JP7720134B2 - Manufacturing method of resin film roll - Google Patents

Description

The present invention relates to a method for manufacturing a resin film roll and a method for manufacturing a resin film roll.

Long resin films are wound into rolls, as described in Patent Document 1, for example, and are stored or transported as resin film rolls, or are sold as products themselves.

Japanese Patent Application Laid-Open No. 2003-147092

When a long length of resin film is wound into a roll, air tends to get caught in it. When air gets caught in this way, streak-like defects that extend circumferentially around the roll (the direction in which the resin film extends) occur within the formed roll. Because these defects occur within the roll, it is not possible to inspect the roll for defects simply by visually inspecting its appearance.

One object of the present invention is to provide an inspection method capable of inspecting for streak-like defects in a resin film roll formed from a long resin film, and a method for manufacturing a resin film roll that includes this inspection method. Another object of the present invention is to provide a resin film roll that is substantially free of streak-like defects.

The inspection method of the present invention includes a winding hardness distribution acquisition process in which a hammer is moved along the axial direction of a resin film roll formed by winding a resin film, striking the surface of the resin film roll with the hammer, measuring the deceleration until the hammer hits the surface of the resin film roll and stops, and acquiring the change in deceleration in the axial direction as a winding hardness distribution in the axial direction; and a determination process in which the quality of the resin film roll is determined based on the winding hardness distribution. In the determination process, the resin film roll is determined to be a good product if both a first condition and a second condition are satisfied, and the resin film roll is determined to be a defective product if at least one of the first condition and the second condition is not satisfied. The first condition is that the reference standard deviation, which is the standard deviation of the winding hardness distribution, is 3 or less, and the second condition is that the difference between the maximum and minimum values in the winding hardness distribution is 18 G or less.

The inventors of the present application discovered that in the winding hardness distribution acquired using the hammer, there is a correlation between locations where streak defects exist and other locations. In the above inspection method, the winding hardness distribution is acquired in the winding hardness distribution acquisition process. The quality of the resin film roll is determined based on the acquired winding hardness distribution and the above first and second conditions. As a result, it is possible to inspect the presence or absence of streak defects within the roll, i.e., whether the resin film roll is a good product.

If the resin film roll is determined to be defective in the determination process, the resin film roll may be virtually divided into first to Nth regions (N is an integer of 3 or greater) in the axial direction, the average value of each of the first to Nth regions in the winding hardness distribution may be calculated, and a defect may be determined to exist in any of the first to Nth regions where the difference between the average value of each of the first to Nth regions and the average value of all of the first to Nth regions in the winding hardness distribution is 3G or greater. In this case, the location of the defect may be easily identified.

In the winding hardness distribution acquisition process, the winding hardness distribution may be acquired while moving the hammer in the axial direction at a speed of 80 mm/s or less.

The method for manufacturing a resin film roll according to the present invention comprises: a preparation step of preparing a resin film; a roll formation step of winding the resin film around a winding shaft and winding the resin film around the winding shaft while pressing a touch roll against the surface of the resin film, thereby forming a resin film roll wound with the resin film; an inspection step of inspecting the resin film roll using the inspection method according to the present invention; a modification step of modifying at least one of the long resin film prepared in the preparation step and the winding conditions in the roll formation step if the resin film roll is determined to be defective in the inspection step; and a recovery step of recovering the resin film if the resin film roll is determined to be non-defective in the inspection step.

The above manufacturing method includes an inspection step in which the resin film roll is inspected using the inspection method described above. This ensures that resin film rolls that are substantially free of streak defects (good products) can be manufactured.

In the above manufacturing method, after the above modification process, the above preparation process, the above roll formation process, and the above inspection process may be further repeated.

The modification process may involve at least one of preparing a resin film having a uniform thickness in a direction perpendicular to the longitudinal direction of the resin film in the preparation process, and correcting the pressing force of the touch roll on the resin film in the roll formation process.

The resin film roll according to the present invention is a resin film roll having a wound resin film. The surface of the resin film roll is struck with a hammer while the hammer is moved along the axial direction of the resin film roll. The deceleration from when the hammer hits the surface of the resin film roll and stops is measured, and the change in deceleration in the axial direction is obtained as a winding hardness distribution in the axial direction. The reference standard deviation, which is the standard deviation of the winding hardness distribution, is 3 or less, and the difference between the maximum and minimum values in the winding hardness distribution is 18 G or less.

The above-mentioned resin film roll is substantially free of streak-like defects. Therefore, when unwinding the resin film from the resin film roll to manufacture products using the resin film, it is easy to manufacture products with the desired properties.

When the resin film roll is virtually divided into first to Nth regions (N is an integer of 3 or greater) in the axial direction, the difference between the average value of each of the first to Nth regions in the winding hardness distribution and the average value of the entire winding hardness distribution for the first to Nth regions may be less than 3G.

One aspect of the present invention provides an inspection method capable of inspecting a resin film roll formed from a long resin film for the presence or absence of streak-like defects, and a method for manufacturing a resin film roll that includes the inspection method. Another aspect of the present invention provides a resin film roll that is substantially free of streak-like defects.

