JP2013014083A - Apparatus for forming optical film, and method of forming optical film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for forming an optical film which forms an optical film and winds the formed film in a roll shape thereby forming the optical film by a melt extrusion method without causing a black band.SOLUTION: The apparatus for forming the optical film by the melt extrusion method includes: a melt extrusion part 1A which extrudes a melt containing at least a thermoplastic resin and an additive as a film like melt from a T-die 1A2 having a plurality of a lip gap adjustment means 1A27; a cooling receiving part having at least a touch roll 1B2 and a cast roll 1B1; and a winding part. The apparatus for forming the optical film is characterized in that, after forming the film while moving one of the T-die 1A2 and the cooling receiving part to a TD direction, the film is wound in the roll shape in the winding part.

Description

  The present invention relates to a method for producing an optical film by a melt extrusion method. More specifically, the present invention relates to an optical film manufacturing apparatus and an optical film manufacturing method in which a black band or a black band does not occur even when an optical film manufactured by a melt extrusion method is wound into a long (several thousand meters) roll. .

  In recent years, various display devices such as a liquid crystal television, a plasma display (PDP), and an organic EL display have been developed, and these display devices are required to be thin and lightweight. In connection with this, the optical film used for a display is also required to be thin. In the production of optical films, it is also desired to increase the winding length per roll in order to increase transportation efficiency and reduce the frequency of switching in subsequent processes.

  However, in a film wound in a long (several thousand m) roll (hereinafter also referred to as a roll film), a high band-shaped portion occurs on the circumference of the roll film. It may cause a phenomenon that is called. The black band or the black band 6 is considered to be generated due to partial contact and deformation due to overlapping of a film having a wide film thickness when the film is wide and rolled up.

  When a black band occurs, the film surface of the adhesion part deforms and wrinkles, causing a coating failure when a functional layer is applied in the subsequent process, and bonding when bonding with other films. It causes failure such as defects. In particular, it causes a fatal defect when used as an optical film.

  Conventionally, as one method for producing an optical film, a resin composition containing a thermoplastic resin and an additive is melted by an extrusion device, then extruded from a T die into a film shape, cooled and solidified to form a film, so-called melt extrusion The law is known.

  The film thickness adjusting means for manufacturing an optical film by the melt extrusion method is the adjustment of the film thickness inline when adjusting the lip interval of the T die with the film thickness adjusting bolt attached to the T die or more precisely. A method of measuring and measuring the thickness of the lip is finely adjusted using a heat bolt or the like. However, since film thickness adjusting bolts, heat bolts, and the like are installed at a certain interval, it is not possible to adjust the film thickness below these intervals. In addition, there is a physical restriction in order to make the interval between these adjusting means close, and the manufacturing cost of the T dice increases. Also, it is difficult to completely adjust the unevenness in micron units for smoothing.

  On the other hand, Japanese Patent Application Laid-Open No. 2004-149639 also discloses a method of smoothing the surface by cooling the film while pressing it with a pair of rolls after melt film formation. In this method, convex portions having a relatively narrow width of several mm or less, such as die streaks, can be corrected and smoothed, but it is difficult to correct widths beyond that.

  For this reason, when a long roll film is prepared in the melt extrusion method, there is a tendency that a black band or a black band is easily generated.

  On the other hand, when an optical film is wound into a roll shape, a method for devising winding and preventing the generation of a black band or a black band has been studied so far. For example, a method is known in which a film when wound up is embossed at both ends of the width to prevent the film from sticking (see, for example, Patent Document 1).

  However, in the method described in Patent Document 1, it has been found that it is difficult to add a large knurl (emboss) if the film thickness is thin, and that the effect of preventing a black band is small if the knurl is low.

  A method is known in which a press roll is used during film winding to eliminate a gap between the films and prevent winding of a specific portion (for example, see Patent Document 2).

  However, in the method described in Patent Document 2, when a pressure roll is used at the time of winding, since the elasticity of the film is low when the film thickness is thin, the followability at the time of winding is high, and the gap between the films is low. On the contrary, it has been found that the roll wound in a long length has a large unevenness in the width and the pressing point of the pressing roll is limited, so that the improvement effect of the black band or the black band is poor.

  When winding a film, a method of changing the winding tension in accordance with the winding length is known (for example, see Patent Document 3).

  However, according to the method described in Patent Document 3, it has been found that a black band or a black band cannot be prevented only by a change in the winding tension as the film to be manufactured becomes longer.

  A method of changing the winding axis in the axial direction intermittently or periodically at the time of winding the film is known (for example, see Patent Document 4).

  However, in the method described in Patent Document 4, in the case of a thin film having low elasticity, there is a high possibility of inducing lateral wrinkles, and a sudden change may cause breakage due to tension at the end. I understood.

  From the above situation, it is hoped to develop a method for producing an optical film that does not generate a black band or a black band (hereinafter also simply referred to as a black band) when an optical film is formed into a roll by roll extrusion by the melt extrusion method. It is rare.

JP 2002-068538 A Japanese Patent No. 4414576 JP 2003-176068 A JP 2010-150041 A

  The present invention has been made in view of the above situation, and as an object thereof, an optical film manufacturing apparatus in which a black band does not occur when an optical film is formed into a roll by a melt extrusion method. Is to provide.

  The above object of the present invention can be achieved by the following constitution.

1. A melt extrusion section for extruding a melt containing at least a thermoplastic resin and an additive as a film-like melt from a T die having a plurality of lip gap adjusting means; and a cooling take-up section having at least a touch roll and a cast roll In the manufacturing apparatus of the melt extrusion type optical film having a winding part,
An apparatus for producing an optical film, wherein either one of the T dice or the cooling take-up part is formed while moving in the TD direction, and then wound into a roll shape by the take-up part.

2. A melt extrusion section for extruding a melt containing at least a thermoplastic resin and an additive as a film-like melt from a T die having a plurality of lip gap adjusting means; and a cooling take-up section having at least a touch roll and a cast roll In an optical film manufacturing method for manufacturing an optical film by a melt extrusion type film manufacturing apparatus having a winding part,
An optical film manufactured by forming one of the T die and the cooling take-up part while moving in the TD direction, and then producing a roll-up optical film at the take-up part. Production method.

  3. When the maximum value of the movement width T in the TD direction of the cooling take-up section or the T die is Tmax and the interval between the plurality of lip gap adjusting means is R, the following relationship is obtained. The method for producing an optical film as described in 2 above.

0.75R <Tmax
4). When the optical film is wound up by the winding unit and a plurality of roll-shaped optical films are continuously manufactured, when the time for manufacturing one roll-shaped optical film is Lt, the T dice, or The movement of the cooling take-up unit in the TD direction is moved in the same direction during the Lt, and when the next roll-shaped optical film is manufactured, the T dice or the cooling take-up unit 4. The method for producing an optical film as described in 2 or 3 above, wherein the movement in the TD direction is set in a direction opposite to that when the immediately preceding roll-shaped optical film is produced.

  5). When the optical film is wound up at the winding section and a plurality of roll-shaped optical films are continuously manufactured, when the time for manufacturing one roll-shaped optical film is Lt, the T dice or the When the next roll-shaped optical film is manufactured by moving the movement in the TD direction of any one of the cooling take-up portions in the same direction during the Lt, the T dice or the cooling take-up The part is returned to the position where the previous roll-shaped optical film was manufactured, moved in the same direction as when the previous roll-shaped optical film was manufactured, and returned to the position where the previous roll-shaped optical film was manufactured. 4. The method for producing an optical film as described in 2 or 3 above, wherein the winding portion until the time is discarded.

