JP2006283010A - Optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film with low birefringence caused by drawing and small photoelastic coefficient. <P>SOLUTION: The optical film composed of a block copolymer comprising a polymer block A comprising at least an aromatic vinyl hydrocarbon as an essential component and a block B comprising a polymer comprising at least a conjugated diene as an essential component. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical film having excellent optical properties.

  Recently, for example, with the expansion of the display market, there has been an increasing demand for clearer images, and there is a demand for optical materials with higher optical properties rather than simple transparent materials. Generally, a polymer has birefringence due to the orientation of the molecular chain because the refractive index differs between the molecular main chain direction and the perpendicular direction. Depending on the application, it is required to strictly control this birefringence. In the case of a protective film used for a polarizing plate of a liquid crystal, a polymer material having a smaller birefringence even if the total light transmittance is the same. On the other hand, a quarter-wave plate having a function of converting light polarized by a polarizing plate into circularly polarized light gives a function by consciously generating birefringence in a polymer material molded body. ing.

  When a polymer material is used for these applications, a molded body is produced by extrusion molding or cast molding. For example, when an extruded product is applied to a polarizing plate protective film, there is a problem that the influence of orientation during melt molding tends to remain and birefringence occurs. Furthermore, when applied to a retardation film such as a quarter-wave plate, after obtaining a non-oriented film by cast molding or the like, it causes arbitrary birefringence by stretching, but birefringence is large by slightly stretching. The resulting material is difficult to control the phase difference (see, for example, Patent Document 1). A polycarbonate resin is known as a typical material for a retardation film. However, since this resin has a large change in birefringence due to stretching, there is a demand for improvement regarding controllability of retardation. For these reasons, there has been a demand for a material that has a gentle birefringence change even when stretched.

Also, in recent years, as liquid crystal displays have become larger, and polymer optical material moldings required for them have become larger, materials that have small changes in birefringence due to external forces in order to reduce the distribution of birefringence caused by bias of external forces. Is required. For this purpose, a polymer optical material having a low photoelastic coefficient is required as a new required characteristic, and methyl methacrylate homopolymer (PMMA) and amorphous polyolefin (APO) are known as materials having a low photoelastic coefficient. (For example, refer nonpatent literature 1). However, since these materials still have a large change in birefringence due to an external force, a material having a smaller photoelastic coefficient has been desired.
JP-A-11-183724 Chemical Review, No. 39, 1998 (published by Academic Publishing Center)

  An object of the present invention is to provide an optical film having a small change in birefringence due to stretching and a small photoelastic coefficient.

The present inventors have surprisingly found that an optical film made of a block copolymer has a small birefringence change due to stretching and a small photoelastic coefficient, and has completed the present invention.
That is, the present invention
[1] An optical film comprising a block copolymer comprising a polymer block A mainly composed of at least one vinyl aromatic hydrocarbon and a polymer block B mainly composed of at least one conjugated diene,
[2] An optical film comprising a block copolymer having at least two polymer blocks A and at least one of the polymer blocks A containing a conjugated diene,
[3] The optical film according to [1], comprising a block copolymer having a vinyl aromatic hydrocarbon content of 45 to 99% by mass,
[4] The optical film according to [2], comprising a block copolymer having a vinyl aromatic hydrocarbon content of 55 to 99% by mass,
[5] The optical film according to any one of [1] to [4], comprising a block copolymer containing 1,3-butadiene as a conjugated diene,
[6] The olefinically unsaturated double bond in the polymer block B is composed of a block copolymer hydrogenated by 5 to 100% [1], [3], [4] and [ 5], an optical film according to any one of
[7] The unsaturated double bond of the aromatic ring of the vinyl aromatic compound in the polymer block A is composed of a block copolymer hydrogenated by 5 to 100% [1] to [6] The optical film according to any one of
[8] The olefinically unsaturated double bond of the entire block copolymer is composed of a block copolymer hydrogenated by 5 to 100%, according to any one of [1] to [5] Optical film,
[9] The olefinically unsaturated double bond of the entire block copolymer is composed of a block copolymer hydrogenated by 85 to 100%, according to any one of [1] to [5] Optical film,
[10] The block copolymer in which the unsaturated double bond of the aromatic ring of the vinyl aromatic compound in the entire block copolymer is 5 to 100% hydrogenated is provided [1] to [5] , [8] and [9].
[11] The block copolymer in which the unsaturated double bond of the aromatic ring of the vinyl aromatic compound of the entire block copolymer is a hydrogenated 85-100% block copolymer. , [8] and the optical film according to any one of [9],
[12] The unsaturated double bond of the aromatic ring of the vinyl aromatic compound in the entire block copolymer is hydrogenated by 90 to 100%, and the olefinically unsaturated double bond of the entire block copolymer is 90 to 100%. % Of the optical film according to any one of [1] to [5], wherein the optical film is made of a hydrogenated block copolymer;
[13] The optical film according to any one of [1] to [12], which is stretched,
[14] A resin in which the value of the slope K obtained from the least square approximation satisfies the following formula in the relationship between the birefringence (Δn (S)) and the draw ratio (S) when the block copolymer is stretched: The optical film according to any one of [1] to [13],
K = Δn (S) / S
−2.0 × 10 ⁻⁵ <K <2.0 × 10 ⁻⁵
[15] The optical film according to any one of [1] to [14], which is a film formed by extrusion molding
[16] The optical film according to any one of [1] to [14], which is a film formed by cast molding,
[17] The optical film according to any one of [1] to [16], wherein the photoelastic coefficient is 30 × 10 ⁻¹² Pa ⁻¹ or less,
[18] A retardation film using the optical film according to any one of [1] to [17], wherein the retardation is 10 nm to 300 nm, and the draw ratio is 10% to 450%.
[19] A polarizing plate protective film comprising the optical film according to any one of [1] to [17], wherein the retardation is 0 nm to 10 nm.
It is.

  According to the present invention, it is possible to provide a polymer optical film having a small change in birefringence and a small photoelastic coefficient when stretched due to a molding factor necessary for a display or the like or arbitrarily stretched.

Hereinafter, the present invention will be specifically described.
The block copolymer used in the present invention is a block copolymer having a polymer block A mainly composed of at least one vinyl aromatic hydrocarbon and a polymer block B mainly composed of at least one conjugated diene. is there.
Furthermore, the block copolymer used in the present invention is a block copolymer having at least two polymer blocks A and at least one of the polymer blocks A containing a conjugated diene.
Here, the polymer block A mainly composed of vinyl aromatic hydrocarbon is a copolymer block of vinyl aromatic hydrocarbon and conjugated diene containing vinyl aromatic hydrocarbon content of 50% by mass or more and / or vinyl aromatic. A polymer block B mainly showing a conjugated diene is a conjugated diene and vinyl aromatic hydrocarbon copolymer block and / or conjugated containing a conjugated diene in an amount exceeding 50% by mass. This refers to a diene homopolymer block.

