JP2008174378A - Conveying roller, and optical film manufacturing method using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conveying roller capable of stably conveying an optical film even in the case of a thin optical film, and capable of restricting a surface fault such as wrinkle and scratch in the optical film. <P>SOLUTION: This conveying roller 26 for conveying a belt-like film is a stepped roller formed so that the diameter of a central part 60 thereof is larger than the diameter of both end parts 62 thereof. The roller surface in both the end parts 62 comprises a holding mechanism for holding the belt-like film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a transport roller and a method for producing an optical film using the same, and in particular, in a process for producing an optical film used in an image display device such as a liquid crystal display, a plasma display, and a cathode-to-cathode display (CRT). The present invention relates to a transport roller for transporting the optical film and an optical film manufacturing method using the transport roller.

  In recent years, the demand for optical films is increasing. Typical examples of the optical film include films having various functions such as an optical compensation film used as a retardation plate in a liquid crystal cell, an antireflection film, and an antiglare film.

  As a representative method for producing such an optical film, while continuously transporting the belt-shaped film with a transport roller, a coating solution is applied to the surface of the belt-shaped film using various coating apparatuses, and then dried. And then cured to form coating films (functional films) having various compositions. However, surface defects such as scratches, wrinkles, and curls often occur when the belt-like film is conveyed, and the surface quality of the obtained film is impaired.

  As this countermeasure, for example, in Patent Document 1, when continuously forming a thin film while running a long base material, by using a reverse crown roll or a stepped roll as a roll for feeding the long base material, A method has been proposed in which excessive tension applied to a long base material is dispersed on the end side in the width direction to suppress wrinkling of the long base material.

  Further, in Patent Document 2, when a polymer film used as an optical application is produced by a solution casting method, a stepped roller having a diameter larger than that of the central portion is used, so that the width of the casting film is reduced. And methods for suppressing the occurrence of curling have been proposed.

Moreover, in patent document 3, when making the optical film used for a liquid crystal display member into a thin film, generation | occurrence | production of wrinkles is suppressed by making the film thickness and film thickness fluctuation | variation of an optical film into a predetermined range, and a yield is reduced. It has been proposed to improve.
Japanese Patent Laid-Open No. 11-310652 JP 2005-111969 A JP 2000-212298 A

  However, various optical films (optical compensation films, etc.) used in liquid crystal display devices are becoming thinner, and even when the above-mentioned Patent Documents 1 to 3 are applied, there are scratches, wrinkles, curls, etc. that occur during transportation of the belt-like film. It is more difficult to suppress planar defects.

  Further, as in the prior art, in order to stably convey the belt-like film, when the uneven surface is formed so as to give holding force to the entire smooth roll, there is also a problem that the entire belt-like film is easily scratched. Such planar defects such as wrinkles and scratches are not preferable, especially in a thin optical film, which causes a significant reduction in display quality. These planar defects are not limited to optical films, but are also the same for film products in which scratches, wrinkles, curls, etc. cause problems in film quality.

  The present invention has been made in view of such circumstances, and can be stably transported even in the case of a thin film, and can suppress the occurrence of surface defects such as scratches, wrinkles, and curls on the film. It is an object of the present invention to provide a transport roller suitable for transporting a film and an optical film manufacturing method using the transport roller.

  In order to achieve the above object, claim 1 of the present invention is a transport roller for transporting a belt-like film, and the transport roller is formed so that the diameters at both ends are larger than the diameter at the center. In addition to the stepped roller, the roller surfaces of the both end portions are provided with a holding mechanism for holding the belt-like film.

  According to the first aspect, in the stepped roller formed so that the diameters of both end portions are larger than the diameter of the central portion, the belt-like film holding mechanism is provided at both end portions. It can be gripped stably only at both ends. Moreover, since it is not necessary to provide a holding mechanism (uneven surface etc.) on the whole surface of a conveyance roller, it can suppress that a wrinkle, an abrasion, etc. are formed over the strip | belt-shaped film whole surface. Therefore, for example, even when the optical film is thinned, it is possible to obtain an optical film with good surface quality free from defects such as wrinkles and scratches.

  In addition, in claim 1, the holding mechanism is a high friction part having a high friction coefficient with respect to the belt-like film and having a sufficient gripping force. For example, the holding mechanism is constituted by an adhesive member, an elastic member, a convex-concave material, or the like. Including.

