JP4577369B2 - Stretched film - Google Patents

Description

  The present invention relates to a stretched film, and more particularly relates to a stretched film having excellent accuracy without wrinkles and thickness unevenness, and having no dimensional change over a long period of time and excellent stability of optical properties.

  A liquid crystal display (LCD) has features such as high image quality, thinness, light weight, and low power consumption, and is widely used as a flat panel display for televisions, personal computers, and the like. In addition, a super-twisted nematic (STN) liquid crystal with a simple matrix system and a simple structure is used for the color liquid crystal display, but the problem is that the hue of the liquid crystal display is green or yellow-red due to the elliptically polarized light based on the STN liquid crystal. Produce. As one of the means for solving this problem, a countermeasure is used in which a retardation film is used, the retardation is compensated by birefringence of the STN liquid crystal, and the elliptically polarized light is returned to linearly polarized light.

  As a method for producing this retardation film, for example, from a film uniaxially stretched in the length direction or width direction of an unstretched film, a predetermined inclination angle with respect to the side of the stretched film so as to have a desired orientation axis Thus, a method of cutting the stretched film is known. However, this method has a problem that even if the cutting is performed so as to obtain the maximum area, a cutting loss always occurs and the product yield is poor.

  Patent Document 1 discloses that a plastic film such as polycarbonate or polyester is stretched uniaxially in the transverse or longitudinal direction, and the stretching direction is different from the stretching direction at different speeds on the left and right sides of the stretching direction. Thus, it has been proposed to incline the orientation axis with respect to the uniaxial stretching direction. According to this method, the inclination angle of the orientation axis can be easily changed by controlling the stretching ratio in the longitudinal and transverse directions, and an obliquely oriented film in which the orientation axis is inclined at various angles with respect to the end side can be obtained efficiently. be able to. However, the stretched film obtained by this method has wrinkles or uneven thickness, and it has been difficult to obtain a film with excellent accuracy.

Furthermore, Patent Document 2 discloses a holding means locus L1 from a substantial holding start point at one end of a polymer film such as polyvinyl alcohol to a substantial holding release point, and a substantial other end of the polymer film. The trajectory L2 of the holding means from the holding start point to the substantial holding release point and the distance W to the two substantial holding release points satisfy the relationship of Expression (1): | L2-L1 |> 0.4W. It describes a method for producing an optical polymer film that satisfies the requirements, maintains the support of the polymer film, stretches in a state where the volatile content is 5% or more, and then reduces the volatile content while shrinking.
However, the film obtained by this method also has a problem that optical characteristics change when used for a long period of time.
Japanese Patent Laid-Open No. 2000-9912 JP 2002-86554 A

  The present invention has been made in view of the above-mentioned problems of the prior art, and is excellent in accuracy without wrinkles and thickness irregularities, and has no long-term dimensional change and excellent optical property stability. It is an object of the present invention to provide a stretched film useful as the above.

  As a result of intensive studies to solve the above-mentioned object, the present inventors have found that in order to obtain a stretched film having excellent accuracy without wrinkles and thickness unevenness, and having no dimensional change over the long term, and having stable optical properties, It is preferable to use an unstretched film made of a cyclic structure-containing polymer resin, and the unstretched film is made of an alicyclic structure-containing polymer resin having a volatile component content of a predetermined concentration or less. The inventors have found that it is preferable to obliquely stretch at a predetermined angle with respect to the width direction, and have completed the present invention.

Thus, according to the present invention, the volatile component content is 100 ppm or less, the weight average molecular weight is 10,000 to 50,000, the molecular weight distribution is 1.2 to 3.5, and tetracyclododecene. Or a born product of a norbornene polymer obtained by ring-opening polymerization of methanotetrahydrofluorene or a derivative thereof and then hydrogenating the derivative, dicyclopentadiene or a derivative thereof, and unstretched obtained by melt extrusion molding A long stretched film obtained by continuously stretching the film obliquely in a direction of 1 to 50 degrees with respect to its width direction is provided.

  The stretched film of the present invention has no wrinkles or thickness unevenness, is excellent in accuracy, has no dimensional change in the long term, and is excellent in stability of optical characteristics, and is useful as a retardation film. Moreover, since the stretched film of this invention is elongate, it can be wound up and preserve | saved at roll shape. For example, when the stretched film of the present invention is used as a retardation plate and bonded to a long quarter-wave plate to produce an (elliptical) circularly polarizing plate, continuous production becomes possible, so high productivity. There is an advantage that can be obtained. Furthermore, since the stretched film of the present invention is stretched at a predetermined angle, there is no need to cut it obliquely so as to be at the predetermined angle, and continuous processing such as roll-to-roll is possible.