  6). When the optical film is wound up by the winding unit and a plurality of roll-shaped optical films are continuously manufactured, when a time for manufacturing one roll-shaped optical film is Lt, T dice or cooling drawing is performed. The movement of any one of the take-up portions in the TD direction is reversed during the Lt, and the movement of the T dice or the cooling take-up portion in the TD direction is reversed at a cycle of Lt × 0.5 or less. The method for producing an optical film as described in 2 or 3 above.

  7). 7. The method for producing an optical film according to any one of 2 to 6, wherein both ends of the film are cut off at fixed positions after passing through the cooling take-up portion.

  8). The film manufacturing apparatus includes a film thickness measuring device for the optical film, and the lip gap is adjusted by the lip gap adjusting means according to the measurement result of the film thickness measuring apparatus. 2. A method for producing an optical film according to item 1.

  9. The film thickness of the optical film when wound by the winding unit is 10 μm or more and 25 μm or less, and the length of the optical film wound in the roll shape is 4000 m or more and 35000 m or less. The method for producing an optical film as described in any one of 2 to 6 above.

  When the optical film is formed into a roll by the melt extrusion method, a production apparatus for an optical film that does not generate a black band can be provided.

It is a schematic diagram of a manufacturing apparatus that uses a thermoplastic resin containing a thermoplastic resin and additives, melts it with a melt extruder, extrudes it into a film shape from a T-die, cools and solidifies it, and manufactures a take-up roll-shaped optical film. is there. FIG. 2 is an enlarged schematic view of a portion indicated by S in FIG. 1.

  Embodiments of the present invention will be described with reference to FIGS. 1 and 2, but the present invention is not limited thereto.

  The optical film manufacturing method of the present invention is manufactured by moving one of a T die and a cooling take-up portion in a TD (Transverse Direction) direction when manufacturing an optical film by a melt extrusion type film forming apparatus. By forming the film, generation of a black band appearing on the peripheral surface of the optical film wound up in a roll shape at the winding portion is prevented.

  Fig. 1 shows production using a thermoplastic resin containing thermoplastic resin and additives, melted with a melt extruder, extruded as a film from a T-die, and then cooled and solidified to produce an optical film in the form of a take-up roll It is a schematic diagram of an apparatus.

  In the figure, reference numeral 1 denotes a film production apparatus for producing a roll-shaped optical film. The film manufacturing apparatus 1 includes a melt extrusion unit 1A, a cooling take-up unit 1B, a stretching unit 1C, a winding unit 1D, a film thickness measuring device 1E, and a slitter 1F.

  Either one of the melt-extrusion part 1A or the cooling take-up part 1B has a moving means (not shown) so that it can move in the TD direction orthogonal to the transport direction of the optical film. The movement of the melt extrusion part 1A or the cooling take-up part 1B will be described with reference to FIG.

  The melt-extruded portion 1A includes a hopper 1A11 that supplies a thermoplastic resin composition containing a thermoplastic resin or additive for film, a gear pump 1A12 that stably feeds a melt containing the thermoplastic resin or additive, and a T-die 1A2. A melt extruder 1A1 having a supply pipe 1A13 and a filter 1A14 to be fed to the slab, and a melt containing a thermoplastic resin or additive sent from the melt extruder 1A1 from the tip lip gap (extrusion port) into a film form It has a T die 1A2 to be extruded as the product 2.

  The T die 1A2 has a lip gap adjusting means for adjusting a lip gap (extrusion port) 1A261 (see FIG. 2) in the width direction. The T dice 1A2 are classified into a coat hanger type and a straight manifold type, but there is no particular limitation in the present invention, and it can be appropriately selected depending on the resin used. Further, it may be for a single layer or a multilayer.

  The hopper 1A11 is charged with a thermoplastic resin composition containing a thermoplastic resin or an additive. The thermoplastic resin composition containing the thermoplastic resin or additive to be added is preferably dried in advance. The additives include physicochemical properties of the thermoplastic resin, and include, for example, plasticizers, ultraviolet absorbers, retardation control agents, peelability improvers, antioxidants, thermal decomposition inhibitors and the like.

  There is no restriction | limiting in particular as melt extruder 1A1, It is possible to use the melt extruder used for extrusion molding of a thermoplastic resin. For example, a single screw type extruder, a same direction rotating twin screw type extruder, a different direction rotating twin screw type extruder, a tandem type extruder and the like can be cited as representative examples.

  The filter 1A14 is not particularly limited. For example, a single-layer metal mesh made of an alloy such as stainless steel called a screen mesh, a metal mesh made of an alloy such as stainless steel, and a sintered metal filter in which each layer is sintered, Examples include sintered metal fiber filters that sinter the contact points between fibers using a wire mesh that is knitted with fine fibers, and sintered metal filters that sinter metal powder. It is preferable to use it.

  The cooling take-up unit 1B includes a cast roll 1B1, a touch roll 1B2, auxiliary cooling rolls 1B3 and 1B4, and a peeling roll 1B5.

  The film-like product 2 extruded by the T-die 1A2 and cast on the cast roll 1B1 is pressed to the cast roll 1B1 side by the touch roll 1B2 and formed into a film shape. The melt formed into a film is cooled and solidified by the auxiliary cooling rolls 1B3 and 1B4, peeled off from the peeling roll 1B5, becomes an unstretched film 2a, and is transported to the stretching section 1C by a plurality of transporting rolls 1C12. Although this figure shows the case where the auxiliary cooling rolls 1B3 and 1B4 are provided, the auxiliary cooling rolls 1B3 and 1B4 can be arranged as required, and the number of auxiliary cooling rolls is as required. Can be increased or decreased.

  As the touch roll 1B2, it is preferable to use an elastic roll. The elastic roll is not particularly limited. For example, the elastic roll is disposed inside a flexible metal sleeve, and has a double structure of a metal outer cylinder and an inner cylinder so that a cooling fluid can flow between them. And the like having a space. By using the elastic roll, the film-like melt extruded from the T dice 1A2 can be uniformly pressed to the cast roll 1B1 side, and the film thickness can be made uniform.

  The surface temperature of the touch roll 1B2 is preferably lower than the glass transition temperature (Tg) of the film-like melt. If it is higher than Tg, the peelability between the film-like melt and the touch roll 1B2 may be inferior. More preferably, it is Tg-50 degreeC to Tg.

  The cast roll 1B1 is not particularly limited, but is a roll having a structure in which a heat medium or a coolant that allows temperature control to flow inside is a highly rigid metal roll, and the size is not limited, but it is extruded from the T-die 1A2. The diameter of the cast roll 1B1 is usually about 100 mm to 1 m as long as it is sufficient to cool the formed film-like material. Examples of the surface material of the cast roll 1B1 include carbon steel, stainless steel, aluminum, and titanium. Further, in order to increase the surface hardness or improve the releasability from the resin, it is preferable to perform a surface treatment such as hard chrome plating, nickel plating, amorphous chrome plating, or ceramic spraying.

