KR20160030843A - Method of producing film and apparatus of stretching film - Google Patents

Abstract

Provided are a film manufacturing method and a film stretching apparatus, which make less effects on the waveform deformation of a film after being stretched in the horizontal direction, and do not cause cutting defects. A long film (12) is manufactured into a thickness of 40 μm or less by being stretched in the width direction while being transferred. In a stretching step, both side portions of the film (12) are gripped by a clip (50) to be stretched in the width direction. In a cutting step, the both side portions of the film (12), which are gripped by the clip (50), are cut by a cutting blade (75). In a pass roller transfer step, the film (12) whose both side portions, gripped in the stretching step, are opened is wound around a second pass roller (72) and a third pass roller (73) and then transferred. The total angle of the film (12) wound around the second pass roller (72) and the third pass roller (73) is 90° or greater. The waveform deformation of the film (12) is lessened by the second pass roller (72) and the third pass roller (73), thereby suppressing cutting defects.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing a film,

The present invention relates to a film production method for producing a film and a film stretching apparatus.

The strip-shaped thermoplastic resin film is stretched in the carrying direction (longitudinal direction) or the width direction (transverse direction) to form a thin film having a desired thickness. In addition, in-plane retardation (Re) and thickness direction retardation (Rth) can be expressed by stretching. Due to such properties, the thermoplastic resin film is used for optical applications such as a retardation film of a liquid crystal display device, for example.

In the case of producing a thin film by stretching in the transverse direction (hereinafter referred to as transverse stretching), for example, in JP-A-2013-63569, in order to cut off the grip marks by the clip at the time of stretching, Both sides of the film are cut off from the film product part by a tool.

Further, after the transverse stretching, as shown in, for example, Japanese Patent Laid-Open Publication No. 2010-162740, there is a problem that the film is broken at the time of winding by the wrinkles (wrinkles) May occur. For this reason, in the film production method described in Japanese Patent Application Laid-Open No. 2010-162740, wrinkles and elongation in the width direction, which occur in a long length in the carrying direction, are eliminated by using an expander roll or a multi-tension roll.

However, recent liquid crystal display devices are required to be lightweight, thin, and high in quality, and are required to be thin and of high quality, for example, about 40 占 퐉 or less. When such a thin film is produced by a conventional stretching machine, surface irregularities of a long corrugated shape in the conveying direction may occur on the side of the film. Such wave deformation becomes more problematic when it is subjected to subsequent film drying, film winding, and the like. In addition, when the film is cut by the slitter and both side portions are cut out from the main body portion, for example, from the above-mentioned film product portion, there is a case where cutting defects occur due to the influence of wave deformation.

In the case of using an expander roll or a multi-tension roll, as shown in Japanese Laid-Open Patent Publication No. 2010-162740 (specification paragraph 0015), even if the tension is partially changed in the width direction of the film, There is no problem. Since the expander roll or the multi-tension roll described above acts a tension in the width direction, scratches caused by sliding the film in the width direction on an expander roll or a multi-tension roll, or a roll having a different diameter in the width direction There is a fear of scratches due to the difference in speed of the main body caused by the difference.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a film production method and a film stretching apparatus in which the effect of corrugation is reduced and cutting defects do not occur at the time of cutting the both side portions successively after the thin film is transversely stretched .

A film production method of the present invention comprises a stretching step (A step), a cutting step (B step), and a path roller conveying step (C step), stretching in the width direction while conveying a long thermoplastic resin film Is 40 탆 or less. In the step A, both side portions of the thermoplastic resin film are gripped by the grip portions and stretched in the width direction. In the step B, both side portions held by the grip portion of the thermoplastic resin film are cut off by the cutting edge. Step C is a step of winding a thermoplastic resin film on both sides of the thermoplastic resin film, which has been released in the step A, over two or more path rollers arranged in the transport direction, and transports the thermoplastic resin film to a cutting edge. The total wrapping angle with respect to the path roller is 90 DEG or more.

In the step A, it is preferable to widen the width of the thermoplastic resin film to 1.07 times or more.

The transport path length of the thermoplastic resin film from the gripping opening position of the thermoplastic resin film by the grip portion to the cutting edge is preferably 1.0 m or more.

It is preferable that the grip portion is a clip holding both side portions of the thermoplastic resin film.

The thermoplastic resin film is preferably a cellulose acylate film.

The film stretching apparatus of the present invention includes a tenter, a cutting edge, and two or more pass rollers, and stretches in the width direction while conveying a long thermoplastic resin film to produce a film having a thickness of 40 m or less. The tenter grasps both side portions of the thermoplastic resin film by the grip portion and stretches in the width direction. The cutting edge cuts both side portions gripped by the grip portion of the thermoplastic resin film. The two or more path rollers are disposed apart from the gripping opening position of both side portions by the gripping portion to the cutting edge. The total winding angle of the thermoplastic resin film in the two or more pass rollers is 90 DEG or more.

It is preferable that the tenter widen the width of the thermoplastic resin film to 1.07 times or more.

According to the present invention, the influence of the waveform deformation of the thermoplastic resin film after transverse stretching is suppressed, and the occurrence of cutting defects is eliminated.

