JP2003255135A - Optical film and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film causing no leak of light as a protective film for a polarizing film, having high fracture strength even when the film is stretched by large magnification, and useful for a wide wavelength region as a quarter wavelength phase plate, and to provide a method for manufacturing the film. <P>SOLUTION: The film is obtained by melting and extruding an alicyclic structure-containing polymer containing 55 to 90 wt.% of a repeating unit having a bicyclo [3, 3, 0] octane structure, having 25,000 to 50,000 weight average molecular weight and 1.2 to 3.5 molecular weight distribution. When the thickness of the obtained film is measured at 100 points along each of the extruding direction and the direction perpendicular to that with 5 cm interval and 20 cm interval, respectively, the arithmetic averages AX and AY and the maximum absolute values Xmax and Ymax of the difference between each measured thickness and the averages are obtained. The proportion X(%) of Xmax to AX and the proportion Y(%) of Ymax to AY satisfy the relation of (1): X≤5 and Y≤5 or (2): X≤8 and Y≤8 and |X-Y|/ä(X+Y)/2}≤0.35. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical film obtained by melt-extruding an alicyclic structure-containing polymer and a method for producing the same, and more specifically, an optical film suitable as a protective film for a polarizing film and a phase plate. And the manufacturing method thereof.

[0002]

2. Description of the Related Art For display devices such as liquid crystal displays,
Phase plates, polarizing plates, liquid crystal cell substrates, etc. made of thermoplastic resin are used. As a phase plate, a base film such as polycarbonate is stretched to have retardation,
It is known that two or more of them are bonded together, and as a polarizing plate, one in which a protective film is laminated on the upper and lower surfaces of a polarizing film made of polyvinyl alcohol is known. With the increase in size and contrast of liquid crystal displays, the retardation values of the base film of the phase plate, the protective film of the polarizing film, the liquid crystal cell substrate, and the like are required to be uniform.

Japanese Unexamined Patent Publication (Kokai) No. 5-2108 discloses a phase plate having a birefringent layer having a film obtained by stretching and orientation of a thermoplastic saturated norbornene resin sheet formed by a melting method. It is described that it is preferable that the sheet before stretching has a uniform retardation value and the thickness unevenness (variation) is within ± 4% over the entire surface. However, although this film had a uniform retardation value, light leakage was not completely eliminated when it was used as a protective film for a polarizing film, for example.

[0004]

DISCLOSURE OF THE INVENTION The present invention has no leakage of light when used as a protective film for a polarizing film, has a large breaking strength even when stretched at a high magnification, and has a wide band as a quarter-wave phase plate. An object of the present invention is to provide an optical film that can be used in the wavelength range and a manufacturing method thereof.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that a specific amount of repeating units having a specific alicyclic structure is contained and the molecular weight and the molecular weight distribution are within a specific range. Using a resin that is, by melt-extrusion molding in a specific method, the thickness of each location of the film,
It was found that a film satisfying a specific relationship with the average value can be obtained. When this film is used, there is no light leakage when used as a protective film for a polarizing film, the breaking strength is large even when stretched to a high magnification, and it can be used as a quarter-wave phase plate in a wide wavelength range. It was found that a film can be obtained, and the present invention has been completed based on this finding.

Thus, according to the present invention: It contains 55 to 90% by weight of a repeating unit having a bicyclo [3.3.0] octane structure, has a weight average molecular weight of 25,000 to 50,000 and a molecular weight distribution of 1.
It is a film obtained by melt-extruding an alicyclic structure-containing polymer of 2 to 3.5, and the area of the film is 1 m ^2.
In the range of 5 cm in the flow direction at the time of molding, and 20 cm in the direction orthogonal to the flow at intervals of 100 cm, the arithmetic average value of the measured thickness values at 100 selected points is defined as A _X, and this average value A _X when and Xmax the largest of the absolute value of the difference between the measured value, the a _X of Xmax
And the ratio X (%) to 5 in the direction orthogonal to the flow during molding.
For the measured values of thickness at 100 selected points at intervals of 20 cm in the flow direction at intervals of 10 cm, the arithmetic mean value is defined as A _Y, and the absolute value of the difference between the mean value A _Y and the measured values is When the maximum is Ymax, Yma
An optical film characterized in that a ratio Y (%) of x to A _Y satisfies the following relationship: (1) X ≦ 5 and Y ≦ 5; or (2) X ≦ 8 and Y ≦ 8. And | X−Y | / {(X +
Y) / 2} ≦ 0.35