  In consideration of the smoothness of the obtained film, the surface roughness of the cast roll 1B1 is preferably 0.1 μm or less, more preferably 0.05 μm or less, in terms of arithmetic average roughness Ra. Of course, it is preferable to further polish the surface that has been subjected to surface processing so as to have the above-described surface roughness.

  The surface temperature of the cast roll 1B1 is determined based on the glass transition temperature (Tg) of the film-like product 2 in consideration of the peelability of the film formed by being pressed by the touch roll 1B2 on the cast roll 1B1 and the solidification property of the film-like product 2. ) To Tg-50 ° C. or more and Tg or less. Moreover, it is preferable that the surface temperature of auxiliary | assistant cooling roll 1B3 and 1B4 which comprises the cooling taking-up part 1B is also the same as the surface temperature of cast roll 1B1.

  The extending portion 1C includes an MD (Machine Direction) extending portion 1C1 and a TD (Transverse Direction) extending portion 1C2.

  The MD stretching unit 1C1 is peeled from the auxiliary cooling roll 1B4, and includes a transporting roll 1C12 that transports the obtained unstretched film 2a, and an MD stretching apparatus 1C11 that MD-stretches the transported unstretched film 2a. Yes.

  The MD stretching device 1C11 is not particularly limited. For example, the MD stretching device 1C11 has a heating device such as a plurality of transport rolls (not shown), an infrared heater (not shown), a hot air blowing device (not shown), and a glass transition of a thermoplastic resin. Heating is performed within the range of the temperature Tg to the glass transition temperature Tg + 100 ° C., and MD stretching can be performed in one or more stages depending on the speed difference between the rolls. The stretching ratio in the MD stretching portion 1C1 can be appropriately adjusted according to the use of the optical film to be manufactured.

  The TD stretching unit 1C2 includes a plurality of transport rolls 1C22 that transports the stretched film 2b MD stretched by the MD stretching unit 1C1, a TD stretching device 1C21 that TD stretches the film 2b, and a plurality of transports the TD stretched film 2c. Transport roll 1C22.

  The TD stretching device 1C21 includes a heating device such as a tenter stretching device (not shown), an infrared heater (not shown), a hot air blowing device (not shown), and the glass transition temperature Tg + 100 from the glass transition temperature Tg of the thermoplastic resin. It is possible to heat within the range of ° C. and perform TD stretching. The TD stretching apparatus 1C21 has a residual heat zone (not shown), a stretching zone (not shown), and a relaxation zone (not shown). The temperature is adjusted in accordance with the resin of the optical film to be manufactured, and the width is sequentially reduced toward the downstream side. It is designed to stretch and stretch. The tenter stretching apparatus is not particularly limited, and examples thereof include a clip tenter and a pin tenter, and can be selected and used as necessary.

  After extending | stretching to the width | variety and thickness which are required in TD extending | stretching part 1C2, the state extended | stretched by the heat setting process (not shown) in TD extending | stretching part 1C2 is fixed. The stretching ratio in the TD stretching section 1C2 can be appropriately adjusted according to the use of the optical film to be manufactured.

  In addition, there is no limitation in particular as the film manufacturing apparatus 1, MD (Machine Direction) extending | stretching part 1D and TD (Transverse Direction) extending | stretching part 1E which are shown by this figure can be arrange | positioned as needed. .

  In the winding unit 1D, the stretched film 2c TD-stretched by the TD stretching unit 1C2 is wound around the winding core. The winding unit 1D has a winding device 1D1, and when the amount of the optical film manufactured in one lot is large, the winding unit 1D is continuously divided into a plurality of rolls while switching, and is wound into a roll shape. Optical films are being manufactured.

  The film manufacturing apparatus shown in this figure has a slitter 1F that cuts out (trimming) unnecessary portions at both ends of the film at a fixed position after passing through the cooling take-up section. The position where the slitter 1F is disposed is not particularly limited. For example, the slitter 1F is preferably disposed before entering the MD stretching portion 1C1, before entering the TD stretching portion 1C2, and before embossing. By removing unnecessary portions at both ends, the balance with respect to the stress in the film becomes uniform, and the accuracy of MD stretching, TD stretching, and embossing processing is improved.

  The position where the film thickness measuring device 1E is disposed is preferably after passing through the cooling take-up section 1B, and particularly preferably immediately after being peeled off from the auxiliary cooling roll 1B4 by the peeling roll 1B5. The film thickness measuring apparatus 1E has a control mechanism (not shown) for adjusting the lip gap (extrusion port) 1A261 (see FIG. 2). Using the information of the film thickness measuring device 1E and adjusting the lip gap (extrusion port) 1A261 (see FIG. 2), the T die 1A2 or the cooling take-up portion 1B is orthogonal to the transport direction of one of the optical films. A method for controlling movement in the TD direction will be described later.

  It is preferable to dispose (process) an embossing device (not shown) for providing an uneven pattern for at least both ends of the film 2c to prevent winding, prevent scratches, and the like before being wound by the collecting unit 1D.

  The effect of the present invention is manifested in a thin film and a long length. The thickness of the optical film wound up by the winding unit 1D is preferably 10 μm to 25 μm, and the length of one optical film wound up is preferably 4000 m or more. From the viewpoint of handling, the core strength is preferably 20,000 m or less.

  FIG. 2 is an enlarged schematic view of a portion indicated by S in FIG. FIG. 2A is an enlarged schematic perspective view of a portion indicated by S in FIG. FIG. 2B is a schematic cross-sectional view along AA ′ in FIG. FIG.2 (c) is a partial schematic enlarged front view by the side of the adjustment bolt of T dies shown by Fig.2 (a).

  In the figure, 1A2 indicates a T die, and 1A13 indicates a supply pipe for supplying a melt containing a thermoplastic resin or an additive to the T die 1A2 from a melt extruder 1A1 (see FIG. 1).

  1B2 indicates a touch roll, and 1B1 indicates a cast roll. 1A21 represents one block constituting the T dice 1A2, and 1A22 represents the other block constituting the T dice 1A2. 1A23 indicates a side plate for fixing the block 1A21 and the block 1A22. Reference numeral 1A24 denotes a supply port for a melt containing a thermoplastic resin or additive sent from the supply pipe 1A13. 1A25 indicates a manifold formed between the block 1A21 and the block 1A22, and is provided in the width direction of the T dice 1A21. The melt containing the thermoplastic resin or additive supplied from the supply port 1A24 is temporarily stored in the manifold 1A25 via the supply pipe 1A241. Reference numeral 1A26 denotes a slit through which the melted material containing the thermoplastic resin or additive stored in the manifold 1A25 is converted into a film-like material 2 and is extruded from the lip gap (extruding port) 1A261, and between block 1A21 and block 1A22 Is formed.

  The cross-sectional shape of the manifold 1A25 is such that a uniform hydraulic pressure is applied to the slit 1A26, and a uniform flow of the melt containing the thermoplastic resin or additive in the width direction is obtained, and the thermoplastic resin or additive is included. The shape is not particularly limited as long as the melt does not stay, and examples thereof include a circle and a polygon.

  Reference numeral 1A27 denotes a lip gap adjusting means for adjusting the width of the lip gap (extrusion port) 1A261, and a plurality of lip gap adjusting means are arranged along the width direction of the block 1A21. As a result, the thickness of the lip gap (extrusion port) 1A261 of the T die 1A2 and the extruded film can be adjusted to be substantially uniform in the width direction. R represents the distance between the lip gap adjusting means, and the distance from the center of each lip gap adjusting means.