  A second aspect of the present invention according to the first aspect is characterized in that the diameter of both end portions of the transport roller is 0.01 to 5 mm larger than the diameter of the central portion.

  According to Claim 2, it can suppress that an optical film tends to shrink to the center part of the width direction, and can suppress that a diagonal wrinkle generate | occur | produces in a diameter difference part. In addition, it is more preferable that the diameter of the both ends of a conveyance roller is 0.01-2 mm larger than the diameter of a center part.

  A third aspect of the present invention is characterized in that, in the first or second aspect, the holding mechanism is a mechanism for generating an adhesive force on the roller surfaces of the both end portions.

  According to the third aspect, since the holding mechanism has adhesive force, it can be stably gripped without damaging the belt-like film.

  A fourth aspect of the present invention is characterized in that, in the third aspect, the adhesive force is 10 to 150 hPa.

  Thereby, since the holding mechanism of a conveyance roller has appropriate adhesiveness and peelability, it can convey a strip | belt-shaped film stably. The adhesive strength is more preferably 50 to 100 hPa.

  A fifth aspect of the present invention according to the third or fourth aspect is characterized in that an error in the adhesive force is 20% or less in the rotation direction of the transport roller.

  If the error of the adhesive force is large in the rotation direction of the transport roller, the grip force of the belt-like film changes with rotation, so that the belt film is likely to become unstable and unfavorable. Such a problem can be eliminated by using the above-mentioned range of claim 5.

  A sixth aspect of the present invention is characterized in that, in any one of the first to fifth aspects, at least the roller surface of the both end portions is constituted by a rubber member, and the rubber hardness of the rubber member is 5 to 50 degrees. To do.

  According to the sixth aspect of the present invention, the rubber member is preferable because it has both proper adhesiveness and peelability.

  A seventh aspect is characterized in that, in the sixth aspect, an error in the rubber hardness is 20% or less in the rotation direction of the transport roller.

  If there is a large error in rubber hardness in the rotation direction of the transport roller, the difference in diameter between the center and both ends of the stepped roller will change when the strip film is wrapped around the transport roller, or the grip force will be It is not preferable because it is likely to change and the conveyance of the belt-like film becomes unstable. Such a problem can be eliminated by using the above-mentioned range of claim 7.

  An eighth aspect according to any one of the first to seventh aspects, wherein the roller surfaces of the both end portions have conductivity, and the charge amount on the roller surfaces of the both end portions after contacting with the belt-like film is an absolute value. It is characterized by being 2.0 kV or less.

  Thereby, when a strip | belt-shaped film and a conveyance roller contact at the time of conveyance, it can suppress that dust and dust adhere to a conveyance roller by static electricity or friction. In addition, said charge amount is the value measured by making a strip | belt-shaped film convey at a speed | rate of 20-60 m / min, and making an electrostatic voltmeter (product made from a cisid electrostatic; STATIRON-DZ3) adjoin to a strip | belt-shaped film.

  A ninth aspect of the present invention is characterized in that, in any one of the first to eighth aspects, the holding mechanism is a mechanism that imparts a non-smooth surface to the roller surfaces of the both end portions.

  In claim 9, the non-smooth surface includes a rough surface (mat type), a groove, and a dimple type surface.

  A tenth aspect is characterized in that, in the ninth aspect, the non-smooth surface includes a plurality of grooves, and the groove pitch is 0.1 to 10 mm.

  As a result, not only can the both ends of the belt-like film be stably held, but particularly, air entrainment that is likely to occur when the belt-like film is transported at high speed is prevented, and the belt-like film slides on the contact surface of the transport roller, thereby causing scratches. Can be prevented from occurring. In addition, in Claim 10, it is more preferable that a groove pitch is 0.5-5 mm.

  An eleventh aspect is characterized in that, in the ninth or tenth aspect, the non-smooth surface is formed by forming a concave portion on the smooth surface, and the concave portion ratio is 20 to 80%.

  Thus, by forming a plurality of concave portions on the surfaces of both end portions of the transport roller, the belt-like film can be held on the surface and can be stably gripped with a high frictional force. Therefore, it can be stably conveyed without damaging the belt-like film.