The above objects and advantages will be readily apparent to those skilled in the art by reading the detailed description of the preferred embodiments with reference to the accompanying drawings.
1 is a side view showing an outline of an example of a solution film-forming equipment.
2 is a plan view showing an outline of a film stretching device.
3 is a side view showing the outline of the chamber and the duct of the tenter.

The resin in the film produced by the present invention is a transparent thermoplastic resin (polymer). In the present embodiment, cellulose acylate is used as the thermoplastic resin.

Among the cellulose acylates, the present invention is particularly effective when TAC (cellulose triacetate) in which the substitution degree of an acyl group with respect to a hydroxyl group of cellulose satisfies the following formulas (1) to (3) is used. In the formulas (1) to (3), A and B represent substitution degree of an acyl group with respect to a hydrogen atom in the hydroxyl group of cellulose, A represents substitution degree of an acetyl group, and B represents an acetyl group It is a degree of substitution of practical use. The total acyl group substitution degree Z of the cellulose acylate is a value obtained by A + B.

(1) 2.7? A + B? 3.0

(2) 0? A? 3.0

(3) 0? B? 2.9

The present invention is particularly effective also in the case of using DAC (cellulose diacetate) in which the substitution degree of an acyl group with respect to the hydroxyl group of cellulose is satisfying the following formula (4) instead of TAC.

(4) 2.0? A + B? 2.7

From the viewpoint of the wavelength dispersion of the retardation, the sum B of the substitution degree A of the acetyl group of the DAC and the substitution degree of the acyl group having 3 to 22 carbon atoms, satisfying the formula (4), can be represented by the following formulas 6).

(5) 1.0 < A < 2.7

(6) 0 < B < 1.5

The glucose unit having? -1,4 bonding constituting cellulose has a hydroxyl group (hydroxyl group) liberated at 2-position, 3-position and 6-position. The cellulose acylate is a polymer (polymer) obtained by esterifying a part or all of these hydroxyl groups with an acyl group having 2 or more carbon atoms. The degree of acyl substitution means the ratio of esterification of the hydroxyl group of cellulose to the 2-position, 3-position and 6-position, respectively (100% esterification is referred to as substitution 1).

1 is for producing a long cellulose acylate film (hereinafter simply referred to as " film ") 12 from the dope 11. The solution deposition apparatus 10 shown in Fig. The dope 11 is a polymer dissolved in a solvent. The solution film-forming equipment 10 includes a film stretching device 17 composed of a flexible device 14, a tenter 15 and a slitter device 16, a drying chamber 18, (19) and a winding device (20) are provided in this order from the upstream side.

The flexible device 14 is for forming a film 12 containing a solvent from the dope 11. [ The flexible device 14 is provided in a chamber 36 for partitioning the belt 30, the flexible die 31, the backup roller 33 and the peeling roller 35 from the external space. The flexible die 31 flows out the dope 11 toward the belt 30. [ The belt 30 is an endless flexible support formed in an annular shape and spans a pair of backup rollers 33. [

At least one of the pair of backup rollers 33 has a driving portion (not shown), and the driving portion rotates about the shaft 33a. By this rotation, the belt 30, which is wrapped around the peripheral surface, is transported in the longitudinal direction. The dope 11 flows out from the flexible die 31 toward the circumferential surface of the conveyed belt 30 so that the dope 11 becomes flexible on the peripheral surface of the belt 30 to form the flexible film 32. [ Between the flexible die 31 and the belt 30, a bead made of the dope 11 is formed. A chamber (not shown) is provided upstream of the bead in the rotating direction of the backup roller 33 to depressurize the upstream area of the bead by sucking air.

The temperature of the circumferential surface of each backup roller 33 is controlled by the warmer 33b. A flow path through which the heat transfer medium flows is formed in the back-up roller 33. The temperature controller 33b regulates the temperature of the heat transfer medium and circulates the heat transfer medium with the backup roller 33. [ By adjusting the circumferential surface temperature of the backup roller 33, the temperature of the flexible film 32 is controlled via the belt 30. For example, in the so-called cooling mode in which the flexible film 32 is cooled and solidified (gelled), the warmer 33b cools the heat transfer medium and sends the cooled heat transfer medium to the backup roller 33. [ By carrying out this conveyance successively for example, the heat transfer medium circulates in the flow path inside the backup roller 33 and returns to the warmer 33b. In the case of so-called drying softening in which the flexible film 32 is dried and solidified, the warming-up operation 33b heats the backup roller 33, for example.

Further, the flexible support is not limited to the belt 30. For example, instead of the belt 30, a drum (not shown) rotating in the circumferential direction may be used as the flexible support. In the case of dry embossing, the belt 30 is often used, and in the case of cooling embossing, a drum is often used. When the drum is used as a flexible support, the temperature of the circumferential surface of the drum is adjusted by passing the heat transfer medium through the inside of the drum, and the temperature of the flexible film 32 is controlled through the drum.

The peeling roller 35 is for keeping the peeling position where the flexible film 32 is peeled off from the belt 30 constant and is arranged so that the axial direction is parallel to the axial direction of the backup roller 33. [ The flexible film 32 is peeled from the belt 30 at a predetermined position by pulling the film 12 in the carrying direction Z1 and supporting the film 12 on the peripheral surface of the peeling roller 35. [ By this continuous peeling, the film 12 is formed long.

