TWI648145B - Method and apparatus for manufacturing stretched film - Google Patents

Abstract

A method and apparatus for producing a stretched film. The film (15) is extended in the conveying direction by the difference in the circumferential speed of the pair of low speed rolls (21) on the upstream side and the pair of high speed rolls (22) on the downstream side. When the surface temperature of the high speed roller (22a) is T and the surface temperature of the film (15) which is in contact with the surface of the high speed roller (22a) is t, the near infrared ray line heater (23) is used, Temperature difference | Tt | is set to be less than or equal to 10 °C. More preferably, it is set to t=T. Since the temperature difference is reduced, it is possible to suppress cooling or heating when the film (15) is in contact with the high speed roller (22a). The shrinkage or expansion of the film (15) is reduced, thereby eliminating the unevenness of the extension caused by shrinkage or expansion.

Description

Method and device for manufacturing stretch film

The present invention relates to a method and a device for manufacturing a stretched film that extends a film in a transport direction by using a circumferential speed difference of a pair of rolls

In general, the production of a thermoplastic resin film is roughly classified into a solution-forming film method and a melt film forming method. In the solution film forming method, a dope obtained by dissolving a thermoplastic resin in a solvent is cast from a mold to, for example, a support for cooling a cylinder or a drying belt, and then peeled off to form a film. Further, in the melt film forming method, after the thermoplastic resin is melted by an extruder, it is extruded from a die to, for example, a support of a cooling cylinder, and then peeled off to form a film.

The thermoplastic film formed by the above method, for example, a fluoridation cellulose film, which generally extends in the longitudinal direction (transport direction) and the lateral direction (width direction), thereby exhibiting in-plane retardation (Re), thickness direction Delay (Rth). Thereby, when used as a retardation film of a liquid crystal display device, the viewing angle magnification can be achieved.

In the case of extending the thermoplastic film in the longitudinal direction, for example, using multiple preheating After the thermoplastic film is preheated by the roll, the film is stretched in the longitudinal direction by the circumferential speed difference of the pair of stretching rolls arranged separately in the conveying direction (see, for example, Patent Document 1). In this stretching process, the film is heated and longitudinally stretched by a preheating roll or a stretching roll or the like. Further, after longitudinal stretching, the film is cooled by a cooling roll and sent to the next step. In this way, heating or cooling is performed in a state where the respective rolls are brought into contact with the film, so that wrinkles are generated in the film width direction, or scratches are caused by the wrinkles.

For example, in Patent Document 1, in order to prevent the film from coming into contact with a plurality of preheating rolls, scratches or wrinkles are formed on the surface of the film, and the plurality of preheating rolls and the upstream side are made according to the temperature change before and after the contact of the film with each of the rolls. The peripheral speed of the stretching rolls is sequentially increased as they go downstream, and an appropriate tension is applied between the preheating rolls to suppress the occurrence of scratches or wrinkles. Further, in Patent Document 2, in the longitudinal extension, the contact time of the low-speed side stretching roller with the film is set to be 0.5 second or more and 2.5 seconds or less, and the surface temperature of the low-speed side stretching roller is set to be greater than or equal to Tg-6 ° C and less than or equal to Tg + 6 ° C, thereby suppressing the occurrence of peeling unevenness during longitudinal stretching.

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2008-213332

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2011-245624

Moreover, the recent liquid crystal display devices are required to be lightweight, thin, and high quality. A thin and high quality film of, for example, greater than or equal to 20 μm and less than or equal to about 60 μm is also required for the film to be used. In the case where such a thin film is longitudinally stretched, a method of preheating by a preheating roll such as Patent Document 1, or a surface temperature or film contact time by adjusting a low speed side stretching roll as in Patent Document 2 However, there is a limit in the method of suppressing unevenness of peeling, and there is a case where a solid depression or a scratch or wrinkle is generated on the surface of the film, and improvement is required.

In order to solve the above problems, an object of the present invention is to provide a method and an apparatus for producing a stretched film which can cope with film formation and which does not cause scratches or wrinkles on the film.