Hereinafter, the present invention will be described in detail.
1) Unstretched film
The unstretched film used in the present invention is a hydrogen of a norbornene polymer obtained by ring-opening polymerization of tetracyclododecene or a derivative thereof, dicyclopentadiene or a derivative thereof, and methanotetrahydrofluorene or a derivative thereof, followed by hydrogenation. Consists of chemicals.

  Tetracyclododecene or its derivatives include tetracyclo [4.4.0.1. ^2,5 . 1 ^{7, 10} ] Dodec-3-ene (common name: tetracyclododecene) and derivatives of this compound (having a substituent in the ring). As dicyclopentadiene or a derivative thereof, tricyclo [4.3.0.1 ^2,5 ] Deca-3,8-diene (common name: dicyclopentadiene) and derivatives of this compound (having a substituent in the ring). As methanotetrahydrofluorene or a derivative thereof, 7,8-benzotricyclo [4.3.0.1] is used. ^2,5 ] Dec-3-ene (common name: methanotetrahydrofluorene) and derivatives of this compound (having a substituent in the ring).

  As the ring-opening polymerization catalyst to be used, for example, a catalyst comprising a metal halide such as ruthenium or osmium and a sulfate or acetylacetone compound and a reducing agent; or a metal halide such as titanium, zirconium, tungsten or molybdenum Or a catalyst comprising an acetylacetone compound and an organoaluminum compound;

The molecular weight of the norbornene-based polymer obtained by ring-opening polymerization of tetracyclododecene or a derivative thereof, dicyclopentadiene or a derivative thereof, and methanotetrahydrofluorene or a derivative thereof is appropriately selected according to the purpose of use. Polyisoprene or polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography using cyclohexane (toluene if the polymer resin does not dissolve) as a solvent, usually 10,000 to 100,000, Preferably it is 25,000-80,000, More preferably, it is 25,000-50,000. When the weight average molecular weight is in such a range, the mechanical strength and moldability of the film are highly balanced and suitable.

A hydride of a norbornene polymer obtained by ring-opening polymerization of tetracyclododecene or a derivative thereof, dicyclopentadiene or a derivative thereof, and methanotetrahydrofluorene or a derivative thereof is added to a solution of the norbornene polymer, nickel, It can be obtained by adding a known hydrogenation catalyst containing a transition metal such as palladium and hydrogenating a carbon-carbon unsaturated bond, preferably 90% or more.

The glass transition temperature of the hydride of norbornene-based polymer used in the present invention may be appropriately selected according to the purpose of use, but is preferably 80 ° C. or higher, more preferably in the range of 100 to 250 ° C. A film containing an alicyclic structure-containing polymer resin having a glass transition temperature in such a range is excellent in durability without causing deformation or stress in use at high temperatures.

The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the hydride of norbornene-based polymer used in the present invention is not particularly limited, but is usually 1.0 to 10.0, preferably 1.0 to 4.0, more preferably in the range of 1.2 to 3.5.

In the present invention, among hydrides of norbornene-based polymers, a resin containing 10% by weight or more of a repeating unit having a tricyclo [4.3.0.1 ^2,5 ] decane-7,9-diyl-ethylene structure. Furthermore, in addition to this, a resin containing 55 to 90% by weight of a repeating unit having a bicyclo [3.3.0] octane-2,4-diyl-ethylene structure is more preferable. By using such a resin, it is possible to obtain a stretched film having no dimensional change over a long period of time and excellent optical property stability.

As a method for setting the repeating unit having a tricyclo [4.3.0.1 ^2,5 ] decane-7,9-diyl-ethylene structure in the hydride of norbornene-based polymer to the above range, for example, tetracyclo [4 .4.0.1 ^2,5 . 1 ^{7, 10} ] Dodeca-3-ene (also known as tetracyclododecene), or a monomer mixture containing 10% by weight or more thereof (having a substituent in the ring), a known metathesis ring-opening polymerization method And a method of hydrogenating a ring carbon-carbon unsaturated bond by a known method after polymerization.