FIG. 1 is a flowchart of a method for manufacturing a resin film roll including an inspection method according to one embodiment. FIG. 2 is a schematic diagram of a winding device for producing a resin film roll. FIG. 3 is a schematic diagram of a roll having a streak-like defect. FIG. 4 is a diagram for explaining a method for obtaining the winding hardness distribution. FIG. 5 is a schematic diagram of the resin film roll as viewed from the side indicated by the white arrow in FIG. FIG. 6 is a diagram showing an example of the winding hardness distribution when a resin film roll is determined to be a defective product. FIG. 7 is a diagram showing another example of the winding hardness distribution when the resin film roll is determined to be a defective product. FIG. 8 is a diagram showing an example of the winding hardness distribution when a resin film roll is determined to be a non-defective product. FIG. 9 is a diagram illustrating another example of the touch roll. FIG. 10 is a diagram for explaining an example of a conventional defect inspection method. FIG. 11 is a diagram illustrating yet another example of the touch roll.

Embodiments of the present invention will be described below with reference to the drawings. The same or equivalent parts in the drawings will be designated by the same reference numerals, and duplicate explanations will be omitted. Dimensional proportions in the drawings do not necessarily correspond to those in the description.

Figure 1 is a flowchart of a method for manufacturing a resin film roll using an inspection method according to one embodiment. This explains an overview of the method for manufacturing a resin film roll.

As shown in FIG. 1 , when manufacturing a resin film roll, a long resin film is first prepared (preparation step S01). Next, the prepared resin film is wound into a roll to form a resin film roll (roll formation step S02). The formed resin film roll is then inspected for conformity using the inspection method of the present invention (inspection step S03). If the resin film roll is determined to be non-conforming in the inspection step S03, at least one of the prepared resin film and the winding conditions for the resin film roll is changed (change step S04). On the other hand, if the resin film roll is determined to be conforming in the inspection step S03, the resin film roll is recovered (recovery step S05). Note that if the resin film roll is determined to be conforming, the preparation step S01 and the roll formation step S02 may be performed again under the same conditions as before the inspection step S03. If the change step S04 is performed, the preparation step S01, the roll formation step S02, and the inspection step S03 may be repeated until the resin film roll is determined to be conforming in the inspection step S03. In this specification, resin film rolls include not only resin film rolls that can be sold as products, but also resin film rolls that are not sold and are used in other processes.

Next, an example of each step in the above-mentioned resin film roll manufacturing method will be described in detail.

[Preparation process]
In the preparation step S01, the long resin film F shown in FIG. 2 may be manufactured, or the long resin film F may be obtained by purchase or the like. The resin film F may be manufactured, for example, by extrusion molding. An example of the resin film F is an optical film. Examples of materials for the resin film F include polyester-based polymers, cellulose-based polymers, styrene-based polymers, polycarbonate-based polymers, polyolefin-based polymers, vinyl chloride-based polymers, amide-based polymers, imide-based polymers, sulfone-based polymers, polyethersulfone-based polymers, polyetheretherketone-based polymers, polyphenylene sulfide-based polymers, vinyl alcohol-based polymers, vinylidene chloride-based polymers, vinyl butyral-based polymers, arylate-based polymers, polyoxymethylene-based polymers, epoxy-based polymers, and acrylic-based polymers, as well as blends of the above polymers. More specifically, acrylic-based polymers (e.g., alkyl polyacrylates, alkyl polymethacrylates, etc.) and blends of the above polymers may be used.

The length of the resin film F in the longitudinal direction is not particularly limited, but is, for example, in the range of 1,000 m to 10,000 m, preferably 1,000 m to 6,000 m. The length of the resin film F in the width direction (the direction perpendicular to the longitudinal direction) is not particularly limited, but may be, for example, 2.5 m or less. Typically, the length in the width direction is 1,000 mm (1.0 m) to 2,500 mm.

The thickness of the resin film F is not particularly limited, but is, for example, in the range of 10 μm to 150 μm, preferably 30 μm to 100 μm.

[Roll forming process]
2, in the roll formation step S02, the long resin film F prepared in the preparation step S01 is transported by a transport roll R, which is part of a transport mechanism, while the resin film F is wound up by a winding device 4. In this way, a resin film roll (hereinafter simply referred to as a "roll") 2 is formed. For convenience of explanation, the roll-shaped resin film F being wound up may also be referred to as a roll 2.

An example of the winding device 4 used in the roll formation process S02 will be described using Figure 2. The winding device 4 includes a winding shaft 6, a touch roll 8, and a position adjustment mechanism 10.

The winding shaft 6 is a core for winding up the resin film F. In this embodiment, the winding shaft 6 is driven to rotate by a motor or the like, and the resin film F is wound around the winding shaft 6. This type of winding method is known as a center-drive winding method.

