JP2005305637A - Polymer film cutting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excellent cutting processing part, by restraining the occurrence of cut powder and chips when cutting a polymer film. <P>SOLUTION: Heating is performed before cutting so that the temperature T (an unit ; °C) of the polymer film 31 in cutting satisfies (Tg-90)≤T ≤(Tg-30). This heating is performed by blowing hot air, and the hot air is blown upon both surfaces of the film 31 from a duct 41. The air from the duct 41 is controlled on the temperature and the air volume by a controller 43. Cutting is performed by a Gebel blade as a rotary shearing blade 46. A distance up to a cutting position by the rotary shearing blade 46 from a heating position P1 by the hot air, is set to 10 mm to 200 mm. Since there is no sticking of cut powder and chips in a product part 31b of the provided film 31, the edge of the product part 31b is formed as the excellent cutting processing part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for cutting a polymer film, and more particularly to a method for cutting a polymer film for use in the optical field such as a polarizing plate, an optical compensation film, and a liquid crystal display device.

  Optical applications include, for example, polarizing plates, optical compensation films, liquid crystal display devices, and the like. For polymer films used for these, productivity is improved, that is, film formation speed is increased. This is due to the growing demand for optical products and the strong demand for cost reduction. Further, in the optical applications as described above, there is a great demand for high functionality and multi-functionality, and in order to meet this demand, the polymer film is made thinner.

  Many of the various polymer films used for optical applications are generally obtained by casting a dope on a support using a casting die, peeling the dope from the support and drying it. This is a typical film manufacturing method called a solution casting method. The obtained film is cut into a predetermined size. This cutting may be, for example, cutting before winding on a winding shaft or the like in order to make the film after drying have a predetermined width, and further, the wound long film becomes a sheet shape. As described above, there is a case of cutting to a predetermined length. Further, there is a case where the ear portion is cut or cut into a sheet or the like after the coating liquid is applied to the long film that has been wound or wound.

  In this cutting process, if the film has poor cutting properties, cracks are generated on the cut surface, chips and chips (hereinafter sometimes referred to as cutting chips) are generated, and this is caused by static electricity or wind. May adhere to the cutting blade or film product part, etc., and cause conveyance failure or product failure. In addition, when the film has poor cutting properties, a cutting portion (hereinafter referred to as a cutting processing portion) serving as a film product edge may be deformed or the product portion may be cut.

  In the optical field as described above, it is necessary to perform a stretching process according to the application, and the polymer film thus stretched becomes brittle by stretching, so that the cutting property is reduced. Therefore, there is a problem that the occurrence frequency of chips and cutting becomes high.

Accordingly, various proposals have been made to improve the cutting performance. For example, the cutting part of a polymer film is locally heated and cut with a cutter in a state of Tg (polymer glass transition temperature) ° C. to (Tg + 100) ° C. (see, for example, Patent Document 1) or cutting A method of cutting while maintaining the residual volatile content and temperature in a predetermined range (for example, see Patent Document 2) has been proposed. And according to patent document 2, while making a residual volatile content into 1 to 15%, it is supposed that it is more preferable to make the temperature of a cut part into 60 to Tg (glass transition temperature of a polymer).
Japanese Unexamined Patent Publication No. 1-281896 (2nd page, FIG. 2) Japanese Patent Laid-Open No. 9-85680 (page 3-4, FIG. 1)

  However, none of the above methods can completely suppress the generation of chips and the like and the deformation of the cutting processing unit as described above. For example, if the polymer film is heated to Tg regardless of the solvent content, it will soften and become easy to cut, but the cutting part and its vicinity will be deformed in a wave shape, and earring will occur. There are problems such as. FIG. 7 shows a cross-sectional view of the ear stand 103 generated in the cutting processing unit 102 of the film 101. The ear stand 103 is configured such that when a cutting blade such as a cutter cuts the film 101 and leaves the film 101, the cutting processing unit 102 of the film 101 is in close contact with the cutting blade because, for example, the film 101 is too soft and excessively viscous. It is generated by being pulled as it is.

  This invention is made | formed in view of the said subject, The cutting method which improves the cutting property of a polymer film, suppresses generation | occurrence | production of the chips and chips by cutting | disconnection, and can obtain a favorable cutting process part. The purpose is to provide.

  In the present invention, in the method of cutting a polymer film with a cutting blade, when the glass transition temperature of the polymer is Tg (unit: ° C) and the temperature of the polymer film at the time of cutting is T (unit: ° C), Tg It is characterized by satisfying −90 ≦ T ≦ Tg−30.

  The polymer film is preferably continuously conveyed. In this case, the polymer film is heated by a heating means before cutting, and the distance between the heating position and the cutting position is set to 10 mm or more and 200 mm or less. preferable. Moreover, it is preferable to heat a polymer film from both surfaces with the said heating means.

  The heating of the polymer film is preferably performed by blowing warm air or irradiating light, and more preferably by using an incandescent lamp or an infrared heater. The cutting blade is preferably a rotary shear blade or a rotary leather blade.

  By the method for cutting a polymer film of the present invention, the cutting property of the polymer film can be improved, the generation of chips and chips etc. due to cutting can be suppressed, and a good cutting treatment part can be obtained. Furthermore, the effect can be obtained even with a laminated film having a coating layer or the like, and the film can be cut in a reusable state.

  The present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiments. FIG. 1 is a schematic view of a film production facility embodying the present invention. The solution casting apparatus 10 includes a reserve tank 12 to which the dope 11 is supplied, a liquid feeding pump 15, a casting device 16, a tenter device 17, a roller drying device 21, a cutting device 22, and a winding device. 23. The casting apparatus 16 includes a casting die 25 and a band 27 as a support that is conveyed while being supported by a backup roller 26. Further, a stripping roller 32 for stripping the film 31 from the band 27 is provided downstream of the band 27. In order to stably introduce the film 31 into the tenter device 17, the number of rollers 33 is increased or decreased as necessary, downstream of the peeling roller 32. Further, these rollers 32 and 33 are appropriately determined as to whether they are driven or not driven.

  The dope 11 is sent from the reserve tank 12 to the casting die 25 by the liquid feed pump 15. The casting die 25 and the dope 11 are cast on the band 27. The band 27 is continuously conveyed by a backup roller 26 that is driven to rotate, whereby the dope 11 is continuously cast. The cast dope is peeled off as a film 31 when it has self-supporting property on the band 27. This stripping may be performed continuously by the rotation of this roller 32 around the stripping roller 32 located at the uppermost stream in the crossing section 34, or by other stripping means, etc. It may be performed continuously by applying tension from the downstream side of the band 27 in the transport direction of the film 31. The film 31 thus peeled off is sent to the tenter device 17 through the crossing section 34.

  In the tenter device 17, the film 31 is dried while being regulated in width and being stretched. In the tenter device 17, a tenter clip (not shown) travels according to a tenter track (not shown) while holding both side ends of the film 31, and the film 31 is conveyed by the travel of the tenter clip. A pin clip or the like may be used instead of the tenter clip. The tenter clip is automatically controlled to be opened and closed by a controller (not shown), and the film 31 is held and released by this opening and closing. The tenter clip holding the film 31 travels inside the tenter device 17 and is automatically controlled to release the holding portion and release the holding of the film 31 when reaching a predetermined holding release point near the exit.