When a random copolymer portion of vinyl aromatic hydrocarbon and conjugated diene is present in polymer block A mainly composed of vinyl aromatic hydrocarbon or polymer block B mainly composed of conjugated diene, The vinyl aromatic hydrocarbon may be distributed uniformly in the polymer block or may be distributed in a tapered shape. Further, the copolymer portion may coexist with a plurality of portions where vinyl aromatic hydrocarbons are uniformly distributed and / or portions where they are distributed in a tapered shape.
When the block copolymer of the present invention has a plurality of polymer blocks A (or B), they may be different in molecular weight, composition, type and the like.

The block copolymer used in the present invention can basically be produced by a conventionally known method. For example, Japanese Patent Publication No. 36-19286, Japanese Patent Publication No. 43-17879, Japanese Patent Publication No. 48-2423, The methods described in Japanese Patent Publication No. 49-36957, Japanese Patent Publication No. 57-49567, Japanese Patent Publication No. 58-11446, and the like can be mentioned. The production conditions of each constituent polymer are set so as to satisfy the requirements described later. There must be. All of the above known methods are methods in which a conjugated diene and a vinyl aromatic hydrocarbon are block copolymerized using an anionic initiator such as an organic lithium compound in a hydrocarbon solvent. The block copolymer used in the present invention has, for example, A- (BA) _n , A- (BA) _n -B, B- (AB) _{n + 1}
[In the above formula, A is a polymer block mainly composed of vinyl aromatic hydrocarbons, and B is a polymer block mainly composed of conjugated dienes. The boundary between the A block and the B block does not necessarily have to be clearly distinguished. n is an integer of 1 or more, generally 1 to 5. ], Or ((AB) _k ] _{m + 2} -X, [(AB) _k -A] _{m + 2} -X, [(BA) _k ] _{M + 2} −X,
[(B−A) _k −B] _{m + 2} −X
[In the above formula, A and B are the same as described above, and k and m are integers of 1 or more, generally 1 to 5. X represents a residue of a coupling agent such as silicon tetrachloride or tin tetrachloride or a residue of an initiator such as a polyfunctional organolithium compound. Or a mixture of arbitrary polymer structures of these block copolymers can be used.

  Examples of the vinyl aromatic hydrocarbon used in the present invention include styrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinylanthracene, 1,1-diphenylethylene and the like can be mentioned, and styrene is particularly commonly mentioned. These may be used alone or in combination of two or more. The conjugated diene is a diolefin having a pair of conjugated double bonds, such as 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene. 1,3-pentadiene, 1,3-hexadiene and the like. Representative conjugated dienes include 1,3-butadiene, isoprene and the like. These may be used alone or in combination of two or more.

When 1,3-butadiene and isoprene are used in combination, 1,3-butadiene is preferably 10% by mass or more, more preferably 25% by mass or more, and particularly preferably 40% by mass or more. When 1,3-butadiene is 10% by mass or more, thermal decomposition does not occur during molding and the molecular weight does not decrease, so that it can be preferably used as an optical film. Further, in the case of a hydrogenated block copolymer, when 1,3-butadiene is 10% by mass or more, the film is excellent in mechanical strength, and thus is preferably used as an optical film.
Examples of the hydrocarbon solvent include aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane, and octane, alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane, or benzene, Aromatic hydrocarbons such as toluene, ethylbenzene and xylene can be used. These may be used alone or in combination of two or more.

Examples of the organic lithium compound include an organic monolithium compound, an organic dilithium compound, and an organic polylithium compound in which one or more lithium atoms are bonded in the molecule. Specific examples of these include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, hexamethylene dilithium, butadienyl dilithium, isoprenyl dilithium, and the like. Can be mentioned. These may be used alone or in combination of two or more.
In the present invention, polar compounds or the like are used for the purpose of adjusting the polymerization rate, changing the microstructure of the polymerized conjugated diene moiety (ratio of cis, trans, vinyl), adjusting the reaction ratio of conjugated diene and vinyl aromatic hydrocarbon, and the like. Randomizing agents can be used. Examples of polar compounds and randomizing agents include ethers such as tetrahydrofuran, diethylene glycol dimethyl ether and diethylene glycol dibutyl ether, amines such as triethylamine and tetramethylethylenediamine, thioethers, phosphines, phosphoramides, alkylbenzene sulfonates, potassium and sodium. An alkoxide etc. are mentioned.

  The polymerization temperature when producing the polymer in the method of the present invention is generally in the range of -10 ° C to 150 ° C, preferably 40 ° C to 120 ° C. The time required for polymerization varies depending on the conditions, but is usually within 48 hours, and particularly preferably in the range of 1 to 10 hours. The polymerization atmosphere is preferably replaced with an inert gas such as nitrogen gas. The polymerization pressure is not particularly limited as long as the polymerization pressure is in a range sufficient to maintain the monomer and the solvent in the liquid layer within the above polymerization temperature range. Furthermore, care must be taken not to mix impurities, such as water, oxygen, carbon dioxide, etc., that inactivate the catalyst and living polymer into the polymerization system.

The block copolymer used in the present invention is a block copolymer comprising a polymer block A mainly composed of at least one vinyl aromatic hydrocarbon and a polymer block B mainly composed of at least one conjugated diene. In this case, the vinyl aromatic hydrocarbon content of the block copolymer is preferably 45 to 99% by mass, more preferably 65 to 95% by mass, and particularly preferably 70 to 90% by mass. A vinyl aromatic hydrocarbon content of the block copolymer of 45% by mass or more is preferable because the resin composition molded article is excellent in rigidity and transparency.
Further, when the block copolymer used in the present invention has at least two polymer blocks A and at least one of the polymer blocks A is a block copolymer containing a conjugated diene, The range of the vinyl aromatic hydrocarbon content of the coalescence is preferably 55 to 99% by mass, more preferably 65 to 95% by mass, and particularly preferably 70 to 90% by mass. A vinyl aromatic hydrocarbon content of the block copolymer of 55% by mass or more is preferable because the resin composition molded article is excellent in rigidity and transparency.

In the present invention, the preferred range of the block ratio of the vinyl aromatic hydrocarbon polymer block incorporated in the block copolymer is 50 to 100% by mass. A block ratio of 50% by mass or more is preferable because the resin composition molded article is excellent in rigidity. The block ratio of the vinyl aromatic hydrocarbon block is the weight and weight ratio of the vinyl aromatic hydrocarbon and the conjugated diene in the process of copolymerizing at least a part of the vinyl aromatic hydrocarbon and the conjugated diene during the production of the block copolymer. It can be controlled by changing the polymerization reactivity ratio and the like. Specific methods include:
(A) A mixture of a vinyl aromatic hydrocarbon and a conjugated diene is continuously supplied to the polymerization system for polymerization, and / or (b) a vinyl aromatic hydrocarbon using a polar compound or a randomizing agent. And a method of copolymerizing a conjugated diene and the like.