The winding device 4 may employ a surface-driven winding system. In this system, a drive shaft (or drive roll) separate from the touch roll 8 is pressed against the resin film F, and the drive shaft is driven to rotate. The frictional force generated in the contact area between the drive shaft and the resin film F rotates the winding shaft 6 around which the resin film F is wound. This causes the resin film F to be wound around the winding shaft 6. Alternatively, the winding device 4 may employ a combined drive system that combines the center-driven winding system and the surface-driven winding system. In the surface-driven winding system, the touch roll 8 itself may be used in place of the drive shaft. Unless otherwise specified, the winding device 4 of this embodiment employs a surface-driven winding system.

The touch roll 8 is a roll that presses the resin film F being wound around the winding shaft 6, applying a certain pressure (hereinafter also referred to as "touch pressure"). The touch pressure applied to the resin film F is, for example, 500 N/m or less, preferably 400 N/m or less, and more preferably 330 N/m or less. The lower limit of the touch pressure is typically 10 N/m, preferably 100 N/m. The touch roll 8 has a contact surface 8a that contacts the resin film F. The contact surface 8a is the outermost surface of the touch roll 8. The width of the contact surface 8a (the length in the direction of the rotation axis of the touch roll 8) is equal to or greater than the width of the resin film F (the length in the direction perpendicular to the longitudinal direction of the resin film F). The diameter of the touch roll 8 is, for example, 30 mm to 300 mm, preferably 50 mm to 200 mm, and more preferably 120 mm to 160 mm. The touch roll 8 is also sometimes called a nip roll, rider roll, press roll, etc.

An example of the touch roll 8 will be described in detail using Figure 2. The touch roll 8 has a roll body 12, a first layer 14, and a second layer 16.

The roll body 12 is the core material of the touch roll 8. The roll body 12 has a cylinder 18, a pair of end walls 19, and a pair of shafts 20. Examples of materials for the cylinder 18 include metal, carbon, and CFRP (carbon fiber reinforced plastic). Examples of metals include iron, stainless steel, and aluminum. The pair of end walls 19 close the openings at both ends of the cylinder 18. The cylinder 18 and the pair of end walls 19 form a hollow body. The pair of shafts 20 are provided in the pair of end walls 19 concentrically with the axis of the cylinder 18. Figure 2 illustrates one end wall 19 and one shaft 20 of the pair of end walls 19 and pair of shafts 20. The pair of shafts 20 are rotatably supported by a pair of support members 22. The roll body 12 may have a single shaft that penetrates the pair of end walls 19.

In this embodiment, the first layer 14 is disposed on the outer side of the roll body 12 in the radial direction of the roll body 12 (specifically, on the outer side of the cylinder 18). The first layer 14 covers the surface of the cylinder 18 of the roll body 12. In this embodiment, the first layer 14 is an elastic layer. The first layer 14 is a base layer for the second layer 16. An example of a material for the first layer 14 is rubber. The first layer 14 may be formed, for example, by wrapping a rubber sheet around the cylinder 18 in the circumferential direction, or by forming a cylindrical portion from the rubber sheet in advance and attaching the cylindrical portion to the roll body 12.

The Shore A hardness of the first layer 14 is typically 50 to 80. The first layer 14 is a layer that absorbs the reaction force (or impact) of the pressing force when the touch roll 8 is pressed against the resin film F. For example, to prevent the touch roll 8 itself from deflecting due to its own weight, it is preferable that the first layer 14 is not too thick. Preventing deflection of the touch roll 8 itself makes it easier to apply touch pressure uniformly along the width direction of the resin film F. On the other hand, to make it easier to distribute the reaction force, it is preferable that the first layer 14 is not too thin. Distributing the reaction force makes it easier to apply touch pressure uniformly along the width direction of the resin film F. Therefore, the thickness of the first layer 14 is typically 2 mm to 15 mm, preferably 3 mm to 15 mm, and more preferably 3 mm to 12 mm.

The Shore A hardness of the first layer 14 is the hardness measured by testing a 6 mm thick test piece made of the same material as the first layer 14 using a durometer type A hardness (Shore A) in accordance with JIS K 6253.

The second layer 16 is disposed radially outward of the first layer 14. The surface of the second layer 16 is the contact surface 8a. The Shore A hardness of the second layer 16 is less than the Shore A hardness of the first layer 14. In other words, the second layer 16 is softer than the first layer 14. The Shore A hardness of the second layer 16 is, for example, between 0 and 40/50 of the Shore A hardness of the first layer 14. For example, if the Shore A hardness of the first layer 14 is between 50 and 80, the Shore A hardness of the second layer 16 is between 0 and 40.

The thickness of the second layer 16 is not particularly limited, but is, for example, 0.5 mm to 10 mm, preferably 1 mm to 10 mm, and more preferably 1 mm to 7 mm.

In this embodiment, the second layer 16 is a porous layer. There are no particular limitations on the porous layer, and examples include foam materials (so-called foams) made from resin. Examples of resins that can be used to make the porous layer include polyethylene and polyurethane.

The second layer 16 may be formed, for example, by wrapping a single sheet of foam material around the first layer 14 in the circumferential direction, or by covering the outer surface of the first layer 14 with multiple rectangular (or strip-shaped) foam materials without leaving any gaps. When covering the outer surface of the first layer 14 with multiple rectangular (or strip-shaped) foam materials, for example, multiple rectangular (or strip-shaped) foam materials may be arranged in the circumferential direction so that their longitudinal directions coincide with the direction of the rotation axis of the touch roll 8, or multiple rectangular (or strip-shaped) foam materials may be wrapped around the first layer 14 so that their longitudinal directions cross the direction of the rotation axis of the touch roll 8 (or spirally).

