JP2014117938A - Film drawing method, method of producing oriented film and oriented film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film drawing method which enables reducing nonuniformity of molecular orientation axes with respect to positions in the film width direction and preventing occurrence of wrinkles, a method of producing an oriented film and an oriented film.SOLUTION: A method of drawing a belt-like film F comprises drawing the film F in such a way that the molecular orientation axes are inclined to the width direction of the film F, while moving the film F in the longitudinal direction, and comprises: a drawing step of drawing the film F while moving the film F in such a way that both end parts, in the width direction, of the film F move at different mobile speeds; and a tension adjustment step of moving, after the drawing step, a low-speed-side end part of the film F having a lower mobile speed toward a high-speed-side end part having a higher mobile speed in such a way that both the end parts, in the width direction, of the film F approach mutually, while moving the film F in such a way that both end parts, in the width direction, of the film F move at different mobile speeds, carried out in order. The configuration can reduce the tension near the low-speed-side end part, and application of a large tension to the side of the low-speed-side end part in the longitudinal direction is thus allowable, resulting in prevention of occurrence of wrinkles in the film F.

Description

  The present invention relates to a method for stretching a film, a method for producing a stretched film, and a stretched film. More specifically, a retardation film having a uniform molecular orientation axis is used for optical compensation such as prevention of coloring, expansion of viewing angle and prevention of reflection of external light in image display devices such as liquid crystal display devices and organic EL display devices. The present invention relates to a method for stretching a film for producing a film, a method for producing a stretched film employing the method for stretching such a film, and a stretched film produced by such a production method.

  Retardation films used for optical compensation such as prevention of coloring, widening of viewing angle, and prevention of reflection of external light in image display devices such as liquid crystal display devices and organic EL display devices are in a state in which the molecular orientation axes are aligned. It is formed as follows. This retardation film is usually used by being attached to a polarizing plate, and at this time, the molecular orientation axis is arranged at a desired angle with respect to the transmission axis of the polarizing plate. For this reason, it is necessary to manufacture the retardation film so that the molecular orientation axis is in a predetermined direction.

  When the retardation film as described above is used for a liquid crystal display device or the like together with a polarizing plate, since a general liquid crystal display device is a square shape, the polarizing plate and the retardation film are also formed in a square shape. As described above, in order to arrange the retardation film so that the molecular orientation axis is inclined at a desired angle with respect to the transmission axis of the polarizing plate, the molecular orientation axis of the retardation film is set to each side. May have to be manufactured in a tilted state.

  The retardation film is produced by cutting a band-shaped film, and the molecular orientation axis of the conventional band-shaped film is parallel to the width direction of the film or orthogonal to the width direction. For this reason, when a retardation film is formed by cutting a strip-shaped film so that the molecular orientation axis is inclined with respect to each side, each side of the retardation film is in the width direction of the strip-shaped film. The strip film must be cut so that it is tilted.

  However, when the retardation film is formed by cutting the belt-shaped film by the method as described above, a large amount of portions that cannot be used as the retardation film are formed at the edge of the belt-shaped film, and the production yield of the film is poor. The problem has arisen.

  As a method for preventing such a problem, a method of forming a retardation film using a band-shaped film in which molecular orientation axes are inclined with respect to the width direction is considered. When this method is adopted, if the molecular orientation axis of the belt-like film is inclined at a desired angle with respect to the width direction, the film can be used as a retardation film up to the end of the belt-like film, thereby improving the production yield. be able to. And since it becomes possible to bond with a polarizing plate (polarizer) as it is, without cutting a strip | belt-shaped film, the production rate which produces the polarizing plate which affixed the phase difference film can be improved.

  In order to realize the above-described method, a technique for producing a strip-like film in which the molecular orientation axis is inclined with respect to the width direction has been developed.

  For example, Patent Document 1 discloses a technique for producing a stretched film by holding both ends in the width direction of a strip-shaped plastic film by a tenter stretching machine and stretching the strip-shaped plastic film in the longitudinal direction while stretching the strip-shaped plastic film. Has been. And in the technique of patent document 1, the speed which pulls the both ends of the width direction of a plastic film to a longitudinal direction is made into the speed which is different in the both ends of the width direction.

