JP2014013186A - Surface inspection device and method of flow casting support, and solution film forming method and equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect a defect such as a very small pin hole without any man power.SOLUTION: The surface of a flow casting band 11a wound on a pair of support drums 12 is inspected. The flow casting band 11a of the part wound on the support drums 12 is scanned with a laser in a width direction. A laser 20 reflected on the flow casting band 11a is received by a receiver 16. The receiver 16 blocks unnecessary light by a light blocking plate 21 having a slit opening 21a. By using a positioning unit 18, a scanner 15 and the receiver 16 are positioned at the inspection position of the flow casting band 11a. The scanner 15 and the receiver 16 are arranged to face the circular arc of the flow casting band 11a, and a very small defect such as a pin hole can be accurately inspected.

Description

  The present invention relates to a surface inspection apparatus and method for a casting support, and a solution casting method and equipment.

  A thermoplastic film having light permeability is lightweight and easy to mold, and thus is used in various fields as an optical film. Among them, cellulose ester films using cellulose acylate and the like are optical films (for example, retardation film and polarizing plate protection) which are constituent members of liquid crystal display devices whose market has been expanding in recent years, including photographic photosensitive films. Used in film, etc.).

  Such a film is produced by a solution casting method. In the solution casting method, a polymer solution (dope) containing a polymer and a solvent is allowed to flow on a support to form a cast film. Next, after the cast film becomes hard enough to be transported, it is peeled off from the support as a wet film. Then, this wet film is sent to the drying chamber. In the drying chamber, while the wet film is wound around a roller and conveyed, the solvent is evaporated from the wet film to form a film. In the case of the cooling casting method in which the casting film is solidified by cooling, it is sent to a pin tenter instead of the drying chamber, and the wet film is dried by the pin tenter.

  By the way, with recent high-definition liquid crystal displays (LCDs) and the spread of mobile terminal devices such as smartphones (multifunction mobile phones) and tablet computers, optical films used in these display devices include: What has no fine protrusions or holes on the surface is required.

  For defects such as fine protrusions and holes on the surface of these optical films, as described in Patent Document 1, a continuous running film was scanned with a light beam in the width direction and transmitted or reflected through the film. The inspection light has a slit width less than the diameter of the light beam and enters the light receiver through a light receiving window arranged parallel to the traveling direction of the light beam, and the surface defect of the inspection object is inspected by the photoelectric conversion output from this light receiver. doing. Further, in Patent Document 2, the surface defect is inspected with high accuracy by setting the opening width of the slit within the range of (1/10) to (2/3) of the beam diameter of the inspection light.

JP-A-6-207910 JP-A-8-261949 Korean Patent Publication No. 2009-110082

  However, in Patent Documents 1 and 2, the film as a product is inspected for defects. And the defective part on a film is specified based on defect inspection data, and it displays so that this defective part may not be used on a display apparatus. When commercializing, exclude defective parts. Therefore, in Patent Documents 1 and 2, the use of a defective portion can be avoided, but a fundamental solution of reducing the defective portion of the film itself has not been achieved.

  In the solution casting method, the surface state of the film depends on the surface state of the casting support because the casting film cast on the casting support is peeled off and dried to form a film. Therefore, in the production stage of the casting support, the surface state is inspected, and if fine irregularities are found, this portion is polished if it is convex, and is polished after spot welding if it is concave. In order to prevent fine defects from occurring in the film as a product, surface finishing is performed to eliminate fine irregularities.

  Conventionally, inspecting such a casting support, a skilled inspector visually observes the surface and finds a fine uneven defect. However, with the high definition of LCDs and the spread of mobile terminal devices such as smartphones and tablet computers, the quality requirement level of optical films used in these devices is increasing year by year. Therefore, until now, the defect size required for the surface condition assurance performed by a skilled person has become lower than the visual level. For this reason, there is a limit to the inspection by skilled workers, and a new inspection method for casting supports is required.

  In addition, due to the recent demand for larger LCD screens, the casting support in solution casting is required to have a wide width. However, the width of the steel strip, which is the material of the casting support, is limited by the equipment width of the production line of the steel strip, and cannot easily cope with widening. For this reason, as described in Patent Document 3, a vertical welding band is proposed in which new side plates are vertically welded on both sides of a conventional casting support and the width is increased by the side plate. Further, even in a conventional casting band, when manufacturing an endless band, both end portions of the steel strip are welded in the width direction (lateral welding) and connected in an annular shape. For this reason, even in the conventional casting band, there exists a horizontal welding line extending in the width direction. In a casting band including a welded portion such as a vertical welding line or a horizontal welding line, a strict inspection of a surface defect is performed by a skilled worker when the casting band is delivered. And the pinhole and crack of a welding part are discovered by a strict inspection, and this discovered defect disappears by finishing processes, such as spot welding and subsequent grinding | polishing. Therefore, immediately after being introduced as a casting band to the solution casting apparatus, defects having a size that appears as a film defect are eliminated, and fine uneven defects do not appear in the obtained film.

  However, when the casting band is polished by polishing repair after solution film formation, it is very small at the time of delivery of the casting band. In some cases, pinholes are greatly opened, which leads to defects. Therefore, in the inspection of surface defects at the time of delivery of the casting band, it is necessary to determine the pin-shaped fine pinholes that develop into defects after polishing as defects in consideration of subsequent polishing repairs. Development of inspection methods and inspection devices with high detection accuracy instead of inspection is desired.

  For this reason, it is also possible to apply the defect inspection method for the films as described in Patent Documents 1 and 2 to the defect inspection of the surface of the casting support. However, casting supports such as casting bands and casting drums have a mirror finish, and even if a defect detection method for a film is applied as it is, surface defects cannot be detected accurately. There's a problem.

  The present invention solves such problems, and provides a casting support surface inspection apparatus and method, and a solution casting method and equipment capable of accurately inspecting defects due to fine irregularities of the casting support. The purpose is to provide.