The second layer 16 may be removably attached to the first layer 14. For example, the above-mentioned single sheet of foam material or multiple rectangular (or strip) foam materials may be attached to the outer surface of the first layer 14 using double-sided tape, a peelable adhesive, or the like.

The second layer 16 may have, for example, a multi-layer structure in the radial direction, as long as it has the above-mentioned Shore A hardness relationship with the first layer 14. If the second layer 16 has a multi-layer structure, the materials of each layer may be different, as long as the multi-layer structure of the second layer 16 satisfies the above-mentioned Shore A hardness range.

The Shore A hardness of the second layer 16 is the hardness measured by preparing a 6 mm thick test piece made of the same material as the second layer 16 and testing it with a Type A durometer in accordance with JIS K6253. Alternatively, if the second layer 16 has a laminated structure including multiple layers, the Shore A hardness of each layer of the second layer 16 may be the Type A durometer hardness (Shore A) specified in JIS K6253 for each 6 mm thick test piece made of the same material as each layer.

The touch roll 8 is rotatably supported by a pair of support members 22. The support members 22 may be plate-shaped or rod-shaped.

The position adjustment mechanism 10 is a mechanism that moves one of the winding shaft 6 and the touch roll 8 relative to the other so that the contact surface 8a of the touch roll 8 comes into contact with the resin film F with a pressing force that applies a constant touch pressure, as indicated by the white arrow in Figure 2.

In the embodiment illustrated in FIG. 2, the touch roll 8 is moved relative to the winding shaft 6. In the embodiment illustrated in FIG. 2, the position adjustment mechanism 10 is a cylinder. The position adjustment mechanism 10 has a cylinder body 24 and a cylinder rod 26 that is extendable and retractable relative to the cylinder body 24. The cylinder rod 26 is connected to the support member 22. Examples of cylinders that are the position adjustment mechanism 10 include hydraulic cylinders and air cylinders. The position adjustment mechanism 10 may also be an actuator. The position adjustment mechanism 10 may be, for example, a swing-type mechanism. For example, the end of one of the pair of support members 22 opposite the touch roll 8 may be attached to the support shaft so that it can swing. In this case, the support shaft functions as the position adjustment mechanism 10. The pair of support members 22 may be part of the position adjustment mechanism 10.

The position adjustment mechanism 10 may include, for example, a control unit that controls the cylinder to adjust the position of the touch roll 8 so that a constant touch pressure can be applied to the resin film F depending on the amount of resin film F wound around the winding shaft 6. The control unit may be included in the cylinder, for example.

The position adjustment mechanism 10 allows the touch roll 8 to retract accordingly, even if the diameter of the roll 2 changes as the resin film F is continuously wound around the winding shaft 6. As a result, a constant touch pressure can be applied to the contact area between the contact surface 8a and the surface of the resin film F. The contact area has a rectangular shape extending in the width direction of the resin film F.

[Inspection process]
In the inspection step S03, the roll 2 formed in the roll forming step S02 is inspected to determine whether it is a non-defective product. Specifically, as shown in FIG. 3, the roll 2 is inspected for the presence or absence of a streak-like defect D. The defect D is, for example, a defect extending in the circumferential direction of the roll 2. In the inspection step S03, the roll 2 is inspected by an inspection method described below. As shown in FIG. 1, the inspection method includes a winding hardness distribution acquisition step S03A and a determination step S03B.

<Winding hardness distribution acquisition process>
4 and 5, in the winding hardness distribution acquisition step S03A, the winding hardness distribution in the axial direction C of the roll 2 is acquired by the hardness measuring device 28. Fig. 5 is a schematic diagram of the roll 2 as viewed from the side indicated by the white arrow in Fig. 4.

The hardness tester 28 has a hammer 30 attached to its bottom surface so as to strike the roll surface (resin film roll surface) 2a. The hardness tester 28 strikes the roll surface 2a with the hammer 30 and measures the deceleration until the hammer 30 hits the roll surface 2a and stops. Because the deceleration varies depending on the winding hardness of the roll 2 at the point struck by the hammer 30, the deceleration corresponds to the winding hardness. The hardness tester 28 has a pair of spacer members 32 on its bottom surface on both sides of the hammer 30 to ensure a gap between the roll surface 2a and the bottom surface so that the hammer 30 can strike the roll surface 2a. An example of a hardness tester 28 is the RoQ roll hardness tester manufactured by ACA Systems. Although neither is particularly limited, the vibration frequency of the hammer 30 (number of strikes per second) may be, for example, 30 to 70 Hz, specifically 50 Hz (average 35 Hz), and the speed of the hammer 30 (speed of strikes per second) may be, for example, 0.1 to 0.5 m/s, specifically 0.15 to 0.3 m/s, and more specifically approximately 0.25 m/s.

