JP2009090540A - Manufacturing process of thermoplastic resin film and thermoplastic resin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a thermoplastic resin film which has no level unevenness, no cool wrinkle or the like and which is suitable for optical application by improving an exfoliation state of the film when the thermoplastic resin film is manufactured by a molten film-forming method. <P>SOLUTION: A manufacturing method of the thermoplastic resin film includes a process of ejecting a molten thermoplastic resin in a film-shape from a die 16 and cooling the ejected film 12A by carrying out contact transportation with a first cooling roller 18, a second cooling roller 20 and a third cooling roller 22. In this manufacturing method of the thermoplastic resin film, adhesion force N (kPa) at an exfoliated part 44 of the film 12A toward the first cooling roller 18, the second cooling roller 20 and the third cooling roller 22 is in a range satisfying formula: 0 kPa<N<30 kPa. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a thermoplastic resin film and a thermoplastic resin film, and more particularly to a technique for producing a film in which the produced thermoplastic resin film is used for optical applications such as a liquid crystal display device.

  Thermoplastic resins such as cellulose resins and cyclic olefin resins are widely used as films for optical applications. In particular, a cellulose resin or a cyclic olefin resin film is used as an optical film for liquid crystal display devices because of its transparency, toughness, and optical isotropy.

  As a method for producing a thermoplastic resin film, there is a method in which a molten thermoplastic resin is discharged from a die into a film shape, and the discharged film is contacted and conveyed by a plurality of cooling rolls to perform multi-stage cooling (for example, a melt-processed product). Membrane method). The unstretched thermoplastic resin film produced in this way is used for a protective film of a liquid crystal display device, for example. A film obtained by stretching an unstretched thermoplastic resin film to develop retardation is used as a retardation film of a liquid crystal display device.

  However, when the film is cooled, there is a problem that wrinkles are generated in the film due to shrinkage and expansion of the film accompanying a temperature change, and the surface state of the film is deteriorated. In particular, for a thermoplastic resin film used for optical applications, the above-described step unevenness becomes a fatal defect in optical characteristics.

  As a countermeasure, for example, Patent Document 1 proposes that when the film is cooled and solidified by a cooling roll, the optical phase difference is reduced by making both ends in the film width direction higher than the center. Yes.

Patent Document 2 proposes to suppress the occurrence of soot by defining the temperature of the cooling roll located on the most downstream side in multi-stage cooling.
JP 2003-33962 A JP 2003-245966 A

  However, Patent Documents 1 and 2 show a certain effect in reducing wrinkles, but when the cooled film is peeled off from the cooling roll, if the peeled state is unstable, step unevenness occurs in the longitudinal direction of the film. There was a problem that the film quality deteriorated. The film peeling state can be adjusted to some extent by the surface temperature of the cooling roll. However, the setting of temperature conditions is actually performed by trial and error while actually forming a film, and is not efficient.

  Further, when the surface temperature of the cooling roll is extremely lowered to improve the peeled state, there is a problem that a cooling flaw is generated due to rapid cooling or the touch effect is weakened in the touch roll film forming method. For this reason, it has been extremely difficult to improve the stripped state only with the surface temperature of the cooling roll without causing the above-mentioned cooling soot.

  The present invention has been made in view of such circumstances, and improves the state of film peeling when a thermoplastic resin film is produced by a melt film-forming method, and is suitable for optical applications free from step unevenness and cooling. An object of the present invention is to provide a method for producing a thermoplastic resin film capable of obtaining a simple thermoplastic resin film.

  In order to achieve the above object, claim 1 of the present invention comprises a step of discharging a molten thermoplastic resin from a die into a film, and cooling the discharged film by contact conveyance to one or more cooling rolls. In the method for producing a thermoplastic resin film, a method for producing a thermoplastic resin film, characterized in that an adhesive force N (kPa) in a peeled portion of the film with respect to the cooling roll is in a range of 0 kPa <N <30 kPa. provide.

  The present inventors have found that the peeled state of the film is improved when the adhesive strength of the film at the peeled portion to the cooling roll is within a certain range. According to the first aspect, the adhesive strength N (kPa) at the peeled portion of the film with respect to the cooling roll is set to a range of 0 kPa <N <30 kPa. Thereby, even if it does not necessarily cool a cooling roll rapidly, the peeling state of a film can be made favorable. Therefore, step unevenness can be suppressed without generating a cooling rod. The adhesive strength is more preferably in the range of 10 kPa <N <20 kPa.

  The stripped portion specifically refers to a peeled line extending in the film width direction.