  For this reason, in the technique of Patent Document 1, the stretching ratio in the longitudinal direction and the width direction can be controlled by adjusting the speed of pulling both ends of the belt-shaped plastic film in the longitudinal direction and the amount of stretching in the width direction. The inclination angle of the molecular orientation axis can be easily changed. That is, a strip-shaped stretched film in which the molecular orientation axis is inclined at a desired angle with respect to the width direction can be produced.

  However, in the technique of Patent Document 1, the amount of pulling the belt-shaped plastic film in the width direction is symmetric with respect to the center in the width direction, whereas the speed of pulling in the longitudinal direction is asymmetric with respect to the center in the width direction. It has become. For this reason, since the stress applied to the belt-shaped plastic film becomes asymmetric with respect to the center in the width direction, there arises a problem that the molecular orientation axis of the produced stretched film becomes uneven depending on the position in the width direction. ing. In this case, the quality of the retardation film produced from the stretched film is deteriorated, which may cause problems in the final product.

  In addition, while the tenter stretching machine holds both ends of the film, the film is in a state where tension is applied. For this reason, when the tenter stretching machine releases the end portion of the film, there is a possibility that wrinkles will be formed in the vicinity of the end portion on the slow pulling side due to the tension applied so far. The film on which such wrinkles are formed does not become a product and must be discarded, and wrinkles must be avoided.

A technique for preventing the generation of wrinkles as described above is disclosed in Patent Document 2.
In Patent Document 2, as in Patent Document 1, there is disclosed a technique in which both ends in the width direction of a belt-like film are held by a tenter stretching machine and the speed at which both ends in the width direction are pulled in the longitudinal direction is different. Yes.
And in patent document 2, since the edge part by which the conveyance speed is slow in the width direction of a film is extended | stretched by winding up the film extended | stretched at the speed | rate faster than the tenter chain of the high-speed side of a tenter drawing machine, it extended | stretched. It is described that the film can be wound up without wrinkling.

Japanese Patent Laid-Open No. 2000-9912 JP 2009-143208 A

  However, as in the technique of Patent Document 2, even when a film stretched at a higher speed than the tenter chain on the high speed side of the tenter stretching machine is wound, wrinkles are formed when the tenter stretching machine releases the end of the film. It is difficult to prevent completely.

  Further, even with the technique of Patent Document 2, it is difficult to eliminate the non-uniformity in the width direction of the molecular orientation axis caused by the asymmetry of stress applied to the belt-like film.

  In view of the above circumstances, the present invention provides a method for stretching a film, a method for producing a stretched film, and a stretched film that can reduce the non-uniformity of molecular orientation axes depending on the position in the film width direction and prevent the occurrence of wrinkles. For the purpose.

(Film stretching method)
The film stretching method of the first invention is a film stretching method for stretching the film so that the molecular orientation axis is inclined with respect to the width direction of the film while moving the belt-like film in the longitudinal direction, Stretching the film by moving both ends in the width direction at different moving speeds, and stretching the film after the stretching process, moving both ends in the width direction of the film at different moving speeds, A tension adjusting step of sequentially moving a low-speed side end portion having a low moving speed toward a high-speed side end portion having a high moving speed so that both end portions in the width direction of the film approach each other.
The film stretching method according to a second aspect of the present invention is the film stretching method according to the first aspect, wherein, in the tension adjustment step, the width of the film is 0 with respect to the maximum width of the film in the stretching step. It is made to approach until it decreases by 1 to 25%.
(Method for producing stretched film)
The method for producing a stretched film of the third invention is a method for producing a belt-like film having a molecular orientation axis inclined with respect to the width direction, and the belt-like film is stretched by the film stretching method of the first or second invention. It is characterized by doing.
(Stretched film)
The stretched film of the fourth invention is a strip-shaped stretched film produced by the method for producing a stretched film described in the third invention, wherein the variation in the inclination of the molecular orientation axis in the width direction is relative to a predetermined inclination. It is characterized by being within plus or minus 1 °.