A condenser (condenser) for vaporizing the solvent vaporized from each of the dope 11, the flexible film 32 and the film 12 is provided in the flexible apparatus 14. The solvent liquefied by the condenser is guided to a recovery device disposed outside the chamber 36, and recovered in the recovery device. The illustration of the condenser and the recovery device is omitted.

The film 12 is guided by the roller 40 from the flexible device 14 to the tenter 15 of the film stretching device 17. [ The tenter 15 is a so-called clip tenter holding the respective side portions 12b (see Fig. 2) of the film 12 by holding (grasping) by a plurality of clips (grip portions) And travels in a predetermined orbit. The film 12 is transported by traveling of the clip 50.

2, the tenter 15 has a chamber 43 surrounding the conveying path of the film 12 and partitioning the conveying path and the periphery thereof from the external space. In the following description, the term "transport path" simply means a transport path for the film 12. The chamber 43 is divided into a preheating area 45, a stretching area 46 and a cooling area 47 in this order from the upstream side in the carrying direction Z1 and temperature controlled dry air is sent to each area .

The tenter 15 is provided with a clip 50, rails 51 and 52, chains 53 and 54, a duct as an air outflow section (see FIG. 3) 55, and an air supply section 56 do. The clip 50 holds the side portion 12b of the film 12. The rails 51 and 52 guide the running of the clip 50 and are provided on both sides of the conveying path of the film 12. [ The air supply unit 56 sends dry air of a predetermined condition to the duct 55. The duct 55 discharges dry air to dry the film 12.

The plurality of clips 50 are attached to the chains 53, 54 at predetermined intervals. The chains 53 and 54 are mounted on the rail 51 and the rail 52 so that they can freely move along the rails 51 and 52. The chains 53 and 54 are engaged with a turn wheel 57 disposed on the upstream side of the preheating area 45 and a sprocket 58 disposed on the downstream end of the cooling area 47. [ As the sprocket 58 rotates, the chains 53 and 54 run continuously. By the running of the chains 53 and 54, the clip 50 moves along the rails 51 and 52.

On the upstream side of the preheating area 45, a gripping start member 64 for starting gripping of the side portion 12b of the film 12 is formed on the clip 50. A grip releasing member 65 for releasing gripping of the side portion 12b of the film 12 is formed on the clip 50 on the downstream side of the cooling area 47. [ The film 12 is gripped by the clip 50 at the gripping start position PA on the upstream side of the preheating area 45 and the clip 50 moves along the rails 51 and 52 in the longitudinal direction And is sequentially passed through the preheating area 45, the stretching area 46, and the cooling area 47. The film 12 is subjected to a predetermined process in the preheating to cooling areas 45 to 47 while passing through the preheating to cooling areas 45 to 47 and the gripping open position at the downstream side of the cooling area 47 The gripping by the clip 50 is released.

The rail 51 and the rail 52 are separated from each other by a predetermined rail width. The rail width can be adjusted by a rail moving mechanism (not shown), and the drawing magnification can be changed by changing the rail width. The rail width is constant in the preheating area 45 as the width W1. Thus, in the preheating area 45, the film 12 is transported while maintaining a constant width in a regulated width.

The stretching area 46 is for performing the stretching process (stretching step), and the width of the rail gradually increases in the carrying direction Z1, that is, toward the downstream side. As a result, in the stretching area 46, the film 12 is stretched (transversely stretched) in the width direction Z2 while being conveyed, thereby widening the width. Concretely, when the width of the film 12 to be introduced into the stretching area 46 is W1 and the width of the film 12 exiting the stretching area 46 is W2, By this adjustment, the draw ratio obtained by W2 / W1 is 1.01 times or more and 5.0 times or less, for example.

The cooling area 47 is for performing the cooling process (cooling step), and the rail width is constant. As a result, in the cooling area 47, the film 12 is transported with the width kept constant at W2. The above-mentioned " constant " regarding the rail width in the preheating area 45 and the cooling area 47 need not be strictly defined, but the width W1 and the width W2, (For example, a change within 2%) of the rail width.

3, the duct 55 is formed above the conveying path so that the distance between the duct 55 and the conveying path of the film 12 becomes substantially constant. A slit-shaped blowout opening 61 extending in the width direction Z2 of the film 12 is formed in the lower portion of the duct 55. The blowout opening 61 is formed in a plurality of . A duct having the same configuration as that of the duct 55 is formed below the conveying path of the film 12 so that the distance from the conveying path is substantially constant. In the duct (not shown) below the conveying path, the respective blow-out openings are formed in the upper part. Further, the carrying direction Z1 and the width direction Z2 are orthogonal.

The inside of the duct 55 is partitioned into, for example, first to third feed chambers 55a to 55c by a plurality of partition plates 62. [ In the present embodiment, as shown in Fig. 3, a plurality of air outlets 61 for the first to third air supply chambers 55a to 55c are respectively provided. Specifically, the number of outlets 61 of the first air supply chamber 55a is two, the number of air outlets 61 of the second air supply chamber 55b and the number of air outlets 61 of the third air supply chamber 55C are three, The number of air outlets 61 in each of the third-class air chambers 55a to 55c is not limited to this. Although not shown in the drawing, an exhaust hole, an exhaust groove, or the like may be formed between each of the blow-out openings 61.

