained Nn-octylmaleimide polymer resin was 270000.

Synthesis Example 4 (Production Example 1 of Nn-octylmaleimide-maleic anhydride copolymer resin)
In a glass sealed tube, 26 g of Nn-octylmaleimide, 2.4 g of maleic anhydride, 0.036 g of dimethyl-2,2′-azobisisobutyrate as a polymerization initiator were charged, and after substitution with nitrogen, the polymerization temperature A radical polymerization reaction was carried out under conditions of 60 ° C. and a polymerization time of 5 hours. After the reaction, chloroform was added to form a polymer solution, and the polymer was precipitated by mixing with excess methanol. The obtained polymer was filtered, sufficiently washed with methanol, and dried at 80 ° C. to obtain 19 g of Nn-octylmaleimide-maleic anhydride copolymer resin. The obtained Nn-octylmaleimide-maleic anhydride copolymer resin contained 20% by weight of maleic anhydride residue, and the number average molecular weight was 120,000.

Synthesis Example 5 (Production Example 2 of Nn-octylmaleimide-maleic anhydride copolymer resin)
In a glass sealed tube, 26 g of Nn-octylmaleimide, 4.8 g of maleic anhydride and 0.04 g of dimethyl-2,2′-azobisisobutyrate as a polymerization initiator were charged, and after substitution with nitrogen, the polymerization temperature A radical polymerization reaction was carried out under conditions of 60 ° C. and a polymerization time of 5 hours. After the reaction, chloroform was added to form a polymer solution, and the polymer was precipitated by mixing with excess methanol. The obtained polymer was filtered, sufficiently washed with methanol, and dried at 80 ° C. to obtain 18 g of Nn-octylmaleimide-maleic anhydride copolymer resin. The obtained Nn-octylmaleimide-maleic anhydride copolymer resin contains 40% by weight of maleic anhydride residue units, and the number average molecular weight was 140000.

Example 1
The Nn-butylmaleimide polymer resin obtained in Synthesis Example 1 is dissolved in a solvent composed of 50% by weight of toluene and 50% by weight of ethyl methyl ketone to form a 12% solution. Further, the Nn-butylmaleimide polymer resin 100 is obtained. After adding 5 parts by weight of tricresyl phosphate as a plasticizer to parts by weight, it was coated on a 80 μm-thick triacetyl cellulose film (hereinafter referred to as TAC film) with a coater and dried at room temperature for 24 hours. A laminate of a coating film having a width of 50 mm and a thickness of 20 μm and a TAC film was obtained.

  The obtained laminate had a glass transition temperature of 178 ° C., a light transmittance of 91.7%, and a haze of 0.6%, and a three-dimensional refractive index of nx = 1.49374, ny = 1.49374, nz = 1. 49218, Rth was 155.8 nm, and R450 / R589 showing the wavelength dependency of the phase difference amount was 1.06. Moreover, the maximum point elongation of the obtained laminate was 15.3%, and the maximum point stress was 112 MPa.

  As a result, the obtained laminate had a function as an optical compensation film because of nx = ny> nz and small wavelength dependence, and was further excellent in elongation.

Example 2
A laminate of a coating film having a width of 50 mm and a thickness of 20 μm and a TAC film was obtained by the same method as in Example 1 except that the amount of tricresyl phosphate added was 10 parts by weight.

  The obtained laminate had a glass transition temperature of 177 ° C., a light transmittance of 91.8%, and a haze of 0.7%, and a three-dimensional refractive index of nx = 1.349359, ny = 1.49360, nz = 1. 49200, Rth was 159.5 nm, and R450 / R589 showing the wavelength dependency of the phase difference amount was 1.06. Moreover, the maximum point elongation of the obtained laminate was 14.8%, and the maximum point stress was 117 MPa.

  As a result, the obtained laminate had a function as an optical compensation film because of nx≈ny> nz and small wavelength dependence, and was further excellent in elongation.

Example 3
A laminate of a coating film having a width of 50 mm and a thickness of 20 μm and a TAC film was obtained in the same manner as in Example 1 except that the plasticizer was changed to tri (2-ethylhexyl) phosphate.

  The obtained laminate had a glass transition temperature of 179 ° C., a light transmittance of 92.3%, a haze of 0.6%, and a three-dimensional refractive index of nx = 1.43941, ny = 1.439341, nz = 1. 49189, Rth was 152.0 nm, and R450 / R589 showing the wavelength dependence of the phase difference amount was 1.06. Moreover, the maximum point elongation of the obtained laminate was 15.1%, and the maximum point stress was 117 MPa.