  Examples of polar compounds and randomizing agents include ethers such as tetrahydrofuran, diethylene glycol dimethyl ether and diethylene glycol dibutyl ether, amines such as triethylamine and tetramethylethylenediamine, thioethers, phosphines, phosphoramides, alkylbenzene sulfonates, potassium and sodium. An alkoxide etc. are mentioned. In the present invention, the block ratio of the vinyl aromatic hydrocarbon polymer block incorporated in the block copolymer means that the block copolymer is oxidized with di-tertiary butyl hydroperoxide using osmium tetroxide as a catalyst. Decomposition method [I. M.M. KOLTHOFF, et al. , J .; Polym. Sci. 1,429 (1946)], and the vinyl aromatic hydrocarbon polymer block component (excluding vinyl aromatic hydrocarbon polymer components having an average degree of polymerization of about 30 or less) was determined. The value obtained from the following equation.

Vinyl aromatic of block copolymer
Mass% of hydrocarbon polymer block
Block ratio (mass%) = ――――――――――――――――― × 100
All vinyl block copolymer
% By mass of aromatic hydrocarbon

The block ratio of the hydrogenated block copolymer is analyzed using the polymer before hydrogenation.

The block copolymer used in the present invention can be used as a hydrogenated product by hydrogenation in the presence of a hydrogenation catalyst in an inert solvent if desired. As specific methods, the methods described in JP-B-42-8704 and JP-B-43-6636 are described, and particularly preferably described in JP-B-63-4841 and JP-B-63-5401. Is the method.
In the present invention, a block copolymer in which 5 to 100% of the olefinically unsaturated double bond of the entire block copolymer is hydrogenated can be preferably used as an optical film. The olefinically unsaturated double bond in the block copolymer causes yellowing or a decrease in light transmittance due to heat or light. Further, the photoelastic coefficient can be reduced by hydrogenation of the olefinically unsaturated double bond. Therefore, it is preferable to hydrogenate the olefinically unsaturated double bond for use as an optical film. A more preferable range of hydrogenation of the olefinically unsaturated double bond is 85 to 100%, and a particularly preferable range is 90 to 99.9%.

In the present invention, a block copolymer in which 5 to 100% of the olefinically unsaturated double bond in the polymer block B is hydrogenated can be preferably used as an optical film. The olefinically unsaturated double bond in the block copolymer causes yellowing or a decrease in light transmittance due to heat or light. Further, the photoelastic coefficient can be reduced by hydrogenation of the olefinically unsaturated double bond. Therefore, it is preferable to hydrogenate the olefinically unsaturated double bond for use as an optical film. A more preferable range of hydrogenation of the olefinically unsaturated double bond is 85 to 100%, and a particularly preferable range is 90 to 99.9%.
Moreover, it is preferable that the unsaturated double bond of the aromatic ring of the whole vinyl aromatic compound in a block copolymer is hydrogenated 5 to 100% in the whole vinyl aromatic compound. Hydrogenation of the unsaturated double bond of the aromatic ring has an effect of suppressing the wavelength dependency of retardation. In addition, the photoelastic coefficient is reduced. A more preferable range of hydrogenation is 85 to 100%, and a particularly preferable range is 90 to 99.9%.

Moreover, it is preferable that the unsaturated double bond of the aromatic ring of the vinyl aromatic compound in the polymer block A is hydrogenated 5 to 100% in the whole vinyl aromatic compound. Hydrogenation of the unsaturated double bond of the aromatic ring has an effect of suppressing the wavelength dependency of retardation. In addition, the photoelastic coefficient is reduced. A more preferable range of hydrogenation is 85 to 100%, and a particularly preferable range is 90 to 99.9%.
In the present invention, when both the unsaturated double bond of the aromatic ring of the vinyl aromatic compound and the olefinically unsaturated double bond are hydrogenated, the aromatic ring of the vinyl aromatic compound in the entire block copolymer is not hydrogenated. The saturated double bond is preferably hydrogenated by 90 to 100%, and the olefinically unsaturated double bond of the entire block copolymer is preferably hydrogenated by 90 to 100%.

The degree of hydrogenation of the block copolymer in the present invention is measured as a hydrogenation rate. A method for measuring the hydrogenation rate will be described in Examples.
The method for the hydrogenation reaction of the block copolymer is not particularly limited, but a method in which only the olefinically unsaturated double bond is hydrogenated, both the olefinically unsaturated double bond and the aromatic unsaturated double bond are hydrogenated. Can be divided into methods.
The hydrogenation catalyst for hydrogenating only olefinically unsaturated double bonds is not particularly limited, and conventionally known (1) metals such as Ni, Pt, Pd, and Ru are carbon, silica, alumina, and diatomaceous earth. A supported heterogeneous hydrogenation catalyst supported on soil or the like, (2) a so-called organic acid salt such as Ni, Co, Fe, Cr or a transition metal salt such as acetylacetone salt and a reducing agent such as organoaluminum Ziegler type hydrogenation catalysts and (3) homogeneous hydrogenation catalysts such as so-called organometallic complexes such as organometallic compounds such as Ti, Ru, Rh and Zr are used. Specific examples of the hydrogenation catalyst include Japanese Patent Publication No. 42-8704, Japanese Patent Publication No. 43-6636, Japanese Patent Publication No. 63-4841, Japanese Patent Publication No. 1-39770, Japanese Patent Publication No. 1-53851, The hydrogenation catalyst described in Japanese Patent Publication No. 2-9041 can be used. A preferred hydrogenation catalyst is a mixture with a titanocene compound and / or a reducing organometallic compound.

As the titanocene compound, a compound described in JP-A-8-109219 can be used. Specific examples thereof include (substitution) such as biscyclopentadienyl titanium dichloride and monopentamethylcyclopentadienyl titanium trichloride. Examples thereof include compounds having at least one ligand having a cyclopentadienyl skeleton, an indenyl skeleton, or a fluorenyl skeleton. Examples of the reducing organometallic compound include organic alkali metal compounds such as organolithium, organomagnesium compounds, organoaluminum compounds, organoboron compounds, and organozinc compounds.
The hydrogenation reaction in which only the olefinically unsaturated double bond is hydrogenated is generally carried out in a temperature range of 0 to 200 ° C, more preferably 30 to 150 ° C. The pressure of hydrogen used in the hydrogenation reaction for hydrogenating only olefinically unsaturated double bonds is 0.1 to 15 MPa, preferably 0.2 to 10 MPa, more preferably 0.3 to 7 MPa. . The hydrogenation reaction time for hydrogenating only the olefinically unsaturated double bond is usually 3 minutes to 10 hours, preferably 10 minutes to 5 hours. The hydrogenation reaction in which only the olefinically unsaturated double bonds are hydrogenated can be used either in a batch process, a continuous process, or a combination thereof.

  A hydrogenation reaction in which both an olefinically unsaturated double bond and an unsaturated double bond of an aromatic ring are hydrogenated is a dilution system in a solvent in which the block copolymer is dissolved sufficiently and is not hydrogenated. Will be implemented. The working concentration is usually 5% to 40% by weight. If it is 5 mass% or more, a sufficient hydrogenation reaction rate can be obtained. Moreover, if it is 40 mass% or less, a viscosity is low enough and it can fully remove the heat_generation | fever which generate | occur | produces at the time of hydrogenation. The hydrogenation temperature can be appropriately selected from 20 ° C to 180 ° C. Within this range, a sufficient hydrogenation rate can be obtained, and deterioration of the hydrogenation catalyst is not a problem, and selective hydrogenation of aromatic rings and nonconjugated unsaturated double bonds in the polymer chain is carried out. It is possible. The hydrogenation pressure varies depending on the type of hydrogenation catalyst, but it can be appropriately selected from 0.5 MPa to 10 MPa.