  In the surface inspection apparatus for a casting support according to the present invention, a scanner that scans a laser in the width direction of a continuously running casting support, a receiver that photoelectrically converts a laser reflected by the casting support, and a receiver And a defect determination unit that detects a defect based on the binarized signal and determines a defect when the detected defect is larger than a preset value. The spot diameter of the laser on the casting support is 20 μm or more and 50 μm or less, and the receiver has a light shielding plate having a slit opening arranged along the scanning line of the laser reflected by the casting support. The slit width of the slit opening is 30 to 200 times the spot diameter.

  The casting support is either one of an endless casting band and a casting drum wound around a pair of supporting drums, and the scanning line by the laser is a portion of the casting band wound around the supporting drum. It is preferable that the radius of curvature of the casting support formed on either one of the peripheral surfaces of the casting drum and the scanning line is 100 mm or more and 4000 mm or less. In this case, since the laser is applied to the casting band and the casting drum supported by the support drum, the casting band is less likely to vibrate, and the defect can be detected with high accuracy.

  Moreover, it is preferable to provide the positioning unit which positions a scanner and a receiver with respect to a casting support body. The positioning unit rotates the scanner around a frame arranged so as to face the casting support, and the X axis parallel to the scanning line on the casting support of the laser. A scanner holding unit for fixing, and a receiver holding unit for rotating the receiver around the X axis so that the laser reflected from the casting support is received by the slit opening and fixing the receiver at an arbitrary rotation position preferable. In this case, the scanner and the receiver can be quickly positioned with respect to the casting support to be inspected.

  It is preferable that the scanner holding unit rotates the scanner about the design scanning line in the casting support, and the receiver holding unit rotates the receiver about the design scanning line. The design-time scan line is a design-time scan line in which the laser from the scanner is reflected on the surface of the casting support and this reflected light reaches the receiver. By aligning the surface of the casting support with the positioning unit, the scanner and the receiver are accurately set at the regular inspection position.

  The scanner holding unit and the receiver holding unit are integrated by arranging the scanner and the receiver along the Y axis orthogonal to the X axis, and the integrated scanner holding unit and receiver holding unit are orthogonal to the XY plane including the X axis and the Y axis. It is preferable to have a scanner and receiver rotation holding unit that rotates about the Z axis and fixes the scanner holding unit and the receiver holding unit to the frame at an arbitrary rotation position. In this case, the scanner and the receiver can be arranged to be inclined with respect to the Y axis, and fine unevenness including vertical stripes along the traveling direction of the casting support can be detected. The fine irregularities formed by the vertical stripes are called “stria” because of their shape. This stria is considered to be caused by the distribution of the hardness difference, which seems to be caused by the crystal structure of the material of the casting band itself, by polishing the soft part deeply and polishing the hard part shallowly. Conventionally, this has only been confirmed by an inspector's visual observation, and a standard index has not been obtained. By arranging the scanner and receiver to be inclined with respect to the Y axis, it is possible to capture the streaks, which are fine vertical streaks, as an image, and to display the depth of each stria from the luminance level of each pixel. It is also possible to create an index to be used.

  A Y-axis slide part that holds the rotation holding part of the scanner and the receiver movably with respect to the frame in the Y-axis direction, and a frame X-axis rotation that rotates the frame around the X axis and fixes the frame at an arbitrary rotation position. It is preferable to have a moving holding portion and a Z-axis slide portion that holds the frame X-axis rotation holding portion so as to be movable in the Z-axis direction. By having these slide part and rotation holding part, surface inspection at an appropriate position can be performed according to the degree of curvature of the casting support.

  Furthermore, it is preferable to have an X-axis slide portion that holds the Z-axis slide portion movably in the X-axis direction. In this case, when the scanning line length by the scanner is shorter than the width of the casting support, the casting support is performed by moving the scanner and the receiver in the X-axis direction that is the width direction of the casting support. Surface inspection can be performed on the entire body.

  It is preferable to have a laser pointer that determines the laser scanning direction by irradiating two spots separated on the casting support with spot light. In this case, by finely adjusting each part of the positioning unit so that the scanning light of the scanner is positioned on the spot light irradiated by this laser pointer, the scanner or receiver can be accurately adjusted without touching the surface to be inspected. Alignment becomes possible.

  It is preferable to have a dust removing device for removing dust from the casting support upstream of the scanning support in the running direction of the casting support. In this case, it is possible to prevent fine dust from adhering to the casting support and to eliminate erroneous determination due to these adhering dust.

  In the surface inspection method for a casting support according to the present invention, a laser is scanned in the width direction with respect to a continuously running casting support, the laser reflected by the casting support is photoelectrically converted, and this photoelectric conversion signal is converted into a photoelectric conversion signal. Binarization is performed, a defect is detected based on the binarized signal, and it is determined as a defect when the detected defect is larger than a preset value. The spot diameter of the laser on the casting support is 20 μm or more and 50 μm or less, and the laser is shielded by a light shielding plate having a slit opening arranged along the scanning direction of the laser reflected by the casting support. The width is not less than 30 times and not more than 200 times the spot diameter.

  The casting support is either one of an endless casting band and a casting drum wound around a pair of supporting drums, and the scanning line by the laser is a portion of the casting band wound around the supporting drum. It is preferable that the radius of curvature of the casting support formed on either one of the peripheral surfaces of the casting drum and the scanning line is 100 mm or more and 4000 mm or less. In addition, a scanner holding step for rotating the scanner around the X axis parallel to the scanning line on the laser casting support and fixing the scanner at an arbitrary rotation position, and slitting the laser reflected from the casting support. It is preferable to perform a receiver holding step of rotating the receiver around the X axis so as to be received by the opening and fixing the receiver at an arbitrary rotation position.

  The scanner and the receiver are arranged along the Y axis perpendicular to the X axis to integrate the scanner and the receiver, and the scanner and the receiver are rotated on the XY plane including the X axis and the Y axis to connect the scanner and the receiver. It is preferable to include a rotation holding step of the scanner and the receiver for holding the scanner and the receiver so that the line has an arbitrary inclination angle with respect to the Y axis.