The following findings were obtained after careful research on the causes of the depression, scratches, or wrinkles accompanying the film formation. In the longitudinal stretching, the film is heated by contact of the film with the heated low-speed side stretching roll, and then the film is longitudinally extended by the difference in speed between the low-speed side stretching roll and the high-speed side extending roll. The film heated in contact with the low-speed side stretching rolls travels between the stretching rolls and comes into contact with the next high-speed side stretching rolls. At this time, if there is a temperature difference between the film in contact with the high-speed side extension roller and the high-speed side extension roller, the film is brought into contact with cooling or heating by the temperature difference. With this cooling or heating, shrinkage or expansion of the film occurs simultaneously with stretching, thereby causing uneven stretching. Since the stretching is uneven, the planarity of the entire film is deteriorated, and irregularities are caused. When such a film is brought into contact with the stretching roll and conveyed, it is found that, in addition to the occurrence of the depression on the entire surface of the film, the film is locally strongly rubbed, and scratches or wrinkles are formed on the film.

In the present invention, the film containing the strip-shaped thermoplastic resin is transported by a low-speed roll disposed on the upstream side in the transport direction of the film and disposed under the film. The circumferential speed difference of the high-speed roller on the side of the swim is extended to form a stretched film. When the surface temperature of the high speed roller is T, and the temperature of the film in contact with the high speed roller (that is, the surface temperature of the film at the contact portion of the film and the high speed roller) is t, the temperature difference |Tt | of the two is controlled to be less than or Equal to 10 ° C.

It is preferable to control the temperature of the film between the low speed roll and the high speed roll so that the film temperature t which is in contact with the high speed roll becomes the surface temperature T of the high speed roll. In the temperature control of the film between the low speed roller and the high speed roller, a film disposed between the near infrared ray line heater or the air blowing nozzle, the temperature adjusting roller, and the low speed roller and the high speed roller disposed in the width direction orthogonal to the conveying direction of the film is used. Heating chamber and the like.

Preferably, when the glass transition temperature of the film is set to Tg, the film is heated to a stretching temperature Te greater than or equal to Tg-20 ° C and less than or equal to Tg + 20 ° C by a low speed roller, and the film is cooled to be larger than by a high speed roller. Or equal to Tg-100 ° C and less than or equal to Tg - 5 ° C.

Preferably, the film is preheated to greater than or equal to Tg - 40 ° C and less than or equal to Tg - 5 ° C prior to longitudinal extension of the film, and the film is cooled by a chill roll in contact with the film after longitudinal stretching of the film. Further, it is preferable that the longitudinal extension aspect ratio obtained by dividing the length of the film transport direction between the low speed roller and the high speed roller by the film width before stretching is 0.01 or more and 3.0 or less.

In the production apparatus of the stretched film of the present invention, the film containing the strip-shaped thermoplastic resin is transported, and the film is longitudinally stretched by the difference in the circumferential speed of the low-speed roll disposed on the upstream side in the transport direction of the film and the high-speed roll disposed on the downstream side. Stretch film. The manufacturing apparatus of the stretched film includes a temperature control portion that is at a surface temperature of the high speed roller When T is set to T and the temperature of the film in contact with the high speed roller is t, the temperature difference |T-t | of both is controlled to be 10 ° C or less. More preferably, the temperature control unit controls the temperature of the film between the low speed roll and the high speed roll so that the film temperature t in contact with the high speed roll becomes the surface temperature T of the high speed roll.

According to the present invention, the temperature difference between the high-speed roll and the film in contact with the high-speed roll becomes small, and longitudinal extension of a film-like failure such as no dent, scratch, or wrinkle can be performed.

9‧‧‧Pre-process equipment

10‧‧‧Stretching film manufacturing equipment

11‧‧‧Preheating Department

12‧‧‧Longitudinal extension

13‧‧‧The Ministry of Cooling

14‧‧‧Next process installation

15‧‧‧ film

16‧‧‧Preheating roller pair

16a, 17, 18‧‧‧ preheating rolls

16b, 21b, 22b‧‧‧ clamping rolls

21‧‧‧Low speed roller pair

21a‧‧‧low speed roller

22‧‧‧High speed roller pair

22a‧‧‧High speed roller

23‧‧‧ Near Infrared Line Heater

23a‧‧‧Near infrared heater

23b‧‧‧ reflector

24, 51, 55, 59 ‧ ‧ temperature regulator (temperature regulator)