Examples of the method for setting the repeating unit having a bicyclo [3.3.0] octane-2,4-diyl-ethylene structure in the above range include, for example, a norbornene monomer having a structure in which a five-membered ring is bonded to a norbornene ring A method of polymerizing a monomer mixture containing 55 to 90% by weight by a known metathesis ring-opening polymerization method and then hydrogenating a ring carbon-carbon unsaturated bond by a known method. Examples of norbornene monomers having a structure in which a five-membered ring is bonded to a norbornene ring include tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene and derivatives thereof (having a substituent in the ring). ), 7,8-benzotricyclo [4.3.0.1 ^0,5 ] dec-3-ene and derivatives thereof.

In the present invention, a norbornene monomer having a structure in which a five-membered ring structure is bonded to the norbornene ring and / or tetracyclo [4.4.0.1 ^2,5 . Polymers obtained by ring-opening copolymerization of ^{17, 10} ] dodec-3-ene or their derivatives with other monomers copolymerizable therewith can also be preferably used.

Among these, the hydride of the norbornene-based polymer contains 10% by weight or more of a repeating unit having a tricyclo [4.3.0.1 ^2,5 ] decane-7,9-diyl-ethylene structure, A resin having a weight average molecular weight of 25,000 to 80,000 and a molecular weight distribution of 1.1 to 4.0 is preferable. In addition, bicyclo [3.3.0] octane-2,4-diyl -It is particularly preferred to be a resin containing 55 to 90% by weight of repeating units having an ethylene structure, a weight average molecular weight of 25,000 to 50,000, and a molecular weight distribution of 1.2 to 3.5. By using such an alicyclic structure-containing polymer resin, a stretched film having no dimensional change in the long term, excellent optical properties, and excellent mechanical strength even when obliquely stretched is obtained. be able to.

The unstretched film can be obtained by forming a hydride of the norbornene polymer into a film shape. In this case, other additives and other thermoplastic resins can be added as long as the object of the present invention is not impaired.

  Examples of other additives include plasticizers and deterioration inhibitors. The plasticizer is added to improve the mechanical properties of the film or to increase the drying speed. Examples of the plasticizer to be used include phosphoric acid esters and carboxylic acid esters.

  Examples of phosphate esters include triphenyl phosphate and tricresyl phosphate. Examples of the carboxylic acid ester include phthalic acid esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, and diphenyl phthalate; citrate esters such as triethyl O-acetylcitrate and tributyl O-acetylcitrate; butyl oleate Higher fatty acid esters such as methylacetyl ricinoleate and dibutyl sebacate; trimetic acid esters; and the like.

  Examples of the deterioration preventing agent include an antioxidant, a peroxide decomposing agent, a radical inhibitor, a metal deactivator, an acid scavenger, and amines. The deterioration preventing agents are described in JP-A-3-199201, JP-A-5-1907073, JP-A-5-194789, JP-A-5-271471, JP-A-6-107854, and the like. .

  The addition amount of these other additives and other thermoplastic resins is usually 0 to 20% by weight, preferably 0 to 10% by weight, more preferably 0 to 5% with respect to the alicyclic structure-containing polymer resin. % By weight.

The method for molding the hydride of norbornene-based polymer into a film is not particularly limited, and a known molding method can be employed. For example, either a hot melt molding method or a solution casting method can be employed, but from the viewpoint of reducing volatile components in the sheet, it is preferable to use the hot melt molding method.

  The hot melt molding method can be further classified into a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, a stretch molding method, and the like. Among these, it is preferable to use a melt extrusion method in order to obtain a stretched film having excellent mechanical strength and surface accuracy.

  The molding conditions are appropriately selected depending on the purpose of use and the molding method. In the case of the melt extrusion molding method, the cylinder temperature is preferably set in the range of preferably 100 to 600 ° C, more preferably 150 to 350 ° C.

  The thickness of the unstretched film can be appropriately determined according to the purpose of use of the stretched film obtained. The thickness of the film is preferably 10 to 300 μm, more preferably 30 to 200 μm, from the viewpoint of obtaining a uniform stretched film by a stable stretching process.

2) Long stretched film The unstretched film obtained as described above is continuously stretched obliquely in the direction of an arbitrary angle θ (1 degree <θ <50 degrees) with respect to its width direction. It is possible to obtain a long stretched film having an orientation axis at an angle θ with respect to the width direction.

  By setting the angle θ to an arbitrary value between 1 and 50 degrees, the refractive index nx in the in-plane slow axis direction, the refractive index ny in the direction perpendicular to the in-plane slow axis, and the thickness direction The refractive index nz can be set to a desired value.