In the winding hardness distribution acquisition step S03A, as shown in FIG. 4, the hardness measuring device 28 is moved from one end of the roll 2 to the other while striking the roll surface 2a with the hammer 30, and the deceleration from when the hammer 30 hits the roll surface 2a until it stops is measured, and the change in deceleration in the axial direction C is acquired as the winding hardness distribution. The movement speed of the hardness measuring device 28 is not particularly limited, but is, for example, 80 mm/s or less, preferably 70 mm/s or less, more preferably 50 mm/s or less, and may be 20 mm/s or more.

<Judgment process>
In the judgment step S03B, the quality of the roll 2 is judged based on the acquired winding hardness distribution. Specifically, if both the following first and second conditions are satisfied, the roll 2 is judged to be a good product, and if at least one of the first and second conditions is not satisfied, the roll 2 is judged to be a defective product.
(First condition)
The reference standard deviation, which is the standard deviation of the winding hardness distribution, is 3 or less.
(Second condition)
The second condition is that the difference between the maximum value and the minimum value in the winding hardness distribution is 18 G or less.

At both ends of roll 2 (the measurement start and end points), the winding hardness may differ significantly from the actual value due to measurement error. For this reason, when applying the first and second conditions, measurements at both ends of roll 2 or at both ends and their vicinity are usually excluded. For example, the first and second conditions can be determined based on measurements excluding a few measurements from both ends (for example, five measurements from both ends if measurements are taken at 1 mm intervals). In this way, when measurements at both ends of roll 2 or at both ends and their vicinity are excluded, the "reference standard deviation" is the standard deviation of all remaining measurements excluding the several measurements from both ends.

Examples of winding hardness distributions are shown in Figures 6 to 8. Figures 6 to 8 show winding hardness distributions based on the results of measuring the winding hardness of the following resin film roll using an RoQ roll hardness tester manufactured by ACA Systems as the hardness tester 28 while moving the hardness tester 28 at 50 mm/s and in 1 mm intervals (hammer speed: approximately 0.25 m/s).
FIG. 6 shows the winding hardness distribution of a resin film roll obtained by winding a polymethyl methacrylate resin film (thickness: 80 μm, width direction length: 1490 mm, length direction length: 4100 mm) using the winding device shown in FIG. 2 .
FIG. 7 shows the winding hardness distribution of a resin film roll obtained by winding a polymethyl methacrylate resin film (thickness: 60 μm, width direction length: 1490 mm, length direction length: 3250 mm) using the winding device shown in FIG. 2 .
FIG. 8 shows the winding hardness distribution of a resin film roll obtained by winding a polymethyl methacrylate resin film (thickness: 80 μm, width direction length: 1490 mm, length direction length: 3650 mm) using the winding device shown in FIG. 2 .

Figures 6 and 7 show the results of actually measuring the winding hardness when Roll 2 is a defective product. Figure 8 shows the results of actually measuring the winding hardness when Roll 2 is a non-defective product. In the Roll 2 for which the measurement results in Figures 6 and 7 were obtained, defect D was present near one end of Roll 2, as shown in Figure 3. The winding hardness distributions shown in Figures 6 to 8 are the results when the winding conditions were the same except for different conditions.

Figures 6 to 8 show the measurement results excluding the five measurement results from both ends of all measurement values. The vertical axis in Figures 6 to 8 shows the hardness measurement value (G) from the hardness measuring device 28. The unit of hardness measurement, "G," indicates gravitational acceleration. The horizontal axis in Figures 6 to 8 shows the position in the width direction of the roll 2 (position in the axial direction C). The positions P1 and P2 on the horizontal axis in Figures 6 to 8 correspond to the positions excluding the five measurement results from both ends of all measurement values.

If the roll 2 is determined to be defective in the determination step S03B, the location of the defect D may be determined as follows. That is, as shown in Figure 4, the roll 2 is virtually divided into first to Nth regions (N is an integer of 3 or greater) in the axial direction C. Typically, the first to Nth regions have equal lengths in the axial direction C. N may also be an integer of 25 or less.

The first through Nth average values corresponding to the first through Nth regions in the winding hardness distribution are calculated, and a defect D is further determined to exist in a region of the first through Nth regions where the difference between the first through Nth average value and the average value for the entire first through Nth regions in the winding hardness distribution (hereinafter referred to as the "reference average value") is 3G or greater. Figure 4 illustrates the case where N=3, where the roll 2 is virtually divided into first through third regions A1, A2, and A3. The first through Nth regions may be, for example, regions obtained by dividing the roll 2 into N equal parts. As described above, if the above-mentioned several measurement values from both ends of the total measurement values are excluded, the calculation of the average values of the first through Nth regions and the reference average value may be performed on the winding hardness distribution formed by all the remaining measurement values after excluding the above-mentioned several measurement values from both ends of the total measurement values. While the example shows the case where the entire roll 2 is divided into first through Nth regions, the first through Nth regions do not necessarily have to be regions obtained by dividing the entire roll 2. For example, if several measurement values are removed from both ends of the total measurement values as described above, the roll area corresponding to the acquisition range of the removed valid measurement values may be divided into first through Nth areas.