According to the first invention, in the tension adjusting step, the low-speed side end is brought close to the high-speed side end while the film is moved at both ends in the width direction at different moving speeds. Can be reduced. Therefore, it is possible to apply a large tension in the longitudinal direction to the low speed side end side (that is, to make the winding speed on the low speed side end side equal to that of the high speed side), so that wrinkles are hardly generated.
According to the second invention, since the width of the film is narrowed within an appropriate range, variation in the inclination of the molecular orientation axis in the width direction of the film can be suppressed within an appropriate range.
(Method for producing stretched film)
According to the third invention, it is possible to form a stretched film having a small variation in the inclination of the molecular orientation axis in the width direction of the film and having few wrinkles. Then, most of the stretched film can be used as a retardation film, and defective products can be reduced when the retardation film is formed, so that the yield can be improved.
(Stretched film)
According to the 4th invention, the dispersion | variation in the inclination of a molecular orientation axis | shaft can be made small substantially in the whole stretched film. Therefore, almost the entire stretched film can be used as a retardation film, and defective products can be reduced when the retardation film is formed, so that the yield can be improved.

It is principal part schematic explanatory drawing of the state which has extended | stretched the film F with the extending | stretching method of the film of this embodiment. It is a schematic explanatory drawing of the stretched film manufacturing equipment EE which enforces the stretching method of the film of this embodiment. It is the graph which showed the experimental result.

  The film stretching method of the present invention is a method of stretching a film so that the molecular orientation axis of the band-shaped polymer film is inclined with respect to the width direction, and the molecular orientation axis in the width direction of the stretched film is It is characterized in that variation can be reduced.

  The polymer film stretched by the film stretching method of the present invention may be a thermoplastic resin film, and the material is not particularly limited. For example, polycarbonate, cyclic olefin resin, cellulose acetate, polyester, polysulfone, polyethersulfone, polystyrene, polyvinyl alcohol, polyvinyl chloride, polymethyl methacrylate, polyarylate, polyamide and the like can be mentioned.

  Moreover, the use of the stretched film manufactured by adopting the film stretching method of the present invention is not particularly limited. For example, it can be used as a retardation film used for optical compensation such as prevention of coloring, expansion of viewing angle and prevention of reflection of external light in an image display device such as a liquid crystal display device or an organic EL display device.

(Stretching machine)
Further, the stretching machine used in the film stretching method of the present invention can move both ends in the width direction of the belt-like film at different speeds along the longitudinal direction of the film, as will be described later. It is not particularly limited as long as both end portions in the width direction of the film can be approached and separated. For example, a uniaxial stretching machine such as a known tenter type stretching machine or a simultaneous biaxial stretching machine such as a pantograph type stretching machine or a linear motor type stretching machine can be used.
In the following, a case where stretching is performed using a tenter-type stretching machine will be described as a representative.

(Description of stretched film manufacturing equipment EE)
First, before explaining the film stretching method of the present embodiment, a facility for producing a stretched film by employing the film stretching method of the present invention will be briefly described with reference to FIG.

In FIG. 2, the code | symbol EE and the code | symbol F have each shown the film stretched | stretched by the stretched film manufacturing facility which manufactures a stretched film, and the stretched film manufacturing facility EE.
As shown in FIG. 2, the film F is drawn out from the raw roll BR, and then stretched to become a stretched film which is wound around the product roll MR.

As shown in FIG. 2, a heating device HD for heating the film F is provided between the raw roll BR and the product roll MR. The heating device HD has a structure that heats the film F while the film F passes through the space. That is, the heating device HD is provided in order to heat the film F passing through the space inside the heating device HD so that the film F is easily stretched.
The method for heating the film F in the heating device HD is not particularly limited, but generally, a method for heating the film F by blowing hot air onto the film F is employed.

In addition, a tenter type stretching machine including a plurality of gripping means Hh and Hs that hold both ends of the film F in the width direction is provided between the raw roll BR and the product roll MR.
As shown in FIG. 1, the tenter type stretching machine includes a pair of chains Ch and Cs that move a plurality of gripping means Hh and Hs from the raw roll BR toward the product roll MR (from left to right in FIG. 1). And a pair of guide rails Rh, Rs for guiding the movement of the plurality of gripping means Hh, Hs, and a control means for controlling the gripping release of the film F by the plurality of gripping means Hh, Hs.

More specifically, the chain Ch is disposed along the guide rail Rh. The plurality of gripping means Hh are attached side by side with the chain Ch, and are provided so as to move along the guide rail Rh. Each gripping means Hh holds the end portion in the width direction of the film F (the upper end portion in FIG. 1) at a predetermined position on the original roll BR side by the control means, and the predetermined holding side on the product roll MR side. It is controlled to release the end of the film F in the width direction at the position (release position HRP in FIG. 1).
On the other hand, the chain Cs is disposed along the guide rail Rs. The plurality of gripping means Hs are attached side by side with the chain Cs, and are provided so as to move along the guide rail Rs. Then, the plurality of gripping means Hs hold the end in the width direction of the film F (the lower end in FIG. 1) at a predetermined position on the original roll BR side by the control means, and on the product roll MR side. Control is performed to release the end of the film F in the width direction at a predetermined position (release position SRP in FIG. 1).