  After the rotation holding step of the scanner and the receiver, a Y-axis slide step for holding the scanner and the receiver movably in the Y-axis direction, and an arbitrary number of times after the scanner and receiver that have passed through the Y-axis slide step are rotated about the X axis. A frame X-axis rotation holding step for fixing at the moving position, and a Z-axis slide step for holding the scanner and receiver that have undergone the frame X-axis rotation holding step so as to be movable in the Z-axis direction intersecting the XY plane. preferable.

  The solution casting method of the present invention uses a casting support evaluated as appropriate by the above-described surface inspection method for a casting support, and a dope containing a polymer and a solvent is poured onto the casting support from a casting die. Thus, a cast film is formed, and the solvent is evaporated from the cast film and peeled off as a wet film.

  The solution casting apparatus of the present invention includes a casting support that has been evaluated as appropriate by the surface inspection method of the casting support, a driving source that rotates the casting support and travels on the casting support surface, A casting die that flows out a dope containing a polymer and a solvent toward a casting support that is driven by a driving source, a membrane solidifying machine that solidifies a casting film made of the dope that has flowed out onto the casting support, and casting. A peeling roller for peeling the membrane from the casting support is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the defect inspection of the casting support body which has conventionally relied on the visual inspection by hand can be automatically performed with high accuracy. Thereby, solution film formation with few defects by fine unevenness | corrugation is attained.

It is a side view which shows the use condition of the surface inspection apparatus of this invention. It is a side view explaining an inspection principle. It is a front view of area A1 in FIG. 2A. It is a side view which shows schematic structure of a positioning unit. It is the same front view. It is the same rear view. It is the same flowchart. It is a side view which shows schematic structure of solution casting apparatus.

  As shown in FIG. 1, a casting support surface inspection apparatus 10 inspects the surface of a casting support 11, for example, an endless casting band 11 a wound between a pair of support drums 12. Find defects such as pinholes and stria. For this reason, the surface inspection apparatus 10 includes a scanner 15, a receiver 16, a defect determination unit 17 (see FIG. 2A), and a positioning unit 18, and is configured as a portable type. Therefore, it is possible to move to a place to be measured and perform defect inspection at an appropriate timing. For example, in addition to the casting chamber of the solution casting equipment, measurement can be performed at an appropriate place such as a factory of a casting support manufacturer.

  As shown in FIG. 2A, the scanner 15 scans the laser beam 20 in the width direction of the casting support 11 that runs continuously. The receiver 16 photoelectrically converts the laser 20 reflected by the casting support 11. The photoelectric conversion signal from the receiver 16 is sent to the defect determination unit 17 through the cable 22. The defect determination unit 17 binarizes the photoelectric conversion signal and detects a defect candidate based on the binarized signal. Then, if the detected defect candidate is larger than a preset threshold value (reference value), it is determined as a defect. The determined defect is stored in the memory together with its position data. This defect position data can be read from the memory by the operator. In this case, a graph showing the defect image and the luminance difference signal of the defect image portion is displayed on the display 17a together with the position data of the casting support.

  In the present embodiment, the defect inspection position is the casting band 11a of the portion wound around the support drum 12. Thereby, the casting band 11a is held in a state of being in close contact with the support drum 12. Therefore, the casting support 11 is not shaken in the thickness direction (Z-axis direction), and an accurate defect inspection can be performed. In the present embodiment, the horizontal axis parallel to the scanning line SL by the laser 20 at the defect inspection position is defined as the X axis, the vertical axis intersecting this is defined as the Y axis, and the XY plane including these X axis and Y axis is defined. The configuration of the positioning unit 18 will be described using the orthogonal axis as the Z axis.

  Detailed configurations of the scanner 15, the receiver 16, the defect determination unit 17, and the like of the present embodiment are basically the same as the conventional ones described in Patent Documents 1 and 2 and the like. However, the configuration of the light shielding plate 21 of the receiver 16 is different from the conventional configuration in that the defect inspection target is a casting support 11 made of a mirror-finished metal (for example, SUS316) band 11a. It has become.

  As is well known, the scanner 15 includes a laser oscillator, a lens group, a polygon mirror, an optical path bending mirror, and the like. The laser emitted from the laser oscillator enters the lens group, and its spot diameter is adjusted. Thereafter, the light enters the polygon mirror that rotates at high speed via the mirror and is reflected there. The reflected laser 20 becomes inspection light in a direction (X axis) perpendicular to the traveling direction of the casting band 11a, and scans the casting band 11a in the width direction.

  As shown in FIG. 2B, the laser 20 emitted from the scanner 15 becomes a constant spot on the casting band 11a. The laser 20 irradiates the laser 20 from the upstream in the running direction of the casting band 11a at an inclination angle θ1 with respect to the normal extending perpendicularly to the casting band 11a from the center in the width direction of the scanning line SL. In contrast, the laser 20 is reflected downstream in the traveling direction of the casting band 11a at an inclination angle θ2. Therefore, when the area A1 on the casting band 11a irradiated with the spot light in FIG. 2A is enlarged and viewed from the front, it becomes a state as shown in FIG. 2B, and becomes an ellipse that is long in the Y-axis direction. The spot diameter Ds on the casting band 11a in the present invention refers to a short axis diameter that does not change in the X direction. The spot diameter Ds of the laser 20 on the casting band 11a is 20 μm or more and 50 μm or less. If the spot diameter Ds is less than 20 μm, the inspection range becomes narrow, which is not preferable. On the other hand, if the spot diameter Ds exceeds 50 μm, the accuracy of defect detection decreases, which is not preferable.

  Since the scanner 15 and the receiver 16 are arranged in a straight line in the Y-axis direction, the spot by the laser 20 on the scanning line SL is reflected in the Y-axis direction by a cylindrical convex mirror when the spot diameter Ds is large. In this case, the spot is elongated and elongated in accordance with the curvature of the arc surface, and becomes substantially elliptical on the light receiving surface of the receiver 16. However, since the spot diameter Ds is as small as 20 μm or more and 50 μm or less, the cast band portion irradiated with the spot is substantially planar, and the action as a convex mirror is minute and can be ignored.