2. 2. The optical film as described in 1 above, which is a protective film for a polarizing film. 3. An optical film obtained by further stretching the optical film according to the above 1. 4. The optical film as described in 3 above, which is a phase plate. It contains 55 to 90% by weight of a repeating unit having a bicyclo [3.3.0] octane structure, has a weight average molecular weight of 25,000 to 50,000 and a molecular weight distribution of 1.
The alicyclic structure-containing polymer of 2 to 3.5 is melted, and the melt polymer is extruded into a film form from a die having a lip portion having a peel strength of 75 N or less with the melt polymer to form a film. 5c in the flow direction during molding within an area of 1 m ²
With respect to the measured values of the thickness at 100 selected points at intervals of 20 m in the direction orthogonal to the flow at an interval of m, the arithmetic average value is defined as A _X, and the absolute value of the difference between this average value A _X and the measured value. If the largest of these is Xmax, then X
The ratio X (%) of max to the above A _X and the arithmetic mean value of the measured thickness values at 100 selected points at intervals of 5 cm in the direction orthogonal to the flow at the time of molding and at intervals of 20 cm in the flow direction. A _Y, and when the maximum absolute value of the difference between the average value A _Y and the measured value is _Y max, the ratio Y (%) of Y max to A _Y satisfies the following relationship. (1) X ≦ 5 and Y ≦ 5, or (2) X ≦ 8 and Y ≦ 8 and | XY − / {(X +
Y) / 2} ≦ 0.35, respectively.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The optical film of the present invention has an area of 1 m ^{2 in} the film, and is 5 cm in the flow direction during molding.
At an interval of 20 cm in the direction orthogonal to the flow at an interval of, the arithmetic mean value of the thickness measurement values at 100 selected locations is defined as A _X, and the absolute value of the difference between the average value A _X and the measurement value is calculated. When the maximum one is Xmax, Xm
The ratio X (%) of ax to the above A _X and the arithmetic mean value of the measured values of the thickness at 100 selected points at intervals of 5 cm in the direction orthogonal to the flow at the time of molding and at intervals of 20 cm in the flow direction. A _Y, and when the maximum absolute value of the difference between the average value A _Y and the measured value is _Y max, the ratio Y (%) of Y max to A _Y satisfies the following relationship. Is characterized by. (1) X ≦ 5 and Y ≦ 5, or (2) X ≦ 8 and Y ≦ 8 and | X−Y | / {(X +
Y) / 2} ≦ 0.35 The film has the above X, Y and | X−Y | / {(X + Y).
When the value of / 2} satisfies the above range, there is no light leakage when used as a protective film for a polarizing film, and the breaking strength increases even when stretched at a high magnification. In the present invention, the thickness of the film is measured with a measuring device that sandwiches the film from both sides and detects the distance. The pressure for sandwiching the film in the above thickness measuring machine is preferably in the range of 0.005 to 0.014N. When the pressure for sandwiching the film is less than 0.005N, the thickness is measured larger than it actually is when the film has small waviness or warpage. When it exceeds 0.014N, the film is deformed and the thickness is increased. Measured smaller than it really is. Therefore, if the pressure between the films of the measuring machine is in the above range, the thickness measurement accuracy is improved.

In the present invention, the material of the film contains 55 to 90% by weight of a repeating unit having a bicyclo [3.3.0] octane structure and has a weight average molecular weight of 25,
000 to 50,000 and a molecular weight distribution of 1.2 to
An alicyclic structure-containing polymer of 3.5 is used. The alicyclic structure-containing polymer contains an alicyclic structure in the repeating unit of the polymer, and the alicyclic structure may be in either the main chain or the side chain. Examples of the alicyclic structure include a cycloalkane structure and a cycloalkene structure, and the cycloalkane structure is preferable from the viewpoint of thermal stability and the like. The alicyclic structure-containing polymer generally includes a monomer having a norbornene ring structure (norbornene-based monomer), a monocyclic olefin, a cyclic conjugated diene, a vinyl aromatic compound, a vinyl alicyclic hydrocarbon compound, and other monomers. ,
It can be obtained by polymerizing by a known polymerization method such as metathesis ring-opening polymerization or addition polymerization, and hydrogenating a carbon-carbon unsaturated bond if necessary.