  In the tenter type stretching machine, the moving speed for moving the gripping means Hh (hereinafter referred to as moving speed Vh) is faster than the moving speed for moving the gripping means Hs (hereinafter referred to as moving speed Vs). It is controlled.

(Stretching method)
Next, a method for producing the stretched film of the present invention by stretching the film F by the stretching method of the present embodiment in the stretched film production facility EE described above will be described.
In the following, among the end portions in the width direction of the film F, the end portion held by the holding means Hh is referred to as a high speed side end portion, and the end portion held by the holding means Hs is referred to as a low speed side end portion. .

  In the stretched film manufacturing facility EE, when the film F is unwound from the raw roll BR, both ends in the width direction of the unrolled film F are sequentially held by a plurality of holding means Hh and Hs. As the plurality of gripping means Hh and Hs move, the film F moves toward the product roll MR and enters the heating device HD.

  When entering the heating device HD, the film F is heated by being blown with hot air, so the film F becomes soft and easily stretched.

(Extension section P1)
As described above, the gripping means Hh and Hs have different movement speeds, and the movement speed Vh of the gripping means Hh is faster than the movement speed Vs of the gripping means Hs. Therefore, in the first section (stretching section P1) in the heating device HD, the film F is stretched in the direction of the arrow in the figure due to the difference in moving speed between the high speed side end and the low speed side end. The In other words, the film F is stretched so that the molecular orientation axis is directed in the direction of the arrow.

It should be noted that in the stretching section P1, it is only necessary to stretch in an oblique direction using the difference between the moving speed Vh of the gripping means Hh and the moving speed Vs of the gripping means Hs. The arrangement of the guide rails Rh and Rs is not particularly limited and may be appropriately designed.
For example, as described in JP-A-2003-311823, JP-A-2009-143208, and JP-A-2012-163931, a pair of guide rails Rh and Rs may be provided substantially in parallel. As described above, the pair of guide rails Rh and Rs may be disposed so that the width of the film F is widened for each section, and the film F may be stretched in an oblique direction due to the speed difference of the gripping means and the widening of the film. Further, as described in Japanese Patent Application Laid-Open No. 2011-11434, guide rails Rh and Rs are arranged so that the path for transporting the film F is bent in a U-shape, and the film F is stretched in the width direction and / or the longitudinal direction. It may be to do.

  Said extending | stretching area P1 is corresponded to the extending | stretching process said to a claim.

(Tension adjustment section P2)
The film F that has passed through the stretching section P1 moves to the tension adjustment section P2. In the tension adjustment section P2, the guide rail Rs that guides the low speed side end is provided so as to gradually approach the guide rail Rh that guides the high speed side end. That is, the guide rail Rs located in the tension adjustment section P2 is provided so as to be inclined toward the guide rail Rh with respect to the axial direction of the guide rail Rs in the extending section P1. For this reason, the film F transported along the guide rails Rh and Rs is transported so that the low-speed side end of the film F approaches the high-speed side end toward the product roll MR.
Then, the width of the film F at the end of the tension adjustment section P2 is narrower than the width of the film F at the start of the tension adjustment section P2, that is, the width of the film F in the stretching section P1, so The tension in the width direction can be weakened. In other words, by adjusting the width of the film F at the end of the tension adjustment section P2, the tension in the width direction applied to the film F in the tension adjustment section P2 or the film F at the end of the tension adjustment section P2 is applied. The tension in the width direction can be adjusted.

  The tension adjustment section P2 corresponds to a tension adjustment step in the claims.

(Release section P3)
The film F that has passed through the tension adjustment section P2 moves to the release section P3 (section in which the film F is released from the gripping means Hh and Hs), and the gripping means Hh and Hs release both ends of the film F.