  The laser reflected by the casting band 11 a enters the receiver 16. The receiver 16 has a light shielding plate 21. A slit opening 21 a is formed in the light shielding plate 21. The slit opening 21a is arranged in parallel with the laser scanning line reflected by the casting band 11a.

  The width Ws of the slit opening 21a is determined according to the radius Rd of the support drum 12, the distance Lr from the casting band 11a to the light shielding plate 21 of the receiver 16, and the spot diameter Ds. For example, when the radius Rd of the support drum 12 is 100 mm or more and 4000 mm or less and the distance Lr from the casting band 11a to the light shielding plate 21 of the receiver 16 is 40 mm or more and 100 mm or less, it is 30 times or more the spot diameter Ds. It is preferable that it is 200 times or less. Particularly preferably, when the radius Rd of the support drum 12 is not less than 800 mm and not more than 3000 mm, it is not less than 50 times and not more than 150 times the spot diameter Ds.

  When the slit width Ws of the slit opening 21a is less than 30 times the spot diameter Ds, the laser reflected by the casting support may not enter the slit opening 21a, and the accuracy of defect detection is lowered. Further, if the slit width Ws exceeds 200 times the spot diameter Ds, the contrast is lowered and the accuracy of defect detection is also lowered, which is not preferable.

  As shown in FIG. 1, the positioning unit 18 includes a scanner 15 and a receiver with respect to an arbitrary inspection target surface such as a casting band 11a wound around the support drum 12 or a casting drum (not shown). It is configured so that 16 can be accurately positioned. Therefore, as shown in FIG. 3, the positioning unit 18 includes a frame 31, a scanner holding unit 32 attached to the frame 31, a receiver holding unit 33, a Z-axis rotation holding unit (a rotation holding unit for the scanner and the receiver). 34, a Y-axis slide part 35, an X-axis rotation holding part 36, a Z-axis slide part 37, an X-axis slide part 38, and a laser pointer 39 (see FIG. 1).

  As shown in FIGS. 4 and 5, the frame 31 is formed in a rectangular frame, and is arranged so as to face the casting band 11a as shown in FIG. As shown in FIG. 3, the frame 31 is provided with a scanner holding portion 32, a receiver holding portion 33, a Z-axis rotation holding portion 34, and a Y-axis slide portion 35. The scanner 15 is attached to the frame 31 by a scanner holding part 32, a Z-axis rotation holding part 34, and a Y-axis slide part 35. Similarly, the receiver 16 is attached to the frame 31 by a receiver holding part 33, a Z-axis rotation holding part 34, and a Y-axis slide part 35.

  As shown in FIG. 4, the scanner holding unit 32 includes a pair of side plates 40 and a pair of support plates 41. The side plate 40 clamps and fixes the scanner 15 from both sides. The support plate 41 supports the side plate 40 from both sides, and is formed to protrude from the back plate 42 so as to extend in the Z-axis direction.

  As shown in FIG. 1, the support plate 41 is formed with two arc-shaped long holes 43. The arc-shaped elongated hole 43 is formed on a circle centering on a scanning line SL (hereinafter simply referred to as a scanning line SL) on the casting band 11a in the inspection state set at the defect inspection position. These arc-shaped long holes 43 are formed so as to be spaced apart from each other on a circle. In FIG. 1, the scanning line SL is drawn as a point because it is in a direction perpendicular to the paper surface.

  An attachment screw 44 is attached to the side plate 40. The attachment screw 44 enters each elongated hole 43 and moves in the elongated hole 43. Then, by changing the position of the mounting screw 44 in the long hole 43, the incident angle θ1 of the laser 20 from the scanner 15 with respect to the casting support 11 can be changed. The long hole 43 is formed with a length corresponding to an angle of 15 °, for example. Thereby, the incident angle θ1 of the laser from the scanner 15 can be changed within an angle range of 15 ° with the scanning line SL as the center. After changing the mounting angle, the side plate 40 can be fixed to the support plate 41 by turning the mounting screw 44 in the tightening direction.

  Similarly, as shown in FIG. 3, the receiver 16 is attached to the frame 31 by a receiver holding portion 33, a Z-axis rotation holding portion 34, and a Y-axis slide portion 35. As shown in FIG. 4, the receiver holding unit 33 has the same configuration as the scanner holding unit 32, and a pair of side plates 45 to which the receiver 16 is fixed, and a pair of support plates 46 to which the side plates 45 are attached. Have The support plate 46 is attached to the back plate 42 so as to protrude in the Z-axis direction.

  As shown in FIG. 1, the support plate 46 is formed with two arc-shaped long holes 47. These arc-shaped long holes 47 are formed on concentric circles centering on the scanning line SL on the casting band 11a in the inspection state set at the inspection position, and these two are formed apart from each other. Has been.

  An attachment screw 48 is attached to the side plate 45. The attachment screw 48 enters each elongated hole 47 and moves in the elongated hole 47. Then, by changing the position of the mounting screw 48 in the long hole 47, the reflection angle θ2 of the laser 20 reflected by the casting band 11a is changed. The long hole 47 is formed with a length corresponding to an angle of 15 °, and the mounting angle of the receiver 16 can be changed within an angle range of 15 ° around the scanning line SL. After changing the attachment angle, the side plate 45 can be fixed to the support plate 46 by turning the attachment screw 48 in the tightening direction.

  A laser pointer 39 is attached to the outer surface of the both side plates 45. The laser pointer 39 irradiates the laser toward both ends of the scanning line SL. The fixed positions of the respective portions 32, 33, 34, and 35 are adjusted and aligned so that the point projected on the casting band 11a by the laser pointer 39 and the scanning line of the scanner 15 overlap. Since the two overlap on the casting band 11a, the scanning line by the scanner 15 and the light receiving line by the receiver 16 become the same position on the casting band 11a, and the positioning of the scanner 15 and the receiver 16 is completed.