The air supply part 56 supplies dry air to the first to third air supply rooms 55a to 55c of the duct 55. [ The air supply unit 56 is equipped with a warming unit (not shown) that independently controls the temperatures of the respective drying air supplied to the first to third air supply rooms 55a to 55c. The dry air adjusted to a predetermined temperature is supplied to the preheating area 45, the elongating area 46 and the cooling area 47 via the first to third feeder chambers 55a to 55c, do. The temperature in the first to third feeder chambers 55a to 55c may be constant or the temperature region may be further subdivided in the transport direction Z1 of the film 12.

The film 12 is heated in advance before entering the stretching area 46 by the supply of the drying air from the first air chamber 55a. The stretching in the stretching area 46 is started promptly by the heating by the preheating area 45 and the film 12 is stretched more uniformly in the width direction Z2 One tension is given.

In the stretching step of the tenter 15, it is preferable to stretch the film 12 in the width direction Z2 while maintaining the temperature of the film 12 at, for example, 140 占 폚 or less. The draw ratio can be arbitrarily set within the range of 1.01 times to 5.0 times. In the present embodiment, the draw ratio is 1.07 times or more and 5.0 times or less, preferably 1.07 times or more and 2.00 times or less.

While passing through the tenter 15, the film 12 is dried. In the tenter 15, the drying of the film 12 is preferably performed so that the residual solvent amount of the film 12 is, for example, within a range of 3 mass% to 20 mass%. The amount of the residual solvent in the present specification means the amount of residual solvent when the mass of the film 12 to be measured is X and the mass after the film 12 is completely dried is Y, ) / Y} x 100, which is a so-called dry weight reference value. Also, the " completely dried " amount of solvent need not strictly be 0 (zero). For example, the mass after the film 12 to be measured is subjected to the drying treatment may be Y for 3 hours at 140 占 폚.

The slitter 16 disposed downstream of the tenter 15 includes a first pass roller 71 to a fourth pass roller 74 and a cutting edge 75 to perform cutting (cutting step) . The first path roller 71 to the fourth path roller 74 are disposed apart from the upstream side in the transport direction Z1 toward the downstream side and the first path roller 71 to the fourth path roller 74 74 to transport the film 12 (pass roller conveying step). The first path roller 71 to the third path roller 73 are disposed upstream of the cutting edge 75 and the fourth path roller 74 is disposed downstream of the cutting edge 75.

The film 12 is wound around at least two of the first pass rollers 71 to the third pass rollers 73 disposed upstream of the cutting edge 75 so that the total wrapping angle becomes 90 degrees or more. The total wrapping angle is the sum of the wrapping angles (wrap angle) in each of the plurality of pass rollers disposed upstream of the cutting edge 75. In this example, the first pass rollers 71 to the third pass (Wrap angle) in each of the rollers 73. [0060] That is, the winding angle of the first path roller 71 is? 71, the winding angle of the second path roller 72 is? 72, and the winding angle of the third path roller 73 is? The total wrapping angle is obtained by an equation of? 71 +? 72 +? 73. Further, the winding angle is a central angle of the fan-shaped portion formed from the center of the wrapping area and the circular section in the circumferential surface of the film 12 when the roll 12 is wound around, as viewed from the side, as shown in Fig.

In the present embodiment, the first path roller 71 supports the film 12 coming out of the tenter 15 from below. Thus, the first path roller 71 is formed so as to keep the transport path horizontally, and the direction of the transport path upstream and downstream of the first path roller 71 is the same. That is, the winding angle? 71 of the film 12 in the first path roller 71 is 0 °. In this case, however, the film 12 may be wound around the first path roller 71 so that the upstream end of the first path roller 71 and the downstream end of the first path roller 71 And the direction of the downstream conveying path is made different from each other. That is, when the direction of the conveying path is changed in this manner, the winding angle? 71 of the film 12 with respect to the first path roller 71 is made larger than 0 degrees. Even when the first path roller 71 is formed so as to keep the transport path horizontally, the contact with the first path roller 71 is not linear due to the influence of the weight of the film 12, And the film 12 is wound around the first path roller 71. In this way, in order to keep the transport path horizontally, the film 12 against the path roller when supporting the film 12 from below, Is considered to be 0 deg.

The film 12 is wound around the second path roller 72 and the third path roller 73 and the winding angle? 72 and the winding angle? 73 are larger than 0 °. The second path roller 72 and the third path roller 73 are arranged so that the total winding angle is 90 DEG or more in this example because the winding angle? (Wrap angle) of the film 12 becomes 90 degrees or more, whereby the shape of the transport path (path) as viewed from the side of the film 12 is folded back into the Z-shape. In short, in the present embodiment, the total wrapping angle is the sum of the wrapping angles of the film 12 wound around the second pass roller 72 and the third pass roller 73. When the film 12 is also wound on the first pass roller 71, the angle? 71 is also calculated as the total wrapping angle. In addition, the Z-shape includes an original Z-shape in which the folded back portion has an acute angle (less than 90 占), and an approximately Z-shape having an obtuse angle (90 占 or more and 180 占 or less).

In the present embodiment, the path rollers disposed upstream of the cutting edge 75 are the first path roller 71 to the third path roller 73, but the number is not limited to this. When the number is 2, the film 12 is wound around both of the two pass rollers, and the angle of total wrapping is made 90 degrees or more. When the number of the pass rollers is 4 or more, the film 12 is wound around at least two pass rollers to set the total wrapping angle to 90 degrees or more. Thus, the number of pass rollers to be subjected to the total wrapping angle is three Or more.