  Note that the release positions HRP and SRP at which the gripping means Hh and Hs release the film F in the release section P3 are not particularly limited. For example, the release positions HRP and SRP may be substantially the same position in the longitudinal direction of the film. Further, the release position HRP may be on the product roll side with respect to the release position SRP, and conversely, the release position SRP may be on the product roll side with respect to the release position HRP. Among these, from the relationship of the tension applied to the film F, it is most preferable that the gripping means Hs first releases the low speed side end of the film F, and then the gripping means Hh releases the high speed side end.

  Then, the film F released from the gripping means Hh and Hs, that is, the film F released from the tenter type stretching machine is wound up as a product roll MR.

  If the film F is stretched by the procedure as described above, an appropriate tension (that is, a desired tension) can be generated between both ends in the width direction of the film F in the tension adjustment section P2. Then, the inclination of the molecular orientation axis in the width direction of the film and the dispersion of the phase difference can be reduced, and when the gripping means Hs releases the film F, wrinkles can be suppressed from occurring at the low speed side end. That is, it is possible to produce a stretched film that is small in molecular orientation axis inclination (orientation angle) and retardation variation in the width direction of the film and that is free from wrinkles. For example, the variation in the inclination (orientation angle) of the molecular orientation axis with respect to the set inclination (angle) can be within ± 1 °.

  As described above, if the film F is stretched by the stretching method of the present embodiment, the wrinkles of the film F can be prevented and the nonuniformity of the molecular orientation axis of the film F can be reduced. The reason is presumed as follows.

  First, in the conventionally employed stretching method, when the film F is stretched for a predetermined period (that is, when the stretching process is completed), the film F is released in the state of the film width. For this reason, when the moving speed of the both ends of the film F differs, it is necessary to match the winding speed of the film F with the moving speed of the high speed side end. Then, since the film F near the low speed side end is pulled by winding on the product roll MR, wrinkles occur in the film F near the position where the gripping means releases the low speed side end (that is, in the vicinity of the release position SRP). .

On the other hand, when the film F is released after the tension adjustment in the tension adjustment section P2 as described above, wrinkle generation of the film F near the release position SPR at the low speed side end is suppressed. Became possible.
This is presumably because the tension applied to the film F due to the winding on the product roll MR could be reduced in the tension adjusting step.

In addition, the film F obtained by a conventionally employed stretching method has a high orientation angle and retardation value near the low-speed side end of the film F, and the uniformity of the orientation angle in the width direction of the film F, etc. There is a problem.
On the other hand, when the film F is released after the tension adjustment in the tension adjustment section P2 as described above, it is possible to obtain a film with little variation in the orientation angle and retardation value in the width direction. It has become possible.
This is because the tension applied to the film F due to the difference in the moving speeds at both ends of the film F can be relaxed in the tension adjusting process P2 because the tension is relaxed in the tension adjusting process P2. It is presumed that the variation in the orientation angle and the phase difference value that were generated by extending the low-speed side end of the film could be prevented.

(Rewinding speed of product roll MR)
The winding speed of the product roll MR is not particularly limited, but the peripheral speed of the product roll MR is equal to or higher than the moving speed Vh of the high speed side end or the moving speed Vh of the high speed side end. preferable. If the winding speed is such a speed, it is preferable that after the film F is released in the release section P3, the film F can be wound without being loosened.

  A mechanism for preventing the film F from slacking may be provided between the product roll MR and the release section P3. For example, if a nip roll or the like that sandwiches a film with a pair of rolls is provided between the product roll MR and the release section P3, the film F between the release section P3 and the nip roll etc. regardless of the winding speed of the product roll MR. A predetermined tension can be applied to the.

(Regarding the feed speed of the raw roll BR)
Further, the feed speed of the raw roll BR is not particularly limited, but is preferably the same speed as the moving speed Vs of the low speed side end.

(Regarding tension adjustment section P2)
The width of the film F at the end of the tension adjustment section P2 (that is, the width of the film F at the start of the release section P3) and the maximum width of the film F in the stretching process (that is, the width of the film F in the stretching section P1). The relationship is not particularly limited and may be set as appropriate. For example, the difference between the maximum width of the film F in the stretching section P1 and the width of the film F at the end of the tension adjusting section P2 may be 0.1 to 25% of the maximum width of the film F in the stretching section P1. However, 1 to 20% is preferable, 2 to 20% is more preferable, and 3 to 15% is particularly preferable.
The difference between the maximum width of the film F in the stretching section P1 and the width of the film F at the end of the tension adjusting section P2 can be appropriately set depending on the width of the film F in the stretching section P1 and the conveyance speed of the film F. For example, when the width of the film F in the stretching section P1 is wide or the transport speed of the film F is slow, the difference between the maximum width of the film F in the stretching section P1 and the width of the film F at the end of the tension adjustment section P2 Even if the ratio is 0.1% or more, the effect of preventing variation in the orientation angle and retardation value is obtained.