  The film 31 of the tenter device 17 is sent to a roller drying device 21 which is a next process by a supporting or conveying roller 32, and is sufficiently dried while being supported or conveyed by a plurality of rollers 21a, and then a cutting device. The both end portions are cut and removed by 22. The cutting device 22 will be described in detail later, and a part of the illustration is omitted in FIG. The central part remaining after cutting is wound up as a product by the winding device 23.

  Next, the cutting method will be described with reference to FIGS. 2 is a side view showing the cutting device, and FIG. 3 is a cross-sectional view taken along line XX in FIG. The cutting device 22 includes a duct 41 serving as a heating unit, a blower 42, and a controller 43, and a rotary shear blade (Gebel-type cutting blade) 46 serving as a cutting unit. In the rotary shear blade 46, an outer blade 46a and an inner blade 46b are paired, and a controller (not shown) for controlling the movement of the outer blade and the inner blades 46a, 46b in the A1, 2 direction is connected. . The duct 41 is provided on both sides of the film 31. Here, in order to avoid complexity in FIG. 3, the illustration of the duct 41 is omitted. The duct 41 has a slit (not shown) for supplying air, and this slit is provided facing the film side. The slit is provided with a plurality of opening / closing lids in the width direction of the film 31, and each of them can be opened / closed independently. Thereby, while being able to supply only to the predetermined location of the film 31 in driving | running | working, it can respond with respect to the film 31 of various widths.

  In the present embodiment, the duct 41 is provided to heat at least cutting target portions at both side ends of the film 31, and sends the wind sent from the blower 42 to a predetermined position of the film 31. The controller 43 is connected to the blower 42 and controls the temperature and air volume of the air supplied to the duct 41. Thereby, the air supply from the duct 41 to the film 31 is adjusted so that the temperature and the air volume have predetermined values.

  Here, the condition of the air supply is set so that the temperature of the film becomes a predetermined value. At this time, the conveyance speed and the distance between the air supply position and the cutting position are taken into consideration. In the present invention, the air supply condition is set so that the temperature T1 at the time of cutting the film 31 becomes (Tg−90) ° C. or higher and (Tg−30) ° C. or lower by the air supply from the duct 41. The Tg is the glass transition temperature of the polymer forming the film 31, and the polymer exhibits rubber-like elasticity when higher than this value. When the temperature T at the time of cutting the film is lower than (Tg−90) ° C., the polymer is not elastic enough to be torn from the cut portion, and chips and chips are generated. On the other hand, if the temperature T at the time of cutting the film is higher than (Tg-30) ° C., the film may be excessively soft and may cause earing in the cut portion or may not be cut. Here, the temperature T1 is a temperature at a cutting target position, and the entire film may not be in the temperature range. Regarding the conditions of the temperature of the supply air and the air volume, it is preferable to consider thermal conductivity, specific heat, etc. when the film 31 is thicker than 100 μm, for example, but when the thickness is 100 μm or less, particularly about 80 μm or less. Need not be considered.

  As for the rotary shear blade 46, at the start of cutting, the outer blade 46a moves in the A2 direction, the inner blade 46b moves in the A1 direction, and is set at a predetermined position for cutting. When cutting is stopped and finished, the outer blade 46a moves in the A1 direction and the inner blade 46b moves in the A2 direction. And the outer blade 46a and the inner blade 46b rotate centering on each rotating shaft 46c, 46d. Thereby, the running film 31 is continuously cut. Then, the product 31a is taken up by the take-up device, and the cut / removal part 31b is collected for reuse. The rotary shear blade 46 is set outside the film 31 with the outer blade 46a and the outer blade 46b overlapping in advance as shown in FIG. 3, and enters from the side edge of the film 31 at the time of cutting. A predetermined position may be started to be cut.

  In practice, it is difficult to measure the temperature at the time of cutting. In this embodiment, an infrared temperature sensor 47 is provided at a position immediately before reaching the rotary blade 46, and this detected temperature is regarded as the temperature at the time of cutting. ing. Then, the infrared temperature sensor 47 and the controller 43 may be connected. In that case, the temperature detected by the infrared temperature sensor 47 is transmitted to the controller 43, and the controller 43 can set the air supply condition based on the detected temperature.

  Thus, in the present invention, before cutting the film, it is heated to a predetermined temperature, and the temperature at the time of heating is set to (Tg-90) ° C. or higher and (Tg-30) ° C. or lower, whereby chips and chips are cut. There is no generation | occurrence | production of waste and a favorable cutting process part can be obtained. That is, for example, in the case of a cellulose triacetate film, since the glass transition temperature is 130 ° C., the cutting property can be improved only by heating to about 50 ° C.

  And the distance from the position of the film 31 heated by the duct 41 to the position cut | disconnected by the rotary shear blade 46 is 10 mm or more and 200 mm or less. If this distance is shorter than 10 mm, the rotary shear blade 46 and the entire cutting device 22 are heated, so that there is a problem that the cutting performance is deteriorated and the life of the rotary shear blade 46 is shortened. If the distance is longer than 200 mm, there is a problem that the temperature of the film 31 changes until it is cut and the predetermined temperature is not reached and good cutting cannot be performed. This distance is more preferably 10 mm or more and 100 mm or less, and more preferably 10 mm or more and 50 mm or less. Here, the position of the film 31 heated by the duct 41 is defined as a downstream limit where the wind of the duct 41 is hit, and is indicated by reference sign P1. In the present invention, this distance is set so that the heated film 31 does not fall below a predetermined temperature in the range of (Tg−90) ° C. or higher and (Tg−30) ° C. or lower during cutting, or As described above, the target temperature for heating is set according to the distance and the conveyance speed. That is, the heating target temperature is determined by the balance between the distance and the conveyance speed.

  In the present invention, the temperature of the film is adjusted to control mechanical properties such as the elongation at break and elastic modulus of the polymer. That is, in the present invention, the temperature dependence of mechanical properties such as the elongation at break and elastic modulus of the polymer is used as a setting scale for the temperature at the time of cutting. Therefore, in the present invention, the polymer forming the film is not necessarily limited to those having a glass transition temperature Tg. For example, even if the polymer originally has a glass transition temperature Tg, the glass transition temperature may not be detected depending on the polymerization state, polymerization degree, molecular arrangement, etc., or the glass transition temperature depends on whether it is crystalline or not. With or without. In addition, when manufacturing the film, various additives may be added to the film as necessary, or various treatments such as stretching may be performed, and the polymer that is the main component of the film is the same. Even so, the mechanical strength as described above when used as a film may show different temperature dependence. In such a case, temperature dependency data such as the elongation at break and elastic modulus of the polymer of the film to be cut can be taken in advance, and the heating temperature by the duct 41 can be determined based on the data.

  Here, the results of the study by the present inventors that have led to obtaining the preferred cutting temperature will be described. The polymer was cellulose triacetate (TAC), and temperature dependency data were collected for its elongation at break and elastic modulus. The elongation at break means the rate of elongation until the film is tensioned to break, and the distance between any two points before applying tension in a predetermined direction is x1, after applying tension (at the time of breaking) ) Is a value (unit:%) obtained by {(x2-x1) / x1} × 100, where x2 is the distance between the two points. These measurements can be made with various commercially available tensile testers (trade name: Tensilon, etc.). As already explained, depending on the film processing method such as the stretching method and the kind of additives included, the elongation at break and the elastic modulus at a predetermined temperature are different, but in the case of a thermoplastic polymer film In general, in a temperature range of approximately 20 ° C. to 140 ° C., as the temperature increases, the elongation at break tends to increase and the elastic modulus tends to decrease, and it becomes soft and easily stretched.