<Change process>
If the roll 2 is determined to be defective in the inspection step S03 ("NO" in the inspection step S03 in FIG. 1), the change step S04 is performed. In the change step S04, at least one of the resin film F prepared in the preparation step S01 and the winding conditions in the roll formation step S02 is changed.

(Example of change of resin film F prepared in preparation step S01)
The resin film F is changed to a resin film F having a more uniform thickness in the width direction (direction perpendicular to the longitudinal direction) of the resin film F, for example. When preparing the resin film F by manufacturing the resin film F, the manufacturing conditions of the resin film F are changed. For example, the extrusion molding conditions may be adjusted so that the thickness of the resin film F in the width direction becomes uniform. When preparing the resin film by purchasing the resin film F, the resin film F may be replaced with another purchased resin film F.

(Example of changing winding conditions)
When the winding conditions are changed, for example, the touch pressure or the transport speed is corrected. The touch pressure can be adjusted by the position adjustment mechanism 10. The touch pressure can also be adjusted by changing the configuration of the touch roll 8. Therefore, the touch pressure may be adjusted by changing the touch roll 8.

For example, in the touch roll 8, at least one of the thickness of the first layer 14, the Shore A hardness of the first layer 14, the thickness of the second layer 16, and the Shore A hardness of the second layer 16 may be changed, or the touch roll may be changed to one that does not have the second layer 16 (i.e., a touch roll in which the surface of the first layer is the contact surface), or conversely, a touch roll that does not have the first layer 14 may be used. Furthermore, the touch roll 34 shown in Figure 9 may be used as the touch roll 8.

The touch roll 34 differs from the touch roll 8 in that it has a second layer 36 instead of the second layer 16. The second layer 36 has an inner layer 38 and an outer layer 40. Both the inner layer 38 and the outer layer 40 are porous layers (e.g., sponge layers). The A Shore hardnesses of the inner layer 38 and the outer layer 40 are lower than the A Shore hardness of the first layer 14, and the A Shore hardness of the inner layer 38 is lower than the A Shore hardness of the outer layer 40. In other words, the inner layer 38 and the outer layer 40 are softer than the first layer 14, and the outer layer 40 is harder than the inner layer 38. For example, the A Shore hardness of the inner layer 38 is typically 0 to 20, and the A Shore hardness of the outer layer 40 is typically 20 to 40. Because the Shore A hardness of the inner layer 38 is lower than the Shore A hardness of the outer layer 40, if one of the illustrated inner layer 38 and outer layer 40 includes a region where the Shore A hardness is 20, the other does not include a region where the Shore A hardness is 20. The inner layer 38 may be detachable from the first layer 14, for example. The outer layer 40 may be detachable from the inner layer 38.

If the modification process S04 is performed, the preparation process S01, roll formation process S02, inspection process S03, and modification process S04 are repeated until the roll 2 is determined to be a non-defective product in the inspection process S03.

<Recovery process>
If the roll 2 is determined to be a non-defective product in the inspection step S03 ("YES" in the inspection step S03 in FIG. 1), the recovery step S05 is carried out.

In the recovery process S05, the preparation process S01 and roll formation process S02, which were carried out to form the roll 2 determined to be a non-defective product in the inspection process S03, are carried out again to produce and recover a non-defective roll 2.

As a result, when the roll 2 (non-defective roll) collected in the collection step S05 is subjected to a step similar to the winding hardness distribution acquisition step S03A included in the inspection step S03, the acquired winding hardness distribution satisfies both the first and second conditions. In other words, the non-defective roll 2 is a resin film roll that is substantially free of defect D.

Furthermore, for the non-defective roll 2 collected in the collection step S05, when the roll 2 is virtually divided into first through Nth regions in the axial direction C and the first through Nth average values corresponding to the first through Nth regions in the obtained winding hardness distribution are calculated, the difference between the first through Nth average values and the reference average value may be less than 3 G. In other words, the non-defective roll 2 is a resin film roll that does not substantially contain defect D in any of the first through Nth regions. The method of dividing the roll 2 into the first through Nth regions and the method of calculating the average value and the reference average value are the same as those described in the determination step S03B.

In the above-described resin film roll manufacturing method, the inspection step S02 shown in Figure 1 employs an inspection method according to one embodiment, thereby ensuring the manufacture of resin film rolls that are substantially free of defect D shown in Figure 3. A detailed explanation is provided below.

It is believed that defect D is caused by wrinkles formed when air is entrained in the resin film F when it is wound up in the roll formation process S02. The presence or absence of defect D has traditionally been determined by shining light onto roll 2 from a light source 42 located on one side of roll 2 and visually observing the transmitted light, as shown in Figure 10. With this method, the area where defect D occurs becomes dark, making it possible to determine the presence or absence of defect D. Figure 3 shows a schematic representation of defect D that appears in such an appearance inspection. However, because it is a visual inspection, it is easily influenced by subjectivity. Furthermore, if defect D is not near the surface, the presence or absence of defect D cannot be determined even with the method of Figure 10.