24a, 51a, 55a, 59a‧‧‧ temperature sensors

25, 26‧‧‧ chill roll

27, 28‧‧‧Transport roller

50‧‧‧Air supply nozzle

52, 58‧‧‧Air blower

53, 54, ‧ ‧ warm roll

56, 57‧‧‧ heating chamber

56a, 57a‧‧‧ labyrinth seals

61‧‧‧ slitting machine

61a, 61b‧‧‧ Roller

62‧‧‧Rotary cutter

Ls‧‧‧ length

Fig. 1 is a side view showing an outline of an example of a manufacturing apparatus of a stretched film of the present invention.

Fig. 2 is a side view showing an example of a longitudinally extending portion.

3 is a side view showing an example of a longitudinally extending portion of another embodiment in which a blowing nozzle is used.

4 is a side view showing an example of a longitudinally extending portion of another embodiment in which a temperature adjustment roller is used.

Fig. 5 is a side view showing an example of a longitudinally extending portion of another embodiment in which a heating chamber is used.

Fig. 6 is a side view showing an example of another embodiment in which a slitter is provided downstream of the longitudinally extending portion.

As shown in FIG. 1, the manufacturing apparatus 10 of the stretched film of the present invention includes a preheating portion 11, a longitudinally extending portion 12, and a cooling portion 13. In the manufacturing apparatus 10 of the stretched film, the front process unit 9 is connected to the inlet side, and the subsequent process apparatus 14 is connected to the outlet side. As the pre-process apparatus 9, there are a film forming apparatus, a film feeding apparatus, and the like which are not shown. As the film forming apparatus, a well-known solution film forming apparatus, a melt film forming apparatus, or the like can be used. Unlike the case where the film 15 is directly fed out from the film forming apparatus, the film feeding device extracts the film 15 from the wound film wound in a roll shape after the film forming, and supplies the film 15. As the subsequent process device 14, there is a cloth cliper or a film winding device used for laterally extending after longitudinal stretching. In the case where the lateral stretching is not continuously performed after the longitudinal stretching, the fabric tenter is omitted, and the film 15 is wound into a roll shape by a film winding device.

The film 15 to be stretched may be a thermoplastic resin film, and is, for example, a cellulose or a norbornene resin suitable for use in an optical film such as a retardation film, acrylic or polycarbonate.

The preheating unit 11 includes a preheating roller pair 16, a first preheating roller 17, and a second preheating roller 18. The preheating roller pair 16 has an inlet preheating roller 16a and a nip roller 16b, and the film 15 is sandwiched and conveyed. The film 15 is suspended by the inlet preheating roller 16a, the first preheating roller 17, and the second preheating roller 18, and is transferred. Thereby, the contact area of the film 15 and each of the preheating rolls 16a, 17, and 18 is increased, and preheating is performed efficiently.

The preheating temperature needs to be set to a temperature lower than the extendable temperature. Therefore, when the glass transition temperature of the film 15 is set to Tg, the film 15 is preheated to be greater than or equal to Tg - 40 ° C and less than or equal to Tg - 5 ° C or less, and the film 15 is sent to the longitudinally extending portion 12. Specifically, the film 15 is preheated to greater than or equal to Tg - 60 ° C and less than or equal to Tg - 35 ° C by the inlet preheating roller 16a, and the film 15 is further preheated to greater than or equal to Tg by the first preheating roller 17. The film 15 is further preheated to greater than or equal to Tg - 40 ° C and less than or equal to Tg - 5 ° C by a second preheat roll 18 at -50 ° C and less than or equal to Tg - 25 ° C.

The film 15 preheated to a fixed temperature by the preheating portion 11 is sent to the longitudinally extending portion 12. The vertical extension portion 12 includes a low speed roller pair 21 and a high speed roller pair 22. The low speed roller pair 21 has a low speed roller 21a and a nip roller 21b. The high speed roller pair 22 has a high speed roller 22a and a nip roller 22b.