  A twelfth aspect is characterized in that, in any one of the first to eleventh aspects, the belt-like film is an optical film.

  Examples of such an optical film include films having various functions such as an optical compensation film for liquid crystal display plates, an antireflection film, and an antiglare film.

  A thirteenth aspect is the one according to the twelfth aspect, wherein the optical film is an optical compensation film.

  As described above, the present invention is particularly effective when manufacturing a thin optical compensation film which is easily scratched and easily wrinkled. In addition, the film thickness of an optical compensation film is 20-110 micrometers.

  According to a fourteenth aspect of the present invention, in order to achieve the above object, a step of applying an optical functional layer on a continuously running belt-like film, a step of drying the applied optical functional layer, and curing the optical functional layer The manufacturing process of the optical film including at least a process WHEREIN: The conveyance roller of any one of Claims 1-13 is used for conveyance of the said strip | belt-shaped film, The manufacturing method of the optical film characterized by the above-mentioned is provided.

  Here, the step of curing the optical functional layer includes a step of performing photopolymerization or thermal polymerization.

  A fifteenth aspect is characterized in that, in the fourteenth aspect, the holding width of the band-shaped film at the both end portions is 0.1 to 10% with respect to the entire width of the band-shaped film.

  Thereby, it can grip and convey stably at the both ends of a strip | belt-shaped film, without producing a wrinkle, an abrasion, etc. in the center part of a strip | belt-shaped film.

  According to the present invention, for example, even when the optical film is thinned, the optical film can be stably conveyed, and occurrence of planar defects such as wrinkles and scratches on the optical film can be suppressed.

  Preferred embodiments of a transport roller according to the present invention and an optical film manufacturing method using the same will be described below with reference to the accompanying drawings.

  First, the manufacturing method of the optical film in this invention is demonstrated.

  FIG. 1 is a schematic view of a manufacturing process 10 of an optical compensation film (optical film) incorporating the conveyance roller of the present invention. In addition, the arrangement | positioning form of the conveyance roller in the manufacturing process 10 of an optical compensation film shall not be limited to the aspect of FIG.

  As shown in FIG. 1, the optical compensation film manufacturing process 10 mainly includes an alignment film forming process 12, a rubbing process 14 for performing a rubbing process on the alignment film, and a liquid crystal layer forming process 16 after the rubbing process. And.

  The long transparent film 24a fed from the long roll (film roll) 20 of the film by the feeder 22 is conveyed by the conveyance roller 26 and dust is removed by the surface dust remover 28, and then the alignment film forming step 12 is performed. Sent.

  In the alignment film forming step 12, a coating liquid containing an alignment film forming resin is applied by the coating machine 30, and dried in the drying zone 32, whereby a resin layer is formed on the surface of the transparent film 24a. Then, the transparent film 24a is further sent to the rubbing treatment step 14. In addition, you may wind up the film obtained here once.

  In the rubbing treatment step 14, a rubbing device comprising a rubbing roller 34, a guide roller 36 fixed to a roller stage with a spring, and a dust remover 37 provided to the rubbing roller is used to rub the transparent film 24b having an alignment film forming resin layer. Processing is performed. Thereby, the surface of the formed alignment film is dust-removed by the surface dust remover 38 provided adjacent to the rubbing device. A known device other than the above may be used as the rubbing device. After the dust is removed, the transparent film 24 c on which the alignment film is formed is transported by the transport roller 40 and further sent to the liquid crystal layer forming step 16.

  In the liquid crystal layer forming step 16, a coating liquid containing a liquid crystalline discotic compound is applied onto the alignment film of the transparent film 24 c by the coating machine 42, and after the solvent is evaporated, the coating layer is formed in the heating zone 44. It is heated to the discotic nematic phase formation temperature (here, the residual solvent in the coating layer also evaporates). Thereby, a liquid crystal layer having a discotic nematic phase is formed.

  The liquid crystal layer is then irradiated with ultraviolet rays from an ultraviolet (UV) lamp 46, and the liquid crystal layer is crosslinked. In order to crosslink the liquid crystal layer, it is necessary to use a liquid crystal discotic compound having a crosslinkable functional group as the liquid crystal discotic compound. When a liquid crystal discotic compound having no crosslinkable functional group is used, this ultraviolet irradiation step is omitted and the liquid crystal is immediately cooled. In this case, the cooling needs to be performed rapidly so that the discotic nematic phase is not destroyed during cooling.