  The lip gap adjusting means is not particularly limited, and examples thereof include an adjustment bolt that adjusts the lip gap using a servo motor, and a heat adjustment bolt that adjusts the lip gap by expansion and contraction of the adjustment bolt by heating and cooling.

  In addition, it is preferable to install independent heating means (not shown) in the block 1A21 constituting the slit 1A26 and the block 1A22, and to control them at different temperatures.

  As one form of this invention, T dice | dies 1A2 are moved to the TD direction (C arrow direction) which cross | intersects at right angles with the conveyance direction (MD direction) of an optical film by a moving means (not shown). As another embodiment of the present invention, the cooling take-up unit 1B moves in the TD direction (C arrow direction) that intersects at right angles to the transport direction (MD direction) of the optical film.

  As a moving means for moving in the TD direction (C arrow direction), for example, a linear motor, a ball screw, an electric cylinder, a rack and pinion, etc. are hung or placed on a rail in the TD direction. It can be moved with.

  The moving means of the T dice 1A2 or the melt extruding part 1A and the melt extruding part 1A has a control mechanism (not shown), and a roll-shaped optical film is input in advance to produce a single roll-shaped optical film. The movement of the T die 1A2 or the melt-extrusion part 1A is controlled according to the time, the movement distance, and the movement method.

  In the manufacturing apparatus 1 shown in FIGS. 1 and 2, either the T dice 1 </ b> A <b> 2 or the cooling take-up unit 1 </ b> B is formed while the optical film is wound up by the winding unit 1 </ b> D to manufacture one roll-shaped optical film. One of them is moved by each moving means in the TD direction (C arrow and D arrow directions in FIG. 2) intersecting at right angles to the MD direction.

  By moving, the position of the film thickness part generated in the width direction of the optical film is different, and it is possible to avoid that the film thickness parts in the width direction of adjacent optical films overlap each other when winding, Occurrence can be prevented.

  When the maximum value of the movement width in the TD direction of the T dice 1A2 or the cooling take-up part 1B is Tmax, which is the interval R of the lip gap adjusting means 1A27 of the T dice 1A2, the film thickness part in the width direction of the adjacent optical film It is preferable to have the relationship expressed by the formula 1) in consideration of the overlap with the above, the reduction width in the trimming process, the cost, and the like.

Formula 1) 0.75R <Tmax
Next, the manufacturing method 1 shown in FIG. 1 is used to move the T dice 1A2 or the cooling take-up unit 1B in the TD direction when the roll unit 1D is wound up to manufacture a plurality of roll-shaped optical films. Will be described.

Movement method 1
When the roll-shaped optical film is continuously manufactured, when the time for manufacturing one roll-shaped optical film is Lt, the movement of the T dice 1A2 or the cooling take-up portion 1B in the TD direction is between Lt. When the next roll-shaped optical film is manufactured within the range satisfying the formula 1), the movement in the TD direction of either the T die 1A2 or the cooling take-up portion 1B is changed to the immediately preceding roll. The direction is the same as when the optical film was manufactured. Thereafter, when a roll-shaped optical film is continuously produced, the movement of either the T dice 1A2 or the cooling take-up unit 1B in the TD direction is alternately performed.

Movement method 2
As described above, when the time for producing one roll-shaped optical film is Lt, the movement in the TD direction of either the T die 1A2 or the cooling take-up portion 1B satisfies the expression 1) during Lt. When the next roll-shaped optical film is manufactured by moving in the same direction in the range, the T dice 1A2 or the cooling take-up portion 1B is returned to the position when the previous roll-shaped optical film was manufactured, The part rolled up in the same direction as when the roll-shaped optical film was manufactured and wound until the T-die 1A2 or the cooling take-up part 1B is returned to the position when the previous roll-shaped optical film was manufactured is Discard. Thereafter, when the roll-shaped optical film is continuously produced, the above method is repeated for the movement of the T dice 1A2 or the cooling take-up portion 1B in the TD direction.

Movement method 3
As described above, when the time for producing one roll-shaped optical film is Lt, the movement in the TD direction of either the T die 1A2 or the cooling take-up portion 1B satisfies the expression 1) during Lt. This is performed while reversing within a range of Lt × 0.5 or less. Thereafter, when the roll-shaped optical film is continuously produced, the above method is repeated for the movement of the T dice 1A2 or the cooling take-up portion 1B in the TD direction.

  Further, when carrying out the moving method 3 from the moving method 1, it is preferable to carry out while adjusting the film thickness in the width direction according to the result of the film thickness measuring device 1E.

  The film thickness adjustment in the width direction according to the result of the film thickness measuring apparatus 1E is performed by the following method.

  The film thickness measuring device 1E measures the film thickness in the width direction, and the film thickness in the width direction is analyzed from the measurement result to identify a location that deviates from the management standard. The position of the lip of the T die 1A2 corresponding to a location that deviates from the management standard is analyzed by the control mechanism (not shown) of the film thickness measuring device 1E from the moving distance of the T die 1A2 or the cooling take-up unit 1B and the film conveyance speed. Then, the film thickness is adjusted by correcting the lip gap (extrusion port) 1A261 (see FIG. 2) by the lip gap adjusting means 1A27 in the vicinity of the corresponding lip position.

  When producing an optical film with the film production apparatus shown in FIGS. 1 and 2, after forming a film while moving either the T die or the cooling take-up portion in the TD direction, the roll is formed at the take-up portion. The following effects were obtained by manufacturing a wound optical film.

  1. It is possible to suppress the generation of black bands due to film thickness unevenness in the TD direction, which was difficult to correct by the melt extrusion method, and to produce a stable roll-shaped optical film free from deformation and wrinkles on the film surface. became.

  2. In the winding of a thin film optical film, which is considered to have little effect by embossing, it is possible to suppress the generation of a black band, and it is possible to produce a thin roll optical film.

  3. In order to change the position of the film thickness unevenness in the TD direction by moving either the T die or the cooling take-up section during film formation, the optical axis is different from shifting the winding axis during winding to avoid overlapping of the film thickness sections. There is little risk of film breakage, and in particular, it has become possible to stably produce a thin roll optical film.

  Next, general conditions when a roll-shaped optical film is produced using the melt extrusion type film production apparatus 1 shown in FIGS. 1 and 2 will be described.

  The melting temperature of the thermoplastic resin in the melt extruder 1A1 may be appropriately selected depending on the thermoplastic resin to be used, and among these, in order to avoid deterioration of the appearance of the optical film due to thermal decomposition of the molten resin, It is preferable to maintain the temperature until discharging from the T dice at 300 ° C. or lower, and particularly preferably 290 ° C. or lower. The temperature of the melt during melt extrusion is usually in the range of 150 ° C to 300 ° C, preferably in the range of 180 ° C to 270 ° C, more preferably in the range of 200 ° C to 250 ° C. The temperature of the melt is a value measured using a contact thermometer.

  The melt extruder 1A1 has a vacuum vent for removing the volatile components because the appearance of the optical film deteriorates when the thermoplastic resin, additive, etc. used contain water or other volatile components. What was equipped with the hopper dryer etc. is used suitably.

  The cylinder diameter, L / D, compression ratio, and screw design of the melt extruder 1A1 are generally optimized in accordance with the production speed, film dimensions, and the like. What is necessary is just to optimize for the purpose of stabilizing and suppressing frictional heat generation and maintaining the resin temperature below the decomposition temperature.