  In the case of TAC, the same tendency is shown, and the film has an elongation at break of approximately 40 ± 10 (%) and an elastic modulus of approximately 3 ± 1.5 (GPa). When temperature is set, cutting is carried out satisfactorily, and the temperature range becomes (Tg-90) ° C. or higher and (Tg-30) ° C. or lower. By setting at least the surface temperature of the film within this temperature range, the elongation at break and the elastic modulus suitable for cutting can be controlled. At a film temperature lower than (Tg−90) ° C., the modulus of elasticity is too large and the elongation at break is too small, the film is hard and brittle, and therefore, the cutting property is deteriorated and cracks are formed on the cut surface. Or generation of fiber scraps from cracks is observed. On the other hand, at a film temperature higher than (Tg-30) ° C., the elongation at break is too large and the elastic modulus is too small, and the film is soft and easy to stretch. Will be deformed. In this embodiment, the evaluation of the cutting performance is performed by observing the shape of the cutting processing section including the cut surface and the amount of cutting waste on the cut surface, and the shape observation is performed by an electron microscope. .

  TAC is a polymer having a glass transition temperature of 130 ° C. As described above, the target temperature range for heating can be determined by mechanical properties such as viscoelasticity without using the glass transition temperature Tg as a reference. Therefore, for example, the heating target temperature is set for a polymer that does not have a glass transition temperature, a polymer that has an extremely low glass transition temperature and a thermal deformation temperature that is higher than the glass transition temperature, and a polymer that does not have a glass transition temperature. There are cases where it is possible.

  In the present embodiment, the air supply port of the duct 41 is a slit that is elongated in the width direction of the film 31, but is not limited thereto. For example, a method of supplying air from a large number of holes as a perforated plate may be used as long as air can be supplied to a predetermined portion of the film 31 under predetermined conditions.

  In this embodiment, the duct 41 is provided on both sides of the film and both sides are heated at the same time. However, one side may be heated first and then the other side may be heated. Moreover, as long as a cutting process part can be heated to predetermined temperature, the heating from any one side may be sufficient, and this invention is not limited to double-sided heating. However, the heat treatment time is preferably short in consideration of the modification of the film 31, and more preferably, the heating is performed from both sides.

  In addition, by providing a suction means for sucking foreign matter in the vicinity of the film at the cutting position or in the vicinity of the rotary shear blade 46 that is a cutting portion, chips that may be generated very slightly, surrounding dust, etc. Can also be aspirated.

  In the present embodiment, the heating method is not limited to heated air supply. For example, as shown in FIG. 4, a light source such as an incandescent lamp 51 may be used instead of the duct 41 and the blower 42 (both refer to FIG. 2), and the film 31 may be heated by energy from the light source. Further, as shown in FIG. 5, the film 31 may be heated by replacing the infrared heater 56 and the like with a duct and a blower. Such a lamp light source, an infrared heater, and the like are effective in that they do not cause fluttering of the film due to air supply, and that dust around the film does not adhere to the film. Moreover, these methods may be employed alone or in combination. As described above, the present invention is not limited to the heating method. However, due to operability, cost, etc., at least one of the above-described methods of blowing warm air and irradiating energy from a lamp light source or an infrared heater is used. preferable.

  FIG. 6 is a front view showing a partial cross section of a cutting processing unit as another embodiment of the present invention. In this embodiment, a score type cutter 61 as a rotary leather blade is used instead of the rotary shear blade of FIG. The score type cutter 61 includes a roller 62 and a rotary blade 63, and the roller 62 rotates while supporting the film 31 that is continuously conveyed. The roller 62 is provided with a groove 62a on the outer peripheral surface of the side end in the longitudinal direction, and the cut target portion of the film 31 runs on the side end where the groove 62a is formed. The rotary cutter 63 is formed in a disk shape, and a blade 63a is formed on the circumference thereof, and rotates around the rotary shaft 63b. The film 31 is conveyed so as to be sandwiched between the rotary cutter 63 and the roller 62, and the film 31 is continuously cut according to the rotational speed of the roller while the blade 63a enters the groove 62a of the roller 62. The rotational speed of the rotary cutter unit 63 may not be the same as the rotational speed of the roller 62. And after heating the film 31, if it cut | disconnects by this method, a favorable cutting process part can be obtained, without generating a chip and a chip. The blade 63a of the rotary blade 63 may be either a single blade or a double blade. However, since the stress on the film 31 is equalized on both sides of the blade and the cutting processing portions on both sides become better, FIG. What has a double blade as shown in FIG. 6 is more preferable.

  In the present invention, the cutting method is not limited to the above-described cutting with the rotary blade and the cutting with the rotary leather blade, and various known cutting methods can be adopted. Cutting with a rotary leather blade represented by a type cutter is particularly preferred.

  In the present invention, the solvent content of the film 31 at the time of cutting is not particularly limited. Therefore, although it cut | disconnects just before winding in this embodiment, it can cut | disconnect in the arbitrary positions after peeling from the band 27 (refer FIG. 1). However, when it contains a solvent, the temperature lower than the boiling point of the solvent must be the upper limit temperature for heating the film 31. When the solvent is a mixture, the lowest boiling point among the boiling points of each solvent component is the upper limit. This is because when a film containing a solvent is heated, the compound as a solvent component rapidly evaporates from the inside of the film due to the heating, and bubbles, cracks, blisters, etc. are generated in the film 31. Further, when the film 31 contains various additives such as a plasticizer and an ultraviolet absorber, it is necessary to set the heating temperature according to their thermal characteristics and volatility, and in particular, a solvent is contained. It is preferable to take volatilization behavior data in advance and set the heating temperature. Thereby, the suppression effect of a bubble, a swelling, etc. increases.

  When cutting in a state containing a solvent, it is preferable to set the heating temperature according to the viscoelasticity data in the content ratio. This is because the state containing the solvent has a greater difference in mechanical properties from before and after heating than when no solvent is contained. In that sense, the solvent content is preferably low, and the upper limit is approximately 25%, more preferably the upper limit is 20%. Here, the solvent content is defined as {(x−) when the weight of the sample film at the time of sampling is x (unit; g) and the weight after the sample film is dried is y (unit; g). y) / y} × 100. When the solvent content is higher than 25%, the occurrence frequency of bubbles and blisters is high.

  Moreover, when the film containing a solvent is cut, the present invention is not limited to the solvent, and various solvents can be used. For example, in addition to various halogenated hydrocarbons, alcohols, ethers, esters, ketones and the like can be used alone or in combination. Further, when various additives are appropriately contained in the film, the additive is not limited, and examples thereof include a plasticizer, an ultraviolet absorber, a dye, an optically anisotropic compound, and a matting agent.

  In addition, the present invention is particularly effective when cutting a film of 20 μm to 200 μm, and such a film generally increases adhesion of chips and the like due to generation of static electricity as the conveyance speed is increased. In this invention, since generation | occurrence | production of the chip and chip itself is suppressed, it is effective. The present invention is most effective when a film of 40 μm to 100 μm is cut.