  The adhesive strength can be measured by, for example, a tacking tester. Moreover, the said adhesive force can be adjusted by changing the temperature of a thermoplastic resin, the surface temperature of a cooling roll, surface roughness, etc., for example.

  A second aspect of the present invention is the method according to the first aspect, wherein one cooling roll is provided, and the surface temperature T1 (° C.) of the cooling roll is Tg−70 <T1 <relative to the glass transition temperature Tg (° C.) of the thermoplastic resin. Tg is satisfied.

  A third aspect of the present invention is the method according to the first aspect, wherein a plurality of the cooling rolls are provided, and the surface temperature T1 (° C.) of the cooling roll located on the most upstream side in the transport direction of the film is equal to the glass transition temperature Tg ( C.), Tg−70 <T1 <Tg is satisfied.

  According to claims 2 and 3, the surface temperature T1 (° C.) of the cooling roll on which the film discharged from the die first lands (in the case of multi-stage cooling, the cooling roll located on the most upstream side in the film transport direction). Since the above range is satisfied, the molten thermoplastic resin discharged from the die can be prevented from being rapidly cooled, and the generation of cooling soot can be suppressed.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the adhesive force is adjusted by any one or more of a surface temperature, a surface roughness, and a temperature of the thermoplastic resin of the cooling roll. To do.

  The fourth aspect exemplifies a preferable operation factor for adjusting the adhesive strength.

  A fifth aspect of the present invention is characterized in that, in any one of the first to fourth aspects, the adhesive force is adjusted by applying cooling air to the stripped portion.

  According to the fifth aspect, the peeling state can be improved in a short time and with less energy by locally cooling the peeled portion of the film.

  A sixth aspect of the present invention is the method according to any one of the third to fifth aspects, wherein the surface temperature of the cooling roll on the downstream side in the conveyance direction of the film is the surface of the cooling roll on the upstream side in the conveyance direction. The temperature is the same as or lower than the surface temperature of the cooling roll on the upstream side in the transport direction.

  According to the sixth aspect, since the cooling is gradually performed every time it passes through the plurality of cooling rolls, it is possible to prevent a sudden temperature change and to suppress the cooling soot and the like.

  A seventh aspect of the present invention is characterized in that, in any one of the first to sixth aspects, the cooling roll is a touch roll type. In such a touch roll method, since the surface pressure is uniformly applied to the molten film discharged from the die, in-plane Re and Rth unevenness and unevenness unevenness can be reduced. The resin temperature at the time of roll touch is preferably equal to or higher than the Tg (glass transition temperature) of the resin.

  An eighth aspect is characterized in that, in any one of the first to seventh aspects, the thermoplastic resin is a cellulose resin or a cyclic olefin resin.

  This is because, among thermoplastic resin films, in particular, a cellulose resin or a cyclic olefin resin film is suitable as a film for optical use because of its transparency, toughness, and optical isotropy.

  A ninth aspect of the present invention is the method for producing a thermoplastic resin film according to any one of the first to eighth aspects, wherein the thermoplastic resin film is an optical film used for optical applications.

  This is because if a thermoplastic resin film for optical use is produced by the production method of the present invention, the peeled state can be stabilized, and a good optical film having a planar shape free from step unevenness and cooling flaws can be produced. Examples of the optical film include a retardation film, a polarizing plate, a polarizing plate protective film, and an antireflection film.

  According to a tenth aspect of the present invention, there is provided a thermoplastic resin film produced by the method for producing a thermoplastic resin film according to any one of the first to ninth aspects, in order to achieve the object. To do. The thermoplastic resin film produced in this way has no unevenness or cooling flaws and has a good surface shape.

  According to the present invention, it is possible to improve the film peeling state when a thermoplastic resin film is produced by a melt film-forming method, and to obtain a thermoplastic resin film suitable for optical applications free from step unevenness and cooling. it can.

  Hereinafter, preferred embodiments of a method for producing a thermoplastic resin film according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing an example of a production apparatus for carrying out the method for producing a thermoplastic resin film of the present invention. In this embodiment, an example of producing a cellulose acylate film is shown, but the present invention is not limited to this, and can be applied to other cyclic olefin-based thermoplastic resin films.

As shown in FIG. 1, the manufacturing apparatus 10 is mainly discharged from an extruder 14 that melts the cellulose acylate resin 12, a die 16 that discharges the melted cellulose acylate resin 12 into a film, and a die 16. A plurality of cooling rolls 18, 20, and 22 that cool the cellulose acylate film 12 </ b> A (hereinafter referred to as a film 12 </ b> A) in a high-temperature melt state, a peeling roll 24 that peels the film 12 </ b> A from the last cooling roll 22, and the cooled A winder 26 that winds up the film 12A and the like are configured. Although FIG. 1 shows a case where three stages are provided as the cooling rolls 18, 20, 22, the present invention is not limited to this, and one stage or more may be used.