In the present invention, the repeating unit having a bicyclo [3.3.0] octane structure in the alicyclic structure-containing resin is 55 to 90% by weight, preferably 60 to 90% by weight.
The one containing 85% by weight is used. Bicyclo [3.3.
[0] By using the alicyclic structure-containing polymer in which the content of the repeating unit having an [0] octane structure is within the above range, light leakage due to variation in retardation does not occur, and the polymer is stretched at a high magnification for use. The breaking strength does not decrease, and a film having no variation in retardation can be obtained. In order to adjust the content of the repeating unit having a bicyclo [3.3.0] octane structure in the alicyclic structure-containing polymer to the above range, a norbornene-based monomer having a structure in which a five-membered ring is bonded to a norbornene ring is used. In a total content of 55 to 90
After the monomer mixture containing 60% by weight to 60% by weight, preferably 60 to 85% by weight, is polymerized by a known metathesis ring-opening polymerization method, the carbon-carbon unsaturated bond of the ring is hydrogenated by a known method. Examples of the norbornene-based monomer having a structure in which a five-membered ring is bonded to the norbornene ring include tricyclo [4.
3.1 ^2,5 . 0 ^1,6 ] -deca-3,7-diene (common name dicyclopentadiene) and its derivatives (having a substituent on the ring), tetracyclo [7.4.1]
^10,13 . 0 ^1,9 . 0 ^2,7 ] -Trideca-2,
4,6--11-tetraene (1,4-methano-1,4,
Also referred to as 4a, 9a-tetrahydrofluorene: the common name methanotetrahydrofluorene) and its derivatives. These monomers may be used alone or in combination. In the present invention, a norbornene-based monomer having a structure in which a five-membered ring is bonded to the norbornene ring is added to another monomer copolymerizable with them.
Ring-opening copolymerization can be performed. As the copolymerizable monomer, bicyclo [2.2.1] - hept-2-ene (common name: norbornene) and derivatives thereof, tetracyclo ^{[4.4.1 2,5.} 1 ^{7, 10} . 0] -Dodeca-3
-Norbornene monomers such as ene (common name: tetracyclododecene) and its derivatives; monocyclic olefins such as cyclohexene, cycloheptene, cyclooctene and their derivatives; cyclic conjugated dienes such as cycloheptadiene and cyclohexadiene and their derivatives ; And the like.

The above-mentioned monomers are, for example, ruthenium,
A catalyst comprising a metal halide such as osmium, a nitrate or an acetylacetone compound, and a reducing agent; or a catalyst comprising a metal halide such as titanium, zirconium, tungsten, molybdenum or an acetylacetone compound and an organoaluminum compound; Used for metathesis ring-opening polymerization. The obtained ring-opening polymer hydrogenates carbon-carbon unsaturated bonds preferably 90% or more by a known hydrogenation catalyst containing a transition metal such as nickel or palladium.

The alicyclic structure-containing polymer used in the present invention is
Polyisoprene or polystyrene-converted weight average molecular weight (Mw) measured by gel permeation chromatography of a cyclohexane solution (toluene solution when the polymer resin is not dissolved) is 25,000 to 50,
000, preferably 30,000 to 45,000, and the molecular weight distribution (Mw / Mn) is 1.2 to 3.5, preferably 1.5 to 3.0. By setting Mw and Mw / Mn within the above ranges, there is no light leakage due to variation in retardation, and even when stretched to a high ratio, the breaking strength does not decrease and variation in retardation does not occur. A film is obtained. Also, the glass transition temperature (T
g) is preferably 80 to 170 ° C. Within this range, heat resistance and molding processability are highly balanced, which is preferable.