  As a result, the obtained laminate had a function as an optical compensation film because of nx = ny> nz and small wavelength dependence, and was further excellent in elongation.

Example 4
A laminate of a coating film having a width of 50 mm and a thickness of 20 μm and a TAC film was obtained in the same manner as in Example 1 except that the plasticizer was changed to trixylenyl phosphate.

  The obtained laminate had a glass transition temperature of 178 ° C., a light transmittance of 92.5%, and a haze of 0.7%, and a three-dimensional refractive index of nx = 1.439340, ny = 1.49340, nz = 1. 49182, Rth was 157.9 nm, and R450 / R589 showing the wavelength dependency of the phase difference amount was 1.06. Moreover, the maximum point elongation of the obtained laminate was 14.5%, and the maximum point stress was 121 MPa.

  As a result, the obtained laminate had a function as an optical compensation film because of nx = ny> nz and small wavelength dependence, and was further excellent in elongation.

Example 5
A laminate of a coating film having a width of 50 mm and a thickness of 20 μm and a TAC film was obtained in the same manner as in Example 1 except that the plasticizer was changed to bisphenol A bis (diphenyl phosphate).

  The obtained laminate had a glass transition temperature of 180 ° C., a light transmittance of 92.1%, a haze of 0.7%, and a three-dimensional refractive index of nx = 1.49383, ny = 1.49383, nz = 1. 49229, Rth was 153.5 nm, and R450 / R589 showing the wavelength dependency of the phase difference amount was 1.06. Moreover, the maximum point elongation of the obtained laminate was 15.2%, and the maximum point stress was 116 MPa.

  As a result, the obtained laminate had a function as an optical compensation film because of nx = ny> nz and small wavelength dependence, and was further excellent in elongation.

Example 6
A laminate of a coating film having a width of 50 mm and a thickness of 20 μm and a TAC film was obtained in the same manner as in Example 1 except that the plasticizer was changed to tributyl trimellitate.

  The obtained laminate had a glass transition temperature of 179 ° C., a light transmittance of 91.6%, and a haze of 0.6%, and a three-dimensional refractive index of nx = 1.49413, ny = 1.49413, nz = 1. 49257, Rth was 156.2 nm, and R450 / R589 showing the wavelength dependency of the phase difference amount was 1.05. Moreover, the maximum point elongation of the obtained laminate was 14.5%, and the maximum point stress was 113 MPa.

  As a result, the obtained laminate had a function as an optical compensation film because of nx = ny> nz and small wavelength dependence, and was further excellent in elongation.

Example 7
A laminate of a coating film having a width of 50 mm and a thickness of 20 μm and a TAC film was obtained in the same manner as in Example 1 except that the plasticizer was changed to tri (2-ethylhexyl) trimellitate.

  The obtained laminate had a glass transition temperature of 178 ° C., a light transmittance of 91.9% and a haze of 0.6%, and a three-dimensional refractive index of nx = 1.49306, ny = 1.49306, nz = 1. 49151, Rth was 154.8 nm, and R450 / R589 showing the wavelength dependence of the phase difference amount was 1.06. Moreover, the maximum point elongation of the obtained laminate was 15.3%, and the maximum point stress was 120 MPa.

  As a result, the obtained laminate had a function as an optical compensation film because of nx = ny> nz and small wavelength dependence, and was further excellent in elongation.

Example 8
A laminate of a coating film having a width of 50 mm and a thickness of 20 μm and a TAC film was obtained in the same manner as in Example 1 except that the plasticizer was changed to tri (2-ethylhexyl) pyromellitate.

  The obtained laminate had a glass transition temperature of 181 ° C., a light transmittance of 91.6%, and a haze of 0.6%, and a three-dimensional refractive index of nx = 1.49421, ny = 1.49421, nz = 1. 49265, Rth was 156.0 nm, and R450 / R589 showing the wavelength dependency of the phase difference amount was 1.06. Moreover, the maximum point elongation of the obtained laminate was 15.0%, and the maximum point stress was 110 MPa.

  As a result, the obtained laminate had a function as an optical compensation film because of nx = ny> nz and small wavelength dependence, and was further excellent in elongation.