  The hydrogenation catalyst for hydrogenating both the olefinically unsaturated double bond and the unsaturated double bond of the aromatic ring used in the present invention can be of any type and amount as long as the required hydrogenated polymer structure is obtained. Is not limited. Hydrogenation catalysts include Group 4, Group 6, Group 7, Group 8, Group 9, Group 10 metals, specifically titanium, zirconium, hafnium, molybdenum, iron, cobalt, nickel, rhenium, ruthenium, rhodium, palladium. It is possible to use a homogeneous hydrogenation catalyst or a heterogeneous hydrogenation catalyst containing at least one metal selected from platinum.

  The homogeneous hydrogenation catalyst that hydrogenates both the olefinically unsaturated double bond and the unsaturated double bond of the aromatic ring is an organometallic compound or metal complex of the above metal that is soluble in the reaction system. As a ligand of the metal complex, an appropriate element such as hydrogen, halogen, nitrogen compound, carboxylic acid, or organic compound can be arbitrarily selected. Specific examples of the ligand include hydrogen, fluorine, chlorine, bromine, nitric oxide, carbon monoxide, and compounds such as hydroxyl, ether, amine, thiol, phosphine, carbonyl, olefin, and various dienes. I can do it. Moreover, it is possible to use together the organometallic compound of 1st group, 2nd group, 13th group, such as alkyl lithium, alkyl magnesium, and alkyl aluminum, as a reducing agent as needed. Specific examples of the homogeneous hydrogenation catalyst include nickel naphthenate, nickel octoate, nickel acetyl acetate, nickel chloride, nickel carbonyl, nickelocene, cobalt naphthenate, cobalt octoate, cobalt acetyl acetate, cobalt chloride, cobalt carbonyl, Examples of titanium complexes include dicyclopentadienyl titanium dichloride, examples of ruthenium complexes include chlorohydridocarbonyltris (triphenylphosphine) ruthenium, dichlorotris (triphenylphosphine) ruthenium, and dihydridocarbonyltris (triphenylphosphine) ruthenium. .

In the present invention, the amount of the homogeneous hydrogenation catalyst for hydrogenating both the olefinically unsaturated double bond and the unsaturated double bond of the aromatic ring is appropriately selected depending on the hydrogenation conditions. The concentration is preferably in the range of 1 ppm to 2000 ppm, more preferably in the range of 10 ppm to 500 ppm. When the amount of the catalyst used is 1 mass ppm to 2000 mass ppm, a sufficient reaction rate can be obtained, the coloring of the product does not become a problem, and it is necessary to apply a great deal of effort to the separation and recovery of the catalyst metal. It is preferable because it is absent.
Heterogeneous hydrogenation catalysts that hydrogenate both olefinically unsaturated double bonds and unsaturated double bonds of aromatic rings are the above metals or oxides of the above metals, alumina, silica, activated carbon, barium sulfate, oxidation It is supported on magnesium, titania or the like, or the metal powder or metal oxide powder itself, and is insoluble in the reaction system. As a method for the reaction, hydrogenation of the polymer solution and the heterogeneous hydrogenation catalyst powder as a dispersion can be carried out. Alternatively, the heterogeneous hydrogenation catalyst is packed in a reaction tower and the polymer solution is allowed to flow continuously. It is also possible to make it.

  Examples of the metal used by supporting the olefinic unsaturated double bond and the unsaturated double bond of the aromatic ring on a support in the catalyst include those so-called noble metals. Specific examples include rhenium, ruthenium, rhodium, palladium, platinum, and the like, but palladium is preferable because side reactions such as molecular cleavage are small. As the type of support, carbon, silica, and alumina are preferable from the viewpoint of hydrogenation activity, but alumina is particularly preferable when comprehensively considering catalyst recovery and recyclability after reaction, product color, and the like. Examples of heterogeneous catalysts other than noble metals include Raney nickel catalysts.

As a specific example of a catalyst in which a noble metal used for a heterogeneous hydrogenation catalyst for hydrogenating both an olefinically unsaturated double bond and an unsaturated double bond of an aromatic ring is supported on a support, 2% by mass platinum alumina Powder (carrier: alumina powder, specific surface area 80-100 m ² / g) (manufactured by N.E. Chemcat Co., Ltd.), 5 mass% palladium alumina powder (carrier: alumina powder, specific surface area 80-100 m ² / g) ( 5% by mass palladium carbon powder (carrier: carbon powder, specific surface area 900-1300 m ² / g, water-containing product) (manufactured by N.E. Chemcat Co., Ltd.), 5% by mass palladium silica alumina powder (carrier: silica-alumina powder, a specific surface area of 400-600m ² / g) (manufactured by NE Chemcat Corporation), 5 wt% Ruteni Muarumina powder (carrier: alumina powder, a specific surface area 80~100m ² / g) (manufactured by NE Chemcat Corporation), 5 wt% rhenium alumina powder (carrier: alumina powder, a specific surface area 80~100m ² / g) (Made by N.E. Chemcat Co., Ltd.). Specific examples of heterogeneous hydrogenation catalysts other than noble metals include so-called Raney nickel catalysts such as sponge nickel catalysts (trade names: R-100, R-200 manufactured by Nikko Rica Co., Ltd.). These are the steps of dissolving and removing the aluminum component in the nickel-aluminum alloy with an aqueous sodium hydroxide solution, that is, a process generally called development, and then from the water dispersion state to the methanol dispersion state, then the tetrahydrofuran dispersion state, and finally the hydrogenated solvent dispersion. After replacing the solvent to the state, it is added to the reaction system.

The amount of the heterogeneous hydrogenation catalyst used to hydrogenate both the olefinically unsaturated double bond and the unsaturated double bond of the aromatic ring is 0.1% by mass as the metal concentration relative to the polymer present in the reaction system. It is the range of -1,000 mass%, Preferably it is the range of 0.5 mass%-300 mass%, More preferably, it is the range of 1.0 mass%-150 mass%.
The reaction time for hydrogenating both the olefinically unsaturated double bond and the unsaturated double bond of the aromatic ring depends on the reaction conditions such as the concentration of the reaction system, the amount of catalyst, the reaction temperature, and the target hydrogenation rate. It can be completed within 1 hour or more and within 24 hours. Heterogeneous hydrogenation catalysts have a better product color than homogeneous catalysts, and can be easily reused after separation and recovery if the reaction system does not contain poisonous substances such as halogen, sulfur, and phosphorus. Therefore, it is industrially preferable to a homogeneous hydrogenation catalyst.