The optical film of the present invention has the alicyclic structure described above.
Peeling the contained polymer from the molten alicyclic structure-containing polymer
Uses a T-die with a lip that has a peel strength of 75N or less
It is obtained by melt extrusion molding. Conditions for melt extrusion
Is appropriately selected according to the purpose of use, but the cylinder temperature
However, it is preferable that the temperature is within the range of 200 to 300 ° C.
The temperature of the pool is appropriately set within the range of 80 to 160 ° C.
In melt extrusion molding, the extrusion extruded from the extruder
The above resin melted in the form of a sheet is used for the first roll and the second roll.
And 3 rolls of the 3rd roll are sequentially inscribed and transferred.
Method [manufacturing method (1)] or extruded from an extruder
The sheet-shaped molten thermoplastic resin prepared by
It is rolled by passing through the gap between the two rolls of the second roll.
Obtained sheet-like molten thermoplastic resin,
Next, apply the molten thermoplastic resin directly to the second roll.
A method of transferring by sequentially contacting the third roll of the third roll
[Manufacturing method (2)] and the like can be adopted. So
Then, no matter which method is used, The resin contact time on the first roll is t (seconds), the first roll
The resin temperature when leaving the₁(℃), glass transfer of resin
When the transfer temperature is Tg (° C), t × (Tg-T ₁)
To be in the range of -50 to +20 (sec / ° C)
Preferably, The peripheral speed of the second roll at the peripheral speed R3 of the third roll
Ratio R3 / R2 to degree R2 is less than 0.999, 0.9
It is preferable to set it to 90 or more, Temperature T of the third roll_R3(℃) and on the third roll
Temperature T of the sheet-shaped thermoplastic resin at the time of contact_S(℃)
So that and satisfy the relation expressed by the following inequality (I).
Preferably.               T_S-10 ° C ≦ T_R3≤T_S+ 10 ° C (I) Film obtained by following the above steps
And the above X and Y values of | X−Y | / {(X + Y) /
The values of 2} are all smaller.

The optical film of the present invention is 0.005
The thickness measured by sandwiching the film with a force of 0.014 N is
Preferably 20-300 μm, more preferably 50-2
And the retardation value is preferably 5n.
m or less and the variation in retardation is ± 1.5.
nm or less, and the water absorption rate is preferably 0.05% or less. The optical film of the present invention is a polarizing plate protective film,
Liquid crystal cell substrate, antireflection film, transparent conductive film,
It can be suitably used for an electroluminescence (EL) substrate, an EL protective film, a light diffusion film, a light condensing sheet and the like. Further, when stretched, it can be suitably used as a retardation film. When the glass transition temperature of the alicyclic structure-containing polymer to be used is Tg, the film is stretched preferably in the temperature range of (Tg-30) ° C to (Tg + 60) ° C, more preferably (Tg-
10) C. to (Tg + 50) C in the temperature range, at least in one direction, preferably at a draw ratio of 1.01 to 2 times.

[0015]

EXAMPLES The present invention will be described more specifically below with reference to production examples, examples and comparative examples. [Parts] and [%] in these examples are based on weight unless otherwise specified. However, the present invention is not limited to these production examples and examples.

Various physical properties were measured according to the following methods. (1) Molecular weight Cyclohexane (toluene when the resin does not dissolve) is used as a solvent and measured by GPC to obtain a weight average molecular weight (Mw) in terms of standard polystyrene. (2) Molecular weight distribution Cyclohexane (toluene when the resin does not dissolve) was used as a solvent and measured by GPC to obtain a standard polystyrene-equivalent weight average molecular weight (Mw) and number average molecular weight (Mn),
The ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) is calculated. (3) Glass transition temperature (Tg) Measured by DSC based on JIS K7121. (4) Hydrogenation rate The hydrogenation rates of the main chain and aromatic ring of the polymer were measured by ¹ H-NMR.
Is calculated and calculated.