  And the inclination of the guide rail Rs of the tension adjustment section P2 with respect to the axial direction of the guide rail Rs of the extending section P1, that is, the rate of reducing the width of the film F is not particularly limited. What is necessary is just to design suitably so that characteristics, such as the inclination (orientation angle) of the molecular orientation axis | shaft of the stretched film manufactured, may become uniform in the width direction of a film.

  When the film was stretched by the film stretching method of the present invention, the variation in the optical characteristics in the width direction of the film and the occurrence of wrinkles were confirmed.

In the experiment, a film made of an olefin resin having a width of 500 mm fed from an origin roll was stretched by a tenter stretching machine to form a stretched film, and the formed stretched film was wound to form a product roll.
Then, about the stretched film wound up by the product roll, the change by the position of the orientation angle (inclination of the molecular orientation axis with respect to the width direction) in the width direction and the change by the position of the retardation value in the width direction were confirmed.
Moreover, the generation | occurrence | production state of the wrinkle in the point which released | stretched the stretched film from the holding part was confirmed visually.

  The film width in the stretching process (that is, the maximum width of the film) is 690 mm, and the ratio of reducing the film width (width reduction ratio) in the tension adjusting process is the width reduction ratio shown in Table 1. Formed.

  Moreover, the orientation angle of the stretched film and the retardation value of the stretched film were measured by KOBRA-WID manufactured by Oji Scientific Instruments.

The experimental results are shown below.
First, as shown in Table 1 and FIG. 3, in Examples 1 and 2 provided with a section for adjusting the tension, the variation in the orientation angle (orientation angle range) and the variation in the phase difference value (phase difference value range) are: Both are smaller than the comparative example. And in Example 2 where the exit width, that is, the width of the final stretched film is shorter than in Example 1, the variation in the orientation angle and the variation in the retardation value are smaller than in Example 1. .
Further, the wrinkles are generated in the comparative example, while the wrinkles are not generated in the first and second embodiments.

From the above results, it was confirmed that if the section for adjusting the tension is provided, the variation in the orientation angle and the variation in the retardation value in the width direction of the film can be reduced, and the generation of wrinkles in the film can be prevented.
In addition, it was confirmed that the variation in the orientation angle and the variation in the retardation value in the width direction of the film can be further reduced by increasing the ratio of narrowing the film width in the section for adjusting the tension. In other words, it was confirmed that the variation in the orientation angle and the variation in the retardation value in the width direction of the film can be reduced by reducing the tension of the film.

  The method for producing a stretched film of the present invention is a method for producing a retardation film used for optical compensation such as prevention of coloring, widening of a viewing angle, prevention of reflection of external light in an image display device such as a liquid crystal display device or an organic EL display device. Suitable for manufacturing.

EE Stretched film manufacturing equipment Hs Gripping means Hh Gripping means F Film BR Original roll MR Product roll P1 Stretching section P2 Tension adjusting section P3 Release section

Claims (4)

A film stretching method for stretching the film such that the molecular orientation axis is inclined with respect to the width direction of the film while moving the belt-like film in the longitudinal direction,
Stretching step of stretching the film by moving both ends of the film in the width direction at different moving speeds;
After the stretching step, while moving both ends in the width direction of the film at different moving speeds, the moving speed is low at the low speed side end so that the both ends in the width direction of the film approach each other. And a tension adjusting step of moving toward the high speed side end portion in order. In the tension adjustment step,
2. The film according to claim 1, wherein both end portions in the width direction of the film are brought close to each other until the width of the film is reduced by 0.1 to 25% with respect to the maximum width of the film in the stretching step. Stretching method. A method for producing a strip-like film having a molecular orientation axis inclined with respect to the width direction,
A method for producing a stretched film, comprising: stretching a band-shaped film by the film stretching method according to claim 1. It is a strip-shaped stretched film produced by the method for producing a stretched film according to claim 3, wherein the variation in the inclination of the molecular orientation axis in the width direction is within ± 1 ° with respect to the predetermined inclination. Characterized stretched film.