The second path roller 72 is disposed on the release surface side of the film 12 peeled from the belt 30 so that the shape of the conveying path (path) 73 are disposed on the semi-peeled surface side opposite to the peeling surface. As described above, it is more preferable that the pass rollers around which the film 12 is wound are arranged in a zigzag manner with respect to the conveying path.

A cutting edge 75 is disposed between the third path roller 73 and the fourth path roller 74. The cutting blade 75 is a laser blade or a collapsible blade or the like and successively cuts each side portion 12b of the film 12 in the carrying direction Z1. This cuts the film 12 that cuts the respective side portions 12b from the central portion 12a of the product 12 of the film 12 (cutting step), and carries out the cutting by the clip 50 in the tenter 15 The trace is removed.

The length L1 of the conveying path of the film 12 from the gripping open position PB of the tenter 15 to the cutting edge 75 (hereinafter referred to as the conveying path length) L1 is 1.0 m or more. The conveying path length L1 is a length in the case where there is a first path roller 71 to a third path roller 73 in between. The conveying path length L1 shown in Fig. 2 is the same as the distance between the gripping opening position PB and the cutting edge 75 in the plane view relationship. However, the conveying path length L1 shown in Fig. That is, the length along the carrying direction Z1 in Fig.

On the downstream side of the cutting edge 75, a fourth pass roller 74 is disposed. The fourth path roller 74 rotates and supports the cut-out side portions 12b and sends the side portions 12b to the side wind- As is well known, the side air conditioner 78 cuts the side portions 12b, which are continuously fed, into chips, and sends them to the collecting device (not shown) by the suction wind. A fifth pass roller (not shown) is provided downstream of the cutting edge 75 at a position upstream of the fourth pass roller 74 or downstream of the fourth pass roller 74, May be changed so that the transport path of the cut film 12 is directed upward, for example.

The drying chamber 18 is provided with a plurality of rollers 80 for supporting the film 12 on the peripheral surface. Among the plurality of rollers 80, there is a drive roller that rotates in the circumferential direction, and the film 12 is transported by the rotation of the drive roller. In the drying chamber 18, heated dry air is supplied. By passing the drying chamber 18, the film 12 is further dried.

Dry air at room temperature is supplied to the cooling chamber (19). The room temperature is a temperature within a range of 15 占 폚 to 30 占 폚. The film 12 is cooled by passing through the cooling chamber 19. The cooled film 12 is guided from the cooling chamber 19 to the winding device 20 and wound around the winding core 82.

Next, the operation of the above configuration will be described. The film 12 from which the grip 50 of the clip 50 is released, out of the tenter 15, is contracted by residual stress due to stretching or temperature decrease. At this time, although tension is applied to the film 12 in the carrying direction Z1 by the tension by the conveyance, tension is released in the width direction Z2 due to the grip opening of the clip 50, Therefore, a waveform deformation extending in the carrying direction Z1 occurs. In the case where the both side portions 12b of the film 12 are cut off from the central portion 12a by the cutting edge 75 in the state where the waveform deformation has occurred, defective cutting is caused by the waveform deformation. If a cutting failure occurs, clogging of the side portion 12b occurs in the next side wind-remover 78, so that the production line may be stopped. In this case, various operations are required to start again in the flexible step or the like, and time and raw materials are wasted.

The film 12 from the tenter 15 is sent to the cutting edge 75 via the first pass rollers 71 to the third pass rollers 73, (12b) is cut off from the central portion (12a). In this embodiment, the film 12 is passed through the three first pass rollers 71 to the third pass rollers 73 and the second pass rollers 72 and the third pass rollers 73 Since the film 12 is wound around and the angle of the total winding is 90 degrees or more, the corrugation is relaxed while passing through the second path roller 72 and the third path roller 73, The influence of the wave deformation is lessened and the side portions 12b can be cut smoothly.

The second path roller 72 and the third path roller 73 around which the film 12 is wound are arranged in a staggered manner with respect to the conveying path so that the wave deformation is more relaxed, The smell becomes smoother.

In the present embodiment, a clip tenter is used as the tenter 15, but a pin tenter may be used instead of the clip tenter. Also in this case, the slits 16 are used to cut off the respective side portions 12b, thereby removing the marks of maintenance by the fins. The pin tenter has a fin plate that passes through and holds a plurality of fins on the side portion 12b of the film 12, and the film 12 travels in a predetermined trajectory, and the film 12 is transported. In the case of using the pin tenter as the tenter 15 as well, the drying of the film 12 is promoted, as in the case of using the clip tenter, so that the residual solvent amount of the film 12 is, for example, 20 mass% Within the above range.

A second tenter (not shown) may be formed on the downstream side of the slitter 16, if necessary. The second tenter is used in the case of changing the optical characteristics by a specific stretching pattern or the like. Also in this second tenter, by forming the slitter 16 in the same manner as the first tenter 15, the influence of the wave deformation of the film 12 can be suppressed and cut.