In the low-speed roll 21a and the high-speed roll 22a, a temperature-regulating medium such as water, oil, steam, or the like is individually supplied from the temperature-regulating medium circulation unit. Each of the rolls 21a and 22a is set to a desired surface temperature by the cyclic supply of the temperature-modulating medium. For example, the low speed roller 21a is greater than or equal to Tg-20 ° C and less than or equal to Tg + 20 ° C, and the high speed roller 22a is greater than or equal to Tg - 100 ° C and less than or equal to Tg - 5 ° C. By setting such a temperature range, it is possible to perform uniform longitudinal stretching of the film 15 of 20 μm or more and 100 μm or less, and it is preferable to perform uniform longitudinal stretching of the film 15 of 20 μm or more and 60 μm or less, especially It is preferable to perform uniform longitudinal stretching of the film 15 of 20 μm or more and 40 μm or less.

As shown in FIG. 2, during the period from the film 15 fed from the low speed roller pair 21 to the high speed roller pair 22, the temperature is lowered by the influence of the ambient temperature such as room temperature. Therefore, when the film 15 comes into contact with the high speed roller 22a, a temperature difference is generated therebetween. When the temperature of the high speed roller 22a is lower than the temperature of the film 15 due to the temperature difference, the film 15 that is in contact with the high speed roller 22a is cooled by contact. Thereby, the shrinkage and extension of the film 15 are simultaneously produced, This results in uneven extension. In order to eliminate this temperature difference, the near-infrared line heater 23 is disposed close to the film 15 between the low speed roller 21a and the high speed roller 22a. Further, according to the manufacturing environment, and because the temperature difference causes the temperature of the high speed roller 22a to be higher than the temperature of the film 15, the film 15 in contact with the high speed roller 22a is heated by contact to cause expansion while extending. In this case, as will be described later, the air blowing nozzle 50 (see FIG. 3), the temperature adjusting roller 53, the temperature adjusting roller 54 (see FIG. 4), the heating chamber 56, the heating chamber 57 (see FIG. 5), and the like are used. The film 15 is cooled.

The near-infrared line heater 23 has a straight tubular near-infrared heater 23a and a reflector 23b. The reflector 23b accommodates the near-infrared heater 23a, and causes near-infrared light from the near-infrared heater 23a to be gathered in a line shape in the width direction on the film 15. In the present embodiment, the near-infrared line heater 23 is disposed on the upper side with respect to the film 15, but the arrangement position may be the lower side of the film 15, and may be disposed on the upper and lower sides with respect to the film 15. The near-infrared line heater 23 is disposed in the width direction of the film 15, so that the film 15 is uniformly heated linearly in the width direction of the film 15.

A temperature sensor 24a is disposed in the vicinity of the high speed roller 22a. The temperature sensor 24a measures the temperature of the film 15. The output of the temperature sensor 24a is sent to a temperature regulator (temperature regulator) 24. The temperature controller 24 controls, for example, the driving current of the near-infrared line heater 23 based on the temperature information of the film 15 from the temperature sensor 24a, and adjusts the amount of heat generated by the near-infrared line heater 23, and the film 15 The temperature t is controlled so as to become the surface temperature T of the high speed roller 22a. The temperature t of the film 15 is the surface temperature T of the high speed roller 22a, and means that, for example, the temperature difference between the temperature t of the film 15 and the surface temperature T of the high speed roller 22a is within ±1 °C. In addition, about to be high The film temperature t before the contact of the speed roller 22a depends on the surface temperature T of the high speed roller 22a, and also depends on the surrounding ambient temperature, the conveying speed of the film 15, the thermal conductivity of the film 15, the specific heat, the specific gravity, and the film thickness. . In the temperature adjustment of the temperature controller 24, temperature adjustment is preferably performed in consideration of the respective physical properties. Further, instead of using the temperature sensor 24a to measure the film temperature t, the film temperature t may be predicted based on the respective physical properties, and the temperature t of the film 15 may be the surface temperature T of the high speed roller 22a based on the predicted value. Take control. The temperature control unit is constituted by the near-infrared line heater 23, the temperature sensor 24a, and the temperature regulator 24.