Moreover, in this embodiment, although the film to cut | disconnect is made into the TAC film, it is not limited to this. Moreover, it is not limited to the film manufactured by the solution casting method like this embodiment. That is, the same effect can be obtained even with a polymer film prepared by a melt extrusion method or the like.

  Examples of the polymer from which the effect of the cut state of the film can be obtained according to the present invention include various cellulose acylates including TAC in the present embodiment, polyethylene terephthalate (PET), polyethylene-2,6-naphthalate (PEN), and the like. And various polyolefins such as polyethylene (PE), polystyrene, polyvinyl chloride (PVC), polyvinylidene chloride, polycarbonate (PC), polyamide (PA), polyimide (PI) and the like. In the case of polyimide, a solution of the polyamic acid that is the precursor is cast, and this is heated and dried to remove the solvent and cross-link to form a polyimide film. May be before or after complete crosslinking. Of these, TAC is most effective.

  The details of cellulose acylate are described in paragraphs [0140] to [0195] of Japanese Patent Application No. 2004-264464. These descriptions are also applicable to the present invention. The same applies to additives such as solvents and plasticizers, deterioration inhibitors, UV absorbers (UV agents), optical anisotropy control agents, retardation control agents, dyes, matting agents, release agents, release accelerators, etc. The details are described in paragraphs [0196] to [0516] of Japanese Patent Application No. 2004-264464.

  Moreover, although this invention is set as the cutting method of a film, it is applicable also to the cutting | disconnection of polymer molded articles other than a film. The polymer molded product other than the film means, for example, fibers, tapes, hollow fibers and the like, and the cutting method of the present invention can be applied to these cuttings.

  Furthermore, it is effective not only when the film has a single layer structure but also when it has a laminated structure. In the case of a laminated structure, a laminated film using a sequential casting method or a co-casting method is exemplified. However, when the film having such a laminated structure is cut, the film is cut with the solvent removed. This is to prevent an increase in the bonding force between the solvent component and the polymer in any layer when heated to control mechanical properties such as viscoelasticity.

  More specific examples of the laminated structure include a polarizing plate and an optical compensation film. In each of these layers, each layer has a function, and a plurality of polymers are stacked as a thin film. Even if it is these laminated | multilayer films, this invention does not generate | occur | produce chips and chips, but can obtain a favorable cutting process part. Thereby, the laminated film obtained by the cutting method of the present invention is cut without excessively increasing the bonding force of the polymer of each layer, so that each layer can be separated again by a predetermined processing method and reused. Become.

  When cutting a film having a laminated structure, it is preferable to set the temperature by considering the lowest glass transition temperature among the polymers forming each layer of the film as Tg in the above temperature setting, and heat the film. Further, when both a polymer having a glass transition temperature and a polymer having no glass transition temperature are laminated, the temperature considered as Tg in the above temperature setting due to the thermal deformation temperature and the melting point in addition to the glass transition temperature. To select the heating temperature. Alternatively, in this case, viscoelasticity data of each polymer is compared, and the heating temperature may be determined according to this data.

  In addition, from the [0517] paragraph of Japanese Patent Application No. 2004-264464 about the raw material in the solution casting method which obtains a TAC film, the raw material, the additive dissolution method and addition method, the filtration method, and the dope production methods such as defoaming [0616] The paragraph is detailed. These descriptions are also applicable to the present invention.

  From casting die, decompression chamber, support structure, co-casting, peeling method, stretching, drying conditions for each process, handling method, curl, winding method after flatness correction, solvent recovery method, film recovery method The details are described in paragraphs [0617] to [0889] of Japanese Patent Application No. 2004-264464. These descriptions are also applicable to the present invention.

[Performance / Measurement method]
(Curl degree / thickness)
The performance of the wound cellulose acylate film and the measuring method thereof are described in paragraphs [0112] to [0139] of Japanese Patent Application No. 2004-264464. These are also applicable to the present invention.

[surface treatment]
It is preferable that at least one surface of the cellulose acylate film is surface-treated. The surface treatment is preferably at least one of vacuum glow discharge treatment, atmospheric pressure plasma discharge treatment, ultraviolet irradiation treatment, corona discharge treatment, flame treatment, acid treatment or alkali treatment.

[Functional layer]
(Antistatic, hardened layer, antireflection, easy adhesion, antiglare)
At least one surface of the cellulose acylate film may be undercoated.

  Furthermore, it is preferable to use the cellulose acylate film as a base film as a functional material provided with another functional layer. The functional layer is preferably provided with at least one layer selected from an antistatic layer, a cured resin layer, an antireflection layer, an easy adhesion layer, an antiglare layer and an optical compensation layer.

  A method for applying a surface-treated functional layer for realizing various functions and properties on a cellulose acylate film is described in Japanese Patent Application No. 2004-264464, from [0890] paragraph to [1087] paragraph. It is included. These are also applicable to the present invention.

(Use)
The cellulose acylate film is particularly useful as a polarizing plate protective film. Usually, two polarizing plates each having a cellulose acylate film bonded to a polarizer are bonded to a liquid crystal layer to produce a liquid crystal display device. However, the arrangement of the liquid crystal layer and the polarizing plate is not limited, and various known arrangements can be employed. Japanese Patent Application No. 2004-264464 describes in detail TN type, STN type, VA type, OCB type, reflection type, and other examples of liquid crystal display devices. This method can also be applied to the present invention. The application also describes a cellulose acylate film provided with an optically anisotropic layer and a cellulose acylate film provided with antireflection and antiglare functions. Furthermore, the use as an optical compensation film is also described as a biaxial cellulose acylate film imparting moderate optical performance. This can also be used as a polarizing plate protective film. These descriptions are also applicable to the present invention. Details are described in paragraphs [1088] to [1265] of Japanese Patent Application No. 2004-264464.

  Moreover, the cellulose triacetate film (TAC film) excellent in an optical characteristic can be obtained with the manufacturing method of this invention. The TAC film can be used as a polarizing plate protective film or a base film for a photographic photosensitive material. Furthermore, it can also be used as an optical compensation film for improving the viewing angle dependency of a liquid crystal display device for television applications. In particular, it is effective for applications that also serve as a protective film for a polarizing plate. Therefore, it is used not only for the conventional TN mode but also for the IPS mode, OCB mode, VA mode, and the like. Moreover, you may comprise a polarizing plate using the said film for polarizing plate protective films.

[Experiment 1]
Next, examples of the present invention will be described. The film was manufactured using the solution casting apparatus 10. In the following description, the blending and adjusting method for preparing the polymer solution (dope) will be described first, then the film production method, the evaluation of the properties of the obtained film and the results will be described. The cutting conditions by the cutting device 22 relating to the method will be described.
[Dope composition]
Cellulose triacetate (substitution degree 2.84, viscosity average polymerization degree 306, water content 0.2 mass%, viscosity 6 mass% in dichloromethane solution 315 mPa · s, average particle diameter 1.5 mm with standard deviation 0.5 mm Some powder) 100 parts by mass dichloromethane (first solvent) 320 parts by mass methanol (second solvent) 83 parts by mass 1-butanol (third solvent) 3 parts by mass optical property adjusting agent 1.0 part by mass UV agent a: 2 (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole 0.7 parts by mass UV agent b: 2 (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) -5-chlorobenzotriazole 0.3 parts by mass of citric acid ester mixture (citric acid, citric acid monoethyl ester, citric acid diethyl ester, citric acid triethyl ester Mixture) 0.006 parts by weight fine particles (silicon dioxide (particle size 15 nm), Mohs hardness: about 7) 0.05 part by weight dye (Dye example of -115 (I-4)) 0.0005 part by weight

[Cellulose triacetate]
The cellulose triacetate used here has a residual acetic acid content of 0.1% by mass or less, a Ca content of 58 ppm, a Mg content of 42 ppm, a Fe content of 0.5 ppm, and free acetic acid of 40 ppm. It contained 15 ppm of sulfate ions. The degree of substitution of the 6-position acetyl group was 0.91, 32.5% of the total acetyl. Moreover, the acetone extraction part which extracted this TAC with acetone was 8 mass%, and the weight average molecular weight / number average molecular weight ratio was 2.5. The obtained TAC has a yellow index of 1.7, a haze of 0.08, a transparency of 93.5%, a Tg (glass transition point; measured by DSC) of 160 ° C., and a crystallization calorific value of It was 6.4 J / g. This TAC is synthesized using cellulose collected from cotton as a raw material. In the following description, this is called cotton raw material TAC.