  FIG. 2 is a cross-sectional view showing the configuration of the extruder 14. As shown in the figure, in the cylinder 32 of the extruder 14, a single screw 38 having a flight 36 attached to a screw shaft 34 is provided. The single screw 38 is rotated by a motor (not shown). A hopper (not shown) is attached to the supply port 40 of the cylinder 32. Then, the cellulose acylate resin 12 is supplied from the hopper into the cylinder 32 through the supply port 40.

  Inside the cylinder 32, in order from the supply port 40 side, a supply unit (region indicated by A) for quantitatively transporting the cellulose acylate resin supplied from the supply port 40, and a compression unit (B) for kneading and compressing the cellulose acylate resin And an area for measuring the kneaded and compressed cellulose acylate resin (area indicated by C). The cellulose acylate resin melted by the extruder 14 is continuously sent from the discharge port 42 to the die 16.

The screw compression ratio of the extruder 14 is preferably set to 2.5 to 4.5, and L /
D is preferably set to 20 to 70. Here, the screw compression ratio is the supply unit A.
And the measuring unit C, ie, the volume per unit length of the supply unit A divided by the volume per unit length of the measuring unit C, the outer diameter d1 of the screw shaft 34 of the supplying unit A, the measuring unit C Is calculated using the outer diameter d2 of the screw shaft 34, the groove part diameter a1 of the supply part A, and the groove part diameter a2 of the measuring part C. L / D is the ratio of the cylinder length (L) to the cylinder inner diameter (D) in FIG. Moreover, it is preferable that extrusion temperature is set to 190-240 degreeC.

And it is sent to the die | dye 16 via the cellulose acylate resin 12 fuse | melted by the extruder 14, and the piping 44 (refer FIG. 1), and is discharged in film form from a die | dye discharge port. Die 16
The fluctuation of the discharge pressure discharged from the nozzle is preferably within a range of 10%.

  As shown in FIG. 1, three cooling rolls 18, 20, and 22 that perform multistage cooling are disposed on the downstream side of the die 16. Hereinafter, the cooling rolls 18, 20, and 22 arranged in three stages will be referred to as a first cooling roll 18, a second cooling roll 20, and a third cooling roll 22, respectively, in order from the upstream side in the film transport direction.

  In the first cooling roll 18, the film 12A is cooled and solidified by a touch roll method to form a film. In the touch roll method, the film 12A from the die 16 is sandwiched between the first cooling roll 18 and the touch roll 28 to be cooled and solidified.

  The touch roll 28 preferably has elasticity in order to reduce the residual strain generated when the film 12A that has come out of the die 16 is sandwiched between the rolls. In order to give elasticity to the roll, it is necessary to make the outer cylinder thickness of the roll thinner than a normal roll, and the wall thickness Z of the outer cylinder is preferably 0.05 mm to 7.0 mm. For example, an elastic body layer is provided by reducing the thickness of the outer cylinder, or an elastic body layer is provided on a metal shaft, and the outer cylinder is placed thereon, and the liquid medium layer is filled between the elastic body layer and the outer cylinder. The thing etc. which enabled the touch roll film forming by the ultra-thin outer cylinder are mentioned.

  As described above, since the fluid is filled inside the thin outer cylinder, the touch roll 28 is elastically deformed into a concave shape by the pressing when it is brought into contact with the first cooling roll 18. Therefore, since the touch roll 28 and the first cooling roll 18 are in surface contact, the pressure is dispersed and a low surface pressure can be achieved. For this reason, the fine unevenness | corrugation of the surface can be corrected, without leaving a residual distortion in the film pinched | interposed between these.

  The linear pressure of the touch roll 28 is preferably 3 to 100 kg / cm. The linear pressure is a value obtained by dividing the force applied to the touch roll 28 by the width of the discharge port of the die 16. By adjusting such a linear pressure, Rth can be adjusted. Specifically, the surface orientation of the cellulose acylate film by the surface pressure of the touch roll 28 can be promoted, and Rth can be increased. Further, since the surface pressure is uniformly applied as a whole, in-plane Re and Rth unevenness and fine unevenness and thickness unevenness formed on the film 12A can be reduced.