Example 9
The Nn-hexylmaleimide polymer resin obtained in Synthesis Example 2 is dissolved in a solvent composed of 50% by weight of toluene and 50% by weight of ethyl methyl ketone to form a 15% solution. Further, the Nn-hexylmaleimide polymer resin 100 is obtained. After adding 5 parts by weight of tricresyl phosphate as a plasticizer to parts by weight, it was coated on a TAC film having a thickness of 80 μm by a coater, dried at room temperature for 24 hours, and a coating film having a width of 50 mm and a thickness of 20 μm and TAC A laminate with a film was obtained.

  The obtained laminate had a glass transition temperature of 178 ° C., a light transmittance of 91.8%, a haze of 0.7%, and a three-dimensional refractive index of nx = 1.49552, ny = 1.49552, nz = 1. 49441, Rth was 110.8 nm, and R450 / R589 showing the wavelength dependency of the phase difference amount was 1.06. Moreover, the maximum point elongation of the obtained laminate was 16.3%, and the maximum point stress was 110 MPa.

  As a result, the obtained laminate had a function as an optical compensation film because of nx = ny> nz and small wavelength dependence, and was further excellent in elongation.

Example 10
The Nn-octylmaleimide polymer resin obtained in Synthesis Example 3 is dissolved in a solvent composed of 50% by weight of toluene and 50% by weight of ethyl methyl ketone to form a 16% solution. Further, the Nn-octylmaleimide polymer resin 100 is obtained. After adding 5 parts by weight of tricresyl phosphate as a plasticizer to parts by weight, it was coated on a TAC film having a thickness of 80 μm by a coater, dried at room temperature for 24 hours, and a coating film having a width of 50 mm and a thickness of 20 μm and TAC A laminate with a film was obtained.

  The obtained laminate had a glass transition temperature of 177 ° C., a light transmittance of 92.8%, and a haze of 0.9%, and a three-dimensional refractive index of nx = 1.49330, ny = 1.49330, nz = 1. 49249, Rth was 81.1 nm, and R450 / R589 showing the wavelength dependence of the phase difference amount was 1.05. Moreover, the maximum point elongation of the obtained laminate was 14.9%, and the maximum point stress was 118 MPa.

  As a result, the obtained laminate had a function as an optical compensation film because of nx = ny> nz and small wavelength dependence, and was further excellent in elongation.

Example 11
The Nn-octylmaleimide-maleic anhydride copolymer resin obtained in Synthesis Example 4 was dissolved in a solvent composed of 50% by weight of toluene and 50% by weight of ethyl methyl ketone to form a 16% solution, and further Nn-octyl. After adding 5 parts by weight of tricresyl phosphate as a plasticizer to 100 parts by weight of maleimide-maleic anhydride copolymer resin, it is coated on a TAC film having a thickness of 80 μm by a coater, and dried at room temperature for 24 hours. A laminate of a coating film having a thickness of 50 mm and a thickness of 20 μm and a TAC film was obtained.

  The obtained laminate had a glass transition temperature of 178 ° C., a light transmittance of 92.2%, and a haze of 0.8%, and a three-dimensional refractive index of nx = 1.49245, ny = 1.49245, nz = 1. 49156, Rth was 89.5 nm, and R450 / R589, which indicates the wavelength dependency of the phase difference amount, was 1.05. Moreover, the maximum point elongation of the obtained laminate was 14.7%, and the maximum point stress was 111 MPa.

  As a result, the obtained laminate had a function as an optical compensation film because of nx = ny> nz and small wavelength dependence, and was further excellent in elongation.

Example 12
The Nn-octylmaleimide-maleic anhydride copolymer resin obtained in Synthesis Example 5 was dissolved in a solvent composed of 50% by weight of toluene and 50% by weight of ethyl methyl ketone to form a 16% solution, and further Nn-octyl. After adding 5 parts by weight of tricresyl phosphate as a plasticizer to 100 parts by weight of maleimide-maleic anhydride copolymer resin, it is coated on a TAC film having a thickness of 80 μm by a coater, and dried at room temperature for 24 hours. A laminate of a coating film having a thickness of 50 mm and a thickness of 20 μm and a TAC film was obtained.

  The obtained laminate had a glass transition temperature of 179 ° C., a light transmittance of 92.0%, a haze of 0.9%, and a three-dimensional refractive index of nx = 1.49249, ny = 1.49249, nz = 1. 49159, Rth was 90.4 nm, and R450 / R589 showing the wavelength dependence of the phase difference amount was 1.05. Moreover, the maximum point elongation of the obtained laminate was 15.4%, and the maximum point stress was 114 MPa.

  As a result, the obtained laminate had a function as an optical compensation film because of nx = ny> nz and small wavelength dependence, and was further excellent in elongation.