When TAC is used as the polymer, it is preferable that the film 12 is a single layer structure made of TAC. On the other hand, when DAC is used as the polymer, the film 12 is preferably a multilayer structure. A preferable multilayer structure is a structure in which a layer made of TAC is formed on one surface of a layer made of DAC. A more preferable multilayer structure is a structure in which a layer made of TAC is formed on one surface and the other surface of a layer made of DAC. It is preferable that the optical film having a multilayer structure having a layer made of such a DAC is manufactured by a solution film forming method, and it is preferable that the optical film is produced by simultaneous sharing or continuous casting. The flexible die 31 in the case of the simultaneous shared die is a well-known multi-manifold die. Instead of a multi-manifold die, a feed block and a single manifold die may be used in combination. The feed block joins the supplied plurality of types of dope internally and sends the merged flow to a single manifold die.

In the above-described embodiment, the film 12 is stretched in the width direction Z2 in the solution film-forming process, but the present invention is not limited to this embodiment. For example, even in the case of so-called offline stretching in which the thermoplastic resin film once produced is stretched in the width direction Z2, the side portions 12b of the film 12 are separated from the central portion 12a by using the slitter 16 You can cut it.

The film 12 is used as an optical film. Specifically, the film 12 is particularly preferably used as a retardation film that is used in a polarizing plate and optically compensates light from a light source. Among them, it is particularly effective as a VA retardation film or an IPS retardation film.

[Example]

First, a cellulose acylate (TAC) having an acyl group substitution degree of 2.81 was prepared. In the production, sulfuric acid was used as a catalyst. The amount of this catalyst added to 100 parts by mass of the cellulose acylate is 7.8 parts by mass. The carboxylic acid serving as a raw material of the acyl substituent was added and the acylation reaction was carried out at 40 占 폚. The kind of the acyl group and the degree of substitution were adjusted by adjusting the kind and amount of the carboxylic acid. After the acylation, aging was carried out at 40 占 폚. Further, the low molecular weight component of this cellulose acylate was removed by washing with acetone.

The following dope 11 of the prescription was prepared.

(Dope)

Cellulose acylate 100 parts by mass

Additive A: A-3 of Table 1 11.3 parts by mass

Compound D: Compound represented by Formula 1 4 parts by mass

Dichloromethane 406 parts by mass

Methanol 61 parts by mass

The mat release liquid was mixed and stirred in any of the dope 11. The particulate matting agent (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd., secondary average particle size 1.0 mu m or less) was 0.13 parts by mass based on 100 parts by mass of the cellulose acylate.

Further, the additive A is polyester, and the polyester is obtained by the combination and ratio of the dicarboxylic acid and the diol shown in Table 1. In Table 1, "TPA" in the "aromatic dicarboxylic acid" column indicates terephthalic acid, and "SA" in the "aliphatic dicarboxylic acid" column indicates succinic acid. The "dicarboxylic acid ratio" column in Table 1 represents an aromatic dicarboxylic acid / aliphatic dicarboxylic acid, and the "diol ratio" column represents a diol 1 / diol 2.

Experiments 1 to 19 were conducted in which the film 12 was produced by the dope 11 using the solution film-forming equipment 10 and a film 12 having a thickness of 20, 40 and 60 탆 was obtained. The film 12 having a thickness of 20, 40 and 60 탆 is obtained by adjusting the thickness of the flexible film 32 by the flexible device 14 and changing the drawing magnification W2 / W1 in the tenter 15 have. It should be noted that the relationship between the draw ratio W2 / W1 of the film stretching device 17, the conveying path length L1 from the gripping opening position PB to the cutting edge 75, The number of pass rollers N wound around the film 12 in the conveying path and the total winding angle? In the rolled pass rollers were set as shown in the respective experiments shown in Table 2. [ Then, the stability of the cut at which the both side portions 12b were cut in the film stretching device 17 (hereinafter referred to as the cut stability) was evaluated. The thickness of the film in each experiment is shown in the column of "film thickness" in Table 2 and the number of the pass rollers wound around the film 12 in the conveying path between the tenter 15 and the cutting edge 75 (N) are shown in the column of " the number of winding rollers N ".

In Experiments 1 to 19, the winding angle of the film 12 with respect to the first path roller 71 was set to 0 deg. In Experiments 1 to 8, the second path roller 72 and the third path roller 73 are omitted in FIG. 1 to make the shape of the film conveying path straight, and the first path roller 71 and the fourth path roller 73 And a cutting blade 75 is provided between the pass rollers 74. [ In Experiment 1, the cut-off stability of the both side portions 12b was evaluated when the thickness was 60 占 퐉, the draw ratio was 1.00, and the conveying path length L1 was 0.6 m. Experiment 2 was conducted under the same conditions as Experiment 1 except that the thickness of the film in Experiment 1 was 40 占 퐉. Experiment 3 was performed under the same conditions as Experiment 1 except that the thickness of the film in Experiment 1 was 20 占 퐉. In Experiments 4 to 6, conditions were the same as those of Experiments 1 to 3 except that the draw magnifications of Experiments 1 to 3 were 1.07. Experiment 7 was conducted under the same conditions as Experiment 5 except that the stretching magnification of Experiment 5 was 1.12. Experiment 8 was performed under the same conditions as Experiment 6 except that the stretching magnification of Experiment 6 was 1.12. Experiments 9 and 10 show a reference example in which the second path roller 72 is disposed between the first path roller 71 and the fourth path roller 74 in FIG. Experiment 9 was conducted under the same conditions as Experiment 6 except that the winding angle of the second path roller 72 was 30 degrees. In Experiment 10, the conditions were the same as those of Experiment 9 except that the winding angle of the second pass roller 72 of Experiment 9 was changed to 90 degrees.