  The transparent film on which the alignment film and the liquid crystal layer are formed is inspected for an abnormality by measuring the optical characteristics of the transparent film surface by the inspection device 48. Next, the protective film 50 is laminated on the surface of the liquid crystal layer by the laminating machine 52, and is taken up by the take-up device 54.

  In the optical compensation film manufacturing process 10, when the transparent films 24 a to 24 c are transported by the transport rollers 26 and 40, if the transparent films 24 a to 24 c are thinned, wrinkles or scratches are formed. Etc.

  For this reason, in the present invention, the transport rollers 26 and 40 are stepped rollers in which the diameters of both end portions are formed larger than the center portion, and further, a holding mechanism that holds the transparent films 24a to 24c at both end portions is provided. The configuration.

  Hereinafter, the conveyance roller according to the present invention will be described. Since the transport rollers 26 and 40 have the same configuration, the description of the transport roller 40 is omitted.

  FIG. 2 is a schematic diagram illustrating the conveyance roller 26 of the present embodiment. As shown in FIG. 2, the transport roller 26 according to the present embodiment is a stepped roller in which the diameters of both end portions 62 are formed larger than the central portion 60, and transparent films 24 a to 24 b are formed on the roller surfaces of both end portions 62. An adhesive member 64 is provided as a holding mechanism for holding 24c.

  The difference between the diameter Z1 of the central portion 60 and the diameter Z2 of both end portions 62 (hereinafter referred to as “diameter difference”) is preferably 0.01 to 5 mm, and preferably 0.01 to 2 mm. Is more preferable. That is, if the diameter difference is too smaller than 0.01 mm, not only the holding force of the transparent films 24a to 24b at the both end portions 62 of the transport roller 26 is reduced, but there is almost no gap between the transparent films 24a to 24c. The accompanying air cannot be excluded. For this reason, there is a possibility that the transport roller 26 may idle and damage the transparent films 24a to 24c, which is not preferable. Further, if the diameter difference exceeds 5 mm, the transparent film 24a to 24c may have slanted creases or cuts in the diameter difference portion, and the transparent films 24a to 24c may be easily damaged or the conveyance may be unstable. It is not preferable.

  The width W1 of the central portion 60 is preferably shorter than the width Wf of the transparent films 24a to 24c in a range of 20 mm to 100 mm.

  The diameter Z1 of the central portion 60 of the transport roller 26 is preferably in the range of φ70 ≦ Z1 ≦ φ110.

  An adhesive layer is formed on the surfaces of both end portions 62 of the transport roller 26 by, for example, attaching a sheet-like adhesive member or applying an adhesive material.

  As the adhesive member 64, a terpene resin, a rosin resin, a xylene resin, an alkylphenol resin, a tackifier such as a coumarone indene resin, an adhesive material such as a rubber, an acrylic resin, a silicone resin, or the like can be used. In particular, an adhesive rubber-based resin is preferable.

  The adhesive force of the adhesive member 64 is preferably 10 to 150 hPa, and more preferably 50 to 100 hPa. The adhesive strength can be measured, for example, by the maximum load at the time of peeling when a stainless steel terminal of a predetermined size is pressed against the adhesive member surface of the transport roller 26 for a certain period of time at a constant pressure and then pulled up at a constant speed. See Example B). Further, from the viewpoint of maintaining the holding force of the transparent film uniformly and stably, the error in the rotation direction of the adhesive force (of the conveying roller 26) is preferably 20% or less, and more preferably 10% or less.

  Further, when an adhesive rubber-based resin is used as the adhesive member, the rubber hardness according to JIS-A hardness is preferably 5 to 50 degrees, and more preferably 20 to 40 degrees. The JIS-A hardness is a value measured by a durometer A manufactured by Shore, and is a value obtained by a hardness test method for vulcanized rubber and thermoplastic rubber described in JIS-K-6253.