As shown in FIG. 1, the extended film 15 is conveyed to the cooling part 13, and is cooled. The temperature-regulating medium is supplied to each of the cooling rolls 25 and the cooling rolls 26 individually from the temperature-regulating medium circulation portion, and each of the rolls 25 and 26 is set to a desired surface temperature. For example, the first cooling roll 25 is less than or equal to Tg - 40 ° C, and the second cooling roll 26 is less than or equal to Tg - 50 ° C. The cooled film 15 is sent to the subsequent process device 14 by the conveyance roller 27 and the conveyance roller 28.

Although not shown in the drawings, the roller 16a, the roller 17, the roller 18, the roller 21a, the roller 22a, the roller 25, and the roller 26 are connected to the motor, and are rotatable at a desired rotational speed. In the longitudinally extending portion 12, the film 15 is elongated in the conveying direction by the difference in the peripheral speed between the low speed roller 21a and the high speed roller 22a to obtain a longitudinal extension. The circumferential speed difference between the low speed roller 21a and the high speed roller 22a is appropriately changed depending on the stretching ratio, and is preferably set within a range of, for example, 2 m/min or more and 100 m/min or less.

When longitudinal stretching is performed, the longitudinal stretching ratio is preferably in a range of more than 1.0 and less than or equal to 3.0. In the range where the longitudinal stretching ratio is greater than 1.0 and less than or equal to 3.0 In this case, the occurrence of thickness unevenness can be satisfactorily suppressed, and the uneven distribution of the retardation is also suppressed.

Further, the longitudinal extension aspect ratio (Ls/W1) obtained by dividing the length Ls of the film 15 between the low speed roller 21a and the high speed roller 22a by the width W1 of the film 15 before stretching is preferably greater than or equal to 0.01 and less than or equal to 3.0. . The smaller the longitudinal extension aspect ratio is, the smaller the narrowing of the width contraction is, and the ratio of the uniform thickness portion at the center portion is increased in the film thickness distribution in the film width direction. Thereby, the width of both side edges of the film cut by the slitter 61 described later can be made small, and the center portion of the product can be enlarged by the amount of reduction, so that product loss can be suppressed. In order to reduce the longitudinal extension aspect ratio, it is preferable to suspend the film 15 on the low speed roller 21a and the high speed roller 22a. With this cross suspension, the Ls as the longitudinal extension span is reduced, and as a result, the longitudinal extension aspect ratio (Ls/W1) can be reduced.

The preheating portion 11 preheats the film 15 to be greater than or equal to Te-40 ° C, whereby the temperature rise amount when the film 15 is heated by the low speed roller 21a of the longitudinally extending portion 12 is not excessively large, so that the low speed roller 21a can be suppressed. Corrugated wrinkles are produced on the surface. Moreover, the film 15 is preheated by the preheating portion 11 to less than or equal to Tg - 5 ° C, whereby the film 15 is not extended in the preheating portion 11 so that the longitudinal extension portion 12 can be uniformly extended.

The film 15 extending longitudinally through the longitudinally extending portion 12 is wound into a film roll by, for example, a film winding machine of the subsequent process device 14.

Next, instead of heating the film 15 using the near-infrared line heater 23 shown in FIG. 2, as shown in FIG. 3, the heating air is blown to the film 15 by the air blowing nozzle 50, and the temperature of the film 15 is controlled. The air blowing nozzle 50 is disposed in the width direction orthogonal to the conveying direction of the film. In this case, the temperature sensor 51a obtains the upcoming The temperature information of the film 15 before the high speed roller 22a contacts, based on the temperature information, the temperature of the air from the blower 52 is adjusted by the temperature adjuster 51.

Further, as shown in FIG. 4, the temperature of the film 15 can also be controlled by bringing the temperature adjustment roller 53 and the temperature adjustment roller 54 circulating inside the temperature adjustment medium into contact with the film 15. The temperature adjustment roller 53 and the temperature adjustment roller 54 are disposed in the width direction orthogonal to the conveyance direction of the film, one is in contact with the upper surface of the film 15, and the other is in contact with the lower surface of the film 15. In this case, the temperature information of the film 15 immediately before the contact with the high speed roller 22a is also obtained by the temperature sensor 55a, and the temperature of the temperature adjustment roller 53 and the temperature adjustment roller 54 is controlled by the temperature controller 55 based on the temperature information. The temperature is adjusted such that the temperature t of the film 15 immediately before the contact becomes the surface temperature T of the high speed roller 22a. In addition, instead of the circulation of the temperature-regulating medium, a temperature-regulating roller with a built-in heater may be used.