In Experiments 11 to 19, the first through fourth rollers 71 through 74 are disposed as shown in Fig. 1, and the second pass rollers 72 and the third pass rollers 73 are provided with a film 12). The sum of the winding angle of the second path roller 72 and the third path roller 73 was set to 60 deg., 90 deg., And 180 deg. In Experiment 11, except that in Experiment 6, the second path roller 72 and the third path roller 73 were added to form a Z-shaped film conveying path and the total winding angle? Was set to 60 ° The same conditions as in Experiment 6 were used. In Experiment 12, the same conditions as in Experiment 11 were used except that the total winding angle of Experiment 11 was set at 90 degrees. In Experiment 13, the same conditions as in Experiment 11 were used except that the total winding angle of Experiment 11 was set at 180 degrees. In Experiment 14, the same conditions as in Experiment 12 were used except that the conveying path length (L1) of Experiment 12 was set to 0.8 m. In Experiment 15, the same conditions as Experiment 12 were used except that the conveying path length (L1) of Experiment 12 was 1.0 m. In Experiment 16, the same conditions as in Experiment 15 were used except that the total winding angle? Of Experiment 15 was set to 180 °. In Experiment 17, conditions were the same as those of Experiment 12 except that the thickness of the film of Experiment 12 was 40 占 퐉. In Experiment 18, the conditions were the same as those of Experiment 17 except that the stretching magnification of Experiment 17 was 1.12. In Experiment 19, the conditions were the same as those of Experiment 18 except that the conveying path length (L1) of Experiment 18 was 1.0 m.

In Experiments 20 to 22, the conveyance path lengths L1 of Experiment 8 were changed to 0.6 m, 0.8 m, and 1.0 m, and the first pass rollers 71 to the fourth pass rollers 74 were disposed, The rollers 72 and the third pass rollers 73 were wound with the film 12. The same conditions as those in Experiment 8 were used except that the sum of the wrapping angles with respect to the second pass roller 72 and the third pass roller 73 was changed to 90 degrees as the total wrapping angle? Respectively.

Experiments 23 to 26 were carried out under the same conditions as Experiments 8 and 20 to 22 except that the film materials of Experiments 8 and 20 to 22 were changed from TAC to COP (cyclic olefin polymer). The COP film was obtained by forming a film according to the method described in Production Example 1 of WO2006 / 019086 in Zeonoa (registered trademark) 1020R, and the film thickness was 20 mu m.

Experiments 27 to 30 were carried out under the same conditions as Experiments 8 and 20 to 22 except that the film materials of Experiments 8 and 20 to 22 were changed from TAC to PET (polyethylene terephthalate). The PET film was formed as follows, and the film thickness was set to 20 탆. First, PET having an intrinsic viscosity of 0.64, polycondensed with a Ti compound as a catalyst, was dried at a water content of 50 ppm or less and melted in an extruder having a heater temperature of 280 ° C or higher and 300 ° C or lower. Next, the melted PET was extruded from the die portion onto the electrostatically charged cooling roll to obtain a PET film composed of a belt-like amorphous base.

The stability of the cut was evaluated based on the presence or absence of fracture, the stability of the cut line, and the roughness of the cut section. Evaluation A was performed when the film 12 was not broken, the cutting line became straight in the carrying direction Z1 and was stable, and there was no roughness on the cut surface. In addition, when the film 12 was not broken, the cutting line became straight in the carrying direction Z1 and was stable, but when there was roughness on the cut surface, it was rated B. Evaluation C was performed when the film 12 was not broken but the cutting line was meandering in the carrying direction Z1 and unstable. The meandering in the carrying direction Z1 means that the cutting line deviates in the width direction of the film 12. The cut line was unstable because the cut line did not become a straight line in the transport direction Z1 and evaluation D was made when the film 12 was broken by several hours. Further, when the film 12 was unstable because the cutting line did not become linear in the transport direction Z1 and the film 12 was broken in several minutes, evaluation E was made. The stability of the cutting line was evaluated by visually observing the side edge of the central portion 12a in which the both side portions 12b were cut off. In the roughing of the cut section, when the side portions 12b feel roughness by touching the side end face of the cut central portion 12a, or when the side face of the center portion 12a is rubbed with a black cloth, In the case of a stain. When the stability of the cut line was evaluated as unstable, the roughness of the cut section was not evaluated. When the evaluation is located in the middle of the two evaluations, it is described as A to B, for example.

The group of Experiments 1 to 10 corresponds to the reference example, and it can be seen that as the film 12 becomes thinner, the cutting stability is lowered. It can be seen that as the draw ratio increases, the cutting stability decreases. It can be seen that as the number of winding rollers N increases, the cutting stability becomes better. However, it can be seen that when the thickness of the film is 40 탆 or 20 탆 and the draw ratio is 1.07, the cutting stability is lowered.

In the groups of Experiments 1 to 6, it can be seen that as the thickness of the film becomes thinner to 60 탆, 40 탆 and 20 탆, the stability of cutting gradually decreases. Also, it can be seen that as the draw ratio increases from 1.02 to 1.07, the stability of the cut gradually decreases.