If it is necessary to obtain a high purity hydrogenated block copolymer with extremely reduced hydrogenation catalyst metal that hydrogenates both olefinically unsaturated double bonds and unsaturated double bonds of aromatic rings, A method of extracting and removing metal ions in a hydrogenated block copolymer solution by water contact with high-purity ion exchange water after solubilizing with a suitable chelating agent, and a method for removing ionic impurities using an ion exchange resin column The metal ion and low molecular amine removal method using the carbon dioxide supercritical method can be carried out as necessary.
In the optical film of the present invention, there are uses where the film needs birefringence and uses not necessary. Applications that do not require birefringence are, for example, polarizing plate protective films, and applications that require birefringence are, for example, retardation films.

The optical film of the present invention is preferably stretched in order to increase the birefringence control and film strength of the film.
In the relationship between the birefringence (Δn (S)) and the draw ratio (S) when the block copolymer of the present invention is stretched, a resin whose slope K obtained from the least square approximation satisfies the following equation is used. It is preferable.
K = Δn (S) / S
−2.0 × 10 ⁻⁵ <K <2.0 × 10 ⁻⁵
Here, the value of K is the glass transition temperature (Tg) measured by DSC measurement of the polymer, measured at a stretching temperature of Tg ± 10 ° C., and 5% / min. It is a value when extending | stretching at the extending | stretching speed of. However, when the block copolymer had two or more Tg, the highest Tg was used.

A more preferable range of the value of K is −1.2 × 10 ⁻⁵ <K <1.2 × 10 ⁻⁵ , and a particularly preferable range is −1.0 × 10 ⁻⁵ <K <1.0 ×. 10 ⁻⁵ . The value of the slope K represents the magnitude of the increase in birefringence (Δn (S)) with respect to the draw ratio (S). The larger the K, the larger the increase in birefringence with respect to the stretching, and the smaller the K, the birefringence with respect to stretching. The amount of increase is small. For example, when used for a retardation film such as a quarter-wave plate, a material having a K value in this range is preferable because the change in birefringence due to stretching or orientation is small, and the required birefringence design is easy. Moreover, when using for a polarizing plate protective film etc., the material whose K value is in this range is preferable because birefringence due to orientation due to molding in extrusion molding or cast molding is less likely to occur. Furthermore, when a birefringence distribution occurs in the optical film surface after stretching, a material having a K value in this range is preferable as an optical film because the birefringence distribution in the film surface can be kept small.

In recent years, as a liquid crystal display becomes larger and a polymer optical film necessary for it becomes larger, a material having a small change in birefringence due to strain is required in order to reduce the distribution of birefringence caused by bias of external force. . The closer the value of the photoelastic coefficient is to zero, the smaller the change in birefringence due to external force, which means that the change in birefringence designed for each application is small. The photoelastic coefficient is described in various literatures (see, for example, Chemical Review No. 39.1998 (published by the Academic Publishing Center)), and is defined by the following equation.
CR = | Δn | / σR
| Δn | = | nx−ny |
(Where, CR: photoelastic coefficient, σR: stretching stress, | Δn |: absolute value of birefringence, nx: refractive index in the stretching direction, ny: refractive index perpendicular to the stretching direction)

The optical film comprising the block copolymer of the present invention has an effect that the photoelastic coefficient is small. The photoelastic coefficient is preferably 30 × 10 ⁻¹² Pa ⁻¹ or less, more preferably 20 × 10 ⁻¹² Pa ⁻¹ or less, more preferably 10 × 10 ⁻¹² Pa ⁻¹ or less in view of practicality. It is particularly preferred.
The retardation film in the present invention is a liquid crystal optical compensation such as a retardation plate such as a quarter-wave plate and a half-wave plate, and a viewing angle control film used in various liquid crystal modes such as TN, VA, IPS, and OCB. It is a film. The retardation film is designed to have a retardation of 10 nm to 300 nm depending on the requirement of the liquid crystal mode to be applied. The draw ratio is preferably 10% to 450% from the viewpoint of the uniformity of the retardation of the film. The block copolymer of the present invention can be widely used for optical compensation films of various liquid crystal modes depending on the design of its components.
The draw ratio (S) in the present invention is a value represented by the following equation, where L0 is the distance between chucks before stretching and L1 is the distance between chucks after stretching.

L1-L0
S = ――――――― × 100 (%)
L0

When the optical material of the present invention is used as a polarizing plate protective film, the retardation is stretched to be 0 nm to 10 nm.

When the retardation (Re) at the incident wavelength (λ) of the optical film of the present invention is Re (λ), the relationship between the wavelength λ and Re (λ) / Re (550) when the wavelength λ is 450 nm, 550 nm, and 650 nm, It is preferable for the optical film that the absolute value | L | of the slope L represented by the following formula obtained from the least square approximation is small.
L = [(Re (λ) / Re (550))] / λ
When a non-hydrogenated block copolymer and a block copolymer hydrogenated only with an olefinically unsaturated double bond in the present invention are stretched, a value of | L | equal to or lower than that of a polycarbonate generally used as an optical film And can be preferably used as an optical film. In addition, a block copolymer obtained by hydrogenating both an olefinically unsaturated double bond and an unsaturated double bond of an aromatic ring shows a value smaller than the value of | L | of polycarbonate and is more preferably used as an optical film. Can do. The value of the slope L represents a change of retardation (Re (λ) / Re (550)) with respect to the wavelength λ with respect to the retardation of 550 nm. The fact that the absolute value | L | of the inclination L is small means that there is little change in retardation due to the wavelength of incident light, and when it is used in a display device or the like, when | L | It is possible to suppress the decrease.

  Moreover, in this invention, polymers other than a block copolymer can be mixed in the range which does not impair the objective of this invention. Examples of the polymer other than the block copolymer of the present invention include polyolefin resins such as polyethylene, polypropylene, and polybutene, polystyrene, rubber-modified high impact polystyrene (HIPS), styrene-butyl acrylate copolymer, styrene-acrylonitrile copolymer. Polymer, styrene-maleic anhydride copolymer, acrylonitrile-butadiene-styrene copolymer (ABS), methacrylate ester-butadiene-styrene copolymer (MBS), polyvinyl chloride resin, polymethacrylate ester resin, Polycarbonate resins, polyethylene resins such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyamide resins, polyphenylene sulfide resins, polyether ether ketone resins , Thermoplastic resins such as polysulfone resin, polyphenylene oxide resin, polyimide resin, polyetherimide resin, polyacetal resin, cyclic olefin resin, norbornene resin, and phenol resin, melamine resin, silicone resin, epoxy resin At least one kind such as a thermosetting resin can be further added.

  The norbornene resin is composed of a repeating unit of a norbornene skeleton or a copolymer of a norbornene skeleton and a methylene skeleton. Examples of the norbornene-based resin include “Arton” manufactured by JSR, “Zeonex” and “Zeonor” manufactured by Zeon Corporation, “Appel” manufactured by Mitsui Chemicals, and “Topas” manufactured by Chicona. Specific examples include JP-A-62-252406, JP-A-62-2252407, JP-A-2-133413, JP-A-63-145324, JP-A-63-264626, Japanese Laid-Open Patent Publication No. 1-2240517, Japanese Patent Publication No. 57-8815, Japanese Laid-Open Patent Publication No. 5-39403, Japanese Laid-Open Patent Publication No. 5-43663, Japanese Laid-Open Patent Publication No. 5-43834, Japanese Laid-Open Patent Publication No. 5-70655, Japanese Laid-open Patent Publication No. -279554, JP-A-6-206985, JP-A-7-62028, JP-A-8-176411, JP-A-9-241484, and the like.