  Thus, the film 12A cooled and solidified by the first cooling roll 18 is conveyed to the adjacent second cooling roll 20 and further cooled. At this time, if the peeling state of the film 12A from the first cooling roll 18 is bad, it causes unevenness in the film 12A. The same applies to the stripped portions of the second and third cooling rolls 20 and 22.

  FIG. 3 is an enlarged cross-sectional view of the first and second cooling rolls 18 and 20.

  In this embodiment, as shown in FIG. 3, as a condition for stabilizing the peeling state in the peeling portion 44, the adhesive force N (kPa) in the peeling portion 44 of the film 12 </ b> A with respect to the first cooling roll 18 is set to 0 kPa < The range is N <30 kPa. The same applies to the stripped portions of the second and third cooling rolls 20 and 22.

  That is, the adhesive strength N of the film 12A in the stripped portion 44 is set to a range of 0 kPa <N <30 kPa by changing the surface temperature, surface roughness, temperature of the film 12A, etc. of the first cooling roll 18. adjust. When the adhesive strength N is 30 kPa or more, it becomes difficult to peel off from the first cooling roll 18, and only a part thereof is peeled off, resulting in damage or wrinkles. On the other hand, when the adhesive strength N becomes 0 kPa, the film 12A does not come into uniform contact with the first cooling roll 18, so that there is a problem that the temperature distribution is generated and wrinkles or the thickness unevenness of the film 12A cannot be reduced. is there.

  The adhesive strength is more preferably in the range of 10 kPa <N <20 kPa. The adhesive strength can be measured by, for example, a tacking tester.

  As an example of adjusting the adhesive force according to the surface temperature T1 of the first cooling roll 18, there is a method of increasing the surface temperature T1 when increasing the adhesive force and decreasing the surface temperature T1 when decreasing the adhesive force. .

  The surface temperature T1 (° C.) of the first cooling roll 18 is preferably in the range of Tg−70 <T1 <Tg with respect to the glass transition temperature Tg (° C.) of the film 12A, and Tg-40 <T1 <Tg. A range of −5 is more preferable. The touch roll 28 is preferably set to the same temperature as the first cooling roll 18. The temperature of the touch roll 28 can be controlled by passing a temperature-controlled liquid or gas through the roll. Thereby, the rapid cooling when the film 12A discharged from the die 16 lands on the first cooling roll 18 can be suppressed, and it is possible to effectively suppress the generation of cooling soot on the film 12A at the time of landing.

  Further, when the surface temperature of the first cooling roll 18 is T1, and the surface temperature of the second cooling roll 20 adjacent to the first cooling roll 18 is T2, the temperature difference ΔT (T1−T2) is It is preferable to be in the range of 0 (° C.) <ΔT <20 (° C.). The temperature difference ΔT between the second and third cooling rolls 20 and 22 is preferably the same as this. Thereby, also when the film 12A lands on the second and third cooling rolls 20 and 22, the cooling soot can be suppressed without being rapidly cooled.

  The surface temperature T1 and the like of the first cooling roll 18 may be grasped by measuring in advance by a preliminary test or the like, or a non-contact type thermometer such as an infrared radiation thermometer is provided in the manufacturing apparatus, The medium temperature of the cooling roll may be automatically controlled based on the measurement result.

  As an example of adjusting the adhesive strength according to the surface roughness of the first cooling roll 18, there is a method of decreasing the surface roughness when increasing the adhesive strength and increasing the surface roughness when decreasing the adhesive strength. .

  The surface roughness Ra (μm) of the first cooling roll 18 is preferably in the range of 0.01 (μm) <Ra <1.0 (μm), for example. This is because if the surface roughness Ra exceeds 1.0 (μm), the surface roughness is transferred to the film 12A, resulting in a planar failure.

  In order to further stabilize the peeled state with respect to the first cooling roll 18, the peeled portion can be locally cooled. As such a method, for example, there is a method of applying cooling air to the peeled portion of the film 12A by the cooling air blowing means 30.

  As shown in FIG. 1, the cooling air blowing means 30 may be installed for each cooling roll, or may be installed on a specific cooling roll (for example, the first cooling roll 18) whose peeling state is likely to be unstable. May be.

  The cooling air is preferably clean air, and specifically, the cleanliness of the cooling air is preferably ISO class 4 or less. This is because, if it is larger than ISO class 4, particles of 5 μm or more may adhere to the product as foreign matter. However, since the adhesion behavior varies depending on the material, it is not limited to this range. Moreover, since the stripped state becomes unstable when the temperature of the cooling air is higher than the surface temperature of the cooling roll, the temperature of the cooling air is preferably lower than the surface temperature of the cooling roll.