The inventors of the present application conducted extensive research into determining the presence or absence of defect D. As a result, they discovered that the winding hardness at the location of defect D is significantly different from that at locations where defect D is not present, i.e., that there is a correlation between the winding hardness distribution and the location where defect D occurs. Furthermore, they discovered that the presence of defect D can be determined when either the first or second condition described in determination step S03B is not met.

In inspection step S03, the winding hardness distribution in the axial direction C of roll 2 is obtained. If the winding hardness distribution does not satisfy either the first condition or the second condition, roll 2 is judged to be a defective product, and if it satisfies both the first condition and the second condition, roll 2 is judged to be a non-defective product. Therefore, the quality of roll 2 can be judged after it is formed. Furthermore, because the quality of roll 2 is judged based on the winding hardness distribution, the quality of roll 2 can be judged objectively.

The inspection process S03 will now be described in detail based on the measurement results shown in Figures 6, 7, and 8 above.

In Figure 6, the reference standard deviation for the winding hardness distribution was 3.2, the maximum winding hardness was 143.1 G, and the minimum winding hardness was 113.3 G. In other words, the difference between the maximum and minimum winding hardness values was 29.80 G. Therefore, the resin film roll corresponding to the results shown in Figure 6 did not satisfy Condition 1 or Condition 2.

In Figure 7, the reference standard deviation for the winding hardness distribution was 2.9, the maximum winding hardness was 148.0 G, and the minimum winding hardness was 118.7 G. In other words, the difference between the maximum and minimum winding hardness values was 29.30 G. Therefore, the resin film roll corresponding to the results shown in Figure 7 satisfied condition 1 but did not satisfy condition 2.

On the other hand, in Figure 8, the reference standard deviation for the winding hardness distribution was 1.9, the maximum winding hardness was 144.5 G, and the minimum winding hardness was 133.6 G. In other words, the difference between the maximum and minimum winding hardness values was 10.90 G. Therefore, the resin film roll corresponding to the results shown in Figure 7 satisfied both Condition 1 and Condition 2.

When the resin film rolls having the winding hardness distributions shown in Figures 6 to 8 were visually inspected as described using Figure 10, streak-like defects were observed in the resin film rolls having the winding hardness distributions shown in Figures 6 and 7, while no streak-like defects were observed in the resin film rolls having the winding hardness distribution shown in Figure 8. Furthermore, no streak-like defects were observed when the resin film roll having the winding hardness distribution shown in Figure 8 was unwound. In other words, the quality of roll 2 could be determined through the inspection in inspection step S03.

In the resin film roll manufacturing method including the inspection step S03, the modification step S04 is performed based on the results of the inspection step S03, making it possible to manufacture a roll 2 that is substantially free of defect D (i.e., a non-defective roll).

In an embodiment in which the touch roll 8 includes the first layer 14 and the second layer 16, even if the surface of the resin film F is uneven, the second layer 16 conforms to the unevenness of the surface of the resin film F. Furthermore, because the first layer 14 is interposed between the roll body 12 and the second layer 16, the hardness (or elasticity) of the first layer 14 can absorb strong pressure generated at the convex portions of the resin film F. As a result, touch pressure can be applied uniformly across the width of the contact area between the touch roll 8 and the resin film F. This makes it easier to prevent air entrapment when winding the resin film F. This makes it even easier to manufacture a roll 2 that is substantially free of defects D. Because the touch roll 8 can be adjusted using parameters such as the thickness and Shore A hardness of the first layer 14 and the second layer 16, changing the winding conditions in the change step S04 is easy.

If the second layer 16 is detachable from the first layer 14, it is easy to change the second layer 16, for example, in the changing step S04. This reduces the time required to manufacture a good roll 2.

When the touch roll 34 shown in Figure 9 is used instead of the touch roll 8, the inner layer 38 of the second layer 36 of the touch roll 34 is softer than the outer layer 40, allowing it to conform to the irregularities on the surface of the resin film F. Because the second layer 36 has an outer layer 40 that is harder than the inner layer 38, deterioration and damage (scratches, wear, etc.) of the second layer 36 can be prevented more effectively than if the inner layer 38 were in direct contact with the resin film F. Furthermore, the length of the contact area between the touch roll 34 and the resin film F in the transverse direction tends to be shorter. This makes it possible to more reliably press the surface of the resin film F with a constant touch pressure, further preventing air entrapment. Therefore, in an embodiment in which the touch roll 34 is used in the roll formation step S02, it is easier to manufacture a roll 2 that is substantially free of defects D.

In an embodiment in which, as described above, a region containing defect D is identified among the first to Nth virtually divided regions of roll 2 for a roll determined to be defective, as shown in FIG. 4, when roll 2 is virtually divided into first to Nth regions (N = 3 in FIG. 4), the first to Nth average values corresponding to the first to Nth regions in the winding hardness distribution are calculated, and defect D is determined to be present in a region among the first to Nth regions where the difference between the first to Nth average value and the reference average value is 3 G or more. In this case, since the location where defect D occurs in the axial direction C of roll 2 can be identified, it is easy to perform the modification step S04 to prevent defect D from occurring. For example, if resin film F is manufactured by extrusion molding, it is easy to reliably adjust the thickness of resin film F at the location where defect D occurs. This reduces the time required to manufacture a good roll 2.