Further, as shown in FIG. 5, the heating chamber 56, the heating chamber 57, the blower 58, and the temperature adjuster 59 may be used to control the temperature of the film 15 between the low speed roller pair 21 and the high speed roller pair 22. The upper heating chamber 56 has labyrinth seals 56a at the lower end covering the upper side of the membrane 15 between the pair of rollers 21, 22. The labyrinth seal 56a is disposed close to the upper end of the low speed roller 21a and the upper end of the nip roller 22b, thereby suppressing the outflow of air from the heating chamber 56. Similarly, the lower heating chamber 57 also has a labyrinth seal 57a at the upper end, covering the lower side of the membrane 15 between the pair of rollers 21, 22. A blower 58 and a temperature regulator 59 are connected to each of the heating chamber 56 and the heating chamber 57. The blower 58 supplies air to the heating chamber 56 and the heating chamber 57. The temperature controller 59 adjusts the temperature of the air from the blower 58 and sets the temperature of the film 15 to be the same as the surface temperature T of the high speed roller 22a. Therefore, close to the high speed roller 22a The temperature sensor 59a is configured. The temperature information from the temperature sensor 59a is input to the temperature adjuster 59, and the temperature of the air from the blower 58 is adjusted based on the temperature information.

In each of the above embodiments, the near-infrared line heater 23, the air blowing nozzle 50, the temperature adjusting roller 53, the temperature adjusting roller 54, the heating chamber 56, and the heating chamber 57 are used to constitute a temperature adjusting portion, that is, with the high speed roller 22a. The temperature t of the film 15 before the contact is adjusted to the surface temperature T of the high speed roller 22a. However, the temperature is not limited thereto. For example, the temperature t of the film 15 immediately before the contact with the high speed roller 22a can be controlled at T-10. °C≦t≦T+10 °C. Further, the near-infrared line heater 23, the air blowing nozzle 50, the temperature adjusting roller 53, the temperature adjusting roller 54, the heating chamber 56, and the heating chamber 57 are used individually to control the temperature of the film 15, but these may be combined as appropriate. Composition.

In each of the above embodiments, the surface temperature T of the high speed roller 22a is fixed, and the temperature t of the film 15 between the low speed roller pair 21 and the high speed roller pair 22 is changed to perform vertical extension, but it may be replaced by Alternatively, or in addition, the surface temperature T of the high speed roller 22a may be changed to control the temperature difference between the two. In this case, in order to change the surface temperature T of the high speed roller 22a, for example, the temperature adjustment medium is circulated in the high speed roller 22a, and the temperature of the temperature adjustment medium is controlled by the temperature regulator.

In the embodiment, the preheating roller 16a, the preheating roller 17, and the preheating roller 18 are used and the preheating of the film 15 is performed by direct contact. However, as the film 15 is thinned, the film 15 may be thermally expanded on the preheating roll 16a, the preheat roll 17, and the preheat roll 18 to have a corrugated shape. This corrugated expansion has the potential to cause wrinkles or scratches on the film 15. Therefore, it is also possible to replace the heat conduction in direct contact with the film 15, and the arrangement is not illustrated. The preheating chamber is provided with an air supply nozzle and an exhaust nozzle in the preheating chamber to heat the membrane 15. In this case, since the preheating roll 16a, the preheating roll 17, and the preheating roll 18 are not used, the corrugated expansion of the film 15 is suppressed.

In each of the above embodiments, the upstream side low speed roller pair 21 and the downstream side high speed roller pair 22 are vertically extended in one step, and the low speed roller pair 21 and the high speed roller pair 22 may be multi-staged as needed. The invention is embodied in a longitudinal extension of the manner. Further, the film 15 is suspended across the low speed roller 21a and the high speed roller 22a, but may be suspended in parallel. Further, the nip position of the nip roller can be appropriately changed.

A plurality of preheating chambers may be used, or one preheating chamber may be used as a preheating portion having a preheating zone divided into a plurality of partition walls in the film transport direction. Further, in the method of supporting the film of the preheating chamber, in addition to the use of the free roller, a turn bar which floats the film by the ejection of air may be used.