  The screw rotation speed of the melt extruder 1A1 and the discharge amount from the T die 1A2 can be appropriately selected according to the thickness of the optical film to be manufactured, the take-up speed, and the like. In order to suppress thermal decomposition and yellowing due to oxidation of the molten resin, it is preferable to purge or vacuum the inside of the hopper, the extruder cylinder, etc. with an inert gas such as nitrogen or argon.

  The take-up speed of the cast roll 1B1 is preferably 5 m / min to 100 m / min in consideration of molecular orientation and birefringence.

  The temperature setting of the cast roll 1B1 is one of the important production conditions having a great influence on the appearance and characteristics of the obtained optical film, and the film-like melt flowing down from the T die 1A2 adheres to the cast roll 1B1. It is optimized in consideration of the balance between property and releasability, and is preferably set to −40 ° C. to + 20 ° C. with respect to the glass transition temperature Tg of the thermoplastic resin, and in particular, from −35 ° C. to + 10 ° C. It is preferable to do.

  In order to make the surface temperature of the touch roll 1B2 uniform, the temperature control roll may be brought into contact with the touch roll 1B2, temperature-controlled air may be sprayed, or a heat medium such as a liquid may be brought into contact.

  In the present invention, the linear pressure of the touch roll 1B2 when the touch roll 1B2 is pressed is 1 kg / cm or more and 50 kg / cm or less, and the surface temperature Tt of the film-like melt on the touch roll 1B2 side is Tg <Tt <Tg + 110. It is preferable to set it as ° C. By setting the linear pressure of the touch roll 1B2 within this range, an optical film free from bright and dark stripes and uneven spots when an image is displayed on the liquid crystal display device can be obtained.

  The linear pressure is a value obtained by dividing the force with which the pressing roll 1B2 presses the film-like melt by the width of the film-like melt at the time of pressing. The method for setting the linear pressure in the above range is not particularly limited, and for example, both ends of the elastic roll can be pressed with an air cylinder or a hydraulic cylinder. Moreover, you may press a film indirectly by pressing the press roll 1B2 with a support roll.

  In addition, as an elastic roll used as the touch roll 1B2 according to the method for producing a film of the present invention, JP-A-03-124425, JP-A-08-224772, JP-A-07-1000096, JP-A-10-272676, Use a thin-film metal sleeve-covered silicon rubber roll with a surface as described in WO97 / 028950, JP-A-11-235747, JP-A-2002-36332, JP-A-2005-172940 and JP-A-2005-280217. I can do it.

  Next, the thermoplastic resin and additives used in the present invention will be described.

(Thermoplastic resin)
The thermoplastic resin used in the method for producing an optical film of the present invention is not particularly limited as long as it can be formed by a melt casting method.

  Here, the “thermoplastic resin” refers to a resin that becomes soft when heated to the glass transition temperature or the melting point and can be molded into a desired shape.

  General thermoplastic resins include cellulose esters, polyethylene (PE), high density polyethylene, medium density polyethylene, low density polyethylene, polypropylene (PP), polyvinyl chloride (PVC), polyvinylidene chloride, polystyrene. (PS), polyvinyl acetate (PVAc), Teflon (registered trademark) (polytetrafluoroethylene, PTFE), ABS resin (acrylonitrile butadiene styrene resin), AS resin, acrylic resin (PMMA), and the like.

  When strength and resistance to breakage are particularly required, polyamide (PA), nylon, polyacetal (POM), polycarbonate (PC), modified polyphenylene ether (m-PPE, modified PPE, PPO), polybutylene terephthalate (PBT) ), Polyethylene terephthalate (PET), glass fiber reinforced polyethylene terephthalate (GF-PET), cyclic polyolefin (COP), and the like.

  When higher heat distortion temperature and long-term use characteristics are required, polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polysulfone, polyethersulfone, amorphous polyarylate, liquid crystal polymer, polyetherether Ketone, thermoplastic polyimide (PI), polyamideimide (PAI), and the like can be used. In addition, it is possible to perform the combination of the kind of resin and molecular weight according to the use of this invention.

  In the present invention, as the thermoplastic resin, it is particularly preferable to contain at least one resin selected from cellulose ester resins, acrylic resins, and cycloolefin resins.

  Hereinafter, the thermoplastic resin that can be suitably used in the present invention will be described in detail.

<Cellulose ester resin>
The cellulose ester resin that can be used in the present invention is selected from cellulose (di, tri) acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, and cellulose phthalate. Preferably, at least one kind of

  Among these, particularly preferable cellulose esters include cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate.

  As a substitution degree of the mixed fatty acid ester, when having an acyl group having 2 to 4 carbon atoms as a substituent, when the substitution degree of the acetyl group is X and the substitution degree of the propionyl group or butyryl group is Y, A cellulose resin containing a cellulose ester that simultaneously satisfies the following formulas (I) and (II) is preferable.

Formula (I) 2.0 ≦ X + Y ≦ 3.0
Formula (II) 0 ≦ X ≦ 2.5
Further, the cellulose ester used in the present invention preferably has a weight average molecular weight Mw / number average molecular weight Mn ratio of 1.5 to 5.5, particularly preferably 2.0 to 5.0, The cellulose ester is preferably 2.5 to 5.0, more preferably 3.0 to 5.0.

  The cellulose ester raw material cellulose used in the present invention may be wood pulp or cotton linter, and the wood pulp may be softwood or hardwood, but softwood is more preferred. A cotton linter is preferably used from the viewpoint of peelability during film formation. The cellulose ester made from these can be mixed suitably or can be used independently.

  For example, the ratio of cellulose ester derived from cellulose linter: cellulose ester derived from wood pulp (coniferous): cellulose ester derived from wood pulp (hardwood) is 100: 0: 0, 90: 10: 0, 85: 15: 0, 50:50: 0, 20: 80: 0, 10: 90: 0, 0: 100: 0, 0: 0: 100, 80:10:10, 85: 0: 15, 40:30:30.

  The cellulose ester resin used in the present invention has a pH of 1 g when charged in 20 ml of pure water (electric conductivity of 0.1 μS / cm or less, pH 6.8) and stirred in a nitrogen atmosphere at 25 ° C. for 1 hr. Preferably, the electrical conductivity is 6 to 7 and the electrical conductivity is 1 μS / cm to 100 μS / cm.

<acrylic resin>
Acrylic resins that can be used in the present invention also include methacrylic resins. The acrylic resin of the present invention is represented by the following general formula and preferably has a weight average molecular weight Mw of 20,000 or more and 1,000,000 or less.

General formula (1)
-(MMA) p- (X) q- (Y) r-
MMA represents methyl methacrylate, X represents a monomer unit copolymerizable with MMA having at least one amide group, and Y represents a monomer unit copolymerizable with MMA and X. p, q, and r are mol%, and are 50 <= p <= 99, 1 <= q <= 50, and p + q + r = 100.

  X is a vinyl monomer having at least one amide group copolymerizable with MMA, and X may be one type or two or more types, and one monomer unit may have a plurality of functional groups.