  As air blowing conditions, it is preferable that the maximum wind speed just before the film 12A is 1 to 30 m / sec. This is because the film 12A is deformed when the wind speed is high, and a sufficient effect may not be obtained when the wind speed is low. It is preferable that the temperature of air is below Tg of the film 12A, below the surface temperature of the cooling roll, and above the ambient temperature of the cooling roll. Thus, the optimum stripping conditions can be determined by adjusting the air temperature and the wind speed.

  Moreover, it is preferable to set as temperature conditions of the multistage cooling by a some cooling roll so that the surface temperature of a cooling roll may become low sequentially from the upstream of a film conveyance direction. Thereby, the high-temperature film 12A discharged from the die 16 is cooled in multiple stages by the three cooling rolls 18, 20, and 22 arranged in multiple stages.

  Thus, in this Embodiment, in the solution film forming process which forms film 12A, the adhesive force N of the peeling part 44 with respect to the cooling roll of film 12A, and the temperature conditions of each cooling roll are set as mentioned above. As a result, the peeled state can be stabilized without quenching, so that step unevenness can be suppressed without producing a cooling rod. Accordingly, it is possible to produce a cellulose acylate film that is excellent in surface shape and suitable for optical applications.

  In addition, the film 12A produced as described above in the melt film-forming process can be produced as a retardation film having excellent optical properties by performing a longitudinal stretching process and a lateral stretching process as shown in FIG. . In this case, after the film 12A is manufactured by the melt film-forming process, the film may be wound after the longitudinal stretching process and the lateral stretching process are continuously performed without being wound around the winder 26 once.

In the longitudinal stretching step, after the film 12A is preheated, the film 12A is wound around two nip rolls in a heated state. The nip roll on the outlet side transports the film 12A at a faster transport speed than the nip roll on the inlet side.
A is stretched in the longitudinal direction. In this case, a heating furnace is provided in the longitudinal stretching process section, and the above-described nip rolls are arranged on the inlet side and the outlet side of the heating furnace, respectively. It is preferable to perform long span stretching.
The longitudinally stretched film 12A is sent to the transverse stretching step and is transversely stretched in the width direction. In the transverse stretching step, for example, a tenter can be suitably used.
Both ends in the width direction of 2A are gripped by clips and stretched in the lateral direction (width direction). By this transverse stretching, the retardation Rth can be further increased.

By performing the above-described longitudinal and lateral stretching treatments, a stretched cellulose acylate film expressing retardation Re and Rth can be obtained. In the stretched cellulose acylate film, Re is 0 nm to 500 nm, more preferably 10 nm to 400 nm,
More preferably, 15 nm to 300 nm, Rth is 30 nm to 500 nm,
More preferably, it is 50 nm or more and 400 nm or less, More preferably, it is 70 nm or more and 350 nm
It is as follows. Of these, those satisfying Re ≦ Rth are more preferred, and more preferably R ≦ Rth.
Those satisfying e × 2 ≦ Rth are more preferable. In order to realize such a high Rth and low Re, it is preferable to stretch the film that has been longitudinally stretched as described above in the transverse (width) direction. That is, the difference in orientation between the vertical direction and the horizontal direction becomes the difference in retardation (Re) in the plane, but by stretching in the horizontal direction that is the orthogonal direction in addition to the vertical direction, the difference in the vertical and horizontal orientation is reduced. The surface orientation (Re) can be reduced by reducing the size. On the other hand, since the area magnification increases by stretching in addition to the length, the orientation in the thickness direction increases as the thickness decreases, and Rth can be increased.

Furthermore, it is preferable that the variation of Re and Rth depending on the location in the width direction and the longitudinal direction is 5% or less, more preferably 4% or less, and still more preferably 3% or less. Further, the orientation angle is preferably 90 ° ± 5 ° or less or 0 ° ± 5 ° or less, more preferably 90 ° ±
3 ° or less or 0 ° ± 3 ° or less, more preferably 90 ° ± 1 ° or less or 0 ° ± 1 ° or less. By performing such stretching treatment, bowing can be reduced, and the straight line drawn along the width direction on the surface of the cellulose acylate film 12 before entering the tenter is deformed into a recess after stretching is completed. The bowing distortion obtained by dividing the deviation by the width is 10% or less, preferably 5% or less, more preferably 3% or less.

  Hereinafter, various materials used in the present invention will be described.

  It does not specifically limit as a thermoplastic resin used by this invention, A well-known thermoplastic resin can be used. Among these, when manufacturing various optical films used for liquid crystal displays and the like, cellulose acylate resins and cyclic olefin resins are suitably used as the thermoplastic resin.