(5) The thickness of the film is measured using a linear gauge (VL-50 manufactured by Mitutoyo Corporation). The film is placed on a stage with a smooth surface, and the film is sandwiched between the stage surface and the pin by pressing the measurement point on the opposite surface of the surface facing the stage with a pin, and the distance between the stage surface and the pin tip is Measured as thickness. The pressure to sandwich the film is adjusted to 0.01N. The thickness is 1 m ^{2 of} the film area (100 cm × 10
0 cm), at an interval of 5 cm in the flow direction at the time of molding, and at an interval of 20 cm in the direction orthogonal to the flow, the arithmetic mean value of the thickness measurement values at 100 selected points is defined as A _X, and this average value When the maximum absolute value of the difference between A _X and the measured value is Xmax, the ratio of Xmax to A _X is X (%), and at a distance of 5 cm in the direction orthogonal to the flow during molding, Regarding the measured values of thickness at 100 selected points at intervals of 20 cm in the flow direction, the arithmetic average value is defined as A _Y, and the maximum absolute value of the difference between the average value A _Y and the measured value is Ymax. when the, the ratio of the _{a Y} of Ymax was Y (%). The thickness measurement accuracy is 0.1 μm.

(6) Retardation average value (Re)
And its variation COBRA-21ADH manufactured by Oji Scientific Instruments Co., Ltd. is used, within a film area of 1 m ² (100 cm × 100 cm), at intervals of 5 cm in the flow direction at the time of molding, and at intervals of 5 cm in the direction orthogonal to the flow. at 100 points which is, retardation value at a wavelength of 548nm for (Re), and the arithmetic mean value _{a R,} Remax the largest of the absolute value of the difference between the measured values and the average value _{a R}
When a was calculated the ratio of the _{A R} of Remax. (7) Stretching processability is 10 from the glass transition temperature of the polymer using a biaxial stretching tester manufactured by Toyo Seiki Co., Ltd.
The film was stretched uniaxially in parallel with the flow direction of melt extrusion at a temperature higher by 0 ° C., and the stretching ratio at break was 1.5 times or more was marked with ◯, and less than 1.5 times was marked with x.

[Production Example 1] 1.2 parts of 1-hexene, 0.15 parts of dibutyl ether, and 0.30 parts of triisobutylaluminum were placed in a reactor at room temperature and mixed with 500 parts of dehydrated cyclohexane under a nitrogen atmosphere. after maintaining at 45 ° C., tricyclo [4.3.0.1 ^{2, 5]} deca-3,7-diene (dicyclopentadiene, hereinafter, DC
Abbreviated as P) 20 parts, 1,4-methano-1,4,4a, 9
a-Tetrahydrofluorene (hereinafter abbreviated as MTF) 1
40 parts, and 8-methyl-tetracyclo [4.4.0.
1 ^{2, 5} . 1 ^7,10 ] -dodeca-3-ene (hereinafter, M
Abbreviated as TD) 40 parts of norbornene-based monomer mixture and tungsten hexachloride (0.7% toluene solution)
40 parts and 40 parts were continuously added and polymerized over 2 hours. 1.06 parts of butyl glycidyl ether and 0.52 parts of isopropyl alcohol were added to the polymerization solution to inactivate the polymerization catalyst to stop the polymerization reaction.

Then, to 100 parts of the reaction solution containing the obtained ring-opening polymer, 270 parts of cyclohexane was added, and further 5 parts of a nickel-alumina catalyst (manufactured by JGC Chemical Co., Ltd.) as a hydrogenation catalyst was added, and hydrogen was added. Then, the pressure was increased to 5 MPa with stirring, and the mixture was heated to a temperature of 200 ° C. with stirring and then reacted for 4 hours to obtain a reaction solution containing 20% of hydrogenated DCP / MTF / MTD ring-opening polymer. After removing the hydrogenation catalyst by filtration, a soft polymer (Kuraray Co .; Septon 2002) and an antioxidant (Ciba Specialty Chemicals Co .; Irganox 1010) were added to each of the obtained solutions and dissolved. (All are 0.1 parts per 100 parts of polymer). Then, the solvent cyclohexane and other volatile components are removed from the solution by using a cylindrical concentrating dryer (manufactured by Hitachi, Ltd.), and the hydrogenated polymer is extruded in a strand form from the extruder in a molten state, and cooled and pelletized. It was converted to and collected. The copolymerization ratio of each norbornene-based monomer in the polymer was calculated from the composition of the residual norbornenes in the solution after polymerization (by the gas chromatography method). DCP / MTF / MTD =
On 10/70/20, it was almost equal to the composition. The weight average molecular weight (Mw) of this hydrogenated ring-opening polymer was 3
The molecular weight distribution (Mw / Mn) was 1,000, the hydrogenation rate was 99.9%, and the Tg was 134 ° C.