  The error of the rubber hardness in the rotation direction (of the conveyance roller 26) is preferably 20% or less. This is because, when the error of the rubber hardness in the rotation direction of the adhesive rubber resin (conveying roller 26) exceeds 20%, when the conveying roller 26 is rotated around the transparent film, the diameter difference fluctuates. This is because the holding force also fluctuates and the conveyance is likely to become unstable.

  In addition, when the adhesive rubber-based resin and the transparent film come into contact with each other, static electricity is likely to occur, which makes it easy for foreign matters such as dust and dirt to adhere to the transparent film, damaging the transparent film and making the transport unstable. Cause.

  For this reason, it is preferable to impart electrical conductivity to the adhesive member 64 to prevent charging. Specifically, it is preferable that the charge amount of the adhesive member after contacting the transparent film for a certain time is 2.0 kV or less in absolute value. The charge amount of the adhesive member can be measured with an electrostatic voltmeter or the like.

  As a method for imparting conductivity, it is preferable to contain a conductive material such as conductive carbon fiber or conductive carbon black in the adhesive rubber-based resin. In order to improve the conductivity of the adhesive member uniformly and efficiently, it is more preferable to use the conductive carbon black and the conductive carbon fiber in combination. That is, in the rubber-based resin, the conductive carbon black particles are dispersed separately and independently insulated, so that the conductive path is sufficient unless they are blended in such a large amount that the particles are close to each other. On the other hand, if it is added too much, the tackiness is lowered. For this reason, the electroconductive carbon black currently disperse | distributed can be electrically connected by mix | blending electroconductive carbon fiber.

  As the conductive carbon black, acetylene black or ketjen black having an average particle diameter of 20 to 50 μm can be preferably used, and as the conductive carbon fiber, those having a fiber length of 10 mm or less, preferably 2 to 6 mm can be used.

  The amount of the conductive material blended in the rubber-based resin is preferably in a range where both the adhesiveness and conductivity of the rubber-based resin are compatible, and is preferably 5 to 40% by mass. Note that the conductive material is not limited to the conductive carbon.

  The surface of the central portion 60 of the transport roller 26 is a smooth surface that does not damage the transparent film 24a even if it contacts the transparent film 24a. Although the material of the center part 60 of the conveyance roller 26 is not specifically limited, the thing which does not have a bad influence on the quality of the transparent film 24a and has small frictional force is preferable.

  Next, the operation of the conveying roller 26 according to the present invention will be described with reference to FIG. FIG. 3 is a schematic diagram showing a state in which the transparent film 24a is being transported by the transport roller 26 of FIG.

  As shown in FIG. 4, the transparent film 24 a is transported while being held at a high frictional force by the adhesive members 64, 64 formed on the surfaces of the both ends 62, 62 of the transport roller 26 at both ends. At this time, the holding width X between the transparent film 24a and the adhesive member 64 formed on the surfaces of both end portions 62 is set to be 0.1 to 10% with respect to the total width Wf of the transparent film 24a.

  Thereby, the both ends of the transparent film 24a can be hold | maintained with the high frictional force by the adhesive members 64 and 64, and it can convey stably. Moreover, since the space | gap 61 is formed between the transparent film 24a and the conveyance roller 26, accompanying air can be removed and it can suppress that the conveyance roller 26 idle | rotates and damages the transparent film 24a. In addition, since the vicinity of the center of the transparent film 24a is in contact with a smooth surface having a small frictional force at the central portion 60 of the transport roller 26, the transparent film 24a is not damaged.

  As described above, the transparent film 24a can be stably held and transported only at both ends without causing scratches or wrinkles on the surface of the transparent film 24a. Therefore, it is possible to obtain an optical film having a good surface quality free from wrinkles and scratches.

  FIG. 4 is a schematic diagram for explaining another embodiment of the transport roller. 4A is a schematic diagram for explaining the conveyance roller 26 ′, and FIG. 4B is an enlarged schematic diagram showing the surface portions of both end portions 62 of FIG. 4A.

  The transport roller 26 ′ in FIG. 4 is formed in substantially the same manner as FIG. 2 except that both end portions 62 are provided with a plurality of parallel grooves 68 (non-smooth surfaces) instead of the adhesive member 64. In FIG. 5, members having the same functions as those in the above-described embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  A plurality of grooves 68 are formed in the SGR structure (spiral shape) on the surfaces of both end portions 62 of the transport roller 26 ′. The groove depth d is preferably in the range of 0.01 to 2.0 mm, the groove pitch p is preferably 0.5 to 5 mm, and the groove width b is 0.1 to 2 mm. Is preferred. In addition, the shape of a groove | channel is not limited to the aspect of FIG.