(1-1) Dope preparation A dope was prepared using a dope preparation device. In a 4000 L stainless steel dissolution tank having a stirring blade, the plurality of solvents were mixed and stirred well to obtain a mixed solvent. In addition, all the solvents used that the water content is 0.5 mass% or less. Next, TAC powder (flaked powder) was gradually added from the hopper of the dissolution tank. The TAC powder was put into a dissolution tank and dispersed under predetermined conditions for 30 minutes by a dissolver type eccentric stirrer 21 equipped with an anchor blade 19 on a rotating shaft. The temperature at the start of dispersion was 25 ° C., and the final temperature reached 48 ° C. Further, an additive solution prepared in advance was adjusted from the additive tank to the dissolution tank by adjusting the amount of liquid fed with a valve so that the total amount was 2000 kg. After the dispersion of the additive solution was completed, high-speed stirring was stopped, and the anchor blade 19 was further stirred for 100 minutes at a predetermined peripheral speed to swell the TAC flakes to obtain a swelling liquid. The tank was pressurized to 0.12 MPa with nitrogen gas until the end of swelling. The inside of the dissolution tank at this time was kept in a state where there was no problem in terms of explosion prevention because the oxygen concentration was less than 2 vol%. The amount of water in the swelling liquid was 0.3% by mass.

(1-2) Dissolution / filtration The swelling liquid was fed from the dissolution tank to the jacketed pipe using a pump. The swelling liquid was heated to 50 ° C. with a jacketed pipe, and further heated to 90 ° C. under a pressure of 2 MPa to completely dissolve. The heating time at this time was 15 minutes. Next, the temperature of the dissolved liquid was lowered to 36 ° C. with a temperature controller, and the dope (hereinafter referred to as pre-concentration dope) was obtained by passing through a filtration device equipped with a filter medium having a nominal pore diameter of 8 μm. At this time, the primary pressure in the filtration device was 1.5 MPa, and the secondary pressure was 1.2 MPa. As the filter, housing, and piping exposed to a high temperature, those having a jacket made of Hastelloy alloy having excellent corrosion resistance and circulating a heat transfer medium for heat insulation heating were used.

(1-3) Concentration / Filtration / Defoaming / Additive The dope before concentration thus obtained is flash-evaporated in a flash apparatus at 80 ° C. and normal pressure, and the evaporated solvent is condensed in a condenser. And recovered. The solid concentration of the dope after flashing was 21.8% by mass. The condensed solvent was recovered by a recovery device to be reused as a dope preparation solvent, regenerated by a regeneration device, and then sent to a solvent tank. Distillation and dehydration are performed in the recovery device and the regeneration device. The flash tank of the flash device was provided with a stirrer equipped with an anchor blade on the stirring shaft and rotated at a predetermined rotational peripheral speed to stir the flashed dope to perform defoaming. The temperature of the dope in this flash tank was 25 ° C., and the average residence time of the dope in the tank was 50 minutes. The shear viscosity measured at 25 ° C. after collecting this dope was 450 Pa · s at a shear rate of 10 (sec −1).

  Next, bubbles were removed by irradiating the dope with weak ultrasonic waves. Thereafter, the filter was passed through the pump while being pressurized to 1.5 MPa using a pump. In the filtration apparatus, first, a sintered fiber metal filter having a nominal pore diameter of 10 μm was passed, and then a sintered fiber filter having a same pore diameter of 10 μm was passed. Respective primary pressures were 1.5 MPa and 1.2 MPa, and secondary pressures were 1.0 MPa and 0.8 MPa. The dope temperature after filtration was adjusted to 36 ° C., and the dope 11 was fed into a 2000 L stainless steel stock tank and stored therein. The stock tank has a stirrer provided with an anchor blade on the central axis, and the dope was stirred by the stirrer. In addition, no problem such as corrosion occurred at all in the wetted part of the dope from the dope before concentration to the preparation of the dope 11.

  Moreover, the mixed solvent A of 86.5 mass parts of dichloromethane, 13 mass parts of acetone, and 0.5 mass part of 1-butanol was produced.

(1-4) Discharge / immediate addition / casting / bead depressurization A film was produced using the solution casting apparatus 10 shown in FIG. The dope 11 in the reserve tank 12 was sent to the filtration device by the high precision gear pump 15. This pump 15 has a function of increasing the pressure on the primary side of the pump 15 and sends the liquid by performing feedback control on the upstream side of the pump 15 with an inverter motor so that the pressure on the primary side becomes 0.8 MPa. . The pump 15 has a volume efficiency of 99.2% and a discharge rate variation rate of 0.5% or less. The discharge pressure was 1.5 MPa. Then, the dope 11 that passed through the filtration device was fed to the casting die 31.

  The casting die 31 was cast by adjusting the flow rate of the dope 11 at the discharge port of the die 31 so that the width of the casting die 31 was 1.8 m and the thickness of the dried film 31 was 92 μm. The casting width of the dope 11 from the discharge port of the die 31 was 1700 mm. In order to adjust the temperature of the dope 11 to 36 ° C., a jacket (not shown) is provided on the casting die 31 and the inlet temperature of the heat transfer medium supplied into the jacket is set to 36 ° C.

  The casting die 31 and the piping were all kept at 36 ° C. during operation. The casting die 31 is a coat hanger type die. And as this die | dye 31, the thickness adjustment bolt was provided in 20 mm pitch, and what equipped the automatic thickness adjustment mechanism by a heat bolt was used. This heat bolt can also set a profile according to the amount of liquid delivered by the pump 15 by a preset program, and is fed back by an adjustment program based on the profile of an infrared thickness meter (not shown) installed in the solution casting apparatus 10. The thing which has the performance which can also be controlled was used. In the film excluding the casting side end portion of 20 mm, the difference in thickness between any two points separated by 50 mm was within 1 μm, and the thickness variation in the width direction was adjusted to 3 μm / m or less. The overall thickness was adjusted to ± 1.5% or less.

  In addition, a decompression chamber for decompressing this portion was installed on the primary side of the casting die 31. The degree of decompression of the decompression chamber is adjusted so that a pressure difference of 1 Pa to 5000 Pa is generated before and after the casting bead, and this adjustment is made according to the casting speed. At that time, the pressure difference on both sides of the bead was set so that the length of the bead became a predetermined value. Further, the decompression chamber was provided with a mechanism that can be set to a temperature higher than the condensation temperature of the gas around the casting part. Labyrinth packings (not shown) were provided on the front and back sides of the beads at the die discharge port, and openings were provided at both ends of the die discharge port. Further, the die 31 is provided with an edge suction device (not shown) for adjusting the disturbance of both edges of the casting bead.