  Furthermore, arbitrary additives can be blended in accordance with various purposes within a range that does not significantly impair the effects of the present invention. The type of additive is not particularly limited as long as it is generally used for blending resins and rubber-like polymers. Inorganic fillers, pigments such as iron oxide, stearic acid, behenic acid, zinc stearate, calcium stearate, magnesium stearate, ethylene bisstearamide, lubricants, mold release agents, paraffinic process oil, naphthenic process oil, Softeners and plasticizers such as aromatic process oil, paraffin, organic polysiloxane, mineral oil, hindered phenol antioxidants, antioxidants such as phosphorus heat stabilizers, hindered amine light stabilizers, benzotriazoles Examples include ultraviolet absorbers, flame retardants, antistatic agents, reinforcing agents such as organic fibers, glass fibers, carbon fibers, and metal whiskers, coloring agents, other additives, and mixtures thereof.

The manufacturing method of the optical film in the present invention is not particularly limited, and a known method can be used. For example, it can be produced using a melt kneader such as a single screw extruder, a twin screw extruder, a Banbury mixer, a Brabender, or various kneaders. In addition, the film in the present invention can be formed by a known method such as injection molding, sheet molding, blow molding, injection blow molding, inflation molding, extrusion molding, foam molding, and the like. Sub-processing molding methods can also be used.
As a preferable method for producing the optical film of the present invention, techniques such as extrusion molding and cast molding are used. For example, an unstretched film can be extruded by using an extruder equipped with a T die, a circular die, or the like. In addition, the film can be cast-molded by dissolving the block copolymer using a solvent in which the block copolymer is soluble, for example, a solvent such as chloroform or toluene, and then solidifying by casting and solidifying.

The film obtained by the above method can further be longitudinally uniaxially stretched in the mechanical flow direction and transversely uniaxially stretched in the direction perpendicular to the mechanical flow direction. Also, a sequential biaxial stretching method of roll stretching and tenter stretching, tenter A biaxially stretched film can be produced by stretching by a simultaneous biaxial stretching method by stretching, a biaxial stretching method by tubular stretching, or the like. By stretching, the strength of the film can be improved. The final draw ratio can be determined from the heat shrinkage rate of the obtained film.
In the present invention, the thickness of the optical film is preferably in the range of 1 to 300 μm, more preferably in the range of 5 to 200 μm, and particularly preferably in the range of 10 to 100 μm.

  The optical film of the present invention is a polarizing plate protective film, a quarter-wave plate, a half-wave plate, etc. used for a display such as a liquid crystal display, a plasma display, an organic EL display, a field emission display, and a rear projection television. It can be suitably used for a plate, a liquid crystal optical compensation film such as a viewing angle control film, a display front plate, a display substrate, a lens, and a transparent substrate used for solar cells. The optical film of the present invention can be subjected to surface functionalization treatment such as antireflection treatment, transparent conductive treatment, electromagnetic wave shielding treatment, and gas barrier treatment.

Next, the present invention will be described by way of examples.
First, the evaluation methods used in the present invention and examples will be described.
(A) Evaluation (1) Measurement of Retardation Using a RETS-100 manufactured by Otsuka Electronics Co., Ltd., a wavelength of 400 to 800 nm was measured by a rotary analyzer method. The absolute value of birefringence (| Δn |) and retardation (Re) have the following relationship.
Re = | Δn | × d
(| Δn |: absolute value of birefringence, Re: retardation, d: thickness of sample)
The absolute value (| Δn |) of birefringence is a value shown below.
| Δn | = | nx−ny |
(Nx: refractive index in the stretching direction, ny: refractive index perpendicular to the stretching direction in the plane)

(2) Measurement of birefringence Measurement was performed by a rotating analyzer method using RETS-100 manufactured by Otsuka Electronics. The value of birefringence is a value of 550 nm. Birefringence (Δn) was calculated by the following formula.
Δn = nx−ny
(Δn: birefringence, nx: refractive index in the stretching direction, ny: refractive index perpendicular to the stretching direction)
The absolute value (| Δn |) of birefringence (Δn) was determined as follows.
| Δn | = | nx−ny |

(3) Measurement of photoelastic coefficient
A birefringence measuring apparatus described in detail in Polymer Engineering and Science 1999, 39, 2349-2357 was used. A film tensioning device was placed in the laser beam path, and birefringence was measured while applying a tensile stress at 23 ° C. The strain rate during stretching was 50% / min (between chucks: 10 mm, chuck moving speed: 5 mm / min), and the test piece width was 8 mm. From the relationship between the absolute value of birefringence (| Δn |) and the extensional stress (σR), the photoelastic coefficient (CR) was calculated by determining the slope of the straight line by least square approximation. For the calculation, data with an extensional stress between 2.5 MPa ≦ σR ≦ 10 MPa was used.
CR = | Δn | / σR
| Δn | = nx−ny
(CR: photoelastic coefficient, σR: stretching stress, | Δn |: absolute value of birefringence, nx: refractive index in the stretching direction, ny: refractive index perpendicular to the stretching direction)

(4) Block ratio A method of oxidatively decomposing a block copolymer with di-tertiary butyl hydroperoxide using osmium tetroxide as a catalyst [I. M.M. KOLTHOFF, et al. , J .; Polym. Sci. 1,429 (1946)] was quantified and determined from the following formula.

Vinyl aromatic of block copolymer
Mass% of hydrocarbon polymer block
Block ratio (mass%) = ――――――――――――――――― × 100
All vinyl block copolymer
% By mass of aromatic hydrocarbon

The block ratio of the hydrogenated block copolymer was analyzed using the polymer before hydrogenation.