  The method of obliquely stretching is not particularly limited as long as it is continuously stretched in the direction of 1 to 50 degrees with respect to the width direction, and the orientation axis of the polymer is inclined to a desired angle. Can be adopted.

  Further, the stretching machine used for the oblique stretching is not particularly limited, and a conventionally known tenter type stretching machine that can add feeding force, pulling force, or take-up force at different speeds in the horizontal or longitudinal direction can be used. it can. In addition, the tenter type stretching machine includes a horizontal uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, but is not particularly limited as long as a long film can be continuously obliquely stretched. These types of stretching machines can be used.

  An example of oblique tenter stretching that can be used in the present invention is shown in FIG. As shown in FIG. 1, the unstretched film (11) obtained above is obliquely stretched using a tenter (31) while being conveyed in a certain direction (21). The film chucked at a certain position (41, 42) in FIG. 1 moves diagonally by moving the left side to the position (51L) at a slow speed (52L) and the right side to the position (51R) at a high speed (52R). Stretching is performed. FIG. 1 shows an example in which the film is obliquely stretched at an angle θ (1 <θ <50) with respect to the width direction B, and the orientation axis is the direction of A.

  The oblique stretching method that can be used in the present invention is not limited to that shown in FIG. For example, JP-A-50-83482, JP-A-2-113920, JP-A-3-182701, JP-A-2000-9912, JP-A-2002-86554, JP-A-2002-22944 Etc. can be used.

  The temperature at which the unstretched film is obliquely stretched is preferably between Tg-30 ° C and Tg + 60 ° C, more preferably from Tg-10 ° C, where Tg is the glass transition temperature of the alicyclic structure-containing polymer resin. The temperature range is Tg + 50 ° C. Moreover, a draw ratio is 1.01-30 times normally, Preferably it is 1.01-10 times, More preferably, it is 1.01-5 times.

  The stretched film of the present invention is substantially composed of a hydride of a norbornene polymer and has a volatile component content of 100 ppm or less. A stretched film having a volatile component content in the above range is excellent in the stability of optical characteristics in which display unevenness does not occur even when used for a long time.

  The volatile component is a relatively low boiling point substance having a molecular weight of 200 or less contained in a small amount in the alicyclic structure-containing polymer resin, and examples thereof include residual monomers and solvents. The content of the volatile component is the total of substances having a molecular weight of 200 or less contained in a small amount in the alicyclic structure-containing polymer resin, and is quantified by analyzing the alicyclic structure-containing polymer resin by gas chromatography. Can do.

  Examples of a method for obtaining a stretched film having a volatile component content of 100 ppm or less include, for example, (a) a method of obliquely stretching an unstretched film having a volatile component content of 100 ppm or less, and (b) a volatile component content of 100 ppm. Examples include a method of reducing the content of volatile components by using an unstretched film that exceeds 10% and drying during or after oblique stretching. Among these, the method (a) is preferable in order to obtain a stretched film in which the volatile component content is further reduced. In the method (a), in order to obtain an unstretched film having a volatile component content of 100 ppm or less, it is preferable to melt-extrude a resin having a volatile component content of 100 ppm or less.

  The saturated water absorption rate of the stretched film of the present invention is not particularly limited, but is preferably 0.01% or less, more preferably 0.007% or less. If the saturated water absorption exceeds 0.01%, a dimensional change may occur in the stretched film depending on the use environment, and internal stress may occur. For example, when used in a reflective liquid crystal display device, there is a possibility that display unevenness such as a partial blackening of the black display (appears whitish) may occur. A stretched film having a saturated water absorption rate in the above range is excellent in stability of optical properties in which display unevenness does not occur even when used for a long time.

  The stretched film of the present invention obtained as described above has an orientation axis of 1 to 50 degrees with respect to the width direction. Further, since there is no wrinkle or thickness unevenness, no dimensional change over a long period of time, and excellent optical properties, it is useful as a polarizing film or a retardation film.

  Hereinafter, the present invention will be described in more detail with reference to production examples, examples and comparative examples. [Part] and [%] in these examples are based on weight unless otherwise specified. However, the present invention is not limited to the following production examples and examples.

Various physical properties were measured according to the following methods.
(1) Molecular weight It measured by gel permeation chromatography (GPC) using cyclohexane as a solvent, and calculated | required the weight average molecular weight (Mw) of standard polystyrene conversion.
(2) Molecular weight distribution Measured by GPC using cyclohexane as a solvent, the weight average molecular weight (Mw) and the number average molecular weight (Mn) in terms of standard polystyrene are obtained, and the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) (Mw / Mn) was calculated.
(3) Glass transition temperature (Tg)
The glass transition temperature (Tg) was measured by DSC based on JIS K7121.