(1-5) Casting Die The material of the casting die 31 is a material precipitation hardening type stainless steel having a thermal expansion coefficient of 2 × 10 −5 (° C. −1) or less. This is a material that has almost the same corrosion resistance as that of SUS316 in the forced corrosion test with an aqueous electrolyte solution, and it can be pitted at the gas-liquid interface even if it is immersed in a mixed solution of dichloromethane, methanol, and water for 3 months. Corrosion resistance that does not cause (perforation). The finishing accuracy of the wetted surface of the casting die 31 was 1 μm or less in terms of surface roughness, the straightness was 1 μm / m or less in any direction, and the slit clearance was adjusted to 1.5 mm. The corner portion of the liquid contact portion at the tip of the lip of the die 31 is processed so that R is 50 μm or less over the entire width of the slit. The shear rate inside the die was in the range of 1 (1 / sec) to 5000 (1 / sec). Further, a WC (tungsten carbide) coating was performed on the lip end of the casting die 31 by a thermal spraying method to provide a cured film.

  Furthermore, in order to prevent the dope 11 flowing out from being locally dried and solidified at the discharge port of the casting die 31, the mixed solvent A for solubilizing the dope 11 is provided on both side ends of the casting bead. Each 0.5 ml / min was supplied to the interface with the discharge port. The pulsation rate of the pump supplying the mixed solvent A was 5% or less. In addition, the pressure on the back side of the bead was reduced by 150 Pa from the front side by the decompression chamber. In addition, a jacket (not shown) was attached in order to keep the internal temperature of the decompression chamber constant at a predetermined temperature. A heat transfer medium adjusted to 35 ° C. was supplied into the jacket. The edge suction device can adjust the edge suction air volume so as to be in the range of 1 L / min to 100 L / min, and in the present embodiment, this is in the range of 30 L / min to 40 L / min. Adjusted appropriately.

(1-6) Metal support As the support, a stainless steel endless band having a width of 2.1 m and a length of 70 m was used as the casting band 27. The casting band 27 was polished so that the thickness was 1.5 mm and the surface roughness was 0.05 μm or less. The material is made of SUS316 and has sufficient corrosion resistance and strength. The thickness unevenness of the entire casting band 27 was 0.5% or less. The casting band 27 was conveyed by two backup rollers 32. The relative speed difference between the casting band 27 and the backup roller 32 was adjusted to 0.01 m / min or less so that the tension in the conveying direction of the casting band 27 at that time was a predetermined value. The speed fluctuation of the casting band 27 was 0.5% or less. Further, both end positions of the casting band 27 were detected and controlled so that the meandering in the width direction of one rotation was limited to 1.5 mm or less. Further, the positional fluctuation in the vertical direction between the die lip tip and the casting band 27 immediately below the casting die 31 was set to 200 μm or less. The casting band 27 is installed in a casting chamber (not shown) having wind pressure fluctuation suppressing means (not shown). The dope 11 was cast from the casting die 31 on the casting band 27.

  As the backup roller 32, a roller capable of feeding a heat transfer medium therein was used so that the temperature of the casting band 27 could be adjusted. A 5 ° C. heat transfer medium was passed through the backup roller 32 on the casting die 31 side, and a 40 ° C. heat transfer medium was passed through the other backup roller 36 for drying. The surface temperature of the central part of the casting band 27 immediately before casting was 15 ° C., and the temperature difference between both side ends was 6 ° C. or less. The casting band 27 preferably has no surface defects, has no pinholes of 30 μm or more, has no pinholes of 10 μm to 30 μm / m 2 or less, and has 2 pinholes of less than 10 μm / m 2. The following were used.

(1-7) Casting drying The temperature of the casting chamber was kept at 35 ° C. using temperature control equipment. The casting film formed from the dope 11 cast on the casting band 27 was first fed with drying air flowing parallel to the casting film, and dried. The overall heat transfer coefficient from the dry air to the cast film was 24 kcal / m 2 · hr · ° C. The temperature of the drying air was 135 ° C. on the upstream side of the upper part of the casting band 27 and 140 ° C. on the downstream side. The lower part of the casting band 27 was blown from a blower (not shown) so that the temperature was 65 ° C. The saturation temperature of each drying wind was around -8 ° C. The oxygen concentration in the dry atmosphere on the casting band 27 was kept at 5 vol%. In order to maintain this oxygen concentration at 5 vol%, the air was replaced with nitrogen gas. Further, in order to condense and recover the solvent in the casting chamber, a condenser (condenser) was provided, and its outlet temperature was set to -10 ° C.

  For 5 seconds after casting, the dry air from the wind shield device was prevented from directly hitting the dope 11 and the casting film, and the static pressure fluctuation in the immediate vicinity of the casting die 31 was suppressed to ± 1 Pa or less. When the solvent ratio in the casting film reached 50% by mass on the dry basis, the film was peeled off as the film 31 while being supported from the casting band 27 with a peeling roller. The solvent content on the basis of the dry weight is a value obtained by {(y1-y2) / y2} × 100, where y1 is a film weight at the time of sampling and y2 is a weight after the sampling film is dried. . The stripping tension at this time is controlled to be a predetermined value, and the stripping speed (stripping roller draw) with respect to the speed of the casting band 27 is 100.1% to 110% in order to suppress stripping failure. Adjusted appropriately in range. The surface temperature of the peeled film was 15 ° C. The drying rate on the casting band 27 was 60% by mass on the basis of dry weight reference solvent / min. Met. The solvent gas generated by the drying was condensed and liquefied with a -10 ° C. condenser and recovered with a recovery device (not shown). The recovered solvent was adjusted so that the water content was 0.5% or less. The drying air from which the solvent has been removed is heated again and reused as drying air. The film 31 was conveyed through a roller and sent to the tenter device 17. At the time of this conveyance, 40 degreeC dry air was sent with respect to the film 31 from the air blower (not shown). It should be noted that a predetermined tension was applied to the wet film 66 during conveyance with the roller at the crossing section.

(1-8) Tenter Transport / Drying / Ear Cutting The film 31 sent to the tenter device 17 is transported in the drying zone of the tenter device 17 while being fixed at both ends with clips, and is dried by drying air during this time. The clip was cooled by supplying a heat transfer medium at 20 ° C. The clip in the tenter device 17 was conveyed by a chain, and the speed fluctuation of the sprocket was 0.5% or less. Further, the temperature in the tenter device 17 was set to 140 ° C. The gas composition of the drying air was set to a saturated gas concentration at −10 ° C. The average drying speed in the tenter device 17 was 120% by mass (dry weight reference solvent) / min. The conditions of the drying zone were adjusted so that the residual solvent amount of the film 31 at the outlet of the tenter device 17 was 7% by mass. In the tenter device 17, the film 31 was transported and stretched in the width direction. In addition, when the width | variety of this film 31 before extending | stretching was 100%, it extended | stretched so that the width | variety after extending | stretching might be 103%. The stretching ratio (tenter drive draw) from the peeling roller 32 to the entrance of the tenter device 17 was 102%. The stretching ratio in the tenter device 17 was controlled to be a predetermined value. Further, the ratio of the length from the clip pinching start position to the pinching release position with respect to the length from the tenter inlet to the outlet was 90%. The solvent evaporated in the tenter apparatus 17 was condensed and liquefied at a temperature of −10 ° C. and recovered. A condenser (condenser) was provided for condensation recovery, and the outlet temperature was set to -8 ° C. The condensed solvent was reused after adjusting the water content to 0.5% by mass or less.