  Examples of the cellulose acylate resin include the following. That is, the cellulose acylate satisfying all the requirements represented by the following formulas (1) to (3) is preferable.

2.0 ≦ X + Y ≦ 3.0 Formula (1)
0 ≦ X ≦ 2.0 Formula (2)
1.2 <= Y <= 2.9 ... Formula (3)
(In the above formulas (1) to (3), X represents the substitution degree of the acetate group, and Y represents the total substitution degree of the propionate group, butyrate group, pentanoyl group, and hexanoyl group.)
Thus, introducing a propionate group, a butyrate group, a pentanoyl group, and a hexanoyl group into cellulose acylate is preferable because the melting temperature can be lowered and thermal decomposition accompanying melt film formation can be suppressed. These cellulose acylates may be used alone or in combination of two or more. Further, a polymer component other than cellulose acylate may be appropriately mixed. Note that the cellulose acylate raw material cotton and the synthesis method are also described in detail on pages 7 to 12 of the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Institute of Invention). ing.

  As the cyclic olefin resin (cycloolefin resin), any of cycloolefin resin-A and cycloolefin resin-B described later can be preferably used.

  Examples of the cycloolefin resin (cycloolefin resin-A / ring-opening polymerization type) include (1) a ring-opening (co) polymer of a norbornene monomer, such as maleic acid addition and cyclopentadiene addition as required. After polymer modification, hydrogenated resin, (2) resin obtained by addition polymerization of norbornene monomer, and (3) addition copolymerization with norbornene monomer and olefin monomer such as ethylene or α-olefin. Resins etc. can be mentioned. The polymerization method and the hydrogenation method can be performed by conventional methods.

  Examples of the norbornene-based monomer include norbornene and alkyl and / or alkylidene substituted products thereof such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, and 5-butyl- 2-Norbornene, 5-ethylidene-2-norbornene, etc. Polar group substitution products such as halogens; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc .; dimethanooctahydronaphthalene, alkyl and / or alkylidene substitution thereof And polar group substituents such as halogen, for example, 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-ethyl -1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahi Lonaphthalene, 6-ethylidene-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano -1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a -Octahydronaphthalene, 6-pyridyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5 8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, etc .; adducts of cyclopentadiene and tetrahydroindene, etc .; 3-pentamers of cyclopentadiene, such as 4,9 : 5,8-dimethano-3a, 4,4a, 5 , 8a, 9,9a-octahydro-1H-benzoindene, 4,11: 5,10: 6,9-trimethano-3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11, 11a-dodecahydro-1H-cyclopentanthracene; and the like.

  Examples of the cycloolefin resin (cycloolefin resin-B / ring-opening polymerization type) include those represented by the following general formulas (1) to (4). Of these, the following general formula (1) Those represented are particularly preferred.

[In the general formulas (1) to (4), A, B, C and D represent a hydrogen atom or a monovalent organic group, and at least one of these is a polar group. ]
As a weight average molecular weight of these cycloolefin resin, 5000-1 million are preferable normally, More preferably, it is 8000-200000.

  Examples of cycloolefin resins include JP-A-60-168708, JP-A-62-252406, JP-A-62-2252407, JP-A-2-133413, JP-A-63-145324. Examples thereof include resins described in JP-A-63-264626, JP-A-1-240517, and JP-B-57-8815. Among these resins, those obtained by addition polymerization of norbornene monomers are particularly preferable.

  The glass transition temperature (Tg) of these cycloolefin resins is preferably 80 ° C. or higher and 230 ° C. or lower, more preferably 100 ° C. or higher and 200 ° C. or lower, and further preferably 120 ° C. or higher and 180 ° C. or lower. The saturated water absorption is preferably 1% by mass or less, and more preferably 0.8% by mass or less. The glass transition temperature (Tg) and saturated water absorption of the cycloolefin resins represented by the general formulas (1) to (4) can be controlled by selecting the type of the substituents A, B, C, and D. .

  As mentioned above, although preferable embodiment of the manufacturing method of the thermoplastic resin film which concerns on this invention was described, this invention is not limited to the said embodiment, Various aspects can be taken.

  For example, in the present embodiment, an example in which multi-stage cooling is performed with a plurality of cooling rolls has been described. However, the present invention is not limited to this, and the present invention can also be applied to the case of cooling with one cooling roll.

  In the present embodiment, the example in which the surface temperature and the surface roughness of the cooling roll are adjusted to adjust the adhesive strength to the above range is shown, but the present invention is not limited to this. For example, the temperature of the film 12A (resin temperature) ) And the composition may be adjusted. Further, the adhesive force can be adjusted by decreasing the film forming speed to reduce the adhesive force. In addition, you may adjust not only one operation factor but arbitrary several operation factors.