(4) Hydrogenation rate The hydrogenation rate (%) of the main chain and aromatic ring of the polymer was calculated by measuring ¹ H-NMR.
(5) Measurement of volatile component content The volatile component content of the film was quantified as a total of components having a molecular weight of 200 or less by gas chromatography.
(6) Film thickness of film It measured using the offline thickness measuring apparatus (model: TOF-4R, Yamabun Electric Co., Ltd. product).

(7) Measurement of saturated water absorption The saturated water absorption of the stretched film was measured according to JIS K7209.
(8) Dimensional stability test of stretched film The prepared stretched film was treated under the following two conditions, and then the dimensional change rate in the orientation axis direction was measured. The case where the dimensional change rate was within ± 0.05% was evaluated as “good”, and the case where it exceeded ± 0.05% was evaluated as “bad”. As for the sign, the contraction direction was “−” and the extension direction was “+”.
Condition A: Leave for 30 days in an environment of temperature 30 ° C. and humidity 40% Condition B: Leave in an environment of temperature 30 ° C. and humidity 80% for 30 days

(8) Optical property test of stretched film The variation of the orientation angle with respect to the width direction of the stretched film produced is ± 0.5 degrees with respect to the average value over the entire width direction (excluding the range of 50 mm width of the tenter chuck portion). The following cases were evaluated as “good” and cases exceeding ± 0.5 degrees were evaluated as “bad”.

(Production Example 1)
In a nitrogen atmosphere, 500 parts of dehydrated cyclohexane, 0.82 part of 1-hexene, 0.15 part of dibutyl ether and 0.30 part of triisobutylaluminum were mixed in a reactor at room temperature, and then kept at 45 ° C. 80 parts of tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene (dicyclopentadiene, hereinafter abbreviated as “DCP”), 7,8-benzotricyclo [4.3.0 .1 ^2,5] dec-3-ene (hereinafter abbreviated as "MTF".) 70 parts, and tetracyclo [4.4.0.1 ^2,5. 1 ^7,10 ] dodec-3-ene (hereinafter abbreviated as “TCD”) and a norbornene-based monomer mixture and 40 parts of tungsten hexachloride (0.7% toluene solution) over 2 hours. Added continuously and polymerized. To the polymerization solution, 1.06 part of butyl glycidyl ether and 0.52 part of isopropyl alcohol were added to inactivate the polymerization catalyst, and the polymerization reaction was stopped.

  Next, 270 parts of cyclohexane are added to 100 parts of the reaction solution containing the obtained ring-opening polymer, and 5 parts of a nickel-alumina catalyst (manufactured by JGC Chemical Co., Ltd.) is added as a hydrogenation catalyst. The mixture was pressurized to 5 MPa and heated to 200 ° C. with stirring, and then reacted for 4 hours to obtain a reaction solution containing 20% of a DCP / MTF / TCD ring-opening copolymer hydride polymer. After removing the hydrogenation catalyst by filtration, an antioxidant (trade name: Irganox 1010, manufactured by Ciba Specialty Chemicals) was added to the resulting solution and dissolved (the amount of the antioxidant added) 0.1 parts per 100 parts polymer).

  Then, using a cylindrical concentrating dryer (manufactured by Hitachi, Ltd.), the cyclohexane and other volatile components, which are solvents, are removed from the solution at a temperature of 270 ° C. and a pressure of 1 kPa or less. A combined hydride (hydrogenated polymer) was obtained.

  When the copolymerization ratio of each norbornene monomer in the obtained hydrogenated polymer was calculated from the composition of residual norbornenes in the solution after polymerization (by gas chromatography method), DCP / MTF / TCD = 440 It was almost equal to the charged composition at / 25/35. This hydride had a weight average molecular weight (Mw) of 35,000, a molecular weight distribution of 2.1, a hydrogenation rate of 99.9%, and a Tg of 134 ° C.

  Next, the ring-opened polymer hydride obtained above was extruded using a T-die type film extruder having a resin melt extruder equipped with a 65 mmφ screw, and a film having a width of 500 mm and a thickness of 100 μm was extruded. The unstretched film A was obtained by molding. The volatile component content of the obtained unstretched film A was 100 ppm or less, and the thickness unevenness was 3.2 μm.