In the groups of Experiments 2, 5, 7, 3, 6 and 8, the cutting stability is gradually lowered as the draw ratio increases to 1.02, 1.07, and 1.10 even if the thickness is the same.

In the groups of Experiments 6 and 9 to 13, when the total winding angle? Is increased to 30 °, 60 °, 90 ° and 180 ° with the thickness of the film being 20 μm and the stretch magnification being 1.07, It can be seen that as the total winding angle? Increases, and as the number of winding and passing rollers N increases, the cutting stability gradually improves.

In the groups of Experiments 14 to 16, when the conveying path length L1 was made long as 0.8 m and 1.0 m while the thickness of the film was 20 m and the drawing magnification was 1.07, the conveying path length L1 became long , It can be seen that the cutting stability is gradually improved. In the groups of Experiments 17 to 19, when the thickness of the film was changed to 40 占 퐉, the stretch magnification was changed to 1.07 and 1.10, and the transport path length L1 was 0.6 m and 1.0 m, the transport path length L1 ) Becomes longer, the stability of the cutting progressively becomes better.

In the groups of Experiments 8 and 20 to 23, when the conveying path length L1 is made long as 0.6 m, 0.8 m, and 1.0 m with the thickness of the film being 20 m and the draw magnification being 1.12 times, (L1) becomes longer, the cutting stability becomes gradually better.

In the groups of Experiments 23 to 26, even when the film materials of Experiments 8 and 20 to 22 were TAC, even when they were changed to COP, the conveying path lengths L1 were 0.6 m, 0.8 m and 1.0 m , It can be seen that as the length L1 of the conveying path becomes longer, the stability of the cutting becomes gradually better. Similarly, in the groups of Experiments 27 to 30, it can be seen that, even when the film material is changed to PET, the cutting stability is gradually improved as the transport path length L1 becomes longer, like the TAC film.

From the above-described experimental results, it was found that, in a cutting process in which both sides of a thin film having a thickness of 40 탆 or less after cutting are cut by cutting blades, when the stretched film is wound on two or more pass rollers at an angle? So that the effect of the wave deformation that occurs immediately after the elongation is not transmitted to the cutting edge and the occurrence of the cutting defect is suppressed. In particular, when the stretching ratio is increased to 1.07 times or more, the occurrence of cutting defects in the thin film is suppressed. Further, in the case of producing a thinner film by raising the drawing magnification to 1.07 times or more, by setting the conveying path length L1 to 1.0 m or more, occurrence of cutting defects can be suppressed with respect to a thinner film. In addition, even when the film material is changed to COP or PET other than TAC, the occurrence of cutting defects can be suppressed in the same thin film.

10: Solution forming equipment
12: Film
12a:
12b: side
15: Tentor
16: Slitter
17: Film stretching device
71 to 74: First to fourth pass rollers
75: Cutting blade

Claims (11)

A film production method for producing a film having a thickness of 40 占 퐉 or less by stretching in the transverse direction while conveying a long thermoplastic resin film,
(A) a step of gripping both side portions of the thermoplastic resin film by a grip portion and stretching in the width direction;
(B) cutting both side portions held by the grip portion of the thermoplastic resin film with a cutting edge; And
(C) a step of winding the thermoplastic resin film on both sides of the thermoplastic resin film, which has been gripped on both sides in the step A, on two or more path rollers disposed apart from each other in the carrying direction and transferring the thermoplastic resin film to the cutting blade, Wherein the winding step angle is 90 DEG or more,
To form a film. The method according to claim 1,
Wherein the step A is to widen the width of the thermoplastic resin film to 1.07 times or more. 3. The method according to claim 1 or 2,
Wherein the conveying path length of the thermoplastic resin film from the gripping opening position of the thermoplastic resin film by the gripping portion to the cutting edge is 1.0 m or more. 3. The method according to claim 1 or 2,
Wherein the gripping portion is a clip holding both side portions of the thermoplastic resin film. The method of claim 3,
Wherein the gripping portion is a clip holding both side portions of the thermoplastic resin film. 3. The method according to claim 1 or 2,
Wherein the thermoplastic resin film is a cellulose acylate film. A film stretching apparatus for producing a film having a thickness of 40 탆 or less by stretching in the transverse direction while conveying a long thermoplastic resin film,
A tenter for gripping both side portions of the thermoplastic resin film by a grip portion and stretching in the width direction;
A cutting blade for cutting the both side portions gripped by the grip portion of the thermoplastic resin film; And
And two or more path rollers disposed at a distance from the gripping opening position of the both side portions by the gripping portion from the cutting edge to the cutting edge, wherein the total winding angle of the thermoplastic resin film in the two or more path rollers is 90 Or more,
The film stretching device comprising: 8. The method of claim 7,
Wherein the tenter extends the width of the thermoplastic resin film to 1.07 times or more. 9. The method according to claim 7 or 8,
And the conveying path length of the thermoplastic resin film from the gripping open position to the cutting edge is 1.0 m or more. 9. The method according to claim 7 or 8,
Wherein the gripping portion is a clip holding both side portions of the thermoplastic resin film. 10. The method of claim 9,
Wherein the gripping portion is a clip holding both side portions of the thermoplastic resin film.

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