  Then, the ears of the film 31 were cut with a cutting device (not shown) similar to the cutting device 22 within 30 seconds from the outlet of the tenter device 17. Note that this ear-cutting will be described in detail later.

(1-9) Post-drying / static elimination The film 31 was dried at high temperature by the roller dryer 21. The roller drying device 21 was divided into four sections, and drying air at 120 ° C., 130 ° C., 130 ° C., and 130 ° C. was supplied from a blower (not shown) from the upstream side. The conveyance tension of the film 31 by the roller 21a was controlled to a predetermined value, and the film 31 was dried for about 10 minutes until the residual solvent amount finally reached 0.3% by mass. The wrap angle (film winding center angle) in the roller 21a was 90 ° and 180 °. The material of the roller 21a was made of aluminum or carbon steel, and hard chrome plating was applied to the surface. The roller 21a has a flat surface shape and a blasted mat. All film position fluctuations due to the rotation of the roller 21a were 50 μm or less. Further, the deflection of the roller 21a after being tensioned was selected to be 0.5 mm or less.

  The solvent gas contained in the drying wind was removed by adsorption using an adsorption / recovery device (not shown). The adsorbent used here was activated carbon, and desorption was performed using dry nitrogen. The recovered solvent was adjusted to a water content of 0.3% by mass or less and reused as a dope preparation solvent. Since the drying air contains solvent gas, plasticizer, UV absorber, and other high-boiling substances, these were removed by a cooler and a pre-adsorber for cooling and removing them, and recycled and used. And adsorption / desorption conditions were set so that VOC (volatile organic compound) in the outdoor exhaust gas was finally 10 ppm or less. Moreover, the solvent amount collect | recovered by a condensation method among all the evaporation solvents was 90 mass%, and most of the remainder was collect | recovered by adsorption collection.

  The dried film 31 was conveyed to a first humidity control chamber (not shown). A drying air of 110 ° C. was supplied to the transition portion between the roller drying device 21 and the first humidity control chamber. Air having a temperature of 50 ° C. and a dew point of 20 ° C. was supplied to the first humidity control chamber. Further, the film 31 was transported to a second humidity control chamber (not shown) for suppressing the curling of the film 31. In the second humidity control chamber, air of 90 ° C. and humidity 70% was directly applied to the film 31.

(1-10) Knurling and winding conditions The film 31 after humidity control was subjected to ear cutting by the cutting device 22 after cooling to 30 ° C. or lower in the cooling chamber. A forced charge removal device (charge removal bar) was installed so that the charged voltage of the film 31 during conveyance was always in the range of -3 kV to +3 kV. Further, knurling was applied to both ends of the film 31 with a knurling roller. The knurling is imparted by embossing from one side of the film 31, the width for imparting the knurling is 10 mm, and the knurling is pushed by a knurling roller so that the height of the irregularities is 12 μm higher than the average thickness of the film 31. The pressure was set.

  Then, the film 31 was conveyed to the winding device 24. The winding device 23 is maintained at an internal temperature of 28 ° C. and a humidity of 70%. Further, an ion wind neutralization device (not shown) was also installed inside the winding device 23 so that the charged voltage of the film 31 was −1.5 kV to +1.5 kV. The product width of the film (thickness 92 μm) 36 thus obtained is 1475 mm. The diameter of the winding roller of the winding device 23 is 169 mm. The tension was controlled so that the tension at the start and end of winding became a predetermined value. The total length of the wound film 31 was 3940 m. The fluctuation range of winding deviation (sometimes referred to as oscillating width) during winding was ± 5 mm, and the winding deviation period with respect to the winding axis was 400 m. Further, the pressing pressure of the press roller with respect to the winding shaft was controlled to be a predetermined value. The temperature of the film 31 at the time of winding was 25 ° C., the water content was 1.4% by mass, and the residual solvent amount was 0.3% by mass. The average drying rate was 20% by mass (dry weight reference solvent) / min throughout the entire process. Moreover, there was no winding looseness and wrinkles, and no winding slip occurred in the impact test at 10G. Moreover, the external appearance of the film roll was also favorable.

  The film roll was stored in a storage rack at 25 ° C. and a relative humidity of 55% (hereinafter referred to as 55% RH) for one month and further examined in the same manner as described above. As a result, no change was observed. Further, no film adhesion was observed in the film roll. In addition, after the film 31 was formed, no casting film residue formed from the dope 11 was observed on the casting band 27 at all.

(1-11) Evaluation and Results Evaluation methods for the samples obtained in the examples are shown below.

(1) Stability of solution The concentrated dope 11 was collected, observed while standing still at 30 ° C., and evaluated in the following four stages of A, B, C, and D.
A: Transparency and liquid uniformity are exhibited even over 20 days.
B: Transparency and liquid uniformity are maintained until lapse of 10 days, but a little white turbidity is observed in 20 days.
C: Transparency and liquid uniformity are observed at the end of liquid preparation, but after one day, it gels and becomes a non-uniform liquid.
D: The liquid is in an opaque and non-uniform liquid state with no swelling / dissolution.

(2) Film surface shape The film 31 was observed visually and the surface shape was evaluated as follows.
A: The film surface is smooth.
B: Although the film surface is smooth, a little foreign material is seen.
C: Weak irregularities are seen on the film surface, and the presence of foreign matter is clearly observed.
D: Unevenness is seen on the film surface, and many foreign matters are seen.

(3) Moisture and heat resistance of the film 1 g of the film 31 was cut as a sample, folded and placed in a 15 ml glass bottle, conditioned at 90 ° C. and 100% RH, and sealed. This was kept at 90 ° C. and removed after 10 days. The state of the film 31 was confirmed visually and the following determinations were made.
A: No particular abnormality is observed B: A slight decomposition odor is observed C: A considerable decomposition odor is recognized D: A change in shape due to decomposition odor and decomposition is observed

  The stability of the dope 11 was A. Further, the obtained film 31 was also excellent in that the film surface was A, the film tear test was 16 g, the film folding test was 71 times, and the heat and moisture resistance was A. The amount of residual acetic acid is less than 0.01% by mass, Ca is less than 0.05% by mass, Mg is less than 0.01% by mass, and the thickness of the cellulose triacetate film is 80 μm ± It was 1.5 μm. This thickness evaluation is performed for each of the front end portion, the middle portion, and the rear end portion in the length direction at both ends and the center portion in the width direction, and the data has an error of 0.2% or less. Was confirmed in advance. In addition, the longitudinal and transverse average heat shrinkage (80 ° C., 90% RH, 48 hours) of the film 31 was −0.1%, and it was confirmed that the film 31 in which heat shrinkage hardly occurs was obtained. Moreover, the residual solvent amount of the film 31 at the exit of the tenter device 17 was 7% by mass, and the solvent gas concentration (LEL value) inside the silo 45 at that time was good at less than 25%.