  As shown in FIG. 5, two mounting screws 52 are attached to the back plate 42. With this attachment screw 52, the back plate 42 is attached to the support plate 54 of the Y-axis slide portion 35. Two arc-shaped long holes 55 are formed in the support plate 54. The two arc-shaped long holes 55 are formed along a circle centering on the scanning center line CL1 parallel to the Z axis passing through the intermediate position in the width direction of the scanning line SL. The mounting screw 52 is inserted into the arc-shaped elongated hole 55, and the back plate 42 can be rotated at an angle of 90 degrees that is the length of the elongated hole 55 around the scanning center line CL1. The back plate 42 can be fixed to the support plate 54 at an arbitrary mounting angle within an angle range of 90 ° around the scanning center line CL1 by turning and tightening the mounting screw 52.

  The back plate 42, the support plate 54, the two arc-shaped elongated holes 55, and the mounting screw 52 constitute the Z-axis rotation holding portion 34.

  Long holes 60 that are long in the Y-axis direction are formed on both sides of the two arc-shaped long holes 55 of the support plate 54, and mounting screws 61 are inserted into the long holes 60. A substrate 62 is attached to both sides of the frame 31. A screw hole 63 is formed in the substrate 62 at a position corresponding to the long hole 60 of the support plate 54. The attachment screw 61 is inserted into the elongated hole 60 and then attached to the screw hole 63. As described above, since the support plate 54 is attached to the substrate 62 of the frame 31 by the long hole 60 and the mounting screw 61, the support plate 54 can be slid by the length of the long hole 55 in the Y-axis direction. Therefore, the scanner 15 and the receiver 16 can be moved in the Y-axis direction in an integrated state. These support plate 54, long hole 60, mounting screw 61, substrate 62, and screw hole 63 constitute a Y-axis slide portion 35 (see FIG. 3).

  As shown in FIG. 1, the lower end portion of the frame 31 is attached to one end portion of a base 65 so as to be rotatable around the X axis by an attachment shaft 66 in the X axis direction. The base 65 is composed of a rectangular frame that is long in the horizontal direction.

  Between the base 65 and the frame 31, a rocking restriction lever 67 is attached obliquely. The swing regulating lever 67 is attached at one end near the one end of the base 65 so as to be swingable by a mounting shaft 68. In addition, a long hole 69 is formed in the longitudinal direction at the other end of the swing restricting lever 67. A mounting screw 70 is placed in the long hole 69. The attachment screw 70 is screwed to the frame 31. Therefore, it is possible to loosen the attachment screw 70 and rotate the frame 31 around the attachment shaft 68 so that the frame 31 can be attached with an arbitrary inclination around the X axis. The attachment shaft 68, the rocking restriction lever 67, and the attachment screw 70 constitute the X-axis rotation holding portion 36 (see FIG. 3).

  A Z-axis slide portion 37 is provided on the lower surface of the base 65. The Z-axis slide part 37 moves and guides the base 65 in the Z-axis direction by a rail (not shown).

  A free wheel 75 is attached to the bottom plate of the Z-axis slide portion 37. In addition, a guide member 76 is disposed at the distal end of the Z-axis slide portion 37 in the Z-axis direction. The guide member 76 extends in the X-axis direction, and is attached parallel to the axis of the support drum 12 at a position below the support drum 12. The tip of the Z-axis slide part 37 is engaged with the guide member 76. Therefore, the Z-axis slide part 37 is guided by the guide member 76 in the X-axis direction and is moved by the free wheel 75.

  A dust removing device 81 is attached to the Z-axis slide portion 37 via a column 80. The dust removing device 81 includes a blower having an ionizer, and blows off dust attached to the casting band 11a. Although the dust removing device 81 is attached to the Z-axis slide portion 37 via the support column 80, it may be attached to the upper and lower ends of the frame 31. In this case, when the traveling direction of the casting band 11a is counterclockwise as shown in FIG. 1, it is attached near the lower end of the frame 31, and when it is clockwise, it is attached near the upper end of the frame 31.

  Next, the operation of the present embodiment will be described with reference to the flowchart shown in FIG. In use, the surface inspection apparatus 10 is carried into a facility in which the casting band 11a that is an inspection object is installed. In the present embodiment, a case will be described where the final inspection is performed before receiving a new casting band 11a from the manufacturer. In addition to this, when the casting band 11a is attached to the solution casting equipment (see FIG. 7), solution film formation is performed, and surface defects of the casting band 11a are inspected at the time of periodic repair, Inventive devices may be used.

  First, the guide member 76 is first attached in the X-axis direction near the site to be examined. The Z-axis slide part 37 is attached to the guide member 76 so that the Z-axis slide part 37 is movable in the X-axis direction.

  The Z-axis slide part 37 and the Y-axis slide part 35 are slid to position the scanner 15 and the receiver 16 on the scanning line of the casting band. At this time, the laser pointer 39 irradiates, for example, two points on the scanning line SL near the both ends to form spots. Next, when the scanner 15 is turned on and scanning with the laser 20 is performed, the scanning line SL is displayed on the surface of the casting band 11a by, for example, a red laser. The Y-axis slide part 35, the Z-axis slide part 37, the X-axis rotation holding part 36, etc. are finely adjusted so that the scanning line SL overlaps, for example, red spot light by the laser pointer 39.

  The scanner holding unit 32 and the receiver holding unit 33 are set so that the incident angle θ1 and the emission angle θ2 are distributed 45 degrees with respect to the normal line CL1 with respect to the casting band surface in accordance with the design scanning line. Therefore, when the X-axis rotation holding part 36, the Y-axis slide part 35, and the Z-axis slide part 37 are finely adjusted and the positional relationship shown in FIG. 1 is obtained, the signal level incident on the receiver 16 becomes a testable level. Is automatically determined, and the operator is notified of the completion of positioning through the display 17a or an alarm. For this reason, the defect determination unit 17 can select a positioning determination mode for determining whether or not the light reception signal level for positioning is appropriate.