  Specific monomers for X include acrylamide, N-methylacrylamide, N-butylacrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide, acryloylmorpholine, N-hydroxyethylacrylamide, acryloylpyrrolidine, acryloylpiperidine, Methacrylamide, N-methylmethacrylamide, N-butylmethacrylamide, N, N-dimethylmethacrylamide, N, N-diethylmethacrylamide, methacryloylmorpholine, N-hydroxyethylmethacrylamide, methacryloylpyrrolidine, methacryloylpiperidine, N-vinyl Examples include formamide, N-vinylacetamide, and vinylpyrrolidone.

  Preferably, acryloyl morpholine and vinyl pyrrolidone are used.

  Commercially available monomers can be used as they are.

  q is 1 ≦ q ≦ 50, and is appropriately selected depending on the properties of the monomer, but preferably 5 ≦ q ≦ 30. X may be a plurality of monomers.

  Y in the acrylic resin of the present invention represents a monomer unit copolymerizable with MMA and X.

  Examples of Y include monomers such as acrylic monomers other than MMA, methacrylic monomers, olefins, acrylonitrile, styrene, and vinyl acetate. Y may be two or more.

  Y can be used as needed, and is most preferably not used.

  The weight average molecular weight (Mw) of the acrylic resin of the present invention is more preferably in the range of 20,000 to 1,000,000, particularly preferably in the range of 50,000 to 600,000, and most preferably in the range of 100,000 to 400,000. preferable.

  The weight average molecular weight of the acrylic resin of the present invention can be measured by gel permeation chromatography. The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 2,800,000-500 calibration curves with 13 samples were used. The 13 samples are preferably used at approximately equal intervals.

  As a method for producing the acrylic resin in the present invention, any known method such as suspension polymerization, emulsion polymerization, bulk polymerization, or solution polymerization may be used. Here, as a polymerization initiator, a normal peroxide type and azo type can be used, and a redox type can also be used.

  Regarding the polymerization temperature, suspension or emulsion polymerization may be performed at 30 to 100 ° C, and bulk or solution polymerization may be performed at 80 to 160 ° C. In order to control the reduced viscosity of the obtained copolymer, the polymerization can also be carried out using alkyl mercaptan or the like as a chain transfer agent.

<Cycloolefin resin>
In the present invention, it is also preferable to use a cyclo (hereinafter also referred to as “cyclic”) olefin resin. Examples of cycloolefin resins include norbornene resins, monocyclic olefin resins, cyclic conjugated diene resins, vinyl alicyclic hydrocarbon resins, and hydrides thereof. Among these, norbornene-based resins can be suitably used because of their good transparency and moldability.

  Examples of the norbornene-based resin include a ring-opening polymer of a monomer having a norbornene structure, a ring-opening copolymer of a monomer having a norbornene structure and another monomer, a hydride thereof, and a norbornene structure. An addition polymer of a monomer having a monomer, an addition copolymer of a monomer having a norbornene structure and another monomer, a hydride thereof, or the like can be given.

  Among these, a ring-opening (co) polymer hydride of a monomer having a norbornene structure is particularly suitable from the viewpoints of transparency, moldability, heat resistance, low hygroscopicity, dimensional stability, lightness, and the like. Can be used.

Examples of the monomer having a norbornene structure include bicyclo [2.2.1] hept-2-ene (common name: norbornene) and tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene. (Common name: dicyclopentadiene), 7,8-benzotricyclo [4.3.0.1 ^2,5 ] dec-3-ene (common name: methanotetrahydrofluorene), tetracyclo [4.4.0. 1 ^2,5 . ^{17, 10} ] dodec-3-ene (common name: tetracyclododecene), and derivatives of these compounds (for example, those having a substituent in the ring). Here, examples of the substituent include an alkyl group, an alkylene group, and a polar group. Moreover, these substituents may be the same or different and a plurality thereof may be bonded to the ring. Monomers having a norbornene structure can be used singly or in combination of two or more.

  Examples of the polar group include a hetero atom or an atomic group having a hetero atom. Examples of the hetero atom include an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, and a halogen atom. Specific examples of the polar group include a carboxyl group, a carbonyloxycarbonyl group, an epoxy group, a hydroxyl group, an oxy group, an ester group, a silanol group, a silyl group, an amino group, a nitrile group, and a sulfone group.

  Other monomers capable of ring-opening copolymerization with monomers having a norbornene structure include monocyclic olefins such as cyclohexene, cycloheptene, and cyclooctene and derivatives thereof, cyclic conjugated dienes such as cyclohexadiene, cycloheptadiene, and the like. And derivatives thereof.

  A ring-opening polymer of a monomer having a norbornene structure and a ring-opening copolymer of a monomer having a norbornene structure and another monomer copolymerizable with the monomer have a known ring-opening polymerization catalyst. It can be obtained by (co) polymerization in the presence.

  Examples of other monomers that can be addition copolymerized with a monomer having a norbornene structure include α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, and 1-butene, and derivatives thereof; cyclobutene, cyclopentene, Cycloolefins such as cyclohexene and derivatives thereof; non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, and the like. These monomers can be used alone or in combination of two or more. Among these, α-olefin is preferable and ethylene is more preferable.

  An addition polymer of a monomer having a norbornene structure and an addition copolymer of another monomer copolymerizable with a monomer having a norbornene structure can be used in the presence of a known addition polymerization catalyst. It can be obtained by polymerization.

  A hydrogenated product of a ring-opening polymer of a monomer having a norbornene structure, a hydrogenated product of a ring-opening copolymer of a monomer having a norbornene structure and another monomer capable of ring-opening copolymerization thereof, Hydrogenated products of addition polymers of monomers having a norbornene structure, and hydrogenated products of addition copolymers of monomers having a norbornene structure and other monomers capable of addition copolymerization with these A known hydrogenation catalyst containing a transition metal such as nickel or palladium is added to the polymer solution, and the carbon-carbon unsaturated bond is preferably hydrogenated by 90% or more.

Among norbornene-based resins, as repeating units, X: bicyclo [3.3.0] octane-2,4-diyl-ethylene structure and Y: tricyclo [4.3.0.1 ^2,5 ] decane-7 , 9-diyl-ethylene structure, the content of these repeating units is 90% by mass or more based on the entire repeating units of the norbornene resin, and the content ratio of X and the content ratio of Y The ratio of X: Y is preferably 100: 0 to 40:60. By using such a resin, it is possible to obtain a light confinement film having no dimensional change over a long period of time and excellent optical property stability.

  The molecular weight of the cyclic olefin resin used in the present invention 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 is not dissolved) as a solvent, usually 20,000 to 150,000. . Preferably it is 25,000 to 100,000, more preferably 30,000 to 80,000. When the weight average molecular weight is in such a range, the mechanical strength and molding processability of the film are highly balanced and suitable.

  The glass transition temperature of the cyclic olefin resin may be appropriately selected according to the purpose of use. From the viewpoint of durability and stretch processability, it is preferably in the range of 130 ° C to 160 ° C, more preferably 135 ° C to 150 ° C.

  The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the cyclic olefin resin is 1.2 to 3.5, preferably 1.5 to 3.0, from the viewpoint of relaxation time, productivity and the like. More preferably, it is 1.8 to 2.7.

The cyclic olefin resin used in the present invention preferably has an absolute value of photoelastic coefficient of 10 × 10 ⁻¹² Pa ⁻¹ or less, more preferably 7 × 10 ⁻¹² Pa ⁻¹ or less, and more preferably 4 × 10. It is particularly preferably ⁻¹² Pa ⁻¹ or less. The photoelastic coefficient C is a value represented by C = Δn / σ where birefringence is Δn and stress is σ.