(5) Measurement of hydrogenation rate The hydrogenation rate of the olefinically unsaturated double bond of the entire block copolymer and the unsaturated double bond of the aromatic ring of the vinyl aromatic compound was determined by using DPX400 manufactured by Bruker. Nuclear magnetic resonance spectrum (NMR) measurement was performed, and the hydrogenation rate (%) was determined by assigning each peak. Deuterated chloroform or o-dichlorobenzene-d4 was used as a measurement solvent. The hydrogenation rate for each block was determined as follows. The hydrogenation rate of the olefinically unsaturated double bond in the entire block copolymer is H _D , the hydrogenation rate of the olefinically unsaturated double bond in the polymer block A is H _DA , and the olefinic property in the polymer block B The hydrogenation rate of the unsaturated double bond is H _DB , the hydrogenation rate of the unsaturated double bond of the aromatic ring of the vinyl aromatic compound in the entire block copolymer is H _R , and the vinyl aromatic compound in the polymer block A The hydrogenation rate of the unsaturated double bond of the aromatic ring is H _RA , and the hydrogenation rate of the unsaturated double bond of the aromatic ring of the vinyl aromatic compound in the polymer block B is H _RB . The hydrogenation rate H _DB of the olefinically unsaturated double bond in the polymer block B is determined by considering that the reactivity of hydrogenation is different between the blocks A and B, and the case where H _DA is maximum and H _DB There the assumption that the maximum, conjugated diene composition ratio of H _D and each block was calculated range of H _DB. Not contain a conjugated diene in the polymer block A, H _DB is equal to H _D. In addition, the hydrogenation rate _HRA of the aromatic double unsaturated double bond of the vinyl aromatic compound in the polymer block A is the highest in _HRB , considering that the hydrogenation reactivity is different between the blocks A and B. and if it _is, the assumption that _{H RA} is the maximum, a vinyl aromatic hydrocarbon composition ratio of H _R and each block was calculated range of H _RA. If in the polymer block B does not contain a vinyl aromatic hydrocarbon, H _RA is equal to H _R.

(B) Used raw materials, etc. (1) Block copolymer (A-1)
Using an autoclave with a stirrer, 0.080 parts by mass of n-butyllithium was added to a cyclohexane solution containing 25 parts by mass of styrene under a nitrogen gas atmosphere, and polymerization was performed at 80 ° C. for 20 minutes. Next, a cyclohexane solution containing 15 parts by mass of styrene and 24 parts by mass of 1,3-butadiene was continuously added for 60 minutes to polymerize at 80 ° C. Next, a cyclohexane solution containing 36 parts by mass of styrene was continuously added for 25 minutes and polymerized at 80 ° C., and then held at 80 ° C. for 10 minutes. Thereafter, the polymerization was stopped by adding methanol to the polymerization vessel at a 0.9-fold mole relative to n-butyllithium, and 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) was used as a stabilizer. ) Ethyl] -4,6-di-t-pentylphenyl acrylate is added in an amount of 0.5 parts by mass to 100 parts by mass of the block copolymer, and then the solvent is removed to obtain the block copolymer (A-1) Obtained. The block copolymer A-1 is a polymer block A in which styrene / 1,3-butadiene = 100/0 mass ratio, and a polymer in which styrene / 1,3-butadiene = 38.5 / 61.5 mass ratio. This is an ABA block polymer composed of polymer block A in which block B and styrene / 1,3-butadiene = 100/0 mass ratio. The obtained block copolymer A-1 has a number average molecular weight of 85,000, a styrene content of 77.5%, a block rate of 80% by mass, and a melt flow rate of 7 g / 10 min (according to ASTM D1238). , 200 ° C., load 5 kg).

(2) Diene hydrogenated block copolymer (A-2)
Using an autoclave with a stirrer, 0.15 parts by mass of n-butyllithium and 0.18 parts by mass of tetramethylethylenediaminetetraacetic acid are added to a cyclohexane solution containing 10 parts by mass of styrene under a nitrogen gas atmosphere, and the mixture is added at 75 ° C. for 5 minutes. Polymerization was carried out with continuous addition. Next, a cyclohexane solution containing 70 parts by mass of styrene and 10 parts by mass of 1,3-butadiene was continuously added for 60 minutes to polymerize at 75 ° C. Next, a cyclohexane solution containing 10 parts by mass of styrene was continuously added for 15 minutes and polymerized at 75 ° C., and then held at 75 ° C. for 10 minutes. Thereafter, the polymerization was stopped by adding methanol to the polymerization vessel at a 0.9-fold mole relative to n-butyllithium, and 2- [1- (2-hydroxy-3,5-di-t-pentylphenyl) was used as a stabilizer. ) Ethyl] -4,6-di-t-pentylphenyl acrylate, after adding 0.5 parts by mass to 100 parts by mass of the block copolymer, the solvent is removed to obtain a cyclohexane solution of the block copolymer P-1. Got. The block copolymer P-1 is a polymer block A having a styrene / 1,3-butadiene = 100/0 mass ratio, and a polymer having a styrene / 1,3-butadiene = 87.5 / 12.5 mass ratio. It is an AAA type block polymer which consists of polymer block A which is block A and styrene / 1,3-butadiene = 100/0 mass ratio. In addition, the obtained block copolymer P-1 had a number average molecular weight of 120,000 and a styrene content of 90% by mass.

Next, using this copolymer P-1 as a starting material, a diene hydrogenated block copolymer A-2 was obtained. The hydrogenation catalyst was prepared by adding 1 liter of dried and purified cyclohexane to a nitrogen-substituted reaction vessel, adding 100 mmol of bis (η5-cyclopentadienyl) titanium dichloride, and containing 200 mmol of trimethylaluminum with sufficient stirring. -A hydrogenation catalyst was used, which was reacted for about 3 days at room temperature after adding a hexane solution. A hydrogenation catalyst was added at 100 ppm as titanium per 100 parts by mass of the block copolymer, and a hydrogenation reaction was carried out at a hydrogen pressure of 0.7 MPa and a temperature of 65 ° C. Thereafter, methanol was added and the solvent was removed to obtain a hydrogenated block copolymer. The hydrogenation rate of the block copolymer hydrogenated product was adjusted by the amount of hydrogen. The hydrogenation rate of the copolymer A-2 _{is, H DB} is _{99.9%, H RA} is 0%, _{H D} is 99.9%, _{H R} was 0%.

(3) Diene and aromatic ring hydrogenated block copolymer (A-3)
Using an autoclave with a stirrer, 0.065 part of n-butyllithium was added to a cyclohexane solution containing 25 parts by weight of styrene under a nitrogen gas atmosphere, and polymerization was performed at 70 ° C. for 20 minutes. Next, a cyclohexane solution containing 20 parts by mass of styrene and 30 parts by mass of 1,3-butadiene was continuously added for 60 minutes to perform polymerization at 70 ° C. Next, a cyclohexane solution containing 25 parts by mass of styrene was continuously added for 60 minutes and polymerized at about 70 ° C., and then held at 70 ° C. for 10 minutes. Thereafter, methanol was added to the polymerization vessel at a 0.9-fold molar ratio with respect to n-butyllithium to stop the polymerization, and 2- [1- (2-hydroxy-3,5-di-t- Pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate is added to 0.5 parts by mass with respect to 100 parts by mass of the block copolymer composition, and then the solvent is removed to remove block copolymer. Combined P-2 was obtained. The block copolymer P-2 is a polymer block A in which styrene / 1,3-butadiene = 100/0 mass ratio, and a polymer in which styrene / 1,3-butadiene = 40.0 / 60.0 mass ratio. This is an ABA block polymer composed of polymer block A in which block B and styrene / 1,3-butadiene = 100/0 mass ratio. The resulting block copolymer P-2 has a number average molecular weight of 110000, a styrene content of 70%, a block rate of 55%, and a melt flow rate of 6 g / 10 min (according to ASTM D1238, 200 ° C. The load was 5 kg).