Further, as shown in FIG. 6, a slitter 61 may be provided between the longitudinally extending portion 12 and the cooling portion 13. The slitter 61 has a pair of roll cutters 61a and a roll cutter 61b, and cuts the film 15 in the conveyance direction. Thereby, the film 15 is cut away from the center part and both side edge parts in the width direction. The both side edge portions are sent to, for example, a rotary cutter 62, and are recycled as a raw material of the film 15 or the like. By using the slitter 61, the both side edges of the thick-walled film are removed by the influence of the neck extension, so that the film 15 is locally shrunk in the conveying direction during the cooling of the film 15. And the occurrence of irregularities. Thereby, the occurrence of scratches or wrinkles of the film 15 is suppressed during the cooling of the cooling roll 25 and the cooling roll 26.

[Examples]

A deuterated cellulose film is used as the film 15, and preheating, longitudinal stretching, and cooling are performed. In the vertical extension portion 12, the upstream side low speed roller pair 21 and the downstream side high speed roller pair 22 are vertically extended in one stage. A film feeder was used as the pre-process apparatus 9, and the film 15 was taken out from the film roll and sent to the preheating section 11, and the film winding machine was used as the subsequent process apparatus 14, and the film 15 was wound up to form a film roll. The preheating temperature was set to 120 ° C, the extension temperature was set to 150 ° C, the stretching ratio was set to 1.5 times, the extension length was set to 300 mm, the cooling temperature was set to 100 ° C, the film conveyance speed was set to 2 m/min, and the film width W1 before stretching was obtained. The experiment was carried out by setting the film thickness to 600 mm, the film thickness before stretching to 100 μm, and the film width after stretching to 580 mm.

The temperature of the low speed roller 21a is set to 150 ° C, and the temperature T of the high speed roller 22a is 120 ° C, 130 ° C, 135 ° C, 140 ° C, 145 ° C, 150 ° C, 160 ° C, that is, the film 15 immediately before contact with the high speed roller 22a. The experiment was carried out by setting the temperature t to 135 ° C, 140 ° C, and 145 ° C. The experimental results are shown in Table 1.

As shown in Table 1, in the case of Examples 1 to 3 in which the difference between the temperature T of the high speed roller 22a and the temperature t of the film 15 was "0", no wrinkles or scratches were formed on the film after winding. Wrinkles. Further, in the case of Example 4 and Example 5 in which the difference was "10 ° C", only minute depressions were formed on the film, and there was no problem in practical use, and no scratches or wrinkles were formed on the film. On the other hand, in the case where the difference between the temperature T of the high speed roller 22a and the temperature t of the film 15 is "20 ° C", the film after winding is on the film. There are depressions, scratches, and wrinkles. Further, with respect to the depression, the displacement of the film surface was detected in the film migration direction by a non-contact type two-dimensional displacement meter, and NG (bad) was evaluated when the obtained maximum value (max) - minimum value (min) exceeded 0.5 mm. The maximum value is the value at the highest point when the film is observed as a whole, and the minimum value is the lowest value. For the scratch, it was evaluated by a microscope, and when the width was 1 μm or more and the depth was 0.01 μm or more, it was evaluated as NG. The wrinkles were evaluated as NG as long as they were visually observed.

Claims (17)