  Further, the direction and position of the dust removing device 81 are changed so that dust on the casting band 11a is blown away so as not to reach the position of the scanning line SL. Note that an inhaler for sucking the blown dust may be provided near the dust device.

  When the diameter of the support drum 12 that supports the casting band 11a is changed or when a special defect is inspected, the incident angle θ1 and the emission angle θ2 need to be changed. Further, fine adjustment is performed by changing the mounting position of the receiver holding portion 33. In this case, the mounting screws 44 and 48 are loosened, and the mounting angles of the holding portions 32 and 33 are changed.

  As described above, when the design scanning line is aligned with the desired scanning line on the casting band by the spot light of the laser pointer and the positioning is completed, the defect inspection is performed. In this defect inspection, the casting band can be run at a constant speed within a range of 0.5 m / min to 5.0 m / min, for example, 1.0 m / min.

  For example, red laser light is emitted from the scanner 15, and the red laser light is reflected by the surface of the casting band 11 a and enters the receiver 16. At this time, since the slit opening 21a of the light shielding plate 21 is set to 30 times or more and 200 times or less corresponding to the spot diameter Ds of the casting band 11a, a sufficient amount of received light necessary for defect inspection can be obtained, and the accuracy Good inspection is possible.

  A well-known method is used for defect inspection from the received light signal. For example, the defect determination unit 17 sends the photoelectric conversion signal from the receiver 16 to the defect detection unit 27 via an AGC circuit (auto gain control circuit) and a binarization circuit, and determines the presence or absence of a defect. When the defect is determined, the defect signal and its position data are sent to the data processing unit. The defect signal and the position data are stored in a memory in the data processing unit, and various data processing is performed. In addition to being displayed on the display 17a as required, printing is performed using a printer (not shown). And based on this defect information, the finishing process which eliminates a defect is performed. For example, a polishing process is performed in the case of a convex defect, and a polishing process after spot welding is performed in the case of a concave defect such as a pinhole or a crack, thereby performing a process for eliminating the defect. Then, after such a finishing process, a defect inspection is performed again to determine the presence or absence of a defect. Thus, the inspection process is performed until the defect is eliminated.

  In addition, as the casting band 11a, as in the past, a normal width size having only a horizontal welding line, or a wide size widened in the width direction by joining the central member and the side member by vertical welding. Any of these may be used. In particular, the burden on the inspector can be reduced when the welding line has a length twice the circumference of the band, such as a vertical welding band.

  In the above embodiment, by changing the fixing position of the mounting screw in the long hole, the mounting angle of the scanner and the receiver with respect to the scanning line is changed, and the sliding position in the X-axis, Y-axis, and Z-axis directions is changed. However, the positioning may be performed by adjusting the swing angle by the mounting shaft in addition to the positioning by the long hole or the mounting screw. Further, for fine adjustment, an adjustment mechanism that converts rotational motion into linear motion by screwing screws may be used. Further, these adjusting mechanisms may be automatically positioned by being rotated by a motor.

  As shown in FIG. 1, the laser pointer 39 is provided on the outer peripheral surface of the side plate 45 of the receiver holding portion 33, but this may be provided separately from the surface inspection apparatus 10.

(Solution casting equipment)
The casting band 11a that has passed the defect inspection as described above is installed in the solution casting apparatus 100, and solution casting is performed. As shown in FIG. 7, the solution casting apparatus 100 includes a casting apparatus 101, a first tenter 102, a roll drying apparatus 103, a second tenter 104, a slitter 105, and a winding apparatus 106 on the upstream side. Are connected in series. The kind of polymer is not particularly limited, and a known polymer that can be formed into a film by solution casting may be used. In the following embodiments, a case where cellulose acylate is used as a polymer will be described as an example.

  The casting apparatus 101 includes a casting band 11 a that is stretched around drums 111 and 112, a casting die 114, a duct (film solidifier) 115, a decompression chamber 116, and a peeling roll 117. The casting band 11 a is an endless metal casting support formed in an annular shape, and is stretched around the peripheral surfaces of the first drum 111 and the second drum 112. The casting band 11a is evaluated by the surface inspection apparatus 10 as having no defects. The first drum 111 is rotationally driven by a motor (not shown), whereby the casting band 11a travels in the first direction indicated by the arrow A.

  A casting die 114 is disposed above the first drum 111. The casting die 114 continuously flows the dope 120 to the traveling casting band 11a. Thereby, the casting film 121 is formed on the casting band 11a. The dope 120 is obtained by, for example, dissolving cellulose acylate in a solvent, and is produced by a dope production line (not shown) and supplied to the casting die 114.

  A decompression chamber 116 is provided upstream of the bead 124 from the casting die 114 in the traveling direction of the casting band 11a. The decompression chamber 116 sucks the atmosphere in the upstream area of the bead 124 to decompress the area, and reduces the vibration of the bead 124.

  In order to improve the manufacturing speed, the casting film 121 toward the peeling roll 117 is heated by the second drum 112 and the casting band 11a. Further, at the casting position, the casting band 11a is cooled by the first drum 111 so that the casting band 11a is not excessively heated. For this reason, each drum 111, 112 has a temperature control device (not shown).

  A plurality of ducts 115 are provided side by side along the traveling path of the casting band 11a. Each duct 115 is connected to a hot air controller (both not shown) having a blower, and blows dry air from the outlet. The hot air controller controls the temperature, humidity, and flow rate of the drying air independently. The temperature of the casting film 121 is adjusted by controlling the temperature and flow rate of the drying air and the temperature control of the drums 111 and 112 themselves, and the drying of the casting film 121 proceeds. Then, the casting film 121 is solidified to the extent that it can be conveyed by the first tenter 102, and self-supporting property is imparted. In addition, instead of or in addition to the duct 115, the membrane solidifying machine may be configured by another heater or the like.

  A stripping roll 117 is provided on the upstream side in the traveling direction of the casting die 114 of the first drum 111. The peeling roll 117 supports the casting film 121 when the casting film 121 that has been dried in a state containing a solvent is peeled from the casting band 11a. The cast film 121 that is peeled off, that is, the film 122 is guided to the first tenter 102.