Next, 800 g of cyclohexane purified with 200 g of this block copolymer P-2 was transferred to a 5 L high-pressure reactor, and 10 g of Raney Ni was transferred using 1000 g of cyclohexane. The inside of the reactor was replaced with hydrogen, and hydrogenation reaction was performed at 8 MPa and 160 ° C. for 6 hours to obtain a diene and aromatic ring hydrogenated block copolymer A-3. Hydrogenation was determined from 1H-NMR. The DSC of this hydride was measured to confirm a single Tg. The hydrogenation rate of the copolymer A-3 _{is, H DB} is _{99.9%, H RA} is 99.4~100%, _{H D} is 99.9%, _{H R} was 99.6%.

(4) Polycarbonate resin (B-1)
As the polycarbonate resin used for comparison, a polycarbonate resin having a melt flow rate of 10 g / 10 min (according to ASTM D1238, 300 ° C., load 1.2 kg) was used.

[Examples 1 to 9 and Comparative Examples 1 to 3]
Block copolymer (A-1) and diene hydrogenated block copolymer (A-2) on the hopper of Technobel's T-die mounting extruder (KZW15TW-25MG-NH type / width 150 mmT die mounting / lip thickness 0.5 mm) ), A pellet of either diene and aromatic ring hydrogenated block copolymer (A-3) or polycarbonate resin (B-1). By adjusting the resin temperature in the cylinder of the extruder and the temperature of the T-die and performing extrusion molding, uniaxial stretching (stretching speed 5% / min) of the obtained unstretched film was performed using a tensile tester. 9. Unstretched films of Comparative Examples 1 to 3 were obtained. Nx necessary for obtaining | Δn | = | nx−ny | is a refractive index in a uniaxial tensile direction, and ny is a refractive index in a direction perpendicular to the uniaxial tensile direction. Tables 1 and 2 show the composition, extrusion conditions, stretching conditions, film thickness, retardation wavelength dependency (450 nm, 550 nm, 650 nm), absolute value of birefringence, and photoelastic coefficient. Tables 1 and 2 show the absolute value | L | of the slope L obtained from the least square approximation based on the relationship between the wavelength λ and Re (λ) / Re (550) when the wavelength λ is 450 nm, 550 nm, and 650 nm. Further, the relationship between birefringence (Δn (S)) and stretch ratio (S) obtained from the results of Tables 1 and 2 was plotted, and the value of K was obtained by least square approximation. The results are shown in Table 3. A graph showing the relationship between birefringence (Δn (S)) and draw ratio (S) is shown in FIG.

[Examples 10 to 12]
An unstretched film was formed by the same method as in Example 1, and this unstretched film was uniaxially stretched by the same method as in Example 1 to finely adjust the temperature, whereby a film having a retardation of 138 nm was obtained. Obtained. Table 4 shows the composition, extrusion conditions, stretching conditions, film thickness, and retardation. It was confirmed that it functions as a retardation film having retardation as a quarter wavelength plate at 550 nm.

[Examples 13 to 15]
An unstretched film was formed by the same method as in Example 1, and this unstretched film was uniaxially stretched by the same method as in Example 1 to finely adjust the temperature, whereby a film having a retardation of 275 nm was obtained. Obtained. Table 4 shows the composition, extrusion conditions, stretching conditions, film thickness, and retardation. It was confirmed that it functions as a retardation film having retardation as a half-wave plate at 550 nm.

  The optical film of the present invention has excellent optical characteristics that it is transparent and has little change in birefringence due to stretching, and the optical film of the present invention is a liquid crystal display, plasma display, organic EL display, field emission display, rear projection television. Polarizing plate protective film used for displays such as, 1/4 wave plate, retardation plate such as 1/2 wave plate, liquid crystal optical compensation film such as viewing angle control film, display front plate, display substrate, lens, etc. It can be suitably used for transparent substrates used in solar cells.

The graph which shows the relationship of birefringence ((DELTA) n (S)) at the time of extending | stretching of an Example and a comparative example, and a draw ratio (S).

Claims (19)

  An optical film comprising a block copolymer comprising a polymer block A mainly composed of at least one vinyl aromatic hydrocarbon and a polymer block B mainly composed of at least one conjugated diene.   An optical film comprising a block copolymer having at least two polymer blocks A and at least one of the polymer blocks A containing a conjugated diene.   The optical film according to claim 1, comprising a block copolymer having a vinyl aromatic hydrocarbon content of 45 to 99% by mass.   The optical film according to claim 2, comprising a block copolymer having a vinyl aromatic hydrocarbon content of 55 to 99 mass%.   The optical film according to any one of claims 1 to 4, wherein the optical film comprises a block copolymer containing 1,3-butadiene as a conjugated diene.   The olefinically unsaturated double bond in the polymer block B is composed of a block copolymer hydrogenated by 5 to 100%, according to any one of claims 1, 3, 4, and 5. Optical film.   The unsaturated double bond of the aromatic ring of the vinyl aromatic compound in the polymer block A is composed of a block copolymer hydrogenated by 5 to 100%. The optical film described in 1.   The optical film according to any one of claims 1 to 5, wherein the olefinically unsaturated double bond of the entire block copolymer comprises a block copolymer hydrogenated by 5 to 100%.   The optical film according to any one of claims 1 to 5, wherein the olefinically unsaturated double bond of the entire block copolymer comprises a block copolymer hydrogenated by 85 to 100%.   10. The unsaturated double bond of the aromatic ring of the vinyl aromatic compound in the entire block copolymer is composed of a block copolymer hydrogenated by 5 to 100%. The optical film according to any one of the above.   The unsaturated double bond of the aromatic ring of the vinyl aromatic compound of the entire block copolymer is composed of a block copolymer hydrogenated by 85 to 100%. The optical film according to any one of the above.   Unsaturated double bond of aromatic ring of vinyl aromatic compound of whole block copolymer is hydrogenated by 90 to 100%, and olefinically unsaturated double bond of whole block copolymer is hydrogenated by 90 to 100% The optical film according to any one of claims 1 to 5, wherein the optical film is made of a block copolymer.   The optical film according to claim 1, wherein the optical film is stretched. In the relationship between the birefringence (Δn (S)) and the draw ratio (S) when the block copolymer is stretched, the value of the slope K obtained from the least square approximation satisfies the following formula: The optical film according to claim 1, wherein the optical film is a film.
K = Δn (S) / S
−2.0 × 10 ⁻⁵ <K <2.0 × 10 ⁻⁵   It is a film shape | molded by extrusion molding, The optical film of any one of Claims 1-14 characterized by the above-mentioned.   The optical film according to claim 1, wherein the optical film is a film formed by cast molding. A photoelastic coefficient is 30 * 10 <^-12> Pa < ^{-1 >} or less, The optical film of any one of Claims 1-16 characterized by the above-mentioned. A retardation film using the optical film according to claim 1, wherein the retardation is 10 nm to 300 nm, and the draw ratio is 10% to 450%.   Retardation is 0 nm-10 nm, The polarizing plate protective film which uses the optical film of any one of Claims 1-17 characterized by the above-mentioned.

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