  In the present invention, it is preferable that the cyclic olefin resin does not substantially contain particles. Here, “substantially free of particles” means that even if particles are added to a film made of a cyclic olefin resin, the amount of increase in haze from the non-added state is allowed to be in the range of 0.05% or less. It means you can do it. In particular, the alicyclic polyolefin resin lacks affinity with many organic particles and inorganic particles. Therefore, when a cyclic olefin resin film to which particles exceeding the above range are added is stretched, voids are easily generated, and as a result, There is a risk that a significant decrease in haze occurs.

(Additive)
Examples of the additive relating to the method for producing a roll film of the present invention include an ester plasticizer having a structure in which an organic acid and a trivalent or higher alcohol are condensed, and an ester plasticizer comprising a polyhydric alcohol and a monovalent carboxylic acid. , At least one plasticizer of an ester plasticizer comprising a polycarboxylic acid and a monohydric alcohol, a phenolic antioxidant, a hindered amine light stabilizer, a phosphorus stabilizer, or a sulfur stabilizer. It is preferable to contain a stabilizer, and in addition to this, a peroxide decomposing agent, a radical scavenger, a metal deactivator, an ultraviolet absorber, a matting agent, a dye, a pigment, and other plasticizers and hinders. You may include antioxidants other than a dophenol antioxidant.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1
(Preparation of pellets)
The following composition was mixed for 60 seconds at 2300 r / min using a Henschel mixer. Subsequently, in a twin-screw extruder with a vent and L / D = 35 (ratio of the effective length L of the screw of the extruder to the radius D), the diameter is 250 ° C. through a strand die while sucking vacuum with a vent. Extruded in a 3 mm strand shape, washed with 50 ° C. water for 1 minute, drained, and then cut from 2 mm to 3 mm in length to produce pellets.

(Composition)
Cellulose acetate propionate (manufactured by Eastman Chemical Co., Ltd., trade name: CAP-482-20) 35 parts by mass acrylic copolymer (MMA / ACMO *: 70/30, average molecular weight 100,000)
65 parts by mass Stabilizer IRGANOX1010 (manufactured by BASF Japan) 0.5 parts by mass Stabilizer PEP-36 (manufactured by ADEKA) 0.075 parts by mass Stabilizer Sumilizer (GS: manufactured by Sumitomo Chemical Co., Ltd.) 0 .48 parts by mass ACMO *: acryloylmorpholine (drying of pellets)
The produced pellets were dried with a hot air dryer at 90 ° C. until the water content became 500 ppm or less.

(Manufacture of optical film (sample No. 101 to 130))
Using the manufacturing apparatus shown in FIG. 1, the prepared pellets were formed by moving the T die in the melt extrusion part or moving the cooling take-up part in the TD direction under the conditions shown in Table 1, and then stretching the MD in the stretching part. And TD stretching, both ends were cut with a slitter so that the width of the optical film after TD stretching was 2200 mm, embossed with a height of 4 μm on both sides, and a winding core with a winding of 8000 m. A roll-shaped optical film having a film thickness of 20 μm was manufactured continuously while changing the winding core. 101 to 130. In addition, before performing MD extending | stretching, both ends were excised with a slitter so that it might become 1300 mm. Moreover, before performing TD extending | stretching, both ends were excised with a slitter so that it might become 1150 mm.

(Production of Comparative Optical Film (Comparative Sample No. 131))
A roll-shaped optical film was produced under the same conditions except that the positions of the T dice and the cooling take-up portion were fixed. 131.

(Production of Comparative Optical Film (Comparative Sample No. 132))
In addition, the position of the T dice and the cast roll is fixed, and the winding shaft is moved back and forth in the TD direction in the TD direction by 10 reciprocations at 25 mm width (± 12.5 mm) every 8 minutes. A roll-shaped optical film was manufactured under the conditions, and comparative sample No. 132.

(Melt extrusion conditions of the melt extrusion part)
Single screw extruder: screw diameter 90 mm, L / D = 30 (ratio of effective length L of screw of extruder and radius D)
Melting temperature: 250 ° C
Extrusion environment: Nitrogen gas was sealed from the vicinity of the material supply port, and the inside of the extruder was kept in a nitrogen atmosphere.

  T dice: Coat hanger type with a width of 1500 mm, the inner wall is hard chrome plated and finished to a mirror surface with a surface roughness of 0.1S. For adjustment of the lip gap, lip gap adjustment bolts were provided at 60 intervals at a gap of 25 mm, with a gap of 25 mm (distance from the center of the adjustment bolt to the center). The average film thickness of the film-forming film was adjusted to 80 μm, and the film thickness fluctuation range was adjusted to ± 2 μm.

T-die lip gap: 1mm
Extrusion amount of melt from T-die: 200 kg / hr
(Cooling take-up part)
Take-up speed: 50 m / min until entering the MD stretching apparatus
(Preparation of cast roll)
Cast roll diameter: 400mm
Cast roll surface temperature: 120 ° C
The surface temperature of the cast roll was controlled by flowing cooling water.

(Preparation of touch roll)
An elastic touch roll comprising a metal outer cylinder and a metal inner cylinder was prepared as a touch roll.

Surface temperature: 90 ° C
As the surface temperature of the elastic touch roll, oil was used as a heat medium in the gap.

Elastic touch roll pressing (linear pressure): 20 N / mm
(Extension part)
MD stretching apparatus: having 6 heat rolls, gradually increasing the conveyance speed to 100 m / min with the temperature adjusted to 60 ° C, 90 ° C, 120 ° C, 120 ° C, 90, 60 ° C in order from the entrance The stretching ratio was 2.0 times.

TD stretching device: clip type tenter TD stretching ratio: 2.0 times (winding part)
Winding speed: 100 m / min
Tension at the time of winding: The winding tension at the start of winding was 200 N, and thereafter the winding tension was decreased by 5% per 1000 m to wind up with a length of 8000 m.

  TD direction maximum travel (Tmax) distance of T dice *: Indicates the distance traveled in the time (80 minutes) for producing one roll of optical film with reference to the center in the width direction of the T dice.

  TD direction maximum movement (Tmax) distance * of the cooling take-up part: Indicates the distance moved in the time (80 minutes) for producing one roll of optical film with reference to the center in the width direction of the cast roll.

Movement method 1 *:
When continuously manufacturing a roll-shaped optical film, when the time for manufacturing one roll-shaped optical film is Lt (80 minutes), T dice 1A2 (see FIG. 2) or cooling take-up section 1B ( The movement in the TD direction of FIG. 2) is moved in the same direction in the range of 17 mm to 25 mm during Lt (80 minutes), and when the next roll-shaped optical film is manufactured, the T dice 1A2 (FIG. 2) Reference) or cooling take-up portion 1B (see FIG. 2) is moved in the TD direction in the opposite direction to that in the previous roll-shaped optical film. Thereafter, when the roll-shaped optical film is continuously produced, the movement in the TD direction of either the T dice 1A2 (see FIG. 2) or the cooling take-up unit 1B (see FIG. 2) is alternately performed.