  In the present embodiment, the example of cooling with the touch roll type cooling roll has been described, but the present invention is not limited to this, and as shown in FIG. 5, the cooling is performed with a general casting drum type cooling roll. It can also be applied to.

  The present invention is suitable for optical films requiring high quality, for example, retardation films, polarizing plates, polarizing plate protective films, antireflection films, liquid crystal and electroluminescent display element substrates, and the like.

  Hereinafter, the features of the present invention will be described more specifically with reference to examples. However, the scope of the present invention should not be construed as being limited by the specific examples shown below.

(Example 1)
In this example, in the manufacturing apparatus 10 provided with the cooling process of the casting roll method of FIG. 5, the surface condition of the manufactured film 12 </ b> A is obtained by implementing the adhesive force and cooling temperature conditions of the film 12 </ b> A according to the present invention. It was tested how it was improved. In this embodiment, the number of cooling rolls in FIG. 5 is two.

  As the resin, TOPAS # 6013 (manufactured by Daicel Chemical Industries, Tg: 136 ° C.) was used, and the resin temperature when discharged from the die 16 was 270 ° C. The film forming speed of the film 12A was 10 m / min.

  The surface temperature T1 of the first cooling roll 18 was 50 ° C., and the surface roughness was 0.03 μm. The surface temperature T2 of the second cooling roll 20 was set to 60 ° C.

  Moreover, the cooling air was applied to the stripped portions of the first, second, and third cooling rolls 18, 20, and 22 by the cooling air blowing means 30 shown in FIG. As the cooling air, clean air having a temperature of 40 ° C., a wind speed of 10 m / second at the contact portion with the film 12A, and a cleanliness level of ISO class 4 or less was used. At this time, the adhesive force in the peeling part of the 1st cooling roll 18 was 5 kPa.

  In addition, the adhesive force was measured as follows by a tacking tester manufactured by Rhesca. That is, as shown in FIG. 6, first, the heating stage 52 is set to the resin temperature (270 ° C. in this embodiment), and the probe 54 is set to the surface temperature T1 of the first cooling roll 18 (50 ° C. in this embodiment). Set. Then, the film 12A was placed on the heating stage 52, the probe 54 was brought into contact with the film 12A, and then separated, and the maximum value of the separated force was defined as the adhesive force N. The surface roughness was measured with a known surface roughness meter.

  The surface condition of the film 12A thus formed was evaluated according to the following criteria for each of step unevenness, cooling rod, and touch unevenness.

0: No step unevenness, cooling flaw or touch unevenness 1 ... Very little step unevenness, cooling flaw or touch unevenness 2 ... Little step unevenness, cooling flaw or touch unevenness 3 ... Step unevenness, cooling flaw or touch unevenness 4 ... Slightly uneven step, cooling flaw, or touch unevenness 5 ... Very large step unevenness, cooling flaw, or touch unevenness Of the above six-step evaluation, if it is step 4 or less, it is a level that does not cause a problem as a product.

(Example 2)
The same procedure as in Example 1 was performed except that the surface temperature T1 of the first cooling roll 18 was 100 ° C. and the adhesive strength was 10 kPa.

(Example 3)
The same procedure as in Example 1 was performed except that the film was formed in the multi-stage cooling process of the touch roll type in FIG. The surface temperature of the touch roll 28 was set to 100 ° C., which is the same as that of the first cooling roll 18.

Example 4
The same operation as in Example 3 was performed except that the surface temperature T2 of the second cooling roll 20 was set to 90 ° C.

(Example 5)
The same procedure as in Example 1 was performed except that the cooling air was not applied to the stripped portions of the first, second, and third cooling rolls 18, 20, and 22 by the cooling air blowing means 30 shown in FIG. The adhesive strength at this time was 15 kPa.

(Comparative Example 1)
Example 1 was performed except that the surface temperature T1 of the first cooling roll 18 was set to 150 ° C. and the surface temperature T2 of the second cooling roll 20 was set to 160 ° C. so that the adhesive strength was 180 kPa.

(Comparative Example 2)
The same procedure as in Example 1 was performed except that the surface temperature T1 of the first cooling roll 18 was set to 100 ° C. and the surface temperature T2 of the second cooling roll 20 was set to 110 ° C. so that the adhesive strength was 40 kPa.

(Comparative Example 3)
The same procedure as in Example 3 was performed except that the touch roll 28 was roll-touched so that the adhesive strength was 200 kPa.