  The obtained film 31 has a haze of 0.3%, a transparency (transparency) of 92.4%, a slope width of 19.6 nm, a wavelength limit of 392.7 nm, an absorption edge of the absorption wavelength of 374.1 nm, Absorption at 380 nm is 2.0%, in-plane retardation Re is 1.2 nm, thickness direction retardation Rth is 48 nm, molecular orientation axis is 1.4 °, elastic modulus is longitudinal direction 3.54 GPa, width direction 3 .45 GPa, tensile strength is 142 MPa in the longitudinal direction, 141 MPa in the width direction, stretch rate is 43% in the longitudinal direction, and 49% in the width direction, the kishimi value (static friction coefficient) is 0.65, and the kishimi value (dynamic friction coefficient) is The alkaline hydrolyzability was 0.51, the curl value was −0.4 at 25% RH, and 1.7 when wet. The moisture content is 1.4% by mass, the residual solvent amount is 0.3% by mass, and the thermal shrinkage is −0.09% in the longitudinal direction and −0.08% in the width direction. there were. The foreign matter had a lint of less than 5 pieces / m. The bright spots were 0.02 mm to 0.05 mm less than 10/3 m, 0.05 to 0.1 mm less than 5/3 m, and 0.1 mm or more were zero. These had excellent properties for optical applications. Moreover, adhesion after application was not observed (◯), and the moisture permeability was good (◯).

  A cutting method by the cutting device 22 in the above manufacturing process will be described. The thickness of the film is 92 μm. As shown in FIGS. 2 and 3, the film was heated with warm air before cutting, and then cut with a Gobel blade as a rotary shear blade 46. The temperature of the film 31 at the time of cutting was 50 ° C. The distance from the heating position P1 to the cutting position was 30 mm. The room temperature in the cutting process was 25 ° C.

  As a result of this experiment 1, the cracks on the cut surface were small, and no ears or wavy deformation was observed. In addition, a small amount of cutting waste from the cracks was observed, but it was of no practical problem.

[Experiment 2]
The film 31 was cut in the same manner as in Experiment 1 except that the temperature of the film 31 at the time of cutting was set to 70 ° C. As a result of Experiment 2, cracks on the cut surface were small, and ears, wavy deformation, and cutting debris were hardly observed.

[Experiment 3]
The film 31 was cut in the same manner as in Experiment 1 except that the temperature of the film 31 at the time of cutting was set to 100 ° C. As a result of this experiment 3, cracks on the cut surface were small and almost no cutting debris was observed, but ear standing and wavy deformation were observed.

[Experiment 4]
The experiment was performed in the same manner as in Experiment 1 except that the thickness of the film 31 at the time of cutting was set to 100 μm. As a result of this experiment 4, the cracks on the cut surface were small, and no ears or wavy deformation was observed. In addition, a small amount of cutting waste from the cracks was observed, but it was of no practical problem.

[Experiment 5]
The experiment was performed in the same manner as in Experiment 2 except that the thickness of the film 31 at the time of cutting was set to 100 μm. As a result of this experiment 5, cracks on the cut surface were small, and ears standing, wavy deformation, and cutting debris were hardly observed.

[Experiment 6]
The experiment was performed in the same manner as in Experiment 3 except that the thickness of the film 31 at the time of cutting was set to 100 μm. As a result of this experiment 6, although the cutting resistance increased as the film thickness increased, the cracks on the cut surface were small and almost no cutting debris was observed, but ear standing and wavy deformation were observed.

[Experiment 7]
The experiment was performed in the same manner as in Experiment 1 except that the distance from the heating position P1 to the cutting position was 300 mm. As a result of this experiment 7, no ears standing or wavy deformation was observed, but the film temperature decreased until reaching the cutting position, and cracks and cutting debris were observed.

  The cellulose triacetate film produced by the solution casting method was cut. The rotary shear blade 46 of Experiment 1 of Example 1 was replaced with the score type cutter 61 as shown in FIG. 7, and the film was heated with warm air before cutting and then cut with the score type cutter 61. Other conditions were the same as in Experiment 1 of Example 1.

  As a result of Example 2, cracks on the cut surface were small, and no ears were standing or wavy deformation was observed. In addition, a small amount of cutting waste from the cracks was observed, but it was of no practical problem.

  The cellulose triacetate film produced by the solution casting method was cut. Instead of the incandescent lamp 51 as shown in FIG. 5 as the heating means in Experiment 1 of Example 1, the film was heated by the incandescent lamp 51 before cutting, and then cut by the score type cutter 61. Other conditions were the same as in Experiment 1 of Example 1.

  As a result of Example 3, cracks on the cut surface were small, and no ears were standing or wavy deformation was observed. In addition, a small amount of cutting waste from the cracks was observed, but it was of no practical problem.

  The cellulose triacetate film produced by the solution casting method was cut. The heating means of Experiment 1 of Example 1 was replaced by the infrared heater 55 as shown in FIG. 6, and the film was heated by the infrared heater 55 before cutting and then cut by the score type cutter 61. Other conditions were the same as in Experiment 1 of Example 1.

  As a result of Example 4, cracks on the cut surface were small, and no ears were standing or wavy deformation was observed. In addition, a small amount of cutting waste from the cracks was observed, but it was of no practical problem.

  By setting the film temperature to (Tg−90) ° C. or more and (Tg−30) ° C. or less according to Example 1 above, earring, cracks, and wavy deformation can be prevented, and generation of cutting waste can be prevented. It turns out that a cutting process part can be obtained. And by Examples 2-4, using a rotary shear blade and a rotary leather blade, and using an incandescent lamp or an infrared heater, the above desired effects can be stably obtained. I understand. Therefore, according to the present invention, the film can be cut well.

It is the schematic of the solution casting apparatus which implemented this invention. It is the schematic of the cutting device which implemented this invention. It is sectional drawing in the XX line in FIG. It is the schematic which shows a part of another heating part of a cutting process. It is the schematic which shows another heating part of a cutting process. It is the schematic which shows another cutting process part of this invention. It is sectional drawing which shows the cutting process part of the film by the conventional cutting method.

Explanation of symbols

22 Cutting device 31 Film 31a Cutting / removal part 31b Product part 41 Duct 42 Blower 43 Controller 46 Rotary shear blade 51 Incandescent lamp 55 Infrared heater 61 Score type cutter 62 Roller 63 Rotary blade part P1 Heating position

Claims (7)

In a method of cutting a polymer film with a cutting blade,
When the glass transition temperature of the polymer is Tg (unit: ° C.) and the temperature of the polymer film at the time of cutting is T (unit: ° C.),
Tg−90 ≦ T ≦ Tg−30
The cutting method of the polymer film characterized by satisfy | filling.   The method for cutting a polymer film according to claim 1, wherein the polymer film is continuously conveyed. Heating the polymer film by a heating means before the cutting,
The method for cutting a polymer film according to claim 2, wherein a distance between the heating position and the cutting position is 10 mm or more and 200 mm or less.   The polymer film cutting method according to claim 3, wherein the heating means heats the polymer film from both sides.   The method for cutting a polymer film according to claim 3 or 4, wherein the heating of the polymer film is performed by blowing warm air or irradiating light.   6. The polymer film cutting method according to claim 5, wherein the light irradiation is performed by an incandescent lamp or an infrared heater. The method for cutting a polymer film according to any one of claims 2 to 6, wherein the cutting blade is a rotary shear blade or a rotary leather blade.

Images