Movement method 2 *
When continuously manufacturing a roll-shaped optical film, when the time for manufacturing one roll-shaped optical film is Lt (80 minutes), T dice 1A2 (see FIG. 2) or cooling take-up section 1B ( When one of the movements in the TD direction of FIG. 2) is moved in the same direction in the range of 17 mm to 25 mm during Lt (80 minutes), and the next roll-shaped optical film is manufactured, the T die 1A2 (see FIG. 2) or cooling take-up section 1B (see FIG. 2) is returned to the position when the immediately preceding roll-shaped optical film was manufactured, and in the same direction as when the immediately preceding roll-shaped optical film was manufactured. The part wound up in the time until it is moved and the T dice 1A2 (see FIG. 2) or the cooling take-up part 1B (see FIG. 2) is returned to the position at the time when the roll-shaped optical film is manufactured immediately before is discarded. Thereafter, when the roll-shaped optical film is continuously produced, the above method is repeated for the movement of the T dice 1A2 (see FIG. 2) or the cooling take-up portion 1B (see FIG. 2) in the TD direction.

Movement method 3 *
When continuously manufacturing a roll-shaped optical film, when the time for manufacturing one roll-shaped optical film is Lt (80 minutes), T dice 1A2 (see FIG. 2) or cooling take-up section 1B ( Any one of the movements in the TD direction in FIG. 2) is performed while inverting at a cycle of Lt (80 minutes) × 0.5 or less in the range of 17 mm to 25 mm during Lt (80 minutes). Thereafter, when the roll-shaped optical film is continuously produced, the above method is repeated for the movement of the T dice 1A2 (see FIG. 2) or the cooling take-up portion 1B (see FIG. 2) in the TD direction.

Evaluation Each sample No. A sample prepared on a roll-shaped optical film of Nos. 101 to 132, 1 roll, 5 rolls, and 8 rolls was left in an environment at a temperature of 25 ° C. and a humidity of 50% RH for 1 week, and then a black band, a rolled form, and a tight clamp And evaluated by the following method. The results are shown in Table 2.

(Black band evaluation method)
The peripheral surface was visually observed.

(Evaluation rank of black band)
○: Black band is not visible △: Black band is faintly observed ×: Black band is clearly visible (Evaluation method for rolled shape)
The peripheral surface was visually observed.

Evaluation rank for rolled shape ○: No wrinkles or creases, smooth surface △: Slight wrinkles on the surface ×: Clear wrinkles on the surface (Evaluation method for tightening)
The peripheral surface was touched and evaluated.

(Rating tightening evaluation rank)
○: Same tightness for the entire width △: Some variation in hardness, but no tightly tightened part ×: Some parts are clearly tightly tightened

  A melt extrusion section for extruding a melt containing at least a thermoplastic resin and an additive as a film-like melt from a T die having a plurality of lip gap adjusting means; and a cooling take-up section having at least a touch roll and a cast roll When manufacturing an optical film by a melt extrusion type film manufacturing apparatus having a winding part, sample No. 1 manufactured while moving either the T die or the cooling take-up part in the TD direction. It was confirmed that all of 101 to 130 had no black band, the winding shape was stable, and the winding was stable without tightening.

  Sample No. 131 prepared by the conventional method in which both the T-die and the cooling take-up portion are fixed is attached to all of the generation, winding shape, and tightening of the black band. Results were inferior to 101-130.

  Sample No. prepared by shifting the winding shaft in the TD direction during winding. No black band was observed for No. 132, but breakage occurred midway. In addition, the sample No. of the present invention is attached to the winding shape and tightening. Results were inferior to 101-130. The effectiveness of the present invention was confirmed.

DESCRIPTION OF SYMBOLS 1 Film manufacturing apparatus 1A Melt extrusion part 1A1 Melt extrusion machine 1A2 T die 1A261 Lip gap (extrusion port)
1A27 Lip gap adjusting means 1B Cooling take-up part 1B1 Cast roll 1B2 Touch roll 1B3, 1B4 Auxiliary cooling roll 1B5 Peeling roll 1C Stretching part 1C1 MD stretching part 1C11 MD stretching apparatus 1C2 TD stretching part 1C21 TD stretching part 1E Winding part 1E Thickness measuring device 1F Slitter 2 Film 2a Unstretched film 2b, 2c Stretched film

Claims (9)

A melt extrusion section for extruding a melt containing at least a thermoplastic resin and an additive as a film-like melt from a T die having a plurality of lip gap adjusting means; and a cooling take-up section having at least a touch roll and a cast roll In the manufacturing apparatus of the melt extrusion type optical film having a winding part,
An apparatus for producing an optical film, wherein either one of the T dice or the cooling take-up part is formed while moving in the TD direction, and then wound into a roll shape by the take-up part. A melt extrusion section for extruding a melt containing at least a thermoplastic resin and an additive as a film-like melt from a T die having a plurality of lip gap adjusting means; and a cooling take-up section having at least a touch roll and a cast roll In an optical film manufacturing method for manufacturing an optical film by a melt extrusion type film manufacturing apparatus having a winding part,
An optical film manufactured by forming one of the T die and the cooling take-up part while moving in the TD direction, and then producing a roll-up optical film at the take-up part. Production method. When the maximum value of the movement width T in the TD direction of the cooling take-up section or the T die is Tmax and the interval between the plurality of lip gap adjusting means is R, the following relationship is obtained. The method for producing an optical film according to claim 2.
0.75R <Tmax   When the optical film is wound up by the winding unit and a plurality of roll-shaped optical films are continuously manufactured, when the time for manufacturing one roll-shaped optical film is Lt, the T dice, or The movement of the cooling take-up unit in the TD direction is moved in the same direction during the Lt, and when the next roll-shaped optical film is manufactured, the T dice or the cooling take-up unit The method for producing an optical film according to claim 2 or 3, wherein the movement in the TD direction is set in a direction opposite to that in the previous roll-shaped optical film.   When the optical film is wound up at the winding section and a plurality of roll-shaped optical films are continuously manufactured, when the time for manufacturing one roll-shaped optical film is Lt, the T dice or the When the next roll-shaped optical film is manufactured by moving the movement in the TD direction of any one of the cooling take-up portions in the same direction during the Lt, the T dice or the cooling take-up The part is returned to the position where the previous roll-shaped optical film was manufactured, moved in the same direction as when the previous roll-shaped optical film was manufactured, and returned to the position where the previous roll-shaped optical film was manufactured. The method for producing an optical film according to claim 2, wherein the winding portion of the time up to is discarded.   When the optical film is wound up by the winding unit and a plurality of roll-shaped optical films are continuously manufactured, when a time for manufacturing one roll-shaped optical film is Lt, T dice or cooling drawing is performed. The movement of any one of the take-up portions in the TD direction is reversed during the Lt, and the movement of the T dice or the cooling take-up portion in the TD direction is reversed at a cycle of Lt × 0.5 or less. The method for producing an optical film according to claim 2 or 3.   The method for producing an optical film according to claim 2, wherein both ends of the film are cut off at fixed positions after passing through the cooling take-up portion.   7. The film manufacturing apparatus includes a film thickness measuring device for the optical film, and the lip gap is adjusted by the lip gap adjusting means according to a measurement result of the film thickness measuring apparatus. The manufacturing method of the optical film of Claim 1.   The film thickness of the optical film when wound by the winding unit is 10 μm or more and 25 μm or less, and the length of the optical film wound in the roll shape is 4000 m or more and 35000 m or less. The method for producing an optical film according to any one of claims 2 to 6.

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