Comparative Example 1
Into a 1 liter autoclave, 400 ml of toluene as a polymerization solvent, 0.001 mol of perbutyl neodecanoate as a polymerization initiator, 0.42 mol of N- (2,6-diethylphenyl) maleimide, 4.05 mol of isobutene were charged. A polymerization reaction was performed at a polymerization temperature of 60 ° C. and a polymerization time of 5 hours to obtain an N- (2,6-diethylphenyl) maleimide-isobutene alternating copolymer. The obtained N- (2,6-diethylphenyl) maleimide-isobutene alternating copolymer had a weight average molecular weight (Mw) = 170,000 and Mw / Mn = 2.6.

  A solution comprising 20% by weight of the obtained N- (2,6-diethylphenyl) maleimide-isobutene alternating copolymer and 80% by weight of methylene chloride was prepared, and N- (2,6-diethylphenyl) maleimide-isobutene was further prepared. N- (2) formed after a solution in which 5 parts by weight of tricresyl phosphate as a plasticizer is added to 100 parts by weight of an alternating copolymer is coated on a PET film and methylene chloride is volatilized and solidified from the solution. , 6-Diethylphenyl) maleimide-isobutene alternating copolymer film was peeled off. The peeled film was further dried at 100 ° C. for 4 hours, 120 ° C. to 160 ° C. at 10 ° C. intervals for 1 hour, and then dried at 180 ° C. for 4 hours in a vacuum dryer to a thickness of about 100 μm. A film having was obtained. (The three-dimensional refractive index of the obtained film is nx = 1.5400, ny = 1.5400, nz = 1.5400, and nx = ny = nz). The obtained film had a glass transition temperature of 135 ° C., a maximum point elongation of 8.8%, and a maximum point stress of 132 MPa.

  A small piece of 5 cm × 5 cm was cut out from the film, and the temperature was 220 ° C. and the stretching speed was 15 mm / min. Using a biaxial stretching device (manufactured by Shibayama Kagaku Kikai). A stretched film was obtained by subjecting the film to a free width uniaxial stretching under the conditions of + 50% stretching. The obtained stretched film had a three-dimensional refractive index of nx = 1.53916, ny = 1.54050, nz = 1.54050, Rth was −67.0 nm, and nx <ny = nz.

  Therefore, an optical compensation film having an optical compensation function cannot be obtained only by coating.

Claims (10)

A coating film composed of a maleimide resin and a plasticizer, wherein any two axes orthogonal in the plane of the coating film are x-axis and y-axis, the out-of-plane direction is z-axis, and the refractive index in the x-axis direction A three-dimensional refractive index relationship where nx≈ny> nz, where nx is the refractive index in the y-axis direction, ny is the refractive index in the y-axis direction, and nz is the refractive index in the z-axis direction. 2. The optical compensation film according to claim 1, comprising a maleimide resin composed of an N-substituted maleimide residue unit represented by the following general formula (1).

(Here, R ₁ represents a linear alkyl group having 1 to 18 carbon atoms, a branched alkyl group, a cyclic alkyl group, a halogen group, an ether group, an ester group, or an amide group.) The optical compensation according to claim 1 or 2, wherein an out-of-plane retardation (Rth) represented by the following formula (2) when measured with light having a measurement wavelength of 589 nm is in a range of 30 to 2000 nm. film.
Rth = ((nx + ny) / 2−nz) × d (2)
(Here, d represents the film thickness (nm) of the optical compensation film.) The wavelength dependence of the phase difference amount indicated by the ratio of the phase difference amount (R450) measured with light having a measurement wavelength of 450 nm with the coating film inclined by 40 degrees and the phase difference amount (R589) measured with light having a measurement wavelength of 589 nm ( The optical compensation film according to any one of claims 1 to 3, wherein R450 / R589) is 1.1 or less. The optical compensation film according to claim 1, wherein the coating film is an unstretched film. 6. The optical compensation film according to claim 1, which is an optical compensation film for a liquid crystal display element. It is a laminated body of the optical compensation film in any one of Claims 1-6, and a cellulose resin film, The optical compensation film characterized by the above-mentioned. The optical compensation film according to claim 7, which is an optical compensation film for a liquid crystal display element. A method for producing an optical compensation film, comprising: applying a solution comprising a maleimide resin and a plasticizer on a substrate and drying the solution. The method for producing an optical compensation film according to claim 9, wherein the maleimide resin solution is a solution of a maleimide resin comprising a maleimide residue unit represented by the general formula (1).