[Production Example 2] Instead of the norbornene-based monomer mixture consisting of DCP, MTF and MTD, MT
A ring-opened polymer hydrogenated product was produced in the same manner as in Production Example 1 except that a norbornene-based monomer mixture consisting of F 160 parts and MTD 40 parts was used and the amount of 1-hexene was changed to 1.0 part. The copolymerization ratio of each norbornene-based monomer in the obtained hydrogenated product of the ring-opening polymer was MTF / MTD = 80 /
20, the weight average molecular weight (Mw) is 34,000, the molecular weight distribution (Mw / Mn) is 1.7, and the hydrogenation rate is 99.9.
%, Tg was 136 ° C.

[Production Example 3] DC was used instead of the norbornene-based monomer mixture consisting of DCP, MTF and MTD.
A ring-opened polymer hydrogenated product was produced in the same manner as in Production Example 1 except that a norbornene-based monomer mixture consisting of 160 parts of P and 40 parts of MTD was used and the amount of 1-hexene was changed to 1.0 part. The copolymerization ratio of each norbornene-based monomer in the obtained ring-opened polymer hydrogenated product was DCP / MTD = 80 /
20, weight average molecular weight (Mw) is 43,000, molecular weight distribution (Mw / Mn) is 3.0, hydrogenation rate is 99.9.
%, Tg was 110 ° C.

[Example 1] The pellets of the hydrogenated product of the ring-opening polymer obtained in Production Example 1 were dried at 70 ° C for 2 hours using a hot air dryer in which air was passed to remove water. Next, the pellets were processed into a short-screw extruder having a coat hanger type T-die with a lip width of 1400 mm (manufactured by Mitsubishi Heavy Industries, Ltd .: screw diameter 90 mm, T-die lip member material is tungsten carbide, peel strength with molten resin 44).
N) was used for melt extrusion molding to produce a film having a thickness of 80 μm. The extrusion molding was performed in a clean room of class 10,000 or less under the molding conditions of a molten resin temperature of 240 ° C. and a T die temperature of 240 ° C. About the obtained film, the value of X is 2.3%, the value of Y is 2.1%, | XY
The value of | / {(X + Y) / 2} was 0.09. Re of film, variation of Re, stretching processability, R after stretching
The variation of e was evaluated by the above method. The results are shown in Table 1.
Described in.

[0024]

[Table 1]

[Examples 2 and 3] Example 1 except that the pellets obtained in Production Example 2 or Production Example 3 were used, respectively.
A film was produced in the same manner as in. X value, Y value and | X−Y | / {(X + Y) / for the obtained film
The values of 2} are listed in Table 1. The Re of the film, the variation of Re, the stretching processability, and the variation of Re after stretching were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 T-die lip material made of chrome-plated stainless steel (peel strength with molten resin 81
A film was produced in the same manner as in Example 1 except that N) was changed. Regarding the obtained film, the value of X, the value of Y and the value of | X−Y | / {(X + Y) / 2} are shown in Table 1. The Re of the film, the variation of Re, the stretching processability, and the variation of Re after stretching were evaluated in the same manner as in Example 1. The results are shown in Table 1.

A dial type thickness gauge was used for all the films obtained in the above Examples and Comparative Examples.
The thickness of the film was measured according to the physical property measurement method (6), and the ratio of the difference between the average value and each measured value to the average value (thickness variation) was calculated. It was ± 4% or less in some places.

From the evaluation results shown in Table 1, the value of X, the value of Y and the value of | X−Y | / {(X + Y) / 2} were obtained in Examples 1 to 3 within the scope of the present invention. The film has a small variation in Re and Re and is excellent in stretch processability. Also, the value of X, the value of Y and | X−Y | / {(X + Y) /
It can be seen that the smaller the value of 2}, the smaller the variation of Re and Re. On the other hand, the film obtained in Comparative Example 1 in which the value of X, the value of Y and the value of | X−Y | / {(X + Y) / 2} are not within the scope of the present invention is a dial type thickness gauge. Even if the measured variation in thickness is within ± 4%, the variation in Re and Re becomes large. Therefore, when used as a polarizing film protective film, light leakage occurs and it cannot be used in a wide band as a phase plate.