  In the first tenter 102, both side edges of the film 122 are gripped by the clip 123, and a tension in the film width direction is applied while the film 122 is conveyed to widen the width of the film 122. In the first tenter 102, a preheating area, an extension area, and a relaxation area are formed in order from the upstream side. The relaxation area is provided as necessary.

  The first tenter 102 has a pair of rails and a chain (both not shown). The rails are arranged on both sides of the conveyance path of the film 122 with a predetermined interval. This rail interval is constant in the preheating area, gradually becomes wider in the extension area as it goes downstream, and constant in the relaxation area, or becomes gradually narrower as it goes downstream. Clips 123 are attached to the chain at regular intervals.

  The preheating area, the extension area, and the relaxation area are formed as spaces by sending dry air from the duct 115, and there is no clear boundary between these areas. From the slit of the duct 115, dry air adjusted to a predetermined temperature and humidity is sent toward the film 122.

  In the roll drying apparatus 103, the film 122 is wound around a large number of rolls 126 and conveyed. The atmosphere inside the roll dryer 103 is adjusted by a temperature controller (not shown) such as temperature and humidity, and the solvent evaporates from the film 122 while the film 122 is being transported.

  The second tenter 104 has the same structure as the first tenter 102 and includes a clip 128 and a duct 129. The second tenter 104 extends the film 122 while holding the film 122 with the clip 128. By this stretching, a film 122 having desired optical properties is obtained. The obtained film 122 can be used as a retardation film for a liquid crystal display, for example. Note that the second tenter 104 may not be used depending on the optical characteristics of the film 122.

  The slitter 105 cuts out the side part including the retention marks by the clips 123 and 128 of the first tenter 102 and the second tenter 104. The film 122 whose side portions have been cut off is wound into a roll by the winding device 106. The film roll 126 obtained by the present invention can be used particularly for a retardation film and a polarizing plate protective film.

  The width of the casting band 11a is preferably 1.1 times or more and 2.0 times or less of the casting width of the dope 120, for example. The length of the casting band 11a is preferably 20 m or more and 200 m or less, for example. The thickness of the casting band 11a is preferably 0.5 mm or more and 2.5 mm or less, for example. The thickness unevenness of the casting band 11a is preferably 0.5% or less with respect to the total thickness. Further, the surface roughness of the surface on which the casting film 121 is formed is preferably 0.05 μm or less.

  The width of the film as a product is preferably 600 mm or more, and more preferably 1400 mm or more and 2500 mm or less. The present invention is also effective when the film width is greater than 2500 mm. The film thickness is preferably 10 μm or more and 80 μm or less.

(polymer)
The polymer that can be used in the present invention is not particularly limited as long as it is a thermoplastic resin, and examples thereof include cellulose acylate, a lactone ring-containing polymer, a cyclic olefin, and polycarbonate. Of these, cellulose acylate and cyclic olefin are preferable, and cellulose acylate containing acetate group and propionate group and cyclic olefin obtained by addition polymerization are particularly preferable.

(Cellulose acylate)
Only one type of acyl group may be used in the cellulose acylate of the present invention, or two or more types of acyl groups may be used. When two or more kinds of acyl groups are used, it is preferable that one of them is an acetyl group. The ratio in which the hydroxyl group of cellulose is esterified with carboxylic acid, that is, the substitution degree of the acyl group satisfies all of the following formulas (I) to (III) is preferable. In the following formulas (I) to (III), A and B represent the substitution degree of the acyl group, A is the substitution degree of the acetyl group, and B is the substitution degree of the acyl group having 3 to 22 carbon atoms. It is. In addition, it is preferable that 90 mass% or more of triacetyl cellulose (TAC) is a particle | grain of 0.1 mm-4 mm.
(I) 2.0 ≦ A + B ≦ 3.0
(II) 1.0 ≦ A ≦ 3.0
(III) 0 ≦ B ≦ 2.9

  The total substitution degree A + B of the acyl group is more preferably 2.20 or more and 2.90 or less, and particularly preferably 2.40 or more and 2.88 or less. Further, the substitution degree B of the acyl group having 3 to 22 carbon atoms is more preferably 0.30 or more, and particularly preferably 0.5 or more.

  The details of cellulose acylate are described in paragraphs [0140] to [0195] of JP-A-2005-104148. These descriptions are also applicable to the present invention. The same applies to additives such as solvents and plasticizers, deterioration inhibitors, ultraviolet absorbers (UV agents), optical anisotropy control agents, retardation control agents, dyes, matting agents, release agents, and release accelerators. JP-A-2005-104148 describes in detail in paragraphs [0196] to [0516]. Moreover, the cellulose which is a raw material of a cellulose acylate may be obtained from either linter or pulp.

  In the above embodiment, the casting band has been described as the casting support. However, instead of this, a drum may be used as the casting support. In this case, the surface inspection is performed on the drum using the surface inspection apparatus 10. Further, although the surface inspection is performed on the casting band 11 a and the casting drum wound around the support drum 12, the surface inspection may be performed on the casting band 11 a between the support drums 12.