In a method of producing a stretched film, a film containing a strip-shaped thermoplastic resin is transported, and the film is longitudinally formed by a difference between a low speed roll disposed on the upstream side in the transport direction of the film and a high speed roll disposed on the downstream side. Extending to manufacture a stretched film, the method of manufacturing the stretched film comprising: when the surface temperature of the high speed roll is set to T, and the temperature of the film before contact with the high speed roll is set to t, The temperature difference | Tt | is controlled to be less than or equal to 10 ° C. The method for producing a stretched film according to claim 1, wherein the low-speed roll and the temperature t of the film before the contact with the high-speed roll are the surface temperature T of the high-speed roll The temperature of the film between the high speed rolls is controlled. The method for producing a stretched film according to claim 2, wherein the temperature control of the film between the low speed roll and the high speed roll is to heat the film using a near infrared line heater, The near-infrared line heater is disposed in a width direction orthogonal to the conveying direction of the film. The method for producing a stretched film according to claim 2, wherein the temperature control of the film between the low speed roll and the high speed roll is performed by heating air from a blowing nozzle to heat the film. The air blowing nozzle is disposed in a width direction orthogonal to a conveying direction of the film. The method for producing a stretched film according to claim 2, wherein the temperature control of the film between the low speed roll and the high speed roll is performed by using a temperature adjusting roll The film is heated by contact, and the temperature-regulating roller is disposed in a width direction orthogonal to a conveying direction of the film. The method for producing a stretched film according to claim 2, wherein the temperature control of the film between the low speed roll and the high speed roll is to heat the film by a heating chamber, the heating chamber A chamber covers the membrane between the low speed roller and the high speed roller. The method for producing a stretched film according to any one of claims 1 to 5, wherein, when the glass transition temperature of the film is set to Tg, the film is heated to be greater than or by the low speed roller. An extension temperature Te equal to Tg-20 ° C and less than or equal to Tg + 20 ° C, and the film is cooled to greater than or equal to Tg - 100 ° C and less than or equal to Tg - 5 ° C by the high speed roller, the high speed roller The temperature at which the film is cooled is below the temperature at which the low speed roll heats the film. The method for producing a stretched film according to claim 7, wherein the film is preheated to be greater than or equal to Tg - 40 ° C and less than or equal to Tg - 5 ° C before the longitudinal extension of the film, and After longitudinal extension of the film, the film is cooled using a chill roll in contact with the film. The method for producing a stretched film according to claim 1, wherein a longitudinal extension aspect ratio obtained by dividing a length of a film transport direction between the low speed roll and the high speed roll by a film width before extending is greater than Or equal to 0.01 and less than or equal to 3.0. A manufacturing apparatus of a stretched film, which conveys a film containing a strip-shaped thermoplastic resin, and is disposed at a lower speed roller disposed on the upstream side in the transport direction of the film a peripheral speed difference of the high-speed roller on the swimming side, the film is longitudinally extended to manufacture a stretched film, and the manufacturing apparatus of the stretched film includes: a temperature control portion, wherein the surface temperature of the high speed roller is set to T, When the temperature of the film before the high-speed roll contact is set to t, the temperature difference |Tt | of both is controlled to be 10 ° C or less. The apparatus for manufacturing a stretched film according to claim 10, wherein the temperature control unit heats the film using a near-infrared line heater, and the near-infrared line heater is disposed to be transported to the film. The direction is orthogonal to the width direction. The apparatus for manufacturing a stretched film according to claim 10, wherein the temperature control unit heats the film by a heated air from a blower nozzle, and the blower nozzle is disposed in a direction in which the film is conveyed. In the width direction of the intersection. The apparatus for manufacturing a stretched film according to claim 10, wherein the temperature control unit heats the film by contact with a temperature adjustment roller, and the temperature adjustment roller is disposed in a transport direction with the film. Orthogonal width direction. The apparatus for manufacturing a stretched film according to claim 10, wherein the temperature control portion heats the film by a heating chamber that covers the low speed roller and the high speed roller The film. The apparatus for manufacturing a stretched film according to any one of claims 10 to 14, wherein when the glass transition temperature of the film is set to Tg, the film is heated to be greater than or by the low speed roller. An extension temperature Te equal to Tg-20 ° C and less than or equal to Tg + 20 ° C, using the high speed roller to cool the film to greater than or equal to Tg-100 ° C and less than or equal to Tg - 5 ° C, the temperature at which the high speed roll cools the film is below the temperature at which the low speed roll heats the film. The apparatus for manufacturing a stretched film according to claim 15, further comprising: a preheating portion that preheats the film to be greater than or equal to Tg - 40 ° C before extending the film in the conveying direction. And less than or equal to Tg - 5 ° C; and a cooling portion that cools the film by a cooling roll that is in contact with the longitudinally extending film. The apparatus for manufacturing a stretched film according to claim 10, wherein a longitudinal extension aspect ratio obtained by dividing a length of a film transport direction between the low speed roll and the high speed roll by a film width before extension is greater than Or equal to 0.01 and less than or equal to 3.0.