[0029]

According to the present invention, there is no light leakage when used as a protective film for a polarizing film, and even if it is stretched to a high magnification and used, the breaking strength is large, and as a quarter-wave phase plate. An optical film that can be used in a wide wavelength range and a method for manufacturing the same are provided.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08J 5/18 CER C08J 5/18 CER 4J100 CEZ CEZ G02B 1/04 G02B 1/04 G02F 1/13363 G02F 1 / 13363 // G02F 1/1335 510 1/1335 510 B29K 45:00 B29K 45:00 B29L 7:00 B29L 7:00 C08L 45:00 C08L 45:00 65:00 65:00 F term (reference) 2H049 BA02 BA07 BA42 BB18 BB22 BB42 BC09 BC22 2H091 FA08 FA11 FC08 FC16 FC21 FC29 FC30 FD07 FD10 FD14 GA01 GA17 LA03 LA11 LA12 LA13 LA16 4F071 AA39 AA69 AF30 AH19 BA01 BB06 CA32 K03 CA32 K03K03K15K34 A1573A15K34 A1573A11 AH73 AP11 AR12 AR12 CC02 CE03 CF01 CG08 4J100 AR03Q AR05Q AR11P AR16Q AR18Q AR21P AR22P BA03P CA04 DA01 DA04 DA62 FA03 JA32

Claims (5)

[Claims] 1. A repeating unit having a bicyclo [3.3.0] octane structure is contained in an amount of 55 to 90% by weight, a weight average molecular weight is 25,000 to 50,000, and a molecular weight distribution is 1.2 to 3. A film obtained by melt-extruding an alicyclic structure-containing polymer having a size of 0.5, the film having an area of 1 m ² at an interval of 5 cm in the flow direction at the time of molding and 20 cm in the direction orthogonal to the flow. 10 selected at intervals
For measurement of thickness at 0 places, when the arithmetic average value as a A _X, to Xmax the largest of the absolute value of the difference between the measured values and the average value A _X, for the A _X of Xmax The ratio X (%), at intervals of 5 cm in the direction orthogonal to the flow at the time of molding, and at intervals of 20 cm in the flow direction,
When the arithmetic mean value of the thickness measurement values at 100 selected locations is A _Y and the maximum absolute value of the difference between the average value A _Y and the measurement value is _Y max, the A of _Y max ratio _Y Y a (%), but the optical film characterized by satisfying the following relationship. (1) X ≦ 5 and Y ≦ 5, or (2) X ≦ 8 and Y ≦ 8 and | X−Y | / {(X +
Y) / 2} ≦ 0.35 2. The optical film according to claim 1, which is a protective film for a polarizing film. 3. An optical film obtained by further stretching the optical film according to claim 1. 4. The optical film according to claim 3, which is a phase plate. 5. A repeating unit having a bicyclo [3.3.0] octane structure is contained in an amount of 55 to 90% by weight, a weight average molecular weight is 25,000 to 50,000, and a molecular weight distribution is 1.2 to 3. The alicyclic structure-containing polymer of No. 5 is melted, and the melt polymer is extruded into a film from a die having a lip portion having a peel strength of 75 N or less with the melt polymer, and the area of the film is 1 m ² In the range of 5 cm in the flow direction at the time of molding, and 20 cm in the direction orthogonal to the flow at intervals of 100 cm, the arithmetic average value of the measured thickness values at 100 selected points is defined as A _X, and this average value A _X And Xmax is the maximum absolute value of the difference between the measured value and the measured value, the ratio X (%) of Xmax to the A _X ,
The arithmetic mean value of the measured values of thickness at 100 selected points at an interval of 5 cm in the direction orthogonal to the flow at the time of molding and at an interval of 20 cm in the direction of flow was defined as A _Y , and the average value A _Y and the measured value The method of producing an optical film is characterized in that when the maximum absolute value of the difference between Ymax and Ymax is Ymax, the ratio Y (%) of Ymax to _AY satisfies the following relationship. (1) X ≦ 5 and Y ≦ 5, or (2) X ≦ 8 and Y ≦ 8 and | X−Y | / {(X +
Y) / 2} ≦ 0.35