(Comparative Example 4)
Example 4 was repeated except that cooling air was not blown. In addition, the adhesive force of the 1st cooling roll 18 at this time was 50 kPa.

  Table 1 shows test conditions and test results.

  As can be seen from Table 1, in Examples 1 to 5 satisfying the range of the adhesive strength of the present invention, both step unevenness and cooling rods were extremely small, and a good planar film was obtained. Also, in Examples 3 and 4 cooled by the touch roll method, both the step unevenness and the cooling flaw were small as in the case of the casting roll method, and no touch unevenness was observed. In particular, even in Example 5 in which the cooling air was not locally applied to the peeled portions of the first, second, and third cooling rolls 18, 20, and 22, the adhesive strength was within the scope of the present invention, so Both were very few and good results were obtained.

  On the other hand, in Comparative Examples 1 to 4 that do not satisfy the range of the adhesive strength of the present invention, the adhesive strength in the peeled portion of the first cooling roll 18 exceeded 30 kPa, so the film 12A was stable in the first cooling roll 18. Could not be peeled off, and a lot of unevenness and cooling defects occurred. In the touch roll method, many touch unevenness occurred.

  From the above, it has been found that by applying the present invention, it is possible to form a film having an excellent surface shape such as step unevenness, cooling rod, touch unevenness (in the touch roll method) and the like.

It is a whole block diagram which shows an example of the manufacturing apparatus of the thermoplastic resin film in this embodiment. It is sectional drawing which shows the structure of the extruder of this embodiment. It is an expanded sectional view of the cooling roll of FIG. It is a block diagram in the case of carrying out the longitudinal stretch and the lateral stretch of the film manufactured in this embodiment. It is a whole block diagram which shows another aspect of the manufacturing apparatus of a thermoplastic resin film. It is sectional drawing explaining the testing apparatus used for a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Manufacturing apparatus of a thermoplastic resin film, 12 ... Cellulose acylate resin, 12A ...
Film, 14 ... Extruder, 16 ... Die, 18 ... First cooling roll, 20 ... Second cooling roll, 22 ... Third cooling roll, 24 ... Peeling roll, 26 ... Winding machine, 28 ... Touch roll 30 ... Cooling air blowing means, 44 ... Stripped part

Claims (10)

In the method for producing a thermoplastic resin film comprising a step of discharging a molten thermoplastic resin from a die into a film, and cooling the discharged film by contact conveyance to one or more cooling rolls,
The method for producing a thermoplastic resin film, wherein an adhesive force N (kPa) at a peeled portion of the film with respect to the cooling roll is in a range of 0 kPa <N <30 kPa.   One cooling roll is provided, and the surface temperature T1 (° C.) of the cooling roll satisfies Tg−70 <T1 <Tg with respect to the glass transition temperature Tg (° C.) of the thermoplastic resin. Item 2. A method for producing a thermoplastic resin film according to Item 1.   A plurality of the cooling rolls are provided, and the surface temperature T1 (° C.) of the cooling roll located on the most upstream side in the film transport direction is Tg−70 <with respect to the glass transition temperature Tg (° C.) of the thermoplastic resin. T1 <Tg is satisfy | filled, The manufacturing method of the thermoplastic resin film of Claim 1 characterized by the above-mentioned.   The thermoplasticity according to any one of claims 1 to 3, wherein the adhesive force is adjusted by any one or more of a surface temperature of the cooling roll, a surface roughness, and a temperature of the thermoplastic resin. A method for producing a resin film.   The said adhesive force is adjusted by applying cooling air to the said peeling part, The manufacturing method of the thermoplastic resin film of any one of Claims 1-4 characterized by the above-mentioned.   Of the adjacent cooling rolls, the surface temperature of the cooling roll on the downstream side in the transport direction of the film is the same as the surface temperature of the cooling roll on the upstream side in the transport direction or the surface temperature of the cooling roll on the upstream side in the transport direction. The method for producing a thermoplastic resin film according to any one of claims 3 to 5, wherein the temperature is also low.   The said cooling roll is a touch roll system, The manufacturing method of the thermoplastic resin film of any one of Claims 1-6 characterized by the above-mentioned.   The method for producing a thermoplastic resin film according to any one of claims 1 to 7, wherein the thermoplastic resin is a cellulose resin or a cyclic olefin resin.   The said thermoplastic resin film is an optical film used for an optical use, The manufacturing method of the thermoplastic resin film of any one of Claims 1-8 characterized by the above-mentioned.   A thermoplastic resin film produced by the method for producing a thermoplastic resin film according to claim 1.

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