  The material of the both end portions 62 of the transport roller 26 'is not particularly limited, but the same material as the central portion 60 of the transport roller 26', an adhesive member, or the like can be preferably used.

  With this configuration, the transparent film 24a can be conveyed while being stably held by the high frictional force of the both end portions 62 and 62 of the conveying roller 26 '. Furthermore, entrained air generated by the conveyance of the transparent film 24a can be removed from the gap formed between the concave portion of the groove and the transparent film 24a, so that the transparent film 24a floats from the conveyance roller 26 ' Can be suppressed.

  As mentioned above, although preferable embodiment of the manufacturing method of the conveyance roller which concerns on this invention, and an optical film using the same was described, this invention is not limited to the said embodiment, Various aspects can be taken.

  For example, in the embodiment of FIG. 4 described above, not only a plurality of parallel grooves may be formed as the non-smooth surface, but fine irregularities (also referred to as mats or rough surfaces) may be imparted to the surfaces of both end portions 62. . The uneven surface can be formed by glass beads, sandblasting or the like. Moreover, after forming a recessed part in the surface of the both ends 62, it is good also as a dimple type which grind | polishes the surface and makes a surface contact. In this case, the recess ratio is preferably 20 to 80%. Thereby, it can hold | maintain stably in the both ends of a conveyance roller, without damaging the transparent film 24a. The above embodiments can be arbitrarily combined.

  Moreover, in the said embodiment, although the example which integrated the conveyance roller which concerns on this invention in the manufacturing process 10 of the optical compensation film was demonstrated, it is not limited to this, For other thin film films, for example, for optical compensation films The present invention can also be applied to manufacturing and transporting processes for base films, antireflection films, and thin films for optical use used in various image display devices.

  The present invention will be described in more detail based on examples, but the present invention is not limited thereto.

  In this example, a transparent film of triacetyl cellulose film (Fujitac, manufactured by Fuji Film Co., Ltd.) having a thickness of 80 μm and a width of 1470 mm was used as the transparent film 24a. Further, as the transport roller 26, a material having a diameter Z1 of the central portion 60 of 90 mm and aluminum is used.

[Example A]
(Example 1)
First, the relationship between the diameter difference between the central portion 60 and both end portions 62 of the transport roller 26 and the holding force of the transparent film 24a was examined as follows.

A conveyance roller 26 provided with an adhesive member having a diameter difference of 0.12 mm and an adhesive force at both ends 62 of 80 hPa was used. The transport roller 26 was placed on the optical film production line 10 and the transparent film 24a was held at 180 ° to start transport. At this time, the conveyance roller 26 can be started stably at a two-stage acceleration rate (0.083, 0.167 m / sec ² ) from a stationary state, and can be stably conveyed without causing wrinkles or scratches on the transparent film 24a. Tension and wrap angles were measured. In addition, the conveyance speed of the transparent film 24a was 150 m / min.

  The results are shown in FIGS. 5 (A) and 5 (B). In FIG. 5B, the wrap angle θ (99 °, 57 °, 32 °, and 14 °) of each transport roller when the tension is the lowest (70 N) is shown in FIG.

(Example 2)
Example 1 was the same as Example 1 except that the diameter difference of the conveying roller 26 was set to 0.2 mm.

(Example 3)
The same procedure as in Example 1 was performed except that a transport roller (diameter difference of 80 μm) in which a PET (polyethylene terephthalate) tape having a thickness of 80 μm was wound around both ends of a flat roller having a smooth surface was used.

(Comparative Example 1)
Example 1 was performed except that a flat roller having a smooth surface and no diameter difference was used.

As shown in FIG. 5 (A), when the acceleration rate is 0.083 m / sec ² , the transport rollers of Examples 1 to 3 are both in the region of lower tension and lower wrap angle than Comparative Example 1. There was no slip or wrinkle. However, the difference in tension and wrap angle due to the difference in diameter of the transport roller was unclear.