(Production Example 2)
170 parts of DCP and 8-ethyl-tetracyclo [4.4.0.1 ^2,5 . Polymerization and hydrogenation reaction in the same manner as in Production Example 1 except that a norbornene-based monomer mixture composed of 30 parts of 17, ¹⁰ ] dodec-3-ene (hereinafter abbreviated as “ETD”) was used. To obtain a hydrogenated ring-opened polymer. The hydride of this ring-opened polymer had a weight average molecular weight (Mw) of 35,000, a hydrogenation rate of 99.9%, a molecular weight distribution of 2.0, and a Tg of 105 ° C. The cyclic polymer hydride was extruded in the same manner as in Production Example 1 to obtain an unstretched film B having a width of 500 mm and a thickness of 100 μm. The volatile component content of the obtained unstretched film B was 100 ppm or less, and the thickness unevenness was 3.5 μm.

(Example 1) Production of stretched film A The unstretched film A obtained in Production Example 1 was heated to 120 ° C and introduced into a tenter stretching machine according to Fig. 1, and the rate of movement was 5% to the left and right moving speed. A stretched film A was obtained by giving a difference and carrying out a tensile stretching in the machine direction due to a speed difference as well as a transverse uniaxial stretching (width direction). The angle of the orientation axis with respect to the width direction of the stretched film was 19.5 degrees on average.

(Example 2) Production of stretched film B The unstretched film B obtained in Production Example 2 was heated to 95 ° C and introduced into a tenter stretching machine according to Fig. 1, and a speed difference of 10% was applied to the lateral movement speed. A stretched film B was obtained by stretching in the longitudinal direction due to the speed difference as well as transverse uniaxial stretching (width direction). The orientation axis with respect to the width direction of the stretched film B was 45 degrees on average.

Comparative Example 1 Production of Stretched Film C A polycarbonate resin having a width of 500 mm and a thickness of 100 μm (thickness unevenness of 6.7 μm) was obtained by melt extrusion molding of a polycarbonate resin in the same manner as in Production Example 1. Next, this film was heated to 150 ° C. and introduced into a tenter stretching machine according to FIG. 1, and a lateral uniaxial stretching (width direction) was performed with a 5% speed difference between the left and right moving speeds, along with the longitudinal direction due to the speed difference. A stretched film C was obtained by performing tensile stretching in the direction. The orientation axis with respect to the width direction of the stretched film C was 18.9 degrees on average.

Comparative Example 2 Production of Stretched Film D Using a polycarbonate film (width 500 mm, thickness 100 μm, thickness unevenness 2.6 μm, volatile component content 30,000 ppm) obtained by a solution casting method as a methylene chloride solvent. Then, continuous oblique stretching was performed in the same manner as in Comparative Example 1, and after stretching, drying was continuously performed with hot air at 100 ° C. for 60 seconds. The stretched film obtained had a volatile component content of 5,000 ppm.

  Orientation axis angle with respect to width direction of stretched films A to D obtained in Examples and Comparative Examples, variation of orientation axis angle, presence or absence of wrinkles, thickness unevenness (difference between maximum thickness and minimum thickness), volatile component content Table 1 shows the evaluation of dimensional stability and stability of optical properties. In Table 1, the presence or absence of wrinkles was evaluated by visually observing the stretched film.

  From Table 1, stretched films A and B of Examples 1 and 2 are free from wrinkles, have no thickness unevenness as compared with stretched films C and D of Comparative Examples 1 and 2, and have a long-term dimensional stability and optical properties. Excellent stability of characteristics.

In an Example and a comparative example, it is plane explanatory drawing which carries out diagonal stretch of the unstretched film.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Unstretched film 21 ... Film conveyance direction 31 ... Tenter 41, 42 ... Chuck position 51R ... Film right movement position 51L ... Film left movement position 52R ... Right movement speed 52L ... Left movement speed A ... Orientation axis direction B ... Width direction

Claims (1)

The volatile component content is 100 ppm or less, the weight average molecular weight is 10,000 to 50,000, the molecular weight distribution is 1.2 to 3.5, tetracyclododecene or a derivative thereof, dicyclopentadiene Or a derivative thereof and a hydride of a norbornene polymer obtained by ring-opening polymerization of methanotetrahydrofluorene or a derivative thereof and then hydrogenating the unstretched film obtained by melt extrusion molding in the width direction. On the other hand, a long stretched film obtained by continuously obliquely stretching in the direction of 1 to 50 degrees.

Images