DESCRIPTION OF SYMBOLS 10 Surface inspection apparatus 11 Casting support body 11a Casting band 15 Scanner 16 Receiver 17 Defect determination part 21 Light-shielding plate 21a Slit opening 31 Frame 32 Scanner holding part 33 Receiver holding part 34 Z-axis rotation holding part 35 Y-axis slide part 36 X Axis rotation holding portion 37 Z-axis slide portion 38 X-axis slide portion 39 Laser pointer 41 Support plate 42 Back plate 43, 47, 55, 60 Long hole 44, 48, 52, 61 Mounting screw 62 Substrate 67 Oscillation regulating lever 75 Swivel wheel 76 Guide member 81 Dust removal device 100 Solution film-forming equipment 101 Casting device

Claims (17)

A scanner that scans a laser in the width direction with respect to a continuously running casting support, a receiver that photoelectrically converts the laser reflected by the casting support, and a photoelectric conversion signal from the receiver is binarized, A surface inspection apparatus for a casting support having a defect determination unit that detects a defect based on the binarized signal and determines a defect when the detected defect is larger than a preset value,
The spot diameter of the laser on the casting support is 20 μm or more and 50 μm or less,
The receiver has a light shielding plate having a slit opening arranged along a scanning line of the laser reflected by the casting support,
A surface inspection apparatus for a casting support, wherein a slit width of the slit opening is 30 to 200 times the spot diameter. The casting support is one of an endless casting band and a casting drum wound around a pair of supporting drums,
The scanning line by the laser is formed on any one of a casting band portion wound around the support drum and a peripheral surface of the casting drum,
2. The surface inspection apparatus for a casting support according to claim 1, wherein a radius of curvature of the casting support on which the scanning line is formed is 100 mm or more and 4000 mm or less.   The casting support surface inspection apparatus according to claim 1, further comprising a positioning unit that positions the scanner and the receiver with respect to the casting support. The positioning unit is
A frame arranged to face the casting support;
A scanner holding unit for rotating the scanner around an X axis parallel to a scanning line on the casting support of the laser, and fixing the scanner at an arbitrary rotation position;
A receiver holding part for rotating the receiver around the X axis so that the laser reflected from the casting support is received by the slit opening, and fixing the receiver at an arbitrary rotation position; A surface inspection apparatus for a casting support according to claim 3.   5. The scanner holding unit rotates the scanner around a design scanning line in the casting support, and the receiver holding unit rotates a receiver around the design scanning line. The surface inspection apparatus of the casting support body as described.   The scanner holding unit and the receiver holding unit are integrated by arranging the scanner and the receiver along the Y axis perpendicular to the X axis, and the integrated scanner holding unit and the receiver holding unit are connected to the X axis and the Y axis. And a rotation holding portion for the scanner and the receiver for fixing the scanner holding portion and the receiver holding portion to the frame at an arbitrary rotation position. The surface inspection apparatus for a casting support according to claim 4 or 5. A Y-axis slide unit that holds the rotation holding unit of the scanner and the receiver movably with respect to the frame in the Y-axis direction;
A frame X-axis rotation holding unit that rotates the frame about the X-axis and fixes the frame at an arbitrary rotation position;
The surface inspection apparatus for a casting support according to claim 6, further comprising a Z-axis slide portion that holds the frame X-axis rotation holding portion so as to be movable in the Z-axis direction.   8. The surface inspection apparatus for a casting support according to claim 7, further comprising an X-axis slide portion that holds the Z-axis slide portion so as to be movable in the X-axis direction.   The casting support according to any one of claims 1 to 8, further comprising a laser pointer that determines a scanning direction of the laser by irradiating spot light to two points separated on the casting support. Body surface inspection device.   The casting support according to any one of claims 1 to 9, further comprising a dust removing device that removes dust from the casting support upstream of the scanning line in the traveling direction of the casting support. Surface inspection equipment. A laser is scanned in the width direction of a continuously running casting support,
When the laser reflected by the casting support is photoelectrically converted, the photoelectric conversion signal is binarized, a defect is detected based on the binarized signal, and the detected defect is larger than a preset value In the surface inspection method of the casting support to be judged as a defect,
The spot diameter of the laser on the casting support is 20 μm or more and 50 μm or less,
The laser is shielded by a light-shielding plate having a slit opening arranged along the scanning direction of the laser reflected by the casting support, and the slit width Ws of the slit opening is not less than 30 times 200 with respect to the spot diameter. A method for inspecting a surface of a casting support, characterized in that the surface is doubled or less. The casting support is one of an endless casting band and a casting drum wound around a pair of supporting drums,
The scanning line by the laser is formed on any one of a casting band portion wound around the support drum and a peripheral surface of the casting drum,
12. The surface inspection method for a casting support according to claim 11, wherein the radius of curvature of the casting support on which the scanning line is formed is 100 mm or more and 4000 mm or less. A scanner holding step of rotating the scanner about an X axis parallel to a scanning line on the casting support of the laser, and fixing the scanner at an arbitrary rotation position;
A receiver holding step of rotating the receiver around the X axis so that the laser reflected from the casting support is received by the slit opening, and fixing the receiver at an arbitrary rotation position. The surface inspection method of the casting support body of Claim 12.   The scanner and the receiver are arranged along a Y axis perpendicular to the X axis to integrate the scanner and the receiver, and the scanner and the receiver are rotated on an XY plane including the X axis and the Y axis, 14. The rotation holding step of the scanner and the receiver for holding the scanner and the receiver so that a center line connecting the receiver and the Y-axis has an arbitrary inclination angle is included. Surface inspection method for casting support. A Y-axis slide step for holding the scanner and the receiver movably in the Y-axis direction after the rotation holding step of the scanner and the receiver;
A frame X-axis rotation holding step for fixing the scanner and receiver that have passed through the Y-axis slide step around the X-axis and then fixed at an arbitrary rotation position;
15. The casting support according to claim 14, further comprising a Z-axis slide step that holds the scanner and receiver that have undergone the frame X-axis rotation holding step so as to be movable in the Z-axis direction intersecting the XY plane. Surface inspection method.   A dope containing a polymer and a solvent from a casting die is used on the casting support using the casting support evaluated as appropriate by the surface inspection method for a casting support according to any one of claims 11 to 15. A solution casting method characterized by forming a casting film by pouring, evaporating the solvent from the casting film and stripping it off as a wet film. A casting support evaluated as appropriate by the surface inspection method for a casting support according to any one of claims 11 to 15,
A driving source for rotating the casting support to travel the casting support surface;
A casting die for draining a dope containing a polymer and a solvent toward the casting support traveling by the drive source;
A film solidifying machine for solidifying a cast film made of the dope flowing out on the casting support;
A solution casting apparatus comprising a peeling roller for peeling the casting film from the casting support.

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