Next, when the acceleration rate is set to 0.167 m / sec ² , as shown in FIG. 5B, the conveyance rollers 26 of Examples 1 and 2 satisfying the range of the diameter difference of 0.1 to 5 mm are low laps. It was found that the tension of the transparent film 24a can be maintained high even at an angle and can be stably conveyed. Moreover, in Example 3 with a small diameter difference, the retention strength of the transparent film 24a was small, and the wrap angle was higher than Examples 1 and 2.

  On the other hand, in Comparative Example 1 using a conventional smooth roll, in the wrap angle and tension region shown in FIG. 5 (B), wrinkles or scratches occurred on the transparent film 24a. It could not be transported stably.

  As shown in FIG. 6, it can be seen that the contact area between the transport roller 26 and the transparent film 24a is smaller when it can be held at a lower wrap angle, and the occurrence of surface defects such as scratches, wrinkles, and curls can be reliably suppressed.

  As described above, wrinkles are generated even in a low wrap angle and low tension region by applying the conveyance roller of the present invention that is a stepped roller having a diameter difference of 0.1 to 5 mm and that has adhesiveness at both ends. It was found that the transparent film 24a can be conveyed stably without causing any scratches or scratches. Further, since the wrap angle is low and the tension is low, it has been found that the transparent roller 24a is not easily damaged or scratched by the transport roller.

[Example B]
Next, the transport roller 26 in which adhesive layers having different adhesive forces were formed on both end portions 62 of the transport roller 26 in FIG. 2 was produced. The composition of the pressure-sensitive adhesive layer is obtained by blending a static neutralizing fiber or a surfactant with a urethane or polyolefin material.

  Adhesive layers were formed on the surfaces of both end portions 62 and 62 of the conveying roller 26 in FIG. 2 and placed in the optical compensation film manufacturing process 10 in FIG. Then, the surface quality of the transparent film 24a after being conveyed at a conveyance speed of 150 m / min was visually observed to check for the occurrence of wrinkles and scratches. In addition, the adhesive force measured the adhesive force of the adhesive layer of the both ends 62 surface of the conveyance roller 26 by the method of FIG. 8 mentioned later. The film surface quality was evaluated by visually observing the presence or absence of wrinkles and scratches. The results are shown in Table 1.

  As shown in Table 1, in Examples 1 to 9 to which adhesive strength was applied, the transparent film 24a could be conveyed while being stably held, and no noticeable wrinkles or scratches were observed. On the other hand, in Comparative Example 1 in which no adhesive force was applied, the transparent film 24a could not be stably held, and wrinkles and scratches were observed.

  In addition, when the adhesive strength was in the range of 10 to 150 hPa, the film could be conveyed while being stably held at both ends of the transparent film 24a, and almost no wrinkles or scratches were observed on the transparent film 24a.

  On the other hand, if the adhesive force is less than 10 hPa, the holding force of the transparent film 24a is slightly lowered and the conveyance becomes unstable. If the adhesive force exceeds 150 hPa, the adhesive force is too high and the peelability is poor and the conveyance becomes unstable. (Examples 8 and 9).

  Further, in Examples 5 and 7 in which the error in adhesive force or the error in rubber hardness exceeds 20%, the conveyance stability is slightly lowered, and the surface quality of the transparent film 24a is also lowered although it is within the allowable range as a product. did.

  Next, when the adhesive strength was 80 hPa, errors in the rotational direction and the width direction of the adhesive strength were measured. In addition, the measuring method of adhesive force was performed as follows.

  As shown in FIG. 7, a pressure-sensitive adhesive roller for measurement 70 having an adhesive layer formed on the entire surface of the smooth roller was prepared. The adhesive strength is 6 points of A, B, C, D, E, and F (refer to FIG. 7A) in the width direction of the measuring adhesive roller 70, and 1, 2, 3, 4 in the rotational direction. Measurements were made on 4 points (see FIG. 7B), and the average value was obtained.

  As a measuring method, in the apparatus 72 shown in FIG. 8, a stainless steel terminal 74 having a tip area of 10 mm × 10 mm is pressed against the pressure-sensitive adhesive roller 70 for 10 seconds at a pressure of 3 kgf, and then the stainless steel terminal 74 is attached at a speed of 200 m / min. The maximum load when peeling and peeling was measured. The results are shown in Table 2.