The roll 2 obtained by the manufacturing method of the present invention can be used as a raw roll for manufacturing other products. Because the resin film F unwound from the roll 2 is substantially free of defects D, products with desired properties can be manufactured from the raw roll.

The roll body 12 does not necessarily have to have a pair of shafts 20. In this case, a rotating shaft may be prepared separately from the touch roll 8, and the rotating shaft may be passed through the touch roll, which is the roll body 12 itself, and rotatably supported by a pair of support members 22. The roll body 12 may have, for example, a cylindrical body (solid body) and a pair of shafts 20. In this case, the pair of shafts 20 are provided on both end faces in the axial direction of the body, concentric with the axis of the body.

The resin film F may be a polarizing film or a retardation film produced by further applying a stretching process to a film produced by extrusion molding, as shown in the example.

In the above example, the first layer 14 and second layer 16 of the touch roll 8 are, for example, a rubber layer, and the second layer 16 is a foam material layer. However, as long as the first layer 14 and second layer 16 have the hardness relationship shown in the example, the first layer 14 may be a porous layer and the second layer 16 may be a non-porous layer. The second layer 16 may be made of rubber as long as its A Shore hardness is lower than that of the first layer.

The touch roll may be the touch roll 44 shown in Figure 11. The touch roll 44 differs from the touch roll 8 in that it has a second layer 46 instead of the second layer 16. The relationship of the A Shore hardness of the second layer 46 to the first layer 21 is the same as that of the second layer 16, and examples of materials for the second layer 46 are the same as those for the second layer 16. Below, the second layer 46 will be described, focusing on the differences from the second layer 16.

The second layer 46 has multiple regions 46a, 46b, and 46c, in this order, along the width direction. Regions 46a, 46b, and 46c have the same thickness. The A Shore hardness of at least one of regions 46a, 46b, and 46c is different from the A Shore hardness of the other regions. For example, the A Shore hardness of regions 46a and 46c is the same and is smaller (or larger) than the A Shore hardness of region 46b. The difference in A Shore hardness can be achieved by using different materials.

Figure 11 illustrates an example in which the second layer 46 has three regions in the width direction, but the number of regions is not limited to three. The A Shore hardness of the multiple regions that the second layer 46 has in the width direction and the width direction length of each region may be set so that a uniform touch pressure can be applied to the resin film F in the width direction.

The present invention is not limited to the various embodiments described above. The various embodiments and modifications described above can be combined as appropriate without departing from the spirit of the present invention.

2...roll (resin film roll), 2a...roll surface, 8...touch roll, 30...hammer, C...axial direction, F...resin film.

Claims (4)

a preparation step of preparing a resin film;
a roll forming step of winding the resin film around a winding shaft and winding the resin film around the winding shaft while pressing a touch roll against the surface of the resin film, thereby forming a resin film roll comprising the resin film wound around the winding shaft;
an inspection step of inspecting the resin film roll;
a changing step of changing winding conditions in the roll forming step when the resin film roll is determined to be defective in the inspection step;
a recovery step of recovering the resin film roll when the resin film roll is determined to be free of defects in the inspection step;
Equipped with
The inspection step includes:
a winding hardness distribution acquisition step of striking the surface of the resin film roll with a hammer while moving the hammer along the axial direction of the resin film roll formed by winding a resin film, measuring the deceleration until the hammer hits the surface of the resin film roll and stops, and acquiring the change in the deceleration in the axial direction as a winding hardness distribution in the axial direction;
a determination step of determining whether or not there is a defect in the resin film roll based on the winding hardness distribution;
Equipped with
In the determination step, the resin film roll is determined to be free of defects when both a first condition and a second condition are satisfied, and the resin film roll is determined to be defective when at least one of the first condition and the second condition is not satisfied,
The first condition is that a reference standard deviation, which is a standard deviation of the winding hardness distribution, is 3 or less,
the second condition is that the difference between the maximum value and the minimum value in the winding hardness distribution is 18 G or less,
the defect is a streak-like defect extending in the circumferential direction of the resin film roll, which is caused by entrapment of air,
In the changing step, the pressing force of the touch roll against the resin film is corrected in the roll forming step.
A method for manufacturing a resin film roll. If it is determined that there is a defect in the determination step,
The resin film roll is virtually divided into first to Nth regions (N is an integer of 3 or more) in the axial direction,
an average value for each of the first to Nth regions in the winding hardness distribution is calculated, and it is further determined that a defect exists in a region of the first to Nth regions where a difference between each average value in the first to Nth regions and an average value for all of the first to Nth regions in the winding hardness distribution is 3 G or more;
The method for producing a resin film roll according to claim 1 . In the winding hardness distribution acquisition step, the winding hardness distribution is acquired while moving the hammer in the axial direction at a speed of 80 mm/s or less.
The method for producing a resin film roll according to claim 1 or 2. After the changing step is performed, the preparing step, the roll forming step, and the inspecting step are further repeated.
The method for producing a resin film roll according to any one of claims 1 to 3.