  The adhesive force was extremely small at 12% or less in both the width direction error and the rotation direction error, and was able to be stably conveyed by gripping at both ends 62.

[Example C]
Next, a conductive adhesive roller (clean dash E, manufactured by Techno Roll) formed by blending a conductive material with an adhesive rubber resin was prepared.

  Then, the charge amount in the conductive adhesive roller was measured when the nip pressure of the conductive adhesive roller and the transport speed of the transparent film 24a were changed.

  In FIG. 1, the amount of charge was measured by conveying the transparent film 24a at a speed of 20 to 60 m / min and measuring the absolute value of the amount of charge in the conductive adhesive roller with an electrostatic voltmeter. The results are shown in Table 3.

  As shown in Table 3, it was found that the charge amount of the conductive adhesive roller after contact was only charged at −0.03 kV at the maximum, and the absolute value satisfied 2.0 kV or less (target range). Thereby, even if it did not newly install the static eliminator for neutralizing the surface of a conveyance roller, it turned out that it can suppress that static electricity generate | occur | produces in the transparent film 24a.

It is the schematic which shows the manufacturing process of the optical compensation film to which this invention is applied. It is the schematic which shows the conveyance roller in embodiment which concerns on this invention. It is a figure explaining the effect | action of FIG. It is the schematic which shows the conveyance roller in other embodiment of this invention. It is a graph which shows the result of a present Example. It is a figure which shows the wrap angle of the adhesive roller in a present Example. It is explanatory drawing explaining the adhesive roller in a present Example. It is the schematic which shows the measuring apparatus of the adhesive roller in a present Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Manufacturing process of optical compensation film, 24a, 24b, 24c ... Transparent film (optical film), 26, 26 ', 40 ... Conveyance roller, 60 ... Center part, 62 ... Both ends, 64 ... Adhesive member (holding mechanism) ), 68 ... Groove (holding mechanism)

Claims (15)

A transport roller for transporting a belt-shaped film,
The transport roller is a stepped roller formed such that the diameter of both end portions is larger than the diameter of the center portion, and the roller surface of the both end portions is a holding mechanism for holding the belt-like film A conveying roller characterized by comprising:   The diameter of the both ends of the said conveyance roller is 0.01-5 mm larger than the diameter of the said center part, The conveyance roller of Claim 1 characterized by the above-mentioned.   The transport roller according to claim 1, wherein the holding mechanism is a mechanism that generates an adhesive force on the roller surfaces of the both end portions.   The conveyance roller according to claim 3, wherein the adhesive force is 10 to 150 hPa.   5. The transport roller according to claim 3, wherein an error of the adhesive force is 20% or less in a rotation direction of the transport roller.   The roller according to any one of claims 1 to 5, wherein at least the roller surfaces of the both end portions are made of a rubber member, and the rubber hardness of the rubber member is 5 to 50 degrees. .   The conveyance roller according to claim 6, wherein an error of the rubber hardness is 20% or less in a rotation direction of the conveyance roller.   The roller surfaces at both ends have conductivity, and the charge amount on the roller surfaces at both ends after contact with the belt-like film is 2.0 kV or less in absolute value. The conveying roller according to any one of the above.   The conveying roller according to claim 1, wherein the holding mechanism is a mechanism that imparts a non-smooth surface to the roller surfaces of the both end portions.   The conveyance roller according to claim 9, wherein the non-smooth surface includes a plurality of grooves, and the groove pitch is 0.1 to 10 mm.   11. The transport roller according to claim 9, wherein the non-smooth surface has a recess formed on the smooth surface, and the recess ratio is 20 to 80%.   The transporting roller according to claim 1, wherein the belt-like film is an optical film.   The transport roller according to claim 12, wherein the optical film is an optical compensation film. In a process for producing an optical film comprising at least a step of applying an optical functional layer on a continuously running belt-shaped film, a step of drying the applied optical functional layer, and a step of curing the optical functional layer.
An optical film manufacturing method using the transport roller according to any one of claims 1 to 13 for transporting the belt-shaped film.   The method for producing an optical film according to claim 14, wherein a holding width of the belt-like film at the both end portions is 0.1 to 10% with respect to a total width of the belt-like film.

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